Image formation methods

Abstract

The object of the present invention is to provide an image forming method that ensures separation from the fuser without reducing the amount of release agent on the image surface, even when image formation is performed using a continuous-form printing press, and that offers excellent post-processing capabilities. Furthermore, the object of the present invention is to provide an image forming method that is also excellent in terms of high speed and low-temperature fixing in a continuous-form printing press. [Solution] The present invention is an image forming method for forming a toner image on a continuous-print medium using toner, wherein the area ratio of elements derived from inorganic fine particles to the total area of ​​elements measured by X-ray photoelectron spectroscopy (ESCA) of the toner image is in the range of 4 to 10%, and the toner has toner matrix particles, and the toner matrix particles contain a release agent and an amorphous polyester.

Description

Technical Field

[0001] The present invention relates to an image forming method, and particularly to an image forming method that ensures separability from a fixing device and has excellent post-processing properties without reducing the amount of a release agent on the image surface.

Background Art

[0002] In recent years, due to the diversification of printing media and the improvement of the added value of images, electrophotographic printing on printing media other than paper has been demanded. For example, a continuous media such as roll paper or continuous forms is conveyed in a roll-to-roll manner, and an image is formed on the conveyed continuous media by an image forming apparatus. As a toner suitable for continuous media, for example, in Patent Document 1, a toner containing fine particles of polypropylene-based wax is disclosed.

[0003] By the way, labels and seals output by a continuous printer on continuous media are frequently post-processed by varnish or lamination. Therefore, the output image by a continuous printer is required to have improved post-processing properties such as varnish coating property and lamination adhesion property as compared with the output image by a sheet-fed printer.

[0004] However, printing materials used for forming an image on continuous media contain a release agent such as wax in order to ensure separability from a fixing device. Therefore, the release agent repels varnish and adhesives, and the post-processing properties are insufficient. In recent years, high speed and low temperature fixing properties have also been demanded in continuous printers, and it has been difficult to ensure both high speed and low temperature fixing properties and separation performance in these continuous printers.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

[0006] This invention has been made in view of the above-mentioned problems and circumstances. The problem to be solved by this invention is to provide an image forming method that ensures separation from the fuser without reducing the amount of release agent on the image surface, even when image formation is performed using a continuous-form printing press, and that offers excellent post-processing properties. Furthermore, the problem to be solved by this invention is to provide an image forming method that is also excellent in terms of high speed and low-temperature fixing in a continuous-form printing press. [Means for solving the problem]

[0007] The inventors investigated the causes of the above problems in order to solve them. The inventors set the area ratio of elements derived from inorganic fine particles to the total area of ​​all elements measured by X-ray photoelectron spectroscopy (ESCA) of the toner image to a specific range, and made the toner matrix particles contain a release agent and amorphous polyester. As a result, they found that it is excellent in terms of separation from the fuser and post-processing, as well as in high-speed continuous-feed printing and low-temperature fixing. In other words, the above-mentioned problems according to the present invention are solved by the following means.

[0008] 1. An image forming method for forming a toner image on a continuous-feed medium using toner, The area ratio of elements derived from inorganic fine particles to the total area of ​​all elements measured by X-ray photoelectron spectroscopy (ESCA) of the aforementioned toner image is within the range of 4-10%. The toner has toner matrix particles, The toner matrix particles contain a release agent and amorphous polyester. A method for forming an image characterized by the following features.

[0009] 2. The element derived from the inorganic fine particles is Si or Ti. The image forming method according to paragraph 1, characterized in that

[0010] 3. The mold release agent is a hydrocarbon wax. The image forming method according to paragraph 1, characterized in that

[0011] 4. The content of the amorphous polyester is within the range of 10 to 50% by mass relative to the content of the toner matrix particles. The toner image containing white pigment is printed on top of the white toner image, The difference in softening point between the white toner containing the white pigment and the toner is 14°C or less. The image forming method according to any one of the first to third paragraphs, characterized by the above. [Effects of the Invention]

[0012] The above means of the present invention makes it possible to ensure separation from the fuser without reducing the amount of release agent on the image surface, even when image formation is performed using a continuous-feed printing press, and provides an image formation method with excellent post-processing properties. Furthermore, the above means also makes it possible to provide an image formation method that is excellent in terms of high speed and low-temperature fixing properties in a continuous-feed printing press. Although the mechanism of action or mechanism of the present invention is not yet clear, it is speculated as follows. By setting the area ratio of elements derived from inorganic microparticles to the total area of ​​all elements measured by X-ray photoelectron spectroscopy (ESCA) of the toner image to a range of 4-10%, the area ratio of elements derived from inorganic microparticles on the surface of the toner image becomes larger. In other words, the external additive does not become embedded in the image but protrudes from the image surface in a convex manner. As a result, the convex external additive protruding from the image surface causes the continuous-feed medium to make point contact with the external additive during fixing. Consequently, separation can be ensured regardless of the type or amount of release agent, even when using a high-speed continuous-feed printing press. Furthermore, in post-processing, for example, when varnish is applied, materials such as varnish can penetrate between the external additives. As a result, the surface area in contact with the varnish increases, ensuring good applicability and adhesion of the varnish, and resulting in superior post-processing performance. Furthermore, since the toner image is formed on the continuous sheet medium, it is preferable to convey it in a roll-to-roll manner and form a toner image on the conveyed continuous sheet medium using a continuous sheet printer. By using a continuous sheet printer with a roll-to-roll method, the continuous sheet medium is pulled downward immediately after fixing. Therefore, compared with the case of using a sheet-fed printer, the external additive is less likely to be buried in the image, and the amount of the external additive protruding from the image surface also increases.

Brief Description of the Drawings

[0013] [Figure 1] Figure showing an overall configuration example of the image forming apparatus according to the present embodiment [Figure 2] Figure showing a main part of the control system of the image forming apparatus

Embodiments for Carrying Out the Invention

[0014] The image forming method of the present invention is an image forming method for forming a toner image on a continuous sheet medium using toner, with respect to the area of all elements measured by X-ray photoelectron spectroscopy (ESCA) of the toner image, the area ratio of the elements derived from inorganic fine particles is within the range of 4 to 10%, the toner has toner mother particles, and the toner mother particles contain a release agent and an amorphous polyester. This feature is a technical feature common or corresponding to each of the following embodiments.

[0015] As an embodiment of the present invention, it is preferable that the element derived from the inorganic fine particles is Si or Ti because the hardness of the inorganic fine particles is an appropriate condition and a convex state suitable for the separability from the fixing device can be created.

[0016] It is preferable that the release agent is a hydrocarbon wax. Since the hydrocarbon wax has no polarity, it is likely to be arranged at the non-polar part of the resin on the image surface during fixing. Compared with ester wax, the hydrocarbon wax forms a dotted pattern on the image surface, so the varnish coating property as a post-treatment is improved.

[0017] The content of the amorphous polyester is in the range of 10 to 50% by mass with respect to the content of the toner base particles. The toner image is printed on a white toner image containing a white pigment, and it is preferable that the difference in softening point between the white toner containing the white pigment and the toner is 14°C or less. When printing a colored toner image on a white toner image containing a white pigment, the adhesion amount of the white toner may be increased to enhance the hiding power. At this time, since most of the thermal energy during fixing is used for the fixing of the white toner, the action at the interface between the white toner and the colored toner is important for ensuring the overall fixing property. By designing the difference in softening point between the white toner and the colored toner to be small and increasing the content of the amorphous polyester, which is advantageous for low-temperature fixing, in the colored toner, the compatibilizing effect between the white toner and the colored toner is enhanced, and the fixing property is improved.

[0018] Hereinafter, the present invention, its components, and the embodiments and modes for carrying out the present invention will be described. In the present application, "~" is used to mean including the numerical values described before and after it as the lower limit value and the upper limit value.

[0019] [Outline of the image forming method of the present invention] The image forming method of the present invention is an image forming method for forming a toner image on a continuous medium using toner, wherein the area ratio of the elements derived from inorganic fine particles is in the range of 4 to 10% with respect to the area of all elements measured by X-ray photoelectron spectroscopy (ESCA) of the toner image, and the toner contains a release agent and an amorphous polyester. The toner is preferably a colored toner containing a coloring agent. Furthermore, the image forming method of the present invention involves printing a colored toner image on top of a white toner image containing a white pigment, and it is preferable that the difference in softening points between the white toner containing the white pigment and the colored toner is 14°C or less. In the following description, toner containing a colored pigment will also be referred to as "colored toner" or simply "toner." Toner containing a white pigment will also be referred to as "white toner." In this invention, when simply referred to as "toner," it means colored toner.

[0020] <Area ratio of elements derived from inorganic microparticles> The area ratio of elements derived from inorganic fine particles to the total area of ​​all elements measured by X-ray photoelectron spectroscopy (ESCA) of the toner image is within the range of 4 to 10%. A range of 4.5 to 8% is preferable from the viewpoint of achieving both good fixation separation and post-processing properties.

[0021] In this invention, "elements derived from inorganic fine particles" refers to inorganic elements contained in inorganic fine particles. "Inorganic fine particles" refers to fine particles containing metal elements, and in this invention, it is particularly preferable that these are inorganic fine particles added as an external additive.

[0022] Preferably, the inorganic fine particles are metal oxide particles whose surface is composed of a metal oxide. Examples of metal oxides that constitute the inorganic fine particles are not particularly limited, but include aluminum oxide (alumina), silicon oxide (silica), magnesium oxide, zinc oxide, lead oxide, tin oxide, tantalum oxide, indium oxide, bismuth oxide, yttrium oxide, cobalt oxide, copper oxide, manganese oxide, selenium oxide, iron oxide, zirconium oxide, germanium oxide, tin oxide, titanium oxide (titania), niobium oxide, molybdenum oxide, vanadium oxide, copper-aluminum oxide, and tin oxide doped with antimony ions. These inorganic fine particles can be used individually or in combination of two or more types.

[0023] Among these inorganic fine particles, it is preferable that they be aluminum oxide particles, tin oxide particles, titanium oxide particles, or silicon oxide particles (silica particles), and more preferably titanium oxide particles or silicon oxide particles. In the present invention, the elements derived from inorganic fine particles are preferably silicon, titanium, or aluminum, and are more preferably silicon or titanium.

[0024] In this invention, "all elements measured by ESCA of the toner image" refers to all elements contained in the toner material. In this invention, "all elements measured by ESCA of the toner image" preferably refers to, for example, carbon, oxygen, and elements derived from the inorganic fine particles.

[0025] X-ray photoelectron spectroscopy is performed using an X-ray photoelectron spectroscopy analyzer, such as the K-Alpha (manufactured by Thermo Fisher Scientific), under the following measurement conditions. This process identifies the peak areas of carbon (peak area C), oxygen (peak area O), and elements derived from inorganic fine particles that are present within 3 nm of the outermost surface of the toner particles. Examples of peak areas for elements derived from the inorganic fine particles include the peak area for silicon and the peak area for titanium. Each peak area is identified using a relative sensitivity factor from the respective atomic peak area. Then, from the obtained peak areas, the area ratio of elements derived from inorganic nanoparticles to the total area of ​​all elements is calculated based on equation A below. Formula A: (Total peak areas of elements derived from inorganic microparticles) / (Peak area C + Peak area O + Total peak areas of elements derived from inorganic microparticles) × 100 (Measurement conditions) X-ray: Al monochromatic source Acceleration: 12kV, 6mA Resolution: 50eV Beam system: 400 μm Pass energy: 50 eV Step size: 0.1eV

[0026] Even when a colored toner image is formed on top of a white toner image formed with white toner, the white toner image is formed beneath the colored toner image. Therefore, the elements measured by X-ray photoelectron spectroscopy are those contained in the colored toner image, not those contained in the white toner image. Consequently, even when a white toner image is formed beneath a colored toner image, the area ratio of the inorganic fine particle-derived elements is not affected by the white toner image, and the area ratio of the inorganic fine particle-derived elements in the colored toner image becomes the "area ratio of inorganic fine particle-derived elements" in this invention.

