Epoxy Organopolysiloxane UV Curing Hardness Trade-off
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Solution Overview
Problem
Epoxy group-containing organopolysiloxanes with high epoxy equivalent tend to compromise ultraviolet curability and organopolysiloxane characteristics, requiring higher epoxy content to improve UV curability, which decreases the relative amount of organopolysiloxane and lowers film hardness.
Innovation Solution
An epoxy group-containing organopolysiloxane with an epoxy equivalent of 500 g/mol or more, composed of specific monovalent hydrocarbon groups and a backbone of SiO4/2 units, combined with an onium salt photoinitiator, allowing for UV curability even with low epoxy content, resulting in a transparent and hard cured film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the content of epoxy group is increased to improve ultraviolet curability, then the ultraviolet curability is improved, but the relative amount of organopolysiloxane moiety decreases and the characteristic effect of organopolysiloxane is lowered
Solution Approach 1:
The invention changes the chemical structure parameters of the organopolysiloxane by introducing specific structural units (divalent arogenic hydrocarbon groups and epoxy groups at terminal positions) to achieve optimal balance between UV curability and organopolysiloxane characteristics. This structural parameter optimization allows the material to maintain high organopolysiloxane content while achieving sufficient epoxy group reactivity for UV curing.
Solution Approach 2:
The invention creates a composite structure within the organopolysiloxane molecule by combining siloxane backbone units with arogenic hydrocarbon groups and terminal epoxy groups. This composite molecular structure enables the material to exhibit both the characteristic properties of organopolysiloxane and the UV curability required for coating applications.
2Reliability
If the content of epoxy group is increased to improve ultraviolet curability, then the ultraviolet curability is improved, but the film hardness tends to decrease
Solution Approach 1:
The invention optimizes the epoxy group content parameter within a specific range (0.01 to 0.1 mmol/g) to achieve the desired balance between UV curability and film hardness. This controlled parameter adjustment ensures sufficient epoxy groups for UV curing while maintaining adequate crosslinking density for film hardness.
3Quantity of substance
If the epoxy equivalent is large (low epoxy group content) to maintain organopolysiloxane characteristics, then the characteristic effect of organopolysiloxane is maintained, but the ultraviolet curability decreases
Solution Approach 1:
The invention applies local quality by concentrating epoxy groups at the terminal positions of the organopolysiloxane chains rather than distributing them throughout the structure. This localized placement of reactive groups at the ends of molecules provides sufficient UV curability while preserving the bulk organopolysiloxane characteristics and properties.
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 UV curability and high hardness of the cured film, maintaining transparency and ease of handling, while being usable as a coating material for various base materials.
Implementation Method 1
an onium salt photoinitiator, allowing for UV curability even with low epoxy content
Data Source
AI summary
An epoxy group-containing organopolysiloxane shows the following average composition formula (1) and has an epoxy equivalent of 500 g/mol or more. The epoxy group-containing organopolysiloxane has excellent ultraviolet curability even when the content of epoxy group is small (when the epoxy equivalent is large), an ultraviolet curable silicone composition uses the same, and a method forms a cured film.In the formula, each R1 represents the same or different unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms (except for a group containing an epoxy group); R2 represents a group containing an epoxy group; R3 represents a hydrogen atom or a saturated monovalent hydrocarbon group having 1 to 4 carbon atoms; “a”, “b”, and “c” are positive numbers, “d” is 0 or a positive number, satisfying (a+b)/(c+d)=0.5 to 1.0.