POLYPROPYLENE COMPOSITE

Abstract

Polyvinyl alcohol fiber reinforced polypropylene composition with excellent impact/stiffness balance as well as to its preparation and use.

Claims

1-12. (canceled)

13. A fiber reinforced polypropylene composition comprising (a) 98.0 to 50.0 wt % of a matrix (M) comprising a polypropylene (PP), (b) 2.0 to 50.0 wt % of polyvinyl alcohol (PVA) fibers and (c) 0.0 to 5.0 wt % of a polar modified polypropylene as coupling agent (CA), based on the total weight of the fiber reinforced composition, wherein the sum of (a), (b) and (c) is 100.0 wt %; wherein the composition (i) has a tensile strain at break measured at 23 C. according to ISO 527-2 (cross head speed 50 mm/min) of at least 8% and (ii) a Charpy notched impact strength at 23 C. ISO 179-1eA:2000 of at least 10.0 kJ/m.sup.2.

14. The fiber reinforced polypropylene composition according to claim 13, wherein the polypropylene (PP) of the matrix (M) is a propylene homopolymer (H-PP1) having (i) a melt flow rate MFR2 (230 C.) measured according to ISO 1133 of from 1 to 500 g/10 min, (ii) a melting temperature Tm in the range of 150 to 175 C., (iii) a isotactic pentad concentration of higher than 90 mol %, and (iv) a xylene cold soluble content (XCS) of not more than 5 wt %.

15. The fiber reinforced polypropylene composition according to claim 13, wherein the polypropylene (PP) of the matrix (M) is a heterophasic propylene copolymer (HECO) having a) a xylene cold soluble content (XCS) measured according ISO 6427 (23 C.) in the range of 8.0 to 35 wt %, and/or b) a melt flow rate MFR.sub.2 (230 C.) measured according to ISO 1133 of from 1 to 300 g/10 min, and/or c) a total ethylene and/or C.sub.4 to C.sub.8 -olefin content of 5.0 to 25 wt %, based on the total weight of the heterophasic propylene copolymer (HECO).

16. The fiber reinforced polypropylene composition according to claim 15, wherein the heterophasic propylene copolymer (HECO) comprises a) a polypropylene matrix (M-HECO), being a propylene homopolymer (H-PP2), and b) an elastomeric copolymer (E).

17. The fiber reinforced polypropylene composition according to claim 13, wherein the polyvinyl alcohol (PVA) fibers have (i) a tenacity of at least 0.4 N/tex up to 1.7 N/tex, (ii) a fiber length of 2.0 to 20 mm, and (ii) a fiber average diameter in the range of 10 to 20 m.

18. The fiber reinforced polypropylene composition according to claim 13, wherein the polar modified polypropylene as coupling agent (CA) is a modified polypropylene having a polar group or groups, wherein the polar group or groups are derived from polar compounds selected from the group consisting of acid anhydrides, carboxylic acids, carboxylic acid derivatives, primary and secondary amines, hydroxyl compounds, oxazoline, and epoxides.

19. The fiber reinforced polypropylene composition according to claim 18, wherein the polar compounds are selected from maleic anhydride and compounds selected from C.sub.1 to C.sub.10 linear and branched dialkyl maleates, C.sub.1 to C.sub.10 linear and branched dialkyl fumarates, itaconic anhydride, C.sub.1 to C.sub.10 linear and branched itaconic acid dialkyl esters, maleic acid, fumaric acid, itaconic acid, and mixtures thereof.

20. The fiber reinforced polypropylene composition according to according to claim 13, which has (i) a tensile strain at break measured at 23 C. according to ISO 527-2 (cross head speed 50 mm/min) of at least 10% and (ii) a Charpy notched impact strength at 23 C. ISO 179-1eA:2000 of at least 12.0 kJ/m.sup.2.

21. The fiber reinforced polypropylene composition according to claim 13, which has a tensile strength measured at 23 C. according to ISO 527-2 (cross head speed 50 mm/min) of at least 35 MPa.

22. An article comprising the polypropylene composition according to claim 13.

23. The article according to claim 22, which is selected from car interior and exterior parts, comprising at least to 60 wt % of the polypropylene composition.

24. A process for preparing the fiber reinforced composition according to claim 13, comprising the steps of adding (a) polypropylene (PP), (b) the polyvinyl alcohol (PVA) fibers, and (c) optionally the polar modified polypropylene as coupling agent (CA) to an extruder and extruding the same and obtaining said fiber reinforced composition.

Description

EXPERIMENTAL PART

A) Methods

Tensile Tests:

[0125] The tensile strength and the tensile strain at break were measured at 23 C. according to ISO 527-2 (cross head speed 50 mm/min) using injection moulded specimens moulded at 230 C. according to ISO 527-2(1A), produced according to EN ISO 1873-2 (dog bone shape, 4 mm thickness).

