JPH0236276A - Ink and method for recording - Google Patents

Abstract

PURPOSE:To obtain an ink, containing C.I. Food Black 1 as a dye and specific components as a liquid medium and excellent in drying properties of printings on ordinary paper, shape of dots, etc., and discoloration resistance without clogging and suitable for an ink jet method. CONSTITUTION:The objective ink containing a dye which is C.I. Food Black 1 and a liquid medium containing (A) glycerol and/or polyethylene oxide having 3-6 polymerization degree, (B) a nitrogen-containing cyclic compound (e.g., N- methyl-2-pyrrolidone) and/or ether compound of a polyalkylene oxide (e.g., ethylene glycol monomethyl ether), (C) a surfactant (e.g., alkylsulfuric ester salt) and/or a <=5C lower alcohol and (D) water.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to ink and a recording method using the ink, and more particularly to ink and recording methods using the ink, and more particularly to copy paper, report paper, and notebook paper, which is called plain paper and is generally used in offices. The present invention relates to an aqueous ink that can be printed satisfactorily on letter paper and the like and provides a black image with improved indoor discoloration, and a recording method using the ink, particularly an inkjet recording method.

(Prior Art) Conventionally, water-based inks in which water-soluble dyes are dissolved in an aqueous medium have been used as inks for fountain pens, feltbens, etc., and inks for inkjet recording. To prevent ink from clogging in ink ejection nozzles, a water-soluble organic solvent is generally added.

These conventional inks must provide an image with sufficient density, be able to print well on plain paper, not cause clogging in the pen tip or nozzle, and be able to print well on the recording material. Inkjet systems that use thermal energy require good drying properties, little bleeding, excellent storage stability, and especially excellent heat resistance, and the images formed must have sufficient light and water resistance. They are required to have the same gender, etc.

Also, inks of various hues are prepared from dyes of various hues, among which black ink is the most important ink used for both monochrome and full color images. Conventionally, C, I, and Food Black 2 have been mainly used as dyes for these black inks in consideration of various performances (Japanese Patent Laid-Open Nos. 59-93766 and 59-9).
(See Publication No. 3768).

(Problems to be Solved by the Invention) Among the various required performances mentioned above, it is particularly important to achieve both good recording on plain paper and light resistance of images formed on coated paper.

First, the problem with good recording on plain paper is that paper commonly used in offices, such as notebook paper, report paper, copy paper, and letter paper, cannot be used.

In other words, when printing on the various papers mentioned above using conventional inkjet printer ink, the printed ink spreads along the fibers of the paper, resulting in irregular dot shapes and so-called smearing. Ruled lines, small letters, and complex kanji such as those specified as JIS Level 2 were often unclear and difficult to read.

Furthermore, the above-mentioned paper is coated with a "
Because a process called "size" is done in the paper manufacturing process,
When printing with an inkjet printer, it is difficult for the ink to penetrate inside the paper, and the printing area has poor drying properties, so the print may be rubbed by the printer cover and become dirty, or if you touch the printed matter, the ink may get on your hands. There was a problem.

Next, as for the problem of light resistance of images, in the past, fading due to direct sunlight and various types of illumination light was seen as a problem, and these fading problems were solved by selecting dyes with excellent light resistance. There is progress.

However, recently, in addition to these fading problems, the problem of image discoloration has also been brought into focus. In other words, images made with conventional inks not only suffer from fading, but also discoloration. This discoloration does not change much in density, but changes in hue. Particularly in the case of black ink, which is the most commonly used ink, The problem of brown discoloration, in which black changes to brown, is an important problem, and especially in the case of full-color images, image quality rapidly deteriorates due to this brown discoloration.

This problem of brown discoloration progresses even indoors where there is no direct sunlight, and the discoloration is also accelerated by the type of recording material used to form the image. 2, this brown problem was unavoidable.

In particular, in the case of so-called coated paper, in which an ink-receiving layer containing a pigment and a binder is formed on a base material such as paper, in order to improve image quality such as ink color development, clarity, and resolution, In the case of paper, even inks that cause little discoloration problems cause significant brown discoloration, and this problem cannot be solved simply by selecting dyes with good light resistance.

Therefore, it is an object of the present invention to be able to be used in various recording methods, to be particularly suitable for inkjet printers, and to solve the problems that existed with conventional inks, namely, not only with coated paper but also with fibers on the recording surface. An object of the present invention is to provide an ink that solves problems such as ink bleeding and slow drying of printed matter when printed on exposed recording materials, and a recording method using the ink.

