JP2801017B2 - Inkjet recording method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ink jet recording method, and more particularly to an ink jet recording method using plain paper generally used in offices and homes.

[Prior Art] Conventionally, various methods have been studied and proposed for an inkjet recording method. Above all, as for the ink jet recording method in which paper is used as a recording material and recording is performed by a drop-on-demand method, since the equipment can be downsized and its application range is extremely wide, the mechanism of ink, paper, and the printer, etc. A detailed study has been made.

However, there are several problems with conventional drop-on-demand inkjet printers, the largest of which are notebooks, report paper, copy paper, stationery,
That is, paper generally used in offices and homes, such as postcards, cannot be used.

That is, when printing is performed on the above-described various types of paper using a conventional drop-on-demand type ink jet printer, the printed ink spreads along the paper fibers, and the dot shape becomes indefinite. Because of the so-called bleeding, thin ruled lines, fine characters, and complicated kanji as stipulated in the JIS second standard are often unclear and difficult to see.

In addition, when the above-mentioned paper is generally written with a writing implement using a fountain pen water-based ink, bleeding hardly occurs,
In many cases, a process called size is performed in the papermaking process.When printing with an ink-jet printer, the ink does not easily penetrate into the paper, so the dryness of the printed portion of the ink deteriorates, and printing is performed with the printer cover There are problems such as rubbing and smearing, and ink sticking to the hand when the printed matter is touched by hand.

Therefore, various improvements have been made for the purpose of improving bleeding and drying property of printing. For example, a method of making the pH of the ink highly alkaline, a method of adding a large amount of a surfactant to the ink, a method of adding a water-soluble polymer to the ink,
Further, a method of providing a heating and drying unit in a recording apparatus and preheating and heating the recording paper before and after printing to promote drying and fixing of the ink has been already attempted. The method of making the pH of the ink highly alkaline is dangerous when the ink is touched by hand, and the bleeding and drying properties may not be good for paper using a certain sizing agent. There are drawbacks. Also, in the method of adding a large amount of a surfactant, bleeding occurs extremely depending on the paper, or the ink retreats from the orifice surface depending on the condition of the printer head, and the ink does not discharge. Troubles such as the entire surface being wet and no ink being ejected were observed. In addition, the method of adding a water-soluble polymer to the ink has some effects on the bleeding and the drying property of the print, but the ink tends to dry even at the tip of the orifice of the printer head, and the printer is not printed. However, if left in a room for several minutes, a problem arises in that ejection is not performed normally. Further, when the heating and drying means is employed, the thermal effect on the recording head, that is, the problem of defective ink ejection, or the mechanical and electrical obstacles of the apparatus, and the operator must be protected from burns, etc. However, it is not always a good means because it is necessary to take measures against them.

In addition, when performing ink-jet color recording using a plurality of heads in order to realize colorization, image quality is deteriorated due to bleeding of overlapping portions and border portions of color ink, and furthermore, poor ink absorption at overlapping portions. In particular, the problems caused by insufficient drying and fixing of the ink on the recording paper, such as the problem of the recording paper being wavy, are particularly remarkable. Therefore, the development of ink-jet recording coated paper with improved ink absorption has led to the improvement of these problems, but the components of the coating layer, on the other hand, have reduced color reproducibility and lightfastness. This causes a bad influence on image quality such as a defect, and is a new problem.

[Problems to be Solved by the Invention] An object of the present invention is to provide an inkjet recording method using a water-based ink of a drop-on-demand system, which has a problem that a conventional recording method has, that is, a general office,
It is an object of the present invention to provide an ink jet recording method that solves poor print drying property when recording on plain paper used at home and the like, desirably blurring, and at the same time considers the safety and reliability as a recording apparatus. .

Another object of the present invention is to provide an excellent hue, density,
An object of the present invention is to provide a good inkjet color recording method having saturation.

[Means for Solving the Problems] The present invention relates to an ink jet recording method characterized in that the temperature of ink droplets of aqueous ink discharged from an orifice by a discharge signal becomes 65 ° C. or higher at a printing position on a recording medium. In particular, in an ink jet recording method using aqueous inks of a plurality of colors, (A) the temperature of an ink droplet ejected from an orifice by an ejection signal is 65 ° C. or higher at a printing position of a recording medium; (C) the volume of each of the ink droplets is 40 pl or less; and (D) the temperature of the recording medium at the printing position is 40 ° C. to 70 ° C. (A) the temperature of the ink droplet ejected from the orifice by the ejection signal is 65 ° C. or higher at the printing position of the recording medium; (C) the volume of each ink droplet is 40 pl or less, and (D) the temperature of the recording medium at the printing position is 40 An ink jet recording method characterized in that the ink is preheated to a temperature of from 70 to 70 ° C.

In the inkjet recording method of the present invention, it is an important condition to use a recording head that ejects ink droplets using thermal energy. That is, the ink droplets ejected from the recording head are ejected as droplets having a considerably higher temperature than the environment due to the high heat generated when the heating element is foamed.

