JP4010530B2 - Image forming method and toner used therefor - Google Patents

Description

【００３６】
【発明の効果】
以上、詳細かつ具体的な説明から明らかなように、本発明を用いることにより、片面のみだけでなく、両面同時に印刷或いは複写可能な非接触定着方式においても、転写不良による画像欠陥もなく、従来のものより、より一層、好適な画像光沢や色の鮮やかさが得られることが可能になるという極めて優れた効果を奏するものである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a single-sided or double-sided simultaneous image forming method and toner using a non-contact heat fixing system such as an oven in the field of electrophotographic electrostatic recording.
[0002]
[Prior art]
The fixing of the powder toner electrophotographic process can be broadly classified into (1) a non-heating fixing method using pressure and a solvent, and (2) an oven fixing method in which heated air is supplied to the image holding member for fixing. There are three types, a non-contact heating fixing method that does not directly heat a toner image typified by a radiation fixing method that supplies heat, and (3) a contact heating method that supplies heat and pressure simultaneously with a heat roll. Many photocopiers and printers using an electrophotographic process have become widely used because of thermal efficiency. However, it is difficult to fix unfixed images on both sides simultaneously with thermal roll fixing. Therefore, the non-contact fixing method is adopted in the field of duplex copying or printing at high speed. However, since the image fixed by the non-contact heat fixing method becomes a so-called matte low gloss image, there is a problem when a glossy image is preferred. In addition, even if fixing on only one side is not so problematic, fixing on both sides simultaneously results in a lower gloss image, which is a big problem.
[0003]
As a toner suitable for the non-contact heat fixing method, for example, JP-A-6-282102 discloses the use of two types of resins having different glass transition points and melt viscosities. In this case, the fixing itself is sufficiently performed, but a suitable image gloss or color vividness has not been obtained. In particular, when copying and printing on both sides at the same time, an image with extremely low gloss was obtained.
Japanese Patent Laid-Open No. 10-39539 discloses specifying the relationship between toner particles and the BET value and passing a pressure roller after fixing at a non-contact fixing unit. In some cases, there were problems with image gloss and color vividness.
[0004]
[Problems to be solved by the invention]
The object of the present invention is that there is no image defect due to transfer failure in the non-contact heat fixing method that can be printed or copied not only on one side but also on both sides at the same time. An object of the present invention is to provide an image forming method capable of obtaining vividness and a toner therefor.
[0005]
[Means for Solving the Problems]
The present inventors completed the present invention as a result of intensive studies to improve the above-mentioned drawbacks.
That is, the above object is (1) “image forming method using non-contact heat fixing method” of the present invention, wherein the toner used has a circularity of 0.93 or more and the toner at 140 ° C. A double-sided simultaneous image forming method characterized in that the melt viscosity is 120 mPas · sec or less, and further, after fixing by a non-contact heat fixing method, post-processing is performed with a heated pressure roller. The simultaneous double-sided image forming method according to item (1), wherein the toner images of a plurality of colors obtained by developing the electrostatic latent image are fixed on the image holding member, and then fixed. 3) “The double-sided simultaneous image forming method according to (2) above, wherein the toner images of yellow, magenta, cyan and black are fixed after being superimposed”, ( 4 ) “The toner is an additive As at least hydrophobic treatment Silica, titania, said first (1), characterized in that either one or those of a plurality of types of alumina are used together claim, second (3) section dual-side image forming method according to any one " Achieved by:
[0006]
Further, the above object is ( 5 ) “image forming method using non-contact heat fixing method” of the present invention, wherein the toner used has a circularity of 0.93 or more, and the toner at 140 ° C. A single-sided single image forming method having a melt viscosity of 120 mPas · sec or less, further fixed by a non-contact heat fixing method, and then subjected to post-processing by a heated pressure roller ”, ( 6 )“ Toners of different colors The single-sided single image forming method according to item ( 5 ), wherein the toner images of a plurality of colors obtained by developing the electrostatic latent image are fixed on the image holding member, and then fixed. 7 ) “The single-sided single-side image forming method according to item ( 6 ), wherein the toner images are fixed after overlapping toner images of yellow, magenta, cyan, and black”, ( 8 ) “The toner is an additive. As at least hydrophobic Sense silica, titania, said first (5) to one side independent image forming method according to any one of the first (7), characterized in that either one or those of a plurality of types of alumina are used in combination " Achieved by:
[0007]
The present invention is described in detail below.
