| abstract |
This invention applies to methods for creating opaque indicia on substrate surfaces and to non-pigmented, moisture-free, jet ink compositions containing only solvents and solvent soluble resins and dyes that exhibit the acceptable characteristics of opacity, contrast, adhesion to non-pigmented, moisture-free, jet ink compositions containing only solvents and solvent soluble resins and dyes that exhibit the acceptable characteristics of opacity, contrast, adhesion and machine compatibility. The compositions are on weight percentage basis as stated below. The compositions contain a combination of film forming resins of varying weight average molecular weights of a dry resin solids percentage between 8 and 15%. The resins are chosen from the following: nitrates of cellulose; acrylics; alkyds; vinyl acetate-vinyl chloride copolymers; and styrene acrylic. The quantities of resin are chosen according to the desired viscosity, adhesion strength of film on the subject substrate and the degree of shearing of the drying resin mixture. An optimum balance of adhesion and opacity is stoichiometrically obtained. The differential solubilities of the resins in the solvent-blend is the prime moving factor of the opacifying action. The use of acid dyes and basic salts that exhibit fluorescence is considered and used in the formulations to enhance the visibility and contrast of the resultant opacified dried state of resin solids on the substrate surface. The use of specific plasticizers are another feature of this invention. Plasticizers are used in the ink jet composition to increase the flowability of the composition and also increase the tensile strength and adhesion of the ink to the substrate to which it is applied. The principle of this invention is that a water-free, multi-solvent and multi-resin jet ink which characteristically forms micro laminate miscelli and plasticizers is found to have good adhesion and opacity, and can be used to mark code and indicate non-absorbent dark substrates, and can be used to provide an opaque indicia on substrates that loses opacity upon wetting with polar aqueous liquids and regains opacity upon drying of said indicia. |