Ink and ink ribbons that use the ink

Abstract

To provide: an ink used for an ink ribbon for an impact printer, which can increase the number of printable characters, especially the number of characters readable by an optical reading device without using additional parts and the like when the ink ribbon is stored in an ink ribbon cassette and the like and without making length of the ink ribbon to be stored longer; and an ink ribbon using the ink.SOLUTION: Provided is an ink to be used for an ink ribbon that retains an ink in a ribbon substrate comprising fibers. The ink contains carbon black as a coloring pigment. The carbon black has a volatile matter content of 7.0% to 8.5%, a DBP absorption amount of 60 cm3 / 100 g to 78 cm3 / 100 g, and a nitrogen adsorption specific surface area of 300 m2 / g to 390 m2 / g.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to inks used in ink ribbons for impact printers and ink ribbons using said inks, and more particularly to black inks using carbon black and black ink ribbons using said inks. [Background technology]

[0002] Traditionally, ink ribbons used in dot impact printers consist of a substrate (base) made of cotton, silk, synthetic fiber, or other material coated with an appropriate amount of oil-based ink, with the ink embedded in the substrate.

[0003] Such ink ribbons are usually used by joining both ends of a single ink ribbon together to form a loop. By storing the looped ink ribbon in an ink ribbon cassette or the like, the ink ribbon is repeatedly run in the longitudinal direction of the loop, and the ink contained in the ink ribbon is The printer uses it to print until it runs out and the printer can no longer print with sufficient density.

[0004] Such ink ribbons have the advantageous feature that the number of characters that can be printed is extremely large compared to the length of the ink ribbon, since the loop of the ink ribbon can be used repeatedly for printing over many, even dozens of times. For this reason, various proposals have been made to further improve this advantageous feature.

[0005] For example, Patent Document 1 proposes an ink ribbon cassette characterized in that a sheet-like material is attached to at least one inner wall surface of an ink ribbon storage chamber, and the coefficient of dynamic friction between the surfaces of the sheet-like material that come into contact with the ink ribbon is 0.45 or less, and the static contact angle of oleic acid on the surface of the sheet-like material that comes into contact with the ink ribbon is 60° or more.

[0006] While being able to store a larger ink ribbon in an ink ribbon cassette does not necessarily increase the number of prints per length of ink ribbon, it does allow for a larger number of characters to be printed with an ink ribbon cassette of the same size. However, if too many ink ribbons are stored in the ink ribbon storage chamber, the ink ribbon may become unable to move within the ink ribbon storage chamber, causing problems with the ink ribbon's running, making it impossible to store many ink ribbons in the ink ribbon storage chamber. For this reason, Patent Document 1 proposes an ink ribbon cassette that reduces the coefficient of dynamic friction within the ink ribbon storage chamber, thereby enabling the ink ribbon to move smoothly within the ink ribbon storage chamber, thereby preventing problems caused by abnormal ink ribbon transport even when a longer-than-normal ink ribbon is packed into the ink ribbon cassette (ink ribbon storage chamber).

[0007] Furthermore, Patent Document 2 and other documents propose an ink ribbon cassette that can replenish ink from a refill ink tank to the ink ribbon. In the ink ribbon cassette of Patent Document 2, ink is supplied from the ink tank to the ink ribbon as the ink ribbon runs inside the ink ribbon cassette, which makes it possible to increase the number of prints per length of the ink ribbon.

[0008] However, as described above, the ink ribbon cassette of Patent Document 1 does not allow for an increase in the number of prints per length of ink ribbon, and requires an additional part, a sheet-like material to be attached to the inner wall surface. Since the sheet-like material must be attached to the inner wall surface, when the ink ribbon cassette is used for a long period of time, it may become difficult to attach the sheet-like material. There is also a risk that the adhesive used in the ink ribbon storage chamber may leak out and adhere to the ink ribbon, causing the ink ribbon to malfunction.

