JP4074821B2 - Toner for developing electrostatic latent image and image forming method using the same - Google Patents

Description

【００５１】
【表２】

【００５２】
[実施例８〜１８および比較例３〜８]
表３に示すように、粒状酸化チタンの平均粒径および針状導電性粒子の大きさ（長軸および短軸）をそれぞれ変えたほかは、実施例１と同様にトナーを作成し、評価した。得られた結果を表４に示す。
【００５３】
【表３】

【００５４】
【表４】

【００５５】
【発明の効果】
本発明の静電潜像現像用トナーおよびそれを用いた画像形成方法によれば、チタネート系化合物で表面処理された平均粒径が０．０１〜０．５０μｍ未満の粒状酸化チタンと、長軸が０．２〜２．０μｍ、短軸が０．０１〜０．１μｍの針状導電性粒子と、をそれぞれトナー粒子に外添処理することにより、優れた研磨力を発揮して、チャージアップを防止するとともに、像流れの画像欠陥を生じることが著しく少なくなった。
また、特定の粒状酸化チタンおよび針状導電性粒子を添加しているため、耐久性、安定性に優れた帯電特性を付与することができ、いずれの温度、湿度下においても高画質の画像が安定して得られるようになった。
【００５６】
【図面の簡単な説明】
【図１】 本発明の静電潜像現像用トナーが適用される画像形成装置の断面図である。
【図２】 チタネート系化合物で表面処理された粒状酸化チタン／針状導電性粒子の添加割合と、帯電特性との関係を説明するために供する図である。
【図３】 チタネート系化合物で表面処理された粒状酸化チタン／針状導電性粒子の添加割合と、画像濃度との関係を説明するために供する図である。
【図４】 チタネート系化合物で表面処理された粒状酸化チタン／針状導電性粒子の添加割合と、カブリ性との関係を説明するために供する図である。
【図５】 チタネート系化合物で表面処理された粒状酸化チタン／針状導電性粒子の添加割合と、像流れ性との関係を説明するために供する図である。
【００５７】
【符号の説明】
１：画像形成装置
２：ポリゴンミラー
５：光学電送機構
７：上部扉
９：感光体
１０：現像器
３１：トナーコンテナ
３２：現像ローラ
３３：供給ローラ
３９：トナーセンサ
４７：表示部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a toner for developing an electrostatic latent image containing external additive particles and an image forming method using the same, and more specifically, static toner containing specific external additive particles having a good balance of charging characteristics and fluidity. The present invention relates to an electrostatic latent image developing toner and an image forming method using the same.
[0002]
[Prior art]
In electrophotography, the toner used to make an electrostatic latent image a visible image is generally premixed with thermoplastic resin (binder resin), waxes, charge control agent, magnetic powder, and other additives. After that, the toner is manufactured as a toner having a desired particle diameter through each of the manufacturing steps of the melt kneading step, the pulverizing step, and the classification step. As shown in FIG. 1, the toner manufactured in this way accumulates a certain amount of electric charge by frictional charging, and then develops the electrostatic latent image on the photoconductor to obtain a desired visible image. It is provided.
Here, the charge accumulated in the toner due to frictional charging needs to be either positive or negative depending on the type of the photoreceptor on which the electrostatic latent image is formed. Further, the charge amount of the toner by frictional charging needs to be a sufficient amount to make the electrostatic latent image visible more accurately. Further, in recent years, as a photoconductive photoreceptor for forming an electrostatic latent image, in place of a selenium photoreceptor or an organic photoconductive photoreceptor, it has pollution-free and high sensitivity, and has a Vickers strength of 1, Amorphous silicon photoconductors (hereinafter referred to as a-Si photoconductors) are frequently used because they have characteristics such as extremely hard values of 500 to 2,000. Therefore, in order to develop the electrostatic latent image formed on the a-Si photoreceptor, it is desired to use a toner having excellent chargeability and durability. For this reason, not only a charge control agent and a conductive substance are added to the binder resin, but also inorganic oxides (fine powder) such as silica, aluminum oxide, titanium oxide, and zinc oxide are added to the toner (toner particles). Externally added, the polarity of the charge and the charge amount are controlled, and the durability and polishing properties are also controlled.
However, these inorganic oxides are very hydrophilic because of the hydroxyl groups present on the surface. As a result, when added to toner, the fluidity and charge rise characteristics of the toner change due to the influence of humidity, and printing In some cases, there were adverse effects such as durability and reduced image density.
[0003]
Therefore, in order to prevent the influence of such environmental conditions as humidity, the inorganic oxide is treated with a hydrophobizing agent or a polar group is introduced. For example, in order to introduce a polar group, a technique using titanium oxide treated with a silane coupling agent such as an aminosilane compound has been proposed (Patent Document 1 and Patent Document 2).
Furthermore, an electrostatic latent image developer is proposed in which abrasive fine particles such as alumina and zirconia are fixed to the surface of the toner particles, and the ratio between the particle size of the toner particles and the particle size of the abrasive fine particles is controlled (patent). Reference 3). According to this method, it is possible to obtain an excellent polishing effect on the surface of the photosensitive member, it is not necessary to incorporate a large system such as a cleaning brush, and the apparatus can be miniaturized, and against image flow, image density, fog, etc. effective.
[0004]
[Patent Document 1]
JP 52-135739 A (Claims)
[Patent Document 2]
Japanese Patent Laid-Open No. 10-3177 (Claims)
[Patent Document 3]
JP-A-5-181306 (Claims)
[0005]
However, this conventional technique has the following problems.
