FOAMABLE THERMOPLASTIC POLYESTER COPOLYMER

Abstract

The present invention relates to a thermoplastic polyester copolymer comprising 50-1000 ppm with regard to the total weight of the thermoplastic polyester copolymer of moieties derived from an alcohol having 3 hydroxy moieties. Such thermoplastic polyester copolymer allows for the production of high-quality foamed articles, whilst reducing the need for additives that are to be incorporated in the copolymer.

Claims

1. A thermoplastic polyester copolymer comprising 50-1000 ppm with regard to the total weight of the thermoplastic polyester copolymer of moieties derived from an alcohol having 3 hydroxy moieties, wherein the thermoplastic polyester copolymer comprises 0.5 and 8.0 wt % of moieties derived from a chain extender with regard to the total weight of the thermoplastic polyester copolymer.

2. The thermoplastic polyester copolymer according to claim 1 wherein the chain extender is selected from diepoxides, dianhydrides, diisocyanates, bisoxazines, bisoxazolines or bislactams.

3. The thermoplastic polyester copolymer according to claim 1, wherein the chain extender is a compound selected from 2,2-methylene-bis(4,1-phenyleneoxy)bisoxirane, 2,2-ethylidene-bis(4,1-phenyleneoxy)bisoxirane, 2,2-(1-methylethylidene)-bis(4,1-phenyleneoxy)bisoxirane, 2,2-ethylidene-bis(4,1-phenyleneoxy)bisoxirane, 2,2-(1-methylethylidene)-bis(4,1-phenyleneoxy)bis(3-methyl-oxirane), 4,4-bis(1,2-epoxypropoxy)biphenyl, 2,2-((1,1-biphenyl])-4,4-diylbis(oxy))bisoxirane, 1,4-bis(1,2-epoxypropoxy)benzene, 2,2-(1,4-phenylenebis(oxy)bisoxirane, 2,2-((1,1-binaphthalene)-2,2-diylbis(oxy))bisoxirane, ((6-oxiranylmethoxy(2,2-binaphthalene)-6-yl)oxy)oxirane, 2,2-(1,6-naphthalenediylbis(oxy))bisoxirane, 2,2-((1,1-biphenyl)-4,4-diylbis(oxy))bis(2-methyl-oxirane), 2,2-(2,6-naphthalenediylbis(oxy))bis(2-methyl-oxirane), 2,2-(methylenebis(4,1-phenyleneoxy))bis(2-methyl-oxirane), 2,2-(1,4-phenylenebis(oxy))bis(2-methyl-oxirane), (2-methyl-4-((oxiranyloxy)methyl)phenoxy)oxirane, or (2,6-dimethyl-4-((oxiranyloxy)methyl)phenoxy)oxirane, ((oxiranyloxy)methyl)phenoxy)oxirane.

4. The thermoplastic polyester copolymer according to claim 1, wherein the chain extender is 2,2-(1-methylethylidene)-bis(4,1-phenyleneoxy)bisoxirane.

5. The thermoplastic polyester copolymer according to claim 1, wherein the thermoplastic polyester copolymer is a polymer selected from a poly(ethylene terephthalate) copolymer, a poly(trimethylene terephthalate) copolymer, a poly(butylene terephthalate) copolymer, a poly(ethylene naphthalate) copolymer, or a poly(ethylene furanoate) copolymer,

6. The thermoplastic polyester copolymer according to claim 1, wherein the alcohol is a compound according to the formula:
[R1OH.sub.n wherein R1 is a moiety comprising 1-10 carbon atoms and wherein n is an integer 3 and 6.

7. The thermoplastic polyester copolymer according to claim 6, wherein R1 is a moiety selected from methyl, ethyl, propyl, tert-butyl, neopentyl, or hexamethylethyl.

