JP4140166B2 - Magnetic toner for developing electrostatic image and image forming method - Google Patents

Description

【０１９２】
＊珪素含有量 ：質量％
＊平均粒径 ：数平均一次粒子径（μｍ）
＊ＦｅＯ含有量：質量％
＊飽和磁化 ：７９．６ｋＡ／ｍにおける飽和磁化（Ｗｂ・ｍ／ｋｇ）
【０１９３】
【表２】

【０１９４】
〔評価（非接触現像方式）〕
評価は、ＨＰ社製レーザープリンター「ＬＪ４０００」を改造して使用した。
【０１９５】
条件を下記に示す。感光体としては積層型有機感光体を使用した。
・感光体表面電位＝−７５０Ｖ
・ＤＣバイアス ＝−６１０Ｖ
・ＡＣバイアス ＝Ｖｐ−ｐ：２７００Ｖ
・交番電界周波数＝５０００Ｈｚ
・Ｄｓｄ ＝２７０μｍ
・磁性Ｈ−Ｃｕｔ方式の薄層形成方式
・磁性トナー厚 ＝１００μｍ
・現像スリーブ ＝２０ｍｍ径のアルミニウム製円筒状基体
定着器としては圧接方式の加熱定着器を採用した。構成は下記のとおりである。
【０１９６】
テトラフルオロエチレン−パーフルオロアルキルビニルエーテル共重合体で表面を被覆した直径３０ｍｍのヒーターを中央部に内蔵した円柱状の鉄からなる上ローラーを有し、表面が同様にテトラフルオロエチレン−パーフルオロアルキルエーテル共重合体で被覆したシリコーンゴムで構成された直径３０ｍｍの下ローラーを有している。線圧は８．０Ｎ／ｃｍに設定され、ニップの幅は４．３ｍｍとした。この定着器を使用して、印字の線速を２５０ｍｍ／ｓｅｃに設定した。定着の温度は上ローラの表面温度で制御し、１８５℃の設定温度とした。なお、定着装置のクリーニング機構としてポリジフェニルシリコーン（２０℃の粘度が１００Ｐａ・ｓのもの）を含浸したウェッブ方式の供給方式を使用した。
【０１９７】
上記条件にて、画素率が４％の線画を使用し、２００００枚にわたる画像形成を行い、初期の画像と、２００００枚目後の画像とについて、各種の評価を行った。
【０１９８】
〔評価方法〕
（１）最大画像濃度
ベタ黒画像の画像濃度を測定した。測定にはマクベス反射濃度計「ＲＤ−９１８」を用いて絶対反射濃度を測定した。
【０１９９】
（２）ベタ黒画像濃度ムラ
ベタ黒画像の最大反射濃度と最小反射濃度をマクベス反射濃度計「ＲＤ−９１８」を用いて絶対反射濃度で測定し、その差を求めた。差が少ないほど、ベタ黒画像の安定性に優れているといえる。
【０２００】
なお、ベタ黒画像を印字する前に、１０ｍｍ幅の縦の黒筋スジ画像を印字した後に出力した。この結果、ベタ黒画像の濃度の差が大きいものほど、いわゆる現像ゴースト現象が発生しているものといえる。
【０２０１】
（３）カブリ濃度
印字されていない白紙について、マクベス反射濃度計「ＲＤ−９１８」を用いて２０ヶ所の絶対画像濃度を測定して平均し、白紙濃度とする。次に評価形成画像の白地部分について、同様に２０ヶ所の絶対画像濃度を測定して平均し、この平均濃度から白紙濃度を引いた値をカブリ濃度として評価した。
【０２０２】
カブリ濃度が０．０１０以下であれば、カブリは実用的に問題ないといえる。
【０２０３】
【表３】

【０２０４】
以上の様に、本発明の画像形成によれば繰り返しの画像形成によっても画質の変化が小さく、現像性および細線再現性に優れ、高画質な画像を長期に亘って安定的に形成することができる。
【０２０５】
【発明の効果】
本発明により、現像性および細線再現性に優れ、高画質な画像を長期に亘って安定的に形成することができる一成分の静電荷像現像用磁性トナーを提供することができる。
【０２０６】
又、一成分磁性現像において現像性および細線再現性に優れ、高画質な画像を長期にわたって安定的に形成することができる画像形成方法を提供することが出来る。
【図面の簡単な説明】
【図１】攪拌翼の構成が一段の反応装置を示す構成斜視図。
【図２】好ましく使用することのできる攪拌翼を備えた反応装置の一例を示す斜視図。
【図３】図２に示した反応装置の断面図。
【図４】好ましく使用することのできる攪拌翼を備えた反応装置の具体例を示す斜視図。
【図５】好ましく使用することのできる攪拌翼を備えた反応装置の具体例を示す斜視図。
【図６】好ましく使用することのできる攪拌翼を備えた反応装置の具体例を示す斜視図。
【図７】好ましく使用することのできる攪拌翼を備えた反応装置の具体例を示す斜視図。
【図８】好ましく使用することのできる攪拌翼を備えた反応装置の具体例を示す斜視図。
【図９】層流を形成させる場合に使用される反応装置の一例を示す斜視図。
【図１０】攪拌翼の形状の具体例を示す概略図。
【図１１】（ａ）は、角のないトナー粒子の投影像を示す説明図であり、（ｂ）および（ｃ）は、それぞれ角のあるトナー粒子の投影像を示す説明図。
【図１２】非接触現像方式による現像装置の一例を示す概略図。
【図１３】定着器の構成の一例を示す構成断面図。
【符号の説明】
１ 熱交換用ジャケット
２ 攪拌槽
３ 回転軸
４ 攪拌翼
４０ 下段に位置する攪拌翼
４１ 下段に位置する攪拌翼
４１１ 折り曲げ部
４２ 下段に位置する攪拌翼
４２１ スリット
４２２ 折り曲げ部
４２３ フィン
４３ 下段に位置する攪拌翼
４３１ 折り曲げ部
４３２ フィン
４４ 下段に位置する攪拌翼
４４１ 折り曲げ部
４４２ フィン
４５ 下段に位置する攪拌翼
４６ 下段に位置する攪拌翼
５０ 上段に位置する攪拌翼
５１ 上段に位置する攪拌翼
５１１ フィン
５２ 上段に位置する攪拌翼
５３ 上段に位置する攪拌翼
５４ 上段に位置する攪拌翼
５４１ 中孔部
５５ 中段に位置する攪拌翼
５６ 上段に位置する攪拌翼
６５ 上段に位置する攪拌翼
５ａ，５ｂ，５ｃ，５ｄ 攪拌翼
６ｂ，６ｃ，６ｄ 中孔部
７ 上部材料投入口
８ 下部材料投入口
９ 乱流形成部材
α 交差角
７３ 感光体
７４ 現像剤担持体
７５ スリーブ
７６ 磁石
７７ 二成分現像剤
７８ 現像剤層規制部材
７９ 現像領域
８０ 現像剤層
８１ 電源
８４ 加熱体
８５ アルミナ基板
８６ 抵抗材料
８７ 検温素子
８８ フィルム
８９ 駆動ローラー
９０ 従動ローラー
９１ 繰り出し軸
９２ 巻き取り軸
９３ 未定着トナー像
９４ 転写材
９５ 加圧ローラー
Ｄｓｄ 最小間隙[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic toner for developing an electrostatic image used for a copying machine, a printer, and the like, and an image forming method.
[0002]
[Prior art]
In a method of developing an electrostatic charge image such as an electrophotographic method to form an image, the one-component magnetic development method is widely used because the apparatus is simple and a relatively good image can be obtained.
[0003]
In this developing method, the toner is charged mainly by friction with the developing sleeve, and further charged by friction between the toners.
[0004]
In order to perform this frictional charging, the charging performance of the toner itself is an important factor. In order to improve the triboelectric chargeability, a method of adding a charge control agent to the magnetic toner, a method of using an external additive, and the like have been developed. However, the improvement in frictional charging performance is more important for small-diameter magnetic toners that support high image quality in recent years, and in a range that can be improved by the addition of simple charge control agents and external additives. It is gone.
[0005]
Further, with a magnetic toner having a reduced particle size, a development ghost is easily generated during development, and improvement of toner transportability and exchangeability is an important issue.
[0006]
Further, as another problem from the viewpoint of the conventional image forming method using one-component magnetic toner, there are problems such as a request for higher image quality of the initial image, image quality deterioration due to repeated use, and prevention of image defects. is there. For example, there are problems such as a decrease in gradation, a decrease in fine line reproducibility, a change in image density, density unevenness, fogging, and the like. A major cause of these problems is the difficulty in controlling the toner charge amount and instability.
[0007]
Since this toner charging uses frictional charging, it is extremely difficult to control and stabilize the toner. As described above, for these problems, many proposals have been made regarding binder resins, charge control agents, external additives, other additives, etc. in a one-component magnetic toner, and they are enumerated.
[0008]
However, with the improvement in performance and reliability in each step of image formation using toner for developing electrostatic image, further improvement in image quality and high durability of the one-component magnetic toner development method are required.
[0009]
[Problems to be solved by the invention]
An object of the present invention is to provide a one-component magnetic toner for developing an electrostatic charge image that is excellent in developability and fine line reproducibility and can stably form a high-quality image over a long period of time.
[0010]
Another object of the present invention is to provide an image forming method that is excellent in developability and fine line reproducibility in one-component magnetic development and can stably form a high-quality image over a long period of time.
[0011]
[Means for Solving the Problems]
  The object of the present invention is the above-mentioned claims 1 to 4.9The magnetic toner for developing an electrostatic image according to any one of the above, and the claim10-18This is achieved by adopting any one of the image forming methods.
[0012]
Hereinafter, the present invention will be described in detail. In the description of the present invention, the magnetic toner may be referred to as the toner of the present invention or simply the toner.
[0013]
In image formation over a long period of time in one-component magnetic development, a phenomenon occurs in which magnetic toner that has not been developed and remains on the developing device is repeatedly agitated on the sleeve. As a result, the toner whose charging ability is deteriorated due to the repeatedly applied stress is easily accumulated on the sleeve. In this accumulated toner, most of the reverse polarity charged toner due to charging such as mutual friction remains, and this causes problems such as fogging.
[0014]
In the present invention, it is found that the toner has a specific shape and particle size distribution, thereby suppressing the deterioration thereof, and as a result, the charging performance can be maintained over a long period of time, and a stable image can be formed. It was something that could be completed.
[0015]
Furthermore, if the toner has a uniform shape and particle size and a toner having a uniform surface property and shape, the rising of chargeability can be maintained, and problems such as image fogging can be suppressed. all right.
[0016]
As a result of studying toner particles that easily contaminate the developing sleeve and the charging member, the present inventors have found that toner particles having irregular shapes and toner having corner portions when image formation is repeated over a long period of time. The particles were found to be prone to these contaminations.
