JPS60198251A - 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 color recording liquids specified in moisture content and having different colors into small liquid droplets and adhering said liquid droplets to a material to be recorded wherein a substrate is provided with a layer to be recorded having cracks with indefinite shapes present therein. CONSTITUTION:In performing ink jet recording by using a plurality of primary color recording liquids, plural kinds of color recording liquids, which have different colors and of which the moisture content is adjusted to 20-90wt%, are 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 film 3 partitioned by cracks 4 having indefinite shapes arranged thereto in a state closely contacted to each other, to form a sharp color image having 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. Related to inkjet recording methods [Prior art] Inkjet recording methods include 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 applies mechanical vibration or displacement to the recording liquid using a piezoelectric element). This method generates small droplets of recording liquid (ink) and makes them fly, and some or all of them adhere to a recording material such as paper to record. However, it is attracting attention as a recording method that generates little noise and can perform high-speed printing and multicolor 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.

Formation of a color image by the inkjet recording method is carried out by a so-called subtractive color mixing method in which image formation is performed using a plurality of primary color recording liquids. In this case, the three primary colors cyan (C), magenta CM)Q, 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) C1M+Y+K (Black) Therefore, the colors represented by the three primary colors C, M, and Y are basically C, M, Y, R, and G.

There are seven colors, B and K, and a multicolor image made up 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 to: 1) ensure that the recording liquid is quickly absorbed into the recording material and that it has different colors; 2) Even if ink dots 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 fall onto the recording material. 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 has a large contrast with the ink dots. 6) The color of the recording liquid does not change depending on the recording material. 7) Dimensional fluctuations of the recording material (e.g. wrinkles, spread) ) must be small before and after recording.

However, in order to satisfy these requirements, conventionally, a great deal depends on the characteristics of the recording material and recording liquid used.
Although it is understood that this is a large number, in reality, an inkjet recording method that meets the various demands for slanting has not yet been found.

For example, if we consider the relationship between the recording material and the recording liquid, we can see that inkjet recording is performed using a normal recording liquid (with a moisture content of about 70%) on high-quality paper used as primary paper. If this is done, the ink absorbency will be poor, the degree of bleeding will be uneven, and the shape of the dont will deteriorate significantly. A recording liquid with a low water content (50% water content) for this paper.
% or less), ink absorption is improved to some extent, but dot shape and color properties are deteriorated. Furthermore, when inkjet recording is performed on commercially available non-coated paper, the ink absorbency exhibits sufficient properties regardless of the water content, but there is large bleeding and the dot shape and color properties are poor. Furthermore, when performing inkjet recording on coated paper for printing, if a recording liquid with a high water content (70% or more of water) is used, the dot shape and bleeding are good, but the dot density is low. Ink absorption is very poor. On the other hand, a recording liquid with a low water content (50% water or less) has good ink absorption, but has large bleeding and low dot density.

[Purpose 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 tilting. 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 new color inkjet recording method that can exhibit excellent recording characteristics even when color recording liquids with a wide range of water contents are used. Another object of the present invention is to prevent changes in environmental temperature during recording.
It is an object of the present invention to provide a color inkjet recording method that can always obtain constant recording image quality.

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 having different colors, 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 has a water content of 20 to 90%. It is characterized by being within the range of % by weight.

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 body made of a porous material such as paper or III or a non-porous material such as a glass plate or resin film. >+ is desirable, but which one is selected 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 film-forming 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)), diatomaceous earth, synthetic mica (general formula: MMg2.(Si401)
o) F2, where M is a hydrogen atom or a gold N 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 singly or in combination, for coating. Make paint.

As the resin suitable for use in this paint, any water-soluble or solvent-soluble resin can be used. For example, water-soluble resins include polyvinyl alcohol, starch, casein, gum arabic, SBR, and gelatin. , polyacrylamide, carboxymethylcellulose, polyacrylic soda, etc., and solvent-soluble resins include polyvinyl butyral, polyvinyl chloride, polyvinyl acetate, polyacrylonitrile, polymethyl methacrylate, polyvinyl formal, melamine resin, polyamide, and phenolic resin. , polyurethane, alkyd resin, etc. 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 5 to 20 parts by weight per 100 parts by weight of the inorganic pigment particles.

The coating layer 2 is formed on the substrate 1 by a known method (for example, a roll coating method, a rot bar coating method, a spray coating method, an air knife coating method), and generally has a coating layer of Ig/m' to 10 g/rrf.
Apply a moderate amount of paint.

