Non-aqueous Ink Jet Composition for Discharge Stability

The patent changes the particle size parameter of white pigment to 200-400 nm and adjusts solvent composition parameters (glycol diether content: 40-90 wt%, glycol monoether content: 20 wt% or less) to achieve both long-term storage stability and discharge stability. This parameter optimization resolves the contradiction by finding the optimal balance point where pigment aggregation is prevented during storage while maintaining stable discharge performance.

The patent uses a composite solvent system combining glycol diether and glycol monoether in specific proportions, along with composite pigment structures (white pigment particles in the 200-400 nm range). This composite approach allows the ink composition to simultaneously achieve long-term storage stability and discharge stability by leveraging the complementary properties of different materials in the composite system.

The patent optimizes the particle size parameter of white pigment to 200-400 nm, which is the critical parameter for achieving adequate covering ability. This parameter change ensures that pigment particles are small enough to disperse uniformly and provide good coverage, while still maintaining long-term storage stability. The specific particle size range prevents aggregation that would compromise either covering ability or storage stability.

The patent applies local quality by using glycol monoether specifically to control the local properties of the ink composition related to covering ability. The glycol monoether (content: 20 wt% or less) specifically influences the dispersion and coverage characteristics of the white pigment, while the glycol diether handles the bulk stability requirements. This localized functional assignment resolves the contradiction between storage stability and covering ability.

The patent identifies and optimizes the critical parameter of white pigment particle diameter to the specific range of 200-400 nm. This parameter optimization resolves the contradiction by finding the optimal balance point where particles are small enough for good covering ability (better than conventional larger particles) but not so small as to cause aggregation and discharge instability. The specific particle size range represents the optimal compromise between these two opposing requirements.

The patent effectively 'copies' or replicates the successful particle size distribution characteristics of conventional stable inks while improving upon them by using 200-400 nm particles instead of larger conventional particles. This allows the ink to achieve both discharge stability (by copying the stability approach) and improved covering ability (by using smaller particles).