[0017]
Although the reason for this is not clear, when the toner particles are uneven in shape, the toner composition is susceptible to mechanical stress due to stirring or the like inside the developing device, and a portion to which excessive stress is applied is generated. Was transferred to the contaminated material and adhered, and the chargeability of the toner was estimated to change.
[0018]
The difference in how stress is applied also varies depending on the particle size of the toner particles, and the smaller particle size has higher adhesion than its mass, which causes contamination when subjected to stress. I found it easy. On the other hand, when the toner particle size is large, such contamination is less likely to occur, but it is susceptible to surface property fluctuations due to stress, and there is a problem that charging property fluctuations occur.
[0019]
Furthermore, regarding the occurrence of such contamination, the initial toner charge amount distribution is also important. If the charge amount distribution is wide, so-called selective development occurs in image formation, and toner particles that are difficult to develop accumulate in the developing device and developability deteriorates. As a result, there arises a problem that contamination occurs or the surface property of the toner changes to change the charging property, resulting in a weakly charged toner or a toner having a reverse polarity, resulting in a deterioration in image quality.
[0020]
As a result of examining the toner charge amount distribution, in order to make the toner charge amount distribution extremely sharp, it is necessary to control the variation in the particle size of the toner particles to be small and the shape variation to be small. It has been found. By making the toner charge amount distribution extremely sharp, even when the toner charge amount is set low, it is possible to obtain stable chargeability over a long period of time.
[0021]
  As a result of examining from the above viewpoint, the variation coefficient of the shape factor is 16% or less.The proportion of toner particles without corners is 50% by number or more,By using a toner composed of toner particles having a number variation coefficient of 27% or less in the number particle size distribution, it has been found that a high-quality image can be formed over a long period of time with excellent developability and fine line reproducibility. Claims 1 to9The first invention of the present invention has been completed.
[0022]
In addition, as a result of investigations by paying attention to the minute shape of each toner particle, the present inventors have changed the shape of the corner portion of the toner particle to become round inside the developing device, and the portion is contaminated. It was found that it was generated. For this reason, it was presumed that stress was easily applied to the corner portion, and the toner composition moved to and adhered to the contaminated material due to wear and fracture of this portion, thereby changing the chargeability of the toner.
[0023]
Further, when charge is applied to the toner particles by frictional charging, it is presumed that the charge tends to concentrate particularly at the corner portions, and the toner particles are likely to be non-uniformly charged.
[0025]
Further, it has been found that even when the toner is made to have a specific shape, the contamination by the toner composition is reduced and the charge amount distribution becomes sharp.
[0027]
In addition, as image forming methods using magnetic toner, charging is performed by utilizing frictional charging between magnetic toners and contact development is performed with the photoconductor, and the toner is ejected with the photoconductor and developer facing each other in a non-contact state. There is an image forming method including a developing step of making the image visible. This non-contact developing method does not use the frictional charging property between the toners, so that there is no occurrence of reverse polarity toner, so that the generation of so-called fringe images can be suppressed and the transfer rate can be increased. This method is preferably used as a forming method. However, in this non-contact development method, since it is non-contact, the development efficiency tends to be lower than that of contact development, and selective development due to charging property is likely to occur in repeated image formation. As a result, there is a problem that the amount of the developing toner varies and the image quality is greatly deteriorated. Furthermore, problems such as development ghost are liable to occur due to the poor replacement of the toner remaining on the developing unit.
[0028]
  As described above, the toner of the present invention has a sharp charge amount distribution and can maintain a stable chargeability over a long period of time. Therefore, the image forming method has excellent developability and fine line reproducibility. The present invention has found that a particularly great effect can be achieved that can form a high-quality image over a long period of time.10-18No. described in2The present invention has been completed.
[0029]
The “shape factor” of the toner of the present invention is represented by the following formula and indicates the degree of roundness of the toner particles.
[0030]
      Shape factor = ((maximum diameter / 2) ² × π) / projection area
  Here, the maximum diameter refers to the width of a particle that maximizes the interval between the parallel lines when the projected image of the toner particles on the plane is sandwiched between two parallel lines. The projected area refers to the area of the projected image of the toner particles on the plane.
[0031]
In the present invention, this shape factor is obtained by taking a photograph in which the toner particles are magnified 2000 times with a scanning electron microscope, and then using “SCANNING IMAGE ANALYZER” (manufactured by JEOL Ltd.) based on this photograph. It was measured by performing analysis. At this time, the shape factor of the present invention was measured by the above formula using 100 toner particles.
[0032]
The ratio of toner particles having a shape factor in the range of 1.0 to 1.6 is preferably 65% by number or more, and more preferably 70% by number or more. More preferably, the ratio of the toner particles having the shape factor in the range of 1.2 to 1.6 is 65% by number or more, and more preferably 70% by number or more.
[0033]
When the ratio of the toner particles having the shape factor in the range of 1.0 to 1.6 is 65% by number or more, the toner particles are less likely to be crushed and the contamination of the charge imparting member is reduced. Is stable.
[0034]
The ratio of the toner particles having the shape factor in the range of 1.2 to 1.6 needs to be 65% by number or more, and preferably 70% by number or more.
[0035]
The method for controlling the shape factor is not particularly limited. For example, a method in which toner particles are sprayed in a hot air stream, a method in which toner particles are repeatedly applied with mechanical energy due to impact force in a gas phase, a method in which a toner is not dissolved in a solvent and a swirl flow is applied. A method in which toner particles having a shape factor of 1.0 to 1.6 or 1.2 to 1.6 are prepared and added to a normal toner so as to fall within the scope of the present invention. is there. In addition, toner particles whose shape factor is adjusted to 1.0 to 1.6 or 1.2 to 1.6 are added to normal toner in the same manner by controlling the overall shape at the stage of preparing a so-called polymerization method toner. There is a method to prepare.
[0036]
Among the above methods, the polymerization toner is preferable because it is simple as a production method and has excellent surface uniformity as compared with the pulverized toner.
[0037]
Next, the “shape coefficient variation coefficient” of the toner of the present invention is calculated from the following equation.
Coefficient of variation (%) = (S1 / K) × 100
In the formula, S1 represents the standard deviation of the shape factor of 100 toner particles, and K represents the average value of the shape factor.
[0038]
The variation coefficient of the shape factor is 16% or less, preferably 14% or less. When the variation coefficient of the shape factor is 16% or less, voids in the transferred toner layer (powder layer) are reduced, fixing property is improved, and offset is less likely to occur. In addition, the charge amount distribution becomes sharp and the image quality is improved.
[0039]
In order to control the shape factor of the toner and the coefficient of variation of the shape factor uniformly without any lot variation, resin particles (polymer particles) constituting the toner of the present invention are prepared (polymerized), and the resin particles are melted. In the process of controlling the attachment and shape, an appropriate process end time may be determined while monitoring the characteristics of the toner particles (colored particles) being formed.
[0040]
Monitoring means that a measuring device is incorporated in-line, and process conditions are controlled based on the measurement result. In other words, in the case of a polymerization method toner that is formed by incorporating measurement such as shape in-line, for example, by associating or fusing resin particles in an aqueous medium, the shape and particle size are measured while performing sequential sampling in the fusing step. The reaction is stopped when the desired shape is obtained.
[0041]
Although it does not specifically limit as a monitoring method, The flow type particle image analyzer FPIA-2000 (made by Toa Medical Electronics Co., Ltd.) can be used. This apparatus is suitable because the shape can be monitored by performing image processing in real time while passing the sample liquid. That is, a pump or the like is used from the reaction field and is constantly monitored to measure the shape and the like, and the reaction is stopped when the desired shape is obtained.
[0042]
The number particle size distribution and the number variation coefficient of the toner of the present invention are measured by a Coulter Counter TA-II or Coulter Multisizer (manufactured by Coulter Inc.). In the present invention, a Coulter Multisizer is used, and an interface (manufactured by Nikkaki Co., Ltd.) that outputs a particle size distribution and a personal computer are connected. The aperture used in the Coulter Multisizer was 100 μm, and the volume and number of toners of 2 μm or more were measured to calculate the particle size distribution and average particle size. The number particle size distribution represents the relative frequency of the toner particles with respect to the particle size, and the number average particle size represents the median diameter in the number particle size distribution.
[0043]
The “number variation coefficient in the number particle size distribution” of the toner is calculated from the following equation.
Number variation coefficient (%) = (S2 / Dn) × 100
In the formula, S2 represents the standard deviation in the number particle size distribution, and Dn represents the number average particle size (μm).
[0044]
The number variation coefficient of the toner of the present invention is 27% or less, preferably 25% or less. When the number variation coefficient is 27% or less, the charge amount distribution becomes sharp, the transfer efficiency is increased, and the image quality is improved.
[0045]
The method for controlling the number variation coefficient in the toner of the present invention is not particularly limited. For example, a method of classifying toner particles by wind force can be used, but classification in a liquid is effective for reducing the number variation coefficient. As a method of classifying in this liquid, there is a method of separating and collecting toner particles according to a difference in sedimentation speed caused by a difference in toner particle diameter by using a centrifuge and controlling the rotation speed.
[0046]
In particular, when a toner is produced by a suspension polymerization method, a classification operation is indispensable in order to make the number variation coefficient in the number particle size distribution 27% or less. In the suspension polymerization method, it is necessary to disperse a polymerizable monomer in an oil droplet having a desired size as a toner in an aqueous medium before polymerization. That is, mechanical shearing with a homomixer or homogenizer is repeated for large oil droplets of a polymerizable monomer to reduce the oil droplets to the size of toner particles. In the method using shearing, the number particle size distribution of the obtained oil droplets is wide, and therefore the particle size distribution of the toner obtained by polymerizing the oil droplets is also wide. For this reason, classification operation is essential.
[0047]
In the toner particles of the present invention, the ratio of toner particles having no corners is required to be 50% by number or more, and this ratio is preferably 70% by number or more.
[0048]
The proportion of toner particles having no corners in the toner particles constituting the toner of the present invention is preferably 50% by number or more, and more preferably 70% by number or more.
[0049]
When the proportion of toner particles having no corners is 50% by number or more, toner particles that are easily worn and broken and toner particles having a portion where charges are concentrated are reduced, the charge amount distribution becomes sharp, and the charge is reduced. The stability is also stable and good image quality can be formed over a long period of time.
[0050]
Here, the “toner particles having no corners” means toner particles having substantially no protrusions that concentrate electric charges or protrusions that easily wear due to stress. Specifically, the following toner particles are used. Is called toner particles having no corners.
