Toner, toner set, image forming method, image forming apparatus, and process cartridge

Abstract

A toner is provided that includes a polyester, a polyurethane elastomer, a wax, and one of a white pigment and a black pigment. The toner has a transmittance of less than 5% for all visible light wavelengths when formed into a solid image with a deposition thickness of 30 µm on an OHP substrate.

Description

[DESCRIPTION][Title of Invention]TONER, TONER SET, IMAGE FORMING METHOD, IMAGE FORMING APPARATUS, AND PROCESS CARTRIDGE [Technical Field]

[0001] The present disclosure relates to a toner, a toner set, an image forming method, an image forming apparatus, and a process cartridge.[Background Art]

[0002] An electrophotographic method forms a visible image by developing an electrostatic latent image with a developer. In this method, an electrostatic latent image is formed on an electrostatic latent image bearer (also referred to as “photoconductor”) including a photoconductive substance. The electrostatic latent image is developed with a developer including a toner to form a toner image, and the toner image is transferred onto a transfer material such as a paper sheet and then fixed thereon by heat and pressure to form a fixed image.To form a full-color image by the electrophotographic method, it is common to use a toner set that combines a black toner with cyan, magenta, and yellow toners, which are toners of three process colors (sometimes simply referred to as process colors).

[0003] In recent years, as an electrophotographic color image forming apparatus has become common, the use of its printed matter has expanded to a great variety. Particularly, in the field of general consumer goods of custom-made design or the like, there is a growing need for electrophotographic printing on a material that cannot be printed (fixed) with a conventional electrophotographic toner intended for printing on a paper medium. Specifically, there is an increasing demand for printing on a fabric medium such as a sport team uniform, shoe, or bag, or a leather medium.

[0004] As a method for printing a desired image or a design such as a logo on a fabric product such as a T-shirt, a sweatshirt, or a work cloth, a wood material, a metal plate, or the like, a method or an apparatus has been proposed that uses an inkjet printer for printing a design directly onto a printing object (Patent literatures 1 and 2).Further, an apparatus that uses a thermal transfer printer to perform printing directly onto a fabric such as clothing has been proposed (Patent literature 3).Further, a method or an apparatus has been proposed in which an image is printed on a transfer paper sheet and then thermally transferred to a print medium using an iron or the like (Patent literatures 4 and 5).Further, there are proposed a peelable sheet having a releasable surface, a print image, formed on the peelable sheet, which can be thermally transferred to a transfer medium, a pulverized toner for thermal transfer print sheet which enables printing on a dark color transfer material by printing an image with a special white toner on the print image, and a thermal transfer print sheet (Patent literature 6).[Citation List][Patent Literature]

[0005] [PTL 1]Japanese Unexamined Patent Application Publication No. 07-336466 [PTL 2]Japanese Unexamined Patent Application Publication No. 08-207263 [PTL 3]Japanese Unexamined Patent Application Publication No. 11-157139 [PTL 4]Japanese Unexamined Patent Application Publication No. 05-077557 [PTL 5]Japanese Unexamined Patent Application Publication No. 09-087980 [PTL 6]Japanese Unexamined Patent Application Publication No. 2014-59486 [Summary of Invention] [Technical Problem]

[0006] A direct printing method using an inkjet printer or a thermal transfer printer as described in Patent literatures 1 to 3 is considered effective for producing a large number of printing matters of the same shape or producing a large printing matter. However, for producing printing objects which are small in size (such as clothing) and come in different shapes in many varieties and in small quantities, a method of transporting the printing objects to the printer is different for each printing object, making the production time-consuming. Further, for printing on a dark color printing material, a large amount of white ink needs to be used, which significantly reduces maintainability due to the settling of the white pigment, clogging of the head, or the like. Further, when making a thick white concealing layer, the printing speed becomes slower compared to printing on a white or light color printing material.

[0007] A method of printing an image on a transfer paper sheet and then thermally transferring the image to the printing object, as described in Patent literature 4, does not have the problems of the above-mentioned methods in that the method is not limited by the shape of the printing object. However, the size of the transfer paper sheet is standard (e.g., mainly A4 or A3), thusthe shape of the transfer paper sheet needs to be prepared separately for transferring the image to the printing object.

[0008] Patent literature 5 describes a method of thermally transferring an image onto a printing object using two transfer paper sheets and may be able to solve the problems of Patent literature 4. However, this method is troublesome in that it requires preforming the thermal transfer process twice using two transfer paper sheets. Further, in reality, the temperature, pressing pressure, and the like during transfer differ for each production sample, requiring the work skill.

[0009] A printing method of Patent literature 6 is considered to solve the above-mentioned problems. However, the productivity of the white toner is low, making it difficult to obtain enough concealment for a dark color transfer object (transfer medium). Since the concealment by the white toner is insufficient, the transfer object bleeds through the white color, causing a reduction in saturation and brightness of the color image. Further, when the white concealing layer is thickened by repeated printing to obtain sufficient concealment, the productivity decreases with multiple printings, and the transfer object is more likely to curl with each printing. This causes transport problems and misalignment within the apparatus, making reproducible printing difficult.

[0010] Further, in a conventional image forming method using transfer, the toner has a high transmittance, and there is a need to improve the accuracy and quality of image formation. Further, differences in image quality occur depending on the components and deposition amount of the toner, making it difficult to form consistent images. Further, in addition to the requirement of good fixation to the transfer object such as a cloth, when the transfer object is a T-shirt or the like, good washing fastness is also required.

[0011] Thus, an object of the present invention is to provide a toner which has excellent fixation to a transfer object, provides good washing fastness to the transfer object on which an image has been formed, and can exhibit good color image reproducibility even if the transfer object has a dark color.[Solution to Problem]

[0012] In order to solve the above-mentioned problems, a toner is provided that includes a polyester, a polyurethane elastomer, a wax, and one of a white pigment and a black pigment. The toner has a transmittance of less than 5% for all visible light wavelengths when formed into a solid image with a deposition thickness of 30 pm on an OHP substrate.[Advantageous Effects of Invention]

[0013] According to embodiments of the present invention, a toner is provided which has excellent fixation to a transfer object, provides good washing fastness to the transfer object on which an image has been formed, and can exhibit good color image reproducibility even if the transfer object has a dark color.[Brief Description of Drawings]

[0014] A more complete appreciation of embodiments of the present disclosure and many of the attendant advantages and features thereof can be readily obtained and understood from the following detailed description with reference to the accompanying drawings.[FIG. 1]FIG. l is a schematic diagram illustrating an image forming apparatus. [FIG. 2]FIG. 2 is a schematic diagram illustrating an image forming apparatus. [FIG. 3]FIG. 3 is a schematic diagram illustrating an image forming apparatus.[FIG. 4]FIG. 4 is a schematic diagram illustrating an image forming apparatus.[FIG. 5]FIG. 5 is a schematic diagram illustrating a process cartridge.[FIG. 6]FIG. 6 is a diagram illustrating an image for evaluation.The accompanying drawings are intended to depict embodiments of the present disclosure and should not be interpreted to limit the scope thereof. The accompanying drawings are not to be considered as drawn to scale unless explicitly noted. Also, identical or similar reference numerals designate identical or similar components throughout the several views. [Description of Embodiments]

[0015] In describing embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of this specification is not intended to be limited to the specific terminology so selected and it is to be understood that each specific element includes all technical equivalents that have a similar function, operate in a similar manner, and achieve a similar result.Referring now to the drawings, embodiments of the present disclosure are described below. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.Hereinafter, a toner, a toner set, an image forming method, an image forming apparatus, and a process cartridge according to embodiments of the present invention are described with reference to the drawings. Note that the present invention is not limited to the following embodiments, but may be modified within scopes suggested by those skilled in art, such asother embodiments, addition, modification, and deletion. Any aspect that achieves the functions and effects of the present invention is within the scope of the present invention.

[0016] (Toner and toner set)A toner according to an embodiment of the present invention is used in an electrophotographic image forming apparatus and is used for forming a thermal transfer print sheet. The thermal transfer print sheet is a transfer sheet on which an image is formed using the toner and is used for transferring the image to a transfer object by thermal transfer. The toner has a transmittance of less than 5% for all visible light wavelengths when formed into a solid image having a deposition thickness of 30 pm on an OHP substrate, and includes a polyester, a polyurethane elastomer, wax, and a white pigment or a black pigment.

[0017] A toner set according to an embodiment of the present invention is used in an electrophotographic image forming apparatus and includes a plurality of toners used for forming a thermal transfer print sheet. The thermal transfer print sheet is a transfer sheet on which an image is formed using the toner and is used for transferring the image to a transfer object by thermal transfer. The toners included in the toner set each has a transmittance of less than 5% for all visible light wavelengths when formed into a solid image having a deposition thickness of 30 pm on the transfer sheet, and the toner set include at least the following toner(A), toner (B), and toner (C).(A) A toner including a white pigment, a polyester, a polyurethane elastomer, and wax.(B) A toner including a black pigment, a polyester, a polyurethane elastomer, and wax.(C) A toner including at least one of a white pigment and a black pigment, a colorant other than the white pigment and the black pigment, a polyester, a polyurethane elastomer, and wax.

[0018] According to embodiments of the present invention, the fixation to the transfer object is excellent, the washing fastness of the transfer object on which the image has been formed is good, and the reproducibility of the color image can be good even if the transfer object has a dark color. Further, according to embodiments of the present invention, the cost of producing the thermal transfer print sheet can be reduced.

[0019] The toner according to an embodiment of the present invention is used in an electrophotographic image forming apparatus and is used for forming a thermal transfer print sheet, and may be referred to as a thermal transfer print sheet toner. Further, the toner set according to an embodiment of the present invention is used in an electrophotographic image forming apparatus and is used for forming a thermal transfer print sheet, and may be referred to as a thermal transfer print sheet toner set.

[0020] The toner according to an embodiment of the present invention has a transmittance of less than 5%, preferably less than 1%, for all visible light wavelengths when formed into a solid image having a deposition thickness of 30 pm on an OHP substrate. The deposition amount can be increased to increase the thickness by repeatedly printing and layering images. In the present specification, a transmittance for all visible light wavelengths when a solid image having a deposition thickness of 30 pm is formed on an OHP substrate may be referred to as “above-mentioned transmittance”.

[0021] The transmittance in the present disclosure refers to the maximum transmittance within the visible light wavelength range (i.e., 380 to 780 nm). The measurement is performed with a 30 pm thick solid image formed on an OHP substrate using a spectrophotometer. For example, the measurement is performed using an ultraviolet / visible / near infrared spectrophotometer (UV-3600 manufactured by Shimadzu Corp.) with a film holder under the following conditions.•Wavelength range: 380 nm to 780 nmScan speed: Medium• Sampling pitch: 0.5 nmSlit width: 5.0 nmNote that, for measuring the above-mentioned transmittance, the toner deposition thickness is confirmed to be 30 pm by three-dimensional measurement using a confocal microscope OPTELICS Hl 200 (manufactured by Lasertec Corp.).

[0022] In order to make the above-mentioned transmittance less than 5%, the toner needs to include a white pigment that totally reflects or scatters visible light, or a black pigment that totally absorbs wavelengths in the visible light range. The above-mentioned transmittance can also be adjusted by the type and content of the white pigment or the black pigment.The above-mentioned transmittance is defined as a physical property that allows the color of the toner to be expressed without being affected by the color of the transfer object when an image to be transferred is transferred and formed on a dark color transfer object, and is a parameter used to distinguish the toner according to an embodiment of the present invention from an ordinary color toner. Even if the thickness of the ordinary color toner is increased, the transmittance does not become less than 5% in some wavelength ranges. By using the toner with the above-mentioned transmittance of less than 5%, a color image that is not affected by the transfer object can be formed.

[0023] <White pigment>A toner according to one embodiment of the present invention includes a white pigment, a polyester, a polyurethane elastomer, and wax. Such a toner may be referred to as a toner (A).The toner (A) corresponds to the above-mentioned toner (A) included in the toner set according to an embodiment of the present invention.

[0024] The white pigment used in the present disclosure is not particularly limited and can be appropriately selected according to the purpose. For example, titanium dioxide, white lead, talc, kaolin, zinc sulfide, barium sulfate, calcium carbonate, zinc oxide, hollow silica, and the like can be used. Further, the surface of the white pigment can be treated with silicon, zirconia, aluminum, an organic substance such as a polyol, or the like, and used. It is preferable to use titanium dioxide which is surface-treated with aluminum or an organic substance such as a polyol. It is presumed that the surface treatment allows the release agent in the toner to be wetted by the white pigment, thereby reducing the hardness of the toner layer, resulting in a white concealing layer that is less susceptible to cracking.

[0025] The optimum content of the white pigment in the toner varies depending on the type of pigment. However, for example, the content in the toner is preferably 20% by mass or more and 50% by mass or less, more preferably 30% by mass or more and 40% by mass or less. When the content of the white pigment is the above-mentioned lower limit value or more, the concealing property can be prevented from decreasing, and the design of the transferred object can be prevented from penetrating through and decreasing the saturation and brightness of the image. Further, when the content of the white pigment is the above-mentioned upper limit value or less, flexibility can be ensured, and the toner layer can be prevented from cracking even if the transferred object is flexible.

[0026] <Black pigment>A toner according to one embodiment of the present invention includes a black pigment, a polyester, a polyurethane elastomer, and wax. Such a toner may be referred to as a toner (B). The toner (B) corresponds to the above-mentioned toner (B) included in the toner set according to an embodiment of the present invention.

[0027] The black pigment used in the present disclosure is not particularly limited and can be appropriately selected depending on the purpose. However, preferable examples thereof include, but are not limited to, carbon black alone, and a mixture of carbon black as the main component and copper phthalocyanine or the like for adjusting the hue and brightness.

[0028] The content of the black pigment in the toner can be appropriately selected. However, for example, when carbon black is used, the content in the toner is preferably 6% by mass or more and 10% by mass or less.When the content of the black pigment is the above-mentioned lower limit value or more, the concealing property can be prevented from decreasing, and the design of the transfer objectcan be prevented from penetrating through. When the content of the black pigment is the above-mentioned upper limit value or less, the volume resistivity of the toner can be prevented from decreasing, and the charging characteristics can be stabilized.