[0027] Means for setting the area ratio of elements derived from inorganic fine particles within the range of 4 to 10% include, for example, adjusting the amount of external additives added, the average particle size of the external additives, or the hardness of the toner matrix particle surface. Specifically, the amount of external additive added is preferably in the range of 0.05 to 5 parts by mass per 100 parts by mass of toner matrix particles. When titanium dioxide particles are used as the external additive, the number-average primary particle size of the titanium dioxide particles is preferably in the range of 60 to 120 nm. When silica particles are used as the external additive, the number-average primary particle size of the silica particles is preferably in the range of 10 to 120 nm. The method for measuring the number-average primary particle size will be described later. The hardness of the toner matrix particle surface can be controlled by adjusting the content of the chain transfer agent. When the content of the chain transfer agent is increased, the surface of the toner matrix particles becomes softer, and the inorganic fine particles, which are external additives, become more easily embedded in the formed image surface. As a result, the area ratio of elements derived from the inorganic fine particles decreases. On the other hand, when the content of the chain transfer agent is decreased, the surface of the toner matrix particles becomes harder, and the inorganic fine particles, which are external additives, become less easily embedded in the formed image surface. The amount of external additive protruding from the image surface increases, and the area ratio of elements derived from the inorganic fine particles increases. The amount of chain transfer agent added varies depending on the desired molecular weight and molecular weight distribution, but specifically, it is preferable to be in the range of, for example, 0.1 to 5.0% by mass relative to the polymerizable monomer.

[0028] <Image Formation> For forming toner images to be measured by X-ray photoelectron spectroscopy, the "AccurioLabel 400" (manufactured by Konica Minolta) is used as an image forming apparatus (continuous-feed printer) for continuous-feed media. A two-component developer is loaded into this apparatus. Image formation is performed using N-Mirror 73 / P22 / L8W (manufactured by Oji Tack Co., Ltd.) as the printing medium under normal temperature and humidity conditions (temperature 22°C, humidity 50%RH). The amount of toner deposited in the image before fixing is adjusted to match the amount of toner deposited in Table IV of the example described later. Then, the surface temperature of the fixing heating element is set to 200°C and the image is output. The above image forming apparatus for continuous-feed media is capable of high-speed printing, for example, at 20-40 m / min.

[0029] <Continuous book media> Examples of continuous forms used in this invention include continuous forms and roll paper. Continuous forms can be applied to roll-to-roll printing and processing technologies, thereby improving production efficiency. A continuous-print medium thickness of 75 μm or less is preferable in that it covers general-purpose recording media and allows for the acquisition of images without fixing defects. A continuous-print medium thickness within the range of 50 to 75 μm is more preferable. The continuous form medium is preferably transparent and flexible, and made of a resin such as polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE), or polyolefin (PO). The continuous-print medium may be a single layer or a multi-layer medium consisting of two or more layers joined together via an adhesive layer. The surface of the continuous-print medium may be untreated with corona treatment, plasma treatment, etc., but it is preferable to perform corona treatment or plasma treatment, etc., from the viewpoint of adhesion. In particular, in the present invention, it is preferable that the continuous sheet medium is a polyethylene terephthalate film with a thickness of 50 μm in terms of fixation and adhesion.

[0030] <Softening point> In the image forming method of the present invention, it is preferable that the difference in softening points between the white toner and the colored toner is 14°C or less. More preferably, the difference in softening points is within the range of 0 to 12°C. The difference in softening points (°C) can be calculated as the absolute value of the difference between the softening points (°C) of colored toner and white toner (softening point (°C) of colored toner - softening point (°C) of white toner). The softening points of colored toner and white toner can be measured, for example, by the following method: Using a flow tester "CFT-500D" (manufactured by Shimadzu Corporation), 1 g of sample is heated at a heating rate of 6 °C / min while a load of 1.96 MPa is applied by a plunger and the sample is extruded from a nozzle with a diameter of 1 mm and a length of 1 mm. The amount of plunger descent of the flow tester is plotted against the temperature, and the temperature at which half of the sample has flowed out is defined as the softening point.

[0031] The softening point of colored toner is preferably in the range of 80 to 120°C. The softening point of white toner is preferably in the range of 80 to 110°C.

[0032] [toner] The following describes the composition of toner (colored toner). In this specification, "toner" means toner for electrostatic latent image development. The toner includes toner particles comprising toner matrix particles and an external additive disposed on the surface of the toner matrix particles. "Toner matrix particles" are the constituent elements of "toner particles." These "toner matrix particles" are then referred to as "toner particles" after the addition of external additives. And "toner" refers to an aggregate of toner particles. A "toner image" refers to a state in which toner particles are clustered together in an image-like pattern.

[0033] The toner according to the present invention comprises toner matrix particles and an external additive. The toner matrix particles contain a release agent and an amorphous polyester. The toner matrix particles may also optionally contain other components such as binder resins, colorants, and charge control agents in addition to the amorphous polyester.

[0034] [Toner matrix particles] <Binding resin> The toner matrix particles according to the present invention contain amorphous polyester. The toner matrix particles may also contain a binder resin other than amorphous polyester. The inclusion of a binder resin in the toner matrix particles allows the toner to be fixed onto the continuous-feed medium. Examples of binder resins other than amorphous polyester include vinyl resins, urethane resins, urea resins, and crystalline resins. In the present invention, it is preferable to include vinyl resin and amorphous polyester resin as the binder resin.

[0035] In this invention, "amorphous" means that, in the endothermic curve obtained by differential scanning calorimetry (DSC), it has a glass transition temperature (Tg), but does not have a melting point, i.e., a clear endothermic peak during heating. A clear endothermic peak is defined as an endothermic peak with a full width at half maximum of 15°C or less in the endothermic curve when heated at a heating rate of 10°C / min.

[0036] Amorphous polyester From the viewpoint of low-temperature fixation, the toner matrix particles according to the present invention contain amorphous polyester. "Amorphous polyester" refers to a polyester that exhibits amorphous properties, obtained by the polycondensation reaction of a divalent or higher carboxylic acid (polycarboxylic acid) monomer and a divalent or higher alcohol (polyhydric alcohol) monomer. Amorphous polyester can be synthesized by polycondensing (esterifying) the above-mentioned polycarboxylic acid monomer and polyhydric alcohol monomer using a known esterification catalyst.

[0037] Polycarboxylic acids are compounds that contain two or more carboxyl groups in a single molecule. Examples of polycarboxylic acids include phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, naphthalene-2,6-dicarboxylic acid, malonic acid, mesaconic acid, dimethyl isophthalate, fumaric acid, dodecenyl succinic acid, and 1,10-dodecanedicarboxylic acid. Among these, dimethyl isophthalate, terephthalic acid, dodecenyl succinic acid, or trimellitic acid are preferred. These may be present individually or in combination of two or more types.

[0038] Polyhydric alcohols are compounds that contain two or more hydroxyl groups in a single molecule. Examples of polyhydric alcohols include dihydric alcohols such as ethylene glycol, propylene glycol, butanediol, diethylene glycol, pentanediol, neopentyl glycol, hexanediol, heptanediol, cyclohexanediol, octanediol, decanediol, and dodecanediol; trihydric or higher polyols such as glycerin, pentaerythritol, hexamethylolmelamine, hexaethylolmelamine, tetramethylolbenzoguanamine, and tetraethylolbenzoguanamine; and ester compounds thereof; and hydroxycarboxylic acid derivatives. These may be present individually or in combination of two or more types.

[0039] Furthermore, from the viewpoint that bisphenols, like alcohols, can be esterified, the present invention includes bisphenol A or a bisphenol A derivative in the above-mentioned "polyhydric alcohol". Examples of bisphenol A derivatives include ethylene oxide adducts of bisphenol A (BPA-EO) and propylene oxide adducts of bisphenol A (BPA-PO).

[0040] In particular, the polyhydric alcohol is preferably an aliphatic polyhydric alcohol or an alicyclic polyhydric alcohol. Especially, the polyhydric alcohol is preferably an acyclic aliphatic polyhydric alcohol having 5 or more carbon atoms, and most preferably an aliphatic polyhydric alcohol having 5 to 7 carbon atoms. Aliphatic polyhydric alcohols with 5 to 7 carbon atoms have a relatively small bulk, making it easier to achieve uniform ester bond distances in the resulting polyesters. Furthermore, regions with a high density of ester groups are less likely to form locally. Specifically, it is thought that the hydrophilic sites derived from ester bonds and the hydrophobic sites derived from hydrocarbon groups are appropriately dispersed, thereby suppressing charge leakage.

[0041] In particular, aliphatic polyhydric alcohols with 5 to 7 carbon atoms have a smaller bulk compared to bisphenol A or bisphenol A derivatives. Therefore, it is thought that aliphatic polyhydric alcohols with 5 to 7 carbon atoms can suppress charge leakage compared to bisphenol A or bisphenol A derivatives.

[0042] Examples of aliphatic polyhydric alcohols with 5 to 7 carbon atoms include pentanediol, neopentyl glycol, hexanediol, heptanediol, or cyclohexanediol.

[0043] From the viewpoint of suppressing charge leakage, it is preferable that the proportion of bisphenol A or bisphenol A derivatives in the polyhydric alcohol be low. In this invention, the content of structural units derived from bisphenol A or bisphenol A derivatives relative to the total number of moles of structural units derived from polyhydric alcohols is 10 mol% or less. This is thought to suppress charge leakage and reduce unevenness in the density of the formed image.

[0044] The content of structural units derived from bisphenol A or bisphenol A derivatives relative to the total number of moles of structural units derived from polyhydric alcohols is preferably lower. Specifically, it is preferably 5 mol% or less, and more preferably 1 mol% or less. Furthermore, the structural units derived from polyhydric alcohols do not necessarily have to contain any structural units derived from bisphenol A or bisphenol A derivatives.

[0045] Examples of esterification catalysts include alkali metal compounds such as sodium and lithium; alkaline earth metal compounds such as magnesium and calcium; metal compounds such as aluminum, zinc, manganese, antimony, titanium, tin, zirconium, and germanium; phosphite compounds; phosphate compounds; and amine compounds.

[0046] The polymerization temperature is not particularly limited, but is preferably in the range of 150 to 250°C. The polymerization time is also not particularly limited, but is preferably in the range of 0.5 to 10 hours. During polymerization, the reaction system may be subjected to reduced pressure as needed.

[0047] The amorphous polyester content is preferably in the range of 5 to 80% by mass, and more preferably in the range of 10 to 50% by mass, relative to the total mass of the binder resin. Furthermore, the amorphous polyester content is preferably 10% by mass or more, and more preferably 40% by mass or more, relative to the total mass of the toner matrix particles.

[0048] Hybrid amorphous polyester Amorphous polyester may also be a hybrid crystalline polyester in which amorphous polyester polymerization segments and amorphous polymerization segments other than amorphous polyester are chemically bonded together.

[0049] Vinyl resin Vinyl resin is a resin obtained by polymerization using at least vinyl monomers. Examples of amorphous vinyl resins include acrylic resins and styrene-acrylic resins. Among these, styrene-acrylic resins formed using styrene monomers and (meth)acrylic acid ester monomers are preferred as amorphous vinyl resins. Specific examples of styrene monomers and (meth)acrylic acid ester monomers capable of forming styrene-acrylic resins are shown below. However, the materials that can be used to form the styrene-acrylic resins used in the present invention are not limited to those shown below.

[0050] (Styrene monomers) Examples of styrene monomers include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, and their derivatives. These styrene monomers can be used individually or in combination of two or more.

[0051] ((meth)acrylic acid ester monomers) Examples of (meth)acrylic acid ester monomers include acrylic acid ester monomers such as methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, and phenyl acrylate; and methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, and dimethylaminoethyl methacrylate.

[0052] The styrene-acrylic resin content is preferably 70% by mass or more relative to the total amount of the binder resin. Within this range, the effect of improving electrostatic properties can be sufficiently achieved.

