JP7664321B2 - Writing implements - Google Patents

Description

The present invention relates to a writing instrument, in particular a double-ended writing instrument.

There are known so-called double-ended writing instruments that have writing parts at both ends of the barrel (for example, see Patent Document 1). The double-ended writing instrument described in Patent Document 1 has two caps that can be detachably fitted to either end (Patent Document 1).

Japanese Utility Model Application Publication No. 2-8995

The cap described in Patent Document 1 may not be able to obtain sufficient fitting force due to deformation. That is, the cap described in Patent Document 1 has a fitting portion at the open end, which fits into the fitting portion of the corresponding barrel. The open end of the cap is easily deformed due to its shape. As a result, if the double-ended writing instrument described in Patent Document 1 is used for a long period of time, the fitting portion of the cap may not fit properly with the fitting portion of the barrel, and the cap may be removed unintentionally. In particular, in the case of a writing instrument such as that described in Patent Document 1 in which the writing portion of the writing body is positioned at a position away from the central axis of the barrel rather than on the central axis, the open end of the cap is not circular, so it is more likely to deform depending on the direction of the applied force. In addition, if the cap is configured to be used as an erasing member, it is more likely to deform by gripping it tightly during the erasing operation.

The present invention aims to provide a writing instrument with a cap that can be securely fitted to the barrel.

According to one aspect of the present invention, there is provided a writing instrument comprising a barrel, a writing part provided at least on one end of the barrel, and a cap covering the writing part and having a non-circular opening end that fits into the barrel, the writing part being located at a position away from the central axis of the barrel, and the fitting position of the cap and the barrel being away from the vicinity of the opening end of the cap.

The writing part may be provided at both ends of the barrel, and the two caps may cover each of the writing parts. The caps may be axially symmetric. The caps may be capable of being fitted to both ends of the barrel. The writing instrument is a thermochromic writing instrument, and in order to optimally obtain the functions of both the cap and the color changing instrument, the surface hardness of the cap may be 50 or more and less than 80 in durometer D hardness.

The aspects of the present invention have the common effect of providing a writing instrument with a cap that can be securely fitted to the barrel.

FIG. 1 is a perspective view of a double-ended writing instrument according to an embodiment of the present invention. FIG. 2 is a perspective view of the double-ended writing instrument of FIG. 1 with the cap removed. FIG. 3 is a vertical cross-sectional view of the double-ended writing instrument of FIG. FIG. 4 is another vertical cross-sectional view of the double-ended writing instrument of FIG. FIG. 5 is a vertical cross-sectional view of the barrel. FIG. 6 is a perspective view of the mounting member. FIG. 7 is a vertical cross-sectional view of the mounting member. FIG. 8 is a perspective view of the cap. FIG. 9 is a vertical cross-sectional view of the cap. FIG. 10 is an enlarged view of the portion X in FIG. FIG. 11 is an enlarged view of a portion Y in FIG. FIG. 12 is a front view of a double-ended writing instrument set.

The following describes in detail an embodiment of the present invention with reference to the drawings. Corresponding components are designated by the same reference symbols throughout the drawings.

Figure 1 is a perspective view of a double-ended writing instrument 1 according to an embodiment of the present invention, Figure 2 is a perspective view of the double-ended writing instrument 1 of Figure 1 with the cap 30 removed, Figure 3 is a vertical cross-sectional view of the double-ended writing instrument 1 of Figure 1, and Figure 4 is another vertical cross-sectional view of the double-ended writing instrument of Figure 1.

The double-ended writing instrument 1 has two refills 2, which are writing bodies with a writing part 3 at one end, a barrel 10 with a clip 11 on the side, two attachment members 20, and two caps 30. Inside the barrel 10, each of the two refills 2 is arranged in parallel. The double-ended writing instrument 1 attaches the writing part 3, specifically the refills 2, to the barrel 10 by fitting the two attachment members 20 to each end of the barrel 10. The barrel 10 may be referred to as including the fitted attachment members 20.

Unless otherwise specified, "axis" or "central axis" refers to the central axis of the double-ended writing instrument 1. In the axial direction of the double-ended writing instrument 1 or barrel 10, the end opposite the side on which the clip 11 is provided is referred to as the first end A, and the end on the side on which the clip 11 is provided is referred to as the second end B. For the refill 2, the side on which the writing part 3 is located is defined as the "front" side, and the side opposite the writing part 3 is defined as the "rear" side.

Figure 5 is a longitudinal cross-sectional view of the barrel 10. The barrel 10 is formed in a cylindrical shape. The cross-sectional shape of the barrel 10 is generally elliptical or flat, but may be rectangular. In the transverse direction of the barrel 10, the side on which the clip 11 is provided is referred to as the first side 12, and the side opposite to the side on which the clip 11 is provided is referred to as the second side 13. The first side 12 and the second side 13 are made of a curved surface or multiple flat surfaces extending in the axial direction, and the first side 12 and the second side 13 are connected by two flat surfaces 14 arranged in parallel (Figures 1 to 4). A through hole 15 extending in the axial direction is formed in the portion of the first side 12 facing the clip 11.

A first recess 16 is formed on the inner surface near the open end of the first end A on the first side surface 12 side, and a second recess 17 is formed on the second side surface 13 side. A third recess 18 is formed on the inner surface near the open end of the second end B on the second side surface 13 side. Engagement protrusions 19 are formed facing each other on the inner surface of each flat surface 14 in a portion closer to the second end B side than the center in the axial direction.

Figure 6 is a perspective view of the mounting member 20, and Figure 7 is a longitudinal cross-sectional view of the mounting member 20. The mounting member 20 is a hollow member overall, and has an insertion portion 21 that is inserted and fitted into the shaft tube 10, and a holding portion 22 that is exposed to the outside of the shaft tube 10 when fitted into the shaft tube 10.