[0029] <Colorant>A toner according to one embodiment of the present invention includes at least one of a white pigment and a black pigment, a polyester, a polyurethane elastomer, and wax, and further includes a colorant other than the white pigment and the black pigment. Such a toner may be referred to as a toner (C). The toner (C) corresponds to the above-mentioned toner (C) included in the toner set according to an embodiment of the present invention. Hereinafter, unless otherwise specified, when the term “colorant” is used, it refers to a colorant excluding the above-mentioned white pigment and the above-mentioned black pigment. The colorant included in the toner is not particularly limited, and a colorant that is normally used can be appropriately selected and used. A range of colors that can be expressed is expanded by including the colorant.

[0030] The toner (C) included in the toner set according to an embodiment of the present invention includes at least one of a white pigment and a black pigment, a colorant other than the white pigment and the black pigment, a polyester, a polyurethane elastomer, and wax. The toner (C) only needs to include either the white pigment or the black pigment, and preferably includes both the white pigment and the black pigment. When the toner(C) includes both the white pigment and the black pigment, a range of colors that can be expressed is expanded.

[0031] The colorant preferably has small absorption for the wavelengths of 800 nm or more. Examples of such a colorant include, but are not limited to, Naphthol Yellow S, Hansa Yellow (10G, 5G, G), Cadmium Yellow, Yellow Iron Oxide, Loess, Chrome Yellow, Titanium Yellow, Polyazo Yellow, Oil Yellow, Hansa Yellow (GR, A, RN, R), Pigment Yellow L, Benzidine Yellow (G, GR), Permanent Yellow (NCG), Balkan Fast Yellow (5G, R), Tartrazine Lake, Quinoline Yellow Lake, Anthrazan Yellow BGL, Isoindolinone Yellow, Red Iron Oxide, Red Lead, Orange Lead, Cadmium Red, Cadmium Mercury Red, Antimony Orange, Permanent Red 4R, Para Red, Fire Red, p-Chloro-o-nitroaniline Red, Lithol Fast Scarlet G, Brilliant Fast Scarlet, Brilliant Carmine BS, Permanent Red (F2R, F4R, FRL, FRLL, F4RH), Fast Scarlet VD, Vulcan Fast Rubine B, Brilliant Scarlet G, Lithol Rubine GX, Permanent Red F5R, Brilliant Carmine 6B, Pigment Scarlet 3B, Bordeaux 5B, Toluidine Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, BON Maroon Light, BON Maroon Medium, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarine Lake, Thioindigo Red B, Thioindigo Maroon, Oil Red, Quinacridone Red, Pyrazolone Red, Polyazo Red, Chrome Vermilion, Benzidine Orange, Perynone Orange, Oil Orange, Cobalt Blue, Cerulean Blue, Alkali Blue Lake, Peacock Blue Lake, Victoria Blue Lake, metal-freePhthalocyanine Blue, Phthalocyanine Blue, Fast Sky Blue, Indanthrene Blue (RS, BC), Indigo, Dioxane Violet, Anthraquinone Violet, Chrome Green, Zinc Green, Viridian, Emerald Green, Pigment Green B, Naphthol Green B, Green Gold, Acid Green Lake, Malachite Green Lake, Phthalocyanine Green, Anthraquinone Green, Titanium Oxide, Zinc Oxide, Lithopone, Perylene Black, Perinone Black, and a mixture thereof. These pigments may be used alone or in combination of two or more types.

[0032] The content of the colorant in the toner is preferably, for example, 1% by mass or more and 12% by mass or less. In this case, a color can be expressed by taking advantage of the absorption wavelength specific to the colorant.

[0033] When the toner according to an embodiment of the present invention includes the white pigment and the colorant, it has low transparency (the above-mentioned transmittance is less than 5%), making it difficult to achieve full color expression using a subtractive color method as is the case with a general electrophotographic color toner. Thus, it is preferable to express a specific color by mixing the colorants in advance and including them in the toner according to the purpose, design, or the like. Although the toner according to an embodiment of the present invention does not exclude the method of expressing a color by overlapping toner layers, it is preferable to mix the colorants in advance and include them in the toner to form each toner layer as a single layer. That is, it is preferable that the toner image on the thermal transfer print sheet is a single-layer toner image that does not overlap with any other toner image. By forming the toner layer as a single layer, it is expected to simplify the process and reduce the costs.

[0034] <Polyester>The polyester (which may also be referred to as a polyester resin) used in the toner is preferably obtained by condensation polymerization of an alcohol and a carboxylic acid. The alcohol used is not particularly limited and can be appropriately selected depending on the purpose. However, examples of the alcohol include, but are not limited to, a glycol such as ethylene glycol, diene glycol, triethylene glycol, or propylene glycol, an etherified bisphenol such as l,4-bis(hydroxymethyl)cyclohexane or bisphenol A, a dihydric alcohol monomer, and a trihydric or higher polyhydric alcohol monomer.

[0035] Further, the carboxylic acid is not particularly limited and can be selected appropriately depending on the purpose. However, examples of the carboxylic acid include a divalent organic acid monomer such as maleic acid, fumaric acid, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, or malonic acid, and a trivalent or higher polyvalent carboxylic acid monomer such as 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, l,3-dicarboxyl-2-methylenecarboxypropane, or 1,2, 7, 8- octanetetracarboxylic acid.

[0036] The content of the polyester in the toner is preferably 20% by mass or more and 60% by mass or less. When the content is 20% by mass or more, the pulverization property can be prevented from decreasing, the charging characteristics can be prevented from decreasing, and the stability of the toner can be improved. When the content is 60% by mass or less, flexibility on the transfer object can be ensured and the occurrence of cracking in the toner layer formed on the flexible transfer object can be prevented.

[0037] The softening temperature and glass transition temperature of the polyester are both preferably 55°C or higher. When they are 55°C or higher, the heat-resistant preservability of the toner image can be ensured.

[0038] <Polyurethane elastomer>The polyurethane elastomer used in the toner generally has excellent tensile force (tensile strength), abrasion resistance, elasticity, and oil resistance, making it a suitable binder resin for the present disclosure.

[0039] In terms of a composition of the polyurethane, it is preferable to use a polyurethane elastomer including 1,4-butanediol (1,6-hexanediol), adipic acid, diphenylmethane diisocyanate, and the like.Further, a specific product name of the polyurethane elastomer to be used is not particularly limited and can be selected appropriately depending on the purpose. However, examples thereof include, but are not limited to, a hot melt powder ECOFREEN POWDER (manufactured by Ecofreen Co., Ltd.), T8175N, T5102S (manufactured by DIC Covestro Polymer Ltd.), E780M128, P22MBRNAT, E360MSXW (manufactured by Nippon Miractran Co, Ltd.), and 57 IF (manufactured by BASF).

[0040] The softening temperature and glass transition temperature of the polyurethane elastomer are both preferably 45 °C or lower, and more preferably 20°C or lower.The glass transition temperature of the polyurethane elastomer is more preferably -60°C or higher and 0°C or lower, even more preferably -50°C or higher and -10°C or lower.When the softening temperature and glass transition temperature of the polyurethane elastomer are within these ranges, the flexibility of the toner layer after fixation can be ensured.

[0041] The softening point of the polyurethane elastomer is preferably 90°C or higher and 130°C or lower, more preferably 100°C or higher and 120°C or lower. When the softening point of thepolyurethane elastomer is within this range, offset during fixation and thermal transfer can be prevented, and durability can be maintained. The softening temperature is different form the softening point, and the measurement methods for these are described below.

[0042] When the polyester and the polyurethane elastomer are used in combination, a sea-island structure can be formed in a non-compatible manner. The polyurethane elastomer is used in combination with the polyester. The toner according to an embodiment of the present invention includes the polyurethane elastomer and the polyester. It is preferable that, in the sea-island structure in the cross section of the toner, a domain includes the polyurethane elastomer, a matrix includes the polyester resin, and the domain and the matrix in the cross section of the toner are non-compatible.

[0043] The weight average molecular weight of the polyurethane elastomer is preferably 20,000 to 100,000, more preferably 20,000 to 80,000, even more preferably 20,000 to 60,000. When the weight average molecular weight is 20,000 or more, there is no risk of the fixed image melting when ironed, and when the weight average molecular weight is 100,000 or less, it is easy to melt and knead an adhesive with other toner components when making the toner.

[0044] The content of the polyurethane elastomer is not particularly limited and can be appropriately selected according to the purpose. The content in the toner is preferably 40% by mass or more and 70% by mass or less, more preferably 50% by mass or more and 60% by mass or less. When the content is 40% by mass or more, the toner can be sufficiently fixed to a flexible medium such as a fabric, and the toner layer can be flexible after fixation. When the content is 70% by mass or less, the heat-resistant preservability of the toner is not deteriorated, and there is no risk of aggregation of toner particles. Further, if the thermal transfer print sheet toner does not include the polyurethane elastomer, cracking occurs, and the image cannot be maintained.

[0045] Further, the polyurethane elastomer can be entirely or partially substituted with any of polyethylene terephthalate, polyethylene isophthalate, polybutylene terephthalate, polybutylene isophthalate, and styrene butadiene rubber, which have the same properties as the polyurethane elastomer.

[0046] <Wax (release agent)>The wax (release agent) is not particularly limited and can be appropriately selected depending on the purpose. One type may be used alone, or two or more types may be used in combination.

[0047] The release agent that can be used in the present disclosure is not particularly limited and can be appropriately selected depending on the purpose. However, examples thereof include, but are not limited to: an aliphatic hydrocarbon such as liquid paraffin, microcrystalline wax, natural paraffin, synthetic paraffin, polyolefin wax, or a partial oxide, fluoride, or chloride thereof; animal oil such as beef tallow or fish oil; vegetable oil such as coconut oil, soybean oil, rapeseed oil, rice bran wax, or carnauba wax; a higher aliphatic alcohol or higher fatty acid such as montan wax; a fatty acid amide; a fatty acid bisamide; a metal soap such as zinc stearate, calcium stearate, magnesium stearate, aluminum stearate, zinc oleate, zinc palmitate, magnesium palmitate, zinc myristate, zinc laurate, or zinc behenate; a fatty acid ester; and poly vinylidene fluoride. Of these, it is preferable to include at least ester wax such as a fatty acid ester.

[0048] The toner according to an embodiment of the present invention preferably includes a wax dispersant. The dispersant is preferably a copolymer composition including at least styrene, butyl acrylate, and acrylonitrile as monomers, and a polyethylene adduct of the copolymer composition. The content of the wax dispersant is preferably 7 parts by mass or less relative to 100 parts by mass of the toner.

[0049] The wax content in the toner is not particularly limited and can be selected appropriately depending on the purpose. However, the content is preferably 0.1% by mass or more and 8.0% by mass or less, more preferably 1.0% by mass or more and 6.0% by mass or less. When the content is 0.1% by mass or more, the toner and the fixing roller (or fixing belt) separate during fixation, preventing a wastepaper jam. Further, when the content is 8.0% by mass or less, the toner can be sufficiently fixed to a plastic film.

[0050] <Charge control agent>The toner may include a charge control agent.The charge control agent can be selected appropriately according to the purpose as long as it is white or colorless. Examples of the charge control agent include: an onium salt such as a phosphonium salt and a lake pigment thereof; a triphenylmethane dye and a lake pigment thereof; a metal salt of higher fatty acid; a di organotin oxide such as dibutyltin oxide, dioctyltin oxide, or dicyclohexyltin oxide; a diorganotin borate such as dibutyltin borate, dioctyltin borate, or dicyclohexyltin borate, an organic metal complex; a chelate compound; a monoazo metal complex; an acetylacetone metal complex, an aromatic hydroxycarboxylic acid; a metal complex of aromatic dicarboxylic acid; and a quaternary ammonium salt. Other examples include: an aromatic hydroxycarboxylic acid; an aromatic mono- and polycarboxylic acid, and a metal salt thereof; an anhydride; an ester; and a phenol derivative such as bisphenol. These may be used alone or in combination of two or more types.

[0051] When the charge control agent is added internally to the toner, the content is not particularly limited and can be set appropriately depending on the purpose. However, the charge control agent is preferably added in an amount of 0.1% to 10% by mass relative to the total amount of the binder resin.

[0052] <Extemal additive>The toner according to an embodiment of the present invention can use inorganic fine particles or the like as an external additive.The inorganic fine particles for external addition used in the present disclosure are not particularly limited and can be appropriately selected depending on the purpose. However, examples thereof include, but are not limited to, silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, silica sand, clay, mica, wollastonite, diatomaceous earth, chromium oxide, cerium oxide, red iron oxide, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, and silicon nitride. Of these, silica, alumina, and titanium oxide are preferable.

[0053] Further, the inorganic fine particles that have been surface-treated with a hydrophobic treatment agent may be used. The hydrophobic treatment agent is not particularly limited and can be appropriately selected depending on the purpose. However, examples of the preferable surface treatment agent include, but are not limited to, a silane coupling agent, a silylating agent, a silane coupling agent having a fluorinated alkyl group, an organic titanate coupling agent, and an aluminum coupling agent. Further, sufficient effects can be obtained by using silicone oil as the hydrophobic treatment agent.

[0054] Further, the average diameter of primary particles of the inorganic fine particles is not particularly limited and can be appropriately selected depending on the purpose. However, the average diameter is preferably 5 to 500 nm, more preferably 5 to 200 nm. When the average diameter is 5 nm or more, the aggregation of the inorganic fine particles can be prevented, and the inorganic fine particles can be uniformly dispersed in the toner. When the average diameter is 500 nm or less, the heat-resistant preservability can be improved due to the filler effect. The average particle diameter described herein is a value obtained by directly determining the particle diameter from a photograph obtained by a transmission electron microscope, and it is preferable to observe at least 100 or more particles and use the average value of the major axis.

[0055] <Flow improving agent>The toner may include a flow improving agent as an additive. The flow improving agent is not particularly limited and can be appropriately selected according to the purpose, as long asit is capable of increasing hydrophobicity by surface treatment and preventing deterioration of flow characteristics and charging characteristics under a high humidity environment. Examples of the flow improving agent include, but are not limited to, a silane coupling agent, a silylating agent, a silane coupling agent having a fluorinated alkyl group, an organic titanate coupling agent, an aluminum coupling agent, silicone oil, and modified silicone oil. It is preferable that the silica and titanium oxide as the external additives are surface-treated with such a flow improving agent and used as hydrophobic silica and hydrophobic titanium oxide, respectively.

