JP2006297780A - Inkjet recording paper and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording paper having truely excellent gloss and its manufacturing method. <P>SOLUTION: This recording paper comprises an ink accepting layer, on which a glossy layer is provided, on a base paper, wherein the smoothness under being pressurized with the pressure of 20 kg/cm<SP>2</SP>by microphotograph of the surface of the ink accepting layer is Rp=1.0-5.0 μm and that of the surface of the glossy layer is Rp≤2.0 μm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an inkjet recording paper having high image clarity and high scratch resistance.

  In recent years, recording by an ink-jet printer has been used in many fields because of low noise, high-speed recording, and easy multi-coloring. As the ink jet recording paper, high-quality paper devised so as to be rich in ink absorbability, coated paper coated with a porous pigment on the surface, and the like are applied. However, since these sheets have low surface gloss, ink jet recording sheets having an excellent appearance have been developed.

  In general, paper with high surface gloss is coated with a plate-like pigment on the surface, and a glossy coated paper with a calender treatment as required, or a wet coating layer is pressed onto the mirror heating drum surface. A so-called cast-coated paper is known which is obtained by drying and copying its mirror surface. This cast-coated paper has a high surface gloss and excellent surface smoothness compared to normal coated paper with a super calender finish, and provides an excellent printing effect. (See, for example, Patent Document 1 and Patent Document 2).

  In Patent Document 1, in an inkjet recording material in which an undercoat layer and an ink receiving layer are laminated on one side of a base paper, the centerline average roughness (Ra1) of the base paper is 1.6 μm or less, and the centerline average of the undercoat layer Roughness (Ra2) is 1.3 [mu] m or less, the difference between Ra1 and Ra2 is 0.5 [mu] m or less, and the 60-degree specular gloss of the recording material surface specified by JIS-Z8741 is 25% or more A recording material is disclosed. The document 1 describes that the ink jet recording material has an effect that the whiteness and gloss of the white paper portion are high.

Patent Document 2 discloses excellent ink jet printing by coating a base coating paper provided with an undercoat coating layer with a casting coating solution containing a polymer having a specific glass transition point, and then finishing the casting. A cast coated paper for ink jet recording which shows recording suitability and maintains high gloss is disclosed, and the blank gloss of the cast coated paper actually produced in the example of the document 2 is in accordance with JIS-P8142. It has been measured.
JP 2003-191616 A JP 7-89220 A

  According to the inventions disclosed in Patent Documents 1 and 2 above, the glossiness of ink jet recording paper is evaluated by a measuring method based on JIS-Z8741 or JIS-P8142. JIS-Z8741 is “specifies a method for measuring the specular gloss of a macroscopically smooth surface of an industrial product”, and JIS-P8142 is “specular gloss at an incident angle of 75 ° of paper and paperboard”. It prescribes how to measure the degree. " For particularly high-gloss paper such as cast-coated paper, measurement is performed using a measuring device with angles of 60 degrees and 20 degrees defined in JIS-Z8741. The specular gloss G is calculated by the following equation (1).

Formula (1)
G = [(reflected light beam from sample surface) / (reflected light beam from standard surface)] x glossiness of standard surface (%) The light flux is the amount of visible light transmitted per unit time. The evaluation is based on the sense of brightness that occurs with respect to the visibility. When the luminous flux is represented by Φ, it is defined by the following equation (2) based on the radiant flux, the standard specific luminous efficiency, and the maximum luminous sensitivity.

Formula (2) Φ = K∫Φ (λ) ・ V (λ) ・ dλ
Here, K is the maximum luminous sensitivity, V (λ) is the standard relative luminous sensitivity, and Φ (λ) is the spectral distribution of the emitted light. When an electromagnetic wave having a wavelength of 380 to 780 nm, which is visible radiation, enters the eye, the sensation of light is generated, but the sensitivity varies depending on the wavelength, and decreases as the distance from the wavelength at which the maximum sensitivity is reached increases. The wavelength with the highest sensitivity is around 555 nm (yellowish green) for photopic vision and near 510 nm (green) for dark vision vision. Compared to the relative visibility of each wavelength based on the visibility at this time, It is called visibility. Thus, the visibility is a wavelength function indicating the relationship between the brightness sensation given by the monochromatic light and the energy of the light, and the specular gloss obtained from the luminous flux calculated based on this visibility is not necessarily the actual glossiness. It does not match the glossiness of appearance.

