THERMOPLASTIC COMPOUNDS CONTAINING RECYCLING MATERIAL WITH SUPERIOR QUALITY

Abstract

The invention relates to thermoplastic molding compositions (T) comprising 10 to 99% by weight, based on the total weight of the molding composition (T), of at least one type of recycled polymer material (A), containing 20 to 100% by weight, based on recycled material (A), of recycled acrylonitrile-butadiene-styrene copolymer (A1); up to 80% by weight of at least one recycled styrene-acrylonitrile copolymer (A2); up to 10% by weight of recycled polymeric impurities (A3), different from (A1) and (A2); 0.1 to 30% by weight, based on the total weight of the molding composition (T), of at least one graft copolymer (B), different from (A); 0.1 to 18% by weight, based on the molding composition (T), of block copolymer (C); and optionally up to 89.8% by weight of further polymer component (D), different from (A), (B) and (C); optionally up to 30% by weight of filler and/or reinforcing agent (E); and optionally up to 30% by weight of further additive (F).

Claims

1-15. (canceled)

16. A thermoplastic molding composition (T) comprising: A 10 to 99% by weight, based on the total weight of the thermoplastic molding composition (T), of at least one type of recycled polymer material (A), containing A1 20 to 100% by weight, based on the total weight of the recycled material (A), of at least one recycled acrylonitrile-butadiene-styrene copolymer (A1); A2 optionally up to 80% by weight, based on the total weight of the recycled material (A), of at least one recycled styrene-acrylonitrile copolymer (A2); and A3 optionally up to 10% by weight, based on the total weight of the recycled material (A), of recycled polymeric impurities (A3), different from (A1) and (A2); B 0.1 to 30% by weight, based on the total weight of the thermoplastic molding composition (T), of at least one graft copolymer (B), different from (A); C 0.1 to 18% by weight, based on the total weight of the thermoplastic molding composition (T), of at least one block copolymer (C); D optionally up to 89.8% by weight, based on the total weight of the thermoplastic molding composition (T), of at least one further polymer component (D), different from (A), (B), and (C); E optionally up to 30% by weight, based on the total weight of the thermoplastic molding composition (T), of at least one filler and/or reinforcing agent (E); and F optionally up to 30% by weight, based on the total weight of the thermoplastic molding composition (T), of at least one further additive (F).

17. The thermoplastic molding composition (T) of claim 16, comprising: A 50 to 98% by weight, based on the total weight of the thermoplastic molding composition (T), of the at least one recycled material (A); B 1 to 20% by weight, based on the total weight of the thermoplastic molding composition (T), of the at least one graft copolymer (B); C 1 to 15% by weight, based on the total weight of the thermoplastic molding composition (T), of the at least one block copolymer (C); D optionally up to 48% by weight, based on the total weight of the thermoplastic molding composition (T), of at least one further polymer component (D); E optionally up to 25% by weight, based on the total weight of the thermoplastic molding composition (T), of at least one filler and/or reinforcing agent (E); and F optionally up to 10% by weight, based on the total weight of the thermoplastic molding composition (T), of at least one further additive (F).

18. The thermoplastic molding composition (T) of claim 16, wherein the at least one graft copolymer (B) comprises at least one acrylonitrile-butadiene-styrene graft copolymer.

19. The thermoplastic molding composition (T) of claim 18, wherein the at least one graft copolymer (B) consists of at least one acrylonitrile-butadiene-styrene graft copolymer.

20. The thermoplastic molding composition (T) of claim 16, wherein the at least one graft copolymer (B) comprises at least one acrylonitrile-butadiene-styrene graft copolymer (B), which is obtained by emulsion polymerization.

21. The thermoplastic molding composition (T) of claim 16, wherein the at least one block copolymer (C) comprises at least one block copolymer of a vinyl-aromatic monomer and a diene monomer.

22. The thermoplastic molding composition (T) of claim 21, wherein the at least one block copolymer (C) consists of at least one block copolymer of a vinyl-aromatic monomer and a diene monomer.

23. The thermoplastic molding composition (T) of claim 21, wherein the at least one block copolymer (C) comprises at least one styrene-butadiene copolymer.

24. The thermoplastic molding composition (T) of claim 16, wherein the at least one block copolymer (C) has at least three types of blocks.

