JP3832683B2 - Developer - Google Patents

Description

【００２３】
（合成例４）
トナーＤ
外添剤として、疎水性シリカ微粒子Ｒ−９７２ １．２部の代わりに、疎水性チタニア微粒子Ｔ−８０５（日本アエロジル社製）１．２部を用いた以外は、合成例１と同様にしてトナーを得た。
【００２４】
（実施例１）
コーティング材として、スチレン２０重量％、メチルメタクリレート７８．０重量％及び４−ビニルピリジン２．０重量％よりなる含窒素メタクリレート共重合体（Ｍｎ＝５０，０００、Ｍｗ＝１００，０００）を用い、トルエンに溶解して２０％溶液を調製した。得られた溶液をコーティング溶液として使用した。
コア材として、平均粒径５０μｍのＣｕ−Ｚｎ系フェライトキャリア粒子（Ｆ−３００、パウダーテック社製）を使用し、上記コーティング溶液をコア材に対して、１．２重量部添加し被覆キャリアを得た。
上記キャリアと、前記トナーＡを用い、トナー濃度５．０％の現像剤に調製した。（株）リコー社製複写機ｉｍａｇｉｏ ＤＡ３５５を用い、耐刷評価を行った。また、その際の画像表価結果を表１に記す。
【００２５】
（実施例２）
実施例１のキャリアと、前記トナーＢを用い、実施例１と同様にして現像剤を得た。この現像剤を実施例１と同様にして耐刷評価を行い、その結果を表１に記した。
【００２６】
（実施例３）
実施例１のキャリアと、前記トナーＣを用い、実施例１と同様にして現像剤を得た。この現像剤を実施例１と同様にして耐刷評価を行い、その結果を表１に記した。
【００２７】
（実施例４）
実施例１のキャリアと、前記トナーＤを用い、実施例１と同様にして現像剤を得た。この現像剤を実施例１と同様にして耐刷評価を行い、その結果を表１に記した。
【００２８】
（実施例５）
実施例１のキャリアで、コア材として用いたＣｕ−Ｚｎ系フェライトキャリア粒子（Ｆ−３００、パウダーテック社製）の代わりに、Ｌｉ系フェライトキャリア粒子を使用したこと以外は、実施例１と同様にして被覆キャリアを得た。このキャリアと、前記トナーＡを用い、実施例１と同様にして現像剤を得た。この現像剤を実施例１と同様にして耐刷評価を行い、その結果を表１に記した。
【００２９】
（実施例６）
実施例１のコーティング剤中にカーボンブラック重量５．０％含有させること以外は、実施例１と同様にして被覆キャリアを得た。このキャリアと、前記トナーＡを用い、実施例１と同様にして現像剤を得た。この現像剤を実施例１と同様にして耐刷表価を行い、その結果を表１に記した。
【００３０】
（実施例７）
コーティング材として、シリコーン系樹脂（商品名：ＳＲ−２４１１、固型分２０重量％、東レ・ダウコーニング・シリコーン社製）を使用し、実施例１のキャリア芯材に対し、０．７重量％コーティングし、さらに２００℃で２時間焼付けを行い、被覆キャリアを得た。このキャリアと、前記トナーＡを用い、実施例１と同様にして現像剤を得た。この現像剤を実施例１と同様にして耐刷表価を行い、その結果を表１に記した。
【００３１】
（実施例８）
コーティング材として、スチレン２０重量％、メチルメタクリレート７５．０重量％及び４−ビニルピリジン５．０重量％よりなる含窒素メタクリレート共重合体（Ｍｎ＝５０，０００、Ｍｗ＝１００，０００）５０重量％と、メチルメタアクリレート／スチレン／パーフロロオクチルエチルメタアクリレート（重量比８０／１０／１０）含フッ素メタクリレート共重合体（重量平均分子量約３万）５０重量％を用い、トルエンに溶解して２０％溶液を調製した。得られた溶液をコーティング溶液として使用した以外は、実施例１と同様にして被覆キャリアを得た。このキャリアと、前記トナーＡを用い、実施例１と同様にして現像剤を得た。この現像剤を実施例１と同様にして耐刷表価を行い、その結果を表１に記した。
【００３２】
（比較例１）
実施例１のキャリアで、前記コーティング溶液をコア材に対し、２．４重量部添加した以外は、実施例１と同様にして被覆キャリアを得た。このキャリアと、前記トナーＡを用い、実施例１と同様にして現像剤を得た。この現像剤を実施例１と同様にして耐刷表価を行い、その結果を表１に記した。
【００３３】
【表１】

Ｑ１：トナーと芯材粒子との帯電量（μｃ／ｇ）
Ｑ２：トナーとコートキャリアとの帯電量（μｃ／ｇ）
Ｑ３：耐刷試験１５万枚後の帯電量（μｃ／ｇ）
Ｑ４：耐刷試験３０万枚後の帯電量（μｃ／ｇ）
（耐刷試験１５万枚で非常に良好な結果が出たものを続行した。）
ＩＤ：画像濃度
【００３４】
【発明の効果】
以上、詳細かつ具体的に説明から明らかなように、本発明においては、トナーと芯材粒子との帯電量と、トナーとコートキャリアとの帯電量との差（｜Ｑ１−Ｑ２｜）を小さくすることにより、所望の、Ｑ２とＱ３との差の小さい、帯電安定性の優れた現像剤を得ることができるという極めて優れた効果が発揮される。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a developer used for developing an electrostatic image in an electrophotographic copying machine, a printer, a fax machine, and the like, and more particularly to an improved developer composed of a toner and a carrier.
[0002]
[Prior art]
A method of visualizing image information through an electrostatic latent image such as electrophotography is currently used in various fields. In electrophotography, an electrostatic latent image is formed on a photoreceptor by charging and exposure processes, the electrostatic latent image is developed with a developer containing toner, and visualized through a transfer and fixing process. The developer used here includes a two-component developer composed of a toner and a carrier, and a one-component developer used solely for the toner such as a magnetic toner. The two-component developer is a carrier agitated by a developer. -Since the functions such as transport and charging are shared and the functions are shared as a developer, it has a feature such as good controllability and is widely used at present. In particular, a developer using a carrier coated with a resin has excellent charge controllability, and is relatively easy to improve environment dependency and stability over time.