[0051]
That is, as shown in FIG. 11A, when the major axis of the toner particle T is L, a circle C having a radius (L / 10) is in contact with the peripheral line of the toner particle T at one point inside. A case where the circle C does not substantially protrude outside the toner T when the inner side is rolled is referred to as “toner particles having no corners”. “A case where the protrusion does not substantially protrude” refers to a case where the protrusion having the protruding circle is one or less. The “major diameter of toner particles” refers to the width of a particle that maximizes the interval between the parallel lines when the projected image of the toner particles on a plane is sandwiched between two parallel lines. FIGS. 11B and 11C show projection images of toner particles having corners, respectively.
[0052]
The ratio of toner particles having no corners was measured as follows. First, an enlarged photograph of the toner particles is taken with a scanning electron microscope, and further enlarged to obtain a 15,000 times photographic image. The photographic image is then measured for the presence or absence of the corners. This measurement was performed on 100 toner particles.
[0053]
A method for obtaining toner having no corners is not particularly limited. For example, as described above as a method for controlling the shape factor, a method in which toner particles are sprayed into a hot air stream, a method in which toner particles are repeatedly applied with mechanical energy by impact force in a gas phase, or a toner is dissolved. It can be obtained by adding in a solvent that does not, and applying a swirling flow.
[0054]
Further, in the polymerization toner formed by associating or fusing the resin particles, the fusing particle surface has many irregularities at the fusing stop stage, and the surface is not smooth, but the temperature in the shape control step, By making the conditions such as the number of revolutions of the stirring blade and the stirring time appropriate, a toner having no corners can be obtained. These conditions vary depending on the physical properties of the resin particles. For example, by setting the rotational speed to be higher than the glass transition temperature of the resin particles, the toner can be formed with a smooth surface and no corners.
[0055]
The toner of the present invention preferably has a number average particle diameter of 3 to 8 μm. When the toner particles are formed by a polymerization method, this particle size is determined in the toner production method described in detail later, in the concentration of the aggregating agent, the amount of organic solvent added, or the fusing time, and further the composition of the polymer itself. Can be controlled by.
[0056]
When the number average particle diameter is 3 to 8 μm, toner particles having high adhesion force that fly and adhere to the heating member and generate offset in the fixing process are reduced, and transfer efficiency is increased and halftone The image quality is improved, and the image quality of fine lines and dots is improved.
[0057]
As the toner of the present invention, when the particle size of the toner particle is D (μm), the natural logarithm lnD is taken on the horizontal axis, and the number-based particle size distribution is divided into a plurality of classes at intervals of 0.23. In the histogram shown, the sum (M) of the relative frequency (m1) of the toner particles included in the most frequent class and the relative frequency (m2) of the toner particles included in the next most frequent class after the most frequent class is 70. % Of the toner is preferable.
[0058]
When the sum (M) of the relative frequency (m1) and the relative frequency (m2) is 70% or more, the dispersion of the particle size distribution of the toner particles becomes narrow. Therefore, selective development can be performed by using the toner in the image forming process. Can be reliably suppressed.
[0059]
In the present invention, the histogram showing the particle size distribution based on the number is a natural logarithm lnD (D: particle size of individual toner particles) having a plurality of classes (0 to 0.23: 0.23) at intervals of 0.23. 0.46: 0.46-0.69: 0.69-0.92: 0.92-1.15: 1.15-1.38: 1.38-1.61: 1.61-1. 84: 1.84 to 2.07: 2.07 to 2.30: 2.30 to 2.53: 2.53 to 2.76, and so on). This histogram was created by transferring the particle size data of the sample measured by the Coulter Multisizer to the computer via the I / O unit according to the following conditions and using the particle size distribution analysis program in the computer. is there.
[0060]
Measurement condition
(1) Aperture: 100 μm
(2) Sample preparation method: Electrolyte [ISOTON R-11 (manufactured by Coulter Scientific Japan)] 50-100 ml, an appropriate amount of a surfactant (neutral detergent) was added and stirred, and a measurement sample 10-20 mg was added thereto. Add This system is prepared by dispersing for 1 minute with an ultrasonic disperser.
[0061]
The conventionally known numerical values of the toner will be described with respect to the values obtained by the above formulas according to the present invention. Needless to say, these numerical values vary depending on various requirements such as the manufacturing method.
[0062]
  In the case of pulverized toner, the proportion of toner particles having a shape factor of 1.2 to 1.6 is about 60% by number. The variation coefficient of the shape factor of this is about 20%. Further, in the pulverization method, in order to reduce the particle size while repeating the crushing, the toner particles have more corners, and the proportion of toner particles without corners is 30% by number or less.
[0063]
In the case of a toner by suspension polymerization, since it is conventionally polymerized in a laminar flow, substantially spherical toner particles are obtained. For example, in the toner described in JP-A-56-130762, the shape factor is 1 The ratio of toner particles having a diameter of 2 to 1.6 is about 20% by number, the coefficient of variation of the shape factor is about 18%, and the ratio of toner particles without corners is about 85% by number. As described above, as a method for controlling the number variation coefficient in the number particle size distribution, mechanical shearing is repeatedly performed on large oil droplets of the polymerizable monomer to reduce the oil droplets to the size of toner particles. Therefore, the distribution of the oil droplet diameter is wide, and therefore the particle size distribution of the obtained toner is wide, the number variation coefficient is as large as about 32%, and classification operation is necessary to reduce the number variation coefficient. .
[0064]
In the polymerization method toner formed by associating or fusing resin particles, for example, in the toner described in JP-A-63-186253, the ratio of toner particles having a shape factor of 1.2 to 1.6 Is about 60% by number, the coefficient of variation of the shape factor is about 18%, and the proportion of toner particles without corners is about 44% by number. Further, the particle size distribution of the toner is wide, the number variation coefficient is 30%, and classification operation is necessary to reduce the number variation coefficient.
[0065]
Furthermore, in the present invention, the chargeability can be made uniform by specifying the shape and distribution of the shape of the magnetic powder.
[0066]
The magnetic powder preferably has a number average primary particle size of 0.1 to 2 μm, preferably about 0.1 to 0.5 μm. The amount contained in the toner is 20 to 200 masses per 100 mass parts of the resin component. Part, preferably 40 to 150 parts by mass with respect to 100 parts by mass of the resin component. The number average primary particle size is calculated by measuring 500 particles using a photograph magnified 5000 times with a scanning electron microscope. The maximum major axis diameter in the horizontal direction was used as the particle diameter.
[0067]
Further, by specifying the content of silicon element as the magnetic powder, the surface is not excessively oxidized, and the charging property can be stably maintained. In particular, it is effective against changes in chargeability in a high humidity environment.
[0068]
The content of silicon element in the magnetic powder used for the magnetic toner is 0.1 to 4.0% by mass (more preferably 0.4 to 2.0% by mass) based on the iron element. One. When the content of silicon element is less than 0.1% by mass, the improvement effect on the magnetic toner (particularly the improvement in fluidity of the magnetic toner) is weak, and when the content of silicon element is more than 4.0% by mass In some cases, the silicic acid component may remain on the surface of the magnetic iron oxide more than necessary or adversely affect the magnetic properties.
[0069]
In the present invention, the silicon element content of the magnetic powder (based on the iron element) can be determined by the following method. For example, about 3 liters of deionized water is put into a 5 liter beaker and heated in a water bath so that the temperature is 45 to 50 ° C. About 25 g of magnetic iron oxide slurried with about 400 ml of deionized water is added to a 5-liter beaker along with the deionized water while being washed with about 300 ml of deionized water.
[0070]
Next, while maintaining the temperature at about 50 ° C. and the stirring speed at about 200 rpm, a special grade hydrochloric acid or a mixed acid of hydrochloric acid and hydrofluoric acid is added to start dissolution. At this time, the aqueous hydrochloric acid solution is about 3N. About 20 ml is sampled several times from the start of dissolution until it is completely dissolved and becomes transparent, and filtered through a 0.1 μm membrane filter, and the filtrate is collected. The filtrate is subjected to plasma emission spectroscopy (ICP) to quantify iron and silicon elements.
[0071]
In addition, by making the ratio of the major axis and minor axis to be within a certain range, it is possible to use spherical magnetic powder and to remove unwanted adsorption components on the surface, and to maintain stable charging properties. Can do. In this case, adsorption of a so-called conductive component can be suppressed, charge leakage can be suppressed particularly in a high humidity environment, and problems such as a decrease in concentration do not occur.
[0072]
By making the shape of the magnetic powder a 6-20 icosahedron structure, the crush resistance of the toner containing the magnetic powder can be improved, and a stable image can be formed over a long period of time. In particular, in the case of an association type toner, the cohesive force inside the toner can be improved, so there is no generation of fine powders over a long period of use, no adhesion to the developing sleeve, etc. It is possible to measure the stabilization of chargeability.
[0073]
In the present invention, when a magnetic powder having an FeO content of less than 20% by mass is used for the toner, it becomes difficult to control the toner charge amount appropriately in a low-temperature and low-humidity environment. In addition, it is difficult to sufficiently deal with such stains, and color tone control for obtaining a clear color tone as a black toner becomes difficult.
[0074]
On the other hand, when magnetic iron oxide having an FeO content exceeding 30% by mass is used for the toner, the charge amount of the toner is lowered particularly in a high humidity environment, and the image density is lowered.
[0075]
Magnetic iron oxide used in the present invention is iron sulfate (FeSO_Four) Neutralized with caustic soda (NaOH) and Fe (OH)₂After adjusting the pH to 12-13 by adjusting the alkali, it is oxidized with steam and air to obtain a magnetite slurry. In the next drying step, FeO in the magnetic iron oxide can be controlled by controlling the drying temperature and drying time using a hot air dryer. After drying, the powder is crushed to obtain magnetite powder.
[0076]
Here, the measurement of FeO in magnetic iron oxide is performed according to the following procedure.
Put 1,000 g of magnetic iron oxide in a 500 ml beaker, add 50 ml of deionized water, and then add 20 ml of special grade sulfuric acid to completely dissolve the magnetic iron oxide.
[0077]
Next, 100 ml of deionized water was added, and MnSO_Four, H₂SO_FourAnd H_ThreePO_FourMnSO consisting of (molar ratio 0.3: 2.0: 2.0)_Four10 ml of the mixed solution was added to make a total of 180 ml, and 10 ml was collected and 0.1 N KMnO was collected._FourTitrate with solution.
[0078]
DETAILED DESCRIPTION OF THE INVENTION
Toner production method
The toner of the present invention is preferably a toner obtained by polymerizing at least a polymerizable monomer in an aqueous medium, and is preferably a toner obtained by associating resin particles in an aqueous medium. Hereinafter, the method for producing the toner of the present invention will be described in detail.
[0079]
The magnetic toner in the present invention is used as a developer only by adding fine silica powder or the like as an external additive to the manufactured toner particles (sometimes referred to as colored particles) as will be described later. However, it goes without saying that other additives may be added.
