Conjugated Diene Polymer Emulsifier Segmentation

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Solution Overview

Problem

Conjugated diene-based polymers used in ABS graft copolymers often contain high amounts of emulsifiers and additives that generate gas during molding, leading to poor surface properties and thermal stability in thermoplastic resin compositions.

Innovation Solution

A method for preparing conjugated diene-based polymers by continuously adding monomers to a reactor with divided emulsifier addition before and during polymerization, reducing the amount of emulsifier and acid added, which minimizes gas generation and improves polymerization stability, resulting in improved appearance quality and thermal stability of the final product.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional emulsifier addition methods are used during polymerization, then polymerization stability is maintained, but residual emulsifier and acid in the polymer increase, leading to gas generation during molding and poor surface properties

Engineering Contradiction:

Improvepolymerization stabilityVSAvoidgas generation during molding

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent divides emulsifier addition into multiple stages: initial addition before polymerization, intermediate addition at 30-70% conversion, and optional final addition at 80-90% conversion. This segmented approach maintains polymerization stability during each stage while minimizing total emulsifier residue that causes gas generation during molding.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements periodic emulsifier addition based on polymerization conversion rate thresholds (30%, 70%, 80-90%). This periodic action ensures stability is maintained when needed while avoiding excessive emulsifier accumulation that leads to gas generation and surface defects.

Inventive Principle:

Principle #19Periodic action

2Reliability

If high amounts of emulsifier are added during polymerization, then polymerization stability is improved, but the amount of residual emulsifier and acid increases, resulting in poor appearance quality of the final product

Engineering Contradiction:

Improvepolymerization stabilityVSAvoidappearance quality

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent segments emulsifier addition into controlled stages with specific conversion rate triggers, preventing excessive emulsifier accumulation while maintaining stability. This results in lower residual emulsifier content that causes fewer surface defects and improves appearance quality.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the parameter of emulsifier addition timing from continuous or single-stage to multi-stage based on polymerization conversion rate. This parameter change optimizes the balance between maintaining polymerization stability and minimizing residual emulsifier that affects appearance quality.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If conventional continuous emulsifier addition is used, then polymerization conversion rate is maintained, but gas generation during molding increases due to accumulated additives

Engineering Contradiction:

Improvepolymerization conversion rateVSAvoidgas generation from additives

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent uses periodic emulsifier addition at specific conversion rate intervals (30%, 70%, 80-90%) rather than continuous addition. This maintains polymerization conversion rate while preventing excessive additive accumulation, thereby reducing gas generation during molding.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent segments the continuous emulsifier addition process into discrete stages tied to conversion rate milestones. This segmentation allows conversion rate maintenance while controlling total additive content to minimize gas generation during subsequent molding operations.

Inventive Principle:

Principle #1Segmentation

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 method significantly reduces residual emulsifier and acid in the polymer, resulting in reduced gas generation during molding, leading to thermoplastic resin compositions with excellent surface properties and thermal stability.

Implementation Method 1

ABS graft copolymers are prepared by graft-polymerizing styrene and acrylonitrile to a butadiene polymer by emulsion polymerization

Methodology Applied

Scientific EffectEmulsion polymerization:

Implementation Method 2

polymerization by initiating polymerization while continuously adding conjugated diene-based monomers

Methodology Applied

Scientific EffectFree radical polymerization:

Data Source

PatentEP3854822B1Method of preparing conjugated diene-based polymer and method of preparing graft copolymer comprising same

Publication Date: 2024.10.30 LG CHEM LTD

AI summary

The present invention relates to a method for preparing a conjugated diene-based polymer, which includes a step of preparing a conjugated diene-based polymer by initiating and carrying out polymerization while continuously adding conjugated diene-based monomers to a reactor, and in which an emulsifier is dividedly added before the initiation of the polymerization and when a polymerization conversion rate of 31% to 80% is reached. More particularly, the present invention relates to: a method for preparing a conjugated diene-based polymer and a method for preparing a graft copolymer including the method for preparing a conjugated diene-based polymer, by which a total usage amount of an emulsifier can be reduced.