JP4071338B2 - Non-magnetic one-component developer - Google Patents

Description

【００８１】
【表２】

【００８２】
これらの結果より、本発明の現像剤について、複写画像には白スジは発生せず、帯電性に優れていることが明らかとなった。本発明の現像剤は耐久性および流動性に優れていることがわかる。
比較例１では、１５００枚ぐらいからトナー薄層にスジが発生しはじめ、２０００枚の時点でトナーがこぼれるほどひどくなったため、３０００枚複写後のトナー帯電量の測定を中止した。比較例２では、３０００枚複写後に帯電量の低下が認められ、スリーブのリフレッシュ効果はみられなかった。また、スジの発生している部分にあたる規制ブレードには白い粉のかたまりが付着していた。比較例３では、初期からスリーブ上にトナー薄層が形成されなかったため、初期の複写画像の白スジ評価を行ったのみで、その後の複写は中止した。比較例４では、白スジ等の問題はなかったが、トナーの流動性が高すぎるため、規制部ですり抜けが生じてトナーの帯電の立ち上がりが悪くなり初期の帯電量が低く、３０００枚複写後には大きく帯電量が上昇した。比較例５および６では、初期と３０００枚複写後の帯電量変化が大きく、スリーブのリフレッシュ効果がみられなかった。
【００８３】
【発明の効果】
本発明により、繰り返しの複写によっても複写画像に白スジが発生しない、流動性、帯電性および耐久性に優れた非磁性一成分現像剤を提供することができる。
【図面の簡単な説明】
【図１】 フルカラー画像形成装置の概略構成図を示す。
【符号の説明】
１０：感光体ドラム、１１：帯電ブラシ、１２：クリーナー、２０：レーザ走査光学系、３０：フルカラー現像装置、３２：現像剤担持体（スリーブ）、３３：支軸、３４：現像剤規制部材（ブレード）、４０：中間転写ベルト、４１：支持ローラ、４２：支持ローラ、４３：テンションローラ、４４：テンションローラ、４６：１次転写ローラ、４７：２次転写ローラ、６０：給紙部、６１：給紙トレイ、６２：給紙ローラ、６３：タイミングローラ、６６：エアーサクションベルト、７０：定着器、７１：垂直搬送路。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a developer for developing an electrical latent image in electrophotography and electrostatic printing, and more particularly to a non-magnetic one-component developer.
[0002]
[Prior art]
In general, a two-component developing method and a one-component developing method are known as developing devices, but the one-component developing method is often adopted from the viewpoint of preventing the charging performance from being lowered and reducing the size of the image forming apparatus.
[0003]
There are two types of one-component development systems: magnetic one-component systems and non-magnetic one-component systems, but magnetic one-component development systems usually require the addition of black magnetic powder to the toner. A magnetic one-component development system is preferred. In the non-magnetic one-component development system, the developer regulating member is disposed so as to contact the developer carrying member, and the non-magnetic one-component developer is passed through the gap between the developer carrying member and the developer regulating member. As a result, a thin toner layer is formed on the carrier and charged, and conveyed to the development area as it is, and the electrostatic latent image formed on the electrostatic latent image carrier is developed.
[0004]
In general, inorganic particles such as silica and titania are added (externally added) to the toner as a fluidizing agent in order to improve fluidity. For example, Japanese Patent Application Laid-Open No. 7-43930 reports a technique for externally adding a fluidizing agent having a particle size of 0.05 μm (50 nm) or less to toner particles in a one-component development system. However, in the one-component development method, as described above, the toner particles are charged by passing through the gap (regulator) between the developer carrier and the developer regulating member, so that a large stress is applied to the toner. For this reason, since the fluidizing agent externally added to the toner is embedded in the toner particles, the fluidity cannot be ensured for repeated use. Further, as the fluidizing agent is embedded in the toner surface due to repeated use, the surface state of the toner changes, and it is difficult to maintain stable toner characteristics, particularly chargeability. Furthermore, there is a problem in that the toner component adheres to the developer carrying member and the developer regulating member due to the influence of the stress at the time of charging, thereby impairing charging stability.
[0005]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION An object of the present invention is to provide a non-magnetic one-component developer that is excellent in durability, in particular, charging stability, that can maintain toner characteristics with small change in the surface state of toner particles even when it is repeatedly copied. To do.
[0006]
[Means for Solving the Problems]
  The present invention contains negatively charged toner particles containing at least a binder resin and a colorant, small-sized inorganic fine particles having an average primary particle size of 1 to 70 nm, and strontium titanate fine particles having an average primary particle size of 100 to 500 nm. A non-magnetic one-component developer having a small particle size inorganic fine particle content of 0.3 to 3.0% by weight based on the toner particles, and a strontium titanate fine particle content based on the toner particles. 0.3 to 3.0% by weight, and the small particle size inorganic fine particles are composed of two types of silica and titania, and one of the small particle size fine particles (referred to as “first inorganic fine particles”) of either silica or titania. The average primary particle size is 1 to 40 nm, and the other small particle size fine particles (referred to as “second inorganic fine particles”) are 40 to 70 nm.(The average primary particle diameter is the average of the long diameters of the fine particles observed with a scanning electron microscope (JSM-840A; manufactured by JEOL Ltd.))The content of the first inorganic fine particles is 0.1 to 2.0% by weight based on the toner particles and the content of the second inorganic fine particles is based on the toner particles within the range of the small particle size inorganic fine particles. The present invention relates to a non-magnetic one-component developer characterized by being 0.1 to 2.5% by weight.
[0007]
In the present specification, the average primary particle size of the inorganic fine particles was observed with a scanning electron microscope (JSM-840A; manufactured by JEOL Ltd.), and the average of the long diameters of the fine particles was shown.
