KR100369814B1 - Writing Instrument for White Board - Google Patents

Abstract

The outer cylinder is formed in a predetermined shape and both ends in the longitudinal direction are opened, and the rotating device is rotatably assembled to the outer cylinder so that the powder does not fly during erasing and writing is possible even after long-term storage with the cap open. A moving device which is inserted to be movable in the longitudinal direction and assembled to the rotating device so as to move forward and backward in the longitudinal direction of the outer cylinder as the rotating device rotates, and solid ink supported by the moving device and movably inserted into the outer cylinder. It provides a writing instrument for writing.

The rotating device is composed of a rotating member rotatably assembled to the outer cylinder and an operating member rotatably inserted into the outer cylinder and the moving device is assembled therein. It consists of a support member which supports a part of shape ink using elasticity.

The solid ink is formed by microencapsulating and solidifying an ink composition mixed with a solvent, a colorant, and a resin release agent using a film forming material, or by using a fatty acid salt, which is a solid composition, of an ink composition mixed with a solvent, a colorant, and a release agent. It is achieved by solidification.

Description

Writing Instrument for Writing {Writing Instrument for White Board}

The present invention relates to a writing instrument for writing board, which uses a solid ink that can be written even after long-term storage in a state in which the powder is not blown upon erasing and supports a solid ink by using elasticity.

In general, for writing boards such as white boards, a writing instrument called a white board pen or a board pen for a white board board is used.

The writing instrument for writing board is a method of writing through a fibrous tip by storing a liquid ink composition comprising a colorant, a resin release agent, and a solvent in a fibrous tip, and writing through a fibrous tip while keeping the ink itself in an ink reservoir. There is a way.

When writing on the writing board using a conventional writing instrument for writing boards as described above, erase is performed by friction using an eraser.

In the above-described writing instrument for writing board, liquid ink is used, so that the colorant and the release agent in the composition are sedimented and separated in the fiber absorbent body or the ink storage container, thereby causing the writing line to be light and partially erasing property.

In addition, when the evaporation of the solvent rapidly occurs and the cap is left open, the ink dries at the tip of the writing instrument and solidifies, so that writing is not performed smoothly when it is to be used again.

In addition, the conventional apparatus for supporting and moving solids such as pools uses a method such as inserting a support having protrusions inside the solid, and thus, the support is difficult to perform injection molding.

In addition, when the solids are almost used up, the support is protruded and the rest cannot be used. Therefore, the amount of the solids discarded is large, and when used as a writing instrument, the remaining writing is impossible due to the support.

An object of the present invention is to solve the above problems, it is possible to write smoothly, the powder does not fly during erasing, separation and sedimentation of the ink composition does not occur, solid ink that can be written after long-term storage even in the cap open state It is to provide a writing instrument for writing board configured to support using the elastic.

1 is an exploded perspective view showing an embodiment of a writing instrument for writing board according to the present invention.

Figure 2 is an assembled cross-sectional view showing an embodiment of a writing instrument for writing board according to the present invention.

3 is a cross-sectional view taken along the line A-A of FIG.

Figure 4 is an assembled cross-sectional view showing a state using about half of the solid ink in one embodiment of the writing instrument for writing board according to the present invention.

5 is a cross-sectional view showing an embodiment of a rotating member according to the present invention.

6 is a cross-sectional view taken along the line B-B in FIG. 5.

Figure 7 is a cross-sectional view showing an embodiment of the operating member according to the present invention.

Figure 8 is a plan view showing an embodiment of the operating member according to the present invention.

Figure 9 is a cross-sectional view showing an embodiment of the outer cylinder according to the present invention.

10 is a plan view showing an embodiment of the outer cylinder according to the present invention.

Figure 11 is a partially enlarged cross-sectional view showing an embodiment of a moving device according to the present invention.

12 is a plan view showing an embodiment of a moving device according to the present invention.

The writing instrument for writing board proposed by the present invention is formed in a predetermined shape and has an outer cylinder having both ends in the longitudinal direction open, a rotating device rotatably assembled at one end of the outer cylinder, and a longitudinal direction inside the outer cylinder. A moving device inserted into the rotary device so as to move forward and backward in the longitudinal direction of the outer cylinder as the rotary device is rotated forward or reverse, and supported by the moving device and Solid ink that is movably inserted therein.

