JP7803519B2 - solid ink - Google Patents

Description

The present invention relates to solid ink.

Conventionally, for example, solid ink containing soot and glue has been known.

This type of solid ink is used by grinding it on an inkstone and mixing it with water. The ink is then applied to paper using a brush or similar device containing the ink mixture, allowing letters or pictures to be drawn.

Conventional solid ink is produced over a period of several months, for example, as follows: an aqueous solution containing glue is mixed with soot powder to create an intermediate mixture, which is then molded into the desired shape in a mold, and then dried at room temperature to produce solid ink.
Conventional ink sticks produced in this way are ground on an inkstone to form liquid ink, which is then used in applications such as calligraphy and ink painting. By applying ink sticks prepared so that the solids concentration of the ink stick is low to paper, a lighter black color can be achieved. Furthermore, because the ink sticks contain a high amount of water, they tend to bleed, allowing for unique expressions in writing and painting.

There are various types of solid ink sticks, ranging from inexpensive ones to high-end products used by calligraphers, and some high-end products are produced through a long drying process.
In response to this, for example, solid ink sticks having through holes or recessed holes formed on the surface are known (see Patent Document 1).
The solid ink described in Patent Document 1 is produced by forming holes as described above in an intermediate mixture of soot and glue, followed by a drying process. The solid ink described in Patent Document 1 can be produced in a relatively short drying time because the surface area is increased by the formed holes. The solid ink described in Patent Document 1 produced in this way can express colors and bleeding similar to those of letters and pictures drawn using the above-mentioned conventional solid ink.

Japanese Patent Application Laid-Open No. 2004-035664

However, for certain applications, such as painting, there is a demand for ink liquid prepared using solid ink that can express gray while suppressing bleeding. With the conventional solid ink liquids described above, ink liquids with a high solid content in the solid ink to suppress bleeding can only express black, while ink liquids with a low solid content in the solid ink simply produce a lighter black and cannot express gray, and cannot suppress bleeding. Solid ink liquids that contain carbon black instead of soot are known, but a solid ink liquid that can express gray has not yet been discovered, and has not yet been fully investigated.

The objective of this invention is to provide solid ink that can express gray.

The solid ink of the present invention contains particulate graphite and glue.

In the solid ink, the particle size of the graphite may be in the range of 1 μm or more and 50 μm or less.
In the solid ink, the graphite may contain at least flake graphite.

The solid ink of this invention can express gray tones that could not be achieved with conventional solid ink, while suppressing bleeding.

1 is a photograph of an image of a diluted ink solution prepared using the solid ink of this embodiment, observed under an optical microscope. Photographs of lines drawn with ink liquids prepared using each solid ink of the Examples and Comparative Examples. Photographs of lines drawn with ink liquids prepared using each solid ink of the Examples and Comparative Examples.

One embodiment of the solid ink according to the present invention is described below.

The solid ink of this embodiment contains particulate graphite and glue. With this configuration, the solid ink of this embodiment can express gray and suppress bleeding.
More specifically, a portion of the solid ink in this embodiment is contained in ink liquid prepared by grinding the ink together with water on an inkstone, for example. When the prepared ink liquid is applied to paper or the like using a brush tip or the like, it is possible to express gray colors while suppressing bleeding. In particular, by preparing the ink liquid so that the concentration of the solid ink is higher, it is possible to express gray colors while further suppressing bleeding.
On the other hand, when conventional solid ink sticks, which mainly contain soot or carbon black as carbon particles, are ground to a relatively low concentration in the ink solution, they can produce a light black color similar to gray, but it is not gray at all and they end up bleeding.On the other hand, when the solid ink sticks are ground to a relatively high concentration in the ink solution, bleeding is prevented but a deep black color is produced and gray cannot be produced.

In this embodiment, the solid ink contains water. The water content of the solid ink is, for example, 12% by mass or less. The water content of the solid ink may be, for example, 5% by mass or more and 12% by mass or less.

