MOLDING COMPOSITIONS REINFORCED WITH GLASS FIBERS HAVING IMPROVED IMPACT PROPERTIES

Abstract

A composition including: (A) from 29 to 74% by weight of at least one semi-crystalline aliphatic polyamide, the semi-crystalline aliphatic polyamide obtained from the polycondensation: of at least one C.sub.6 to C.sub.18 amino acid; or at least one C.sub.6 to C.sub.18 lactam; or at least one C.sub.4 to C.sub.36 diamine Ca with at least one C.sub.4 to C.sub.3 diacid Cb; (B) from 25 to 70% by weight of glass fibers mainly of silica dioxide (SiO2), aluminum oxide (Al2O3) and magnesium oxide (MgO); the glass fibers (B) having from 62 to 66% by weight of SiO2; (C) from 1 to 20% by weight of at least one impact modifier; and (D) from 0 to 2% by weight of at least one additive, excluding copper chromite, zinc sulfide, titanium dioxide, calcium carbonate and a polyolefin-based colored masterbatch; the sum of the various constituents (A) to (D) being 100% by weight.

Claims

1. A composition, particularly useful for injection molding, comprising: (A) from 29 to 74% by weight of at least one semi-crystalline aliphatic polyamide, said semi-crystalline aliphatic polyamide resulting from the polycondensation: of at least one C.sub.6 to C.sub.18, amino acid; or of at least one C.sub.6 to C.sub.18 lactam; or of at least one C.sub.4-C.sub.36 diamine Ca with at least one C.sub.4-C.sub.36 diacid Cb; (B) from 25 to 70% by weight of glass fibers consisting essentially of silica dioxide (SiO2), aluminum oxide (Al2O3) and magnesium oxide (MgO); said glass fibers (B) consisting of the following composition: from 62 to 66% by weight of SiO2; from 22 to 27% by weight of Al2O3; from 8 to 12% by weight of MgO; from 0 to 9% by weight of calcium oxide (CaO); and from 0 to 1% by weight of other oxides, the total being equal to 100% by weight; (C) from 1 to 20% by weight of at least one impact modifier; and (D) from 0 to 2% by weight of at least one additive, excluding copper chromite, zinc sulfide, titanium dioxide, calcium carbonate and a polyolefin-based colored masterbatch; the sum of the various constituents (A) to (D) being 100% by weight.

2. The composition according to claim 1, wherein the polyamide is selected from PA11, PA12, PA1010, PA1012, PA1210 and PA1212.

3. The composition according to claim 1, wherein the impact modifier is selected from a polyolefin-based polymer having a flexural modulus less than 100 MPa measured according to standard ISO 178:2010 (23° C. RH50) and having a Tg below 0° C. (measured according to standard 11357-2:2013 at the inflection point of the DSC thermogram).

4. The composition according to claim 3, wherein the impact modifier is a polyolefin, said polyolefin being functionalized or non-functionalized, or a mixture of both.

5. The composition according to claim 4, wherein the polyolefin is selected from a functionalized polyolefin or a mixture of functionalized and non-functionalized polyolefins.

6. The composition according to claim 4, wherein the functionalized polyolefin is a polyolefin bearing a function selected from carboxylic acid, maleic anhydride and epoxy functions.

7. The composition according to claim 1, wherein the additives are selected from fluidifying agents, dyes, catalysts, stabilizers, especially thermal stabilizers, UV stabilizers, light stabilizers, surfactants, whitening agents, antioxidants, chain extenders, lubricants, nucleating agents, waxes, and mixtures thereof.

8. The composition according to claim 1, wherein the impact modifier (C) is present at from 1 to 15% by weight.

9. A method for producing the composition as defined in claim 1, wherein the constituents of said composition are mixed by compounding.

10. A molded article obtainable from the composition according to claim 1 by injection molding.

11. The molded article according to claim 10, said article being a quick coupler for the field of transport.

12. The molded article according to claim 10, for the field of electrics and electronics, selected from the group consisting of parts for portable devices.

