Methyltin Mercaptide Derivative for High-Temperature Calendering
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Solution Overview
Problem
Methyltin mercaptides used as heat stabilizers in plastics processing have low boiling points and high volatility, making them unsuitable for high-temperature and high-speed calendering processes due to reduced reactivity.
Innovation Solution
A methyltin mercaptide derivative with a high boiling point is synthesized by reacting isooctyl mercaptopropionate with a methyltin chloride aqueous solution, followed by pH regulation and staged esterification, resulting in a compound suitable for high-temperature and high-speed calendering processes with improved reactivity and environmental safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional methyltin mercaptides are used as heat stabilizers, then they provide heat stabilization function, but they have low boiling point and high volatility causing reduced reactivity in high-temperature calendering
Solution Approach 1:
The patent changes the molecular structure parameters of the methyltin mercaptide by introducing a propionate group at the sulfur atom (replacing conventional thioglycolate structure). This structural parameter change increases the molecular weight and boiling point, while the patent optimizes the esterification reaction conditions (catalyst selection, temperature control, pH regulation) to ensure complete reaction and high yield, thereby maintaining reactivity despite the higher boiling point
2Object-generated harmful factors
If methyltin chloride aqueous solution is added dropwise to isooctyl mercaptopropionate, then side reactions and acid mist formation are reduced, but the reaction requires precise pH control and staged processing
Solution Approach 1:
The patent performs preliminary action by pre-adjusting the pH of the isooctyl mercaptopropionate solution before adding the methyltin chloride aqueous solution. This preliminary pH adjustment (to weak acidic or weak basic range) prevents excessive acid mist formation during the reaction. The patent also divides the reaction into staged processing with intermediate pH adjustments, which simplifies the control of each individual step while achieving the overall goal of reducing harmful emissions
Solution Approach 2:
The patent uses pH regulation (through addition of base or buffering) as an intermediary control mechanism to mediate between the reactive methyltin chloride and isooctyl mercaptopropionate. By controlling the pH environment, the patent reduces the formation of acid mist (harmful factor) while maintaining reaction efficiency. The pH control acts as a mediator that balances reaction progress with emission reduction
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 high-boiling-point methyltin mercaptide derivative achieves up to 96% yield, replacing conventional methyltin isooctyl thioglycolates, and is more environmentally friendly and reactive, enabling efficient use in high-temperature and high-speed calendering processes.
Implementation Method 1
adding isooctyl mercaptopropionate to a reactor, adding dropwise an aqueous solution of methyltin chloride, stirring and allowing for a complete reaction
Implementation Method 2
allowing the product to stand until phases are separated, collecting and washing an organic phase
Implementation Method 3
collecting an organic product obtained from step b), and evaporating the product under reduced pressure to yield the compound
Data Source
AI summary
A compound represented by formula I or II and a method for preparing the same. The method includes: a) adding isooctyl mercaptopropionate to a reactor, adding dropwise an aqueous solution of methyltin chloride, stirring and allowing for a complete reaction, and adding aqueous ammonia, an aqueous solution of sodium hydroxide, an aqueous solution of sodium bicarbonate, an aqueous solution of sodium carbonate, or a solution of an organic base to regulate the pH value of a resulting mixture from a starting value of between 2 and 8 to an end value of between 6 and 10 for a primary stage of esterification; and b) allowing a product obtained from step a) to proceed to a secondary stage of the esterification, allowing the product to stand until phases are separated, collecting and washing an organic phase using deionized water, allowing a resulting mixture to stand until phases are separated.