JP4432686B2 - Image forming method - Google Patents

Description

  The present invention relates to an image forming method for an indirect dry electrophotographic copying machine or printer, and more particularly to a full color image forming method.

  In recent years, with the advancement of electrophotographic recording devices, using coated paper that has been used for commercial printing such as offset printing, digital signals can be colored on demand on glossy coated paper by electrophotography. Graphic arts such as so-called on-demand printing for printing, and practical use in the short run printing area are beginning to become remarkable.

  In this specification, the term “graphic arts” refers to the entire industry / department related to the production of printed materials, such as original prints such as prints, handwritten drawings, and paintings that are printed with a small number of copies. This refers to a business area related to the production of printed materials by a mass production method called copying, copying, and re-production.

  In the short run printing area, not only monochrome printing making use of the characteristics of plateless printing in electrophotography but also image formation targeting a short run color printing area as typified by Color DocuTech 60 manufactured by Fuji Xerox Co., Ltd. Devices have been developed, and significant progress is being made in terms of image quality, transfer paper compatibility, product price, and price per sheet (see Non-Patent Document 1).

For high image quality in the graphic arts area, instead of the PPC paper and printer paper normally used so far, it has high white paper gloss that has been used in the field of commercial printing from the vividness of the obtained image. An increasing number of cases use coated paper (commercial printing coated paper).
However, when commercial printing coated paper is used in conventional electrophotographic full-color copying machines and printers, many troubles occur in the transfer process, fixing process, and further post-processing process from the paper feeding section.

Regarding paper feed quality, paper feed failure is likely to occur in a high humidity environment. Usually, coated paper for commercial printing is provided with a coating layer containing a white pigment and an adhesive as main components on its surface in order to impart white paper gloss. This coating layer is subjected to surface smoothing by calendering after coating the solution for forming the coating layer, so that the layer once formed by coating is crushed by the pressure applied during calendering. , There are very few voids in the layer. For this reason, when water molecules enter between the surface of the paper that has been stored in a highly humid environment and the surface of the paper, a water film is formed between the coating layers that have a low moisture absorption capacity. The adhesive strength of the is increased, and misfeeds and double feeds are likely to occur.
In contrast, a technique for suppressing an increase in the coefficient of friction on the paper surface in a high-humidity environment (see Patent Document 1) and a technique for reducing adhesion between sheets due to swelling of the base material at high humidity (Patent Document 2). Have been proposed).

In the transfer unit, immediately after the toner is transferred to the charged paper, the charged paper causes electrostatic adsorption to the transfer member in the paper transport direction, causing a running trouble. For this reason, it is necessary to devise a paper design or a transfer system for controlling the paper behavior in the transfer process.
Furthermore, in the fixing section, as described above, the coated paper for commercial printing has a collapsed coating layer, and the voids in the layer are very small, resulting in a decrease in air permeability, and blisters are likely to occur during fixing. Become. The blister is a fine gap generated on the surface of the toner image portion. The generation of fine voids causes moisture in the paper to become water vapor due to heating during fixing, and when the air permeability of the paper is low, the water vapor is not discharged, resulting in an increase in the water vapor pressure in the paper. This is caused by the phenomenon of being discharged through the layer (image).

On the other hand, in order to suppress the occurrence of blisters at the time of fixing, a technique for specifying the air permeability of the coated paper to be a certain value or less; for example, a technique for setting the air permeability to 4000 seconds or less (for example, Patent Document 3, 4), and a technique of a pigment used for a coating layer for achieving such air permeability (see Patent Document 5, etc.).
Moreover, in these coated papers for printing, when the water | moisture content change in a paper arises, the dimension of a paper tends to change. In the case of an indirect dry electrophotographic full-color copying machine and printer, the amount of water in the paper changes when the toner is heat-fixed on the paper, so that the paper after image formation is curled. In order to cope with this problem, it is important to control the expansion and contraction of the paper, and it is necessary to study a paper design and fixing system.

On the other hand, when the toner is melt-fixed, an adhesive force is generated between the melted toner and the fixing member, and in the case of coated paper having a relatively high gloss, the paper cannot be quickly released from the fixing member. A defect mark remains or cannot be peeled off, and a jam occurs at the fixing portion. These phenomena are likely to occur in coated paper having a low paper basis weight.
On the other hand, a technique for setting the smoothness of the base material as a coated paper to 100 seconds or more and not performing a smoothing process during processing (see Patent Document 6) or a coating to reduce the adhesiveness of the coating layer. Attempts have been made to reduce the wrapping of the paper around the fixing device by a technique (see Patent Document 7) that improves the minimum film-forming temperature of the working layer latex.

  In addition, the toner used in the graphic arts area and the fixing device can be used for thin paper and thick paper. A toner material that can be easily fixed to a film or the like, and that can be fixed at low temperature that can suppress power consumption even when fixing coated paper or cardboard is essential. Fixing at a low temperature or low pressure reduces the stress on the transfer paper, and can suppress problems such as misregistration because the transfer paper can be prevented from stretching, curling and wavy.

  Further, in order to avoid image defects such as spots and streaks due to oil and poor writing performance, an oilless fixing device and an oilless toner containing a release material inside the toner are required. Furthermore, in order to achieve image durability that is comparable to normal printed images and does not cause problems under various usage conditions, the resin properties used in conventional toners must be further improved. I must.

  In addition, to meet the demand for price reduction per sheet, it is necessary to reduce toner consumption by reducing the particle size of the toner and optimizing the amount of colorant, which also leads to uniformity in image quality. Will also be easily affected. In addition, by realizing a more reliable image forming system, it is possible to reduce the amount of sag (waste output for obtaining stable image quality) when producing printed materials and to reduce maintenance load. In practice, it is important to keep the price per piece low.

  Furthermore, in order to make the gloss characteristics of the image more flexible and uniform, it is important to control the viscoelasticity of the toner and optimize the fixing device. In order to obtain a high-quality image based on offset printing, it is important to increase the market value to achieve the optimum gloss for the paper used. Optimization is necessary.

As described above, in order to meet the demands of graphic arts and short run printing areas, a technique in which the conventional electrophotographic technique is further advanced as a total system is required. In particular, in the short run market, there is an increasing demand to use coated paper with a low basis weight of 100 g / m ² or less for the production of leaflets, pamphlets, leaflets, small-scale magazines, and the like.

However, as described above, when using a low basic weight coated paper for commercial printing, it may not be practically used because it may cause wrapping or spot-like image defects due to poor peeling particularly in the fixing step. . In addition, even when coated paper using a technique for reducing the wrapping of the conventional paper around the fixing device as disclosed in Patent Document 6 and Patent Document 7 is employed, in oil-less fixing that does not use oil at the time of fixing. Has a problem that almost no effect is recognized.
JP 2002-88680 A Japanese Patent Laid-Open No. 11-174713 Japanese Patent No. 2218894 Japanese Patent No. 2676291 Japanese Patent No. 2745431 JP 2002-341582 A Japanese Patent Laid-Open No. 7-219262 Journal of the Imaging Society of Japan Vol. 40, no. 2, 2001

  An object of the present invention is to solve the above problems. That is, the present invention provides image defects caused by wrapping around a fixing device and peeling failure from the fixing device when an image is formed on a coated paper by a full-color copying machine and printer using an indirect dry electrophotographic method. It is an object of the present invention to provide an image forming method capable of suppressing generation.

  As a result of earnest research to achieve the above-mentioned problems, the present inventors combined a coated paper having a coating layer with excellent surface smoothness on at least one surface of a substrate and a small-diameter toner. It has been found that when an unfixed toner image is formed using an electrophotographic method, it is possible to suppress the wrapping phenomenon around the fixing device and image defects due to poor peeling from the fixing device, regardless of the configuration of the fixing device. That is, the present invention

<1>
A fixing step of fixing an unfixed toner image formed on the surface of the coated paper provided with the coating layer by heating and pressing, and forming an image;
The coated paper has a base material and a coating layer containing a pigment and / or a colorant as a main component on at least one side of the base material, and the unfixed toner image is made of toner containing a release agent. In the image forming method,
The volume average particle size of the toner is at 5μm or less, the Oken type smoothness of the surface coating layer is provided in the coated paper Ri der least 500 seconds, a basis weight of the coated paper is 100 g / m ² or less, and, CD direction of the tensile modulus of the coated paper is an image forming method, comprising der Rukoto least 5000 MPa.

<2>
The image forming method according to <1>, wherein a maximum toner amount per single color when the unfixed toner image is formed is 0.35 mg / cm ² or less.

< 3 >
The image forming method according to <1> or <2> , wherein the content of the release agent contained in the toner is 5% by mass or more.

< 4 >
<1> to < 3 > according to any one of <1> to < 3 >, wherein the coating amount per one side of the substrate when forming the coating layer is 5 g / m ² or more in terms of solid content. An image forming method.

< 5 >
The fixing step uses a fixing device including a pair of rolls whose outer peripheral surfaces are in contact with each other to form a nip portion,
Any one of <1> to < 4 >, wherein the coated paper on which the unfixed toner image is formed on the surface of the coating layer is inserted into the nip portion and heated and pressed. Or the image forming method according to any one of the above.

< 6 >
In the fixing step, the outer peripheral surfaces of the endless belt and the heating roll having an elastic layer that are in contact with each other face to face each other, and the inner peripheral surface of the endless belt so as to press the outer peripheral surface of the heating roll. And a fixing device including a pressure applying member arranged
Any one of <1> to < 4 >, wherein the coated paper on which the unfixed toner image is formed on the surface of the coating layer is inserted into the nip portion and heated and pressed. Or the image forming method according to any one of the above.

< 7 >
The fixing step includes a pair of endless belts that form opposed contact areas in which the outer peripheral surfaces of each other are opposed to each other along the rotation direction, and the pair of endless belts located upstream of the opposed contact area in the rotation direction. Using a fixing device including a pair of rolls that press the peripheral surface to form a nip portion,
The coated paper on which the unfixed toner image is formed on the surface of the coating layer is inserted into the nip portion and heated and pressurized, and then held between the pair of endless belts in the rotational direction of the opposed contact region. <1> to < 4 >, wherein the cooling is forcibly cooled while being conveyed to the downstream side, and is separated from the pair of endless belts while passing through the opposed contact region. An image forming method.

  As described above, according to the present invention, when an image is formed on a coated paper by a full-color copying machine and a printer using an indirect dry electrophotographic method, wrapping around the fixing device or peeling from the fixing device. It is possible to provide an image forming method capable of suppressing the occurrence of image defects due to defects.

  The image forming method of the present invention includes a fixing step of fixing an unfixed toner image formed on the surface of the coated paper on which the coating layer is provided by heating and pressing to form an image. An image forming method wherein paper has a base material and a coating layer containing a pigment and / or a colorant as a main component on at least one side of the base material, and the unfixed toner image is made of toner containing a release agent The volume average particle diameter of the toner is 5 μm or less, and the Oken smoothness of the surface of the coated paper on which the coating layer is provided is 500 seconds or more.

The present inventors have wrapping or peeling in the fixing step when using coated paper used for image formation by electrophotography, particularly coated paper having a low basis weight such as a basis weight of 100 g / m ² or less. As a result of intensive studies to prevent image defects due to defects, the present invention has been found. Details will be described below.

First, when an image is formed by electrophotography using coated paper, image defects associated with winding and peeling defects are caused by the fixing member such as a roll and the surface of the coated paper when the toner is melted in the fixing process. This occurs when the adhesive force with the toner image increases and the stiffness of the coated paper cannot overcome this adhesive force. This phenomenon becomes more noticeable in coated paper used for commercial printing, where the coated paper is weak and particularly has a basis weight of 100 g / m ² or less.

Therefore, in order to solve the image defect due to winding or peeling failure, the most obvious solution is to strengthen the stiffness of the coated paper. However, strengthening the stiffness of the coated paper basically increases the basis weight and the paper thickness, and consequently restricts the use application of the coated paper, so it is not a radical solution.
Therefore, the present inventors examined a solution that does not depend only on the stiffness of the coated paper. As a result, it was considered important to suppress the adhesive force between the fixing member and the toner image on the coated paper surface.

In order to suppress the adhesive force, in other words, it is important to improve the releasability between the fixing member and the toner image on the coated paper surface. In order to improve the releasability, the amount of the release agent blended in the toner is also important to some extent. However, as a result of intensive studies by the present inventors, in order to improve the releasability, the most important condition is essentially the release agent actually present at the interface between the fixing member and the toner image at the time of fixing. The amount (effective amount) and the presence state of the release agent, that is, the uniformity were found.
Accordingly, the present inventors have considered that it is necessary to efficiently and uniformly elute the release agent contained in the toner during fixing. Here, the elution of the release agent contained in the toner is a phenomenon that occurs due to heating and pressurization at the time of fixing. Therefore, in order to dissolve the release agent efficiently and uniformly, [1] The above two points are important: sufficient heat is quickly transmitted to the toner, and [2] the toner is easily crushed by pressure.

