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 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.

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.

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.

A writing instrument may include an upper barrel rotatably connected to a lower barrel. Writing fluid reservoirs may be housed in the upper barrel. A writing tip secured to the lower barrel may be in selective fluid communication with the writing fluid reservoirs. The upper barrel may be rotatable relative to the lower barrel of the writing instrument.

A writing instrument may include an upper barrel rotatably connected to a lower barrel. Writing fluid reservoirs may be housed in the upper barrel. A writing tip secured to the lower barrel may be in selective fluid communication with the writing fluid reservoirs. The upper barrel may be rotatable relative to the lower barrel of the writing instrument.

A knock type writing tool is provided, in which an appropriate amount of air can be taken in depending on an amount of a thermochromic ink discharged from a pen tip, so that the thermochromic ink can be smoothly discharged from the pen tip, and in which a writing body can rotate surely in conjunction with a rotation of a rotating member. An air hole 63a and a plurality of projection pieces 63b are provided at a rear end portion of a writing body 6. A front surface of a projection and retraction rotating member 7 is provided with a plurality of abutment parts 73, on which respective rear ends of the plurality of projection pieces 63b are to abut, and with a plurality of protrusion parts 72, each of which is formed between the plurality of abutment parts 73 and protruded more forward than the plurality of abutment parts 73. The protrusion parts 72 are respectively inserted in gaps 63c between the projection pieces 63b. An axial length of each projection piece 63b is longer than an axial length of each protrusion part 72, so that a portion of the gap 63c is left more forward than a front end of each protrusion part 72.

The instant disclosure is directed to a heterogeneous fiber fluid reservoir for holding and delivering fluid. A reservoir may comprise a rod having a core component and a surrounding component. Each of the core component and the surrounding component may comprise fibers. The core component may have a first property, and the surrounding component may have a second property different from the first property, or the core component and the surrounding component may each have a different value or range of values for the same property. Alternatively, a reservoir may comprise a rod that includes fibers and has a cross-sectional diameter. At least one property of the rod may vary in value along the cross-sectional diameter of the rod. The property may include, for example, fiber bulk density, fiber diameter, fiber material, fiber morphology, fiber surface tension, capillary force, fluid absorption capacity, color, or combinations thereof.

A water-based ballpoint pen contains an aqueous ink composition in which resin particles having an average particle diameter of at least 0.3 μm are blended. The water-based ballpoint pen is provided with a ballpoint pen tip including a writing ball. The writing ball is formed from a mixture that includes a hard phase component comprising tungsten carbide, a binder phase component comprising cobalt and nickel, and chromium.

A water-based ballpoint pen contains an aqueous ink composition in which resin particles having an average particle diameter of at least 0.3 μm are blended. The water-based ballpoint pen is provided with a ballpoint pen tip including a writing ball. The writing ball is formed from a mixture that includes a hard phase component comprising tungsten carbide, a binder phase component comprising cobalt and nickel, and chromium.