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JP-7854795-B2 - Solid cursive writing instruments and writing instruments using them

JP7854795B2JP 7854795 B2JP7854795 B2JP 7854795B2JP-7854795-B2

Inventors

  • 小林 雅夫

Assignees

  • 株式会社パイロットコーポレーション

Dates

Publication Date
20260507
Application Date
20211215

Claims (8)

  1. Microcapsule pigments containing functional materials, excipient material, It comprises polyvinyl alcohol resin and polyamide resin, The excipient is polyolefin wax, The polyvinyl alcohol resin is a partially saponified polyvinyl alcohol having a degree of saponification of 3 to 50 mopl%, A solid writing instrument characterized in that the polyamide resin has a melting point of 50 to 150°C.
  2. The aforementioned functional material, (i) A component consisting of an electron-donating color-producing organic compound, (b) A component consisting of an electron-accepting compound, (c) A reaction medium that causes the electron transfer reaction by the components of (a) and (b) to occur reversibly in a specific temperature range, The solid writing material according to claim 1, which is a reversible thermochromic composition comprising the above.
  3. The solid writing material according to claim 1 or 2, wherein the weight-average molecular weight of the excipient is 1,000 to 100,000.
  4. A solid writing instrument according to any one of claims 1 to 3, wherein, based on the total mass of the solid writing instrument, the content of the polyvinyl alcohol resin is 5 to 30% by mass, and the content of the polyamide resin is 1 to 10% by mass.
  5. A solid writing instrument according to any one of claims 1 to 4, wherein the ratio of the polyamide resin content to the polyvinyl alcohol resin content is less than 1/1.
  6. A solid writing instrument according to any one of claims 1 to 5, having a cylindrical shape and an outer diameter of 0.3 to 3.5 mm.
  7. A mechanical pencil in which a solid writing instrument according to any one of claims 1 to 6 is held via a chuck and is arranged so as to extend the solid writing instrument as needed.
  8. The mechanical pencil according to claim 7, further comprising a friction member.

Description

This invention relates to a solid writing material capable of forming handwriting that changes color with temperature changes. More specifically, it relates to a solid writing material that is excellent in strength and color development, and in which discoloration abnormalities are suppressed. Solid writing materials such as colored pencils, which use wax and other excipients as fillers, have been known for some time. To improve the strength, moldability, and writing properties of these solid writing materials, it is known that inorganic fillers such as talc are added to enhance their performance. Furthermore, conventional solid cursive writing materials using reversible thermochromic compositions that can alternately retain the state before and after discoloration within a certain temperature range, such as room temperature, have been proposed (for example, Patent Document 1). The solid cursive writing materials described therein form writing that changes color with temperature changes by using a reversible thermochromic composition alone or its microcapsule-encapsulated form as a colorant added to the wax, which is the excipient. In particular, when using microcapsule pigments containing a heat-decolorizing type reversible thermochromic composition, the writing can be easily erased by frictional heat, resulting in a highly convenient cursive writing material that allows for correction of errors, and can be used, for example, for writing in notebooks and diaries, or for drawing. However, because the materials used in such solid cursive writing instruments are limited, they tend to be less strong than conventional solid cursive writing instruments. Therefore, the application of various materials is being considered to improve strength (for example, Patent Document 2). On the other hand, when attempting to achieve sufficient strength for use as a thin-diameter lead, such as for mechanical pencil leads, discoloration abnormalities sometimes occurred where the discoloration properties obtained by microcapsules containing the reversible thermochromic composition were not fully exhibited. Therefore, there was a need to develop a solid writing material that further improved both strength and discoloration properties without compromising writing performance or color development. Japanese Patent Publication No. 2009-166310Japanese Patent Publication No. 2020-105314 This graph shows the hysteresis characteristics in the color density-temperature curve of a heat-decolorizing, reversible thermochromic composition that can be used in the present invention. [Solid cursive] The solid writing material according to the present invention comprises microcapsule pigment, excipient, polyvinyl alcohol resin, and polyamide resin. The solid writing material according to the present invention uses microcapsules containing functional materials as pigments. Preferred functional materials include: (i) A component consisting of an electron-donating color-producing organic compound, (b) A component consisting of an electron-accepting compound, (c) A reaction medium that causes the electron transfer reaction by the components of (a) and (b) to occur reversibly in a specific temperature range, This is a reversible thermochromic composition comprising [a specific substance]. The reversible thermochromic microcapsule pigments that can be used in the present invention are described below. The reversible thermochromic microcapsule pigments can be arbitrarily selected from those conventionally known. For example, a reversible thermochromic microcapsule pigment containing a heat-decolorizing type (decolorizes upon heating and develops color upon cooling) with a relatively small hysteresis width ΔH (ΔH = 1 to 7°C) can be used. This pigment exhibits a decolorized state before and after a predetermined temperature (color change point), showing a decolorized state above the high-temperature color change point and a colored state below the low-temperature color change point. At room temperature, only one of these states exists; the other state is maintained while the heat or cold required to produce that state is applied, but returns to the state exhibited at room temperature when the application of heat or cold ceases. Furthermore, reversible thermochromic microcapsule pigments can also be applied, which contain a reversible thermochromic composition that exhibits greater hysteresis characteristics (ΔH = 8 to 50°C) than those described above. In other words, the shape of the curve plotting the change in color intensity due to temperature changes follows a significantly different path when the temperature is raised from a temperature below the color change temperature range compared to when it is lowered from a temperature above the color change temperature range. The colored state at low temperatures below the complete color development temperature ( T1 ) or the decolorized state at high temperatures above the complete decolorization temperature (