JP4189601B2 - Toner, toner manufacturing method, and image forming method - Google Patents

Description

  The present invention relates to a toner, a method for producing the toner, and an image forming method using the toner.

  The field of image forming technology based on electrophotography such as copying machines and printers is rapidly spreading with the progress of digitization technology, and the number of used devices has been greatly increased.

In general, recent developments in electrophotographic technology are concentrated in the following four points, and energetic research and development are underway.
(1) Making the image forming apparatus compact (2) Speeding up the image forming apparatus (3) Realizing high-quality color image formation (4) Reducing power consumption during operation (saving) Electricity)
Here, in order to solve the above problems (1) to (3), even when image formation is performed by rotating a small-diameter developing roller at high speed, image contamination due to toner scattering or deterioration of the developing roller due to toner fusion is achieved. There is a difficulty that it is necessary not to generate such a problem. In response to these problems, a technique has been disclosed in which toner particles with uniform chargeability are designed to increase the charging speed of the toner and to increase the charge retention capability (see, for example, Patent Document 1).

  In (4) power saving, the use of printers in offices due to the progress of the network environment and the use of digital devices such as printers and facsimiles in homes are becoming popular in offices and homes. With the expansion of usage, reducing fixed power and power costs has become an unavoidable issue.

  In addition, the expansion of electrophotographic image forming technology to a new field requires that there is no need to create plates as in the case of printing in the electrophotographic method, and printing can be performed at a high speed as many documents as necessary when needed. Expansion into on-demand (POD) and book-on-demand (BOD) areas is expected.

  However, although the current image forming technology is excellent in speed, the usable paper types are limited, and image formation cannot be performed on every paper. For example, in the case of thin paper, wrinkles are likely to occur, and in general coated glossy paper, there has been a problem of occurrence of image defects (blisters) due to water vapor ejection. In addition, it has been difficult to develop color reproducibility so that a beautiful color image can be formed without being affected by the collation accuracy at the time of bookbinding and the paper type.

  In order to achieve these problems, a chemical toner typified by polymerized toner has attracted attention as in Patent Document 1 described above, and it is possible to design a toner that dynamically controls the toner particle structure to solve these problems. Has been tried. For example, it is possible to suppress the exposure of the colorant to the toner particle surface by fusing another resin particle to the resin particle surface containing the resin and the colorant to form a resin layer and modifying the surface of the toner particle. The toner technology that enables stable image formation in a high humidity environment, and the dispersion state and occupation state of toner-containing components are controlled by the manufacturing process to form particles, which are affected by environmental factors such as temperature and humidity. Although the technique of the toner which made it difficult was mentioned, it was not enough yet (for example, refer patent document 2, 3 and 4).

In particular, a technique for improving the toner performance by coating the surface of the toner particles with a resin has been proposed, but the improvement of the aggregation resistance during storage and transportation has not been sufficient. Further, it has been insufficient to maintain a stable charging speed and charge retention over a long period of time.
JP 2004-54240 A JP 2002-116574 A JP 2002-351142 A JP-A-10-26842

  The present invention has been made in view of the above problems, and relates to a toner used as an electrophotographic image forming apparatus such as a small-sized, high-speed output copying machine, printer, or facsimile, and aims to solve the following problems. Is.

  That is, the present invention remarkably improves the charging speed and the charge holding ability, outputs a good and stable toner image even when the developing device is downsized, and enables the toner image to be fixed to the transfer material at a low temperature. Another object of the present invention is to provide a toner having excellent agglomeration resistance in which toner particles do not agglomerate even if the toner is stored or transported without being kept cold or insulated.

  Further, the present invention provides a toner capable of forming a beautifully finished image having sufficient fixing strength and uniform glossiness even when the toner image is fixed at a low fixing temperature. The purpose is to do.

  Another object of the present invention is to provide a toner capable of forming a stable image on a paper type, such as glossy coated paper or cardboard, for which toner image formation was very difficult with the prior art. is there. In other words, by expanding the selection range of paper types on which toner images can be formed, there is no need to bother to generate plates, and a print-on-demand image forming technology that can print only the required number of copies. An object is to provide a toner that can be developed.

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

(1)
Consists of toner particles containing a resin and a colorant,
When the toner particles were cut into 100 nm sections and observed with a transmission electron microscope with an acceleration voltage of 80 kV,
The toner particles include a region A containing a colorant, and an alkyl group or alkylene group having 6 to 20 carbon atoms that can transmit electrons to the region within 1 μm from the surface of the toner particles. And a region B containing a vinyl polymer having a toner.

(2)
The solubility parameter value of the resin contained in the region A and the region B is lower in the region B than in the region A, and the difference is 0.20 to 0.70. Toner.

( 3 )
The region B is made of a resin having a glass transition temperature of 50 to 65 ° C., and the region A is made of a resin containing a fixing aid and having a glass transition temperature of −20 to 39 ° C. The toner according to 1 ) .

( 4 )
A toner production method for producing toner particles through a step of forming another region B around a region A containing a colorant,
The solubility parameter value of the resin contained in the region A and the region B is that the region B is lower than the region A, and the difference is 0.20 to 0.70.
The resin for forming the region B is formed using a polymerizable monomer having an alkyl group or alkylene group having 6 to 20 carbon atoms which may be branched.

( 5 )
An image forming method using the toner described in (1) or (2) above, wherein the surface temperature of the transfer material is heated to 80 to 105 ° C. to fix the toner image on the transfer material. Image forming method.

  According to the present invention, the charging speed and the charge retention ability are remarkably improved, a good and stable toner image can be output even if the developing device is downsized, and the toner image can be fixed on the transfer material at a low temperature. It is possible to provide a toner having excellent anti-agglomeration properties in which toner particles do not agglomerate even when stored or transported without being cooled or insulated.

  That is, the toner obtained in the present invention has a charging speed that can be applied to a high-speed developing process as performed in a small developing device having a developing roller diameter of 10 mm or less, and has a low-temperature fixability at the time of fixing. It is possible to achieve both cohesion resistance during storage.

  In addition, the melting during heat fixing proceeds, the color reproduction region is expanded, and the occurrence of filming (fusion) on the surface of the photoreceptor, the surface of the developing roller, and the surface of the member that contacts the melted toner is suppressed.

  Furthermore, even when image formation is performed on thin paper, fixing wrinkles do not occur, and when image formation is performed on coated paper or cardboard, uniform glossiness and an evenly beautiful print can be obtained. It became possible to expand the range of usable paper types.

  The toner according to the present invention has a region in which toner particles are relatively easily transmitted at the outer edge of the toner particle when the toner particle is cut into 100 nm sections and observed with an accelerating voltage of 80 kV with a transmission electron microscope. What is observed.

  The inventors of the present invention improve the charging speed and charge holding performance of the toner by using a structure in which a resin having a property of easily transmitting electrons is present in the outer edge portion of the toner particle, that is, a region near the surface of the toner particle. At the same time, it has been found that a toner capable of achieving both good fixing performance at low temperature and improvement in anti-aggregation property during storage can be obtained.

  In the present invention, the region close to the surface of the toner particles has a region that easily transmits electrons, but this agglomerates resin fine particles that easily transmit electrons around the resin particles containing the colorant. Thus, this region is formed.

  Hereinafter, the toner particles according to the present invention will be described in detail.

[Structure of toner particles according to the present invention]
First, the structure of the toner particles according to the present invention will be specifically described.

  FIG. 1 is a schematic diagram showing the structure of toner particles according to the present invention.

  In FIG. 1, T is toner particles, A is a region containing a colorant, B is a region relatively easy to transmit electrons as compared to the region A, 1 is a colorant, and 2 is a release agent.

  The toner according to the present invention forms the region B by aggregating and covering the surface of the resin particles forming the region A with resin particles having a composition different from that of the region A in the manufacturing process of the toner particles T. is there.

  The toner particles according to the present invention have a region B in a region within 1 μm from the toner particle surface. As shown in FIG. 1- (a), the thickness of the region B is preferably 1 μm or less, more preferably 0.08 to 1.00 μm, and further preferably 0.12 to 0.40 μm. However, even if a part of the region B enters the inside of the region A as shown in FIG.

  Further, it has been confirmed that the region B does not necessarily completely cover the toner particle surface, but if the region B exists in a region within 1 μm from the toner particle surface, the problem of the present invention is solved. By coating 40 to 100%, preferably 50 to 95%, it is possible to achieve both low-temperature fixability and anti-aggregation property during storage.

  It has been confirmed that the toner according to the present invention has stable charge retention performance. As described above, it is not clear why the stable charge retention performance is manifested. However, the toner according to the present invention is probably between the region A and the region B after the charge density on the toner particle surface reaches a certain level. It is presumed that the charge can move so that a constant level of charge can always be held on the toner particle surface. That is, in the toner according to the present invention, when the charge is generated and the charge density on the surface of the toner particle reaches a certain level, the charge moves to the region A and the charge is presumed to be held in the whole toner particle. . Then, since the charge moved to the region A can move to the region B, it is presumed that even if the charge density on the toner particle surface decreases, the charge immediately moves to the region B and maintains the charge density on the toner particle surface. The

  On the other hand, in the conventional toner, the charge is only accumulated on the outermost surface of the toner particle, and the charge does not move into the particle. And even if the charge density on the surface of the toner particles is lowered, it is presumed that the charge retention performance is reduced because it does not have enough charge to compensate for it.