Practically speaking, it is preferable to apply the coating at a rate of about 2 g/nf to 5 g/rn'. After such a coating layer is provided, the coating layer is dried as soon as possible. Most of the cover layer 2 produced in this manner is partially enlarged in FIG.
The fine scale-like coatings (dye-trapping portions) 3 partitioned by (reaching the surface of The size of these three scale-like coatings is not particularly limited, but is generally about 10 μs x 10 tiles to several hundred squares x several hundred scales, and the width of the crack 4 is also particularly limited. Although not limited, it is usually about several microns. 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 dye in the ink is almost the same as on the recording paper. Further, since the solvent in the ink quickly migrates to the underlying substrate side through the cracks, an apparently dry state can be quickly obtained on the surface of the recording paper. 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, it is preferable to avoid these IEs.

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. As the liquid medium component of the color recording liquid, a mixture of water and various water-soluble organic solvents is used, and the water content in each color recording liquid is within the range of 30 to 90% by weight. It will be adjusted so that If the water content in the color recording liquid exceeds 90% by weight, even if the above-mentioned recording material is used, the affinity of the recording liquid to the surface of the recording material will be insufficient, and the absorbency of the recording liquid will decrease. This causes the recording liquid to take longer to fix, which limits the recording speed, and when recording liquids overlap, different color recording liquids may mix, and ink dots may become unnecessarily enlarged or disordered. Therefore, it is not appropriate.

In addition, such color recording liquids have problems in terms of ejection stability and dissolution stability of the recording agent, and are not suitable. Further, if the water content in the color recording liquid is less than 20% by weight, even if the above-mentioned recording material is used, the color property, bleeding, and dot shape will be insufficient, so it is not suitable.

Examples of the above-mentioned water-soluble organic solvents include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, and 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; Alkylene glycols containing ~6 carbon atoms: Glycerin; lower alkaline alcohols of polyhydric alcohols such as ethylene glycol methyl ether, diethylene glycol methyl (or ethyl) ether, and triethylene glycol monomethyl (or ethyl) ether; many of these water-soluble Among the organic solvents, preferred are polyhydric alcohols such as diethylene glycol and lower alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl (or ethyl) ether. 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 solubilizing agents are nitrogen-containing heterocyclic ketones, and their intended action is to dramatically improve the solubility of recording agents in liquid media.

For example, N-methyl-2-pyrrolidone and 1,3-dimethyl-2-imidazolidinone are preferably used, and a color recording liquid prepared from such components has recording properties (No. 46 response, liquid Stability of droplet formation, ejection stability, long-term continuous recording performance, ejection stability after long-term recording cessation)
Although it has excellent storage stability and fixability to recording materials, it may further contain various additives in order to further improve these properties. 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 inkjet recording of a type 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 spot within a short period of time, there is no phenomenon of recording liquid flowing out or seeping out, and high-resolution, clear, and excellent color development can be achieved. A color image is obtained. Moreover, the recording liquid ejection method,
Even if a wide variety of recording liquids are used depending on the recording purpose, these excellent characteristics can always be exhibited, making this inkjet recording method a leading 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. After dispersing and dissolving 100 parts by weight of 100 parts by weight of polyvinyl alcohol and 20 parts by weight of polyvinyl alcohol in 500 parts by weight of water, the mixture was 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 80 g/rn') with a sizing degree of 35 seconds based on JIS P8122 at a dry coating weight of 4 g/m'. Next, this was dried by exposing it to hot air at 180°C for 2 seconds to produce a recording material. 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 diatom (Celite White Mist, trade name, manufactured by Jeongmanpil, average particle size: 5.5μ) 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 fl 15 g/rn') with a sizing degree of 35 seconds based on JIS P8122 so that the dry coating amount was 4 g/m'. Next, this was exposed to hot air at 110°C for 1 minute (Production Example 2), 9
Each was exposed to hot air at 0° 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.

Commercially available art coated paper (product name: SK
Approximately 150% of the coating layer surface
A scanning electron micrograph at 0x magnification was as shown in FIG.

Example 1 Primary color recording liquids having the following compositions were used on the recording material produced in Production Example 1, and thermal energy was applied to the recording liquid in the recording head to generate droplets for recording. Full-color ink jet recording was performed by supplying the ink to a recording apparatus having an on-demand type multi-head (discharge orifice diameter 35 mm, heating resistor resistance value 150 Ω, drive voltage 30 V, frequency 2 KHz).

Yellow ink (composition) C, 1, acid yellow 23 2 parts by weight diethylene glycol 3Q tt water 7Q // Magenta ink (composition) C, 1, acid red 82 2 parts by weight wood 70 l
/ Cyan ink (composition) G, 1. Direct Blue 86 2 Parts by weight Diethylene glycol 3Q tt 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 7 On-demand inkjet recording head (discharge orifice diameter: 50 units, piezoelectric vibrator drive pressure), which discharges recording liquid using a piezo vibrator using the following six types of ink onto the recording material produced in Production Example 1. BOV, frequency 4
Inkjet recording was performed using a recording device having a high frequency (KHz), and the recording characteristics were evaluated.

