JP2004334041A - Toner, masterbatch for toner and method for evaluating masterbatch for toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for evaluating whether a masterbatch for a toner is good or not, and to provide a good masterbatch for a toner obtained by the evaluation method and a toner. <P>SOLUTION: In the method for evaluating a masterbatch for a toner consisting essentially of a binder resin and a colorant, whether relation satisfying -6≤logRm-logRr is established or not between the volume resistivity Rr (Ωcm) of the binder resin and the volume resistivity Rm (Ωcm) of the masterbatch is ascertained. The masterbatch for a toner establishes relation satisfying -6≤logRm-logRr according to the evaluation method. The toner comprises the masterbatch for a toner and has a volume average particle diameter of ≤7 μm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

−トナーの製造例−
【００６０】
【実施例９】
結着樹脂（三洋化学社製 ポリエステル樹脂） ８０部
マスターバッチ１ ２０部
帯電制御剤 保土谷化学社製 スピロンブラックＴＲＨ ２部
ポリプロピレンワックス 三井化学社製ＮＰ５０５ ４部
上記材料をスーパーミキサーで均一混合したあと、内温１５０℃の二軸押出機で混練、冷却物をジェットミルで微粉砕し、ディスパージョンセパレータで分級し平均粒径６．５μｍの着色剤含有粒子を得た。このこの着色剤含有粒子に市販シリカ（一次平均粒子径が０．１μｍ 、疎水化度 ５０％）を１部混合分散し、トナー１を得た。
【００６１】
【実施例１０】
マスターバッチ２を用いること以外、実施例９と同様にしてトナー２を得た。
【００６２】
【実施例１１】
マスターバッチ３を用いること以外、実施例９と同様にしてトナー３を得た。
【００６３】
【実施例１２】
マスターバッチ４を用いること以外、実施例９と同様にしてトナー４を得た。
【００６４】
【実施例１３】
結着樹脂（三井化学社製 スチレン−アクリル系樹脂） ８０部
マスターバッチ７ ２０部
帯電制御剤 保土谷化学社製 スピロンブラックＴＲＨ ２部
ポリプロピレンワックス 三井化学社製ＮＰ５０５ ４部
上記材料をスーパーミキサーで均一混合したあと、内温１５０℃の二軸押出機で混練、冷却物をジェットミルで微粉砕し、ディスパージョンセパレータで分級し平均粒径６．５μｍの着色剤含有粒子を得た。このこの着色剤含有粒子に市販シリカ（一次平均粒子径が０．１μｍ 、疎水化度 ５０％）を１部混合分散し、トナー５を得た。
【００６５】
【実施例１４】
マスターバッチ８ を用いること以外、実施例１３と同様にしてトナー６を得た。
【００６６】
【比較例２】
マスターバッチ５を用いること以外、実施例９と同様にしてトナー７を得た。
【００６７】
【比較例３】
マスターバッチ６を用いること以外、実施例９と同様にしてトナー８を得た。
【００６８】
【比較例４】
マスターバッチ９を用いること以外、実施例１３と同様にしてトナー９を得た。
【００６９】
【比較例５】
平均粒径を７．５μｍ にすること以外は、実施例９と同様にしてトナー１０を得た。
−トナーの評価−
（１） 黒色度
トナー１〜１０にフェライトキャリア（パウダーテック（株）製Ｆ−１５０）を均一混合し、市販複写機（シャープ（株）ＡＲ−５０５）に、得られた現像剤を実装し、下記に示す評価を行った。
【００７０】
複写機ＡＲ−５０５（シャープ社製）に現像剤を実装し、現像剤中のトナー濃度を変化させながら、全面黒の画像をとり、その画像濃度を光学反射密度を反射濃度計 ＲＤ−９１５（マクベス社製）で測定し、画像濃度１．４０を越えるトナー濃度を求め、以下の基準で判定した。
【００７１】
◎ ： ３．５％未満
○ ： ３．５％以上 ４％未満
△ ： ４％以上 ５％未満
× ： ５％以上
結果を表２に示す。
【００７２】
（２）帯電性
トナー１〜１０の各々４部にフェライトキャリア（パウダーテック（株）製Ｆ−１５０）９６部を均一混合し、複写機ＡＲ−５０５（シャープ社製）に現像剤を実装し、温度２５℃／湿度５０％の環境での帯電量を測定し、その後、温度３５℃／湿度８０％の環境での帯電量を測定した。その変化率
｛（２５℃／５０％での帯電量）−（３５℃／８０％での帯電量）｝ ／ （２５℃／５０％での帯電量）を以下の基準で判定した。
【００７３】
◎ ： ５ ％未満
○ ： ５ ％以上 １０％未満
△ ： １０％以上 ２０％未満
× ： ２０％以上
結果を表２に示す。
【００７４】
【表２】

【００７５】
【発明の効果】
以上述べたように、本発明によると、良好なトナー用マスターバッチであるか否かを評価することができ、少ないトナー量でも高い画像濃度を達成できる良好なトナー用マスターバッチや、それを用いた電子写真用トナーを得ることができる。
【図面の簡単な説明】
【図１】摩擦帯電量測定装置の全体構成の概略を示す斜視図である。
【符号の説明】
１ 摩擦帯電量測定装置[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for evaluating a carbon black masterbatch used for electrophotography and the like, a masterbatch obtained through the evaluation method, and a toner for developing an electrostatic image using the masterbatch.
