JPS5813675A - Ink composition for ink jet recording and recording method - Google Patents

Abstract

PURPOSE:The titled composition, consisting of an aqueous solution containing a specific polymer of vinylpyrrolidone and a specific amount of water as a solvent without causing blots of ink dots jetted on a recording appare, and capable of giving excellent printed letters having a high grade and resolving power. CONSTITUTION:An ink composition consisting of an aqueous solution containing a polymer of a vinylpyrrolidone, preferably N-vinylpyrrolidone homopolymer or a copolymer with another monomer, e.g. ethylene, having a molecular weight >=40,000, and 50wt% or more water is used to fill a pressure chamber communicated with a nozzle. The wall of the pressure chamber is displaced inward by the action of an electromechanical converting means on application of electrical driving pulses to rapidly reduce the internal volume of the pressure chamber and jet the ink composition as ink droplets from the nozzle in the direction of a recording medium for recording. The composition has a viscosity of preferably 1.8-15cP at 30 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an in-ink composition for recording (Infusiera) and a recording method, which have excellent properties such as high quality and high resolution, with no bleeding of ink dots jetted onto recording paper. This invention relates to an inkjet recording ink composition capable of printing and a recording '75 method TL.

Traditionally, for inkjet recording ink,
It goes without saying that it is important to be able to print stably from the nozzle, but it has also been desired that excellent print recording with high quality and high resolution can be obtained in whichever inkjet recording method is used.

Inkjet recording 77 methods include pressure vibration type (including charge amount control method, electric field control method, binary control method,
Includes scattering angle control methods. ), electrostatic acceleration type, and on-demand pressure vacuum type are known.

Although the inkjet recording ink composition of the present invention can be applied to any of the above inkjet recording methods,
%, it can be suitably applied to on-demand type pressure bag type inkjet printing method.

Below, inkjet recording ff, r on demand! This will be explained using Eve's pressure bag type inkjet recording method. .

The on-demand Shocabarus type inkjet recording method fills a pressure chamber communicating with a nozzle with an ink composition, the pressure chamber being capable of deforming at least a portion of its wall by an electromechanical transducer. When the electric drive pulse is applied, the electromechanical transducer is actuated to displace the wall of the pressure chamber inward 73, rapidly reducing the internal volume of the pressure chamber, and reducing the pressure inside the pressure chamber. ejecting a portion of the amount of the ink composition as a single ink droplet from a nozzle in the direction of the recording medium; - restoring the volume of the pressure chamber after ejection of a single ink droplet per drive pulse; It consists of the process of restoring the initial ink equilibrium state and preparing for the next jetting. This method is described, for example, in U.S. Pat. No. 3,946,396, U.S. Pat.
Same issue! No. 4,144,537, ll! 4,162,5
No. 01, No. 14, 17, No. 363, No. 4, 17
Specification No. 6,361,! Opening and closing number 52-56414, same 5
No. 5-82175 and Japanese Patent Publication No. 53-10916.

However, as far as we have examined print samples from on-demand pressure cabling type inkjet recording using conventional jet ink, we have found that the characters on the recording paper smear significantly, and the characters that require high resolution, for example, It is difficult to print kanji characters, etc., and therefore there has been a demand for a new jet ink that can provide excellent print records with high quality and resolution.

Not only the on-demand inkjet F& method, but also the continuous inkjet I & Katana method, many of which use designated paper.

When comparing the prints made on designated paper and non-designated recording paper using various types of inkjet printers, it was found that compared to those printed on designated paper, the prints were jetted onto other recording papers. This is because ink dots tend to smudge and have poor character resolution.

A first object of the present invention is to provide an inkjet recording ink composition for printing with high resolution.

A second object of the present invention is to provide an inkjet ink composition that can print with high quality and high resolution on any recording paper, not just designated paper.

The third object of the present invention is essential for on-demand inkjet! Another object of the present invention is to provide an ink composition for a winkjet with a suitable viscosity.

The present inventors have made extensive studies for these purposes, and found that the main solvent of conventional on-demand inkjet ink compositions (hereinafter referred to as jet inks) is glycols. Use a jet ink that uses water as the main solvent, that is, at least 50 percent by weight of the ink is composed of water, and is a nonionic water-soluble polymer with an average molecular weight of 40,000. These objects have been achieved by a jet ink containing the above vinylpyrrolidone polymer.

