Hydroxy Polyester Resins for Dye Ink Sublimation
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Solution Overview
Problem
Current transfer printing methods face challenges in achieving substrates with good mechanical properties, complete image transfer, easy image support detachment, and environmental sustainability, particularly due to the use of toxic isocyanate-functional curing agents and inadequate resin properties.
Innovation Solution
A thermally curable powder coating composition is developed, blending hydroxy functional polyester resins with high and low hydroxyl values, cured with self-blocked uretdione, which provides optimal glass transition temperature and hardness for detailed and durable decorations with excellent weather resistance, using renewable resources and petrochemical-based monomers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If isocyanate-functional curing agents are used, then curing performance is improved, but environmental safety deteriorates due to toxicological aspects
Solution Approach 1:
The patent extracts and removes the harmful isocyanate functional groups from the curing agent system, replacing them with self-blocked uretdione which decomposes to release CO2 and forms isocyanate groups in situ only during curing, eliminating the need for storing and handling toxic isocyanates while maintaining curing performance
Solution Approach 2:
The patent introduces self-blocked uretdione as an intermediary substance that serves as a safe storage form of isocyanate groups. This intermediary decomposes under curing conditions to provide the necessary isocyanate functionality for crosslinking, acting as a mediator between safety requirements and curing performance needs
2Reliability
If resin with high hydroxyl value is used, then crosslinking density is improved, but viscosity increases making application difficult
Solution Approach 1:
The patent segments the hydroxyl functionality by using a mixture of polyester resins with different hydroxyl values (one with high hydroxyl value for crosslinking density and another with lower hydroxyl value for viscosity control), allowing each component to fulfill its specific function without the drawbacks of the other
Solution Approach 2:
The patent changes the parameter distribution of hydroxyl groups by combining resins with different hydroxyl values rather than using a single resin type, optimizing the balance between crosslinking density and viscosity through parameter diversification
3Manufacturing precision
If glass transition temperature is increased for better transfer printing, then image transfer quality is improved, but coating becomes too brittle causing substrate damage
Solution Approach 1:
The patent optimizes the glass transition temperature parameter to a specific range (60-90°C) that balances image transfer quality and coating flexibility, avoiding both too low (poor transfer) and too high (brittleness) extremes through precise parameter control
4Manufacturing precision
If detailed decorations are achieved with complete image transfer, then manufacturing precision is improved, but process complexity increases
Solution Approach 1:
The patent employs self-blocked uretdione that automatically decomposes and releases isocyanate groups during the curing process, providing self-regulated crosslinking without requiring complex external control systems, thereby achieving high precision with simplified process control
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 solution enables detailed and durable decorations with bright colors, ensuring complete image transfer, easy image support detachment, and improved outdoor resistance, while being environmentally friendly and suitable for heat-sensitive substrates, with optimal performance between 170°C to 220°C.
Implementation Method 1
cured with a self blocked uretdione
Implementation Method 2
hydroxy functional polyester resins with a high hydroxyl value between 200-350 mgKOH/g and a hydroxy functional polyester resin with a low hydroxyl value
Implementation Method 3
thermally curable powder coating composition
Data Source
AI summary
The present invention relates to a thermally curable powder coating composition based on hydroxy functional polyester resins with a high hydroxyl value blended with a low hydroxyl value resin and both cured with a self blocked uretdione, and its use in the preparation of a decorated substrate, by transfer printing. The transfer printing comprises the steps of : submitting a substrate to a treatment to prepare its surface for the application of a coating, applying a coating to the surface of the substrate in one or more cycles, covering the surface of the substrate with a sheet comprising a decoration which is to be transferred to said surface, and heating the substrate and the sheet comprising the decoration to effect the transfer of the decoration from the sheet onto the substrate.