  As is clear from the above detailed description, it is not appropriate to evaluate the glossiness of an inkjet recording paper by specular glossiness, and an inkjet recording paper evaluated by such an inappropriate evaluation method actually has an excellent gloss. I don't know if I have

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide an ink jet recording paper having a truly excellent gloss and a method for producing the same.

  Therefore, as a result of intensive studies on a method suitable for evaluating the glossiness of inkjet recording paper, the present inventor has found that image clarity is suitable for evaluating the glossiness, and has reached the present invention. .

  The image clarity is defined by JIS-H8866-1, a visual measurement method that is “a method of visually observing the form of a chart scale image projected on a test surface and examining the image clarity”, and JIS-H8866. Defined in 2-2, "A method for obtaining the image clarity by measuring the amount of light by dividing the reflected light from the test surface into regular reflected light and diffused light using an optical comb and moving the reflected light from the test surface by the ratio of the regular reflected light to the total reflected light." There is an instrument measurement method. This image clarity is originally a test method for anodized films of aluminum and aluminum alloys, but the latter instrumental measurement method specified in JIS-H8866-2 provides more objective image clarity data. The present inventor has found that this is preferable as a method for evaluating the glossiness of ink jet recording paper.

  However, when an inkjet recording paper is made with a conventional single-layer uncoated paper and a high-basis base paper as the base paper, the texture and profile of the base paper are different from those of multi-layer paper base and resin-coated base paper. Unfortunately, it is difficult to produce an inkjet recording paper with high image clarity. In addition, there is a means to increase the coating amount of the glossy layer in order to improve image clarity, but the scratch resistance becomes weak, and when the non-coated surface is offset printed, the glossy surface is rubbed and scratched in the printing unit. There is a problem that occurs.

  Therefore, as a result of intensive studies on means for obtaining an inkjet recording paper having high image clarity and high scratch resistance, the present inventors have found that the surface smoothness of the inkjet recording paper having high gloss is the side on which the ink receiving layer is provided and It was found that there was a correlation with the smoothness of the microtopograph on the opposite side, and it was found that the key point was to keep the smoothness of the microtopograph within a specific range.

That is, according to the first invention of the present application, in an ink jet recording paper having an ink receiving layer on a base paper and a gloss layer provided on the ink receiving layer, the surface of the ink receiving layer is pressed under 20 kg / cm ² by microtopography. The smoothness is Rp = 1.0 to 5.0 μm, and the smoothness of the glossy layer surface under a pressure of 20 kg / cm ² by microtopography is Rp = 2.0 μm or less.

Further, according to the second invention of the present application, in the first invention of the present application, the smoothness under a pressure of 20 kg / cm ² by microtopography on the side of the base paper opposite to the surface on which the glossy layer is provided is Rp = 5.0 to 10. It is 0 μm.

  The third invention of the present application is characterized in that, in the first or second invention of the present application, the image clarity of the glossy layer surface measured according to JIS-H8866-2 is 40 (%) or more.

Further, the fourth invention of the present application is a method for producing an ink jet recording paper having an ink receiving layer on a base paper and having a glossy layer provided on the ink receiving layer, wherein the surface of the ink receiving layer is 20 kg / cm by microtopography. ² Smoothness under pressure is Rp = 1.0 to 5.0 μm, and smoothness under pressure of 20 kg / cm ² under pressure of micro topograph on the side of the base paper opposite to the surface on which the glossy layer is provided is Rp = The surface of the base paper opposite to the surface on which the glossy layer is provided and the ink receiving layer are simultaneously subjected to a smoothing process by calendering so as to be 5.0 to 10.0 μm, and then the surface of the glossy layer is microtopographed. The glossy layer is smoothed by a casting method so that the smoothness under a pressure of 20 kg / cm ² is Rp = 2.0 μm or less.

  Since the present invention is configured as described above, it is possible to provide an ink jet recording paper having a truly excellent gloss and a method for producing the same.

