JPH0742429B2 - Inkjet recording method - 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 jet recording method for performing recording on paper and various cloths generally used at home at high speed with low fixing property and excellent printing quality.

[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 requirements, 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 researches up to now, among the above-mentioned required performances, the most strongly required performances at present are (1) no bleeding on a recording material having exposed fibers, and a good fixing property. It is excellent, (2) compatible with high-speed recording, and good in frequency response.

First of all, regarding bleeding and fixability of the recording material with exposed fibers, especially when printing on ordinary plain paper such as copy paper, report paper, bond paper, continuous slip paper, etc. as the recording material. The problem is that the ink bleeds along the fibers of the paper and the fixability is insufficient due to the effect of the sizing agent contained in the plain paper.

Therefore, for the purpose of improving the bleeding and the fixing property, a method of recording using an ink whose pH is made strongly alkaline (JP-A-56-
57862 report), a method of recording using an ink to which a large amount of surfactant is added (JP-A-55-29546), and a method of recording a liquid as a liquid by heating solid ink at room temperature (JP-A-55-29546). 58-108271), etc. have already been tried. But,
The method of recording by making the pH of the ink strongly alkaline is dangerous when the ink is touched by hand, and the paper with a certain size may not have good bleeding and fixability. There are drawbacks such as. In addition, when a large amount of surfactant is added, bleeding may occur very much depending on the paper, or the ink may not be ejected because it recedes from the orifice surface depending on the conditions of the printer head. There are problems such as the entire surface getting wet and ink is not ejected. Furthermore, in the method of recording a liquid by heating solid ink at room temperature, bleeding,
There is some effect on the fixability of printing,
When a printer is designed, a device for supplying ink while melting it and a heating device in the printer head are required, which causes a problem that the printer becomes large and the cost is high.

Regarding the second problem, which is the improvement of the frequency response corresponding to high-speed recording, most of the studies are conducted from the viewpoint of the mechanical structure such as the head configuration, and the improvement of the ejection response frequency by ink is not so much studied. The reality is that it has not been done.

Generally, the frequency response is improved as the viscosity of the ink is decreased, however, the ejection stability is decreased accordingly. Therefore, it is difficult to develop an ink that improves the frequency response while maintaining the ejection stability. In particular, the on-demand type ink jet method has a problem that the frequency response and the ejection stability are poor under the driving condition of the frequency of 1 KHz or more, and this tendency becomes more remarkable when the driving frequency becomes 2 KHz and 4 KHz. This is a particularly serious problem in the ink jet method using a piezoelectric element or thermal energy.

Therefore, the main object of the present invention is not only the designated paper specially adjusted for ink jet, but also the copy paper, the report paper, the bond paper, the continuous slip paper, etc. on which the fibers are exposed on the recording surface and which are sized. Fixing speed is fast even on ordinary plain paper, and printing with less bleeding can be obtained.
An object of the present invention is to provide an ink jet recording method using an ink for ink jet which is safe and has excellent operability of ink.

Another object of the present invention is to provide an ink jet recording method that uses an ink having a good frequency response even if the driving frequency is high, and has a high printing speed.

[Means for solving problems]

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

That is, the present invention is an ink-jet recording method for performing recording by adhering ink droplets to a recording material at a driving frequency of 1 KHz or more by an on-demand type inkjet method, wherein the recording material is a fiber on its recording surface. And a composition containing at least one of a dye, a liquid medium in which the dye is dissolved or dispersed, and a cyclic compound having a plurality of pyranose rings is applied as the ink. Is.

[Work]

Explaining the present invention in more detail, the present invention provides stable ink with the improvement of ink fixability and print quality on a recording material having fibers exposed on the recording surface, and speeding up of the printer. As a result of earnest research on various additives, particularly surfactants and various sugars, in order to improve the frequency response to be ejected, the addition of a cyclic compound having a plurality of pyranose rings into the ink is very effective. It was made by knowing that.

Examples of the cyclic compound having a plurality of pyranose rings according to the present invention include glucose, fructose, monosaccharides such as galactose, and disaccharides such as sucrose, maltose, and lactose, which are 1,4 and 1,6 linked to form a ring. Examples thereof include compounds formed, but are not limited to these substances. Among them, the particularly preferable substance is
Cyclodextrins in which 6 or more α-D-glucopyranose groups are α-1,4-bonded to form a cyclic compound are mentioned, and the effect is remarkable.

