JPS6155548B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an inkjet recording method, particularly,
The present invention relates to an inkjet recording method for recording on woven fabric using pigment-based ink. Among the various recording methods currently known, this non-impact recording method generates almost no noise during recording, is capable of high-speed recording, and can record on plain paper without requiring any special fixing process. The so-called inkjet recording method that can be used is recognized as an extremely useful recording method. Regarding inkjet recording methods, various methods have been proposed so far, some have been improved and commercialized, and efforts are still being made to put them into practical use. . This inkjet recording method is a method in which small droplets of a recording liquid called ink are ejected using various principles of operation, and the droplets are attached to a recording material such as paper to perform recording. In this inkjet recording method, several droplet formation methods are employed. An example is shown in FIG. That is, the apparatus shown in FIG. 1 applies a recording signal to a recording head section having a piezo vibrator, and performs recording by generating droplets of recording liquid in response to the signal.
In FIG. 1, reference numeral 1 denotes a recording head, which has a piezo vibrator 2a, a diaphragm 2b, an inlet 3 for recording liquid, a liquid chamber 4 in the head, and an ejection port (ejection orifice) 5. A recording liquid 7 stored in a storage tank 6 is introduced into the liquid chamber 4 through a supply pipe 8 . Incidentally, an intermediate treatment means 9 such as a pump or a filter may be provided in the middle of the supply pipe 8 depending on the case. And in the piezo vibrator 2a,
A signal converted from the recording signal S into a pulse by the signal processing means (for example, a pulse converter) 10 is applied, and a pressure change occurs in the recording liquid in the liquid chamber 4 in accordance with the signal. As a result, the recording liquid 7 is ejected from the ejection orifice 5 as droplets 11, and the recording material 12 is
Recording is done on the surface of the In addition to the above devices, various types of devices are known. For example, as shown in FIG.
As a modification of the figure, there is a device in which the liquid chamber 4 is shaped like a nozzle and a cylindrical piezoelectric vibrator is installed around the outer periphery (the mechanism of droplet generation in this device is essentially the same as in FIG. 1). (same as the equipment shown). Also, a device that continuously generates charged droplets and uses a portion of the droplets for recording. Alternatively, there is also known an apparatus that applies thermal energy corresponding to a recording signal to the recording liquid in the chamber of a recording head and generates droplets using the energy. An example thereof is shown in Fig. 3-a, Fig. 3-b, and Fig. 4. The head 13 is made of glass, ceramic, plastic plate, etc. having grooves 14 through which ink passes, and a heat-generating head 15 used for thermal recording (a thin film head is shown in the figure, but is not limited to this). Obtained by gluing. The heat generating head 15 has a protective film 1 formed of silicon oxide or the like.
6. Aluminum electrodes 17-1, 17-2, heating resistor layer 18 made of nichrome, etc., heat storage layer 1
9. It is made of a substrate 20 having good heat dissipation properties such as alumina. The ink 21 has reached the discharge orifice 22 and forms a meniscus 23 due to the pressure P. Now, when an electric signal is applied to the electrodes 17-1 and 17-2, the area indicated by n of the heat generating head 15 suddenly generates heat, bubbles are generated in the ink 21 in contact with this area, and the pressure causes the meniscus 23 to protrudes, and the ink 21 is ejected from the orifice 22 into a recording droplet 2.
4 and flies toward the recording material 25. Fourth
The figure shows an external view of a multi-head in which a large number of heads shown in Figure 3-a are arranged. The multi-head is made by gluing together a glass plate 27 having multi-grooves 26 and a heating head 28 similar to that described in FIG. 3-a. Note that FIG. 3-a is a cross-sectional view of the head 13 along the ink flow path, and FIG. 3-b is a cross-sectional view taken along line A--B in FIG. 3-a. The ink used in the inkjet recording method described above is basically composed of a dye and its solvent, and the physical properties of the ink largely depend on the inherent properties of the dye. Therefore, conventionally,
When inkjet recording is performed using ink containing mainly water-soluble dyes, the resulting ink images are affected by the physical properties of the water-soluble dyes, resulting in poor water resistance and light resistance. There were flaws. Furthermore, the storage stability of ink itself containing such water-soluble dyes is not particularly high. Therefore, recently, attempts have been made to apply pigment-based inks to inkjet recording systems instead of such dye-based inks. This pigment-based ink has the advantage that the light fastness and water resistance of the resulting ink image are extremely good compared to images made using the dye-based ink. However, since the pigment is insoluble in the ink medium, a sophisticated technique is required to finely disperse it in the ink, and it is extremely difficult to improve its dispersion stability. Nevertheless, in the inkjet recording method, ejection conditions (piezoelectric element drive voltage, drive frequency,
Liquid physical properties (viscosity, surface tension,
electrical conductivity, etc.). Stable for long-term storage and should not cause clogging of the inkjet device. The dots should be placed on the recording material (paper, cloth, film, etc.) quickly and reliably, and the periphery of the dots should be smooth and have little bleeding. The color tone of the formed ink image is clear and has a high degree of clarity. The formed ink image has excellent water resistance and light resistance. Do not damage materials surrounding the ink (container, connecting tube, sealing material, etc.). It is desired to have various properties such as low odor and toxicity, and excellent safety such as flammability. Furthermore, when the recording material is a woven fabric, wash resistance (including dry cleaning) is also required. However, it is quite difficult to simultaneously satisfy the above characteristics. The prior art described above is
In this respect, it was very unsatisfactory. The present invention eliminates the drawbacks of the prior art described above, satisfies ejection stability, long-term storage stability, fixing performance, image density, sharpness, water resistance, light resistance, and washing resistance at the same time, and furthermore, eliminates odor. The object of the present invention is to provide an inkjet recording method using a highly practical ink that is non-toxic, has excellent safety such as flammability, and is highly practical. Accordingly, in the inkjet recording method of the present invention, a small drop of ink comprising fine pigment particles dispersed in an aqueous dispersion medium containing a polymer having both a hydrophilic structure part and a hydrophobic structure part is applied. The method is characterized in that the ink droplets are used to record on a woven fabric. Here, the pigment-based ink used in the present invention will be explained in detail. Pigment particles do not dissolve in solvents such as water, so even if they are simply mixed and dispersed in an ink solvent, they will immediately coagulate or settle and separate from the solvent, making it difficult to compose a practical ink. Can not. Therefore, when preparing such pigment-based ink,
A good dispersion medium for pigment particles is required. Therefore, in the present invention, the first dispersion medium is
A polymer (dispersant) having both a hydrophilic structural part and a hydrophobic structural part is used as a component, and an aqueous liquid is used as the second component. This dispersion medium can disperse the pigment particles very stably in a viscosity range of about 1 to 20 cps. The polymer used as the first component of the dispersion medium is a polymer of monomers mainly having addition-polymerizable vinyl groups, and has hydrophilic properties such as carboxylic acid groups, sulfonic acid groups, and sulfuric acid ester groups. The structural moiety is a predetermined amount of acrylic acid, methacrylic acid, crotonic acid, itaconic acid, itaconic acid monoester, maleic acid, maleic acid monoester, fumaric acid, fumaric acid monoester, vinyl sulfonic acid, sulfoethyl methacrylate, sulfopropyl Alpha and beta-unsaturated monomers such as methacrylates and sulfonated vinylnaphthalenes are used to incorporate them into the polymer structure. On the other hand, monomer units for introducing hydrophobic structural moieties include styrene, styrene derivatives, vinylnaphthalene, vinylnaphthalene derivatives, and α/β.
- _C8 to _C18 aliphatic alcohol esters of ethylenically unsaturated carboxylic acids are most preferred. In addition to the above monomer units, for example, acrylonitrile, vinylidene chloride, α・
β-ethylenically unsaturated carboxylic acid ester, vinyl acetate, vinyl chloride, acrylamide, methacrylamide, hydroxyethyl methacrylate, hydroxypropyl methacrylate, glycidyl methacrylate, N-methylolacrylamide,
N-methylolmethacrylamide, N-butoxymethylacrylamide, etc. can be used. In particular, from the viewpoint of wash resistance, it is desirable that N-methylol acrylamide or N-methylol methacrylamide be copolymerized. By the way, in the present invention, this polymer is
It is necessary to form salts of the polymers for the purpose of solubilization or colloidal dispersion in the component aqueous liquids. As partners for forming salts with the above polymer, in addition to the alkali metals Na and K, mono, di, or tri (methylamine), mono,
Aliphatic amines such as G or tri (methylamine), alcohol amines such as mono, G or tri (ethanolamine), mono, G or tri (propanolamine), methylethanolamine, dimethylethanolamine, etc. , morpholine, N-methylmorpholine, etc. In the above polymer, the ratio of monomer units forming hydrophilic structural parts is particularly important. In other words, when the weight ratio of monomer units forming hydrophilic structural moieties such as carboxyl groups, sulfonic acid groups, or sulfuric acid ester groups exceeds approximately 40% by weight, the adsorption of the polymer to pigment particles decreases. This deteriorates the dispersion stability of pigment particles. On the other hand, when the amount is less than 2% by weight, the solubility of the polymer itself in the aqueous liquid decreases, causing the polymer to coagulate or precipitate in the aqueous liquid together with the pigment particles. Therefore, a more preferable ratio of the hydrophilic structural portion in the above polymer is about 25 to 40% by weight. Furthermore, if the molecular weight of this polymer is too low, it will not contribute to the dispersion stability of the pigment particles, and if the molecular weight is too high, it will tend to increase the viscosity of the ink itself too much (for example, to 20 cps or more). Therefore,
In the present invention, the molecular weight range of this polymer is preferably about 1,000 to 100,000. Such a polymer can be produced according to the following method. For example, by mixing essential monomer components in a predetermined ratio, solution polymerization method, emulsion polymerization method,
A polymer having a desired molecular weight is synthesized by a method such as a suspension polymerization method (using a polymerization regulator if necessary). In addition, polymers containing acid anhydrides, esters, nitrile groups, hydroxyl groups, etc. are prepared first, and these groups are subsequently hydrolyzed, saponified, sulfuric acid esterified, or
There is also a method of subsequently introducing carboxyl groups into the polymer by sulfonation. In addition, the amine salt etc. can be formed at any time, for example, a method of polymerizing using an amine salt of the carboxylic acid monomer, a method of adding an amine etc. after polymerization or after hydrolysis, or a method of adding an amine etc. to the pigment. Any method can be adopted, such as adding an amine or the like after mixing with the particles. In the ink used in the present invention, the amount of the polymer used is approximately 5 to 300 parts by weight, more preferably approximately 10 to 150 parts by weight, per 100 parts by weight of the pigment. If the upper limit of this range is exceeded, there are disadvantages such as a decrease in the color density of the ink and an inability to maintain the viscosity of the ink at an appropriate value. Moreover, when it is below the above-mentioned lower limit, the dispersion stability of the pigment particles becomes poor. The aqueous liquid composition constituting the ink used in the present invention includes water or water and a water-soluble organic solvent. Examples of water-soluble organic solvents include methyl alcohol, ethyl alcohol, n-propyl alcohol, iso-propyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, iso-butyl alcohol, furfuryl alcohol, and tetrahydrofuryl alcohol. Alcohols such as furyl alcohol; ketone or keto alcohols such as acetone, methyl ethyl ketone, diacetone alcohol; alkanolamines such as monoethanolamine, diethanolamine, triethanolamine; amides such as dimethylformamide, dimethylacetamide; tetrahydrofuran, dioxane Ethers such as ethyl acetate, methyl benzoate, ethyl lactate, ethylene carbonate, esters such as propylene carbonate, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, tetraethylene glycol, polyethylene glycol, glycerin, 1, 2, etc. Polyvalent allures such as 6-hexanetriol and thiodiglycol; ethylene glycol monomethyl (or ethyl) ether, diethylene glycol monomethyl (or ethyl) ether, propylene glycol monomethyl (or ethyl) ether, triethylene glycol monomethyl (or ethyl) Lower alkyl mono- or diethers derived from alkylene glycol such as ether, diethylene glycol dimethyl (or ethyl) ether; nitrogen-containing cyclics such as pyrrolidone, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, etc. Compounds, etc. can be mentioned. Among these many solvents, polyhydric alcohols or alkyl ethers of polyhydric alcohols, more preferably polyhydric alcohols such as diethylene glycol, are preferred in order to improve various properties required for ink. Examples include: The content of these components is based on the total weight of the ink.
In terms of weight percentage, generally 10 to 70%, and preferably in order to reduce the temperature sensitivity of physical plants.
It is said to be in the range of 20-50%. Further, the content of water at this time may be in the range of 5 to 90%, more preferably 10 to 70%, and still more preferably 20 to 70%, based on the total weight of the ink. desirable. By the way, all kinds of organic or inorganic pigments including conventionally known pigments can be used as pigments for composing the ink used in the present invention. For example, pigments such as azo, phthalocyanine, quinacridone, anthraquinone, dioxazine, indigo, thioindigo, perinone, perylene, isoindorenone, titanium oxide, cadmium, iron oxide, and carbon black. can be mentioned. These pigments are in the form of fine particles with a particle size of approximately several hundred millimeters to several microns in the ink, and are preferably used in the form of an aqueous paste immediately after production. The preferred concentration of this pigment in the ink is approximately 3 to 30% by weight based on the total weight of the ink, considering its influence on the coloring power and viscosity of the ink. In addition to the above-mentioned essential components, the ink used in the present invention can also contain various conventionally known additives, such as surfactants, salts, synthetic and natural resins, and various dye binders. The ink used in the present invention is composed mainly of the above-mentioned components, and various methods can be employed for its preparation. For example, a method is employed in which the above-mentioned components are blended and mixed and ground using a ball mill, roll mill, speed line mill, homomixer, sand grinder, or the like. The pigment dispersion process is carried out in a state where the pigment is as highly concentrated as possible, and after the dispersion treatment, this is diluted with an aqueous liquid, so that the final viscosity of the ink is approximately 1.
Adjusted to ~220 cps, preferably about 3-10 cps. The ink prepared in this manner does not cause aggregation or sedimentation of pigment particles even when stored for a long period of time in a low viscosity range. This ink has (1) liquid physical properties (viscosity, surface tension, conductivity, etc.) that match a wide range of ink ejection conditions (piezoelectric element drive voltage, drive frequency, ejection orifice shape and material, ejection orifice diameter, etc.); )have. (2) Stable for long-term storage and does not cause clogging of the inkjet device. (3) Fixing to the recording material (woven fabric) is fast and reliable, and the dot periphery is smooth and does not bleed. (4) The color tone of the formed ink image is clear and the density is high. (5) The formed ink image has excellent water resistance and light resistance. (6) Do not damage materials surrounding the ink (container, connecting tube, sealing material, etc.). (7) It has low odor, toxicity, and is non-flammable, making it highly safe. (8) Excellent washability and fastness. It has various characteristics such as. Here, the present invention will be further explained in detail by showing synthesis examples of polymers (dispersants), examples of commercially available products, and practical examples. Dispersant synthesis agent (parts by weight) Example 1 50 ml of water in a four-necked separable flask with a stirrer
1 part, 30 parts of isopropyl alcohol, 0.5 part of sodium dodecylbenzenesulfonate, and 0.5 part of ammonium persulfate are mixed and heated to 60°C. Separately, put a mixed solution of 5 parts of styrene, 6 parts of acrylic acid, 5 parts of butyl acrylate, and 3 parts of N-methylol acrylamide into a separatory funnel and drop it gradually over 60 minutes.After the addition is complete, raise the temperature to 80℃ and add 2 Polymerization was carried out by stirring for hours, and the molecular weight of the obtained polymer was about 50,000. Example 2 Into the same flask as in Example 1, 8 parts of methyl methacrylate, 5 parts of styrene, 2 parts of N-methylolmethacrylamide, 13 parts of itaconic acid, 1 part of benzoyl peroxide, 1 part of lauryl mercaptan, 50 parts of diacetone alcohol, and ethylene. glycol 20
The resulting polymer had a molecular weight of about 30,000. A polymer was obtained from the following raw materials in the same manner as in Example 2. Example 3 Styrene 7 parts Acrylonitrile 5〃 Methacrylic acid 10〃 N-methylolacrylamide 3〃 Hydroxyethyl methacrylate 5〃 Azobisisobutyronitrile 1〃 Ethylene glycol monomethyl ether 19〃 Butanol 50 parts (Molecular weight: approx. 15,000) Example 4 Vinylnaphthalene 8 parts Dimethylamino methacrylate 5 N-methylolmethacrylamide 2 Maleic anhydride 10 Methyl ethyl ketone peroxide 1 Isopropyl alcohol 60 Triethanolamine 14 (Molecular weight: approx. 2,000) Example 5 Styrene 10 parts Maleic anhydride 10〃 Diethanolamine 2〃 Azobisisobutyronitrile 1〃 Ethyl acrylate 5〃 Ethyl carbitol 23〃 Ethylene glycol monomethyl ether 50〃 (Molecular weight: approx. 80,000) Example 6 Styrene 5 parts N-methylolacrylamide 5〃 Itacon Acid monoethyl ester 5 parts methacrylic acid 5〃 2-ethylhexyl methacrylate 10〃 Benzoyl peroxide 1〃 n-propyl alcohol 48〃 Ethylene glycol 20〃 (Molecular weight: approx. 8,000) Example 1 Copper phthalocyanine blue pigment 8 (weight) Polymer obtained in Part Synthesizing Agent 1 15 〃 Dimethylaminoethanol 1 〃 Ethylene Glycol 10 〃 Water 19 〃 After dispersing all the above ingredients in a ball mill for about 18 hours, add 1 part of ethylene glycol until the pigment concentration becomes about 10%. and 26 parts of water were added and dispersion was continued for an additional 30 minutes to obtain a blue pigment dispersion. Furthermore, this dispersion liquid was centrifuged to remove undispersed particles, and a recording liquid was obtained. (Viscosity: approx. 4 cps) Using this recording liquid, an on-demand recording head (discharge orifice diameter 50μ, piezo oscillator drive voltage 60V, frequency
When T ₁ to _{T 5} were examined using a recording device having a frequency of 4KHz), good results were obtained in all cases.
The diameter of the above discharge orifice is approximately 10
It can be set from the range of μ to 200μ. (T ₁ ) Long-term storage stability of the recording liquid: Even after the recording liquid was sealed in a glass container and stored at -30℃ and 60℃ for 6 months, no precipitation of insoluble matter was observed, and the physical properties and color tone of the liquid remained unchanged. There was no change. (T ₂ ) Ejection stability: Continuous ejection was performed for 24 hours in an atmosphere of room temperature, 5° C., and 40° C. Under all conditions, stable high-quality recording was possible from beginning to end. (T ₃ ) Ejection response: Intermittent ejection every 2 seconds and ejection after being left for 2 months were investigated, and in both cases, stable and uniform recording was achieved without clogging at the orifice tip. (T ₄ ) Quality of recorded images: The images recorded on the woven fabrics listed in the table below were high in density and clear. After 6 months of exposure to room light, the density reduction rate was less than 1%, and when immersed in water for 1 minute, there was very little blurring of the image. (T ₅ ) Washing resistance of various woven fabrics: After printing on the following woven fabrics, heat treatment was performed at 150°C for 5 minutes, and washing with detergent in an electric washer and dry cleaning were performed in the usual manner, and all results were good. It showed excellent fastness.

[Table] Example 2 A recording liquid having the following composition was prepared in the same manner as in Example 1, and T ₁ to _{T 5} were examined in the same manner as in Example 1. All of these had excellent recording performance. We also have an on-demand type multi-head (discharge orifice diameter 35μ,
Heat generating resistor resistance value 150Ω, drive voltage 30V, frequency
The same study as in Example 1 was conducted using the recording device shown in FIG. 4 having a frequency of 2KHz) and excellent results were obtained. Recording liquid A Carbon black pigment 10 parts (by weight) Polymer obtained in Synthesis Example 3 15 〃 Dimethylaminoethanol 1 〃 Ethylene glycol 10 〃 Water 19 〃 After dispersing all the above components in a ball mill for about 18 hours, the pigment concentration was 10 %, 1 part of ethylene glycol and 26 parts of water were added, followed by further dispersion for 30 minutes to obtain a black pigment dispersion. Furthermore, this dispersion liquid was centrifuged to remove undispersed particles, and a recording liquid was obtained. (Viscosity: approx. 5 cps) Recording liquid B Copper phthalocyanine blue pigment 15 parts (by weight) Polymer obtained in Synthesis Example 2 15 Morpholine 1 Ethylene glycol 5 Diethylene glycol 5 Water 19 All the above ingredients were mixed in a sand mill for about 18 hours. After dispersion, 25 parts of ethylene glycol, 5 parts of diethylene glycol, and 80 parts of water were added until the pigment concentration was about 10%, and dispersion was continued for another 30 minutes to obtain a blue pigment dispersion. Furthermore, this dispersion liquid was centrifuged to remove undispersed particles, and a recording liquid was obtained. (Viscosity: approx. 6 cps) Recording liquid C Copper phthalocyanine blue pigment 8 parts (by weight) Polymer obtained in Synthesis Example 6 10 N-methylmorpholine 1 ethylene glycol 10 Water 19 parts by weight All the above components were mixed in a ball mill. After dispersing for about 15 hours, 1 part of ethylene glycol and 40 parts of water were added until the pigment concentration was about 10%, and dispersion was continued for another 30 minutes to obtain a blue pigment dispersion. Furthermore, this dispersion liquid was centrifuged to remove undispersed particles, and a recording liquid was obtained. (Viscosity: approx. 4.5 cps) Recording liquid D Quinacridone pigment 8 parts (by weight) Polymer obtained in Synthesis Example 4 15 〃 Dimethylaminoethanol 1 〃 Ethylene glycol 8 〃 Diethylene glycol 2 〃 Water 20 〃 All the above ingredients were mixed in a sand mill to approx. After dispersing for a period of time, 5 parts of ethylene glycol and 30 parts of water were added until the pigment concentration became approximately 7%, and dispersion was further continued for 30 minutes to obtain a red pigment dispersion. Furthermore, this dispersion liquid was centrifuged to remove undispersed particles, which was used as a recording liquid (viscosity: approximately 5 cps).Recording liquid E Carbon black pigment 18 parts (by weight) Polymer obtained in Synthesis Example 5 20 〃 Dimethylaminoethanol 1 〃 Ethylene glycol 10 〃 Water 20 〃 After dispersing all the above ingredients in a ball mill for about 10 hours, 20 parts of ethylene glycol and 40 parts of water were added and dispersed for another 20 minutes until the pigment concentration was about 8%. A black pigment dispersion was obtained. Furthermore, this dispersion liquid was centrifuged to remove undispersed particles, and a recording liquid was obtained. (Viscosity: approx. 8cps)

[Brief explanation of the drawing]

1 and 2 are schematic diagrams of an inkjet recording apparatus, respectively. Figures 3-a and 3-b are a vertical sectional view and a horizontal sectional view of a main part of another recording device. FIG. 4 is an external perspective view of a multi-head head shown in FIGS. 3-a and 3-b. However, in the figure, 1...recording head, 2a...
...Piezo vibrator, 2b...Vibration plate, 3...Inflow port, 4...Liquid chamber, 5...Discharge orifice, 6...
Storage tank, 7... Recording liquid, 8... Supply pipe, 9...
...Intermediate processing means, 10...Signal processing means, 11...
...Droplet, 12, 25... Recording material, S... Recording signal, 14... Liquid chamber, 15... Heat generating head, 16...
... protective layer, 17 ... electrode, 18 ... heating resistor layer, 19 ... heat storage layer, 20 ... substrate, 26 ... groove.

Claims (1)

[Scope of Claims] 1. An ink made by dispersing fine pigment particles in an aqueous dispersion medium containing a polymer having both a hydrophilic structure part and a hydrophobic structure part is made into small droplets, and the ink droplets are used to make a weave. An inkjet recording method characterized by recording on cloth. 2. The inkjet recording method according to claim 1, wherein the ink is ejected from a fine aperture having an opening diameter of 10μ to 200μ and then reduced to small droplets. 3 The molecular weight of the polymer having both a hydrophilic structure part and a hydrophobic structure part in the ink is 1000 to 1000.
100,000. The inkjet recording method according to claim 1, wherein the inkjet recording method is within the range of 100,000. 4. The inkjet recording method according to claim 1, wherein the polymer is a copolymer containing N-methylol-acrylamide or N-methylolmethacrylamide.