India ink-like composition, writing instrument, and writing instrument set

Abstract

To provide an India ink-like composition having low environmental load and enabling erasing or fading of stains through washing.SOLUTION: An India ink-like composition comprises a humic substance, the solid content concentration of the humic substance preferably being 3 mass% or more, and the humic substance preferably being one or more selected from the group consisting of fulvic acid, humic acid, and humin.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an ink-like composition, a writing instrument, and a writing instrument set. [Background technology]

[0002] India ink is commonly used in calligraphy and painting, but when it splashes onto clothing made of fibers such as wool, cotton, rayon, polyester, and nylon, it can be difficult to remove even after washing.

[0003] In particular, when doing calligraphy at school, children would get their clothes dirty, so there were restrictions such as wearing gym clothes on calligraphy days or dark-colored clothes that would not show dirt.

[0004] Furthermore, due to these circumstances, people are increasingly turning away from calligraphy. Calligraphy and painting are important parts of Japanese culture, and are a traditional culture that should be preserved in the future. In order to preserve the culture of calligraphy and painting, there is a need for the development of an ink-like composition that allows calligraphy to be practiced without worrying about getting dirty.

[0005] India ink-like compositions that make stains easy to remove by washing have been proposed. Patent Documents 1 to 5 exemplify India ink-like compositions that inhibit dyeing of fibers including wool, cotton, rayon, polyester, nylon, etc., and enable stains to be erased or lightened by washing. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-263562 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-263563 [Patent Document 3] Japanese Patent Application Laid-Open No. 2010-024287 [Patent Document 4] Japanese Patent Application Laid-Open No. 2010-083936 [Patent Document 5] Japanese Patent Application Laid-Open No. 2010-083937 Summary of the Invention [Problem to be solved by the invention]

[0007] However, these ink-like compositions have the problem that writing and drawing on Japanese calligraphy paper disappear. Furthermore, they are primarily made of acid dyes and contain aromatic amines, water-soluble organic solvents, etc., which are not necessarily desirable from an environmental perspective. Furthermore, most of these proposals control color development by changing the pH. That is, they develop color in alkaline conditions and fade in acidic conditions. Therefore, they do not fundamentally solve the problem of component adhesion.

[0008] Furthermore, in recent years, with the rise in environmental awareness, there has been a demand for the development of products with a low environmental impact. There has also been a demand for ink-like compositions that inhibit dyeing of fibers including wool, cotton, rayon, polyester, nylon, etc., and enable stains to be erased or lightened by washing, while also having a low environmental impact.

[0009] However, no ink-like composition has been developed that allows calligraphy and painting to be enjoyed in the same way as ink, fundamentally eliminates adhesion of ingredients, and enables stains to be erased or lightened by washing.

[0010] In view of the above, an object of the present invention is to provide an ink-like composition that can erase or lighten stains by washing and that has a small environmental impact. [Means for solving the problem]

[0011] The present inventors have conducted extensive research to achieve the above object and have found that the above problems can be solved by an ink-like composition containing humic substances. The present invention is based on the above findings and is summarized as follows.

[0012] [1] An ink-like composition containing humic substances. [2] The ink-like composition according to [1], wherein the solids concentration of the humic substances is 3% by mass or more. [3] The ink-like composition according to [1] or [2], wherein the humic substance is one or more selected from the group consisting of fulvic acid, humic acid, and humin. [4] The ink-like composition according to any one of [1] to [3], which has a pH of 2 to 8. [5] The ink-like composition according to any one of [1] to [4], wherein the humic substance has a weight-average molecular weight of 500 or more. [6] The ink-like composition according to any one of [1] to [5], wherein the melanic index of the humic substance is 4 or less. [7] A writing implement having a barrel having a pen tip at one end and a storage section containing the ink-like composition according to any one of [1] to [6]. [8] A writing implement set comprising a writing implement and an ink-like composition container containing the ink-like composition according to any one of [1] to [6]. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide an ink-like composition that makes it possible to erase or lighten stains by washing, while at the same time having a low environmental impact. DETAILED DESCRIPTION OF THE INVENTION

[0014] An ink-like composition according to one embodiment of the present invention (this embodiment) will be described below.