Here, the present inventors diligently studied the conditions for achieving the item [1]. As a result, the smaller the maximum toner amount per single color when an unfixed toner image is formed, the better, 0.35 mg / cm ^2. It has been found that the following is effective, and is effective from being 0.30 mg / m ² or less. In order to reduce the maximum amount of toner, it is necessary to use a toner having a small particle diameter. In the present invention, the volume average particle diameter of the toner needs to be 5 μm or less, and 4 μm or less. Is more preferable.

When the volume average particle diameter of the toner is 5 μm or less, the amount of toner is small, so that sufficient heat is quickly transmitted to the toner during fixing, and the release agent in the toner is efficiently and uniformly eluted. be able to. In addition, if such a small diameter toner is used, a higher-definition image can be simultaneously formed. On the other hand, when the volume average particle diameter of the toner exceeds 5 μm, the toner amount cannot be reduced, or a gap is generated between the toner particles and the image quality is deteriorated.
The volume average particle diameter of the toner is preferably 2 μm or more in order to ensure chargeability. Further, from a practical point of view such as securing the image density of the image, the maximum toner paste amount is preferably 0.25 mg / m ² or more.

  On the other hand, as a condition for achieving the above item [2], it is important that the surface of the coated paper provided with the coating layer (hereinafter sometimes simply referred to as “coated paper surface”) is smooth. is there. However, it is not necessary to simply have excellent smoothness, and it is necessary to ensure sufficient smoothness in relation to the particle size of the toner used. In the present invention, since a small diameter toner having a volume average particle diameter of 5 μm or less is used in the present invention, if the smoothness of the coated paper surface is insufficient, the small diameter toner is buried in the dent on the coated paper surface. It is because it ends. That is, in this case, sufficient pressure is not applied to the toner buried in the dent on the surface of the coated paper even by pressurization at the time of fixing, and it becomes difficult for the toner to be collapsed. Cannot be eluted.

  Accordingly, the smoothness of the coated paper surface needs to be 500 seconds or more in terms of Oken smoothness, and more preferably 700 seconds or more. Moreover, if such coated paper with high smoothness is used, a higher gloss image can be formed at the same time. The higher the smoothness of the coated paper surface, the better. However, it is preferable for practical use that the Oken type smoothness is 10,000 seconds or less.

  As described above, according to the image forming method of the present invention, a small-diameter toner having a volume average particle diameter of 5 μm or less and a coated paper having a surface roughness of 500 seconds or more are used in combination. The adhesive force between the fixing member and the toner image on the coated paper surface during fixing can be reduced, so that it is possible to suppress the wrapping around the fixing device and the occurrence of image defects due to poor peeling from the fixing device. it can.

In addition, as described above, the image forming method of the present invention secures the stiffness of the coated paper, which has a certain degree of correlation with the basis weight, and is accompanied by wrapping around the fixing device and defective peeling from the fixing device. Instead of suppressing image defects, these problems are solved by reducing the adhesive force between the fixing member and the toner image on the coated paper surface during fixing.
Therefore, the image forming method of the present invention is to provide a basis weight of 100 g / m ² or less of lightweight coated paper, a shall be able to exert a sufficient effect, and more preferably 90 g / m ² This is also effective in the following.

In order to supply a sufficient amount of the release agent to the interface between the fixing member at the time of fixing and the toner image on the coated paper surface, the content of the release agent contained in the toner is 5% by mass or more. It is preferable that the content is 6% by mass or more.
When the content is less than 5% by mass, a sufficient amount of the release agent cannot be supplied to the interface between the fixing member and the toner image on the surface of the coated paper, and the releasability deteriorates to the fixing device. In some cases, an image defect may occur due to the winding of the toner image or the peeling failure from the fixing device.
However, if the content of the release agent in the toner is too large, the content may be reduced because writing performance on the image surface with a ballpoint pen or the like may cause a sticky feeling on the image surface. It is preferable that it is 25 mass% or less.

In addition, the image forming method of the present invention is not capable of overcoming the adhesive force between the fixing member and the toner image on the coated paper surface at the time of fixing, so that it can be wrapped around the fixing device or peeled off from the fixing device. The weakness of the coated paper that causes image defects due to defects is compensated by weakening the adhesive force.
However, when the stiffness of the coated paper is too weak, there is a case where such a compensation effect of weakening the adhesive force is insufficient. Therefore, it is preferable that the strength of the coated paper is secured to a certain level or more, specifically, the tensile elastic modulus in the CD direction by the method defined in JISP8113 is preferably 3000 MPa or more, It is preferably 3500 MPa or more. In this case, the resistance against the bending force applied to the coated paper becomes easy to work, and the resistance against the force in the winding direction works, so that the winding hardly occurs. In the image forming method of the present invention, coated paper having a tensile elastic modulus in the CD direction of 5000 MPa or more is used .
Here, the CD direction (Cross Direction) means a direction perpendicular to the flow direction of the paper machine when the coated paper base material is manufactured, and generally the orientation of the fibers in the base material. Means the direction perpendicular to the current direction.

However, the stiffness is weak coated paper, such as less than CD direction tensile modulus 3000 MPa (e.g., basis weight coated paper of 40g / m ² ~70g / m ² about range) forming an image using Sometimes you want to. In this case, by increasing the content of the release agent in the toner, it is possible to prevent the deterioration of peelability due to the weakness of the coated paper.
However, on the other hand, the release agent remains on the image surface after image formation. Therefore, when the content of the release agent in the toner is large as described above, writing when writing on the image surface with a ballpoint pen or the like. In some cases, the image quality may deteriorate or the image surface may become sticky.
Therefore, if the content of the release agent in the toner can be minimized as long as the releasability can be sufficiently secured, the above two trade-off problems should be dealt with in a balanced manner. Can do.

In order to intensively study such problems, the present inventors have used a coated paper having a basis weight of 85 g / m ² and a Oken type smoothness of 500 seconds or more (a variety of commercially available coated papers and Fuji, using a coated paper prepared by a conventional method so as to improve the tensile elastic modulus in the CD direction) and a toner having a volume average particle diameter of 3.5 μm with a changed content of paraffin Wax as a release agent. When an image was formed at a Red 100% area ratio using an image forming apparatus (DocuCenterColor400) manufactured by Xerox Co., Ltd., the occurrence frequency of winding around the fixing device and the degree of image defects due to poor peeling were evaluated. The evaluation results are shown in FIG.

FIG. 1 shows a fixing device when an image is formed using various coated papers having a basis weight of 85 g / m ² , Oken type smoothness of 500 seconds or more, and various toners having a volume average particle diameter of 3.5 μm. 3 is a graph showing image defects due to winding and peeling failure with respect to the content of a release agent in toner and the tensile modulus in the CD direction of coated paper.
As a result of intensive studies by the present inventors, if the toner and coated paper satisfying the area indicated by the oblique line with the curve shown in FIG. 1 as the boundary line are used, it is almost surely caused by winding around the fixing device and defective peeling. It was confirmed that image defects could be eliminated.

Accordingly, when the image forming method of the present invention is carried out, particularly excellent effects are obtained with respect to image defects due to winding around the fixing device and peeling failure within the region indicated by the oblique lines in FIG. be able to. In addition, if carried out under conditions in the vicinity of the curve in FIG. 1, the content of the release agent can be minimized while suppressing image defects due to winding around the fixing device and peeling failure. It is also possible to suppress a decrease in writability on the image surface and a sticky feeling on the image surface in a balanced manner.
In addition, the area | region shown with the oblique line of the curve in FIG. 1 is represented by the following Formula (1).
Formula (1) E ≧ 15100w ^-0.6797
However, in Formula (1), E represents the tensile elasticity modulus (MPa) of the coated paper in the CD direction, and w represents the content (% by mass) of the release agent contained in the toner.

In the image forming method of the present invention, the toner present on the surface of the coating layer is dissolved and crushed by heat and pressure during fixing, and the release agent eluted from the toner is present at the interface between the toner image and the fixing member. Since it is supplied, releasability is ensured. However, when the coating layer is thin, the release agent eluted from the toner is absorbed by the coated paper, and the heat and pressure energy for dissolving and crushing the toner is sufficient for the toner. In some cases, the mold releasability is lowered as a result.
Therefore, the coating amount per one side of the substrate when forming the coating layer is preferably 5 g / m ² or more, more preferably 6 g / m ² or more in terms of solid content.

Next, the coated paper, toner (developer) and image forming apparatus used in the present invention, and an image forming method using them will be described in more detail.
[Coated paper]
The fiber used for the base material of the coated paper used in the image forming method of the present invention is not particularly limited, but wood pulp fibers used for the base paper of ordinary general coated paper, for example, kraft It is preferable to use pulp fiber, sulfite pulp fiber, semi-chemical pulp fiber, chemiground pulp fiber, groundwood pulp fiber, refiner ground pulp fiber, thermomechanical pulp fiber and the like. Moreover, the fiber which chemically modified the cellulose or hemicellulose in these fibers can also be used as needed.

  Furthermore, cotton pulp fiber, hemp pulp fiber, kenaf pulp fiber, bagasse pulp fiber, viscose rayon fiber, regenerated cellulose fiber, copper ammonia rayon fiber, cellulose acetate fiber, polyvinyl chloride fiber, polyacrylonitrile fiber, polyvinyl alcohol fiber, Polyvinylidene chloride fiber, polyolefin fiber, polyurethane fiber, polyvinyl chloride, polyvinyl alcohol copolymer, fluorocarbon fiber, glass fiber, carbon fiber, alumina fiber, metal fiber, silicon carbide fiber, etc. Or it can be used 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.
Also, high-quality and medium-quality waste paper pulp can be blended. The amount of waste paper pulp is determined according to the purpose of use and purpose. For example, when waste paper pulp is blended from the viewpoint of resource protection, it is 10% by weight or more, preferably 30% by weight or more in the total fiber. Can be blended.

For the base material (base paper) used for the coated paper used in the image forming method of the present invention, a filler is used for improving the coating suitability and adjusting the opacity and whiteness after coating. It is preferable.
Fillers that can be used here are heavy calcium carbonate, light calcium carbonate, kaolin, calcined clay, inorganic fillers such as silicic acids such as pyroferrite, sericite, talc, and titanium dioxide, and urea resins, styrene, etc. It is also possible to blend organic pigments, and thermoplastic resin particles such as polyester and styrene acrylic. These thermoplastic particles are used to bind fibers and improve tensile modulus. . However, the filler is not limited to these.

  Moreover, the compounding quantity of these fillers is not specifically limited, It is desirable to mix | blend 3 to 25 mass%, and it is more desirable to mix | blend 5 to 15 mass%. In particular, when a large amount of inorganic filler is blended, interfiber bonding may be hindered and the tensile elastic modulus may be lowered.

In addition, various chemicals such as a sizing agent can be used for the base material used for the coated paper used in the image forming method of the present invention 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 and 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. As the surface sizing agent, modified cellulose such as oxidized modified starch, enzyme modified starch, polyvinyl alcohol and carboxymethyl cellulose can be used alone or in combination.

  Furthermore, the base material used for the coated paper used in the image forming method of the present invention is sodium chloride, potassium chloride, calcium chloride, sodium sulfate, zinc oxide, titanium dioxide, oxidized for the purpose of adjusting the electrical resistivity of the paper. Inorganic materials such as tin, aluminum oxide, and magnesium oxide, and organic materials such as alkyl phosphate ester acid, alkyl sulfate ester acid, sodium sulfonate salt, and quaternary ammonium salt can be used alone or in combination. .

  Further, a paper strength enhancer can be internally or externally added to the base material used for the coated paper used in the image forming method of the present invention, if necessary. As paper strength enhancers, starch, modified starch, vegetable gum, carboxymethyl cellulose, 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.

For the base material used for the coated paper used in the image forming method of the present invention, in addition to the above-mentioned materials, various auxiliaries blended in ordinary coated paper base paper, such as dyes and pH adjusters, are appropriately used. It doesn't matter.
In the image forming method of the present invention, the method for improving the tensile elastic modulus in the CD direction of the coated paper to be used is not particularly limited, and a known method can be used. For example, the fiber orientation ratio of the substrate is reduced. Is preferred. Desirably, the fiber orientation ratio measured by a fiber orientation meter (for example, SST210 manufactured by Nomura Shoji Co., Ltd.) by an ultrasonic propagation velocity method is preferably in the range of 1.0 to 1.5, and 1.1 to More preferably, it is within the range of 1.35.