[0008]
In the present invention, the surface state of the toner particles is changed even by repeated copying by adding a specific amount of the small-sized inorganic fine particles and strontium titanate fine particles having a specific particle size to the conventional toner particles. It has become possible to provide a non-magnetic one-component developer that is difficult to resist, can maintain toner characteristics, and has excellent durability, in particular, charging stability.
[0009]
The small particle size inorganic fine particles contained in the developer of the present invention are inorganic fine particles having an average primary particle size of 1 to 70 nm, preferably 5 to 60 nm. Uniform desired toner fluidity can be obtained by containing the fine particles and uniformly coating the toner particles. If the average primary particle size is less than 1 nm, the toner charging stability due to long-term use and the toner charging stability against environmental changes are insufficient, and if it exceeds 70 nm, the dispersibility of the inorganic fine particles in the toner particles is significantly reduced. In addition, the fluidity and chargeability of the toner are not uniform, and a good copy image cannot be obtained.
[0010]
As materials used for the small particle size inorganic fine particles, various materials conventionally used as fluidizing agents can be used, for example, silica, alumina, titania (titanium dioxide), tin oxide, magnesium oxide. Zinc oxide or the like can be used alone or in admixture of two or more. Preferred small particle size inorganic fine particles are silica and titania).
[0011]
Further, the inorganic fine particles having a small particle diameter are contained in an amount of 0.3 to 3.0% by weight, preferably 0.5 to 2.5% by weight, more preferably 1.0 to 2.5% by weight based on the toner particles. It is desirable. If the amount is less than 0.3% by weight, desired fluidity cannot be imparted, durability is deteriorated, and white stripes and image unevenness are likely to occur in a copied image. On the other hand, if it exceeds 3.0% by weight, the inside of the machine is contaminated, the toner with poor charging is increased, fogging occurs in the copied image, and the cost is disadvantageous.
[0012]
In the present invention, the small particle size inorganic fine particles are preferably surface-treated with a hydrophobizing agent. This is to suppress changes in the toner charge amount due to the environmental stability of the toner, particularly the influence of humidity. The degree of hydrophobicity is 30 to 80%, preferably 40 to 80%. This is because when the degree of hydrophobicity is lower than 30%, the environmental resistance is liable to deteriorate, and when it exceeds 80%, it is difficult to obtain stably in production.
[0013]
As the hydrophobizing agent, conventionally used hydrophobizing agents such as silane coupling agents, titanate coupling agents, silicone oils, silicone varnishes and the like can be used, preferably silane coupling agents, silicone type Oil, more preferably a silane coupling agent is used. Examples of the silane coupling agent include trimethylsilane, trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, benzyldimethylchlorosilane, methyltrimethoxysilane, methyltriethoxysilane, isobutyltrimethoxysilane, n-hexyltrimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, trimethylmethoxysilane, hydroxypropyltrimethoxysilane, phenyltrimethoxysilane, n-hexadecyltrimethoxysilane, n-octyltrimethoxysilane, n-octadecyltri Methoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxy Runs can be used.
[0014]
As the silicone oil, for example, dimethylpolysiloxane, methylhydrogenpolysiloxane, methylphenylpolysiloxane and the like can be used.
The hydrophobizing agent may be used in an amount used to achieve the above degree of hydrophobization, and may be treated by a conventional method.
[0015]
In the present invention, the inorganic fine particles may be further surface treated with a fluorine-based silane coupling agent or fluorine-based silicon oil. This is because the toner is negatively charged and is effective in improving the negatively charged property of the toner and preventing image fogging. Normally, the chargeability of the toner is controlled by incorporating a charge control agent in the toner particles. However, in the one-component development system according to the present invention, the developer carrier and the developer regulating member Since the toner is charged by frictional charging when the toner passes through the gap between the press contact portions, the chargeability of the toner particle surface is important for the chargeability of the toner. For this reason, when chargeability control is performed, it is more effective to adjust the chargeability of the external additive of the toner than to adjust the content of the charge control agent.
[0016]
As the fluorine-based silane coupling agent, for example, those shown below can be used alone or in combination, but are not limited thereto.
・ CF_Three(CH₂)₂SiCl_Three
・ CF_Three(CF₂)_FiveSiCl_Three
・ CF_Three(CF₂)_Five(CH₂)₂SiCl_Three
・ CF_Three(CF₂)₇(CH₂)₂SiCl_Three
・ CF_Three(CF₂)₇CH₂CH₂Si (OCH_Three)_Three
・ CF_Three(CF₂)₇(CH₂)₂Si (CH_Three) Cl₂
・ CF_Three(CH₂)₂Si (OCH_Three)_Three
・ CF_Three(CH₂)₂Si (CH_Three) (OCH_Three)₂
・ CF_Three(CF₂)_Three(CH₂)₂Si (OCH_Three)_Three
・ CF_Three(CF₂)_Five(CH₂)₂Si (OCH_Three)_Three
・ CF_Three(CF₂)₆CONH (CH₂)₂Si (OC₂H_Five)_Three
・ CF_Three(CF₂)₆COO (CH₂)₂Si (OCH_Three)_Three
・ CF_Three(CF₂)₇(CH₂)₂Si (OCH_Three)_Three
・ CF_Three(CF₂)₇(CH₂)₂Si (CH_Three) (OCH_Three)₂
・ CF_Three(CF₂)₇NH (CH₂)_ThreeSi (OC₂H_Five)_Three
・ CF_Three(CF₂)₈(CH₂)₂Si (OCH_Three)_Three
[0017]
The fluorine-based silane coupling agent is used in an amount of 1 to 20 parts by weight, preferably 2 to 15 parts by weight, based on 100 parts by weight of the inorganic fine particles.
