JP2000250250A - Recording paper and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the combination use of electrophotographic transfer paper for a copying machine, etc., and recording paper for an ink jet printer, etc., and to make it possible to exhibit performance excellent as the recording paper for full-color electrophotography and color ink jet. SOLUTION: The specific volume resistivity of the recording paper having a basis weight within a range of 75 to 85 g/m2 and whiteness of >=84% (JIS-P8123 method) is 1.0×1011 to 1.0×1012 Ω/cm (JIS-K6911 method). The coefficient of absorption KA by a Bristow's test is specified to 14 to 15 ml/m2/sec1/2 (J.TAPPINo.51 method). Further, the front and rear smoothness is represented as 100 to 200 seconds (by J.TAPPINo.5B method).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a recording sheet,
More particularly, the present invention relates to a recording paper which is used in combination with an electrophotographic transfer paper and an ink jet recording paper, and particularly exhibits excellent performance for full-color electrophotography and color ink jet, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, an ink jet recording system has
Since various ink droplets are ejected by various mechanisms to form and record ink dots on recording paper, the recording mechanism is extremely simple. In addition, the apparatus body is small and inexpensive, the noise at the time of recording is small, and colorization, high density, and high speed have been further advanced, and the apparatus has been rapidly spreading in recent years. Therefore, recently, the transfer paper for electrophotography has often been used in combination with an ink-jet type copying machine or printer. As described in JP-A-8-30011 and JP-A-8-50366, there is a description that an ink jet image quality is improved by improving the sizing process of an electrophotographic transfer paper and is also used for an electrophotographic paper. ing.

However, the recording papers proposed in these publications have been able to obtain good image quality in monochrome image quality, but have poor uniformity in full-color electrophotography, and have poor image quality at low humidity. However, in reality, satisfactory image quality has not yet been obtained. Conventional full-color electrophotographic recording paper is, for example, 8
The basis weight is relatively large, such as 0 g / m ² , to increase the opacity, thereby preventing strike-through of the toner image. When such a paper having a large basis weight is used for ink jet, even if an appropriate sizing is performed, the color density of the ink permeated into the paper layer is blocked by this opacity, and the printed It tends to reduce the saturation of the ink. In addition, there is a problem that bleeding such as feathering along paper fiber streaks or bleeding that occurs when inks of different colors adjacent to each other at the time of multi-color bleeding occur to significantly reduce print quality.

[0004]

As described above, the ink-jet recording system is simple, the apparatus main body is small and inexpensive, and color, high-density, and high-speed are further advanced. Accordingly, in full-color PPC in the electrophotographic recording system, image formation, transfer failure and the like are improved, and there is a demand for recording paper used in both of these recording systems. However, in the proposal of the above-mentioned publication, full-color electrophotography has poor uniformity of an image and has a problem such as image quality at low humidity. To prevent strike-through of a toner image, the basis weight is increased to increase opacity. In fact, problems such as a reduction in the color density and the saturation of printed ink in ink-jet recording and the occurrence of feathering, bleeding, and the like have not yet been sufficiently solved.

Accordingly, an object of the present invention is to provide a uniform image in full-color electrophotography, and to form a good image even in a low-humidity environment.
It is excellent as an electrophotographic recording paper for printing, and even when used as an ink jet paper, the ink density to be transferred is clear, and bleeding such as feathering and bleeding is prevented, and ink jet recording with excellent print quality. An object of the present invention is to provide recording paper which is paper and is used in both of these recording systems.

[0006]

Means for Solving the Problems In view of the above problems, the present inventors have made intensive studies to achieve these problems, and as a result, increased the amount of the conductive agent in the sizing agent to increase the volume resistivity of the surface of the recording paper. For example, by reducing the volume resistivity in a low-humidity atmosphere of 20 ° C. × 65% RH to a volume resistivity of 1.0 × 10 ^{11 to} 1.0 × 10 ¹³ Ω · cm in a humidity environment at the time of use. In addition, image formation and transfer defects in full-color PPC are improved, and stable image quality is obtained. In addition, by examining various fillers to be included, print density, color blur / bleeding, etc. can be obtained even for an inkjet recording paper. The inventors have found that the present invention is improved, and have completed the present invention.