[0056] <Cleaning improving agent>The toner may include a cleaning improving agent as an additive. The cleaning improving agent is not particularly limited and can be appropriately selected according to the purpose, as long as it can be added to the toner according to one embodiment of the present invention for removing the developer remaining on the photoconductor and the primary transfer medium after transfer. Examples of the cleaning improving agent include, but are not limited to, a fatty acid metal salt of stearic acid or the like such as zinc stearate or calcium stearate, and polymer fine particles produced by soap-free emulsion polymerization such as polymethyl methacrylate fine particles or polystyrene fine particles. The polymer fine particles preferably have a relatively narrow particle size distribution, and preferably have a volume average particle size of 0.01 pm or more and 1 pm or less.

[0057] <Measurement>«Method for measuring particle size and particle size distribution based on volume% of toner»As a method for measuring the particle size distribution and particle size based on the volume% of the toner, for example, measurement can be performed using a particle size measuring device (“MULTISIZER 3” manufactured by Beckman Coulter, Inc.) with an aperture diameter of 100 pm, and analysis can be performed using analysis software (Beckman Coulter MULTISIZER 3 Version 3.51). An example of the measurement is presented below.

[0058] 0.5 ml of a 10% by mass surfactant (alkylbenzene sulfonate, NEOGEN SC-A manufactured by DKS Co. Ltd.) is added to a 100 ml glass beaker, and then 0.5 g of each toner is added to the glass beaker. The mixture is stirred with a micro spatula, and then 80 ml of ion-exchanged water is added to the mixture to obtain a dispersion liquid. The resulting dispersion liquid is subjected to a dispersion treatment for 10 minutes using an ultrasonic disperser (W-l 13MK-II manufactured by Honda Electronics Co., Ltd.) to obtain a sample dispersion liquid of the toner. The toner sample dispersion liquid is subjected to the measurement using MULTISIZER 3 described above and ISOTON III (manufactured by Beckman Coulter, Inc.)as a measurement solution. From the viewpoint of measurement reproducibility and avoiding errors in the particle size, the toner sample dispersion liquid is added dropwise so that the concentration indicated by the device is 8 ± 2%, thereby measuring the volume average particle size of the toner.

[0059] «Particle size distribution and volume average particle size of toner»The particle size distribution based on volume% of the toner is not particularly limited and can be appropriately selected according to the purpose. The volume average particle size of the toner is not particularly limited and can be appropriately selected according to the purpose. However, the volume average particle size is preferably 10 to 25 pm, more preferably 12 to 20 pm.

[0060] With the above-mentioned toner, the developing ability can be increased by increasing the toner particle size, the developing amount of toner in one development can be increased, and the pile height of the toner layer can be increased, making it easier to fill in the unevenness of the surface of a flexible medium such as a fabric. Further, in consideration of the trade-off with transferability, it is more preferable for the toner to have a particle size distribution with a peak in a range of 10 to 25 pm in the particle size distribution based on volume%. For the same reason, it is more preferable for the toner to have a volume average particle size of 12 to 20 pm. Further, it is preferable that the toner particles having a particle size of 5 pm or less account for 10% or less by number.

[0061] «Confirmation of presence of resin in toner and quantification»The presence of the resin included in the toner according to an embodiment of the present invention can be confirmed and quantified suitably by gas chromatography mass spectrometry (GC-MS) or NMR (Nuclear Magnetic Resonance). Specifically, this can be performed by the following procedures, devices, and conditions.

[0062] «Component analysis by GC-MS»-Sample preparation-The toner is dispersed in chloroform and stirred overnight to obtain a dispersion liquid. This dispersion liquid is then centrifuged to collect only the supernatant. The collected supernatant is evaporated and dried, and the composition is analyzed using a gas chromatograph mass spectrometer (GC-MS). An example of the measurement conditions for GC-MS is presented below. Note that the sample is prepared as a mixture in which about 1 pL of a methylating agent (20% methanol solution of tetramethylammonium hydroxide: TMAH) was added dr op wise to about 1 mg of the sample.

[0063] -Measurement conditions-•Pyrolysis-gas chromatography mass spectrometer (Py-GCMS) analyzer: QP2010 (manufactured by Shimadzu Corp.)•Heating furnace: Py2020D (manufactured by Frontier Laboratories Ltd.)•Heating temperature: 320°C•Column: Ultra ALLOY-5 (L=30 m, I.D.=0.25 mm, Film=0.25 pm, manufactured by GL Sciences Inc.)•Column temperature: 50°C (holding time: 1 min)-heating (10°C / min)-340°C (holding time: 7 min)Split ratio: 1 : 100•Column flow rate: 1.0 ml / minIonization method: El method (70 eV)•Measurement mode: Scan modeSearch data: NIST 20 MASS SPECTRAL LIB.

[0064] <Component analysis by NMR»-Sample preparation-The toner is dispersed in chloroform and stirred overnight to obtain a dispersion liquid. This dispersion liquid is then centrifuged to collect only the supernatant. The collected supernatant is evaporated and dried, and used as a sample for 'H-NMR and °C-NMR to analyze the composition by NMR. A method for preparing the sample for 'H-NMR, a method for preparing the sample for °C-NMR, and an example of the measurement conditions are presented below.

[0065] (1) Method for preparing sample for 'H-NMR1 mL of d8-toluene (manufactured by FUJIFILM Wako Pure Chemical Corp.) is added to 100 mg of a sample, and the sample is heated and dissolved using a hair dryer, thereby preparing a sample for 'H-NMR.(2) Method for preparing sample for °C-NMR1 mL of deuterated 1,2-dichlorotoluene (manufactured by FUJIFILM Wako Pure Chemical Corp.) is added to 100 mg of a sample, and the sample is heated and dissolved using a hair dryer, thereby preparing a sample for °C-NMR.

[0066] -Measurement conditions-NMR device: ECX-500 (manufactured by JEOL Ltd.)•Measuring nucleus: 'H (500 MHz), measurement pulse file: single pulse dec. jxp (XH), 45°C pulse, 20,000 times of accumulation, relaxation delay: 4 seconds, data point: 32K, offset: 100 ppm, observation width: 250 ppm, measurement temperature: 70°C•Measuring nucleus =13C (125 MHz), measurement pulse: single pulse dec. jxp (13C), 45°C pulse, 64 times of accumulation, relaxation delay: 5 seconds, data point: 32K, observation width: 15 ppm, measurement temperature: 65°C

[0067] «Measurement of weight average molecular weight»The weight average molecular weight of the resin used in the toner can be obtained by measuring the molecular weight distribution of a tetrahydrofuran (THF) soluble fraction using a gel permeation chromatography (GPC) measuring device. The GPC measuring device is not particularly limited and can be appropriately selected according to the purpose. For example, the device under the product name GPC-150C (manufactured by Waters Corp.) or the like can be used.

[0068] The column used for measuring the weight-average molecular weight is not particularly limited and can be appropriately selected depending on the purpose. Examples of the column include, but are not limited to, by product name, KF801 (organic solvent SEC (GPC) column), KF 802 (organic solvent SEC (GPC) column), KF803 (organic solvent SEC (GPC) column), KF804 (organic solvent SEC (GPC) column), KF805 (organic solvent SEC (GPC) column), KF806 (organic solvent SEC (GPC) column), and KF807 (organic solvent SEC (GPC) column) (all manufactured by Showa Denko K.K.).

[0069] A method for measuring the weight-average molecular weight of the resin used in the toner is not particularly limited and can be appropriately selected depending on the purpose. For example, the measurement can be performed by the following method.A column is stabilized in a heat chamber at 40°C, and a solvent, THF, is passed through the column at a flow rate of 1 mL per minute. Next, 0.05 g of the sample is sufficiently dissolved in 5 g of THF, and then filtered with a pretreatment filter (e.g., product name: CHROMATODISC, pore size: 0.45 pm, manufactured by Kurabo Industries Ltd.). The final sample concentration is adjusted to 0.05% by mass to 0.6% by mass. Then, 50 pL to 200 pL of the THF sample solution in which the sample concentration is adjusted is injected into the column to separate the THF-soluble fraction included in the THF sample solution. Next, the conversion to the molecular weight is performed by using a detector (e.g., a refractive index (RI) detector (device name: GPC-150C manufactured by Waters Corp.)), thereby measuring the weight-average molecular weight (Mw) of the THF-soluble fraction included in the THF sample solution.

[0070] In the measurement of the weight-average molecular weight Mw and the number-average molecular weight Mn of the THF-soluble fraction included in the sample, the molecular weight distribution of the sample is calculated from the relationship between logarithmicvalues and count numbers of the calibration curve, which is created using several monodisperse polystyrene standard samples.As the standard polystyrene samples for creating the calibration curve, for example, those with molecular weights of 6* 102, 2.1 >< 102, 4* 102, 1.75>< 104, 5.1 x l04, l. l x lO5, 3.9x l05, 8.6x l05, 2x l06, and 4.48x l06, manufactured by Pressure Chemical Co. or Tosoh Corp., are used. It is preferable to use at least 10 standard polystyrene samples. Further, it is preferable to use the refractive index (RI) detector as a detector.

[0071] «Method for measuring softening temperature»The softening temperature can be measured using a flow tester (CFT-500D manufactured by Shimadzu Corp.). Specifically, while 1.0 g of a sample is heated by the flow tester at a temperature rise rate of 6°C / min, the sample is extruded from a nozzle with a diameter of 1.0 mm and a length of 1.0 mm by applying a load of 1.96 MPa by a plunger. The plunger descending amount of the flow tester is plotted over the temperature to obtain an S-shaped curve indicating temperature (°C) / stroke (mm). The temperature at which deformation of the sample first occurs (the temperature at which deformation of the sample first occurs as the sample changes from a solid state to a rubber-like state) can be determined as the softening temperature.

[0072] «Method for measuring softening point»The softening point can be measured using a flow tester (CFT-500D manufactured by Shimadzu Corp.). Specifically, while 1.0 g of a sample is heated by the flow tester at a temperature rise rate of 6°C / min, the sample is extruded from a nozzle with a diameter of 1.0 mm and a length of 1.0 mm by applying a load of 1.96 MPa by a plunger. The plunger descending amount of the flow tester is plotted over the temperature to obtain an S-shaped curve indicating temperature (°C) / stroke (mm). Tm is read from the obtained S-curve. Specifically, the maximum value of the stroke in the S-shaped curve is defined as SI, and the stroke value of the baseline on the low temperature side is defined as S2. The temperature at which the stroke value in the S-shaped curve is (Sl+S2) / 2 is defined as the softening point Tm of the measurement sample.

[0073] «Method for measuring glass transition temperature»The glass transition temperature (Tg) can be measured, for example, using a differential scanning calorimeter (DSC210 manufactured by Seiko Instruments Inc.). Specifically, 0.01 to 0.02 g of a sample is weighed into an aluminum pan at room temperature and cooled to -20°C at a temperature drop rate of 10°C / min using the differential scanning calorimeter. The sample is then heated to 200°C at a temperature rise rate of 10°C / min, and the temperature at an intersection point of an extension line of the baseline and a tangent line indicating the maximum slope from a rising part of the peak to the top of the peak can be determined as Tg.

[0074] <Method for producing toner>A method for producing the toner according to an embodiment of the present invention is not particularly limited and can be appropriately selected depending on the purpose. An example of the method for producing the toner according to an embodiment of the present invention is described below.

[0075] A melting kneading pulverization method is preferable as the method for producing the toner according to an embodiment of the present invention. This is because the white pigment has a larger specific gravity than other toner constituent materials, making it difficult to perform granulation using a chemical method such as a dissolution suspension method, and because a step of cooling and rolling a molten kneaded product of the toner components is required to form domains. By contrast, a chemical method such as a dissolution suspension method can be used in the present disclosure provided that the method allows internal dispersion of the white pigment and adopts a toner material constitution and a process that can form domains.

[0076] The shape and size of the domains are determined by the compatibility of the domain material and the matrix material (determined by the molecular weight and composition of each material) and the stretching force applied when the molten kneaded product is cooled and rolled.Thus, in the easiest method for controlling the domain diameter and shape, it is preferable that the materials incompatible to each other are used, and the thickness of the molten kneaded product of the toner materials are reduced to an appropriate thickness by determining in advance the relationship between the domain size and shape, and the rolling thickness. The thickness is preferably adjusted to 1 mm or less. By reducing the thickness in this manner, domains with a suitable size can be obtained.

[0077] A method for producing the toner according to an embodiment of the present invention includes, for example, a mixing step, a melting and kneading step, a solidification step, a fine pulverization step, and a classification step. The mixing step is a step of obtaining a mixture of the binder resin. The melting and kneading step is a step of obtaining a kneaded product of the mixture. The solidification step is a step of obtaining a solid product of the kneaded product. The fine pulverization step is a step of obtaining a pulverized product of the solid product. The classification step is a step of classifying and recovering the pulverized product.

[0078] -Step of obtaining mixture of binder resin (mixing step)-First, the binder resin, the colorant, and the release agent, optionally the charge control agent or the like are mixed in a mixer to obtain a mixture (mixing step).The mixer is not particularly limited and can be appropriately selected depending on the purpose. Examples of the mixer include, but are not limited to, a Henschel mixer (product name: FM20B manufactured by Nippon Coke & Engineering. Co., Ltd.) and SUPERMIXER (SMV-20Ba manufactured by Kawata Mfg. Co., Ltd.).

[0079] -Step of obtaining kneaded product of mixture (melting and kneading step)-Next, the obtained mixture is melted and kneaded using a thermal melt kneader to obtain a kneaded product (melting and kneading step).The thermal melt kneader is not particularly limited and can be appropriately selected depending on the purpose. Examples of the thermal melt kneader include, but are not limited to, by product name, twin-screw extruder PCM series (manufactured by IKEGAI CO., LTD.), a TEM type extruder (manufactured by Shibaura Machine Co., Ltd.), a twin-screw extruder PCM Co-Kneader (manufactured by Buss AG), and an open roll type continuous kneader KNEADEX (manufactured by Nippon Coke & Engineering. Co., Ltd.).

[0080] -Step of obtaining solid product of kneaded product (solidification step)-Next, the obtained kneaded product is cooled and solidified to obtain a solid product (solidification step). A cooling method and a solidification method are not particularly limited and can be appropriately selected according to the purpose. For example, any appropriate methods can be used.However, for performing efficient fine pulverization in the next fine pulverization step, it is preferable to reduce the solid product to a certain coarse particle size in the solidification step.

