JP7731731B2 - External additive particles, method for producing external additive particles, and toner - Google Patents

Description

This disclosure relates to external additive particles, a method for producing external additive particles, and toner.

In recent years, there has been a demand for even faster speeds and longer life for image forming devices that use electrophotography. In response to these demands, toners with excellent fluidity and developability are being investigated, as they must be stress-resistant enough to withstand long periods of friction within the developing device, and also have the ability to obtain high image quality even during high-speed printing.

Patent Document 1 discloses that the fluidity and other properties of toner can be improved by incorporating a toner additive having an organic polymer skeleton and a polysiloxane skeleton into the toner.

Japanese Patent Application Publication No. 8-202071

One aspect of the present disclosure is to provide external additive particles that can produce toner that has excellent fluidity and whose charge amount is less likely to change depending on the environment, even when continuous image output is performed.

Another aspect of the present disclosure is directed to providing a toner to which the external additive particles of the present disclosure have been externally added.

Another aspect of the present disclosure is directed to providing a method for producing external additive particles according to the present disclosure.

According to one aspect of the present disclosure, there is provided an external additive particle comprising a polymer having a vinyl polymer portion and a polysiloxane 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 polymer has a structure represented by the following formula (1):

(In formula (1),
R' is a hydrogen atom or a methyl group;
L2 is a polysiloxane moiety containing SiO _3/2 units and SiO _2/2 units, and at least one silicon atom constituting the SiO _2/2 units has two alkyl groups having 1 to 10 carbon atoms bonded to the silicon atom;
L1 is *-COOR ¹ -**, *-CH ₂ -**, or *-COOR ¹ -SiR ² ₂ -O-**, R ¹ is an alkylene group having 1 to 10 carbon atoms, R ² is each independently an alkyl group having 1 to 10 carbon atoms, * is a bonding site to the carbon atom bonded to R ^′ in formula (1), and ** is a bonding site to the silicon atom constituting the SiO _3/2 unit contained in L2).

According to another aspect of the present disclosure, there is provided a toner comprising toner particles and an external additive on the surfaces of the toner particles,
A toner is provided in which the external additive is the external additive particles according to the present disclosure.

According to another aspect of the present disclosure, there is provided a method for producing external additive particles containing a polymer, the method comprising:
The manufacturing method comprises:
(i) performing a radical polymerization reaction of a monomer raw material containing at least one compound selected from the group consisting of a compound represented by the following formula (4), a compound represented by the following formula (5), and a compound represented by the following formula (6), to obtain a polymer having a hydrolyzable group X;

(In formulas (4) to (6), X ¹ to X ⁷ each independently represent a hydrolyzable group X, and R' each independently represent a hydrogen atom or a methyl group. R ⁵ and R ⁶ each independently represent an alkylene group having 1 to 10 carbon atoms, and R ⁷ and R ⁸ each independently represent an alkyl group having 1 to 10 carbon atoms.)
(ii) adding the following polysiloxane A having a hydrolyzable group Y (Polysiloxane A: a polysiloxane containing SiO _2/2 units, the SiO _2/2 units being at least SiO _2/2 units represented by the following formula (7) and SiO _2/2 units represented by the following formula (8)

(In formula (7), R ⁹ is an alkyl group having 1 to 10 carbon atoms, R ¹⁰ is an alkylene group having 1 to 10 carbon atoms, and Y is a hydrolyzable group. In formula (8), R ¹¹ and R ¹² are each independently an alkyl group having 1 to 10 carbon atoms.)
(iii) performing a hydrolysis reaction and a polycondensation reaction between the hydrolyzable group X of the polymer and the hydrolyzable group Y of the polysiloxane A to obtain particles containing a polymer in which the polymer and the polysiloxane A are bonded by a siloxane bond;
Including,
Method for producing external additive particles.

One aspect of the present disclosure provides external additive particles that can produce toner that has excellent fluidity and whose charge amount is less likely to change depending on the environment, even when continuous image output is performed.

Furthermore, according to another aspect of the present disclosure, a toner to which the external additive particles according to the present disclosure are externally added can be provided.

Furthermore, according to another aspect of the present disclosure, a method for producing external additive particles according to the present disclosure can be provided.

When a numerical range is expressed as "xx or more and xx or less" or "xx to xx," it means that the numerical range includes the endpoints, which are the lower and upper limits, unless otherwise specified. When a numerical range is stated in stages, the upper and lower limits of each numerical range can be combined in any way.

In the present disclosure, SiO _N/2 is treated as a unit in which, 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, it is treated as a unit in which each of the N oxygen atoms forms a siloxane bond (Si—O—Si).

<Background to the invention>
The technology disclosed in Patent Document 1 certainly provides a toner additive that can impart excellent fluidity. The inventors speculate that this is because the polysiloxane skeleton increases the mechanical strength of the particles, and the organic polymer skeleton increases affinity with the binder resin of the toner, making it less likely to separate from the toner particles. After further investigation of the above additive, they found that controlling the proportion of silicon atoms in the external additive particles makes it easier to improve the fluidity of the toner.

