Two-component developer

Abstract

To provide a positively charged two-component developer that can achieve both excellent durability and fast charge rise. [Solution] A two-component developer comprising a positively charged toner and a carrier, wherein (i) the carrier comprises carrier core particles and a resin coating layer covering the surface of the carrier core particles, the resin coating layer containing a silicone resin, and (ii) the amount of silanol groups on the surface of the carrier, as measured by titration using KOH, is 4.00 × 10 -6 mol / g or more 4.00×10 -4 A two-component developer characterized by having a charge of mol / g or less, wherein the positively charged toner comprises toner particles and external additive particles, and the external additive particles include alumina particles.

Description

[Technical Field]

[0001] This disclosure relates to a two-component developer used in an electrophotographic image forming method. [Background technology]

[0002] Conventionally, electrophotographic image formation methods generally involve forming an electrostatic latent image on an electrostatic latent image carrier using various means, and then developing the electrostatic latent image by attaching toner to it. In this development process, a two-component development method is widely employed, in which carrier particles called magnetic carrier particles are mixed with the toner, triboelectrically charged to impart an appropriate amount of positive or negative charge to the toner, and this charge is used as a driving force for development. In this case, the magnetic carrier particles often have a core that is magnetized to acquire transportability, and a coating layer made of a coating resin that is coated on the core to acquire the ability to impart charge to the toner.

[0003] In recent years, technological advancements in the field of electrophotography have led to a higher demand for longer lifespan in image forming apparatuses. This requires that toner and carriers undergo minimal changes in their state even during long-term use, maintaining stable image quality. Therefore, from the perspective of improving durability, carriers using silicone resin in the coating layer are known (Patent Documents 1 and 2). Furthermore, positively charged toners, which have a specific compound with positive charge properties added to improve image quality stability, are also known (Patent Document 3). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 6-118725 [Patent Document 2] Japanese Patent Application Publication No. 8-272147 [Patent Document 3] Japanese Patent Publication No. 2016-139039 [Overview of the project]

Problems to be Solved by the Invention

[0005] When a carrier coated with a silicone resin is used in a negatively charged developer as in Patent Documents 1 and 2, since the silicone resin has sufficient charge imparting properties, the charge rising property is good. On the other hand, when a carrier coated with a silicone resin is used in a positively charged developer as in Patent Document 3, the charge rising property may be insufficient, and particularly in a low humidity environment or a high temperature and high humidity environment, the charge rising property may decrease.

[0006] At least one aspect of the present disclosure provides a two-component developer capable of solving the above problems. Specifically, a positively charged two-component developer capable of achieving both excellent durability and charge rising property is provided.

Means for Solving the Problems

[0007] At least one aspect of the present disclosure is a two-component developer including a positively charged toner and a carrier, (i) the carrier has carrier core particles and a resin coat layer covering the surface of the carrier core particles, and the resin coat layer contains a silicone resin, (ii) the amount of silanol groups on the carrier surface measured by a titration method using KOH is 4.00×10 -4 , mol / g or more and 4.00×10 -4 mol / g or less, <00001​​​​​​​​​​​​​​​​​ In this disclosure, descriptions of numerical ranges such as "XX or greater and YY or less" or "XX to YY" mean a numerical range that includes the lower and upper limits, unless otherwise specified. When numerical ranges are described in steps, the upper and lower limits of each numerical range can be any combination. In addition, in this disclosure, a description such as "at least one selected from the group consisting of XX, YY, and ZZ" means any of the following: XX, YY, ZZ, a combination of XX and YY, a combination of XX and ZZ, a combination of YY and ZZ, or a combination of XX, YY, and ZZ. Furthermore, a monomer unit refers to the reacted form of monomer substances within a polymer.

[0010] The inventors believe the mechanism by which the effects of this disclosure manifest themselves is as follows: Silicone resins, commonly used as carrier coating resins, possess elasticity and low surface energy, which provides functions such as strengthening the coating layer, improving stain resistance, and reducing damage to toner, thus effectively improving the durability of two-component developers. However, it has become clear that when silicone resin is used as the carrier coating resin for positively charged developers, the low negative charge properties of silicone resin tend to lead to a decrease in the toner's charge rise time.

[0011] On the other hand, the carrier contained in the two-component developer of this disclosure has a surface coated with a resin coating layer containing a silicone resin, and the amount of silanol groups on the carrier surface is 4.00 × 10 -6 mol / g or more 4.00×10 -4 The concentration is mol / g or less. In other words, a large number of silanol groups are present in the resin coating layer on the carrier surface. Furthermore, the two-component developer contains a positively charged toner, and this positively charged toner contains alumina particles as an external additive.

[0012] The presence of many silanol groups in the resin coating layer on the carrier surface increases the negative charge of the carrier. Furthermore, acid-base interactions between the acidic silanol groups and the basic alumina present on the surface of the toner particles improve the charge build-up speed, allowing for sufficient charge build-up even in low-humidity or high-temperature, high-humidity environments. In other words, by adopting the above configuration, a two-component developer that achieves both excellent durability and charge build-up speed can be obtained.

[0013] The two-component developer of this disclosure is a two-component developer comprising a positively charged toner and a carrier, (i) The carrier comprises carrier core particles and a resin coating layer covering the surface of the carrier core particles, wherein the resin coating layer contains a silicone resin. (ii) The amount of silanol groups on the carrier surface, as measured by titration using KOH, is 4.00 × 10⁻⁶. -6 mol / g or more 4.00×10 -4 It is less than or equal to mol / g. The positively charged toner comprises toner particles and external additive particles. The external additive particles include alumina particles. It is characterized by the following: The following provides a detailed description of each component that makes up a two-component developer.

[0014] <Career> The carrier comprises carrier core particles and a resin coating layer covering the surface of the carrier core particles. The resin coating layer contains silicone resin. That is, the carrier is a carrier It has a silicone resin coating layer on the surface of the acore particles and carrier core particles. The carrier core particles are not particularly limited, and ordinary magnetic carriers such as ferrite and magnetite can be used. For example, it is preferable to use a MnMg ferrite core as the carrier core particle.

[0015] The amount of silanol groups on the carrier surface, measured by titration using KOH, is 4.00 × 10⁻⁶. -64.00×10 or more mol / g -4 It is 4.00×10 mol / g or less. The amount of the silanol groups on the carrier surface is 4.00×10 -6 4.00×10 or more mol / g -4 When the amount of the silanol groups is 4.00×10 or more mol / g, a large number of silanol groups are present on the surface, improving the negative charge property of the carrier and resulting in good charge rising property. Also, the amount of charge hardly decreases even after being left for a long time in a high temperature and high humidity environment, and a carrier excellent in charge retention property can be obtained.

[0016] When the amount of the silanol groups on the carrier surface is 4 or more.00×10 -6 mol / g, the negative charge property of the carrier is improved, so that the charge rising property of the toner can be improved. Also, when the amount of the silanol groups is 4.00×10 -4 mol / g or less, it is possible to suppress the excessive increase in the hydrophilicity of the carrier surface. As a result, it is difficult to absorb moisture even in a high humidity environment, preventing charge leakage and improving charge retention property.

[0017] The amount of the silanol groups is preferably 4.50×10 -6 mol / g or more, more preferably 5.00×10 -6 mol / g or more, still more preferably 7.00×10 -6 mol / g or more. Also, it is preferably 4.00×10 -5 mol / g or less, more preferably 3.00×10 -5 mol / g or less, still more preferably 2.00×10 -5 mol / g or less. That is, the amount of the silanol groups is preferably 4.50×10 -6 mol / g or more and 4.00×10 -5 mol / g or less, more preferably 5.00×10 -6 mol / g or more and 3.00×10 -5 mol / g or less, still more preferably 7.00×10 -6 mol / g or more and 2.00×10 -5It is even more preferable that the amount is mol / g or less. A method for adjusting the amount of silanol groups on the carrier surface will be described later.

[0018] The resin coating layer contains silicone resin. The silicone resin preferably has monomer units represented by the following formulas (a) and (b). Furthermore, it is more preferable that the structure of the silicone resin, excluding the ends (main skeleton), is composed solely of monomer units represented by the following formulas (a) and (b). [ka] (R 1 , R 2 Each of these independently represents an alkyl group with 1 to 6 carbon atoms. When the silicone resin is composed solely of monomer units represented by formulas (a) and (b) above, the O in the monomer units represented by formulas (a) and (b) is replaced by the Si in the formulas above. a or Si c They combine.

[0019] The monomer unit shown in formula (a) above is derived from a tetrafunctional silane, and the monomer unit shown in formula (b) above is derived from a difunctional silane. In other words, the silicone resin is preferably a condensed polymer of a tetrafunctional silane monomer and a difunctional silane monomer. When the silicone resin is composed of the two monomer units shown in formulas (a) and (b) above, the crosslinking density does not become excessively high, so the resin coating layer has appropriate elasticity. Therefore, when the toner and carrier come into contact, the damage to the toner is reduced, and the durability as a two-component developer is further improved.

[0020] The monomers used in the synthesis of silicone resins can be appropriately selected based on their compatibility with the solvent and catalyst, as well as their hydrolysis properties. Examples of tetrafunctional silane monomers that can be used as raw materials for the above structure (a) include tetramethoxysilane, tetraethoxysilane, and tetraisocyanatesilane, but tetraethoxysilane is preferred among these. Examples of difunctional silane monomers that can be used as raw materials for the above-mentioned structure (b) include di-tert-butyldichlorosilane, di-tert-butyldimethoxysilane, di-tert-butyldiethoxysilane, dibutyldichlorosilane, dibutyldimethoxysilane, dibutyldiethoxysilane, dichlorodimethylsilane, dimethyldimethoxysilane, diethoxydimethylsilane, and diethyldimethoxysilane, but dimethyldimethoxysilane is preferred among these.

[0021] <Carrier manufacturing method> The carrier can be manufactured by coating the surface of the carrier core particles with a silicone resin. The following describes the carrier manufacturing method in detail.

[0022] The method for coating the carrier with silicone resin is not particularly limited and any known method may be used. It is possible. For example, a preferred method involves forming an oligomer solution by hydrolysis of a silicon compound and a condensation polymerization reaction of the hydrolyzed product, coating the surface of the carrier core particles with this solution, and then heating it at a high temperature.