According to the present invention, by controlling the circularity of the toner shape to 0.93 or more in particular, it is possible to reduce as much as possible additives such as silica added for the purpose of improving image defects due to transfer defects, so-called worm-eaten images. It became. This makes it possible to expose the surface of the toner moderately, the adjacent resin portions of the melted toner come into contact, and then the surface tension spreads along the gap formed in the toner contact portion, resulting in smoothness. An image surface can be obtained. Further, according to the present invention, as a result of studying the melt viscosity at 140 ° C. of this toner, when the melt viscosity is 120 mPas · sec or less, the above phenomenon is further accelerated, and a suitable image gloss is obtained. And the vividness of the color was obtained. In addition, according to the present invention, after fixing by a non-contact fixing method, by performing post-processing with a heated fixing roller, the surface of the image becomes smoother, and more suitable image gloss and color vividness are obtained. Obtained. For single-sided copying or printing, acceptable ranges can be achieved by including either one of these combinations, at least 140 ° C melt viscosity or post-processing with a heated fuser roller, but preferably three It is a combination. On the other hand, in simultaneous copying or printing on both sides, even if any one of these combinations is missing, suitable image gloss and color vividness cannot be obtained. This is presumably because the thermal energy of the oven or the like is dispersed on both sides in the case of simultaneous use on both sides, so that the absorption of thermal energy on the toner surface is lower than in the case of only one side.
[0008]
The circularity can be measured by various methods. In the present invention, the circularity was determined using a flow particle image analyzer FPA-1000 manufactured by Toa Medical Electronics. The circularity was measured by diluting the toner in an electrolyte solution of 1% saline.
[0009]
About the material used for this invention, it will not be limited, If a condition is satisfy | filled, a well-known material can be used.
As binder resin, styrene such as polystyrene, poly-p-chlorostyrene, polyvinyltoluene, and substituted polymers thereof; styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer Styrene-vinyl naphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate Copolymer, Styrene-ethyl methacrylate copolymer, Styrene-butyl methacrylate copolymer, Styrene-α-Chloromethyl methacrylate copolymer, Styrene-acrylonitrile acid copolymer, Styrene-vinyl methyl ketone copolymer , Styrene-butadiene copolymer Styrene copolymers such as styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid copolymer, styrene-maleic acid ester copolymer; polymethyl methacrylate, polybutyl methacrylate, poly Vinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, epoxy resin, epoxy polyol resin, polyurethane, polyamide, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, aliphatic or alicyclic hydrocarbon resin , Aromatic petroleum resin, chlorinated paraffin, paraffin wax, and the like, which can be used alone or in combination. Of these, polyester resins and epoxy polyol resins are preferred in view of manufacturability and the like. Further, since non-contact heat fixing is exposed to a high temperature for a long time compared to hot roll fixing, the odor due to the generated gas becomes a problem compared to hot roll fixing. Styrene-acrylic copolymers are not preferred because they produce a styrene odor. Regarding polyester resins, if the content of trimellitic acid (including anhydrides and esterified products) in the constituent monomer is 3 mol% or if dodecenyl succinic acid is 2 mol% or more, an odor is easily generated during fixing. .
