JP2010181844A - Image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a forming method of an image exhibiting excellent smear resistance and good toner replenishing properties even after continuing printing for a long period to maintain high-quality images in the image forming method, wherein an image is formed at a printing speed of 45 m/min or higher and a recording medium carrying toner fixed by heat pressure fixing is treated by a post-treatment machine such as a finisher. <P>SOLUTION: The image forming method to form an image at a printing speed of 45 m/min or higher includes a process for post-treating the recording medium, to which toner is fixed by heat pressure fixing by the post-treatment machine. The toner consists of a toner mother particle and an external additive added to the toner mother particle externally. The toner mother particle contains a binder resin, a coloring agent, and 0.5-3.0 pts.wt. of a silicone oil for 100 pts.wt. of the binding resin. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming method using toner used for developing a latent image formed in an electrophotographic method, an electrostatic recording method, an electrostatic printing method or the like.

  In Patent Document 1, the gloss, transparency, and blocking properties are good, and the fixing phenomenon does not cause an offset phenomenon or a sheet wrapping phenomenon when toner is fixed by a heating roll fixing method that does not supply an anti-offset liquid such as silicone oil. For the purpose of providing a full-color toner for developing an electrostatic charge image having a wide temperature range and good fixability, an electrophotographic color toner containing at least a binder resin, an additive, a colorant, and a charge control agent is used. There is disclosed a full color toner for electrophotography, which is a polyester resin having a softening point of 90 to 120 ° C., and the additives are fatty acid amide and silicone oil.

  Patent Document 2 discloses a toner for a copying machine or a printer using heat roll fixing, which is excellent in low-temperature fixing property, offset resistance, and blocking resistance, and excellent in fixing strength, gloss, and transparency to transfer paper. In order to provide an optimal toner for electrophotography, rice wax is composed mainly of a fluorine-containing vinyl copolymer and a low-melting crystalline compound, and 100 parts by weight of the fluorine-containing vinyl copolymer binder resin. Is disclosed using a toner resin composition containing 0.4 to 8 parts by weight, 0.1 to 2 parts by weight of carnauba wax, and 0.05 to 1 part by weight of silicone oil.

JP 2000-29242 A JP 2001-75310 A

  However, in Patent Documents 1 and 2, deterioration in image quality is caused when a fixed image is processed using a print processing machine (post-processing machine) such as a mail sealer, a burster, a folding machine, a booklet finisher, or a staple finisher. The toner replenishability has not been studied.

  An object of the present invention is an image forming method for forming an image at a printing speed of 45 m / min or more, in which a recording medium on which toner is fixed by thermal pressure fixing is processed using a post-processing machine such as a finisher. An object of the present invention is to provide an image forming method that is excellent in smear resistance and has a good toner replenishment property and can maintain a high-quality image even when printing is continued for a long time.

  The present invention includes an image forming method for forming an image at a printing speed of 45 m / min or more, including a step of post-processing a recording medium on which toner is fixed by thermal pressure fixing, using a post-processing machine, Comprises toner base particles and an external additive externally added to the toner base particles, and the toner base particles are 0.5 to 3.0 parts by weight with respect to 100 parts by weight of the binder resin, the colorant, and the binder resin. The present invention relates to an image forming method comprising silicone oil.

  An image forming method for forming an image at a printing speed of 45 m / min or more by the method of the present invention, wherein a recording medium on which toner is fixed by thermal pressure fixing is applied to a post-processing machine such as cutting or stacking of the recording medium In the image forming method to be used and post-processed, it is excellent in smear resistance, has good toner replenishment property and good fixing property even when printing is continued for a long time, and can maintain a high quality image.

