Solvent-Based Ink Composition for Piezoelectric Inkjet Ejection Stability

The patent applies parameter changes by optimizing the average particle diameter of metal particles to a specific range (0.5 μm to 5 μm) and controlling the particle size distribution (specifically, limiting particles larger than 10 μm to 10% or less by number). This parameter optimization resolves the contradiction by finding the optimal balance point where ejection stability is sufficiently improved while glossiness is preserved.

The patent controls the aspect ratio of flaky metal particles within a specific range (1.05 to 3.0) to manage anisotropy. By limiting the aspect ratio, the patent reduces ejection defects caused by high anisotropic properties while still maintaining sufficient glossiness from the flaky shape. This parameter control resolves the contradiction between glossiness and ejection stability.

The patent optimizes the average particle diameter to 0.5 μm to 5 μm, avoiding excessive fineness that would reduce aspect ratio. This parameter setting ensures that metal particles maintain sufficient aspect ratio for glossy properties while being fine enough to achieve stable ejection. The controlled particle size prevents the degradation of aspect ratio that occurs with highly fine particles.

The patent uses a composite surface treatment approach by combining a fluorine-based surface treating agent with a specific organic solvent system. The fluorine-based agent provides glossy state while the carefully selected organic solvent (with specific physical properties including viscosity of 0.2 to 5.0 cP and surface tension of 15 to 40 mN/m) ensures good compatibility and dispersibility. This composite approach resolves the contradiction between glossiness and dispersibility.