JP2008020539A - Recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a recording medium which suppresses transfer missing caused by a magnetic material incorporated in a paper sheet when an image is formed by an electrographic process. <P>SOLUTION: The recording medium contains a magnetic material, and is characterized in that the center line average roughness Ra is ≤3.0 μm, and the maximum value of the maximum height Rmax is ≤80 μm in the circumference of at least one side of the part where the magnetic material is blended. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a recording medium including a magnetic material that can be printed with a general recording material such as toner or ink, and that can record and reproduce information by magnetic means.

  For special documents (special documents) such as banknotes and securities, it is extremely important to prevent forgery. In order to prevent forgery in such a special document, a technique for inserting or embedding a metal fiber made of a magnetic material or the like that can be detected by a magnetic means in the special document has been conventionally known (Patent Document 1, (See 2nd grade).

  On the other hand, in recent years, with the spread of computers, multifunction peripherals, and networks, it has become possible to easily acquire desired information from a vast amount of information, and to print and copy the acquired information. For this reason, the problem that confidential information is leaked by taking out a printed matter in which highly confidential information is illegally copied or printed is being highlighted. In view of this, various apparatuses and methods have been proposed in which security of information is enhanced in order to prevent leakage of confidential information caused by taking out a printed matter in which highly confidential information is illegally copied or printed.

For example, by using a combination of a printing paper containing a magnetic material capable of recording unique identification information and an information reading device that reads the identification information and determines the validity of the information printed on the printing paper. A method for enhancing the security of information has been proposed (see Patent Documents 3 and 4).
JP 10-143708 A JP-A-7-32778 JP 2004-284053 A JP 2004-285524 A

In special documents and printing papers used to prevent forgery as described above, metal fibers such as magnetic materials are embedded or embedded in the papers. Since there is no chemical bond between the magnetic material and the pulp fiber, the moisture content in the paper changes, especially in the periphery where the magnetic material is contained during drying, the pulp fiber shrinks unevenly, and the paper surface Of these, irregular shapes occur. Such a corrugated shape of the wave has a problem that a printing paper used for image formation causes a transfer omission when an image is formed by an electrophotographic method.
An object of the present invention is to solve the above problems. That is, the present invention is a recording medium that suppresses transfer omission due to a magnetic material contained in a sheet and forms an image quality similar to that of a conventional electrophotographic transfer sheet when an image is formed by electrophotography. It is an issue to provide.

The above object is achieved by the present invention described below. That is, the present invention
<1>
A recording comprising a magnetic material, wherein at least one surface of the magnetic material blending part has a center line average roughness Ra of 3.0 μm or less and a maximum height Rmax of 80 μm or less. It is a medium.

<2>
<1> The recording medium according to <1>, wherein the magnetic material causes at least a large Barkhausen effect.

  As described above, according to the present invention, when an image is formed by electrophotography, transfer omission caused by the magnetic material contained in the paper is suppressed, and the same as that of a conventional electrophotographic transfer paper. A recording medium capable of obtaining image quality can be provided.

The recording medium of the present invention includes a magnetic material, and has a center line average roughness Ra of 3.0 μm or less and a maximum value of the maximum height Rmax of 80 μm or less at least around the magnetic material blending portion on one side. It is characterized by being.
Therefore, even if an image is formed by electrophotography using the recording medium of the present invention, it is possible to suppress the occurrence of transfer omission and to obtain the same image quality as that of a conventional electrophotographic transfer paper. it can.
Therefore, the recording medium of the present invention can be preferably used as an electrophotographic transfer paper because the occurrence of transfer omission can be suppressed, but is not limited to this, and can be used in a known recording method. It can also be used as an inkjet recording paper.

  Note that transfer omission occurs when the surface of the electrophotographic transfer paper becomes rough and the toner image held on the surface of the photoreceptor (or the surface of the intermediate transfer body such as an intermediate transfer belt) is transferred to the paper surface. Since a gap is likely to be partially generated between the surface of the sheet and the surface of the photosensitive member (or intermediate transfer member) that are in contact with each other, the toner may not be transferred at the gap. Are known.

On the other hand, centerline average roughness Ra is usually used as an index representing the surface roughness of paper, and Ra on the surface of paper commercially available as electrophotographic transfer paper is, for example, P paper (Fuji Xerox Corporation). It is 2.1 μm for the company's product and 2.3 μm for the OK Prince fine quality (manufactured by Oji Paper Co., Ltd.).
However, as a result of intensive studies by the present inventors, transfer omission occurs even in paper containing a magnetic material in which Ra on the surface of the paper is adjusted to the same level as a commercially available electrophotographic transfer paper. It was confirmed that it occurred around the club. Further, when the portion where the transfer omission occurred was observed, the corrugated shape was present. Therefore, the uneven shape of the waves causes a gap between the surface of the photosensitive member (or intermediate transfer member) that is in contact with the paper surface and the surface of the paper at the time of transfer, thereby causing transfer omission. It is thought that there is.

  In addition, it is thought that an uneven | corrugated shape is generated for the following reasons. That is, since no chemical bond (hydrogen bond) is formed between the magnetic material and the pulp fibers contained in the paper, the shrinkage unevenness of the pulp fibers existing around the magnetic material due to a change in the amount of water contained in the paper is caused. Will occur. This shrinkage unevenness is considered to cause continuously repeated unevenness (unevenness shape of the wave) on the surface of the paper.