  In the ink jet recording paper of the present invention, a gloss layer is provided on a base paper via an ink receiving layer, and specific embodiments will be described in detail.

  Examples of raw materials for the base paper of the inkjet recording paper of the present invention include hardwood kraft pulp, natural pulp, and synthetic pulp. Any natural pulp can be used as long as it is a pulp normally used for papermaking. That is, examples include hardwood bleached kraft pulp, softwood bleached kraft pulp, hardwood unbleached kraft pulp, softwood unbleached kraft pulp, hardwood sulfite pulp, and conifer sulfite pulp. The main raw materials containing wood fibers are mechanically treated pulp and chips that are chemically treated with non-wood fibers such as kenaf, hemp, and straw, which are chemically processed pulps, and non-wood fiber materials. Virgin pulp such as ground pulp, pulp made by mechanically pulping wood or chips with chemicals added, and semi-chemical pulp pulped by refiner after cooking the chips until soft Etc. Moreover, various fibrous materials, such as a synthetic pulp, a synthetic fiber, and an inorganic fiber, can be used as a raw material as needed. In addition, waste paper pulp manufactured using raw newspaper, magazine waste, corrugated waste paper, or the like as a raw material can also be blended.

  The base paper of the ink jet recording paper of the present invention can be produced by making paper using the above raw materials. Papermaking can be performed using, for example, a paper machine such as a long paper machine, a twin wire paper machine, an on-top paper machine, a hybrid paper machine, or a round paper machine. When making paper, additives commonly used in producing ink jet recording paper can be added to the pulp. Examples of such additives include polyacrylamide, polyvinyl alcohol polymer compounds, urea resin, melamine resin, starch and other paper strength enhancers: chemical fixing agents such as sulfuric acid bands: polyacrylamide, acrylamide-aminomethylacrylamide Freeness or yield improver such as copolymer salt, cationized starch, polyethyleneimine, polyethylene oxide, acrylamide-sodium acrylate copolymer: rosin size, alkyl ketene dimer (AKD), alkenyl succinic anhydride ( Examples include sizing agents such as ASA): waterproofing agents such as polyamide, polyamine, and epichlorohydrin: antifoaming agents, fillers such as talc, etc .: dyes: color pigments: antibacterial agents: ultraviolet absorbers: pH adjusting agents, and the like.

The ink receiving layer of the ink jet recording paper of the present invention is a layer for absorbing and drying ink, and contains a pigment. As pigments, amorphous silica, alumina, clay, calcium carbonate, kaolin, talc, magnesium carbonate, barium persulfate, aluminum silicate, magnesium silicate, colloidal silica, composite of alumina and silica, zeolite, diatomaceous earth, magnesium hydroxide , Hydroxyapatite, mica, titanium dioxide, zinc oxide, lead titanate and the like. Among these, from the viewpoint of improving ink absorbability, those containing amorphous silica as a main component are preferable. The pigment preferably has an average particle diameter of 0.01 to 9.0 μm, more preferably 0.01 to 8.0 μm. The BET specific surface area is preferably 100 to 400 m ² / g, and more preferably 100 to 300 m ² / g. The above pigments may be used alone or in combination of two or more.

  As the pigment used in the gloss layer, inorganic fine particles having an average primary particle diameter of 100 nm or less are used in terms of gloss and transparency. For example, synthetic silica, alumina, alumina hydrate, calcium carbonate, magnesium carbonate, magnesium chloride, titanium dioxide, zeolite and the like can be used. Preferably, at least one of gas phase method silica, colloidal silica, alumina, and alumina hydrate is used.

  The ink receiving layer and the glossy layer preferably contain a binder. Examples of such a binder include polyvinyl alcohol, vinyl acetate, styrene-butadiene copolymer, polyvinyl acetal, oxidized starch, etherified starch, Carboxymethylcellulose, hydroxyethylcellulose, casein, gelatin, soybean protein, polyethyleneimide resin, polyvinylhydrin resin, polyacrylic acid or copolymer thereof, maleic anhydride copolymer, acrylamide resin, acrylate resin, Polyamide resin, polyurethane resin, polyester resin, polyvinyl butyral resin, alkyd resin, epoxy resin, epichlorohydrin resin, urea resin, melamine resin, methyl methacrylate-butadiene copolymer Acrylic polymer latex such as polymer, acrylate ester, methacrylic acid ester polymer or copolymer, resin of vinyl polymer latex such as ethylene-vinyl acetate copolymer, etc. . The said binder may be used independently and may mix and use 2 or more types.