[0003]
As a developing method, the cascade method has been used in the past, but at present, the magnetic brush method using a magnetic roll as a developer conveying unit is the mainstream. In the magnetic brush method using a two-component developer, a decrease in image density due to developer charge deterioration, significant background stains, image roughness due to carrier adhesion to the image, carrier consumption, and image density unevenness. There are problems such as occurrence.
The mechanism of carrier adhesion to the image is that the resistance of the carrier decreases, so that induced charges are injected into the image area and the carrier adheres, or the upper limit control of the charge amount of the carrier is insufficient. It is considered that the charge amount of the carrier becomes excessive and the carrier adheres to the edge portion.
[0004]
In recent years, negatively charged organic photoreceptors have become widespread, and even in the case of inorganic photoreceptors, reversal development, in which an electrostatic charge image is recorded using a laser or the like, has been frequently used, not to mention negatively charged toners. Even in the positively charged toner, the demand for high-quality developers is high. Therefore, it is desirable that the charging performance of the carrier can be freely controlled according to the charging polarity and charging strength of the toner. Furthermore, with recent trends in miniaturization and speedup of copiers and printers, it has become necessary to reduce the size of developing machines themselves and to increase the speed of development, and demands for improvements such as improved mechanical strength and stability over time have become even stronger. .
[0005]
In recent years, studies on resin-coated carriers that satisfy these required characteristics have been actively conducted, and in particular, many carrier coating treatment methods have been proposed as methods for controlling the chargeability of carriers. For example, a method of coating a carrier with at least two kinds of resins having different charging polarities (Japanese Patent Laid-Open Nos. 64-29865 and 64-29866) has been proposed. When a resin having (+) polarity and a resin having (−) polarity are mixed, the triboelectric charge imparting ability on the carrier surface is not uniform, the toner charge distribution becomes wide, and image quality defects such as image density unevenness. It is easy to invite. In addition, when multiple layers are formed by sequentially coating resins with different charging polarities, the contribution of the outermost layer and the intermediate layer to the toner charge is expected to vary depending on the mixing time, and the toner charge amount is stabilized within an appropriate range. It is difficult to do.