[0053] In addition to the above, a third polymerizable monomer can also be used. Examples of this third polymerizable monomer include acid monomers such as acrylic acid, methacrylic acid, maleic anhydride, and vinyl acetic acid. Other examples of this third polymerizable monomer include acrylamide, methacrylamide, acrylonitrile, ethylene, propylene, butylene vinyl chloride, N-vinylpyrrolidone, and butadiene. As a third polymerizable monomer, a polyfunctional vinyl monomer may also be used. Examples of polyfunctional vinyl monomers include diacrylates of ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, etc., and dimethacrylates and trimethacrylates of tertiary or higher alcohols such as divinylbenzene, pentaerythritol, and trimethylolpropane.

[0054] The method for producing styrene-acrylic resin is not particularly limited, and examples include known polymerization methods such as bulk polymerization, solution polymerization, emulsion polymerization, miniemulsion polymerization, and dispersion polymerization. Furthermore, any polymerization initiator commonly used for the polymerization of the above monomers, such as peroxides, persulfides, persulfates, and azo compounds, can be used in the above production method. Furthermore, commonly used chain transfer agents can be used to adjust the molecular weight. The chain transfer agents are not particularly limited and include, for example, alkyl mercaptans such as n-octyl mercaptan, mercapto fatty acid esters, and the like. Furthermore, the content of the chain transfer agent is preferably in the range of, for example, 0.1 to 5.0% by mass relative to the polymerizable monomer, as described above. By adjusting the content of the chain transfer agent, the hardness of the resin can be controlled, and the hardness of the toner matrix particle surface can be controlled. This allows the area ratio of elements derived from inorganic fine particles to be controlled within the range of 4 to 10%.

[0055] Glass transition temperature From the viewpoint of achieving both sufficient low-temperature fixation and heat-resistant storage, the glass transition temperature (Tg) of the amorphous resin is preferably in the range of 30 to 70°C, and more preferably in the range of 40 to 65°C.

[0056] For example, differential scanning calorimetry (DSC measurement) is performed using a differential scanning calorimeter "DSC7000X" (manufactured by HITACHI) and a thermal analysis device controller "AS3 / DX" (manufactured by HITACHI). Specifically, 5 mg of the sample is sealed in an AL autosampler sample container φ6.8 H2.5 mm (manufactured by HITACHI) and an AL autosampler cover (manufactured by HITACHI). This is then placed in the sample holder of the "AS3 / DX," and the temperature is varied in the order of heating, cooling, and heating. During the first and second heating cycles, the temperature is raised from 0°C to 150°C at a heating rate of 10°C / min and held at 150°C for 1 minute. During cooling, the temperature is lowered from 150°C to 0°C at a cooling rate of 10°C / min and held at 0°C for 1 minute. The baseline shift is observed in the measurement curve obtained during the second heating cycle. The glass transition temperature (Tg) is defined as the intersection of the extension of the baseline before the shift and the tangent line representing the maximum slope of the shifted portion of the baseline. An empty aluminum pan is used as a reference.

[0057] Crystalline resin The toner matrix particles according to the present invention may contain a crystalline resin. By including a crystalline resin, the crystalline portion melts when the crystalline resin exceeds its melting point, and the crystalline resin and amorphous polyester become compatible, thereby improving low-temperature fixability.

[0058] In this invention, "exhibiting crystallinity" means that, in the endothermic curve obtained by DSC (Differential Scanning Calorimetry), there is a clear endothermic peak at the melting point, i.e., when heating increases, rather than a stepwise endothermic change. A clear endothermic peak is defined as a peak with a full width at half maximum of 15°C or less in the endothermic curve when heating at a heating rate of 10°C / min.

[0059] As the crystalline resin, it is preferable to use known crystalline resins, such as crystalline polyester or crystalline polyurethane. In particular, crystalline polyester is preferred from the viewpoint of sharp melt during melting and compatibility with the binder resin. That is, it is preferable that the parts having a crystalline structure contain crystalline polyester. The content of the crystalline polyester is preferably in the range of 0.1 to 15% by mass relative to the total mass of the binder resin.

[0060] Crystalline polyester "Crystalline polyester" refers to known polyesters that exhibit crystalline properties, obtained by a polycondensation reaction between a divalent or higher carboxylic acid (polycarboxylic acid) and a divalent or higher alcohol (polyhydric alcohol).

[0061] Crystalline polyesters preferably have structural units derived from aliphatic diols and structural units derived from aliphatic carboxylic acids. Furthermore, it is preferable that they have only structural units derived from aliphatic diols and structural units derived from aliphatic carboxylic acids.

[0062] The number of carbon atoms in an aliphatic diol or aliphatic carboxylic acid is within the range of 6 to 10. This is more preferable. By making the crystalline polyester a relatively low-bulk structure, it is thought that the localized high density of ester groups can be suppressed, thereby suppressing charge leakage.

[0063] Polycarboxylic acids are compounds that contain two or more carboxyl groups in a single molecule. Examples of polycarboxylic acids include saturated aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, n-dodecylsuccinic acid, nonanedicarboxylic acid, decanedicarboxylic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid (dodecanediic acid), and tetradecanedicarboxylic acid (tetradecanediic acid); alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid; aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, and terephthalic acid; polycarboxylic acids with a valency of 3 or higher, such as trimellitic acid and pyromellitic acid; and anhydrides of these carboxylic acid compounds. In addition, alkyl esters having 1 to 3 carbon atoms are also examples. Crystalline polyesters may contain one of these compounds alone or two or more compounds.

[0064] Polyhydric alcohols are compounds that contain two or more hydroxyl groups in a single molecule. Examples of polyhydric alcohols include aliphatic diols such as 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, dodecanediol, neopentyl glycol, and 1,4-butenediol; and polyhydric alcohols of three or higher valencies such as glycerin, pentaerythritol, trimethylolpropane, and sorbitol. Crystalline polyesters may contain one of these alcohols alone or two or more of them.

[0065] The method for synthesizing crystalline polyesters is not particularly limited. They can be synthesized by polycondensation (esterification) of the above-mentioned polyhydric alcohol component and polyhydric carboxylic acid component using a known esterification catalyst.

[0066] The ratio of the polyhydric alcohol component to the polyhydric carboxylic acid component is not particularly limited. For example, the equivalent ratio of the hydroxyl group of the polyhydric alcohol component to the carboxyl group of the polyhydric carboxylic acid component is preferably in the range of 1.5 / 1 to 1 / 1.5, and more preferably in the range of 1.2 / 1 to 1 / 1.2.

[0067] Catalysts that can be used in the synthesis of crystalline polyesters include alkali metal compounds such as sodium and lithium; alkaline earth metal compounds such as magnesium and calcium; metal compounds such as aluminum, zinc, manganese, antimony, titanium, tin, zirconium, and germanium; phosphite compounds; phosphate compounds; and amine compounds.

[0068] Specifically, examples of tin compounds include dibutyltin oxide, tin octoate, tin dioctoate, and their salts. Examples of titanium compounds include titanium alkoxides such as tetran-butyl titanate, tetraisopropyl titanate, tetramethyl titanate, and tetrastearyl titanate; titanium acylates such as polyhydroxytitanium stearate; and titanium chelates such as titanium tetraacetylacetonate, titanium lactate, and titanium triethanolamine.

[0069] Examples of germanium compounds include germanium dioxide. Examples of aluminum compounds include oxides such as polyaluminum hydroxide, aluminum alkoxides, and tributylaluminate. These can be used individually or in combination of two or more. The polymerization temperature and polymerization time are not particularly limited, and the reaction system may be subjected to reduced pressure during polymerization as needed.

[0070] Melting point From the viewpoint of low-temperature fixability and resistance to hot offset, the melting point (Tm) of the crystalline resin is preferably in the range of 55 to 90°C, and more preferably in the range of 60 to 85°C. The melting point of the crystalline resin can be controlled by the resin composition. Furthermore, if the crystalline resin is crystalline polyester, the melting point of the crystalline polyester is preferably 75°C or lower.

[0071] The melting point (Tm) is the temperature at the peak of the endothermic peak and can be measured by DSC (Differential Scanning Calorimetry). For example, differential scanning calorimetry (DSC measurement) is performed using a differential scanning calorimeter "DSC7000X" (manufactured by HITACHI) and a thermal analysis device controller "AS3 / DX" (manufactured by HITACHI). Specifically, 5 mg of the sample is sealed in an AL autosampler sample container φ6.8 H2.5 mm (manufactured by HITACHI) and an AL autosampler cover (manufactured by HITACHI). This is then placed in the sample holder of the "AS3 / DX," and the temperature is varied in the order of heating, cooling, and heating. During the first and second heating cycles, the temperature is raised from 0°C to 150°C at a heating rate of 10°C / min and held at 150°C for 1 minute. During the cooling cycle, the temperature is lowered from 150°C to 0°C at a cooling rate of 10°C / min and held at 0°C for 1 minute. The temperature at the top of the endothermic peak in the endothermic curve obtained during the second heating cycle is measured as the melting point.

[0072] 《Weight average molecular weight》 The weight-average molecular weight of the crystalline resin is not particularly limited. From the viewpoint of suppressing tacking and low-temperature fixation, it is preferably in the range of 1,000 to 29,000, more preferably in the range of 1,000 to 20,000, and even more preferably in the range of 1,000 to 15,000.

[0073] The weight-average molecular weight of crystalline resins can be measured by the following method. For example, an apparatus consisting of a gel permeation chromatography system "HLC-8320GPC" (manufactured by Tosoh Corporation), one "TSKgel guardcolumn SuperHZ-L" column, and three "TSKgelSuperHZM-M" columns (all manufactured by Tosoh Corporation) is used.

[0074] The column (TSK-) is stabilized at 40°C, and tetrahydrofuran (THF) is flowed through the column at this temperature at a flow rate of 0.35 mL / min as the carrier solvent. The THF sample solution of the sample (resin), adjusted to a sample concentration of 1 mg / mL, is processed using a roll mill at room temperature for 10 minutes. The solution is then processed through a membrane filter with a pore size of 0.2 μm to obtain the sample solution. 10 μL of this sample solution is injected into the apparatus along with the carrier solvent mentioned above, and detected using a refractive index detector (RI detector).

[0075] A calibration curve is created using polystyrene standard samples with a monodisperse molecular weight distribution. Based on this calibration curve, the molecular weight distribution of the sample being measured is calculated. The calibration curve is based on "polystylene standard samples TSK standard" manufactured by Tosoh Corporation: "A-500" and "F-1 The samples will be prepared from 10 samples: "F-10", "F-80", "F-380", "A-2500", "F-4", "F-40", "F-128", and "F-700". The data acquisition interval for sample analysis will be 300 ms.

[0076] Alternatively, the crystalline resin and release agent in the toner may be separated, and then the weight-average molecular weight of the crystalline resin may be calculated using the measurement method described above.

[0077] <Release agent> The release agent is not particularly limited and various known release agents can be used. The release agent is preferably a wax. Examples of wax-based release agents include hydrocarbon waxes such as polyethylene wax, paraffin wax, microcrystalline wax, and Fischer-Tropsch wax; dialkylketone waxes such as distearyl ketone; carnauba wax, montane wax, behenyl behenate, trimethylolpropane tribehenate, pentaerythritol tetramyristate, pentaerythritol tetrastearate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1,18-octadecanediol distearate, tristearyl trimellitate, and distearyl maleate; diester waxes such as stearyl sebacate, ethylene glycol palmitate, and ethylene glycol stearate; and amide waxes such as ethylenediamine dibehenylamide and tristearyl trimellitate.

[0078] Of these, hydrocarbon waxes are preferred. Examples of preferred hydrocarbon waxes include Fischer-Tropsch wax and microcrystalline wax.

[0079] The hydrocarbon wax preferably has a melting point of 50 to 95°C. If the melting point of the hydrocarbon wax is 50°C or higher, the hydrocarbon wax that seeps out from the toner particles is more likely to crystallize, which tends to improve the release effect and the scratch resistance of the formed image. If the melting point of the hydrocarbon wax is 95°C or lower, the hydrocarbon wax is more likely to seep out from the toner matrix particles during fixing, which tends to improve the release effect and the scratch resistance of the formed image. Also, if the melting point of the hydrocarbon wax is 95°C or lower, the toner matrix particles are more likely to melt during fixing, which tends to improve the low-temperature fixing properties of the toner. From the above viewpoint, it is more preferable that the melting point of the hydrocarbon wax (particularly hydrocarbon wax with 36 to 76 carbon atoms) is 80 to 90°C.