{Circle around (1)} In the prior art disclosed in Patent Document 1 and Patent Document 2, the polishing ability for the surface of the photoconductor is insufficient, which may cause problems such as drum filming.
(2) Although the conventional technique disclosed in Patent Document 3 can exhibit an appropriate polishing ability on the surface of the photoreceptor, the charging characteristics are unstable under both high temperature and high humidity conditions and low temperature and low humidity conditions. there were.
[0006]
[Problems to be solved by the invention]
Therefore, as a result of diligently examining conventional problems, by adding a combination of specific granular titanium oxide and specific acicular conductive particles as an external additive, it has an excellent balance of charging characteristics and fluidity. The present inventors have found that a toner for developing an electrostatic latent image can be obtained and completed the present invention.
That is, the object of the present invention is to provide a stable charge characteristic with a uniform charge amount distribution, without reducing the triboelectric charge amount, and without charging up, and a balance of fluidity, environmental dependency, durability characteristic, etc. It is an object of the present invention to provide an electrostatic latent image developing toner excellent in the above-mentioned.
[0007]
[Means for Solving the Problems]
  According to the present invention,Toner particles, granular titanium oxide having an average particle size of 0.01 to less than 0.50 μm surface-treated with a titanate compound, a major axis of 0.2 to 2.0 μm, and a minor axis of 0.01 to 0.1 μm of acicular conductive titanium oxide is externally added, and the addition ratio of granular titanium oxide and acicular conductive titanium oxide is within the range of 10:90 to 90:10 by weight ratio. Value ofAn electrostatic latent image developing toner is provided, which can solve the above-mentioned problems.
  With this configuration, the toner charge amount distribution is uniform, exhibits stable charging characteristics without lowering the triboelectric charge amount, and without charging up, and has fluidity, environmental dependence, and durability characteristics. An excellent electrostatic latent image developing toner can be obtained.
[0008]
  Further, in constituting the electrostatic latent image developing toner of the present invention, acicular conductive titanium oxide contains SnO.₂/ Sb-based conductive particles, that is, on the surface of acicular titanium oxide,Tin oxide (SnO ₂ ) And antimony (Sb) doped conductive particlesIt is preferable that
  With this configuration, it is possible to obtain an electrostatic latent image developing toner that is excellent not only in conductivity but also in transparency. SnO₂Since the / Sb-based conductive particles are excellent in mechanical strength, there is also an advantage that the needle-like shape can be maintained for a long time.
[0009]
Further, in constituting the electrostatic latent image developing toner of the present invention, the total addition amount of the granular titanium oxide and the acicular conductive particles is 0.5 to 7.0 parts by weight with respect to 100 parts by weight of the toner particles. A value within the range is preferable.
With this configuration, it is possible to obtain a toner for developing an electrostatic latent image that has a more uniform toner charge amount distribution, exhibits stable charging characteristics without lowering the triboelectric charge amount, and without charging up. Can do.
[0011]
In constructing the electrostatic latent image developing toner of the present invention, the volume resistivity of the acicular conductive particles is set to 1 × 10.^-1~ 1x10^FourA value within the range of Ω · cm is preferable.
With this configuration, it is possible to obtain a toner for developing an electrostatic latent image that has a more uniform charge amount distribution of the toner and exhibits stable charging characteristics without being charged up.
[0012]
In constituting the electrostatic latent image developing toner of the present invention, the granular titanium oxide is preferably anatase-type titanium oxide and rutile-type titanium oxide, or titanium oxide having one of the crystal structures.
With this configuration, it is possible to obtain a toner for developing an electrostatic latent image that has a more uniform charge amount distribution of the toner and exhibits stable charging characteristics without being charged up.
[0013]
  According to another aspect of the present invention, there is provided an image forming method using toner for developing an electrostatic latent image composed of toner particles and externally added particles. In contrast, granular titanium oxide having an average particle size of 0.01 to less than 0.50 μm and surface-treated with a titanate compound, a major axis of 0.2 to 2.0 μm, and a minor axis of 0.01 to 0.1 μm ofAcicular conductive titanium oxideWhen,And the addition ratio of granular titanium oxide and acicular conductive titanium oxide is a value within the range of 10:90 to 90:10 by weight ratio.And an electrostatic latent image developing toner.
  By carrying out in this way, an image having a uniform toner charge amount distribution and excellent image characteristics can be obtained.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the toner for developing an electrostatic latent image of the present invention and an image forming method using the same will be described in detail.
[0015]
[First embodiment]
  The first embodiment isToner particles, granular titanium oxide having an average particle size of 0.01 to less than 0.50 μm surface-treated with a titanate compound, a major axis of 0.2 to 2.0 μm, and a minor axis of 0.01 to 0.1 μm of acicular conductive titanium oxide is externally added, and the addition ratio of granular titanium oxide and acicular conductive titanium oxide is within the range of 10:90 to 90:10 by weight ratio. Value ofThis is an electrostatic latent image developing toner.
[0016]
1. Toner particles
In the toner used in the first embodiment, an inorganic oxide is externally added to toner particles composed of, for example, a binder resin, waxes, a charge control agent, and magnetic powder according to actual conditions. Preferably it is.
