JP4696901B2 - Recording paper for electrophotography - Google Patents

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic recording paper suitable for forming an image by an electrophotographic method, and more specifically, an electrophotographic recording paper called a so-called plain paper that does not have a coating layer containing a pigment on the surface. About.

  Electrophotographic equipment, such as laser printers and copiers, now permeates most offices. Therefore, a recording paper that is mainly used is a recording paper that does not have a coating layer containing a pigment on a surface called a so-called plain paper.

  However, in the electrophotographic recording method, when the toner image transferred onto the paper is heat-fixed, it is heated from one side of the paper, and the paper curls due to dehumidification from the heating surface. In particular, when the humidity is high, the amount of curling is large because the paper contains a lot of moisture, and therefore, problems such as paper jamming at the paper discharge unit and poor storage capacity of the paper discharge tray tend to occur.

  Various studies have been made to improve the problem of curling after printing (curling after heat fixing). For example, a method of reducing the front / back difference in the fiber orientation of the paper and prescribing the moisture content at the time of opening (see, for example, Patent Document 1), and the residual curvature in the paper flow direction (MD direction) and cross direction (CD direction) There has been proposed a method for reducing the difference in distortion that is specified and remains on the front and back sides of the paper (for example, see Patent Document 2). With such a method of reducing the difference in front and back of the fiber orientation of the paper and a method of reducing the difference in strain remaining on the front and back, it is considered that the front and back difference in the expansion and contraction behavior of the paper is reduced.

  However, the image formation by the electrophotographic method is generally performed through a heat fixing process in which a sheet on which a toner image is formed is inserted between the heating unit and the pressure unit. In the process, the temperature differs between the heating part and the pressure part. On the other hand, in a paper containing a lot of moisture, the expansion and contraction behavior of the front and back surfaces due to moisture is different. Therefore, even if the front / back difference in the expansion / contraction behavior of the paper is reduced as described above, it seems difficult to reduce the curl after heat fixing. Even if the moisture content at the time of opening is lowered, if the paper is left under high humidity after opening, the paper absorbs moisture, and thus curling after heat fixing cannot be sufficiently suppressed.

  On the other hand, a method has been proposed in which the absolute value of the expansion / contraction ratio of the CD due to moisture change is reduced to suppress curling after heat fixing (see, for example, Patent Document 3).

JP-A-6-138688 Japanese Patent Laid-Open No. 3-243953 JP-A-5-341553

  Recent copiers and printers are becoming smaller and more complex, such as automatic double-sided copying, automatic bookbinding, and quick start-up. Progress is also being made. Therefore, in particular, when an image is formed in a high humidity environment where the moisture content of the paper is large, a small heat source has a heating source only on the fixing member side, and heat is applied from one side of the paper during fixing. In printers and the like, it has been considered that curling after heat fixing can be suppressed by reducing the absolute value of the CD expansion / contraction rate as in Patent Document 3. However, even when paper using the method described in Patent Document 3 is used, curling may occur after fixing.

  The present invention provides a recording sheet for electrophotography that can suppress curling that occurs after fixing when an image is formed by electrophotography.

The present invention provides an electrophotographic recording sheet mainly comprising pulp fibers, wherein the synthetic fibers comprising polyethylene resin, a filler, a basis weight of 45~90g / m 2 of ^paper, fiber orientation ratio of the paper Is 1.4 or less, the content of the filler in the paper is 2 to 3% by mass , and the relationship between the elongation at break and the thickness of the paper conditioned at 23 ° C. and 65% RH is the elongation at break (mm ) / Thickness (mm) ≦ 30, and the relationship between the maximum point load and the thickness until breakage is the maximum point load (N) / thickness (mm) ≧ 220.

  According to the present invention, in an electrophotographic recording paper on which an image is formed by electrophotography, the basis weight of the paper, the relationship between the breaking elongation and thickness in the oblique direction of the paper conditioned at 23 ° C. and 65% RH, and the breaking By adjusting the relationship between the maximum point load up to the time and the thickness to a predetermined value, curling that occurs after fixing can be suppressed.

  Embodiments of the present invention will be described below.

  The present inventors have diligently studied the cause of the occurrence of curling after fixing, such as the strength characteristics of the paper, the configuration of the image forming apparatus, and the image forming conditions.

First, the present inventors examined under what conditions the post-fixing curl is likely to occur when an image is formed by electrophotography using paper using the method described in Patent Document 3. . As a result, a small printer (an apparatus having a main body volume of 0.25 m ³ or less excluding paper feed and paper discharge trays), particularly an ultra-small printer (a main body volume excluding paper feed and paper discharge trays of 0.10 m). It was found out that curling tends to occur after fixing when using an apparatus of ³ or less.

  Further examination was made as to when the post-fixing curl is likely to occur by changing the image forming conditions and the type of the image forming apparatus. As a result, it has been found out that curling tends to occur after fixing when using a small printer which has been supplied to the market relatively recently. Therefore, the present inventors investigated characteristics common to small-sized printers that have begun to be supplied to the market relatively recently. As a result, in conventional small printers, the tension applied to the paper at the time of fixing is only in the paper feeding direction, whereas in recent small printers, in order to prevent paper wrinkles that occur during printing, It was found that tension was applied in the axial direction. That is, it was found that the paper is tensioned in both the MD and CD directions, and the paper that particularly contains water at a high temperature is plastically deformed by these tensions in the fixing device nip. This is considered to cause curling after fixing.