[0018]
In order to surface-treat inorganic fine particles using the surface treatment agent (fluorine coupling agent or fluorine-based silicone oil, hydrophobizing agent), for example, the surface treatment agent is diluted with a solvent, and the diluent is added to the inorganic fine particles. After the mixture is heated and dried, the dry method of crushing, the inorganic fine particles are dispersed in an aqueous system to form a slurry, and the surface treatment agent is added and mixed, and this is heated and dried. It can be carried out by a wet method of crushing. In particular, from the viewpoint of uniformity of the surface treatment of the hydrophobizing agent with respect to the inorganic fine particles and the prevention of aggregation of the inorganic fine particles, the hydrophobization treatment is performed in an aqueous system, and then a dry method is used with a fluorinated coupling agent or a fluorinated silicone oil. A surface treatment is preferred.
[0019]
In the present invention, a mixture of two or more kinds of inorganic fine particles having different average primary particle sizes within the above range may be used as the small particle size inorganic fine particles. Hereinafter, a case where the inorganic fine particles having the smaller particle diameter are used as the first inorganic fine particles, the inorganic fine particles having the larger particle diameter are used as the second inorganic fine particles, and these two kinds of inorganic fine particles are used as the above-mentioned small particle inorganic particles are described.
[0020]
In the present invention, when a mixture of the first inorganic fine particles and the second inorganic fine particles is used as the small particle inorganic fine particles, it is preferable that any one of the inorganic fine particles is made of silica, and more preferably, the other inorganic fine particle is titania. It is made up of. Thus, by using two types of inorganic fine particles of silica and titania, the environmental resistance and the chargeability are improved, and these effects become remarkable particularly when a full-color developer is prepared.
[0021]
The first inorganic fine particles desirably have an average primary particle size of 1 to 40 nm, preferably 5 to 35 nm, and more preferably 5 to 30 nm. By containing inorganic fine particles having such a particle diameter, desired toner fluidity can be obtained more easily. If the average primary particle size is less than 1 nm, the toner charging stability due to long-term use and the toner charging stability against environmental changes are insufficient, and if it exceeds 40 nm, the effect of improving fluidity becomes difficult to obtain.
[0022]
The second inorganic fine particles preferably have an average primary particle size of 40 to 70 nm, preferably 40 to 60 nm, and 10 nm or more larger than the average primary particle size of the first inorganic fine particles. The decrease in toner fluidity due to repeated copying, which has been a problem in the past, is considered to be caused by the fact that inorganic fine particles having a small particle size such as the first inorganic fine particles are embedded in the toner particles. By containing, the embedding can be relaxed and desired fluidity can be ensured. If the average primary particle size is less than 40 nm, the embedding mitigation effect of the first inorganic fine particles in the toner particles tends to be remarkably reduced, and if it exceeds 70 nm, the dispersibility of the inorganic fine particles in the toner particles is remarkably reduced. Property and chargeability become non-uniform, and a good copy image cannot be obtained.
[0023]
The content of the first inorganic fine particles and the second inorganic fine particles is set so that the total content thereof becomes the content of the above-mentioned small particle size inorganic fine particles. 0.1 to 2.0% by weight, preferably 0.3 to 1.5% by weight, and the second inorganic fine particles are 0.1 to 2.5% by weight, preferably 0.3 to 2%, based on the toner particles. It is desirable that it is contained at a ratio of 0.0% by weight. If the content of the first inorganic fine particles is less than 0.1% by weight, the desired fluidity is difficult to be imparted, and white streaks are likely to occur in the copy image. Defective toner increases and fog is likely to occur in the copied image, and also disadvantageous in terms of cost. If the content of the second inorganic fine particles is less than 0.1% by weight, the embedding mitigation effect of the first inorganic fine particles becomes difficult to obtain. If the content is more than 2.5% by weight, in-machine contamination occurs or toner with poor charge increases. As a result, the copied image is likely to be fogged, and the cost is also disadvantageous.
[0024]
The strontium titanate fine particles contained in the developer of the present invention have an average primary particle size of 100 to 500 nm, preferably 150 to 400 nm. By including the fine particles, toner component fixation at the restriction portion (contact portion between the developer restriction member and the developer carrier) is removed by the polishing action of the fine particles (hereinafter referred to as a refresh effect). The toner chargeability and non-uniformity of the formed toner thin layer due to the accumulation of toner particles and the like on the developer carrier, which has been a problem in the past, can be avoided, and a good copy image can be provided. Further, since the fine particles are weakly positively charged, the fine particles are effectively attached to negatively charged toner particles, and particularly have a great effect on toner charging stability. Further, the external addition of the fine particles allows the photoreceptor to be appropriately polished, and an effect as a cleaning improver can be expected.
[0025]
In addition, since the strontium titanate fine particles have a relatively large particle size, the probability of contact between toner particles is reduced, and external stresses such as regulation by the developer regulating member during development and agitation in the developing device diffuse. Therefore, the toner particle surface is not easily affected by external stress. Furthermore, the strontium titanate fine particles have a function of enhancing the embedding relaxation function of the small particle size inorganic fine particles.
[0026]
If the average primary particle size is less than 100 nm, the refreshing effect of the developer regulating member cannot be expected, and fogging due to an increase in the reverse charge component tends to occur with respect to chargeability. Further, the contact probability between the toner particles is increased, and external stress directly affects the surface of the toner particles, so that the above function cannot be exhibited. On the other hand, if it exceeds 500 nm, it becomes difficult to adhere to the toner particles, and most of the strontium titanate fine particles are detached and clogged with the developer regulating member, which causes problems such as poor charging, thin layer formation failure and in-machine contamination.
