JP2012003176A - Electrostatic charge image developing toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner scattering less toner into an unit-inside, preventing image fogging, and stably providing a high-density printed image even by printing continuously by being loaded into a high speed image-forming device(e.g. 65 sheet/min, A4-sized, cross feed).SOLUTION: An electrostatic charge image developing toner including at least a binder resin and colorant. A hydrophobicity degree of the electrostatic charge image developing toner is 30% or less.

Description

  The present invention relates to a toner for developing an electrostatic image.

  At present, in the electrophotographic system, as the printing speed increases, there is a demand for good charge rising of toner.

  As an electrostatic charge image developing toner having good chargeability, an electrostatic charge developing toner containing at least a binder resin and a release agent, a metal element capable of taking a valence of 2 or more, and a sulfone A technique for containing a surfactant having a group and a surfactant having a carboxyl group is disclosed (for example, see Patent Document 1).

  However, when the toner obtained as described above is loaded into a high-speed image forming apparatus and printing is performed, the rise of charging is slow, and there is a problem that fogging occurs in the printed image.

  In addition, by uniformly adhering and adding external additives to the surface of the colored resin particles (external addition), the charging start-up property is good, initial fogging hardly occurs, and the initial printability is excellent and stable over time. Thus, there has been disclosed a technology for developing an electrostatic charge image that imparts the electrification property to toner particles, hardly deteriorates in image quality due to fog or the like even when continuous printing of a large number of sheets is performed, and is excellent in durable printability ( For example, see Patent Documents 2 and 3.)

JP 2008-76519 A JP 2009-237338 A JP 2009-229612 A

  However, even if the toner produced using the technology disclosed above is loaded in a high-speed image forming apparatus (for example, 65 sheets / minute A4 size lateral feed) and solid images are printed continuously, the charge rises. However, the toner for developing an electrostatic charge image (hereinafter, also simply referred to as toner) is scattered in the apparatus, image fogging occurs, and the image density is lowered.

  In addition, the toner produced by using the technique disclosed above has a problem in the durability of the effect because the additive is peeled off from the toner particle surface by agitation in the developing device during printing of a large number of sheets.

  An object of the present invention is to stably obtain a high-density printed image even if it is loaded in a high-speed image forming apparatus (for example, 65 sheets / 1 minute A4 size lateral feed) and continuously printed, and print a large number of sheets. Another object of the present invention is to provide a toner that does not cause image fogging and causes less toner scattering in the apparatus.

  The object of the present invention is achieved by the following configurations.

  1. An electrostatic charge image developing toner, comprising at least a binder resin and a colorant, wherein the electrostatic charge image developing toner has a hydrophobicity of 30% or less.

  2. 2. The electrostatic image developing toner according to 1 above, wherein the amount of the surfactant contained in the electrostatic image developing toner is 0.1% by mass or more and 1.0% by mass or less.

  3. 3. The electrostatic image developing toner according to 1 or 2 above, wherein the toner is produced through a process of aggregating and fusing at least resin particles and a colorant in an aqueous medium.

  The toner of the present invention can stably obtain a high-density printed image even if it is loaded in a high-speed image forming apparatus (for example, 65 sheets / 1 minute A4 size lateral feed) and continuously printed. However, image fogging does not occur, toner scattering into the machine is small, and an excellent effect is obtained.

1 is a schematic cross-sectional view of an image forming apparatus in which the toner of the present invention is preferably used.

  The inventors of the present invention can stably obtain a high-density print image even if it is loaded in a high-speed image forming apparatus (for example, 65 sheets / 1 minute A4 size lateral feed) and continuously printed, and print a large number of sheets. Also, a toner that does not cause image fogging and causes less toner scattering in the machine was examined.

  As a result of various studies, it has been found that the above object can be satisfied by printing with toner having a low degree of hydrophobicity (for example, a degree of hydrophobicity of 30% or less).

  In order to reduce the hydrophobicity of the toner, the surface of the toner particles contains a large amount of hydrophilic functional groups (including salts thereof) such as carboxyl groups and sulfo groups and hydrophilic inorganic salts (for example, NaCl). Can be obtained.

  It is considered that these hydrophilic functional groups and inorganic salts improve the charge rise.

  In addition, since the toner having a low degree of hydrophobicity has good wettability with water, the surfactant attached to the toner particles can be sufficiently removed by washing with water. It is considered that the charge rise is further improved by setting the surfactant remaining in the toner to 1.0% by mass or less.

  The smaller the remaining amount of the surfactant, the better. However, the amount of the surfactant is preferably set to 0.1% by mass in consideration of the toner productivity.

Toner with a hydrophobicity of 30% or less
1. 1. Increasing the amount of carboxylic acid-containing polymerizable monomer during preparation of the toner. Free the carboxylic acid by alkali cleaning (orient the surface more)
3. It can be obtained by adding a specific salt during the preparation of the toner or after the preparation so that the salt is present on the surface of the toner particles.