However, the inventors discovered that when continuous image output is performed using toner containing the above-mentioned external additive particles with a controlled silicon atom ratio, the difference in toner charge amount tends to be large when used in a room-temperature, low-humidity environment and when used in a high-temperature, high-humidity environment. The inventors speculate that this is because the ease of friction between the above-mentioned external additive particles containing polysiloxane moieties and the toner particles is easily affected by humidity, which in turn makes the toner's triboelectric charge amount more likely to change. From the perspective of achieving stable, high-quality image output in a variety of environments, it is preferable for the toner's charge amount to change little depending on the environment. Therefore, they recognized that further improvements to the above-mentioned external additive particles are necessary.

Based on the above considerations, the inventors investigated external additive particles that can produce toner with excellent fluidity and whose charge amount is less likely to change depending on the environment. As a result, they discovered that incorporating a structure represented by the following formula (1) into the polymer contained in the external additive particles is effective in realizing toner with the above-mentioned properties.

(In formula (1),
R' is a hydrogen atom or a methyl group;
L2 is a polysiloxane moiety containing an SiO _3/2 unit and an SiO _2/2 unit in which two alkyl groups having 1 to 10 carbon atoms are bonded to a silicon atom,
L1 is *-COOR ¹ -**, *-CH ₂ -**, or *-COOR ¹ -SiR ² ₂ -O-**, R ¹ is an alkylene group having 1 to 10 carbon atoms, each R ² is independently an alkyl group having 1 to 10 carbon atoms, * is a bonding site to the carbon atom bonded to R ^′ in formula (1), and ** is a bonding site to the silicon atom constituting the SiO _3/2 unit contained in L2.
The present inventors speculate that the inclusion of a polymer having the above structure in an external additive particle makes the external additive particle less susceptible to the effects of humidity. This is thought to be because the polysiloxane portion (L2) in the above structure contains an SiO _2/2 unit in which two alkyl groups having 1 to 10 carbon atoms are bonded, which makes the polysiloxane portion more likely to exhibit hydrophobic properties. As a result, the present inventors speculate that a toner to which the external additive particle is externally added will have less change in charge amount depending on the environment (especially humidity).

Each component is explained in detail below.

<Polymer having a vinyl polymer portion and a polysiloxane portion>
The polymer contained in the external additive particles has a vinyl polymer portion and a polysiloxane portion.

The vinyl polymer portion of the polymer is an organic polymer skeleton formed by the polymerization of vinyl-based polymerizable monomers. The presence of this vinyl polymer skeleton is thought to increase affinity with the resin that makes up the toner particles, making it difficult for the external additive particles to separate from the toner particles.

Furthermore, the polymer contained in the external additive particles contains not only vinyl polymer moieties but also siloxane moieties. This makes it easier for external additive particles containing the polymer according to the present disclosure to have sufficient mechanical strength and to be external additive particles that are less susceptible to plastic deformation, and therefore toner to which such external additive particles are externally added can have excellent fluidity.

Particles that have only a polysiloxane skeleton, such as silica particles, have high mechanical strength but low affinity with the resin that makes up the toner particles, which can cause them to separate from the toner particles and reduce the fluidity of the toner.

Furthermore, particles that have 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 impacts inside developing machines, etc. As a result, the toner may be more likely to adhere to various components, which can reduce the fluidity of the toner.

<Proportion of the number of silicon atoms to the total number of carbon atoms, oxygen atoms, and silicon atoms>
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 inventors believe that the above ratio is an indicator of how much siloxane moiety is present in the external additive particles.

When the above ratio is 4.0% or more, sufficient siloxane moieties are present in the external additive particles, which is thought to make the external additive particles less susceptible to plastic deformation, making it easier to obtain toner with excellent fluidity. Furthermore, when the ratio is 25.0% or less, the amount of siloxane moieties in the external additive particles is less likely to become excessive, and a sufficient amount of vinyl polymer moieties is contained in the external additive particles, making it harder for the external additive particles to separate from the toner particles, making it easier to obtain 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, it is even more preferable that the above ratio is 4.0% or more and 10.0% or less.

The ratio of the above atomic numbers 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. It can also be controlled by the order of the radical polymerization reaction, hydrolysis reaction, and polycondensation reaction when producing the polymer contained in the external additive particles.

<Structure in polymer>
The polymer according to the present disclosure has a structure represented by the following formula (1):

(In formula (1),
R' is a hydrogen atom or a methyl group;
L2 is a polysiloxane moiety containing SiO _3/2 units and SiO _2/2 units, and at least one silicon atom constituting the SiO _2/2 units has two alkyl groups having 1 to 10 carbon atoms bonded to the silicon atom;
L1 is *-COOR ¹ -**, *-CH ₂ -**, or *-COOR ¹ -SiR ² ₂ -O-**, R ¹ is an alkylene group having 1 to 10 carbon atoms, R ² is each independently an alkyl group having 1 to 10 carbon atoms, * is a bonding site to the carbon atom bonded to R ^′ in formula (1), and ** is a bonding site to the silicon atom constituting the SiO _3/2 unit contained in L2).

As described above, it is believed that the inclusion of SiO _2/2 units in which two alkyl groups having 1 to 10 carbon atoms are bonded to a silicon atom in the polysiloxane portion of the structure reduces environmentally dependent change in charge quantity in a toner to which external additive particles according to the present disclosure are externally added. Furthermore, the inventors believe that the inclusion of SiO _3/2 units in the polysiloxane portion and the presence of three-dimensionally bonded portions in the polysiloxane portion make it easier for the polymer to have sufficient mechanical strength, making it easier for the external additive particles to be less susceptible to plastic deformation.