Another object of the present invention is to provide an ink and a recording method that can produce images that do not cause the problem of brown discoloration even on coated paper.

(Means for solving problems) The above objects are achieved by the present invention as described below.

That is, the present invention consists of two inventions, and the first invention is an ink containing a dye and a liquid medium, in which the dye is c, r, foot black 1, and the liquid medium is (a) glycerin and/or polymer. Polyethylene oxide having a carbon content of 3 to 6, (b) a nitrogen-containing cyclic compound and/or an ether compound of polyalkylene oxide, (c) a surfactant and/or a lower alcohol having 5 or less carbon atoms, and (d) water. The second invention is an ink characterized by:
In a recording method performed by applying ink to a recording material, the ink contains a dye and a liquid medium, the dye is c, r, or food black 1, and the liquid medium is (a) glycerin and/or polymerization degree 3. to 6 polyethylene oxide, (b) a nitrogen-containing cyclic compound and/or an ether compound of polyalkylene oxide, (c) a surfactant and/or a lower alcohol having 5 or less carbon atoms, and (d) water. This is a recording method that

(Function) By selecting a specific dye as the ink dye and selecting the composition of the liquid medium, it is possible to improve the ink's storage stability, clogging prevention, ejection stability, frequency response, heat resistance, etc. Provided is a black ink which has excellent physical properties and which provides images with problems such as bleeding, density and indoor discoloration, ie, brown discoloration, which are solved even on plain paper as well as coated paper.

In addition, in the second aspect of the present invention, it is possible to provide a high-density black image without bleeding or browning even on coated paper using the above ink.

(Preferred Embodiments) Next, the present invention will be described in more detail by citing preferred embodiments.

The black dyes used in the ink of the present invention include C, I,
Food Black 1 is a bluish black color, so other toning dyes may be blended with this dye to eliminate the blue tinge and enhance jet blackness.

The amount of the dye used in the ink of the present invention is not particularly limited, but - numerically, it is 0.1 to 15% by weight, preferably 0.3 to 10% by weight, more preferably 0.3 to 10% by weight, based on the total weight of the ink. The amount accounts for 0.5 to 5% by weight.

The aqueous medium used in the ink of the present invention has a specific composition, and by having this composition, various physical properties required of the ink are achieved, such as prevention of image bleeding, prevention of dye migration, and storage stability. It has been found that properties such as performance, ejection stability, frequency response, and heat resistance are improved.

The liquid medium of the ink of the present invention contains (a) glycerin and/or polyethylene oxide with a polymerization degree of 3 to 6 as a component that improves the preservability and clogging prevention properties of the ink, and these components account for approximately It is within the range of 1 to 30% by weight, preferably 2 to 25% by weight, and more preferably 3 to 20% by weight. Outside this range, the storage stability and clogging prevention properties may become unsatisfactory, or the paper may become unsatisfactory. It becomes impossible to keep good records.

In addition, in the present invention, (b) a nitrogen-containing cyclic compound and/or a nitrogen-containing cyclic compound and/or a nitrogen-containing cyclic compound are used as components for improving color development, density improvement, and ejection stability of the dye.
or an ether compound of polyalkylene oxide, and these components account for about 0.1 to 50% by weight, preferably 0.5 to 35% by weight, and more preferably 1 to 20% by weight in the total amount of the ink. , outside this range, the above performance becomes unsatisfactory.

Examples of the nitrogen-containing cyclic compound mentioned above include N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, etc., and examples of the ether compound of polyalkylene oxide include ethylene glycol Mono- or dimethyl (or ethyl) ether, diethylene glycol mono- or dimethyl (or ethyl) ether, triethylene glycol mono- or dimethyl (or ethyl)
Examples include ether, tetraethylene glycol mono- or dimethyl (or ethyl) ether, and the like.

Furthermore, in the present invention, (c) a surfactant and/or a lower alcohol having a carbon number of 5 or less is included as a component for improving the frequency response and fixing properties of the ink, and among these components, the surfactant accounts for less than 1% of the total amount of the ink. About 0.001 to 2% by weight, preferably 0.005 to 1ii%, more preferably 0.0%
The content is in the range of 1 to 0.5% by weight, and outside this range, the above performance becomes unsatisfactory. In addition, the lower alcohol is about 0.1 to 15% by weight, preferably 0.
．． The content is in the range of 3 to 10% by weight, more preferably 0.5 to 5% by weight, and outside this range the above performance becomes unsatisfactory.