[0017]
(1) Binder resin
The type of the binder resin used for the toner used in the first embodiment is not particularly limited. For example, a styrene resin, an acrylic resin, a styrene-acrylic copolymer, a polyethylene resin, and a polypropylene resin are used. It is preferable to use thermoplastic resins such as resins, vinyl chloride resins, polyester resins, polyamide resins, polyurethane resins, polyvinyl alcohol resins, vinyl ether resins, N-vinyl resins, styrene-butadiene resins.
The binder resin preferably has two weight average molecular weight peaks (referred to as a low molecular weight peak and a high molecular weight peak). Specifically, the low molecular weight peak is in the range of 3,000 to 20,000, the other high molecular weight peak is in the range of 300,000 to 1,500,000, and Mw / Mn is 10 or more. Those are preferred. If the weight average molecular weight peak is within such a range, the toner can be easily fixed, and offset resistance can be improved. The weight average molecular weight of the binder resin is determined by measuring the elution time from the column using a molecular weight measuring device (GPC) and comparing it with a calibration curve prepared in advance using a standard polystyrene resin. be able to.
[0018]
Moreover, in a binder resin, it is preferable to make a softening point into the value within the range of 110-150 degreeC, and it is more preferable to set it as the value within the range of 120-140 degreeC. This is because when the softening point of the binder resin is less than 110 ° C., the obtained toners are fused to each other, and the storage stability may be lowered. On the other hand, if the softening point of the binder resin exceeds 150 ° C., the toner fixability may be poor.
Moreover, it is preferable to make the glass transition point (Tg) of binder resin into the value within the range of 55-70 degreeC, and it is more preferable to set it as the value within the range of 58-68 degreeC. This is because when the glass transition point of the binder resin is less than 55 ° C., the obtained toners are fused to each other, and the storage stability may be lowered. On the other hand, if the glass transition point of the binder resin exceeds 70 ° C., the toner fixability may be poor.
The softening point and glass transition point of the binder resin can be determined from the endothermic peak position and the specific heat change point using a differential scanning calorimeter (DSC).
[0019]
(2) Waxes
In addition, it is preferable to add waxes in order to obtain the effect of fixing property and offset property in the toner.
The type of such wax is not particularly limited, and examples thereof include polyethylene wax, polypropylene wax, fluorine resin wax, Fischer Tropu wax, paraffin wax, ester wax, montan wax, rice wax and the like. One kind alone or a combination of two or more kinds may be mentioned. In addition, when using Fischer-Tropsch wax, the thing whose weight average molecular weight is a value of 1000 or more and has the endothermic bottom peak by DSC in the range of 100-120 degreeC is more preferable. As such Fischer-Tropsch wax, Sazol wax C1 (high molecular weight grade by crystallization of H1, endothermic bottom peak: 106.5 ° C.) available from Sazol, Sazol wax C105 (by C1 fractionation method) Refined product, endothermic bottom peak: 102.1 ° C.), Sazol wax SPRAY (C105 fine particles, endothermic bottom peak: 102.1 ° C.), and the like.
Also, the amount of added wax is not particularly limited. For example, when the total amount of toner is 100% by weight, the added amount of wax is set to a value in the range of 1 to 5% by weight. Is preferred. If the amount of added wax is less than 1% by weight, there is a tendency that offset to the read head, image smearing, etc. cannot be effectively prevented, while if the added amount of wax exceeds 5% by weight. Further, the toners are fused with each other, and the storage stability tends to be lowered.
[0020]
(3) Charge control agent
In addition, in the toner, charge control and charge rising characteristics (indicator of whether to charge to a constant charge level in a short time) are remarkably improved, and charge control is performed from the viewpoint of obtaining excellent durability and stability characteristics. It is preferable to add an agent.
The type of the charge control agent is not particularly limited. For example, positive charge such as nigrosine, a quaternary ammonium salt compound, a resin type charge control agent in which an amine compound is bonded to a resin, and the like. It is preferable to use a charge control agent exhibiting properties.
Further, when the total amount of toner is 100% by weight, the charge control agent is preferably added in a range of 1.5 to 15% by weight. This is because if the amount of the charge control agent added is less than 1.5% by weight, it becomes difficult to stably impart charging characteristics to the toner, resulting in low image density or so-called fogging. This is because the durability may be reduced. On the other hand, if the addition amount of the charge control agent exceeds 15% by weight, there are cases where environmental resistance, particularly charging failure and image failure under high temperature and high humidity, and defects such as photoconductor contamination are likely to occur. .
[0021]
(4) Magnetic powder
In the toner, a known magnetic powder can be dispersed in the toner to constitute a magnetic toner. Preferred magnetic powder is a metal or alloy exhibiting ferromagnetism such as ferrite, magnetite, iron, cobalt, nickel, etc., a compound containing these ferromagnetic elements, or a magnetic element that does not contain ferromagnetic elements but is subjected to an appropriate heat treatment. An alloy that exhibits ferromagnetism can be cited. Moreover, it is preferable to make the average particle diameter of magnetic powder into the value within the range of 0.1-1 micrometer, and it is more preferable to set it as the value within the range of 0.1-0.5 micrometer. This is because the magnetic powder having such an average particle diameter is easy to handle, while it can be uniformly dispersed in the binder resin in the form of fine powder.
Moreover, it is preferable to surface the surface of magnetic powder with surface treatment agents, such as a titanium coupling agent and a silane coupling agent. This is because the surface treatment can improve the hygroscopicity and dispersibility of the magnetic powder.
