# US 12,110,401 B2 · Aqueous ink composition for writing instrument

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- Number: US 12,110,401 B2
- Document ID: US12110401B2
- Status: Granted
- Kind: B2
- Application number: 16/965,529
- Filed: 2019-01-21
- Published: 2021-02-18
- Granted: 2024-10-08
- Earliest claimed: 2018-01-29
- Assignees: Mitsubishi Pencil Company, Limited
- Applicants: Mitsubishi Pencil Company, Limited
- Inventors: Kousuke Ogura; Akiko Hirayama; Kana Miyoshi
- Web page: https://patentgrep.com/patent/US12110401B2

## CPC

- C09D 11/17: characterised by colouring agents
- B01J 13/02: Making microcapsules or microballoons {(for medical preparations A61K9/50)}
- C09D 11/18: specially adapted for ball-point writing instruments
- C09D 17/00: Pigment pastes, e.g. for mixing in paints (artists' paints C09D5/06)
- C09D 17/001: {in aqueous medium (C09D17/003, C09D17/004 take precedence)}
- C09D 17/005: {Carbon black}
- C09D 17/007: {Metal oxide}
- 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)
- B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS

## Abstract

Provided is an aqueous ink composition for a writing instrument with excellent stability of ink flow and the like, in which aggregation of a microcapsule pigment and clogging due to such aggregation are suppressed. The aqueous ink composition for a writing instrument includes a microcapsule pigment which includes inside, at least, a pigment and a medium of a fatty acid polyol ester. A melting point of the fatty acid polyol ester is preferably 40° C. or higher, and is preferably 70° C. or lower.

## Claims

### Claim 1

An aqueous ink composition for a ballpoint pen, including inside a microcapsule pigment including, at least, a pigment and a medium of a fatty acid polyol ester,
wherein the fatty acid polyol ester is an ester constituted of a fatty acid and a polyol selected from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, glycerin, sorbitan, sorbitol, pentaerythritol, dipentaerythritol, and trimethylolpropane, and
wherein a melting point of the fatty acid polyol ester is 40° C. or higher and 70° C. or lower.

### Claim 2 (depends on 1)

The aqueous ink composition for a ballpoint pen described in claim 1, wherein a shell component forming microcapsules is urethane, urea, or urea-urethane.

### Claim 3 (depends on 1)

The aqueous ink composition for a ballpoint pen described in claim 1, wherein a content of the fatty acid polyol ester is 5 to 70% by mass based on a total amount of microcapsule components.

### Claim 4 (depends on 1)

The aqueous ink composition for a ballpoint pen described in claim 1, wherein the pigment is an inorganic pigment.

### Claim 5 (depends on 1)

The aqueous ink composition for a ballpoint pen described in claim 1, wherein the pigment is titanium oxide or carbon black.