JP5034549B2 - Method and apparatus for producing toner for electrophotography - Google Patents

Method and apparatus for producing toner for electrophotography Download PDF

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JP5034549B2
JP5034549B2 JP2007042345A JP2007042345A JP5034549B2 JP 5034549 B2 JP5034549 B2 JP 5034549B2 JP 2007042345 A JP2007042345 A JP 2007042345A JP 2007042345 A JP2007042345 A JP 2007042345A JP 5034549 B2 JP5034549 B2 JP 5034549B2
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toner
temperature
softening point
kneader
screw
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JP2008203745A (en
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正博 前田
豊 山崎
忠洋 椿
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Casio Computer Co Ltd
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本発明は、電子写真用トナーの製造方法及び製造装置に係り、特に、安定した軟化点の電子写真用トナーを製造する方法及び製造装置に関する。   The present invention relates to a method and an apparatus for producing an electrophotographic toner, and more particularly, to a method and an apparatus for producing an electrophotographic toner having a stable softening point.

電子写真方式による画像の形成は、一般に静電荷像をトナーにより現像して可視化し、得られたトナー像を用紙に転写することにより行われる。このような画像形成に用いられるトナーには、乾式トナーと湿式トナーがあるが、乾式トナーが主流である。乾式トナーの製造方法としては、粉砕法、重合法等があるが、一般には粉砕法が主流を占めている。   In general, an electrophotographic image is formed by developing and visualizing an electrostatic image with toner and transferring the obtained toner image onto a sheet. The toner used for such image formation includes a dry toner and a wet toner, and the dry toner is the mainstream. As a dry toner manufacturing method, there are a pulverization method, a polymerization method, and the like, but in general, the pulverization method dominates.

粉砕法によるトナーの一般的な製造プロセスは、次の通りである。結着樹脂、着色剤、離型剤、帯電制御剤等の原料を乾式で混合したあと、2軸押出機などで溶融混練し、冷却固化した後に粗粉砕を行い、混練粗砕物を得る。その後ジェットミルなどで微粉砕を行い、適切な粒度分布になるように分級機で粒度調整を行う。さらにシリカなどと一緒に混合機で混合することで表面処理を行い、トナーを得る。   The general manufacturing process of toner by the pulverization method is as follows. Raw materials such as a binder resin, a colorant, a release agent, and a charge control agent are mixed in a dry manner, then melt-kneaded with a twin screw extruder or the like, cooled and solidified, and then coarsely pulverized to obtain a kneaded crushed product. After that, fine pulverization is performed with a jet mill or the like, and the particle size is adjusted with a classifier so as to obtain an appropriate particle size distribution. Furthermore, it is surface-treated by mixing with silica etc. with a mixer to obtain a toner.

このようなトナーの製造プロセスにおいて、混練工程はトナー材料の分散が行われる重要な工程であり、トナー材料が高度に分散されることが求められる。また、混練工程では、トナー材料の分散とともに結着樹脂の分子切断も起こっているため、混練条件はトナーの軟化点に大きな影響を与える。即ち、混練が強すぎると、トナーの溶融粘度が下がり、定着工程でホットオフセット現象という不具合が発生するため、適切な条件を設定する必要がある。トナーの材料分散性の評価としては、TEM(Transmission Electron Microscope:透過型電子顕微鏡)による顔料分散の観察、かぶり評価などがある。   In such a toner manufacturing process, the kneading step is an important step in which the toner material is dispersed, and the toner material is required to be highly dispersed. In the kneading step, the binder resin molecules are also cut along with the dispersion of the toner material. Therefore, the kneading conditions greatly affect the softening point of the toner. That is, if the kneading is too strong, the melt viscosity of the toner decreases, and a problem such as a hot offset phenomenon occurs in the fixing process, so it is necessary to set appropriate conditions. Examples of evaluation of the material dispersibility of the toner include observation of pigment dispersion by a TEM (Transmission Electron Microscope), and evaluation of fogging.

混練条件のうち、混練機のパラメータとしては、2軸押出機の場合、混練機の混練ゾーンの長さ(L)と断面(D)及びその比(L/D)や、スクリューがセグメント方式となっている場合は、そのスクリュー構成が混練強度に大きな影響を与える。製造条件のパラメータとしては、混練機のシリンダー毎のバレル温度設定、スクリュー回転数、原料の供給量が挙げられる。   Among the kneading conditions, as the parameters of the kneader, in the case of a twin screw extruder, the kneading zone length (L), cross section (D) and ratio (L / D), and the screw are segmented In such a case, the screw configuration greatly affects the kneading strength. The parameters of the production conditions include the barrel temperature setting for each cylinder of the kneader, the screw rotation speed, and the raw material supply amount.

