JP2012189940A - Toner for electrostatic charge image development and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide toner for electrostatic charge image development that exhibits excellent durability during storage or in a developing device without impairing low-temperature fixability, and an image forming method using the toner.SOLUTION: Toner for electrostatic charge image development with a core-shell structure includes a core layer containing at least a binder resin and a mold release agent, and a shell layer. A resin layer that forms the shell layer is formed of latex prepared by seed polymerization with resin fine particles having composition different from that of the main binder resin of the layer as a core.

Description

  The present invention relates to a toner for developing an electrostatic image (hereinafter also simply referred to as toner) used in an electrophotographic image forming apparatus and the like, and an image forming method using the toner.

  In recent years, in response to the trend toward energy saving and resource saving in society as a whole, in electrophotographic technology, there is an increasing need to reduce the amount of power consumed by the entire image forming apparatus and the amount of waste.

  From the above viewpoint, when the image forming apparatus based on the electrophotographic technology is viewed as a whole, the amount of power consumed by the fixing device is large, and it is possible to reduce the amount of power by lowering the fixing temperature. As a big occupancy. In order to save resources, it is effective to reduce the amount of developer discarded by extending the life of the developer.

  Furthermore, in recent years, with the speeding up of image forming apparatuses, especially the speed of color image forming apparatuses, it has become necessary to store a large amount of developer for a long period of time, and the agitation strength in the developing device has increased, resulting in greater stress on the developer. As a result, the deterioration of the toner was promoted, and the charge amount and the external additive were buried significantly as the toner was crushed. There is a need to develop a toner for developing an electrostatic image that is extremely durable even under these harsh conditions and can achieve a long life of the developer.

  However, the low-temperature fixability of the toner and the durability during storage or in the developing device are incompatible with each other, and conventionally, it has not been possible to provide both of them with high performance.

  For example, there is an invention in which a core-shell type toner is used and the shell layer resin has a Tg higher than that of the core resin and is covered as uniformly as possible. However, there is a limit to improving low-temperature fixability (Patent Document 1).

  In another invention, fluorine acrylate resin fine particles are fixed to the toner surface to give low-temperature fixability and good chargeability, and to improve durability during storage or in a developing device. Yes (Patent Document 2). However, the low-temperature fixability of the toner and high durability during storage or in the developing device have not been obtained.

JP 2009-204669 A JP 2009-2551092 A

  The present invention has been made to solve the above problems.

  That is, an object of the present invention is to provide an electrostatic charge image developing toner excellent in durability during storage or in a developing device without impairing the low-temperature fixability, and an image forming method using the toner. is there.

  The object of the present invention is achieved by adopting the following configuration.

(1)
A core-shell structured toner for developing electrostatic images having a core layer containing at least a binder resin and a release agent, and a shell layer, wherein the resin layer forming the shell layer is a main binder resin of the shell layer. Is a toner for developing an electrostatic charge image, wherein the toner is formed from a latex produced by seed polymerization using fine resin particles having different compositions as nuclei.

(2)
When the glass transition temperature of the binder resin forming the shell layer is Tg1, the glass transition temperature of the resin forming the resin fine particles contained in the shell layer is Tg2, and the glass transition temperature of the core forming resin is Tg3,
35 ≦ Tg1 ≦ 50
65 ≦ Tg2 ≦ 85
20 ≦ (Tg2−Tg1) ≦ 45
35 ≦ Tg3 ≦ 45
(However, all temperature units are expressed in ° C)
(1) The electrostatic image developing toner according to (1).

(3)
The solubility parameter (hereinafter also referred to as SP value) of the binder resin that forms the shell layer is SP1, the SP value of the resin that forms the resin fine particles contained in the shell layer is SP2, and the SP value of the core-forming resin is SP3. If the difference between SPx and SPy is Δx, y,
0.2 ≦ Δ1, 2 ≦ 1.0
0 ≦ Δ1, 3 ≦ 0.1
(However, the unit of the value is (cal / cm ³ ) ^1/2 )
(1) The electrostatic image developing toner according to (1).

(4)
The electrostatic charge image developing toner according to any one of (1) to (3) is charged by stirring, an unfixed toner image formed by developing an electrostatic latent image is transferred to an image support, and then heated. An image forming method comprising fixing.

  According to the present invention, it is possible to provide an electrostatic image developing toner excellent in durability during storage or in a developing device and an image forming method using the toner without impairing the low-temperature fixability.

FIG. 3 is a schematic diagram illustrating an internal configuration of a toner for developing an electrostatic image according to the present invention. 1 is a cross-sectional configuration diagram illustrating an example of an image forming apparatus used in the present invention. 1 is a configuration diagram showing an example of a heat fixing device used in an image forming apparatus according to the present invention.

  In the present invention, when producing the shell-forming resin, for example, high glass transition point (Tg) resin fine particles (hereinafter sometimes referred to as “nuclear particles”) are added as seed polymerization nuclei during the polymerization step. As a result, the toner of the present invention contains resin fine particles having excellent heat resistance in the shell, and has higher performance than conventional toners in terms of low-temperature fixability and heat resistance.

  That is, the toner of the present invention is formed through a process of aggregating latex, has a core layer containing at least a binder resin and a release agent, and the binder resin layer forming the shell layer is formed of the binder resin. Is characterized in that it is formed from latex produced by seed polymerization using resin core particles having different compositions.

  In the present invention, the seed polymerization core particles contained in the shell layer have the effect of increasing the durability of the toner during storage, and the softening point of the binder resin forming the core particles can be lowered. It was found that the low-temperature fixability can be improved.

Further, when the glass transition temperature of the binder resin forming the shell layer is Tg1, the glass transition temperature of the resin forming the resin fine particles contained in the shell layer is Tg2, and the glass transition temperature of the core forming resin is Tg3. ,
35 ≦ Tg1 ≦ 50
65 ≦ Tg2 ≦ 85
further,
20 ≦ (Tg2−Tg1) ≦ 45
35 ≦ Tg3 ≦ 45
(However, all temperature units are expressed in ° C)
The toner is preferably.

  The film thickness of the shell layer is usually 30 to 800 nm, and a very thin film or additive may be adhered to this surface. Further, it is desirable that the toner has a volume average particle diameter of 3 to 10 μm.

  The reason why the toner of the present invention exhibits high heat resistance and, as a result, has high durability during storage and in the developing device, is that the shell layer is formed from a latex made by seed polymerization. Let's go. That is, resin fine particles having a relatively high glass transition temperature (Tg) serving as a nucleus of seed polymerization function as a filler in the shell layer, and the heat resistance strength of the layer can be kept high as compared with the case where no resin fine particles are present. This will increase the durability during storage and in the developer. This is presumably because seed polymerization core particles having a high glass transition temperature (Tg) are arranged outside the toner particle shell layer (on the toner particle surface side) while maintaining affinity with the shell resin. Further, when the SP values of the high Tg resin fine particles and the shell binder resin are separated from each other, they are not compatible with each other and can exhibit individual properties independently.

  However, when it is not the core of seed polymerization, that is, when a resin for a shell mixed with resin fine particles is prepared by, for example, post-mixing the same high Tg resin fine particles, the resin fine particles are formed in the shell layer due to their low compatibility. Such an effect cannot be obtained because it is oriented too much on the surface. In addition, when the high Tg resin fine particles and the shell binder resin are close in composition, they are compatible when covering the core particle surface layer, resulting in a mixture having an intermediate property, and the desired effect is It is estimated that it is difficult to obtain. In the case of the present invention, the resin particles present in the shell resin are coated with the core particles in a state of being encapsulated in the shell resin particles by using seed polymerization described later. It can be present in the toner particles. This will be an indispensable condition for obtaining the effect of the present invention.

  That is, although the above phenomenon has not been analyzed in detail, the reason why the toner of the present invention has a high resistance to blocking during storage and agitation durability in the developing device, despite the good low-temperature fixability, is as follows. Is guessed.

  FIG. 1 is a schematic drawing of the configuration inside the core-shell toner particles of the present invention. Here, the shell layer 2 of the toner particles 1 is formed of a binder resin for the shell layer, and a charge control agent or the like is added as necessary. 3 is a seed polymerization core particle, which has a lower affinity with the binder resin or the like forming the core part (core particle) 4, and is therefore present more in the outer side than in the shell layer. Distributed on the particle surface. However, the binder resin for the shell layer also has a relationship in which the polymerization starts from the surface of the core particle, and at least a part of the binder resin is firmly attached to the surface of the core particle, so the affinity between the core particle surface and the shell resin is strong. .