  Further, as another method for improving the tensile elastic modulus in the CD direction, it is also preferable to blend the above-described paper strength improver. Moreover, you may mix | blend the material which bridge | crosslinks between s carbodiimide type | system | group and a zirconium carbonate type cellulose fiber as needed. Furthermore, as described above, the tensile elastic modulus in the CD direction can be improved by not filling the base material with an unnecessarily large amount of filler, or by not blending the above-described synthetic fiber more than necessary.

  Next, the coating layer provided on the coated paper used in the image forming method of the present invention will be described. In the coated paper used in the present invention, the coating layer containing the pigment and the adhesive as the main components may be formed on at least one side of the substrate, but the coating layer is formed on both sides of the substrate. It is desirable to do.

  Examples of the pigment contained in the coating layer 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, and barium sulfate. , Zinc oxide, magnesium oxide, magnesium carbonate, amorphous silica, colloidal silica, white carbon, kaolin, calcined kaolin, delaminated clay, aluminosilicate, sericite, bentonite, smectite and other mineral pigments and polystyrene resin Examples thereof include fine particles, urea formaldehyde resin fine particles, fine hollow particles, and other organic pigments, and these can be used alone or in combination.

The adhesive used for the coating layer in the coated paper used in the image forming method of the present invention may be a synthetic adhesive or a natural adhesive, and is not particularly limited.
Synthetic adhesives include, for example, various copolymers such as styrene-butadiene, styrene-acrylic, ethylene-vinyl acetate, butadiene-methyl methacrylate, vinyl acetate-butyl acrylate, polyvinyl alcohol, and maleic anhydride Examples thereof include a copolymer and an acrylic acid-methyl methacrylate copolymer. One or more of these synthetic adhesives can be used, and two or more can be used in combination depending on the purpose. These synthetic adhesives are preferably used in an amount of about 5 to 50% by mass, more preferably about 10 to 30% by mass per 100% by mass of the pigment.

Natural adhesives include oxidized starches, esterified starches, enzyme-modified starches, cold water soluble starches obtained by flash drying them, casein, soy protein, and other commonly known adhesives. Can be mentioned. These natural adhesives are preferably 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-proofing agent, are used suitably as needed.
The coating layer in the coated paper used in the image forming method of the present invention is prepared by mixing the above-mentioned components to prepare a coating composition, which is applied to both surfaces of the base material by an appropriate coating apparatus. Is formed.

The prepared coating composition 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, die slot coater, gravure coater, etc. Is applied to both surfaces of the substrate by on-machine or off-machine. At this time, it may be applied once, but it may be divided into multiple layers to form a single coating layer.
The coating thickness of the coating layer is preferably in the range of 5 g / m ^{2 to} 15 g / m ² in terms of solid content (dry weight) per side of the substrate, and is preferably 5 g / m ^{2 to} 13 g / m ² . it is desirable in the range, it is more desirable that the range of ^{6g / m 2 ~11g / m 2} .

After the application of the coating layer, a smoothing process is appropriately performed. For the smoothing process at this time, a commonly used smoothing device, for example, a super calendar, a machine calendar, a soft nip calender or the like is used, so that the Oken type smoothness is at least 500 seconds or more as described above. It is necessary to finish it.
In the image forming method of the present invention, in order to improve the tensile elastic modulus in the CD direction of the coated paper to be used, the Tg (glass transition temperature) of the synthetic adhesive to be used can be set high, preferably It is 10 degreeC or more and 60 degrees C or less, More preferably, they are 20 degreeC or more and 55 degrees C or less, More preferably, they are 30 degreeC or more and 55 degrees C or less.

The coated paper used in the image forming method of the present invention preferably has a basis weight (JISP-8124) of 50 g / m ² or more and 100 g / m ² or less. When the basis weight is less than 50 g / m ² , even in the image forming method of the present invention, there is a case where wrapping in the fixing step and image defects due to peeling failure are likely to occur.

Furthermore, it is desirable that the coated paper used in the present invention is adjusted so that the air permeability (JTapp INo. 5, Oken air permeability) is 7000 seconds or less, more preferably 5000 seconds or less. When the air permeability exceeds 7000 seconds, moisture (water vapor) in the coated paper is difficult to dissipate due to heating and pressurization in the fixing step, so that the vapor pressure in the coated paper is likely to increase, particularly in a high humidity environment. In some cases, it is difficult to suppress the generation of blisters with coated paper that has been conditioned to a high humidity.
The lower limit of the air permeability is preferably 400 seconds or longer. If the air permeability is less than 400 seconds, the gloss of the coated paper tends to be low, the strength of the coating layer tends to be low, and paper dust may be generated.

  When the coated paper is shipped as a product, the product moisture content immediately after opening is within an appropriate range, specifically preferably 3 to 6.5% by mass, more preferably 4.5 to 5.5% by mass. It is preferable to adjust the water content by a paper machine, a coater dryer, a calendar process, or the like so as to be within the range of the degree. Moreover, it is desirable to wrap using moisture-proof wrapping paper such as polyethylene laminate paper or material such as polypropylene so that moisture absorption and desorption does not occur during storage.

[Toner (and developer)]
Next, as the toner (and developer) that can be used in the image forming method of the present invention, the following can be preferably used.
(toner)
In general, the binder resin component of the toner suitable for use in the image forming method of the present invention includes an amorphous polyester resin, a crystalline polyester resin, a styrene-acrylic resin, an epoxy resin, a polyurethane resin, and the like. There are no particular restrictions. Further, the pigment component of a suitable toner is not particularly limited, and conventionally known pigment components can be used without any problem.

As a manufacturing method of the toner used in the present invention, any manufacturing method such as a pulverization method or a polymerization method may be adopted. However, a resin particle dispersion in which resin particles are dispersed and a colorant in which a colorant is dispersed. The emulsion polymerization aggregation method is preferred in which the dispersion is mixed, the resin particles and the colorant are aggregated to a toner particle size, and the resulting aggregate is heated and fused to a temperature equal to or higher than the glass transition point of the resin. Examples of the emulsion polymerization aggregation method include, but are not limited to, methods disclosed in JP-A-6-250439 and Japanese Patent No. 3141784.
In the following description of the toner constituting material such as the binder resin of the toner used in the present invention, the production of the toner constituting material itself and the use form at the time of toner production are basically wet methods such as an emulsion polymerization aggregation method. Although the description will be made on the premise of the manufacturing method, the toner constituent materials themselves listed below are of course applicable to other manufacturing methods such as a dry manufacturing method.

As specific examples of the binder resin for the toner used in the present invention, known resin materials can be used. For example, styrenes such as styrene, parachlorostyrene, and α-methylstyrene: methyl acrylate, acrylic acid Vinyl such as ethyl, n-propyl acrylate, n-butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate Esters having a group: Vinyl nitriles such as acrylonitrile and methacrylonitrile: Vinyl ethers such as vinyl methyl ether and vinyl isobutyl ether: Vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and vinyl isopropenyl ketone: Ethylene, Examples include homopolymers of monomers such as polyolefins such as propylene and butadiene, copolymers obtained by combining two or more of these, and mixtures thereof, and epoxy resins, polyester resins, and polyurethane resins. , Polyamide resins, cellulose resins, polyether resins, etc., non-vinyl condensation resins, mixtures of these with the vinyl resins, and graft polymers obtained when polymerizing vinyl monomers in the presence of them Is mentioned.
Among these, styrene-alkyl acrylate copolymers and styrene-alkyl methacrylate copolymers are particularly preferable.

In the toner used in the present invention, a dissociative vinyl monomer may be contained together with a monomer constituting the binder resin during the polymerization of the binder resin in order to improve the chargeability with the carrier.
Examples of the dissociable vinyl monomer include acrylic acid, methacrylic acid, maleic acid, cinnamic acid, fumaric acid, vinyl sulfonic acid, ethyleneimine, vinyl pyridine, vinyl amine and other polymer acids and polymer bases. Any of the monomers can be used. Among these, polymer acids are preferred because of the ease of polymer formation reaction, among others, dissociable vinyl monomers having a carboxyl group such as acrylic acid, methacrylic acid, maleic acid, cinnamic acid, and fumaric acid. It is preferable from the viewpoint of controllability of the charge amount. In addition, these dissociative vinyl monomers can be used by being copolymerized at the time of polymerization of the binder resin.

  A chain transfer agent can be used during the polymerization of the binder resin of the toner used in the present invention. Although there is no restriction | limiting in particular as a chain transfer agent, The compound which has a thiol component can be used. Specifically, alkyl mercaptans such as hexyl mercaptan, heptyl mercaptan, octyl mercaptan, nonyl mercaptan, decyl mercaptan, and dodecyl mercaptan are preferred, and in particular, the molecular weight distribution is narrow, so that the storage stability of the toner at high temperature is improved. preferable.

  In addition, a crosslinking agent can be added to the binder resin as necessary. Specific examples of such crosslinking agents include aromatic polyvinyl compounds such as divinylbenzene and divinylnaphthalene; divinyl phthalate, divinyl isophthalate, divinyl terephthalate, divinyl homophthalate, divinyl trimesate / trivinyl, naphthalene dicarboxylate Polyvinyl esters of aromatic polyvalent carboxylic acids such as divinyl acid and divinyl biphenyl carboxylate; Divinyl esters of nitrogen-containing aromatic compounds such as divinyl pyridinedicarboxylate; Vinyl pyromuccinate, vinyl furancarboxylate, pyrrole-2- Vinyl esters of unsaturated heterocyclic compounds such as vinyl carboxylate and vinyl thiophenecarboxylate; butanediol methacrylate, hexanediol acrylate, octanediol methacrylate, decanediol acrylate (Meth) acrylic acid esters of linear polyhydric alcohols such as dodecanediol methacrylate; branches such as neopentylglycol dimethacrylate and 2-hydroxy-1,3-diaacryloxypropane; ) Acrylic acid esters; Polyethylene glycol di (meth) acrylate, Polypropylene polyethylene glycol di (meth) acrylates; Divinyl succinate, divinyl fumarate, vinyl / divinyl maleate, divinyl diglycolate, vinyl / divinyl itaconate, acetone Divinyl dicarboxylate, divinyl glutarate, divinyl 3,3′-thiodipropionate, trans-aconite divinyl / trivinyl, divinyl adipate, divinyl pimelate, divinyl suberate, dibi azelate Le, sebacate, divinyl dodecanedioate divinyl, the polyvinyl esters of polycarboxylic acids such as oxalic acid, divinyl; and the like.

These cross-linking agents listed above may be used alone or in combination of two or more. Among the crosslinking agents, more preferable crosslinking agents include (meth) acrylic acid esters of linear polyhydric alcohols such as butanediol methacrylate, hexanediol acrylate, octanediol methacrylate, decanediol acrylate, and dodecanediol methacrylate; Branches such as neopentyl glycol dimethacrylate, 2-hydroxy-1,3-diaacryloxypropane, (meth) acrylic acid esters of substituted polyhydric alcohols; polyethylene glycol di (meth) acrylate, polypropylene polyethylene glycol di (meth) ) Acrylates and the like.
The content of the crosslinking agent is preferably in the range of 0.05 to 5% by mass, more preferably in the range of 0.1 to 1.0% by mass, based on the total amount of polymerizable monomers that are the raw materials for the binder resin. .

The toner binder resin used in the present invention can also be produced by radical polymerization of a polymerizable monomer.
There is no restriction | limiting in particular as an initiator for radical polymerization used here. Specifically, hydrogen peroxide, acetyl peroxide, cumyl peroxide, tert-butyl peroxide, propionyl peroxide, benzoyl peroxide, chlorobenzoyl peroxide, dichlorobenzoyl peroxide, bromomethylbenzoyl peroxide, lauroyl peroxide Ammonium persulfate, sodium persulfate, potassium persulfate, diisopropyl peroxycarbonate, tetralin hydroperoxide, 1-phenyl-2-methylpropyl-1-hydroperoxide, tert-butyl hydroperoxide pertriphenyl acetate, tert-butyl formate, Peroxides such as tert-butyl peracetate, tert-butyl perbenzoate, tert-butyl perphenylacetate, tert-butyl permethoxyacetate, tert-butyl perN- (3-toluyl) carbamate, 2,2 '-Azobispro Bread, 2,2′-dichloro-2,2′-azobispropane, 1,1′-azo (methylethyl) diacetate, 2,2′-azobis (2-amidinopropane) hydrochloride, 2,2 ′ -Azobis (2-amidinopropane) nitrate, 2,2'-azobisisobutane, 2,2'-azobisisobutyramide, 2,2'-azobisisobutyronitrile, 2,2'-azobis-2- Methyl methylpropionate, 2,2′-dichloro-2,2′-azobisbutane, 2,2′-azobis-2-methylbutyronitrile, dimethyl 2,2′-azobisisobutyrate, 1,1′-azobis (1 -Methylbutyronitrile-3-sodium sulfonate), 2- (4-methylphenylazo) -2-methylmalonodinitrile, 4,4'-azobis-4-cyanovaleric acid, 3,5-dihydroxymethylphenyl Zo-2-methylmalonodinitrile, 2- (4-bromophenylazo) -2-allylmalonodinitrile, 2,2'-azobis-2-methylvaleronitrile, 4,4'-azobis-4-cyanoyoshi Dimethyl herbate, 2,2′-azobis-2,4-dimethylvaleronitrile, 1,1′-azobiscyclohexanenitrile, 2,2′-azobis-2-propylbutyronitrile, 1,1′-azobis-1 -Chlorophenylethane, 1,1'-azobis-1-cyclohexanecarbonitrile, 1,1'-azobis-1-cycloheptanenitrile, 1,1'-azobis-1-phenylethane, 1,1'-azobiscumene, 4-Nitrophenylazobenzylcyanoacetate, phenylazodiphenylmethane, phenylazotriphenylmethane, 4-nitrophenylazotrif Nylmethane, 1,1′-azobis-1,2-diphenylethane, poly (bisphenol A-4,4′-azobis-4-cyanopentanoate), poly (tetraethylene glycol-2,2′-azobisiso) Azo compounds such as butyrate), 1,4-bis (pentaethylene) -2-tetrazene, 1,4-dimethoxycarbonyl-1,4-diphenyl-2-tetrazene and the like.

