Conjugated Diene Polymerization via Segmented Feeding and Dimer Acid Emulsifier
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Solution Overview
Problem
Conventional methods for preparing conjugated diene-based polymers used in thermoplastic resins face challenges in improving impact strength and surface reflection haze while reducing gas generation during injection.
Innovation Solution
A method involving the injection of a conjugated diene-based monomer, a dimer acid saponified material, and a polymerization initiator in one batch, followed by incremental injections of the monomer and an emulsifier based on polymerization conversion ratios, to achieve a polymerization conversion ratio of 90 to 99%. This approach enhances the standard deviation of the particle diameter, thereby improving impact strength and surface reflection haze while minimizing gas generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional polymerization methods are used, then the polymerization process is simple, but the impact strength and surface reflection haze are poor and gas generation is high
Solution Approach 1:
The polymerization process is divided into multiple stages with different monomer feeding strategies. The first stage uses continuous feeding to create a core structure, while the second stage uses batch feeding to form a shell layer, creating a core-shell structure that improves impact strength and surface properties
Solution Approach 2:
Different regions of the polymer particle are given different compositions and properties. The core region has different monomer composition and crosslinking density compared to the shell region, creating local quality variations that enhance overall performance including impact strength and surface reflection haze
2Manufacturing precision
If conventional polymerization methods are used, then the process is fast, but surface reflection haze and resin quality are poor
Solution Approach 1:
The polymerization is segmented into two distinct stages with different feeding modes. The first stage rapidly consumes monomer to build core structure, while the second stage slowly adds remaining monomer to form a uniform shell, improving surface reflection haze while maintaining overall productivity
Solution Approach 2:
The core structure is prepared in advance during the first polymerization stage before the shell formation begins. This preliminary action allows the shell to form uniformly around a stable core, improving surface quality without significantly extending total production time
3Object-generated harmful factors
If conventional polymerization methods are used, then the emulsifier amount is low, but gas generation during injection is high
Solution Approach 1:
A significant amount of emulsifier is added at the beginning of the first polymerization stage before most monomer is consumed. This preliminary addition ensures sufficient emulsifier is present to stabilize the system and prevent gas generation during subsequent processing, without requiring excessive emulsifier throughout the entire process
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 effectively enhances the impact strength and surface reflection haze of thermoplastic resins and reduces gas generation during injection, leading to improved resin quality.
Implementation Method 1
initiating polymerization reaction (S1)
Implementation Method 2
0.1 to 5 parts by weight of a dimer acid saponified material
Data Source
AI summary
The present invention relates to a method for preparing a conjugated diene-based polymer, characterized in using a dimer acid saponified material as an emulsifier in a polymerization initiation step and injecting a monomer and the emulsifier in three or more installments after initiating polymerization, and the conjugated diene-based polymer prepared by the preparation method of the present invention has excellent physical properties such as impact strength and reflection haze.