JP2635948C - - Google Patents

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to an ink jet recording method, and more particularly to an improved method of a multicolor ink jet recording method. [0002] Ink jet recording methods include various recording liquid discharge methods (for example, an electrostatic suction method, a method of applying mechanical vibration or displacement to a recording liquid by using a piezoelectric element, and a method of heating a recording liquid. A method of generating small droplets of a recording liquid (ink) by means of foaming and utilizing the pressure), causing them to fly, and attaching a part or all of them to a recording material such as paper for recording. However, it has attracted attention as a recording method that generates less noise and can perform high-speed printing and multicolor printing. As a recording liquid for ink jet recording, an aqueous liquid is mainly used from the viewpoint of safety and printability, while ordinary recording paper is generally used as a recording material. Was. When recording is performed using a liquid recording liquid, it is generally necessary that the recording liquid does not bleed on the recording paper so that the print is not blurred, and that the recording liquid dries as quickly as possible after recording and unexpectedly It is desirable not to contaminate the paper surface. [0004] In particular, in a multi-color ink jet recording system using recording liquids of two or more different colors, 1) when the recording liquid is rapidly absorbed by the recording material and overlapping of different color ink dots occurs. However, the recording liquid that has adhered later does not mix with the recording liquid that has adhered earlier, disturbs the ink dots, or does not flow out. 2) The droplets of the recording liquid diffuse on the recording material, and the ink dots 3) The shape of the ink dot is close to a perfect circle and its periphery is smooth. 4) The density of the ink dot is high and the periphery of the dot does not blur. 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) The dimensional fluctuation (for example, wrinkles and growth) of the recording material is reduced. It is less before and after recording, it is necessary to satisfy various requirements and the like. [0005] However, it has been understood that the characteristics of the recording material and the recording liquid to be used are very much dependent on satisfying these requirements. Has not yet found an inkjet recording method that meets the above-mentioned requirements. That is, for example, when considering the relationship between the recording material and the surface tension of the recording liquid, if ink jet recording is performed using a conventional recording material having a recording layer, the surface of the recording layer will As shown in FIG. 2, since only small voids exist as shown in FIG. 2, when a recording liquid having a high surface tension is used, the penetration of the recording liquid into the voids is hindered, so that the absorption speed of the recording liquid is reduced. Therefore, when a recording liquid having a low surface tension is used to increase the absorption speed, the spread of the recording liquid in the paper surface direction becomes large, as in the case of using non-coated paper, and the contradictory problem that good printing characteristics cannot be obtained. And could not resolve this. An object of the present invention is to satisfy all the problems that the prior art could not solve in the technical field described above. In particular, it is an object of the present invention to satisfy the above-described various requirements in recording a full-color image using a plurality of color recording liquids by an inkjet recording method. Another object of the present invention is to provide a novel ink jet recording method capable of exhibiting excellent recording characteristics in a wide range of surface tension of a recording liquid. [0008] The ink jet recording method of the present invention comprises forming ink droplets, and providing the droplets on a support with a coating layer mainly composed of inorganic pigment particles. In the ink jet recording method of performing recording by attaching to the surface of the coating layer of the recording material, the inorganic pigment particles in the coating layer are silica having a particle diameter in a range of 3 to 20 μm, and the coating layer is formed of silica. And a binder mainly composed of a water-soluble polymer, wherein the mixing ratio of the silica and the binder is in the range of 100/20 to 100/100 by weight, and the dry coating amount is 15 g / m2. ² or more, have a structure in which irregular particle shape of the silica is appeared on the surface, and the range of surface tension 30 to 60 dyn / cm at 20 ° C. of the ink, with the thermal energy to the ink And wherein the generating the droplets to. That is, the recording material used in the method of the present invention comprises a support and a coating layer provided on the support, and the coating layer is provided with droplets of a recording liquid during recording. It has a function as a recording layer to be formed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As a support for a recording material of the present invention, paper is suitably used. However, porous materials such as cloth, porous resin, wood, etc. Non-porous materials such as metal and glass can also be used, and which one to select depends on the purpose of recording and the application. On the other hand, the coating layer is mainly composed of inorganic pigment particles fixed on a support with a water-soluble polymer. Examples of the inorganic pigment particles include white inorganic pigments such as silica, clay, talc, diatomaceous earth, calcium carbonate, calcium sulfate, barium sulfate, titanium oxide, zinc oxide, satin white, aluminum silicate, lithopone, alumina, and zeolite. One or more kinds of particles consisting of In order for the irregular shape of the inorganic pigment particles to appear on the surface of the coating layer as if rubble was scattered, the particle size of the inorganic pigment particles used should be about 3 to 20 μm. If the particle size of the inorganic pigment particles is too large, the roundness of the ink dots is impaired, and the resolution of the recorded image is undesirably reduced. [0013] The inorganic pigment particles contained in the coating layer are preferably those having a high dye-adsorbing property, and more preferably those having a porous structure. This is because the coloring property becomes better when the recording agent such as a dye in the recording liquid is captured on the outermost layer of the coating layer. Examples of the water-soluble polymer as a binder include water-soluble polymers such as starch, gelatin, casein, gum arabic, sodium alginate, carboxymethyl cellulose, polyvinyl alcohol, polyvinyl pyrrolidone, sodium polyacrylate, and polyacrylamide. One or more can be used. A water-soluble polymer may be used alone as a binder component, or other binder components may be used in combination as long as the binder is mainly composed of a water-soluble polymer. Other binder components that can be used in combination with the water-soluble polymer include synthetic resin latex such as synthetic rubber latex, polyvinyl butyral, polyvinyl chloride, polyvinyl acetate, polyacrylonitrile, polymethyl methacrylate, polyvinyl formal, melamine resin, polyamide Examples thereof include resins soluble in organic solvents such as resins, phenolic resins, polyurethane resins, and alkyd resins. If necessary, one or more of these can be used in combination with the above water-soluble polymer. Further, various additives such as a dispersant, a fluorescent dye, a pH adjuster, an antifoaming agent, a lubricant, a preservative, and a surfactant can be mixed in the coating layer. A recording material suitable for use in the method of the present invention includes a coating liquid prepared by dispersing these coating layer forming components in a medium such as water, and a roll coating method, It can be manufactured by coating on a support by a bar coating method, a spray coating method, an air knife coating method, or the like, and then drying as quickly as possible. The mixing ratio between the inorganic pigment particles and the water-soluble polymer in the coating liquid is set to 10
The binder is suitably used in an amount of 20 to 100 parts by weight with respect to 0 parts by weight, and when the average particle size of the inorganic pigment particles is large, it is preferable to use as little binder as possible. The amount of the coating layer on the support is preferably a dry coating amount of 15 g / m ² or more. The upper limit of the dry coating amount is usually about 50 g / m ² , preferably about 30 g / m ² . FIG. 1 is an enlarged view of the surface of a coating layer obtained from a scanning electron micrograph of about 1500 times the recording material suitable for use in the method of the present invention thus produced. The unique surface condition is well illustrated. That is, amorphous inorganic pigment particles having a relatively large particle size, which is a main component of the coating layer, appear on the surface of the coating layer in a state where they are randomly placed, and function as ink absorption holes between the particles. Many large voids are scattered, and so to speak, it has a surface structure that can be described as scattered large and small rubble.
Of course, the inorganic pigment particles appearing on these surfaces are also fixed in the coating layer by the binder, and are not easily separated from the coating layer. The recording liquid used in the method of the present invention comprises a recording agent such as a dye and a liquid medium component. In general, when recording is performed using a recording liquid, it is important to match the properties of the recording material with the liquid properties of the recording liquid. You need to use selective. That is, since the critical surface tension of the recording material is in the range of 40 to 50 dyn / cm, it is preferable to use a recording liquid having a surface tension close to this value. Therefore, the recording liquid used in the method of the present invention is 30 to 60 dyn / cm, preferably 35 to 55 dyn / c at 20 ° C.
m, particularly preferably in the range of 40 to 50 dyn / cm. When printing is performed using a recording liquid having a surface tension lower than this range, the wettability to the recording material is good, but the spread of the printed dots is large. On the other hand, when a recording liquid having a surface tension higher than the upper limit of the above range is used, the wettability to the recording material is deteriorated, and as a result, the absorption of the recording liquid and the dot density are undesirably reduced. As the liquid medium component of the recording liquid used in the method of the present invention, not only water alone but also water and various water-soluble organic solvents are preferable as long as the surface tension of the recording liquid is satisfied. A mixture is used. As the water-soluble organic solvent, for example, methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol,
C1-C4 alkyl alcohols such as n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol and isobutyl alcohol; amides such as dimethylformamide and dimethylacetamide; ketones and ketones such as acetone and diacetone alcohol Alcohols; ethers such as tetrahydrofuran and dioxane; polyalkylene glycols such as polyethylene glycol and polypropylene glycol; ethylene glycol, propylene glycol, 1, 2,
Alkylene glycols having an alkylene group containing 2 to 6 carbon atoms, such as 6-hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol; glycerin; ethylene glycol monomethyl ether, diethylene glyl methyl (or ethyl) ether; And lower alkyl ethers of polyhydric alcohols such as ethylene 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
This is particularly preferable because the effect as a wetting agent for preventing nozzle clogging caused by evaporation of water in the recording liquid and precipitation of the recording agent is large. In order to adjust the surface tension of the recording liquid containing such a liquid medium component within the above range, various surface active agents such as cations, anions or nonionics, and surface tension adjusters such as diethanolamine and triethanolamine Can be added. A solubilizing agent may be added to the recording liquid. Typical solubilizers are nitrogen-containing heterocyclic ketones, the purpose of which is to significantly improve the solubility of the recording agent in a liquid medium. For example, N-methyl-2-pyrrolidone and 1,3-dimethyl-2-imidazolidinone are preferably used. The recording liquid prepared from such components has a recording characteristic (signal responsiveness,
These have excellent droplet formation stability, ejection stability, long-term continuous recording properties, ejection stability after long-term recording suspension), storage stability, and fixability to recording materials. In order to further improve the characteristics of the above, various additives may be further contained. For example, viscosity modifiers such as polyvinyl alcohol, celluloses, and water-soluble resins;
H regulators can be mentioned. In order to apply the present invention to an ink jet system of a type in which a recording liquid is discharged by the action of thermal energy , thermal physical properties (for example, specific heat, thermal expansion coefficient, thermal conductivity, etc.) are sometimes adjusted. According to the method of the present invention, even when recording liquids of different colors adhere to the same place in a short period of time, there is no phenomenon of bleeding out or bleeding out of the recording liquid, and high-resolution clear and excellent color formation. A sex image is obtained. Moreover, even when a recording liquid having a wide range of surface tensions is used depending on the recording liquid ejection method, recording purpose, and the like, these excellent characteristics can always be exhibited, and an inkjet recording method for performing full-color recording. It is excellent. Hereinafter, the method of the present invention will be described in more detail with reference to Examples. Reference Example 1 Silica (Nipsil E150, trade name, manufactured by Nippon Silica Industry Co., Ltd., average particle diameter: 5 μm) was used as inorganic pigment particles, and polyvinyl alcohol and SB were used as binders.
A coating composition was prepared based on the following composition using R latex. Silica 100 parts by weight Polyvinyl alcohol 25 parts by weight SBR latex 5 parts by weight Water 500 parts by weight On the other hand, as a support, general high-quality paper (basis weight 65 g / m ² ) having a size of 35 seconds based on JIS P8122 is used. The coating composition was coated on the support by a blade coater method at a dry coating amount of 15 g / m ² and dried by a conventional method to obtain a recording material. The surface of the coating layer in a scanning electron microscope photograph of the obtained recording material at a magnification of about 1500 was as shown in FIG. An on-demand type ink jet recording head (discharge orifice diameter 50 μm, piezo vibrator drive voltage 60 V, and piezo vibrator) discharges ink to the recording material by using a piezo vibrator using seven types of inks shown in Table 1 below. Inkjet recording was performed using a recording device having a frequency of 4 kHz), and recording characteristics were evaluated. [Table 1] Table 2 shows the evaluation results. The measurement of each evaluation item in Table 2 was performed according to the following method. 1) The dot density is determined by changing the print dots from the Sakura Micro Densidometer PDM-5 (
(Manufactured by Konishi Roku Photo Industry Co., Ltd.). 2) For the dot shape, observe the printed dots with a stereoscopic microscope, and
When the circle was slightly distorted, it was marked with △, and when it was irregular, it was marked with x. 3) The degree of bleeding was measured by measuring the diameter of the printed dot with a stereoscopic microscope, and indicated by the number of times the ink droplet was multiplied. 4) The color clarity is determined by visually comparing the color clarity of the ink jet recorded image,
The best ones were marked with ◎, the worst ones were marked with x, and ◎, △, Δ and × were ranked. (5) The ink absorptivity was evaluated as ○ when the ink did not flow out on the surface of the recording material 1 second after the three-dot overlap printing, and when the image was clear, and was evaluated as x when the image was not. [Table 2] Reference Example 2 A coating composition was prepared based on the following composition using calcium carbonate (average particle diameter: 3 μm) as the inorganic pigment particles and starch and SBR latex as the binder. Calcium carbonate 100 parts by weight Starch 30 parts by weight SBR latex 10 parts by weight Water 300 parts by weight On the other hand, the same general high-quality paper as in Reference Example 1 was used as a support, and the coating composition was coated on the support. The material was applied by a blade coater method at a dry coating amount of 20 g / m ² and dried by a conventional method to obtain a recording material. Table 3 shows the results of evaluating this recording material in the same manner as in Reference Example 1 . [Table 3] Reference Example 3 A coating composition was prepared based on the following composition using talc (average particle diameter: 7 μm) as inorganic pigment particles and casein as a binder. 100 parts by weight of talc 20 parts by weight of casein 500 parts by weight of water On the other hand, the same general high-quality paper as in Reference Example 1 was used as a support, and the coating composition was dried and coated on the support. Coating was performed by a blade coater method at a rate of 20 g / m ² and dried by a conventional method to obtain a recording material. Table 4 shows the results of evaluation of this recording material in the same manner as in Reference Example 1 . [Table 4] Comparative Example 1 A commercially available art-coated paper (trade name: SK Coat, manufactured by Sanyo Kokusaku Pulp Co., Ltd.) was used as a recording material, and the ink jet recording characteristics were evaluated in the same manner as in Reference Example 1 . Table 5 shows the results. The surface of this paper, which was shown in a scanning electron microscope photograph of about 1500 times, was as shown in FIG. [Table 5] Example 1 The surface tension at 20 ° C. of the recording material used in Reference Example 1 was 54 dyn /
cm of ink having the composition shown in Table 6 below, and applying the thermal energy to the ink in the recording head to generate ink droplets to perform on-demand type multi-head recording (ejection orifice diameter 35 μm, heating resistor Resistance value 150Ω, drive voltage 30
V, frequency 2 kHz) to perform full-color ink jet recording. [Table 6] The obtained recorded image was clear and exhibited a predetermined color tone, and had a good dot shape and good ink absorbency. Comparative Example 2 Evaluation of ink jet recording characteristics in the same manner as in Reference Example 1 except that the recording materials formed in Reference Examples 1 to 3 were used and two types of inks having the compositions shown in Table 7 below were used. Was done. The results are shown in Tables 8 to 10. [Table 7] [Table 8] [Table 9] [Table 10] According to the ink jet recording method of the present invention, a recording material comprising inorganic pigment particles as a main component and a coating layer having a unique surface state provided on a support is used. Even if the recording liquid of Example 1 overlaps and adheres to the same portion within a short period of time, the recording liquid does not flow out or bleed out, and a high-resolution clear and excellent color-forming image can be obtained. In addition, even when a recording liquid having a wide range of surface tensions is used according to the recording liquid ejection method, recording purpose, etc., these excellent characteristics can always be exhibited. This is an excellent inkjet recording method for performing recording.

[Brief description of the drawings]     FIG.   FIG. 2 is an enlarged view of the surface of the coating layer of the recording material of the present invention at a magnification of about 1500 times.     FIG. 2   FIG. 3 is an enlarged view of a coating layer surface of a commercially available art-coated paper at a magnification of about 1500 times.

Claims (1)

Claims 1. An ink droplet is formed, and the ink droplet is formed on a surface of a recording material having a coating layer mainly composed of inorganic pigment particles provided on a support. In the inkjet recording method of performing recording by adhering, the inorganic pigment particles in the coating layer are silica having a particle diameter in a range of 3 to 20 μm, and the coating layer is mainly composed of the silica and a water-soluble polymer. A binder containing the silica and the binder in a mixing ratio of 100/20 to 100/100 on a weight basis and a dry coating amount of 15 g / m ² or more; has a particle shape becomes appear on the surface structure and the range surface tension of 30 to 60 dyn / cm at 20 ° C. of the ink, the thermal energy imparted to generate the droplets in the ink A. Ng jet recording method. 2. The method according to claim 1, wherein the water-soluble polymer is selected from starch, gelatin, casein, gum arabic, sodium alginate, carboxymethylcellulose, polyvinyl alcohol, polyvinylpyrrolidone, sodium polyacrylate, and polyacrylamide. Ink jet recording method. 3. The ink jet recording method according to claim 1, wherein the recording is performed by attaching ink droplets of two or more colors to the same location. 4. A surface tension at 20 ° C. of the ink 35 to 55Dyn /
The inkjet recording method according to any one of claims 1 to 3 , which is in a range of 1 cm to 4 cm. 5. The surface tension at 20 ° C. of the ink 40 to 50 dyn /
The inkjet recording method according to any one of claims 1 to 3 , which is in a range of 1 cm to 4 cm.