JP2710138B2 - Ink for ink jet - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ink-jet ink, and more particularly to a coated paper specially adjusted for an ink-jet printing.
In addition, it has very good fixability to uncoated paper such as copy paper, report paper, notebooks, stationery, bond paper, continuous slip paper, and so-called plain paper which are generally used in offices and homes, so-called plain paper. The present invention relates to an inkjet ink capable of high-quality recording.

(Prior Art) In the past, ink jet inks of various compositions have been reported. In particular, copy paper, report paper,
Detailed research and development have been made from various aspects such as ink composition and physical properties so that good recording can be performed on plain paper such as notebooks and stationery.

For example, in general, ink contains a high-boiling organic solvent such as glycol for the purpose of preventing drying and preventing clogging, etc.When recording is performed on plain paper having a high degree of size using such an ink. In some cases, the ink hardly penetrates into the paper and the drying property of the recording part is poor. Was.

On the other hand, Japanese Patent Application Laid-Open No. 55-29546 proposes a method of adding a large amount of a surfactant to the ink in order to increase the permeability of the ink into the inside of the paper. However, in this case, bleeding occurs extremely depending on the type of paper, or when the ink is filled in the ink jet head, the ink recedes from the orifice surface depending on the structure of the head, and the ink is not ejected. On the contrary, there were problems such as the entire orifice surface being wet and the ink not being ejected.

Further, Japanese Patent Application Laid-Open No. 56-57862 proposes a method for making the pH of the ink highly alkaline, but this method is dangerous when the ink is touched by hand, and has a certain size. Bleeding on paper using the agent, for example, neutral paper,
There are drawbacks that both may not be good in terms of drying properties.

Japanese Patent Application Laid-Open No. 55-145774 discloses an ink containing an aliphatic monohydric alcohol to prevent freezing due to a drop in freezing point of the ink. Is limited to 5-20% by weight.

According to studies by the present inventors, the use of alcohol as a penetrant is itself an extremely effective means in terms of suppressing bleeding and promoting fixation. However,
If the addition amount exceeds 5% by weight, irregular bleeding generally tends to occur, which is not a level that can be sufficiently used for the purpose of printing quality as intended in the present invention. This tendency is considerably reduced when a lower alcohol having about 3 carbon atoms or less is used, but in this case, since the vapor pressure of the alcohol is high, the alcohol evaporates from the orifice of the head, and the like.
The ink composition tends to change. This phenomenon is particularly remarkable when the ink is used for a type of ink jet head having an air communication hole, and is a serious problem. Further, in a system in which the amount of alcohol exceeds 5% by weight, in the case of an aqueous medium, the dissolution or dispersion of the dye becomes unstable, and the storage stability and clogging resistance of the ink deteriorate.

Although various improvements other than those described above have been attempted, inks that sufficiently solve all of the aforementioned problems such as bleeding, drying properties, clogging resistance, and storage stability have been known so far. There is no present.

(Problems to be Solved by the Invention) Accordingly, an object of the present invention is to provide ink for recording on uncoated paper such as copy paper, report paper, notebooks, and stationery commonly used in offices and the like, so-called plain paper. It is an object of the present invention to provide an ink-jet ink (sometimes simply referred to as “ink”) that solves the problems of blurring of ink and slow drying of recorded matter.

Another object of the present invention is to provide an ink-jet ink which has high safety even in use in offices and homes, and is less likely to undergo a composition change due to evaporation or the like even when left for a long period of time.

Still another object of the present invention is to provide an ink which is less likely to cause clogging in nozzles of an ink jet head and which has excellent reliability such as storability.

(Means for Solving the Problems) The above object is achieved by the present invention described below.

That is, the present invention provides a composition comprising a dye and a liquid medium, wherein the liquid medium contains at least 50 to 95% by weight of water and
An inkjet ink containing 0.001 to 4% by weight of an aliphatic monohydric alcohol having 9 or 10 carbon atoms.

(Action) In order to improve the bleeding, drying property and permeability of the ink on paper, the present inventors have conducted intensive studies on various ink compositions, and found that 0.001 to 4% by weight together with 50 to 95% by weight of water. The ink containing an aliphatic monohydric alcohol having 9 or more carbon atoms is balanced in terms of bleeding and permeability,
Further, the present inventors have found that there is no adverse effect on the anti-clogging property and that the substance is highly reliable, which has led to the present invention.