しかし、上記混練条件を最適化しても、実際の量産運転において、トナーの軟化点が変動することがある。その原因の一つに使用される結着樹脂の軟化点の変動が挙げられる。即ち、結着樹脂の軟化点が高い場合には、トナーの軟化点が高くなり、結着樹脂の軟化点が低い場合にはトナーの軟化点も低くなる。通常、製品の品質を確保できる範囲で軟化点を規格化しているが、トナーの銘柄、混練条件によっては、その規格を満足しないものが発生する場合があった。   However, even if the kneading conditions are optimized, the softening point of the toner may fluctuate in actual mass production operation. One of the causes is a variation in the softening point of the binder resin used. That is, when the softening point of the binder resin is high, the softening point of the toner is high, and when the softening point of the binder resin is low, the softening point of the toner is also low. Usually, the softening point is standardized within a range where the quality of the product can be ensured, but depending on the brand of the toner and the kneading conditions, a toner that does not satisfy the standard may be generated.

トナーの軟化点が高すぎる場合、光沢度の低下やOHPシートに印字した場合の透明性が悪化し、オーバーヘッドプロジェクターにより良好な画像を映し出すことが困難となる。また、トナーの軟化点が低すぎる場合には、ホットオフセット現象が発生する。通常、これらのバランスを取り、混練条件やトナーの軟化点規格が設定される。結着樹脂の軟化点が変動する原因としては、原料ロット、製造での振れなどが考えられ、一般的には軟化点で4,5℃程度の規格幅を許容しているのが現状である。   When the softening point of the toner is too high, the glossiness is lowered and the transparency when printed on the OHP sheet is deteriorated, and it becomes difficult to display a good image with an overhead projector. Further, when the softening point of the toner is too low, a hot offset phenomenon occurs. Usually, these are balanced and kneading conditions and toner softening point standards are set. Possible causes of fluctuations in the softening point of the binder resin include raw material lots and fluctuations in manufacturing. In general, the standard range of about 4 to 5 ° C. is allowed at the softening point. .

結着樹脂のロットばらつきによる品質不安定の問題を混練工程で解決する方法として、スクリューの回転のための消費電力を一定範囲内に維持すべく、混練機の設定温度又はスクリューの回転数のうちの少なくとも一方を調整することが提案されている(例えば、特許文献1参照)。   As a method of solving the quality instability problem due to lot fluctuation of the binder resin in the kneading process, in order to maintain the power consumption for screw rotation within a certain range, the set temperature of the kneader or the rotation speed of the screw It has been proposed to adjust at least one of the above (see, for example, Patent Document 1).

具体的には、粘弾性の大きな樹脂の場合、スクリューの回転を行うための消費電力が大きくなるため、バレル温度を上げるか又はスクリュー回転数を上げている。また、粘弾性の小さい樹脂の場合、スクリューの回転を行うための消費電力が小さくなるため、バレル温度を下げるか又はスクリュー回転数を下げる調整を行うこととしている。これにより、例えば、トナー中のカーボンブラックの分散状態を安定化することを試みている。   Specifically, in the case of a resin having a large viscoelasticity, power consumption for rotating the screw increases, so the barrel temperature is increased or the screw rotation speed is increased. Further, in the case of a resin having low viscoelasticity, power consumption for rotating the screw is reduced, and therefore, adjustment is made to lower the barrel temperature or lower the screw rotation speed. Thereby, for example, an attempt is made to stabilize the dispersion state of carbon black in the toner.

しかし、上記提案における混練状態の指標は、スクリュー回転数の消費電力であり、混練物の剪断力及び分散性を安定化させるには好ましいと考えられるが、トナーの軟化点を安定化するには、十分な効果が得られない。
特開2003−107800号公報
However, the index of the kneading state in the above proposal is the power consumption of the screw rotation speed, which is considered preferable for stabilizing the shearing force and dispersibility of the kneaded product, but for stabilizing the softening point of the toner. A sufficient effect cannot be obtained.
JP 2003-107800 A

本発明は、このような事情の下になされ、安定化した軟化点を有する電子写真用トナーの製造方法及び製造装置を提供することを目的とする。   An object of the present invention is to provide a method and an apparatus for producing an electrophotographic toner having a stabilized softening point, which has been made under such circumstances.

上記課題を解決するため、本発明の第1の態様は、結着樹脂及び着色剤を含む原料を混合及び2軸押出混練機を用いて溶融混練する工程、及び混練物を冷却固化した後、粉砕及び分級する工程を具備する電子写真用トナーの製造方法において、前記2軸押出混練機の混練機出口の混練物の温度をモニターし、この混練物の温度に応じて前記2軸押出混練機のスクリュー回転数を制御することにより、前記混練物の温度を所定範囲内に維持することを特徴とする電子写真用トナーの製造方法を提供する。 In order to solve the above-mentioned problems, the first aspect of the present invention includes a step of mixing and melting and kneading a raw material containing a binder resin and a colorant using a biaxial extrusion kneader , and cooling and solidifying the kneaded product. In the method for producing an electrophotographic toner comprising the steps of pulverizing and classifying, the temperature of the kneaded material at the kneader outlet of the biaxial extrusion kneader is monitored, and the biaxial extrusion kneader according to the temperature of the kneaded material An electrophotographic toner manufacturing method is provided, wherein the temperature of the kneaded product is maintained within a predetermined range by controlling the number of rotations of the screw.

このような電子写真用トナーの製造方法において、結着樹脂としてポリエステルを用いることができる In such a method for producing an electrophotographic toner, polyester can be used as a binder resin .