Among cyclodextrins, α-cyclodextrin in which 6 glucose molecules are bound to form a ring and γ-cyclodextrin in which 8 are bound, and further maltosyl cyclo bound to maltose for the purpose of improving solubility in the cyclodextrin. Dextrin etc. are good.

These cyclic compounds having a plurality of pyranose rings may be used alone or in combination of two or more,
Furthermore, it is also possible to use it together with other surfactants.

The reason why the addition of a cyclic compound having a plurality of pyranose rings, especially the addition of cyclodextrin and / or its derivative is excellent in terms of fixing property on a recording material and print quality and frequency response is not clear, but It is presumed that the reason is presumed to be because the structure is cyclic, and the dye matrix or a part thereof is incorporated into the ring to form an inclusion compound. By forming an inclusion compound, the affinity for substances that originally had little affinity with the recording material or the structural material of the nozzle is improved, and the fibers are exposed on the recording material, especially on the recording surface. In addition, the fixing property may be improved even on general plain paper that has been sized, and the ink responsiveness to the nozzles may be improved to improve the frequency response of the ink. Presumed. Furthermore, addition of a cyclic compound having multiple pyranose rings, unlike addition of various surfactants, causes almost no decrease in the surface tension of the ink and, on the contrary, may cause a slight increase in the surface tension. It seems that not only the fixing on the recording material is fast, but also the printing quality is excellent without blurring.

Further, the cyclic compound has a large molecular weight as compared with various monosaccharides and disaccharides such as glucose and sucrose, but has a small increase in viscosity when added to the ink.

Therefore, it is possible to improve the fixability, print quality, and frequency response without degrading each performance required for ink jet recording.

Basically, the content of the cyclic compound is preferably 1 or more in terms of molar ratio with the dye (cyclic compound / dye).
0.1-20% by weight, preferably 0.2-
15% by weight, more preferably 0.5 to 10% by weight.

When the content of the cyclic compound is less than 0.1% by weight, the effect on the fixing property, the printing quality, and the improvement of the frequency response is not remarkable, and when the content of the cyclic compound exceeds 20% by weight, It is not preferable as an ink for ink jet from the viewpoint of increase in viscosity of ink and clogging.

As other components constituting the ink used in the present invention, first, as dyes, direct dyes, acid dyes, basic dyes, food dyes, reactive dyes, disperse dyes, vat dyes, soluble vat dyes, reactive disperse dyes, Examples include oil-soluble dyes and various pigments, and among them, water-soluble dyes are particularly preferable in terms of 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 liquid medium for dissolving or dispersing the dye as described above in the present invention, any of the media used in the media of conventional general ink jet recording inks can be used,
Water and / or organic solvents are preferred, for example methyl alcohol, ethyl alcohol, n.
-Propyl alcohol, isopropyl alcohol, n-
Alkyl alcohols having 1 to 5 carbon atoms such as butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, isobutyl alcohol, n-pentanol; amides such as dimethylformamide and dimethylacetamide;
Ketones or keto alcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; polyalkylene glycols such as polyethylene glycol and polypropylene glycol; ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,2, Alkyl glycols such as 6-hexanetriol, thiodiglycol, hexylene glycol, and diethylene glycol whose alkylene group contains 2 to 6 carbon atoms; glycerin; ethylene glycol monomethyl (or ethyl) ether, diethylene glycol monomethyl (or ethyl) ether Monoethyl ethers of polyhydric alcohols, such as triethylene glycol monomethyl (or ethyl) ether; Call dimethyl (or ethyl) ether, tetraethylene glycol dimethyl (or ethyl) lower dialkyl ethers of polyhydric alcohols such as ether; Surufuoran, N- methyl-2
Examples include pyrrolidone and 1,3-dimethyl-2-imidazolidinone.

The above media can be used alone or as a mixture,
The most preferable medium composition comprises water and one or more organic solvents, and the solvent contains at least one water-soluble high-boiling point organic solvent, for example, a polyhydric alcohol such as diethylene glycol, propylene glycol or glycerin. .

Although the essential components of the ink used in the present invention are as described above, other conventionally known various dispersants, surfactants,
Viscosity modifiers, surface tension modifiers, optical brighteners 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.