Based on the knowledge as described above, the present inventors have found that the occurrence of transfer omission can be suppressed if the maximum value of the maximum height Rmax around the magnetic material blending portion is 80 μm or less.
Note that the maximum value of the maximum height Rmax is preferably 60 μm or less, more preferably 50 μm or less, and the closer to 0 μm, the better. When the maximum height exceeds 80 μm, a gap is partially generated between the surface of the recording medium and the surface of the photosensitive member (or intermediate transfer member) that are in contact with each other at the transfer portion, and transfer omission occurs. Will occur.
It is particularly preferable that the maximum value of Rmax described above is satisfied on both sides of the recording medium. Thereby, even if an image is formed on the front or back surface of the recording medium by electrophotography, the occurrence of transfer omission can be suppressed.

  In the present invention, the maximum height Rmax is measured according to JIS B 0651, and a surface roughness measuring machine (Surfcoder SE-30K Kosaka Co., Ltd.) is used around the magnetic material blending portion on the surface of the recording medium. Means a value obtained by measuring the surface roughness along the axial direction of the magnetic material. For the recording medium, the maximum height Rmax was measured for the entire area around the magnetic material blending portion. Then, the maximum value of the maximum height Rmax at each of these measurement points was obtained.

Next, details of the measurement of the maximum height Rmax around each magnetic material blending portion will be described below.
FIG. 1 is a schematic diagram for explaining a method of measuring the maximum height Rmax, and shows an arrangement state of magnetic materials contained in the recording medium in the plane direction of the recording medium. The shape of the magnetic material used in the present invention is not particularly limited, but a linear magnetic material having a length of several millimeters or more (hereinafter may be referred to as “magnetic wire”) is preferably used. 1 shows the case where the magnetic material is linear.
In FIG. 1, 10 represents a magnetic wire, 20 represents a measurement area, and FIG. 1A illustrates a measurement area when the magnetic wire is arranged linearly with respect to the recording medium plane direction. FIG. 1B shows a measurement area when the magnetic wire is arranged so as to meander with respect to the plane direction of the recording medium. As shown in FIG. 1, the measurement area 20 is set along the axial direction of the magnetic wire 10, and when the magnetic wire 10 is meandering as shown in FIG. The measurement area 20 was set for each change in the direction in which the magnetic wire 10 meanders.
Here, the measurement of the maximum height Rmax was carried out under the following conditions for the recording medium after being conditioned for 12 hours or more in an environment of a temperature of 23 ° C. and a humidity of 50%.
<Measurement conditions>
X-axis measurement length: 10 mm X-axis recording pitch: 20 μm X-axis feed speed: 2 mm / s
Y-axis recording limit: 180 mm Y-axis recording pitch: 1 mm Y-axis feed pitch: 2 μm
Vertical magnification: 200 times Horizontal magnification: 20 times Low frequency cutoff: R + W High frequency cutoff: 0.8 mm

The recording medium of the present invention has a center line average roughness measured in accordance with JIS B 0651 on at least one side (the surface on the side where the maximum value of the maximum height Rmax around the magnetic material blending portion is 80 μm or less). Ra needs to be 3.0 μm or less, and it is particularly preferable that both surfaces are 3.0 μm or less.
In the case where there is an uneven shape of the wave measured as the maximum height Rmax or other large surface unevenness (for example, the rise of the surface of the recording medium due to the presence of the magnetic material itself), the magnetic material blending portion The influence of these surface irregularities may be reflected in Ra obtained by measuring the periphery.
Therefore, even if the maximum value of the maximum height Rmax is 80 μm or less, when Ra exceeds 3.0 μm, there may be other large surface unevenness in addition to the uneven shape of the wave. In addition, when such other large surface irregularities do not exist, it is considered that the roughness itself of the recording medium surface is increased as in the case where Ra is large in the conventional electrophotographic transfer paper. Therefore, in the former case, transfer omission occurs, and in the latter case, the image quality (transferability and graininess) deteriorates.
Therefore, if the maximum value of the maximum height Rmax is 80 μm or less and Ra is 3.0 μm or less, the occurrence of transfer omission can be suppressed and the image quality (transferability, Granularity) can be obtained. Note that Ra is preferably 2.8 μm or less, and more preferably 2.5 μm or less.

In the present invention, the centerline average roughness Ra is measured using a three-dimensional surface roughness measuring machine (Surfcoder SE-30K manufactured by Kosaka Laboratory Ltd.) in accordance with JIS B 0651, and Rmax is After setting the location where Ra was measured so that the measured location was located in the center, the location was measured, and the average value of Ra at each measurement point was determined.
Here, the measurement of the center line average roughness Ra was carried out under the following conditions for the recording medium after being conditioned for 12 hours or more in an environment of a temperature of 23 ° C. and a humidity of 50%.
<Measurement conditions>
X-axis measurement length: 40 mm X-axis recording pitch: 80 μm X-axis feed speed: 2 mm / s
Y-axis recording limit: 180 mm Y-axis recording pitch: 2 mm Y-axis feed pitch: 100 μm
Vertical magnification: 200 times Horizontal magnification: 5 times Low frequency cut-off: 0.8 mm High frequency cut-off: R + W

Next, the constituent material, manufacturing method, various physical properties and the like of the recording medium of the present invention will be described in detail.
-Magnetic material-
The magnetic material contained in the recording medium of the present invention is particularly preferably one that causes a large Barkhausen effect. Here, the large Barkhausen effect will be briefly described. FIG. 2 is a diagram for explaining the large Barkhausen effect. The large Barkhausen effect has a BH characteristic as shown in FIG. 2A, that is, a material having a relatively small hysteresis loop and a relatively small coercive force (Hc), for example, Co—Fe—Ni—B—. This is a phenomenon in which sharp magnetization reversal occurs when an amorphous magnetic material made of Si is placed in an alternating magnetic field. For this reason, if an alternating current is passed through the exciting coil to generate an alternating magnetic field, and a magnetic material is placed in the alternating magnetic field, a pulsed current will flow through the sensing coil placed near the magnetic material during magnetization reversal. Become.

