JPH1052924A - Ink jet recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize no development of poor printing not only at early stage but also even under the changes of temperature and with time and the improvement of the reliability of a recording device by a method wherein an ink tank in contact with liquid ink is made of a resin containing a specified aliphatic acid and/or aliphatic acid derivatives and/or synthetic rubber. SOLUTION: When insoluble matter is produced by reacting the additive component in the resin or synthetic rubber, of which an ink tank contacting with ink is made and which is eluted in the ink, with the compositional component of the ink, the insoluble matter plugs the fine passages, a filter, orifices and the like in an ink jet printer and prevent the ink from showing its fluidity, resulting in causing poor printing and blurred printing. Thus, the insoluble matter is prevented from being produced by confining the total amount of the aliphatic acid such as calcium stearate and its derivatives in the fat or rubber, of which the ink tank is made, to 10-100ppm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus using a liquid ink as a recording medium.

[0002]

2. Description of the Related Art Ink-jet printers realize noiseless, high-speed printing, high-quality printing and color printing by various ink droplet jetting methods such as continuous jet, impulse jet, and thermal jet. Because of the technology for printing by jetting from a fine nozzle orifice of about 10 to 100 μm, very clean and stable characteristics ink is required so that the ink can flow stably through the fine orifice and the fine flow path. for that reason,
Ink production was performed in a clean room where generation of dust and dust was suppressed as much as possible, and the ink was finely filtered with a membrane filter of 1 μm or less to maintain clean ink. On the other hand, the ink tank containing the ink that has been cleaned in such a process is also subjected to precision cleaning using ultrapure water before storing the ink so as not to mix dust, dirt, and foreign matter into the ink. I was

[0003]

However, according to the above-mentioned prior art, the ink in the ink tank can be kept clean only at the initial stage. Additives in the material constituting the ink tank elute into the ink and cause a chemical reaction with the ink composition, thereby forming an insoluble matter in the ink, and the insoluble matter in the ink jet printer is changed. There is a problem that ink flow can be prevented in a fine path, a filter, an orifice, and the like, resulting in poor printing of a printer and blurring of printing.

Therefore, the present invention solves such a problem, and the stalk of the ink tank having the liquid ink is not limited to the initial state but also to the temperature change and the aging change. Another object of the present invention is to provide an ink jet recording apparatus such as an ink jet printer which does not cause printing failure or blurring of the pudding.

[0005]

According to the present invention, there is provided an ink jet recording apparatus comprising: 1) an ink jet recording apparatus having an ink tank and a liquid ink in the ink tank, wherein the liquid ink has a sodium ion concentration of 0.001 to 0.2; % By weight. 2) In an ink jet recording apparatus having an ink tank and a liquid ink in the ink tank, the liquid ink has a sodium ion concentration of 0.001 to 0.2% by weight.
Wherein the material of the ink tank is a resin and / or synthetic rubber containing fatty acids and / or fatty acid derivatives. 3) In an ink jet recording apparatus having an ink tank and liquid ink in the ink tank, the total amount of fatty acids or fatty acid derivatives in the material forming the ink tank is 10 to 100 ppm.

[0006] The ink system of the ink jet recording apparatus is the first.
As shown in FIG. 1A, a replaceable ink tank 12 for storing the ink 11 and an ink supply pipe 13 for connecting the ink 11 to the print head 14 are basically constituted, and the ink in the ink tank 12 is reduced. , Ink tank 12
Is disconnected from the ink supply pipe 13, the ink tank 12 having the full ink is connected to the ink supply pipe 13, and the ink 11 can be supplied to the print head 14 again.

[0007] As shown in FIG.
In order to prevent foreign matter or insoluble matter causing clogging of the nozzle orifice 15, such as dust, from flowing into the nozzle 4, the reliability of the printer can be improved by providing the filter 16 in the ink path.

Further, as shown in FIG. 2, there is an ink system in which the print head 14 is supplied with the ink 11 directly from the integrated ink tank 21 and the ink supply tube 13 is omitted.