When the mounting member 20 is attached to the barrel 10, the insertion portion 21 has a wide engagement recess 23 formed at a position corresponding to the engagement protrusion 19 of the barrel 10, i.e., on the outer surface near the open end of the mounting member 20. When the mounting member 20 is attached to the barrel 10, the insertion portion 21 has a first protrusion 24 formed at a position corresponding to the first recess 16 of the barrel 10, and a second protrusion 25 formed at a position corresponding to the second recess 17 of the barrel 10.

The holder 22 has a tip 26. The tip 26 has a shape similar to the tip of a general writing instrument that is not a double-ended writing instrument. Thus, the tip 26 has a truncated cone-shaped portion continuing from a cylindrical portion, and has an opening at the top for allowing the writing part 3 of the refill 2 to protrude. An annular protrusion 27 is formed on the outer circumferential surface of the cylindrical portion of the tip 26.

When the mounting member 20 is attached to the barrel 10, the tip 26 is formed biased toward either the first side 12 or the second side 13, and a slope 28 is formed on the other side of the corresponding first side 12 or second side 13. A plurality of ribs 29 extending in the axial direction are formed on the inner surface of the holding portion 22. On the inner surface of the holding portion 22, the rib 29 formed on the tip 26 side holds the front end of the refill 2 arranged on the tip 26 side, and the rib 29 formed on the slope 28 side holds the rear end of the refill 2 arranged on the slope 28 side.

8 is a perspective view of the cap 30, and FIG. 9 is a longitudinal cross-sectional view of the cap 30. The cap 30 is a member that covers the writing part 3 of the refill 2 to protect it, and has an axially symmetrical shape. Because of its axially symmetrical shape, the cap 30 can be attached to the barrel 10 even when rotated 180° in the circumferential direction. One end of the cap 30 is open, and the other end of the cap 30 is closed except for the ventilation hole 31. The open end of the cap 30 is formed in a non-circular shape as a whole. Two notches 32 are formed at the open end of the cap 30 corresponding to the flat surface 14 of the barrel 10, and a gripping part 33 consisting of multiple grooves is formed on the outer surface of the cap 30 next to the two notches as a slip prevention. Two opposing separation walls 34 are formed on the inner surface of the cap 30 separated from the vicinity of the open end. A plurality of small protrusions 35 are formed in a substantially identical cross section including the separation walls 34. The ventilation hole 31 is preferably designed to allow ventilation if a small child or other person accidentally swallows the cap 30. If the ink contained in the refill 2 is easily volatile, the ventilation hole 31 does not need to be provided in order to prevent the ink from drying out.

Next, the assembly of the double-ended writing instrument 1 will be described. As shown in FIG. 3, in the barrel 10, one refill 2 is arranged on the first side surface 12 side, and its writing part 3 protrudes outward from the first end A. The other refill 2 is arranged on the second side surface 13 side, and its writing part 3 protrudes outward from the second end B. Therefore, in the double-ended writing instrument 1, both refills 2, i.e., both writing parts 3, are arranged at positions away from the central axis of the barrel 10 and do not coincide with the central axis. Note that, in the barrel 10, the writing part 3 of the refill 2 arranged on the first side surface 12 side may be configured to protrude outward from the second end B, and the writing part 3 of the refill 2 arranged on the second side surface 13 side may be configured to protrude outward from the first end A.

The refill 2 is fixed in the barrel 10 by being held by the two mounting members 20. That is, in FIG. 3, in the refill 2 arranged on the first side 12 side, the front end is held by the rib 29 on the tip 26 side of the mounting member 20 that fits into the first end A of the barrel 10, and the rear end is held by the rib 29 on the slope 28 side of the mounting member 20 that fits into the second end B of the barrel 10. On the other hand, in the refill 2 arranged on the second side 13 side, the front end is held by the rib 29 on the tip 26 side of the mounting member 20 that fits into the second end B of the barrel 10, and the rear end is held by the rib 29 on the slope 28 side of the mounting member 20 that fits into the first end A of the barrel 10.

The cap 30 fits into the tip 26 of the mounting member 20. In detail, the small protrusions 35 of the cap 30 overcome and engage the annular protrusions 27 of the tip 26, thereby fitting the mounting member 20 and the cap 30 together. The small protrusions 35 of the cap 30 are formed on the inside, away from the vicinity of the open end of the cap 30. In other words, the fitting position between the cap 30 and the mounting member 20, i.e., the shaft tube 10, is away from the vicinity of the open end of the cap 30. Therefore, even if the open end of the cap 30 is deformed, the part of the cap 30 where the small protrusions 35 are located, which are located inside the open end, will not be deformed. Therefore, the deformation of the open end of the cap 30 does not affect the fitting between the tip 26 of the mounting member 20 and the cap 30, and the cap 30 can be firmly fitted to the shaft tube 10.

The fitting position being away from the vicinity of the open end of the cap 30 means that the fitting position is away from the open end or the vicinity of the open end to an extent that the vicinity of the fitting position of the cap 30 is not deformed, for example, near the writing part 3 or closer to the writing part 3. Therefore, as long as the fitting position is away from the vicinity of the open end of the cap 30, any configuration and arrangement of the protrusions can be adopted.

The cap 30 can be fitted to both ends of the barrel 10, i.e., to each of the mounting members 20 fitted to both ends. When the cap 30 is fitted to the mounting member 20, the refill 2 and the corresponding tip 26 are disposed on one side within the cap 30, separated by a separation wall 34. The internal space defined between the cap 30 and the mounting member 20 is preferably less than 1200 ^mm3 .

