Polymer Latex Chain Transfer Strategy for Strength and Elongation
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Solution Overview
Problem
Existing polymer latexes used in coatings and carpet backing applications lack sufficient mechanical properties, such as high elongation at break and tensile strength, which are essential for maintaining binding strength and resistance to moisture and ink splitting forces during printing processes.
Innovation Solution
A process involving the combination of hydroperoxide and sulfur-containing chain transfer agents during the polymerization of ethylenically unsaturated aromatic and conjugated diene monomers to produce a polymer latex with improved mechanical properties, specifically using tert-butyl hydroperoxide and tert-dodecyl mercaptan as preferred chain transfer agents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional polymer latexes are used in coatings and carpet backing applications, then basic binding properties are provided, but sufficient mechanical properties such as high elongation at break and tensile strength are lacking
Solution Approach 1:
The patent combines hydroperoxide chain transfer agent and sulfur-containing chain transfer agent in the polymerization process to achieve synergistic effects. This combination produces a polymer latex with both high elongation at break and high tensile strength at break, resolving the contradiction between strength and reliability under various conditions including moisture exposure and ink splitting forces.
Solution Approach 2:
The patent modifies the polymerization parameters by introducing specific chain transfer agents (hydroperoxide and sulfur-containing compounds) in controlled amounts. This changes the molecular weight distribution and polymer structure, resulting in improved mechanical properties including tensile strength and elongation, while maintaining reliability under moisture and printing conditions.
2Strength
If polymer latex with high tensile strength is produced, then mechanical strength is improved, but elongation at break may be compromised
Solution Approach 1:
The simultaneous use of hydroperoxide and sulfur-containing chain transfer agents creates a synergistic effect that produces polymer chains with both high strength and high elongation. The hydroperoxide agent contributes to tensile strength while the sulfur-containing agent maintains elongation at break, resolving the typical trade-off between these two mechanical properties.
3Reliability
If polymer latex is used in paper coating composition, then binding properties are provided, but resistance to ink splitting forces during multiple printing stations is insufficient
Solution Approach 1:
The patent optimizes the polymerization parameters by controlling the type and amount of chain transfer agents used. This produces a polymer latex with specific molecular weight distribution and crosslinking density that enhances both binding strength and piling resistance, allowing the coating to withstand ink splitting forces during commercial offset printing processes with multiple printing stations.
4Strength
If polymer latex provides high wet and dry binding strength, then binding performance is improved, but flexibility for ease of installation and pattern matching may be reduced
Solution Approach 1:
The combination of hydroperoxide and sulfur-containing chain transfer agents produces a polymer with optimized molecular structure that balances strength and flexibility. The resulting polymer latex provides high wet and dry binding strength while maintaining sufficient flexibility for ease of carpet installation and pattern matching, resolving the contradiction between these opposing requirements.
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 polymer latex exhibits superior binding effects with high elongation and tensile strength, enhancing the performance in paper coatings, carpet backing, and fiber fabric pre-impregnation processes by providing improved wet and dry binding strength, piling resistance, and retention of strength under moisture exposure.
Implementation Method 1
the combination of a hydroperoxide chain transfer agent and a sulfur-containing chain transfer agent allows the polymerization of ethylenically unsaturated aromatic monomer and conjugated diene monomer to provide a polymer latex with improved mechanical properties
Implementation Method 2
polymerizing one or more ethylenically unsaturated aromatic monomers and one or more conjugated diene monomers in the presence of hydroperoxide chain transfer agent and sulfur-containing chain transfer agent
Data Source
AI summary
The present invention relates to a process for preparing a polymer latex that includes polymerizing one or more ethylenically unsaturated aromatic monomers and one or more conjugated diene monomers in the presence of a hydroperoxide chain transfer agent and sulfur-containing chain transfer agent, wherein the sulfur-containing chain transfer agent is added after the hydroperoxide chain transfer agent. It further relates to the polymer latex thus obtained, to a composition comprising the polymer latex and to the use of the polymer latex or polymer latex composition in a carpet backing, paper coating, or fiber fabric pre-impregnation process.