本発明の第2の態様は、結着樹脂及び着色剤を含む原料を混合する手段、原料混合物を溶融混練する2軸押出混練機、及び混練物を冷却固化した後、粉砕及び分級する手段を具備する電子写真用トナーの製造装置において、前記2軸押出混練機は、出口の混練物の温度をモニターする手段、及び混練物の温度に応じて前記2軸押出混練機のスクリュー回転数を制御する手段を備え、前記2軸押出混練機のスクリュー回転数の制御により、前記混練物の温度を所定範囲内に維持することを特徴とする電子写真用トナーの製造装置を提供する。
The second aspect of the present invention includes means for mixing raw materials including a binder resin and a colorant, a twin-screw extrusion kneader for melt-kneading the raw material mixture, and means for pulverizing and classifying the kneaded material after cooling and solidifying. In the electrophotographic toner manufacturing apparatus, the biaxial extrusion kneader is a means for monitoring the temperature of the kneaded material at the outlet, and controls the screw rotation speed of the biaxial extrusion kneader according to the temperature of the kneaded material. There is provided an apparatus for producing an electrophotographic toner, characterized in that the temperature of the kneaded product is maintained within a predetermined range by controlling the screw rotation speed of the biaxial extrusion kneader.

本発明によると、安定化した軟化点を有する電子写真用トナーを得ることができる。   According to the present invention, an electrophotographic toner having a stabilized softening point can be obtained.

以下、本発明の実施の形態について説明する。   Embodiments of the present invention will be described below.

本発明者らは、樹脂の軟化点の変動が原因でトナーの軟化点が変動する問題について種々検討した結果、原料として使用する結着樹脂の軟化点と混練機出口の混練物の温度とに相関があることを見出した。また、スクリュー回転数と混練機出口の混練物温度及びトナー軟化点との関係から、混練工程において、混練機出口の混練物の温度をモニターし、それが所定温度範囲内になるように混練機のスクリュー回転数を適宜調整することで、樹脂の軟化点が変動しても、安定したトナー軟化点を有するトナーが得られることを見出した。本発明は、このような知見の下になされたものである。   As a result of various studies on the problem that the softening point of the toner fluctuates due to the fluctuation of the softening point of the resin, the inventors have found that the softening point of the binder resin used as a raw material and the temperature of the kneaded material at the kneader outlet are determined. We found that there is a correlation. In addition, from the relationship between the screw rotation speed, the kneaded material temperature at the kneader outlet, and the toner softening point, the temperature of the kneaded material at the kneader outlet is monitored in the kneading step so that it is within a predetermined temperature range. It was found that a toner having a stable toner softening point can be obtained even if the softening point of the resin fluctuates by appropriately adjusting the screw rotation speed. The present invention has been made under such knowledge.

即ち、混練機出口に設置された温度計により混練機出口の混練物の温度を常時測定し、それが所定範囲の下限を下回る場合には混練機のスクリュー回転数を増加させ、所定範囲の上限を超える場合には混練機のスクリュー回転数を減少させて、混練機出口の混練物の温度を所定範囲内に保持する。それによって、トナーの軟化点を安定化することができる。   That is, the temperature of the kneaded material at the kneader outlet is constantly measured by a thermometer installed at the kneader outlet, and if it is below the lower limit of the predetermined range, the screw rotation speed of the kneader is increased to increase the upper limit of the predetermined range. In the case of exceeding, the screw rotation speed of the kneader is decreased, and the temperature of the kneaded product at the kneader outlet is kept within a predetermined range. Thereby, the softening point of the toner can be stabilized.

次に、以上のような混練の作用に基づく本発明の一実施形態に係るトナーの製造方法について説明する。   Next, a toner manufacturing method according to an embodiment of the present invention based on the above kneading action will be described.

まず、結着樹脂、着色剤、離型剤、及び帯電制御剤等の材料の計量を行い、計量された材料を混合機により混合する。混合機としては、ヘンシェルミキサー、スーパーミキサー、V型ブレンダー、ナウターミキサー等、任意のものを用いることが出来る。
混合物は、次いで、溶融混練される。溶融混練には、2軸押出し混練機、単軸押出し混練機等を用いることが出来る。
First, materials such as a binder resin, a colorant, a release agent, and a charge control agent are measured, and the measured materials are mixed by a mixer. As a mixing machine, arbitrary things, such as a Henschel mixer, a super mixer, a V-type blender, and a Nauta mixer, can be used.
The mixture is then melt kneaded. For melt kneading, a twin screw extrusion kneader, a single screw extrusion kneader, or the like can be used.

図1は、一例としての二軸押出混練機を示す側面図である。この二軸押出混練機は、原料混合物が供給されるフィーダー1、複数のゾーンに区分されたシリンダー2、及び溶融混練物が排出されるダイ3を具備している。シリンダー2の各ゾーンは、ヒーター(図示せず)により所定の温度に加熱されており、またシリンダー2内には、その軸が平行又は所定の角度となるように配置された二本の円筒状のスクリュー4が配置されている。スクリュー4は、同方向に又は反対方向に回転する。また、ダイ3には、混練物の温度を測定するための温度計5が設置されている。   FIG. 1 is a side view showing a twin-screw extrusion kneader as an example. This twin-screw extrusion kneader includes a feeder 1 to which a raw material mixture is supplied, a cylinder 2 divided into a plurality of zones, and a die 3 from which a melt-kneaded product is discharged. Each zone of the cylinder 2 is heated to a predetermined temperature by a heater (not shown), and in the cylinder 2, two cylindrical shapes are arranged so that their axes are parallel or at a predetermined angle. Screw 4 is arranged. The screw 4 rotates in the same direction or in the opposite direction. The die 3 is provided with a thermometer 5 for measuring the temperature of the kneaded product.