  For example, it can be obtained by adding a salt such as sodium chloride or tetrabutylammonium fluoride dihydrate to the toner particle surface during or after the toner preparation. The presence on the surface of the toner particles can be confirmed by, for example, ESCA.

  Hereinafter, the present invention will be described in detail.

<< Hydrophobicity >>
In the present invention, the degree of hydrophobicity of toner is defined as the time when methanol (ml) is added while stirring a solution of toner (g) in pure water (ml) and the toner starts to settle ( The amount of methanol added at the descent start point) was calculated and calculated from the following formula.

Hydrophobic degree = methanol added amount / total solution amount (pure water + methanol added amount) × 100 (%)
(Measurement of hydrophobicity)
The starting point of descent in the degree of hydrophobicity (methanol wettability) of the toner can be measured using a powder wettability tester (WET-100P, manufactured by Reska Co.). To an aqueous solution in which 50 ml of pure water (ion-exchanged water or commercially available purified water) at 24 ° C. is put in a 100 ml beaker, 0.5 g of toner left in 23 ° C. and 50% RH for 12 hours is precisely weighed and added. While stirring the stirrer at 250 rpm, methanol is added at a rate of 1.3 ml / min. When the toner starts to settle in the aqueous solution, the addition of methanol is stopped, and the degree of hydrophobicity is obtained from the above formula.

《Surfactant remaining amount》
In the present invention, the remaining amount of surfactant refers to the amount of surfactant contained in the toner.

(Measurement of remaining amount of surfactant)
After 1.0 g of toner is immersed in 100 ml of chloroform, water 50 ml × separated and extracted twice. After lyophilization of the aqueous phase, 1HNMR ( ¹ H-NMR spectrum) and LC / MS (liquid chromatograph mass spectrometer LC-MS) were performed on the solid content, the structure of the surfactant was examined, and HPLC (high performance liquid chromatograph) ).

  In addition, the method of adjusting surfactant residual amount with a washing | cleaning condition is preferable.

(HPLC conditions)
Column: Acclaim Surfactant 4.6 * 150 mm (Dionex) 40 ° C.
Eluent: 0.1M ammonium acetate (pH 5.0) / acetonitrile = 6/4
Flow rate: 1.0 ml / min
Detection: Corona CAD
"toner"
The toner of the present invention has at least a binder resin and a colorant.

  The toner of the present invention has a hydrophobicity of 30% or less, preferably 20% or less.

  In the present invention, the toner is an aggregate of toner particles.

<Method for producing toner>
Toner with a hydrophobicity of 30% or less
1. 1. Increase the proportion of carboxylic acid-containing monomer (for example, methacrylic acid) in the polymerizable monomer (monomer) in the dispersion preparation step. In the solid-liquid separation / washing process, the carboxylic acid is freed by alkali washing (orientated on the surface more).
3. The toner can be produced by at least one of adding a specific salt to make the toner surface exist during or after the toner preparation.

  In addition, as a method of “freeing the carboxylic acid by alkali cleaning”, in the following toner production method step (4) “solid-liquid separation / washing step”, washing with a washing solution having a pH of 10 or higher, or re-slurry solution with a pH of 10 The method of making it above can be mentioned.

  As a method of “adding a specific salt to be present on the toner surface”, after reaching the target particle size in the following step (3) of “preparing a dispersion of toner base particles” of the toner production method, It is added before the cooling treatment in step (4). Alternatively, in the step (4) solid-liquid separation / washing step, a method of adding a specific salt to the reslurry liquid can be mentioned.

The toner is preferably produced through a process of aggregating and fusing at least resin particles and a colorant in an aqueous medium. For example, the toner can be produced through the following processes.
(1) Dispersion preparation step for dissolving or dispersing a release agent in a polymerizable monomer (2) Step of producing a resin particle that becomes a binder resin by polymerizing the polymerizable monomer (3) In an aqueous medium A step of agglomerating and fusing the resin particles and the colorant in the presence of polyvalent metal ions to prepare a dispersion of toner base particles (4) separating the toner base particles from the toner base particle dispersion; Solid-liquid separation / washing step for removing surfactant from the toner base particles (5) Drying step for drying the washed toner base particles (6) Adding external additives to the dried toner base particles Attachment process Each process will be described below.
(1) Dispersion preparation step This step is a step of preparing a solution in which a release agent is dissolved or dispersed in a polymerizable monomer.
(2) Step of producing resin particles In a preferred example of this step, the above liquid is added to an aqueous medium containing a surfactant, mechanical energy is added to form droplets, and then water-soluble The radical polymerization initiator is added to cause the polymerization reaction to proceed in the droplets to form a resin. An oil-soluble polymerization initiator may be contained in the droplet. In such a polymerization process, mechanical energy is imparted and forcedly emulsified (formation of droplets) is essential. Examples of the mechanical energy applying means include strong stirring such as homomixer, ultrasonic wave, and manton gorin or ultrasonic vibration energy applying means.