Figure 10 is an enlarged view of part X in Figure 3, i.e., the first end A. As shown in Figure 10, the first recess 16 of the barrel 10 has a recess 16a formed near the open end and an engagement protrusion 16b formed further inside the barrel 10 than the recess 16a. The second recess 17 of the barrel 10 has a recess 17a formed near the open end and an engagement protrusion 17b formed further inside the barrel 10 than the recess 17a. The recess 16a of the first recess 16 is formed so that its axial length is shorter than that of the recess 17a of the second recess 17. The third recess 18 also has a recess 18a similar to the first recess 16 formed near the open end (Figure 5).

The first convex portion 24 of the mounting member 20 has a protrusion 24a formed to be complementary to the recess 16a of the first recess 16, and an engagement protrusion 24b formed closer to the opening end than the protrusion 24a. The second convex portion 25 of the mounting member 20 has a protrusion 25a formed to be complementary to the recess 17a of the second recess 17, and an engagement protrusion 25b formed closer to the opening end than the protrusion 25a.

As shown in FIG. 10, when the mounting member 20 is attached to the barrel 10, the engagement protrusion 16b of the barrel 10 engages with the engagement protrusion 24b of the mounting member 20 on the first side 12 of the barrel 10, and the engagement protrusion 17b of the barrel 10 engages with the engagement protrusion 25b of the mounting member 20 on the second side 13 of the barrel 10. This ensures that the mounting member 20 fitted to the first end A will not easily come off the barrel 10. The engagement protrusions 24b and 25b of the mounting member 20 form a first engagement portion that engages with the barrel 10.

When the mounting member 20 is rotated 180 degrees around the central axis, for example, when the tip 26 of the mounting member 20 at the first end A is positioned on the second side surface 13 side, the mounting member 20 cannot be fitted to the shaft tube 10. That is, as shown in FIG. 10, the recess 16a of the first recess 16 is formed so that its axial length is shorter than the recess 17a of the second recess 17. Therefore, even if an attempt is made to insert the mounting member 20 into the shaft tube 10 in this state, the protrusion 25a of the second protrusion 25 abuts against the wall surface of the recess 16a of the first recess 16, preventing the mounting member 20 from being inserted.

Similarly, when fitting the mounting member 20 to the second end B of the barrel 10, the mounting member 20 can be fitted when the first protrusion 24 of the mounting member 20 is positioned on the third recess 18 side of the barrel 10, but cannot be fitted when the second protrusion 25 of the mounting member 20 is positioned on the third recess 18 side of the barrel 10. Therefore, the mounting member 20 is formed to fit into the barrel 10 only at a predetermined position around the central axis of the barrel 10. As a result, fitting the mounting member 20 into the barrel 10 in the wrong direction is prevented, and the mounting member 20 can be fitted in the intended direction.

Figure 11 is an enlarged view of the Y portion in Figure 4. As described above, the inner surface of each flat surface 14 has an engagement protrusion 19 formed facing each other in a portion closer to the second end B than the center in the axial direction. Therefore, as shown in Figure 11, the mounting member 20 inserted into the second end B has an engagement recess 23 that engages with the engagement protrusion 19 of the shaft tube 10. As a result, the mounting member 20 fitted into the second end B is configured not to easily come off the shaft tube 10. The engagement recess 23 of the mounting member 20 constitutes a second engagement portion that engages with the shaft tube 10. Note that the mounting member 20 inserted into the first end A does not have an engagement protrusion 19 formed on the inner surface of the corresponding shaft tube 10, so the engagement recess 23 does not engage with the shaft tube 10.

As described above, the mounting member 20 has a first engagement portion and a second engagement portion, one of the mounting members 20 engages with the shaft tube 10 by the first engagement portion, and the other of the mounting member 20 engages with the shaft tube 10 by the second engagement portion. Therefore, even if there is dimensional variation in each of the mounting members 20 during manufacturing, the engagement positions with the shaft tube 10 are different from each other, so that it is possible to minimize the effect. As a result, there is an effect that there is no rattle between the mounting member 20 and the shaft tube 10. In addition, as long as such an effect is achieved, the configuration and arrangement of the first engagement portion and the second engagement portion can be arbitrarily adopted in two mounting members 20 having the same shape. In the above-mentioned embodiment, the first engagement portion and the second engagement portion are arranged apart in the axial direction.

As shown in FIG. 1, when the cap 30 is fitted to the barrel 10, a part of the mounting member 20 is exposed from the cutout 32 of the cap 30. Therefore, by making the mounting member 20 the same color as the ink contained in the refill 2 held by the mounting member 20, it is possible to know the ink color of the writing part 3 covered by the cap 30 even when the cap 30 is fitted to the barrel 10. As shown in FIG. 3, the double-ended writing instrument 1 has two refills 2 arranged in parallel over most of the axial direction within the barrel 10. Therefore, the double-ended writing instrument 1 can be constructed with approximately the same overall length while using the same refill as a normal writing instrument that accommodates one refill in the barrel.

By arranging the two refills 2 side by side, a flat surface 14 with a larger area than the barrel of a normal writing instrument can be formed on the outer surface of the barrel 10. As a result, it becomes possible to apply various designs to the flat surface 14. For example, a name may be inscribed on the flat surface 14 for gift-giving purposes. In addition, a company name or logo may be applied for advertising purposes. As shown in Figures 1 and 2, the outer surface of the mounting member 20 is exposed from the through hole 15 of the barrel 10. Further designs may be applied to this exposed outer surface of the mounting member 20. Furthermore, by making multiple sets of double-ended writing instruments 1, a continuous, integrated design may be applied.

