Abstract: A thermochromic pigment composition comprising: (A) at least one electron-donor organic dye compound, (B) at least one electron-acceptor compound, and (C) at least one compound. The thermochromic pigment composition is microencapsulated and is useable in writing instruments.

Abstract: A compensation membrane for compensating a pressure difference between the outside and the inside of a free ink reservoir of a pen or the equivalent, the membrane comprising a first portion having a first rigidity, and a second portion having a second rigidity, the first rigidity being less than the second rigidity. A pen or the equivalent comprising a free ink reservoir provided with such a compensation membrane.

Abstract: The present invention concerns a solvent-free photocrosslinkable writing ink advantageously for a pen, comprising, as a percentage by weight relative to the total weight of the ink: a—between 40 and 75% of a photocrosslinkable acrylate and/or methacrylate oligomer, b—between 1 and 55%, optionally, of a photocrosslinkable acrylate and/or methacrylate monomer, c—between 0.5 and 6% of a photoinitiator, d—between 1 and 10% of a dye, advantageously a basic dye, and e—between 0 and 10% of an additive. It further concerns a method for securing a writing medium using said ink, the crosslinked ink obtained by crosslinking said ink and a pen for photo-crosslinkable ink comprising said ink.

Abstract: The present invention relates to a water-based correction fluid comprising a—a photocrosslinkable acrylate and/or methacrylate oligomer, b—a photoinitiator, c—an opacifying agent, and d—water, e—optionally a photocrosslinkable acrylate and/or methacrylate monomer, and d—optionally an additive, said fluid having a dry extract of between 40 and 80% by weight relative to the total weight of the fluid, advantageously between 54 and 66%, and forming a film after drying comprising at least 40% by weight of opacifying agent relative to the total weight of the film, advantageously between 40 and 80% by weight. It also relates to a device for applying the correction fluid and a process for covering a mark on a paper support using the correction fluid.