Toner and method for producing toner

Abstract

The present invention relates to a toner and a method for producing a toner. A toner including toner particles containing a binder resin and boric acid, wherein the toner has an average circularity of 0.95 or more, and the toner has a shape factor SF1 of 105 to 125, and a method for producing a toner having excellent durability, thereby having the above-mentioned physical properties and improving transfer efficiency.

Description

Technical Field

[0001] This disclosure relates to a toner suitable for image forming methods such as electrophotography, electrostatic recording, and toner spraying, as well as a method for manufacturing the toner. Background Technology

[0002] In recent years, printers and copiers have achieved high levels of image quality and durability. At the same time, especially for printers, miniaturization and waste-free operation have become widely required.

[0003] Printers must be adaptable to various business scenarios, such as network printers used by a large number of people via a network and personal printers used in SOHO environments. Furthermore, in office or SOHO environments, there is a strong desire to eliminate maintenance associated with waste such as waste toner replacements. Therefore, there remains a strong demand for space-saving printers—that is, printers that are miniaturized and operate without waste.

[0004] Miniaturization of the fuser unit and processing cartridge is primarily effective for printer miniaturization. In particular, the processing cartridge occupies a large portion of the printer's volume, and miniaturizing the processing cartridge greatly contributes to printer miniaturization.

[0005] Miniaturization of the developing and cleaning units is effective for printer miniaturization. Regarding the miniaturization of the developing unit, there are two-component and one-component electrophotographic developing systems, but the one-component developing system is more suitable for miniaturization. This is because it does not use components such as carriers.

[0006] Regarding cleaning devices, cleaner-free systems, which completely lack cleaning components, are extremely suitable for miniaturizing the processing cartridge. In many printers, toner residue on the electrostatic latent image carrier (photosensitive element) left after the transfer step (transfer residue toner) is scraped off by a cleaning blade or similar device and collected in a cleaning container, becoming waste toner. In cleaner-free systems, however, there is no cleaning blade or cleaning container; the transfer residue toner is collected again in the developing unit and aids in development. Therefore, the size of the processing cartridge can be significantly reduced, no waste toner is generated, and it makes a significant contribution to the transition to waste-free operation.

[0007] In this context, toners with minimal transfer residue are crucial, regardless of the presence or absence of cleaning devices. Typically, methods to obtain toners with low transfer residue include, for example, spheroidizing toner particles to reduce adhesion to the photosensitive element. However, since spheroidization also reduces the adhesion between toner particles, transfer dust is likely to occur. To address this issue, Japanese Patent Application Publication No. 2007-241310 proposes a toner that simultaneously improves transfer rate and reduces transfer dust by controlling the surface shape of the toner. Summary of the Invention

[0008] While toners that simultaneously improve transfer rate and reduce transfer dust can be obtained according to Japanese Patent Application Publication No. 2007-241310, this is not sufficient for printers that require long lifespans in recent years. Furthermore, toners with irregular shapes, such as those proposed in Japanese Patent Application Publication No. 2007-241310, are prone to localized excessive force when rubbed against the squeegee or roller during development, and their durability is not considered adequate.

[0009] The problem to be solved by this disclosure is to provide a toner with excellent durability, which can achieve at a high level of improved transfer rate and reduced transfer dust that contribute to the miniaturization of printers and the transition to waste-free operation, and these transfer properties are maintained over a long period of time, and a method for manufacturing the toner is also provided.

[0010] This disclosure relates to a toner comprising toner particles containing a binder resin and boric acid, characterized in that,

[0011] The toner has an average roundness of 0.95 or higher, and

[0012] The shape factor SF1 of the toner is 105 to 125.

[0013] This disclosure also relates to a method for manufacturing a toner, characterized in that,

[0014] The method for manufacturing the toner comprises the following steps (1) to (3) in the following order:

[0015] (1) The dispersion step of preparing a dispersion of adhesive resin particles containing the adhesive resin.

[0016] (2) The aggregation step of agglomerating the binder resin particles contained in the binder resin particle dispersion to form aggregates, and

[0017] (3) The fusion step of heating and fusing the aggregate, and

[0018] A boric acid source is added in at least one of the aggregation step and the fusion step.

[0019] This disclosure provides a toner with excellent durability, which achieves a high level of improvement in transfer rate and reduction in transfer dust, and these transfer properties are maintained over a long period of time.

[0020] Further features of the invention will become apparent from the following description of exemplary embodiments. Detailed Implementation

[0021] In this disclosure, the expressions “from XX to YY” or “XX to YY” indicating a range of values ​​refer to a range of values ​​that includes a lower limit and an upper limit as endpoints, unless otherwise stated. Furthermore, when a range of values ​​is described in a stepwise manner, the upper and lower limits of each range of values ​​may be appropriately combined.

[0022] In this disclosure, "(meth)acrylic acid" means "acrylic acid" and / or "methacrylic acid".

[0023] The toners disclosed herein will be described in more detail below.

[0024] As a result of efforts to address the aforementioned problems of the prior art, the inventors have discovered that these problems can be solved by a toner comprising toner particles containing a binder resin, wherein the toner is controlled into a specific shape, and the toner particles comprise boric acid.

[0025] This disclosure relates to a toner comprising toner particles containing a binder resin and boric acid, characterized in that,

[0026] The toner has an average roundness of 0.95 or higher, and

[0027] The shape factor SF1 of the toner is 105 to 125.

[0028] First, by setting the average roundness of the toner to 0.95 or higher and the shape factor SF1 to 105 to 125, a toner with a high transfer rate can be obtained. On the other hand, toners with shapes within the above range generate transfer dust. However, the presence of boric acid in toner particles with shapes within the above range allows for a high level of improvement in transfer rate and a reduction in transfer dust. This is likely because boron derived from boric acid has a metallic property, thus enabling appropriate charge transfer between or within toner particles, suppressing electrostatic repulsion between developed toner particles, and allowing transfer to occur in an aggregated state.

[0029] To obtain the desired toner shape, it is preferable to use a chemical toner manufacturing method to obtain toner particles in an aqueous medium, such as emulsion aggregation or suspension polymerization. Specifically, the toner shape can be obtained through spheroidizing, cooling, and annealing steps in the manufacturing process.

[0030] Examples of spheroidizing steps include heat treatment steps performed at temperatures above 90°C, preferably above 92°C, and preferably below 95°C.

[0031] Examples of cooling steps include cooling treatment performed at a cooling rate of 0.1°C / second or higher, preferably 0.5°C / second or higher, more preferably 2°C / second or higher, and even more preferably 4°C / second or higher.

[0032] The annealing step is exemplified as a heat treatment step, wherein heat treatment is performed for 5 hours at a temperature at which the glass transition temperature (Tg) of the toner is maximum. The toner shape of this disclosure can be readily achieved through these steps performed under appropriate conditions. In particular, to obtain a shape factor SF1 of 105 to 125 for the toner cross-section formed by the section polishing method (CP section method), and a contact area ratio (D / S) of 14% or less for the toner, it is preferable to undergo a cooling step and an annealing step. By undergoing these steps, the formation of indentations on the toner surface can be suppressed, and the shape factor SF1 of the cross-section can be easily reduced to below 125 and the contact area ratio (D / S) to below 14%.

[0033] The average roundness of the toner is 0.95 or higher, preferably 0.97 or higher, and more preferably 0.98 or higher. Furthermore, the average roundness is preferably 0.99 or lower. The shape factor SF1 of the toner is 105 to 125, preferably 108 to 120.

[0034] When the average roundness and shape factor SF1 of the toner are within the above range, the shape of the toner is close to a true sphere, thereby suppressing the adhesion of the toner to the photosensitive component and improving the transfer rate.

[0035] The shape factor SF1 of the toner cross-section formed by the cross-section polishing method (CP cross-section method) is preferably 105 to 125, more preferably 108 to 120. The shape factor SF1 of the cross-section can be controlled by changing the manufacturing conditions described above. When the shape factor SF1 of the cross-section is within the above range, the toner surface has few irregularities, and localized external forces are unlikely to be applied to the peaks and valleys, thereby greatly improving the durability of the toner and maintaining transfer performance such as improved transfer rate and reduced transfer dust over a long period of time.

[0036] When the toner is sieved through a 22-μm opening sieve for 10 seconds while falling from a height of 10 cm onto a horizontal glass plate, and the total contact area between 50 toners and the glass plate is defined as the contact area D, and the total projected area of ​​the 50 toners is defined as S, the contact area ratio (D / S) is preferably 3 to 14%, more preferably 5 to 8%. The contact area ratio (D / S) can be controlled by changing the above manufacturing conditions. When the contact area ratio (D / S) is within the above range, the toner surface has few irregularities, and localized external forces are unlikely to be applied to the protrusions and depressions, thereby greatly improving the toner durability and maintaining transfer performance such as improved transfer rate and reduced transfer dust over a long period.

[0037] Preferably, the toner further comprises an external additive, said external additive being silica microparticles, wherein the coverage of the toner particles by the silica microparticles, as measured by X-ray photoelectron spectroscopy, is 50 to 80% of the area, more preferably 60 to 70% of the area. When the coverage is within the above range, the local charge difference generated between the covered and uncovered portions is suppressed, thereby further reducing transfer dust and improving transferability. The coverage of the silica microparticles can be controlled by adjusting the amount of silica microparticles added, the external addition time, etc.

[0038] The dispersion evaluation index of silica particles on the surface of the toner is preferably from 0.10 to 2.00, more preferably from 0.20 to 0.40. By setting it to the above range, the portions covered by external additives and the uncovered portions are suppressed, thus further reducing transfer dust and improving transferability. The dispersion evaluation index can be controlled by adjusting the amount of silica particles added, the external addition time, etc.

[0039] Boric acid was preferably detected in the IR analysis of toner particles using the ATR method with germanium as the ATR crystal. This means that boric acid is present near the toner surface. When boric acid is present near the toner surface, appropriate charge transfer occurs between or within the toner particles, suppressing electrostatic repulsion between the developed toner particles and promoting transfer in an aggregated state. Therefore, transfer dust can be reduced and durability can be improved.