The SiO _2/2 unit contained in L2 is preferably an SiO 2/2 unit in which two alkyl groups having 1 to 5 carbon atoms are bonded to a silicon atom, and more preferably an SiO _2/2 unit in which two alkyl groups having 1 to 3 carbon atoms are bonded to a silicon atom. Also, an SiO _2/2 unit in which at least one of the two alkyl groups bonded to the silicon atom is a methyl group is more preferred, and even more preferably an SiO _2/2 unit in _which two methyl groups are bonded to the silicon atom.

The ^R1 is preferably an alkylene group having 1 to 5 carbon atoms. Each of the ^R2 is preferably an alkyl group having 1 to 5 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms. The L1 is preferably * ^-COOR1 -**.

It is also preferred that at least one silicon atom constituting the SiO _3/2 unit contained in L2 (polysiloxane portion) is bonded to a group represented by the following formula (2).
R ³ -SiO _2/2 -R ⁴ -*...(2)
(In the above formula (2), ^R3 is an alkyl group having 1 to 6 carbon atoms, ^R4 is an alkylene group having 1 to 10 carbon atoms, and * indicates the bonding site with the silicon atom.)

The present inventors speculate that the polysiloxane portion having the SiO _3/2 unit represented by formula (2) reduces the environmentally dependent change in the charge amount of the toner and increases the mechanical strength of the external additive particles.

^R3 is more preferably an alkyl group having 1 to 3 carbon atoms, and even more preferably a methyl group. ^R4 is more preferably an alkylene group having 1 to 5 carbon atoms, and even more preferably an alkylene group having 1 to 3 carbon atoms.

Furthermore, from the viewpoint of environmentally dependent changes in the charge amount of the toner, it is preferable that an alkyl group having 1 to 3 carbon atoms and a group represented by the following formula (3) are bonded to at least one silicon atom constituting the SiO _2/2 unit contained in L2 (polysiloxane portion).
(R ³² )(R ³³ )(Si(R ³⁴ ) ₃ )Si-R ³¹ -※※...(3)
(In the above formula (3), R ³² , R ³³ , and R ³⁴ are each independently an alkyl group having 1 to 3 carbon atoms, R ³¹ is an alkylene group having 1 to 3 carbon atoms, and ** is a bonding site to the silicon atom.)

One method for obtaining the polymer according to the present disclosure is to perform vinyl polymerization using a vinyl monomer containing a silicon atom bonded to a hydrolyzable group such as an alkoxy group, followed by hydrolysis of the hydrolyzable group and polycondensation to form a siloxane bond. In this method, vinyl polymerization is first performed to form a polymer chain, and then hydrolysis and polycondensation form siloxane bonds within or between the polymers, resulting in a polymer in which the vinyl polymer is crosslinked by siloxane bonds. In other words, one preferred aspect of the polymer according to the present disclosure is a polymer in which the vinyl polymer is crosslinked by siloxane bonds. It is believed that including this polymer in the external additive particles increases the mechanical strength of the external additive particles and makes them less susceptible to plastic deformation.

Furthermore, in the above method, by adding the polysiloxane described below during the hydrolysis and condensation polymerization reaction, the polysiloxane moiety (L2) according to the present disclosure is introduced into the polymer.

Furthermore, since it is believed that the effects of the present disclosure can be more easily achieved, it is preferable that the polymer according to the present disclosure be contained in an amount of 70% by mass or more relative to the mass of the external additive particles. It is more preferable that the amount be 80% by mass or more, and even more preferable that the amount be 90% by mass or more.

<D50 of external additive particles>
In order to appropriately control the adhesive force of the external additive particles to the toner, when the 50% particle size of the external additive particles based on volume distribution is defined as D50, it is preferable that D50 is 50 nm or more and 200 nm or less.

<Method of manufacturing external additive particles>
During the production of the external additive particles, it is preferable to carry out a radical polymerization reaction using a compound containing both a radically polymerizable group and a hydrolyzable group that forms a siloxane bond by hydrolysis and polycondensation in the molecule. Then, it is preferable to add a polysiloxane having an SiO _2/2 unit represented by the following formula (7) and an SiO _2/2 unit represented by the following formula (8) to carry out a hydrolysis reaction of the hydrolyzable group and a polycondensation reaction to obtain polycondensate particles. 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 increase affinity with the resin that constitutes the toner, and to increase the fluidity of the toner to which the external additive particles are externally added. In the present disclosure, as a monomer containing both a radically polymerizable group and a hydrolyzable group in the molecule, at least one compound selected from the group consisting of a compound represented by the following formula (4), a compound represented by the following formula (5), and a compound represented by the following formula (6) is cited.