[0081] Examples of the preferable method include pelletizing the kneaded product in the solidification step after the kneading step.Examples of the pelletizing step include, but are not limited to, a strand cutting method, a water-cooled hot cutting method, and an underwater cutting method. For example, in the strand cutting method, the kneaded molten product immediately after the kneading step is extruded through a die with a diameter of about 3 mm to form a strand. The resulting strand is cooled in a cooling device such as a water tank, and after cooling, the strand is cut using a pelletizer and processed into pellets.

[0082] It is possible to process the strand into the pellets of the appropriate particle size by adjusting the feed amount of melting and kneading and the feed amount of pelletizer, thereby adjusting the strand thickness and cut width.

[0083] The pellet particle size is preferably 0.5 mm or more and 3 mm or less in diameter, more preferably 1 mm or more and 2 mm or less in diameter. By coarsening the particles before the fine pulverization step, the smaller particles improve the efficiency of the fine pulverization.However, the smaller the strand diameter, the more likely the strand is to break during the step, making it difficult to maintain the step stability. Thus, processing with a diameter of 1 mm or more is preferable.

[0084] -Step of obtaining pulverized product of solid product (fine pulverization step)-Next, the obtained solid product is finely pulverized to obtain a pulverized product (fine pulverization step).The solid product can be pulverized using a known pulverization method. Examples of a known pulverization method that can be used include, but are not limited to, a jet mill method in which the toner is included in a high-speed air stream, and the solid product is pulverized using the energy generated when the toner is collided with a collision plate, an inter-particle collision method in which toner particles are collided with each other in an air stream, and a mechanical pulverization method in which the toner is supplied into a narrow gap with a rotor rotating at high speed to pulverize the toner.

[0085] It is preferable to use a low-temperature pulverization method to pulverize the toner according to an embodiment of the present invention.Some substances have the property of becoming suddenly brittle at a certain temperature or lower, which is referred to as “low-temperature brittleness”. By utilizing this property, it is possible to pulverize rubber, a plastic, and the like, which are difficult to pulverize at room temperature. The low-temperature pulverization, which uses the extremely low temperature of liquid nitrogen at -196°C, is also referred to as freeze pulverization.

[0086] By using the freeze pulverization method, the pulverization is significantly improved, and the shape of the pulverized particles is stabilized, making it possible to obtain finely pulverized material more suitable for the toner. In this freeze pulverization, it is preferable to use the mechanical pulverization method described above, in which the toner is supplied into a narrow gap with a rotor rotating at high speed and pulverized. Specifically, the coarsely pulverized kneaded product is put into a cooler, processed in a pulverizer while being cooled with liquid nitrogen, and sieved to obtain particles with a desired particle size or smaller. The coarse particles remaining on the sieve are returned to the cooler and pulverized again.

[0087] As a cooling means, a cooling machine such as a chiller can be used. The product temperature of the coarse particles to be finely pulverized is 5°C minus of the glass transition point Tg of the coarse particles, or lower, more preferably 20°C minus of the glass transition point Tg of the coarse particles, or lower.

[0088] -Step of classifying and recovering pulverized product (classification step)-Next, the pulverized product is classified to recover the pulverized product having a predetermined volume average particle size. This can provide the toner (classification step). A classification method is not particularly limited, and an airflow type, a rotating rotor type, or the like can be appropriately selected depending on the purpose.Examples of the airflow type classifier include, but are not limited to, an Elbow-Jet Air Classifier (manufactured by Matsubo Corp.), and examples of the rotating rotor type classifier include, but are not limited to, a TSP separator and a TTSP separator (manufactured by Hosokawa Micron Group).

[0089] Further, the toner according to one embodiment of the present invention can be produced using a dissolution suspension method. When the toner is produced using the dissolution suspension method, the toner materials such as the binder resin, the colorant, the release agent, and, if necessary, the charge control agent are dissolved or dispersed in an organic solvent to prepare an oil phase, which is then dispersed into an aqueous medium (aqueous phase) to induce reaction of the binder resin. This produces a dispersion liquid including a dispersion (oil droplets) which includes a prepolymer in which the toner materials are emulsified or dispersed. Subsequently, the organic solvent is removed from the dispersion liquid, and filtration, washing, and drying are performed, and further classification and the like are performed as necessary to produce toner base particles. The base particles thus obtained with the dissolution suspension method are subjected to granulation, thereby providing the toner according to one embodiment of the present invention.

[0090] The organic solvent is not particularly limited and can be appropriately selected depending on the purpose. However, an organic solvent with a boiling point of lower than 150°C is preferable because the organic solvent is easily removed.The organic solvent with a boiling point of lower than 150°C is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include, but are not limited to, toluene, xylene, benzene, carbon tetrachloride, methylene chloride, 1,2- di chloroethane, 1, 1,2-tri chloroethane, trichloroethylene, chloroform, monochlorobenzene, dichloroethylidene, methyl acetate, ethyl acetate, methyl ethyl ketone, and methyl isobutyl ketone. These may be used alone or in combination of two or more types. Of these, ethyl acetate, toluene, xylene, benzene, methylene chloride, 1,2-di chloroethane, chloroform, and carbon tetrachloride are preferable, and ethyl acetate is more preferable.

[0091] The aqueous medium is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include, but are not limited to, water, a solvent miscible with water, and a mixture thereof. These may be used alone or in combination of two or more types. Of these, water is preferable.

[0092] The solvent miscible with water is not particularly limited and can be appropriately selected according to the purpose. Examples thereof include, but are not limited to, an alcohol, a lower ketone, dimethylformamide, tetrahydrofuran, and a cellosolve.

[0093] The alcohol is not particularly limited and can be selected appropriately depending on the purpose. Examples thereof include, but are not limited to, methanol, isopropanol, and ethylene glycol.The lower ketone is not particularly limited and can be selected appropriately depending on the purpose. Examples thereof include, but are not limited to, acetone and methyl ethyl ketone.

[0094] A method for removing the organic solvent from the dispersion liquid is not particularly limited and can be appropriately selected according to the purpose. Examples thereof include, but are not limited to, a method in which the temperature of the entire reaction system is gradually increased to evaporate the organic solvent in the oil droplets, and a method in which the dispersion liquid is sprayed into a dry atmosphere to remove the organic solvent in the oil droplets.

[0095] The classification in the dissolution suspension method may be performed by removing the fine particle portion in the liquid using a cyclone, decanter, centrifugation, or the like. Alternatively, the classification operation may be performed after drying.The toner base of the toner according to an embodiment of the present invention is produced in this manner.

[0096] -Step of mixing external additive and sieving aggregate (mixing / sieving step)-For adjusting the powder characteristics and charging characteristics required for the toner, the toner base thus obtained was mixed with fine particles of silica dioxide, titanium oxide, or the like (external additive), and aggregates that are generated during mixing are removed by sieving.As the external additive mixer, a stirring mixer is preferably used. Examples of the stirring mixer include, but are not limited to, a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.), a SUPERMIXER (manufactured by Kawata Mfg. Co., Ltd.), and a TSK mixer (manufactured by Tsukishima Kikai Co., Ltd.).

[0097] (Developer)The toner according to an embodiment of the present invention can be used as a developer by mixing with a carrier or the like. In other words, the developer includes the toner according to an embodiment of the present invention, and may include other components, such as a carrier,which are appropriately selected as necessary. When the developer is used, it is possible to form an underlying layer with excellent fixing property on the surface of a fabric.

[0098] The developer may be either a one-component developer or a two-component developer. However, when the developer is used in a high-speed printer that corresponds to the recent improvement in information processing speed, or the like, a two-component developer is preferable from the viewpoint of improving the life span.

[0099] When the toner according to an embodiment of the present invention is used as a one- component developer, there is little variation in the particle size of the toner even when the toner is fed and consumed, there is little filming of the toner on the developing roller, and there is little adhesion of the toner to a member such as a blade that thins the toner layer. Further, even when the toner is stirred for a long period of time in the developing device, good, stable developability and images can be obtained.

[0100] The toner according to an embodiment of the present invention is mixed with a carrier to provide a two-component developer, which can be used in the electrophotographic image forming method with two-component developing method. When the toner according to one embodiment of the present invention is used as the two-component developer, there is little variation in the particle size of the toner even when the toner is fed and consumed over a long period of time, and even when the toner is stirred for a long period of time in the developing device, good, stable developability and images can be obtained.

[0101] As a developing method, a premix developing method may be adopted. This method replenishes a premix developer in which the toner and the carrier are mixed in advance. In the premix developing method, the increased amount of the carrier in the developing device is discharged as excess developer. This gradually renews the developer in the developing device. This makes it possible, for example, to extend the replacement cycle due to deterioration of the developer and to eliminate the effort required for replacing the developer.

[0102] <Magnetic material>When the two-component developing method is used, magnetic fine particles used as a magnetic carrier are not particularly limited and can be appropriately selected according to the purpose. Examples thereof include, but are not limited to, a spinel ferrite such as iron powder, magnetite, or gamma iron oxide, a spinel ferrite including one or more metals other than iron (Mn, Ni, Zn, Mg, Cu, etc.), a magnetoplumbite-type ferrite such as barium ferrite, and iron or alloy particles having an oxide layer on the surface. Of these, white magnetic fine particles are preferable in terms of color tone. The shape of the magnetic fine particles may be granular,spherical, or needle-like. In particular, when it is desired to strongly magnetize the magnetic carrier, it is preferable to use ferromagnetic fine particles such as iron fine particles.

[0103] Further, in consideration of chemical stability, it is preferable to use magnetite, a spinel ferrite including gamma iron oxide, or a magnetoplumbite-type ferrite such as barium ferrite. Specifically, MFL-35S, MFL-35HS (manufactured by Powdertech), DFC-400M, DFC-410M, SM-350NV (manufactured by Dowa Iron Powder Industries Co., Ltd.), and the like are preferable.

[0104] A resin carrier with the desired magnetization can be used by selecting the type and content of the ferromagnetic fine particles (carrier). For example, as the magnetic properties of the resin carrier, the magnetization strength at 1,000 Oersted is preferably 30 to 150 emu / g.Such a resin carrier can be produced by spraying the molten kneaded product of the magnetic fine particles and the insulating binder resin with a spray dryer, or by reacting and curing a monomer or a prepolymer in an aqueous medium in the presence of the magnetic fine particles, thereby dispersing the magnetic fine particles (carrier) in a condensation type binder.

[0105] The chargeability of the magnetic carrier can be controlled by adhering positively or negatively charged particles or conductive particles to the surface of the magnetic carrier, or by coating the surface of the magnetic carrier with a resin.As a surface coating material (resin), a silicone resin, an acrylic resin, an epoxy resin, a fluorine-based resin, or the like can be used. Further, the coating may be performed by including the positively or negatively charged particles or the conductive particles. Of these, a silicone resin and an acrylic resin are preferable.

[0106] In the present disclosure, the mass ratio of the carrier in the developer stored in the developing device is preferably 85% by mass or more and less than 98% by mass. When the mass ratio of the carrier in the developer is 85% by mass or more, toner scattering from the developing device is less likely to occur, and the occurrence of defective images can be reduced. When the mass ratio of the carrier in the developer is less than 98% by mass, the charge amount of the electrophotographic developing toner can be prevented from increasing excessively, and the supply amount of the electrophotographic developing toner can be prevented from being insufficient, making it possible to reduce the occurrence of defective images due to a decrease in image density.

[0107] The volume average particle size of the magnetic carrier is preferably 50 pm or more and 80 pm or less. In the image forming method according to an embodiment of the present invention, it is preferable to perform developing with the toner having a larger particle size inone pass. When the volume average particle size of the magnetic carrier is 50 pm or more, the occurrence of carrier adhesion, in which the magnetic carrier is developed together with the toner, can be prevented. When the volume average particle size is 80 pm or less, the surface area of the magnetic carrier is prevented from becoming small, a sufficient amount of toner can be held on the magnetic carrier surface, and a decrease in the amount of development, toner scattering, and background staining can be prevented.

[0108] (Transfer sheet)The toner and the toner set according to embodiments of the present invention are a toner and a toner set used to form a thermal transfer print sheet. The thermal transfer print sheet is a transfer sheet on which an image is formed using the toner or the toner set, and is used to transfer the image to a transfer object by thermal transfer.

[0109] The transfer sheet may be referred to as a transfer substrate or a substrate for transfer. The thermal transfer may be referred to as a thermal transfer printing. The thermal transfer print sheet may be referred to as a color image medium, and the color image medium is a transfer sheet on which a color image is printed. The image formed on the transfer sheet may be referred to as an image for transfer. The image for transfer may be referred to as a color toner layer or a transfer material adhering toner layer.

[0110] The transfer sheet can be appropriately selected, as long as it can transfer an image as the thermal transfer print sheet when thermal transfer is performed to the transfer object. It is preferable that the transfer sheet has good releasability of the image to be transferred. [OH l]Examples of the preferable transfer sheet include a transfer sheet in which a transfer layer including at least a thermoplastic elastomer and a higher fatty acid is formed on a substrate such as a paper or heat-resistant plastic film sheet. When a release layer of the thermoplastic elastomer is formed on the top layer of the image, the durability of the image on the transfer object is improved. Further, when the higher fatty acid is included, the higher fatty acid melts during thermal transfer and diffuses into the color toner layer and the transfer material adhering toner layer that are formed at the same time, thereby further improving the flexibility of the layers.

[0112] The color image formed on the transfer sheet (transfer substrate) is a mirror image of the original image, which has been inverted left to right. After being thermally transferred and printed to the transfer object, the image is again inverted left to right to complete the desired image. Similarly, when an additional image is overlaid on the thermal transfer print sheet, a mirror image that has been inverted left to right from the original image is overlaid.

[0113] For forming the mirror image that has been inverted left and right, mirror image information that has been inverted left and right in advance on a PC or the like is printed. In the case of an image forming apparatus with a scanner function, the original image may be scanned and then an inverted image may be output, or a mirror image that has been already inverted left and right may be scanned.

[0114] (Transfer object)An image forming method according to an embodiment of the present invention is an image forming method capable of printing on transfer objects of a wider variety of materials and shapes compared to transfer objects performed by direct printing. The image forming method according to an embodiment of the present invention may be referred to as a thermal transfer print sheet image forming method. The transfer object may be referred to as a transfer material, a transfer substrate, or a recording medium.

[0115] The transfer object can be appropriately selected, and is preferably not a thermoplastic material that is excessively deformed by heat and pressure transfer. Examples of the transfer object include various materials such as a paper, plastic, a fabric, leather, ceramic, glass, metal, and a coated surface such as a paint surface.

