Use of polyamide 6 (PA6) as a heat-aging stabilizer in polymer compositions comprising polyphenylene sulfide (PPS)

Abstract

The present invention relates to a polymer composition comprising polyphenylene sulphide (PPS), polyamide 6 (PA6), reinforcing agents, wherein the weight ratio of PPS/PA6 is at least 2, with the proviso that the composition does not comprise an elastomer or comprises an elastomer in an amount not exceeding 1 wt. %. The present invention also relates to articles incorporating the polymer composition and the use of polyamide 6 (PA6) as a heat-aging stabilizer in a polymer composition.

Claims

1. A polymer composition comprising: 35 to 70 wt. % of a polyphenylene sulfide (PPS), wherein the polyphenylene sulfide (PPS) has a weight average molecular weight of 30,000 to 70,000 g/mol, 5 to 14 wt. % of polyamide 6 (PA6), 25 to 60 wt. % of reinforcing agents, 0 to 5 wt. % of an optional component selected from the group consisting of plasticizers, colorants, pigments, antistatic agents, dyes, lubricants, thermal stabilizers, light stabilizers, flame retardants, nucleating agents and antioxidants, wherein the weight ratio PPS/PA6 is at least 2.5 and not more than about 14, with the proviso that the composition does not comprise an elastomer or comprises an elastomer in an amount not exceeding 1 wt. %, wherein wt. % are based on the total weight of the composition.

2. The polymer composition of claim 1, wherein the PPS comprises at least about 50 mol. % of recurring units (R.sub.PPS) of formula (L): ##STR00004## wherein R.sub.1 and R.sub.2, equal to or different from each other, are selected from the group consisting of hydrogen atoms, halogen atoms, C.sub.1-C.sub.12 alkyl groups, C.sub.7-C.sub.24 alkylaryl groups, C.sub.7-C.sub.24 aralkyl groups, C.sub.6-C.sub.24 arylene groups, C.sub.1-C.sub.12 alkoxy groups, and C.sub.6-C.sub.18 aryloxy groups, and substituted or unsubstituted arylene sulfide groups, wherein mol. % is based on the total number of moles in the PPS.

3. The polymer composition of claim 1, wherein the PA6 comprises at least about 50 mol. % of recurring units (R.sub.PA6) of formula (N): —NH—(CH.sub.2).sub.5—CO— wherein mol. % is based on the total number of moles in the PA6.

4. The polymer composition of claim 1, wherein the weight ratio of PPS/PA6 is at least 3.

5. A method of making the polymer composition of claim 1, wherein the method comprises melt-blending PPS, PA6, and the reinforcing agents, and optionally any other components.

6. An article comprising the polymer composition of claim 1.

7. The article of claim 6, wherein the article is a film, a laminate, an automotive part, an engine part, an electrical part, or an electronic part.

8. A method of heat-stabilizing a polymer composition comprising; adding from 5 to 14 wt. % of polyamide 6 (PA6) as a heat-aging stabilizer in the polymer composition comprising: 35 to 70 wt. % of a polyphenylene sulfide (PPS), wherein the polyphenylene sulfide (PPS) has a weight average molecular weight of 30,000 to 70,000 g/mol, 25 to 60 wt. % of reinforcing agents, 0 to 5 wt. % of an optional component selected from the group consisting of plasticizers, colorants, pigments, antistatic agents, dyes, lubricants, thermal stabilizers, light stabilizers, flame retardants, nucleating agents and antioxidants, wherein the weight ratio PPS/PA6 is at least 2.5 and not more than about 14, with the proviso that the composition either does not comprise an elastomer orcomprises an elastomer in an amount not exceeding 1 wt. %, wherein wt. % are based on the total weight of the composition.

9. The method of claim 8, wherein the PA6 comprises at least about 50 mol. % of recurring units (R.sub.PA6) of formula (N): —NH—(CH.sub.2).sub.5—CO— wherein mol. % is based on the total number of moles in the PA6.