[0023] In the above-described method, it is preferable to use a mixture containing a bifunctional silane and a tetrafunctional silane as the silicon compound. Specifically, a mixture of a bifunctional silane having two siloxane bonds and a tetrafunctional silane having four siloxane bonds is hydrolyzed, and the resulting hydrolysate is polymerized to form an oligomer. Subsequently, a solution of the obtained oligomer is coated onto the surface of carrier core particles, and cured by further heating on the surface of the carrier core particles to form a resin coating layer containing a silicone resin. The silane monomers described above can be used as the bifunctional silane and the tetrafunctional silane, respectively.

[0024] The amount of silanol groups in the resin coating layer can be adjusted by adjusting the ratio of difunctional silanes and tetrafunctional silanes in the above mixture. Since the resin coating layer is formed on the surface of the carrier core particles, the amount of silanol groups on the carrier surface can be controlled to a specific range by the above method.

[0025] Specifically, increasing the proportion of tetrafunctional silanes in the mixture can increase the amount of silanol groups on the carrier surface. Conversely, increasing the proportion of bifunctional silanes in the mixture can decrease the amount of silanol groups on the carrier surface. The content of bifunctional silanes in the mixture is preferably 30 to 70 mol%, and more preferably 40 to 60 mol%. Furthermore, the content of tetrafunctional silanes in the mixture is preferably 30 to 80 mol%, and more preferably 40 to 60 mol%. In the mixture, the molar ratio of difunctional silane to tetrafunctional silane (the value of molar amount of difunctional silane / molar amount of tetrafunctional silane) is preferably 0.3 to 2.3, and more preferably 0.5 to 1.5.

[0026] A carrier having a resin coating layer containing silicone resin is preferably manufactured by the following method. Specifically, it is preferable to include: (1) a first step of obtaining a hydrolysate of a silicon compound; (2) a second step of undergoing a polycondensation reaction of the hydrolysate to obtain an oligomer of the hydrolysate; (3) a third step of coating the surface of carrier core particles with a solution containing the oligomer; and (4) a fourth step of heating the coated carrier core particles to form a resin coating layer by polycondensing the oligomer.

[0027] (First step) The first step is to obtain the hydrolysate of the silicon compound. In an aqueous solution in which an acidic or alkaline catalyst is dissolved in water, the silicon compound and the catalyst are brought into contact by stirring, mixing, or other means to obtain the hydrolysate of the silicon compound. As the silicon compound, a mixture of the aforementioned bifunctional silane and tetrafunctional silane can be used.

[0028] Any known catalyst can be suitably used as the catalyst. Specifically, examples of acidic catalysts include acetic acid, hydrochloric acid, hydrofluoric acid, sulfuric acid, and nitric acid, while examples of basic catalysts include aqueous ammonia, sodium hydroxide, and potassium hydroxide. The amount of catalyst used can be adjusted as appropriate depending on the type of silicon compound and catalyst. For example, when using the above-mentioned bifunctional silane and tetrafunctional silane as the silicon compound and acetic acid as the catalyst, the catalyst content in the aqueous solution is 1 × 10⁻⁶ parts per 100 parts by mass of water. -3 mass Preferably, the amount is between 1 part by mass and more.

[0029] The catalyst content in the aqueous solution is 1 × 10 -3 If the catalyst content is 1 part by mass or more, the hydrolysis reaction of silicon compounds will proceed sufficiently. Furthermore, if the catalyst content is 1 part by mass or less, the catalyst is less likely to remain as an impurity in the aqueous solution, making it easier for the hydrolysis reaction to proceed. When preparing the aqueous solution, the amount of water used is preferably between 2 moles and 15 moles per mole of silicon compound. If the amount of water is 2 moles or more, the hydrolysis reaction proceeds sufficiently, while if it is 15 moles or less, productivity is improved.

[0030] The reaction temperature for hydrolysis is not particularly limited and can be carried out at room temperature or under heating. It is preferable to carry out the hydrolysis reaction while maintaining the temperature at 10 to 60°C, as this allows for the acquisition of hydrolysates in a shorter time and suppresses the partial condensation reaction of the resulting hydrolysates. The reaction time is not particularly limited and can be appropriately selected considering the reactivity of the silicon compound used, the composition of the aqueous solution containing the silicon compound, catalyst, and water, and the productivity. For example, the reaction time for hydrolysis may be 1 to 20 minutes or 3 to 10 minutes.

[0031] (Second step) The second step involves polycondensing the hydrolysate obtained in the first step to obtain an oligomer of the hydrolysate. Specifically, the above hydrolysate is mixed with an alkaline aqueous medium to cause a polycondensation reaction of the hydrolysate. This yields a solution of oligomers, which are the polycondensation products of the hydrolysate.

[0032] Here, an alkaline aqueous medium is an aqueous medium obtained by mixing an alkaline component, water, and, if necessary, an organic solvent. The alkaline components used in alkaline aqueous media are those whose aqueous solutions exhibit basic properties. These alkaline components act as a neutralizing agent for the catalyst used in the first step and as a catalyst for the polycondensation reaction in the second step.

[0033] Examples of such alkaline components include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide; ammonia; and organic amines such as monomethylamine and dimethylamine. The amount of alkaline component used should be sufficient to neutralize the acid and act effectively as a catalyst for the polycondensation reaction, and can be adjusted as appropriate depending on the type of alkaline component and acid used. For example, when ammonia is used as the alkaline component, it is preferable that the content of the alkaline component is between 0.01 parts by mass and 12.5 parts by mass per 100 parts by mass of the mixture of water and organic solvent.

[0034] In the second step, an organic solvent may be used in addition to the alkaline component and water to prepare an alkaline aqueous medium. The organic solvent is not particularly limited as long as it is miscible with water, but an organic solvent that dissolves 10 g or more of water per 100 g at room temperature and atmospheric pressure is preferred. Specifically, examples include alcohols such as methanol, ethanol, n-propanol, 2-propanol, and butanol; polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, glycerin, trimethylolpropane, and hexanetriol; ethers such as ethylene glycol monoethyl ether, acetone, diethyl ether, tetrahydrofuran, and diacetone alcohol; and amide compounds such as dimethylformamide, dimethylacetamide, and N-methylpyrrolidone.

[0035] Among the organic solvents listed above, methanol, ethanol, 2-propanol, and butano Alcohol-based solvents such as alcohol are preferred. Furthermore, from the viewpoint of hydrolysis and dehydration condensation reactions, it is even more preferable to select the same alcohol as the alcohol produced by elimination as the organic solvent.

[0036] While the reaction temperature and time for the polycondensation reaction are not particularly limited, if the reaction temperature is too high or the reaction time is too long, the condensation reaction will proceed too far, causing gelation and making it difficult to coat the surface of the carrier core particles. From this viewpoint, it is preferable to carry out the reaction for 1 to 4 hours while maintaining the temperature at 10 to 50°C.

[0037] (Third step) The third step is to coat the surface of the carrier core particles with the oligomer-containing solution obtained in the second step. The silicone oligomer solution obtained in the second step is coated onto the surface of the carrier core particles using a known method such as a rolling fluidized bed coating apparatus. For example, a method of spraying the oligomer solution onto the surface of the carrier core particles using the above-mentioned coating apparatus can be used.

[0038] The thickness of the formed resin coating layer can be adjusted by adjusting the amount of oligomer solution relative to the amount of carrier core particles. The thickness of the resin coating layer is not particularly limited, but it is preferably a thickness that can suppress the exposure of the carrier core particles. In order to form a coating layer having the above thickness, the amount of oligomer solution used for coating is preferably 0.5 parts by mass or more and 10.0 parts by mass or less per 100 parts by mass of carrier core particles.

[0039] (Fourth step) The fourth step involves heating the carrier core particles coated in the third step and forming a resin coating layer by polycondensing the oligomer. First, the solution containing the oligomer coated on the surface of the carrier core particles is heated and dried to remove the solvent from the reaction solution. The temperature and time for drying are not particularly limited as long as the temperature can remove the solvent, but it is preferable to dry at a temperature of 70°C to 90°C for 30 minutes to 2 hours.

[0040] Next, the dried particles are heated at a high temperature using an electric furnace to cause polycondensation of the oligomers contained in the solution. This reaction hardens the coating resin on the surface of the carrier core particles, forming a resin coating layer containing silicone resin. The temperature and time for hardening are not particularly limited as long as the temperature is suitable for hardening the silicone resin, but it is preferable to harden it at a temperature of 200°C to 300°C for 1 to 3 hours, for example.

[0041] It is preferable that the proportion of carbon atoms bonded to silicon atoms relative to the total amount of carbon atoms, oxygen atoms, and silicon atoms, as measured by X-ray photoelectron spectroscopy (ESCA) of carriers, is 30 atm% or more. X-ray photoelectron spectroscopy (ESCA) allows for qualitative and quantitative analysis of elements present on the carrier surface (a few nanometers). A ratio of 30 atm% or higher for carbon atoms bonded to silicon atoms relative to the total amount of carbon, oxygen, and silicon atoms measured by ESCA indicates a high proportion of carbon atoms bonded to silicon atoms on and near the carrier surface. When the ratio of carbon atoms bonded to silicon atoms to the total amount of carbon, oxygen, and silicon atoms on and near the surface of a carrier is 30 atm% or more, the hydrophobicity of the carrier increases, resulting in good charge retention even in high-temperature and high-humidity environments.

[0042] From the above viewpoint, the proportion of carbon atoms is more preferably 35 atm% or more, and even more preferably 40 atm% or more. There is no particular upper limit, but it is usually 60 atm. It is less than or equal to %. The ratio of carbon atoms bonded to silicon atoms to the total amount of carbon atoms, oxygen atoms, and silicon atoms present near the surface of the carrier is preferably 30 to 60 atm%, more preferably 35 to 60 atm%, and even more preferably 35 to 50 atm%.

