JPH03167271A - Method for recording picture image - Google Patents

Abstract

PURPOSE:To prevent floating and enable a high-density. and high-gloss printing by specifying the ratio of the amt. of solvent penetrated into a material being printed to the amt. of total solvent contained in a liq. ink printed when the material is printed with the ink contg. water, a colorant, and a binder. CONSTITUTION:Water, 0.5-10wt.% colorant comprising a dye or pigment, a binder comprising resin particles which are stable in water or a water-sol. org. solvent and have a mean diameter of 5mmu-0.1mum, and, if necessary, a water- sol. org. solvent, a dispersant, a surfactant, a viscosity modifier, etc., are compounded to give a liq. ink which has a viscosity (20 deg.C) of 1.2-10cP and a ratio of the amt. of solvent penetrated into a material being printed to the amt. of total solvent contained in the ink printed of 0.5 or lower. The ink is used as a picture image-printing ink in a printing apparatus which carries out image recording with a liq. ink.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a printing device that records images using liquid ink, and is capable of high-speed, high-quality monochrome and color recording for use in business or personal fields in particular. ,
The present invention relates to an image recording method using an image recording ink that is free from clogging and has excellent storage stability.

[Prior Art] Conventionally, inkjet recording methods can be roughly divided into two types: continuous type and on-demand type. The former is charge control type (Hertz method), and the latter is electromechanical conversion type (Kyser type). method), electrothermal conversion method (
There are two types: bubble jet, thermal ink jet) and electrostatic suction type (slit jet, electric field control type).

Further, as an ink mist recording method, there is a method in which recording ink is atomized using ultrasonic energy, a charge is given to the generated atomized ink, and a charged ink mist is electrostatically recorded on paper.

The inks used in such jet recording methods mainly include water-based inks and non-aqueous inks, but water-based inks are the mainstream in terms of odor, safety, and bleeding.

Water-based inks are currently used in which various water-soluble dyes or pigments are dissolved or dispersed in water or a liquid medium consisting of water and a water-soluble organic solvent, and various additives are added as necessary.

Advantages of jet recording include: - Easy process because it is direct recording - No sound - Easy color conversion - High-speed recording possible - Low running costs because plain paper can be used - High resolution because it uses minute ink Its future potential has been attracting attention for some time, as it has features that exceed the records possible.

In recent years, it is thought that the era of full-scale commercialization of jet printers having the above characteristics as printers for office equipment such as personal computers has arrived.

However, as a product, it is still at the beginning of its growth phase, and there are currently many technical issues that need to be resolved.

Although the requirements for the above recording methods differ slightly depending on the method, the common requirements are 1) the ability to obtain high-quality recorded images without bleeding, and 2) fast ink drying and fixing speeds. No trailing 3) Stable ejection without clogging in the nozzle and ink distribution path 4) Good dispersion stability, storage stability, and safety of the ink 5) High recording density 6) Printed matter It is especially important that the material has good weather resistance.

At present, in order to satisfy all of the above-mentioned requirements, intensive studies are being made from both aspects of recording inks and devices, and considerable improvements have been recognized depending on the required performance.

However, the biggest factor hindering its widespread use is the plain paper commonly used in offices and homes (in Japan, for copying purposes! In other countries, copy paper and pound paper are called plain paper). However, printing quality and image quality are poor. (Therefore, as a last resort, designated paper is prepared.) In other words, when the image forming ink adheres to the recording paper, it has poor drying properties, and as shown in Figure 1, the image forming ink adheres to the recording paper, and as shown in Fig. Because the ink flows, the quality of print and images deteriorates significantly. Therefore, there is a strong desire for an image forming ink that has improved these drawbacks.

From this point of view, various inks for recording on plain paper have been proposed.

For example, in Patent Application Publication No. 55-29546,
It has been proposed to add a specific surfactant to lower the surface tension and increase the absorption of ink into paper. A method of controlling dot spread and absorbency by chemically dissolving sizing agents and pulp materials, which are water-resistant treatment agents for plain paper, using PH (Beher), and a patent application published in 1982-1
Japanese Patent No. 3675 proposes a method in which polyvinylpyrrolidone with a molecular fi of 40,000 or more is added to ink to control dot spread and absorption into paper.

[Problems to be Solved by the Invention] However, such conventional proposals have the following problems.

When printing at high speed on plain paper, each has a certain effect, but with ink containing an interfacial binding agent, the fixing speed is faster because a large amount of ink penetrates, but the surface tension is low, so However, the diffusion of ink along the laH of the paper is not improved and bleeding occurs, resulting in a decrease in density and deterioration of print quality. Furthermore, since foaming occurs due to the surfactant, air bubbles tend to enter the nozzle, resulting in problems such as difficulty in obtaining stable discharge.

In addition, with ink containing strong basic substances, the absorbency of the ink
Although the fixing properties are high, the drying properties are not sufficient, and there are problems in that trailing and ink diffusion along the 1a fibers of the paper are not improved, causing bleeding, and satisfactory print quality cannot be obtained.

