JP4432612B2 - Electrophotographic transfer paper and image forming method - Google Patents

Description

  The present invention relates to an electrophotographic transfer sheet having a coating layer used in a copying machine and a printer for forming an image using an indirect dry electrophotographic method, and an image forming method using the same, and particularly, is lightweight. The present invention relates to an electrophotographic transfer sheet and an image forming method using the same.

  In recent years, in the field of on-demand publications, it has become easier to handle small numbers of copies, so it is now possible to use color copiers and color printers for publications that have been produced using commercial offset printing. The tendency to make use of it is prominent. For this reason, color copying machines and color printers are increasing in speed and quality.

As for high image quality, the vividness of the image obtained by using coated paper with high white paper gloss that has been used in the field of commercial printing so far, instead of the PPC paper and printer paper that have been used normally until now. Therefore, cases used for color copying machines and color printers are increasing.
In particular, there is an increasing demand for using light-weight coated paper having an appropriate white gloss for catalogs or booklet text sheets, leaflets, and leaflets that are particularly required to be on-demand.

  However, when such a light-weight coated paper having an appropriate white paper gloss that has been used in the field of commercial printing is used in a full-color copying machine or printer, a phenomenon occurs in which the paper is stretched during fixing. When this phenomenon that the paper is stretched (hereinafter referred to as “paper stretching”) occurs, not only does the problem occur in the registration of the front and back surfaces during double-sided printing, but also when the extreme paper stretching phenomenon occurs, the paper wavy. This causes toner loss during transfer in double-sided printing, paper wrinkles during fixing, and the like, and the commercial value is greatly praised.

  Further, in recent years, with the demand for high speed color copiers and printers, there has been a demand for higher fixing speed. In response to this, the time for fixing the toner on the paper by increasing the pressure contact portion (nip area) between the heating member and the pressure member constituting the fixing device or by increasing the fixing load applied to the paper in the nip area. Means for shortening are adopted. However, when these means are adopted, the deformation force applied to the paper at the time of fixing becomes large, so that the paper elongation phenomenon becomes more and more remarkable. For this reason, the paper elongation at the time of fixing is a very big problem in speeding up color copiers and printers that require on-demand performance.

On the other hand, as a technique for improving the elongation of the coated paper, a proposal has been made that the tear length (tensile strength / basis weight) in the CD direction of the paper is 2.5 km or more (see Patent Document 1).
Further, as a technique for improving paper wrinkles of coated paper, a technique for setting a coefficient of static friction with a fixing rotating body to 4.5 or less has been proposed (see Patent Document 2).
This technique reduces the static friction coefficient between the roll-shaped fixing rotating body (fixing member) and the paper, thereby reducing the static friction coefficient between the portion where the toner image on the paper is transferred and the fixing member, It reduces the static friction coefficient and difference between the blank paper portion and the fixing member, and suppresses deformation of the paper.
JP 2001-83729 A JP 2003-140375 A

However, even if the paper is produced by using the technique for improving the paper elongation and paper wrinkle of the coated paper as described above, a lightweight coated paper having an appropriate white paper gloss, particularly a basis weight of 85 g / m ^2. When the following light-weight coated paper is used in a full-color copying machine or printer that uses an indirect dry electrophotographic method having a high-speed output function, there are cases in which paper elongation or paper wrinkling occurs.
An object of the present invention is to solve the above problems. That is, it is an object of the present invention to provide an electrophotographic transfer paper that is lightweight but does not cause paper expansion and paper wrinkles due to the high-speed fixing device and an image forming method using the same. .

In order to achieve the above-mentioned problems, the present inventors have earnestly investigated why paper elongation and paper wrinkles cannot be suppressed in coated paper using the technology for improving paper elongation and paper wrinkles as described above. investigated.
First, in the technology that suppresses paper elongation by controlling the cutting length, the tensile strength of the coated paper itself decreases as the coated paper becomes lighter even if the tear length is constant. Is thought to be unable to be suppressed. For this reason, especially when a light-weight coated paper is fixed by using a high-speed fixing method in which the recent nip area increases and the deformation of the paper increases, the paper tends to stretch.

A technique for improving the paper wrinkle of coated paper by controlling the coefficient of static friction between the roll-shaped fixing rotating body (fixing member) and the paper is a type of fixing device using a heating roll and a pressure roll. It was made on the premise of.
For this reason, in such a fixing device, it is necessary to increase the nip area by increasing the roll diameter in order to meet the demand for higher speed including energy saving. However, such an increase in the nip area makes it impossible to suppress paper wrinkles because the deformation force applied to the paper during fixing becomes too large. Further, in addition to this, particularly when a light weight paper is used, the paper tends to be stretched.

  Based on the above, the conventional techniques for improving the paper elongation and paper wrinkles of coated paper are not made in consideration of the weight reduction and speedup of coated paper, so these techniques are simply used. This is not enough to meet the need for lighter and faster coated paper.

Based on the above findings, the present inventors have found the following present invention. That is, the present invention
<1>
The base weight which has a pulp fiber as a main component, and the coating layer which has a pigment and an adhesive as a main component on the outermost surface of both surfaces of this base material, and the basic weight measured based on JIS P-8124 is In the electrophotographic transfer paper having a weight of 40 g / m ² or more and 85 g / m ² or less,
An electrophotographic transfer sheet having a surface static friction coefficient of 0.85 or less and satisfying the following formula (1).
Formula (1) 3.5 × 10 ⁵ ≦ t × E
[In the formula (1), t represents the thickness (μm) of the electrophotographic transfer paper, and E represents the tensile modulus (Mpa) in the CD direction of the electrophotographic transfer paper. ]

<2>
The electrophotographic transfer paper according to <1>, wherein the glossiness of the blank paper measured based on JIS P-8142 is 30% or more.

<3>
The electrophotographic transfer paper according to <1> or <2>, wherein the coating layer contains a release agent.

<4>
The electrophotographic transfer according to any one of <1> to <3>, wherein the substrate and / or the coating layer contains a crosslinking agent that undergoes a crosslinking reaction with a hydroxyl group or a carboxyl group. It is paper.

<5>
A latent image forming step of forming a latent image on the latent image carrier; a developing step of developing the latent image using an electrophotographic developer to obtain a toner image; and a transferring step of transferring the toner image to a transfer medium And a fixing step of heat-pressing the toner image on the surface of the transfer body using a fixing device, and forming an image at a constant process speed,
In the image forming method, the transfer target is the electrophotographic transfer paper according to any one of <1> to <4>.

<6>
The fixing device includes a heat fixing member having a heat source, and a pressure member disposed so as to face the surface of the heat fixing member in pressure contact with the heat fixing member,
<5> The surface of the pressure member in pressure contact with the surface of the heat fixing member contains a fluororubber composition, and the ten-point average roughness Rz is in the range of 0.1 to 10 [mu] m. The image forming method described in 1.

<7>
The fixing device press-contacts a heat-fixing member having a heat source, a pressure member including an endless belt disposed so as to press-contact the surface of the heat-fixing member, and an inner peripheral surface of the endless belt. The image forming method according to <5> or <6>, further comprising a pressure applying member that is arranged so as to press the surface of the heat fixing member via the endless belt.

<8>
The image forming method according to any one of <5> to <7>, wherein the process speed is 300 mm / s or more.

  As described above, according to the present invention, an electrophotographic transfer sheet that is lightweight but does not cause sheet expansion and paper wrinkles caused by the sheet even when fixed by a high-speed fixing device, and an image using the transfer sheet. A forming method can be provided.

(Electrophotographic transfer paper)
The electrophotographic transfer paper of the present invention (hereinafter sometimes simply referred to as “coated paper”) includes a base material containing pulp fibers as a main component, a pigment and an adhesive on the outermost surfaces of both sides of the base material. In an electrophotographic transfer paper having a basis weight measured in accordance with JIS P-8124 of 40 g / m ² or more and 85 g / m ² or less, the surface static friction coefficient is 0. .85 or less and satisfies the following expression (1): Expression (1) 3.5 × 10 ⁵ ≦ t × E
In Equation (1), t represents the paper thickness (μm) of the electrophotographic transfer paper, and E represents the tensile modulus (Mpa) in the CD direction of the electrophotographic transfer paper.

  The CD direction refers to a direction perpendicular to the MD (Machine Direction) direction (CD (Cross Direction) when the flow direction of pulp fibers (that is, the paper making direction) is the MD direction in the production of papers as a base material. )) Means the direction specified.

  As a result of repeated studies on the mechanism of occurrence of the phenomenon in which the paper generated at the fixing unit stretches, the present inventors have found that the paper stretch is larger in the coated paper than in the uncoated paper. In the paper, it was recognized that the lower the basis weight, the larger the elongation, and the following generation mechanism was established.

  In other words, it is assumed that a tensile load is applied at the time of fixing as a premise of the occurrence of paper elongation. This tensile load is caused by the fixing device driving force against the paper generated in the nip at the time of fixing and the paper fixing. It is presumed that this occurs due to a contradictory force of deterrence that tries to stay in the nip.

  The magnitude of the driving force is determined by the performance of the fixing device and is considered not to depend greatly on the paper type, but the deterrence is considered to depend on the adhesion between the fixing member and the paper, and this adhesion is large. As a result, the tensile load applied to the paper increases. The reason why the coated paper is larger than the uncoated paper is that the coated paper has better surface properties than the non-coated paper. This is thought to be due to an increase in.

  When the adhesion force is the same, the tensile load applied to the paper is also the same. In this case, the paper having a lower basis weight has a lower strength, and therefore the paper elongation increases. This is the reason why the paper elongation increases with the same brand of coated paper with a low basis weight.