  The present invention is an image forming method for forming an image at a printing speed of 45 m / min or more, and a recording medium on which toner is fixed by thermal pressure fixing is used by using a post-processing machine such as cutting or stacking the recording medium. The image forming method to be processed is characterized in that a toner comprising toner base particles containing a specific amount of silicone oil and an external additive is used. Generally, when creating a large amount of printed materials such as invoices, direct mails, notices, etc., if the recording medium (printed material) with toner fixed is processed by a post-processing machine such as cutting or stacking the recording medium, Mechanical stress is applied and the printing surface is rubbed, so that degradation (smear) of the printed image becomes a problem. In particular, a high-speed printer that forms an image at a printing speed of 45 m / min or more is subjected to stronger mechanical stress due to the speed, and further the smear resistance is deteriorated. However, in the present invention, an image forming method for forming an image at a printing speed of 45 m / min or more by using a toner containing a specific amount of silicone oil, wherein the toner is fixed by thermal pressure fixing. Even in an image forming method in which a post-processing machine such as a finisher is used, good smear resistance and print quality can be maintained over a long period of time. In addition, since toner is consumed in a short time in printing at a high speed for a long period of time, toner replenishment from the toner cartridge to the developing unit is particularly important, but the toner of the present invention is also excellent in toner replenishment.

  The toner used in the method of the present invention comprises a binder resin, a colorant, and toner base particles further containing the silicone oil and an external additive.

  Examples of the binder resin include polycondensation resins such as polyester, vinyl resins such as styrene-acrylic resins, epoxy resins, polycarbonates, polyurethanes, etc. Among these, from the viewpoint of printing stability, Polyester is preferred. The polyester content in the binder resin is preferably 90% by weight or more, and more preferably 95% by weight or more.

  The polyester is not particularly limited, and can be obtained by polycondensing a raw material monomer containing an alcohol component composed of a divalent or higher alcohol and a carboxylic acid component composed of a divalent or higher carboxylic acid compound.

  As the dihydric or higher alcohol, from the viewpoint of the storage stability of the toner, the formula (I):

(In the formula, RO and OR are oxyalkylene groups, R is an ethylene and / or propylene group, x and y represent the number of added moles of alkylene oxide, each being a positive number, and the sum of x and y. 1 to 16 is preferable, 1 to 8 is more preferable, and 1.5 to 4 is more preferable)
An alkylene oxide adduct of bisphenol A represented by The content of the alkylene oxide adduct of bisphenol A is preferably 50 mol% or more, more preferably 60 mol% or more, and further preferably 80 mol% or more in the alcohol component.

  Examples of the alkylene oxide adduct of bisphenol A represented by the formula (I) include polyoxyethylene-2,2-bis (4-hydroxyphenyl) propane and other ethylene oxide adducts having 2 carbon atoms, such as polyoxypropylene. Examples thereof include propylene oxide adducts having 3 carbon atoms such as -2,2-bis (4-hydroxyphenyl) propane.

  As alcohol components other than the alkylene oxide adduct of bisphenol A, ethylene glycol, 1,2-propylene glycol, 1,4-butanediol, neopentyl glycol, polyethylene glycol, polypropylene glycol, bisphenol A, hydrogenated bisphenol A, sorbitol , Pentaerythritol, glycerol, trimethylolpropane and the like.

  Examples of the divalent or higher carboxylic acid compound include adipic acid, fumaric acid, maleic acid, succinic acid (for example, n-dodecenyl succinic acid, isododecenyl succinic acid, n-dodecyl succinic acid, isooctenyl succinic acid, Aliphatic carboxylic acids such as succinic acid substituted with alkyl groups having 1 to 20 carbon atoms or alkenyl groups having 2 to 20 carbon atoms such as isooctyl succinic acid, phthalic acid, isophthalic acid, terephthalic acid, 1,2, 4-Benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid, aromatic carboxylic acids such as pyromellitic acid, anhydrides of these acids and lower alkyl (C1-3) esters, etc. Is mentioned. In addition, the acids as described above, anhydrides of these acids, and alkyl esters of the acids are collectively referred to as carboxylic acid compounds in this specification.

  The alcohol component may contain a monovalent alcohol, and the carboxylic acid component may contain a monovalent carboxylic acid compound as appropriate from the viewpoint of adjusting the molecular weight and improving the offset resistance of the toner.

  The condensation polymerization of the alcohol component and the carboxylic acid component can be performed, for example, in an inert gas atmosphere at a temperature of 180 to 250 ° C., but may be performed in the presence of an esterification catalyst, a polymerization inhibitor, or the like. preferable. Examples of esterification catalysts include dibutyltin oxide, titanium compounds, tin (II) compounds having no Sn—C bond, and the like. These may be used alone or in combination.