Figure 12 is a front view of a double-ended writing instrument set 100. In the double-ended writing instrument set 100, the barrels 10 of the multiple double-ended writing instruments 1, specifically the flat surfaces 14, are provided with designs 101 that form a continuous, integrated whole when the writing instruments are placed adjacent to each other in the same orientation. Here, the design refers to letters, symbols, pictures, shapes (including three-dimensional shapes), patterns, colors, or combinations of these. The double-ended writing instrument set 100 is made up of three double-ended writing instruments 1, but may be made up of two or four or more double-ended writing instruments 1. As an example of the design 101, the alphabet "NA" is shown in Figure 12.

Each of the multiple double-ended writing instruments 1 in the double-ended writing instrument set 100 may have a different design that is complete on its own. For example, in a double-ended writing instrument set 100 having two double-ended writing instruments 1, a picture of a boy may be placed on the barrel 10 of one double-ended writing instrument 1 and a picture of a girl may be placed on the barrel 10 of the other double-ended writing instrument 1, and when these are lined up, the design may look like a boy and a girl standing side by side in harmony. Also, one letter of the alphabet may be placed on each of the multiple double-ended writing instruments 1, and by placing them adjacent to each other, it may become one's own name.

The design 101 is applied, for example, by transferring a film. By forming an image on the transfer film using an inkjet method that does not have a solid white layer, it is possible to create a double-ended writing instrument set 100 that has excellent decorativeness and a high novelty effect. The design 101 may also be applied by painting, engraving, etc.

In order to arrange the double-ended writing instrument sets 100 more neatly and to display them in stores, the double-ended writing instrument sets 100 may be housed in a writing instrument case. The writing instrument case may be a box-shaped case with at least the front being transparent so that the integrated design 101 can be seen. Note that the writing instrument case may not be box-shaped, but may be a rectangular bag-like envelope-like case or another shape, as long as a portion of the case is transparent so that the design 101 can be seen.

The materials used for the writing implement case are resin materials such as PP, PE, PET, PEN, nylon (including amorphous nylon in addition to common nylons such as nylon 6 and nylon 12), acrylic, polymethylpentene, polystyrene, ABS, etc., and glass materials, and it is desirable for the case to be made of a material with a visible light transmittance of 50% or more, more preferably 80% or more. The visible light transmittance can be determined by measuring the reflectance using a multi-light source colorimeter. Furthermore, discoloration and fading of the printed design 101 can be prevented by including a benzotriazole-based compound, a benzophenone-based compound, a salicylate-based compound, etc. as an ultraviolet absorbing agent.

The double-ended writing instrument set 100 has a unified design when multiple double-ended writing instruments 1 are placed next to each other, which has the effect of making users want to purchase multiple double-ended writing instruments 1 as a set.

The refill 2 may be a ballpoint pen refill, a marking pen, a touch pen, an eraser, a friction body, or other types of refills. The two refills 2 may be combined with each other in different colors, different writing widths (ball diameters), etc. The cap 30 may also be an erasing member for erasing handwriting made by the double-ended writing instrument 1.

At least one of the refills 2 may be a refill containing a thermochromic ink containing a thermochromic coloring material. In this case, the double-ended writing instrument 1 may be a thermochromic writing instrument, and the cap 30 may be a friction body serving as an erasing member. Handwriting made by the double-ended writing instrument 1 can be thermochromic due to frictional heat generated when rubbed by the cap 30.

Here, thermochromic ink refers to ink that has the property of maintaining a predetermined color (first color) at room temperature (e.g., 25°C), changing to another color (second color) when heated to a predetermined temperature (e.g., 60°C), and then returning to the original color (first color) when cooled to a predetermined temperature (e.g., -5°C). In a double-ended writing instrument 1 using thermochromic ink, the second color is made colorless, and the term "erasing" refers to heating a line drawn in the first color (e.g., red) to make it colorless. Thus, the line is rubbed against the writing surface on which it was drawn with a friction body to generate frictional heat, which changes the drawn line to colorless, i.e., erases it. Of course, the second color may be a color other than colorless.

The thermochromic microencapsulated pigment that serves as the thermochromic coloring material is not particularly limited as long as it has the ability to change color due to heat such as frictional heat, for example, from colored to colorless, from colored to colored, or from colorless to colored, and various types can be used, and examples of such materials include microencapsulated thermochromic compositions that contain at least a leuco dye, a color developer, and a color change temperature regulator.

The leuco dyes that can be used are not particularly limited, so long as they are electron-donating dyes that function as color-developing agents. Specifically, in order to obtain inks with excellent color-developing properties, conventionally known dyes such as triphenylmethane, spiropyran, fluoran, diphenylmethane, rhodamine lactam, indolylphthalide, and leucoauramine can be used alone (one type) or in a mixture of two or more types (hereinafter simply referred to as "at least one type").

Specifically, 6-(dimethylamino)-3,3-bis[4-(dimethylamino)phenyl]-1(3H)-isobenzofuranone, 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide, 3-(4-diethylaminophenyl)-3-(1-ethyl-2-methylindol-3-yl)phthalide, 3-(4-diethylamino-2-ethoxyphenyl)-3-(1-ethyl-2-methylindol-3-yl)- 4-Azaphthalide, 1,3-dimethyl-6-diethylaminofluoran, 2-chloro-3-methyl-6-dimethylaminofluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-xylidinofluoran, 2-(2-chloroanilino)-6-dibutylaminofluoran, 3,6-dimethoxyfluoran, 3,6-di -n-butoxyfluoran, 1,2-benz-6-diethylaminofluoran, 1,2-benz-6-dibutylaminofluoran, 1,2-benz-6-ethylisoamylaminofluoran, 2-methyl-6-(N-p-tolyl-N-ethylamino)fluoran, 2-(N-phenyl-N-methylamino)-6-(N-p-tolyl-N-ethylamino)fluoran, 2-(3'-trifluoromethylanilino)-6-diethylamino Nofluoran, 3-chloro-6-cyclohexylaminofluoran, 2-methyl-6-cyclohexylaminofluoran, 3-di(n-butyl)amino-6-methoxy-7-anilinofluoran, 3,6-bis(diphenylamino)fluoran, methyl-3',6'-bisdiphenylaminofluoran, chloro-3',6'-bisdiphenylaminofluoran, 3-methoxy-4-dodecoxystyrinoquinoline, etc.