That is, one aspect of the present disclosure is a method for producing external additive particles containing a polymer, the method comprising:
The manufacturing method comprises:
(i) performing a radical polymerization reaction of a monomer raw material containing at least one compound selected from the group consisting of a compound represented by the following formula (4), a compound represented by the following formula (5), and a compound represented by the following formula (6), to obtain a polymer having a hydrolyzable group X;

(In formulas (4) to (6), X ¹ to X ⁷ each independently represent a hydrolyzable group X, and R' each independently represent a hydrogen atom or a methyl group. R ⁵ and R ⁶ each independently represent an alkylene group having 1 to 10 carbon atoms, and R ⁷ and R ⁸ each independently represent an alkyl group having 1 to 10 carbon atoms.)
(ii) adding the following polysiloxane A having a hydrolyzable group Y (Polysiloxane A: a polysiloxane containing SiO _2/2 units, the SiO _2/2 units being at least SiO _2/2 units represented by the following formula (7) and SiO _2/2 units represented by the following formula (8)

(In formula (7), R ⁹ is an alkyl group having 1 to 10 carbon atoms, R ¹⁰ is an alkylene group having 1 to 10 carbon atoms, and Y is a hydrolyzable group. In formula (8), R ¹¹ and R ¹² are each independently an alkyl group having 1 to 10 carbon atoms.)
(iii) performing a hydrolysis reaction and a polycondensation reaction between the hydrolyzable group X of the polymer and the hydrolyzable group Y of the polysiloxane A to obtain particles containing a polymer in which the polymer and the polysiloxane A are bonded by a siloxane bond;
Including,
The method for producing external additive particles is preferred.

A polymer in which the polymer obtained in step (i) and the polysiloxane A are bonded together is obtained by carrying out a hydrolysis reaction and a polycondensation reaction between the hydrolyzable group X of the polymer obtained in step (i) and the hydrolyzable group Y of the polysiloxane A. As a result, the polymer preferably has the polysiloxane moiety represented by L2 above. Furthermore, it is preferable that at least one silicon atom constituting the SiO _2/2 unit contained in the polysiloxane A is bonded to an alkyl group having 1 to 3 carbon atoms and a group represented by the following formula (3):
(R ³² )(R ³³ )(Si(R ³⁴ ) ₃ O )Si-R ³¹ -※※...(3)
(In the above formula (3), R ³² , R ³³ , and R ³⁴ are each independently an alkyl group having 1 to 3 carbon atoms, R ³¹ is an alkylene group having 1 to 3 carbon atoms, and ** is a bonding site to the silicon atom.)

In addition, with this manufacturing method, hydrolysis and polycondensation are carried out after the vinyl polymer molecular chains are formed, which is thought to make it easier to obtain external additive particles with a controlled ratio of silicon atoms, making it less likely that the amount of siloxane bonds will become excessive.

In formulas (4) to (6), R ⁵ to R ⁸ more preferably have 1 to 5 carbon atoms. R ⁹ in formula (7) is more preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms, and even more preferably a methyl group. R ¹⁰ in formula (7) is more preferably an alkylene group having 1 to 5 carbon atoms, and even more preferably an alkylene group having 1 to 3 carbon atoms.

Furthermore, R ¹¹ and R ¹² in formula (8) are more preferably alkyl groups having 1 to 5 carbon atoms, even more preferably alkyl groups having 1 to 3 carbon atoms, and even more preferably methyl groups.

The hydrolyzable group according to the present disclosure refers to a functional group that is converted into a hydroxy group when hydrolyzed while bonded to a silicon atom, or a hydroxy group. For example, 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 can be mentioned. Preferred alkoxy groups include a methoxy group, an ethoxy group, and a propoxy group, and preferred acyloxy groups include an acetoxy group. Preferred hydrolyzable groups according to the present disclosure are a hydroxy group, a methoxy group, an ethoxy group, a propoxy group, and an acetoxy group, and more preferred are a methoxy group and an ethoxy group.
The radically polymerizable group according to the present disclosure refers to a substituent having a radically reactive double bond in its structure, such as a vinyl group, an acryloxyalkyl group, or a methacryloxyalkyl group.

Furthermore, from the viewpoint of toner fluidity, the amount of at least one compound selected from the group consisting of compounds represented by formulas (4) to (6) is preferably 50 to 80% by mass, more preferably 60 to 75% by mass, based on the total mass of the monomer raw materials having a radical polymerizable group.

<Radical Polymerization Reaction (Step (i))>
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 also 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.

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% by mass, and more preferably 0.3 to 5.0% by mass, based on the total mass of the monomer raw materials having a radically polymerizable group. A radical polymerization initiator within the above range is preferred because it allows the radical polymerization to proceed sufficiently and prevents excessive heat generation in the reaction system.

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

The radical polymerization step (step (i)) is preferably carried out under conditions of 6.0≦pH≦8.0, and more preferably 6.5≦pH≦7.5. When the pH of the reaction system is within this range, it is believed that hydrolysis of hydrolyzable groups and polycondensation reactions are less likely to occur during the radical polymerization reaction. For this reason, the radical polymerization reaction is preferably carried out in a buffer solution. There are no particular restrictions on the buffer solution, and any buffer solution with a near-neutral pH, such as a phosphate buffer solution or an MES buffer solution, will do.

Furthermore, when performing radical polymerization, not only monomers containing both radically polymerizable groups and hydrolyzable groups may be used, but also other monomers having radically polymerizable groups.

Other monomers include, for example, 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 compounds such as halogenated vinyl compounds such as vinyl chloride. These 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.