  For example, when an alternating magnetic field as shown in the upper part of FIG. 2B is generated by the exciting coil, a pulse current as shown in the lower part of FIG. 2B flows through the detection coil.

  However, an alternating current induced by an alternating magnetic field also flows in the current flowing through the detection coil, and the pulse current is detected by being superimposed on the alternating current. In addition, when a material including a plurality of magnetic materials is placed in an alternating magnetic field, a plurality of pulse currents are superimposed, and a current as shown in FIG. 2C is detected.

The magnetic material contained in the recording medium of the present invention is generally a permanent magnet, for example, a rare earth based neodymium (Nd) -iron (Fe) -boron (B) as a main component, samarium (Sm). -Cobalt (Co) as the main component, Alnico-based aluminum (Al) -Nickel (Ni) -Cobalt (Co) as the main component, Ferrite-based barium (Ba) or Strontium (Sr) and oxidation Amorphous magnets that have iron (Fe ₂ O ₃ ) as the main component, soft magnetic materials, oxide soft magnetic materials, etc., but whose basic composition is Fe-Co-Si or Co-Fe-Ni system It is preferable to use a material.

  The shape of the magnetic material is not particularly limited as long as it is a vertically long shape (linear shape) suitable for causing the large Barkhausen effect, but in order to cause the large Barkhausen effect, a predetermined length with respect to the cross-sectional area is required. Therefore, basically, a wire shape or a belt shape is preferable, and a wire shape is more preferable.

  When the magnetic material is in the form of a wire, the diameter is preferably 10 μm or more in order to cause a large Barkhausen effect as described above. Further, the maximum diameter is not particularly limited, but the diameter depends on the thickness of the paper in order to prevent the magnetic wire from being exposed on the paper surface. For example, in the case of a paper having a thickness of about 90 μm. 60 μm or less is preferable, and 50 μm or less is more preferable.

The length of the magnetic wire is preferably 10 mm or more in order to cause a large Barkhausen effect. The maximum length of the magnetic wire is not particularly limited as long as it is not exposed from the recording medium when it is contained inside, but is preferably 430 mm or less.
Note that the diameter and length of the magnetic wire rods preferably satisfy the above-mentioned ranges for all the magnetic wire rods contained in the recording medium. It is preferable to satisfy the above-described range.

  The recording medium of the present invention contains pulp fibers as the main component in addition to the magnetic material, and various materials used for ordinary paper media as necessary. Further, the layer structure of the recording medium of the present invention is not particularly limited, but it may have at least a paper base material containing pulp fibers as a main component, and the paper base material may have a multilayer structure of two or more layers. . The magnetic material may be present at any position in the recording medium, but basically it is particularly preferably contained in the paper base material. In the following description, the magnetic material is contained in the paper base material. It is assumed that it is included.

The method for controlling the maximum value of the maximum height Rmax to 80 μm or less is not particularly limited. For example, (1) it is assumed that the paper substrate is composed of three or more layers stacked in the paper thickness direction. A method of including a magnetic material in a layer excluding an outer layer, and (2) a method of including a magnetic material between two layers, wherein the paper base material is composed of two or more layers laminated in the paper thickness direction. Furthermore, (3) a method of providing a coating layer on one side or both sides of a paper substrate is also suitable. The formation of the coating layer is particularly effective when the magnetic material is located in the vicinity of the surface of the paper substrate or when the paper substrate is a single layer.
Note that the method as described above is also effective in controlling the center line average roughness Ra to 3.0 μm or less.

The pulp fiber used as the main component of the paper base is not particularly limited, but examples thereof include hardwood and / or softwood kraft pulp fiber, sulfite pulp fiber, semi-chemical pulp fiber, chemiground pulp fiber, It is preferable to use ground pulp fiber, refiner ground pulp fiber, thermomechanical pulp fiber or the like. Moreover, the fiber which chemically modified the cellulose or hemicellulose in these fibers can also be used as needed.
Furthermore, cotton pulp fiber, hemp pulp fiber, kenaf pulp fiber, bagasse pulp fiber, viscose rayon fiber, regenerated cellulose fiber, copper ammonia rayon fiber, cellulose acetate fiber, polyvinyl chloride fiber, polyacrylonitrile fiber, polyvinyl alcohol fiber, Polyvinylidene chloride fibers, polyolefin fibers, polyurethane fibers, fluorocarbon fibers, glass fibers, carbon fibers, alumina fibers, metal fibers, silicon carbide fibers and the like can be used alone or in combination.

  In addition, if necessary, the amount of Taber wear and internal bonding can be obtained by using fibers obtained by impregnating or heat-sealing synthetic resin such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, and polyester into the pulp fibers. Strength can be improved.

  Furthermore, high-quality and medium-quality waste paper pulp can also be blended with the above pulp fibers. The amount of waste paper pulp is determined according to the use and purpose, but for example, when waste paper pulp is blended from the viewpoint of resource protection, it is 10 mass with respect to the total pulp fibers contained in the paper base material. % Or more, preferably 30% by mass or more. Furthermore, it is preferable to use pulp obtained from so-called certified forests, planted trees or thinned wood chips from the viewpoint of resource protection.

  In order to adjust opacity, whiteness, and surface properties, a filler may be added to the paper base material used in the recording medium of the present invention as necessary.