Examples of the surfactants include fatty acid salts, alkyl sulfate ester salts, alkylbenzene sulfonates, alkylnaphthalene sulfonates, dialkyl sulfosuccinates, alkyl phosphate ester salts, naphthalene sulfonic acid formalin condensates, polyoxyethylene alkyl Sulfate ester salt, polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkylamine, glycerin fatty acid ester, oxyethylene oxypropylene block polymer Examples of the lower alcohol include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol,
Examples include ec-butyl alcohol, tert-butyl alcohol, isobutyl alcohol, and pentyl alcohol.

Further, the water used (d) is preferably deionized water, and accounts for 40% by weight or more, preferably 60% by weight, more preferably 80% by weight or more of the entire ink, and if the amount of water is small, it will not be formed. This is not preferable because a large amount of low-volatile organic solvent remains in the resulting image, causing problems such as dye migration and image blurring.

In addition to the above-mentioned components, the ink of the present invention may optionally contain:
It may include pH adjusters, viscosity adjusters, surface tension adjusters, and the like. Examples of pH adjusting agents used in the above ink include various organic amines such as jetanolamine and triethanolamine, and inorganic inorganic hydroxides such as alkali metal hydroxides such as sodium hydroxide, lithium hydroxide, and potassium hydroxide. Examples include alkaline agents, peroxide salts such as lithium acetate, organic acids, and mineral acids.

The ink of the present invention as described above has a viscosity of 1 at 25°C.
20 cP to 20 cP, preferably 1 to 10 cP, more preferably 1 to 3 cP, and a surface tension of 30 dyne/cI1
1 or more, preferably 40 dyne/cm or more, pH
It is preferable that the material has physical properties of about 4 to 10.

The recording method of the present invention is a recording method characterized by using the above-mentioned ink, and the recording method and recording material are not particularly limited, but in particular, the recording method is an inkjet method, and the recording material is plain paper. Of course, from the viewpoint of light resistance, the method of using coated paper is particularly effective.

The inkjet method may be any conventionally known method and is not particularly limited, but in the present invention, for example, the method described in Japanese Patent Application Laid-Open No. 54-59936 is used, in which the ink is rapidly heated by the action of thermal energy. A method is useful in which a volume change is caused and ink is ejected from a nozzle by the acting force caused by this state change.

In other words, with this method, in the case of conventional ink, there was a risk that foreign matter would settle on the heat generating head in the device, causing problems such as ink failure to eject, but the ink of the present invention can prevent such foreign matter from being deposited. Stable recording is possible because no deposits occur.

The recording material used in the present invention can be any recording material such as general plain paper, high-quality paper, coated paper, plastic film for OHP, etc., but especially when coated paper is used, light resistance A remarkable effect is produced in terms of sex.

These coated papers are made of paper such as silk paper or high-quality paper, and have an ink-receiving layer that serves as a pigment and binder on the surface to improve color development, clarity, dot shape, etc. with ink. This is the purpose.

In the case of these coated papers, fine pigments such as synthetic silica with a BET specific surface area of 35 to 650 rn''/g are used as pigments to provide images with excellent color development and clarity, but conventional inks cannot be used. When using black ink, the problem of brown discoloration is particularly noticeable over time, although the theoretical reason is unknown, and this is a major problem not only for black monochrome images but also for full color images. .

In addition, similar to these coated papers, recording materials that have a thin layer of pigment and binder on a paper base material, and in which fibers of the base paper are mixed, also cause similar problems. There is.

It has been found that even when a black monochrome image or a full color image is formed using the ink of the present invention on the coated paper as described above, the problem of brown discoloration as described above does not occur. Therefore, according to the method of the present invention, the BET specific surface area is 35 to 6.
Recorded images that do not cause discoloration indoors for a long time using not only coated paper using a pigment of 50 rn"/g, but also coated paper using a pigment with a BET specific surface area of less than that, plain paper, and any other recording material. can be provided.

Incidentally, although the inkjet recording method and the various recording materials described above are publicly known and have been proposed by the applicant, these recording methods and recording materials may be used as they are in the present invention. Can be used as an official.

(Example) Next, the present invention will be explained in more detail by giving examples and comparative examples. It should be noted that unless otherwise specified, the terms in the text or % are based on weight.

