Polyamide composition

Abstract

The invention pertains to a filled polyamide composition [composition (C)] comprising: from 35 to 80% wt of at least one polyhydric alcohol-modified polyamide, comprising an amount of polyhydric alcohol (PHA, herein after) residues chemically bonded at least to a part of the polyamide [polyamide (A)] of at least 0.1% wt (based on the total weight of polyamide (A)); from 10 to 65% wt of at least one filler [filler (F)]; from 1 to 10% wt of at least one impact modifying rubber [rubber (I)]; and from 0.01 to 3% wt of at least one copper-containing stabilizer, with above % wt being referred to the total weight of composition (C).

Claims

1. A filled polyamide composition comprising, based on the total weight of the composition: from 50 to 70% wt of at least one polyhydric alcohol-modified polyamide, said polyhydric alcohol-modified polyamide comprising an amount of at least 0.1% wt and at most 10% wt, based on the total weight of the polyhydric alcohol-modified polyamide, of polyhydric alcohol residues chemically bonded at least to a part of the polyhydric alcohol-modified polyamide, wherein said polyhydric alcohol is an organic compound containing three or more hydroxyl groups in the molecule and is selected from dipentaerythritol and tripentaerythritol; from 15 to 50% wt of at least one filler comprising glass fibers; from 3 to 6% wt of at least one impact modifying rubber comprising ethylene amorphous copolymers grafted with maleic anhydride; and from 0.01 to 3% wt of at least one copper-containing stabilizer, wherein the copper-containing stabilizer provides 75 to 150 ppm copper to the filled polyamide composition, wherein the polyamide is polyamide 6,6.

2. The composition of claim 1, wherein the polyhydric alcohol-modified polyamide is obtained by condensation reaction in the presence of the at least one polyhydric alcohol, of a monomer mixture of adipic acid and 1,6-diaminohexane; wherein the amount of polyhydric alcohol used in the condensation reaction is from 0.15 to 20% wt, based on the total weight of the at least one monomer mixture.

3. The composition of claim 1, wherein the polyhydric alcohol-modified polyamide has a content of chemically bonded polyhydric alcohol residues of at least 0.5% wt, and at most 10% wt, based on the total weight of the polyhydric alcohol-modified polyamide.

4. The composition of claim 1, wherein the polyhydric alcohol-modified polyamide comprises non-chemically bonded polyhydric alcohol in an amount of less than 2% wt, based on the total weight of the polyhydric alcohol-modified polyamide.

5. The composition of claim 1, wherein the copper-containing stabilizer comprises a copper compound and an alkali metal halide in a weight ratio of copper compound:alkali metal halide of from 1:99 to 30:70.

6. The composition of claim 1, further comprising a co-stabilizer selected from the group consisting of hindered amine compounds, hindered phenol compounds, and phosphorous compounds.

7. A method of making the composition according to claim 1, said method comprising melt-blending the polyhydric alcohol-modified polyamide, the filler, the rubber, the copper-containing stabilizer, and of any other optional ingredient.

8. A method for manufacturing an article, comprising shaping the composition of claim 1 by a shaping technique selected from the group consisting of extrusion, injection moulding, thermoform moulding, compression moulding and blow moulding.

9. The method according to claim 8, wherein the article is selected from the group consisting of films, laminates, automotive parts, engine parts, electrical parts, and electronics parts.

10. The method according to claim 8, wherein the article is suitable for high temperature applications.

11. The composition of claim 3, wherein the polyhydric alcohol-modified polyamide comprises from 0.75% wt to 7% wt chemically bonded polyhydric alcohol residues, based on the total weight of the polyhydric alcohol-modified polyamide.

12. The composition of claim 4, wherein the polyhydric alcohol-modified polyamide comprises less than 1.5% wt non-chemically bonded polyhydric alcohol, based on the total weight of the polyhydric alcohol-modified polyamide.

13. The composition claim 5, wherein the weight ratio of copper compound:alkali metal halide is from 5:95 to 20:80.

Description

PREPARATIVE EXAMPLESGENERAL POLYMERIZATION PROCEDURE

(1) In a batch reactor were introduced the required amount of Nylon 66 salt (hexamethylene diammonium adipate), water and anti-foaming agent Silcolapse 5020, in combination with appropriate amount of PHA and, when used, of additional monomers, and possibly of a hypophosphite catalyst. The polyamide was synthesized according to a standard process for the synthesis of PA 66, followed by a finishing step in conditions specified below. The polymer was then extruded under the shape of a strand, cooled in a cold water bath and pelletized to get pellets.

(2) Ingredients and polymerization conditions are summarized in table 6 herein below.