8. The thermoplastic polyester copolymer according to claim 1, wherein the alcohol having 3 hydroxy moieties is selected from tetrahydroxymethane, trihydroxymethane, 1,1,2,2-tetrahydroxyethane, hexahydroxyethane, glycerol, 1,3,5-pentanetriol, xylitol, pentaerythritol, 2,2,3,3-tetrakis(hydroxymethyl)-1,4-butanediol, 2,3-bis(hydroxymethyl)-1,4-butanediol, tris(2-hydroxyethyl)methane, or tetrakis(2-hydroxyethyl)methane.

9. Thermoplastic The thermoplastic polyester copolymer according to claim 1, wherein the thermoplastic polyester copolymer comprises 95.0 wt % of moieties derived from ethylene glycol and terephthalic acid or a diester thereof, with regard to the total weight of the thermoplastic polyester copolymer.

10. The thermoplastic polyester copolymer according to claim 1, wherein the thermoplastic polyester copolymer has an intrinsic viscosity of 0.60 dl/g and 2.00 dl/g as determined in accordance with ASTM D2857-95 (2007).

11. A process for the production of a thermoplastic polyester copolymer according to claim 1, wherein the process comprises the steps of first an esterification step in which a composition comprising an alkylene diol, a dicarboxylic acid or diester thereof and an alcohol having 3 hydroxy moieties react to form a polyester oligomer which is subsequently subjected to polycondensation at a pressure of 0.005 bar at a temperature of 275-300 C. to obtain a polycondensation product which upon solidification and drying is subjected to solid-state polycondensation at a temperature of 200-220 C. under a vacuum of 20 for a period of 5-50 hours.

12. A foam comprising the thermoplastic polyester copolymer according to claim 1.

13. The foam according to claim 12 having a density of <100 kg/m.sup.3 as determined in accordance with ASTM D6226 (2010).

14. The foam according to claim 12 having an open cell content of 15.0% as determined in accordance with ASTM D6226 (2010).

15. A process for the production of a foam via an extrusion moulding process comprising a first twin-screw melt extruder and a second single-screw melt extruder positioned in series, wherein a feed composition comprising the thermoplastic polyester copolymer according to claim 1 is introduced to the feed inlet of the first twin-screw melt extruder, wherein a quantity of a blowing agent is introduced to the first twin-screw melt extruder, and wherein the molten composition comprising the thermoplastic polyester copolymer and the blowing agent upon exiting the twin-screw melt extruder is fed to the feed inlet of the single-screw melt extruder and extruder from the single-screw melt extruder through a die to form a foam.

16. The thermoplastic polyester copolymer according to claim 1, wherein the chain extender is a compound selected from 2,2-methylene-bis(4,1-phenyleneoxy)bisoxirane, 2,2-ethylidene-bis(4,1-phenyleneoxy)bisoxirane, 2,2-(1-methylethylidene)-bis(4,1-phenyleneoxy)bisoxirane, 2,2-ethylidene-bis(4,1-phenyleneoxy)bisoxirane, 2,2-(1-methylethylidene)-bis(4,1-phenyleneoxy)bis(3-methyl-oxirane), 4,4-bis(1,2-epoxypropoxy)biphenyl, 2,2-((1,1-biphenyl])-4,4-diylbis(oxy))bisoxirane, 1,4-bis(1,2-epoxypropoxy)benzene, 2,2-(1,4-phenylenebis(oxy)bisoxirane, 2,2-((1,1-binaphthalene)-2,2-diylbis(oxy))bisoxirane, ((6-oxiranylmethoxy(2,2-binaphthalene)-6-yl)oxy)oxirane, 2,2-(1,6-naphthalenediylbis(oxy))bisoxirane, 2,2-((1,1-biphenyl)-4,4-diylbis(oxy))bis(2-methyl-oxirane), 2,2-(2,6-naphthalenediylbis(oxy))bis(2-methyl-oxirane), 2,2-(methylenebis(4,1-phenyleneoxy))bis(2-methyl-oxirane), 2,2-(1,4-phenylenebis(oxy))bis(2-methyl-oxirane), (2-methyl-4-((oxiranyloxy)methyl)phenoxy)oxirane, or (2,6-dimethyl-4-((oxiranyloxy)methyl)phenoxy)oxirane; wherein the thermoplastic polyester copolymer is a polymer selected from a poly(ethylene terephthalate) copolymer, a poly(trimethylene terephthalate) copolymer, a poly(butylene terephthalate) copolymer, a poly(ethylene naphthalate) copolymer, or a poly(ethylene furanoate) copolymer; wherein the alcohol is a compound according to the formula:
[R1OH.sub.n wherein R1 is a moiety comprising 1-10 carbon atoms and wherein n is an integer 3 and 6; wherein the thermoplastic polyester copolymer comprises 95.0 wt % of moieties derived from ethylene glycol and terephthalic acid or a diester thereof, with regard to the total weight of the thermoplastic polyester copolymer; and wherein the thermoplastic polyester copolymer has an intrinsic viscosity of 0.60 dl/g and 2.00 dl/g as determined in accordance with ASTM D2857-95 (2007).