[0027]
In the present invention, the strontium titanate fine particles may be surface-treated with the above hydrophobizing agent in the same manner as the small particle size inorganic fine particles from the viewpoint of aggregation and dispersibility.
[0028]
The content of the strontium titanate fine particles is desirably 0.3 to 3.0% by weight, preferably 0.4 to 2.0% by weight, based on the toner particles. If the amount is less than 0.3% by weight, the effect of refreshing the developer carrier cannot be obtained, and the function of embedding the inorganic fine particles in the toner particles cannot be exhibited, resulting in a problem in fluidity. On the other hand, when the amount is more than 3.0% by weight, problems such as charging failure, thin layer formation failure and in-machine contamination occur due to clogging of the developer regulating member by the strontium titanate fine particles detached from the toner particles.
[0029]
The above small particle size inorganic fine particles and strontium titanate fine particles are externally added to negatively charged toner particles obtained by a known method. The negatively charged toner particles used in the present invention contain at least a binder resin and a colorant.
[0030]
As the binder resin used in the present invention, a resin capable of making the obtained toner particles negatively charged is used. In this case, a resin that can be controlled to be negatively charged by internally adding a charge control agent described later may be used. In order to improve the dispersibility of the colorant in the binder resin, 1.0 to 30.0 KOH mg / g, preferably 1.0 to 25.0 KOH mg / g, more preferably 2.0 to 20.0 KOH mg. It is desirable to use a resin having an acid value of / g. This is because when the acid value is less than 1.0 KOH mg / g, the effect of improving dispersibility is small, and when it is greater than 30.0 KOH mg / g, the change in charge amount due to environmental fluctuations becomes large.
[0031]
If it is such binder resin, the kind of resin will not be limited, for example, styrene resin, acrylic resin, styrene-acrylic resin, polyamide resin, polyester resin, polyurethane resin, epoxy resin, and other known ones These resins can be used alone or in combination, and a preferred one can be appropriately selected and used depending on the application. For example, when preparing a negatively charged toner without using a charge control agent, a polyester resin is used. When preparing a negatively charged toner using a negative charge control agent, a polyester resin or styrene-acrylic is used. It is preferable to use a polyester-based resin, a polyester-based resin when preparing a full-color toner, and a polyester-based resin and a styrene-acrylic resin when preparing a black toner.
[0032]
In the present invention, a preferred polyester resin uses a bisphenol A alkylene oxide adduct as a main component as an alcohol component, and a polycondensation reaction using a phthalic dicarboxylic acid or a phthalic dicarboxylic acid and an aliphatic dicarboxylic acid as an acid component. It was synthesized by.
[0033]
As the bisphenol A alkylene oxide adduct, bisphenol A propylene oxide adduct and bisphenol A ethylene oxide adduct are suitable, and it is preferable to use a mixture of these.
[0034]
Moreover, you may use the following diol and polyhydric alcohol a little with a bisphenol A alkylene oxide adduct as an alcohol component. Examples of such alcohol components include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, diols such as neopentyl glycol, sorbitol, 1 , 2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, 2- Examples include methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene and the like.
[0035]
As the phthalic acid-based dicarboxylic acids, phthalic acid-based dicarboxylic acids such as terephthalic acid and isophthalic acid, their acid anhydrides or their lower alkyl esters can be used.
[0036]
Examples of aliphatic dicarboxylic acids that can be used with phthalic acid-based dicarboxylic acids include fumaric acid, maleic acid, succinic acid, aliphatic dicarboxylic acids such as alkyl having 4 to 18 carbon atoms or alkenyl succinic acid, acid anhydrides thereof, or the like. Examples thereof include lower alkyl esters.
[0037]
Further, a small amount of polyvalent carboxylic acid such as trimellitic acid may be used as long as the translucency of the toner is not impaired in order to adjust the acid value of the resin. Examples of such a polyvalent carboxylic acid component include 1,2,4-benzenetricarboxylic acid (trimellitic acid), 1,2,5-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 2,4-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4 -Cyclohexanetricarboxylic acid, tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, their anhydrides, lower alkyl esters and the like.
[0038]
When the negatively charged toner particles of the present invention are used as a full-color toner, a binder resin preferable for the glass transition point is 55 to 75 ° C, preferably 58 to 70 ° C, and the softening point is 95 to 120 ° C, preferably 100 to 118. ° C, the number average molecular weight is 2500 to 6000, preferably 3000 to 5500, and the weight average molecular weight / number average molecular weight is 2 to 8, preferably 3 to 7. When the glass transition point is lowered, the heat resistance of the toner is lowered, and when it is raised, the translucency and the color mixing property are lowered. When the softening point is lowered, high temperature offset is likely to occur at the time of fixing, and when it is increased, the fixing strength is lowered. When the number average molecular weight is small, the toner is easily peeled off when the image is folded, and when the number average molecular weight is large, the fixing strength is lowered. Further, when the weight average molecular weight / number average molecular weight is small, high temperature offset is likely to occur, and when it is large, the translucency is lowered.
[0039]
As the colorant, various known colorants such as cyan, magenta, yellow, and black can be used, and the same amount as before can be applied. Usually, the colorant is added in an amount of about 1 to 15 parts by weight with respect to 100 parts by weight of the binder resin.
[0040]
In addition to the colorant, desired additives such as a charge control agent and an offset preventive agent may be added to the negatively charged toner particles of the present invention.
