Transesterification of Reclaimed Carpet Polyester

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Solution Overview

Problem

The recycling of terephthalate polyester resins is hindered by hydrolysis when heated in the presence of moisture, leading to reduced molecular weight, and there is a lack of economically viable methods for recycling polyester-based carpets, resulting in significant waste disposal challenges and energy costs.

Innovation Solution

A process involving the reaction of reclaimed carpet material comprising a polyester component with an alcohol having 6 to 20 carbon atoms, under conditions effective to produce a terephthalate ester and diol, where 15-40% of the terephthalate ester and substantially all diol are derived from the polyester component, utilizing a catalyst at temperatures between 160° C to 260° C.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If polyester is heated in the presence of moisture during reprocessing, then the processing can proceed, but the polyester hydrolyzes and molecular weight is severely reduced

Engineering Contradiction:

Improveprocessing temperatureVSAvoidmolecular weight integrity

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The patent applies preliminary anti-action by adding moisture scavengers (molecular sieves, activated alumina, or anhydrous salts) to the polyester processing system before heating occurs. These agents preemptively remove moisture from the environment, preventing hydrolysis before it can compromise the polyester chains during high-temperature processing.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The patent uses moisture scavengers as intermediary substances that mediate between the polyester and water molecules. These intermediaries (such as molecular sieves or activated alumina) selectively bind water molecules, preventing them from interacting with and hydrolyzing the polyester ester linkages during processing.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If conventional transesterification process is used to produce terephthalate esters from reclaimed carpet, then the reaction can proceed, but the process is slow and economically undesirable

Engineering Contradiction:

Improveprocess feasibilityVSAvoidreaction rate

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The patent applies parameter changes by conducting the transesterification reaction at elevated temperatures (150-200°C) and using excess alcohol (6-20 carbon atoms) as both reactant and solvent. These parameter modifications significantly accelerate the reaction rate compared to conventional conditions, making the process economically viable while maintaining feasibility.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements continuity of useful action by using the alcohol reactant in large excess (at least 5:1 molar ratio), which drives the equilibrium continuously toward product formation. The excess alcohol also serves as the reaction medium, eliminating the need for separate solvent removal steps and maintaining continuous productive action throughout the process.

Inventive Principle:

Principle #20Continuity of useful action

3Ease of manufacture

If polyester-based carpets are disposed of conventionally, then waste disposal is simple, but significant waste and energy costs are incurred

Engineering Contradiction:

Improvedisposal simplicityVSAvoidmaterial waste

Core Design Contradiction:

Ease of manufactureVSLoss of substance

Solution Approach 1:

The patent applies discarding and recovering by collecting post-consumer polyester carpets that would otherwise be discarded as waste, and converting them through transesterification into valuable terephthalate esters and diols. This process recovers the chemical value embedded in the discarded material, transforming waste into economically useful products.

Inventive Principle:

Principle #34Discarding and recovering

Solution Approach 2:

The patent changes the state and value of the discarded polyester material by subjecting it to chemical transformation parameters (heat, catalyst, alcohol solvent) that convert the low-value waste polyester into high-value liquid ester products, thereby eliminating the need for energy-intensive incineration or landfilling.

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This process efficiently recycles terephthalate ester and diol from reclaimed carpet materials, reducing waste and energy costs while maintaining the integrity of the polyester component, enabling the reuse of polyester-based materials.

Implementation Method 1

Methodology Applied

Scientific EffectTransesterification: Chemical Bonding

Implementation Method 2

utilizing a catalyst at temperatures between 160° C to 260° C

Methodology Applied

Scientific EffectCatalysis: Catalysis

Data Source

PatentUS9981902B2Process for production of an ester and diol from reclaimed carpet material

Publication Date: 2018.05.29 COLUMBIA INSURANCE CO

AI summary

The current invention pertains to a process for producing a terephthalate ester comprising: providing reclaimed carpet material comprising a polyester component; and reacting the polyester component with an alcohol having from 6 to 20 carbon atoms and under conditions effective to produce a terephthalate ester; wherein 15-40% of the mass of the terephthalate ester is derived from the polyester present in the reclaimed carpet material.