JPS629626B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an inkjet recording method in which ink droplets are formed using thermal energy and are used to perform recording. Non-impact recording methods have recently attracted attention because the noise generated during recording is so small that it can be ignored. Among these non-impact recording methods, the so-called inkjet recording method (liquid jet recording method), which enables high-speed recording and can record on plain paper without the need for special processing, is an extremely useful recording method. Until now, various methods have been proposed and devices have been devised to implement them, some have been improved and commercialized, and efforts are still being made to put them into practical use. There are some. Among them, for example, the liquid jet recording method described in Japanese Patent Application Laid-Open No. 54-51837 and German Opening Publication (DOLS) No. 2843064 applies thermal energy, which is the energy for forming ink droplets, to the ink. It has a different feature from other liquid jet recording methods in that it obtains the motive force for ejecting droplets. That is, in the ink jet method disclosed in the above-mentioned publication, the ink undergoes a state change accompanied by a sharp increase in volume under the action of thermal energy, and the acting force based on this state change causes the recording head portion to Ink droplets are ejected from the orifice at the tip, fly, and adhere to an arbitrary recording material such as paper to perform recording. When using such an inkjet method to record high-resolution, high-quality images at higher speeds and over longer periods of time, it is especially important that the ink used has performance that inks used in other methods do not have. is required. In other words, in the inkjet recording method using thermal energy as described above, it is necessary that the ink used has good thermal responsiveness and also has excellent stability in ink droplet formation. In view of the above points, the present invention has been made to improve the thermal performance of the applied ink and to provide an inkjet recording method suitable for stably recording high-resolution, high-quality images at high speed over a long period of time. The main purpose is to provide The present invention, which has achieved such an object, is an ink jet recording method in which thermal energy is applied to ink to form ink droplets, and recording is performed using these ink droplets, in which the ink dissolves or disperses the recording agent and the ink droplets. It is composed mainly of a liquid medium, and in 1 ml, converted to the conditions of 0°C and 760 mmHg.
It is characterized by having dissolved gas in an amount of 0.01ml or more. In other words, in the ink jet recording method of the present invention, the amount of gas dissolved in the ink is calculated based on the conditions of 0°C and 760 mmHg per ml of ink.
It needs to be 0.01ml or more. Even more,
In order to obtain a noticeable effect, use the same converted value.
It is considered to be 0.012ml or more. Further, the upper limit of the amount of dissolved gas is the saturated amount at the usage environment temperature. As mentioned above, in the present invention, by actively dissolving gas in the applied ink, the amount of thermal energy required for recording is significantly reduced, and the thermal responsiveness and ink droplet formation are improved. The stability is extremely good, and even when recording is performed continuously for a long time, the supply speed in the nozzle can sufficiently follow the recording speed, and there is also a decrease in thermal response and stability in ink droplet formation. Hateful. Therefore, according to the present invention, recording can be performed with low energy consumption, stable recording can be performed at all times, and the recorded image has high clarity, sufficient density, and high quality without satellite dots. You can get something. In the present invention, the gas dissolved in the ink has the function of promoting the ejection of ink from the orifice of the nozzle during recording, as will be demonstrated in later examples. Compared to ink that has been subjected to degassing treatment, it is possible to perform recording with lower energy consumption, and the thermal response during high-speed recording is also significantly improved, which is a remarkable effect. In the present invention, the gas dissolved in the ink is one that does not cause any adverse effects such as forming precipitates in the treated ink or causing undesirable chemical reactions with other components constituting the ink. , and most gases are suitably employed as long as they are not harmful to the human body. Specifically, such gases include, for example, hydrogen, nitrogen, oxygen, air, helium, neon, argon, krypton, xenon, methane, ethane,
