JP2001188378A - Information recording paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide information recording paper which ensures good image quality such as good image density and uniformity in density and good running performance even when used in a copying machine or a printer using a toner having a reduced particle diameter and attains low cost comparable to the cost of non-coated black-and-white recording paper. SOLUTION: On at least one face of paper, the proportion of voids having >=10 μm average equivalent circular diameter between the fibers of the surface is <=30%, and the surface is coated with 0.5-2.0 g/m2 surface coating layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic transfer paper mainly used in copying machines and printers using a full-color or monochrome electrophotographic system, and using a toner having a reduced particle size. The present invention relates to a non-coated type information recording paper which suppresses a toner from flowing into voids between fibers in a surface layer of a paper when transferred, and has printing characteristics and running characteristics excellent in printing density and density uniformity.

[0002]

2. Description of the Related Art In recent years, with the rapid spread of personal computers, software for personal computers, such as those for word processors, spreadsheets, and photo retouching, has spread.
Color documents can be easily created on personal computers, and along with this, full-color copiers and printers using electrophotography for offices and personal computers have become active and have achieved rapid growth. As the price has increased, full-color printing has become easier. In a full-color copying machine such as a copying machine or a printer, an image is formed using four color toners.
The size is reduced to μm. However, when a conventional monochrome recording paper is printed by an electrophotographic full-color image forming apparatus, these papers have a low density,
Since the space between the fibers in the surface layer of the paper was large, the toner dropped into the space between the fibers during transfer, and a decrease in the density in terms of image quality was observed. Furthermore, when a full-color image having a high image density is printed using these papers, or when two-sided copying is performed, a problem of show-through occurs. In addition, since the surface of these papers is roughly adjusted, there are problems such as mottle (fine unevenness in density of an image) and graininess (roughness of an image).

In order to solve these problems, for example, as described in JP-A-5-341553, the surface of a paper is highly smoothed and the density is increased to 0.80 g / cm ³ or more to improve toner transferability. To achieve high image quality. Further, in the full-color image forming apparatus, since the amount of heat necessary to fix the toners of four colors is applied, the monochrome image forming apparatus fixes the toner with one heating roll, whereas the full-color image forming apparatus fixes two toners. Japanese Patent Application Laid-Open No. 5-34 discloses fixing a toner with a heating roll.
In the method described in Japanese Patent No. 1553, it is necessary to increase the grammage as high as 75 to 95 g / m ^{2 in} order to obtain the stiffness of the paper required for the running property in the full-color image forming apparatus. Therefore, in the method described in Japanese Patent Application Laid-Open No. Hei 5-341553, the production cost is increased because a larger amount of pulp material is used as compared with monochrome recording paper used in general offices and the like. For example, when a book is used in combination with a recording paper, the book has a problem that it is difficult to handle as a book due to a sense of incongruity caused by a difference in paper weight and stiffness.

On the other hand, for a full-color image forming apparatus, Japanese Patent Application Laid-Open Nos.
No. 98877, JP-A-3-294600, JP-A-Hei-4
JP-A-291351, JP-A-8-1230065, JP-A-8-123066, JP-A-8-171
The coated paper type recording paper described in Japanese Patent Publication No. 226 is mainly used, but the coated paper type recording paper has a problem that the writing property is too poor because the coating layer strength and the smoothness are increased. In addition, coated paper is expensive and cannot be used in the same way as monochrome recording paper in offices or personal offices, so it is necessary to replace the paper in the image printing device each time a full-color original is output. The user has to prepare and use the corresponding recording paper, which is very troublesome in terms of convenience and inventory management. Therefore, it is very difficult to solve this problem by the conventional technique, and no effective means has been disclosed yet.

[0005]

In view of the above-mentioned problems in the prior art, even when used in a copying machine or a printer using a toner having a reduced particle size, good print density and uniformity of density can be obtained. An object of the present invention is to provide a non-coated type information recording sheet which is as low in cost as monochromatic paper and which can provide image quality and running properties.

