JP2008225311A - Toner for electrostatic charge image development - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner for electrostatic charge image development, the toner responding to low temperature fixing, in which organic fine particles exhibiting a sufficient spacer effect and having high durability free from deformation even under stress are externally added. <P>SOLUTION: The toner for electrostatic charge image development contains externally added organic fine particles having the number average particle diameter of from 50 to 200 nm and showing a change rate of the shape factor SF-1 of at most 10% before and after a forced agitation test, and the toner has the glass transition temperature of from 20 to 45°C. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electrostatic image developing toner used for electrophotographic image formation, and more particularly to an electrostatic image developing toner in which organic fine particles are added as an external additive to the toner surface.

  In the industrial world, products that take into consideration the global environment, such as global warming countermeasures, are being actively produced, and in the field of electrophotographic image forming devices, a variety of products that can reduce the environmental burden when creating prints. The technology has been studied. As one of such techniques, there is a technique of a so-called low-temperature fixing compatible electrostatic image developing toner (hereinafter also simply referred to as toner) that can fix a toner image at a lower temperature than before (see, for example, Patent Document 1). ).

  When designing a toner compatible with low-temperature fixing, for example, by selecting a resin having a low glass transition temperature, it is possible to achieve melting and fixing of toner at a low temperature. As a result, the development performance and the like are deteriorated, which hinders good image formation. As a technique for improving the fluidity of the toner, for example, a method of adding inorganic fine particles such as silica or titania called so-called external additives to the surface of the particles constituting the toner can be mentioned.

  However, in a toner using a resin having a low glass transition temperature, the inorganic fine particles are buried in the toner surface due to the difference in surface hardness between the inorganic fine particles and the resin, and stable fluidity may not be imparted. It was. In particular, in a full-color image forming apparatus, a less frequently used toner is agitated in the developing device for a longer time, and if it is a toner compatible with low-temperature fixing, the burying of the external additive is progressed accordingly. This will hinder color image formation.

  As a technique for preventing the burying of the external additive on the toner surface, by adding particles larger than the above-mentioned inorganic fine particles having a size of about 80 to 300 nm to the particle surface constituting the toner, contact between the toners is prevented. Toner has appeared to prevent the burying of external additives. In order to obtain a so-called spacer effect for preventing contact between toners via large particles, a technique using inorganic particles or organic fine particles having a crosslinked structure as large particles has been studied (for example, see Patent Document 2). Among these, in the toner using inorganic particles as the large particles, the specific gravity of the inorganic particles is large, so that when the stress is applied, the large inorganic particles are detached from the toner surface and a sufficient spacer effect cannot be obtained.

On the other hand, in the toner using organic fine particles having a crosslinked structure for large particles, it was not detached from the toner surface even when stress was applied, but the organic fine particles themselves were easily deformed, and the spacer effect was stably maintained. It was difficult. Further, when the organic fine particles provided on the toner surface are deformed, the organic fine particles cover the toner surface and inhibit the exudation of the wax, which causes a new problem that the transfer sheet is difficult to separate from the heating roller in the fixing process. is what happened. As a result, troubles such as separation traces on the transfer sheet and winding around the heating roller occurred.
JP 2005-221933 A JP 2004-163612 A

  An object of the present invention is to provide a toner for developing an electrostatic charge image capable of low-temperature fixing, which is obtained by adding to the surface highly durable organic fine particles that exhibit a sufficient spacer effect and do not deform even under stress. It is the purpose. That is, the toner for developing an electrostatic charge image that can smoothly separate the transfer sheet from the heating roller by eliminating deformation of the external additive due to stress and allowing the wax to smoothly exude from the toner surface during fixing. The purpose is to provide.

  In addition, the present invention prevents the external additive from being deformed so that the oozing of the wax from the toner surface can be performed smoothly, and the transfer sheet is wound around the heating roller even when continuous printing at a low printing rate is performed at low temperature fixing. An object of the present invention is to provide a toner capable of forming a stable image without being attached.

  Furthermore, the present invention prevents deformation of the external additive, so that there is no change in transferability from the start of printing to the end of printing, and image defects such as density unevenness on the halftone image do not occur. An object of the present invention is to provide a toner capable of forming a stable image.

  The present inventor has found that the above-described problems can be solved by the configuration described below.

  The invention according to claim 1 is directed to a toner for developing an electrostatic image, wherein organic particles having a number average particle diameter of 50 nm to 200 nm are externally added to colored particles containing at least a resin and a colorant. When the toner for charge image development has a glass transition temperature of 20 ° C. or higher and 45 ° C. or lower and the organic fine particles are subjected to a forced stirring test, the rate of change of the shape factor SF-1 of the organic fine particles before and after the test is 10 % Or less of the toner for developing electrostatic images. ].

  According to a second aspect of the present invention, the electrostatic image developing toner according to the first aspect is characterized in that the ratio of the organic fine particles deformed by the forced stirring test is 30% by number or less. ].

  According to the toner of the present invention, even if the toner is subjected to stress during image formation, the external additive does not deform or is embedded in the toner surface, and exhibits a stable spacer effect, thereby stabilizing good image formation. Can now be done. That is, since the external additive is not deformed or buried even when the toner is stressed, the wax exudes smoothly from the toner surface during fixing, and the transfer sheet can be separated smoothly from the heating roller. Further, even in a case where the toner stays in the continuous printing or developing device for a long period of time, a stable toner image without density unevenness can be obtained without affecting the transferability of the toner image.

  Furthermore, according to the present invention, even when the toner image is fixed at a lower fixing temperature than the conventional one, the toner image does not peel from the transfer sheet, and the transfer sheet is reliably separated from the fixing roller or the like at the time of fixing, Smooth print creation is now possible.

  The present invention relates to an electrostatic image developing toner obtained by externally adding organic fine particles having a number average particle diameter in a specific range to colored particles containing at least a resin and a colorant.

  The present invention relates to a toner prepared by externally adding organic fine particles having a number average particle size of 50 nm or more and 200 nm or less to colored particles. By specifying the glass transition temperature of the toner and the strength of the organic fine particles, the effect of the present invention is achieved. It is the invention which discovered that is expressed. Also, by setting the glass transition temperature of the toner to 20 ° C. or higher and 45 ° C. or lower, the surface temperature of the heating means constituting the fixing device is set to 90 ° C. to 135 ° C., which is relatively low compared to the conventional fixing process. The toner image can be fixed under the above condition.

  One of the factors hindering stable print production is a phenomenon that inorganic fine particles added as an external additive are buried in the toner surface. When the external additive is buried on the surface of the toner, the surface state of the toner changes. For example, unevenness is likely to occur on the halftone image, and the chargeability of the toner is easily affected. Therefore, it has been studied to add a large-diameter external additive to prevent the external additive from being buried and to prevent the toners from directly contacting each other through the surface. However, the large external additive of inorganic particles is easy to desorb from the toner surface due to its specific gravity, and the organic fine particles are difficult to desorb, but are deformed when subjected to stress and adversely affect the chargeability of the toner. Had the problem of giving.

  The present invention uses organic fine particles having a number average particle size of 50 nm or more and 200 nm or less and hardly deformed even when stressed. It became possible to stably prevent external additives from being buried. At the same time, concealment of the toner particle surface due to deformation of the large-sized organic fine particles is also suppressed, so that the chargeability of the toner is ensured, and it is easy for the wax to ooze out to the toner surface, thereby improving the separation property. Became. In other words, by using organic fine particles whose rate of change of the shape factor SF-1 before and after the forced stirring test is 10% or less, the organic fine particles are not deformed even when subjected to stress, and the burying of the external additive is prevented for a long time. On the other hand, the toner has an excellent effect on the chargeability and separability of the toner.

  Thus, a toner having a glass transition temperature of 20 ° C. or more and 45 ° C. or less, an organic fine particle having a number average particle diameter of 50 nm or more and 200 nm or less, and a change in SF-1 before and after the forced stirring test is 10% or less. It has been found that the above problem can be solved by combining the above.

Hereinafter, the present invention will be described in detail.
1. Glass transition temperature of toner The toner for developing an electrostatic image according to the present invention (hereinafter also simply referred to as “toner”) has a glass transition temperature of 20 ° C. or higher and 45 ° C. or lower. In the present invention, by setting the glass transition temperature of the toner within the above range, for example, the toner image can be fixed at a temperature lower than that of a conventional fixing process of 90 ° C. to 135 ° C.

  A typical method for measuring the glass transition temperature of the toner is measurement using a differential calorimeter (DSC). Specific examples of the differential calorimetric analyzer include “DSC-7 differential scanning calorimeter (manufactured by PerkinElmer)”, “TAC7 / DX thermal analyzer controller (manufactured by PerkinElmer)”, and the like.

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

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

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

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

  In addition, as a method for controlling the glass transition temperature of the toner according to the present invention in a range of 20 ° C. or higher and 45 ° C. or lower, for example, it is realized by controlling factors such as the composition and molecular weight of the resin constituting the toner. Is possible. As a specific method, there is a method of controlling the glass transition temperature by changing the composition ratio of monomers constituting the vinyl copolymer.

Examples of the polymerizable monomer that lowers the glass transition temperature include propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, and the like. In the copolymer resin, the glass transition temperature of the resin can be lowered by increasing the content of these polymerizable monomers.
2. Next, organic fine particles that can be used in the toner according to the present invention will be described.