Further, known colorants can be used as the colorant added to the toner used in the present invention.
Examples of pigments include carbon black, copper oxide, black titanium oxide, black iron hydroxide, manganese dioxide, aniline black, activated carbon, magnetic powder such as nonmagnetic ferrite, magnetic ferrite, and magnetite, aniline blue, calcoil blue, and chromium. Yellow, ultramarine blue, dupont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, rose bengal, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 57: 1, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 17, C.I. I. Pigment blue 15: 1, C.I. I. Pigment Blue 15: 3 can be exemplified as a representative one.

As the colorant, a dye can be used. Examples of the dye that can be used include various dyes such as basic, acidic, dispersed, and direct dyes, such as nigrosine. Moreover, these can be used individually or in mixture, and also in the state of a solid solution.
These colorants are dispersed by a known method, and for example, a rotary shear type homogenizer, a media type dispersing machine such as a ball mill, a sand mill, or an attritor, a high-pressure opposed collision type dispersing machine, or the like is preferably used.
Since the colorant is a surfactant having polarity and is dispersed in the aqueous system by the homogenizer, the colorant is selected from the viewpoint of dispersibility in the toner. The added amount of the colorant can be 3 to 50 parts by weight with respect to 100 parts by weight of the binder resin.

  Examples of release agents added to the toner used in the present invention include low molecular weight polyolefins such as polyethylene, polypropylene, and polybutene: silicones having a softening point upon heating: oleic amide, erucic amide, ricinoleic amide, stearic acid Fatty acid amides such as amides: plant waxes such as carnauba wax, rice wax, candelilla wax, tree wax, jojoba oil, etc .: animal waxes such as beeswax: montan wax, ozokerite, ceresin, paraffin wax, Examples thereof include minerals such as microcrystalline wax and Fischer-Tropsch wax or petroleum waxes, and modified products thereof.

  The release agent is dispersed in water together with ionic surfactants, polymer electrolytes such as polymer acids and polymer bases, and then micronized with a homogenizer or pressure discharge type disperser that can be heated to the melting point or higher and subjected to strong shearing. A release agent dispersion liquid containing release agent particles having a particle diameter of 1 μm or less can be prepared.

  In the production of the toner in the present invention, for example, stabilization at the time of dispersion when using the suspension polymerization method, resin particle dispersion, colorant dispersion, and release agent dispersion when using the emulsion polymerization aggregation method A surfactant can be used for the purpose of stabilizing the dispersion of the composition.

  Examples of the surfactant include anionic surfactants such as sulfate, sulfonate, phosphate, and soap; cationic surfactants such as amine salt type and quaternary ammonium salt type; polyethylene glycol And nonionic surfactants such as polyphenols, alkylphenol ethylene oxide adducts, and polyhydric alcohols. Among these, an ionic surfactant is preferable, and an anionic surfactant and a cationic surfactant are more preferable.

In the toner possessed by the present invention, an anionic surfactant generally has a strong dispersing power and is excellent in the dispersion of resin particles and colorants. Therefore, as a surfactant for dispersing a release agent. It is advantageous to use an anionic surfactant.
The nonionic surfactant is preferably used in combination with the anionic surfactant or the cationic surfactant. The said surfactant may be used individually by 1 type, and may be used in combination of 2 or more type.

  Specific examples of anionic surfactants include fatty acid soaps such as potassium laurate, sodium oleate, and castor oil sodium; sulfates such as octyl sulfate, lauryl sulfate, lauryl ether sulfate, and nonyl phenyl ether sulfate; lauryl sulfonate , Sodium alkylnaphthalene sulfonate such as dodecylbenzene sulfonate, triisopropyl naphthalene sulfonate, dibutyl naphthalene sulfonate; sulfone such as naphthalene sulfonate formalin condensate, monooctyl sulfosuccinate, dioctyl sulfosuccinate, lauric acid amide sulfonate, oleic acid amide sulfonate Acid salts; lauryl phosphate, isopropyl phosphate, nonylphenyl ether Phosphoric acid esters such as Sufeto; dialkyl sulfosuccinate salts such as sodium dioctyl sulfosuccinate; sulfosuccinate salts such as sulfosuccinate lauryl disodium; and the like.

  Specific examples of the cationic surfactant include laurylamine hydrochloride, stearylamine hydrochloride, oleylamine acetate, stearylamine acetate, stearylaminopropylamine acetate, and other amine salts; lauryltrimethylammonium chloride, dilauryldimethylammonium Chloride, distearyldimethylammonium chloride, distearyldimethylammonium chloride, lauryldihydroxyethylmethylammonium chloride, oleylbispolyoxyethylenemethylammonium chloride, lauroylaminopropyldimethylethylammonium ethosulphate, lauroylaminopropyldimethylhydroxyethylammonium perchlorate, alkylbenzene Trimethylammonium chloride, Quaternary ammonium salts such as quilts trimethyl ammonium chloride; and the like.

  Specific examples of the nonionic surfactant include alkyl ethers such as polyoxyethylene octyl ether, polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether; polyoxyethylene octyl phenyl ether, polyoxy Alkyl phenyl ethers such as ethylene nonyl phenyl ether; alkyl esters such as polyoxyethylene laurate, polyoxyethylene stearate, polyoxyethylene oleate; polyoxyethylene lauryl amino ether, polyoxyethylene stearyl amino ether, polyoxyethylene Alkylamines such as oleyl amino ether, polyoxyethylene soybean amino ether, polyoxyethylene beef tallow amino ether; Alkyl amides such as ethylene lauric acid amide, polyoxyethylene stearic acid amide, polyoxyethylene oleic acid amide; vegetable oil ethers such as polyoxyethylene castor oil ether and polyoxyethylene rapeseed oil ether; lauric acid diethanolamide, stearic acid Alkanolamides such as diethanolamide and oleic acid diethanolamide; sorbitan ester ethers such as polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate And so on.

The content of the surfactant in each dispersion is generally a small amount, specifically in the range of about 0.01 to 10% by mass, more preferably 0.05 to 5% by mass. It is a range, More preferably, it is the range of about 0.1-2 mass%.
When the content is less than 0.01% by mass, each dispersion such as a resin particle dispersion, a colorant dispersion, and a release agent dispersion becomes unstable, so that aggregation occurs, and each particle during aggregation There are problems such as the release of specific particles due to the difference in stability between them, and when the amount exceeds 10% by mass, the particle size distribution of the particles becomes wide, and the control of the particle size becomes difficult. It may not be preferable for the reason. In general, a suspension-polymerized toner dispersion having a large particle size is stable even when a small amount of a surfactant is used.

In addition, as a dispersion stabilizer used in the suspension polymerization method or the like, a slightly water-soluble and hydrophilic inorganic fine powder can be used. Examples of the inorganic fine powder that can be used include silica, alumina, titania, calcium carbonate, magnesium carbonate, tricalcium phosphate (hydroxyapatite), clay, diatomaceous earth, bentonite and the like. Among these, calcium carbonate, tricalcium phosphate, and the like are preferable from the viewpoints of easy particle size formation and easy removal.
Also, a room temperature solid aqueous polymer or the like can be used. Specifically, cellulose compounds such as carboxymethyl cellulose and hydroxypropyl cellulose, polyvinyl alcohol, gelatin, starch, gum arabic and the like can be used.

In addition, a charge control agent may be added to the toner used in the present invention as necessary.
Known charge control agents can be used, but azo metal complex compounds, metal complex compounds of salicylic acid, and resin-type charge control agents containing polar groups can be used.
When the toner is manufactured by a wet manufacturing method, it is preferable to use a material that is difficult to dissolve in water in terms of controlling ionic strength and reducing wastewater contamination. The toner in the present invention may be either a magnetic toner containing a magnetic material or a non-magnetic toner containing no magnetic material.

  Examples of polymerizable UV-stable monomers include 4- (meth) acryloyloxy-2,2,6,6-tetramethylpiperidine, 4- (meth) acryloylamino-2,2,6,6-tetrapiperidine 4- (meth) acryloyloxy-1,2,2,6,6-pentamethylpiperidine, 4- (meth) acryloylamino-1,2,2,6,6-pentamethylpiperidine, 4-cyano-4- Piperidine compounds such as (meth) acryloylamino-2,2,6,6-tetramethylpiperidine, 1- (meth) acryloylru 4- (meth) acryloylamino-2,2,6,6-tetramethylpiperidine are effective. Is. These can be used alone or in combination of two or more.

  It is desirable to add these release agents in the range of 5 to 25% by mass with respect to the total mass of the toner constituting solids, in order to ensure the releasability of the fixed image in the oilless fixing system, and more preferably 7%. It is preferable to add in the range of ˜20% by mass. The particle size of the obtained release agent particle dispersion can be measured, for example, with a laser diffraction particle size distribution analyzer (LA-700, manufactured by Horiba, Ltd.).

In addition, the toner used in the image forming method of the present invention is dried in the same manner as a normal toner for the purpose of imparting fluidity and improving cleaning properties, and then inorganic fine particles such as silica, alumina, titania, calcium carbonate, vinyl resins, External additives such as resin fine particles such as polyester and silicone can be added to the toner particle surface while being sheared in a dry state.
When these external additives are adhered to the toner surface in water, examples of inorganic fine particles include silica, alumina, titania, calcium carbonate, magnesium carbonate, tricalcium phosphate, etc. Everything used can be used by dispersing using an ionic surfactant, polymer acid, or polymer base.

  As described above, the volume average particle diameter of the toner used in the present invention needs to be 5 μm or less, preferably 4.5 μm or less, and more preferably 4 μm or less. Moreover, as a lower limit, it is preferable that it is 2 micrometers or more, and it is more preferable that it is 2.5 micrometers or more. 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 lowered. On the other hand, when the thickness exceeds 5 μm, as described above, an image defect occurs due to wrapping around the fixing device or peeling failure from the fixing device. Further, the resolution of the image may be deteriorated.

Here, the volume average particle diameter of the toner means a particle diameter (D _50v ) at which the cumulative volume becomes 50% from the small diameter side, for example, Coulter Counter TA-II (manufactured by Beckman-Coulter), Multisizer II (Beckman). -It can measure using measuring instruments, such as -Coulter company.
Further, the particle size distribution of the toner used in the present invention is preferably 1.28 or less, and more preferably 1.25 or less, as a volume average particle size distribution index GSDv. In particular, a toner having a sharp particle size distribution can be obtained by producing by an emulsion aggregation method. If GSDv exceeds 1.28, the sharpness and resolution of the image may be degraded.
Here, the volume average particle size distribution index GSDv of the toner is a ratio of the volume average particle diameter D _{16v at which} the cumulative volume is 16% to the volume average particle diameter D _84v at which the cumulative volume is 84% from the small diameter side (D _84v / D _16v ) refers to the square root, and can be measured using an apparatus similar to the apparatus used for measuring the volume average particle diameter.

When the volume average particle diameter of the toner to be measured is less than 2 μm, it can be measured using a laser diffraction particle size distribution measuring device (LA-700: manufactured by Horiba, Ltd.) instead of the above-described measuring device. .
As a measurement method in this case, a dispersion liquid sample in which toner particles are dispersed in a solution is adjusted to have a solid content of about 2 g, and ion-exchanged water is added thereto to make about 40 ml. This is put into the cell until an appropriate concentration is reached, waits for about 2 minutes, and is measured when the concentration in the cell becomes almost stable. The obtained volume average particle diameter for each channel is accumulated from the smaller volume average particle diameter, and the place where the accumulation reaches 50% can be obtained as the volume average particle diameter.

