JP2008070726A - Toner and method for manufacturing the toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner which allows smooth removal of residual toner on a photoreceptor and a transfer belt by cleaning with a blade when image formation is performed using the substantially spherical toner. <P>SOLUTION: The toner is obtained by mixing a toner having a median diameter on a volume basis (D<SB>50</SB>) of 3-8 μm in which the length of a perpendicular line passing through a protrusion on an outer edge on a toner projected image is 0.5 to <1.0 time the major axis size of the toner with a toner having a perpendicular line of which the length is equal to the major axis size. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a toner used for electrophotographic image formation, and more particularly to a toner having a mixture of spherical and non-spherical shapes.

  In the field of electrophotographic image forming technology such as copiers and printers, full-color image forming devices represented by the tandem method have emerged along with the advancement of digital technology, resulting in high-quality, high-definition images such as photographs. Can be created (see, for example, Patent Document 1). As a result, color images of a level that could only be handled by printing can be obtained in the past, and even in the printing industry where electrophotographic image forming apparatuses are required to produce high resolution, wide color reproduction area, and high-speed printing. Photographic image forming apparatuses have been used.

  Further, high-definition image formation such as reproduction of a minute dot image of 1200 dpi (dpi; the number of dots per inch (2.54 cm)) is also studied, and means for accurately reproducing a minute dot image As one of these, various attempts have been made to reduce the diameter of the toner. Among them, a polymerized toner capable of forming a desired toner by controlling the shape and size of particles has been attracting attention (for example, see Patent Document 2).

  As described above, a technique for creating a high-quality, high-definition full-color image by an electrophotographic method by using a color image forming apparatus and a toner diameter-reducing technique is spreading in the market.

  By the way, from the viewpoint of consideration for the global environment or cost reduction on the user side, there is a tendency to reduce the power consumption of the image forming apparatus. As one of the countermeasures, the fixing is lower than the current situation. A so-called low-temperature fixing technique for forming an image at a temperature is drawing attention. As a means for solving this problem, for example, a polymerized toner that enables fixing at a low temperature by using a low melting point wax has been studied (for example, see Patent Document 3).

  In designing a toner that achieves low-temperature fixing, in addition to the above-described method of selecting a wax having a low melting point, a method of obtaining a toner having a low fixing temperature by selecting a resin is also included. That is, a resin having a low melt viscosity can be obtained by lowering the glass transition temperature or the molecular weight, and a toner having a low fixing temperature can be obtained by using such a resin.

A toner formed of a resin having a low melt viscosity is likely to have a shape close to a true sphere due to the influence of temperature at the time of production. Since the toner having a shape close to a true sphere accurately reproduces a fine dot image, it is convenient for forming a high-definition toner image such as a digital image.
Japanese Patent Laid-Open No. 10-20598 JP 2000-214629 A JP 2001-42564 A

  However, since toner particles are more likely to roll when they become nearly spherical, cleaning with a blade tends to slip through without being caught well at the edge, causing a problem that the cleaning with the blade cannot be performed smoothly. It was. As described above, the nearly spherical toner is advantageous for high-definition image formation, but cleaning failure due to slipping from the blade is likely to occur.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an electrostatic charge image developing toner capable of smoothly cleaning a residual toner on a photosensitive member or a transfer belt with a blade when an image is formed using a nearly spherical toner. To do. It is another object of the present invention to provide a toner for developing an electrostatic charge image that can be smoothly cleaned with a blade and can form a high-definition image and is compatible with low-temperature fixing.

  The present invention is achieved by adopting the following configuration.

1.
In a toner containing at least a resin and a colorant,
The toner is
The median diameter (D ₅₀ ) on a volume basis is 3 μm or more and 8 μm or less,
With respect to the major axis of the toner obtained when the toner is projected,
Toner having a perpendicular with the same length as the major axis is 50% to 70% of the total toner,
The toner having a length that is 0.5 times or more and less than 1.0 times the major axis and that has a perpendicular passing through the convex portion on the outer edge of the toner is 30% or more and 50% or less of the total toner. is there,
Toner characterized by the above.

2.
A toner having a length not less than 0.5 times the major axis and less than 1.0 times and having a perpendicular passing through a convex portion on the outer edge of the toner,
2. The toner according to 1, wherein the toner has at least three perpendicular lines passing through a convex portion on the outer edge of the toner.

3.
3. The toner according to 1 or 2, wherein the toner has an average circularity of 0.940 or more and 0.980 or less.

4).
4. The toner according to any one of 1 to 3, wherein a value of a coefficient of variation (CV value) with respect to the median diameter (D ₅₀ ) on the volume basis is 2% or more and 21% or less.

5.
5. The toner according to any one of 1 to 4, wherein the toner has a glass transition temperature of 10 ° C. or higher and 40 ° C. or lower.

6).
6. The toner according to any one of 1 to 5, wherein a softening point of the toner is 90 ° C. or higher and 120 ° C. or lower.

7).
The toner is produced through a process of aggregating at least two kinds of resin fine particles,
The step of aggregating the resin fine particles comprises adding resin fine particles having a glass transition temperature different from that of the resin fine particles initially added during the aggregation, and further continuing the aggregation. The toner according to any one of 1 to 6 above.

8).
8. The toner according to 7 above, wherein the resin fine particles added during the aggregation are those having a glass transition temperature higher than that of the resin fine particles added first.

9.
A method for producing a toner comprising a step of aggregating resin fine particles,
In the step of aggregating the resin fine particles,
A method for producing a toner, comprising adding resin fine particles having a glass transition temperature different from that of the first added resin fine particles during aggregation, and further continuing the aggregation.

10.
10. The method for producing a toner as described in 9 above, wherein the resin fine particles added during the aggregation are those having a glass transition temperature higher than that of the resin fine particles added first.

11.
The timing of adding resin fine particles with a glass transition temperature different from that of the first added resin fine particles
9 or 10 above, wherein the size of the aggregate composed of the resin fine particles added first is 30% to 50% of the median diameter (D ₅₀ ) on the volume basis of the toner. 2. A method for producing the toner according to 1.

  In the present invention, a toner in which a spherical toner and a non-spherical toner typified by a peanut shape are mixed so that the cleaning by the blade can be smoothly performed even if the spherical toner remains on the photosensitive member or the transfer belt. became. In other words, in the present invention, the presence of the non-spherical toner prevents the non-spherical toner from rolling and stopping its movement, preventing the spherical toner from slipping from the blade, and smoothing the cleaning of the spherical toner. It is presumed that it was possible to do it.

  Thus, according to the present invention, the problem of spherical toner blade cleaning, which has been a concern, has been solved, and a high-definition toner image can be stably formed. In addition, low-temperature fixing compatible toner that is easy to take a spherical shape can be actively used, reducing power consumption and stably forming high-definition toner images.

  The present invention relates to a toner in which a spherical toner and a non-spherical toner represented by a peanut shape are mixed.

  When an image is formed using the toner according to the present invention, the residual toner on the image carrier can be removed using a blade in the cleaning process. As described above, the reason why the cleaning with the blade can be smoothly performed even when spherical toner is present is that the non-spherical toner stops moving so that the spherical toner does not roll. This is presumed to prevent slipping of the spherical toner from the blade. In other words, the present invention is designed to prevent the spherical toner from rolling during cleaning with the non-spherical toner, and eliminates the slip of the spherical toner from the blade by mixing the non-spherical toner.