  In the present invention, the polyester may be a polyester modified to such an extent that the characteristics are not substantially impaired. Examples of the modified polyester include grafting and blocking with phenol, urethane, epoxy and the like by the methods described in JP-A-11-133668, JP-A-10-239903, JP-A-8-20636, and the like. Polyester.

  The softening point of the polyester is preferably 120 to 160 ° C, more preferably 130 to 155 ° C, from the viewpoint of toner durability. When the polyester is composed of two or more kinds, it is preferable that the weighted average value is within the above range.

  The glass transition point of the polyester is preferably from 50 to 85 ° C, more preferably from 55 to 80 ° C, from the viewpoint of toner storage stability. The acid value is preferably 0.5 to 40 mg KOH / g from the viewpoint of environmental stability of the toner. The glass transition point is a physical property peculiar to an amorphous resin, but the binder resin of the present invention may be a crystalline resin.

  As the colorant, all of dyes and pigments used as toner colorants can be used. Carbon black, black pigment, phthalocyanine blue, permanent brown FG, brilliant first scarlet, pigment green B, rhodamine- B base, Solvent Red 49, Solvent Red 146, Solvent Blue 35, Quinacridone, Carmine 6B, Isoindoline, Disazo yellow and the like can be used alone or in combination of two or more of the present invention. The toner may be either black toner or color toner. The content of the colorant is preferably 1 to 40 parts by weight and more preferably 3 to 10 parts by weight with respect to 100 parts by weight of the binder resin.

  As the silicone oil, straight silicone oil, modified silicone oil and the like can be used, but dimethyl silicone oil is preferable from the viewpoint of ensuring high gloss.

The viscosity of the silicone oil is a kinematic viscosity, in view of the mixing easiness of the powder, preferably 0.60~1000000mm ² / s, more preferably 0.65~5000mm ² / s, still in view of easy handling More preferably, it is 0.65-1000 mm < ² > / s, More preferably, it is 1-100 mm < ² > / s.

  The content of the silicone oil is 0.5 to 3.0 parts by weight, preferably 1.0 to 3.0 parts by weight, with respect to 100 parts by weight of the binder resin, from the viewpoint of smear resistance of the image and charging stability of the toner. More preferably, it is 1.2-2.0 weight part.

  Toner raw materials other than binder resins, colorants and silicone oils include charge control agents, mold release agents, magnetic powders, conductivity modifiers, extender pigments, reinforcing fillers such as fibrous substances, antioxidants, and anti-aging agents. An additive such as an agent can be mentioned.

  As the charge control agent, any one of negative chargeability and positive chargeability can be used. Examples of the negatively chargeable charge control agent include metal-containing azo dyes, copper phthalocyanine dyes, metal complexes of salicylic acid alkyl derivatives, polymers of phenols and aldehydes such as nitroimidazole derivatives and calixarene, and the like. Examples of the positively chargeable charge control agent include nigrosine dyes, triphenylmethane dyes, quaternary ammonium salt compounds, polyamine resins, and imidazole derivatives. Also, a polymer type such as a resin can be used. The content of the charge control agent is preferably 0.1 to 8 parts by weight and more preferably 0.2 to 5 parts by weight with respect to 100 parts by weight of the binder resin.

  As the release agent, low molecular weight polypropylene, low molecular weight polyethylene, low molecular weight polypropylene polyethylene copolymer, aliphatic hydrocarbon waxes such as microcrystalline wax, paraffin wax, Fischer-Tropsch wax and their oxides, carnauba wax, Examples include ester waxes such as montan wax, sasol wax and their deoxidized wax, fatty acid amides, fatty acids, higher alcohols, fatty acid metal salts and the like. Among these, aliphatic hydrocarbon waxes and ester waxes are preferable from the viewpoint of releasability and stability, and these may be contained alone or in admixture of two or more. The content of the release agent is preferably 1 to 20 parts by weight and more preferably 1 to 10 parts by weight with respect to 100 parts by weight of the binder resin.