The type of graphite is not particularly limited. Examples of graphite include artificial graphite and natural graphite. Examples of natural graphite include amorphous graphite, scaly graphite, flake graphite, and expanded graphite.
As the graphite, commercially available products can be used, such as products manufactured by Ito Graphite Industries Co., Ltd. or Chuetsu Graphite Industries Co., Ltd.

As graphite, at least one of flake graphite, artificial graphite, and earthy graphite is preferred, with flake graphite being more preferred. By using such preferred graphite, lines drawn with the tip of a brush using ink with a significantly lower solids concentration can express unique shades. More specifically, the boundary between the baseline drawn by the brush tip and the area outside the baseline (the area that bleeds) becomes clearer. The ability to draw lines with this appearance is sometimes referred to as beauty.

Each graphite particle is generally plate-shaped. The particle size of the graphite may be in the range of 1 μm to 50 μm. "Within this range" means that the particle size of at least 10 particles is measured by observing the dispersion in water, obtained by completely dissolving the glue in the solid ink, under a microscope, and the median value is in the range of 1 μm to 50 μm. The microscope may be an optical microscope or an electron microscope. The particle size is determined by measuring the longest diameter of each particle observed.

The particle size of the graphite is preferably in the range of 1 μm to 10 μm. This has the advantage of more reliably expressing the gray color and also improving the aesthetic quality mentioned above.

In this embodiment, the proportion of graphite among the carbon particles (black pigments) contained in the solid ink is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 99% by mass or more. In other words, it is particularly preferable that the total amount of soot and carbon black among the carbon particles contained in the solid ink is less than 1% by mass. It is particularly preferable that the solid ink of this embodiment contains almost no soot or carbon black. Most preferably, the solid ink of this embodiment contains only graphite as carbon particles.

The glue is a material containing protein extracted from animal skin, bones, tendons, etc. Examples of the animals include mammals, birds, and fish. Examples of mammals include cows, deer, horses, and rabbits. The glue contains, as a protein, for example, collagen-derived gelatin.
As the glue, commercially available products can be used.

As for the glue mentioned above, glue obtained from cowhide is preferred, as it is a commonly used raw material and is therefore readily available.

In the solid ink of this embodiment, most of the components other than graphite are glue. When the solid ink of this embodiment is ground with water on an inkstone, for example, and the ink solution is mixed so that the solids concentration is quite low, a unique bleeding effect can be achieved by applying the prepared ink solution to paper or the like using the tip of a brush. Specifically, the boundary between the baseline where the brush tip passes and the area outside the baseline (the bleeding area) becomes clear, allowing for the drawing of beautiful lines. This performance is thought to be influenced by the size distribution of the graphite particle aggregates in the ink solution, which will be described in more detail below.

In addition to glue, the solid ink of this embodiment may contain polyvinyl alcohol to improve the dispersibility of the particulate graphite. Preferably, the polyvinyl alcohol content is less than 1% by mass. In other words, it is preferable that the solid ink of this embodiment contains almost no dispersant such as polyvinyl alcohol. More preferably, the solid ink of this embodiment does not contain polyvinyl alcohol.
Compared to polyvinyl alcohol, glue provides greater transparency when ink is applied to paper and more soluble in water. It also offers a good balance of several properties, including the following: For example, when mounting calligraphy pieces for hanging scrolls, folding screens, partitions, or picture frames, glue can be used to attach mounting paper to the back of the piece, ensuring a smooth, clean finish without rippling. Furthermore, glue can moderately gel the solid ink intermediate during production, thereby providing good moldability, allowing it to be relatively easily cast into a mold.

Unlike solid ink, ink juice is known that can be used without preparation. Ink juice is a liquid in which carbon particles such as carbon black are dispersed in water, mainly by polyvinyl alcohol. Therefore, in ink juice, the polyvinyl alcohol allows the carbon particles to be dispersed without clumping together.
For example, if you draw a line with a brush using India ink diluted with water to create a bleeding effect, it is difficult to achieve a good bleeding effect. Specifically, the baseline where the brush tip passes and the area outside the baseline (the bleeding area) will have the same darkness, resulting in a line that is not very aesthetically pleasing. This is thought to be because the carbon particles disperse in the India ink without agglomerating much, and there is little variation in the size distribution of the carbon particle aggregates.