17. The thermoplastic polyester copolymer according to claim 16, wherein R1 is a moiety selected from methyl, ethyl, propyl, tert-butyl, neopentyl, or hexamethylethyl; and wherein the chain extender is 2,2-(1-methylethylidene)-bis(4,1-phenyleneoxy)bisoxirane.

18. The thermoplastic polyester copolymer according to claim 17, wherein the alcohol having 3 hydroxy moieties is selected from tetrahydroxymethane, trihydroxymethane, 1,1,2,2-tetrahydroxyethane, hexahydroxyethane, glycerol, 1,3,5-pentanetriol, xylitol, pentaerythritol, 2,2,3,3-tetrakis(hydroxymethyl)-1,4-butanediol, 2,3-bis(hydroxymethyl)-1,4-butanediol, tris(2-hydroxyethyl)methane, or tetrakis(2-hydroxyethyl)methane.

Description

[0057] In certain of its embodiments, the present invention relates to the aspects presented hereinbelow.

[0058] Aspect 1: Thermoplastic polyester copolymer comprising 50-1000 ppm with regard to the total weight of the thermoplastic polyester copolymer of moieties derived from an alcohol having 3 hydroxy moieties.

[0059] Aspect 2: Thermoplastic polyester copolymer according to aspect 1 wherein the thermoplastic polyester copolymer is a polymer selected from a poly(ethylene terephthalate) copolymer, a poly(trimethylene terephthalate) copolymer, a poly(butylene terephthalate) copolymer, a poly(ethylene naphthalate) copolymer, or a poly(ethylene furanoate) copolymer,

[0060] Aspect 3: Thermoplastic polyester copolymer according to any one of aspects 1-2, wherein the alcohol is a compound according to the formula:

[R1OH.sub.n

wherein R1 is a moiety comprising 1-10 carbon atoms and wherein n is an integer 3 and 6.

[0061] Aspect 4: Thermoplastic polyester copolymer according to claim 3, wherein R1 is a moiety selected from methyl, ethyl, propyl, tert-butyl, neopentyl, or hexamethylethyl.

[0062] Aspect 5: Thermoplastic polyester copolymer according to any one of aspects 1-3, wherein the alcohol having 3 hydroxy moieties is selected from tetrahydroxymethane, trihydroxymethane, 1,1,2,2-tetrahydroxyethane, hexahydroxyethane, glycerol, 1,3,5-pentanetriol, xylitol, pentaerythritol, 2,2,3,3-tetrakis(hydroxymethyl)-1,4-butanediol, 2,3-bis(hydroxymethyl)-1,4-butanediol, tris(2-hydroxyethyl)methane, or tetrakis(2-hydroxyethyl)methane.

[0063] Aspect 6: Thermoplastic polyester copolymer according to any one of aspects 1-5, wherein the thermoplastic polyester copolymer comprises 95.0 wt % of moieties derived from ethylene glycol and terephthalic acid or a diester thereof, with regard to the total weight of the thermoplastic polyester copolymer.

