JPH0648388B2 - Dry developer - Google Patents
Dry developerInfo
- Publication number
- JPH0648388B2 JPH0648388B2 JP60167512A JP16751285A JPH0648388B2 JP H0648388 B2 JPH0648388 B2 JP H0648388B2 JP 60167512 A JP60167512 A JP 60167512A JP 16751285 A JP16751285 A JP 16751285A JP H0648388 B2 JPH0648388 B2 JP H0648388B2
- Authority
- JP
- Japan
- Prior art keywords
- titanium oxide
- particles
- toner
- oxide fine
- fine particles
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G9/00—Developers
- G03G9/08—Developers with toner particles
- G03G9/097—Plasticisers; Charge controlling agents
- G03G9/09708—Inorganic compounds
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G9/00—Developers
- G03G9/08—Developers with toner particles
- G03G9/10—Developers with toner particles characterised by carrier particles
- G03G9/113—Developers with toner particles characterised by carrier particles having coatings applied thereto
- G03G9/1139—Inorganic components of coatings
Landscapes
- Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Developing Agents For Electrophotography (AREA)
Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は乾式現像剤に関し、詳しくは２成分系乾式現像
剤にアモルファス，球状の酸化チタン微粒子を含有させ
たことにより長期間にわたり安定的に使用でき、しかも
現像される画像の品質が良好な乾式現像剤に関する。DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a dry developer, and more specifically, it contains a two-component dry developer containing amorphous and spherical titanium oxide fine particles so that it can be stably used for a long period of time. The present invention relates to a dry developer which can be used and has a good quality of developed image.
電子写真法，静電記録法，静電印刷法等により形成され
た電気的潜像を現像して可視画像とするために用いる現
像剤として２成分系乾式現像剤が広く知られている。す
なわち、トナーとキャリアーとから構成される２成分系
乾式現像剤である。A two-component dry developer is widely known as a developer used for developing an electric latent image formed by an electrophotographic method, an electrostatic recording method, an electrostatic printing method or the like into a visible image. That is, it is a two-component dry developer composed of toner and carrier.
これら各成分については要求される特性を満足させるべ
く様々の提案がなされている。たとえば、トナーに磁性
体と導電性微粉末を含有させることにより、トナー粒子
とキャリアー粒子の衝突によってトナーが粉砕され、こ
れがキャリアー表面に融着することによる現像剤の劣化
防止を図る方法がある（特開昭５８−２１６２５６
号）。しかし、この方法は使用する磁性体の分散性が不
十分なため、画質に悪影響を及ぼす等の新たな問題点を
有している。Various proposals have been made for each of these components in order to satisfy the required properties. For example, there is a method of containing a magnetic substance and conductive fine powder in the toner to prevent the deterioration of the developer due to the toner being crushed by the collision of the toner particles and the carrier particles and being fused to the carrier surface ( JP-A-58-216256
issue). However, this method has a new problem that the image quality is adversely affected because the dispersibility of the magnetic material used is insufficient.
また、キャリアー粒子の表面を被覆するために用いる樹
脂組成物についても、いわゆるスペント化によるキャリ
アー粒子の帯電特性の低下を防ぐために、酸化チタン粒
子を含むシリコーン樹脂を被覆層として使用することが
提案されている（特開昭６０−１２５５８号）。しか
し、樹脂組成物中における酸化チタン粒子の分散性が不
十分である上に、キャリアー粒子同士の凝集という問題
については未解決のままである。Further, regarding a resin composition used for coating the surface of carrier particles, it is proposed to use a silicone resin containing titanium oxide particles as a coating layer in order to prevent deterioration of charging characteristics of carrier particles due to so-called spent formation. (JP-A-60-12558). However, the dispersibility of titanium oxide particles in the resin composition is insufficient, and the problem of agglomeration of carrier particles remains unsolved.
