JP5865683B2 - Capsule toner evaluation method - Google Patents

Description

The present invention relates to a valuation method of the capsule toner to evaluate the coating condition of the core particle surfaces with the resin fine particles are coated.

  An image forming apparatus using an electrophotographic system forms an image made of toner on a recording medium through a charging process, an exposure process, a development process, a transfer process, and a fixing process. In the charging step, the surface of the photoreceptor is uniformly charged by the charging unit. In the exposure step, an electrostatic latent image is formed by irradiating the charged photosensitive member surface with laser light by an exposure device. In the developing step, the electrostatic latent image on the photoconductor is developed by the developing unit, and a toner image is formed on the photoconductor. In the transfer process, the toner image on the photoconductor is transferred onto the recording medium by the transfer unit. In the fixing step, the toner image transferred onto the recording medium is heated by a fixing unit to fix the toner image on the recording medium.

  In order to reduce the energy consumption of the image forming apparatus in the fixing process, development of a low-temperature fixing toner that can be fixed at a relatively low temperature using a binder resin having a low softening point is in progress. However, if a binder resin having a low softening point is used, the storage stability of the toner is lowered and toner aggregation occurs.

  Therefore, for the purpose of improving the storage stability of the toner, a surface modification treatment is performed in which the surface of the core particle is coated with a coating material. By coating the toner base particles to produce a capsule toner, toner aggregation can be suppressed.

  In Patent Document 1, as a method of surface modification treatment, a mechanical stirring force is applied to the powder particles by a rotary stirring means such as a screw, blade, or rotor, whereby the powder particles flow in the powder flow path. A method of spraying a liquid from a spray nozzle onto a powder particle in a fluidized state and coating the surface of the powder particle with a coating material contained in the spray liquid is described. According to the method described in Patent Document 1, the adhesion between the coating material and the powder particles can be increased, and the time required for the surface modification treatment can be shortened.

  Patent Document 2 describes a method of manufacturing a microcapsule in which resin particles and inorganic fine particles are attached to the surface of inner core particles, and the resin particles are dissolved with a solvent to form a coating layer on the surface of the inner core particles. Yes. According to the method described in Patent Document 2, a microcapsule is obtained by forming a coating layer on the surface of the inner core particles by a treatment using a solvent, and then drying and removing the solvent.

Japanese Patent Publication No. 5-10971 JP-A-3-293676

  As described above, a number of methods for producing capsule toners have been filed. However, whether the surface of the core particles can be coated with a coating material, how much the surface of the core particles can be coated, etc. A method for evaluating the covering state of the surface has not been sufficiently established. For example, the covering state is confirmed by performing image analysis on an electron micrograph of the capsule toner. In such an evaluation, it takes time until results are obtained, and the work is complicated, so it cannot be incorporated into the manufacturing process, and can be confirmed in advance to determine the manufacturing conditions, It can only be extracted and confirmed.

An object of the present invention, in the manufacturing process is to provide a valuation method of the capsule toner to evaluate the coating condition of the core particle surface easily and continuously.

The present invention is an evaluation method for evaluating the coating state of the surface of the core particle with the resin fine particles in a capsule toner obtained by coating the surface of the core particle containing a binder resin and a colorant with resin fine particles. And
Based on image data obtained by imaging a plurality of core particles before coating with resin fine particles, an average value of luminance values of a plurality of pixels representing one core particle is calculated as an average luminance, and a plurality of images taken The number-based frequency distribution of the average luminance with respect to the core particles is acquired as the core particle luminance distribution, and one resin fine particle is represented based on image data obtained by imaging a plurality of resin fine particles before coating the core particle. A luminance distribution acquisition step of calculating an average value of luminance values of a plurality of pixels as an average luminance, and acquiring a frequency distribution based on the number of average luminances for the plurality of imaged resin fine particles as a resin fine particle luminance distribution;
In a mixing process in which the core particles and the resin fine particles are mixed in order to coat the surface of the core particles with the resin fine particles, an image obtained by imaging the mixture of the core particles and the resin fine particles Based on the data, the average value of the luminance values of a plurality of pixels representing one core particle with resin fine particles adhering to the surface is calculated as the average luminance, and a plurality of resin fine particles representing one resin fine particle not yet adhered to the core particle are calculated. The average value of the luminance values of the pixels is calculated as the average luminance, the number-based frequency distribution of each average luminance for the entire imaged mixture is acquired as the mixture luminance distribution, and the acquired mixture luminance distribution and the core acquired in advance are acquired. An evaluation system for evaluating the coating state of the surface of the core particle with the resin fine particles by comparing at least one of the particle luminance distribution and the resin fine particle luminance distribution. An evaluation method of a capsule toner; and a-up.

  Further, in the evaluation step, the remaining state of the resin fine particles not yet adhered to the surface of the core particle is evaluated based on the resin fine particle luminance distribution and the mixture luminance distribution, or the core particle The covering state is evaluated by evaluating the generation state of the core particles having the resin fine particles attached to the surface based on the luminance distribution and the mixture luminance distribution.

Further, in the evaluation step, the core particle peak luminance which is an average luminance at which the number frequency peaks in the core particle luminance distribution and the resin fine particle which is an average luminance at which the number frequency peaks in the resin fine particle luminance distribution in the evaluation step. Determine the peak brightness,
In the mixture luminance distribution, a ratio between the number frequency with respect to the core particle peak luminance and the number frequency with respect to the resin fine particle peak luminance is calculated,
The covering state is evaluated using the calculated ratio as an index.

  According to the present invention, in the luminance distribution acquisition step, based on the image data obtained by imaging a plurality of core particles, the number-based frequency distribution of the average luminance for the plurality of core particles imaged is defined as the core particle luminance distribution. Based on the acquired image data obtained by imaging a plurality of resin fine particles, the number-based frequency distribution of the average luminance for the plurality of resin fine particles taken is acquired as the resin fine particle luminance distribution.

  In the evaluation step, based on the image data obtained by imaging the mixture of the core particles and the resin fine particles, the number-based frequency distribution of the average luminance for the imaged mixture is acquired as the mixture luminance distribution, and the acquired mixture Based on the luminance distribution and at least one of the core particle luminance distribution and the resin fine particle luminance distribution acquired in advance, the coating state of the surface of the core particles with the resin fine particles is evaluated.

  In the image data obtained by imaging the core particles, resin fine particles, and core particles with resin fine particles adhering to the surface, pay attention to the luminance of the pixel representing each particle. Utilizing the fact that the frequency distribution is different, it is possible to evaluate the coating state of the surface of the core particle with the resin fine particles.

  Imaging of each particle can be performed continuously using an existing imaging device, etc., so image analysis is performed on the obtained image data, and the covering state is easily evaluated by acquiring the luminance distribution be able to.

  Further, according to the present invention, in the evaluation step, based on the resin fine particle luminance distribution and the mixture luminance distribution, the remaining state of the resin fine particles not yet attached to the surface of the core particle is evaluated, or Based on the core particle luminance distribution and the mixture luminance distribution, the production state of the core particles having the resin fine particles attached to the surface is evaluated.

  For example, since the remaining amount of resin fine particles decreases as the coating of the core particle surface proceeds, the coating state can be evaluated by the remaining state of the resin fine particles. Further, as the coating of the surface of the core particles proceeds, the amount of core particles produced with the resin fine particles adhering to the surface increases, so that the coating state can be evaluated by the state of production of the resin fine particles.

  Further, according to the present invention, in the evaluation step, the core particle peak luminance that is the average luminance at which the number frequency peaks in the core particle luminance distribution, and the average luminance at which the number frequency reaches a peak in the resin fine particle luminance distribution. The resin fine particle peak luminance is determined, and in the mixture luminance distribution, a ratio between the number frequency with respect to the core particle peak luminance and the number frequency with respect to the resin fine particle peak luminance is calculated, and the covering state is calculated using the calculated ratio as an index. To evaluate.

  The peak luminance is the same between the core particle before mixing and the core particle to which the resin fine particles adhere after mixing, and the peak luminance is the same between the resin fine particle before mixing and the resin fine particles not adhering to the core particle after mixing. is there. The peak luminance is determined in advance, and the number frequency with respect to the peak luminance in the mixture luminance distribution changes with the progress of the coating, so the coating depends on the ratio of the number frequency at the peak luminance of each of the core particles and the resin fine particles. The state can be evaluated.

  According to the present invention, in the mixing step of performing a mixing process of mixing the core particles and the resin fine particles in order to cover the surface of the core particles with the resin fine particles, the evaluation method described above may be used for the resin fine particles. The coating state of the surface of the core particle is evaluated, and the mixing process is terminated based on the evaluation result.

  Thereby, since the mixing process can be completed in a desired covering state, a desired covering layer can be formed easily and reliably.

It is a figure which shows distribution of the average brightness | luminance of a core particle. It is a figure which shows distribution of the average luminance of resin fine particles. It is a figure which shows distribution of the average brightness | luminance of a covering core particle. It is a figure for demonstrating that the change of luminance distribution shows the change of the coating state of the core particle surface.

  The present invention is an evaluation method for evaluating a capsule toner coating state obtained by coating the surface of core particles containing a binder resin and a colorant with resin fine particles.

  The evaluation method of the present invention mainly includes (1) a luminance distribution acquisition step and (2) an evaluation step.

