Method for stabilizing halogen-free thermoplastic recyclates, stabilized plastic compositions, and molding compounds and molded parts produced therefrom

Abstract

The invention relates to a method for stabilizing halogen-free thermoplastic recyclates or pre-damaged plastics against oxidative, thermal, and/or actinic degradation. In the method according to the invention, at least one alditol or cyclitol is introduced into a halogen-free thermoplastic recyclate as a component, and optionally in addition thereto, at least one primary antioxidant and/or at least one secondary antioxidant is introduced into a halogen-free thermoplastic recyclate. By virtue of the method according to the invention, plastic recyclates can be stabilized against oxidative, thermal, and/or actinic degradation with a high degree of effectiveness and in a very environmentally friendly and inexpensive manner. The invention additionally relates to corresponding recyclate-based plastic compositions, to molding compound and molded parts produced therefrom, to stabilizer compositions, and to the use thereof for stabilizing halogen-free thermoplastic recyclates against oxidative, thermal, and/or actinic degradation.

Claims

1. A method for stabilizing a halogen-free thermoplastic recyclate against oxidative, thermal, and/or actinic degradation comprising introducing at least one alditol selected from isomaltol, lactitol, maltotriol, threitol, erythritol, galactol, mannitol, ribitol, xylitol, arabitol, hydrated oligosaccharides, and polysaccharides with polyol end groups, (component (A)), into the halogen-free thermoplastic recyclate, wherein the halogen-free thermoplastic recyclate is selected from a recycled polymer of an olefin, a diolefins, and a mixture thereof, and further comprising introducing at least one primary antioxidant and/or at least one secondary antioxidant (component (B)) into the halogen-free thermoplastic recyclate.

2. The method of claim 1, wherein the at least one primary antioxidant is selected from phenolic antioxidants, amines, and lactones.

3. The method of claim 1, wherein the at least one secondary antioxidant is selected from phosphorus compounds and organo-sulfur compounds.

4. The method of claim 1, wherein the at least one alditol is selected from threitol, erythritol, galactol, mannitol, ribitol, xylitol, arabitol, hydrated oligosaccharides, and polysaccharides with polyol end groups.

5. The method of claim 1, wherein the at least one primary antioxidant and the at least one secondary antioxidant are introduced into the halogen-free thermoplastic recyclate.

6. The method of claim 1, wherein component (A) and component (B) are introduced into the halogen-free thermoplastic recyclate in a weight ratio of 95:5 to 5:95.

7. The method of claim 1, wherein components (A) and (B) are introduced into the halogen-free thermoplastic recyclate such that components (A) and (B) present as solids are mixed with the halogen-free thermoplastic recyclate present as a solid and the mixture thereby produced is melted and subsequently cooled; or components (A) and (B) present as solids are melted and the melt thus produced is introduced into a melt of the halogen-free thermoplastic recyclate.

8. The method of claim 1, wherein 0.01 to 5.0 parts by weight of the at least one alditol (component A) are introduced with respect to 95.0 to 99.99 parts by weight of the halogen-free thermoplastic recyclate.

9. The method of claim 1, wherein, with respect to 91 to 99.94 parts by weight of the halogen-free thermoplastic recyclate, (A) 0.02 to 3 parts by weight of the at least one alditol; and (B) 0.04 to 6 parts by weight of the at least one primary antioxidant and/or of the at least one secondary antioxidant are introduced.

10. The method of claim 1, wherein the recycled polymer of olefin or diolefin is selected from: a) polyethylene, polypropylene, polyisobutylene, poly-4-methyl-pentene-1, polybutadiene, polyisoprene, polycyclooctene, polyalkylene-carbon monoxide copolymers, and corresponding copolymers in the form of statistical or block structures, ethylene-vinyl acetate (EVA), ethylene-acrylic ester polymers, polypropylene-g-maleic acid anhydride, polypropylene-g-acrylic acid, and polyethylene-g-acrylic acid, and b) mixtures, combinations, and blends of two or more of the above-named polymers.

11. A plastic composition comprising at least one alditol, wherein the at least one alditol is selected from isomaltol, lactitol, maltotriol, threitol, erythritol, galactol, mannitol, ribitol, xylitol, arabitol, hydrated oligosaccharides, and polysaccharides with polyol end groups, (component (A)); at least one primary antioxidant and/or at least one secondary antioxidant (component (B)); and at least one halogen-free thermoplastic recyclate, wherein the halogen-free thermoplastic recyclate is selected from a recycled polymer of an olefin or diolefin.

12. The plastic composition of claim 11, wherein the plastic composition comprises (A) 0.01 to 5.0 parts by weight of the at least one alditol, and (B) 95.0 to 99.99 of the at least one halogen-free thermoplastic recyclate.

13. The plastic composition of claim 11, which comprises: the at least one alditol (component (A)); the at least one primary antioxidant and/or at least one secondary antioxidant (Component (B)); and the at least one halogen-free thermoplastic recyclate.