[0080] The release agent content is preferably 3 to 20% by mass, and more preferably 5 to 15% by mass, relative to the total mass of the toner matrix particles. When the release agent content is 3% by mass or more, the release properties of the toner from the fixing member are sufficiently improved. When the release agent content is 20% by mass or less, a sufficient amount of binder resin can be incorporated into the toner matrix particles, so the image fixing properties are sufficiently improved.

[0081] <Coloring agent> The coloring agent is a colored coloring agent, and is not particularly limited; examples include various known dyes and pigments. For black toner (Bk), known black colorants can be used. Specifically, black colorants such as carbon black, magnetic materials, and iron-titanium composite oxide black can be used. Examples of carbon black include channel black, furnace black, acetylene black, thermal black, and lamp black. Examples of magnetic materials include ferrite and magnetite.

[0082] For use with yellow toner (By), any known yellow colorants can be used. Specifically, as yellow colorants, dyes such as CI Solvent Yellow 19, 44, 77, 79, 81, 82, 93, 98, 103, 104, 112, and 162 can be used. As pigments, CI Pigment Yellow 14, 17, 74, 93, 94, 138, 155, 180, and 185 can be used, and mixtures of these can also be used.

[0083] For magenta toner (Bm), known magenta colorants can be used. Specifically, as magenta colorants, dyes such as CI Solvent Red 1, 49, 52, 58, 63, 111, and 122 can be used. As pigments, CI Pigment Red 5, 48:1, 53:1, 57:1, 122, 139, 144, 149, 166, 177, 178, and 222 can be used, and mixtures thereof can also be used.

[0084] a, For cyan toner (Bc), known cyan colorants can be used. Specifically, as cyan colorants, CI Solvent Blue 25, 36, 60, 70, 93, 95, etc. can be used as dyes. As pigments, CI Pigment Blue 1, 7, 15, 60, 62, 66, 76, 15:3, etc. can be used, and mixtures of these can also be used.

[0085] The content ratio of the colored colorant in the toner matrix particles is preferably in the range of 0.5 to 20 parts by mass, and more preferably in the range of 2 to 10 parts by mass, per 100 parts by mass of the binder resin.

[0086] <Charge control agent> Examples of charge control agents include various known compounds. The charge control agent content is preferably in the range of 0.1 to 5.0% by mass relative to the total mass of the binder resin.

[0087] [External Additives] The toner according to the present invention has an external additive added to the toner matrix particles. By adding the external additive, the fluidity, chargeability, cleaning properties, etc., of the toner can be further improved. In addition, by adding the external additive, the area ratio of the inorganic fine particle-derived elements can be set within the range of 4 to 10%.

[0088] As an external additive, the aforementioned inorganic fine particles can be used. In particular, silica particles or titanium dioxide particles are preferred as external additives. The inclusion of titanium dioxide particles is preferable because the uniformly added titanium dioxide particles suppress charge leakage.

[0089] The number-average primary particle size of the titanium oxide particles is preferably in the range of 60 to 120 nm. Furthermore, it is preferable that the number-average primary particle size of the titanium oxide particles is larger than that of the silica particles. The number-average primary particle size of the silica particles is preferably in the range of 10 to 120 nm.

[0090] The number-mean primary particle size is measured, for example, by the following method: Using a scanning electron microscope (SEM), such as "JEM-7401F" (manufactured by JEOL Ltd.), SEM images of inorganic microparticles magnified to an appropriate magnification are taken. The captured images are binarized using an image processing and analysis device, such as "LUZEX AP" (manufactured by Nireco Corporation), and the horizontal Ferret diameter of 100 inorganic microparticles is calculated, and the average value of these values ​​is taken as the number-mean primary particle size.

[0091] The magnification of the SEM image should be set so that the total number of inorganic microparticles in the observation area is approximately 100 to 200. This measurement method can also be applied to the number-average primary particle size of organic microparticles.

[0092] Silica particles and titanium oxide particles may be surface-modified with silane coupling agents, titanium coupling agents, higher fatty acids, silicone oils, etc., through polishing, hydrophobic treatment, etc., to improve heat resistance during storage and environmental stability. Preferred silane coupling agents include dimethyldimethoxysilane, hexamethyldisilazane (HMDS), methyltrimethoxysilane, isobutyltrimethoxysilane, and decyltrimethoxysilane. From the above perspectives, it is preferable that silica particles are surface-modified with silicone oil, and silica particles surface-modified with silicone oil will be described below.

[0093] Any silica particles prepared by any known method can be used without limitation for surface modification. Methods for producing silica particles include hydrolysis of alkoxysilane (sol-gel method) and synthesis of silica particles by vaporization of silicon chloride and gas-phase reaction in a high-temperature hydrogen flame (gas-phase method, gas combustion method). Another method for producing silica particles is to heat-treat a mixed raw material consisting of finely pulverized silica, a reducing agent such as metallic silicone powder or carbon powder, and water to form a slurry, at a high temperature under a reducing atmosphere to generate SiO gas, and then cool the SiO gas in an oxygen-containing atmosphere (melting method).

[0094] Silica particles produced by the sol-gel method are preferable because they tend to have a narrow particle size distribution and can suppress variations in the adhesion strength of external additives to white toner matrix particles.

[0095] Any known silicone oil can be used to surface-modify the silica particles. Examples of silicone oils that can be used include dimethyl silicone oil, alkyl-modified silicone oil, amino-modified silicone oil, carboxyl-modified silicone oil, epoxy-modified silicone oil, fluorine-modified silicone oil, alcohol-modified silicone oil, polyether-modified silicone oil, methylphenyl silicone oil, methylhydrogen silicone oil, mercapto-modified silicone oil, higher fatty acid-modified silicone oil, phenol-modified silicone oil, methacrylic acid-modified silicone oil, polyether-modified silicone oil, and methylstyryl-modified silicone oil.

[0096] Within a range that does not hinder the manifestation of the effects of the invention, the silicone oil used for surface modification may be used alone or in combination of two or more types. Among these, dimethyl silicone oil is preferred as the silicone oil from the viewpoint of cost and ease of handling. Furthermore, the kinematic viscosity of dimethyl silicone oil is 10 to 100 mm at 25°C. 2 It is preferable that it be / s. Alternatively, the silica particles may be hydrophobized with a silane coupling agent or the like before surface modification with silicone oil.

[0097] Furthermore, in addition to the silica particles and titanium dioxide particles, other known inorganic or organic fine particles and lubricants may be added as external additives. Other known inorganic fine particles include those made of alumina, strontium titanate, zinc titanate, calcium titanate, etc. Two or more of these may be combined. The number-average primary particle size of these other inorganic fine particles is preferably about 10 to 100 nm. The measurement of the number-average primary particle size of these other inorganic fine particles is the same as the measurement method for the number-average primary particle size of silica particles and titanium oxide particles described above.

[0098] These inorganic nanoparticles may also be hydrophobized by surface modification as needed. Surface modifiers used to modify the surface of inorganic fine particles include silane coupling agents and titanium coupling agents. Preferred silane coupling agents include dimethyldimethoxysilane, hexamethyldisilazane (HMDS), methyltrimethoxysilane, isobutyltrimethoxysilane, and decyltrimethoxysilane. Furthermore, higher fatty acids and silicone oils can be used as surface modifiers. The same silicone oils as described above can be used.

[0099] As organic microparticles, spherical organic microparticles with a number-average primary particle size of approximately 10 to 200 nm can be used. Specifically, organic microparticles made from homopolymers such as styrene and methyl methacrylate, or copolymers thereof, can be used.

[0100] Lubricants are used to further improve cleaning and transfer properties. Examples of lubricants include metal salts of higher fatty acids, such as zinc, aluminum, copper, magnesium, and calcium salts of stearate; zinc, manganese, iron, copper, and magnesium salts of oleate; zinc, copper, magnesium, and calcium salts of palmitate; zinc and calcium salts of linoleate; and zinc and calcium salts of ricinoleate. Various combinations of these external additives may be used.

[0101] The amount of inorganic fine particles added as an external additive is preferably in the range of 0.05 to 5 parts by mass, and more preferably in the range of 0.1 to 4.5% by mass, per 100 parts by mass of toner matrix particles. Furthermore, the total amount of external additives, including inorganic fine particles and organic fine particles other than inorganic fine particles, is preferably in the range of 0.05 to 5% by mass, and more preferably in the range of 0.1 to 3% by mass, relative to the total mass of the toner matrix particles.

[0102] [Toner properties] <Toner particle size> The average particle size of the toner particles is preferably in the range of 3 to 10 μm, and more preferably in the range of 4 to 8 μm, based on the volume-based median diameter (D50). The average particle size of these toner particles can be controlled during manufacturing by factors such as the concentration of the flocculant used, the amount of organic solvent added, the fusion time, and the composition of the binder resin. Because the volume-based median diameter (D50) is within the above range, extremely small dot images at the 1200 dpi level can be faithfully reproduced.

[0103] The volume-based median diameter (D50) of toner particles is measured and calculated using a measuring device that connects a "Multisizer 3" (manufactured by Beckman Coulter) to a computer system equipped with data processing software "Software V3.51".

[0104] Specifically, the toner sample to be measured is first added to a surfactant solution and mixed in, then diluted with pure water, and ultrasonic dispersion is performed to prepare a toner particle dispersion. For the purpose of dispersing the toner particles, an anionic surfactant such as sodium polyoxyethylene lauryl ether sulfate is preferably used in the surfactant solution.

[0105] Pipette the toner particle dispersion into the beaker containing "ISOTONII" (manufactured by Beckman Coulter) in the sample stand until the concentration displayed on the measuring device reaches 6-8%. Setting the concentration to this level ensures highly reproducible measurements.

[0106] Then, in the measuring device, the number of particles to be measured is set to 25,000 and the aperture diameter to 100 μm. The measurement range for toner particle size, 2 to 60 μm, is divided into 256 sections, and the frequency values ​​of the toner particle sizes are calculated. The particle size of the 50% with the largest volume integrated fraction is set as the volume-based median diameter (D50).

[0107] <Average circularity of toner particles> From the viewpoint of stability of electrostatic properties and low-temperature fixation, the average circularity of the toner particles is preferably in the range of 0.930 to 1.000, and more preferably in the range of 0.950 to 0.995.

[0108] By keeping the average circularity within the above range, both toner transfer and cleaning performance can be achieved, and the toner's charge properties remain stable, enabling the formation of high-quality images.

[0109] The average circularity of toner particles can be measured, for example, using a flow-type particle image analyzer "FPIA-3000" (manufactured by Sysmex).

[0110] Specifically, the toner sample to be measured is added to a surfactant solution, mixed, diluted with pure water, and then ultrasonically dispersed to prepare a toner particle dispersion. For the purpose of dispersing the toner particles, an anionic surfactant such as sodium polyoxyethylene lauryl ether sulfate is preferably used as the surfactant solution. Then, for example, using a flow-type particle image analyzer "FPIA-3000" (manufactured by Sysmex), imaging is performed in HPF (high magnification imaging) mode with an appropriate concentration of 3,000 to 10,000 HPF detection points.

[0111] For each individual toner particle, the circularity is calculated according to the following formula. Then, the average circularity is calculated by adding the circularity values ​​of each toner particle and dividing by the total number of toner particles. HPF If the number of detections falls within the above range, high reproducibility can be obtained. Formula: Circularity = (Perimeter of a circle with the same projection area as the particle image) / (Perimeter of the particle projection image)

[0112] <Glass transition temperature of toner> From the viewpoint of achieving both sufficient low-temperature fixation and heat-resistant storage, the glass transition temperature (Tg) of the toner is preferably in the range of 15 to 40°C, and more preferably in the range of 20 to 35°C. The glass transition temperature can be measured by the method described above.

[0113] <Core-shell structure> The toner matrix particles described above may have a multilayer structure. An example of such a multilayer structure is a core-shell structure comprising a core particle and a shell layer covering its surface.

[0114] The shell layer does not necessarily cover the entire surface of the core particles; the core particles may be partially exposed. The cross-section of the core-shell structure can be confirmed by known observation methods such as a transmission electron microscope (TEM) or a scanning probe microscope (SPM).

