JP2008116842A - Recording paper sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a recording paper sheet capable of reducing its curlling even when its moisture is high. <P>SOLUTION: In the recording paper sheet using at least cellulose pulp as raw material, permanent set ε in a CD direction of the paper sheet expressed by a following expression is within 0.001 to 0.050%. The permanent set ε(%) in the CD direction of the paper sheet = (ΔL/L)×100. In the expression, ΔL expresses the dimensional variable (μm) of a paper sheet sample having 4 mm width and 30 mm length, which is obtained three seconds after maximum value of tensile stress is applied when the tensile stress is released to 0.0025 N/mm<SP>2</SP>at the speed of 15 N/sec immediately after the tensile stress is applied to 1.4 N/mm<SP>2</SP>at the speed of 15 N/sec after the paper sheet sample is left under environment of 50°C and 65% RH as it is for twenty minutes while the tensile stress of 0.0025 N/mm<SP>2</SP>is applied thereto, and L expresses the initial dimension (μm) of the paper sheet sample. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a recording paper (hereinafter sometimes referred to as “paper”).

  Conventionally, after fixing with an electrophotographic recording method (electrophotographic method) copying machine or printer, the paper curls, causing problems such as paper jams at the time of copying and poor capacity of post-processing devices such as mis-stitching. There was a thing. In particular, recent copiers and printers have become more complex, such as downsizing, automatic double-sided copying, and automatic bookbinding. Therefore, in the conventional technique, the curl after heat fixing becomes large, and the end of the sheet may come into contact with a member in the machine and a paper jam or the like is likely to occur.

  Due to the above problems, various studies have been made to reduce curling in the electrophotographic recording system. For example, paying attention to the characteristic difference between the paper layers on the front and back of the transfer paper, a method for controlling the difference in expansion / contraction ratio between the front and back of the paper has been proposed (for example, see Patent Document 1).

  In addition, in electrophotographic recording type copiers and printers, when toner is heat-fixed, high pressure is applied and the paper is deformed, which may cause curling, and requires strong paper strength. Paying attention to the strength of the paper, for example, Patent Document 2 uses chitosan and Patent Document 3 uses polyacrylamide to reinforce the weak paper. These increase the amount of hydrogen bonding as a mechanism for reinforcing strength, and increase the strength of the paper by increasing the contact area between the fibers.

Japanese Patent Laid-Open No. 3-236062 JP-A-11-174719 JP-A-11-227346

  The present invention is a recording paper that can reduce curl even if the paper moisture is high, not only in an electrophotographic recording system but also in an inkjet recording system.

The present invention is a recording paper in which at least cellulose pulp is used as a raw material, and the CD-direction permanent strain ε of the paper represented by the following formula is in the range of 0.001 to 0.050%.
Permanent distortion in CD direction of paper ε (%) = (ΔL / L) × 100
(In the above formula, ΔL is a paper sample having a width of 4 mm and a length of 30 mm, left at 20 ° C. under a tensile stress of 0.0025 N / mm ^{2 in} a 50 ° C./65% RH environment, and then 1 at a rate of 15 N / sec. immediately after applying a tensile stress to .4N / mm ^2, when releasing the tension at a rate of 15N / sec to 0.0025 / mm ² stress, tensile dimension of the sheet sample 3 seconds after applying a maximum value of the stress (L represents the initial size (μm) of the paper sample.)

In the recording paper, the recording paper includes a base material, or a base material and a coating layer, and at least one of the base material and the coating layer contains a compound represented by the following structural formula It is preferable to do.
Ti (OR) _4-n (OR ') _n
(In the above structural formula, R represents a substituent combined with the compound, R ′ represents a polymer chain constituting the recording paper, and n represents an integer of 1 to 4.)

  In the recording paper, the recording paper preferably includes a base material, or a base material and a coating layer, and at least one of the base material and the coating layer preferably contains a thermosetting material.

  According to the first aspect of the present invention, it is possible to provide a recording sheet that can reduce curling even when the sheet moisture is high, as compared with the case where the present configuration is not provided.

  According to the second aspect of the present invention, it is possible to provide a recording sheet that can further reduce curling after fixing even when the sheet moisture is high as compared with the case where the present configuration is not provided.

  According to the third aspect of the present invention, it is possible to provide a recording sheet that can further reduce curling after fixing even when the sheet moisture is high as compared with the case where the present configuration is not provided.

  Embodiments of the present invention will be described in detail, roughly divided into recording sheets and image recording methods. The present invention is not limited to the following examples.

<Recording paper>
As a result of intensive studies to reduce the curl of the paper, the present inventors have found that the curl reduction effect does not function sufficiently with the conventional technology as described above. Also, in electrophotographic recording copiers and printers, pressure is applied when toner is heat-fixed, which can deform the paper and cause curling and paper jams. Strong paper strength is required. Yes. In particular, when the production speed is increased in order to increase the productivity of the paper, the fiber orientation ratio of the paper is increased at the same time, and the strength in the direction perpendicular to the CD (short for Cross Direction) direction, that is, the direction in which the paper machine proceeds is increased. It will drop more. In addition, when used paper is used as a raw material, the strength of the pulp is lowered, and the strength in the CD direction of the paper is lowered. In order to reinforce these, as a conventional technique, the strength of the paper is reinforced by adding a material such as polyacrylamide, chitosan, and bacterial cellulose to increase the paper strength by increasing the amount of hydrogen bonds. However, in these technical ranges, there is a reinforcing effect, but since the amount of hydrogen bonding is increased, it is affected by moisture and the strength of the paper is greatly reduced. As a result, the curl becomes large and the strength cannot be improved. Therefore, by taking measures to control the CD permanent deformation ε of the paper measured under specific conditions within the range of 0.001 to 0.050%, the strength of the high moisture paper can be greatly reinforced, It has been found that can be greatly reduced. Further, since the strength of the paper is also improved, it has been found that the winding around the fixing device and the winding around the transfer belt are reduced, and that the copying machine or the printer can run more stably.

In other words, there is nothing other than the technology of the present embodiment that can achieve high moisture paper strength improvement. That is, the recording paper according to the present embodiment uses at least cellulose pulp as a raw material, and the CD-direction permanent strain ε of the paper represented by the following formula is in the range of 0.001 to 0.050%.
Permanent distortion in CD direction of paper ε (%) = (ΔL / L) × 100
(In the above formula, ΔL is a paper sample having a width of 4 mm and a length of 30 mm, left at 20 ° C. under a tensile stress of 0.0025 N / mm ^{2 in} a 50 ° C./65% RH environment, and then 1 at a rate of 15 N / sec. immediately after applying a tensile stress to .4N / mm ^2, when releasing the tensile stress at a speed of 15N / sec to 0.0025 / mm ^2, the maximum value of the tensile stress (i.e., 1.4N / mm ²⁾ over (L represents the initial dimension (μm) of the paper sample.)

The CD direction permanent strain ε of the recording paper according to the present embodiment is measured using a thermomechanical analyzer (EXSTAR 6100 TMA / SS, manufactured by SII Nano Technology Co., Ltd.). FIG. 1 shows an outline of a thermomechanical analyzer (TMA). In FIG. 1, 10 is a recording sheet, 12 is a tension generating unit, 14 is a dimension detecting unit, 16 is a heating unit, 18 is a gripping tool, 20 is a tension probe, 22 is a heating and humidification chamber, 24 is a humidity air supply port, Reference numeral 26 denotes a humidity supply device. In the thermomechanical analyzer 1, the paper sample to be measured (recording paper 10) is held for 16 hours in an environment of 23 ° C. and 50% RH using the tension probe 20, and then the CD direction of the paper (paper manufacturing direction) The recording paper 10 is gripped so that the distance between the two grippers 18 is 20 mm, and the tension probe 20 is set. Then, the warming / humidification chamber 22 is raised, and the tension probe 20 is sealed in the warming / humidification chamber 22. Thereafter, the inside of the heating and humidifying chamber 22 is heated to 50 ° C. while applying a tensile stress of 0.0025 N / mm ² , and humidity air is applied from the humidity supply device 26 through the humidity air supply port 24 to 65% RH. After supplying into the warm and humid chamber 22 and holding the 50 ° C./65% RH environment for 20 minutes, immediately after applying a tensile stress to 1.4 N / mm ² at a rate of 15 N / sec, 0 at a rate of 15 N / sec. Release the tensile stress to 0025 N / mm ² . The CD permanent set amount ΔL represents the dimensional change (μm) of the recording paper 10 3 seconds after the maximum tensile stress is applied, L represents the initial dimension (μm) of the recording paper 10, and the CD direction. The permanent strain ε (%) = (ΔL / L) × 100 is used to calculate ε (%). FIG. 2 shows an example of a measurement graph by a thermomechanical analyzer (TMA).

