JPS60198250A - Ink jet recording method - Google Patents

Abstract

PURPOSE:To record a sharp color image with high resolving power at a high absorbing speed of a recording liquid, by forming plural kinds of recording liquids specified in viscosity and having different colors into small liquid droplets and adhering said liquid droplets to a material to be recorded having a layer to be recorded, in which cracks having indefinite shapes are present, provided to the substrate thereof. CONSTITUTION:In performing ink jet recording by using a plurality of primary color recording liquids, plural kinds of color recording liquid having different colors and adjusted to 20cP or less in viscosity at 25 deg.C are used and respectively formed into small liquid droplets which are, in turn, adhered to a material to be recorded wherein a substrate 1 is provided with a coating layer 2 having fine scale like films 3 partitioned by cracks 4 having indefinite shapes two-dimensionally arranged thereto in a state closely contacted to each other, to form a sharp color image with high resolving power to perform objective recording. Furthermore, as the substrate 1, a porous material such as paper or cloth and a non- porous material such as a glass plate or a resin film can be used.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to an inkjet recording method, more specifically, an inkjet recording method using a plurality of primary color recording liquids, which is suitable for forming high-resolution, clear color images. This invention relates to an inkjet recording method.

[Prior art]

The inkjet recording method uses various recording liquid ejection methods (for example, an electrostatic suction method, a method that applies mechanical vibration or displacement to the recording liquid using a piezoelectric element, and a method that uses the pressure of heating the recording liquid to foam it and use the resulting pressure). etc.), small droplets of recording liquid (ink) are generated and flown, and some or all of them adhere to a recording material such as paper to perform recording, but it does not generate noise. It is attracting attention as a recording method that allows high-speed printing and multi-color printing.

Water-based recording liquids are mainly used for inkjet recording due to their safety and printability.
Conventionally, ordinary paper has been generally used as the recording material. When recording using liquid ink, it is generally necessary that the recording liquid does not bleed onto the recording paper and cause the print to become blurry, and that the recording liquid dries as quickly as possible after recording, resulting in unexpected damage. It is desirable not to contaminate the paper surface.

Color images are formed by inkjet recording using a so-called subtractive color mixing method in which images are formed using a plurality of primary color recording liquids. In this case, the three primary colors cyan (C), magenta (M) and yellow (Y) are generally used as the primary color recording liquid. The colors that can be expressed by mixing and recording these color recording liquids on the same pixel are as follows:
Basically, the connotation is as follows.

C+M-B (Blue) C+Y-G (Green) M+Y-R (Red) C+M+Y+K (Black) Therefore, the colors represented by the three primary colors C, M, and Y are basically C, M, Y, R, and G. , B, and K, and a multicolor image composed of these seven colors is called a false color image.

In order to form a color image comparable to silver halide photography using such an inkjet recording method using multiple color recording liquids, it is necessary that: (1) the recording liquid is quickly absorbed into the recording material; 2) Even if ink dots of different colors overlap, the recording liquid deposited later should not mix with the recording liquid deposited earlier, disturb the ink dots, or flow out; 2) The recording liquid droplets should not be recorded. 3) The shape of the ink dot should be close to a perfect circle and the surrounding area should be smooth. 4) The ink dot should have a high concentration and the area around the dot should not be blurred. 5) The color of the recording material is white and the contrast with the ink dots is large; 6) The color of the recording liquid does not change depending on the recording material.

7) It is necessary to satisfy various requirements such as minimal dimensional variation (for example, wrinkles, stretching) of the recording material before and after recording.

However, in the past, it has been understood that in order to satisfy these demands, a great deal depends on the properties of the recording material and recording liquid used. It is still not found.