  Moreover, since the binder resin for the shell layer is usually selected in the core-shell toner so as to have a strong affinity for the resin forming the core layer, the adhesive force at the interface between the core layer and the shell layer can be increased. This would give the toner high durability against thermal and mechanical stresses during storage and development stirring, as predicted from the properties of the binder resin and seed particles.

  On the other hand, when a higher temperature and pressure are applied simultaneously and suddenly than during storage, such as during heat fixing, the binder resin layer that forms the shell layer is not affected by the main binder resin for the shell. In order to receive stronger, it will soften rapidly and increase fluidity, so that it will be firmly fixed on an image support such as recording paper.

[Method for forming resin fine particles (core particles)]
The resin fine particles (nuclear particles) in the present invention are resin fine particles that become the core of the seed polymerization when a polymer that forms the shell resin layer is synthesized.

  In the present invention, it is necessary that the material does not melt or soften even when a little heat load is applied. Therefore, it is preferable to select a glass transition temperature (Tg) that is considerably higher than other toner binder resins, particularly a shell constituent resin. Specifically, the glass transition temperature is preferably 65 ° C. or higher, and the upper limit is preferably about 85 ° C.

  In the present invention, the core particles can be encapsulated in a resin having low compatibility without having a special composition or structure in order to form a shell resin by a method described later. Accordingly, the core particle in the present invention is not particularly limited as long as it can achieve the above Tg, and a known binder resin can be used. In the polymerizable monomer for forming the binder resin, Is not particularly limited.

[Method for forming resin for shell]
The shell resin in the present invention is a polymer having a double structure formed by using a polymerization method generally called seed polymerization.

  Seed polymerization is a polymerization method in which another particle serving as a nucleus is added in advance during the polymerization reaction, and the polymerization reaction is performed on the particle surface. The main purpose of using this method is to adjust the particle size and particle size distribution to an arbitrary range by adsorbing the surfactant only on the surface of the core particle (seed particle) and using it as a polymerization reaction field. However, in the present invention, the resin particles having low compatibility are used for encapsulating the resin in the shell.

  That is, if core particles having low compatibility with the main resin for the shell layer are separately formed in advance and the main resin is produced by performing a new polymerization reaction on the surface of the particles, the core resin is compatible with the main resin for the shell layer. Core particles that cannot be mixed due to low solubility can be included in the resin particles for the shell.

  At this time, the size of the seed polymerization core particles is about 10 to 1000 nm, more preferably about 50 to 500 nm, and preferably occupies 5 to 20 mass% of the entire shell layer forming resin. The main resin forming the shell layer is a resin formed by seed polymerization, and preferably occupies at least 50% by mass, particularly preferably 75 to 95% by mass of the shell layer mass.

  At this time, since the composition of the seed polymerization core particles and the polymerization reaction of the shell resin are completely separate reactions, there is no particular requirement for the core particles to be included in the shell resin, and an arbitrary one can be included.

  Further, the core layer containing at least a binder resin and a release agent is the above-described core particle coated on the shell layer, and this may be a resin particle having a multilayer structure or a sea-island structure, or Even if it is a single layer, the whole may be formed of a mixture of resins having different compositions. In that case, the resin having the largest content usually has a great influence on the physicochemical properties of the core particles. The glass transition temperature and the like of the resin to be described later can be represented by the most mixed resin.

[Tg measurement method]
In the present invention, the glass transition temperature can be measured and calculated using a known glass transition temperature measuring method.

  Here, a procedure for measuring the glass transition temperature using a differential scanning calorimeter, which is one of the typical methods for measuring the glass transition temperature, will be described. The glass transition temperature can be measured using, for example, a DSC-7 differential scanning calorimeter (manufactured by PerkinElmer) or a TAC7 / DX thermal analyzer controller (manufactured by PerkinElmer).

  As a measurement procedure, 5.0 mg of toner is precisely weighed to two digits after the decimal point, sealed in an aluminum pan (KITNO.0219-0041), and set in a DSC-7 sample holder. The reference was an empty aluminum pan.

  As measurement conditions, the measurement temperature is 0 to 200 ° C., the temperature increase rate is 10 ° C./min, the temperature decrease rate is 10 ° C./min, and the heat-cool-heat control is performed, and the analysis is performed based on the data in the 2nd Heat. went.

  The glass transition temperature draws an extension of the baseline before the rise of the first endothermic peak and a tangent line indicating the maximum slope between the rise of the first peak and the peak apex, and the intersection is taken as the glass transition point. Show.

  Further, as a method for calculating the glass transition temperature, the following method for calculating the theoretical glass transition temperature can also be mentioned. The theoretical glass transition temperature is calculated by multiplying the glass transition temperature when each component constituting the copolymer resin forms a homopolymer by the respective composition mass fraction, that is, by weighted averaging.

  That is, the theoretical glass transition temperature Tg (referred to as absolute temperature Tg ′) is calculated from the following formula (1) using the glass transition temperature of the homopolymer of the component constituting the copolymer resin.

Formula (1): 1 / Tg ′ = W1 / T1 + W2 / T2 +... + Wn / Tn
(Wherein W1, W2,... Wn is the mass fraction of each polymerizable monomer with respect to the total polymerizable monomer constituting the copolymer resin, and T1, T2,... Tn are each polymerizable. (The glass transition temperature (absolute temperature) of a homopolymer formed using a monomer is shown.)
[Monomer for binder resin for core or shell]
The binder resin for core or shell according to the present invention (hereinafter also simply referred to as a resin) contains a polymer obtained by polymerizing at least one polymerizable monomer as a constituent component. Examples of the monomer include vinyl monomers as shown in the following (1) to (10). That is,
(1) Styrene or styrene derivatives Styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert- Butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, etc. (2) Methacrylate derivatives Methyl methacrylate, methacryl Ethyl acetate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethyl methacrylate (3) Acrylic acid ester derivatives Methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, phenyl acrylate, etc. (4) Olefins Ethylene, propylene, isobutylene, etc. (5) Vinyl esters Vinyl propionate, vinyl acetate, vinyl benzoate, etc. (6) Vinyl ether (7) Vinyl ketones Vinyl methyl ketone, vinyl ethyl ketone, vinyl hexyl ketone, etc. (8) N-vinyl compounds N-vinyl carbazole, N-vinyl indole, - vinylpyrrolidone (9) vinyl compounds vinyl naphthalene, vinyl pyridine and the like (10) acrylic acid or methacrylic acid derivative acrylonitrile, methacrylonitrile, acrylamide.

  Moreover, it is also possible to use combining the polymerizable monomer which has an ionic dissociation group as a polymerizable monomer which comprises resin. Examples of the ionic dissociation group include substituents such as a carboxyl group, a sulfonic acid group, and a phosphoric acid group, and the polymerizable monomer having an ionic dissociation group has these substituents.

  Specific examples of the polymerizable monomer having an ionic dissociation group are given below.

  Acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumaric acid, maleic acid monoalkyl ester, itaconic acid monoalkyl ester, styrene sulfonic acid, allyl sulfosuccinic acid, 2-acrylamido-2-methylpropane sulfone Acids, acid phosphooxyethyl methacrylate, 3-chloro-2-acid phosphooxypropyl methacrylate, and the like.

  Furthermore, it is also possible to use a polyfunctional vinyl as a polymerizable monomer constituting the resin to obtain a resin having a crosslinked structure. Specific examples of the polyfunctional vinyls are listed below.

  That is, there are divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, neopentyl glycol diacrylate, and the like.

  Moreover, as a polyester-type resin, what was obtained by the polycondensation and copolycondensation of a polyhydric alcohol component and a polyhydric carboxylic acid component can be used.

[Characteristics of binder resin forming core layer and shell layer]
In the present invention, it is preferable that the binder resin forming the shell layer in the toner is not compatible with the resin of the core layer, and that the resin forming the shell has sufficient adhesiveness with the core.

  In order for the resin forming the shell to exhibit incompatibility with the core, the solubility parameter value of the resin forming the shell (hereinafter referred to as “SP value”) and the solubility parameter of the resin forming the core This is realized by setting the difference between values within an appropriate range.

  The solubility parameter value (SP value) is a numerical value representing the magnitude of the cohesive energy of the substance. According to the method proposed by Ferors, “Polym. Eng. Sci., Vol 14, P 147 (1974)”, evaporation of atoms or atomic groups When the energy and the molar volume are Δer and Δvi, respectively, the solubility parameter σ of the binder resin is calculated by the following formula (2).