An ink-based member of an ink-jet printer must have ink resistance because it comes into contact with ink. In view of the requirements, generally available materials include polyolefin resin, polyvinyl chloride, polyvinylidene chloride, silicone resin, ethylene-vinyl acetate copolymer, ABS resin, polyacetal, nylon, unsaturated polyester resin, PET, and aramid. Resin materials such as resin, styrene butadiene rubber (SBR), butadiene rubber,
Chloroprene, nitrile rubber, butyl rubber, EPDM,
There are synthetic rubbers such as urethane rubber, silicone rubber, acrylic rubber, epichlorohydrin rubber, and fluoro rubber. To these resins and synthetic rubbers, in addition to chemical substances constituting themselves, various additives such as stabilizers, UV absorbers and antioxidants are added in appropriate amounts depending on purposes.

The present inventor has determined that the additive component contained in the resin or synthetic rubber constituting the ink tank is eluted into the ink, and the eluted component reacts with the ink component to form an insoluble substance. Discovered and led to the present invention. That is, if the ink tank 12 containing the ink 11 is not used for a long time, or is kept under a condition higher than room temperature, the fatty acid contained in the resin or synthetic rubber constituting the ink tank 12 is reduced. When fatty acids and derivatives are eluted into the ink and returned to room temperature, they precipitate again and form insolubles, or the sodium ions contained in the ink react with the eluted substances to form insolubles of fatty acid sodium. To pinch the filter 16 and nozzle orifice 15,
This prevented the flow of ink. In particular, when the additive in the resin or the synthetic rubber is stearic acid, stearic acid amide, or a metal salt of stearic acid, sodium stearate is generated, and this compound is formed into a filamentous or needle-like elongated crystal. Easy to clog the ink flow path,
Easy to prevent ink flow. This phenomenon occurs remarkably when the ink container containing the ink is left at a high temperature of 40 ° C. or more for one day or more. This is because stearic acid, stearic acid amide, and metal stearate in resin and synthetic rubber are easily melted at high temperatures, and the polymer matrix of resin and synthetic rubber earthquakes undergo molecular vibrations due to temperature rise. This is considered to be because elution of the stearic acid and its derivatives present therein becomes large. When the pH of the ink is further increased, the effect is further enhanced.

The amount of the fatty acid or derivative thereof contained in the resin or synthetic rubber constituting the ink container varies depending on the type of the resin or rubber and the grade of the same type. In particular, polyolefin resins typified by polyethylene and polypropylene are materials that are suitable for ink containers and have high chemical resistance, are inexpensive and can be processed into bags. In the resin, the fatty acid or a derivative thereof is added as a stabilizer at the time of polymerization or as a slip agent for preventing adhesion to a roller when processing into a film. As resin acids and fatty acid derivatives used for stabilizers and slip agents, those having 8 to 22 carbon atoms are generally used, and among them, stearic acid, Ca, Al, Mg, Zn
Of stearic acid metal salt (hereinafter stearic acid (Ca, A
1, Mg, Zn)), stearic acid amide, pehenic acid, behenic acid (Ca, Al, Mg, Zn), stearic acid amide, oleic acid, oleic acid (Ca, A
(1, Mg, Zn) oleic acid amide, erucic acid, erucic acid (Ca, Al, Mg, Zn) erucic acid amide, and the like.

Particularly, in the case of a polyethylene film, linear low density, polyethylene (LLDPE)
There are many types, such as low-density polyethylene (LDPE), medium-density polyethylene (MDPE), and high-density polyethylene (HDPE), and the amounts of fatty acids and derivatives thereof added to each vary. Other materials that contain fatty acids and their derivatives in the material of the ink container include vinyl chloride, nylon, polyacetal, ethylene-vinyl acetate, ABS
Examples include resin and most synthetic rubbers.

On the other hand, ink used in an ink jet printer has good handleability and does not cause clogging of a nozzle orifice due to drying of the ink itself, and low ink consumption due to high-speed response of ink droplets ejected from an ink ejection head. A property such as a viscous fluid is required, and a water-based water-based ink is generally used. Therefore, the ink contains pigment components such as water-soluble direct dyes, acidic dyes, and basic dyes, and wet components that prevent the ink from drying even when water evaporates. In particular, direct dyes and the like, which are coloring components, have a large amount of sodium sulfonate in the molecule to increase the solubility of water, furthermore, sodium chloride used in the salting step in the dyeing step, and nitrous acid in the diazotization step. Sodium, other sodium acetate, sodium carbonate, sodium hydroxide and sodium sulfate are contained in the dye. Therefore, the sodium ions contained in the ink and the fatty acids and derivatives thereof contained in the ink tank are eluted into the ink due to the temperature and the like to form sodium fatty acids, which is a cause of preventing the fluidity of the ink.