  The toner according to the present invention is obtained by externally adding organic fine particles having a number average particle diameter of 50 nm or more and 200 nm or less to colored particles containing at least a resin and a colorant. The organic fine particles that can be used in the present invention have a number average particle size of 50 nm to 200 nm, preferably 70 nm to 100 nm.

  By using organic fine particles having a number average particle size in the above range, a so-called spacer effect for avoiding direct contact between toners is appropriately exhibited. As a result, external additives having a small particle diameter added to improve the fluidity and chargeability of the toner such as silica and titania are prevented from being buried in the toner. In addition, by setting the number average particle diameter of the organic fine particles within the above range, the organic fine particles are held on the toner surface even under stress, so that the surface state of the toner is stably maintained.

  In addition, since the organic fine particles are made of the same organic material as the constituent resin of the toner, the surface hardness of the organic fine particles becomes the same level as that of the toner, and the influence of the stress on the toner and the organic fine particles becomes the same level. It is considered that the effect is expressed by becoming (uniform). That is, it is considered that when the toner is stressed, the influence of the stress is not strongly applied only to the external additive, and the external additive is hardly deformed.

  The number average particle diameter of the organic fine particles used in the present invention is specifically measured by the following method. That is, the number average particle size of the organic fine particles is obtained by taking a photograph of the toner with a scanning electron microscope at a magnification of 30,000 times, capturing the photograph image with a scanner, and analyzing the image analysis processing apparatus “LUZEX AP” (Nireco Corporation). ) ”To perform analysis. In the analysis by the image analysis processing device, the organic fine particles present on the toner surface on the photographic image are binarized, the horizontal ferret diameter is calculated for 100 organic fine particles, and the average value is the number average particle diameter. It is said. Specific examples of the scanning electron microscope include a field emission scanning electron microscope “S-4500” manufactured by Hitachi, Ltd.

  The organic fine particles used in the toner according to the present invention have a change rate of the shape factor SF-1 of the organic fine particles before and after the forced agitation test of 10% or less, more preferably 5% or less. It is. Here, the shape factor SF-1 of the organic fine particles is an index indicating the degree of roundness of the organic fine particles, and is defined by the following formula. As described above, the shape factor SF-1 indicates the degree of roundness of the organic fine particles. When the value of SF-1 is 100, the shape of the organic fine particles is a true sphere.

SF-1 = [{(maximum diameter of organic fine particles) ² / (projected area of organic fine particles)} × (π / 4)] × 100
The “maximum diameter” in the formula refers to the width of the organic fine particles that maximizes the interval between the parallel lines when the projected image of the organic fine particles on the plane is sandwiched between two parallel lines. .

  The shape factor SF-1 of the organic fine particles can be calculated using a scanning electron microscope and an image analysis processing device, similarly to the measurement of the number average particle diameter of the organic fine particles. That is, a photograph of the toner is taken with a scanning electron microscope at a magnification of 30,000 times, the photograph image is taken in with a scanner, and is analyzed by an image analysis processing device “LUZEX AP (manufactured by Nireco)”. In the analysis by the image analysis processing device, the organic fine particles existing on the toner surface on the photographic image are binarized, SF-1 is calculated for 100 organic fine particles, and the average value is calculated as the shape factor SF of the organic fine particles. -1. Specific examples of the scanning electron microscope include a field emission scanning electron microscope “S-4500” manufactured by Hitachi, Ltd.

In the present invention, the durability of the organic fine particles is evaluated based on the change rate of the shape factor SF-1 before and after the forced stirring treatment performed in the following procedure. The procedure of the forced agitation test for evaluating the durability of the organic fine particles is as follows. The following forced stirring test was conducted on organic fine particles on cyan toner.
(1) Using the above-described scanning electron microscope and image analysis processing apparatus, 100 organic fine particles were measured with a 30,000 times photograph, and the shape factor SF-1 of the organic fine particles on the cyan toner before forced stirring treatment Measure the average value of.
(2) Clean the cyan toner developing device of the full-color composite image forming apparatus “bizhub Pro C500 type (manufactured by Konica Minolta Business Technologies)” and measure the amount of discharged developer.
(3) The discharged developer is applied to a neutral detergent solution to remove cyan toner, and only the carrier is extracted and dried.
(4) The sample toner is measured so that the carrier and toner concentration is 5%, and the developing device is filled.
(5) A forced stirring test of the developer is performed by printing 1000 sheets under the condition that the toner is not consumed in the full color composite image forming apparatus “bizhub Pro C500 type”.
(6) Using the scanning electron microscope and the image analysis device described above, 100 organic fine particles were measured with a 30,000-fold photograph, and the shape factor SF-1 of the organic fine particles on the cyan toner after forced stirring treatment Measure the average value of.

  According to the above procedure, the shape change of the organic fine particles due to the forced stirring process is measured, and the change rate of the shape factor SF-1 before and after the forced stirring process is calculated. The change rate of the shape factor SF-1 is calculated from the following equation.

Change rate of shape factor SF-1 (%)
= [{(Average value of SF-1 after forced stirring test)-(Average value of SF-1 before forced stirring test)} / (Average value of SF-1 before forced stirring test)] × 100
The rate of change shall be rounded off to the second decimal place.

  For example, when the rate of change of the shape factor SF-1 is 0 before and after forced stirring, the shape of the organic fine particles did not change due to forced stirring, that is, no crushing occurred even when forced stirring was performed. It means that. In the present invention, by using organic fine particles in which the value of the shape factor SF-1 after the processing is 10% or less of the value of SF-1 before the forced stirring processing, the environment is subjected to a lot of stress as in the developing device. Even if it is placed, the spacer effect is exhibited so that the toners do not contact each other on the surface. Further, the toner surface is not hidden by the deformation of the organic fine particles.

  Further, the organic fine particles used in the present invention are preferably those in which the ratio of those deformed by the forced stirring test described above is 30% by number or less in the measurement of 100 organic fine particles. By making the ratio of the deformed organic fine particles 30% or less, the above-mentioned spacer effect is more reliably exhibited, and the problem that the deformed organic fine particles conceal the toner surface and affect the chargeability of the toner is certain. To be avoided. Here, “deformed organic fine particles” refers to particles whose rate of change of organic fine particles before and after the forced agitation test exceeds 10%.

  The reason why the organic fine particles that can be used in the present invention are able to exhibit high durability against crushing and deformation even in an environment where they are subjected to stress for a long time as in a developing device is as follows. The reason is considered as follows. First, it is mentioned that the organic fine particles themselves have a structure that is not easily deformed by having a crosslinked structure. In addition, by lowering the glass transition temperature of the resin constituting the toner, the impact is absorbed when the toner itself is stressed by the softness of the resin, and the external additive on the toner is less likely to be deformed. That is also speculated. Further, it is presumed that the external additive becomes more difficult to deform by setting the specific gravity of the toner base and the external additive to the same level.

  As described above, positively adopting a crosslinked structure in the resin constituting the organic fine particles to obtain organic fine particles having a high degree of crosslinking is an effective means for improving the durability. Specifically, the cross-linking degree indicating the abundance ratio of the cross-linking structure in the organic fine particles is preferably 80% or more, and more preferably 90% or more. The degree of crosslinking of the organic fine particles is measured by the following method and is a value calculated by the following formula.

  First, 0.3 g of dried organic fine particles are weighed as a sample, put into 30 g of toluene, and stirred for 24 hours. After the stirring treatment, the mixture is centrifuged for 5 minutes at 45000 G with a centrifuge, and then the supernatant liquid from which the dissolved product in toluene is extracted is removed. Next, after the undissolved material in toluene is dried with a vacuum dryer, the mass of the undissolved material is measured, and the degree of crosslinking (mass%) is calculated from the following formula.

Degree of crosslinking (mass%) = (mass of toluene undissolved substance (g) /0.3 (g)) × 100
Specific examples of the polymerizable monomer that can be used for forming a crosslinked structure in the resin constituting the organic fine particles include those described later.

  The amount of the organic fine particles added to the toner according to the present invention is preferably 0.3 to 3.0 parts by mass, and more preferably 0.5 to 2.0 parts by mass. By making the amount of organic fine particles added to the toner within the above range, the organic fine particles are arranged and adhered in an appropriately dispersed state on the surface of each toner, and are applied to the image carrier or transfer sheet. It is estimated that the toner can be transferred efficiently.

  Next, the resin material constituting the organic fine particles that can be used as a large-diameter external additive in the present invention will be described. Examples of the resin material constituting the organic fine particles that can be used in the present invention include a styrene polymer resin and a crosslinked resin thereof, a styrene acrylic copolymer resin and a crosslinked resin thereof, a melamine resin, and a benzoguanamine resin. . The organic fine particles can be formed using these resins alone or in a mixture.

Next, the polymerizable monomer constituting the resin will be described with specific examples. The resin may be formed by using only one type of the polymerizable monomers shown below, or may be a resin formed by using a plurality of types of monomers in combination. May be.
(1) Styrene monomer Styrene, α-methylstyrene, β-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, 2,5 -Dimethylstyrene, 3,4-dimethylstyrene, 3,5-dimethylstyrene, 2,4,5-trimethylstyrene, 2,4,6-trimethylstyrene, pn-butylstyrene, pt-butylstyrene, pn-hexyl styrene, pn-octyl styrene, pn-dodecyl styrene, p-methoxy styrene, p-phenyl styrene, etc. Among these, styrene is preferably used.
(2) Acrylic monomers Alkyl acrylates such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-butyl acrylate, n-butyl methacrylate, and alkyl methacrylates Acrylic acid, methacrylic acid, acrylonitrile, acrylamide, etc. Of these, methyl methacrylate is particularly preferable.
(3) Polymerizable monomer capable of forming a crosslinked structure Divinylbenzene, divinyltoluene, ethylene glycol diacrylate, ethylene glycol dimethacrylate, ethylene oxide diacrylate, ethylene oxide dimethacrylate, tetraethylene oxide diacrylate, tetraethylene oxide dimethacrylate 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol diacrylate, neopentyl glycol dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, tetramethylolmethane triacrylate, tetra Methylol methane trimethacrylate, tetramethylol propane acrylate, tetra Methylolpropane methacrylate, tetramethylolpropane tetraacrylate, tetramethylolpropane tetramethacrylate, etc. Among these polymerizable monomers, those having two or more ethylenically unsaturated bonds in the molecule may be used alone. Is possible.