Formula (2): σ = (ΣΔer / ΣΔvi) ^1/2
Moreover, the solubility parameter value of each vinyl copolymer is calculated by the product of the solubility parameter value of each component and the molar ratio. For example, assuming that the copolymer resin is composed of two types of monomers, X and Y, the mass composition ratio of each monomer is x, y (mass%), the molecular weight is Mx, My, When the solubility parameter values are SPx and SPy, the monomer ratios are X / Mx (mol%) and y / My (mol%). Here, when the molar ratio of the copolymer resin is C, it is expressed as C = x / Mx + y / My, and the solubility parameter value SP of the copolymer resin is represented by the following formula (3).

Formula (3): SP = [(x × SPx / Mx) + (y × Spy / My)] × 1 / C
In addition, for an overview of the solubility parameter of the polymer material, the solubility parameter item (http://polymer.nims.go.jp) provided in the database “InfoInfo” (http://polymer.nims.go.jp) provided by the National Institute for Materials Science //Polymer.nims.go.jp/guide/guide/p5110.html).

[Other toner materials]
Next, materials other than the binder resin used when producing the toner according to the present invention, that is, a colorant, wax, and external additive will be described.

  As the colorant that can be used in the toner according to the present invention, known colorants can be used, and specific colorants are listed below.

  Examples of the black colorant include carbon black such as furnace black, channel black, acetylene black, thermal black, and lamp black, and magnetic powder such as magnetite and ferrite can also be used.

  Examples of the colorant for magenta or red include C.I. I. Pigment Red 2, 3, 5, 6, 7, 15, 15, 48: 1, 53: 1, 57: 1, 60, 63, 64, 68, the same 81, 83, 87, 88, 89, 90, 112, 114, 122, 123, 139, 144, 149, 150, 163, 166, 170, 177, 178, 184, 202, 206, 207, 209, 222, 238, 269, and the like.

  Examples of the colorant for orange or yellow include C.I. I. Pigment Orange 31 and 43, C.I. I. Pigment Yellow 12, 14, 15, 17, 74, 83, 93, 94, 138, 155, 162, 180, 185, and the like.

  Further, as a colorant for green or cyan, C.I. I. Pigment Blue 2, 3, 15, 15, 15: 2, 15: 3, 15: 4, 16, 17, 17, 60, 62, 66, C.I. I. Pigment Green 7 etc.

  Examples of the dye include C.I. I. Solvent Red 1, 49, 52, 58, 63, 111, 122, C.I. I. Solvent Yellow 2, 6, 14, 15, 16, 19, 21, 21, 33, 44, 56, 61, 77, 79, 80, 81, 82, the same 93, 98, 103, 104, 112, 162, C.I. I. Solvent Blue 25, 36, 60, 70, 93, 95, etc.

  These colorants can be used alone or in combination of two or more as required. Further, the amount of the colorant added is in the range of 1 to 30% by mass, preferably 2 to 20% by mass, based on the whole toner, 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.

  As a method for adding the colorant, the resin fine particles are added at the stage of agglomeration by the addition of the flocculant to color the polymer. The colorant can also be used by treating the surface with a coupling agent or the like.

Next, the wax that can be used for the toner according to the present invention will be described. Examples of the wax that can be used in the toner according to the present invention include conventionally known waxes, and specific examples include the following. That is,
(1) Long-chain hydrocarbon waxes There are polyolefin waxes such as polyethylene wax and polypropylene wax, paraffin wax, and sazol wax.
(2) Ester wax Trimethylolpropane tribehenate, pentaerythritol tetramyristate, pentaerythritol tetrastearate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerine tribehenate, 1,18 -Octadecanediol distearate, tristearyl trimellitic acid, distearyl maleate and the like.
(3) Amide wax Ethylenediamine dibehenylamide, trimellitic acid tristearylamide, and the like.
(4) Dialkyl ketone waxes etc. There are distearyl ketones and the like.
(5) Others Carnauba wax, montan wax, etc.

  The melting point of the wax is usually 40 to 160 ° C, preferably 50 to 120 ° C, more preferably 60 to 90 ° C. 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 even when fixing at a low temperature. Further, the wax content in the toner is preferably 1% by mass to 30% by mass, and more preferably 5% by mass to 20% by mass.

[Toner Production Method]
As a typical method for producing the toner according to the present invention, for example, emulsification in which fine particles of resin formed in an aqueous medium containing a surfactant are aggregated and fused in an aqueous medium to produce a toner. There is a method called the meeting method. In the emulsion association method, toners with uniform particle diameters and shapes can be more reliably produced, so toners used for digital image formation with high fine line reproducibility and fine dot image formation opportunities are produced. The above is also preferable.

The toner production method by the emulsion association method is performed, for example, through the following steps. That is,
(1) Dissolution / dispersion step for dissolving or dispersing wax in radical polymerizable monomer (2) Polymerization step for preparing resin particle dispersion (3) Aggregating resin particles and colorant particles in an aqueous medium Aggregating and fusing step for forming aggregated particles to be toner base particles by fusing (4) aging step for aging associated particles by thermal energy to adjust the shape (5) from cooled aggregated particle dispersion Washing step for solid-liquid separation of the associated particles and removing the surfactant and the like from the associated particles (6) Drying step for drying the washed associated particles, and if necessary, after the drying step,
(7) A step of adding an external additive to the dried association particles. The above steps will be described in detail later.

  The associating particles serving as a toner base are produced by a production method in which resin particles and colorant particles are aggregated and fused. The shape of the associated particles can be controlled, for example, by controlling the heating temperature in the aggregation / fusion process and the heating temperature and time in the first aging process.

  Among these, time control in the aging process is the most effective. Since the ripening step is intended to adjust the circularity of the associated particles, the target circularity is reached by controlling this time.

  The associated particles serving as a toner base can be preferably prepared by, for example, salting out / fusion performed in the following procedure. That is, after the wax component is dissolved or dispersed in the polymerizable monomer that forms the resin, it is mechanically dispersed in an aqueous medium, and the polymerizable monomer is polymerized by a mini-emulsion polymerization method to obtain resin particles. Form. Then, the formed resin particles and colorant particles are salted out / fused as described later to form associated particles. In addition, the method of melt | dissolving a wax component in the above-mentioned polymerizable monomer can take any method, even if a wax component is melt | dissolved or fuse | melted.

  Further, in the shell layer according to the present invention, resin particles synthesized by seed polymerization are used as the shell resin, and specific examples thereof are described in Examples described later.

  The shelling step is a step of controlling the final toner shape and particle size, but the resin particles for the shell are added under the same conditions to each core particle. It is preferable that the diameter and shape are uniform. If the core particles have the same particle size and shape, the toner particles having the same shape and size are formed while the shell-forming resin particles are easily uniformly adhered to the surface, and a shell having a uniform thickness is formed. Particles can be produced reliably.

  Hereinafter, each manufacturing process of the toner by the emulsion association method will be described.

(1) Dissolution / dispersion step In this step, a radical polymerizable monomer solution forming a binder resin is mixed and dissolved to prepare a radical polymerizable monomer solution. The dispersion treatment is carried out so that the monomer solution is put into droplets having a predetermined particle diameter in the aqueous medium by being put into the aqueous medium. In mixing the radical polymerizable monomer, in addition to mixing and dissolving a plurality of types of polymerizable monomers, an operation of adding a wax or the like and dissolving it in the radical polymerizable monomer solution is also performed.

(2) Polymerization step In a preferred example of this polymerization step, a radical polymerizable monomer solution in which a wax is dissolved or dispersed in an aqueous medium containing a surfactant having a critical micelle concentration (CMC) or less is added. Then, mechanical energy is applied to form droplets, and then a water-soluble radical polymerization initiator is added to advance the polymerization reaction in the droplets. Note that 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 means for applying mechanical energy include means for applying strong stirring or ultrasonic vibration energy such as homomixer, ultrasonic wave, and manton gorin.

  By this polymerization step, resin particles containing a wax and a binder resin are produced. Such resin particles may be either colored particles or non-colored particles. The colored resin particles can be produced by polymerizing a monomer composition containing a colorant. In addition, when a toner is prepared using resin particles that are not colored, a dispersion of colorant particles is added to the dispersion of resin particles in the aggregation / fusion process described below, and the resin particles and the colorant particles are combined. By fusing, toner base particles called association particles are produced.

(3) Aggregation / fusion process In this aggregation / fusion process, a specific method for aggregating and fusing the resin particles (colored or non-colored resin particles) obtained by the polymerization process is salting out / fusion. The method is preferred. In the agglomeration / fusion step, it is possible to agglomerate and fuse internal additive particles such as wax particles and charge control agents together with resin particles and colorant particles.

  Here, “salting out / fusion” means that the aggregation and fusion of resin particles and the like proceed in parallel, and when the particles grow to a desired particle size, an aggregation terminator is added to stop the particle growth. In order to control the particle shape as needed, heating is continued.