[0006]

Means for Solving the Problems The present inventors have succeeded in solving the above problems by employing the following constitution. That is, on at least one surface of the paper, the average circle-equivalent diameter of the void portion in the surface layer of the paper is 10 μm.
It is characterized in that the void portion of m or more is 30% or less, and the surface coating layer is applied in a range of 0.5 to 2.0 g / m ² .

The present inventors have conducted intensive studies to solve these problems caused by the image quality, and as a result, as shown in FIG. 1, found the relationship between the porosity between fibers present in the surface layer of the paper and the print density. Was. Here, the porosity existing in the surface layer of the paper indicates a void existing between fibers measured by the following method. Porosity of the paper surface layer: 300 × magnification of the paper surface with an electron microscope
(See FIGS. 2 to 5) taken with the image analyzer DA-50
Binarization was performed using 00 (manufactured by Oji Scientific Instruments). Voids were extracted from the binarized image, and the ratio of the voids having an equivalent circle diameter of 10 μm or more was calculated. Note that there is no direct relationship between the air permeability and the porosity of the paper surface, but the image quality and the like are more affected by the surface properties. Further, even paper having the same degree of air permeability has different image quality due to a difference in surface properties. In order to improve the porosity between the fibers, a study was conducted by increasing the density of the paper, which is known as a conventional solution. However, when the basis weight of the paper is kept constant and the density is increased, the stiffness decreases. Although the printing density in a copier or a printer is improved, there is a problem that the stiffness of the paper deteriorates and the running property is deteriorated, so that an appropriate solution cannot be found. For further study, we investigated the particle size of the toner used in copiers and printers and the behavior of the toner on the paper surface during transfer, and found that the density of the paper was reduced by providing a surface coating layer on the paper surface. It has been found that the toner having a reduced particle diameter suppresses the fiber from dropping into the voids without increasing more than necessary.

The specific structure of the present invention is as follows. In order to adjust the porosity of the paper surface layer, it is necessary to adjust the density described in JIS P-8118 in the range of 0.73 to 0.80 g / cm ³ . If the density is 0.73 g / cm ³ or less, the desired porosity cannot be obtained, and the toner falls into the gap between the fibers during transfer, causing a decrease in density and a deterioration in density uniformity in terms of image quality. I will. In addition, the density is 0.80
If it is at least g / cm ³ , the thickness will be thin, and as described above, the required stiffness for running properties will be reduced, and problems will occur such as causing paper jams in the fixing section and worsening running properties. . In order to suppress this, an increase in the basis weight or the addition of a paper strength enhancer can be mentioned, but in any case, the cost becomes high and the cost becomes close to that of a full-color dedicated paper.

[0009] surface coating layer is preferably applied in at least one side of 0.5 to 2.0 g / ^{m 2} range of the paper, the surface coating layer is 0.5 g / ^{m 2} or less toner It falls into the gaps between the fibers, lowering the density and deteriorating the uniformity of the image quality, so that the desired effect cannot be exhibited. Further, when the surface coating layer is 2.0 g / m ² or more, coating unevenness is likely to occur on the production side, causing paper breakage, and furthermore, contamination in the paper machine system and stable production becomes difficult. . In addition, there is a problem in that, when the product is finished, blocking is caused and a paper jam occurs in a sheet feeding unit in the image forming apparatus.

Examples of the material used for the surface coating layer include synthetic polymers such as polyvinyl alcohol and polyacrylamide, and natural polymers such as starch, oxidized starch and modified starch. Polyvinyl alcohol is preferred from the viewpoint of film properties, surface sizing properties, and the like,
Furthermore, the degree of polymerization of polyvinyl alcohol is 1,000
It is preferable to adjust the range to 2,500. If the degree of polymerization is less than 1,000, the solution viscosity decreases and the yield of polyvinyl alcohol on the paper surface is extremely reduced, so that the desired effect cannot be exhibited. Further, the degree of polymerization is 2,500.
If it is above, there is a problem that the viscosity becomes high and stable production cannot be performed in operation. The above-mentioned resins can be applied by a general coating method such as size press coating or gate roll coating. These resins are used in addition to surface sizing agents such as oxidized starch, modified starch, acrylic and styrene, and sodium chloride, potassium chloride, polyethylene sulfonate, and acrylic sulphate to prevent background staining in electrophotography. Even when used in combination with a conductive agent such as a quaternary ammonium salt, sodium sulfate or sodium carbonate, it can be used without any problem.

