JPH10151733A - Ink jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet printer not generating a curl in recording paper. SOLUTION: An ink jet printer is constituted of a paper feed roller 2, a paper presser 3, a printing head (ink jet head) 4, a platen 5, a curl preventing soln. 6, a curl preventing soln. coating roller group 7 and a heater 8. In this case, the liquid containing at least water (curl preventing soln.) 6 is bonded to the surface B on the rear side with respect to the printing surface A of recording paper 1 in an amt. same to or almost same to but less than the amt. of ink required in printing by the curl preventing soln. coating roller group 7. Since the fibers of the printing surface A and the non-printing surface B are almost equally stretched, no curl is generated in the paper 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an ink jet printer, and more particularly, to an ink jet printer in which recording paper is prevented from curling.

[0002]

2. Description of the Related Art In recent years, ink jet printers have rapidly spread due to advantages such as low noise and low running cost, and have been used not only for ink jet printer paper but also for copy paper (of an electrophotographic copier) used in general offices. Printers that can print are also on the market. Also, so-called co-papers having both electrophotographic copier suitability and ink jet printer suitability have been released from various companies.

[0003]

However, when the amount of ink becomes extremely large due to, for example, almost solid printing,
In the case of these copy sheets or co-sheets, a problem of curl (paper curl) occurs. To remedy this problem,
For example, in the invention described in Japanese Patent Application Laid-Open No. Hei 7-329413, a scratch or a hole is formed on the back side of the paper. However, in this method, the paper strength is weakened, and a problem such as tearing with a small amount occurs. Further, for example, in the invention described in JP-A-7-205543, the expandable particles in the paper are expanded, but the production method must be complicated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide an ink jet printer in which a recording sheet is prevented from curling.

[0005]

According to a first aspect of the present invention, in an ink jet printer, a liquid containing at least water is attached to the back side of a printing surface of a recording medium in an amount equal to or less than the amount of ink required for printing. Thus, the fibers on the printing surface and the non-printing surface are evenly stretched to prevent curling.

According to a second aspect of the present invention, in the first aspect of the present invention, an application roller is used as a means for adhering a liquid containing at least water on the back side of the recording medium printing surface, and thus water droplets are scattered. Instead, a liquid containing water is made to adhere to the paper.

According to a third aspect of the present invention, in the first or second aspect, a heater for drying the recording medium after attaching a liquid containing at least water to the back side of the recording medium printing surface is provided. The feature is to prevent sheets from overlapping.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic diagram showing a main part of an ink jet printer according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a recording paper (paper receiving), 2 denotes a paper feed roller, 3 is a paper holder, 4 is a print head (inkjet head), 5 is a platen, 6 is an anti-curl liquid, 7 is a group of anti-curl liquid application rollers, and 8 is a heater.
A liquid (curling prevention liquid) 6 containing at least water is applied to the surface B on the back side of the printing surface A of the recording paper 1 by an amount equal to or less than the amount of ink required for printing. The adhesive is applied by the application roller group 7 so that the fibers on the printing surface A and the non-printing surface B extend substantially evenly, thereby preventing the paper 1 from curling.

FIG. 2 shows an example of a print pattern (solid print pattern) when printing is performed by the ink jet printer shown in FIG. 1. FIG. 3 shows a case where the print is left in an environment of 20 ° C. and 65% for 12 hours after printing. 1 shows the evaluation of the curl of the receiving paper. However, in the degree of curl shown in FIG. 3, ○ indicates that the curl at the front end of the paper when left on the horizontal surface was less than 30 °, and Δ indicates that the paper when left on the horizontal surface for one day. The curl of the front end is 30 ° or more and less than 90 °, × indicates that the curl of the front end of the paper when left on a horizontal surface for one day is 90 °
The above is mentioned.

[0010] The mechanism of curling in an ink jet printer is as follows: (1) By printing, fibers only on the printing surface are absorbed and expanded by ink droplets; and (2) During printing, the paper is fixed by a platen or the like. Cockling (wavy) occurs but the paper as a whole is not curled,
(3) If the paper is ejected and is no longer fixed after printing is completed, the fibers on the printing surface only dry and shrink over time. In this case, since the fibers on the printing surface and the non-printing surface are uniformly stretched, curling can be prevented. In the present invention, the ink is not particularly limited, and a normal ink is preferably used.

The following organic solvents can be used for the anti-curl liquid to be adhered to the non-printing surface of the present invention for the purpose of preventing drying and improving wettability. Ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,5 pentanediol, 1,6 hexanediol, glycerol, 1,2,6-hexanetriol, 1,2,4-butanetriol, 1,2 , 3-butanetriol, polyhydric alcohols such as petriol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, propylene glycol monoethyl ether Such as polyhydric alcohol alkyl ethers, ethylene glycol monophenyl ether, and ethylene Polyhydric alcohol aryl ethers such as glycol monobenzyl ether; N- methyl-2-pyrrolidone, N- hydroxyethyl-2-pyrrolidone, 2-pyrrolidone, 1,3
Nitrogen-containing heterocyclic compounds such as -dimethylimidazolidinone and ε-caprolactam; amides such as formamide, N-methylformamide, formamide, N, N-dimethylformamide; monoethanolamine, diethanolamine, triethanolamine, monoethylamine; Diamines, amines such as triethylamine, dimethyl sulfoxide, sulfolane, sulfur-containing compounds such as thiodiethanol, propylene carbonate, ethylene carbonate,
γ-butyrolactone and the like. These solvents are used alone or as a mixture of two or more.