That is, according to the study of the present inventors, regarding the bleeding and penetrability of the ink on the paper, when the surfactant used in the ordinary ink is used, depending on the type of paper, the case where it is good and the case where it is not good Are mixed, and it is difficult to obtain stable recording. On the other hand, when the liquid medium system used in the present invention is used, it is possible to obtain an extremely good result that stable recording with little difference in quality depending on the type of paper can be obtained.

The reason for this is that the bleeding and permeability of the ink are largely governed mainly by the phenomenon of wetting at the interface between the ink droplet and the paper, but when a surfactant is used, the ink liquid adhering to the paper Good results cannot be obtained due to the difference in the property of wetting between the surface portion and the inner portion of the droplet, whereas in the case of the ink of the present invention, such a thing is unlikely to occur, and further, the ink of the present invention This is probably because the affinity between the ink and the sizing agent added to the surface or inside of the paper is in an exquisite balance as an inkjet ink that can be used for plain paper.

(Preferred Embodiment) Next, the present invention will be described in more detail with reference to preferred embodiments.

The compound used in the present invention and which mainly characterizes the present invention is an aliphatic monohydric alcohol having 9 or 10 carbon atoms, which can be obtained by a conventionally known method. Preferred specific examples of the above compound are as follows, but the present invention is not limited to these specific examples.

Compound Example 1: CH ₃ (CH ₂ ) ₈ OH Compound Example 2: CH ₃ (CH ₂ ) ₆ CH (OH) CH ₃ Compound Example 3: CH ₃ (CH ₂ ) ₅ CH (OH) CH ₂ CH ₃ Compound Example 4: CH ₃ (CH ₂ ) ₄ CH (OH) (CH ₂ ) ₂ CH ₃ compound example 5: [CH ₃ (CH ₂ ) ₃ ] ₂ CHOH compound example 6: [(CH ₃ ) ₂ CHCH ₂ ] ₂ CHOH Compound Example 7: (CH ₃ ) ₃ CCH ₂ C (CH ₃ ) (CH ₂ ) ₂ OH Compound Example 8: (CH ₃ ) ₃ CCH ₂ C (CH ₃ ) ₂ CH ₂ OH Compound Example 9: CH ₃ (CH _{3 2} ) ₉ OH compound example 10: CH ₃ (CH ₂ ) ₇ CH (OH) CH ₃ compound example 11: CH ₃ (CH ₂ ) ₆ CH (OH) CH ₂ CH ₃ compound example 12: CH ₃ (CH ₂ ) ₅ CH (OH) (CH ₂ ) ₂ CH ₃ Compound Example 13: CH ₃ (CH ₂ ) ₄ CH (OH) (CH ₂ ) ₃ CH ₃ Specific examples are particularly preferable as a result of intensive studies by the present inventors. Was selected as the correct one.

The aliphatic monohydric alcohols having 9 or 10 carbon atoms as described above can be used alone or as a mixture, and the amount added to these inks varies depending on the pigment used, other liquid medium components used in combination, and the like. About 0.001 to 4% by weight, preferably 0.005 to 3% by weight, more preferably 0.01 to 2% by weight in the ink
It is the ratio that occupies.

When the amount of the aliphatic monohydric alcohol having 9 or 10 carbon atoms is less than 0.001% by weight, there is no effect on the permeability of the ink, and when it exceeds 4% by weight, the surface tension of the ink decreases. Therefore, depending on the paper, bleeding easily occurs, and the print quality is reduced.

The proportion of water in the ink which is an essential component of the ink of the present invention is 50 to 95% by weight, preferably 55 to 95% by weight.
The proportion occupies 95% by weight, more preferably 60 to 95% by weight. When the amount of water is less than 50% by weight, the proportion of the organic solvent is large, and the paper curls or the print quality on plain paper or the like is significantly reduced. On the other hand, if the amount of water exceeds 95% by weight, the ejection stability of the ink from the nozzle office and the clogging resistance after the printing is temporarily stopped are significantly deteriorated.