14. The plastic composition of claim 11, wherein the plastic composition comprises: 0.02 to 3 parts by weight of the at least one alditol, 0.04 to 6 parts by weight of the at least one primary antioxidant and/or of the at least one secondary antioxidant, and 91 to 99.94 parts by weight of the at least one halogen-free thermoplastic recyclate.

15. The plastic composition of claim 13, wherein the plastic composition comprises: (A) 0.02 to 3 parts by weight of the at least one alditol, (B1) 0.02 to 3 parts by weight of the at least one primary antioxidant, (B2) 0.02 to 3 parts by weight of the at least one secondary antioxidant, and (C) 91 to 99.94 parts by weight of the at least one halogen-free thermoplastic recyclate.

16. The plastic composition of claim 12, further comprising at least one additive selected from 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, optical brighteners, antimicrobial active agents, antistatic agents, slip agents, anti-blocking agents, coupling agents, crosslinking agents, anti-cross-linking agents, hydrophilization agents, hydrophobing agents, anchoring agents, dispersing agents, compatibilizers, oxygen scavengers, acid scavengers, expanding agents, degradation additives, defoaming agents, odor scavengers, marking agents, anti-fogging agents, fillers, and reinforcement materials.

17. The plastic composition of claim 12, which further comprises at least one additive selected from acid scavengers, light stabilizers, dispersing agents, and filler deactivators.

18. The plastic composition of claim 12, which is manufactured by a method which comprises stabilizing a halogen-free thermoplastic recyclate against oxidative, thermal, and/or actinic degradation comprising introducing the at least one alditol (component (A)) into the halogen-free thermoplastic recyclate.

19. A molding compound or a molded part manufactured from the plastic composition of claim 11.

Description

(1) In the following examples in accordance with the invention, the effect of different alditols/cyclitols is shown in combination with a primary and a secondary antioxidant in different concentrations and the effect in a post-consumer recyclate is shown.

(2) Table 3: A polypropylene recyclate (pre-damaged, manufactured by aging Moplen HP 500 N (supplier: Lyondell-Basell) at 140° C. in a convection oven for 32 days is conveyed in a circle in the melt together with the additives shown in the table at 200° C. in a twin screw micro-extruder (MC 5, manufacturer DSM) in a continuous mode at 90 revolutions per minute for 30 minutes. The force absorption is measured in each case after 10, 20, and 30 minutes. The force is a measure for the toughness of the melt and thus for the molecular weight. The higher the remaining force (after a melting time of 2 minutes=100%), the smaller the degradation of the polymer and the better the stabilization effect.

(3) TABLE-US-00003 TABLE 3 Remaining Remaining Remaining force in force in force in % after % after % after Post-stabilization 10 minutes 20 minutes 30 minutes Comparison Without additive 77 60 43 example 4 Example 2 in 0.1% erythritol + 85 74 62 accordance 0.05% AO-1 + with the 0.05% P-1 invention Example 3 in 0.2% erythritol + 94 84 72 accordance 0.05% AO-1 + with the 0.05% P-1 invention Example 4 in 0.1% myo-inositol + 88 78 68 accordance 0.05% AO-1 + with the 0.05% P-1 invention Example 5 in 0.1% isomaltol + 82 67 55 accordance 0.05% AO-1 + with the 0.05% P-1 invention

(4) The examples in accordance with the invention here have higher forces at all measurement times, i.e. a smaller degradation of the polymer than the comparison example.

(5) Table 4: A post-consumer polypropylene recyclate from accumulator box ground stock (supplier: BSB Braubach) is conveyed in a circle in the melt together with the additives shown in the table at 215° C. in a twin screw micro-extruder (MC 5, manufacturer DSM) in a continuous mode at 90 revolutions per minute for 30 minutes. The force absorption is measured in each case after 10, 20, and 30 minutes. The force is a measure for the toughness of the melt and thus for the molecular weight. The higher the remaining force (after a melting time of 2 minutes=100%), the smaller the degradation of the polymer and the better the stabilization effect.

(6) TABLE-US-00004 TABLE 4 Remaining Remaining Remaining force in force in force in % after % after % after Post-stabilization 10 minutes 20 minutes 30 minutes Comparison Without additive 70 47 27 example 4 Comparison 0.05% AO-1 + 0.05% 80 62 50 example 6 P-1 + 0.3% AS-1 Comparison 0.1% AO-1 + 0.1% 86 71 58 example 7 P-1 + 0.3% AS-1 Comparison 0.3% AS-1 78 55 35 example 8 Example 6 in 0.1% erythritol + 96 73 65 accordance 0.05% AO-1 + 0.05% with the P-1 + 0.3% AS-1 invention Example 7 in 0.2% erythritol + 96 88 67 accordance 0.05% AO-1 + 0.05% with the P-1 + 0.3% AS-1 invention Example 8 in 0.1% myo-inositol + 90 78 69 accordance 0.05% AO-1 + 0.05% with the P-1 + 0.3% AS-1 invention Example 9 in 0.1% isomaltol + 94 79 69 accordance 0.05% AO-1 + 0.05% with the P-1 + 0.3% AS-1 invention AS-1 = Hycite 713 (manufacturer: Clariant SE) is a hydrotalcite used as an acid captor.