These leuco dyes have a lactone skeleton, a pyridine skeleton, a quinazoline skeleton, a bisquinazoline skeleton, etc., and color is generated by opening these skeletons (rings).

The color developer that can be used is a component that has the ability to cause the leuco dye to develop color, and examples of such compounds include phenolic resin compounds, salicylic acid metal chlorides, salicylic acid resin metal salt compounds, and solid acid compounds.

Specifically, o-cresol, tertiary butyl catechol, nonylphenol, n-octylphenol, n-dodecylphenol, n-stearylphenol, p-chlorophenol, p-bromophenol, o-phenylphenol, hexafluorobisphenol, n-butyl p-hydroxybenzoate, n-octyl p-hydroxybenzoate, resorcinol, dodecyl gallate, 2,2-bis(4'-hydroxyphenyl)propane, 4,4-dihydroxydiphenyl sulfone, 1,1-bis(4'-hydroxyphenyl)ethane, 2,2-bis(4'-hydroxy-3-methylphenyl)propane, bis(4-hydroxyphenyl)sulfide, 1-phenyl-1,1-bis( 1,1-bis(4'-hydroxyphenyl)ethane, 1,1-bis(4'-hydroxyphenyl)-3-methylbutane, 1,1-bis(4'-hydroxyphenyl)-2-methylpropane, 1,1-bis(4'-hydroxyphenyl)n-hexane, 1,1-bis(4'-hydroxyphenyl)n-heptane, 1,1-bis(4'-hydroxyphenyl)n-octane, 1,1-bis(4'-hydroxyphenyl)n-nonane, 1,1-bis(4'-hydroxyphenyl)n-decane, 1 , 1-bis(4'-hydroxyphenyl)n-dodecane, 2,2-bis(4'-hydroxyphenyl)butane, 2,2-bis(4'-hydroxyphenyl)ethyl propionate, 2,2-bis(4'-hydroxyphenyl)-4-methylpentane, 2,2-bis(4'-hydroxyphenyl)hexafluoropropane, 2,2-bis(4'-hydroxyphenyl)n-heptane, 2,2-bis(4'-hydroxyphenyl)n-nonane, etc. are at least one of them.

The amount of developer used can be selected according to the desired color density and is not particularly limited, but it is usually preferable to select an amount within the range of about 0.1 to 100 parts by weight per 1 part by weight of the leuco dye described above.

The discoloration temperature regulator that can be used is a substance that controls the discoloration temperature in the color development of the leuco dye and the color developer. The discoloration temperature regulator that can be used is any of those that are conventionally known. Specific examples include alcohols, esters, ketones, ethers, acid amides, azomethines, fatty acids, and hydrocarbons.

More specifically, at least one of bis(4-hydroxyphenyl)phenylmethane dicaprylate (C ₇ H ₁₅ ), bis(4-hydroxyphenyl)phenylmethane dilaurate (C ₁₁ H ₂₃ ), bis(4-hydroxyphenyl)phenylmethane dimyristate (C ₁₃ H ₂₇ ), bis(4-hydroxyphenyl)phenylethane dimyristate (C ₁₃ H ₂₇ ), bis(4-hydroxyphenyl)phenylmethane dipalmitate (C ₁₅ H ₃₀ ), bis(4-hydroxyphenyl)phenylmethane dibehenate (C ₂₁ H ₄₃ ), bis(4-hydroxyphenyl)phenylethylhexylidene dimyristate (C ₁₃ H ₂₇ ) and the like can be mentioned.

The amount of the discoloration temperature regulator used can be appropriately selected depending on the desired hysteresis width and color density at the time of color development, and is not particularly limited, but it is usually preferable to use it in the range of about 1 to 100 parts by weight per 1 part by weight of the leuco dye.

The thermochromic microencapsulated pigment can be produced by microencapsulating a thermochromic composition containing at least the above leuco dye, color developer, and color change temperature regulator so that the average particle size is 0.2 to 5 μm. Examples of microencapsulation methods include interfacial polymerization, interfacial polycondensation, in situ polymerization, liquid curing coating, phase separation from an aqueous solution, phase separation from an organic solvent, melt dispersion cooling, air suspension coating, and spray drying, and can be appropriately selected depending on the application.

For example, in the phase separation method from an aqueous solution, the leuco dye, developer, and discoloration temperature regulator are heated and melted, then added to an emulsifier solution, heated and stirred to disperse them into oil droplets, and then a resin raw material is gradually added as a capsule membrane agent, such as an amino resin solution or an isocyanate resin solution, and the mixture is allowed to react and then filtered to produce the desired thermochromic microcapsule pigment.

The content of these leuco dyes, color developers, and color change temperature regulators varies depending on the type of leuco dyes, color developers, and color change temperature regulators used, the microencapsulation method, etc., but the mass ratio is 0.1 to 100 parts of color developer and 1 to 100 parts of color change temperature regulator per 1 part of the dye. The mass ratio of the capsule membrane agent to the capsule contents is 0.1 to 1.

