Thermoplastic melt-mixed composition with amino acid heat stabilizer
View Patent ↗Disclosed is a thermoplastic melt-mixed composition including: a) a polyamide resin; b) 0.50 to about 5.0 weight percent of one or more amino acid selected from the group consisting of primary amino acids and secondary amino acids; said amino acid having no hydroxyl groups and no more than one carboxylic acid; optionally, c) one or more polyepoxy compound including at least two or more epoxy groups; d) reinforcing agent; e) polymeric toughener; and f) further additives; wherein the weight percents of components a), b), c) d) e) and f) are based on the total weight of the thermoplastic melt-mixed composition. Also disclosed are processes for making the compositions.
1. A thermoplastic melt-mixed composition comprising:
a) 15 to 89.5 weight percent of a polyamide resin selected from Group (III) polyamides having a melting point of at least 230° C., and comprising
(aa) about 20 to about 35 mole percent semiaromatic repeat units derived from monomers selected from one or more of the group consisting of:
(i) aromatic dicarboxylic acids having 8 to 20 carbon atoms and aliphatic diamines having 4 to 20 carbon atoms; and
(bb) about 65 to about 80 mole percent aliphatic repeat units derived from monomers selected from one or more of the group consisting of:
(ii) an aliphatic dicarboxylic acid having 6 to 20 carbon atoms and said aliphatic diamine having 4 to 20 carbon atoms; and
(iii) a lactam and/or aminocarboxylic acid having 4 to 20 carbon atoms;
b) 0.50 to about 4.0 weight percent of one or more amino acids selected from the group consisting of primary amino acids and secondary amino acids; said amino acid having no hydroxyl groups and no more than one carboxylic acid;
c) 0 to 5 weight percent of one or more polyepoxy compound comprising at least two or more epoxy groups; the polyepoxy compound having an epoxide equivalent weight of 43 to 4000 g/equivalent as determined by calculation, or if the polyepoxy compound is an oligomer, by titration using ASTM D1652-11 method; and a number average molecular weight (M n ) of less than 8000;
d) 10 to 60 weight percent reinforcing agent;
e) 0 to 30 weight percent polymeric toughener; and
the weight per cents of components a), b), c) d) and e) are based on the total weight of the thermoplastic melt-mixed composition and wherein 2 mm thick test bars, prepared from said melt-mixed composition and exposed at a test temperature of 230° C. for a test period of 1000 hours, in an atmosphere of air, and tested according to ISO 527-2/1BA, have on average, a retention of tensile strength of at least 40 percent, as compared with that of an unexposed control of identical composition and shape.
2. The thermoplastic melt-mixed composition of claim 1 wherein the amino acid is selected from the group consisting of 6-aminohexanoic acid, lysine, 11-aminoundecanoic acid, 4-aminobenzoic acid; and salts of these amino acids.
3. The thermoplastic melt-mixed composition of claim 1 wherein 0.5 to 5.0 weight percent of the polyepoxy compound comprising at least two or more epoxy groups is present.
4. The thermoplastic melt-mixed composition of claim 1 wherein the polyamide resin is a Group (III) polyamide and is poly(hexamethylene hexanediamide/hexamethylene terephthalamide).
5. The thermoplastic melt-mixed composition of claim 3 wherein the polyepoxy compound has a number average molecular weight of less than 1000.
6. The thermoplastic melt-mixed composition of claim 3 wherein the polyepoxy compound has an epoxide equivalent weight of 70 to 200 g/equivalent.
7. The thermoplastic melt-mixed composition of claim 3 wherein the polyepoxy compound is trimethylolpropane triglycidyl ether.
8. The thermoplastic melt-mixed composition of claim 1 wherein the melt viscosity at a hold time of 25 minutes is less than 600% of the melt viscosity at a hold time of 5 minutes; as measured at temperature 10° C. to 30° C. above the melting point of the polyamide resin, in a capillary rheometer at a shear rate of 1000 sec −1 according to ASTM D3835.
