toner

Abstract

To provide toner which may have the excellent fluidity and whose fluidity hardly changes over time even in a case where image output is continuously performed, namely provide toner which may have the excellent flow maintenance property.SOLUTION: An external additive particle includes a sulfur-containing polymer. The polymer includes a vinyl polymer moiety and a siloxane moiety. The proportion of the number of silicon atoms to the sum of the number of carbon atoms, the number of oxygen atoms, and the number of silicon atoms in the external additive particle is 4.0% or more and 25.0% or less, and sulfur atoms are contained in the surface of the external additive particle as detected by X-ray photoelectron spectroscopy.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a toner used in an electrophotographic image forming apparatus. [Background technology]

[0002] In recent years, there has been a demand for even higher speeds and longer life for image forming apparatuses using electrophotography. In response to these demands, toners that have stress resistance that allows them to withstand long periods of friction in developing devices and that have excellent fluidity in order to obtain high image quality even in high-speed printing have been studied.

[0003] Patent Document 1 discloses that the fluidity and the like of a toner can be improved by incorporating a toner additive having an organic polymer skeleton and a polysiloxane skeleton into the toner. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 8-202071 Summary of the Invention [Problem to be solved by the invention]

[0005] As a result of the inventors' investigation into the toner described in Patent Document 1, they recognized that further improvement is required regarding the change in the fluidity of the toner over time when continuous image output is performed.

[0006] One aspect of the present disclosure is to provide external additive particles that can provide a toner that has excellent fluidity and is less likely to change in fluidity over time even when continuous image output is performed, i.e., a toner that can have excellent fluidity retention properties. [Means for solving the problem]

[0007] One aspect of the present disclosure is an external additive particle including a polymer having a sulfur atom, the polymer has a vinyl polymer portion and a siloxane portion; the ratio of the number of silicon atoms to the total number of carbon atoms, oxygen atoms, and silicon atoms in the external additive particles is 4.0% or more and 25.0% or less, The external additive particles are characterized in that, when X-ray photoelectron spectroscopy is performed on the surface of the external additive particles, sulfur atoms are detected. [Effects of the Invention]

[0008] According to one aspect of the present disclosure, it is possible to provide a toner that can have excellent fluidity and maintain excellent fluidity even when continuous image output is performed. DETAILED DESCRIPTION OF THE INVENTION

[0009] The expressions "xx or more and xx or less" or "xx to xx" that represent a numerical range mean a numerical range that includes the endpoints, that is, the lower limit and the upper limit, unless otherwise specified.

[0010] When numerical ranges are stated in stages, the upper and lower limits of each numerical range can be combined in any way.

[0011] <Background to the invention> As a result of the inventors' investigations, it was found that external additive particles containing a polymer having a vinyl polymer moiety and a siloxane moiety, and further controlling the proportion of silicon atoms in the external additive particles, tend to increase the fluidity of the toner to which the external additive particles are added. On the other hand, it was discovered that when continuous image output is performed using the toner, the toner's fluidity may be difficult to maintain, that is, the toner's fluidity maintenance may be insufficient. The inventors speculate that this is because the external additive particles may be easily detached from the toner during continuous image output, and the detachment of the external additive particles from the toner reduces the fluidity of the toner. Furthermore, the inventors believe that the external additive particles are easily detached from the toner because, when the toner is subjected to a load during continuous image output, the adhesive force due to the affinity between the vinyl polymer moiety in the external additive particles and the toner resin may not be sufficient.

[0012] From the viewpoint of increasing the speed of image forming apparatuses and obtaining high-quality images, it is naturally required that the toner has excellent fluidity maintaining properties, and it has been recognized that improvements in this regard are necessary.

[0013] Based on the above considerations, the present inventors have investigated external additive particles that can produce toners that can have excellent fluidity and excellent flow retention. As a result of extensive investigation, they have found that by further incorporating sulfur atoms into the polymer contained in the external additive particles and causing sulfur atoms to be present on the surface of the external additive particles, toners to which the external additive particles have been externally added are effective as toners with the above-mentioned properties. Each of the constituent elements will be described in detail below.

[0014] <Sulfur atoms on the surface of external additive particles> The polymer according to the present disclosure contains sulfur atoms, and when X-ray photoelectron spectroscopy is performed on the surface of the external additive particles, sulfur atoms are detected. That is, sulfur atoms are present in the surface region of the external additive particles. The present inventors have discovered that when the polymer contains sulfur atoms and when sulfur atoms are present in the surface region of the external additive particles, a toner having excellent fluidity retention properties is more easily obtained. Although the reason for the improved fluidity retention properties is unclear, the present inventors speculate as follows.

[0015] Sulfur, a period 3 element, has a larger principal quantum number than period 2 elements such as carbon, resulting in a smaller energy difference between atomic orbitals and greater hybridization. Therefore, orbitals are more likely to be distorted by external electrostatic fields; that is, sulfur atoms have a relatively high polarizability, and polarized portions are more likely to generate electrostatic interactions with the outside. Even when sulfur atoms are covalently bonded to highly electronegative atoms such as oxygen atoms, polarization also occurs in the bond between the sulfur atom and the oxygen atom, and the polarized portions are more likely to generate electrostatic interactions with the outside. Furthermore, the presence of polarized portions in the surface regions of external additive particles is thought to facilitate strong interactions with portions capable of electrostatic interaction present on the toner particle surface, making it difficult for the external additive particles to separate from the toner particle surface. The present inventors believe that this will result in a toner that can exhibit excellent fluidity retention, even when continuous image output is performed. Furthermore, because excellent fluidity retention is more likely to be obtained, it is preferable that sulfur atoms contained in the polymer according to the present disclosure be detected when X-ray photoelectron spectroscopy is performed on the surface of the external additive particles.

[0016] Furthermore, when X-ray photoelectron spectroscopy is performed on the surface of the external additive particles, the ratio of the number of sulfur atoms to the total number of carbon atoms, oxygen atoms, silicon atoms, and sulfur atoms is more preferably 0.10% or more and 0.50% or less, more preferably 0.30% or less, and even more preferably 0.20% or less. The present inventors believe that when the ratio of the number of sulfur atoms is within the above range, the interaction between the surface of the toner particles and the external additive particles can be easily and appropriately controlled.

[0017] Examples of sulfur atoms in moieties that readily induce electrostatic interactions include sulfo groups (-SO3H) and sulfate groups (-OSO3H), as well as their sodium and potassium salts. Therefore, the polymer according to the present disclosure is preferably a polymer having at least one functional group selected from the group consisting of -SO3H, -SO3Na, -SO3K, -OSO3H, -OSO3Na, and -OSO3K. Furthermore, the sulfur atoms detected by X-ray photoelectron spectroscopy are preferably sulfur atoms contained in at least one functional group selected from the group consisting of -SO3H, -SO3Na, -SO3K, -OSO3H, -OSO3Na, and -OSO3K.

[0018] That is, as one aspect of the present disclosure, An external additive particle comprising a polymer having at least one functional group selected from the group consisting of -SO3H, -SO3Na, -SO3K, -OSO3H, -OSO3Na, and -OSO3K, the polymer has a vinyl polymer portion and a siloxane portion; the ratio of the number of silicon atoms to the total number of carbon atoms, oxygen atoms, and silicon atoms in the external additive particles is 4.0% or more and 25.0% or less, The functional group is preferably contained in the surface region of the external additive particle.

