Alkyltin Stabilizer Composition for PVC Heat Stability
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Solution Overview
Problem
Halogen-containing polymers like PVC face decomposition and discoloration issues due to the toxicity, volatility, and inefficiency of existing alkyltin heat stabilizers, which pose challenges during processing and handling.
Innovation Solution
A stabilizer composition comprising specific blends of di-, mono-, and tri-methyltin compounds combined with a thioester, providing excellent heat stability and reduced toxicological impact through controlled volatility and higher efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If alkyltin stabilizers are used to prevent discoloration of halogen-containing polymers, then heat stability is improved, but toxicity increases
Solution Approach 1:
The patent changes the chemical parameters of the stabilizer by using specific alkyl groups (C12-C20) and controlled purity ranges of mono-, di-, and tri-alkyltin compounds to reduce toxicity while maintaining heat stability. The specific parameter changes include alkyl chain length and compositional ratios that lower toxicological impact.
Solution Approach 2:
The patent employs a composite stabilizer system comprising multiple alkyltin compounds (mono-, di-, and tri-alkyltin) in specific ratios, combined with mercaptoacetate esters. This composite approach allows the synergistic effect of different compounds to provide adequate long-term heat stability while reducing the toxicological impact compared to single-compound stabilizers.
2Reliability
If alkyltin stabilizers with higher tin content are used, then heat stability is improved, but volatility increases leading to higher personnel exposure
Solution Approach 1:
The patent optimizes the volatility parameter by selecting alkyl groups with 12-20 carbon atoms, which significantly reduces the volatility of the stabilizer compounds. This parameter change in the molecular structure directly addresses the harmful volatility effect while the compositional parameters (purity ranges and ratios) are adjusted to maintain heat stability.
3Object-affected harmful factors
If high purity mono-alkyltin compounds are used, then toxicity is reduced, but heat stability efficiency decreases
Solution Approach 1:
The patent creates a composite stabilizer system that combines high purity mono-alkyltin compounds (95-99.99% purity) with di- and tri-alkyltin compounds in specific ratios, along with mercaptoacetate esters. This composite formulation provides synergistic heat stability equivalent to or exceeding traditional stabilizers while maintaining the reduced toxicological impact of high purity mono-alkyltin compounds.
Solution Approach 2:
The patent merges multiple alkyltin compounds with different properties (mono-, di-, and tri-alkyltin) and combines them with mercaptoacetate esters to create a unified stabilizer system. This merging allows the composition to leverage the low toxicity of high purity mono-alkyltin while gaining the heat stability efficiency contributions from the other components.
Data Source
AI summary
A stabilizer composition having low volatility and high efficiency comprising: (i.) 25.000% to 99.997% by weight of at least one dimethyltin compound of formula (CH3)2Sn(S(CH2)mCOOR1)2 wherein R1 is a linear, branched or cyclic C10-C20 alkyl group and m is 1 or 2, optionally containing unsaturations in the form of double or triple bonds; (ii.) 0.001% to 50.000% by weight of at least one mono-methyltin compound of formula CH3Sn(S(CH2)nCOOR2)3 wherein R2 is a linear, branched or cyclic C10-C20 alkyl group and n is 1 or 2, optionally containing unsaturations in the form of double or triple bonds; (iii.) 0.001% to 10.000% by weight of at least one tri-methyltin compound of formula (CH3)3Sn(S(CH2)pCOOR3) wherein R3 is a linear, branched or cyclic C10-C20 alkyl group and p is 1 or 2, optionally containing unsaturations in the form of double or triple bonds; and (iv.) 0.001% to 15.000% by weight of at least one thioester of formula HS(CH2)qCOOR4 wherein R4 is a linear, branched or cyclic C10-C20 alkyl group and q is 1 or 2, optionally containing unsaturations in the form of double or triple bonds.