In other words, if we consider the relationship between the recording material and color recording liquid, for example, inkjet recording on non-coated paper is matched to the use of color recording liquid, which has a rather high viscosity; If the viscosity is 12 cp or more, it is possible to prevent the recording liquid from diffusing in the direction of the paper surface and causing so-called bleeding. However, if the viscosity of the color recording liquid is high, the absorbency of the recording liquid deteriorates, which increases the time it takes to fix the recording liquid, and when there is overlap between color recording liquids, mixing of recording liquids of different colors may occur. , there are disadvantages such as unnecessary enlargement and disturbance of ink dots.

In view of these inconveniences, the use of coated paper has been proposed, but although conventional coated paper can suppress the bleeding of recording liquid, it has low absorbency of recording liquid, and conversely, it is difficult to use color recording liquid with a low viscosity of 2 cp or less. This results in restrictions on the use of recording liquids that exceed this viscosity and have excellent water resistance, ejection stability, recording agent dissolution stability, etc. [Object of the Invention] An object of the present invention is to satisfy all the problems that the prior art could not solve in the technical field of the above-mentioned technology. Particularly, the present invention aims to satisfy the above requirements in recording full-color images using a plurality of color recording liquids using an inkjet recording method.

Another object of the present invention is to provide a novel color inkjet recording method that can exhibit excellent recording characteristics over a wide viscosity range of color recording liquids.

Another object of the present invention is to provide a color inkjet recording method that can always provide constant recorded image quality even when the environmental temperature changes during recording.

The above and other objects are achieved by the invention as follows.

[Disclosure of the invention]

That is, the inkjet recording method of the present invention is an inkjet recording method in which small droplets are formed using a plurality of types of color recording liquids each having one different color, and the small droplets are attached to a recording material to perform recording. In the method, the recording material has a coating layer provided on a substrate, the coating layer has irregularly shaped cracks, and the recording liquid is 25
It is characterized by exhibiting a viscosity of 20 Cp or less at ℃.

First, the recording material used in the method of the present invention will be explained based on the schematic diagram of FIG.

In the figure, l is a porous material such as paper or cloth, or a glass plate,
The substrate is made of a non-porous material such as a resin film, and a porous material is desirable in order to improve absorption of the recording liquid, but which of these materials to select depends on the recording purpose and use. 2 is a coating layer, and this layer mainly functions as a recording liquid receiving layer.

This coating layer 2 is basically composed of a non-toxic resin paint, but various surfactants and porous inorganic particles can also be mixed in the paint. . Such surfactants and porous inorganic particles are components that can increase the absorption and capture rate of pigments (for example, dyes) in the ink in the coating layer 2, and are preferably used actively.

As such a component, a white inorganic pigment that is porous and has ionicity on its particle surface is particularly effectively used.

Specifically, natural zeolite, synthetic zeolite (for example, molecular sieve (manufactured by Union Carbide)), diatomite, synthetic mica (general formula: MMg (Si, 0.

)F2, where M is a hydrogen atom or a metal atom)
etc. can be used.

When manufacturing the recording material used in the method of the present invention, these particles (generally particles from several hundred microns to several microns) are mixed and dispersed in a resin coating, either alone or in combination, for coating. Make paint.

As the resin suitable for use in this paint, any water-soluble or organic solvent-soluble resin can be used. For example, water-soluble resins include polyvinyl alcohol, starch, casein, gum arabic, SDR, gelatin, polyacrylamide, carboxymethylcellulose, and sodium polyacrylate, and organic solvent-soluble resins include polyvinyl butyral, polyvinyl chloride, and polyacetic acid. Examples include vinyl, polyacrylonitrile, polymethyl methacrylate, polyvinyl formal, melamine resin, polyamide, phenol resin, polyurethane, and alkyd resin. As for the mixing ratio of the inorganic pigment particles and the resin component in these paints, it is generally appropriate that the resin component be in the range of 5 to 20 parts by weight per 100 parts by weight of the inorganic pigment particles.

To form the coating layer 2, generally Ig/rrf to 10g/rn is formed on the substrate l by a known method (for example, roll coating method, rod per coating method, spray coating method, air knife coating method).
'Apply a certain amount of paint.

