JPH0630991B2 - Discolored core - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color-changing core having a feature that writing lines of other colors appear by erasing black writing lines with an eraser. The idea of changing the color of is completely new, and the gist is that there is a writing line of black powder on the paper,
The ink soaks into the paper surface, and the black powder on the paper surface is erased with an eraser, whereby the handwriting of the ink on the paper surface appears.

Conventionally, as a writing instrument, a solid writing instrument such as a pencil or a sharp pencil, and a liquid writing instrument using ink such as a fountain pen, a felt-tip pen, and a ballpoint pen are known. Each of these has its own characteristics.Broadly speaking, while the handwriting of the solid writing system of the former can be erased with an eraser, the handwriting of the latter ink cannot be erased even with an eraser. Then, by combining the solid writing material and the ink as in the present invention, the handwriting of the solid writing material is erased by an eraser,
I never thought of expressing the handwriting of ink and causing it to change color.

As a conventional example of impregnating a lead core with ink, Japanese Patent Publication No.
There is a method for producing a pencil lead for tracing, in which clay and carbon black are used as the main material such as -3194, and the clay and carbon black are additionally molded and burned to absorb and infiltrate the oil black dye and the ultrafine powder carbon black. The purpose is to further impregnate the black ink in the pores with black ink to further increase the black color of the handwriting, and not to obtain the discolored core by impregnating the colored ink into the black sintered body as in the present invention. .

In addition, there is a pencil lead, which is obtained by impregnating a rod-shaped porous fired body made of a mixture of refractory powder and a binder with ink, as in JP-B-49-34045.

Among them, the refractory powder is a white and slippery boron nitride powder or talc powder, and the binder is white clay such as bentonite, which is a rod-shaped mixture of the refractory powder and the binder. The porous fired body has a white hue,
It is a colored pencil core that is impregnated with ink to dye a white fired body to obtain an arbitrary hue, and the handwriting can be erased with an eraser. As in the present invention, the colored ink is absorbed on the paper surface. By removing the black powder above with an eraser,
It is different from the core that changes color from black handwriting to colored ink that cannot be erased with an eraser.

That is, the present invention is composed of a porous black sintered body using carbon as a binder and a colored ink excluding black filled in the pores of the porous black sintered body, the ink containing a wettable solvent as a main component, The present invention relates to a core comprising a dye soluble in the core.

The sintered body used in the present invention uses carbon as a binder, and the sintered body has a strong coloring power because the carbon is black. Further, this sintered body has pores that can be impregnated with a liquid, and the amount of ink filled in the pores of the sintered body is determined by the proportion of the pores (porosity).

The porosity of this black sintered body is preferably in the range of 20 to 70%. If the porosity is less than 20%, the amount of ink filled in the black sintered body is too small, and even if various examinations are performed on the filled ink, the color of the colored ink is extremely weak and functions as a color change core. do not do.

Further, when the porosity exceeds 70%, the sintered body is fragile because it has too many pores and is easily broken when used as a core of a solid writing material.

In the present invention, the porosity is measured by absorbing a liquid having good permeability (for example, benzyl alcohol) into the pores of the lead core, dividing the volume of the absorbed liquid by the bulk volume of the lead core, and expressing it as a percentage. is there.

However, W ₁ is the dry weight of the lead core before absorbing the liquid.

W ₂ is the weight of the lead core in which the liquid is absorbed in the pores in the liquid.

W ₃ is the weight of the lead core after the liquid is absorbed in the pores of the lead core.

The ink used in the present invention preferably contains a wettable solvent as a main component and a dye soluble in the wettable solvent, and preferably has a dye concentration of 15% or more.

That is, in a liquid writing instrument such as a normal fountain pen or a felt-tip pen, even if the ink has a dye concentration of 5% or less, a clear handwriting can be obtained by sufficiently supplying the ink from the ink tank. As described above, the core of the invention has a limited amount of ink to be filled in the sintered body, and does not function as a color-changing core unless color is developed with the amount of ink inherent in the amount of wear when the solid writing body is written.

That is, as a result of earnest studies to obtain sufficient color development with a small amount of ink, it was found that good results can be obtained when the dye concentration of the ink is 15% or more and the solvent of the dye has wettability.