  Therefore, the present inventors considered that it is important to control the strength of the paper in the CD direction and the MD direction in order to suppress curling after fixing. Furthermore, as a result of studying the paper direction and tensile properties, paper that has not been focused on in the past has a smaller elongation at break in the “oblique direction” and has a higher maximum point load until the break in the “oblique direction”. Was found to be smaller. Japanese Patent Application Laid-Open No. 8-262811 proposes a method that defines the longitudinal and transverse geometric average value of the high-speed tensile elastic modulus. However, it is important that the paper does not have absolute strength and elongation. The curl reduction of humidity control paper is not enough.

That is, the electrophotographic recording paper according to the present embodiment (hereinafter sometimes referred to as “recording paper”) has pulp fiber as a main component,
The basis weight of the paper is 45 to 90 g / m ² ,
The relationship between the breaking elongation in the oblique direction and the thickness of the paper conditioned at 23 ° C. and 65% RH,
Elongation at break (mm) / Thickness (mm) ≦ 30
And the relationship between the maximum point load and the thickness until breakage is
Maximum point load (N) / thickness (mm) ≧ 220
It is. If the recording paper of this embodiment is used, curling that occurs after thermal fixing can be suppressed even if a recent small printer is used.

  The recording paper of this embodiment is preferably a so-called plain paper that does not have a coating layer substantially containing a pigment. Moreover, it is preferable that the recording paper of this embodiment contains a filler as a main component in addition to pulp fibers. Here, the total content of pulp fibers and filler is preferably 80% by mass or more.

The electrophotographic recording paper according to the present embodiment has a basis weight of 45 to 90 g / m ² , but preferably has a basis weight of 50 to 85 g / m ² . Basis weight it becomes difficult to reduce the post-fixing paper curl high moisture by increasing the small and the maximum point load and elongation at break is less than 45 g / m ^2, a small printer exceeds 90 g / m ² Since the heat capacity of the fixing device is small, the temperature difference between the heated roll side and the non-heated roll side of the sheet is increased, a difference in shrinkage due to moisture dehumidification is generated, and curling tends to increase.

  In addition, in order to suppress curling that occurs after heat fixing, the elongation at break and the maximum point load in the oblique direction of the recording paper in a state where the recording paper absorbs moisture as described above are important. Curling can be suppressed by reducing the elongation at the time of breaking in the oblique direction of the paper and increasing the maximum point load so that curling can be sufficiently suppressed.

In this embodiment, the relationship between the breaking elongation in the oblique direction and the thickness of the paper conditioned at 23 ° C. and 65% RH is as follows:
Elongation at break (mm) / Thickness (mm) ≦ 30
In Although,
Elongation at break (mm) / Thickness (mm) ≦ 25
It is preferable that When the elongation (mm) / thickness (mm) at the time of breaking in the oblique direction of the paper is larger than 30, curl generated after heat fixing cannot be suppressed particularly when a recent small printer is used.

In the present embodiment, the relationship between the maximum point load and the thickness until the break in the oblique direction of the paper conditioned at 23 ° C. and 65% RH is as follows:
Maximum point load (N) / thickness (mm) ≧ 220
In Although,
Maximum point load (N) / thickness (mm) ≧ 230
It is preferable that When the maximum point load (N) / thickness (mm) in the oblique direction of the sheet is less than 220, curling generated after heat fixing cannot be suppressed particularly when a recent small printer is used.

  Here, as shown in FIG. 1, the oblique direction of the paper indicates a direction of 45 degrees from the edge angle of the paper 10, and the tensile property evaluation sample is cut so as to be parallel to the 45 degree direction. .

  A method for measuring elongation at break and maximum point load will be described. A sample was cut out so that the paper was conditioned at 23 ° C. and 65% RH for 15 hours or more, preferably 15 hours to 20 hours, and parallel to the oblique 45 ° direction of the paper as described above, and measured by the method of JIS P8113. The sample width was 15 mm, the distance between the tensile tester grips was 150 mm, and the tensile speed was 10 mm / min.

  The thickness of the paper was measured by the method of JIS P8118 on a paper conditioned at 23 ° C. and 65% RH for 15 hours or more, preferably 15 hours to 20 hours.

  Methods for reducing the elongation at break in the oblique direction at 23 ° C. and 65% RH humidity of the electrophotographic recording paper include a method of reducing the fiber orientation ratio of the paper, a method of reducing fillers, and a method of blending synthetic fibers. It is preferable to combine a plurality of these methods. In addition, as a method of increasing the maximum point load in the oblique direction at the time of humidity control at 23 ° C. and 65% RH, a method of reducing the fiber orientation ratio of the paper, a method of reducing the filler, a method of blending synthetic fibers, and moisture conditioning moisture of the paper The method of making it low, the method of adding a wet paper strength enhancer, etc. are mentioned, It is preferable to combine two or more of these methods. By combining a plurality of these methods, it is possible to reduce the elongation at break in the oblique direction, which could not be achieved conventionally, and to increase the maximum point load in the oblique direction.

  Specific methods for reducing the fiber orientation ratio of the paper include a method of weakening the fiber orientation (the tendency of the pulp fibers to be aligned in the flow direction) by adjusting the wire speed and raw material jet (jet) speed or by wire shaking. It is done.