  Further, the “aqueous medium” in the aggregation / fusion process refers to a material in which the main component (50% by mass or more) is made of water. Examples of components other than water include organic solvents that dissolve in water, and examples include methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, and tetrahydrofuran.

  The colorant particles can be prepared by dispersing the colorant in an aqueous medium. 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.

  Examples of the surfactant used in the aqueous medium include the same surfactants as those described above. The colorant (particle) may be a surface-modified one. In the surface modification method of the colorant, the colorant is dispersed in a solvent, the surface modifier is added to the dispersion, and the system is reacted by raising the temperature. After completion of the reaction, the colorant is separated by filtration, washed and filtered with the same solvent, and dried to obtain a colorant (pigment) treated with the surface modifier.

  The salting-out / fusion method, which is a preferred agglomeration and fusion method, is a salting-out method comprising an alkali metal salt, an alkaline earth metal salt, a trivalent salt, etc. in water in which resin particles and colorant particles are present. A salting agent is added as a coagulant having a critical coagulation concentration or higher, and then the salting-out proceeds by heating to a temperature above the glass transition point of the resin particles and above the melting peak temperature (° C) of the mixture. At the same time, it is a step of performing fusion. Here, the alkali metal salt and the alkaline earth metal salt which are salting-out agents include lithium, potassium, sodium and the like as the alkali metal, and examples of the alkaline earth metal include magnesium, calcium, strontium and barium. Preferably, potassium, sodium, magnesium, calcium, and barium are used.

  When agglomeration and fusion are performed by salting out / fusion, it is preferable to make the time allowed to stand after adding the salting-out agent as short as possible. The reason for this is that depending on the standing time after salting out, the aggregation state of the particles may fluctuate and the particle size distribution may become unstable, or the surface properties of the fused particles may vary. This is because of concern. Moreover, it is preferable that the addition temperature of the salting-out agent is at least the glass transition temperature of the resin particles. The reason for this is that if the addition temperature of the salting-out agent is equal to or higher than the glass transition temperature of the resin particles, the salting-out / fusion of the resin particles proceeds rapidly, but it becomes difficult to control the particle size. This is because there are concerns about the occurrence of problems such as generation of particles having a particle size. A preferable range of the addition temperature of the salting-out agent is not higher than the glass transition temperature of the resin, but is generally 5 to 55 ° C, preferably 10 to 45 ° C.

  In addition, after adding the salting-out agent below the glass transition temperature of the resin particles, the temperature is raised as quickly as possible, and heated to a temperature that is equal to or higher than the glass transition temperature of the resin particles and equal to or higher than the melting peak temperature of the mixture. It is preferable to do. The time until this temperature rise is preferably less than 1 hour. Further, although it is necessary to quickly raise the temperature, the rate of temperature rise is preferably 0.25 ° C./min or more. The upper limit of the rate of temperature rise is not particularly specified, but if the temperature is raised rapidly, salting out proceeds rapidly, which may cause a problem that it is difficult to control the particle size. The following is preferred.

  By this agglomeration / fusion process, a dispersion liquid of associated particles obtained by salting out / fusion of resin particles and arbitrary particles is obtained.

(4) Ripening step Next, by controlling the heating temperature in the agglomeration and fusion step, particularly the heating temperature and time in the ripening step, the surface of the associated particles formed with a uniform particle size and a narrow distribution has a smooth but uniform shape. Control what you have. Specifically, the heating temperature is lowered in the aggregation / fusion process to suppress the progress of fusion between the resin particles to promote homogenization, the heating temperature is lowered in the first aging process, and the time The surface of the associated particles is controlled to have a uniform shape by increasing the length.

(4-1) Shelling Step When a core-shell toner is formed, a shelling step and a second ripening step for advancing the fusion of shell resin particles are added after the ripening step. In the shelling step, the resin particle dispersion for the shell is added to the associated particle dispersion that becomes the core particles, and the resin particles for the shell are aggregated and fused on the surface of the core particles. These resin particles are coated to form associated particles that serve as a base of toner particles.

  Specifically, the core particle dispersion is added with the dispersion of the resin particles for shells while maintaining the temperature in the aggregation / fusion process and the aging process, and slowly over several hours while continuing the heating and stirring. The resin particles for shell are coated on the surface of the core particles to form associated particles. The heating and stirring time is preferably 1 hour to 7 hours, particularly preferably 3 hours to 5 hours.

(4-2) Second ripening step After the shelling, the particle growth is stopped by adding a terminator such as sodium chloride at the stage where the associated particles have reached a predetermined particle size, and then adheres to the core particles. Heating and stirring are continued for several hours in order to fuse the shell resin particles. In the shelling step, a shell having a thickness of 100 to 300 nm is formed on the surface of the core particle. In this way, the resin particles are fixed to the surface of the core particles to form a shell, and rounded and uniform shaped particles can be formed.

  When producing a toner with a core-shell structure, the shape of the associated particles formed by setting the time of the second aging step longer or setting the aging temperature higher can be controlled in the true sphere direction. It is.

(5) Washing step In this step, first, the associated particle dispersion is cooled (rapidly cooled). As cooling process conditions, it can cool at the cooling rate of 1-20 degreeC / min, for example. The cooling treatment method is not particularly limited, and examples include known methods such as a method of cooling by introducing a refrigerant from the outside of the reaction vessel, and a method of cooling by directly introducing cold water into the reaction system. it can.

  Next, the associated particle dispersion liquid that has been subjected to the cooling treatment is subjected to solid-liquid separation, and the solid-liquid separated association particles are washed. That is, a toner cake (in a wet state) of associated particles formed by performing a solid-liquid separation process for solid-liquid separation of the associated particles from the associated particle dispersion liquid that has been cooled to a predetermined temperature by performing a cooling process. Adhesives such as surfactants and salting-out agents are removed from the aggregate of aggregated particles in a cake form). A typical example of the solid-liquid separation process is a filtration process. As a specific method of the filtration process, for example, a centrifugal separation method, a vacuum filtration method using Nutsche or the like, a filter press, or the like is used. There are filtration methods.

(6) Drying Step This step is a step in which the washed cake is crushed and dried to obtain dried association particles, that is, toner base particles. Examples of dryers that can be used in this process include known drying processors such as spray dryers, vacuum freeze dryers, and vacuum dryers, stationary shelf dryers, mobile shelf dryers, fluidized bed dryers, It is also possible to use a rotary dryer, a stirring dryer or the like. The water content of the dried association particles is preferably 5% by mass or less, and more preferably 2% by mass or less.

  In addition, when the aggregated particle | grains by which the drying process was carried out aggregated with the weak attractive force between particles, the aggregate can also be disintegrated. Specific examples of the crushing treatment apparatus include mechanical crushing treatment apparatuses such as a jet mill, a Henschel mixer, a coffee mill, and a food processor.

(7) External Addition Processing Step This step is a step of preparing toner particles by adding and mixing external additives as necessary to the dried association particles.

  The associated particles produced through the steps up to the drying step can be used as toner particles as they are, but are known on the surface of the associated particles from the viewpoint of improving charging performance, fluidity, and cleaning properties as a toner. It is preferable to add particles such as inorganic fine particles and organic fine particles as external additives.

  In addition, from the viewpoint of imparting fluidity, when mixing known inorganic fine particles, inorganic oxide particles such as silica, titania, and alumina are preferable. Furthermore, these inorganic fine particles are formed by a silane coupling agent, a titanium coupling agent, or the like. More preferably, it is hydrophobized.

(Developer)
Next, the developer using the toner according to the present invention will be described.

  The toner according to the present invention can be used for both a one-component developer (including magnetic and non-magnetic) that forms an image without using a carrier and a two-component developer that forms an image using a carrier. is there.

  When used as a two-component developer, it can be prepared by mixing toner and carrier. The mixing amount of the toner with respect to the carrier is preferably 2 to 10% by mass. The mixing apparatus for mixing the toner and the carrier is not particularly limited, and examples thereof include a Nauter mixer, a W cone, and a V-type mixer.

  The carrier is preferably a ferrite carrier having a volume average particle size of 10 to 60 μm and a saturation magnetization value of 20 to 80 emu / g. Thus, by using a carrier having a small carrier particle size and a low saturation magnetization value, the magnetic brush on the developing sleeve becomes soft, and an electrophotographic image with good sharpness can be formed.

  The volume average particle diameter of the carrier can be measured by, for example, a laser diffraction particle size analyzer “HELOS (manufactured by Shinpatec Corporation)” equipped with a wet disperser. The saturation magnetization can be measured by, for example, “DC magnetization characteristic automatic recording device 3257-35 (manufactured by Yokogawa Electric Corporation)”.

