Curable Inkjet Ink Composition With Dual Curing and Stable Jetting
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Solution Overview
Problem
Existing inkjet compositions, particularly those containing polydimethylsiloxanes, suffer from low surface tension and poor inkjet jettability, and radical curing is hindered by short-lived radicals and oxygen inhibition, limiting their applicability in coating and adhesive applications.
Innovation Solution
A curable composition comprising (meth)acryl-functional organohydrogenpolysiloxane with hydrosilyl groups, a photopolymerization initiator, and a hydrosilylation catalyst, achieving a surface tension of 23 to 30 mN/m and viscosity of 5 to 80 mPa·s, enabling both radical and addition curing through (meth)acryloyl groups and hydrosilylation reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If polydimethylsiloxanes are used in inkjet composition, then the composition has low surface tension, but inkjet jettability deteriorates
Solution Approach 1:
The patent uses a composite material system combining polydimethylsiloxane base resin with acrylic-modified polysiloxane additives. This composite approach allows the main resin to provide low surface tension while the modified polysiloxane component improves inkjet jettability by adjusting surface properties and flow characteristics, thus resolving the contradiction between low surface tension and good jetting performance
Solution Approach 2:
The patent modifies physical parameters of the polysiloxane system by introducing acrylic modification with long-chain alkyl groups. This chemical modification changes the surface tension characteristics and viscosity parameters, enabling the material to achieve both low surface tension for good substrate wetting and appropriate viscosity for successful inkjet droplet ejection
2Speed
If radical polymerization is used for curing, then curing proceeds instantaneously with UV irradiation, but postcure by heating becomes impossible due to short-lived radicals
Solution Approach 1:
The patent segments the curing process into two distinct stages: first, rapid radical polymerization under UV irradiation for immediate curing; second, thermal postcure treatment to complete the curing process. This segmentation allows each curing mechanism to perform its optimal function - UV for speed and thermal treatment for completeness - resolving the contradiction between instantaneous curing and postcure capability
Solution Approach 2:
The patent ensures continuous curing action by combining two curing mechanisms that operate at different stages. The radical polymerization provides initial rapid curing, and the subsequent thermal treatment continues the curing process to achieve complete crosslinking. This continuous action across different time scales and mechanisms resolves the limitation of short-lived radicals by extending the curing timeline with a second phase
3Reliability
If oxygen is present during curing, then oxygen inhibition occurs, but complete curing cannot be achieved
Solution Approach 1:
The patent employs an inert atmosphere approach by conducting the thermal postcure treatment in a controlled environment that minimizes oxygen exposure. This creates an oxygen-deficient condition during the critical curing phase, preventing oxygen inhibition and allowing complete crosslinking to proceed, thus resolving the contradiction between curing completeness and oxygen inhibition
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 exhibits good inkjet jettability and curability, suitable for coatings, sealants, adhesives, and stereolithography materials, allowing for stable jetting and effective curing on various substrates.
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
a curable composition which contains a (meth)acryl-functional organohydrogenpolysiloxane having hydrosilyl groups and alkyl groups on the molecule, a photopolymerization initiator and a hydrosilylation catalyst and which possesses a given surface tension and a given viscosity has a good inkjet jettability and also is both radical-curable via the (meth)acryloyl groups and 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.