[0019] The presence of a sulfo group or a sulfate group in the surface region of an external additive particle means that when X-ray photoelectron spectroscopy is performed on the surface of the external additive particle, a sulfur atom contained in the functional group is detected.

[0020] Examples of methods for incorporating sulfo groups or salts thereof into the surfaces of polymers and external additives according to the present disclosure include using a radically polymerizable sulfonate, such as sodium p-styrenesulfonate, in the polymer material described below. Also, examples of methods for incorporating sulfate groups or salts thereof into the surfaces of polymers and external additives according to the present disclosure include using a persulfate, such as potassium peroxodisulfate, as a radical polymerization initiator. When potassium peroxodisulfate is used as a radical polymerization initiator during polymer production, -OSOK or -OSOH is introduced at the terminal of the polymer, and a sulfur atom is introduced into the produced polymer.

[0021] <Polymer having a vinyl polymer moiety and a siloxane moiety> The polymers according to the present disclosure have a vinyl polymer portion and a siloxane portion.

[0022] The vinyl polymer portion in the polymer is an organic polymer portion formed by polymerizing a vinyl-based polymerizable monomer. The inclusion of the vinyl polymer portion in the polymer contained in the external additive particles is thought to increase affinity with the resin constituting the toner particles, making it difficult for the external additive particles to separate from the toner particles.

[0023] Furthermore, the polymer contained in the external additive particles contains not only a vinyl polymer portion but also a siloxane portion, which makes the external additive particles containing the polymer according to the present disclosure likely to have sufficient mechanical strength and be resistant to plastic deformation, and therefore the toner to which the external additive particles are externally added can have excellent fluidity.

[0024] In one embodiment of the polymer according to the present disclosure, it is preferable that the polymer is a polymer in which vinyl polymer chains are crosslinked by siloxane bonds. It is believed that the inclusion of such a polymer in the external additive particles increases the mechanical strength of the external additive particles, making them less susceptible to plastic deformation. Similarly, in one embodiment of the polymer according to the present disclosure, it is preferable that the polymer is a polymer having a structure in which molecular chains of vinyl polymers are bonded via siloxane bonds. Furthermore, it is preferable that the polymer according to the present disclosure constitutes the external additive particles.

[0025] Particles having only a polysiloxane skeleton, such as silica particles, have high mechanical strength but low affinity with the resin that constitutes the toner particles, and the fluidity of the toner tends to decrease when continuous image output is performed.

[0026] Furthermore, particles having only an organic polymer skeleton, such as polymethyl methacrylate particles, have low mechanical strength, and therefore, when used as external additive particles, they are likely to undergo plastic deformation or breakage due to mechanical impact in a developing machine, etc. As a result, the toner tends to adhere to various components, making it difficult to obtain a toner with excellent fluidity.

[0027] The method for obtaining the polymer according to the present disclosure can be exemplified by the method of carrying out vinyl polymerization using a vinyl polymerization monomer containing a silicon atom bonded to a hydrolyzable group such as methoxy group, and then carrying out the hydrolysis and polycondensation of this hydrolyzable group to form siloxane bond.In this method, vinyl polymerization is carried out first to form a vinyl polymer chain, and then hydrolysis and polycondensation are carried out to form siloxane bond in this polymer or between these polymers, so that the polymer in which the vinyl polymer chain is crosslinked by siloxane bond can be obtained.

[0028] <The ratio of the number of silicon atoms to the total number of carbon atoms, oxygen atoms, and silicon atoms> The proportion of the number of silicon atoms to the total number of carbon atoms, oxygen atoms, and silicon atoms in the external additive particles is 4.0% or more and 25.0% or less.

[0029] The present inventors believe that the ratio of the number of silicon atoms to the total number of carbon atoms, oxygen atoms, and silicon atoms is an index of the amount of siloxane moieties present in the external additive particles.

[0030] When the above ratio is 4.0% or more, the siloxane moiety is sufficiently present in the external additive particles, which is thought to make the external additive particles less susceptible to plastic deformation, thereby making it easier to obtain a toner with excellent fluidity. Furthermore, when the above ratio is 25.0% or less, the amount of siloxane moiety in the external additive particles is less likely to become excessive, which is thought to make the external additive particles less likely to separate from the toner particles, thereby making it easier to obtain a toner with excellent fluidity. Therefore, the ratio is 25.0% or less, preferably 20.0% or less, more preferably 15.0% or less, and even more preferably 10.0% or less. In other words, the ratio is more preferably 4.0% or more and 10.0% or less. It is also preferable that the ratio is 8.0% or less.

[0031] Furthermore, since a toner having excellent fluidity can be easily obtained, the ratio of the number of carbon atoms in the external additive particles to the number of silicon atoms in the external additive particles is preferably 6.5 or more. More preferably, it is 7.5 or more, and even more preferably, it is 13.5 or more. There is no particular upper limit, but from the viewpoint of toner fluidity, it is preferably 20.0 or less. More preferably, it is 17.0 or less.

[0032] The ratio of the above-mentioned number of atoms can be controlled by adjusting the type and amount of monomer units containing silicon atoms and the type and amount of monomer units not containing silicon atoms when producing the polymer contained in the external additive particles.

[0033] <Monomer units in polymer> The polymer preferably contains a monomer unit represented by the following formula (1), since the ratio of carbon atoms, oxygen atoms, and silicon atoms is likely to fall within the above range and the effects of the present disclosure are likely to be obtained.

[0034] [ka]

[0035] (In formula (1), R 1 is an alkylene group having 1 to 10 carbon atoms, and R' is a hydrogen atom or a methyl group. In this disclosure, SiO N / 2 This means that, of the four valences of a silicon atom, N are bonded to oxygen atoms, and each of the N oxygen atoms is bonded to Si. In other words, each of the N oxygen atoms is treated as a unit in which a siloxane bond (Si-O-Si) is formed.

[0036] In addition, as one embodiment of the polymer according to the present disclosure having a sulfur atom, it is preferable that the polymer has a monomer unit represented by the following formula (S):

[0037] [ka]

[0038] (In formula (S), R S1 ~R S4 are each independently a hydrogen atom or a methyl group, and X is a hydrogen atom or an alkali metal atom. When the polymer contains the above-mentioned monomer unit, the polymer according to the present disclosure contains sulfur atoms, and even after continuous image output, sulfur atoms are likely to be present on the surface of the external additive particles, which can improve the fluidity maintenance of the toner to which the external additive particles containing the polymer are externally added. Examples of the alkali metal atom in the above formula (S) include Na and K. In addition, the position of -SO3X in the above formula (S) is preferably the para position relative to -CH2-CH- in the above formula (S). In addition, R S1 ~R S4 is preferably a hydrogen atom.

[0039] <D50 of external additive particles> In order to ensure that the external additive particles have an appropriate volume average particle size, when the 50% particle size based on the volume distribution of the external additive particles is defined as D50, the D50 is preferably 50 nm or more and 200 nm or less.

[0040] <Method for producing external additive particles> In the production of the external additive particles, it is preferable to carry out a radical polymerization reaction using a compound containing in its molecule both a radically polymerizable group and a hydrolyzable group that forms a siloxane bond by hydrolysis and polycondensation, and then to carry out a hydrolysis reaction and a polycondensation reaction. By carrying out the radical polymerization reaction first, the main skeleton of the polymer contained in the external additive particles becomes a vinyl polymer moiety, which is thought to easily increase affinity with the resin that constitutes the toner, and to easily increase the fluidity of the toner to which the external additive particles are externally added.