  It is preferable that the carrier has magnetic particles as a core (core) and the surface thereof is coated with a resin. The resin used for coating the carrier core material is not particularly limited, and various resins can be used. For the positively chargeable toner, for example, a fluorine-based resin, a fluorine-acrylic acid-based resin, a silicone-based resin, a modified silicone-based resin, or the like can be used, and a condensation type silicone-based resin is preferable. For negatively chargeable toners, for example, acrylic-styrene resins, mixed resins of acrylic-styrene resins and melamine resins and cured resins thereof, silicone resins, modified silicone resins, epoxy resins, polyesters Resin, urethane resin, polyethylene resin, etc. can be used. Among these, a mixed resin of an acrylic-styrene resin and a melamine resin, a cured resin thereof, and a condensation type silicone resin are preferable. If necessary, a two-component developer can be formed by adding a charge control agent, an adhesion improver, a primer treatment agent, a resistance control agent, and the like.

  When the toner is used as a non-magnetic one-component developer that forms an image without using a carrier, the toner is rubbed against and pressed against the charging member and the developing roller surface during image formation. Image formation by the non-magnetic one-component development method can simplify the structure of the developing device, and thus has an advantage that the entire image forming device can be made compact. Therefore, when the toner according to the present invention is used as a non-magnetic one-component developer, a full color print can be created with a compact color printer, and a full color print excellent in color reproducibility can be created even in a space-limited work environment. Is possible.

  A magnetic toner which is one of the one-component developers can be produced by using magnetic fine particles as a colorant. As the magnetic fine particles, particles such as ferrite and magnetite having an average primary particle diameter of 0.1 to 2.0 μm are used. The addition amount of the magnetic fine particles is preferably 20 to 70% by mass in the toner.

[Image forming apparatus used in image forming method]
Next, an image forming apparatus capable of forming an image using the toner according to the present invention will be described. FIG. 2 is a schematic view showing an example of an image forming apparatus that can be used when the toner according to the present invention is used as a two-component developer.

  In FIG. 2, 1Y, 1M, 1C and 1K are photoreceptors, 4Y, 4M, 4C and 4K are developing devices, 5Y, 5M, 5C and 5K are primary transfer rolls as primary transfer means, and 5A is a secondary transfer. Secondary transfer rolls as means, 6Y, 6M, 6C and 6K are cleaning devices, 7 is an intermediate transfer member unit, 24 is a heat roll type fixing device, and 70 is an intermediate transfer member.

  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 recording member P. An endless belt-shaped sheet feeding / conveying means 21 and a heat roll type fixing device 24 as a fixing means. 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 photoconductor, and a periphery of the photoconductor 1Y. A charging unit 2Y, an exposure unit 3Y, a developing unit 4Y, a primary transfer roll 5Y as a primary transfer unit, and a cleaning unit 6Y. An image forming unit 10M that forms a magenta image as another different color toner image is disposed around a drum-shaped photoconductor 1M as a first photoconductor, and the photoconductor 1M. A charging unit 2M, an exposure unit 3M, a developing unit 4M, a primary transfer roll 5M as a primary transfer unit, and a cleaning unit 6M.

  In addition, an image forming unit 10C that forms a cyan image as one of other different color toner images is disposed around the photoconductor 1C as a drum-type photoconductor 1C as a first photoconductor. The charging unit 2C, the exposure unit 3C, the developing unit 4C, the primary transfer roll 5C as the primary transfer unit, and the cleaning unit 6C are provided. Further, as one of the other different color toner images, the image forming unit 10K that forms a black image includes a drum-shaped photoconductor 1K as a first photoconductor, and a charge disposed around the photoconductor 1K. Means 2K, exposure means 3K, developing means 4K, primary transfer roll 5K as primary transfer means, and cleaning means 6K.

  The endless belt-like intermediate transfer body unit 7 has an endless belt-like intermediate transfer body 70 as an intermediate transfer endless belt-like second image carrier that is wound around a plurality of rolls and is rotatably supported.

  Each color image formed by the image forming units 10Y, 10M, 10C, and 10K is sequentially transferred onto the rotating endless belt-shaped intermediate transfer body 70 by the primary transfer rolls 5Y, 5M, 5C, and 5K, and is combined. A colored image is formed. A recording member P such as a sheet as a transfer material accommodated in the sheet feeding cassette 20 is fed by the sheet feeding / conveying means 21, passes through a plurality of intermediate rolls 22 A, 22 B, 22 C, 22 D, and a registration roll 23, and is secondary. A color image is transferred onto the recording member P at a time by being conveyed to a secondary transfer roll 5A as a transfer means. The recording member P to which the color image has been transferred is fixed by the heat roll type fixing device 24, is sandwiched by the paper discharge roll 25, and is placed on the paper discharge tray 26 outside the apparatus.

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

  During the image forming process, the primary transfer roll 5K is always in pressure contact with the photoreceptor 1K. The other primary transfer rolls 5Y, 5M, and 5C are in pressure contact with the corresponding photoreceptors 1Y, 1M, and 1C, respectively, only during color image formation.

  The secondary transfer roll 5A comes into pressure contact with the endless belt-shaped intermediate transfer body 70 only when the recording member P passes through the secondary transfer roll 5A and secondary transfer is performed.

  In this manner, 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 the recording member P is collectively collected. Then, the image is fixed and fixed by pressure and heating by the fixing device 24. The photoreceptors 1Y, 1M, 1C, and 1K after transferring the toner image to the recording member P are cleaned with the cleaning device 6A to remove the toner remaining on the photoreceptor, and then the above-described charging, exposure, and development cycle. The next image formation is performed.

[Fixing device]
FIG. 3 shows an example of a heat fixing device that can be used in the image forming apparatus, and FIG. 3- (A) shows a fixing device (type using a pressure roller and a heat roller) used in the present invention. It is sectional drawing which shows an example.

  The fixing device 10 includes a heating roller 71 and a pressure roller 72 in contact with the heating roller 71. Reference numeral 17 denotes a toner image formed on an image support (transfer material, transfer paper) P.

  The heating roller 71 has a coating layer 82 made of a fluororesin or an elastic body formed on the surface of the cored bar 81 and includes a heating member 75 made of a linear heater.

  The cored bar 81 is made of metal and has an inner diameter of 10 to 70 mm. Although it does not specifically limit as a metal which comprises the metal core 81, For example, metals, such as iron, aluminum, copper, or these alloys can be mentioned.

  The thickness of the cored bar 81 is 0.1 to 15 mm, and is determined in consideration of a balance between a request for energy saving (thinning) and strength (depending on the constituent materials). For example, in order to maintain the same strength as that of a cored bar made of iron of 0.57 mm with a cored bar made of aluminum, the wall thickness needs to be 0.8 mm.

  Examples of the fluororesin constituting the surface of the coating layer 82 include PTFE (polytetrafluoroethylene) and PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer).

  The thickness of the coating layer 82 made of a fluororesin is 10 to 500 μm, preferably 20 to 400 μm.

  When the thickness of the coating layer 82 made of the fluororesin is less than 10 μm, the function as the coating layer cannot be sufficiently exhibited, and the durability as the fixing device cannot be ensured. On the other hand, there is a problem that the surface of the coating layer exceeding 500 μm is easily scratched by paper dust, and toner or the like adheres to the scratched part, thereby causing image smearing.

  Further, as the elastic body constituting the covering layer 82, it is preferable to use silicon rubber, silicon sponge rubber or the like having good heat resistance such as LTV, RTV, HTV.

  The Asker C hardness of the elastic body constituting the covering layer 82 is less than 80 °, preferably less than 60 °.

  The thickness of the coating layer 82 made of an elastic body is preferably 0.1 to 30 mm, and more preferably 0.1 to 20 mm.

  As the heating member 75, a halogen heater can be preferably used.

  The pressure roller 72 is formed by forming a coating layer 84 made of an elastic body on the surface of the cored bar 83. The elastic body constituting the coating layer 84 is not particularly limited, and examples thereof include various soft rubbers such as urethane rubber and silicone rubber, and sponge rubber. The silicon rubber exemplified as the one constituting the coating layer 84 and It is preferable to use silicon sponge rubber.

  Moreover, 0.1-30 mm is preferable and, as for the thickness of the coating layer 84, 0.1-20 mm is more preferable.

  The fixing temperature (surface temperature of the heating roller 10) is preferably 70 to 210 ° C., and the fixing linear velocity is preferably 80 to 640 mm / sec. The nip width of the heating roller is set to 8 to 40 mm, preferably 10 to 30 mm.

  The heating roller may be used by applying 0.3 mg or less of silicon oil per print, but may be used without oil.

