JPH0721125B2 - Ink for ink jet and ink jet recording method using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is applicable to office paper such as copy paper, report paper, bond paper, and continuous slip paper as well as designated paper specially adjusted for ink jet. The present invention relates to an ink for ink jet, which performs recording with fast fixing property and excellent printing quality on paper and various cloths generally used at home, and an ink jet recording method using the ink.

[Conventional technology]

The ink jet recording method forms ink droplets by various ink ejection methods, and makes a part or all of them adhere to a recording material such as paper, processed paper, plastic film, and woven cloth for recording. It is to be carried out, as the ink used in such an ink jet recording system, various dyes or pigments are known to be dissolved or dispersed in water or a liquid medium composed of water and a water-soluble organic solvent,
And is used.

Such ink is generally required to have the following performance including the relationship with the recording material.

(1) A recorded image of good quality without bleeding can be obtained.

(2) The fixing speed of the ink is high.

(3) Even if printing is interrupted for a while, the nozzles of the printer should not be clogged.

(4) The frequency response is good so that ink can be ejected according to the printing speed of the printer.

(5) The storage stability of the ink is high.

(6) High safety.

(7) Excellent durability of the printed matter such as water resistance and light resistance.

In order to satisfy some or all of the above performance, vigorous studies have been made from both sides of the ink and the device,
A considerable effect has been recognized depending on the required performance.

[Problems that the invention is trying to solve]

However, in spite of many studies to date, among the above-mentioned required performances, the most strongly required performance is that the recording material with exposed fibers has good water resistance and no bleeding. In addition, the fixing property is excellent.

This request becomes particularly remarkable when printing is performed on plain paper having a size such as copy paper, report paper, bond paper, and continuous slip paper as the recording material.

First, regarding the problem of improving bleeding and fixing property, Japanese Patent Laid-Open No.
56-57862 discloses a method of recording using an ink having a strongly alkaline pH, and JP-A-55-29546 discloses a method of recording using an ink to which a large amount of a surfactant is added. Further, Japanese Patent Laid-Open No. 58-108271 has already attempted a method of heating a solid ink at room temperature to form a liquid and recording the same.

However, the method of recording by making the pH of the ink strongly alkaline is dangerous when the ink is touched by hand, and also when the bleeding and fixing properties are not good for paper with a certain size. There are drawbacks such as

In addition, the method of adding a large amount of surfactant causes bleeding to occur very much depending on the paper, and depending on the conditions of the printer head, the ink may recede from the orifice surface and may not be ejected. There are problems such as the entire orifice surface getting wet and ink is not ejected.

Further, the method of recording a solid ink by heating it at a normal temperature to form a liquid has some effect on bleeding and print fixability. However, when designing a printer, a device or a printer that supplies ink while melting it is used. There is a problem in that the size of the printer becomes large due to the provision of a heating device in the head and the cost becomes high.

Next, regarding water resistance, many methods such as a method using an ink using an oily dye or a pigment and a method using a special paper to which a waterproofing agent is added have been proposed.

However, in these methods, problems of storage stability of ink and high cost of recording paper newly occur.

Therefore, an object of the present invention is not only specified paper specially adjusted for ink jet, but also ordinary plain paper such as copy paper, report paper, and bond that has fibers exposed on the recording surface and is further sized. It is an object of the present invention to provide an ink for ink jet, which is fast in fixing speed to paper, continuous slip paper, and the like, can be printed with little bleeding, is safe, and has excellent ink operability, and an ink jet recording method using the ink. .

Another object of the present invention is to provide an ink having excellent water resistance despite the use of a water-soluble dye, and to provide an ink jet recording method having good ejection stability.

[Means for solving problems]

 The above object is achieved by the present invention described below.

That is, according to the present invention, firstly, the solubility in water (20 ° C) is 1
% Water-soluble dye and an aqueous liquid medium for dissolving the dye, monensin, deoxycholic acid, 1,1,6,
An ink jet ink characterized by containing a compound of 6-tetraphenyl-2,4-hexadiyne-1,6-diol or 2,5-diphenylhydroquinone, and secondly, an ink jet method In the ink jet recording method for recording the ink droplets formed by adhering to the recording material, the recording material has fibers exposed on its recording surface, and has a solubility in water (20 ° C.) as the ink. A water-soluble dye of 1% or more, an aqueous liquid medium for dissolving the dye, monensin, deoxycholic acid, 1,1,6,6-tetraphenyl-2,4-hexadiyne-1,6-diol, Alternatively, the ink jet recording method is characterized in that a composition containing any compound of 2,5-diphenylhydroquinone is applied.