[0006]
In these resin-mixed coated carriers, generally, the chargeability of the carrier is controlled by the mixing ratio of the resin having the ability to impart charge to the toner and the resin that suppresses the charging ability of the resin (hereinafter referred to as a charge-suppressing resin) However, heretofore, there has been no invention that regulates the chargeability of the charge-suppressing resin itself, leaving problems in charge controllability and charge stability.
[0007]
On the other hand, to realize downsizing and high-speed development of the developing machine, the charge rising speed is fast even with a small amount of carrier, and the toner charge amount distribution width is narrowed by mixing with toner for a short time, which is suitable for development. It is desired to design a carrier and toner that can stably obtain a sufficient image density by increasing the amount of toner in the charge amount range.
[0008]
[Problems to be solved by the invention]
The present invention provides an electrostatic charge image developer that solves the above-mentioned problems, has excellent temporal stability, and can obtain high image quality density and good image quality not only in normal development but also in high-speed development. It is something to be offered.
[0009]
[Means for Solving the Problems]
The above-described problem is at least 2 of the present invention (1) consisting of “ a toner containing at least silica as an external additive and a polarity control agent (excluding magnetic toner) and a coated carrier having a resin coating layer on the core particle. When the charge amount (μc / g) between the toner and the core particle is Q1 and the charge amount (μc / g) between the toner and the coat carrier is Q2, Q1 is the core developer. 95 parts by weight of particles and 5 parts by weight of the toner, and Q2 is a charge amount measured by a blow-off method after mixing 95 parts by weight of the carrier and 5 parts by weight of the toner with a tumbler mixer for 10 minutes, A two-component developer for developing an electrostatic image characterized by satisfying the following general formulas (1) and (2);
| Q1-Q2 | ≦ 10 General formula (1)
| Q2 | ≧ 15 Formula (2) ”,
(2) “A two-component developer for developing an electrostatic charge image according to item (1), which satisfies the following general formula (3);
| Q2 | ≦ 30 Formula (3) ”,
(3) "The two-component developer for developing electrostatic images according to (1) above, wherein the toner contains a chromium-containing azo dye",
( 4 ) "The two-component developer for developing electrostatic images according to (1) above, wherein the core particles are Li-based ferrite particles",
( 5 ) "The two-component developer for developing electrostatic images according to (1) above, wherein the resin coating layer contains a resistance adjusting agent",
( 6 ) "The two-component developer for developing electrostatic images according to (1) above, wherein the resin coating layer contains at least a silicone resin",
( 7 ) The problem is solved by the “two-component developer for developing electrostatic images according to (1) above, wherein the resin coating layer comprises two or more kinds of resins and contains at least a fluororesin”. Hereinafter, the present invention will be described in detail.
[0010]
As a result of intensive studies, the present inventors have found that the above-described problems of the invention can be solved by making the chargeability of the coated carrier substantially the same as that of the core particles. That is, as described above, it is considered that the chargeability at the time of coating and that at the time of non-coating are almost the same, so that stable chargeability can be obtained even if the carrier surface fluctuates for some reason. A carrier excellent in charge rising speed and stability over time could be obtained. Conventionally, the difference in chargeability between the carrier itself and the core particles in the coat carrier has not been defined. For this reason, it is assumed that the charging property of the core particles and other additives will appear with the passage of time, resulting in a problem that the charge amount distribution of the toner becomes wider and the charge rising speed of the additional toner becomes slower. Moreover, such a problem has been confirmed by the present inventors in a system in which the toner consumption speed is high due to high-speed development. In addition, it is difficult to uniformly coat the surface of the core material particles during the production of the carrier, particularly in the coating process, and more or less uneven coating occurs. Conventionally, even on the surface of one carrier at the production stage, Even in individual carriers, a large difference in chargeability usually occurred.
