JPH05247390A - Hot-melt ink composition and method for recording using the same - Google Patents

Abstract

PURPOSE:To provide the subject ink composition containing a compound solid at ordinary temperature and having a melting point and a boiling point and a coloring agent comprising a sublimable dyestuff, in part or in whole not causing change in the quality of the dyed picture by the difference in the kind of paper and useful for ink jet recording, etc. CONSTITUTION:At least one of compounds (e.g. methyl sulfone) solid at ordinary temperature and having a melting point and a boiling point is compounded with a coloring agent comprising a sublimable dyestuff in part or in whole (e.g. disperse yellow) having a sublimation starting temperature of >=100 deg.C to provide the objective hot-melt ink composition not causing large change in the quality of the printed picture by the difference in the kind of paper and useful for a hot-melt ink recording style. The ink composition is kept in the state melted with a heater, fed into the head of a thermal jet recording device through an ink-feeding pipe 6, and subsequently subjected to the selective application of thermal energy with a heat-generating element 2. The melted ink is flown through an ink-extruding nozzle 1 as small drops to form a picture on recording paper.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot melt ink composition and a recording method using the hot melt ink composition. More specifically, the hot melt ink composition is suitable for use in printing of OA equipment and is particularly suitable for a thermal ink jet recording system. The present invention relates to a recording method using the ink.

[0002]

2. Description of the Related Art In recent years, printers such as an ink jet recording system and a thermal transfer recording system have been widely adopted as a print output device such as an office automation equipment. Among them, the inkjet recording method mainly includes a thermal inkjet (bubble jet) recording method which is a recording method by heating ink by a thermal element, and a hot melt ink recording method in which a hot melt ink is melted and ejected by a head using PZT. There is. However, since the thermal ink jet recording method uses water-based ink, the image quality greatly changes depending on the paper type. On the other hand, the hot-melt ink recording method using PZT has a problem that it is difficult to increase the density and size of the head.

Therefore, several hot melt inks suitable for the thermal head ink jet system have been proposed. For example, JP-A-55-54368 and JP-A-1
Those disclosed in gazettes such as -263171 and JP-A-3-37278 can be cited. However, as far as the descriptions in these documents are concerned, the thermal inkjet method is 300
Since the ejection control is performed by heating the ink at a temperature of not less than 0 ° C., it is difficult to secure the reliability even when using the water-based ink. Furthermore, even when a hot melt ink is used, a high quality recorded image cannot be obtained due to the decomposition of the dye in the ink, and there is a great risk of significantly impairing the reliability.

[0004]

SUMMARY OF THE INVENTION A first object of the present invention is to improve reliability in a thermal ink jet recording system using a hot melt ink which enables a high speed and high resolution ink jet recording system compatible with plain paper color. It is intended to provide a recording material (hot melt ink composition). A second object of the present invention is to provide a hot-melt ink for thermal ink jet recording, which gives a stable image even when continuously printing for a long time and has a high image storability. A third object of the present invention is to provide a recording method for performing suitable recording using a hot melt ink for thermal ink jet recording. A fourth object of the present invention is to provide a recording method suitable for ensuring reliability by using a hot melt ink for thermal inkjet recording.

[0005]

The present invention provides a hot melt ink composition for use in a thermal ink jet recording system, which comprises a colorant and at least one compound that is solid at room temperature and has a melting point and a boiling point. Part or all of the agent is a sublimable dye.

One of the recording methods of the present invention comprises at least one compound that is solid at room temperature and has a melting point and a boiling point, and a sublimable dye in which a part or all of the colorant has a sublimation initiation temperature of 100 ° C. or higher. A hot melt ink composition containing the composition is used, and heat energy is selectively applied to the composition in a molten state, and the molten ink is made to drop and fly to form an image on a recording paper.

