Thermoplastic composition and article

Abstract

The invention is directed to a thermoplastic composition and to an article made from said thermoplastic composition. More in particular, the invention relates to blended polyolefinic materials, which, after molding, provide a soft touch feel. The thermoplastic composition of the invention comprises (A) 10-40% by total weight of the composition of glass fibers; (B) 22-46% by total weight of the composition of a propylene homopolymer matrix phase; (C) 1.5-26% by total weight of the composition of an ethylene-propylene copolymer dispersed phase; and (D) 11-46% by total weight of the composition of a mixture of elastomers, said mixture comprising an ethylene/C.sub.5-8 -olefin copolymer and an ethylene/C.sub.3-4 -olefin copolymer.

Claims

1. A thermoplastic composition comprising, (A) 10-40% by total weight of the composition of glass fibres; (B) 22-46% by total weight of the composition of a propylene homopolymer matrix phase; (C) 1.5-26% by total weight of the composition of an ethylene-propylene copolymer dispersed phase; and (D) 11-46% by total weight of the composition of a mixture of elastomers, said mixture comprising an ethylene/C.sub.5-8 -olefin copolymer and an ethylene/C.sub.3-4 -olefin copolymer.

2. A thermoplastic composition according to claim 1, wherein said ethylene-C.sub.5-8 -olefin copolymer is an ethylene/C.sub.6-8 olefin copolymer.

3. A thermoplastic composition according to claim 1, wherein said ethylene/C.sub.3-4 -olefin is copolymer of ethylene and 1-butene.

4. A thermoplastic composition according to claim 1, wherein the ethylene/C.sub.5-8 -olefin copolymer and the ethylene/C.sub.3-4 -olefin copolymer are present in a weight ratio of 5:1 to 1:1.

5. A thermoplastic composition according to claim 1, wherein said propylene homopolymer phase (B) and said ethylene propylene copolymer dispersed phase (C) are a homopolymer-based matrix phase and a dispersed elastomeric phase of a heterophasic polypropylene copolymer.

6. A thermoplastic composition according to claim 1, wherein the elastomers in the mixture (D) are different from the ethylene-propylene copolymer dispersed phase (C).

7. A thermoplastic composition according to claim 1, further comprising (E) a heterophasic polypropylene copolymer having a melt flow index of 50 g/10 min or more as measured at 190 C. under 2.16 kg force according to ISO 1133.

8. A thermoplastic composition according to claim 1, wherein the elastomers in the mixture have a density of 850-880 kg/m.sup.3 and a melt flow index of 0.5-35 g/10 min as measured at 190 C. under 2.16 kg force according to ISO 1133.

9. A thermoplastic composition according to claim 1, wherein the glass fibres have a filament diameter of 10-20 m.

10. A thermoplastic composition according to claim 1, further comprising (F) a modified polypropylene, wherein said modified polypropylene is a polypropylene grafted with one or more selected from the group consisting of a carboxylic acid or salts thereof, an anhydride, and an ester.

11. A thermoplastic composition according to claim 1, further comprising (G) a silicone particle having the formula (I)
R.sub.xSiO.sub.2(x/2)(I) wherein x is a positive number greater than or equal to 1, and each R is independently an aliphatic hydrocarbon group, or an aromatic hydrocarbon group.

12. A thermoplastic composition according to claim 1, further comprising (H) a polysiloxane, wherein said polysiloxane comprises an ultra high molecular weight polysiloxane with a kinematic viscosity of 1010.sup.6 cSt or more as determined in accordance with ASTM D445 at 25 C.

13. A thermoplastic composition according to claim 1, further comprising 0.1-2% by total weight of the composition of one or more selected from the group consisting of a thermal stabiliser, a UV stabiliser, a visible light stabiliser, and an antioxidant.

14. An article made from a thermoplastic composition according to claim 1.

15. An article according to claim 14, in the form of one or more selected from automotive exterior parts, bumper fascia, door panels automotive interior parts, instrument panels, consoles, interior trim parts, door grips, shift boot, dashboard, and parts for electrical appliances.

16. A thermoplastic composition according to claim 1, wherein said ethylene-C.sub.5-8 -olefin copolymer is an ethylene/C.sub.7-8 -olefin copolymer, and wherein the ethylene/C.sub.5-8 -olefin copolymer and the ethylene/C.sub.3-4 -olefin copolymer are present in a weight ratio of 3:1 to 1:1.

17. A thermoplastic composition according to claim 16, wherein said ethylene-C.sub.5-8 -olefin copolymer is a copolymer of ethylene and 1-octene; and wherein the ethylene/C.sub.5-8 -olefin copolymer and the ethylene/C.sub.3-4 -olefin copolymer are present in a weight ratio of 2:1 to 1:1.

Description

EXAMPLES

(1) Melt Flow Index

(2) The melt flow index was measured according to ISO 1133 with a load of 2.16 kg at 230 C.

(3) Ash Content

(4) The ash content was determined according to ISO 3451 as measured after 15 minutes at 525 C.

(5) Notched Izod Impact Strength

(6) Notched Izod impact strength was determined according to ISO 180/1A (II) on notched samples of 80104 mm at 23 C. and 20 C.

