A writing instrument, comprising a tubular body having a longitudinal axis with a first and a second end, and with an opening arranged in the first end; a first building block having a body part with a substantially plane surface and one or more coupling knobs extending from the substantially plane surface, and where the first building block is fixed onto the outside of the tubular body so that the coupling knobs extend away from said longitudinal axis.

A thermochromic writing instrument, comprising: a writing body, storing a thermochromic ink therein, stored in a barrel; an operation body provided in the barrel to be operated to longitudinally move the writing body; a nib of the writing body configured to be capable of appearing from a front end of the writing instrument, wherein the writing instrument further includes a friction unit, rubbing handwriting in the thermochromic ink and capable of thermally changing the color of the handwriting by frictional heat generated at that time, and at least one clip body as the operation body, the friction unit is provided at a rear end of the barrel, and the clip body is provided in an area other than the rear end of the barrel.

A writing and underline-drawing implement includes: an elongate hollow body having an open top portion and a closed bottom portion; an elongate core received in the elongate hollow body, the elongate core having the tip portion; a cap having a tip hole partially formed in a top portion thereof, the cap being hollow and having an open bottom portion to partially receive and/or passed through by the elongate core, the cap being configured to at least partially move along a length of the elongate hollow body; and rotatable guide wheels coupled to the cap at an upper portion of the cap, the cap being disposed between the guide wheels.

A writing and underline-drawing implement includes: an elongate hollow body having an open top portion and a closed bottom portion; an elongate core received in the elongate hollow body, the elongate core having the tip portion; a cap having a tip hole partially formed in a top portion thereof, the cap being hollow and having an open bottom portion to partially receive and/or passed through by the elongate core, the cap being configured to at least partially move along a length of the elongate hollow body; and rotatable guide wheels coupled to the cap at an upper portion of the cap, the cap being disposed between the guide wheels.

An ink reservoir unit for a writing instruments using an ink reservoir tube with which low contamination can be achieved considering environmental problems; and a writing instruments using the same. The ink reservoir tube is composed of a composite material in which a raw material is layered on a paper substrate having paper as a substrate. One end section of the ink reservoir tube is coupled to a connection part formed on a writing member or a relay member that holds the writing member to constitute the ink reservoir unit for a writing instrument. In one preferred aspect, a locking device using a male thread formed on an outer peripheral surface is provided to the connection part to be connected to the ink reservoir tube, and the ink reservoir tube is coupled to the relay member that holds the writing member by the locking device.

Angled pens are provided. A pen includes: a shank; an ink tube inside the shank; a first tip member connected to a distal end of the shank; a second tip member connected to a distal end of the first tip member; and a bent tubular member including a proximal end section, a middle section, and a distal end section. An axis of the middle section is arranged at a first angle relative to a central axis of the shank. The axis of the middle section is arranged at a second angle relative to an axis of the distal end section, the second angle being in a range of 45° to 90°. The axis of the distal end section is arranged at a third angle relative to the central axis of the shank.

Articulated pens are provided. A pen includes: a shank; an ink tube comprising a first section, a second section, a third section, and a fourth section; a writing tip connected to the fourth section; a first guide rail connected to the shank and that bends the ink tube at a first angle between the first section and the second section; and a second guide rail pivotally connected to the first guide rail and that bends the ink tube at a second angle between the third section and the fourth section. Pivoting the second guide rail relative to the first guide rail adjusts a third angle between the second section and the third section.

Articulated pens are provided. A pen includes: a shank; an ink tube comprising a first section, a second section, a third section, and a fourth section; a writing tip connected to the fourth section; a first guide rail connected to the shank and that bends the ink tube at a first angle between the first section and the second section; and a second guide rail pivotally connected to the first guide rail and that bends the ink tube at a second angle between the third section and the fourth section. Pivoting the second guide rail relative to the first guide rail adjusts a third angle between the second section and the third section.

The present disclosure relates to a method for preparing a thermochromic water-based gel ink composition, as well as a thermochromic water-based gel ink composition thereof comprising a specific monocarboxylic or polycarboxylic acid. The present disclosure also concerns a writing instrument, such as a ballpoint pen, a brush pen, a marker, a highlighter, and a felt pen, comprising a thermochromic water-based gel ink composition according to the disclosure.

Provided are thermochromic color-memorizing composition and thermochromic color-memorizing microcapsule pigment encapsulating the same, the thermochromic color-memorizing composition including: (a) an electron-donating color-developing organic compound; (b) an electron-accepting compound; and (c) an ester compound represented by the following formula (1) as a reaction medium which controls color reaction between the components (a) and (b):

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