[0041] Furthermore, it is preferable to include a radically polymerizable sulfonate in the monomer raw material for the radical polymerization reaction and / or to use a persulfate as a radical polymerization initiator, since this allows sulfur atoms to be incorporated into the surface regions of the polymer and toner particles according to the present disclosure.

[0042] That is, one aspect of the present disclosure is a method for producing external additive particles containing a polymer, the method preferably comprising step (i-1) and step (ii), or step (i-2) and step (ii): (i-1) a step of radically polymerizing a monomer raw material containing a radically polymerizable sulfonate and a compound represented by the following formula (2) to obtain a polymer having a hydrolyzable group in the formula (2): (i-2) a step of radically polymerizing a monomer raw material containing a compound represented by the following formula (2) using a persulfate as a radical polymerization initiator to obtain a polymer having a hydrolyzable group in the formula (2): (ii) a step of hydrolyzing the hydrolyzable groups in the polymer obtained by the step (i-1) or the step (i-2) and carrying out polycondensation to obtain the polymer; R 5 m Six 4-m(2) (In formula (2), X is a hydrolyzable group, and m is an integer of 1 to 3. When m=1, R 5 is a radical polymerizable group having 1 to 20 carbon atoms, When m=2~3, multiple R 5 At least one R 5 is a radical polymerizable group having 1 to 20 carbon atoms, and other R is not a radical polymerizable group. 5 are each independently an alkyl group having 1 to 20 carbon atoms.

[0043] R 5 The number of carbon atoms in the group is more preferably 1 to 15, and even more preferably 1 to 10. Furthermore, m is preferably 1 or 2, and even more preferably 1.

[0044] After the radical polymerization reaction, the hydrolysis reaction of the hydrolyzable group X in the formula (2) and the polycondensation reaction are carried out, thereby obtaining external additive particles containing a polymer in which a vinyl polymer is crosslinked by a siloxane bond. Furthermore, by carrying out hydrolysis and polycondensation after the molecular chain of the vinyl polymer is formed, it is easy to obtain a polymer in which the ratio of the number of silicon atoms is controlled as described above. Furthermore, it is thought that by carrying out the hydrolysis reaction and the polycondensation reaction later, sulfur atoms are easily incorporated into the surface of the external additive particles.

[0045] The hydrolyzable group according to the present disclosure refers to a functional group that is converted to a hydroxy group when hydrolyzed while bonded to a silicon atom, or a hydroxy group. Examples include at least one selected from the group consisting of a hydroxy group, a fluoro group, a chloro group, a bromo group, an iodo group, an alkoxy group, and an acyloxy group. A structure in which such a hydrolyzable group is bonded to a silicon atom is easily hydrolyzed by water, and subsequent polycondensation reactions are likely to occur, making it easy to form a siloxane bond. Preferred alkoxy groups are methoxy groups, ethoxy groups, and propoxy groups, and preferred acyloxy groups are acetoxy groups.

[0046] The hydrolyzable group according to the present disclosure is more preferably a hydroxy group, a methoxy group, an ethoxy group, a propoxy group, or an acetoxy group, and even more preferably a methoxy group or an ethoxy group.

[0047] The radical polymerizable group refers to a substituent having a radically reactive double bond in its structure. Examples include a vinyl group, an acryloxyalkyl group, and a methacryloxyalkyl group. The radical polymerizable group is preferably an acryloxyalkyl group or a methacryloxyalkyl group.

[0048] The radically polymerizable sulfonate is an organic sulfonate compound having the radically polymerizable group described above in the compound.

[0049] Examples of the radical polymerizable sulfonate include the following:

[0050] Sodium p-styrenesulfonate, potassium p-styrenesulfonate, lithium p-styrenesulfonate, magnesium p-styrenesulfonate, calcium p-styrenesulfonate, ammonium p-styrenesulfonate, sodium vinylsulfonate, potassium vinylsulfonate, lithium vinylsulfonate, magnesium vinylsulfonate, calcium vinylsulfonate, ammonium vinylsulfonate, etc. These radical polymerizable sulfonates may be used alone or in combination of two or more.

[0051] Examples of persulfates used as radical polymerization initiators include the following:

[0052] Potassium persulfate, sodium persulfate, ammonium persulfate, etc. These persulfates may be used alone or in combination of two or more.

[0053] From the viewpoint of maintaining the fluidity of the toner, the radical polymerizable sulfonate is preferably contained in an amount of 0.4 to 5.0% by mass, more preferably 0.7 to 1.0% by mass, based on the total mass of the monomer raw materials.

[0054] From the viewpoint of toner fluidity, the compound represented by the above formula (2) is preferably 50 to 80% by mass, more preferably 60 to 75% by mass, based on the total mass of the monomer raw materials.

[0055] <Radical polymerization reaction> The radical polymerization reaction method is preferably an emulsion polymerization method. The emulsion polymerization method is a polymerization method in which a medium such as water, a monomer that is poorly soluble in the medium, and an emulsifier (surfactant) or an ionic comonomer are mixed, and a polymerization initiator that is soluble in the medium is added thereto. The emulsion polymerization method is preferably a soap-free emulsion polymerization method in which polymerization is performed without using a surfactant. The present inventors believe that this is because the soap-free emulsion polymerization method prevents the surfactant from remaining on the surface of the external additive particles, making it easier to control the affinity between the toner particles and the external additive particles.

[0056] Specific examples of the compound represented by the above formula (2), that is, the monomer containing both a radically polymerizable group and a hydrolyzable group, include the following.

[0057] Organotrialkoxysilane compounds such as γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-acryloxypropyltrimethoxysilane, γ-acryloxypropyltriethoxysilane, γ-methacryloxypropyltriacetoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, 1-hexenyltrimethoxysilane, and 1-octenyltrimethoxysilane, organotriacetoxysilane, bis(γ-acryloxypropyl)dimethoxysilane, bis(γ-methacryloxypropyl)dimethoxysilane, γ-methacryloxypropylethyldimethoxysilane, γ-methacryloxypropylethyldiethoxysilane, and γ-acryloxypropyl Diorganodialkoxysilane compounds such as bis(γ-acryloxypropyl)ethoxysilane, γ-acryloxypropylethyldiethoxysilane, etc.; triorganoalkoxysilane compounds such as tris(γ-acryloxypropyl)methoxysilane, tris(γ-acryloxypropyl)ethoxysilane, tris(γ-methacryloxypropyl)methoxysilane, tris(γ-methacryloxypropyl)ethoxysilane, bis(γ-acryloxypropyl)vinylmethoxysilane, bis(γ-methacryloxypropyl)vinylmethoxysilane, γ-acryloxypropyldiethylmethoxysilane, γ-acryloxypropyldiethylethoxysilane, γ-methacryloxypropyldiethylmethoxysilane, γ-methacryloxypropyldiethylethoxysilane, etc.

[0058] Of the above monomers, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-acryloxypropyltrimethoxysilane, γ-acryloxypropyltriethoxysilane, γ-methacryloxypropyltriacetoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, and vinyltriacetoxysilane are more preferred.