Another of the recording methods of the present invention is that at least one of the vehicle main components consisting of a compound which is solid at room temperature and has a melting point and a boiling point and a part or all of the colorant have a sublimation initiation temperature of 100 ° C. or higher. And a sublimation dye having a sublimation start temperature higher than the melting point of the vehicle main component by 10 ° C. or more is used, and heat energy is selectively applied in a molten state to drop the melted ink. The feature is that an image is formed on the recording paper by flying.

The "sublimation start temperature" referred to in this specification
Means the temperature at which the sublimable dye undergoes a weight change due to vaporization when the endothermic heat generation and the thermogravimetric change are measured by a differential thermogravimetric measurement device.

The present inventors have conducted a lot of studies on the thermal ink jet recording system, but hot melt inks using a sublimable dye as part or all of the colorant (preferably all of the colorant). It was confirmed that good results can be obtained by using the ink, and a more desirable image can be obtained by using such an ink and making an effort for recording. The present invention is made by these.

The present invention will be described in more detail below with reference to the accompanying drawings. FIG. 1 shows an outline of a thermal inkjet recording head unit. As mentioned above, a hot-melt ink composition (hereinafter sometimes simply referred to as “ink” or “in liquid”) has a melting point and a boiling point and has a sublimation initiation temperature of 10 in a vehicle that is solid at room temperature.
A sublimation dye of 0 ° C. or higher is dispersed as a colorant. This is introduced into the ink liquid chamber 5 through the ink supply pipe 6. On the other hand, the heat from the heater 7 is used to bring the ink in the ink liquid chamber 5 from the heat storage layer 8 into a molten state according to its composition.

Heat energy is selectively applied to the melted ink liquid by the heating element 2 to cause film boiling, and the hot melt ink is stably discharged.
Then, the image is formed on a recording paper (not shown) such as plain paper by flying in a droplet form from the outside.

In a thermal ink jet recording system using a water-based ink, reliability can be secured by dissolving a dye decomposition product in water. However, in the case of a hot-melt type ink, the dye decomposition product is generally redissolved in a dispersion medium. It is difficult to do so, or the reliability is extremely poor. On the other hand, in the present invention, by using a sublimable dye as a colorant, ejection failure due to thermal decomposition of the dye can be improved. Further, by setting the sublimation start temperature of the sublimable dye to 100 ° C. or higher, It has been found that a thermal inkjet recording ink can be applied which has excellent ejection stability even after continuous printing for a period of time, and which does not cause re-sublimation of dye and has excellent storage stability of recorded images.

In a hot melt ink containing a vehicle-based solid compound having a melting point and a boiling point as a vehicle main component and a sublimable dye as a colorant, the sublimation starting temperature is 10 ° C. or higher than the melting point of the vehicle main component having a boiling point. A stable image can be recorded by using a high ink and heating the ink in a molten state at a temperature not higher than the sublimation start temperature to cause film boiling to cause the ink to drop and fly. On the other hand, when the sublimation start temperature and the melting point of the vehicle main component are out of the range, it is recognized that only the dye sublimes, and thus stable image quality cannot be obtained. Furthermore, more preferably 30
It is preferable to make the sublimation start temperature higher than the vehicle melting point by not less than 0 ° C.

As the sublimable dye in the hot melt ink composition according to the present invention, any dye that can be sublimated by heat and has a sublimation initiation temperature of 100 to 250 ° C. can be used. Among the dispersible dyes and the meltable dyes described in (1), it is preferable to select one having particularly excellent solubility. Specifically, C.I. I. Disperse Yellow 1,3,7,8,9,2
3, 42, 54, 60, 82 C.I. I. Disperse Red 1,9,11,13,1
5, 17, 53, 58, 60 C.I. I. Disperse Blue 1, 3, 5, 14, 19,
24, 26, 60, 71, 99, 108 C.I. I. Solvent Yellow 18, 30, 77, 116 C.I. I. Solvent Red 19, 23, 25 C.I. I. Solvent Blue 11,35,36,63,8
3,105 and the like. These may be used alone or in combination of two or more. And, they are contained in the ink composition at 0.1 to 20% by weight, preferably 0.5 to 5%.
It is contained by weight%. Since these commercially available dyes may not necessarily have high purity, it is preferable to use them after purifying them so that the sublimation initiation temperature is as constant as possible.