[0041]
As the charge control agent, a zinc salicylate complex or the like and other known negative charge control agents can be used, and the type may be selected according to the purpose of use. For full-color copying, it is preferable to use a colorless, white or light yellow charge control agent. There is no particular limitation for black copying. The amount of the charge control agent used may be appropriately set according to the purpose of use, but is usually 0.1 to 10 parts by weight, preferably 0.5 to 5.0 parts by weight with respect to 100 parts by weight of the binder resin. Used in the range of
[0042]
Further, it is not particularly limited as an offset preventing agent, for example, polyethylene wax, oxidized polyethylene wax, polypropylene wax, oxidized polypropylene wax, carnauba wax, sazol wax, rice wax, candelilla wax, jojoba oil wax, Beeswax wax can be used. This not only improves the anti-offset property, but also can reduce the problem of toner sticking to the developer regulating member, developer carrier, etc. in the non-magnetic one-component developing device. In particular, it is preferable to use a wax having an acid value of 0.5 to 30 KOH mg / g from the viewpoint of dispersibility with respect to the binder resin having the acid value. The amount of such wax added is 0.5 to 5 parts by weight, preferably 1 to 4 parts by weight, based on 100 parts by weight of the binder resin. This is because if the amount added is less than 0.5 parts by weight, the effect of the addition is insufficient, and if it exceeds 5 parts by weight, the translucency and color reproducibility are lowered.
[0043]
The toner particles according to the present invention use the above-mentioned binder resin, colorant and other desired additives, kneading / pulverization method, suspension polymerization method, emulsion polymerization method, emulsion dispersion granulation method, encapsulation method, etc. It can manufacture by the well-known method of these. Among these production methods, production by a kneading and pulverization method is preferable from the viewpoint of production cost and production stability.
[0044]
The kneading and pulverization method includes a step of mixing resin components such as a resin and a colorant with a mixer such as a Henschel mixer, a step of melting and kneading the mixture, a step of coarsely pulverizing the kneaded product, and the coarsely pulverized particles. The toner particles are produced by a step of finely pulverizing the toner and a step of classifying the obtained finely pulverized particles. The toner particles of the present invention preferably have a volume average particle size of 4 to 10 μm, preferably 6 to 9 μm, from the viewpoint of high-definition image reproducibility. The volume average particle diameter of the toner particles is a value measured using a Coulter Multisizer (manufactured by Coulter Counter) with an aperture diameter of 100 μm.
[0045]
The obtained toner particles are mixed with the above-mentioned small particle size inorganic fine particles and strontium titanate fine particles using a mixer such as a Henschel mixer to prepare as a non-magnetic one-component developer.
[0046]
The non-magnetic one-component developer of the present invention thus obtained can be used as a developer for full color or black by appropriately selecting a colorant, a binder resin, a charge control agent, a wax and the like. Although it is possible, it is effective to use it as a full-color developer in the present invention. For this reason, the developer of the present invention can be used in any developing device as long as it is a developing device adopting a one-component developing system, but it is particularly preferable to use it in a full-color image forming apparatus. Hereinafter, an example of a full-color image forming apparatus will be described with reference to FIG.
[0047]
In FIG. 1, the full-color laser beam printer generally has a photoconductor drum 10 that is rotationally driven in the direction of arrow a, a laser scanning optical system 20, a full-color developing device 30, and an endless shape that is rotationally driven in the direction of arrow b. The intermediate transfer belt 40 and a paper feed unit 60 are included. Around the photosensitive drum 10, a cleaner 12 is further provided with a charging brush 11 for charging the surface of the photosensitive drum 10 to a predetermined potential, and a cleaner blade 12a for removing toner remaining on the photosensitive drum 10. is set up.
[0048]
The laser scanning optical system 20 is a well-known one incorporating a laser diode, a polygon mirror, and an fθ optical element, and its control unit prints for each of C (cyan), M (magenta), Y (yellow), and Bk (black). Data is transferred from the host computer. The laser scanning optical system 20 sequentially outputs print data for each color as a laser beam, and scans and exposes the photosensitive drum 10. Thereby, an electrostatic latent image for each color is sequentially formed on the photosensitive drum 10.
[0049]
The full-color developing device 30 is an integrated unit of four color developing devices 31C, 31M, 31Y, and 31Bk that contain a one-component developer made of non-magnetic toners of C, M, Y, and Bk. Can be rotated in the clockwise direction. Each developing device includes a developing sleeve (developer carrier) 32 and a toner regulating blade (developer regulating member) 34. The toner conveyed by the rotation of the developing sleeve 32 is charged by passing through a pressure contact portion (regulating portion) between the blade 34 and the developing sleeve 32.
[0050]
The intermediate transfer belt 40 is stretched endlessly by the support rollers 41 and 42 and the tension rollers 43 and 44 and is driven to rotate in the direction of arrow b in synchronization with the photosensitive drum 10. A projection (not shown) is provided on a side portion of the intermediate transfer belt 40, and the microswitch 45 detects the projection to control image forming processes such as exposure, development, and transfer. The intermediate transfer belt 40 is pressed by a rotatable primary transfer roller 46 and is in contact with the photosensitive drum 10. This contact portion is the primary transfer portion T.₁It is. The intermediate transfer belt 40 is in contact with a rotatable secondary transfer roller 47 at a portion supported by the support roller 42. This contact portion is the secondary transfer portion T.₂It is.
[0051]
Further, a cleaner 50 is installed in the space between the developing device 30 and the intermediate transfer belt 40. The cleaner 50 has a blade 51 for removing residual toner on the intermediate transfer belt 40. The blade 51 and the secondary transfer roller 47 can be brought into contact with and separated from the intermediate transfer belt 40.