[0002]
[Prior art]
As the electrophotographic method, various methods are known as described in Patent Document 1. In general, an electric latent image is formed on a photoreceptor by various means using a photoconductive substance. Then, the latent image is developed using toner, and if necessary, the toner image is electrostatically transferred onto a recording material such as paper, and then the toner image is fixed by heating, pressure, solvent vapor, or the like. I have a copy. Also, various methods have been conventionally proposed as a method of developing using toner or a method of fixing a toner image, and a method suitable for each image forming process is adopted. In recent years, more advanced techniques such as high-speed copying, high image quality, and high stability have been required for the above-described electrophotographic method.
[0003]
On the other hand, the toner used in the electrophotographic method is obtained by mixing, melt-kneading raw materials containing a binder resin, a dye / pigment as a colorant, a charge control agent, a wax, and the like, and then pulverizing and classifying. . The important point in this case is to disperse additives such as dyes and pigments and charge control agents in the binder resin to a uniform state. That is, when the dispersion of these additives is poor, the charging characteristics are deteriorated, which causes fluctuations in image characteristics and image deterioration such as fogging and toner scattering.
[0004]
Here, as a typical method for producing the toner, for example, a coloring agent, an anti-offset agent and a charge control agent are contained in a binder resin such as a styrene resin, a styrene- (meth) acrylic resin, a polyester resin or an epoxy resin. Such a method is used in which a raw material having a desired particle size is obtained by dispersing raw materials such as by melting and kneading, pulverizing the kneaded material with a fine pulverizer, and classifying the pulverized material with a classifier. At this time, carbon black is widely used as a colorant for a black toner.
[0005]
However, it has been found that when carbon black is not sufficiently dispersed in the toner thus manufactured, irregular reflection of incident light hardly occurs, and as a result, the toner itself does not look black. As a result, a large amount of toner must be consumed in order to obtain an image having a certain density. Further, carbon black is easily exposed on the surface of the toner, and since the carbon black is generally a conductor, the resistance of the toner may be partially reduced, and the charge amount of the toner varies. As a result, fluctuations in image characteristics, fogging, toner scattering and the like are likely to occur, resulting in poor recording stability.
[0006]
Several methods have been proposed to address the problem of poor dispersion. For example, there is a method in which a so-called masterbatch in which a binder resin contains a dye / pigment having a concentration higher than the dye / pigment concentration in the toner is prepared in advance, and the masterbatch is used as a colorant.
[0007]
Heretofore, this masterbatch has mainly been produced mainly by a method of premixing a binder resin and a dye and then kneading the mixture with a two-roll mill or the like.
[0008]
As another method of manufacturing a master batch, for example, as described in Patent Document 2, a method is described in which raw materials are dissolved and mixed in a solvent, and then the solvent is evaporated to produce a master batch.
[0009]
As a method for producing a toner from these master batches, for example, as shown in Patent Document 3, after the master batch produced by the above method is finely pulverized, the remaining resin is blended, and the mixture is melt-kneaded. Is described.
[0010]
Further, Patent Document 4 describes a method of producing a toner by applying a strong shearing force during the preparation of a masterbatch containing a high concentration of a dye / pigment in a binder resin, while applying a weak shearing force in a dilution kneading step. Have been.