[0040] In the fluorescence X-ray measurement of toner particles, the boron intensity is preferably 0.1 to 0.6 kcps, more preferably 0.2 to 0.6 kcps. When the boron intensity is within the above range, the toner particles contain an appropriate amount of boric acid, and an appropriate amount of charge transfers between or within the toner particles, suppressing electrostatic repulsion between the developed toner particles and enabling transfer in an aggregated state. Therefore, transfer dust can be reduced and durability can be improved.

[0041] Boric acid can be incorporated into toner particles by using a boric acid source as an internal additive or flocculant. In particular, by adding a boric acid source as a flocculant, boric acid can be introduced into the vicinity of the toner particle surface.

[0042] The components that make up the toner and the manufacturing method of the toner will be described in more detail below.

[0043] Adhesive resin

[0044] The colorant granules contain a binder resin. The amount of binder resin is preferably 50% by mass or more relative to the total amount of resin components in the colorant granules.

[0045] There are no particular limitations on the binder resin, examples of which include styrene-acrylic resins, epoxy resins, polyester resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, and their mixed and composite resins. Styrene-acrylic resins and polyester resins are preferred because they are inexpensive, readily available, and can achieve excellent low-temperature fixing properties.

[0046] Polyester resins can be synthesized by selecting and combining appropriate components from polycarboxylic acids, polyols, hydroxycarboxylic acids, etc., using conventionally known methods such as transesterification and polycondensation.

[0047] Polycarboxylic acids are compounds containing two or more carboxyl groups per molecule. Preferably, dicarboxylic acids are used, which are compounds containing two carboxyl groups per molecule.

[0048] Examples of dicarboxylic acids include oxalic acid, succinic acid, glutaric acid, maleic acid, adipic acid, β-methyl adipic acid, azelaic acid, sebacic acid, nonanedicarboxylic acid, decanedicarboxylic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, fumaric acid, citralic acid, diethylene glycol, cyclohexane-3,5-diene-1,2-carboxylic acid, hexahydroterephthalic acid, malonic acid, pimecrolic acid, octanoic acid, phthalic acid, isophthalic acid, terephthalic acid, tetrachlorophthalic acid, chlorophthalic acid, nitrophthalic acid, p-carboxyphenylacetic acid, terephthalic acid, isophthalic acid, phthalic acid, diphenylacetic acid, diphenyl-p,p'-dicarboxylic acid, naphthalene-1,4-dicarboxylic acid, naphthalene-1,5-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, anthracenedicarboxylic acid, cyclohexanedicarboxylic acid, etc.

[0049] Examples of polycarboxylic acids other than dicarboxylic acids include trimellitic acid, pyromellitic acid, pyromellitic tetracarboxylic acid, naphthalenetricarboxylic acid, pyrenetricarboxylic acid, pyrenetetracarboxylic acid, itaconic acid, pentenic acid, n-dodecylsuccinic acid, n-dodecenylsuccinic acid, isododecylsuccinic acid, isododecenylsuccinic acid, n-octylsuccinic acid, n-octenylsuccinic acid, etc. These can be used alone or in combination of two or more.

[0050] Polyols are compounds containing two or more hydroxyl groups per molecule. Diols, which are compounds containing two hydroxyl groups per molecule, are preferred.

[0051] Specific examples include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, and 1,14-eicosodecanol. Diols (1,14-eicosanedecanediol), diethylene glycol, triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, 1,4-cyclohexanediol, 1,4-cyclohexanediol, 1,4-butenediol, neopentyl glycol, 1,4-cyclohexanediol, polybutanediol, hydrogenated bisphenol A, bisphenol A, bisphenol F, bisphenol S, and olefin oxide adducts (ethylene oxide, propylene oxide, butane oxide, etc.) of the above bisphenols.

[0052] Preferably, alkylene glycols with 2 to 12 carbon atoms and alkylene oxide adducts of bisphenols are used, and particularly preferred are alkylene oxide adducts of bisphenols and their combinations with alkylene glycols with 2 to 12 carbon atoms.

[0053] Examples of polyols with three or more components include glycerol, trimethylolethane, trimethylolpropane, pentaerythritol, hexamethylolmelamine, hexaethylolmelamine, tetramethylolbenzoguanamine, tetraethylolbenzoguanamine, sorbitol, triphenol (PA), phenolic varnish, cresol varnish, and olefinic adducts of the above-mentioned polyphenols with three or more components. These can be used alone or in combination of two or more.

[0054] Examples of styrene-acrylic resins include homopolymers composed of the following polymerizable monomers, copolymers obtained by combining two or more of these, or mixtures thereof.

[0055] Styrene monomers, such as styrene, α-methylstyrene, β-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, p-n-butylstyrene, p-tert-butylstyrene, p-n-hexylstyrene, p-n-octylstyrene, p-n-nonylstyrene, p-n-decylstyrene, p-n-dodecylstyrene, p-methoxystyrene, and p-phenylstyrene;

[0056] (Meth)acrylate monomers, such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, n-pentyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, n-nonyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, dimethyl phosphate, ethyl methacrylate, diethyl phosphate, dibutyl phosphate, ethyl methacrylate, and 2-benzoyloxyethyl methacrylate, (meth)acrylonitrile, 2-hydroxyethyl methacrylate, (meth)acrylic acid, and maleic acid;

[0057] Vinyl ether monomers, such as vinyl methyl ether and vinyl isobutyl ether;

[0058] Vinyl ketone monomers, such as vinyl methyl ketone, vinyl ethyl ketone, vinyl isopropenyl ketone, etc.; and

[0059] Polyolefins, such as ethylene, propylene, butadiene, etc.

[0060] Styrene-based acrylic resins can utilize multifunctional polymerizable monomers as needed. Examples of multifunctional polymerizable monomers include diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 2,2'-bis(4-((meth)acryloyloxydiethoxy)phenyl)propane, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, divinylbenzene, divinylnaphthalene, divinyl ether, etc.

[0061] In addition, known chain transfer agents and known polymerization inhibitors can be added to control the degree of polymerization.

[0062] Examples of polymerization initiators used to obtain styrene-acrylic resins include organic peroxide initiators and azo polymerization initiators.

[0063] Examples of organic peroxide initiators include benzoyl peroxide, lauroyl peroxide, di-α-cumyl peroxide, 2,5-dimethyl-2,5-bis(benzoyl peroxide)hexane, bis(4-tert-butylcyclohexyl)peroxydicarbonate, 1,1-bis(tert-butylperoxy)cyclododecane, tert-butylperoxymaleic acid, bis(tert-butylperoxy)isophthalate, methyl ethyl ketone peroxide, tert-butylperoxy-2-ethylhexanoate, diisopropylperoxycarbonate, cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide, and tert-butyl perpentanoate.

[0064] Examples of azo polymerization initiators include 2,2'-azobis-(2,4-dimethylpentanonitrile), 2,2'-azobisisobutyronitrile, 1,1'-azobis(cyclohexane-1-carboxynitrile), 2,2'-azobis-4-methoxy-2,4-dimethylpentanonitrile, azobismethylbutyronitrile, and 2,2'-azobis-(methyl isobutyrate).

[0065] Alternatively, redox initiators that combine oxidizing and reducing substances can also be used as polymerization initiators.

[0066] Examples of oxidizing substances include hydrogen peroxide, inorganic peroxides of persulfates (sodium, potassium, and ammonium salts), and oxidizing metal salts of tetravalent cerium.

[0067] Examples of reducing substances include reducing metal salts (ferrous, copper, and chromium salts), ammonia, lower amines (amines with 1 to 6 carbon atoms, such as methylamine and ethylamine), amine compounds such as hydroxylamine, reducing sulfur compounds such as sodium thiosulfate, sodium dithionite, sodium bisulfite, sodium sulfite, sodium formaldehyde sulfoxylate, lower alcohols (with 1 to 6 carbon atoms), ascorbic acid or its salts, and lower aldehydes (with 1 to 6 carbon atoms).

[0068] The polymerization initiator is selected based on the 10-hour half-life temperature and can be used alone or in combination. The amount of polymerization initiator added varies depending on the desired degree of polymerization, but is typically 0.5 to 20.0 parts by weight relative to 100.0 parts by weight of polymerizable monomer.

[0069] Release agent

[0070] It is known that wax can be used as a release agent for toners.

[0071] Specific examples include petroleum waxes and their derivatives, such as solid paraffin wax, microcrystalline wax, and petrolatum; lignite waxes and their derivatives; hydrocarbon waxes and their derivatives obtained by the Fischer-Tropsch process; polyolefin waxes and their derivatives, such as polyethylene; and natural waxes and their derivatives, such as carnauba wax and candelilla wax. The derivatives include oxides, block copolymers with vinyl monomers, and grafted modified products.

[0072] Other examples include alcohols such as higher fatty alcohols, fatty acids such as stearic acid, palmitic acid, etc., or their amides, esters, and ketones, hardened castor oil and its derivatives, vegetable waxes, and animal waxes. These can be used alone or in combination.

[0073] Polyolefins, hydrocarbon waxes produced via the Fischer-Tropsch process, or petroleum-based waxes are preferred because they tend to improve developing and transfer properties. Antioxidants can be added to these waxes without affecting the properties of the toner.

[0074] Furthermore, from the viewpoint of phase separation or crystallization temperature relative to the binder resin, higher fatty acid esters such as betaine acid betaine ester and sebacic acid dibetaine ester are preferred examples.

[0075] The amount of release agent is preferably 1.0 to 30.0 parts by weight relative to 100.0 parts by weight of adhesive resin.

[0076] The melting point of the release agent is preferably 30 to 120°C, more preferably 60 to 100°C. By using a release agent with a melting point of 30 to 120°C, the release effect is effectively achieved, and a wider fixing area is ensured.

[0077] plasticizer

[0078] Crystalline plasticizers are preferably used in the colorants of this invention to improve rapid melting. There are no particular limitations on the plasticizer; known plasticizers suitable for colorants as described below can be used.

