JP3115171B2 - Recording paper and image forming method using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording paper, and more particularly, to a so-called plain paper type which can be used in both an ink jet recording apparatus and an electrophotographic recording apparatus and has no special coating on the recording surface. Recording paper and an image forming method using the recording paper.

[0002]

2. Description of the Related Art An ink jet recording system is a system in which ink is directly ejected onto a recording sheet, and has attracted attention as a recording method which is lower in running cost than conventional recording apparatuses, quiet and easy in color recording. As the ink used in such a recording method, a water-based ink is used in terms of safety and printing characteristics, and the recording material absorbs the ink quickly to the recording material, and there is an overlap of different color inks. Even if the ink does not overflow, the spread of the ink dots is appropriate, and the dot shape is close to a perfect circle, and the dot edges are sharp. Naturally, the dot density is high. In addition, it is required that the whiteness is sufficiently high to make the dot contrast stand out.

Conventionally, in order to meet such a demand, use of a dedicated coated paper as disclosed in JP-A-1-135682 has been proposed. On the other hand, in the field of monochrome recording and business recording, even low-priced and versatile recording paper, that is, plain paper generally used in the field of electrophotographic recording can be used for the ink jet recording. Is desired.

However, when the plain paper for the electrophotographic recording system is used for the ink jet recording system, the ink absorbency is poor, and when a large amount of ink is applied, the ink overflows. In addition, since the ink is absorbed along the fibers of the paper, inconveniences such as a blurred shape of the ink dot occur. Further, in recent years, the mainstream of the plain paper for the electrophotographic recording system has been shifting from acidic paper to neutral paper due to the demand for the preservability of the paper. In the case of these papers, there is a problem that the black ink used in the ink jet recording system causes a browning phenomenon of an image called bronze.

As a means for solving these problems, the present applicant has reduced the amount of high-boiling organic solvent previously contained in the ink for the purpose of preventing clogging due to drying of the recording nozzles, while reducing the amount of the ink. An ink-jet recording method using ammonia, urea and its derivatives, amino alcohol, alkylamine, amino acid and the like as a dissolution aid and using the ink internally added to paper to be recorded using this ink has been proposed.

[0006]

However, even if the properties as the ink jet recording paper are sufficiently imparted as described above, the plain paper for the electrophotographic recording system is usually manufactured using a high-speed paper making machine. A distribution occurs in the thickness in the plane of the paper, causing unevenness in ink absorbency,
In particular, there is a problem that the density unevenness appears when a solid image is formed. In order to solve this problem, it is necessary to perform a calendering process after the production of the paper to adjust the thickness of the paper.

However, if the paper thickness is simply made uniform by calendering, the paper density becomes too high.
In addition to inhibiting ink absorption, the coefficient of friction between paper and paper may be too high, causing the phenomenon of so-called double feed, which is sent in an overlapping manner when used in an electrophotographic recording device, etc. There is.

Accordingly, an object of the present invention is to provide a so-called plain paper type recording sheet which can be used in both an ink jet recording apparatus and an electrophotographic recording apparatus, and in particular, has no special coating on the recording surface. An object of the present invention is to provide an image forming method using paper.

[0009]

The above objects are achieved by the present invention described below. That is, the present invention relates to a recording paper based on a neutral paper prescription, wherein one thin portion of the recording paper has
cm ² , the diameter of the portion converted to a circle is 0.5 to 2 mm
And the formation change rate is 6% or less and the opacity is 8
A recording sheet characterized by being at least 5%.

[0010]

The present inventors have proposed a recording paper based on a neutral paper prescription, particularly preferably containing a permeation retarder for retarding the permeation of the ink on the recording surface thereof, which is caused by a nitrogen compound in the ink. In the recording paper to which a substance that adsorbs ammonia or ammonium ions is added, the thickness of the recording paper in the plane is made uniform over a certain area or more, and the surface smoothness is adjusted appropriately to achieve the present invention. The goal was achieved.

More specifically, the in-plane thickness of the recording paper, which is generally referred to as formation, can be measured by a formation meter using a laser beam. From the number distribution, the formation change rate, which is an indicator of the formation of the recording paper, can be integrated, and it is possible to indicate what percentage of the unit area of the recording paper corresponds to the thin part. Is obtained by dividing the standard deviation of the total transmittance of the recording paper measured by the total average transmittance with respect to the total transmittance. When this index is used, the formation change rate is about 6% or less, preferably 4.5% or less. When the ink jet recording, which is an effect of the present invention, is performed over the entire surface of the recording paper, the density becomes a level at which almost no density unevenness is felt.