The internal sizing agent used in the present invention is a rosin sizing agent, a synthetic sizing agent, a petroleum resin sizing agent,
Although a sizing agent such as a neutral sizing agent can be used, it is preferable to use a neutral sizing agent from the viewpoints of running properties and image quality in a copying machine or a printer using an electrophotographic system, and paper storability. Further, from the viewpoint of suppressing the toner from dropping into the voids between the fibers, the drop of the toner can be further suppressed by increasing the inter-fiber bonding inside the paper layer. Polyacrylamides (anionic, cationic, amphoteric),
Examples include methylolated polyacrylamide, epoxidized polyamide resin, polyethyleneimine, carboxymethylcellulose, polyvinyl alcohol, cationized starch, carboxymethylated starch, oxidized starch, urea-formaldehyde resin, and melamine-formaldehyde resin. The addition amount of the paper strength enhancer is 0.01 to 1.0% by weight,
More preferably, it is added in the range of 0.05 to 0.5% by weight. If the addition amount exceeds 1.0% by weight, coating irregularities are likely to occur on the production side, causing breakage of the paper, or leading to contamination in the paper machine system, resulting in production problems. Furthermore, flocs (lumps of fibers) are likely to occur, which has an adverse effect such as deterioration of formation.

The pulp used in the present invention is LBK.
P (hardwood bleached kraft pulp), NBKP (softwood bleached kraft pulp), LBSP (hardwood bleached sulphite pulp),
Chemical pulp such as NBSP (softwood bleached sulfite pulp) can be used. However, NBKP and NBS
When softwood pulp such as P is used, the fibers are longer and thicker than LBKP or the like, so the gap between the fibers on the paper surface layer is likely to be large. Since it is likely to occur, it is necessary to mix in consideration of formation. In addition, high-quality waste paper mainly made of high-quality paper generated in offices and the like, and waste paper generated from white unprinted high-quality paper such as white, special white, medium white, and white spots generated in printing and cutting shops, etc. Can be used. When paper is made from the above pulp raw material, it is preferable to adjust the uniform formation from the viewpoint of image quality in a full-color image forming apparatus. If the formation is non-uniform, the difference between the high (flocked) and low (non-flocked) parts of the basis weight in a single sheet increases, making it possible to use a full-color image printing device that uses the electrophotographic method. At the time of recording, a difference occurs in the transferability between the flocked portion and the non-floc portion, so that there arises a problem that the mottle (fine unevenness in density) and the graininess (roughness of the image) are deteriorated.

As the calcium carbonate used in the present invention, both heavy calcium carbonate and light calcium carbonate can be used. The blending ratio of calcium carbonate is preferably from 10 to 20% by weight from the viewpoint of show-through and running properties. When the mixing ratio of calcium carbonate is more than 20% by weight, the opacity is improved and the show-through is greatly suppressed, but on the other hand, the bonding between fibers is reduced and paper powder is easily generated, so that the inside of the image forming apparatus is reduced. Contamination leads to deterioration of image quality, and furthermore, adheres to a member of a paper feeding unit, causing problems such as poor paper feeding. Also, if the compounding ratio of calcium carbonate is less than 10% by weight,
The opacity is reduced, and especially when a full-color image with a high image density is printed, show-through is noticeable, and information under the back surface of the sheet becomes visible, so that the information on the sheet becomes difficult to read.