(1) Luminance distribution acquisition step In the luminance distribution acquisition step, the core particles and the resin fine particles are photographed, and the distribution of the luminance values of the pixels in the obtained image data is acquired.

  Here, the acquired luminance value distribution is acquired in each of the core particles and the resin fine particles, and more specifically, is an average luminance value distribution in a plurality of core particles, and an average in a plurality of resin fine particles. This is a distribution of luminance values.

First, the average luminance value will be described by taking core particles as an example.
Image data obtained by photographing the core particles is data composed of a plurality of pixels, and a luminance value can be used as a pixel value in each pixel. For example, when the core particle is photographed, the portion of the core particle is bright and the portion other than the core particle appears dark. Using a known image analysis technique, the relatively bright pixel is compared with the pixel representing the core particle. The dark pixel can be separated as a pixel representing other than the core particle.

  In addition, although each pixel depends on the capability of a CCD (photoelectric coupling element) camera used for photographing, each core particle can be represented by a plurality of pixels by making it smaller than one core particle. it can. If the resolution, which is the capability of the CCD element, is increased, the area represented by one pixel becomes smaller and the number of pixels representing one core particle increases.

  In the present invention, one luminance value is measured for each core particle, and a distribution of luminance values in a plurality of core particles is acquired as a luminance distribution. Here, how to measure one luminance value in one core particle is important. As described above, one core particle is represented by a plurality of pixels. However, the surface state of the core particle does not greatly change the luminance value obtained for each pixel even if there are some irregularities. One luminance value in each core particle can be represented by an arithmetic average value (hereinafter simply referred to as “average luminance”). For example, in the image data obtained by photographing, when one core particle is composed of 1000 pixels, the sum of luminance values in 1000 pixels is calculated, and the total sum of the calculated luminance values is 1000 pixels. The average luminance can be calculated by dividing by.

  Since the surface states of the core particles are not the same, the average luminance is slightly different for each core particle. When the average luminance is measured for a plurality of core particles, the average luminance may be distributed. Recognize.

  FIG. 1 is a diagram showing a distribution of average luminance of core particles. The horizontal axis represents the average luminance, and the vertical axis represents the number-based frequency distribution indicating the number frequency. From the luminance distribution shown in FIG. 1, it can be seen that the average luminance of the core particles has a peak at about 70, and those having an average luminance of 90 or more have almost no frequency.

  Next, resin fine particles for coating the surface of the core particles will be described. Resin fine particles can be handled in the same manner as the core particles. That is, resin fine particles are photographed with a CCD camera, and based on the obtained image data, a plurality of pixels representing one resin fine particle are separated from other pixels by image analysis, and a plurality of particles representing one resin fine particle are represented. The average luminance is calculated from the pixels and the average luminance distribution is obtained.

  Since the resin fine particles are smaller than the core particles, the number of pixels representing one resin fine particle is smaller than that of the core particles, but the number of pixels representing one resin fine particle may be at least 10 or more.

  FIG. 2 is a diagram showing a distribution of average luminance of resin fine particles. The horizontal axis indicates the average luminance, and the vertical axis indicates the number frequency. From the luminance distribution shown in FIG. 2, it can be seen that the average luminance of the resin fine particles has a peak at about 100, and those having an average luminance of less than 90 have almost no frequency.

  Here, comparing the luminance distributions of FIG. 1 and FIG. 2, the distribution is completely different between the core particles and the resin fine particles, the core particles are distributed on the low luminance side with the average luminance 90 as a boundary, and the resin fine particles are Distributed on the high luminance side. As described above, the luminance distribution based on the photographed image data is greatly different between the core particle and the resin fine particle. Therefore, the core particle and the resin fine particle can be distinguished using the difference in luminance distribution.

  In order to evaluate the state of core particles whose surfaces are coated with resin fine particles (hereinafter simply referred to as “coated core particles”), it is necessary to verify the luminance distribution of the coated core particles. Prepare coated core particles with the core particle surface coated with resin fine particles in advance and, like the core particles and resin fine particles, perform imaging with CCD, acquire image data, calculate average luminance, and create luminance distribution. The brightness distribution and the brightness distribution of resin fine particles were compared.

  FIG. 3 is a diagram showing a distribution of average luminance of the coated core particles. The horizontal axis indicates the average luminance, and the vertical axis indicates the number frequency. In order to facilitate comparison between the luminance distribution of the core particles and the luminance distribution of the resin fine particles, FIG. 3 also shows the luminance distribution of the core particles and the luminance distribution of the resin fine particles in addition to the luminance distribution of the coated core particles. ing. Graph A shows the average luminance distribution of the core particles, graph B shows the average luminance distribution of the resin fine particles, and graph C shows the average luminance distribution of the coated core particles.

  The average luminance distribution of the coated core particles represented by the graph C and the average luminance distribution of the core particles represented by the graph A are almost the same. This is because the resin fine particles are almost transparent, and in the image data taken by the CCD camera, the luminance value of the pixel representing the coated core particle and the luminance value of the pixel representing the uncoated core particle do not change. is there.

  Here, it is considered that the average luminance distribution does not change between the core particle whose surface is coated with the resin fine particles and the core particle which is not coated. However, since the luminance distribution used in the present invention is a luminance distribution based on the number frequency, the luminance distribution obtained by photographing only the core particles as shown in FIG. 1 and the resin fine particles as shown in FIG. There is a great difference in the distribution between the luminance distribution obtained by photographing only the luminance distribution of the mixture obtained by mixing the resin fine particles and the core particles. Furthermore, since the luminance distribution as a mixture changes as the resin fine particles coat the surface of the core particles, the coating state of the core particle surface with the resin fine particles based on such distribution difference and distribution change. Can be evaluated.

  FIG. 4 is a diagram for explaining that the change in the luminance distribution indicates the change in the covering state of the core particle surface. Similar to FIGS. 1 to 3, the horizontal axis represents the average luminance, and the vertical axis represents the number frequency.

  The luminance distribution of the core particles and the resin fine particles shown in FIGS. 1 and 2 is a luminance distribution of only the core particles as described above, and is a luminance distribution of only the resin fine particles. When the core particle surface is to be coated with the resin fine particles, the core particle surface is covered with the resin fine particles as the time passes by a mixing device, for example, in a mixed state in which the core particles and the resin fine particles are mixed. Will progress.

  Therefore, in the initial mixing state of the mixture of the core particles and the resin fine particles, the core particles and the resin fine particles exist independently, and the resin fine particles are hardly attached to the surface of the core particles.

  In such an initial mixing state, when the luminance distribution is measured based on image data obtained by photographing the mixture, a distribution as shown by a graph D in FIG. 4 is obtained. In the initial mixing state, the number of resin fine particles is larger than that of core particles. Therefore, when the luminance distribution according to the number frequency is measured for the mixture, the distribution of resin fine particles having a large number becomes dominant.

  When the resin fine particles start to adhere to the surface of the core particles by flowing the mixture from such an initial mixing state, the core particles to which the resin fine particles are attached are regarded as one particle, and therefore included in the mixture. The total number of particles will decrease. The particles whose number decreases are all resin fine particles. Regarding the core particles, the number of resin fine particles adhering to the surface increases, but the number of core particles contained in the mixture does not change.

  Therefore, in the luminance distribution of the mixture, when resin fine particles begin to adhere to the surface of the core particles, the distribution corresponding to the resin fine particles starts to decrease, while the distribution corresponding to the core particles starts to increase. Graphs E to H shown in FIG. 4 show changes in the luminance distribution of the mixture. When the time for allowing the mixture to flow becomes long, the coating with the resin fine particles on the surface of the core particles proceeds, and the luminance distribution changes with the progress of the luminance distribution coating.

  The luminance distribution of the mixture changes from the graph E to the graph H in order with the passage of time, that is, the passage of the coating process. At this time, the distribution corresponding to the resin fine particles decreases, and the distribution corresponding to the core particles also increases. When all the resin fine particles adhere to the surface of the core particle, the luminance distribution of the mixture becomes the same as the luminance distribution of only the core particle.

  The luminance distribution of only the core particles, the luminance distribution of only the resin fine particles, and the luminance distribution of the mixture represent the characteristics as described above. By utilizing these characteristics, the coating state of the core particle surface with the resin fine particles is used. Can be evaluated.

First evaluation method Specifically, for example, the luminance distribution of the mixture is acquired at a constant time interval from the initial mixing state, and the change in the distribution corresponding to the core particle in the acquired luminance distribution is observed. Evaluation of the coating state. In the example shown in FIG. 4, since the distribution corresponding to the core particles has a peak at the average luminance 70, the number frequency at the average luminance 70 is obtained at regular intervals, and the number frequency is equal to or higher than a predetermined threshold. Sometimes, it can be evaluated that the surface of the core particle is sufficiently covered with the resin fine particles.

  In addition, the luminance distribution of only the core particles is acquired in advance, and the number frequency of the average luminance that becomes a peak (hereinafter sometimes referred to as “core particle peak luminance”) is determined as the maximum value. When the core particle surface is actually coated with resin fine particles, the number distribution corresponding to the core particle peak luminance in the luminance distribution of only the core particles is obtained in the luminance distribution of the mixture, and the number frequency corresponding to the predetermined maximum number frequency is obtained. When the number frequency of the luminance distribution of the mixture reaches a predetermined ratio, for example, 90% or more, it may be evaluated that the core particle direction is sufficiently covered with the resin fine particles.

