Foamable polyamide composition and foam obtained therefrom

Abstract

Provided is a foamable polyamide composition comprising a) at least one polyamide comprising at least one carboxylic group; b) at least one thermoplastic rubber; and c) at least one compound having at least one isocyanate group; and optionally d) at least one filler and e) at least one additive.

Claims

1. A foamable composition consisting essentially of: a) 21.0 to 99.6 wt % of a polyamide 6,6 comprising at least one carboxylic group; b) 1.0 to 4.5 wt % of a styrene-ethylene/butylene-styrene thermoplastic elastomer; c) 0.1 to 3.0 wt % of hexamethylene diisocyanate biuret; d) 0 to 65.0 wt % of at least one filler selected from the group consisting of glass fibers, glass beads, calcium carbonate, silicates, talc, kaolin, mica, carbon black, graphite, wood powders, and synthetic fibers; and e) 0 to 2.0 wt % of at least one additive; wherein the sum of wt % of the components a) to e) is 100 wt % of the composition.

2. The foamable composition according to claim 1, wherein the at least one additive is selected from the group consisting of an antioxidant, a pore-forming agent, a surfactant, a nucleating agent, a plasticizer, a matting agent, a pigment, a colorant, a heat stabilizer, a light stabilizer, a bioactive agent, an antisoiling agent, an antistatic agent, flame retardant, and a catalyst to accelerate decarboxylation by reaction of the carboxylic acid functional groups with isocyanate functional groups.

3. The foamable composition according to claim 1, wherein the composition includes about 5 to 65.0 wt % of the at least one filler.

4. The foamable composition according to claim 1, wherein the at least one filler is selected from the group consisting of glass fibers, glass beads, calcium carbonate, silicates, talc, kaolin, mica, carbon black, graphite, and wood powders.

5. The foamable composition according to claim 1, wherein the at least one filler is glass fibers.

6. The foamable composition according to claim 1, wherein the composition consists essentially of: a) 40.0 to 98.7 wt % of the polyamide 6,6 comprising at least one carboxylic group; b) 1.0 to 4.5 wt % of the styrene-ethylene/butylene-styrene thermoplastic elastomer; c) 0.3 to 1.5 wt % of the hexamethylene diisocyanate biuret; d) 15 to 45.0 wt % of the at least one filler selected from the group consisting of glass fibers, glass beads, calcium carbonate, silicates, talc, kaolin, mica, carbon black, graphite, wood powders, and synthetic fibers; and e) 0.1 to 2.0 wt % of the at least one additive.

7. A method for producing the foamable composition according to claim 1, comprising: i) preparing a master-batch comprising a mixture of the styrene-ethylene/butylene-styrene thermoplastic elastomer and the hexamethylene diisocyanate biuret; ii) heating the polyamide 6,6; and optionally the at least one filler at a temperature equal to or greater than a melting point of the polyamide to obtain a molten polyamide matrix; and iii) adding at least a portion of the master-batch to the molten polyamide matrix.

8. A foam obtained from the foamable composition according to claim 1.

9. An aeronautical vehicle, a motor vehicle, packaging, or sound insulation comprising the foam according to claim 8.

10. A motor vehicle comprising the foam according to claim 8.

Description

EXAMPLES

(1) The compositions used are as follows:

(2) Examples 1 and 2 (for Comparative Examples): mixtures of polyamide 6,6, HDB (hexamethylene diisocyanate biuret), glass fiber and antioxidant.

(3) Examples 3 and 4: mixtures of polyamide 6,6, HDB, SEBS (styrene-ethylene/butylene-styrene), glass fiber and antioxidant.

(4) Chemical reagents used in the Examples are specified as follows: HDB: Tolonate HDB® from VencoreX SEBS: Taipol® 6150 from Third Sector Research Centre (TSRC) Glass fiber: 289H from Nippon Electric Glass (NEG) Polyamide: Technyl® 27B10 from Solvay Antioxidant: Irganox® B1171 from BASF

(5) The compositions prepared are detailed in Table 1 below. The proportions are indicated in weight percentages in the composition.

(6) TABLE-US-00001 TABLE 1 Ex. 1 Comp. Ex. 2 Comp. Ex. 3 Ex. 4 Polyamide 69.1 68.8 67.7 66.7 HDB 0.6 0.9 0.6 0.9 SEBS 0 0 1.4 2.1 Glass fiber 30 30 30 30 Antioxidant 0.3 0.3 0.3 0.3 Total 100 100 100 100

Comparative Examples 1 and 2 (Hereinafter, Ex, 1 and 2 Comp.)

(7) Heating polyamide 6,6 was carried out at a temperature of greater than or equal to its melting point to produce a molten polyamide 6,6. Ex. 1 and 2 Comp. were obtained by mixing said molten polyamide 6,6, HDB, glass fiber, and antioxidant together in a TES-30 twin-screw co-extrusion type extruder from JSW (Japan Steel Works) Corporation, with a screw length/diameter ratio of 40, while glass fibers being introduced through side feeder. The extrusion temperatures were 250-250-250-250-260-260-230-210-150° C. from nozzle to hopper, and the throughput and RPM were 30 kg/hr and 300, respectively.

(8) The extrudates were then cooled in water at room temperature. The foaming ratio was determined as 2.8% and 4.2%, respectively, with respect to the total volume of Ex. 1 and 2 Comp.

(9) Further, the flexural strength and the flexural modulus were measured using a Universal Test Machine (UTM) according to ASTM D790. In addition, the notch Izod was measured according to ASTM D256.

Examples 3 and 4 (Hereinafter, Ex. 3 and 4)

(10) The master-batches for Ex. 3 and 4 were first prepared by mixing SEBS and HDB together. A molten polyamide 6,6 matrix was likewise produced by heating polyamide 6,6, glass fibers and antioxidant together at a temperature of greater than or equal to the melting point of polyamide 6,6. Said master-batches were subsequently introduced into the molten polyamide 6,6 matrix through a side feeder to obtain Ex. 3 and 4, respectively.

(11) Ex. 3 and 4 were placed in the same extruder. The extrusion conditions were the same with those for Ex. 1 and 2 Comp.

(12) The extrudates were likewise cooled in water at room temperature. The foaming ratio was determined as 11.6% and 14.8%, respectively, with respect to the total volume of Ex. 3 and 4.

(13) Flexural strength, flexural modulus, and notch Izod were also measured. The measurement was performed using the same conditions and the same instrument, as detailed above.

(14) The foaming ratio and the above mechanical parameters of the foam obtained from the Examples 1 to 4, which correspond to Ex. 1 and 2 Comp. and Ex. 3 and 4, respectively, are summarized in Table 2 below.

(15) TABLE-US-00002 TABLE 2 Ex. 1 Comp Ex. 2 Comp Ex. 3 Ex. 4 Foaming Ratio (%) 2.8 4.2 11.6 14.8 Flexural strength (MPa) 244 238 231 221 Flexural modulus (MPa) 8,200 8,000 7,500 7,100 notch Izod (J/m) 135 130 125 110

(16) As being confirmed from the experimental data in Table 2, the foaming ratios of Ex. 3 and 4 were noticeably increased compared to those of Ex. 1 and 2 Comp. Also, mechanical properties of the Examples 3 and 4, including flexural strength, flexural modulus and notch Izod, were still in a satisfactory level to be used as a light-weight material in a motor vehicle application such as engine cover, rocker box, etc.