  The CD permanent set ε is 0.001% or more and 0.050% or less, preferably 0.020% or more and 0.040% or less, more preferably 0.020% or more and 0.030% or less. When the permanent distortion ε in the CD direction is less than 0.001%, in an electrophotographic recording type copying machine that winds a paper around a transfer device, the paper is too stiff and the paper does not follow the transfer device, resulting in a transfer failure. It may occur or bookbinding may not be properly performed. On the other hand, if the CD-direction permanent strain ε is larger than 0.050%, the paper is easily deformed when pressure is applied during heat fixing, which may cause curling or paper jam.

  In the present embodiment, in order to set the CD-direction permanent strain ε of the recording paper in the range of 0.001 to 0.050%, a material that introduces bonds other than hydrogen bonds is used as the base material or coating layer of the recording paper, Alternatively, it is preferable to internally add or apply to the base material and the coating layer of the recording paper. There is no worry about thickening of the coating solution by the internal addition method. Examples of such materials include crosslinkers, reactants, adhesives, thermosetting, which can reinforce the cellulose, which is the main component of the paper, with bonds other than hydrogen bonds, such as covalent bonds, ionic bonds, van der Waals bonds, etc. An agent or the like can be used.

  Specific examples of the crosslinking agent, the reactive agent, and the adhesive, which are materials capable of introducing bonds other than hydrogen bonds, include water-soluble metal salt compounds having crosslinking ability, such as ammonium zirconium carbonate, Compounds such as titanium compounds, glycidyl ethers with epoxy groups, polyamide epoxy resins, MDI (diphenylmethane diisocyanate) with isocyanate groups, HMDI (dicyclohexylmethane diisocyanate), etc. Glyoxal, glutaraldehyde, formaldehyde compounds When heated, the reaction proceeds between the cellulose chains of the recording paper, a three-dimensional structure is formed, and it has the property of being cured in an infusible state even by reheating, stabilizing the form and reinforcing the strength If possible, this does not apply, but the coating solution HDMI, zirconium carbonate, titanium compounds such as water-soluble titanium compounds, polyamide epoxy resins are preferred from the viewpoints of ease of use such as being hard to stick, color, thermosetting temperature, strength, safety, etc. Water-soluble titanium compounds, etc. The titanium compound is more preferable.

Specific examples of titanium compounds contained in recording paper include the following structural formulas:
Ti (OR) _4-n (OR ') _n
(In the above structural formula, R represents a substituent compounded with the titanium compound, R ′ represents a polymer chain constituting the recording paper, and n represents an integer of 1 to 4.)
Examples thereof include water-soluble titanium compounds, titanium alkoxides, titanium acylates and the like. As a titanium compound, when heated, the reaction proceeds between the cellulose chains of the recording paper, and a three-dimensional structure is formed. Although it is not limited as long as it can be reinforced, a water-soluble titanium compound is preferable from the viewpoints of ease of use such as the coating liquid being hard to thicken, color, thermosetting temperature, strength, safety, etc., and temperature-sensitive water-soluble titanium. Compounds are more preferred.

The water-soluble titanium compound is Ti— (O—R) ₄ (R is a linear or branched alkoxy group, an alkylthio group, an unsubstituted or substituted arylthio group, a triethanolamino group, a lactic acid group, a hydroxyl group, or the like. And is preferably a straight-chain, branched, or cyclic structure having 1 to 5 carbon atoms.) And is a compound that crosslinks with a hydroxyl group of cellulose of paper by heating. The water-soluble titanium compound is preferably a temperature-sensitive titanium compound that undergoes a rapid crosslinking reaction when a certain temperature threshold is exceeded by heating. The temperature-sensitive titanium compound is stable at room temperature but has a characteristic of causing a crosslinking reaction only at a specific temperature, and is used together with an auxiliary agent that temporarily suppresses the reaction. By using a temperature-sensitive titanium compound, crosslinking can be reliably performed with a small amount of use, and thickening of the coating liquid can be suppressed. From the viewpoint of handleability and the like, the crosslinking temperature of the titanium compound is preferably in the range of about 90 ° C to 120 ° C.

  Further, in this embodiment, in order to set the CD-direction permanent strain ε of the recording paper in the range of 0.001 to 0.050%, the substance to be included in the recording paper may be a thermosetting material. Thermosetting materials cure irreversibly when a certain temperature is applied, that is, by heating, a complex reaction proceeds between the polymer chains, forming a three-dimensional structure, and reheating. Is a material having a property of being cured so as to be in an infusible state. In the case of thermosetting materials, even when stress is applied to high moisture paper during fixing in an electrophotographic image forming apparatus, the thermosetting material forms a strong bond between the cellulose pulp of the recording paper. The form stability of the moisture paper is improved and curling is less likely to occur. Further, in the case of a conventionally used water-soluble paper strength enhancer (for example, polyacrylamide), in a high-humidity environment, water molecules enter between hydrogen bonds formed with cellulose fibers, thereby recording paper. However, since the thermosetting material has low sensitivity to water, the decrease in strength of the recording paper is small, and the phenomenon that the recording paper is wound around the fixing member in the fixing device hardly occurs.

  Such thermosetting materials include phenolic resins, epoxy resins, melamine resins, urea resins, unsaturated polyester resins, alkyd resins, xylene resins, thermosetting polyurethane, and other synthetic resins, β- Natural products such as 1,3-glucan, β-1,3-glucan derivatives, proteins, casein, phenol derivatives of natural lignin, shellac (sometimes called shellac), urushiol, or extracts of natural products or If natural derivatives can be used and permanent deformation of the paper can be suppressed, it is not limited to this. However, from the viewpoint of environmental load, disaggregation at the time of paper regeneration, color, thermosetting temperature, paper strength increase, etc., β-1 , 3-glucan, shellac, or β-1,3-glucan derivative, shellac derivative is preferably selected.

  In this embodiment, in order to make the CD permanent distortion ε of the recording paper in the range of 0.001 to 0.050%, the recording paper contains a material for introducing a bond other than the hydrogen bond and a thermosetting material. May be.

  The material for introducing bonds other than hydrogen bonds in this embodiment preferably reacts with the cellulose of the paper, but non-reacted portions may remain. Moreover, although it is preferable that the thermosetting material is thermosetting, the non-hardened part may remain. As a confirmation method in that case, a pyrolysis gas chromatography (GC) -mass spectrometer (MASS) is used to determine whether a reaction-derived compound and a paper constituent material, a Ti-derived compound and a paper constituent material such as cellulose or oxidized starch are used. The bound substance may be identified, or the paper may be decomposed with cellulase and then derivatized and separated and identified with GC-MASS. In addition, the paper is pulverized with an infrared spectrometer (IR), dehydrated with silica gel, etc., mixed well with KBr powder, tableted with a tablet former, measured for infrared absorption spectrum, reaction It may be confirmed that there is an absorption wavelength derived from a structure in which cellulose or oxidized starch is bonded to a material and a paper constituent material, titanium and a paper constituent material, for example, a reactive material. Further, after the paper is well dehumidified, an infrared absorption spectrum may be measured by an ATR (Attenuated Total Reflection) method. Further, after extraction with alkaline cold water or hot water, separation and identification may be performed by liquid chromatography (LC), gas chromatography (GC) or the like.