Examples include ethylene and acetylene. Other gases may be appropriately mixed and used as required. From an economic standpoint, gases such as nitrogen, carbon dioxide, oxygen, and air are preferably employed in the present invention. In the present invention, in the ink preparation process,
The gas can be dissolved in the ink by blowing gas into the ink, or by blowing gas into the cooled liquid. Furthermore, as the liquid medium for composing the ink, many commercially available so-called solvents, which are used to dissolve or disperse recording agents made of dyes and pigments, can be effectively used. . Such liquid media can be broadly divided into aqueous media and non-aqueous media. Specific examples of the non-aqueous medium include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, isobutyl alcohol, pentyl alcohol, hexyl alcohol, and heptyl alcohol. Alkyl alcohols having 1 to 10 carbon atoms such as octyl alcohol, nonyl alcohol, and decyl alcohol; For example, hydrocarbon solvents such as hexane, octane, cyclopentane, benzene, toluene, and xylene; For example, carbon tetrachloride, trichloroethylene, and tetrachloride. Halogenated hydrocarbon solvents such as chloroethane and dichlorobenzene; for example,
Ether solvents such as ethyl ether, butyl ether, ethylene glycol diethyl ether, ethylene glycol monoethyl ether; for example,
Ketone solvents such as acetone, methyl ethyl ketone, methyl propyl ketone, methyl aluminum ketone, cyclohexanone; ethyl formate, methyl acetate, propyl acetate, phenyl acetate,
Examples include ester solvents such as ethylene glycol monoethyl ether acetate; alcohol solvents such as diacetone alcohol; and petroleum hydrocarbon solvents. The liquid media listed above are appropriately selected and used so as to satisfy the above-mentioned properties as well as compatibility with the recording material used and additives added as necessary. However, if necessary, two or more types may be mixed and used as long as an ink having desired characteristics can be prepared. Further, within the above conditions, these non-aqueous media and water may be mixed and used. Among the above-mentioned liquid media, water or a mixed solvent of water and alcohol is preferred in consideration of pollution, ease of availability, ease of preparation, and the like. The recording agent should be selected in relation to the liquid medium additive to prevent sedimentation and agglomeration in the nozzle and ink supply tank, as well as clogging of the transport pipe and nozzle due to long-term storage. needs to be used. From this point of view, in the present invention, it is preferable to use a recording agent that is soluble in the liquid medium.
Even a recording agent that is dispersible or poorly soluble in a liquid medium can be used if the particle size of the recording agent is made sufficiently small when dispersed in the liquid medium. The recording agent in the ink is appropriately selected to suit the recording conditions, and includes many conventionally known dyes and pigments. Dyes that can be effectively used in the present invention are those that can satisfy various characteristics of the prepared ink, and suitable examples include direct dyes as water-soluble dyes and basic dyes. , acid dyes, soluble architectural dyes, acid mordant dyes, mordant dyes, sulfur dyes as water-insoluble dyes, architectural dyes, alcohol-soluble dyes, oil-soluble dyes, disperse dyes, as well as thren dyes, naphthol dyes, and reactive dyes. Dyes, chromium dyes, 1:2 type complex salt dyes, 1:1 type complex salt dyes, azoic dyes,
Cationic dyes, etc. Other dyes are appropriately selected as desired and used by being dissolved or dispersed in the liquid medium used. On the other hand, many inorganic and organic pigments are used as pigments, and infrared rays are especially used as heat conversion energy to obtain thermal energy, which is the direct energy for ejecting ink from the orifice of the nozzle. In such cases, those with high infrared absorption efficiency are preferably used. Specific examples of such pigments include inorganic pigments such as cadmium sulfide, sulfur, selenium, zinc sulfide, cadmium sulfoselenide, yellow chlorine, zinc chromate, molybdenum red, Guiney green, titanium white, zinc white, Bengara, Chromium oxide green, red lead, cobalt oxide,