  The reason why the toner according to the present invention can achieve both the low temperature fixing property and the anti-aggregation property during storage is not clear, but the region A and the region B are probably non-phase at the molecular level. Even if the region A inside the toner particles is made of a resin having a low softening temperature and a low glass transition temperature, the resin constituting the region B has a lower glass transition temperature due to the resin constituting the region A. It is presumed that no phenomenon such as plasticization occurs. As a result, it is presumed that the toner according to the present invention can achieve both of the low temperature fixing property and the aggregation resistance.

[Toner structure detection means]
In the present invention, it is found that the toner particles are contrasted by observing the toner particles with a transmission electron microscope in which the toner particles have a section of 100 nm and the acceleration voltage is 80 kV. The present inventors have found that it is a reflection of the constituent resin composition. That is, in the present invention, it was found that the resin composition (monomer composition) of the toner particles can be quantified when the toner particles are cut into 100 nm sections and observed with a transmission electron microscope at an acceleration voltage of 80 kV.

  In conventional transmission electron microscope observation, that is, when the acceleration voltage is set to around 200 kV, it was possible to observe the state of the colorant and the release agent in the toner particles, but the resin composition constituting the toner particles Could not be observed. As described above, the present invention finds conditions under which the resin composition of toner particles can be observed with a transmission electron microscope.

  The toner particles according to the present invention have a structure having a region B containing a resin having a property of relatively easily transmitting an electron beam on the surface of the region A as described above. The fact that the toner particles according to the present invention have a structure having the region B around the region A is observed by a transmission electron microscope (TEM) of a toner particle section stained with ruthenium tetroxide or the like.

  The structure of the toner particles is sufficiently observed with a transmission electron microscope (TEM) well known among those skilled in the art. For example, “H-9000NAR” (manufactured by Hitachi, Ltd.), “JEM-200FX” (JEOL Ltd.) Manufactured) and the like. In the present invention, the size of the region A and the region B in the toner particle can be calculated from the result of the transmission electron micrograph from the projection surface of 10 or more toner particles at a magnification of 10,000 times. Note that the magnification of observation can be adjusted within a range in which the sectional structure of one toner particle is known.

  The observation method using a transmission electron microscope is performed by a normal method used when measuring toner particles. For example, the procedure is as follows. First, an observation sample is prepared. After sufficiently dispersing toner particles in a room temperature curable epoxy resin, the toner particles are embedded and cured to produce a block. The produced block is dyed by using ruthenium tetroxide or osmium tetroxide in combination as necessary. Then, using a microtome equipped with diamond teeth, the thickness is set to 100 nm and cut into a thin piece to prepare a measurement sample.

  Next, a photograph of the cross-sectional shape of the toner particles is taken using a transmission electron microscope (TEM). The resin composition in the toner particles is visually confirmed from the photograph. If necessary, it is also possible to arithmetically process image information photographed by an image processing apparatus “Luzex F” (manufactured by Nireco) to increase the layer thickness in the toner particles.

[Means for Realizing Toner According to the Present Invention]
Next, means for realizing the toner according to the present invention will be described.

The toner according to the present invention having a region where electrons can be relatively easily transmitted to the outer edge of the toner particle when observed with an accelerating voltage of 80 kV with a transmission electron microscope is realized by satisfying the following conditions. is there. That is,
(A) The solubility parameter value (SP value) of the resin contained in the region A and the region B is that the region B is lower than the region A, and the difference is 0.20 to 0.70.
(B) The resin contained in the region B has a vinyl polymer having an alkyl group or alkylene group having 6 to 20 carbon atoms which may be branched.
(C) Region B is made of a resin having a glass transition temperature (Tg) of 50 to 65 ° C., and Region A is made of a resin containing a fixing aid and having a glass transition temperature of −20 to 39 ° C.

  Hereinafter, these will be described.

[Solubility parameter value]
In the present invention, the resin forming the region B in the toner particles is not compatible with the resin in the region A, and the resin forming the region B has sufficient adhesiveness with the region A.

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

The solubility parameter value (SP value) is a numerical value representing the magnitude of the cohesive energy of a substance. According to the method proposed by Feors “Polym. Eng. Sci., Vol14, p147 (1974)”, evaporation of atoms or atomic groups is performed. When the energy and the molar volume are Δe _I and Δv _i , respectively, the solubility parameter value σ of the binder resin is calculated by the following formula (1).

Formula (1)
σ = (ΣΔe _i / ΣΔv _i ) ^1/2
The solubility parameter value of each vinyl copolymer is calculated from 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 and y / My. 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 (2).

Formula (2)
SP = {(x * SPx / Mx) + (y * SPy / My)} * 1 / C
The solubility parameters SPx and SPy of each monomer are calculated by the above formula (1), and specific values are described in documents such as Polymer Handbook (published by Wiley) 4th edition. Use what you have.

  The solubility parameter value can be controlled by changing the composition ratio of monomers constituting the vinyl copolymer. For example, a copolymer resin formed using styrene and methyl methacrylate is used. Thus, it has been confirmed that the solubility parameter value tends to decrease by decreasing the composition ratio of styrene and increasing the composition ratio of methyl methacrylate.

  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 “PolyInfo” (http://polymer.nims.go.jp) provided by the National Institute for Materials Science //Polymer.nims.go.jp/guide/guide/p5110.html).

  The solubility parameter value (SP value) of the monomer is determined as follows.

When calculating the solubility parameter value (SP value) of a certain monomer A, “Polym. Eng. Sci. Vol14. P114” proposed by Fedors for atoms or atomic groups in the molecular structure of the monomer. (1974) ”, the evaporation energy (Δ _ei ) and the molar volume (Δ _vi ) are obtained and calculated from the above formula (1).

  However, for a double bond that is cleaved during polymerization, the cleaved state is the molecular structure.

  The solubility parameter value of each monomer below is the value obtained by the above calculation method.

Styrene 10.55
Butyl acrylate 9.77
2-Ethylhexyl methacrylate 9.04
Methyl methacrylate 9.93
Methacrylic acid 12.54
Acrylic acid 14.04
Using this value, the solubility parameter value of the copolymer is determined according to the above equation (2).

  Further, when the resin constituting the region A is multistage polymerization, the solubility parameter of the final stage copolymer resin is set as the solubility parameter value of the region A.

  In the present invention, as described above, the solubility parameter values of the resins contained in the regions A and B are stable when the region B is lower than the region A and the difference is 0.20 to 0.70. Compatibility is expressed, and 0.30 to 0.60 is more preferable.

  In the toner according to the present invention, the SP value of the copolymer resin forming the region A is preferably 10.10 to 11.00, more preferably 10.20 to 10.70. The SP value of the copolymer resin can be controlled by appropriately selecting the type of polymerizable monomer forming the copolymer and its ratio.

  As described above, in the toner according to the present invention, the resin forming the region B and the region A has a difference that the solubility parameter value (SP value) of the both has a certain degree, so that there is a non-phase between the region A and the region B. It expresses solubility.

  In the toner according to the present invention, when the difference between the SP value in the region A and the SP value in the region B is 0.20 to 0.70, good adhesion is exhibited between the two. The method for ensuring good adhesion to the surface of the region A is, for example, selecting the type of the polymerizable monomer of the resin constituting the region B and the resin constituting the region A from the exemplary compounds described later, and the SP value of both This is possible by setting the difference within the above range. However, the exemplary compounds are shown for clarifying the achievement means, and are not limited thereto.

[Resin forming region B]
In the present invention, in order to make the region B at the outer edge of the toner particle relatively easy to transmit electrons, a vinyl polymer having an alkyl group or alkylene group having 6 to 20 carbon atoms which may be branched is used. It is preferable to form the region B. The resin is produced by polymerizing a monomer having an alkyl group or alkylene group having 6 to 20 carbon atoms which may be branched.

  Examples of the polymerizable monomer containing an alkyl group or alkylene group having 6 to 20 carbon atoms may include hexyl (meth) acrylate, 2-ethylhexyl methacrylate, hexamethylene glycol diacrylate, and behenyl. Examples thereof include diacrylate of glycol, and among them, 2-ethylhexyl methacrylate is particularly preferable.

  As for the copolymer ratio of the said polymerizable monomer in the copolymer resin which forms the area | region B, 8-40 mass% is preferable.

  Moreover, it is also preferable to copolymerize the monomer which produces resin which forms the area | region B with the polymerizable monomer which raises the glass transition temperature (Tg) of resin, such as methyl methacrylate, styrene, and methacrylic acid.

  In addition to the above, these polymerizable monomers may have a form of an acid anhydride or a vinyl carboxylic acid metal salt.

  Moreover, in this invention, you may form copolymer resin which forms the area | region B using a styrene-type monomer together.

〔Glass-transition temperature〕
In order to produce the toner according to the present invention, the glass transition temperature of the resin contained in the region B is 50 to 65 ° C., and the glass transition temperature of the resin contained in the region A is −20 to 39 ° C. It is preferable.

  The glass transition temperature is typically measured by a differential calorimetric analyzer (DSC). Specific examples of the measuring apparatus include DSC-7 manufactured by Perkin Elmer.

  A specific method for measuring the glass transition temperature is, for example, as a temperature raising / cooling condition, after standing at −30 ° C. for 1 minute, the temperature is raised to 100 ° C. under a condition of 10 ° C./min (first temperature raising process). Then, after standing at 100 ° C. for 1 minute, it is cooled to 0 ° C. under the condition of 10 ° C./min (first cooling process). This operation deletes the previous history. Next, after standing at 0 ° C. for 1 minute, the temperature is raised to 100 ° C. under a condition of 10 ° C./min (second temperature raising process). And the method of calculating | requiring the endothermic peak temperature of 2nd heat (2nd temperature increase) and making it Tg is mentioned.