本発明は２成分系乾式現像剤における上記問題点を解決
して、耐久性にすぐれ、しかも優れた品質の可視画像を
与える現像剤を提供することを目的としている。An object of the present invention is to solve the above problems in a two-component dry developer and to provide a developer having excellent durability and giving a visible image of excellent quality.
すなわち本発明は、２成分系乾式現像剤において、アモ
ルファス，球状で平均粒子径が0.01〜0.03μｍの酸化チ
タン微粒子を含有することを特徴とする乾式現像剤に関
する。That is, the present invention relates to a two-component dry developer, which is characterized in that it contains amorphous and spherical titanium oxide fine particles having an average particle diameter of 0.01 to 0.03 μm.
本発明に使用するアモルファス，球状の酸化チタン微粒
子は、たとえば特開昭６１−２０１６０４号公報に記載
の方法などによって製造することができる。The amorphous and spherical titanium oxide fine particles used in the present invention can be produced, for example, by the method described in JP-A No. 61-201604.
本発明に用いる酸化チタン微粒子は、その結晶形態がア
モルファスであることがＸ線回析分析により明らかとな
っており、しかも球状である。なお、この酸化チタン微
粒子の平均粒子径は0.01〜0.03μｍのものである。ま
た、酸化チタン微粒子の比表面積についても各種範囲の
ものを使用しうるが、たとえば平均粒子径が0.01〜0.03
μｍの酸化チタン微粒子の場合、約１００〜３００ｍ２
／ｇ（ＢＥＴ法）である。The titanium oxide fine particles used in the present invention have been found by X-ray diffraction analysis to have an amorphous crystal form, and have a spherical shape. The titanium oxide fine particles have an average particle size of 0.01 to 0.03 μm. The titanium oxide fine particles may have various specific surface areas, for example, an average particle diameter of 0.01 to 0.03.
In the case of titanium oxide fine particles of μm, about 100 to 300 m 2
/ G (BET method).
上記酸化チタン微粒子は、トナーおよびキャリアーのい
ずれに加えてもよく、また両者に加えてもよい。The titanium oxide fine particles may be added to either the toner or the carrier, or may be added to both.
前述したように、２成分系乾式現像剤においては、連続
的に運転、使用した場合、トナー粒子とキャリアー粒子
が衝突し、トナーが細かく粉砕され、これがキャリアー
表面に融着して現像剤の劣化を引き起こし、また微粉化
した粒子が周辺に飛散するほか、キャリアー粒子の帯電
性が変化して部分的に吸着力に差が生じて画像にムラを
生じるという欠点があったが、これらの欠点は本発明に
よりことごとく解消される。そのため、現像剤の耐久性
が良好で、可視画像の品質が向上するのである。しか
も、高湿度下においても荷電特性が優れており、凝集し
ないという利点がある。また、本発明に係る酸化チタン
微粒子を用いることにより現像剤の流動性が良好とな
る。As described above, in the two-component dry developer, when continuously operated and used, the toner particles collide with the carrier particles and the toner is finely pulverized, which is fused to the carrier surface and deteriorates the developer. Moreover, in addition to scattering of finely divided particles to the periphery, the chargeability of the carrier particles is changed to cause a partial difference in the adsorption force to cause unevenness in the image, but these drawbacks are The present invention eliminates all problems. Therefore, the durability of the developer is good and the quality of the visible image is improved. Moreover, it has an advantage that it has excellent charging characteristics even under high humidity and does not aggregate. Further, the use of the titanium oxide fine particles according to the present invention improves the fluidity of the developer.