[0079] Esters of monohydric alcohols and aliphatic carboxylic acids, such as betaine, stearate, and palmitate, or esters of monohydric carboxylic acids and aliphatic alcohols; esters of dihydric alcohols and aliphatic carboxylic acids, such as ethylene glycol distearate, di-betaine sebacate, and hexanediol di-betaine, or esters of dihydric carboxylic acids and aliphatic alcohols; esters of trihydric alcohols and aliphatic carboxylic acids, such as glyceryl tri-betaine, or esters of trihydric carboxylic acids and fatty alcohols; esters of tetrahydric alcohols and aliphatic carboxylic acids. Esters of aliphatic carboxylic acids, such as pentaerythritol tetrastearate and pentaerythritol tetrapalmitate, or esters of tetracarboxylic acids and aliphatic alcohols; esters of hexahydrols and aliphatic carboxylic acids, such as dipentaerythritol hexastearate and dipentaerythritol hexapalmitate, or esters of hexahydric acids and aliphatic alcohols; esters of polyols and aliphatic carboxylic acids, such as polyglycerol betaine, or esters of polycarboxylic acids and aliphatic alcohols; and natural ester waxes, such as carnauba wax and rice wax. These can be used alone or in combination.

[0080] Colorant

[0081] Toner particles may include colorants. Known pigments and dyes can be used as colorants. From the viewpoint of excellent weather resistance, pigments are preferred as colorants.

[0082] Examples of cyan colorants include copper phthalocyanine compounds and their derivatives, anthraquinone compounds, and basic dye lake compounds.

[0083] Specific examples include CI Pigment Blue 1, 7, 15, 15:1, 15:2, 15:3, 15:4, 60, 62, and 66.

[0084] Examples of magenta colorants include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinone compounds, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindole compounds, perylene compounds, etc.

[0085] Specific examples include CI Pigment Red 2, 3, 5, 6, 7, 23, 48:2, 48:3, 48:4, 57:1, 81:1, 122, 144, 146, 150, 166, 169, 177, 184, 185, 202, 206, 220, 221 and 254, and CI Pigment Violet 19.

[0086] Examples of yellow colorants include condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and allylamide compounds.

[0087] Specific examples include CI Pigment Yellow 12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 97, 109, 110, 111, 120, 127, 128, 129, 147, 151, 154, 155, 168, 174, 175, 176, 180, 181, 185, 191, and 194.

[0088] Examples of black colorants include those that use the aforementioned yellow, magenta, and cyan colorants to achieve a black color, as well as carbon black.

[0089] These colorants can be used alone or as a mixture, and they can be used in the form of solid solutions.

[0090] The colorant is preferably used in an amount of 1.0 to 20.0 parts by weight relative to 100.0 parts by weight of the adhesive resin.

[0091] Charge control agents and charge control resins

[0092] Toner particles may include charge control agents or charge control resins.

[0093] As charge control agents, those known to the public can be used, with those exhibiting rapid triboelectric charging speed and the ability to stably maintain a certain amount of triboelectric charge being particularly preferred. Furthermore, when manufacturing toner particles via suspension polymerization, charge control agents with low polymerization inhibition and which substantially do not provide soluble materials in aqueous media are particularly preferred.

[0094] Examples of toners that are negatively charged charge control agents include monoazo metal compounds, acetylacetone metal compounds, aromatic hydroxycarboxylic acids, aromatic dicarboxylic acids, metal compounds of hydroxycarboxylic acids and dicarboxylic acids, aromatic hydroxycarboxylic acids, aromatic monocarboxylic acids and polycarboxylic acids and their metal salts, acid anhydrides and esters, phenol derivatives such as bisphenol, urea derivatives, metal-containing salicylic acid compounds, metal-containing naphtholic acid compounds, boron compounds, quaternary ammonium salts, calixarenes, and charge control resins, etc.

[0095] Examples of charge-controlled resins include polymers or copolymers having sulfonic acid groups, sulfonic acid bases, or sulfonic acid ester groups. Particularly preferred examples of polymers having sulfonic acid groups, sulfonic acid bases, or sulfonic acid ester groups include polymers containing acrylamide monomers or methacrylamide monomers with sulfonic acid groups in a copolymerization ratio of 2% by mass or more, more preferably 5% by mass or more.

[0096] The glass transition temperature (Tg) of the charge-controlled resin is preferably 35 to 90°C, the peak molecular weight (Mp) is 10,000 to 30,000, and the weight-average molecular weight (Mw) is 25,000 to 50,000. When using this charge control, good triboelectric properties can be imparted without affecting the thermal properties required by the toner particles. Furthermore, when the charge-controlled resin contains sulfonic acid groups, for example, the dispersibility of the charge-controlled resin itself in the polymerizable monomer composition and the dispersibility of the colorant, etc., are improved, and the color strength, transparency, and triboelectric properties can be further improved.

[0097] These charge control agents or charge control resins can be used alone or in combination of two or more of them.

[0098] The amount of charge control agent or charge control resin added is preferably from 0.01 parts by weight to 20.00 parts by weight relative to 100.0 parts by weight of binder resin, more preferably from 0.5 to 10.0 parts by weight.

[0099] Methods for manufacturing toners

[0100] There are no particular limitations on the manufacturing method of the colorant; known methods such as pulverization, suspension polymerization, dissolution suspension polymerization, emulsion polymerization, and dispersion polymerization can be used. Here, the colorant is preferably manufactured by the method shown below. That is, the colorant is preferably manufactured by emulsion polymerization.

[0101] The method for manufacturing the toner preferably includes the following steps (1) to (3) performed in the following order:

[0102] (1) Dispersion step: Prepare a dispersion of binder resin microparticles containing binder resin.

[0103] (2) Aggregation step: aggregating the binder resin particles contained in the binder resin particle dispersion to form aggregates, and

[0104] (3) The fusion step involves heating and fusing the aggregates, and

[0105] A boric acid source is added in at least one of the aggregation and fusion steps.

[0106] Furthermore, it is preferable to perform the following steps (4) to (6) in the following order during or after the fusion step:

[0107] (4) Spheroidization step, which involves further heating the aggregates by increasing the temperature.

[0108] (5) Cooling step: The aggregate is cooled at a cooling rate of 0.1℃ / second or higher, and

[0109] (6) Annealing step: The aggregate is heated and held at a temperature equal to or higher than the crystallization temperature or glass transition temperature of the binder resin.

[0110] The toner is preferably manufactured by emulsification aggregation because the shape of the toner can be controlled and boric acid is likely to be uniformly dispersed near the surface of the toner. The details of the emulsification aggregation method will now be described.

[0111] Emulsification aggregation method

[0112] In the emulsion aggregation method, an aqueous dispersion containing toner particles and sufficiently small particles compared to the target particle size is prepared in advance. These particles are aggregated in an aqueous medium until they reach the particle size of the toner particles, and the resin is fused by heating or other means to produce toner particles.

[0113] That is, in the emulsion aggregation method, toner particles are manufactured by performing the following steps: a dispersion step, manufacturing a microparticle dispersion containing the constituent material of the toner particles; an aggregation step, aggregating the microparticles containing the constituent material of the toner particles to control the particle size until the particle size of the toner particles is reached; a melting step, fusing the resin contained in the obtained aggregated particles; a spheroidizing step, controlling the surface shape of the toner by further heating or melting; a subsequent cooling step; a metal removal step, screening the obtained toner and removing excess polyvalent metal ions; a filtration / washing step, washing with ion-exchanged water, etc.; and a step of removing water from the washed toner particles and drying them.

[0114] Preparation steps of resin microparticle dispersion (dispersion step)

[0115] Resin microparticle dispersions can be prepared by known methods, but are not limited to these methods. Examples of known methods include, for example, emulsion polymerization, self-emulsification, phase inversion emulsification by adding an aqueous medium to a resin solution obtained by dissolving it in an organic solvent to emulsify the resin, or forced emulsification by high-temperature treatment of the resin in an aqueous medium without using an organic solvent.

[0116] Specifically, the binder resin is dissolved in an organic solvent capable of dissolving the binder resin, and a surfactant or alkaline compound is added. In the case where the binder resin is a crystalline resin with a melting point, it can be melted by heating to or above its melting point. Next, an aqueous medium is slowly added while stirring with a homogenizer or similar device to precipitate resin particles. Then, the solvent is removed by heating or reducing pressure to prepare an aqueous dispersion of the resin particles. As the organic solvent used to dissolve the resin, any organic solvent capable of dissolving the resin can be used, but from the viewpoint of suppressing the formation of coarse particles, it is preferable to use an organic solvent such as toluene that forms a homogeneous phase with water.

[0117] The surfactants used in the emulsification process described above are not particularly limited, and examples include anionic surfactants such as sulfates and salts, sulfonates, carboxylates, phosphates and soaps; cationic surfactants such as amine salts and quaternary ammonium salts; and nonionic surfactants such as polyethylene glycol type, alkylphenol ethylene oxide adducts and polyol type. Surfactants can be used alone or in combination of two or more of them.

[0118] Examples of basic compounds used in the dispersion step include inorganic bases such as sodium hydroxide and potassium hydroxide, and organic bases such as ammonia, triethylamine, trimethylamine, dimethylaminoethanol, and diethylaminoethanol. Basic compounds can be used alone or in combination of two or more.

[0119] Furthermore, the 50% particle size (D50) of the binder resin particles in the aqueous dispersion of resin particles is preferably 0.05 to 1.0 μm, more preferably 0.05 to 0.4 μm. By adjusting the 50% particle size (D50) based on the volume distribution within the above range, it becomes easy to obtain toner particles with a suitable volume average particle size of 3 to 10 μm.

[0120] The 50% particle size (D50) based on volume distribution was measured using a Nanotrac UPA-EX150 dynamic light scattering particle size analyzer (manufactured by Nikkiso Co., Ltd.).