In the solid ink of this embodiment, the amount of glue may be 50 parts by mass or more and 70 parts by mass or less per 100 parts by mass of graphite (assuming the amount of graphite is 100 parts by mass).

The solid ink of this embodiment contains particulate graphite and glue, so it can express gray colors while suppressing bleeding, as described above. In particular, by increasing the solid content concentration of the solid ink in the ink liquid, it is possible to express gray colors while further suppressing bleeding.
Furthermore, when the solid content concentration in the ink liquid prepared with the solid ink of this embodiment is quite low, a unique bleeding effect can be expressed, and excellent beauty can be achieved. Specifically, the boundary between the base line passed by the brush tip containing the ink liquid and the area outside the base line (the bleeding area) becomes clear, allowing for the drawing of a highly beautiful line.
Furthermore, the solid ink of this embodiment allows the solids concentration of the ink liquid to be adjusted as needed. Specifically, even if the ink liquid is initially prepared on the inkstone so that the solids concentration is low, the solids concentration of the ink liquid can be increased by further stirring the solid ink on the inkstone. Conversely, the solids concentration can also be decreased by diluting the ink liquid with water. Therefore, it is relatively easy to both express gray lines with ink liquid having a high solids concentration and express beautiful lines with ink liquid having a low solids concentration.

The shape of the solid ink in this embodiment is, for example, a rectangular parallelepiped. In addition to the above-mentioned components, the solid ink in this embodiment may further contain preservatives, fragrances, etc.

The solid ink of this embodiment is produced, for example, as follows.
Specifically, particulate graphite is first mixed with an aqueous solution of glue. Mixing can be carried out using a general agitator/mixer. Water may be added to give the mixture (hereinafter referred to as the intermediate product of solid ink) an appropriate hardness.
Next, the solid ink intermediate is further kneaded on a board, and then stretched into a rod shape. The rod-shaped solid ink intermediate is placed inside a mold and shaped. The shaped solid ink intermediate is removed from the mold and subjected to a drying process. Specifically, in the drying process, the solid ink intermediate removed from the mold is sandwiched between newspaper and then buried together with the newspaper in wood ash, and the solid ink gradually dries in the wood ash, for example for 14 days. It is then dried in the air. The temperature and duration of the drying process can be adjusted as appropriate.
In this manner, the solid ink of this embodiment can be manufactured.

The solid ink of this embodiment is used, for example, by grinding it with water on an inkstone to form a component of ink liquid. Such ink liquid can be used to write characters on paper. Furthermore, for example, the ink liquid may be mixed with colored pigments, and the solid ink of this embodiment may be used to draw colored characters or pictures.

The object onto which the ink liquid containing the solid components of the solid ink of this embodiment is applied is not particularly limited, but may be, for example, a support (object to be drawn) on whose surface letters or pictures are to be drawn. The surface of the support may be either three-dimensional or flat. Examples of the support include paper. The type of paper is not particularly limited, but examples include calligraphy paper such as calligraphy paper or gasenshi paper, copy paper, synthetic paper (Yupo paper), and cotton paper.
The tool used to apply ink to the object to be applied is not particularly limited, but may be, for example, a brush.

Next, the present invention will be explained in more detail using examples, but the present invention is not limited to these.

Several solid ink sticks were produced using the following raw materials. Each of these solid ink sticks was ground with 0.6g of water on an inkstone for 3 minutes to prepare ink liquid. Lines were drawn on paper with the tip of a brush soaked in the ink liquid, and the performance of each was evaluated. Representative examples of the evaluation results are shown below.