The ink of the present invention comprises 50 to 95% by weight of water together with a pigment,
It is characterized by containing 0.001 to 4% by weight of an aliphatic monohydric alcohol having 9 or 10 carbon atoms, and may also be used in combination with other common organic solvents used in conventionally known inks. However, as in the case of amides such as formamide, dimethylformamide and dimethylacetamide, the number of carbon atoms is 9 or more.
Some of them cannot be used due to poor compatibility with the aliphatic monohydric alcohols of No. 10; for example, ketones or keto alcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; diethyl glycol and triglycol Oxyethylene or oxypropylene addition polymers such as ethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycol, and polypropylene glycol; ethylene glycol, propylene glycol, trimethylene glycol, butylene glycol, 1,2,6- Alkylene glycols having an alkylene group containing 2 to 6 carbon atoms, such as hexane alkylene glycol and hexylene glycol; thiodiglycol; glycerin; ethylene glycol monomethyi (Or ethyl) ether, diethylene glycol monomethyl (or ethyl) ether,
Lower alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl (or ethyl) ether; triethylene glycol dimethyl (or ethyl) ether, tetraethylene glycol dimethyl (or ethyl)
Lower dialkyl ethers of polyhydric alcohols such as ethers; sulfolane, N-methyl-2-pyrrolidone, 1,3-
Dimethyl-2 pimidazolidinone and the like.

The content of the water-soluble organic solvent is generally 1% to 49%, preferably 2% to 30% by weight based on the total weight of the ink.
% Range.

The above-mentioned medium can be used alone or as a mixture, but the most preferable liquid medium composition contains at least one or more water-soluble high-boiling organic solvents, for example, diethylene glycol, triethylene glycol, and polyhydric alcohols such as glycerin. Things.

As the dye constituting the ink of the present invention, a direct dye,
Acid dyes, food dyes, basic dyes, reactive dyes, disperse dyes, vat dyes, soluble architectural dyes, reactive disperse dyes, oil dyes, and various pigments, among which water-soluble dyes are particularly preferred in terms of ink performance Things.

The content of these dyes is determined depending on the type of the liquid medium component, the characteristics required for the ink, and the like, but is generally about 0.2 to 20% by weight, preferably 0.5 to 10% by weight in the total amount of the ink.
%, More preferably 1-5%.

The main components of the ink of the present invention are as described above, but other various dispersants, surfactants, viscosity modifiers, surface tension modifiers, fluorescent brighteners, etc. are in a range that does not hinder the achievement of the object of the present invention. Can be added as needed.

For example, viscosity modifiers such as polyvinyl alcohol, celluloses, and water-soluble resins; various surfactants such as cation, anion or nonionic; surface tension regulators such as diethanolamine and triethanolamine; pH regulators with buffer solutions; Agents and the like.

Further, in order to prepare an ink used in an ink jet recording method of a type that charges the ink, a specific resistance adjuster such as inorganic salts such as lithium chloride, ammonium chloride, and sodium chloride is added.

Incidentally, the ink of the present invention is particularly suitable when applied to an ink jet recording method of a type in which the ink is ejected by a bubbling phenomenon of the ink due to thermal energy, the ejection becomes extremely stable, and the generation of satellite dots does not occur. There are features. However, in this case, the thermal physical property value (for example, specific heat, thermal expansion coefficient, thermal conductivity, etc.) may be adjusted.

Further, the ink of the present invention solves the problem of ink bleeding and the drying and penetrating properties of the recorded matter when recorded on plain paper or the like, and at the same time, improves the physical properties of the ink itself from the viewpoint of improving the matching with the ink jet head. It is desirable that the surface tension at 25 ° C. is adjusted to 30 to 68 dyne / cm and the viscosity is adjusted to 15 cP or less, preferably 10 cP or less, more preferably 5 cP or less.

(Examples) Next, the present invention will be described more specifically with reference to examples and comparative examples. In the following description, parts and% are based on weight unless otherwise specified.

Examples 1 to 5 After mixing the components shown in Table 1 below and stirring for 5 hours, the pH was adjusted to 7.5 with a 0.1% aqueous solution of sodium hydroxide, and a membrane filter having a pore size of 0.22 μm (trade name: Fluoro) Pressure filtration was performed using a pore filter (manufactured by Sumitomo Electric Industries, Ltd.) to obtain Inks A to E of the present invention.