[0080]
In the toner of the present invention, fine polymer particles (resin particles) are prepared by emulsion polymerization of monomers in a suspension polymerization method or in a liquid (aqueous medium) to which an emulsion of necessary additives is added. Thereafter, an organic solvent, a flocculant and the like can be added to produce the resin particles in association with each other. Here, “association” means that a plurality of the resin particles are fused, and includes cases where the resin particles and other particles (for example, magnetic particles) are fused.
[0081]
An example of the method for producing the toner of the present invention includes a magnetic monomer (also referred to as a magnetic material) in a polymerizable monomer, and, if necessary, a colorant, a release agent, a charge control agent, and a polymerization initiator. And various constituent materials are dissolved or dispersed in the polymerizable monomer using a homogenizer, a sand mill, a sand grinder, an ultrasonic disperser, or the like. The polymerizable monomer in which these various constituent materials are dissolved or dispersed is dispersed in oil droplets of a desired size as a toner in an aqueous medium containing a dispersion stabilizer using a homomixer or a homogenizer. Thereafter, the stirring mechanism is transferred to a reaction device (stirring device) which is a stirring blade described later, and the polymerization reaction is advanced by heating. After completion of the reaction, the dispersion stabilizer is removed, filtered, washed, and dried to prepare the toner of the present invention.
[0082]
In the present invention, the “aqueous medium” refers to a medium containing at least 50% by mass of water.
[0083]
Further, as a method for producing the toner of the present invention, a method of preparing by associating or fusing resin particles in an aqueous medium can also be mentioned. The method is not particularly limited, and examples thereof include methods disclosed in JP-A-5-265252, JP-A-6-329947, and JP-A-9-15904. That is, a method of associating a plurality of particles composed of resin particles and magnetic powder, or a plurality of fine particles composed of a resin and a magnetic material, in particular, after dispersing them in water using an emulsifier, the critical aggregation concentration The above flocculant is added for salting out, and at the same time, the formed polymer itself is heated and fused at a temperature higher than the glass transition temperature to gradually grow the particle size while forming fused particles. Then, a large amount of water is added to stop the particle size growth, and the shape is controlled by smoothing the particle surface while heating and stirring, and the particles are heated and dried in a fluid state while containing water. The toner of the invention can be formed. Here, a solvent that is infinitely soluble in water may be added simultaneously with the flocculant.
[0084]
As the polymerizable monomer constituting the resin, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decyl Styrene, styrene such as pn-dodecylstyrene or styrene derivatives, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, Methacrylic acid ester derivatives such as lauryl tacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, acrylic Isobutyl acid, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, acrylic acid ester derivatives such as phenyl acrylate, olefins such as ethylene, propylene, isobutylene, vinyl chloride, vinylidene chloride, odor Halogenated vinyls such as vinyl fluoride, vinyl fluoride, vinylidene fluoride, vinyl esters such as vinyl propionate, vinyl acetate, vinyl benzoate, vinyl methyl ether, vinyl ethyl ether Vinyl ethers such as vinyl, vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone, vinyl hexyl ketone, N-vinyl compounds such as N-vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidone, vinyl naphthalene, vinyl pyridine, etc. There are acrylic acid or methacrylic acid derivatives such as vinyl compounds, acrylonitrile, methacrylonitrile, acrylamide and the like. These vinyl monomers can be used alone or in combination.
[0085]
Further, it is more preferable to use a combination of monomers having an ionic dissociation group as the polymerizable monomer constituting the resin. For example, it has a substituent such as a carboxyl group, a sulfonic acid group, a phosphoric acid group as a constituent group of the monomer, specifically, acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumar Acid, maleic acid monoalkyl ester, itaconic acid monoalkyl ester, styrene sulfonic acid, allyl sulfosuccinic acid, 2-acrylamido-2-methylpropane sulfonic acid, acid phosphooxyethyl methacrylate, 3-chloro-2-acid phosphooxy And propyl methacrylate.
[0086]
Furthermore, polyfunctionality such as divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, neopentyl glycol diacrylate, etc. It is also possible to use a crosslinkable resin by using a functional vinyl.
[0087]
These polymerizable monomers can be polymerized using a radical polymerization initiator. In this case, an oil-soluble polymerization initiator can be used in the suspension polymerization method. Examples of the oil-soluble polymerization initiator include 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1′-azobis (cyclohexane-1-carboxyl). Nitriles), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azo- or diazo-based polymerization initiators such as azobisisobutyronitrile, benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate , Cumene hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide, dicumyl peroxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide, 2,2-bis- (4,4- t-butylperoxycyclohexyl) propane, tris The (t-butylperoxy) triazine peroxide polymerization initiator or a peroxide, such as and the like polymeric initiator having a side chain.
[0088]
Moreover, when using an emulsion polymerization method, a water-soluble radical polymerization initiator can be used. Examples of the water-soluble radical polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate, azobisaminodipropane acetate, azobiscyanovaleric acid and its salts, hydrogen peroxide, and the like.
[0089]
Dispersion stabilizers include tricalcium phosphate, magnesium phosphate, zinc phosphate, aluminum phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate , Bentonite, silica, alumina and the like. Furthermore, those generally used as surfactants such as polyvinyl alcohol, gelatin, methylcellulose, sodium dodecylbenzenesulfonate, ethylene oxide adduct, and higher alcohol sodium sulfate can be used as the dispersion stabilizer.
[0090]
As the resin excellent in the present invention, those having a glass transition point of 20 to 90 ° C. are preferred, and those having a softening point of 80 to 220 ° C. are preferred. The glass transition point is measured by a differential calorimetric analysis method, and the softening point can be measured by a Koka flow tester. Further, these resins preferably have a molecular weight measured by gel permeation chromatography of 1,000 to 100,000 in terms of number average molecular weight (Mn) and 2000 to 1,000,000 in terms of weight average molecular weight (Mw). Further, the molecular weight distribution is preferably such that Mw / Mn is 1.5 to 100, particularly 1.8 to 70.
[0091]
The flocculant used for associating the resin particles in an aqueous medium is not particularly limited, but those selected from metal salts are preferably used. Specifically, as a monovalent metal, for example, an alkali metal salt such as sodium, potassium or lithium, as a divalent metal, for example, an alkaline earth metal salt such as calcium or magnesium, or a divalent metal such as manganese or copper. And salts of trivalent metals such as iron and aluminum, and specific salts include sodium chloride, potassium chloride, lithium chloride, calcium chloride, zinc chloride, copper sulfate, magnesium sulfate, manganese sulfate, etc. Can be mentioned. These may be used in combination.
[0092]
These flocculants are preferably added in an amount equal to or higher than the critical aggregation concentration. The critical flocculation concentration is an index relating to the stability of the aqueous dispersion, and indicates a concentration at which flocculation occurs when a flocculant is added. This critical aggregation concentration varies greatly depending on the emulsified components and the dispersant itself. For example, it is described in Seizo Okamura et al., “Polymer Chemistry 17, 601 (1960) edited by Japan Society of Polymer Science”, and the like, and a detailed critical aggregation concentration can be obtained. As another method, a desired salt is added to the target particle dispersion at different concentrations, the ζ (zeta) potential of the dispersion is measured, and the salt concentration at which this value changes is defined as the critical aggregation concentration. You can ask for it.
[0093]
The addition amount of the flocculant of the present invention may be not less than the critical aggregation concentration, but is preferably 1.2 times or more, more preferably 1.5 times or more the critical aggregation concentration.
[0094]
As the solvent that is infinitely soluble in water that can be used together with the flocculant, a solvent that does not dissolve the formed resin is selected. Specific examples include alcohols such as methanol, ethanol, propanol, isopropanol, t-butanol, methoxyethanol, and butoxyethanol, nitriles such as acetonitrile, and ethers such as dioxane. In particular, ethanol, propanol, and isopropanol are preferable.
[0095]
The amount of the solvent that is infinitely soluble in water is preferably 1 to 100% by volume with respect to the polymer-containing dispersion added with the flocculant.
[0096]
In order to make the particle shape uniform, it is preferable to fluidly dry a slurry containing 10% by mass or more of water based on the particles after preparing and filtering colored particles. Those having a polar group therein are preferred. The reason for this is considered to be that it is particularly easy to make the shape uniform in order to exhibit the effect that the water present is somewhat swollen with respect to the polymer in which the polar group is present.
[0097]
The toner of the present invention contains at least a resin and a magnetic powder (magnetic material), but may contain a release agent, a charge control agent, or the like, which is a fixability improving agent, if necessary. Further, an external additive composed of inorganic fine particles or organic fine particles may be added to the toner particles mainly composed of the resin and the magnetic material.
[0098]
The magnetic powder is 30 to 200 parts by weight, preferably 60 to 200 parts by weight, and more preferably 70 to 150 parts by weight with respect to 100 parts by weight of the binder resin. If it is less than 30 parts by mass, the transportability is insufficient, the developer layer on the developer carrying member tends to be uneven and the image tends to be uneven, and the image density tends to decrease due to an increase in developer tribo. there were. On the other hand, when the amount exceeds 200 parts by mass, there is a tendency that a problem occurs in the fixing property.
[0099]
Further, carbon black, dyes, pigments, and the like can be arbitrarily used as the colorant, and channel black, furnace black, acetylene black, thermal black, lamp black, and the like are used as the carbon black.
[0100]
As a method for adding magnetic powder and colorant, polymer particles prepared by emulsion polymerization are added at the stage of aggregation by adding an aggregating agent, and the polymer is colored, or the monomer is polymerized. The method of adding magnetic powder and polymerizing it into colored particles can be used.
[0101]
Further, a low molecular weight polypropylene (number average molecular weight = 1500 to 9000), a low molecular weight polyethylene, or the like as a fixing property improving agent may be added.
[0102]
Similarly, various known charge control agents and those that can be dispersed in water can be used. Specific examples include nigrosine dyes, naphthenic acid or higher fatty acid metal salts, alkoxylated amines, quaternary ammonium salt compounds, azo metal complexes, salicylic acid metal salts or metal complexes thereof.
[0103]
In addition, it is preferable that the number average primary particle diameter of these charge control agent and fixability improving agent particles is about 10 to 500 nm in a dispersed state.
[0104]
In the toner of the present invention, the effect can be further exhibited by adding and using fine particles such as inorganic fine particles and organic fine particles as external additives. The reason for this is presumed that the effect can be conspicuous because the burying and detachment of the external additive can be effectively suppressed.
[0105]
As the inorganic fine particles, inorganic oxide particles such as silica, titania, and alumina are preferably used, and these inorganic fine particles are preferably hydrophobized with a silane coupling agent or a titanium coupling agent. The degree of the hydrophobizing treatment is not particularly limited, but a methanol wettability of 40 to 95 is preferable. Methanol wettability is an evaluation of wettability to methanol. In this method, 0.2 g of inorganic fine particles to be measured is weighed and added to 50 ml of distilled water in a 200 ml beaker. Methanol is slowly added dropwise from a burette whose tip is immersed in the liquid until the whole of the inorganic fine particles become wet with slow stirring. When the amount of methanol necessary to completely wet the inorganic fine particles is a (ml), the degree of hydrophobicity is calculated by the following formula.