[0022]
2. External additive
(1) Granular titanium oxide
(1) -1 Average particle size
  Moreover, the average particle diameter of granular titanium oxide is 0.01-0.50 micrometer.Less thanIt is characterized by.
  The reason for this is that if the average particle size of such granular titanium oxide is less than 0.01 μm, it will be difficult to achieve a uniform polishing effect, resulting in charge-up or image flow at high temperatures and high humidity. This is because an image defect occurs. On the other hand, the average particle size of such granular titanium oxide isWhen it becomes 0.50μm or more,This is because the variation in the charge amount of the toner increases, which may cause a decrease in image density and a decrease in durability. Therefore, the average particle size of the granular titanium oxide is more preferably set to a value within the range of 0.02 to 0.4 μm, and further preferably set to a value within the range of 0.05 to 0.3 μm.
  In addition, the average particle diameter of granular titanium oxide is a value of an average primary particle diameter, and it measured as follows. That is, using a magnification of 30,000 times to 100,000 times as appropriate, an electron microscope JSM-880 (manufactured by JEOL Datum) was used to measure the major axis and minor axis of 50 particles, and the average of them. Was calculated.
[0023]
(2) Surface treatment
Further, the surface of the granular titanium oxide is treated with a titanate compound (including a titanium coupling agent). This is because a hydrophobic group can be easily introduced onto the surface of the granular titanium oxide by performing such a surface treatment. Therefore, by using the granular titanium oxide surface-treated in this way, it is possible to prevent the charging characteristics from being deteriorated particularly under high temperature and high humidity conditions.
Here, preferred titanate compounds include isopropyl triisostearoyl titanium, vinyl trimethoxy titanium, naphthyltrimethoxy titanium, phenyl trimethoxy titanium, methyl trimethoxy titanium, ethyl trimethoxy titanium, propyl trimethoxy titanium, isobutyl trimethoxy titanium. , Octadecyltrimethoxytitanium or the like alone or in combination of two or more.
[0024]
(3) Volume resistivity
Further, the volume resistivity of granular titanium oxide is 1 × 10.^FourA value of Ω · cm or more is preferable.
This is because the volume resistivity is 1 × 10.^FourIf the value is less than Ω · cm, there is a relationship with the volume resistivity of the acicular conductive particles, but the charging characteristics under high temperature and high humidity conditions may be significantly reduced.
However, if the volume resistivity of the granular titanium oxide is excessively large, charge-up is likely to occur, and the charging characteristics under low temperature and low humidity conditions may be significantly reduced.
Therefore, the volume resistivity of granular titanium oxide is 1 × 10.^FourΩ · cm to 1 × 10⁷More preferably, the value is within the range of Ω · cm.^FiveΩ · cm to 5 × 10⁶More preferably, the value is within the range of Ω · cm.
[0025]
(4) Addition amount
Moreover, it is preferable that the addition amount of the granular titanium oxide is set to a value within the range of 0.01 to 7 parts by weight with respect to 100 parts by weight of the toner particles.
The reason for this is that when the added amount is less than 0.01 parts by weight, it becomes difficult to effectively exhibit the polishing effect, and the charging characteristics under high temperature and high humidity conditions may be significantly reduced. It is. On the other hand, when the added amount exceeds 7 parts by weight, charge-up is likely to occur, and charging characteristics under low temperature and low humidity conditions may be significantly reduced.
Accordingly, the amount of granular titanium oxide added is more preferably set to a value in the range of 0.1 to 5 parts by weight with respect to 100 parts by weight of the toner particles, and a value in the range of 0.5 to 3 parts by weight. More preferably.
[0026]
(2) Acicular conductive particles
(1) Average particle size
Regarding the average particle diameter of the acicular conductive particles, the major axis is a value in the range of 0.2 to 2.0 μm, and the minor axis is a value in the range of 0.01 to 0.1 μm. . The reason for this is that when the long axis of the needle-like conductive particles is less than 0.2 μm, the aspect ratio with the short axis becomes small, and it may be difficult to control the chargeability of the toner particles. is there. On the other hand, if the major axis of the needle-like conductive particles exceeds 2.0 μm, the aspect ratio with the minor axis increases, and it may be difficult to add the toner particles uniformly to the toner particles. is there. In addition, when the minor axis of the acicular conductive particles is less than 0.01 μm, the mechanical strength of the acicular conductive particles is remarkably lowered, which may make handling difficult. On the other hand, if the minor axis of the acicular conductive particles exceeds 0.2 μm, the aspect ratio with the minor axis becomes small, and it may be difficult to control the chargeability of the toner particles.
Accordingly, it is more preferable that the major axis of the acicular conductive particles is a value in the range of 0.25 to 1.8 μm, and the minor axis is a value in the range of 0.015 to 0.08 μm. More preferably, the long axis of the conductive particles is a value in the range of 0.3 to 1.5 μm and the short axis is a value in the range of 0.018 to 0.06 μm.
[0027]
(2) Volume resistivity
In addition, the volume resistivity of the acicular conductive particles is 1 × 10^-1~ 1x10^FourA value within the range of Ω · cm is preferable.
This is because the volume resistivity of the acicular conductive particles is 1 × 10.^-1This is because if it is less than Ω · cm, the charging characteristics are lowered and the resulting image density may be lowered. On the other hand, the volume resistivity of the acicular conductive particles is 1 × 10.^FourThis is because if it exceeds Ω · cm, charge-up is likely to occur, and it may be difficult to provide a toner for developing an electrostatic latent image that exhibits stable charging characteristics.