[0043] The proportion of carbon atoms mentioned above can be adjusted by the charging ratio of difunctional silanes to tetrafunctional silanes. To increase the proportion of carbon atoms, increase the proportion of difunctional silanes; to decrease the proportion of carbon atoms, increase the proportion of tetrafunctional silanes. In a mixture of silicon compounds used for hydrolysis, the mass ratio of difunctional silane to tetrafunctional silane (the value of the mass of difunctional silane / the mass of tetrafunctional silane) is preferably 0.3 to 2.0, more preferably 0.5 to 1.5, and even more preferably 0.7 to 1.4.

[0044] The resin coating layer may be formed as a single layer or may consist of multiple layers. The resin coating layer is preferably composed of a single layer. That is, it is preferable that only one layer of resin coating containing silicone resin is formed on the surface of the carrier core particles. By covering the carrier surface with a resin coating layer containing a soft silicone resin, the impact is absorbed when it collides with the toner in the developing unit, thereby suppressing changes in the toner's durability. On the other hand, if there is a layer of hard resin, such as fluororesin or acrylic resin, beneath the silicone resin, the impact-absorbing effect may not be fully realized. Therefore, it is preferable that the resin coating layer be composed of a single layer containing silicone resin.

[0045] When forming multiple resin coating layers, the outermost resin coating layer may contain silicone resin. For example, a resin coating layer containing fluororesin or acrylic resin can be formed in advance on the surface of carrier core particles, and a coating layer containing silicone resin can be formed on the surface of the resin coating layer. That is, beneath the resin coating layer containing silicone resin, there may be one or more resin coating layers, and the resin coating layer may contain resins other than silicone resin.

[0046] The resin coating layer preferably contains barium titanate particles. The inclusion of barium titanate, which has a high dielectric constant, in the carrier's resin coating layer increases the capacitance of the carrier itself, improving its charge-inducing ability and thus its charge-starting performance. Furthermore, the inclusion of strong barium titanate in the resin coating layer helps to prevent the soft silicone resin coating layer from peeling off the carrier when subjected to stress in the developing unit.

[0047] For example, in the first step of the above-described method for manufacturing a resin coating layer, a resin coating layer containing barium titanate particles can be formed by adding barium titanate particles to an aqueous solution containing a silicon compound. The barium titanate is not particularly limited and commercially available barium titanate can be used. The particle size of the barium titanate is not particularly limited and, for example, a particle size of 50 to 150 nm can be used. The content of barium titanate is not particularly limited and, for example, it is preferable to contain 1 to 5 parts by mass per 100 parts by mass of the above-mentioned silicon compound mixture.

[0048] <Toner> A two-component developer contains a positively charged toner. The positively charged toner has toner particles and external additive particles. The external additive particles include alumina particles.

[0049] <Alumina particles> The toner contains alumina particles as an external additive. The method for producing the alumina particles is not particularly limited. It can also be manufactured by known methods. For example, it can be manufactured by crushing the raw material alumina and then calcining it.

[0050] It is preferable that the alumina particle content per 100 parts by mass of toner particles is 0.1 to 10.0 parts by mass. When the amount of alumina particles relative to toner particles is within the above range, the silanol groups on the carrier surface and the alumina on the toner particle surface come into appropriate contact, and the acid-base interaction between the acidity of the silanol groups and the basicity of the alumina particles improves the charging response. From the above viewpoint, the content of alumina particles per 100 parts by mass of toner particles is more preferably 0.5 to 5.0 parts by mass, and even more preferably 0.7 to 3.0 parts by mass.

[0051] The alumina particles preferably have an average circularity of 0.950 or less. The low circularity of the alumina particles, and their non-spherical, spherical shape, suppresses their rolling on the surface of the toner particles and their flow into the grooves of the toner particles. This allows for easier contact between the carrier and the alumina particles, improving the charge build-up performance through acid-base interactions with the silanol groups on the carrier surface. From the above viewpoint, an average circularity of 0.900 or less is more preferable for the alumina particles, and even more preferable is 0.850 or less. The average circularity of alumina particles can be adjusted by changing the grinding time of the alumina raw material.

[0052] It is preferable that the alumina particles have a conductive layer containing tin on their surface. The method for coating the surface of alumina particles with a conductive layer containing tin is not particularly limited, but for example, the following method can be used.

[0053] A slurry is obtained by dispersing alumina particle substrates in an aqueous medium. A solution containing a tin compound (e.g., tin chloride pentahydrate) and aqueous ammonia are added dropwise to the obtained slurry while adjusting the pH. After filtering and washing the slurry, it is calcined to coat the surface of the alumina particles with a conductive layer containing tin. When the surface of alumina is coated with a conductive layer containing tin, the conductivity of tin promotes the transfer of charge to the toner, thereby improving the charge rise time.

[0054] In the EDS analysis of the above alumina particles, when x is the weight percentage of Al and y is the weight percentage of Sn, it is preferable that x / y is between 1.0 and 1.7. A value of x / y between 1.0 and 1.7 indicates that the surface of the alumina particles is coated with a conductive layer containing a moderate amount of tin. As a result, the charge rise time can be further improved. A value of x / y between 1.1 and 1.5 is more preferable from the above viewpoint, and a value of 1.1 to 1.3 is even more preferable. The x / y ratio can be adjusted by the amount of tin-containing compound used when coating the alumina substrate. For example, by coating 100 parts by mass of alumina substrate with 10 to 30 parts by mass of tin-containing compound, the x / y value can be controlled to the above range.

[0055] <Toner particles> The toner particles contain a binder resin. In addition to the binder resin, the toner particles may also contain colorants, release agents, charge control agents, etc.

[0056] (Binding resin) Any known binder resin can be used. For example, the following are examples of binder resins: Styrene resins, styrene copolymer resins, polyester resins, polyol resins, polyvinyl chloride resins, phenolic resins, naturally modified phenolic resins, naturally modified maleic acid Resins, acrylic resins, methacrylic resins, polyvinyl acetate, silicone resins, polyurethane resins, polyamide resins, furan resins, epoxy resins, xylene resins, polyvinyl butyral, terpene resins, coumarone indene resins, petroleum-based resins.

[0057] Preferred resins include styrene copolymer resins, polyester resins, and hybrid resins obtained by mixing a polyester resin and a styrene copolymer resin or by a partial reaction between the two. More preferably, the binder resin includes a polyester resin. The polyester resin is not particularly limited, and known resins used in toners can be used.

[0058] (Coloring agent) As colorants, known ones can be used. For example, the following can be used: Examples of black colorants include carbon black and black colorants prepared by mixing yellow, magenta, and cyan colorants. While pigments may be used alone as colorants, using dyes and pigments in combination is preferable from the standpoint of full-color image quality to improve clarity.

[0059] The following are examples of pigments used for magenta toner: CI Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 39, 40, 41, 48:2, 48:3, 48:4, 49, 50, 51, 52, 53, 54, 55, 57:1, 58, 60, 63, 64, 68, 81:1, 83, 87, 88, 89, 90, 112, 114, 122, 123, 146, 147, 150, 163, 184, 202, 206, 207, 209, 238, 269, 282; CI Pigment Violet 19; CI Bat Red 1, 2, 10, 13, 15, 23, 29, 35.

[0060] Examples of dyes for magenta toner include: oil-soluble dyes such as CI Solvent Red 1, 3, 8, 23, 24, 25, 27, 30, 49, 81, 82, 83, 84, 100, 109, 121; CI Disperse Red 9; CI Solvent Violet 8, 13, 14, 21, 27; CI Disperse Violet 1; and basic dyes such as CI Basic Red 1, 2, 9, 12, 13, 14, 15, 17, 18, 22, 23, 24, 27, 29, 32, 34, 35, 36, 37, 38, 39, 40; and CI Basic Violet 1, 3, 7, 10, 14, 15, 21, 25, 26, 27, 28.

[0061] Examples of pigments for cyan toner include: CI Pigment Blue 2, 3, 15:2, 15:3, 15:4, 16, 17; CI Bat Blue 6; CI Acid Blue 45; and copper phthalocyanine pigments in which phthalimidomethyl groups are substituted onto the phthalocyanine skeleton. CI Solvent Blue 70 is a dye used for cyan toner.

[0062] The following pigments are used for yellow toner: CI Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 15, 16, 17, 23, 62, 65, 73, 74, 83, 93, 94, 95, 97, 109, 110, 111, 120, 127, 128, 129, 147, 151, 154, 155, 168, 174, 175, 176, 180, 181, 185; CI Bat Yellow 1, 3, 20. CI Solvent Yellow 162 is a dye used for yellow toner.

[0063] The coloring agent content is preferably 0.1 parts by mass or more and 30.0 parts by mass or less per 100 parts by mass of the binder resin.

[0064] (Release agent) Wax may be used in the toner particles as needed. Examples of waxes include the following: Hydrocarbon waxes such as microcrystalline wax, paraffin wax, and Fischer-Tropsch wax; oxides of hydrocarbon waxes such as oxidized polyethylene wax or block copolymers thereof; waxes mainly composed of fatty acid esters such as carnauba wax; and deoxidized fatty acid esters such as deoxidized carnauba wax, which have been partially or completely deoxidized.

[0065] Furthermore, the following can be listed: saturated linear fatty acids such as palmitic acid, stearic acid, and montanic acid; unsaturated fatty acids such as brassic acid, eleostearic acid, and valinalic acid; saturated alcohols such as stearyl alcohol, aralkyl alcohol, behenyl alcohol, carnaubyl alcohol, ceryl alcohol, and melissyl alcohol; polyhydric alcohols such as sorbitol; esters of fatty acids such as palmitic acid, stearic acid, behenic acid, and montanic acid with alcohols such as stearyl alcohol, aralkyl alcohol, behenyl alcohol, carnaubyl alcohol, ceryl alcohol, and melissyl alcohol; fatty acid amides such as linoleic acid amide, oleic acid amide, and lauric acid amide; methylenebisstearate amide, ethylenebiscaprate amide, ethylenebislaurate amide, and hexamethylene Saturated fatty acid bisamides such as bis-stearamide; unsaturated fatty acid amides such as ethylenebisoleamide, hexamethylenebisoleamide, N,N'dioleyladipamide, and N,N'dioleylsebacamide; aromatic bisamides such as m-xylenebis-stearamide and N,N'distearylisophthalamide; aliphatic metal salts (commonly known as metal soaps) such as calcium stearate, calcium laurate, zinc stearate, and magnesium stearate; waxes grafted onto aliphatic hydrocarbon waxes with vinyl monomers such as styrene or acrylic acid; partially esterified fatty acids and polyhydric alcohols such as behenic acid monoglyceride; and methyl ester compounds having hydroxyl groups obtained by hydrogenation of vegetable oils. The wax content is preferably 2.0 parts by mass or more and 30.0 parts by mass or less per 100 parts by mass of the binder resin.

