JPH0684100B2 - Inkjet recording paper - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to an ink jet recording sheet for recording with ink, and particularly, the density of images and characters recorded on the recording sheet is high, and The present invention relates to an inkjet recording sheet made of uncoated paper having excellent image quality.

(B) Prior Art and its Problems The ink jet recording method is one in which minute droplets of ink are ejected according to various operating principles and adhered to a recording medium such as paper to record images, characters, and the like. ,high speed,
It has features of low noise, easy multi-coloring, great flexibility of recording patterns, and unnecessary phenomenon and fixing. It can be rapidly used in various applications as a recording device for various figures and color images including Chinese characters. It is popular. Further, an image formed by a multicolor ink jet system can also be used for multicolor printing by a plate making system or a print that is comparable to printing by a color photographic system, which requires less number of copies. , It is being applied to the full-color image recording field because it is cheaper than the photographic technique.

As a recording medium used in this ink jet recording system, efforts have been made in terms of the apparatus and the ink composition so as to use high-quality paper or coated paper used for ordinary printing and writing. However, as the performance of the inkjet recording apparatus has been improved and the applications have been expanded, such as high speed, high definition and full color of the apparatus, more advanced characteristics have been required for the recording medium. That is, as the recording medium, the density of the ink dots is high, the color tone is bright and fresh, the ink does not flow out or bleed even when the ink dots are overlapped and the ink dots overlap, The lateral diffusion is not too large, and the periphery is smooth and unblurred. Further, it is required that the resistance of the dye when the recorded image is exposed to ultraviolet rays, oxygen in the air, or water is not lowered, and preferably enhanced.

Several proposals have been made in the past to solve these problems. For example, in JP-A-52-53012,
An ink jet recording paper is obtained by wetting a low-sized base paper with a coating material for surface processing, and in JP-A-53-49113, a sheet containing urea-formalin resin powder is impregnated with a water-soluble polymer. Disclosed is an inkjet recording sheet. These general paper type inkjet recording papers absorb ink quickly, but have drawbacks in that the periphery of dots is easily blurred and the dot density is low.

Further, JP-A-55-5830 discloses an ink jet recording paper having a support surface provided with an ink-absorptive coating layer, and JP-A-55-51583 discloses a pigment in a coating layer. An example using non-colloidal silica powder is further disclosed in JP-A-55-118.
Japanese Patent Publication No. 29 discloses an example of a smear paper using a two-layer structure having different ink absorption speeds. These coated paper type inkjet recording papers are better than general paper type inkjet papers in terms of dot shape and reproducibility of color tone of dot density, but dot diameter control, especially bleeding rate is small. It was quite difficult to make a high-resolution recording paper that was held down.

(C) Object of the Invention Here, in order to obtain a recording medium having a high resolution with a small bleeding rate while having an ink absorbing ability,
As a result of various studies, the above-mentioned object was successfully achieved and the present invention was completed.

(D) Structure and Action of the Invention The present invention relates to an inkjet recording sheet for recording by jetting and flying a recording liquid from an orifice, and the recording sheet has a Steckigt sizing degree of 10 seconds or more and Beck's smoothness. The present invention provides an inkjet recording paper made of uncoated paper, characterized by being in the range of 100 seconds to 600 seconds.

The ink jet recording method is a method of ejecting and flying a recording medium from an orifice to perform recording by adhering to a recording surface, and there are various types of recording liquid used from oil ink to aqueous ink. In the present invention, among them, the content of the water-soluble organic solvent in the oil-based ink and the water-based ink is 5 to 95% by weight, preferably 10 to 95% by weight, more preferably 20 to 95% by weight based on the total weight of the recording liquid. Inks with strong penetrability of wt% are especially preferred.

The recording liquid used in the present invention is an ink containing a liquid medium, a colorant and other additives. Examples of colorants include various dyes, inorganic pigments and organic pigments.

