Negative charging electrophotographic toner

The present invention relates to a toner for developing an electrostatic charge image in an image forming method such as electrophotographic, electrostatic recording and the like.

The developing methods applied to the electrophotographic method and the like are roughly classified into a dry developing method and a wet developing method. The former can be further divided into a method using a two-component developer and a method using a one-component developer. As the toner that can be used in these developing methods, fine powder in which a dye or a pigment is dispersed in a natural or synthetic resin has been conventionally used. For example, particles in which a colorant is dispersed in a binder resin such as polystyrene and finely pulverized to about 5 to 15 μm are used as toner. Further, as the magnetic toner, one containing magnetic particles such as magnetite is used.

Both toners need to have a positive or negative charge, depending on the polarity of the statically charged latent image to be developed. In order to retain the electric charge of the toner, the triboelectric property of the resin, which is a component of the toner, can be used. However, in this method, due to insufficient charge, sufficient developability such as fog of the obtained image and reduction of image density can be used. May not be obtained. Therefore, in order to impart a desired triboelectric property to the toner, a charge control agent is added.

The toner containing the charge control agent has different charge characteristics depending on the combination of the type of the binder resin and the type of the charge control agent. Among such charge control agents, it is known to use a monoazo metal complex salt compound. However, these charge control agents have a drawback that the quality of the initial copied image is liable to fluctuate because the affinity of the toner for the binder resin and the effect of imparting triboelectric charge are insufficient. In addition, it is easily affected by temperature and humidity, and has a drawback of a decrease in the amount of charge in an environment of high humidity. Although some monoazochromic complex salt compounds solve these problems, the possibility that a very small amount of harmful hexavalent chromium is generated during combustion disposal cannot be completely denied, and it is given to the environment and the human body. There are concerns about the impact. Therefore, there has been a demand for a charge control agent that uses a safer metal and is sufficiently satisfactory in terms of performance.

Although some high-performance monoazo iron complex salt compounds have been disclosed (see, for example, Patent Document 1), all of the good-performance monoazo iron complex salts are azo complexes having a plurality of nitro groups. There is a risk of ignition and explosion. In particular, when the central metal is iron, the risk of ignition and explosion is significant, and the drying and crushing processes are extremely dangerous operations. Further, since the pulverized toner is generally kneaded by an extrusion kneader or the like and pulverized to produce the toner, there is a considerable possibility of powder explosion during the toner production. When the central metal is chromium, the risk of ignition and explosion is lower than that of iron, but even in this case, the obtained monoazochrome complex salt compound having a nitro group becomes a self-reactive substance (class 5 dangerous substance). Applicable and restricted in handling. A toner using a monoazo iron complex salt compound in which the central metal is iron as a charge control agent is disclosed (see, for example, Patent Document 2), and it is practical as a negatively charged charge control agent that does not use chromium as the central metal. Some have a charge amount.

<patcit num="1"><text>Special Table No. 8-500912</text></patcit><patcit num="2"><text>Japanese Unexamined Patent Publication No. 61-155464</text></patcit>

<p> In recent years, printers and copiers that apply the electrophotographic method have become widespread, and the printing speed is increasing year by year. It is becoming more and more popular. That is, it is required more than the conventional toner for the toner containing the iron complex salt compound to instantly maintain the appropriate charge when the state is changed from the hibernation state to the output state. The present invention provides a negatively charged electrophotographic toner which has a high charge amount, has a remarkably good charge rise, and can maintain a stable charge amount without being affected by temperature and humidity. The purpose is.</p>