[0106]
Hydrophobicity = (a / (a + 50)) × 100
The addition amount of the external additive is 0.1 to 5.0% by mass, preferably 0.5 to 4.0% by mass in the toner. In addition, various external additives may be used in combination.
[0107]
In the suspension polymerization method toner in which a toner component obtained by dispersing or dissolving a toner component such as a magnetic material in a so-called polymerizable monomer is suspended in an aqueous medium and then polymerized. The shape of the toner particles can be controlled by controlling the flow of the medium. That is, when a large amount of toner particles having a shape factor of 1.2 or more are formed, the flow of the medium in the reaction vessel is turbulent and the polymerization proceeds to exist in an aqueous medium in a suspended state. When the oil droplets gradually become polymerized, the oil droplets become soft particles. By colliding the particles, particle coalescence is promoted, and particles with an irregular shape are obtained. . In the case of forming substantially spherical toner particles having a shape factor of less than 1.2, substantially spherical particles can be obtained by using a laminar flow of the medium in the reaction vessel to avoid particle collision. By this method, the toner shape distribution can be controlled within the scope of the present invention.
[0108]
Reactor
FIG. 1 is a structural perspective view showing a reaction apparatus (stirring apparatus) in which a generally used stirring blade has a single-stage structure. It is a flow forming member.
[0109]
In the suspension polymerization method, a turbulent flow can be formed by using a specific stirring blade, and the shape can be easily controlled. Although it is not clear as this reason, when the structure of the stirring blade 4 as shown in FIG. 1 is one stage, the flow of the medium formed in the stirring tank 2 is a wall surface from the lower part to the upper part of the stirring tank 2. It becomes only the flow that moves along. Therefore, conventionally, a turbulent flow is generally formed by arranging a turbulent flow forming member 9 such as a wall surface of the stirring tank 2 to increase the efficiency of stirring. However, in such an apparatus configuration, although the turbulent flow is partially formed, the fluid flow acts in the direction of stagnation due to the presence of the turbulent flow. I can't control it.
[0110]
A reactor equipped with a stirring blade that can be preferably used in the suspension polymerization method will be described with reference to the drawings.
[0111]
2 and 3 are a perspective view and a cross-sectional view showing an example of the reaction apparatus, respectively. In the reaction apparatus shown in FIGS. 2 and 3, a rotating shaft 3 is vertically suspended at the center of a vertical cylindrical stirring tank 2 in which a jacket 1 for heat exchange is mounted on the outer periphery, and stirring is performed on the rotating shaft 3. A lower stirrer blade 40 disposed close to the bottom surface of the tank 2 and a stirrer blade 50 disposed further upward are provided. The upper agitating blade 50 is disposed with a crossing angle α preceding the agitating blade 40 located in the lower stage in the rotational direction. In the production of the toner of the present invention, the crossing angle α is preferably less than 90 degrees (°). The lower limit of the crossing angle α is not particularly limited, but is preferably about 5 degrees or more, and more preferably 10 degrees or more. When a three-stage stirring blade is provided, the crossing angle between adjacent stirring blades is preferably less than 90 degrees.
[0112]
By setting it as such a structure, a medium is first stirred by the stirring blade 50 arrange | positioned in the upper stage, and the flow to the lower side is formed. Next, the flow formed by the upper stirring blade 50 is further accelerated downward by the stirring blade 40 disposed in the lower stage, and a downward flow is separately formed in the stirring blade 50 itself, and the flow as a whole is increased. Presumed to be accelerated and proceed. As a result, a flow area having a large shear stress formed as a turbulent flow is formed, and it is estimated that the shape of the obtained toner particles can be controlled.
[0113]
2 and 3, arrows indicate the rotation direction, 7 is an upper material inlet, 8 is a lower material inlet, and 9 is a turbulent flow forming member for making stirring effective.
[0114]
Here, the shape of the stirring blade is not particularly limited, but it may be a rectangular plate, a notch in a part of the blade, one or more holes in the center, and a so-called slit. Can be used. Specific examples of these are shown in FIG. The stirring blade 5a shown in FIG. 10 (a) has no medium hole, the stirring blade 5b shown in FIG. 10 (b) has a large middle hole 6b in the center, and the stirring blade 5c shown in FIG. 10 (c). Has a horizontally elongated hole 6c (slit), and the stirring blade 5d shown in FIG. 4D has a vertically elongated hole 6d (slit). In addition, when a three-stage stirring blade is provided, the middle hole formed in the upper stirring blade and the middle hole formed in the lower stirring blade may be the same, even if they are different. There may be.
[0115]
4 to 8 are perspective views showing specific examples of a reactor equipped with a stirring blade that can be preferably used. In FIGS. 4 to 8, 1 is a jacket for heat exchange, and 2 is a stirring device. A tank, 3 is a rotating shaft, 7 is an upper material inlet, 8 is a lower material inlet, and 9 is a turbulent flow forming member.
[0116]
In the reaction apparatus shown in FIG. 4, a bent portion 411 is formed on the stirring blade 41, and a fin (projection) 511 is formed on the stirring blade 51.
[0117]
In addition, when the bending part is formed in the stirring blade, it is preferable that a bending angle is 5-45 degrees.
[0118]
In the stirring blade 42 constituting the reaction apparatus shown in FIG. 5, a slit 421 is formed, and a bent portion 422 and fins 423 are formed.
[0119]
In addition, the stirring blade 52 which comprises the said reaction apparatus has a shape similar to the stirring blade 50 which comprises the reaction apparatus shown in FIG.
[0120]
Bending portions 431 and fins 432 are formed on the stirring blade 43 constituting the reaction apparatus shown in FIG.
[0121]
In addition, the stirring blade 53 which comprises the said reaction apparatus has the shape similar to the stirring blade 50 which comprises the reaction apparatus shown in FIG.
[0122]
Bending portions 441 and fins 442 are formed on the stirring blade 44 constituting the reaction apparatus shown in FIG.
[0123]
In addition, the stirring blade 54 constituting the reaction apparatus has a middle hole portion 541 formed at the center.
[0124]
The reaction apparatus shown in FIG. 8 is provided with a three-stage stirring blade including a stirring blade 45 (lower stage), a stirring blade 55 (middle stage), and a stirring blade 65.
[0125]
The stirring blade having a configuration including the bent portion 451 and the upper or lower protrusion (fin) 452 effectively generates turbulent flow.
[0126]
The gap between the upper and lower stirring blades having the above-described configuration is not particularly limited, but it is preferable to have at least a gap between the stirring blades. Although the reason for this is not clear, it is considered that the stirring efficiency is improved because a medium flow is formed through the gap. However, the gap has a width of 0.5 to 50%, preferably 1 to 30% of the liquid level in the stationary state.
[0127]
Further, the size of the stirring blade is not particularly limited, but the total height of all the stirring blades is 50% to 100%, preferably 60% to 95% of the liquid surface height in the stationary state. is there.
[0128]
Moreover, an example of the reaction apparatus used when forming a laminar flow in suspension polymerization method is shown in FIG. This reaction apparatus is characterized in that a turbulent flow forming member (an obstacle such as a baffle plate) is not provided.
[0129]
The agitating blade 46 and the agitating blade 56 constituting the reaction apparatus shown in FIG. 9 have the same shape and crossing angle α as the agitating blade 40 and the agitating blade 50 constituting the reaction apparatus shown in FIG. . In FIG. 9, 1 is a heat exchange jacket, 2 is a stirring tank, 3 is a rotating shaft, 7 is an upper material inlet, and 8 is a lower material inlet.
[0130]
In addition, as a reaction apparatus used when forming a laminar flow, it is not limited to what is shown by FIG.
[0131]
Further, the shape of the stirring blades constituting such a reactor is not particularly limited as long as it does not form turbulent flow, but is preferably formed by a continuous surface such as a rectangular plate shape, and has a curved surface. You may do it.
[0132]
On the other hand, in a polymerization method toner that associates or fuses resin particles in an aqueous medium, by controlling the flow and temperature distribution of the medium in the reaction vessel at the fusing stage, and further in the shape control step after fusing. By controlling the heating temperature, the number of rotations of stirring, and the time, the shape distribution and shape of the entire toner can be arbitrarily changed.
[0133]
That is, in the polymerization method toner that associates or fuses the resin particles, the flow in the reaction apparatus is made into a laminar flow, and the agitation step and the agitation tank that can make the internal temperature distribution uniform are used. By controlling the temperature, the number of rotations, and the time in the shape control step, it is possible to form a toner having a desired shape factor and uniform shape distribution. The reason for this is that if the laminar flow is fused in a place where the laminar flow is formed, strong stress is not applied to the particles (aggregation or agglomerated particles) in which aggregation and fusion proceed, and in laminar flow where the flow is accelerated It is estimated that this is because the shape distribution of the fused particles becomes uniform as a result of the uniform temperature distribution in the stirring tank. Further, the fused particles gradually become spherical by heating and stirring in the subsequent shape control step, and the shape of the toner particles can be arbitrarily controlled.
[0134]
As the stirring blade and the stirring tank used in the production of the polymerization toner for associating or fusing the resin particles, those similar to the case of forming a laminar flow in the suspension polymerization method described above can be used. 9 can be used. It is characterized in that no obstacle such as a baffle plate that forms a turbulent flow is provided in the stirring tank. As for the configuration of the stirring blade, like the stirring blade used in the above-described suspension polymerization method, the upper stirring blade is disposed with a crossing angle α preceding the lower stirring blade in the rotational direction. In addition, a multistage configuration is preferable.
[0135]
The shape of the stirring blade is not particularly limited as long as it does not form a turbulent flow as long as it does not form a turbulent flow as in the case of forming a laminar flow in the above-described suspension polymerization method. Those formed by a continuous surface, such as a rectangular plate shape, are preferable, and may have a curved surface.
[0136]
Development method
The developing method in which the toner of the present invention can be used is not particularly limited. However, since the toner of the present invention has a sharp charge amount distribution, it is more effective when applied to a non-contact developing system. That is, in the non-contact development method, the change in the development electric field is large, so that a slight change in charging acts on the development itself. However, since the toner of the present invention has a sharp charge amount distribution, there is little change in charge and a stable charge amount can be secured, so that a stable image can be formed over a long period of time in the non-contact development method. it can.
Configuration of developer carrier
The developer carrying member used in the present invention is composed of a substrate such as cylindrical aluminum, and may have a coating layer covering the substrate.