By this step, resin particles containing a release agent and a resin are obtained.
(3) Step of preparing toner base particles The toner base particles can be prepared by aggregating and fusing resin particles and a colorant in the presence of a polyvalent metal ion in an aqueous medium. Further, in the step of producing toner base particles, fine particles of internal additives such as release agent particles and charge control agents can be aggregated and fused together with resin particles and colorants. For example, the pH in an aqueous medium in which resin particles and a colorant are present is adjusted, an aggregating agent made of a polyvalent metal ion compound is added, and then heated to a temperature equal to or higher than the glass transition point of the resin particles. As a result, the agglomeration can be advanced and fusion can be performed at the same time.

  “Aqueous medium” refers to a main component (50% by mass or more) composed of water. Examples of components other than water include organic solvents that dissolve in water, such as methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, and tetrahydrofuran.

  As the colorant, a colorant dispersion liquid dispersed in an aqueous medium is used. The dispersion treatment of the colorant is performed in a state where the surfactant concentration is set to a critical micelle concentration (CMC) or more in water. The disperser used for the dispersion treatment of the colorant is not particularly limited, but preferably an ultrasonic disperser, a mechanical homogenizer, a pressure disperser such as a manton gorin or a pressure homogenizer, a sand grinder, a Getzmann mill, a diamond fine mill, or the like. Examples thereof include a medium type disperser.

Through this step, a dispersion of toner base particles is obtained.
(4) Solid-liquid separation / washing step First, the dispersion of the toner base particles is cooled. As a cooling treatment condition, cooling is performed at a cooling rate of 1 to 20 ° C./min. The cooling method is not particularly limited.

In the solid-liquid separation / washing step, the solid-liquid separation process for solid-liquid separation of the toner base particles from the dispersion of the toner base particles cooled to a predetermined temperature in the above-described step, and the solid-liquid separated toner cake (wet state) And a cleaning process for removing deposits such as a surfactant and an aggregating agent from the aggregate of toner base particles in the form of a cake). Here, the filtration method is not particularly limited, such as a centrifugal separation method, a vacuum filtration method using Nutsche or the like, a filtration method using a filter press or the like.
(5) Drying step This step is a step of drying the washed cake to obtain dried toner base particles. Examples of dryers used in this process include spray dryers, vacuum freeze dryers, vacuum dryers, etc., stationary shelf dryers, mobile shelf dryers, fluidized bed dryers, rotary dryers It is preferable to use a stirring dryer or the like. The moisture content of the dried toner base particles is preferably 1.0% by mass or less, and more preferably 0.5% by mass or less. When the toner base particles that have been dried are aggregated with weak interparticle attractive forces, the aggregate may be crushed. Here, as the crushing treatment apparatus, a mechanical crushing apparatus such as a jet mill, a Henschel mixer, a coffee mill, or a food processor can be used.
(6) External Addition Step This step is a step for preparing a toner by mixing an external additive with the dried toner base particles.

  As an external additive mixing device, a mechanical mixing device such as a Henschel mixer or a coffee mill can be used.

  Next, members used for producing the toner of the present invention will be described.

(Resin that forms resin particles)
The resin particles are not particularly limited and can be prepared by polymerizing a known polymerizable monomer. Preferably, it is prepared by copolymerizing at least a polymerizable monomer having a carboxyl group and another polymerizable monomer.

  Examples of the polymerizable monomer having a carboxyl group include acrylic acid, methacrylic acid, maleic acid, fumaric acid, and itaconic acid. In addition, examples of other polymerizable monomers include polymerizable monomers such as styrene, propyl acrylate, propyl methacrylate, butyl acrylate, and 2-ethylhexyl acrylate.

(Coloring agent)
As the colorant, carbon black, black iron oxide, dye, pigment and the like can be arbitrarily used. As the carbon black, channel black, furnace black, acetylene black, thermal black, lamp black and the like are used. As black iron oxide, magnetite, hematite, iron iron trioxide, or the like can be used.

  As the dye, C.I. I. Solvent Red 1, 49, 52, 58, 63, 111, 122, C.I. I. Solvent Yellow 19, 44, 77, 79, 81, 82, 93, 98, 103, 104, 112, 162, C.I. I. Solvent Blue 25, 36, 60, 70, 93, 95, etc. can be used, and mixtures thereof can also be used. Examples of the pigment include C.I. I. Pigment Red 5, 48: 1, 48: 3, 53: 1, 57: 1, 81: 4, 122, 139, 144, 149, 150, 166, 177, 178, 222, 238, C.I. I. Pigment Orange 31 and 43, C.I. I. Pigment yellow 14, 17, 74, 93, 94, 138, 155, 156, 158, 180, 185, C.I. I. Pigment green 7, C.I. I. Pigment Blue 15: 3, 60, etc. can be used, and a mixture thereof can also be used. The number average primary particle size varies depending on the type, but is preferably about 10 to 200 nm.