[0115] When the toner matrix particles have a core-shell structure, the properties such as glass transition temperature, melting point, and hardness can be made different for the core particles and the shell layer, depending on the purpose. For example, core particles with a relatively low glass transition temperature (Tg) can be created by containing a binder resin, colorant, release agent, etc. Then, a resin with a relatively high glass transition temperature (Tg) is aggregated and fused to these core particles to form a shell layer. It is preferable that the shell layer contains an amorphous resin. This configuration allows for both low-temperature fixation and heat-resistant storage. Furthermore, good charge retention performance can be obtained.

[0116] [Toner manufacturing method] Toner can be manufactured in the same way as known toners by methods such as pulverization, emulsion polymerization agglutination, suspension polymerization, and dissolution suspension. Of these, the grinding method, emulsion polymerization agglutination method, emulsion agglutination method, or suspension polymerization method is preferred, and the grinding method or emulsion polymerization agglutination method is more preferred.

[0117] In the emulsification and agglutination method, for example, an aqueous dispersion of amorphous polyester fine particles, an aqueous dispersion of amorphous vinyl resin fine particles, a release agent, and a colorant are mixed. These fine particles are then agglutinated to form moist toner matrix particles. Furthermore, in this invention, wet toner matrix particles are dried under specific conditions to produce toner matrix particles.

[0118] Here, "aqueous dispersion" refers to a solution in which a dispersion (particles) is dispersed in an aqueous medium. Furthermore, an aqueous medium refers to a solution in which the main component, that is, the component making up 50% by mass or more, is water.

[0119] Components other than water contained in aqueous media include organic solvents that dissolve in water. Examples of organic solvents that dissolve in water include: Examples include methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, and tetrahydrofuran. Among these, from the viewpoint of not dissolving the resin, alcohol-based organic solvents such as methanol, ethanol, isopropanol, and butanol are preferred.

[0120] The following is an example of a method for producing toner containing amorphous polyester and amorphous vinyl resin, but the present invention is not limited thereto. (1) A process of synthesizing amorphous polyester and preparing a dispersion of amorphous polyester fine particles. (2) A process of synthesizing amorphous vinyl resin and preparing a dispersion of amorphous vinyl resin fine particles. (3) Step of preparing a dispersion of colorant fine particles (4) A process of agglomerating amorphous polyester fine particles, amorphous vinyl resin fine particles, and colorant fine particles to form toner matrix particles. (5) A process in which thermal energy is used to mature the toner matrix particles and control their shape. (6) Step of cooling the dispersion of toner matrix particles (7) A process of filtering out toner matrix particles from an aqueous medium, washing the toner matrix particles to remove surfactants and other substances, and obtaining moist toner matrix particles. (8) Step of desolventing the wet toner matrix particles (9) A process in which the moist toner matrix particles are dried by the airflow inside the dryer. (10) Step of adding an external additive to the dried toner matrix particles.

[0121] (1) A process of synthesizing amorphous polyester and preparing a dispersion of amorphous polyester fine particles. In this process, amorphous polyester is synthesized by a conventionally known method, and a dispersion of amorphous polyester fine particles is prepared by dispersing the amorphous polyester in an aqueous medium in the form of fine particles.

[0122] Specifically, first, an amorphous polyester is dissolved or dispersed in an organic solvent to prepare an oil phase. Next, the oil phase is dispersed in an aqueous medium by phase inversion emulsification or the like to form oil droplets with a controlled particle size. After that, the organic solvent is removed to prepare an aqueous dispersion of amorphous polyester fine particles.

[0123] The amount of aqueous medium used is preferably in the range of 50 to 2000% by mass, and more preferably in the range of 100 to 1000% by mass, relative to the total mass of the oil phase liquid. From the viewpoint of the dispersion stability of oil droplets, surfactants may be added to the aqueous medium. Examples of surfactants include various conventionally known anionic surfactants, cationic surfactants, nonionic surfactants, etc.

[0124] From the viewpoint of removing oil droplets after formation, organic solvents used in the preparation of the oil phase liquid are preferably those with a low boiling point and low solubility in water. Specifically, examples include methyl acetate, ethyl acetate, methyl ethyl ketone, methyl isobutyl ketone, toluene, and xylene. These can be used individually or in combination of two or more.

[0125] The amount of organic solvent used is preferably in the range of 1 to 300% by mass relative to the total mass of the amorphous polyester. Emulsification and dispersion of the oil phase can be performed using mechanical energy.

[0126] The average particle size of amorphous polyester fine particles is 100, based on the median diameter (D50) by volume. It is preferable that the wavelength be within the range of ~400 nm. The volume-based median diameter (D50) can be measured using, for example, the "Microtrac UPA-150" (manufactured by Nikkiso Co., Ltd.).

[0127] (2) Step of preparing a dispersion of amorphous vinyl resin fine particles Amorphous vinyl resin is synthesized by the conventionally known method described above. When synthesizing the amorphous vinyl resin, it is preferable to control the molecular weight and thus the molecular weight of the toner matrix particle surface formed by adjusting the amount of chain transfer agent added as described above. A dispersion of amorphous vinyl resin fine particles is prepared by dispersing the synthesized amorphous vinyl resin in a fine particle form in an aqueous medium.

[0128] The toner matrix particles may contain internal additives such as mold release agents and charge control agents, as needed. Such internal additives may be introduced into the toner matrix particles by pre-dissolving or dispersing them in a monomer solution for synthesizing amorphous polyester or amorphous vinyl resin, for example. If a mold release agent is not pre-dissolved or dispersed in the monomer solution for synthesizing amorphous polyester or amorphous vinyl resin, a dispersion of mold release agent fine particles may be prepared separately, and this dispersion of mold release agent fine particles may be added together with other resin particle dispersions to aggregate the particles as described later.

[0129] When preparing a dispersion of mold release agent fine particles, an aqueous dispersion of mold release agent fine particles can be prepared by dispersing the mold release agent in an aqueous medium to which a surfactant is added at or above the critical micelle concentration (CMC). The release agent can be dispersed using mechanical energy. The disperser is not particularly limited and can include, for example, an ultrasonic disperser; a mechanical homogenizer; a pressurized disperser such as a Manton-Gorin or pressure homogenizer; and a medium-type disperser such as a sand grinder or diamond fine mill.

[0130] The release agent fine particles preferably have a volume-based median diameter (D50) in a dispersed state within the range of 10 to 300 nm, more preferably within the range of 100 to 200 nm, and particularly preferably within the range of 100 to 150 nm. The volume-based median diameter (D50) of the release agent fine particles can be measured, for example, using an electrophoretic light scattering photometer "ELS-800" (manufactured by Otsuka Electronics Co., Ltd.).

[0131] (3) Step of preparing a dispersion of colorant fine particles Aqueous dispersions of coloring agent fine particles can be prepared using the same procedure as for the aqueous dispersion of release agent fine particles. It is preferable to disperse the release agent fine particles by heating them above their melting point, Colorant particles do not necessarily need to be heated.

[0132] (4) A process of agglomerating amorphous polyester fine particles, amorphous vinyl resin fine particles, and colorant fine particles to form toner matrix particles. In this process, it is preferable to add a flocculant at a concentration equal to or greater than the critical flocculation concentration to an aqueous dispersion in which each fine particle is dispersed, and after the particles have flocculated to a certain extent, to add an additional dispersion of amorphous polyester fine particles. Then, shape control is performed by fusing the fine particles together to form toner matrix particles.

[0133] The flocculant is not particularly limited, but is preferably a metal salt such as an alkali metal salt or an alkaline earth metal salt. Examples of metal salts include monovalent metal salts such as sodium, potassium, and lithium; divalent metal salts such as calcium, magnesium, manganese, and copper; and trivalent metal salts such as iron and aluminum.

[0134] Specific examples of metal salts include sodium chloride, potassium chloride, lithium chloride, calcium chloride, magnesium chloride, zinc chloride, copper sulfate, magnesium sulfate, manganese sulfate, aluminum chloride, aluminum sulfate, polyaluminum chloride, and polyaluminum hydroxide. Among these, trivalent metal salts are preferred from the viewpoint that aggregation can be promoted with a smaller amount. These can be used individually or in combination of two or more.

[0135] (5) A process in which thermal energy is used to mature the toner matrix particles and control their shape. This process is performed as needed when it is necessary to mature the toner matrix particles using thermal energy and control their shape. Specifically, during the maturation process, the heating temperature, stirring speed, heating time, etc., are adjusted to heat and stir the dispersion of toner matrix particles so that the circularity of the toner matrix particles reaches the desired value.

[0136] (6) Step of cooling the dispersion of toner matrix particles In this step, the dispersion of toner matrix particles is cooled. The cooling rate is preferably in the range of 1 to 20°C / min. The specific method of cooling is not particularly limited. For example, methods include cooling by introducing a refrigerant from outside the reaction vessel, cooling by directly adding chilled water to the reaction system, and cooling by using a heat exchanger.

[0137] (7) A process of filtering out toner matrix particles from an aqueous medium, washing the toner matrix particles to remove surfactants and other substances, and obtaining moist toner matrix particles. In this process, the cooled toner matrix particles are separated into solid and liquid components from the dispersion. The resulting toner cake is then washed to remove any adhering substances such as surfactants and flocculants, obtaining wet toner matrix particles. Here, "toner cake" refers to an aggregate of wet toner matrix particles that has been flocculated into a cake-like structure.

[0138] The method of solid-liquid separation is not particularly limited and includes, for example, centrifugal separation; vacuum filtration using a Nutsche filter or the like; and filtration using a filter press or the like. In addition, during washing, it is preferable to wash with water until the electrical conductivity of the filtrate is 10 μS / cm or less.

[0139] (8) Step of desolventing the wet toner matrix particles This process is performed as needed to reduce the amount of solvent contained in the wet toner matrix particles. By performing a solvent removal treatment, the amount of solvent contained in the resulting wet toner matrix particles is reduced. It can be reduced. Furthermore, by adjusting the time, rotation conditions, pressure conditions, etc., during the solvent removal process, the amount of solvent contained in the resulting wet toner matrix particles can be adjusted.

[0140] (9) A process to dry the wet toner matrix particles. In this process, the washed, and in some cases further desolvent-treated, wet toner matrix particles are dried in a dryer. Examples of dryers include spray dryers, vacuum freeze dryers, and vacuum dryers. In particular, it is preferable to use static shelf dryers, mobile shelf dryers, fluidized bed dryers, rotary dryers, and agitated dryers as dryers. The moisture content of the dried toner matrix particles is preferably 5% by mass or less, and more preferably 2% by mass or less. Furthermore, if the dried toner matrix particles are agglomerated by weak interparticle attractive forces, the aggregates may be subjected to a crushing treatment. Mechanical crushing devices such as jet mills, Henschel mixers, coffee mills, and food processors can be used as crushing devices.

[0141] Furthermore, it is preferable to dry the toner at a temperature within the range of 10 to 45°C, and particularly preferably within the range of 20 to 40°C. If the drying temperature is higher than 45°C, the crystalline components in the toner will melt, making it difficult to control the structure.

[0142] (10) Step of adding an external additive to the dried toner matrix particles. This step involves adding the aforementioned external additive to the toner matrix particles. By adjusting the amount of external additives added to the toner matrix particles, the area ratio of elements derived from the inorganic fine particles can be set to a specific range. Furthermore, the addition of external additives improves fluidity, electrostatic properties, and cleaning properties. Examples of mixing devices for external additives include mechanical mixing devices such as Henschel mixers and coffee grinders.

[0143] The above steps (1) to (10) are just one example of a method for producing toner matrix particles, and the present invention is not limited thereto. The toner matrix particles according to the present invention may have a core-shell structure. Having a shell layer in the toner matrix particles allows for both low-temperature fixability and heat resistance. When forming the shell layer, it is preferable to form the shell layer after forming the core particles in step (4). The shell layer is preferably composed of an amorphous resin. The method for forming the shell layer is not particularly limited, and conventionally known methods can be used.