[0066] (Charge control agent) Toner particles preferably contain a charge control agent. While known charge control agents can be used, the following are preferred, for example: Examples of positive charge control agents include quaternary ammonium salts, polymeric compounds having the quaternary ammonium salt as a side chain, guanidine compounds, and imidazole compounds.

[0067] Toner particles preferably contain a quaternary ammonium salt as a charge control agent. By containing a positively charged quaternary ammonium salt in the toner particles, the positive charge of the toner itself can be enhanced through contact with the silanol groups on the carrier surface.

[0068] The amount of charge control agent is preferably 0.1 parts by mass or more and 10.0 parts by mass or less per 100.0 parts by mass of the binder resin. Examples of quaternary ammonium salts include benzyldecylhexylmethylammonium chloride, decyltrimethylammonium chloride, 2-(methacryloyloxy)ethyltrimethylammonium chloride, and dimethylaminopropylacrylamide methyl quaternary salt.

[0069] (External additive) Toner particles preferably contain silica particles in addition to the alumina particles mentioned above as an external additive. Because silica particles have a high affinity for the silanol groups on the carrier surface, including silica particles in the external additive allows for more efficient contact with the carrier particles, thereby promoting triboelectric charging. As a result, the charging response can be further improved. The silica particle content per 100 parts by mass of toner particles is preferably 0.1 to 10.0 parts by mass.

[0070] Examples of silica particles include particles composed of silicon dioxide, such as wet silica obtained by sedimentation or sol-gel methods, and dry silica obtained by deflagration or fumed methods. Dry silica is more preferable due to its ease of shape control. Dry silica is produced using silicon halogen compounds as raw materials. Silicon tetrachloride is used as the silicon halogen compound, but silanes such as methyltrichlorosilane and trichlorosilane can also be used as raw materials, either alone or in a mixture of silicon tetrachloride and silanes.

[0071] After vaporizing the above raw materials, the desired dry silica can be obtained by a so-called flame hydrolysis reaction, in which the raw materials react with water, which is produced as an intermediate in an oxyhydrogen flame. The above flame hydrolysis reaction utilizes, for example, the thermal decomposition oxidation reaction of silicon tetrachloride gas in oxygen and hydrogen, and is represented by the following reaction equation. SiCl₄ + 2H₂ + O₂ → SiO₂ + 4HCl

[0072] The following describes an example of dry silica production using the above reaction. Oxygen gas is supplied to a burner, and after ignition, hydrogen gas is supplied to the burner to form a flame. Silicon tetrachloride, the raw material, is then added to this flame and gasified to carry out a flame hydrolysis reaction. After that, the resulting silica powder is recovered. The average particle size and shape of the dry silica can be adjusted by appropriately changing the silicon tetrachloride flow rate, oxygen gas supply flow rate, hydrogen gas supply flow rate, and silica residence time in the flame during the above reaction. The number-average particle size of the dry silica is not particularly limited, but is preferably, for example, 10 to 50 nm.

[0073] It is preferable that the silica particles are surface-treated with a treatment agent containing amino groups. As mentioned above, silica particles have a high affinity for the silanol groups on the carrier surface, and can efficiently achieve triboelectric charging with the carrier particles. Furthermore, since silica with amino groups on its surface is positively charged, adding silica with amino groups to the surface of toner particles increases the positive charge of the toner. Therefore, surface-treated silica particles with an amino group treatment agent can further improve the charge build-up performance.

[0074] Examples of treatment agents having an amino group include, for example, 3-aminopropyltrialkoxysilane, 3-(2-aminoethylamino)propyltrialkoxysilane, and 3-(2-aminoethylamino)propyldialkoxymethylsilane. For example, it is preferable to use 3-aminopropyltriethoxysilane. The surface treatment method for silica particles is not particularly limited, but for example, the surface treatment can be performed by heating a silica particle substrate, such as fumed silica, in a reaction vessel, and then supplying vapor of a treatment agent having amino groups while heating and stirring.

[0075] In addition to the alumina and silica particles mentioned above, other external additives can be used in combination as needed to improve electrostatic stability, developability, fluidity, and durability of the toner particles. Specific examples of suitable external additives include metal oxides such as titanium dioxide, magnesium oxide, zinc oxide, strontium titanate, and barium titanate, as well as resin microparticles.

[0076] As an external additive for improving fluidity, it has a specific surface area of ​​50 m². 2 / g or more 400m 2 Fine particles of less than / g are preferred. To achieve both improved fluidity and stable durability, multiple fine particles with a specific surface area within the above range may be used in combination. The above-mentioned external additive is preferably used in an amount of 0.1 parts by mass or more and 10.0 parts by mass or less per 100 parts by mass of toner particles. When multiple external additives are used, it is preferable that the total amount of all external additives is within the above range. Meeting the above range makes it easier to obtain the effect of durability and stability.

[0077] <Two-component developer> The two-component developer contains a positively charged toner and a carrier. The mixing ratio of positively charged toner and carrier contained in the two-component developer is preferably such that the mass of toner relative to the mass of the two-component developer is 2% by mass or more and 15% by mass or less, more preferably 4% by mass or more and 13% by mass or less. By mixing in the above ratio, a two-component developer with excellent durability and charge rise time can be obtained.

[0078] When the alumina content per 100g of the two-component developer is Amol and the amount of silanol groups on the carrier surface per 100g of the two-component developer is Bmol, it is preferable that A / B is 0.01 to 25. When A / B is within the above range, the ratio of alumina to silanol groups is appropriate, and the charge rise is more easily improved due to acid-base interactions when stirred in the developer.

[0079] From the above viewpoint, the ratio A / B is more preferably 0.1 to 10, and even more preferably 1 to 5. The A / B ratio can be controlled within the above range by adjusting the amount of silanol groups in the carrier's resin coating layer and the amount of alumina particles added to the toner particles. The amount of silanol groups can be controlled by changing the mixing ratio of the bifunctional silane and tetrafunctional silane described above.

[0080] <Method for manufacturing toner particles and method for manufacturing toner> There are no particular limitations on the method for producing toner particles, and conventionally known manufacturing methods such as suspension polymerization, emulsification and agglomeration, melt kneading, and dissolution and suspension can be employed. The following describes an example of a toner manufacturing procedure using the melt-mixing method.

[0081] In the raw material mixing process, predetermined amounts of materials that constitute the toner particles, such as polyester resin, and, if necessary, other components such as mold release agents, colorants, and charge control agents, are weighed, blended, and mixed. Examples of mixing equipment include double-con mixers, V-type mixers, drum-type mixers, super mixers, Henschel mixers, Nauta mixers, and Mechanohybrid (manufactured by Nippon Coke Industries Co., Ltd.).

[0082] Next, the mixed materials are melt-kneaded to disperse wax and other substances in the binder resin. The mixing and dispensing temperature can be adjusted as appropriate depending on the binder resin and colorant used, but generally 100 to 180°C is preferred. In this melt-kneading process, batch-type mixers such as pressure kneaders and Banbury mixers, as well as continuous mixers, can be used, and single-screw or twin-screw mixers are the mainstream due to their advantage of being able to produce continuously.

[0083] Examples include the KTK twin-screw extruder (manufactured by Kobe Steel, Ltd.), the TEM twin-screw extruder (manufactured by Toshiba Machine Co., Ltd.), the PCM kneader (manufactured by Ikegai Iron Works Co., Ltd.), the twin-screw extruder (manufactured by KCK Co., Ltd.), the Co-kneader (manufactured by Buss Co., Ltd.), and the Nidex (manufactured by Nippon Coke Industries Co., Ltd.). Furthermore, the resin composition obtained by melt kneading may be rolled with two rolls or the like and cooled with water or the like in a cooling process.

[0084] Next, the cooled resin composition is pulverized to the desired particle size in a pulverization process. In the pulverization process, for example, it is coarsely pulverized using a pulverizer such as a crusher, hammer mill, or feather mill, and then further finely pulverized using a fine pulverizer such as a Kryptron system (manufactured by Kawasaki Heavy Industries), Super Rotor (manufactured by Nisshin Engineering Co., Ltd.), Turbo Mill (manufactured by Freund Turbo), or an air jet type pulverizer.

[0085] Subsequently, the material is classified as needed using classifiers and sieving machines such as the inertial classifier Elbow Jet (manufactured by Nippon Steel Mining Co., Ltd.), the centrifugal classifier Turboplex (manufactured by Hosokawa Micron Corporation), TSP separator (manufactured by Hosokawa Micron Corporation), and Faculty (manufactured by Hosokawa Micron Corporation) to obtain the classified product (toner particles).

[0086] To obtain positively charged toner, an external additive containing alumina particles is added to the resulting toner particles. The external additive may also contain silica particles or other external additives as needed. For mixing toner particles with external additives, mixing equipment such as a double-con mixer, V-type mixer, drum-type mixer, super mixer, Henschel mixer, Nauta mixer, Mechanohybrid (manufactured by Nippon Coke Industries Co., Ltd.), and Novilta (manufactured by Hosokawa Micron Corporation) can be used.