[0009] Furthermore, the ink ribbon cassette of Patent Document 2 requires the provision of a refill ink tank in the ink ribbon cassette, which makes the ink ribbon cassette larger. Also, since it is necessary to ensure that liquid ink does not leak from the refill ink tank and that ink is reliably supplied from the refill ink tank to the ink ribbon, many additional parts are required, such as a part for retaining ink in the ink tank and a part for supplying ink from the part for retaining ink in the ink tank to the outside. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Publication No. 2019-55580 [Patent Document 2] Japanese Patent Application Publication No. 9-109522 Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention has been made in view of the above circumstances, and the problem that the present invention aims to solve is to provide an ink to be used in an ink ribbon for an impact printer, which, when stored in an ink ribbon cassette or the like, can increase the number of characters that can be printed, and in particular the number of characters that can be read by an optical reading device, without using additional parts or increasing the length of the stored ink ribbon, and an ink ribbon using said ink. [Means for solving the problem]

[0012] The first invention is an ink used for an ink ribbon that holds ink on a ribbon fabric made of fiber, and contains carbon black as a coloring pigment, and the carbon black has a volatile content of 7.0% or more and 8.5% or less, and a DBP absorption of 60 cm 3 / 100g or more 78cm 3 / 100g or less, and nitrogen adsorption specific surface area is 300m 2 / g or more 390m 2 / g or less.

[0013] A second aspect of the present invention is an ink ribbon characterized in that the ink according to the first aspect is held in a ribbon fabric made of fibers. [Effects of the Invention]

[0014] In the present invention, the ink for the ink ribbon for the impact printer has a volatile content of 7.0% or more and 8.5% or less, and a DBP absorption of 60 cm 3 / 100g or more 78cm 3 / 100g or less and nitrogen adsorption specific surface area of ​​300m 2 / g or more 390m 2 By using carbon black with a carbon black content of 0.1% or less per unit length of ink ribbon, the number of characters that can be printed per length of ink ribbon, particularly the number of characters that can be read by an optical reader, increases compared to conventional ink ribbons for impact printers. Therefore, by using the ink for ink ribbons for impact printers of the present invention, it is now possible to provide ink for use in ink ribbons for impact printers, which, when stored in an ink ribbon cassette or the like, can increase the number of printable characters without using additional parts or increasing the length of the stored ink ribbon, and ink ribbons using this ink. DETAILED DESCRIPTION OF THE INVENTION

[0015] The ink and ink ribbon of the present invention will be described in more detail below.

[0016] Generally, liquid inks used in ink ribbons for impact printers contain the following components: Ingredients Weight% Colorants (pigments, dyes) 5-40 Oil 20~80 Pigment dispersant 5~20 As the fabric (base fabric) for the fabric ribbon to be impregnated with the ink, for example, woven fabrics made of various fibers such as nylon, polyester, cotton, and silk can be used. The thickness of the ribbon fabric is preferably 80 μm or more and 140 μm or less. If the ribbon fabric is thinner than 80 μm, it will not be able to be impregnated with a sufficient amount of ink, and the number of characters that can be printed per length of ink ribbon will be very small. On the other hand, if the ribbon fabric is thicker than 140 μm, the fabric will be too thick and the characters printed with the head pin of the impact printer will be crushed. In addition, the amount of ink to be impregnated into the fabric (per square meter of fabric area) will be large. 2 The weight of ink impregnated per unit is 8g / m 2 More than 21g / m 2 The amount of ink impregnated into the fabric is preferably 8g / m 2 If the ink density is less than 21g / m, the number of characters that can be printed per length of ink ribbon will be very small. 2 If it exceeds this, the printed characters will bleed and the printed characters will look ugly.

[0017] Examples of oils commonly used in inks include mineral oils such as motor oil, vegetable oils such as rapeseed oil, castor oil, and soybean oil, animal oils such as cow's foot oil, olefin polymerized oils such as liquid paraffin, ethylene hydrocarbon oils, and butylene hydrocarbon oils, diester oils such as azelaic acid diester and adipic acid diester, silicone oils such as linear dimethylpolysiloxane, fatty acids such as isostearic acid and oleic acid, fatty acid esters such as trimethylolpropane fatty acid ester, glycerin fatty acid ester, propylene glycol fatty acid ester, polyethylene glycol fatty acid ester, castor oil fatty acid ester, trimellitic acid ester, and sorbit fatty acid ester, esters such as phthalate esters and phosphate esters, and ethers such as polyoxyethylene alkyl ether and polyoxyethylene sorbitan alkyl ether.

