Solid ink

Abstract

To provide a solid ink that exhibits superior blackness and has excellent moldability and good appearance and good mounting properties.SOLUTION: A solid ink includes a black pigment, and a mixture of partially saponified polyvinyl alcohol having a saponification degree of 87-89 mol% and a degree of polymerization of 1000-1700, and fully saponified polyvinyl alcohol having a saponification degree of 98-99 mol% and a degree of polymerization of 500-2400. A weight ratio of the partially saponified polyvinyl alcohol and the fully saponified polyvinyl alcohol in the mixture is 50:50 to 75:25. A blending rate of the mixture to the black pigment is 50-60 wt.% in terms of outer percentage.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to solid ink. [Background technology]

[0002] Solid ink is used together with inkstones in calligraphy and penmanship, and is one of the calligraphy tools used to create ink by grinding it into the ink chamber of a wet inkstone.

[0003] Traditionally, this type of solid ink was produced by mixing a solution of natural resin (animal) glue with soot, adding fragrance to the mixture, molding it, and drying it. Glue is an animal protein extracted by adding water to the bones, skin, or tendons of cows, horses, deer, etc., and boiling it. Soot is extracted by burning a wick in vegetable oil placed in a clay pot, and then collecting the soot that adheres to the clay pot's lid.

[0004] However, because conventional ink sticks use animal glue, a natural resource, there is a risk that a sustainable and stable supply of raw materials may be compromised.

[0005] For this reason, Patent Document 1 discloses solid ink produced by kneading a polymer emulsion that becomes insoluble in water after the water evaporates, a water-soluble paste, and a pigment, followed by molding and drying. Patent Document 1 uses a water-soluble paste such as polyvinyl alcohol instead of glue. In Example 2, the polyvinyl alcohol used is Brand #205 manufactured by Kuraray Co., Ltd. Brand #205 is a partially saponified polyvinyl alcohol with a degree of saponification of 86.5 to 89 mol% and a degree of polymerization of 500. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Special Publication No. 51-4128 Summary of the Invention [Problem to be solved by the invention]

[0007] Generally, when solid ink is ground into the ink chamber of a wet inkstone, the ink liquid is collected in the inkstone's ink pond, a brush is soaked in the ink liquid, and writing is done on paper such as gasenshi paper, a dark line called a baseline and a light colored area around the baseline called 'bloom' appear. When writing on paper with a brush using ink liquid obtained from solid ink containing glue as in the conventional method, the baseline of the writing appears in a dark ink color.

[0008] However, when the ground ink liquid obtained using the solid ink of Patent Document 1 is used to write on paper with a brush, there is a problem in that the ink color intensity of the base line of the handwriting is insufficient compared to solid ink containing glue. Furthermore, when the solid ink of Patent Document 1 is mounted as a calligraphy piece, polyvinyl alcohol is used, which makes it highly water-soluble and makes mounting difficult. In order to solve the above problems, the present invention aims to provide a solid ink that exhibits superior ink color properties, and also has excellent moldability, good appearance, and good mounting properties.

[0009] Here, "superior ink color" means that the base line of the handwriting has a deep ink color comparable to that of solid ink containing glue, the boundary between the base line and the surrounding bleeding is clear, and the bleeding is highly beautiful. "Excellent moldability" means that when the black pigment and a mixture of partially saponified polyvinyl alcohol and fully saponified polyvinyl alcohol, which will be described later, are kneaded together with water in the process of producing solid ink, the ink balls come together uniformly like freshly pounded rice cakes, and can be molded by hand. "Good appearance" means that the molded product after 14 days of drying in the process of producing solid ink has a smooth surface without any cracks or fractures. "Good mounting properties" means that when mounting a calligraphy work written with ink grinding liquid made by grinding solid ink, the black parts of the writing dissolve in water and the black is scattered on the paper, so the ink of the written characters does not run and turn the characters black, and the characters are beautifully mounted. [Means for solving the problem]