The rotating device is a rotating member rotatably assembled at one end of the outer cylinder, and made to rotate integrally with the rotating member and is rotatably inserted into the inside of the outer cylinder, the moving device is inside It consists of an operating member assembled to.

The rotating member and the operating member may be integrally formed, or may be configured to be separately manufactured and assembled.

The moving device includes a screw member in which a male screw is formed to a predetermined length, and a support member configured to move integrally with the screw member and to support a portion of the solid ink using elasticity.

The screw member and the support member may be integrally formed, or may be configured to be separately manufactured and assembled.

The solid ink is formed by microencapsulating and solidifying an ink composition obtained by mixing a solvent, a colorant, and a resin release agent using a film forming material.

The solid ink may be formed by solidifying an ink composition obtained by mixing a solvent, a colorant, and a release agent by using a fatty acid salt as a solid forming material.

Next, a preferred embodiment of a writing instrument for writing board according to the present invention will be described in detail with reference to the drawings.

First, an embodiment of the writing instrument for writing board according to the present invention, as shown in Figures 1 and 2, the outer cylinder (2) formed in a predetermined shape and both ends in the longitudinal direction open, and one of the outer cylinder (2) Rotating device 10 is rotatably assembled at the end, and is inserted into the inside of the outer cylinder 2 to be movable in the longitudinal direction and the outer cylinder (2) as the rotating device 10 is rotated forward or reverse A moving device 30 assembled to the rotating device 10 so as to move forward or backward in the longitudinal direction of a) and supported by the moving device 30 and movably inserted into the outer cylinder 2. Solid ink 50, which is used.

One embodiment of the writing instrument for writing board according to the present invention is assembled to the other end of the outer cylinder 2, as shown in Figs. 1 and 2, the exposed portion of the solid ink 50 It is protected by blocking the outside and further comprises a lid 40 is formed with a clip 42 that can be inserted into a collar or pocket collar on one side.

The inner surface of the end portion assembled to the outer cylinder 2 of the lid 40 forms a coupling protrusion 44 protruding inward along the circumference.

The other end of the outer cylinder 2 is engaged with the engaging projection 44 of the lid 40 to form a engaging projection 4 for maintaining the assembled state.

In addition, the lid 40 is provided with a discharge hole 46 for releasing the internal air to the outside when assembling the outer cylinder (2) to facilitate the assembly work.

As shown in FIGS. 1 and 2 and 5 to 8, the rotating device 10 includes a rotating member 12 rotatably assembled at one end of the outer cylinder 2, and the above-described rotation. It consists of an operating member 20 which is made to rotate integrally with the member 12 and is rotatably inserted into the outer cylinder 2 and the moving device 30 is assembled therein.

The rotating member 12 and the operation member 20, as shown in Figures 1 and 5 to 8, are separately manufactured and assembled to rotate integrally.

That is, at least one assembly groove 13 is formed in the rotation member 12 in the longitudinal direction, and at least one assembly protrusion fitted to the assembly groove 13 at the lower end of the operation member 20. To form (22).

Formed as described above, the assembly protrusion 22 is inserted into the assembly groove 13 and assembled, and when the rotating member 12 is rotated, the rotational force of the rotating member 12 is described above. It is transmitted to the operating member 20 through the 22, the rotating member 12 and the operating member 20 is rotated together.

In addition, the rotating member 12 and the operation member 20 are formed with engaging projections 14 and 24 engaged with each other.

When the engaging projections 14 and 24 are formed as described above to assemble the rotating member 12 and the operating member 20, the assembled state is maintained and movement in the longitudinal direction is suppressed.

A part of the outer circumferential surface of the rotating member 12 is formed with a handle 15 made of a plurality of grooves and / or projections so that the user can easily hold and rotate by hand.

In addition, the lower end of the rotating member 12 forms a lid assembly 16 to which the lid 40 is assembled, and the lid assembly 16 has a coupling protrusion of the lid 40. The engaging projection 17 to which 44 is engaged is formed.

When the lid assembly 16 is formed on the rotating member 12 as described above, the entire length can be formed long by assembling the lid 40 to the lid assembly 16 when writing. 40) It is very effective because there is no risk of losing it.

In the above, the rotating member 12 and the operating member 20 have been described as separately manufactured and assembled as separate components, but the present invention is not limited thereto, and the rotating member 12 and the operating member ( 20) can be formed integrally.