The inventor of the present invention filled a bag made of a low-density polyethylene film, which is often used among polyolefin resins, with aqueous solutions having different sodium ion concentrations containing 1% KOH to accelerate dissolution from the bag, and sealed the bag. Thereafter, the product was left in an environment of 70 ° C. for about 10 days, and then kept at room temperature for 5 days, after which the product in the solution was observed. A low-density polyethylene bag having a thickness of 60 μm was used as a condition, and the amount of sodium ions was 0.1 wt% and 0.15 w
A NaCl aqueous solution having a concentration of t%, 0.2 wt%, 0.25 wt%, and 0.3 wt% is subjected to heat sealing in a liquid so that no air bubbles remain in the bag.
In bags containing wt% and 0.3 wt% of NaCl, generation of thread-like crystals was observed. The filament was analyzed by an infrared spectrophotometer and an X-ray microanalyzer, and was found to be sodium stearate. Therefore, even if the resin or synthetic rubber constituting the container contains a fatty acid or a derivative thereof in the ink container, if the sodium ion concentration of the ink in the container is 0.2 wt% or less, fluidity can be prevented from the ink container. You don't have to produce the sodium fatty acid that causes it.

On the other hand, if the sodium ion concentration in the ink is too low, the dye is likely to associate in an aqueous solution,
Although the cause is not clear, an ink having a high association property of the dye is not preferable because it lacks continuous ink jetting stability. Therefore, the sodium ion concentration in the ink is 0.00
1 to 0.2 wt% is appropriate.

The recording ink according to the ink jet printer of the present invention contains water, a water-soluble dye and a wetting agent as main components, and the total concentration of sodium ions contained in each composition is 0.001 of the total amount of the ink. ０．２0.2 wt%.

With respect to water, ultrapure water is used in order to minimize the concentration of sodium ions. Ultrapure water can be obtained by treating ordinary tap water with a known method such as a reverse osmosis membrane or an ion exchange resin.

The water-soluble dye generally contains a large amount of sodium. As the cause, sodium chloride used in the salting-out step of the dye, sodium nitrite in the diazotization step, sodium acetate, sodium carbonate, sodium hydroxide, sodium sulfate in other steps, the dye produced It is because it is included in. Also, the water-soluble dye itself often contains a sodium sulfonate group in the molecule, and most of the generally available water-soluble dyes are
5% or more is contained as sodium in the dye. Therefore, in order to use the sodium compound in the recording ink of the present invention, the use of these sodium compounds is reduced in the production stage, and sodium ions can be reduced by using other alkali metal compounds such as potassium chloride. Even when the above-mentioned sodium compound is used, the cation exchange resin, for example, a strongly acidic cation exchange resin such as Amberlite 120 series (trade name of Organo Co., Ltd.) or Dowex 50W (Dow Chemical trademark) is converted to H-type. Thus, sodium ions can be reduced by passing an aqueous dye solution through the exchange resin.

As the water-soluble dye used in the present invention, direct dyes, acid dyes and basic dyes having a color index can be used. Can be adjusted to the sodium ion concentration. Since the dye is a coloring component of the recording ink, when printed on a recording medium, sufficient contrast is necessary.If the dye concentration is too high, clogging due to drying and precipitation occurs in the nozzle portion of the inkjet head. , 0.5 to 10 parts by weight is optimal.