[0087] [Methods for measuring various physical properties] The following describes methods for measuring various physical properties. <Separation of magnetic carriers from developer> When separating and analyzing magnetic carriers from the developer, the following methods can be used. Add 30 mL of deionized water to a 100 mL flat-bottomed glass beaker. Add 0.3 mL of a dilution of "Contaminon N" (a 10% aqueous solution of a pH 7 neutral detergent for cleaning precision measuring instruments, consisting of a nonionic surfactant, anionic surfactant, and organic builder, manufactured by Wako Pure Chemical Industries, Ltd.) diluted three times by mass with deionized water to prepare the Contaminon N solution. Prepare an "Ultrasonic Dispension System Tetra150" (manufactured by Nikko Bios Co., Ltd.) with an electrical output of 120W, which incorporates two oscillators with an oscillation frequency of 50kHz, shifted in phase by 180 degrees. Add 3.3L of deionized water to the water tank of the ultrasonic disperser, and add 2mL of Contaminon N to this water tank. Place the beaker containing the Contaminon N solution into the beaker fixing hole of the ultrasonic disperser and activate the ultrasonic disperser. Then, adjust the height of the beaker so that the resonance state of the electrolytic solution surface inside the beaker is maximized. Add 1.0 g of magnetic carrier to the electrolytic aqueous solution in a beaker containing Contaminon N solution while irradiating it with ultrasound, and disperse it. Continue the ultrasonic dispersion treatment for 10 minutes. During ultrasonic dispersion, adjust the water temperature in the tank to 10°C to 40°C as appropriate. Next, a magnet is brought close to the beaker containing the magnetic carriers, attracting the carriers through the beaker. In this state, the supernatant liquid (contaminon N solution) in the beaker is removed, and the magnetic carriers can be obtained by repeating the washing process.

[0088] <Separation of external additives and toner particles from toner> External additives can be separated from toner by the following method. Add 200g of sucrose (manufactured by Kishida Chemical Co., Ltd.) to 100mL of deionized water and dissolve it over a water bath to prepare a concentrated sucrose solution. Place 31g of this concentrated sucrose solution and 6mL of Contaminon N (a 10% by mass aqueous solution of a pH 7 neutral detergent for cleaning precision measuring instruments, consisting of a nonionic surfactant, anionic surfactant, and organic builder, manufactured by Wako Pure Chemical Industries, Ltd.) into a centrifuge tube to prepare a dispersion. Add 1g of toner to this dispersion and break up any clumps of toner with a spatula or similar tool. The centrifugation tube is shaken in the shaker described above at a rate of 350 strokes per minute for 20 minutes. After shaking, the solution is transferred to a 50 mL glass tube for a swing rotor and centrifuged at 3500 rpm for 30 minutes. After centrifugation, the toner is present in the uppermost layer of the glass tube, and the external additive microparticles are present in the lower aqueous solution layer. The lower aqueous solution is collected and centrifuged to separate the sucrose from the microparticles, and the external additive microparticles are collected. If necessary, centrifugation is repeated to ensure sufficient separation, then the dispersion is dried and the external additive microparticles are collected. If multiple external additives are added, the additives can be separated using methods such as centrifugation. For example, if the external additive contains alumina particles and silica particles, they can be separated by centrifugation using a solvent with a specific gravity of approximately 2.5, or by density gradient centrifugation.

[0089] <Method for measuring the proportion of carbon atoms bonded to silicon atoms> The following describes how to measure the carbon, oxygen, and silicon concentrations on and near the surface of a carrier using ESCA. The carrier separated from the developer using the method described above can be used as the sample. The ESCA equipment and measurement conditions are as follows: Equipment: Quantum2000 (manufactured by ULVAC-FI) X-ray source: Monochromatized Al-Kα Sample measurement range: 100 μm in diameter Photoelectron acquisition angle: 45° X-ray: 50μm 12.5W 15kV Raster: 300μm × 200μm PassEnergy: 46.95eV Step Size: 0.200 eV Neutralizing electron gun: 20μA, 1V Ar ion gun: 7mA, 10V Sweep number: C 20 times, O 10 times, Si 15 times The measurement principle involves using an X-ray source to generate photoelectrons and measuring the energy based on the material's inherent chemical bonding.

[0090] From the peak intensities of each element measured, the surface atomic concentrations (atomic %) of carbon, oxygen, and silicon atoms are calculated using relative sensitivity factors provided by PHI. The obtained surface atomic concentration (atomic %) of carbon atoms is considered to be the surface atomic concentration of carbon atoms bonded to silicon atoms. The proportion of carbon atoms bonded to silicon atoms is calculated by determining the ratio of carbon concentration to the sum of carbon, oxygen, and silicon concentrations (dC / (dC+dO+dSi)×100).

[0091] <Method for measuring the amount of silanol groups on a carrier surface> The amount of silanol groups on the carrier surface is measured by titration using KOH. Specifically, it is measured using an improved method that quantifies silanol groups by titration based on the Sears method.

[0092] (Preparation of the measuring solution) Place 25.0g of carrier and 50ml of ethanol in a 200ml beaker, and shake the beaker by hand to wet the carrier with ethanol. Add 200ml of 20% NaCl aqueous solution, and disperse the fine particles (carrier) by ultrasonic dispersion for 1 minute to obtain a dispersion.

[0093] (measurement) Stir the above dispersion in the beaker with a stirrer. Then, while continuing to stir, add 0.1 mol / L HCl aqueous solution dropwise with a micropipette to adjust the pH to 4.0. Next, as the titration solution, add 0.1 mol / L KOH solution dropwise until the pH reaches 9.0. The amount of KOH (mol) in the solution added dropwise up to this point is calculated. Since KOH reacts with silanol groups present on the carrier surface, the amount of KOH (mol) calculated using the method described above can be considered as the amount of silanol groups (mol) on the carrier surface. Specifically, the amount of silanol groups per unit mass of carrier (mol / g) is calculated using the following formula and taken as the amount of silanol groups on the carrier surface. Silanol group amount (mol / g) = Amount of KOH added (mol) / Mass of carrier (g)

[0094] <Measurement of average circularity> The average circularity of alumina particles is measured using the flow-type particle image analyzer "FPIA-3000" (manufactured by Sysmex Corporation) under the measurement and analysis conditions used during calibration. Alumina particles separated from toner particles using the method described above can be used as the measurement sample. The specific measurement method is as follows:

[0095] First, 20 mL of deionized water, from which impurities and other contaminants have been removed, is placed in a glass container. To this, 0.2 mL of a diluted solution of "Contaminon N" (a 10% by mass aqueous solution of a pH 7 neutral detergent for cleaning precision measuring instruments, consisting of a nonionic surfactant, anionic surfactant, and organic builder, manufactured by Wako Pure Chemical Industries, Ltd.), diluted three times by mass with deionized water, is added as a dispersant. Furthermore, 0.02 g of the sample to be measured is added, and the mixture is dispersed using an ultrasonic disperser for 2 minutes to obtain the dispersion for measurement. During this process, the dispersion is cooled as needed so that its temperature is between 10°C and 40°C. As the ultrasonic disperser, a tabletop ultrasonic cleaner disperser ("VS-150" (manufactured by Velvo-Clear Co., Ltd.)) with an oscillation frequency of 50 kHz and an electrical output of 150 W is used, and a predetermined amount of deionized water is placed in the water tank, to which 2 mL of the aforementioned Contaminon N is added.

[0096] For the measurement, the flow-type particle image analyzer equipped with a standard objective lens (10x) is used, and the particle sheath "PSE-900A" (manufactured by Sysmex Corporation) is used as the sheath liquid. The dispersion prepared according to the above procedure is introduced into the flow-type particle image analyzer, and 3000 alumina particles are measured in HPF measurement mode and total count mode. Then, the binarization threshold for particle analysis is set to 85%, and the analyzed particle diameter is limited to a circular equivalent diameter of 1.985 μm or more and less than 39.69 μm, and the average circularity of the alumina particles is determined.

[0097] Before starting the measurement, autofocus adjustment should be performed using standard latex particles (Duke Scientific's "RESEARCH AND TEST PARTICLES Latex Microsphere Suspensions 5200A" diluted with deionized water). Subsequently, it is preferable to perform focus adjustment every two hours from the start of the measurement.

[0098] <EDS analysis of alumina particles> For alumina analysis using EDS, the EDS built into the JEOL JSM-IT800 can be used. The sample position is adjusted so that alumina is within the observation range at a magnification of 30-70k. The area containing alumina is then manually selected, and elemental mapping is performed. The mapping conditions are as follows: • Acceleration voltage: 20.00kV • Process time T4 Live time: 50.00 seconds Dead time: 20-30% The mapping results provide the weight percentages of Al and Sn elements relative to the weight of the alumina particles. EDS analysis is performed on five alumina particles to calculate the average weight percentages of Al and Sn elements. These average values ​​are set as the weight percentage of Al (x) and the weight percentage of Sn (y), respectively, and the value of x / y is calculated.

[0099] <Solid 29 Method for measuring the content ratio of constituent compounds in a resin coating layer using Si-NMR solid29 In Si-NMR, peaks are detected in different shift regions depending on the structure of the functional groups bonded to Si in the constituent compounds of the resin coating layer. By identifying each peak position using a standard sample, the structures bonded to Si can be identified. Furthermore, the abundance ratio of each constituent compound can be calculated from the obtained peak areas. The ratio of the peak areas of the M unit structure, D unit structure (b), and Q unit structure (a) to the total peak area can be calculated.

[0100] solid 29 The specific measurement conditions for Si-NMR are as follows: Equipment: JNM-ECX5002 (JEOL RESONANCE) Temperature: room temperature Measurement method: DDMAS method 29Si 45° Sample tube: Zirconia 3.2mmφ Sample: Filled in a test tube in powder form. Sample rotation speed: 10kHz Relaxation delay: 180s Scan: 2000

[0101] After the measurement, the silane components of the sample with different substituents and bonding groups are separated into peaks for the following M unit structure, D unit structure (b), T unit structure (c), and Q unit structure (a) by curve fitting, and the peak area of ​​each is calculated. The Q unit structure (a) corresponds to the monomer unit shown in formula (a) above, and the D unit structure (b) corresponds to the monomer unit shown in formula (b) above.