That is, according to the present invention, the basis weight is 75 to 85 g.
/ M ² , the recording paper having a whiteness of 84% or more according to the JIS-P8123 method.
The volume resistivity according to IS-K6911 method is 1.0 ×
10 ^{11 to} 1.0 × 10 ¹³ Ω · cm. T
APPIN No. The absorption coefficient Ka according to the Bristow test conforming to the Method 51 is in the range of 14 to 15 ml / m ² · sec ^1/2 . TAPPI No. A recording paper characterized in that the front and back smoothness conforming to the 5B method is in the range of 100 to 200 seconds, and the volume resistivity, the absorption coefficient Ka and the front and back smoothness are simultaneously in the above numerical range.

Further, the present invention provides a method for producing the above-mentioned recording paper, wherein the basis weight is in the range of 75 to 85 g / m ² .
A recording paper having a whiteness of 84% or more according to JIS-P8123 and a volume resistivity of 1.0 × 10 ^{11 to} 1.0 × 10 ¹³ Ω · cm according to JIS-P6911 is used. In producing, in aqueous slurries of pulp,
An inner sizing agent and its binder polymer (A) are added, and then 4 to 8 per pulp solid content conversion as a filler.
The paper material obtained by adding the white extender pigment of weight% is made into a paper by a paper machine so as to have the above-mentioned basis weight, and then the binder is prepared.
In an aqueous solution of the polymer (B), the binder was size-pressed with a surface sizing agent containing 0.5 to 5% by weight of an antistatic agent and a surface sizing agent based on the solid matter of the polymer (B). Later, J. TAPPI No. Provided is a method for producing recording paper, which comprises performing a press treatment in a machine calendering step so that the front and back smoothness conforming to the 5B method is 100 to 200 seconds.

According to the present invention, the basis weight is 75 to
85 g / m ² , the whiteness is 84% or more, and the volume resistivity of the surface of the paper is reduced by increasing the amount of the conductive agent in the surface sizing agent to 1.0 × 10 ^{11 to} 1.0 × 1
By setting it within the range of 0 ¹³ Ω · cm, as a full-color electrophotographic recording paper, image strikethrough (show-through) is prevented and double-sided recording can be performed. The obtained image is uniform and low humidity. A recording sheet on which an image with a good density is formed even at the time is obtained. In addition, 2 white fillers to be included
Papers having a surface sizing after adding 0.5 to 10% by weight in combination of at least TAPPI
By performing a press process so that the front and back smoothness conforming to the No. 5B method is 100 to 200 seconds, the dot density is high and the color is clear, and the bleeding such as bleeding and feathering can be obtained as a color inkjet recording paper. It is possible to obtain recording paper that is excellent in suppressed print quality and that maintains good workability in both of these recording methods, and that is used in combination with them.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, the recording paper according to the present invention is used as an electrophotographic recording paper and an ink jet recording paper, and is characterized in that good full-color images and recording are achieved. Recording paper. Hereinafter, embodiments of a recording sheet and a method for manufacturing the same according to the present invention will be described in detail.

In the present invention, as described above, the basis weight is in the range of 75 to 85 g / m ² , and preferably,
By increasing the opacity to 80 to 85 g / m ² ,
Through-through (show-through) of the toner image is effectively prevented. Moreover, as described above, in spite of a relatively large basis weight as compared with the related art, particularly, a good print density can be obtained even with an inkjet recording paper. However, in the related art, when such a paper having a large basis weight is used, for example, for ink jet printing, even if an appropriate sizing process is performed, the color density of the ink that has permeated into the paper layer is increased. It was blocked by opacity and tended to reduce the saturation of the printed ink.

Therefore, the recording paper of the present invention is preferably used as a filler, as an inorganic extender, preferably in a range of 4-8.
It is added (filled in) in the range of weight%. If the addition amount is less than 4%, the whiteness of the paper quality decreases, and for example,
The print density of the inkjet is reduced, and the image quality of the inkjet and the full-color PPC image are deteriorated. On the other hand, if it exceeds the upper limit of 8%, the surface strength of the paper quality is reduced and the powder tends to fall off, causing clogging of the ink jet head (nozzle), mixing into the photosensitive member of the full-color PPC or the developer, and image quality. Is significantly impaired.