The smoothness of the paper whose formation has been adjusted by using the pulp and the filler is determined by a calendering treatment or the like with an Oken-type smoothness tester for 40 to 90 seconds, preferably 50 to 80 seconds.
It is preferable to adjust the range to seconds. If the smoothness is less than 40 seconds, the surface of the paper becomes rough and a difference occurs in the transferability between the concave portion and the convex portion when printing with an electrophotographic image forming apparatus, so that mottle and graininess deteriorate. Occurs. Further, when the smoothness is 90 seconds or more, the surface of the paper becomes smooth, and the transferability when recording with an electrophotographic full-color image forming apparatus is improved. Adhesion between them increases, and the coefficient of friction increases, resulting in poor sheet feeding.

When the smoothness is adjusted by the calender to 40 to 90 seconds, the density of the paper is 0.73 to 0.73 from the viewpoint of maintaining image quality and stiffness required for running characteristics.
It is preferably adjusted to 0.80 g / cm ³ . Density is 0.
If the amount is less than 73 g / cm ³ , the toner drops into the gap between the fibers during transfer, causing a decrease in density and a deterioration in density uniformity in terms of image quality. On the other hand, if the density is more than 80 g / cm ³ , the thickness becomes thin, the stiffness is reduced, and a paper jam occurs in the fixing portion, thereby causing problems such as deterioration of running performance. In order to suppress this, an increase in the basis weight or the addition of a paper strength enhancer can be mentioned, but in any case, the cost becomes high, and the cost becomes close to that of a full-color paper.

[0016]

EXAMPLES The present invention will be described in more detail with reference to the following examples, which, of course, are not intended to limit the scope of the present invention. Table 1 collectively shows the following Examples 1 to 5 for easy understanding.

[0017]

[Table 1]

(Example 1) As shown in Example 1 of Table 1,
LBKP (hardwood bleached kraft pulp) as pulp material
100% used. 450ml CS using this pulp
F. (Canadian Standard Freeness), beaten with 10% by weight of light calcium carbonate as a filler, and 0.05 g / m ² of alkenyl succinic anhydride (ASA) as an internal sizing agent.
And 0.5% by weight as a paper-strength enhancer to improve the solid concentration. The paper material was used to make paper at a speed of 700 m / min using an on-top twin wire, and dewatered from both sides to form a paper layer. To provide a coating layer, polyvinyl alcohol (PVA) was combined with 0.3 g / m ² per one side and oxidized starch 0.2 g / m ² to form a 0.5 g / m ² coating layer. To impart suitability, a mixture of sodium chloride at 0.2 g / m ² was applied by a size press recipe. The transfer paper obtained at this time was a transfer paper of the present invention having a basis weight of 65 g / m ² , a thickness of 89 μm, and a density of 0.73 g / m ² . As a result of measuring the porosity of each of the front and back sides of the transfer paper by the above method, F
S: 28%, WS: 30%. The image quality and runnability of the transfer paper in color copy were confirmed as follows. That is, the transfer paper is transferred to a color copier (Fuji Xerox: Color Laser Wind 332).
0) using yellow, magenta, cyan, red,
A solid patch (2.5 × 2.5 cm) having an image area ratio of 100% for green, blue, and a mixed color black of yellow, magenta, and cyan was transferred to this transfer sheet and fixed. The toner used in this color copying machine has an average particle diameter of 7 μm. Table 1 shows the results. As is clear from Table 1, the porosity of the paper surface layer was FS: 28%,
WS: The effect of providing a coating layer of 30%, 0.5 g / m ² per side is that even if a toner having an average particle diameter of 7 μm is used, the solid density is high and images such as mottle and graininess are high. Good results were also obtained in terms of quality, and good information recording paper was also obtained in terms of runnability.