ダイ3における混練物の温度測定方法としては様々な方法があるが、より安定して混練物の温度を測定するために、図1に示すような温度計5、例えば熱電対を設置し、常時監視することが望ましい。   There are various methods for measuring the temperature of the kneaded material in the die 3, but in order to measure the temperature of the kneaded material more stably, a thermometer 5 as shown in FIG. It is desirable to monitor.

フィーダー1から供給された、結着樹脂、着色剤、及び離型材を含むトナー原料混合物は、シリンダー2内に導入され、スクリュー4間の間隙において、加熱されているシリンダー2からの熱により溶融されるとともに、スクリューの回転による圧縮力及びせん断力により混合され、スクリュー4のらせん状の羽根に沿ってダイ3の側に移動し、ダイ3から排出される。   The toner raw material mixture including the binder resin, the colorant, and the release material supplied from the feeder 1 is introduced into the cylinder 2 and melted by the heat from the heated cylinder 2 in the gap between the screws 4. At the same time, they are mixed by the compression force and shearing force due to the rotation of the screw, moved along the spiral blades of the screw 4 to the side of the die 3, and discharged from the die 3.

この際、温度計5により検出された混練物の温度に応じて、スクリュー4の回転数が調整される。このスクリュー4の回転数の調整は、手動で行うこともできるが、図1に示すように、温度計5及びモータ7に接続されたコントローラ6により自動的に行うことも可能である。即ち、温度計5からの温度信号がコントローラ6に入力され、コントローラ6からスクリュー4を駆動するモータ7に、回転数を制御する信号が送られる。例えば、混練機出口の混練物の温度を180℃±10℃に設定し、ダイ3における混練物の温度を温度計5によりモニターし、混練物の温度が低くなるとモータ7の回転数を増加させる信号をコントローラ6からモータ7に送り、混練物の温度が高くなるとモータ7の回転数を減少させる信号をコントローラ6からモータ7に送る。その結果、混練物の温度が180℃±10℃の範囲内に保持されるようにモータ7の回転数、即ちスクリュー4の回転数が制御される。   At this time, the rotational speed of the screw 4 is adjusted according to the temperature of the kneaded material detected by the thermometer 5. The adjustment of the rotational speed of the screw 4 can be performed manually, but can also be automatically performed by a controller 6 connected to the thermometer 5 and the motor 7 as shown in FIG. That is, a temperature signal from the thermometer 5 is input to the controller 6, and a signal for controlling the rotational speed is sent from the controller 6 to the motor 7 that drives the screw 4. For example, the temperature of the kneaded material at the kneader outlet is set to 180 ° C. ± 10 ° C., the temperature of the kneaded material in the die 3 is monitored by the thermometer 5, and the number of revolutions of the motor 7 is increased when the temperature of the kneaded material decreases. A signal is sent from the controller 6 to the motor 7, and when the temperature of the kneaded material becomes high, a signal for reducing the rotation speed of the motor 7 is sent from the controller 6 to the motor 7. As a result, the rotation speed of the motor 7, that is, the rotation speed of the screw 4 is controlled so that the temperature of the kneaded material is maintained within the range of 180 ° C. ± 10 ° C.

ダイ3から排出された溶融混練物は、通常、トナーの製造に用いられる方法に従って、冷却され、粉砕され、所定の粒度に分級されて、トナー粒子母体が得られる。冷却手段、粉砕手段及び分級手段は、特に限定されず、通常トナーの製造に用いられるものを採用することが出来る。例えば、冷却には、圧延や空気流の吹き付けによる冷却手段を用いることができ、粉砕には、衝突板式粉砕機等の気流粉砕機を用いることができ、分級には、様々な気流分級機を用いることができる。   The melt-kneaded product discharged from the die 3 is usually cooled, pulverized, and classified to a predetermined particle size according to a method used for toner production to obtain a toner particle matrix. The cooling means, the pulverizing means, and the classification means are not particularly limited, and those usually used for toner production can be employed. For example, a cooling means by rolling or blowing an air flow can be used for cooling, and an airflow pulverizer such as a collision plate pulverizer can be used for pulverization, and various airflow classifiers can be used for classification. Can be used.

このようにして得たトナー粒子母体に、シリカ等の外添剤を加え、混合・攪拌することにより、電子写真用トナーが得られる。   An electrophotographic toner can be obtained by adding an external additive such as silica to the toner particle matrix thus obtained, followed by mixing and stirring.

以上説明したトナーの製造方法によると、混練機出口の混練物の温度が所定範囲に制御されているため、安定した軟化点のトナーを得ることができる。   According to the toner manufacturing method described above, since the temperature of the kneaded material at the kneader outlet is controlled within a predetermined range, a toner having a stable softening point can be obtained.