In the present embodiment, the total content of the material for introducing bonds other than hydrogen bonds and the thermosetting material in the recording paper is preferably 0.1 g / m ² or more and 10.0 g / m ² or less. More preferably, it is 5 g / m ² or more and 5.0 g / m ² or less. When the content exceeds 10.0 g / m ² , the absolute amount of the material is large and it becomes difficult to recycle the paper, and the paper strength becomes too high and paper jam is likely to occur. The rate becomes low and toner transfer failure tends to occur. Further, when the processing amount is less than 0.1 g / m ² , the absolute amount of the material is small, and the CD-direction permanent strain ε is not reduced, and when the recording paper is run with an electrophotographic recording type copying machine or the like, The curl may become large.

The recording paper according to this embodiment may be treated with a surface sizing agent. The surface size liquid is mainly composed of a solvent such as water, and the concentration of the surface size liquid is preferably in the range of 5 to 15% by mass, more preferably in the range of 8 to 12% by mass. The amount applied by the surface size liquid is preferably in the range of 0.1 to 3.0 g / m ² , more preferably in the range of 1.0 to 2.0 g / m ² per one side of the recording paper. . When the treatment amount exceeds 3.0 g / m ² , the absolute amount of the surface sizing agent is large, the curl reduction effect is inhibited, and the curl may be increased. On the other hand, when the amount is less than 0.1 g / m ² , the absolute amount of the surface sizing agent is small, and the pigment applied together with the surface sizing agent cannot be fixed on the paper surface. In some cases, a large amount of paper dust is generated, causing trouble to the machine.

  Specifically, as the surface sizing agent in this embodiment, among the surface sizing agents, not only oxidized starch usually used as a surface sizing agent, but also starch modified with an enzyme (enzyme-modified starch), improving hydrophobicity Acetylated starch, phosphate esterified starch and the like may be used. In order to reduce hydrophilic carboxyl groups from the viewpoint of hydrophobicity of the surface sizing agent, starch, acetylated starch, siliconized starch and the like obtained by modifying starch with an enzyme are preferable to conventionally used oxidized starch. Further, polyvinyl alcohol having a very low saponification degree to leave a hydrophobic group or an extremely high saponification degree to improve the crystallinity and improve the hydrophobicity is also preferably used. In addition, for the purpose of improving the image quality in the ink jet method, polyvinyl alcohol having a low polymerization degree may be used. Furthermore, a silanol-modified surface sizing agent with improved hydrophobicity may be used, and these may be mixed or used alone.

  The CD expansion / contraction rate of the recording paper in this embodiment is preferably 0.70 or less, and more preferably 0.30 to 0.60%. The CD expansion / contraction rate is defined as the humidity of “65% RH → 25% RH → 65% RH → when the recording paper is left in a constant temperature environment maintained at 23 ° C. → The moisture absorption / desorption treatment with a change of “90% RH” was repeated three cycles, and the recording paper dimensions when the humidity was changed from “65% RH → 25% RH” in the third cycle. It means the rate of change. The dimensions of the recording paper can be measured using an OH Engineering H / K type elasticity tester. Note that “CD (direction)” is a direction crossing the flow direction at the time of recording paper manufacture, and when measuring the dimensions of the recording paper, the dimension in the direction crossing the flow direction at the time of recording paper manufacture is measured. In order to control the CD expansion / contraction rate (%) of the paper to 0.70 or less, preferably in the range of 0.30 to 0.60%, the method according to the above-mentioned form stabilizing effect of the present embodiment, the beating of the pulp to be used is weakened Highly free pulp is used as raw material, keratinized pulp is used as raw material, basis weight is increased, dry paper strength enhancer is added, paper thickness is increased, sizing agent / filler inside paper And a method of reducing the wet press pressure, reducing the fiber orientation ratio, and the like. Under the present circumstances, the freeness of the pulp in this embodiment is Canadian standard freeness, and is the value measured by the measuring method according to JIS-P-8121.

  The recording paper of this embodiment preferably has a formation index of 10 to 50, more preferably 15 to 40. If the formation index is less than 10, formation unevenness tends to cause uneven image transfer in the electrophotographic recording method. Further, when the formation index exceeds 50, it is necessary to strengthen the beating of the paper in order to ensure the homogeneity, and the curl may be increased. Here, the formation index is M / K Systems, Inc. A 3D sheet analyzer (M / K950) manufactured by (MKS) was used, the aperture of the analyzer was 1.5 mm in diameter, and measurement was performed using a micro formation tester (MFT). That is, a sample is mounted on a rotating drum in a 3D sheet analyzer, and a local basis weight difference in the sample is detected by a light source attached to the drum shaft and a photodetector attached to the outside of the drum corresponding to the light source. Measure as The measurement target range at this time is set by the diameter of the diaphragm attached to the light incident portion of the photodetector. Next, the light intensity difference (deviation) is amplified, A / D converted, classified into 64 photometric basis weight classes, 1000000 data are taken in one scan, and the histogram frequency for the data is obtained. obtain. Then, the highest frequency (peak value) of the histogram is divided by the number of classes having a frequency of 100 or more out of those classified into classes corresponding to a micro basis weight of 64, and the value obtained by dividing it by 1/100 is the ground index. Calculated. This texture index indicates that the greater the value, the better the texture.

In the electrophotographic recording method, the electrical characteristics of the paper are important.In particular, in the present embodiment, surfactants and cationized materials that can change the electrical characteristics of the paper are frequently used, and depending on the combination and content thereof, Image transfer unevenness may occur in the electrophotographic recording method. Therefore, in this embodiment, the surface resistivity of at least the printing surface of the recording paper is in the range of 1.0 × 10 ⁹ to 1.0 × 10 ¹¹ Ω / □, and the volume resistivity of the recording paper is 1. The above-mentioned problem can be avoided by defining it in the range of 0 × 10 ¹⁰ to 1.0 × 10 ¹² Ω · cm, which is preferable. If it is not within the above range, uneven image transfer may occur in the electrophotographic recording method.

In the recording paper used in this embodiment, at least the surface resistivity of the printed surface is preferably in the range of 1.0 × 10 ⁹ to 1.0 × 10 ¹¹ Ω / □, and 5.0 × 10 ^9. To 7.0 × 10 ¹⁰ Ω / □, and more preferably 5.0 × 10 ⁹ to 2.0 × 10 ¹⁰ Ω / □. The surface electrical resistivity indicates the resistance of a surface formed by applying a polyvalent metal salt and / or a cationic resin. The volume electrical resistivity of the recording paper used in the present embodiment is preferably in the range of 1.0 × 10 ¹⁰ to 1.0 × 10 ¹² Ω · cm, and 1.0 × 10 ¹⁰ to 1.6. It is more preferably in the range of × 10 ¹¹ Ω · cm, and further preferably in the range of 1.3 × 10 ¹⁰ to 4.3 × 10 ¹⁰ Ω · cm.

  In addition, the said surface resistivity and volume resistivity are measured by the method based on JIS-K-6911 which preserve | saved for 24 hours on the conditions of 23 degreeC50% RH, and adjusted the humidity.

  The recording paper in the present embodiment is at least cellulose pulp as a raw material, and may be the following base paper, or may be plain paper in which the surface of the base paper is treated with a pigment or a binder. Good. Moreover, the coated paper (coated paper) which gave the coat layer (coating layer) containing a pigment after performing size press to a base material may be sufficient. The base paper contains cellulose pulp, but known cellulose pulp can be used. Chemical pulp, specifically, hardwood bleached kraft pulp, hardwood unbleached kraft pulp, softwood bleached kraft pulp, softwood unbleached Kraft pulp, hardwood bleached sulfite pulp, hardwood unbleached sulfite pulp, softwood bleached sulfite pulp, pulp made by chemically treating wood and fiber materials such as cotton, hemp, and hulls can be used.