The thermochromic microcapsule pigment can be set to an appropriate temperature for each color's color development temperature (for example, color development at 0°C or higher) and color loss temperature (for example, color loss at 50°C or higher) by appropriately combining the types and amounts of the above-mentioned leuco dye, color developer, and color change temperature regulator, and it is preferable that the color changes from colored to colorless due to heat such as frictional heat.

In the case of thermochromic microcapsule pigments, in order to further improve the line density, storage stability, and writing ability, it is preferable that the wall film is formed of a urethane resin, a urea/urethane resin, an epoxy resin, or an amino resin. Examples of urethane resins include compounds of isocyanate and polyol. Examples of epoxy resins include compounds of epoxy resin and amine. Examples of amino resins include melamine resin, urea resin, and benzoguanamine resin. The thickness of the wall film of the microcapsule color material is appropriately determined depending on the required wall film strength and line density.

The average particle diameter of the thermochromic microencapsulated pigment is preferably 0.2 to 5 μm, and more preferably 0.3 to 3 μm, from the standpoints of colorability, color development, ease of fading, stability, fluidity in the ink, suppression of adverse effects on writing, and compatibility with the photochromic microencapsulated pigment described below. The "average particle diameter" specified here is the value obtained by measuring the average particle diameter (50% diameter) (refractive index 1.8) using a particle size analyzer [Microtrac HRA9320-X100 (manufactured by Nikkiso)].

If the average particle size is less than 0.2 μm, sufficient line density cannot be obtained, while if it exceeds 5 μm, it is undesirable because it deteriorates writing properties, reduces the dispersion stability of the thermochromic microencapsulated pigment, and is prone to ink back caused by vibration. Furthermore, the 90% diameter is 8 μm or less, preferably 6 μm or less. If a certain proportion of particles with large diameters are present, the above-mentioned effects tend to become more pronounced. Note that the microencapsulated pigment that falls within the above-mentioned average particle size range (0.2 to 5 μm) varies depending on the microencapsulation method, but in a phase separation method from an aqueous solution, it can be prepared by appropriately combining the stirring conditions when manufacturing the microencapsulated pigment.

The specific gravity of the thermochromic microencapsulated pigment is in the range of 0.9 to 1.3, preferably 1.0 to 1.2. If the specific gravity is outside this range, the dispersion stability of the microencapsulated pigment is likely to decrease. Furthermore, microencapsulated pigments with a specific gravity exceeding 1.3 are prone to ink back caused by vibration.

In addition to the thermochromic microencapsulated pigment, the aqueous ink composition for writing instruments may contain water (tap water, purified water, distilled water, ion-exchanged water, pure water, etc.) as the solvent as the remainder, and may also contain water-soluble organic solvents, thickeners, lubricants, rust inhibitors, preservatives, or antibacterial agents as appropriate, within the scope of not impairing the effects of the agent, depending on the intended use of the writing instrument (ballpoint pen, marking pen, etc.).

Examples of water-soluble organic solvents that can be used include glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, polyethylene glycol, 3-butylene glycol, thiodiethylene glycol, and glycerin, as well as ethylene glycol monomethyl ether and diethylene glycol monomethyl ether, which can be used alone or in combination.

Of these, it is preferable to use glycerin to prevent ink solidification at the writing area due to the ink bag, and the amount added is preferably 1 to 10% by mass of the total amount of ink. The mechanism of action of glycerin is unknown, but it is presumed to have the effect of reducing the cohesive force between the pigment and ink components in a dry state.

As the thickener that can be used, for example, at least one selected from the group consisting of synthetic polymers, cellulose, and polysaccharides is preferable. Specific examples include gum arabic, tragacanth gum, guar gum, locust bean gum, alginic acid, carrageenan, gelatin, xanthan gum, welan gum, succinoglycan, diutan gum, dextran, methylcellulose, ethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, starch glycolic acid and its salts, propylene glycol alginate, polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl methyl ether, polyacrylic acid and its salts, carboxyvinyl polymer, polyethylene oxide, copolymer of vinyl acetate and polyvinylpyrrolidone, crosslinked acrylic acid polymer and its salts, non-crosslinked acrylic acid polymer and its salts, styrene acrylic acid copolymer and its salts, etc.

Of these, it is preferable to use polysaccharides. Due to their rheological properties, polysaccharides tend to be less susceptible to the effects of vibration on fluidity, and are less likely to cause problems such as poor writing caused by ink bag. Xanthan gum is particularly preferable, as it provides an excellent balance with other properties required of writing instrument inks.

Lubricants include fatty acid esters of polyhydric alcohols, which are also used as surface treatment agents for pigments, higher fatty acid esters of sugars, polyoxyalkylene higher fatty acid esters, alkyl phosphate esters, alkyl sulfonates of higher fatty acid amides, alkyl aryl sulfonates, polyalkylene glycol derivatives, fluorine-based surfactants, polyether-modified silicones, etc. Rust inhibitors include benzotriazole, tolyltriazole, dicyclohexylammonium nitrite, saponins, etc. Preservatives or antibacterial agents include phenol, sodium omadine, sodium benzoate, benzimidazole-based compounds, etc.

This aqueous ink composition for writing instruments can be produced by a conventional method, for example, by blending the thermochromic and photochromic microencapsulated pigments and the other aqueous components in predetermined amounts and stirring and mixing them with a stirrer such as a homomixer or a disperser. If necessary, coarse particles in the ink composition may be removed by filtration or centrifugation.