  In view of the above-mentioned situation, the present inventors have intensively studied the characteristics of paper that does not cause paper elongation at the fixing unit, and as a result, regarding the relationship between the fixing member and the paper, the adhesiveness between the fixing member on the pressure side and the paper is It has been found that the fact that the paper itself contributes greatly to the elongation, and the ease of elongation of the paper itself, is obtained by multiplying the tensile elastic modulus of the paper by the paper thickness of the paper as the index indicating the ease of elongation. Only when the static friction coefficient of the paper is kept below a certain value and the value obtained by multiplying the tensile modulus of the paper by the paper thickness of the paper is above a certain value, it is not possible to control the paper elongation until now. As for coated paper, it is possible to obtain a paper whose paper elongation can be controlled, and the present invention has been completed.

Here, the coated paper of the present invention needs to have a static friction coefficient of 0.85 or less on its surface, preferably 0.70 or less, and more preferably 0.60 or less.
When the coefficient of static friction exceeds 0.85, the adhesion between the sheet and the pressure member surface of the fixing device becomes too large, the tensile load applied to the sheet increases, and the sheet stretches greatly.
If the coefficient of static friction is 0.85 or less, the tensile load applied to the paper does not become too large, but if it is less than 0.05, the paper may be displaced within the nip. For this reason, it is preferable that a static friction coefficient is 0.05 or more, and it is more preferable that it is 0.1 or more.

The static friction coefficient of the coated paper surface of the present invention is a sheet containing a fluororubber composition whose constituent material and surface roughness are similar to the surface of a typical pressure member used in a fixing device (fluororubber ( Polyol vulcanization type G-702 (manufactured by Daikin Industries, Ltd.) 95 parts by mass, magnesium oxide (Kyowa Chemical Industry Co., Ltd.) 5 parts by mass, and fluororesin fine particles (Lublon L-5F, Daikin Industries, Ltd.) 30 parts by mass A rubber composition prepared by mixing with a polyimide sheet is coated on a polyimide sheet to a thickness of 200 μm, baked at 230 ° C. for 3 hours, and prepared with sandpaper so that the ten-point average roughness Rz of the sheet surface is 3 μm. The sheet was measured with a surface static friction measuring instrument HEIDON manufactured by Shinto Kagaku Co., Ltd. as a measuring instrument.
In the measurement, a sheet containing a fluororubber composition is fixed, the sheet is brought into surface contact with the surface and a load of 150 g is applied (width 30 mm, NIP width 1.9 mm), and the sheet is moved at a speed of 5 mm / sec. And by sliding the sheet surface.
The ten-point average roughness Rz of the sheet surface was measured using a surface roughness measuring instrument (model number: 575A) manufactured by Tokyo Seimitsu Co., Ltd. Measured by moving 2.5 mm at 0.03 mm / sec. At this time, the measurement magnification was set to horizontal direction × 50 and vertical direction × 5000.

Further, the coated paper of the present invention needs to have a value of t × E of 3.5 × 10 ⁵ or more and 3.7 × 10 ⁵ or more as shown in the formula (1). Is preferably 4.0 × 10 ⁵ or more.
If the value of t × E is less than 3.5 × 10 ⁵ , the paper cannot counter the tensile load generated in the nip, and paper elongation occurs. Further, the larger the value of t × E, the lower the sheet elongation can be suppressed. However, if the value becomes too large, the rigidity of the sheet or the sheet thickness becomes too large, and the booklet after the image output / bookbinding process becomes too large. It causes adverse effects such as difficulty in turning. In consideration of the ease of turning the booklet, the value of t × E is preferably 9.0 × 10 ⁵ or less, and more preferably 8.0 × 10 ⁵ or less.

Further, the coated paper of the present invention preferably has a blank paper glossiness of 30% or more, preferably 40% or more, and more preferably 50% or more, measured based on JIS P-8142. . If the glossiness of the blank paper does not reach 30%, the image obtained after output may lack clarity.
On the other hand, it is preferable that the blank paper glossiness is closer to 100% because the clearness of the image is obtained, but the higher the blank paper glossiness, the higher the smoothness. For this reason, when an image is formed using the coated paper of the present invention, the adsorptive power of the coated paper to the fixing member surface increases depending on the adhesiveness and surface roughness of the fixing member surface of the image forming apparatus to be used. In some cases, the paper may be stretched. For this reason, the upper limit of the glossiness of the blank paper is preferably set to 80% or less when consideration should be given to use under conditions where the adhesive force of the coated paper to the fixing member surface may increase.

As a method for reducing the coefficient of static friction on the coated paper surface, there is a method for reducing the contact area between the surface of the pressure member and the coated paper surface at the time of fixing. Here, generally, in order to reduce the static friction coefficient, the direction of improving (smoothing) the surface property of the coated paper is generally used.
However, in order to control the static friction coefficient of the coated paper surface from the viewpoint of suppressing the paper elongation, the present inventors do not directly try to control the frictional force itself between the coated paper surface and the pressure member surface. We thought it important to control the adhesion between these two surfaces.
Here, as a method of controlling the adhesive force between the coated paper surface and the pressure member surface, [1] a method of reducing the surface energy of the coated paper surface by blending a release agent in the coated layer And [2] a method of reducing the contact area when the pressure member surface and the coated paper surface come into contact with each other.

  Examples of mold release agents incorporated in the coating layer include waxes, higher fatty acids, higher fatty acid metal salts, higher fatty acid esters, higher fatty acid amides, higher fatty alcohols, silicon compounds and fluorine compounds. Etc. These release agent compounds may be used alone or as a mixture of two or more thereof.

  Examples of waxes include synthetic and natural waxes such as paraffin wax, chlorinated paraffin wax, microcrystalline wax, polyethylene wax, ceresin wax, montan wax, carnauba wax, candelilla wax, wood wax and beeswax.

Examples of higher fatty acids include stearic acid, oleic acid, palmitic acid, lauric acid, myristic acid, sebacic acid and the like. Examples of higher fatty acid metal salts used in the present invention include salts of higher fatty acids such as Ba, Ca, Zn, Al, and Mg.
Examples of the higher fatty acid ester include esters of the above higher fatty acid and alcohols, and esters of the above higher fatty acid and glycols. Examples of higher fatty acid amides include the above fatty acids and amides such as ammonia, alkyl amines, or alkylene diamines. Specific examples include stearic acid amide, palmitic acid amide, methylene bisstearyl amide, and ethylene bisstearyl amide. Etc. can be used.

Examples of the higher alcohol include lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, and behenyl alcohol.
Silicon compounds include liquid, semi-solid or solid silicone compounds. Specifically, the main chain has a siloxane bond as a basic structure, and the side chain has a methyl group, a phenyl group, a vinyl group. And silicone rubber compounds having an organic substituent such as a group.
Such a silicone compound may further have a carboxyl group, an amino group, a quaternized amino group, a fluorine atom, or the like as a substituent, and may be a polymer having a three-dimensional network structure.

  As the fluorine compound, a liquid, semi-solid or solid fluorocarbon compound can be used. Specifically, fluorine-containing polymers such as tetrafluoroethylene, polychlorotrifluoroethylene, and polyvinylidene fluoride, and fluorine-substituted compounds. Examples thereof include hydrocarbons having a long-chain alkyl group, alcohols, carboxylic acids, sulfonic acids, sulfonates, and sulfonamides.

The mold release agents listed above can be added to the coating solution as it is and used for forming the coating layer when used, but a solution in which this is dissolved in an organic solvent or water, or water as a medium. It can also be used in the form of an emulsion or suspension.
The amount of the release agent added is preferably in the range of 0.01 to 10 parts by mass with respect to 100 parts by mass of the pigment component used for forming the coating layer. When the addition amount of the release agent is less than 0.01 parts by mass, the coefficient of static friction of the coated paper is not sufficiently reduced, and thus the paper elongation may not be suppressed low.
On the other hand, if the addition amount of the release agent exceeds 10 parts by mass, the release agent intervenes between the coated paper surface and the toner image transferred to the surface, The toner image to be fixed has a portion that cannot be fixed, so that an accurate image cannot be fixed. In addition, the release agent bleed out from the coating layer adheres to the surface of the transport roll in the apparatus, and jams (paper jams). ) May be caused.

A specific method for reducing the contact area between the pressure member surface and the coated paper surface is a method of adjusting the particle size of the pigment contained in the coating layer.
Usually, the pigment contained in the coating layer is a known pigment such as kaolin or calcium carbonate having an average particle size of 1 to 2 μm. In the present invention, at least one pigment contained in the coating layer is used. The average particle size of is preferably 2 μm or more, and more preferably 3 μm or more. When the average particle diameter of the pigment is less than 2 μm, the contact area between the pressure member surface and the coated paper surface may increase, resulting in the occurrence of paper elongation.

  In order to reduce the contact area between the pressure member surface and the coated paper surface and suppress the occurrence of paper elongation, it is preferable to add a pigment having a large average particle diameter to the coating layer. If the diameter is too large, pigments with large particle diameters are difficult to orient even after smoothing after coating, and the surface roughness of the coated paper tends to increase, reducing the glossiness of blank paper. It is easy to invite. For this reason, the average particle diameter of the large pigment blended in the coating layer for the purpose of reducing the contact area is preferably 6 μm or less, and more preferably 4 μm or less.

Moreover, it is preferable to mix | blend 5 mass parts or more with respect to 100 mass parts of all the pigments with which such an average particle diameter is 2 micrometers or more, and mix | blends 7 mass parts or more. It is more preferable. When the blending ratio is less than 5 parts by mass, the contact area between the pressure member surface and the coated paper surface may increase, resulting in the occurrence of paper elongation.
In order to reduce the contact area between the pressure member surface and the coated paper surface and suppress the occurrence of paper elongation, it is preferable to blend a pigment with a diameter as large as possible into the coating layer, but the blending ratio When the amount is too large, the surface roughness of the coated paper tends to increase, which tends to cause a decrease in the glossiness of the white paper. For this reason, the large-diameter pigment blended in the coating layer for the purpose of reducing the contact area is preferably 25 parts by mass or less with respect to 100 parts by mass of the total pigment blended in the coating layer. It is more preferable that the amount is not more than part by mass.