As the particle shape of the toner used in the present invention, the average value of the shape factor SF1 defined by the following formula (2) is preferably in the range of 100 to 140, and more preferably in the range of 110 to 135. .
Formula (2) SF1 = ML ² × 100 × π / 4A
(In the formula (2), ML represents the maximum length (μm ² ) of the toner particle diameter, and A represents the projected area (μm ² ) of the toner particle)

The shape factor SF1 is used as a factor expressing the shape of the toner and the like, and when the toner particles are observed with an optical microscope or the like, the area, length, shape, etc. of the toner particles can be quantitatively analyzed with high accuracy. Can be measured by, for example, an image analyzer (Image Analyzer LUZEX III manufactured by NIRECO).
In the present invention, the shape factor SF1 is a value obtained by averaging the values of the shape factor SF1 obtained by image analysis of 200 toner particles to be measured.

  As apparent from the above formula (2), the shape factor SF1 is obtained by multiplying the value obtained by squaring the maximum length of the toner particle diameter by the square of the toner particle area by π / 4, and further multiplying by 100. As the toner particle shape is closer to a sphere, the value is closer to 100, and conversely, the longer the toner particle is, the larger the value is. That is, the difference between the maximum diameter and the minimum diameter of the toner, that is, the shape factor SF1 is an index representing distortion. If it is a perfect sphere, the shape factor SF1 = 100.

(Developer)
The developer that can be used in the image forming method of the present invention is not particularly limited as long as it contains at least a toner having a volume average particle diameter of 5 μm or less, and can have an appropriate component composition depending on the purpose.
The developer used in the present invention can be selected from a one-component developer composed of toner alone or a two-component developer using a combination of toner and carrier.
The carrier used in the two-component developer is not particularly limited. For example, known carriers such as resin-coated carriers disclosed in JP-A Nos. 62-39879 and 56-11461 can be used. Can be used. The mixing ratio of the toner and the carrier in the two-component developer is not particularly limited and can be appropriately selected depending on the purpose.

[Image forming method]
Next, details of each step of the image forming method of the present invention, and an image forming apparatus and a fixing device used therefor will be described in more detail.
The image forming method of the present invention is a known electrophotographic method as long as it uses a combination of the above-mentioned coated paper having a surface roughness of 500 seconds or more and a toner having a volume average particle diameter of 5 μm or less. An image forming process using a method can be applied, but at least a fixing process for forming an image by fixing an unfixed toner image formed on the surface of the coated paper provided with the coating layer by heating and pressing. In addition to this, for example, a latent image forming step of forming a latent image on the surface of the latent image carrier, the latent image is developed using a developer, and an unfixed toner image is formed on the surface of the latent image carrier. It is more preferable to include a developing step for forming and a transferring step for transferring the developed unfixed toner image to a transfer target (coated paper having a coated layer surface having a Wangken smoothness of 500 seconds or more).

Further, an unfixed color toner image is formed by superimposing and transferring the unfixed toner image of each color formed on the surface of the latent image carrier onto an intermediate transfer member such as a belt. A full-color image can be formed by adopting an intermediate transfer process that batch-transfers to the coated paper surface.
Further, in the present invention, since a coating paper having a surface roughness of 500 seconds or more and a toner having a volume average particle diameter of 5 μm or less are used in combination, various conventionally known fixing devices are used. However, regardless of the type of the fixing device, it is possible to prevent the occurrence of image defects due to winding and peeling defects in the fixing process.
Examples of image forming apparatuses applicable in the image forming method of the present invention will be given below.

<Image forming apparatus I>
FIG. 2 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. 2 includes a photoconductor (latent image carrier) 11 that rotates in the direction of arrow A, and around the photoconductor 11 is a roll-type charger 12, an exposure device 13, cyan, magenta, and yellow. Developer 14a, 14b, 14c and 14d each containing developer of four colors of black and black, belt-like intermediate transfer member 15, cleaner 16, and light neutralizer 17 are arranged in this order. Has been. The intermediate transfer member 15 is stretched by support shaft rolls 18a, 18b, and 18c. The spindle roll 18 a forms a pressure contact portion (primary transfer portion) with the photoreceptor 11 via the intermediate transfer member 15. The spindle roll 18 c is pressed against the transfer roll 19 through the intermediate transfer body 15. Between the pressure contact portion (secondary transfer portion) between the intermediate transfer body 15 and the transfer roll 19, the transfer body 7 transported by transport means (not shown) can be inserted in the arrow B direction. A fixing device including a heat roll 1 and a pressure-bonding roll 2 disposed so as to be opposed to this is disposed on the conveyance path of the transfer object 7 of the pressure contact portion (secondary transfer portion). The transferred material 7 that has passed can be inserted through the nip formed between the pair of rolls.

In the image forming apparatus shown in FIG. 2, an image is formed as follows.
First, the photosensitive member 11 charged by the charger 12 is exposed by the exposure device 13 based on the image information of four colors of cyan, magenta, yellow, and black, and a latent image of each color is formed on the surface of the photosensitive member 11. Let The latent image on the surface of the photoconductor 11 is developed by a developing device corresponding to each of the developing devices 14a, 14b, 14c, and 14d built in the developing device 14, and an unfixed toner image is formed. The developed unfixed toner image is electrostatically transferred to the outer peripheral surface of the belt-shaped intermediate transfer body 15 at a portion facing the support shaft roll 18a.

The toner remaining on the surface of the photoconductor 11 after the unfixed toner image on the surface of the photoconductor 11 is transferred to the transfer target (coated paper) 7 is removed by the cleaner 16. Further, the residual charge remaining on the surface of the photoconductor 11 is neutralized by the light neutralizer 17. The photoreceptor 11 is prepared for the next image formation.
This operation is performed for each of four colors of cyan, magenta, yellow, and black, and the toner images are sequentially laminated on the outer peripheral surface of the intermediate transfer member 15, so that a full-color unfixed toner image is formed on the outer peripheral surface of the intermediate transfer member 15. The

The full-color unfixed toner image formed on the outer peripheral surface of the intermediate transfer member 15 is moved by the support roller 18 c and the transfer roller 19 through the intermediate transfer member 15 as the intermediate transfer member 15 advances in the arrow P direction. Move to the part (secondary transfer portion) that is in pressure contact. When the unfixed toner image on the outer peripheral surface of the intermediate transfer body 15 passes through the nip portion, the unfixed toner image is transferred to the surface of the transfer medium 7 that is inserted therethrough and proceeds in the arrow B direction.
The unfixed toner image on the surface of the transfer medium 7 obtained in this way is fixed by a fixing device located on the downstream side in the transport direction of the secondary transfer portion. The fixing device shown in FIG. 2 includes a pair of rolls whose outer peripheral surfaces are opposed to each other to form a nip portion, and the unfixed toner is formed by applying heat and pressure when the transfer target passes through the nip portion. Any fixing device that fixes an image and has a function of fixing an unfixed toner image by heat and pressure can be used without particular limitation.

  Examples of the fixing device used in the image forming method of the present invention include a contact-type heat fixing device. For example, a heating roll in which a rubber elastic layer is formed on the outer periphery of a core metal and a surface layer of a fixing member is further provided as necessary. And a hot roll type fixing device comprising a pressure roll having a rubber elastic layer formed on the outer periphery of the core metal and optionally having a fixing member surface layer, and a combination of the roll and the roll, Examples thereof include a combination with a belt and a fixing device in place of the combination of a belt and a belt.

For the base material (core) of the fixing member, a material having excellent heat resistance, strong strength against deformation, and good thermal conductivity is selected. In the case of a roll type fixing device, for example, aluminum, iron, copper, etc. In the case of a belt-type fixing device, for example, a polyimide film, a stainless steel belt, or the like is selected. A rubber elastic layer usually made of silicone rubber, fluororubber or the like is provided on the surface of the base material in the roll type fixing device.
The base material and rubber elastic layer of the fixing member may contain various additives depending on the purpose, for example, carbon black or metal oxide for the purpose of improving wear resistance, resistance value control, etc. Ceramic particles such as SIC may be contained.
The following are examples of some preferred fixing devices.

<Fixing device I>
First, an example of a heat roll type fixing device (fixing device I) will be described in detail. This fixing device includes a pair of rolls whose outer peripheral surfaces are in contact with each other to form a nip portion. In this fixing device, an object to be transferred on which an unfixed toner image is formed is transferred to the nip portion. Fixing is carried out by inserting the film into a sheet and applying heat and pressure.
FIG. 3 is a schematic diagram showing an example of such a heat roll type fixing device, which is employed in the image forming apparatus shown in FIG.
The fixing device shown in FIG. 3 mainly includes a heat roll 1 having a roll shape and a pressure-bonding roll 2 disposed so as to face the roll. The heat roll 1 is provided with a heating source 3 for heating it inside (inside the core 8), an elastic layer 5 is formed on the outer periphery of the core 8, and the surface of the heat roll 1 is formed on the outer periphery. The fixing member surface layer 4 is formed. The configuration of the pressure roll 2 is not particularly limited as long as it is in a roll shape, but may include a heat source 3 ′ inside or an elastic layer 5 ′ that forms an outer peripheral surface.

When the transfer body 7 having the unfixed toner image 6 formed on the surface thereof is inserted into the nip portion between the pressure roll 2 and the heat roll 1 as it advances in the direction of the arrow B, The unfixed toner image is fixed by heating and pressing.
The fixing device shown in FIG. 3 further includes a cleaning member (not shown) for removing toner adhering to the surface of the heat roll 1 and a nail (finger) for peeling the transfer object 7 from the heat roll 1 as necessary. , Not shown) or the like. The heating source 3 in the fixing device shown in FIG. 3 is controlled by a temperature control device (not shown) so that the surface temperature of the heat roll 1 is constant.

  The heat roll 1 and / or the pressure-bonding roll 2 are preferably provided with elastic layers 5 and 5 ′ having a single layer or a laminated structure. For the elastic layers 5 and 5 ′, heat-resistant rubber such as silicone rubber or fluorine rubber is used, and the rubber hardness (JIS-A) is preferably 60 or less. When the fixing member has the elastic layers 5 and 5 ′, the fixing member is deformed following the unevenness of the unfixed toner image 6 on the transfer body 7, and the smoothness of the image surface after fixing can be improved. This is advantageous.

  The thickness of the elastic layers 5 and 5 ′ is preferably in the range of 0.1 to 3 mm, and more preferably in the range of 0.5 to 2 mm. If the thickness of the elastic layers 5 and 5 ′ exceeds 3 mm and is too thick, the heat capacity of the fixing member increases, and it takes a long time to heat the fixing member to a desired temperature, and energy consumption increases. It is not preferable. On the other hand, if the thickness is less than 0.1 mm, the deformation on the surface of the fixing member cannot follow the unevenness of the unfixed toner image, resulting in unevenness of melting, and distortion of the elastic layer effective for peeling. Is not preferred in that it is difficult to obtain.

<Fixing device II>
Next, an example of the belt-roll nip type fixing device (fixing device II) will be described in detail. This fixing device is in contact with the inner peripheral surface of the endless belt so as to press the outer peripheral surface of the endless belt and the elastic layer, and the endless belt forming an nip portion with the outer peripheral surfaces facing each other. In this fixing device, fixing is performed by inserting a transfer body having an unfixed toner image formed on the surface thereof through a nip portion and applying heat and pressure.

FIG. 4 is a schematic diagram showing an example of such a belt-roll nip type fixing device.
The fixing device shown in FIG. 4 includes a heat fixing roll 21 with a built-in heat source, an endless belt 25 that is stretched between three support rolls 22, 23, and 24 and pressed against the heat fixing roll 21. A main portion is configured by the pressure applying member 31 that is in contact with the inner peripheral surface side and presses the endless belt 25 along the surface of the heat fixing roll 21.

The configuration of the fixing device shown in FIG. 4 will be described below with specific members and dimensions. Of course, the specific configuration of the fixing device shown in FIG. 4 is not limited to the following description.
The heat fixing roll 21 has a cylindrical core 32 inside, and is driven to rotate in the direction of arrow C by a motor 38. First, the core 32 is made of aluminum having an outer diameter of 47 mm, an inner diameter of 42 mm, and a length of 350 mm. The surface of the core 32 is directly coated with an HTV silicone rubber having a hardness of 45 ° (JIS-A) as a base layer 27a with a thickness of 2 mm, and further, an RTV silicone rubber with a thickness of 50 μm as a topcoat layer 27b on the outer peripheral surface thereof. Dip coated. A covering layer 27 is formed by these two layers, and the outer peripheral surface of the covering layer 27 is finished in a surface state close to a mirror surface.