[0116] In particular, the thermal transfer print sheet obtained according to embodiments of the present invention is suitable for use in the field of garment printing.The garment is made of, for example, cotton, polyester, polyurethane, nylon, rayon, silk, wool, or a mixture of these fibers. Embodiments of the present invention makes it possible to form a high-quality, highly saturated image on a flexible and stretchable transfer object while retaining resistance to cracking and washability.Further, since the image can follow the deformation of a highly flexible transfer object such as leather, it is possible to obtain a highly durable image.

[0117] For the above reasons, the transfer object is preferably a fabric. For example, embodiments of the present invention are preferably used for a fabric such as a T-shirt, and can form an image, on the fabric, which has good washing fastness and good image quality. The fabric is preferably made of a cotton, polyester, nylon, rayon, or silk fiber, or a mixture of these fibers. In this case, the above-mentioned effects can be obtained.

[0118] The toner according to an embodiment of the present invention includes the polyurethane elastomer, thus it is possible to form a high-strength image, and the image has sufficient image durability even when formed on metal, ceramic, glass, or a coated surface such as a paint surface. Further, when the toner according to an embodiment of the present invention includes a sufficient proportion of the polyurethane elastomer, the above-mentioned strengthand image durability effects are improved. Further, embodiments of the present invention can facilitate custom design and labeling of tableware such as a mug, a cup, or a plate, an accessory, various tools, an automobile part, a machine tool part, furniture, a signboard, and the like.

[0119] (Image forming method, image forming apparatus, and process cartridge)Next, an image forming method, an image forming apparatus, and a process cartridge according to embodiments of the present invention are described.

[0120] The image forming method according to an embodiment of the present invention is an image forming method using the toner according to an embodiment of the present invention or the toner set according to an embodiment of the present invention, which is characterized by including an electrostatic latent image forming step of forming an electrostatic latent image on an electrostatic latent image bearer of the image forming apparatus, a developing step of developing the electrostatic latent image to form a toner image, a transfer step of transferring the toner image to the transfer sheet, and a fixing step of fixing the toner image to the transfer sheet to produce the thermal transfer print sheet through the fixing step.

[0121] The image forming apparatus according to an embodiment of the present invention is an image forming apparatus including the toner according to an embodiment of the present invention or the toner set according to an embodiment of the present invention, which is characterized by including an electrostatic latent image bearer, an electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image bearer, a developing means for developing the electrostatic latent image to form a toner image, a transfer means for transferring the toner image to the transfer sheet, and a fixing means for fixing the toner image to the transfer sheet to produce the thermal transfer print sheet through fixation by the fixing means.

[0122] The process cartridge according to an embodiment of the present invention is a process cartridge that includes the toner according to an embodiment of the present invention and is detachable from an image forming apparatus including a fixing means, which is characterized by including an electrostatic latent image bearer, an electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image bearer, a developing means for developing the electrostatic latent image to form a toner image, and a transfer means for transferring the toner image to a transfer sheet. When the process cartridge is attached to the image forming apparatus, the fixing means fixes the toner image to the transfer sheet to produce a thermal transfer print sheet.

[0123] The image forming method according to an embodiment of the present invention may be referred to as a printing method, a print method, an image output method, or an electrophotographic output method. The image forming apparatus according to an embodiment of the present invention may be referred to as a printing apparatus, a printer, an image output apparatus, or an electrophotographic output apparatus. The image forming method can be suitably performed by the image forming apparatus, the electrostatic latent image forming step can be suitably performed by the electrostatic latent image forming means, the developing step can be suitably performed by the developing means, and the other steps can be suitably performed by the other means.

[0124] Further, the image forming method according to an embodiment of the present invention may include a thermal transfer step of thermally transferring the image on the thermal transfer print sheet to the transfer object. In the thermal transfer step, it is preferable that the thermal transfer print sheet contacts the transfer object while heat and pressure are applied. Applying heat and pressure can improve fixation to the transfer object and image durability.

[0125] The image forming method according to an embodiment of the present invention preferably forms a single-layer toner image, on the thermal transfer print sheet, in which the toner image does not overlap with any other toner image. By forming the toner layer as a single layer, it is expected to simplify the process and reduce the costs. As described above, when the toner according to an embodiment of the present invention is the above-mentioned toner (C) including a white pigment and a colorant, the toner according to an embodiment of the present invention has low transparency (the above-mentioned transmittance is less than 5%), making it difficult to achieve full color expression using a subtractive color method as is the case with a general electrophotographic color toner. Thus, it is preferable that the colorants are mixed in advance and included in the toner to form each toner layer as a single layer. In this case, there is no need to overlap the toner layers, and the above-mentioned effects can be obtained.

[0126] The image forming apparatus according to an embodiment of the present invention is, for example, an apparatus including multiple developing stations, and is equipped with the toner or toner set according to an embodiment of the present invention. At each developing station, it is preferable to form a toner layer having a thickness of 15 pm or more in one pass. However, if the sufficient deposition amount cannot be obtained, the same toner may be used at multiple developing stations, or the number of printing passes may be increased to form an image.

[0127] The required toner deposition amount varies depending on the material, brightness, and the like of the transfer object (which may also be referred to as a transfer substrate, or a transfer material). In a case of the smooth transfer object, having a toner layer thickness of 15 pm ormore can prevent a decrease in saturation of the color image and obtain a clear image, even if the image is formed on a dark color (low brightness) transfer object. Further, having a toner layer thickness of 30 pm or more can obtain an even clearer color image. When the thickness of the toner layer is 100 pm or less, the setting of fixing conditions for preventing hot offset and cold offset can be prevented from becoming difficult, making it easy to obtain stable quality. In the image formation according to an embodiment of the present invention, it is not necessary to overlap different toners. Thus, the desired design can be printed without the need to overlap toners to the extent that causes the deposition amount to be excessive.

[0128] All of the multiple developing stations may use different color toners, or the same color toner may be used in the multiple developing stations. The color combination is selected according to the purpose. For multi-color printing, using different color toners in each station reduces the frequency of color changes and increases efficiency. For printing with two colors or less, a single color toner may be used in the multiple developing stations. For example, a first color toner is used in the first and second developing stations, and a second color toner is used in the third and fourth developing stations. In this manner, the toner deposition amount of each color can be printed with fewer print runs. Further, a single color toner may be used in all of the developing stations, and by doing so, the sufficient deposition amount of each color can be printed with one print run. Further, in this case, toner color changes are not necessary, further increasing efficiency. However, since this results in increased equipment costs and installation space, it is preferable to select the color combination according to the purpose and use.

[0129] <Example of image forming apparatus and image forming method>Examples of the image forming apparatus and image forming method according to embodiments of the present invention are described.

[0130] <Electrostatic latent image bearer>The structure, size, and the like of the electrostatic latent image bearer are not particularly limited, and the electrostatic latent image bearer can be appropriately selected from known ones. The shape of the electrostatic latent image bearer is not particularly limited and can be appropriately selected depending on the purpose. Examples of the shape include, but are not limited to, a drum shape and a belt shape. The material of the electrostatic latent image bearer is not particularly limited and can be appropriately selected depending on the purpose. Examples of the material include, but are not limited to, an inorganic photoconductor such as amorphous silicon and selenium, and an organic photoconductor (OPC) such as polysilane and phthalopolymethine.

[0131] Examples of the organic photoconductor include a laminated photoconductor having a laminated structure in which a layer (charge generation layer) in which a charge generation material such as metal-free phthalocyanine or titanyl phthalocyanine is dispersed in a binder resin and a layer (charge transport layer) in which a charge transport material is dispersed in a binder resin are stacked on a support such as an aluminum drum, and a single-layer photoconductor having a single-layer structure photoconductor layer, on a support, in which both a charge generation material and a charge transport material are dispersed in a binder resin.In the single-layer photoconductor, a hole transport agent and an electron transport agent may be added to the photoconductor layer as charge transport materials.Further, an undercoat layer may be provided between the support and the laminated charge generation layer or the single-layer photoconductor layer.

[0132] The shape of the electrostatic latent image bearer is not particularly limited and can be appropriately selected depending on the purpose. However, a cylindrical shape is preferable. The outer diameter of the cylindrical electrostatic latent image bearer is not particularly limited and can be appropriately selected depending on the purpose. However, the outer diameter is preferably 3 mm to 100 mm, particularly preferably 20 mm to 50 mm.

[0133] <Electrostatic latent image forming means and electrostatic latent image forming step> The electrostatic latent image forming means is not particularly limited and can be appropriately selected according to the purpose, as long as it is a means for forming the electrostatic latent image on the electrostatic latent image bearer. Examples thereof include, but are not limited to, a means including at least a charging member for charging the surface of the electrostatic latent image bearer and an exposure member for exposing the surface of the electrostatic latent image bearer to light in an image pattern.The electrostatic latent image forming step is not particularly limited and can be appropriately selected according to the purpose, as long as it is a step for forming the electrostatic latent image on the electrostatic latent image bearer. For example, this step can be performed by charging the surface of the electrostatic latent image bearer and then exposing the surface to light in an image pattern. The step can be performed using the electrostatic latent image forming means.

[0134] -Charging member and charging-The charging means includes, for example, a charging member that charges the electrostatic latent image bearer.The charging member is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include, but are not limited to, a known contact chargerequipped with a conductive or semiconductive roller, brush, film, rubber blade, or the like and a non-contact charger that utilizes corona discharge such as a corotron or a scorotron.The charging (charging step) can be performed, for example, by applying a voltage to the surface of the electrostatic latent image bearer using the charging member.

[0135] The shape of the charging member may be in any form such as a roller, a magnetic brush, or a fur brush, and may be selected according to a specification and form of the image forming apparatus.The charging member is not limited to the contact charging member. However, it is preferable to use the contact charging member, as this can result in the image forming apparatus in which the amount of ozone generated by the charging member is reduced.

[0136] -Exposure member and exposure-The exposure means includes, for example, an exposure member that exposes the electrostatic latent image bearer to light.The exposure member is not particularly limited and can be appropriately selected depending on the purpose, as long as it can expose the surface of the electrostatic latent image bearer charged by the charging member to light in an image pattern to be formed. Examples of the exposure member include, but are not limited to, various exposure members such as a copying optical system, a rod lens array system, a laser optical system, and a liquid crystal shutter optical system.

[0137] A light source used in the exposure member is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include, but are not limited to, light-emitting materials in general, such as a fluorescent lamp, a tungsten lamp, a halogen lamp, a mercury lamp, a sodium lamp, a light-emitting diode (LED), a semiconductor laser (LD), and an electroluminescence (EL).Further, various filters such as a sharp-cut filter, a band-pass filter, a near-infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can be used to apply only light in the desired wavelength range.

[0138] The exposure (exposure step) can be performed, for example, by exposing the surface of the electrostatic latent image bearer to light in an image pattern using the exposure member. Note that, in the present disclosure, a back lighting system in which the exposure is performed in an image pattern from the back side of the electrostatic latent image bearer may be adopted.

[0139] <Developing means and developing step>The developing means is not particularly limited and can be appropriately selected according to the purpose, as long as it is a developing means equipped with the toner, which developsthe electrostatic latent image formed on the electrostatic latent image bearer to form a toner image. The toner image is an image that is transferred to the transfer object, thus it may be referred to as a transfer material adhering image. Further, the toner may be referred to as a transfer material adhering toner from the viewpoint that it is used to form the transfer material adhering image. The toner image may be referred to as the transfer material adhering image.

[0140] The developing step is not particularly limited and can be appropriately selected depending on the purpose, as long as it is a step in which the electrostatic latent image formed on the electrostatic latent image bearer is developed using the toner to form a visible image. For example, it can be performed by the developing means described above.

[0141] As the developing means, a developing device including an agitator that charges the toner by friction agitation, a magnetic field generating means fixed inside, and a rotatable developer carrier that carries a developer including the toner on its surface is preferable.

[0142] In the developing means, for example, the toner and the carrier are mixed and stirred, and the toner becomes charged by friction during this process and is held in a standing state on the surface of the rotating magnet roller, thereby forming a magnetic brush. The magnet roller is disposed near the electrostatic latent image bearer. Thus, a portion of the toner constituting the magnetic brush formed on the surface of the magnet roller moves to the surface of the electrostatic latent image bearer by electrical attraction. As a result, the electrostatic latent image is developed by the toner, and a visible image (toner image) made of the toner is formed on the surface of the electrostatic latent image bearer.

[0143] <Transfer means and transfer step>The transfer means is not particularly limited and can be appropriately selected according to the purpose, as long as it is a means capable of performing transferring. The transfer means may use a primary transfer method in which the toner image is transferred to the transfer object, or a secondary transfer method in which the toner image is transferred to an intermediate transfer object and then transferred to the transfer object. As the transfer means, for example, those having a primary transfer means for transferring the toner image onto the intermediate transfer object to form a composite transfer image, and a secondary transfer means for transferring the composite transfer image onto the transfer object are preferable.

[0144] The transfer step is not particularly limited and can be appropriately selected according to the purpose, as long as it is a step capable of performing transferring. The transfer step may use a primary transfer method in which the toner image is transferred to the transfer object, or a secondary transfer method in which the toner image is transferred to an intermediate transfer object and then transferred to the transfer object. As the transfer step, for example, a step inwhich an intermediate transfer object is used, and the toner image is primarily transferred onto the intermediate transfer object, and then the toner image is secondarily transferred onto the transfer object is preferable.In the transfer step, the toner image can be transferred, for example, by charging the electrostatic latent image bearer using a transfer charger, and the transfer step can be performed by the transfer means.

[0145] When the image to be secondarily transferred onto the transfer object is an image formed of two types of toners, a transparent toner and a white toner, the transfer may be performed as follows. That is, the toner images may be sequentially stacked on the intermediate transfer object to form an image to be transferred, and the image on the intermediate transfer object may be secondarily transferred as a whole to the transfer object.Note that the intermediate transfer object is not particularly limited and can be appropriately selected from known transfer objects according to the purpose. For example, a transfer belt or the like can be preferably mentioned.

[0146] The transfer means (the primary transfer means and the secondary transfer means) preferably includes at least a transfer unit that releases by charging the visible image (toner image) formed on the electrostatic latent image bearer to the side of the transfer sheet.

[0147] Examples of the transfer unit include, but are not limited to, a corona transferrer that uses corona discharge, a transfer belt, a transfer roller, a pressure transfer roller, and an adhesion transferrer.