[Work]

The present invention is a finding obtained as a result of earnest research on a liquid medium composition in which water resistance and fixing property of an ink and a printing quality are good on a recording material having fibers exposed on a recording surface.

The compound characterizing the present invention is a compound having an inclusion ability to take in another substance into its pores, and more specifically, it is called a host molecule having a pore and clathrating another substance. is there.

The present invention is characterized by containing a host molecule having an inclusion ability, and the guest molecule corresponds to the dye matrix in the ink constituent or a part thereof.

By using an ink containing a compound having a three-dimensional structure having pores inside, which is formed by combining atoms or molecules as described above, water resistance and fixability on a recording material,
The reason why the print quality is excellent is not yet clear.

Probably, the dye matrix or a part of the dye matrix is incorporated into the pores to form an inclusion compound, which has a higher affinity for the recording material, particularly for sized ordinary plain paper, than for the dye alone, and fixing It is considered that the properties and water resistance are improved.

Also, the inclusion of these compounds, unlike the addition of various surfactants, does not cause a significant decrease in the surface tension of the ink,
No adverse effect on ejection stability is observed. Further, it is presumed that due to the formation of the clathrate compound, the dye molecules apparently become large and the fluidity is lowered, and there is no bleeding and recording with excellent print quality is obtained.

According to the study by the present inventors, in order to obtain good print quality without bleeding, the size of the host compound contained is important from the viewpoint of the fluidity of the clathrate compound containing a dye, and specifically, The molecular weight of the host compound must be 100 or more.

Therefore, the ink containing a host compound such as urea or thiourea having a molecular weight of less than 100, which is said to have clathrate ability, has an insufficient effect of preventing bleeding and obtains good print quality recording. It's difficult.

In the present invention, as such a compound, particularly monensin, deoxycholic acid, 1,1,6,6-tetraphenyl-
2,4-hexadiyne-1,6-diol or 2,5-diphenylhydroquinone can be preferably used.

The content of the compound is 0.1 to 20 with respect to the total weight of the ink.
% By weight, preferably 0.2-15% by weight, more preferably 0.5
Is in the range of up to 10% by weight.

When the content of the compound is less than 0.1% by weight, the effect on the improvement of fixing property, print quality and ejection stability is not remarkable, and when the content of the compound exceeds 20% by weight, the viscosity of the ink is It is not preferable as an ink for ink jet from the viewpoint of rising and clogging.

As other components constituting the ink of the present invention, first, as a pigment, a direct dye, an acid dye, a basic dye, an edible dye,
Water-soluble dyes such as reactive dyes, vat dyes, and soluble vat dyes can be mentioned.

As a criterion of "water solubility", in the case of the ink of the present invention, if the solubility at least at 20 ° C is 1% or more, there is no problem in the ink performance.

The content of these dyes is determined depending on the type of liquid medium component, properties required for the ink, etc., but generally 0.2 to 20% by weight, preferably 0.5 to 10% by weight, based on the total weight of the ink. It is more preferably in the range of 1 to 5% by weight.

As the aqueous liquid medium for dissolving the dye as described above in the present invention, any of the media used in the media of conventional general ink jet recording ink can be used, for example, water and / or an organic solvent is preferable, and Examples of the solvent include alkyl alcohols having 1 to 5 carbon atoms such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, isobutyl alcohol and n-pentanol, Amides such as dimethylformamide and dimethylacetamide; Ketones and keto alcohols such as acetone and diacetone alcohol; Ethers such as tetrahydrofuran and dioxane; Polyalkylenes such as polyethylene glycol and polypropylene glycol Recalls; ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol and other alkylene groups containing 2 to 6 carbon atoms. Kinds; Glycerin; Ethylene glycol monomethyl (or ethyl) ether, Diethylene glycol monomethyl (or ethyl)
Lower monoalkyl ethers of polyhydric alcohols such as ether and triethylene glycol monomethyl (or ethyl) ether; lower dialkyl of polyhydric alcohols such as triethylene glycol dimethyl (or ethyl) ether and tetraethylene glycol dimethyl (or ethyl) ether Ethers: sulfolane, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone and the like can be mentioned.

The essential components of the ink of the present invention are as described above, but other conventionally known various dispersants, surfactants, viscosity modifiers,
A surface tension adjusting agent, a fluorescent whitening agent and the like can be added as necessary.

For example, viscosity adjusting agents such as polyvinyl alcohol, celluloses and water-soluble resins; surface tension adjusting agents such as cationic, anionic or nonionic surfactants, diethanolamine and triethanolamines; pH by buffer solution
Examples thereof include regulators and fungicides.