Charpy Impact Test:

[0126] The Charpy notched impact strength (NIS) was measured according to ISO 179-1eA:2000 at +23 C., using injection-molded bar test specimens of 80104 mm.sup.3 prepared in accordance with ISO 1873-2:2007.

B) Materials Used

For Matrix (M):

PP-Homopolymer (PP-H):

[0127] HJ325MO: a polypropylene homopolymer containing nucleating and antistatic additives, provided by Borealis. (CAS-No: 9003-07-0)

[0128] This polymer is a CR (controlled rheology) grade with narrow molecular weight distribution, density of 905 kg/m.sup.3 (ISO1183) and an MFR.sub.2 of 50 g/10 min (230 C.; 2.16 kg; ISO 1133); XS of 2.2 wt % and melting temperature of 164 C. and a Charpy Notched Impact Strength at 23 C. of 2.0 kJ/m.sup.2

Heterophasic Copolymer (PP-HECO):

[0129] BG055AI: nucleated high crystallinity PP impact copolymer having an MFR (230 C./2.16 kg) of 22 g/10 min, an elastomer content of 18 wt % as determined by the content of xylene solubles (XS) and a density of 920 kg/m.sup.3. The polymer contains 2 wt % of talc, based on the total weight of the polymer.

[0130] Tensile Strength [MPa] is 35 MPa, Charpy Notched Impact Strength at 23 C. is 3.5 kJ/m.sup.2; Tensile Strain at Break is 32%.

PVA Fibers:

[0131] Chopped PVA-fibres Mewlon 2000T-750F HM1 (High Modulus), fibre-length 4 mm, tenacitity of 1 N/tex, Young Modulus of 21.5 N/tex with a specific surface-treatment for PP, supplied by Unitika

Coupling Agent (CA):

[0132] commercial maleic anhydride functionalized polypropylene Scona TPPP 8112FA of Kometra GmbH, Germany with a density of 0.9 g/cm.sup.3, having an MFR.sub.2 (190 C.; 2.16 kg) of 100 g/10 min and an MAH content of 1.4 mol %.

Comparative Example 1 (CE1)

[0133] GB205U is a commercially glass fibre reinforced composite of Borealis AG containing 20 wt % chemically coupled glass fibers embedded in a propylene homopolymer matrix, having an MFR.sub.2 (230 C.) of 2.2 g/10 min and a melting temperature of 166 C.

Examples

[0134] PP-compositions were produced using a parallel, co-rotating twin-screw extruder Brabender DSE20 (screw-diameter 20 mm, length 40d) with four vertical ports at 0, 10, 20 and 30d which can be used for dosing and venting. All four downstream-zones were electrically heated and water-cooled. The extruder has two side-feeders at 11 and 22d. Polymer and additives were fed through vp1, vp2 and vp4 were used for atmospheric venting (vp3 remained closed). The fibres were fed through sp1 via the side-feeder.

[0135] The standard compounding-melt-temperature was 190 C.

[0136] A water-bath, cooled to about 15 C., and a strand pelletizer Primo 50 by Rieter were used to granulate the melt extruded through a die with a diameter of 3.0 mm. All components were fed via Motan-Colortronic gravimetric dosing scales. Single screw scales were employed for the polymer and the MA-PP. The fibres were fed via a GBS-C twin screw system.

[0137] From Table 1 the composition of the Inventive Examples 1 to 5 (IE1 to IE5) can be seen:

TABLE-US-00001 TABLE 1 IE1 IE2 IE3 IE4 IE5 Matrix (M) [wt %] PP-H 78.0 90.0 80.0 70.0 PP-HECO 78.0 Fibers [wt %] PVA-fiber 20.0 20.0 10.0 20.0 30.0 Tencel-fiber Coupling Agent (CA) [wt %] Scona TPPP 2.0 2.0 0.0 0.0 0.0

[0138] From Table 2 the properties of the Inventive Examples 1 to 5 (IE1 to IE5) and of Comparative Example 1 can be seen:

TABLE-US-00002 TABLE 2 IE1 IE2 IE3 IE4 IE5 CE1 Tensile Strength [MPa] 68 57 45 56 59 89 Tensile Strain at Break % 13.3 12.4 14.2 13.2 12.7 3.4 Charpy Notched (23 C.) kJ/m.sup.2 29.8 16.9 12.7 30.4 48.9 10.5

[0139] From this table and from FIGS. 1 to 5 it can be clearly seen that the compositions of the invention, i.e. the PVA-fiber reinforced PP compositions have an improved strain@break and tensile strength balance in combination with excellent impact performance, even if no coupling agent is used.

[0140] The advantages of the compositions of the invention, i.e. the PVA-fiber reinforced PP compositions over comparable compositions (using glass fibers) can be furthermore seen in the determined notched impact performance which is superior to conventional homo PP based GF composites.