(7) Tensile Modulus

(8) Tensile modulus was measured according to ISO 527/1A at 1 mm/min and 23 C. Test specimens as described in EN ISO 1873-2 (80104 mm) were used.

(9) Soft-touch Performance

(10) Soft-touch performance was determined by a panel of 9 experts in soft touch properties. Specifically, the experts felt the surface of the respective compositions and assigned it a haptic rating to +++, where a haptic rating of +++ was the best and was the worst.

(11) Tiger-stripe performance

(12) Samples of the compositions were injection moulded into two types of ruler-shaped test specimens. Two types of moulds were used, a so-called fan gate mould and a so-called pin-point gate mould. The molten polyolefin composition was extruded through a nozzle having an upper end having a diameter of 4 mm and a lower end having a diameter of 7 mm. The lower end of the nozzle merges with a rectangular channel of the mould.

(13) Along the length of the fan gate mould, the width changes from about 6.5 mm to 30 mm and the thickness changes from about 3 mm to 2 mm. After the fan shaped part, an elongated part follows having a width of 30 mm and a thickness of 3 mm. The rectangular part is about 34 mm in length. The fan shaped part of the mould is about 225 mm in length.

(14) The pin-point gate mould is identical to the fan gate except that the rectangular part comprises a portion having a width of 1.2 mm over a length of about 6 mm.

(15) The melt temperature during the injection moulding is set at 200 C., 230 C., or 260 C., respectively, and the mould is kept at room temperature. Three different screw speeds are used according to the following conditions.

(16) TABLE-US-00001 Screw speed Flow rate Injection Condition injection [mm/s] [cm.sup.3/s] time [s] Low speed 20 14.1 2.49-2.51 Medium speed 50 35.3 0.99-1.0 High speed 160 113.1 0.38-0.39
Specimens having a smooth side and a textured side were manufactured. After moulding each of the specimens is visually observed for occurrence of tiger stripes on its smooth side and on its textured side. The quality of the surface was evaluated on a scale of 1 to 10, 10 being the best performance.

(17) TABLE-US-00002 1 very sharp transition between glossy and dull sections visible seen from any angle 2 sharp transitions between glossy and dull sections seen from any angle 3 very visible transitions between glossy and dull sections seen from any angle 4 visible transitions between glossy and dull sections seen from any angle 5 less visible transitions between glossy and dull sections seen from any angle 6 visible transitions between glossy and dull sections seen from a specific angle only 7 less visible transitions between glossy and dull sections seen from a specific angle only 8 no transitions between glossy and dull sections visible and surface appearance inhomogeneous 9 no transitions between glossy and dull sections visible and surface appearance homogeneous 10 no transitions between glossy and dull sections visible and surface is perfect
The average tiger stripe rating is defined as the numerical average of the individual tiger stripe ratings for each of the test specimens manufactured at low, medium and high speed, manufactured with the pin-gate and the fan-gate and measured on the smooth and on the textured surface. Hence, the average tiger stripe rating as defined herein is the average of 12 individual tiger stripe measurements.

(18) Compositions as defined in table 1 were prepared by blending the different components together in the indicated amounts. With the resulting compositions parts were prepared by injection moulding, which were subsequently analysed for various properties, as shown in table 2.

(19) It is clear from table 2 that the compositions of the invention result in an improvement of the soft-touch performance and of the tiger stripe performance. Moreover, the mechanical properties of the parts obtained by the composition of the invention are excellent.

(20) TABLE-US-00003 TABLE 1 Comparative Inventive Inventive example example 1 example 2 Heterophasic polypropylene 5 8 copolymer having a melt flow index of more than 50 g/10 min [wt. %] Heterophasic polymer with 18.5 10 10 10 wt. % of ethylene-propylene copolymer dispersed in a propylene homopolymer [wt. %] Heterophasic polymer with 24 31.4 26.4 23.4 wt. % of ethylene-propylene copolymer dispersion in a propylene homopolymer [wt. %] Copolymer of ethylene and 8 12 1-butene [wt. %] Copolymer of ethylene and 25 17 13 1-octene [wt. %] Glass fibres [wt. %] 25 25 25 Talc filler [wt. %] 0.5 0.5 0.5 Silicone particles [wt. %] 1 1 1 Polysiloxane [wt. %] 1 1 1 Fatty acid amide [wt. %] 0.1 0.1 0.1 Additives [wt. %] 6 6 6 Total 100 100 100

(21) TABLE-US-00004 TABLE 2 Comparative Inventive Inventive example example 1 example 2 Melt flow index [dg/min] 9.1 8.3 8.2 Ash content [%] 27.6 27.6 27 Izod ISO 180/1A (II) at 23 C. 35 33 34 [kJ/m.sup.2] Izod ISO 180/1A (II) at 20 C. 15.7 15.3 16.8 [kJ/m.sup.2] Tensile ISO 527/1A at 23 C. 2810 3193 3069 [N/mm.sup.2] Soft-touch performance + ++ +++ Tiger-stripe performance at 200 C., inj. speed; 7 7 7 textured, - at 200 C., inj. speed; 7 8 7 textured, at 230 C., inj. speed; 6 7 7 textured, - at 230 C., inj. speed; 6 6 7 textured, at 260 C., inj. speed; 7 7 8 textured, - at 260 C., inj. speed; textured, 7 7 8 -: fan gate : pin point