The wetting agent is an important component for preventing the recording ink from drying at the nozzle of the ink jet head. In the recording ink of the present invention, a water-soluble organic solvent can be used, and among them, polyhydric alcohols, and ether derivatives, ester derivatives, water-soluble amines, and nitrogen-containing cyclic compounds of the polyhydric alcohols are suitable. . In particular,
Polyhydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, polyethylene glycol, glycerin, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether,
Alkyl ether derivatives of polyhydric alcohols such as diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, and triethylene glycol monomethyl ether; ethylene glycol monomethyl ether acetate; diethylene glycol monoethyl ether acetate; Ester derivatives,
There are water-soluble amines such as (mono-di-tri) ethanolamine and polyoxyethyleneamine, and nitrogen-containing cyclic compounds such as N-methyl-2-pyrrolidone. Since these water-soluble organic solvents do not contain sodium ions, there is no particular need to purify them. However, water-soluble organic solvents that require the use of sodium compounds in the synthesis process should be purified. As the amount of the organic solvent added, the effect increases as the amount increases in order to prevent drying of the recording ink. However, the addition of a large amount is not preferable because the viscosity of the recording ink also increases.
In general, the viscosity of the ink greatly affects the ejection cycle of ink droplets. When the viscosity is high, the ejection cycle does not increase and the ejection characteristics become unstable. Therefore, the ink viscosity is 50
mPa · s or less is preferable, and considering this viscosity range, 5 to 80 parts by weight of a water-soluble organic solvent can be added.

The recording ink used in the ink jet printer of the present invention has a pH value as described in Japanese Patent Application Laid-Open No. 56-57862. It can be adjusted to 12-14.
In this case, an alkali metal hydroxide is used to increase the pH value. In the present invention, lithium hydroxide and potassium hydroxide are appropriate, and sodium hydroxide cannot be used.

Other additives such as a preservative, a fungicide, a chelating agent, a pH adjuster and the like can be added as necessary. However, these additives are mainly sodium compounds and are preferably added in small amounts.

Further, the present inventor has focused on the reaction between the fatty acid and its derivative and sodium ions of the ink, and reduced the fatty acid and its derivatives contained in the resin and synthetic rubber constituting the ink tank, so that the ink contained in the ink was reduced. It was confirmed that even when sodium ions were contained in an amount of 0.2 wt% or more, generation of insolubles could be suppressed. As an experiment, 1w
0.5 wt% in sodium ion concentration containing t% KOH
% NaCl aqueous solution, using a polyethylene bag containing 5, 10, 50, 100, and 200 ppm of Ca stearate, 100 cc of the NaCl aqueous solution was heat-sealed in a liquid such that no air bubbles remained, and 70 ° C. Was left for 10 days at room temperature, and then left at room temperature for 3 days, the bag was broken, the liquid was taken out, and filtered with a metal filter having a pore size of 10 μm. As a result, insolubles were generated only in the bag containing 200 ppm of Ca stearate. In addition, the bag containing 5 ppm has a liquid dripping from the heat seal part,
At this concentration, since the sealing strength is weak, 10 to 100 pp
It was found that the use of a polyethylene bag having a calcium stearate concentration of m could suppress the generation of insolubles even when sodium ions were contained in an amount of 0.2 wt% or more, and that the sealing strength was practical. In other words, the generation of insolubles varies depending on the composition and sodium concentration of the ink in the ink tank, but the total amount of fatty acids such as Ca stearate and its derivatives in the fats and rubber materials constituting the ink tank is 10%.
If it is 100 ppm, there is no insoluble matter generation that can prevent the flow of the ink system of the ink jet printer, and there is no practical problem.

[0024]

【Example】

Example 1 C.I. I. Direct Black 38 10% by weight Ultrapure water 90% by weight 100 g of the above aqueous solution was passed through an ion exchange column filled with H-type strongly acidic ion exchange resin Amberlite 120B to remove sodium ions. I. Dir
Thus, a purified 10% aqueous solution of ect Black 38 was obtained. The aqueous solution was adjusted so that Na was exchanged for H and the pH was low, and the pH was adjusted to 10 with an aqueous KOH solution. Using this liquid, an ink having the following composition was prepared. Crystals, sodium 0.1%, potassium 0.4% and chlorine 0.5% of this ink were measured by ion chromatography.