  The glass transition temperature Tg is determined by measuring the baseline extension below the glass transition point of the DSC thermogram in the glass transition region and the tangent line indicating the maximum slope from the peak rise to the peak apex. The temperature of the intersection point is defined as the glass transition temperature.

  The glass transition temperature can also be measured using an atomic force microscope. That is, the temperature at which the stage of the atomic force microscope is heated to 0 to 60 ° C. and the hardness of the toner slice or block changes may be set as the glass transition temperature Tg.

  Furthermore, as a method for calculating the glass transition temperature, the following theoretical glass transition temperature may be calculated in the present invention. Here, 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. It is.

  That is, the theoretical glass transition temperature Tg (referred to as absolute temperature Tg ′) is calculated from the following formula (3) using the glass transition temperature of the homopolymer of the component constituting the copolymer resin.

Formula (3)
1 / Tg ′ = W ₁ / T ₁ + W ₂ / T ₂ +... + W _n / T _n
(Wherein W ₁ , W ₂ ,... W _n are the mass fractions of the respective polymerizable monomers with respect to the total polymerizable monomers used in the production of the copolymer resin, T ₁ , T _2. · · T _n denotes the glass transition temperature (absolute temperature) of a homopolymer formed using the polymerizable monomer.)
In the toner according to the present invention, there may be some difference in the theoretical glass transition temperature value, the measurement result obtained with the differential calorimeter, or the result with the atomic force microscope. It does not deny the technical idea of the invention or affect the results.

  The glass transition temperature of the copolymer resin can be controlled by the type and ratio of the polymerizable monomer that forms the copolymer.

  In the toner according to the present invention, in addition to the above-described factors, it is more preferable to set the molecular weight and the softening point temperature of the resin forming the regions B and A as described below.

[Molecular weight]
In producing the toner according to the present invention, it is preferable to set the molecular weight of the resin forming the region B and the region A in the toner particles to a specific range, respectively. Specifically, the molecular weight of the resin constituting the region A is 15,000 to 25,000, the molecular weight of the resin constituting the region B is in the range of 10,000 to 35,000, and the molecular weight is set so as to have a peak molecular weight. It is preferable to set.

  The resin constituting the region A and the region B is formed from a plurality of types of vinyl copolymer resins, but the resin constituting the region B has a peak in the above range in order to maintain the strength of the toner particles. It preferably has a molecular weight.

  The peak molecular weight can be measured by a gel permeation chromatography (GPC) method using tetrahydrofuran (THF) as a column solvent.

  Specifically, 1 ml of THF is added to 1 mg of a measurement sample, and the mixture is sufficiently dissolved by stirring using a magnetic stirrer at room temperature. Subsequently, after processing with a membrane filter having a pore size of 0.45 to 0.50 μm, the solution is injected into GPC. The measurement conditions of GPC are measured by stabilizing the column at 40 ° C., flowing THF at a flow rate of 1 ml / min, and injecting about 100 μl of a sample having a concentration of 1 mg / ml. As the column, it is preferable to use a combination of commercially available polystyrene gel columns. For example, Shodex GPC KF-801, 802, 803, 804, 805, 806, 807 made by Showa Denko KK, TSKgel G1000H, G2000H, G3000H, G4000H, G5000H, G6000H, G7000H, TSK guard column manufactured by Tosoh Corporation Combinations can be mentioned.

  As the detector, a refractive index detector (IR detector) or a UV detector is preferably used. In measuring the molecular weight of a sample, the molecular weight distribution of the sample is calculated using a calibration curve created using monodisperse polystyrene standard particles. About 10 points are preferably used as polystyrene for preparing a calibration curve.

[Softening temperature]
The softening point (Tsp) of the toner according to the present invention is preferably 75 to 98 ° C., and can be fixed even when the temperature of the transfer material surface is 100 ° C. or less. This is because, in the toner according to the present invention, the ratio of the region B is 5 to 30% on a mass basis with respect to the toner particles, so that the toner storage stability can be improved without affecting the softening point. ing. Therefore, the toner according to the present invention enables fixing at a temperature at which image defects due to generation of water vapor and deformation (curl) of the transfer material do not occur.

  The softening point of the toner particles can be controlled by, for example, controlling the type of monomer constituting the resin used to form the resin particles or the monomer composition ratio of the copolymer, or controlling the amount of the chain transfer agent. Thus, a method for controlling the degree of polymerization, a method for adjusting the type and amount of the fixing aid such as a release agent added to the toner, and the like can be used. By combining these, a toner having a target softening point can be obtained. . As an example, there may be mentioned a method of controlling the softening point by plotting the relationship between the molecular weight and the softening point in a specific resin.

As a method for measuring the softening point of the toner, for example, a flow tester CFT-500 (manufactured by Shimadzu Corporation) is used, and the sample is preliminarily set to 9.2 mesh pass (mesh opening 2.0 mm), 32 mesh on (mesh opening). 0.5 mm), then formed into a cylindrical shape with a height of 10 mm, applied with a load of 20 kg / cm ² from the plunger while heating at a heating rate of 6 ° C./min, 1 mm in diameter, 1 mm in length The nozzle is pushed out, thereby drawing a curve (softening flow curve) between the plunger drop amount and temperature of the flow tester, and the temperature corresponding to the drop amount of 5 mm is taken as the softening point.

[Resin used in region A]
Next, a resin (that is, a polymer) that is preferably used in the region A will be described.

  As the polymerizable monomer of the resin constituting the region A, a resin formed by using a styrene monomer or a monomer mixture obtained by mixing a styrene monomer and another copolymerizable monomer is preferable. The amount of the styrene monomer is preferably 50% by mass or more based on the total amount of the monomers.

  Examples of the styrene monomer include styrene and p-methylstyrene. Other copolymerizable monomers used together with the styrene monomer include acrylic acid ester monomers such as ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate; methyl methacrylate, methacryl Methacrylic acid ester monomers such as ethyl acetate and butyl methacrylate; Alkyl vinyl ethers such as methyl vinyl ether; Vinyl ester monomers such as vinyl acetate and vinyl butyrate; N-methyl acrylamide and N-ethyl acrylamide Examples thereof include alkyl-substituted acrylamides; nitrile monomers such as acrylonitrile and methacrylonitrile; polyfunctional monomers such as divinylbenzene, ethylene glycol (meth) acrylate, and trimethylolpropane tri (meth) acrylate.

  Examples of the crosslinkable monomer include those having two or more unsaturated bonds such as divinylbenzene, divinylnaphthalene, divinyl ether, diethylene glycol methacrylate, ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, and diallyl phthalate.

  In this way, by using a crosslinkable monomer, it becomes difficult to give regularity and synchronism to the structure of the polymer chain constituting the binder resin, so it becomes easier to obtain an amorphous resin. It is possible to improve the strength of the resin without significantly increasing the binding energy between the polymer chains. As a result, fixing at a low temperature is possible and, for example, the durability of the toner can be improved without breaking the toner even if stirring in the developing device is repeated.

[Method for Producing Toner Particles According to the Present Invention]
Next, a toner manufacturing method according to the present invention will be described.

  A preferable method for producing the toner according to the present invention is an emulsion polymerization method in which it is easy to give an appropriate thickness unevenness to the film thickness of the region B covering the region A. When the region B has an appropriate film thickness unevenness, it is preferable for developing fixability at a low temperature and securing anti-aggregation characteristics during storage.

  Production of resin particles (a) forming region A, region A particles, particle dispersion of region A, resin particles (b) forming region B, dispersion of resin particles forming region B, and toner particles The process will be described.

(Resin particles forming region A (a))
As described above, the resin particles (a) forming the region A have the kinds of polymerizable monomers and the blending ratio thereof so that the SP value is 10.10 to 11.00 and the Tg is -20 to 39 ° C. It is selected and copolymerized so as to have a molecular weight of 15,000 to 25,000. The number average primary particle diameter of the resin particles (a) is preferably 10 to 1000 nm.

  The SP value and Tg of the region A are the same as the SP value and Tg of the resin particles (a) forming the region A.

  The region A particles are obtained by polymerizing at least a polymerizable monomer in an aqueous medium. In this production method, resin particles (a) are obtained by polymerizing a polymerizable monomer by a suspension polymerization method. Or emulsion polymerization of a monomer in a liquid (in an aqueous medium) to which an emulsion of a necessary additive is added, or miniemulsion polymerization to prepare fine resin particles (a), It is preferable to produce the resin particles by adding the charge controllable resin particles as necessary, and then adding an aggregating agent such as an organic solvent or salts to agglomerate and fuse the resin particles.

<Suspension polymerization method>
As an example of the method for producing the region A particles, the charge controllable resin is dissolved in the polymerizable monomer, and various components such as a colorant and, if necessary, a fixing aid, a release agent, and a polymerization initiator are used. The material is added, and various constituent materials are dissolved or dispersed in the polymerizable monomer using a homogenizer, a sand mill, a sand grinder, an ultrasonic disperser, or the like. The polymerizable monomer in which the various constituent materials are dissolved or dispersed is dispersed in oil droplets having a desired size as the region A particles in an aqueous medium containing a dispersion stabilizer using a homomixer or a homogenizer. Thereafter, the stirring mechanism is transferred to a reaction device (stirring device) which is a stirring blade described later, and the polymerization reaction is advanced by heating to form region A particles.