[0059] The compound represented by the above formula (2), that is, the monomer containing both a radically polymerizable group and a hydrolyzable group, is preferably a monomer represented by the following formula (3).

[0060] [ka]

[0061] (In formula (3), R 1 is an alkylene group having 1 to 10 carbon atoms, and R 2 , R 3 , and R 4 are each independently either hydrogen, a methyl group, or an ethyl group, and R' is hydrogen or a methyl group. The radical polymerization initiator used in the radical polymerization is not particularly limited, but is preferably at least one compound selected from persulfates, azo compounds, and peroxides, and more preferably persulfates. The amount of the radical polymerization initiator is not particularly limited, but is preferably 0.1 to 10.0 mass% relative to the total mass of the raw material monomers, and more preferably 0.3 to 5.0 mass%. When the amount of the radical polymerization initiator is within the above range, the radical polymerization can proceed sufficiently and the amount of heat generated in the reaction system is less likely to be excessive, which is preferable.

[0062] The temperature during radical polymerization can be appropriately selected depending on the type and amount of the radical polymerization initiator used, and is preferably in the range of 30 to 100°C, more preferably in the range of 50 to 80°C.

[0063] The radical polymerization step, i.e., the above step (i-1) or step (i-2), is preferably a step in which a radical polymerization reaction is carried out under the condition of 6.0≦pH≦8.0. More preferably, it is 6.5≦pH≦7.5. It is believed that when the pH of the reaction system is within the above range, hydrolysis of the hydrolyzable groups and polycondensation reactions are less likely to occur during the radical polymerization reaction. It is believed that carrying out hydrolysis and polycondensation reactions after radical polymerization makes it easier for sulfur atoms with higher polarity to be incorporated into the surface of the external additive particles. Therefore, it is preferable that the radical polymerization reaction be carried out in a buffer solution. The buffer solution is not particularly limited, and any buffer solution exhibiting a near-neutral pH, such as a phosphate buffer solution or an MES buffer solution, may be used.

[0064] Furthermore, in the case of radical polymerization, not only a monomer containing both a radically polymerizable group and a hydrolyzable group but also other monomers having a radically polymerizable group may be used.

[0065] Examples of other monomers include unsaturated carboxylic acids such as acrylic acid and methacrylic acid, unsaturated carboxylic acid esters such as acrylic acid esters, methacrylic acid esters, crotonates, itaconic acid esters, maleates, and fumarates, acrylamides, methacrylamides, aromatic vinyl compounds such as styrene, α-styrene, and divinylbenzene, vinyl esters such as vinyl acetate, and vinyl halide compounds such as vinyl chloride. These monomers may be used alone or in combination. Monomers containing two or more radically polymerizable groups, such as divinylbenzene, trimethylolpropane trimethacrylate, and ethylene glycol dimethacrylate, may also be used.

[0066] <Hydrolysis reaction and polycondensation reaction> Although the methods for the hydrolysis and polycondensation reactions are not particularly limited, it is preferable to carry out the hydrolysis reaction under acidic conditions and the polycondensation reaction under basic conditions. Therefore, it is preferable that the step (ii) includes step A in which the reaction is carried out under conditions of 2.0≦pH≦4.0, and step B, after step A, in which the reaction is carried out under conditions of 10.0≦pH≦12.0.

[0067] Specifically, it is preferable to add a catalyst such as an acid or a base to an emulsion containing particles obtained by radical polymerization, and then perform hydrolysis and polycondensation in that state to obtain polycondensate particles. That is, the above step (ii) is preferably a step of performing the hydrolysis reaction and polycondensation reaction of the hydrolyzable group X in formula (2) after the above step (i-1) or step (i-2) to obtain condensate particles. Alternatively, the particles obtained by radical polymerization may be isolated from the emulsion by filtration, centrifugation, vacuum concentration, or the like, and then a catalyst may be added to perform hydrolysis and polycondensation.

[0068] When carrying out hydrolysis or polycondensation after particle formation by radical polymerization reaction, a catalyst such as acetic acid, hydrochloric acid, ammonia, urea, alkanolamine, tetraalkylammonium hydroxide, alkali metal hydroxide, or alkaline earth metal hydroxide may be used.

[0069] Examples of more preferred catalysts from the viewpoint of further promoting polycondensation include organic titanium compounds such as titanium tetraisopropoxide, titanium tetrabutoxide, and diisopropoxy-bis(acetylacetonate) titanate; organic aluminum compounds such as aluminum triisopropoxide, aluminum tri-sec-butoxide, aluminum trisacetylacetonate, and aluminum isopropoxide-bisacetylacetonate; organic zirconium compounds such as zirconium tetrabutoxide and tetrakis(acetylacetonate)zirconium; organic tin compounds such as dibutyltin diacetate, dibutyltin diethylhexanoate, and dibutyltin dimaleate; and acidic phosphate esters. These may be used alone or in combination of two or more. Among these, at least one selected from the group consisting of organic tin compounds and acidic phosphate esters is preferred.

[0070] The solvent used in producing the external additive particles may contain an organic solvent other than water and the catalyst. Specific examples of the organic solvent include alcohols such as methanol, ethanol, isopropanol, n-butanol, isobutanol, sec-butanol, t-butanol, pentanol, ethylene glycol, propylene glycol, and 1,4-butanediol, ketones such as acetone and methyl ethyl ketone, esters such as ethyl acetate, (cyclo)paraffins such as isooctane and cyclohexane, ethers such as dioxane and diethyl ether, and aromatic hydrocarbons such as benzene and toluene. Two or more of these organic solvents may be mixed and used.

[0071] The hydrolysis reaction and polycondensation reaction can be carried out, for example, by adding an appropriate catalyst to the emulsion prepared by the radical polymerization reaction and stirring at a temperature in the range of 0 to 100°C, preferably 0 to 70°C, for 3 to 24 hours.

[0072] <Post-processing> The particles obtained by carrying out the radical polymerization and hydrolysis-polycondensation as described above are isolated from the slurry by a method such as filtration, centrifugation, vacuum concentration, spray drying, or flash vacuum drying, and then preferably dried at 30 to 100° C., more preferably at 30 to 80° C., and even more preferably at 50 to 70° C. By carrying out such a drying treatment, external additive particles having appropriate charging properties and appropriate mechanical strength are easily obtained.

[0073] From the viewpoint of toner chargeability, it is preferable to treat the surface of the external additive particles obtained by the above production method with a surface treatment agent in order to treat the hydroxyl groups remaining on the surface of the external additive particles and to adjust the amount of negative charge. Examples of the surface treatment agent include silicon compounds such as organoalkoxysilane and hexamethyldisilazane, titanium compounds such as tetrabutyl titanate, and hydrolyzates and condensates thereof.

[0074] The method for the surface treatment is not particularly limited, as long as it can coat the surfaces of the external additive particles with the surface treatment agent. For example, the surface treatment can be carried out by placing the external additive particles in a suitable container, then adding the surface treatment agent, and mixing and contacting them with stirring at room temperature (25°C ± 5°C) to about 100°C for 3 to 24 hours. In this case, the surface treatment can be more uniformly carried out by dissolving the surface treatment agent in a solvent such as methanol and gradually adding this dropwise while mixing and contacting. The amount of surface treatment agent present on the surface of the external additive can be adjusted by appropriately selecting the type of surface treatment agent, the surface treatment time, the particle size of the external additive, and the like. If necessary, the surface-treated object can be washed with, for example, alcohol to obtain an external additive from which unnecessary substances have been removed.