As described above, the ink jet ink used in the present invention is required to have a property for stable ejection from the printer head, particularly, a property for stable ejection at a drive frequency of 1 KHz or more, which is physical property. Preferably has a viscosity at 25 ° C of 15 cP or less and a surface tension of 35 to 65 dyne.
/ cm, more preferably the viscosity is adjusted to a low viscosity type of 3 cp or less.

The ink used in the present invention obtained as described above has fibers exposed on the recording material, especially on the recording surface thereof, and further, sized copy paper, report paper, bond paper, continuous slip paper, etc. It was obtained as a result of earnest research on an ink suitable for fixing property and printing quality on plain paper generally used in, and is effective as an ink for various types of ink jet, and excellent recording can be performed. .

In addition, it can respond accurately to the drive frequency for high-speed recording, which is increasingly demanded performance of 1KHz, 2KHz, 4KHz, especially on-demand type system in general, especially using piezoelectric element and thermal energy. Even in the type of ink jet system, excellent recording can be performed for a long period of time.

〔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, first, α-cyclodextrin was dissolved in water, then the dye CI Food Black 2 was added and stirred for 1 hour, glycerin, ethylene glycol and ethylene glycol monophenyl ether were further added and stirred for 3 hours at 40 ° C. . Then, after adjusting the pH to 7.5 with a 0.1% aqueous solution of sodium hydroxide, it was 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 (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.
μm, heater size 30 × 150 μm, number of nozzles 24, drive voltage 24.5V, frequency 2KHz) are used to print on commercially available copy paper and bond paper, and the fixability and print quality of the obtained prints are evaluated. did. Ink physical properties and evaluation results are shown in Table 1.

Example 2 Among the above components, first α-cyclodextrin is dissolved in water, then the dye CI Acid Red 35 is added and stirred,
Further, glycerin and 1,3-dimethyl-2-imidazolidinone were 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 (B) of the present invention was obtained by pressure filtration with Sumitomo Electric Co., Ltd.).

Example 3 (adjustment of ink C) Among the above components, first γ-cyclodextrin is dissolved in water, then the dye CI Direct Blue 86 is added and stirred, and further diethylene glycol, ethylene glycol, ethylene glycol monophenyl ether is added to 40
The mixture was stirred at 0 ° C for 3 hours. Then 0.
After adjusting the pH to 7.5 with a 1% aqueous solution, a fluoropore filter with a pore size of 1μ (trade name; Sumitomo Electric Industries, Ltd.)
(Pressurizing) to obtain an ink jet ink (C) of the present invention.

Example 4 Of the above ingredients, maltosyl cyclodextrin is first dissolved in water, then CI CI Food Black 154 is added and stirred, and then ethylene glycol and N-methyl-2- are added.
Add pyrrolidone and nonionic surfactant at 40 ℃ for 3
Stir for hours. Then, after adjusting the pH to 7.5 with a 0.1% aqueous solution of sodium hydroxide, it was 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

Example 5 (Adjustment of Ink E) Among the above components, firstly α and γ-cyclodextrin were dissolved in water, then the dye CI Direct Yellow 86 was added and stirred, and then triethylene glycol, ethylene glycol, 1,3-dimethyl-2-imidazolidinone were added. The mixture was stirred at 40 ° C for 3 hours. Then, after adjusting the pH to 7.5 with a 0.1% aqueous solution of sodium hydroxide, it was 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 (E) was obtained.

Comparative Example 1 Of the components in Example 1, the components except α-cyclodextrin were stirred for 3 hours, and then adjusted to pH 7.5 with a 0.1% aqueous solution of sodium hydroxide in the same manner as in Example 1,
A comparative ink (F) was obtained by pressure filtration with a Fluoropore filter (trade name; manufactured by Sumitomo Electric Industries, Ltd.) having a pore size of 1 μm.

Comparative Example 2 Comparative ink (G) was obtained by treating the components in Example 2 except for α-cyclodextrin in the same manner as in Comparative Example 1.

Comparative Example 3 A comparative ink (H) was obtained by treating the components in Example 3 except for γ-cyclodextrin in the same manner as in Comparative Example 1.

Comparative Example 4 (Preparation of Ink I) Comparative Ink (I) was obtained by treating in exactly the same manner as in Example 1 except that saccharose was used instead of α-cyclodextrin in Example 1.