In addition, ink containing polyvinyl pyrrolidone with a molecular f40,000 or higher has a very low margin against nozzle clogging, cannot sufficiently improve bleeding, and has poor drying properties that cause trailing. there were.

As described above, it has been found that the above conditions 1) to 6) cannot be satisfied with ink having a high penetration dependence on plain paper.

Therefore, the present invention aims to solve these problems.
A first object of the present invention is to provide an image recording method that enables high-density, high-gloss printing on plain paper with no bleeding of characters or images in a printing device that records images using liquid ink. There is a particular thing.

A second object of the present invention is to provide an image recording method that has fast drying and fixing properties, is free from trailing, and enables full-color recording at high speed and by overlapping process colors.

A third object of the present invention is to provide an image recording method that has excellent ejection stability and does not cause clogging in the nozzle or ink flow path.

A fourth object of the present invention is to provide an image recording method with excellent water resistance and weather resistance.

[Means for Solving the Problems] In the image recording method of the present invention, the constituent components of an image recording ink used in a printing device that records an image using liquid ink are at least water, a colorant, and a fixing agent, and the ink If the permeation rate of the solvent into the transfer medium in a certain portion of the total solvent when it adheres to the transfer medium is defined as X, it is characterized in that X≦50 (%).

[Example] In order for the image recording ink to dry and fix quickly and sufficiently on paper, the present inventor has developed a system in which the constituent components of the image recording ink are fixed in a dispersion medium consisting of at least water, a colorant, and a fixing agent. By optimizing the two factors of solvent evaporation and solvent penetration using a fluid in which resin particles as an agent are dispersed, it is possible to achieve no smearing, fast drying and fixing, excellent ejection stability, and excellent print quality. It was discovered that this material can be made water and weather resistant.

In other words, by dispersing resin particles in image recording ink, as shown in Figure 2, by adhering the coloring agent (dye/pigment) to the paper while adsorbing the coloring agent (dye/pigment) on the surface of these particles, it is possible to form a colorant onto the paper fibers. The problem of bleeding was solved by forming a film while maintaining the dot shape, drying and fixing it.

The resin particles used as a fixing agent in the present invention may be of any type as long as they are stable in water or a water-soluble organic solvent, and include: 1) Acrylic acid ester compounds methyl acrylate, ethyl acrylate butyl acrylate, dodecyl acrylate 2) Methacrylic acid ester compounds methyl methacrylate, ethyl methacrylate, butyl methacrylate 3) Vinyl ester compounds Vinyl acetate 4) Homopolymerized and copolymerized resins such as styrene compounds are preferred, but are not limited thereto. For storage stability and prevention of clogging, the average particle size of the resin particles is preferably in a colloidal state of 5 mm to 0.1 μm.

In order to quickly dry and fix, the amount of the solvent adhering to the transfer medium that permeates into the transfer medium must be 50% or less of the total solvent component.

If the penetration rate is higher than 50%, the drying speed, image quality (density,
This causes problems with gloss, hue, etc.). Distilled pure water is preferable as the solvent used to adjust the permeability, and thermal means such as hot air or a heater can also be used as the adjustment method.

Examples of the solvent used include glycerin, ethylene glycol, propylene glycol, diethylene glycol, polyethylene glycol, triethanolamine, and N-methyl 2-pyrrolidone, which also have an anti-clogging effect. These water-soluble organic solvents can be used alone, but in order to impart appropriate physical properties to the ink, two or more types of solvents can also be used in combination.

Additionally, surfactants can be added to reduce surface tension and viscosity to control penetration, and another method is to optimize the amount of ink adhesion and flight speed.

As the colorant used in the present invention, any water-soluble dye, organic pigment, or inorganic pigment used in conventional inks can be used as long as it does not change the color tone or form a precipitate when added to other ink components. It can also be used with dyes and pigments.

in particular, [Black dye] Direct black #19 (C.I.35255) Direct black #154 Hood black #2 (C.I.27755) [Yellow dye] Acid yellow #23 (C. I. 19140) [Magenta dye] acid led (C. I. 453 acid led (C. I. 451 #8 7 SO) ＃　1　0　6 00) [Cyan dye] Ashid Blue #9 (C.I.42090) Direct Blue #86 (C.I.74180) etc.

Further, as the pigment, a finely dispersed ordinary organic/inorganic pigment is used, and a finely divided pigment having a particle size of 0.1 μm or less is preferable.

The amount of dye/pigment added is preferably between 0.5% and 10% by weight, because if it is less than 0.5% by weight, sufficient color tone and density cannot be obtained, and if it exceeds 10% by weight, clogging tends to occur. .

The physical properties of the ink to achieve the present invention are as follows:
In high-speed printing, if the viscosity is lower than 1.2Cp,
It is preferable to use 1.2 to 10 Cp because it causes problems in drying properties, and if it is larger than 10 cp, it causes clogging and problems in ejection stability.

The basic structure of the present invention is as described above, but in addition, conventionally known dispersants, surfactants, viscosity modifiers, surface tension modifiers, resistivity modifiers, pH modifiers, antifungal agents, etc. are required. It can be added accordingly.