  Further, the toner according to the present invention is obtained through a process of producing resin particles by agglomerating and fusing resin fine particles of 100 nm level. By agglomeration and fusing, spherical particles and non-spherical shapes such as peanut shapes are obtained. These particles can be formed simultaneously. As described above, the reason why particles having different shapes can be formed simultaneously in one aggregation / fusion environment is not clear, but is presumably realized by the following mechanism.

  First, it is presumed that very random aggregation is performed in the initial stage of aggregation of resin fine particles, and particle formation with a very wide particle size distribution is performed. That is, the formed particles vary in size, and it is assumed that large particles and small particles are mixed.

  In the present invention, resin fine particles having a glass transition temperature higher than the resin fine particles initially added in the middle of the aggregation process are added to the reaction system, and the newly added resin fine particles are melted on the particle surface formed in the initial stage. Through the process of wearing, the environment where aggregation can be continued after that is maintained. At this time, agglomeration of small particles occurs predominantly, so the size is about the same as that of large particles, but the agglomerates of small particles have a round shape due to the effect of the high glass transition temperature resin adhering to the particle surface. It is unlikely that a non-spherical shape such as a peanut shape is formed.

  Hereinafter, the present invention will be described in detail.

  The toner according to the present invention is a mixture of spherical toner and non-spherical toner such as peanut shape. The shapes that the toner according to the present invention can take will be described with reference to FIG.

  FIG. 1 is a schematic diagram showing the shape of particles obtained when the toner T according to the present invention is projected by electron microscopic photography or the like, and FIGS. 1A to 1D show examples of non-spherical toner T. FIG. Yes, what is shown in (e) is the spherical Tona T-. In the figure, “major axis” in the present invention is indicated by L, “toner outer edge” is indicated by f, “projection on the toner outer edge” is indicated by p, and “perpendicular line passing through the protrusion” is indicated by r. In addition, although there is a thing with a number in the perpendicular line, this means a plurality of perpendicular lines.

  As shown in the figure, “outer edge (f) of toner” refers to a contour portion obtained when toner is projected, and “long axis (L)” is a line formed by connecting two points on the outer edge of toner particles. Of the minutes, the distance between the two points is the longest. Further, the “convex portion (p) on the outer edge of the toner” refers to a curved portion on the outer edge, and includes a curved portion on the inner side of the particle in addition to a curved portion on the outer side of the particle. Further, the “perpendicular line (r) passing through the convex portion” means a point where the differential value is 0 on the curve in the curved portion, that is, a line segment that passes through the tip of the curved portion and is orthogonal to the major axis. Is.

  First, the toner T shown in FIGS. 1A and 1B is an example of a non-spherical toner. In the present invention, “the major axis obtained when the toner is projected is 0.5 times or more and more than 1.0 times. This corresponds to “a toner having a small length and having a perpendicular line passing through a convex portion on the outer edge of the toner”. The toner T shown in FIG. 1A has a shape close to a spherical shape among non-spherical toners, and the length of the major axis is about 0.8 times or more and less than 1.0 times. A perpendicular line r having a diameter passes through the convex portion p on the toner outer edge f. In addition, the toner T shown in FIG. 1B has a shape that is longer than that of FIG. 1A, and a perpendicular line r having a length of about 0.5 times or more and less than 0.8 times the major axis L is a toner outer edge f. It passes through the upper projection p.

  Next, the toner T shown in FIGS. 1C and 1D is “passes the convex portion on the outer edge of the toner with respect to the major axis of the toner among the non-spherical toners shown in FIG. This corresponds to “a toner having at least three perpendiculars”. The “toner having at least three perpendicular lines passing through the convex portion on the outer edge of the toner with respect to the major axis of the toner” in the present invention has a shape like a peanut shown in FIG. The thing which has the elongate shape shown to (d) is mentioned. The toner T having the shape shown in FIG. 1D is formed by continuously forming innumerable convex portions p on the outer edge f, and has a shape like a straw at first glance.

  In addition, the toner T shown in FIG. 1E is a so-called “spherical toner”. In the present invention, the “toner whose perpendicular passing through the convex portion on the outer edge of the toner has the same length as the major axis” is used. It is shown.

  As described above, the toner according to the present invention is a mixture of the non-spherical toner T shown in FIGS. 1A to 1D and the spherical toner T shown in FIG. From 30% to 50% and spherical toner from 50% to 70%.

  In the present invention, the shape of the toner is specified by the long axis and the perpendicular passing through the convex portion on the outer edge of the toner, and the content of the toner having each shape is specified. It is possible to specify from the projection image. As a method for obtaining this projection image, for example, a micrograph obtained by a scanning electron microscope (SEM) can be mentioned, and the above-described matters can be specified by analyzing the micrograph.

  The major and minor axes and the major / minor axis ratio of the toner particles can be confirmed from the shape of the toner particles, and specifically, can be obtained from a micrograph obtained by a scanning electron microscope (SEM). Is possible. A method for specifying the shape of the toner and the content of the toner having each shape from a micrograph obtained by a scanning electron microscope (SEM) is performed by the following procedure.

(1) Sample preparation conditions The toner is set so that the shape of the toner can be specified with a scanning electron microscope (SEM). Specifically, the toner was spread on the medicine wrapping paper, a conductive double-sided tape was applied to the sample table, and the surface opposite to the surface on the sample table was lightly pressed against the toner on the medicine wrapping paper, and the conductive double-sided tape was not attached. Blow off the toner with a blower, and set the toner on the sample stage. At this time, the toner is set on the sample stage so that 100 or more randomly arranged toners are photographed.

  Thereafter, using a sputter coater “Emscope SC500 (manufactured by Emitech)”, a sample is prepared by performing Au—Pd coating (layer thickness: 7 nm) on the toner at a coating current of 10 to 15 mA under reduced pressure.

(2) Setting conditions of scanning electron microscope Using a scanning electron microscope “JSM-6400F (manufactured by JEOL Ltd.)”, observation is made at an acceleration voltage of 5 kV.

(3) Method for specifying toner shape by scanning electron microscope An electron micrograph is taken at a magnification of 2000 times. The photograph image obtained by photographing is taken into the scanner, and passes through the long axis of each toner, the convex portion on the outer edge, and the convex portion using the image processing analysis device “LUZEX AP (manufactured by Nireco Corporation)”. The perpendicular to be calculated is calculated by an arithmetic process. In this way, through the arithmetic processing by the image processing analysis apparatus, the shape of the toner contained from the data such as the perpendicular passing through the major axis and the convex portion and the content of the toner having each shape are calculated based on the number standard. To do.

The toner according to the present invention has a volume-based median diameter (D ₅₀ ) of 3 μm or more and 8 μm or less. By setting the median diameter (D ₅₀ ) on the volume basis within the above range, for example, a very small dot image of 1200 dpi (dpi; number of dots per inch (2.54 cm)) level is faithfully reproduced, and a spherical shape is obtained. The cleaning failure due to toner is also eliminated. Therefore, since the toner image is formed on the image carrier that has been sufficiently cleaned, it is possible to form a beautiful high-definition toner image without contamination, and the trouble of causing the printed matter at the same level as the printed image to cause a plate. It came to be obtained without spending. In particular, in the printing field called “on-demand printing” corresponding to the print order of several thousand sheets, it has been highly evaluated for its merit that it is possible to quickly deliver products in addition to high-quality images.