<p> As a result of research, the present inventors have a high charge amount by using an iron complex salt compound and by keeping the compound content, which is a specific intermediate in the iron complex salt compound, below a certain range in the toner. It was found that the rise of charge is remarkably good and a stable charge amount is maintained without being affected by temperature and humidity. That is, the present invention has the following general formula [1].</p><p><chemistry num="1"><img file="JP2005292823A_D0001.tif" /></chemistry></p><p>(In the formula, A and B independently represent a hydrogen atom and an alkyl group or halogen atom having 1 to 8 carbon atoms, X represents a hydrogen atom and an alkyl group or halogen atom having 1 to 8 carbon atoms, respectively, and Y represents a hydrogen atom and an alkyl group or halogen atom having 1 to 8 carbon atoms. Represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or a substituted or unsubstituted aromatic ring group. J represents a hydrogen ion, an alkali metal ion, an ammonium ion, or an alkylammonium ion, and in J these ions represent. A toner containing α% by mass of a 2: 1 type iron complex salt compound represented by (2 or more) as a charge control agent, and β% by mass as an impurity in the iron complex salt compound. The following general formula [2]</p><p><chemistry num="2"><img file="JP2005292823A_D0002.tif" /></chemistry></p><p>(In the formula, A and B independently represent a hydrogen atom and an alkyl group or halogen atom having 1 to 8 carbon atoms, X represents a hydrogen atom and an alkyl group or halogen atom having 1 to 8 carbon atoms, respectively, and Y represents a hydrogen atom and an alkyl group or halogen atom having 1 to 8 carbon atoms. The monoazo compound represented by a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or a substituted or unsubstituted aromatic ring group) is set to α × β 10 in order to reduce the content to the toner to 1000 ppm or less. It is a negatively charged electrophotographic toner characterized by being manufactured under setting control.</p><p> The present invention preferably has the following general formula [3].</p><p><chemistry num="3"><img file="JP2005292823A_D0003.tif" /></chemistry></p><p>(In the formula, X represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or a halogen atom, and C and D are independently hydrogen atoms, an alkyl group having 1 to 8 carbon atoms, and an alkoxy having 1 to 8 carbon atoms. It represents a group or a halogen atom, where J represents a hydrogen ion, an alkali metal ion, an ammonium ion, or an alkylammonium ion, and in J, these ions may be a mixture of two or more.) 2 A toner containing α% by mass of a: 1-type iron complex salt compound as a charge control agent, and β% by mass as an impurity in the iron complex salt compound is contained in the following general formula [4].</p><p><chemistry num="4"><img file="JP2005292823A_D0004.tif" /></chemistry></p><p>(In the formula, X represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or a halogen atom, and C and D are independently hydrogen atoms, an alkyl group having 1 to 8 carbon atoms, and an alkoxy having 1 to 8 carbon atoms. A negatively charged electrophotograph characterized in that a monoazo compound represented by (representing a group or a halogen atom) was produced by setting and controlling α × β 10 in order to reduce the content to toner to 1000 ppm or less. Toner for use.</p><p> Another aspect of the present invention is the following general formula [1].</p><p><chemistry num="5"><img file="JP2005292823A_D0005.tif" /></chemistry></p><p>(In the formula, A and B independently represent a hydrogen atom and an alkyl group or halogen atom having 1 to 8 carbon atoms, X represents a hydrogen atom and an alkyl group or halogen atom having 1 to 8 carbon atoms, respectively, and Y represents a hydrogen atom and an alkyl group or halogen atom having 1 to 8 carbon atoms. Represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or a substituted or unsubstituted aromatic ring group. J represents a hydrogen ion, an alkali metal ion, an ammonium ion, or an alkylammonium ion, and in J these ions represent. A toner containing α% by mass of a 2: 1 type iron complex salt compound represented by (2 or more) as a charge control agent, and β% by mass as an impurity in the iron complex salt compound. The following general formula [2]</p><p><chemistry num="6"><img file="JP2005292823A_D0006.tif" /></chemistry></p><p>(In the formula, A and B independently represent a hydrogen atom and an alkyl group or halogen atom having 1 to 8 carbon atoms, X represents a hydrogen atom and an alkyl group or halogen atom having 1 to 8 carbon atoms, respectively, and Y represents a hydrogen atom and an alkyl group or halogen atom having 1 to 8 carbon atoms. The monoazo compound represented by a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or a substituted or unsubstituted aromatic ring group) is set to α × β 10 in order to reduce the content to the toner to 1000 ppm or less. It is an impurity suppression management method at the time of manufacturing a negatively charged electrophotographic toner, which is characterized in that the setting is controlled.</p><p> Also in another aspect of the present invention, the following general formula [3] is preferable.</p><p><chemistry num="7"><img file="JP2005292823A_D0007.tif" /></chemistry></p><p>(In the formula, X represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or a halogen atom, and C and D are independently hydrogen atoms, an alkyl group having 1 to 8 carbon atoms, and an alkoxy having 1 to 8 carbon atoms. It represents a group or a halogen atom, where J represents a hydrogen ion, an alkali metal ion, an ammonium ion, or an alkylammonium ion, and in J, these ions may be a mixture of two or more.) 2 A toner containing α% by mass of a: 1-type iron complex salt compound as a charge control agent, and β% by mass as an impurity in the iron complex salt compound is contained in the following general formula [4].</p><p><chemistry num="8"><img file="JP2005292823A_D0008.tif" /></chemistry></p><p>(In the formula, X represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or a halogen atom, and C and D are independently hydrogen atoms, an alkyl group having 1 to 8 carbon atoms, and an alkoxy having 1 to 8 carbon atoms. Negatively charged electrophotographic toner production, characterized in that the monoazo compound represented by (representing a group or a halogen atom) is set and controlled to α × β 10 in order to reduce the content to the toner to 1000 ppm or less. It is a method of controlling impurities at the time.</p><p> Among the negatively charged electrophotographic toners of the present invention, those having excellent performance are those in which X is a methyl group, C and D are hydrogen atoms, and X is methyl in the general formula [3]. Examples of the group include those in which C is a hydrogen atom and D is a 4-chloro group, X is a methyl group, C is a 3-chloro group, and D is a 4-chloro group. Further, in the case of these 2: 1 type iron complex salt compounds, the method is also satisfactorily applied to the impurity suppression control method at the time of producing the negatively charged electrophotographic toner of the present invention.</p>