上記の如く、２成分系乾式現像剤に特定の酸化チタン微
粒子を配合するとによって様々の利点が得られるが、該
酸化チタン微粒子をトナーに加えた場合、絶縁性を下げ
る効果が奏されるほか、キャリアー粒子との衝突による
トナー粒子の粉砕、飛散等も有効に防止することができ
る。また、トナー中に磁性体を含む場合、該磁性体の分
散性を向上させる等の効果が奏される。また、酸化チタ
ン微粒子の分散性も良く、流動性にすぐれたトナーが得
られる。なお、トナーの構成成分に関しては既知のもの
を任意に使用でき、たとえばポリスチレンなどの結着樹
脂，カーボンブラックその他の着色剤などのほか上記磁
性体などを適宜加えることができる。トナーへの酸化チ
タン微粒子の配合量については特別な条件はなく、製品
の使用目的等を考慮して適当に決定すればよい。As described above, various advantages can be obtained by blending the specific titanium oxide fine particles with the two-component dry developer, but when the titanium oxide fine particles are added to the toner, the insulating property is lowered, and It is also possible to effectively prevent crushing and scattering of toner particles due to collision with carrier particles. In addition, when the toner contains a magnetic material, the effect of improving the dispersibility of the magnetic material is exhibited. Also, the dispersibility of titanium oxide fine particles is good, and a toner having excellent fluidity can be obtained. As the constituent components of the toner, any known constituents may be used. For example, a binder resin such as polystyrene, carbon black and other colorants, and the above magnetic material may be appropriately added. There is no special condition for the amount of titanium oxide fine particles to be mixed with the toner, and it may be appropriately determined in consideration of the purpose of use of the product.
本発明に係る酸化チタン微粒子はキャリアーに配合する
こともでき、この場合はキャリアーの核粒子の被覆層に
加える。鉄，銅，コバルト，ニッケル，亜鉛，アルミニ
ウム等の金属もしくはこれら金属の酸化物等の粒子や
砂，ガラスビーズ等の無機物粒子が核粒子として用いら
れ、該核粒子の帯電特性などを改善するために、その表
面を合成樹脂で被覆している。このために使用される合
成樹脂としては様々のものがあり、スチレン・メタクリ
レートコポリマー，ポリスチレン等のほか表面張力の低
いシリコーン樹脂等が例示される。さらに、核粒子表面
を合成樹脂で被覆したときの表面物性を改良する目的で
種々の物質が合成樹脂に配合されるが、上記した特定の
酸化チタン微粒子を配合すると、キャリアー粒子同士の
凝集を防止し、キャリアーの偏在という問題が解消され
るほか、酸化チタン微粒子の比重が小さいため、樹脂中
での分散性が良好に保持される。そのため、キャリアー
のスペント化が起り難く、良質の画像を長期にわたり与
えることが可能である。酸化チタン微粒子の配合量はト
ナーの場合と同様に使用目的を考慮して適宜決定すれば
よい。なお、上記核粒子としては一般に平均粒子径が１
０〜１０００μｍ程度のものが使用され、該核粒子への
樹脂組成物の被覆は塗布，噴霧等の常法により行なわれ
る。The titanium oxide fine particles according to the present invention can be incorporated in a carrier, and in this case, they are added to the coating layer of the core particles of the carrier. In order to improve the charging characteristics of the core particles, particles of metals such as iron, copper, cobalt, nickel, zinc, aluminum or particles of oxides of these metals or inorganic particles such as sand and glass beads are used as core particles. In addition, its surface is coated with a synthetic resin. There are various synthetic resins used for this purpose, and examples thereof include styrene-methacrylate copolymer, polystyrene and the like, as well as silicone resins having a low surface tension. Further, various substances are blended with the synthetic resin for the purpose of improving the surface properties when the core particle surface is coated with the synthetic resin. However, when the above specific titanium oxide fine particles are blended, the aggregation of carrier particles is prevented. However, the problem of uneven distribution of carriers is solved, and since the specific gravity of titanium oxide fine particles is small, the dispersibility in the resin is maintained well. Therefore, it is difficult for the carrier to be spent, and it is possible to provide a high-quality image for a long time. The compounding amount of the titanium oxide fine particles may be appropriately determined in consideration of the purpose of use as in the case of the toner. The average particle diameter of the core particles is generally 1
Those having a particle size of about 0 to 1000 μm are used, and the resin composition is coated on the core particles by a conventional method such as coating or spraying.