[0137]
The developer carrying member preferably has an appropriate roughness for conveying magnetic toner. The roughness of the developer carrying member of the present invention is 0.2 to 4.5 μm, preferably 0.4 to 3.5 μm, as center line average roughness (hereinafter referred to as Ra). If the surface roughness is less than 0.2 μm, the toner transportability may be reduced and a sufficient image density may not be obtained. If the surface roughness exceeds 4.5 μm, the toner transport amount becomes too large and the toner chargeability is poor. It will be enough.
[0138]
Here, the image forming method of the present invention is characterized in that it includes a developing step by a non-contact developing method performed using the toner of the present invention, a transferring step, and a fixing step.
[0139]
The non-contact development method is a method in which the developer layer formed on the developer carrying member (developer conveying member) and the photoconductor do not contact each other, and the developer layer is a thin layer in order to constitute this development method. Is preferably formed. In this method, a developer layer having a thickness of 20 to 500 μm is formed in the developing region on the surface of the developer carrying member, and the gap between the photosensitive member and the developer carrying member is larger than the developer layer. The thin layer is formed by a magnetic blade using magnetic force, a method of pressing a developer layer regulating rod on the surface of the developer carrying member, or the like. Further, there is a method of regulating the developer layer by bringing a urethane blade, a phosphor bronze plate or the like into contact with the surface of the developer carrying member. The pressing force of the pressing restricting member is preferably 10 to 150 N / mm. When the pressing force is small, the regulation force is insufficient, and thus the conveyance is likely to be unstable. On the other hand, when the pressing force is large, the stress on the developer is increased, and the durability of the developer is likely to be lowered. A preferable range is 30 to 100 N / mm. The gap between the developer carrying member and the photoreceptor surface must be larger than the developer layer. Further, when a developing bias is applied during development, either a method of applying only a DC component or a method of applying an AC bias may be used.
[0140]
In the present invention, it is preferable to apply an alternating electric field between the developer carrying member (developer conveying member) and the electrostatic latent image holding member (photosensitive member). By applying this alternating electric field, it is possible to fly the toner effectively. The conditions for this alternating electric field are preferably that the AC frequency f is 200 to 8000 Hz and the AC voltage Vp-p is 500 to 3000 V. When this alternating electric field is used, it is necessary that the toner has a uniform charging property. That is, when there is a distribution of chargeability between toners, the effect of pulling back weakly chargeable toner or the like due to the alternating electric field is offset, and as a result, the effect of improving image quality is reduced.
[0141]
As the developer carrying member used in the present invention, a member having a magnet built in the carrying member is often used, and the developer carrying surface (sleeve) rotates to convey the developer to the developing area. To do. The sleeve is made of aluminum, aluminum whose surface is oxidized, or stainless steel.
[0142]
The developer carrying member preferably has a diameter of 10 to 40 mm. When the diameter is small, mixing of the developer is insufficient, making it difficult to ensure sufficient mixing to impart sufficient charge to the toner, and when the diameter is large, the centrifugal force on the developer increases. Prone to toner scattering problem.
[0143]
Hereinafter, an example of the non-contact development method will be described with reference to FIG.
FIG. 12 is a schematic view of a non-contact developing type developing unit that can be suitably used in the image forming method of the present invention, wherein 73 is a photosensitive member, 74 is a developer carrier, 75 is a sleeve, 76 is a magnet, and 77 is A developer containing the toner of the present invention, 78 is a developer layer regulating member, 79 is a development region, 80 is a developer layer, and 81 is a power source for forming an alternating electric field.
[0144]
The developer 77 containing the toner of the present invention is carried by the magnetic force of the developer carrying member 74 having a magnet 76 therein, and is conveyed to the developing region 79 by the movement of the sleeve 75. During the conveyance, the thickness of the developer layer 80 is regulated by the developer layer regulating member 78 so that the developer layer 80 does not come into contact with the photoreceptor 73 in the development region 79.
[0145]
The minimum gap (Dsd) of the development region 79 is larger than the thickness of the developer layer 80 transported to that region (preferably transported by a layer of about 50 to 300 μm), for example, 100 to 1000 μm (preferably 100 to 100 μm). About 500 μm).
[0146]
The power source 81 is a power source for forming an alternating electric field, and preferably an alternating current having a frequency of 200 to 8000 Hz and a voltage of 500 to 3000 Vp-p. The power supply 81 may have a configuration in which direct current is added in series with alternating current as necessary. In that case, the DC voltage is preferably 300 to 800V.
[0147]
In the image forming method of the present invention, after the development step, the image is fixed in the fixing step after being transferred to a transfer material (also referred to as an image support, usually referred to as transfer paper for plain paper).
[0148]
A preferred fixing method used in the present invention is a so-called contact heating method. In particular, examples of the contact heating method include a heat pressure fixing method, a heat roller fixing method, and a pressure heating fixing method in which fixing is performed by a rotating pressure member including a fixedly arranged heating body.
[0149]
In the heat roller fixing method, in many cases, an upper roller having a heat source inside a metal cylinder composed of iron, aluminum or the like whose surface is coated with tetrafluoroethylene or polytetrafluoroethylene-perfluoroalkoxy vinyl ether copolymers, etc. And a lower roller made of silicone rubber or the like. A typical example of the heat source is one having a linear heater and heating the surface temperature of the upper roller to about 120 to 200 ° C. In the fixing unit, pressure is applied between the upper roller and the lower roller, and the lower roller is deformed to form a so-called nip. The nip width is 1 to 10 mm, preferably 1.5 to 7 mm. The fixing linear velocity is preferably 40 mm / sec to 600 mm / sec. If the nip is narrow, heat cannot be uniformly applied to the toner, and uneven fixing occurs. On the other hand, when the nip width is wide, the melting of the resin is promoted, and the problem of excessive fixing offset occurs.
[0150]
A fixing cleaning mechanism may be provided for use. As this method, a method of supplying silicone oil to the upper roller or film for fixing, or a method of cleaning with a pad, roller, web or the like impregnated with silicone oil can be used.
[0151]
Next, a method for fixing by a rotating pressure member including a fixedly arranged heating body used in the present invention will be described.
[0152]
This fixing method is a method in which pressure fixing is carried out by a fixedly arranged heating body and a pressure member that is opposed to the heating body and presses the transfer material in close contact with the heating body through a film.
[0153]
In this press-contact fixing device, the heating body has a smaller heat capacity than a conventional heating roller, and has a line-shaped heating portion in a direction perpendicular to the passing direction of the transfer material. 300 ° C.
[0154]
The pressure contact fixing is a method of fixing an unfixed toner image against a heating source, such as a method in which a transfer material with unfixed toner is passed between a heating member and a pressure member as is usually used. is there. In this way, since heating is performed quickly, the fixing speed can be increased. However, temperature control is difficult, and the toner remains attached to a portion directly pressed against unfixed toner such as a surface portion of the heating source. There are also problems that toner offset is likely to occur and that the transfer material is likely to fail such as winding around the fixing device.
[0155]
In this fixing method, the low-heat capacity line-shaped heating element fixedly supported by the apparatus has a thickness of 0.2 to 5.0 mm, more preferably 0.5 to 3.5 mm, a width of 10 to 15 mm, and a longitudinal length. A 240-400 mm alumina substrate is coated with a resistance material at 1.0-2.5 mm and is energized from both ends.
[0156]
The energization is a pulse waveform with a period of 15 to 25 msec with a DC of 100 V, and is changed to a pulse width corresponding to the temperature / energy release amount controlled by the temperature sensor. In the low heat capacity line-shaped heating element, when the temperature T1 is detected by the temperature sensor, the surface temperature T2 of the film facing the resistance material is lower than T1. Here, T1 is preferably 120 to 220 ° C, and the temperature of T2 is preferably 0.5 to 10 ° C lower than the temperature of T1. Further, the film material surface temperature T3 at the portion where the film peels from the toner surface is substantially equal to T2. The film moves in the direction of the arrow in FIG. 13 (a) in contact with the heating body whose energy and temperature are controlled in this way. What is used as these fixing films is a heat-resistant film having a thickness of 10 to 35 μm, such as polyester, polyperfluoroalkoxy vinyl ether, polyimide, polyetherimide, and in many cases, a conductive material is added to fluororesin such as Teflon. It is an endless film in which a release agent layer is coated by 5 to 15 μm.
[0157]
For driving the film, a driving force and tension are applied by a driving roller and a driven roller, and the film is transported in the direction of the arrow without wrinkles or twists. The linear velocity as the fixing device is preferably 40 to 600 mm / sec.
[0158]
The pressure roller has a rubber elastic layer having high releasability such as silicone rubber, and is pressure-bonded to the heating body through a film material at a total pressure of 20 to 300 N, and is pressed and rotated.
[0159]
Moreover, although the example using an endless film was demonstrated above, as shown in FIG.13 (b), you may use the film material of a end using the delivery axis | shaft and take-up axis | shaft of a film sheet. Furthermore, it may be a simple cylinder having no driving roller or the like inside.
[0160]
The fixing device may be used with a cleaning mechanism. As a cleaning method, a method of supplying various silicone oils to the fixing film, or a method of cleaning with a pad, roller, web or the like impregnated with various silicone oils is used.
[0161]
As the silicone oil, polydimethylsiloxane, polymethylphenylsiloxane, polydiphenylsiloxane, or the like can be used. Furthermore, siloxane containing fluorine can also be suitably used.
[0162]
Next, FIG. 13 shows an example of a sectional view of the fixing device.
In FIG. 13 (a), 84 is a low heat capacity line-shaped heating element fixedly supported by the apparatus. As an example, a resistance material 86 is applied to an alumina substrate 85 having a height of 1.0 mm, a width of 10 mm, and a longitudinal length of 240 mm. Is applied to a width of 1.0 mm and is energized from both ends in the longitudinal direction.
[0163]
The energization is, for example, DC100V and is usually a pulse waveform with a cycle of 20 msec, and is controlled by a signal from the temperature measuring element 87 and kept at a predetermined temperature. For this reason, the pulse width is changed according to the amount of energy released, and the range is, for example, 0.5 to 5 msec.
[0164]
The transfer material 94 carrying the unfixed toner image 93 is brought into contact via the film 88 moving to the heating body 84 controlled in this way, and the toner is thermally fixed.
[0165]
The film 88 used here moves without wrinkles while being tensioned by the driving roller 89 and the driven roller 90. Reference numeral 95 denotes a pressure roller having a rubber elastic layer formed of silicone rubber or the like, and pressurizes the heating body through a film with a total pressure of 40 to 200 N. The unfixed toner image 93 on the transfer material 94 is guided to the fixing unit by the entrance guide 96, and a fixed image is obtained by the heating described above.
[0166]
The endless belt has been described above. However, as shown in FIG. 13B, the film sheet feeding shaft 91 and the take-up shaft 92 are used, and the fixing film may be a terminal film.