In addition, as a specific method for reducing the contact area between the pressure member surface and the coated paper surface, an adhesive having a large shrinkage rate during drying, for example, starches or PVA (polyvinyl alcohol) which are water-soluble binders. The blending amount may be 5 parts by mass or more, preferably 7 parts by mass or more with respect to 100 parts by mass of the total pigment blended in the coating layer.
When such an adhesive having a large shrinkage is blended, when the coating layer forming solution is applied to the substrate surface, the pigment itself is oriented so that the surface roughness of the coated paper is as small as possible. As the adhesive shrinks in the drying step, the pigment orientation is also greatly disturbed, so that the contact area between the pressure member surface and the coated paper surface can be reduced. When the blending ratio is too small, the pigment itself is oriented so that the surface roughness of the coated paper is as small as possible, so it is difficult to reduce the contact area between the pressure member surface and the coated paper surface. There is a case.
The upper limit of the blending ratio of the adhesive having a large shrinkage ratio during drying is not particularly limited, but can be appropriately adjusted according to the average particle diameter and blending ratio of the large diameter pigment to be used.

In addition, as a method of controlling the value of t × E shown in Equation (1), when roughly classified, a method of increasing the tensile elastic modulus E in the CD direction of the coated paper and a paper thickness t of the coated paper are increased. Two methods are mentioned.
First, as a method for increasing the tensile elastic modulus E, a method in which a crosslinking agent that undergoes a crosslinking reaction with a hydroxyl group or a carboxyl group is contained in the substrate and / or the coating layer can be mentioned.

When such a cross-linking agent is contained in the base material, it causes a cross-linking reaction with hydroxyl groups contained in a large amount of cellulose constituting the pulp fiber in the base material and carboxyl groups that may be present in a small amount, and between the fibers. The tensile elastic modulus E can be improved by firmly bonding.
In addition, a crosslinking reaction with starches, caseins, polyvinyl alcohols, or carboxymethylcelluloses, which are water-soluble polymer binders contained as an adhesive in the coating layer, by incorporating a crosslinking agent in the coating layer The tensile elastic modulus E can be improved by bonding the binder more firmly.

  Examples of the crosslinking agent capable of crosslinking with a hydroxyl group or a carboxyl group present in pulp fiber or a water-soluble polymer binder include, for example, an isocyanate crosslinking agent, a melamine crosslinking agent, an epoxy crosslinking agent, and a carbodiimide crosslinking agent. A zirconium carbonate-based crosslinking agent or the like can be used, but is not limited thereto.

  In addition to the means for adding a crosslinking agent to the base material and the coating layer, the method for improving the tensile modulus E is as follows: [1] Advance the beating degree of the pulp used to make the base material to increase the freeness. Reduce to 300 cc or less, [2] Add a wet paper strength enhancer such as polyacrylamide, polyamide, polyamide / epichlorohydrin resin or dry paper strength enhancer to the pulp slurry, 0.8 mass% or more per pulp, [3] Polymerization [4] Coating layer containing polyvinyl alcohol having a degree of 1000 or more, carboxymethylcellulose, or starch having a relatively high molecular weight (weight average molecular weight of 100,000 or more) in the substrate by a method such as internal addition or size press. A synthetic adhesive having a glass transition temperature of 30 ° C. or higher, and [5] polyvinyl alcohol having a polymerization degree of 1000 or higher, Le cellulose, or a method can be mentioned to contain relatively high molecular weight starch (weight average molecular weight of 100,000 or more) coated layer.

  Moreover, as a method of increasing the paper thickness t, there is a method in which a binding inhibitor that inhibits binding between pulp fibers is contained in the base material. The binding inhibitor used in the present invention has a function of inhibiting the binding between pulp fibers contained in the base material and increasing the binding distance between pulp fibers, and the binding between pulp fibers. Increasing the distance has the effect of increasing the overall thickness of the paper.

The binding inhibitor used in the present invention is not particularly limited as long as it is a drug having the above-described function. Specifically, it is called a so-called low density agent, bulking agent, softening agent, and the like. Drugs can be used.
For example, an anionic surfactant, a cationic surfactant, a zwitterionic surfactant, and a nonionic surfactant are adsorbed on the pulp fiber as the density reducing agent or bulking agent. For example, those having a hydrophilic group in the molecule and a hydrophobic group that inhibits the formation of hydrogen bonds in water molecules or pulp fibers.
As such surfactants, KB-08W (nonionic surfactant) manufactured by Kao Corporation or KB-115 (nonionic surfactant) manufactured by Toho Chemical Industry Co., Ltd. -500 (anionic surfactant), PEA-100 (cationic surfactant) manufactured by Nissin Chemical Laboratory, PEA-200 (nonionic surfactant), PEA-300 (cationic interface) Activator), Prosoft 230 (cationic surfactant) manufactured by Riken Green Co., Ltd., Prosoft 1003 (cationic surfactant), and the like.

Furthermore, as the softening agent, various softening agents used for paper media that require flexibility such as toilet paper and tissue paper can be used.
Specific examples of such softeners include, for example, the surfactants listed above, wax emulsions such as polyethylene wax, silicone compounds such as dimethylpolysiloxane, cation-modified silicone, and epoxy-modified silicone, and urethane-based high polymers. Examples include, but are not limited to, molecules, glycerin, fatty acid esters, paraffin emulsions, quaternary ammonium salts, isopropyl alcohol, urea, polyethylene glycol, fatty acid polyamide polyamines, polyhydric alcohols, and the like. .

In order to satisfy the desired thickness and strength of the coated paper, the value of t × E shown in the formula (1) is in the range of 3.5 × 10 ⁵ or more, and the above-mentioned crosslinking agent and binding inhibition. The type and amount of the agent can be selected as appropriate according to the specifications of the required paper thickness and paper strength.

Further, coated paper having a basis weight of the present invention needs to be ^{40g / m 2 ~85g / m 2} , preferably in the range of ^{45g / m 2 ~85g / m 2} , 45g More preferably, it is in the range of / m ^{2 to} 73 g / m ² .
When the basis weight of the paper is less than 40 g / m ² , the basis weight is too small, so that a sufficient paper thickness or tensile elastic modulus cannot be obtained, and the paper elongation cannot be controlled. On the other hand, when it exceeds 85 g / m ² , the specifications originally required for lightweight and thin coated paper such as text paper cannot be sufficiently satisfied, and the application range of products is remarkably narrowed.

The coated paper of the present invention preferably has a paper density of 1.00 g / cm ³ or more. When the paper density is less than 1.00 g / cm ³ , when a large number of coated papers are overlapped at the time of bookbinding or the like, the paper may be bulky and the storage property may be reduced.
A more preferable paper density is 1.05 g / cm ³ or more, and a more preferable paper density is 1.10 g / cm ³ or more.

  The pulp fiber used for the substrate in the present invention is not particularly limited, but pulp fibers used for the base paper of ordinary general coated paper, for example, kraft pulp fiber, sulfite pulp fiber, semi-solid It is preferable to use chemical pulp fibers, chemiground pulp fibers, groundwood pulp fibers, refiner ground pulp fibers, thermomechanical pulp fibers, etc. in consideration of price. Moreover, the fiber which chemically modified the cellulose or hemicellulose in these fibers can also be used as needed.

Furthermore, cotton pulp fiber, hemp pulp fiber, kenaf pulp fiber, viscose rayon fiber, copper ammonia rayon fiber, cellulose acetate fiber, polyvinyl chloride fiber, polyacrylonitrile fiber, polyvinyl alcohol fiber, polyvinylidene chloride fiber, polyolefin Fiber, polyurethane fiber, polyvinyl chloride, polyvinyl alcohol copolymer, fluorocarbon fiber, glass fiber, carbon fiber, alumina fiber, metal fiber, silicon carbide fiber and the like can be used alone or in combination. If necessary, fibers obtained by impregnating or thermally fusing pulp fibers with a synthetic resin such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, or polyester can also be used.
Furthermore, considering environmental problems in recent years, it is desirable to add high-quality and medium-quality waste paper pulp, and its blending amount is determined according to the use, but it is preferably 10% by mass or more based on the total pulp fiber, preferably It is 30% by mass or more, more preferably 50% by mass or more.

  In addition, a filler can be used for the base material constituting the coated paper of the present invention in order to improve the coating suitability and to adjust the opacity and whiteness after coating. Fillers that can be used here include heavy calcium carbonate, light calcium carbonate, kaolin, calcined clay, pyroferrite, sericite, talc, and other inorganic fillers such as silicic acid and titanium dioxide, and urea resin, styrene, etc. Organic pigments can be mentioned, but are not limited to these. Although the compounding quantity of these fillers is not specifically limited, It is 1-20 mass% with respect to the total solid of a pulp slurry, More preferably, it uses in the range of about 3-15 mass%.

  Various chemicals such as a sizing agent used for the substrate constituting the coated paper of the present invention can be used by internal or external addition. Types of sizing agents can include sizing agents such as rosin sizing agents, synthetic sizing agents, petroleum resin sizing agents, and neutral sizing agents. Suitable sizing agents such as sulfate bands and cationized starch, fibers Can be used in combination with other fixing agents. From the viewpoint of paper storage stability after copying in electrophotographic copying machines, printers, etc., neutral sizing agents such as alkenyl succinic anhydride sizing agents, alkyl ketene dimers, alkenyl ketene dimers, neutral rosins, petroleum sizes, Olefin resins and styrene / acrylic resins are preferred.

  Furthermore, in addition to the above-mentioned electron conductive materials for the purpose of adjusting the electrical resistance value of the coated paper, inorganic substances such as sodium chloride, potassium chloride, calcium chloride, sodium sulfate, alkyl phosphate ester acid, alkyl sulfate ester Organic materials such as acid, sulfonic acid sodium salt and quaternary ammonium salt can be used alone or in combination.