[0018] The viscosity of the oil used in the ink is preferably low in order to extend the printing life of the ink ribbon, and the viscosity of the oil at 25°C is preferably 400 mPa·s or less. Furthermore, the viscosity at 25°C is more preferably 50 mPa·s or less. If the viscosity of the oil at 25°C exceeds 400 mPa·s, it becomes difficult to adjust the ink to the viscosity range suitable for printing described below.

[0019] The ink may be a dye-based ink that uses only dye as the colorant, a dye-pigment-based ink that uses a combination of dye and pigment, or a pigment-based ink that uses only pigment, but a dye-pigment-based ink that uses a combination of dye and pigment is preferred because it satisfies the characteristics required of this type of ink: reduced wear on the dot pins of the printer head, readability with an optical character reader (OCR suitability), and long visual print life. Here, readability with an optical character reader (OCR suitability) refers to the ability to print a large number of characters that can be read by infrared reflection, and the long print life that is the object of the present invention refers to the ability to print a large number of characters that can be read by infrared reflection.

[0020] The dyes used in the ink include, for example, one or more of nigrosine dye, oil black, methyl violet base, spiron black, and varifast black.

[0021] The pigment used in the ink may be one or more of inorganic pigments such as carbon black, and organic pigments such as aniline black, phthalocyanine blue, and brilliant carmine. Among these, it is preferable to contain carbon black in order to improve OCR suitability. With ink that does not contain carbon black, it is very difficult to improve OCR suitability, and it is not possible to print many characters that can be read by an optical character reader.

[0022] On the other hand, the more carbon black an ink contains, the more wear occurs on the dot pins of the printer head. For this reason, it is essential that the ink contains carbon black, but it is preferable to achieve OCR suitability with as little carbon black as possible, i.e., to be able to print as many characters as possible that can be read by infrared reflection.

[0023] Ink ribbons for impact printers transfer ink from the ink ribbon to the print target, such as paper, by striking the ink ribbon against the print target with head pins protruding from the print head. The ink on the ink ribbon where the ink has been transferred is reduced by the amount of ink transferred. Therefore, if the ink ribbon used for printing is not replenished with ink, the print density will decrease when the same area of ​​the ink ribbon is used again. However, if the ink used in the ink ribbon has sufficient fluidity, the area where the ink has been removed during printing will be replenished with ink from the surrounding areas where the ink has not been removed. Therefore, even if the same area of ​​the ink ribbon is used again, the print density can be approximately the same as the previous time. Therefore, it is believed that improving the ink fluidity of ink ribbons used in this type of impact printer can extend the print life of the ink ribbon.

[0024] However, improving ink fluidity does not necessarily extend the printing life of an ink ribbon. Ink fluidity can be improved by lowering ink viscosity. Lowering ink viscosity makes it easier for ink used during printing to be replenished from peripheral portions of the ink ribbon that are not used during printing, but at the same time, the amount of ink transferred from the ink ribbon to the printed material during printing is greater than necessary. If the amount of ink transferred from the ink ribbon to the printed material during printing is greater than necessary, the ink will be depleted quickly, which can shorten the printing life. Furthermore, attempting to improve printing life by simply lowering ink viscosity can result in secondary problems, such as the amount of ink used per print being greater than necessary, causing printed characters to bleed and appear unsightly, or the ink ribbon coming into contact with the printed material near the print head and staining the printed material.

[0025] Thus, in order to extend the printing life of an ink ribbon, the ink fluidity, i.e., the ink viscosity, must be low enough so that the ink used during printing can be easily replenished from the surrounding ink ribbon, and high enough so that the amount of ink transferred from the ink ribbon to the printed material during printing does not become more than necessary.