C. I. Purified 10% aqueous solution of Direct Black 38 12 parts by weight Glycerin 20 parts by weight Ultrapure water 68 parts by weight After blending, the mixture was filtered through a 1 μm Millipore membrane filter, degassed under reduced pressure, and put into an ink bag made of polyethylene film. And 150 g of the ink was placed in the bag, and heat sealing in liquid was performed to prevent air from entering the bag to obtain an ink tank. The ink tank was left at 70 ° C. for 120 hours,
After leaving at room temperature for 3 days, the ink tank was connected to an IP-130K inkjet printer (manufactured by Seiko Epson Corporation) to perform printing. When 10 packs of the ink tank were used, a 30 μm nylon filter in the ink path was examined. As a result, no filter was clogged and the filter was good.

Comparative Example 1 The 10% aqueous dye solution of Example 1 was not passed through the ink exchange tower.
It was adjusted with the KOH aqueous solution of Example 1 and a colleague. Using the adjustment liquid, an ink having the same composition as in Example 1 was obtained. As a result of measurement by ion chromatography, sodium was 0.5%, potassium was 0.4%, and chlorine was 0.5%.

After the adjustment, an ink tank was prepared in the same manner as in Example 1. After the ink tank was left under the same conditions, printing was performed. Examination of the filter in the ink path revealed that the filter was mostly clogged and was magnified by infrared spectroscopy and electron microscopy to find sodium stearate crystals. The printing failure was due to the clogging of the filter, which prevented the flow of the ink, and caused the supply failure of the ink.

Embodiment 2 C.I. I. In synthesizing Direct Black 154, coupling was performed using sodium nitrite,
In other steps, synthesis was performed without using any sodium compound. After synthesis, the dye is acid-deposited with hydrochloric acid and then KO
H solution, and the following ink was prepared with the 10% aqueous solution.

The ink was measured by ion chromatography and found to be 0.03% sodium, 0.6% potassium and 0.3% chlorine.

The above C.I. I. Direct Black 154 10% aqueous solution 15 parts by weight Polyethylene glycol # 300 30 parts by weight Ultrapure water 55 parts by weight As a result of performing the same evaluation as in Example 1, the filter in the ink path was not clogged and the printing state was good. .

Example 3 Using the dyestuff of Examples 3-1 to 3-8 in which sodium was reduced by the same treatment as in Example 1 or 2, 3-1 to 3-
The ink shown in No. 8 was prepared. 3-10-3 as comparative examples
-13, a commercially available dye was prepared as an ink as it was.
Sodium, potassium and chlorine were measured by ion chromatography.

[0032]

[Table 1]

[0033]

[Table 2]

[0034]

[Table 3]

[0035]

[Table 4] Table 1 shows the results of the same evaluation as in Example 1.

[0036]

[Table 5] As shown in Table 1, when the sodium ion concentration in the ink was 0.2% or less, no filter clogging occurred. The potassium ion concentration and the chlorine ion concentration hardly contributed to filter clogging.

Example 4 A similar experiment was performed by changing the ink bag used for the evaluation in Example 1 to the material shown in Table 2. The ink of Example 1 and the ink of Comparative Example 1 were used, and the results in Table 2 were obtained.

[0038]

[Table 6] …: Printing condition is good even with 10-pack printing ×: Printing condition is bad before printing of 10-pack and filter clogged Ink with sodium ion concentration of 0.2% or less
Filter clogging was not performed on any of the materials No. 2, but all inks having a sodium ion concentration of 0.5 wt% clogged the filter.

Example 5 The above Examples 3-1 to 3-8 and Comparative Examples 3-10 to 3-13
Are sealed in the ink tanks of Examples 5-1 to 5-8 shown in Table 3 and the ink tanks of Comparative Examples 5-10 to 5-13, and are sealed. After leaving for 3 days at room temperature,
The ink was filled in a -130K inkjet printer (manufactured by Seiko Epson Corporation), and all 150 cc of the ink in each ink tank was printed. Table 4 shows the result of examining the degree of clogging of the filter in the ink system flow path after printing. The filter is made of a nylon mesh having 30 μm holes, and has an area of about 3 cm ³ .

[0040]

[Table 7]

[0041]

[Table 8] In the ink tanks 5-1 to 5-8 of the example, there is no filter clogging at all, and even if there is an eluted component from the container and a deposit of ink, it is considered that all of the ink has passed through the filter and there is no practical problem at all. On the other hand, 5-10-5-13
In the ink tank, an aggregate of thread-like materials is formed in a film shape,
5-10, 5-12, 5-
As for No. 13, printing failure occurred. Regarding 5-11, it was thought that if a similar ink tank was continuously used, the filter would be similarly clogged, resulting in poor printing.

