Semiaromatic polyamides, processes for preparing the same and compositions containing the same

A process for preparing a semiaromatic polyamide, comprising the steps of:

• bringing terephthalic acid and optionally isophthalic acid and an aliphatic dicarboxylic acid of 4 to 18 carbon atoms into contact with an aliphatic diamine of 4 to 12 carbon atoms, to prepare a semiaromatic polyamide comprising 40 to 90% by mol of (A) recurring units derived from the terephthalic acid and the aliphatic diamine of 4 to 12 carbon atoms, 0 to 50% by mol of (B) recurring units derived from the isophthalic acid and the aliphatic diamine of 4 to 12 carbon atoms, 0 to 60% by mol of (C) recurring units derived from the aliphatic dicarboxylic acid of4 to 18 carbon atoms and the aliphatic diamine of 4 to 12 carbon atoms and 0 % by mol of (D) recurring units derived from the lactam of 6 to 20 carbon atoms or the aminocarboxylic acid, and
• bringing the semiaromatic polyamide into contact with an aqueous medium to decrease the content of boiling water-soluble components (MO components) in the semiaromatic polyamide to not more than 0.25% by weight.

A process for preparing a semiaromatic polyamide, comprising the steps of:

• bringing terephthalic acid and optionally isophthalic acid and an aliphatic dicarboxylic acid of 4 to 18 carbon atoms into contact with an aliphatic diamine of 4 to 12 carbon atoms, to prepare a semiaromatic polyamide comprising 40 to 90% by mol of (A) recurring units derived from the terephthalic acid and the aliphatic diamine of 4 to 12 carbon atoms, 0 to 50% by mol of (B) recurring units derived from the isophthalic acid and the aliphatic diamine of 4 to 12 carbon atoms, 0 to 60% by mol of (C) recurring units derived from the aliphatic dicarboxylic acid of 4 to 18 carbon atoms and the aliphatic diamine of 4 to 12 carbon atoms and 0% by mol of (D) recurring units derived from the lactam or the aminocarboxylic acid of 6 to 20 carbon atoms, and
• melt extruding the semiaromatic polyamide with supplying an inert gas into the polyamide resin to decrease the content of boiling water-soluble components (MO components) in the semiaromatic polyamide.

A process for preparing a semiaromatic polyamide, comprising the steps of:

• bringing terephthalic acid and optionally isophthalic acid and an aliphatic dicarboxylic acid of 4 to 18 carbon atoms into contact with an aliphatic diamine of 4 to 12 carbon atoms, to prepare a semiaromatic polyamide prepolymer comprising 40 to 90% by mol of (A) recurring units derived from the terephthalic acid and the aliphatic diamine of 4 to 12 carbon atoms, 0 to 50% by mol of (B) recurring units derived from the isophthalic acid and the aliphatic diamine of 4 to 12 carbon atoms, 0 to 60% by mol of (C) recurring units derived from the aliphatic dicarboxylic acid of 4 to 18 carbon atoms and the aliphatic diamine of 4 to 12 carbon atoms and 0% by mol of (D) recurring units derived from the lactam or the aminocarboxylic acid of 6 to 20 carbon atoms,
• subjecting the semiaromatic polyamide prepolymer to solid phase polymerization, and
• post polymerizing the semiaromatic polyamide prepolymer by an extruder to decrease the content of boiling water-soluble components (MO components) in the semiaromatic polyamide.