<Ingredients for solid ink>
[Granular graphite]
- Flake graphite, product name "Z-5F" manufactured by Ito Graphite Industries, average particle size 4.0 μm
Product name: "W-5" manufactured by Ito Graphite Industries Co., Ltd. Average particle size: 4.0 μm
Artificial graphite, product name "ABG-5" manufactured by Ito Graphite Industries, average particle size 5.0 μm
Amorphous graphite, product name "CP-2000" manufactured by Ito Graphite Industries, average particle size 4.5 μm
Product name: "APR" manufactured by Chuetsu Graphite Industries Co., Ltd. Average particle size: 25 μm
[glue]
Product name: "Harima-2 (TS-201)" manufactured by Terawaki Sangyo Co., Ltd., or
Product name: "Asuka" manufactured by Kyokuyo Chemical Industry Co., Ltd.

<Dispersibility of graphite particles in diluted ink>
The prepared ink solution was diluted 50 times with water, and the diluted solution was observed under an optical microscope. Regardless of the graphite used, larger and smaller aggregates were mixed, and a relatively large difference in size between the two was observed. As a representative example, Figure 1 shows a microscope image when the above-mentioned "Z-5F" was used as the graphite and the above-mentioned "Harima-2 (TS-201)" was used as the glue.

The presence of aggregates of various sizes in the ink liquid is thought to be related to the aesthetic quality mentioned above. The presence of large aggregates mixed in is thought to enhance aesthetic quality, rather than the presence of only small aggregates. In other words, when a line is drawn with a brush tip containing ink with a low solids concentration, the greater the variation in the size of the aggregates in the ink liquid, the clearer the boundary between the baseline passed by the brush tip and the area outside the baseline (the area that bleeds).
It is believed that ink liquid containing a mixture of aggregates of different sizes as described above can be prepared by using solid ink made with glue rather than polyvinyl alcohol. Therefore, ink liquid prepared from solid ink containing graphite and glue is believed to be able to achieve the beauty shown in Figure 3(a) below.

<Appearance of lines drawn with ink (ink color and bleeding)>
Lines were drawn with a brush tip containing ink liquid (ink liquid with a relatively high solids concentration) prepared using solid ink made from the above-mentioned "Z-5F" as graphite and the above-mentioned "Harima-2 (TS-201)" as glue. Copy paper was used as the paper (see Figure 2(a)).
In addition, lines were drawn with a brush tip containing ink liquid (ink liquid with a fairly low solid content concentration) prepared using solid ink made from the above-mentioned "ABG-5" as graphite and the above-mentioned "Harima-2 (TS-201)" as glue. The paper used was gashi paper (see Figure 3(a)).
As a comparative example, a line was drawn in the same manner as above using a brush tip containing ink liquid prepared using conventional solid ink that does not contain graphite (see Figures 2 and 3(b)).

Lines drawn with ink liquid prepared to have a relatively high solids concentration using solid ink containing graphite particles and glue were gray with almost no bleeding. By grinding the solid ink of the example so that the solids concentration of the solid ink in the ink liquid was relatively high, bleeding was suppressed and a gray color could be expressed (see Figure 2(a)).
In addition, by increasing the solid content of the solid ink in the ink solution, bleeding could be more sufficiently suppressed.
On the other hand, even when lines were drawn using ink with a significantly lower solids concentration, it was possible to achieve beautiful lines and create unique expressions (see Figure 3(a)).

The solid ink of the present invention is used, for example, by being rubbed on an inkstone to form an ingredient in ink liquid for the purpose of writing letters or drawing pictures on paper.
Furthermore, the solid ink of the present invention can be used, for example, in the preparation of ink liquid as described above, and then further combined with a coloring pigment or a coloring dye. Specifically, a coloring composition prepared by mixing the ink liquid with a coloring pigment or a coloring dye can be used to express unprecedented colors in paintings, etc.

Claims (3)

A solid ink containing particulate graphite and glue,
The solid ink contains carbon particles in which the graphite accounts for 80 mass % or more . The solid ink described in claim 1, wherein the particle diameter of the graphite is in the range of 1 μm to 50 μm. The solid ink according to claim 1 or 2, wherein the graphite contains at least flake graphite.