  Next, a method for producing organic fine particles and a method for controlling the number average particle diameter will be described.

  The organic fine particles that can be used in the present invention can be prepared by a known polymerization method. When forming the organic fine particles using the above polymerizable monomer, for example, a known suspension polymerization method or emulsification is used. A production method using a radical polymerization reaction such as a polymerization method is a typical one. In the present invention, organic fine particles having a number average particle diameter of 50 nm to 200 nm are used, and the emulsion polymerization method is said to be a preferable production method for producing organic fine particles having a size in this range. That is, the emulsion polymerization method is preferable because organic particles having a desired size can be produced by controlling the reaction factors listed below.

As a specific method for controlling the number average particle diameter of the organic fine particles,
(1) The surfactant concentration in the aqueous medium is controlled.
(2) Control the amount of polymerization initiator used.
(3) Control the polymerization temperature.
It is possible to produce organic fine particles having a desired number average particle diameter by appropriately combining these conditions.

For example, when producing organic fine particles with a large particle size, the surfactant concentration of the aqueous medium is set as low as possible under the condition of the critical micelle concentration (CMC) or higher, and the polymerization initiator is added in a small amount to perform polymerization. Reaction conditions such as lowering the temperature are set.
3. In addition, in the toner according to the present invention, it is preferable to control the unevenness of the toner surface so that the organic fine particles can stably exist on the toner surface. One of the measures for grasping the unevenness state of the toner surface is the average circularity of the toner. If the average circularity is 0.960 to 0.985, a portion such as a concave portion on the toner surface is used. Even if there is, it is expected that organic fine particles will not collect at such sites. As a result, there is no portion where the organic fine particles are locally unevenly distributed on the toner surface, and a uniform dispersion can be obtained over the entire surface of the toner, and the effect of the present invention can be expressed more significantly. It is done.
4). Next, a toner production method according to the present invention will be described.

  The toner according to the present invention is composed of colored particles containing at least a resin and a colorant. The method for producing the colored particles constituting the toner according to the present invention is not particularly limited, and can be produced by a conventional production method. Specifically, a so-called pulverized toner manufacturing method (pulverization method) in which toner is produced through kneading, pulverization, and classification steps, and a polymerizable monomer is polymerized, and at the same time, particles are formed while controlling the shape and size. And so-called polymerized toner manufacturing methods (for example, emulsion polymerization, suspension polymerization, polyester elongation method, etc.).

  Among them, the toner production by the polymerization method is a small-diameter toner that can form a desired toner while controlling the shape and size of the particles in the production process, and can faithfully reproduce a minute dot image. It is most suitable for making. Among them, the emulsion association method in which resin fine particles of about 120 nm are formed in advance by an emulsion polymerization method or a suspension polymerization method, and particle formation is performed through a process of aggregating the resin fine particles can be said to be one effective production method.

The following is an example of the procedure for producing the toner according to the present invention. The toner according to the present invention is produced through the following steps. That is,
(1) Dissolution / dispersion step in which wax is dissolved or dispersed in a radical polymerizable monomer (2) Polymerization step in which a dispersion of resin particles is produced (3) Aggregation and fusion of resin particles and colorant particles in an aqueous medium Aggregation / fusion process for forming core particles (associate particles) by deposition (4) First aging process for adjusting the shape by aging associated particles with thermal energy (5) For shell in dispersion of core particles Shell forming step of adding colored resin particles and aggregating and fusing the resin particles for the shell onto the core particle surfaces to form colored particles having a core / shell structure. Second aging step of adjusting the shape of the colored particles having the core / shell structure by aging by (7) Cooling the colored particle dispersion of the core / shell structure, and solid-liquid separation of the colored particles from the cooled colored particle dispersion And separated Consists drying step of drying the washing step (8) washing the treated colored particles to remove the surface active agent than the color particles, after drying if necessary,
(9) There may be a case of having an external additive treatment step of adding an external additive to the dried colored particles. The “colored particles” referred to in the above-mentioned steps mean toner base particles, and the toner is used as it is when no external additive treatment is performed.

  When producing the toner according to the present invention, first, resin particles and colorant particles are associated and fused to produce particles serving as a core (hereinafter referred to as core particles). Next, resin particles are added to the core particle dispersion, and the resin particles are aggregated and fused on the surface of the core particles to coat the surface of the core particles to produce colored particles having a core / shell structure. As described above, the toner according to the present invention forms a core / shell structure by adding resin particles to a dispersion of core particles produced by various production methods and fusing the resin particles to the core particles.

  The core portion constituting the toner according to the present invention can be formed through the following steps, for example. That is, the wax component is dissolved or dispersed in the polymerizable monomer that forms the resin. This is mechanically dispersed finely in an aqueous medium, and a polymerizable monomer is polymerized by a miniemulsion polymerization method. In this way, composite resin particles containing the wax component are formed.

  And a core part is formed by carrying out the salting-out / fusing which the composite resin particle and colorant particle which were produced in the said procedure mention later. When the wax component is dissolved in the polymerizable monomer, the wax component may be dissolved and melted or melted and dissolved.

  Hereinafter, each process mentioned above is demonstrated.

(1) Dissolution / dispersion step This step is a step of preparing a radical polymerizable monomer solution in which a wax is mixed by dissolving or dispersing a wax in a radical polymerizable monomer.

(2) Polymerization step In a preferred example of this polymerization step, a radical polymerizable monomer solution in which a wax is dissolved or dispersed in an aqueous medium containing a surfactant having a critical micelle concentration (CMC) or less is used. Addition, mechanical energy is applied to form droplets, and then a water-soluble radical polymerization initiator is added to advance the polymerization reaction in the droplets. The droplets may contain an oil-soluble radical polymerization initiator. In such a polymerization step, it is indispensable to forcibly emulsify (form droplets) by applying mechanical energy. Examples of means for imparting such mechanical energy include means for imparting strong stirring action such as homomixer, ultrasonic wave, and Manton gorin and ultrasonic vibration.

  By this polymerization step, resin particles (also referred to as composite resin particles) containing a wax and a binder resin are obtained. Such resin particles may be colored particles or non-colored particles. Colored resin particles can be obtained by polymerizing a monomer composition containing a colorant. In the case of resin particles that are not colored, the resin particles are colored by fusing the resin particles and the colorant particles by adding a dispersion of the colorant particles to the resin particle dispersion in the aggregation / fusion process described below. Particles are obtained.

  The weight average particle size (dispersed particle size) of the resin particles obtained in the polymerization step is preferably in the range of 10 to 1000 nm, more preferably in the range of 30 to 300 nm. The weight average particle diameter is a value measured using an electrophoretic light scattering photometer “ELS-800 (manufactured by Otsuka Electronics Co., Ltd.)”.

(3) Aggregation / fusion process The aggregation / fusion process is a process of forming core particles (association particles) by associating resin particles obtained in the polymerization process. A typical method for agglomerating and fusing the resin particles is a salting-out / fusing method. In addition, in the aggregation / fusion process, it is possible to aggregate and fuse internal additive particles such as wax particles and charge control agents together with resin particles and colorant particles.

  Here, “salting out / fusion” is to stop the particle growth by adding the aggregation terminator when the particles are aggregated and fused in parallel and grown to a desired particle size.

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

  Colorant particles can be prepared by dispersing a colorant in an aqueous medium. The dispersion treatment of the colorant is performed in a state where the surfactant concentration is set to a critical micelle concentration (CMC) or more in water. Although the disperser used for the dispersion | distribution process of a coloring agent is not specifically limited, For example, the following are mentioned. That is, a pressure disperser such as an ultrasonic disperser, a mechanical homogenizer, a manton gourin or a pressure homogenizer, a media grinder such as a sand grinder, a Getzman mill, or a diamond fine mill.

  Further, as the usable surfactant, the same surfactants as those described above can be used. The colorant (particles) may be surface-modified. In the surface modification method of the colorant, the colorant is dispersed in a solvent, the surface modifier is added to the dispersion, and the system is reacted by raising the temperature. After completion of the reaction, the colorant is filtered off, washed and filtered with the same solvent, and dried to obtain a colorant (pigment) treated with the surface modifier.

  The salting out / fusion method, which is a representative example of the method for aggregating and fusing the resin particles, comprises the following steps. First, in a water-based medium in which resin particles and colorant particles are present, a salting-out agent composed of an alkali metal salt, an alkaline earth metal salt, a trivalent salt, or the like is used as a flocculant, and the water content exceeds a critical coagulation concentration. Add amount. Next, salting is advanced by heating to a temperature above the glass transition point of the resin particles and above the melting peak temperature of the mixture, and at the same time, the particles are fused. Alkali metal salts and alkaline earth metal salts which are salting-out agents include lithium, potassium, sodium and the like as alkali metals, and examples of alkaline earth metals include magnesium, calcium, strontium and barium, preferably Examples include potassium, sodium, magnesium, calcium, and barium.