The fiber orientation ratio is a fiber orientation ratio determined by an ultrasonic propagation velocity method, and the ultrasonic propagation velocity in the MD direction of the recording paper (traveling direction of the paper machine) is defined as the CD direction of the recording paper (progress of the paper machine). The value divided by the ultrasonic propagation velocity in the direction perpendicular to the direction) is represented by the following formula (1).
Fiber orientation ratio (T / Y ratio) by ultrasonic wave propagation speed method of base paper = MD direction ultrasonic wave propagation speed / CD direction ultrasonic wave propagation speed (1)

  In the present embodiment, the fiber orientation ratio by the ultrasonic propagation velocity method is preferably 1.4 or less, and more preferably 1.2 or less. When the fiber orientation ratio exceeds 1.4, the fibers are oriented in the MD direction, so that the elongation at break in the oblique direction at 23 ° C. and 65% RH humidity is large, and the maximum point load in the oblique direction is small. Curling is likely to occur. In addition, the fiber orientation ratio by this ultrasonic propagation velocity method can be measured using SonicSheetTester (manufactured by Nomura Corporation).

  As a method of reducing the filler, the smaller the amount of filler added, the stronger the interfiber bond strength of the paper, so that the elongation at break in the oblique direction at 23 ° C. and 65% RH humidity can be reduced, and the recording paper is inclined. Since the maximum point load in the direction can be increased, it is preferable to add 2 to 10% by mass in the recording paper, and more preferably 2 to 5% by mass.

  By blending synthetic fiber, it is possible to suppress a decrease in strength when the moisture content is high, so the elongation at break in the oblique direction at 23 ° C. and 65% RH humidity control is reduced, and the maximum point load in the oblique direction Can be increased. Synthetic fibers that can be used include polyvinyl chloride fibers, polyacrylonitrile fibers, polyvinyl alcohol fibers, polyvinylidene chloride fibers, polyurethane fibers, polyvinyl chloride / polyvinyl alcohol copolymers, fluorocarbon fibers, aramid fibers, Polyethylene fiber, polypropylene fiber, polyester fiber and the like can be used alone or in combination, and among these, polyethylene fiber is preferred from the viewpoint of strength, color and the like. The blending amount on the paper is preferably in the range of 5% by mass to 30% by mass with respect to the mass of the recording paper. By blending synthetic fibers to reduce the hygroscopicity of the paper, the elongation at break in the oblique direction can be reduced and the maximum point load in the oblique direction can be increased.

  In order to increase the maximum point load in the oblique direction at the time of humidity adjustment at 23 ° C. and 65% RH, there is a method of reducing the moisture content of the recording paper. Since the paper tends to stretch when it absorbs moisture, it is preferable to reduce the moisture content. In order to reduce moisture conditioning moisture, the amount of synthetic fiber, the type of pulp, the beating degree is adjusted, or the hydroxyl group of cellulose is reacted to reduce the hydrophilicity of cellulose. Examples of the method include coating or internal addition. As the pulp, chemical pulp is preferable, and it is preferable not to proceed beating. The humidity control moisture referred to here is JIS P8127 paper and paperboard-moisture test method- by leaving the paper naked for 15 hours or more, preferably 15 hours to 24 hours, one by one in a 23 ° C. and 65% RH environment. It is obtained in accordance with the method using a dryer.

  By adding the wet paper strength enhancer, it is possible to suppress a decrease in strength in a state where the moisture content is high, and thus it is possible to increase the maximum point load in the oblique direction during humidity control at 23 ° C. and 65% RH. As the wet paper strength enhancer that can be used, polyamide / epichlorohydrin resin, polyamide resin, polyamide epoxy resin, etc. can be used singly or in combination. -Epichlorohydrin resin is preferred. The blending amount on the paper is preferably in the range of 1% by mass to 20% by mass as the active ingredient with respect to the mass of the recording paper.

  Next, constituent materials, physical properties, manufacturing methods, and the like of the recording paper according to the present embodiment will be described in more detail.

  As pulp fibers used for the recording paper according to the present embodiment, chemical pulp, specifically hardwood bleached kraft pulp, hardwood unbleached kraft pulp, softwood bleached kraft pulp, softwood unbleached kraft pulp, hardwood bleached sulfite pulp, hardwood Preferable examples include unbleached sulfite pulp, softwood bleached sulfite pulp, and softwood unbleached sulfite pulp, as well as pulp produced by chemically treating wood and fiber raw materials such as cotton, hemp, and leather.

  In addition, ground wood pulp that mechanically pulps wood and chips, chemimechanical pulp mechanically pulped after chemicals are soaked into wood and chips, and pulping with refiner after chips are softened slightly Thermomechanical pulp, especially chemithermomechanical pulp, which is characterized by high yield, can also be used. These may be used only with virgin pulp, or waste paper pulp may be added as necessary. However, chemical pulp is preferred from the viewpoint of hygroscopicity.

  In particular, the virgin pulp is bleached mainly using ozone / hydrogen peroxide or the like without using chlorine gas and using chlorine dioxide (Elementary Chlorine Free: ECF) or without using any chlorine compound. It is preferably one that has been bleached by the method (Total Chlorine Free: TCF).

  In addition, as raw materials of the waste paper pulp, unprinted waste paper such as cuts, damaged paper, widened white, special white, medium white, white loss, etc. generated in bookbinding, printing factories, cutting offices, etc .; printing and copying High-quality printed paper such as high-quality paper, high-quality coated paper, etc .; water-based ink, oil-based ink, old paper written with a pencil, etc .; printed high-quality paper, high-quality coated paper, medium-quality paper, medium-quality coated paper, etc. Newspaper waste paper including flyers; waste paper such as medium-quality paper, medium-quality coated paper, and reprint paper;

  The waste paper pulp used in the base paper used for the recording paper of this embodiment is preferably obtained by treating the waste paper pulp raw material with at least one of ozone bleaching treatment and hydrogen peroxide bleaching treatment.