[0167]
【Example】
EXAMPLES Next, although an Example demonstrates this invention concretely, this invention is not limited by this.
[0168]
(Toner Production Example 1: Example of emulsion polymerization association method)
0.90 kg of sodium n-dodecyl sulfate and 10.0 liters of pure water were added and dissolved by stirring. To this solution, magnetic powder (saturation magnetization at 79.6 kA / m 8.3 × 10^-Five(Wb · m / kg, silicon element content 1.7 mass%, average particle size 0.22 μm, FeO content 26.1 mass%, ratio of major axis to minor axis = 0.82, octahedral structure) After gradually adding 0 kg, the mixture was stirred well for 1 hour, and then continuously dispersed for 20 hours using a sand grinder (medium type disperser). This is referred to as “colorant dispersion 1”.
[0169]
A solution composed of 0.055 kg of sodium dodecylbenzenesulfonate and 4.0 liters of ion-exchanged water is referred to as “anionic surfactant solution A”.
[0170]
A solution composed of 0.014 kg of nonylphenol polyethylene oxide 10 mol adduct and 4.0 liters of ion-exchanged water is referred to as “nonionic surfactant solution B”.
[0171]
A solution obtained by dissolving 238 g of potassium persulfate in 12.0 liters of ion-exchanged water is referred to as “initiator solution C”.
[0172]
A GL (glass lining) reaction kettle with a volume of 100 liters equipped with a temperature sensor, a condenser tube, and a nitrogen introducing device was added to a WAX emulsion (a polypropylene emulsion having a number average molecular weight of 3000: number average primary particle size = 120 nm / solid content concentration = 29. 9%) 3.41 kg, the total amount of “anionic surfactant solution A” and the total amount of “nonionic surfactant solution B” were added, and stirring was started. Subsequently, 44.0 liters of ion exchange water was added.
[0173]
Heating was started and when the liquid temperature reached 75 ° C., the entire amount of “Initiator Solution C” was added dropwise. Thereafter, while controlling the liquid temperature to 75 ° C. ± 1 ° C., a solution consisting of 12.1 kg of styrene, 2.70 kg of n-butyl acrylate, 1.14 kg of methacrylic acid, and 550 g of t-dodecyl mercaptan was added dropwise. . After completion of the dropwise addition, the liquid temperature was raised to 80 ° C. ± 1 ° C. and stirring was performed for 6 hours. Next, the liquid temperature was cooled to 40 ° C. or less, stirring was stopped, and filtration was performed with a pole filter to obtain a latex. This is designated as “Latex-A”.
[0174]
The glass transition temperature of the resin particles in Latex-A was 58 ° C., the softening point was 119 ° C., the molecular weight distribution was weight average molecular weight = 13,000 and the mass average particle size was 115 nm.
[0175]
A solution prepared by dissolving 0.055 kg of sodium dodecylbenzenesulfonate in 4.0 liters of ion-exchanged pure water is referred to as “anionic surfactant solution D”.
[0176]
Further, a solution obtained by dissolving 0.014 kg of nonylphenol polyethylene oxide 10 mol adduct in 4.0 liters of ion-exchanged water is referred to as “nonionic surfactant solution E”.
[0177]
A solution obtained by dissolving 200 g of potassium persulfate (manufactured by Kanto Chemical Co., Ltd.) in 12.0 liters of ion-exchanged water is referred to as “initiator solution F”.
[0178]
A WAX emulsion (a polypropylene emulsion with a number average molecular weight of 3000: number average primary particle size = 120 nm / solid content concentration of 29.9%) is added to a 100 liter GL reaction kettle equipped with a temperature sensor, a cooling pipe, a nitrogen introducing device and a comb baffle. 3.41 kg, the total amount of “anionic surfactant solution D” and the total amount of “nonionic surfactant solution E” were added, and stirring was started.
[0179]
Next, 44.0 liters of ion exchange water was added. Heating was started, and when the liquid temperature reached 70 ° C., “initiator solution F” was added. Subsequently, a solution prepared by previously mixing 11.0 kg of styrene, 4.00 kg of n-butyl acrylate, 1.04 kg of methacrylic acid, and 9.0 g of t-dodecyl mercaptan was dropped. After completion of the dropwise addition, the liquid temperature was controlled at 72 ° C. ± 2 ° C., and the mixture was heated and stirred for 6 hours. Furthermore, the liquid temperature was raised to 80 ° C. ± 2 ° C., and the mixture was heated and stirred for 12 hours. The liquid temperature was cooled to 40 ° C. or lower, and stirring was stopped. The filtrate is filtered through a pole filter, and this filtrate is designated as “Latex-B”.
[0180]
The glass transition temperature of the resin particles in Latex-B was 59 ° C., the softening point was 133 ° C., the molecular weight distribution was weight average molecular weight = 245,000, and the mass average particle size was 110 nm.
[0181]
A solution obtained by dissolving 5.36 kg of sodium chloride as a salting-out agent in 20.0 liters of ion-exchanged water is referred to as “sodium chloride solution G”.
[0182]
A solution obtained by dissolving 1.00 g of a fluorine-based nonionic surfactant in 1.00 liter of ion-exchanged water is referred to as “nonionic surfactant solution H”.
[0183]
A 100 liter SUS reaction kettle equipped with a temperature sensor, cooling pipe, nitrogen introduction device, particle size and shape monitoring device (reaction device having the configuration shown in FIG. 9, crossing angle α is 25 °) was prepared as described above. Latex-A = 20.0 kg, latex-B = 5.2 kg, colorant dispersion 1 = 6.1 kg and ion-exchanged water 20.0 kg were added and stirred. Subsequently, it heated at 40 degreeC and the sodium chloride solution G and the nonionic surfactant solution H were added in this order. Then, after standing for 10 minutes, the temperature rise was started, the temperature was raised to a liquid temperature of 85 ° C. in 60 minutes, and the particles were heated and stirred at 85 ± 2 ° C. for 0.5 to 3 hours while being salted out / fused. Diameter growth. Next, 2.1 liters of pure water was added to stop the particle size growth.
[0184]
The fused particle dispersion prepared above was placed in a 5-liter reaction vessel (reaction apparatus having the configuration shown in FIG. 9, crossing angle α is 20 °) equipped with a temperature sensor, a cooling pipe, and a particle size and shape monitoring device. 5.0 kg was added, and the shape was controlled by heating and stirring at a liquid temperature of 85 ° C. ± 2 ° C. for 0.5 to 15 hours. Then, it cooled to 40 degrees C or less, and stopped stirring. Next, using a centrifugal separator, classification is performed in the liquid by a centrifugal sedimentation method, followed by filtration through a sieve having an opening of 45 μm, and this filtrate is used as an association liquid. Subsequently, wet cake-like non-spherical particles were collected by filtration from the associating liquid using Nutsche. Thereafter, it was washed with ion exchange water. The non-spherical particles were dried at a suction air temperature of 60 ° C. using a flash jet dryer and then dried at a temperature of 60 ° C. using a fluidized bed dryer. To 100 parts by mass of the obtained colored particles, 1 part by mass of silica fine particles was externally added and mixed with a Henschel mixer to obtain a magnetic toner by an emulsion polymerization association method.
[0185]
In the monitoring of the salting-out / fusion stage and the shape control process, by controlling the number of revolutions of stirring and the heating time, the coefficient of variation of the shape and the shape factor is controlled, and further the particle size and particle size distribution by subclassification. The magnetic toners 1 to 5 comprising toner particles having specific shape characteristics and particle size distribution characteristics were obtained by arbitrarily adjusting the coefficient of variation. The magnetic powder was changed as shown in the table.
[0186]
(Toner Production Example 6: Example of suspension polymerization method)
165 g of styrene, 35 g of n-butyl acrylate, magnetic powder (saturation magnetization at 79.6 kA / m 8.3 × 10^-FiveWb · m / kg, silicon element content 0.7 mass%, average particle size 0.20 μm, FeO content 25.1%, ratio of major axis to minor axis = 0.91, spherical structure) 130 g, di- 2 g of a t-butyl salicylic acid metal compound, 8 g of a styrene-methacrylic acid copolymer and 20 g of paraffin wax (mp = 70 ° C.) were heated to 60 ° C. and stirred with a sand grinder to disperse the magnetic powder. To this, 10 g of 2,2′-azobis (2,4-valeronitrile) as a polymerization initiator was added and dissolved to prepare a polymerizable monomer composition. Next, 450 g of 0.1 M sodium phosphate aqueous solution was added to 710 g of ion exchange water, and 68 g of 1.0 M calcium chloride was gradually added while stirring at 13,000 rpm with a TK homomixer to prepare a suspension in which tricalcium phosphate was dispersed. did. The polymerizable monomer composition was added to this suspension, and stirred at 10,000 rpm for 20 minutes with a TK homomixer to granulate the polymerizable monomer composition. Then, using the reaction apparatus (crossing angle (alpha) is 45 degrees) of the structure shown in FIG. 2, it was made to react for 5 to 15 hours at 75-95 degreeC. Tricalcium phosphate was dissolved and removed with hydrochloric acid, and then classified in a liquid by centrifugal sedimentation using a centrifugal separator, and then filtered, washed and dried. To 100 parts by mass of the obtained colored particles, 1 part by mass of silica fine particles was externally added and mixed with a Henschel mixer to obtain a toner by a suspension polymerization method.
[0187]
Monitoring is performed during the polymerization, and the variation coefficient of the shape and shape factor is controlled by controlling the liquid temperature, the number of rotations of stirring, and the heating time. Furthermore, the variation coefficient of the particle size and particle size distribution is arbitrarily determined by classification in the liquid. To obtain magnetic toners 6 to 8 composed of toner particles having specific shape characteristics and particle size distribution characteristics.
[0188]
(Toner Production Example 9: Example of suspension polymerization method)
In Toner Production Example 5, the reaction apparatus having the configuration shown in FIG. 9 (crossing angle α is 15 °) was used, and the classification in liquid using a centrifuge was not performed. A magnetic toner 9 composed of toner particles having specific shape characteristics and particle size distribution characteristics was obtained.
[0189]
(Toner Production Example 10: Example of grinding method)
100 kg of styrene-n-butyl acrylate copolymer resin and magnetic powder (saturation magnetization at 79.6 kA / m 8.3 × 10^-FiveWb · m / kg, silicon element content 1.6 mass%, average particle size 0.19 μm, FeO content 27.1 mass%, ratio of major axis to minor axis = 0.85, octahedral structure) 60 kg And 4 parts by mass of polypropylene are premixed with a Henschel mixer, melt kneaded with a twin screw extruder, coarsely pulverized with a hammer mill, and pulverized with a jet type pulverizer. Were dispersed in a hot air stream of a spray dryer (at 200 to 300 ° C. for 0.05 seconds) to obtain particles whose shape was adjusted. These particles were repeatedly classified with an air classifier until the desired particle size distribution was obtained. To 100 parts by mass of the obtained colored particles, 1 part by mass of silica fine particles was externally added and mixed with a Henschel mixer to obtain a toner by a pulverization method.