[0052]
The paper feed unit 60 includes a paper feed tray 61 that can be opened to the front side of the image forming apparatus main body 1, a paper feed roller 62, and a timing roller 63. The recording sheet S is stacked on the paper feed tray 61, fed one sheet at a time to the right in the figure by the rotation of the paper feed roller 62, and synchronized with the image formed on the intermediate transfer belt 40 by the timing roller 63. To the secondary transfer section. The recording sheet horizontal conveyance path 65 includes an air suction belt 66 including the paper feeding unit, and a vertical conveyance path 71 including conveyance rollers 72, 73, and 74 is provided from the fixing device 70. The recording sheet S is discharged from the vertical conveyance path 71 to the upper surface of the image forming apparatus main body 1.
[0053]
Here, the printing operation of the full-color printer will be described.
When the printing operation is started, the photosensitive drum 10 and the intermediate transfer belt 40 are rotationally driven at the same peripheral speed, and the photosensitive drum 10 is charged to a predetermined potential by the charging brush 11.
[0054]
Subsequently, a cyan image is exposed by the laser scanning optical system 20, and an electrostatic latent image of the cyan image is formed on the photosensitive drum 10. The electrostatic latent image is immediately developed by the developing device 31C, and the toner image is transferred onto the intermediate transfer belt 40 at the primary transfer portion. Immediately after the completion of the primary transfer, the developing device 31M is switched to the developing portion D, and then magenta image exposure, development, and primary transfer are performed. Further, switching to the developing device 31Y, yellow image exposure, development, and primary transfer are performed. Further, switching to the developing device 31Bk, black image exposure, development, and primary transfer are performed, and the toner image is superimposed on the intermediate transfer belt 40 for each primary transfer.
[0055]
When the final primary transfer is completed, the recording sheet S is sent to the secondary transfer portion, and the full-color toner image formed on the intermediate transfer belt 40 is transferred onto the recording sheet S. When the secondary transfer is completed, the recording sheet S is conveyed to the belt-type contact heating and fixing device 70, and the full-color toner image is fixed on the recording sheet S and discharged onto the upper surface of the printer main body 1.
The invention is further illustrated by the following examples.
[0056]
【Example】
In this example, the production method of the polyester resins A to C used is shown below.
(Manufacture of polyester resin A (for color toner))
To a glass four-necked flask equipped with a thermometer, stirrer, flow-down condenser and nitrogen inlet tube, polyoxypropylene (2,2) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene ( 2,2) -2,2-bis (4-hydroxyphenyl) propane and terephthalic acid were charged in a molar ratio of 5: 5: 7.5. Further, after adding a polymerization initiator (dibutyltin oxide), these are reacted in a mantle heater with stirring at 220 ° C. in a nitrogen atmosphere to obtain a number average molecular weight (Mn) of 4800, a weight average molecular weight / number average molecular weight. 5. A polyester resin A having a softening point of 108 ° C., a glass transition point of 66 ° C., and an acid value (AV) of 4.2 KOH mg / g was obtained.
[0057]
(Manufacture of polyester resin B (for black toner))
To a glass four-necked flask equipped with a thermometer, stirrer, flow-down condenser and nitrogen inlet tube, polyoxypropylene (2,2) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene ( 2,2) -2,2-bis (4-hydroxyphenyl) propane, isododecenyl succinic anhydride, terephthalic acid and fumaric acid were charged at a weight ratio of 82: 77: 16: 32: 30. Furthermore, after adding a polymerization initiator (dibutyltin oxide), these were reacted in a mantle heater with stirring at 220 ° C. in a nitrogen atmosphere, a softening point of 110 ° C., a glass transition point of 60 ° C., an acid value of 17.5 KOHmg / g of polyester resin B was obtained.
[0058]
(Manufacture of polyester resin C (for black toner))
Styrene and 2-ethylhexyl acrylate were adjusted to a weight ratio of 17: 3.2 and placed in a dropping funnel together with digamyl peroxide as a polymerization initiator. On the other hand, polyoxypropylene (2,2) -2,2-bis (4-hydroxyphenyl) propane, polyoxy was added to a glass four-necked flask equipped with a thermometer, a stirrer, a downflow condenser and a nitrogen inlet tube. Ethylene (2,2) -2,2-bis (4-hydroxyphenyl) propane, isododecenyl succinic anhydride, terephthalic acid, 1,2,4-benzenetricarboxylic acid anhydride and acrylic acid in a weight ratio of 42:11:11 The mixture was adjusted to 1: 1: 8: 1 and charged together with a polymerization initiator (dibutyltin oxide). While stirring these at 135 ° C. in a mantle heater in a mantle heater, styrene and the like were added dropwise from a dropping funnel, and the temperature was raised and reacted at 230 ° C., and the softening point was 150 ° C., the glass transition point was 62 ° C. 24.5 KOHmg / g of polyester resin C was obtained.
[0059]
In addition, molecular weight calculated | required molecular weight by polystyrene conversion using gel permeation chromatography (807-IT type; JASCO Corporation make), using tetrahydrofuran as a carrier solvent.
[0060]
For the softening point, a flow tester (CFT-500; manufactured by Shimadzu Corporation) was used, a 1.0 mm × 1.0 mm die was used for 1.0 g of the sample, and the temperature increase rate was 3.0 ° C./min. The measurement was performed under a load of 30 kg, and the temperature at which the sample flowed out by half was defined as the softening point.
[0061]
The glass transition point was measured for 10 mg of a sample weighed using a differential scanning calorimeter (DSC-200; manufactured by Seiko Denshi Co., Ltd.), using alumina as a reference, The glass transition point was used.