  When agglomeration and fusion are performed by the salting-out / fusion method, it is preferable to shorten the time after addition of the salting-out agent as much as possible. This is because there is a concern that the passage of time after salting out may affect the state of particle aggregation, the particle size distribution, and the surface performance of the toner. In addition, the temperature at which the salting-out agent is added must be at least the glass transition temperature of the resin particles. This is because if the temperature at which the salting-out agent is added is equal to or higher than the glass transition temperature of the resin particles, although the salting-out / fusion of the resin particles proceeds quickly, it becomes difficult to control the particle size. This is because the formation of particles is a concern. The temperature range when adding the salting-out agent may be equal to or lower than the glass transition temperature of the resin, but is generally 5 to 55 ° C, preferably 10 to 45 ° C.

  In addition, after adding the salting-out agent below the glass transition temperature of the resin particles, the temperature is raised as quickly as possible so that it is above the glass transition temperature of the resin particles and above the melting peak temperature of the mixture. Heat. The time until this temperature rise is preferably less than 1 hour. Furthermore, it is necessary to quickly raise the temperature, and the rate of temperature rise is preferably 0.25 ° C./min or more. The upper limit of the rate of temperature rise is not particularly clear, but if the temperature is increased instantaneously, salting out proceeds rapidly, and particle size control becomes difficult, so 5 ° C./min or less is preferable. In this way, a dispersion liquid of associated particles (core particles) formed by subjecting arbitrary particles such as resin particles and a colorant to salting out / fusion is obtained through the aggregation / fusion process.

(4) First aging step This step is a step of adjusting the shape of the particles by aging the associated particles by supplying thermal energy to the dispersion liquid of the associated particles formed in the above-described aggregation / fusion step. It is.

  In the present invention, the shape of the core particles can be controlled by controlling the heating temperature and time in the first aging process in addition to the control of the heating temperature in the aggregation / fusion process. By performing such aging, the particle size of the core particles can be kept constant and the particle size distribution can be controlled within a narrow range. In addition, the surface of the formed core particles can be smoothed, and at the same time, the shape can be controlled to be uniform. Specifically, by lowering the heating temperature in the agglomeration / fusion process and suppressing the progress of fusion between the resin particles, the uniformization of the particle size is promoted, and the heating temperature is lowered in the first aging process. And it controls so that time may be lengthened and the shape of a core particle may be equalized.

(5) Shelling step The shelling step is performed by adding the resin particle dispersion for the shell to the core particle dispersion, and aggregating and fusing the shell resin particles on the core particle surface. Is a step of forming colored particles having a core-shell structure in which a shell is coated with a shell.

  Specifically, the temperature of the core particle dispersion is maintained at the same temperature as the above-described aggregation / fusion step and the first aging step, and the dispersion of the resin particles for shells is added in this state. Then, colored particles are formed by slowly covering the core particle surfaces with the resin particles for shells over several hours while continuing the heating and stirring. The heating and stirring time is preferably 1 hour to 7 hours, particularly preferably 3 hours to 5 hours.

  By performing such an operation, a shell having a thickness of 100 to 300 nm is formed on the surface of the core particle in the shelling step. And particle growth is stopped by adding stop agents, such as sodium chloride, in the stage in which colored particles became a predetermined particle size.

(6) Second ripening step In this step, after the colored particles have reached a predetermined particle size by shelling, a stopper is added to stop particle growth, and then the dispersion of the colored agent particles is heated and stirred. Is a process that continues for several hours. In the second aging step, by continuing the heating and stirring, the fusion of the resin particles for the shell adhered to the surface of the core particles is advanced, and the adhesion of the resin particles for the shell to the surface of the core particles is strengthened. . At the same time, the colored particles after the shell formation are rounded and have a uniform shape.

  In the present invention, it is possible to control the shape of the colored particles in the true sphere direction by setting the time of the second aging step longer or by setting the aging temperature higher.

(7) Washing process In this process, the colored particle dispersion liquid having the core / shell structure that has undergone the second aging process is cooled, and the colored particles are subjected to solid-liquid separation treatment from the cooled colored particle dispersion liquid, thereby being separated. This is a step of washing the colored particles in order to remove the surfactant and the like from the particles.

  First, the core-shell structured colored particle dispersion is rapidly cooled. The cooling process condition is cooling at a cooling rate of 1 to 20 ° C./min. The specific cooling treatment method is not particularly limited, for example, a method of cooling the colorant dispersion by supplying a refrigerant from the outside of the reaction vessel, a method of cooling by directly introducing cold water into the reaction system, etc. Is mentioned.

  Next, the colored particles are subjected to solid-liquid separation from the dispersion of colored particles cooled to a predetermined temperature by the cooling treatment (solid-liquid separation treatment). The colored particles in the wet state separated by the solid-liquid separation process take the form of an aggregate aggregated in a cake form called a toner cake. Further, a cleaning process is performed to remove deposits such as surfactants and salting-out agents from the surface of the colored particles taking the form of a toner cake. Examples of the solid-liquid separation process include a centrifugal separation method, a vacuum filtration method using Nutsche and the like, and a filtration method using a filter press and the like.

  In order to reliably remove the deposits from the surface of the colored particles, it is also preferable to repeat the solid-liquid separation process and the cleaning process.

(8) Drying step This step is a step of obtaining dried colored particles by drying the toner cake prepared by the solid-liquid separation process after the final washing process. Examples of the drying apparatus that can be used in this step include a spray dryer, a vacuum freeze dryer, a vacuum dryer, and the like, and a stationary shelf dryer, a movable shelf dryer, a fluidized bed dryer, a rotary type dryer, and the like. It is preferable to use a dryer, a stirring dryer, or the like. The water content of the colored particles after the drying treatment is preferably 5% by mass or less, and more preferably mass% or less. In addition, although the dried colored particles may aggregate due to weak interparticle attractive force, in such a case, the aggregate may be crushed. Examples of the crushing treatment apparatus include mechanical crushing apparatuses such as a jet mill, a Henschel mixer, a coffee mill, and a food processor.

  Through the above steps, colored particles constituting the toner according to the present invention can be produced. In addition, when it is not necessary to add an external additive to be described later, the colored particles that have been dried are used as a toner.

(9) External Addition Treatment Step This step is a step of adding and mixing an external additive to the colored particles that have been dried, if necessary. Examples of apparatuses that can be used for the external addition treatment include mechanical mixing apparatuses such as a Henschel mixer and a coffee mill.

  Further, the toner according to the present invention can be produced by a pulverization method, and examples of the toner production method by the pulverization method include those according to the following procedure.

  In the toner production by the pulverization method, first, toner components such as a binder resin, a charge control agent, and a colorant are mixed using a Henschel mixer, and then the mixture is put into a kneader such as a twin screw extruder kneader. And kneading (kneading step).

  The kneaded product is cooled and then loosely pulverized with a feather mill, a hammer mill or the like, and further finely pulverized with a mechanical pulverizer such as a kryptron or an airflow pulverizer such as a jet mill (pulverization step).

  Next, the finely pulverized product is put into a mechanical or airflow classifier and subjected to a classification process to obtain particles having a desired particle size (classification step). Classification by a classifier is performed by utilizing the balance between the wind force that conveys the toner and the centrifugal force and centripetal force applied to the toner during conveyance, or by utilizing the property of the air current called the Coanda effect.

  Furthermore, the circularity of the particles is controlled by heat-treating the particles produced through the above steps. As a device for controlling the circularity, for example, a “Saffusion system (manufactured by NPK)” or the like that controls the circularity by bringing hot air into contact with particles is representative.

Then, an external additive such as the aforementioned organic fine particles is added to the particles produced through the above procedure to produce a toner. Examples of the apparatus for performing the external additive treatment include a mechanical mixing apparatus such as a Henschel mixer and a coffee mill.
5. Constituent Elements of Toner Next, toner constituent elements that can be used in the toner according to the present invention, such as resins, colorants, waxes, and external additives and lubricants other than the organic fine particles described above will be described with specific examples. To do.

  First, resins that can be used in the toner according to the present invention will be described. The resin that can be used in the toner according to the present invention is not particularly limited as long as the glass transition temperature of the toner can be within a range of 20 ° C. or higher and 45 ° C. or lower.

The resin that can be used in the toner according to the present invention is prepared by polymerizing a polymerizable monomer typified by a vinyl monomer as shown in (1) to (10) below, and has a glass transition temperature. Is a polymer in the range of 20 ° C. or higher and 45 ° C. or lower. That is, examples of the resin that can be used in the toner according to the present invention include those obtained by polymerizing the following vinyl monomers alone or in combination.
(1) Styrene or styrene derivatives Styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene, α-methyl styrene, p-chloro styrene, 3,4-dichloro styrene, p-phenyl styrene, p-ethyl styrene 2,4-dimethylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, etc. (2) Methacrylic acid ester derivatives Methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate , Lauric methacrylate (3) Acrylic acid ester derivatives Methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, acrylic acid, etc. Isobutyl, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, phenyl acrylate, and the like.
(4) Olefins Ethylene, propylene, isobutylene, etc. (5) Vinyl esters Vinyl propionate, vinyl acetate, vinyl benzoate, etc. (6) Vinyl ethers Vinyl methyl ether, vinyl ethyl ether, etc. (7) Vinyl ketones Vinyl methyl ketone, Vinyl ethyl ketone, vinyl hexyl ketone, etc. (8) N-vinyl compounds N-vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidone, etc. (9) Vinyl compounds Vinyl naphthalene, vinyl pyridine, etc. (10) Acrylic acid or methacrylic acid Derivatives Acrylonitrile, methacrylonitrile, acrylamide, etc.