[0144] [White toner] The white toner used in the image forming method of the present invention contains at least a binder resin and a white pigment. In addition, it may optionally contain known additives other than the binder resin and white pigment.

[0145] <White pigment> The white pigment preferably contains particles of titanium dioxide, zinc oxide, barium sulfate, alumina, calcium carbonate, etc., and among these, titanium dioxide particles are preferred.

[0146] The titanium oxide particles are preferably titanium oxide particles whose surfaces are modified with a surface modifier. Titanium oxide particles whose surfaces are modified with a surface modifier are also referred to as "surface-modified titanium oxide particles" below. Here, surface modification includes both cases where a portion of the particle surface is surface-modified and cases where the entire particle surface is surface-modified.

[0147] The titanium oxide particles can be obtained by any of the following methods: the sulfuric acid method, the chlorine method, etc. Examples of crystalline structures constituting the titanium oxide particles include anatase type, rutile type, and brookite type. Among these, titanium oxide particles having a rutile type crystalline structure are particularly preferred from the viewpoint of high Mohs hardness and resistance to wear.

[0148] The materials constituting the surface modification layer in surface-modified titanium oxide particles are not particularly limited as long as they do not hinder the effects of the present invention, but examples include antimond-doped tin oxide, aluminum hydroxide, silica, siloxane, and stearic acid. Among these, antimond-doped tin oxide is preferred because it has conductivity and can prevent toner charging defects.

[0149] The particle shape of surface-modified titanium oxide particles is the same as the shape of titanium oxide particles before surface modification. The shape of surface-modified titanium oxide particles is not particularly limited and can be spherical, fusiform, needle-shaped, plate-shaped, etc., with spherical or fusiform being preferred. The average primary particle size of surface-modified titanium oxide particles is determined by measuring the Ferret diameter of 100 particles using a scanning electron microscope and averaging the results. For titanium oxide particles, a particle size of 0.15 to 0.35 μm is preferred, and 0.2 to 0.3 μm is more preferred, as this yields high whiteness and opacity. The thickness of the surface modification layer depends on the type of layer; for example, in the case of an antimond-doped tin oxide layer, it is approximately 5 to 20 nm, with 5 to 15 nm being more preferred.

[0150] Commercially available surface-modified titanium oxide particles can also be used. Examples of commercially available surface-modified titanium oxide particles include ET-500W, ET-600W, and ET-300W from Ishihara Sangyo Co., Ltd., which are surface-modified with antimond-doped tin oxide.

[0151] The content of surface-modified titanium oxide particles in the white toner matrix particles is preferably in the range of 15 to 50% by mass, and more preferably in the range of 30 to 40% by mass, relative to the total amount of white toner matrix particles, from the viewpoint of being able to exhibit sufficient whiteness (opacity) without causing a decrease in electrostatic charge. Furthermore, it is preferably in the range of 40 to 80 parts by mass, and more preferably in the range of 50 to 80 parts by mass, per 100 parts by mass of the binder resin.

[0152] <Binding resin for white toner> The binder resin used in white toner is not particularly limited, but it is preferably an amorphous resin or a crystalline resin, and more preferably an amorphous resin.

[0153] Examples of amorphous resins used in white toner include vinyl resin, urethane resin, urea resin, and amorphous polyester resin. In the present invention, vinyl resin is preferably used as the amorphous resin, and among vinyl resins, styrene-acrylic resin is preferred. Furthermore, from the viewpoint of having low viscosity and high sharp melt properties, amorphous polyester resin is also preferred. As the crystalline resin used in the white toner, conventionally known crystalline resins in this art can be used. Crystalline polyester resin is preferred as the crystalline resin. Furthermore, the amorphous resin and crystalline resin used in white toner can be the same as those used in colored toner as described above, so their explanation will be omitted. Furthermore, known additives (internal additives) other than the binder resin and white pigment can be in the same form as additives (internal additives) in colored toner matrix particles. moreover,

[0154] <External additive for white toner> Examples of external additives for white toner include inorganic fine particles, organic fine particles, and lubricants, similar to those used for colored toners. These may be used individually or in combination of two or more. Silica particles or titanium dioxide particles are more preferable as external additives for white toner.

[0155] The amount of external additives added to white toner is preferably in the range of 0.1 to 10.0 parts by mass per 100 parts by mass of white toner matrix particles.

[0156] [Method for manufacturing white toner] White toner can be manufactured by producing white toner matrix particles and then adding an external additive to the obtained white toner matrix particles. White toner matrix particles can be manufactured in the same manner as colored toner matrix particles, except that the colored colorant is replaced with a white pigment and the binder resin is appropriately modified. The volume-average particle size and average circularity of the white toner matrix particles should also preferably be within the same numerical range as those of the colored toner matrix particles.

[0157] Furthermore, the binder resin content in the white toner matrix particles is the total amount of white toner matrix particles minus the total amount of white pigment and any optional internal additives. The total content of amorphous resin in the binder resin is preferably in the range of 70 to 90% by mass, more preferably 80 to 90% by mass, relative to the total amount of binder resin. The method for adding the above-mentioned external additive to white toner matrix particles can be the same as the method for adding the external additive to colored toner matrix particles.

[0158] [Developer] Colored toners and white toners can be used in various ways, such as when they contain a magnetic material and are used as a one-component magnetic toner, when they are mixed with a carrier and used as a two-component developer, or when non-magnetic toners are used alone. All of these methods are suitable for use.

[0159] As carriers for the two-component developer, magnetic particles made of conventionally known materials such as metals like iron, ferrite, and magnetite, or alloys of these metals with metals like aluminum and lead, can be used. Ferrite particles are particularly preferred as carriers. The carrier particles are preferably in the range of 15 to 100 μm in volume average particle size, and more preferably in the range of 25 to 60 μm.

[0160] As a carrier, it is preferable to use one that is further coated with a resin, or a so-called resin-dispersed carrier in which magnetic particles are dispersed in a resin. There are no particular limitations on the resin composition for coating, but examples include olefin resins, cyclohexyl methacrylate / methyl methacrylate copolymers, styrene resins, styrene-acrylic resins, silicone resins, ester resins, or fluorine-containing polymer resins. Furthermore, the resin used to constitute the resin-dispersed carrier is not particularly limited and any known resin can be used. Examples of such resins include acrylic resins, styrene-acrylic resins, polyester resins, fluororesins, and phenolic resins.

[0161] The mixing apparatus used for mixing toner and carrier is not particularly limited and includes, for example, a Nauter mixer, a W-cone type mixer, a V-type mixer, etc. The toner content in the developer is preferably in the range of 4.0 to 8.0% by mass relative to the total mass of the developer.

[0162] [Image forming apparatus] The image forming method of the present invention is an electrophotographic image forming method. The image forming method of the present invention is preferably used in an image forming apparatus for continuous-form media (continuous-form printing machine), but may also be applied to an image forming apparatus for forming images on single-sheet paper. In particular, the image forming method of the present invention is preferably used in an image forming apparatus for continuous-form media from the viewpoint of achieving its effects.

[0163] In an electrophotographic image forming method, it is preferable to have a step of attaching the toner to a recording medium and a step of fixing the attached toner to the recording medium. Furthermore, it is preferable for the image forming method to include a step of applying varnish to the surface of the toner image formed by fixing the toner to form a varnish coat, as this improves image quality and durability.

[0164] The following describes an example of an electrophotographic image forming apparatus, but the present invention is not limited thereto. Figure 1 shows an example of the overall configuration of an image forming apparatus according to this embodiment. The image forming apparatus 100 shown in Figure 1 is a device that forms images on a continuous form medium such as roll paper or continuous forms, which is used as a recording medium. The image forming apparatus 100 is configured with a paper feeder (paper feed section) 1, a main body 2, and a winding device (winding section) 3 connected from the upstream side along the transport direction (paper transport direction) of the continuous form medium M. In Figure 1, the paper feeder 1 and winding device 3 are shown as separate components from the main body 2, but they may be integrated into a single unit.

[0165] The paper feeder 1 is a device that feeds continuous paper medium M to the main unit 2. The paper feeder 1 transports the continuous paper medium M, wound around a support shaft X, to the main unit 2 at a constant speed, driven by a motor (not shown). The operation of the motor of the paper feeder 1 is controlled by a control unit 10 located in the main unit 2. Furthermore, the paper feed device 1 is equipped with a tensioning mechanism 101 that applies tension to the continuous paper medium M. The tensioning mechanism 101 is comprised of driven rollers 101a, 101b, a dancer roller 101c, a weight 101d, and the like. The fed continuous paper medium M is wrapped around the driven rollers 101a, 101c, and 101b and fed through to the main body 2.

[0166] The main unit 2 performs image formation on the continuous form medium M fed from the paper feeder 1 using an intermediate transfer method that utilizes electrophotography. Figure 2 shows the main components of the control system of the image forming apparatus 100. As shown in Figure 2, the main body 2 includes a control unit 10, a storage unit 20, an operation display unit 30, an image forming unit 40, a paper transport unit 50, a fixing unit 60, a communication unit 70, and the like.

[0167] The control unit 10 includes a CPU (Central Processing Unit) 10a, a ROM (Read Only Memory) 10b, a RAM (Random Access Memory) 10c, etc. The CPU 10a reads a program corresponding to the processing content from the ROM 10b, loads it into the RAM 10c, and works in cooperation with the loaded program to centrally control the operation of each part of the main unit 2, as well as the paper feeder 1, the paper winding device 3, etc.

[0168] The storage unit 20 is composed of, for example, a non-volatile semiconductor memory (so-called flash memory) or a hard disk drive. The storage unit 20 stores input document data, various setting information, image data, etc. These data may also be stored in the RAM 10c of the control unit 10.

[0169] The operation display unit 30 is composed of, for example, a liquid crystal display (LCD) with a touch panel, and functions as a display unit 31 and an operation unit 32. The display unit 31 displays various operation screens, image statuses, and the operating status of each function in accordance with the display control signals input from the control unit 10. The operation unit 32 is equipped with various operation keys such as a numeric keypad and a start key, and accepts various input operations from the user and outputs operation signals to the control unit 10.

[0170] The image forming unit 40, for example, forms toner images of each color, Y (yellow), M (magenta), C (cyan), and K (black), on the photoreceptor drums 41Y, 41M, 41C, and 41K based on image data input from an external device (such as a personal computer) via the communication unit 70, and sequentially transfers them to the intermediate transfer belt 42 to superimpose the four toner images. After that, the transfer roller 43 performs a secondary transfer to the continuous form medium M fed from the paper feeder 1, thereby forming (printing) an image.

[0171] The paper transport unit 50 has a paper path 52 equipped with multiple transport rollers, etc. The paper transport unit 50 transports the continuous paper medium M, which has been transported from the paper feed device 1 to the main unit 2 based on the control of the control unit 10, to the image forming unit 40. The continuous paper medium M, on which the toner image has been formed in the image forming unit 40, is then transported to the fuser unit 60. Finally, the continuous paper medium M, on which the toner image has been fixed in the fuser unit 60, is transported to the winding device 3.

[0172] At least one pair of nip rollers 53 are provided upstream of the fixing unit 60 and downstream of the paper feed device 1 in the paper feeding path 52. Also, at least one pair of nip rollers 54 are provided downstream of the fixing unit 60 and upstream of the winding device 3. The nip rollers 53 and 54 can be pressed together and separated by a pressing drive mechanism. By pressing both the nip rollers 53 and 54 together while tension is applied to the continuous paper medium M by the tension applying mechanism 101 and the tension applying mechanism 301, it is possible to maintain the tension applied to the continuous paper medium M between the nip rollers 53 and 54 even when the rotation of the rollers is stopped and the tension application by the tension applying mechanisms 101 and 301 is released.

[0173] The fixing unit 60 fixes the toner image onto the continuous-print medium M by heating and pressurizing the medium M with a fixing nip. The fixing unit 60 includes a heating roller 61, a heating source 62 for heating the heating roller 61, an upper pressure roller 63, an endless fixing belt 64 stretched between the heating roller 61 and the upper pressure roller 63, and a lower pressure roller 65. The heating roller 61 to the fixing belt 64 are provided on the fixing surface side of the continuous form medium M, and the lower pressure roller 65 is provided opposite the fixing belt 64 across the paper feed path 52 of the continuous form medium M (i.e., on the back side of the continuous form medium M). There may also be a heating source for heating the lower pressure roller 65.