  The fixing device 10 shown in FIG. 3B is a type using a soft roller and a heating roller that secures a fixing nip and prevents the transfer material from being wound and has excellent image quality, and is heated as a heating roller member. A roller 601 and a soft roller 17b as a soft roller member are used, and a halogen lamp 14 as a heating member is provided inside the heating roller 601.

  A nip portion N is formed between the heating roller 601 and the soft roller 17b, and the toner image on the transfer material P is fixed by applying heat and pressure through the nip portion N. In the above, a halogen lamp 14 (not shown) as a heating member may be disposed inside the soft roller 17b.

[Image support (transfer paper)]
The image support used in the present invention is a support for holding a toner image and is usually called a transfer material or transfer paper. Specifically, plain paper from thin paper to thick paper, coated printing paper (such as glossy coated paper) such as art paper and coated paper, commercially available Japanese paper and postcard paper, OHP plastic film, cloth, etc. However, the present invention is not limited to these.

  Examples of the present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. In addition, what is described as “parts” in the following text represents “parts by mass”.

1. Preparation of Toner (1) -1 Preparation of “Resin Particle Dispersion A1” A resin particle dispersion of resin particles A1 was prepared according to the following procedure.

(A) First-stage polymerization A surfactant solution was prepared by dissolving 2 parts by mass of an anionic surfactant (polyoxy (2) dodecyl ether sulfate sodium salt) in 1100 parts by mass of ion-exchanged water. Moreover, after adding the following compound in the flask equipped with the stirring apparatus, it heated at 85 degreeC and prepared the monomer solution. That is,
Styrene 230 parts by weight n-butyl acrylate 103 parts by weight Methacrylic acid 19 parts by weight n-octyl mercaptan 4 parts by weight Paraffin wax “WBM-1” 190 parts by weight After heating the surfactant solution to 90 ° C., the above single amount A body solution was added, and a dispersion was prepared by mixing and dispersing for 4 hours with a mechanical disperser “CLEAMIX” (manufactured by M Technique Co., Ltd.) having a circulation path.

  A polymerization initiator aqueous solution in which 15 parts by mass of potassium persulfate (KPS) is dissolved in 211 parts by mass of ion-exchanged water is added to the dispersion, and the polymerization reaction proceeds by stirring for 2 hours at a liquid temperature of 90 ° C. Thus, “resin particle dispersion a1” was produced.

(B) Second-stage polymerization 7 parts by weight of potassium persulfate (KPS) and 184 parts by weight of ion-exchanged water are added to the “resin particle dispersion a1”, and the dispersion is heated to 80 ° C. A monomer solution containing was dropped. That is,
Styrene 415 parts by mass n-butyl acrylate 156 parts by mass n-octyl mercaptan 7.5 parts by mass After completion of dropping, the mixture was stirred at the above temperature for 2 hours to allow the polymerization reaction to proceed, and then the temperature of the liquid was 28 ° C. Cooled to. In this manner, “resin A1” made of a copolymer formed by polymerizing styrene monomer and (meth) acrylic acid monomer is formed, and “resin particle dispersion A1” is produced. did. The weight average molecular weight Mw was 20,000, and the glass transition temperature Tg was 38 ° C.

(1) -2 Preparation of “Resin Particle Dispersion A2” The amount of each compound constituting the monomer mixed solution in the second stage polymerization (b) used in the preparation of “Resin Particle Dispersion A1” is as follows: It changed as follows. That is,
Styrene 460 parts by mass n-butyl acrylate 103 parts by mass n-octyl mercaptan 7.5 parts by mass The same procedure except that the addition amount of each compound constituting each monomer mixed solution was changed as described above. Liquid A2 "was prepared. The “resin particles A2” had a weight average molecular weight Mw of 21,000 and a glass transition temperature Tg of 43 ° C.

(1) -3 Preparation of “Resin Particle Dispersion A3” The amount of each compound constituting the monomer mixed solution in the second stage polymerization (b) used in the preparation of “Resin Particle Dispersion A1” is as follows: It changed as follows. That is,
Styrene 320 parts by mass n-butyl acrylate 247 parts by mass n-octyl mercaptan 7.5 parts by mass The same procedure was followed except that the amount of each compound constituting each monomer mixed solution was changed as described above. Liquid A3 "was prepared. The “resin particles A3” had a weight average molecular weight Mw of 17,000 and a glass transition temperature Tg of 33 ° C.

(1) -4 Production of “Resin Particle Dispersion A4” (b) used in the production of “Resin Particle Dispersion A1” (b) The addition amount of each compound constituting the monomer mixed solution in the second stage polymerization is as follows: It changed as follows. That is,
Styrene 490 parts by mass n-butyl acrylate 73 parts by mass n-octyl mercaptan 7.5 parts by mass The same procedure except that the addition amount of each compound constituting each monomer mixed solution was changed as described above. Liquid A4 "was prepared. The “resin particle A4” had a weight average molecular weight Mw of 23,000 and a glass transition temperature Tg of 48 ° C.

(1) -5 Preparation of “Resin Particle Dispersion A5” The amount of each compound constituting the monomer mixed solution in the second stage polymerization (b) used in the preparation of “Resin Particle Dispersion A1” is as follows: It changed as follows. That is,
Styrene 470 parts by mass n-butyl acrylate 93 parts by mass n-octyl mercaptan 7.5 parts by mass The same procedure was followed except that the amount of each compound constituting each monomer mixed solution was changed as described above. Liquid A5 "was prepared. The “resin particle A5” had a weight average molecular weight Mw of 22,000 and a glass transition temperature Tg of 44 ° C.

(2) -1 Preparation of “Resin Particle Dispersion B1” 2 parts by mass of an anionic surfactant (sodium dodecylbenzenesulfonate: SDS) were added to a reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introducing device. A surfactant aqueous solution was prepared by dissolving in 2900 parts by mass of ion-exchanged water. While stirring the surfactant aqueous solution at a stirring speed of 230 rpm under a nitrogen stream, the temperature was raised to 80 ° C.

After 9.0 parts by weight of potassium persulfate (KPS) was added to the surfactant aqueous solution, a monomer solution composed of the following compounds was added dropwise over 3 hours. That is,
n-Butyl acrylate 198 parts by weight Methyl methacrylate 945 parts by weight Itaconic acid 60 parts by weight After completion of the dropwise addition of the monomer solution, the liquid temperature is maintained at 78 ° C. for 1 hour to advance the polymerization reaction. A “resin particle dispersion B1” containing a copolymer formed from the three polymerizable monomers was prepared. The ratio of methyl methacrylate to itaconic acid in the copolymer constituting “resin particle B1” was 83.5% by mass. The “resin particle B1” had a weight average molecular weight Mw of 280,000 and a glass transition temperature Tg of 68 ° C.

(2) -2 Production of “resin particle dispersion B2” The addition amount of each compound constituting the monomer mixed solution used in the production of “resin particle dispersion B1” was changed as follows. That is,
n-Butyl acrylate 230 parts by weight Methyl methacrylate 930 parts by weight Itaconic acid 30 parts by weight The same procedure was followed except that the amount of each compound constituting each monomer mixed solution was changed as described above. Was made. The “resin particle B2” had a weight average molecular weight Mw of 270,000 and a glass transition temperature Tg of 66 ° C.

(2) -3 Production of “Resin Particle Dispersion B3” The addition amount of each compound constituting the monomer mixed solution used in the production of “Resin Particle Dispersion B1” was changed as follows. That is,
n-Butyl acrylate 193 parts by weight Methyl methacrylate 970 parts by weight Itaconic acid 40 parts by weight The same procedure was followed except that the amount of each compound constituting each monomer mixed solution was changed as described above. Was made. The “resin particle B3” had a weight average molecular weight Mw of 320,000 and a glass transition temperature Tg of 83 ° C.

(2) -4 Production of “Resin Particle Dispersion B4” The addition amount of each compound constituting the monomer mixed solution used in the production of “Resin Particle Dispersion B1” was changed as follows. That is,
n-Butyl acrylate 250 parts by weight Methyl methacrylate 900 parts by weight Itaconic acid 37 parts by weight The same procedure was followed except that the amount of each compound constituting each monomer mixed solution was changed as described above. Was made. The “resin particle B4” had a weight average molecular weight Mw of 330,000 and a glass transition temperature Tg of 88 ° C.

(2) -5 Preparation of “Resin Particle Dispersion B5” The addition amount of each compound constituting the monomer mixed solution used in the preparation of “Resin Particle Dispersion B1” was changed as follows. That is,
n-Butyl acrylate 221 parts by weight Methyl methacrylate 945 parts by weight Itaconic acid 38 parts by weight The same procedure was followed except that the amount of each compound constituting each monomer mixed solution was changed as described above. Was made. The “resin particle B5” had a weight average molecular weight Mw of 310,000 and a glass transition temperature Tg of 85 ° C.