Practically speaking, it is preferable to apply the coating at a rate of about 2 g/rn' to 5 g/rn'. After such a coating layer is provided, the coating layer is dried as soon as possible. The coating layer 2 produced in this way has fine particles divided by a partial enlarged view 2A showing a partial area 2a enlarged approximately 50 times (most of which has reached the surface of the base 1). The scale-like coatings (dye-trapping portions) 3 are closely arranged two-dimensionally. The size of these three scale-like coatings is not particularly limited, but is generally about 10u x 10μ to several hundred grams x several hundred, and the width of the crack 4 is also particularly limited. Although it is not a huge amount, it is usually considered to be around a few. Incidentally, the individual size and shape of the scale-like coating 3,
The width of the cracks 4, etc. can be changed arbitrarily within the above range by adjusting or controlling the composition of the coating material or film forming conditions, especially the drying conditions after coating.

When ink adheres to this coating layer 2, the pigment (for example, dye) in the ink is selectively adsorbed to and captured in the area of the coating 3, while the solvent in the ink passes through the cracks 4 and then is captured. , when a porous material is used as the substrate 1, it is quickly absorbed into the substrate 1. When the above-mentioned recording material is used in this way, the pigment in the ink is almost the same as that of the recording paper. Since the solvent inside quickly migrates to the underlying substrate side through the cracks, the surface of the recording paper can quickly attain an apparently dry state.Furthermore,
The scale-like coating 3 is particularly effective in preventing ink dots from being unnecessarily large, dots having high concentration, and the periphery of the dots from becoming blurred. This is because of intensive adsorption.

The quality of this adsorption ability is determined mainly by the surface physical properties and chemical properties (for example, ionicity) of the coating 3 itself, surfactant, and pigment particles. Therefore,
If the area occupied by the scale-like coating 3 in the coating layer 2 is extremely small, there is a disadvantage that the capture rate of the dye decreases and the color development and density of the dots are reduced.Furthermore, the area occupied by the cracks 4 is extremely large. When this happens, the amount of ink transferred to the substrate increases, resulting in the phenomenon of so-called ink bleed-through, and disadvantages such as deterioration of dot shape are observed. Therefore, these aspects are preferably avoided.

On the other hand, each of the plurality of color recording liquids used in the method of the present invention consists of a recording agent such as a dye and a liquid medium component. Generally, when recording is performed using a recording liquid, it is important to match the liquid physical properties (viscosity, surface tension, etc.) of the recording material and the recording liquid. For example, the absorption speed of ink is inversely proportional to the viscosity of the recording liquid. Furthermore, the diameter of recording liquid droplets tends to become smaller in almost inverse proportion to the viscosity, and the diameter of printed dots tends to become smaller. The degree of change in printing characteristics varies depending on the structure and material of the recording material, and it is therefore important to match the physical properties of the recording material and the color recording liquid.

The liquid medium components of the color recording liquid used in the method of the present invention include not only the water wheel but also the color recording liquid having a viscosity of 2Qcp at 25°C, more preferably 15cp.
, particularly preferably within a range not exceeding 12 cp, and preferably a mixture of water and various water-soluble organic solvents is used. If the viscosity of the color recording liquid at 25° C. exceeds 20 cp, the absorbency of the color recording liquid decreases, the time required for fixing the recording liquid becomes longer, the recording speed is limited, and the color recording liquids overlap each other. This is not suitable because it may cause mixing of different color recording liquids or cause unnecessary enlargement or disturbance of ink dots.

Examples of the water-soluble organic solvent include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, 5ec-
Alkyl alcohols having 1 to 4 carbon atoms such as butyl alcohol, tert-butyl alcohol, and isobutyl alcohol; amides such as dimethylformamide and dimethylacetamide; ketones or ketone alcohols such as acetone and diacetone alcohol; tetrahydrofuran, Ethers such as dioxane; polyalkylene glycols such as polyethylene glycol and polypropylene glycol; Examples include alkylene glycols containing 6 carbon atoms; lower alkyl ethers of polyhydric alcohols such as diethylene glycol methyl (or ethyl) ether and triethylene glycol monomethyl (or ethyl) ether.