[0174] The lower pressure roller 65 is configured to be movable, and the upper pressure roller 63 and the lower pressure roller 65 can be pressed together and separated by the drive of a pressing drive mechanism (not shown). By pressing and separating the upper pressure roller 63 and the lower pressure roller 65, the fixing belt 64 and the lower pressure roller 65 can be pressed and separated. When the fixing belt 64 and the lower pressure roller 65 are pressed together, a fixing nip is formed that holds and transports the continuous paper medium M. As the continuous paper medium M passes through the fixing nip formed by the fixing belt 64 and the lower pressure roller 65, which are heated by the heating source 62, it is heated and pressurized, and the toner image is fixed.

[0175] The communication unit 70 is composed of, for example, a communication control card such as a LAN (Local Area Network) card, and is an external device connected to a communication network such as a LAN or WAN (Wide Area Network). It transmits and receives various types of data between a device (for example, a personal computer).

[0176] The winding device 3 is a device that winds up the continuous paper medium M that has been transported from the main body 2. The winding device 3 winds the continuous paper medium M that has been transported from the main body 2 onto the support shaft Y at a constant speed, driven by a motor (not shown). The winding operation of the winding device 3 is controlled by the control unit 10 provided in the main body 2. Furthermore, the winding device 3 is provided with a tensioning mechanism 301 for applying tension to the continuous sheet medium M. The tensioning mechanism 301 is composed of driven rollers 301a, 301b, a dancer roller 301c, a weight 301d, etc. The continuous sheet medium M conveyed from the main body 2 is wound around the driven rollers 301a, dancer roller 301c, and driven roller 301b, tension is applied, and it is conveyed to the support shaft Y.

[0177] In this embodiment, tensioning mechanisms are provided in both the paper feeder 1 and the winding device 3, but either one alone may be provided. The apparatus configuration and image forming method described above are exemplary embodiments for carrying out the present invention, and the present invention is not limited thereto. [Examples]

[0178] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these. In the following examples, unless otherwise specified, the operations were carried out at room temperature (25°C). Unless otherwise specified, "%" and "parts" mean "mass%" and "parts by mass," respectively.

[0179] <Preparation of binder resin fine particle dispersion (SA1)> (1) First-stage polymerization (preparation of dispersion of resin microparticles (a1)) A stirrer, temperature sensor, temperature control device, cooling pipe, and nitrogen introduction device were installed in the reaction vessel. An anionic surfactant solution, prepared by dissolving 2.0 parts by mass of the anionic surfactant "sodium lauryl sulfate" in 2900 parts by mass of deionized water, was placed in the reaction vessel. The internal temperature was then raised to 80°C while stirring at a stirring speed of 230 rpm under a nitrogen atmosphere. To this anionic surfactant solution, 9.0 parts by mass of the polymerization initiator "potassium persulfate (KPS)" was added, and after the internal temperature was raised to 78°C, a monomer solution (1-1) having the following composition was added dropwise over 3 hours. • Styrene 560 parts by mass n-butyl acrylate 162 parts by mass • 82 parts by mass of methacrylic acid n-octyl mercaptan 20 parts by mass After the dropwise addition was complete, polymerization (first-stage polymerization) was carried out by heating and stirring at 78°C for 1 hour to prepare a dispersion of resin fine particles (a1).

[0180] (2) Second polymerization: Formation of the intermediate layer (Preparation of resin microparticle (a11) dispersion) In a flask equipped with a stirring device, 51 parts by mass of behenyl behenate (ester wax, melting point: 78°C) was added as a release agent to a solution having the following composition. The solution was then heated to 85°C to dissolve the behenate and prepare monomer solution (1-2). • Styrene 100 parts by mass n-butyl acrylate 30 parts by mass • 6 parts by mass of methacrylic acid n-octyl mercaptan 2 parts by mass Meanwhile, a surfactant solution prepared by dissolving 2 parts by mass of the anionic surfactant "sodium lauryl sulfate" in 1100 parts by mass of ion-exchanged water was heated to 90°C. To this surfactant solution, 28 parts by mass of a dispersion of resin microparticles (a1) were added, calculated based on the solid content of the resin microparticles (a1). Subsequently, the monomer solutions (1-2) were mixed and dispersed for 4 hours using a mechanical disperser "Creamix" (manufactured by M-Technique Co., Ltd.) with a circulation path to prepare a dispersion containing emulsion particles with a dispersion particle size of 350 nm. To this dispersion, an initiator aqueous solution prepared by dissolving 2.5 parts by mass of the polymerization initiator "KPS" in 110 parts by mass of ion-exchanged water was added. Polymerization (second-stage polymerization) was carried out by heating and stirring this system at 90°C for 2 hours to prepare a dispersion of resin microparticles (a11).

[0181] (3) Third polymerization: Formation of the outer layer An initiator aqueous solution, prepared by dissolving 2.5 parts by mass of the polymerization initiator "KPS" in 110 parts by mass of ion-exchanged water, was added to the dispersion of the above resin fine particles (a11). Under a temperature of 80°C, monomer solutions (1-3) with the following composition were added dropwise over 1 hour. • Styrene 240 parts by mass n-butyl acrylate 82 parts by mass • 17 parts by mass of methacrylic acid n-octyl mercaptan 5.5 parts by mass After the dropwise addition was complete, polymerization (third-stage polymerization) was carried out by heating and stirring for 3 hours. Subsequently, the mixture was cooled to 28°C to prepare a dispersion of binder resin microparticles (SA1) in which binder resin microparticles (A1) were dispersed in an anionic surfactant solution.

[0182] <Preparation of binder resin fine particle dispersions (SA2) to (SA7)> In the method for preparing the binder resin microparticle dispersion (SA1), binder resin microparticle dispersions (SA2) to (SA7) were prepared in the same manner as the preparation of binder resin microparticle dispersion (SA1), except that the amount of n-octyl mercaptan used and the type of release agent were changed as shown in Table I. The amount of each release agent added was the same as in (SA1).

[0183] [Table 1]

[0184] <Preparation of amorphous polyester resin fine particle dispersion (PB1)> (1) Synthesis of amorphous polyester resin (styrene-acrylic modified polyester resin (B1)) The compounds listed below were placed in a 10-liter four-necked flask equipped with a nitrogen inlet tube, dehydration tube, stirrer, and thermocouple, and subjected to a condensation polymerization reaction at 230°C for 8 hours. The reaction was then carried out at 8 kPa for 1 hour, followed by cooling to 160°C. • Bisphenol A propylene oxide 2-mol adduct 500 parts by mass Terephthalic acid 117 parts by mass ·Fumaric acid 82 parts by mass • Esterification catalyst (tin octylate) 2 parts by mass Next, a mixture having the composition shown below was added dropwise over 1 hour using a dropping funnel. After addition, the addition polymerization reaction was continued for 1 hour while maintaining the temperature at 160°C, then the temperature was raised to 200°C and maintained at 10 kPa for 1 hour. Subsequently, acrylic acid, styrene, and butyl acrylate were removed to obtain styrene-acrylic modified polyester resin (B1). • Acrylic acid 10 parts by mass • Styrene 30 parts by mass • Butyl acrylate 7 parts by mass • Polymerization initiator (di-t-butyl peroxide) 10 parts by mass The glass transition temperature of this styrene-acrylic modified polyester resin (B1) was 60°C, and the softening temperature was 105°C.

[0185] (2) Preparation of amorphous polyester resin fine particle dispersion (AB1) 100 parts by mass of the obtained styrene-acrylic modified polyester resin (B1) was pulverized using a "Randellmill Model: RM" (manufactured by Tokuju Kogyo Co., Ltd.). This was mixed with 638 parts by mass of a pre-prepared 0.26% by mass sodium lauryl sulfate solution. The mixture was ultrasonically dispersed for 30 minutes at V-LEVEL, 300 μA using an ultrasonic homogenizer "US-150T" (manufactured by Nippon Seiki Seisakusho Co., Ltd.) while stirring. This resulted in a median diameter (D) based on volume. 50 A dispersion of amorphous polyester resin fine particles (AB1) was prepared, in which amorphous polyester resin fine particles (B1) with a 250 nm wavelength were dispersed.

[0186] <Preparation of colorant particle dispersion (P1)> While stirring the solution prepared by adding 90 parts by mass of sodium dodecyl sulfate to 1600 parts by mass of deionized water, 420 parts by mass of copper phthalocyanine (CI pigment blue 15:3) was gradually added. Next, the obtained dispersion was subjected to dispersion treatment using a stirring device "Creamix" (manufactured by M-Technique Co., Ltd.) to prepare a colorant particle dispersion (P1). The colorant particles in the dispersion had a median diameter of 120 nm by volume.

[0187] <Preparation of White Coloring Agent Particle Dispersion (P2)> A 0.1 mol / L hydrogen chloride aqueous solution was added to 1000 parts by mass of deionized water to adjust the pH to 4.5. Then, 300 parts by mass of ET-500W titanium dioxide particles (manufactured by Ishihara Sangyo Co., Ltd.) and 3 parts by mass of an anionic surfactant (Neogen RK, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) were added as white coloring particles. Next, the mixture was dispersed in a round stainless steel flask using a homogenizer (Ultra-Turrax T50: manufactured by IKA) for 5 minutes to obtain a dispersion of white coloring agent particles (P2). ET-500W is a surface-modified titanium oxide particle in which spherical titanium oxide particles (number-mean primary particle size: 200 nm, Mohs hardness: 7.5) with a rutile-type crystal structure are surface-modified with antimond-doped tin oxide. The thickness of the surface modification layer is negligibly thin compared to the particle size of the titanium oxide particles.

[0188] <Cyan Toner Preparation> (Preparation of cyan toner (1)) In a reaction vessel equipped with a stirrer, temperature sensor, and cooling tube, 288 parts by mass of binder resin fine particle dispersion (SA1) and 2000 parts by mass of ion-exchanged water were added. A 5 mol / liter sodium hydroxide aqueous solution was then added to adjust the pH to 10. Subsequently, 40 parts by mass of the coloring agent particle dispersion (P1) was added on a solid content basis. Next, an aqueous solution prepared by dissolving 60 parts by mass of magnesium chloride in 60 parts by mass of ion-exchanged water was added over 10 minutes at 30°C under stirring. After standing for 3 minutes, the heating was started, and the system was heated to 80°C over 60 minutes. Once it reached 80°C, 40 parts by mass (in terms of solid content) of amorphous polyester resin fine particle dispersion (AB1) (first addition) were added over 10 minutes. The particle growth reaction was then continued while maintaining the temperature at 80°C. In this state, the particle size of the core particles was measured using a "Coulter Multisizer 3" (manufactured by Coulter-Beckman). Volume-based median diameter (D 50 When the particle size reached 6.0 μm, 32 parts by mass of amorphous polyester resin fine particle dispersion (AB1) (second time) was added over 30 minutes, on a solid content basis. When the supernatant of the reaction solution became clear, an aqueous solution of 190 parts by mass of sodium chloride dissolved in 760 parts by mass of ion-exchanged water was added to stop particle growth. Furthermore, the temperature was increased, and the mixture was heated and stirred at 90°C to promote particle fusion. Using the toner average circularity measuring device "FPIA-2100" (manufactured by Sysmex) (with 4000 HPF detections), the average circularity reached 0.945, at which point it was cooled to 30°C to obtain a dispersion of cyan toner matrix particles (1). The dispersion of cyan toner matrix particles (1) was separated into solid and liquid components using a centrifuge to form a wet cake of cyan toner matrix particles. This was washed with deionized water at 35°C using a centrifuge until the electrical conductivity of the filtrate was 5 μS / cm. Then, it was transferred to a "Flash Jet Dryer" (manufactured by Seishin Corporation) and dried until the moisture content was 0.5% by mass. To dried cyan toner matrix particles (1), 1% by mass of hydrophobic silica particles (number mean primary particle size = 12 nm) and 0.3% by mass of hydrophobic aluminum oxide particles (number mean primary particle size = 18 nm) were added. Cyan toner (1) was prepared by mixing using a Henschel mixer. The hydrophobic silica particles are silica particles that have been hydrophobized with hexamethyldisilazane. The hydrophobic aluminum oxide particles are aluminum oxide particles that have been hydrophobized with alkylsilane (4 carbon atoms).