The median diameter (D ₅₀ ) on the volume basis of the toner can be measured and calculated using an apparatus in which a computer system for data processing is connected to “Multisizer 3 (manufactured by Beckman Coulter)”.

  As a measurement procedure, 0.02 g of toner is blended with 20 ml of a surfactant solution (for example, a surfactant solution obtained by diluting a neutral detergent containing a surfactant component 10 times with pure water for the purpose of dispersing the toner). After that, ultrasonic dispersion is performed for 1 minute to prepare a toner dispersion. This toner dispersion is injected into a beaker containing ISOTON II (manufactured by Beckman Coulter, Inc.) in a sample stand with a pipette until a measurement concentration of 5 to 10% is reached, and the measuring machine count is set to 2500. To do. Note that the aperture size of the multisizer 3 is 50 μm.

The toner according to the present invention preferably has a volume-based median diameter (D ₅₀ ) coefficient of variation (CV value) of 2% to 21%, and more preferably 5% to 15%.

The variation coefficient (CV value) of the median diameter (D ₅₀ ) on the volume basis represents the degree of dispersion in the particle size distribution of the toner particles on the volume basis, and is defined by the following equation. The smaller the CV value, the sharper the particle size distribution, and the larger the toner particle size. That is, since toners of uniform sizes can be obtained, it is possible to reproduce fine dot images and fine lines at the time of digital image formation with higher accuracy.

CV value (%) = (standard deviation in volume-based particle size distribution) / (volume-based median diameter (D ₅₀ )) × 100
The coefficient of variation of the median diameter (D ₅₀ ) on a volume basis can be measured and calculated using an apparatus in which a computer system for data processing is connected to “Multisizer 3 (manufactured by Beckman Coulter)”.

The toner according to the present invention preferably has an average circularity of 0.940 or more and 0.980 or less, and more preferably 0.945 or more and 0.965 or less.
. When the average circularity is in the above range, the fluidity of the spherical toner is sufficiently exhibited, and the progress of toner deterioration is prevented even if the mechanical load continues for a long time in the image forming apparatus. As a result, high-definition toner can be stably formed over a long period of time with a highly durable toner.

  The average circularity of the toner is a value calculated by dividing the sum of the circularity of the toner defined by the following formula by the total number of toners.

Circularity = (perimeter of a circle having the same projection area as the toner image) / (perimeter of the toner projection image)
The average circularity of the toner can be calculated using, for example, a flow particle image analyzer represented by “FPIA-2100 (manufactured by Sysmex)”.

  Specifically, the toner is blended with an aqueous solution containing a surfactant, dispersed by ultrasonic dispersion for 1 minute, and then “FPIA-2100” is used to detect the HPF in the measurement condition HPF (high magnification imaging) mode. Measurement is performed at appropriate concentrations of several thousand to 10,000. Within this range, reproducible identical measurement values can be obtained.

  The toner according to the present invention has a standard deviation of the average circularity (circularity SD) of 0.035 or more and 0.050 or less, and preferably 0.042 or more and 0.048 or less. In the present invention, the cleaning performance by the blade is improved by setting the standard deviation of the average circularity of the toner within the above range, that is, by varying the shape of the toner. That is, when toner image formation is performed using only spherical toner, the toner filling property on the image carrier becomes very high and the load on the blade becomes large because the toner image is formed only with toner of uniform shape. When an image is formed by mixing a toner with low circularity in such a toner, the toner filling state on the image carrier is relaxed, and the toner from the image carrier is reduced by the unevenness of the toner. It is presumed that removal will be easier.

  The standard deviation of the average circularity is obtained by calculating the sum of squares of the difference between the circularity of each toner and the average circularity calculated by the above formula, dividing this by the total number of toners, and taking the square root of the value. It is a thing.

In this way, non-spherical toner is mixed with spherical toner, and the average circularity and its standard deviation are specified, so that rolling of the spherical toner is suppressed to prevent the occurrence of slipping, and the toner on the image carrier The glass transition point (Tg) of the toner of the present invention, which is presumed to improve the cleaning property by relaxing the filling property, is preferably 10 ° C. or higher and 40 ° C. or lower in order to ensure low-temperature fixability.

  As the resin fine particles added during the aggregation, those having a glass transition temperature higher than that of the resin fine particles added first are used.

  The glass transition temperature of the resin fine particles added first is preferably 10 ° C. or higher and 40 ° C. or lower. The glass transition temperature of the resin fine particles added in the middle is preferably 40 ° C. or higher and 60 ° C. or lower.

  The glass transition temperature is typically measured by a differential calorimeter (DSC). As specific measuring devices, “DSC-7 differential scanning calorimeter (manufactured by PerkinElmer)”, “TAC7 / DX thermal analyzer”. Controller (manufactured by PerkinElmer) ".

  A specific method for measuring the glass transition temperature using a differential calorimeter is, for example, as a temperature rise / 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 Next, after being left at 100 ° C. for 1 minute, it is cooled to 0 ° C. under a condition of 10 ° C./min (first cooling step). 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 rising) and making it Tg is mentioned.

  The glass transition temperature Tg is determined by measuring the baseline extension line 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 rising portion to the peak apex. The temperature of the intersection point is defined as the glass transition temperature.

  As a specific procedure for measuring the glass transition temperature by the differential calorimeter, the toner 4.5 mg to 5.0 mg is precisely weighed to two digits after the decimal point, and enclosed in an aluminum pan (KIT No. 0219-0041). Set in the sample holder. The reference uses an empty aluminum pan. The measurement conditions were a measurement temperature of 0 ° C. to 200 ° C., a temperature increase rate of 10 ° C./min, a temperature decrease rate of 10 ° C./min, and heat-cool-heat temperature control. Analysis is performed based on the data in Heat.

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

  As a method of calculating the glass transition temperature, there is a method of calculating from the following theoretical glass transition temperature. Here, the theoretical glass transition temperature is a value obtained by multiplying the glass transition temperature obtained when each component constituting the copolymer resin forms a homopolymer and the composition mass fraction, and using these values. Calculated.

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

Formula (1)
1 / Tg '= W1 / Tg1 + W2 / Tg2 + ... + Wn / Tgn
(Wherein W1, W2,... Wn are the mass fraction of each polymerizable monomer relative to the total polymerizable monomer constituting the copolymer resin, and Tg1, Tg2,... Tgn are each polymerizable monomer. (The glass transition temperature (absolute temperature) of the homopolymer formed using the monomer is shown.)
The glass transition temperature can be controlled by changing the composition ratio of monomers constituting the vinyl copolymer. For example, a copolymer resin formed using styrene and butyl methacrylate. Then, it has been confirmed that the value of the glass transition temperature increases by increasing the composition ratio of styrene and decreasing the composition ratio of butyl methacrylate.

In the toner of the present invention, there may be some difference in the value of the theoretical glass transition temperature, the measurement result obtained with the differential calorimeter, or the result with the atomic force microscope. It does not deny the technical idea of or affect the results.
The temperature to be used may be the glass transition temperature Tg.

  The softening point (Tsp) of the toner of the present invention is preferably 90 ° C. or higher and 120 ° C. or lower, and more preferably 70 ° C. or higher and 100 ° C. or lower in order to ensure low temperature fixability.