  In addition, ground wood pulp obtained by mechanically pulping wood and chips, chemimechanical pulp obtained by mechanically pulping wood and chips and then mechanically pulped, thermomechanical pulp, and the like can also be used. These may be used only with virgin pulp, or waste paper pulp may be added as necessary.

  In particular, pulp used in virgin is bleached mainly using ozone / hydrogen peroxide without using chlorine gas and without using chlorine gas (Elementary Chlorine Free; ECF) or chlorine compounds. It is preferably one that has been bleached by a method (Total Chlorine Free; TCF).

  In addition, as a raw material of the waste paper pulp, there are unprinted waste paper such as cuts, damaged paper, widened white, special white, medium white, white loss generated in bookbinding, printing factories, cutting offices, etc .; Used high-quality paper, high-quality coated paper and other high-quality printed old paper; Water-based ink, oil-based ink, old paper written with pencils, etc .; Waste paper containing medium; used paper such as medium-quality paper, medium-quality coated paper, and reprint paper; and the like.

  The waste paper pulp used for the base paper used in this embodiment is preferably one obtained by treating the waste paper raw material with at least one of ozone bleaching treatment and hydrogen peroxide bleaching treatment. Moreover, in order to obtain a base paper with higher whiteness, it is preferable that the ratio of the waste paper pulp obtained by the bleaching treatment is 50% or more and 100% or less. Furthermore, from the viewpoint of resource reuse, it is more preferable that the ratio of the used paper pulp is 70% or more and 100% or less.

  The ozone treatment has an action of decomposing fluorescent dyes or the like usually contained in fine paper, and the hydrogen peroxide treatment prevents yellowing due to alkali used during deinking treatment. In particular, the combination of these two processes not only facilitates the deinking of waste paper, but also improves the whiteness of the pulp. Moreover, since it also has an action of decomposing and removing residual chlorine compounds in the pulp, it has a great effect in reducing the content of organic halogen compounds in the waste paper using chlorine bleached pulp.

  In addition, it is preferable to add a filler to the recording paper according to the present embodiment in order to adjust opacity, whiteness, and surface property. In particular, when it is desired to reduce the amount of halogen in the paper, it is preferable to use a filler that does not contain halogen. Fillers that can be used include heavy calcium carbonate, light calcium carbonate, kaolin, calcined clay, talc, titanium dioxide, zinc oxide, aluminum silicate, synthetic silica, aluminum hydroxide, alumina, sericite, saponite, bentonite, etc. Mention may be made of pigments and organic pigments such as plastic pigments, polyethylene, urea resins and the like. Moreover, when mix | blending waste paper, it is necessary to estimate the ash content contained in a waste paper raw material previously, and to adjust addition amount.

  Furthermore, it is preferable to add an internal sizing agent to the paper used in the present embodiment. As the internal sizing agent, a neutral rosin sizing agent used for neutral papermaking, alkenyl succinic anhydride (ASA). ), Alkyl ketene dimers (AKD), and petroleum resin sizing agents can be used.

  In addition, when the surface of the recording paper is adjusted to be cationic, for example, a hydrophilic cationic resin can be treated on the surface as a cationic substance, but the penetration of the cationic resin into the inside is suppressed. In order to achieve this, it is preferable that the paper sizing degree before applying the cationic resin is 10 seconds or more and less than 60 seconds.

  The recording paper of this embodiment can be obtained by surface-treating the surface size liquid on the recording paper as described above. The surface treatment is performed by applying the surface sizing liquid to the paper by a commonly used application means such as a size press, shim size, gate roll, roll coater, bar coater, air knife coater, rod blade coater, blade coater, etc. Can do. Thereafter, the recording paper of this embodiment can be obtained through a drying process.

The basis weight of the recording paper of the present embodiment is not particularly limited, and is preferably in the range of 60 to 128 g / ^{m 2,} more preferably in the range of 60 to ^{100g / m 2, 90g / m} 2 to 60 It is more preferable to be within the range. The higher the basis weight, the more advantageous for curling and undulation, but if the basis weight exceeds 128 g / m ² , the paper is too stiff and the paper runnability of a printer or the like may be reduced. ^{On the other hand, when} it is lower than 60 g / m ² , it is difficult to suppress the occurrence of curling, and it is not preferable from the viewpoint of set-off.

The fiber orientation ratio of the recording paper in the present embodiment is the fiber orientation ratio by the ultrasonic propagation velocity method, and the ultrasonic propagation velocity in the MD direction of the paper (traveling direction of the paper machine) is defined as the CD direction of the paper (paper machine). The value divided by the ultrasonic wave propagation velocity in the direction perpendicular to the traveling direction of (1) is expressed by the following equation.
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 The fiber orientation ratio by this ultrasonic wave propagation speed method is SonicSheetTester210 (Nomura Corporation) )). The recording paper of this embodiment preferably has a fiber orientation ratio of 1.1 to 1.8, and more preferably 1.2 to 1.7.

  The recording paper according to the present embodiment has a small curl even when used in an electrophotographic copying machine or printer, particularly a copying machine or printer that is downsized and multifunctional, and can significantly reduce paper jams. it can. In particular, it is possible to improve the running reliability of the recording paper when it is applied in a high humidity environment to a copying machine or printer having a mechanism in which more heat is applied from the fixing mechanism to one side of the paper. In addition, even when the recording paper according to the present embodiment is used in an ink jet recording system or the like, the change in paper dimensions can be suppressed, so that paper jam during double-sided copying / printing can be greatly reduced. That is, the transfer paper according to the present embodiment (1) can curl when printed using this, and (2) when used in an electrophotographic recording system, the wrap around the fixing device is almost not. Does not occur. For this reason, not only the curl of the paper becomes small, but also the paper can be outputted without paper jam in the output machine.

<Image recording method>
(Electrophotographic recording type image recording method)
The image recording method according to this embodiment includes a charging step for uniformly charging the surface of the electrostatic latent image carrier, an exposure step for exposing the surface of the electrostatic latent image carrier to form an electrostatic latent image, and the static The electrostatic latent image formed on the surface of the electrostatic latent image carrier is developed using an electrostatic charge image developer to form a toner image, the transfer step of transferring the toner image to the recording paper surface, A fixing process for fixing the toner image on the surface of the recording paper, and the recording paper is the recording paper.

  In the electrophotographic recording type image recording method of the present embodiment, by using the recording paper, a high-quality image can be obtained as in the conventional case, and curling that occurs immediately after printing can be suppressed.

  In addition, the image forming apparatus used in the electrophotographic recording method image recording method in the present embodiment is one that uses the electrophotographic recording method having the charging step, the exposure step, the developing step, the transfer step, and the fixing step. There is no particular limitation. For example, when four color toners of cyan, magenta, yellow, and black are used, a four-cycle development system in which a developer containing each color toner is sequentially applied to one photoreceptor to form a toner image. Or a color image forming apparatus (so-called tandem machine) provided with four developing units corresponding to each color can be used.

  The toner used for image formation is not particularly limited as long as it is a known toner. For example, in order to obtain a highly accurate image, a spherical toner having a small particle size and particle size distribution is used, and energy saving is supported. In addition, a toner containing a binder resin having a low melting point that can be fixed at a low temperature can be used.

(Inkjet recording type image recording method)
The image recording method according to the present embodiment is an ink jet recording type image recording method in which ink droplets are ejected onto a recording sheet to record an image on the surface of the recording sheet, and the recording sheet is the recording sheet.