以下、本発明の実施例と比較例を示し、本発明をより具体的に説明する。   Examples of the present invention and comparative examples are shown below to describe the present invention more specifically.

なお、実施例及び比較例において、結着樹脂として、ロットによって軟化点の異なる以下の樹脂を用いた。   In Examples and Comparative Examples, the following resins having different softening points depending on lots were used as binder resins.

ポリエステル樹脂A:軟化点134℃、軟化点の低いロット
ポリエステル樹脂B:軟化点140℃、軟化点の高いロット
ポリエステル樹脂C:軟化点137℃、軟化点が平均的なロット
実施例1
結着樹脂としてポリエステル樹脂A(軟化点134℃)92質量部、着色剤としてC.Iピグメントレッド57:1を4質量部、荷電制御剤として「LR−147」(日本カーリット(株)製:有機ホウ素化合物)を1質量部、離型剤として「NP056」(三井化学(株)製:ポリプロピレンワックス)3質量部をヘンシェルミキサー(三井鉱山(株)製)を用いて混合した。
Polyester resin A: Lot with softening point 134 ° C., low softening point Polyester resin B: Lot with softening point 140 ° C., high softening point Polyester resin C: Lot with softening point 137 ° C., average softening point Example 1
92 parts by mass of polyester resin A (softening point 134 ° C.) as a binder resin and C.I. 4 parts by weight of I Pigment Red 57: 1, 1 part by weight of “LR-147” (manufactured by Nippon Carlit Co., Ltd .: organoboron compound) as a charge control agent, and “NP056” (Mitsui Chemicals, Inc.) as a release agent 3 parts by mass of polypropylene wax) were mixed using a Henschel mixer (Mitsui Mining Co., Ltd.).

混合粉体を2軸混練機(スクリュー径43mm、L/D=34)により溶融混練し、延伸し、冷却し、ロートプレックス(ホソカワミクロン(株)製、2mmスクリーン)で粗砕した後、衝突式粉砕機・風力分級機にて、トナー平均粒径が9.0μmになるように粉砕分級を行い、微粒子を得た。   The mixed powder is melt-kneaded with a twin-screw kneader (screw diameter: 43 mm, L / D = 34), stretched, cooled, and coarsely crushed with a Rotoplex (manufactured by Hosokawa Micron Corporation, 2 mm screen). Using a pulverizer / air classifier, pulverization classification was performed so that the average particle diameter of the toner was 9.0 μm, and fine particles were obtained.

得られた微粒子100質量部に、外添剤として「R972」(日本アエロジル(株)製:疎水性シリカ)を2質量部添加し、ヘンシェルミキサーで混合してトナーを得た。   To 100 parts by mass of the obtained fine particles, 2 parts by mass of “R972” (manufactured by Nippon Aerosil Co., Ltd .: hydrophobic silica) was added as an external additive and mixed with a Henschel mixer to obtain a toner.

このとき、混練条件としては、供給量30kg/hで行い、混練機を約1時間運転した。混練機出口の混練物の温度をモニターし、180±10℃の範囲となるように混練機のスクリュー回転数を適時可変させた。そのときのスクリュー回転数の可変範囲は、250〜300rpmであった。得られたトナーの軟化点は125℃であった。   At this time, the kneading conditions were performed at a supply rate of 30 kg / h, and the kneader was operated for about 1 hour. The temperature of the kneaded product at the kneader outlet was monitored, and the screw rotation speed of the kneader was varied as appropriate so that the temperature was in the range of 180 ± 10 ° C. The variable range of the screw rotation speed at that time was 250 to 300 rpm. The obtained toner had a softening point of 125 ° C.

実施例2
結着樹脂としてポリエステル樹脂Aの代わりに、ポリエステル樹脂B(軟化点140℃)を使用した以外は実施例1と同様にしてトナーを製造した。
Example 2
A toner was produced in the same manner as in Example 1 except that polyester resin B (softening point 140 ° C.) was used instead of polyester resin A as the binder resin.

混練工程において、混練機出口の混練物の温度をモニターし、180±10℃の範囲となるように混練機のスクリュー回転数を適時可変させた。そのときのスクリュー回転数は、350〜400rpmであった。得られたトナーの軟化点は125℃であった。   In the kneading process, the temperature of the kneaded product at the kneader exit was monitored, and the screw rotation speed of the kneader was varied as appropriate so that it was in the range of 180 ± 10 ° C. The screw rotation speed at that time was 350-400 rpm. The obtained toner had a softening point of 125 ° C.

実施例3
結着樹脂としてポリエステル樹脂Aの代わりに、ポリエステル樹脂C(軟化点137℃)を使用した以外は実施例1と同様にしてトナーを製造した。
Example 3
A toner was produced in the same manner as in Example 1 except that polyester resin C (softening point 137 ° C.) was used instead of polyester resin A as the binder resin.