  In this case, the fixing can be performed even when the temperature of the transfer material surface is 125 ° C. or lower. This is because, in the toner of the present invention, the area ratio of the core part (part composed of resin fine particles A) having a low softening point is about 70% on a mass basis with respect to the toner particles, and the shell part (resin having a high softening point) The softening point of the whole toner can be lowered by setting the amount of the resin constituting the portion (parts composed of the fine particles B) small, and the heat-resistant storage stability and durability of the toner can be ensured by the shell portion having a high softening point. It is possible. Therefore, the toner of the present invention can obtain good low-temperature fixability by setting the softening point temperature of the toner to 90 ° C. or higher and 120 ° C. or lower.

  Control of the softening point of the toner can be achieved, for example, by controlling the type of monomer constituting the resin used for forming the resin fine particles or the monomer composition ratio of the copolymer, or controlling the amount of the chain transfer agent. Examples include a method for controlling the degree of polymerization or a method for adjusting the type and amount of a fixing aid such as a wax (release agent) added to the toner. By combining these, a toner having a desired softening point can be obtained. It is done. An example is a method of controlling the softening point by plotting the relationship between the molecular weight and the softening point in a specific resin. Generally, when the molecular weight is increased, the softening point increases.

  The method for measuring the softening point temperature of the toner is specifically “Flow Tester CFT-500 (manufactured by Shimadzu Corporation)”, formed into a cylindrical shape with a height of 10 mm, and heated at a heating rate of 6 ° C./min. While applying a load of 200 kPa from the plunger and pushing from a nozzle with a diameter of 1 mm and a length of 1 mm, this draws a curve (softening flow curve) between the plunger drop amount and temperature of the flow tester and flows out first. The temperature is the melting start temperature, and the temperature with respect to the drop amount of 5 mm is the softening point temperature.

The toner according to the present invention contains at least a resin and a colorant, and as described above, a non-spherical toner and a spherical toner are mixed. In addition, the toner according to the present invention has a median diameter (D ₅₀ ) based on volume within the above-mentioned range, and a small diameter toner that faithfully reproduces a minute dot image controls the particle size and shape in the manufacturing process. It is preferable to produce by the polymerization method which can add operation. Among them, emulsification in which toner particles are prepared by forming resin particles of around 120 nm in advance by an emulsion polymerization method or suspension polymerization method, and a step of agglomerating the resin particles to form particles of the aforementioned size. It can be said that the association method is one of effective production methods.

  In the present invention, when the toner is prepared by the emulsion association method, it is found that the spherical toner and the toner having the above-mentioned non-spherical shape can be formed simultaneously by performing the following operations in the resin fine particle aggregating step. . That is, it is an operation in which resin fine particles are newly added during the aggregation of resin fine particles and the aggregation is continued. Specifically, in the middle of aggregating the resin fine particles, resin fine particles having a glass transition temperature different from the resin fine particles added first are added, and further the aggregation is continued. Those having a glass transition temperature higher than the first resin fine particles are preferred.

  Hereinafter, toner production by an emulsion association method, which is an example of a toner production method according to the present invention, will be described. Toner preparation by the emulsion association method is performed through the following steps.

(1) Preparation process of resin fine particle A dispersion (2) Preparation process of resin fine particle B dispersion (3) Preparation process of colorant fine particle dispersion (4) Aggregation / fusion process of resin fine particles (5) Aging process ( 6) Cooling step (7) Cleaning step (8) Drying step (9) External additive treatment step Hereinafter, each step will be described.

(1) Production process of resin fine particle A dispersion The resin fine particle A is a resin fine particle that is first added to the reaction system in the aggregation step described later. This step is a polymerization monomer that forms the resin fine particle A. This is a step of forming resin fine particles having a size of about 120 nm by introducing into an aqueous medium and performing polymerization. The resin fine particles A can also be formed by containing a wax. In this case, the wax is contained by dissolving or dispersing the wax in a polymerizable monomer and polymerizing it in an aqueous medium. Resin fine particles are formed.

(2) Production Step of Resin Fine Particle B Dispersion The resin fine particles B are resin fine particles added during the aggregation of the resin fine particles A that were first added to the reaction system in the aggregation step described later. The production method of the resin fine particles B is basically the same as the production method of the resin fine particles A, but the resin fine particles having a value different from the glass transition temperature of the resin fine particles A are formed. According to the preparation method of the resin fine particles B, it is preferable to form resin fine particles having a value higher than the glass transition temperature of the resin fine particles A.

(3) Step of producing colorant fine particle dispersion This is a step of producing a colorant fine particle dispersion having a size of about 110 nm by dispersing a colorant in an aqueous medium.

(4) Aggregation / fusion process of resin fine particles This process is a process of agglomerating resin fine particles and colorant particles in an aqueous medium, and fusing these aggregated particles to obtain particles. This is a step corresponding to the “step of agglomerating resin fine particles”.

  In this step, an alkali metal salt, an alkaline earth metal salt, or the like is added as an aggregating agent to an aqueous medium in which resin fine particles and colorant particles are present, and then the glass transition point of the resin fine particles is higher than the glass transition point. In addition, by heating to a temperature equal to or higher than the melting peak temperature (° C.) of the mixture, the agglomeration proceeds, and at the same time, the resin fine particles are fused.

  In this step, the toner according to the present invention in which spherical toner and non-spherical toner are mixed can be produced by performing particle formation according to the following procedure.

  That is, the resin fine particles A and the colorant particles prepared by the above-described procedure are first added to the reaction system, and an aggregating agent such as magnesium chloride is added to aggregate the resin fine particles A to form particles. Then, during the aggregation of the resin fine particles A, the resin fine particles B having a glass transition temperature different from that of the resin fine particles A added first are added, and further the aggregation of the resin fine particles is continued.

In addition, when the resin fine particles are added, the size of the aggregate composed of the resin fine particles A added first is 30% to 50% of the median diameter (D ₅₀ ) of the final target toner based on the volume. Is preferred.

  When the particle size of the particles reaches a target size, aggregation is stopped by adding a salt such as salt. The addition amount of the resin fine particles B is preferably 2 to 90% by mass with respect to the resin fine particles A.

(5) Ripening step This step is a step of aging until the shape of the particles has a desired average circularity by heat-treating the reaction system subsequent to the aggregation / fusion step.

(6) Cooling step This step is a step of cooling (rapid cooling) the dispersion of the particles. As a cooling treatment condition, cooling is performed at a cooling rate of 1 to 20 ° C./min. The cooling treatment method is not particularly limited, and examples thereof include a method of cooling by introducing a refrigerant from the outside of the reaction vessel, and a method of cooling by directly introducing cold water into the reaction system.

(7) Washing step This step includes a step of solid-liquid separation of the particles from the particle dispersion cooled to a predetermined temperature in the above step, and a surfactant or the like from the particles solid-liquid separated into wet cake-like aggregates. It consists of a cleaning process for removing deposits such as aggregating agents.

  In the washing treatment, the filtrate is washed with water until the electric conductivity of the filtrate reaches 10 μS / cm. Examples of the filtration method include a centrifugal separation method, a vacuum filtration method using Nutsche and the like, and a filtration method using a filter press and the like, and are not particularly limited.

(8) Drying step This step is a step of drying the washed particles to obtain dried particles. Examples of dryers used in this process include spray dryers, vacuum freeze dryers, vacuum dryers, etc., stationary shelf dryers, mobile shelf dryers, fluidized bed dryers, rotary dryers It is preferable to use a stirring dryer or the like.