<Hydrolysis reaction and polycondensation reaction (step (iii))>
In the production method according to the present disclosure, after the above-mentioned radical polymerization reaction, the above-mentioned polysiloxane A is added, and a hydrolysis reaction and a polycondensation reaction are carried out.

The methods for the hydrolysis reaction and polycondensation reaction are not particularly limited, but a preferred process involves adding a catalyst such as an acid or base to an emulsion containing particles obtained by radical polymerization, and then carrying out hydrolysis and polycondensation in that state to obtain polymer particles. Alternatively, the particles obtained by radical polymerization may be isolated from the emulsion by filtration, centrifugation, vacuum concentration, or other procedures, and then a catalyst may be added to carry out hydrolysis and polycondensation. Furthermore, step (iii) according to the present disclosure preferably includes a step of carrying out the reaction under conditions of 10.0≦pH≦12.0.

When carrying out hydrolysis or polycondensation reactions after particle formation by radical polymerization, catalysts such as acetic acid, hydrochloric acid, ammonia, urea, alkanolamine, tetraalkylammonium hydroxide, alkali metal hydroxide, and alkaline earth metal hydroxide may be used.

More preferred catalysts from the perspective of further accelerating polycondensation include organic titanium compounds such as titanium tetraisopropoxide, titanium tetrabutoxide, and diisopropoxy-bis(acetylacetonate)titanate; organic aluminum compounds such as aluminum triisopropoxide, aluminum trisec-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.

The solvent used in producing the external additive particles may also contain organic solvents other than water and catalysts. Specific examples of organic solvents 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 organic solvents may also be used in combination.

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.

<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 subjected to a drying treatment 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 likely to be obtained.

From the perspective of toner chargeability, it is preferable to treat the surface of the external additive particles obtained by the above production process with a surface treatment agent to treat any hydroxyl groups remaining on the surface and adjust the amount of negative charge. Examples of such surface treatment agents include silicon compounds such as organoalkoxysilane and hexamethyldisilazane, titanium compounds such as tetrabutyl titanate, and hydrolyzates and condensates of these.

The surface treatment method 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 external additive particles can be placed in a suitable container, followed by the surface treatment agent, and then the mixture is mixed and contacted with the external additive particles while stirring at room temperature (25°C ± 5°C) to approximately 100°C for 3 to 24 hours. In this case, a more uniform surface treatment can be achieved by dissolving the surface treatment agent in a solvent such as methanol and gradually adding this dropwise while mixing and contacting the particles. 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 other factors. 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.

<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.

The toner particles preferably contain a binder resin. Examples of such binder resins include polyester resins, vinyl resins, epoxy resins, and polyurethane resins.

From the standpoint of storage stability, it is preferable that the binder resin have a glass transition point (Tg) of 45 to 70°C.

<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.

The pulverization method will now be explained. In this method, the binder resin, colorant, wax, charge control agent, etc. that make up the toner particles are first thoroughly mixed using a mixer such as a Henschel mixer or ball mill. The resulting mixture is then melted and kneaded using a thermal mixer such as a twin-screw kneading extruder, heated roll, kneader, or extruder, and after cooling and solidifying, is pulverized and classified. This produces toner particles.

Examples of kneading machines include the following: KRC kneader (manufactured by Kurimoto Iron Works); Buss-Co kneader (manufactured by Buss); TEM 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.); Banbury mixer (manufactured by Kobe Steel, Ltd.).

Examples of pulverizers include: Counter Jet Mill, Micron Jet, Inomizer (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); 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.); Super Rotor (manufactured by Nisshin Engineering Co., Ltd.).

Classifiers include the following: Cruseal, Micron Classifier, and Spedic Classifier (manufactured by Seishin Enterprises); Turbo Classifier (manufactured by Nisshin Engineering); Micron Separator, Turboplex (ATP), and TSP Separator (manufactured by Hosokawa Micron Corporation); Elbow Jet (manufactured by Nittetsu Mining Co., Ltd.), Dispersion Separator (manufactured by Nippon Pneumatic Industry Co., Ltd.); and YM Microcut (manufactured by Yaskawa Shoji Co., Ltd.).

The suspension polymerization method is described below. In the suspension polymerization method, a polymerizable monomer capable of forming a binder resin and various additives, if necessary, are first mixed together to prepare a polymerizable monomer composition by dissolving or dispersing the materials using a disperser. Examples of 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 process). The polymerizable monomer in the droplets is then polymerized to obtain toner particles (polymerization process). The polymerization initiator may be added when preparing the polymerizable monomer composition, or it may be added to the polymerizable monomer composition immediately before forming droplets in the aqueous medium. Alternatively, the solvent may be added as a solution in a polymerizable monomer or another solvent during or after the granulation of the droplets, i.e., immediately before the polymerization reaction begins. After the polymerizable monomer is polymerized to obtain a binder resin, a solvent removal process may be carried out as necessary to obtain a dispersion of toner particles.

<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.

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).

Furthermore, it is preferable that the toner particles contain the above-mentioned external additive particles on their surfaces as well as other external additives. Examples of other external additives include the following:

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, and treated silica which has been surface-treated with a silane compound, 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.

<Various additives in 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.

<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.