A fourth object of the present invention is to provide an inkjet recording method that can achieve the above object of at to $3.

A fourth object of the present invention is to fill a pressure chamber communicating with a nozzle with an ink composition so that at least a portion of the wall of the pressure chamber can be deformed by electromechanical conversion means. When an electric drive pulse is applied, the pressure chamber is displaced inwardly by the operation of the tortoise-mechanical converting means, and the internal volume of the scissors pressure chamber is rapidly reduced, and the pressure chamber is ejecting an amount of the ink composition -S as -1 m ink droplets from a nozzle in the direction of the recording medium, and restoring the volume of the pressure chamber after ejecting m ink droplets in response to a - drive pulse; , an inkjet recording method for restoring the initial ink equilibrium state, wherein the ink composition comprises an aqueous solution containing a vinylpyrrolidone polymer having an average molecular weight of 40,000 or more and at least 50% water by weight. This is accomplished by an inkjet recording method.

The present invention will be explained in detail below. The present invention provides a jet ink containing at least 50% by weight of water,
The present invention is an inkjet recording ink composition characterized by containing a 7=ruvirolidone polymer having an average molecular weight of 40,000 or more. The first advantage of the jet ink made from the composition of the present invention is that high-quality, high-resolution print recording can be achieved.

Various methods can be considered for determining the resolution in inkjet recording, but the best method is to determine it based on the line width and its variation when Ka1 characters are printed on the same recording paper. If the ink dots ejected on the recording paper bleed randomly, it will cause poor printing resolution.Even if a thin line can be formed in some areas, the line width will be thicker in the area where the random KIC bleeds, so the result will be The characters are of low quality and low resolution. With the jet ink of the present invention, such 5Z random trap bleeds are extremely reduced, and high-resolution printing can be achieved.

The second advantage of the jet ink of the present invention is that the print quality does not change significantly depending on the recording paper. It is to be. In general, plain paper can be roughly divided into two types: those that absorb ink and those that do not. If the former is referred to herein as absorbent paper and the latter as t-non-absorbent paper, it is inevitable that absorbent paper has a wider line width than non-absorbent paper. However, with conventional jet inks that mainly contain glycol, not only the line width becomes wider than that of absorbent paper, but also random bleeding occurs in the characters, reducing the resolution and resulting in low-quality characters. -force,
Jet inks containing more than 501 cents of water, but containing certain polyethylene glycols, produce characters of satisfactory quality on absorbent paper, but on non-absorbent paper. However, the jet ink caused significant bleeding in some areas and gave low-quality characters.

The jet ink of the present invention does not change the quality of characters depending on the recording paper, unlike the jet inks described above, and can provide high-quality printing on any recording paper.

It has been known that various water-soluble polymers can be used in jet inks whose main component is water, but
The average molecular weight of the ink composition of the present invention is 40.
The superior characteristics found in jet inks containing polymers of vinyl pyrrolidone of 1,000 or more are undeniable advantages over jet inks containing water-soluble polymers among them.

Other jet inks containing water-soluble polymers are inferior in the following points.

As a first example, French Patent No. 1,480,068 and Japanese Unexamined Patent Application Publication No. 1983-1980 disclose that polyethyleneimine is added to jet ink to improve the water resistance of printed matter.
As stated in Japanese Patent No. 120676, polyethyleneimine easily reacts with the azo group (-N=N-) of azo dyes often used in jet inks to form condensates and precipitates, destroying the dye. . Also, from the point of view of printing quality, lf!
The fK is not excellent, and the print quality on various types of recording paper is poor, that is, the line width is wide and the random bleeding of ink is large.

As a second example, carboxymethyl cellulose (hereinafter referred to as CM C), which is a cellulose-based water-soluble polymer, is used.
An attempt to suppress the ink from bleeding in the lateral direction on the paper surface using the method is described in Japanese Patent Application Laid-Open No. 55-80477. However, since CMC is an ionic water-soluble polymer, adding dyes that can take an ionic structure, such as direct dyes often used in jet inks, has the effect of increasing viscosity.
Therefore, water-soluble polymers used in ink compositions for on-demand inkjet recording must be nonionic.

In this regard, the third advantage of the jet ink of the present invention is that it is an inkjet ink composition having an appropriate viscosity that provides jetting stability in on-demand pressure cabling type inkjet. , appropriate viscous redness is 1.8 ape ~ l 5 c at 30°C.
ps, preferably 2.0 cps to 14 cps, more preferably 3.0 cps. Ocps ~10eps.