As the liquid medium in the case of oil-based ink, for example, methyl alcohol, ethyl alcohol, n-propyl alcohol,
Isopropyl alcohol, n-butyl alcohol, sec
-Butyl alcohol, tert-butyl alcohol, isobutyl alcohol, pentyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, decyl alcohol, benzyl alcohol, etc. alkyl alcohol having 1 to 10 carbon atoms; for example, cyclopentane, hexane, Cyclohexane, heptane,
Aliphatic or aromatic hydrocarbons represented by octane, nonane, decane, undecane, dodecane, tridecane, tetralin, decalin, benzene, toluene, xylene, etc .; for example, halogens such as carbon tetrachloride, trichloroethylene, tetrachloroethane, dichlorobenzene, etc. Hydrocarbons; ethers such as ethyl ether, butyl ether, ethylene glycol-diethyl ether, ethylene glycol monoethyl ether, etc .; such as acetone,
Ketones such as methyl ethyl ketone, methyl propyl ketone, methyl amyl ketone, cyclohexanone; esters such as ethyl formate, methyl acetate, ethyl acetate, phenyl acetate, butyl acetate, ethylene glycol monoethyl ether acetate, ethyl lactate propylene carbonate; ,
Polyhydric alcohols such as diethylene glycol, propylene glycol and glycerin; various other nitrogen-containing heterocyclic solvents such as triethanolamine, dimethylformamide, N-methyl-2-pyrrolidone and 1,3 dimethyl-2-imidazolidinone There are things.

The liquid medium in the case of aqueous ink is water and various water-soluble organic solvents such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol and tert-butyl alcohol. , C1-C4 alkyl alcohols such as isobutyl alcohol; amides such as dimethylformamide and dimethylacetamide; ketones or ketone alcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; polyethylene glycol, polypropylene Polyalkylene glycols such as glycols; ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hex Alkylene glycols having 2 to 6 alkylene groups such as ethylene glycol and diethylene glycol; lower alkyl ethers of polyhydric alcohols such as glycerin, ethylene glycol methyl ether, diethylene glycol methyl (or ethyl) ether, and triethylene glycol monomethyl ether Can be mentioned.

Among these many water-soluble organic solvents, polyhydric alcohols such as diethylene glycol and lower alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl ether and triethylene glycol monoethyl ether are preferable.

Other additives include, for example, pH adjusters, sequestering agents,
Examples thereof include antifungal agents, viscosity modifiers, surface tension modifiers, wetting agents, surfactants, and rust preventives.

The uncoated paper of the present invention was kneaded with an adhesive in which a pigment having a white or various hues described in "March 15, 1964, published by Kogyo Tosho Co., Ltd. Paper Manufacturing" was dissolved and kneaded. Does not include coated paper coated on the surface of the paper. For example, white clay using bleached pulp as described on page 445 of Papermaking Engineering
It means a base paper such as an art base paper which is made by using a Fourdrinier paper machine and is size-pressed by using a sized raw material mixed with about%. The uncoated paper of the present invention may include a size-pressed paper web as described on page 369 of Papermaking Engineering, and the size-pressing liquid may contain a pigment. The fibrous substance used in the present invention is mainly composed of wood pulp, but synthetic pulp, synthetic fiber or the like can be used if necessary.

In the present invention, it is possible to add a filler usually used as a papermaking raw material. As the filler, clay, talc and the like commonly used, heavy calcium carbonate, light calcium carbonate, kaolin, calcined kaolin, aluminum oxide, aluminum hydroxide, titanium oxide, aluminum silicate, amorphous synthetic silica, and Urea
Formalin resin-based organic pigments and the like.

In the present invention, it is appropriate to use an internally added sizing agent or an externally added sizing agent in order to adjust the Steckigt sizing degree to 10 seconds or more. The internally added sizing agent is a rosin acid soap and its derivatives, which are usually used in acidic papermaking systems, rosin emulsion type sizing agents, wax emulsions, petroleum resin sizing agents, etc., and higher organic ketene dihydrates used in neutral papermaking systems. Cellulose-reactive sizing agents such as monomers and substituted cyclic dicarboxylic acid anhydrides, epoxidized higher fatty acid amides, cationized styrene-maleic anhydride copolymers, cationic self-fixing sizing agents such as cationized petroleum resins, etc. pulp , A filler, and other materials such as a yield improver, a paper strength improver, and a toning agent, which are mixed in a slurry to produce a paper, thereby exhibiting size properties. The externally added sizing agent is styrene-
Acrylic acid copolymer, styrene-maleic acid copolymer, α-olefin-maleic anhydride copolymer, petroleum resin-based, alkyl ketene dimer-based, equal size press machine, gate roll coater, etc. exhibit size properties by adhering to paper surface Say what to do.