[0062]
The acid value was expressed in mg of potassium hydroxide required to dissolve a weighed sample in an appropriate solvent and neutralize the acidic group using an indicator such as phenolphthalein.
[0063]
In the examples, the following inorganic fine particles were used as the inorganic fine particles.
Inorganic fine particles A (hydrophobic silica, hydrophobicity 55%, average primary particle size 7 nm, TS500; manufactured by Cabogil)
Inorganic fine particle B (hydrophobic silica, hydrophobicity 48%, average primary particle size 15 nm, R974; manufactured by Nippon Aerosil Co., Ltd.)
Inorganic fine particles C (hydrophobic silica, hydrophobicity 55%, average primary particle size 50 nm, R809; manufactured by Nippon Aerosil Co., Ltd.)
[0064]
Inorganic fine particles D (hydrophobic titanium dioxide, hydrophobized degree 55%, rutile titanium dioxide (MT-150W; manufactured by Teica) having an average primary particle size of 15 nm is surface-treated with n-hexyltrimethoxysilane)
Inorganic fine particles E (hydrophobic titanium dioxide, anatase-type titanium dioxide having a hydrophobization degree of 60% and an average primary particle size of 20 nm and surface-treated with n-hexyltrimethoxysilane)
Inorganic fine particles F (hydrophobic titanium dioxide, hydrophobized degree 57%, anatase type titanium dioxide having an average primary particle size of 50 nm and surface-treated with n-hexyltrimethoxysilane)
Inorganic fine particles G (hydrophobic titanium dioxide, hydrophobization degree 50%, inorganic fine particles F are further added with a fluorinated silane coupling agent (CF_Three(CH₂)₂Si (OCH_Three)_ThreeSurface-treated with
[0065]
Inorganic fine particles a (strontium titanate, average primary particle size 250 nm)
Inorganic fine particles b (strontium titanate, average primary particle size 1000 nm)
Inorganic fine particles c (hydrophobic titanium dioxide, hydrophobized degree 49%, rutile type titanium dioxide having an average primary particle size of 250 nm (KR-380; manufactured by Titanium Industry Co., Ltd.) surface-treated with silicon oil)
[0066]
The degree of hydrophobicity was obtained by adding 50 ml of pure water to a 200 ml beaker, adding 0.2 g sample, adding methanol dehydrated with anhydrous sodium sulfate from the burette while stirring the beaker, and almost the sample was seen on the liquid surface. From the point of disappearance, the following formula:
Hydrophobicity = [methanol used / (50 + methanol used)] × 100
Calculated by
[0067]
Moreover, the manufacturing method of the melt blend polypropylene wax used as a wax in a present Example is shown below.
(Manufacture of melt blended polypropylene wax)
A non-oxidized polypropylene wax having an acid value of 0 KOH mg / g (Biscol 550P; manufactured by Sanyo Chemical Industries) and an oxidized polypropylene wax having an acid value of 52 KOH mg / g (Yumex 1010; manufactured by Sanyo Chemical Industries) were mixed at a weight ratio of 92: 8. After melt-kneading, the mixture was cooled and pulverized to obtain a melt blended polypropylene wax having an acid value of 4.0 KOH mg / g, a melt viscosity of 205 cps at 160 ° C., and a softening point of 150 ° C.
[0068]
Example 1
Polyester resin A and cyan pigment (CI Pigment Blue 15-3) were charged into a pressure kneader at a weight ratio of 7: 3 and kneaded. The obtained kneaded product was cooled and then pulverized by a feather mill to obtain a pigment master batch.
[0069]
93 parts by weight of polyester resin A, 10 parts by weight of the above-mentioned pigment master batch, 2 parts by weight of polypropylene wax (Biscol TS200; manufactured by Sanyo Chemical Industries; acid value 3.5 KOHmg / g) and zinc salicylate complex (E84; manufactured by Orient Chemical Industries) ) 1.5 parts by weight were sufficiently mixed with a ball mill, the mixture was melt-kneaded with a twin-screw extrusion kneader (PCM-30; manufactured by Ikegai Iron Works Co., Ltd.), cooled, and then coarsely pulverized with a feather mill. The coarsely pulverized product was finely pulverized by a jet mill and classified into fine powders to obtain toner particles having a volume average particle size of 8.0 μm.
[0070]
To 100 parts by weight of the obtained toner particles, 0.5 part by weight of inorganic fine particles A, 1.0 part by weight of inorganic fine particles F and 1.0 part by weight of inorganic fine particles a were added and mixed by a ball mill to obtain a developer.
[0071]
  Examples 2-7 and Comparative Examples 1-6
  A developer was obtained in the same manner as in Example 1 except that the inorganic fine particles shown in Table 1 or 2 were used in the indicated addition amount.
[0072]
  Example 8
  A developer was obtained in the same manner as in Example 1 except that toner particles having a volume average particle diameter of 6.1 μm were prepared and used.
[0073]
  Example 9
  Polyester resin B 40 parts by weight, polyester resin C 60 parts by weight, polyethylene wax (800P; manufactured by Mitsui Petrochemical Co., Ltd .; melt viscosity at 160 ° C. 5400 cps; softening point 140 ° C.), melt blended polypropylene wax 3 parts by weight, 8 parts by weight of acidic carbon black (Mogal L; manufactured by Cabot; pH 2.5; average primary particle size: 24 nm) and 2.5 parts by weight of zinc salicylate complex (E84; manufactured by Orient Chemical Co., Ltd.) were sufficiently mixed with a Henschel mixer. The mixture was melt-kneaded with a twin-screw extrusion kneader (PCM-30; manufactured by Ikekai Tekko Co., Ltd.), cooled, and then coarsely pulverized with a hammer mill. The coarsely pulverized product was finely pulverized with a jet pulverizer and classified into fine powders to obtain toner particles having a volume average particle size of 8.2 μm.