In the present invention, the whiteness of the paper is preferably 84% or more, more preferably, depending on the amount of the filler added or the type of extender used as the filler.
It is preferable that it is 85% or more. This whiteness is 84
%, The contrast of the full-color PPC image quality is reduced, and the visual appearance is unfavorably reduced.

[0014] In the present invention, an infill sizing agent is conventionally added to a paper stock made by a paper machine (papermaking) as a paper-strengthening aid. The amount of addition is 0.1 to
It is appropriately added in the range of 6% by weight. In the present invention,
After making this stock in addition to these infill sizing agents,
The paper is subjected to size press treatment using a surface sizing agent.
Here, as a surface sizing treatment in the present invention, an antistatic agent such as an inorganic salt, an organic salt and a surfactant is used in a 4 to 12% by weight aqueous solution of a binder and a sizing agent, for example, PVA, For example, a surface sizing agent containing an AKD sizing agent can be suitably used as appropriate.

In the present invention, the above-mentioned aqueous binder solution is preferably in the range of 5 to 10% by weight,
In the aqueous binder polymer solution, an antistatic agent in an amount larger than the conventional amount is added as appropriate, preferably in the range of 0.1 to 5% by weight, based on the solid content of the binder polymer. can do. Thereby, the volume resistivity value of the obtained recording paper is, as described above,
Preferably, 1.0 × 10 ^{11 to} 1.0 × 10 ¹³ Ω · c
m, more preferably 5.0 × 10 ^{11 to} 5.0 × 10 ¹²
The recording paper is in the range of Ω · cm. Here, the volume resistivity is less than 1.0 × 10 ¹¹ Ω · cm,
If it exceeds 0 ¹³ Ω · cm, the image quality in full-color PPC, especially in full-color PPC, is significantly reduced. Further, the antistatic agent was further increased to increase the volume resistivity value to 1.0.
Even if the density is reduced to less than × 10 ¹¹ , the low-temperature image quality in full-color PPC and the transfer failure are not improved, but the added amount is increased, and it is only economically disadvantageous.

More specifically, when the volume resistivity is high, usually in an electrophotographic image forming process,
When the toner is transferred from the photoconductor to the recording paper, the charge cannot smoothly move to the surface of the recording paper, and the transfer rate does not tend to increase. On the other hand, if it is too low, the charge at the time of transfer leaks through the recording paper, causing transfer failure. Further, in monochrome electrophotography, a sufficient transfer rate can be obtained even when it exceeds 1.0 × 10 ¹⁴ Ω · cm. However, in full-color electrophotography, when two or more colors of toner are transferred to the same place,
In particular, it is important that the resistivity is 1.0 × 10 ¹³ Ω · cm or less. For example, when forming a red image, using two color toners of yellow and magenta, there is no problem with the transfer of yellow, but the transfer rate of the transfer of magenta of the second color does not increase, and the uniformity of the toner is reduced. Insufficient orange color occurs.

Therefore, in the present invention, as described above, at the time of surface sizing, the above-mentioned various amounts of the antistatic agent are appropriately used, and an atmosphere of 20 ° C. × 65% RH (this humidity condition is As described above, preferably, the volume resistivity of the product recording paper (corresponding to the volume resistivity immediately after the packaging paper is opened) is 1.0 × 10 ^{11 to} 1.0 × 10 3.
¹³ Ω · cm, more preferably 5.0 × 10 ^{11 to} 5.0
It is preferable that the value be in the range of × 10 ¹² Ω · cm.

Further, as described above, a paper made by using a stock prepared by adding various amounts of the filling filler and adding various amounts of the filling sizing agent is used to further form a surface sizing agent. In the present invention, when the paper is subjected to a press treatment in a machine calendering step after the size press using the same, the smoothness of the front and back of the paper is preferably set to J.I. TAPPINo
It is preferable to apply a press process so that the smoothness according to the 5B method is 100 to 200 seconds. If the smoothness is less than 100 seconds, the unevenness of the paper surface is large, and a uniform and smooth toner image cannot be obtained on the image surface recorded by full-color electrophotography, which is a trouble as a recording paper for paintings and photographs. I came and I don't like it. Further, it is not preferable as a paper having a relatively high basis weight and requiring a high-grade feel because of its feel and texture. In order to require a more uniform toner image, the smoothness is more preferably set to 120 seconds or more. Also, if it exceeds 200 seconds,
Conversely, the porosity on the surface of the paper is reduced, and the absorption and drying speed of the ink is reduced. In particular, in a color inkjet, different colors adjacent to each other are bleeding and bleeding occurs. In addition, in the ink jet recording apparatus and the electrophotographic recording apparatus, non-feeding or multi-sheet feeding may occur at the time of paper supply, and furthermore, from the viewpoint of ensuring transportability and dischargeability in the apparatus, 200 seconds or less, preferably , 180 seconds or less.

