Visible light activated printing ink
Inventors
Chow, Pui Keong • HUNG, Faan Fung • Liu, Chenmin • Kwok, Chi Ho
Assignees
Interested in licensing this patent?
MTEC can help explore whether this patent might be available for licensing for your application.
Publication Number
US-11466030-B2
Publication Date
2022-10-11
Expiration Date
Abstract
A visible light activated ink that produces a color change when exposed to visible light is provided. The ink includes a visible light activated photochromic compound, one or more binders, additives including one or more surfactants, and a solvent. The visible light activated ink is substantially colorless in the as-deposited state and requires a visible light intensity of approximately 300 W/m2 or greater at a wavelength of approximately 400-700 nm to produce a color change.
Core Innovation
The invention describes a visible light activated ink that includes a visible light activated photochromic compound and is formulated to be substantially colorless as deposited. The photochromic compound is selected from one or more π-extended conjugation heterocyclic compounds including naphthopyran, benzopyran, spirooxazine, spiropyran, fulgide, diarylethene, and/or perimidinespirocyclohexadienone. The ink is designed to undergo a reversible color change by visible light (400–700 nm), enabling security marking and anti-counterfeit measures.
The problem addressed is that UV-activated photochromics have limitations, including UV safety concerns and the need for visible-light activation instead. The ink is characterized as requiring a visible light intensity of approximately 300 W/m² or greater at a wavelength of approximately 400–700 nm to produce a color change. The document describes photo-physical characterization including visible absorption centered around ~529 nm and other absorption behavior, supporting visible-light activation.
The disclosed ink composition includes defined amounts of the visible light activated photochromic compound, one or more binders, additives including one or more surfactants, and a solvent. Example outcomes include a color change to purple upon visible-light excitation and bleaching back toward colorless in a time period described as about 10 minutes, and ink marking persistence described for offset printing. The document also describes the use of transparent coating film on PET and reports transmittance behavior as the film changes color under visible light.
Claims Coverage
The partial content identifies one independent claim directed to a visible light activated ink with specified photochromic compounds, composition ranges, and a minimum visible-light intensity requirement. Dependent claims mostly refine the independent claim by specifying particular photochromic compound subtypes, binder/resin selections, surfactant selections, and ink-type formulation details.
Visible light activated ink with π-extended conjugation heterocyclic photochromic compounds
A visible light activated ink comprising a visible light activated photochromic compound in an amount of approximately 0.2 to 20 weight percent selected from one or more of naphthopyran, benzopyran, spirooxazine, spiropyran, fulgide, diarylethene, and/or perimidinespirocyclohexadienone; one or more binders in an amount of approximately 10 to 45 weight percent; additives in an amount from approximately 2 to 8 weight percent, the additives including one or more surfactants; and a solvent in an amount of approximately 35 to 70 weight percent.
Visible-light intensity threshold for color change at 400–700 nm
The visible light activated ink wherein the visible light activated ink requires a visible light intensity of approximately 300 W/m2 or greater at a wavelength of approximately 400-700 nm to produce a color change.
Perimidinespirocyclohexadienone π-extended conjugation heterocyclic compound definition
A visible-light-activated ink wherein the visible-light-activated photochromic compound includes π-extended conjugation perimidinespirocyclohexadienone heterocyclic compounds defined by a specified chemical formula in which X is CH or N and R is selected from the listed substituent groups.
Binder selection from an enumerated group
The visible-light-activated ink wherein the binder is selected from a listed group of polymers and resins including rubbers, polyvinyl alcohol, styrene acrylic latex, polyurethane, acrylates, vinyl acrylates, vinyl acetates, methacrylates, styrene, acrylamides, methacrylamides, alkyds, phenolics, nitrocellulose, polyamides, poly(vinyl acetate), poly(vinyl butyral), and polyacrylics.
Surfactant selection including specified sorbitan derivatives
The visible light activated ink wherein the one or more surfactants are selected from polyethylene glycol sorbitan monolaurate and polyoxyethylenesorbitan monolaurate.
Inkjet ink composition wt% ranges and named binder/solvent selections
A definition of an inkjet ink composition specifying that the visible-light-activated photochromic compound is present at about 0.2–3 wt%, the binder at about 30–40 wt% selected from diethylene glycol monoethyl ethyl acetate, and the solvent at about 50–70 wt% selected from ethyl acetate.
Offset printing ink composition wt% ranges and named resin types
An offset printing ink composition specifying that the visible-light-activated photochromic compound is present at about 1–20 weight percent, along with additives (about 2–8 weight percent), a solvent (about 10–30 weight percent), and specified resins in an amount of about 25–90%.
Across the partial content, the claim coverage centers on a visible light activated ink formulation that uses specified π-extended conjugation heterocyclic photochromic compounds and includes defined binder, surfactant-containing additives, and solvent ranges, while requiring a minimum visible-light intensity threshold at 400–700 nm for color change. Dependent claims further specify particular photochromic compound families, enumerated binder selections, specific surfactants, and formulation details for inkjet and offset printing ink compositions.
Stated Advantages
Enables visible-light-driven color change for security marking and anti-counterfeit measures.
Avoids UV-activated photochromics limitations, including UV safety concerns.
Ink is substantially colorless as deposited and changes color upon visible light excitation and bleaches back toward colorless.
Provides measurable performance for visible-light activated color change including reported color change and bleaching/mark persistence behaviors.
Documented Applications
Security marking and anti-counterfeit measures using a visible-light-activated substantially colorless printing ink.
Inkjet ink formulation for producing visible-light-activated color change.
Offset printing ink formulation for visible-light-activated color change and described mark persistence.
Coating ink use as a transparent PET coating film that becomes purple upon visible-light activation with reported transmittance behavior.
Interested in licensing this patent?