[0010] One embodiment of the present invention is solid ink containing a black pigment and a mixture of partially saponified polyvinyl alcohol having a degree of saponification of 87-89 mol% and a degree of polymerization of 1000-1700, and fully saponified polyvinyl alcohol having a degree of saponification of 98-99 mol% and a degree of polymerization of 500-2400. The weight ratio of the partially saponified polyvinyl alcohol to the fully saponified polyvinyl alcohol in the mixture is 50:50 to 75:25. The blend ratio of the mixture to the black pigment is 50-60% by weight. [Effects of the Invention]

[0011] The present invention can provide solid ink sticks that do not use animal glue, which is a natural resin, and that exhibit excellent ink color properties, as well as excellent moldability, good appearance, and good mounting properties. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described in detail. The present invention is not limited to the following description. Various modifications and improvements can be made to the embodiments, and such modifications and improvements can also be included in the present invention.

[0013] The solid ink according to the embodiment contains a black pigment and a mixture of partially saponified polyvinyl alcohol (hereinafter sometimes referred to as partially saponified PVA) having a degree of saponification of 87-89 mol% and a degree of polymerization of 1000-1700, and fully saponified polyvinyl alcohol (hereinafter sometimes referred to as fully saponified PVA) having a degree of saponification of 98-99 mol% and a degree of polymerization of 500-2400. The weight ratio of the partially saponified PVA to the fully saponified PVA in the mixture is 50:50 to 75:25. Expressed in weight percentages, the partially saponified PVA and the fully saponified PVA in the mixture are 50-75 wt% and 25-50 wt%, respectively. The blend ratio of the partially saponified PVA to the fully saponified PVA in the mixture is 50-60 wt%.

[0014] The inventors conducted extensive research into polyvinyl alcohol (PVA) as an alternative to glue, in order to develop a solid ink that exhibits superior ink color properties, as well as excellent moldability, good appearance, and good mounting properties. As a result, even when various partially saponified PVAs with different degrees of saponification and polymerization were used alone as a substitute for glue, it was difficult to obtain solid ink that exhibited excellent ink color properties and good mounting properties, although the moldability and appearance were excellent.

[0015] For this reason, the inventors focused on fully saponified PVA, which has lower water solubility than partially saponified PVA, and discovered that by using a mixture of these PVAs as a substitute for glue, it is possible to obtain solid ink with improved ink color intensity for the base line of handwriting. However, it was found that simply using a mixture of partially saponified PVA and fully saponified PVA as a substitute for glue resulted in deterioration of moldability and poor appearance, or the improvement in ink color, particularly the ink color of the base line of the handwriting, and the improvement in mounting properties were not achieved, resulting in inconsistent improvement effects.

[0016] Therefore, the inventors used a mixture of partially saponified PVA having a specific degree of saponification (87-89 mol%) and degree of polymerization (1000-1700) and fully saponified PVA having a specific degree of saponification (98-99 mol%) and degree of polymerization (500-2400), specified the weight ratio of partially saponified PVA to fully saponified PVA in the mixture to be 50:50 to 75:25, and further set the blending ratio of the mixture to a black pigment such as carbon black within a specific range of 50-60% by weight, thereby discovering a solid ink that exhibits superior ink color properties and also has excellent moldability, good appearance, and good mounting properties.

[0017] As the black pigment, for example, carbon black, lamp black (lamp black), etc. can be used.

[0018] If the weight ratio of partially saponified PVA to fully saponified PVA in the mixture deviates from the range of 50:50 to 75:25, the moldability of the solid ink decreases and the ink color intensity of the handwritten baseline decreases.

[0019] When the blend ratio of a partially saponified PVA and a fully saponified PVA to the black pigment is less than 50% by weight, cracks appear on the surface of the solid ink, impairing its appearance. On the other hand, when the blend ratio of the mixture to the black pigment is more than 60% by weight, the ink color intensity of the base line of the handwriting decreases and moldability decreases.

[0020] The solid ink according to the embodiment may further contain a fragrance. Examples of the fragrance that can be used include borneol and synthetic fragrances. The fragrance is preferably blended in an amount of 2 to 7% by weight based on the total weight of the mixture of the black pigment and PVA.

[0021] The solid ink according to the embodiment may further contain polyethylene glycol or glycerin. The polyethylene glycol preferably has a number average molecular weight of 200 to 30,000. The polyethylene glycol or glycerin is preferably blended in an amount of 5 to 40% by weight based on the total weight of the mixture of the black pigment and PVA.