10. The method of claim 8, wherein the weight ratio of PPS/PA6 is at least 3.

11. The polymer composition of claim 1, wherein the weight ratio of PPS/PA6 is at least 4.

12. The polymer composition of claim 1, wherein the weight ratio of PPS/PA6 is at least 5.

13. The method of claim 8, wherein the weight ratio of PPS/PA6 is at least 4.

14. The method of claim 8, wherein the weight ratio of PPS/PA6 is at least 5.

15. A polymer composition consisting of: 35 to 70 wt. % of a polyphenylene sulfide (PPS), 5 to 14 wt. % of polyamide 6 (PA6), 25 to 60 wt. % of reinforcing agents, 0 to 5 wt. % of an optional component selected from the group consisting of plasticizers, colorants, pigments, antistatic agents, dyes, lubricants, thermal stabilizers, light stabilizers, flame retardants, nucleating agents and antioxidants, wherein the weight ratio PPS/PA6 is at least 2.5 and not more than about 14, with the proviso that the composition does not comprise an elastomer or comprises an elastomer in an amount not exceeding 1 wt. %, wherein wt. % are based on the total weight of the composition.

Description

EXAMPLES

(1) Raw Materials

(2) PPS Ryton® QA281 N (Solvay)

(3) PA 6 AK270 (Shaw Industries)

(4) Glass Fibers T779H (Nippon)

(5) Lotader@ AX8840 (Arkema), copolymer of ethylene and glycidyl methacrylate (epoxy functionalized)

(6) Irganox® 1010 (BASF), an antioxidant

(7) HDPE (High Density Polyethylene) 6007G (Chevron Phillips), a lubricant

(8) Compounding

(9) Compounding that involved the incorporation of glass fibers was performed on a Coperion ZSK-26 R&D twin-screw extruder (26 mm extruder). The neat PPS resin was fed into barrel 1. Glass fibers were fed at barrel 7. Optional ingredients when present were also included into barrel 1, possibly pre-mixed before being fed into barrel 1.

(10) Barrel conditions were specified in order to achieve a melt temperature between 310° C. and 340° C. Screw speeds were set at 200 RPM. Feed rates were set according to the desired composition of each formulation.

(11) The molten strands were cooled and crystallized in a water bath before being pelletized for further processing.

(12) Molding

(13) All compounds were molded into ISO Type IA tensile bars.

(14) Testing

(15) Tensile properties were tested according to ISO 527-2 using the ISO Type IA tensile bars.

(16) Heat aging was performed by exposing test samples in an air oven regulated at 200° C. and removed after designated time intervals, to be subsequently tested at room temperature for tensile properties.

(17) The components and their respective amounts in the compositions (according to the present invention or comparative) and the mechanical properties of the same are reported in Table 1 below.

(18) Example

(19) TABLE-US-00001 TABLE 1 1 C1 C2 Components (wt. %) PPS 59.25 69.25 63.25 PA6 10 — — Glass Fibers 30 30 30 Lotader ® AX8840 — — 6 HDPE 6007G 0.25 0.25 0.25 Irganox ® 1010 0.5 0.5 0.5 Tensile properties and Heat aging Stability Tensile Modulus (MPa) 11700 ± 173  12200 ± 164  10800 ± 311  Tensile Strain at break  1.7 ± 0.05  1.4 ± 0.04  2.1 ± 0.06 (%) Tensile Stress at break  163 ± 3.67  152 ± 2.85  164 ± 4.31 (MPa) T0 Tensile stress at break  149 ± 2.35  131 ± 5.01  138 ± 2.73 (MPa) T1 = 1000 hours at 200° C. Heat aging-Tensile 91.4 86.2 84.1 Strength at break Retention (%)

(20) The presence of PA6 in Example 1 results in a favourable balance of tensile properties (i.e. stiffness as measured by Tensile Modulus; Tensile Strain at break; and tensile strength as measured by Tensile Stress at break at T0) in comparison to the same composition incorporating no PA6 (comparative example C1) or the same composition incorporating no elastomer (comparative example C2).

(21) Example 1, according to the invention, provides better heat aging stability (i.e. tensile strength retention of 91.4% as measured with tensile strength after 1000 hours at 200° C.), as compared to comparative examples C1 and C2.

(22) Due to a higher value of heat aging resistance, Example 1 exhibits an even higher tensile stress value after heat aging (Tensile Stress at break at T1) than compared to comparative examples C1 and C2.