Comparative Example 5 In Comparative Example 1, the maltosyl cyclodextrin was removed, and 0.5 parts of a nonionic surfactant (Nitsusan Nonion P223 (trade name), manufactured by NOF CORPORATION) was added instead. The same process was performed to obtain a comparative ink (J).

The same recording as in Example 1 was performed for the inks (B to J) of Examples 2 to 5 and Comparative Examples 1 to 5. Ink physical properties and evaluation results are shown in Table 1.

* 1 Viscosity measurement Tokyo Keiki VISCONIC ELD * 2 Surface tension measurement Kyowa Kagaku Kiyowa CBVP SURFACE TENSIOMETER A-1 * 3 Fixability evaluation Print on commercially available copy paper and bond paper 10 After 30 seconds, after 30 seconds the printing paper (paper name: No.5C, Toyo Kagaku Sangyo Co., Ltd.)
Made).

(Evaluated under the environmental conditions of 25 ° C, 60% RH) ◎ ……… No blurring in 10 seconds ○ ……… Small blurring in 10 seconds △ ……… Small blurring in 30 seconds × ………… Scratching large in 30 seconds * 4 Evaluation of printing quality After printing on the above-mentioned copy paper and bond paper, the paper was left 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.

Examples 6 to 20 and Comparative Examples 6 to 20 Inks A to J obtained in Examples 1 to 5 and Comparative Examples 1 to 5 were used, and the following printers (i) and (b) were used, and the frequency range was 1 to 6 KHz. Set inside the area, perform solid printing on the area of 15 × 4 cm ² and charactor printing of 130 characters of Alphabet on commercially available copy paper, and check the ink followability and landing point accuracy of the obtained print, The frequency response was evaluated, and the evaluation results are shown in Table 2.

(Printer) A heating element is used as a source of ink ejection energy (heater size 30 × 150 μm ² ) and orifice size 40 × 50
Inkjet printer with 24 μm ² nozzles (driving voltage 24.5V).

(Printer) A piezo element is used as a pressure unit applied to ink, and a mechanical displacement is generated in the piezo element by an electric signal to eject ink. An ink jet printer (driving voltage) with eight nozzles with an orifice diameter of 50 μm and a flow path length of 40 mm.
60V).

* 5 Evaluation of frequency responsiveness The printed state of the obtained printed matter, that is, the state of blurring or white spots and the state of defective landing point such as splashing and twisting was visually observed and evaluated.

⊚: The ink follows the frequency well, and neither solid prints nor charactor prints are free from scratches, white spots, and defective landing points.

◯: The ink followability with respect to the frequency is almost good, and there is no blur, white spots, or defective landing point in charactor printing, but slight blur is observed in solid printing.

△: No blemishes or white spots were seen in the charactor print, but some defective landing points were seen. Also, in solid printing, blurring and white spots are seen in about 1/3 of the whole solid.

×: There are many scratches and white spots in solid printing, and many scratches and defective landing points are also seen in charactor printing.

[Effect]

As described above, according to the present invention, not only the designated paper specially adjusted for the ink jet, but the fibers are exposed on the recording surface, and the ordinary plain paper that is sized, for example, copy paper, Report paper, bond paper,
It is possible to obtain printing with a fast fixing speed even on continuous slip paper and the like, and with less bleeding, which is safe and has excellent ink operability.

Furthermore, since the frequency response of the ink is good, high-speed and stable recording with a high driving frequency is possible.

Claims (6)

[Claims] 1. An inkjet recording method for recording by recording ink droplets on a recording material at a drive frequency of 1 KHz or more by an on-demand type inkjet method, wherein the recording material is a fiber on a recording image. The inkjet recording method is characterized in that a composition containing at least one of a dye, a liquid medium in which the dye is dissolved or dispersed, and a cyclic compound having a plurality of pyranose rings is applied as the ink. . 2. The ink jet recording method according to claim 1, wherein the cyclic compound is cyclodextrin or a derivative thereof. 3. The ink jet recording method according to claim 1, wherein the ink jet method is a method using a piezoelectric element. 4. The ink jet recording method according to claim 1, wherein the ink jet method is a method using heat energy. 5. The method according to claim 1, wherein the content of the cyclic compound is in the range of 0.1 to 20% by weight based on the total weight of the ink.
Inkjet recording method according to the item. 6. The ink jet recording method according to claim 1, wherein the recording material is a sized paper.