Example 2 As shown in Example 2 of Table 1,
High quality waste paper DIP 100% was used as a pulp material. This pulp is beaten to 450 ml CSF (Canadian standard freeness), and light calcium carbonate is added as a filler.
0% by weight, and 0.05 g / m ² of a neutral rosin sizing agent was added to the internal sizing agent. A paper layer was formed by using this paper material with an on-top twin wire at a paper making speed of 700 m / min, and dewatering from both sides. To this, polyacrylamide (PAM) was added at a rate of 0.1% per side to provide a coating layer.
5 g / m ² , 0.5 g / m ² of oxidized starch and 1.0 g / m ²
An m ² coating film layer was further applied by a size press formulation to which 0.2 g / m ^{2 of} sodium chloride was mixed in order to impart xerographic aptitude. The transfer paper obtained at this time had a basis weight of 70 g / m ² , a thickness of 93 μm, and a density of 0.75 g / m ² .
^Thus , No. ² information recording paper of the present invention was obtained. As a result of measuring the porosity of each of the front and back sides of this paper by the above-described method, FS: 24%, W
S: 26%. The image quality and runnability of the information recording paper in a color copy were confirmed as follows. That is, this information recording paper is image area ratio of yellow, magenta, cyan, red, green, blue and a mixed color black of yellow, magenta, and cyan by using a color copier (Color Laser Wind 3320, manufactured by Fuji Xerox Co., Ltd.). 100% solid patch (2.5x
2.5 cm) was transferred and fixed on this sheet. The toner used in this color copying machine has an average particle diameter of 7 μm. Table 1 shows the results. As is clear from Table 1,
The effect of providing a coating layer having a porosity of FS: 24%, WS: 26%, and 1.0 g / m ² per side on the surface layer of the paper is as follows. High density, good results in image quality such as mottle and graininess, and good information recording paper in running property were obtained.

Example 3 As shown in Example 3 of Table 1,
LBKP (hardwood bleached kraft pulp) as pulp material
100% used. 450ml CS using this pulp
F. (Canadian Standard Freeness), beaten with 15% by weight of light calcium carbonate as a filler, and 0.05 g / m ² of alkenyl succinic anhydride (ASA) as an internal sizing agent.
Was blended. A paper layer was formed by using this paper material with an on-top twin wire at a paper making speed of 700 m / min, and dewatering from both sides. This, per side 1.0 g / ^{m 2} of polyvinyl alcohol (PVA) to provide a coating layer, the oxidized starch and a coating layer of 2.0 g / ^{m 2} combined 1.0 g / ^{m 2,} further xerographic To impart suitability, a mixture of sodium chloride at 0.2 g / m ² was applied by a size press recipe. The paper obtained at this time has a basis weight of 72 g /
m ² , a thickness of 95 μm, and a density of 0.76 g / m ² of the present invention were obtained. The porosity of each of the front and back sides of this paper was measured by the above method, and as a result, FS was 20% and WS was 21%. The image quality and runnability of this transfer paper in color copy were confirmed as follows. That is, this information recording paper is transferred to a color copier (Fuji Xerox Co., Ltd .: Co
lor Laser Wind 3320) using yellow, magenta, cyan, red, green, blue and yellow,
Image area ratio 1 for mixed color black of magenta and cyan
A 00% solid patch (2.5 × 2.5 cm) was transferred and fixed on this information recording paper. The toner used in this color copying machine has an average particle diameter of 7 μm. Table 1 shows the results. As is clear from Table 1, the porosity of the paper surface layer was FS: 20%, WS: 21%, and 2.0 per side.
As a result of providing a coating layer of 0 g / m ² , even when a toner having an average particle diameter of 7 μm is used, the solid density is high, and good results are obtained in image quality such as mottle and granularity. Good information recording paper was also obtained in terms of runnability.