[0075] <Toner> Furthermore, the external additive particles according to the present disclosure are preferably contained on the surface of toner particles. That is, one aspect of the present disclosure is a toner containing toner particles and an external additive on the surface of the toner particles, wherein the external additive is the external additive particle according to the present disclosure.

[0076] The toner particles preferably contain a binder resin, such as a polyester resin, a vinyl resin, an epoxy resin, or a polyurethane resin.

[0077] The binder resin preferably has a glass transition point (Tg) of 45 to 70°C from the viewpoint of storage stability.

[0078] <Method of manufacturing toner particles> The method for producing the toner particles according to the present disclosure is not particularly limited, and for example, a pulverization method or a polymerization method such as an emulsion polymerization method, a suspension polymerization method, or a solution suspension method can be used.

[0079] The pulverization method will now be described. In the pulverization method, first, the binder resin, colorant, wax, charge control agent, etc. that constitute the toner particles are thoroughly mixed using a mixer such as a Henschel mixer or a ball mill. Next, the resulting mixture is melt-kneaded using a thermal kneader such as a twin-screw kneading extruder, a heated roll, a kneader, or an extruder, and then cooled and solidified, followed by pulverization and classification. In this way, the toner particles according to the present disclosure are obtained.

[0080] Examples of kneaders include the following: KRC kneader (manufactured by Kurimoto Iron Works); Buss-Co kneader (manufactured by Buss); TEM type extruder (manufactured by Toshiba Machine Co., Ltd.); TEX twin-screw kneader (manufactured by The Japan Steel Works); PCM kneader (manufactured by Ikegai Iron Works); three-roll mill, mixing roll mill, kneader (manufactured by Inoue Seisakusho); Kneadex (manufactured by Mitsui Mining Co., Ltd.); MS-type pressure kneader, kneader-ruder (manufactured by Nippon Spindle Co., Ltd.); and Banbury mixer (manufactured by Kobe Steel, Ltd.).

[0081] Examples of pulverizers include the following: Counter Jet Mill, Micron Jet, Innomizer (manufactured by Hosokawa Micron Corporation); IDS-type mill, PJM jet pulverizer (manufactured by Nippon Pneumatic Mfg. Co., Ltd.); Cross Jet Mill (manufactured by Kurimoto Iron Works Co., Ltd.); Urmax (manufactured by Nisso Engineering Co., Ltd.); SK Jet-O-Mill (manufactured by Seishin Enterprise Co., Ltd.); Kryptron (manufactured by Kawasaki Heavy Industries, Ltd.); Turbo Mill (manufactured by Turbo Industrial Co., Ltd.); and Super Rotor (manufactured by Nisshin Engineering Co., Ltd.).

[0082] Examples of classifiers include the following: Cruseal, Micron Classifier, and Spedic Classifier (manufactured by Seishin Enterprise Co., Ltd.); Turbo Classifier (manufactured by Nisshin Engineering Co., Ltd.); Micron Separator, Turboplex (ATP), and TSP Separator (manufactured by Hosokawa Micron Corporation); Elbow Jet (manufactured by Nittetsu Mining Co., Ltd.), and Dispersion Separator (manufactured by Nippon Pneumatic Industry Co., Ltd.); and YM Microcut (manufactured by Yaskawa Corporation).

[0083] The suspension polymerization method will be described. In the suspension polymerization method, first, a polymerizable monomer capable of producing a binder resin and various additives, if necessary, are mixed, and the materials are dissolved or dispersed using a disperser to prepare a polymerizable monomer composition. Examples of the various additives include colorants, waxes, charge control agents, polymerization initiators, and chain transfer agents. Examples of dispersers include homogenizers, ball mills, colloid mills, and ultrasonic dispersers. Next, the polymerizable monomer composition is added to an aqueous medium containing poorly water-soluble inorganic fine particles, and droplets of the polymerizable monomer composition are prepared using a high-speed disperser such as a high-speed stirrer or ultrasonic disperser (granulation step). The polymerizable monomer in the droplets is then polymerized to obtain toner particles (polymerization step). The polymerization initiator may be mixed during the preparation of the polymerizable monomer composition, or may be mixed into the polymerizable monomer composition immediately before forming droplets in the aqueous medium. Furthermore, the toner particles may be added in a state of being dissolved in a polymerizable monomer or another solvent, as required, during or after the granulation of the droplets, i.e., immediately before the start of the polymerization reaction. After the polymerizable monomer is polymerized to obtain a binder resin, the resulting mixture may be subjected to a solvent removal treatment as required to obtain a dispersion of toner particles.

[0084] <Method of adding external additives to toner particles> The toner according to the present disclosure can be obtained by mixing toner particles and external additives using a mixer such as a Henschel mixer.

[0085] Examples of mixers include the following: Henschel mixer (manufactured by Mitsui Mining Co., Ltd.); Super mixer (manufactured by Kawata Corporation); Ribocone (manufactured by Okawara Manufacturing Co., Ltd.); Nauta mixer, Turbulizer, Cyclomix (manufactured by Hosokawa Micron Corporation); Spiral pin mixer (manufactured by Pacific Machinery Works Co., Ltd.); and Lödige mixer (manufactured by Matsubo Corporation).

[0086] The toner particles preferably contain, on their surfaces, the above-described external additive particles as well as other external additives, such as those listed below.

[0087] Fluorine-based resin powders such as vinylidene fluoride fine powder and polytetrafluoroethylene fine powder; fine powder silica such as wet-process silica and dry-process silica, fine powder titanium oxide, fine powder alumina, treated silica obtained by surface-treating these with a silane compound, a titanium coupling agent, or silicone oil; oxides such as zinc oxide and tin oxide; double oxides such as strontium titanate, barium titanate, calcium titanate, strontium zirconate, and calcium zirconate; carbonate compounds such as calcium carbonate and magnesium carbonate, etc.

[0088] <Various additives for toner> If necessary, the toner may contain one or more additives selected from colorants, waxes, magnetic materials, charge control agents, etc. Various additives used in the toner will be specifically described below.

[0089] <Magnetic material> The toner may contain magnetic particles and be used as a magnetic toner. In this case, the magnetic particles may also serve as a colorant.

[0090] Examples of magnetic particles contained in the magnetic toner include the following.

[0091] Iron oxides such as magnetite, hematite, and ferrite, metals such as iron, cobalt, and nickel, or alloys and mixtures thereof of these metals with metals such as aluminum, cobalt, copper, lead, magnesium, tin, zinc, antimony, bismuth, calcium, manganese, titanium, tungsten, and vanadium.

[0092] The magnetic particles preferably have an average particle size of 2 μm or less, more preferably 0.05 μm or more and 0.5 μm or less, and the content of the magnetic particles is preferably 20 parts by mass or more and 200 parts by mass or less, more preferably 40 parts by mass or more and 150 parts by mass or less, per 100 parts by mass of the binder resin.

[0093] <Coloring agent> Examples of colorants include the following:

[0094] As a black colorant, for example, carbon black, grafted carbon, or the yellow / magenta / cyan colorants shown below are used to tone the color to black.

[0095] Yellow colorants include compounds typified by condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and allylamide compounds.

[0096] Examples of magenta colorants include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, perylene compounds, etc. Examples of cyan colorants include copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, basic dye lake compounds, etc.