13. The molded article according to claim 10, for sport shoe soles and for protective items for sport.

Description

EXAMPLES

Compounding

[0193] The compositions were prepared by mixing the polymer granules with the short fibers when melted. This mixture was made by compounding on a twin-screw co-rotating MC26 type extruder with a flat temperature profile)(T° at 230° C. The screw speed is 300 rpm and the flow rate is 25 kg/h.

[0194] The introduction of the glass fibers is achieved by side feeding.

[0195] The additives and the polyamide are added during the compounding process in the main hopper.

[0196] The following compositions were prepared (E=Example of the invention C=Comparative example):

TABLE-US-00001 TABLE 1 E1 C1 C2 C3 C4 C5 C6 C7 PA11 44 — — 49 44 49 — — PA1010 — — — — — — 39 39 PA12 (Vestamid LX 9012) — 91  91  — — — — — Fiber S2 AGY544 50 4 — — — 50 — 60 Fiber E Lanxess E CS7974 — — 4 — — — — — Fibers E 295-10 (Owen Corning) — — — 50 50 — 60 — Exxelor ®VA1840 (Exxon Mobil)  5 —  5 — — — Exxelor ®VA1803 (Exxon Mobil) — 5 5 — — — — — additives  1 — —  1  1  1  1  1

[0197] The mechanical properties of the compositions according to the invention and the comparative compositions were tested:

[0198] The PA11 and PA1010 used were prepared according to methods well-known to those skilled in the art and have a viscosity 400 Pa.Math.s and 100 Pa.Math.s, respectively, as measured with a capillary rheometer of Rheograph 25 type, from the Goettfer brand (die diameter 12 mm) at 260° C., at a shear rate of 110 s-1, according to standard ISO11443:2014.

TABLE-US-00002 TABLE 2 E1 C1 C2 C3 C4 C5 C6 C7 Tensile modulus (GPa) 13.8 1.59 1.48 12 11.6 14 17.4 19.6 Strain at break (MPa) 169 40.4 41.9 155 145 180 185 198 Elongation at break (%) 6.2 267 42.9 5.5 6.7 5 3.2 2.6 Charpy impact strength 33 23.6 26.7 24 32 — 12 12 at 23° C. (kJ/m.sup.2) Charpy impact strength 23 — — 16 17 16 10 11 at −40° C. (kJ/m.sup.2)

[0199] The tensile modulus is measured according to ISO 527 at 23° C.

[0200] The elongation at break and the breaking strength were measured at 23° C. according to standard ISO 527.

[0201] The machine used is of the INSTRON 5966 type. The speed of the crosshead is 1 mm/min for the modulus measurement and 5 mm/min for the strain at break and elongation at break. The test conditions are 23° C., in the dry state. The samples, of ISO 527 1A geometry, were conditioned beforehand for 2 weeks at 23° C., 50% RH. The deformation is measured by a contact extensometer.

[0202] The impact strength was determined according to ISO 179/1eA (Charpy) on notched test specimens of dimension 80 mm×10 mm×4 mm, at temperature of 23° C.+/−2° C. under relative humidity of 50%+/−10% or at −40° C.+/−2° C. under relative humidity of 50%+/−10%.

[0203] These results show that the combination of impact modifier with an amount of at least 10% of glass fibers consisting predominantly of silica dioxide (SiO2), aluminum dioxide (Al2O3) and magnesium oxide (MgO) with a semi-crystalline polyamide is essential for obtaining articles resulting from the compositions of the invention having a tensile modulus and a cold resilience (Charpy impact strength) which are high compared to articles obtained from comparative compositions comprising a combination of impact modifier with an amount of at least 10% type E glass fiber with a semi-crystalline polyamide, or to articles obtained from comparative compositions comprising a combination of impact modifier with an amount of less than 10% of type E or S2 glass fibers with a semi-crystalline polyamide, or else from comparative compositions comprising a combination of an amount of at least 10% of type E or S2 glass fibers with a semi-crystalline polyamide.