Further, in order to achieve uniform transfer of the toner for electrophotographic recording caused by irregularities of the fibers of the recording paper, the surface roughness of the recording paper is adjusted by a calendar part shown in FIG.
J. TAPPI No. The surface smoothness measured by the 5B method is 80 seconds or more, and preferably 95 seconds or more. In order to ensure the stability of feeding the recording sheet to the recording apparatus, the variation in the coefficient of friction between recording sheets is suppressed. For purposes, a maximum of 200 seconds or less, preferably 160 seconds or less, is the most desirable form.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described in more detail with reference to preferred embodiments. The recording paper of the present invention is LB
Paper is made by a conventional method mainly using chemical pulp represented by KP and NBKP, a sizing agent and a filler, and other papermaking aids as required. As the pulp material to be used, recycled paper pulp may be used, and there is no problem even if it is used as a main material.

As sizing agents, rosin size, AK
D, Alnikel succinic anhydride, petroleum resin size, epichlorohydrin, cationic starch, acrylamide and the like. However, when the recording paper used in the electrophotographic recording apparatus is a sheet having a small surface free tension of the sizing agent, the fixing property of the toner resin used in the recording apparatus may be impaired. What is necessary is just to select suitably according to a toner.

The recording paper of the present invention is adjusted to have a water extraction pH of 6 or more, preferably 7 or more. The water extraction pH is a value obtained by measuring the pH of an extract obtained by immersing about 1.0 g of a test piece specified in JIS-P-8133 in 7 ml of distilled water in accordance with JIS-Z-8802. p
When H is less than the above range, not only does the long-term storability of the recording paper itself deteriorate, but also the dye in the ink does not show sufficient coloring properties.

If the recording paper size adjusted in this manner is too low, the attached ink droplets are too bleeding, and it is difficult to form clear images and characters, and if it is too high, the ink will last long. Is not absorbed into the recording paper layer, so that the attached ink has poor drying properties. For this reason, it is preferable that the Steigcht sizing degree is in the range of 16 to 40 seconds.

In the present invention, the recording surface of the recording paper preferably contains an ink penetration retarder. In this case, the ink adhering to the recording surface of the recording paper of the present invention is delayed from penetrating into the recording paper layer by about 0.01 seconds to several seconds due to the action of the permeation retarder, and water on the recording surface of the recording paper is After evaporating most of the low-boiling solvents such as, it penetrates into the recording paper layer. By this effect, the ink does not bleed more than necessary, and the dye stays near the recording surface, so that a dot with high contrast is formed.

Preferred materials for the penetration retardant include:
For example, cellulose derivatives such as casein, starch, carboxymethylcellulose, and hydroxyethylcellulose, polyvinyl alcohol, polyvinylpyrrolidone, sodium polyacrylate, polyacrylamide, etc., hydrophilic resins swellable to ink, SBR latex, acrylic emulsion, styrene / Maleic acid copolymer,
Water-repellent substances such as resins having a hydrophilic part and a hydrophobic part in the molecule, such as styrene / acrylic acid copolymer, silicone oil, paraffin, wax, and fluorine compound;
And the aforementioned sizing agents. These materials are
About 0.1 to 3 g / m ² is applied to the recording surface. Within the above range, the effect of delaying ink penetration is maintained,
Further, the ink, which is the residual evaporation containing a non-volatile solvent such as polyhydric alcohol, penetrates and is absorbed in the recording paper layer, so that the ink fixing property does not extremely deteriorate.

The recording paper of the present invention preferably contains a recording paper layer in which a substance that adsorbs ammonia or ammonium ions generated from a nitrogen compound in the ink used for ink jet recording is added. Such materials include, for example, fillers such as finely divided silica, aluminum silicate, diatomaceous earth, kaolin, kaolinite, halloysite, nacrite, dickite, pyrophyllite, sericite, titanium dioxide, bentonite, activated clay, acrylic acid or Homopolymers of monomers such as methacrylic acid or copolymers with other general monomers, homopolymers of α, β unsaturated acids such as maleic acid and methacrylic acid or copolymers with other general monomers , A polymer having a sulfonic acid group, an ester of a polyvalent carboxylic acid and a polyhydric alcohol, an acidic cellulose derivative modified with a polyvalent carboxylic acid or a polymer such as sodium, potassium or the like, or an alkali metal salt thereof; sodium lauryl sulfate; Sodium cetyl sulfate, sodium polyoxyethylene lauryl ether sulfate, Surfactants such as sodium uryl phosphate, sodium polyoxyethylene lauryl ether phosphate, salts such as alkylbenzenesulfonic acid and alkylsulfosuccinic acid, and the like.