<Emulsion polymerization method>
Further, as a method for producing the region A particles, a method in which the resin particles (a) are prepared by salting out / fusion in an aqueous medium can also be mentioned. The method is not particularly limited, and examples thereof include methods disclosed in JP-A-5-265252, JP-A-6-329947, and JP-A-9-15904. That is, a method of salting out, agglomerating, and fusing a plurality of fine particles composed of resin particles and colorants, and optionally dispersed particles of constituent materials such as fixing aids and release agents, or resins and colorants. In particular, after dispersing these in water using an emulsifier, a coagulant with a critical coagulation concentration or higher is added for salting out, and at the same time, heat fusion is performed at or above the glass transition temperature of the formed polymer itself. Gradually grow the particle size while forming particles, stop the particle size growth by adding a large amount of water when the target particle size is reached, further control the shape by smoothing the particle surface while heating and stirring Thus, region A particles can be formed. Here, a solvent that is infinitely soluble in water, such as alcohol, may be added simultaneously with the flocculant.

  In the method for producing the region A particles, at least the polymerizable monomer is dissolved, and then the resin particles (a) formed through the step of polymerizing the polymerizable monomer and the colorant particles are salted out / fused. Is obtained.

  In addition, the method for producing the region A particles is to salt out / fuse the resin particles (a) obtained by the multistage polymerization method and the colorant particles. The multistage polymerization method will be described below.

<< Method for Producing Resin Particles (a) Obtained by Multistage Polymerization Method >>
The manufacturing method of area | region A particle | grains is comprised from the process shown below.

1: Multi-stage polymerization step 2: Salting out / fusion process for obtaining region A particles by salting out / fusion of resin particles (a) and colorant particles Hereinafter, each step will be described in detail.

[Multistage polymerization process]
The multi-stage polymerization step is a polymerization method performed to expand the molecular weight distribution of the resin particles so as to obtain region A particles in which the occurrence of offset is prevented. That is, in order to form phases having different molecular weight distribution in one resin particle, the polymerization reaction is performed in multiple stages, and the obtained resin particle has a molecular weight gradient from the center of the particle toward the surface layer. It is intended to be formed. For example, a method of forming a low molecular weight surface layer by first obtaining a high molecular weight resin particle dispersion and then newly adding a polymerizable monomer and a chain transfer agent is employed.

  Hereinafter, a two-stage polymerization method and a three-stage polymerization method, which are representative examples of the multistage polymerization method, will be described.

<Two-stage polymerization method>
The two-stage polymerization method is a method for producing resin particles (a) composed of a central portion (core) formed from a high molecular weight resin and an outer layer (shell) formed from a low molecular weight resin.

  This method will be described in detail. First, a monomer solution of a monomer is prepared, and the monomer solution is dispersed in oil droplets in an aqueous medium (for example, a surfactant aqueous solution). Is polymerized (first stage polymerization) to prepare a dispersion of high molecular weight resin particles.

  Next, a polymerization initiator and a monomer for obtaining a low molecular weight resin are added to the dispersion of the resin particles, and the monomer is polymerized in the presence of the resin particles (second-stage polymerization). Thus, a coating layer made of a low molecular weight resin (monomer polymer) is formed on the surface of the resin particles.

<Three-stage polymerization method>
The three-stage polymerization method is a method for producing resin particles (a) composed of a central portion (core) formed from a high molecular weight resin, an intermediate layer, and an outer layer (shell) formed from a low molecular weight resin. The region A particles exist as the resin particles (a) as described above.

  This method will be specifically described. First, a dispersion of resin particles obtained by a polymerization process (first-stage polymerization) according to a conventional method is added to an aqueous medium (for example, an aqueous solution of a surfactant). In the aqueous medium, the monomer solution of the monomer is dispersed in oil droplets, and then this system is polymerized (second-stage polymerization) to form resin (core particles) on the surface of the resin particles (core particles). A coating layer (intermediate layer) made of a monomer polymer) is formed to prepare a dispersion of composite resin particles (high molecular weight resin-intermediate molecular weight resin).

  Next, a polymerization initiator and a monomer for obtaining a low molecular weight resin are added to the obtained dispersion of composite resin particles, and the monomer is polymerized in the presence of the composite resin particles (third-stage polymerization). ), A coating layer made of a low molecular weight resin (monomer polymer) is formed on the surface of the composite resin particles.

  One feature of the method for producing the region A particles is that the polymerizable monomer is polymerized in an aqueous medium. That is, when forming a coating layer (intermediate layer), a monomer solution is dispersed in oil droplets in an aqueous medium, and a polymerization initiator is added to this system to perform polymerization treatment, thereby obtaining latex particles. is there.

  As a suitable polymerization method for forming the resin particles or the coating layer, a monomer solution is dissolved in an aqueous medium obtained by dissolving a surfactant having a concentration lower than the critical micelle concentration by utilizing mechanical energy. A method of preparing a dispersion by dispersing oil droplets, adding a water-soluble polymerization initiator to the obtained dispersion, and performing radical polymerization in the oil droplets (hereinafter referred to as “mini-emulsion method” in the present invention). Can be mentioned. In the above method, an oil-soluble polymerization initiator may be used instead of or together with the water-soluble polymerization initiator.

  Here, the disperser for dispersing oil droplets by mechanical energy is not particularly limited. For example, a stirring device “CLEARMIX” (M technique (M Co., Ltd.), ultrasonic disperser, mechanical homogenizer, manton gorin, pressure homogenizer, and the like. The dispersed particle diameter is 10 to 1000 nm, preferably 50 to 1000 nm, and more preferably 30 to 300 nm.

  In addition, as another polymerization method for forming the resin particles or the coating layer, a known method such as an emulsion polymerization method, a suspension polymerization method, or a seed polymerization method may be employed.

  The particle diameter of the resin particles (a) obtained in this polymerization step is in the range of 10 to 1000 nm as a mass average particle diameter measured using an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.). Preferably there is.

  The glass transition temperature (Tg) of the resin particles (a) is preferably in the range of -20 to 39 ° C, more preferably 10 to 37 ° C.

  The region A particles are obtained by forming a resin layer obtained by fusing the resin particles (a) by the salting-out / fusing method, and this will be described below.

[Salting out / fusion process]
This salting-out / fusion process is performed by salting out / fusion-bonding the resin particles (a) and the colorant particles obtained in the multistage polymerization process (to cause salting-out and fusion simultaneously). This is a step of obtaining A particles.

  In the present invention, salting out / fusion means that salting out (aggregation of particles) and fusion (disappearance of the interface between particles) occur simultaneously, or act of causing salting out and fusion at the same time. . In order to perform salting-out and fusion at the same time, particles (resin particles (a) and colorant particles) are aggregated under a temperature condition equal to or higher than the glass transition temperature (Tg) of the resin constituting the resin particles (a). It is necessary to let

  In this salting-out / fusion process, the resin particles (a) and the colorant particles are salted out / fused together with internal additive particles such as charge control agents (fine particles having a number average primary particle size of about 10 to 1000 nm). May be. The colorant particles may be surface-modified, and conventionally known ones can be used as the surface modifier.

<< Preparation Method of Colorant Particle Dispersion >>
The colorant is directly put into an aqueous medium containing a surfactant and dispersed by applying a shearing force. For example, it describes in Unexamined-Japanese-Patent No. 2000-292773.

  That is, a surfactant is contained by the action of shearing force generated by the screen that forms the stirring chamber and the rotor that rotates at a high speed in the stirring chamber (in addition, the action of collision force, pressure fluctuation, cavitation, potential core). A colorant is dispersed in an aqueous medium to prepare a dispersion of colorant particles.

  The mass average particle diameter (dispersion particle diameter) of the colorant particles is 30 to 500 nm, preferably 50 to 300 nm. When this mass average particle diameter is less than 30 nm, the suspension in the aqueous system becomes intense and it becomes difficult to incorporate the particles into the region A particles. On the other hand, when the mass average particle diameter exceeds 500 nm, the colorant particles are not appropriately dispersed in the aqueous system and are liable to settle, making it difficult to introduce into the region A particles and coloring in the free state. It becomes easy to generate the agent. The mass average particle diameter of the colorant particles is a value measured using an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.).

  The particle size distribution of the colorant particles is preferably 30 or less with a standard deviation, and more preferably 20 or less. When the particle size distribution of the colorant particles is 30 or less in standard deviation, the distribution can be sharpened, the colorant particles can be reliably taken into the region A particles, and the colorant particles are liberated. It becomes difficult to do. The “particle size distribution of the colorant particles” indicates a standard deviation measured by an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.).

  The colorant particles used to obtain the region A particles are prepared by adding a colorant into an aqueous medium containing a surfactant and predispersing (coarsely dispersing) with a propeller stirrer (colorant) The dispersion of the agglomerated particles) is supplied to a stirrer provided with a screen that forms a stirrer chamber and a rotor that rotates at high speed in the stirrer chamber, and is dispersed (finely dispersed) by the stirrer Prepared.

  Examples of the stirring device that can be used in the dispersion treatment for obtaining the colorant particles include “CLEARMIX” (manufactured by M Technique Co., Ltd.). This “Clearmix” is composed of a rotor (stirring blade) that rotates the liquid to be treated at a high speed and a fixed screen (stationary ring) that surrounds the rotor. It has a structure that produces the above action, and emulsifies and disperses by synergistic effects of these actions. That is, this “Clear mix” is used for the production of emulsion (dispersion of liquid particles), but the present inventors disperse the colorant particles (solid) in an aqueous medium. By using this as a dispersing device, a dispersion of colorant particles having a suitable average particle size and sharp particle size distribution is obtained.

(Region A particle)
The region A particles contain the resin particles (a) forming the region A, a colorant, and, if necessary, a fixing aid and a release agent.