9. A process for providing a thermoplastic melt-mixed composition comprising:
A) melt-blending:
a) 15 to 89 weight percent semi-crystalline polyamide resin having a melting point;
b) 0.50 to about 5.0 weight percent of one or more amino acid selected from the group consisting of primary amino acids and secondary amino acids; said amino acid having no hydroxyl groups and no more than one carboxylic acid;
d) 10 to 60 weight percent of reinforcing agent; and
e) 0 to 30 weight percent polymeric toughener;
to provide a polyamide-poly(amino acid) blend; and
B) melt-blending said polyamide-poly(amino acid) blend with
c) 0.5 to 5.0 weight percent of one or more polyepoxy compound comprising at least two or more epoxy groups;
the polyepoxy compound having an epoxide equivalent weight of 43 to 4000 g/equivalent as determined by calculation, or if the polyepoxy compound is an oligomer, by titration using ASTM D1652-11 method; and a number average molecular weight of less than 8000; wherein said semi-crystalline polyamide resin is selected from the group consisting of Group (III) polyamides having a melting point of at least 230° C., and comprising
(aa) about 20 to about 35 mole percent semiaromatic repeat units derived from monomers selected from one or more of the group consisting of:
(i) aromatic dicarboxylic acids having 8 to 20 carbon atoms and aliphatic diamines having 4 to 20 carbon atoms; and
(bb) about 65 to about 80 mole percent aliphatic repeat units derived from monomers selected form one or more of the group consisting of:
(ii) an aliphatic dicarboxylic acid having 6 to 20 carbon atoms and said aliphatic diamine having 4 to 20 carbon atoms; and
(iii) a lactam and/or aminocarboxylic acid having 4 to 20 carbon atoms;
and wherein the weight percents of components a), b), c), d), and e) are based on the total weight of the thermoplastic melt-mixed composition.
10. The process of claim 9 wherein the thermoplastic melt-mixed composition has a melt viscosity at a hold time of 25 minutes less than 600% of the melt viscosity at a hold time of 5 minutes; as measured at temperature 10° C. to 30° C. above the melting point of the polyamide resin, in a capillary rheometer at a shear rate of 1000 sec −1 according to ASTM D3835.
11. The process of claim 9 wherein one or more of components d) and e) are melt blended with said polyamide-polyacid blend in step B).
12. The process of claim 9 wherein melt-blending said polyamide-poly(amino acid) blend with component b) is provided by metering in said one or more polyepoxy compound by pump into said polyamide-poly(amino acid) blend.
13. The process of claim 9 wherein the amino acid is selected from the group consisting of 6-aminohexanoic acid, lysine, 11-aminoundecanoic acid, 4-aminobenzoic acid; and salts of these amino acids.
14. The process of claim 9 wherein the polyepoxy compound has an epoxide equivalent weight of 70 to 200 g/equivalent.
15. A process for providing a thermoplastic melt-mixed composition comprising:
A) melt-blending:
a) 15 to 99 weight percent semi-crystalline polyamide resin having a melting point;
b) 0.50 to about 5.0 weight percent of one or more amino acid selected from the group consisting of primary amino acids and secondary amino acids; said amino acid having no hydroxyl groups and no more than one carboxylic acid;
c) 0.5 to 5.0 weight percent of one or more polyepoxy compound comprising at least two or more epoxy groups; the polyepoxy compound having an epoxide equivalent weight of 43 to 4000 g/equivalent as determined by calculation, or if the polyepoxy compound is an oligomer, by titration using ASTM D1652-11 method; and a number average molecular weight of less than 8000;
d) 0 to 60 weight percent of reinforcing agent; and
e) 0 to 30 weight percent polymeric toughener;
to provide a polyamide-poly(amino acid) blend;
wherein said semi-crystalline polyamide resin is selected from the group consisting of Group (III) polyamides having a melting point of at least 230° C., and comprising
(aa) about 20 to about 35 mole percent semiaromatic repeat units derived from monomers selected from one or more of the group consisting of:
(i) aromatic dicarboxylic acids having 8 to 20 carbon atoms and aliphatic diamines having 4 to 20 carbon atoms; and
(bb) about 65 to about 80 mole percent aliphatic repeat units derived from monomers selected form one or more of the group consisting of:
(ii) an aliphatic dicarboxylic acid having 6 to 20 carbon atoms and said aliphatic diamine having 4 to 20 carbon atoms; and
(iii) a lactam and/or aminocarboxylic acid having 4 to 20 carbon atoms;
and wherein components b) amino acid and c) polyepoxy compound are added simultaneously during the melt-blending.
16. The process of claim 15 wherein the thermoplastic melt-mixed composition has a melt viscosity at a hold time of 25 minutes less than 600% of the melt viscosity at a hold time of 5 minutes; as measured at temperature 10° C. to 30° C. above the melting point of the polyamide resin, in a capillary reohmeter at a shear rate of 1000 sec −1 according to ASTM D3835.
17. The process of claim 15 wherein the amino acid is selected from the group consisting of 6-aminohexanoic acid, lysine, 11-aminoundecanoic acid, 4-aminobenzoic acid; and salts of these amino acids.
18. The process of claim 15 wherein the polyepoxy compound has an epoxide equivalent weight of 70 to 200 g/equivalent.