[0148] The transfer sheet is not particularly limited and can be selected appropriately according to the purpose, as long as it is capable of transferring the developed toner image and transferring the image on the transfer sheet to the transfer object. Examples of the transfer sheet that can be used include, but are not limited to, a transfer paper sheet having a transfer layer, and a release paper sheet or release film having a release layer.

[0149] <Fixing means and fixing step>After the toner image is transferred to the transfer sheet, the fixing step is performed to produce a thermal transfer print sheet. The fixing step can be performed by the fixing means. The fixing means is not particularly limited and can be appropriately selected according to the purpose, as long as it is a means for fixing the toner image transferred to the transfer sheet. However, a known heating and pressing member is preferable. Examples of the heating and pressing member include, but are not limited to, a combination of a heating roller and a pressing roller, and a combination of a heating roller, a pressing roller, and an endless belt.

[0150] The fixing step is not particularly limited and can be appropriately selected according to the purpose, as long as it is a step for fixing the toner image transferred to the transfer sheet. The fixing step is characterized in that the fixing is performed simultaneously at once to the toner images stacked by each color developing means.

[0151] The heating temperature of the heating and pressing member is preferably 80°C to 200°C. Note that, in the present disclosure, depending on the purpose, for example, a known optical fixing device may be used together with or instead of the fixing means. The surface pressure in the fixing step is not particularly limited and can be appropriately selected depending on the purpose. However, it is preferably 10 N / cm2to 80 N / cm2.

[0152] <Other means and other steps>Examples of the other means include, but are not limited to, a cleaning means, a discharging means, a recycling means, and a control means.Examples of the other steps include, but are not limited to, a cleaning step, a discharging step, a recycling step, and a control step.

[0153] -Cleaning means and cleaning step-The cleaning means is not particularly limited and can be appropriately selected depending on the purpose, as long as it is a means capable of removing the toner remaining on the photoconductor. Examples thereof include, but are not limited to, a magnetic brush cleaner, an electrostatic brush cleaner, a magnetic roller cleaner, a blade cleaner, a brush cleaner, and a web cleaner.The cleaning step is not particularly limited and can be appropriately selected depending on the purpose, as long as it is a step capable of removing the toner remaining on the photoconductor, and can be performed, for example, by the cleaning means.

[0154] -Discharging means and discharging step-The discharging means is not particularly limited and can be appropriately selected depending on the purpose, as long as it is a means for discharging the photoconductor by applying a discharging bias. For example, a discharging lamp or the like can be mentioned.The discharging step is not particularly limited and can be appropriately selected depending on the purpose, as long as it is a step for discharging the photoconductor by applying a discharging bias. For example, the discharging step can be performed by the discharging means.

[0155] -Recycling means and recycling step-The recycling means is not particularly limited and can be appropriately selected depending on the purpose, as long as it is a means for recycling the toner removed in the cleaning step in the developing device. For example, a known conveying means or the like can be mentioned. The recycling step is not particularly limited and can be appropriately selected depending on the purpose, as long as it is a step for recycling the toner removed in the cleaning step in the developing device. For example, the recycling step can be performed by the recycling means.

[0156] -Control means and control step-The control means is not particularly limited and can be appropriately selected depending on the purpose, as long as it is a means capable of controlling the movement of each of the means. For example, equipment such as a sequencer or a computer, or the like can be mentioned.The control step is not particularly limited can be appropriately selected depending on the purpose, as long as it is a step capable of controlling the movement of each of the steps. For example, the control step can be performed by the control means.

[0157] <Detailed example of image forming apparatus and image forming method>Next, examples of the image forming apparatus and the image forming method are described with reference to FIG. 1.An image forming apparatus 100 A illustrated in FIG. 1 includes a photoconductor drum 10 (hereinafter sometimes referred to as “photoconductor 10”) as the electrostatic latent image bearer, a charging roller 20 as the charging means, an exposure device 30 as the exposure means, a developing device 40 as the developing means, an intermediate transfer object 50, a cleaning device 60, as the cleaning means, having a cleaning blade, and a discharging lamp 70 as the discharging means.

[0158] The intermediate transfer object 50 is an endless belt, and is designed to be movable in an arrow direction by three rollers 51 disposed inside the loop of the belt and stretching the belt. Some of the three rollers 51 also function as transfer bias rollers capable of applying a predetermined transfer bias (primary transfer bias) to the intermediate transfer object 50. A cleaning device 90 having a cleaning blade is disposed near the intermediate transfer object 50. Further, a transfer roller 80, as the transfer means, capable of applying a transfer bias for transferring (secondary transfer) the toner image to a transfer sheet 95 as a recording medium is disposed so as to face the intermediate transfer object 50 near the intermediate transfer object 50. A corona charger 58 for applying a charge to the toner image on the intermediate transfer object 50 is disposed around the intermediate transfer object 50, between a contact part between the photoconductor 10 and the intermediate transfer object 50 and a contact part between the intermediate transfer object 50 and the transfer sheet 95 in the rotation direction of the intermediate transfer object 50.

[0159] Note that, in the present embodiment, an elastic intermediate transfer belt can also be used as the intermediate transfer object 50. For example, the elastic intermediate transfer belt can be used in which a flexible elastic layer is stacked on a rigid base layer that provides certain flexibility.Further, a deviation preventing guide member may be provided on the inner peripheral surface of the intermediate transfer object 50 to prevent the intermediate transfer object 50 from meandering.

[0160] An example in which a black (K) is used as the first color, a yellow (Y) as the second color, a magenta (M) as the third color, and a cyan (C) as the fourth color is described below. The colors are not limited to these colors.

[0161] The developing device 40 is constituted by a developing belt 41 as a developer carrier, and developing units 45K, 45Y, 45M, and 45C arranged around the developing belt 41.For example, the developing unit 45K includes a developer container 42K, a developer supply roller 43K, and a developing roller 44K. The same applies for the developing units 45 Y, 45M, and 45C.Further, the developing belt 41 is an endless belt that is rotatably stretched around multiple belt rollers, and a part of the belt is in contact with the photoconductor 10.

[0162] In the image forming apparatus 100 A illustrated in FIG. 1, for example, the charging roller 20 uniformly charges the photoconductor drum 10. The exposure device 30 exposes the photoconductor drum 10 to light in an image pattern, thereby forming an electrostatic latent image. The electrostatic latent image formed on the photoconductor drum 10 is developed by supplying the toner from the developing device 40 to form a toner image. The toner image is transferred (primary transfer) onto the intermediate transfer object 50 by the voltage applied from the roller(s) 51, and further transferred (secondary transfer) onto the transfer sheet 95. As a result, a transfer image is formed on the transfer sheet 95. Note that the remaining toner on the photoconductor 10 is removed by the cleaning device 60, and the charge on the photoconductor 10 is temporarily removed by the discharging lamp 70.

[0163] FIG. 2 illustrates another example of the image forming apparatus according to an embodiment of the present invention. An image forming apparatus 100B has the same configuration as the image forming apparatus 100 A illustrated in FIG. 1, except that it does not include the developing belt 41, and the developing units 45K, 45 Y, 45M, and 45C are disposed directly around the photoconductor drum 10 so as to face the photoconductor drum 10.

[0164] FIG. 3 illustrates yet another example of the image forming apparatus according to an embodiment of the present invention. The image forming apparatus illustrated in FIG. 3 includes a copying device main body 150, a paper feed table 200, a scanner 300, and an automatic document feeder (ADF) 400.

[0165] The copying device main body 150 includes an endless belt-like intermediate transfer object 50 in the center.The intermediate transfer object 50 is stretched over support rollers 14, 15, and 16, and can rotate clockwise in FIG. 3. An intermediate transfer object cleaning device 17 for removing the remaining toner on the intermediate transfer object 50 is disposed near the support roller 15. A tandem type developing device 120 is disposed along the conveying direction of the intermediate transfer object 50 stretched over the support rollers 14 and 15 so as to face four image forming means 18, namely, a first, second, third, and fourth image forming means, which are arranged side by side. An exposure device 21, which is the exposure member, is disposed near the tandem type developing device 120.

[0166] A secondary transfer device 22 is disposed, with respect to the intermediate transfer object 50, on a side opposite to the side where the tandem type developing device 120 is disposed. In the secondary transfer device 22, an endless secondary transfer belt 24 is stretched over a pair of rollers 23, and the transfer sheet transported on the secondary transfer belt 24 and the intermediate transfer object 50 can come into contact with each other. A fixing device 25, which is the fixing means, is disposed near the secondary transfer device 22. The fixing device 25 includes an endless fixing belt 26 and a pressure roller 27 that is disposed so as to be pressed by the fixing belt 26.

[0167] Note that, in this tandem image forming apparatus, a sheet inverting device 28 is disposed near the secondary transfer device 22 and the fixing device 25 to invert the transfer sheet for forming images on both sides of the transfer sheet.

[0168] Next, formation of a transfer material adhering image using the tandem type developing device 120 is described. Specifically, first, an original document is placed on a platen 130 of the automatic document feeder (ADF) 400, or the automatic document feeder 400 is opened, an original document is placed on a contact glass 32 of the scanner 300, and the automatic document feeder 400 is closed.

[0169] Upon pressing a start switch, when the original document is set to the automatic document feeder 400, the scanner 300 is driven after the original document is transported and moved onto the contact glass 32. On the other hand, when the original document is set on the contact glass 32, the scanner 300 is driven immediately. Then, a first travel body 33 and a secondtravel body 34 start traveling. At this time, light is applied from the light source by the first travel body 33, and the reflected light from the original document surface is reflected by a mirror on the second travel body 34. The reflected light is received by a reading sensor 36 through an imaging lens 35, so that the original color document (color image) is read and converted into image information of a first color, a second color, a third color, and a fourth color, thereby forming a solid image in which all colors are deposited in the same amount.

[0170] Then, the solid image information is transmitted to each image forming means 18 in the tandem developing devices 120. Then, in each image forming means, an image that is uniform in all of the image forming means is formed by each image forming means. In this example, the image forming means 18 are provided corresponding to each of K, Y, M, and C.

[0171] FIG. 4 is a diagram describing each image forming means 18 in the tandem developing device 120.As illustrated in FIG. 4, the image forming means 18 includes an electrostatic latent image bearer 10, a charging device 160, a developing device 61, a transfer charger 62, a cleaning device 63, and a discharging device 64 for each of K, Y, M, and C.

[0172] The charging device 160 is the charging means for uniformly charging the photoconductor 10. For example, the exposure device exposes the photoconductor 10 to light (L) in a form of image corresponding to the solid image based on the solid image information, thereby forming an electrostatic latent image corresponding to the image on the electrostatic latent image bearer. The developing device 61 is the developing means for developing the electrostatic latent image using each toner to form a toner image. The transfer charger 62 transfers the toner image onto the intermediate transfer object 50. The cleaning device 63 cleans the photoconductor 10. The discharging device 64 eliminates charging of the photoconductor 10.

[0173] Note that each image forming means 18 may be referred to as a first to fourth image forming means corresponding to K, Y, M, and C. Similarly, each photoconductor 10 may be referred to as a first to fourth photoconductor 10 corresponding to K, Y, M, and C.

[0174] Then, each image forming means 18 forms a single-color image (first to fourth color images) based on the image information of each color. The first to fourth color images thus formed are sequentially transferred (primary transfer) onto the intermediate transfer object 50, which is rotated and moved by the support rollers 14, 15, and 16. In this manner, a color image is synthesized on the intermediate transfer object 50.

[0175] On the other hand, in the paper feed table 200, one of paper feed rollers 142 is selectively rotated to feed a transfer sheet from one of paper feed cassettes 144 provided in multiple stages in a paper bank 143. The transfer sheets are separated one by one by a separation roller 145, fed to a paper feed path 146, conveyed by a transport roller 147, and guided to a paper feed path 148 inside the copying device main body 150, where the transfer sheets stop while contacting a registration roller 49. Alternatively, a paper feed roller 142 is rotated to feed the transfer sheet on a manual feed tray 54. The transfer sheets are separated one by one by a separation roller 52 and sent to a manual feed path 53, where they also stop while contacting the registration roller 49.

[0176] Note that the registration roller 49 is generally grounded when used. However, the registration roller 49 may also be used while it is applied with a bias for removing paper dust from the transfer sheet.

[0177] Then, the registration roller 49 is rotated in synchronization with the color image synthesized on the intermediate transfer object 50 to send the transfer sheet to between the intermediate transfer object 50 and the secondary transfer device 22, thereby transferring (secondary transfer) the color image onto the transfer sheet by the secondary transfer device 22. In this manner, the color image is transferred and formed on the transfer sheet. Note that the remaining toner on the intermediate transfer object 50 after the image transfer is cleaned by the intermediate transfer object cleaning device 17. Further, a collecting means for receiving the toner and the like removed by the intermediate transfer object cleaning device 17 may be provided. A dish-shaped tray or the like can be used as the collecting means.

[0178] The transfer sheet onto which the color image has been transferred is conveyed by the secondary transfer device 22 and sent to the fixing device 25, where the color image (transfer material adhering transfer image) is fixed onto the transfer sheet by heat and pressure. Then, the transfer sheet is switched by a switching claw 55, discharged by a discharge roller 56, and stacked on a paper output tray 57. Alternatively, the sheet is switched by the switching claw 55, inverted by the sheet inverting device 28, and guided back to the transfer position. After an image is recorded on the back side, the sheet is discharged by the discharge roller 56 and stacked on the paper output tray 57.

[0179] <Example of process cartridge>A process cartridge according to an embodiment of the present invention is molded so as to be detachable from various image forming apparatuses, and includes at least an electrostatic latent image bearer that bears an electrostatic latent image, and a developing means that develops the electrostatic latent image borne on the electrostatic latent image bearer with adeveloper to form a toner image. Note that the process cartridge according to an embodiment of the present invention may further include other means as necessary.

[0180] The developing means includes, for example, a developer container that contains a developer, and a developer carrier that carries and transports the developer contained in the developer container. The developing means may further include a regulating member for regulating the thickness of the developer carried, or the like.

[0181] FIG. 5 illustrates an example of the process cartridge according to an embodiment of the present invention. A process cartridge 110 includes a photoconductor drum 10, a corona charger 58, a developing device 40, a transfer roller 80, and a cleaning device 90.

[0182] The photoconductor drum 10 is an example of the electrostatic latent image bearer. The corona charger 58 is an example of the charging means and charges the photoconductor drum 10. Exposure light L is applied onto the photoconductor drum 10 to form an electrostatic latent image on the photoconductor drum 10. The developing device 40 is an example of the developing means and performs development. The transfer roller 80 is an example of a transfer unit and transfers the toner image to the transfer sheet. The cleaning device 90 is an example of the cleaning means and cleans the photoconductor drum 10.