The compound having a melting point and a boiling point (used as a vehicle component) which is a solid at room temperature in the hot melt ink composition according to the present invention has a melting point of 60 ° C.
Thus, the boiling point is preferably 150 ° C or higher and 300 ° C or lower. Specific examples thereof include lower alkyl amides such as acetamide, propionamide, n-butylamide, lactamide and derivatives thereof, and urea derivatives such as 1,3-dimethylurea and ethylurea. Lower alkyl sulfones such as methyl sulfone and ethyl sulfone, carboxylic acids such as phenyl sulfone and benzoic acid, imidazole derivatives such as imidazole, 2-ethyl-imidazole and 1,2,4-triazole, pyrazole and 3,5-dimethylpyrazole. Pyrazole derivatives such as biphenyl, p-tert-butylphenol, phenol derivatives such as 2,6-tert-butyl-p-cresol, piperazine, o- or p-toluenesulfonamide, alkylbenzenesulfonamide such as ethylbenzenesulfonamide, methane Examples thereof include lower alkyl sulfonamide derivatives such as sulfonamide, and imides such as succinimide and maleimide. Of these, particularly preferred are propionamide, methyl sulfone, ethyl sulfone, lactamide, imidazole and the like. The content of these compounds may be any content as long as ejection energy can be obtained, but the content is preferably 10 to 90% by weight, more preferably 30 to 80% by weight. Can also be used.

The hot melt ink composition according to the present invention may further contain a tackifying component and a binder resin for the purpose of improving the fixability on recording paper. For example, abietic acid esters (particularly hydrogenated to improve heat resistance), low-melting polyamide resin containing nylon 12, and temiramides such as Unilett X37-525-235 available from Union Camp, maleic acid resin, styrene. -Butadiene copolymer, vinyltoluene-butadiene copolymer, styrene-acrylate resin,
Vinyltoluene acrylate resin, alkyd resin, ethylene-vinyl acetate resin, stearyl stearamide, fatty acid amide derivatives such as ethylenebisstearylamide,
Microcrystalline wax, waxes such as carnauba wax, polyhydric alcohol fatty acid esters such as propylene glycol monohydroxystearate, glycerin monohydroxystearate, aliphatic ketones such as stearone, decyl sulfone, sulfones such as phenyl sulfone, Long-chain alcohols such as octadecyl alcohol and stearyl alcohol, aliphatic phosphates such as stearyl assid phosphate, cholesterol,
Examples thereof include cholesterol derivatives such as cholesterol stearyl ester. Further, a plasticizer such as phthalates, polyesters and polyhydric alcohols can be added together with these binders.

Various other additives may be added to the hot melt ink composition according to the present invention depending on the purpose. For example, an ultraviolet absorber, a supercooling agent, an antioxidant, a surfactant, etc. may be mentioned.

[0018]

EXAMPLES Next, the present invention will be described more specifically with reference to Examples and Comparative Examples. The percentages here are by weight.

Example 1 The following composition was heated and melted at 100 to 120 ° C., stirred for 1 hour, and filtered through a Teflon filter having a diameter of about 1 μm to obtain an ink 1. C. I. Disperse Yellow 7 (sublimed above 120 ° C) 2% Methyl sulfone (melting point 109 ° C) 70% Phenylsulfone 17% 2,6-tert-Butyl-p-cresol 1% Water-added abietic acid glycerin ester 10%

Example 2 Ink 2 was prepared in the same manner as in Example 1 except that the following composition was used.
Was prepared. C. I. Disperse Red 9 (sublimated above 120 ° C) 2% Imidazole (melting point 90 ° C) 50% Octadecyl alcohol 20% Cholesterol stearyl ester 20% 2,6-tert-Butyl-P-cresol 8%