[0097] The colorants may be used alone or in combination, or in the form of a solid solution. The colorants are selected in consideration of hue angle, chroma, brightness, weather resistance, transparency for overhead projectors, and dispersibility in the toner.

[0098] The content of the colorant is preferably 1 part by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the binder resin.

[0099] <Wax> Examples of waxes include the following:

[0100] Low molecular weight polyethylene, low molecular weight polypropylene, polyolefin copolymers, aliphatic hydrocarbon waxes such as polyolefin wax, microcrystalline wax, paraffin wax, and Fischer-Tropsch wax, oxides of aliphatic hydrocarbon waxes such as oxidized polyethylene wax, block copolymers of aliphatic hydrocarbon waxes, and oxides thereof.

[0101] Ester waxes whose main component is fatty acid ester, such as carnauba wax; partially or completely deoxidized fatty acid esters, such as deoxidized carnauba wax.

[0102] <Charge control agent> The charge control agent is not particularly limited, but is preferably an organic metal complex or a chelate compound, such as a monoazo metal complex, an acetylacetone metal complex, or a metal complex or metal salt of an aromatic hydroxycarboxylic acid or an aromatic dicarboxylic acid.

[0103] Specific examples that can be used include Spilon Black TRH, T-77, and T-95 (Hodogaya Chemical Co., Ltd.), and BONTRON (registered trademark) S-34, S-44, S-54, E-84, E-88, and E-89 (Orient Chemical Co., Ltd.). Charge control resins can also be used in combination with the above-mentioned charge control agents.

[0104] <Developer> The toner can be used as a one-component developer, but in order to further improve dot reproducibility and to provide stable images over a long period of time, it may also be mixed with a magnetic carrier and used as a two-component developer.

[0105] As the magnetic carrier, for example, iron with an oxidized surface, iron with an unoxidized surface, nickel, cobalt, manganese, chromium, rare earth metals, and alloys or oxides thereof are preferably used.

[0106] Furthermore, it is preferable that the surface of the magnetic carrier contains or is coated with a styrene-based resin, an acrylic-based resin, a silicone-based resin, a fluorine-based resin, or a polyester.

[0107] <Various measurement methods, etc.> Various measurement methods will be described below.

[0108] <Method for measuring the ratio of the number of sulfur atoms to the total number of carbon atoms, oxygen atoms, silicon atoms, and sulfur atoms on the surface of external additive particles> The ratio of the number of sulfur atoms present in the surface region of the external additive particles is measured by X-ray photoelectron spectroscopy using the following apparatus and measurement conditions. Equipment used: ULVAC-PHI PHI Quantera SXM ·X-ray photoelectron spectrometer measurement conditions: X-ray source Al Kα(1486.6eV) 200μmφ Pass Energy: 140 eV Charge neutralization: Combined use of electron neutralization gun and Ar ion neutralization gun Sweep number: C 20 times, O 20 times, Si 20 times, S 100 times The atomic concentrations (all in atomic %) of carbon atoms, oxygen atoms, silicon atoms, and sulfur atoms present in the surface region of the external additive particles were calculated from the measured peak intensity of each element using relative sensitivity factors provided by ULVAC-PHI, Inc. From these results, the ratio of the number of sulfur atoms to the total number of carbon atoms, oxygen atoms, silicon atoms, and sulfur atoms on the surface of the external additive particles was calculated.

[0109] <Method for measuring the concentration (atomic %) of carbon atoms, oxygen atoms, and silicon atoms in external additive particles> Carbon and oxygen atoms The concentrations (atomic %) of carbon atoms and oxygen atoms present in the external additive particles are calculated using elemental analysis by combustion. The device for elemental analysis is shown below.

[0110] Equipment used: PerkinElmer 2400II fully automatic elemental analyzer Silicon atoms The concentration (atomic %) of silicon atoms present in the external additive particles is measured by elemental analysis using ICP-AES by alkali fusion. The ICP-AES device is shown below.

[0111] Equipment used: Shimadzu ICPS-8100 The obtained composition ratio is converted to mol%, and the converted value is used to calculate the ratio of the number of silicon atoms to the total number of carbon atoms, oxygen atoms, and silicon atoms in the external additive particles. Similarly, the ratio of the number of carbon atoms to the number of silicon atoms in the external additive particles is calculated.

[0112] <Confirmation of vinyl polymer moieties and siloxane moieties in the polymer> The presence of vinyl polymer moieties in a polymer can be confirmed by subjecting the polymer to pyrolysis GC / MS and identifying the monomer species produced by pyrolysis.

[0113] In the present disclosure, the pyrolysis GC / MS equipment used to confirm whether a polymer contains a vinyl polymer moiety was a combination of the following equipment. Agilent 7890A, 5975C (Agilent Technologies) PY-2020iD (Frontier Labs) In addition, solid-state NMR analysis and IR analysis can also be used in combination with pyrolysis GC / MS.

[0114] In addition, the presence of siloxane moieties in the polymer means that the polymer 29 In the Si-NMR measurement, SiO 4 / 2 (Q) units, SiO 3 / 2 (T) units, SiO 2 / 2 (D) unit, SiO 1 / 2 This can be confirmed by the presence of at least one of the (M) units. 29 In the Si-NMR measurement, SiO 4 / 2 If (Q) units are present, they will appear around -105 ppm to -118 ppm in the above spectrum, and SiO 3 / 2 When (T) units are present, peaks appear around -64 ppm to -74 ppm or -94 ppm to -104 ppm. 2 / 2 If (D) units are present, a peak appears around -13 ppm to -25 ppm, and SiO 1 / 2 When (M) units are present, a peak appears around 8.5 ppm.

[0115] In the present disclosure, the solid-state NMR apparatus used to confirm whether or not a siloxane moiety is contained in a polymer is Avance III (manufactured by Bruker).

[0116] <Measuring method for the 50% particle size (D50) of a particle sample based on its volume distribution> The 50% particle size (D50) of the volume distribution standard of the fine particle sample is measured using a dynamic light scattering particle size distribution analyzer Nanotrac UPA-EX150 (manufactured by Nikkiso). Specifically, the range is set to 0.001 μm to 10 μm, and the measurement is performed according to the following procedure.

[0117] To prevent the sample from agglomerating, a dispersion of the sample is placed in an aqueous solution containing Family Fresh (Kao Corporation) and stirred. After stirring, the sample is poured into the above-mentioned device and measured twice to obtain the average value.

[0118] The measurement conditions are as follows: measurement time is 30 seconds, the refractive index of the sample particles is 1.49, the dispersion medium is water, and the refractive index of the dispersion medium is 1.33.

[0119] The volume particle size distribution of the measurement sample is measured, and the particle size at which the cumulative volume from the small particle diameter side in the cumulative volume distribution is 50% is defined as the 50% particle size (D50) of the volume distribution standard for each microparticle. [Example]

[0120] The present disclosure will be described in detail below with reference to examples, but the present disclosure is not limited to these examples. Unless otherwise specified, "parts" and "%" mean "parts by mass" and "% by mass", respectively.

[0121] The respective measurement results in the examples were obtained by the measurement methods described above.