Therefore, the volume resistivity of the acicular conductive particles is 1.0-1 × 10^ThreeA value in the range of Ω · cm is more preferable, and 1.0 to 1 × 10²More preferably, the value is within the range of Ω · cm.
The volume resistivity of the acicular conductive particles and the above-described granular titanium oxide was measured as follows. That is, about 5 g of a sample to be measured (for example, acicular conductive particles) is filled in a cell in which 25.4 mm (superscript: 2) electrodes are arranged above and below, and a weight of 1 kg is applied and 1 minute later. The value was measured as a resistance value, and the volume resistivity was calculated from the thickness of the sample at that time. In addition, as a measuring instrument, an Rvanta R6561 digital multimeter was used.
[0028]
(3) Addition amount
Further, the addition amount of the acicular conductive particles is preferably set to a value within the range of 0.01 to 5 parts by weight with respect to 100 parts by weight of the toner particles.
The reason for this is that when the amount added is less than 0.01 parts by weight, it becomes difficult to adjust the charging characteristics, and charge-up is likely to occur, or the charging characteristics under low temperature and low humidity conditions are significantly reduced. It is because there is a case to do. On the other hand, if the amount added exceeds 5 parts by weight, the charging characteristics under high temperature and high humidity conditions may be significantly reduced.
Therefore, the addition amount of the acicular conductive particles is more preferably set to a value within the range of 0.1 to 5 parts by weight with respect to 100 parts by weight of the toner particles, and within a range of 0.5 to 3 parts by weight. More preferably, the value of
[0029]
(3) Addition ratio
Moreover, it is preferable to add the ratio of granular titanium oxide and acicular electroconductive particle within the range of 10: 90-90: 10 by weight ratio, and adding within the range of 20: 80-80: 20. Is more preferable.
This is because if the amount of granular titanium oxide added is less than 10% by weight or the amount of needle-like conductive particles added exceeds 90% by weight, polishing will be insufficient and image flow will occur at high temperature and high humidity. This is because image defects are likely to occur. On the other hand, when the addition amount of granular titanium oxide exceeds 90% by weight or the addition amount of acicular conductive particles is less than 10% by weight, the charge amount of the toner exceeds the appropriate value, which causes charge-up. This is because the charge amount distribution becomes broad, and as a result, the image density is lowered and the durability is deteriorated.
Therefore, the ratio of the granular titanium oxide and the acicular conductive particles is more preferably set to a value in the range of 20:80 to 80:20, and a value in the range of 30:70 to 70:30. More preferably.
[0030]
Here, with reference to FIG. 2 to FIG. 5, the relationship between the addition ratio of the granular titanium oxide / needle-like conductive particles surface-treated with the titanate compound and the charging characteristics, image density, fogging, and image flowability is shown. Each will be explained.
The horizontal axis of FIG. 2 shows the addition ratio (weight ratio) of granular titanium oxide out of the addition ratio of granular titanium oxide / needle-like conductive particles surface-treated with a titanate compound. The vertical axis shows the charge amount (μC / g). The initial charge amount (μC / g) is indicated by a solid line indicated by symbol A, and the charge amount after durability (μC / g) is indicated by a dotted line indicated by symbol B.
As shown in FIG. 2, the addition ratio (weight ratio) of the granular titanium oxide is 90 or less, that is, the addition ratio (weight ratio) of the granular titanium oxide / acicular conductive particles is 10/90 to 90 / If it is in the range of 10, it can be understood that both the initial charge amount and the charge amount after durability are stable. However, when the addition ratio (weight ratio) of the granular titanium oxide exceeds 90, for example, the addition ratio (weight ratio) of the granular titanium oxide / acicular conductive particles is 95/5 to 100/0, It can be understood that a charge-up in which the value of the quantity increases and the value changes greatly after endurance occurs.
Therefore, in order to stabilize the initial charge amount and the charge amount after durability, it is effective to set the addition ratio (weight ratio) of the granular titanium oxide / needle-like conductive particles to a value of 90/10 or less. Is understood.
[0031]
Further, the horizontal axis of FIG. 3 shows the addition ratio (weight ratio) of granular titanium oxide among the addition ratio (weight ratio) of granular titanium oxide / needle-like conductive particles surface-treated with a titanate compound. The vertical axis of FIG. 3 shows the image density (−). The initial image density (−) is indicated by a solid line indicated by symbol A, and the image density (−) after endurance is indicated by a dotted line indicated by symbol B.
As shown in FIG. 3, the addition ratio (weight ratio) of the granular titanium oxide is 90 or less, that is, the addition ratio (weight ratio) of the granular titanium oxide / acicular conductive particles is 10/90 to 90 / If it is in the range of 10, it can be understood that an image density of about 1.40 is obtained both in the initial stage and after the endurance and is stable. However, when the addition ratio (weight ratio) of the granular titanium oxide exceeds 90, for example, the addition ratio (weight ratio) of the granular titanium oxide / acicular conductive particles is 95/5 to 100/0, It can be understood that the image density is lowered to about 1.2 to 1.3 even after the endurance.