本発明の乾式現像剤は、トナー粒子とキャリアー粒子と
の衝突により生じるトラブルも極めて少なく、またキャ
リアーの帯電性も安定しており、長期間にわたって安定
した状態で使用でき、現像により形成される可視画像の
品質が良好である。The dry developer of the present invention has very few troubles caused by collision between toner particles and carrier particles, and also has a stable chargeability of the carrier, which can be used in a stable state for a long period of time and formed by development. The image quality is good.
したがって、本発明の乾式現像剤は電子写真法，静電記
録法，静電印刷法等の現像剤として有用である。Therefore, the dry developer of the present invention is useful as a developer for electrophotography, electrostatic recording, electrostatic printing and the like.
次に、本発明を実施例により詳しく説明する。 Next, the present invention will be described in detail with reference to Examples.
実施例１ ポリスチレン６５重量部，カーボンブラック５重量部，
磁性体２０重量部およびアモルファス，球状酸化チタン
（平均粒子径0.02μｍ）５重量部をロールミルで１５０
℃にて２０分間混練したのち、ジェットミルを用いて粉
砕することによって平均粒子径５〜７μｍのトナーを得
た。Example 1 65 parts by weight of polystyrene, 5 parts by weight of carbon black,
20 parts by weight of magnetic material and 5 parts by weight of amorphous and spherical titanium oxide (average particle size 0.02 μm) are 150 by roll mill.
The mixture was kneaded at 20 ° C. for 20 minutes and then pulverized with a jet mill to obtain a toner having an average particle size of 5 to 7 μm.
上記トナー２００ｇとキャリアー（日本鉄粉製、ＥＦＶ
２５０／４００）２８００ｇを混合して２成分系乾式現
像剤を調製した。200 g of the above toner and a carrier (made by Nippon Iron Powder, EFV
250/400) 2800 g was mixed to prepare a two-component dry developer.
この現像剤を電子写真装置（（株）リコー製、ＰＰＣ−
９００）に入れ、耐久１００，０００枚試験を行なっ
た。装置の下に置いた白紙（５cm×５cm）上のトナー飛
散はマクベス濃度計で測定したところ0.11であった。ま
た、トナー中における磁性体の分散性も初期と変らず、
酸化チタン微粒子の凝集も生起していないことが確認さ
れた。This developer is used as an electrophotographic device (PPC-, manufactured by Ricoh Co., Ltd.).
900) and a durability test of 100,000 sheets was performed. The toner scattering on a white paper (5 cm × 5 cm) placed under the apparatus was 0.11. When measured with a Macbeth densitometer. In addition, the dispersibility of the magnetic material in the toner does not change from the initial stage,
It was confirmed that aggregation of titanium oxide fine particles did not occur.
実施例２ 実施例１においてトナー成分としてニグロシン染料５重
量部を加えたことおよび現像剤の耐久試験を１５０，０
００枚としたこと以外は実施例１と同様に行なった。そ
の結果、トナー飛散は0.18であった。また、トナー中に
おける磁性体の分散性や酸化チタン微粒子の凝集性につ
いても実施例１と同様であった。Example 2 In Example 1, 5 parts by weight of a nigrosine dye was added as a toner component, and the durability test of the developer was 150,0.
Example 1 was repeated except that the number of sheets was set to 00. As a result, the toner scattering was 0.18. The dispersibility of the magnetic material in the toner and the aggregability of titanium oxide fine particles were also the same as in Example 1.
比較例１ 実施例２においてトナー成分の酸化チタン微粒子の代り
にＳｎＯ２（三菱金属製、Ｔ−１）を用いたこと以外は
同様に行なった。その結果、白紙上のトナー飛散は0.55
であった。また、この場合は磁性体の分散が悪くなった
ために、可視画像の品質が低下した。Comparative Example 1 The same procedure as in Example 2 was repeated except that SnO 2 (manufactured by Mitsubishi Metals, T-1) was used in place of the titanium oxide fine particles as the toner component. As a result, the toner scattering on the white paper is 0.55.