[0015] [Ink-like composition] The ink-like composition according to this embodiment contains humic substances, and is specifically an ink-like composition used in calligraphy and painting.

[0016] India ink is made up of ingredients such as a black pigment called carbon black and adhesives. This black pigment is insoluble in both water and oil, making it difficult to remove completely, even at home or at a dry cleaner. Furthermore, carbon black has fine particles that easily get into the gaps between fibers, making it a typical example of stains that are very difficult to remove.

[0017] On the other hand, the ink-like composition of the present invention is mainly composed of humic substances and can be washed away or the color can be lightened. The ink-like composition is a colored liquid that preferably does not contain carbon black or glue and can be suitably used for calligraphy or ink painting.

[0018] In this embodiment, humic substances are a general term for "organic matter with an unspecified chemical structure (non-biological organic matter)" that is produced when biological organic matter is decomposed by microbial and chemical action after the death of an organism. Humic substances are generally broadly classified into three types: "humic acid," "fulvic acid," and "humin," based on their solubility in alkali and acid. Humic acid is defined as a component that is soluble in alkali but insoluble in acid, fulvic acid as a component that is soluble in both alkali and acid, and humin as a component that is insoluble in both alkali and acid.

[0019] Humic substances exist in nature and in soil. The black to brown color of soil is due to the presence of humic substances. Humic substances are also contained in skin care products and health foods and are known to have no adverse effects on the human body. Furthermore, they are known to be the main components of fertilizer products and biostimulant products, so they have no adverse effects on the environment or plants. In other words, an ink-like composition with a low environmental impact can be produced.

[0020] Humic substances are commercially available as industrialized products in solid or liquid form, but in the present invention, since the purpose is to use it as an ink-like composition, it is desirable to apply a liquid product from the viewpoint of being able to be painted or sprayed.

[0021] The concentration of the humic substance in the ink-like composition is not particularly limited, but the solids concentration of the humic substance is preferably 3% by mass or more, and more preferably 5 to 20% by mass. A solids concentration of 3% by mass or more allows the printing effect (any of color, persistence, or visibility) to be fully exhibited. Although some commercially available humic substances have a high solids concentration, they can also be diluted with water, alcohols, glycols, etc. to a solids concentration of 3% by mass or more.

[0022] In this embodiment, the humic substance is not particularly limited, and is preferably one or more selected from the group consisting of fulvic acid, humic acid, and humin. Generally, fulvic acid has a small molecular weight, and when it is used as the main component, the color when printed on paper is yellowish brown. Humic acid has a larger molecular weight than fulvic acid, and when an ink-like composition based on it is printed on paper, the color is dark brown.

[0023] The pH of the ink-like composition is preferably 2 to 8, and more preferably 3 to 7. A pH of 2 to 8 ensures safety. The pH can be adjusted to a desired range by adding an acid or alkali, for example. The pH can be measured by the method described in the Examples.

[0024] The weight-average molecular weight of the humic substance is preferably 500 or more, and more preferably 500 to 5,000. A weight-average molecular weight of 500 or more improves visibility and enables stains to be erased or lightened by washing. The weight-average molecular weight can be measured by the method described in the Examples.

[0025] From the viewpoint of improving visibility and erasing or fading stains by washing, the melanic index (MI) of the humic substances is preferably 4 or less, and more preferably 1.4 to 4.0.

[0026] Here, MI is an index used to classify soil humic acid, and is the ratio of absorbance at wavelengths of 450 nm and 520 nm (A450 / A520) in the absorption spectrum of a sodium hydroxide extract (Kyōichi Kumada, Chemistry of Soil Organic Matter, 2nd ed., Academic Press Center (1981), Japanese Journal of Soil Science and Plant Nutrition, Vol. 71, No. 1, pp. 82-85 (2000)). Specifically, it can be measured by the method described in the Examples.