  As long as the ink jet recording method in the present embodiment is a known ink jet apparatus, good print quality can be obtained regardless of which ink jet recording method is used. Furthermore, for a system having a function of promoting the absorption and fixing of ink by providing heating means such as recording paper during printing or before and after printing, and heating the recording paper and ink at a temperature of 50 ° C. to 200 ° C. In addition, the ink jet recording method in the present embodiment can be applied.

  Next, an example of an ink jet recording apparatus suitable for carrying out the ink jet recording method in the present embodiment will be described. This example is a so-called multi-pass method, in which an image is formed by a recording head scanning the surface of a recording sheet a plurality of times.

  As a method for ejecting ink from a nozzle, there is a so-called thermal ink jet method in which ink in a nozzle is foamed by energizing and heating a heater provided in the nozzle, and the ink is ejected by the pressure. There is also a method in which a piezoelectric element is electrically deformed to physically deform the element, and ink is ejected from the nozzles using a force generated by the deformation. In this system, a piezoelectric element using a piezo element is typical. In the ink jet recording apparatus used in the ink jet recording method in the present embodiment, the method of ejecting ink from the nozzles may be any of the above methods, and is not limited to these methods.

  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.

<Preparation of paper>
(Example 1)
The pulp dispersion was adjusted so that the solid content of the solid deinked pulp having a freeness of 380 mL was 0.3% by mass. In this pulp dispersion, succinic anhydride (ASA) -containing sizing agent (Nippon NSC Co., Ltd., Fibran-81) 0.3 parts by mass with respect to 100 parts by mass of pulp solids contained in the pulp dispersion And 0.5 parts by mass of cationized starch (NCAT Co., Ltd., Cato-304), and using an 80-mesh wire with an orientation paper machine for experiments made by Kumagai Riki Co., Ltd., a paper making speed of 1000 m / min. The paper was made under the condition of a paper discharge pressure of 1.5 kg / cm ² . After that, the set was squeezed for 3 minutes at 10 kgf / cm ² with a press for Kumagaya Riki's square sheet machine, and then dried at 120 ° C. and 0.5 m / min on a KRK rotary dryer manufactured by Kumagai Riki. A paper with an amount of 68 g / m ² was obtained. On this paper, as a surface size binder, oxidized starch (manufactured by Oji Cornstarch Co., Ltd., Ace A) 10 parts by weight of bow glass with respect to 100 parts by weight of solid content, 10 parts by weight of surface sizing agent (manufactured by Arakawa Chemical Industries, Ltd., Polymarlon 1355), 50 parts by mass of water-soluble titanium compound 1 (manufactured by Matsumoto Pharmaceutical Co., Ltd., ORGATICS TC-310, Ti— (O—R) ₄ (R is OH and C ₃ H ₅ O ₂ groups)), An aqueous solution (surface size solution) having a concentration of 8% by mass containing 30 parts by mass of β-1,3-glucan (trade name: Curdlan, manufactured by Takeda Kirin Foods Co., Ltd.), a titanium compound and a thermosetting material (β- 1,3 glucan) was size-pressed with a test size press manufactured by Kumagai Riki Co., Ltd. so as to have a content of 1.0 g / m ² , and then 120 ° C., 0.33 m / cm using a KRK rotary dryer manufactured by Kumagaya Riki Co., Ltd. mi Was dried at a basis weight to obtain a recording paper of 70g / ^{m 2} (1). FIG. 3 shows the measurement result of the permanent deformation ε in the CD direction using a thermomechanical analyzer (TMA). Table 1 shows the characteristic values of the recording paper. It confirmed that the covalent bond was formed between the titanium compound and the cellulose of a recording paper with the Fourier-transform infrared-spectral-analysis apparatus (The Perkin-Elmer Japan Co., Ltd. make, Spectrum1000).

(Example 2)
The pulp dispersion liquid was adjusted so that pulp solid content might become 0.3 mass% of LBKP with a freeness of 480 mL. In this pulp dispersion, succinic anhydride (ASA) -containing sizing agent (Nippon NSC Co., Ltd., Fibran-81) 0.3 parts by mass with respect to 100 parts by mass of pulp solids contained in the pulp dispersion And 0.5 parts by mass of cationized starch (NCAT Co., Ltd., Cato-304), and an orientation paper machine for experiments made by Kumagai Riki Co., Ltd., using an 80 mesh wire, making speed 1600 m / min. The paper was made under the condition of a paper discharge pressure of 1.5 kg / cm ² . After that, the set was squeezed for 3 minutes at 10 kgf / cm ² with a press for Kumagaya Riki's square sheet machine, and then dried at 120 ° C. and 0.5 m / min on a KRK rotary dryer manufactured by Kumagai Riki. A paper with an amount of 68 g / m ² was obtained. On this paper, as a surface size binder, oxidized starch (manufactured by Oji Cornstarch Co., Ltd., Ace A) 10 parts by weight of bow glass with respect to 100 parts by weight of solid content, 10 parts by weight of surface sizing agent (manufactured by Arakawa Chemical Industries, Ltd., Polymarlon 1355), 100 mass parts β-1,3-glucan (manufactured by Takeda Kirin Foods Co., Ltd., trade name: curdlan), 8% by weight aqueous solution (surface size liquid) is heated to 50 ° C. The size of the thermosetting material (β-1,3-glucan) was 0.59 g / m ^2, and was size-pressed with a size press for testing by Kumagai Riki Co., Ltd. It dried on 90 degreeC and 1.0 m / min conditions, and obtained the recording paper (2) whose basic weight is 70 g / m < ² >. FIG. 3 shows the measurement result of the permanent deformation ε in the CD direction using a thermomechanical analyzer (TMA). Table 1 shows the characteristic values of the recording paper.

(Example 3)
The pulp dispersion was adjusted so that the solid content of the solid deinked pulp having a freeness of 380 mL was 0.3% by mass. In this pulp dispersion, succinic anhydride (ASA) -containing sizing agent (Nippon NSC Co., Ltd., Fibran-81) 0.3 parts by mass with respect to 100 parts by mass of pulp solids contained in the pulp dispersion And 0.5 parts by mass of cationized starch (Nito SC Co., Ltd., Cato-304), and using an 80-mesh wire with an orientation paper machine for experiments made by Kumagai Riki Co., Ltd., making speed 1750 m / min. The paper was made under the condition of a paper discharge pressure of 1.5 kg / cm ² . After that, the set was squeezed for 3 minutes at 10 kgf / cm ² with a press for Kumagaya Riki's square sheet machine, and then dried at 120 ° C. and 0.5 m / min on a KRK rotary dryer manufactured by Kumagai Riki. A paper with an amount of 68 g / m ² was obtained. On this paper, as a surface size binder, oxidized starch (manufactured by Oji Cornstarch Co., Ltd., Ace C) 10 parts by weight of bow glass with respect to 100 parts by weight of solid content, 10 parts by weight of surface sizing agent (Arakawa Chemical Industries, Ltd., Polymeral 1355), 40 parts by weight of an aqueous shellac solution (Nihon Shellac Industrial Co., Ltd., SB # 25) and 10 parts by mass of a water-dispersible polyisocyanate (Dainippon Ink Chemical Co., Ltd., Bernock DNW-5000) , And size-pressed with a size press for testing by Kumagai Riki so that the amount of water-dispersible polyisocyanate and thermosetting material (shellac) on paper is 1.82 g / m ² . The recording paper (3) having a basis weight of 70 g / m ² was obtained by drying with a KRK rotary dryer at 120 ° C. and 1.0 m / min. FIG. 3 shows the measurement result of the permanent deformation ε in the CD direction using a thermomechanical analyzer (TMA). Table 1 shows the characteristic values of the recording paper.