  The ozone bleaching treatment has an action of decomposing fluorescent dyes or the like normally contained in high-quality paper, and the hydrogen peroxide bleaching treatment has an action of preventing yellowing due to alkali used during deinking treatment.

  By combining two treatments, ozone bleaching treatment or hydrogen peroxide bleaching treatment, the waste paper pulp not only facilitates deinking of the waste paper, but also improves the whiteness of the pulp. In addition, since there is also an action of decomposing and removing residual chlorine compounds in the pulp, a great effect can be obtained in reducing the content of organic halogen compounds in waste paper using chlorine bleached pulp. Moreover, when using a medium-sized waste paper, it is preferable to use a thing with little lignin amount in a bleaching process from a hygroscopic viewpoint.

  As a kind of pulp, it is preferable to use a chemical pulp from a hygroscopic viewpoint, and it is preferable to use a dry pulp.

  Moreover, you may mix | blend the said synthetic fiber from a viewpoint of moisture absorption suppression.

  In addition to the pulp fiber, it is preferable to add a filler to the base paper used in the present embodiment in order to adjust the opacity, whiteness, and surface properties. In order to reduce the amount of halogen in the recording paper, it is preferable to use a filler that does not contain halogen.

  As the filler, heavy calcium carbonate, light calcium carbonate, chalk, kaolin, calcined clay, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, aluminum silicate, calcium silicate, magnesium silicate, Synthetic silica, aluminum hydroxide, alumina, sericite, white carbon, saponite, calcium montmorillonite, sodium montmorillonite, bentonite and other inorganic pigments, acrylic plastic pigments, polyethylene, chitosan particles, cellulose particles, polyamino acid particles, urea Examples thereof include organic pigments such as resins.

Although the kind of filler to add is not specifically limited, A filler with a small specific surface area is preferable. The specific surface area is preferably 3 m ² / g or less, more preferably 2 m ² / g or less.

  As the amount of filler to be added, it is preferable that the amount is small as described above because the maximum point load of the recording paper can be increased. Therefore, the addition of 2 to 10% by mass in the recording paper is preferable, and more preferably 2 to 5% by mass. .

  In addition, when used paper pulp is blended with the base paper, it is necessary to estimate the ash contained in the used paper pulp raw material in advance and adjust the addition amount.

  In the present embodiment, as described above, in order to increase the maximum point load in the oblique direction at the time of humidity control at 23 ° C. and 65% RH, there is a method of reducing the moisture content of the recording paper. A material that suppresses moisture absorption (a moisture absorption inhibitor) can be contained. As a moisture absorption inhibitor, a material that is less hygroscopic than cellulose, a material that is less hygroscopic than oxidized starch used during normal size pressing, or the like can be used. In addition, the moisture absorption inhibitor said here means a thing whose humidity-control water | moisture content is 10% or less when humidity-controlling material itself for 15 hours in 23 degreeC and 65% RH environment.

  As the moisture absorption inhibitor, water-soluble ones are preferable from the viewpoint of production suitability and cost, and sugar, sugar alcohol, polyvinyl alcohol (PVA) and the like are preferable. Examples of sugars and sugar alcohols include maltitol, lactitol, erystole, twin-tose (registered trademark, manufactured by FANCL), palatinose, maltosyl trehalose, trehalose, and the like. A stall is preferred.

  When the moisture absorption inhibitor is applied to the surface of the base paper, it can be applied using a treatment liquid containing the moisture absorption inhibitor and a water-soluble resin. Examples of the water-soluble resin include carboxymethyl cellulose, hydroxypropyl cellulose, hydroxyethyl cellulose, polyvinyl alcohol (PVA), modified cationized polyvinyl alcohol, cationized starch, oxidized starch, anionized starch, nonionic starch, enzyme-modified starch, ether Combined use with modified starch and the like can be mentioned.

  In addition to the size press process of the pound method, the treatment liquid is a commonly used coating means such as a metering size press coater, a gate roll coater, a roll coater, a bar coater, an air knife coater, a rod blade coater, and a blade coater. Can be applied to the surface of the base paper.

The content of moisture inhibitor in the recording sheet is preferably in the range of 0.1-2 g / ^{m 2,} and more preferably in the range of 0.2 to 1.5 g / ^{m 2.} When the content of the moisture absorption inhibitor used in the present embodiment exceeds ² g / m ² , the texture as plain paper may be impaired. Moreover, since the moisture absorption inhibitory effect is small as it is less than 0.1 g / m < ² >, the effect of reducing the curl at the time of humidity control may become small.

The recording paper according to the present embodiment has a surface electrical resistivity of 1.0 × 10 ⁹ to 23 ° C. and 50% RH in order to provide sufficient toner transferability when an image is formed by electrophotography. is preferably 1.0 × ^{10 12} Ω / □ range, more preferably in the range of ^{10 12 Ω / □ 5.0 × 10} 9 ~1.0 ×, 1.0 × 10 10 ~1 More preferably, it is in the range of 0.0 × 10 ¹¹ Ω / □.

From the same point of view, the volume electrical resistivity of the recording paper of this embodiment is preferably in the range of 1.0 × 10 ^{10 to} 1.0 × 10 ¹² Ω · cm, and 1.3 × 10 ¹⁰ to The range of 1.6 × 10 ¹¹ Ω · cm is more preferable, and the range of 1.3 × 10 ^{10 to} 4.3 × 10 ¹⁰ Ω · cm is more preferable.

