POLYMER COMPOSITION, MOLDED PART AND PROCESSES FOR PRODUCTION THEREOF

Abstract

The present invention relates to a polymer composition, consisting of (A) polymer comprising at least (A-1) a first semi-crystalline semi-aromatic polyamide (SSPA); and (A-2) a functionalized polymer; (B) 5-69 wt. % of reinforcing agent; and (C) 0-25 wt. % of one or more other components; wherein the SSPA is present in an amount in the range of 30-90 wt. %; has a melting temperature (Tm) of at least 300 C., measured by DSC according to ISO-11357-1/3, 2011 with heating and cooling rate of 10 C./min; and consists of: (A-1-a) 90-100 mole % of repeat units derived from (i) aromatic dicarboxylic acid and (ii) diamines, and (A-1-b) 0-10 mole % of repeat units derived from other monomers; and the diamines (ii) consist of 80-95 mole % of linear aliphatic diamine, 5-20 mole % of 2-methyl-pentamethylene diamine, and 0-10 mole % of other diamines; wherein the functionalized polymer (A-2) comprises a functionalized semi-crystalline polyolefin in an amount of 1-15 wt. %; and wherein the weight percentages (wt. %) of components (A), (B) and (C) and of SSPA and the functionalized semi-crystalline polyolefme are relative to the total weight of the composition, while the sum of (A), (B) and (C) is 100 wt. %. The invention further relates to a molded part made of the composition, a process for making the composition and a process for making the molded part.

Claims

1. Polymer composition, consisting of: (A) polymer comprising at least (A-1) a first semi-crystalline semi-aromatic polyamide (SSPA); and (A-2) a functionalized polymer; (B) 5-69 wt. % of reinforcing agent; and (C) 0-25 wt. % of one or more other components; wherein the SSPA is present in an amount in the range of 30-90 wt. %; has a melting temperature (Tm) of at least 300 C., measured by DSC according to ISO-11357-1/3, 2011 with heating and cooling rate of 10 C./min; and consists of: (A-1-a) 90-100 mole % of repeat units derived from (i) aromatic dicarboxylic acid and (ii) diamines, and (A-1-b) 0-10 mole % of repeat units derived from other monomers; and the diamines (ii) consist of 80-95 mole % of linear aliphatic diamine, 5-20 mole % of 2-methyl-pentamethylene diamine, and 0-10 mole % of other diamines; wherein the functionalized polymer (A-2) comprises a functionalized semi-crystalline polyolefin in an amount of 1-15 wt. %; and wherein the weight percentages (wt. %) of components (A), (B) and (C) and of SSPA and the functionalized semi-crystalline polyolefine are relative to the total weight of the composition, while the sum of (A), (B) and (C) is 100 wt. %.

2. Polymer composition according to claim 1, wherein the SSPA has a melting temperature in the range of 310-350 C.

3. Polymer composition according to claim 1, wherein the aromatic dicarboxylic acid is selected from terephthalic acid, 2,6-naphthalene dicarboxylic acid and 4,4-biphenyl dicarboxylic acid, or a combination thereof, and preferably is terephthalic acid.

4. Polymer composition according to claim 1, wherein the diamines (ii) consist of 5-15 mole % of 2-methyl-pentamethylene diamine, 85-95 mole % of a linear aliphatic diamine, and 0-5 mole % of other diamines.

5. Polymer composition according to claim 1, wherein the diamines comprise 40-95 mole % of a linear C2-C8 diamine, more preferably 60-95 mole % of a linear C4-C6 diamine, relative to the total molar amounts of diamines.

6. Polymer composition according to claim 1, wherein the functionalized semi-crystalline polyolefin is present in an amount in the range of 2-10 wt. %, relative to the total weight of the composition.

7. Polymer composition according to claim 1, wherein the functionalized semi-crystalline polyolefin comprises, and preferably consists of a maleic anhydride-functionalized polyethylene, a maleic anhydride-functionalized polypropylene or a maleic anhydride-functionalized ethylene-propylene copolymer, or any mixture thereof.

8. Polymer composition according to claim 1, wherein component (B) comprises glass fibers or carbon fibers, or a mixture thereof.

9. Polymer composition according to claim 1, wherein component (B) is present in an amount in the range of 10-50 wt. %, relative to the total weight of the composition.

10. Process for preparing a polymer composition according to claim 1, comprising the steps of: (1) providing polymer comprising at least (A-1) a first semi-crystalline semi-aromatic polyamide (SSPA), and (A-2) a functionalized semi-crystalline polyolefin; reinforcing agent, and optionally one or more other components, and (2) melt-mixing the said components in the following amounts: (A) the polymer comprising 30-90 wt. % of the first semi-crystalline semi-aromatic polyamide (SSPA) 1-15 wt. % of the functionalized semi-crystalline polyolefin; (B) 5-69 wt. % of the least one reinforcing agent; (C) 0-25 wt. % of the one or more other components; wherein the SSPA: has a melting temperature (Tm) of at least 300 C.; and consists of: (A-1-a) 90-100 mole % of repeat units derived from (i) aromatic dicarboxylic acid and (ii) diamines, and (A-1-b) 0-10 mole % of repeat units derived from other monomers; and the diamines (ii) consist of 80-95 mole % of linear aliphatic diamine, 5-20 mole % of 2-methyl-pentamethylene diamine, and 0-10 mole % of other diamines; and wherein the weight percentages (wt. %) of components (A), (B) and (C) and of SSPA and the functionalized semi-crystalline polyolefine are relative to the total weight of the composition, while the sum of (A), (B) and (C) is 100 wt. %.