[0011]
A feature of the present invention is that when the charge amount (μc / g) between the toner and the core material particles is Q1, and the charge amount (μc / g) between the toner and the coat carrier is Q2,
| Q1-Q2 | ≦ 10, | Q2 | ≧ 15
It is to satisfy the range. Outside this range, there is a large difference in chargeability between the core particle and the coat carrier, and the chargeability of the core particle appears over time as in the prior art, so that the toner charge amount distribution is expanded and the charge amount of the additional toner is increased. As a result, the rising speed is lowered, and as a result, a reduction in image density and density unevenness are likely to occur during high-speed development.
[0012]
The coating resin in the present invention can be widely used in conventional products regardless of the type. For example, when Cu—Zn-based ferrite is used as the core material particles, a styrene-based resin, an epoxy resin, a silicone resin, or the like is preferably used. In addition, the measurement of the triboelectric charge amount with the core particles and the coat carrier is carried out by mixing 5 parts by weight of the toner with respect to 95 parts by weight of the carrier with a tumbler mixer for 10 minutes, and then using a blow-off charge amount measuring machine TB-200 manufactured by Toshiba Chemical Corporation. It was used and evaluated.
[0013]
Further, these coated carriers are characterized in that, when mixed with toner, the absolute value of the charge amount is in the range of 30 μc / g or less. Here, if it exceeds 30 μc / g, it is not good because sufficient image density cannot be obtained. Moreover, it is preferable that it exists in the range of 15 microc / g or more. Here, if it is less than 15 μc / g, it causes fog and uneven image density, which is not good.
[0014]
The amount of the coating resin is usually 0.2 to 0.3% by weight based on the total amount of the resin relative to the carrier. In the developer of the present invention, when the resin coating layer contains a silicone resin or a fluororesin, it has been found that the stain resistance of the agent is greatly improved, these resins have low surface energy, good releasability, The carrier coated with these resins with good stain resistance is less likely to be contaminated with the toner and toner components even if it is stirred with the toner for a long time, and the life of the developer is improved.
[0015]
As the core material particles used in the present invention, iron powder, ferrite, and magnetite granule that are usually used can be used, but when the present inventors used Li-based ferrite particles in the core material in particular, It has been found that the developer has excellent charge stability. Since the Li-based ferrite particles have high chargeability among the core material particles, even if they are coated, there is not much difference in charge amount from the coated carrier. A particle size of about 30 to 200 μm is usually used.
[0016]
In the present invention, it has been found that the charge amount of the coated carrier approaches the charge amount in an uncoated state by including a resistance adjusting agent in the resin coating layer of the carrier. In the present invention, a conventionally used resistance adjusting agent can be used. In other words, metals such as Fe, Cu, Sn, Zn, Pb, and Al, or metal oxides such as alloys, various ferrites, magnetite, titanium oxide, tin oxide, graphite, carbon black, etc. And fine powders such as carbon compounds. Among these, carbon black is particularly preferable.
[0017]
When the carrier of the present invention is produced, a known coating method such as a spray drying method or a dipping method, or a dry coating method in which core particles and coating resin particles are mixed, heated, and cooled in a dry state. Are all applicable.
As the toner polarity control agent according to the present invention, those conventionally used can be used. Among them, in particular, a developer using a chromium-containing azo dye obtained excellent results in charge stability. The toner whose polarity is controlled by the chromium-containing azo dye can, of course, obtain good chargeability even with respect to the coated carrier, but particularly shows a high charge amount with respect to the core particle, and the core particle and the coat in the charge amount. The difference from the carrier is reduced.
[0018]
In the same sense, as the toner external additive of the present invention, commercially available products can be widely used. Conventionally used silica has a characteristic of being negatively charged. On the other hand, since titania has neutral charging characteristics, it does not show a specific charging behavior with respect to both the core material and the coating material, and can be said to be a material suitable for the present invention.
[0019]
【Example】
EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.