In addition, as described above, papermaking, surface sizing,
The recording paper obtained by pressing is JIS-P81
The surface strength based on the wax method of No. 29 is preferably
It is preferably in the range of 14 to 22A. If the strength is less than 14A, the surface strength of the paper quality is too low, which causes clogging of the ink jet printer head due to paper powder falling off (powdering), mixing of the full-color PPC into the photoreceptor and the developing material, and image quality. Will be significantly degraded. On the other hand, if it exceeds 22A, it is not preferable because in the image formation of full-color PPC, the fixability of the toner is hindered, and the image tends to peel off.

In the present invention, as described above, the basis weight is 75 to 85 g / m ² and the whiteness is 84%.
As the recording paper having the above, the opacity of the obtained recording paper is determined by JIS as a characteristic related to the kind of white extender pigment to be included in connection with these and the amount of the above-mentioned addition.
As opacity according to -P8138,
It is suitable that it is 88% or more, more preferably 90% or more. If the opacity is 88% or less, so-called strikethrough (show-through) cannot be prevented in ink-jet printing and full-color PPC images, and as a result, double-sided recording is hindered and is not preferable.

In view of the above, in the present invention, as a stock for preparing recording paper having the above-mentioned characteristics, a paper pulp material as a main material, an extender to be filled in, and a sizing agent to be filled (paper strength improving aid) Further, a surface sizing agent, an antistatic agent, and the like can be mentioned. In the present invention, as long as there is no particular problem as the recording paper for electrophotography and ink jet, these material types and the amounts used thereof are appropriately selected and used. Can be.

Therefore, as the pulp material, LBKP, N
Chemical pulp represented by BKP, NBSP, LBSP, GP, TMP, etc., mechanical pulp, various kinds of recycled pulp, and the like. Rosin size,
Alkyl ketene dimer (AKD), alkenyl succinic anhydride, petroleum resin size, epichlorohydrin, cationized starch, polyacrylamide, polyamine, melamine formalin resin, urea formalin resin, polyvinyl alcohol (PVA), polyvinyl hydrin, sodium polyacrylate , Carboxyl methyl cellulose (CMC)
In the present invention, these are used alone or in an appropriate combination of two or more, and AKD, PVA, cationic starch, CMC and the like are preferably used.

Examples of the surface sizing agent include styrene / acrylic acid copolymer, styrene / methacrylic acid copolymer, acrylonitrile / vinyl formal / acrylic acid ester copolymer, olefin / malenic acid copolymer, styrene / malenic acid copolymer, AKD, PVA, polyvinylpyrrolidone, sodium polyacrylate, CMC and the like.
AKD, PVA, cationic starch, CMC and the like are preferably used alone or in an appropriate combination of two or more thereof.

Examples of the antistatic agent include inorganic salts such as sodium chloride, potassium chloride and calcium chloride; cationic salts such as primary amine salts, tertiary amine salts, quaternary amine salts, and pyridine derivatives; , Sulfated ester, sulfated amide oil, olefin sulfate, fatty alcohol sulfate, alkyl sulfate, fatty acid ethyl sulfonate, alkylnaphthalene sulfonate, alkylbenzene sulfonate, succinate sulfonate , Phosphoric acid ester salts, etc., polyhydric alcohol partial fatty acid esters, fatty alcohol ethylene oxide adducts, fatty acid ethylene oxide adducts, fatty amino or fatty amide ethylene oxide adducts, alkylphenol ethylene oxide adducts , Alkyl naph Ethylene oxide adducts of ethylene glycol, ethylene oxide adducts of partial fatty acid esters of polyhydric alcohols, nonionics such as polyethylene glycol, carboxylic acid derivatives, and amphoteric surfactants such as imidazoline derivatives. These may be used alone or in appropriate combination of two or more kinds, and sodium chloride, quaternary amine salts and the like are preferably used.