  The outermost layer of the ink jet recording paper of the present invention is a glossy layer. As a method for forming the gloss layer, strong gloss can be imparted by press-bonding the ink receiving layer coated on the base paper to a heated metal roll and drying it. In this case, the temperature of the metal roll is preferably 70 to 120 ° C., and the maximum surface roughness Rmax of the metal roll is preferably 5.0 μm or less.

  If the temperature of the metal roll is less than 70 ° C., it is difficult to copy the mirror surface, and the image clarity and glossiness are reduced. If the temperature exceeds 120 ° C., the moisture content in the paper is too low. There is an inconvenience of getting worse.

  Further, if the maximum surface roughness Rmax of the metal roll exceeds 5.0 μm, it becomes difficult to transfer a smooth surface. Specific gloss forming means includes a method of finishing by press-bonding to a heated metal roll while the ink receiving layer is in a wet state (wet casting method), or after drying the ink receiving layer once A method of finishing by re-wetting and pressure-bonding to a heated metal roll and drying (rewet cast method), or by directly applying a coating solution for the gloss layer to a heated metal roll and applying the coating. It is also possible to adopt a method (precast method) that finishes by pressing the ink receiving layer while it is wet to some extent and drying it.

  The coating liquid used for forming the ink receiving layer contains the pigment and the binder. The ratio of the binder to 100 parts by weight of the pigment is preferably 10 to 30 parts by weight. If the binder is less than 10 parts by weight, the strength of the coating layer may be insufficient. On the other hand, if the binder exceeds 30 parts by weight, ink absorbability may be impaired.

  Moreover, it is preferable that the glass transition temperature of a binder is -20 degreeC-80 degreeC. When the glass transition temperature exceeds 80 ° C., the coating layer may not exhibit sufficient rubber elasticity when pressure-bonded to a heated metal roll, and good smoothness may not be imparted. On the other hand, when the glass transition temperature is less than −20 ° C., film formation of the resin proceeds more than necessary due to the heat of the metal roll, the porosity of the paper surface decreases, and the ink absorbability decreases.

  Various auxiliary agents can be added to the coating solution as necessary. Examples of auxiliary agents include dispersants, water retention agents, thickeners, antifoaming agents, antiseptics, dyes, water resistance agents, fluorescent dyes, preservatives, ultraviolet absorbers, mold release agents, lubricants, crosslinking agents, and the like. An organic cation agent etc. can be mentioned.

As a coating method of the coating liquid, for example, the coating can be performed using a known coating machine such as an air knife, a roll coater, a bar coater, a comma coater, or a blade coater. The coating amount of the coating liquid is preferably 5 to 40 g / m ² and more preferably 10 to 30 g / m ² in terms of solid content. If the coating amount of the coating solution is less than 5 g / m ² , high gloss may not be obtained. On the other hand, if it exceeds 40 g / m ² , the coating layer strength is insufficient, or gloss treatment is performed by a casting method. When doing so, the drying property on the metal roll may deteriorate, and pinholes may occur in the outermost layer.

The smoothness of the ink-receiving layer surface of the ink jet recording paper of the present invention under the pressure of 20 kg / cm ² by microtopography (before forming the glossy layer) is Rp = 1.0-5. The smoothness under a pressure of 20 kg / cm ² by microtopography on the gloss layer surface is preferably Rp = 2.0 μm or less. The smoothness Rp by the microtopograph is a physical quantity proportional to the average depth of the dents on the sample surface that is crimped to the reference plane. The smaller the value of the smoothness Rp, the smaller the dent amount, the better the smoothness and the better the glossiness. Is done. Furthermore, the smoothness Rp is measured at 10 points or more in the width direction and the direction perpendicular to the measurement sample at intervals of 10 cm, and the average value of the measured values can be taken to evaluate the macro smoothness. .