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

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

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

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

  Divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, neopentyl glycol diacrylate, and the like.

  Next, examples of the colorant that can be used in the toner according to the present invention include the following known colorants.

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

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

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

  Further, as a colorant for green or cyan, C.I. I. Pigment blue 15, C.I. I. Pigment blue 15; 2, C.I. I. Pigment blue 15; 3, C.I. I. Pigment blue 15; 4, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. Pigment blue 62, C.I. I. Pigment blue 66, C.I. I. And CI Pigment Green 7.

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

Next, the wax that can be used for the toner according to the present invention will be described. Examples of the wax that can be used in the toner according to the present invention include conventionally known waxes, and specific examples include the following.
(1) Long-chain hydrocarbon wax Polyolefin wax such as polyethylene wax and polypropylene wax, paraffin wax, sazole wax, etc. (2) Ester wax Trimethylolpropane tribehenate, pentaerythritol tetramyristate, pentaerythritol tetrasteare Rate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1,18-octadecanediol distearate, tristearyl trimellitic acid, distearyl maleate, etc. (3) Amide wax Ethylenediamine dibehenyl amide, trimellitic acid tristearyl amide, etc. (4) Dialkyl ketone waxes, distearyl ketone, etc. (5) Others Carnaubawack , Montan waxes, and the like.

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

  Next, the toner according to the present invention is preferably prepared by adding, as an external additive (= external additive), one represented by the following inorganic fine particles in addition to the organic fine particles described above. That is, the addition of the external additive improves the fluidity and chargeability of the toner, and improves the cleaning property. The type of external additive is not particularly limited, and examples thereof include the following inorganic fine particles and lubricants.

  A conventionally well-known thing can be used as an inorganic fine particle. Specifically, silica, titania, alumina, strontium titanate fine particles and the like can be preferably used. These inorganic fine particles may be hydrophobized if necessary. Specific examples of the silica fine particles include commercially available products R-805, R-976, R-974, R-972, R-812, R-809 manufactured by Nippon Aerosil Co., Ltd., HVK-2150, H- manufactured by Hoechst. 200, commercial products TS-720, TS-530, TS-610, H-5, MS-5 and the like manufactured by Cabot Corporation.

  As titania fine particles, for example, commercially available products T-805 and T-604 manufactured by Nippon Aerosil Co., Ltd., commercially available products MT-100S, MT-100B, MT-500BS, MT-600, MT-600SS, JA- 1. Commercial products TA-300SI, TA-500, TAF-130, TAF-510, TAF-510T manufactured by Fuji Titanium Co., Ltd. Commercial products IT-S, IT-OA, IT-OB, IT- manufactured by Idemitsu Kosan Co., Ltd. OC etc. are mentioned.

  Examples of the alumina fine particles include commercial products RFY-C and C-604 manufactured by Nippon Aerosil Co., Ltd. and commercial products TTO-55 manufactured by Ishihara Sangyo Co., Ltd.

  Further, it is possible to use a lubricant to further improve the cleaning property and the transfer property. Examples of the lubricant include metal salts of higher fatty acids such as the following. That is, salts of zinc stearate, aluminum, copper, magnesium, calcium, etc., zinc oleate, salts of manganese, iron, copper, magnesium, etc., zinc palmitate, salts of copper, magnesium, calcium, etc., linoleic acid And salts of zinc and calcium of ricinoleic acid.

The addition amount of these external additives and lubricants is preferably 0.1 to 10.0% by mass with respect to the whole toner including the organic fine particles described above. Examples of the method for adding external additives and lubricants include methods using various known mixing devices such as a Turbuler mixer, a Henschel mixer, a Nauter mixer, and a V-type mixer.
6). Developer The toner according to the present invention can be used as a two-component developer composed of a carrier and a toner, or as a non-magnetic one-component developer composed only of a toner.

  When the toner according to the present invention is used as a two-component developer, for example, a full-color print can be created at a high speed using a tandem image forming apparatus described later. Further, since the toner according to the present invention has a glass transition temperature of 20 ° C. or higher and 45 ° C. or lower, it is possible to produce a print compatible with so-called low temperature fixing in which the paper temperature during fixing is about 100 ° C.

  Carriers that are magnetic particles used when used as a two-component developer include conventionally known materials such as metals such as iron, ferrite, and magnetite, and alloys of these metals with metals such as aluminum and lead. It is possible to use. Among these, ferrite particles are preferable. The carrier has a volume average particle size of preferably 15 to 100 μm, more preferably 25 to 80 μm.

When the toner is used as a non-magnetic one-component developer that forms an image without using a carrier, the toner is slid and pressed against the charging member and the developing roller surface during image formation. Image formation by the non-magnetic one-component development method can simplify the structure of the developing device, and thus has an advantage that the entire image forming device can be made compact. Therefore, when the toner according to the present invention is used as a non-magnetic one-component developer, a full color print can be created with a compact color printer, and a full color print excellent in color reproducibility can be created even in a space-limited work environment. Is possible.
7). Image Formation Next, an image forming method using the toner according to the present invention will be described. FIG. 1 is a schematic view showing an example of an image forming apparatus capable of using the toner according to the present invention as a two-component developer.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  The toner according to the present invention adopts a so-called low-temperature fixing technology capable of fixing a toner image at a temperature lower than the current fixing temperature by setting the glass transition temperature to 20 ° C. or higher and 45 ° C. or lower. . That is, even when the transfer material on which the toner image formed with the toner according to the present invention is formed is subjected to a fixing process under the condition that the surface temperature of the heating roller is 90 ° C. to 150 ° C., for example, the transfer material is bent. A stable result of so-called crease fixing strength or the like for evaluating the fixing property of the toner at the location can be obtained.

  When the toner according to the present invention is used in an image forming apparatus compatible with low-temperature fixing, the surface temperature of the heating member in the fixing device is set in the above range, particularly less than 140 ° C., and the surface temperature of the heating member is set less than 130 ° C. It is possible.

  As a specific form of the fixing device, a fixing device using a heating roller shown in FIG. 2 may be mentioned. Further, when the toner according to the present invention is used, the fixing device is required to efficiently supply heat supplied from the heating member to the transfer material, and either the heating member or the pressure member has heat resistance. A fixing device called a belt fixing using a belt is preferable.

  FIG. 2 is a schematic diagram illustrating an example of a fixing device using a heating roller.

  The fixing device 24 shown in FIG. 2 includes a heating roll 240 and a pressure roll 241 in contact with the heating roll 240. In FIG. 2, 246 is a separation claw, and P is a transfer material (transfer paper) on which a toner image is formed.

  The heating roll 240a has, for example, a coating layer 82 made of a fluororesin or an elastic body formed on the surface of the cored bar 240a, and includes a heating member 244 made of a linear heater.

  The core metal 240 is made of metal and has an inner diameter of 10 to 70 mm. Although the metal which comprises the metal core 240 is not specifically limited, For example, metals, such as iron, aluminum, copper, and these alloys can be mentioned.

  The thickness of the core metal 240a is 0.1 to 15 mm, and is preferably determined in consideration of a balance between a request for energy saving (thinning) and strength (depending on constituent materials). For example, in order to maintain the same strength as that of a cored bar made of iron of 0.57 mm with a cored bar made of aluminum, the thickness needs to be 0.8 mm.

  Examples of the fluororesin constituting the surface of the coating layer 240c include polytetrafluoroethylene (PTFE) and tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA).

  The thickness of the coating layer 240c made of a fluororesin is 10 to 500 μm, preferably 20 to 400 μm.

  When the thickness of the coating layer 240c made of a fluororesin is less than 10 μm, the function as the coating layer cannot be sufficiently exhibited, and it becomes difficult to ensure the durability as the fixing device. On the other hand, when the thickness of the coating layer 240c exceeds 500 μm, the surface of the coating layer is easily damaged by paper powder. Since toner or the like is likely to adhere to the generated scratched part, there is a concern about the occurrence of image smearing due to this.

  In addition, as the elastic body constituting the coating layer 240c, it is preferable to use silicon rubber, silicon sponge rubber, or the like having good heat resistance such as LTV, RTV, and HTV.

  The Asker C hardness of the elastic body constituting the coating layer 240c is less than 80 °, preferably less than 60 °.

  Moreover, 0.1-30 mm is preferable and, as for the thickness of the coating layer 240c, 0.1-20 mm is more preferable.

  As the heating member 244, a halogen heater can be preferably used.

  The pressure roll 250 is formed by forming a coating layer 250b made of an elastic body on the surface of the cored bar 250a. The elastic body constituting the covering layer 250b is not particularly limited, and examples thereof include various soft rubbers such as urethane rubber and silicon rubber, and sponge rubber. Among these, silicon rubber and silicon sponge rubber are preferable.

  The thickness of the coating layer 250b is preferably 0.1 to 30 mm, and more preferably 0.1 to 20 mm.

  The fixing temperature (surface temperature of the heating roll 240) is a temperature at which the temperature of the transfer material can be about 100 ° C. during fixing, and is 70 to 180 ° C. depending on the fixing linear speed described later. The fixing linear velocity is preferably 80 to 640 mm / sec, and the nip width between the heating roll 240 and the pressure roll 250 is set to 8 to 40 mm, preferably 11 to 30 mm.