[0027] The MI can be adjusted by increasing or decreasing the amount of nitric acid during the production of crude humic acid; increasing the amount of nitric acid increases the MI. It has also been found that an MI of 2.4 or higher improves the molecular weight and solubility of humic substances. Therefore, by taking the MI into consideration, it is possible to evaluate the physical properties of humic substances without performing complex analytical procedures such as measuring the weight-average molecular weight of the humic substances, and a humic acid extract suitable for this embodiment can be obtained.

[0028] The ink-like composition according to this embodiment is preferably enclosed in a package that can hold a predetermined amount. Specific examples thereof include a plastic container, or a writing pen.

[0029] The ink-like composition of this embodiment provides a long-lasting color when applied to paper for painting and writing, but when it adheres to clothing, the color can be removed or lightened by washing.

[0030] When washing clothes, it is recommended to soak them in warm water with bleach and detergent, then wash them as usual. This process can be repeated even once to significantly reduce the color, but the effect will be even greater if you repeat this process. Also, the reason why humic acid is resistant to ultraviolet rays is not clear, but the following reasons are thought to be the cause. UV-B (wavelength 280-315nm) and UV-C (wavelength 200-280nm) are known to affect the decomposition of organic matter, but it is possible that the binding energy of humic acid molecules is greater than the energy of these wavelengths. Also, UV-C with a wavelength of 254nm is known to generate ozone and decompose organic pollutants, but because humic acid is resistant to ozone, it is thought that it can prevent fading from ultraviolet rays.

[0031] After application of the ink-like composition of this embodiment to a substrate (paper or textile), the substrate appears dark brown to brown. Although it is not jet black like ink, at first glance it appears comparable in color to ink, and the brush strokes are visible, making it an ideal color for practice.

[0032] The ink-like composition of the present embodiment can be used, for example, as a substitute for ink, a paint, a liquid cosmetic, and the like.

[0033] [Writing instruments] The writing instrument according to this embodiment has a barrel having a pen tip at one end and a reservoir containing the ink-like composition of the present invention. Examples of such writing instruments include brush pens, ballpoint pens, fountain pens, felt-tip pens, markers, magic markers, stamps, etc.

[0034] [Writing implement set] The writing instrument set according to this embodiment includes a writing instrument and an ink-like composition container that contains the ink-like composition of the present invention. The composition container can be made of an appropriate material such as resin, metal, or paper. When the writing implement set is a calligraphy set, it preferably has a brush as a writing implement and a bottle containing the ink-like composition of the present invention, and optionally includes an inkstone and the like. When the writing implement set is a paint set, it preferably has a brush as a writing implement and a tube containing the ink-like composition of the present invention, and optionally also includes tubes containing other colors, a palette, a brush washer (a bucket for washing brushes), etc. [Example]

[0035] The present invention will be specifically explained below with reference to examples, but the present invention is not limited to these examples.

[0036] The same amount of each of the ink-like compositions A to F shown in Table 1 below was applied to a 100% cotton fabric using a dropper. For each ink-like composition, the following humic acid solids concentration, pH, weight average molecular weight, and melanic index (MI) were measured, and these are also shown in Table 1. Ink-like compositions A to D are commercially available liquid humic acid products. Ink-like composition E is commercially available ink whose active ingredient is carbon (carbon black). Ink-like composition F is commercially available disappearing ink (phenolphthalein).