[0121] Colorant particulate dispersion

[0122] Colorant microparticle dispersions can be used as needed. Colorant microparticle dispersions can be prepared by, but are not limited to, the known methods described below. Therefore, colorant microparticle dispersions can be prepared by mixing colorants, aqueous media, and dispersants using a mixer such as a known stirrer, emulsifier, and disperser. Known dispersants such as surfactants and polymeric dispersants can be used as the dispersant employed herein.

[0123] Whether the dispersant is a surfactant or a polymeric dispersant, it can be removed in the washing steps described later, but from the point of view of washing efficiency, surfactants are preferred.

[0124] Examples of surfactants include anionic surfactants, such as sulfates and salts, sulfonates, phosphates, and soaps; cationic surfactants, such as amine salts and quaternary ammonium salts; and nonionic surfactants, such as polyethylene glycol, alkylphenol ethylene oxide adducts, and polyols. Nonionic or anionic surfactants are preferred. Furthermore, nonionic and anionic surfactants can be used in combination. Surfactants can be used alone or in combination of two or more. The concentration of the surfactant in the aqueous medium is preferably 0.5% to 5% by mass.

[0125] There is no particular limitation on the content of colorant particles in the colorant particle dispersion, but it is preferably 1 to 30% by mass relative to the total mass of the colorant particle dispersion.

[0126] Furthermore, regarding the dispersion particle size of the colorant particles in the aqueous dispersion of the colorant, from the viewpoint of the dispersibility of the colorant in the final toner, the 50% particle size based on the volume distribution (D50) is preferably 0.5 μm or less. Also, for the same reason, it is preferable that the 90% particle size based on the volume distribution (D90) is preferably 2 μm or less. The dispersion particle size of the colorant particles dispersed in the aqueous medium was measured using a dynamic light scattering type particle size analyzer (NANOTRACK UPA-EX150: manufactured by Nikkiso Co., Ltd.).

[0127] Examples of mixers used for dispersing colorants in aqueous media, such as known agitators, emulsifiers, and dispersers, include ultrasonic homogenizers, jet mills, pressure homogenizers, colloid mills, ball mills, sand mills, and paint mixers. These can be used individually or in combination.

[0128] Release agent (aliphatic hydrocarbon compound) particulate dispersion

[0129] Release agent microparticle dispersions can be used as needed. Release agent microparticle dispersions can be prepared by, but are not limited to, the following known methods.

[0130] Release agent particulate dispersions can be manufactured by adding the release agent to an aqueous medium containing a surfactant, heating to or above the melting point of the release agent, dispersing it into granules using a homogenizer with strong shear capacity (e.g., "CLEARMIX WMOTION", manufactured by M Technique Co., Ltd.) or a pressure discharge disperser (e.g., "Gaulin Homogenizer", manufactured by Gaulin Co., Ltd.), and then cooling it to a temperature below the melting point of the release agent.

[0131] Furthermore, the particle size of the release agent microparticle dispersion in the aqueous dispersion of the release agent is preferably 0.03 to 1.0 μm, more preferably 0.1 to 0.5 μm, based on the 50% particle size (D50) of the volume distribution. Additionally, it is preferable that no coarse particles larger than 1 μm are present.

[0132] When the particle size of the release agent microparticle dispersion is within the above-mentioned range, the release agent can exist in a finely dispersed state in the toner, maximizing the outmigration effect during fixing and achieving good release properties. The particle size of the release agent microparticle dispersion obtained by dispersing in an aqueous medium can be measured using a dynamic light scattering particle size analyzer (NANOTRACK UPA-EX150: manufactured by Nikkiso Co., Ltd.).

[0133] Mixing steps

[0134] In the mixing step, a mixture is prepared by mixing a resin microparticle dispersion and at least one of a release agent microparticle dispersion and a colorant microparticle dispersion, as needed. This can be done using known mixing equipment such as homogenizers and mixers.

[0135] The steps involved in forming aggregated particles (aggregation steps)

[0136] In the aggregation step, the particles contained in the mixture prepared in the mixing step are aggregated to form aggregates with a target particle size. At this time, at least one of resin particles and, if necessary, release agent particles and colorant particles are aggregated to form aggregates by adding and mixing a flocculant and applying at least one of heat and / or mechanical force as appropriate.

[0137] Examples of flocculants include organic flocculants, such as quaternary cationic surfactants and polyethyleneimine; inorganic metal salts, such as sodium sulfate, sodium nitrate, sodium chloride, calcium chloride, and calcium nitrate; inorganic ammonium salts, such as ammonium sulfate, ammonium chloride, and ammonium nitrate; and inorganic flocculants, such as divalent or higher metal complexes. In addition, acids can be added to lower the pH and achieve soft aggregation; for example, sulfuric acid and nitric acid can be used.

[0138] The flocculant can be added in dry powder form or as an aqueous solution obtained by dissolving it in an aqueous medium, but it is preferred to add the flocculant in aqueous form to achieve uniform aggregation. Furthermore, it is preferable to add and mix the flocculant at a temperature equal to or lower than the glass transition temperature or melting point of the resin contained in the mixture. Aggregation is achieved relatively uniformly by mixing under these temperature conditions. The flocculant can be mixed into the mixture using known mixing equipment such as homogenizers and mixers. The aggregation step is the step of forming aggregates of the size of toner particles in the aqueous medium. The volume average particle size of the aggregates formed in the aggregation step is preferably 3 to 10 μm. The volume average particle size can be measured using a particle size distribution analyzer (Coulter Multisizer III: Beckman Coulter, Inc.) employing the Coulter method.

[0139] The step of obtaining a dispersion containing toner particles (fusion step)

[0140] In the fusion step, aggregation in the dispersion containing aggregates obtained in the aggregation step is first stopped under the same stirring conditions as in the aggregation step. Aggregation is stopped by adding aggregation-stopping agents such as alkalis or chelating compounds that can adjust the pH, or inorganic salt compounds such as sodium chloride.

[0141] After the dispersion of the aggregated particles in the dispersion is stabilized by the aggregation-stopping agent, the mixture is heated to or above the glass transition temperature or melting point of the binder resin to fuse the aggregated particles and adjust the particle size to the desired value. The 50% particle size (D50) of the toner particles on a volume basis is preferably 3 to 10 μm.

[0142] The steps to obtain the desired surface shape of the toner (spheroidization step)

[0143] A spheroidizing step is preferably performed during or after the fusion step, wherein the temperature is further increased and maintained until the toner particles have the desired roundness or surface shape. The temperature of a specific spheroidizing step is, for example, above 90°C, preferably above 92°C, and more preferably below 95°C. Examples of heating times in the spheroidizing step include heating times of 3 hours or more, 5 hours or more, and 8 hours or more. Through this step, hydrogen bonds from boric acid may form in the toner particles.

[0144] Cooling steps

[0145] Following the spheroidizing step, a cooling step is preferably performed, in which the temperature of the dispersion containing the obtained toner particles is reduced to below the crystallization temperature and / or glass transition temperature of the binder resin. By performing this cooling step, the formation of irregularities on the surface of the toner particles due to volume changes such as expansion or contraction of the material within the toner particles is suppressed, making it easier to control the shape factor SF1 of the cross-section to be 105 to 125, or the contact area ratio (D / S) of the toner to be 14% or less. Furthermore, by increasing the cooling rate, volume changes can be further suppressed, thereby suppressing the formation of indentations on the surface of the toner particles. The desired roundness or surface shape obtained in the spheroidizing step can be maintained, and the shape factor SF1 of the toner and the shape factor SF1 of the toner cross-section can be set to 125 or less, and the contact area ratio (D / S) of the toner can be set to 14% or less. Specifically, the cooling rate is 0.1°C / second or more, preferably 0.5°C / second or more, more preferably 2°C / second or more, and even more preferably 4°C / second or more.

[0146] Annealing steps

[0147] Following the cooling step, an annealing step involving heating and holding is preferably performed at a temperature equal to or higher than the crystallization temperature or glass transition temperature of the binder resin, and when a release agent is present, the temperature is equal to or lower than the crystallization temperature of the release agent. By undergoing the annealing step, volume change can be further suppressed, thereby inhibiting the formation of indentations on the surface of the toner particles. Therefore, the desired roundness or surface shape obtained through the cooling step can be maintained, the shape factor SF1 of the toner and the shape factor SF1 of the toner cross-section can be set to 125 or less, and the contact area ratio (D / S) of the toner can be controlled to 14% or less. Specifically, the annealing temperature is 45 to 75°C, preferably 50 to 70°C, more preferably 55 to 65°C. The heat treatment time in the annealing step is, for example, 5 hours or less, preferably 2 to 3 hours.

[0148] Post-processing steps

[0149] In the manufacturing method of toner, further post-processing steps such as washing, solid-liquid separation, and drying can be performed to obtain toner particles in a dry state.

[0150] External addition steps

[0151] The obtained toner particles can be used as toner as is.

[0152] In the external addition step, inorganic microparticles are externally added to the toner particles obtained in the drying step as needed. Specifically, it is preferable to add and mix inorganic microparticles such as silica or resin microparticles such as vinyl resins, polyester resins, and silicone resins by applying shear force in the dry state. The silica microparticles are preferably mixed at an amount of 1.2 to 1.8 parts by mass relative to 100 parts by mass of toner particles for 2 to 16 minutes, more preferably at an amount of 1.3 to 1.7 parts by mass for 6 to 10 minutes. When silica microparticles are added and mixed at the above-mentioned amounts and mixing times, the coverage of the silica microparticles on the surface of the toner particles, as measured by X-ray photoelectron spectroscopy, is easily controlled within the range of 50 to 80% area, and the dispersion evaluation index of the silica microparticles on the toner surface is easily controlled within the range of 0.10 to 2.00.

[0153] The manufacturing method of the toner preferably includes a shell-forming step, which forms aggregated particles (core particles) through an aggregation step, and then further adds resin microparticles containing a shell resin to induce aggregation and form a shell. That is, the toner particles preferably have a core particle containing a binder resin and a shell on the surface of the core particle. The shell resin can be the same as the binder resin, or other resins can be used. The amount of shell resin added is preferably 1 to 10 parts by weight, more preferably 2 to 7 parts by weight, relative to the binder resin contained in 100 parts by weight of the core particle.