[0064] Aspect 7: Thermoplastic polyester copolymer according to any one of aspects 1-6, wherein the thermoplastic polyester copolymer has an intrinsic viscosity of 0.60 dl/g and 2.00 dl/g as determined in accordance with ASTM D2857-95 (2007).

[0065] Aspect 8: Thermoplastic polyester copolymer according to any one of aspects 1-7, wherein the thermoplastic polyester copolymer comprises 0.5 and 8.0 wt % of moieties derived from a chain extender with regard to the total weight of the thermoplastic polyester copolymer.

[0066] Aspect 9: Thermoplastic polyester copolymer according to aspect 8 wherein the chain extender is selected from diepoxides, dianhydrides, diisocyanates, bisoxazines, bisoxazolines or bislactams.

[0067] Aspect 10: Thermoplastic polyester copolymer according to aspect 8 wherein the chain extender is a compound selected from 2,2-methylene-bis(4,1-phenyleneoxy)bisoxirane, 2,2-ethylidene-bis(4,1-phenyleneoxy)bisoxirane, 2,2-(1-methylethylidene)-bis(4,1-phenyleneoxy)bisoxirane, 2,2-ethylidene-bis(4,1-phenyleneoxy)bisoxirane, 2,2-(1-methylethylidene)-bis(4,1-phenyleneoxy)bis(3-methyl-oxirane), 4,4-bis(1,2-epoxypropoxy)biphenyl, 2,2-((1,1-biphenyl])-4,4-diylbis(oxy))bisoxirane, 1,4-bis(1,2-epoxypropoxy)benzene, 2,2-(1,4-phenylenebis(oxy)bisoxirane, 2,2-((1,1-binaphthalene)-2,2-diylbis(oxy))bisoxirane, ((6-oxiranylmethoxy(2,2-binaphthalene)-6-yl)oxy)oxirane, 2,2-(1,6-naphthalenediylbis(oxy))bisoxirane, 2,2-((1,1-biphenyl)-4,4-diylbis(oxy))bis(2-methyl-oxirane), 2,2-(2,6-naphthalenediylbis(oxy))bis(2-methyl-oxirane), 2,2-(methylenebis(4,1-phenyleneoxy))bis(2-methyl-oxirane), 2,2-(1,4-phenylenebis(oxy))bis(2-methyl-oxirane), (2-methyl-4-((oxiranyloxy)methyl)phenoxy)oxirane, or (2,6-dimethyl-4-((oxiranyloxy)methyl)phenoxy)oxirane, preferably 2,2-(1-methylethylidene)-bis(4,1-phenyleneoxy)bisoxirane.

[0068] Aspect 11: Process for the production of a thermoplastic polyester copolymer according to any one of aspects 1-10 wherein the process comprises the steps of first an esterification step in which a composition comprising an alkylene diol, a dicarboxylic acid or diester thereof and an alcohol having 3 hydroxy moieties react to form a polyester oligomer which is subsequently subjected to polycondensation at a pressure of 0.005 bar at a temperature of 275-300 to obtain a polycondensation product which upon solidification and drying is subjected to solid-state polycondensation at a temperature of 200-220 C. under a vacuum of 20 for a period of 5-50 hours.

[0069] Aspect 12: Foam comprising the thermoplastic polyester copolymer according to any of aspects 1-10.

[0070] Aspect 13: Foam according to aspect 12 having a density of <100 kg/m.sup.3as determined in accordance with ASTM D6226 (2010).

[0071] Aspect 14: Foam according to any of aspects 12-13 having an open cell content of 15.0% as determined in accordance with ASTM D6226 (2010).