In addition, a paper strength enhancer can be internally or externally added to the substrate as required. Paper strength enhancers include starch, modified starch, vegetable gum, carboxymethylcellulose, polyvinyl alcohol, polyacrylamide, urea-formaldehyde resin, melamine-formaldehyde resin, dialdehyde starch, polyethyleneimine, epoxidized polyamide, polyamide / epichlorohydrin resin , Methylolated polyamide, chitosan derivatives and the like, and these materials can be used alone or in combination.
In addition to these, various auxiliary agents such as dyes, pH adjusters and the like blended in ordinary coated paper base papers are appropriately used.

In addition, the coated paper of the present invention has the same texture as that of the conventional coated paper and reduces the manufacturing cost. Further, from the viewpoint that the obtained image is clear, the outermost surfaces of both surfaces of the substrate In addition, it is necessary that a coating layer containing a pigment and an adhesive as main components is formed.

  Examples of the pigment used in the coating layer of the coated paper of the present invention include pigments used in ordinary general coated paper, such as heavy calcium carbonate, light calcium carbonate, titanium dioxide, aluminum hydroxide, satin white, talc. , Calcium sulfate, barium sulfate, zinc oxide, magnesium oxide, magnesium carbonate, amorphous silica, colloidal silica, white carbon, kaolin, calcined kaolin, delaminated clay, aluminosilicate, sericite, bentonite, smectite, etc. Pigment pigments, polystyrene resin fine particles, urea formaldehyde resin fine particles, fine hollow particles, and other organic pigments can be used alone or in combination.

As the adhesive used for the coating layer of the coated paper of the present invention, a synthetic adhesive or a natural adhesive can be used.
Synthetic adhesives include styrene / butadiene, styrene / acrylic, ethylene / vinyl acetate, butadiene / methyl methacrylate, vinyl acetate / butyl acrylate, and other copolymers, polyvinyl alcohol, maleic anhydride copolymer, Examples thereof include acrylic acid / methyl methacrylate copolymer. Among these synthetic adhesives, one or more types can be used depending on the purpose. These adhesives are preferably used in the range of 5 to 50% by mass, more preferably about 10 to 30% by mass per 100% by mass of the pigment.
Examples of natural adhesives include generally known adhesives such as oxidized starch, esterified starch, enzyme-modified starch, cold water soluble starch obtained by flash drying them, casein, and soy protein. These adhesives are also used in the range of about 0.1 to 50% by mass, more preferably about 2 to 30% by mass per 100% by mass of the pigment.
Moreover, various auxiliary | assistant mix | blended with the pigment for normal coated papers, such as a dispersing agent, a thickener, a water retention agent, an antifoamer, and a water resistance agent, are used suitably as needed.

The coating layer is formed by applying a coating composition containing the above-described components such as a pigment and an adhesive to the surface of the substrate and drying it.
Here, the coating composition on the substrate surface is a coating apparatus used for general coated paper production, such as a blade coater, air knife coater, roll coater, reverse roll coater, bar coater, curtain coater, A die slot coater, a gravure coater or the like can be used on-machine or off-machine. At the time of coating, the coating composition can be applied to the substrate once or twice or more, and the coating amount is about ² to 15 g / m ^{2 on} one side of the substrate in dry weight. It is preferable to apply so that it becomes.

For smoothing after coating, a commonly used smoothing device such as a super calender, machine calender, soft nip calender, etc. is used, and the density is 1.00 g / cm ³ or more and the white paper gloss is 30% or more. Finished like so.

In addition, the coated paper of the present invention produced under the above conditions is usually moisture-proof wrapping paper such as polyethylene laminated paper and polypropylene so that moisture absorption and desorption does not occur during storage until reaching the consumer's hand. Etc.
In this case, a paper machine or a coater dryer is used so that the moisture content of the coated paper immediately after opening after breaking the packaging is preferably 3 to 6.5%, more preferably 4.5 to 5.5%. It is preferable that the adjustment is performed by a calendar process or the like.

(Image forming method)
The image forming method of the present invention is not particularly limited as long as an image is formed on the electrophotographic transfer paper of the present invention by a known electrophotographic image forming method.
The process of the image forming method of the present invention specifically includes a latent image forming step of forming a latent image on a latent image carrier, and developing the latent image with an electrophotographic developer to form a toner image. A development step for obtaining the toner image, a transfer step for transferring the toner image to a transfer target body (the coated paper of the present invention), and a fixing step for thermocompression-bonding the toner image to the transfer member surface using a fixing device. It is preferable that the image is formed at a constant process speed.

  In addition, other steps may be included as necessary. For example, when transferring a toner image formed on a photosensitive member (latent image carrier) to a transfer target, An intermediate transfer step for transferring the toner image via the intermediate transfer member may be provided. In this case, a color toner image can be formed by superimposing the toner images of the respective colors on the intermediate transfer member, and the color toner image can be transferred onto the transfer member in a lump and then heated and melted to be fixed.

The fixing device includes at least a heat fixing member having a heat source and a pressure member disposed so as to face the surface of the heat fixing member in pressure contact with the heat fixing member.
Here, the pressure member preferably has a fluororubber composition on the surface in pressure contact with the surface of the heat fixing member, and the ten-point average roughness Rz is in the range of 0.1 to 10 μm. preferable. The ten-point average roughness Rz means a value obtained by measurement under the same conditions as the sheet containing the fluororubber composition used for measurement of the static friction coefficient.

  When the fluororubber composition is not used as the material constituting the surface of the pressure member, the pressure member surface has a high adhesive force, and therefore the pressure member surface and the coated paper surface of the present invention are fixed during fixing. In some cases, the frictional force at the time of contact increases, and as a result, the paper stretches.

  In addition, when the ten-point average roughness Rz of the pressure member surface is less than 0.1 μm, the pressure member surface is too smooth and stickiness due to the surface shape is generated. The frictional force at the time of contact with the coated paper surface of the invention increases, and as a result, paper elongation may occur. On the other hand, if the ten-point average roughness Rz exceeds 10 μm, the glossiness of the image surface of the coated paper that contacts the pressure member surface during double-sided printing may decrease.

In the case where the pressure member constituting the fixing device is an endless belt, a pressure applying member that presses the surface of the heat fixing member via the endless belt is disposed so as to press the inner peripheral surface of the endless belt. It is preferable to provide it.
In this case, in order to reduce the sliding resistance between the endless belt and the pressure applying member arranged so as to be in pressure contact with the inner peripheral surface of the endless belt, the surface that contacts the inner peripheral surface of the endless belt of the pressure applying member is covered. Thus, a sheet-like member can be provided.

Further, since the image forming method of the present invention uses the coated paper of the present invention that is lightweight and has an appropriate white paper gloss, it can sufficiently cope with high-speed image formation.
That is, if the image forming method of the present invention is used, the occurrence of paper elongation can be suppressed even when forming an image in a high-speed region with a process speed of 300 mm / s or higher, and even when forming an image in a higher-speed region with 350 mm / s or higher. Therefore, it is possible to cope with a practical upper limit process speed of about 400 mm / s without any problem.

Next, an example of an image forming apparatus used in the image forming method of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram showing an example of an image forming apparatus preferably used in the image forming method of the present invention. The image forming apparatus shown in FIG. 1 includes a photoconductor (latent image carrier) 11. Around the photoconductor 11, a roller charger 12, an exposure device 13, cyan, magenta, yellow, The developing device 14 including the developing devices 14a, 14b, 14c, and 14d loaded with the black developer, the belt-like intermediate transfer member 15, the cleaner 16, and the light neutralizer 17 are arranged in this order. .
The intermediate transfer member 15 is stretched around support shaft rollers 18a, 18b, and 18c. The support roller 18a is in pressure contact with the photosensitive member 11 via the intermediate transfer member 15 and constitutes a primary transfer portion. The support roller 18c is in pressure contact with the transfer roller 19 via the intermediate transfer member 15 to form a secondary transfer unit.

  Further, the contact portion between the transfer roller 19 and the intermediate transfer member 15 is conveyed by a conveying means (not shown) from the paper feeding side indicated by symbol A in the drawing to the paper discharging side indicated by symbol B. The transferred object 20 can be inserted. Further, a heat fixing device mainly composed of a heating roller 1 and a pressure belt 2 is provided on the paper discharge side of the secondary transfer unit, and the transfer target passed through the contact portion of the secondary transfer unit. However, it can pass through the contact portion between the heating roller 1 and the pressure belt 2 in the paper discharge direction.

  Image formation using the image forming apparatus shown in FIG. 1 is performed as follows. First, the photosensitive member 11 charged by the charger 12 is exposed by the exposure device 13 based on each image information of cyan, magenta, and yellow to form a latent image on the photosensitive member 11. The latent image on the photoconductor 11 is developed by developing devices 14a, 14b, 14c, and 14d built in the developing device 14 to form toner images. The developed toner image is transferred onto the belt-like intermediate transfer member 15.

The toner image on the intermediate transfer member 15 moves to the contact portion between the intermediate transfer member 15 and the transfer roller 19 as the intermediate transfer member 15 advances in the direction of arrow P. When the toner image on the intermediate transfer member 15 passes through the contact portion between the intermediate transfer member 15 and the transfer roller 19, the toner image is transferred onto the transfer target 20 inserted through the contact portion. The toner image transferred onto the transfer target 20 is fixed on the transfer target 20 by passing the transfer target 20 between the heating roller 1 and the pressure belt 2 to form an image.
The toner image remaining on the photoconductor 11 after the toner image on the photoconductor 11 is transferred to the transfer target 20 is removed by the cleaner 16, and the residual charge remaining on the photoconductor 11 is removed by the photocharger 17. The charge is removed, and the next image formation is prepared.