Among these many water-soluble organic solvents, polyhydric alcohols such as diethylene glycol and lower alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl (or ethyl) ether are preferred. Polyhydric alcohols are particularly preferred because they are highly effective as wetting agents to prevent nozzle clogging caused by evaporation of water in the color recording liquid and precipitation of recording agent.

In order to adjust the viscosity of the color recording liquid containing such liquid medium components within the above range, a viscosity modifier such as polyvinyl alcohol, cellulose, water-soluble resin, etc. can be added.

A solubilizer can also be added to the color recording liquid. Typical solubilizers include nitrogen-containing heterocyclic ketones, and their purpose and function is to dramatically improve the solubility of the weight agent in static U.

For example, N-methyl-2-pyrrolidone and 1,3-dimethyl-2-imidazolidinone are preferably used.

Color recording liquid prepared from these components has its own recording properties (signal response, droplet formation stability, ejection stability, long-term continuous recording performance, ejection stability after a long recording stop). It is excellent in properties), storage stability, and fixability to recording materials, but in order to further improve these properties, it may further contain various additives. Examples include various cationic, anionic or nonionic surfactants, surface tension regulators such as jetanolamine and triethanolamine; and pH regulators using buffer solutions.

Further, in order to prepare a color recording liquid used in an inkjet recording method of the type in which the recording liquid is charged, a resistivity adjuster such as an inorganic salt such as lithium chloride, ammonium chloride, or sodium chloride is added. Note that when applied to an inkjet system in which recording liquid is ejected by the action of thermal energy, thermal physical property values (eg, specific heat, coefficient of thermal expansion, thermal conductivity, etc.) may be adjusted.

[Effects of the present invention]

According to the method of the present invention, even if different color recording liquids are repeatedly deposited on the same cylinder within a short period of time, there is no outflow or oozing phenomenon of the recording liquid, and high-resolution, clear and excellent color development is achieved. A color image is obtained. Furthermore, even if there are changes in the environmental temperature, these excellent characteristics can be exhibited at all times, making it an excellent inkjet recording method for full-color recording.

〔Example〕

Hereinafter, the method of the present invention will be explained in more detail according to Examples.

Production Example 1 Psil E150. Product name: Nippon Silikani Co., Ltd., average particle diameter: 5u) Too parts by weight and 20 parts by weight of polyvinyl alcohol were dispersed and dissolved in 500 parts by weight of water, and then pulverized and mixed in a ball mill for 12 hours to obtain a slurry. .

This slurry was coated on one side of general high-quality paper (basis weight 60 g/rn') with a sizing degree of 35 seconds based on JIS P8122 to a dry coating amount of 4 g/rn', and then heated at 180°C. A recording material was prepared by drying it by exposing it to hot air for 2 seconds. Approximately 100% of the surface of the coating layer of the obtained recording material
A scanning electron micrograph at 0x magnification is shown in Figure 2.

Production Examples 2 and 3 After dispersing and dissolving 100 parts by weight of diatomaceous material (Celite White Mist, trade name, Johnmanviric acid, average particle size: 5.5%) and 15 parts by weight of sodium alginate in 500 parts by weight of water. The mixture was ground and mixed in a ball mill for 15 hours to obtain a slurry.

This slurry was coated on one side of general high-quality paper (basis weight B5 g/rn') with a sizing degree of 35 seconds based on JIS P8122 to a dry coating amount of 4 g/d. 1 minute in hot air (manufacturing example 2),! Each was exposed to hot air at 30° C. for 30 minutes (Production Example 3) and dried to produce a recording material. Scanning electron micrographs of the surfaces of the coating layers of the obtained recording materials were similar to those shown in FIG. 2, although the sizes of the scale-like coatings were slightly different.