Example 4 As shown in Example 4 of Table 1,
As the pulp material, 70% of high quality waste paper DIP and 30% of LBKP (hardwood bleached kraft pulp) were used. This pulp is beaten to 450 ml CSF (Canada standard freeness), 20% by weight of light calcium carbonate is added as a filler, and an alkyl ketene dimer (AK) is used as an internal sizing agent.
D) 0.05 g / m ^{2 was} blended. A paper layer was formed by using this paper material with an on-top twin wire at a paper making speed of 700 m / min, and dewatering from both sides. To provide a coating layer, polyacrylamide (PAM) was combined with 0.75 g / m ² per one side and oxidized starch 0.75 g / m ² to form a 1.5 g / m ² coating layer. To impart suitability, a mixture of sodium chloride at 0.2 g / m ² was applied by a size press recipe. Information recording sheets obtained at this time was obtained basis weight 72 g / ^{m 2,} thickness 92 [mu] m, a density of 0.78 g / ^{m 2} of the present invention the information recording paper. As a result of measuring the porosity of each of the front and back sides of this information recording paper by the above method, FS was 15% and WS was 15%. The image quality and runnability of the information recording paper in a color copy were confirmed as follows. That is, this information recording paper is transferred to a color copier (Fuji Xerox: Color Laser).
Wind 3320) using yellow, magenta, cyan,
A solid patch (2.5 × 2.5 cm) having an image area ratio of 100% for a mixed color black of red, green and blue and yellow, magenta and cyan was transferred and fixed on this information recording paper. The toner used in this color copying machine has an average particle diameter of 7 μm. Table 1 shows the results. As is clear from Table 1, the porosity of the paper surface layer is
S: 15%, WS: 15%, 1.5 g / m ² per side
The effect of providing the coating layer of the above is that the average particle diameter of the toner is 7
Even with the use of μm, the solid density is high and good results are obtained in image quality such as mottle and graininess.
Good information recording paper was also obtained in terms of runnability.

(Example 5) As shown in Example 4 of Table 1,
LBKP (hardwood bleached kraft pulp) as pulp material
100% used. 450ml CS using this pulp
F. (Canadian Standard Freeness), beaten with 10% by weight of light calcium carbonate as a filler, and 0.05 g / m ² of alkenyl succinic anhydride (ASA) as an internal sizing agent.
Was blended. A paper layer was formed by using this paper material with an on-top twin wire at a paper making speed of 700 m / min, and dewatering from both sides. This, per side 0.3 g / ^{m 2} of polyvinyl alcohol (PVA) to provide a coating layer, the oxidized starch and a coating layer of 0.6 g / ^{m 2} combined 0.3 g / ^{m 2,} further xerographic To impart suitability, a mixture of sodium chloride at 0.2 g / m ² was applied by a size press recipe. The transfer paper obtained at this time has a basis weight of 73 g /
m ² , a thickness of 91 μm, and a density of 0.80 g / m ² of the present invention were obtained. The porosity of each of the front and back sides of this paper was measured by the above method, and as a result, FS was 9% and WS was 10%. The image quality and runnability of the information recording paper in a color copy were confirmed as follows. That is, this information recording paper is transferred to a color copier (Fuji Xerox:
Color Laser Wind 3320) using yellow, magenta, cyan, red, green, blue and yellow,
Image area ratio 1 for mixed color black of magenta and cyan
A 00% solid patch (2.5 × 2.5 cm) was transferred and fixed on this information recording paper. The toner used in this color copying machine has an average particle diameter of 7 μm. Table 1 shows the results. As is apparent from Table 1, the porosity of the surface layer of the paper was FS: 9%, WS: 10%, and 0.6 per side.
As an effect of providing a coating layer of g / m ² , even when a toner having an average particle diameter of 7 μm is used, the solid density is high, and good results are obtained in image quality such as mottle and granularity. Good information recording paper was also obtained in terms of runnability. Table 2 summarizes Comparative Examples 1 to 3.

[0023]

[Table 2]

Comparative Example 1 As shown in Comparative Example 1 in Table 2,
As in Example 1, 100% LBKP (hardwood bleached kraft pulp) was used as a pulp material. Using this pulp, beat to 450 ml CSF (Canadian Standard Freeness), add 5% by weight of light calcium carbonate as filler,
Alkenyl succinic anhydride (ASA)
0.05 g / m ^{2 was} blended. A paper layer was formed by using this paper material with an on-top twin wire at a paper making speed of 700 m / min, and dewatering from both sides. Furthermore per side starch 0.3 g / m ² for imparting xerographic suitability ^and those sodium chloride 0.2 g / m ² were mixed was applied with a size press formulation. Information recording sheets obtained at this time was obtained basis weight 65 g / ^{m 2,} a thickness of 95 .mu.m, the present invention transfer paper of density 0.68 g / ^{m 2.} As a result of measuring the porosity of each of the front and back sides of this information recording paper by the above method, FS: 36%, W
S: 41%. The image quality and running property of this information recording paper were confirmed by the same experimental method as in Example 1. Table 2 shows the results.