Example 4
The pulp dispersion was adjusted so that the solid content of the solid deinked pulp having a freeness of 380 mL was 0.3% by mass. In this pulp dispersion, succinic anhydride (ASA) -containing sizing agent (Nippon NSC Co., Ltd., Fibran-81) 0.3 parts by mass with respect to 100 parts by mass of pulp solids contained in the pulp dispersion And 0.5 parts by mass of cationized starch (NCAT Co., Ltd., Cato-304), and an orientation paper machine for experiments made by Kumagai Riki Co., Ltd., using an 80 mesh wire, making speed 1600 m / min. The paper was made under the condition of a paper discharge pressure of 1.5 kg / cm ² . After that, the set was squeezed for 3 minutes at 10 kgf / cm ² with a press for Kumagaya Riki's square sheet machine, and then dried at 120 ° C. and 0.5 m / min on a KRK rotary dryer manufactured by Kumagai Riki. A paper with an amount of 68 g / m ² was obtained. On this paper, as a surface size binder, oxidized starch (manufactured by Oji Cornstarch Co., Ltd., Ace A) 10 parts by weight of bow glass with respect to 100 parts by weight of solid content, 10 parts by weight of surface sizing agent (manufactured by Arakawa Chemical Industries, Ltd., Polymeral 1355), 40 parts by weight of 40 parts by weight aqueous shellac solution (Nihon Shellac Industrial Co., Ltd., SB # 25) containing 8% by weight aqueous solution (surface size liquid) is heated to 50 ° C. and thermoset. After size-pressing with a Kumagaya Riki test size press so that the content of the material (shellac) is 0.15 g / m ² , 85 ° C. and 1.0 m / min conditions using a KRK rotary dryer made by Kumagai Riki And a recording paper (4) having a basis weight of 70 g / m ² was obtained. FIG. 3 shows the measurement result of the permanent deformation ε in the CD direction using a thermomechanical analyzer (TMA). Table 1 shows the characteristic values of the recording paper.

(Example 5)
The pulp dispersion was adjusted so that the solid content of the solid deinked pulp having a freeness of 380 mL was 0.3% by mass. In this pulp dispersion, succinic anhydride (ASA) -containing sizing agent (Nippon NSC Co., Ltd., Fibran-81) 0.3 parts by mass with respect to 100 parts by mass of pulp solids contained in the pulp dispersion And 0.5 parts by mass of cationized starch (NCAT Co., Ltd., Cato-304), and using an 80-mesh wire with an orientation paper machine for experiments made by Kumagai Riki Co., Ltd., a paper making speed of 1000 m / min. The paper was made under the condition of a paper discharge pressure of 1.5 kg / cm ² . After that, the set was squeezed for 3 minutes at 10 kgf / cm ² with a press for Kumagaya Riki's square sheet machine, and then dried at 120 ° C. and 0.5 m / min on a KRK rotary dryer manufactured by Kumagai Riki. A paper with an amount of 68 g / m ² was obtained. On this paper, as a surface size binder, oxidized starch (manufactured by Oji Cornstarch Co., Ltd., Ace A) 10 parts by weight of bow glass with respect to 100 parts by weight of solid content, 10 parts by weight of surface sizing agent (manufactured by Arakawa Chemical Industries, Ltd., Polymeral 1355), an aqueous solution (surface size liquid) having a concentration of 8% by mass containing 50 parts by mass of a water-soluble titanium compound 1 (manufactured by Matsumoto Pharmaceutical Co., Ltd., Olgatics TC-310), and a titanium compound content of 1. After size-pressing with a size press for testing made by Kumagaya Riki so as to be 0 g / m ² , it was dried at 120 ° C. and 0.33 m / min with a KRK rotary dryer made by Kumagai Riki, and the basis weight was 70 g / m. ² recording paper (5) was obtained. FIG. 3 shows the measurement result of the permanent deformation ε in the CD direction using a thermomechanical analyzer (TMA). Table 1 shows the characteristic values of the recording paper.

(Example 6)
The pulp dispersion liquid was adjusted so that pulp solid content might become 0.3 mass% of LBKP with a freeness of 480 mL. In this pulp dispersion, succinic anhydride (ASA) -containing sizing agent (Nippon NSC Co., Ltd., Fibran-81) 0.3 parts by mass with respect to 100 parts by mass of pulp solids contained in the pulp dispersion And 0.5 parts by mass of cationized starch (NCAT Co., Ltd., Cato-304), and an orientation paper machine for experiments made by Kumagai Riki Co., Ltd., using an 80 mesh wire, making speed 1600 m / min. The paper was made under the condition of a paper discharge pressure of 1.5 kg / cm ² . After that, the set was squeezed for 3 minutes at 10 kgf / cm ² with a press for Kumagaya Riki's square sheet machine, and then dried at 120 ° C. and 0.5 m / min on a KRK rotary dryer manufactured by Kumagai Riki. A paper with an amount of 68 g / m ² was obtained. On this paper, as a surface size binder, oxidized starch (manufactured by Oji Cornstarch Co., Ltd., Ace A) 10 parts by weight of bow glass with respect to 100 parts by weight of solid content, 10 parts by weight of surface sizing agent (manufactured by Arakawa Chemical Industries, Ltd., Polymarlon 1355), an 8 mass% aqueous solution (surface size liquid) containing 100 parts by mass of a temperature-sensitive water-soluble titanium compound (manufactured by Matsumoto Pharmaceutical Co., Ltd., T-2762), and heated to 50 ° C. After being size-pressed with a size press for testing manufactured by Kumagai Riki Co., Ltd. so that its content becomes 0.59 g / m ² , it is dried at 90 ° C. and 1.0 m / min using a KRK rotary dryer manufactured by Kumagai Riki Co., Ltd. A recording paper (6) having a basis weight of 70 g / m ² was obtained. FIG. 3 shows the measurement result of the permanent deformation ε in the CD direction using a thermomechanical analyzer (TMA). Table 1 shows the characteristic values of the recording paper.

(Example 7)
A recording paper (7) having a basis weight of 70 g / m ² was obtained in the same manner as in Example 6 except that LBKP having a freeness of 480 mL in Example 6 was changed to a medium-quality deinked pulp having a freeness of 380 mL. . FIG. 3 shows the measurement result of the permanent deformation ε in the CD direction using a thermomechanical analyzer (TMA). Table 1 shows the characteristic values of the recording paper.

(Example 8)
The pulp dispersion was adjusted so that the solid content of the solid deinked pulp having a freeness of 380 mL was 0.3% by mass. In this pulp dispersion, succinic anhydride (ASA) -containing sizing agent (Nippon NSC Co., Ltd., Fibran-81) 0.3 parts by mass with respect to 100 parts by mass of pulp solids contained in the pulp dispersion And 0.5 parts by mass of cationized starch (Nito SC Co., Ltd., Cato-304), and using an 80-mesh wire with an orientation paper machine for experiments made by Kumagai Riki Co., Ltd., making speed 1750 m / min. The paper was made under the condition of a paper discharge pressure of 1.5 kg / cm ² . After that, the set was squeezed for 3 minutes at 10 kgf / cm ² with a press for Kumagaya Riki's square sheet machine, and then dried at 120 ° C. and 0.5 m / min on a KRK rotary dryer manufactured by Kumagai Riki. A recording paper having an amount of 68 g / m ² was obtained. To this recording paper, as a surface size binder, oxidized starch (produced by Oji Cornstarch Co., Ltd., Ace C), 10 parts by weight of bow glass with respect to 100 parts by weight of solid content, 10 parts by weight of surface sizing agent (manufactured by Arakawa Chemical Industries, Ltd.) , Polymarlon 1355), an 8 mass% aqueous solution (surface size liquid) containing 1200 parts by mass of a temperature-sensitive water-soluble titanium compound (manufactured by Matsumoto Pharmaceutical Co., Ltd., T-2762) is heated to 50 ° C., and titanium The size of the compound on the paper is 1.82 g / m ² , and the size is pressed with a size press for testing by Kumagai Riki, then at 120 ° C. and 1.0 m / min with a KRK rotary dryer made by Kumagai Riki. And recording paper (8) having a basis weight of 70 g / m ² was obtained. FIG. 3 shows the measurement result of the permanent deformation ε in the CD direction using a thermomechanical analyzer (TMA). Table 1 shows the characteristic values of the recording paper.

