Low Migration DOTP Plasticizer via Mixed-Chain Esterification
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Solution Overview
Problem
Di-2-ethylhexyl terephthalate (DOTP) plasticizers used in PVC products exhibit poor compatibility and high migration, leading to surface precipitation issues, which are costly to address with existing solutions such as additional components or acrylic layers.
Innovation Solution
A method involving an esterification reaction between terephthalic acid and 2-ethylhexanol, incorporating short and long chain alcohols to modify DOTP, resulting in a low migration plasticizer with improved compatibility and processability, achieved through specific reaction conditions and purification steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If DOTP plasticizer is used in PVC products, then environmental friendliness and non-toxicity are improved, but compatibility with PVC deteriorates causing surface precipitation
Solution Approach 1:
The patent modifies the chemical structure of DOTP by introducing ester groups from short chain alcohols (4-6 carbon atoms) and long chain alcohols (9-13 carbon atoms) to create low migration DOTP. This structural parameter change improves compatibility with PVC while maintaining the environmental benefits of DOTP, resolving the contradiction between toxicity and compatibility.
Solution Approach 2:
The invention creates a composite plasticizer structure by combining DOTP with ester groups derived from multiple alcohol components. This composite structure integrates the non-toxic properties of DOTP with the compatibility-enhancing characteristics of the ester groups, simultaneously achieving both improved toxicity profile and compatibility.
2Stability of the object's composition
If additional components (e.g., citrate) are added to inhibit DOTP migration, then precipitation phenomenon is improved, but manufacturing cost increases
Solution Approach 1:
The patent extracts and eliminates the need for additional migration-inhibiting components by incorporating the compatibility-enhancing ester groups directly into the DOTP molecular structure. This removes the requirement for separate additives like citrate, reducing manufacturing complexity and cost while maintaining precipitation resistance.
Solution Approach 2:
The invention merges the functions of DOTP (environmental friendliness) and migration inhibitors (compatibility improvement) into a single modified DOTP molecule. By combining these functions into one substance rather than using multiple separate components, the patent reduces manufacturing cost and simplifies the formulation process.
3Stability of the object's composition
If acrylic layer is applied onto product surface to inhibit DOTP migration, then precipitation phenomenon is improved, but process complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the need for post-processing acrylic coating by incorporating compatibility-enhancing ester groups directly into the DOTP structure. This removes the entire coating process step, significantly reducing process complexity while maintaining the ability to prevent surface precipitation.
4Ease of operation
If DOTP is used to increase plasticity and processability of PVC, then softness and elasticity are improved, but migration to surface occurs affecting appearance and hand feel
Solution Approach 1:
The patent changes the molecular parameters of DOTP by adding ester groups from short and long chain alcohols. This structural modification reduces migration tendency while preserving the plasticizing properties that provide softness, elasticity, and processability to PVC, thus resolving the contradiction between processability and migration resistance.
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
The resulting low migration plasticizer demonstrates high purity, low color number, and reduced surface migration, enabling higher usage amounts without affecting product appearance or hand feel, while simplifying production and reducing costs.
Implementation Method 1
a synthesis step of adding at least one short chain alcohol component having 4 to 6 carbon atoms and at least one long chain alcohol component having 9 to 13 carbon atoms in an esterification reaction between terephthalic acid and 2-ethylhexanol
Implementation Method 2
a first dealcoholization step of preliminarily reducing an alcohol content of the crude ester product under a temperature from 180° C. to 200° C. and a pressure from 80 mbar to 500 mbar
Data Source
AI summary
A method for preparing a low migration plasticizer of di-2-ethylhexyl terephthalate is provided. The method includes a step of adding a short chain alcohol component having 4 to 6 carbon atoms and a long chain alcohol component having 9 to 13 carbon atoms in an esterification reaction between terephthalic acid and 2-ethylhexanol, so as to obtain a modified di-2-ethylhexyl terephthalate including residues derived from the short chain alcohol component and the long chain alcohol component. The esterification reaction is carried out under a temperature from 30° C. to 225° C. and a pressure from 80 mbar to 1033 mbar.