(Comparative Example 2) Fine waste paper D as a pulp material
IP 100% was used. 450ml using this pulp
It was beaten to CSF (Canadian Standard Freeness), 5% by weight of light calcium carbonate was added as a filler, and 0.05 g / m ² of a neutral rosin sizing agent was added to the internal sizing agent. Using this stock, on-top twin wire machine 700
Paper was formed at m / min., and dewatered from both sides to form a paper layer. Furthermore per side starch 0.3 g / m ² for imparting xerographic suitability ^and those sodium chloride 0.2 g / m ² were mixed was applied with a size press formulation. The paper obtained at this time was an information recording paper of the present invention having a basis weight of 70 g / m ² , a thickness of 85 μm, and a density of 0.82 g / m ² . The porosity of each of the front and back sides of this information recording information recording paper was measured by the above method, and as a result, FS was 8% and WS was 8%. The image quality and running property of this information recording paper were confirmed by the same experimental method as in Example 1. Table 2 shows the results.

(Comparative Example 3) Fine waste paper D as a pulp material
IP70%, LBKP (hardwood bleached kraft pulp) 30
%used. The pulp was beaten to 450 ml CSF (Canada Standard Freeness), 20% by weight of light calcium carbonate was added as a filler, and 0.05 g / m ² of alkyl ketene dimer (AKD) was added to the internal sizing agent. A paper layer was formed by using this paper material with an on-top twin wire at a paper making speed of 700 m / min, and dewatering from both sides. Per side starch 0.3 g / ^{m 2} for further imparting xerographic suitability, sodium chloride 0.2 g / ^{m 2}
The mixture was applied by a size press recipe. The transfer paper obtained at this time had a basis weight of 80 g / m ² and a thickness of 92 μm.
m and a density of 0.87 g / m ² of the present invention were obtained. As a result of measuring the porosity of each of the front and back sides of this transfer sheet by the above-described method, FS was 7% and WS was 6%. The image quality and running property of this information recording paper were confirmed by the same experimental method as in Example 1. Table 2 shows the results.

[0027]

According to the information recording paper of the present invention, the porosity in the surface layer of the paper is at least 30 on at least one surface of the paper.
% Or less, and an electrophotographic copying machine using a toner having a reduced particle size in order to apply the surface coating layer in a range of 0.5 to 2.0 g / m ² . When transferred by a printer, image quality characteristics are superior to conventional paper, in that toner is prevented from falling into voids between fibers on the surface of the paper, and printing density and density uniformity are improved while avoiding high basis weight. And driving characteristics can be achieved.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the porosity between fibers present on the surface layer of paper and the print density.

FIG. 2 is an enlarged (300 ×) photograph of the surface of a sheet.

FIG. 3 is an enlarged (300 ×) photograph of the surface of a sheet.

FIG. 4 is an enlarged (300 ×) photograph of the surface of a sheet.

FIG. 5 is an enlarged (300 ×) photograph of the surface of a sheet.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hiromi Ishida 2-5-112 Kanda Surugadai, Chiyoda-ku, Tokyo Fuji Xerox Office Supply Co., Ltd. In-house F-term (reference) 4L055 AG07 AG48 AG72 BE08 EA14 EA18 FA15 FA30 GA11

Claims (2)

[Claims] 1. An information recording sheet characterized in that, on at least one surface of the sheet, a void ratio in a surface portion of the sheet having an equivalent circle diameter of 10 μm or more is 30% or less. 2. A coating film layer having a thickness of 0.5 to 2.0 g /
Information recording sheet according to claim 1, characterized in that applied in the range of m ^2.