混練工程において、混練機出口の混練物の温度をモニターし、180±10℃の範囲となるように混練機のスクリュー回転数を適時可変させた。そのときのスクリュー回転数は、325rpmであった。得られたトナーの軟化点は125℃であった。   In the kneading process, the temperature of the kneaded product at the kneader exit was monitored, and the screw rotation speed of the kneader was varied as appropriate so that it was in the range of 180 ± 10 ° C. The screw rotation speed at that time was 325 rpm. The obtained toner had a softening point of 125 ° C.

比較例1
混練工程において混練機のスクリュー回転数を325rpmに固定した以外は実施例1と同様にしてトナーを得た。このときの混練機出口の混練物の温度は195℃であった。得られたトナーの軟化点は122℃であった。
Comparative Example 1
A toner was obtained in the same manner as in Example 1 except that the screw rotation speed of the kneader was fixed at 325 rpm in the kneading step. The temperature of the kneaded material at the kneader outlet at this time was 195 ° C. The softening point of the obtained toner was 122 ° C.

比較例2
混練工程において混練機のスクリュー回転数を325rpmと固定した以外は実施例2と同様にしてトナーを得た。このときの混練機出口の混練物の温度は160℃であった。得られたトナーの軟化点は128℃であった。
Comparative Example 2
A toner was obtained in the same manner as in Example 2 except that the screw rotation speed of the kneader was fixed at 325 rpm in the kneading step. The temperature of the kneaded material at the kneader outlet at this time was 160 ° C. The softening point of the obtained toner was 128 ° C.

比較例3
混練工程でスクリュー回転数を250rpmと固定した以外は実施例3と同様にしてトナーを得た。このときの混練機出口の混練物の温度は150℃であった。得られたトナーの軟化点は129℃であった。
Comparative Example 3
A toner was obtained in the same manner as in Example 3 except that the screw rotation speed was fixed at 250 rpm in the kneading step. The temperature of the kneaded material at the kneader outlet at this time was 150 ° C. The resulting toner had a softening point of 129 ° C.

比較例4
混練工程でスクリュー回転数を400rpmと固定した以外は実施例3と同様にしてトナーを得た。このときの混練機出口の混練物の温度は195℃であった。得られたトナーの軟化点は120℃であった。
Comparative Example 4
A toner was obtained in the same manner as in Example 3 except that the screw rotation speed was fixed at 400 rpm in the kneading step. The temperature of the kneaded material at the kneader outlet at this time was 195 ° C. The resulting toner had a softening point of 120 ° C.

混練条件
2軸押出機(スクリュー径43mm、L/D=34)を使用し、混練温度は、スクリュー長さ方向にC1からC7までの7つのゾーンとアダプタとダイにおいて、C1が50℃、C2からC4が100℃、C5からC7が130℃、アダプタ及びダイを150℃に設定した。
Kneading conditions A twin-screw extruder (screw diameter 43 mm, L / D = 34) was used, and the kneading temperature was 7 zones C1 to C7 in the screw length direction, adapter and die, C1 was 50 ° C, C2 To C4 were set to 100 ° C, C5 to C7 were set to 130 ° C, and the adapter and the die were set to 150 ° C.

以下の特性について評価する。   The following characteristics are evaluated.

試験1−OHP透過度
非磁性一成分現像装置「カシオページプレストN−5」(カシオ計算機(株)製:カラープリンタ毎分29枚機(A4横))にトナーを実装し、通常環境(25℃、50%RH)において、OHP用紙(専用OHPシートN−OHPS)にベタ印字画像を印字した後、得られた画像をオーバーヘッドプロジェクターにてスクリーンに投光し、発色性、透明性を評価した。
Test 1-OHP Permeability Non-magnetic one-component developing device “Casio Page Presto N-5” (manufactured by Casio Computer Co., Ltd .: color printer, 29 sheets per minute (A4 side)) in normal environment (25 After printing a solid print image on OHP paper (dedicated OHP sheet N-OHPS) at 50 ° C. and 50% RH), the obtained image was projected onto a screen with an overhead projector to evaluate color development and transparency. .

試験2−定着特性
試験1で用いたのと同様の現像装置の定着部分の温度を可変できるように改造し、定着試験器とする。前記定着試験器にて定着温度130〜200℃の範囲で10℃毎に温度を可変し、印字を行い、定着性を評価した。ここでいう定着温度は2本ある定着ロールの上の方の設定温度であり、下の定着ロールは設定温度を上ロール−20℃とした。画像パターンはベタ印字とし、用紙はXEROX P紙A4サイズ(64g/m2 )で行った。
Test 2-Fixing characteristics The fixing device is modified so that the temperature of the fixing portion of the developing device similar to that used in Test 1 can be varied. With the fixing tester, the temperature was varied every 10 ° C. within the fixing temperature range of 130 to 200 ° C., printing was performed, and the fixing property was evaluated. The fixing temperature here is the upper set temperature of the two fixing rolls, and the lower fixing roll is set to the upper roll of −20 ° C. The image pattern was solid printing, and the paper was XEROX P paper A4 size (64 g / m 2 ).

トナーの軟化点の測定
装置:フローテスター(島津製作所製、CFT−500D)
試料:1g
昇温速度:6℃/分
荷重:樹脂の軟化点を測定する場合は30kg、トナーの軟化点を測定する場合は20kgで行った。
Measurement of softening point of toner Device: Flow tester (manufactured by Shimadzu Corporation, CFT-500D)
Sample: 1g
Temperature increase rate: 6 ° C./min Load: 30 kg when measuring the softening point of the resin, 20 kg when measuring the softening point of the toner.

