Thermoplastic polymer composition having improved mechanical properties

1. A process of making a thermoplastic polymer composition comprising:

A) forming a co-grafted polymeric toughening agent by preparing a mixture, b3), comprising a blend of two or more polyolefins exhibiting at least two glass transition temperatures obtained by feeding in an extruder:

i) 55-90 weight percent of a first polyolefin, b1), with at least one glass transition temperature >−20° C. and a softening temperature >75° C., and is selected from ethylene homo-polymers, propylene homo-polymers and copolymers of ethylene and propylene; and

ii) 10-45 weight percent of a second polyolefin, b2), having highest glass transition temperature <−20° C. and a softening temperature <75° C. and is selected from copolymers of ethylene and alpha olefins and/or dienes, said alpha olefins and/or dienes selected from the group consisting of propylene, 1-butene, 1-hexene; 1-octene, butadiene and norbornene; wherein the weight percents of b1) and b2) are based on 100% of the total weight of i) and ii), and

iii) at least one reactive monomer; and

iv) optionally one peroxide; and

B) melt blending 5 to 40 weight percent of said mixture obtained in step (A) with a polyamide composition comprising:

v) 55 to 90 weight percent semi-crystalline semi-aromatic co-polyamide; wherein said semi-aromatic co-polyamide comprises

a) about 10 to 40 mole percent aromatic repeat units derived from one or more aromatic dicarboxylic acid with 8 to 16 carbon atoms and an aliphatic diamine with 4 to 20 carbon atoms; and

b) about 60 to 90 mole percent aliphatic repeat units derived from one or more aliphatic dicarboxylic acid with 6 to 20 carbon atoms and said aliphatic diamine with 4 to 20 carbon atoms;

vi) 10 to 45 weight percent aliphatic homo-polyamide; wherein said aliphatic homo-polyamide comprises repeat units derived from;

a) an aliphatic dicarboxylic acid with 6 to 20 carbon atoms and an aliphatic diamine with 4 to 20 carbon atoms; or

b) an aliphatic lactam or an aliphatic aminocarboxylic acid with 6 to 20 carbon atoms;

wherein the weight percent of v) and vi) are based on the total weight of v) and vi);

vii) 0 to 15 weight percent of one or more plasticizers;

viii) 0 to 5 weight percent of additives selected from the group consisting of antioxidants, flame retardants, UV stabilizers, light stabilizers, thermal stabilizers, lubricants, and colorants; wherein the weight percent of the mixture b3, components vii), and viii), are based on the total weight of the thermoplastic composition; wherein components v), vi), vii), and viii), are melt blended in step (B) downstream of the first extruder where said mixture, b3) is obtained.

2. The process of claim 1 , wherein the components in step (A) are melt-blended in step (B) in a second extruder.

3. The process of claim 1 , wherein the thermoplastic polymer composition is extruded and pelletized.

4. The process of claim 1 , wherein the mixture of step (A) is extruded and pelletized.

5. The process of claim 1 , further comprising removing unreacted reactive monomer.

6. The process of claim 1 , further comprising extruding and pelletizing the co-grafted polymeric toughening agent.

7. The process of claim 1 wherein said semi-aromatic co-polyamide comprises:

a) about 10 to 40 mole percent aromatic repeat units derived from:

i) one or more aromatic dicarboxylic acids with 8 to 16 carbon atoms and an aliphatic diamine with 4 to 20 carbon atoms; and

b) about 60 to 90 mole percent aliphatic repeat unit derived from:

ii) one or more aliphatic dicarboxylic acids with 6 to 20 carbon atoms and one aliphatic diamine with 4 to 20 carbon atoms; and

wherein said aliphatic homo-polyamide comprises repeat units derived from:

iii) said aliphatic dicarboxylic acid with 6 to 20 carbon atoms and said aliphatic diamine with 4 to 20 carbon atoms.

8. The process of claim 1 wherein the reactive monomer is selected from the group consist of acrylic acid; methacrylic acid; maleic acid; fumaric acid; nadic acid; citaconic acid; itaconic acid; metal salts of the acid, esters, amides or imides of the metal salts or a combinations thereof.

9. The process of claim 1 wherein the co-grafted polymeric toughening agent has a grafting percentage in the range about 0.1 to about 5 weight percent.