(Preparation of region A particle dispersion)
The method for preparing the region A particle dispersion is not particularly limited as long as the region A particles satisfy the above-described conditions, but the viewpoint of fixing the resin particles (b) that form the region B on the surface of the region A particles. From the above, it is preferable to produce by an emulsion association method.

  Specifically, the resin particles (a) forming the region A, the colorant, and if necessary, a fixing aid and a release agent are mixed and agglomerated to obtain a predetermined size (2.5 to 9.0 μm). ), A salt is added to stop agglomeration and fused to prepare a region A particle dispersion.

  The particle size of the region A particles is in the range of 2.5 to 9.0 μm in terms of volume average particle size, and preferably 3.5 to 7.0 μm. Here, the volume average particle size can be measured by an electrical resistance type particle size distribution measuring device such as “Coulter Multisizer” (manufactured by Coulter Beckman) or “SD-2000” (manufactured by Sysmex).

  The area A particle concentration in the area A particle dispersion is preferably in the range of 4 to 35 mass%, more preferably 7 to 20 mass%. In this range, formation of the region B is promoted.

  Next, elements such as a fixing aid, a release agent, a colorant, and a surfactant used in the production of the region A particles according to the present invention will be described. The polymerizable monomer is as described above, and a description thereof is omitted here.

Fixing aid The toner region A according to the present invention may contain a fixing aid in order to control the softening point. Specific examples include vinyl polymers having a number average molecular weight of 1,500 to 3,500, and polymers of α-olefins such as poly-1-butene.

  Specific examples of the above-mentioned fixing aid include poly-1-butene (number average molecular weight 2000).

Release Agent A known release agent can be used for the toner according to the present invention. Preferable mold release agents include those represented by the following general formula.

General formula
R _1- (OCO-R ₂ ) n
In formula, n represents the integer of 1-4, Preferably it is 1-4, More preferably, it is 1-2.

R ₁ and R ₂ represent a hydrocarbon group which may have a substituent.

R ₁ : carbon number = 1-40, preferably 1-30, more preferably 16-26
R ₂ : carbon number = 1-40, preferably 14-30, more preferably 16-26
Among the ester compounds represented by the above general formula, behenyl behenate, stearyl stearate, behenyl stearate, stearyl behenate and the like are preferable. In addition, paraffin wax modified with a polar group, higher alcohol, and the like are preferably used.

  The content of the release agent is preferably 1 to 30% by mass of the total amount of toner particles.

Colorant As the colorant, conventionally known organic pigments and dyes can be used as well, and specific organic pigments and dyes are exemplified below.

  Examples of the magenta or red pigment include C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. And CI Pigment Red 222.

  Examples of the pigment for orange or yellow include C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. Pigment yellow 138, C.I. I. Pigment yellow 180, C.I. I. Pigment yellow 185, C.I. I. Pigment yellow 155, C.I. I. And CI Pigment Yellow 156.

  Examples of green or cyan pigments include C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. And CI Pigment Green 7.

  Examples of the dye include 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 black pigment include carbon black such as furnace black, channel black, acetylene black, thermal black and lamp black, and magnetic powder such as magnetite and ferrite.

  These organic pigments and dyes can be used alone or in combination as required. Moreover, the addition amount of a pigment is 2-20 mass% with respect to a polymer, Preferably it is 3-15 mass%.

Surfactant In the production process of the toner particles according to the present invention, it is preferable to disperse oil droplets in an aqueous medium using a surfactant. The surfactant that can be used in this case is not particularly limited, and the following ionic surfactants can be given as examples of suitable compounds.

  Examples of the ionic surfactant include sulfonate (sodium dodecylbenzenesulfonate, sodium arylalkylpolyethersulfonate, 3,3-disulfonediphenylurea-4,4-diazo-bis-amino-8-naphthol- 6-sulfonate sodium, ortho-carboxybenzene-azo-dimethylaniline, 2,2,5,5-tetramethyl-triphenylmethane-4,4-diazo-bis-β-naphthol-6-sulfonate sodium, etc.) , Sulfate salts (sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, etc.), fatty acid salts (sodium oleate, sodium laurate, sodium caprate, sodium caprylate, sodium caproate, stearyl Potassium, calcium oleate and the like).

  Moreover, it is preferable to use together the surfactant of the following general formula (1), (2).

Formula (1) R ₁ (OR ₂ ) _n OSO ₃ M
Formula (2) R ₁ (OR ₂ ) _n SO ₃ M
In the general formulas (1) and (2), R ₁ represents an alkyl group or arylalkyl group having 6 to 22 carbon atoms, preferably an alkyl group or arylalkyl group having 8 to 20 carbon atoms, more preferably It is a C9-16 alkyl group or arylalkyl group.

In the general formulas (1) and (2), R ₂ represents an alkylene group having 2 to 6 carbon atoms, preferably an alkylene group having 2 to 3 carbon atoms. Examples of the alkylene group having 2 to 6 carbon atoms represented by R ₂ include an ethylene group, a trimethylene group, a tetramethylene group, a propylene group, and an ethylethylene group.

  In general formula (1), (2), n is an integer of 1-11, Preferably it is 2-10, More preferably, it is 2-5, Most preferably, it is 2-3.

  In the general formulas (1) and (2), examples of the monovalent metal element represented by M include sodium and lithium. Of these, sodium is preferably used.

  Specific examples of the surfactant represented by the general formulas (1) and (2) are shown below, but the present invention is not limited thereto.

Compound _{(101): C 10 H 21} (OCH 2 CH 2) 2 OSO 3 Na
Compound _{(102): C 10 H 21} (OCH 2 CH 2) 3 OSO 3 Na
Compound _{(103): C 10 H 21} (OCH 2 CH 2) 2 SO 3 Na
Compound _{(104): C 10 H 21} (OCH 2 CH 2) 3 SO 3 Na
Compound (105): C ₈ H ₁₇ (OCH ₂ CH (CH ₃ )) ₂ OSO ₃ Na
Compound (106): C ₁₈ H ₃₇ (OCH ₂ CH ₂ ) ₂ OSO ₃ Na
In the production process of the toner particles according to the present invention, there is a process of aggregating resin particles from a dispersion of resin particles prepared in an aqueous medium, and a metal salt is preferably used as an aggregating agent as described above. As a specific flocculant, a divalent or trivalent metal salt is preferably used as the flocculant, and the divalent or trivalent metal salt is more critical than the monovalent metal salt. A coagulation point is small, which is preferable.

  The critical flocculation concentration referred to in the present invention is an index relating to the stability of the dispersion in the aqueous dispersion, and indicates the addition concentration of the flocculating agent when the flocculating agent is added. This critical coagulation concentration varies greatly depending on the latex itself and the dispersant. For example, it is described in Seizo Okamura et al., Polymer Chemistry 17,601 (1960), etc., and the value can be known by following these descriptions.

  As another method, a desired salt is added to the target particle dispersion at different concentrations, the ζ potential of the dispersion is measured, and the salt concentration at the point where the ζ potential starts to change is defined as the critical aggregation concentration. It is also possible to do.

(Resin particles forming region B (b))
For the resin particles (b) forming the region B, the type of the polymerizable monomer and the blending ratio thereof are selected so that the Tg is 50 to 65 ° C., and the molecular weight is 10,000 to 35,000. Resin particles obtained by polymerizing are preferred.

  Note that the Tg of the region B matches the Tg of the resin particles (b) forming the region B.

  The volume average primary particle diameter of the resin particles (b) forming the region B is preferably 50 to 240 nm. The volume average particle size and particle size distribution of the resin particles (b) forming the region B are obtained from numerical values measured by a laser Doppler type measuring device “UPA150” (manufactured by Microtrack). Specifically, the dispersion liquid is irradiated with laser light, and the interval of interference fringes generated by reflected light from the resin particles moving in the liquid in a latex micelle state is measured and calculated to obtain a particle size distribution.

(Preparation of dispersion of resin particles (b) forming region B)
As the dispersion of the region B particles, an aqueous dispersion obtained by dispersing the resin particles (b) obtained by polymerizing the polymerizable monomer into micelles is preferably used. The method for producing the dispersion of resin particles forming the region B is not particularly limited as long as the resin particles (b) can be made into micelles. Preferred methods include emulsion polymerization, miniemulsion polymerization, and seed polymerization. Is mentioned.

  The concentration of the resin particles (b) in the dispersion of the region B particles is preferably in the range of 5 to 50% by mass, more preferably in the range of 20 to 40% by mass.

(Method of adding a dispersion of resin particles (b) forming region B to region A particle dispersion)
In the present invention, the dispersion of the resin particles (b) forming the region B is added to the region A particle dispersion by 5 to 15 parts by mass of the resin particles (b) with respect to 100 parts by mass of the particles of the region A (resin particle conversion). Then, the resin particles (b) are fixed to the surface of the particles in the region A to a thickness of 1 μm or less to form the region B, thereby producing toner particles. Here, the term “adhesion” means that toner particles are formed by the action of mutual bonding forces such as adhesion, adsorption and electrostatic bonding between the region A particles and the resin particles (b) forming the region B. That's what it says.

  Since the resin particles (b) forming the region B do not become free particles in the dispersion but are firmly fixed to the surface of the region A particles, the polymerizable monomer structure of the region A particles and the resin particles (b) In the above, although phase separation is performed, it is necessary to devise a method for securely fixing, and it is preferable to include at least a monomer having a similar structure.

(Toner manufacturing process)
<< Manufacturing Process for Forming Region B on Region A Particle Surface >>
The toner particles according to the present invention are produced by fixing the resin particles (b) on the surface of the region A particles to form the region B. Specifically, the dispersion of resin particles (b) is added to the region A particle dispersion that is heated and stirred in several portions, and the resin particles (b) are fused to the surface of the region A particles.