  The type of filler that can be used for the paper substrate is not particularly limited, and calcium carbonate-based fillers such as heavy calcium carbonate, light calcium carbonate, and chalk, kaolin, calcined clay, pyrophyllite, sericite, And silicates such as talc, titanium dioxide, calcium sulfate, barium sulfate, zinc oxide, zinc sulfide, zinc carbonate, aluminum silicate, calcium silicate, magnesium silicate, synthetic silica, aluminum hydroxide, alumina, white carbon, saponite, dolomite, Inorganic fillers such as calcium montmorillonite, sodium montmorillonite and bentonite, acrylic plastic pigments, polyethylene, chitosan particles, cellulose particles, polyamino acid particles, and organic fillers such as styrene can be used. From the viewpoint of image quality maintenance and whiteness improvement in the electrophotographic system, blending of calcium carbonate in neutral papermaking is preferable.

Furthermore, various chemicals such as a sizing agent can be internally or externally added to the paper substrate constituting the recording medium of the present invention.
Examples of sizing agents that can be added to the paper substrate include sizing agents such as rosin sizing agents, synthetic sizing agents, petroleum resin sizing agents, and neutral sizing agents. Further, a sizing agent such as a sulfate band or cationized starch may be used in combination with a fixing agent.

  Among the above sizing agents, in the electrophotographic image forming apparatus, from the viewpoint of storage stability of the recording medium after the image is formed, a neutral sizing agent, for example, an alkenyl succinic anhydride-based sizing agent, an alkyl ketene dimer, It is preferable to use alkenyl ketene dimer, neutral rosin, petroleum size, olefin resin, styrene-acrylic resin and the like. In addition, as a surface sizing agent, oxidized modified starch, enzyme-modified starch, modified cellulose such as polyvinyl alcohol and carboxymethyl cellulose, styrene acrylic latex, styrene maleic acid latex, acrylic latex and the like may be used alone or in combination. it can.

Furthermore, a paper strength enhancer can be internally or externally added to the paper substrate constituting the recording medium of the present invention.
The paper strength enhancers include starch, modified starch, vegetable gum, carboxymethyl cellulose, polyvinyl alcohol, modified polyvinyl alcohol, polyacrylamide, styrene-maleic anhydride copolymer, vinyl chloride-vinyl acetate copolymer, styrene-butadiene copolymer. Polymer, polyacrylate urea-formaldehyde resin, melamine-formaldehyde resin, dialdehyde starch, polyethyleneimine, epoxidized polyamide, polyamide-epichlorohydrin resin, methylolated polyamide, chitosan derivative, etc. Alternatively, they can be mixed and used.
In addition to these, various auxiliary agents blended in a normal paper medium such as a dye and a pH adjuster may be appropriately used.

  The recording medium of the present invention comprises a plurality of paper substrates (however, of a plurality of paper substrates prepared by mixing the main material constituting the paper substrate and other materials and making paper) At least one paper base material contains a magnetic material) may be bonded to each other, and a size press liquid application and a pigment coating layer described later may be formed as necessary. Also, after mixing the main material constituting the paper base material, the other materials constituting the paper base material, and the magnetic wire material, and making these or making a multi-layer paper, further described later if necessary It may be produced by applying a size press liquid and forming a pigment coating layer.

  The paper making method is not particularly limited. Any of a multi-layer paper making method, a conventionally known long net paper machine, a circular net paper machine, and a twin wire system can be used. Either acidic or neutral papermaking may be used.

  As the method of multi-layer papermaking, any of the following methods may be used: circular mesh multi-ply paper, long multi-cylinder, long net / circular net combination, multi-head box, short net / long net system, for example, by Saburo Ishiguro Any of the methods described in detail in “Latest papermaking technology—theory and practice” (Paper Chemistry Laboratory, 1984) may be used, or a multi-cylinder type with a plurality of round nets may be used.

Moreover, it is preferable to apply the following size press liquid to the surface of the paper base (when the recording medium is composed of a plurality of paper bases, the surface of the paper base of the outermost layer).
The binder used in the size press solution can be processed starch, such as raw starch such as corn starch, potato starch, tapioca starch, and enzyme-modified starch, phosphated starch, cationized starch, acetylated starch, etc. . In addition, water-soluble polymers such as polyethylene oxide, polyacrylamide, sodium polyacrylate, sodium alginate, hydroxymethyl cellulose, carboxymethyl cellulose, methyl cellulose, polyvinyl alcohol, guar gum, casein, curdlan, and derivatives thereof alone or Although it can be used by mixing, it is not limited to this. However, from the viewpoint of production cost, starch that is cheaper is often used.

  As a method of applying the size press liquid to the surface of the paper base material (the surface of the outermost paper base material when a recording medium is constituted by a plurality of paper base materials), in addition to the size press, shim size, Commonly used coating means such as a gate roll, a roll coater, a bar coater, an air knife coater, a rod blade coater, and a blade coater can be used.

  Further, the recording medium of the present invention can be used as a coated paper by forming a pigment coating layer by coating a coating liquid for a pigment coating layer mainly composed of an adhesive and a pigment on at least one side. .

In order to obtain a high gloss image, a resin layer can be provided on the pigment coating layer.
The resin used as the resin layer is not particularly limited as long as it is a known thermoplastic resin, for example, a resin having an ester bond; a polyurethane resin; a polyamide resin such as a urea resin; a polysulfone resin; a polyvinyl chloride resin, a polyvinylidene chloride Resin, vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-vinyl propionate copolymer resin; polyol resin such as polyvinyl butyral, cellulose resin such as ethyl cellulose resin and cellulose acetate resin; polycaprolactone resin, styrene-maleic anhydride Resin, polyacrylonitrile resin, polyether resin, epoxy resin, phenol resin; polyolefin resin such as polyethylene resin and polypropylene resin, copolymer resin of olefin such as ethylene and propylene and other vinyl monomers, acrylic It can be exemplified fat like.