Anionic, nonionic and amphoteric surfactants and monohydric alcohols can be used for the purpose of improving wettability and permeability. In addition to the above-mentioned solvent and surfactant, conventionally known additives can be added. For example, as the antiseptic / antifungal agent, sodium debidroacetate, sodium sorbate, sodium 2-pyridinethiol-1-oxide, sodium benzoate, sodium pentachlorophenol, and the like can be used in the present invention. As a rust inhibitor, acidic sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate,
And dicyclohexylammonium nitrite. In addition, a water-soluble ultraviolet absorber and a water-soluble infrared absorber can be added according to the purpose.

The anti-curl liquid does not need to be uniformly applied, but rather, it is preferable to provide a mechanism for adjusting the amount of adhesion according to the image signal (ink application amount). For example, in the case of the application roller system, the amount of application can be adjusted by adjusting the gap or the relative speed between the pumping roller and the application roller. Further, it is preferable to provide control such that the strength of the heater is increased when the amount of the curl preventing liquid is large, and reduced when the amount of the curl preventing liquid is small.

(Example) A composition having the following formulation was stirred and dissolved at 60 ° C., allowed to cool at room temperature, and adjusted with a 10% aqueous solution of lithium hydroxide so that the pH became 8.5. Filtration was performed with a filtration filter having a filtration area of 4 cm ² and a filtration pore size of 0.2 μm to prepare an ink for an inkjet printer. Cyan dye FastCyan2 (manufactured by Zeneca) 3.0% by weight Diethylene glycol 15.0% by weight Glycerol 5.0% by weight Surfactant ECTD3NEX (manufactured by Nikko Chemicals) 1.0% by weight 0.4% by weight of ion exchange water

Further, the composition of the following formulation was dissolved with stirring at 60 ° C., as an active filtration area 4 cm ^2, filtered pore size 0.2μm
The resulting mixture was filtered through a filtration filter to prepare an anti-curl liquid. Diethylene glycol 15.0% by weight Glycerol 5.0% by weight Surfactant ECTD3NEX (manufactured by Nikko Chemicals) 1.0% by weight Preservative and fungicide P-100 (manufactured by Sanai Petroleum) 0.4% by weight Deionized water

With the above ink, the A4 length receiver shown in FIG. 3 is fed in a horizontal direction and solid printing is performed as shown in FIG.
m ² ), the anti-curl solution was applied, and dried with a heater.

[0017]

According to the first aspect of the present invention, in an ink jet printer, a liquid containing at least water is attached to the back side of a printing surface of a recording medium in an amount equal to or less than the amount of ink required for printing. The fibers on the non-print surface can be evenly stretched to prevent curling.

According to a second aspect of the present invention, in the first aspect of the present invention, an application roller is used as a means for adhering a liquid containing at least water on the back side of the recording medium printing surface, so that water droplets do not scatter. Can be made to adhere to the liquid containing water. (If attention is paid only to prevention, for example, it may be sprayed with a spray. However, when printed on plain paper using an inkjet printer commonly used in offices, water resistance is low. Therefore, it is not preferable that water droplets scatter.)

According to a third aspect of the present invention, in the first or second aspect of the present invention, a heater for drying the recording medium is provided after a liquid containing at least water is attached to the back side of the recording medium printing surface. It is possible to prevent paper from overlapping. (Note that if only attention is paid to prevention, paper may be damp, but if it is printed on plain paper with an inkjet printer normally used in offices, it will be difficult to achieve water resistance. Therefore, it is not preferable that the wet printed sheets overlap in continuous printing).

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a main part of an embodiment of an inkjet printer according to the present invention.

FIG. 2 is a diagram illustrating an example of a print pattern when solid printing is performed by the inkjet printer illustrated in FIG. 1;

FIG. 3 is a diagram illustrating a curl degree and evaluation of a sheet after printing.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Recording paper (paper receiving), 2 ... Paper feed roller, 3 ... Paper holding, 4 ... Inkjet head, 5 ... Platen, 6 ... Curl prevention liquid, 7 ... Curl prevention liquid application roller group, 8 ... Heater.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Akiko Konishi 1-3-6 Nakamagome, Ota-ku, Tokyo Stock inside Ricoh Company (72) Inventor Masayuki Kogano 1-3-6 Nakamagome, Ota-ku, Tokyo Stock In Ricoh Company (72) Inventor Takanori Tsukiki 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh Company (72) Inventor Hirotaka Mochizuki 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh Company (72) Inventor Ikuko Yamada 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd.

Claims (3)

[Claims] 2. An ink jet printer according to claim 1, wherein a liquid containing at least water is attached to the back side of the printing surface of the recording medium in an amount equal to or less than an amount of ink required for printing. 2. An ink jet printer using an application roller as means for adhering a liquid containing at least water on the back side of a printing surface of a recording medium. 3. The ink jet printer according to claim 1, further comprising a heater for drying the recording medium after the liquid containing at least water is attached to the back side of the recording medium printing surface.