  In addition, the measurement of said electrical resistivity is measured by the method based on JISK6911 in the environment of 23 degreeC and 50% RH. As a measuring device, a digital ultrahigh resistance meter R8340 manufactured by Advantest and a resistance chamber R12704 were used, and the applied voltage was measured at 100V. The sample was measured after standing in an environment of 23 ° C. and 50% RH for 15 hours or longer, preferably 15 to 24 hours.

  The sizing degree of the recording paper of the present embodiment can be adjusted to a required value only by the amount and type of the binder. However, if the adjustment of the sizing degree is not sufficient by itself, a surface sizing agent may be further used. As such a surface sizing agent, rosin sizing agents, synthetic sizing agents, petroleum resin sizing agents, neutral sizing agents, starch, polyvinyl alcohol and the like can be used.

  Moreover, an internal additive sizing agent may be blended in the preparation stage of the stock in the paper making process, and the sizing degree may be adjusted in advance. In order to reduce the amount of halogen in the recording paper, it is preferable to use an internal sizing agent or a surface sizing agent that does not contain halogen. Specifically, rosin sizing agents, synthetic sizing agents, petroleum resin sizing agents, neutral sizing agents, and the like can be used.

  Further, a sizing agent and a fiber fixing agent can be used in combination. In this case, aluminum sulfate, cationized starch or the like can be used as a fixing agent. Further, from the viewpoint of improving the storage stability of the recording paper, it is preferable to use a neutral sizing agent. The degree of sizing can be adjusted by the amount of sizing agent added.

  Further, from the viewpoint of improving toner transferability and improving graininess, the smoothness of the recording paper is preferably 20 to 100 seconds, and more preferably 70 to 100 seconds. If the smoothness is less than 20 seconds, the graininess may deteriorate. In addition, if the smoothness exceeds 100 seconds, high-pressure nip processing is performed during production in order to obtain high smoothness, and as a result, the opacity of the paper may decrease or the curl may increase. This is not preferable. The smoothness is measured according to JIS P 8119: 1998.

  Hereinafter, although an example and a comparative example are given and the present invention is explained more concretely in detail, the present invention is not limited to the following examples.

<Example 1>
400 ml c. s. f. The following internal chemicals and fillers are dried per 100 parts by mass of pulp in which 90 parts by mass of hardwood bleached kraft pulp (LBKP) and 10 parts by mass of polyethylene fibers (Dyneema SK60: manufactured by Toyobo) are blended. Added by mass to make paper stock.
Alkenyl succinic anhydride (Fibran 81 manufactured by Nippon SC): 0.1 parts by weight Cationized starch (Cato-302 manufactured by Nippon NC): 1.0 parts by weight Heavy calcium carbonate (Softon 1200, manufactured by Bihoku Flour Industries) : 3 parts by mass Using this stock, the jet wire ratio was changed with a long paper machine to make a fiber orientation ratio of 1.4, and a substrate was obtained through a size press and a machine calendar.

Next, a solution having the following composition was prepared as a surface size press solution.
Water: 83 parts by mass Surface sizing agent (Arakawa Chemical Industries, Polymeron 1355, solid content 25%): 6 parts by mass Oxidized starch (Ace A manufactured by Oji Cornstarch Co., Ltd.): 10 parts by mass Conductive agent (sodium sulfate): 1 part by mass Application An equal amount was applied to both sides of the base paper, dried and calendered so that the total amount was 1.8 g / m ² on both sides, and a recording paper having a basis weight of 66 g / m ² was obtained.

  A sample of a recording paper that has been conditioned at 23 ° C. and 65% RH for 15 hours is cut out so that it is parallel to the diagonal direction of the paper, and the maximum breaking point and the maximum point load in the diagonal direction are measured by the method of JIS P8113. did. The sample width was 15 mm, the distance between the tensile tester grips was 150 mm, and the tensile speed was 10 mm / min. The thickness of the paper was measured by the method of JIS P8118 using a micrometer. Accordingly, the elongation (mm) / thickness (mm) at the time of breaking in the oblique direction in the humidity control at 23 ° C. and 65% RH of the recording paper of Example 1 is 30, and the maximum load (N) / thickness until breaking ( mm) was 222. The results are shown in Table 1.

<Example 2>
400 ml c. s. f. The following internal chemicals and fillers are dried per 100 parts by mass of pulp in which 90 parts by mass of hardwood bleached kraft pulp (LBKP) and 10 parts by mass of polyethylene fibers (Dyneema SK60: manufactured by Toyobo) are blended. Added by mass to make paper stock.
Alkenyl succinic anhydride (Fibran 81 made by Nippon SC): 0.1 parts by weight Cationized starch (Cato-302 made by Nippon NC): 1.0 parts by weight Polyamide / epichlorohydrin resin (wet paper strength enhancer WS4020) Starlight PMC): 1.0 part by weight Heavy calcium carbonate (Softon 1200, manufactured by Bihoku Powder Chemical Co., Ltd.): 3 parts by weight Using this stock, the jet wire ratio was changed with a long net paper machine, and fiber orientation Paper was made so that the ratio was 1.2, and a substrate was obtained through a size press and a machine calendar.