Example 9
The pulp dispersion liquid was adjusted so that pulp solid content might become 0.3 mass% of LBKP with a freeness of 380 mL. In this pulp dispersion, succinic anhydride (ASA) -containing sizing agent (Nippon NSC Co., Ltd., Fibran-81) 0.3 parts by mass with respect to 100 parts by mass of pulp solids contained in the pulp dispersion And 0.5 parts by mass of cationized starch (manufactured by Nippon SC Co., Ltd., Cato-304) and 6 parts by mass of a temperature-sensitive water-soluble titanium compound (manufactured by Matsumoto Pharmaceutical Co., Ltd., T-2762) The mixture was blended, and the paper was made by an experimental orientation paper machine manufactured by Kumagai Riki under the conditions of a paper making speed of 1600 m / min and a paper discharge pressure of 1.5 kg / cm ² using an 80 mesh wire. The amount of titanium compound added to the paper was 2.5 g / m ² . After that, the set was squeezed for 3 minutes at 10 kgf / cm ² with a press for Kumagaya Riki's square sheet machine, and then dried at 120 ° C. and 0.5 m / min on a KRK rotary dryer manufactured by Kumagai Riki. A paper with an amount of 68 g / m ² was obtained. On this paper, as a surface size binder, oxidized starch (manufactured by Oji Cornstarch Co., Ltd., Ace C) 10 parts by weight of bow glass with respect to 100 parts by weight of solid content, 10 parts by weight of surface sizing agent (Arakawa Chemical Industries, Ltd., An 8% strength by weight aqueous solution (Polymeron 1355) containing an aqueous solution (surface sizing solution) is heated to 50 ° C. and sized with a size press for testing by Kumagai Riki Co., Ltd. so that the amount of paper processed becomes 2.48 g / m ^2. After pressing, it was dried at 120 ° C. and 1.0 m / min with a KRK rotary dryer made by Kumagai Riki to obtain a recording paper (9) having a basis weight of 71 g / m ² . FIG. 3 shows the measurement result of the permanent deformation ε in the CD direction using a thermomechanical analyzer (TMA). Table 1 shows the characteristic values of the recording paper.

(Example 10)
The LBKP having a freeness of 380 mL in Example 9 was changed to a medium-quality deinked pulp having a freeness of 380 mL, and from 6 parts by mass of a temperature-sensitive water-soluble titanium compound (T-2762, manufactured by Matsumoto Pharmaceutical Co., Ltd.) Titanium compound 2 (manufactured by Matsumoto Pharmaceutical Co., Ltd., TC-400, Ti- (O-R) ₄ (R is (C ₆ H ₁₄ O ₃ N) ₂ and (C ₃ H ₇ O) ₂ )) 12 mass change in parts, except that the addition amount of the sheet was set to 3.85 g / ^{m 2} in the same manner as in example 9, basis weight was obtained recording paper 74g / ^{m 2} (10). FIG. 3 shows the measurement result of the permanent deformation ε in the CD direction using a thermomechanical analyzer (TMA). Table 1 shows the characteristic values of the recording paper.

(Example 11)
The pulp dispersion liquid was adjusted so that the solid content of pulp was 380 mL and the solid content of pulp was 0.3% by mass. In this pulp dispersion, succinic anhydride (ASA) -containing sizing agent (Nippon NSC Co., Ltd., Fibran-81) 0.3 parts by mass with respect to 100 parts by mass of pulp solids contained in the pulp dispersion And 0.5 parts by mass of cationized starch (NCAT Co., Ltd., Cato-304), and using an 80-mesh wire with an orientation paper machine for experiments made by Kumagai Riki Co., Ltd., making speed 800 m / min. The paper was made under the condition of a paper discharge pressure of 1.5 kg / cm ² . After that, the set was squeezed for 3 minutes at 10 kgf / cm ² with a press for Kumagaya Riki's square sheet machine, and then dried at 120 ° C. and 0.5 m / min on a KRK rotary dryer manufactured by Kumagai Riki. A paper with an amount of 68 g / m ² was obtained. On this paper, as a surface size binder, oxidized starch (manufactured by Oji Cornstarch Co., Ltd., Ace A) 10 parts by weight of bow glass with respect to 100 parts by weight of solid content, 10 parts by weight of surface sizing agent (manufactured by Arakawa Chemical Industries, Ltd., Polymarlon 1355), an 8 mass% aqueous solution (surface size liquid) containing 100 parts by mass of a temperature-sensitive water-soluble titanium compound (manufactured by Matsumoto Pharmaceutical Co., Ltd., T-2762), and heated to 50 ° C. After being size-pressed with a size press for testing manufactured by Kumagai Riki, so that the content of is 0.91 g / m ² , it is dried at 85 ° C. and 1.0 m / min on a KRK rotary dryer manufactured by Kumagai Riki, A recording paper (11) having a basis weight of 70 g / m ² was obtained. FIG. 3 shows the measurement result of the permanent deformation ε in the CD direction using a thermomechanical analyzer (TMA). Table 1 shows the characteristic values of the recording paper.

(Comparative Example 1)
A recording paper having a basis weight of 70 g / m ^{2 in} the same manner as in Example 5 except that the water-soluble titanium compound 1 of Example 5 was changed to polyacrylamide (manufactured by Arakawa Chemical Industries, Ltd., Polymer Set HP-715). R-1) was obtained. FIG. 3 shows the measurement result of the permanent deformation ε in the CD direction using a thermomechanical analyzer (TMA). Table 1 shows the characteristic values of the recording paper.

(Comparative Example 2)
Table 1 shows the characteristic values of the recording paper, using commercially available paper (Green 100 paper manufactured by Fuji Selox Office Supply) as Comparative Example 2. FIG. 3 shows the measurement result of the permanent deformation ε in the CD direction using a thermomechanical analyzer (TMA). Table 1 shows the characteristic values of the recording paper.

(Comparative Example 3)
Recording paper (R-3) having a basis weight of 70 g / m ^{2 in} the same manner as in Example 2 except that the amount of β-1,3-glucan added in Example 2 was changed from 100 parts by mass to 2000 parts by mass. Got. FIG. 3 shows the measurement result of the permanent deformation ε in the CD direction using a thermomechanical analyzer (TMA). Table 1 shows the characteristic values of the recording paper.

(Comparative Example 4)
A recording paper (R-4) having a basis weight of 70 g / m ² was obtained in the same manner as in Example 5 except that the water-soluble titanium compound 1 of Example 5 was changed to chitosan (Daichi Seika's Daichitosan). . FIG. 3 shows the measurement result of the permanent deformation ε in the CD direction using a thermomechanical analyzer (TMA). Table 1 shows the characteristic values of the recording paper.

(Comparative Example 5)
The pulp dispersion liquid was adjusted so that the solid content of pulp was 380 mL and the solid content of pulp was 0.3% by mass. In this pulp dispersion, 0.3 parts by mass of a succinic anhydride (ASA) internal sizing agent (Fibran-81 manufactured by NSC Japan) with respect to 100 parts by mass of pulp solids contained in the pulp dispersion, And 0.5 parts by mass of cationized starch (Cato-304 manufactured by Nippon NSC Co., Ltd.), and using an 80-mesh wire with a laboratory orientation paper machine manufactured by Kumagai Riki, paper making speed of 1600 m / min, paper Paper making was performed under the condition of a material discharge pressure of 1.5 kg / cm ² . After that, the set was squeezed for 3 minutes at 10 kgf / cm ² with a press for Kumagaya Riki's square sheet machine, and then dried at 120 ° C. and 0.5 m / min on a KRK rotary dryer manufactured by Kumagai Riki. A paper with an amount of 68 g / m ² was obtained. On this paper, as a surface size binder, oxidized starch (manufactured by Oji Cornstarch Co., Ltd., Ace A) 10 parts by weight of bow glass with respect to 100 parts by weight of solid content, 10 parts by weight of surface sizing agent (manufactured by Arakawa Chemical Industries, Ltd., Polymeral 1355), an 8% by weight aqueous solution (surface size liquid) containing 10 parts by mass of a temperature-sensitive water-based titanium compound (manufactured by Matsumoto Pharmaceutical Co., Ltd., T-2762) is heated to 50 ° C. Size press with a Kumagaya Riki test size press so that the content is 0.15 g / m ^2, and then dry with a KRK rotary dryer manufactured by Kumagaya Riki under the conditions of 85 ° C. and 1.0 m / min. A recording paper (R-5) having an amount of 70 g / m ² was obtained. FIG. 3 shows the measurement result of the permanent deformation ε in the CD direction using a thermomechanical analyzer (TMA). Table 1 shows the characteristic values of the recording paper.