As the white extender pigment to be filled, kaolin, talc, synthetic smectite, sericite, calcium carbonate, titanium dioxide, satin white, magnesium silicate, calcium silicate, aluminum hydroxide, barium sulfate, white carbon, synthetic carbon In the present invention, these are used singly or in an appropriate combination of two or more kinds. Particularly, in the present invention, preferably, calcium carbonate, titanium dioxide, white carbon or the like is used.
It is preferred to use a combination of more than one species. Also,
In addition to these additives, if necessary, conventionally known paper strength enhancers, retention agents, fixing agents, dyes, defoamers, pitch control agents, and other papermaking aids can be used as appropriate. .

As a paper machine for making these stocks,
For example, a fourdrinier paper machine conventionally known in the papermaking industry, a twin-wire paper machine, a combination paper machine, a round mesh paper machine,
A Yankee paper machine or the like can be used as appropriate. Also,
To apply a surface sizing treatment to the paper made, as a coating amount, conventionally, usually 0.01 to 0.20 g
/ M ² in the size press, and the coating method is a conventional size press, gate roll size press, film transfer type size press, rod coater, bill blade, short dwell coater and other devices. Can be mentioned.

[0027]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto. The physical properties of the recording paper and the performances of the recording paper for full-color electrophotography and ink-jet printing were evaluated by the methods described below using the following two test apparatuses.

1. Various physical properties of recording paper (1) Volume specific resistance HIGHRESISTANCE METE manufactured by HYP
R-4329A and RESISTIVITY-CELL
According to JIS-K6911 method, the reading (Ω value) obtained when the recording paper was charged with an applied voltage of 25 V for 60 seconds in an atmosphere of 20 ° C. and 65% RH using JI-1600A was measured by JI.
From the paper thickness (cm) obtained by the SP 8118 method, reading (Ω) × 19.6 / paper thickness (cm) = volume resistivity (Ω)
Cm) is required. (2) Absorption coefficient KaJ. TAPPI No. The absorption coefficient Ka (ml / m ² · sec ^1/2 ) is determined by the Bristow test based on the method 51. (3) Front and back smoothness TAPPI No. Recording is performed in accordance with the 5B method, and the smoothness (seconds) of the front and back sides is obtained. (4) Whiteness The whiteness is determined by a method based on JIS-P8123. (5) Surface strength The surface strength is determined by a method based on the wax method of JIS-P8129. (6) Opacity Opacity is determined by a method based on JIS-P8138.

2. Evaluation by Full-Color Electrophotographic Recording Apparatus An image was formed on recording paper by using Ricoh's full-color electrophotographic recording apparatus PRETER350 and PRETER650. (7) Show-through (through strike-through) After exposing the recording paper to an atmosphere of 20 ° C. × 65% RH for 3 hours or more, a single-color solid image is formed such that the density measured by a Macbeth densitometer becomes 1.0 for each color. I do. The image is visually observed from the back side, and the case where the boundary between the solid image and the white background portion is clearly recognized is evaluated as x, and the case where the boundary is unclear and unrecognizable is evaluated as ○. (8) Humidity Resistance of Image Forming Density After exposing the recording paper to an atmosphere of 20 ° C. × 65% RH for 3 hours or more, solid images of red, purple, and black are respectively formed. Further, the recording paper exposed to a low humidity atmosphere of 20 ° C. × 30% RH for 3 hours or more under the same toner transfer conditions as above,
Solid purple and black images are formed. Then, the humidity resistance of the image density formed on the recording paper exposed to the different humidity atmosphere was visually observed, and if there was no difference between the color densities of the two, it was marked with a circle, and the color and density difference When there is a mark, the humidity resistance of the image forming density of each recording paper is evaluated as a cross. (9) Image uniformity The image obtained in the section (8) is visually observed, and the image uniformity is evaluated as x when the unevenness is observed in the image density, and as o when the unevenness is not observed.