[0183] (Thermal transfer device)The transfer step, in which an image to be transferred formed on the thermal transfer print sheet is transferred to the transfer object by thermal transfer, can be performed, for example, by a thermal transfer device.The thermal transfer device is a device that thermally transfers the thermal transfer print sheet to the transfer object such as a fabric or leather, and the thermal transfer device can apply heat on a press surface for a certain period of time with uniform pressure. The thermal transfer device is also referred to as an iron press machine or a heat press machine.

[0184] The thermal transfer device used in the present disclosure may be any device that is commercially available. When transferring is performed to the transfer object such as a T- shirt, it is preferable that the area of the press surface is larger than the area of the transfer object. By uniformly applying heat and pressure to the front surface of the transfer object, a transfer image can be obtained without leaving a press mark on the transfer object. Specific examples of the thermal transfer device include, but are not limited to, GFH-380, GHP-300 (all from SystemGraphi Co., Ltd.), HPT234PS1, HSP-5400, HP-4536A-12, HP-54A, HP- 84A, HSP-1513PV-AT, HSP-1010 (all from HASHIMA), TS-ONE (Siser S.r.l.), and TP630M, TP700A (Horizon International Inc.).

[0185] The temperature for thermal transfer can be appropriately selected depending on the material, thickness, and the like of the transfer object. The temperature is higher than the softening point Ts of the toner and is preferably 20°C minus of the heat resistance temperature Th of the transfer object.The pressure for thermal transfer is preferably a low pressure, as long as transfer is possible. For example, the pressure is preferably 1000 g / cm2or less, more preferably 600 g / cm2or less, even more preferably 300 g / cm2or less.

[0186] Further, it is possible to use a commercially available iron. However, from the viewpoint of applying heat uniformly with uniform pressure, it is preferable to use the above-mentioned thermal transfer device. Further, embodiments of the present invention provide an image forming system including the above-mentioned image forming apparatus and thermal transfer device according to embodiments of the present invention.[Examples]

[0187] Embodiments of the present invention are described in more detail below with reference to examples. However, the present invention is not limited to these examples.

[0188] (Production of toner for thermal transfer print sheet)A toner (toner for thermal transfer print sheet) was produced as follows. The formulation is presented in Table 1.

[0189] <Production example of toner 1>-Raw materials for toner 1-Polyurethane elastomer ECOFREEN POWDER (manufactured by Ecofreen Co., Ltd., softening point of 120°C, glass transition temperature of -29°C) 50% by mass•Polyester resin RN-306SF (manufactured by Kao Corp., softening point of 100°C, glass transition temperature of 60°C) 20% by massWax dispersant (EXD-001, manufactured by Sanyo Chemical Industries, Ltd.) 2.5% by mass Ester wax (LW-13, manufactured by Sanyo Chemical Industries, Ltd.) 2.5% by mass •Titanium oxide white pigment (PF-739, manufactured by Ishihara Sangyo Kaisha, Ltd.) 25% by mass

[0190] The raw materials for a toner 1 were premixed using a Henschel mixer (FM20B manufactured by Nippon Coke & Engineering. Co., Ltd.), and then melted and kneaded at a temperature set at 90°C using a batch kneader (WONDER KNEADER “WD S7-30” manufactured by Moriyama Company Ltd.). The resulting kneaded product was extruded from a 3 mm diameter die using a feeder rudder to form a strand, which was then cooled in a water tank with a water temperature of 15°C or lower. The solidified strand was cut using a pelletizer.This resulted in a toner pellet 1 with a diameter of 2 mm and a length of 2 mm. This pellet is a molten kneaded toner component coarsely pulverized product.Next, the pellet was placed in a cooling machine and cooled with liquid nitrogen and then pulverized using a mechanical pulverizer (LINREX MILL LX manufactured by Hosokawa Micron Group). The pulverized product discharged from the pulverizer was sieved through a 25 pm mesh, and the non-passed portion was re-introduced into the pulverizer to obtain 25- mesh passing fine particles. The 25-mesh passing fine particles were returned to room temperature and then classified into fine particles using a jet air classifier (EJ-LABO manufactured by Matsubo Corp.) while appropriately adjusting the louver opening so that particles of 5 pm or less constituted 10% or less by number, thereby obtaining toner base particles.

[0191] Next, 100 parts by mass of the obtained toner base particles were stirred and mixed with 1.0 part by mass of an additive 1 (HDK-2000 manufactured by Clariant, substance name: silica) and 1.0 part by mass of an additive 2 (H05TD manufactured by Clariant, substance name: silica) in a Henschel mixer to produce the toner 1 (toner 1 for thermal transfer print sheet).

[0192] <Production example of toner 2> -Raw materials for toner 2- Polyurethane elastomer (E780M128 manufactured by Nippon Miractran Co, Ltd., softening point of 118°C, glass transition temperature of -24°C) 60% by mass •Polyester resin RN-306SF (manufactured by Kao Corp., softening point of 100°C, glass transition temperature of 60°C) 25% by massWax dispersant (EXD-001 manufactured by Sanyo Chemical Industries, Ltd.) 2.5% by mass Ester wax (LW-13 manufactured by Sanyo Chemical Industries, Ltd.) 2.5% by mass •Carbon black (#44 manufactured by Mitsubishi Chemical Group Corp.) 10% by mass

[0193] The raw materials for toner 2 were processed in the same manner as for the toner 1 to produce a toner 2.

[0194] <Production example of toner 3>-Raw materials for toner 3-• Polyurethane elastomer (57F manufactured by BASF, softening point of 116°C, glass transition temperature of -26.5°C) 45% by mass•Polyester resin RN-306SF (manufactured by Kao Corp., softening point of 100°C, glass transition temperature of 60°C) 20% by massWax dispersant (EXD-001 manufactured by Sanyo Chemical Industries, Ltd.) 2.5% by mass Ester wax (LW-13, manufactured Sanyo Chemical Industries, Ltd.) 2.5% by mass•Titanium oxide white pigment (PF-739 manufactured by Ishihara Sangyo Kaisha, Ltd.) 20% by mass•Pigment blue 15:3 (7919 manufactured by Toyochem Co., Ltd.) 9.5% by mass•Carbon black (#44 manufactured by Mitsubishi Chemical Group Corp.) 0.5% by mass

[0195] The raw materials for toner 3 were processed in the same manner as for the toner 1 to produce a toner 3.

[0196] <Production example of toner 4>-Raw materials for toner 4-Polyurethane elastomer (E780M128 manufactured by Nippon Miractran Co, Ltd., softening point of 118°C, glass transition temperature of -24°C) 45% by mass•Polyester resin RN-306SF (manufactured by Kao Corp., softening point of 100°C, glass transition temperature of 60°C) 20.72% by massWax dispersant (EXD-001 manufactured by Sanyo Chemical Industries, Ltd.) 2.5% by mass Ester wax (LW-13 manufactured by Sanyo Chemical Industries, Ltd.) 2.5% by mass •Titanium oxide white pigment (PF-739 manufactured by Ishihara Sangyo Kaisha, Ltd.) 20% by mass•Pigment red 254 (Irgazin Red D 3656 HD manufactured by DIC Corp.) 9.1% by mass •Carbon black (#44 manufactured by Mitsubishi Chemical Group Corp.) 0.18% by mass

[0197] The raw materials for toner 4 were processed in the same manner as the toner 1 to produce a toner 4.

[0198] <Production example of toner 5>-Raw materials for toner 5-• Polyurethane elastomer (57F manufactured by BASF, softening point of 116°C, glass transition temperature of -26.5°C) 49% by mass•Polyester resin RN-306SF (manufactured by Kao Corp., softening point of 100°C, glass transition temperature of 60°C) 20% by massWax dispersant (EXD-001 manufactured by Sanyo Chemical Industries, Ltd.) 2.5% by mass Ester wax (LW-13 manufactured by Sanyo Chemical Industries, Ltd.) 2.5% by mass •Titanium oxide white pigment (PF-739 manufactured by Ishihara Sangyo Kaisha, Ltd.) 25% by mass•Carbon black (#44 manufactured by Mitsubishi Chemical Group Corp.) 1.0% by mass

[0199] The raw materials for toner 5 were processed in the same manner as for the toner 1 to prepare a toner 5.

[0200] <Production example of toner 6>-Raw materials for toner 6-• Polyurethane elastomer (57F manufactured by BASF, softening point of 116°C, glass transition temperature of -26.5°C) 55% by mass•Polyester resin RN-306SF (manufactured by Kao Corp., softening point of 100°C, glass transition temperature of 60°C) 30% by massWax dispersant (EXD-001 manufactured by Sanyo Chemical Industries, Ltd.) 2.5% by mass Ester wax (LW-13 manufactured by Sanyo Chemical Industries, Ltd.) 2.5% by mass •Pigment blue 15:3 (7919 manufactured by Toyochem Co., Ltd.) 9.5% by mass •Carbon black (#44 manufactured by Mitsubishi Chemical Group Corp.) 0.5% by mass

[0201] The raw materials for toner 6 were processed in the same manner as for the toner 1 to prepare a toner 6.

[0202] <Production example of toner 7>-Raw materials for toner 7-Polyurethane elastomer (E780M128 manufactured by Nippon Miractran Co, Ltd., softening point of 118°C, glass transition temperature of -24°C) 55% by mass•Polyester resin RN-306SF (manufactured by Kao Corp., softening point of 100°C, glass transition temperature of 60°C) 30.72% by massWax dispersant (EXD-001 manufactured by Sanyo Chemical Industries, Ltd.) 2.5% by mass Ester wax (LW-13 manufactured by Sanyo Chemical Industries, Ltd.) 2.5% by mass •Pigment red 254 (Irgazin Red D 3656 HD manufactured by DIC Corp.) 9.1% by mass •Carbon black (#44 manufactured by Mitsubishi Chemical Group Corp.) 0.18% by mass

[0203] The raw materials for toner 7 were processed in the same manner as for the toner 1 to produce a toner 7.

[0204] <Production example of toner 8>-Raw materials for toner 8-• Polyurethane elastomer (57F manufactured by BASF, softening point of 116°C, glass transition temperature of -26.5°C) 69% by massWax dispersant (EXD-001 manufactured by Sanyo Chemical Industries, Ltd.) 2.5% by mass Ester wax (LW-13 manufactured by Sanyo Chemical Industries, Ltd.) 2.5% by mass •Titanium oxide white pigment (PF-739 manufactured by Ishihara Sangyo Kaisha, Ltd.) 25% by mass•Carbon black (#44 manufactured by Mitsubishi Chemical Group Corp.) 1.0% by mass

[0205] The raw materials for toner 8 were processed in the same manner as for the toner 1 to produce a toner 8.

[0206] (Production of carrier)-Raw materials for carrier- P solvent 710 parts by mass•ECF-800 (manufactured by Titan Kogyo, Ltd., aluminum oxide, tin oxide, phosphorus pentoxide mixed fine particles) 220 parts by mass•R5T (manufactured by Dow Toray Co., Ltd., silicone / acrylic resin / toluene solution) 40 parts by mass•RCF-2130 (manufactured by Dow Toray Co., Ltd., polyalkenylsiloxane / toluene solution) 400 parts by massCTC-754 (manufactured by Matsumoto Fine Chemical Co., Ltd., titanium isopropoxy bis(ethyl acetate)) 45 parts by mass•RSH-602 (manufactured by Dow Toray Co., Ltd., r-(2- aminoethyl)aminopropyltrimethoxysilane) 5 parts by mass

[0207] The above-mentioned raw materials were dispersed in a HOMOMIXER for 20 minutes to prepare a resin layer coating liquid. Using a fluidized bed type coating device, the resin layer coating liquid was applied to the surface of 7,200 parts by mass of a spherical manganesemagnesium ferrites with an average particle size of 70 pm to produce a carrier.

[0208] (Production of developer)Using a ball mill, 7 parts by mass of each of the toners 1 to 8 and 93 parts by mass of the carrier were mixed to produce a developer. An image was formed as follows on a transfer sheet using each of the developers thus produced.

[0209] (Example 1)A color image was output as follows. A production printer, Ricoh Pro C7200S, manufactured by Ricoh Co., Ltd. was used to output the color image. This apparatus includes a fifth station for placing a special color toner and stations for process colors.The toner 1 and its developer were installed in the fifth station for placing a special color toner.The toner 2 and its developer were installed in a black station.The toner 3 and its developer were installed in a cyan station.The toner 4 and its developer were installed in a magenta station.The toner 5 and its developer were installed in a yellow station.

[0210] FIG. 6 illustrates an output color image, which is a design of the Ricoh logo and the New Zealand national flag. The reason for using this national flag is that it is considered suitable for color evaluation.Using the above-mentioned apparatus, a mirror image in which the design presented in FIG. 6 was inverted left to right was output on a transfer sheet (FORCE-IN PAPER A3 sheet manufactured by QuickArt Online Shop). When outputting the image, an image in which each color of FIG. 6 is separately expressed was output on the transfer sheet. That is, the toner layer was a single layer. A white part of the national flag is an image expressed with the white toner. In this manner, a thermal transfer print sheet 1 was produced.The standard deposition amount of each toner on the transfer sheet was set to 26 mg / cm2, and the toner layer thickness was set to 15 pm. Due to the large toner particle size, such standard deposition amount and toner layer thickness could be achieved.

[0211] Table 1 presents the transmittance for all visible light wavelengths when a solid image with a deposition thickness of 30 pm was formed on the transfer sheet using the toner 1. In Table 1, the term “<1” indicates that the transmittance is less than 1%. The transmittance of the present disclosure refers to the maximum transmittance within the visible light wavelength range (380 to 780 nm).The transmittance of a 30 pm thick solid image produced on an OHP substrate was measured with ultraviolet / visible / near infrared spectrophotometer (UV-3600 manufactured by Shimadzu Corp.) using a film holder under the following conditions.•Wavelength range: 380 nm to 780 nmScan speed: Medium• Sampling pitch: 0.5 nmSlit width: 5.0 nm

[0212] (Example 2)Image formation was performed under the same conditions as for the thermal transfer print sheet of Example 1 to produce a thermal transfer print sheet 2 in which the standard deposition amount of each toner was 52 mg / cm2, and the toner layer thickness was 30 pm.