[0022] Next, a method for producing solid ink according to an embodiment will be described. First, the partially saponified PVA and the fully saponified PVA are rapidly added to cold water while stirring, and after the desired swelling time has elapsed, the mixture is placed in a hot water bath and stirred again to prepare an aqueous solution of the PVA mixture. In this process, the weight ratio of the partially saponified PVA to the fully saponified PVA in the mixture is adjusted to 50:50 to 75:25.

[0023] Next, the black pigment and the prepared PVA mixture aqueous solution are stirred and mixed until they become homogeneous and can be molded by hand. During this process, the hardness of the ink ball varies depending on the amount of PVA mixture aqueous solution used, so water is added as needed to adjust the hardness of the resulting ink ball. The blend ratio of the mixture is adjusted to 50-60% by weight of the pure mixture relative to the black pigment. The desired amount of ink is removed from the resulting ink ball and kneaded on a board with a mixture of black pigment and PVA until it becomes more uniform. The kneaded ink ball is rolled out into a rod and placed in a mold, and pressed horizontally from above to mold it into the shape of the mold while copying the pattern on the mold. The ink removed from the mold is sandwiched between paper such as newspaper, and the newspaper is buried in wood ash inside the mold, allowing the ink ball to gradually dry within the wood ash in the mold. The dried product is then removed from the ash and shaped to produce solid ink. [Example]

[0024] The examples will be described in detail below. Example 1 First, we prepared Resin 1, a partially saponified PVA (Kuraray Co., Ltd., Brand 22-88) with a saponification degree of 87-89 mol% and a degree of polymerization of 1700, and Resin 2, a fully saponified PVA (Kuraray Co., Ltd., Brand 60-98) with a saponification degree of 98-99 mol% and a degree of polymerization of 2400. Next, the partially saponified PVA and fully saponified PVA were rapidly added to cold water with stirring. After allowing the mixture to swell for at least 30 minutes, the mixture was heated to 85°C for 2 hours and stirred again to prepare an aqueous solution of the PVA mixture. In this process, the weight ratios of partially saponified polyvinyl alcohol and fully saponified polyvinyl alcohol in the PVA mixture were adjusted to 75% and 25%, respectively.

[0025] Next, 50 g of carbon black (Mitsubishi Chemical Corporation: MA-100 brand, hereafter abbreviated as CB) was mixed with the prepared aqueous solution of PVA mixture using a stirring mixer (Dalton Co., Ltd.: Model DM) until the two became homogeneous and could be molded by hand. During this process, water was added as needed to adjust the hardness of the resulting ink ball. In addition, the aqueous solution of PVA mixture was blended so that the PVA mixture was 50% by weight of the CB to obtain an ink ball. Approximately 25g of the resulting ink ball was removed and kneaded on a board until the CB and PVA mixture was uniform. The kneaded ink ball was rolled out into a rod and placed in a mold. The ink ball was pressed horizontally from above with a lid and molded to the shape of the mold while copying the pattern on the mold. The ink ball removed from the mold was sandwiched between newspaper and the newspaper was buried in the wood ash inside the mold. The ink ball was allowed to dry gradually within the wood ash in the mold and left for 14 days to produce a molded product.

[0026] Example 2 A partially saponified PVA (brand 22-88, Kuraray Co., Ltd.) with a saponification degree of 87-89 mol% and a degree of polymerization of 1700 was prepared as resin 1, and a fully saponified PVA (brand 5-98, Kuraray Co., Ltd.) with a saponification degree of 98-99 mol% and a degree of polymerization of 500 was prepared as resin 2. An aqueous solution of the PVA mixture was prepared in the same manner as in Example 1. The weight ratios of the partially saponified polyvinyl alcohol and the fully saponified polyvinyl alcohol in the PVA mixture were adjusted to 75% and 25%, respectively. Next, a molded product was produced in the same manner as in Example 1 using 50 g of CB and the aqueous solution of the PVA mixture as in Example 1, except that the PVA mixture was blended so that the total weight ratio of the CB was 60%.