  As the adhesive contained in the coating liquid for the pigment coating layer, one or both of water-soluble and water-dispersible polymer compounds are used. For example, cationic starch, amphoteric starch, oxidized starch, enzyme-modified starch , Starches such as thermochemically modified starch, esterified starch and etherified starch, cellulose derivatives such as carboxymethylcellulose and hydroxyethylcellulose, natural or semi-synthetic polymer compounds such as gelatin, casein, soy protein and natural rubber, polyvinyl Polydienes such as alcohol, isoprene, neoprene and polybutadiene, polyalkenes such as polybutene, polyisobutylene, polypropylene and polyethylene, vinyl halide, vinyl acetate, styrene, (meth) acrylic acid, (meth) acrylic acid ester, (meth) acrylamide , Methyl vinyl ether, etc. Synthetic polymer compounds such as nyl polymers and copolymers, synthetic rubber latex such as styrene-butadiene and methyl methacrylate-butadiene, polyurethane resin, polyester resin, polyamide resin, olefin-maleic anhydride resin and melamine resin Etc. can be used. Of these, one or more types are appropriately selected and used according to the quality target of the recording medium.

  Examples of the pigment contained in the coating liquid for the pigment coating layer include, for example, heavy calcium carbonate, light calcium carbonate, kaolin, calcined kaolin, structural kaolin, deramikaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, Mineral pigments such as zinc oxide, alumina, magnesium carbonate, magnesium oxide, silica, magnesium aluminosilicate, particulate calcium silicate, particulate magnesium carbonate, particulate light calcium carbonate, white carbon, bentonite, zeolite, sericite, smectite , Polystyrene resin, styrene-acrylic copolymer resin, urea resin, melamine resin, acrylic resin, vinylidene chloride resin, benzoguanamine resin and their fine hollow particles and through-hole type organic pigments. is there The two or more of them may be used.

  The blending ratio of the adhesive to the pigment in the pigment coating layer coating solution is preferably in the range of 5 to 50 parts by mass with respect to 100 parts by mass of the pigment. When the blending ratio of the adhesive with respect to 100 parts by mass of the pigment is less than 5 parts by mass, there is a problem that the coating film strength of the coating layer is low and paper dust is generated. On the other hand, if the amount exceeds 50 parts by mass, the adhesive may be excessive and the cost may be increased, and the practicality may be lowered.

  In the coating liquid for the pigment coating layer, various auxiliary agents such as surfactants, pH regulators, viscosity modifiers, softeners, gloss-imparting agents, dispersants, flow modifiers, antistatic agents, stability Necessary agent, antistatic agent, cross-linking agent, antioxidant, sizing agent, fluorescent brightener, colorant, UV absorber, antifoaming agent, water-resistant agent, plasticizer, lubricant, preservative, fragrance, etc. It is also possible to add appropriately according to.

The coating amount of the coating liquid for the pigment coating layer on the recording paper is appropriately selected according to the intended use of the recording medium of the present invention. irregularities is required amount that completely covers the one side per 2 to 20 g / m ² by dry weight, considering the cost is 2 to 8 g / m ² preferably.

  As a method of further applying the coating liquid for the pigment coating layer to the surface of the paper base material coated with the size press liquid, generally known coating apparatuses such as a blade coater, an air knife coater, a roll coater, and a reverse roll are used. A coater, bar coater, curtain coater, die coater, gravure coater, Champlex coater, brush coater, two-roll or metering blade type size press coater, bill blade coater, short dwell coater, gate roll coater and the like can be used as appropriate.

  The pigment coating layer is provided on a paper substrate, so that it is formed as one or both surface layers of a recording medium. The surface layer is a single layer or two or more intermediate layers as required, and has a multilayer structure. It is also possible. When coating on both sides of the paper or making it a multilayer structure, the amount of the coating solution for forming each coating layer must be the same, and the type and content of the above materials contained in the coating solution must be the same. Rather, it may be appropriately adjusted and blended according to a required quality level within a range satisfying the above specified range.

In addition, when a pigment coating layer is provided on one side of the recording medium, a synthetic resin layer, a coating layer made of an adhesive and a pigment, or an antistatic layer is provided on the other side to prevent curling and printing. It is also possible to give suitability, feed / discharge suitability, and the like.
Furthermore, it is of course possible to add various application suitability to the other surface of the recording medium by applying various processing such as adhesion, magnetism, flame retardancy, heat resistance, water resistance, oil resistance, and slip resistance. .

  The recording medium of the present invention is a super calender, gloss calender, soft calender and the like after the sizing agent, size press liquid, pigment coating layer coating liquid and the like are applied to the paper substrate surface as necessary. It is preferable to perform the smoothing process using a smoothing processing apparatus. Further, smoothing may be appropriately performed on-machine or off-machine, and the configuration of the pressure device, the number of pressure nips, heating, etc. may be adjusted as appropriate according to a normal smoothing processing device. That's fine.

The basis weight (JIS P-8124) of the recording medium of the present invention is not particularly defined, but is preferably 60 g / m ² or more. When the basis weight is less than 60 g / m ² , the size of the recording medium becomes small, so that the toner image transferred onto the recording medium is fixed on the surface when used in an electrophotographic image forming apparatus. In the process, there may be a case where an image defect is easily generated due to winding of the recording medium around the fixing device or peeling failure from the fixing device. Similarly, when the basis weight is less than 60 g / m ² , the magnetic material contained in the recording medium is used in the thickness direction of the recording medium when used in an electrophotographic or inkjet image forming apparatus. In the recording medium, it is likely to exist within a range of less than 5 μm from the surface of the recording medium.

