Photocurable Composition Transparency Curability Trade-off
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Solution Overview
Problem
Conventional photocurable compositions used in stereolithography struggle to balance high curability with transparency and mechanical properties, such as glass transition temperature and hardness, when forming three-dimensional objects by stacking layers, as they often compromise on either transparency or mechanical strength due to the use of high concentrations of polymerization initiators which can cause coloring.
Innovation Solution
A photocurable composition comprising a monofunctional monomer with a polycyclic aliphatic group, a polyfunctional monomer, an alcohol, and an acylphosphine oxide photopolymerization initiator is used, where the acylphosphine oxide initiator provides photobleaching functionality to enhance transparency and curability, while the monomers improve glass transition temperature and hardness, and the alcohol further enhances transparency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high concentrations of polymerization initiators are used to improve curability, then curability is improved, but transparency deteriorates due to coloring
Solution Approach 1:
The patent changes the chemical structure parameters of the photopolymerization initiator from conventional types to acylphosphine oxide type, which has different photophysical properties. This parameter change allows the initiator to undergo photobleaching after polymerization, removing the coloring effect while maintaining high curability through efficient radical generation
Solution Approach 2:
The patent converts the harmful coloring effect of the photopolymerization initiator into a beneficial photobleaching effect. The acylphosphine oxide initiator absorbs light during polymerization (harmful coloring) but then undergoes photodecomposition to become transparent (beneficial), effectively converting the harmful optical absorption into a useful transparency enhancement after curing
2Ease of manufacture
If conventional photocurable compositions are used, then manufacturing process is simple, but mechanical properties (glass transition temperature and hardness) are insufficient
Solution Approach 1:
The patent creates a composite photocurable composition by combining multiple components with specific functions: acylphosphine oxide photopolymerization initiator for curability and transparency, polycyclic aliphatic group-containing monomer for mechanical strength and glass transition temperature, and alcohol for additional transparency enhancement. This composite approach achieves superior mechanical properties while maintaining ease of manufacture
Solution Approach 2:
The patent assigns different functional qualities to different components: the acylphosphine oxide initiator provides curability and transparency, the polycyclic aliphatic monomer provides mechanical strength and thermal properties (glass transition temperature), and the alcohol provides transparency enhancement. Each component contributes its specific local quality to the overall composition, achieving balanced performance
3Object-affected harmful factors
If transparency is prioritized by using low initiator concentration, then transparency is improved, but curability deteriorates
Solution Approach 1:
The patent changes the initiator efficiency parameter by selecting acylphosphine oxide type initiators, which have high quantum efficiency for radical generation. This allows achieving complete polymerization (high curability) at lower initiator concentrations, thereby maintaining transparency. The photobleaching property further enhances transparency after curing
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 composition achieves a three-dimensional object with excellent transparency, high glass transition temperature, and hardness, suitable for optical applications, by effectively balancing curability and transparency through the specific combination of monomers and initiator, allowing for the formation of objects with internal transmittance above 85% and Shore D hardness of at least 60.
Implementation Method 1
a photocurable composition containing a monofunctional monomer having a polycyclic aliphatic group, a polyfunctional monomer, an alcohol, and an acylphosphine oxide photopolymerization initiator
Implementation Method 2
the acylphosphine oxide initiator provides photobleaching functionality to enhance transparency and curability
Data Source
AI summary
A photocurable composition which can be used to manufacture a three-dimensional object that is formed by stacking a plurality of layers on top of each other, from which the three-dimensional object having excellent transparency, a high glass transition temperature, and a high hardness can be formed, and which exhibits a high curing rate. The photocurable composition is a photocurable composition used to manufacture a three-dimensional object that is formed by stacking a plurality of layers on top of each other. The photocurable composition contains a monofunctional monomer having a polycyclic aliphatic group, a polyfunctional monomer, an alcohol, and an acylphosphine oxide photopolymerization initiator.