[0010]
Known dyes and pigments can be used as the colorant, such as carbon black, nigrosine dye, iron black, naphthol yellow S, Hansa yellow (10G, 5G, G), cadmium yellow, yellow iron oxide, ocher, yellow. Lead, Titanium Yellow, Polyazo Yellow, Oil Yellow, Hansa Yellow (GR, A, RN, R), Pigment Yellow L, Benzidine Yellow (G, GR), Permanent Yellow (NCG), Vulcan Fast Yellow (5G, R) , Tartrazine rake, quinoline yellow rake, anthrazan yellow BGL, isoindolinone yellow, bengara, red lead, lead vermilion, cadmium red, cadmium mercurial red, antimon vermilion, permanent red 4R, para red, phissa red Parachlor ortho nitroani Red, Resol Fast Scarlet G, Brilliant Fast Scarlet, Brilliant Carmine B, Permanent Red (F2R, F4R, FRL, FRLL, F4RH), Fast Scarlet VD, Belkan Fast Rubin B, Brilliant Scarlet G, Resol Rubin GX, Permanent Red F5R, Brilliant Carmine 6B, Pogment Scarlet 3B, Bordeaux 5B, Tolujing Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Medium, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarin Lake, Thio Indigo Red B, Thioindigo Maroon, Oil Red, Quinacridone Red, Pyrazolone Red, Poly Zored, Chrome Vermilion, Benzidine Orange, Perinone Orange, Oil Orange, Cobalt Blue, Cerulean Blue, Alkaline Blue Lake, Peacock Blue Lake, Victoria Blue Lake, Metal Free Phthalocyanine Blue, Phthalocyanine Blue, Fast Sky Blue, Indanthrene Blue (RS, BC), indigo, ultramarine blue, bitumen, anthraquinone blue, fast violet B, methyl violet lake, cobalt purple, manganese purple, dioxane violet, anthraquinone violet, chrome green, zinc green, chromium oxide, pyridian, emerald green, pigment Green B, Naphthol Green B, Green Gold, Acid Green Lake, Malachite Green Lake, Phtha Russia Nin green, anthraquinone green, titanium oxide, zinc white, litbon and mixtures thereof can be used. The amount used is generally 0.1 to 50 parts by weight per 100 parts by weight of the binder resin. In addition, the melt viscosity of the binder resin was measured by a constant temperature method using an elevated flow tester (CFT-500: manufactured by Shimadzu Corporation) under the conditions of a 1 mm diameter pore of the die and a pressure of 20 kg / cm ² .
[0011]
The toner of the present invention may contain a charge control agent as necessary. Known charge control agents can be used, such as nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdate chelate pigments, rhodamine dyes, alkoxy amines, quaternary ammonium salts (fluorine-modified 4 Secondary ammonium salts or compounds, tungsten simple substances or compounds, fluorine activators, salicylic acid metal salts, and metal salts of salicylic acid derivatives.
[0012]
In the present invention, the amount of charge control agent used is determined by the toner production method including the type of binder resin, the presence or absence of additives used as necessary, and the dispersion method, and is uniquely limited. However, it is preferably used in the range of 0.1 to 10 parts by weight with respect to 100 parts by weight of the binder resin. The range of 2 to 5 parts by weight is preferable. If the amount is less than 0.1 parts by weight, the toner is not practically negatively charged. When the amount exceeds 10 parts by weight, the chargeability of the toner is too high, and the electrostatic attraction force with the carrier increases, leading to a decrease in developer fluidity and a decrease in image density.
[0013]
Further, for example, silica fine particles, hydrophobic silica, fatty acid metal salts (such as zinc stearate and aluminum stearate), metal oxides (such as titania, alumina, tin oxide, and antimony oxide), fluoropolymers, etc. may be contained as additives. Good.