  Further, in the recording medium of the present invention, the product moisture content immediately after being opened from a state sealed by moisture-proof packaging is within an appropriate range, specifically preferably 3 to 6.5% by mass, more preferably 4. It is preferable that the water content is adjusted by a paper machine or the like when making the paper base so that it falls within the range of about 5 to 5.5% by mass. In order to prevent moisture absorption and desorption when the produced recording medium is stored, the produced recording medium can be packaged using a moisture-proof wrapping paper such as polyethylene laminated paper or a material such as polypropylene every predetermined number of sheets. desirable.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to only these examples.

(Example 1)
In a pulp slurry in which 100 parts by mass of LBKP (hardwood bleached kraft pulp, freeness: 470 ml) and 7 parts by mass of a magnetic wire having a diameter of 25 μm and a length of 30 mm (composition: Fe base) are mixed, with respect to 100 parts by mass of pulp solids , Cationized starch (trade name: solar eclipse Neotac # 53, manufactured by Nippon Shokuhin Kako Co., Ltd.) 0.20 parts by mass, and alkenyl succinic anhydride (Fibrane 81, manufactured by Nippon NSC Co., Ltd.) 0.05 mass Parts were added.
Using a paper slurry (solid content concentration of 0.9% by mass) of these mixtures, a first paper base material layer is produced on an oriented paper machine (manufactured by Kumagaya Rikyu Kogyo Co., Ltd.) under the following papermaking conditions. did.
<Paper making conditions>
・ Drum rotation speed: 1000 rpm
Paper injection pressure: 1.0 kgf / cm ²
・ Paper ejection angle: 60 °
・ Number of strokes: 7

Next, the stock slurry (solid content concentration: 0.8% by mass) excluding the magnetic wire from the stock slurry is subjected to the following paper making conditions using an orientation paper machine (manufactured by Kumagai Riken Kogyo Co., Ltd.). Second and third paper base layers were prepared.
<Paper making conditions>
・ Drum rotation speed: 1000 rpm
Paper injection pressure: 1.0 kgf / cm ²
・ Paper ejection angle: 60 °
・ Number of strokes: 7 times

Then, the 2nd, 3rd paper base material layer was laminated | stacked on the front and back of the 1st paper base material layer. Subsequently, the sheet obtained by laminating the three paper base material layers was pressed for 1 minute at a pressure of 10 kgf / cm ² with a square sheet machine press (manufactured by Kumagai Riki Kogyo Co., Ltd.), and then the KRK rotary type The paper was dried at a heating temperature of 100 ° C. and a rotation speed of 100 cm / min with a drier (manufactured by Kumagaya Riki Kogyo Co., Ltd.) to obtain a paper having a basis weight of 105 g / m ² .

(Example 2)
95 parts by mass of LBKP (hardwood bleached kraft pulp, freeness: 470 ml), 5 parts by mass of NBKP (softwood bleached kraft pulp, freeness: 470 ml) and 6 parts by mass of a magnetic wire rod (composition: Fe base) having a diameter of 25 μm and a length of 30 mm In the obtained pulp slurry, 0.18 parts by mass of cationized starch (trade name: solar eclipse Neotac # 53, manufactured by Nippon Shokuhin Kako Co., Ltd.) and alkenyl succinic anhydride (Fibrin) with respect to 100 parts by mass of pulp solids. 81, manufactured by NSC Japan), 0.05 parts by mass. Using a paper slurry (solid content concentration of 0.9% by mass) of these mixtures, a first paper base material layer is produced on an oriented paper machine (manufactured by Kumagaya Rikyu Kogyo Co., Ltd.) under the following papermaking conditions. did.
<Paper making conditions>
・ Drum rotation speed: 1000 rpm
Paper injection pressure: 1.0 kgf / cm ²
・ Paper ejection angle: 60 °
・ Number of strokes: 7 times

Next, the stock slurry excluding the magnetic wire rod (solid content concentration: 0.8% by mass) from the above stock slurry is subjected to the following paper making conditions using an oriented paper machine (manufactured by Kumagai Riki Kogyo Co., Ltd.). Second and third paper base layers were prepared.
<Paper making conditions>
・ Drum rotation speed: 1000 rpm
Paper injection pressure: 1.0 kgf / cm ²
・ Paper ejection angle: 60 °
・ Number of strokes: 9 times

Then, the 2nd, 3rd paper base material layer was laminated | stacked on the front and back of the 1st paper base material layer. Subsequently, the sheet obtained by laminating the three paper base material layers was pressed for 1 minute at a pressure of 8 kgf / cm ² with a square sheet machine press (manufactured by Kumagai Riki Kogyo Co., Ltd.), and then the KRK rotary type The paper was dried with a drier (manufactured by Kumagaya Riki Kogyo Co., Ltd.) at a heating temperature of 100 ° C. and a rotation speed of 100 cm / min to obtain a paper having a basis weight of 109 g / m ² .

(Example 3)
Using the paper slurry (solid content concentration: 0.8% by mass) obtained by removing the magnetic wire material from the paper slurry used in Example 1, the following paper machine was made with an oriented paper machine (manufactured by Kumagaya Riki Kogyo Co., Ltd.). First and second paper base layers were produced under the conditions.
<Paper making conditions>
・ Drum rotation speed: 1000 rpm
Paper injection pressure: 1.0 kgf / cm ²
・ Paper ejection angle: 60 °
・ Number of strokes: 10

About 8 magnetic wires (diameter 25 μm, length 30 mm, composition: Fe base) are uniformly distributed on one side of the produced first paper base layer so that the magnetic wires do not overlap each other. A second paper base material layer was laminated thereon. Thus, the sheet | seat obtained by laminating | stacking the two-layer paper base material layer which contains a magnetic body wire at an interface is 12 kgf / cm < ² > with a square sheet machine press (made by Kumagai Riki Kogyo Co., Ltd.). The sheet was pressed for 1 minute, and then dried with a KRK rotary dryer (manufactured by Kumagai Riki Kogyo Co., Ltd.) at a heating temperature of 100 ° C. and a rotation speed of 100 cm / min to obtain a paper having a basis weight of 106 g / m ² .

Example 4
In a pulp slurry in which 100 parts by mass of LBKP (hardwood bleached kraft pulp, freeness: 470 ml) and 4 parts by mass of a magnetic wire (composition: Fe base) having a diameter of 16 μm and a length of 30 mm are mixed, with respect to 100 parts by mass of pulp solids Then, 0.10 parts by mass of cationized starch (trade name: MS4600, manufactured by Nippon Shokuhin Kagaku Kogyo Co., Ltd.) and 0.08 parts by mass of alkenyl succinic anhydride (Fibran 81, manufactured by NSC Japan) were added.
Sheets were produced under the following papermaking conditions by using an orientation paper machine (manufactured by Kumagaya Riki Kogyo Co., Ltd.) using the paper stock slurry (solid content concentration 0.9% by mass) of these mixtures.
<Paper making conditions>
・ Drum rotation speed: 1000 rpm
・ Paper injection pressure: 1.5 kgf / cm ²
・ Paper ejection angle: 60 °
・ Number of strokes: 15

Subsequently, the produced sheet was pressed for 1 minute with a square sheet machine press (manufactured by Kumagaya Riki Kogyo Co., Ltd.) at a pressure of 10 kgf / cm ² , and then a KRK rotary dryer (manufactured by Kumagai Riki Kogyo Co., Ltd.). And dried at a heating temperature of 100 ° C. and a rotation speed of 100 cm / min to obtain a paper substrate having a basis weight of 102 g / m ² .
Next, 100% by mass of a pigment component [light calcium carbonate (trade name: Tama Pearl T-123, manufactured by Okutama Kogyo Co., Ltd.) 50% by mass, kaolin (Ultra White 90, manufactured by Engelhard Co., Ltd.) 50% by mass ] 4% by mass of oxidized starch (Ace A, manufactured by Oji Cornstarch Co., Ltd.) as an adhesive (solid content ratio to pigment; hereinafter the same in this example) and synthetic adhesive (LX430 and 2507H, blending ratio) 25:75, 12% by mass of Nippon Zeon Co., Ltd.) and 0.2% by mass of a dispersant (Aron T-40, Toagosei Co., Ltd.) were blended to prepare a coating composition.
Thereafter, this coating composition was applied on both sides of the above-mentioned paper base material with a blade coater so that the dry weight was 8 g / m ² per side, and a paper having a basis weight of 118 g / m ² (coated paper) )

(Example 5)
Using the paper obtained in Example 1 as a paper base material, apply a coating composition similar to that used in Example 4 on both sides with a blade coater so that the dry weight is 8 g / m ² per side. And a paper (coated paper) having a basis weight of 121 g / m ² was obtained.

(Example 6)
In Example 3, paper making was performed in the same manner except that the number of strokes under the paper making conditions was set to 7, and a paper having a basis weight of 67 g / m ² was obtained.

(Example 7)
In Example 2, papermaking was performed in the same manner except that the number of strokes of the papermaking conditions for making the first, second, and third paper base material layers was 18, and a paper having a basis weight of 260 g / m ² was obtained. It was.

(Comparative Example 1)
In a pulp slurry in which 100 parts by mass of LBKP (hardwood bleached kraft pulp, freeness: 470 ml) and 8 parts by mass of a magnetic wire having a diameter of 25 μm and a length of 30 mm (composition: Fe base) are mixed, with respect to 100 parts by mass of pulp solids Then, 0.12 parts by mass of cationized starch (trade name: MS4600, manufactured by Nippon Shokuhin Kagaku Kogyo Co., Ltd.) and 0.08 parts by mass of alkenyl succinic anhydride (Fibran 81, manufactured by NSC Japan) were added.
Sheets were produced under the following papermaking conditions by using an orientation paper machine (manufactured by Kumagaya Riki Kogyo Co., Ltd.) using the paper stock slurry (solid content concentration 1.0% by mass) of these mixtures.
<Paper making conditions>
・ Drum rotation speed: 1000 rpm
Paper injection pressure: 1.0 kgf / cm ²
・ Paper ejection angle: 60 °
・ Number of strokes: 18 times

Subsequently, the produced sheet was pressed with a square sheet machine press (manufactured by Kumagaya Riki Kogyo Co., Ltd.) for 1 minute at a pressure of 5 kgf / cm ² , and then a KRK rotary dryer (manufactured by Kumagai Riki Kogyo Co., Ltd.). Were dried at a heating temperature of 100 ° C. and a rotation speed of 100 cm / min to obtain a paper having a basis weight of 104 g / m ² .

(Comparative Example 2)
In a pulp slurry in which 100 parts by mass of LBKP (hardwood bleached kraft pulp, freeness: 470 ml) and 8 parts by mass of a magnetic wire rod (composition: Fe base) having a diameter of 12 μm and a length of 30 mm are mixed, with respect to 100 parts by mass of pulp solids Then, 0.12 parts by mass of cationized starch (trade name: MS4600, manufactured by Nippon Shokuhin Kagaku Kogyo Co., Ltd.) and 0.06 parts by mass of alkenyl succinic anhydride (Fibran 81, manufactured by NSC Japan) were added.
Sheets were produced under the following papermaking conditions by using an orientation paper machine (manufactured by Kumagaya Riki Kogyo Co., Ltd.) using the paper stock slurry (solid content concentration 1.0% by mass) of these mixtures.
<Paper making conditions>
・ Drum rotation speed: 1000 rpm
Paper injection pressure: 1.0 kgf / cm ²
・ Paper ejection angle: 60 °
・ Number of strokes: 18 times

Subsequently, the produced sheet was pressed with a square sheet machine press (manufactured by Kumagaya Riki Kogyo Co., Ltd.) for 1 minute at a pressure of 3 kgf / cm ² , and then a KRK rotary dryer (manufactured by Kumagai Riki Kogyo Co., Ltd.). And dried at a heating temperature of 100 ° C. and a rotational speed of 100 cm / min to obtain a paper having a basis weight of 102 g / m ² .

(Comparative Example 3)
95 parts by mass of LBKP (hardwood bleached kraft pulp, freeness: 470 ml), 5 parts by mass of NBKP (softwood bleached kraft pulp, freeness: 470 ml) and 6 parts by mass of a magnetic wire rod (composition: Fe base) having a diameter of 25 μm and a length of 30 mm In the obtained pulp slurry, 0.18 parts by mass of cationized starch (trade name: solar eclipse Neotac # 53, manufactured by Nippon Shokuhin Kako Co., Ltd.) and alkenyl succinic anhydride (Fibrin) with respect to 100 parts by mass of pulp solids. 81, Nippon NSC Co., Ltd.)) 0.05 parts by mass was added.
Using a paper slurry (solid content concentration of 0.9% by mass) of these mixtures, a first paper base material layer is produced on an oriented paper machine (manufactured by Kumagaya Rikyu Kogyo Co., Ltd.) under the following papermaking conditions. did.
<Paper making conditions>
・ Drum rotation speed: 1000 rpm
Paper injection pressure: 1.0 kgf / cm ²
・ Paper ejection angle: 60 °
・ Number of strokes: 7 times

Next, using the stock slurry (solid content concentration: 0.8% by mass) from which the magnetic material wire is removed from the stock slurry, the following paper making conditions are applied by an orientation paper machine (manufactured by Kumagai Riki Kogyo Co., Ltd.). Second and third paper base layers were prepared.
<Paper making conditions>
・ Drum rotation speed: 1000 rpm
Paper injection pressure: 1.0 kgf / cm ²
・ Paper ejection angle: 60 °
・ Number of strokes: 7 times

The second and third paper base layers obtained by papermaking were laminated on the front and back surfaces of the first paper base layer. The sheet thus obtained was pressed for 1 minute with a square sheet machine press (manufactured by Kumagai Riki Kogyo Co., Ltd.) at a pressure of 3 kgf / cm ² , and then a KRK rotary dryer (Kumaya Riki Kogyo Co., Ltd.). Manufactured at a heating temperature of 100 ° C. and a rotation speed of 100 cm / min to obtain a paper having a basis weight of 101 g / m ² .

(Comparative Example 4)
A paper was prepared in the same manner as in Comparative Example 3 except that the number of strokes was changed to 4 in the papermaking conditions for making the first, second, and third paper base material layers of Comparative Example 3, and the basis weight was 66 g / m. ² sheets were obtained.

(Comparative Example 5)
A paper was produced in the same manner as in Comparative Example 3 except that the number of strokes was 18 under the papermaking conditions for making the first, second, and third paper base layers of Comparative Example 3, and the basis weight was 256 g / m. ² sheets were obtained.

-Evaluation-
For the evaluation, two types of image forming apparatuses (Fuji Xerox Co., Ltd.) were used after cutting the paper obtained in each Example / Comparative Example into A4 size paper, and adjusting the humidity at a temperature of 23 ° C. and a humidity of 50% for 12 hours or more. And DocuCenterColor f450 (hereinafter abbreviated as “DCCf450”) and DocuPrint 180EPS (hereinafter abbreviated as “DP180EPS”) in a plain paper mode and transfer missing when a halftone image (monochrome black 50%) is output on both sides. The image quality (granularity) was evaluated, and the results are shown in Table 1 below together with various characteristics of the paper, the number of layers of the paper base material, the presence or absence of a coating layer, and the like.

The evaluation of transfer loss and image quality shown in Table 1 was performed by visually observing the obtained image, and evaluated according to the following criteria.
<Evaluation of transfer omission>
G0: Transfer missing has not occurred.
G1: The image density is reduced in a part of the image, but there is no problem as a printed matter.
G2: The image density is generally low, but there is no problem as a printed matter.
G3: A part of the image is white and there is a problem as a printed matter.
G4: The image is entirely white and there is a problem as a printed matter.

<Evaluation of image quality (granularity)>
G0: No graininess problem.
G1: Although the graininess is slightly deteriorated, there is no problem as a printed matter.
G2: The granularity is poor and there is a problem as a printed matter.

It is a schematic diagram for demonstrating the measuring method of maximum height Rmax. It is a figure for demonstrating the large Barkhausen effect.

Explanation of symbols

10 Magnetic wire 20 Measurement area

Claims (2)

  A recording comprising a magnetic material, wherein at least one surface of the magnetic material blending part has a center line average roughness Ra of 3.0 μm or less and a maximum height Rmax of 80 μm or less. Medium.   The recording medium according to claim 1, wherein the magnetic material causes at least a large Barkhausen effect.