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Process for reducing caprolactam and its oligomers in nylon-6 pre-polymer

一种己内酰胺、预聚物的技术，应用在制备聚酰胺领域，能够解决没有公开低分子杂质等问题

Inactive Publication Date: 2007-11-14
INVISTA TECHNOLOG IES S A R L
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Among them, the reference patent does not disclose how to obtain low-molecular-weight impurities in the nylon prepolymer prepared by small pressure drop followed by water extraction

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0015] Example 1: Pressure Drop and Caprolactam Prepolymer Curing

[0016] 27.8 g of a 6.2 RV (Relative Viscosity) Nylon-6 prepolymer containing 6.8 wt% caprolactam and 0.7 wt% cyclic dimer were added to the reactor along with 2.2 g water and 0.3 g nitrogen. The resulting mixture was heated to 240°C, mixed and forced through a 0.0762 cm diameter orifice with a pressure upstream of the orifice of 4137 kPa (600 psi). The obtained nylon-6 powder had an RV of 4.4, a caprolactam content of 9.8 wt%, and a cyclic dimer content of 0.8 wt%. The resulting powder was brought into contact with cold water (20° C.) for 15 seconds in a beaker. The contents of the beaker were filtered to separate the powder from the water, which resulted in an additional contact time of about 30 seconds for the powder and water. Through this process, the caprolactam content of the powder was reduced to 1.8 wt%, and the cyclic dimer content was reduced to 0.2 wt%. The pressure drop is 4137 kPa (600 psig). ...

Embodiment 2

[0017] Example 2: Pressure Drop, Repressurization, Subsequent Contact with Water and Curing of Caprolactam Prepolymer

[0018] A 75 wt% aqueous solution of caprolactam was heated to 272°C in an autoclave, and a pressure of 1724 kPa (250 psig) was maintained for 2 hr. Then, while keeping the temperature constant, the pressure was reduced to atmospheric pressure over 15 min and then repressurized with nitrogen to 345 kPa (50 psig) and held for 30 min. Finally, the product was rapidly discharged as a continuous strand through two 0.635 cm diameter holes, which was collected in a vat of cold water. After contacting with water for 5 minutes, the product was taken out, and analyzed, it was found that the RV was 18, and the contents of caprolactam and cyclic dimer were 3.6 wt% and 0.4 wt%, respectively.

Embodiment 3

[0019] Example 3: Application of pressure drop to aminocapronitrile prepolymer followed by contact with water

[0020] 251b of 6-aminocapronitrile and 101b of water were added to the autoclave and heated to 260°C. Water sparging at 100 cc / min was started in this step and heating was continued to 275°C. The pressure relief is set at 4137 kPa (600 psig), and the water sparge is maintained for 3 hr. The pressure was then reduced to 345 kPa (50 psig) over 90 minutes while the temperature dropped to 260°C. After the pressure drop, the product exits through 2 holes of 0.635 cm diameter and jets into a vat of cold water. After 2 min of contact, the product was removed and analyzed. The polymer RV was 7.9, and its caprolactam and cyclic dimer contents were 2.0 wt% and 0.61 wt%, respectively.

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PUM

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Abstract

Disclosed is a process for reducing low molecular weight impurities, namely caprolactam and its oligomers, from Nylon-6 pre-polymer during the preparation of Nylon-6 polymer.

Description

technical field [0001] The present invention relates to a process for the preparation of polyamides. More particularly, the present invention relates to a method for removing low molecular weight impurities, particularly caprolactam and caprolactam cyclic dimers, from nylon-6 prepolymers during the preparation of nylon-6 polymers. Background technique [0002] Polyamides are traditionally prepared by polycondensation of diacids, such as adipic acid, and diamines, such as hexamethylenediamine, or, alternatively, by polymerization of lactams, such as ε-caprolactam. Other processes are known involving the preparation of polyamides by the reaction of ω-aminonitriles with water. US Patent 2,245,129 discloses the preparation of polyamides by heating ω-aminonitriles in the presence of water. US Patent 6,069,228 describes a process for producing polyamide polymers by forming prepolymers. [0003] Polyamide prepolymers produced from ε-caprolactam or ω-aminocapronitrile contain lar...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C08G69/04C08G69/16C08G69/38C08F6/00C08G69/08C08G69/18C08J3/00
CPCC08G69/18C08G69/16C08G69/04C08G69/08C08G69/14C08G69/26
Inventor A·W·阿尔索普C·E·坎普J·M·伊瓦西克D·拉亚戈帕兰
Owner INVISTA TECHNOLOG IES S A R L
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