3. Evaluation by Inkjet Recording Apparatus BJC-610JW, EP manufactured by Canon Inc. for recording paper
SO's MJ100C and HEWLETT PACKKA
An image was formed using an ink jet recording apparatus of HP850C manufactured by RD, and the following evaluation was performed. (10) Print density After exposing the recording paper to an atmosphere of 20 ° C. × 65% RH for 3 hours or more, solid images of magenta, cyan, yellow, and black are formed, and a Macbeth densitometer (RD-Macbeth) is used.
The density measured in 914) is 1.25 or more for each color for BJC-610JW, and 0.9 for black for MJ100C.
5 or more, magenta is 0.80 or more, and cyan is 0.8
5 or more, yellow is 0.75 or more, and HP850C
Indicates that black is 1.40 or more, and that magenta, cyan and yellow are 1.10 or more, they are marked with a circle and these are marked with 0.
If even one color falls short, each is evaluated as a cross. (11) Bleeding After exposing the recording paper to an atmosphere of 20 ° C. × 65% RH for 3 hours or more, 0.5 mm line images of magenta, cyan and black were respectively formed in a solid image of yellow, and different colors were formed. The presence or absence of bleeding caused by bleeding when ink is adjacent is visually observed. Further, the same applies to the case where magenta, yellow and black 0.5 mm line images are respectively formed in the cyan image and the case where cyan, yellow and black 0.5 mm line images are respectively formed in the magenta image. Then, the presence or absence of bleeding is observed and evaluated in the same manner. (12) Feathering After exposing the recording paper to the atmosphere of 20 ° C. × 65% RH for 3 hours or more, the magenta, cyan, yellow, and black color filters are exposed.
A line image of 5 mm was formed, and when one or more colors of feathering (the occurrence of bleeding along the fiber streaks of the paper-made pulp) occurred, the evaluation was evaluated as x. (13) Runability and workability PR of Ricoh's full-color electrophotographic recording device on recording paper
ETER350 and PRETER650, and BJC-610JW and B of the inkjet recording apparatus manufactured by Canon Inc.
Using JC-455J, the running property, workability, occurrence of curl trouble, and the like of the recording paper when copying and printing in an atmosphere of 20 ° C. × 65% RH are evaluated. In particular, when all of these are not hindered, the mark is marked with a circle.Especially, when the overlapped feed, paper jam, or the workability due to electrostatic charging is slightly affected, the mark is marked with a triangle. Stuffy,
When a problem occurs in any of the workability due to electrostatic charging, etc., evaluate each as x mark

Example 1 Hardwood bleached kraft pulp 1
Alkyl ketene dimer sizing agent (AS202, trade name, manufactured by PMC Japan) as a filling sizing agent in pulp consisting of 50% by weight adjusted to 450 ml CSF by disintegration and beating treatment at 00% .2
In addition, 0.5% by weight of cationic starch and 0.5% by weight of cationic starch were added, and 3.5% by weight of calcium carbonate and 1.5% by weight of white carbon were added as fillers in terms of solid content of pulp to prepare a stock. The stock was made with a Fourdrinier under the conditions adjusted to a basis weight of 80 g / m ² and a density of 0.82 g / cm ³ . Furthermore, polyvinyl alcohol (Kuraray's PVA-
H) In a 5% by weight aqueous solution, 20% by weight of sodium chloride in terms of solids with respect to PVA, and as a surface sizing agent, an alkyl ketene dimer sizing agent (trade name S, manufactured by PMC Japan)
S-362) After 0.3% by weight was added and the size was pressed, the pressure was adjusted in the machine calendering step so that the smoothness became 140 seconds, to obtain the recording paper of Example 1.
Next, in a 20 ° C. × 65% RH atmosphere, the volume resistivity, the whiteness, and the Bristow test absorption coefficient at a predetermined front / back surface smoothness were measured. The results are shown in Table 1 together with each performance evaluation as a recording paper. The volume resistivity was measured in accordance with the front / back surface smoothness and the Risto test absorption coefficient, respectively.

Comparative Example 1 A recording prepared in the same manner as in Example 1 except that the machine calendar pressure was lowered and the pressure was adjusted so that the smoothness became 50 seconds, and all other conditions were the same as in Example 1. The same evaluation test as in Example 1 was performed on the paper, and the results are shown in Table 1.