However, if the smoothness of the ink receiving layer surface (before formation of the glossy layer) under a pressure of 20 kg / cm ² under a pressure of 20 kg / cm ² is smaller than Rp = 1.0 μm, the ink absorbability is lowered, and printing blur occurs. In addition, there is a problem in that the paper is not elastic and cannot be used. On the other hand, when the smoothness of the ink receiving layer surface (before forming the glossy layer) under a pressure of 20 kg / cm ² under a pressure of 20 kg / cm ² is greater than Rp = 5.0 μm, the surface smoothness when the coating solution for forming the glossy layer is applied. Therefore, it is not possible to obtain an ink jet recording paper having excellent gloss. In addition, even when the glossiness of the gloss layer under a pressure of 20 kg / cm ² under a pressure of 20 kg / cm ² is larger than Rp = 2.0 μm, it is not possible to obtain an ink jet recording paper having excellent gloss feeling.

In the method of forming the gloss layer by the casting method, as shown in FIG. 1, the paper 1 is cast by pressing the paper 1 against the cast drum (metal roll) 3 with the pressing roll 2 in the direction indicated by the arrow 4. Since the glossy layer is formed on the surface 1a in contact with the drum 3, the smoothness of the surface 1b opposite to the surface 1a on which the glossy layer is formed also affects the formation of the glossy layer. Therefore, it is preferable that the smoothness under a pressure of 20 kg / cm ² by the microtopograph on the side of the base paper opposite to the surface on which the glossy layer is provided via the ink receiving layer is Rp = 5.0 to 10.0 μm. . This is because if Rp = 5.0 μm or less, the problem arises that the paper becomes stiff and unusable, and if Rp = 10.0 μm or more, the image clarity and glossiness decrease.

In order to manufacture the ink jet recording paper of the present invention, for example, the following method can be employed. That is, the smoothness of the ink receiving layer surface under a pressure of 20 kg / cm ² under a pressure of 20 kg / cm ² is Rp = 1.0 to 5.0 μm and the surface of the base paper opposite to the surface on which the glossy layer is provided is 20 kg. Smoothing process by calendering on the side of the base paper opposite to the surface on which the glossy layer is provided and the ink receiving layer so that the smoothness under pressure of / cm ² is Rp = 5.0 to 10.0 μm. Next, the gloss layer is smoothed by a casting method so that the smoothness of the gloss layer surface under a pressure of 20 kg / cm ² under a pressure of 20 kg / cm ² is Rp = 2.0 μm or less. Thus, the ink jet recording paper of the present invention can be manufactured.

  In the above method, the calendering is preferably a method in which smoothing treatment is performed while heating with a calendar composed of a combination of metal rolls and elastic rolls having at least two nips, and the number of calendar stages is large. As the ink absorbency decreases, the smaller one is more preferable.

  In the ink jet recording paper of the present invention, the image clarity measured in accordance with JIS-H8866-2 is preferably 40 (%) or more, and the larger the numerical value, the better. The image clarity is an important characteristic as an index of how clearly and when an object is reflected on the surface of the coating film, the image is projected without distortion. In accordance with JIS-H8866-2, the image clarity is measured through an optical comb that moves reflected light (light receiving angle 45 ° or 60 °) applied to the test piece through the slit at an angle of 45 ° or 60 °. It is a numerical value obtained according to the following equation (3) from the change waveform (for example, see FIG. 2) of the received light amount. The ratio of the bright portion (portion through which light is transmitted) to the dark portion (portion through which light is not transmitted) of the optical comb is 1: 1, and the width of the optical comb is 0.125, 0.25, 0.5, 1.0. And 2.0mm.