  The hardness of the rubber of the underlayer 27a is a result of measurement by adding a load of 9.8 N (1,000 gf) according to JIS-K6301 using a spring type A type hardness tester manufactured by Teclock. The core 32 can be made of a metal having a high thermal conductivity even if it is not aluminum, and the cover layer 27 can be made of other materials as long as it is an elastic body having high heat resistance. .

  Inside the core 32, a halogen lamp 35 having an output of 850 W is disposed as a heating source. A temperature sensor 30 is disposed on the surface of the heat fixing roll 21 and measures the temperature of the surface of the heat fixing roll 21. Then, the halogen lamp 35 is feedback-controlled by a temperature controller (not shown) based on a measurement signal from the temperature sensor 30, so that the surface of the heat fixing roll 21 is adjusted to 150 ° C.

  The pressure applying member 31 is formed by laminating an elastic layer 31b and a low friction layer 31c on the surface of the base plate 31a, and is pressed against the heat fixing roll 21 by a compression coil spring 26 disposed on the base plate 31a side. Has been. The base plate 31a is made of stainless steel having a width (traveling direction of the endless belt 25) of 20 mm, a length (perpendicular to the traveling direction of the endless belt 25) of 320 mm, and a thickness of 5 mm. The elastic layer 31b is made of a silicone sponge (silicone rubber foam) having a rubber hardness of 23 ° and a thickness of 5 mm.

  Here, the rubber hardness is a result obtained by adding a load of 2.94 N (300 gf) using an Asker C type sponge rubber hardness meter manufactured by Kobunshi Kagaku. Further, as the low friction layer 31c, “FGF-400-4” (trade name) manufactured by Chuko Kasei Co., Ltd., which is a glass fiber sheet impregnated with polytetrafluoroethylene, is used.

  Since the elastic layer 31 b is provided here, the contact surface of the low friction layer 31 c in contact with the endless belt 25 can be aligned with the outer peripheral surface of the heat fixing roll 21. That is, if the pressure applying member 31 is pressed toward the heat fixing roll 21 with a load of a certain level or more, the elastic layer 31 b is deformed and the contact surface of the low friction layer 31 c is pressed along the outer peripheral surface of the heat fixing roll 21. It is designed to be deformed. Therefore, when the pressure applying member 31 is pressed against the heat fixing roll 21 by the compression coil spring 26, the endless belt 25 is pressed against the heat fixing roll 21 without a gap, and a nip portion is formed.

The surface of the low friction layer 31c is coated with dimethyl silicone oil (trade name “KF-96” manufactured by Shin-Etsu Chemical Co., Ltd.) having a viscosity of 1000 mm ² / s (1000 cSt). The friction coefficient with the pressure applying member 31 is reduced. In a state where dimethyl silicone oil is applied, the friction coefficient μ2 between the pressure applying member 31 and the endless belt 25 is smaller than the friction coefficient μ1 between the endless belt 25 and the heat fixing roll 21 ( μ1> μ2). Thus, by setting the friction coefficients on both surfaces of the endless belt 25, the endless belt 25 is driven as the heating and fixing roll 21 rotates and travels while sliding on the pressure applying member 31.

  The endless belt 25 is formed of a polyimide film with a thickness of 75 μm, a width of 300 mm, and a circumferential length of 188 mm. The endless belt 25 is wound with a tension of about 78.4 N (8 kgf) around support rolls 22, 23, and 24 that are arranged at positions away from the heat fixing roll 21. The support rolls 22, 23, and 24 are made of stainless steel, and their diameters are 18 mm, 18 mm, and 23 mm, respectively.

The endless belt 25 is pressed against the heat fixing roll 21 without a gap by the pressure applying member 31 being pressed toward the heat fixing roll 21. At this time, the contact pressure of the pressure applying member 31 is set to about 5.5 × 10 ⁴ Pa (0.56 kgf / cm ² ). The heat fixing roll 21 is rotated in the direction of the arrow C by the motor 38 at a peripheral speed V = 220 mm / sec, and the endless belt 25 is driven to rotate at a speed of 220 mm / sec by this rotation.

Next, the operation of the fixing device shown in FIG. 4 will be described. In this fixing device, at the time of fixing, the transfer body 37 on which the unfixed toner image 36 is formed is transferred from the right side in FIG. 4 (the side on which the support roller 24 of the pressure applying member 31 is provided) by a conveying means (not shown). Then, the nip portion formed between the endless belt 25 and the heat fixing roll 21 is inserted and conveyed to the left side in FIG. 4 (the side where the support roll 22 of the pressure applying member 31 is provided).
Here, the fixing of the unfixed toner image 36 onto the surface of the transfer target 37 is performed when the transfer target 37 is inserted through the nip portion, and the heating fixing roll 21 heated by the pressure applied to the nip portion and the halogen lamp 35. By heating with.

<Fixing device III>
Next, another example of the belt-roll nip type fixing device (fixing device III) will be described in detail. The fixing device includes a pair of endless belts that form opposing contact regions in which the outer peripheral surfaces of each other are opposed to each other along the rotational direction, and the pair of endless belts that are located upstream of the opposing contact region in the rotational direction. It has a configuration including a pair of rolls that press the peripheral surface to form a nip portion.
In this fixing device, a transfer material having an unfixed toner image formed on the surface is inserted into the nip portion, heated and pressurized, and then conveyed to the most downstream side in the rotation direction of the opposing contact region while being sandwiched between a pair of endless belts. Fixing is performed by forcibly cooling while passing through the opposed contact area and peeling from the pair of endless belts.

FIG. 5 is a schematic diagram showing an example of such a belt-roll nip type fixing device.
In the fixing device shown in FIG. 5, a pair of endless belts 43 and 45 (fixing belt 43 and pressure belt 45) stretched by a plurality of support rolls form an opposing contact region in which the opposing contact is made along the rotational direction. A nip portion is formed by a pair of pressure rolls 41 and 42 that press the inner peripheral surfaces of the pair of endless belts 43 and 45 located on the upstream side in the rotation direction of the facing contact region. In addition, the said nip part means the contact part which can implement | achieve the heating and pressurization conditions suitable for fixing among opposing contact areas. Further, in a region other than the nip portion of the opposing contact region, the state in which the fixing belt 43 and the pressure belt 45 are in contact with each other is maintained by the cooling plate 52 disposed so as to press the inner peripheral surface of the fixing belt 43. Yes.

  On the upstream side of the nip portion of the fixing belt 43 in the rotation direction indicated by an arrow E in the figure, first to third heating portions that heat the fixing belt 43 are upstream along the fixing belt 43 from the nip portion in the rotation direction. These three heating portions can provide heating necessary for fixing at the nip portion.

  The first heating unit includes an aluminum heating plate 51 disposed so as to contact the inner peripheral surface of the fixing belt 43. The heating plate 51 uses a cooling plate 52 connected via a heat pipe 53 as a heating source. That is, the remaining heat of the fixing belt 43 or the like that has passed through the nip is absorbed by the cooling plate 52 and transferred to the heating plate 51 through the heat pipe 53, whereby the fixing belt 43 is heated by the heating plate 51. Is done.

The second heating unit is composed of an aluminum heating roll 48 that abuts against the inner peripheral surface of the fixing belt 43. A heater 55a is arranged inside the heating roll 48, and the temperature is controlled by temperature control means (not shown) based on the detection data of the temperature sensor 44a arranged to sense the surface temperature of the heating roll 48. Yes.
The third heating unit is configured by an aluminum heating roll 49 that contacts the outer peripheral surface of the fixing belt 43. A heater 55b is arranged inside the heating roll 49, and the temperature is controlled by temperature control means (not shown) based on the detection data of the temperature sensor 44b arranged to sense the surface temperature of the heating roll 49. Yes.

The fixing belt 43 is sequentially preheated by the first heating unit by the rotation in the direction of arrow E in the drawing, heated from the inner peripheral surface side by the second heating unit, and heated from the outer peripheral surface side by the third heating unit, and fixed. The nip is reached while being heated to a temperature required for the operation. A temperature sensor 44c for detecting the surface temperature of the fixing belt 43 is disposed immediately before the nip portion. Based on the detected data, a control unit (not shown) controls the second heating unit and / or the third temperature sensor. The heating condition of the heating unit is feedback controlled.

At the time of fixing, the transfer target 47 on which the unfixed toner image is formed on the surface by a conveyance unit (not shown) is conveyed to the upstream side in the rotation direction of the opposed contact area, and the opposed contact area is sandwiched between a pair of endless belts. As it is inserted, the sheet passes through the downstream side in the rotation direction of the opposing contact area and is conveyed out of the fixing device in the direction of arrow D in the figure.
Here, when the transfer target 47 is inserted into a region upstream of the opposed contact region, that is, a nip portion formed by the pair of pressure rolls 41 and 42, heat and pressure are applied there, and unfixed toner The toner constituting the image is melted. When the toner is melted, it acts as an adhesive, and the fixing belt 43 and the transfer target 47 are in an adhesive state. However, in the opposite contact area (cooling part) on the downstream side of the nip part, the toner is cooled. Heat is removed from the fixing belt 43 by the plate 52 and forcedly cooled.

  This deprived heat is used in the first heating section as described above. The temperature of the fixing belt 43 at the peeling portion corresponding to the exit of the section where the fixing belt 43 and the pressure belt 45 are in contact with each other (opposed contact area) is a viscosity at which the toner is solidified to some extent and is easily separated from the fixing belt 43. The cooling unit is forcibly cooled so as to be equal to or lower than the temperature. In the peeling portion, the transfer target 47 is peeled off from the fixing belt 43, proceeds in the direction of arrow D, and is discharged outside the apparatus.

In the fixing device shown in FIG. 5, for example, the cooling unit can perform forced cooling so that the surface temperature of the fixing belt 43 is 100 ° C. or less. The temperature is more preferably adjusted to 90 ° C. or lower.
Further, the surface of the fixing belt 43 at the entrance of the nip portion is heated by the three heating portions so that the temperature becomes equal to or higher than the melting temperature of the toner. In the fixing device shown in FIG. 5, for example, the surface of the fixing belt 43 can be heated to 175 ° C. In this case, the first heating unit can be heated to approximately 115 to 120 ° C, the second heating unit can be heated to approximately 160 to 170 ° C, and the third heating unit can be heated to 175 ° C.

  In the fixing device shown in FIG. 5, the fixing belt 43 is strongly heated by the three heating portions in this way, and since the heating efficiency is high, high-speed fixing can be realized. In addition, the transfer target 47 and the fixing belt 43 that have the remaining heat after fixing are forcibly cooled using the cooling plate 52 and the remaining heat is recovered and reused in the first heating unit. Of course, the peelability is good, and the thermal efficiency is also good. In such a fixing apparatus shown in FIG. 5, the above configuration realizes continuous high-speed fixing of 60 sheets per minute (A4 lateral feed).

  The image forming apparatus and the fixing apparatus applicable to the image forming method of the present invention have been described above by taking the image forming apparatus shown in FIG. 2 and the three fixing apparatuses shown in FIGS. 3 to 5 as specific examples. However, the present invention is not limited to the apparatuses of these embodiments, and various conventionally known image forming apparatuses or fixing apparatuses can be applied. The individual elements described in each of these examples can also be applied in other examples.

  In the image forming method of the present invention, prior to introducing the transferred body on which the unfixed toner image is formed into the fixing device, the surface temperature of the transferred body on the side on which the unfixed toner image is formed is 50. It can be preheated (hereinafter sometimes referred to as “preheating”) so as to be at or above the temperature. By setting the surface temperature of the transferred body to 50 ° C. or higher by preheating, the moisture taken into the transferred body becomes water vapor, which makes it easy for molecular motion. As a result, the moisture content is reduced, and water vapor can easily escape from the transfer target in the fixing process, preventing blistering and the release agent in the toner easily melting. Therefore, it is advantageous for improving the releasability of the transfer object from the fixing device.

Hereinafter, the present invention will be described more specifically with reference to examples. Of course, the present invention is not limited to the examples described below. In the examples, “parts” and “%” represent “parts by mass” and “mass%”, respectively, unless otherwise specified.
Note that the method for evaluating the sheet characteristics will be described later.

[Coated paper]
(Coated paper I)
Filtration degree of 500 ml obtained by beating a pulp slurry obtained by mixing 80 parts by mass of LBKP (hardwood bleached kraft pulp) and 20 parts by mass of NBKP (softwood bleached kraft pulp) with Niagara Beata (manufactured by Kumagai Riki Kogyo Co., Ltd.) In addition to 100 mass parts of the pulp solid content of this pulp slurry, 5 mass parts of light calcium carbonate (Tama Pearl TP-121, manufactured by Okutama Kogyo Co., Ltd.), cationized starch (trade name: MS4600, Nippon Food Chemical Co., Ltd.) 0.15 parts by mass of Kogyo Co., Ltd.) and 0.05 parts by mass of alkenyl succinic anhydride (Fibran 81, Oji National Co., Ltd.) were added. These mixtures were diluted with white water to prepare a paper slurry having a solid content concentration of 0.3%.