Next, a solution having the following composition was prepared as a surface size press solution.
Water: 83 parts by mass Surface sizing agent (Arakawa Chemical Industries, Polymeron 1355, solid content 25%): 6 parts by mass Oxidized starch (Ace A manufactured by Oji Cornstarch Co., Ltd.): 10 parts by mass Conductive agent (sodium sulfate): 1 part by mass Application An equal amount was applied to both sides of the base paper, dried and calendered so that the total amount was 1.8 g / m ² on both sides, and a recording paper having a basis weight of 66 g / m ² was obtained. In the same manner as in Example 1, the elongation at break in the oblique direction, the maximum point load in the oblique direction until the break, and the thickness of the sheet were measured, and the oblique direction at 23 ° C. and 65% RH in the recording sheet of Example 2 was measured. The elongation (mm) / thickness (mm) at break was 21, and the maximum load (N) / thickness (mm) until break was 250. The results are shown in Table 1.

<Example 3>
A recording paper of Example 3 was prepared in the same manner as in Example 2 except that the blending amount of the synthetic fiber, polyethylene fiber (Dyneema SK60: manufactured by Toyobo Co., Ltd.) was 5 parts by mass. The oblique elongation at break, the maximum point load in the oblique direction until the break, and the thickness of the paper were measured in the same manner as in Example 1, and the oblique direction of the recording paper of Example 3 at 23 ° C. and 65% RH humidity control was measured. The elongation (mm) / thickness (mm) at break was 20, and the maximum load (N) / thickness (mm) until break was 220. The results are shown in Table 1.

< Reference example >
400 ml c. s. f. The following internal additives and fillers were added in dry mass to 100 parts by mass of pulp made of hardwood bleached kraft pulp (LBKP) to obtain a paper stock.
Alkenyl succinic anhydride (Fibran 81 made by Nippon SC): 0.1 parts by weight Cationized starch (Cato-302 made by Nippon NC): 1.0 parts by weight Polyamide / epichlorohydrin resin (wet paper strength enhancer WS4020) Starlight PMC): 1.0 part by weight Heavy calcium carbonate (Softon 1200, manufactured by Bihoku Powder Chemical Co., Ltd.): 3 parts by weight Using this stock, the jet wire ratio was changed with a long net paper machine, and fiber orientation Paper was made so that the ratio was 1.2, and a substrate was obtained through a size press and a machine calendar.

Next, a solution having the following composition was prepared as a surface size press solution.
Water: 83 parts by mass Surface sizing agent (Arakawa Chemical Industries, Polymeron 1355, solid content 25%): 6 parts by mass Oxidized starch (Ace A, manufactured by Oji Cornstarch Co., Ltd.): 10 parts by mass Twin-tose (hygroscopic inhibitor, manufactured by FANCL): 10 parts by mass Conductive agent (sodium sulfate): 1 part by mass Applying equal amounts on both sides of the base paper, drying and calendaring so that the total coating amount is 2.5 g / m ² , basis weight 68 g / m ² Obtained recording paper. In the same manner as in Example 1, the breaking elongation in the oblique direction, the maximum point load in the oblique direction until breaking, and the thickness of the paper were measured, and the breaking in the oblique direction at 23 ° C. and 65% RH humidity control of the recording paper of the reference example. The elongation (mm) / thickness (mm) at time was 22, and the maximum load (N) / thickness (mm) until breakage was 266. The results are shown in Table 1.

<Example 4 >
A recording paper of Example 4 was prepared in the same manner as in Example 1 except that the basis weight was 45 g / m ² . In the same manner as in Example 1, the oblique elongation at break, the maximum point load in the oblique direction until the break, and the thickness of the paper were measured, and the oblique direction at 23 ° C. and 65% RH humidity control of the recording paper of Example 4 was measured. The elongation (mm) / thickness (mm) at break was 28, and the maximum load (N) / thickness (mm) until break was 221. The results are shown in Table 1.

<Example 5 >
A recording paper of Example 5 was prepared in the same manner as in Example 1 except that the basis weight was 90 g / m ² . The oblique elongation at break, the maximum point load in the oblique direction until the break, and the thickness of the paper were measured in the same manner as in Example 1, and the oblique direction of the recording paper of Example 5 at 23 ° C. and 65% RH humidity control was measured. The elongation (mm) / thickness (mm) at break was 29, and the maximum load (N) / thickness (mm) until break was 255. The results are shown in Table 1.

<Example 6 >
400 ml c. s. f. The following internal chemicals and fillers are dried per 100 parts by mass of pulp in which 90 parts by mass of hardwood bleached kraft pulp (LBKP) and 10 parts by mass of polyethylene fibers (Dyneema SK60: manufactured by Toyobo) are blended. Added by mass to make paper stock.
Alkenyl succinic anhydride (Fibran 81 manufactured by Nippon SC): 0.1 parts by weight Cationized starch (Cato-302 manufactured by Nippon NC): 1.0 parts by weight Heavy calcium carbonate (Softon 1200, manufactured by Bihoku Flour Industries) : 3 parts by mass Using this stock, the jet wire ratio was changed with a long net paper machine to make a fiber orientation ratio of 1.2, and a substrate was obtained through a size press and a machine calendar.

