Dual-Cure Inkjet Ink Composition for Complete Silicone Curing
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Solution Overview
Problem
Existing inkjet inks based on acrylic-modified polysiloxanes face challenges with radical curing being instantaneous and incomplete without post-curing, and are hindered by oxygen during curing, limiting their applicability and effectiveness.
Innovation Solution
A curable composition comprising (meth)acryl-functional organohydrogenpolysiloxane with hydrosilyl groups, a photopolymerization initiator, and a hydrosilylation catalyst, with specific surface tension and viscosity, enabling both radical and addition curing, thus improving inkjet jettability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If acrylic-modified polysiloxane is used to increase surface tension for good inkjet jettability, then inkjet jettability is improved, but radical curing becomes instantaneous and incomplete without post-curing
Solution Approach 1:
The curing process is segmented into two distinct stages: instantaneous radical polymerization upon UV irradiation for initial setting, followed by gradual addition curing via hydrosilylation for complete crosslinking. This segmentation allows the ink to achieve both immediate handling properties and final structural integrity.
Solution Approach 2:
The composition is pre-formulated with both photopolymerization initiator and hydrosilylation catalyst, along with reactive functional groups, so that the dual-curing system is ready to execute in sequence upon UV exposure, eliminating the need for separate formulation adjustments.
2Productivity
If photopolymerization initiator is added for radical curing, then curing speed is improved, but oxygen present during curing hinders the reaction
Solution Approach 1:
The vinyl-containing organopolysiloxane acts as an intermediary that participates in both radical polymerization and hydrosilylation reactions, bridging the two curing mechanisms and allowing the system to overcome oxygen inhibition through the alternative addition curing pathway.
Solution Approach 2:
The composition combines multiple reactive components (acrylic-functional polysiloxane, vinyl-containing polysiloxane, photopolymerization initiator, and hydrosilylation catalyst) into a composite curable system that leverages both radical and addition mechanisms to achieve complete curing despite oxygen presence.
3Ease of operation
If long-chain alkyl groups are substituted on silicon atoms to increase surface tension, then inkjet jettability is improved, but molecular weight and viscosity increase
Solution Approach 1:
The invention optimizes the physical parameters of the polysiloxane by controlling the degree of substitution with long-chain alkyl groups, balancing surface tension enhancement for inkjet deposition against viscosity increase that would hinder jetting performance.
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 stable inkjet jettability and allows for both radical and addition curing, making it suitable for applications like coatings, sealants, adhesives, and stereolithography materials.
Implementation Method 1
When an acrylic-modified polysiloxane is mixed with a photoinitiator and irradiated with ultraviolet light, the photoinitiator cleaves, forming active radicals
Implementation Method 2
addition curable via hydrosilylation
Data Source
AI summary
A curable composition which comprises (A) an organopolysiloxane represented by formula (1) (wherein R1 represents an alkyl group, R2 represents an alkyl or aryl group, R3 represents a hydrogen atom or methyl group, Me represents a methyl group, m is an integer of 1-10, and a and b are integers of 1 or larger, a+b being an integer of 3-120), (B) a photopolymerization initiator, and (C) a hydrosilylation catalyst and which has a surface tension at 23°C of 23-30 mN/m and a viscosity at 23°C of 5-80 mPa·s.