As shown in Figs. 1 and 2 and 9 and 10, the moving device 30 moves integrally with the screw member 32 having a male screw formed to a predetermined length and the screw member 32. And a support member 36 for supporting a portion of the solid ink 50 using elasticity.

The screw member 32 and the support member 36 may be formed integrally, but may be configured to be separately manufactured and assembled, although not shown in the drawing.

The inner surface of the operating member 20 of the rotating device 10 forms one or more operating protrusions 26 inserted into the screw grooves 33 of the screw member 32.

When the operating projection 26 is formed as described above and inserted into the screw groove 33 of the screw member 32 and the rotating device 10 is rotated, the operation projection 26 is the screw groove 33 It rotates along, and since the rotating device 10 is assembled in the state in which the longitudinal movement is restrained by the said outer cylinder 2, the said screw member 32 moves in the longitudinal direction.

The operating member 20 facilitates the coupling with the screw member 32, and after being coupled, a plurality of the plurality of operating projections 26 and the screw groove 33 to be in close contact by applying an elastic force. An elastic groove 28 is formed.

The operation protrusion 26 is positioned adjacent to the upper end of the screw member 32 in a state where the screw member 32 is inserted into the operating member 20 and the rotation member 12 as deeply as possible. It is preferable to form, since it reduces unnecessary space and can utilize the length of the said screw member 32 as efficiently as possible.

The length of the screw member 32 is formed to have a length corresponding to the length of the solid ink 50.

That is, in the state where the screw member 32, which is the first state, is inserted into the operating member 20 as deeply as possible, the upper end of the solid ink 50 is the other side of the outer cylinder 2 ( The operating protrusion 26 is caught by the upper end screw groove 33 of the screw member 32 in a state of protruding slightly from the upper end thereof, and the solid ink 50 is almost In the used state, the operating protrusion 26 is inserted into the screw groove 33 of the lower end of the screw member 32 in the state where the screw member 32 is inserted as shallowly as possible into the operating member 20. Configure to take.

In addition, the inner surface of the outer cylinder (2) is formed with a guide projection (5) in the longitudinal direction as shown in Figs. 3 and 9 to 10, and the outer surface of the support member 36 is shown in Figs. As shown in FIG. 12, guide grooves 34 are inserted into the guide protrusions 5.

When the guide projection 5 of the outer cylinder 2 is inserted into the guide groove 34 of the support member 36 by the above, the moving device 30 moves according to the rotation of the rotary device 10. When moving forward and backward constantly along the guide projection (5) without shaking.

The outer circumferential surface of the support member 36 is formed in the flexible portion 37 having a thin thickness so as to be stretched, and is formed integrally with the flexible portion 37 and is formed at predetermined intervals and has a large elastic force. It is composed of an elastic portion 38 formed thicker than the flexible portion 37.

The inner surface of the flexible portion 37 and the elastic portion 38 of the support member 36 is formed as an inclined surface gradually increasing from the end surface toward the bottom (bottom side) to support the solid ink 50 described above. It is preferable because the supporting force can be secured.

On the inner surface of the rotating member 12, assembling protrusions 18 are formed as shown in Fig. 5, and at one end of the outer cylinder 2, the assembling protrusions as shown in Figs. An assembly groove 6 into which the 18 is inserted is formed.

When the assembly protrusion 18 is inserted into the assembly groove 6 and configured as described above, the rotating member 12 is assembled to the outer cylinder 2 in a state in which only rotation is possible in a state in which movement in the longitudinal direction is restricted. do.

In addition, an outer surface of one end of the outer cylinder 2 is formed with an O-ring groove 7 for inserting the O-ring 9 as shown in FIGS. 1 and 9, and the rotation member 12 is As shown in Fig. 5, an inner surface forms an O-ring groove 19 into which the O-ring 9 is inserted.

Inserting the O-ring (9) as described above to prevent the intrusion of outside air in the state in which the outer cylinder (2) and the rotating member 12 is assembled.

The solid ink 50 is formed by microencapsulating and solidifying an ink composition obtained by mixing a solvent, a colorant, and a resin release agent using a film forming material.

Since the ink composition may use an ink composition which is generally used, detailed descriptions of materials and components will be omitted.

In addition, the ink composition can change the composition of a solvent (solid forming material) and the like for improving workability and solidifying.