Since the temperature of the ink drops drops even when the flying distance from the tip of the orifice to the recording medium is about 0.5 to 1.5 mm, if the temperature of the ink drops at the printing position of the recording medium drops below 60 ° C, the drying property of the print If the temperature is lower than 65 ° C., the residual ink that cannot be fixed on the recording medium promotes irregular bleeding of dots, which may cause deterioration of print quality.

When the temperature of the ink droplet at the printing position of the recording medium becomes 60 ° C. or higher, the viscosity of the ink is considerably reduced, and the fluid resistance inside the medium at the time of collision with the recording medium is reduced, so that the ink is easily penetrated. Become. Further, since the evaporation rate on the medium surface is high, the fixing and drying are further promoted.

Therefore, irrespective of the temperature of the recording medium, if the temperature of the recording head is controlled so that the temperature of the ink droplets at the printing position of the recording medium is always 60 ° C. or higher, the drying property of the print is good and the ink If the temperature of the recording head is controlled so that the temperature of the droplet is 65 ° C. or higher, high-quality ink jet recording with less occurrence of bleeding can be performed.

However, when two or three colors are overprinted, it is desirable to further reduce the ink volume at the printing position on the recording medium and take preheating means before and after printing on the recording medium. More specifically, regarding the setting of the heating and drying means, first, the influence of heat on the recording head, that is, the problem of clogging due to the promotion of ink evaporation at the tip of the orifice, or the mechanical or electrical failure of the recording apparatus, and the operator The preheating temperature of the recording medium is set to 40 ° C. to 70 ° C. in order to avoid problems such as protecting the
In the range of ° C.

Further, regarding the drying and fixing within the above-mentioned residual heat temperature range, if the volume at the printing position of the ink droplet ejected from the orifice by the ejection signal is 40 pl or less, the recording medium is not overprinted with two colors or less. Is ordinary plain paper,
Good dry fixation is obtained. Further, if the recording medium is a coated paper for ink jet recording excellent in ink absorbency,
Good dry fixation can be obtained even for two or three colors of overprinting. That is, the amount of ink per unit area on the recording medium and the ink absorbency of the recording medium can be cited as important factors that affect dry fixing.

As the recording agent used in the present invention, any of dyes and pigments can be used, and a color index (Color index) can be used.
Almost all of the water-soluble acid dyes, direct dyes, basic dyes and reactive dyes described in x) can be used, and pigments can also be used in a state of being dispersed in an aqueous liquid medium. It is.

In addition, even if it is not described in the color index, it can be used as long as it is a water-soluble dye, and also about the pigment, even if not described in the color index,
Any material that can be dispersed in an aqueous liquid solvent can be used.

The amount of these recording agents used is not particularly limited, but is generally 0.1 to 15% based on the total weight of the recording liquid.
A range of weight percent is preferred.

In addition, the ink of the present invention may contain, in addition to the above components, a water-soluble organic solvent, a surfactant, a pH adjuster, a rust inhibitor, a preservative, an antioxidant, an evaporation promoter, a chelating agent, if necessary. Various additives such as an agent and a water-soluble polymer may be added.

Specifically, as the water-soluble organic solvent, for example, methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol,
C1-C4 alkyl alcohols such as sec-butyl alcohol, tert-butyl alcohol and isobutyl alcohol; amides such as dimethylformamide and dimethylacetamide; ketone or keto alcohols such as acetone and diacetone alcohol; tetrahydrofuran and dioxane Polyalkylene glycols such as polyethylene glycol and polypropylene glycol; alkylenes such as ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol and diethylene glycol Group is 2
Alkylene glycols containing 6 carbon atoms; glycerin; lower alkyl ethers of polyhydric alcohols such as ethylene glycol methyl (or ethyl) ether, diethylene glycol methyl (or ethyl) ether, triethylene glycol monomethyl (or ethyl) ether; N-methyl-2-pyrrolidone, 1,3-dimethyl-
2-imidazolidinone, triethanolamine, sulfolane and the like.

Examples Examples 1 to 3, Reference Example 1 and Comparative Examples 1 to 3 Next, the present invention will be described more specifically. In the examples of ink, all percentages indicate weight%. The inks (1) to (7) in Table 1 were applied to an ink jet printer BJ-13.
0 (Canon) was loaded on a modified product and printed on commercially available copy paper. Tables 2 and 3 show the recording conditions and recording characteristics.

(Evaluation Method and Evaluation Criteria) Temperature Measurement of Ink Droplet at Printing Position A thermocouple is provided on the surface of the pteran holding the recording medium, and the temperature of the ink drop ejected from one orifice by one ejection signal is electrically measured. It was measured by letting it be recognized. The temperature of the ink droplets was adjusted by controlling the temperature of the recording head.