Second Evaluation Method Further, not only the distribution corresponding to the core particles but also the distribution corresponding to the resin fine particles may be evaluated in the luminance distribution of the mixture. As described above, in the luminance distribution of the mixture, the distribution corresponding to the core particles increases and the distribution corresponding to the resin fine particles decreases with time. The covering state can also be evaluated using the ratio of the number frequencies of these distributions as one index.

  In the luminance distribution of the mixture, the number frequency in the core particle peak luminance and the number frequency in the resin fine particle peak luminance, which is the peak luminance of the distribution corresponding to the resin fine particles, are obtained at regular intervals, and the ratio of these two number frequencies is obtained. Calculate and use it as an index. When this ratio is equal to or greater than a predetermined threshold value, it can be evaluated that the surface of the core particle is sufficiently covered with the resin fine particles.

Third Evaluation Method Evaluation may be performed by paying attention to the distribution corresponding to the resin fine particles that decrease as the coating progresses, instead of the distribution corresponding to the core particles. In the example shown in FIG. 4, since the distribution corresponding to the resin fine particles has a peak at the average luminance 115, the number frequency at 115, which is the resin fine particle peak luminance, is obtained at regular intervals, and the number frequency is equal to or less than a predetermined threshold. Then, it can be evaluated that the core particle surface is sufficiently covered with the resin fine particles.

  The core particles and the resin fine particles may both be a solid phase (for example, powder or particle), or one may be a solid phase and the other may be a liquid phase (for example, an emulsion or a dispersion). Any of them may be in a liquid phase.

  In addition, in order to acquire the luminance distribution of the average luminance, it is first necessary to acquire the average luminance, but in order to acquire the average luminance, a plurality of pixels representing one particle are formed, and the luminance value of the pixel is determined. Must be measured individually. In the case of core particles, the diameter is on the order of microns, and in the case of resin fine particles, the diameter is on the order of microns to sub-microns. Therefore, it is necessary to measure the luminance value.

  Whether or not the luminance value can be measured depends on the function of the measuring device. For example, the resolution of the measuring device is 0.1 μm (0.1 μm × 0.1 μm) to 0. 4 μm (0.4 μm × 0.4 μm) is preferable.

  By using a flow type particle image analyzer (trade name: FPIA-3000) manufactured by Sysmex as an apparatus capable of photographing core particles and resin fine particles with such a resolution, only core particles, only resin fine particles, and core particles are used. The brightness value can be measured by continuously capturing particle images of each of the mixture of resin and resin fine particles.

  As described above, the present invention can evaluate the coating state of the core particle surface with the resin fine particles based on the luminance distribution acquired based on the obtained image data by photographing the core particles, the resin fine particles and the mixed particles.

  By using the flow type particle image analyzer as described above, it is possible to continuously evaluate the state in which the core particle surface is coated with the resin fine particles, and continuously from the mixing device or the flow device which is a device for coating. The end point of the mixing process can be easily and reliably detected by extracting the particles and evaluating the coating state in parallel with the mixing process.

Moreover, the capsule toner manufactured using the evaluation method of the present invention comprises core particles containing a binder resin and a colorant, and a coating layer covering the surface of the core particles.

  The coating layer is formed on the entire surface or a part of the surface of the core particle, and a coating state in which a part of the resin fine particles constituting the coating layer is fused with at least one of the core particle and the adjacent fine resin particle; It is desirable to become. The minute resin particles are integrated by fusion to form a strong coating layer having high mechanical strength.

  Moreover, since the shape of the resin fine particles remains in the coating layer to some extent, appropriate minute irregularities exist on the surface of the coating layer. This minute unevenness makes it easy for toner to be caught on the cleaning blade, and improves the cleaning performance. When the coating layer is formed on the entire surface of the core particle, by selecting a preferable resin material as the fine resin particle material, aggregation of the capsule toner can be prevented and a capsule toner having excellent temporal stability can be obtained. .

Further, the fluidizing device used in the production method using the evaluation method of the present invention is configured to cause the core particles to flow in the powder flow path by the rotation of the rotating stirring means including the rotating shaft, and to coat the core particles in a fluidized state. The liquid containing the fine resin particles is sprayed from the spraying means to coat the surface of the core particles.

  The peripheral speed at the outermost periphery of the rotary stirring means is preferably 70 m / s or more and 120 m / s or less, and at least a part of the inner wall of the powder channel has an adhesion preventing part for preventing the core particles from adhering to the inner wall of the powder channel. It is preferable to be provided.

  Since the peripheral speed of the rotary stirring means is 30 m / s or more, the core particles and the resin fine particles can flow through the powder flow path at a high speed. In such a flow device, the impact force due to the collision between the core particles and the resin fine particles increases, and a part of the resin fine particles are buried in the core particles. As a result, the contact area between the core particles and the resin fine particles can be increased, and further, by spraying a solvent that can easily evaporate and swell the core particle surface, such as ethanol, The adhesion force with the core particles can be increased, the adhesion force between the core particles and the resin fine particles becomes very large, and the separation of the resin fine particles from the core particles can be reliably prevented.

  Further, by setting the temperature in the apparatus to be equal to or lower than the glass transition temperature of the core particles, the deformation amount of the core particles is small, and the core particles can be coated with the resin fine particles while maintaining the shape of the core particles.

  Thereby, for example, problems such as deterioration of the cleaning property due to the spherical shape of the irregular core particles do not occur. Furthermore, since the resin material used as the core particle and the resin fine particle is not particularly limited, the selection range of the material is expanded.

Hereinafter, a method for producing a capsule toner using the evaluation method will be described in detail.
In the toner manufacturing method, a device for causing the core particles to flow in the powder flow path by the rotation of the rotary stirring means including the rotation shaft is used as the flow device. The rotary stirring means is, for example, a rotor. The peripheral speed at the outermost periphery of the rotor is preferably 70 m / s or more and 120 m / s or less.

The peripheral speed of the outermost periphery of the rotor is a peripheral speed at a portion farthest from the rotation axis of the rotor. The peripheral speed of the outermost periphery of the rotor may be simply referred to as “the peripheral speed of the rotating member”.

  Hereinafter, as an example, the case where both the core particles and the resin fine particles are solid phases (particles) will be described, but the present invention is not limited to this.

  The toner manufacturing method of the present embodiment includes a raw material mixing step, a melt-kneading step, a pulverizing step, a classification step, a resin fine particle preparation step, a spraying step, and a drying step. In the present embodiment, the raw material mixing step, the melt-kneading step, the pulverization step, and the classification step are steps for producing the core particles.

  In such a capsule toner, the surface of the core particles is swollen and softened by a solvent such as lower alcohol sprayed in the spraying process, and a part of the resin fine particles can be embedded in the core particles. Adhesion can be increased.

[Raw material mixing process]
In the raw material mixing step, a binder resin and a colorant, which are raw materials for the core particles, and additives such as a release agent and a charge control agent are mixed.

(A) Binder Resin The binder resin is not particularly limited, and a known binder resin for black toner or color toner can be used. Examples thereof include styrene resins such as polystyrene and styrene-acrylic acid ester copolymer resins, acrylic resins such as polymethyl methacrylate, polyolefin resins such as polyethylene, polyesters, polyurethanes, and epoxy resins. Moreover, you may use resin obtained by mixing a raw material monomer mixture with a mold release agent and performing a polymerization reaction. Binder resin can be used individually by 1 type, or can use 2 or more types together.

  Polyester is excellent in transparency, and can impart good powder fluidity, low-temperature fixability, secondary color reproducibility, and the like to the aggregated particles, and is therefore suitable as a binder resin for color toners. Known polyesters can be used, and examples thereof include polycondensates of polybasic acids and polyhydric alcohols. As the polybasic acid, those known as polyester monomers can be used, for example, terephthalic acid, isophthalic acid, phthalic anhydride, trimellitic anhydride, pyromellitic acid, naphthalenedicarboxylic acid and other aromatic carboxylic acids, maleic anhydride Examples thereof include aliphatic carboxylic acids such as acid, fumaric acid, succinic acid, alkenyl succinic anhydride, and adipic acid, and methyl esterified products of these polybasic acids. A polybasic acid can be used individually by 1 type, or can use 2 or more types together. As the polyhydric alcohol, those known as monomers for polyesters can be used. For example, aliphatic polyhydric alcohols such as ethylene glycol, propylene glycol, butanediol, hexanediol, neopentylglycol, glycerin, cyclohexanediol, cyclohexanediene, etc. Examples thereof include aromatic diols such as alicyclic polyhydric alcohols such as methanol and hydrogenated bisphenol A, ethylene oxide adducts of bisphenol A, and propylene oxide adducts of bisphenol A. A polyhydric alcohol can be used individually by 1 type, or can use 2 or more types together. The polycondensation reaction between the polybasic acid and the polyhydric alcohol can be carried out according to a conventional method. For example, the polybasic acid and the polyhydric alcohol are contacted in the presence or absence of an organic solvent and in the presence of a polycondensation catalyst. The process is terminated when the acid value, softening point, etc. of the polyester to be produced reach a predetermined value. Thereby, polyester is obtained. When a methyl esterified product of a polybasic acid is used as a part of the polybasic acid, a demethanol polycondensation reaction is performed. In this polycondensation reaction, for example, the carboxyl group content at the end of the polyester can be adjusted by appropriately changing the mixing ratio of polybasic acid and polyhydric alcohol, the reaction rate, etc., and thus the properties of the resulting polyester are modified. it can. When trimellitic anhydride is used as the polybasic acid, a modified polyester can also be obtained by easily introducing a carboxyl group into the main chain of the polyester. A self-dispersible polyester in water in which a hydrophilic group such as a carboxyl group or a sulfonic acid group is bonded to the main chain and / or side chain of the polyester can also be used. Further, polyester and acrylic resin may be grafted.