  The weight ratio of the silicone oil to the release agent content (silicone oil / release agent) is preferably from 0.5 to 10, more preferably from 0.7 to 3, and even more preferably from 1.5 to 2.5, from the viewpoint of image smear.

  The method for producing the toner base particles may be any known method such as a kneading and pulverizing method, an emulsification phase inversion method, and a polymerization method, but the kneading and pulverizing method is preferred because it is easy to produce. For example, in the case of a pulverized toner by a kneading and pulverizing method, a binder resin, a colorant, and the like are uniformly mixed with a mixer such as a Henschel mixer, and then melt-kneaded with a hermetic kneader or a uniaxial or biaxial extruder. It can be produced by cooling, pulverization and classification. A toner is obtained by externally adding an external additive to the obtained toner base particles. Silicone oil is preferably kneaded at the same time as the raw material of the toner base particles such as binder resin and colorant, and may be added when the raw material is premixed or added little by little from the raw material supply port during melt kneading May be.

  Examples of the external additive include inorganic fine particles such as silica, alumina, titanium oxide, zirconia, tin oxide, and zinc oxide, and organic fine particles such as resin fine particles. These surfaces have been subjected to hydrophobic treatment. Also good.

  The content of the external additive is preferably 0.1 to 1.0 part by weight, more preferably 0.3 to 0.8 part by weight, and more preferably 0.3 to 0.5 part by weight with respect to 100 parts by weight of the toner base particles from the viewpoint of charging stability and fluidity. Is more preferable.

  As the mixer used for mixing the toner base particles and the external additive, a high-speed stirrer such as a Henschel mixer or a super mixer, or a stirrer used for dry mixing such as a V-type blender is preferable. The external additives may be mixed in advance and added to a high-speed stirrer or a V-type blender, or may be added separately.

The volume median particle diameter (D ₅₀ ) of the toner is preferably 3 to 15 μm, more preferably 4 to 10 μm. In the present specification, the volume-median particle size (D ₅₀ ) means a particle size at which the cumulative volume frequency calculated by the volume fraction is 50% when calculated from the smaller particle size.

  A known fixing machine can be used for heat pressure fixing, but a heat roll is preferably used. In the heat pressure fixing, a heat roll adjusted so that the surface temperature of the heat roll is preferably 170 to 230 ° C., more preferably 180 to 230 ° C., from the viewpoint of fixability, offset resistance and the life of the fixing roll. It is desirable to use it.

  Further, from the viewpoint of fixing toner more efficiently, it is preferable to use a fixing device provided with a preheating mechanism for preheating a recording medium such as paper before the thermal pressure fixing. The preheating mechanism is not particularly limited as long as it can be installed in front of the fixing machine, and examples thereof include a preheating platen.

  In the preheating mechanism, the surface temperature of the preheating is preferably adjusted to 40 ° C. or more, more preferably 45 to 120 ° C., and further preferably 50 to 120 ° C. from the viewpoint of fixability.

  The post-processing machine is a processing machine that applies mechanical stress to the surface of the printed matter, and includes a processing machine having a recording medium cutting means, folding means, bookbinding means, gluing means, stacking means, etc. Can be mentioned. Among these, the effect of the present invention is more remarkably exhibited when a processing machine having a recording medium cutting means and a stacking means is used in that mechanical stress is applied to the surface of the printed matter. The cutting means is an apparatus that forms an image on a recording medium made of roll paper and then cuts the recording medium into a predetermined size. The stacking means is an apparatus that stacks the recording media cut by the cutting means. is there.

  As the printing speed increases, the recording medium is subjected to stronger mechanical stress due to the speed, and smearing is likely to occur. However, in the present invention, smearing can be effectively suppressed even when image formation is performed at a printing speed of 45 m / min or more, and further 50 to 150 m / min. Here, the printing speed refers to a paper feed speed for printing per unit time.

  The image forming method of the present invention can form an image through a known process except that it has features in a fixing process for fixing the transferred toner image to a recording medium and a subsequent processing process. As a process in the image forming method, in addition to the fixing process, for example, a process of forming an electrostatic latent image on the surface of the photoreceptor (charging / exposure process), a process of developing the electrostatic latent image (developing process), and developed toner There are a step of transferring an image to a transfer material such as paper (transfer step), a step of removing toner remaining on a developing member such as a photosensitive drum (cleaning step), and the like.

