Bisacyl Digermanium Photoinitiators for Visible Light Curing
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Solution Overview
Problem
Current photoinitiators for visible light curing, such as camphorquinone, suffer from limitations like yellow discoloration and reduced transparency, and the synthesis of bisacyldialkyl germanium compounds is costly and inefficient.
Innovation Solution
Development of bisacyl digermanium compounds with specific reactivity and absorption characteristics for visible light curing, synthesized through a method involving dihalogeno tetraalkyl digermane reaction with dithiane compounds followed by dethioketalization, offering improved polymerization-initiating effects and through-curing depth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If camphorquinone is used as photoinitiator for visible light curing, then polymerization can be initiated, but yellow discoloration and reduced transparency occur
Solution Approach 1:
The patent changes the chemical structure parameters of the photoinitiator from camphorquinone to bisacyl digermanium compounds, which have different absorption characteristics and do not produce yellow discoloration upon curing, thus resolving the contradiction between polymerization initiation and color stability
Solution Approach 2:
The patent uses a composite photoinitiator system combining bisacyl digermanium compounds with specific coinitiators, creating a new material composition that achieves effective polymerization initiation without the harmful yellow discoloration effect of conventional camphorquinone systems
2Productivity
If UV curing is used for coatings, then high reaction rate is achieved, but transparency and through-curing depth are limited
Solution Approach 1:
The patent changes the wavelength parameter of the curing light from UV to visible light range (400-500 nm), and adjusts the photoinitiator structure to absorb visible light, enabling deeper penetration through pigmented and thicker materials while maintaining adequate curing speed
Solution Approach 2:
The patent creates a dynamic curing system that adapts to different material thicknesses and pigmentation levels by using visible light photoinitiators that can penetrate deeper into the material, allowing the curing process to effectively reach throughout the entire volume of the coating or dental material
3Quantity of substance
If conventional synthesis methods are used for bisacyldialkyl germanium compounds, then photoinitiators can be produced, but synthesis is costly and inefficient
Solution Approach 1:
The patent extracts and eliminates the costly and inefficient steps from the conventional synthesis route, using a streamlined method that directly produces bisacyl digermanium compounds without the need for expensive column chromatography purification, thereby reducing manufacturing cost and improving efficiency
Solution Approach 2:
The patent replaces expensive purification methods (column chromatography) with simpler, cheaper purification approaches, making the synthesis process more economically viable and suitable for large-scale production of photoinitiators
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 bisacyl digermanium compounds provide excellent polymerization-initiating effects and high through-curing depth with visible light, suitable for dental materials and other applications, overcoming the limitations of existing photoinitiators in terms of transparency and synthesis costs.
Implementation Method 1
Photoinitiators play a decisive role for the curing of photopolyreactive resins. Upon irradiation with UV or visible light it absorbs light and forms the polymerization-initiating species. In the event of radical polymerization these are free radicals.
Implementation Method 2
Norrish type I photoinitiators form free radicals upon irradiation by unimolecular bond cleavage.
Data Source
Figure 1
AI summary
The present invention discloses bisacyl digermanium compounds according to the general formula R1R2R3-Ge-Ge-R4R5R6, wherein each R1 and R4 is an acyl group, and the use of such compounds as initiators for radical polymerization.