[0122] <External Additive 1 Manufacturing Example> The following materials were placed in a glass reactor equipped with a thermometer, a reflux condenser, a nitrogen gas inlet tube, and a stirrer. Phosphate buffer solution (pH = 7.0, prepared using sodium dihydrogen phosphate dihydrate (Kishida Chemical Co., Ltd.) and disodium hydrogen phosphate dodecahydrate (Kishida Chemical Co., Ltd.)) 200 parts Sulfur atom source: 0.13 parts sodium p-styrenesulfonate (Kishida Chemical Co., Ltd.) Monomer having a radical polymerizable group and a hydrolyzable group: 11.0 parts of 3-(trimethoxysilyl)propyl methacrylate (Tokyo Chemical Industry Co., Ltd.) Non-hydrolyzable monomer: styrene (Tokyo Chemical Industry Co., Ltd.) 4.7 parts Next, the mixture was heated to 65-70°C while passing nitrogen gas through it, and after stirring for 30 minutes, 0.51 parts of potassium peroxodisulfate (Kishida Chemical Co., Ltd.) was added as an initiator. Stirring was continued for 6 hours to obtain a particle emulsion. To the obtained particle emulsion, acetic acid (Kishida Chemical Co., Ltd.) was added to adjust the pH of the emulsion to 3.0, and then the mixture was stirred at 50°C for 3 hours. Next, to perform an ammonia treatment, 28% by mass ammonia water (Kishida Chemical Co., Ltd.) was added while maintaining the emulsion temperature at 50°C to adjust the pH of the emulsion to 11.0, and the mixture was stirred for another 3 hours to hydrolyze the hydrolyzable groups contained in the particles and polycondensate. Ultrafiltration was then performed to remove excess solute, and concentration / filtration was repeated a total of five times to obtain polymer particles.

[0123] For the polymer particles, 29 Si-NMR measurement and pyrolysis GC / MS confirmed that the polymer particles contained vinyl polymer moieties and siloxane moieties. 27.0 parts of 1,1,1,3,3,3-hexamethyldisilazane (Kishida Chemical Co., Ltd.) was added as a hydrophobic treatment agent to the resulting polymer particles, and the mixture was stirred at 50°C for 24 hours.

[0124] Thereafter, the mixture was dried by spray drying to obtain an external additive 1 having a volume distribution standard 50% particle size (hereinafter referred to as D50) of 130 nm. The physical properties of the external additive 1 are shown in Table 2.

[0125] <Production Examples of External Additives 2 to 10 and 12 to 14> External additives 2 to 10 and 12 to 14 were obtained in the same manner as in the production example of external additive 1, except that the types and amounts of the monomers and sulfur atom sources used were changed as shown in Table 1. The physical properties of external additives 2 to 10 and 12 to 14 are shown in Table 2.

[0126] <Production example of external additive 11> External additive 11 having a D50 of 71 nm was obtained in the same manner as in the production example for external additive 1, except that the types and amounts of monomers used were changed as shown in Table 1 and the step of adding acetic acid in the acetic acid treatment, stirring at 50°C for 3 hours, and then adding 28% by mass of aqueous ammonia was not performed. The physical properties of external additive 11 are shown in Table 2.

[0127] <Production example of external additive 15> The following materials were placed in a glass reactor equipped with a thermometer, a reflux condenser, a nitrogen gas inlet tube, and a stirrer. 200 parts deionized water Sulfur atom source: 0.13 parts sodium p-styrenesulfonate Non-hydrolyzable monomer: butyl methacrylate (Tokyo Chemical Industry Co., Ltd.) 6.3 parts, and styrene 4.7 parts Next, the mixture was heated to 65-70°C while passing nitrogen gas through it, and after stirring for 30 minutes, 0.51 parts of potassium peroxodisulfate was added as an initiator, and stirring was continued for 6 hours to obtain an emulsion of particles. Ultrafiltration was performed to remove excess solutes from the obtained emulsion, and concentration / filtration was repeated a total of 5 times to obtain polymer particles. The polymer particles were 29 Si-NMR measurement and pyrolysis GC / MS confirmed that the polymer particles contained vinyl polymer moieties but no siloxane moieties.

[0128] The obtained polymer particles were dried by spray drying to obtain external additive 15. The physical properties of external additive 15 are shown in Table 2.

[0129] <Production example of external additive 16> External Additive 16 was obtained by the same procedure as in the production example for External Additive 15, except that 0.18 parts of sodium dodecyl sulfate was used instead of sodium p-styrenesulfonate. The physical properties of External Additive 16 are shown in Table 2.

[0130] <Production example of external additive 17> External Additive 17 was obtained by the same procedure as in the production example of External Additive 1, except that sodium p-styrenesulfonate was changed to 0.14 parts of sodium dodecanoate and the initiator used was changed from 0.51 parts of potassium peroxodisulfate to 0.51 parts of 2,2'-azobis(2-methylpropionamidine) dihydrochloride (V-50, manufactured by Tokyo Chemical Industry Co., Ltd.). The physical properties of External Additive 17 are shown in Table 2.

[0131] <Production example of external additive 18> At room temperature, a solution prepared by mixing the following materials was added to a solution prepared by mixing 46.7 parts of 28% by mass aqueous ammonia and 2114 parts of deionized water, and hydrolysis and polycondensation of 3-(trimethoxysilyl)propyl methacrylate was carried out. 22.1 parts 3-(trimethoxysilyl)propyl methacrylate Methanol (Kishida Chemical Co., Ltd.) 73.7 parts Initiator: 2,2'-azobis(2,4-dimethylvaleronitrile) (V-65, manufactured by Tokyo Chemical Industry Co., Ltd.) 0.12 parts Next, the mixture was heated to 70-75°C while passing nitrogen gas through it, and stirred for 2 hours to carry out radical polymerization. After that, ultrafiltration was carried out to remove excess solute, and concentration / filtration was repeated a total of five times to obtain polymer particles. 29 Si-NMR measurement and pyrolysis GC / MS confirmed that the polymer particles contained vinyl polymer moieties and siloxane moieties.

[0132] The obtained polymer particles were dried by spray drying to obtain external additive 18. The physical properties of external additive 18 are shown in Table 2.

[0133] [Table 1]

[0134] The abbreviations in Table 1 are as follows: MA-TMSP: 3-(trimethoxysilyl)propyl methacrylate MA-TESP: 3-(triethoxysilyl)propyl methacrylate AA-TMSP: 3-(trimethoxysilyl)propyl acrylate VTMS: vinyltrimethoxysilane MA-CDMSP: 3-(chlorodimethylsilyl)propyl methacrylate MAB: butyl methacrylate St: styrene DSS: sodium bis(2-ethylhexyl) sulfosuccinate 4-VBANa: sodium 4-vinylbenzoate KPS: potassium peroxodisulfate V-50: 2,2'-Azobis(2-methylpropionamidine) dihydrochloride V-65: 2,2'-azobis(2,4-dimethylvaleronitrile) *4-VBANa does not contain sulfur atoms, but is listed in the sulfur atom source column.

[0135] [Table 2]

[0136] In Table 2, S / (C+O+Si+S) is the ratio of the number of sulfur atoms to the total number of carbon atoms, oxygen atoms, silicon atoms, and sulfur atoms on the surface of the external additive particle. Si / (C+O+Si) is the ratio of the number of silicon atoms to the total number of carbon atoms, oxygen atoms, and silicon atoms in the external additive particle, and C / Si is the ratio of the number of carbon atoms to the number of silicon atoms in the external additive particle.

