Polyester Polyol Resin for Additive Manufacturing
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Solution Overview
Problem
Current additive manufacturing materials for lithography-based processes, such as stereolithography, lack sufficient mechanical properties like tensile strength and elongation at break, making them brittle and prone to water absorption.
Innovation Solution
A composition comprising the reaction product of a polyester polyol and a compound with acrylate- or methacrylate-functional groups, based on organic acids with two carboxyl groups and polyols with two hydroxy-groups, which can be processed at temperatures below 120°C and includes a photoinitiator, allowing for improved mechanical properties and reduced viscosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If crosslinking density is reduced or molecular weight of monomers is increased to improve mechanical properties (toughness and elongation at break), then mechanical properties are improved, but viscosity or melting point of uncured resins increases
Solution Approach 1:
The patent changes the chemical parameters of the resin system by using polyester polyols with specific molecular weights (500-5000 g/mol) and incorporating compounds with acrylate or methacrylate groups. This chemical parameter change allows achieving good mechanical properties (toughness and elongation) while keeping the melting point below 100°C and viscosity manageable, resolving the contradiction between mechanical property improvement and melting point increase.
2Strength
If crosslinking density is reduced or molecular weight of monomers is increased to improve mechanical properties (toughness and elongation at break), then mechanical properties are improved, but viscosity of uncured resins increases
Solution Approach 1:
The patent optimizes the molecular weight parameter of polyester polyols (500-5000 g/mol) and uses compounds with acrylate or methacrylate groups to achieve a balance where mechanical properties (toughness and elongation) are improved while viscosity remains below 20 Pa·s at room temperature, resolving the contradiction between mechanical property improvement and viscosity increase.
3Ease of manufacture
If conventional resins are used for lithography-based additive manufacturing, then processing is straightforward, but mechanical properties (tensile strength and elongation at break) are insufficient and products are brittle with high water absorption
Solution Approach 1:
The patent creates a composite resin system combining polyester polyols (providing mechanical strength and toughness) with compounds containing acrylate or methacrylate groups (providing photopolymerizability). This composite approach maintains ease of manufacturing through standard lithography-based additive manufacturing while achieving superior mechanical properties including tensile strength, elongation at break, and reduced brittleness.
4Ease of operation
If resins with higher viscosity (≥20 Pa·s) are processed by heating to at least 30°C, then highly viscous resins can be processed, but processing temperature increases
Solution Approach 1:
The patent changes the viscosity parameter of the resin by selecting polyester polyols with molecular weights of 500-5000 g/mol and using compounds with acrylate or methacrylate groups, achieving a resin system with viscosity below 20 Pa·s at room temperature. This eliminates the need for heating to process highly viscous resins, maintaining processing temperature below 100°C and resolving the contradiction between processability and temperature increase.
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 provides improved tensile strength and elongation at break, with the ability to process at lower temperatures and without solvents, resulting in materials with enhanced mechanical properties suitable for elastomeric products.
Implementation Method 1
radical (e.g. for acrylates) or cationic (e.g. for epoxides) polymerization is frequently used. For this purpose, special photoinitiators are added to the resin, which change their state by exposure and thus trigger the polymerization of the reactive components.
Data Source
AI summary
The present invention relates to an additive manufacturing process using a composition comprising the reaction product of a polyester polyol and a compound comprising at least one functional group that can react with a hydroxyl-group of the polyester polyol and at least one further functional group, selected from acrylate-or methacrylate-group, wherein the polyester polyol is based on at least one organic acid comprising at least two carboxyl groups or its anhydride and at least one polyol comprising at least two hydroxy-groups, wherein the reaction product has a glass transition temperature Tg of below 23° C., wherein the composition optionally further comprises a photoinitiator, as a photopolymerizable material in.