[0026] Furthermore, the preferred ink viscosity for extending the printing life of the ink ribbon varies depending on the length of the ink ribbon and the printer's running speed. For example, if the ink ribbon length (the length of the ink ribbon loop) is long and the printer's running speed is slow, the preferred ink viscosity will be higher in the former case than in the latter case. Since a longer time elapses between the used portion of the ink ribbon and the printer's running speed compared to the latter case, even if the ink viscosity is relatively high, the ink in the used portion of the ink ribbon can be replenished from the unused peripheral portion of the ink ribbon by the time the ink ribbon is used again. In contrast, since a shorter time elapses between the used portion of the ink ribbon and the printer's running speed compared to the former case, if ink with a preferred viscosity is used for the former case, the ink in the used portion of the ink ribbon cannot be replenished from the unused peripheral portion of the ink ribbon by the time the ink ribbon is used again.

[0027] In addition to the viscosity of the ink, another factor that extends the printing life of an ink ribbon is the thixotropy of the ink. This type of ink ribbon is thixotropic, and when the print head pins strike the ink ribbon, shear stress is generated in the ink, reducing the ink viscosity in the areas struck by the print head pins. Therefore, if the ink has the property of easily reducing its viscosity due to its thixotropy (hereinafter, this property will be referred to as having high thixotropy), the ink viscosity will be reduced in the areas used for printing. With ink ribbons for impact printers, only the ink ribbon in the area used for printing (hereinafter, referred to as the printing area) is struck by the print head pins, so the ink viscosity only in the printing area decreases, and the ink viscosity of the ink ribbon in the surrounding areas not struck by the print head pins (hereinafter, referred to as the peripheral area) does not decrease. Therefore, if the ink has high thixotropy, the viscosity of the ink in the ink ribbon in the printing area drops significantly, allowing a large amount of ink to be transferred from the ink ribbon to the print target, whereas the viscosity of the ink in the ink ribbon in the peripheral area does not drop, preventing a sufficient amount of ink from being supplied from the peripheral area to the printing area. As a result, more ink is transferred from the printing area to the print target than is supplied from the peripheral area to the printing area, resulting in less ink in the printing area and a lower print density transferred to the print target. As a result, when using ink with high thixotropy, the number of characters that can be printed is reduced compared to when using ink with low thixotropy, and the printing life of the ink ribbon is shortened.

[0028] Whether the ink viscosity is low or high, the thixotropy of the ink increases, reducing the amount of ink supplied to the printing area, so that even though ink remains in the peripheral areas, there is very little ink in the printing area, making it impossible to print with sufficient density and shortening the printing life of the ink ribbon. Therefore, whether the ink viscosity is low or high, if the thixotropy of the ink can be reduced, the printing life of the ink ribbon can be extended.

[0029] As mentioned above, the preferred ink viscosity for extending the printing life of the ink ribbon varies depending on the length of the ink ribbon used and the running speed of the printer. However, regardless of the viscosity of the ink, the printing life of the ink ribbon can be extended if the thixotropy of the ink can be reduced.

[0030] The fluidity of ink, i.e., ink viscosity, can be adjusted by the properties and content ratios of each component contained in the ink. That is, it can be adjusted by changing the content ratios of pigments, dyes, oils, and other materials contained, or the viscosity of the oils contained. Furthermore, the thixotropy of ink can also be adjusted to a certain extent by simply changing the content ratios of these materials. However, conventional methods have not been able to produce inks with even lower thixotropy, and it has not been possible to further extend the printing life of ink ribbons.

[0031] As a result of the inventors' earnest efforts to develop ink materials that exhibit lower thixotropy, it was found that the thixotropy of ink can be reduced by using a specific carbon black. 3 / 100g or more 78cm 3 / 100g or less, and the nitrogen adsorption specific surface area is 300m 2 / g or more 390m 2 It was found that by using carbon black that simultaneously satisfies the range of 0.1g / g or less in ink, the thixotropy of the ink can be made lower than that of conventional inks.

