Polyester Polyol Ambient Curing Low VOC Coatings
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Solution Overview
Problem
Existing coating compositions require high temperatures for curing, have high Volatile Organic Content (VOC), and compromise on durability due to unsaturated fatty acid esters, which impairs their oxidative crosslinking mechanism.
Innovation Solution
Development of a coating composition using polyester polyols prepared from a specific ratio of polyols, polycarboxylic acids, and saturated C6-C20 monobasic fatty acids, allowing for ambient temperature curing, high solid content, and low VOC, resulting in superior durability and quick curing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If polyester polyols are prepared from unsaturated fatty acid esters to enable oxidative crosslinking, then the coating composition can air-dry, but the durability of the coating is impaired
Solution Approach 1:
The invention changes the chemical composition parameters by using saturated and substantially saturated fatty acids instead of unsaturated fatty acid esters, while maintaining air-drying capability through alternative formulations that achieve durability without compromising oxidative crosslinking
Solution Approach 2:
The invention creates a composite coating system combining polyester polyol from saturated fatty acids with specific curing agents and additives that work together to provide both air-drying capability and enhanced durability, replacing the single-component unsaturated system
2Object-generated harmful factors
If coating compositions are formulated with high solid content to reduce VOC, then environmental performance improves, but curing requires high temperatures
Solution Approach 1:
The invention changes the chemical structure parameters of the polyester polyol by using specific saturated fatty acid chains and controlling molecular weight distribution, which reduces viscosity and enables ambient temperature curing while maintaining high solid content
Solution Approach 2:
The invention replaces thermal energy input (high temperature curing) with chemical reaction mechanisms that proceed at ambient temperatures, using the inherent reactivity of the polyester polyol with curing agents to achieve crosslinking without external heat
3Ease of manufacture
If polyester polyols with high hydroxyl value (200-400 mg KOH/g) are used to achieve proper coating formulation, then coating composition can be made, but the durability is inferior compared to lower hydroxyl value polyols
Solution Approach 1:
The invention optimizes the hydroxyl value parameter to a specific range (50-200 mg KOH/g) by controlling the ratio of polyol to polycarboxylic acid and selecting specific fatty acid chain lengths, achieving both formulation feasibility and superior durability
Solution Approach 2:
The invention creates local optimization in the molecular structure by using specific saturated fatty acid chains (C6-C20) that provide appropriate hydroxyl functionality distribution, resulting in localized regions of optimal crosslinking density that enhance overall coating durability
4Strength
If blocked polyisocyanate or aminoplast curing agents are used in high solids coating systems, then crosslinking can be achieved, but heat is required for curing
Solution Approach 1:
The invention extracts the blocking groups from the curing agent system, using unblocked polyisocyanates or alternative curing agents that react directly with the polyester polyol at ambient temperatures, eliminating the need for thermal activation
Solution Approach 2:
The invention introduces catalysts or promoter substances that mediate the reaction between polyester polyol and curing agents, enabling the crosslinking reaction to proceed at ambient temperatures by lowering the activation energy barrier
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 coating composition cures rapidly at ambient temperatures, achieves high solid content with low VOC, and exhibits excellent durability, outperforming previous compositions in terms of film formation and resistance to UV weathering.
Implementation Method 1
The coating compositions are capable of being cured at ambient temperature
Implementation Method 2
high solids/low VOC coating compositions
Data Source
AI summary
A coating composition having a solids content of greater than 70% by weight and/or a Volatile Organic Content (VOC) of less than 250 g/l, comprising a novel polyester polyol and a curing agent, wherein the coating composition is capable of curing at ambient temperature, and which provides a coating having excellent durability.