[0011]
[Patent Document 1] U.S. Pat. No. 2,297,691
[Patent Document 2] Japanese Patent Application Laid-Open No. 61-156054
[Patent Document 3] JP-A-62-30259
[Patent Document 4] JP-A-63-205664
[0012]
[Problems to be solved by the invention]
In order to obtain a toner having a high coloring power (a darker toner), the dispersibility of carbon black, which is a coloring pigment, is important, but the blackness of carbon black increases as the primary particle diameter decreases. On the other hand, the cohesion between the particles also increases. That is, producing a toner having a high coloring power and producing a toner having a sufficient dispersibility are to balance the conflicting relationship.
[0013]
Therefore, even in the case of a good toner masterbatch or toner manufacturing method as in the above-described conventional manufacturing method, it is actually determined whether or not a good product is produced by exhibiting the effect of the manufacturing method. Unless it is confirmed every time, it cannot be guaranteed that the product can exhibit sufficient performance.
[0014]
The present invention has been made in view of the above circumstances, and provides a method for evaluating whether or not a toner masterbatch is good, and a good toner masterbatch and toner obtained by this evaluation method. It is aimed at.
[0015]
[Means for Solving the Problems]
The above object is achieved by the present invention described below.
[0016]
A method for evaluating a master batch comprising at least a binder resin and a colorant, wherein a volume resistivity R r (Ω · cm) of the binder resin and a product volume resistance Rm (Ω · cm) of the master batch are: It is to confirm whether or not a relationship that satisfies −6 ≦ logRm−logRr holds.
[0017]
The present inventors have found that by using a carbon black masterbatch satisfying the above relationship at the time of toner production, it becomes possible to disperse carbon black in a state of being dispersed in a toner in a uniform state. Is used, the blackness of the toner itself can be improved, and as a result, a desired image density can be obtained with a smaller amount of adhesion (consumption) than conventional toners. In addition, it has been found that good image characteristics can be stably maintained without toner scattering and image fogging because of good dispersibility.
[0018]
The carbon black masterbatch for toner is basically manufactured by preliminarily mixing a binder resin and a compound mainly composed of highly mixed carbon black, followed by melt-kneading. In the production of this carbon black masterbatch, first, the binder resin used in the production is selected on the basis of a binder resin for a toner, so that there is a considerable limitation in composition. Further, in the above-described manufacturing process, it is necessary to disperse the carbon black in a state where the individual primary particles are aggregated in the binder resin as finely and uniformly as possible while preventing reaggregation. In order to overcome the cohesive force of the dispersed carbon black, it is necessary to take measures such as strengthening the interaction between the binder resin and the carbon black. As such a device, for example, the combination of the pH of carbon black and the acid value of the resin is optimized, or a functional group that is chemically bonded to the functional group present on the surface by the surface treatment of carbon black is used. There is a method of selecting a binder resin having a large amount.
[0019]
Generally, when a conductor such as carbon black is dispersed in an insulator such as a binder resin, the volume resistance value of the obtained dispersion itself may be determined by the degree of dispersion of the conductor in the insulator. Are known. In other words, the better the dispersion of the conductor, the closer the volume resistance of the dispersion to the volume resistance of the binder resin alone. This is because a conductive path is hardly formed in the dispersion by uniformly dispersing the conductor in the binder resin. On the other hand, if the dispersion of the conductor is poor, a conductive path is likely to be formed, and thus the volume resistance of the dispersion decreases.
[0020]
Therefore, the dispersion state of the conductor in the binder resin can be evaluated by measuring the volume resistance value of the dispersion.
[0021]
The masterbatch evaluation method of the present invention checks whether or not the relationship of −6 ≦ logRm−logRr is satisfied between the volume resistance Rr of the binder resin and the volume resistance Rm of the masterbatch. is there.
[0022]
That is, as a measure of dispersibility, when the volume resistance R 1 of the masterbatch satisfies the above relationship with the binder resin Rr, it indicates that the dispersion state of carbon black in the masterbatch is good, When an image is formed using a toner manufactured from such a carbon black master batch, a darker toner can be obtained, and as a result, the amount of toner required to obtain a certain image density is small. Help me.