[0032] The thixotropy of the ink can be measured by the following method: Using a cone-plate rotational (coaxial double cylinder) viscometer RotoVisco 1 manufactured by Thermo Fisher Scientific Co., Ltd., at 25°C, the shear stress of the ink is measured while the shear rate is increased at a constant rate from 0 (1 / s) to 600 (1 / s) over three minutes (hereinafter referred to as the shear stress during acceleration), then the shear stress of the ink is measured for 10 minutes with the shear rate fixed at 600 (1 / s), and then the shear stress of the ink is measured while the shear rate is decreased at a constant rate from 600 (1 / s) to 0 (1 / s) over one minute (hereinafter referred to as the shear stress during deceleration).

[0033] Next, a graph showing the measurement results was created with shear rate (1 / s) on the X axis and shear stress (Pa) on the Y axis, and the thixotropy of the ink (Pa / s) was determined by subtracting the value obtained by integrating the shear stress during deceleration from a shear rate of 0 (1 / s) to 600 (1 / s) from the value obtained by integrating the curve showing the shear stress during acceleration from a shear rate of 0 (1 / s) to 600 (1 / s). In other words, the thixotropy of the ink in the present invention is the area enclosed by the curve showing the shear stress during acceleration at Y=0, X=0, X=600 and the area enclosed by the curve showing the shear stress during deceleration at Y=0, X=0, X=600, from the area enclosed by the curve showing the shear stress during acceleration at Y=0, X=0, X=600.

[0034] The thixotropy value of the ink of the present invention is preferably 4000 Pa / s or less. If the thixotropy value is 4000 Pa / s or less and the ink viscosity is a value suitable for extending the printing life of the ink ribbon, depending on the length of the ink ribbon used and the running speed of the printer, then the ink in the printing area will not be consumed more than necessary for printing, and the ink in the printing area used for printing will be reliably replenished with ink in the surrounding areas, allowing for more effective use of the ink throughout the ink ribbon. Therefore, if the ink viscosity is set to a value suitable for extending the printing life of the ink ribbon, depending on the length of the ink ribbon used and the running speed of the printer, and the thixotropy can be reduced, the printing life of the ink ribbon can be further extended.

[0035] In the present invention, the ink viscosity is the value obtained by dividing the shear stress after 10 minutes by the shear rate when the shear rate is fixed at 600 (1 / s) and the shear stress of the ink is measured for 10 minutes in measuring the value indicating the thixotropy.

[0036] The viscosity of ink used in impact printer ink ribbons is typically between 300 mPa·s and 3500 mPa·s. As mentioned above, inks with higher viscosities, close to 3500 mPa·s, are used for long ink ribbons and slow printer speeds, while inks with lower viscosities, around 300 mPa·s, are used for short ink ribbons and fast printer speeds. Ink viscosity below 300 mPa·s makes the ink too fluid, shortening the print life of the ink ribbon even when used in short ink ribbons and fast printer speeds. Ink viscosity above 3500 mPa·s also reduces the ink's flowability, potentially shortening the print life of the ink ribbon and potentially smearing the print surface when the ink ribbon comes into contact with the print surface. On the other hand, ink viscosity above 3500 mPa·s makes the ink less fluid, and even if the ink's thixotropy value is below 4000 Pa·s, it does not extend the print life of the ink ribbon.

[0037] In addition to the above components, the ink used in the present invention may contain, as necessary, additives such as a resin, an antioxidant, a preservative, an anti-mold agent, and a dispersant. Examples of resins that can be used include styrene-based resins, acrylic-based resins, phenolic resins, natural rubbers, and synthetic rubbers. Since a pigment is used, it is preferable to use a pigment dispersant to improve the dispersibility of the pigment.

[0038] The ink used in the present invention can be prepared by kneading the above components using a roll mill, sand mill, or the like.

[0039] (Example) The present invention will be explained in more detail using the following examples and comparative examples. However, the present invention is not limited to these examples. Hereinafter, when the amount of each material is expressed as "parts," it means "parts by weight" unless otherwise specified.