25. The thermoplastic molding composition (T) of claim 16, wherein the terminal blocks of the at least one block copolymer (C) are derived from a vinyl-aromatic monomer.

26. The thermoplastic molding composition (T) of claim 25, wherein the terminal blocks of the at least one block copolymer (C) are derived from styrene.

27. The thermoplastic molding composition (T) of claim 16, wherein the at least one recycled material (A) is obtained from post-consumer waste.

28. The thermoplastic molding composition (T) of claim 16, wherein the at least one further polymer component (D) is present in an amount of at least 0.5% by weight, based on the total weight of the thermoplastic molding composition (T), and comprises at least one styrene-acrylonitrile copolymer, at least one poly(methyl (meth)acrylate), at least one styrene-methyl (meth)acrylate copolymer, at least one polycarbonate, at least one polystyrene, or a combination of two or more thereof.

29. The thermoplastic molding composition (T) of claim 28, wherein the at least one further polymer component (D) consists of at least one styrene-acrylonitrile copolymer, at least one poly(methyl (meth)acrylate), at least one styrene-methyl (meth)acrylate copolymer, at least one polycarbonate, at least one polystyrene, or a combination of two or more thereof.

30. The thermoplastic molding composition (T) of claim 16, wherein no further polymer component (D) is present.

31. The thermoplastic molding composition (T) of claim 16, wherein the weight ratio of the at least one graft copolymer (B) to the at least one block copolymer (C) is from 1:3 to 3:1.

32. The thermoplastic molding composition (T) of claim 31, wherein the weight ratio of the at least one graft copolymer (B) to the at least one block copolymer (C) is from 1:1.2 to 1.2:1.

33. A process for preparing a thermoplastic molding composition (T) of claim 16, wherein the components (A), (B), (C), optionally (D), optionally (E), and optionally (F) are melt compounded at a temperature in the range of 180 to 280° C.

34. The process of claim 33, wherein solid inorganic impurities are removed from the at least one recycled material (A) prior to the melt compounding.

35. A shaped article prepared from the thermoplastic molding composition (T) of claim 16.

Description

EXAMPLES

Physical Testing of Products:

[0102] Charpy-impact strength was tested at 23° C. or −10° C. at (50±5)% r.h. (relative humidity) according to ISO 179/1eA (notched) on bars molded at a mass temperature of 250° C. and a mold temperature of 80° C. If not stated otherwise, the unit is kJ/m.sup.2.

[0103] Melt flow rate or melt viscosity rate (MVR) was determined on a polymer melt at 220° C. with a load of 10 kg according to ISO 1133-1:2012. If not stated otherwise, the unit is mL/10 min.

[0104] Tensile strain at yield (elongation) was measured at 23° C. at (50±5)% r.h. according to ISO 527/1996 on specimens molded at a mass temperature of 250° C. and a mold temperature of 80° C. Speed of measurement was 50 mm/min.

Recycled Polymer Material (A)

[0105] As recycled polymer material (A), a recycled post-consumer waste was used (WEEE; Waste of Electrical and Electronic Equipment, according to European Community Directive 2012/19/EU).

[0106] The material was black from using carbon black as main pigment and small amounts of other colorants. The material was not sorted by color, but only by the type of polymers.

[0107] The sorted flakes have been compounded in order to level performance of the material. Furthermore, a melt sieve has been used in order to remove un-melted (mostly inorganic) contaminations. The remaining ash content in the recycled polymer material was 1% by weight, based on the weight of the recycled polymer material (A) (complete combustion).

[0108] Mass ratio of the monomers acrylonitrile, butadiene and styrene was 23:15:62 (as measured by IR spectroscopy).

[0109] The content of acrylonitrile-butadiene-styrene copolymer was 34% by weight, based on the total weight of polymeric components in (A) and the content of acrylonitrile-styrene copolymer was 64% by weight, based on the total weight of polymeric components in (A). Other polymeric impurities were present in an amount of 1.5% by weight, based on the total weight of polymeric components in (A), wherein the main impurity was high impact polystyrene (HIPS).

[0110] As a non-polymeric impurity, the recycled material (A) contained 2.1% by weight, based on the total weight of the recycled material (A), of EBS wax (CAS 110-30-5).