The viscosity value of the aqueous ink composition for writing instruments is preferably 500 to 2000 mPa·s at 25° C. and a shear rate of 3.83/s, and 20 to 100 mPa·s at a shear rate of 383/s. By setting the viscosity within the above range, an ink having excellent writing properties and stability over time can be obtained. Furthermore, the non-Newtonian viscosity index n calculated by the viscosity formula S=αD ⁿ (where 1>n>0) (S is shear stress (dyn/cm ² ), D is shear rate (s ⁻¹ ), and α is a non-Newtonian viscosity coefficient) is preferably 0.2 to 0.6. By setting the non-Newtonian viscosity index n within the above range in addition to the above viscosity range, it is possible to appropriately set the fluidity of the ink against vibration, and it is possible to prevent the occurrence of ink back.

The surface tension of the aqueous ink composition for writing instruments is preferably 25 to 45 mN/m, and more preferably 30 to 40 mN/m. Within this range, the balance between the wettability of the inside of the pen tip and the ink is appropriate, making it possible to prevent the occurrence of ink back.

In the refill, an ink follower may be placed immediately behind the ink. The material constituting the follower may be composed of at least a non-volatile or low-volatility organic solvent and a thickener. The non-volatile or low-volatility organic solvent used in the ink follower is used as the base oil of the ink follower, and liquid paraffin is used, for example. Mineral oil and chemically synthesized oil are used for the liquid paraffin, and polybutene, poly-α-olefin, ethylene α-olefin oligomer, etc. can be used as the chemically synthesized oil.

Specific examples of mineral oils that can be used include Diana Process Oil NS-100, PW-32, PW-90, NR-68, and AH-58 (manufactured by Idemitsu Kosan Co., Ltd.).

Specific examples of polybutenes that can be used include polybutene 200N, polybutene 30N, polybutene 10N, polybutene 5N, polybutene 3N, polybutene 015N, polybutene 06N, polybutene 0N (all manufactured by Nippon Oil & Fats Corporation), polybutene HV-15 (manufactured by Nippon Petrochemical Industry Co., Ltd.), and 35R (manufactured by Idemitsu Kosan Co., Ltd.).

Specific examples of poly-α-olefins that can be used include barrel process oils P-26, P-46, P-56, P-150, P-350, P-1500, P-2200, P-10000, and P-37500 (manufactured by Matsumura Oil Co., Ltd.).

Specific examples of ethylene α-olefin oligomers that can be used include LUCANT HC-10, HC-20, HC-100, HC-150, HC-600, and HC-2000 (all manufactured by Mitsui Chemicals, Inc.).

These non-volatile or low-volatile organic solvents can be used alone or in combination of two or more.

Examples of thickeners used in the ink follower include calcium salts of phosphate esters, fine silica particles, block copolymers of polystyrene-polyethylene/butylene rubber-polystyrene, block copolymers of polystyrene-polyethylene/propylene rubber-polystyrene, hydrogenated styrene-butadiene rubber, block copolymers of styrene-ethylenebutylene-olefin crystals, block copolymers of olefin crystals-ethylenebutylene-olefin crystals, and acetoalkoxyaluminum dialkylates, and these may be used alone or in combination of two or more.

Preferred materials for calcium salts of phosphate esters that can be used include Crodax DP-301LA (manufactured by Croda Japan Co., Ltd.). Usable fine particle silica includes hydrophilic fine particle silica and hydrophobic fine particle silica. Preferred commercial products of hydrophilic silica include AEROSIL-300 and AEROSIL-380 (manufactured by Nippon Aerosil Co., Ltd.), and preferred materials for hydrophobic silica include AEROSIL-974D and AEROSIL-972 (manufactured by Nippon Aerosil Co., Ltd.).

Preferable materials for the polystyrene-polyethylene/butylene rubber-polystyrene block copolymer include Kraton GFG-1901X and Kraton GG-1650 (both manufactured by Shell Japan), Septon 8007 and Septon 8004 (both manufactured by Kuraray Co., Ltd.), etc. Furthermore, preferable materials for the polystyrene-polyethylene/propylene rubber-polystyrene block copolymer include Kraton GG-1730 (manufactured by Shell Japan), Septon 2006 and Septon 2063 (both manufactured by Kuraray Co., Ltd.), etc.

Preferred hydrogenated styrene-butadiene rubber materials include DYNARON 1320P, DYNARON 1321P (both manufactured by JSR Corporation), Tuftec H1041, and Tuftec H1141 (both manufactured by Asahi Chemical Industry Co., Ltd.).

Preferred materials for styrene-ethylenebutylene-olefin crystal block copolymers include DYNARON 4600P (manufactured by JSR Corporation), and preferred materials for olefin crystal-ethylenebutylene-olefin crystal block copolymers include DYNARON 6200P and DYNARON 6201B (manufactured by JSR Corporation).

Preferred materials for acetoalkoxyaluminum dialkylate include PLENACT AL-M (manufactured by Ajinomoto Fine-Techno Co., Ltd.).

Among these thickeners, in order to further exert the effects of the present invention, it is preferable to use thermoplastic olefin-based elastomers such as styrene-ethylenebutylene-olefin crystalline block copolymers and olefin crystalline-ethylenebutylene-olefin crystalline block copolymers.

Furthermore, in order to obtain an ink follower that prevents the occurrence of ink back, it is preferable that the average tan δ value measured for each frequency while exponentially increasing in the frequency range of 1 to 63 rad/s is 1.0 or more, and more preferably 1.7 to 3.4.

Here, tan δ is a value that means the loss modulus/storage modulus, and it has been known in the past that the average tan δ value measured for each frequency while exponentially increasing in the frequency range "1 to 63 rad/s" is preferably 1.0 or less. In the present invention, by making the average tan δ value measured for each frequency in the above 1 to 63 rad/s 1.0 or more, it becomes possible to absorb vibrations and prevent the occurrence of ink back.