  The moisture of the dried particles is preferably 5% by mass or less, more preferably 2% by mass or less. In addition, when the dried particles are aggregated with weak interparticle attractive force, the aggregate may be crushed. Here, as the crushing treatment apparatus, a mechanical crushing apparatus such as a jet mill, a Henschel mixer, a coffee mill, or a food processor can be used.

(9) External additive treatment step This step is a step of preparing a toner by mixing the dried particles with an external additive as necessary. As an external additive mixing device, a mechanical mixing device such as a Henschel mixer or a coffee mill can be used.

  Next, the resin, colorant, wax and the like constituting the toner according to the present invention will be described with specific examples.

  First, as a resin that can be used in the toner according to the present invention, a polymer obtained by polymerizing a polymerizable monomer as described below can be used.

  The resin according to the present invention contains a polymer obtained by polymerizing at least one polymerizable monomer as a constituent component. Examples of the polymerizable monomer include styrene, o-methylstyrene, m- Methylstyrene, p-methylstyrene, α-methylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert-butylstyrene, p Styrene or styrene derivatives such as -n-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, methyl methacrylate, ethyl methacrylate, methacryl N-butyl acid, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, Methacrylate derivatives such as n-octyl acrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, methyl acrylate, ethyl acrylate, acrylic Acrylate derivatives such as isopropyl acid, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, phenyl acrylate, Olefins such as ethylene, propylene and isobutylene, vinyl esters such as vinyl propionate, vinyl acetate and vinyl benzoate, vinyl such as vinyl methyl ether and vinyl ethyl ether Vinyl ketones such as ethers, vinyl methyl ketone, vinyl ethyl ketone, vinyl hexyl ketone, N-vinyl compounds such as N-vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidone, vinyl compounds such as vinyl naphthalene, vinyl pyridine, etc. And acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, and acrylamide. These vinyl monomers can be used alone or in combination.

  Moreover, it is also possible to use combining what has an ionic dissociation group as a polymerizable monomer which comprises resin. For example, it has a substituent such as a carboxyl group, a sulfonic acid group, and a phosphoric acid group as a constituent group of the monomer, and specifically includes acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumaric acid. Acid, maleic acid monoalkyl ester, itaconic acid monoalkyl ester, styrene sulfonic acid, allyl sulfosuccinic acid, 2-acrylamido-2-methylpropane sulfonic acid, acid phosphooxyethyl methacrylate, 3-chloro-2-acid phosphooxy And propyl methacrylate.

  Furthermore, polyfunctionality such as divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, neopentyl glycol diacrylate, etc. It is also possible to use a crosslinkable resin by using a functional vinyl.

  Known colorants can be used for the toner according to the present invention. Specific colorants are shown below.

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

  Examples of the colorant for magenta or red 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 colorant 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. And CI Pigment Yellow 138.

  Further, as a colorant for green or cyan, 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 15; 4, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. Pigment blue 62, C.I. I. Pigment blue 66, C.I. I. And CI Pigment Green 7.

  These colorants can be used alone or in combination of two or more as required. The addition amount of the colorant is set in the range of 1 to 30% by mass, preferably 2 to 20% by mass with respect to the whole toner.

  Examples of the wax that can be used in the toner according to the present invention include conventionally known waxes. Specifically, polyolefin waxes such as polyethylene wax and polypropylene wax, long-chain hydrocarbon waxes such as paraffin wax and sazol wax, dialkyl ketone waxes such as distearyl ketone, carnauba wax, montan wax, and trimethylolpropane. Tribehenate, pentaerythritol tetramyristate, pentaerythritol tetrastearate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1,18-octadecanediol distearate, trimellit Esters such as tristearyl acid, distearyl maleate, ethylenediamine dibehenyl amide, trimellitic acid tristearyl amide, etc. Such as amide waxes.

  The melting point of the wax is usually 40 to 160 ° C, preferably 50 to 120 ° C, more preferably 60 to 90 ° C. By setting the melting point within the above range, the heat-resistant storage stability of the toner is ensured, and stable toner image formation can be performed without causing cold offset or the like even when fixing at a low temperature. Further, the wax content in the toner is preferably 1% by mass to 30% by mass, and more preferably 5% by mass to 20% by mass.

  Next, an image forming apparatus capable of forming an image using the toner according to the present invention will be described.

  In the present invention, by using a toner in which a spherical toner and a non-spherical toner having a specific shape are mixed, in the image formation using the spherical toner, the spherical toner does not slip out of the blade and the toner from the image carrier. Can be removed. In particular, an image forming method using a constant temperature fixing toner, which often takes a spherical shape, exhibits good cleaning performance and can fix a toner image having sufficient strength at a fixing temperature lower than that of the prior art. It became like. In addition, since it becomes possible to form a smooth image using the spherical toner, the high-definition image forming performance of the spherical toner can be sufficiently expressed.

  FIG. 2 is a schematic diagram illustrating an example of an image forming apparatus in which the toner according to the present invention can be used.

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

  This image forming apparatus is called a tandem color image forming apparatus, and includes a plurality of sets of image forming units 10Y, 10M, 10C, and 10K, an endless belt-shaped intermediate transfer body unit 7 as a transfer unit, and a recording member P. An endless belt-shaped sheet feeding / conveying means 21 and a heat roll type fixing device 24 as a fixing means. A document image reading device SC is disposed on the upper part of the main body A of the image forming apparatus.

  As one of the different color toner images formed on each photoconductor, an image forming unit 10Y that forms a yellow image includes a drum-shaped photoconductor 1Y as a first photoconductor, and a periphery of the photoconductor 1Y. A charging unit 2Y, an exposure unit 3Y, a developing unit 4Y, a primary transfer roll 5Y as a primary transfer unit, and a cleaning unit 6Y. An image forming unit 10M that forms a magenta image as another different color toner image is disposed around a drum-shaped photoconductor 1M as a first photoconductor, and the photoconductor 1M. A charging unit 2M, an exposure unit 3M, a developing unit 4M, a primary transfer roll 5M as a primary transfer unit, and a cleaning unit 6M. In addition, an image forming unit 10C that forms a cyan image as one of other different color toner images is disposed around the photoconductor 1C as a drum-type photoconductor 1C as a first photoconductor. The charging unit 2C, the exposure unit 3C, the developing unit 4C, the primary transfer roll 5C as the primary transfer unit, and the cleaning unit 6C are provided. Further, an image forming unit 10K that forms a black image as one of other different color toner images is disposed around a drum-shaped photosensitive member 1K as a first photosensitive member, and the photosensitive member 1K. It has a charging means 2K, an exposure means 3K, a developing means 4K, a primary transfer roll 5K as a primary transfer means, and a cleaning means 6K.

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

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

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

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

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

  Further, the housing 8 can be pulled out from the apparatus main body A through the support rails 82L and 82R.

  The housing 8 includes image forming units 10Y, 10M, 10C, and 10K, and an endless belt-shaped intermediate transfer body unit 7.

