Copolymerized Saturated Polyester Coating Resin for Hydrolysis Resistance
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Solution Overview
Problem
Existing polyester resins suffer from deterioration in physical properties due to hydrolysis by water or aqueous solutions, particularly at high temperatures, compromising corrosion resistance and chemical resistance, while also facing challenges in solubility and processability.
Innovation Solution
A copolymerized saturated polyester resin is developed with a specific composition and structural design, including a glass transition temperature of 60 to 120°C, intrinsic viscosity of 0.4 to 0.7 dl/g, and number average molecular weight of 12,000 to 20,000 g/mol, using aromatic dicarboxylic acids, alicyclic and aliphatic polyhydric alcohols, and trifunctional carboxylic acids to enhance corrosion and chemical resistance, solubility, and processability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If high molecular weight saturated polyester resin is used to improve processability, then processability is improved, but corrosion resistance deteriorates due to hydrolysis by water or aqueous solutions
Solution Approach 1:
The patent applies parameter changes by precisely controlling the glass transition temperature (60-120°C), intrinsic viscosity (0.4-0.7 dl/g), and number average molecular weight (12,000-20,000 g/mol) of the polyester resin. These parameter optimizations resolve the contradiction by achieving a balance where the resin maintains sufficient molecular weight for processability while controlling physical properties to resist hydrolysis and improve corrosion resistance.
Solution Approach 2:
The patent creates a composite resin system by copolymerizing multiple monomers including aromatic dicarboxylic acids, alicyclic polyhydric alcohols, and aliphatic polyhydric alcohols with specific side chains. This composite approach combines the benefits of different monomer structures to achieve both good processability and enhanced corrosion resistance that single-component resins cannot provide.
2Reliability
If resin structure is modified to enhance corrosion resistance and chemical resistance, then corrosion resistance is improved, but solubility in solvent deteriorates
Solution Approach 1:
The patent resolves this contradiction through parameter changes by controlling the glass transition temperature within 60-120°C and intrinsic viscosity within 0.4-0.7 dl/g. These parameter ranges optimize the balance between corrosion resistance and solubility, allowing the resin to maintain adequate solubility in solvents while achieving the required corrosion resistance through controlled physical properties.
3Reliability
If high glass transition temperature is used to suppress fluidity at high temperatures, then corrosion resistance is improved, but processability deteriorates
Solution Approach 1:
The patent applies parameter changes by optimizing the glass transition temperature to a specific range (60-120°C) rather than maximizing it. This controlled parameter change suppresses excessive fluidity at high temperatures to improve corrosion resistance while maintaining sufficient processability that would be lost at excessively high glass transition temperatures.
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 copolymerized resin achieves excellent corrosion and chemical resistance, good solubility in solvents, and processability, making it suitable for coating metal substrates, especially pre-coated metals and can surfaces.
Implementation Method 1
the phenomenon in which the properties of a coating film formed from a polyester resin are deteriorated by water or an acidic or alkaline aqueous solution is known to be mainly caused by hydrolysis of the polyester resin by moisture penetrating and diffusing into the coating film
Implementation Method 2
it is necessary that a binder resin and a curing agent component are chemically bonded to have a high curing density, so that moisture hardly penetrates and diffuses into a coating film
Implementation Method 3
the corrosion resistance and chemical resistance are remarkably improved by controlling the glass transition temperature of a resin to thereby suppress the fluidity of a coating film at high temperatures
Implementation Method 4
the solubility of a polyester resin in a solvent and the processability of a coating film can be improved even at a high glass transition temperature by controlling the constituent components of the resin
Data Source
Figure 1
AI summary
The present invention relates to a copolymerized saturated polyester resin and a coating composition containing same. Provided are a copolymerized saturated polyester resin and a coating composition having excellent corrosion resistance and chemical resistance when formed into a coating film, showing excellent processability and resin solubility, and thus particularly useful for coating a can and pre-coated metal