[0154] In this case, the preferred method for manufacturing the toner includes the following steps:

[0155] (1) Dispersion step: Prepare a dispersion of binder resin microparticles containing binder resin.

[0156] (2-1) The aggregation step of agglomerating the binder resin particles contained in the binder resin particle dispersion to form aggregates.

[0157] (2-2) A shell-forming step in which resin particles containing shell resin are further added to a dispersion of binder resin particles containing aggregates, and the resin particles containing shell resin are aggregated to form aggregates with shells.

[0158] (3) Fusion step: The aggregate is heated and fused together.

[0159] That is, the above-mentioned aggregation step (2) (aggregation step of aggregating the adhesive resin particles contained in the adhesive resin particle dispersion to form aggregates) preferably includes the following steps (2-1) and (2-2).

[0160] (2-1) The aggregation step of agglomerating the binder resin particles contained in the binder resin particle dispersion to form aggregates, and

[0161] (2-2) A shell-forming step in which resin particles containing shell resin are further added to a dispersion of binder resin particles containing aggregates and the resin particles containing shell resin are aggregated to form aggregates having shells.

[0162] Furthermore, it is more preferable to perform the following steps (4) to (6) in the following order during or after the fusion step:

[0163] (4) Spheroidization step, which involves further heating the aggregates by increasing the temperature.

[0164] (5) Cooling step: The aggregate is cooled at a cooling rate of 0.1℃ / second or higher, and

[0165] (6) Annealing step: The aggregate is heated and held at a temperature equal to or higher than the crystallization temperature or glass transition temperature of the binder resin.

[0166] To promote the inclusion of boric acid near the surface of the toner particles, it is preferable to add the boric acid source together with the resin microparticles containing the shell resin to the dispersion containing the aggregates during the shell formation step.

[0167] The boric acid source can be boric acid or a compound that can be converted into boric acid during toner manufacturing through pH control, etc. For example, at least one selected from the group consisting of boric acid, borax, organoboronic acids, borates, borate esters, etc., can be mentioned. For example, a boric acid source can be added and controlled to include boric acid in the aggregates. Preferably, the pH is controlled to acidic conditions during the aggregation step, followed by the shell-forming step.

[0168] Boric acid can exist in the aggregate in an unsubstituted state. The boric acid source is preferably at least one selected from the group consisting of boric acid and borax. When manufacturing a toner in an aqueous medium, from the viewpoint of reactivity and manufacturing stability, it is preferable to add a borate as the boric acid source. Specifically, the boric acid source more preferably includes at least one selected from the group consisting of sodium tetraborate, borax, ammonium borate, etc., and more preferably borax.

[0169] Borax is a decahydrate of sodium tetraborate (Na₂B₄O₇) and converts to boric acid in an acidic aqueous solution. Therefore, borax is preferred when used in an acidic environment in an aqueous medium. As a method of addition, it can be added as a dry powder or by dissolving it in an aqueous solution obtained in the aqueous medium, but to induce uniform aggregation, it is preferred to add it in the form of an aqueous solution. The concentration of the aqueous solution can be appropriately varied depending on the concentration in the toner, for example, from 1 to 20% by mass. To convert it to boric acid, it is preferable to set the pH to acidic conditions before, during, or after addition. For example, it can be controlled to be from 1.5 to 5.0, preferably from 2.0 to 4.0.

[0170] Next, a method for measuring various physical properties according to this disclosure will be described.

[0171] Measurement of weight-average particle size (D4) and number-average particle size (D1) of toner or toner particles

[0172] The weight-average particle size (D4) and number-average particle size (D1) of the toner or toner particles are calculated as follows. A precise particle size distribution measurement device based on the pore resistance method with a 100 μm orifice (Coulter Counter Multisizer 3 (registered trademark), manufactured by Beckman Coulter, Inc.) and dedicated software for setting measurement conditions and analyzing measurement data (Beckman Coulter Multisizer 3 Version 3.51, manufactured by Beckman Coulter, Inc.) are used in the measurement. Measurements are performed using 25,000 effective measurement channels, and then the measurement data are analyzed and calculated.

[0173] A solution obtained by dissolving premium sodium chloride at a concentration of about 1% by mass in ion-exchange water, such as "ISOTON II" (made by Beckman Coulter), can be used as an aqueous electrolyte solution for measurement.

[0174] Before performing measurements and analysis, configure the dedicated software as follows: In the "Standard Operating Method (SOM) Change" interface of the dedicated software, set the total count for the control mode to 50,000 particles; set the number of measurements to 1; and set the Kd value to the value obtained using "Standard Particle 10.0 μm" (Beckman Coulter). Automatically set the threshold and noise level by pressing the "Threshold / Noise Level Measurement Button". Additionally, set the current to 1,600 μA; the gain to 2; the electrolyte solution to ISOTON II; and check the "Flush Port after Measurement" option. In the "Pulse to Particle Size Conversion Setting" interface of the dedicated software, set the bin interval to logarithmic particle size; set the particle diameter bin to 256 particle diameter bins; and set the particle size range to 2 to 60 μm.

[0175] The specific measurement method is as follows.

[0176] 1. Pour 200 mL of electrolyte solution into a 250 mL round-bottom glass beaker specifically designed for Multisizer 3, place the beaker on the sample stage, and rotate the stir bar counterclockwise at 24 rpm. Use the "Venere rinse" function in the dedicated software to remove contaminants and air bubbles from the ureter.

[0177] 2. Place approximately 30 mL of the electrolyte solution into a 100 mL flat-bottomed glass beaker. Add approximately 0.3 mL of a diluent obtained by diluting "Contaminon N" (a 10% by mass aqueous solution of a neutral detergent for cleaning precision measuring instruments, pH 7, and containing nonionic surfactants, anionic surfactants, and organic builders, manufactured by Wako Pure Chemical Industries, Ltd.) with approximately three times the mass of deionized water as a dispersant.

[0178] 3. Prepare an ultrasonic disperser (Ultrasonic Dispersion System Tetora 150, manufactured by Nikkaki Bios Co., Ltd.), with a power output of 120W, which contains two oscillators with an oscillation frequency of 50kHz, staggered by 180°. Add the prescribed amount of ion-exchanged water to the water tank of the ultrasonic disperser, and add approximately 2 mL of Contaminon N to the tank.

[0179] 4. Place the beaker mentioned in step (2) above into the beaker fixing hole on the ultrasonic disperser, and start the ultrasonic disperser. Adjust the height of the beaker to maximize the resonance state of the electrolyte aqueous solution surface inside the beaker.

[0180] 5. While irradiating the electrolyte solution in the beaker mentioned in section (4) above with ultrasound, add approximately 10 mg of toner one small dot at a time to the electrolyte solution and disperse it therein. Continue the ultrasonic dispersion treatment for another 60 seconds. When performing ultrasonic dispersion, adjust the temperature of the water bath appropriately to a temperature between 10°C and 40°C.

[0181] 6. Using a pipette, drop the electrolyte aqueous solution mentioned in part (5) above, in which the colorant is dispersed, into the round-bottom beaker mentioned in part (1) above, which is placed on the sample stage, and adjust the measurement concentration to about 5%. Perform the measurement until the number of particles measured reaches 50,000.

[0182] 7. Calculate the weight-average particle size (D4) and number-average particle size (D1) by analyzing the measurement data using the included dedicated software. When the dedicated software is set to Graph / Volume %, the "Average Diameter" on the "Analysis / Volume Baseline Statistics (Arithmetic Mean)" interface is the weight-average particle size (D4). When the dedicated software is set to Graph / Number %, the "Average Diameter" on the "Analysis / Numerical Baseline Statistics (Arithmetic Mean)" interface is the number-average particle size (D1).

[0183] Method for measuring the average roundness of toners

[0184] Under the measurement and analysis conditions of the calibration operation, the average roundness of the toner was measured using an “FPIA-3000” flow particle image analyzer (Sysmex Corporation).

[0185] After adding an appropriate amount of surfactant (alkylbenzene sulfonate) as a dispersant to 20 mL of deionized water, 0.02 g of the measurement sample was added, and the sample was dispersed for 2 minutes using a benchtop ultrasonic cleaner disperser (trade name: VS-150, manufactured by Velvo-Clear Co., Ltd.) with an oscillation frequency of 50 kHz and an electrical output of 150 W to prepare the dispersion for measurement. The dispersion was then appropriately cooled to a temperature between 10 and 40 °C.

[0186] A flow-through particle image analyzer equipped with a standard objective lens (10x) was used for the measurement, and a particle sheath "PSE-900A" (manufactured by Sysmex Corporation) was used as the sheath fluid. The dispersion prepared according to the above procedure was introduced into the flow-through particle image analyzer, and 3000 toner particles were measured in total count mode in HPF measurement mode. The binarization threshold for particle analysis was set to 85%, the diameter of the analyzed particles was limited to the circumsistent diameter of 1.98 to 19.92 μm, and the average sphericity of the toner (particles) was obtained.

[0187] During the measurement, autofocus adjustment is performed using standard latex particles (e.g., 5100A (trade name), manufactured by Duke Scientific Corporation, diluted with deionized water) before the measurement begins. Subsequently, focus adjustment is preferably performed every 2 hours from the start of the measurement.

[0188] Method for measuring the shape factor SF1 of toners

[0189] The toner was observed using an FE-SEM (trade name: S-4700, manufactured by Hitachi, Ltd.) at a magnification of 2000x.

[0190] The toner image was analyzed using image analysis software (trade name: analyzeSIS Pro) manufactured by Olympus Corporation. The absolute maximum length R, perimeter L, and cross-sectional area S of the toner were obtained. From the obtained perimeter of the toner, the equivalent circular diameter r was obtained using the formula r = L / π. Particles within ±10% of the weight-average particle size D4 obtained using the Coulter counter and the above method were taken as the corresponding particles.