Example 6 In a polyethylene bag containing 50 ppm of a slip agent as a fatty acid-based stabilizer, 200 cc of an ink having the following composition was placed, and the ink was hermetically sealed by heat sealing in liquid so as not to leave air bubbles. The ink container was allowed to stand at 10 ° C. for 10 days, then at room temperature for 3 days, and then an IP-130K inkjet printer (manufactured by Seiko Epson Corporation).
When printing was performed with the ink filled, the flow of the ink was not prevented. After printing 200 cc, the nylon 30 μm filter in the printer flow path was examined and found to be good without any clogging. .

Composition C. I. Direct Black 154 3 wt% Polyethylene glycol # 400 20 wt% Diethylene glycol 10 wt% Ultrapure water 67 wt%

Comparative Example 6 In a polyethylene bag containing 200 ppm of a fatty acid-based stabilizer slip agent, 200 cc of the ink having the composition shown in Example 6 was added.
, And the same experiment as in Example 6 was performed. As a result, 20
Printing failure occurred before 0 cc printing, and a film-like nylon 30 μm filter in the flow path of the printer was clogged. As a result of the analysis, it was found that the mixture was a mixture of erucamide and oleamide, and it was presumed that the slip agent on the surface was peeled off.

Example 7 The same experiment as in Example 6 was conducted by putting 200 cc of an ink having the following composition into a polyethylene bag containing 100 ppm of a fatty acid-based stabilizer and a slip agent. As a result, 200
Even after cc printing, the filter was good without clogging of the filter.

C. I. Direct Black 154 2 wt% Glycerin 20 wt% Triethylene glycol 5 wt% Potassium hydroxide 1 wt% Ultrapure water 72 wt%

Comparative Example 7 In a polyethylene bag containing 200 ppm of a fatty acid-based stabilizer and a slip agent, 200 parts of the ink of the composition shown in Example 7 was added.
The same experiment as in Example 7 was carried out. As a result, 2
Printing failure occurred before printing at 00 cc, and a film-like nylon 30 μm filter in the printer flow path was clogged. As a result of the analysis, it was found that sodium stearate was the main component, the stabilizer in the polyethylene was eluted, and the dye in the ink (CI Direct Black) was used.
k 54) was presumed to have been produced by the reaction with Na.

[0048]

As described above, according to the present invention, when the ink tank is left at a high temperature or for a long period of time, fatty acids and derivatives thereof contained in the ink tank member elute into the ink in the ink tank. And re-precipitate in the ink,
Since it does not react with sodium ions in the ink component to generate insolubles, the flow of the ink is stable in the ink system of the ink jet recording device, and the ink jet recording device such as an ink jet printer can reduce the printing defect and the print fading. This does not occur, and has the effect of improving the reliability of the ink jet recording apparatus.

[Brief description of the drawings]

FIG. 1A is a simplified diagram showing an ink system of an inkjet printer. (B) is a simplified diagram showing an ink system of an ink jet printer having a filter in the ink system.

FIG. 2 is a simplified diagram showing an ink system in which a print head and an ink tank are integrated.

[Explanation of symbols]

 11 ink 13 ink supply pipe 14 print head

Claims (3)

[Claims] 1. An ink jet recording apparatus for storing ink in an ink tank, wherein the material of the ink tank that contacts the ink is 10
An ink jet recording apparatus comprising a resin and / or synthetic rubber containing from 100 to 100 ppm of a fatty acid and / or a fatty acid derivative. 2. The ink jet recording apparatus according to claim 1, wherein said fatty acid is at least one selected from the group consisting of stearic acid, behenic acid, oleic acid, and erucic acid. 3. The method according to claim 2, wherein the fatty acid derivatives are C
a, Al, Mg, Zn salt, stearic acid amide, Ca, Al, Mg, Zn salt of behenic acid, behenic acid amide,
The oleic acid Ca, Al, Mg, Zn salt, oleic acid amide, erucic acid Ca, Al, Mg, Zn salt, and at least one selected from the group consisting of erucic acid amide. Inkjet recording device.