Modified Polyester Resin Side-Chain Reactivity Without Gelation
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Solution Overview
Problem
Existing polyester resins face challenges in achieving high molecular weight while maintaining excellent reactivity with curing agents and storage stability, particularly due to risks of gelation and molecular weight loss during polymerization and depolymerization reactions.
Innovation Solution
A modified copolymerized polyester resin with unsaturated polyvalent carboxylic acid added to the side chain, incorporating specific copolymerization components such as alicyclic structures, continuous methylene groups, and acyclic aliphatic copolymerization components with tertiary carbon atoms, allowing for efficient radical addition reactions and high molecular weight without gelation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a branched structure is introduced into the polyester resin to increase terminal carboxyl group concentration, then reactivity with curing agent is improved, but gelation during polymerization occurs and high molecular weight cannot be achieved
Solution Approach 1:
The invention introduces a branched structure only at the terminal of the polyester resin molecule rather than throughout the entire chain. This localized branching increases terminal carboxyl group concentration and reactivity with curing agents while avoiding the gelation problems associated with extensive branching throughout the polymer structure.
Solution Approach 2:
The polyester resin structure is segmented into a straight-chain main body and a branched terminal portion. The main chain maintains high molecular weight and structural stability, while the terminal branches provide increased carboxyl group concentration for improved curing reactivity.
2Reliability
If a branched structure is introduced into the polyester resin to increase terminal hydroxyl group concentration, then reactivity with curing agent is improved, but gelation during polymerization occurs and high molecular weight cannot be achieved
Solution Approach 1:
The invention introduces a branched structure only at the terminal of the polyester resin molecule rather than throughout the entire chain. This localized branching increases terminal carboxyl group concentration and reactivity with curing agents while avoiding the gelation problems associated with extensive branching throughout the polymer structure.
Solution Approach 2:
The polyester resin structure is segmented into a straight-chain main body and a branched terminal portion. The main chain maintains high molecular weight and structural stability, while the terminal branches provide increased carboxyl group concentration for improved curing reactivity.
3Reliability
If copolymerization is performed to increase terminal group concentration, then reactivity is improved, but high molecular weight cannot be achieved
Solution Approach 1:
The invention introduces a branched structure only at the terminal of the polyester resin molecule rather than throughout the entire chain. This localized branching increases terminal carboxyl group concentration and reactivity with curing agents while avoiding the gelation problems associated with extensive branching throughout the polymer structure.
4Reliability
If depolymerization reaction is performed to add oligomer compound, then hydroxyl group concentration is increased, but molecular weight decreases and cannot be controlled in prescribed range
Solution Approach 1:
The invention performs copolymerization during the initial polyester resin synthesis to incorporate branching functionality into the polymer structure from the beginning. This preliminary action allows controlled formation of terminal branches with desired carboxyl group concentration while maintaining molecular weight within the prescribed range, avoiding the uncontrolled molecular weight reduction that occurs with post-polymerization depolymerization methods.
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 modified copolymerized polyester resin exhibits excellent reactivity with various curing agents, forms stable aqueous dispersions, and maintains good storage stability without molecular weight loss, facilitating the production of high-quality coatings and adhesives.
Implementation Method 1
a modified copolymerized polyester resin (B) having a structure in which a copolymerized polyester resin (A) has an unsaturated polyvalent carboxylic acid added to a side chain
Data Source
AI summary
[Problem] The present invention aims to provide a high-molecular-weight modified copolymerized polyester resin that has a reactive functional group at a site other than the terminals of the molecular chain thereof, has an excellent reactivity with a curing agent (such as an epoxy resin or an isocyanate compound), and can be used to form an organic-solvent-and-emulsifier-free water dispersion having excellent storage stability.[Solution] A modified copolymerized polyester resin (B) having a structure in which a copolymerized polyester resin (A) has an unsaturated polyvalent carboxylic acid added to a side chain thereof, and the copolymerized polyester resin (A) contains, as copolymerization components, at least one member selected from the group consisting of: a copolymerization component having an alicyclic structure (component x); a copolymerization component having six or more continuous methylene groups (component y); and an acyclic aliphatic copolymerization component having a tertiary carbon atom and a molecular weight of more than 100 (component z).