Examples of magnetic particles contained in magnetic toner include:

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

The average particle size of the magnetic particles is preferably 2 μm or less, and more preferably 0.05 μm or more and 0.5 μm or less. Furthermore, the content of the magnetic particles is preferably 20 parts by weight or more and 200 parts by weight or less per 100 parts by weight of the binder resin, and more preferably 40 parts by weight or more and 150 parts by weight or less per 100 parts by weight of the binder resin.

<Coloring Agent>
Examples of colorants include the following:

Black colorants include, for example, carbon black, grafted carbon, and the yellow, magenta, and cyan colorants listed below, which are used to tone the color black.

Yellow colorants include compounds such as condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and allylamide compounds.

Magenta colorants include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds. Cyan colorants include copper phthalocyanine compounds and their derivatives, anthraquinone compounds, and basic dye lake compounds.

Colorants can be used alone or in mixtures, or even in the form of a solid solution. Furthermore, colorants are selected based on hue angle, saturation, brightness, weather resistance, transparency for overhead projectors, and dispersibility in toner.

The colorant content is preferably 1 part by weight or more and 20 parts by weight or less per 100 parts by weight of binder resin.

<Wax>
Examples of waxes include the following:

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

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

<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.

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 charge control agents described above.

<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.

Preferred magnetic carriers include, for example, surface-oxidized iron, non-oxidized iron, nickel, cobalt, manganese, chromium, rare earth metals, and alloys or oxides thereof.

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

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

<Method for measuring the ratio of the number of silicon atoms to the total number of carbon atoms, oxygen atoms, and silicon atoms present in external additive particles, and the abundance ratio of carbon atoms to silicon atoms>
Carbon atoms 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.
Device used: PerkinElmer 2400II fully automatic elemental analyzer, silicon atoms The concentration (atomic %) of silicon atoms present in the external additive particles is measured using elemental analysis by inductively coupled plasma atomic emission spectrometry (ICP-AES) using alkali fusion. The ICP-AES device is shown below.
Equipment used: Shimadzu ICPS-8100
The obtained composition ratio is converted into mole percent, 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.

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

To prevent aggregation of the measurement sample, a dispersion of the measurement sample is poured into an aqueous solution containing Family Fresh (manufactured by Kao Corporation) and stirred. After stirring, the measurement sample is poured into the above device and measured twice to determine the average value.

The measurement conditions are: measurement time 30 seconds, sample particle refractive index 1.49, dispersion medium water, dispersion medium refractive index 1.33.

Measure the volumetric particle size distribution of the measurement sample, and from the measurement results, the particle diameter at which the cumulative volume from the small particle diameter side in the cumulative volume distribution is 50% is taken as the 50% particle diameter (D50) based on the volume distribution of each microparticle.

The present disclosure will be explained in detail below using examples, but the present disclosure is not limited to these examples. Unless otherwise specified, "parts" and "%" mean "parts by mass" and "% by mass," respectively.

Example 1
<Production Example of External Additive 1>
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 (manufactured by Kishida Chemical Co., Ltd.) and disodium hydrogen phosphate dodecahydrate (manufactured by Kishida Chemical Co., Ltd.)) 200 parts Sodium p-styrenesulfonate (manufactured by Kishida Chemical Co., Ltd.) 0.13 parts Monomer having a radical polymerizable group and a hydrolyzable group: 3-(trimethoxysilyl)propyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) 11.0 parts Non-hydrolyzable monomer: styrene (manufactured by Tokyo Chemical Industry Co., Ltd.) 4.7 parts Subsequently, the mixture was heated to 65 to 70°C while aerating nitrogen gas and stirred for 30 minutes, after which 0.51 parts of potassium peroxodisulfate (manufactured by Kishida Chemical Co., Ltd.) was added as an initiator, and the mixture was stirred for 6 hours to carry out vinyl polymerization, thereby obtaining an emulsion of particles. To the obtained particle emulsion, 28% by mass ammonia water (manufactured by Kishida Chemical Co., Ltd.) was added as an ammonia treatment to adjust the pH of the emulsion to 11.0, and then 0.19 parts of KF-9908 (manufactured by Shin-Etsu Chemical Co., Ltd.) was added as polysiloxane (B). The mixture was then stirred at a temperature of 50°C for 24 hours to hydrolyze the hydrolyzable groups contained in the particles and polysiloxane B, and polycondensation was carried out. Ultrafiltration was then carried out to remove excess solute, and concentration/filtration was repeated a total of five times. The mixture was then dried by spray drying to obtain external additive 1 having a 50% particle size based on volume distribution (hereinafter referred to as D50) of 130 nm. The physical properties of external additive 1 are shown in Table 2.

<Production Example of Toner Particle 1>
The following materials were premixed in a Henschel mixer, and then melt-kneaded using a twin-screw extruder (trade name: PCM-30, manufactured by Ikegai Iron Works Co., Ltd.) at a 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 (C105 manufactured by Sasol Corporation, melting point: 105°C) 2 parts, charge control agent (T-77 manufactured by Hodogaya Chemical Co., Ltd.) 2 parts. The resulting kneaded product was cooled, coarsely pulverized using a hammer mill, and then finely pulverized using a pulverizer (product name: Turbo Mill T250, manufactured by Turbo Kogyo Co., Ltd.) to obtain a finely pulverized powder. The obtained finely pulverized powder was classified using a multi-division classifier utilizing the Coanda effect to obtain toner particles 1 having a weight average particle size of 7.2 μm.

