Writing instrument

Patent metadata

Field	Value
Publication number	US-12325255-B2
Application number	US-202218718309-A
Country	US
Kind code	B2
Filing date	Dec 14, 2022
Priority date	Dec 17, 2021
Publication date	Jun 10, 2025
Grant date	Jun 10, 2025

Abstract

A writing instrument in which condensation does not occur in a cap even though the writing instrument is equipped with the cap and which has high writing instrument quality and commercial value. The writing instrument includes at least a barrel in which an aqueous ink is contained; a pen tip provided on a tip side of the barrel and capable of discharging the aqueous ink; and a cap that is removably attached on a pen tip side of the barrel, wherein the aqueous ink has a vapor pressure of 10.3 to 12.3 kPa at 50° C.

First claim

The invention claimed is:

1. A writing instrument comprising at least:
a barrel in which an aqueous ink is contained;
a pen tip provided on a tip side of the barrel and capable of discharging the aqueous ink; and
a cap that is removably attached on a pen tip side of the barrel, wherein
the aqueous ink has a vapor pressure of 10.3 to 12.3 kPa at 50° C.

2. The writing instrument according to claim 1 , wherein the aqueous ink further contains a water-soluble betaine.

3. The writing instrument according to claim 2 , wherein the pen tip has a window portion through which a writing direction is visible.

4. The writing instrument according to claim 1 , wherein the pen tip has a window portion through which a writing direction is visible.

5. The writing instrument according to claim 1 , wherein an inner surface of the cap is subjected to a hydrophilization treatment.

Assignees

• Mitsubishi Pencil Co

Inventors

• Kamitani Toshimi
• Mochizuki Chihiro
• Sagawa Wataru

Classifications

• C09D11/16 Primary

  Writing inks · CPC title

• B43K23/12

  for pens {(caps co-operating with retractable nibs B43K5/165)} · CPC title

• B43K23/08

  Protecting means, e.g. caps · CPC title

• B43K8/03

  Ink reservoirs; Ink cartridges · CPC title

• B43K8/02

  with writing-points comprising fibres, felt, or similar porous or capillary material (B43K8/22 takes precedence) · CPC title