Next, a solution having the following composition was prepared as a surface size press solution.
Water: 83 parts by mass Surface sizing agent (Arakawa Chemical Industries, Polymeron 1355, solid content 25%): 6 parts by mass Oxidized starch (Ace A, manufactured by Oji Cornstarch Co., Ltd.): 10 parts by mass Twin-tose (hygroscopic inhibitor, manufactured by FANCL): 10 parts by weight Conductive agent (sodium sulfate): 1 part by weight Applying equal amounts on both sides of the base paper, drying and calendering so that the coating amount is 2.5 g / m ^{2 in} total on both sides, basis weight 70 g / m ² Obtained recording paper. The oblique elongation at break, the maximum point load in the oblique direction until the break, and the thickness of the paper were measured in the same manner as in Example 1, and the oblique direction at 23 ° C. and 65% RH humidity control of the recording paper of Example 6 was measured. The elongation (mm) / thickness (mm) at break was 18, and the maximum load (N) / thickness (mm) until break was 255. The results are shown in Table 1.

<Example 7 >
400 ml c. s. f. The following internal chemicals and fillers are dried per 100 parts by mass of pulp in which 90 parts by mass of hardwood bleached kraft pulp (LBKP) and 10 parts by mass of polyethylene fibers (Dyneema SK60: manufactured by Toyobo) are blended. Added by mass to make paper stock.
Alkenyl succinic anhydride (Fibran 81 made by Nippon SC): 0.1 parts by weight Cationized starch (Cato-302 made by Nippon NC): 1.0 parts by weight Polyamide / epichlorohydrin resin (wet paper strength enhancer WS4020) Starlight PMC): 1.0 part by weight Heavy calcium carbonate (Softon 1200, manufactured by Bihoku Powder Chemical Co., Ltd.): 3 parts by weight Using this stock, the jet wire ratio was changed with a long net paper machine, and fiber orientation Paper was made so that the ratio was 1.2, and a substrate was obtained through a size press and a machine calendar.

Next, a solution having the following composition was prepared as a surface size press solution.
Water: 83 parts by mass Surface sizing agent (Arakawa Chemical Industries, Polymeron 1355, solid content 25%): 6 parts by mass Oxidized starch (Ace A, manufactured by Oji Cornstarch Co., Ltd.): 10 parts by mass Twin-tose (hygroscopic inhibitor, manufactured by FANCL): 10 parts by weight Conductive agent (sodium sulfate): 1 part by weight Applying equal amounts on both sides of the base paper, drying and calendering so that the coating amount is 2.5 g / m ^{2 in} total on both sides, basis weight 70 g / m ² Obtained recording paper. In the same manner as in Example 1, the oblique elongation at break, the maximum point load in the oblique direction until the break, and the thickness of the paper were measured, and the oblique direction at 23 ° C. and 65% RH humidity control of the recording paper of Example 7 was measured. The elongation (mm) / thickness (mm) at break was 17, and the maximum load (N) / thickness (mm) until break was 276. The results are shown in Table 1.

<Comparative Example 1>
A recording paper of Comparative Example 1 was prepared in the same manner as Example 1 except that the fiber orientation ratio was changed to 1.5 by changing the jet wire ratio. In the same manner as in Example 1, the oblique elongation at break, the maximum point load in the oblique direction until the break, and the thickness of the paper were measured, and the oblique direction of the recording paper of Comparative Example 1 at 23 ° C. and 65% RH humidity control was measured. The elongation (mm) / thickness (mm) at break was 33, and the maximum load (N) / thickness (mm) until break was 220. The results are shown in Table 2.

<Comparative example 2>
400 ml c. Of beating as the pulp material of the base material. s. f. The recording paper of Comparative Example 2 was prepared in the same manner as in Example 1 except that hardwood bleached kraft pulp (LBKP) was 100% and the filler content was 5 parts by mass. The oblique elongation at break, the maximum point load in the oblique direction until the break, and the thickness of the paper were measured in the same manner as in Example 1. The recording paper of Comparative Example 2 was observed in the oblique direction at 23 ° C. and 65% RH humidity control. The elongation (mm) / thickness (mm) at break was 30, and the maximum load (N) / thickness (mm) until break was 172. The results are shown in Table 2.

<Comparative Example 3>
400 ml c. Of beating as the pulp material of the base material. s. f. The recording paper of Comparative Example 3 was prepared in the same manner as in Example 1 except that the hardwood bleached kraft pulp (LBKP) was 100%, the fiber orientation ratio was 1.2, and the filler content was 5 parts by mass. The oblique elongation at break, the maximum point load in the oblique direction until the break, and the thickness of the paper were measured in the same manner as in Example 1, and the oblique direction of the recording paper of Comparative Example 3 at 23 ° C. and 65% RH humidity control was measured. The elongation (mm) / thickness (mm) at break was 24, and the maximum load (N) / thickness (mm) until break was 196. The results are shown in Table 2.

<Comparative example 4>
400 ml c. s. f. The following internal additives and fillers were added in dry mass to 100 parts by mass of pulp made of hardwood bleached kraft pulp (LBKP) to obtain a paper stock.
Alkenyl succinic anhydride (Fibran 81 manufactured by Nippon SC): 0.1 parts by weight Cationized starch (Cato-302 manufactured by Nippon NC): 1.0 parts by weight Heavy calcium carbonate (Softon 1200, manufactured by Bihoku Flour Industries) : 10 parts by weight Using this stock, the jet wire ratio was changed with a long paper machine to make a fiber orientation ratio of 1.6, and a substrate was obtained through a size press and a machine calendar.