Furthermore, as a third example, polyvinyl alcohol, which is a nonionic water-soluble polymer, does not improve printing quality (that is, high-resolution jet ink cannot be produced).
However, the head is easily clogged and the jetting stability is extremely poor.

W! Examples of J4 include polyacrylic acid and sodium alginate, which are ionic water-soluble polymers and are unsuitable for the jet ink of the present invention.

As a fifth example, polyacrylic acid ester, which is often used in printing inks, etc., does not dissolve in water and requires a special dissolution technique, and is therefore unsuitable for the present invention.

As a sixth example, the addition of N-vinylpyrrolidone oligomer to jet ink for jetting stability is disclosed in Japanese Patent Publication No. 102407/1983, but this disclosure is not disclosed. , is an oligomer and has a molecular weight of 270 to 400, and the average molecular weight of the present invention is 40.0.
Polymers of vinylpyrrolidones with a number of 00 or more are 14.

By the way, the use of polyvinylpyrrolidone in JP-A-55-48266 and JP-A-55-12
No. 06 ``''I'l/r Publication Properties are disclosed, but the polyvinylpyrrolidone used in the jet inks of these publications has a molecular weight of 2,000 to 0.000.

This is different from the polyvinylpyrrolidone used in the present invention, and the required physical properties also vary depending on the company used for jet ink.

Further, the present invention preferably includes an electrolyte for the jet ink, as described below.
The configuration is 14 in this respect as well as those described in the respective publications of No. 1, No. 55-48266, and No. 55-120677. That is, the jet ink of the present invention contains an acetate, preferably potassium acetate or sodium acetate, as a stabilizer. As the base, an inorganic base such as potassium carbonate or sodium carbonate can be used, and an organic base can also be used to improve the physical properties of the jet ink. Furthermore, an inorganic base and an organic base can also be used together. Desirable cold bases include various amines, particularly aliphatic amines, and even more preferably non-amines. Preferred examples include triethanolamine and permethylated tetraethylenepentamine.

Among the vinylpyrrolidone polymers of the present invention having an average molecular weight of 40,000 or more, one end of the main chain of polyvinylpyrrolidone is substituted with an alkyne group or a substituted alkyl group,
Also included are polyvinylpyrrolidone derivatives in which the other side is substituted with a halogen atom and vinylpyrrolidone collar conductors in which the pyrrolidone nucleus is substituted with an alkyl group or the like.

However, in the jet ink of the present invention, a ms polymer of N-vinylpyrrolidone or a copolymer of other monomers is preferred. Any other monomer can be used as long as it is copolymerizable with N-vinylpyrrolidone, including ethylene, propylene,
Specific examples include vinyl chloride, acrylic acid, methyl acrylate, styrene, vinyl acetate, and acrylonitrile. However, in the case of a copolymer, the purpose of the present invention may not be achieved if the content ratio of the middle monomer increases, so the content ratio F13 of the Tsukuda monomer
09! The following is preferable.

In the present invention, by using a polyvinylpyrrolidone derivative, the solubility in water may be lowered, but
In that case, if necessary, a surfactant or a suitable dispersion method such as lattice dispersion may be used.

The dye used in the present invention is preferably a water-soluble direct dye, for example, one that has at least a free amino group in the molecule (in the general term of organic chemistry) (the original properties of the amino group are not inhibited by intramolecular hydrogen bonds, etc.). ) or amino group precursor 3
Preferred are direct dyes having orchid or higher.

Examples of dyes are shown below, but the present invention is not limited to these examples.

H (However, M represents any element of Na, H, or H.

same as below. ) H (represents all real numbers greater than or equal to nFiO and less than or equal to 2.) H2 \ H2 H2 H (m is a real number greater than or equal to 0 and less than or equal to 2) The free amine group or amino group precursor has only 2111 or more) (a mixture of dyes may be used). For example, if you want to obtain a neutral black color, mixing a black dye with a strong bluish tinge and a black dye with a strong reddish tinge will produce a neutral black tone, so this is used when you need to improve these physical properties. be able to.

The jet ink of the present invention will be explained in detail below.

