High opacity permanent ink formulations comprising a solvent, a polymer-based opacifier, a coloring agent, a resin, and a humectant, wherein the ink formulation displays a viscosity of less than about 50 cP, are provided herein.

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 liquid ink instrument, including: a pen body, a writing element mounted on the head of the pen body, an ink absorber mounted at the rear end of the writing element; a fiber ink feeder mounted in the body penetrates the ink absorbing body, the front end in contact with the writing element, the rear end communicated with the ink cartridge; at least one air-liquid balancer in the axial direction, the air-liquid balancer installed between the recited fiber ink feeder and the body; having one or more air-liquid exchange grooves penetrating through the outer circumferential surface; having an overflow groove on a radial surface of the air-liquid balancer, one end contacted to fiber ink feeder, and the other end communicating with air-liquid exchange groove; a gas-free fit or an interference fit adopted between the outer circumferential surface of the fiber ink feeder and the inner wall of the air-liquid balancer.

A liquid ink instrument, including: a pen body, a writing element mounted on the head of the pen body, an ink absorber mounted at the rear end of the writing element; a fiber ink feeder mounted in the body penetrates the ink absorbing body, the front end in contact with the writing element, the rear end communicated with the ink cartridge; at least one air-liquid balancer in the axial direction, the air-liquid balancer installed between the recited fiber ink feeder and the body; having one or more air-liquid exchange grooves penetrating through the outer circumferential surface; having an overflow groove on a radial surface of the air-liquid balancer, one end contacted to fiber ink feeder, and the other end communicating with air-liquid exchange groove; a gas-free fit or an interference fit adopted between the outer circumferential surface of the fiber ink feeder and the inner wall of the air-liquid balancer.

Disclosed is a thermochromic writing tool which includes a writing element including a reservoir in which thermochromic ink is retained, and a writing point portion which is disposed on a front end portion of the reservoir and from which the thermochromic ink is dischargeable; a barrel which is made of a resin and in which the writing element is accommodated so as to be movable in a longitudinal direction; a protruding and retracting mechanism including a push element made of a resin and disposed on a rear end portion of the barrel so as to be tiltable in a radial direction relative to an axis of the barrel; and a rub portion disposed on a rear end portion of the push element 5.

A refill for a writing tool includes an ink containing tube that is made from a resin material and formed in a straight cylindrical shape, and a writing tip that is attached to an end of the ink containing tube. A press-fit portion, formed at the end of the ink containing tube, has a thickness being made thickened toward an inner circumferential surface and has an opening hole penetrating in an axial direction at a central portion of the press-fit portion. The writing tip or a relay member supporting the writing tip is press-fitted and attached to the press-fit portion. The refill for a writing tool can ensure a necessary and sufficient amount of ink stored without expanding an outer diameter of the ink containing tube, and sufficiently secure mechanical strength of an end portion, and a writing tool using the same can be provided.

A refill for a writing tool includes an ink containing tube that is made from a resin material and formed in a straight cylindrical shape, and a writing tip that is attached to an end of the ink containing tube. A press-fit portion, formed at the end of the ink containing tube, has a thickness being made thickened toward an inner circumferential surface and has an opening hole penetrating in an axial direction at a central portion of the press-fit portion. The writing tip or a relay member supporting the writing tip is press-fitted and attached to the press-fit portion. The refill for a writing tool can ensure a necessary and sufficient amount of ink stored without expanding an outer diameter of the ink containing tube, and sufficiently secure mechanical strength of an end portion, and a writing tool using the same can be provided.

A thermochromic writing instrument including 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 1 further includes a friction unit, for 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 10 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 including 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 1 further includes a friction unit, for 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 10 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.