Reference Example 1 Commercially available art coated paper (product name: SK
Approximately 150% of the surface of the coating layer (made by Sanyo Kokusaku Pulp ■)
A scanning electron micrograph at 0x magnification was as shown in FIG.

Example 1 For the recording material produced in Production Example 1, color recording liquids having the following compositions each having a viscosity of 3.5 cp at 25°C were used, and these color recording liquids were applied with thermal energy to the recording liquid in the recording head. On-demand type multi-head (discharge orifice diameter 35μ) that generates droplets and records by applying
, heating resistor resistance value of 150 Ω, drive voltage of 30 V, and frequency of 2 KHz) to perform full-color inkjet recording.

Yellow ink (composition) C, L Acid Yellow 23 2 Parts by weight diethylene glycol 30〃 Water 70〃 Magenta ink (composition) C,1, Acid Red 82 2 Parts by weight diethylene glycol 30〃 Water 70〃 Cyan ink (composition) C,1, Direct Blue 86 2 Parts by weight Diethylene glycol 30 Water 7Q // The recorded images were clear and had the desired color tone, and the dot shape and ink absorption were also good.Reference Examples 2 to 8 An on-demand ink jet recording head (discharge orifice diameter 50#L11, piezo vibrator drive voltage BOY Inkjet recording was performed using a recording device having a frequency of 4 KHz), and the recording characteristics were evaluated.

Ink No. A: Ink with a viscosity of approximately 25 cp (set! &
)゛Glycerin 70 parts by weight Water 30 l/Acetinol EHO, 1// (Surfactant, manufactured by Yoken Fine Chemical Co., Ltd.) C, 1, Direct Blue 862// Ink No. B: Ink with a viscosity of approximately 20 cp (composition) Glycerin 65 Parts by weight Water 35 Acetinol EHO, 1/1 c, r, Direct Blue 86 2 Ink No.
C: Ink with a viscosity of about 15 cp (composition) Diethylene glycol 80 parts by weight Water 20 tt Acetinol EHQ, l tt C, 1, Direct Blue 86 2 Ink No.
D: Ink with a viscosity of approximately IQcp (composition) Diethylene glycol 70 parts weight 1 part water 30 Acetinol EHQ, l // C, 1, Direct Blue 86 2 Ink No.
E-: Ink with a viscosity of about 5 cp (composition) Triethylene glycol monomethyl ether 50 parts by weight Water 5Q tt - Acetinol EHQ, l tt c, r, Direct Blue 88 2 tt Ink No.
F: Ink with a viscosity of approximately 3 cp (composition) Ethylene glycol 45 parts by weight Water 55 Acetinol EHQ, L tt C, 1, Direct Blue 86 2 Ink No.
G: Ink with a viscosity of approximately 1.5 cp (composition) Ethylene glycol 70 parts by weight Water 3 o Acetinol El (Q, l tt C, 1, Direct Blue 86 2) Table 1 shows the evaluation results of the recording characteristics of the recording material. show.

Measurement of each evaluation item in Table 1 is performed using the following method.
Table 1) Dot density was measured using a Sakura microdensitometer PDM-5 (manufactured by Konishiroku Photo Industry 2).

2) The dot shape is determined by observing the printed dots with a stereoscopic microscope.
The amorphous one was designated as X.

3) The degree of bleeding was determined by measuring the diameter of a printed dot using a stereomicroscope, and expressed by how many times larger the diameter of the printed dot was than that of an ink droplet.

4) Color clarity was determined by visually comparing the color clarity of the inkjet recorded images, and ranking the best one as ■, the worst as ×, and ranked them as o, O1△, and X.

5) Ink absorption is measured 1 second after printing 3 dots,
When there was no ink flowing out on the surface of the recording material and the image was clear, it was rated as O, otherwise it was rated as ×.