Further, in order to prepare the ink used in the ink jet recording method of charging the ink, a specific resistance adjusting agent such as lithium chloride, ammonium chloride or an inorganic salt of sodium chloride is added. When applied to an ink jet method in which ink is ejected by the action of thermal energy, thermal physical property values (for example, specific heat, coefficient of thermal expansion, thermal conductivity, etc.) may be adjusted.

In order for the ink jet ink of the present invention as described above to be stably ejected from the printer head, the physical properties are preferably a viscosity at 25 ° C. of 15 cP or less and a surface tension of 35 to 65.
It is desirable that the viscosity is adjusted to a low viscosity type of 3 cP or less, more preferably dyne / cm.

The ink of the present invention and the ink used in the present invention obtained as described above have fibers exposed on the recording material, especially on the recording surface, and further, sized copy paper, report paper, bond paper, continuous slip paper, etc. It is excellent in water resistance, fixability and printing quality on office papers and plain papers generally used at home, and is effective as an ink for various types of ink jet, and excellent recording can be performed.

〔Example〕

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples. In the text, all parts and% are based on weight.

Example 1 Of the above components, monensin was first dissolved in water, then the dye CI Food Black 2 was added, and the mixture was stirred for 1 hour, glycerin, ethylene glycol and ethylene glycol monophenyl ether were further added, and the mixture was stirred at 40 ° C. for 3 hours.
Thereafter, the pH was adjusted to 7.5 with a 0.1% aqueous solution of sodium hydroxide, and the mixture was pressure-filtered with a Fluoropore filter (trade name; manufactured by Sumitomo Electric Co., Ltd.) having a pore size of 1 μm to perform the ink jet ink of the invention. (A) was obtained.

Next, using this ink, an ink jet printer (Olyphis size 40 × 50) that uses a heating element as an ink ejection energy source as an ink jet recording device is used.
.mu.m, heater size 30.times.150 .mu.m, number of nozzles 24, drive voltage 24.5V, frequency 2KHz) were used to print on commercially available copy paper and bond paper to evaluate ejection stability. Further, the fixability, print quality and water resistance of the obtained prints were evaluated. Ink physical properties and evaluation results are shown in Table 1.

Example 2 Of the above components, first deoxycholic acid was dissolved in water adjusted to pH 10 with a 0.1% sodium hydroxide aqueous solution, then the dye CI Acid Red 35 was added and stirred, and then glycerin and N-methyl-2-pyrrolidone were added. The mixture was stirred at 40 ° C for 3 hours. After that, pressure filtration was performed with a fluoropore filter (trade name; manufactured by Sumitomo Electric Industries, Ltd.) having a pore size of 1 μm to obtain the ink (B) for ink jet of the present invention.

Example 3 In the above components, 1,1,6,6-tetraphenyl-2,4-hexadiyne-1,6-diol was first dissolved in water, and then the dye
CI Direct Blue 86 was added and stirred, diethylene glycol and 1,3-dimethyl-2-imidazolidinone were further added, and the mixture was stirred at 40 ° C. for 3 hours. After that, adjust the pH to 7.5 with a 0.1% aqueous solution of sodium hydroxide, and then use a fluoropore filter with a pore size of 1μ (trade name;
The ink for ink jet (C) of the present invention was obtained by pressure filtration with Sumitomo Electric Co., Ltd.).

Example 4 Of the above components, first, 2,5-diphenylhydroquinone is dissolved in water, then the dye CI Direct Black 154 is added and stirred, and diethylene glycol, ethylene glycol, and a nonionic surfactant are added, and the mixture is mixed at 40 ° C. for 3 days.
Stir for hours. Then, after adjusting the pH to 7.5 with a 0.1% aqueous solution of sodium hydroxide, it is filtered with a fluoropore filter (trade name; manufactured by Sumitomo Electric Co., Ltd.) having a pore size of 1 μm to apply pressure to the ink jet of the present invention. Ink (D)
Got

Comparative Example 1 Of the components in Example 1, 3 components except monensin were used.
After stirring for 0.1 hour, 0.1% sodium hydroxide was added as in Example 1.
% Aqueous solution to adjust the pH to 7.5, and then a fluoropore filter with a pore size of 1μ (trade name; Sumitomo Electric Industries, Ltd.)
(Commercial product) to obtain a comparative ink (E).

Comparative Example 2 Among the components in Example 2, the components excluding deoxycholic acid were treated in the same manner as in Comparative Example 1 to obtain a comparative ink (F).

