Aqueous Emulsion Binder for Inkjet Adhesiveness and Redispersibility
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Solution Overview
Problem
Conventional aqueous pigment-based inkjet inks face challenges with high viscosity, poor redispersibility, and adhesiveness to various substrates, particularly films, due to the limitations of existing binders, which affect printability and storage stability.
Innovation Solution
An aqueous emulsion solution comprising an A-B block copolymer, where one polymer block is water-insoluble and the other is neutralized with an alkali, mixed with a hydrophobic addition polymerizable monomer, forming a stable emulsion that reduces viscosity and enhances adhesiveness and redispersibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If water-soluble polymers are used as binders to improve redissolvability, then the ink can be redissolved in water-based media, but the viscosity of the ink becomes high and ejection stability deteriorates
Solution Approach 1:
The invention changes the chemical structure parameters of the polymer by introducing specific functional groups (carboxyl groups with controlled content) and using copolymerization to achieve the desired balance between water solubility and viscosity control
Solution Approach 2:
The invention uses composite polymer structures combining hydrophilic and hydrophobic segments, and copolymerizing different monomers to create a binder that simultaneously provides redissolvability and maintains low viscosity for good ejection stability
2Reliability
If the concentration of carboxy groups in the polymer is increased to improve water solubility and redissolvability, then the ink redissolvability improves, but the viscosity becomes high and water fastness deteriorates
Solution Approach 1:
The invention precisely controls the carboxyl group content within the range of 0.1-10 mmol/g, and uses copolymerization to balance water solubility with water fastness by incorporating hydrophobic monomers
Solution Approach 2:
The invention creates local hydrophobic and hydrophilic regions within the polymer structure through copolymerization, allowing different parts of the polymer to contribute differently to water solubility and water fastness
3Strength
If high molecular weight polymers are used to improve adhesiveness to substrates, then the adhesiveness improves, but the ink viscosity increases and redissolvability deteriorates
Solution Approach 1:
The invention optimizes the molecular weight parameters of the polymer within specific ranges and uses copolymerization to maintain adhesiveness while improving redissolvability through controlled chemical structure
Solution Approach 2:
The invention uses composite polymer structures with both high molecular weight segments for adhesiveness and hydrophilic segments for redissolvability, achieving a balance between these conflicting properties
4Stability of the object's composition
If conventional binders are used to form coating films, then the coating film can be formed, but the adhesiveness to various films and paper quality is insufficient
Solution Approach 1:
The invention designs a polymer binder with multiple functional groups and copolymer structures that can interact with different substrate types (paper, films), providing universal adhesiveness across various substrates
Solution Approach 2:
The invention uses composite polymer structures combining different monomer units with complementary properties, enabling the binder to adhere to diverse substrates while maintaining coating film stability
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 improves inkjet printability, ejection stability, and storage stability by maintaining low viscosity and ensuring excellent adhesiveness to substrates, while allowing for easy redispersion of dried ink, thus addressing the limitations of conventional binders.
Implementation Method 1
an aqueous emulsion solution comprising a polymer I and a polymer II mixed together therein
Implementation Method 2
a polymer block B is synthesized using, as a polymer block-forming component, a monomer comprising at least a methacrylic acid and has an acid value of 30 to 250 mgKOH/g
Data Source
Figure 1
AI summary
A novel aqueous emulsion solution is provided that can be used as a binder for forming a coating film suitable for an inkjet printing system. The present invention is an aqueous emulsion solution containing a polymer I and a polymer II mixed together therein, wherein the polymer I is an A-B block copolymer formed from 90 mass% or more of a methacrylate-based monomer, the A-B block copolymer neutralized with an alkali, a polymer block A is substantially water-insoluble and has a number average molecular weight of 1000 to 10000 and a polydispersity index of 1.5 or less, a polymer block B is synthesized using a monomer containing at least a methacrylic acid and has an acid value of 30 to 250 mgKOH/g, the A-B block copolymer has a number average molecular weight of 5000 to 20000, a content of the polymer block A of 5 to 60 % in the A-B block copolymer, and a polydispersity index as a whole of 1.6 or less, the polymer II is a polymer obtained by polymerizing a hydrophobic addition polymerizable monomer and having a glass transition temperature of 70°C or lower, and further the mass ratio of the polymer I and the polymer II is 5 to 80:95 to 20.