Reference Examples 9 to 36 Using the recording material produced in Production Example 2.3, the recording material of Reference Example 1, and commercially available non-coated paper (trade name: Itsukjet Recording Paper M, manufactured by Mitsubishi Paper Mills), reference examples were prepared. The results of evaluating the recording characteristics using seven types of inks in the same manner as in 2 to 8 are shown in Table 2 (Recorded material: Production example 2) and Table 3 (Recorded material:
Production Example 3), Table 4 (Recorded material: Reference Example 1) and Table 5 (
Recording material: /Noko-1 paper).

Comparative Example 1 and Example 2.3 Ink No. A used in Reference Example 2 (viscosity approximately 25c)
Ink No. p), Ink No. used in Reference Example 4.

C (ink with a viscosity of about 15 cp), Ink No. and E (ink with a viscosity of about 5 cp) used in Reference Example 6, respectively, as dyes C, 1 and Direct Blue 86.
Instead of C,1, Acid Yellow 23 or C,1
Yellow ink and magenta ink having different viscosities were prepared using the same amounts of Acid Red 82 and Acid Red 82, respectively.

These three sets of primary color recording liquids with different viscosities were separately supplied to the inkjet recording device used in the above reference example, and color inkjet recording was performed using the recording material produced in Production Example 2. did.

Regarding the color image (Comparative Example 1) formed using a primary color recording liquid with a viscosity of approximately 25 cp, the image lacked sharpness due to the poor shape of the ink dots.
Because the ink absorption was low, the vividness of the colors was also low.

In contrast, for a color image formed using a primary color recording liquid with a viscosity of approximately 15 cp (Example 2) and a color image formed using a primary color recording liquid with a viscosity of approximately 5 cp (Example 3). Although a color image of almost the same level as that of Example 1 could be formed, Example 3 was found to be slightly superior in color tone reproducibility.

Comparative Example 3 A color image was formed in exactly the same manner as in Example 1, except that the art coated paper of Reference Example 1 was used as the recording material. The obtained color image had low ink absorption of the recording material, and therefore the color clarity of the color image as a whole was low.

Table 1 Table 2 Table-3 Table 4 Table 5

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the structure of the recording material used in the present invention, and FIG. 2 shows approximately the surface of the recording layer of the recording material suitable for use in the method of the present invention. This is a photograph taken in place of a drawing taken with a scanning electron microscope at 1000x magnification. FIG. 3 is a photograph of the surface of a commercially available coated paper taken with a scanning electron microscope at the same magnification and used as a substitute for a drawing. In the figure, l indicates the substrate, 2 indicates the coating layer, 3 indicates the scale-like coating (dye trapping portion), and 4 indicates the crack. Figure 1 Procedural amendment (method) April 23, 1985 Director-General of the Patent Office Mr.■, Indication of case 1981 Patent application No. 157611
? No. 2, Name of the invention Inkjet recording method 3, Relationship with the person making the amendment Applicant: Canon Co., Ltd. 4: Agent address: 1-9-20-5 Akasaka, Minato-ku, Tokyo Date of amendment order: 1985 March 26th: Shipping date 6, "Brief explanation of drawings" column of the specification subject to amendment. 2/-1), 7. Contents of the amendment (1) Added the statement "indicating the shape and arrangement of filler particles" after the statement "on the surface" on page 27, lines 4 to 5 of the specification. do. (2) Add the statement "indicating the shape and arrangement of filler particles" after the statement "on the surface" on page 27, line 8 of the specification.

Claims (1)

[Claims] 1. In a method for forming an inkjet recording method in which small droplets are formed using a plurality of types of color recording liquids having different colors, and the small droplets are attached to a recording material to perform recording, the method described above. The recording material is characterized in that a coating layer is provided on a substrate, the coating layer includes irregularly shaped cracks, and the recording liquid exhibits a viscosity of 20 cp or less at 25°C. Inkjet recording method.