Further, when used in an inkjet system in which ink is ejected by the action of thermal energy, thermal properties (eg, specific heat, coefficient of thermal expansion, thermal conductivity, etc.) are adjusted.

Hereinafter, the present invention will be specifically explained by giving Examples and Comparative Examples, but these Examples do not limit the present invention.

Example 1 All ink composition amounts (%) shown in the following examples are weight %.

Direct Black #19 3% Organic Ultrafine Particles (manufactured by Nippon Paint) 90% (solid content concentration 20%) Diethylene glycol 7% Mix and stir the above ingredients thoroughly in a container, and filter through a membrane filter with a bore size of 0.1 μm. Then, a recording ink was prepared.

Example 2 Carpon black (pigment) 5% Organic ultrafine particles (manufactured by Nippon Paint) 85% (solid content concentration 20%) Glycerin 10% After mixing and stirring the above components, the ingredients were mixed and stirred in a ball mill until the pigment particle size became 0.1 μm or less. The mixture was dispersed to prepare a recording ink.

Example 3 Direct Black 1154 3% acrylic-styrene emulsion 30% (solid content concentration 40% Dainippon Ink & Chemicals!!) Distilled pure water
57% triethanolamine 10
% The above components were thoroughly mixed and stirred in a container, and filtered through a membrane filter with a bore size of 0.1 μm to prepare a recording ink.

Example 4 Acid Yellow #23 3% Microemulsion 30% (solid content concentration 30%, manufactured by Kao) Glycerin 10% distilled pure water
57% acid red micro emulsion (solid content concentration 30%, glycerin distilled pure water #87 3% 3 0% manufactured by Kao) 1 0% 5 7% acid red micro emulsion (solid content concentration 30% glycerin #9 manufactured by Kao) 3 % 3 0% 1 0% Distilled pure water 57% As a comparative example, inks with different penetration rates were used.

Using the above ink, the recording method is ■ Commercially available on-demand inkjet printer ■ Ejection orifice diameter 50 μm, Viezo oscillator running voltage 50
V, Prototype multi-head with a frequency of 5KHz ■ Charged ink mist method using ultrasonic atomization (ultrasonic vibrator drive frequency 1.5MHz, drive voltage 50V) Evaluation results when high-speed recording was performed using the above three methods Table 1 shows the results of measuring the physical properties of the ink.

*1. Bleeding evaluation: Observation with a microscope at 100x and 400x magnification and visual inspection A = Dots are retained on the fibers without any bleeding along the fibers o: M There is some bleeding along the fibers, but visual inspection Not sure ∆: Slight bleeding is visible with the naked eye ×: Drying/fixing performance evaluation with considerable bleeding and jagged edges Rub it with the edge of the paper after 3 seconds, 6 seconds, and 12 seconds ■: After 3 seconds No trailing O: No trailing after 6 seconds Δ: Trailing after 6 seconds ×: Trailing after 12 seconds *3. Clogging evaluation: Leave without cap at room temperature for 1 month ○: Printable ×: Printable *4. Ink storage properties: Store ink at 40°C for 3 months to remove foreign matter, odor, agglomeration,
Presence of precipitation ○; Absent ×: Yes Recording density Measurement of reflection 0-D value using a Macbeth densitometer 5. Ne* 2. *6. Water resistance evaluation: Soak printed material in water for 5 minutes and observe ink flow 0: None ×: Yes *7. Glossiness evaluation Measurement of 75 degree specular gloss using a digital gloss meter (manufactured by Murakami Color Technology Institute) O: 80 or more Δ: 51 to 79 ×: 50 or less *Recorded on 8.0 HP paper 0: Recordable ×: Recorded As is clear from Table 1, the recording inks of Examples 1 to 4 gave good results in common to each recording method.

Moreover, by overlapping each color of yellow, magenta, and cyan of the recording ink of Example 4, a clear full-color image could be reproduced.

On the other hand, when the penetration rate is high, drying properties are poor, resulting in trailing and bleeding, resulting in a low concentration.

[Effects of the Invention] As explained above, according to the image recording method of the present invention,
It is said to enable high-speed recording, high-density, and clear recording with excellent drying and fixing properties, as well as excellent drying and fixing properties on plain paper, which had been a problem in the past, as well as clogging, ink storage stability, and water resistance of printed materials. have an effect.

Furthermore, by using three process color inks, a high-resolution full-color image can be recorded.

Furthermore, according to the image recording method of the present invention, high-speed, high-quality printing is possible even on OHP paper, which cannot be used with normal jet recording.4.

[Brief explanation of the drawing] FIG. 1 is a schematic diagram showing ink bleeding into paper fibers. Figure 2 shows the ink dot of the present invention. FIG. 1 ・Paper fiber 2 ·ink that's all

Claims (1)

[Claims] (1) The constituent components of an image recording ink used in a printing device that records an image using liquid ink are at least water, a colorant, and a fixing agent, and when the ink adheres to a transfer medium, the total solvent component is An image recording method characterized in that, where X is the penetration rate of a solvent into a transfer medium, X≦50(%).