(3) TABLE-US-00006 TABLE 6 Example CPE1 PE1 PE2 PE3 Nylon66 salt (kg) 80.0 92.56 92.56 92.56 DPE(*) (kg) 2.47 2.51 TPE(*) (kg) 2.47 Adipic acid (kg) 0.71 0.48 1.73 Water (kg) 72.8 84.2 84.2 89.0 NaH.sub.2PO.sub.2 (ppm P) 20 20 Anti-foaming agent (g) 5.5 6.4 6.4 6.4 Finishing temp. ( C.) 275 275 275 275 Finishing pressure (bar) 1 0.5 0.5 1 Finishing time (min) 30 22 12 37 IV (mL/g) 137.5 109.2 116.3 139.2 CEG (meq/kg) N.M. 70.3 77.7 121.4 AEG (meq/kg) N.M. 54.7 62 35.4 Tm ( C.) 262 N.M. N.M. 255 Hm (J/g) 67 N.M. N.M. 55 Chemically bonded PHA 2.2 2.26 2.75 content (wt.-%) Free PHA content (wt.-%) 0.8 0.73 0.25 (*)DPE: dipentaerythritol; TPE: tripentaerythritol.

(4) General Procedure for Extrusion of Compounds and High Heat Long Term Ageing Testing

(5) Before extrusion, pellets of the polyamides were dried to decrease water content below 1500 ppm. The compositions were obtained by melt blending of the selected ingredients in a WERNER&PLEIFEDER ZSK 40 twin-screw extruder using the following parameters: 35 kg/hour, 280 rounds per minute, 8 heating zone set-points: 250, 255, 260, 260, 265, 270, 275, 280 C. All ingredients were fed at the beginning of the extruder. The extruded strand was cooled in a water bath, then pelletized and the obtained pellets were stored into sealed aluminium line bags to prevent moisture adsorption.

(6) The polyamides manufactured as above specified were compounded with following ingredients: Stabamid 26AE2 PA66, which is a polyamide 66 commercially available from Solvay (IV=134 mL/g), having more carboxylic acids than amino end groups; Vetrotex OCV 983 Glass fibers from Owens Corning; Lubricant ethylene-bis-stereamide; Exxelor VA1803 from ExxonMobil, which is an amorphous ethylene copolymer functionalized with maleic anhydride by reactive extrusion; CuI and KI from AJAY Europe;

(7) The compositions were injection-molded using a DEMAG 50T injection molding machine at 290 C. with a mold temperature of 80 C. to prepare 4 mm thick ISO527 samples. Before ageing, initial mechanical properties (E-modulus, tensile strength (TS) at break and strain at break) were determined by tensile measurements according to ISO 527/1A at 23 C., as average values from 5 specimens.

(8) The samples were heat aged in a re-circulating air oven (Heraeus TK62120) set at 210 C. At various heat ageing times (500 h, 1000 h and 2000 h), the samples were removed from the oven, allowed to cool to room temperature and placed into sealed aluminium lined bags until ready for testing. Mechanical properties were measured according to the same procedure as before ageing.

(9) The retention of a mechanical property (tensile strength at break, E-modulus, strain at break) is expressed as the percentage of the ratio of the value of the mechanical property after a certain heat ageing time at the temperature T and the value of the mechanical property before ageing. For example, for a heat ageing time of 500 h at T, retention (TS) is expressed as percentage of TS(500 h,T)/TS(initial).

(10) The ingredients and their reciprocal amounts in the compositions and the mechanical properties of the samples before and after air oven ageing are reported in Tables below.

(11) TABLE-US-00007 TABLE 8 CE1 CE2 CE3 CE4 E1 CE5 Ingredients PA 66 wt % 59.25 64.7 PE1 wt % 61 60.7 PE2 wt % 61 PE3 wt % 64.1 Glass fibers wt % 35 35 35 35 35 35 Lubricant wt % 0.3 0.3 Black wt % 0.3 0.3 VA1803 wt % 4 4 4 4 CuI/KI wt % 0.15/1 0.04/0.26 0.04/0.26 0.04/0.26 Cu (ppm) 500 133 0 0 133 133 Compounds properties Free PHA 0.49 N.M. N.M. N.M. content (wt.-%).sup.(#) Bonded 1.38 N.M. N.M. N.M. PHA content (wt.-%).sup.(#) TM (MPa) 11570 11800 11700 11800 11900 11780 TS.sub.B (MPa) 189 211 205 206 208 212 TE.sub.B (%) 2.73 3.1 2.9 3.1 2.8 2.8 Heat ageing at 210 C. TS.sub.B/R.sub.500 h N.M. 153/73 202/99 204/89 201/97 N.M. (MPa)/(%) TS.sub.B/R.sub.1000 h 116/62 108/51 171/84 162/79 173/83 155/74 (MPa)/(%) TS.sub.B/R.sub.2000 h 45/24 20/9 56/27 70/34 138/66 72/34 (MPa)/(%) TM (MPa): Tensile modulus; TS.sub.B (MPa): Tensile strength at break; TE.sub.B (%): Tensile strain (or elongation) at break; TS.sub.B/R.sub.500 h: TS.sub.B (MPa)/retention (%) after 210 C. 500 h; TS.sub.B/R.sub.1000 h: TS.sub.B (MPa)/retention (%) after 210 C. 1000 h; TS.sub.B/R.sub.2000 h: TS.sub.B (MPa)/retention (%) after 210 C. 2000 h. .sup.(#)PHA (bonded/free) content with respect to the overall composition weight

(12) As the examples clearly demonstrated, only the combination of copper-containing stabilizer and rubber (I) in a PHA-modified polyamide have enabled achieving retention up to more than 65% of mechanical properties after heat ageing at 210 C. for as long as 2000 h.