[0023]
As described above, in the carbon black masterbatch for toner of the present invention, carbon black is dispersed in the masterbatch in a small and uniform particle size. The toner for developing an electrostatic charge image of the present invention, which is excellent in image quality, can be obtained. Hereinafter, this will be described.
[0024]
As the binder resin, a styrene-acrylic copolymer, an acrylic polymer, a polyester resin and the like are known materials.
[0025]
As the acrylic resin, what is called an acrylic resin is used. Usually, methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, methyl methacrylate, ethyl methacrylate, and n-butyl methacrylate are used. And acrylates such as 2-ethylhexyl methacrylate or methacrylate homopolymers. As the styrene-acrylic resin, a copolymer of styrene and a monomer constituting the acrylic resin is used. Among these resins, n-butyl methacrylate resin, methyl methacrylate resin, and styrene-methyl methacrylate copolymer are preferable, and n-butyl methacrylate resin is particularly preferable.
[0026]
The polyester resin can be synthesized from a polyhydric alcohol and a polyhydric carboxylic acid as exemplified below, but is not limited thereto.
[0027]
Examples of the polyhydric alcohol include 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, triethylene glycol, 1,5 -Pentanediol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, bisphenol A, hydrogenated bisphenol A, and polyoxyethylenated bisphenol A and poly And dihydric alcohols such as bisphenol A alkylene oxide adducts such as oxypropylene-modified bisphenol A (bisphenol A propylene oxide).
[0028]
Further, a polyhydric alcohol having a valency of 3 or more can be used in order to make the polymer non-linear so as not to generate a tetrahydrofuran insoluble component. Glycerin, sorbitol, 1,2,3,6-hexanetetraol, 1,4-sorbitan, pentaerythritol, 1,2,4-butanetriol, 1,2,5- Examples include pentanetriol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, and 1,3,5-trihydroxymethylbenzene.
[0029]
On the other hand, polycarboxylic acids include, for example, maleic acid, fumaric acid, mesaconic acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, terephthalic acid, isophthalic acid, cyclohexanedicarboxylic acid, malonic acid, succinic acid, adipic acid And dibasic carboxylic acids, such as sebacic acid, glutaric acid, and alkyl succinic acids (eg, n-octyl succinic acid and n-dodecenyl succinic acid), trimellitic acid, and anhydrides and alkyl esters thereof. Examples of the combination of the above-mentioned polyhydric alcohol and polycarboxylic acid include a combination of bisphenol A propylene oxide with terephthalic acid, fumaric acid, trimellitic anhydride or a mixture thereof.
[0030]
Commercially available carbon blacks that can be used in the present invention include, for example, Regal 400R, 500R, 660R manufactured by Cabot Corporation of the United States; Raven H20, Raven 16, Raven 14, and Raven 430 manufactured by Colombian Carbon Japan Co., Ltd. Raven 450, Raven 500; Printex 200, Printex A, Special Black 4, Printex G, manufactured by Degussa West Germany; and the like, but not limited thereto. These carbon blacks can be used alone or in combination of two or more in various compositions.
[0031]
If the primary particle size of the carbon black is smaller than 10 nm, the specific surface area of the carbon black is large, and the cohesive strength is increased. Therefore, it is very difficult to disperse the carbon black in the binder resin. On the other hand, if the primary particle size of the carbon black is larger than 100 nm, the blackness of the carbon black itself becomes low. Even if a master batch is prepared using such a carbon black and a toner is prepared, a sufficient image density can be obtained. You can't get it. From the above, the primary particle size of carbon black is preferably from 10 nm to 100 nm, and more preferably from 10 nm to 60 nm.
[0032]
In the present invention, such carbon black is blended in such an amount that the carbon black concentration in the masterbatch is 5 to 60% by weight. However, when the carbon black concentration is lower than 30% by weight, It is difficult to uniformly disperse carbon black in a binder resin. In such a case, a master batch having a concentration of 30% or more is once prepared and diluted to obtain a master batch having a desired concentration. If the concentration of carbon black in the masterbatch exceeds 60%, the viscosity of the masterbatch itself increases, the uniform diffusibility into the binder resin decreases, and the dispersibility decreases. Therefore, it is not preferable that the concentration of carbon black in the master batch is too high, and it is preferable that the concentration of carbon black in the master batch be 30 to 60% by weight.
