Process for production of polyamide
AssigneeMitsubishi Gas Chemical Company, Inc.
InventorsHideyuki Kurose, Kazumi Tanaka
Life of this patent
Estimating the term…
Abstract
In the production of polyamide by the melt-polymerization of the present invention, the polymerization conditions are rapidly and accurately controlled by a near-infrared spectroscopy to enable the efficient production of a desired polyamide with a good stability in its quality.
Claims32
A process for producing a polyamide constituted of a dicarboxylic acid unit comprising 80% by mol or more of an aliphatic dicarboxylic acid unit having 6 to 12 carbon atoms and a diamine unit comprising 80% by mol or more of xylylenediamine unit or bisaminomethylcyclohexane unit, the process comprising:
- (1) performing a melt-polymerization in batch-wise manner by adding a diamine monomer directly into a molten dicarboxylic acid monomer, thereby producing a polyamide;
- (2) measuring, in the absence of bubbles, (A) a molar ratio of a diamine component and a dicarboxylic acid component in a reaction mixture, and (B) at least one property selected from the group consisting of a water content of the reaction mixture, and a carboxyl end group concentration, an amino end group concentration, a molecular weight, a relative viscosity and a melt viscosity of the polyamide obtained in the step (1) using a near-infrared spectrometer when a number average molecular weight of the polyamide obtained in the step (1) reaches 6000 to 20,000, the diamine component including the diamine monomer remaining in the reaction mixture not polymerized and the diamine monomer polymerized to constitute the polyamide obtained in the step (1), and the dicarboxylic acid component including the dicarboxylic acid monomer remaining in the reaction mixture not polymerized and the dicarboxylic acid monomer polymerized to constitute the polyamide obtained in the step (1);
- and
- (3) regulating the molar ratio to a desired level and determining a time for further continuing the melt-polymerization and the timing for changing the polymerization conditions on the basis of measured values (A) and (B), while continuing the melt-polymerization.
A process for producing a polyamide constituted of a dicarboxylic acid unit comprising 80% by mol or more of an aliphatic dicarboxylic acid unit having 6 to 12 carbon atoms and a diamine unit comprising 80% by mol or more of xylylenediamine unit or bisaminomethylcyclohexane unit, the process comprising:
- (1) performing a melt-polymerization in batch-wise manner by adding a diamine monomer directly into a molten dicarboxylic acid monomer, thereby producing a polyamide;
- (2) measuring, in the absence of bubbles, (A) a molar ratio of a diamine component and a dicarboxylic acid component in a reaction mixture, and (B) at least one property selected from the group consisting of a water content of the reaction mixture, and a carboxyl end group concentration, an amino end group concentration, a molecular weight, a relative viscosity and a melt viscosity of the polyamide obtained in the step (1) using a near-infrared spectrometer when a number average molecular weight of the polyamide obtained in the step (1) reaches 6000 to 20,000, the diamine component including the diamine monomer remaining in the reaction mixture not polymerized and the diamine monomer polymerized to constitute the polyamide obtained in the step (1), and the dicarboxylic acid component including the dicarboxylic acid monomer remaining in the reaction mixture not polymerized and the dicarboxylic acid monomer polymerized to constitute the polyamide obtained in the step (1);
- (3) regulating the molar ratio to a desired level or determining a time for further continuing the melt-polymerization and the timing for changing the polymerization conditions on the basis of measured values (A) and (B), while continuing the melt-polymerization;
- (4) repeating the measurements (A) and (B) just before discharging a polyamide obtained in the step (3) from a melt-polymerization apparatus;
- and
- (5) controlling polymerization conditions of a subsequent melt-polymerization on the basis of measured values (A) and (B) obtained in the step (4).
A process for producing a polyamide constituted of a dicarboxylic acid unit comprising 80% by mol or more of an aliphatic dicarboxylic acid unit having 6 to 12 carbon atoms and a diamine unit comprising 80% by mol or more of xylylenediamine unit or bisaminomethylcyclohexane unit, the process comprising:
- (1) performing a melt-polymerization in batch-wise manner by adding a diamine monomer directly into a molten dicarboxylic acid monomer, thereby producing a polyamide;
- (2) measuring, in the absence of bubbles, (A) a molar ratio of a diamine component and a dicarboxylic acid component in a reaction mixture, and (B) at least one property selected from the group consisting of a water content of the reaction mixture, and a carboxyl end group concentration, an amino end group concentration, a molecular weight, a relative viscosity and a melt viscosity of the polyamide obtained in the step (1) using a near-infrared spectrometer when a number average molecular weight of the polyamide obtained in the step (1) reaches 6000 to 20,000, the diamine component including the diamine monomer remaining in the reaction not polymerized and the diamine monomer polymerized to constitute the polyamide obtained in the step (1), and the dicarboxylic acid component including the dicarboxylic acid monomer remaining in the reaction mixture not polymerized and the dicarboxylic acid monomer polymerized to constitute the polyamide obtained in the step (1);
- (3) regulating the molar ratio to a desired level or determining a time for further continuing the melt-polymerization and the timing for changing the polymerization conditions on the basis of measured values (A) and (B), while continuing the melt-polymerization;
- (4) repeating the measurements (A) and (B) just before discharging a polyamide obtained in the step (3) from a melt-polymerization apparatus, and solidifying the polyamide obtained in the step (3) by cooling;
- and
- (5) controlling polymerization conditions of a subsequent solid-phase polymerization on the basis of measured values (A) and (B) obtained in the step (4).
Dependencies are inferred from the claim text.