<p> Since the negatively charged electrophotographic toner of the present invention has a specific impurity content suppressed by the impurity suppression management method at the time of toner production, it has a high charge amount, a quick rise of charge, and environmental stability. Are better. Further, in the negatively charged electrophotographic toner of the present invention, since the 2: 1 type iron complex salt compound in the toner does not have a nitro group in the structural formula, powder explosion does not occur during toner production. Since it does not contain metals such as chromium, there is no possibility that harmful substances will be generated even if it is burned or oxidized, so it is safe for the environment. It is also suitable as an impurity control control method during toner production.</p>

In the impurity suppression control method at the time of producing the negatively charged electrophotographic toner of the present invention, it is an impurity in the 2: 1 type iron complex salt compound represented by the general formula [1] in the first step, which is the general formula [2]. The monoazo compound content β represented by is analyzed. In the second step, depending on the obtained β value, whether to directly move to the next toner manufacturing step or to re-purify the 2: 1 type iron complex salt compound represented by the general formula [1]. decide. If the β value is large, the amount of the 2: 1 type iron complex salt compound added to the toner produced in the third stage is limited. In the case of a toner in which the amount of the 2: 1 type iron complex salt compound added is low, even if the β value is slightly large, it is possible to directly shift to the third stage toner production as it is. However, if the amount of the 2: 1 type iron complex salt compound added to the toner is reduced too much, the performance of the toner will be impaired. When the β value becomes higher, the 2: 1 type iron complex salt compound will be purified again. In this way, by analyzing the β value in advance in the first stage, it is possible to surely reduce the risk factor of producing poor quality toner. On the contrary, it is possible to surely reduce the burden of being forced to purify excessively. Furthermore, this means that the monoazo compound content β represented by the general formula [4], which is an impurity in the 2: 1 type iron complex salt compound represented by the general formula [3], is analyzed in the first step. Also, the same effect as those described above can be obtained.

As a means for analyzing the monoazo compound content β represented by the general formula [2] or the general formula [4] in the first stage in the impurity suppression control method during the production of the negatively charged electrophotographic toner of the present invention, the speed is high. Liquid chromatography is suitable. Other gas chromatography methods can also be adopted. Both are suitable means for controlling impurities during compound production.

Type 2: 1 when produced in a 2: 1 type iron complex salt compound represented by the general formula [1] or the general formula [3], and when the β value is large in the first step and repurification is required. As a method for removing the monoazo compound represented by the general formula [2] or the general formula [4], which is an impurity in the iron complex salt compound, it is most suitable to use the solubility difference. This is because the monoazo compound has a relatively high solubility in a solvent.

As a method for removing the monoazo compound which is an impurity, a method of washing with methanol, dimethylformamide (DMF), etc., a method of recrystallizing with methanol, DMF, etc., a solvent such as tetrahydrofuran (THF), DMF, dimethyl sulfoxide (DMSO), etc. There are a method of dissolving and crystallizing using a low-solubility solvent such as cyclohexane, and a method of further increasing the purity, such as a method of separating on a column by chromatography and then extracting using a polar solvent. Or it is possible by combining.

Examples are shown below, but the present invention is not limited thereto. In the examples, parts and% shall be parts by mass or% by mass unless otherwise specified. As a 2: 1 type iron complex salt compound, in the formula of the general formula [1], A = 5-Cl group, B = hydrogen atom, X = CH₃Group, Y = unsubstituted phenyl group, J = hydrogen ion (in the formula of general formula [3], X = CH₃Group, C and D are hydrogen atom, J = hydrogen ion). In this, as impurities, in the formula of the general formula [2], A = 5-Cl group, B = hydrogen atom, X = CH₃Group, Y = unsubstituted phenyl group (in the general formula [4], X = CH₃A monoazo compound having a group (group, C and D as a hydrogen atom) was prepared so that its content was 0.9% by mass, and three types of 2: 1 type iron complex salt compounds were prepared. 5 parts of carbon black and styrene acrylic synthetic resin (manufactured by Mitsui Chemicals Co., Ltd., trade name CPR-200) are mixed in the ratio shown in the following [Table 1], mixed sufficiently, heated, melted and kneaded, cooled and crushed and classified by a conventional method. Then, a negatively charged toner having a volume average particle size of 9 ± 0.5 μm was obtained. This toner was mixed and shaken with a silicon coat carrier (manufactured by Powdertech Co., Ltd., trade name: F96-100) at a ratio of 4 to 100 parts by mass, the toner was negatively charged, and then measured with a blow-off charge measuring device. .. In this case, the content β of the monoazo compound of the general formula [2] in the 2: 1 type iron complex salt compound of the general formula [1] is 0.9% by mass wt%, and 2: of the general formula [1] in the toner. Since the addition amount α of the type 1 iron complex salt compound is 1% by mass, α × β = 0.9.

The amount α of the 2: 1 type iron complex salt compound of the general formula [1] added to the toner was set to 2% by mass, and the toner was prepared by the same method as in Example 1 for the others, and measured with a blow-off charge measuring device. .. In this case, α × β = 1.8.

The amount α of the 2: 1 type iron complex salt compound of the general formula [1] added to the toner was set to 3% by mass, and the toner was prepared by the same method as in Example 1 for the others, and measured with a blow-off charge measuring device. .. In this case, α × β = 2.7.

The monoazo compound content β of the general formula [2] in the 2: 1 type iron complex salt compound of the general formula [1] is 3.1% by mass, and the 2: 1 type iron complex salt compound of the general formula [1] in the toner. Toner was prepared in the same manner as in Example 1 except that the addition amount α was 1% by mass, and the toner was measured with a blow-off charge measuring device. In this case, α × β = 3.1.