  The binder resin preferably has a glass transition point of 50 ° C or higher and 80 ° C or lower. When the glass transition point of the binder resin is less than 50 ° C., blocking in which the toner thermally aggregates easily occurs in the image forming apparatus, and storage stability may be deteriorated. When the glass transition point of the binder resin exceeds 80 ° C., the fixability of the toner to the recording medium is lowered, and there is a possibility that fixing failure occurs.

(B) Colorant As the colorant, organic dyes, organic pigments, inorganic dyes, inorganic pigments and the like commonly used in the electrophotographic field can be used.

  Examples of the black colorant include carbon black, copper oxide, manganese dioxide, aniline black, activated carbon, nonmagnetic ferrite, magnetic ferrite, and magnetite.

  Examples of yellow colorants include chrome lead, zinc yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow, navel yellow, naphthol yellow S, Hansa yellow G, Hansa yellow 10G, benzidine yellow G, and benzidine. Yellow GR, Quinoline Yellow Lake, Permanent Yellow NCG, Tartrazine Lake, 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, and the like.

  Examples of the orange colorant include red chrome yellow, molybdenum orange, permanent orange GTR, pyrazolone orange, vulcan orange, indanthrene brilliant orange RK, benzidine orange G, indanthrene brilliant orange GK, C.I. I. Pigment orange 31, C.I. I. And CI Pigment Orange 43.

  Examples of red colorants include bengara, cadmium red, red lead, mercury sulfide, cadmium, permanent red 4R, risol red, pyrazolone red, watching red, calcium salt, lake red C, lake red D, and brilliant carmine 6B. Eosin Lake, Rhodamine Lake B, Alizarin Lake, Brilliant Carmine 3B, 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 purple colorants include manganese purple, fast violet B, and methyl violet lake.

  Examples of blue colorants include bitumen, cobalt blue, alkali blue lake, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, phthalocyanine blue partially chlorinated products, first sky blue, induslen blue BC, 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. And CI Pigment Blue 60.

  Examples of the green colorant include chrome green, chromium oxide, pigment green B, micalite green lake, final yellow green G, C.I. I. And CI Pigment Green 7.

  Examples of the white colorant include compounds such as zinc white, titanium oxide, antimony white, and zinc sulfide.

  One colorant can be used alone, or two or more different colorants can be used in combination. Moreover, even if it is the same color, 2 or more types can be used together. The amount of the colorant used is not particularly limited, but is preferably 5 to 20 parts by weight, more preferably 5 to 10 parts by weight with respect to 100 parts by weight of the binder resin.

  The colorant may be used as a master batch in order to uniformly disperse the additive for synthetic resin in the kneaded product. Two or more additives for synthetic resin may be used as composite particles. The composite particles can be produced, for example, by adding an appropriate amount of water, lower alcohol or the like to two or more additives for synthetic resin, granulating with a general granulator such as a high speed mill, and drying.

(C) Charge control agent As the charge control agent, a control agent for positive charge control and negative charge control which are commonly used in the field of electrophotography can be used. Examples of charge control agents for positive charge control include nigrosine dyes, basic dyes, quaternary ammonium salts, quaternary phosphonium salts, aminopyrines, pyrimidine compounds, polynuclear polyamino compounds, aminosilanes, nigrosine dyes and derivatives thereof, triphenylmethane Derivatives, guanidine salts, amidine salts and the like can be mentioned. Charge control agents for controlling negative charges include oil-soluble dyes such as oil black and spiron black, metal-containing azo compounds, azo complex dyes, metal salts of naphthenic acid, metal salts of salicylic acid and its derivatives (metals are metal Chromium, zinc, zirconium, etc.), boron compounds, fatty acid soaps, long-chain alkyl carboxylates, resin acid soaps, and the like. A charge control agent can be used individually by 1 type, or can use 2 or more types together as needed. The use amount of the charge control agent is not particularly limited and can be appropriately selected from a wide range, but is preferably 0.5 to 3 parts by weight with respect to 100 parts by weight of the binder resin.
The charge control agent may be entirely or partially contained in the resin fine particles (coating layer).

(D) Release agent As the release agent, those commonly used in the field of electrophotography can be used, for example, petroleum wax such as paraffin wax and derivatives thereof, microcrystalline wax and derivatives thereof, Fischer-Tropsch wax and derivatives thereof, Polyolefin wax (polyethylene wax, polypropylene wax, etc.) and derivatives thereof, low molecular weight polypropylene wax and derivatives thereof, polyolefin polymer wax (low molecular weight polyethylene wax, etc.) and derivatives thereof, hydrocarbon synthetic wax, carnauba wax and derivatives thereof Derivatives, rice wax and derivatives thereof, candelilla wax and derivatives thereof, plant waxes such as wood wax, animal waxes such as beeswax and spermaceti, fatty acid amides, phenolic fats Examples thereof include oil-based synthetic waxes such as fatty acid esters, long-chain carboxylic acids and derivatives thereof, long-chain alcohols and derivatives thereof, silicone-based polymers, and higher fatty acids. Derivatives include oxides, block copolymers of vinyl monomers and waxes, graft modified products of vinyl monomers and waxes, and the like. The amount of the wax used is not particularly limited and can be appropriately selected from a wide range, but is preferably 0.2 to 20 parts by weight, more preferably 0.5 to 10 parts by weight, particularly preferably 100 parts by weight of the binder resin. 1.0 to 8.0 parts by weight.

  In the raw material mixing step, the core particle raw material including the binder resin, the colorant, and other additives is dry-mixed with a mixer. Known mixers can be used, such as Henschel mixer (trade name, manufactured by Mitsui Mining Co., Ltd.), super mixer (trade name, manufactured by Kawata Co., Ltd.), Mechano Mill (trade name, manufactured by Okada Seiko Co., Ltd.), etc. Henschel type mixing device, ong mill (trade name, manufactured by Hosokawa Micron Corporation), hybridization system (trade name, manufactured by Nara Machinery Co., Ltd.), Cosmo system (trade name, manufactured by Kawasaki Heavy Industries, Ltd.), and the like. When the core particle raw material is mixed in the raw material mixing step, the process proceeds to the melt-kneading step.

[Melting and kneading process]
In the melt-kneading step, the raw material mixture of core particles obtained in the raw material mixing step is melt-kneaded, and the colorant and other additives are dispersed in the binder resin.

  A well-known thing can be used also as a kneading machine, for example, common kneading machines, such as a twin-screw extruder, a 3 roll, a laboratory blast mill, can be used. More specifically, for example, TEM-100B (trade name, manufactured by Toshiba Machine Co., Ltd.), PCM-65 / 87, PCM-30 (all of which are trade names, manufactured by Ikegai Co., Ltd.), etc. Extruder, Needex (trade name, manufactured by Mitsui Mining Co., Ltd.) and other open roll type kneaders. Among these, an open roll type kneader is preferable. When melt-kneading is performed in the melt-kneading process and components such as a colorant are sufficiently dispersed in the binder resin, the process proceeds to the grinding process.

[Crushing process]
In the pulverization step, the melt-kneaded product obtained in the melt-kneading step is cooled to solidify and pulverized. As a pulverizer used for pulverization, a known pulverizer can be used. For example, a jet-type pulverizer that pulverizes using a supersonic jet stream, a rotor (rotor) that rotates at high speed, and a stator (liner). An impact pulverizer that introduces and pulverizes a coarsely pulverized product into the space formed between the two can be used. When the melt-kneaded product is pulverized in the pulverization step, the process proceeds to a classification step.

[Classification process]
In the classification step, fine particles in the pulverized product obtained in the pulverization step are removed to obtain core particles. For classification, a known classifier that removes fine powders by classification by centrifugal force or classification by wind force can be used.

  The core particles obtained through the raw material mixing step, the melt-kneading step, the pulverization step, and the classification step preferably have a volume average particle size of 4 μm to 8 μm.

  When the volume average particle diameter of the core particles is 4 μm or more and 8 μm or less, a high-definition image can be stably formed over a long period of time. Further, by reducing the particle size to this range, a high image density can be obtained even with a small amount of adhesion, and the toner consumption can be reduced. When the volume average particle size of the core particles is less than 4 μm, the particle size of the core particles becomes too small, and there is a possibility that high charge and low fluidity may occur. When this high charging and low fluidization occur, it becomes impossible to stably supply the toner to the photoreceptor, and there is a possibility that background fogging and a decrease in image density may occur. When the volume average particle diameter of the core particles exceeds 8 μm, the particle diameter of the core particles is large, the layer thickness of the formed image is increased, and an image that feels remarkably graininess is obtained, and a high-definition image cannot be obtained. Further, as the particle diameter of the core particle increases, the specific surface area decreases, and the charge amount of the toner decreases. When the charge amount of the toner is small, the toner is not stably supplied to the photoconductor, and there is a possibility that in-machine contamination due to toner scattering occurs.