Barium titanate, titanium yellow, iron black,
Prussian blue, litharge, cadmium red, silver sulfide, lead sulfate, barium sulfate, ultramarine blue, calcium carbonate, magnesium carbonate. Lead white, cobalt violet,
Examples include cobalt blue, emerald green, and carbon black. Most organic pigments are classified as dyes, and they often overlap with dyes. The quantitative relationship between the liquid medium and the recording agent in the ink used in the present invention is determined by the thermal response, the stability of ink droplet formation, and the risk of nozzle clogging, drying within the nozzle, and application to the recording member. Depending on conditions such as bleeding and drying speed, the amount of recording agent is usually 1 to 50 parts by weight, preferably 3 to 30 parts, and most preferably 5 to 10 parts by weight, per 100 parts of the liquid medium.
It is desirable that it be designated as a department. When the ink is a dispersion system (a system in which the recording agent is dispersed in a liquid medium), the particle size of the dispersed recording agent is
It is determined appropriately depending on the type of recording agent, recording conditions, inner diameter of the nozzle, orifice diameter, type of recording member, etc., but if the particle size is too large, sedimentation of the recording agent particles will occur during storage. Non-uniformity of concentration may occur,
This is undesirable because the nozzle may become clogged or density unevenness may occur in the recorded image. Taking these matters into consideration, in the present invention, the particle size of the recording agent when used as a dispersion ink is usually
0.0001-30μ, preferably 0.0001-20μ, optimally
It is desirable that it be 0.0001 to 8μ. Furthermore, it is preferable that the particle size distribution of the dispersed recording agent be as narrow as possible, usually D±3μ, preferably D±3μ.
It is desirable that the particle diameter be 1.5μ (where D represents the average particle diameter). The ink used in the present invention is prepared using a liquid medium and a recording agent as basic components as described above.
Various additives may be added as desired to provide more pronounced recording properties. Examples of such additives include physical property regulators such as viscosity regulators, surface tension regulators, PH regulators, and resistivity regulators, as well as wetting agents and infrared absorbing exothermic agents. The viscosity modifier and surface tension modifier are mainly used to flow through the nozzle at a sufficient flow rate depending on the recording speed, to prevent the ink from going around the orifice of the nozzle, and to apply it to the recording member. It is added to prevent bleeding (spreading of the spot diameter) when the spot is exposed. As the viscosity modifier and the surface tension modifier, all commonly known agents can be used as long as they are effective and do not adversely affect the liquid medium and recording material used. Specifically, the viscosity modifiers include polyvinyl alcohol, hydroxypropyl cellulose,
Preferred examples include carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose, water-soluble acrylic resin, polyvinylpyrrolidone, and gum arabic starch. Surface tension modifiers preferably used in the present invention include anionic, cationic, and nonionic surfactants. Specifically, anionic surfactants include polyethylene glycol ether sulfate, ester salts, etc. Cationic systems include poly2-vinylpyridine derivatives and poly4-vinylpyridine derivatives; nonionic systems include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxydiethylene alkyl ester, polyoxyethylene sorbitan monoalkyl ester, and polyoxyethylene sorbitan monoalkyl ester. Examples include oxyethylene alkylamine. In addition to these surfactants, diethanolamine, probanolamine, amino acids such as morpholinic acid, basic substances such as ammonium hydroxide and sodium hydroxide, and substituted pyrrolidones such as N-methyl-2-pyrrolidone are also effective. used. Two or more of these surface tension adjusting agents may be mixed as necessary to the extent that they do not adversely affect each other or other constituent components so that an ink having a desired surface tension is prepared. You can use it as well. The additives for these surface tension adjusting agents are appropriately determined depending on the type, other constituent components of the ink to be mixed, and desired