  As the fixing device used in the image forming method of the present invention, a contact-type heat fixing device can be used. For example, a heating roller having a rubber elastic layer on a cored bar and, if necessary, a fixing member surface layer, a core A heat roller fixing device comprising a pressure roller having a rubber elastic layer on gold and optionally having a fixing member surface layer, a combination of the roller and the roller, a combination of the roller and the belt, a belt, A fixing device in place of the combination with the belt can be used.

Details of the heat fixing device of the image forming apparatus shown in FIG. 1 will be described with reference to FIG. The thermocompression bonding apparatus shown in FIG. 2 is an apparatus in which a fixing member has a roller shape, and is mainly composed of a heat roller 1 and a pressure belt 2 disposed so as to be in pressure contact therewith.
The heat roller 1 includes a heat source 3, a base material (core) 4, an elastic layer 5, and a fixing member surface layer 6. The heat source 3 is disposed inside the base material 4, and the outer peripheral side of the base material 4. The elastic layer 5 and the fixing member surface layer 6 having a single layer or a laminated structure are sequentially laminated.
When the transfer target 20 on which the toner image 7 is formed passes between the pressure belt 2 and the heat roller 1, it is heated and pressed to fix the image.

  The thermocompression bonding apparatus shown in FIG. 2 further includes a cleaning member for removing toner adhering to the surface of the heat roller 1, a nail (finger) for peeling the recording material from the heat roller 1, and a release agent as necessary. There may be provided a release agent supply device for supplying the heat to the heat roller. The heating source 3 in the thermocompression bonding apparatus shown in FIG. 2 is controlled by a temperature control apparatus (not shown).

As thickness of the elastic layer 5 of the heat roller 1, 0.1-3 mm is preferable and 0.5-2 mm is more preferable. The elastic layer 5 is made of heat-resistant rubber such as silicone rubber or fluorine rubber, and the rubber hardness is preferably 60 or less.
The fixing member having the elastic layer 5 is advantageous in that the fixing member is deformed following the unevenness of the toner image 7 on the transfer target 20, and the smoothness of the image surface after fixing can be improved. is there.
If the thickness of the elastic layer exceeds 3 mm, the heat capacity of the fixing member increases, and it takes a long time to heat the fixing member to a desired temperature. Absent. If the thickness of the elastic layer is less than 0.1 mm and is too thin, the deformation of the fixing member will not be able to follow the unevenness of the toner image, resulting in uneven melting, and the elastic layer effective for peeling cannot be obtained. It is not preferable in terms.

The heat roller 1 is driven to rotate at a predetermined speed along the arrow direction by a drive source (not shown). The heat roller 1 includes a metal core 4 formed in a cylindrical shape, and the metal core 4 is made of, for example, aluminum or stainless steel. The surface of the metal core 4 is covered with an elastic body layer 5, and the surface of the elastic body layer 5 is further dip coated with fluoro rubber as a fixing member surface layer 6. The surface of the surface layer 6 is finished in a state close to a mirror surface state.
The metal core 4 may be made of a metal having a high thermal conductivity, a high strength against deformation, and a good thermal conductivity, in addition to aluminum and stainless steel. As the layer 6, other materials can be used as long as they are elastic bodies with high heat resistance.

  Further, an endless belt-like pressure belt 2 having heat resistance is disposed on the surface of the heat roller 1 so as to be in pressure contact over a predetermined nip width. This pressure belt 2 has a polyimide film or a stainless steel belt as a base material, and the polyimide film surface has a fluororesin such as polytetrafluoroethylene (PTFE), a copolymer of tetrafluoroethylene and perfluoroethylene (PFA), Silicone rubber, fluorine rubber, or the like is coated, and is stretched by three rolls 9, 10, and 11 with a tension of about 5 kgf.

  For example, the diameters of the three rolls 9, 10, and 11 are set to 23 mm, 18 mm, and 18 mm, respectively. Of the three rolls 9, 10, 11, the pressure roll 11 and the inlet roll 9 are formed in a crown shape by, for example, stainless steel, and the steering roll 10 has a silicon rubber coat on the surface. It is formed into a cylindrical or columnar member by applied stainless steel or the like.

  The pressure roll 11 is disposed so as to come into pressure contact with the surface of the heat roll 1 at a pressure of 60 kgf, for example, at the exit (discharge side) of the contact portion between the heat roll 1 and the pressure belt 2. Note that the pressure belt 2 is configured to be driven and rotated while being in pressure contact with the heat roller 1. For this reason, the elastic body layer 5 of the heat roller 1 is deformed, the surface thereof is distorted, and the transferred body 20 can be peeled off due to its own rigidity.

Further, a pad member 12 as a pressure applying member for pressing the pressure belt 2 against the surface of the heat roller 1 with a predetermined pressure is disposed between the roll 9 and the roll 11. The pad member 12 has an elastic layer laminated on a support plate made of a metal such as stainless steel through a shim made of a synthetic resin such as polyphenylene sulfide (PPS) on the surface of a base plate made of a metal such as stainless steel. It is arranged and configured.
The entire surface of the pad member 12 is covered with a pad sheet as a sheet-like member. Furthermore, the pad member 12 is pressed against the heat roller 1 with a pressing force of 50 kgf (490.3 N), for example, by a compression coil spring (not shown) arranged.

  The fixing member may contain various additives depending on the purpose. For example, the fixing member contains carbon black, metal oxide, ceramic particles such as SiC, etc. for the purpose of improving wear resistance and controlling resistance. May be.

The toner and developer used in the image forming method of the present invention are not particularly limited, but the following toner can be preferably used.
Generally, polyester resin or styrene-acrylic resin is mainly used as the resin component of the toner.

As for the method for producing the toner, any production method such as a pulverization method or a polymerization method may be used. A resin particle dispersion in which resin particles are dispersed and a colorant dispersion in which a colorant is dispersed are mixed to obtain a resin. A method is preferred in which the particles and the colorant are aggregated to a toner particle size, and the resulting aggregate is heated and fused to a temperature above the glass transition point of the resin.
The toner preferably has a toner shape factor (SF1) represented by the following formula (2) in the range of 100 to 140.

Formula (2) SF1 = (ML ² × π / 4A) × 100
In the formula, ML represents the maximum toner length, and A represents the projected area of the toner.

  When the shape factor SF1 exceeds 140, the toner fluidity deteriorates and the transferability from the initial stage is affected. Here, the average value of the toner shape factor SF1 can be calculated as follows, for example. That is, with respect to the toner scattered on the slide glass, the optical micrograph is taken into a Luzex image analyzer through a video camera, and the toner shape factor SF1 of 100 or more toners is calculated to obtain an average value.

  In the present invention, the volume average particle diameter of the toner is preferably in the range of 2 to 8 μm, and more preferably in the range of 3 to 7 μm. When the volume average particle diameter of the toner is less than 2 μm, the chargeability tends to be insufficient and the developability may be deteriorated. On the other hand, when it exceeds 7 μm, the resolution of the image may be deteriorated. Therefore, it is not preferable respectively.

  Here, the volume average particle diameter of the toner means a particle diameter at which the cumulative volume becomes 50% from the small diameter side. For example, Coulter Counter TA-II (manufactured by Nikka Kisha Co., Ltd.), Multisizer II (manufactured by Nikka Kisha Co., Ltd.). ) Or the like.

  The particle size distribution of the toner is preferably such that the volume average particle size distribution GSDv is 1.28 or less, more preferably 1.25 or less. A sharp toner can be obtained. If GSDv exceeds 1.28, the sharpness and resolution of the image are lowered, which is not preferable.

Here, the average particle size distribution index GSDv of the toner is a ratio (D _84v / D _16v ) of the particle diameter D _16v at which the cumulative volume is 16% to the particle diameter D _84v at which the cumulative volume is 84% from the small diameter side. It refers to the square root and can be measured using the same device as the volume average particle diameter.

The electrostatic image developer is not particularly limited except that it contains a toner, and can have an appropriate component composition depending on the purpose.
When the toner is used alone, the electrostatic image developer is prepared as a one-component electrostatic image developer, and when used in combination with a carrier, the toner is prepared as a two-component electrostatic image developer.

The carrier used as the two-component electrostatic image developer is not particularly limited, and examples thereof include resin-coated carriers described in JP-A Nos. 62-39879 and 56-11461. A known carrier can be used.
The mixing ratio of the toner and the carrier in the electrostatic image developer is not particularly limited and can be appropriately selected depending on the purpose.

  Since the image forming method of the present invention uses the electrophotographic transfer paper of the present invention, the sheet elongation can be suppressed and has excellent reliability.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto. In the examples and comparative examples, “parts” means parts by mass unless otherwise specified.

Example 1
The pulp slurry of hardwood bleached kraft pulp (LBKP) 100 parts by mass with Niagara Beata (manufactured by Kumagai Riki Kogyo Co., Ltd.) was pulverized to a pulp slurry having a freeness of 350 ml and lighter than 100 parts by mass of pulp fiber solids. 10 parts by weight of calcium carbonate (Tamapearl TP-121, manufactured by Okutama Kogyo Co., Ltd.), 0.5 parts by mass of aluminum sulfate, 0.5 parts by mass of cationized starch (trade name: MS4600 manufactured by Nippon Food & Chemicals Co., Ltd.) 0.1 parts by mass of alkenyl succinic anhydride (Fibrane 81, manufactured by Oji National Co., Ltd.), 1.2 parts by mass of a crosslinking agent carbodiimide-based crosslinking agent (trade name: Carbodilite V-04, manufactured by Nisshinbo Industries, Ltd.) The mixture was diluted with white water to prepare a pulp slurry having a solid content of 0.3% by mass.

After stirring this pulp slurry for 2 hours, polyvinyl alcohol having a polymerization degree of 2400 (PVA624, Kuraray Co., Ltd.) was applied to both sides of the wet paper obtained by making paper using an oriented sheet former (manufactured by Kumagai Riki Kogyo Co., Ltd.). Applied) with a size press so that the coating weight is 2.3 g / m ² in dry weight, and after drying, smoothing is performed using a machine calendar so that the Oken smoothness is 30 seconds. To obtain a base material having a basis weight of 49 g / m ² .