[0027] Example 3 Resin 1 was prepared using a partially saponified PVA (Kuraray Co., Ltd., Brand 22-88) with a saponification degree of 87-89 mol% and a degree of polymerization of 1700, and resin 2 was prepared using a fully saponified PVA (Kuraray Co., Ltd., Brand 11-98) with a saponification degree of 98-99 mol% and a degree of polymerization of 1000. An aqueous solution of the PVA mixture was prepared in the same manner as in Example 1. The weight ratios of the partially saponified polyvinyl alcohol and fully saponified polyvinyl alcohol in the PVA mixture were adjusted to 75% and 25%, respectively. Next, a molded product was produced in the same manner as in Example 1 using 50 g of the same CB as in Example 1 and the aqueous solution of the PVA mixture, except that the PVA mixture was blended so that the total weight ratio relative to the CB was 60% by weight.

[0028] Example 4 Resin 1 was prepared from a partially saponified PVA (Kuraray Co., Ltd., Brand 22-88) with a saponification degree of 87-89 mol% and a degree of polymerization of 1700, and resin 2 was prepared from a fully saponified PVA (Kuraray Co., Ltd., Brand 28-98) with a saponification degree of 98-99 mol% and a degree of polymerization of 1700. An aqueous solution of the PVA mixture was prepared in the same manner as in Example 1. The weight ratios of the partially saponified polyvinyl alcohol and fully saponified polyvinyl alcohol in the PVA mixture were adjusted to 75% and 25%, respectively. Next, a molded product was produced in the same manner as in Example 1 using 50 g of CB and the aqueous solution of the PVA mixture, as in Example 1, except that the PVA mixture was blended at an external ratio of 60% by weight relative to the CB.

[0029] Example 5 A molded product was produced in the same manner as in Example 1, except that the PVA mixture was mixed with the same CB as in Example 1 so that the external ratio was 60% by weight.

[0030] Example 6 A molded product was produced in the same manner as in Example 1, except that the weight ratios of partially saponified PVA (Kuraray Co., Ltd., Brand 22-88) and fully saponified PVA (Kuraray Co., Ltd., Brand 60-98) in the PVA mixture were adjusted to 50% and 50%, respectively.

[0031] Example 7 A molded product was produced in the same manner as in Example 1, except that the weight ratios of partially saponified PVA (Kuraray Co., Ltd., Brand 22-88) and fully saponified PVA (Kuraray Co., Ltd., Brand 60-98) in the PVA mixture were adjusted to 60% and 40%, respectively.

[0032] Example 8 A molded product was produced in the same manner as in Example 1, except that the weight ratios of partially saponified PVA (Kuraray Co., Ltd., Brand 22-88) and fully saponified PVA (Kuraray Co., Ltd., Brand 60-98) in the PVA mixture were adjusted to 70% and 30%, respectively.

[0033] Example 9 A molded product was produced in the same manner as in Example 1, except that the weight ratios of partially saponified PVA (Kuraray Co., Ltd., Brand 22-88) and fully saponified PVA (Kuraray Co., Ltd., Brand 60-98) in the PVA mixture were adjusted to 50% and 50%, respectively, and the aqueous solution of the PVA mixture was blended so that the PVA mixture accounted for 60% by weight of the CB used in Example 1.

[0034] Example 10 A molded product was produced in the same manner as in Example 1, except that the weight ratios of partially saponified PVA (Kuraray Co., Ltd., Brand 22-88) and fully saponified PVA (Kuraray Co., Ltd., Brand 60-98) in the PVA mixture were adjusted to 60% and 40%, respectively, and the aqueous solution of the PVA mixture was blended so that the PVA mixture accounted for 60% by weight of the CB used in Example 1.

[0035] Example 11 A molded article was produced in the same manner as in Example 1, except that the weight ratios of partially saponified PVA (Kuraray Co., Ltd., Brand 22-88) and fully saponified PVA (Kuraray Co., Ltd., Brand 60-98) in the PVA mixture were adjusted to 70% and 30%, respectively, and the aqueous solution of the PVA mixture was blended so that the PVA mixture accounted for 60% by weight of the CB used in Example 1.

