Heat stabilized polyamide composition

Abstract

The invention relates to a polyamide composition comprising: a. A semi-crystalline polyamide; b. An impact modifier in an amount ranging from 1 wt % to 50 wt %; c. A branching agent in an amount ranging from 0.01 to 6.0 wt %; d. An inorganic stabilizer in an amount ranging from 0.01 wt % to 2.0 wt %; e. An organic stabilizer E1 comprising a primary antioxidant group in an amount ranging from 0.01 wt % to 2.0 wt and an organic stabilizer E2 comprising a hindered amine group in an amount ranging from 0.01 wt % to 4.0 wt %; or an organic stabilizer E3 comprising a primary antioxidant group and a hindered amine group in an amount ranging from 0.02 to 6.0 wt %; or a combination of E1, E2 and E3 in a total amount of 0.02 to 6.0 wt %; wherein all wt % are based on the total amount of polyamide composition. The invention also relates to a process for preparing a container by blow molding this composition, as well as use of the container in various applications.

Claims

1. A polyamide composition comprising: (a) a semi-crystalline aliphatic polyamide selected from the group consisting of PA-6, PA-66, PA6/66, PA66/6, PA-410 and blends thereof; (b) 5 to 50 wt. % of functionalized olefinic rubber having a Tg of lower than 0° C. and containing groups reactive with the polyamide (a) as an impact modifier; (c) 0.03 to 3.0 wt. % of a branching agent having functional groups that are capable of reacting with amino, amide and/or carboxylic end-groups of the polyamide (a); (d) 0.01 to 2.0 wt. % of a copper compound and a salt containing a halogenide acid group or a copper complex as an inorganic stabilizer; and (e) a combination of an organic stabilizer E1 in an amount ranging from 0.1 wt % to 2.0 wt % and an organic stabilizer E2 in an amount ranging from 0.1 wt % to 2.0 wt %; wherein the organic stabilizer E1 comprises a primary antioxidant group which is a phenolic antioxidant, and the organic stabilizer E2 comprises a hindered amine group derived from a substituted piperidine compound, and wherein all wt % are based on the total amount of polyamide composition, and wherein a blow molded part formed of the polyamide composition after heat aging at 200° C. exhibits at least 30 J of energy by an impact falling dart test according to ISO 6603-2 after 20 minutes, 200 minutes and 1000 minutes.

2. The polyamide composition according to claim 1, wherein the polyamide composition has a melt volume flow rate ranging from 25 to 45 cm.sup.3/10 min, as measured according to ISO 1133 with 21.6 kg and 275° C.

3. The polyamide composition according to claim 1, wherein E1 is present in an amount ranging from 0.1 wt % to 1.0 wt % and E2 is present in an amount ranging from 0.1 wt % to 2.0 wt %, or E3 is present in an amount ranging from 0.2 to 3.0 wt %, or a combination of E1, E2 and E3 is present in a total amount ranging from 0.2 to 0 wt %.

4. The polyamide composition according to claim 1, wherein E1 is selected chosen from the group consisting of: benzenpropanoic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxy-octadecyl ester; 2,5,7,8-Tetra-methyl-2-(4′,8′,12′-tri-methyl-tri-decyl)-chroman-6-ol; N,N″-hexamethylene bis (3,5-di-t-butyl-4-hydroxyhydrocinnamamide); ethylenebis(oxyethylene) bis (3-t-butyl-4-hydroxy-5-methylhydrocinnamate); hexamethylenebis (3,5-di-t-butyl-4-hydroxycinnamate); 4,4′,4″-[(2,4,6-trimethyl-1,3,5-benzenetriyl)tris(methylene)]tris[2,6-bis(1,1-dimethylethyl)-phenol; bis-[3,3-bis-(4″-hydroxy-3″-t-butylphenyl butanoic acid]-glycol ester: tris(3,5-di-t-butyl-4-hydroxy benzyl) isocyanurate; tetrakis[methylene (3,5-di-t-butyl-4-hydroxyhydrocinnamate)] methane; and 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid ester with 1,3,5-tris (2-hydroxy-ethyl)-iso-cyanurate.

5. The polyamide composition according to claim 1, wherein a ratio E1:E2 is at least 1:1.5, wherein the ratio is based on weight percentages of total weights of E1 and E2.

6. The polyamide composition according to claim 1, wherein the composition is free of phosphites.

7. The polyamide composition according to claim 1, wherein E1 is a hindered phenolic antioxidant.

8. The polyamide composition according to claim 1, wherein the composition further comprises a silicone oil in an amount of at least 50 ppm with respect to the total amount of composition.

