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. 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.

2. 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. 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 3.0 wt %.

4. Polyamide composition according to claim 1, wherein E1 is chosen from the group of Benzenepropanoic 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) Phenol, 4,44-[(2,4,6-trimethyl-1,3,5-benzenetriyl)-tris-(methylene)]-tris-2,6-bis(1,1-dimethylethyl)- 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 3-(3,5-Di-t-butyl-4-hydroxy-phenyl) propion acid ester with 1,3,5-tris (2-hydroxy-ethyl)-iso-cyanurate.

5. Polyamide composition according to claim 1, wherein the ratio primary antioxidant group:hindered amine is at least 1:1.5 in which the ratio is based on weight percentages based on E1 and E2; if the primary antioxidant group and the hindered amine group are present as E3 or a combination of E1, E2, and E3, the ratio is calculated by the number of primary antioxidant group:number of hindered amine group.

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

7. Polyamide composition according to claim 1, wherein the semi-crystalline polyamide is chosen from the group of PA-6, PA-66, PA6/66, PA66/6, PA-410 and blends thereof.

8. Polyamide composition according to claim 1, wherein the inorganic stabilizer is a copper compound and a salt containing a halogenide acid group.

9. Polyamide composition according to claim 1, wherein E1 is a hindered phenolic antioxidant.

10. 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.

11. Polyamide composition according to claim 1, wherein the composition further comprises a nucleating agent.

12. Process for preparing a container, comprising at least the following steps: a. heating a polyamide composition according to claim 1, to obtain a viscous liquid; b. forming a parison from the viscous liquid; c. expand the parison by pressurized gas and press it against a mold cavity until it cools and solidifies to form a container; d. opening the mold; e. ejecting the container.

13. A blow molded container prepared by blow molding a polyamide composition according to claim 1.

14. Blow molded container according to claim 13, 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>2WD.

15. Use of the blow molded container according to claim 13 as a fuel tank, a compressed natural gas tank, a hydrogen tank, a duct or a chemical storage container.

Description

EXAMPLES

Melt Volume Flow Rate (MVR)

[0240] 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.

Impact Falling Dart Test

[0241] 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.

[0242] 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.

[0243] 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.

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

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

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

[0244] 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.

[0245] 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.

[0246] 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.