(Release agent)
A conventionally well-known thing can be used as a mold release agent. Preferably, polyolefin waxes such as polyethylene wax and polypropylene wax, long-chain hydrocarbon waxes such as paraffin wax and sazol wax, dialkyl ketone waxes such as distearyl ketone, carnauba wax, montan wax, trimethylolpropane tribe. Henate, pentaerythritol tetramyristate, pentaerythritol tetrastearate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1,18-octadecanediol distearate, behenyl behenate, Ester waxes such as tristearyl trimellitic acid and distearyl maleate, ethylenediamine dibehenyl amide, tris trimellitic acid Such as amide-based waxes such as allyl amide and the like.

  Melting | fusing point of a mold release agent is 40-160 degreeC normally, Preferably it is 50-120 degreeC, More preferably, it is 60-90 degreeC. By setting the melting point within the above range, the heat-resistant storage stability of the toner is ensured, and stable toner image formation can be performed without causing cold offset or the like even when fixing at a low temperature. Further, the content of the release agent in the toner is preferably 1% by mass to 30% by mass, and more preferably 5% by mass to 20% by mass.

(Charge control agent)
The toner can contain a charge control agent as required. A known compound can be used as the charge control agent.

(External additive)
The toner base particles can be used as a toner as they are, but it is preferable to add an external additive in order to improve fluidity, chargeability, cleaning properties and the like.

  Examples of the external additive include inorganic oxide fine particles such as silica fine particles, alumina fine particles, and titanium oxide fine particles, inorganic stearic acid compound fine particles such as calcium stearate fine particles and zinc stearate fine particles, or calcium titanate and titanic acid. Examples include inorganic titanic acid compound fine particles such as zinc. The number average primary particle diameter of these inorganic fine particles is preferably in the range of 10 to 1000 nm, more preferably in the range of 10 to 300 nm. These can be used alone or in combination of two or more.

  Further, as the external additive, spherical organic fine particles having a number average primary particle diameter of about 10 to 2000 nm can be used. As such organic fine particles, polymers such as polystyrene, polymethyl methacrylate, and styrene-methyl methacrylate copolymer can be used.

  The total amount of these various external additives added is 0.05 to 5 parts by mass, preferably 0.1 to 3 parts by mass with respect to 100 parts by mass of the toner. Further, various external additives may be used in combination.

<Developer>
The toner of the present invention can be used as a magnetic or nonmagnetic one-component developer, but may be mixed with a carrier and used as a two-component developer. When the toner of the present invention is used as a one-component developer, a non-magnetic one-component developer or a magnetic one-component developer containing about 0.1 to 0.5 μm of magnetic particles in the toner can be mentioned. Any of them can be used. In the case where the toner of the present invention is used as a two-component developer, the carrier may be a conventionally known material such as a metal such as iron, ferrite, or magnetite, or an alloy of such a metal with a metal such as aluminum or lead. In particular, ferrite particles are preferable. As the carrier, a coated carrier in which the surface of magnetic particles is coated with a coating agent such as a resin, a resin dispersion type carrier in which magnetic fine powder is dispersed in a binder resin, or the like may be used.

  The coating resin constituting the coat carrier is not particularly limited, and examples thereof include olefin resins, styrene resins, styrene-acrylic resins, acrylic resins, silicone resins, ester resins, and fluorine-containing polymer resins. . Moreover, it does not specifically limit as resin which comprises a resin dispersion type carrier, A well-known thing can be used, For example, a styrene-acrylic-type resin, a polyester resin, a fluororesin, a phenol resin etc. can be used.

  As a preferable carrier, a coated carrier coated with a styrene-acrylic resin-based resin or an acrylic resin can be used as a coating resin from the viewpoint of preventing the external additive from being detached and durability.

The carrier preferably has a median diameter (D ₅₀ ) of 20 to 100 μm, more preferably 25 to 80 μm, based on the volume. The median diameter (D ₅₀ ) based on the volume of the carrier can be measured by a laser diffraction particle size distribution measuring apparatus “HELOS” (manufactured by SYMPATEC) equipped with a wet disperser.

<Image forming apparatus>
The toner of the present invention can be used by being loaded into a high-speed (for example, 65 sheets / 1 minute A4 size lateral feed) monochrome image forming apparatus or a high-speed color image forming apparatus.

  An image forming apparatus in which the toner of the present invention is preferably used will be described.

  The image forming apparatus preferably used in the present invention comprises at least a charging means for charging the surface of the photoreceptor, an exposure means for exposing the charged photoreceptor to form an electrostatic latent image, and an electrostatic latent image on the photoreceptor. Development means for developing with toner to form a toner image, primary transfer means for transferring the toner image on the photoreceptor onto the intermediate transfer body, and secondary for transferring the toner image transferred onto the intermediate transfer body onto the transfer material Transfer means and means for heat-fixing the toner image transferred onto the transfer material onto the transfer material using a fixing device comprising a heating roller and a pressure roller (a belt is also used).