[Resin fine particle preparation process]
In the resin fine particle preparation step, dried resin fine particles are prepared. Any method may be used as the drying method. For example, dry resin fine particles can be obtained using a method such as hot-air heat receiving drying, conduction heat transfer drying, far-infrared drying, or microwave drying. The resin fine particles are used as a material for coating the core particles in a subsequent coating step. By using the resin fine particles as a coating material on the surface of the core particles, for example, it is possible to prevent the occurrence of aggregation due to melting of low melting point components such as a release agent contained in the core particles during storage.

  The resin fine particles can be obtained, for example, by emulsifying and dispersing a resin, which is a resin fine particle raw material, with a homogenizer or the like. It can also be obtained by polymerization of resin monomer components.

  As the resin used as the resin fine particle raw material, for example, a resin used for a toner material can be used, and examples thereof include polyester, acrylic resin, styrene resin, and styrene-acrylic copolymer. Among the resin exemplified above, the resin fine particles preferably include an acrylic resin and a styrene-acrylic copolymer. Acrylic resins and styrene-acrylic copolymers have many advantages such as light weight and high strength, high transparency, low cost, and easy to obtain materials with uniform particle diameters.

  The resin used as the resin fine particle raw material may be the same type of resin as the binder resin contained in the toner base particles or a different type of resin. Preferably, different types of resins are used. When a different kind of resin is used as the resin fine particle raw material, the softening temperature of the resin used as the resin fine particle raw material is preferably higher than the softening temperature of the binder resin contained in the toner base particles. As a result, the toner manufactured by the manufacturing method of the present embodiment can prevent the toners from fusing together during storage, and can improve storage stability. The softening temperature of the resin used as the resin fine particle raw material is preferably 80 ° C. or higher and 140 ° C. or lower, although it depends on the image forming apparatus in which the toner is used. By using a resin having such a temperature range, a toner having both storage stability and fixing ability can be obtained.

  The resin fine particles are required to have a volume average particle size sufficiently smaller than the average particle size of the toner base particles, and are preferably 0.05 μm or more and 1 μm or less. The volume average particle size of the resin fine particles is more preferably 0.1 μm or more and 0.5 μm or less. When the volume average particle diameter of the resin fine particles is 0.05 μm or more and 1 μm or less, a protrusion having a suitable size is formed on the surface of the coating layer. As a result, the toner manufactured by the manufacturing method of the present embodiment is easily caught by the cleaning blade during cleaning, and the cleaning performance is improved.

[Coating process]
In the coating process, in order to coat the surface of the core particles with the resin fine particles by the flow device, a mixing process of mixing the core particles and the resin fine particles is performed, the resin fine particles are adhered to the surface of the core particles, and the solvent is sprayed. By doing so, the core particles and the resin fine particles are swollen and softened to form a coating layer of the resin fine particles.

  A typical configuration of the flow device is a powder flow path for flowing the core particles and the resin particles, a spray means for spraying the solvent, and a rotation for applying an impact force with the resin fine particles attached to the core particle surfaces. A stirring means, a temperature adjustment jacket for adjusting the temperature in the apparatus, a powder input unit, and a powder recovery unit are configured.

In the manufacturing method using the evaluation method of the present invention, first, while rotating the rotary stirring means, the temperature of the powder flow path and the rotary stirring means is set to a predetermined temperature through a medium through a jacket for temperature adjustment disposed outside them. Adjust to temperature. Thereby, the temperature in the powder channel can be controlled to a temperature at which the core particles and the resin fine particles are not softened and deformed.

  Next, the core particles and the resin fine particles are supplied from the powder charging unit to the powder flow channel in a state where the rotating shaft member of the rotary stirring means rotates. The core particles and resin fine particles supplied to the powder flow path are stirred by the rotary stirring means and flow in the powder flow path in a certain direction. By flowing for a predetermined time, the resin fine particles adhere to the surface of the core particle.

  Here, if the flow time is short, a desired amount of resin fine particles are not coated on the surface of the core particles, so that a coating layer having a desired coverage cannot be formed in the finally obtained capsule toner. If the flow time is long, the resin fine particles are heated during the flow, and aggregation of the resin fine particles or aggregation of the core particles having the resin fine particles attached to the surface occurs.

  Conventionally, as the flow time, the relationship between the coating state of the core particles with the resin fine particles and the flow time has been experimentally acquired in advance, and a desired coating state is obtained based on the acquired relationship. Determine the flow time. When the flow is started, the mixing process is ended by flowing for the determined flow time. During the mixing process, whether or not the coating state is confirmed is confirmed only when the determined time has elapsed.

In the manufacturing method using the evaluation method of the present invention, as described above, the luminance distribution is acquired using an image analysis device such as a flow particle image analysis device, and the mixing process is performed while checking the covering state. be able to. For example, based on the luminance distribution of only the core particles, the number frequency of the peak luminance corresponding to the core particles in the luminance distribution of the mixture of the core particles and the resin fine particles is monitored, and the threshold value (core particle Only 90% or more of the peak number frequency in the luminance distribution), the mixing process is terminated assuming that the surface of the core particles is sufficiently coated. Note that the end of the mixing process does not stop the flow but starts spraying the solvent.
In the state where the surface of the core particle is coated with the resin fine particles, spraying of the solvent is started.

  As the spray solvent, a liquid that can improve the wettability of the resin fine particles to the core particles can be used, and a liquid that does not dissolve the core particles is preferable. Further, since the spray solvent needs to be removed after the coating layer is formed, it is preferably a volatile liquid that easily evaporates.

The spray solvent used in the production method using the evaluation method of the present invention preferably contains a lower alcohol. Examples of the lower alcohol include methanol, ethanol, propanol and the like. When the spray solvent contains such a lower alcohol, the wettability of the resin fine particles to the core particles can be improved, and the resin fine particles can be easily attached to the entire surface or most of the core particles. Moreover, the drying time when removing the spray solvent can be further shortened, and aggregation of the core particles can be suppressed.

  The amount of the resin fine particles is not particularly limited, but is preferably an amount that can cover the entire surface of the core particles. For example, it is preferably used in an amount of 3 to 10 parts by weight with respect to 100 parts by weight of the core particles. If the resin fine particles are less than 3 parts by weight, a sufficient coating layer may not be obtained. When the resin fine particle exceeds 10 parts by weight, the thickness of the coating layer becomes too large, and the fixability may be lowered depending on the constituent materials.

  In the spray treatment, the spray solvent is sprayed onto the core particles having the resin fine particles attached to the surface. The spraying process is continuously performed from the mixing process by the same apparatus as the mixing process.

  The spraying means is a liquid spray that mixes a storage part for storing a spray solvent, a carrier gas storage part for storing a carrier gas, a spray solvent and a carrier gas, and sprays the resulting mixture into the powder flow path. A unit. Compressed air or the like can be used as the carrier gas. Commercially available products can be used as the liquid spray unit. For example, a two-fluid nozzle (trade name: AM6 type, ATTO Co., Ltd.) is passed through a tube pump (trade name: MP-1000A, manufactured by Tokyo Rika Kikai Co., Ltd.). It is possible to use one that is connected to make a fixed amount of liquid.

  Spraying of the spray solvent in the spraying process is performed as follows. First, the spray solvent is sprayed in the state where the core particles with the resin fine particles are flowing in the powder flow path where the temperature is set to be equal to or lower than the glass transition temperature of the core particles, and thermal energy is applied by stirring. As a result, the core particles and the resin fine particles swell and soften. In the present embodiment, the two-fluid nozzle is provided in the powder flow path so as to spray the spray solvent in substantially the same direction as the direction in which the core particles to which the resin fine particles adhere flow. Although the spray angle which is an angle formed by the flow direction and the spray direction of the two-fluid nozzle is not particularly limited, it is preferably 0 ° or more and 80 ° or less. When the spray angle is in such a range, the spray solvent is prevented from unnecessarily adhering to the inner wall of the powder flow path by spraying. Moreover, it is preferable that the spray spreading angle by the two-fluid nozzle is 30 ° or more and 135 ° or less.

  As described above, the peripheral speed of the rotating member is set to at least 30 m / s or more. When the peripheral speed of the rotating member is less than 30 m / s, the flow speed of the core particles is small, and even when the surface of the core particles is softened with the spray solvent, sufficient flow energy is imparted to the core particles. Therefore, the impact force applied by the rotating member is insufficient, and a strong coating layer cannot be formed.

  Further, as described above, the temperature in the powder channel is set to be equal to or lower than the glass transition temperature of the core particles. The temperature in the powder channel is more preferably 30 ° C. or higher and the glass transition temperature of the core particles or lower. When the temperature in the powder flow path exceeds the glass transition temperature of the core particles, the core particles may be too soft when spraying the spray solvent, and the core particles may be aggregated. On the other hand, if the temperature in the powder flow path is lower than 30 ° C., the drying speed of the spray solvent is slowed, and the productivity is lowered.

  The amount of spray solvent used is preferably such that the spray solvent wets the entire surface of the core particles. The amount of spray solvent used is determined by the amount of core particles used. The amount of the spray solvent can be adjusted by the spraying time by the spraying means, the number of spraying, and the like.