Next, a solution having the following composition was prepared as a surface size press solution.
Water: 83 parts by mass Surface sizing agent (Arakawa Chemical Industries, Polymeron 1355, solid content 25%): 6 parts by mass Oxidized starch (Ace A manufactured by Oji Cornstarch Co., Ltd.): 10 parts by mass Conductive agent (sodium sulfate): 1 part by mass Application An equal amount was applied to both sides of the base paper, dried and calendered so that the total amount was 1.5 g / m ² on both sides to obtain a recording paper having a basis weight of 65 g / m ² . In the same manner as in Example 1, the oblique elongation at break, the maximum point load in the oblique direction until the break, and the thickness of the paper were measured, and the oblique direction of the recording paper of Comparative Example 4 at 23 ° C. and 65% RH humidity control was measured. The elongation (mm) / thickness (mm) at break was 35, and the maximum load (N) / thickness (mm) until break was 155. The results are shown in Table 2.

<Comparative Example 5>
A recording paper of Comparative Example 5 was prepared in the same manner as in Example 2 except that the amount of polyethylene fiber (Dyneema SK60: manufactured by Toyobo) was 5 parts by mass and the amount of filler was 5 parts by mass. In the same manner as in Example 1, the oblique elongation at break, the maximum point load in the oblique direction until the break, and the thickness of the paper were measured, and the oblique direction of the recording paper of Comparative Example 5 at 23 ° C. and 65% RH humidity control was measured. The elongation (mm) / thickness (mm) at break was 20, and the maximum load (N) / thickness (mm) until break was 210. The results are shown in Table 2.

<Comparative Example 6>
A recording paper of Comparative Example 6 was prepared in the same manner as in Example 1 except that the basis weight was 40 g / m ² . In the same manner as in Example 1, the oblique elongation at break, the maximum point load in the oblique direction until the break, and the thickness of the paper were measured, and the recording paper of Comparative Example 6 was observed in the oblique direction at 23 ° C. and 65% RH humidity control. The elongation (mm) / thickness (mm) at break was 28, and the maximum load (N) / thickness (mm) until break was 216. The results are shown in Table 2.

<Comparative Example 7>
A recording paper of Comparative Example 7 was prepared in the same manner as in Example 1 except that the basis weight was 95 g / m ² . In the same manner as in Example 1, the oblique elongation at break, the maximum point load in the oblique direction until the break, and the thickness of the paper were measured, and the oblique direction of the recording paper of Comparative Example 7 at 23 ° C. and 65% RH humidity control was measured. The elongation (mm) / thickness (mm) at break was 32, and the maximum load (N) / thickness (mm) until break was 266. The results are shown in Table 2.

<Comparative Example 8>
The recording paper of a commercially available Kishu recycled PPC paper comparative example 8 was used. In the same manner as in Example 1, the oblique elongation at break, the maximum point load in the oblique direction until the break, and the thickness of the paper were measured, and the oblique direction of the recording paper of Comparative Example 8 at 23 ° C. and 65% RH humidity control was measured. The elongation (mm) / thickness (mm) at break was 32, and the maximum load (N) / thickness (mm) until break was 193. The results are shown in Table 2.

[Evaluation of recording paper]
For the recording papers of Examples 1 to 7, Reference Examples and Comparative Examples 1 to 8, curling after fixing was evaluated using DocuPrint 305 manufactured by Fuji Xerox Co., Ltd. as an electrophotographic recording apparatus. The results are shown in Tables 1 and 2. Note that this apparatus applies so-called ultra-small electronic devices with a main body volume of 0.07 m ³ excluding the paper feed and paper discharge trays when tension is applied to the paper at the time of fixing in a direction that slightly spreads to the left and right with respect to the paper feed direction. It is a photo recording device.

  In addition, the recording paper of each Example and each comparative example used for the evaluation is cut into A4 size (210 × 297) mm so that the longitudinal direction is the MD direction. Paper was fed in the paper feed direction.

[Curl evaluation after fixing]
The curling evaluation methods and evaluation criteria after fixing shown in Tables 1 and 2 are as follows. First, a document having an image density of 5% is printed in a single black color using each of the recording papers of the example and the comparative example, which is conditioned at 23 ° C. and 65% RH for 15 hours. At this time, 10 sheets of each recording sheet are continuously printed. Immediately after printing, the sample was placed on a flat measuring table, the linear distance between the recording sheet and the measuring table surface was measured at the four corners of the recording sheet from the measuring table, and the value with the largest distance was evaluated as the curl height after fixing. . The evaluation criteria are as follows, and ◎ and ○ are acceptable.
◎: Less than 10 mm ○: 10 mm to less than 20 mm △: 20 mm to less than 30 mm ×: 30 mm or more

From Table 1 and Table 2, when printing was performed with the electrophotographic recording apparatus using the electrophotographic recording sheets of Examples 1 to 7 , compared to the case of using the electrophotographic recording sheets of Comparative Examples 1 to 8. It can be seen that curling after fixing is reduced. In particular, it can be seen that the characteristics are excellent when the electrophotographic recording paper of Example 7 is used.

It is the schematic explaining the diagonal direction of the paper in embodiment of this invention.

Explanation of symbols

10 Paper.

Claims (1)

An electrophotographic recording paper mainly composed of pulp fibers,
Includes a synthetic fiber comprising polyethylene resin, and a filler,
The basis weight of the paper is 45 to 90 g / m ² ,
The fiber orientation ratio of the paper is 1.4 or less,
The content of the filler in the paper is 2 to 3% by mass ,
The relationship between the breaking elongation in the oblique direction and the thickness of the paper conditioned at 23 ° C. and 65% RH,
Elongation at break (mm) / Thickness (mm) ≦ 30
And the relationship between the maximum point load and the thickness until breakage is
Maximum point load (N) / thickness (mm) ≧ 220
An electrophotographic recording paper characterized by the above.

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