Met. Further, in this case, the quality of the visible image was deteriorated because the dispersion of the magnetic material was deteriorated.
実施例３ アモルファス，球状の酸化チタン微粒子（平均粒子径0.
02μｍ）１重量部，シリコーン樹脂（信越化学製）１３
０重量部およびトルエン１３０重量部を混合、攪拌して
樹脂溶液を得た。この溶液を粒径５０〜１５０μｍの鋼
製ビーズ５００重量部に塗布してキャリアー粒子を得
た。このときの被覆層の厚さは0.91μｍであった。Example 3 Amorphous and spherical titanium oxide fine particles (average particle diameter of 0.
02 μm) 1 part by weight, silicone resin (manufactured by Shin-Etsu Chemical) 13
0 parts by weight and 130 parts by weight of toluene were mixed and stirred to obtain a resin solution. This solution was applied to 500 parts by weight of steel beads having a particle size of 50 to 150 μm to obtain carrier particles. The thickness of the coating layer at this time was 0.91 μm.
このキャリアー粒子２８００ｇを実施例１で得たトナー
２００ｇと混合して２成分系乾式現像剤を調製した。2800 g of the carrier particles were mixed with 200 g of the toner obtained in Example 1 to prepare a two-component dry developer.
この現像剤を用いて実施例１と同様に試験を行なったと
ころ、１００，０００枚試験におけるコピーの画質に変
化は認められなかった。また、この試験終了後のキャリ
アー粒子について被覆層の厚さを測定したところ0.90μ
ｍであった。When a test was conducted in the same manner as in Example 1 using this developer, no change was observed in the image quality of copies in the 100,000-sheet test. In addition, the thickness of the coating layer was measured for the carrier particles after the completion of this test and found to be 0.90 μm.
It was m.
実施例４ 実施例３で得たキャリアー粒子２８００ｇをトナー（ス
チレン−ｎ−ブチルメタクリレートコポリマー８７重量
部，カーボンブラック１０重量部およびモノアゾ系染料
３重量部、平均粒系６μｍ）２００ｇと混合して現像剤
を得た。Example 4 2800 g of carrier particles obtained in Example 3 were mixed with 200 g of toner (87 parts by weight of styrene-n-butyl methacrylate copolymer, 10 parts by weight of carbon black and 3 parts by weight of monoazo dye, average particle size of 6 μm) and developed. I got an agent.
この現像剤を用いて実施例１と同様に試験を行なったと
ころ、１００，０００枚試験におけるコピーの画質に変
化は認められなかった。また、試験終了後においてもキ
ャリアー粒子の被覆層は殆ど摩耗していなかった。When a test was conducted in the same manner as in Example 1 using this developer, no change was observed in the image quality of copies in the 100,000-sheet test. In addition, the coating layer of carrier particles was scarcely worn even after the test was completed.
比較例２ 実施例３において酸化チタン微粒子として結晶性の酸化
チタン（日本アエロジル社製、Ｐ−２５）を用いたこと
以外は同様にしてキャリアーを調製した。このときの被
覆層の厚さは0.89μｍであった。Comparative Example 2 A carrier was prepared in the same manner as in Example 3, except that crystalline titanium oxide (P-25, manufactured by Nippon Aerosil Co., Ltd.) was used as the titanium oxide fine particles. The thickness of the coating layer at this time was 0.89 μm.
このキャリアー粒子を用いて実施例４と同様にして現像
剤を得た。A developer was obtained in the same manner as in Example 4 by using the carrier particles.
この現像剤を用いて実施例１と同様に試験を行なったと
ころ、１００，０００枚試験後のコピーの画質は低下し
ており、また試験終了後のキャリアー粒子の被覆層の摩
耗も著しかった。When a test was conducted in the same manner as in Example 1 using this developer, the image quality of the copy after the 100,000-sheet test was deteriorated, and the abrasion of the coating layer of carrier particles after the test was also remarkable.