recording characteristics, but they are usually added to 1 part by weight of the ink. It is desirable that the amount is 0.0001 to 0.1 part by weight, preferably 0.001 to 0.01 part by weight. The PH adjuster is used in an appropriate amount to maintain the specified PH value in order to maintain the chemical stability of the prepared ink, for example, to prevent changes in physical properties due to long-term storage and to prevent sedimentation and aggregation of recording agents and other components. added. Specific examples of such PH adjusters include lower alkanolamines, monovalent hydroxides such as alkali metal hydroxides, ammonium hydroxide, and the like. As the humectant to be added to the ink used in the present invention, many commonly known wetting agents in the technical field related to the present invention are effective, but among these, thermally stable ones are particularly effective. are preferably used. Specific examples of such wetting agents include polyalkylene glycols such as polyethylene glycol and polypropylene glycol; Alkylene glycols containing; e.g. ethylene glycol methyl ether, diethyl glycol methyl ether,
Lower alkyl ethers of diethylene glycol such as diethyl glycol methyl ether and diethylene glycol ethyl ether; Glycerin; Lower alkoxy triglycols such as methoxy triglycol and ethoxy triglycol; N-
Vinyl-2-pyrrolidone oligomer; etc. are mentioned. These wetting agents are added in the required amount as desired to satisfy the desired characteristics of the ink, but the amount added is based on the total weight of the ink.
It is usually 0.1 to 10 wt%, preferably 0.1 to 8 wt%, and most preferably 0.2 to 7 wt%. Moreover, the above-mentioned wetting agents may be used alone or in combination of two or more types under conditions that they do not adversely affect each other. Additives such as those described above may be added in necessary amounts to the ink used in the present invention, as desired.
Furthermore, in order to obtain an ink film with excellent formability and film strength when attached to a recording member, resin polymers such as alkyd resin, acrylic resin, acrylamide resin, polyvinyl alcohol, and polyvinylpyrrolidone are added. It's okay. In the present invention, when infrared rays are used as an energy source, it is desirable to add an infrared absorbing exothermic agent to the ink in order to make the effect of the energy more effective. As an infrared absorbing exothermic agent,
Most of them are included in the above-mentioned recording materials, but dyes and pigments with high infrared absorption are particularly preferred.Specifically, the dyes include water-soluble nigrosine, modified water-soluble nigrosine, and water-soluble nigrosine. Alcohol-soluble nigrosine etc. are used as pigments such as carbon black, ultramarine blue, cadmium yellow,
Suitable examples include inorganic pigments such as red iron and chrome yellow, and organic pigments such as azo, triphenylmethane, quinoline, anthraquinone, and phthalocyanine pigments. When added separately from the recording agent, the amount of the infrared absorbing exothermic agent added is usually 0.01 to 10 wt%, preferably 0.1 to 5 wt%, based on the total weight of the ink. Especially if it is insoluble in the liquid medium used,
Depending on the particle size when dispersed, there is a risk of sedimentation, agglomeration, and nozzle clogging when the ink is stored or stagnate, so it is desirable to keep the amount to a minimum within the range that shows a noticeable effect. stomach. The physical properties of ink exemplified above have important relationships with the stability of ink droplet formation, responsiveness and fidelity to thermal energy effects, image density, chemical stability, ink fluidity within the nozzle, etc. Therefore, in the present invention, it is necessary to pay sufficient attention to these matters when preparing the ink. The above-mentioned physical properties of the ink that can be effectively used in the present invention are preferably as shown in Table 1 below. It is not necessary to satisfy the numerical conditions as shown in Table 1, but it is sufficient that some of these physical properties take values that satisfy the conditions in Table 1, depending on the required recording characteristics. However, specific heat, coefficient of thermal expansion, and thermal conductivity need to be defined by the values in Table 1. Of course, it goes without saying that the more of the above-mentioned physical properties of the prepared ink that satisfy the values shown in Table 1, the better the recording will be.

【table】

[Table] Here, the present invention will be explained in more detail with reference to Examples. Example 1 Ion exchange water 70g Propylene glycol 25g Direct Sky Blue 6B (CIDirect Blue 124410) 5g Polyoxyethylene sorbitan monooleate
0.1 g was stirred until sufficiently homogeneous and filtered to obtain an ink. The ink prepared with the above composition was transferred to a beaker and stored in a desiccator connected to a rotary pump with a thick rubber tube. Next, the rotary pump was operated to evacuate the desiccator, and degassing was performed for 1 hour. The ink thus degassed was divided into 10 equal parts, each of which was transferred into a polyvinyl chloride cassette container and sealed. Next, as shown in Table 3 below, 9 of the 10 cassette containers filled with ink as described above are injected with N ₂ gas, air, and CO ₂ gas in predetermined amounts. Samples A-1 to A-9 were prepared by dissolving them (temperature during dissolution was 25%°C). A comparison sample was prepared by performing only degassing treatment without actively dissolving gas (sample B-1). Samples A-1 to A-9, B- prepared as above
A glass nozzle having an orifice for ejecting ink using 1, and an electrothermal converter (heating element) provided surrounding and in contact with a part of the nozzle.
A recording head consisting of (10 nozzles/mm)
When jet recording was performed on one side of B4 size according to the recording conditions shown in Table 2 using a recording device (on demand type) having a recording head (hereinafter simply referred to as a recording head), the recorded image on the recording member was The results shown in Table 3 were obtained.

【table】

[Table] As the amount of dissolved gas was increased, images of good quality began to be obtained, and as the amount of dissolved gas approached the saturated amount, images of extremely excellent quality began to be obtained. Example 2 Inks having the following compositions were prepared and each was degassed using the same method as in Example 1. Thereafter, air was dissolved in each ink at 30°C until saturation was reached, and Sample C was prepared. -1 to C-4. C-1; Ion-exchanged water 60g n-propyl alcohol 35g Diapanol Fast Black Conc.
5g C-2; Ion exchange water 47g Glycerin 45g Dialumina surbin B 8g C-3; Ethanol 92g Dialumina surbin B 8g C-4; Isopar E 98g Acetone 10g Dianics Fastro Yellow YL
2g Using each of these samples, B was recorded using the same recording device as in Example 1 according to the recording conditions in Table 4.
- When jet recording was performed on the entire surface of the 4-size paper, the recorded images on the recording member obtained for each sample were of extremely excellent quality with no stains on the background (white area). Ta.

[Table] Example 3 Zapon Fast Yellow 3RE (CISolvent
Orange 45, CI, 11700) 2g to 10g ethanol
This solution was uniformly mixed with 98 g of Isopar H to prepare an ink. The ink prepared with the above composition was degassed for 1 hour in the same manner as in Example 1. The degassed ink was divided into two halves, and Ar gas was dissolved in one half until it reached saturation, and then immediately transferred to a polyvinyl chloride cassette container and sealed (sample D). ). The remaining one was degassed and placed in a similar cassette container and sealed (sample E). Using Samples D and E thus obtained, Jerk recording was performed using the same recording apparatus as in Example 1 according to the recording conditions shown in Table 5.

[Table] Form a B-4 size image under the conditions listed in Table 5,
I made many records. As shown in the table below, excellent images were obtained even under low energy driving under conditions B and C, and energy savings were achieved.

[Table] * Example of continuous recording number 4 5 g of Rhodamine B (CIBasic Violet 10, CI45170), 120 g of glycerin, and 80 g of ion-exchanged water were thoroughly mixed to create a uniform red ink. The ink prepared with the above composition was degassed for 2 hours in the same manner as in Example 1. This degassed ink was divided into two halves, and after dissolving air in one half until it reached saturation, it was immediately transferred to a polyvinyl chloride cassette container and sealed (sample F). ). The remaining one was placed in a similar cassette container and sealed while being degassed (Sample G). Using the samples F and G thus obtained, jet recording was performed using the same recording apparatus as in Example 1 according to the recording conditions shown in Table 6.

【table】

[Table] Table 7 shows the results of continuous recording under various frequency conditions. As can be seen from the results, according to the present invention, excellent images without satellite dots were continuously obtained even in high frequency recording.

Claims (1)

[Claims] 1. In an ink jet recording method in which thermal energy is applied to ink to form ink droplets and recording is performed using these ink droplets, the ink is mainly composed of a recording agent and a liquid medium that dissolves or disperses the recording agent, An inkjet recording method characterized in that 0.01 ml or more of gas is dissolved in 1 ml of the inkjet ink, calculated under conditions of 0° C. and 760 mmHg.