(2) -6 Preparation of “Resin Particle Dispersion B6” The addition amount of each compound constituting the monomer mixed solution used in the preparation of “Resin Particle Dispersion B1” was changed as follows. That is,
n-Butyl acrylate 210 parts by weight Methyl methacrylate 790 parts by weight Itaconic acid 180 parts by weight The same procedure was followed except that the amount of each compound constituting each monomer mixed solution was changed as described above. Was made. The “resin particle B6” had a weight average molecular weight Mw of 290,000 and a glass transition temperature Tg of 70 ° C.

(2) -7 Preparation of “Resin Particle Dispersion B7” The addition amount of each compound constituting the monomer mixed solution used in the preparation of “Resin Particle Dispersion B1” was changed as follows. That is,
n-Butyl acrylate 230 parts by weight Methyl methacrylate 772 parts by weight Itaconic acid 190 parts by weight The same procedure was followed except that the amount of each compound constituting each monomer mixed solution was changed as described above. Was made. The “resin particle B7” had a weight average molecular weight Mw of 290,000 and a glass transition temperature Tg of 71 ° C.

(2) -8 Preparation of “Resin Particle Dispersion B8” The addition amount of each compound constituting the monomer mixed solution used in the preparation of “Resin Particle Dispersion B1” was changed as follows. That is,
n-Butyl acrylate 220 parts by weight Methyl methacrylate 915 parts by weight Itaconic acid 30 parts by weight The same procedure was followed except that the amount of each compound constituting each monomer mixed solution was changed as described above. Was made. The “resin particle B8” had a weight average molecular weight Mw of 260,000 and a glass transition temperature Tg of 63 ° C.

(3) -1 Production of “Resin Particle Dispersion C1B1” 2 parts by mass of an anionic surfactant (sodium dodecylbenzenesulfonate: SDS) in a reaction apparatus equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introduction apparatus, And 50 mass parts (solid content conversion) of said "resin particle dispersion B1" were dissolved in 2900 mass parts of ion-exchange water, and surfactant solution was prepared. The liquid temperature was raised to 80 ° C. while stirring the surfactant solution at a rotational speed of 230 rpm under a nitrogen stream.

After adding 9.0 parts by mass of potassium persulfate (KPS) to the surfactant solution, a monomer solution composed of the following compounds was added dropwise over 3 hours. That is,
Styrene 570 parts by mass n-butyl acrylate 170 parts by mass n-octyl mercaptan 12 parts by mass After completion of the dropwise addition of the above monomer solution, the liquid temperature is maintained at 78 ° C. for 1 hour to advance the polymerization reaction. A “resin particle dispersion C1B1” containing resin particles having a structure in which “resin B1” was encapsulated in “resin C1” was produced. The “resin particles C1B1” had a weight average molecular weight of 60,000 and a glass transition temperature of 47 ° C. The content of “resin particle B1” in “resin particle C1B1” was 6.3 mass%.

  In addition, when the above-mentioned polymerization was performed to form “resin particle C1” under the condition where “resin particle B1” was not present, the weight average molecular weight Mw was 17,000 and the glass transition temperature Tg was 47 ° C.

(3) -2 Production of “resin particle dispersion C2B1” The addition amount of each compound constituting the monomer mixed solution used in the production of “resin particle dispersion C1B1” was changed as follows. That is,
Styrene 530 parts by mass n-butyl acrylate 210 parts by mass n-octyl mercaptan 12 parts by mass The same procedure was followed except that the addition amount of each compound constituting each monomer mixed solution was changed as described above to “resin particle dispersion C2B1 Was made. The “resin particles C2B1” had a weight average molecular weight Mw of 55,000 and a glass transition temperature Tg of 38 ° C. Further, the content of “resin particle B1” in “resin particle C2B1” was 6.3 mass%.

  In addition, when the above-mentioned polymerization was performed to form “resin particle C2” under the condition where “resin particle B1” was not present, the weight average molecular weight Mw was 15,000 and the glass transition temperature Tg was 37 ° C.

(3) -3 Production of “resin particle dispersion C3B3” The addition amount of each compound constituting the monomer mixed solution used in the production of “resin particle dispersion C1B1” was changed as follows. That is,
Styrene 590 parts by mass n-butyl acrylate 150 parts by mass n-octyl mercaptan 12 parts by mass The addition amount of each compound constituting each monomer mixed solution was changed as described above, and added to the surfactant solution. “Resin particle dispersion C3B3” was produced by replacing “resin particle dispersion B1” with “resin particle dispersion B3”. The “resin particles C3B3” had a weight average molecular weight Mw of 68,000 and a glass transition temperature Tg of 58 ° C. The content of “resin particle B3” in “resin particle C3B3” was 6.3 mass%.

  In addition, when the above-mentioned polymerization was performed under the condition where “resin particle B3” was not present to form “resin particle C3”, the weight average molecular weight Mw was 22,000 and the glass transition temperature Tg was 52 ° C.

(3) -4 Production of “Resin Particle Dispersion C4B2” The addition amount of each compound constituting the monomer mixed solution used in the production of “Resin Particle Dispersion C1B1” was changed as follows. That is,
Styrene 500 parts by mass n-butyl acrylate 240 parts by mass n-octyl mercaptan 12 parts by mass The addition amount of each compound constituting each monomer mixed solution was changed as described above and dissolved in a surfactant solution. “Resin particle dispersion C4B2” was produced by replacing “resin particle dispersion B1” with “resin particle dispersion B2.” The “resin particles C4B2” had a weight average molecular weight Mw of 53,000 and a glass transition temperature Tg of 35 ° C. The content of “resin particle B3” in “resin particle C4B2” was 6.3 mass%.

  In addition, when the above-mentioned polymerization was performed to form “resin particle C4” under the condition where “resin particle B2” was not present, the weight average molecular weight Mw was 13,000 and the glass transition temperature Tg was 32 ° C.

(3) -5 Preparation of “Resin Particle Dispersion C5B2” The addition amount of each compound constituting the monomer mixed solution used in the preparation of “Resin Particle Dispersion C4B2” was changed as follows. That is,
Styrene 510 parts by mass n-butyl acrylate 230 parts by mass n-octyl mercaptan 12 parts by mass The same procedure was followed except that the addition amount of each compound constituting each monomer mixed solution was changed as described above. “Resin particle dispersion C5B2 Was made. The “resin particles C5B2” had a weight average molecular weight Mw of 54,000 and a glass transition temperature Tg of 37 ° C. The content of “resin particle B2” in “resin particle C5B2” was 6.3 mass%.

  In addition, when the above-mentioned polymerization was performed to form “resin particle C5” under the condition where “resin particle B2” was not present, the weight average molecular weight Mw was 14,000 and the glass transition temperature Tg was 35 ° C.

(3) -6 Preparation of “Resin Particle Dispersion C1B2, C1B3, C1B4, C1B6, C1B7, C2B2, C2B3, C2B5, C2B8” Each monomer mixed solution used in the preparation of “resin particle dispersion C1B1” The resin resin particle dispersion B is added to the surfactant solution in a different ratio and the combination of “resin particle dispersion B” added to the surfactant solution is changed. Dispersions C1B2, C1B3, C1B4, C1B6, C1B7, C2B2, C2B3, C2B5, C2B8 ”were produced.

  The glass transition temperature (Tg) and the weight average molecular weight (Mw) of each resin particle produced as described above are summarized in Table 1 below.

(5) Preparation of “Colorant Particle Dispersion” The colorant “PIGMENT BLUE“ Dowfax 2A-1 ”” 229 is stirred while a solution obtained by dissolving 90 parts by mass of sodium dodecyl sulfate in 1600 parts by mass of ion-exchanged water is stirred. Mass parts were gradually added. Thereafter, a “colorant particle dispersion” was prepared by carrying out a dispersion treatment using a mechanical disperser “CLEARMIX”. It was 110 nm when the mass average particle diameter of the colorant particles in the prepared “colorant particle dispersion” was measured with an electrophoretic light scattering photometer “ELS-800 (manufactured by Otsuka Electronics Co., Ltd.)”.

(6) Preparation of “Toner 1” (a) Formation of core particles In a reaction vessel equipped with a stirrer, temperature sensor, and cooling pipe
"Resin particle dispersion A1" 350 parts by mass (solid content conversion)
Ion-exchanged water 1750 parts by weight “Colorant particle dispersion” 150 parts by weight were added and stirred to prepare a dispersion. A 25% aqueous sodium hydroxide solution was added to the dispersion to adjust the pH to 10.2.

