Method for reducing residual lactam monomer from polyamide compounds
View Patent ↗Residual lactam monomer is reduced from compounds containing polyamide by adding a minor amount of polycarbodiimide during melt-mixing.
1. A method for reducing residual lactam content in a compound containing polyamide, comprising the steps of:
(a) selecting the polyamide containing residual lactam;
(b) melt-mixing the polyamide with an effective amount of polycarbodiimide to reduce the residual lactam without reducing Notched Izod properties of the polyamide, measured by ASTM D-256 by more than 6.4%;
wherein the polycarbodiimide has a melting point greater 130° C. and an average molecular weight of more than 20,000 g/mole.
2. The method of claim 1 , wherein the polyamide comprises polycaprolactam homopolymers, polycaprolactam copolymers, poly(12-aminododecanoic acid) homopolymers, or poly(12-aminododecanoic acid) copolymers.
3. The method of claim 1 , wherein the polyamide is blended with a resin selected from the group consisting of polyolefins, polyimides, polycarbonates, polyesters, polysulfones, polylactones, polyacetals, acrylonitrile-butadiene-styrene resins, polyphenylene ether, polyphenylene sulfide, polystyrene, styrene-acrylonitrile resins, styrene maleic anhydride resins, aromatic polyketones, Surlyn™ ionomer, and mixtures thereof.
4. The method of claim 1 , wherein the compound contains ingredients in the following weight percent ranges:
Polyamide Resin
26-99.8
Other Thermoplastic Resin
0-50
Polycarbodiimide
0.2-4
Optional Additives
0-20.
5. The method of claim 1 , wherein the compound contains ingredients in the following weight percent ranges:
Polyamide Resin
32-99.5
Other Thermoplastic Resin
0-50
Polycarbodiimide
0.5-3
Optional Additives
0-15.
6. The method of claim 1 , wherein the compound contains ingredients in the following weight percent ranges:
Polyamide Resin
37.5-99
Other Thermoplastic Resin
0-50
Polycarbodiimide
1-2.5
Optional Additives
0-10.
7. A compound prepared according the method of claim 1 .
8. A plastic article shaped from the compound of claim 7 .
9. The article of claim 8 , wherein the article is shaped by extruding, molding, calendering, or thermoforming.
10. The article of claim 8 , wherein the article is a transportation-related molded item, electrical equipment, or a consumer appliance housing or container.