These surface sizing agents are usually used oxidized starch, polyvinyl alcohol, CMC, other water-soluble resins and, if necessary, heavy calcium carbonate, light calcium carbonate, clay talc, synthetic silica, pigments such as titanium oxide, and other dispersions. It can also be used together with agents, toning agents, defoaming agents and the like.
The paper produced in this manner so as to have a Steckigt sizing degree of 10 seconds or more is normally made into a high-quality paper with a Beck smoothness of about 20 seconds to 80 seconds through a machine calendar. However, when used for inkjet recording paper, these high-quality papers with a Steckigt sizing degree of 10 seconds or more and a Beck smoothness of 100 seconds or less have jagged edges around the dots, and the ink droplets with high absorption and uneven density The image is distorted and looks messy because it does not form sharp dots when hit. Further, when the Steckigt sizing degree is 10 seconds or less, the absorbability is improved but the bleeding rate of the dots is increased, so that it is unsuitable as an inkjet paper requiring high resolution.

In the present invention, the Steckigt sizing degree is thus determined.
It is necessary to adjust the Beck's smoothness to 100 seconds or more and 600 seconds or less, preferably 120 seconds or more and 500 seconds or less by passing the paper manufactured for 10 seconds or more through the nip of the super calendar roll.

By doing so, it becomes a surface that is well compatible with the ink, and it is possible to obtain an ink jet paper that has a high absorptivity and uniform dot shapes and high resolution.

If the Beck's smoothness is 100 seconds or less, the absorptivity, the resolution, etc. are lowered as described above.

If the Bekk smoothness is 600 seconds or more, the fibers will be crushed too much, the absorption capacity will decrease, the dot shape will also become non-uniform, and the paper will become weak and difficult to handle, making it unsuitable as an inkjet paper. Is.

The dot diameter used in the present invention is Canon Inc.
The area of a single dot printed with black ink using an inkjet printer manufactured by A-1210 was measured with a halftone dot area meter (Viewback manufactured by Toyo Ink Mfg. Co., Ltd.) and corrected to an area assumed to be a perfect circle. Then, the value calculated as the diameter was used. It can be said that the smaller the dot diameter, the better the resolution.

Absorption capacity is polyethylene glycol (PEG No. 40
0) / water is used 1/1 solution at 20 ℃ for 10 seconds to contact the ink receiving surface of a certain area, remove the excess liquid with blotter paper,
It is the value obtained by measuring the weight of the solution absorbed on the ink receiving surface in 10 seconds with a precision balance and converting it into the weight per square meter. The contact angle was measured by measuring the contact angle between the small droplet of pure water at 20 ° C. and the ink receiving surface after 10 seconds. With regard to image quality, the goodness of an image was judged by the density unevenness of a solid printed portion of black ink of the same printer. Beck's smoothness and Steckigt's size were measured according to JIS-P8119 and J.IS-P8122, respectively.

(E) Examples Examples of the present invention will be described below, but the invention is not limited to these examples. The parts and% in the examples mean parts by weight and% by weight.

Examples 1 to 5 LBKP (hardwood bleached kraft pulp) with a freeness of 380 ml csf 80
Parts, 20 parts of NBKP (softwood bleached kraft pulp) with a freeness of 410 ml csf, 10 parts of internal filling talc, 2 parts of internal filling clay, 0.3 parts of rosin sizing agent and 2.2 parts of band Paper was made with a net paper machine, and oxidized starch was adhered at a solid content of 2.6 g / m ² by a size press machine, and a base paper with a basis weight of 87 g / m ² was produced through a machine calendar. The Stoeckigt sizing degree of this base paper was 58 seconds, and the Beck smoothness was 38 seconds on the front side. Beck's smoothness of 118 s, 228 s, 332 s, and 483 s
Seconds, 556 seconds were used as the recording sheets of Examples 1, 2, 3, 4, and 5. The Steckigt sizing degree is 51 seconds, 48 seconds, 43, respectively
Seconds, 37 seconds, 40 seconds. Table 1 shows the evaluation results of these recording sheets.

Comparative Example 1 The base papers of Examples 1 to 5 described above were used as recording sheets as they were, and Comparative Example 1 was obtained.

Comparative Example 2 A recording paper having a Beck smoothness of 256 seconds was obtained through a super calender, except that the rosin sizing agent was added in an amount of 0.1 part among the base paper production formulations of Examples 1 to 5 described above. . This recording paper has a Steckigt size degree of 3.5
Since it was second, it was set as Comparative Example 2.