Formula (3) C (n) = [(M−m) / (M + m)] × 100
Here, C (n): image clarity (%) when the width of the optical comb is n (mm)
M: Maximum wave height when the width of the optical comb is n (mm)
m: Minimum wave height when the width of the optical comb is n (mm) The numerical value of the image clarity that evaluates the properties of the specimen surface, which represents the sharpness or distortion of the image when the image is projected on the specimen surface. It can be said that it is suitable as an index of glossiness.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples.
(1) Production example of ink jet recording paper with RP = 0.5-10.0 μm under pressure of 20 kg / cm ² by microtopography on the surface of the ink receiving layer << Manufacture of base paper >>
Blend 100 parts by weight of hardwood kraft pulp with 3 parts by weight of sulfuric acid band, 10 parts by weight of sizing agent and 10 parts by weight of talc, make paper with a long net paper machine, and apply starch on the paper surface with a size press. A base paper having a weight of 150 g / m ² was obtained.
<Formation of ink receiving layer>
Silica (trade name Silica Fine Seal X45, manufactured by Tokuyama Corporation), particle size 4.5 μm, BET specific surface area 300 m ² / g 100 parts by weight, sodium hydroxide 1 part by weight, polyvinyl alcohol (product of Kuraray Co., Ltd.) The coating solution consisting of 15 parts by weight of the name PVA117, glass transition temperature = 0 ° C., and 5 parts by weight of the ink fixing agent (trade name SR1001 manufactured by Sumitomo Chemical Co., Ltd.) was used as described above using an air knife coater. On the obtained base paper, 10 g / m ^{2 in} terms of solid content is coated, dried by a scuff dryer, and then the base paper 5 coated with the coating liquid is formed into a calendar as shown in FIG. Through the microtopograph, the smoothness under a pressure of 20 kg / cm ² is Rp = 0.5 to 10.0 μm, the lower side of the ink receiving layer and the side opposite to the surface provided with the ink receiving layer Undercoat paper having a smoothness of Rp = 4.5 to 11.3 μm under a pressure of 20 kg / cm ² by microtopography on the base paper surface was obtained.

In FIG. 3, 6 is a metal roll, 7 is an elastic roll, and the metal roll 6 was heated to 100 ° C.
<Glossy layer formation>
Next, 100 parts by weight of colloidal silica (trade name Colloidal Silica Snowtex XL manufactured by Nissan Chemical Industries, Ltd., particle size 0.05 μm, BET specific surface area 100 m ² / g), acrylic resin (manufactured by Daicel Chemical Industries, Ltd.) 5 parts by weight of product name 46753), 10 parts by weight of polyvinyl alcohol (trade name PVA117 manufactured by Kuraray Co., Ltd., glass transition temperature = 0 ° C.), and ink fixer (trade name Polyfix 700 manufactured by Showa High Polymer Co., Ltd.) ) Using an air knife coater, a coating solution consisting of 5 parts by weight was coated on the lower layer of the ink-receiving layer at a solid content of 13 g / m ² , dried with a scuff dryer, and then dried. The layer is rewet with water and pressed onto a cast drum heated to 100 ° C. (with a maximum surface roughness of 0.5 μm) and dried to give a high gloss mirror finish. To obtain an ink jet recording paper of Kenhen 1-9. Table 1 below shows the numerical values of RP under the pressure of 20 kg / cm ² by microtopography of the gloss layer surface, together with the evaluation on “image clarity” and “smear” on the gloss layer surface of test pieces 1 to 9.
(2) Example of production of inkjet recording paper having a maximum surface roughness of the cast drum of 0.1 to 10.0 μm at the time of the casting treatment The smoothness under the pressure of 20 kg / cm ² by microtopography is the same as above. Rp = 0.8 to 6.2 μm The smoothness under a pressure of 20 kg / cm ² by microtopography of the lower surface of the ink receiving layer and the surface of the base paper opposite to the surface provided with the ink receiving layer is Rp = Priming paper of 4.8 to 11.3 μm was obtained, and the same treatment as above was performed, except that the maximum surface roughness of the cast drum at the time of gloss layer formation was changed in the range of 0.1 to 10.0 μm. Thus, inkjet recording paper of test pieces 10 to 17 was obtained. Table 2 below shows the RP values under the pressure of 20 kg / cm ² by microtopography of the gloss layer surface, together with the evaluation on “image clarity” and “smear” on the gloss layer surface of the test pieces 10 to 17.
(3) Evaluation of characteristics Evaluation of “image clarity” and “smear” on the ink jet recording paper of the obtained test pieces 1 to 17 was performed by the following methods.
<Image clarity>
It measured according to the method prescribed | regulated to JIS-H8866-2. Tables 1 and 2 show the results when the angle of incident light and reflected light is 60 ° and the width of the optical comb is 2.0 mm.
《Bludge》
Using an inkjet printer (PM-G800 manufactured by Seiko Epson Corporation), red, green, and blue, each composed of overlapping colors of cyan, magenta, and yellow inks, at a temperature of 23 ° C. and a humidity of 50%, respectively. Solid printing (size: 3.0 cm × 3.0 cm) was performed, and the degree of bleeding after printing for 30 minutes was visually observed and evaluated according to the following criteria. The results are shown in Tables 1 and 2.
A: No ink bleeding is observed.
○ = Slight ink bleeding is observed, but there is no practical problem.
Δ = Boundary disturbance due to ink bleeding.
X = Ink bleeding is clearly seen as a whole.