[0033]
The masterbatch of the present invention can be obtained by various mixing methods. In general, for example, after mixing the binder resin powder or pellets of the master batch and the coloring pigment carbon black with a tumbler or a super mixer, the mixture is heated and melt-kneaded by a kneading machine such as an extruder or a Banbury mixer. It is a method of pelletizing or coarsening.
[0034]
As another method, there is also a method of mixing at the time of synthesizing the polycarbonate oligomer. For example, a master batch can be prepared by adding and mixing carbon black to a polycarbonate oligomer in a solution state after the reaction, removing the solvent, and kneading with a kneading machine such as an extruder or a Banbury mixer.
[0035]
In the masterbatch of the present invention, if necessary, various known additives, reinforcing agents, fillers, stabilizers, ultraviolet absorbers, antistatic agents, lubricants, mold release added to the resin composition It is also possible to incorporate agents, dyes, pigments, other flame retardants, and elastomers for improving impact resistance. Of these, the addition of a lubricant, a release agent or an elastomer for improving impact resistance is particularly suitable for lowering the viscosity of the masterbatch.
[0036]
The blending of these additives varies depending on the type and amount of the additives, but may be preliminarily mixed with carbon black or a polycarbonate oligomer, or when carbon black is melt-kneaded with a base resin polycarbonate oligomer or after melt-kneading. You can also. It is preferable to add a lubricant, a release agent, and the like when melt-kneading the carbon black with the polycarbonate oligomer of the base resin or after melt-kneading.
[0037]
Further, when various additives are blended in the master batch as described above, the amount of the additives is considerably smaller than the amount of carbon black. Therefore, it can be considered that even if a conductive additive is blended similarly to carbon black, it does not affect the volume resistivity of the master batch. If a specific additive that affects the volume resistance of the master batch is mixed, the measured volume resistance of the master batch should be corrected according to the type and amount of the additive. You may.
[0038]
The carbon black masterbatch obtained as described above is pulverized to an appropriate particle size and then selected so as to satisfy various characteristics such as developing property, transfer property and fixing property required for the toner. After being pre-mixed with a binder resin, a charge control agent, and other additives, steps such as melt-kneading, cooling, coarse / fine pulverization, classification, and external addition are performed in accordance with a conventional toner production method. Through toner.
[0039]
The toner of the present invention may optionally contain a release agent. Examples of the release agent include any release agents known per se, for example, aliphatic compounds such as aliphatic resins, aliphatic metal salts, higher fatty acids, fatty acid esters and partially saponified products thereof. . Specifically, for example, low-molecular-weight polypropylene, high-molecular-weight polyethylene, paraffin wax, low-molecular-weight olefin polymer composed of olefin alone having 4 or more carbon atoms, silicone oil, various waxes, and the like can be used.
[0040]
The toner of the present invention may be subjected to an external addition treatment for further improving the fluidity. The external additive is not particularly limited as long as it can be added to the toner particles to improve the fluidity after the addition. For example, a silica fine powder, a titanium oxide derivative, an alumina derivative, a material obtained by hydrophobizing the surface thereof, or the like can be used alone or in combination of two or more.
[0041]
A charge control agent can be added to the toner of the present invention as needed. For example, oil-soluble dyes such as nigrosine dyes, oil blacks and spiron blacks; metals which are metal salts such as manganese, iron, cobalt, nickel, lead, zinc, cerium and calcium of naphthenic acid, octylic acid, fatty acids and resin acids Soaps; metal-containing azo dyes, pyrimidine compounds; metal compounds of salicylic acid or its derivatives, such as chromium, aluminum and iron. Usually, these additives are used in the range of 0.1 to 10 parts by weight based on the developer.
[0042]
As the toner particles, particles having an average particle size of 7 μm or less are used. The smaller the average particle diameter of the toner, the more the toner particles can fill the paper (media) with no gap, and the more the paper (media) cannot be seen through, so that the concealment property is improved. That is, if the toner particle diameter is small even with the same amount of adhesion, the image density can be increased. On the other hand, when the toner particle diameter is smaller than 4 μm, handling becomes extremely difficult, which has a bad effect on the human body. From the above, the toner particle diameter is preferably 7 μm or less.
[0043]
Generally, the darker the black of the toner itself, the higher the image density of an image formed with such a toner, and thus the smaller the amount of toner for obtaining a certain image density. In order to increase the blackness of the toner itself, it is necessary to design the toner with a high pigment and a high dispersion.