Graft Copolymer (B)

[0111] ABS graft rubber produced in radically initiated (potassium persulfate) emulsion polymerization in two polymerization steps. 5 kg of butadiene was first polymerized in the presence of demineralized water, 100 g anionic emulsifier, 25 g 2,3,3,4,4,5-hexamethylhexane-2-thiol (technical mixture containing also other isomers) and 15 g potassium peroxodisulfate at temperatures around 70° C. over a period of 20 hr. The resultant particle size was 100 nm and solid content of the latex about 45 wt %. A second batch was prepared with a polymerization time of 2 days by polymerizing 5 kg of butadiene in the presence of demineralized water, 40 g anionic emulsifier, 45 g 2,3,3,4,4,5-hexamethylhexane-2-thiol (technical mixture containing also other isomers) and 20 mg potassium peroxodisulfate at temperatures around 70° C. and a resulting particle size of 290 nm and solid content of the latex about 50 wt %. A third polymerization batch was prepared with a polymerization time of 4 days by polymerizing 5 kg of butadiene in the presence of demineralized water, 30 g anionic emulsifier, 30 g 2,3,3,4,4,5-hexamethylhexane-2-thiol (technical mixture containing also other isomers) and 25 g potassium peroxodisulfate at temperatures around 80° C. and a resulting particle size of 400 nm and solid content of the latex about 50 wt %.

[0112] 3 kg of the first polybutadiene-latex (solids) was grafted with 740 g acrylonitrile and 2.1 kg styrene under addition of 80 g anionic emulsifier, 6 g 2,3,3,4,4,5-hexamethylhexane-2-thiol (technical mixture containing also other isomers) and 30 mg potassium peroxodisulfate at temperatures from 60 to 80° C. (increase over three hours) over five hours. 3 kg of the mixture of the second and third polybutadine lattices (1:1 by weight solids) were grafted with 0.5 kg acrylonitrile and 1.5 kg styrene under addition of 70 g anionic emulsifier, 6 g 2,3,3,4,4,5-hexamethylhexane-2-thiol (technical mixture containing also other isomers) and 25 g potassium peroxodisulfate at temperatures from 60 to 80° C. (increase over three hours) over five hours. 5 kg of the former graft latex (solids) were mixed with κ kg of the latter graft latex (solids) and a stabilizer dispersion containing a hindered phenol and a sulfur synergist.

[0113] The resulting latex was precipitated by adding MgSO.sub.4 electrolyte at temperatures between 60 and 90° C., mechanically dewatered and afterwards dried for 10 h in a well ventilated oven at 60°. The graft polymer B was obtained as fine, dry powder with a residual moisture content of 0.2% by weight.

Block Copolymer (C)

[0114] In a batch reactor (stainless steel reactor, stirred, 50 m.sup.3) 20500 L of cyclohexane at 40° C. was used as initial charge and 1,344 L styrene (S1) was added at 20 m.sup.3/h. When 134 L of S1 had been dosed, 46.43 L of a 1.4 M sec-butyllithium solution (BuLi 1) for initiation and 6.03 L of a 5 wt % potassium tert-amylate solution in cyclohexane as randomizer had been dosed at once. The reaction was allowed to proceed under continuous stirring to complete monomer consumption (identified by no further temperature increase of the reaction mixture). After complete monomer consumption, the polymerization mixture was cooled by means of reflux cooling to a temperature below 65° C.

[0115] In a next step, 924 L styrene (S2) and 1,439 L butadiene (B1) were added together and the polymerization reaction, under continuous stirring, was allowed to run to complete monomer consumption (identified by no further temperature increase of the reaction mixture). After complete monomer consumption, the polymerization mixture was cooled by means of reflux cooling to a temperature below 48° C.

[0116] In a next step, 1,193 L of styrene (S3) and 1,857 L of butadiene (B2) were added together and the polymerization reaction, under continuous stirring, was allowed to run to complete monomer consumption (identified by no further temperature increase of the reaction mixture). After complete monomer consumption, the polymerization mixture was cooled by means of reflux cooling to a temperature below 65° C. In a next step, 655 L styrene (S4) and 1,020 L butadiene (B3) were added together and the polymerization reaction, under continuous stirring, was allowed to run to complete monomer consumption (identified by no further temperature increase of the reaction mixture). After complete monomer consumption, the polymerization mixture was cooled by means of reflux cooling to a temperature below 65° C. In a next step, 1,344 L styrene (S5) was added and the polymerization reaction, under continuous stirring, was allowed to run to complete monomer consumption (identified by no further temperature increase of the reaction mixture).