  In addition to the above-described units, the image forming apparatus preferably includes a cleaning unit for cleaning the intermediate transfer member and a unit for applying a lubricant to the surface of the photoreceptor.

  FIG. 1 is a schematic sectional view of an image forming apparatus in which the toner of the present invention is preferably used.

  This image forming apparatus is called a tandem color image forming apparatus, and includes a plurality of sets of image forming units 10Y, 10M, 10C, and 10K, an endless belt-shaped intermediate transfer body unit 7 as a transfer unit, and a transfer material P. And a fixing device 24 composed of a heating roller and a pressure roller as fixing means (fixing device). A document image reading device SC is disposed on the upper part of the main body A of the image forming apparatus.

  As one of the different color toner images formed on each photoconductor, an image forming unit 10Y that forms a yellow image includes a drum-shaped photoconductor 1Y as a first image carrier, and the photoconductor 1Y. A charging unit 2Y, an exposure unit 3Y, a developing unit (developing device) 4Y, a primary transfer roller 5Y as a primary transfer unit, and a cleaning unit 6Y are arranged around the periphery. An image forming unit 10M that forms a magenta image as another different color toner image is arranged around a drum-shaped photoconductor 1M as a first image carrier, and around the photoconductor 1M. The charging unit 2M, the exposure unit 3M, the developing unit 4M, the primary transfer roller 5M as the primary transfer unit, and the cleaning unit 6M are included. In addition, an image forming unit 10C that forms a cyan image as another different color toner image includes a drum-shaped photoreceptor 1C serving as a first image carrier, and the periphery of the photoreceptor 1C. A charging unit 2C, an exposure unit 3C, a developing unit 4C, a primary transfer roller 5C as a primary transfer unit, and a cleaning unit 6C are disposed. An image forming unit 10K that forms a black image as one of other different color toner images is disposed around a drum-shaped photoreceptor 1K as a first image carrier, and the periphery of the photoreceptor 1K. A charging unit 2K, an exposure unit 3K, a developing unit 4K, a primary transfer roller 5K as a primary transfer unit, and a cleaning unit 6K.

  The endless belt-like intermediate transfer body unit 7 includes an endless belt-like intermediate transfer body 70 as a second image carrier having a semiconductive endless belt shape that is wound around a plurality of rollers and is rotatably supported.

  Each color image formed by the image forming units 10Y, 10M, 10C, and 10K is sequentially transferred and synthesized on the rotating endless belt-shaped intermediate transfer body 70 by the primary transfer rollers 5Y, 5M, 5C, and 5K. A color image is formed. The transfer material P accommodated in the paper feeding cassette 20 is fed by the paper feeding / conveying means 21 and passes through a plurality of intermediate rollers 22A, 22B, 22C, 22D, and a registration roller 23, and is used as a secondary transfer means. The color image is transferred onto the transfer material P by being conveyed to the transfer roller 5A. The transfer material P onto which the color image has been transferred is fixed by a fixing device 24 composed of a heating roller and a pressure belt, and is sandwiched between discharge rollers 25 and placed on a discharge tray 26 outside the apparatus. The

  On the other hand, after the color image is transferred to the transfer material P by the secondary transfer roller 5A, the residual toner is removed from the endless belt-shaped intermediate transfer body 70 from which the transfer material P is separated by the curvature by the cleaning means 6A.

  In this way, toner images are formed on the photoreceptors 1Y, 1M, 1C, and 1K by charging, exposure, and development, and the toner images of the respective colors are superimposed on the endless belt-shaped intermediate transfer body 70, and are collectively applied to the transfer material P. The image is transferred and fixed by pressing and heating by a fixing device 24 composed of a heating roller and a pressure roller. After the toner image is transferred to the endless belt-shaped intermediate transfer body 70, the photoreceptors 1Y, 1M, 1C, and 1K use the cleaning means 6Y, 6M, 6C, and 6K to clean the toner remaining on the photoreceptor during transfer. Then, the charging, exposure and development cycles described above are entered, and the next image formation is performed.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, the aspect of this invention is not limited to this.

<Production of toner>
The toner was prepared as follows.

<Preparation of colorant dispersion>
90 parts by mass of sodium dodecyl sulfate was dissolved in 1590 parts by mass of ion-exchanged water with stirring. While stirring this solution, 420 parts by mass of carbon black “Regal 330R” (Cabot Corp.) is gradually added, and then dispersed using a stirring device “Cleamix” (M Technique Corp.). A colorant dispersion was prepared. The volume average particle size of this dispersion was measured using “Microtrac UPA150” (manufactured by Nikkiso Co., Ltd.) and found to be 117 nm.