<Production Example of Toner 1>
The external additive was added to toner particles 1 by a dry method. 100.0 parts of toner particles 1, 1.3 parts of external additive 1, and 1.5 parts of fumed silica (BET specific surface area: 200 ^m2 /g) were added to a Henschel mixer and externally mixed. The mixture was then sieved through a mesh with 150 μm openings to obtain toner 1 in which external additive 1 was externally added to toner particles 1.

<Evaluation>
Toner 1 was used to carry out the following evaluations.

<Evaluation of Toner Fluidity>
The fluidity of the toner was measured by the following method.

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, standard JIS Z8801-1) with mesh sizes 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 (%) shown in the following formula, where A represents the amount of toner remaining on the 150 μm mesh sieve, B represents the amount of toner remaining on the 100 μm mesh sieve, and C represents the amount of toner remaining on the 45 μm mesh sieve. The evaluation results are shown in Table 3. A fluidity index of 30% or less was determined to be one in which the effects of the present disclosure were achieved.

Fluidity index (%) = [(A + 0.6 × B + 0.2 × C) / measured sample mass] × 100
<Evaluation of Changes in Toner Charging Amount Due to Environmental Changes (Before Durability Test)>
First, two samples were prepared by placing 0.5 g of Toner 1 and 9.5 g of Carrier N-01 (manufactured by the Imaging Society of Japan) in a 50 mL polyethylene container. One sample was then left overnight in a room temperature, low humidity environment (20°C, 10% RH, hereinafter referred to as the NL environment), and the other sample was left overnight in a high temperature, high humidity environment (30°C, 80% RH, hereinafter referred to as the HH environment). Each sample was then shaken for 5 minutes at a shaking speed of 200 rpm, and the toner charge was measured using a Blow-Off Powder Charge Measurement System TB-200 (manufactured by Toshiba Chemical Corporation). The blow-off time was 2 minutes. The charge amount of the toner left in the HH environment was then subtracted from the charge amount of the toner left in the NL environment to determine the environmental difference in toner charge (μC/g).

<Evaluation of Changes in Toner Charging Amount Due to Environmental Changes (After Durability Test)>
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 (81.0 g/m ² ) (Canon Marketing Japan Inc.)
Toner amount on paper: 0.35 mg/cm ²
Process speed: 377 mm/sec. Thereafter, the residual toner in the cartridge was removed, and the residual toner was used to perform the same evaluation as in the evaluation of the environmental stability of toner charge described above. The measured value of the toner charge amount obtained in this evaluation was used as the toner charge amount after the durability test, and the environmental difference (μC/g) of the toner charge amount was calculated in the same manner as in the evaluation of the environmental stability of toner charge described above.

After the durability test, it was determined that the effects of the present disclosure were achieved when the environmental difference in toner charge amount was 30 μC/g or less.

The environmental difference in toner charge amount obtained from the above two evaluations was then substituted into the following formula to calculate the amount of variation.

Fluctuation amount (μC/g)=(environmental difference in toner charge amount after durability test (μC/g))−(environmental difference in toner charge amount before durability test (μC/g))
<Evaluation of Crushing of External Additive Particles and Detachment from Toner Particles>
Evaluation of crushing of external additive particles and detachment from toner particles was carried out after the durability test. After outputting 5,000 images, the toner 1 remaining 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 that crushing had occurred, and if recesses from which external additive particles had detached were observed on the surface of the toner, it was judged that detachment had occurred.

<Examples 2 to 9, 11 and Comparative Examples 1 to 3>
External additives 2 to 9 and 11 to 14 were obtained by the same procedure as in Example 1, except that the materials used were changed as shown in Table 1, and then similar evaluations were carried out. The physical properties of external additives 2 to 9 and 11 to 14 are shown in Table 2. The evaluation results are shown in Table 3. Comparative Example 1 is a comparative example in which the structure shown in (1) above is not contained in the polymer having a vinyl polymer moiety. This is because the polysiloxane (B) added in Comparative Example 1 does not have a reactive site capable of bonding with the polymer.

<Comparative Example 4>
The same procedure as in Example 1 was carried out to obtain External Additive 15, except that External Additive 1 was changed to the following External Additive 15. Then, a toner was produced in the same manner as in Example 1, and evaluated. The evaluation results are shown in Table 3.

[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 of deionized water, 0.13 parts of ionic monomer: sodium p-styrenesulfonate, 6.3 parts of non-hydrolyzable monomer: butyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), and 4.7 parts of styrene. Subsequently, the mixture was heated to 65-70°C while aerating nitrogen gas, 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 a particle emulsion. Thereafter, 28% by mass aqueous ammonia (manufactured by Kishida Chemical Co., Ltd.) was added to adjust the pH of the emulsion to 11.0, and then 0.19 parts of KF-9908 (manufactured by Shin-Etsu Chemical Co., Ltd.) was added as polysiloxane (B). Then, the mixture was stirred at a temperature of 50°C for 24 hours to hydrolyze the hydrolyzable groups contained in polysiloxane B and polycondensate. Thereafter, ultrafiltration was performed to remove excess solute, and concentration/filtration was repeated a total of 5 times. After that, it was dried by spray drying to obtain external additive 15. The physical properties of the external additive 15 are shown in Table 2.

