Acrylic Polymer Inkjet Ink for Higher Optical Density on Plain Paper
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Solution Overview
Problem
Existing pigment-based inkjet ink compositions face challenges in achieving suitable optical density on plain paper due to pigment penetration into the paper fiber network, leading to low optical density on the top surface and high see-through on the back side, and the use of paper treatments to prevent this adds cost.
Innovation Solution
Inkjet ink compositions comprising a pigment with an organic group covalently bonded and an acrylic polymer with specific molecular weight and acid number, partially neutralized with a base having a guanidine structure, enhance optical density by improving pigment retention on the paper surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If pigment is deposited on plain paper, then the ink composition achieves coloration, but pigment penetrates into the paper fiber network resulting in low optical density on the top surface
Solution Approach 1:
The patent introduces a binder resin as an intermediary substance between the pigment and the paper. The binder resin adheres to the pigment particles and holds them on the paper surface, preventing penetration into the fiber network. This mediator enables the pigment to maintain its position while still achieving coloration, thereby improving optical density without sacrificing pigment retention.
Solution Approach 2:
The invention creates a composite material system consisting of pigment particles bound with binder resin. This composite structure allows the pigment to be held together and attached to the paper surface through the binder's adhesive properties, preventing individual pigment particles from penetrating deep into the paper fibers and thus improving optical density.
2Illumination intensity
If paper treatment is applied to prevent pigment penetration, then optical density is improved, but manufacturing cost increases
Solution Approach 1:
The binder resin provides a self-service solution by inherently preventing pigment penetration through its adhesive properties. Instead of requiring external paper treatments to achieve pigment retention, the binder resin itself performs the function of holding pigment on the surface, thereby improving optical density without adding the cost of paper treatment processes.
Solution Approach 2:
The binder resin acts as an intermediary that eliminates the need for paper treatment. By providing adhesive binding between pigment and paper, it replaces the need for costly paper surface modifications, achieving the same optical density improvement through a different mechanism that does not require additional manufacturing steps.
3Speed
If ink formulation is adjusted to enable faster drying, then drying speed is improved, but optical density decreases due to insufficient time for pigment interaction
Solution Approach 1:
The binder resin serves as a mediator that enables simultaneous achievement of fast drying and high optical density. It provides immediate adhesive binding to hold pigment on the surface, allowing the ink to dry quickly without requiring extended interaction time between pigment and paper, thus maintaining both drying speed and optical density.
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 results in improved optical density and stability of the ink composition, balancing pigment retention and compatibility without significantly reducing optical density, even in low water environments.
Implementation Method 1
binds the pigment particles to the paper surface, thereby preventing the pigment particles from penetrating into the paper fiber network
Implementation Method 2
The di/trivalent metal ions coagulate with the pigments to form larger aggregates. The at least one organic group having a calcium index value greater than a calcium index value of 1,2,3-benzene tricarboxylic acid
Implementation Method 3
The di/trivalent metal ions coagulate with the pigments to form larger aggregates
Data Source
AI summary
Disclosed herein are inkjet ink compositions comprising: at least one pigment having attached at least one organic group having a calcium index value greater than a calcium index value of 1,2,3-benzene tricarboxylic acid; at least one acrylic polymer having an acid number of at least 150 KOH/g and a weight average molecular weight ranging from 1,000 to 15,000, wherein the at least one acrylic polymer is at least partially neutralized with a base having the following structure: wherein: A is a C2-C12 alkyl, R1 is selected from H, C1-C12 alkyl, an amine having the formula ‑NR3R4, and a guanidine residue having the formula -N(R5)‑C(=NH)‑N(R6)(R7), wherein R3 to R7 are independently selected from H and C1-C12 alkyl, and R2 is selected from H, C1-C12 alkyl, and an acid group. The inkjet ink composition further comprises an aqueous liquid medium.