<Preparation of Resin Particle A>
(First stage polymerization)
Into a reaction vessel equipped with a stirrer, temperature sensor, condenser, and nitrogen introduction device, 8 parts by weight of sodium dodecyl sulfate and 3000 parts by weight of ion-exchanged water were charged, and the internal temperature was kept while stirring at a stirring speed of 230 rpm under a nitrogen stream. The temperature was raised to 80 ° C. After the temperature increase, 10 parts by mass of potassium persulfate dissolved in 200 parts by mass of ion-exchanged water was added, the liquid temperature was again adjusted to 80 ° C., and the following monomer mixture was added dropwise over 1 hour, and then to 80 ° C. Then, polymerization was carried out by heating and stirring for 2 hours to prepare resin particles. This is referred to as “resin particles (1H)”.

Styrene 480 parts by weight n-butyl acrylate 250 parts by weight Methacrylic acid 68.0 parts by weight n-octyl mercaptan 16.0 parts by weight (second stage polymerization)
The following monomer mixture was heated to 90 ° C. with stirring, and 190 parts by mass of ester wax (melting point 70 ° C.) was dissolved in this mixture to prepare a “wax-containing monomer mixture”.

Styrene 245 parts by mass n-butyl acrylate 120 parts by mass n-octyl mercaptan 1.5 parts by mass A polyoxyethylene (2) sodium dodecyl ether sulfate 7 in a reaction vessel equipped with a stirrer, temperature sensor, condenser, and nitrogen introducing device 7 A solution in which 800 parts by mass of ion-exchanged water is dissolved is charged, and after heating to 98 ° C., 260 parts by mass of the resin particles (1H) and the wax-containing monomer mixture are added, and a circulation path is established. A dispersion liquid containing emulsified particles (oil droplets) was prepared by mixing and dispersing for 1 hour using a mechanical disperser CLEARMIX (manufactured by M Technique Co., Ltd.).

  Next, an initiator solution in which 6 parts by mass of potassium persulfate is dissolved in 200 parts by mass of ion-exchanged water is added to this dispersion, and polymerization is performed by heating and stirring the system at 82 ° C. for 1 hour. Resin particles were obtained. This is referred to as “resin particles (1HM)”.

(Third stage polymerization)
Furthermore, a solution prepared by dissolving 11 parts by mass of potassium persulfate in 400 parts by mass of ion-exchanged water was added, and under a temperature condition of 82 ° C.,
Styrene 435 parts by weight n-butyl acrylate 130 parts by weight Methacrylic acid 33 parts by weight n-octyl mercaptan 8 parts by weight of a monomer mixture was added dropwise over 1 hour. After completion of the dropping, polymerization was carried out by heating and stirring for 2 hours, and then cooled to 28 ° C. to obtain resin particles. This is designated as “resin particle A”.

<Preparation of resin particles B and C>
“Resin particles B” and “resin particles C” were prepared in the same manner except that the polymerizable monomer used in the production of the resin particles A was changed as shown in Table 1.

<Preparation of Toner 1>
(Process for preparing a dispersion of toner base particles)
In a reaction vessel equipped with a stirrer, a temperature sensor, and a cooling tube, 300 parts by mass of resin particles A, 1400 parts by mass of ion-exchanged water, 120 parts by mass of a colorant dispersion, and polyoxyethylene (2 ) A solution prepared by dissolving 3 parts by mass of sodium dodecyl ether sulfate in 120 parts by mass of ion-exchanged water was added and the liquid temperature was adjusted to 30 ° C. Then, a 5N aqueous sodium hydroxide solution was added to adjust the pH to 10. Next, an aqueous solution in which 35 parts by mass of magnesium chloride was dissolved in 35 parts by mass of ion-exchanged water was added at 30 ° C. over 10 minutes with stirring. After holding for 3 minutes, the temperature was raised and the system was heated to 90 ° C. over 60 minutes, and the particle growth reaction was continued while maintaining 90 ° C. In this state, the particle size of the associated particles was measured by “Coulter Multisizer 3 (manufactured by Beckman Coulter)”, and when the median diameter (D ₅₀ ) on the volume basis became 6.5 μm, 30 mass of sodium chloride was obtained. An aqueous solution in which a part is dissolved in 120 parts by mass of ion-exchanged water is added to stop particle growth.Further, as a ripening step, the fusion between the particles proceeds by heating and stirring at a liquid temperature of 90 ° C. for 1 hour, A “dispersion of toner base particles 1” was prepared.

(Solid-liquid separation and washing process)
The toner base particles were solid-liquid separated with a Nutsche from the dispersion of the toner base particles 1 produced in the above step, and the toner base particles were recovered as a wet cake.

  The recovered wet cake was re-slurried by stirring for 5 minutes at a rotation speed of 170 rpm in 40 ° C. ion-exchanged water of 10 mass times the solid content (toner base particles).

  1 M (mol / L) hydrochloric acid was added dropwise to the reslurry liquid to adjust the pH to 4.0, and then an aqueous solution in which 3 parts by mass of sodium chloride was dissolved in 12 parts by mass of ion-exchanged water was added, and stirring was continued for 20 minutes. .

