Branched Polyester Polyol Plasticizer for Coatings
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Solution Overview
Problem
Conventional plasticizers, such as phthalates, pose health hazards and environmental concerns, and existing alternatives like aliphatic polyesters can cause sticky surfaces and suboptimal film properties, while also being volatile and non-compliant with VOC regulations.
Innovation Solution
A coating composition incorporating a branched polyester polyol, synthesized by reacting a polyol with an aliphatic dicarboxylic acid, a cyclic carboxylic acid anhydride, and an epoxide-functional compound, which acts as a non-volatile, hazard-free plasticizer at low concentrations, maintaining film properties and adhering to VOC regulations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If phthalic esters are used as plasticizers, then the coating provides good elasticity and reduced film forming temperature, but the plasticizer migrates through the coating surface and evaporates, gradually decreasing plasticizing effect, and poses health hazards
Solution Approach 1:
The patent changes the molecular weight parameter of the plasticizer by using high molecular weight aliphatic polyester polyols (average molecular weight of 500-10,000) instead of low molecular weight phthalic esters. This parameter change prevents migration and evaporation while maintaining plasticizing effect, and eliminates health hazards associated with phthalates.
Solution Approach 2:
The patent creates a composite plasticizing system by combining aliphatic polyester polyols with film-forming resins in specific ratios (0.1-10% by weight). This composite approach integrates the plasticizing function directly into the coating matrix, preventing migration while maintaining elasticity and durability.
2Reliability
If aliphatic polyesters are used as plasticizers, then the coating provides long term effects and non-volatile properties, but the coating surface becomes sticky and other surface properties deteriorate
Solution Approach 1:
The patent optimizes the molecular weight parameter of the aliphatic polyester polyol (500-10,000) and controls the concentration parameter (0.1-10% by weight) to achieve the right balance. This parameter optimization maintains non-volatile, long-term stability while preventing surface stickiness and preserving adhesion properties.
3Reliability
If high concentrations of plasticizer are used to achieve desired elasticity, then the coating provides good flexibility, but the coating composition becomes complex and other film properties are compromised
Solution Approach 1:
The patent changes the concentration parameter by using very low amounts of plasticizer (0.1-10% by weight, preferably 0.5-5%). This low concentration approach achieves desired elasticity without compromising other film properties like adhesion, hardness, and surface finish, while simplifying the overall coating composition.
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 branched polyester polyol provides excellent durability and low volatile organic content, improving elasticity and adhering to VOC regulations without causing sticky surfaces or compromising adhesion, even at low concentrations.
Implementation Method 1
This can be achieved by having plasticizing carried out during the manufacture of the film forming resin by incorporation of elasticizing segments or monomers which sterically hinder such interaction
Implementation Method 2
When chain mobility of film forming resins is restricted by molecular interaction, for example by strong van-der-Waals' forces, the task of a plasticizer is to reduce or to entirely prevent the formation of such bridging forces
Data Source
AI summary
The present invention relates to a coating composition comprising (A) a physically curing, reactively self-curing and/or externally curing component, comprising based on the total solids content of (A), from 0.1 % by weight to about 2.5 % by weight of a branched polyester polyol, preparable by: (a) reacting a polyol comprising at least three hydroxyl groups with an aliphatic dicarboxylic acid having from 6 to 36 carbon atoms or an esterifiable derivative of the aliphatic dicarboxylic acid selected from their anhydrides and esterifiable esters to form a hydroxyl-functional first intermediate product; (b) reacting the first intermediate product with a cyclic carboxylic acid anhydride to form a carboxylic acid-functional second intermediate product; and (c) reacting the second intermediate product with an epoxide-functional compound having one epoxide group to form the branched polyester polyol; and (B) a crosslinking component in case (A) comprises one or more externally curing components; and optionally (C) a diluent component. The invention further relates to a method of coating a substrate, making use of the coating compositions and the use of the branched polyester polyols as defined above as plasticizers.