In general, in ink jet recording, the edges are sharp and uniform, the ink has an appropriate ink bleeding on the recording paper surface, and high density dots are formed (to form a high quality image). As a configuration of both the ink and the recording paper, the ink droplets adhering to the recording surface are not instantaneously absorbed into the recording paper layer, and after the evaporation of the ink solvent on the recording paper surface is completed to some extent, Desirably, it is absorbed in the recording paper layer.

On the other hand, according to the knowledge of the present inventors, the above-mentioned bronze aggregates in a form in which a part of the dye in the ink is oriented, is not absorbed in the recording paper layer, and is folded on the recording paper surface. This is a phenomenon in which the black print portion appears brownish.
Therefore, improving the print quality by the above method and suppressing the generation of bronze are contradictory problems. Further, this problem is remarkable in a printed image using an ink containing a nitrogen compound. This is because ammonia or ammonium ions generated from nitrogen compounds promote the orientation or aggregation of the dye in the process of evaporating the solvent on the recording paper surface,
This is considered to accelerate the deposition of the dye from the remaining ink solvent. It is presumed that the reason why bronze is remarkable is neutral paper having a water extraction pH of 7 or more.

In the recording paper of the present invention, when a substance which adsorbs ammonia and ammonium ions generated from a nitrogen compound in the ink is internally added, particularly in an ink jet recording method using an ink containing a nitrogen compound and neutral paper. An ink jet recorded image with good print quality and no bronzing is provided while maintaining the advantages. Further, the recording paper of the present invention does not involve a significant change in the surface shape and physical characteristics other than the recording characteristics even when compared with the conventional neutral PPC paper. It is applicable to both.

As described above, the ink used in the ink jet recording method of the present invention contains water as a main component, an organic solvent such as a polyhydric alcohol, a dye as a recording agent, a nitrogen compound as a dye dissolution aid, The composition further contains other additives as necessary. As the dye itself used for the ink, a conventionally known acid dye or direct dye can be used, and particularly preferred are the following black dyes.

[0024]

Embedded image

[0025]

Embedded image (However, in the above formula, M is Na or Li, R is H or an alkyl group, X _{1 to} X ₅ are H, SO ₃ Y ₁ or COOY ₂ ,
Y ₁ and Y ₂ are Na, Li, K or NH ₄ . )

As an ink jet recording system which can use the recording paper of the present invention, there is a conventionally known ink jet recording system in which small droplets of ink are ejected from nozzles and recording is performed using various driving principles. It can be applied to any of them. Among them, the present invention is disclosed in
According to the method disclosed in Japanese Patent Application Laid-Open No. 4-59936, the ink that has been subjected to the action of thermal energy causes a sudden change in volume, and the ink can be particularly effectively used in an ink jet system in which the ink is ejected from a nozzle by the action force due to this state change.

The electrophotographic recording system using the recording paper of the present invention is well known, and an example of the apparatus is shown in FIGS. 2 and 3. FIG. As shown in FIG. 2, a photoreceptor 3 having photoconductive properties is charged by a primary charger 5 and then exposed to form an electrostatic latent image. After the electrostatic latent image is developed using the toner 8 of the developer in the two-component developer to form a toner image,
The toner image on the photoreceptor is transferred to the recording paper 4 of the present invention, which is separately conveyed, by a transfer charger 7 as a transfer unit. Subsequently, as described above, the image is transferred by a fixing device 12 as a fixing unit including two rollers 9 and a roller 10 (or one roller and one belt) shown in FIG. 2 by the action of heat, pressure, or both. The obtained toner image is fixed on the recording paper 4 to obtain a final copied image.