[0072] Aspect 15: Process for the production of a foam according to any one of aspects 12-14 via an extrusion moulding process comprising a first twin-screw melt extruder and a second single-screw melt extruder positioned in series, wherein a feed composition comprising the thermoplastic polyester copolymer according to any one of claims 1-10 is introduced to the feed inlet of the first twin-screw melt extruder, wherein a quantity of a blowing agent is introduced to the first twin-screw melt extruder, and wherein the molten composition comprising the thermoplastic polyester copolymer and the blowing agent upon exiting the twin-screw melt extruder is fed to the feed inlet of the single-screw melt extruder and extruder from the single-screw melt extruder through a die to form a foam.

[0073] The invention will now be illustrated by the following non-limiting examples.

[0074] A poly(ethylene terephthalate) copolymer was produced via a process involving first a melt polymerisation stage and a subsequent solid state polymerisation stage.

[0075] The melt polymerisation was performed as a batch reaction in a reaction vessel having a volume sufficient to produce 50 kg of PET copolymer per batch.

[0076] A formulation of raw materials according to the table below was introduced into the reaction vessel:

TABLE-US-00001 TABLE I raw material formulation Quantity in view Compound CAS reg. nr. of PET formed Formulation 1 Terephthalic acid 100-21-0 43.3 kg Monoethylene 107-21-1 20.8 kg glycol Antimony 6923-52-0 275 ppm of Sb in 34.20 g triacetate PET Pentaerythritol 115-77-5 250 ppm in PET 12.50 g Cobalt acetate 6147-53-1 16 ppm of Co in 3.40 g tetrahydrate PET

[0077] The temperature inside the reaction vessel was increased to 250 C. such that esterification occurs. Pressure during esterification was set at 4.0 bar with gradual reduction to 1.0 bar during the course of the reaction, which was allowed to proceed for between 2 and 3 hours. The water formed during esterification was removed and the obtained PET oligomeric product was placed in a second reaction vessel for polycondensation. A quantity of further additives was added to the second reaction vessel according to table II.

TABLE-US-00002 TABLE II additives for polycondensation Quantity in view Compound CAS reg. nr. of PET formed Formulation 1 Zinc acetate dihydrate 5970-45-6 25 ppm of Zn in 4.25 g PET Triethyl phosphate 78-40-0 20 ppm of P in 5.87 g PET

[0078] The temperature was increased to 280 C. and polycondensation was performed at a pressure of 2.0 mbar under continuous agitation of the reaction vessel. Polycondensation was performed under continuous removal of monoethylene glycol until target torque achievement. After completion of the polycondensation reaction, the polymeric product was pumped out of the reactor and extruded through a die plate to form polymer strands, which were cooled to solidify in a water bath and cut to form granules of amorphous PET copolymer having a diameter of 2-5 mm.

[0079] The granules were further subjected to solid state polymerisation (SSP). The granules were fed into a tumble drier acting as SSP reactor. The temperature was increased to 160 C. and maintained for 2 hrs to remove moisture, under continuous agitation and under continuous nitrogen flow. Subsequently the SSP reaction was performed by increasing the temperature to 205 C. and applying a vacuum of 1 mbar under continuous agitation. SSP was performed for a period of 26 hours to obtain a PET copolymer having an intrinsic viscosity of 1.0 dl/g as determined in accordance with ASTM D2857-95 (2007).

[0080] The PET copolymer of formulation 1 as obtained via the method described above (further also referred to as CoPET-1) and commercial PET homopolymers were further processed into foamed materials in a number of examples with varying quantities of a chain extender compound Masspet 2834NF, a PET masterbatch comprising 50 wt % of a chain extender, obtainable from Point Plastics Srl. of Italy. Formulations of compounded examples are presented in table III below.

[0081] The foamed materials were produced using a tandem foam line comprising a twin screw Berstorff ZE40 extruder in series with a single screw Berstorff KE90 extruder. Formulations according to table III were fed to the twin screw extruder for mixing, where the material exiting the twin screw extruder were fed to the single screw extruder for cooling. The twin screw extruder was operated at a temperature profile of 50 C. at the feed section up to 300 C. at the outlet. The speed of the twin screw extruder was set at 135 rpm, and material throughput was 70 kg/h. The cyclopentane blowing agent was introduced in the twin screw extruder.