[0191] Fifty particles were randomly selected, and the average value of their absolute maximum cross-sectional length was taken as Rave, and the average value of their cross-sectional area was taken as Save. The shape factor SF1 (cross-section) of the toner was obtained by the following formula.

[0192] Shape factor SF1 = (Rave 2 (×π) / (Save×4)×100

[0193] Method for measuring the shape factor SF1 of toner cross section

[0194] The shape factor of the toner was measured using the CP cross-section method with a cross-section polishing machine (trade name: SM-09010) manufactured by JEOL Ltd. Then, the cross-section of the toner was prepared as described below.

[0195] A carbon double-sided pressure-sensitive adhesive sheet was partially bonded to a silicon wafer, and a Mo mesh (diameter: 3 mm / thickness: 30 μm) was fixed on top. A layer of toner (approximately the thickness of one toner particle) was then applied. After platinum was vapor-deposited on top, a cross-section of the toner was formed using a section polisher under an accelerating voltage of 4 kV and a processing time of 3 hours.

[0196] The resulting toner cross section was observed using an FE-SEM (trade name: S-4700; manufactured by Hitachi, Ltd.) at a magnification of 2000x.

[0197] The image of the toner cross-section was analyzed using image analysis software (trade name: analyzeSIS Pro) manufactured by Olympus Corporation. The absolute maximum length R, perimeter L, and cross-sectional area S of the toner cross-section were obtained. From the obtained perimeter of the toner, the circular equivalent diameter r was obtained by using the circular equivalent diameter r = L / π. Objects within ±10% of the weight-average particle size D4 obtained by the above method using a Coulter counter were taken as the corresponding particles.

[0198] Fifty particles were randomly selected, and the average value of their absolute maximum cross-sectional length was taken as Rave, and the average value of their cross-sectional area was taken as Save. The shape factor SF1 of the toner cross-section was obtained by the following formula.

[0199] The shape factor SF1 of the cross section = (Rave 2 (×π) / (Save×4)×100

[0200] Method for measuring the contact area ratio (D / S) of toners

[0201] Prepare a colorless, transparent glass slide (approximately 2 mm thick) with a 22 μm opening. Spread the toner on a sieve and sieve it from a height of 10 cm by applying vibration for 10 seconds, ensuring a small amount of toner is evenly distributed on the slide. Then, using a laser microscope (KH-3000, manufactured by HIROX Co., Ltd.), increase the magnification to 100x and capture an image of the toner from the slide side. This image is then imported into an image analysis device. Image analysis is performed by randomly sampling 50 particles from the image captured using analysis software (Image-Pro Plus 4.5, manufactured by Media Cybernetics, Inc.). In the image analysis, assuming the area of ​​the toner in contact with the glass surface is D, and the projected area of ​​the entire toner is S, then D / S is the ratio of the toner's contact area.

[0202] IR analysis of toner (particles) using the ATR method with germanium (Ge) as the ATR crystal.

[0203] ATR-IR analysis of the toner was performed using the following method. Toner particles obtained by removing external additives from the toner using the method described below can also be used as samples.

[0204] IR analysis was performed using the ATR method on a Fourier transform infrared spectrometer (Spectrum One: PerkinElmer Co.) equipped with a Universal ATR Sampling Accessory. The specific measurement procedure is as follows.

[0205] The incident angle of the infrared light (λ = 5 μm) was set to 45°. A Ge ATR crystal (refractive index = 4.0) was used as the ATR crystal. Other conditions are as follows.

[0206] scope

[0207] Starting point: 4000cm -1

[0208] Finish line: 650cm -1 (Ge ATR crystal)

[0209] Duration

[0210] Number of scans: 16

[0211] Resolution: 4.00cm -1

[0212] Advanced: with CO2 / H2O correction

[0213] (1) A Ge ATR crystal (refractive index = 4.0) is attached to the device.

[0214] (2) Set the scan type to background and the unit to EGY to measure the background.

[0215] (3) Set the scan type to sample and the unit to A.

[0216] (4) Weigh 0.01g of toner or the total amount of toner particles onto the ATR crystal.

[0217] (5) Apply pressure to the sample using a pressure arm (force gauge is 90).

[0218] (6) Measure the sample.

[0219] 1380cm -1 The absorption spectrum. When at 1380 cm⁻¹ -1 When an absorption peak is detected nearby, it is determined that a peak corresponding to boric acid has been detected.

[0220] Measurement of boron intensity in fluorescence X-ray diffraction of toner particles

[0221] The boron intensity in the fluorescence X-ray measurement of toner particles was measured using the calibration curve method. Specifically, an aluminum ring (40 mm inner diameter, 43 mm outer diameter, and 5 mm height) was placed on a sample forming mold of a semi-automatic MiniPress machine (manufactured by Specac Limited). Approximately 3 g of toner particles were placed inside and pressed at a pressure of 15 t for 1 minute to prepare pellets for measurement. Pellets with a thickness of approximately 3 mm and a diameter of approximately 40 mm were used.

[0222] Measurements were performed under the following conditions using a wavelength dispersive fluorescence X-ray analyzer, "Axios" (manufactured by PANalytical Co.), and dedicated software, "SuperQ ver. 4.0F" (manufactured by PANalytical Co.), for setting measurement conditions and analyzing measurement data. Rh was used as the anode of the X-ray tube, the measurement atmosphere was vacuum, the measurement diameter (collimator mask diameter) was 27 mm, and the measurement time was 10 seconds. In the case of boron, a proportional counter (PC) was used for detection.

[0223] Measurements were performed under the above conditions, boron was identified based on the peak position of the obtained X-rays, and the count rate (unit: cps) was measured as the number of X-ray photons per unit time.

[0224] A method for obtaining toner particles by removing external additives from toners.

[0225] A total of 160 g of sucrose (manufactured by Kishida Chemical Co., Ltd.) was added to 100 mL of ion-exchanged water and dissolved in a water bath to prepare a sucrose concentrate. A total of 31 g of the sucrose concentrate and 6 mL of Contaminone N (a 10% by mass aqueous solution of a neutral detergent for cleaning precision measuring instruments, containing nonionic surfactants, anionic surfactants, and organic detergent builders, pH 7, manufactured by Wako Pure Chemical Industries, Ltd.) were placed in a centrifuge tube (50 mL capacity) to prepare a dispersion. 1.0 g of toner was added to the dispersion, and the toner clumps were loosened with a spatula or similar tool. The centrifuge tube was shaken for 20 minutes at 300 spm using a shaker (AS-1N, sold by AS ONE Corporation). After shaking, the solution was transferred to a 50 mL glass tube for centrifugation using a centrifuge (H-9R, manufactured by Kokusan Co., Ltd.) at 3500 rpm for 30 minutes.

[0226] This process separates the toner particles from the external additives. Visually confirm the complete separation of the toner particles and the aqueous solution, and collect the separated toner particles on the top layer using a spatula or similar tool. Filter the collected toner particles through a vacuum filter, and then dry them in a desiccator for at least one hour to obtain a sample for measurement. This process is repeated multiple times to ensure the required quantity.

[0227] Method for measuring the coverage of silica microparticles on the surface of toner particles.

[0228] The coverage of the toner particles with silica microparticles was determined by the following method. First, the atomic weight of silicon (hereinafter referred to as Si) from the silica microparticles present on the surface of the toner particles was measured by ESCA (X-ray photoelectron spectroscopy).

[0229] The ESCA instruments and measurement conditions are as follows.

[0230] Equipment used: Quantum 2000, manufactured by ULVAC-PHI, Inc.

[0231] Analysis method: Narrow analysis

[0232] Measurement conditions:

[0233] X-ray source: Al-Kα

[0234] X-ray conditions: beam diameter 100μm, 25W, 15kV

[0235] Photoelectron absorption angle: 45°

[0236] Energy: 58.70 eV

[0237] Measurement range:

[0238] In the analytical method, firstly, the peak of the C-C bond originating from the carbon 1s orbital is corrected to 285 eV. Then, using the relative sensitivity factor provided by ULVAC-PHI, Inc., the ratio of Si from silicon dioxide to the total amount of constituent elements in the toner, "A (atomic %)", is calculated from the peak area originating from the silicon 2p orbital (where the peak apex is detected at 100 to 105 eV).

[0239] Next, the amount of Si relative to the silica monomer (simple substance) used in the toner is measured using the same method described above, and the ratio of Si from silica to the total amount of constituent elements in the silica monomer, "B (atomic %)", is obtained. This ratio B (atomic %) is considered to be the value for 100% coverage.

[0240] At this point, the silica coverage is calculated using the following formula:

[0241] Silica coverage (%) = Ratio A / Ratio B × 100

[0242] When using both a first external additive and a second external additive, where both are silicon dioxide, the amount of Si in the external additive monomer is the same as that in both the first and second external additives, and therefore the measurement is performed using the method described above.

[0243] Meanwhile, when a substance other than silicon dioxide is used as the first external additive, the amount of Si in the simple substance of the external additive differs between the first and second external additives, and is therefore measured by the following method.

[0244] The ratio A1 of Si in the toner with only the first external additive added is measured, and similarly, the ratio A2 of Si in the toner with only the second external additive added is measured. The silica coverage in this case is calculated using the aforementioned ratio of Si, "B (atomic %)", by the following formula.

[0245] Silica coverage (%) = (Ratio A1 / Ratio B + Ratio A2 / Ratio B) × 100

[0246] Dispersion evaluation index of silica particles on the surface of toner

[0247] The dispersion evaluation index of silica particles on the surface of the toner was calculated using a scanning electron microscope "S-4800". Toners with externally added silica particles were observed in the same field of view at 10,000x magnification and an accelerating voltage of 1.0 kV. The index was calculated from the observed images using the image processing software "ImageJ" (available at https: / / imagej.nih.gov / ij / ) in the following manner.

[0248] Binarization was performed to extract only silica microparticles. Specifically, energy-dispersive X-ray spectroscopy (EDX) analysis was performed on the toner surface within the same field of view to determine whether the particles were silica microparticles. The number of silica microparticles, n, and the centroid coordinates of all silica microparticles were calculated, and the distance dnmin to the nearest silica microparticle for each microparticle was calculated.