  Thereafter, an aqueous solution in which sodium chloride is dissolved in 500 g of ion-exchanged water is added to further weaken the cohesive force of the particles, and heating and stirring are continued to completely fuse the resin particles (b) to the region A particles. Thereafter, the mixture is cooled, hydrochloric acid is added to adjust the pH, and stirring is stopped to prepare a toner particle dispersion.

<Solid-liquid separation and washing process>
In this solid-liquid separation / washing step, the toner particles are solid-liquid separated from the toner particle dispersion liquid obtained above to obtain a toner cake, and washings for removing deposits such as surfactants and aggregating agents from the toner cake are performed. Processing. Examples of the solid-liquid separation method include a centrifugal separation method, a reduced-pressure solid-liquid separation method performed using a Nutsche, etc., a solid-liquid separation method performed using a filter press, etc., but are not particularly limited. Absent. The washing method is not particularly limited as long as it can remove deposits such as a surfactant and an aggregating agent from the toner cake.

<< Drying process >>
This step is a step of drying the washed toner cake. 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 water content of the dried toner particles is preferably 5% by mass or less, and more preferably 2% by mass or less. In addition, when the toner particles subjected to the drying treatment are aggregated due to weak interparticle attraction, the aggregate may be crushed. Here, as the crushing treatment apparatus, a mechanical crushing apparatus such as a jet mill or an ejector can be used.

《External additive addition process》
In the toner of the present invention, the toner particles prepared as described above may be used as they are, but it is preferable to use so-called external additives for the purpose of improving fluidity and cleaning properties. . Specifically, particles having a primary particle size of 10 to 20 nm are used in order to impart fluidity to the toner, and particles of 20 to 300 nm are used in combination to improve transferability and keep the image carrier in contact with the toner clean. It is preferable to do. As an external additive that can be used in the present invention, inorganic fine particles such as silica, titania, alumina, and zinc oxide having relatively low resistance, organic fine particles, and a lubricant can be used.

  Examples of organic fine particles that can be used as an external additive include spherical fine particles having a number average primary particle diameter of about 10 to 2000 nm. Examples of the constituent material of the organic fine particles include polystyrene, polymethyl methacrylate, and styrene-methyl methacrylate copolymer. Examples include coalescence. These are effective in protecting an image carrier such as a photoreceptor and an intermediate transfer belt.

  Examples of the lubricant that can be used as an external additive include metal salts of higher fatty acids. Specific examples of the metal salt of the higher fatty acid include zinc stearate, aluminum stearate, copper stearate, magnesium stearate, calcium stearate and the like, stearic acid metal salt, zinc palmitate, copper palmitate, magnesium palmitate, palmitic acid. Examples thereof include metal palmitate such as calcium acid. The fatty acid unit is preferably a so-called saturated fatty acid having no double bond.

  The addition amount of the external additive is preferably about 0.1 to 5% by mass with respect to the toner. Examples of the apparatus for adding and mixing the external additive to the toner include mixing apparatuses such as a Turbuler mixer, a Henschel mixer, a Nauter mixer, and a V-type mixer.

(Preparation of developer)
The toner of the present invention can be used for a one-component developer or a two-component developer. When used as a one-component developer, a non-magnetic one-component developer or a magnetic one-component developer in which magnetic particles of about 0.1 to 0.5 μm are contained in the toner can be used.

  However, it is more preferable that the toner of the present invention is mixed with magnetic particles and used for a two-component developer. As the carrier used as the magnetic particles, conventionally known materials such as metals such as iron, ferrite and magnetite, and alloys of these metals with metals such as aluminum and lead can be used. Among these, ferrite particles are preferable. The magnetic particles preferably have a volume average particle size of 15 to 100 μm, more preferably 25 to 80 μm.

  The volume average particle diameter of the carrier can be typically measured by a laser diffraction particle size distribution measuring apparatus “HELOS” (manufactured by SYMPATEC) equipped with a wet disperser.

  The carrier is preferably a carrier in which magnetic particles are further coated with a resin, or a so-called resin dispersion type carrier in which magnetic particles are dispersed in a resin. The resin composition for coating is not particularly limited, and for example, olefin resin, styrene resin, styrene-acrylic resin, silicon resin, ester resin, or fluorine-containing polymer resin is used. In addition, the resin for constituting the resin-dispersed carrier is not particularly limited, and a known resin can be used. For example, a styrene-acrylic resin, a polyester resin, a fluorine resin, a phenol resin, or the like is used. be able to.

  Next, an image forming method performed using the toner of the present invention will be described.

  The image forming method using the toner of the present invention is not particularly limited. The toner fixing means of the present invention fixes the toner image by passing the transfer material between the pressure roller and the heating roller, between the belt and the heating roller, or between the soft roller and the heating roller. Fixing means is preferred.

  The toner of the present invention can be fixed at a high speed and with a low heat amount by using the fixing means, and can form a good toner image on a recording medium such as thin paper, coated paper or cardboard.

  The set temperature of the heating roller is preferably set to a condition where the temperature of the transfer material surface is 80 to 98 ° C., and is set to 100 to 150 ° C., for example. The surface temperature of the transfer material is measured by attaching a non-contact thermometer or a label coated with a temperature indicating material. The nip width of the heating roller is set to 8 to 40 mm, preferably 11 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.

[Heat roller fixing]
FIG. 2 is a schematic view showing an example of an image forming apparatus (thermal fixing roller fixing) used in the image forming method according to the present invention.

  In FIG. 2, reference numeral 50 denotes a photosensitive drum (photosensitive member) which is an image bearing member, and is a photosensitive member in which an organic photosensitive layer is coated on a drum and a resin layer is coated thereon. It is rotated. Reference numeral 52 denotes a scorotron charger (charging means) for uniformly charging the circumferential surface of the photosensitive drum 50 by corona discharge. Prior to the charging by the charger 52, the peripheral surface of the photosensitive member may be discharged by performing exposure by the pre-charging exposure unit 51 using a light emitting diode or the like in order to eliminate the history of the photosensitive member in the previous image formation.

  After uniform charging of the photoreceptor, image exposure based on the image signal is performed by an image exposure unit 53 as an image exposure unit. The image exposure unit 53 in this figure uses a laser diode (not shown) as an exposure light source. Scanning on the photosensitive drum is performed by the light whose optical path is bent by the reflection mirror 532 through the rotating polygon mirror 531 and the fθ lens, and an electrostatic latent image is formed.

  The surface of the photoconductor is uniformly charged by the charger 52, and an image exposed area, that is, an exposed area potential (exposed area) of the photoconductor is visualized by a developing process (means). On the other hand, the unexposed portion potential is not developed by the developing bias potential applied to the developing sleeve 541.

Next, the electrostatic latent image is developed by a developing device 54 as developing means. A developing device 54 containing a developer composed of toner and carrier is provided on the periphery of the photosensitive drum 50, and development is performed by a developing sleeve 541 that contains a magnet and rotates while holding the developer. The inside of the developing device 54 is composed of developer agitating / conveying members 544 and 543, a conveying amount regulating member 542 and the like. The developer is agitated and conveyed and supplied to the developing sleeve. The supply amount is controlled by the conveying amount regulating member. Be controlled. The amount of the developer transported varies depending on the linear velocity of the applied organic electrophotographic photosensitive member and the specific gravity of the developer, but is generally in the range of ^{20 to} 200 mg / cm ² .

  The toner according to the present invention can be used as either a two-component developer or a one-component developer. The diameter of the developing sleeve (developing roller) is 20 to 5 mm, preferably 18 to 7 mm, and the linear velocity of the developing sleeve is preferably 200 to 1800 mm / sec.

  Reference numeral 70 in the figure denotes a detachable process cartridge in which a photoconductor, a charger, a transfer device, a separator, and a cleaning device are integrated. Since the toner according to the present invention can be developed at high speed with a small developing device having a diameter in the above-described range, it is particularly preferably used for an image forming apparatus of a process cartridge specification.

[Belt fixing]
FIG. 3 is a schematic view showing an example of a fixing device using a belt and a heating roller in order to secure a nip width.

  In FIG. 3, the fixing roller 601, the seamless belt 11, the pressure pad (pressure member) 12 a that is pressed against the fixing roller 601 through the seamless belt 11, the pressure pad (pressure member) 12 b, and the lubricant supply member 40. The main part is composed.

  The fixing roller 601 is formed by forming a heat-resistant elastic body layer 10b and a release layer (heat-resistant resin layer) 10c around a metal core (cylindrical metal core) 10a. A halogen lamp 14 is disposed as a heating source. The temperature of the surface of the fixing roller 601 is measured by the temperature sensor 15, and the halogen lamp 14 is feedback controlled by a temperature controller (not shown) based on the measurement signal, so that the surface of the fixing roller 601 is adjusted to a constant temperature. The seamless belt 11 is in contact with the fixing roller 601 so as to be wound at a predetermined angle, thereby forming a nip portion.

  Inside the seamless belt 11, a pressure pad 12 having a low friction layer on the surface is disposed in a state of being pressed against the fixing roller 601 via the seamless belt 11. The pressure pad 12 is provided with a pressure pad 12a to which a strong nip pressure is applied and a pressure pad 12b to which a weak nip pressure is applied, and is held by a holder 12c made of metal or the like.

  Further, a belt traveling guide is attached to the holder 12c so that the seamless belt 11 smoothly slides and rotates. The belt running guide is preferably a member having a low coefficient of friction because it rubs against the inner surface of the seamless belt 11, and a member having low thermal conductivity is preferred so that heat is not easily taken from the seamless belt 11.