Therefore, it is understood that it is effective to set the addition ratio (weight ratio) of granular titanium oxide / needle-like conductive particles to a value of 90/10 or less in order to stabilize the image density after the initial stage and after the endurance. The
[0032]
The horizontal axis of FIG. 4 shows the addition ratio (weight ratio) of granular titanium oxide among the addition ratio (weight ratio) of granular titanium oxide / needle-like conductive particles surface-treated with a titanate compound. The vertical axis in FIG. 4 shows the evaluation point (relative value) for fogging. The initial fog evaluation (relative value) is indicated by a solid line indicated by symbol A, and the fog evaluation (relative value) after durability is indicated by a dotted line indicated by symbol B. In addition, the evaluation score for fogging is calculated by setting the evaluation of ◯ for fogging as 3 points, the evaluation for fogging Δ as 1 point, and the evaluation for fogging × as 0 points.
As shown in FIG. 4, the addition ratio (weight ratio) of the granular titanium oxide is 90 or less, that is, the addition ratio (weight ratio) of the granular titanium oxide / needle-like conductive particles surface-treated with the titanate compound. Is in the range of 10/90 to 90/10, it can be understood that the evaluation point of fogging property is stable at 3 points both in the initial stage and after the endurance. However, when the addition ratio (weight ratio) of the granular titanium oxide exceeds 90, for example, the addition ratio (weight ratio) of the granular titanium oxide / acicular conductive particles is 95/5 to 100/0, In addition, it can be understood that the evaluation score of fogging is lowered to about 0 to 1 even after durability.
Therefore, in order to improve the initial and endurance fogging properties, the addition ratio (weight ratio) of granular titanium oxide / needle-like conductive particles surface-treated with a titanate compound is set to a value of 90/10 or less. It is understood that it is effective to do.
[0033]
The horizontal axis in FIG. 5 shows the addition ratio (weight ratio) of granular titanium oxide among the addition ratio (weight ratio) of granular titanium oxide / needle-like conductive particles surface-treated with a titanate compound. The vertical axis of FIG. 5 shows an evaluation point (relative value) of image flowability. The initial image flowability evaluation (relative value) is indicated by a solid line indicated by symbol A, and the image flowability evaluation (relative value) after endurance is indicated by a dotted line indicated by symbol B. In addition, the evaluation score of fogging property is calculated by assuming that the evaluation ○ of the image flow property is 3 points, the evaluation Δ of the image flow property is 1 point, and the evaluation × of the image flow property is 0 point.
As shown in FIG. 5, the addition ratio (weight ratio) of the granular titanium oxide is a value of 10 or more, that is, the addition ratio (weight ratio) of the granular titanium oxide / needle-like conductive particles surface-treated with the titanate compound. Is in the range of 10/90 to 90/10, it can be understood that the evaluation point of image flowability is stable at 3 points both in the initial stage and after the endurance. However, when the addition ratio (weight ratio) of the granular titanium oxide is less than 10, that is, when the addition ratio (weight ratio) is 5/95 to 0/100, the evaluation point of image flowability at the initial stage and after the endurance. Can be understood to have decreased to about 0 to 1.
Therefore, in order to improve the image flowability at the initial stage and after the endurance, the addition ratio (weight ratio) of the granular titanium oxide / needle-like conductive particles surface-treated with the titanate compound is 10/90 or more. Is understood to be effective.
[0034]
(4) Total amount added
Further, the total addition amount of the granular titanium oxide and the acicular conductive particles is preferably set to a value within the range of 0.5 to 7.0 parts by weight with respect to 100 parts by weight of the toner particles.
The reason for this is that when the total addition amount of the granular titanium oxide and the acicular conductive particles is less than 0.5 parts by weight, the polishing is insufficient, and image flow occurs at high temperature and high humidity, and image defects are likely to occur. Because there is. On the other hand, when the total addition amount of the granular titanium oxide and the acicular conductive particles exceeds 7 parts by weight, the fluidity of the toner is extremely deteriorated. Because there is.
Therefore, it is more preferable that the total addition amount of the granular titanium oxide and the acicular conductive particles is set to a value within the range of 0.7 to 5.0 parts by weight with respect to 100 parts by weight of the toner particles. More preferably, the value is within the range of 9 to 4.0 parts by weight.
[0035]
3. Average particle size
Further, the average particle diameter of the toner is not particularly limited, but for example, a value within the range of 5 to 12 μm is preferable.
This is because when the average particle diameter of the toner is less than 5 μm, the charging characteristics and flow characteristics of the toner may be deteriorated. On the other hand, when the average particle diameter of the toner exceeds 12 μm, the image This is because the characteristics may deteriorate.
Therefore, the average particle diameter of the toner is more preferably set to a value within the range of 6 to 11 μm, and further preferably set to a value within the range of 6 to 9 μm.
[0036]
[Second Embodiment]
  The second embodiment is an image forming method using a toner for developing an electrostatic latent image composed of toner particles and externally added particles. Granular titanium oxide surface-treated with a titanate compound and having an average particle size of 0.01 to less than 0.50 μm, a major axis of 0.2 to 2.0 μm, and a minor axis of 0.01 to 0.1 μmAcicular conductive titanium oxideWhen,And the addition ratio of granular titanium oxide and acicular conductive titanium oxide is a value within the range of 10:90 to 90:10 by weight ratio.And an electrostatic latent image developing toner.
  Hereinafter, the contents already described in the first embodiment will be omitted, and different points will be described as the second embodiment.