  The separation claw 246 is provided to prevent the transfer material heat-fixed on the heating roll 240 from being wound around the heating roll.

  FIG. 3 shows an example of a belt fixing type fixing device (a type using a belt and a heating roller) capable of fixing the toner according to the present invention.

  The fixing device 24 shown in FIG. 3 is a type that uses a belt and a heating roller to ensure a nip width, and is pressed against the heating roller 240 via the heating roller 240, the seamless belt 241, and the seamless belt 241. The pressure pad (pressure member) 242a, the pressure pad (pressure member) 242b, and the lubricant supply member 243 constitute main parts.

  The heating roller 240 is formed of a heat-resistant elastic layer 240b and a release layer (heat-resistant resin layer) 240c around a metal core (cylindrical core) 240a, and a heat source is provided inside the core 240a. A halogen lamp 244 is arranged. The surface temperature of the heating roller 240 is measured by the temperature sensor 245, and the halogen lamp 244 is feedback-controlled by a temperature controller (not shown) based on the measurement signal, so that the surface of the heating roller 240 is adjusted to a constant temperature. The seamless belt 241 is in contact with the heating roller 240 so as to be wound at a predetermined angle, thereby forming a nip portion.

  Inside the seamless belt 241, a pressure pad 242 having a low friction layer on its surface is arranged in a state of being pressed against the heating roller 240 via the seamless belt 241. The pressure pad 242 is provided with a pressure pad 242a to which a strong nip pressure is applied and a pressure pad 242b to which a weak nip pressure is applied, and is held by a holder 242c made of metal or the like.

  A belt traveling guide is attached to the holder 242c so that the seamless belt 241 slides and rotates smoothly. The belt running guide is preferably a member having a low coefficient of friction because it rubs against the inner surface of the seamless belt 241, and a member having low thermal conductivity is preferred so that heat cannot be taken away from the seamless belt 241. In addition, as a specific example of the material of the seamless belt 241, a polyimide is mentioned, for example.

  The toner image formed with the toner according to the present invention is finally transferred onto the transfer material P, and fixed on the transfer material by a fixing process to form an image. The transfer material P used for the image formation is a support for holding a toner image, and is usually called an image support, a recording material, or transfer paper. Specifically, various transfer materials such as plain paper and fine paper from thin paper to thick paper, coated printing paper such as art paper and coated paper, commercially available Japanese paper and postcard paper, plastic film for OHP, cloth, etc. However, it is not limited to these.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, the embodiment of this invention is not limited to this.
1. Production of “Organic Fine Particles 1-7” (1) Production of “Organic Fine Particle 1” In a separable flask equipped with a stirrer, a dropping funnel, a nitrogen introduction tube, and a reflux condenser, 828 parts by mass of ion-exchanged water was added. The temperature was raised to 70 ° C. under a constant stirring condition under a nitrogen gas stream, and after 30 minutes, 0.6 parts by mass of ammonium persulfate as a polymerization initiator was added.

  Next, 108 parts by weight of “emulsified dispersion A” containing the following compound was added all at once to the aqueous solution to which the polymerization initiator was added, and then the temperature of the polymerization reaction system was maintained at 70 ° C. The polymerization reaction was performed for 3 hours. In addition, the emulsification dispersion liquid containing the following compound was produced using the homogenizer.

Ion-exchanged water 54 parts by mass Tetramethylolpropane triacrylate (solubility in water at 25 ° C. is 1% by mass or less) 36 parts by mass A 16% by mass aqueous solution of sodium dodecylbenzenesulfonate 18 parts by mass Next, the following compound is emulsified by a homogenizer Then, 252 parts by mass of “Emulsified Dispersion B” prepared above was dropped into the polymerization reaction system from a dropping funnel at a dropping rate of 1 g / min over about 4 hours.

Ion-exchanged water 126 parts by mass Trimethylolpropane triacrylate (solubility in water at 25 ° C. is 1% by mass or less) 69 parts by mass Ethylene glycol dimethacrylate 28 parts by mass 16% by mass aqueous solution of sodium dodecylbenzenesulfonate 15 parts by mass After completion of the dropping of the liquid, the polymerization reaction was continued for another 2 hours to produce a crosslinked resin fine particle emulsion. When the number average particle diameter of the crosslinked resin fine particles in the crosslinked resin fine particle emulsion was measured, it was 50 nm.

Next, the crosslinked resin fine particle emulsion obtained above was lyophilized using a freeze dryer to obtain a white powdery product composed of the crosslinked resin fine particles. This is designated as “organic fine particle 1”.
(2) Preparation of “Organic Fine Particle 2” → Same as and larger than 1. In the preparation of “Organic Fine Particle 1”, “Emulsification of 16% by mass aqueous solution of sodium dodecylbenzenesulfonate” into 13% by mass aqueous solution. The addition amount of “trimethylolpropane triacrylate” in “dispersion B” was changed to 72 parts by mass, and the addition amount of “ethylene glycol dimethacrylate” was changed to 8 parts by mass. Other than that, “organic fine particles 3” having a number average particle diameter of 90 nm were prepared in the same procedure. The amount was changed to 18 parts by mass. Other than that, “organic fine particles 2” having a number average particle diameter of 70 nm were prepared in the same procedure.
(3) Preparation of “organic fine particle 3” → much larger than 1 In preparation of the above “organic fine particle 1”, “16% by mass aqueous solution of sodium dodecylbenzenesulfonate” is changed to 8% by mass aqueous solution, “emulsified dispersion B The amount of “trimethylolpropane triacrylate” added in “” was changed to 84 parts by mass, and the amount of “ethylene glycol dimethacrylate” added was changed to zero. Other than that, “organic fine particles 3” having a number average particle diameter of 100 nm were prepared in the same procedure.
(4) Production of “organic fine particles 4” In a separable flask equipped with a stirrer, a dropping funnel, a nitrogen introducing tube, and a reflux condenser, 300 parts by mass of ion-exchanged water and 7 parts by mass of hexadecyltrimethylammonium chloride were added. The mixture was added and heated to 75 ° C. under a constant stirring condition under a nitrogen gas stream. To this solution, 1 part by mass of 2,2-azobis (2- (2-imidazolin-2-yl) propane) 100% neutralized aqueous solution of acetic acid was added dropwise over 10 minutes, followed by further aging treatment for 5 minutes. It was.

  Next, 10 parts by mass of methyl methacrylate was dropped over 5 minutes, and then an aging treatment for 5 minutes was performed to advance the polymerization reaction.

  Next, “Emulsified dispersion C” prepared by adding and stirring the following compound in a solution obtained by mixing 15 parts by mass of hexadecyltrimethylammonium chloride and 270 parts by mass of ion-exchanged water is used as the above polymerization reaction system. It was dripped over 40 minutes. “Emulsified dispersion C” containing the following compound was prepared using a homogenizer.

Methyl methacrylate 10 parts by mass Styrene 30 parts by mass n-Butyl methacrylate 25 parts by mass Glycidyl methacrylate 5 parts by mass Neopentyl glycol dimethacrylate 30 parts by mass After the above “emulsified dispersion C” was added dropwise, the polymerization reaction was continued for 40 minutes. Then, it cooled and the process similar to the time of preparation of "organic fine particle 1" was performed, and the crosslinked resin fine particle emulsion was produced. When the number average particle diameter of the crosslinked resin fine particles in the crosslinked resin fine particle emulsion was measured, it was 200 nm.

Next, the crosslinked resin fine particle emulsion obtained above was lyophilized using a freeze dryer to obtain a white powdery product composed of the crosslinked resin fine particles. This is designated as “organic fine particles 4”.
(5) Production of “Organic Fine Particle 5” In the production of “Organic Fine Particle 4”, the addition amount of “Neopentyl glycol dimethacrylate” in “Emulsified Dispersion C” was changed to 15 parts by mass. Other than that, “organic fine particles 5” having a number average particle diameter of 100 nm were prepared in the same procedure.
(6) Production of “Organic Fine Particle 6” In the production of “Organic Fine Particle 1”, the number average was obtained by the same procedure except that “16% by mass aqueous solution of sodium dodecylbenzenesulfonate” was changed to 4% by mass aqueous solution. “Organic fine particles 7” having a particle size of 230 nm were prepared.
(7) Production of “Organic Fine Particles 7” In the production of “Organic Fine Particles 1”, the number average was obtained by the same procedure except that “16 mass% aqueous solution of sodium dodecylbenzenesulfonate” was changed to 22 mass% aqueous solution. “Organic fine particles 7” having a particle diameter of 40 nm were produced.

  Table 1 shows the number average particle diameter and the degree of crosslinking of the organic fine particles.

2. 2. Production of “colored particles 1 to 5” 2-1. Preparation of core resin particles (Preparation of core resin particles 1)
(1) First-stage polymerization In a reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introducing device, the following compounds are added and mixed:
Styrene 110.9 parts by mass n-butyl acrylate 52.8 parts by mass Methacrylic acid 12.3 parts by mass
After adding 93.8 parts by mass of paraffin wax “HNP-57 (Nippon Seiki Co., Ltd.)”, it was heated to 80 ° C. and dissolved to obtain a polymerizable monomer solution.

  On the other hand, a surfactant solution was prepared by dissolving 2.9 parts by mass of sodium polyoxyethylene (2) dodecyl ether sulfate in 1340 parts by mass of ion-exchanged water. After heating the surfactant solution to 80 ° C., the polymerizable monomer solution is added, and the polymerizable monomer is added by a mechanical disperser “CLEAMIX (manufactured by M Technique)” having a circulation path. The solution was mixed and dispersed for 2 hours. Then, a dispersion of emulsified particles (oil droplets) having an average particle size of 245 nm was prepared.