Drying of printing For drying of printing, after printing alphanumeric characters on a commercial continuous slip paper with a printer, 10, 20, 30, 40, 50 and 60 seconds later, filter paper [Toyo Filter Paper No. 2 (trademark) Name)], and the determination was made based on the number of seconds until the printed portion was not stained (at 20 ° C.
± 5 ° C, 50 ± 10% RH).

Print quality For print quality, after printing on a commercially available copy paper, leave it for one hour, dry the printed matter sufficiently, and then bleed at the dot level and evaluate the sharpness of the edge (25 ° C, 60% Evaluation under RH environmental conditions).

Examples 5 to 8 and Comparative Examples 4 to 15 Inkjet color recording was performed on two types of recording paper, commercially available copy paper and inkjet coated paper, using a modified inkjet printer BJ-130 (manufactured by Canon). Tables 4 and 5 show the recording conditions at that time, and the results of image evaluation and nozzle clogging.

 The following two types of ink were used.

Ink Example 8 <Yellow Ink> Ethylene glycol 5% Glycerin 10% CI Direct Yellow _{86 2% H 2 O 83%} < Magenta Ink> Ethylene glycol 5% Glycerin 10% CI Direct Red _{227 2% H 2 O 83%} < Cyan Ink > ethylene glycol 5% glycerin 10% CI direct Blue _{199 2% H 2 O 83%} < black ink> ink ink example 9 <yellow ink ink example 1> diethylene glycol 20% glycerin 15% CI direct yellow 86 _2% H 2 O 63% <magenta ink> diethylene 20% glycerin 15% CI direct Red _{227 2% H 2 O 63%} < cyan ink> diethylene 20% glycerin 15% CI direct Blue _{199 2% H 2 O 63%} < black ink> ink example 1 ink (Evaluation and Measurement Method) Temperature Measurement of Ink Droplets at Printing Position A thermocouple is provided on the surface of a platen that holds a recording medium, and the temperature of ink drops ejected from one orifice by one ejection signal is electrically measured. It was measured by recognizing. The temperature of the ink droplets was adjusted by controlling the temperature of the recording head.

Measurement of volume of ink droplet at printing position After performing solid recording in which ink droplets are ejected from all nozzles of the recording head, one drop of ink is calculated from the reduced amount of ink in the ink tank connected to the nozzle and the solid recording area. Was measured.

Measurement of preheating temperature of recording medium A heating platen attached to an inkjet printer BJ-130 (manufactured by Canon Inc.) was provided with a temperature sensor to control the temperature of the heating element, thereby adjusting the temperature to a predetermined temperature.

Evaluation of nozzle clogging After giving a discharge signal to a predetermined nozzle of the recording head and printing continuously for 10 minutes, quickly giving a discharge signal to the remaining unused nozzles and printing, The presence or absence of defective portions such as blurring and chipping of the printed portion was determined (measured at 20 ° C. ± 5 ° C., 50 ± 10% RH).

The ink used in the present invention preferably has a water content of 70% or more. Also, when using an ink having a water content of less than 70%, it is preferable that the temperature of the ink droplet at the printing position on the recording medium be 65 ° C. or higher.

[Effects of the Invention] As described above, according to the present invention, the dryness of printing can be improved even when printing is performed on commercially available general paper, for example, paper such as notebook, report paper, copy paper, stationery, and postcard. A recording method which is extremely good and has good print quality can be obtained.

Further, according to the present invention, good ink jet color recording can be obtained not only for special ink jet paper but also for ordinary plain paper. In particular, since quick drying and fixing can be realized even for two or three overstrikes, a wide range of color reproducibility is possible, and a high-definition color image can be obtained.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-169655 (JP, A) JP-A-61-24455 (JP, A) JP-A-62-288075 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) B41J 2 / 01,2 / 175,2 / 21

Claims (3)

(57) [Claims] 2. An ink jet recording method according to claim 1, wherein the temperature of the ink droplet of the aqueous ink discharged from the orifice by the discharge signal becomes 65 ° C. or higher at the printing position of the recording medium. 2. An ink jet recording method using aqueous inks of a plurality of colors, wherein: (A) the temperature of an ink droplet ejected from an orifice by an ejection signal is 65 ° C. or higher at a printing position on a recording medium; (C) the volume of each of the ink droplets is 40 pl or less; and (D) the temperature of the recording medium at the printing position is 40 ° C. to 70 ° C. An ink jet recording method, characterized in that: 3. An ink jet recording method using aqueous inks of a plurality of colors, wherein (A) the temperature of an ink droplet ejected from an orifice by an ejection signal is 65 ° C. or higher at a printing position on a recording medium; The recording medium is a coated paper for ink jet recording having excellent ink absorbency; (C) the volume of each of the ink droplets is 40 pl or less; and (D) the temperature of the recording medium at the printing position is An ink jet recording method, which is preheated to 40 ° C to 70 ° C.