ノズル:直径1mm、長さ1mm
1/2法:試料の半分が流出した温度を軟化点とした。
Nozzle: 1mm diameter, 1mm length
1/2 method: The temperature at which half of the sample flowed out was taken as the softening point.

サンプル及び測定環境は極端な温湿度にならないよう十分配慮した。   The sample and measurement environment were carefully considered to avoid extreme temperature and humidity.

トナーの粒径の測定
装置:マルチサイザーII(コールター(株)製)
試料:ビーカーに試料少量と精製水、界面活性剤を入れ、超音波洗浄器にて分散した。
Toner particle size measurement device: Multisizer II (Coulter Co., Ltd.)
Sample: A small amount of sample, purified water, and a surfactant were placed in a beaker and dispersed with an ultrasonic cleaner.

測定:アパーチャーは100μmで行い、カウントは50,000個で行い、体積平均粒径を得た。   Measurement: The aperture was 100 μm, the count was 50,000, and the volume average particle size was obtained.

実施例1〜3、比較例1〜4の各トナーについて、上記試験及び測定を行った。その結果を下記表1に示す。

Figure 0005034549
The above tests and measurements were performed on the toners of Examples 1 to 3 and Comparative Examples 1 to 4. The results are shown in Table 1 below.
Figure 0005034549

上記表1から、次のことがわかる。即ち、混練物の温度が180±10℃になるようにスクリュー回転数を調整した実施例1〜3により得たトナーは、用いた結着樹脂の軟化点が変わっても、OHP透過度及び定着特性のいずれもが良好であった。   From Table 1 above, the following can be understood. That is, the toners obtained in Examples 1 to 3 in which the screw rotation speed was adjusted so that the temperature of the kneaded product was 180 ± 10 ° C., even if the softening point of the binder resin used changed, All of the characteristics were good.

これに対し、混練物の温度にかかわらずスクリュー回転数を一定のままとした比較例1及び2により得たトナーは、用いた結着樹脂の軟化点により軟化点が大きく変化し、OHP透過度及び定着特性のいずれも不良であった。また、比較例3及び4により得たトナーは、混練回転数と混練物温度、トナー軟化点の関係を見出すために試作したトナーであり、低いスクリュー回転数の場合に、混練物の温度は大きく低下し、トナーの軟化点は非常に高くなり、高いスクリュー回転数の場合に、混練物の温度は大きく上昇し、トナーの軟化点は非常に低くなった。また、OHP透過度及び定着特性のいずれもが不良であった。  On the other hand, the toners obtained in Comparative Examples 1 and 2 in which the screw rotation number remained constant regardless of the temperature of the kneaded product, the softening point changed greatly depending on the softening point of the binder resin used, and the OHP permeability Both the fixing characteristics and the fixing characteristics were poor. Further, the toners obtained in Comparative Examples 3 and 4 are toners experimentally produced in order to find out the relationship between the kneading rotational speed, the kneaded product temperature, and the toner softening point. When the screw rotational speed is low, the temperature of the kneaded product is large. As a result, the softening point of the toner became very high, and when the screw rotation speed was high, the temperature of the kneaded material increased greatly, and the softening point of the toner became very low. Further, both the OHP transmittance and the fixing characteristics were poor.

次に、本発明者らは、スクリュー回転数と混練物の(混練機出口)温度及びトナー軟化点との関係、結着樹脂の軟化点と混練物の(混練機出口)温度及びトナー軟化点との関係、及び結着樹脂の軟化点と混練物の(混練機出口)温度及びトナー軟化点との関係を求める実験を行い、図2〜4に示すような結果を得た。   Next, the present inventors have investigated the relationship between the screw rotation speed, the kneaded product (kneader exit) temperature and the toner softening point, the binder resin softening point, the kneaded product (kneader exit) temperature, and the toner softening point. And the relationship between the softening point of the binder resin and the temperature of the kneaded product (kneader outlet) and the toner softening point were obtained, and the results shown in FIGS.

1.137℃の軟化点の結着樹脂を用い、スクリュー回転数を変化させた場合、図2に示すように、スクリュー回転数の上昇とともに混練物の(混練機出口)温度が上昇し、トナーの軟化点が下降する。これは、スクリュー回転数を上げると、樹脂の分子切断が激しくなり、混練物が発熱したためと考えられる。   When a binder resin having a softening point of 1.137 ° C. is used and the screw rotation speed is changed, as shown in FIG. 2, the temperature of the kneaded product (kneader outlet) increases as the screw rotation speed increases. The softening point decreases. This is presumably because when the screw rotation speed is increased, the molecular cutting of the resin becomes severe and the kneaded product generates heat.

