Polyamide moulding composition and use thereof

Abstract

A thermoplastic moulding composition, in particular a polyamide moulding composition, consisting of, by weight: (A) 20-88%—thermoplastic material; (B) 10-60%—fibrous fillers, formed from (B1) 10-60%—glass fibers, selected from: glass fibres (B1_1) with a non-circular cross section, wherein the axis ratio of the main cross-sectional axis to the secondary cross-sectional axis is at least 2; high-strength glass fibres (B1_2) with a glass composition (substantially SiO2, AlO, and MgO; or mixtures thereof; (B2) 0-20%—glass fibres, different from glass fibres of component (B1) and have a circular cross section; and (B3) 0-20%—further fibrous tillers, different from fibres of (B1) and (B2), not based on glass, and selected from the group: carbon fibres, graphite fibres, aramid fibres, nanotubes; (C) 2-10%—LDS additive or a mixture of LDS additives; (D) 0-30%—particulate filler; (E) 0-2%—further, different additives; the sum of (A)-(E) is 100% by weight.

Claims

1. A thermoplastic moulding composition consisting of: (A) 20-63% by weight of a thermoplastic material consisting of polyamide (A1) or a mixture of polyamides, wherein said polyamide (A1) or mixture of polyamides is selected to be at least one semicrystalline aliphatic polyamide (A1_1) or a mixture of at least one semicrystalline aliphatic polyamide (A1_1) with at least one amorphous polyamide (A1_3), wherein the at least one semicrystalline aliphatic polyamide (A1_1) is selected from the group consisting of at least one of PA12 and PA1010 and wherein the at least one amorphous polyamide (A1_3) is selected to be PA6I/6T with a proportion ratio 6T:6I in the range of 20:80 to 45:55; (B) 35-60% by weight of high-strength glass fibres (B1_2) based on the ternary system silicon dioxide/aluminium oxide/magnesium oxide or on the quaternary system silicon dioxide/aluminium oxide/magnesium oxide/calcium oxide, and having the following composition: 58-70% by weight of silicon dioxide (SiO.sub.2), 15-30% by weight of aluminium oxide (Al.sub.2O.sub.3), 5-15% by weight of magnesium oxide (MgO), 0-10% by weight of calcium oxide (CaO) and 0-2% by weight of further different oxides; (C) 3-6% by weight of laser direct structuring additive or a mixture of laser direct structuring additives, wherein the component (C) is copper(I) oxide, copper(II) oxide, or mixtures of such systems; (D) 0% by weight of particulate filler; (E) 0-2% by weight of further, different additives; wherein the sum of (A)-(E) makes up 100% by weight.

2. The moulding composition according to claim 1, wherein the proportion of component (A) lies in the range of 25-63% by weight.

3. The moulding composition according to claim 1, wherein the high-strength glass fibre (B1_2) has a circular cross section.

4. The moulding composition according to claim 1, wherein the component (C) is an laser direct structuring additive with an absorption coefficient, different from zero, for ultraviolet, visible or infrared radiation, which forms metal nuclei under the action of electromagnetic radiation, and facilitates and/or enables and/or improves the chemical metallising deposition of conductor tracks at the irradiated points.

5. The moulding composition according to claim 4, wherein the component (C) is an laser direct structuring additive with an average particle size (D50) in the range of 50-10,000 nanometres, and/or has an aspect ratio of at most 10.

6. The moulding composition according to claim 1, wherein the glass fibres of component (B) are present in the form of short fibres, or in the form of endless fibres.

7. A component based on a moulding composition according to claim 1.

8. The moulding composition as claimed in claim 1, wherein the high-strength glass fibres of component (B1_2) have the following composition: 60-67% by weight of silicon dioxide (SiO.sub.2), 20-28% by weight of aluminium oxide (Al.sub.2O.sub.3), 7-12% by weight of magnesium oxide (MgO), 0-9% by weight of calcium oxide (CaO) and 0-1.5% by weight of further oxides.

9. The moulding composition according to claim 1, wherein the glass fibres of component (B) are present in the form of short fibres, in the form of cut glass with a length in the range of 0.2-20 mm.

10. A component having electrical conductor tracks, based on a moulding composition according to claim 1.

11. A component having electrical conductor tracks, based on a moulding composition according to claim 1, as a casing or casing part for portable electronic devices, as PDAs, mobile telephones, telecommunications devices, casings or casing parts for personal computers, notebooks, medical devices, i hearing aids, sensor technology, or RFID transponders or parts for the automotive field, as air bag modules and multi-function steering wheels.

12. The molding composition according to claim 1, wherein the component (C) is a chelate compound of, copper(I) oxide, copper (II) oxide or mixtures of such systems.

Description

DESCRIPTION OF PREFERRED EMBODIMENTS

(1) The invention will be described hereinafter with use of specific exemplary embodiments (B) and compared with the less efficient systems according to the prior art (VB). The exemplary embodiments specified below are intended to support the invention and to demonstrate the differences from the prior art, but are not intended to limit the general subject matter of the invention, as is defined in the claims.

EXAMPLES B1 TO B6 AND COMPARATIVE EXAMPLES VB1 TO VB6

(2) The components specified in Tables 1 to 4 were compounded in a twin-screw extruder by Werner and Pfleiderer having a screw diameter of 25 mm under predefined process parameters (see Table 1), wherein the polyamide granulate and the additives were metered into the feed zone, whereas the glass fibre was metered into the polymer melt via a side feeder, 3 housing units before the die. The composition summarised in Tables 2, 3 and 4 were removed in the form of a strand from a die having a 3 mm diameter and were granulated after water cooling. The granulate was dried for 24 hours at 110° C. under vacuum of 30 mbar. With regard to the moulding composition of examples B6 and VB6, the granulation was carried out by means of underwater granulation or die-face pelletisation under water, in which the polymer melt is pressed through a hole-type die and is granulated directly after the exit from the die by a rotating blade in a water flow. After granulation and drying at 120° C. for 24 h, the granulate properties were measured and the test specimen was produced.

(3) TABLE-US-00001 TABLE 1 Compounding and injection moulding conditions for the examples and comparative examples B1, B2, B3, B4, VB1, VB3, B5, B6, Compounding/processing parameter VB2 VB4 VB5 VB6 compounding cylinder temperatures 260 270 250 330 screw rotational speed 200 200 150 150 throughput 10 10 8 8 injection cylinder temperatures 260 260 240 330 moulding mould temperature 40 40 80 120 screw perimeter speed 15 15 15 15
Processing:

(4) The compositions were injection moulded using an Arburg Allrounder 320-210-750 injection moulding machine at defined cylinder temperatures in zones 1 to 4 and at a defined mould temperature (see Table 1) to form test specimens.

(5) TABLE-US-00002 TABLE 2 Composition and properties of examples B1 and B2 and also of comparative examples VB1, VB2-1 to VB2-3 Unit B1 B2 VB1 VB2-1 VB2-2 VB2-3 Composition PA1010 % by 36.6 36.6 36.6 36.6 36.6 36.6 weight PA 6I/6T (70:30) % by 9.1 9.1 9.1 9.1 9.1 9.1 weight glass fibre E10 % by 50.0 54.0 weight glass fibre S10 % by 50.0 54.0 weight glass fibre E7x28 % by 50 54 weight copper chromite (Cu.sub.2CrO.sub.4) % by 4.0 4.0 4.0 0 0 0 weight Irganox 1098 % by 0.3 0.3 0.3 0.3 0.3 0.3 weight Properties tensile modulus of elasticity MPa 15300 12900 11500 17300 15500 14300 tear strength MPa 167 139 135 205 207 203 elongation at tear % 2.5 2.0 2.1 3.4 2.9 3.5 impact toughness 23° C. kJ/m.sup.2 59 50 44 74 93 78 notch toughness 23° C. kJ/m.sup.2 11 9 8 14 20 14 metallisation index — 0.65 0.70 0.68 n.d n.d n.d adhesive strength [N/mm] 1.35 1.48 1.16 n.d n.d n.d adhesive strength after storage — 0. 0 1 n.d n.d n.d

(6) TABLE-US-00003 TABLE 3 Composition and properties of examples B3 and B4 and also of comparative examples VB3, VB4-1 to VB4-3 Unit B3 B4 VB3 VB4-1 VB4-2 VB4-3 Composition PA 12 % by 45.7 45.7 45.7 49.7 49.7 49.7 weight glass fibre E10 % by 50.0 50.0 weight glass fibre S10 % by 50.0 50.0 weight glass fibre E7x28 % by 50 50 weight copper chromite (Cu.sub.2CrO.sub.4) % by 4.0 4.0 4.0 0 0 0 weight Irganox 1098 % by 0.3 0.3 0.3 0.3 0.3 0.3 weight Properties tensile modulus of elasticity MPa 12900 12400 11100 13500 13200 12000 tear strength MPa 152 119 115 165 180 160 elongation at tear % 3.3 2.6 2.8 5.5 3.3 5.3 impact toughness 23° C. kJ/m.sup.2 65 55 48 78 98 73 notch toughness 23° C. kJ/m.sup.2 18 16 12 24 29 23 metallisation index- — 0.46 0.52 0.49 n.d n.d n.d adhesive strength [N/mm] 0.94 1.01 1.06 n.d n.d n.d adhesive strength after storage — 0 0 0 n.d n.d n.d