Recording paper 4 generated in the transfer step
The unfixed toner and paper dust generated from the recording paper 4
Removed by the cleaner unit 1 arranged in the transfer process,
The photoconductor 3 is cleaned. After the surface of the photoconductor is cleaned by the cleaning member 2 (for example, a cleaning blade) in contact with the photoconductor 3, a process such as charging is repeated again. Further, as shown in FIG. 2, unfixed toner and paper dust generated from the recording paper 4 in the fixing device 12 are removed by the cleaning member 11 abutted on the fixing roller 9.
And a release agent such as silicone oil is applied to the fixing roller 9. The above-described example describes one example of a method of forming an image using the recording paper of the present invention in an electrophotographic recording system, and the recording paper of the present invention may be any other known electrophotographic recording apparatus. Of course, it can also be used.

Next, the most characteristic feature of the recording paper of the present invention will be described. Regarding the paper formation, the shape, size, number, etc., of the portion where the paper thickness fluctuates differ depending on the type of paper making machine, but as described above, the paper density is low and the paper thickness is thin. If the formation variation rate of the entire paper surface is 6% or less, almost the desired uniform image can be obtained. However, depending on the papermaking conditions, the extremely thin portion is the resolution level of human eyes of 0.5 to 2 mm. (Circular conversion). In this case, even if the formation variation rate is 6% or less, since the density difference of the printed image is conspicuous, the number of formations is limited, and the vibration of the wire in the paper making machine is reduced to less than 1 piece / cm ² . It is necessary to adjust the dehydration speed and the like.

Further, in the case of manufacturing with a usual fourdrinier machine, the speed of the wire is reduced to 300 m / sec or less to improve the formation, because the dewatering speed needs to be apparently increased. The formation obtained in this case is a recording paper having a diameter exceeding 10 mm. Further, it is necessary to set the papermaking conditions so as to prevent the formation portion from being extremely thin as described above.

As described above, there is a method of increasing the transparency of the recording paper for the purpose of improving the appearance without depending on the production conditions of the papermaking machine. In this method, however, the surface smoothness of the recording paper which is the object of the present invention is used. The ink density cannot be achieved, resulting in uneven density of the ink. Furthermore, by increasing the transparency of the paper, show-through will occur,
The quality as a color image is significantly reduced. In view of these circumstances, the recording paper required in the present invention is J
The opacity according to IS-P8138 is 85%, preferably 90% or more, and at such opacity level,
The above-mentioned formation change rate can be achieved.

In particular, when used in an electrophotographic recording apparatus, if the difference between the thickness of the formation portion of the recording paper and the non-forming portion is 15 μm or more, a remarkable difference occurs in the transferability of the solid image, and the density of the formation portion is reduced. Will decrease. In order to prevent this, it is necessary to adjust the thickness of the recording paper by calendering, and as a guide, a surface smoothness of 80 seconds or more, preferably 95 seconds or more is preferable in terms of transferability of an electrophotographic recorded image. .

However, when the recording paper having a basis weight of less than 75 g / m ² is finished to have a surface smoothness of more than 160 seconds, a problem of double feeding occurs when the recording paper is fed in the electrophotographic recording apparatus. . In addition, the grammage is 75 g
/ M ^{2 to} 210 g / m ² ,
A similar phenomenon may occur when a surface smoothness exceeding 0 seconds is applied to recording paper. In addition, 200
If the recording paper is finished to have a surface smoothness exceeding seconds, the density of the paper will be too high, which will significantly impair the ink absorbency. Further, when increasing the surface smoothness of the recording paper, it is a simple method to increase the water content of the ordinary recording paper to 6% or more, but an electrophotographic recording apparatus, an ink jet recording apparatus and the like are used for recording. It is rare that the paper is used in an environment having a balanced water content at the time of paper making, and it is preferable to make the paper with a water content of 4 to 5% by weight in order to suppress the behavior due to the environmental difference of the recording paper itself.