  Thereafter, the reslurry liquid was filtered, and when the liquid level of the filtrate on Nutsche fell and the surface of the wet cake appeared, it was washed with ion exchange water at 40 ° C., which is 10 mass times the solid content (toner base particles). .

(Drying process)
Thereafter, the wet cake was collected, transferred to a “flash jet dryer” (manufactured by Seishin Enterprise Co., Ltd.), and dried until the water content became 0.1% by mass to prepare “toner base particles 1”.

(External addition process)
1% by mass of hydrophobic silica (number average primary particle size = 12 nm) and 0.3% by mass of hydrophobic titania (number average primary particle size = 20 nm) are added to the toner base particle 1 and mixed with a Henschel mixer. Thus, “Toner 1” was produced.

<Preparation of Toner 2>
In the solid-liquid separation / washing process for preparation of toner 1, quaternary ammonium salt (tetrabutylammonium fluoride dihydrate) 3 is added without adding an aqueous solution in which 3 parts by mass of sodium chloride is dissolved in 12 parts by mass of ion-exchanged water. “Toner 2” was prepared in the same manner except that an aqueous solution in which 12 parts by mass of ion-exchanged water was dissolved was added.

<Preparation of Toner 3>
In the solid-liquid separation / washing process for preparation of toner 1, 1M (mol / L) aqueous sodium hydroxide solution was added dropwise instead of 1M (mol / L) hydrochloric acid to adjust the pH to 10.0; “Toner 3” was prepared in the same manner except that an aqueous solution prepared by dissolving 3 parts by mass in 12 parts by mass of ion-exchanged water was not added.

<Preparation of Toner 4>
In the solid-liquid separation / washing process for preparation of toner 1, quaternary ammonium salt (tetrabutylammonium fluoride dihydrate) 1 is used without adding an aqueous solution in which 3 parts by mass of sodium chloride is dissolved in 12 parts by mass of ion-exchanged water. “Toner 4” was prepared in the same manner except that an aqueous solution in which 5 parts by mass was dissolved in 12 parts by mass of ion-exchanged water was added.

<Preparation of Toner 5>
In the solid-liquid separation / washing process for the production of toner 1, quaternary ammonium salt (tetrabutylammonium fluoride dihydrate) 0 is added without adding an aqueous solution in which 3 parts by mass of sodium chloride is dissolved in 12 parts by mass of ion-exchanged water. “Toner 5” was prepared in the same manner except that an aqueous solution in which 6 parts by mass was dissolved in 12 parts by mass of ion-exchanged water was added.

<Preparation of Toner 6>
The resin particles A used in the step of preparing the dispersion of toner base particles for the production of the toner 1 were changed to the resin particles B, and 3 parts by mass of sodium chloride in the solid-liquid separation / aggregation step was 12 parts by mass of ion-exchanged water. “Toner 6” was prepared in the same manner except that the aqueous solution dissolved in was not added.

<Preparation of Toner 7>
The resin particles A used in the step of preparing the dispersion of toner base particles for the production of the toner 1 were changed to the resin particles B, and 3 parts by mass of sodium chloride in the solid-liquid separation / aggregation step was 12 parts by mass of ion-exchanged water. “Toner” was similarly added except that an aqueous solution in which 0.6 parts by mass of a quaternary ammonium salt (tetrabutylammonium fluoride dihydrate) was dissolved in 12 parts by mass of ion-exchanged water was added without adding an aqueous solution dissolved in 7 "was produced.

<Preparation of Toner 8>
In the solid-liquid separation / washing process for preparation of toner 1, 1M hydrochloric acid was added dropwise to adjust the pH to 4.0, and an aqueous solution in which 3 parts by mass of sodium chloride was dissolved in 12 parts by mass of ion-exchanged water was added. “Toner 8” was prepared in the same manner except that this was not done.

<Preparation of Toner 9>
“Toner 9” was prepared in the same manner except that, in the solid-liquid separation / washing process of preparation of toner 1, an aqueous solution in which 3 parts by mass of sodium chloride was dissolved in 12 parts by mass of ion-exchanged water was not added.

<Preparation of Toner 10>
The resin particles A used in the step of preparing the dispersion of toner base particles for the production of the toner 1 were changed to the resin particles C, and 3 parts by mass of sodium chloride in the solid-liquid separation / washing step was 12 parts by mass of ion-exchanged water. “Toner 10” was prepared in the same manner except that the aqueous solution dissolved in was not added.

  Table 2 shows toner production (resin particles, salt at the time of washing, pH at the time of washing), and toner characteristics (hydrophobicity, remaining amount of surfactant).

  The degree of hydrophobicity and the remaining amount of the surfactant are values obtained by measurement by the above method.