Water-glycols mixed solution 11H for dissolving dyes
In t, glycols include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol (those with an average molecular weight of 1000 or less are u, !L''), and glycols in which one of the hydroxyl groups of these glycols has been etherified. For example, butyl calpitol, diethylene glycol monomethyl ether, diethylene/'J-col monoethyl ether, ethoxyethanol, etc., with a molecular weight of 1111°, and the average molecular weight of hFi with the molecular weight of glycols here are too
It is preferably 800 or less. Furthermore, in the present invention, the glycols referred to as "water-glycol mixed solvent" may be used in combination of at least one and up to 5 of the above, preferably at least 1 and up to 3. Good combination.

Stabilizers and minerals are used to enhance the storage stability of the jet ink of the present invention, and prevent isomorphic substances from precipitating in the jet ink during storage or non-operation, preventing nozzle clogging, and Stabilizes jetting during operation (prevents the formation of similar or foreign objects on the inkjet nozzle head surface.

) is a thing.

Preferred stabilizers are acetates, among which potassium acetate or sodium acetate are suitable. Content? :to
, otl amount percent (hereinafter abbreviated as wt) or more and 5wt1G or less, more preferably Fio,
05 wt arrogance is less than 1,4wt.

It is known that the surface T# tension of jet ink is a physical property value that is important due to the viscosity, etc., but on-demand! Jet ink of Eve's pressure couple slippers! ! Surface tension ore 40-60
dyn "all" is preferred.

The preservative in shet ink is used to prevent the occurrence and growth of bacteria and mold, or to reduce Fi.

Bacteria and the like accumulate in the nozzle and cause clogging, and in severe cases, they can significantly deteriorate the physical properties of the ink. Various water-soluble preservatives can be added to the jet ink of the present invention.
Preferred examples include dioxin, Batilard 35 commercially available from Hoechst, sodium dehydroacetate, Bestside commercially available from Dainippon Ink, potassium sorbate, and Prebentol CMK-Na commercially available from Bayer. and Movin B. The amount of preservative added is 0.01 to 4.0% by weight, preferably 0.02 to 3.5% by weight.

Furthermore, various chelating agents are added for the purpose of masking metal and gold ions in the ink composition.

Typical examples include gluconium sodium, ethylenediaminetetraacetic acid (EDTA), N: sodium salt,
Examples include king sodium salt, doyen sodium salt, and sodium diethylenetriaminobenmeacetic acid. The amount added is 0.02 to 2. Owt fluent, preferably O,O
S~1. Q: I'm sorry.

Furthermore, a fluorine-based surfactant, polyoxyalkylene, or the like may be added to improve the physical properties of the ink, if necessary.

Examples of actual implementations of the present invention are described below, but the implementation aspects of the invention are not limited to the following examples. The inkjet printer [manufactured by Konishi Roku Photo Industry ■] used in the following actual winding example is a pressure caballus type with an on-demand tab that has multiple nozzles, and the inkjet head photoelectric nozzle O diameter is approximately 4000μ. be. In addition, for analysis of dots and lines, we used Area Duck, a dot analysis device manufactured by Konishiroku Photo Industry ■.

Do all the jet ink (1) as in Dormitory Scary Example - Rii)! l
11! Shita.

In addition, the dye is a commercially available one using the usual salting out method.
It was desalted as much as possible, finally washed with ethanol τ, and dried.

The above mixture was repeatedly filtered and finally filtered through a filter with a pore size of 1 pm. Viscosity 1 [ti4.5e
pm (30°C).

For comparison, polyvinylpyrrolidone-
90.5g & polyethylene griffle 600.200
Comparative jet ink (1) was prepared in the same manner except that ink was replaced with g. The viscosity was 4.2 cps (30°C).
″′ Printing was performed on different types of recording paper as shown below using an inkjet head having a nozzle O diameter of about 4000μ.

(1) Inkjet cough paper (manufactured by Mitsubishi Paper Mills, basis weight: 62 g/n/d) Non-absorbent regular paper (hardly absorbs ink), basis weight: 64 g/d Necessary as it hardly absorbs ink Dry with heat as required.

The line width of the straight portion when recorded on these was compared between the jet ink of the present invention and the jet ink of the comparative example.

The jet ink (1) of the present invention has a print quality of 160 = 180 pm for one sheet of paper and 130 to 150 pm for paper (B) K, and print quality for any paper (for example, kanji characters). It was extremely excellent.