[0034]

Next, the present invention will be described more specifically with reference to examples and comparative examples. In the following, “parts” or “%” is based on weight unless otherwise specified. Example 1 After 100 parts of raw material pulp LBKP was beaten, 10 parts of kaolin, 0.2 parts of alkenyl succinic anhydride and 0.5 parts of cationized starch were blended, and the mixture was mixed with a conventional fourdrinier machine shown in FIG. Paper-made. The speed during papermaking was 200 m / m.
and the dewatering conditions were the same as those at 500 m / min to obtain paper having a basis weight of 73 g / m ² and a Steckigt sizing degree of 23 seconds. The formation change rate of the obtained paper is 3.
8%, the size of one formation was an average diameter of 15 mm in terms of a circle, and the thickness difference was about 17 μm. An aqueous solution of a permeation retardant consisting of 95 parts of oxidized starch and 5 parts of a styrene / maleic acid copolymer was prepared, applied at 1 g / m ² in a size press step, and further subjected to a calendaring step to give a surface smoothness of 95 seconds. The recording paper A of the present invention was obtained by adjusting the pressure so that The formation thickness difference of the obtained recording paper A is about 7
μm. The opacity was 86%.

Comparative Example 1 Example 1 was repeated except that the papermaking speed was 400 m / min.
Under the same conditions as above, a recording paper B of a comparative example was obtained. The formation fluctuation rate of the obtained recording paper was 7.5%. The size of one formation was an average diameter of 10 mm in terms of a circle, and the thickness difference was 13 μm. The opacity was 88%.

Example 2 The same procedure as in Example 1 was carried out except that the dewatering was performed at a speed of 400 m / min in accordance with the papermaking conditions at a speed of 800 m / min when the dewatering was performed in the wire part of the papermaking machine shown in FIG. Recording paper C of the present invention was obtained with the same prescription as that of Example 1. The formation variation rate of the obtained recording paper was 4.2%, the size of one formation was 1.5 mm in terms of a circle, and the surface smoothness was 102.
Seconds. The opacity was 89%.

Comparative Example 2 Under the same conditions as the dehydration speed of 250 m / min,
Papermaking was performed under the same conditions as in Example 1 except that the surface smoothness was reduced to 60 seconds by lowering the pressure in the calendar part of the papermaking machine shown in FIG. The formation variation rate of the obtained recording paper D was 6.5%, the size of one formation was an average diameter of 3 mm in terms of a circle, and the thickness difference at the formation was 22 μm. The opacity was 90%.

Example 3 The same formulation as in Example 1 was used except that 100 parts of the aqueous solution of the permeation retardant AKD and 0.2 part of polyoxyethylene lauryl sulfate ether were used. Increasing the amount of raw materials discharged, the grammage of 85 g /
to obtain a paper m ^2. The area ratio and size of the formation of this paper were the same as those of the recording paper A, and the difference in formation thickness was 23 μm. Next, the paper was smoothed by the calendar part shown in FIG. 1, the surface smoothness was set to 120 seconds, and the formation thickness difference was 8 μm.
The recording paper E of the present invention was obtained. The opacity is 92
%Met.

Comparative Example 3 A recording paper F of Comparative Example 3 was obtained under the same conditions as in Example 3 except that the pressure in the calendar part of the paper making machine shown in FIG. 1 was increased to make the surface smoothness 205 seconds. The difference in formation thickness of the obtained recording paper was 2 μm. The opacity was 86%. Comparative Example 4 Comparative Example 2 was the same as Comparative Example 2 except that alkenyl succinic anhydride was changed to AKD, kaolin was changed to calcium carbonate, and the composition of the coating solution was changed to only 100 parts of starch. Similarly, recording paper G was obtained. In the obtained recording paper G, the opacity was reduced to 81% and the formation change rate was 4.1% because kaolin was changed to calcium carbonate.

Evaluation Evaluation by Electrophotographic Recording Apparatus Each of the recording papers A to G obtained in the above Examples and Comparative Examples was used as an electrophotographic recording apparatus by a Canon copier NP9.
Image formation was performed using a CLC500 and CLC500, and the following evaluations were made. Table 1 shows the evaluation results. Evaluation Items (1) Transfer Unevenness The value measured by a Macbeth densitometer was 0.
A solid color solid image mark adjusted to 6 was made. In the obtained solid images, those having unevenness as a portion where the image density was visually lower than the peripheral part were visually evaluated as x, and those without unevenness were evaluated as o without unevenness. (2) Gasatsuki Adjusted so that the density measured with a Macbeth densitometer became 0.6, and formed a light-colored magenta image. In this halftone image, 200 image lines were disturbed, and those that could be recognized as white points were marked as x, those that looked like color bleeding were rated as △, and those without white spots and roughness were rated as ○. (3) Image show-through A solid image of magenta, cyan, and yellow is formed so that the density measured by the Macbeth densitometer becomes 0.6, and this image is observed from the back side, and a case where color identification is possible. ×, when impossible, was rated as ○.