[Soft roller fixing]
FIG. 4 is a schematic view showing an example of a fixing device using a soft roller and a heating roller that secures a fixing nip and prevents winding of a transfer material and has excellent image quality.

  The fixing device 60 according to the present invention has the configuration shown in FIG. 4, and uses a heating roller 601 as a heating roller member and a soft roller 17 b as a soft roller member, and a halogen as a heating member inside the heating roller 601. A lamp 14 is provided.

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

  The transfer material used in the present invention is a support for holding a toner image, and is usually called an image support, a transfer material or a transfer paper. Specific examples include various types of transfer materials such as plain paper from thin paper to thick paper, coated printing paper such as art paper and coated paper, commercially available Japanese paper and postcard paper, plastic films for OHP, and cloth. However, it is not limited to these.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these.

1. Production Step of Resin Particle (b) Forming Resin Region B <Production of Resin Particle (b1)>
A polymerizable monomer solution (b1-1) was prepared using the following polymerizable monomer.

2-Ethylhexyl methacrylate 29.5 parts Styrene 66.0 parts Methacrylic acid 4.5 parts To a separable flask equipped with a stirrer, temperature sensor, condenser, and nitrogen inlet, an anionic surfactant (C ₁₂ H ₂₅ OSO ₃ Na) (1) 7.08 g was dissolved in 3010 g of ion-exchanged water, and the internal temperature was raised to 80 ° C. while stirring under a nitrogen stream to prepare a surfactant solution.

  An initiator solution prepared by dissolving 9.2 g of a polymerization initiator (potassium persulfate: KPS) in 200 g of ion-exchanged water is added to the surfactant solution, and the temperature is set to 75 ° C. Resin particles forming a solution (b1-1) added over 1 hour, and after completion of the addition, the system is polymerized by heating and stirring at 75 ° C. for 2 hours to become a raw material of the resin region B Was prepared. This is designated as “resin particles (b1)”. The resin particles (b1) had an SP value of 10.41 and a glass transition temperature of 62.5 ° C.

<Preparation of resin particles (b2)>
The procedure is the same as “Resin Particles (b1)” except that the polymerizable monomer used is changed to 2-ethylhexyl methacrylate 30.0 parts styrene 65.0 parts methyl methacrylate 2.5 parts methacrylic acid 2.5 parts “Resin particles (b2)” were produced. The resin particles (b2) had an SP value of 10.33 and a glass transition temperature of 60.4 ° C.

<Preparation of resin particles (b3)>
The procedure was the same as “Resin particles (b1)” except that the polymerizable monomer used was changed to 2-ethylhexyl methacrylate 30.0 parts styrene 17.5 parts methyl methacrylate 50.0 parts methacrylic acid 2.5 parts “Resin particles (b3)” were produced. The resin particles (b3) had an SP value of 9.98 and a glass transition temperature of 61.5 ° C.

<Preparation of resin particles (b4)>
“Resin particles (b4)” was prepared in the same procedure as “Resin particles (b1)” except that the polymerizable monomer used was changed to 2-ethylhexyl methacrylate 32.0 parts methyl methacrylate 66.0 parts methacrylic acid 2.0 parts. ) ”. The resin particles (b4) had an SP value of 9.83 and a glass transition temperature of 59.0 ° C.

<Preparation of resin particles (b5)>
“Resin particles (b5)” were prepared in the same manner as “resin particles (b1)” except that the polymerizable monomer used was changed to 36.0 parts of 2-ethylhexyl methacrylate and 64.0 parts of methyl methacrylate. The resin particles (b5) had an SP value of 9.73 and a glass transition temperature of 52.6 ° C.

2. Step of Producing Resin Particles (a) Forming Resin Region A 2-1) Production of Resin Particles (a1) Hereinafter, resin particles (a1) forming the resin particles A for base resin regions were produced by two-stage polymerization. .

  In a flask equipped with a stirrer, 70.0 parts of a mold release agent (pentaerythritol tetrabehenate) was added to a mixture of the following polymerizable monomers, heated to 80 ° C. and dissolved. This is designated as “polymerizable monomer solution (2-1-1)”.

<Polymerizable monomer solution (2-1-1)>
Styrene 57.0 parts n-Butyl acrylate 36.0 parts Methacrylic acid 7.0 parts On the other hand, the following anionic surfactant (2) 2.5 was added to a separable flask equipped with a stirrer, a temperature sensor and a condenser. A surfactant solution was prepared by dissolving 1 part in 1340 parts of ion-exchanged water.

(2) Anionic surfactant: C ₁₂ H ₂₅ (OCH ₂ CH ₂ ) ₂ OSO ₃ Na
After heating the surfactant solution to 80 ° C., a polymerizable monomer solution (2-1-1-) was obtained using a mechanical disperser “CLEARMIX” (manufactured by M Technique Co., Ltd.) having a circulation path. 1) was mixed and dispersed for 2 hours to prepare an emulsified liquid (dispersed liquid) containing emulsified particles (oil droplets) having a dispersed particle diameter (482 nm).

  Next, after adding 1460 parts of ion-exchanged water, an initiator solution in which 7.5 parts of a polymerization initiator (potassium persulfate: KPS) was dissolved in 142 parts of ion-exchanged water, 6.74 parts of n-octanethiol, Was added and the system was heated and stirred at 80 ° C. for 3 hours to carry out polymerization (first-stage polymerization) to obtain resin particles (a dispersion of high molecular weight resin particles). This is referred to as “resin particles (a1-1) forming the resin region A”.

  To this, an initiator solution in which 11.6 parts of a polymerization initiator (KPS) was dissolved in 220 parts of ion-exchanged water was added, and then the following polymerizable monomer solution (2 -1-2) was added dropwise over 1 hour.

<Polymerizable monomer solution (2-1-2)>
Styrene 55.5 parts n-Butyl acrylate 36.0 parts Methacrylic acid 8.5 parts Poly-1-butene (number-average molecular weight 2000) 4.0 parts Polymerization by heating and stirring for 2 hours after completion of dropping (second After step polymerization), the mixture was cooled to 28 ° C. to obtain a dispersion of resin particles (a1) using resin particles (a1-1) as raw materials. The resin particles (a1) had an SP value of 10.53 and a Tg of 29.9 ° C.

2-2) Step of forming resin region A (aggregation step)
The colorant particles and the resin particles (a1) were aggregated using the following colorant dispersion and the above resin particle (a1) dispersion.

<Preparation of colorant dispersion>
The above-mentioned anionic surfactant (2) 59.0 parts was dissolved in 1600 g of ion-exchanged water with stirring, and while stirring this solution, 420.0 parts of carbon black (Regal 330) was gradually added. A dispersion of colorant particles was prepared by performing a dispersion treatment using “Mix” (manufactured by M Technique Co., Ltd.). The particle diameter of this colorant dispersion was 93 nm.

<Aggregation process>
Resin particle (a1) dispersion 300.0 parts (in terms of solid content), ion-exchanged water 1120 parts, and 237 parts of the above-mentioned colorant dispersion, a temperature sensor, a cooling pipe, a nitrogen introducing device, and a stirring device It stirred in the attached four necked flask. After adjusting the temperature in the container to 30 ° C., the pH was adjusted to 10 by adding a 5 mol / liter sodium hydroxide aqueous solution.

  Next, an aqueous solution in which 55.3 parts of magnesium chloride hexahydrate was dissolved in 55.3 g of ion-exchanged water was added at 30 ° C. over 10 minutes with stirring. After standing for 3 minutes, the temperature was started to rise, and the system was heated to 90 ° C. over 60 minutes to aggregate the resin particles (a1) and the colorant particles.

  While continuing the stirring and heating, the particle size of the aggregated particles was measured with “Coulter Counter TA-II” (manufactured by Beckman Coulter), and when the volume-based median diameter became 5.5 μm, sodium chloride 15. An aqueous solution prepared by dissolving 3 parts in 100 g of ion-exchanged water was added to suppress particle growth.

3. Step of fixing resin particle b to resin region A 3-1) Dispersion liquid of toner particle 1 60 g (in terms of solid content) of resin particle dispersion liquid (b1) was added to 5 mol / liter sodium hydroxide aqueous solution to pH 8. Prepared.

  On the other hand, the heating and stirring of the resin region A dispersion liquid is continued for about 1 hour or more, and when the circularity becomes 0.936, the amount of the above-mentioned surface resin particle dispersion liquid (b1) is divided into four times four times. The resin particles b were fused and added to the surface of the resin region A to form the resin region B.

  Thereafter, an aqueous solution in which 123.9 parts of sodium chloride was dissolved in 500 parts of ion-exchanged water was added to further weaken the cohesive force of the particles, and the stirring was continued for 2 hours at 95 ° C. The fusion to A was completed and heating and stirring were continued. Then, it cooled to 30 degreeC on the conditions of 8 degreeC / min, hydrochloric acid was added and it adjusted to pH2, and stirring was stopped. This is referred to as “dispersion of toner particles 1”.

3-2) Toner Particle 2 Dispersion “Toner Particle 2 Dispersion” in the same manner as the adjustment of the toner particle 1 dispersion except that the resin particle dispersion (b1) is changed to the resin particle dispersion (b2). Got.

3-3) Dispersion of toner particles 3 “Dispersion of toner particles 3” in the same manner as the dispersion of toner particles 1 except that the resin particle dispersion (b1) is changed to the resin particle dispersion (b3). Got.