[0102] Curve fitting is performed using EXcalibur for Windows® version 4.2 (EX series), software for the JNM-EX400 manufactured by JEOL Ltd. The measurement data is loaded by clicking "1D Pro" from the menu icon. Next, "Curve fitting function" is selected from "Command" in the menu bar to perform curve fitting. Curve fitting is performed for each component so that the difference between the composite peak (the summation of each peak obtained by curve fitting) and the measured peak (composite peak difference) is minimized. M unit structure: (Ra)(Rb)(Rc)SiO 1 / 2 D unit structure: (Rd)(Re)Si(O 1 / 2 )2(b) T unit structure: RfSi(O 1 / 2 )3(c) Q Unit structure: Si(O) 1 / 2 )4(a) In the formula, Ra, Rb, Rc, Rd, Re, and Rf represent organic groups such as hydrocarbon groups with 1 to 6 carbon atoms (e.g., alkyl groups and alkoxy groups), halogen atoms, and hydroxyl groups bonded to silicon. The content ratios of (a), (b), and (c) in the resin coating layer are calculated from the peak areas corresponding to the structure represented by formula (a), the structure represented by formula (b), and the structure represented by formula (c) obtained by measurement. If it is necessary to confirm the structure in more detail, 29 Along with the Si-NMR measurement results 13 C-NMR and 1 The results of the 1H-NMR measurement may also be used for identification.

[0103] <Method for measuring silica surface treatment agents> The compositional analysis of silica surface treatment agents is performed using a nuclear magnetic resonance (NMU) spectrometer. 15 N-NMR, 13 This can be performed using 1C-NMR and FT-IR. By comparing the obtained spectra with those of known library spectra, the surface treatment agent can be identified. The following describes the equipment used. (i) 15 N-NMR, 13 C-NMR Measuring device: FT NMR device JNM-EX400 (manufactured by JEOL Ltd.) Measurement frequency: 400MHz Pulse condition: 5.0 μs Frequency range: 10500Hz Total number of times: 64 (ii) FT-IR Thermo Fisher Scientific Inc. AVATAR360FT-IR

[0104] The alumina content (Amol) per 100g of two-component developer is measured by the following method. Before separating the carrier from the two-component developer using the method described above, measure the mass (g) of the two-component developer. Also, when separating the external additive from the toner using the method described above, and then separating the alumina from the external additive, measure the mass (g) of the separated alumina. From the measured mass of the two-component developer and the mass of alumina, the mass of alumina (g) per 100g of the two-component developer can be determined. Dividing this by the molecular weight of alumina gives the alumina content (Amol) per 100g of the two-component developer. The amount of silanol groups (Bmol) per 100g of a two-component developer is measured by the following method. The carrier is separated from the two-component developer using the same method as described above, and the carrier mass (g) per 100g of the two-component developer is determined. Then, the amount of silanol groups per unit mass of the carrier (mol / g) is determined by titration with KOH as described above. The amount of silanol groups (Bmol) per 100g of a two-component developer can be determined from the carrier mass (g) per 100g of the two-component developer and the amount of silanol groups per unit mass of carrier (mol / g). The value of A / B is calculated from the values ​​of A and B obtained using the method described above.

[0105] ​<Method for identifying barium titanate particles in a two-component developer> Toluene is added to the carrier separated from the two-component developer using the method described above, and the mixture is stirred to dissolve the coating resin. By filtering this solution, the particles contained in the coating resin can be recovered. By analyzing these particles using FT-IR or XRD, barium titanate particles can be identified.

[0106] <Method for identifying charge control agents in two-component developer systems> The toner particles separated by the method described above are dissolved in tetrahydrofuran (THF), and the insoluble matter is recovered. The type of charge control agent can be identified by analyzing the recovered insoluble matter using IR or H-NMR. If the above analysis detects a peak derived from a quaternary ammonium salt, it is determined that the toner particles contain a quaternary ammonium salt as a charge control agent.

[0107] <Method for measuring the alumina particle content in toner> The toner and carrier are separated from the two-component developer using the method described above, and the mass of the toner is measured. Furthermore, the external additive is separated from the toner, and then the alumina particles are separated from the external additive, and the mass of the alumina particles is measured. The alumina particle content in the toner is calculated from the measured values. [Examples]

[0108] This disclosure will be specifically illustrated by the following embodiments. However, these embodiments are not intended to limit this disclosure in any way. Unless otherwise specified, all "parts" in the following formulations refer to mass.

[0109] <Example of manufacturing for Carrier 1> (1) In a 500 ml beaker, 100.0 g of methanol, 8.0 g (0.44 mol) of pure water, 0.004 g of acetic acid as a catalyst, 15.0 g (0.12 mol) of dimethyldimethoxysilane, 15.0 g (0.07 mol) of tetraethoxysilane, and 0.50 g of barium titanate with a particle size of 100 nm were charged and stirred at 45°C for 5 minutes to prepare an aqueous solution. (2) 2.0 g of 28% aqueous ammonia was added to the above aqueous solution and stirred at 30°C for 3.0 hours to obtain an oligomer solution. (3) 500.0 g of MnMg ferrite core (particle size 35 μm) was coated with the entire amount of the above-mentioned oligomer solution using a rolling fluidized bed coating apparatus. The coating conditions were: supply air temperature 75°C, supply air volume 0.3 m³. 3 The conditions were a flow rate of 1 / min and a rotor speed of 400 rpm. The amount of oligomer solution introduced into the fluidized bed coating apparatus was adjusted so that the mass ratio of the resin coating layer to the carrier core particles was 1.5% by mass (i.e., for every 1000 g of carrier core, the mass of the coating layer formed by heating was 15 g). After drying the solvent in an 80°C oven for 1 hour, carrier 1 was obtained by heating in an electric furnace at 200°C for 2 hours. The physical properties of the obtained carrier 1 are shown in Table 1.

[0110] <Example of Carrier 2 manufacturing> Carrier 2 was obtained in the same manner as in the production example of carrier 1, except that barium titanate was not added. The physical properties of the obtained carrier 2 are shown in Table 1.

[0111] <Example of Carrier 3 manufacturing> Carrier 3 was obtained in the same manner as in the example of preparing carrier 2, except that tetraethoxysilane was changed to 12.5 g (0.06 mol) and dimethyldimethoxysilane to 17.5 g (0.15 mol). The physical properties of the obtained carrier 3 are shown in Table 1.

[0112] <Example of Carrier 4 manufacturing> Carrier 4 was obtained in the same manner as in the example of preparing carrier 2, except that tetraethoxysilane was changed to 17.5 g (0.08 mol) and dimethyldimethoxysilane to 12.5 g (0.10 mol). The physical properties of the obtained carrier 4 are shown in Table 1.

[0113] <Example of manufacturing for Carrier 5> Coating resin dispersion 1 was obtained by dispersing 16.0 g of PTFE in 100.0 g of toluene. 12.0 g of the above-mentioned coating resin dispersion 1 was coated onto 100.0 g of the above-mentioned MnMg ferrite core using a rolling fluidized bed coating apparatus. Subsequently, a fluororesin coated carrier was obtained by heating the coated carrier core at 200°C for 2 hours. Carrier 5 was obtained in the same manner as in the manufacturing example of carrier 1, except that the above-mentioned fluororesin-coated carrier was used instead of the MnMg ferrite core. The physical properties of the obtained carrier 5 are shown in Table 1.

[0114] <Example of Carrier 6 manufacturing> Carrier 6 was obtained in the same manner as in the production example of carrier 2, except that tetraethoxysilane was changed to 15.0 g (0.07 mol) and dimethyldimethoxysilane to 12.5 g (0.10 mol). The physical properties of the obtained carrier 6 are shown in Table 1.

[0115] <Example of Carrier 7 manufacturing> Carrier 7 was obtained in the same manner as in the production example of carrier 2, except that tetraethoxysilane was changed to 15.0 g (0.07 mol) and dimethyldimethoxysilane to 10.0 g (0.08 mol). The physical properties of the obtained carrier 7 are shown in Table 1.

[0116] <Example of Carrier 8 manufacturing> Carrier 8 was obtained in the same manner as in the production example for carrier 2, except that tetraethoxysilane was changed to 7.5 g (0.04 mol) and dimethyldimethoxysilane was changed to 7.5 g (0.06 mol). The physical properties of the obtained carrier 8 are shown in Table 1.

[0117] <Example of Carrier 9 manufacturing> 100.0 g of carrier 2 was coated with 12.0 g of the above-mentioned coating resin dispersion 1 using a rolling fluidized bed coating apparatus. Subsequently, the coated carrier core was heated at 200°C for 2 hours to obtain the carrier. The physical properties of the obtained carrier 9 are shown in Table 1.

[0118] <Example of manufacturing for Carrier 10> (Preparation of coating solution (L1)) A coating solution (L1) was prepared to be used to form a coating layer on the carrier. 361.2 g of silicone resin solution (solid content: 161.1 g), 36.2 g of barium titanate particles, 14.4 g of carbon black, and 1444.8 g of toluene were placed in a stainless steel container. The contents of the container were mixed using a homogenizer to obtain coating solution (L1). Details of the materials used in coating solution (L1) are as follows. As the silicone resin solution, Shin-Etsu Chemical Co., Ltd.'s "KR-255" (solid content: methylphenyl silicone resin, solid content concentration: 50% by mass) was used. As the barium titanate particles, Sakai Chemical Industry Co., Ltd.'s "BT-01" (number average primary particle diameter: 304 nm) was used. As the carbon black, Lion Specialty Chemicals Co., Ltd.'s conductive carbon black "Ketjenblack® EC300J" (number average primary particle diameter: 39.5 nm) was used.

[0119] (Preparation of carrier parent particles) Using a fluidized bed coating apparatus (FD-MP-01 D model, manufactured by Powrec Co., Ltd.), a coating solution (L1) was sprayed onto a 5000g carrier core while it was being fluidized. A manganese ferrite core (manufactured by DOWA IP Creation Co., Ltd., median diameter: 40 μm, saturation magnetization: 67 emu / g) was used as the carrier core. The coating conditions were: supply air temperature 75°C, supply air volume 0.3 m³. 3 The conditions were a rotation speed of 400 rpm and a rotation speed of 1000 rpm. The amount of coating liquid (L1) introduced into the fluidized bed coating apparatus was adjusted so that the mass ratio of the resin coating layer to the carrier core particles was 1.5% by mass (i.e., for every 1000 g of carrier core, the mass of the coating layer formed by heating was 15 g). A carrier core coated with coating liquid (L1) was obtained by the above spraying method. Next, the carrier core coated with coating liquid (L1) was fired in an electric furnace at 200°C for 1 hour to form a coating layer on the surface of the carrier core. In this way, carrier 10 was obtained. The physical properties of the obtained carrier 10 are shown in Table 1.