[0213] (Example 3)In the production of the thermal transfer print sheet of Example 1, the output thermal transfer print sheet was returned to the paper stocker to print the same design again. Such an operation was repeated four times for image formation to produce a thermal transfer print sheet 3 in which the standard deposition amount of each toner was 104 mg / cm2, and the toner layer thickness was 60 pm.

[0214] (Comparative example 1)Using the same apparatus and the same transfer sheet as in Example 1, the same evaluation image (FIG. 6) as in Example 1 was output.In Comparative example 1, RICOH Pro Toner White C7100 (genuine white toner) was installed in the fifth station for placing a special color, and RICOH Pro Toner C7200 series (genuine color toner) was installed in each process color station. The white part of the national flag is an image expressed with the genuine white toner.The standard deposition amount of each color toner was set to 0.45 mg / cm2, and the standard deposition amount of the white toner was set to 1.70 mg / cm2. In this manner, a thermal transfer print sheet 4 having an image with a toner layer thickness of 10 pm was produced.

[0215] The RICOH Pro Toner C7200 series (genuine color toner) is a toner that includes a polyester, a thermoplastic elastomer (polyurethane elastomer), and wax.Further, the RICOH Pro Toner White C7100 (genuine white toner) does not include a thermoplastic elastomer (polyurethane elastomer).The genuine color toner had a transmittance of 20% for the cyan toner, 70% for the magenta toner, and 80% for the yellow toner, measured for all visible light wavelengths using a solid image with a deposition thickness of 30 pm.The genuine white toner had a transmittance of less than 1% measured for all visible light wavelengths using a solid image with a deposition thickness of 30 pm.

[0216] (Comparative example 2)In Comparative example 1, after forming the image of FIG. 6 on the transfer sheet, a masked image was printed by overcoating the image with the genuine white toner to produce a thermal transfer print sheet 5 having an image with a white toner layer thickness of 20 pm.

[0217] (Comparative example 3)In Comparative example 2, after masking the image with the genuine white toner, printing was further repeated to form a layer of the genuine white toner with a toner layer thickness of 35 pm, thereby producing a thermal transfer print sheet 6.

[0218] (Comparative example 4)In Comparative example 4, the toners were installed as follows.The toner 1 and its developer were installed in the fifth station for placing a special color toner.The toner 2 and its developer were installed in a black station.The toner 6 and its developer were installed in a cyan station.The toner 7 and its developer were installed in a magenta station.The toner 8 and its developer were installed in a yellow station.Apart from the above-mentioned changes, a thermal transfer print sheet 7 was produced in the same manner as in Example 1.

[0219] (Comparative example 5)A thermal transfer print sheet 8 was produced in the same manner as in Example 2, except that the toners were installed in the same manner as in Comparative example 4.

[0220] (Comparative example 6)A thermal transfer print sheet 9 was produced in the same manner as in Example 3, except that toners were installed in the same manner as in Comparative example 4.

[0221] (Evaluation)The images were formed on the transfer objects as described below to be evaluated. The results are presented in Table 2.

[0222] <Image formation on transfer object (white T-shirt)>Using the thermal transfer print sheet produced above, an image was formed on a white T- shirt (manufactured by United Athle, 5.6 oz., high quality T-shirt, low bleed) as a transfer object as follows.The thermal transfer print sheet was placed on the T-shirt and set in a heat press machine (Model HT P234PS1 manufactured by Piotec Co., Ltd) to perform heating and pressing at a temperature of 130°C and a pressure of 300g / cm2for 20 seconds. The transfer sheet was then peeled off, thereby thermally transferring the image on the thermal transfer print sheet to the T-shirt.Next, a release paper was placed on the image transferred to the T-shirt, and the T-shirt was heated and pressed again at a temperature of 130°C and a pressure of 300g / cm2for 20 seconds. After that, the release paper was peeled off to complete a printed T-shirt.

[0223] <Image formation on transfer object (black T-shirt)>A printed T-shirt was produced in the same manner as in the above-mentioned image formation on the white T-shirt, except that a black T-shirt (manufactured by United Athle, 4.7 oz., dry silky touch T-shirt, low bleed) was used as the transfer object instead of the white T- shirt.

[0224] <Evaluation of fixation>The fixation of the two types of the printed T-shirts obtained in Examples and Comparative Examples was evaluated according to the following evaluation criteria. Fixation was evaluated by visually examining the printed T-shirts for color loss, peeling, and image cracking.

[0225] [Evaluation criteria]Good: No color loss, peeling, or cracking on printed T-shirtPoor: Some color loss, peeling, or cracking on printed T-shirt

[0226] In Examples 1 to 3 and Comparative examples 1 and 2, there were no problems with the fixation of both types of the printed T-shirts. On the other hand, in Comparative example 3, peeling or cracking occurred in the white part. In Comparative examples 4 to 6, some parts of the gray letters showed color loss.

[0227] <Evaluation of washing fastness>The washing fastness (which may also be referred to as washing and drying durability) was evaluated as follows.The two types of the printed T-shirts obtained in each of Examples and Comparative examples were washed and dehydrated using a vertical fully automatic washing machine (AW-425M manufactured by Toshiba Corp.) and a neutral detergent (SUPER NANOX manufactured by Lion Corp.). The printed T-shirts were then placed in a dryer (NH-D402P manufactured by Panasonic Corp.) for automatic drying. This cycle was repeated 5 times. Evaluation was performed according to the following evaluation criteria. “Excellent” and “Good” are acceptable, and “Poor” is unacceptable.

[0228] [Evaluation criteria]Excellent: No deterioration of image even after 5 wash and dry cyclesGood: Some image cracking and cracking but no peeling after 5 wash and dry cyclesPoor: Additionally, some peeling after 5 wash and dry cycles

[0229] Example 1 had some cracking, but no peeling. Examples 2 and 3 and Comparative examples 5 and 6 showed no deterioration and were excellent. Comparative examples 1 and 4 had some cracking, but no peeling. Comparative examples 2 and 3 showed peeling or cracking in the white part.Note that, in garment printing in which an image is formed using the thermal transfer sheet according to an embodiment of the present invention, no color fading occurred, and all deterioration resulted from damage to the image, such as cracking or peeling.

[0230] <Evaluation of color image reproducibility>By comparing the white T-shirt image with the black T-shirt image obtained above, the reproducibility of color image caused by a difference in brightness of the transfer object was evaluated.The evaluation was performed as follows.A saturation of the red part of the white T-shirt image is defined as “a”, and the saturation of the blue part of the white T-shirt image is defined as “b”. A saturation of the red part of the black T-shirt image is defined as “c”, and a saturation of the blue part of the black T-shirt image is defined as “d”. The difference in saturation of the red part (a-c) and the difference in saturation of the blue part (b-d) are each evaluated. The evaluation criteria are as follows, with “Excellent” and “Good” being acceptable. In the cases of “Excellent” and “Good”, it can be concluded that the image on the white T-shirt can be reproduced on the black T-shirt.

[0231] [Evaluation criteria]Excellent: The difference in saturation of the red part and the difference in saturation of the blue part are both less than 3.Good: The difference in saturation of the red part and the difference in saturation of the blue part are both less than 5, and at least one of the differences in saturation of the red part and the blue part is 3 or more and less than 5.Poor: The difference in saturation of the red part and the difference in saturation of the blue part are both 5 or more.

[0232] In Example 1, the difference in saturation of the red part was 3 or more and less than 5. In Examples 2 and 3, the difference in saturation of the red part and the difference in saturation of the blue part were both less than 3. In Comparative examples 1, 2, and 4 to 6, the difference in saturation of the red part and the difference in saturation of the blue part were both 5 or more. In Comparative example 3, the difference in saturation of the red part and the difference in saturation of the blue part were both 3 or more and less than 5.

[0233] <Total evaluation>In the above-mentioned evaluation, the product that did not have any “Poor” evaluation was considered acceptable. Examples 1 to 3 were acceptable, while Comparative examples 1 to 6 resulted in “Poor” in some evaluation and therefore were not acceptable.

[0234] [Table 1]

[0236] Aspects of the present invention are, for example, as follows.< Aspect 1>A toner including: a polyester; a polyurethane elastomer; a wax; and one of a white pigment and a black pigment, wherein the toner has a transmittance of less than 5% for all visible light wavelengths when formed into a solid image with a deposition thickness of 30 pm on an OHP substrate. <Aspect 2>The toner according to the <Aspect 1>, further including a colorant other than the one of the white pigment and the black pigment.< Aspect 3>A toner set including: a toner (A) including a white pigment, a polyester, a polyurethane elastomer, and a wax; a toner (B) including a black pigment, a polyester, a polyurethane elastomer, and a wax; and a toner (C) including at least one of a white pigment and a black pigment, a colorant other than the at least one of the white pigment and the black pigment, a polyester, a polyurethane elastomer, and a wax, wherein all of toners each have a transmittance of less than 5% for all visible light wavelengths when formed into a solid image having a deposition thickness of 30 pm on an OHP substrate.<Aspect 4>The toner set according to the <Aspect 3> in which the toner (C) includes the white pigment and the black pigment.< Aspect 5>An image forming method including: forming an electrostatic latent image on an electrostatic latent image bearer; developing the electrostatic latent image with the toner according to the <Aspect 1> or < Aspect 2> or the toner set according to < Aspect 3> or < Aspect 4> to form a toner image; transferring the toner image to a transfer sheet; and fixing the toner image to the transfer sheet to produce a thermal transfer print sheet. <Aspect 6>The image forming method according to the <Aspect 5>, in which the toner image on the thermal transfer print sheet is a single-layer toner image that does not overlap with any other toner image.<Aspect 7>The image forming method according to the <Aspect 5> or <Aspect 6>, further including: bringing the thermal transfer print sheet into contact with a transfer object and applying heat and pressure thereto to thermally transfer the toner image on the thermal transfer print sheet to the transfer obj ect.<Aspect 8>The image forming method according to the <Aspect 7>, in which the transfer object is a fabric.<Aspect 9>The image forming method according to the <Aspect 8>, in which the fabric comprises a cotton, polyester, nylon, rayon, or silk fiber, or a mixture of these fibers.< Aspect 10>An image forming apparatus including: the toner according to the < Aspect 1> or < Aspect 2> or the toner set according to the < Aspect 3> or < Aspect 4>: an electrostatic latent image bearer; an electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image bearer; a developing means for developing the electrostatic latent image with the toner or the toner set to form a toner image; a transfer means for transferring the toner image to the transfer sheet; and a fixing means for fixing the toner image to the transfer sheet to produce a thermal transfer print sheet.< Aspect 11>A process cartridge including detachably attachable to an image forming apparatus including a fixing means, including: the toner according to the < Aspect 1> or < Aspect 2>; an electrostatic latent image bearer; an electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image bearer; a developing means for developing the electrostatic latent image with the toner to form a toner image; and a transfer means for transferring the toner image to a transfer sheet, wherein, when the process cartridge is attached to the image forming apparatus, the fixing means fixes the toner image to the transfer sheet to produce a thermal transfer print sheet.

[0237] The above-described embodiments are illustrative and do not limit the present invention. Thus, numerous additional modifications and variations are possible in light of the above teachings. For example, elements and / or features of different illustrative embodiments may becombined with each other and / or substituted for each other within the scope of the present invention. Any one of the above-described operations may be performed in various other ways, for example, in an order different from the one described above.

[0238] This patent application is based on and claims priority to Japanese Patent Application No. 2024-043724, filed on March 19, 2024, in the Japan Patent Office, the entire disclosure of which is hereby incorporated by reference herein.[Reference Signs List]

[0239] 10 Photoconductor drum18 Image forming means20 Charging roller30 Exposure device40 Developing device41 Developing belt45 Developing unit50 Intermediate transfer object60 Cleaning device70 Discharging lamp

Claims

[CLAIMS]

1. A toner comprising: a polyester; a polyurethane elastomer; a wax; and one of a white pigment and a black pigment, wherein the toner has a transmittance of less than 5% for all visible light wavelengths when formed into a solid image with a deposition thickness of 30 pm on an OHP substrate.

2. The toner according to claim 1, further comprising a colorant other than the one of the white pigment and the black pigment.

3. A toner set comprising: a toner (A) including a white pigment, a polyester, a polyurethane elastomer, and a wax; a toner (B) including a black pigment, a polyester, a polyurethane elastomer, and a wax; and a toner (C) including at least one of a white pigment and a black pigment, a colorant other than the at least one of the white pigment and the black pigment, a polyester, a polyurethane elastomer, and a wax, wherein all of toners each have a transmittance of less than 5% for all visible light wavelengths when formed into a solid image having a deposition thickness of 30 pm on an OHP substrate.

4. The toner set according to claim 3, wherein the toner (C) includes both the white pigment and the black pigment.

5. An image forming method comprising: forming an electrostatic latent image on an electrostatic latent image bearer; developing the electrostatic latent image with the toner according to claim 1 or 2 or the toner set according to claim 3 or 4 to form a toner image; transferring the toner image to a transfer sheet; and fixing the toner image to the transfer sheet to produce a thermal transfer print sheet.

6. The image forming method according to claim 5, wherein the toner image on the thermal transfer print sheet is a single-layer toner image that does not overlap with any other toner image.

7. The image forming method according to claim 5 or 6, further comprising: bringing the thermal transfer print sheet into contact with a transfer object and applying heat and pressure thereto to thermally transfer the toner image on the thermal transfer print sheet to the transfer obj ect.

8. The image forming method according to claim 7, wherein the transfer object is a fabric.

9. The image forming method according to claim 8, wherein the fabric comprises a cotton, polyester, nylon, rayon, or silk fiber, or a mixture of these fibers.

10. An image forming apparatus comprising: the toner according to claim 1 or 2 or the toner set according to claim 3 or 4; an electrostatic latent image bearer; an electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image bearer; a developing means for developing the electrostatic latent image with the toner or the toner set to form a toner image; a transfer means for transferring the toner image to a transfer sheet; and a fixing means for fixing the toner image to the transfer sheet to produce a thermal transfer print sheet.

11. A process cartridge detachably attachable to an image forming apparatus including a fixing means, the process cartridge comprising: the toner according to claim 1 or 2; an electrostatic latent image bearer; an electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image bearer; a developing means for developing the electrostatic latent image with the toner to form a toner image; and a transfer means for transferring the toner image to a transfer sheet, wherein, when the process cartridge is attached to the image forming apparatus, the fixing means fixes the toner image to the transfer sheet to produce a thermal transfer print sheet.

Images