  Next, after adding 1460 parts by mass of ion-exchanged water, an initiator solution in which 6 parts by mass of a polymerization initiator (potassium persulfate) is dissolved in 142 parts by mass of ion-exchanged water, 1.8 parts by mass of n-octyl mercaptan, Was added to bring the temperature to 80 ° C. This system was heated and stirred at 80 ° C. for 3 hours to perform polymerization (first stage polymerization) to produce resin particles. This is designated as “resin particle C1”.

(2) Second stage polymerization (formation of outer layer)
An initiator solution prepared by dissolving 5.1 parts by mass of potassium persulfate in 197 parts by mass of ion-exchanged water is added to the “resin particle C1”, and the following polymerizable monomer is mixed under a temperature condition of 80 ° C. The monomer mixture obtained was added dropwise over 1 hour. The monomer mixture is
Styrene 282.2 parts by mass n-butyl acrylate 134.4 parts by mass Methacrylic acid 31.4 parts by mass n-octyl mercaptan 4.93 parts by mass (Formation of outer layer) was performed. Then, it cooled to 28 degreeC and obtained "resin particle 1 for cores".

  The formed “core resin particle 1” had a weight average molecular weight of 21,300, a mass average particle diameter of 180 nm, and a glass transition temperature of 39 ° C.

(Preparation of core resin particles 2)
In the preparation of “core resin particle 1”, the addition amount of the polymerizable monomer in the first stage polymerization is
Styrene 90.8 parts by mass n-butyl acrylate 72.7 parts by mass Methacrylic acid 12.3 parts by mass, the addition amount of the polymerizable monomer in the second stage polymerization,
Styrene 274.1 parts by mass n-butyl acrylate 168.6 parts by mass A “core resin particle 2” was prepared in the same manner except that it was changed to 5.2 parts by mass of methacrylic acid. The “core resin particle 2” had a weight average molecular weight of 22,000, a mass average particle diameter of 180 nm, and a glass transition temperature of 20.1 ° C.

(Preparation of core resin particle 3)
In the preparation of “core resin particle 1”, the addition amount of the polymerizable monomer in the first stage polymerization is
Styrene 115.3 parts by weight n-butyl acrylate 48.4 parts by weight Methacrylic acid 12.3 parts by weight, the addition amount of the polymerizable monomer in the second stage polymerization,
Styrene 293.4 parts by mass n-butyl acrylate 123.2 parts by mass Methacrylic acid 3 Core parts were prepared in the same manner except for changing to 31.4 parts by mass. The “core resin particle 3” had a weight average molecular weight of 22,500, a mass average particle diameter of 180 nm, and a glass transition temperature of 44 ° C.

(Preparation of core resin particles 4)
In the preparation of “core resin particle 1”, the addition amount of the polymerizable monomer in the first stage polymerization is
Styrene 119.7 parts by mass n-butyl acrylate 44.0 parts by mass Methacrylic acid 12.3 parts by mass, the addition amount of the polymerizable monomer in the second stage polymerization,
Styrene 304.6 parts by mass n-Butyl acrylate 112.0 parts by mass Methacrylic acid 3 Core parts were prepared in the same manner except that they were changed to 31.4 parts by mass. The “core resin particles 4” had a weight average molecular weight of 22,500, a mass average particle diameter of 180 nm, and a glass transition temperature of 49 ° C.

(Preparation of core resin particles 5)
In the preparation of “core resin particle 1”, the addition amount of the polymerizable monomer in the first stage polymerization is
Styrene 103.5 parts by mass n-butyl acrylate 70.4 parts by mass Methacrylic acid 2.1 parts by mass, the addition amount of the polymerizable monomer in the second stage polymerization,
Styrene 263.4 parts by mass n-butyl acrylate 179.2 parts by mass A “core resin particle 5” was prepared in the same manner except that the amount was changed to 5.4 parts by mass of methacrylic acid. The “core resin particles 5” had a weight average molecular weight of 22,500, a mass average particle diameter of 180 nm, and a glass transition temperature of 18 ° C.
2-2. Preparation of resin particles for shell 2.0 parts by mass of polyoxyethylene (2) sodium dodecyl ether sulfate was dissolved in 3000 parts by mass of ion-exchanged water in a reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introduction device. The surfactant solution was charged, and the internal temperature was raised to 80 ° C. while stirring at a stirring speed of 230 rpm under a nitrogen stream.

A polymerizable monomer obtained by adding an initiator solution in which 10 parts by mass of a polymerization initiator (potassium persulfate: KPS) is dissolved in 200 parts by mass of ion-exchanged water to this surfactant solution and mixing the following compounds. The mixed solution was added dropwise over 3 hours. The polymerizable monomer mixed solution is
Styrene 528 parts by mass n-butyl acrylate 176 parts by mass Methacrylic acid 120 parts by mass n-octyl mercaptan 22 parts by mass After dropping the polymerizable monomer mixed solution, the system was heated and stirred at 80 ° C. for 1 hour to carry out polymerization to prepare resin particles. This is referred to as “shell resin particles”.

The “resin particles for shell” had a weight average molecular weight of 12,000, a mass average particle size of 120 nm, and a glass transition temperature of 53 ° C. 2-3. Preparation of Colorant Dispersion While stirring 900 parts by weight of an aqueous solution of 10% by weight sodium dodecyl sulfate, 210 parts by weight of the colorant “CI Pigment Blue 15: 3” was gradually added, and then the stirring device “Claire Cyan colorant particle dispersion was prepared by dispersing using “Mix” (manufactured by M Technique). This is designated as “colorant dispersion C1”. The average dispersion diameter of the colorant particles in the colorant dispersion was measured using a dynamic light scattering particle size analyzer “Microtrack UPA150” (manufactured by Nikkiso Co., Ltd.), and found to be 150 nm.
2-4. Production of “colored particles 1 to 5” (production of colored particles 1)
(1) Formation of core part (salting out / fusion (association / fusion) process)
In a reaction vessel equipped with a stirrer, temperature sensor, cooling pipe, nitrogen introduction device,
"Resin particle 1 for core" 420.7 parts by mass (solid content conversion)
900 parts by mass of ion-exchanged water “Colorant particle dispersion Bk1” 200 parts by mass (in terms of solid content)
Was added and stirred. After adjusting the temperature in the reaction vessel to 30 ° C., 5 mol / liter sodium hydroxide aqueous solution was added to this solution to adjust the pH to 9.

  Next, an aqueous solution in which 2 parts by mass of magnesium chloride hexahydrate is dissolved in 1000 parts by mass of ion-exchanged water is added to the reaction system over 10 minutes at 30 ° C. with stirring, and the mixture is allowed to stand for 3 minutes. Once started, the system was heated to 65 ° C. over 60 minutes to initiate the association. In this state, the particle size of the associated particles was measured with “Multisizer 3 (manufactured by Beckman Coulter)”, and when the volume-based median system (D50) of the particles became 5.5 μm, sodium chloride 40.2 An aqueous solution in which a part by mass was dissolved in 1000 parts by mass of ion-exchanged water was added to stop particle size growth. Further, as a ripening treatment, the fusion was continued by heating and stirring at a liquid temperature of 70 ° C. for 1 hour to form “core part 1”.

The circularity of the “core part 1” was measured by “FPIA2100” (manufactured by Systex) and found to be 0.930.
(2) Shell formation (shelling process)
Next, the reaction vessel in which the above “core part 1” was prepared was brought to 65 ° C., and “resin particles for shell” 50 parts by mass (in terms of solid content)
Was added. Furthermore, after adding an aqueous solution in which 2 parts by mass of magnesium chloride hexahydrate was dissolved in 1000 parts by mass of ion-exchanged water over 10 minutes, the temperature was raised to 70 ° C. (shelling temperature) and stirring was continued for 1 hour. did. In this way, “shell resin particles” were fused on the surface of “core part 1”, and then aged at 75 ° C. for 20 minutes to form a shell layer.

After the aging treatment, 40.2 parts by mass of sodium chloride was added and cooled to 30 ° C. at a cooling rate of 8 ° C./min to obtain a dispersion of “colored particles 1”.
(3) Washing and drying step The dispersion of “colored particles 1” is subjected to solid-liquid separation using a basket-type centrifuge “MARKIII model number 60 × 40 (Matsumoto Machine Co., Ltd.)”. A toner cake of “colored particles 1” was formed. Then, the “colored particle 1” was repeatedly washed and solid-liquid separated using the basket type centrifuge until the electric conductivity of the filtrate reached 5 μS / cm. After the filtrate has a predetermined electrical conductivity, a drying apparatus “Flash Jet Dryer (manufactured by Seishin Enterprise Co., Ltd.)” is used to perform a drying treatment until the water content becomes 0.5% by mass. 1 "was obtained. “Colored particle 1” had a core-shell structure, a volume-based median diameter (D50) of 6.0 μm, and a glass transition temperature of 39.5 ° C.

(Preparation of colored particles 2)
In the production of “colored particles 1”, “colored particles 2” were produced by the same procedure except that the core resin particles used for forming the core portion were changed to “core resin particles 2”. “Colored particle 2” had a volume-based median diameter (D50) of 6.0 μm and a glass transition temperature of 20.5 ° C.