Next, using the obtained inks A to E, as an ink jet recording apparatus, an ink jet printer BJ-130 using a heating element as an ink ejection energy source.
Using commercially available copy paper and bond paper (trade name: manufactured by Canon Inc.), the obtained recorded matter was evaluated for fixability and bleeding rate. At the same time, the clogging property at the time of reprinting after the printing was temporarily stopped, the clogging recovery property at the time of printing after the printing was stopped for a long time, the frequency response, and the storage stability of the ink were also evaluated. Table 3 shows the results. The evaluation was usually performed at 25 ° C. and 60% RH.

Comparative Examples 1 to 7 Inks F to L of Comparative Examples 1 to 7 were obtained in the same manner as in Examples 1 to 5 using the components shown in Table 2 below, and various evaluations were performed in the same manner as in the Examples. Was. Table 3 shows the results.

* 1 Fixability evaluation 10 seconds after printing on commercial copy paper and bond paper
After 30 seconds, the printed part is filtered with a filter paper (trade name: No.5C, Toyo Roshi Kaisha, Ltd.)
Manufactured) and evaluated as follows.

◎: No blurring in 10 seconds ○: Small blurring in 10 seconds △: Small blurring in 30 seconds ×: Large blurring in 30 seconds * 2 Occurrence rate of bleeding After 300 dots were printed so as to be discontinuous, the sample was left for 1 hour or more, and then the number of dots which caused blurring was counted under a microscope. The ratio to the total number of dots was expressed in% and evaluated as follows.

○: 10% or less △: 11 to 30% ×: 31% or more * 3 Temporary clogging Temporary clogging refers to clogging during reprinting after printing is temporarily stopped. After filling and printing alphanumeric characters continuously for 10 minutes, stop printing, leave for 10 minutes without cap etc.,
When alphanumeric characters were printed again, evaluation was made based on the presence / absence of defective portions such as blurred or missing characters.

○: No defective part from the first character △: Part of the first character is blurred or missing ×: The first character cannot be printed at all * 4 Long-term clogging recovery property When the printer is filled with the prescribed ink and prints alphanumeric characters continuously for 10 minutes, printing is stopped, and the printer is left without caps for 7 days. A clogging recovery operation was performed, and it was determined how many times the number of operations allowed normal printing without defective portions such as blurred or missing characters.

○: Normal printing is possible by 1 to 5 recovery operations △: Normal printing is possible by 6 to 10 recovery operations ×: Normal printing is possible by 11 or more recovery operations * 5 Frequency response The printed state of the printed material thus obtained, that is, the state of blurring or white spots, and the state of defective landing points such as splashes and skeins were visually observed and evaluated.

◎: The state of the ink following the frequency is good,
No blurring, white spots, or landing point defects were found in the solid printing character printing.

…: The ink follow-up state with respect to the frequency is almost good, and no fuzziness, white spots, and defective landing points are found in character printing, but slight fuzziness is seen in solid printing.

Δ: No blurring or white spots are observed in character printing, but some landing point defects are observed. In solid printing, blurring and white spots are observed about 1/3 of the entire solid printing.

C: Many blurs and white spots were observed in solid printing, and many blurs and landing point defects were observed in character printing.

* 6 Storage stability Put 100 cc of each ink into a heat-resistant glass bottle, seal it, store it in a high-temperature bath at 60 ° C for 3 months, then mount it on the recording device and print it on 100 continuous slip sheets. Was evaluated.

…: No abnormality ×: Non-discharge, disorder of printing or discoloration occur (Effect) As described above, according to the ink of the present invention, copy paper, report paper, and paper generally used in offices and the like are used.
It is possible to record on a plain paper such as a notebook and a stationery without bleeding and with high quality and good permeability.

Further, according to the present invention, it is possible to obtain an ink that is highly safe even when used in an office or at home.

Further, according to the ink of the present invention, it is possible to perform highly reliable recording without causing clogging in the nozzles of the inkjet head. Particularly, in recording of a type in which ink is ejected by a bubbling phenomenon of ink due to thermal energy, The responsiveness to frequency is much better.

Claims (1)

(57) [Claims] 1. A composition comprising a dye and a liquid medium,
At least 50-95% by weight of water and 0.001%
An ink-jet ink containing from about 4% by weight to an aliphatic monohydric alcohol having 9 or 10 carbon atoms.