Thermoplastic composition based on polyamide, polyketone and novolac resin

Abstract

A thermoplastic composition based on polyamide and polyketone is described. The thermoplastic composition can have an excellent mechanical strength and dimensional stability. Further, the composition can include a novolac resin and a reinforcing or a bulking filler. The composition can be molded, for example in the form of granules or powder, which is used for manufacturing articles via an injection-molding process.

Claims

1. A melt-blended composition comprising 40% to 98% by weight of a polyamide; 1% to 20% by weight of a polyketone; and 1% to 20% by weight of a novolac resin, with respect to the total weight of the composition.

2. The composition as described by claim 1, wherein the polyamide is selected from the group consisting of: a PA 66, a PA 610, a PA 612, a PA 6.66, a PA 46, a MXD6, a PA 66/6T, a PA 6, a PA 11 and a PA 12.

3. The composition as described by claim 1, wherein the polyketone is aliphatic.

4. The composition as described by claim 1, wherein the polyketone is represented by the formula:
(COCH.sub.2CH.sub.2).sub.x(CO-A).sub.y- in which A denotes an unsaturated monomer having at least 3 carbon atoms and the x/y ratio is at least 2.

5. The composition as described by claim 1, wherein the polyketone is a copolymer of ethylene and carbon oxide.

6. The composition as described by claim 1, wherein the composition comprises a reinforcing or bulking filler and/or an impact modifier.

7. A method of reinforcing mechanical properties of a polyamide, the method comprising melt-blending a novolac resin and a polyketone with the polyamide to form the melt-blended composition according to claim 1.

8. The composition as described by claim 1, wherein the polyketone is a copolymer of ethylene, propylene and carbon oxide.

9. The composition as described by claim 1 comprising 40% to 96% by weight of the polyamide.

10. A molded article comprising a melt-blended composition comprising: 40% to 98% by weight of a polyamide; 1% to 20% by weight of a polyketone; and 1% to 20% by weight of a novolac resin, with respect to the total weight of the composition.

11. The molded article as described by claim 10, wherein the molded article is an injection molded article.

12. The composition according to claim 1, comprising 88% to 96% by weight of a polyamide; 2% to 6% by weight of a polyketone; and 2% to 6% by weight of a novolac resin, with respect to the total weight of the composition.

Description

EXPERIMENTAL PART

Example 1

Manufacture of the Compositions

(1) Compositions based on polyamide 6 PA- (reference S27BL from Rhodia Engineering Plastics, H.sub.2SO.sub.4 relative viscosity of 147 ml/g) and different proportions of aliphatic polyketone PK (Carilon D26HM100 Shell Chemicals) and novolac resin NO (Phenol-Formaldehyde Rhenosin PR95) are obtained by extrusion on a miniextruder.

(2) The characteristics of the processing are as follows:

(3) Twin-screw miniextruder: PRISM 25D, 16 mm screw, L/D=25, with: a temperature profile: of 225 C. for PA6 and 270 C. for PA66 screw speed (rpm): 300 motor force (N.m): 20 venting: air

(4) The rods coming out of the extruder are run into a water cooling tank and subsequently granulated. Test specimens are produced by injection molding in the following way:

(5) Arburg Allrounder 350-90 220 D press, 30 mm screw, L/D=15

(6) Max. clamping force: 350 kN

(7) T ( C.) barrel: from 250 to 275

(8) T ( C.) mold: 80

(9) Injection rate (mm/s): 87.7

(10) Injection pressure (bar): 42

(11) Hold pressure (bar): 28

(12) Backpressure (bar): 4

(13) Screw speed (rpm): 195

Example 2

Analysis of the Formulations

(14) Various tests were carried out on the formulations produced in example 1. The results are expressed in the following table 1:

(15) TABLE-US-00001 TABLE 1 Water uptake at equi- Break- Tough- librium Young's Yield ing ness Systems (weight Modulus stress stress @50RH PA PK NO Ex. %) (MPa) (MPa) (%) (kJ/m.sup.2) 100 0 0 C1 3.6 3017 73.1 58.6 67 98 2 0 C2 3.5 3058 72.9 72.4 195 96 4 0 C3 3.5 2974 70.4 71.7 197 94 6 0 C4 3.5 3011 70.0 70.7 197 92 8 0 C5 3.4 2931 68.5 68.7 189 98 0 2 C6 3.3 2933 74.2 62.7 53 96 0 4 C7 3.3 2869 75.2 61.0 32 94 0 6 C8 3.1 2778 78.1 62.5 25 92 0 8 C9 2.9 2690 79.5 63.8 14 96 2 2 1 3.4 3372 78.5 68.4 182 92 4 4 2 3.0 4005 83.9 78.7 n.m. 88 6 6 3 2.8 3865 83.5 77.2 n.m. n.m. = not measured

(16) The proportions of PA, PK and NO are expressed as percentage by weight with respect to the total weight of the composition. The water absorption measurements are carried out according to the standard ISO 1110. The Young's modulus is measured according to the standard ISO527. The yield stress is measured according to the standard ISO527. The breaking stress is measured according to the standard ISO527. The impact strength measurements are carried out according to the standard ISO 179-1/1eA.