[0044]
When a large amount of carbon black is contained in the toner, scattering of incident light increases, and the blackness of the toner can be improved. However, since carbon black is a conductive substance, if it is contained in an excessively large amount, the charging ability of the toner is lowered, and problems such as fogging and toner scattering occur. In addition, the dispersibility of carbon black also deteriorates.
[0045]
Also, the method of improving the dispersibility of carbon black in the toner also increases the scattering of incident light and improves the blackness of the toner itself. In order to achieve high dispersion, a method of dispersing the pigment by applying a high shear at the time of forming the toner may be used. However, in this method, molecular cutting of the binder resin is likely to occur, and other properties as a toner (fixing property) ) May be impaired. Therefore, the above-mentioned problem can be solved by using a master batch that has already achieved high dispersion.
[0046]
When used for two-component development, this toner, glass beads or oxidized or unoxidized iron powder, uncoated carrier such as ferrite, or iron, nickel, cobalt, ferrite and other magnetic materials, acrylic polymer, A developer is mixed with a coated carrier coated with a polymer such as a fluororesin-based polymer, polyester, or modified silicone resin. The carrier generally has an average particle size of 30 to 500 μm, and the toner concentration (T / D) is preferably 1 to 15%.
[0047]
The obtained toner can be applied to all known electrostatic image developing methods. For example, a two-component developing method such as a cascade method, a magnetic brush method, or a microtoning method; a one-component developing method using a magnetic toner such as a conductive one-component developing method, an insulating one-component developing method, or a jumping developing method; Method and fur brush method; non-magnetic one-component developing method in which the toner is conveyed to a developing unit by being held on a toner carrier by electrostatic force, and is developed; Used for law. Further, it can also be used in a toner jet type image forming method.
[0048]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited thereto.
−Volume resistance measurement method−
70 g of the master batch is pulverized by a pulverizer (A10 manufactured by IKA) for 60 seconds and passed through a 300-mesh sieve. Next, 1.0 g of the material passed through the sieve is weighed and pressed by a press molding machine to form a circular disk. The volume resistance of the disk is measured with a measuring device (Lorester GP manufactured by Mitsubishi Chemical Corporation).
-Measuring method of toner triboelectric charge-
FIG. 1 is an explanatory view of an apparatus 1 for measuring a triboelectric charge amount. About 0.5 to 1.5 g of a two-component developer collected from a developing sleeve of a copying machine or a printer is placed in a metal measuring container 12 having a 500-mesh screen 13 at the bottom, and a metal lid 14 is provided. . At this time, the weight of the entire measurement container 12 is weighed and set as W1 (g). Next, in the suction device 11 (at least the portion in contact with the measurement container 12 is at least an insulator), the air is suctioned from the suction port 17 and the air volume control valve 16 is adjusted to adjust the pressure of the vacuum gauge 15 to 250 mmAq. In this state, suction is sufficiently performed, preferably for 2 minutes, to remove the toner by suction. The potential of the electrometer 19 at this time is set to V (volt). Here, reference numeral 18 denotes a capacitor having a capacity of C (mF). Further, the weight of the entire measurement container after suction is weighed to be W2 (g). The triboelectric charge (mC / kg) of this sample is calculated as in the following equation.
Amount of triboelectric charge of sample (mC / kg) = C × V / (W1−W2)
(However, the measurement conditions are 23 ° C. and 60% RH.)
As a carrier used for the measurement, a coated ferrite carrier having carrier particles of 250 to 250 mesh pass and having a mesh size of 350 to 70 mass% is used.
-Measurement method of area ratio of carbon black-
The kneaded product after kneading the toner is cut into a thickness of about 0.2 μm with a cutter such as a microtrome, and a 5000 × photograph is taken with a transmission electron microscope, and a 20 cm × 40 cm image is taken with an image analyzer having a visual field of 40 μm × 80 μm. The area ratio of the aggregate of the colorant in the range was measured. Here, the aggregates having a particle size of 0.05 μm or more were counted. In the case where the amount of aggregate is small and the dispersion is advanced to near the primary dispersion diameter, the area ratio is small. Those having an area ratio of 2.5% or less were determined to be dispersed to near the primary dispersion diameter. The measurement results are shown in Table 1.