The amount α of the 2: 1 type iron complex salt compound of the general formula [1] added to the toner was set to 2% by mass, and the toner was prepared by the same method as in Example 4 for the others, and measured with a blow-off charge measuring device. .. In this case, α × β = 6.2.

The amount α of the 2: 1 type iron complex salt compound of the general formula [1] added to the toner was set to 3% by mass, and the toner was prepared by the same method as in Example 4 for the others, and measured with a blow-off charge measuring device. .. In this case, α × β = 9.3.

The monoazo compound content β of the general formula [2] in the 2: 1 type iron complex salt compound of the general formula [1] is set to 5.3% by mass, and the 2: 1 type iron complex salt compound of the general formula [1] in the toner. Toner was prepared in the same manner as in Example 1 except that the addition amount α was 1% by mass, and the toner was measured with a blow-off charge measuring device. In this case, α × β = 5.3.

[Comparative example 1]

The monoazo compound content β of the general formula [2] in the 2: 1 type iron complex salt compound of the general formula [1] is set to 5.3% by mass, and the 2: 1 type iron complex salt compound of the general formula [1] in the toner. Toner was prepared in the same manner as in Example 1 except that the addition amount α was 2% by mass, and the toner was measured with a blow-off charge measuring device. In this case, α × β = 10.6.

[Comparative example 2]

The monoazo compound content β of the general formula [2] in the 2: 1 type iron complex salt compound of the general formula [1] is set to 5.3% by mass, and the 2: 1 type iron complex salt compound of the general formula [1] in the toner. Toner was prepared in the same manner as in Example 1 except that the addition amount α was 3% by mass, and the toner was measured with a blow-off charge measuring device. In this case, α × β = 15.9.

In addition, the time constant (τ), which is an index of charge rising property, was also calculated. The time constant (τ) is described in the Journal of the Electrophotographic Society, P307, Vol. 27, No. 3 (1988), which measures the amount of charge until reaching saturated charge with a blow-off charge amount measuring device at regular intervals. , Ln (qmax-q) was calculated by the following equation, and the relationship between time t and ln (qmax-q) was plotted on a graph to obtain the time constant (τ). (qmax-q) / (qmax-q0) = exp (-t / τ) where qmax is the saturated charge amount, q0 is the initial charge amount (here, the value when the charge time is 30 seconds), and t is each measurement. It is time, and the amount of charge at that time is q. Those with a good rise in charge have a smaller time constant. The unit of the time constant is seconds.

In addition, the environmental stability evaluation method, which also evaluated the environmental stability of charging, is in addition to the usual measurement in an environment of 25 ° C-50% RH (relative humidity), in a high temperature and high humidity environment ( Judgment was made by measuring the amount of charge at 35 ° C-85% RH). In the charge amount measurement, the developer exposed to each environment for 24 hours was sufficiently charged while being left in the environment, and the saturated charge amount was measured by a blow-off charge amount measuring device. In the two environments, the one in which the fluctuation of the charge amount was less than 20% was regarded as good (), and the one in which the fluctuation of the charge amount exceeded 20% was regarded as defective (×). The results are shown in Table 1.

<tables num="1"><img file="JP2005292823A_D0009.tif" /></tables>

From the results of [Table 1], the monoazo compound content β% by mass of the general formula [2] in the 2: 1 type iron complex salt compound of the general formula [1] and 2 of the general formula [1] in the toner. It can be seen that the toner satisfying the condition that the product of the amount of the 1: 1-type iron complex salt compound added to α mass% is 10 or less has a high charge amount, and has good charge riseability and environmental stability.

Since the negatively charged electrophotographic toner of the present invention has a specific impurity content suppressed by the impurity suppression management method at the time of toner production, a high charge amount, a quick rise of charge, and environmental stability are required. Suitable for applications. Since it does not have a nitro group in the structural formula, it is required that there is no powder explosion during toner production, or because it does not contain metals such as chromium, it produces harmful substances even if it is burned or oxidized. Suitable when not required. It is also suitable as an impurity control control method during toner production.