Process for producing stibium-free environment-friendly polyethylene terephthalate for bottle

Abstract

The invention relates to a preparation method of polyethylene therephthalate used in an antimony-free environmentally-friendly bottle. The technical process of the technology is that: fine terephthalic acid and ethylene glycol are stirred in a slurry mixing can, are pumped into a slurry feeding can, and then enter an esterification kettle through a slurry injection nozzle to generate oligomer. Additives on siphonium line of the esterified oligomer are injected into a prepolymerization kettle through a pump and materials, after reaching the top of the prepolymerization kettle, and flow to a final polymerization kettle. The method is characterized in that the additives on a pipeline from the oligomer and into the prepolymerization kettle comprise a catalyst, a stabilizer and a dispersant, wherein, the catalyst is titanium-cobalt composite catalyst, the stabilizer is polyphosphoric acid and the dispersant is cage-type silsesquioxane; a pipe reactor is arranged on the pipeline from the oligomer and into the prepolymerization kettle, the additives are dissolved respectively in ethylene glycol to prepare a mixture liquid, the mixture liquid, after being fed into the can, is injected into the pipeline from the oligomer and into the prepolymerization kettle by using the nozzle, and enters the prepolymerization kettle after being mixed evenly in the pipe reactor. The preparation method is excellent in decentrality and low in b value.

Description

(1) Technical field [0001] The invention relates to a preparation method of non-antimony environment-friendly polyethylene terephthalate for bottles. Mainly used in food container packaging, beverage packaging and other fields. (2) Background technology [0002] Polyethylene terephthalate (PET) for bottles is not only one of the most important synthetic fiber raw materials, but also very important in the fields of food container packaging and beverage packaging. Catalyst is an important part of polyester production, and there are many metal catalysts that can synthesize polyester. In the current large-scale polyester production, antimony-based catalysts are mostly used as catalysts. Because antimony compounds themselves have certain toxicity and coexist with highly toxic arsenic in nature, the application of antimony-based catalysts is limited to a certain extent. In terms of environmental protection, in the polycondensation reaction of polyester, the antimony-based cataly...

AI Technical Summary

Problems solved by technology

In the current large-scale polyester production, antimony-based catalysts are mostly used as catalysts. Since antimony compounds themselves have certain toxicity and coexist with highly toxic arsenic in nature, the application of antimony-based catalysts is limited to a certain extent.

In terms of environmental protection, in the polycondensation reaction of polyester, the antimony-based catalyst will be partially reduced to gray. When the synthetic polyester is spun, the accumulation of heavy metals will increase the pressure on the spinning assembly, and the residual antimony will entrain PET when it melts. Sublimation together, the contained antimony will be precipitated in the PET dyeing process and cause environmental pollution

Therefore, in recent years, many companies have been researching antimony-free bottle-grade polyester chips. At present, titanium-based catalysts are more representative to replace antimony-based catalysts. The activity is high, and the addition amount is only about 1-10ppm. If it is added in the continuous production of PET, the dispersion is not good, and the phenomenon of aggregation is easy to occur; the b value (blue to yellow) is high, due to the high activity. The reaction is violent, but the required viscosity cannot be reached within a certain period of time during polycondensation, and the relative residence time is long, so the b value is high

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