Example 3 Ink 3 was prepared in the same manner as in Example 1 except that the following composition was used. C. I. Solvent Blue 35 (sublimates above 110 ° C) 3% Lactamide (melting point 73-76 ° C) 70% Water-added abietic acid 10% Stearyl acid phosphate 17%

Example 4 Ink 4 was prepared in the same manner as in Example 1 except that the following composition was used. C. I. Solventlet 19 (sublimates above 120 ° C) 2% Propionamide (melting point 80 ° C) 80% Polyamide resin consisting of nylon 6,12 (melting temperature 90 ° C) 5% Ethylbenzenesulfonamide 12% Triphenylphosphite 1%

Comparative Example 1 C.I. I. Non-sublimable C.I. instead of Disperse Yellow 7 I. Ink 5 was prepared in the same manner except that Solvent Yellow 120 was used.

Comparative Example 2 C.I. I. Ink 6 was prepared in the same manner except that non-sublimable Solvent Red 49 was used instead of Disperse Red 9.

Comparative Example 3 C.I. I. Ink 7 was prepared in the same manner except that the solvent blue 35 was changed to the non-sublimable solvent blue 70.

Using these seven kinds of inks, a printing test was conducted in a recording apparatus having a thermal ink jet recording head shown in FIG. At this time, Table 1 shows the results obtained by performing the ejection for each ink continuously by ejecting for 1 hour.

[Table 1] Note) Comparative Example 4 is a case where the same ink as in Example 4 was used and only the heating temperature was changed.

[0027]

According to the first aspect of the present invention, since the ascending dye can be used as the colorant, the efficiency of the thermal element is not lowered and the jetting direction is not changed due to the decomposition of the dye. You can do it. According to the second aspect of the present invention, by setting the sublimation start temperature of the sublimable dye to 100 ° C. or higher, image deterioration due to resublimation of the printed image does not occur, and stable continuous printing can be performed. According to the invention of claim 3, high-speed and high-resolution color recording can be stably performed. According to the invention of claim 4, the sublimation start temperature of the sublimable dye is set to 10 ° C. or more higher than the melting point of the vehicle main component having a boiling point, the ink is melted at the sublimation start temperature or less, and heat energy is selectively applied. Highly reliable image recording can be performed by performing the recording.

[Brief description of drawings]

FIG. 1 is a diagram showing an outline of a head portion of a thermal jet recording apparatus used in a method of the present invention. 1 Ink Ejection Nozzle 2 Heating Element 3 Base 4 Nozzle Plate 5 Ink Liquid Chamber 6 Ink Supply Pipe 7 Heater 8 Heat Storage Layer

Claims (4)

[Claims] 1. A hot melt ink containing a colorant and at least one compound that is solid at room temperature and has a melting point and a boiling point, characterized in that part or all of the colorant is a sublimable dye. Hot melt ink composition. 2. The sublimation dye has a sublimation initiation temperature of 100.
The hot melt ink composition according to claim 1, which has a temperature of not less than ° C. 3. A hot melt ink composition comprising at least one compound that is solid at room temperature and has a melting point and a boiling point and a sublimation dye in which a part or all of a colorant has a sublimation initiation temperature of 100 ° C. or higher. A recording method, wherein heat energy is selectively applied in a molten state, and the molten ink is made to drop and fly to form an image on a recording paper. 4. At least one of the vehicle main components consisting of a compound that is solid at room temperature and has a melting point and a boiling point and a part or all of the colorant have a sublimation start temperature of 100 ° C. or higher, and the sublimation start temperature is the vehicle main component. A hot-melt ink containing a sublimable dye having a temperature higher than the melting point of a component by 10 ° C. or more is used, and thermal energy is selectively applied to the hot-melt ink in a molten state, and the melted ink is made to drop and fly to form an image on a recording paper. Recording method characterized by.