| 摘要 |
<p>#CMT# #/CMT# Preparing polyamides, comprises polymerization of one or more different types of monomers and/or oligomers in the presence of additives comprising one or more carboxylic acids, diamides and alkyl-substituted phenols and/or thiols, where the total content of diamide and phenol and/or thiol is 0.9-3 wt.%. #CMT# : #/CMT# An independent claim is included for a polyamide prepared by the above method. #CMT#USE : #/CMT# The polyamide is useful for the production of polyamide fibers, moldings or coatings (claimed). #CMT#ADVANTAGE : #/CMT# The use of a multi-component additive system regulates the degree of polycondensation and the molecular distribution width and protects the polymer or its derived products such as textile fibers and molding materials from heat, light, moisture and oxygen. The additive system has a positive influence on the viscoelastic properties of the polymer melt due to reduced melt elasticity. The process involves the addition of the stabilizing additives before or during the polymerization reaction for avoiding the need of additional stabilizers to be mixed with the polymers or its derived products, thus by forming the stabilizer molecules at the ends of the polymer chains, the loss of stabilizer by evaporation, extraction or migration is prevented and thus ensures its sustained effectiveness both in manufacturing and in the processing and use of polyamides. The additive system provides stabilized polyamides with bulky or sterically hindered chain for producing highly-oriented fabric which can be drawn at speeds of more than 5500 m/minutes. #CMT#ORGANIC CHEMISTRY : #/CMT# Preferred Components: The amounts of carboxylic acid, diamide and phenol and/or thiol are 0.01-3 wt.%, 0.01-3 wt.% and 0.001-2 wt.%, respectively and the molar ratio of carboxylic acids and diamides is 8:1-2:1. The sum of diamide and phenol and/or thiol is 1-2.5 wt.%, preferably 1.2-2 wt.%. The diamide is of formula (R1-NH-CO-R2-CONH-R1) (I), preferably bis-(2,2,6,6-tetramethylpiperidin-4-yl)-isophthalic acid diamide or bis-(2,2,6,6-tetramethylpiperidin-4-yl) terephthalic acid diamide. The carboxylic acid is a dicarboxylic acid, preferably terephthalic acid. The phenol is 2,6-di-tert-butyl-p-cresol. The thiol is 2-isopropylthiophenol or mercaptobenzimidazole. R1 : alkyl, benzyl (optionally substituted), naphthyl, pyridyl, and/or piperidyl; R2 : primary, secondary or tertiary alkyl group of formula C nH 2 nor aromatic ring; and n : 2-12. Preferred Process: The additives are added simultaneous or in a timely manner during or before the polymerization process. #CMT#POLYMERS : #/CMT# Preferred Components: The polyamide is preferably poly(caprolactam), a copolymer comprising a monomer, preferably caprolactam and at least one comonomer, preferably an aromatic comonomer, which is aminobenzoic acid. #CMT#EXAMPLE : #/CMT# A stirred autoclave was charged with caprolactam (2500 g) and 4-amino benzoic acid (12.5 g), demineralized water (2 wt.%) and the additive system comprising terephthalic acid (24 mmol/kg), N,N-bis-(tetramethylpiperidin-4-yl)-isophthalic acid diamide (3 mmol/kg) and mercaptobenzimidazole (2 mmol/kg). The mixture was heated to 260[deg] C under an autogenous pressure of 4 bar for an hour, followed by a relaxation period of 30 minutes, in which the pressure in the reactor was gradually reduced to atmospheric level. The polymerization to poly(caprolactam) happened isothermally at 260[deg] C, and within 3 hours before a vacuum phase above 120 mbar at 950 minutes the polymer process was completed. The effluent of the polymer melt finished the batch process, where the overpressure of nitrogen discharged it into a water bath and the cooled polymer extrudate was then dried and granulated.</p> |