Examples of the film forming material include polyamide, nylon, polyterephthalate, polyurethane, acrylic acid ester, polymethacrylic acid ester, polystyrene, divinylbenzene, polyisocyanate, polyol, polyamine, acid chloride, organic amine, acid amide, poly Acrylic acid, gelatin, starch, gum arabic, rosin, polyvinyl alcohol, polyvinylidene chloride, cellulose acetate, carboxymethyl cellulose, hydroxyethyl cellulose, polyvinyl chloride, acrylic resin, polyester, polyethylene, polypropylene, epoxy resin Select one or more from phenol resin, silicone resin, etc. and use it alone and / or mixed.

It is preferable to select and use the said film forming substance in the range of about 1-30 weight%, and about 5-10 weight% is more preferable.

It is preferable to perform the microencapsulation operation so that the average particle diameter of the microcapsules is in the range of approximately 0.1 to 5 μm.

If the average particle diameter of the microcapsules is less than 0.1㎛ in the above, it is difficult to manufacture, if larger than 5㎛ there are many difficulties in solidification due to the destruction of the capsule during the solidification operation.

And it is preferable to carry out the microencapsulation operation so that the film average thickness of the microcapsules is in the range of approximately 0.01 to 1 μm.

When the film average thickness of the microcapsules is less than 0.01㎛, the operation is difficult, and when larger than 1㎛, the breakage of the capsule due to friction at the time of writing does not occur smoothly, the writeability is reduced.

In the encapsulation (microcapsulation) method that performs the microcapsulation (microcapsulation) is a chemical method, a physicochemical method, a physical mechanical method and the like.

The interfacial polymerization method for preparing microcapsules using an interfacial polymerization reaction in which a monomer is dissolved in two solvents which are not mixed by the chemical method and the polymer is synthesized at the interface of the nutrient solution, and one of the two phases which do not mix with each other When the monomer and the catalyst are dissolved in the monomer, the monomer generates a polymerization reaction at the interface and a uniform film is formed on the surface of the core material. In situ polymerization method for preparing microcapsules and the material to be encapsulated are previously dispersed in the polymer solution. For example, there is an orifice coating method in which the solution is adjusted to a desired mold and the polymer is cured to form a film.

In the above-mentioned physicochemical method, when another substance (precipitant, etc.) is added to hydrophilic colloid (especially polymer solution) or the environment such as temperature is changed, colloid-rich liquid (disperse phase) and colloid-deficient liquid (continuous phase) Phase separation method using coacervation to separate the dog phase and forming microcapsules with coacervate, a colloid-rich phase (droplet), and a core in a solvent in which a film-forming material as a wall material is dissolved. In-liquid drying method to disperse a solution or solid consisting of an ink composition as a substance, gradually disperse it in a solvent which is not mixed with the solvent, and to remove the first solvent to precipitate at the interface of the core ink composition to form microcapsules. Solid wax, fat cells, polyethylene, etc. Melting dispersion cooling method and the like to be formed using the microcapsules.

The phase separation method can be divided into a phase separation method (simple coacervation and complex coacervation) from an aqueous solution system and a phase separation method (combination method of a good solvent and a poor solvent and a method using a temperature difference) from an organic solution system.

The physicomechanical method includes an air suspension coating method (Wurster method) that physically adsorbs a film forming material, which is a wall material, to form a microcapsule on the surface of an ink composition, which is a core material, and sprays it in hot air by dispersing fine droplets Spray drying method for forming microcapsules by drying method and spraying film forming material, which is a wall material, from the top while the particles are mixed by the rotation of the plate and the particles inside come to the surface. Plate coating method for uniformly applying a wall material to form microcapsules.

Among the various encapsulation methods described above, encapsulation can be easily performed by chemical method, solidification using solid-forming material, and encapsulation and solidification by spray drying method. It is preferable because it is simple.

The solid ink 50 may be formed by solidifying an ink composition obtained by mixing a solvent, a colorant, and a release agent by using a fatty acid salt as a solid forming material.

The fatty acid salts are mainly used fatty acid salts having a carbon number in the range of about 10 to 28.

Moreover, as fatty acid which comprises said fatty acid salt, lauric acid, palmitic acid, stearic acid, etc. can be used.

And as the alkali metal salt of fatty acid, lithium salt, sodium salt, potassium salt, ammonium salt, etc. can be used.