  The image forming units 10Y, 10M, 10C, and 10K are arranged in tandem in the vertical direction. An endless belt-shaped intermediate transfer body unit 7 is arranged on the left side of the photoreceptors 1Y, 1M, 1C, and 1K in the figure. The endless belt-shaped intermediate transfer body unit 7 includes an endless belt-shaped intermediate transfer body 70 that can be rotated by winding rolls 71, 72, 73, 74, and 76, primary transfer rolls 5Y, 5M, 5C, and 5K, and a cleaning unit. 6A.

  The image forming units 10Y, 10M, 10C, and 10K and the endless belt-shaped intermediate transfer body unit 7 are integrally pulled out from the main body A by the drawer operation of the housing 8.

  In this way, toner images are formed on the photoreceptors 1Y, 1M, 1C, and 1K by charging, exposure, and development, and the toner images of the respective colors are superimposed on the endless belt-shaped intermediate transfer body 70, and are collectively applied to the recording member P. The image is transferred, and fixed by pressing and heating with a heat roll type fixing device 24 and fixed. The photoreceptors 1Y, 1M, 1C, and 1K after transferring the toner image to the recording member P are cleaned with the cleaning device 6A to remove the toner remaining on the photoreceptor, and then the above-described charging, exposure, and development cycle. The next image formation is performed.

  In the present invention, a cleaning blade is used to remove toner remaining on the image carrier (photosensitive member and endless belt-shaped intermediate transfer member).

  Hereinafter, a means for cleaning toner remaining on the photosensitive member without being transferred using an elastic rubber blade as the cleaning blade will be described.

  The contact condition of the elastic rubber blade to the photosensitive member is preferably a contact pressure of 5 to 50 N / m from the viewpoint of improving the cleaning performance. By setting the pressure contact force within the above range, it is difficult for toner to slip through, and it is also difficult to generate blade peeling. There are several methods of pressure contact, such as a method of fixing the blade in advance and fixing the blade, a method of adjusting the load by weight, and a method of using a spring. Is preferred.

  Incidentally, it is preferable to add a static eliminating step for neutralizing the surface of the photoreceptor in order to facilitate cleaning in the previous stage of the cleaning step. This static elimination process is performed by the static eliminator which produces an alternating current corona discharge, for example.

  FIG. 3 is a schematic view showing an example of a cleaning device using a cleaning blade.

In FIG. 3, the electrophotographic photosensitive member is represented by 1, and the blade contact angle is represented by θ. The free length L of the cleaning blade 2 represents the length of the tip of the blade before deformation from the end B of the holder 3 (blade holder) as shown in FIG. h indicates the thickness of the blade. The blade contact angle θ represents an angle formed between the tangent line X at the contact point A of the photoreceptor and the blade before deformation (shown by a dotted line in the drawing). Further, as shown in FIG. 3, the biting amount a is centered on the same central axis C as that of the photosensitive member having a radius r ₀ of the outer periphery S ₀ of the photosensitive member and a position A ′ of the blade (shown by a dotted line in the drawing) before deformation as one point. And the radius r ₁ of the circle S ₁ . A preferable value of the contact angle θ of the cleaning blade to the photosensitive member is θ = 5 to 35 °. Further, the free length L of the cleaning blade represents the length of the tip of the blade before deformation from the end of the support member 191 as shown in FIG. A preferable value of the free length is L = 6 to 15 mm. The thickness of the cleaning blade is preferably 0.5 to 10 mm.

  As the material of the elastic rubber blade, urethane rubber, silicon rubber, fluorine rubber, chloropyrene rubber, butadiene rubber, etc. are known. Of these, urethane rubber has excellent wear characteristics compared to other rubbers. This is particularly preferable. For example, urethane rubber obtained by reacting and curing polycaprolactone ester and polyisocyanate described in JP-A-59-30574 is preferable.

  As described above, the toner according to the present invention is compatible with so-called low-temperature fixing in which a toner image is fixed at a temperature lower than that at present. That is, when the transfer material having the toner image formed with the toner according to the present invention is processed under the condition that the surface temperature of the heating roller is 90 ° C. to 150 ° C., the fold fixing strength is strong and the transfer material is bent. It has a performance that does not cause toner separation from the toner.

  FIG. 4 is a schematic diagram illustrating an example of a fixing device using a heating roller.

  The fixing device 10 shown in FIG. 4 includes a heating roll 71 and a pressure roll 72 in contact with the heating roll 71. In FIG. 4, 90 is a separation claw, and 17 is a toner image formed on a transfer material (transfer paper) P.

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

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

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

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

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

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

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

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

  Moreover, 0.1-30 mm is preferable and, as for the thickness of the coating layer 82 which consists of an elastic body, 0.1-20 mm is more preferable.

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

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

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

  The fixing temperature (the surface temperature of the heating roll 10) is preferably 70 to 180 ° C., and the fixing linear velocity is preferably 80 to 640 mm / sec. The nip width of the heating roll is set to 8 to 40 mm, preferably 11 to 30 mm.

  The separation claw 90 is provided to prevent the transfer material thermally fixed on the heating roll from being wound around the heating roll.

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

  Examples of the present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

1. Preparation of Toners 1 to 6 Toners were prepared as follows.

(1) Preparation of toner 1 (Production of resin fine particles A)
8 parts by mass of sodium dodecyl sulfate and 3000 parts by mass of ion-exchanged water are added to a reaction vessel equipped with a stirrer, temperature sensor, cooling pipe, and nitrogen introduction device, and the internal temperature is increased while stirring at a stirring speed of 230 rpm under a nitrogen stream. The temperature was raised to 80 ° C. After the temperature increase, a polymerization initiator solution prepared by dissolving 10 parts by mass of potassium persulfate in 200 parts by mass of ion-exchanged water was added to adjust the liquid temperature to 80 ° C.

  Next, a polymerizable monomer mixture containing the compound shown below was added dropwise to the reaction vessel over 1 hour, followed by polymerization by heating and stirring at 80 ° C. for 2 hours to prepare resin fine particles. . This is referred to as “resin fine particles (1H)”.

Styrene 480 parts by weight n-butyl acrylate 250 parts by weight Methacrylic acid 68 parts by weight n-octyl-3-mercaptopropionate 16 parts by weight A reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introduction device was charged with polyoxy A solution prepared by dissolving 7 parts by mass of sodium ethylene (2) dodecyl ether sulfate in 800 parts by mass of ion-exchanged water was added. After the reaction vessel is heated to 98 ° C., 260 parts by mass of the “resin fine particles (1H)” and a polymerizable monomer mixture containing the compound shown below are added as they are, and a machine having a circulation path A dispersion liquid containing emulsified particles (oil droplets) was prepared by mixing and dispersing for 1 hour using a type disperser “CLEAMIX (manufactured by M Technique Co., Ltd.)”.

Styrene 245 parts by mass n-butyl acrylate 120 parts by mass n-octyl-3-mercaptopropionate 1.5 parts by mass polyethylene wax (melting point 81 ° C.) 190 parts by mass Next, 6 parts by mass of potassium persulfate was added to this dispersion. A polymerization initiator solution dissolved in 200 parts by mass of ion-exchanged water was added, and polymerization was performed by heating and stirring at 82 ° C. for 1 hour to obtain resin fine particles. This is referred to as “resin fine particles (1HM)”.

  Furthermore, a polymerization initiator solution prepared by dissolving 11 parts by mass of potassium persulfate in 400 parts by mass of ion-exchanged water was added, and a polymerizable monomer solution containing the following compounds at a temperature of 82 ° C. It was added dropwise over 1 hour. After completion of the dropping, polymerization was carried out by heating and stirring for 2 hours, and then cooled to 28 ° C. to obtain resin fine particles. This is designated as “resin fine particles A”. The obtained “resin fine particles A” had a glass transition temperature of 28 ° C.