Increasing the concentration of the dye, which is the source of the coloring power of the ink, is a necessary condition for obtaining a strongly colored ink, but increasing the dye concentration alone increases the viscosity of the ink because the amount of solvent is insufficient. In addition, the adhesiveness with the solid writing material is increased to prevent the transfer of ink from the handwriting to the paper surface, and conversely, the effect as a discoloration core is diminished.

For this reason, the inventor has set the dye concentration in the solid writing body to 15
% We selected one that has a wettability to the solvent while keeping it above 100%, and devised to supplement the moisture from the paper or the air after writing,
As a result, an ink having a satisfactory color change core was obtained.

Although this effect is not clear, the written paper is a layer of plant fibers entangled with water, and the binding force of the plant fibers is said to be due to water binding, usually 4 to 5%. Contains water.

Since the ink of the present invention uses a wettable solvent, the water contained in the paper and the ink contained in the handwriting can be smoothly transferred to each other, and the water is replenished from the air to make the handwriting. On the other hand, it is considered that the coloring of a good colored ink was obtained with a sufficient ink amount.

As the wettable solvent used here, ethylene glycol, diethylene glycol, triethylene glycol,
Glycerin such as propylene glycol and polyethylene glycol and glycerin are preferable because they have high hygroscopicity, and glycols such as ethylene glycol ethyl ether, ethylene glycol phenyl ether, ethylene glycol benzyl ether, triethylene glycol phenyl ether, and triethylene glycol benzyl ether. Ethers are inferior in hygroscopicity to glycols, but may be partially added as a wettable solvent.

Further, among the wettable solvents, an ink having a boiling point of 200 ° C. or higher is preferable because the color-changing core has excellent stability over time.

On the other hand, the dye used in the colored ink may be any dye that is soluble in the above-mentioned wetting solvent, but especially the basic dye is excellent in coloring power, and the water-soluble dye and the alcohol-soluble dye are written with a discoloring core. It is preferable because it is excellent in the transfer power from the written handwriting to the paper surface.

Next, the manufacturing method of the discolored core of the present invention will be briefly described. Lubricant such as graphite or boron nitride, and an organic compound that is carbonized by firing are melted or melted by heating with any solvent, kneading using a three-roll or kneader, extrusion molding, then inert 1000 ° C in gas
It is fired at a high temperature before and after to carbonize the organic compound to obtain a porous black sintered body composed of a lubricant and a carbon binder.

As the organic compound used here, natural resin, synthetic resin, asphalt, coal tar pitch or the like may be used alone or in combination.

On the other hand, in the preparation of the colored ink, a dye which is soluble in the wetting solvent and has a desired hue is added and stirred, and in some cases heated to dissolve.

The porous black sintered body is dipped in this colored ink for a certain period of time, and the colored ink is filled in the pores of the porous black sintered body to form a color-changing core.

Next, examples of the present invention will be described. (Parts are parts by weight.) [Example 1] 50 parts of graphite and 5 of blown asphalt # 20 to 30 were used.
0 parts are kneaded by heating, extrusion-molded, then heated in an inert gas from room temperature to 1100 ° C. at 100 ° C./hr, and 110
The porous black sintered body composed of graphite and carbon was obtained by firing at 0 ° C. for 1 hour. The porosity of this porous black sintered body was 32%.

On the other hand, the color ink was prepared by adding 20 parts of SWT-R4 (manufactured by Hodogaya Chemical Industry Co., Ltd.), which is a basic dye, to 80 parts of triethylene glycol and thoroughly stirring to dissolve it to obtain a wet red ink. It was

The porous black sintered body was dipped in the wet red ink for 3 hours, and the wet red ink was filled in the pores of the porous black sintered body to obtain a discolored core.

Example 2 To 60 parts of triethylene glycol and 20 parts of ethylene glycol phenyl ether, 20 parts of rhodamine base FB (manufactured by BASF), which is a salt-dissolving salt-forming dye, was added.
It was well stirred and dissolved to obtain a wet pink ink.

The same porous black sinter as in Example 1 was immersed in this wet pink ink for 2 hours to fill the pores of the porous black sinter with the wet pink ink. And made it a discolored core.

[Example 3] 55 parts of propylene glycol and 30 parts of ethylene glycol benzyl ether were added to SWT-B which is a basic dye.
15 parts of 5 (manufactured by Hodogaya Chemical Co., Ltd.) were added and dissolved by stirring well to obtain a wet blue ink.