Examples 1 to 6 The following components were mixed, sufficiently stirred to dissolve, and then pressurized using a Fluorobore filter (manufactured by Sumitomo Electric Industries, Ltd.) with a pore size of 0.45 μm to prepare 6 types of inks of the present invention. did.

-61 ink c, r, food black 1 3 parts glycerin 15 parts triethylene glycol monomethyl ether 2 parts Pluronic L-44 (trade name, nonionic surfactant, manufactured by Asahi Denka) o, oi parts water
80 parts --2 parts c, r, footblack 1 2 parts glycerin 12 parts N-methyl-2
-Pyrrolidone 3-part Emulgen PP150 (
Product name, nonionic surfactant, manufactured by Kao)
0.02 part water
83 parts Da 3 ink 1 c, r, food black 3 parts triethylene glycol 10 parts tetraethylene glycol dimethyl ether 4 parts Emulgen 985 (trade name, nonionic surfactant, manufactured by Kao) 0.1 part water
83 parts 4 parts C, I, food black 1 4 parts tetraethylene glycol 2 parts glycerin
Part 6 1,3-dimethyl-2-
imidazolidinone 5 parts ethanol
3 parts water
8 parts - 5 Ink JC, I, Food Black 1 3 parts Pentaethylene glycol 10 parts Tetraethylene glycol dimethyl ether 4 parts Emulgen PP150 (trade name, nonionic surfactant, manufactured by Kao) 0.1 part Water
83 parts - m-6 ink C, I, food black 1 3 parts triethylene glycol 10 parts isopropanol 4 parts Emulgen PP150
(Product name, nonionic surfactant, manufactured by Kao)
0.1 part water
Six types of comparative inks were prepared in the same manner as in the examples.

~1.C, I, Food Black 2 2.5 parts diethylene glycol 30 parts N-methyl-
2-pyrrolidone 15 parts water
Amount for a total of 100 parts 2 Ink c, r, food black 2 3 parts Glycerin 15 parts Triethylene glycol monomethyl ether 2 parts Pluronic L-44 (trade name, nonionic surfactant, manufactured by Asahi Denka) 0 .01 part water
80 parts'' 3 inks c, r, foot black 1 3 parts diethylene glycol 15 parts triethylene glycol monomethyl ether 2 parts Pluronic L-44 (trade name, nonionic surfactant, manufactured by Asahi Denka) o, or part water
80 parts -4, Footblack 1 3 parts Polyethylene oxide (degree of polymerization 7) 15 parts Triethylene glycol monomethyl ether 2 parts Pluronic L-44 (trade name, nonionic surfactant, manufactured by Asahi Denka) 0 .01 part water
80 parts -5 ink C, I, foot black 1 3 parts glycerin 15 parts triethylene glycol monomethyl ether 2 parts water 80
Part-6 Ink C, I Food Black 1 3 parts Glycerin 15 parts Ethylene glycol 2 parts Pluronic L-44 (trade name, nonionic surfactant, manufactured by Asahi Denka)
0.01 part water
80 copies Usage example: Inkjet printer that uses a heating element as an ink ejection energy source (nozzle size 22X: 13μm)
, 256 nozzles, IKHz drive) Examples 1 to 6
And when printing was carried out on the following recording materials A to C using the inks of Comparative Examples 1 to 6, the dryness of the print, the rate of occurrence of bleeding, clogging when reprinting after stopping printing, and the long term of printing. The clogging recovery property, frequency response, and color fastness during reprinting after stopping were evaluated, and the obtained results are shown in Tables 1 and 2.

Recording material A: Inkjet coated paper NM (product name,
(Manufactured by Mitsubishi Paper Mills) Recording material B: Inkjet coated paper FC-3 (product name, manufactured by Jujo Paper Mills) Recording material C: Coby paper Canon PAPERDRY
(Product name, manufactured by Canon Sales ■) (Evaluation method and evaluation criteria) (1) Printing dryness Regarding the printing dryness, after printing alphanumeric characters with a printer on commercially available recording material C, 1O120,30 ,40,5
After 0 and 60 seconds, it was rubbed with a filter paper [Toyo Roshi Co., Ltd. No. 2 (trade name)] and judged based on the number of seconds until the printed area was no longer dirty (at 20°C ± 5°C, 50 ± 1O% RH). measurement>.