Styrene 435 parts by weight n-butyl acrylate 130 parts by weight Methacrylic acid 33 parts by weight n-octyl-3-mercaptopropionate 8 parts by weight (Production of resin fine particles B)
While adding 2.3 parts by mass of sodium dodecyl sulfate and 3000 parts by mass of ion-exchanged water to a reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introduction device, stirring at a stirring speed of 230 rpm under a nitrogen stream, The internal temperature was raised to 80 ° C. After raising the temperature, 10 parts by mass of potassium persulfate dissolved in 200 parts by mass of ion-exchanged water is added, the temperature of the solution is again set to 80 ° C., and a polymerizable monomer mixture containing the following compounds is prepared: The solution was added dropwise over 1 hour. After completion of the dropping, polymerization was performed by heating and stirring at 80 ° C. for 2 hours, and then cooled to 28 ° C. to obtain resin fine particles. This is designated as “resin fine particle B”. The obtained “resin fine particle B” had a glass transition temperature of 48 ° C.

Styrene 520 parts by weight n-butyl acrylate 210 parts by weight Methacrylic acid 68 parts by weight n-octyl-3-mercaptopropionate 16 parts by weight (Preparation of colorant dispersion)
90 parts by mass of sodium dodecyl sulfate was added to 1600 parts by mass of ion-exchanged water. While stirring this solution, 420 parts by mass of carbon black (Regal 330R: manufactured by Cabot Corp.) is gradually added, and then dispersed using a stirring device “CLEARMIX (M Technique Co., Ltd.)”. Thus, a dispersion of colorant particles was prepared. This is designated as “colorant dispersion 1”. The particle diameter of the colorant particles in the “colorant dispersion liquid 1” was measured using an electrophoretic light scattering photometer “ELS-800 (manufactured by Otsuka Electronics Co., Ltd.)” and found to be 110 nm.

(Aggregation / fusion process)
The following substances were added to a reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introducing device, and the liquid temperature was adjusted to 30 ° C.

"Resin fine particles A" 300 parts by mass (solid content conversion)
1400 parts by weight of ion-exchanged water 120 parts by weight of “colorant dispersion 1” An aqueous solution in which 3 parts by weight of sodium polyoxyethylene (2) dodecyl ether sulfate is added to 120 parts by weight of ion-exchanged water Next, 5 mol / liter of hydroxylation A sodium aqueous solution was added to adjust the pH to 10, and a 30 ° C. aqueous solution in which 35 parts by mass of magnesium chloride was dissolved in 35 parts by mass of ion-exchanged water was added to the stirred reaction system over 10 minutes. Then, after 3 minutes had elapsed after the addition, the temperature was started to rise, and the temperature of the reaction system was raised to 90 ° C. over 60 minutes to advance the aggregation. The size of the particles formed by aggregation was observed with “Multisizer 3”.

When median diameter (D ₅₀₎ becomes 3.1μm volume-based, added "particulate resin B" 260 parts by mass (in terms of solid content), further aggregation is continued, median diameter (D ₅₀ in volume basis ) Reached 6.5 μm, 750 parts by mass of 20% aqueous sodium chloride solution was added to stop aggregation.

  After adding the 20% sodium chloride aqueous solution, the liquid temperature was set to 98 ° C., and the stirring was continued. While observing the average circularity of the particles with a flow type particle image analyzer “FPIA-2100”, the aggregated resin fine particles were fused. Proceeded. When the average circularity reached 0.965, the liquid temperature was cooled to 30 ° C., hydrochloric acid was added to adjust the pH to 4.0, and stirring was stopped.

(Washing / drying process)
The particles produced in the aggregation / fusion process were solid-liquid separated with a basket type centrifuge “MARK III model number 60 × 40 (manufactured by Matsumoto Kikai Co., Ltd.)” to form a wet cake of particles. The wet cake was washed with ion exchange water at 45 ° C. until the electric conductivity of the filtrate reached 5 μS / cm with the basket-type centrifuge, and then transferred to “flash jet dryer (manufactured by Seishin Enterprise Co., Ltd.)”. Particles were produced by drying until the amount was 0.5% by mass.

(Production of toner)
1% by mass of hydrophobic silica (number average primary particle size = 12 nm) and 0.3% by mass of hydrophobic titania (number average primary particle size = 20 nm) are added to the particles obtained above, and a Henschel mixer is added. To prepare “Toner 1”.

As shown in Table 1, the toner 1 obtained had a volume-based median diameter (D ₅₀ ) of 6.5 μm and an average circularity of 0.965. The median diameter (D ₅₀ ) and the average circularity on a volume basis are values obtained by measurement by the above methods.

(2) Preparation of toner 2 In the preparation process of “toner 1”, “resin fine particle B” was added when the median diameter (D ₅₀ ) on the volume basis of the particles became 1.2 μm by the first aggregation and fusion. Further, aggregation was stopped when the median diameter (D ₅₀ ) on the volume basis reached 2.9 μm. Then, “Toner 2” was prepared by performing the same operation except that the fusion was continued until the average circularity reached 0.980.

(3) Preparation of toner 3 In the preparation process of “toner 1”, “resin fine particle B” was added when the median diameter (D ₅₀ ) on the volume basis of the particles became 3.0 μm by the first aggregation and fusion. Furthermore, aggregation was stopped when the median diameter (D ₅₀ ) on the volume basis reached 7.8 μm. Then, “Toner 3” was produced in the same manner except that the fusion was continued until the average circularity reached 0.938.

(4) Production of Toner 4 In the production process of “Toner 1”, “resin fine particle B” was changed from the first stage of the aggregation / fusion process to form particles. Then, 20% saline is added when the median diameter (D ₅₀ ) on the same volume basis as “toner 1” is reached, and the liquid temperature is cooled to 30 ° C. when the average circularity becomes 0.965. “Toner 4” was produced.

(5) Production of Toner 5 In the production process of “Toner 1”, the addition amount of “resin fine particles A” is 480 parts by mass (in terms of solid content), and the addition amount of “resin fine particles B” is 60 parts by mass ( Particle formation was performed in the same procedure except that the solid content was changed. When the median diameter (D ₅₀ ) on the volume basis of the particles is 6.5 μm, 20% saline is added. At this time, the average circularity is already 0.990, and the average circularity is maintained even if fusion is continued. Did not change. The toner produced by this procedure was designated as “Toner 5”.

(6) Production of Toner 6 In the production process of “Toner 1”, the addition amount of “resin fine particles A” is 130 parts by mass (in terms of solid content), and the addition amount of “resin fine particles B” is 420 parts by mass ( Particle formation was performed in the same procedure except that the solid content was changed. When the median diameter (D ₅₀ ) on the volume basis of the particles was 6.5 μm, 20% saline was added, and when the fusion was continued, the average circularity did not become larger than 0.935. Although the fusion was continued for 3 times as much as the fusion performed with the toner 1, no change was observed in the average circularity. The toner produced by this procedure was designated as “Toner 6”.

Table 1 shows the values of the number%, average circularity, and volume-based median diameter (D ₅₀ ) of the spherical toners and non-spherical toners of “Toners 1 to 6” produced above.