  Next, 100 parts by mass of an aqueous magnesium chloride hexahydrate solution (50% by mass) was added to the stirred dispersion over 20 minutes. After the magnesium chloride hexahydrate aqueous solution was added, the temperature was raised, the temperature was raised to 80 ° C. over about 60 minutes, and the particles were aggregated and fused while being kept at 80 ° C. In this state, “Multisizer 3 (manufactured by Beckman Coulter)” is used to measure the particle size of the particles growing in the reaction vessel, and after the volume-based median diameter reaches 6.5 μm, The core particles were formed by heating and stirring at 83 ° C. for 2 hours to control the shape.

(B) Formation of shell The core particle dispersion is kept at a liquid temperature of 83 ° C.
"Resin particle dispersion C1B1" 100 parts by mass (solid content conversion)
Was added over 20 minutes. Stirring was continued for 2 hours after the addition, and “resin particles C1B1” were aggregated and fused on the surface of the core particles. Thereafter, the fusion treatment was continued for 30 minutes to form a shell.

(C) Aging, washing, drying treatment step and external additive addition step After the shell formation, 370 parts by mass of a 25% by mass sodium chloride aqueous solution was added to stop the fusion reaction, and the temperature was raised to 88 ° C. Aging treatment was performed. The particle dispersion thus formed is cooled at 4 ° C./min, then thoroughly washed with ion-exchanged water at 20 ° C., and further dried at room temperature to obtain “toner base particle 1 having a core-shell structure” Was made.

  The following “external additive” was added to the “toner base particle 1” produced, and “toner 1” was produced by performing an external addition treatment with a “Henschel mixer (Mitsui Miike Mining Co., Ltd.)”.

That is,
Silica treated with hexamethylsilazane (average primary particle size 12 nm) 0.6 parts by mass Titanium dioxide treated with n-octylsilane (average primary particle size 24 nm) 0.8 parts by mass The stirring was performed under conditions of a peripheral speed of the stirring blade of 35 m / second, a processing temperature of 35 ° C., and a processing time of 15 minutes.

1-2. Preparation of “Toner 2” Instead of “Resin Particle Dispersion C1B1” used in the preparation of “Toner 1”,
"Resin particle dispersion C1" 93.7 parts by mass (solid content conversion)
"Resin particle dispersion B1" 6.3 parts by mass (solid content conversion)
“Toner 2” was prepared in the same procedure as in the preparation of “Toner 1” except that was used.

1-3. Preparation of “Toner 3” Instead of “Resin Particle Dispersion C1B1” used in the preparation of “Toner 1”,
"Resin particle dispersion C1" 100 parts by mass (solid content conversion)
“Toner 3” was prepared in the same procedure as in the preparation of “Toner 1” except that was used.

1-4. Preparation of “Toner 4” “Toner 1” was prepared in the same manner as in “Toner 1” except that “Resin particle dispersion B1” was used instead of “Resin particle dispersion C1B1” used in the preparation of “Toner 1”. 4 "was produced.

  However, “resin particles B1” did not aggregate and fuse to the toner surface, and the target structure could not be formed. Therefore, performance evaluation was not performed.

1-5 Preparation of “Toners 5 to 21” “Resin Particle Dispersion C1B1” used in the formation of “Resin Particle Dispersion A1” shell that forms core particles in the preparation of “Toner 1” is shown in Table 2. changed. “Toners 5 to 21” were prepared in the same manner as that of “Toner 1” except that the resin particle dispersion used for forming the core and shell was changed as described above.

2. Preparation of “Developers 1 to 21” Each of the “Toners 1 to 21” was mixed with a ferrite carrier having a volume average particle diameter of 50 μm formed by coating a silicone resin, and the “Developers 1 to 21” having a toner concentration of 6%. 21 "was prepared.

3. Evaluation Experiment (1) Low Temperature Fixability As an image forming apparatus for evaluation, a copying machine “bizhub PRO C6501” (manufactured by Konica Minolta Business Technologies) was used. The fixing device used was modified so that the surface temperature of the heating roller could be changed in steps of 5 ° C. within the range of 120 to 210 ° C. Each of the toner and the developer prepared above was sequentially loaded in this image forming apparatus, and printing was performed on A4 size high-quality paper (64 g / m ² ).

Copying machine "bizhub PRO C6500" (manufactured by Konica Minolta Business Technologies Co., Ltd.) changing the fixing temperature in the range of 120 to 210 ° C in 5 ° C increments in an environment of normal temperature and humidity (20 ° C, 55% RH) Then, a solid image of 1.5 cm × 1.5 cm (attachment amount 2.0 mg / cm ² ) was taken, and the peel resistance of the image with respect to the fixing roller was visually evaluated. The temperature between the fixing temperature when the image was slightly peeled off and the lower fixing temperature at which the image was not peeled at all was defined as the fixing lower limit temperature. The lower limit fixing temperature is evaluated as follows.

A: Fixing lower limit temperature was less than 170 ° C. ○: Fixing lower limit temperature was 170 ° C. or more and less than 180 ° C. ×: Fixing lower limit temperature was 180 ° C. or more (2) Heat-resistant storability Toner 0.5 g Was placed in a 10 ml glass bottle with an inner diameter of 21 mm, the lid was closed, shaken 600 times at room temperature with a tap denser KYT-2000 (manufactured by Seishin Enterprise), and then in an environment of 55 ° C. and 35% RH with the lid removed. Left for 2 hours. Next, place the toner on a 48-mesh (mesh 350 μm) sieve, taking care not to crush the toner aggregates, set the powder tester (manufactured by Hosokawa Micron), and fix it with a press bar and knob nut. After adjusting the vibration strength to a feed width of 1 mm and applying vibration for 10 seconds, the ratio (mass%) of the amount of toner remaining on the sieve was measured.

  The toner aggregation rate is a value calculated by the following formula.

(Toner aggregation rate (%)) = (Mass of residual toner on sieve (g)) / 0.5 (g) × 100
The heat resistant storage stability of the toner was evaluated according to the criteria described below.

A: The toner aggregation rate is less than 15% by mass (the toner has excellent heat-resistant storage stability)
○: Toner aggregation rate of 20% by mass or less (good heat storage stability of toner)
X: Toner aggregation rate exceeds 20% (toner has poor heat storage stability and cannot be used)

  As is apparent from Table 3, Examples 1-21 in the present invention are good in all characteristics, but Comparative Examples 1-3 outside the present invention have problems in at least any of the characteristics. Recognize.

DESCRIPTION OF SYMBOLS 1 Toner particle 2 Shell layer 3 Core particle | grains of seed polymerization 4 Core part (core particle)
1Y, 1M, 1C, 1K Photoconductor 4Y, 4M, 4C, 4K Developing device 5Y, 5M, 5C, 5K, 5A Transfer roll 6Y, 6M, 6C, 6K Cleaning device 7 Intermediate transfer body unit 24 Heat roll type fixing device 70 Intermediate transfer member 71 Heating roller 72 Pressure roller 75 Heating member 81 Heating roller 82 Heating roller coating layer 83 Pressure roller core metal 84 Pressure roller coating layer

Claims (4)

  A core-shell structured toner for developing electrostatic images having a core layer containing at least a binder resin and a release agent, and a shell layer, wherein the resin layer forming the shell layer is a main binder resin of the shell layer. Is a toner for developing an electrostatic charge image, wherein the toner is formed from a latex produced by seed polymerization using fine resin particles having different compositions as nuclei. When the glass transition temperature of the binder resin forming the shell layer is Tg1, the glass transition temperature of the resin forming the resin fine particles contained in the shell layer is Tg2, and the glass transition temperature of the core forming resin is Tg3,
35 ≦ Tg1 ≦ 50
65 ≦ Tg2 ≦ 85
20 ≦ (Tg2−Tg1) ≦ 45
35 ≦ Tg3 ≦ 45
(However, all temperature units are expressed in ° C)
The toner for developing an electrostatic charge image according to claim 1, wherein: When the solubility parameter of the binder resin forming the shell layer is SP1, the SP value of the resin forming the resin fine particles contained in the shell layer is SP2, and the SP value of the core-forming resin is SP3, SPx and SPy If the difference between the values is Δx, y,
0.2 ≦ Δ1, 2 ≦ 1.0
0 ≦ Δ1, 3 ≦ 0.1
(However, the unit of the value is (cal / cm ³ ) ^1/2 )
The toner for developing an electrostatic charge image according to claim 1, wherein:   4. The electrostatic charge image developing toner according to claim 1 is charged by stirring, an unfixed toner image formed by developing an electrostatic latent image is transferred to an image support, and then heated and fixed. An image forming method.

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