  Therefore, the spray amount per unit time by the spraying means is set according to the average particle diameter of the core particles, the usage ratio of the core particles and the resin fine particles, the material of the core particles and the material of the resin fine particles, for example, the entire surface of the core particles Thus, when the resin fine particles are fused and the coating layer is formed, the spraying of the spray solvent by the spraying means may be terminated.

  In the above, as an application example of the evaluation method of the present invention, an example in which the end point of the mixing process before the spraying process is determined is shown, but the present invention is not limited to this. Since the evaluation method of the present invention can be applied not only to a solid phase but also to a liquid phase such as a dispersion, for example, in a state where the core particles are flowing, a spray solvent in which resin fine particles are dispersed is sprayed, The present invention is applicable even when the resin fine particles are adhered simultaneously with wetting the surface of the core particles. In such a case, the spraying of the dispersion liquid can be terminated when the desired coating state is reached based on the luminance distribution.

  The luminance distribution of only the core particles, the luminance distribution of the resin fine particles, and the luminance distribution of the core particles coated with the resin fine particles are the same regardless of the order and state of addition of the particles. In addition, the coating state can be evaluated by the evaluation method of the present invention.

[Drying process]
The spray solvent after forming the coating layer is dried by removing air from a part of the apparatus. For removing the spray solvent, for example, the spray solvent may be vaporized with a dryer. For removing the spray solvent, for example, a commonly used dryer such as a hot-air heat-receiving dryer, a conduction heat-transfer dryer, or a freeze dryer is used.

[External addition process]
An external additive may be further added to the capsule toner on which the coating layer is formed. Examples of the external additive include inorganic fine powders such as silicon dioxide, titanium oxide, aluminum oxide, cerium oxide, zinc oxide, tin oxide, zirconium oxide, polystyrene, acrylic resin, styrene-acrylic resin, polyester, polyolefin, and cellulose. , Resin fine powders such as polyurethane, benzoguanamine, melamine resin, nylon, silicone resin, phenol resin, and vinylidene fluoride. The inorganic fine powder may be surface treated with a hydrophobizing agent such as silicone oil, silane coupling agent, hexamethyldisilazane (HMDS). By using such an external additive, effects such as improvement of fluidity, improvement of triboelectric charging, heat resistance, long-term storage stability, improvement of cleaning characteristics, and control of surface wear characteristics of the photoreceptor can be obtained.

  As the particle diameter of the external additive, the number average particle diameter of the primary particles is preferably 5 nm or more and less than 40 nm. By using the external additive having such a particle size, it is possible to prevent the external additive from being detached from the toner. The external additive is preferably added in an amount of 0.1 to 5 parts by weight with respect to 100 parts by weight of the capsule toner. The external additive is added to the toner using a conventionally known mixer.

As described above, manufacturing method using the evaluation method of the present invention is not limited to the above configuration, and various modifications are possible. For example, in the present embodiment, a case has been described in which the kneaded product obtained by melt kneading is cooled and solidified, and the solidified product is pulverized by a pulverizer and then core particles are obtained by a pulverization method in which particle size adjustment is performed by classification. Without being limited thereto, the core particles may be manufactured according to a general toner manufacturing method. For example, the core particles may be produced by wet methods such as suspension polymerization, emulsion aggregation, dispersion polymerization, dissolution suspension, and melt emulsification.

The capsule toner produced using the evaluation method of the present invention can be used as a one-component developer by itself, but can also be used as a two-component developer by mixing with a carrier. The carrier is not particularly limited, and those commonly used in this field can be used.

The carrier, the magnetic material particles that are coated with a resin is generally used, it is possible to have use it. In addition, other forms of carriers such as particles made of only a magnetic material and resin-dispersed carriers in which magnetic particles are dispersed in resin particles may be used.

  As the resin for coating the carrier surface, known resins can be used. For example, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, acrylic acid ester copolymer, methacrylic acid ester copolymer, silicone Resins, fluorine-containing resins, polyamide resins, ionomer resins, polyphenylene sulfide resins, and mixtures thereof can be used.

  The magnetic material for the carrier core is not particularly limited, and oxides such as ferrite, iron-rich ferrite, magnetite, and γ-iron oxide, metals such as iron, cobalt, and nickel, or alloys thereof can be used. Elements contained in these magnetic materials include iron, cobalt, nickel, aluminum, copper, lead, magnesium, tin, zinc, antimony, beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, vanadium, etc. Is mentioned.

  Although it does not restrict | limit especially as resin used for a resin dispersion type carrier, For example, a styrene acrylic resin, a polyester resin, a fluorine resin, a phenol resin, etc. are mentioned. Both are preferably selected according to the capsule toner used together, and one kind can be used alone or two or more kinds can be used in combination.

The shape of the carrier is preferably a spherical shape or a flat shape. The particle size of the carrier is not particularly limited, but is preferably 10 to 100 μm, more preferably 20 to 50 μm, considering high image quality. Furthermore, the resistivity of the carrier is preferably 10 ⁸ Ω · cm or more, more preferably 10 ¹² Ω · cm or more. The carrier resistivity is determined by placing a carrier in a container having a cross-sectional area of 0.50 cm ² and tapping it, then applying a load of 1 kg / cm ² to the particles packed in the container and placing the load between the load and the bottom electrode. This is a value obtained by reading a current value when a voltage generating an electric field of 1000 V / cm is applied. When the resistivity is low, when a bias voltage is applied to the developing sleeve, charges are injected into the carrier, and carrier particles easily adhere to the photoreceptor. Further, breakdown of the bias voltage is likely to occur.

  The magnetization strength (maximum magnetization) of the carrier is preferably 10 to 60 emu / g, more preferably 15 to 40 emu / g. The magnetization strength depends on the magnetic flux density of the developing roller, but under the general magnetic flux density conditions of the developing roller, if it is less than 10 emu / g, the magnetic binding force does not work and causes carrier scattering. There is a fear. On the other hand, if the magnetization strength exceeds 60 emu / g, it is difficult to maintain a non-contact state with the image carrier in the non-contact development in which the carrier spikes are too high. Further, in the contact development, there is a risk that a sweep is likely to appear in the toner image.

The use ratio of the capsule toner and the carrier in the two-component developer is not particularly limited, and can be appropriately selected according to the kind of the capsule toner and the carrier, but an example is a resin-coated carrier (density 5 to 8 g / cm ² ). The capsule toner may be used so that the capsule toner is contained in the developer in an amount of 2 to 30% by weight, preferably 2 to 20% by weight, based on the total amount of the developer. In the two-component developer, the coverage of the carrier with the capsule toner is preferably 40 to 80%.

(Example)
Examples and Comparative Examples will be specifically described below an example prepared by using the evaluation method of the invention but are not intended to be limited especially. In the following, “parts” and “%” mean “parts by weight” and “% by weight” unless otherwise specified. In the examples and comparative examples, the glass transition temperature of the binder resin and the core particles, the softening temperature of the binder resin, the melting point of the release agent, the volume average particle diameter of the core particles and the particle diameter of the resin fine particles are as follows. It was measured.

[Glass transition temperature of binder resin and core particles]
Using a differential scanning calorimeter (trade name: DSC220, manufactured by Seiko Denshi Kogyo Co., Ltd.), according to Japanese Industrial Standard (JIS) K7121-1987, 1 g of a sample was heated at a heating rate of 10 ° C. per minute and a DSC curve was measured. did. Draw the endothermic peak corresponding to the glass transition of the DSC curve obtained by extending the baseline on the high temperature side to the low temperature side, and the point where the gradient is maximum with respect to the curve from the peak to the peak. The temperature at the intersection with the tangent was determined as the glass transition temperature (Tg).

[Softening temperature of binder resin]
In a flow characteristic evaluation apparatus (trade name: Flow Tester CFT-100C, manufactured by Shimadzu Corporation), a load of 20 kgf / cm ² (9.8 × 10 ⁵ Pa) was applied to give 1 g of a sample (nozzle diameter 1 mm, length). 1 mm), and heated at a heating rate of 6 ° C. per minute. The temperature at which half of the sample flowed out from the die was determined and used as the softening temperature (Tm).

[Melting point of release agent]
Using a differential scanning calorimeter (trade name: DSC220, manufactured by Seiko Denshi Kogyo Co., Ltd.), 1 g of the sample was heated from a temperature of 20 ° C. to 150 ° C. at a heating rate of 10 ° C. per minute, and then rapidly cooled from 150 ° C. to 20 ° C. The operation was repeated twice and the DSC curve was measured. The temperature at the top of the endothermic peak corresponding to the melting of the DSC curve measured in the second operation was determined as the melting point of the release agent.

[Volume average particle diameter of core particles]
20 ml of a sample and 1 ml of sodium alkyl ether sulfate are added to 50 ml of an electrolytic solution (trade name: ISOTON-II, manufactured by Beckman Coulter, Inc.), and ultrasonic waves are applied using an ultrasonic disperser (trade name: UH-50, manufactured by STM). A sample for measurement was prepared by dispersion treatment at a frequency of 20 kHz for 3 minutes. This sample for measurement was measured using a particle size distribution measuring device (trade name: Multisizer 3, manufactured by Beckman Coulter, Inc.) under the conditions of aperture diameter: 20 μm, number of measured particles: 50000 count, and volume particle size distribution of sample particles. From this, the volume average particle size was determined.