Ink No. A (Composition) Glycerin 8 parts by weight Water 90 // C, 1, Direct Blue 8B 2 tr Ink No.
, B (composition) Glycerin 28 parts by weight Water 7Q /I C,1, Tyleftpur-8B2// Ink No. C (composition) Ethylene glycol 48 parts by weight Water 5o l/ C,1, Direct Blue 8F (2//Ink No,
D (Composition) Diethylene glycol 20 parts by weight N-Methyl-2-pyrrolidone 201/Ethyl cellosolve 2811 Water 3Q tt C,1, Direct Blue 813 2 //Ink N
o, E (composition) Diethylene glycol 10 parts by weight N-methyl-2-pyrrolidone 301/Ethyl cellosolve 38 tt Water 20 tt C, 1, Direct Blue 882// Ink No. F (composition) Diethylene glycol 10 parts by weight N-methyl-2 - Pyrrolidone 40/l Ethyl Cellosolve 38// Water 10 l/ C, L Direct Blue 86 2 Table 1 shows the evaluation results of the recording properties of the recording material.

Each evaluation item in Table 1 was measured according to the following method.

(2) Dot density was measured using a Sakura microdensitometer PDM-5 (manufactured by Konishiroku Photo Industries, Ltd.) of the printed dots.

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

3) #Depth is determined by measuring the diameter of a printed dot using a stereomicroscope and indicating how many times larger it is than the ink drop left.

4) Color vividness was ranked as O, O1Δ, and X, with the color of the inkjet recorded image marked as ■ and the worst as ×.

5) Ink absorption is measured 1 second after printing 3 dots,
If there was no ink flowing out on the surface of the recording material and the image was clear, it was rated 0, otherwise it was rated x.

Reference Examples 8 to 31 Using the recording material prepared in Production Example 2.3, the recording material of Reference Example 1, and commercially available non-coated paper (trade name: Inkjet Recording Paper M, manufactured by Mitsubishi Paper Mills), Reference Example 2 was prepared. The results of evaluating the recording characteristics using six types of inks in the same manner as in ~7 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: non-coated paper).

Examples 2, 3 and Comparative Example 1 Ink No., A used in Reference Example 2 (moisture content: 9
0 weight ink), Ink No. C used in Reference Example 4
(Ink with water content of 50 weight), Ink of reference example)
For each dye, C91, Acid Yellow 23 or C was used instead of C,1, Direct Blue 86.
Yellow ink and magenta ink having different water contents were prepared using the same amount of Acid Red 82. These three sets of primary color recording liquids with different water contents are separately supplied to the inkjet recording apparatus used in the above reference example, and color inkjet recording is performed using the recording material prepared in Production Example 2. was carried out.

A color image formed using a primary color recording liquid with a water content of 90 weight (Example 2) and a water content of 50 weight
Regarding the color image (Example 3) formed using a heavy primary color recording liquid, a color image almost the same as that of Example 1 could be formed.

On the other hand, the color image formed using the primary color recording liquid with a water content of 10 weight (Comparative Example 1) had a rather large degree of bleeding, so the image as a whole lacked sharpness.

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, 1 is a substrate, 2 is a coating layer, 3 is a scale-like coating (dye trapping part), and 4 is a crack. Patent Applicant Canon Co., Ltd. Figure 1 Processor fjJE Letter (Method) April 23, 1985 Commissioner of the Patent Office Mr. Small Case Indication 1988 Patent Application No. 157898
No. 2, Name of the invention Inkjet recording method 3, Relationship with the person making the amendment Applicant: Canon Co., Ltd. 4, Agent address: No. 16 Kowa Building, 8th floor, 5, 9-20 Akasaka, Minato-ku, Tokyo, Amendment Order H March 26, 1985: Date of dispatch 6, subject of amendment 7, -? ltj Correct Contents (1) The description ``indicating the shape and arrangement of filler particles'' is added after the description ``on the surface'' on page 28, lines 4-5 of the specification. (2) Add the statement "indicating the shape and arrangement of filler particles" after the statement "on the surface" on page 28, line 6 of the specification. (3) The description of ``photograph substituted for drawing'' in Mei 1, page 28, line 7 is corrected to ``description of photograph j substituted for drawing.''

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 one in which a coating layer is provided on a substrate, this coating layer has irregularly shaped cracks, and the recording liquid has a moisture content in the range of 20 to 80% by weight. An inkjet recording method characterized by: