JPH0516343A - Ink jet recording method - Google Patents

Abstract

PURPOSE:To obtain an ink jet recording method for forming an image having a high density and no bleeding. CONSTITUTION:In this recording method, pigment-dispersed ink which is solid at an ordinary temperature is jetted onto a recording medium in a hot melt state, and the ink is absorbed into the recording medium so that the pigment is reduced in concentration distribution from the surface into the recording medium. In this manner, even using ink having a relatively small pigment concentration, a high image density can be accomplished, and an image superior in rub resistance, resistance to folding, and light resistance can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet printer, and more particularly to an ink jet recording method in which a solid ink is heated at room temperature and ejected in a molten state.

[0002]

2. Description of the Related Art An ink jet recording method for recording an image by ejecting liquid ink from a nozzle is capable of printing on plain paper, easy to support colorization, and high in printing speed. Due to such advantages, printers based on various ejection principles have been commercially available in recent years. The concrete method of the inkjet method that has been used conventionally is
For example, Journal of Television Society 37 (7) 540 (198)
3) etc. Conventionally, water-based water-based inks and organic solvent-based oil-based inks have been used for inkjet recording. These printers that use ink that is liquid at room temperature have the advantage that the device configuration is simple without the need for a device that heats the ink. However, when the liquid ink is printed on a commonly used paper such as a copy paper, there are disadvantages that a sufficient image density cannot be obtained, the color saturation is lowered, and the image is blurred. In order to cover these drawbacks, the recording is effectively done on special processed paper for inkjet recording.

As a method for eliminating the drawbacks of these liquid inks, USP. 3,653,932, USP. 4,3
90,369, JP-A-55-54368, JP-A-6
No. 1-83268, JP-A No. 62-48774 and the like have proposed an ink jet recording method for heating a solid ink at room temperature to a liquid state and ejecting the ink, and an ink used therefor. By using an ink that is solid at room temperature, a clear single-color or color image can be obtained on a member such as a plastic film, a woven cloth, and a metal surface in addition to plain paper.

However, in the conventional ink jet recording method using a solid ink at room temperature, after the ink is attached to the recording material, it is solidified because it is cooled in an extremely short time of several msecs, as shown in FIG. The ink 1 solidifies while being raised on the surface of the recording material 2 so as to form almost a part of a sphere. The image obtained for this purpose does not feel as natural as the image recorded using a conventional water-based ink, and the image may fall off due to friction or bending, or the image recorded on a binder, etc. There is a problem that an image is transferred to the back side of the piled papers when they are stored in piles.

In order to solve these problems, Japanese Patent Laid-Open No.
No. 3-205241 proposes a method in which an image after printing is heated by a heat roller to remelt the image to improve the fixing property. Further, JP-A-2-51570,
Japanese Unexamined Patent Publication No. 1-2242672 proposes an ink containing a compound having a supercooling property to improve the fixing property. However, in any of these conventionally known techniques, a dye is used as a coloring material of ink. Therefore, when the image after printing is heated, the fixing property of the image is certainly improved, but as shown in FIG. 4, the coloring material is also absorbed in the recording material together with the vehicle, so that the image density is lowered. It is unavoidable that the image gets blurred or blurring occurs in the image. The use of a supercooling agent also has the same drawbacks, and especially when the environmental temperature of printing changes, the time to maintain the liquid state after the ink adheres to the recording material changes and stable image quality can be obtained. could not.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to eliminate the drawbacks of the ink jet recording method and ink which have been used conventionally as described above. Inkjet recording that does not have image bleeding, is a high-quality image with high image density, has extremely excellent light resistance and heat resistance, and has excellent fixability against friction and scratches, and provides an image with a natural touch. It is an object of the present invention to provide a method.

[0007]

According to the present invention, an ink in which a pigment is dispersed and which is solid at room temperature is printed on a recording material in a state of being heated and melted, and the concentration distribution of the pigment goes to the inside of the recording material. The inkjet recording method is characterized in that the recording material is made to absorb the ink so as to become smaller.

[0008] One means of absorbing ink into a recording material so that the concentration of the pigment becomes smaller as it goes inside the recording material is to use an ink composition in which the pigment is dispersed in a supercooling vehicle. Another means is to use a solid ink at room temperature in which a pigment is dispersed, form an image on a recording material, and then heat the image to remelt the ink,
The main purpose is to absorb the vehicle component in the ink into the recording material.

The recording method according to the present invention uses an ink whose color material is pigment particles. Therefore, the state immediately after printing is not different from that obtained by the conventional inkjet recording method as shown in FIG. 1, but when the ink permeates the recording material, the coloring material 3 as shown in FIG. Only the ink remains in the vicinity of the surface of the recording material, and the ink permeating into the recording material has a relatively large amount of the vehicle component 4, and the concentration distribution of the pigment decreases toward the inside.

Next, examples of pigments used in the ink composition usable in the present invention include organic pigments such as azo, phthalocyanine, anthraquinone, quinacridone, dioxazine, indigo and thioindigo. , Perinone type, perylene type, isoindolenone type, aniline black, azomethine azo type, lake pigment, carbon black, and the like, more specifically, benzidine yellow, hansa yellow G, hansa yellow 10G, benzidine orange 2G, watching red, Pigment Scarlet 3B, Brilliant Carmine 6B, Rhodamine B Lake, Alizarin Lake, Alizarin Lake Rose, Permanent Red AG, Phthalocyanine Blue,
Examples include methyl violet lake.

The inorganic pigments include iron oxide, zinc oxide, titanium oxide, lead oxide, lead chromate, zirconium oxide, lead molybdate, calcium carbonate, barium sulfate, aureoline, silicon dioxide, barium yellow, navy blue, cadmium red, Examples include chrome yellow and metal powder.

Of these pigments, the organic pigments are preferable because their specific gravity is small and sedimentation is less likely to occur during dissolution and standing. Particularly preferred from the viewpoint of light resistance, color tone, and dispersion stability are Hansa Yellow G, Hansa Yellow 10G, Alizarin Lake, Alizarin Lake Rose, Rhodamine B Lake, Brilliant Carmine 6B, Phthalocyanine Blue, and carbon black.

In addition to these commonly used pigments, particles obtained by dissolving a dye in styrene, butadiene, ethylene, vinyl acetate, vinyl chloride or the like and emulsion-polymerizing can also be used as the pigment. These particles are preferable in that the particle size can be adjusted to a desired value, and the effect of retaining the pigment at a high concentration near the surface of the recording material is large.

The amount of the pigment that can be used in the present invention is in the range of 0.2 to 20 wt% in the ink composition, and more preferably in the range of 0.5 to 8 wt%. If the density is lower than this, the density of the obtained image will be too low, and if it is higher than this, the color tone of the image will deteriorate and the dispersion stability of the pigment will deteriorate.

Examples of the heat-fusible compound for vehicles used in the ink composition of the present invention include beeswax, carnauba wax, rice wax, wood wax, jojoba oil,
Whale wax, candelilla wax, lanolin, montan
Natural waxes such as wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, petrolactam, polyethylene wax and its derivatives, chlorinated hydrocarbons, palmitic acid, stearic acid, behenic acid, tiglic acid, 2-acetona Organic acids such as futonbehenic acid, 12-hydroxystearic acid, dihydroxystearic acid, dodecanol, tetradecanol, hexadecanol, eicosanol, docosanol, tetracosanol, hexacosanol, octacosanol, 9-dodecen-1-ol, milli Syl alcohol, 9-tetracene-1-ol, 9-hexadecene-
1-ol, 9-eicosen-1-ol, 13-docosen-1-ol, pinene glycol, hinokiol,
Butynediol, nonanediol, isophthalyl alcohol, mesicerine, terephthalyl alcohol, hexanediol, decanediol, dodecanediol, tetradecanediol, hexadecanediol, docosanediol, tetracosanediol, televisionneol, phenylglycerin, eicosanediol. , Octanediol, alcohols such as phenylpropylene glycol,
Benzoylacetone, diacetobenzene, benzophenone, trichosan, heptacosanone, heptatriacontanone, hentriacontanone, stearone, laurone,
Ketones such as dianisole, the above acids and glycerin,
Esters with alcohols such as diethylene glycol, ethylene glycol, oleic acid amide, lauric acid amide, stearic acid amide, ricinoleic acid amide, palmitic acid amide, tetrahydrofuranic acid amide, erucic acid amide, myristic acid amide, 12-hydroxystearic acid Amide, N-stearyl erucic acid amide, N
-Oleyl stearic acid amide, N-oleyl palmitic acid amide, N-oleyl oleic acid amide, N-stearyl stearic acid amide, N-stearyl oleic acid amide, N, N'-ethylenebislauric acid amide,
N, N'-ethylenebisstearic acid amide, N, N '
-Ethylenebisoleic acid amide, N, N'-methylenebisstearic acid amide, N, N'-ethylenebisbehenic acid amide, N, N'-xylylenebisstearic acid amide, N, N'-butylenebisstearic acid Amide,
N, N'-dioleyl adipamide, N, N'-distearyl adipate amide, N, N'-dioleyl sebacate amide, N, N'-distearyl sebacate amide, N, N'-di Stearyl terephthalic acid amide,
Amides such as N, N′-distearylisophthalic acid amide, phenacetin, toluamide, and acetamide, and sulfonamide compounds such as p-toluenesulfonamide, N-ethyl-p-toluenesulfonamide, ethylbenzenesulfonamide, and butylbenzenesulfonamide , Synthetic esters of cholesterol, saccharide esters, bisphenols and the like.

A vehicle having supercooling can be obtained by using a compound having the following supercooling property as a main component of the vehicle. Examples of the compound having supercooling property include bis (2-hydroxylbenzoyloxy) 1,2-ethylene, 1,4-dihydroxy-methoxycarbonylnaphthalene, bis (4'-hydroxybenzyloxy) α,
α'-1,4-xylylene, 4-hydroxyphenylbenzyl thioether, 3,5-dioxapentane-17
-Bis (4'-hydroxyphenyl thioether),
4,4'-dihydroxy-3,3'-di (sec-butyl) diphenylthioether, N-cyclohexyl-3
-Hydroxyaniline, 2- (p-hydroxyphenylthio) ethanol, 6-hydroxyhexyl-4-hydroxybenzoate, benzyl-2,5-hydroxybenzoate, benzyl-3-hydroxybenzoate,
Benzyl-4-hydroxybenzoate, dicyclohexyl phthalate, diphenyl phthalate, 3-phenylpropionic acid, ketoglutaric acid, o-terphenyl, p-tert-butylphenyl salicylate, p-t salicylate.
ert-butylphenyl, salicyl salicylate, p-octylphenyl salicylate, β-naphthyl salicylate, ethylene glycol monostearate, octylmalic acid, decylmalic acid, lauryldiethanol, 2-
Hexadecylindene-1,3-dione, p-α-cumylphenol and the like can be mentioned.

The vehicle may be formulated with these compounds alone or as a mixture with other compounds or as a mixture of the above compounds. By using a supercooling compound and setting the time for the ink to solidify after the ink adheres to the recording material to be sufficient for the vehicle to penetrate the recording material, the printing environment Also, a stable image can be obtained even if the paper type changes. The time required for solidification is preferably 0.2 to 15 seconds.

In addition to the above-mentioned pigments and the essential components of the heat-meltable compound, suitable additives can be added to the ink composition according to the present invention depending on the purpose. For example, as the antioxidant, 2,6-di-tert-butyl-p-cresol, 2-tert-butyl-4-methoxyphenol,
3-tert-butyl-4-methoxyphenol, 2,
6-di-tert-butyl-4-ethylphenol, stearyl-β- (3,5-di-tert-butyl-4-
Hydroxyphenyl) propionate, monophenolic compounds such as 3,4,5-trihydroxybenzoic acid propyl ester, 2,2′-methylene-bis- (4-methyl-6-tert-butylphenol),
2,2'-methylene-bis- (4-ethyl-6-ter
t-butylphenol), 4,4'-thiobis- (3-
Methyl-6-tert-butylphenol), 4,4 '
-Butylidene-bis- (3-methyl-6-tert-butylphenol) and other bisphenol compounds, 11,
1,3-tris- (2-methyl-4-hydroxy-5-
tert-butylphenyl) butane, tetrakis- {methylene-3- (3 ′, 5′-di-tert-butyl-
4'-hydroxyphenyl) propionate} methane,
Bis- {3,3'-bis- (4'-hydroxy-3'-
Butylphenyl) -butyric acid} glycol ester, a high molecular weight phenolic compound such as DL-α-tocopherol, dilaurylthiopropionate,
Sulfur compounds such as dimyristyl thiodipropionate, triphenyl phosphite, diphenyl isodecyl phosphite, 4,4′-butylidene-bis (3-
Phosphorus compounds such as methyl-6-tert-butylphenyl-di-tridecyl) phosphite, tris (nonylphenyl) phosphite and tris (dinonylphenyl) phosphite can be added.

In addition to these components, additives such as surfactants, ultraviolet absorbers, heat stabilizers and preservatives can be added if necessary.

After the image is formed on the recording material, the image is heated to melt the ink again. As a means for heating the image on the recording material after printing, a method of heating the recording material with a heating roller or a heating plate, light is used. A method of irradiating to absorb the image or recording material and converting it into heat, a method of applying hot air to the image, a method of putting the recording material on which the image is recorded in a heated chamber, ink irradiating with microwave or Examples thereof include a method of activating the movement of molecules contained in the recording material.

[0021]

【Example】

Example 1 For the ink, a mixture having the following formulation was placed in a porcelain ball mill pot, and a dispersion operation was carried out for 48 hours while being heated to about 100 ° C. on a frame in which the pot was rotated by a heat roller. After adding 3 parts by weight of decylmalic acid to 1 part by weight of the obtained pigment dispersion, the mixture was heated to about 100 ° C., dissolved and stirred, and filtered under heat using a filter having a pore size of 5 μm to obtain an ink composition. It was

Phthalocyanine blue 16.0 wt% Decylmalic acid 73.5 wt% 2-Ethylhexyl methacrylate / styrene copolymer 10.0 wt% Cobalt naphthenate 0.5 wt% The ink composition obtained above is driven by piezo. Printing was performed by filling in an ink jet printer. The heater in the vicinity of the head was energized so that the ink in the head was heated to 110 ° C. Nozzle diameter is about 50 μm
Piezo element with a frequency of 16 KHz, 30
It was driven with a voltage of v.

Printing on polyester film,
The time taken for the ink to solidify was about 11 seconds.

As the recording material, commercially available copy paper, high-quality paper, recycled paper, and bond paper were used for printing. The image obtained on any of the papers had a high density of 1.2 to 1.6 and had no bleeding.

The fixability of the obtained image was measured by applying a weight of 750 g to a commercially available sand eraser, rubbing it 10 times, and measuring the rate of decrease in density before and after rubbing with a Macbeth densitometer. At the same time, it was observed whether or not the background stain was generated by rubbing. As a result, the reduction rate of the concentration was 0 to 3%, which was practically no problem. Moreover, the soiling of the background was not observed. In order to check the image loss due to bending of the solid print part,
After folding the printed recording paper, trace it by hand 1
The peeled state of the image was observed by repeating 0 times. The judgment was performed as follows.

[0026] Almost no peeling observed ◎ Those that do not peel off to a white background ○ Paper exposed width of 0.2 mm or less △ Exposed width of paper exceeds 0.2 mm × The printed result was ◯ to ⊚.

Further, the image obtained here has a natural feeling (the height of dots is 5 μm or less) with little swelling.
Met.

In addition, the light resistance of the obtained image is faded.
When examined by irradiation with a meter for 6 hours, the residual ratio of image density was as high as 98.8 to 100%.

Comparative Example 1 Dye C.I. was used in place of the pigment phthalocyanine blue. I. An ink having the same formulation as in Example 1 except that Solvent Blue 73 was used was stirred and filtered while being heated at about 110 ° C. to obtain a test ink composition. Using this ink, printing and testing were performed in the same manner as in Example 1. The obtained image had the same frictional fixability as that of Example 1, but the density was 0.8 to 1.
It was as low as 2 and the image was blurred. In addition, the residual ratio of the image density after irradiation with a fade meter for 6 hours is 94.3-9.
It was 7.5%.

Comparative Example 2 C. I. Solvent Blue 73 1.5 wt% Stearone 64.0 wt% Monostearin 32.0 wt% Carnauba wax 2.5 wt% Stir while stirring the mixture of the above formulation at about 100 ° C.
It was filtered to obtain a test ink composition. Using this ink, printing and testing were performed in the same manner as in Example 1. The density and sharpness of the image obtained using this ink were the same as in Example 1, but there was a 6-9% decrease in density in the friction test, and the bending test resulted in Δ to ×. Example 2 Rhodamine B lake 15.0 wt% Paraffin wax (melting point 69 ° C.) 61.0 wt% Carnauba wax 10.0 wt% Acetylcellulose 4.5 wt% Polyester resin 7.5 wt% Decyldimethylbenzylammonium bromide 1.3 wt% Above The mixture of the formulations was subjected to the dispersion operation for 48 hours in the same manner as in Example 1. To 1 part by weight of the obtained pigment dispersion,
After adding 3 parts by weight of paraffin wax, about 100 ℃
The mixture was heated to 1, dissolved and stirred, and filtered while hot with a filter having a pore size of 5 μm to obtain an ink composition.

Using this ink, printing and testing were carried out in the same manner as in Example 1. The obtained image was placed in a thermostat heated to 90 ° C. for 13 seconds to remelt the ink forming the image.

The image density was 1.1 to 1.5, which was sufficiently high, and there was no image bleeding. The rate of decrease in density before and after rubbing was 0 to 2%. No dirt on the background due to friction was observed. The result of bending resistance was ○ to ◎.

Comparative Example 3 When the abrasion resistance of the image obtained in Example 2 before reheating was examined, the reduction rate of the image density was 6-.
16%, which was larger than that in Example 2. The result of bending resistance was Δ to ×.

[0034]

As is apparent from the above description, according to the present invention, (1) the ink jet recording method according to claim 1,
An ink containing a dispersed pigment is used so that the recording material absorbs the ink so that the concentration distribution of the pigment becomes smaller as it goes inside the recording material. It is possible to obtain an image in which the density can be achieved, and there is no bleeding and which is excellent in abrasion resistance, bending resistance, and light resistance.

(2) In the ink jet ink composition according to the second aspect, the vehicle has supercooling properties and uses a pigment as a coloring material. Therefore, after printing, especially the image is reheated. Even if you do not do this, the vehicle penetrates inside the recording material while leaving the pigment near the surface of the recording material, so you can achieve high image density even with ink with a relatively low pigment concentration, and there is no bleeding. , Abrasion resistance,
Images with excellent bending resistance and light resistance can be obtained.

(3) In the ink jet recording method according to the third aspect, an ink in which a pigment is dispersed is used,
After the image is formed, the image is heated and remelted.Therefore, even if a special compound having a supercooling property is not used as a vehicle, the ink is coated so that the concentration distribution of the pigment becomes smaller as it goes inside the recording material. Since it is absorbed by the recording material, a high image density can be achieved even with an ink having a relatively low pigment concentration, and an image free from bleeding and excellent in abrasion resistance, bending resistance, and light resistance can be obtained.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a state immediately after printing in the present invention.

FIG. 2 is an explanatory diagram showing a state after the ink according to the present invention has penetrated into a recording material.

FIG. 3 is an explanatory diagram of a state immediately after printing when a conventional solid ink at room temperature is used.

FIG. 4 is an explanatory diagram of a state after the ink permeates the recording material in the conventional method.

[Explanation of symbols]

1 ink 2 Recording material 3 pigments 4 vehicle components

Claims (3)

[Claims] 1. An ink, in which a pigment is dispersed and which is solid at room temperature, is printed on a recording material in a state of being heated and melted, and the ink is so designed that the concentration distribution of the pigment becomes smaller as it goes inside the recording material. An ink jet recording method, characterized in that it is absorbed by a recording material. 2. The ink jet recording method according to claim 1, wherein an ink in which a pigment is dispersed in a vehicle having a supercooling property is used as the ink which is solid at room temperature. 3. An ink formed by dispersing a pigment in a heat-fusible vehicle is used as the ink that is solid at room temperature, and the image formed on the recording material is heated so that the ink is absorbed by the recording material. Inkjet recording method.