[0137] The inventors speculate that the sulfur atom source used in the production examples of external additives 12, 13, and 16 does not bond to the polymer in the external additive particles and is therefore washed away from the surface of the external additive particles during the ultrafiltration process. However, the inventors believe that potassium peroxodisulfate used as a polymerization initiator introduces -OSO3K or -OSO3H into the polymer in the external additive particles, resulting in the detection of sulfur atoms on the surface of the external additive particles.

[0138] <Production Example of Toner Particle 1> The following materials were premixed in a Henschel mixer, and then melt-kneaded using a twin-screw extruder (product name: PCM-30, manufactured by Ikegai Iron Works Co., Ltd.) with the temperature set so that the melt temperature at the discharge outlet would be 150°C, to obtain a kneaded material. Amorphous polyester (propylene oxide adduct of bisphenol A / terephthalic acid = 50 / 50, number average molecular weight: 3000, acid value: 12) 100 parts Magnetic iron oxide particles 75 parts Fischer-Tropsch wax (Sasol C105, melting point: 105°C) 2 parts Charge control agent (Hodogaya Chemical Co., Ltd., T-77) 2 parts The resulting kneaded product was cooled, coarsely pulverized with a hammer mill, and then finely pulverized with a pulverizer (product name: Turbo Mill T250, manufactured by Turbo Kogyo Co., Ltd.) to obtain a finely pulverized powder. The finely pulverized powder obtained was classified with a multi-division classifier utilizing the Coanda effect to obtain toner particles 1 having a weight average particle size of 7.2 μm.

[0139] <Toner 1 manufacturing example> The external additive was added to the toner particles 1 in a dry manner. 100 parts of the toner particles 1, 3 parts of the external additive 1, and 1.5 parts of fumed silica (BET specific surface area: 200 m) were added to a Henschel mixer. 2 / g) was added and externally mixed in. Thereafter, the mixture was sieved through a mesh with an opening of 150 μm, and toner 1 in which external additive 1 was externally added to toner particles 1 was obtained.

[0140] <Production examples of toners 2 to 18> Toners 2 to 18 were obtained in the same manner as in the production example of Toner 1, except that the external additives added to Toner Particle 1 were changed to External Additives 2 to 18, respectively.

[0141] Example 1 Toner 1 was used to carry out the following evaluations.

[0142] <Evaluation of toner fluidity> The fluidity of the toner was measured by the following method.

[0143] First, using a powder tester (PT-X, manufactured by Hosokawa Micron Corporation), 3 g of toner 1 was sieved for 10 seconds through sieves (plain woven wire mesh, JIS Z8801-1 standard) with openings of 150 μm, 100 μm, and 45 μm, while the sieves were vibrated at a vibration intensity of 4.0. The fluidity of the toner was evaluated using the fluidity index (%) given by the following formula, where A is the amount of toner remaining on the 150 μm sieve, B is the amount of toner remaining on the 100 μm sieve, and C is the amount of toner remaining on the 45 μm sieve. The evaluation results are shown in Table 3. In this evaluation, a smaller fluidity index value indicates better toner fluidity.

[0144] Fluidity index (%) = [(A + 0.6 × B + 0.2 × C) / measured sample mass] × 100 <Evaluation of Toner Fluidity Maintenance> The fluidity maintenance property of the toner was evaluated after the above evaluations.

[0145] An HP LaserJet Enterprise M609dn (manufactured by HP) was used as the image forming apparatus, and Toner 1 was placed in a cartridge, and 5,000 images were output under the following conditions. ·Paper: GFC-081 (81.0g / m 2 )(Canon Marketing Japan Inc.) Toner coverage on paper: 0.35mg / cm 2 Process speed: 377 mm / sec Thereafter, the residual toner in the cartridge was removed, and the fluidity index was calculated for the residual toner, and this value was used as the fluidity index after durability testing. The fluidity index obtained in the evaluation of the toner fluidity described above was used as the fluidity index before durability testing to calculate the rate of change shown in the following formula, and this value was used to evaluate the fluidity maintenance property of the toner.

[0146] Fluctuation rate (%) = (liquidity index after endurance - liquidity index before endurance) / liquidity index before endurance × 100 A rate of change of 100% or less was determined to be one in which the effects of the present disclosure were achieved.

[0147] <Evaluation of external additive particle crushing and detachment from toner particles> The crushing of the external additive particles and their detachment from the toner particles were evaluated after the above evaluation of the toner fluidity maintenance property was carried out.

[0148] After the 5,000 images were output, the remaining toner 1 in the cartridge was removed, and the surface of the removed toner 1 was observed using a scanning electron microscope (S-4800, manufactured by Hitachi High-Technologies Corporation), and an SEM image was obtained. In the obtained image, if crushed deposits were observed on the surface of the toner, it was judged as having been crushed, and if depressions from which external additive particles had been detached were observed on the surface of the toner, it was judged as having been detached.

[0149] <Examples 2 to 14, Comparative Examples 1 to 4> Toners 2 to 18 were used to carry out the same evaluation as in Example 1. The evaluation results are shown in Table 3.

[0150] [Table 3]

Claims

1. A toner comprising toner particles and external additive particles on the surfaces of the toner particles, the external additive particles contain a polymer having a sulfur atom, the polymer is a polymer in which vinyl polymer chains are crosslinked by siloxane bonds, the ratio of the number of silicon atoms to the total number of carbon atoms, oxygen atoms, and silicon atoms in the external additive particles is 4.0% or more and 10.0% or less; The toner is characterized in that sulfur atoms are detected when the surface of the external additive particles is subjected to X-ray photoelectron spectroscopy.

2. A toner comprising toner particles and external additive particles on the surfaces of the toner particles, the external additive particles contain a polymer having a sulfur atom, the polymer has a vinyl polymer portion and a siloxane portion; the ratio of the number of silicon atoms to the total number of carbon atoms, oxygen atoms, and silicon atoms in the external additive particles is 4.0% or more and 10.0% or less; When X-ray photoelectron spectroscopy is performed on the surface of the external additive particle, sulfur atoms are detected, and the ratio of the number of sulfur atoms to the total number of carbon atoms, oxygen atoms, silicon atoms, and sulfur atoms is 0.10% or more and 0.50% or less.

3. 3. The toner according to claim 1, wherein the polymer contains a monomer unit represented by the following formula (1): 【Chemical 1】 (In formula (1), R １ is an alkylene group having 1 to 10 carbon atoms, and R' is a hydrogen atom or a methyl group.

4. 3. The toner according to claim 1, wherein the ratio of the number of carbon atoms in the external additive particles to the number of silicon atoms in the external additive particles is 6.5 or more.

5. When the 50% particle size of the external additive particles based on the volume distribution is defined as D50, 3. The toner according to claim 1, wherein the D50 is 50 nm or more and 200 nm or less.

6. The polymer is -SO ３ H, -SO ３ Na, -SO ３ K, -OSO ３ H, -OSO ３ Na, and -OSO ３ 3. The toner according to claim 1, wherein the toner has at least one functional group selected from the group consisting of:

7. 3. The toner according to claim 1, wherein the polymer has a monomer unit represented by the following formula (S): 【Chemistry 2】 (In formula (S), R Ｓ１ ~R Ｓ４ are each independently a hydrogen atom or a methyl group, and X is a hydrogen atom or an alkali metal atom.

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