[Softening point of resin]
Using a flow tester (Shimadzu Corporation, CFT-500D), a 1 g sample is heated at a heating rate of 6 ° C / min. While applying a load of 1.96 MPa with a plunger and extruded from a nozzle with a diameter of 1 mm and a length of 1 mm. . Plot the plunger drop amount of the flow tester against the temperature, and let the softening point be the temperature at which half of the sample flows out.

[Glass transition point of resin]
Using a differential scanning calorimeter (Seiko Denshi Kogyo Co., Ltd., DSC210), the sample was heated to 200 ° C at a rate of 10 ° C / min and cooled to 0 ° C at a rate of 10 ° C / min. Start measurement at / min. The glass transition point is defined as the temperature at the intersection of the base line extension below the glass transition point and the tangent that indicates the maximum slope from the peak rising portion to the peak apex.

[Acid value of the resin]
Measured by the method of JIS K0070. However, only the measurement solvent was changed from the mixed solvent of ethanol and ether specified in JIS K0070 to the mixed solvent of acetone and toluene (acetone: toluene = 1: 1 (volume ratio)).

[Viscosity of silicone oil]
The viscosity is measured according to JIS Z8803 using a Canon Fenceke viscometer and kinematic viscosity (mm ² / s) in a constant temperature bath at 25 ° C.

[Volume-median particle size of toner (D ₅₀ )]
In this specification, the volume-median particle size (D ₅₀ ) of the toner means the particle size of the toner in which the cumulative volume frequency calculated by the volume fraction is 50% calculated from the smaller particle size.
Measuring instrument: Coulter Multisizer II (Beckman Coulter, Inc.)
Aperture diameter: 50μm
Analysis software: Coulter Multisizer AccuComp version 1.19 (Beckman Coulter)
Electrolyte: Isoton II (Beckman Coulter)
Dispersion: Emulgen 109P (manufactured by Kao Corporation, polyoxyethylene lauryl ether, HLB: 13.6) 5% by weight Electrolyte dispersion condition: 10 mg of measurement sample was added to 5 mL of dispersion, and dispersed for 1 minute with an ultrasonic disperser. Thereafter, 25 mL of an electrolytic solution is added, and further dispersed with an ultrasonic disperser for 1 minute.
Measurement conditions: The dispersion is added to 100 mL of the electrolytic solution so that the particle size of 30,000 toner particles can be measured in 20 seconds, and 30,000 particles are measured. Determine the median particle size (D ₅₀ ).

[Carrier saturation magnetization]
(1) Fill a plastic case with a lid of 7 mm outer diameter (6 mm inner diameter) and 5 mm height while tapping the carrier, and calculate the mass of the carrier from the difference between the weight of the plastic case and the weight of the plastic case filled with the carrier. .
(2) Set the plastic case filled with carrier in the sample holder of the magnetic property measuring device “BHV-50H” (VSMAGNETOMETER) of RIKEN ELECTRONICS CO., LTD., While vibrating the plastic case using the vibration function, Saturation magnetization is measured by applying a magnetic field of 79.6 kA / m. Using the mass of the filled carrier, the obtained value is converted into saturation magnetization per unit mass.

Resin production example 1
Polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane 2450 g, Polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane 975 g, terephthalic acid 963 g, dodecenyl succinic acid 343 g, 298 g of trimellitic anhydride and 10 g of dibutyltin oxide were placed in a 5 liter four-necked flask equipped with a nitrogen inlet tube, dehydrating tube, stirrer and thermocouple, and the reaction rate was 90% at 230 ° C in a nitrogen atmosphere. Then, the reaction was carried out at 8.3 kPa until the desired softening point was reached to obtain a polyester (resin A). The obtained resin A had a softening point of 147.5 ° C., a glass transition point of 63.0 ° C., and an acid value of 5.7 mgKOH / g. The reaction rate (%) refers to the value of the amount of reaction water produced / theoretical product water amount × 100.