As materials for forming the friction body that changes the color of the thermochromic ink, synthetic resins such as polyacetal and polypropylene, and mixtures of rubber elastic materials and the above synthetic resins can be used, and the friction body is formed by configuring it so that the Taber abrasion amount on the abrasion wheel CS-17 of the Taber abrasion tester is less than 25 mg under a load of 9.8 N and an environment of 1000 rpm in the abrasion test specified in JIS K7204 (ASTM D1044).

The surface of the friction body preferably has a durometer D hardness of 50 or more and less than 80 as specified in JIS K 7215-1986. This ensures a hardness suitable for the function of the cap, which fits into the barrel to protect the writing part, and the function of the friction body, which discolors the handwriting, allowing for a more stable rubbing action. The friction body can also be used as a touch pen or stylus pen, and may be made conductive.

The friction body is preferably colored with a color having a lower brightness value than the color of the thermochromic ink contained in the refill. In other words, if the thermochromic ink is transferred to the surface of the friction body without discoloring during use of the friction body, the transfer of the thermochromic ink can be made less noticeable. In particular, by making the color of the friction body black or having a brightness value of 2.5 or less, it is possible to make the stains on the surface of the friction body that occur during use less noticeable.

The brightness value is measured using the Munsell color system with a measuring device such as a general-purpose color difference meter (TC-8600A, manufactured by Tokyo Denshoku Co., Ltd.), the brightness value of the friction body is measured on the surface, and the brightness value of the thermochromic ink is obtained by measuring the ink on a line drawn on a paper surface (old JIS P3201; wood-free paper made from 100% chemical pulp, basis weight range 40-157 g/m2, whiteness 75.0% or more) at a writing speed of 4.5 m/min with a pitch interval of 0.1 mm.

In addition, at least one of the refills 2 in the above-mentioned embodiment may be a refill containing pencil lead or eraser-erasable ink, and the remaining refills 2 may be refills containing thermochromic ink. In this case, by making the cap 30 a plastic eraser or eraser, handwriting made with mechanical pencil lead, pencil lead, or eraser-erasable ink can be erased. Furthermore, handwriting made with thermochromic ink can be thermally discolored by rubbing it with a plastic eraser or eraser to generate frictional heat.

Therefore, a plastic eraser or rubber eraser can be used as an erasing member for different types of handwriting, i.e., it can be used as an erasing member for erasing handwriting made with pencil lead or eraser-erasable ink, and as a friction body for thermally discoloring (erasing) handwriting made with thermochromic ink. Note that the ability to erase handwriting using a plastic eraser or rubber means that handwriting can be erased by rubbing the handwriting with a plastic eraser or rubber without soiling the paper surface around the handwriting.

The pencil lead preferably contains, for example, 3 to 80% by weight of glass powder in flake form with an average thickness of 0.1 to 2 μm, an aspect ratio of 5 to 150, and a flatness of 200 nm or less, in which at least one type of fine particle (excluding glass powder) selected from inorganic pigments, organic pigments, and dyes is dispersed or encapsulated as a compound composition before firing, or glass powder in granular form with an average particle size of 0.1 to 50 μm and a sphericity of 0.1 to 50 μm.

The eraser-erasable ink preferably contains at least 5-30% by weight of non-thermoplastic colored resin particles with an average particle size of 2-20 μm relative to the total amount of the ink composition, and non-colored particles with a glass transition point of less than 0°C. As mentioned above, the "average particle size" specified here is the value obtained by measuring the average particle size (50% diameter) (refractive index 1.8) using a particle size analyzer [Microtrac HRA9320-X100 (manufactured by Nikkiso)].

In this case, the friction body contains, in addition to the friction body described above, an acrylic thermoplastic resin powder having a primary particle size of 20 to 80 μm, which is composed of a shell with a relatively high glass transition temperature (Tg) and a core with a relatively lower glass transition temperature (Tg) than the shell, a plasticizer, an inorganic powder, and a thermoplastic resin, in which the thermoplastic resin is polyvinyl chloride resin or a copolymer thereof, and the inorganic powder is calcium carbonate and/or magnesium carbonate, since both the thermochromic ink mark and the erasable ink mark can be affected by rubbing. The "glass transition temperature (Tg)" refers to the temperature at which the mobility of the non-crystalline portion of the acrylic resin powder increases and it becomes rubbery.

In addition, at least one of the refills 2 in the above-mentioned embodiment may be a refill containing a non-thermochromic ink, and the remaining refills 2 may be a refill containing a thermochromic ink. In this case, the cap 30 corresponding to the refill containing the non-thermochromic ink may be formed of a material having a higher bending elasticity than the friction body such as hard plastic. As a result, it is possible to recognize whether the ink contained in the corresponding refill is non-thermochromic ink or thermochromic ink by the touch when attaching or detaching the cap 30. Furthermore, by making the non-thermochromic ink achromatic and the thermochromic ink chromatic, it is possible to make a writing instrument suitable for learning. Note that achromatic colors refer to colors that have only a colorless brightness, such as white, gray, and black, and chromatic colors refer to colors that have a color and brightness, hue, and saturation, such as red, green, and blue.

REFERENCE SIGNS LIST 1 double-ended writing implement 2 refill 3 writing part 10 barrel 16 first recess 17 second recess 19 engagement protrusion 20 attachment member 23 engagement recess 24 first protrusion 25 second protrusion 30 cap 35 minute protrusion

Claims (1)

The pen comprises a barrel, a writing part provided at at least one end of the barrel, and a cap having a non-circular opening end that covers the writing part and fits into the barrel,
The internal space formed by the cap and the barrel is less than 1200 ^mm3 ;
The surface hardness of the cap is 50 or more and less than 80 in terms of durometer D hardness;
The writing part is disposed at a position spaced apart from the central axis of the barrel,
A writing implement, characterized in that two opposing separation walls are formed on the inner surface of the cap .

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