<Production of developer>
100 parts by mass of ferrite core and 5 parts by mass of copolymer resin particles of cyclohexyl methacrylate / methyl methacrylate (copolymerization ratio 5/5) are put into a high-speed mixer equipped with stirring blades and stirred and mixed at 120 ° C. for 30 minutes. Then, a resin coat layer was formed on the surface of the ferrite core by the action of mechanical impact force to obtain a carrier having a volume-based median diameter of 40 μm.

  The volume-based median diameter of the carrier was measured by a laser diffraction particle size distribution measuring apparatus “HELOS” (manufactured by Sympathic) equipped with a wet disperser.

  "Toners 1 to 10" are added to the carrier so that the toner concentration is 6% by mass, and the mixture is put into a micro-type V-type mixer (Tsutsui Rikenki Co., Ltd.), mixed for 30 minutes at a rotation speed of 45 rpm Developers 1 to 10 "were prepared.

<Performance evaluation>
(Image forming device)
As an image forming apparatus, a commercially available color multifunction peripheral “bizhub PRO C6500 (manufactured by Konica Minolta Business Technologies, Inc.)” (print speed: 65 sheets / 1 minute, A4 size lateral feed) was prepared.

(Change in solid image density)
Charging rise was evaluated by solid image density change (density followability).

To change the solid image density, the toner and the developer prepared above are sequentially loaded into the developing device of the image forming apparatus, and the amount of adhered toner is 4.5 g / m ^{2 on} the high-quality paper (65 g / m ² ) of A4 size. The solid images were printed continuously at 1, 100, 500, and 2000 sheets in an environment of normal temperature and normal humidity (20 ° C., 50% RH), and the density change of each printed image was measured.

  The change in solid image density is evaluated by the density difference between the 100th print and 2000th print, and a change with an image density of 0.1 or less is regarded as acceptable.

(Cover of image)
In the image fogging, the above-prepared toner and developer are sequentially loaded into the developing device of the image forming apparatus, and a document with a printing rate of 5% is placed on a high-quality paper (65 g / m ² ) of A4 size at room temperature and normal humidity (20 The evaluation was based on the difference between the fog density of the plain image after the printing of 100,000 sheets and the white paper density of the transfer material in an environment of 50 ° C. and 50% RH.

  The white paper density of the transfer material is measured at 20 locations of A4 size, and the average value is defined as the white paper density.

  The fog density of a plain image after printing 100,000 sheets is measured at 20 locations of A4 size, and the average value is defined as the fog density. Density measurement was performed using a reflection densitometer “RD-918 (manufactured by Macbeth)”. In the evaluation, ◎ and ○ are acceptable.

Evaluation criteria A: Image fog is less than 0.003, good ○: Image fog is 0.003 or more and less than 0.010, practically no problem ×: Image fog density is 0.010 or more, practical problem Level that becomes.

(Toner scattering)
The toner scattering was evaluated based on the contamination with scattered toner on the upper part of the developing unit of the image forming apparatus.

  Using the above image forming apparatus, after the printing of 100,000 originals with a printing rate of 5%, the stain on the upper part of the developing unit of the image forming apparatus was visually observed and evaluated. In addition, the evaluation is ◎ and ○ are acceptable.

Evaluation criteria A: No stain on the upper part of the developing unit is seen. Even if the user replaces the developing unit, the hands are not soiled at all. ○: Slight dirt due to the scattered toner is seen on the upper part of the developing device. Even if the user replaces the developing unit, the hand is not dirty at all. Δ: The toner is scattered on the upper part of the developing unit. When the user replaces the developing unit, the hands are slightly stained. X: Many stains due to the toner scattered on the upper part of the developing device are observed, and the user recognizes the stain so that hand washing is required after replacing the developing unit.

  Table 3 shows the evaluation results.

  As shown in Table 3, “Toners 1 to 7” of Examples 1 to 7 are excellent in the followability (charging rise) of solid image density, have no problem with image fog and toner scattering, and have the object or effect of the present invention. You can see that it has been achieved. On the other hand, it can be seen that the “toners 8 to 10” of Comparative Examples 1 to 3 have a problem in any of the evaluation items and the purpose or effect is not achieved.

1Y, 1M, 1C, 1K photoconductor 2Y, 2M, 2C, 2K charging means 3Y, 3M, 3C, 3K exposure means 4Y, 4M, 4C, 4K developing means,
5Y, 5M, 5C, 5K Primary transfer roller 6Y, 6M, 6C, 6K Cleaning means 10Y, 10M, 10C, 10K Image forming unit

Claims (3)

An electrostatic charge image developing toner, comprising at least a binder resin and a colorant, wherein the electrostatic charge image developing toner has a hydrophobicity of 30% or less. 2. The electrostatic image developing toner according to claim 1, wherein the amount of the surfactant contained in the electrostatic image developing toner is 0.1% by mass or more and 1.0% by mass or less. 3. The toner for developing an electrostatic charge image according to claim 1, wherein the toner is produced through a process of aggregating and fusing at least resin particles and a colorant in an aqueous medium.

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