Resin production example 2
Polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane (2800 g), terephthalic acid (1361 g), and dibutyltin oxide (10 g) were added to a 5-liter volume equipped with a nitrogen inlet tube, a dehydrating tube, a stirrer and a thermocouple. The mixture was placed in a four-necked flask and reacted under a nitrogen atmosphere at 230 ° C. until the reaction rate reached 90%, and then reacted at 8.3 kPa for 1 hour. Thereafter, the mixture was cooled to 210 ° C., 346 g of trimellitic anhydride was added, reacted at normal pressure for 1 hour, and then reacted until reaching the desired softening point at 8.3 kPa to obtain polyester (resin B). . The obtained resin B had a softening point of 146.8 ° C., a glass transition point of 73.4 ° C., and an acid value of 23.9 mgKOH / g.

Resin production example 3
3812 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 35 g of polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 546 g of terephthalic acid, and 10 g of dibutyltin oxide Was placed in a 5-liter four-necked flask equipped with a nitrogen inlet tube, a dehydrating tube, a stirrer, and a thermocouple, reacted under a nitrogen atmosphere at 230 ° C. until the reaction rate reached 90%, and then brought to 8 kPa. For 1 hour. After cooling to 185 ° C., 826 g of fumaric acid and 2.4 g of tertiary butyl catechol were added, reacted to 210 ° C. over 4 hours, then reacted at 8.0 kPa until the desired softening point was reached. (Resin C) was obtained. The obtained resin C had a softening point of 104.3 ° C., a glass transition point of 60.2 ° C., and an acid value of 11.4 mgKOH / g.

Resin production example 4
882 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 2594 g of polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 1551 g of terephthalic acid, and 10 g of dibutyltin oxide Was placed in a 5-liter four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple, reacted at 230 ° C. in a nitrogen atmosphere until the reaction rate reached 90%, and then 8.3 kPa. The polyester (resin D) was obtained by carrying out the reaction until the desired softening point was reached. The obtained resin D had a softening point of 106.4 ° C., a glass transition point of 64.8 ° C., and an acid value of 3.6 mgKOH / g.

Resin production example 5
Put 2,407 g of 1,6-hexanediol, 2320 g of fumaric acid, 2.5 g of hydroquinone, and 10 g of dibutyltin oxide in a 5-liter four-necked flask equipped with a nitrogen inlet tube, dehydration tube, stirrer, and thermocouple, and put in a nitrogen atmosphere. Then, after reacting by raising the temperature from 130 ° C. to 160 ° C. over 4 hours, 400 g of polypropylene wax “NP105” (manufactured by Mitsui Chemicals) is added, and the temperature is raised to 200 ° C. over 3 hours. Was reacted for 30 minutes at 8 kPa until the desired softening point was reached at 8 kPa to obtain a crystalline polyester (resin a). The obtained resin a had a softening point of 120.3 ° C. and a melting point (DSC endothermic peak) of 111.5 ° C.

Examples 1-8 and Comparative Examples 1-3
The toner raw materials shown in Table 1 were premixed using a Henschel mixer, then melt-kneaded, cooled and coarsely pulverized with a twin-screw extruder, then pulverized and classified with a jet mill to obtain a volume-median particle size (D ₅₀ ) To obtain toner base particles of 10 μm.

  To 100 parts by weight of the obtained toner base particles, 0.35 part by weight of positively charged hydrophobic silica “HDK3050VP” (manufactured by Clariant) was added as an external additive, and mixed with a Henschel mixer to obtain a toner.

Toner and a ferrite carrier (average particle size: 110 μm) coated with fluorine / acrylic resin and having a saturation magnetization of 60 Am ² / kg are mixed in a V-type blender, and a two-component developer with a toner concentration of 3.5% by weight is mixed. Obtained.

