Photocurable Silicone Composition Deep Curing and Haze Resistance
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Solution Overview
Problem
Existing ultraviolet radiation-curable silicone compositions face issues with poor deep curability and the occurrence of coloring and haze when exposed to high temperature or high humidity conditions.
Innovation Solution
A photocurable silicone composition comprising an organopolysiloxane with specific molecular formula, an organic compound with ether bonds and aliphatic carbon-carbon double bonds, a compound with thiol groups, a photoradical initiator, and a hindered phenol compound, which is irradiated with active energy rays to achieve deep curability and maintain transparency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ultraviolet radiation-curable silicone composition is used, then the composition can be cured by ultraviolet radiation, but the deep curability is poor and insufficient curing occurs
Solution Approach 1:
The patent changes the chemical composition parameters by introducing a specific organopolysiloxane with controlled molecular structure (formula Vi,aMe2SiO(MePhSiO)bSiMe2Vi where 1≤a+b≤2.5 and 0.001≤a/(a+b)≤0.2) and controlling the ratio of aromatic/aralkyl groups (at least 30 mol %). This parameter optimization enables deep curing by adjusting the polymer's optical and chemical properties to better absorb and utilize UV radiation throughout the material depth.
Solution Approach 2:
The patent creates a composite curing system combining multiple components: the specialized organopolysiloxane (A), ether-containing organic compound (B), thiol group compound (C), phosphorus-containing photoradical initiator (D), and hindered phenol compound (E). This composite formulation synergistically improves deep curability through combined chemical reactions initiated by UV radiation.
2Reliability
If conventional silicone composition is used, then the composition can be cured, but coloring and haze occur when exposed to high temperature or high humidity conditions
Solution Approach 1:
The patent incorporates hindered phenol compound (E) as a stabilizer that converts the harmful effect of UV radiation and environmental factors into a beneficial stabilization mechanism. The hindered phenol acts as a radical scavenger and antioxidant, preventing photo-oxidation and thermal degradation that cause coloring and haze, thereby transforming potential degradation pathways into protective effects.
Solution Approach 2:
The patent modifies the chemical composition by controlling the molecular structure parameters of the organopolysiloxane (specific ratios of a and b in the formula) and the content of functional groups, which changes the material's resistance to environmental factors like heat and humidity, preventing coloring and haze while maintaining transparency.
3Reliability
If the composition is designed for deep curability, then curing penetrates deeper, but the formulation becomes more complex
Solution Approach 1:
The patent designs each component to serve multiple functions: the organopolysiloxane (A) provides both the base polymer structure and UV absorption; the ether-containing compound (B) acts as both a reactive monomer and a plasticizer; the thiol group compound (C) serves as a curing agent and viscosity controller; the phosphorus initiator (D) provides both initiation and some stabilization; the hindered phenol (E) acts as both a stabilizer and a radical scavenger. This multi-functionality reduces the need for additional separate components, simplifying the overall formulation while achieving deep curability.
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 excellent deep curability and maintains transparency without causing haze, even under high temperature/high humidity conditions, resulting in a cured product with improved mechanical strength and heat resistance.
Implementation Method 1
a photocurable silicone composition comprising: (A) 100 parts by mass of an organopolysiloxane represented by the average composition formula: R1aR2bSiO(4-a-b)/2 wherein, R1 is an alkenyl group having from 2 to 12 carbons... (D) from 0.05 to 1.0 part by mass of a photoradical initiator having a phosphorus atom
Implementation Method 2
a compound having at least two thiol groups in a molecule, in an amount that the amount of the thiol groups in the present component is from 0.2 to 2.0 mol per 1 mol of the total aliphatic carbon-carbon double bonds in the present composition
Data Source
AI summary
A photocurable silicone composition comprises: (A) an organopolysiloxane represented by the average composition formula: R1aR2bSiO(4-a-b)/2 where R1 is an alkenyl group having from 2 to 12 carbons, R2 is an alkyl group having from 1 to 12 carbons, an aryl group having from 6 to 12 carbons, or an aralkyl group having from 7 to 12 carbons; provided that, at least 30 mol % of R2 are the aryl groups or the aralkyl groups; and “a” and “b” are positive numbers satisfying: 1≤(a+b)≤2.5 and 0.001≤a/(a+b)≤0.2; (B) an organic compound having at least two ether bonds and at least one aliphatic carbon-carbon double bond in a molecule; (C) a compound having at least two thiol groups in a molecule; (D) a photoradical initiator having a phosphorus atom; and (E) a hindered phenol compound.