Particularly suitable additives include hydrophobized silica, titania, and alumina fine particles. Examples of the silica fine particles include HDK H 2000, HDK H 2000/4, HDK H 2050EP, HVK21 (manufactured by Hoechst) and R972, R974, RX200, RY200, R202, R805, R812 (manufactured by Nippon Aerosil). Further, as titania fine particles, P-25 (manufactured by Nippon Aerosil Co., Ltd.), STT-30, STT-65C-S (manufactured by Titanium Industry), TAF-140 (manufactured by Fuji Titanium Industry), MT-150W, MT-500B MT-600B (manufactured by Teika). Particularly, the hydrophobized titanium oxide fine particles include T-805 (manufactured by Nippon Aerosil), STT-30A, STT-65S-S (above, manufactured by Titanium Industry), TAF-500T, TAF-1500T (above, Fuji Titanium). Industrial), MT-100S, MT-100T (above, manufactured by Teika), IT-S (produced by Ishihara Sangyo), and the like. Hydrophobized silica fine particles, titania fine particles, and alumina fine particles can be obtained by treating hydrophilic fine particles with a silane coupling agent such as methyltrimethoxysilane, methyltriethoxysilane, or octyltrimethoxysilane.
[0014]
In the present invention, development may be performed by a so-called one-component developing method in which an electrostatic latent image is visualized with toner alone, or an electrostatic latent image is formed using a two-component developer obtained by mixing toner and carrier. You may develop by the two-component developing method which makes visible.
[0015]
Carriers used in the two-component development method are the same as conventional ones such as iron powder, ferrite, and glass beads. These carriers may be those coated with a resin. The resin used in this case is polyfluorinated carbon, polyvinyl chloride, polyvinylidene chloride, phenol resin, polyvinyl acetal, silicone resin or the like. In any case, the mixing ratio of toner and carrier is generally about 0.5 to 6.0 parts by weight of toner with respect to 100 parts by weight of carrier.
[0016]
The toner particle size distribution can be measured by various methods. In the present invention, the toner particle size distribution was measured using a Coulter counter. That is, a Coulter counter TA-II type (manufactured by Coulter) was used as a measuring device, and an interface (manufactured by Nikkiki) that outputs number distribution and volume distribution was connected to a PC 9801 personal computer (manufactured by NEC). Prepare 1% NaCl aqueous solution using grade sodium chloride.
As a measurement method, 0.1 to 5 ml of a surfactant, preferably alkylbenzene sulfonate, is added as a dispersant to 10 to 15 ml of the electrolytic aqueous solution, and 2 to 20 mg of a measurement sample is further added. Disperse for ~ 3 minutes. Into another beaker, 100 to 200 ml of an electrolytic aqueous solution was added, and the sample dispersion was added to a predetermined concentration therein, and 2 to 2 on the basis of the number using a 100 μm aperture as an aperture by the Coulter Counter TA-II type. The particle size distribution of 40 μm particles was measured, the volume distribution and number distribution of 2 to 40 μm particles were calculated, and the volume average particle size obtained from the volume distribution was determined.
[0017]
As an example of a method for producing the toner according to the present invention, first, the binder resin, the pigment or dye as the colorant, the charge control agent, the lubricant, other additives, etc. are first mixed with a mixer such as a Henschel mixer. After thorough mixing, batch type two rolls, Banbury mixer and continuous twin screw extruder, for example, KTK type twin screw extruder manufactured by Kobe Steel, TEM type twin screw extruder manufactured by Toshiba Machine Co., Ltd., KCK 2-screw extruder manufactured by Ikekai Tekko Co., Ltd., PCM type twin-screw extruder manufactured by Ikekai Tekko Co., Ltd., KEX type twin-screw extruder manufactured by Kurimoto Iron Works, Ltd., and continuous kneaders such as Kneader manufactured by Buss Co., Ltd. The constituent materials are kneaded well using, and after cooling, coarsely pulverized using a hammer mill or the like. In the case of a color toner, for the purpose of improving the dispersion of the pigment, it is common to use a master batch obtained by previously melt-kneading a part of the binder resin and the pigment as the colorant. Furthermore, these coarsely pulverized products are finely pulverized by using a fine pulverizer or a mechanical pulverizer using a jet airflow alone or in combination, and classified by a classifier using a swirling airflow or a classifier using a Coanda effect. A toner having a circularity and a particle size of 1 is obtained.
[0018]
【Example】
The present invention will be described more specifically with reference to the following examples, but the present invention is not limited thereto. All the parts are parts by weight.