[0117] 10 minutes after the last complete monomer consumption, 9.5 L isopropanol was added to the polymer solution and allowed to react for 10 minutes while stirring. Finally, the reaction mixture was stabilized by acidification with 0.06 phm* demineralized water and a 0.43 phm CO.sub.2 gas stream and stabilized with 0.15 phm Sumilizer® GS, 0.20 phm Irganox® 1010 and 0.15 phm Irgaphos® 168 in a continuous fashion using a static mixer.

[0118] *phm=“parts by weight per hundred parts by weight of monomer” (wt.-% of component (initiator, coupling agent etc.) is calculated on the total mass of the monomers).

[0119] Finally, the cyclohexane solvent was removed by means of a flash evaporization followed by a degassing extruder and under water palletization to obtain the styrene-butadiene block-copolymer granulate.

[0120] All compounds mentioned in the tables below have been produced on a ZSK twin screw extruder with 3 kneading blocks typical for ABS compounding, maximum melt temperature was 250° C. and torque was about 70%.

[0121] As can be seen from table 1, at a content of 90% by weight of recycled polymer material (A), addition of 5% by weight of graft copolymer (B) and 5% by weight of block copolymer (C) (example 1) gives a better property profile than addition of 10% by weight of graft copolymer (B) alone (comparative example 1) or addition of 10% by weight of block copolymer (C) alone (comparative example 2). For comparative example 1, Charpy notched impact strength increases significantly, yet MVR decreases significantly in comparison to the recycled polymer material (A) alone (reference example). For comparative example 2, MVR increases significantly, but Charpy notched impact strength increases to a lesser extent than in comparative example 1. The combination of both graft copolymer (B) and block copolymer (C) (example 1) results in higher Charpy notched impact strength than in both comparative examples, and a significant increase in MVR. In all cases, a slight increase of tensile strain at yield (elongation) was observed in comparison to reference example.

[0122] At a content of 80% by weight of the recycled polymer material (A), addition of 20% by weight of block-copolymer (C) does not lead to a stable composition that can be evaluated. Addition of 20% by weight of graft copolymer (B) leads to a significant increase of Charpy notched impact strength, but also to a significant deterioration of MVR (comparative example 3). In comparison, addition of 15% by weight of graft copolymer (B) and 5% by weight of block copolymer (C) leads to an even greater increase of Charpy notched impact strength, whereas MVR deteriorates to a much lesser extent (example 2). The addition of 10% by weight of graft copolymer (B) and 10% by weight of block copolymer (C) also leads to an increase of Charpy notched impact strength over comparative example 3, and an even more pronounced increase of MVR (example 3).

[0123] In all cases, a slight increase of tensile strain at yield (elongation) was observed in comparison to the recycled polymer material (A) without the graft copolymer (B) and the block copolymer (C) (reference example).

TABLE-US-00001 TABLE 1 Ref. Comp. Comp. Ex. Comp. Ex. Ex. Ingredient Ex. Ex. 1 Ex. 2 1 Ex. 3 2 3 (A) [% by weight] 100 90 90 90 80 80 80 (B) [% by weight] 0 10 0 5 20 15 10 (C) [% by weight] 0 0 10 5 0 5 10 MVR 220/10 26.0 22.5 44.4 31.1 15.4 23.1 35.4 [mL/10 min] Charpy notched 8.2 13.3 12.1 13.6 17 22 24 impact strength (23° C.) [kJ/m.sup.2] Charpy notched 5.8 7.5 6.7 7.4 9.8 10.4 9.9 impact strength (−10° C.) [kJ/m.sup.2] Tensile strain 2.2 2.3 2.5 2.4 2.4 2.5 2.6 at yield (elongation) [%]

[0124] As it can be seen, the thermoplastic molding compositions comprising high amounts of (A) and comprising ABS component (B) and comprising SBC-component (C) had a particularly good balance of properties, in particular Charpy impact strength and tensile strain at yield.