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 MA-CDMSP: 3-(chlorodimethylsilyl)propyl methacrylate MAB: butyl methacrylate St: styrene NaPSS: sodium p-styrenesulfonate KPS: potassium peroxodisulfate KF-9908 (trade name): triethoxysilylethyl polydimethylsiloxyethyl dimethicone (manufactured by Shin-Etsu Chemical Co., Ltd.)
KF-9909 (trade name): Triethoxysilylethyl polydimethylsiloxyethylhexyl dimethicone (manufactured by Shin-Etsu Chemical Co., Ltd.)
KF-96-50cs (product name): dimethyl silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd.)
KF-9908 and KF-9909 used in the examples are polysiloxanes having SiO _2/2 units represented by the following formula (10), SiO _2/2 units represented by the following formula (11), and SiO _2/2 units represented by the following formula (12). KF-9909 is a polysiloxane further having SiO _2/2 units represented by the following formula (13).

The values in Table 2 were measured using the measurement method described above. Also, in Table 2, 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 particles.

Claims (8)

An external additive particle comprising a polymer having a vinyl polymer portion and a polysiloxane 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 polymer has a structure represented by the following formula (1) :

(In formula (1),
R' is a hydrogen atom or a methyl group;
L2 is a polysiloxane moiety containing SiO _3/2 units and SiO _2/2 units, and at least one silicon atom constituting the SiO _2/2 units has two alkyl groups having 1 to 10 carbon atoms bonded to the silicon atom, and at least one silicon atom constituting the SiO _3/2 units has a group represented by the following formula (2):
R ³ -SiO _2/2 -R ⁴ -*...(2)
(In the above formula (2), R3 ^is an alkyl group having 1 to 6 carbon atoms, R4 ^is an alkylene group having 1 to 10 carbon atoms, and * indicates the bonding site with the silicon atom.)
A group represented by
L1 is *-COOR ¹ -** or *-COOR ¹ -SiR ² ₂ -O-**, R ¹ is an alkylene group having 1 to 10 carbon atoms, each R ² is independently an alkyl group having 1 to 10 carbon atoms, * is the bonding site to the carbon atom bonded to R ^′ in formula (1), and ** is the bonding site to the silicon atom constituting the SiO _3/2 unit contained in L2 . 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 external additive particles according to claim 1 . When the 50% particle diameter of the external additive particles based on the volume distribution is defined as D50,
3. The external additive particles according to claim 1, wherein the D50 is 50 nm or more and 200 nm or less. The external additive particles according to any one of claims 1 to 3, wherein an alkyl group having 1 to 3 carbon atoms and a group represented by the following formula (3) are bonded to at least one silicon atom constituting the SiO _2/2 unit :
(R ³² )(R ³³ )(Si(R ³⁴ ) ₃ O )Si-R ³¹ -※※...(3)
(In the above formula (3), R ³² , R ³³ , and R ³⁴ are each independently an alkyl group having 1 to 3 carbon atoms, R ³¹ is an alkylene group having 1 to 3 carbon atoms, and ** is a bonding site to the silicon atom. ) 5. The external additive particle according to claim 1 , wherein the polymer is a polymer in which a vinyl polymer is crosslinked by a siloxane bond. A toner containing toner particles and an external additive on the surfaces of the toner particles,
A toner, wherein the external additive is the external additive particles according to any one of claims 1 to 5 . A method for producing external additive particles containing a polymer, comprising:
The manufacturing method comprises:
(i) performing a radical polymerization reaction of a monomer raw material containing at least one compound selected from the group consisting of a compound represented by the following formula (4) and a compound represented by the following formula (6) to obtain a polymer having a hydrolyzable group X;

(In formulas (4) and (6), X ¹ to X ³ and X ⁷ each independently represent a hydrolyzable group X, and R' each independently represent a hydrogen atom or a methyl group. R ⁵ and R ⁶ each independently represent an alkylene group having 1 to 10 carbon atoms, and R ⁷ and R ⁸ each independently represent an alkyl group having 1 to 10 carbon atoms.)
(ii) adding the following polysiloxane A having a hydrolyzable group Y (Polysiloxane A: a polysiloxane containing SiO _2/2 units, the SiO _2/2 units being at least SiO _2/2 units represented by the following formula (7) and SiO _2/2 units represented by the following formula (8)

(In formula (7), R ⁹ is an alkyl group having 1 to 10 carbon atoms, R ¹⁰ is an alkylene group having 1 to 10 carbon atoms, and Y is a hydrolyzable group. In formula (8), R ¹¹ and R ¹² are each independently an alkyl group having 1 to 10 carbon atoms.)
(iii) performing a hydrolysis reaction and a polycondensation reaction between the hydrolyzable group X of the polymer and the hydrolyzable group Y of the polysiloxane A to obtain particles containing a polymer in which the polymer and the polysiloxane A are bonded by a siloxane bond;
Including,
Method for producing external additive particles. The method for producing external additive particles according to claim 7, wherein the hydrolyzable group X and the hydrolyzable group Y are each independently at least one selected from the group consisting of a hydroxy group, a methoxy group, an ethoxy group , a propoxy group, and an acetoxy group.