It is preferable to select the usage-amount of said fatty acid salt in the range of about 5-15 weight%, and the range of about 5-10 weight% is more preferable.

Generally as said coloring agent, all the coloring agents used for the erasing ink for writing boards can be used.

It is preferable to select the usage-amount of said coloring agent in about 0.1 to 15 weight% range, and about 4 to 10 weight% range is more preferable.

If the amount of the colorant used is less than 0.1% by weight, it is difficult to identify the writing line because the concentration is light. If the amount of the colorant is more than 15% by weight, the dispersibility and solubility of the colorant are lowered and the erasure of the writing line is lowered.

Fatty acid ester etc. can be used as said peeling agent.

Fatty acid esters used in the above release agents include mixed fatty acid triesters of trimethopropane lauric acid and stearic acid, trimestero propane capric acid triesters, trimethiropropane lauric acid triesters, isodecyl alcohol and isono Esters of nanoic acid may be used.

Said fatty acid ester uses the thing of the molecular weight about 100-500 range.

When the molecular weight of the fatty acid ester is less than 100, the erasing property is insufficient, and when the molecular weight is more than 500, the erasing property is improved, but the writing surface becomes rough at the time of writing, making uniform writing difficult.

In addition, the solid ink 50 uses fatty acids having a carbon number in the range of about 5 to about 15 to form a surface coating for drying prevention.

Next, the assembly process of the writing instrument for writing boards which concerns on this invention comprised as mentioned above is demonstrated.

First, in a state where the assembly protrusion 22 of the operating member 20 is inserted into the assembly groove 13 of the rotating member 12, the locking protrusions 14 and 24 are engaged with each other. The rotating member 12 and the operating member 20 are assembled to form the rotating device 10.

Subsequently, the operation projection 26 of the operation member 20 is inserted into the screw groove 33 of the screw member 32 of the moving device 30 to rotate the moving device 30. Assemble the screw member 32 to the operating member 20 as deep as possible.

And the rotating member 12 of the rotating device 10 to the outer cylinder (2) to insert the assembly protrusion 18 of the rotating member 12 into the assembly groove (6) of the outer cylinder (2). And between the operating member 20.

In the assembled state as described above, the high-temperature solid ink 50 which has not yet solidified is injected through the other (upper) open end of the outer cylinder 2.

At this time, when the solid ink 50 is injected at a predetermined pressure, the flexible portion 37 of the support member 36 of the moving device 30 is stretched to fill the solid ink 50.

And when the solid ink 50 is condensed while cooling and solidifying, the supporting member 36 is solidified while the elastic portion 38 returns to its original state (the diameter at the end thereof is smaller than the bottom). The lower end of the shape ink 50 is supported, and the solid ink 50 is condensed to form a rod shape having a diameter slightly smaller than that of the outer cylinder 2, so that the moving device 30 moves forward (lid ( The solid ink 50 also moves forward or backward as the 40 is assembled to the side where it is assembled) or backward (moving toward the rotating member 12).

In the state where the assembly is completed as described above, when storing without taking the writing, the lid 40 is assembled to the outer cylinder 2, when writing, the lid 40 is separated from the outer cylinder 2 and the It is used by assembling on one rotating member (12).

In the above, it has been described that the solid ink 50 is used in the writing instrument for writing board according to the present invention, but the present invention is not limited thereto, but instead of the solid ink 50 described above, paste, lipstick, crayon, colored pencil, etc. It is also possible to use a solid material.

In the above, a preferred embodiment of a writing instrument for writing board according to the present invention has been described, but the present invention is not limited thereto, and various modifications can be made within the scope of the claims and the detailed description of the invention and the accompanying drawings. This also belongs to the scope of the present invention.

According to the writing instrument for writing plate according to the present invention made as described above, since the solid ink is used, the writing is performed while the microcapsule or the surface coating is removed by friction with the writing plate during writing.

Even when writing is not performed, the ink composition is contained in the microcapsules or the surface coating is formed again so that the ink composition is not dried, so that even writing lines are always uniform, and writing is smooth and easy even when stored for a long time with the lid open. I can do it.

And since the solid ink is finely separated by microcapsules or fatty acid salts, some of the ink composition is prevented from sedimentation or separation, and writing lines of uniform quality can be always obtained.

In addition, since the support member of the moving device is composed of a flexible portion and an elastic portion to support the solid ink, it is easier to manufacture by a manufacturing method such as injection molding, and new support, as compared with a member for moving solids such as a paste. Provide a way.