−Example of master batch production−
After the binder resin and carbon black were uniformly mixed with a super mixer, the mixture was melt-kneaded at 100 ° C. for 30 minutes using an MS type pressure kneader (manufactured by Moriyama). Next, after cooling the kneaded material, it was pulverized to 1 mm or less by a coarse pulverizer to obtain a master batch.
In the melt-kneading, if kneading is performed at a high kneading temperature, the viscosity of the resin decreases, so that it is difficult to obtain a shear and the dispersibility deteriorates. Conversely, when kneading is performed at a low kneading temperature, the dispersibility becomes good.
[0049]
In addition, when the kneading time is increased, the shearing force applied to the resin and the carbon black increases, so that the dispersibility is improved. Conversely, if the kneading time is short, the dispersibility becomes poor.
[0050]
Embodiment 1
Masterbatch 1 was obtained according to the above production example by using 50 parts by weight of polyester resin manufactured by Sanyo Chemical Co., Ltd. (volume resistance value: 2 × 109 Ω · cm) and 50 parts by weight of # 970 manufactured by Mitsubishi Chemical Corporation as carbon black. The area ratio of carbon black was measured by the volume resistance value and TEM observation of the obtained masterbatch. Table 1 shows the results.
[0051]
Embodiment 2
A masterbatch 2 was obtained in the same manner as in Preparation Example 1 except that # 25 manufactured by Mitsubishi Chemical Corporation was used as carbon black, and the same measurement as in Example 1 was performed. Table 1 shows the results.
[0052]
Embodiment 3
A master batch 3 was obtained in the same manner as in Example 1 except that the conditions for melt-kneading were changed, and the same measurement as in Example 1 was performed. Table 1 shows the results.
[0053]
Embodiment 4
A masterbatch 4 was obtained in the same manner as in Example 1 except that the conditions for melt-kneading were changed, and the same measurement as in Example 1 was performed. Table 1 shows the results.
[0054]
Embodiment 5
A masterbatch 5 was obtained in the same manner as in Example 1 except that the conditions for melt-kneading were changed, and the same measurement as in Example 1 was performed. Table 1 shows the results.
[0055]
Embodiment 6
A masterbatch 6 was obtained in the same manner as in Example 1 except that the conditions for melt-kneading were changed, and the same measurement as in Example 1 was performed. Table 1 shows the results.
[0056]
Embodiment 7
A masterbatch 7 was obtained in the same manner as in Example 1 except that a styrene-acrylic resin (volume resistance value: 1.5 × 10 8 Ω · cm) manufactured by Mitsui Chemicals, Inc. was used as the binder resin, and the same measurement as in Example 1 was performed. Was done. Table 1 shows the results.
[0057]
Embodiment 8
A master batch 8 was obtained in the same manner as in Example 7 except that the conditions for melt-kneading were changed, and the same measurement as in Example 1 was performed. Table 1 shows the results.
[0058]
[Comparative Example 1]
A masterbatch 9 was obtained in the same manner as in Example 7 except that the conditions for melt-kneading were changed, and the same measurement as in Example 1 was performed. Table 1 shows the results.
[0059]
[Table 1]

-Example of toner production-
[0060]
Embodiment 9
80 parts of binder resin (polyester resin manufactured by Sanyo Chemical Co., Ltd.)
Master batch 1 20 copies
2 parts of Spillon Black TRH made by Hodogaya Chemical Co., Ltd.
Polypropylene wax NP505 manufactured by Mitsui Chemicals, Inc. 4 parts
After uniformly mixing the above materials with a supermixer, kneading with a twin-screw extruder at an internal temperature of 150 ° C, finely pulverizing the cooled product with a jet mill, classifying with a dispersion separator, and coloring agent-containing particles having an average particle size of 6.5 μm. Got. One part of commercially available silica (primary average particle size: 0.1 μm, hydrophobicity: 50%) was mixed and dispersed in the colorant-containing particles to obtain Toner 1.
[0061]
Embodiment 10
A toner 2 was obtained in the same manner as in Example 9, except that the master batch 2 was used.
[0062]
Embodiment 11
A toner 3 was obtained in the same manner as in Example 9 except that the master batch 3 was used.
[0063]
Embodiment 12
A toner 4 was obtained in the same manner as in Example 9, except that the master batch 4 was used.
[0064]
Embodiment 13
80 parts of binder resin (styrene-acrylic resin manufactured by Mitsui Chemicals, Inc.)