[0189] (Preparation of cyan toner (2) to (15)) Cyanonners (2) to (15) were prepared in the same manner as cyanonner (1), except that the amounts of binder resin fine particle dispersion and amorphous polyester resin fine particle dispersion used, and the types and amounts of external additives were as shown in Table II. The hydrophobic silica listed in the table is the same as the hydrophobic silica particles used in the preparation of cyan toner (1). Furthermore, the hydrophobic titanium oxide listed in the table refers to hydrophobic titanium oxide particles with a number mean primary particle size of 20 nm. These hydrophobic titanium oxide particles are titanium oxide particles that have been hydrophobized with isobutyltrimethoxysilane.

[0190] [Table 2]

[0191] <Preparation of white toner (W1)> A stirrer, condenser, and thermometer were attached to the reaction vessel. 200 parts by mass (solid content) of the binder resin particle dispersion (SA1) obtained above, 30 parts by mass (solid content) of amorphous polyester resin particle dispersion (AB1), 175 parts by mass (solid content) of white coloring agent particle dispersion (PB2), 0.5 parts by mass of aqueous solution of polyoxyethylene lauryl ether sodium sulfate, and 100 parts by mass of deionized water were added to the reaction vessel. While stirring, 0.1N hydrochloric acid was added to adjust the pH to 2.5. Next, 0.4 parts by mass of an aqueous solution of aluminum chloride (10% aqueous solution in terms of AlCl3) was added dropwise over 10 minutes. Then, the temperature was increased at a rate of 0.05°C / min while stirring, and the particle size of the agglomerated particles was measured as appropriate using a "Multisizer 3" (Beckman Coulter). When the volume-average particle size (volume-based median diameter) of the agglomerated particles reached 5.0 μm, the temperature was stopped, and the pH was adjusted to 7 using a 0.05 (mol / liter) aqueous solution of sodium hydroxide while stirring. After that, the internal temperature was further increased to 85°C, and when the average circularity reached 0.960 using an FPIA-2100 (Sysmex), it was cooled to room temperature at a rate of 10°C / min. After repeated filtration and washing of this reaction solution, white toner matrix particles were obtained by drying. To 100 parts by mass of the prepared white toner matrix particles, 0.5% by mass of silica particles and 0.5% by mass of titanium dioxide particles were added and placed in a Henschel mixer model "FM20C / I" (manufactured by Nippon Coke Industries Co., Ltd.). The mixer was then stirred for 20 minutes at a rotation speed of 60 m / s, producing "white toner (W1)" consisting of white toner particles. Furthermore, the product temperature during external mixing was set to 40°C ± 1°C. If it reached 41°C, cooling water was flowed into the outer bath of the Henschel mixer at a flow rate of 5 L / min. If it reached 39°C, the temperature inside the Henschel mixer was controlled by flowing cooling water at a rate of 1 L / min. The silica particles and titanium oxide particles added to the white toner matrix particles are the same as the hydrophobic silica particles and hydrophobic titanium oxide particles used in the production of the cyan toner, respectively.

[0192] <Preparation of white toner (W2) and (W3)> White toners (W2) and (W3) were prepared in the same manner as white toner (W1), except that the binder resin fine particle dispersion (SA1) used was as shown in Table III.

[0193] [Table 3]

[0194] <Preparation of Developer> (1) Carrier creation 100 parts by mass of ferrite core and 5 parts by mass of copolymer resin particles of cyclohexyl methacrylate / methyl methacrylate (copolymerization ratio 5 / 5) were placed in a high-speed mixer equipped with stirring blades. The mixture was stirred and mixed at 120°C for 30 minutes, and a resin coating layer was formed on the surface of the ferrite core by the action of mechanical impact force, thereby obtaining a carrier with a volume-based median diameter of 50 μm. The median diameter based on the volume of the carrier was measured using a laser diffraction particle size distribution analyzer "HELOS" (manufactured by Sympathic Co., Ltd.) equipped with a wet disperser.

[0195] (2) Mixing of toner and carrier The above carrier was added to each of the toners (cyan toners 1-15 and white toners W1-W3) to achieve a toner concentration of 6%. The mixture was then mixed for 30 minutes at a rotation speed of 45 rpm using a micro-type V-type mixer (Tsutsui Rikagakuki Co., Ltd.) to produce cyan developers (1)-(15) and white developers (W1)-(W3).

[0196] [evaluation] <Separability> As an image forming apparatus for continuous-feed media, the "AccurioLabel 400" (manufactured by Konica Minolta) was used, and the above-mentioned two-component developer was installed in this apparatus. Image formation was performed using N-Mirror 73 / P22 / L8W (manufactured by Oji Tack Co., Ltd.) as the printing medium under normal temperature and humidity conditions (temperature 22°C, humidity 50%RH), and the amount of toner deposited on the image before fixing was adjusted to be as shown in Table IV. Subsequently, the surface temperature of the fixing and heating element was set to 200°C, and the image was output. As shown in Table IV, for Examples 1-4 and Comparative Examples 1 and 2, images were formed using a cyan developer, while for Examples 5-13, images were formed using a white developer first, followed by image formation with a cyan developer. Then, the streaks on the image surface caused by the fixing separation failure in the direction perpendicular to the paper passing direction were visually evaluated. According to the following criteria, R2 to R4 were regarded as qualified. (Criteria) R4: No streaks R3: Slight streaks can be seen from a specific angle R2: Streaks can be seen from a specific angle R1: Clear streaks can be seen from any angle

[0197] <Low-temperature fixing property> As an image forming apparatus for continuous accounting media, "AccurioLabel 400" (manufactured by Konica Minolta) was used, and the above two-component developer was mounted on this apparatus as the developer. In an environment of normal temperature and humidity (temperature 22°C, humidity 50%RH), image formation was performed using N mirror 73 / P22 / L8W (manufactured by Oji Tack) as the printing medium, and the toner adhesion amount in the image before fixing was adjusted to the values in Table IV. After that, the surface temperature of the fixing heating member was changed in 5°C increments from 120°C to 200°C, and the image was fixed at each temperature. As shown in Table IV, for Examples 1 to 4, Comparative Examples 1 and 2, image formation was performed with a cyan developer, and for Examples 5 to 10, after image formation with a white developer, image formation was performed with a cyan developer. The obtained images were visually evaluated, and the temperature at which offset no longer occurred was defined as the minimum fixing temperature. According to the following criteria, R3 to R5 were regarded as qualified. (Criteria) R5: The minimum fixing temperature is less than 150°C. R4: The minimum fixing temperature is 150°C or more and less than 160°C. R3: The minimum fixing temperature is 160°C or more and less than 170°C. R2: The minimum fixing temperature is 170°C or more and less than 180°C. R1: The minimum fixing temperature is 180°C or more.

[0198] <Varnish coating property> As an image forming apparatus for continuous-feed media, the "AccurioLabel 400" (manufactured by Konica Minolta) was used, and the above-mentioned two-component developer was installed in this apparatus. Image formation was performed using N-Mirror 73 / P22 / L8W (manufactured by Oji Tack) as the printing medium under normal temperature and humidity conditions (temperature 22°C, humidity 50%RH). The amount of toner attached to the image before fixing was adjusted to the values ​​shown in Table IV, the surface temperature of the fixing heating element was set to 200°C, and the image was output. As shown in Table IV, for Examples 1 to 4 and Comparative Examples 1 and 2, image formation was performed using cyan developer, while for Examples 5 to 10, image formation was performed using white developer first, followed by image formation with cyan developer. UV VECTA Coat Varnish PC-3KW2 (manufactured by T&K) was applied to the created fixed image using a bar coater to a thickness of 5 μm. Subsequently, using a high-pressure mercury lamp, the integrated light intensity of the image surface was measured to be 120-130 mJ / cm². 2 The varnish was cured by irradiating it with ultraviolet light to form a varnish layer. UV VECTA Coat Varnish PC-3KW2 contains a polymerizable monomer for varnish and a photopolymerization initiator (radical polymerization initiator). The polymerizable monomer for varnish has a polymerizable functional group containing an ethylenic double bond. The surface of the varnish layer in the obtained images was visually inspected, and the applicability was evaluated based on the presence or absence of pinholes or repellency according to the following criteria. R2 to R4 were considered acceptable according to the following criteria. (standard) R4: There are no pinholes in the 10cm x 10cm area. R3: There are one to two tiny pinholes within a 10cm x 10cm area. R2: There are 3 to 10 tiny pinholes within a 10cm x 10cm area. R1: There are 11 or more pinholes or missed spots within a 10cm x 10cm area.

[0199] <Area ratio of elements derived from inorganic microparticles> For the images output in the aforementioned evaluation method for <varnishability>, the area ratio of elements derived from inorganic nanoparticles was calculated relative to the area of ​​all elements measured by X-ray photoelectron spectroscopy (ESCA). The results are shown in Table IV below. A K-Alpha X-ray photoelectron spectroscopy analyzer (manufactured by Thermo Fisher Scientific) was used, and measurements were taken under the following conditions. The peak areas of carbon (peak area C), oxygen (peak area O), and elements derived from inorganic fine particles, all located within 3 nm of the outermost surface of toner particles, were identified. The peak areas of elements derived from the inorganic fine particles include the peak area of ​​silicon and the peak area of ​​titanium. Each peak area was identified using a relative sensitivity factor from the respective atomic peak area. Then, from the obtained peak areas, the area ratio of elements derived from inorganic nanoparticles to the total area of ​​all elements was calculated based on equation A below. Formula A: (Total peak areas of elements derived from inorganic microparticles) / (Peak area C + Peak area O + Total peak areas of elements derived from inorganic microparticles) × 100 (Measurement conditions) X-ray: Al monochromatic source Acceleration: 12kV, 6mA Resolution: 50eV Beam system: 400 μm Pass energy: 50 eV Step size: 0.1eV

[0200] [Table 4]

[0201] In Table IV, "Amorphous Polyester Content [mass%]" refers to the content of amorphous polyester relative to the toner matrix particles in cyan toner.

[0202] As shown in the above results, by using the image forming method of the present invention, even when image formation is performed using an image forming apparatus for continuous accounting media, the separability from the fixing device can be ensured as compared with the comparative example. Further, it is recognized that since an image forming apparatus for continuous accounting media excellent in varnish coating property and low-temperature fixing property and capable of high-speed printing is used, it is possible to cope with high-speedization.

Explanation of Signs

[0203] 100 Image forming apparatus 1 Paper feeding device 101 Tension applying mechanism 101a, 101b Driven rollers 101c Dancer roller 101d Weight 2 Main body part 10 Control part 20 Storage part 30 Operation display part 31 Display part 32 Operation part 40 Image forming part 50 Paper conveyance part 60 Fixing part 61 Heating roller 62 Heat source 63 Upper pressure roller 64 Fixing belt 65 Lower pressure roller 70 Communication part 3 Take-up device 301 Tension applying mechanism 301a, 301b Driven rollers 301c Dancer roller 301d Weight

Claims

1. An image forming method for forming a toner image on a continuous-print medium using toner, The area ratio of elements derived from inorganic fine particles to the total area of ​​all elements measured by X-ray photoelectron spectroscopy (ESCA) of the toner image is within the range of 4 to 10%. The toner has toner matrix particles, The toner matrix particles contain a release agent and amorphous polyester. A method for forming an image characterized by the following features.

2. The element derived from the inorganic fine particles is Si or Ti. The image forming method according to feature 1.

3. The mold release agent is a hydrocarbon wax. The image forming method according to feature 1.

4. The content of the amorphous polyester is in the range of 10 to 50% by mass relative to the content of the toner matrix particles. The toner image containing white pigment is printed on top of the white toner image, The difference in softening point between the white toner containing the white pigment and the toner is 14°C or less. The image forming method according to any one of claims 1 to 3.

Images