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Clear Semi-Crystalline Articles with Improved Heat Resistance

a semi-crystalline, heat-resistant technology, applied in packaging foodstuffs, packaging goods types, transportation and packaging, etc., can solve the problems of opacity in parts, difficult to mold or extrude even thin parts without thermal crystallization, and modified pct materials that provide little benefit in terms of heat-resistant performance, so as to improve heat-resistant performance and slow down the crystallization rate

Inactive Publication Date: 2013-08-22
EASTMAN CHEM CO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The patent describes a way to modify a material called TMCD that slows down the process of crystallization, which occurs when a material is heated or cooled. This modification allows for the creation of clear and durable articles that are better at withstanding heat compared to other materials. The process involves adding a specific chemical to the TMCD material, which prevents crystallization while still allowing for the material to crystallize when strained.

Problems solved by technology

On the other hand, unmodified PCT is known to crystallize extremely fast making it extremely difficult to mold or extrude even thin parts without thermal crystallization.
Thermal crystallization of PCT and other polyesters typically leads to opacity in parts.
Given the similar Tm and Tg to PET, these modified PCT materials provide little benefit in terms of heat resistance compared to PET and are typically more costly to produce.

Method used

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  • Clear Semi-Crystalline Articles with Improved Heat Resistance
  • Clear Semi-Crystalline Articles with Improved Heat Resistance
  • Clear Semi-Crystalline Articles with Improved Heat Resistance

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0496]This example illustrates that TMCD is more effective at reducing the crystallization rate of PCT than EG or IPA.

[0497]A variety of copolyesters were prepared as described below. These copolyesters were all made with 200 ppm dibutyl tin oxide as the catalyst in order to minimize the effect of catalyst type and concentration on nucleation during crystallization studies. The cis / trans ratio of the 1,4-cyclohexanedimethanol was 31 / 69 while the cis / trans ratio of the 2,2,4,4-tetramethyl-1,3-cyclobutanediol is reported in Table 1.

[0498]For purposes of this example, the samples had sufficiently similar inherent viscosities thereby effectively eliminating this as a variable in the crystallization rate measurements.

[0499]Crystallization half-time measurements from the melt were made at temperatures from 140 to 200° C. at 10° C. increments and are reported in Table 1. The fastest crystallization half-time for each sample was taken as the minimum value of crystallization half-time as a f...

example 1a

[0508]This example illustrates the preparation of a copolyester with a target composition of 80 mol % dimethyl terephthalate residues, 20 mol % dimethyl isophthalate residues, and 100 mol % 1,4-cyclohexanedimethanol residues (28 / 72 cis / trans).

[0509]A mixture of 56.63 g of dimethyl terephthalate, 55.2 g of 1,4-cyclohexanedimethanol, 14.16 g of dimethyl isophthalate, and 0.0419 g of dibutyl tin oxide was placed in a 500-milliliter flask equipped with an inlet for nitrogen, a metal stirrer, and a short distillation column. The flask was placed in a Wood's metal bath already heated to 210° C. The stirring speed was set to 200 RPM throughout the experiment. The contents of the flask were heated at 210° C. for 5 minutes and then the temperature was gradually increased to 290° C. over 30 minutes. The reaction mixture was held at 290° C. for 60 minutes and then vacuum was gradually applied over the next 5 minutes until the pressure inside the flask reached 100 mm of Hg. The pressure inside ...

example 1b

[0510]This example illustrates the preparation of a copolyester with a target composition of 100 mol % dimethyl terephthalate residues, 20 mol % ethylene glycol residues, and 80 mol % 1,4-cyclohexanedimethanol residues (32 / 68 cis / trans).

[0511]A mixture of 77.68 g of dimethyl terephthalate, 50.77 g of 1,4-cyclohexanedimethanol, 27.81 g of ethylene glycol, and 0.0433 g of dibutyl tin oxide was placed in a 500-milliliter flask equipped with an inlet for nitrogen, a metal stirrer, and a short distillation column. The flask was placed in a Wood's metal bath already heated to 200° C. The stirring speed was set to 200 RPM throughout the experiment. The contents of the flask were heated at 200° C. for 60 minutes and then the temperature was gradually increased to 210° C. over 5 minutes. The reaction mixture was held at 210° C. for 120 minutes and then heated up to 280° C. in 30 minutes. Once at 280° C., vacuum was gradually applied over the next 5 minutes until the pressure inside the flask...

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Abstract

The present invention relates to a clear, semicrystalline article comprising a polyester comprising terephthalic acid residues as the dicarboxylic acid component, and 1 to 15 mole % of 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues and 85 to 99 mole % of 1,4-cyclohexanedimethanol residues as the glycol component. The article may be in the form of a film or sheet, a bottle, or a fiber. The article, when produced by a process involving strain-induced crystallization, is characterized with high crystallinity.

Description

FIELD OF THE INVENTION[0001]The present invention generally relates to clear semi-crystalline articles made from polyesters comprising terephthalic acid, or an ester thereof, or mixtures thereof; 1 to 15 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues and 85 to 99 mole % 1,4-cyclohexanedimethanol residues. These polyesters have a surprising combination of a certain crystallization rate along with a certain melting temperatures (Tm) and certain glass transition temperatures (Tg). These polyesters are useful in preparing clear semi-crystalline articles with improved heat resistance by strain induced crystallization processes known in the art.BACKGROUND OF THE INVENTION[0002]To date, copolyester compositions comprising terephthalic acid or an ester thereof or mixtures thereof, 2,2,4,4-tetramethyl-1,3-cyclobutanediol (TMCD) residues and 1,4-cyclohexanedimethanol (CHDM) residues have been focused primarily for use in the injection molding and extrusion of amorphous articles even ...

Claims

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Application Information

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IPC IPC(8): C08G63/199C08L69/00B65D23/00C08L67/02
CPCC08L67/02C08G63/199C08L2201/10C08L2203/10C08L2205/02
Inventor CRAWFORD, EMMETT DUDLEYDONELSON, MICHAEL EUGENE
Owner EASTMAN CHEM CO
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