[0120] <Example of Carrier 11 manufacturing> Carrier 11 was obtained in the same manner as in the example of preparing carrier 2, except that tetraethoxysilane was changed to 25.0 g (0.12 mol) and dimethyldimethoxysilane to 5.0 g (0.04 mol). The physical properties of the obtained carrier 11 are shown in Table 1.

[0121] [Table 1] In the table, "Si-OH amount" indicates the amount of silanol groups on the carrier surface, measured by titration using KOH. "Si-C ratio" indicates the ratio of carbon atoms bonded to silicon atoms to the total amount of carbon atoms, oxygen atoms, and silicon atoms present on the carrier surface, as determined by X-ray photoelectron spectroscopy (ESCA).

[0122] <Example of Alumina Particle Production> 18.0 g of tin chloride pentahydrate was dissolved in 100 mL of 2N hydrochloric acid to obtain a solution (I) of tin chloride pentahydrate. A core slurry was obtained by dispersing 100g of alumina substrate (Sumitomo Chemical "AKP-50") in 1 liter of water. The slurry was heated to 70°C and maintained at the same temperature. While adjusting the pH of the slurry to be between 7 and 8, the entire amount of tin chloride pentahydrate solution (I) and 6.7N aqueous ammonia were added dropwise to the slurry over 40 minutes. After filtering and washing the slurry, it was dried at 110°C to obtain a dried product. The dried product was heat-treated at 500°C for 1 hour in a nitrogen gas stream at a flow rate of 1 L / min to obtain alumina particles 1. The physical properties of the obtained alumina particles 1 are shown in Table 2.

[0123] <Example of Alumina Particle 2 Production> Alumina particle 2 was obtained in the same manner as in the production example of alumina particle 1, except that the amount of tin chloride pentahydrate added was changed to 23.0 g. The physical properties of the obtained alumina particle 2 are shown in Table 2.

[0124] <Example of Alumina Particle 3 Production> Alumina particle 3 was obtained in the same manner as in the production example of alumina particle 1, except that the amount of tin chloride pentahydrate added was changed to 12.0 g. The physical properties of the obtained alumina particle 3 are shown in Table 2.

[0125] <Example of Alumina Particle Production> Without surface treatment, the alumina substrate (Sumitomo Chemical "AKP-50") was used directly as alumina particle 4. The physical properties of alumina particle 4 are shown in Table 2.

[0126] <Example of Alumina Particle 5 Production> Alumina particle 5 was obtained in the same manner as in the production example of alumina particle 1, except that the amount of tin chloride pentahydrate added was changed to 8.0 g. The physical properties of the obtained alumina particle 5 are shown in Table 2.

[0127] <Example of Alumina Particle 6 Production> Alumina particle 6 was obtained in the same manner as in the production example of alumina particle 1, except that the alumina substrate used was changed to Admatex "AO-502". The physical properties of the obtained alumina particle 6 are shown in Table 2.

[0128] [Table 2]

[0129] <Examples of toner manufacturing> <Example of Polyester Resin A1 Production> • Polyoxypropylene(2,2)-2,2-bis(4-hydroxyphenyl)propane : 76.9 parts (0.167 moles) Terephthalic acid (TPA): 25.0 parts (0.145 moles) • Adipic acid: 8.0 parts (0.054 moles) Titanium tetrabutoxide: 0.5 parts The above materials were placed in a 4-liter four-necked glass flask, and a thermometer, stirring rod, condenser, and nitrogen inlet tube were attached and placed inside a mantle heater. Next, the flask was purged with nitrogen gas, and the temperature was gradually increased while stirring. The mixture was then reacted at 200°C for 4 hours while stirring (first reaction step). Subsequently, 1.2 parts (0.006 mol) of trimellitic anhydride (TMA) was added, and the mixture was reacted at 180°C for 1 hour (second reaction step) to obtain polyester resin A1, which is the binder resin component. The acid value of this polyester resin A1 was 5 mg KOH / g.

[0130] <Example of Polyester Resin A2 Manufacturing> • Polyoxypropylene(2,2)-2,2-bis(4-hydroxyphenyl)propane : 71.3 parts (0.155 moles) Terephthalic acid: 24.1 parts (0.145 moles) Titanium tetrabutoxide: 0.6 parts The above materials were placed in a 4-liter, four-necked glass flask, and a thermometer, stirring rod, condenser, and nitrogen inlet tube were attached and placed inside a mantle heater. Next, the flask was purged with nitrogen gas, and the temperature was gradually increased while stirring. The mixture was then reacted at 200°C for 2 hours while stirring. After that, 5.8 parts (0.030 mol) of trimellitic anhydride was added, and the mixture was reacted at 180°C for 10 hours to obtain polyester resin A2. The acid value of this polyester resin A2 was 10 mg KOH / g.

[0131] <Example of toner particle 1 manufacturing> • Polyester resin A1 70.0 parts • Polyester resin A2 30.0 parts Fischer-Tropsch wax (peak temperature of maximum endothermic peak: 78°C) 5.0 parts CI Pigment Blue 15:3 5.0 parts Decyltrimethylammonium chloride 0.2 parts The raw materials shown in the above formula were mixed using a Henschel mixer (FM-75 model, manufactured by Nippon Coke Industries Co., Ltd.) at a rotation speed of 20 seconds.-1 After mixing for 5 minutes, the mixture was kneaded in a twin-shaft kneader (PCM-30 model, manufactured by Ikegai Co., Ltd.) set to a temperature of 125°C and a rotation speed of 300 rpm. The resulting mixture was cooled and coarsely ground to a diameter of 1 mm or less using a hammer mill to obtain coarse material. The obtained coarse material was finely ground using a mechanical pulverizer (T-250, manufactured by Freund Turbo Co., Ltd.). Further classification was performed using a rotary classifier (200TSP, manufactured by Hosokawa Micron Corporation) to obtain toner particles 1. The operating conditions for the rotary classifier (200TSP, manufactured by Hosokawa Micron Corporation) were a classification rotor rotation speed of 50.0 s. -1 Classification was performed. The resulting toner particles 1 had a weight-average particle size (D4) of 5.9 μm.

[0132] <Example of toner particle 2 manufacturing> Toner particle 2 was obtained in the same manner as in the example of toner particle 1, except that an aluminum compound 3,5-di-t-butylsalicylate was used instead of decyltrimethylammonium chloride.

[0133] <Example of toner particle 3 manufacturing> Toner particle 3 was obtained in the same manner as in the example of toner particle 1, except that decyltrimethylammonium chloride was not added.

[0134] <Example of silica particle production> 500 g of fumed silica (silica microparticle substrate) with a number-average particle size of 30 nm was placed in a reaction vessel, and the reaction vessel was heated and stirred under nitrogen purging, with the temperature controlled to 330°C. Next, 3-aminopropyltriethoxysilane vapor was supplied to the reaction vessel at a rate of 10 g / min for 60 minutes as a surface treatment agent. After that, the silica microparticle substrate was surface-treated by heating and stirring for 180 minutes. Then, the reaction vessel was purged with nitrogen to remove unreacted surface treatment agent, and silica particles 1 were obtained.

[0135] <Example of silica particle production> Silica particles 2 were obtained in the same manner as in the example of producing silica particles 1, except that hexamethyldisilazane was used instead of 3-aminopropyltriethoxysilane.

[0136] <Example of Toner 1 manufacturing> • Toner particles 1 100 copies • Silica particles 1 2.0 parts • Alumina particles 1 2.0 parts The above ingredients were mixed in a Henschel FM-10C mixer (manufactured by Mitsui Miike Chemical Machinery) at a rotation speed of 30 seconds. -1 The mixture was mixed for a rotation time of 10 minutes to obtain toner 1.

[0137] <Manufacturing examples for toners 2-14> In the manufacturing example of Toner 1, the same procedure was followed except that the types and amounts of alumina and silica particles were changed as shown in Table 3, and Toners 2 to 14 were obtained.

[0138] [Table 3]

[0139] <Example of manufacturing a two-component developer 1> 92.0 parts of carrier 1 and 8.0 parts of toner 1 were added and mixed using a V-type mixer (V-20, manufactured by Seishin Corporation) to obtain a two-component developer 1. The physical properties of the two-component developer 1 are shown in Table 4.

[0140] <Manufacturing examples of two-component developers 2-22> In the example of manufacturing two-component developer 1, the manufacturing process was carried out in the same manner except that the types of carrier and toner were changed as shown in Table 4, to obtain two-component developers 2 to 22. The physical properties of two-component developers 2 to 22 are shown in Table 4.

[0141] [Table 4]

[0142] <Toner Evaluation Method> The following evaluations were performed using the developers 1-18 and comparative developers 19-22 obtained above. An image forming apparatus, an imagePRESS C800 (manufactured by Canon), was used. The exposure of the developer carrier was reversed, and the DC voltage VDC and transfer current were modified to allow free setting of these parameters, enabling the output of an image of a developer for positively charged toner. The aforementioned two-component developer was placed in the cyan position of the modified machine, and the charging voltage VD of the electrostatic latent image carrier, the DC voltage VDC of the developer carrier, and the laser power were adjusted so that the amount of toner on the paper was the desired amount. The following evaluations were performed using the image forming apparatus described above.