Example 6 80 parts LBKP having a freeness of 370 ml csf, NBKP20 having a freeness of 415 ml csf
Parts, 7 parts of heavy calcium carbonate, 3 parts of talc for internal addition, 1 part of cationic starch, 0.07 parts of alkyl ketene dimer sizing agent and 0.4 parts of polyalkylene polyamine epichlorohydrin resin are added to a Fourdrinier paper machine. Papermaking was performed by using a size press machine, and polyvinyl alcohol was adhered so that the solid content was 2,4 g / m ^2, and the raw paper having a basis weight of 68 g / m ² was manufactured through a machine calendar. The base paper had a Steckigt sizing degree of 12 seconds and a Beck's smoothness of 29 seconds. The base paper was supercalendered to obtain a paper having a Beck's smoothness of 183 seconds and a Steckigt's size of 11 seconds, which was used as a recording paper of Example 6.

The results of evaluation of this recording paper are shown in Table 1.

Comparative Example 3 The comparative example 3 was prepared by lightening the super calendering process on the base paper of Example 6 and setting the Bekk smoothness to 83 seconds.
This product had a Steckigt sizing degree of 12 seconds.

Comparative Example 4 When the base paper of Example 6 was strongly supercalendered, the Bekk smoothness was 631 seconds and the size was 9.2 seconds. This was used as the recording paper of Comparative Example 4.

Example 7 The base paper of Example 6 was manufactured in exactly the same manner as the size press liquid, except that 2% of polyvinyl alcohol and 3% of a surface sizing agent (Coropearl M-150 manufactured by Hoshi Kogaku KK) were used. I got the base paper. The base paper had a Steckigt sizing degree of 23 seconds and a Beck smoothness of 67 seconds. Super calendering this base paper and Beck smoothness of 378 seconds,
A sheet having a Steckigt size degree of 20.8 seconds was obtained and used as a recording sheet of Example 7. The results of evaluation of this recording paper are shown in Table 1.

Comparative Example 5 The recording sheet of Comparative Example 5 was obtained by subjecting the sheet of Comparative Example 7 to supercalendering to obtain a sheet having Beck's smoothness of 672 seconds and Steckigt's size of 19.2 seconds.

The results of evaluation of this recording paper are shown in Table 1.

[Evaluation Criteria] ⊚: Good with little uneven density.

◯: Density unevenness is slight and within the allowable range.

Δ: There is considerable density unevenness, which is outside the allowable range.

X: There are many density irregularities and it is out of the allowable range.

From Table 1, the evaluation results of Examples 1 to 7 and Comparative Examples 1 to 5 are:
It is as follows.

In Examples 1 to 7, both the Steckigt sizing degree and the Beck's smoothness are within the scope of the present invention, the absorption capacity and the dot diameter are appropriate values, the imageability is good, and the density unevenness is small or slight. .

In Comparative Example 1, both the Steckigt sizing degree and the Beck's smoothness are outside the scope of the present invention, the absorption capacity is small, the image quality is poor, and the density unevenness is considerable.

In Comparative Example 2, the Steckigt sizing degree is out of the range of the present invention, and since the absorption capacity is large, the dot diameter is large. For this reason, the image quality is poor and there is considerable density unevenness.

In Comparative Example 3, the Beck's smoothness is outside the lower limit of the present invention, the absorption capacity is small, the image quality is poor, and the density unevenness is large.

In Comparative Example 4, the Steckigt sizing degree is outside the lower limit range of the present invention, the Beck smoothness is outside the upper limit range of the present invention, and the absorption capacity is large, so the dot diameter is large. Therefore, the image quality is poor and there are many density irregularities.

In Comparative Example 5, the Beck smoothness is outside the upper limit range of the present invention, and the absorption capacity is large, so the dot diameter is large. For this reason, the image quality is poor and there is considerable density unevenness.

As described above, in each of the examples within the scope of the present invention, obviously satisfactory results are obtained. On the other hand, in the comparative example, a satisfactory result is not obtained because it is out of the range of the present invention.

(F) Effects of the invention As is clear from Table 1, Examples 1 to 1 in which the Steckigt sizing degree is 10 seconds or more and the Beck smoothness is 100 seconds or more and 600 seconds or less
In No. 7, it is clear that the dot diameter associated with the resolution is small and good, and the absorption capacity is also good, and the overall image quality as inkjet suitability is excellent.

Claims (1)

[Claims] 1. An inkjet recording paper for recording by ejecting and flying a recording liquid from an orifice, wherein the recording paper has a Steckigt sizing degree of 10 seconds or more and a Bekk smoothness of 100 seconds to 600 seconds. Ink jet recording paper made of uncoated paper, characterized in that