(Example 2) In Example 1, except that 1% by weight of titanium dioxide was further added as a filler.
A stock was prepared under the same conditions as in Example 1. This paper stock was formed under the same conditions as in Example 1, then subjected to size pressing under the same conditions as in Example 1, and then adjusted in pressure so that the smoothness in the machine calendering step was 160 seconds. Recording paper was obtained. Next, the same evaluation test as in Example 1 was performed, and the results are shown in Table 1.

Comparative Example 2 In Example 2, paper containing 4.5% by weight of calcium carbonate, 3.5% by weight of white carbon, and 2.5% by weight of titanium dioxide in terms of solid content of pulp was added as a filler. Example 2 except that the fee was adjusted
Recording paper was obtained in the same manner as described above. Next, the same evaluation test as in Example 1 was performed, and the results are shown in Table 1.

Comparative Example 3 Paper obtained by adding 1.5% by weight of calcium carbonate, 1.5% by weight of white carbon, and 0.5% by weight of titanium dioxide in terms of solid content of pulp in Example 2 as a filler. Example 2 except that the fee was adjusted
Recording paper was obtained in the same manner as described above. Next, the same evaluation test as in Example 1 was performed, and the results are shown in Table 1.

(Example 3) A paper was made under the same conditions using the same stock as in Example 1, and further added to an aqueous solution of 10% by weight of polyvinyl alcohol (Pura-H manufactured by Kuraray Co., Ltd.). Quaternary ammonium salt (manufactured by Sanyo Chemical Industries, trade name: Chemistat 63)
0) The surface sizing agent used in Example 1, trade name SS-362 manufactured by Nippon PMC Co., Ltd.
After adding 3% by weight and size-pressing, the pressure was adjusted so that the smoothness was 180 seconds in the machine calendering step, and the recording paper of Example 3 was obtained. Next, the same evaluation test as in Example 1 was performed, and the results are shown in Table 1.

Example 4 A paper was prepared by using the same stock as in Example 1 and adjusting the lip opening so that the density was 0.82 g / cm ³ at a basis weight of 85 g / m ² . Example 3
In the same manner as in Example 4, a recording sheet of Example 4 was obtained. Next, the same evaluation test as in Example 1 was performed, and the results are shown in Table 1.

Example 5 The same paper stock as in Example 1 was used except that papermaking was performed by adjusting the lip opening so that the density was 0.82 g / cm ³ at a basis weight of 75 g / m ² . Example 3
In the same manner as in Example 4, a recording sheet of Example 4 was obtained. Next, the same evaluation test as in Example 1 was performed, and the results are shown in Table 1.

Comparative Example 4 In Example 3, 20% by weight of a quaternary ammonium salt (Chemistat 630, manufactured by Sanyo Chemicals Co., Ltd.) as a polymer antistatic agent in the sizing agent
Recording paper was obtained in the same manner as in Example 3 except that the above-mentioned was omitted. Next, the same evaluation test as in Example 1 was performed, and the results are shown in Table 1.

(Comparative Example 4) In Example 3, 20% by weight of a quaternary ammonium salt (Chemistat 630 manufactured by Sanyo Chemical Co., Ltd.) as a polymer antistatic agent in the sizing agent
Recording paper was obtained in the same manner as in Example 3 except that the above-mentioned was omitted. Next, the same evaluation test as in Example 1 was performed, and the results are shown in Table 1.

(Comparative Example 5) In Example 1, the filler was 3.5% by weight of calcium carbonate and the titanium dioxide was 1.5% by weight.
After the papermaking was performed under the same conditions using the same stock except for the above, a recording paper was obtained in the same manner as in Example 3. Next, the same evaluation test as in Example 1 was performed.
It was shown to.

(Comparative Example 6) A paper was prepared by using the same stock as in Example 1 and adjusting the lip opening so that the density was 0.82 g / cm ³ at a basis weight of 70 g / m ² . Example 3
Recording paper was obtained in the same manner as described above. Next, the same evaluation test as in Example 1 was performed, and the results are shown in Table 1.