[Number average particle diameter of primary particles of resin fine particles]
Measurement was performed using a laser diffraction / scattering particle size distribution measuring apparatus (trade name: Microtrack MT3000, manufactured by Nikkiso Co., Ltd.). In order to prevent aggregation of the measurement sample (resin fine particles), a dispersion in which the measurement sample is dispersed in an aqueous solution of Family Fresh (manufactured by Kao Corporation) is added and stirred, and then injected into the apparatus. Asked. The measurement conditions were: measurement time: 30 seconds, particle refractive index: 1.4, particle shape: non-spherical, solvent: water, solvent refractive index: 1.33. The volume particle size distribution of the measurement sample was measured, and from the measurement results, the particle size at which the cumulative volume from the small particle size side in the cumulative volume distribution was 50% was calculated as the volume average particle size (μm) of the particles.

[Capsule toner manufacturing equipment]
As a capsule toner manufacturing apparatus, a volatile liquid (ethanol) is passed through a hybridization system (trade name: NHS-1 type, manufactured by Nara Machinery Co., Ltd.) through a liquid feed pump (trade name: SP11-12, manufactured by FROM Co., Ltd.). Used was a device provided with a spray unit that was connected to a two-fluid nozzle (trade name: HM-6, manufactured by Fuso Seiki Co., Ltd.). The mounting angle of the two-fluid nozzle was set so that the angle formed between the spray direction of the volatile liquid and the flow direction of the powder was 0 °. In addition, a temperature adjusting jacket was provided on all the walls of the powder flow path. A chiller was used as a temperature adjustment control device for the temperature adjustment jacket. In addition, a gas detector (trade name: XP-3110, manufactured by Shin Cosmos Electric Co., Ltd.) was provided in the gas discharge unit.

[Preparation of resin fine particles]
A polymer obtained by polymerizing styrene and butyl acrylate is freeze-dried, and resin fine particles are styrene-butyl acrylate copolymer fine particles having a volume average particle size of 0.1 μm (glass transition point 72 ° C., softening point 126 ° C.). Got. As a result of measurement by Microtrac (Nikkiso), the primary particle diameter of the shell was 0.12 μm.

  Next, this was dried with a four-fluid spray dryer manufactured by Fujisaki Electric. As a result of measuring the particle diameter of the dried resin fine particles with Microtrac, the volume average particle diameter was 3.1 μm, and the result of moisture measurement by the ket method at 110 ° C. was 0.13%, and sufficient drying was performed. It was.

[Production example of core particles]
[Preparation of core particle 1]
Polyester resin (trade name: Toughton, manufactured by Kao Corporation, glass transition temperature 70 ° C., softening temperature 130 ° C.) 87.5% (100 parts)
・ C. I. Pigment Blue 15: 3 5.0% (5.7 parts)
Paraffin wax (trade name: HNP-10, manufactured by Nippon Seiki Co., Ltd., melting point 70 ° C.)
6.0% (6.9 parts)
・ Organic boron compound (trade name: LR-147, manufactured by Nippon Carlit Co., Ltd.)
1.5% (1.7 parts)

  Each of the above components was premixed with a Henschel mixer (trade name: FM20C, manufactured by Mitsui Mining Co., Ltd.) and then melt-kneaded with a twin-screw extrusion kneader (trade name: PCM65, manufactured by Ikekai Co., Ltd.). This melt-kneaded product is coarsely pulverized with a cutting mill (trade name: VM-16, manufactured by Orient Co., Ltd.), then finely pulverized with a jet mill (manufactured by Hosokawa Micron Co., Ltd.), and further an air classifier (manufactured by Hosokawa Micron Co., Ltd.). The core particle 1 having a volume average particle size of 6.5 μm and a glass transition temperature of 67 ° C. was produced.

[Preparation of core particle 2]
Polyester resin (trade name: Diacron, manufactured by Mitsubishi Rayon Co., Ltd., glass transition point 55 ° C., softening point 130 ° C.) 87.5% (100 parts)
・ C. I. Pigment Blue 15: 3 5.0% (5.7 parts)
Release agent (carnauba wax, melting point 82 ° C.) 6.0% (6.9 parts)
・ Charge control agent (Bontron E84, Orient Chemical Co., Ltd.)
1.5% (1.7 parts)

  Each of the above components was premixed with a Henschel mixer (trade name: FM20C, manufactured by Mitsui Mining Co., Ltd.) and then melt-kneaded with a biaxial extrusion kneader (trade name: PCM30, manufactured by Ikegai Co., Ltd.). This melt-kneaded product is coarsely pulverized with a cutting mill (trade name: VM-16, manufactured by Orient Co., Ltd.), then finely pulverized with a jet mill (manufactured by Hosokawa Micron Co., Ltd.), and further an air classifier (manufactured by Hosokawa Micron Co., Ltd.). To obtain toner mother particles. The toner mother particles had a volume average particle size of 6.5 μm and a glass transition point of 56 ° C.

Example 1
Coating treatment was performed using a hybridization system (trade name: NHS-1 type, manufactured by Nara Machinery Co., Ltd.).

  First, after lowering the internal temperature to 15 ° C. or less, the air supply rate from the rotating shaft is 5 L / min, the air supply rate from the two-fluid nozzle is 5 L / min, and the air supply from the gas discharge unit is With a discharge rate of 10 L / min, a mixture of 100 parts by weight of core particles and 10 parts by weight of resin fine particles is introduced into the hybridization system, and the peripheral speed at the outermost periphery of the rotary stirring unit is 80 m / sec. The resin fine particles were crushed.

  As a result of sampling a small amount and observing with an electron microscope, resin fine particles were adhered to the surface of irregular shaped particles having an average of 6 to 7 μm. In addition, particles considered to be partially spherical shells were also observed.

  Next, ethanol was sprayed at a spray amount of 0.5 mL / min for 15 minutes. Thereafter, the spraying of ethanol was stopped and stirred for 10 minutes, and the rotary stirring unit was stopped. At this time, the supply amount of air from the rotating shaft was 5 L / min, the supply amount of air from the two-fluid nozzle was 5 L / min, and the discharge amount of air from the gas discharge unit was 10 L / min. During the spraying of ethanol, the vapor concentration of ethanol in the gas discharged from the gas discharge unit 222 was stable at about 1.4 vol%.

  At this time, the luminance distribution was measured by FPIA-3000 manufactured by Sysmex Corporation, and the spraying was terminated when the number frequency in the peak luminance of the core particles exceeded the threshold value, whereby Toner 1 was obtained.

  When the surface was observed with an electron microscope, the irregularities of the core particles disappeared on the surface, and the smoothness was maintained. Further, the cross-section of the toner was observed to confirm the film thickness of the coating layer. As a result, the average was 0.34 μm, and the coverage from the cross-section observation (peripheral length of the coated portion / cross-section perimeter) was 87. % Was high.

(Example 2)
Toner 2 was obtained in the same manner as in Example 1 except that the processing speed in the pretreatment was 110 m / s. Moreover, generation | occurrence | production of the coarse powder was not confirmed from the particle size distribution.

  Further, the surface was observed with an electron microscope in the same manner as in the toner 1, and the surface was free of the unevenness due to the core particles, and the smoothness was maintained. Further, when the thickness of the toner 2 was confirmed by cross-sectional observation, the average was 0.23 μm, and the coverage from the cross-sectional observation (peripheral length of the coated portion / cross-sectional peripheral length) was as high as 96%. Met.

(Example 3)
Toner 3 was obtained in the same manner as in Example 1 except that the processing speed in the pretreatment was 45 m / s. Moreover, generation | occurrence | production of the coarse powder was not confirmed from the particle size distribution.

  Further, the surface was observed with an electron microscope, and the unevenness of the core particles disappeared on the surface, and the smoothness was maintained. Furthermore, when the film thickness was confirmed by cross-sectional observation of the capsule toner, the average was 0.45 μm, and the coverage from the cross-sectional observation (peripheral length of the coated portion / cross-sectional peripheral length) was 71%. .

Example 4
A toner 4 was obtained in the same manner as in Example 1 except that the processing time in the pretreatment was eliminated. Moreover, generation | occurrence | production of the coarse powder was not confirmed from the particle size distribution.

  Further, the surface was observed with an electron microscope, and the unevenness of the core particles disappeared on the surface, and the smoothness was maintained. Further, when the film thickness was confirmed by cross-sectional observation, the average was 0.61 μm, and the coverage from the cross-sectional observation (peripheral length of the coated portion / cross-sectional peripheral length) was 67%.

(Example 5)
A toner 5 was obtained in the same manner as in Example 1 except that the core particle 2 was used instead of the core particle 1. Moreover, generation | occurrence | production of the coarse powder was not confirmed from the particle size distribution.

  Further, the surface was observed with an electron microscope, and the surface was found to have smoothness and the unevenness of the core particles disappeared. Further, cross-sectional observation of the toner 5 was conducted to confirm the film thickness. As a result, the average was 0.41 μm, and the coverage from the cross-sectional observation (peripheral length of the coated portion / cross-sectional peripheral length) was 75%. there were.

(Comparative Example 1)
Toner 6 was obtained in the same manner as in Example 1 except that the peripheral speed of the rotating member was 20 m / s. Moreover, generation | occurrence | production of the coarse powder was recognized from the particle size distribution.