3-4) Dispersion of toner particles 4 “Dispersion of toner particles 4” in the same manner as the dispersion of toner particles 1 except that the resin particle dispersion (b1) is changed to the resin particle dispersion (b4). Got.

3-5) Dispersion of toner particles 5 “Dispersion of toner particles 5” in the same manner as the dispersion of toner particles 1 except that the resin particle dispersion (b1) is changed to the resin particle dispersion (b5). Got.

3-6) Toner Particle 6 Dispersion Toner particles 3 were produced in the same manner except that 60 g (in terms of solid content) of the resin particle dispersion (b3) was added to 15 g. 6 dispersion was obtained.

3-7) Dispersion of Toner Particles 7 In the production of the dispersion of toner particles 1, toner particles were similarly prepared except that 60 g (in terms of solid content) of the resin particle dispersion (b3) was added to 120 g. A dispersion of 7 was obtained.

3-8) Dispersion of Comparative Toner Particles 1 A dispersion of Comparative Toner Particles 1 was obtained by aggregating the resin particles (a1) and the colorant particles described above.

4). Solid-Liquid Separation / Washing Step The toner particle dispersion prepared above was subjected to solid-liquid separation using a centrifugal dehydrator to prepare a toner cake. The toner cake was washed while sprayed with ion exchange water at 40 ° C.

5. Drying process The toner cake that has been washed is dried by using a spray dryer until the water content in the toner becomes 2% by mass or less with warm air of 40 ° C., and “Toner Particles 1 to 7” and “Comparative Toner Particle 1” are used. Was made.

  Table 1 shows the characteristics of the toner particles prepared above.

6). External additive treatment step Next, hydrophobic silica (number average primary particle size = 12 nm, hydrophobization degree = 68) is added to each of “toner particles 1 to 7” and “comparative toner particles 1” produced above. 1% by mass and 1% by mass of hydrophobic titanium oxide (number average primary particle size = 20 nm, degree of hydrophobicity = 63), mixed by “Henschel mixer” (manufactured by Mitsui Miike Chemical Co., Ltd.), and then sieved with 45 μm openings. Coarse particles were removed using “Toner 1-7” and “Comparative Toner 1”.

7). Preparation of Developer For each of “Toners 1 to 7” and “Comparative Toner 1” produced above, a ferrite carrier having a volume average particle diameter of 60 μm coated with a silicone resin is used, and the concentration of the toner becomes 6% by mass. Thus, “Developers 1 to 7” and “Comparative developer 1” were prepared.

8). Evaluation Experiment As shown in Table 1, “Toners 1 to 7 (Developers 1 to 7)” are referred to as “Examples 1 to 7”, and “Comparative Toner 1 (Comparative Developer 1)” is referred to as “Comparative Example 1”. The following evaluation was performed.

  Using a commercially available multifunction machine “Sitoos 7035” (manufactured by Konica Minolta Co., Ltd.) adopting an electrophotographic system, the linear velocity is 280 mm (about 50 sheets / min), the developing roller is 9 mm, and the fixing device has the configuration shown in FIG. The printer was changed to a fixing device (a polyimide seamless belt was used as the fixing pressure member), and printing was performed to create a printed image. The state of the multifunction device and the print image were evaluated for the following evaluation items.

<Charging speed>
1000 sheets were printed in a print mode in which the pixel rate was 75%, and the toner consumption and replenishment amount were remarkably large, and toner spillage in the machine and image blur of the printed image were visually evaluated.

Evaluation criteria A: No toner spillage due to poor charging, no image blurring ○: No toner spillage due to charging failure, but slight blurring occurred at the trailing edge of the print, but there was no practical problem ×: Toner spillage due to poor charging, image It is a problem for practical use.

<Charge retention>
After leaving at high temperature and high humidity (30 ° C., 90% RH) for 72 hours, printing was performed under the same development conditions as before, and the printed image was visually evaluated.

Evaluation Criteria A: Gradation variation is not visually confirmed. O: Light color (halftone), photographic image feels dark, but no problem for practical use. X: Three-point character “e” cannot be distinguished, which is a practical problem.

<Heat resistant storage>
100 g of each toner was allowed to stand at 55 ° C. and 90% RH for 24 hours, and then sieved with a sieve having an opening of 45 μm. The amount (ratio) of the aggregate remaining on the sieve was heat-resistant storage stability (toner storage stability). Evaluated.

Evaluation Criteria ◎: Less than 5% on the sieve, very little aggregation and excellent (no generation of aggregates even if transported in summer without any insulation packaging)
○: The amount on the sieve is 5-30% and the amount of agglomeration is small and good (no agglomeration even if transported in the summer with cardboard packaging only)
X: The amount on the sieve is more than 30%, the amount of aggregation is large, and there is a practical problem (needs cold transport).

<Minimum fixing temperature>
The surface temperature of the heating roller of the fixing device of the evaluation machine was changed so that the paper surface temperature changed in increments of 10 ° C. within the range of 80 to 150 ° C., and the toner image was fixed at each changed temperature to produce a fixed image. . In producing the print image, high-quality paper (80 g / m ² ) of A4 size was used.

  The fixing strength of the printed image obtained by fixing is fixed using a method in accordance with the mending tape peeling method described in Chapter 9 Section 1.4 of “Basics and Applications of Electrophotographic Technology: Electrophotographic Society”. The rate was evaluated.

Specifically, after producing a 2.54 cm square solid black print image with a toner adhesion amount of 0.6 mg / cm ² , the image density before and after peeling with “Scotch Mending Tape” (manufactured by Sumitomo 3M). And the residual ratio of the image density was determined as the fixing ratio.

  The “transfer material (paper) surface temperature” at which the fixing rate is 95% or more is defined as the minimum fixing temperature. The surface temperature of the transfer material (paper) was measured with a non-contact thermometer. The image density was measured with a reflection densitometer “RD-918” (manufactured by Macbeth).

Evaluation criteria A: Fixing is possible at a minimum fixing temperature of less than 95 ° C. ○: Fixing is possible at a minimum fixing temperature of 95 ° C. or more and less than 105 ° C. : Fixing is possible at a minimum fixing temperature of 120 ° C or higher.

<Thin paper wrinkles>
Using 40 g / m ² of thin paper as a transfer material, 20 solid images (A4 size) were printed out. The 20 prints obtained were visually evaluated and wrinkles were evaluated according to the following evaluation criteria.

Evaluation criteria A: No occurrence of wrinkles B: Generation of wrinkles was less than 2 on average ×: Generation of wrinkles was 2 or more on average

<Glossy coated paper image defects>
Glossy coated paper (manufactured by Mitsubishi Paper Industries Co., Ltd., Tokishi Art, 75 g / m ² ) was used as a transfer material, and 20 (A4 version) solid images (solid black images) were printed out. The white spots with a diameter of 1 mm or more in the solid image were visually counted, and the image defect of the glossy coated paper was evaluated by the number of white spots.

Evaluation criteria ◎: Solid image has no white point mark ○: Solid image has 1 to 3 white spot marks on average 1 mm ×: White image has 1 mm or more white point marks on average 3 There were more than pieces.

  The evaluation results are shown in Table 2.

  As is clear from Table 2, “Examples 1 to 7” gave good results for all the evaluation items, but “Comparative Example 1” failed to find good results. In the evaluation of the minimum fixing temperature, those with “◎” confirmed that a good fixed image could be obtained even when the paper surface temperature was 80 ° C.

FIG. 3 is a schematic diagram showing a structure of toner particles according to the present invention. 1 is a schematic diagram illustrating an example of an image forming apparatus (heat fixing roller fixing) used in an image forming method according to the present invention. FIG. 3 is a schematic diagram illustrating an example of a fixing device using a belt and a heating roller in order to ensure a nip width. FIG. 3 is a schematic diagram illustrating an example of a fixing device that uses a soft roller and a heating roller that secure a fixing nip and prevent winding of a transfer material and is excellent in image quality.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor laser light source 2 Polygon mirror 3 f (theta) lens 4 Photosensitive drum 5 Charger 6 Developing device 7 Transfer device 8 Transfer paper 9 Separator 10 Fixing device 11 Cleaning device 12 Pre-charge exposure 13 Cleaning blade 71 Heating roller 72 Pressure roller 75 Heating member 81 Core metal of heating roller 82 Coating layer of heating roller 83 Metal core of pressure roller 84 Coating layer of pressure roller

Claims (5)

Consists of toner particles containing a resin and a colorant,
When the toner particles were cut into 100 nm sections and observed with a transmission electron microscope with an acceleration voltage of 80 kV,
The toner particles include a region A containing a colorant, and an alkyl group or alkylene group having 6 to 20 carbon atoms that can transmit electrons to the region within 1 μm from the surface of the toner particles. And a region B containing a vinyl polymer having a toner. The solubility parameter value of the resin contained in the region A and the region B is that the region B is lower than the region A, and the difference is 0.20 to 0.70. toner. The region B is made of a resin having a glass transition temperature of 50 to 65 ° C, and the region A is made of a resin containing a fixing aid and having a glass transition temperature of -20 to 39 ° C. The toner according to 1 . A toner production method for producing toner particles through a step of forming another region B around a region A containing a colorant,
The solubility parameter value of the resin contained in the region A and the region B is that the region B is lower than the region A, and the difference is 0.20 to 0.70.
The resin for forming the region B is formed using a polymerizable monomer having an alkyl group or alkylene group having 6 to 20 carbon atoms which may be branched. An image forming method using the toner according to claim 1, wherein the toner image is fixed on the transfer material by heating the surface temperature of the transfer material to 80 to 105 ° C.

Images