9. The polyamide composition according to claim 1, wherein the composition further comprises a nucleating agent.

10. A blow molded container prepared by blow molding a polyamide composition according to claim 1, wherein after heat aging at 200° C., the blow molded container exhibits at least 30 J of energy by an impact falling dart test according to ISO 6603-2 after 20 minutes, 200 minutes and 1000 minutes.

11. The blow molded container according to claim 10, wherein the container has a length L, a width W and a depth D as defined in a 3 dimensional Cartesian coordinate system, wherein L is at least 75 cm, and in which L>2W≥D.

12. The blow molded container according to claim 10, wherein the container is in a form selected from the group consisting of fuel tanks, compressed natural gas tanks, hydrogen tanks, ducts and chemical storage containers.

13. A polyamide composition comprising: (a) a semi-crystalline aliphatic polyamide selected from the group consisting of PA-6, PA-66, PA6/66, PA66/6, PA-410 and blends thereof; (b) 5 to 50 wt. % of functionalized olefinic rubber having a Tg of lower than 0° C. and containing groups reactive with the polyamide (a) as an impact modifier; (c) 0.03 to 3.0 wt. % of a branching agent having functional groups that are capable of reacting with amino, amide and/or carboxylic end-groups of the polyamide (a); (d) 0.01 to 2.0 wt. % of copper iodide and potassium bromide as inorganic stabilizers; and (e) a combination of an organic stabilizer E1 in an amount ranging from 0.1 wt % to 2.0 wt % and an organic stabilizer E2 in an amount ranging from 0.1 wt % to 2.0 wt %; wherein the organic stabilizer E1 comprises a primary antioxidant group which is a phenolic antioxidant, and wherein the organic stabilizer E2 comprises a hindered amine group derived from a substituted piperidine compound, and wherein all wt % are based on the total amount of polyamide composition, and wherein a blow molded part formed of the polyamide composition after heat aging at 200° C. exhibits at least 30 J of energy by an impact falling dart test according to ISO 6603-2 after 20 minutes, 200 minutes and 1000 minutes.

14. The polyamide composition according to claim 13, wherein the organic stabilizer E1 is present in an amount from 0.1 to 1.0 wt. %.

Description

(1) Examples

(2) Melt Volume Flow Rate (MVR)

(3) The MVR of the composition was measured according to ISO 1133 with a weight of 21.6 kg and at 275° C. prior to blow molding.

(4) Impact Falling Dart Test

(5) Impact falling dart test at −40° C. was performed on the plates using the guidelines ISO 6603-2. The diameter of the spherical falling dart was 20 mm and the mass of the falling dart was 23 kg. The test speed was 4.4 m/sec. At least five plates were tested. Plates of each material had been placed in a −40° C. freezer overnight prior to testing.

(6) Compositions were prepared by melt-mixing the ingredients as provided in Table 1 and 2; wt % are given for the compositions. These compositions were injection molded into test plates and exposed to 200° C. for a specified time. Plates from table 1 were exposed to 200° C. during 20 min, 200 min, 500 min and 1000 min respectively. Plates from table 2 were exposed to 200° C. during 200 min. After the specified exposure the plates were cooled and impact falling dart test was performed as specified above. Results are given in Table 1 and 2 as well.

(7) The results of table 1 clearly indicate that a composition comprising a semi-crystalline polyamide and an impact modifier and a branching agent and an inorganic stabilizer and organic stabilizer comprising a hindered phenolic antioxidant group and a hindered amine group, shows a synergistic effect. Example 1 shows high energy values for the falling dart test even after exposure of 1000 minutes at 200° C. In compositions were no organic stabilizer is present (Comparative B) or only one organic stabilizer (Comparative A) the energy values for the falling dart test decreased within 200 minutes. Also in the case where no inorganic stabilizer was present (Comparative C) or for a composition in which no impact modifier was present (Comparative D), the energy values for the falling weight test were insufficient. This clearly demonstrates that the composition which comprises an impact modifier, a branching agent and an inorganic stabilizer and an organic stabilizer based on both primary antioxidant and hindered amine show an synergistic effect in providing improved heat resistance, as measured by a falling weight test at 200° C.