[0074]
To 100 parts by weight of the obtained toner particles, 0.5 parts by weight of inorganic fine particles A, 0.5 parts by weight of inorganic fine particles G and 1.0 parts by weight of inorganic fine particles a were added and mixed by a ball mill to obtain a developer.
[0075]
  Example 10
  Examples other than using the inorganic fine particles shown in Table 1 in the indicated addition amount9In the same manner as above, a developer was obtained.
[0076]
Evaluation
The developer thus obtained is mounted on a modified electrophotographic printer (SP1000; manufactured by Minolta Co.) equipped with a non-magnetic one-component developing device in which the pressure contact force of the regulating blade is variably modified. At a temperature of 45%, a character pattern having a B / W ratio of 5% was set to be drawn, and “white stripes” and “charge amount” described in detail below were evaluated. These evaluations were made on the initial (after 10 copies) and the copied images after 3000 copies.
[0077]
(White stripe)
Copy an A4 halftone image, observe the occurrence of white streaks on the copied image, and observe the occurrence of streaks on the thin layer of toner formed on the developing sleeve, according to the following ranking: evaluated.
○: No streaks occurred in the toner thin layer formed on the sleeve, and no white streaks occurred on the image;
Δ: Although slight unevenness was generated in the toner thin layer, no white streak was generated on the image, and there was no problem in practical use;
X: Straight stripes occurred in the toner thin layer, and white stripes occurred on the image.
[0078]
(Charge amount)
As described above, after evaluating white stripes at the initial stage (after copying 10 sheets) and after copying 3000 sheets, one sheet is passed in white development (white paper mode), and the charge amount by the toner suction method on the sleeve Measurements were made. The charge amount stability is excellent when the absolute value of the charge amount difference between the initial stage and after copying 3000 sheets is 5 μC / g or less.
[0079]
The above evaluation results are shown in Table 1 and Table 2 below together with the processing conditions in the above Examples and Comparative Examples.
[0080]
[Table 1]

[0081]
[Table 2]

[0082]
From these results, it has been clarified that the developer of the present invention does not generate white streaks in the copied image and has excellent chargeability. It can be seen that the developer of the present invention is excellent in durability and fluidity.
In Comparative Example 1, streaks began to appear in the toner thin layer from about 1500 sheets, and the toner became so severe that the toner spilled at the time of 2000 sheets. Therefore, measurement of the toner charge amount after copying 3000 sheets was stopped. In Comparative Example 2, a decrease in charge amount was recognized after copying 3000 sheets, and no sleeve refresh effect was observed. In addition, a lump of white powder adhered to the regulation blade corresponding to the portion where the streak occurred. In Comparative Example 3, since the toner thin layer was not formed on the sleeve from the beginning, only the white streak evaluation of the initial copy image was performed, and the subsequent copying was stopped. In Comparative Example 4, there were no problems such as white streaks, but the fluidity of the toner was too high, so the toner was slipped off at the restricting portion, and the rising of the charge of the toner was poor, and the initial charge amount was low. Greatly increased the charge amount. In Comparative Examples 5 and 6, there was a large change in charge amount at the initial stage and after copying 3000 sheets, and no sleeve refresh effect was observed.
[0083]
【The invention's effect】
According to the present invention, it is possible to provide a non-magnetic one-component developer excellent in fluidity, chargeability and durability, in which white lines are not generated in a copied image even by repeated copying.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a full-color image forming apparatus.
[Explanation of symbols]
10: photosensitive drum, 11: charging brush, 12: cleaner, 20: laser scanning optical system, 30: full-color developing device, 32: developer carrier (sleeve), 33: support shaft, 34: developer regulating member ( Blade), 40: intermediate transfer belt, 41: support roller, 42: support roller, 43: tension roller, 44: tension roller, 46: primary transfer roller, 47: secondary transfer roller, 60: paper feeding unit, 61 : Paper feed tray, 62: paper feed roller, 63: timing roller, 66: air suction belt, 70: fixing device, 71: vertical transport path.

Claims (3)

Non-magnetic one comprising negatively charged toner particles containing at least a binder resin and a colorant, small-sized inorganic fine particles having an average primary particle size of 1 to 70 nm, and strontium titanate fine particles having an average primary particle size of 100 to 500 nm. A component developer, the content of small particle size inorganic fine particles is 0.3 to 3.0% by weight with respect to the toner particles, and the content of strontium titanate fine particles is 0.3 to 3.0% with respect to the toner particles. 3.0% by weight, the small particle size inorganic fine particles are composed of two types of silica and titania, and the average primary particle size of the small particle size fine particles (referred to as “first inorganic fine particles”) of either silica or titania. but from 1 to 40 nm, an average primary particle size of the other small diameter particles (referred to as "second inorganic fine particles") and is 40 to 70 nm (average primary particle diameter, a scanning electron microscope (J M-840A; sample was observed by Nippon Denshi), which is the average of the major axis of the particles), within the range of content of the small-diameter inorganic fine particles, the content of the first inorganic fine particles to the toner particles A non-magnetic one-component developer, wherein the content of the second inorganic fine particles is 0.1 to 2.0% by weight and the content of the second inorganic fine particles is 0.1 to 2.5% by weight based on the toner particles.   2. The nonmagnetic one-component developer according to claim 1, wherein the content of the small particle size inorganic fine particles is 0.5 to 2.5% by weight based on the toner particles.   2. The nonmagnetic one-component developer according to claim 1, wherein the average primary particle size of the small particle size inorganic fine particles is 5 to 60 nm.

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