The same porous black sinter as in Example 1 was dipped in this wet blue ink for 3 hours to fill the pores of the porous black sinter with the wet blue ink to form a discolored core. did.

[Comparative Example 1] As an example of a water-based ink used for a fountain pen, a felt-tip pen, etc., 80 parts of water, 5 parts of glycerin and 5 parts of ethylene glycol were used.
5 parts of SWT-R4 (manufactured by Hodogaya Chemical Industry Co., Ltd.), which is a basic dye, was added to a mixed solvent of 5 parts of diethylene glycol and 5 parts of diethylene glycol, and well mixed by stirring to obtain an aqueous red ink.

The same porous black sinter as in Example 1 was immersed in this aqueous red ink for 3 hours to fill the pores of the porous black sinter with the aqueous red ink.

[Comparative Example 2] As an example of an oil-based ink used for a ball-point pen, a rhodamine base FB (BASF Corp.), which is a salt-forming dye that is soluble in alcohol, is used in a mixed solvent of 30 parts of benzyl alcohol, 5 parts of oleic acid and 25 parts of phenyl glycol. 25 parts),
The mixture was thoroughly stirred and dissolved, and 10 parts of a ketone resin and 5 parts of a polyvinylpyrrolidone resin were further added to obtain an oily pink ink.

This oily pink ink was heated to 60 ° C., and the same porous black sintered body as in Example 1 was immersed in this ink to 100 mm.
The pressure was reduced to Hg and the mixture was allowed to stand for 1 hour to fill the pores of the porous black sintered body with an oily pink ink.

When the discolored cores of Examples 1, 2, and 3 and the cores of Comparative Examples 1 and 2 were written on a note paper, the following results were obtained.

The discolored core of Example 1 is a normal black handwriting immediately after writing, and when the handwriting is erased with an eraser, a slightly reddish handwriting remains,
It can be almost erased.

After about 5 minutes, if you erase the black handwriting with an eraser, you can confirm the transfer of the red ink to the paper surface.

The transfer of the ink to the paper is slightly different depending on the humidity at that time, but the transfer begins within a few minutes and the color of the ink gradually becomes stronger,
When the black handwriting was erased with an eraser, a clear red handwriting remained, functioning as a discoloration core.

The discolored core of Example 2 was slower in transferring the ink onto the paper than the discolored core of Example 1, but a dark pink handwriting was obtained by erasing the black handwriting after about 2-3 days with an eraser. The rest functioned as a tarnish core.

In the color-changing core of Example 3, the ink was transferred to the paper at a speed substantially similar to that in Example 1, and when the written black handwriting was erased with an eraser, a clear blue handwriting remained and functioned as a color-changing core.

The handwriting written with the core of Comparative Example 1 is sufficient as a black handwriting, but if it is erased with an eraser, a slightly red handwriting remains, and this color tone is not improved over time, and discoloration occurs. It was insufficient as a core. Further, this core was evaporated because the main component of the ink in the pores of the black sintered body was water, and the ink was scattered very rapidly immediately after the ink was filled, and it was not practical to blink. .

The handwriting written with the core of Comparative Example 2 remained completely black and could be completely erased by erasing with an eraser. This is the same over time, and the handwriting is no different from the usual black core that can always be erased with an eraser.

As described above, by erasing a black writing line with an eraser, a color-changing core having a characteristic that writing lines of other colors appear, which is realized within the scope of the claims,
The combination of the constitutions is a novel constitution for embodying the effect of the present invention, and therefore, a lead core having a unique characteristic having an effect which has never been obtained is obtained. This is an epoch-making effect that cannot be obtained with a lead core impregnated with ordinary ink.

As described above, the lead core of the present invention is considered to have various applications due to its unique effect.For example, by erasing an important portion written with a black handwriting, a colored writing line is realized, It has a great industrial effect such that the contents can be compared and examined.

Claims (3)

[Claims] 1. A porous black sintered body containing carbon as a binder and a colored ink excluding black filled in the pores of the porous black sintered body, the ink containing a wettable solvent as a main component. And a solubilized dye in the wick. 2. The porosity of the porous black sintered body is 20 to 70%.
The core according to claim 1, wherein 3. The core according to claim 1, wherein the dye density of the ink filled in the pores is 15% or more.