Next, as a coating solution for forming a coating layer, 100% by mass of a pigment component [heavy calcium carbonate (trade name: Softon 2200, average particle size 1.0 μm, manufactured by Bihoku Flour Industry Co., Ltd.) %, Kaolin (Ultra White 90, average particle size 1.3 μm, Engelhard Co., Ltd.) 82% by mass], oxidized starch (Ace A Oji Cornstarch Co., Ltd.) 3% by mass (solid to pigment) Ratio; the same applies hereinafter) and a synthetic adhesive (LX407H, manufactured by Nippon Zeon Co., Ltd.) having a glass transition temperature of 0 ° C., 12% by mass, a mold release agent (paraffin wax HNP-10, manufactured by Nippon Seiki Co., Ltd.) The coating composition which mix | blended 5 mass% and the dispersing agent (Aron T-40 Toagosei Co., Ltd. product) 0.3 mass% was adjusted.
Subsequently, this coating composition was coated on both sides of the substrate with a blade coater so that the dry weight per side was 7.5 g / m ^2, and after drying, a white paper gloss was obtained with a super calendar at a roll temperature of 50 ° C. Was smoothed to give a transfer paper for electrophotography having a basis weight of 64 g / m ² .

(Example 2)
The pulp slurry of hardwood bleached kraft pulp (LBKP) 100 parts by mass with Niagara Beata (manufactured by Kumagaya Riki Kogyo Co., Ltd.) was pulverized to a pulp slurry with a freeness of 280 ml. 10 parts by weight of calcium carbonate (Tamapearl TP-121, manufactured by Okutama Kogyo Co., Ltd.), 0.5 parts by mass of aluminum sulfate, 0.5 parts by mass of cationized starch (trade name: MS4600 manufactured by Nippon Food & Chemicals Co., Ltd.) 0.1 parts by mass of alkenyl succinic anhydride (Fibrane 81, manufactured by Oji National Co., Ltd.), 1.0 part by mass of carbodiimide emulsion type cross-linking agent (trade name: Carbodilite E-01, manufactured by Nisshinbo Industries, Ltd.) The mixture was diluted with white water to prepare a pulp slurry having a solid content of 0.3% by mass.

After stirring this pulp slurry for 2 hours, polyvinyl alcohol having a polymerization degree of 2400 (PVA624, Kuraray Co., Ltd.) was applied to both sides of the wet paper obtained by making paper using an oriented sheet former (manufactured by Kumagai Riki Kogyo Co., Ltd.). Applied) with a size press so that the coating amount is 2.5 g / m ² in dry weight, and after drying, smoothing is performed using a machine calendar so that the Oken smoothness is 30 seconds. To obtain a base material having a basis weight of 49 g / m ² .

Next, as a coating solution for forming a coating layer, 100% by mass of a pigment component [heavy calcium carbonate (trade name: Softon 2200, average particle size 1.0 μm, manufactured by Bihoku Flour Industry Co., Ltd.) is 25 masses. %, Kaolin (Ultra White 90, average particle size 1.3 μm, Engelhard Co., Ltd.) 75% by mass], oxidized starch (Ace A Oji Cornstarch Co., Ltd.) 3% by mass (solid to pigment) Ratio; the same applies hereinafter) and 12% by mass of a synthetic adhesive (LX407H, manufactured by Nippon Zeon Co., Ltd.) having a glass transition temperature of 0 ° C., 2.5% by mass of a release agent (Carnauba wax, manufactured by Toa Kasei Co., Ltd.), The coating composition which mix | blended 0.3 mass% of dispersing agents (Aron T-40 Toagosei Co., Ltd. product) was prepared.
Subsequently, this coating composition was coated on both sides of the substrate with a blade coater so that the dry weight per side was 7.5 g / m ^2, and after drying, a white paper gloss was obtained with a super calendar at a roll temperature of 50 ° C. Was smoothed to give an electrophotographic transfer paper having a basis weight of 64 g / m ² .

(Example 3)
Beating pulp slurry of 80 parts by mass of LBKP with Niagara Beata (made by Kumagai Riki Kogyo Co., Ltd.) and pulp slurry having a freeness of 250 ml and pulp slurry of 20 parts by mass of NBKP with Niagara Beata (made by Kumagaya Rikyu Kogyo Co., Ltd.) 10 parts by weight of light calcium carbonate (Tama Pearl TP-121, manufactured by Okutama Kogyo Co., Ltd.) with respect to 100 parts by mass of pulp fiber solids, and aluminum sulfate 0.5 parts by mass, 0.5 parts by mass of cationized starch (trade name: MS4600, manufactured by Nippon Food Chemical Co., Ltd.), 0.1 parts by mass of alkenyl succinic anhydride (Fibran 81, manufactured by Oji National Corporation) Carbodiimide emulsion type cross-linking agent (trade name: Carbodilite E-01, manufactured by Nisshinbo Industries, Ltd. 3.5 parts by mass of the mixture is diluted with white water to prepare a solid concentration of 0.3 wt% pulp slurry.

After stirring the pulp slurry for 2 hours, polyvinyl alcohol having a polymerization degree of 2500 (trade name: JC-25) was applied to both sides of the wet paper obtained by paper making using an oriented sheet former (manufactured by Kumagai Riki Kogyo Co., Ltd.). , Manufactured by Nippon Vinegar Poval Co., Ltd.) with a size press device so that the coating amount is 2.0 g / m ² in terms of dry weight, and then, a crosslinking agent zirconium ammonium carbonate (trade name) : Cartabond ZA Liquid, Clariant Japan Co., Ltd.) was applied with a size press machine so that the coating amount was 1.5 g / m ² by dry weight. A base material having a basis weight of 44 g / m ² was obtained.

Next, as a coating solution for forming a coating layer, 100% by mass of a pigment component [heavy calcium carbonate (trade name: Softon 2200, average particle size: 1.0 μm, manufactured by Bihoku Flour Industry Co., Ltd.) %, Kaolin (Ultra White 90, average particle size 1.3 μm, Engelhard Co., Ltd.) 70% by mass], starch as an adhesive (Ace A Oji Cornstarch Co., Ltd.) 3% by mass (solid to pigment) Ratio; the same applies hereinafter) and a synthetic adhesive having a glass transition temperature of 56 ° C. (LX433C, manufactured by Nippon Zeon Co., Ltd.), 12% by mass, a crosslinking agent zirconium carbonate ammonium salt (trade name: Cartabond ZA Liquid, Clariant Japan Co., Ltd.) ) 0.3% by mass, release agent (rice wax, manufactured by Toa Kasei Co., Ltd.) 2.0% by mass, dispersant (Aron T-40 manufactured by Toa Gosei Co., Ltd.) 0.3% by mass To prepare a coated composition containing.
Subsequently, this coating composition was applied to both sides of the substrate by a blade coater so that the dry weight per side was 10.0 g / m ^2, and after drying, a white paper gloss was obtained with a super calendar at a roll temperature of 50 ° C. Was smoothed to give a transfer paper for electrophotography having a basis weight of 64 g / m ² .

Example 4
The pulp slurry of hardwood bleached kraft pulp (LBKP) 100 parts by mass with a Niagara Beata (manufactured by Kumagaya Riki Kogyo Co., Ltd.) was pulverized to 370 ml of pulp slurry, and the pulp fiber solid content was 100 parts by mass. 10 parts by weight of calcium carbonate (Tamapearl TP-121, manufactured by Okutama Kogyo Co., Ltd.), 0.5 parts by mass of aluminum sulfate, 0.5 parts by mass of cationized starch (trade name: MS4600 manufactured by Nippon Food & Chemicals Co., Ltd.) 0.1 parts by mass of alkenyl succinic anhydride (Fibran 81, manufactured by Oji National Co., Ltd.), 1.5 parts by mass of carbodiimide-based crosslinking agent (trade name: Carbodilite V-02, manufactured by Nisshinbo Co., Ltd.) These mixtures were diluted with white water to prepare a pulp slurry having a solid content concentration of 0.3% by mass.

After stirring this pulp slurry for 2 hours, polyvinyl alcohol (PVA117, Kuraray Co., Ltd.) having a polymerization degree of 1700 was applied to both sides of the wet paper obtained by making paper using an oriented sheet former (manufactured by Kumagai Riki Kogyo Co., Ltd.). Applied with a size press so that the coating weight is 3.0 g / m ² by dry weight, and after drying, smoothing is performed using a machine calendar so that the Oken smoothness is 30 seconds. To obtain a base material having a basis weight of 46 g / m ² .

Next, as a coating solution for forming a coating layer, 100% by mass of a pigment component [heavy calcium carbonate (trade name: Softon 2200, average particle size 1.0 μm, manufactured by Bihoku Flour Industry Co., Ltd.) is 25 masses. %, Kaolin (Ultra White 90, average particle size 1.3 μm, Engelhard Co., Ltd.) 60% by mass, light calcium carbonate (trade name: Calcite SA, average particle size 3.0 μm, Shiraishi Kogyo Co., Ltd.) 15% by mass), 3% by mass of oxidized starch (Ace A, manufactured by Oji Cornstarch Co., Ltd.) as an adhesive (solid ratio to pigment; the same applies hereinafter), and a synthetic adhesive having a glass transition temperature of 26 ° C. (Nipol 1577, Japan) Zeon Co., Ltd.) 12% by mass, crosslinker zirconium carbonate ammonium salt (trade name: Cartabond ZA Liquid, Clariant Japan Co., Ltd.) 0.3% by mass, mold release A coating composition containing 0.7% by mass (calcium stearate, trade name: LB131, manufactured by Modern Chemical Industry Co., Ltd.) and 0.3% by mass of a dispersant (Aron T-40 manufactured by Toa Gosei Co., Ltd.) It was adjusted.
Subsequently, this coating composition was applied to both sides of the substrate with a blade coater so that the dry weight per side was 9.0 g / m ^2, and after drying, a white paper gloss was obtained with a super calendar at a roll temperature of 50 ° C. Was smoothed to give a transfer paper for electrophotography having a basis weight of 64 g / m ² .