As is clear from Table 1, the volume resistivity is in the range of 1.0 × 10 ^{11 to} 1.0 × 10 ¹³ Ω · cm. Absorption coefficient Ka by Bristow test based on TAPPI No. 51 method is 14 to 15 ml / m ² · sec
^In the range of ^1/2 . When the front and back smoothness based on the TAPPI No. 5B method is in the range of 100 to 200 seconds, and the volume resistivity, the absorption coefficient Ka and the front and back smoothness are simultaneously in the numerical ranges, the basis weight according to the present invention is 75 to 85 g. / M ^{2 in} the range of JIS-P812
Recording paper with a whiteness of 84% or more conforming to Law 3
It is well understood that they are used together as a recording paper for full-color electrophotography and ink jet recording.

[0044]

[Table 1]

[0045]

According to the present invention, the basis weight is 75 to 85 g /
m ² , the whiteness is set to 84% or more, the amount of the conductive agent in the sizing agent is increased, the volume resistivity of the paper surface is reduced, and the combination of the extender pigments to be included is examined. As a photographic recording paper, image strike-through (show-through) can be prevented and double-sided recording can be performed, a uniform image can be obtained, and an image with good density can be formed even at low humidity. Also, as an ink jet recording paper, the dot density is high, the color is clear, the bleeding such as bleeding and feathering are suppressed, and the printing quality is excellent, and good workability is exhibited in both of these recording methods. Accordingly, it is possible to provide a recording sheet used in combination therewith.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H086 BA05 BA32 BA33 BA35 BA37 BA41 BA43 BA44 4L055 AG11 AG12 AG18 AG19 AG48 AG64 AH01 AH13 AH27 AH37 BD13 BE02 BE08 EA07 EA08 EA10 EA11 EA12 EA32 EA34 FA15 FA30 GA09 GA10

Claims (9)

[Claims] (1) When the basis weight is in the range of 75 to 85 g / m ² ,
In a recording sheet having a whiteness of 84% or more according to the IS-P8123 method, the recording sheet has a volume resistivity according to the JIS-K6911 method of 1.0 × 10 ^{11 to} 1.0 × 1.
0 ¹³ Ω · cm. TAPPI No. 5
Absorption coefficient Ka by Bristow test conforming to Law 1 is 1
4 to 15 ml / m ² · sec ^1/2 . TAPPI No. A recording sheet having a front-to-back smoothness according to the 5B method in a range of 100 to 200 seconds. 2. The recording sheet according to claim 1, wherein the recording sheet is used for electrophotographic recording and ink jet recording, or is commonly used for these. 3. The recording paper according to claim 1, wherein the recording paper has a surface strength of 14 to 22 A according to the wax method of JIS-P8129. 4. The recording sheet according to claim 1, wherein the opacity of the recording sheet according to JIS-P8138 is 88% or more. 5. The recording paper contains 4 to 8% by weight of filler per pulp solid content, and the surface of the recording paper has
2. The recording paper according to claim 1, which has been sized with a sizing agent containing a conductive agent. 6. The at least one filler selected from the group consisting of titanium dioxide, calcium carbonate and white carbon.
The recording paper according to claim 5, wherein at least one kind of white extender is included. 7. When the basis weight is in the range of 75 to 85 g / m ² ,
When the whiteness according to the IS-P8123 method is 84% or more,
In producing a recording paper having a volume resistivity in the range of 1.0 × 10 ^{11 to} 1.0 × 10 ¹³ Ωcm according to the JIS-K6911 method, an aqueous slurry of pulp contains Add the binder polymer (A),
Next, a paper stock obtained by adding a white extender of 4 to 8% by weight per pulp solid content as a filler is made into a paper so as to have the above-mentioned basis weight with a paper machine, and then a binder polymer (B ) Is subjected to size pressing with a surface sizing agent containing 0.1 to 5% by weight of an antistatic agent and a surface sizing agent per solid content of the binder-polymer (B) in the aqueous solution of TAPPI No. A method for producing recording paper, comprising performing a press treatment in a machine calendering step so that the front and back smoothness conforming to the 5B method is 100 to 200 seconds. 8. The white extender pigment is titanium dioxide,
The method for producing a recording sheet according to claim 7, wherein the recording sheet is at least two or more kinds selected from calcium carbonate and white carbon. 9. The method according to claim 7, wherein the binder polymer (A) is a cationized starch, and the binder polymer (B) is a polyvinyl alcohol.