After stirring the obtained stock slurry for 2 hours, the fiber orientation ratio by the ultrasonic propagation velocity method (SST210, manufactured by Nomura Corp.) is 1.20 using an oriented sheet former (manufactured by Kumagai Riki Kogyo Co., Ltd.). Then, 1 g / m ² of oxidized starch (Ace A, manufactured by Oji Cornstarch Co., Ltd.) was applied to the obtained wet paper with a size press machine, dried, and then machine-calendar using a machine calendar. Smoothing treatment was performed so that the smoothness was 40 seconds, and a base material having a basis weight of 71 g / m ² was obtained.

  On the other hand, 100% by mass of pigment component [30% by mass of light calcium carbonate (trade name: Tama Pearl T-123, manufactured by Okutama Kogyo Co., Ltd.) and 70% by mass of kaolin (Ultra White 90, manufactured by Engelhard Co., Ltd.)] On the other hand, as an adhesive, oxidized starch (Ace A, manufactured by Oji Cornstarch Co., Ltd.) 3% by mass (solid ratio to pigment; hereinafter the same in this example) and a synthetic adhesive (LX430 and 2507H, blending ratio 20:80, 15% by mass of Nippon Zeon Co., Ltd.) and 0.3% by mass of a dispersant (Aron T-40, manufactured by Toa Gosei Co., Ltd.) were blended to prepare a coating composition to be applied to the substrate. .

The obtained coating composition was coated on both sides of the obtained substrate with a blade coater so that the dry weight was 7 g / m ² per side, dried, and then dried on a super calender with a roll temperature of 50 ° C. Smoothing treatment was performed so that the polishing smoothness was 500 seconds to obtain a coated paper having a basis weight of 85 g / m ² . The tensile modulus of elasticity of the CD direction prescribed | regulated to JIS-P8113 of the obtained coated paper was 3000 MPa.

(Coated paper II)
In the same manner as described for the coated paper I, a paper slurry having a solid content concentration of 0.3% was prepared. After stirring the obtained stock slurry for 2 hours, the fiber orientation ratio by the ultrasonic propagation velocity method (SST210, manufactured by Nomura Corp.) is 1.20 using an oriented sheet former (manufactured by Kumagai Riki Kogyo Co., Ltd.). Then, 1 g / m ² of oxidized starch (Ace A, manufactured by Oji Cornstarch Co., Ltd.) was applied to the obtained wet paper with a size press machine, dried, and then dried with a machine calender. Smoothing treatment was performed so that the degree was 40 seconds to obtain a base material having a basis weight of 71 g / m ² .

  On the other hand, 100% by mass of pigment component [light calcium carbonate (trade name: Tama Pearl T-123, manufactured by Okutama Kogyo Co., Ltd.) 15% by mass, kaolin (Ultra White 90, manufactured by Engelhard Co., Ltd.) 80% by mass, Organic pigment (NIpol MH5055, manufactured by Nippon Zeon Co., Ltd.) 5% by mass], as an adhesive, oxidized starch (Ace A, manufactured by Oji Cornstarch Co., Ltd.) 3% by mass (solid ratio to pigment; hereinafter the same in this example) ), 15% by mass of a synthetic adhesive (0623A and 0640, blending ratio 15:85, manufactured by JSR Corporation), and 0.3% by mass of a dispersant (Aron T-40, manufactured by Toa Gosei Co., Ltd.) Thus, a coating composition to be applied to the substrate was prepared.

The obtained coating composition was coated on both sides with a blade coater so that the dry weight would be 7 g / m ^{2 on} one side. After drying, the Oken type smoothness was measured with a super calendar at a roll temperature of 60 ° C. A smoothing process was performed so as to be 1000 seconds to obtain a coated paper having a basis weight of 85 g / m ² . The tensile modulus of elasticity of the obtained coated paper in the CD direction was 3000 MPa.

(Coated paper III)
The basis weight of 85 g is the same as the method described in the above coated paper I except that the size press-treated material of the base material is changed from oxidized starch to polyvinyl alcohol (PVA117, manufactured by Kuraray Co., Ltd.) and treated at ² g / m ^2. A coated paper of / m ² was obtained. The tensile modulus of elasticity of the obtained coated paper in the CD direction was 5000 MPa.

(Coated paper IV)
In the coated paper III, when producing the base material, the base weight of the base material is 50 g / m ^2, and the coating composition similar to that of the coated paper III is bladed so that the dry weight is 5 g / m ^{2 on} one side. Each operation was performed in the same manner as in the above coated paper III except that the base material having a basis weight of 50 g / m ² was coated by a coater to obtain a coated paper having a basis weight of 60 g / m ² . The tensile modulus of elasticity of the obtained coated paper in the CD direction was 5000 MPa.

(Coated paper V)
In the coated paper I, when the base material is manufactured, the base weight of the base material is 105 g / m ² , and the coated paper I
Each operation was carried out in the same manner as in the above coated paper III, except that the coating composition similar to the above was coated on both sides with a blade coater so that the dry weight was 11 g / m ^{2 on} one side. The coated paper having a basis weight of 127 g / m ² was obtained. The tensile modulus of elasticity of the obtained coated paper in the CD direction was 3000 MPa.

(Coated paper VI)
In the coated paper I, a coated paper having a basis weight of 85 g / m ² was obtained by the same method except that the base material was produced so that the ultrasonic wave propagation fiber orientation ratio was 1.60. It was. The tensile modulus of elasticity of the obtained coated paper in the CD direction was 2500 MPa.

(Coated paper VII)
In the coated paper I, the breakdown of the pigment component is [light calcium carbonate (trade name: Tama Pearl T-123, manufactured by Okutama Kogyo Co., Ltd.) 50 mass%, kaolin (Ultra White 90, manufactured by Engelhard Co., Ltd.) The coated paper having a basis weight of 85 g / m ² was obtained in the same manner except that the smoothing treatment was performed using a super calender so that the Oken smoothness was 300 seconds. The tensile modulus of elasticity of the obtained coated paper in the CD direction was 3000 MPa.

<Evaluation of paper characteristics>
The paper characteristics of the coated paper of each example produced as described above were evaluated. Including those already described, they are summarized in Table 1 below. The method for evaluating the paper characteristics is as described later.

<Evaluation method of paper characteristics>
(1) Basis weight It measured by the method prescribed | regulated to JISP-8124.
(2) Smoothness JTappINo. Measured by the method specified in 5 (Oken smoothness).
(3) Tensile modulus in CD direction It was measured using a Tensilon universal testing machine RTM-250 manufactured by Orientec Co., Ltd. according to the conditions defined in JIS-P8113.

[Toner and developer]
-Preparation of resin fine particle dispersion (1)-
-Styrene: 480 parts by mass-n-butyl acrylate: 120 parts by mass-Acrylic acid: 12 parts by mass-Dodecanethiol: 12 parts by mass The above components were mixed and dissolved to prepare a solution.
On the other hand, 12 parts by weight of an anionic surfactant (Dowfax, manufactured by Dow Chemical Co., Ltd.) was dissolved in 250 parts by weight of ion-exchanged water, and then the above solution was added thereto and dispersed and emulsified in a flask (monomer). Emulsion A) was prepared.

Furthermore, 1 part by mass of an anionic surfactant (Dowfax, manufactured by Dow Chemical Co., Ltd.) was dissolved in 555 parts by mass of ion-exchanged water and charged into a polymerization flask. Subsequently, the polymerization flask is sealed, a reflux tube is installed, and the polymerization flask is heated to 75 ° C. in a water bath while being slowly stirred while injecting nitrogen.
Thereafter, a solution obtained by dissolving 9 parts by mass of ammonium persulfate in 43 parts by mass of ion-exchanged water was dropped into the polymerization flask through a metering pump over 20 minutes. Over 200 minutes.
Thereafter, the polymerization flask was kept at 75 ° C. for 3 hours while stirring slowly, to complete the polymerization.
As a result, an anionic resin fine particle dispersion (1) having a center diameter of 240 nm, a glass transition temperature of 54 ° C., a weight average molecular weight of 25000, and a solid content of 42% was obtained.

-Preparation of resin fine particle dispersion (2)-
In the preparation of the resin fine particle dispersion (1), except that the amount of acrylic acid was changed to 8 parts by mass and the amount of dodecanethiol was changed to 16 parts by mass, it was prepared in the same manner as the resin fine particle dispersion (1). An anionic resin fine particle dispersion (2) having a wavelength of 190 nm, a glass transition temperature of 50 ° C., a weight average molecular weight of 19000 and a solid content of 42% was obtained.

-Preparation of colorant particle dispersion (1)-
-Yellow pigment (Clariant Japan, PY74): 50 parts by mass-Anionic surfactant (Daiichi Kogyo Seiyaku, Neogen R): 5 parts by mass-Ion-exchanged water: 200 parts by mass The above components are mixed and dissolved. Then, the mixture was dispersed for 10 minutes with a homogenizer (manufactured by IKA, Ultra Tarrax) to obtain a colorant particle dispersion (1) having a center diameter of 200 nm and a solid content of 21.5%.

-Preparation of Colorant Particle Dispersion (2)-
The colorant particle dispersion (1) was prepared in the same manner as the colorant particle dispersion (1) except that a cyan pigment (manufactured by Dainichi Seika Co., Ltd., copper phthalocyanine B15: 3) was used instead of the yellow pigment. Thus, a colorant particle dispersion (2) having a center diameter of 190 nm and a solid content of 21.5% was obtained.

-Preparation of Colorant Particle Dispersion (3)-
In the preparation of the colorant particle dispersion (1), except that a magenta pigment (manufactured by Dainichi Ink Chemical Co., PR122) was used instead of the yellow pigment, it was prepared in the same manner as the colorant particle dispersion (1). A colorant particle dispersion (3) having a center diameter of 160 nm and a solid content of 21.5% was obtained.

-Preparation of Colorant Particle Dispersion (4)-
The colorant particle dispersion (1) was prepared in the same manner as the colorant particle dispersion (1) except that a black pigment (Cabot, carbon black) was used instead of the yellow pigment, and the center diameter was 170 nm. A colorant particle dispersion (3) having a solid content of 21.5% was obtained.

-Preparation of release agent particle dispersion-
HNP09 (Nippon Seiwa Wax Melting Point 75 ° C.): 50 parts by mass Anionic Surfactant (Dow Chemical Dow Fax): 5 parts by mass Ion-exchanged water: 200 parts by mass The above components are heated to 110 ° C. After sufficiently dispersing with a homogenizer (IKA, Ultra Tarrax T50), it is dispersed with a pressure discharge type homogenizer (Gorin homogenizer, Gorin), release agent particles having a center diameter of 115 nm and a solid content of 21.0%. A dispersion was obtained.

<Developer I>
(Preparation of toner particles)
-Resin fine particle dispersion (2): 126.05 parts by mass (resin solid content: 52.94 parts by mass)
Colorant particle dispersion (1): 39.5 parts by mass (pigment solid content: 8.5 parts by mass)
-Release agent particle dispersion: 38.1 parts by mass (release agent solid content: 10 parts by mass)
-Polyaluminum chloride: 0.13 parts by mass The above components were thoroughly mixed and dispersed in a round stainless steel flask with a homogenizer (IKA, Ultra Turrax T50), and then the flask was stirred with a heating oil bath. While heating to 43 ° C. and holding at 48 ° C. for 50 minutes, 68 parts by mass of resin fine particle dispersion (2) (28.56 parts by mass of resin) was added and gently stirred. Thereafter, the temperature of the solution in the flask was raised to 45 ° C. and maintained at that temperature for 100 minutes, and it was confirmed with a Coulter counter that the particle size distribution became narrower.

Thereafter, the pH in the flask was adjusted to 6.5 with a 0.5 mol / liter sodium hydroxide aqueous solution, and then heated to 95 ° C. while stirring was continued. During the temperature increase to 95 ° C., the pH in the flask was normally lowered to 5.3 but kept as it was.
After completion of the reaction, the mixture was cooled, filtered, sufficiently washed with ion exchange water, and then solid-liquid separated by Nutsche suction filtration. And it re-dispersed in 3 liters of ion exchange water at 40 ° C., and stirred and washed at 300 rpm for 15 minutes. This washing operation was repeated 5 times, followed by solid-liquid separation by Nutsche suction filtration, and then vacuum-dried for 12 hours to obtain toner particles.
When the particle size of the toner particles was measured with a Coulter counter, the volume average particle size D _50v was 3.5 μm, the volume average particle size distribution index GSDv was 1.20, and the surface property index was 1.49. Further, the shape factor SF1 of the toner particles obtained from the observation of the shape with Luzex was 123.