Claims (3)
ス，球状で平均粒子径が0.01〜0.03μｍの酸化チタン微
粒子を含有することを特徴とする乾式現像剤。1. A two-component dry developer, characterized in that it contains amorphous and spherical titanium oxide fine particles having an average particle diameter of 0.01 to 0.03 μm.
径が0.01〜0.03μｍの酸化チタン微粒子を含有する特許
請求の範囲第１項記載の乾式現像剤。2. The dry developer according to claim 1, wherein the toner contains titanium oxide fine particles having an amorphous shape, a spherical shape and an average particle diameter of 0.01 to 0.03 μm.
状で平均粒子径が0.01〜0.03μｍの酸化チタン微粒子を
含有する特許請求の範囲第１項記載の乾式現像剤。3. The dry developer according to claim 1, wherein the coating layer of the carrier contains titanium oxide fine particles having an amorphous shape, a spherical shape and an average particle diameter of 0.01 to 0.03 μm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60167512A JPH0648388B2 (en) | 1985-07-31 | 1985-07-31 | Dry developer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60167512A JPH0648388B2 (en) | 1985-07-31 | 1985-07-31 | Dry developer |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6228772A JPS6228772A (en) | 1987-02-06 |
| JPH0648388B2 true JPH0648388B2 (en) | 1994-06-22 |
Family
ID=15851054
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP60167512A Expired - Fee Related JPH0648388B2 (en) | 1985-07-31 | 1985-07-31 | Dry developer |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0648388B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003098761A (en) * | 2001-09-25 | 2003-04-04 | Ricoh Co Ltd | Carrier for developing electrostatic latent images |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4943506A (en) * | 1987-10-19 | 1990-07-24 | Minolta Camera Kabushiki Kaisha | White toner comprising titanium oxide of specified size |
| JP2943932B2 (en) * | 1989-11-02 | 1999-08-30 | 富士ゼロックス株式会社 | Electrophotographic carrier and method of manufacturing the same |
| JP2623919B2 (en) * | 1990-06-06 | 1997-06-25 | 富士ゼロックス株式会社 | Electrophotographic toner composition |
| JPH04179122A (en) * | 1990-11-09 | 1992-06-25 | Canon Inc | Beam manufacturing method |
| DE69223071T2 (en) * | 1991-01-11 | 1998-03-26 | Canon Kk | Toner for developing electrostatic images |
| JP2995500B2 (en) * | 1991-05-14 | 1999-12-27 | 富士ゼロックス株式会社 | Electrophotographic toner composition |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5342199A (en) * | 1976-09-29 | 1978-04-17 | Hitachi Ltd | Production of globular titania |
| JPS548196A (en) * | 1977-06-21 | 1979-01-22 | Sakai Chem Ind Co Ltd | Amorphous powder |
| US4241042A (en) * | 1978-06-19 | 1980-12-23 | Montedison S.P.A. | Spherical titanium dioxide particles and process of manufacture |
| JPS55155363A (en) * | 1979-05-21 | 1980-12-03 | Minolta Camera Co Ltd | Carrier for dry developer |
| JPS56165652A (en) * | 1980-05-21 | 1981-12-19 | Hitachi Koki Co Ltd | Print paper location scale of laser beam printer |
| JPS56128957A (en) * | 1981-01-23 | 1981-10-08 | Konishiroku Photo Ind Co Ltd | Toner for electrostatic charge development |
| JPS6012558A (en) * | 1983-07-04 | 1985-01-22 | Ricoh Co Ltd | Carrier for electrostatic latent image developer |
-
1985
- 1985-07-31 JP JP60167512A patent/JPH0648388B2/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003098761A (en) * | 2001-09-25 | 2003-04-04 | Ricoh Co Ltd | Carrier for developing electrostatic latent images |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6228772A (en) | 1987-02-06 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |