JP4828289B2 - Recording sheet - Google Patents

Description

  The present invention relates to a recording sheet that includes 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 the security of information is enhanced in order to prevent leakage of confidential information due to taking out 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 for anti-counterfeiting as described above, metal fibers such as magnetic materials are embedded or embedded in the paper. Convex part) occurs. Presence of such a convex part has not been a problem particularly in a special document in which predetermined information is printed in advance and is not assumed to be overwritten by a copying machine or the like.
However, printing paper used in the techniques disclosed in Patent Documents 3 and 4 and the like forms an image by electrophotography or the like when used. Therefore, if there are convex portions on the paper surface, transfer omission occurs. .
An object of the present invention is to solve the above problems. That is, an object of the present invention is to provide a recording paper that suppresses transfer omission due to a magnetic material contained in the paper when an image is formed by electrophotography.

The above-mentioned subject is achieved by the following present invention. That is, the present invention
<1>
A recording paper that includes one or more magnetic wires and pulp fibers, and does not have a pigment coating layer and a resin coating layer , wherein the content of the magnetic wires in the recording paper is the pulp fibers The recording paper is composed of a single layer having a density of 0.70 g / cm ³ or more and 0.90 g / cm ³ or less with respect to 100 parts by weight of at least one side of the recording paper. The maximum convex height is 100 μm or less.

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

  As described above, according to the present invention, it is possible to provide a recording sheet that suppresses transfer omission caused by the magnetic material contained in the sheet when an image is formed by electrophotography.

The recording paper of the present invention includes a magnetic material, and has a maximum convex height of 100 μm or less on at least one paper surface.
Therefore, when the recording paper of the present invention is used, transfer omission due to the magnetic material contained in the paper can be suppressed when an image is formed by electrophotography. The recording paper of the present invention is suitable for use as an electrophotographic transfer paper because transfer loss can be suppressed. However, the recording paper is not limited to this, and can be used in a known recording method, for example, ink jet recording. It can also be used as paper.

  As described above, the maximum convex height needs to be 100 μm or less, preferably 60 μm or less, more preferably 30 μm or less, and most preferably 0 μm, that is, flat. If the maximum convex height exceeds 100 μm, transfer omission (so-called white omission) occurs when an image is formed by an electrophotographic image forming apparatus. Further, from the same viewpoint, the maximum convex height is particularly preferably 100 μm or less on both sides of the paper. In this case, the occurrence of transfer omission can be prevented by using either the front or back side of the sheet. Further, when the maximum convex height exceeds 100 μm, when the paper is continuously fed, the inter-sheet friction coefficient at the convex portion is locally increased, which may cause problems such as misfeed. Also from the viewpoint of paper runnability, the maximum convex height needs to be 100 μm or less, preferably 60 μm or less, and more preferably 30 μm or less.

In the present invention, the maximum convex height was measured using a laser displacement meter (LT-8010 manufactured by Keyence Corporation). In the present invention, the measurement object for obtaining the maximum convex height is the height of the convex portion formed due to the magnetic material contained in the paper. Here, 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 sometimes referred to as “magnetic wire”) is preferably used. . Therefore, when measuring the height of the convex portion due to one magnetic wire, after confirming the position where the magnetic material is contained in the paper, it corresponds to the location (2 locations) inside 2 mm from both ends of the wire. A total of three locations on the paper surface corresponding to the paper surface and the central portion (one location) of the wire were measured.
FIG. 1 is a schematic diagram for explaining a method of measuring the convex height of the paper surface caused by the magnetic wire, and shows the arrangement of the magnetic wire contained in the recording paper in the paper surface direction. Here, in the figure, 10 represents a magnetic wire, and a dotted line represents a scanning line of a laser displacement meter. 1A shows a case where the magnetic wire is arranged linearly with respect to the paper surface direction, and FIG. 1B shows that the magnetic wire is meandered with respect to the paper surface direction. FIG. 1C shows a case where the magnetic wire is arranged so as to draw an arc with respect to the paper surface direction.
As shown in FIG. 1, regardless of the arrangement shape of the magnetic wire, the scanning of the laser displacement meter is always performed perpendicular to the length direction of the magnetic wire at the time of measurement, and one magnetic wire Is measured at three locations near both ends and near the center.

  The measurement length (scanning distance) is 10 mm (the middle position of the scanning distance is the center position in the center width direction of the magnetic wire), and the height is plotted every 10 μm, and within the measurement length range at this time From the difference between the maximum height and the minimum height, the convex height at each measurement location was obtained. The number of measurements per side of the paper was measured at three locations for each magnetic wire, and the maximum value among all the measured values was determined as the maximum convex height.

Next, the constituent material, manufacturing method, and various physical properties of the recording paper of the present invention will be described in more detail.
-Magnetic material-
The magnetic material contained in the recording paper 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 paper of the present invention is generally a permanent magnet, for example, a material mainly composed of rare earth neodymium (Nd) -iron (Fe) -boron (B), 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 recording paper in order to suppress the exposure of the magnetic wire on the surface of the recording paper. For example, the diameter of the recording paper having a thickness of about 90 μm is used. In some cases, 60 μm or less is preferable, and 50 μm or less is more preferable. Further, from the viewpoint of reducing the convex height, the maximum diameter is preferably 45 μm or less, and more preferably 40 μm or less.

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 paper 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 paper. It is preferable to satisfy the above-described range.

The recording paper 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 paper of the present invention is not particularly limited, but at least a paper base material containing pulp fibers as a main component may be included, and the paper base material may have a multilayer structure of two or more layers. . The magnetic material may be contained in any position in the recording paper, but is basically preferably contained in the paper base material.
However, since it is easy to control the maximum convex height on both sides of the paper to 100 μm or less, the paper base is composed of three or more layers stacked in the paper thickness direction, and the layers other than the outermost layer are magnetic. It is preferable that the material is included, and considering the production of the recording paper, it is particularly preferable that the paper base is composed of three layers, and the magnetic material is included in the central layer.
In order to control the maximum convex height of the paper surface to 100 μm or less, it is also preferable to provide a coating layer on one or both sides of the paper substrate. For the formation of the coating layer, when the size of the magnetic material is large, for example, when the diameter of the linear magnetic material is 50 μm or more, or when the paper thickness is small, specifically, the paper thickness is 90 μm or less. This is particularly effective in the case of.
When the paper substrate has two layers, only one layer contains the magnetic material. In this case, it is easy to control the convex height of the paper surface on the side provided with the other layer not containing the magnetic material to 100 μm or less.

As a method for reducing the maximum convex height, it is also preferable to reduce the density of the paper in addition to the method such as the multilayering of the layer configuration as described above. This is particularly effective when a magnetic material is included.
Here, the density of the sheet (i.e., the ratio of the basis weight for the paper thickness (basis weight / paper thickness)) is preferably at 0.88 g / cm ³ or less, more not less 0.85 g / cm ³ or less preferable. When the density of the paper exceeds 0.90 g / cm ³ , the maximum convex height may exceed 100 μm.
If the density of the paper is too small, the basis weight may be too low and the recording paper may become too small, or the paper thickness may need to be increased more than necessary. It is preferably 70 g / cm ³ or more.

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 fiber, polyolefin fiber, polyurethane fiber, polyvinyl chloride fiber, fluorocarbon fiber, glass fiber, carbon fiber, alumina fiber, metal fiber, silicon carbide fiber, etc., alone or in combination Can be used.

  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.
Further, from the viewpoint of resource protection, it is preferable to use pulp obtained from a so-called certified forest, afforestation tree or a thinned wood chip.

  In order to adjust the opacity, whiteness, and surface property, a filler may be added to the paper base material used for the recording paper 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 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 base constituting the recording paper 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 paper after the image is formed, a neutral sizing agent, for example, an alkenyl succinic anhydride 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 base constituting the recording paper 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. Polymers, polyacrylate urea-formaldehyde resin, melamine-formaldehyde resin, dialdehyde starch, polyethyleneimine, epoxidized polyamide, polyamide-epichlorohydrin resin, methylolated polyamide, chitosan derivatives, 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.

  In the recording paper of the present invention, the magnetic material wire is dispersed among a plurality of paper base materials prepared by mixing the main material constituting the paper base material and other materials and making the paper. Then, the paper base materials may be bonded to each other, and may be prepared by applying a size press solution and a pigment coating layer, which will be described later, 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 can be used: circular multi-ply paper, long multi-pipe, long / round net combination, multi-head box, short net / long net method, 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 round net multi-cylinder type in which a plurality of round nets are connected may be used.

  It is desirable that the magnetic material is not exposed on the surface of the recording paper. If the magnetic material is exposed on the surface of the recording paper, a leak will occur in the transfer process for transferring the toner image formed on the photosensitive member or intermediate transfer member onto the recording paper when an image is formed by electrophotography. May end up. For this reason, it is desirable to prevent the magnetic material from being exposed on the surface of the recording paper by arranging it in the inner layer of the paper base material in which the magnetic material is multilayered or providing a coating layer.

Moreover, it is preferable to apply the following size press liquid to the surface of the paper base (when the recording paper 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, phosphate esterified starch, cationized starch, and acetylated starch. . 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.

Further, since the recording paper of the present invention contains a magnetic material, if the surface of the magnetic material is not covered with an insulating layer made of resin, metal oxide, or the like, the electrical resistance around the magnetic material decreases. It becomes easy. Therefore, when an image is formed by electrophotography, a local transfer failure occurs in the vicinity of the portion where the magnetic material exists when transferring the toner image formed on the surface of the photosensitive member or the intermediate transfer member. In some cases, white spots in the image may occur.
From such a viewpoint, it is preferable to adjust the surface resistivity and volume resistivity of the recording paper to a predetermined range so that white spots are not easily generated. In order to perform such resistance adjustment, the recording paper of the present invention includes sodium chloride, potassium chloride, calcium chloride, sodium sulfate, zinc oxide, titanium dioxide, tin oxide, aluminum oxide, magnesium oxide, and the like as resistance adjusting agents. These inorganic materials, and organic materials such as alkyl phosphate ester salts, alkyl sulfate ester salts, sodium sulfonate salts, and quaternary ammonium salts can be used alone or in combination. Further, as a method of incorporating these resistance adjusting agents into the recording paper, these inorganic substances and organic materials may be contained in the size press liquid and applied to the surface of the paper substrate.

  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 paper 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 paper 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, methyl methacrylate-butadiene, polyurethane resin, polyester resin, polyamide resin, olefin-maleic anhydride resin, 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 paper.

  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, fine hollow particles thereof, and through-hole type organic pigments, etc. 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 it exceeds 50 parts by mass, the adhesive is excessive, the cost is increased, and the practicality is 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 pigment coating layer coating liquid on the recording paper is appropriately selected according to the purpose of use of the recording paper of the present invention. An amount that can completely cover the unevenness is required, and it is preferably ² to ²⁰ g / m ² per side in terms of dry mass, and ^{2 to} 8 g / m ² in view of cost.

  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 a surface layer on one or both sides of the recording paper. 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 recording paper or a multilayer structure, the amount of the coating solution for forming each coating layer is the same, and the type and content of the material contained in the coating solution are the same. It is not necessary, and it may be appropriately adjusted and blended according to a required quality level within a range satisfying the above specified range.

When a pigment coating layer is provided on one side of the recording paper, a synthetic resin layer, a coating layer composed 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 side of the recording paper by post-processing such as adhesion, magnetism, flame retardancy, heat resistance, water resistance, oil resistance, and slip resistance. .

  The recording paper of the present invention has a super calender, gloss calender, soft calender, etc. after the sizing agent, size press liquid, pigment coating layer coating liquid, etc. 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 paper 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 recording paper becomes smaller, so that the toner image transferred onto the recording paper is fixed onto the recording paper when used in an electrophotographic image forming apparatus. In the fixing process, there is a problem that it is easy to generate an image defect due to winding around the fixing device or defective peeling from the fixing device. Similarly, when the basis weight is less than 60 g / m ² , the magnetic material contained in the recording paper is exposed on the surface of the recording paper when used in an electrophotographic or inkjet image forming apparatus. In some cases, problems such as image visibility degradation due to exposure of the magnetic material to the surface of the recording paper may occur.

  Further, in the recording paper of the present invention, the product moisture content immediately after being opened from the state sealed by the 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 addition, in order to prevent moisture absorption and desorption when the produced recording paper is stored, the produced recording paper 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 92 parts by mass of LBKP (hardwood bleached kraft pulp), 8 parts by mass of NBKP (softwood bleached kraft pulp), and 5 parts by mass of a magnetic wire rod (composition: Fe base) having a diameter of 30 μm and a length of 30 mm are mixed. 0.15 parts by mass of cationized starch (trade name: MS4600, manufactured by Nippon Food Chemical Co., Ltd.) and alkenyl succinic anhydride (Fibran 81, manufactured by Oji National Co., Ltd.) with respect to 100 parts by mass of solid content 0.05 parts by weight were added.
A paper slurry (solid content concentration: 1.0% by mass) of these mixtures was paper-made using the orientation paper machine (manufactured by Kumagaya Riki Kogyo Co., Ltd.) under the following conditions.
<Paper making conditions>
・ Drum rotation speed: 1200m / min
・ Paper slurry injection pressure: 1.5 kgf / cm ²
・ Paper slurry ejection angle: 60 °
・ Number of strokes: 15
Next, the sheet obtained by papermaking was pressed with a square sheet machine press (manufactured by Kumagaya Rikyu Kogyo Co., Ltd.) for 1 minute at a pressure of 10 kgf / cm ² , and then a KRK rotary dryer (Kumaya Rikyu Kogyo). Manufactured at a heating temperature of 100 ° C. and a rotation speed of 100 cm / min to obtain a recording paper having a basis weight of 102 g / m ² .

(Example 2)
Using the stock slurry used in Example 1, paper was made using an orientation paper machine (manufactured by Kumagaya Rikkoku Kogyo Co., Ltd.) under the following conditions.
<Paper making conditions>
・ Drum rotation speed: 1500m / min
・ Paper slurry injection pressure: 2.0 kgf / cm ²
・ Paper slurry ejection angle: 75 °
・ Number of strokes: 12
Next, the sheet obtained by papermaking was pressed with a square sheet machine press (manufactured by Kumagaya Rikyu Kogyo Co., Ltd.) for 1 minute at a pressure of 10 kgf / cm ² , and then a KRK rotary dryer (Kumaya Rikyu Kogyo). Manufactured at a heating temperature of 100 ° C. and a rotational speed of 100 cm / min to obtain a recording paper having a basis weight of 105 g / m ² .

(Example 3)
Using the stock slurry used in Example 1, paper was made using an orientation paper machine (manufactured by Kumagaya Rikkoku Kogyo Co., Ltd.) under the following conditions.
<Paper making conditions>
・ Drum rotation speed: 1000m / min
・ Paper slurry injection pressure: 0.8 kgf / cm ²
・ Paper slurry ejection angle: 45 °
・ Number of strokes: 16
Next, the sheet obtained by papermaking was pressed with a square sheet machine press (manufactured by Kumagaya Rikyu Kogyo Co., Ltd.) for 1 minute at a pressure of 10 kgf / cm ² , and then a KRK rotary dryer (Kumaya Rikyu Kogyo). Manufactured at a heating temperature of 100 ° C. and a rotational speed of 100 cm / min to obtain a recording paper having a basis weight of 100 g / m ² .

Example 4
In a pulp slurry in which 90 parts by weight of LBKP (hardwood bleached kraft pulp), 10 parts by weight of NBKP (softwood bleached kraft pulp), and 5 parts by weight of a magnetic wire rod (composition: Co base) having a diameter of 15 μm and a length of 20 mm are mixed. 0.12 parts by mass of cationized starch (trade name: MS4600, manufactured by Nippon Food Chemical Co., Ltd.) and alkenyl succinic anhydride (Fibran 81, manufactured by Oji National Corporation) with respect to 100 parts by mass of solid content 0.05 parts by weight were added.
Paper slurry (solid content concentration: 0.8% by mass) of these mixtures was paper-made using an orientation paper machine (manufactured by Kumagaya Rikyu Kogyo Co., Ltd.) under the following conditions.
<Paper making conditions>
・ Drum rotation speed: 1200m / min
・ Paper slurry injection pressure: 1.5 kgf / cm ²
・ Paper slurry ejection angle: 60 °
・ Number of strokes: 12
Next, the sheet obtained by papermaking was pressed with a square sheet machine press (manufactured by Kumagaya Rikyu Kogyo Co., Ltd.) for 1 minute at a pressure of 10 kgf / cm ² , and then a KRK rotary dryer (Kumaya Rikyu Kogyo). Manufactured at a heating temperature of 100 ° C. and a rotational speed of 100 cm / min to obtain a recording paper having a basis weight of 63 g / m ² .

(Example 5)
In a pulp slurry in which 90 parts by mass of LBKP (hardwood bleached kraft pulp), 10 parts by mass of NBKP (coniferous bleached kraft pulp), and 5 parts by mass of a magnetic wire (composition: Co base) having a diameter of 52 μm and a length of 30 mm are mixed. 0.18 parts by mass of cationized starch (trade name: MS4600, manufactured by Nippon Shokuhin Kagaku Kogyo Co., Ltd.) and alkenyl succinic anhydride (Fibran 81, manufactured by Oji National Co., Ltd.) 0.08 part by mass was added.
A paper slurry (solid content concentration: 1.2% by mass) of these mixtures was paper-made using the orientation paper machine (manufactured by Kumagaya Riki Kogyo Co., Ltd.) under the following conditions.
<Paper making conditions>
・ Drum rotation speed: 1200m / min
・ Paper slurry injection pressure: 1.5 kgf / cm ²
・ Paper slurry ejection angle: 60 °
・ Number of strokes: 42
Next, the sheet obtained by papermaking was pressed with a square sheet machine press (manufactured by Kumagaya Rikyu Kogyo Co., Ltd.) for 1 minute at a pressure of 10 kgf / cm ² , and then a KRK rotary dryer (Kumaya Rikyu Kogyo). Manufactured at a heating temperature of 100 ° C. and a rotational speed of 100 cm / min to obtain a recording paper having a basis weight of 286 g / m ² .

( Reference Example 6)
100% by mass of pigment component [light calcium carbonate (trade name: Tama Pearl T-123, manufactured by Okutama Kogyo Co., Ltd.) 30% by mass, kaolin (Ultra White 90, manufactured by Engelhard Co., Ltd.) 70% by mass] 3% by mass of oxidized starch (Ace A, manufactured by Oji Cornstarch Co., Ltd.) as an adhesive (solid ratio to pigment; hereinafter the same in this example) and synthetic adhesive (LX430 and 2507H, blending ratio 20:80, Nippon Zeon) Co., Ltd.) 15% by mass and a dispersant (Aron T-40, manufactured by Toa Gosei Co., Ltd.) 0.3% by mass were blended to prepare a coating composition to be applied to the substrate.
Subsequently, the paper produced in Example 1 was used as a base material, and coating was performed on both sides of the base material with a blade coater so that the dry weight was 10 g / m ² per side, to obtain a recording paper.

( Reference Example 7)
A paper slurry (solid content concentration: 0.9% by mass) obtained by removing the magnetic wire rod from the paper slurry used in Example 1 was obtained by using an orientation paper machine (manufactured by Kumagai Riki Kogyo Co., Ltd.). 1 and 2 paper base layers were prepared (basis weight: first paper base layer 32 g / m ² , second paper base layer 29 g / m ² ). The papermaking conditions at this time are shown below.
<Paper making conditions>
・ Drum rotation speed: 1000m / min
・ Paper slurry injection pressure: 0.5 kgf / cm ²
・ Paper slurry ejection angle: 70 °
・ Stroke frequency: 6 times

Next, a third paper base material layer having a basis weight of 29 g / m ² was produced using the paper material slurry (solid content concentration: 1.0% by mass) used in Example 1 under the above papermaking conditions. Then, the sheet | seat obtained by laminating | stacking the 3rd paper base material layer on the surface of a 1st paper base material layer, and also laminating the 2nd paper base material layer on it is a square sheet machine press ( Pressed at a pressure of 10 kgf / cm ² for 1 minute by Kumagaya Riki Kogyo Co., Ltd., and then dried at a heating temperature of 100 ° C. and a rotation speed of 100 cm / min with a KRK rotary dryer (manufactured by Kumaya Riki Kogyo Co., Ltd.). As a result, a recording paper having a basis weight of 90 g / m ² was obtained.

( Reference Example 8)
The coating composition used in Reference Example 6 was applied to both sides of the recording paper of Reference Example 7 with a blade coater so that the dry weight was 8 g / m ² per side, and the basis weight was 106 g / m ² . A record sheet was obtained.

( Reference Example 9)
From the stock slurry used in Example 1, the stock slurry (solid content concentration: 0.9% by mass) excluding the magnetic wire was basis weight using an orientation paper machine (manufactured by Kumagaya Rikyu Kogyo Co., Ltd.). A first paper substrate layer of 58 g / m ² was produced. The papermaking conditions are shown below.
<Paper making conditions>
・ Drum rotation speed: 1000m / min
・ Paper slurry injection pressure: 1.5 kgf / cm ²
・ Paper slurry ejection angle: 70 °
-Number of strokes: 9 times Next, the second paper base material layer having a basis weight of 61 g / m ² under the above papermaking conditions using the paper material slurry (solid content concentration 1.0% by mass) used in Example 1. Was prepared and laminated on the surface of the first paper base material layer.
The sheet thus obtained was pressed with a square sheet machine press (manufactured by Kumagaya Rikyu Kogyo Co., Ltd.) for 1 minute at a pressure of 10 kgf / cm ² , and then with a KRK rotary dryer (manufactured by Kumagaya Rikyu Kogyo Co., Ltd.). A recording paper having a basis weight of 119 g / m ² was obtained by drying at a heating temperature of 100 ° C. and a rotational speed of 100 cm / min.
In this recording medium, the surface on the side provided with the first paper base material layer not including the magnetic wire is used as the surface, and the side on which the second paper base material layer including the magnetic wire is provided. The side was the back side.

(Comparative Example 1)
In a pulp slurry in which 95 parts by mass of LBKP (hardwood bleached kraft pulp), 5 parts by mass of NBKP (softwood bleached kraft pulp), and 5 parts by mass of a magnetic wire (composition: Fe base) having a diameter of 62 μm and a length of 35 mm are mixed. 0.15 parts by mass of cationized starch (trade name: MS4600, manufactured by Nippon Food Chemical Co., Ltd.) and alkenyl succinic anhydride (Fibran 81, manufactured by Oji National Co., Ltd.) with respect to 100 parts by mass of solid content 0.05 parts by weight were added.
A paper slurry (solid content concentration: 1.0% by mass) of these mixtures was paper-made using an orientation paper machine (manufactured by Kumagaya Riki Kogyo Co., Ltd.) under the following conditions.
<Paper making conditions>
・ Drum rotation speed: 800m / min
・ Paper slurry injection pressure: 0.8 kgf / cm ²
・ Paper slurry ejection angle: 30 °
・ Number of strokes: 20
Next, the sheet obtained by papermaking was pressed with a square sheet machine press (manufactured by Kumagaya Rikyu Kogyo Co., Ltd.) for 1 minute at a pressure of 10 kgf / cm ² , and then a KRK rotary dryer (Kumaya Rikyu Kogyo). Manufactured at a heating temperature of 100 ° C. and a rotational speed of 100 cm / min to obtain a recording paper having a basis weight of 127 g / m ² .

(Comparative Example 2)
In a pulp slurry in which 95 parts by mass of LBKP (hardwood bleached kraft pulp), 5 parts by mass of NBKP (coniferous bleached kraft pulp), and 5 parts by mass of a magnetic wire (copper fiber) having a diameter of 75 μm and a length of 25 mm are mixed. 0.15 parts by mass of cationized starch (trade name: MS4600, manufactured by Nippon Food Chemical Co., Ltd.) and 100% by mass of alkenyl succinic anhydride (Fibran 81, manufactured by Oji National Co., Ltd.) 06 parts by weight were added.
A paper slurry (solid content concentration: 1.0% by mass) of these mixtures was paper-made using the orientation paper machine (manufactured by Kumagaya Riki Kogyo Co., Ltd.) under the following conditions.
<Paper making conditions>
・ Drum rotation speed: 800m / min
・ Paper slurry injection pressure: 0.5 kgf / cm ²
・ Paper slurry ejection angle: 30 °
・ Number of strokes: 25
Next, the sheet obtained by papermaking was pressed with a square sheet machine press (manufactured by Kumagaya Rikyu Kogyo Co., Ltd.) for 1 minute at a pressure of 10 kgf / cm ² , and then a KRK rotary dryer (Kumaya Rikyu Kogyo). Manufactured at a heating temperature of 100 ° C. and a rotational speed of 100 cm / min to obtain a recording paper having a basis weight of 274 g / m ² .

-Evaluation-
The evaluation was performed using two types of image forming apparatuses (manufactured by Fuji Xerox, DocuCenterColor f450 (hereinafter referred to as “DCCf450”) by cutting the recording paper obtained in each Example / Reference Example / Comparative Example into A4 size paper. abbreviated) and DocuPrint 180EPS (hereinafter in abbreviated as "DP180EPS") by plain paper mode, to evaluate the half-tone image (50% single color black) the duplex transcription when spots (white spot). However, reference For the recording medium of Example 9, the white spot evaluation was performed only on the front side.
The results are shown in Table 1 below together with various characteristics of the paper such as the maximum convex height of the recording paper, the number of paper base layers, the presence or absence of a coating layer, the composition of the magnetic material, and the like. The print test was conducted continuously by setting 100 sheets of recording paper obtained in each of the examples / reference examples / comparative examples to the paper feed tray. Misfeeds sometimes occur in the recording medium.

The white spots shown in Table 1 were evaluated by visually observing the obtained image and evaluating according to the following criteria. G0, G1 and G2 are acceptable levels.
G0: No white spot occurs G1: Image density is low in a part of the image, but there is no problem as a printed matter G2: Image density on the paper surface of the part including the magnetic wire is generally low There is no problem as a printed matter. G3: A part of the image is missing 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.

It is a schematic diagram for demonstrating the measuring method of the convex height of the paper surface resulting from a magnetic body wire. It is a figure for demonstrating the large Barkhausen effect.

Explanation of symbols

10 Magnetic wire

Claims (2)

A recording paper that includes one or more magnetic wires and pulp fibers, and does not have a pigment coating layer and a resin coating layer , wherein the content of the magnetic wires in the recording paper is the pulp fibers The recording paper is composed of a single layer having a density of 0.70 g / cm ³ or more and 0.90 g / cm ³ or less with respect to 100 parts by weight of at least one side of the recording paper. A recording paper having a maximum convex height of 100 μm or less.   The recording paper according to claim 1, wherein the magnetic wire causes at least a large Barkhausen effect.