Therefore, according to the present invention, it is possible to provide a writing instrument for a writing plate of a new and various design.

Claims (10)

An outer cylinder formed into a predetermined shape and having open ends at both ends in the longitudinal direction; A rotating device rotatably assembled at one end of the outer cylinder; A moving device inserted into the inside of the outer cylinder so as to be movable in the longitudinal direction and assembled to the rotating device to move forward or backward in the longitudinal direction of the outer cylinder as the rotary device rotates forward or reverse; A solid ink supported by the moving device and movably inserted into the outer cylinder, The rotating device is made to rotate integrally with the rotating member and the rotating member rotatably assembled at one end of the outer cylinder and is rotatably inserted into the inside of the outer cylinder and the moving device is inside It is composed of the operating member to be assembled, The moving device is a writing instrument for writing board consisting of a screw member is formed with a male screw to a predetermined length and the support member for supporting a portion of the solid ink using elasticity. The lid of claim 1, further comprising: a lid assembled at the other end of the outer cylinder, protecting the exposed portion of the solid ink from the outside, and forming a clip that can be inserted into a collar or a pocket collar on one side. Writing instrument for writing. delete According to claim 1, wherein the rotating member is formed at least one assembly groove in the longitudinal direction, At the lower end of the operating member to form one or more assembly protrusions to be fitted to the assembly groove, The rotating member and the operating member are formed to engage each other engaging projections, On the inner surface of the operating member to form one or more operating projections that are inserted into the screw groove of the screw member, On the inner surface of the outer cylinder is formed guide projections in the longitudinal direction, Writing instrument for writing plate on the outer surface of the support member to form a guide groove inserted into the guide projection. [5] The writing plate of claim 4, wherein the operating member facilitates the coupling with the screw member and, after being coupled, forms a plurality of elastic grooves to be in close contact with the operating protrusion and the screw groove by applying an elastic force. Writing utensils. According to claim 4, wherein the outer peripheral surface of the support member is formed integrally with the flexible portion formed in a thin thickness to enable the stretching and the flexible portion is formed at a predetermined interval and thicker than the flexible portion to retain the elastic force It is made of an elastic portion formed, The inner surface of the flexible portion and the elastic portion of the support member is a writing instrument for writing board to form an inclined surface gradually increasing from the end surface toward the bottom. The writing instrument of claim 4, wherein at least one assembly protrusion is formed on an inner surface of the rotating member, and at least one assembly groove is inserted on an outer surface of one end portion of the outer cylinder. The method of claim 1, wherein the solid ink is formed by microencapsulating and solidifying an ink composition obtained by mixing a solvent, a colorant, and a resin release agent using a film forming material, The solid ink described above is a writing instrument for writing board comprising the addition of a fatty acid having a range of 5 to 15 carbon atoms as a surface coating agent to the ink composition of a solvent, a coloring agent and a release agent and solidifying using a fatty acid salt as a solid forming material. The method of claim 8, wherein the film forming material is polyamide, nylon, polyterephthalate, polyurethane, acrylic acid ester, polymethacrylic acid ester, polystyrene, divinylbenzene, polyisocyanate, polyol, polyamine, acid chloride, organic Amine, acid amide, polyacrylic acid, gelatin, starch, gum arabic, rosin, polyvinyl alcohol, polyvinylidene chloride, cellulose acetate, carboxymethyl cellulose, hydroxyethyl cellulose, polyvinyl chloride, acrylic resin, polyester, polyethylene At least one selected from polypropylene, epoxy resin, phenol resin and silicone resin, Writing instrument for writing board used as the film-forming material is selected from the range of 1 to 30% by weight. 9. The fatty acid salt according to claim 8, wherein the fatty acid salt is selected from fatty acid salts having a carbon number of 10 to 28 carbon atoms in the range of 5 to 15% by weight, As the fatty acid constituting the fatty acid salt, one or more selected from lauric acid, palmitic acid and stearic acid is used. As said peeling agent, the mixed fatty acid triester of trimethiropropane lauric acid and stearic acid which is a fatty acid ester of the molecular weight of 100-500, a trimethylo propane capric acid triester, a trimethiropropane lauric acid triester, Writing instrument for writing board used by selecting one or more of esters of isodecyl alcohol and isononanoic acid.