(Preparation of colored particles 3)
In the production of “colored particles 1”, “colored particles 3” were produced in the same procedure except that the core resin particles used for forming the core portion were changed to “core resin particles 3”. “Colored particles 3” had a volume-based median diameter (D50) of 6.0 μm and a glass transition temperature of 44.5 ° C.

(Preparation of colored particles 4)
In the production of “colored particles 1”, “colored particles 4” were produced by the same procedure except that the core resin particles used for forming the core portion were changed to “core resin particles 4”. “Colored particles 4” had a volume-based median diameter (D50) of 6.0 μm and a glass transition temperature of 49.5 ° C.

(Preparation of colored particles 5)
In the production of “colored particles 1”, “colored particles 5” were produced in the same procedure except that the core resin particles used for forming the core portion were changed to “core resin particles 5”. “Colored particles 5” had a volume-based median diameter (D50) of 6.1 μm and a glass transition temperature of 18.8 ° C.

  Table 2 shows the glass transition temperature values of the colored particles.

3. Production of “Toners 1 to 11 (Two-Component Developers 1 to 11)” The cyan “colored particles 1 to 5” produced as described above were subjected to the following external addition treatment to obtain cyan. Colored “Toners 1 to 11” were produced. That is, 1% by mass of hydrophobic silica (number average particle size = 12 nm, degree of hydrophobization = 68), 1% by mass of hydrophobic titania (number average particle size = 20 nm, degree of hydrophobization = 63), and the organic substances described in Table 1 Fine particles were added in the amounts shown in Table 3 and mixed with a “Henschel mixer (Mitsui Miike Chemical Co., Ltd.)”.

  Next, the durability of the “organic fine particles 1 to 7” externally added to the produced “toners 1 to 11” was evaluated. According to the procedure of the forced stirring test described above, the shape factor SF-1 before and after the forced stirring test, the rate of change, and the ratio of deformed particles were calculated. The results are shown in Table 3.

Each toner was mixed with a ferrite carrier having a volume average particle diameter of 35 μm coated with a silicone resin to prepare “two-component developers 1 to 11” having a toner concentration of 6%. These “two-component developers 1 to 11” were mounted on the following image forming apparatus and evaluated.
4). Evaluation Experiment (1) Evaluation Conditions Image evaluation uses a commercially available multifunction machine “bizhub Pro C500” (manufactured by Konica Minolta Business Technologies) that employs a printed image electrophotographic method, and is A4 quality paper (64 g / m ² ). A print was produced to output a cyan toner image on top.

  The printing was performed by continuous printing of 5000 sheets in a total of A4 size prints in a normal temperature and humidity environment (20 ° C., 55% RH). When performing the above-described continuous printing, the 101st to 200th prints were performed with the separation claw of the fixing device removed in order to evaluate the winding around the heating roller described below. The prints from the 4400th sheet to the 4900th sheet are output on both sides of the sheet. Although not included in the description of evaluation items described later, it was observed whether smooth print creation could be performed during continuous printing.

  The output image has a fine line image (8 lines / mm, 5 lines / mm), a halftone image (pixel density of 0.80), a white background image, and a solid image (pixel density of 1.30) each divided into 1/4 equal parts. An A4 size image was output, and the output image during double-sided printing was a text original with a pixel rate of 12%.

  The fixing device of the image forming apparatus is composed of a heating roller and a pressure belt shown in FIG. 3, and the surface material and surface temperature of the heating roller are set as follows.

Fixing speed: 230mm / sec
Heat roller surface material: Polytetrafluoroethylene (PTFE)
Heating roller surface temperature: 135 ° C (however, set as follows when evaluating low-temperature fixability)
Furthermore, after making the above 5000 prints, the surface temperature of the heating roller was changed to 90 ° C., 105 ° C., and 125 ° C., and 100 sheets were continuously printed at each surface temperature to evaluate the low-temperature fixability. It was.
(2) Evaluation Items Evaluation was performed for “transfer rate”, “halftone unevenness”, “low temperature fixing performance”, and “separation performance at low temperature fixing” as shown below.

<Transfer rate>
The reflection density in the solid image (pixel density is 1.30) portion on the first and 5000th prints was measured and evaluated as follows.

  The transfer rate is originally calculated from the ratio of the mass of the toner transferred onto the transfer material and the mass of the toner developed on the photoconductor, as represented by the following formula. A value of 80% or more is regarded as acceptable, and a value of 90% or more is particularly preferred.

Transfer rate (%) = (mass of toner transferred onto transfer material / mass of toner developed on photoreceptor) × 100
In this evaluation, it was determined that it was difficult to measure the transfer rate from the above equation, and the transfer rate was determined by replacing the toner mass with the image density. That is, when a solid image with a pixel density of 1.30 is output on a transfer sheet, the reflection density is 1.04 when the reflection density of the solid image created on the print is 1.30 and the transfer rate is 100%. The transfer rate was 80%, and the transfer rate was 90% when the reflection density was 1.27. A sample having a reflection density of 1.04 or higher was accepted.

<Half tone unevenness>
After the continuous printing of 5000 sheets, a halftone image having an image density of 0.4 was printed on both sides of A4 size high quality paper (64 g / m ² ), and the created image was visually evaluated. The evaluation is as follows.

A: Unevenness is not recognized. O: Slight unevenness is confirmed but there is no practical problem. X: Unevenness is recognized and there is a practical problem.

<Low temperature fixability>
Before the continuous printing of 5000 sheets, the surface temperature of the heating roller of the fixing device of the evaluation machine was set to 90 ° C., 105 ° C., and 120 ° C., and A4 size high quality paper (64 g / m 2) at each set temperature. ^{In 2} ), 100 continuous prints were made. The fixed image output on the 10th print at each set temperature was evaluated.

The fixing strength of the obtained printed image is evaluated by the fixing rate using a method according to the mending tape peeling method described in Chapter 9 Section 1.4 of “Basics and Applications of Electrophotographic Technology: Edition of Electrophotographic Society”. did. Specifically, a 2.54 cm square beta cyan print image with an amount of cyan toner attached of 0.6 mg / cm ² is created, and “Scotch Mending Tape (manufactured by Sumitomo 3M)” is pasted on the fixed image. Then, peel off and measure the image density before and after. Then, the residual ratio of the toner was calculated from the density before and after the tape peeling, and this was used as the fixing ratio.

The surface temperature of the heating roller capable of forming a toner image with a fixing rate of 95% or more was defined as the minimum fixing temperature. The surface temperature of the heating roller was measured with a non-contact thermometer, and the image density was measured with a reflection densitometer “RD-918 (manufactured by Macbeth)”. Evaluation is as follows:
A: The minimum fixing temperature is 95 ° C. ○: The minimum fixing temperature is 95 ° C. and 105 ° C. ×: The minimum fixing temperature is only 120 ° C., and the minimum fixing temperature is 105 ° C. or less is accepted. .

<Separability at low temperature fixing>
At the time of carrying out the fixing strength evaluation, the separability between the heating roller and the high-quality paper of A4 size at each set temperature was evaluated. In the evaluation, 100 sheets of A4 size high-quality paper were continuously output at each set temperature, and the transfer sheet separation property through the separation claw and the finished image were evaluated as follows. The evaluation criteria were “◯” and “△”.

○: 100 transfer sheets could be separated from the heating roller without curling. Δ: Several transfer sheets separated by the heating roller and the separation claw were seen, but there were some images where the separation claw trace could be confirmed on the image. No: There was a transfer sheet that was separated by a heating roller and a separation claw, and there was a sheet on which an image of the separation claw was confirmed.

  The results are shown in Table 4.

  As shown in Table 4, the electrostatic image developing toners described in Examples 1 to 7 corresponding to the present invention have good results in transfer rate and halftone unevenness even after continuous printing of 5000 sheets. It was. Moreover, the evaluation regarding the low-temperature fixability also gave a favorable result. It should be noted that troubles such as tacking and winding were not observed when the above-described 5000 continuous printing was performed. From these results, it can be seen that the toners of the examples can sufficiently exude the release agent from the toner surface at the time of fixing without undergoing deformation or burying even when subjected to stress during image formation, and can perform stable low-temperature fixing. To be judged.

  On the other hand, the electrostatic image developing toners described in Comparative Examples 1 to 4 falling outside the scope of the present invention did not sufficiently satisfy the above evaluation items. In addition, when continuous printing was performed, tacking or winding was observed.

1 is a schematic diagram illustrating an example of a two-component developing type image forming apparatus. It is a schematic diagram showing an example of a roller fixing type fixing device. It is a schematic diagram showing an example of a belt fixing type fixing device.

Explanation of symbols

1 Photoconductor (Photoconductor drum)
4 Development device (toner cartridge)
6 Cleaning Device 7 Intermediate Transfer Belt 10 Image Forming Unit 24 Fixing Device 240 Heating Roller 241 Pressure Belt (Seamless Belt)
P Transfer material (recording material)

Claims (2)

In the toner for developing an electrostatic charge image obtained by externally adding organic fine particles having a number average particle diameter of 50 nm or more and 200 nm or less to colored particles containing at least a resin and a colorant,
The electrostatic charge image developing toner has a glass transition temperature of 20 ° C. or higher and 45 ° C. or lower,
A toner for developing an electrostatic charge image, wherein when the organic fine particles are subjected to a forced stirring test, the rate of change of the shape factor SF-1 of the organic fine particles before and after the test is 10% or less. The electrostatic charge image developing toner according to claim 1, wherein a ratio of the organic fine particles deformed by the forced stirring test is 30% by number or less.

Images