[0082] The temperature profile of the single screw extruder was from 80 C. at the material inlet to 250 C. at the die outlet. Speed of the single screw extruder was set at 10 rpm.

[0083] A slit die at the outlet of the single screw extruder having a die gap of 2.5 mm and a width of 180 mm was used to produce foam sheets. A die with 3 rows of holes where each row 17 holes each of 8 mm diameter, the holes distributed over a width of 180 mm, was used to produce foam boards. Upon exiting the die, the foamed materials were cooled.

TABLE-US-00003 TABLE III compounding formulations. Example CoPET-1 BC112 HS088 Masspet CP 1 98.8 1.2 4.43 2 98.5 1.5 4.43 3 98.2 1.8 4.43 4 98.5 1.5 3.13 5 98.4 1.6 3.13 6 98.2 1.8 3.13 7 100.0 4.43 8 97.5 2.5 3.0 9 97.5 2.5 4.0 10 97.5 2.5 4.43 11 97.5 2.5 5.0 12 100.0 4.43 13 100.0 3.13 14 97.5 2.5 3.13 15 97.3 2.7 3.38 16 100.0 3.13 17 97.5 3.13 18 97.3 3.38 19 100.0 3.13

[0084] The quantities in table III indicate parts by weight. BC 112 is a PET homopolymer having an intrinsic viscosity of 0.8 dl/g. HC088 is a PET homopolymer having an intrinsic viscosity of 0.92 dl/g. Both are obtainable from SABIC. CP is cyclopentane, Examples 1-6 reflect the invention, examples 7-19 are presented for comparative purposes.

[0085] Of the foamed materials prepared according to the formulations of table III, a number of properties were determined as presented below in table IV.

TABLE-US-00004 TABLE IV properties of foamed materials. Foam density Open cell Average foam Fmax at 80% Example Foamable (kg/m.sup.3) fraction (%) thickness (mm) strain (MPa) 1 Y 60 29 26.3 0.64 2 Y 54 5.8 28.8 0.64 3 Y 61 22.6 27.6 0.70 4 Y 87 0.02 3.04 1.66 5 Y 71 10.8 4.15 1.44 6 Y 90 0.02 2.54 1.84 7 N 8 Y 79 6.4 23.2 1.20 9 Y 81 4.4 24.8 1.20 10 Y 55 12.3 25.2 0.63 11 Y 56 28.8 25.6 0.55 12 N 13 N 14 Y 117 5.4 2.40 2.70 15 Y 73 9.3 2.48 1.80 16 N 17 Y 111 15.6 2.50 2.90 18 Y 101 0.12 3.38 1.95 19 N

[0086] Foamability indicated the ability to produce a foamed material according to the formulation of the particular example. Table IV shows that the formulations of examples 7, 13 and 16 (commercial PET homopolymers) as well as 12 and 19 (PET copolymers according to the invention, no branching agent added) did not allow for the production of any foamed material.

[0087] The foam density and the fraction of open cells were determined using a pycnometer in accordance with ASTM D6226 (2010). The compressive strength (Fnnax) was determined in accordance with ASTM D1621 (2010) using a Zwick tensile tester where the samples were stacks of 5 foam sheets or boards each having a diameter of 4 cm.

[0088] In examples 1-3 and 8-11, foam boards were produced according to the method for producing foam boards as presented above. In examples 4-6, 14-15 and 17-18 foam sheets were produced according to the method for producing foam sheets as presented above. The average foam thickness for those examples reflects the board or sheet thickness, whatever applicable.

[0089] The above examples show that using the PET copolymers according to the present invention, at given quantity of blowing agent, the quantity of chain extender that needs to be used to produce a foam material of desired properties is far less than would in the case where commercial homopolymer PET materials are used that do not contain units derived from a compound according to formula I, such as pentaerythritol, as do the PET copolymers of the present invention.