[0143] (1) Method for evaluating durability (image density change) A Canon imageRUNNER ADVANCE C5255 full-color copier was used as the image forming apparatus. Image output evaluation (A4 landscape, 80% print coverage, 1,000 sheets continuously fed) was performed under normal temperature and humidity conditions (N / N; temperature 23°C / humidity 50%RH). During the 1,000 sheets continuous feeding time, the same development and transfer conditions (no calibration) as the first sheet were used. The evaluation paper was copy paper (CS-814 (A4, basis weight 81.4g / m²)). 2 (Sold by Canon Marketing Japan Inc.) In this evaluation environment, the amount of toner applied to the paper in the FFH image (solid areas) was 0.4 mg / cm². 2 It was adjusted to be as follows. The FFH image is a value that displays 256 gradations in hexadecimal. 00H is defined as the 1st grayscale level (white background), and FFH is defined as the 256th grayscale level (solid color area). The following evaluations were performed on the initial (first image) and after 1,000 consecutive pages were fed through (1,000th image) FFH images. [Image density measurement for the initial (first) image and 1,000 consecutive images] An X-Rite color reflectance densitometer (500 series: manufactured by X-Rite) was used to measure the image density (solid area) of the FFH image area at the initial stage (1st sheet) and after continuous paper feeding (1,000th sheet). From the measured values, the difference in image density of the FFH image area (solid area) at the initial stage (1st sheet) and after continuous paper feeding (1,000th sheet) was calculated and evaluated according to the following criteria. A rating of C or higher was considered to indicate good durability. The evaluation results are shown in Table 5. (Evaluation Criteria) A: Image density difference is less than 0.05 B: Image density difference is 0.05 or more and less than 0.10 C: Image density difference is 0.10 or greater and less than 0.20 D: Image density difference is 0.20 or greater

[0144] (2) Method for evaluating the rate of charge rise The charge rise time was evaluated by measuring the change in density when outputting images with different image print ratios. After outputting an image with a low image ratio to saturate the charge of the toner in the developing machine, an image with a high image ratio was output. This resulted in a change in density due to the difference in charge between the saturated toner in the developing machine and the newly supplied toner. Toner with a fast charge rise time saturates immediately after being supplied to the developing machine, resulting in less change in density. On the other hand, toner with a slow charge rise time takes longer to saturate after being supplied to the developing machine, causing the overall charge of the toner to decrease and resulting in a change in density. First, a test print of 1000 images was performed with an image ratio of 1%. During the continuous feeding of 1000 images, the same development and transfer conditions (without calibration) as the first image were used. Subsequently, a test print of 1000 images was performed with an image ratio of 80%. During the continuous feeding of 1000 images, the same development and transfer conditions (without calibration) as the first image were used. The image density of the 1000th image printed at an image ratio of 1% was used as the initial density, and the density of the 1000th image printed at an image ratio of 80% was measured and evaluated according to the following evaluation criteria. The above tests were conducted under normal temperature and low humidity conditions (N / L; temperature 23°C, humidity 5%RH). (Measurement of image density changes) Using an X-Rite color reflectance densitometer (500 series: manufactured by X-Rite), the initial density (density of the 1000th image printed at an image ratio of 1%) and the density of the 1000th image printed at an image ratio of 80% were measured, and the difference in image density was ranked according to the following criteria. A rating of E or higher was considered to indicate good charge rise. The evaluation results are shown in Table 5. (Evaluation Criteria) AA: Image density difference is less than 0.02 A: Image density difference is less than 0.04 B: Image density difference is 0.04 or greater and less than 0.06 C: Image density difference is 0.06 or greater and less than 0.08 D: Image density difference is 0.08 or greater and less than 0.10 E: Image density difference is 0.08 or greater and less than 0.12 F: Image density difference is 0.12 or greater.

[0145] (3) Method for evaluating charge retention The amount of triboelectric charge on the toner on the electrostatic latent image carrier was calculated by collecting the toner using a metal cylindrical tube and a cylindrical filter. Specifically, the amount of triboelectric charge on the toner on the electrostatic latent image carrier was measured using a Faraday cage. A Faraday cage is a coaxial double-cylinder structure where the inner and outer cylinders are insulated from each other. If a charged object with charge Q is placed inside the inner cylinder, electrostatic induction will cause it to behave as if a metal cylinder with charge Q were present. The amount of induced charge was measured using an electrometer (Kessley 6517A, manufactured by Kessley), and the amount of charge Q (mC) divided by the mass of toner M (kg) in the inner cylinder (Q / M) was defined as the amount of triboelectric charge of the toner. The amount of triboelectric charge on toner (mC / kg) = Q / M First, the following evaluation image was formed on the electrostatic latent image carrier. Before it was transferred to the intermediate transfer medium, the rotation of the electrostatic latent image carrier was stopped, and the toner on the electrostatic latent image carrier was collected by suction using a metal cylindrical tube and a cylindrical filter, and the [initial Q / M] was measured. <Evaluation Image> Paper type: GFC-081 (81.0g / m 2 (Canon Marketing Japan Inc.) Toner coverage on paper: 0.35 mg / cm² 2 (Adjusted by the DC voltage VDC of the developer carrier, the charging voltage VD of the electrostatic latent image carrier, and the laser power) Evaluation image: A 2cm x 5cm image is placed in the center of the A4 paper shown above. Fixation test environment: High temperature and high humidity environment (H / H; temperature 30℃ / humidity 80%RH) Process speed: 377 mm / sec Subsequently, the developer was left inside the evaluation unit in an H / H environment for two weeks. After that, the same procedure as before was performed, and the amount of charge per unit mass Q / M (mC / kg) on ​​the electrostatic latent image carrier after the period of inactivity was measured. The initial Q / M per unit mass on the electrostatic latent image carrier was set to 100%, and the charge retention rate per unit mass on the electrostatic latent image carrier after standing ([Q / M after standing] / [Initial Q / M] × 100) was calculated and judged according to the following criteria. A rating of D or higher was judged to indicate good charge retention in high temperature and high humidity environments. The evaluation results are shown in Table 5. (Evaluation Criteria) A: Static charge retention rate of 98% or higher B: Static charge retention rate is 95% or more but less than 98% C: Static resistance rate is 90% or more but less than 95% D: Static charge retention rate is 85% or more but less than 90% E: Static electricity retention rate is less than 80%

[0146] [Table 5]

[0147] This disclosure relates to the following configuration. (Composition 1) A two-component developer comprising a positively charged toner and a carrier, (i) The carrier comprises carrier core particles and a resin coating layer covering the surface of the carrier core particles, wherein the resin coating layer contains a silicone resin. (ii) The amount of silanol groups on the carrier surface, as measured by titration using KOH, is 4.00 × 10⁻⁶. -6 mol / g or more 4.00×10 -4 It is less than or equal to mol / g. The positively charged toner comprises toner particles and external additive particles. The external additive particles include alumina particles. A two-component developer characterized by the following features. (Configuration 2) The two-component developer according to configuration 1, wherein the ratio of carbon atoms bonded to silicon atoms to the total amount of carbon atoms, oxygen atoms, and silicon atoms, as measured by X-ray photoelectron spectroscopy (ESCA) of the carriers, is 30 atm% or more. (Composition 3) The aforementioned external additive particles include silica particles, A two-component developer according to configuration 1 or 2, wherein the silica particles are surface-treated with a treatment agent having an amino group. (Composition 4) The toner particles contain a quaternary ammonium salt as a charge control agent, wherein the two-component developer is as described in any of configurations 1 to 3. (Composition 5) A two-component developer according to any one of configurations 1 to 4, wherein the resin coating layer consists of a single layer. (Composition 6) A two-component developer according to any one of configurations 1 to 5, wherein the content of alumina particles per 100 parts by mass of toner particles is 0.1 to 10.0 parts by mass. (Composition 7) Let Amol be the amount of alumina contained in 100g of the aforementioned two-component developer. When the amount of silanol groups on the carrier surface per 100g of the two-component developer is Bmol, A two-component developer according to any of the compositions 1 to 6, wherein the A / B ratio is 0.01 to 25. (Composition 8) A two-component developer according to any one of the components 1 to 7, wherein the average circularity of the alumina particles is 0.950 or less. (Composition 9) The surface of the alumina particles is covered with a conductive layer containing tin. When x is the weight percentage of Al element detected in the EDS analysis of the alumina particles, and y is the weight percentage of Sn element, A two-component developer according to any of the configurations 1 to 8, wherein x / y is between 1.0 and 1.7. (Composition 10) A two-component developer according to any one of configurations 1 to 9, wherein the resin coating layer contains barium titanate particles. (Composition 11) A two-component developer according to any of configurations 1 to 10, wherein the structure, excluding the ends of the silicone resin, consists only of units represented by the following formulas (a) and (b). [ka] (R 1 , R 2 Each of these independently represents an alkyl group with 1 to 6 carbon atoms.

Claims

1. A two-component developer comprising a positively charged toner and a carrier, (i) The carrier comprises carrier core particles and a resin coating layer covering the surface of the carrier core particles, wherein the resin coating layer contains a silicone resin. (ii) The amount of silanol groups on the carrier surface, as measured by titration using KOH, is 4.00 × 10 －６ mol / g or more 4.00×10 －４ It is less than or equal to mol / g. The positively charged toner comprises toner particles and external additive particles. The external additive particles include alumina particles. A two-component developer characterized by the following features.

2. The two-component developer according to claim 1, wherein the ratio of carbon atoms bonded to silicon atoms to the total amount of carbon atoms, oxygen atoms, and silicon atoms, as measured by X-ray photoelectron spectroscopy (ESCA) of the carrier, is 30 atm% or more.

3. The aforementioned external additive particles include silica particles, The two-component developer according to claim 1 or 2, wherein the silica particles are surface-treated with a treatment agent having an amino group.

4. The two-component developer according to claim 1 or 2, wherein the toner particles contain a quaternary ammonium salt as a charge control agent.

5. The two-component developer according to claim 1 or 2, wherein the resin coating layer consists of a single layer.

6. The two-component developer according to claim 1 or 2, wherein the content of alumina particles per 100 parts by mass of toner particles is 0.1 to 10.0 parts by mass.

7. Let Amol be the amount of alumina contained in 100 g of the aforementioned two-component developer. When the amount of silanol groups on the carrier surface per 100 g of the two-component developer is B mol, A two-component developer according to claim 1 or 2, wherein the A / B ratio is 0.01 to 25.

8. The two-component developer according to claim 1 or 2, wherein the average circularity of the alumina particles is 0.950 or less.

9. The surface of the alumina particles is covered with a conductive layer containing tin. When x is the weight percentage of Al element detected in the EDS analysis of the alumina particles, and y is the weight percentage of Sn element, A two-component developer according to claim 1 or 2, wherein x / y is 1.0 to 1.

7.

10. The two-component developer according to claim 1 or 2, wherein the resin coating layer contains barium titanate particles.

11. The two-component developer according to claim 1 or 2, wherein the structure excluding the ends of the silicone resin is composed only of units represented by the following formulas (a) and (b). 【Chemistry 1】 (R １ , R ２ Each of these independently represents an alkyl group with 1 to 6 carbon atoms.

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