To 50 parts by mass of the toner particles, 1.6 parts by mass of hydrophobic silica (manufactured by Cabot, TS720) was added and mixed with a sample mill to obtain an externally added toner.
Then, using a ferrite carrier having an average particle diameter of 50 μm coated with 1% of polymethyl methacrylate (manufactured by Soken Chemical Co., Ltd .: weight average molecular weight: 60000), the above externally added toner is weighed so that the toner concentration becomes 5%. Both were stirred and mixed in a ball mill for 5 minutes to prepare a yellow developer having a release agent content of 10% by mass and a toner volume average particle diameter D _50v of 3.5 μm.

A cyan developer was prepared in the same manner except that the colorant particle dispersion (2) was changed to the colorant particle dispersion (1). The toner had a release agent content of 10% by mass, a volume average particle diameter D _50v of 3.5 μm, a surface property index of 1.49, and a shape factor SF1 of 123.

A magenta developer was prepared in the same manner except that the colorant particle dispersion (1) was replaced with the colorant particle dispersion (3). The toner had a release agent content of 10% by mass, a volume average particle diameter D _50v of 3.5 μm, a surface property index of 1.49, and a shape factor SF1 of 123.

A black developer was prepared in the same manner except that the colorant particle dispersion (4) was replaced with the colorant particle dispersion (4). The toner had a release agent content of 10% by mass, a volume average particle diameter D _50v of 3.5 μm, a surface property index of 1.49, and a shape factor SF1 of 123.

<Developer II>
With respect to Developer I, the same method was used except that the blending amount of the resin particle dispersion (2) and the release agent particle dispersion was changed as follows, and the release agent amount was 5 mass% and the volume average particle diameter. Yellow, cyan, magenta, and black developer of toners each having a D _50v of 3.5 μm were obtained. The surface property index and the shape factor SF1 of each toner were adjusted to be the same as those of the developer I.
-Resin fine particle dispersion (2): 137.95 parts by mass (resin solid content: 57.94 parts by mass)
-Release agent particle dispersion: 23.81 parts by mass (release agent solid content: 5 parts by mass)

<Developer III>
With respect to Developer I, the same method was used except that the blending amounts of the resin particle dispersion (2) and the release agent particle dispersion were changed as follows, and the release agent amount was 15% by mass and the volume average particle diameter. Yellow, cyan, magenta, and black developer of toners each having a D _50v of 3.5 μm were obtained. The surface property index and the shape factor SF1 of each toner were adjusted to be the same as those of the developer I.
-Resin fine particle dispersion (2) 114.14 parts by mass (resin solid content: 47.94 parts by mass)
Release agent particle dispersion 71.42 parts by mass (release agent solid content: 15 parts by mass)

<Developer IV>
-Resin fine particle dispersion (2): 126.05 parts by mass (resin solid content: 52.94 parts by mass)
Colorant particle dispersion (1): 39.5 parts by mass (pigment solid content: 8.5 parts by mass)
-Release agent particle dispersion: 38.1 parts by mass (release agent solid content: 10 parts by mass)
-Polyaluminum chloride: 0.13 parts by mass The above components were thoroughly mixed and dispersed in a round stainless steel flask with a homogenizer (IKA, Ultra Turrax T50), and then the flask was stirred with a heating oil bath. While heating to 43 ° C. and holding at 48 ° C. for 60 minutes, 68 parts by mass of resin fine particle dispersion (2) (28.56 parts by mass of resin) was added and gently stirred. Thereafter, the temperature was raised to 45 ° C., maintained at that temperature for 130 minutes, and the amount of release agent was 10% by mass, volume average particle size, except that the Coulter counter confirmed that the particle size distribution became narrower. Yellow, cyan, magenta, and black developer of toners having a diameter D _50v of 4.5 μm were obtained. Each toner had a surface property index of 1.49 and a shape factor SF1 of 123, which was equivalent to that of developer I.

<Developer V>
For developer I, except that the resin particle dispersion (2) is changed to the resin dispersion (1), the maximum temperature during aggregation is 50 ° C., and the pH when held at 95 ° C. is 4.1. In this way, yellow, cyan, magenta, and black developers of toner having a release agent amount of 10 mass% and a volume average particle diameter D _50v of 6.0 μm were obtained.

<Toner / developer characteristics measurement method>
The volume average particle diameter D _50v and the average particle size distribution index are the volume and number for the particle size range (channel) divided based on the particle size distribution measured with a Coulter Multisizer II (manufactured by Beckman-Coulter). The cumulative distribution was drawn from the small particle size side. Here, the average particle diameter D _16v and the number average particle diameter D _{16P are} the average particle diameter of ₁₆ %, and the average particle diameter D _50v and the average number of particle diameters D _50v and D _50P are 84%. _Were determined as a volume average particle diameter D _84v and a number average particle diameter D _84P . Using these, the volume average particle size distribution index (GSDv) is calculated as (D _84v / D _16V ) ^1/2 and the number average particle size distribution index (GSDp) is calculated as (D _84P / D _16P ) ^1/2 .

  The shape factor SF1 of the toner used in the examples / comparative examples was determined as follows. First, an optical microscope image of the toner dispersed on the slide glass is taken into a Luzex image analyzer through a video camera, and the peripheral length (ML) and projected area (A) of 50 or more toners are measured. The toner shape factor SF1 was determined.

<Method for measuring molecular weight of binder resin>
The weight average molecular weight of the binder resin component of the toner used in Examples / Comparative Examples was measured using the following equipment. GPC uses “HLC-8120GPC, SC-8020 (manufactured by Tosoh Corporation)”, and the column uses two “TSKgel, SuperHM-H (6.0 mm ID × 15 cm, manufactured by Tosoh Corporation)” THF (tetrahydrofuran) was used as an eluent.
Here, the measurement conditions include a sample concentration of 0.5% and a flow rate of 0.6 ml / min. The sample injection volume was 10 μl, the measurement temperature was 40 ° C., and measurement was performed using an IR detector. The calibration curve is “polystylen standard sample TSK standard” manufactured by Tosoh Corporation: “A-500”, “F-1”, “F-10”, “F-80”, “F-380”, “A-2500”. ”,“ F-4 ”,“ F-40 ”,“ F-128 ”, and“ F-700 ”.

(Measuring method of melting point of release agent and glass transition temperature of binder resin)
The melting point of the release agent of the toner used in Examples / Comparative Examples and the glass transition temperature of the binder resin component were determined from the main maximum peak measured according to ASTM D3418-8.
DSC-7 manufactured by PerkinElmer was used for measurement of the main maximum peak. The temperature correction of the detection part of this apparatus was performed using the melting point of indium and zinc, and the heat quantity was corrected using the heat of fusion of indium. As the sample, an aluminum pan was used, an empty pan was set as a control, and the measurement was performed at a heating rate of 10 ° C./min.

[Image forming apparatus]
The following image forming apparatuses I to III were used for image formation using a combination of the above-described toner (developer) and coated paper.
(Image forming apparatus I)
The image forming apparatus I is an image forming apparatus (Docucenter Color 500, manufactured by Fuji Xerox Co., Ltd.) having the configuration shown in FIG. 2 incorporating the fixing device I shown in FIG.
(Image forming apparatus II)
The image forming apparatus II uses the fixing apparatus II shown in FIG. 4 instead of the fixing apparatus I of the image forming apparatus I, and the detailed configuration of the fixing apparatus II is the same as described above.
(Image forming apparatus III)
The image forming apparatus III uses the fixing apparatus III shown in FIG. 5 instead of the fixing apparatus I of the image forming apparatus I. The detailed configuration of the fixing apparatus III is the same as described above.

[Evaluation]
As shown in Table 1, the coated papers I to VII and the developers I to V are combined to form an image forming apparatus I.
Using -III, a recording test was performed to form each image with a secondary color solid image of yellow and magenta at an image area ratio of 200%. The results are shown in Table 1 below.

<Quality evaluation>
The evaluation shown in Table 1 (image defects due to fixing wrapping and peeling failure) is performed by visual evaluation of the formed image, and the evaluation results in Table 1 are based on the following evaluation criteria.
(Double-circle): The image defect accompanying winding and peeling defect does not generate | occur | produce at all.
○: No wrapping occurs, but a slight image-like state is observed, but it is in an allowable range.
(Triangle | delta): Although winding does not generate | occur | produce, the state like the slight spot of an image generate | occur | produces and it has reached the level which cannot be tolerated.
X: Winding occurs.

Wrapping and peeling to a fixing device when an image is formed using various coated papers having a basis weight of 85 g / m ² , Oken type smoothness of 500 seconds or more, and various toners having a volume average particle diameter of 3.5 μm. 6 is a graph showing image defects caused by defects in relation to the content of a release agent in toner and the tensile elastic modulus in the CD direction of coated paper. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus preferably used in an image forming method of the present invention. FIG. 3 is a schematic diagram illustrating an example of a heat roll type fixing device that is preferably used in the image forming method of the present invention. FIG. 2 is a schematic diagram illustrating an example of a belt-roll nip type fixing device that is preferably used in the image forming method of the present invention. FIG. 6 is a schematic diagram illustrating another example of a belt-roll nip type fixing device that is preferably used in the image forming method of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heat roll 2 Crimp roll 3, 3 'Heat source 4 Fixing member surface layer 5, 5' Elastic layer 6 Unfixed toner image 7 Transfer object 8 Core 11 Photoconductor (latent image carrier)
DESCRIPTION OF SYMBOLS 12 Charger 13 Exposure apparatus 14 Developing apparatus 14a, 14b, 14c, 14d Developer 15 Belt-shaped intermediate transfer body 16 Cleaner 17 Photostatic dischargers 18a, 18b, 18c Spindle roll 19 Transfer roll 21 Heat fixing rolls 22, 23 , 24 Support roll 25 Endless belt 26 Compression coil spring 27 Cover layer 27a Underlayer 27b Top coat layer 30 Temperature sensor 31 Pressure applying member 31a Base plate 31b Elastic layer 31c Low friction layer 32 Core 35 Heat source (halogen lamp)
36 Unfixed toner image 37 Transfer object 38 Motor 41, 42 Pressure roll 43 Fixing belts 44a, 44b, 44c Temperature sensor 45 Pressure belt 47 Transfer object 48, 49 Heating roll 51 Heating plate 52 Cooling plate 53 Heat pipe 55a 55b heater

Claims (7)

A fixing step of fixing an unfixed toner image formed on the surface of the coated paper provided with the coating layer by heating and pressing, and forming an image;
The coated paper has a base material and a coating layer containing a pigment and / or a colorant as a main component on at least one side of the base material, and the unfixed toner image is made of toner containing a release agent. In the image forming method,
The volume average particle size of the toner is at 5μm or less, the Oken type smoothness of the surface coating layer is provided in the coated paper Ri der least 500 seconds, a basis weight of the coated paper is 100 g / m ² or less, and an image forming method CD direction of the tensile modulus of the coated paper, characterized in der Rukoto least 5000 MPa. ^2. The image forming method according to claim 1, wherein a maximum toner amount per single color when the unfixed toner image is formed is 0.35 mg / cm ² or less. The image forming method according to claim 1 or claim 2, wherein the amount of the releasing agent contained in the toner is 5% by mass or more. The image formation according to any one of claims 1 to 3 , wherein a coating amount per one side of the base material when forming the coating layer is 5 g / m ² or more in terms of solid content. Method. The fixing step uses a fixing device including a pair of rolls whose outer peripheral surfaces are in contact with each other to form a nip portion,
The unfixed toner image has said coated paper formed in the coating layer surface, and inserted into the nip portion, claim 1-4, characterized in that it is carried out by heating and pressing 1 The image forming method described in 1. In the fixing step, the outer peripheral surfaces of the endless belt and the heating roll having an elastic layer that are in contact with each other face to face each other, and the inner peripheral surface of the endless belt so as to press the outer peripheral surface of the heating roll. And a fixing device including a pressure applying member arranged
The unfixed toner image has said coated paper formed in the coating layer surface, and inserted into the nip portion, claim 1-4, characterized in that it is carried out by heating and pressing 1 The image forming method described in 1. The fixing step includes a pair of endless belts that form opposed contact areas in which the outer peripheral surfaces of each other are opposed to each other along the rotation direction, and the pair of endless belts located upstream of the opposed contact area in the rotation direction. Using a fixing device including a pair of rolls that press the peripheral surface to form a nip portion,
The coated paper on which the unfixed toner image is formed on the surface of the coating layer is inserted into the nip portion and heated and pressurized, and then held between the pair of endless belts in the rotational direction of the opposed contact region. forced cooled while transported to the downstream side, the image formation according to any one of claims 1-4, characterized in that it is carried out by peeling from the pair of endless belts with exits the opposing contact region Method.

Images