# US 12,180,379 B2 · Reverse photochromic inks including encapsulated reverse photochromic colorants, and associated methods and writing instruments

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- Number: US 12,180,379 B2
- Document ID: US12180379B2
- Status: Granted
- Kind: B2
- Application number: 17/761,771
- Filed: 2020-09-23
- Published: 2022-11-24
- Granted: 2024-12-31
- Earliest claimed: 2019-09-24
- Assignees: Sanford, L.P.
- Applicants: Sanford L.P.
- Inventors: Kenneth Czaplewski
- Web page: https://patentgrep.com/patent/US12180379B2

## CPC

- C09D 11/50: Sympathetic, colour changing or similar inks
- C09D 11/17: characterised by colouring agents
- C09D 11/18: specially adapted for ball-point writing instruments
- C09D: COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR (cosmetics A61K; processes for applying liquids or other fluent materials to surfaces, in general, B05D; staining wood B27K5/02; glazes or vitreous enamels C03C; natural resins, French polish, drying-oils, driers, turpentine, per se, C09F; polishing compositions other than French polish, ski waxes C09G; adhesives or use of materials as adhesives C09J; materials for sealing or packing joints or covers C09K3/10; materials for stopping leaks C09K3/12; processes for the electrolytic or electrophoretic production of coatings C25D)

## Abstract

Reverse photochromic ink formulations containing encapsulated reverse photochromic colorant, methods of erasing reverse photochromic ink formulations including encapsulated reverse photochromic colorants by exposing them to UV light, and writing instruments including a writing tip portion connected to a light-shielding tubular member or refill and a reverse photochromic ink formulation including encapsulated reverse photochromic colorant are provided herein.

## Claims

### Claim 1

An ink formulation comprising a reverse photochromic colorant encapsulated in a plurality of capsules, wherein the plurality of capsules are formed of one or more UV absorbers.

### Claim 2 (depends on 1)

The ink formulation of claim 1, wherein the plurality of capsules are nanocapsules or microcapsules.

### Claim 3 (depends on 1)

The ink formulation of claim 1, wherein the capsules are formed of one or more polymers, wherein the capsules are formed of melamine formaldehyde or an acrylic polymer.

### Claim 4 (depends on 1)

The ink formulation of claim 1, further comprising a solvent, wherein the ink formulation contains the solvent in an amount of from about 20 wt. % to about 80 wt. %.

### Claim 5 (depends on 4)

The ink formulation of claim 4, wherein the solvent comprises water.

### Claim 6 (depends on 4)

The ink formulation of claim 4, wherein the solvent comprises an alcohol, wherein the alcohol is benzyl alcohol, ethanol, n-propanol, n-butanol, diacetone alcohol, or any combination thereof.

### Claim 7 (depends on 1)

The ink formulation of claim 1, further comprising a resin in an amount from about 0.01 wt. % to about 50 wt. %.

### Claim 8 (depends on 1)

The ink formulation of claim 1, wherein the one or more UV absorbers comprise contain 2 (5-benzotriazolyl 3-t-butyl 4-methacryloxy) phenyl propionic acid, isooctyl ester; 2-(2′-Hydroxy-5′-methylphenyl)-benzotriazole; 2-(2′-Methacryloxy-5′-methylphenyl) benzotriazole; Phenyl acrylate; Phenyl methacrylate; 2-Phenylethyl acrylate; 2-Phenylethyl methacrylate; N-(Phthalimidomethyl) acrylamide; dicyclopentenyloxyethyl acrylate; 4-methacryloxy-2-hydroxybenzophenone; 2-(2′-Methacryloxy-5′-methylphenyl) benzotriazole; diallyl maleate; phenylmethacrylate; 2-phenylethyl acrylate; 2-phenylmethacrylate; phenyl acrylate; n-phthalimidomethyl) acrylamide; cinnamyl methacrylate; benzyl acrylate; or combinations thereof.

### Claim 9

A method of erasing ink comprising:
disposing an ink formulation comprising a reverse photochromic colorant encapsulated in a plurality of capsules on a surface, wherein the plurality of capsules are formed of one or more UV absorbers;
rupturing at least a portion of the plurality of capsules; and
exposing the surface to UV light, wherein the rupturing at least a portion of the plurality of capsules occurs before exposing the surface to UV light.

### Claim 10 (depends on 9)

The method of claim 9, wherein rupturing the at least a portion of the plurality of capsules comprises applying heat to the surface.

### Claim 11 (depends on 9)

The method of claim 9, wherein the UV light comprises 340 nm UV light or 365 nm UV light.

### Claim 12 (depends on 9)

The method of claim 9, wherein exposing the surface to UV light comprises exposing the surface to less than 11,000 mJ/cm2 of 340 nm UV light, or less than 100,000 mW/cm2 of 340 nm UV light.

### Claim 13 (depends on 9)

The method of claim 9, further comprising disposing a UV absorbing formulation on the ink formulation disposed on the surface, prior to exposing the surface to UV light,
wherein the UV absorbing formulation comprises a UV absorber.

### Claim 14 (depends on 13)

The method of claim 13, wherein the UV absorbing formulation contains the UV absorber in an amount of from about 1 wt. % to about 20 wt. %.

### Claim 15 (depends on 13)

The method of claim 13, wherein the UV absorber comprises 2-hydroxy-benzophenone, oxalanilide, 2-(2-hydroxyphenyl)-benzotriazole, hydroxyphenyl-s-triazine (“HPT”), any derivatives thereof, or any combination thereof.

### Claim 16 (depends on 13)

The method of claim 13, wherein the UV absorbing formulation further comprises a solvent in an amount of from about 20 wt. % to about 80 wt. %.

### Claim 17 (depends on 13)

The method of claim 13, wherein the UV absorbing formulation further comprises a resin in an amount of from about 10 wt. % to about 50 wt. %.

### Claim 18

A method of erasing ink comprising:
disposing an ink formulation comprising a reverse photochromic colorant encapsulated in a plurality of capsules on a surface, wherein the plurality of capsules are formed of one or more UV absorbers; and
exposing the surface to UV light,
wherein, after exposing the surface to UV light, the surface has a ΔE* value of from about 1 to about 20, a ΔL* value of from about 0.1 to about 3, a Δa* value of from about +/−0.5 to about +/−2, a Δb* value of from about +/−0.5 to about +/−5, or any combination thereof.

### Claim 19 (depends on 1)

The ink formulation of claim 1, further comprising an activator or bleaching agent.