(7) TABLE-US-00004 TABLE 4 Composition and properties of examples B5 and B6 and also of comparative examples VB5 and VB6 Unit B5 VB5 B6 VB6 Composition PA1010 % by 44.6 44.6 weight PA 6I/6T (70:30) % by 11.1 11.1 weight PA6T/6I/10T/10I % by 67.7 67.7 weight glass fibre E10 % by 30.0 30 weight glass fibre S10 % by weight glass fibre E7x28 % by 30.0 30 weight copper chromite (Cu.sub.2CrO.sub.4) % by 4.0 4.0 3.0 3.0 weight Irganox 1098 % by 0.3 0.3 0.3 0.3 weight Microtalc IT extra % by 10.0 10.0 weight Properties tensile modulus of elasticity MPa 11200 10100 11300 10900 tear strength MPa 120 110 155 143 elongation at tear % 2.1 2.1 2.2 1.8 impact toughness 23° C. kJ/m.sup.2 48 32 59 35 notch toughness 23° C. kJ/m.sup.2 10 7 16 9 metallisation index- — 0.85 0.78. 0.72 0.65 adhesive strength [N/mm] 1.55 1.40 0.94 0.88 adhesive strength after storage — 0 0 0 1 n.m.: non-metallisable; n.d.: not determined Key: PA 6I/6T (70:30) amorphous, semi-aromatic polyamide based on terephthalic acid, isophthalic acid and 1,6-hexanediamine, with a glass transition temperature of 125° C. and a solution viscosity of 1.54. PA 1010 semi-crystalline, aliphatic polyamide based on 1,10-decandiamine and sebacic acid, with a melting point of 200° C. and a solution viscosity of 1.78. PA 12 semi-crystalline, aliphatic polyamide based on laurolactam, with a melting point of 178° C. and a solution viscosity of 1.96. PA MACM12 amorphous polyamide based on bis-(4-amino-3-methyl-cyclohexyl)-methane and dodecane diacid, with a glass transition temperature of 156° C. and a solution viscosity of 1.82. PA 6T/6I/10T/10I semi-crystalline, semi-aromatic polyamide, produced from 29.66% by weight of hexanediamine, 15.35% by weight of decanediamine, 47.25% by weight of terephthalic acid and 7.48% by weight of isophthalic acid with a melting point of 318° C. and a solution viscosity of 1.62. glass fibre E10 cut glass fibres Vetrotex 995 consisting of E-glass, with a length of 4.5 mm and a diameter of 10 μm (circular cross section) by Owens Corning Fibreglass glass fibre F7x28 cut glass fibres CSG3PA-820 consisting of E-glass, with a length of 3 mm, a main cross-sectional axis of 28 μm, a secondary cross-sectional axis of 7 μm and an axis ratio of 4 (non-circular cross section) by NITTO BOSEKI, Japan glass fibre S10 cut glass fibres Vetrotex 995 consisting of E-glass, with a length of 4.5 mm and a diameter of 10 μm (circular cross section) by Owens Coming Fibreglass copper chromite Shepherd Black 30C965 (The Shepherd Color Company), copper chromite (CuCr2O4) with a mean particle size of 0.6 μm.

(8) Contrary to expectations, comparative tests VB2-1 to VB2-3 demonstrate that there are no advantages in terms of tear strength and elongation at tear for the reinforcement by means of S-glass fibres or flat E-glass fibres compared to round E-glass fibres. The values for tear strength, elongation at tear and impact toughness achieved for the moulding compositions argue against the selection of the S-glass fibres, The round E-glass fibre is practically equivalent apart from the tensile modulus of elasticity, and the flat E-glass fibres are considerably superior with respect to tear strength and impact toughness.

(9) If an LDS additive, such as copper chromite (black spinet), is then added to these moulding compositions in a concentration of 4%, the mechanical properties of all moulding compositions considered thus worsen, sometimes drastically. However, mechanical properties of the moulding compositions (B1 and B2) reinforced with the S-glass fibre and with flat E-glass fibres decrease less severely than the moulding composition based on conventional E-glass (VB1).

(10) The moulding compositions based on polyamide PA12 and summarised in Table 2 behave similarly. In this case too, the filler-free moulding composition reinforced with S-glass (VB4-1) also demonstrates hardly any advantages in respect of the mechanical properties compared to the cost-effective E-glass fibre (VB4-3), and even demonstrate disadvantages compared to the flat E-glass fibre (VB4-2). The flat E-glass fibre demonstrates advantages with regard to impact toughness. Only with the addition of copper chromite are the advantages of the S-glass fibre and the flat E-glass fibre evident, specifically considerably improved tear strength and greater elongation at tear and impact toughness.

(11) Even with a predominantly amorphous matrix, as in examples B5 and VB5, approximately the same conditions as described above are produced. For the moulding composition according to the invention, there is a much greater tear strength and improved impact toughness with considerably greater rigidity.