[0037] (humic solids concentration) The solid humic acid concentrations in the ink-like compositions A to D were calculated by the following method. First, the total organic carbon concentration (TOC) was measured using a total organic carbon analyzer (Shimadzu TOC-L) by catalytic combustion oxidation. The ink-like composition was adjusted to pH 1.0 by adding hydrochloric acid, and then centrifuged at 5,000 × g for 10 minutes to precipitate humic acid. The TOC of the supernatant was then measured to quantify fulvic acid. The TOC of humic acid was calculated by subtracting the TOC measurement of fulvic acid from the TOC measurement of the ink-like composition. The humic solids concentration was calculated by multiplying these TOC values ​​by a coefficient. Generally, there is a strong correlation between TOC and humic mass. While this varies depending on the type of lignite used as a raw material, the humic mass can be estimated to be 1.4 to 2.0 times the TOC. The humic acid solids concentration was calculated by multiplying the TOC of humic acid by a coefficient of 1.7. In addition, the fulvic acid solids concentration was calculated by multiplying the TOC of fulvic acid by a coefficient of 2.0.

[0038] (pH measurement) The pH was measured by the glass electrode method at 20°C while stirring each ink-like composition with a magnetic stirrer.

[0039] (Weight average molecular weight) The weight-average molecular weight of humic substances was measured by HPSEC (GPC) using a Waters ACQUITY APC System. The columns used were a 2.5 μm, 4.6 mm x 150 mm ACQUITY UPLC Protein BEH SEC Column and a 1.7 μm, 4.6 mm x 150 mm ACQUITY UPLC Protein BEH SEC Column, connected together. Polystyrene sodium sulfonate was used as the standard sample, and the detection wavelength was 260 nm. The mobile phase was 100 mmol / L sodium phosphate buffer containing 20% ​​acetonitrile by mass, with a flow rate of 0.3 mL / min and a column temperature of 40°C (column oven setting).

[0040] [Melanic Index (MI)] India ink compositions A to D were diluted with pure water and 0.5 mol / L aqueous sodium hydroxide to a pH of 12, and the absorbance at 450 nm and 520 nm was measured using pure water as a blank. If the absorbance at 450 nm was 1.0 or greater, 0.1 mol / L aqueous sodium hydroxide was added to adjust the absorbance to 0.8 or greater but less than 1.0, and then the absorbance at 520 nm was measured. The ratio of "absorbance at 450 nm / absorbance at 520 nm" was calculated and used as MI.

[0041] The color of each fabric and the visibility of brush strokes were observed immediately after application of the ink-like composition, and the degree of color fading after washing was also confirmed. Discoloration due to ultraviolet irradiation using metal halides was also evaluated. The results are shown in Table 1.

[0042] [Table 1]

[0043] In the observation results of the colors in Table 1 above (dyeing on calligraphy paper), A is a tasteful dark brown color with good visibility of the brush strokes, making it suitable for practice. B is a slightly light brown color that looks a little strange, but the brush strokes are visible, and C is pitch black, meaning that the brush strokes are completely invisible. Furthermore, after washing, the ink in the examples according to the present invention almost completely disappeared, while the ink in Composition E remained pitch black and did not come off. Composition F lost its color after washing. On the other hand, with regard to fading due to ultraviolet rays, the products according to the present invention did not fade at all, while Composition F showed a tendency to fade.

Claims

1. An ink-like composition containing humic substances.

2. 2. The ink-like composition according to claim 1, wherein the solids concentration of the humic substances is 3% by mass or more.

3. 2. The ink-like composition according to claim 1, wherein the humic substance is one or more selected from the group consisting of fulvic acid, humic acid, and humin.

4. 2. The ink-like composition according to claim 1, which has a pH of 2 to 8.

5. 2. The ink-like composition according to claim 1, wherein the weight-average molecular weight of the humic substance is 500 or more.

6. 2. The ink-like composition according to claim 1, wherein the melanic index of said humic substances is 4 or less.

7. A writing implement having a barrel with a pen tip at one end and a storage section containing the ink-like composition according to any one of claims 1 to 6.

8. A writing instrument set comprising a writing instrument and an ink-like composition container containing the ink-like composition according to any one of claims 1 to 6.

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