First, some examples of toner production according to the present invention are shown below.
[0019]
[Toner Production Example 1]
(Black toner)
Water 1200 parts phthalocyanine green water-containing cake (solid content 3%) 200 parts carbon black (MA60 manufactured by Mitsubishi Chemical Corporation) 540 parts is thoroughly stirred with a flasher. To this was added 1200 parts of a polyester resin (acid value; 3, hydroxyl value; 25, Mn; 45000, Mw / Mn; 4.0, Tg; 60 ° C.), and after kneading at 150 ° C. for 30 minutes, 1000 parts of xylene were added. In addition, the mixture was further kneaded for 1 hour, after removing water and xylene, cooled by rolling and pulverized with a pulverizer to obtain a master batch pigment.
100 parts of polyester resin (acid value; 3, hydroxyl value; 25, Mn; 45000,
(Mw / Mn; 4.0, Tg; 60 ° C.)
The master batch 5 parts Zinc salicylate derivative (Bontron E84, Orient Chemical) 4 parts The above materials were mixed in a mixer and then melt-kneaded in a two-roll mill, and the kneaded product was rolled and cooled. Thereafter, pulverization classification was performed to obtain a toner having a volume average particle diameter of 7.5 μm and a circularity of 0.95. Further, 0.8 wt% of hydrophobic silica (H2000, Hoechst, primary particle diameter 20 nm) was added and mixed with a mixer to obtain a black toner. Here, the melt viscosity at 140 ° C. was 96 mPas · sec.
[0020]
[Yellow Toner]
Water 600 parts Pigment Yellow 17 Water-containing cake (solid content 50%) 1200 parts are thoroughly stirred with a flasher. To this was added 1200 parts of a polyester resin (acid value; 3, hydroxyl value; 25, Mn; 45000, Mw / Mn; 4.0, Tg; 60 ° C.), and after kneading at 150 ° C. for 30 minutes, 1000 parts of xylene were added. In addition, the mixture was further kneaded for 1 hour, water and xylene were removed, rolled and cooled, pulverized with a pulverizer, and further passed with 3 rolls to obtain a master batch pigment.
100 parts of polyester resin (acid value; 3, hydroxyl value; 25, Mn; 45000,
(Mw / Mn; 4.0, Tg; 60 ° C.)
The master batch 5 parts Zinc salicylate derivative (Bontron E84, Orient Chemical) 4 parts The above materials were mixed in a mixer and then melt-kneaded in a two-roll mill, and the kneaded product was rolled and cooled. Thereafter, pulverization classification was performed to obtain a toner having a volume average particle diameter of 7.5 μm and a circularity of 0.95. Further, an additive was added in the same manner as the above black toner, and mixed with a mixer to obtain a yellow toner. Here, the melt viscosity at 140 ° C. was 98 mPas · sec.
[0021]
(Magenta toner)
Water 600 parts Pigment Red 57 Water-containing cake (solid content 50%) 1200 parts is thoroughly stirred with a flasher. To this was added 1200 parts of a polyester resin (acid value; 3, hydroxyl value; 25, Mn; 45000, Mw / Mn; 4.0, Tg; 60 ° C.), and after kneading at 150 ° C. for 30 minutes, 1000 parts of xylene were added. In addition, the mixture was further kneaded for 1 hour, water and xylene were removed, and then cooled by rolling, pulverized with a pulverizer, and further passed with a 3-roll mill to obtain a master batch pigment.
100 parts of polyester resin (acid value; 3, hydroxyl value; 25, Mn; 45000,
(Mw / Mn; 4.0; 60 ° C.)
The master batch 5 parts Zinc salicylate derivative (Bontron E84, Orient Chemical) 4 parts The above materials were mixed in a mixer and then melt-kneaded in a two-roll mill, and the kneaded product was rolled and cooled. Thereafter, pulverization classification was performed to obtain a toner having a volume average particle diameter of 7.5 μm and a circularity of 0.95. Further, an additive was added in the same manner as the above black toner and mixed with a mixer to obtain a magenta toner. Here, the melt viscosity at 140 ° C. was 17 mPas · sec.
