JPH093381A - Ink composition for fabric ink ribbon - Google Patents

Abstract

PURPOSE: To obtain an ink composition for the fabric ink ribbon of an impact dot printer, by the use of which the corrosion of dot pins can be prevented, their wear can be reduced, and the optical read of an image in the near-infrared region can be improved by using a pigment based on alkaline aniline black as the pigment of the ink. CONSTITUTION: The alkaline aniline black (hereinbelow referred to as A) can be obtained by treating common aniline black with a basic compound. Its pH is desirably in the range of 7.5-10. When the colorant entirely consists of a pigment, the content of the pigment in the ink composition is desirably in the range of 15-30wt.% and the components A desirably amounts to at least 50% of the pigment. When the colorant consists of a pigment and a dye, their contents are desirably 5-25wt.% and 5-20wt.%, based on the ink composition. In this case, the component A desirably amounts to at least 50% of the dye. The fabric used is one having a basis weight of 30-80g/m<2> , and this is impregnated with 5-25g/m<2> of the ink composition.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an ink composition for a cloth ink ribbon used in an impact dot printer.

[0002]

2. Description of the Related Art There are various types of image forming apparatuses for computers, word processors, etc., but impact dot printers are also widely used because of their low cost and the ability to copy the obtained printed matter.

As the ink for the cloth ink ribbon used in such an impact dot printer, as a coloring agent,
Pigments such as carbon black and aniline black, or dyes are used.

[0004]

In recent years, in order to achieve high-speed printing and high quality printing, lightweight iron-based pins used as dot pins and having a thin pin diameter of about 0.2 mm are used. Is becoming.

However, in the case of the conventional ink containing carbon black as a colorant, the iron-based dot pin has a problem that the pin wear is severe and the life of the print head is remarkably shortened.

In consideration of dot pin wear, it is advantageous to use a soft organic pigment as a colorant, but many organic pigments have almost no light absorption in the near infrared region, and the obtained printed matter can be printed in the near infrared region. Optical character reading device (OC) that optically reads with light (usually infrared light with a wavelength of about 900 nm)
There is a problem that reading in R) is difficult.

The present inventors have studied organic pigments having a large absorption intensity in the near infrared region, and have found that aniline black serves this purpose.

However, when aniline black was used, it was often the case that the pin abrasion was severe even though it was a soft organic pigment.

In view of the above points, the present invention is an ink for a cloth ink ribbon used in an impact dot printer, in which the wear of dot pins is reduced and which can be read in the near infrared region by an optical character reader. It is intended to provide a composition.

[0010]

The present invention relates to an ink composition for a cloth ink ribbon, which uses a pigment or a pigment and a dye as a colorant, which is used in an impact dot printer, and contains alkaline aniline black as a main component. The present invention relates to an ink composition for a cloth ink ribbon, characterized in that

[0011]

ACTION AND EXAMPLES According to the study by the present inventors, ordinary aniline black is acidic due to the manufacturing process, and therefore the ink using aniline black as an coloring agent is acidic, and Toddpin is acidic. It was found that contact with the above ink causes corrosion, resulting in a decrease in strength and, as a result, pin wear becomes extremely severe.

The present invention is based on the above findings, and by using alkaline aniline black as the main component of the pigment, the corrosion and wear of the dot pin are suppressed, and the optical reading in the near infrared region is possible. We have succeeded in developing an ink composition for cloth ink ribbons used in dot printers.

The alkaline aniline black used in the present invention is one in which 5 g of aniline black is added to 100 g of distilled water and the mixture is stirred sufficiently and the supernatant shows alkaline.

Such alkaline aniline black can be obtained by treating ordinary alinine black (usually having a pH of 6 or less) with a basic compound. The treatment is specifically carried out by adding aniline black to an aqueous solution of the basic compound and stirring. An aqueous solution is usually used as the aqueous solution, but alcohols such as methanol and ethanol may be added.
When a strong base is used as the basic compound, it is preferably washed with water after the treatment.

If the alkalinity of the alkaline aniline black is too strong, the dispersibility will be problematic, so weak alkaline is preferred, and a pH range of 7.5 to 10 is particularly preferred.

In the present invention, only a pigment is used as a colorant or a pigment and a dye are used in combination, and alkaline aniline black is used as a main component as the pigment.

As pigments other than alkaline aniline black, organic pigments other than carbon black and acidic aniline black, such as paliogen black and phthalocyanine blue, can be used within a range that does not impair the object of the present invention.

An oil-soluble dye such as nigrosine can be used as the dye.

In the present invention, when only the pigment is used as the colorant, the content of the pigment in the ink composition is 15
The range is preferably -30% (% by weight, the same applies below), and in that case, it is preferable that alkaline aniline black occupies 50% or more of the pigment. When the content of alkaline aniline black is less than the above range, it becomes difficult to optically read an image in the near infrared region.

When a pigment and a dye are used in combination as a colorant, the content of the pigment and the dye in the ink composition is preferably in the range of 5 to 25% and 5 to 20%, respectively. It is preferred that alkaline aniline black occupy at least%. When the amount of the alkaline aniline black pigment is less than the above range, it becomes difficult to optically read an image in the near infrared region.