On the other hand, the comparatively soft JE'/Tink (1) is 250 to 35 G #m to paper (integrated paper), and paper (integrated).
B) K vs. Shiso 200-500JI! l, for each paper a bleed is made in the direction of the paper fibers,
In addition, the line width was wide, and the printing quality was insufficient.

Actual example-2 The following jet ink (2) was prepared.

The mixture was completely filtered again and finally filtered through a JPM pore size filter. The viscosity is 3.8 cps (
30°C).

For comparison, polyvinylpyrrolidone-
60.5g and ethylene glycol 370gt) Comparative jet ink (2
) +t- prepared. The viscosity was 5.2 cpg (30°C).

These inks t-*Beno of Example-1<-(A), (
II), the line width values of the straight portions were as follows. (Nozzle diameter approximately 4000 sd) The jet ink (2) of the present invention is 200 to 30071 nl with respect to the paper (integrated paper),
It was 170-175 am for paper (B) K.

On the other hand, the comparison jet ink (2) is similar to paper (1).
250-375 sgl for paper (B
) was 200 to 400 μm.

As can be seen from these line widths, the jet ink of the present invention was able to print with high resolution on any recording paper compared to the comparative jet ink K.

Actual case-3 Jet ink (3) was produced as follows.

The above mixture was subjected to repeated furnace treatment and filtered through a final trap with a pore size of 1 μm. The viscosity is 4.2 eps (3
0°C).

First, a comparative jet ink (3) was prepared by excluding polyvinylpyrrolidone-90 from the above components, changing the amount of ethylene glycol from 150g to 12011c, and changing the amount of polyethylene glycol from 150g to 300gK, and the viscosity was 6. .3epm (30°C).

When printed on the same trap papers (A) and (B) as in Example 1, the line width values of the straight portions were as follows. .

Jet-in of the present invention! (3) is 220 to 380 μm for pH and 250 to 300 am for paper (B).

- 10,000, jet ink (3) on the north wall is paper (4)
230-410jnx for paper (B)
It was 200-400 am with respect to K.

For absorbent paper (■), both inks had satisfactory print quality, whereas for non-absorbent paper (B) and K, the jet ink of the present invention (3) had satisfactory print quality. Comparative jet ink (3) had a lot of bleeding in the direction of the fibers, resulting in insufficient print quality.

Actual case-4 The following jet ink (4) tIII was made.

The above mixture was filtered and finally passed through a Filjm pore size filter. Viscosity is 6.0 cps
(30°C).

For comparison, a comparative jet 1 ink (4) was prepared in which among the above components, poly-nylpyrrolidone was replaced by -90'K and polyvinylpyrrolidone was replaced by -15K (average molecular weight 10,000). The viscosity was 2.5 cps (30°C).

When the ejection stability of these inks was compared, jet ink (4) was ejected stably, whereas soft jet ink (4) was extremely unstable.

4 In addition, when printing on paper (4), @) (described above), compared to jet ink (4), as in Examples 1 to 3, comparative jet ink (4) has a lower randomness on paper. The bleeding is extremely large, and poly-nylpyrrolidone K
-15 was unsatisfactory in terms of print quality.

Patent applicant Roku Konishi Photo Industry Co., Ltd., patent attorney
Saka omiis (1 person)

Claims (1)

Claims: (1) An inkjet recording ink composition comprising an aqueous solution/liquid containing a vinylpyrrolidone polymer having an average molecular weight of 40,000 or more and at least 50% water by weight. (The ink composition for inkjet recording according to claim 1, characterized in that the viscosity at 2130° C. is 1.8 to L5 centivoise. (3) The pressure chamber communicating with the nozzle is the pressure chamber is configured such that at least a portion of its wall can be deformed by electromechanical transducing means;
When an electrical drive pulse is applied, the electromechanical transducer operates to displace the wall of the pressure chamber inwardly, rapidly reducing the internal volume of the pressure chamber, and causing the ink composition within the pressure chamber to A part of the amount is jetted as one ink droplet from the nozzle in the direction of physical strength.1. - an inkjet recording method in which, after ejection of a single ink droplet onto a driving nozzle, the volume toI of the pressure chamber is restored to the initial ink equilibrium state, wherein the ink composition has an average molecular weight of 40 An inkjet recording method comprising an aqueous solution containing a vinylpyrrolidone polymer having a weight ratio of .,000 or more and water of at least 50% by weight. (4) The inkjet recording method according to claim 3, wherein the viscosity at 30° C. is 1.8 to 15 centipoise.・