[0036] (Comparative Example 1) First, carboxymethylcellulose (CMC) as resin 1 and gum arabic as resin 2 were added to cold water, along with 5 g of CB (as in Example 1). The mixture was stirred and mixed using a stirring mixer (DM model, manufactured by Dalton Co., Ltd.) until the CB, CMC, and gum arabic were homogenized and suitable for manual molding. In this process, the weight ratios of CMC and gum arabic were 75% and 25%, respectively. The CMC and gum arabic mixture was blended so that the total weight ratio of the CB was 100%. Approximately 25 g of the resulting ink ball containing CB, CMC, and gum arabic was removed and kneaded on a board until the CB, CMC, and gum arabic were homogenized. The kneaded ink ball was rolled into a rod and placed in a mold. The ball was pressed horizontally from above with a lid, allowing the ink to be molded into the shape of the mold while imprinting the pattern on the mold. The ink was removed from the mold, sandwiched between newspaper, and the newspaper was then buried in the wood ash inside the mold. The ink ball was allowed to slowly dry inside the wood ash in the mold, and after 14 days, a molded product was produced.

[0037] (Comparative Example 2) A molded product was produced in the same manner as in Example 1, except that a partially saponified PVA (Kuraray Co., Ltd.: Brand 22-88) with a saponification degree of 87 to 89 mol% and a polymerization degree of 1700 was used as Resin 1, and an aqueous solution of the partially saponified PVA alone was blended so that the partially saponified PVA accounted for 50% by weight of the CB used in Example 1.

[0038] (Comparative Example 3) A molded product was produced in the same manner as in Example 1, except that a partially saponified PVA (Kuraray Co., Ltd.: Brand 9-88) with a saponification degree of 87 to 89 mol% and a polymerization degree of 1000 was used as Resin 1, and an aqueous solution of the partially saponified PVA alone was blended so that the partially saponified PVA accounted for 60% by weight of the CB used in Example 1.

[0039] Comparative Example 4 A molded product was produced in the same manner as in Example 1, except that a partially saponified PVA (Kuraray Co., Ltd.: Brand 9-88) with a saponification degree of 87 to 89 mol% and a polymerization degree of 1000 was used as Resin 1, and an aqueous solution of the partially saponified PVA alone was blended so that the partially saponified PVA accounted for 70% by weight of the CB used in Example 1.

[0040] (Comparative Example 5) Fully saponified PVA (Kuraray Co., Ltd., Brand 60-98) with a degree of saponification of 98-99 mol% and a degree of polymerization of 2400 was used as Resin 2. As in Example 1, the fully saponified PVA was quickly poured into cold water while stirring, and after allowing it to swell for at least 30 minutes, it was placed in a hot water bath at 85°C for 2 hours and stirred again to prepare an aqueous solution of fully saponified PVA. At this time, the fully saponified PVA was dissolved in water, and ink beads were obtained by blending this aqueous solution so that the fully saponified PVA accounted for 60% by weight of the CB used in Example 1. However, the ink beads did not aggregate uniformly, and the ink did not have a uniform surface when molded, making it virtually impossible to evaluate as ink.

[0041] (Comparative Example 6) A partially saponified PVA (brand 22-88, Kuraray Co., Ltd.) with a saponification degree of 87-89 mol% and a degree of polymerization of 1700 was prepared as resin 1, and a fully saponified PVA (brand 60-98, Kuraray Co., Ltd.) with a saponification degree of 98-99 mol% and a degree of polymerization of 2400 was prepared as resin 2. An aqueous solution of the PVA mixture was prepared in the same manner as in Example 1. At this time, the weight ratios of the partially saponified PVA and the fully saponified PVA in the PVA mixture were adjusted to 40% and 60%, respectively. Next, a molded product was produced in the same manner as in Example 1 using the aqueous solution of the PVA mixture and 50 g of the same CB as in Example 1, except that the PVA mixture was blended at an external ratio of 60% by weight relative to the CB.

