Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Reexamination Certificate
2001-05-14
2002-05-21
Acquah, Samuel A. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
C528S180000, C528S212000, C528S275000, C528S279000, C528S283000, C528S285000, C528S302000, C528S308600, C528S481000, C528S503000, C524S711000, C524S783000
Reexamination Certificate
active
06392005
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a manufacturing method which effectively restrains the production of the cyclic oligomer in ester chips and further decreases the amount of regenerated cyclic oligomer at the melt processing stage by adding the additive, during the process of manufacturing polyethylene terephthalate, with the following structure:
the polymer of the present invention can be further processed to manufacture polyester products such as bottles, fibers, film, and laminates. The examples of polyester bottles mentioned in the present invention are given to illustrate but not to limit the invention.
2. Problems to be Solved by the Present Invention
Polyethylene terephthalate (PET) is widely used in manufacturing products such as polyester bottles, polyester fiber, polyester laminates, and polyester films owing to its good physical characters and capability of being recycled. Particularly, polyester bottles are massively used in packaging various kinds of food, beverage, and detergent, which contributes to the sky-rocket growth both in its consumption and in its production.
During the process of manufacturing PET, the cyclic oligomer, mainly cyclic trimer, is produced from side reaction. This sort of oligomer is white crystallized powder with a melting point of 319 .degree.C. so as to pollute the mold while processed; consequently, the production line needs to be shut down and cleaned.
In addition, PET can be manufactured into various kinds of bottle while applied to food packaging such as the bottle for heat resistance, in which the temperature of the content is above 80 .degree.C., or into the bottom plate of packaging film which can be applied to a microwave oven or an oven, or into PET bottles used as beer containers which need to be pasteurized. The above said applications put PET high molecular compound in an environment of high temperature, which causes the residual oligomer, particularly cyclic oligomer (mainly cyclic trimer), in the high molecular compound to have a potential to transfer to the packaged content so as to hazard human health.
The said oligomer is either produced from the side reaction of PET synthesis procedure or regenerated from processing procedure.
To solve said problems, the present invention adds a compound containing phosphorus which effectively restrains the production of the cyclic oligomer produced from the side reaction during PET synthesis procedure and further effectively restrains the regeneration of cyclic oligomer during processing procedure.
DESCRIPTION OF PRIOR ARTS
Japan Publication No.12-219731 discloses that while the ratio of mole number of SO
3
X compound to that of metal such as antimony, or titanium, or germanium, or zink is higher than 0.01, the produced cyclic oligomer content in the melted state polymerized PET can be effectively restrained.
Japan Publication No.12-204229 discloses that to add 200~10,000 ppm of alkali metals or alkaline-earth metals such as calcium acetate or magnesium benzoate into the PET containing germanium catalyst can effectively restrain the production of cyclic oligomer.
Japan Publication No.12-219729 discloses that while the antimony element is 0.5×10
−4
~×10
−4
moles relative to the acid component of PET, the phosphoric acid is added until the phosphorus element is 1×10
−4
~5×10
−4
moles relative to the acid component of PET, wherein the mole ratio of antimony element to phosphorus element is 1~3, so as to effectively restrain the cyclic trimer down to 0.35 weight % or lower.
Japan Publication No.12-198937 discloses that while the germanium element is 0.5×10
−4
~3×10
−4
moles relative to the acid component of PET, the phosphoric acid is added until the phosphorus element is 1×10
−4
~7×10
−4
moles relative to the acid component of PET, wherein the mole ratio of germanium element to phosphorus element is greater than 1.6, so as to effectively restrain the cyclic trimer down to below 0.4 weight %.
Japan Publication No.12-7767 discloses that the intrinsic viscosity of raw chips before solid state polymerization is between 0.45~0.65 dl/g. While the ethylene glycol end group content is between 90~140 equivalent/10
−6
gram and the pressure is below 200 Pa and the temperature is 230 .degree.C. and the solid state polymerization reaction time is 20 hours, the decreasing rate of cyclic trimer is bigger than 300 ppm/hour. While the ethylene glycol end group content is lower than 90 equivalent/10
−6
gram, the decreasing rate of cyclic trimer is lower; however, solid state polymerization rate is bigger. While the ethylene glycol end group content is higher than 140 equivalent/10
−6
gram, the effect is opposite. The control method on the ethylene glycol end group content is to adjust the conversion rate of esterification such as to adjust the mole ratio of ethylene glycol to terephthalic acid, esterification temperature, pressure, residence time, or to adjust polycondensation reaction temperature, time, vacuum intensity, quantity of added catalyst, or further to adjust the intrinsic viscosity of polyester raw chips.
Japan Publication No.12-80284 discloses that PET chips proceeds melt blending with heat plasticized resin masterbatch which contains one of the following three structural compounds: alkylene oxide, or polyalkylene glycol, or bisphenol. The obtained resin is melted at 280 .degree.C. for five minutes. The analyzed cyclic trimer content of the product is lower than 0.5 weight % which is lower than that of the PET obtained from the process without said structural compounds.
Japan Publication No.11 -181257 and Japan Publication No.9-151308 disclose that while the intrinsic viscosity is 0.7~0.9 dl/g, and the DEG content is 1~3 mole %, and the cyclic trimer content of ester chips is lower than 0.4 wt %, add a slight amount of one of the following three compounds: polyethylene, or polypropylene, or polyurethane to appropriately accelerate crystallization rate lest the constant heating temperature should be increased, due to the crystallization speed being too slow while blow-molded, consequently the cyclic trimer is produced so much as to pollute the mold. The melted ester chip is analyzed by a differential scan measuring instrument. The pollution of white powder is effectively restrained while the crystallization peak temperature for temperature increasing stage is between 155~168 .degree.C. and that for temperature decreasing stage is between 165~180 .degree.C.
Japan Publication No.11-80520 discloses that the situation of pollution on mold during blow-molding is improved while the amide compound, with a content of {fraction (1/300)}~½ of cyclic trimer wt %, is added into solid state polymerized PET.
Japan Publication No.10-259245 discloses that in PET melt polymerization process, antimony acetate is added. While the intrinsic viscosity reaches 0.35 dl/g or higher, phosphoric acid or phosphoric acid monoester is added; the production of cyclic trimer decreases when melt molded.
Japan Publication No.10-1 68168 discloses a process of producing the copolymer using terephthalic acid, ethylene glycol, and DEG with 2~4 wt % based on PET. The time point of the addition of amorphous state germanium dioxide catalyst is while the esterification ratio reaches above 90 percent so as to reduce the production of formaldehyde, acetaldehyde, and cyclic trimer while molded.
Japan Publication No.9-221540 discloses that while the DEG content of PET chips is 1~4 mole %, and the intrinsic viscosity is 0.60~0.90 dl/g, and the phosphoric acid content relative to PET is 5~25 ppm, and germanium content of germanium calyst relative to PET is 20~60 ppm, and the mole ratio of germanium element content to phosphorus element content is between 0.4~1.5, the acetaldehyde content of solid state polymerized polyester chips is below 4 ppm and the cyclic trimer content is lower than 0.5 wt %.
Japan Publication No.9-296029 and Japan Publication No 10-110026
Acquah Samuel A.
Nan Ya Plastics Corporation
Stevens Davis Miller & Mosher LLP
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