[0037]
1. Image forming apparatus
(1) Configuration
In carrying out the image forming method, it can be suitably used for an image forming apparatus 1 as shown in FIG. That is, the image forming apparatus 1 includes a developing device 10, a transfer roller 19, a cleaning blade 13, and the like around a charging type photosensitive drum (photosensitive member) 9 that rotates clockwise in FIG. In addition, a charging unit 8 is provided. The developing device 10 is provided with a developing roller 32. The surface of the developing roller 32 is spaced from the surface of the photosensitive member 9 by a predetermined distance. It is preferable that a predetermined amount of toner is appropriately supplied.
[0038]
Here, an optical transmission mechanism 5 for forming image dots on the surface of the photoconductor 9 is provided above the photoconductor 9. Although this optical transmission mechanism 5 is not shown, the polygon mirror 2 for reflecting the laser light from the laser light source and the surface of the photosensitive member between the charging unit 8 and the developing roller 32 via the reflection mirror 4 by the laser light. An optical system 3 for forming an image dot is preferably configured.
In addition, a base portion 54 in which a control circuit 71 for controlling the device, which will be described later, is housed is provided at the lower portion of the image forming apparatus 1, and a recording paper container 55 is provided from the outside above the base portion 54. It is arranged to be detachable. The recording paper container 55 is preferably provided with a storage 14 for storing recording paper before transfer.
The recording paper placed on the pressing spring 52 is transported by the transport rollers 53 and 15 to the registration roller 18 provided facing the auxiliary roller 30 through the passages 16 and 17. Has been.
[0039]
Further, a front door 50 is disposed on the right side of the image forming apparatus 1 so as to be openable and closable, and the recording paper placed on the front door is configured to be conveyed to the passage 17 by the conveyance roller 51. On the left side of the image forming apparatus 1, a fixing unit is configured by fixing rollers 23 and 24, and the recording paper that has passed between the photoreceptor 9 and the transfer roller 19 is fixed by these fixing rollers 23 and 24.
In addition, it is preferable that the recording paper after fixing passes through the passage 27 by the conveying rollers 25 and 26 and is further accumulated in the transferred recording paper accumulator 6 by the rollers 28 and 29.
Furthermore, it is preferable that a display unit 47 for displaying various information, an installation switch 48, and a power switch 49 are provided on the upper part of the image recording apparatus 1.
[0040]
(2) Operation
In the image recording apparatus 1 configured as described above, the main motor (not shown) starts driving by opening and closing the power switch 49, and the photosensitive member 9 is rotated clockwise by the start switch (not shown). The optical transmission mechanism 5 is preferably configured so that an image can be formed on the surface of the photoreceptor 9.
The formed image is developed by the developing roller 32 of the developing device 10, and the developed toner image is transferred to the recording paper by the transfer roller 19. Further, the recording paper onto which the toner has been transferred is fixed and fixed by the fixing rollers 23 and 24, and is conveyed to the stacker 6 by the rollers 25, 27, 28, and 29 and is collected. The toner that has not been developed by the developing roller 32 is collected by the cleaning blade 13.
Therefore, in a positively charged photoreceptor, an image is formed using the toner to which anatase-type titanium oxide and rutile-type titanium oxide are externally added as described above, thereby effectively preventing toner adhesion and image flow over a long period of time. Can do.
[0041]
2. Toner for electrostatic latent image development
The electrostatic latent image developing toner used in the second embodiment is composed of granular titanium oxide having an average particle size of 0.01 to less than 0.50 μm, which is surface-treated with a titanate coupling agent, with respect to toner particles. Any electrostatic latent image developing toner that is externally treated with needle-like conductive particles having a major axis of 0.2 to 2.0 μm and a minor axis of 0.01 to 0.1 μm is preferably used. However, the details can be the same as those described in the first embodiment.
[0042]
【Example】
Hereinafter, the present invention will be described in more detail based on examples. Various studies were conducted from the following viewpoints.
(1) The influence of the addition of both granular titanium oxide and needle-like conductive particles on the toner was varied and the effects were examined.
(2) The average particle diameter of granular titanium oxide, the long axis and the short axis of acicular conductive particles were combined, and the effects were examined.
Needless to say, the following description exemplifies the present invention, and the scope of the present invention is not limited to the following description without any particular reason.
[0043]
[Example 1]
1. Toner creation
(1) Preparation of toner particles
Styrene / acrylic resin, polyethylene wax, charge control agent, and magnetic powder were melt-kneaded with a twin screw extruder so as to have the following blending ratio, and then cooled. Subsequently, toner particles having an average particle size of 7 μm were obtained through a pulverization step and a classification step.
(1) 56 parts by weight of styrene / acrylic resin
(2) 3 parts by weight of polyethylene wax
(3) Charge control agent (quaternary ammonium salt) 1 part by weight
(4) 40 parts by weight of magnetic powder (magnetite)
[0044]
(2) Addition of external additive particles
With respect to 100 parts by weight of the obtained toner particles, granular titanium oxide (granular rutile type titanium oxide surface-treated with methyltrimethoxytitanium, average particle size: 0.25 μm) and acicular conductive particles (Sn₂Toner was prepared by uniformly externally adding needle-like titanium oxide surface-doped with O / Sb (major axis: 1 μm, minor axis: 0.05 μm) to the following composition. The weight ratio of the granular titanium oxide and the acicular conductive particles added to 100 parts by weight of the prepared toner particles is as shown in Table 1.
(1) Toner particles 100 parts by weight
(2) Granular titanium oxide 0.3 parts by weight
(3) 2.7 parts by weight of acicular conductive particles
[0045]
2. Toner rating
The obtained toner was constituted as a magnetic one-component developer, and an initial image characteristic, durability, and image flow were evaluated using a Kyocera page printer (FS-3750) equipped with an a-Si photosensitive member. Was measured. The obtained results are shown in Table 2.