[0040] (carbon black) Carbon blacks were prepared with the volatile content, DBP absorption amount, and nitrogen adsorption specific surface area shown in Table 1. The volatile content, DBP absorption amount, and nitrogen adsorption specific surface area of ​​each carbon black were measured by the following methods.

[0041] (Measurement of volatile content of carbon black) Carbon black was placed in a crucible and heated at 950°C for 7 minutes. After cooling, the mass was measured and the weight loss was calculated. The percentage (%) of the weight loss relative to the original mass was used to determine the volatile content.

[0042] (DBP absorption amount) DBP absorption (cm 3 / 100g) was determined in accordance with JIS K 6217-4 by using an S-500 absorption measuring device (manufactured by Asahi Research Institute Co., Ltd.) to detect the torque generated by the change in viscosity characteristics when DBP is added to carbon black, and converting the amount of DBP added at 70% of the maximum torque into a value per 100g of sample.

[0043] (Carbon black nitrogen adsorption specific surface area measurement) Measurements were carried out in accordance with JIS K6127-2.

[0044] (Table 1) TIFF0007825530000001.tif36170

[0045] (Ink preparation) Example 1 Carbon black A in Table 1 was used as the carbon black, and the materials were mixed according to the recipe shown below and kneaded in a three-roll mill to prepare an ink. Prescription wt% Carbon Black A (100% solids) 5 Aniline Black (100% solids) 12 Trimethylolpropane fatty acid ester 71 Dye solution (contains 25% dye) 5 Pigment Dispersant (100% solids) 7

[0046] Example 2 Ink of Example 2 was prepared in the same manner as in Example 1, except that the carbon black was changed to that shown in Table 2.

[0047] Example 3 The ink of Example 3 was prepared in the same manner as in Example 1, except that the ink materials were changed to the following formulation. Prescription wt% Carbon Black A (100% solids) 5 Aniline Black (100% solids) 12 Liquid Paraffin 71 Dye solution (contains 25% dye) 5 Pigment Dispersant (100% solids) 7

[0048] Example 4 Ink of Example 4 was prepared in the same manner as in Example 3, except that the carbon black was changed to that shown in Table 2.

[0049] Example 5 The ink of Example 5 was prepared in the same manner as in Example 1, except that the ink materials were changed to the following formulation. Prescription wt% Carbon Black A (100% solids) 5 Aniline Black (100% solids) 12 Castor oil fatty acid ester 71 Dye solution (contains 25% dye) 5 Pigment dispersant (100% solids) 7

[0050] Example 6 Ink of Example 6 was prepared in the same manner as in Example 5, except that the carbon black was changed to that shown in Table 2.

[0051] (Comparative Examples 1 to 15) Inks of Comparative Examples 1 to 15 were prepared in the same manner as in Example 1, except that the carbon black was changed to that shown in Table 2.

[0052] (Comparative Examples 16 and 17) Inks of Comparative Examples 16 and 17 were prepared in the same manner as in Example 3, except that the carbon black was changed to that shown in Table 2.

[0053] (Comparative Examples 18 and 19) Inks of Comparative Examples 18 and 19 were prepared in the same manner as in Example 5, except that the carbon black was changed to that shown in Table 2.

[0054] (Table 2) TIFF0007825530000002.tif42170 (Ink thixotropy) The thixotropy of the inks prepared in each example and comparative example was evaluated (a value indicating thixotropy was measured) using the following method: Using a cone-plate rotational (coaxial double cylinder) viscometer RotoVisco 1 manufactured by Thermo Fisher Scientific Co., Ltd., the shear stress of the ink was measured at 25°C while the shear rate was increased at a constant rate from 0 (1 / s) to 600 (1 / s) over three minutes (hereinafter referred to as "accelerated shear stress"). The shear stress of the ink was then measured for 10 minutes with the shear rate fixed at 600 (1 / s). Finally, the shear stress of the ink was measured while the shear rate was decreased at a constant rate from 600 (1 / s) to 0 (1 / s) over one minute (hereinafter referred to as "decelerated shear stress"). Next, a graph showing the measurement results was created with shear rate (1 / s) on the X axis and shear stress (Pa) on the Y axis. The value obtained by integrating the curve showing shear stress during acceleration from a shear rate of 0 (1 / s) to 600 (1 / s) minus the value obtained by integrating the shear stress during deceleration from a shear rate of 0 (1 / s) to 600 (1 / s) was taken as the value indicating thixotropy (Pa / s). The measurement results are shown in Table 3.