11. Process according claim 10, wherein the polymer composition is a composition.

12. Molded part made of, or comprising an element made of a polymer composition claim 1.

13. Molded part according to claim 12, wherein the molded part is an automotive part, or a part of an electronic device.

14. Molded part according to claim 12, wherein the molded part or the element comprised by the molded part, is a multi-gate injection molded part

15. Process for making a molded part comprising a step comprising injection molding of a polymer composition into a mold, wherein the polymer composition is a polymer composition according to claim 1.

16. Process according to claim 15, wherein the mold is a mold with a multi-gate cavity.

Description

Materials

[0115] PA-6T/4T/DT copolymer (58/32/10 molar ratio) made by DSM. The polyamide consists of repeat units derived from respectively: 1,6-hexanediamine and terephthalic acid (abbreviated as 6T), 1,4-butanediamine and terephthalic acid (abbreviated as 4T), and 2-methyl-pentamethylene diamine and terephthalic acid (abbreviated as DT).

[0116] Functionalized polyolefine: EXXELOR VA 1801 maleic anhydride modified semi-crystalline polyethylene copolymer comprising about 0.6 weight percent pendant succinic anhydride groups (commercially available from ExxonMobil Chemical Company).

Compounding

[0117] Polyamide compositions were prepared on a twin-screw extruder, employing standard molding conditions. The temperature of the extruded melt was typically about 350-360 C. After the melt compounding the resulting melt was extruded into strands, cooled and cut into granules.

Injection MoldingPreparation of Test Bars for Mechanical Testing

[0118] Dried granulate material was injection molded into a mold to form test bars conforming ISO 527 type 1A; the thickness of the test bars was 4 mm. The polyamide compositions were injection molded into appropriate test molds using a standard injection molding machine. Test bars were prepared using either a single gated mold for standard test bars or a double gated mold for production of test bars with a weld line, each gate located at an opposite end of the sample and causing the formation of a weld line, while applying the same conditions as for the standard test bars. The setting temperature of the T-melt in the injection molding machine was about 350 C.; the temperature of the mold was 140 C.

Testing

Melting Temperature (Tm)

[0119] The measurements of the melting temperature (Tm) were carried out with a Mettler Toledo Star System (DSC) using a heating and cooling rate of 10 C./min. in an N2 atmosphere. For the measurements a sample of about 5 mg pre-dried powdered polymer was used. The pre-drying was carried out at high vacuum, i.e less than 50 mbar and a 130 C. during 16 hrs. The sample was heated from 0 C. to a temperature about 30 C. above the melting temperature at 10 C./min, immediately cooled to 0 C. at 10 C./min and subsequently heated to about 30 C. above the melting temperature again at 10 C./min. For the melting temperature Tm the peak value of the melting peak in the second heating cycle was determined, according to the method of ISO-11357-113, 2011.

Tensile Strength

[0120] The tensile strength was measured in a tensile test according to ISO 527/1 at 150 C., at a drawing speed of 5 mm/min.

Weldline Strength

[0121] The weldline strength was measured in a tensile test according to ISO 527/1 at 23 C., at a drawing speed of 5 mm/min.

[0122] The compositions and test results have been summarized in Table 1.

TABLE-US-00001 TABLE 1 Compositions and properties of Example I and Comparative Experiment A CE-A EX-I Composition (wt. %) PA-6T/4T/DT (58/32/10) 84.7 79.7 Glass fibers 15 15 Functionalized Polyolefine 0 5 Additive package (ST + MRA) 0.3 0.3 Properties.sup.a) Tm ( C.) 342 337 Tensile strength at 120 C. [MPa] 90.1 106.5 Elongation at break at 120 C. (%) 1.43 2.6 Weldline strength at 23 C. [MPa] 33.8 75.2 Weldline Elongation at break at 23 C. (%) 0.56 1.42 .sup.a)Mechanical properties measured on samples with a thickness of 4 mm.

[0123] The results show significantly increased properties for the compositions according to the invention, compared to corresponding compositions not comprising the functionalized semi-crystalline polyolefin, both for the weldline properties measured at room temperature and for the mechanical properties measured at elevated temperature. This result, obtained with relatively thin samples made from a polymer composition comprising the copolyamide and the functionalized polyolefin as according to the invention, is highly surprising and in contrast with the known compositions of U.S. Pat. No. 6,306,951-B1, comprising a succinic anhydride functionalized blockCopolymer comprising polymerized styrene blocks and polyolefin blocks. The compositions of U.S. Pat. No. 6,306,951-B1 did not show any serious effect of the functionalized polymer on the mechanical properties of thin samples (thickness 0.125 inch or 3.2 mm) measured at room temperature, neither for the mechanical properties as such, nor for the properties measured on samples with weldlines.