2.スクリュー回転数を325rpmと一定にし、使用する結着樹脂の軟化点を変化させた場合、図3に示すように、結着樹脂の軟化点の上昇とともに混練物の(混練機出口)温度は下降し、トナーの軟化点は上昇する。これは、結着樹脂の軟化点が高い時は、混練物温度が低いことから、樹脂の分子切断が少なく、結果として、トナー軟化点が上昇したものと考えられる。   2. When the screw rotation speed is kept constant at 325 rpm and the softening point of the binder resin used is changed, as shown in FIG. 3, the temperature of the kneaded product (kneader outlet) decreases as the softening point of the binder resin increases. In addition, the softening point of the toner increases. This is considered that when the softening point of the binder resin is high, the temperature of the kneaded product is low, so that the resin has little molecular cutting, and as a result, the toner softening point is increased.

3.混練物の(混練機出口)温度を180℃に一定になるようにスクリュー回転数を変化させた場合、図4に示すように、結着樹脂の軟化点が変化しても、トナーの軟化点は一定のままである。   3. When the screw rotation speed is changed so that the temperature of the kneaded product (kneader outlet) becomes constant at 180 ° C., as shown in FIG. 4, even if the softening point of the binder resin changes, the softening point of the toner Remains constant.

以上のように、図2〜4に示す結果から、混練物の(混練機出口)温度を180℃に一定になるようにスクリュー回転数を変化させることにより、結着樹脂の軟化点が変化しても、トナーの軟化点は安定化し得ることがわかる。   As described above, from the results shown in FIGS. 2 to 4, the softening point of the binder resin is changed by changing the screw rotation speed so that the temperature of the kneaded product (kneader outlet) becomes constant at 180 ° C. However, it can be seen that the softening point of the toner can be stabilized.

本発明の一実施形態に使用される二軸押出混練機を示す側面図である。It is a side view which shows the twin-screw extrusion kneader used for one Embodiment of this invention. スクリュー回転数と混練物の(混練機出口)温度及びトナー軟化点との関係を示す特性図である。FIG. 6 is a characteristic diagram showing the relationship between the screw rotation speed, the temperature of the kneaded product (kneader exit), and the toner softening point. 結着樹脂の軟化点と混練物の(混練機出口)温度及びトナー軟化点との関係を示す特性図である。FIG. 6 is a characteristic diagram showing the relationship between the softening point of a binder resin, the temperature of the kneaded product (kneader exit), and the toner softening point. 結着樹脂の軟化点と混練物の(混練機出口)温度及びトナー軟化点との関係を示す特性図である。FIG. 6 is a characteristic diagram showing the relationship between the softening point of a binder resin, the temperature of the kneaded product (kneader exit), and the toner softening point.

符号の説明Explanation of symbols

1…フィーダー、2…シリンダー、3…ダイ、4…スクリュー、5…温度計、6…コントローラ、7…モータ。   DESCRIPTION OF SYMBOLS 1 ... Feeder, 2 ... Cylinder, 3 ... Die, 4 ... Screw, 5 ... Thermometer, 6 ... Controller, 7 ... Motor.

Claims (3)

結着樹脂及び着色剤を含む原料を混合及び2軸押出混練機を用いて溶融混練する工程、及び混練物を冷却固化した後、粉砕及び分級する工程を具備する電子写真用トナーの製造方法において、前記2軸押出混練機の混練機出口の混練物の温度をモニターし、この混練物の温度に応じて前記2軸押出混練機のスクリュー回転数を制御することにより、前記混練物の温度を所定範囲内に維持することを特徴とする電子写真用トナーの製造方法。 In a method for producing an electrophotographic toner comprising a step of mixing and kneading a raw material containing a binder resin and a colorant using a twin-screw extrusion kneader , and a step of cooling and solidifying the kneaded material followed by pulverization and classification by monitoring the temperature of the kneaded material in the kneading machine outlet of the two-axis extrusion kneader, and controls the screw rotation speed of the two-axis extrusion kneader according to the temperature of the kneaded product, the temperature of the kneaded product A method for producing an electrophotographic toner, wherein the toner is maintained within a predetermined range. 前記結着樹脂がポリエステルであることを特徴とする請求項1に記載の電子写真用トナーの製造方法。   The method for producing an electrophotographic toner according to claim 1, wherein the binder resin is polyester. 結着樹脂及び着色剤を含む原料を混合する手段、原料混合物を溶融混練する2軸押出混練機、及び混練物を冷却固化した後、粉砕及び分級する手段を具備する電子写真用トナーの製造装置において、前記2軸押出混練機は、出口の混練物の温度をモニターする手段、及び混練物の温度に応じて前記2軸押出混練機のスクリュー回転数を制御する手段を備え、前記2軸押出混練機のスクリュー回転数の制御により、前記混練物の温度を所定範囲内に維持することを特徴とする電子写真用トナーの製造装置。 Electrophotographic toner production apparatus comprising means for mixing raw materials containing a binder resin and a colorant, a twin-screw extrusion kneader for melting and kneading the raw material mixture, and means for cooling and solidifying the kneaded material, followed by pulverization and classification in the biaxial extrusion kneader, the means for monitoring the temperature of the kneaded material at the outlet, and in accordance with the temperature of the kneaded product comprising means for controlling the screw rotation speed of the two-axis extrusion kneader, the two-axis extrusion An apparatus for producing an electrophotographic toner, characterized in that the temperature of the kneaded product is maintained within a predetermined range by controlling the number of screw revolutions of the kneader.
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