[0042] (Comparative Example 7) A partially saponified PVA (brand 22-88, Kuraray Co., Ltd.) with a saponification degree of 87-89 mol% and a degree of polymerization of 1700 was prepared as resin 1, and a fully saponified PVA (brand 60-98, Kuraray Co., Ltd.) with a saponification degree of 98-99 mol% and a degree of polymerization of 2400 was prepared as resin 2. An aqueous solution of the PVA mixture was prepared in the same manner as in Example 1. At this time, the weight ratios of the partially saponified PVA and the fully saponified PVA in the PVA mixture were adjusted to 80% and 20%, respectively. Next, a molded product was produced in the same manner as in Example 1 using the aqueous solution of the PVA mixture and 50 g of the same CB as in Example 1, except that the PVA mixture was blended at an external ratio of 60% by weight relative to the CB.

[0043] (Comparative Example 8) A partially saponified PVA (brand 22-88, Kuraray Co., Ltd.) with a saponification degree of 87-89 mol% and a degree of polymerization of 1700 was prepared as resin 1, and a fully saponified PVA (brand 60-98, Kuraray Co., Ltd.) with a saponification degree of 98-99 mol% and a degree of polymerization of 2400 was prepared as resin 2. An aqueous solution of the PVA mixture was prepared in the same manner as in Example 1. At this time, the weight ratios of the partially saponified PVA and the fully saponified PVA in the PVA mixture were adjusted to 60% and 40%, respectively. Next, a molded product was produced in the same manner as in Example 1 using the aqueous solution of the PVA mixture and 50 g of the same CB as in Example 1, except that the PVA mixture was blended at an external ratio of 40% by weight relative to the CB.

[0044] (Comparative Example 9) A partially saponified PVA (brand 22-88, Kuraray Co., Ltd.) with a saponification degree of 87-89 mol% and a degree of polymerization of 1700 was prepared as resin 1, and a fully saponified PVA (brand 60-98, Kuraray Co., Ltd.) with a saponification degree of 98-99 mol% and a degree of polymerization of 2400 was prepared as resin 2. An aqueous solution of the PVA mixture was prepared in the same manner as in Example 1. At this time, the weight ratios of the partially saponified PVA and the fully saponified PVA in the PVA mixture were adjusted to 60% and 40%, respectively. Next, a molded product was produced in the same manner as in Example 1 using the aqueous solution of the PVA mixture and 50 g of the same CB as in Example 1, except that the PVA mixture was blended at an external ratio of 70% by weight relative to the CB.

[0045] The molded products obtained in Examples 1 to 11 and Comparative Examples 1 to 4 and 6 to 9 were evaluated for moldability, appearance, mounting properties and ink color as described below.

[0046] 1)Moldability When kneading the CB and PVA composition in the molding production process, if the ink balls were not uniform and fell apart, or were too hard and did not come together into a single ball, they were marked as "X." If the ink balls were uniform and came together into a single ball like freshly pounded mochi, and could be molded by hand, they were marked as "O."

[0047] 2) Appearance (cracks, surface condition) The appearance of the molded product after 14 days of drying was observed. If cracks, fissures, or roughness were observed on the surface, it was rated as "X", and if no cracks or fissures were observed and the surface was smooth, it was rated as "Good".

[0048] 3) Mounting After air-drying for 14 days at room temperature, the molded piece was ground for two minutes against the ink chamber of a natural inkstone with 2 mL of water dropped on it. The ink was then collected in the inkstone's ink pond, and the undiluted ink was soaked into a brush and used to write on rice paper. After the ink had completely dried, the paper was placed on a smooth mounting board with the writing surface facing backwards, and water was sprayed on the paper with a spray bottle to moisten the entire surface. Next, the paper was smoothed out with a brush to remove any excess water, and then starch paste was applied evenly to the surface with another brush. Immediately afterwards, the mounting paper was placed on top and rubbed from the center to the outside with an unglued brush to ensure that the mounting paper adhered to the paper. The rice paper with the mounting paper attached was then peeled off the mounting board, turned over, and attached to another location with a small amount of water so that the written lines were facing outwards, and then left to air-dry at room temperature. After confirming that the drawing paper on the mounting board was sufficiently dry, it was peeled off from the board. If the black ink could be observed in areas other than where the lines had been written on the drawing paper, it was rated as "X", and if the black ink could not be observed in areas other than where the lines had been written on the drawing paper and it looked beautiful, it was rated as "O".