  As apparent from Tables 1 and 2, the image properties of the examples of the present invention (test pieces 2 to 6, 10 to 14) are 40% or more, the glossiness of appearance is good, and the ink There was no blur at all. In addition, no scratch was observed on each test piece.

  However, ink smearing was observed in the test piece 1 of Rp = 0.5 μm by microtopography on the surface of the ink receiving layer.

  Further, the values of image clarity of the test piece 7 with Rp = 5.3 μm and the test piece 8 with Rp = 10.0 μm by the microtopograph on the surface of the ink receiving layer were low, and the apparent glossiness was also poor. In particular, since the test piece 8 has a high Rp of 11.3 μm by the microtopograph on the surface of the base paper opposite to the surface on which the ink receiving layer is provided, the numerical value of image clarity is considerably low.

  The test piece 9 has Rp = 3.0 μm by the microtopograph on the surface of the ink receiving layer, but the Rp by the microtopograph on the base paper surface opposite to the surface on which the ink receiving layer is provided is as high as 10.8 μm. The numerical value of image clarity was low, and the glossiness of appearance was also poor.

  Furthermore, the numerical value of the image clarity of the test piece 15 having a maximum surface roughness of the cast drum of 5.2 μm and the test piece 16 of 10.0 μm was low, and the apparent glossiness was also poor.

  Further, the test piece 17 has a maximum surface roughness of the cast drum of 3.0 μm, but the Rp by the microtopograph on the side of the base paper opposite to the surface provided with the ink receiving layer is as high as 10.5 μm. The numerical value of was low and the glossiness of appearance was also bad.

It is a figure for demonstrating an example of a cast processing system. It is a figure which shows the example of the light received waveform from a test piece. It is a schematic block diagram which shows an example of a calendar.

Explanation of symbols

1 Paper 2 Pressing Roll 3 Cast Drum 5 Base Paper 6 Metal Roll 7 Elastic Roll

Claims (4)

In an ink jet recording paper having an ink receiving layer on a base paper and a gloss layer provided on the ink receiving layer, the smoothness of the ink receiving layer surface under a pressure of 20 kg / cm ² by microtopography is Rp = 1. An inkjet recording paper having a smoothness under a pressure of 20 kg / cm ² by microtopography on the surface of the glossy layer of Rp = 2.0 μm or less. ^2. The ink jet according to claim 1, wherein the smoothness of the base paper surface opposite to the surface on which the glossy layer is provided under a pressure of 20 kg / cm <2> by a microtopograph is Rp = 5.0 to 10.0 [mu] m. Recording sheet.   The inkjet recording paper according to claim 1 or 2, wherein the image clarity of the glossy layer surface measured in accordance with JIS-H88686-2 is 40 (%) or more. In a method for producing an ink jet recording paper having an ink receiving layer on a base paper and having a gloss layer on the ink receiving layer, the surface of the ink receiving layer has a smoothness under a pressure of 20 kg / cm ² by a microtopograph. , Rp = 1.0 to 5.0 μm, and the smoothness under pressure of 20 kg / cm ² by the microtopograph on the side of the base paper opposite to the surface on which the glossy layer is provided is Rp = 5.0 to 10.0 μm. The surface of the base paper opposite to the surface on which the glossy layer is provided and the ink receiving layer are simultaneously subjected to a smoothing process by calendering, and then the surface of the glossy layer under a pressure of 20 kg / cm ² by microtopography is applied. A method for producing an ink jet recording paper, comprising performing a smoothing process on a glossy layer by a casting method so that the smoothness becomes Rp = 2.0 µm or less.

Images