[0022]
(Cyan toner)
Water 600 parts Pigment Blue 15: 3 Water-containing cake (solid content 50%) 1200 parts are thoroughly stirred with a flasher. To this was added 1200 parts of a polyester resin (acid value; 3, hydroxyl value; 25, Mn; 45000, Mw / Mn; 4.0, Tg; 60 ° C.), and after kneading at 150 ° C. for 30 minutes, 1000 parts of xylene were added. In addition, the mixture was further kneaded for 1 hour, water and xylene were removed, and then cooled by rolling, pulverized with a pulverizer, and further passed with a 3-roll mill to obtain a master batch pigment.
100 parts of polyester resin (acid value; 3, hydroxyl value; 25, Mn; 45000,
(Mw / Mn; 4.0, Tg; 60 ° C.)
The master batch 3 parts Zinc salicylate derivative (Bontron E84, Orient Chemical) 4 parts The above materials were mixed in a mixer and then melt-kneaded in a two-roll mill, and the kneaded product was rolled and cooled. Here, the maximum diameter of the pigment was 0.4 μm. Thereafter, pulverization classification was performed to obtain a toner having a volume average particle diameter of 7.5 μm and a circularity of 0.95. Further, an additive was added in the same manner as the above black toner, and mixed with a mixer to obtain a cyan toner. Here, the melt viscosity at 140 ° C. was 34 mPas · sec.
[0023]
[Toner Production Example 2]
The toner was manufactured in the same manner as in Production Example 1 except that the toner used in Toner Production Example 1 had a circularity other than 0.92.
[0024]
[Toner Production Example 3]
A toner was manufactured in the same manner as in Example 1 except that the resin used in Toner Production Example 1 was changed to a polyol resin (Mn; 5600, Mw / Mn; 5.8, Tg; 63 ° C.). The melt viscosity at 140 ° C. of each toner was 125 mPas · sec for black toner, 121 mPas · sec for yellow toner, 123 mPas · sec for magenta toner, and 122 mPas · sec for cyan toner.
[0025]
[Carrier Production Example 1]
Silicon resin solution (manufactured by Shin-Etsu Chemical Co., Ltd., KR50) 100 parts γ- (2-aminoethyl) aminopropyltrimethoxysilane 3 parts Toluene 100 parts The above formulation was dispersed with a homomixer for 30 minutes to prepare a coating layer forming solution. From this coating layer forming liquid, Carrier A was obtained in which a coating layer was formed on the surface of 1000 parts of spherical ferrite having an average particle diameter of 50 μm using a fluidized bed type coating apparatus.
[0026]
[Example 1]
1.75 kg of carrier A and 70 g of the toner of Production Example 1 were placed in a ball mill and stirred for 30 minutes to obtain a developer. The obtained developer was fixed on a non-contact heating fixing unit heated at 140 ° C. on both sides at the same time, and then post-processed on a fixing roller heated at 120 ° C. Image defects due to gloss and transfer failure were visually evaluated and the results are shown in Table 1. The meaning of the rank is as follows.
Rank 5: Excellent, Rank 4: Good, Rank 3: Acceptable,
Rank 2: Inferior, Rank 1: Very inferior
[Example 2]
1.75 kg of carrier A and 70 g of the toner of Production Example 1 were placed in a ball mill and stirred for 30 minutes to obtain a developer. The resulting developer was developed on one side only, fixed at a non-contact heat fixing unit heated at 140 ° C., and then post-processed with a fixing roller heated at 120 ° C. The evaluation results are shown in Table 1.
[0028]
[Example 3]
1.75 kg of carrier A and 70 g of the toner of Production Example 1 were placed in a ball mill and stirred for 30 minutes to obtain a developer. The resulting developer was developed only on one side and fixed in a non-contact heat fixing section heated at 140 ° C. The evaluation results are shown in Table 1. [0029]
[Example 4]
1.75 kg of carrier A and 70 g of the toner of Production Example 3 were placed in a ball mill and stirred for 30 minutes to obtain a developer. The resulting developer was developed on one side only, fixed at a non-contact heat fixing unit heated at 140 ° C., and then post-processed with a fixing roller heated at 120 ° C. The evaluation results are shown in Table 1. [0030]
[Comparative Example 1]
The developer obtained in Example 1 was fixed on a non-contact heating fixing portion heated at 140 ° C. on both sides simultaneously. The evaluation results are shown in Table 1.
[0031]
[Comparative Example 2]
1.75 kg of carrier A and 70 g of the toner of Production Example 2 were placed in a ball mill and stirred for 30 minutes to obtain a developer. The obtained developer was fixed on a non-contact heating fixing unit heated at 140 ° C. on both sides at the same time, and then post-processed on a fixing roller heated at 120 ° C. The evaluation results are shown in Table 1.
[0032]
[Comparative Example 3]
1.75 kg of carrier A and 70 g of the toner of Production Example 3 were placed in a ball mill and stirred for 30 minutes to obtain a developer. The obtained developer was fixed on a non-contact heating fixing unit heated at 140 ° C. on both sides at the same time, and then post-processed on a fixing roller heated at 120 ° C. The evaluation results are shown in Table 1.
[0033]
[Comparative Example 4]
1.75 kg of carrier A and 70 g of the toner of Production Example 3 were placed in a ball mill and stirred for 30 minutes to obtain a developer. The obtained developer was fixed on a non-contact heat fixing section heated at 140 ° C. on both sides simultaneously. The evaluation results are shown in Table 1.
[0034]
[Comparative Example 5]
1.75 kg of carrier A and 70 g of the toner of Production Example 3 were placed in a ball mill and stirred for 30 minutes to obtain a developer. The resulting developer was developed only on one side and fixed in a non-contact heat fixing section heated at 140 ° C. The evaluation results are shown in Table 1.
[0035]
[Table 1]

[0036]
【The invention's effect】
As described above, as is clear from the detailed and specific description, by using the present invention, not only on one side but also in a non-contact fixing method capable of simultaneously printing or copying on both sides, there is no image defect due to transfer failure and the conventional. It is possible to obtain an extremely excellent effect that it is possible to obtain a more favorable image gloss and color vividness than the above.

Claims (8)

  An image forming method using a non-contact heat fixing method, wherein the toner used has a circularity of 0.93 or more and the melt viscosity at 140 ° C. of the toner is 120 mPas · sec or less. A double-sided simultaneous image forming method characterized in that after fixing by a contact heating fixing method, post-processing is performed with a heated pressure roller.   2. The double-sided simultaneous image forming method according to claim 1, wherein a plurality of color toner images obtained by developing electrostatic latent images with different color toners are fixed after being superimposed on an image holding member.   3. The simultaneous double-sided image forming method according to claim 2, wherein the toner images of yellow, magenta, cyan and black are fixed after being overlapped. The double-sided simultaneous recording according to any one of claims 1 to 3 , wherein at least one of silica, titania, and alumina, or a plurality of them, is used in combination for the toner as an additive. Image forming method. An image forming method using a non-contact heat fixing method, wherein the toner used has a circularity of 0.93 or more and the melt viscosity at 140 ° C. of the toner is 120 mPas · sec or less. A single-sided single image forming method, wherein after-fixing by a contact heating fixing method, post-processing is performed with a heated pressure roller . 6. The single-sided single image forming method according to claim 5 , wherein a plurality of color toner images obtained by developing electrostatic latent images with different color toners are fixed after being superimposed on an image carrier. 7. The single-sided single image forming method according to claim 6 , wherein the toner images of yellow, magenta, cyan and black are fixed after being superimposed. The single-sided toner according to any one of claims 5 to 7, wherein at least one of silica, titania, and alumina, or a plurality thereof, is used in combination as an additive for the toner. Single image forming method.