[0055] (ink viscosity) The ink viscosity of the inks prepared in each of the Examples and Comparative Examples was measured using the following method. When measuring the thixotropy value, the shear rate was fixed at 600 (1 / s) and the shear stress of the ink was measured for 10 minutes. The shear stress after 10 minutes was measured and divided by the shear rate (600 (1 / s)) to determine the viscosity of the ink. The measurement results are shown in Table 3.

[0056] (Ink ribbon production) Next, the inks obtained in each of the examples and comparative examples were applied to a sheet of paper having a width of 13 mm, a length of 25 m, and a basis weight of 64 g / m 2 (Thickness approx. 122 μm) nylon 66 fabric with 14 g / m 2 Next, both ends of the ink ribbon of each example and comparative example were joined by ultrasonic welding to prepare an ink ribbon loop of each example and comparative example.

[0057] (Printing test) The ink ribbon loops of each Example and Comparative Example were loaded into a designated ribbon cassette, and a printing test was carried out in which a designated print pattern was continuously printed using a designated impact printer. The printing was carried out on white continuous slip paper using a 24-pin wire dot printer.

[0058] (print density measurement) Using a Sakata Inx Corporation MR-12 densitometer and a B filter, print density was measured for each example and comparative example. From the start of printing until print density fell below 0.35, print density was measured every 50,000 characters, and the final number of printed characters with a print density of 0.35 or higher was taken as the measurement result (print life). The evaluation results are shown in Table 3.

[0059] (Table 3) As shown in Tables 1, 2, and 3, the volatile content is 7.0% or more and 8.5% or less, and the DBP absorption is 60 cm 3 / 100g or more 78cm 3 / 100g or less, and nitrogen adsorption specific surface area is 300m 2 / g or more 390m 2The ink ribbons of Examples 1 and 2, which use carbon blacks A and B satisfying the following three requirements (hereinafter referred to as the three carbon black properties), have ink viscosities similar to those of Examples 1 and 2 (600-700 mPa m), but have a print life that is 200,000 to 400,000 characters longer than those of Comparative Examples 1 to 15, which use carbon blacks C to Q that do not satisfy at least one of the three carbon black properties. Furthermore, the ink ribbons of Examples 3 and 4, which use carbon blacks A and B that satisfy the three carbon black properties, have ink viscosities similar to those of Examples 3 and 4 (3300-3400 mPa m), but have a print life that is 200,000 characters longer than those of Comparative Examples 16 and 17, which use carbon blacks C and D that do not satisfy at least one of the three carbon black properties. Furthermore, the ink ribbons of Examples 5 and 6, which used carbon blacks A and B that satisfied the three carbon black properties, had ink viscosities similar to those of Examples 5 and 6 (320-330 mPa m), but had print life 300,000 characters longer than those of Comparative Examples 18 and 19, which used carbon blacks C and D that did not satisfy at least one of the three carbon black properties. As mentioned above, the print life of an ink ribbon is affected by the length of the ink ribbon, the printer's running speed, ink viscosity, etc., but under the same conditions, using carbon black that satisfied the three properties above as a pigment made it possible to obtain an ink ribbon with a longer print life than conventional ink ribbons.

Claims

1. The ink is used for an ink ribbon that holds ink on a ribbon fabric made of fibers, and contains carbon black as a coloring pigment, and the carbon black has a volatile content of 7.0% or more and 8.5% or less, and a DBP absorption of 60 cm ３ / 100g or more 78cm ３ / 100g or less, and the nitrogen adsorption specific surface area is 300m 2 / g or more 390m 2 / g or less.

2. 10. An ink ribbon comprising a ribbon material made of fibers and holding the ink according to claim 1.

Images