(Example 5)
The pulp slurry of hardwood bleached kraft pulp (LBKP) 100 parts by mass with Niagara Beata (manufactured by Kumagaya Riki Kogyo Co., Ltd.) was used to obtain a pulp slurry having a freeness of 250 ml and lighter than 100 parts by mass of pulp fiber solids. 10 parts by weight of calcium carbonate (Tamapearl TP-121, manufactured by Okutama Kogyo Co., Ltd.), 0.5 parts by mass of aluminum sulfate, 0.5 parts by mass of cationized starch (trade name: MS4600 manufactured by Nippon Food & Chemicals Co., Ltd.) 0.1 parts by mass of alkenyl succinic anhydride (Fibran 81, manufactured by Oji National Co., Ltd.), 2.3 parts by mass of a bulking agent (trade name: Muscat K-100, manufactured by Nikka Chemical Co., Ltd.) These mixtures were diluted with white water to prepare a pulp slurry having a solid content concentration of 0.3% by mass.

After stirring this pulp slurry for 2 hours, oxidized starch (trade name: Ace B, Oji Corn Starch Co., Ltd.) was formed on both sides of the wet paper obtained by making paper using an oriented sheet former (manufactured by Kumagaya Rikyu Kogyo Co., Ltd.). )) Was applied with a size press so that the coating amount was 1.5 g / m ² in terms of dry weight, and then a carbodiimide emulsion type cross-linking agent (trade name: Carbodilite E-01, Nisshinbo ( Co., Ltd.) was applied with a size press so that the coating amount was 1.5 g / m ² in dry weight, and after drying, smoothing was performed using a machine calendar so that the Oken type smoothness was 30 seconds. And a base material having a basis weight of 49 g / m ² was obtained.

Next, as a coating solution for forming a coating layer, 100% by mass of a pigment component [heavy calcium carbonate (trade name: Softon 2200, average particle size: 1.0 μm, manufactured by Bihoku Flour Industry Co., Ltd.) %, Kaolin (Ultra White 90, average particle size 1.3 μm, Engelhard Co., Ltd.) 70% by mass]], oxidized starch (Ace A Oji Cornstarch Co., Ltd.) 8% by mass (based on pigment) 12% by mass of a solid adhesive (Nipol 1577, manufactured by Nippon Zeon Co., Ltd.) having a glass transition temperature of 26 ° C. and a mold release agent (polyethylene wax, trade name: LB-PE, Modern Chemical Industries, Ltd.) The coating composition which mix | blended 1.0 mass% and the dispersing agent (Aron T-40 Toagosei Co., Ltd. product) 0.3 mass% was adjusted.
Subsequently, this coating composition was applied to both sides of the substrate with a blade coater so that the dry weight per side was 7.5 / m ^2, and after drying, a white paper gloss was obtained with a super calendar at a roll temperature of 50 ° C. Was smoothed to give a transfer paper for electrophotography having a basis weight of 64 g / m ² .

(Comparative Example 1)
The pulp slurry of hardwood bleached kraft pulp (LBKP) 100 parts by mass with Niagara Beata (manufactured by Kumagai Riki Kogyo Co., Ltd.) was pulverized to a pulp slurry having a freeness of 350 ml and lighter than 100 parts by mass of pulp fiber solids. 10 parts by weight of calcium carbonate (Tamapearl TP-121, manufactured by Okutama Kogyo Co., Ltd.), 0.5 parts by mass of aluminum sulfate, 0.5 parts by mass of cationized starch (trade name: MS4600 manufactured by Nippon Food & Chemicals Co., Ltd.) 0.1 parts by mass of alkenyl succinic anhydride (Fibran 81, manufactured by Oji National Co., Ltd.) was added, and these mixtures were diluted with white water to prepare a pulp slurry having a solid content concentration of 0.3% by mass.

After stirring this pulp slurry for 2 hours, oxidized starch (trade name: Ace B, Oji Corn Starch Co., Ltd.) was formed on both sides of the wet paper obtained by making paper using an oriented sheet former (manufactured by Kumagaya Rikyu Kogyo Co., Ltd.). )) Is applied with a size press so that the coating amount is 1.5 g / m ² in terms of dry weight, and after drying, it is smoothed with a machine calendar so that the Oken smoothness becomes 30 seconds. The base material with a basic weight of 44 g / m < ² > was obtained by processing.

Next, as a coating solution for forming a coating layer, 100% by mass of a pigment component [heavy calcium carbonate (trade name: Softon 2200, average particle size: 1.0 μm, manufactured by Bihoku Flour Industry Co., Ltd.) %, Kaolin (Ultra White 90, average particle size 1.3 μm, Engelhard Co., Ltd.) 70% by mass], starch as an adhesive (Ace A Oji Cornstarch Co., Ltd.) 3% by mass (solid to pigment) Ratio: the same applies hereinafter) and 12% by mass of a synthetic adhesive (LX407H, manufactured by Nippon Zeon Co., Ltd.) having a glass transition temperature of 0 ° C., and 0.3% by mass of a dispersant (Aron T-40 manufactured by Toa Gosei Co., Ltd.) The blended coating composition was prepared.
Subsequently, this coating composition was applied to both sides of the substrate by a blade coater so that the dry weight per side was 10.0 g / m ^2, and after drying, a white paper gloss was obtained with a super calendar at a roll temperature of 50 ° C. Was smoothed to give an electrophotographic transfer paper having a basis weight of 64 g / m ² .

(Comparative Example 2)
Beating pulp slurry of 80 parts by mass of LBKP with Niagara Beata (made by Kumagai Riki Kogyo Co., Ltd.) and pulp slurry having a freeness of 250 ml and pulp slurry of 20 parts by mass of NBKP with Niagara Beata (made by Kumagaya Rikyu Kogyo Co., Ltd.) 10 parts by weight of light calcium carbonate (Tama Pearl TP-121, manufactured by Okutama Kogyo Co., Ltd.) with respect to 100 parts by mass of pulp fiber solids, and aluminum sulfate 0.5 parts by mass, 0.5 parts by mass of cationized starch (trade name: MS4600, manufactured by Nippon Food Chemical Co., Ltd.), 0.1 parts by mass of alkenyl succinic anhydride (Fibran 81, manufactured by Oji National Corporation) And these mixtures were diluted with white water to prepare a pulp slurry having a solid content concentration of 0.3% by mass.

After stirring this pulp slurry for 2 hours, polyvinyl alcohol (trade name: JC-25) having a polymerization degree of 2500 was applied to both sides of the wet paper obtained by making paper using an oriented sheet former (manufactured by Kumagai Riki Kogyo Co., Ltd.). , Manufactured by Nippon Vinegar Poval Co., Ltd.) with a size press device so that the coating amount is 2.0 g / m ² in terms of dry weight, and after drying, it is dried using a machine calender. Was smoothed so as to be 30 seconds to obtain a substrate having a basis weight of 44 g / m ² .

Next, as a coating solution for forming a coating layer, 100% by mass of a pigment component [heavy calcium carbonate (trade name: Softon 2200, average particle size: 1.0 μm, manufactured by Bihoku Flour Industry Co., Ltd.) %, Kaolin (Ultra White 90, average particle size 1.3 μm, Engelhard Co., Ltd.) 70% by mass], starch as an adhesive (Ace A Oji Cornstarch Co., Ltd.) 3% by mass (solid to pigment) Ratio: the same applies hereinafter) and 12% by mass of a synthetic adhesive (LX433C, manufactured by Nippon Zeon Co., Ltd.) having a glass transition temperature of 56 ° C. and 0.3% by mass of a dispersant (Aron T-40 manufactured by Toa Gosei Co., Ltd.) The blended coating composition was prepared.
Subsequently, this coating composition was applied to both sides of the substrate by a blade coater so that the dry weight per side was 10.0 g / m ^2, and after drying, a white paper gloss was obtained with a super calendar at a roll temperature of 50 ° C. Was smoothed to give a transfer paper for electrophotography having a basis weight of 64 g / m ² .

(Comparative Example 3)
The pulp slurry of hardwood bleached kraft pulp (LBKP) 100 parts by mass with Niagara Beata (manufactured by Kumagaya Riki Kogyo Co., Ltd.) was used to obtain a pulp slurry having a freeness of 250 ml and lighter than 100 parts by mass of pulp fiber solids. 10 parts by weight of calcium carbonate (Tamapearl TP-121, manufactured by Okutama Kogyo Co., Ltd.), 0.5 parts by mass of aluminum sulfate, 0.5 parts by mass of cationized starch (trade name: MS4600 manufactured by Nippon Food & Chemicals Co., Ltd.) 0.1 parts by mass of alkenyl succinic anhydride (Fibran 81, manufactured by Oji National Co., Ltd.), 1.8 parts by mass of bulking agent (trade name: MASKUT K-100, manufactured by Nikka Chemical Co., Ltd.) were added, These mixtures were diluted with white water to prepare a pulp slurry having a solid content concentration of 0.3% by mass.

After stirring this pulp slurry for 2 hours, polyvinyl alcohol (trade name: PVA117, with a polymerization degree of 1700) was formed on both sides of the wet paper obtained by making paper using an oriented sheet former (manufactured by Kumagai Riki Kogyo Co., Ltd.). Kuraray Co., Ltd.) is applied with a size press machine so that the coating amount is 2.3 g / m ² in dry weight, and after drying, the Oken type smoothness is set to 30 seconds by a machine calendar. The substrate was smoothed to obtain a base material having a basis weight of 49 g / m ² .