[0190]
  In this way, the magnetic toner 1 composed of toner particles having specific shape characteristics and particle size distribution characteristics, in which the shape and shape coefficient variation coefficient are controlled and the particle diameter and particle size distribution coefficient are adjusted.0Obtained.
[0191]
[Table 1]

[0192]
* Silicon content: mass%
* Average particle size: Number average primary particle size (μm)
* FeO content: mass%
* Saturation magnetization: Saturation magnetization at 79.6 kA / m (Wb · m / kg)
[0193]
[Table 2]

[0194]
[Evaluation (Non-contact development method)]
For the evaluation, a laser printer “LJ4000” manufactured by HP was modified and used.
[0195]
The conditions are shown below. As the photoconductor, a laminated organic photoconductor was used.
-Photoconductor surface potential = -750V
・ DC bias = -610V
AC bias = Vp-p: 2700V
・ Alternating electric field frequency = 5000 Hz
・ Dsd = 270 μm
・ Thin layer formation method of magnetic H-Cut method
-Magnetic toner thickness = 100 μm
・ Development sleeve = 20 mm diameter aluminum cylindrical substrate
A pressure contact type heat fixing device was adopted as the fixing device. The configuration is as follows.
[0196]
It has an upper roller made of cylindrical iron with a 30 mm diameter heater coated in the center with a surface coated with a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, and the surface is similarly tetrafluoroethylene-perfluoroalkyl ether It has a lower roller made of silicone rubber coated with a copolymer and 30 mm in diameter. The linear pressure was set to 8.0 N / cm, and the nip width was 4.3 mm. Using this fixing device, the linear speed of printing was set to 250 mm / sec. The fixing temperature was controlled by the surface temperature of the upper roller, and was set to a set temperature of 185 ° C. Note that a web-type supply system impregnated with polydiphenyl silicone (having a viscosity of 100 Pa · s at 20 ° C.) was used as a cleaning mechanism of the fixing device.
[0197]
Under the above conditions, using a line drawing with a pixel rate of 4%, image formation was performed on 20000 sheets, and various evaluations were performed on the initial image and the image after the 20000th sheet.
[0198]
〔Evaluation methods〕
(1) Maximum image density
The image density of a solid black image was measured. The absolute reflection density was measured using a Macbeth reflection densitometer “RD-918”.
[0199]
(2) Solid black image density unevenness
The maximum reflection density and the minimum reflection density of a solid black image were measured with an absolute reflection density using a Macbeth reflection densitometer “RD-918”, and the difference was obtained. It can be said that the smaller the difference, the better the stability of the solid black image.
[0200]
Before printing a solid black image, a vertical black streak image having a width of 10 mm was printed and output. As a result, it can be said that the so-called development ghost phenomenon occurs as the density difference of the solid black image increases.
[0201]
(3) fog density
About the blank paper which is not printed, absolute image density of 20 places is measured using the Macbeth reflection densitometer “RD-918”, and it is set as the blank paper density. Next, the absolute image density at 20 locations was similarly measured and averaged for the white background portion of the evaluation formed image, and the value obtained by subtracting the white paper density from this average density was evaluated as the fog density.
[0202]
If the fog concentration is 0.010 or less, it can be said that fog is practically no problem.
[0203]
[Table 3]

[0204]
As described above, according to the image formation of the present invention, the change in the image quality is small even by repeated image formation, and it is excellent in developability and fine line reproducibility and can stably form a high-quality image over a long period of time. it can.
[0205]
【The invention's effect】
According to the present invention, it is possible to provide a one-component magnetic toner for developing an electrostatic charge image that is excellent in developability and fine line reproducibility and can stably form a high-quality image over a long period of time.
[0206]
In addition, it is possible to provide an image forming method that is excellent in developability and fine line reproducibility in one-component magnetic development and can stably form a high-quality image over a long period of time.
[Brief description of the drawings]
FIG. 1 is a structural perspective view showing a reaction apparatus having a single-stage stirring blade.
FIG. 2 is a perspective view showing an example of a reaction apparatus equipped with a stirring blade that can be preferably used.
FIG. 3 is a cross-sectional view of the reaction apparatus shown in FIG.
FIG. 4 is a perspective view showing a specific example of a reactor equipped with a stirring blade that can be preferably used.
FIG. 5 is a perspective view showing a specific example of a reactor equipped with a stirring blade that can be preferably used.
FIG. 6 is a perspective view showing a specific example of a reactor equipped with a stirring blade that can be preferably used.
FIG. 7 is a perspective view showing a specific example of a reactor equipped with a stirring blade that can be preferably used.
FIG. 8 is a perspective view showing a specific example of a reactor equipped with a stirring blade that can be preferably used.
FIG. 9 is a perspective view showing an example of a reaction apparatus used when a laminar flow is formed.
FIG. 10 is a schematic view showing a specific example of the shape of a stirring blade.
FIGS. 11A and 11B are explanatory diagrams showing projected images of toner particles having no corners, and FIGS. 11B and 11C are explanatory diagrams showing projected images of toner particles having corners. FIGS.
FIG. 12 is a schematic diagram illustrating an example of a developing device using a non-contact developing method.
FIG. 13 is a structural cross-sectional view illustrating an example of a configuration of a fixing device.
[Explanation of symbols]
1 Heat exchange jacket
2 Mixing tank
3 Rotating shaft
4 Stirring blade
40 Stirrer blade located in the lower stage
41 Stirring blades located in the lower stage
411 bending part
42 Stirrer blades located at the bottom
421 slit
422 bent part
423 Fin
43 Stirring blades located at the bottom
431 Bending part
432 Fin
44 Stirrer blades located at the bottom
441 Bending part
442 Fin
45 Stirring blades located in the lower stage
46 Stirrer blades located at the bottom
50 Stirring blades located in the upper stage
51 Stirring blade located in the upper stage
511 fins
52 Stirring blades located in the upper stage
53 Stirring blades located in the upper stage
54 Stirring blades located in the upper stage
541 Medium hole
55 Stirring blades located in the middle
56 Stirring blades located in the upper stage
65 Stirring blades located in the upper stage
5a, 5b, 5c, 5d stirring blade
6b, 6c, 6d
7 Upper material inlet
8 Lower material inlet
9 Turbulence forming member
α crossing angle
73 photoconductor
74 Developer carrier
75 sleeve
76 magnet
77 Two-component developer
78 Developer layer regulating member
79 Development Area
80 Developer layer
81 power supply
84 Heating body
85 Alumina substrate
86 Resistance material
87 Thermometer
88 films
89 Driving roller
90 Followed roller
91 Feed axis
92 Winding shaft
93 Unfixed toner image
94 Transfer material
95 Pressure roller
Dsd minimum gap

Claims (18)

  In a magnetic toner for developing an electrostatic image obtained by associating at least a polymerizable monomer in an aqueous medium with resin particles and magnetic powder, the shape coefficient variation coefficient is 16%. Magnetic toner for developing an electrostatic charge image, characterized in that the toner particles have a ratio of toner particles having no corners of 50% by number or more and a number variation coefficient in the number particle size distribution of 27% or less. .   2. The magnetic toner for developing electrostatic images according to claim 1, wherein the proportion of toner particles having a shape factor in the range of 1.2 to 1.6 is 65% by number or more.   The magnetic toner for developing electrostatic images according to claim 1, wherein the number average particle diameter of the toner particles is 3 to 8 μm.   When the particle diameter of the toner particles is D (μm), the natural logarithm lnD is taken on the horizontal axis, and the horizontal axis is divided into a plurality of classes at intervals of 0.23 to the most frequent class in the histogram showing the number-based particle size distribution. The sum (M) of the relative frequency (m1) of the toner particles contained and the relative frequency (m2) of the toner particles contained in the next most frequent class is 70% or more. The magnetic toner for developing an electrostatic image according to claim 1.   The magnetic toner for developing an electrostatic charge image according to any one of claims 1 to 4, wherein the ratio of the major axis to the minor axis of the magnetic powder is at least 0.8.   6. The electrostatic image developing magnetism according to claim 1, wherein the content of at least silicon element in the magnetic powder is 0.1 to 4.0% by mass based on iron element. toner.   The magnetic toner for developing an electrostatic charge image according to any one of claims 1 to 6, wherein the content of FeO in at least the magnetic powder is 20 to 30% by mass.   The magnetic toner for developing an electrostatic charge image according to any one of claims 1 to 7, wherein at least the magnetic powder has a 6 to 20-hedron structure.   The magnetic toner for developing electrostatic images according to claim 1, wherein at least the magnetic powder has a spherical structure. A resin obtained by causing an electrostatic latent image formed on a photoreceptor to face a developer layer formed on a developer conveying member in a non-contact state and polymerizing at least a polymerizable monomer in an aqueous medium. In an image forming method including a developing step in which a magnetic toner for developing an electrostatic charge image obtained by associating particles and magnetic powder in an aqueous medium is ejected, the magnetic toner has a variation coefficient of a shape factor. An image forming method comprising: magnetic toner particles having a toner particle ratio of 16% or less and having no corners of 50% by number or more and a number variation coefficient in a number particle size distribution of 27% or less.   The image forming method according to claim 10, wherein the toner image is visualized by flying magnetic toner having a ratio of toner particles having a shape factor in the range of 1.2 to 1.6 of 65% by number or more.   12. The image forming method according to claim 10, wherein the toner particles are visualized by flying a magnetic toner having a number average particle diameter of 3 to 8 [mu] m.   When the particle diameter of the toner particles is D (μm), the natural logarithm lnD is taken on the horizontal axis, and the horizontal axis is divided into a plurality of classes at intervals of 0.23 to the most frequent class in the histogram showing the number-based particle size distribution. The magnetic toner having a sum (M) of 70% or more of the relative frequency (m1) of the toner particles contained and the relative frequency (m2) of the toner particles contained in the second most frequent class after the mode is fly. The image forming method according to claim 10, wherein the image is visualized.   14. The image forming method according to claim 10, wherein at least a ratio of a major axis to a minor axis of the magnetic powder is 0.8 or more.   The image forming method according to claim 10, wherein the content of at least silicon element in the magnetic powder is 0.1 to 4.0% by mass based on the iron element.   The image forming method according to claim 10, wherein at least the FeO content in the magnetic powder is 20 to 30% by mass.   The image forming method according to claim 10, wherein at least the magnetic powder has a 6-20 icosahedron structure.   The image forming method according to claim 10, wherein at least the magnetic powder has a spherical structure.

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