O: Within 20 seconds △: Within 20 to 40 seconds After leaving for more than 1 hour, the number of bleeding dots was counted using a microscope and expressed as a percentage (20±5℃, 50±1O%RH).
(Printed in ).

0.10% or less △: 11 to 30% ×: 31% or more (3) Printing - Clogging when reprinting after stopping Printing - For clogging when reprinting after stopping, check the printer according to the specified settings. After filling with ink and printing alphanumeric characters on the recording material C for 3 minutes continuously, stop printing, leave it for 3 minutes with no cap etc., then print alphanumeric characters again and check if the characters are faded. Judgment was made based on the presence or absence of defective parts such as defects and defects (left at 20±5° C. and 50±10% R1-1).

○No defects starting from the knee letter.

△A part of the knee letters is faded or missing.

×The knee character cannot be printed at all.

(4) Recovery from clogging when reprinting after a long printing stop After filling the printer with the specified ink and printing alphanumeric characters on the recording material C continuously for 10 minutes, stop printing and replace the cap, etc. After leaving it unused for 7 days, perform an operation to recover from clogged nozzles.
I want to judge whether normal printing without defects etc. is possible at 60℃, 1
Leave at 0±5%RH →.

○: Normal printing is possible after 1 to 5 recovery operations.

△: Normal printing is possible after 6 to 10 recovery operations.

X: Normal printing is possible with f1 or more recovery operations.

(5) Frequency response The driving frequency was set to 2 Hz, and the printing condition of the obtained printed matter, that is, the condition of scratches and white spots, and the condition of poor landing points such as splash and wobbling, were observed and evaluated with the naked eye.

O: The followability of the ink to the frequency is good, and no blurring, white spots, or poor landing points are observed in both solid printing and character printing.

△: No fading or white spots are observed in character printing, but poor impact points are observed in some areas. Furthermore, in solid printing, fading, white spots, or fading are observed in about 1/3 of the entire print.

×: There are many scratches and white spots in solid printing, and there are also many scratches and poor landing points in character printing.

(6) Colorfastness After printing a 100111×30 mm rough black pattern on recording materials A, B, and C at a driving frequency of 1 to 1 Hz, the ozone concentration was always 0.1±o as a method of accelerating discoloration.

The printed matter was placed in a light-shielded tank maintained within the range of 5% by volume.
The color difference ΔE"ab of the printed matter after the test surface was measured after being left for 0 minutes (JIS Z87301.: compliant).

O: ΔE”ab<5 △: 5≦ΔE”ab≦10 × : ΔE”ab>10 Tsui Yj-j momme (evaluation result) Chew 3j [i and hill 1 sun] Σlimb test ○ ○ ○ O ○ ooooo ○ Salmon - Hen Isshiki Ichiku Gopest number za answer and Salmon Ichihen 12 - and (A) (B) (c) Nail (≦Rij〈 (Evaluation result) Utaj Shihe Earthshii Sex 5n Side” 1 state ○ △ △ △ △ Yen” 宸变性性 △ ○ ○ △ × △resistant-”L
” Whale-ability (A) XXOOOO (B) XX ○ OO0 (c) Δ △ ○ ○ OO (Effect) According to the present invention as described above, - Drying of printing on plain paper/＼ which is numerically required In addition to having excellent performance in terms of color and dot shape, it has also become possible to form images that do not clog and have excellent color fastness even on coated paper.

Claims (4)

[Claims] (1) In an ink containing a dye and a liquid medium, the dye is C
, I, Food Black 1, and the liquid medium is (a) glycerin and/or polyethylene oxide with a degree of polymerization of 3 to 6, (b) a nitrogen-containing cyclic compound and/or an ether compound of polyalkylene oxide, (c) An ink characterized by containing a surfactant, a lower alcohol having 5 or less carbon atoms, and (d) water. (2) In a recording method performed by applying ink to a recording material, the ink contains a dye and a liquid medium, the dye is C, I, or Food Black 1, and the liquid medium is (a) glycerin and/or Contains polyethylene oxide with a polymerization degree of 3 to 6, (b) a nitrogen-containing cyclic compound and/or an ether compound of polyalkylene oxide, (c) a surfactant and/or a lower alcohol having 5 or less carbon atoms, and (d) water. A recording method characterized by. (3) The recording method according to claim 2, wherein recording is performed using an inkjet method. (4) The recording method according to claim 2, wherein the recording material has an ink-receiving layer made of a pigment and a binder on its surface.