[0049] 4) Ink color After 14 days, the molded product was ground for 2 minutes in the ink chamber of a natural inkstone with 2 mL of water dropped on it, and the ink was collected in the ink pond of the natural inkstone. The undiluted ink was soaked into a brush and used to write on rice paper. A solution of the undiluted ink diluted 4 times with water was also soaked into a brush and used to write on rice paper. A solution of the undiluted ink diluted 16 times with water was also soaked into a brush and used to write on rice paper. After that, each rice paper was dried, and compared to when using regular solid ink containing glue, cases where the ink color was whitish, the boundary between the bleeding and the baseline was unclear, and the beauty of the bleeding was poor were evaluated as "X", and cases where the ink color was clear, the boundary between the bleeding and the baseline was clear, and the beauty of the bleeding was excellent were evaluated as "O".

[0050] The evaluation results obtained are shown in Tables 1 and 2 below.

[0051] [Table 1]

[0052] [Table 2]

[0053] As is clear from Table 1, the molded products (solid ink sticks) of Examples 1 to 11, which use a mixture of partially saponified PVA with a specific degree of saponification and polymerization and fully saponified PVA with a specific degree of saponification and polymerization, in which the weight ratios of the partially saponified PVA and the fully saponified PVA in the mixture are 50 to 75% and 25 to 50%, respectively, and in which the blending ratio of the mixture to carbon black (CB) is 50 to 60% by weight, have excellent moldability, appearance, and mounting properties, as well as excellent ink color properties.

[0054] In contrast, as is clear from Table 2 above, the molded product (solid ink) of Comparative Example 1, in which carbon black was blended with a mixture of carboxymethyl cellulose (CMC) as resin 1 and gum arabic as resin 2, with the CMC and gum arabic mixture ratios of 75% and 25%, respectively, and the ratio of the mixture to carbon black (external ratio) was 100% by weight, had good moldability but was inferior in appearance, mounting properties, and ink color properties.

[0055] It can be seen that the molded products (solid ink) of Comparative Examples 2 to 4, which used only partially saponified PVA as Resin 1, had good moldability and generally good appearance, but were inferior in mounting properties and ink color properties.

[0056] The moldings (solid ink) of Comparative Example 6, in which the weight ratios of partially saponified PVA (resin 1) and fully saponified PVA (resin 2) are outside the range of the present invention (weight ratios of partially saponified PVA and fully saponified PVA are 50-75% and 25-50%, respectively), are 40% and 60%, respectively, and the moldings (solid ink) of Comparative Example 7, in which the weight ratios of partially saponified PVA and fully saponified PVA are 80% and 20%, respectively, are found to have good mounting properties but are poor in molding properties, appearance, and ink color properties.

[0057] Furthermore, the molded product (solid ink) of Comparative Example 8, in which the mixing ratios of partially saponified PVA (resin 1) and fully saponified PVA (resin 2) were 60% and 40%, respectively, but the aqueous solution of the PVA mixture was blended so that the PVA mixture accounted for 40% by weight of the CB, and the molded product (solid ink) of Comparative Example 9, in which the mixing ratios of partially saponified PVA and fully saponified PVA were the same as those of 60% and 40%, respectively, but the aqueous solution of the PVA mixture was blended so that the PVA mixture accounted for 70% by weight of the CB, were found to have good mounting properties but were poor in moldability, appearance, and ink color.

Claims

1. a black pigment; and a mixture of a partially saponified polyvinyl alcohol having a saponification degree of 87 to 89 mol% and a polymerization degree of 1000 to 1700 and a fully saponified polyvinyl alcohol having a saponification degree of 98 to 99 mol% and a polymerization degree of 500 to 2400, a weight ratio of the partially saponified polyvinyl alcohol to the fully saponified polyvinyl alcohol in the mixture is 50:50 to 75:25; The mixture is a solid ink stick, the blending ratio of which to the black pigment is 50 to 60% by weight.

2. 2. The solid ink according to claim 1, further comprising a fragrance.

3. 3. The solid ink according to claim 1 or 2, further comprising polyethylene glycol or glycerin.

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