Comparative Example 3 Comparative Ink (G) was processed in the same manner as in Example 1 except that urea was used instead of monensin in Example 1.
Got

Comparative Example 4 In Example 4, except that 2,5-diphenylhydroquinone was removed, 0.4 part of a nonionic surfactant (Nitsusan Nonion P223 (trade name), manufactured by NOF CORPORATION) was added instead, and comparison was made. The same treatment as in Example 1 was carried out to obtain a comparative ink (H).

The same recording as in Example 1 was performed for the inks (B to H) of Examples 2 to 4 and Comparative Examples 1 to 4. Ink physical properties and evaluation results are shown in Table 1.

* 1 Viscosity measurement VISCONIC ELD (trade name) made by Tokyo Keiki * 2 Surface tension measurement Kyowa CBVP SURFACE TENSIOMETER A-1 (trade name) made by Kyowa Kagaku * 3 Fixability evaluation Commercially available copy paper Also, 10 seconds after printing on bond paper, 30 seconds after printing, the printing part is filtered (brand name: No. 5C, Toyo Kagaku Sangyo Co., Ltd.)
Made).

(Evaluated under environmental conditions of 25 ° C and 60% RH) ◎ …… No blurring in 10 seconds ○ …… Small blurring in 10 seconds △ …… Small blurring in 30 seconds × …… Large scraping in 30 seconds * 4 Print quality Evaluation After printing on the above-mentioned copy paper and bond paper, the paper was allowed to stand for 1 hour or more, and then bleeding at a dot level and edge sharpness were evaluated.

(Evaluated under the environmental conditions of 25 ° C and 60% RH) ◎ …… No bleeding and the edge is extremely sharp.

O: Some blurring is seen, but the edge of the dot is sharp.

△: Almost all dots are blurred and the edges of the dots are slightly blurred.

× …… Bleeds are seen in all dots, and the edges of dots are not clear.

* 5 Water resistance evaluation After printing on the above-mentioned copy paper, leave the printed sample for 1 day,
Then, it was immersed in water for 1 minute to evaluate the blurring of the image.

○: Almost no bleeding is seen.

△ …… Slight bleeding is seen.

×: Many blurs occur, making it difficult to read the image.

* 6 Discharge stability evaluation 1 × 10 ⁷ characters were printed on the above-mentioned copy paper, and the disorder of printing was evaluated.

○: No print distortion is observed.

△: The dots are slightly defective, but the characters are easy to read.

×: Many poor dot impact points were found, making it difficult to read the characters.

[Effect]

As described above, according to the present invention, not only the designated paper specially adjusted for the ink jet but also the ordinary plain paper, for example, copy paper, in which the fibers are exposed on the recording surface and further sized, Ink jet recording is also possible, which has good water resistance for report paper, bond paper, continuous slip paper, etc., has a high fixing speed, and can provide printing with less bleeding.

Further, according to the present invention, it is possible to perform ink jet recording which is safe and has excellent ejection stability and ink operability.

Claims (7)

[Claims] 1. A water-soluble dye having a solubility in water (20 ° C.) of 1% or more, and an aqueous liquid medium for dissolving the dye.
And monensin, deoxycholic acid, 1,1,6,6-tetraphenyl-2,4-hexadiyne-1,6-diol, or 2,
An inkjet ink comprising a compound of 5-diphenylhydroquinone. 2. The inkjet ink according to claim 1, wherein the content of the compound is in the range of 0.1 to 20% by weight based on the total weight of the ink. 3. The ink jet ink according to claim 1, wherein the ink has a viscosity at 25 ° C. of 15 cP or less and a surface tension in the range of 35 to 65 dyne / cm. 4. An ink jet recording method for recording by recording ink droplets formed by an ink jet method on a recording material, wherein the recording material has fibers exposed on its recording surface, and water is used as the ink. Water soluble dye having a solubility (20 ° C) of 1% or more with respect to water, an aqueous liquid medium for dissolving the dye, and monensin, deoxycholic acid, 1,1,6,6-tetraphenyl-2,4-hexadiyne An inkjet recording method comprising applying a composition containing a compound of either 1,6-diol or 2,5-diphenylhydroquinone. 5. The ink jet recording method according to claim 4, wherein the recording material is sized paper. 6. The content of the compound in the ink is 0.
The ink jet recording method according to claim (4), which is in the range of 1 to 20% by weight. 7. The ink jet recording method according to claim 4, wherein the ink has a viscosity at 25 ° C. of not more than 15 cP and a surface tension in the range of 35 to 65 dyne / cm.