Test Example 1 [Print quality and toner replenishment property]
Toner and two-component developer, Infoprint 4100 HS2 printing system (printing speed 53.34m / min, "Lasermax Roll Systems" RSU4 Unwinder (roll paper feeder) + Infoprint4100 HS2 + "Lasermax Roll Systems" RSSM2 Slit / Nerge + Set to RSC8 Cutter + RSV3 Stacker (stacking device: cutting / trimming / stacking device)), print 100 feet at contrast 4 and post-processing (cut / trimming / stacking), then print sample for print quality confirmation Collected. Next, after printing 100,000 feet at contrast 4, print samples for print quality confirmation were collected again, and the image density (OD) of 100 feet and 100,000 feet of black solid area was set to `` X-Rite '' (X-Rite) ). From both image density ratios, the print quality was evaluated according to the following evaluation criteria. In addition, the set temperature of the preheat equipped with the preheating platen was adjusted to 60 ° C, the surface temperature of the heat roll was adjusted to 190 ° C, respectively, and HSP-G paper (high quality) manufactured by IBM Japan was used as the printing paper. .

[Evaluation criteria for print quality]
A: OD (100,000 feet) / OD (100 feet) is 0.7 or more B: OD (100,000 feet) / OD (100 feet) is less than 0.7

  Furthermore, after filling the toner cartridge with 3 kg of the toner and shaking it 20 times, mount the cartridge on the printer, replenish the toner according to the printer manual, and after the replenishment procedure, check the inside of the cartridge and all the toner is The toner replenishability was visually confirmed according to the following evaluation criteria depending on whether or not it was put in the hopper. The results are shown in Table 1.

[Evaluation criteria for toner replenishment]
A: No toner remaining in the cartridge B: Some toner remaining in the cartridge is confirmed

Test Example 2 [Smear evaluation]
Print sample of the SUTHERLAND (registered trademark) Ink Rub Tester with toner and two-component developer printed on the Infoprint 4100 HS2 printing system at contrast 7 and post-processed (cut / trimmed / stacked) (line thickness 0.5) Set `` L '' in mm on the entire surface of the paper at a density of 15 pieces per 1 cm x 1 cm), set the print side up, rub it 20 times with filter paper, and then color difference meter `` X-Rite '' (X-Rite Y value was measured by a company, and the degree of dirt on the filter paper was measured. The results are shown in Table 1.

Test Example 3 [Fixability evaluation]
Nichiban Co., Ltd.'s cello tape (registered trademark) “CT-” is printed on the black solid part of the print sample in which the toner and two-component developer are printed and post-processed (cut / trimmed / stacked) with contrast 7 using the Infoprint 4100 HS2 printing system. 24 '' and rubbed the tape surface 20 times with a 450g heavy metal column with a bottom area of 3cm x 3cm, then slowly peeled off the tape, and the image density before and after rubbing was set to `` X-Rite '' (manufactured by X-Rite) The change rate (Y value after tape peeling / Y value before tape application × 100) was calculated. The results are shown in Table 1.

  From the above results, it can be seen that in Examples 1 to 8, both the smear resistance and the fixing property are good, and the print quality and the toner replenishability are not problematic. On the other hand, in Comparative Example 1 using a toner containing no silicone oil, the fixing property and smear resistance are significantly reduced, and Comparative Example 2 using a toner having a silicone oil content less than a predetermined amount. Then, it lacks smear resistance. In Comparative Example 3 using a toner containing a predetermined amount or more of silicone oil, the fixability and the smear resistance are good, but the toner replenishment property and the print quality are lacking.

  The image forming method of the present invention is suitably used for developing a latent image formed in electrophotography, electrostatic recording method, electrostatic printing method and the like.

Claims (3)

  An image forming method for forming an image at a printing speed of 45 m / min or more, comprising a step of post-processing a recording medium on which toner has been fixed by thermal pressure fixing with a post-processing machine, wherein the toner is toner base particles And an external additive externally added to the toner base particles, the toner base particles containing a binder resin, a colorant, and 0.5 to 3.0 parts by weight of silicone oil with respect to 100 parts by weight of the binder resin. An image forming method.   The image forming method according to claim 1, wherein the thermal pressure fixing is performed by a heat roll adjusted so that the surface temperature is 170 to 230 ° C.   The image forming method according to claim 1, wherein the post-processing device includes a recording medium cutting unit and a recording medium stacking unit.