(12) The measurements were taken in accordance with the following standard and on the following test specimens. Tensile modulus of elasticity: ISO 527 with a strain rate of 1 mm/min ISO tension bar, standard: ISO/CD 3167, A1 type, 170×20/10×4 mm, temperature 23° C. Tear strength, elongation at tear: ISO 527 with a strain rate of 5 mm/min ISO tension bar, standard: ISO/CD 3167, A1 type, 170×20/10×4 mm, temperature 23° C. Impact toughness, notch toughness by Charpy: ISO 179 ISO test bar, standard: ISO/CD 3167, B1 type, 80×10×4 mm at temperature 23° C. Melting point (Tm), enthalpy of fusion (ΔHm) and glass transition temperature (Tg): ISO standard 11357-11-2 granulate Differential scanning calorimetry (DSC) was carried out with a heating rate of 20° C./min. The temperature for the onset is specified for the glass transition temperature (Tg). Relative Viscosity: DIN EN ISO 307, in 0.5% by weight of m-cresol solution, temperature 20° C. granulate
Laser Structuring:

(13) In order to assess the metallisation behaviour, injection-moulded parts (plate 60×60×2 mm) were structured with the aid of an Nd:YAG laser and were then metallised currentlessly in a copper-plating bath. During the laser structuring process, 18 adjacent areas measuring 5×7 mm in size were irradiated over the surface of the moulded part. The laser structuring process was carried out by means of an LPKF Microline 3D laser at a wavelength of 1064 mm and an irradiation breadth of approximately 50 μm at a rate of 4 m/s. Here, both the pulse frequency and the power of the laser were varied. For the specific pulse frequencies of 60, 80 and 100 kHz, the power was varied in each case in the range of 3-17 watt. The moulded parts were then subjected, after the laser structuring process, to a cleaning process in order to remove the residues of the laser process. Here, the moulded parts pass through successive ultrasonic baths with surfactant and deionised water. The cleaned moulded parts are then metallised in a reductive copper-plating bath (MacDermid MID-Copper 100 B1) for 60-80 minutes. In so doing, copper is deposited on the areas irradiated by the laser in an average thickness of 3 to 5 μm.

(14) Metallisation Index:

(15) The degree of metallisation was determined in comparison to a reference material (PBT Pocan 7102). Here, the quotient (=metallisation index) from the copper layer thickness on the material in question and that on the reference material is established. The layer thickness of the conductor track is determined by means of X-ray fluorescence spectroscopy.

(16) Adhesive Strength:

(17) The adhesion of the copper conductive tracts produced is measured in a peel test in accordance with DIN IEC 326-3-7.1.

(18) Adhesive Strength after Storage:

(19) The adhesion of the copper layer after various storage conditions is obtained by means of the cross-cut test in accordance with EN DIN ISO 2409. For this purpose, 6 cuts continuing to the substrate are made at right angles using a multiple cutting blade with a cut spacing of 1 mm, such that a lattice pattern is produced. An adhesive strip having defined adhesive force is then pressed onto the cross-cut so that loose copper layer areas or copper layer areas adhering poorly to the substrate are removed. The visual assessment is carried out with the aid of an illuminated magnifier. The degree of adhesion is classified in accordance with the characteristic values 0-5, defined as follows: 0: the edges of the cuts are completely smooth; none of the squares of the lattice is chipped. 1: small splinters of the coating are chipped at the points of intersection of the lattice lines; chipped area is no greater than 5% of the cross-cut area. 2. the coating is chipped along the edges of the cut and/or at the points of intersection of the lattice lines. Chipped area is greater than 5%, but no greater than 15% of the cross-cut area. 3: the coating is chipped along the edges of the cuts in wide strips, either partially or completely, and/or some squares are chipped partially or completely. Chipped area is greater than 30%, but no greater than 50% of the cross-cut area, 4: the coating is chipped along the edges of the cuts in wide strips, and/or some squares are chipped completely or partially. Chipped area is greater than 35%, but no greater than 65% of the cross-cut area. 5: any chipping that can no longer be classified as grid cut characteristic value 4.
Storage Conditions:

(20) The adhesion of the conductor track was measured with the aid of the above-described grid cut test after two different storage phases under the following conditions: Profile 1: dry, temperature change from −40° C. to 85° C., 6 cycles, each lasting 8 h. Profile 2; 95% relative humidity, temperature change from 25° C. to 55° C., 6 cycles, each lasting 24 h.

(21) With all MID techniques, the chemically-reductive copper deposition is the decisive start metallisation process, which is key to the quality of the overall layer. It is therefore quite sufficient to assess the quality of the primary metal layer. In order to produce the finished MID part, nickel and then an end layer consisting of immersion gold are generally then deposited on the first copper layer (primary layer). Of course, other metal layers, such as further copper, palladium, tin or silver layers, can also be applied to the primary layer.