(Synthesis Example 1)
Toner A
Styrene-methyl acrylate copolymer (50 parts: 50 parts) 100 parts 3,5-di-t-butylsalicylic acid zinc complex (polarity control agent) 2 parts carbon black (colorant; manufactured by Mitsubishi Kasei Kogyo Co., Ltd. # 44 ) 3 parts The above composition was premixed with a Henschel mixer (Mitsui Miike Seisakusho: HENSHEL-FM20B modified machine), this was heat kneaded with a 100 ° C. roll mill for 30 minutes, cooled, and the cooled product was finely mixed with a jet mill. Fine particles having a volume average particle diameter of 5.8 μm were obtained by pulverization and classification. To 100 parts of this classified product, 1.2 parts of hydrophobic silica fine particles R-972 (manufactured by Nippon Aerosil Co., Ltd.) were externally mixed to obtain a toner.
[0020]
(Synthesis Example 2)
Toner B
Synthetic Example 1 except that 2 parts of chromium chain of 3,5-di-t-butylsalicylic acid was used instead of 2 parts of zinc complex of 3,5-di-t-butylsalicylic acid as the polarity control agent. A toner was obtained in the same manner.
[0021]
(Synthesis Example 3)
Toner C
A toner was obtained in the same manner as in Synthesis Example 1 except that 2 parts of the chromium-containing azo dye described below was used instead of 2 parts of the zinc complex of 3.5-di-t-butylsalicylic acid as the polarity control agent.
[0022]
[Chemical 1]

[0023]
(Synthesis Example 4)
Toner D
As an external additive, in the same manner as in Synthesis Example 1, except that 1.2 parts of hydrophobic titania fine particles T-805 (manufactured by Nippon Aerosil Co., Ltd.) were used instead of 1.2 parts of hydrophobic silica fine particles R-972. A toner was obtained.
[0024]
Example 1
As a coating material, a nitrogen-containing methacrylate copolymer (Mn = 50,000, Mw = 100,000) composed of 20% by weight of styrene, 78.0% by weight of methyl methacrylate and 2.0% by weight of 4-vinylpyridine was used. A 20% solution was prepared by dissolving in toluene. The resulting solution was used as a coating solution.
As the core material, Cu—Zn ferrite carrier particles (F-300, manufactured by Powdertech) having an average particle diameter of 50 μm are used, and 1.2 parts by weight of the above coating solution is added to the core material to provide a coated carrier. Obtained.
Using the carrier and toner A, a developer having a toner concentration of 5.0% was prepared. Printing durability was evaluated using a copying machine “imageo DA355” manufactured by Ricoh Co., Ltd. In addition, Table 1 shows the image price results at that time.
[0025]
(Example 2)
Using the carrier of Example 1 and the toner B, a developer was obtained in the same manner as in Example 1. The developer was evaluated for printing durability in the same manner as in Example 1. The results are shown in Table 1.
[0026]
Example 3
Using the carrier of Example 1 and the toner C, a developer was obtained in the same manner as in Example 1. The developer was evaluated for printing durability in the same manner as in Example 1. The results are shown in Table 1.
[0027]
Example 4
Using the carrier of Example 1 and the toner D, a developer was obtained in the same manner as in Example 1. The developer was evaluated for printing durability in the same manner as in Example 1. The results are shown in Table 1.
[0028]
(Example 5)
The carrier of Example 1 was the same as Example 1 except that Li-based ferrite carrier particles were used instead of the Cu—Zn-based ferrite carrier particles (F-300, manufactured by Powdertech) used as the core material. Thus, a coated carrier was obtained. Using this carrier and the toner A, a developer was obtained in the same manner as in Example 1. The developer was evaluated for printing durability in the same manner as in Example 1. The results are shown in Table 1.
[0029]
(Example 6)
A coated carrier was obtained in the same manner as in Example 1 except that the coating agent of Example 1 contained 5.0% by weight of carbon black. Using this carrier and the toner A, a developer was obtained in the same manner as in Example 1. The developer was subjected to a printing plate price in the same manner as in Example 1, and the results are shown in Table 1.