  The surface was observed with an electron microscope, and the surface was uneven with many irregularities such as core particles remaining. When the film thickness was confirmed by cross-sectional observation, the average was 0.91 μm, and the coverage from the cross-sectional observation (peripheral length of the coated portion / cross-sectional peripheral length) was 43%.

(Comparative Example 2)
Toner 7 was obtained in the same manner as in Example 1 except that the peripheral speed of the rotating member was 135 m / s. Moreover, generation | occurrence | production of the coarse powder was recognized from the particle size distribution.

  The surface was observed with an electron microscope, and the surface had many irregularities like core particles and was not smooth. Moreover, when the film thickness was confirmed by cross-sectional observation, the average was 1.02 μm, and the coverage from the cross-sectional observation (peripheral length of the coated portion / cross-sectional peripheral length) was 39%.

<Yield>
The yield of capsule toner was determined as follows.
Yield [%] =
(Toner recovery amount [g]) / (Total amount of toner mother particles and resin fine particles [g]) × 100
A: Very good. The calculated toner yield is 95% or more.
○: Good. The calculated toner yield is 90% or more and less than 95%.
Δ: No problem in actual use. The calculated toner yield is 80% or more and less than 90%.
X: Defect. The calculated toner yield is less than 80%.

<Adhesion state>
For Examples 1 to 5 and Comparative Examples 1 and 2, the adhesion state of the capsule toner surface was examined. The capsule toner was sampled and observed using a scanning electron microscope (SEM) at a magnification of 1000 times, and judged visually.

It can be judged that the resin particles are not uniformly aggregated on the surface of the capsule toner but are uniformly dispersed and adhered. The criteria for determining the adhesion state are as follows.
○: There is no aggregate and the toner particles are uniformly attached to the surface.
Δ: Some aggregates are observed.
X: Many aggregates are observed, and the amount of adhesion to the surface of the toner base particles is insufficient.

<Coating uniformity>
Using the toners obtained in Examples 1 to 5 and Comparative Examples 1 and 2, the coating film uniformity, which is the layer thickness uniformity of the shell layer, was evaluated based on the presence or absence of toner aggregates after high-temperature storage. After 20 g of toner was sealed in a plastic container and allowed to stand at 50 ° C. for 48 hours, the toner was taken out and visually confirmed for the presence of aggregates, and then passed through a 230 mesh screen. The weight of the toner remaining on the sieve was measured, and the remaining amount, which is the ratio of this weight to the total toner weight (20 g), was determined and evaluated according to the following criteria. The lower the value of the remaining amount, the more the toner does not block and the better the storage stability, that is, the better the coating uniformity.

The evaluation criteria for coating uniformity are as follows.
○: No aggregates are visually confirmed. The remaining amount is 1% or less.
Δ: Aggregates are not confirmed visually. The remaining amount is more than 1% and less than 3%.
X: A small amount of aggregate is visually confirmed. The remaining amount is 3% or more.

<Membrane strength evaluation>
25 g of a carrier having a diameter of 100 μm and 5 g of capsule toner were placed in a 20 cc glass screw tube and mixed with a shaker at a frequency of 35 Hz for 30 minutes. Thereafter, the debris (a mixture of carrier and toner) was washed and filtered to remove only the carrier. The particle size distribution of the filtrate from which the carrier was removed was measured, and the difference from the initial toner particle size was confirmed.

Compared to the initial toner particle size distribution, the film strength was evaluated by the amount of increased fine particles.
○: Increase rate of fine particles is 5% or less.
(Triangle | delta): The increase rate of microparticles | fine-particles exceeds 5% and is 8% or less.
X: Increase rate of fine particles exceeds 8%.

<Filming properties>
After continuously printing 3000 originals with a printing rate of 5% on A4 size recording paper defined in Japanese Industrial Standard (JIS) P0138, it was visually checked whether the photoreceptor was cloudy. The case where the photoconductor was not fogged was evaluated as ◯ (good, no filming occurred), and the case where the photoconductor was clouded was evaluated as x (defective, filming occurred).

<Cleanability>
After 100,000 sheets of originals with a printing rate of 5% were continuously printed on the A4 size recording paper by the copying machine, a transparent tape (trade name: Mending Tape, Sumitomo 3M) was applied to the surface of the photoreceptor after passing through the cleaning blade. (Made by Co., Ltd.) was peeled off. The transparent tape adhered and peeled to the surface of the photoreceptor was pasted on a white paper, and the density was measured with a spectrocolorimetric densitometer (trade name: X-rite 938, manufactured by SDG Corporation).

  Further, a transparent tape was pasted on a white paper in advance, and the density of the transparent tape portion was also measured with the spectrocolorimetric densitometer. The difference between the density of the portion where the transparent tape pasted and peeled off on the surface of the photoreceptor was pasted on the white paper and the portion where the transparent tape was pasted on the white paper in advance was calculated, and the cleaning property was evaluated from this difference. As for the cleaning property, a difference of 0.005 or less was evaluated as ◯ (good) greater than 0.005 and less than 0.016 as Δ (actually usable) and 0.016 or more as x (unusable).

<Transfer efficiency>
A rectangular solid image portion having a length of 20 mm and a width of 50 mm was formed on an A4 size recording paper by adjusting the toner adhesion amount to 0.6 mg / cm ² . The transfer efficiency was calculated by measuring the weight of the toner on the photoreceptor before transfer and the weight of the toner transferred on the paper surface, respectively, and calculating the transfer efficiency according to the following formula.
Transfer efficiency = (weight of toner transferred onto paper) / (weight of toner on photoconductor before transfer) × 100 (%)

  If the transfer efficiency is 95% or more, ◎ (very good), 90% or more and less than 95%, ◯ (good), 88% or more and less than 90%, △ (actual use possible), less than 88% If there was, it evaluated as x (defect).

<Comprehensive evaluation>
The above evaluation results were combined and comprehensive evaluation was performed according to the following criteria.
A: Very good. There are no items evaluated as Δ and items evaluated as ×.
○: Good. There is no item evaluated as x, and there is one item evaluated as Δ.
Δ: Actual use is possible. There are no items evaluated as x, and there are two or more items evaluated as Δ.
X: Defect. One or more items were evaluated as x or could not be used as toner.
The above evaluation results are shown in Table 1.

As shown in Table 1, toners 1 to 5 which are capsule toners of Examples 1 to 5 which are evaluated by the evaluation method of the present invention and manufactured by the manufacturing method using the evaluation method of the present invention are Comparative Examples 1 and 2. Compared with toners 6 and 7 which are capsule toners of the above, filming property, cleaning property, fluidity and transfer efficiency were excellent. In addition, it was confirmed that the coating state evaluation method of the present invention and characteristics such as film thickness have a very high correlation and are effective formulations.

Claims (3)

In an encapsulated toner obtained by coating the surface of core particles containing a binder resin and a colorant with resin fine particles, an evaluation method for evaluating the covering state of the surface of the core particles with the resin fine particles,
Based on image data obtained by imaging a plurality of core particles before coating with resin fine particles, an average value of luminance values of a plurality of pixels representing one core particle is calculated as an average luminance, and a plurality of images taken The number-based frequency distribution of the average luminance with respect to the core particles is acquired as the core particle luminance distribution, and one resin fine particle is represented based on image data obtained by imaging a plurality of resin fine particles before coating the core particle. A luminance distribution acquisition step of calculating an average value of luminance values of a plurality of pixels as an average luminance, and acquiring a frequency distribution based on the number of average luminances for the plurality of imaged resin fine particles as a resin fine particle luminance distribution;
In a mixing process in which the core particles and the resin fine particles are mixed in order to coat the surface of the core particles with the resin fine particles, an image obtained by imaging the mixture of the core particles and the resin fine particles Based on the data, the average value of the luminance values of a plurality of pixels representing one core particle with resin fine particles adhering to the surface is calculated as the average luminance, and a plurality of resin fine particles representing one resin fine particle not yet adhered to the core particle are calculated. The average value of the luminance values of the pixels is calculated as the average luminance, the number-based frequency distribution of each average luminance for the entire imaged mixture is acquired as the mixture luminance distribution, and the acquired mixture luminance distribution and the core acquired in advance are acquired. An evaluation system for evaluating the coating state of the surface of the core particle with the resin fine particles by comparing at least one of the particle luminance distribution and the resin fine particle luminance distribution. Evaluation of the capsule toner; and a-up.   In the evaluation step, based on the resin fine particle luminance distribution and the mixture luminance distribution, the remaining state of the resin fine particles not yet adhered to the surface of the core particle is evaluated, or the core particle luminance distribution and the mixture are evaluated. 2. The capsule toner evaluation method according to claim 1, wherein the covering state is evaluated by evaluating a generation state of core particles having the resin fine particles attached to a surface based on a luminance distribution. In the evaluation step, a core particle peak luminance that is an average luminance at which the number frequency peaks in the core particle luminance distribution and a resin fine particle peak luminance that is an average luminance at which the number frequency peaks in the resin fine particle luminance distribution are determined. And
In the mixture luminance distribution, a ratio between the number frequency with respect to the core particle peak luminance and the number frequency with respect to the resin fine particle peak luminance is calculated,
2. The capsule toner evaluation method according to claim 1, wherein the covering state is evaluated using the calculated ratio as an index.

Images