  Each value is a value obtained by measurement by the above method.

2. Evaluation Experiment As an evaluation apparatus, a commercially available composite printer “bizhub Pro C500 (manufactured by Konica Minolta Business Technology Co., Ltd.)” corresponding to the image forming apparatus of FIG. went.

  The surface material and surface temperature of the heating roller mounted on the fixing device of the printer were as follows.

Fixing speed: 230mm / sec
Heat roller surface material: Polytetrafluoroethylene (PTFE)
Heating roller surface temperature: 125 ° C (however, set as follows when evaluating texture fixing strength)
Further, as a cleaning means for removing residual toner on the surface of the photosensitive drum of the printer, a cleaning unit shown in FIG. The cleaning blade was made of urethane rubber, having a free length of 9 mm and a thickness of 2 mm. The contact force of the blade tip to the photosensitive drum was 13.7 N / m.

  In the evaluation, the toner prepared above was loaded in the evaluation device in order, and the following items were evaluated in an environment of normal temperature and normal humidity (20 ° C., 55% RH).

  The print is performed in an environment of normal temperature and humidity (25 ° C., 55% RH), each of a halftone image having an image density of 0.4, a solid white image, a solid black image having an image density of 0.8, and a fine line image. 3000 continuous A4 size print images of / 4 equal parts were made.

<Halftone image evaluation>
The roughness of the halftone image with an image density of 0.4 output on the 3000th print was visually evaluated. Images were evaluated with a maximum of 10 points, and the higher the numerical value, the less rough and the more detailed the image was obtained. A score of 6 or more was considered acceptable.

10 to 9 points: A fine image with no roughness was obtained. 8 to 6 points: A slight feeling of roughness was observed, but no unevenness was observed. 5 points or less: Roughness was noticeable and uneven Occurrence was confirmed.

<Check residual toner>
The surface of the photosensitive drum after continuous printing of 3000 sheets was visually observed with a magnifying glass having a magnification of 10 times, and the presence or absence of residual toner was evaluated. B or higher was accepted.

A: Residual toner was not confirmed. B: Residual toner was slightly observed by magnifying glass, but there was no problem in image evaluation described later. C: The presence of residual toner was confirmed. confirmed.

<Toner slip-through>
The evaluation of the toner slipping was evaluated based on the presence or absence of black streaks on the last three print images of 3000 continuous prints.

<Image dirt>
As the image stain, an image having a reflection density (fogging density) of a white background portion on a printed image prepared after continuous printing of 3000 sheets was less than 0.01 was regarded as acceptable. The reflection density measurement of the white background portion was performed using a reflection densitometer “RD-918 (manufactured by Macbeth)”.

<Fold crease strength>
For the crease fixing strength, the fixing rate of the toner image at the crease on the paper when the surface temperature of the heating roller was 90 ° C., 105 ° C., and 125 ° C. was evaluated. Specifically, when the fixed image of the toner was bent toward the inner surface, the degree of toner peeling at the bent portion was evaluated as the fixing rate.

  The measurement method is to fold the solid image part (image density is 0.8) with the image side inward, rub it with a finger 3 times, open the image, and wipe it 3 times with “JK Wiper (Cresia Co., Ltd.)” The value calculated from the following equation from the image density before and after folding the crease portion of the solid image.

Fixing rate (%) = (image density after folding) / (image density before folding) × 100
From the obtained fixing rate, the crease fixing strength was evaluated as follows, and a value of ◯ or higher was regarded as acceptable.

Evaluation Criteria A: Fixing rate of creases reached 90 to 100% at each temperature O: Fixing rate of folds reached 80 to less than 90% at each temperature X: Fixing rate of folds set to less than 80% was there.

  The results are shown in Table 2.

  As shown in Table 2, in Examples 1 to 3 using the toner corresponding to the toner according to the present invention, all of the above evaluation items were obtained and the effect of the present invention was exhibited. The results shown are obtained. On the other hand, in Comparative Examples 1 to 3 using the toner outside of the present invention, the results obtained in the Examples were not obtained for the above evaluation items, and it was confirmed that the effects of the present invention were not expressed. .

  As can be seen from the results of the above examples, the toner according to the present invention enables smooth cleaning with a blade even when spherical toner remains on an image carrier such as a photoreceptor. High-definition image formation with spherical toner can be performed stably.

  In addition, the toner according to the present invention can provide a high-definition toner image by image formation using a low-temperature fixing compatible toner that is easy to take a spherical shape, and can stably perform environment-friendly image formation with reduced power consumption. It became like.

It is a schematic diagram showing the shape of particles obtained when the toner T according to the present invention is projected by electron microscope photography or the like. 1 is a schematic diagram illustrating an example of an image forming apparatus in which a toner according to the present invention can be used. It is the schematic which shows an example of the cleaning apparatus using a cleaning blade. It is a schematic diagram showing an example of a fixing device using a heating roller.

Explanation of symbols

T Toner L Long axis r Vertical f Toner outer edge p Convex

Claims (11)

In a toner containing at least a resin and a colorant,
The toner is
The median diameter (D ₅₀ ) on a volume basis is 3 μm or more and 8 μm or less,
With respect to the major axis of the toner obtained when the toner is projected,
Toner having a perpendicular with the same length as the major axis is 50% to 70% of the total toner,
The toner having a length that is 0.5 times or more and less than 1.0 times the major axis and that has a perpendicular passing through the convex portion on the outer edge of the toner is 30% or more and 50% or less of the total toner. is there,
Toner characterized by the above. A toner having a length not less than 0.5 times the major axis and less than 1.0 times and having a perpendicular passing through a convex portion on the outer edge of the toner,
The toner according to claim 1, wherein the toner has at least three perpendicular lines that pass through a convex portion on the outer edge of the toner. The toner according to claim 1, wherein an average circularity of the toner is 0.940 or more and 0.980 or less. 4. The toner according to claim 1, wherein a value of a coefficient of variation (CV value) with respect to the median diameter (D ₅₀ ) on the volume basis is 2% or more and 21% or less. 5. The toner according to claim 1, wherein the toner has a glass transition temperature of 10 ° C. or higher and 40 ° C. or lower. The toner according to claim 1, wherein a softening point of the toner is 90 ° C. or more and 120 ° C. or less. The toner is produced through a process of aggregating at least two kinds of resin fine particles,
The step of aggregating the resin fine particles comprises adding resin fine particles having a glass transition temperature different from that of the resin fine particles initially added during the aggregation, and further continuing the aggregation. The toner according to claim 1. The toner according to claim 7, wherein the resin fine particles added during the aggregation have a glass transition temperature higher than that of the resin fine particles added first. A method for producing a toner comprising a step of aggregating resin fine particles,
In the step of aggregating the resin fine particles,
A method for producing a toner, comprising adding resin fine particles having a glass transition temperature different from that of the first added resin fine particles during aggregation, and further continuing the aggregation. The method for producing a toner according to claim 9, wherein the resin fine particles added during the aggregation have a glass transition temperature higher than that of the resin fine particles added first. The timing of adding resin fine particles with a glass transition temperature different from that of the first added resin fine particles
10. The aggregate according to claim 9, wherein the size of the aggregate composed of the resin fine particles added first is 30% to 50% of the median diameter (D ₅₀ ) on the volume basis of the toner. The toner production method according to 10.

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