[0030]
(Example 7)
As a coating material, a silicone resin (trade name: SR-2411, solid content 20 wt%, manufactured by Toray Dow Corning Silicone Co., Ltd.) was used, and 0.7 wt% with respect to the carrier core material of Example 1. Coating was performed and baking was further performed at 200 ° C. for 2 hours to obtain a coated carrier. Using this carrier and the toner A, a developer was obtained in the same manner as in Example 1. The developer was subjected to a printing plate price in the same manner as in Example 1, and the results are shown in Table 1.
[0031]
(Example 8)
As a coating material, nitrogen-containing methacrylate copolymer (Mn = 50,000, Mw = 100,000) consisting of 20% by weight of styrene, 75.0% by weight of methyl methacrylate and 5.0% by weight of 4-vinylpyridine is 50% by weight. And 50% by weight of a methyl methacrylate / styrene / perfluorooctylethyl methacrylate (weight ratio 80/10/10) fluorine-containing methacrylate copolymer (weight average molecular weight of about 30,000) and dissolved in toluene to give 20% A solution was prepared. A coated carrier was obtained in the same manner as in Example 1 except that the obtained solution was used as a coating solution. Using this carrier and the toner A, a developer was obtained in the same manner as in Example 1. The developer was subjected to a printing plate price in the same manner as in Example 1, and the results are shown in Table 1.
[0032]
(Comparative Example 1)
A coated carrier was obtained in the same manner as in Example 1 except that 2.4 parts by weight of the coating solution was added to the core material in the carrier of Example 1. Using this carrier and the toner A, a developer was obtained in the same manner as in Example 1. The developer was subjected to a printing plate price in the same manner as in Example 1, and the results are shown in Table 1.
[0033]
[Table 1]

Q1: Charge amount between toner and core particles (μc / g)
Q2: Charge amount between toner and coat carrier (μc / g)
Q3: Charge amount after 150,000 sheets of printing durability test (μc / g)
Q4: Charge amount after 300,000 printing tests (μc / g)
(Continued to produce a very good result with 150,000 sheets of printing durability test.)
ID: Image density [0034]
【The invention's effect】
As described above in detail and specifically, in the present invention, the difference (| Q1-Q2 |) between the charge amount between the toner and the core material particle and the charge amount between the toner and the coat carrier is reduced. By doing so, the extremely excellent effect that a desired developer having a small difference between Q2 and Q3 and excellent charging stability can be obtained.

Claims (7)

A two-component developer comprising at least a toner (excluding a magnetic toner) containing silica as an external additive and a polarity control agent, and a coat carrier having a resin coating layer on core material particles, the toner and the core When the charge amount (μc / g) with the material particles is Q1, and the charge amount (μc / g) between the toner and the coat carrier is Q2, Q1 is 95 parts by weight of the core particles and 5 parts by weight of the toner. Q2 is a charge amount measured by the blow-off method after 95 parts by weight of the carrier and 5 parts by weight of the toner are mixed for 10 minutes by a tumbler mixer, respectively. The following general formulas (1) and (2) 2 component developer for developing an electrostatic charge image.
| Q1-Q2 | ≦ 10 General formula (1)
| Q2 | ≧ 15 Formula (2) The two-component developer for developing an electrostatic charge image according to claim 1, wherein the following general formula (3) is satisfied.
| Q2 | ≦ 30 Formula (3)   2. The two-component developer for developing an electrostatic charge image according to claim 1, wherein the toner contains a chromium-containing azo dye.   2. The two-component developer for developing an electrostatic charge image according to claim 1, wherein the core material particles are Li-based ferrite particles.   2. The two-component developer for developing an electrostatic charge image according to claim 1, wherein the resin coating layer contains a resistance adjusting agent.   2. The two-component developer for developing electrostatic images according to claim 1, wherein the resin coating layer contains at least a silicone resin.   2. The two-component developer for developing an electrostatic charge image according to claim 1, wherein the resin coating layer comprises two or more kinds of resins and contains at least a fluororesin.