Master batch 7 20 copies
2 parts of Spillon Black TRH made by Hodogaya Chemical Co., Ltd.
Polypropylene wax NP505 manufactured by Mitsui Chemicals, Inc. 4 parts
After uniformly mixing the above materials with a supermixer, kneading with a twin-screw extruder at an internal temperature of 150 ° C, finely pulverizing the cooled product with a jet mill, classifying with a dispersion separator, and coloring agent-containing particles having an average particle size of 6.5 μm. Got. One part of commercially available silica (primary average particle diameter: 0.1 μm, hydrophobicity: 50%) was mixed and dispersed in the colorant-containing particles to obtain toner 5.
[0065]
Embodiment 14
A toner 6 was obtained in the same manner as in Example 13, except that the master batch 8 was used.
[0066]
[Comparative Example 2]
A toner 7 was obtained in the same manner as in Example 9 except that the master batch 5 was used.
[0067]
[Comparative Example 3]
A toner 8 was obtained in the same manner as in Example 9 except that the master batch 6 was used.
[0068]
[Comparative Example 4]
A toner 9 was obtained in the same manner as in Example 13, except that the master batch 9 was used.
[0069]
[Comparative Example 5]
A toner 10 was obtained in the same manner as in Example 9, except that the average particle size was changed to 7.5 μm.
-Evaluation of toner-
(1) Blackness
Ferrite carrier (F-150, manufactured by Powdertech Co., Ltd.) was uniformly mixed with toners 1 to 10, and the obtained developer was mounted on a commercial copying machine (AR-505, Sharp Corp.). Was done.
[0070]
A developer is mounted on a copying machine AR-505 (manufactured by Sharp Corporation), a black image is taken over the entire surface while changing the toner density in the developer, and the image density is measured using an optical reflection density RD-915 (reflection densitometer). (Macbeth Co., Ltd.), and a toner density exceeding 1.40 was determined.
[0071]
◎: less than 3.5%
○: 3.5% or more and less than 4%
△: 4% or more and less than 5%
×: 5% or more
Table 2 shows the results.
[0072]
(2) Charging properties
To 4 parts of each of toners 1 to 10, 96 parts of a ferrite carrier (F-150, manufactured by Powdertech Co., Ltd.) is uniformly mixed, and a developer is mounted on a copying machine AR-505 (manufactured by Sharp Corporation). The amount of charge in an environment with a humidity of 50% was measured, and then the amount of charge in an environment with a temperature of 35 ° C. and a humidity of 80% was measured. The rate of change
{(Charge amount at 25 ° C./50%)−(charge amount at 35 ° C./80%)}/(charge amount at 25 ° C./50%) was determined based on the following criteria.
[0073]
◎: less than 5%
：: 5% or more and less than 10%
△: 10% or more and less than 20%
×: 20% or more
Table 2 shows the results.
[0074]
[Table 2]

[0075]
【The invention's effect】
As described above, according to the present invention, it is possible to evaluate whether or not a good toner masterbatch is used, and a good toner masterbatch that can achieve a high image density even with a small amount of toner, and a method using the same. Thus, the obtained electrophotographic toner can be obtained.
[Brief description of the drawings]
FIG. 1 is a perspective view schematically showing an overall configuration of a triboelectric charge amount measuring device.
[Explanation of symbols]
1 Friction charge measurement device

Claims (4)

An evaluation method of a master batch comprising at least a binder resin and a coloring agent,
It is determined whether or not a relationship that satisfies −6 ≦ logRm−logRr holds between the volume resistance Rr (Ω · cm) of the binder resin and the product volume resistance Rm (Ω · cm) of the master batch. A method for evaluating a masterbatch for toner, comprising: A master batch comprising at least a binder resin and a coloring agent,
Carbon black having a primary particle size of 10 nm to 100 nm is contained as a colorant in the masterbatch at a ratio of 30 to 60 parts by weight, and the volume resistance Rr (Ω · cm) of the binder resin and the product of the masterbatch A masterbatch for toner, wherein a relationship satisfying -6 ≦ logRm−logRr is established between the masterbatch and the volume resistance Rm (Ω · cm). A toner comprising the toner master batch according to claim 2. 4. The toner according to claim 3, wherein the volume average particle diameter is 7 μm or less.

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