[0249] Assuming the average nearest distance between silica particles in the image is dave, the dispersion is represented by the following formula:

[0250]

[0251] The dispersion of 50 randomly observed toner particles was obtained using the above procedure, and the average value was used as the dispersion evaluation index. The smaller the dispersion evaluation index, the better the dispersion.

[0252] Example

[0253] The invention is described in more detail below by way of examples. The invention is not limited to the following examples. In the text, "parts" in the recipes are based on mass unless otherwise explicitly stated.

[0254] Manufacturing example of toner 1

[0255] Preparation of silica microparticles 1

[0256] A total of 10.0 parts of polydimethylsiloxane (viscosity = 100 mm) 2 / s) sprayed onto 100 parts of fumed silica (trade name: AEROSIL 380S, BET method, specific surface area 380m²) 2 / g, with a number-average particle size of 7nm (manufactured by Nippon Aerosil Co., Ltd.), and continued stirring for 30 minutes. Then, while stirring, the temperature was increased to 300°C and stirred for another 2 hours to prepare silica microparticles 1.

[0257] Synthesis of Polyester Resin 1

[0258] • Bisphenol A ethylene oxide 2mol adduct: 9mol parts

[0259] • Bisphenol A propylene oxide 2mol adduct: 95mol parts

[0260] ·Terephthalic acid: 50 mol

[0261] Fumaric acid: 30 mol parts

[0262] • Dodecenylsuccinic acid: 25 mol

[0263] The monomers were placed in a flask equipped with a stirrer, nitrogen inlet, temperature sensor, and distillation column. The temperature was raised to 195°C over 1 hour, and the reaction system was stirred uniformly. A total of 1.0 part of distearate was added to 100 parts of these monomers. Meanwhile, while distilling off the generated water, the temperature was raised from 195°C to 250°C over 5 hours, and a dehydration condensation reaction was carried out at 250°C for an additional 2 hours.

[0264] As a result, a polyester resin 1 with a glass transition temperature of 60.2℃, an acid value of 16.8 mg KOH / g, a hydroxyl value of 28.2 mg KOH / g, a weight-average molecular weight of 11,200, and a number-average molecular weight of 4,100 was obtained.

[0265] Synthesis of Polyester Resin 2

[0266] • Bisphenol A ethylene oxide 2mol adduct: 48mol parts

[0267] • Bisphenol A propylene oxide 2mol adduct: 48mol parts

[0268] ·Terephthalic acid: 65 mol parts

[0269] • Dodecenylsuccinic acid: 30 mol

[0270] The monomers were placed in a flask equipped with a stirrer, nitrogen inlet, temperature sensor, and distillation column. The temperature was raised to 195°C over 1 hour, and the reaction system was stirred uniformly. A total of 0.7 parts of distearate tin was added to 100 parts of these monomers. Meanwhile, while distilling off the generated water, the temperature was raised from 195°C to 240°C over 5 hours, and a dehydration condensation reaction was carried out at 240°C for another 2 hours. Then, the temperature was lowered to 190°C, and 5 mol of trimellitic anhydride was gradually added, and the reaction was continued at 190°C for 1 hour.

[0271] As a result, polyester resin 2 with a glass transition temperature of 55.2℃, an acid value of 14.3 mg KOH / g, a hydroxyl value of 24.1 mg KOH / g, a weight-average molecular weight of 43,600, and a number-average molecular weight of 6,200 was obtained.

[0272] Preparation of Resin Particle Dispersion 1

[0273] • Polyester resin 1:100 parts

[0274] Methyl ethyl ketone: 50 parts

[0275] Isopropyl alcohol: 20 parts

[0276] The methyl ethyl ketone and isopropanol were placed in a container. Then, polyester resin 1 was gradually added, stirred, and completely dissolved to obtain a polyester resin 1 solution. The container containing the polyester resin 1 solution was set to 65°C, and 10% ammonia solution was gradually added dropwise to a total of 5 parts while stirring. 230 parts of deionized water were then gradually added dropwise at a rate of 10 ml / min to induce phase inversion emulsification. Furthermore, the solvent was removed by reduced pressure using an evaporator to obtain a resin particle dispersion 1 of polyester resin 1. The volume average particle size of the resin particles was 135 nm. The solid content of the resin particles was adjusted to 20% using deionized water.

[0277] Preparation of resin particle dispersion 2

[0278] • Polyester resin 2: 100 parts

[0279] Methyl ethyl ketone: 50 parts

[0280] Isopropyl alcohol: 20 parts

[0281] The aforementioned methyl ethyl ketone and isopropanol were placed in a container. Then, polyester resin 2 was gradually added, stirred, and completely dissolved to obtain a polyester resin 2 solution. The container containing the polyester resin 2 solution was set to 40°C, and while stirring, a 10% ammonia solution was gradually added dropwise to a total of 3.5 parts, followed by the gradual addition of 230 parts of deionized water at a rate of 10 ml / min to induce phase inversion emulsification. Furthermore, the solvent was removed under reduced pressure to obtain a resin particle dispersion 2 of polyester resin 2. The volume average particle size of the resin particles was 155 nm. The solid content of the resin particles was adjusted to 20% using deionized water.

[0282] Preparation of colorant particle dispersion

[0283] • Copper phthalocyanine (pigment blue 15:3): 45 parts

[0284] • Ionic surfactant Neogen RK (manufactured by DKS Co., Ltd.): 5 parts

[0285] • Ion-exchanged water: 190 parts

[0286] The above components were mixed and dispersed for 10 minutes using a homogenizer (ULTRA-TURRAX, manufactured by IKA), and then dispersed for 20 minutes using an ULTIMIZER (anti-collision wet mill: manufactured by Sugino Machine Limited) at a pressure of 250 MPa to obtain a colorant particle dispersion with a volume average particle size of 120 nm and a solid content of 20%.

[0287] Preparation of release agent particle dispersion

[0288] • Release agent (hydrocarbon wax, melting point: 79℃): 15 parts

[0289] • Ionic surfactant Neogen RK (manufactured by DKS Co., Ltd.): 2 parts

[0290] • Ion-exchanged water: 240 parts

[0291] The above components were heated to 100°C and fully dispersed using an IKA ULTRA-TURRAX T50 homogenizer. Then, they were heated to 115°C using a pressure-discharge Gaulin homogenizer and dispersed for 1 hour to obtain a release agent particle dispersion with a volume average particle size of 160 nm and a solid content of 20%.

[0292] Manufacturing of Toner Particle 1

[0293] • Resin particle dispersion 1:500 parts

[0294] • Resin particle dispersion 2:400 parts

[0295] • Colorant particle dispersion: 50 parts

[0296] • Release agent granule dispersion: 80 parts

[0297] First, as a nucleation step, the above materials were placed in a round stainless steel flask and mixed. Then, they were dispersed for 10 minutes at 5000 rpm using an ULTRA-TURRAX T50 homogenizer (IKA manufactured). After adding 1.0% nitric acid aqueous solution and adjusting the pH to 3.0, the mixture was heated to 58°C in a water bath with a stirring blade, adjusting the rotation speed as needed.

[0298] Use Coulter Multisizer III appropriately to confirm the volume average particle size of the formed aggregates. When aggregates (cores) with a size of 5.0 μm are formed, perform a shell formation step by adding the following materials and stirring for another hour to form a shell.

[0299] • Resin particle dispersion 1:40 parts

[0300] • Ion-exchanged water: 300 parts

[0301] • 10.0% by mass borax aqueous solution: 19 parts

[0302] (Borax: Sodium tetraborate decahydrate, manufactured by Wako Pure Chemical Industries, Ltd.)

[0303] Subsequently, as a spheroidization step, the pH was adjusted to 9.0 using a 5% sodium hydroxide aqueous solution, and the mixture was heated to 92°C while continuing to stir.

[0304] When the desired surface shape is obtained, heating is stopped, and as a cooling step, the surface is cooled to 40°C by rapidly adding ice at a cooling rate of 10°C / second or higher. Additionally, as an annealing step, the surface is annealed at 55°C for 3 hours.

[0305] The mixture was then cooled to 25°C, filtered, and subjected to solid-liquid separation, followed by washing with deion-exchanged water. After washing, the mixture was dried using a vacuum dryer to obtain toner particles 1 with a weight-average particle size (D4) of 6.8 μm.

[0306] Toner particles 1 were added externally. Using a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.), a total of 100.0 parts of toner particles 1 and 1.3 parts of silica microparticles 1 were dry-mixed for 7 minutes to obtain toner 1. Table 2 shows the physical properties of the obtained toner 1.

[0307] Manufacturing examples of toners 2 to 14

[0308] Except for changes to the formulations and conditions shown in Table 1, toners 2 to 14 were obtained in the same manner as toner 1. Table 2 shows the physical properties of toners 2 to 14.

[0309] Manufacturing example of toner 15

[0310] • Polyester resin 1: 60.0 parts

[0311] • Polyester resin 2: 40.0 parts

[0312] • Copper phthalocyanine pigment (pigment blue 15:3): 6.5 parts

[0313] • Release agent (hydrocarbon wax, melting point 79℃): 5.0 parts

[0314] • Plasticizer (ethylene glycol distearate): 15.0 parts

[0315] • Boric acid powder (manufactured by Wako Pure Chemical Industries, Ltd.): 1.5 parts

[0316] The above materials were premixed using an FM mixer (manufactured by Nippon Coke Industries Co., Ltd.) and then melt-mixed using a twin-screw compounding extruder (PCM-30 type, manufactured by Ikegai Iron Works Co., Ltd.).

[0317] The obtained mixture was cooled and coarsely pulverized using a hammer mill. Then, 130 parts of ethyl acetate were added, and the mixture was heated to 80°C and stirred for 1 hour using a TKHomomixer (Special Machinery Chemical Industry Co., Ltd.) at a rotation speed of 5000 rpm. The mixture was then cooled to 30°C to obtain a solution.