The ink composition of the present invention contains an oil agent as an essential component other than the colorant.

The oil agent includes an oil agent as a dye dissolving agent, an oil agent as a pigment dispersant, and an oil agent as a viscosity modifier.

As the dye-dissolving agent, for example, one or more higher fatty acids such as isostearic acid and oleic acid, and fatty acid esters such as sorbitan fatty acid ester and polyoxyethylene sorbitan fatty acid ester can be used.

As the pigment dispersant, a general surfactant-based dispersant can be used. Examples thereof include sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitan alkyl ether,
Glycerin fatty acid ester, propylene glycol fatty acid ester, polyethylene glycol fatty acid ester,
One or two of polyoxyethylene alkyl ether, hydrogenated castor oil derivative, polyoxyethylene castor oil, etc.
More than one species can be used.

Examples of the viscosity modifier include rapeseed oil,
Castor oil, vegetable oil such as soybean oil, animal oil such as beef leg oil,
Mineral oil such as motor oil, olefin polymerized oil (eg ethylene hydrocarbon oil, butylene hydrocarbon oil, etc.), diester oil [eg dioctyl phthalate,
Dioctyl sebacate, di (1-ethylpropyl) sebacate, dioctyl azelate, dioctyl adipate, etc.], synthetic oil such as silicone oil (eg, low-viscosity linear dimethyl polysiloxane), and the like. Can be used.

Additives such as preservatives, antifungal agents, antioxidants and resins can be appropriately added to the ink composition of the present invention within a range that does not impair the object of the present invention.

The ink composition of the present invention can be prepared by kneading the above components with a roll mill, a sand mill or the like.

A ribbon cloth for impregnating the ink composition is a woven cloth of fibers such as nylon 6, nylon 66, polyester, silk and cotton, and has a basis weight of 30 to 80 g /
Those having a size of about m ² can be preferably used. The appropriate impregnation amount of the ink composition is usually about 5 to 25 g / m ² .

Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples.

Examples 1 and 2 and Comparative Examples 1 to 4 The materials were mixed according to the formulation shown in Table 1 and kneaded with a three-roll mill to prepare inks.

With respect to each of the obtained inks, the amount of dot pin wear, the readability with an optical character reader (OCR suitability), and the dot pin corrosion degree were evaluated. The results are shown in Table 1.

[Dot pin wear amount] Each ink is 13 m wide
15 g / m ² on nylon 66 fabric with m and basis weight of 65 g / m ^2.
The cloth ink ribbon is obtained by impregnating it with a ratio of 100, and this is used in a 24-pin impact dot printer (dot pin material: high-speed steel, diameter 0.2 mm) to print 100 million dots, and to reduce the amount of dot pin wear. It was measured. The average amount of wear of 24 pins was defined as the amount of dot pin wear (μm). If the dot pin wear amount is 30 μm or less, it is in the practical range.

[OCR Suitability] Each of the ink ribbons described above is used in the 24-pin impact dot printer to print on white continuous paper, a density meter manufactured by Macbeth Co., Macbeth PCM-I.
I, the image density (PCS value) was measured in the visible range (using the A filter) and the near infrared range (using the B filter),
The PCS value difference A-B represented by the following equation was obtained.

A−B = PCS value in visible region−PCS value in near infrared region The smaller the PCS value difference A−B, the better the OCR suitability,
Generally, if the value of AB is within 0.1, it is in the practical range.

[Dot Pin Corrosion Degree] The dot pin is immersed in each ink at 85 ° C. for 76 hours to remove cobalt (Co) (included in the material of the dot pin) and other metal on the surface of the dot pin. The composition ratio (Co / other metal (weight ratio)) was measured before and after the immersion, and the dot pin corrosion degree was determined by the following formula. The composition ratio (Co / other metals) was determined by X-ray spectroscopy.

[0036]

[Equation 1]

When the dot pin corrosion degree is smaller than 1, it means that the corrosion is severe. If the dot pin corrosion rate is 0.8 or more, it is in the practical range.

[0038]

[Table 1]

As is clear from Table 1, in Examples 1 and 2 using the alkaline aniline black, the dot pin was less worn and corroded. Also, the OCR suitability is good.

On the other hand, in Comparative Examples 1 and 2 using the acidic aniline black, the dot pins are often worn and corroded.

Comparative Examples 3 to 4 using carbon black
Then, since the carbon black is hard, the wear of the dot pin is remarkable.

[0042]

EFFECTS OF THE INVENTION In an ink composition for a cloth ink ribbon used in an impact dot printer, by using alkaline aniline black as a colorant, corrosion of dot pins is prevented, and wear of dot pins is reduced, Good optical reading in the near infrared region of the obtained printed image.

Claims (1)

[Claims] 1. An ink composition for a cloth ink ribbon, which uses a pigment or a pigment and a dye as a colorant, which is used in an impact dot printer, and which contains alkaline aniline black as a main component as the pigment. Ink composition for cloth ink ribbon.