Unsaturated Polyester Prepolymer Free Radical Polymerization
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Solution Overview
Problem
Conventional polyester resins used in coatings have limitations due to low molecular weight and functionality, leading to poor substrate adhesion, compatibility issues, and an inability to achieve the required balance of chemical resistance and flexibility, especially in extreme stress conditions like those encountered in packaging and coil coating industries.
Innovation Solution
A crosslinkable polyester is prepared through free radical polymerization of unsaturated polyester prepolymers with a controlled number average functionality of 0.05 to 25, allowing for higher molecular weight and functionality while maintaining reactivity with crosslinkers, thereby enhancing adhesion and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the functionality of polyester is increased to improve adhesion and durability, then the molecular weight decreases, resulting in poor substrate adhesion and limited compatibility
Solution Approach 1:
The patent segments the polyester structure into distinct functional units: polyol chains providing molecular weight and flexibility, and polyacid units providing functionality. This segmentation allows each component to contribute its optimal properties without compromising the other, resolving the contradiction between high functionality and high molecular weight
Solution Approach 2:
The patent creates a composite polyester structure combining polyol and polyacid components with specific functionality ranges. The polyol portion (0.5-2.0 equivalents) provides molecular weight backbone while the polyacid portion (0.1-0.5 equivalents) provides crosslinking functionality, achieving both high molecular weight and high functionality simultaneously
2Stability of the object's composition
If conventional polyester resins are used to achieve flexibility, then chemical resistance and resistance to mechanical deformation are insufficient under extreme stress conditions
Solution Approach 1:
The patent changes the chemical parameters of the polyester by controlling the equivalence ratios of polyol and polyacid, and selecting specific functional groups. This parameter optimization allows the resin to achieve both flexibility (through polyol chain mobility) and chemical resistance (through dense crosslinking network from high functionality polyacid units)
Solution Approach 2:
The patent creates a composite network combining flexible polyol segments with highly crosslinkable polyacid segments. The polyol chains maintain flexibility and chain mobility while the high functionality polyacid units (0.1-0.5 equivalents) create a dense crosslinking network that provides chemical resistance and mechanical strength, resolving the contradiction between flexibility and durability
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 polyesters exhibit improved molecular weight and functionality, leading to enhanced adhesion, durability, and flexibility, as well as improved resistance to mechanical deformation and sterilization, making them suitable for demanding applications such as packaging and coil coatings.
Implementation Method 1
crosslinkable polyesters prepared by free radical polymerization of the double bonds of an unsaturated polyester prepolymer
Data Source
AI summary
A polyester prepared by free radical polymerization of an unsaturated polyester prepolymer, wherein the polymerization occurs primarily by reaction of the unsaturation of said prepolymer is disclosed. Coatings comprising the same are also disclosed, as are substrates coated at least in part with such coating.