[0318] A total of 400 parts water and 5 parts Eleminol MON-7 (manufactured by Sanyo Chemical Industries, Ltd.) were placed in a separate container and set to 30°C. Then, while stirring with a TK Homomixer (Special Machinery Chemical Industry Co., Ltd.) at 13,000 rpm, 100 parts of the above solution were added, and the mixture was further stirred for 20 minutes to obtain a slurry. The obtained slurry was desolvated at 30°C under reduced pressure for 8 hours while gently stirring, then matured at 45°C for 4 hours. The slurry was then subjected to washing, filtration, and drying steps to obtain toner particles 15. Toner particles 15 were externally added in the same manner as toner 1 to obtain toner 15. Table 2 shows the physical properties of toner 15.

[0319] Comparison of manufacturing examples of toners 1, 2, 4, and 5

[0320] Comparative toners 1, 2, 4, and 5 were obtained in the same manner as toner 1, except that the formulations and conditions shown in Table 1 were modified. Table 2 shows the physical properties of comparative toners 1, 2, 4, and 5.

[0321] Comparative manufacturing example of toner 3

[0322] • Polyester resin 1:50 parts

[0323] • Polyester resin 2:40 parts

[0324] Copper Phthalocyanine (Pigment Blue 15:3): 8 parts

[0325] • Release agent (hydrocarbon wax, melting point 79℃): 4 parts

[0326] • Boric acid powder (manufactured by Wako Pure Chemical Industries, Ltd.): 1.5 parts

[0327] The above materials were premixed using an FM mixer (manufactured by Nippon Coke Industries Co., Ltd.) and then melt-mixed using a twin-screw compounding extruder (PCM-30 type, manufactured by Ikegai Iron Works Co., Ltd.).

[0328] The obtained mixture was cooled, coarsely pulverized with a hammer mill, and then pulverized with a mechanical pulverizer (T-250, manufactured by Turbo Industries Co., Ltd.). The finely pulverized powder was then classified using a multi-stage classifier employing the Coanda effect to obtain comparative toner particles 3 with a weight average particle size (D4) of 7.0 μm.

[0329] Comparative toner particles 3 were externally added in the same manner as in the manufacture of toner 1 to obtain comparative toner 3. Table 2 shows the physical properties of comparative toner 3.

[0330] [Table 1]

[0331]

[0332] [Table 2]

[0333]

[0334] In Table 2, “CE” represents “Comparative Example” and “CT” represents “Comparative Toner”.

[0335] Example 1

[0336] The following evaluation was performed on toner 1.

[0337] Toner Evaluation

[0338] The modified commercially available Canon LBP7600C laser beam printer was used. The modification involved changing the gears and software of the machine body to set the rotational speed of the developing roller to 1.5 times the circumferential speed of the drum.

[0339] Under low temperature and low humidity conditions (15℃ / 10% RH), the following method was used on LETTER size Business 4200 paper (made by XEROX, 75g / m²). 2 Output image on ).

[0340] (1) Output three solid images.

[0341] (2) Output three grid patterns with lines of thickness 100μm (thickness in the electrostatic latent image) spaced 1cm apart.

[0342] (3) Output a solid image, and then use Mylar tape to cover and peel off the residual toner on the photosensitive component after the solid image has been transferred.

[0343] (4) Output 4000 images with a print percentage of 1%. Then, output three more grid patterns.

[0344] (5) Output three solid images.

[0345] (6) Output three grid patterns with lines of thickness 100μm (thickness in the electrostatic latent image) spaced 1cm apart.

[0346] (7) Output a solid image, and then use Mylar tape to cover and peel off the residual toner on the photosensitive component after the solid image has been transferred.

[0347] Initial transferability

[0348] Apply the tape obtained in (3) and the un-adhesive tape to LETTER size Business 4200 paper (75g / m²). 2 (Made by XEROX Corp.). The reflectivity difference on each strip surface is evaluated based on the following benchmarks. A rating of C or higher corresponds to an acceptable level.

[0349] A: Less than 0.6%.

[0350] B: 0.6% or more but less than 1.2%.

[0351] C: 1.2% or more but less than 2.0%.

[0352] D: Above 2.0% and less than 3.0%.

[0353] E: 3.0% or more.

[0354] Initial transfer dust

[0355] The third grid pattern image output in (2) was observed using a magnifying glass with a magnification of 25x, and the transfer dust (the phenomenon of toner scattered around the character and line images) was evaluated based on the following criteria. An evaluation of C or above corresponds to an acceptable level.

[0356] A: The lines are very clear, with almost no dust transfer.

[0357] B: The lines are clear, with only a small amount of splattered toner.

[0358] C: There was some splattering of toner, but the lines are relatively clear.

[0359] D: There are many splashes of toner, and the lines are blurred.

[0360] Transferability in durability testing

[0361] Apply the tape obtained in (7) and the un-adhesive tape to LETTER size Business 4200 paper (75g / m²). 2 (Made by XEROX Corp.). The reflectivity difference on each strip surface is evaluated based on the following benchmarks. A rating of C or higher corresponds to an acceptable level.

[0362] A: Less than 0.6%.

[0363] B: 0.6% or more but less than 1.2%.

[0364] C: 1.2% or more but less than 2.0%.

[0365] D: Above 2.0% and less than 3.0%.

[0366] E: 3.0% or more.

[0367] Transfer dust in durability testing

[0368] The third grid pattern image output in (6) was observed using a magnifying glass with a magnification of 25x, and the transfer dust (the phenomenon of toner scattered around the character and line images) was evaluated based on the following criteria. An evaluation of C or above corresponds to an acceptable level.

[0369] A: The lines are very clear, with almost no dust transfer.

[0370] B: The lines are clear, with only a small amount of splattered toner.

[0371] C: There was some splattering of toner, but the lines are relatively clear.

[0372] D: There are many splashes of toner, and the lines are blurred.

[0373] Development performance in durability testing

[0374] Image density was measured relative to an image with an image density of 0.00 against a white background using a "Macbeth Densitometer RD918" (manufactured by Macbeth Co., Ltd.) according to the instruction manual provided with the device, and the obtained relative density was used as the image density value. Development performance in the durability test was determined by the degree of density reduction. The degree of density reduction was evaluated based on the following criteria regarding the difference between the initial density and the density after the durability test, wherein the average center density of each of the three images output in (1) was taken as the initial density, and the average center density of each of the three images output in (5) was taken as the density after the durability test. An evaluation of C or higher corresponds to an acceptable level.

[0375] A: Less than 0.05.

[0376] B: 0.05 or higher and less than 0.1.

[0377] C: 0.1 or higher and less than 0.15.

[0378] D: 0.15 or higher and less than 0.20.

[0379] E: 0.20 or more.

[0380] Examples 2 to 15

[0381] The same evaluations as in Example 1 were performed using toners 1 through 15. The evaluation results are shown in Table 3.

[0382] Comparative Examples 1 to 5

[0383] The same evaluations as in Example 1 were performed using comparative toners 1 through 5. The evaluation results are shown in Table 3.

[0384] [Table 3]

[0385]

[0386] In Table 3, “CE” represents “Comparative Example” and “CT” represents “Comparative Toner”.

[0387] While the invention has been described with reference to exemplary embodiments, it will be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the appended claims should be accorded the broadest interpretation to cover all such variations and equivalent structures and functions.

Claims

1. A toner, characterized in that, It includes colorant particles containing binder resin and boric acid. The toner has an average roundness of 0.95 or higher. In the fluorescence X-ray measurement of the toner particles, the intensity of boron was 0.1 to 0.6 kcps, and The toner satisfies the following conditions (a) and (b): (a) The shape factor SF1 of the toner is 105 to 125, and (b) The shape factor SF1 of the cross section of the toner formed by the cross section polishing method, i.e., the CP cross section method, is 105 to 125.

2. The toner according to claim 1, wherein boric acid is detected in the IR analysis of the toner particles by the ATR method using germanium as an ATR crystal.

3. The toner according to claim 1 or 2, wherein... When toner is sieved for 10 seconds using a 22-μm open sieve, it falls from a height of 10 cm onto a horizontal glass plate. The total contact area between 50 toner particles and the glass plate is defined as the contact area D, and the total projected area of ​​the 50 toner particles is defined as S. The ratio D / S is 3 to 14%.

4. The toner according to claim 1 or 2, wherein The colorant also contains external additives. The external additive contains silica particles, and The surface area of ​​the toner particles covered by the silica microparticles, as measured by an X-ray photoelectron spectroscopy device, is 50 to 80% of the area.

5. The toner according to claim 4, wherein the dispersion evaluation index of the silica particles on the surface of the toner is 0.10 to 2.

00.

6. A method for manufacturing a toner according to any one of claims 1 to 5, characterized in that, The method for manufacturing the toner comprises the following steps (1) to (3) in the following order: (1) Dispersion step: preparing a dispersion of binder resin particles containing the binder resin. (2) An aggregation step, wherein the binder resin particles contained in the binder resin particle dispersion are aggregated to form aggregates, and (3) The fusion step involves heating and fusing the aggregate, and A boric acid source is added in at least one of the aggregation step and the fusion step.

7. The method for manufacturing a toner according to claim 6, wherein the aggregation step comprises the steps (2-1) and (2-2): (2-1) The aggregation step of agglomerating the binder resin particles contained in the binder resin particle dispersion to form aggregates, and (2-2) A shell-forming step in which resin particles containing shell resin are further added to a dispersion of binder resin particles containing aggregates and the resin particles containing shell resin are aggregated to form aggregates having shells.

8. The method of manufacturing a toner according to claim 6, wherein the method of manufacturing the toner comprises the following steps (4) to (6) performed in the following order during or after the fusion step: (4) Spheroidization step, which involves further heating the aggregates at an increased temperature. (5) Cooling step: cooling the aggregate at a cooling rate of 0.1°C / second or higher, and (6) Annealing step, wherein the aggregate is heated and held at a temperature equal to or higher than the crystallization temperature or glass transition temperature of the binder resin.

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