Next, as a coating solution for forming a coating layer, 100% by mass of a pigment component [heavy calcium carbonate (trade name: Softon 2200, average particle size: 1.0 μm, manufactured by Bihoku Flour Industry Co., Ltd.) %, Kaolin (Ultra White 90, average particle size 1.3 μm, Engelhard Co., Ltd.) 70% by mass]], oxidized starch (Ace A Oji Cornstarch Co., Ltd.) 8% by mass (based on pigment) Solid ratio; the same applies hereinafter) and synthetic adhesive (LX407H, manufactured by Nippon Zeon Co., Ltd.) having a glass transition temperature of 0 ° C. 12% by mass, dispersant (Aron T-40 manufactured by Toa Gosei Co., Ltd.) 0.3% by mass The coating composition which mix | blended was adjusted.
Subsequently, this coating composition was applied to both sides of the substrate with a blade coater so that the dry weight per side was 7.5 / m ^2, and after drying, a white paper gloss was obtained with a super calendar at a roll temperature of 50 ° C. Was smoothed to obtain 25% electrophotographic transfer paper having a basis weight of 64 g / m ² .

(Comparative Example 4)
A commercially available coated paper, OK Coat L 64.0 g / m ² (Oji Paper Co., Ltd.) was used.

(Comparative Example 5)
Royal Coat L64.0 g / m ² (manufactured by Oji Paper Co., Ltd.), which is a commercially available coated paper for printing, was used.

(Comparative Example 6)
Pegasus 64.0 g / m ² (manufactured by Nippon Paper Industries Co., Ltd.), which is a commercially available finely coated paper for printing, was used.

(Comparative Example 7)
The pulp slurry of hardwood bleached kraft pulp (LBKP) 100 parts by mass with Niagara Beata (manufactured by Kumagai Riki Kogyo Co., Ltd.) was pulverized to a pulp slurry having a freeness of 350 ml and lighter than 100 parts by mass of pulp fiber solids. 10 parts by weight of calcium carbonate (Tamapearl TP-121, manufactured by Okutama Kogyo Co., Ltd.), 0.5 parts by mass of aluminum sulfate, 0.5 parts by mass of cationized starch (trade name: MS4600 manufactured by Nippon Food & Chemicals Co., Ltd.) 0.1 parts by mass of alkenyl succinic anhydride (Fibran 81, manufactured by Oji National Co., Ltd.) was added, and these mixtures were diluted with white water to prepare a pulp slurry having a solid content concentration of 0.3% by mass.

After stirring this pulp slurry for 2 hours, oxidized starch (trade name: Ace B, Oji Corn Starch Co., Ltd.) was formed on both sides of the wet paper obtained by making paper using an oriented sheet former (manufactured by Kumagaya Rikyu Kogyo Co., Ltd.). )) Is applied with a size press so that the coating amount is 1.5 g / m ² in terms of dry weight, and after drying, it is smoothed with a machine calendar so that the Oken smoothness becomes 30 seconds. The base material with a basic weight of 44 g / m < ² > was obtained by processing.

Next, as a coating solution for forming a coating layer, 100% by mass of a pigment component [heavy calcium carbonate (trade name: Softon 2200, average particle size 1.0 μm, manufactured by Bihoku Flour Industry Co., Ltd.) %, Kaolin (Ultra White 90, average particle size 1.3 μm, Engelhard Co., Ltd.) 50 mass%, light calcium carbonate (trade name: heavy coal N-35, average particle size 6.3 μm, Maruo calcium ( 30% by mass)), 3% by mass of oxidized starch (Ace A manufactured by Oji Cornstarch Co., Ltd.) as an adhesive (solid ratio to pigment; the same applies hereinafter) and a synthetic adhesive (LX407H having a glass transition temperature of 0 ° C.) , Manufactured by Nippon Zeon Co., Ltd.) 10% by weight, release agent (polyethylene wax, trade name: LB-PE, manufactured by Modern Chemical Industry Co., Ltd.) 0.3% by weight, dispersant (Aron T-40 Toa Gosei ( stock) ) To prepare a coated composition containing 0.3 mass%.
Subsequently, this coating composition was applied to both sides of the substrate by a blade coater so that the dry weight per side was 10.0 g / m ^2, and after drying, a white paper gloss was obtained with a super calendar at a roll temperature of 50 ° C. Was smoothed so as to be 26% to obtain an electrophotographic transfer paper having a basis weight of 64 g / m ² .

  Table 1 shows the results of evaluating the runnability and image quality of the papers of the above examples and comparative examples, together with various characteristic values and production conditions of the coated paper.

<Quality evaluation method>
The measurement / evaluation directions and evaluation criteria for various items shown in Table 1 are as follows.
(1) Basis weight It measured by the method of JIS P-8124.
(2) Blank paper glossiness Measured at an incident angle of 75 degrees according to JIS P-8142.
(3) Thickness and density of paper Measured by the method of JIS P-8118.
(4) Tensile modulus of paper According to the method of JIS P-8111, with respect to the CD direction of the paper conditioned to a standard state, the width is 15 mm and the length is 150 mm as a sample, and the tensile speed is evaluated as 5 mm / min. It was calculated from the obtained value.
(5) Static friction coefficient of paper surface The static friction coefficient of the paper surface was measured by the method described above.

(6) Measurement of paper elongation The measurement of the paper elongation was carried out using a dry indirect electrophotographic digital color copying machine Color DocuTech 60 manufactured by Fuji Xerox. The pressure belt (product code CT400005) of the fixing device of Color DocuTech 60 is made of a material mainly composed of a fluororubber composition, and the ten-point surface roughness Rz is 3 μm. The process speed was set to 340 mm / s.

First, the paper of each example and comparative example was cut into A4 size (210 × 297 mm) sheets, which were conditioned at 23 ° C. and 50% RH for 24 hours or more, and then the length of the short side of the sheet was adjusted. Measurements were made at two locations on both ends. Next, 10 sheets were run one by one with the long side of the sheet (longitudinal sheet) as the leading edge. The paper that was output with no image on it and was output in a blank state was conditioned again at 23 ° C. and 50% RH for 24 hours or more, and the length of the short side of the sheet at that time was measured at two locations on both ends.
The sheet elongation amount was obtained by subtracting the average value of the short side length before traveling from the average value of the short side length after traveling (after fixing).

(7) Image Contrast Image ID No. N1 of ISO / JIS-SCID sample (published by Japan Standards Association) for paper seasoned in 23 ° C. 50% RH environment by DocuColor 1250CP manufactured by Fuji Xerox Co., Ltd. installed in 23 ° C. 50% RH environment (Image Name Portrait) was output and the image contrast was evaluated according to the following evaluation criteria.
The toner used for image formation is a styrene-n-butyl acrylate resin binder resin, and a resin particle dispersion in which resin particles are dispersed and a colorant dispersion in which a colorant is dispersed are mixed. The resin particles and the colorant are aggregated to a toner particle diameter, and the obtained aggregate is produced through a method of heating and fusing to a temperature higher than the glass transition point of the resin. This toner had a volume average particle size of 5.5 μm, a shape factor SF1 of 132, and a GSDv of 1.22. In forming an image, this toner was combined with a resin-coated carrier and used as a two-component developer.
A: Excellent with no difference between the gloss of the image area and the gloss of the white paper.
○: Good with little difference between gloss of image area and gloss of blank paper.
Δ: The difference between the gloss of the image portion and the gloss of the white paper is slightly inferior.
X: The difference between the gloss of the image portion and the gloss of the white paper is large, which is remarkably inferior. Image quality evaluation

<Evaluation results>
As is apparent from Table 1, the electrophotographic transfer paper of the present invention has a sheet elongation amount of 1 mm or less in any of the embodiments, which is a level that does not cause a problem in practice, and is generated along with the sheet elongation. No paper wrinkles were found. In addition, although it is excellent in image contrast and lightweight coated paper, compared to conventional lightweight coated paper, the amount of paper elongation at the time of fixing in an electrophotographic copying machine and printer can be kept low, In addition, it was found that the gloss of white paper is high, the image contrast is excellent, and the product value is extremely large.

1 is a schematic configuration diagram illustrating an example of an image output apparatus used in an image forming method of the present invention. 1 is a schematic configuration diagram illustrating an example of a heat fixing device used in an image forming method of the present invention.

Explanation of symbols

1 Heat roll 2 Pressure belt 3 Heat source 4 Base material (core)
5 Elastic layer 6 Fixing member surface layer 7 Toner image 9, 10, 11 Roll 12 Pad member 11 Photosensitive member (latent image carrier)
DESCRIPTION OF SYMBOLS 12 Roller type charger 13 Exposure apparatus 14a, 14b, 14c, 14d Developing device 14 Developing apparatus 15 Intermediate transfer body 16 Cleaner 17 Photostatic dischargers 18a, 18b, 18c Support roller 19 Transfer roller 20 Transfer object

Claims (3)

The base weight which has a pulp fiber as a main component, and the coating layer which has a pigment and an adhesive as a main component on the outermost surface of both surfaces of this base material, and the basic weight measured based on JIS P-8124 is In the electrophotographic transfer paper having a weight of 40 g / m ² or more and 85 g / m ² or less,
A transfer sheet for electrophotography, wherein the surface has a static friction coefficient of 0.85 or less and satisfies the following formula (1).
Formula (1) 3.5 × 10 ⁵ ≦ t × E
[In the formula (1), t represents the thickness (μm) of the electrophotographic transfer paper, and E represents the tensile modulus (Mpa) in the CD direction of the electrophotographic transfer paper. ]   2. The electrophotographic transfer paper according to claim 1, wherein the glossiness of the white paper measured based on JIS P-8142 is 30% or more. A latent image forming step of forming a latent image on the latent image carrier; a developing step of developing the latent image using an electrophotographic developer to obtain a toner image; and a transferring step of transferring the toner image to a transfer medium And a fixing step of heat-pressing the toner image on the surface of the transfer body using a fixing device, and forming an image at a constant process speed,
An image forming method, wherein the transfer object is the electrophotographic transfer paper according to claim 1.

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