(7) The examples in accordance with the invention here have higher forces at all measurement times, i.e. a smaller degradation of the polymer than the comparison example.

(8) In the following example (Table 5) in accordance with the invention, the stabilization of a recyclate by an alditol alone is shown analogously to the processing conditions of Table 3.

(9) TABLE-US-00005 TABLE 5 Remaining Remaining Remaining force in force in force in % after % after % after Post-stabilization 10 minutes 20 minutes 30 minutes Comparison Without additive 77 60 43 example 4 (from Table 3) Example 11 in 0.2% erythritol 83 61 46 accordance with the invention

(10) The examples in accordance with the invention here have higher forces at all measurement times, i.e. a smaller degradation of the polymer than the comparison example.

(11) In the following example (Table 6) in accordance with the invention, the stabilization of a recyclate by an alditol without an antioxidant is shown analogously to the processing conditions of Table 4.

(12) TABLE-US-00006 TABLE 6 Remaining Remaining Remaining force in force in force in % after % after % after Post-stabilization 10 minutes 20 minutes 30 minutes Comparison Without additive 70 47 27 example 5 (from Table 4) Example 12 in 0.1% myo-inositol + 82 69 57 accordance 0.3% AS-1 with the invention

(13) The example in accordance with the invention here has higher forces at all measurement times, i.e. a smaller degradation of the polymer than the comparison example.

(14) The post-consumer accumulator box recyclate was then extruded three times at a maximum temperature of 230° C. by means of a twin screw extruder of the type Process 11 (Fisher Scientific) at 200 r.p.m., cooled in a water bath, and subsequently pelletized, and the MVR was determined in each case after the 1st, 2nd, and 3rd extrusion (Table 7). The lower the MVR, the smaller the degradation of the polymer in the processing and the better the stabilization effect.

(15) TABLE-US-00007 TABLE 7 After the After the After the 1st 2nd 3rd extrusion extrusion extrusion MVR MVR MVR Post-stabilization (230/2.16) (230/2.16) (230/2.16) Comparison Without additive 9.6 10.2 11.4 example 6 Example 13 in 0.2% mannitol + 9.2 9.3 9.2 accordance with 0.2% AS-1 the invention Example 14 in 0.1% mannitol + 8.4 8.8 8.5 accordance with 0.1% tannin + the invention 0.2% AS-1 Example 15 in 0.2% mannitol + 8.2 8.4 8.5 accordance with 0.2% tannin + the invention 0.2% AS-1

(16) The examples in accordance with the invention here have a smaller MVR value, i.e. a smaller degradation and thus an improved stability than the comparison example, after all extrusions.

(17) In a further experimental series polypropylene recyclate (pre-damaged, manufactured by aging Moplen HP 500 N (supplier: Lyondell-Basell) at 140° C. in a convection oven for 32 days was conveyed in a circle in the melt together with the additives shown in the table at 200° C. in a twin screw micro-extruder (MC 5, manufacturer DSM) in a continuous mode at 90 revolutions per minute for 30 minutes and the percentage residual stability was determined with reference to the remaining force (Table 8). The force is a measure for the toughness of the melt and thus for the molecular weight. The higher the remaining force at the end of the experiment, the smaller the degradation of the polymer and the better the stabilization effect.

(18) TABLE-US-00008 TABLE 8 Remaining force in N after 30 Post-stabilization minutes Comparison example 7 0.05% AO-1 + 0.05% P-1 310 Comparison example 8 0.1% AO-1 + 0.1% P-1 390 Comparison example 9 0.1% P-1 350 Example 16 in accordance 0.05% AO-1 + 0.05% P-1 + 520 with the invention 0.05% mannitol Example 17 in accordance 0.05% AO-1 + 0.05% P-1 + 680 with the invention 0.1% mannitol Example 18 in accordance 0.05% AO-1 + 0.05% P-1 + 640 with the invention 0.2% mannitol Example 19 in accordance 0.1% AO-1 + 0.1% mannitol 580 with the invention Example 20 in accordance 0.1% P-1 + 0.1% mannitol 560 with the invention Example 21 in accordance 0.1% mannitol 410 with the invention Example 22 in accordance 0.5% mannitol 470 with the invention

(19) The examples in accordance with the invention here have a higher residual force i.e. a smaller degradation of the polymer than the comparison examples.

(20) In an analogous manner to polypropylene recyclate, post-consumer polyethylene recyclates from packaging films, primarily comprising LDPE and LLDPE, polyethylene recyclates from hollow bodies, primarily comprising HDPE, polystyrene recyclates from packaging foams, polyamide-6-recyclates from electrical applications, and PET recyclates from beverage bottles were each provided with the additives in accordance with the invention and extruded. An improved stability in comparison with the recyclates without an additive can be found in all cases.