Evaluation by Inkjet Recording Apparatus An ink having the following composition for evaluation was prepared. (Ink composition) Ink a: Dye (a mixture of the compounds of the specific examples of the ink described above, but the counter ion is Li for and Li is Na) 3 parts Diethylene glycol 5 parts Ethanol 5 parts Urea 5 parts 82 parts of water Ink b: The same as ink a except that only the dye of a was replaced.

Ink c: The same as ink a except that the dye of the above a was mixed with urea and monoethanolamine was used. Ink d: The same as ink a, except that only the dye of the above a was replaced.

Recording papers A to G so that the combinations shown in Table 1 are obtained.
Using inks a to d, recording is performed by an inkjet recording apparatus equipped with an inkjet recording head that has recording nozzles at a rate of 14 nozzles per 1 mm and ejects ink droplets by the action of heat, thereby improving recording suitability. evaluated. Table 1 shows the results.

Evaluation Items (1) Printing Quality A straight line having a width of 1 dot was printed in parallel with the scanning direction of the head.
The evaluation was made visually from a distance of 25 cm. When the edge of the straight line was opaque and blurred, or when feathering was conspicuous, the result was evaluated as x.

(2) Bronze Solid printing was performed on the entire surface of the recording paper using the above-described recording apparatus.
When the printed portion was recognizable as black, it was rated as ○, and when bronze was generated and a brown magenta pattern was seen, it was rated as x. Table 1 shows the evaluation results.

[0046]

[Table 1]

[0047]

According to the present invention, as described above, according to the present invention, neutral plain paper for both ink jet recording and electrophotographic recording, which can obtain a uniform image without ink absorption unevenness and toner transfer unevenness, and The image forming method used can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a configuration of a general paper making machine used in Examples and Comparative Examples.

FIG. 2 is a diagram illustrating copying by an electrophotographic recording method.

FIG. 3 is a diagram illustrating a fixing process in the electrophotographic recording method.

[Explanation of symbols]

 1: Cleaner part 2: Cleaning member 3: Photoconductor 4: Recording paper 5: Primary charger 6: Developing device 7: Transfer charger 8: Toner 9, 10: Roller 11: Cleaning member 12: Fixing device

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Mamoru Sakaki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Masato Katayama 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inside (72) Inventor Akio Suzuki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Yoshihiro Takada 3-30-2, Shimomaruko 3-chome, Ota-ku, Tokyo Inside Canon Inc. ( 56) References JP-A-58-176641 (JP, A) JP-A-62-162585 (JP, A) JP-A-63-113471 (JP, A) JP-A-62-140877 (JP, A) JP-A-2-167772 (JP, A) JP-A-6-8617 (JP, A) JP-A-6-183136 (JP, A) JP-A-6-220794 (JP, A) Patent 2899189 (JP, B2) ( 58) Surveyed fields (Int. Cl. ⁷ , (DB name) B41M 5/00 G03G 7/00

Claims (7)

(57) [Claims] 1. A recording paper based on a neutral paper prescription, wherein a portion having a thin formation is less than 1 piece / cm ^2.
The diameter converted to a circle is 0.5 to 2 mm and the formation change rate is 6
% Or less, and the opacity is 85% or more. 2. The recording sheet according to claim 1, wherein the formation change rate is 4.5% or less. 3. The recording sheet according to claim 1, wherein the surface smoothness is 80 seconds or more and 200 seconds or less. 4. A recording sheet according according to any one of claims 1 to 3 applied to an image formation by an electrophotographic recording system. 5. A recording medium having a permeation retarder for retarding permeation of a liquid ink containing a nitrogen compound, and a component for adsorbing ammonia or ammonium ions generated by the nitrogen compound in the ink. to be, recording sheet according according to any one of claims 1 to 3 applied to an image formation by an ink-jet recording system. The recording paper according to any one of 6. The method of claim 1 to 4, the toner image formed on the photosensitive member is transferred electrostatically, the toner image transferred onto the recording sheet Wherein an image is fixed by applying heat and / or pressure to form a recorded image. 7. the recording paper according to any one of claims 1 to 4, be deposited by discharging from an orifice of a recording head with a small drop of the liquid ink containing a nitrogen compound in accordance with recording signals Forming an image on the recording sheet by using an inkjet recording method.