(8) TABLE-US-00001 TABLE 1 Ex 1 Comp A Comp B Comp C Comp D Polymer PA6 75.56 76.21 76.54 76.04 98.55 Impact MAH grafted 22.79 22.79 22.79 22.79 modifier rubber Inorganic CuI/KBr 0.16 0.16 0.16 0.16 stabilizer Branching SMA/SAN/LDPE; 0.42 0.43 0.43 0.43 0.55 Agent 23.2/23.2/53.6 [wt %] Nucleating microtalcum 0.08 0.08 0.08 0.08 0.08 agent Organic PAO; Irganox 0.33 0.33 0.33 stabilizer 1098 Organic HAS; Hostavin 0.66 0.33 0.33 0.33 stabilizer N30 Total Energy −40° C. falling 37 38 37 39 18 weight test; [J]; 0 min  20 min @ 200° C. 55 53 49.8 57 12.6 200 min @ 200° C. 56 1 1.1 55 0.7 500 min @ 200° C. 46 1.8 1 1.1 0.9 1000 min @ 200° C.  38 2.3 4.3 3.2 2.2

(9) TABLE-US-00002 TABLE 2 Ex 2 Ex 3 Ex 4 Ex 5 Ex 6 Ex 7 Ex 8 Ex 9 Polymer PA6 75.97 75.97 75.97 75.97 75.97 76.42 76.47 76.32 Impact modifier MAH grafted rubber 22.79 22.79 22.79 22.79 22.79 22.34 22.22 22.22 Inorganic stabilizer CuI/KBr 0.07 0.07 0.07 0.07 0.07 0.08 0.15 0.30 Branching Agent SMA/SAN/LDPE; 0.43 0.43 0.43 0.43 0.43 0.42 0.42 0.42 23.2/23.2/53.6 [wt %] Nucleating agent microtalcum 0.08 0.08 0.08 0.08 0.08 0.08 0.08 0.08 Organic stabilizer PAO; Irganox 1098 0.33 0.33 0.33 0.33 0.33 0.33 Organic stabilizer PAO; Irganox 1010 0.33 0.33 Organic stabilizer HAS; Chimasorb 944 0.33 0.33 0.33 0.33 Organic stabilizer HAS; Hostavin N30 0.33 0.33 Organic stabilizer HAS; ADK STAB LA-63 0.33 0.33 Total Energy −40° C. falling weight test [J] 200 min @ 200° C. 57 56.2 57.8 58.4 56 43 46 45

(10) TABLE-US-00003 TABLE 3 Ex 10 Ex 11 Ex 12 Ex 13 Ex 14 Ex 15 Ex 16 Ex 17 Ex 18 Polymer PA6 75.89 75.56 75.40 74.90 75.89 75.89 75.90 63.59 63.59 Impact modifier MAH grafted rubber 22.79 22.79 22.79 22.79 22.79 22.79 22.79 34.82 34.82 Inorganic stabilizer CuI/KBr 0.16 0.16 0.32 0.16 0.16 0.16 0.16 0.16 Bruggolen H3387; 0.15 copper based antioxidant Branching Agent SMA/SAN/LDPE; 0.43 0.42 0.42 0.42 0.43 0.43 0.43 0.36 0.36 23.2/23.2/53.6 [wt %] Nucleating agent microtalcum 0.08 0.08 0.08 0.08 0.08 0.08 0.08 0.08 0.08 Organic stabilizer PAO; Irganox 1098 0.33 0.66 0.66 1.32 0.17 0.33 0.66 0.33 Organic stabilizer PAO; Irganox 1076 0.33 0.17 0.33 Organic stabilizer HAS; Hostavin N30 0.33 0.33 0.33 0.33 0.33 0.33 0.33 0.33 0.33 Total Energy −40° C. falling weight test [J] 200 min @ 200° C. 59 59 58 61 58 58 58 50 51 500 min @ 200° C. 60 60 58 51 57 59 58 54 54

(11) The results of Table 2 show that a combination with a semi-crystalline polyamide, an impact modifier, a branching agent and an inorganic stabilizer and a variety of organic stabilizers comprising primary antioxidant groups in combination with a variety of organic stabilizers comprising hindered amine groups also show a synergistic effect by providing high energy values for the falling dart test after being exposed for 200 minutes at 200° C.

(12) The compositions of examples 7 and 8 were blow molded into tanks. The MVR of these compositions were 36 cm.sup.3/10 min and 38 cm.sup.3/10 min respectively. The blow molded tanks were cut open and pinch lines were visually inspected. Sharp V-shape dents are an example of a bad pinch line quality. Good pinch lines show a smooth dent. The tanks of both example 7 and 8 showed a smooth dent and thus a good pinch line. Surprisingly, the inside of the tanks also exhibited less oxidation.

(13) The compositions in Table 3, all according to the invention, clearly show that with varying amounts of impact modifier (examples 17 and 18), or with other inorganic stabilizer (example 16) or with other organic stabilizer (examples 14 and 15), as well with varying amounts of stabilizers, all compositions exhibited a sufficient total energy of the falling dart test, even after exposure to 200° C. for 500 minutes.