(Comparative Example 6)
A basis weight of 70 g / m ² was obtained in the same manner as in Example 10 except that the water-soluble titanium compound 2 (manufactured by Matsumoto Pharmaceutical Co., Ltd., TC-400) in Example 10 was changed from 12 parts by mass to 30 parts by mass. Recording paper (R-6) was obtained. Table 1 shows the characteristic values of the recording paper.

(Comparative Example 7)
A recording paper (R-7) having a basis weight of 70 g / m ² was obtained in the same manner as in Example 7 except that the titanium compound in Example 7 was not added. FIG. 3 shows the measurement result of the permanent deformation ε in the CD direction using a thermomechanical analyzer (TMA). Table 1 shows the characteristic values of the recording paper.

<Evaluation method>
(1) Curling evaluation in electrophotographic recording system Each recording paper produced in Examples 1 to 11 and Comparative Examples 1 to 4 was conditioned at 23 ° C. and 65% RH for 12 hours, and felt of the paper. The side surface (FS surface: the surface opposite to the dewatering surface during paper making) was the printing surface, and one-sided copying was performed using DocuPrint 260 manufactured by Fuji Xerox Printing Systems Co., Ltd., and the following evaluation was performed. Printer output was performed without placing an image on a sheet cut into A4 size so that the MD direction (paper making direction) was the longitudinal direction, and the running performance was evaluated according to the following evaluation criteria. FIG. 4 is an explanatory diagram for the measurement of curl after heat fixing, and h indicates the curl height of the recording paper 10 after heat fixing. ◎ and ○ are acceptable levels. The results are shown in Table 2.
A: h <30 mm
○: 30 mm ≦ h <45 mm
Δ: 45 mm ≦ h <60 mm
×: h ≧ 60 mm

(2) Evaluation of paper jam in the copying machine Each recording paper produced in Examples 1 to 11 and Comparative Examples 1 to 4 was conditioned at 23 ° C. and 65% RH for 12 hours, and felt side surface of the paper ( One side copy was performed using DocuCenterColor 500 manufactured by Fuji Xerox Co., Ltd., and the following evaluation was performed. A single color black image with a dot area ratio of 100% is placed on the paper that has been cut into A4 size so that the MD direction (paper making direction) is the longitudinal direction, and 1000 sheets are output and run according to the following evaluation criteria Performance was evaluated. ◎ and ○ are acceptable levels. The results are shown in Table 2.
A: There is no problem in running performance. There is no practical problem.
○: A paper jam occurs in the machine with a probability of 3/1000 or less. There is no practical problem.
Δ: A paper jam occurs in the machine with a probability of 10/1000 or less. There are practical problems.
X: A paper jam occurs in the machine with a probability of 10/1000 or more. There are practical problems.

(3) Toner transferability evaluation Each of the recording sheets prepared in Examples 1 to 11 and Comparative Examples 1 to 4 was conditioned at 23 ° C. and 50% RH for 12 hours or more, and felt side surface of the sheet ( The opposite side of the dewatering surface during paper making was the printing surface, and using A Color 936 made by Fuji Xerox Co., Ltd., a monochrome black image with a dot area ratio of 100% was placed and evaluated as follows: The toner transfer unevenness was evaluated according to the standard. ◎ and ○ are acceptable levels. The results are shown in Table 2.
A: There is no toner transfer unevenness and it is extremely excellent. There is no problem in practical use.
○: Toner transfer unevenness occurs very slightly. There is no problem in practical use.
Δ: Toner transfer unevenness slightly occurred. There are practical problems.
X: Toner transfer unevenness is large and inferior. There are practical problems.

(4) Curling Evaluation after Ink-jet Method Standing Drying Each recording paper produced in Examples 1-11 and Comparative Examples 1-4 was conditioned for 12 hours in an environment of 23 ° C. and 65% RH, and recorded in postcard size. Take 5mm of blank space on the paper, use a Canon Inc. inkjet printer (N2100) to print a 100% black solid image, and leave it on a flat surface in an environment of 23 ° C and 50% RH. Then, the amount of hanging curl generated after leaving for 100 hours after printing was measured. The measured value was converted into a curl curvature and evaluated. The evaluation criteria are as follows, and ◎ and ○ are acceptable levels. The results are shown in Table 2.
◎: Less than 30 m ⁻¹ ○: 30 m ⁻¹ or more and less than 55 m ⁻¹ Δ: 55 m ⁻¹ or more and less than 75 m ⁻¹ ×: 75 m ⁻¹ or more

  As can be seen from Table 2, the recording papers of Examples 1 to 11 in which the CD direction permanent strain ε is in a predetermined range are excellent in curling after fixing, paper jam in the copying machine, transferability, and excellent in electrophotographic characteristics. Excellent ink jet system suitability. On the other hand, the recording papers of Comparative Examples 1 to 4 in which the CD direction permanent strain ε is outside the predetermined range are inferior in electrophotographic system characteristics and ink jet system aptitude.

It is a figure which shows the outline of an example of the thermomechanical analyzer (TMA) used by embodiment of this invention. It is a figure which shows the outline | summary of an example of the measurement result by the thermomechanical analyzer (TMA) in embodiment of this invention. It is a figure which shows CD direction permanent strain (epsilon) in the Example and comparative example of this invention. It is the schematic explaining the measurement of the curl after the heat fixing in the Example of this invention.

Explanation of symbols

1 thermomechanical analyzer, 10 recording paper, 12 tension generator, 14 dimension detector, 16
Heating unit, 18 gripping tool, 20 tension probe, 22 heating / humidification chamber, 24 humidity air supply port, 26 humidity supply device.

Claims (3)

A recording paper characterized in that at least cellulose pulp is used as a raw material, and the permanent deformation ε in the CD direction of the paper represented by the following formula is in the range of 0.001 to 0.050%.
Permanent distortion in CD direction of paper ε (%) = (ΔL / L) × 100
(In the above formula, ΔL is a paper sample having a width of 4 mm and a length of 30 mm, left at 20 ° C. under a tensile stress of 0.0025 N / mm ^{2 in} a 50 ° C./65% RH environment, and then 1 at a rate of 15 N / sec. immediately after applying a tensile stress to .4N / mm ^2, when releasing the tension at a rate of 15N / sec to 0.0025 / mm ² stress, tensile dimension of the sheet sample 3 seconds after applying a maximum value of the stress (L represents the initial size (μm) of the paper sample.) The recording sheet includes a base material, or a base material and a coating layer, and at least one of the base material and the coating layer contains a compound represented by the following structural formula. Item 2. A recording sheet according to item 1.
Ti (OR) _4-n (OR ') _n
(In the above structural formula, R represents a substituent combined with the compound, R ′ represents a polymer chain constituting the recording paper, and n represents an integer of 1 to 4.)   2. The recording sheet according to claim 1, wherein the recording paper includes a base material, or a base material and a coating layer, and at least one of the base material and the coating layer contains a thermosetting material. Recording sheet.

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