Side-Chain Modified Copolymerized Polyester Resin Without Gelation
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Solution Overview
Problem
Existing polyester resins face challenges such as increased risk of gelation during polymerization, inability to achieve high molecular weight, and difficulty in controlling molecular weight, which affect their reactivity and storage stability, especially when used in water dispersions.
Innovation Solution
A modified copolymerized polyester resin is developed with specific structural components, including an unsaturated polyvalent carboxylic acid added to the side chain, and copolymerization components with alicyclic structures, continuous methylene groups, and acyclic aliphatic copolymerization components, allowing for efficient radical addition reactions and high molecular weight without gelation, enhancing reactivity and storage stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a branched structure is introduced into the polymer molecular chain to increase terminal group concentration, then reactivity with curing agent is improved, but the risk of gelation during polymerization increases and high-molecular-weight polyester resin cannot be achieved
Solution Approach 1:
The patent introduces a branched structure only at the terminal portion of the polymer chain rather than throughout the entire molecular chain. This localized branching increases terminal group concentration for improved curing reactivity while avoiding the gelation risk associated with widespread branching in the molecular chain.
Solution Approach 2:
The patent segments the polymer structure into a linear main chain and a branched terminal portion. This segmentation allows the terminal groups to provide high reactivity for curing while the linear main chain maintains high molecular weight and prevents gelation during polymerization.
2Reliability
If a branched structure is introduced into the molecular terminal to increase carboxyl group concentration, then reactivity with curing agent is improved, but high-molecular-weight polymers inevitably have low terminal group concentration
Solution Approach 1:
The patent performs preliminary branching at the terminal portion during the polymerization process, creating a structure where terminal groups are pre-concentrated. This preliminary action ensures high terminal group concentration is achieved without requiring post-polymerization modifications that would reduce molecular weight.
3Reliability
If depolymerization reaction is performed to increase hydroxyl group concentration, then reactivity is improved, but molecular weight decreases and cannot be controlled in prescribed range
Solution Approach 1:
The patent introduces hydrophilic groups and branches the molecular chain at the terminal portion during the polymerization process itself, rather than performing depolymerization after polymerization. This preliminary action achieves the desired reactivity while maintaining precise control over molecular weight within the prescribed range.
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 curing agents, achieves high molecular weight, and maintains good storage stability, enabling effective use in water dispersions for applications like paints and adhesives.
Implementation Method 1
a copolymerized polyester resin (A) having an unsaturated polyvalent carboxylic acid added to a side chain thereof, and the copolymerized polyester resin (A) contains, as copolymerization components
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).