[0046]
(1) Charging characteristics
5 parts by weight of the obtained toner and 100 parts by weight of a ferrite carrier were mixed, and the charge amount (μC / g) when frictionally charged for 60 minutes in a normal environment was defined as the initial charge amount. In addition, a toner is used as a magnetic one-component developer using toner, and a toner (developing roller in the developing unit) is used when 100,000 sheets are continuously fed using a Kyocera page printer (FS-3750) equipped with an a-Si photosensitive member. The charge amount of the toner on the roller was defined as the charge amount after durability.
In addition, each charge amount was measured using blow-off powder charge amount measuring device TB-200 (manufactured by Toshiba Chemical Co., Ltd.). That is, Tona-4g and ferrite carrier 100g were put in a plastic container, and then mixed and stirred for 30 minutes in a ball mill to prepare a developer. 0.2 g of the obtained developer was weighed on a 500 mesh stainless steel mesh and set in the measuring apparatus, and then the charge amount was measured under the conditions of a blow pressure of 0.8 kg and a blow time of 30 seconds. .
[0047]
(2) Image characteristics
The obtained toner was used as a magnetic one-component developer, and an image characteristic was evaluated using a page printer (FS-3750) manufactured by Kyocera equipped with an a-Si photosensitive member. In a normal environment (23 ± 3 ° C., 50 ± 10% Rh), an image evaluation pattern (solid pattern) was printed at the initial stage to obtain an initial image. Next, after 100,000 sheets were continuously passed, an image evaluation pattern (solid pattern) was printed again to obtain a durable image. And the image density in the obtained initial image and durable image was measured using the Macbeth reflection densitometer (model number: rRD918) made from Macbeth. At the same time, the fog (printability on the background) was visually observed and evaluated according to the following criteria.
In the evaluation of image characteristics (image density and fog), A4 size 64 g paper was used as continuous paper, and a standard image with a printing rate of 5% was output.
(Image density evaluation criteria)
○: A value of 1.4 or more.
Δ: 1.30 to less than 1.40
X: Less than 1.30
(Fog evaluation criteria)
○: No fogging occurred.
Δ: Slight fogging occurs.
X: Remarkable fog is generated.
[0048]
(3) Image flow
Using a Kyocera page printer (FS-3750) equipped with an a-Si photosensitive member and using the obtained toner as a magnetic one-component developer, continuous 5,000 sheets under normal environmental conditions (20 ° C., 65% RH) I went through the paper. Next, the obtained toner is left overnight under high temperature and high humidity environment conditions (33 ° C., 85% RH), and then an image evaluation pattern is printed and the level of image flow is visually observed. According to the following criteria: evaluated.
In the image flow evaluation, A4 size 64 g paper was used as continuous paper, and a standard image with a printing rate of 5% was output.
○: No image flow was observed, and the image evaluation pattern was accurately reproduced.
Δ: Some image flow is recognized, and a part of the image evaluation pattern is not reproduced.
X: A little remarkable image flow is recognized, and the reproducibility of the image evaluation pattern is inferior.
[0049]
[Examples 2-7 and Comparative Examples 1-2]
As shown in Table 1, a toner was prepared and evaluated in the same manner as in Example 1 except that the addition ratio of granular titanium oxide and acicular conductive particles was changed. The obtained results are shown in Table 2 and FIGS.
[0050]
[Table 1]

[0051]
[Table 2]

[0052]
[Examples 8 to 18 and Comparative Examples 3 to 8]
As shown in Table 3, a toner was prepared and evaluated in the same manner as in Example 1 except that the average particle diameter of the granular titanium oxide and the size (major axis and minor axis) of the acicular conductive particles were changed. . The results obtained are shown in Table 4.
[0053]
[Table 3]

[0054]
[Table 4]

[0055]
【The invention's effect】
According to the electrostatic latent image developing toner of the present invention and the image forming method using the same, granular titanium oxide having an average particle size of 0.01 to less than 0.50 μm and surface treated with a titanate compound, and a long axis By adding externally treated needle-like conductive particles having a particle diameter of 0.2-2.0 μm and a minor axis of 0.01-0.1 μm to the toner particles, excellent polishing power can be exhibited and charged up. And the occurrence of image defects in the image flow is significantly reduced.
In addition, since specific granular titanium oxide and acicular conductive particles are added, charging properties with excellent durability and stability can be imparted, and high-quality images can be obtained at any temperature and humidity. It came to be obtained stably.
[0056]
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an image forming apparatus to which an electrostatic latent image developing toner of the present invention is applied.
FIG. 2 is a diagram for explaining the relationship between the charging ratio and the addition ratio of granular titanium oxide / needle-like conductive particles surface-treated with a titanate compound.
FIG. 3 is a diagram for explaining a relationship between an addition ratio of granular titanium oxide / needle-like conductive particles surface-treated with a titanate compound and image density.
FIG. 4 is a diagram provided for explaining the relationship between the addition ratio of granular titanium oxide / needle-like conductive particles surface-treated with a titanate compound and fogging properties.
FIG. 5 is a diagram for explaining the relationship between the addition ratio of granular titanium oxide / needle-like conductive particles surface-treated with a titanate compound and image flowability.
[0057]
[Explanation of symbols]
1: Image forming apparatus
2: Polygon mirror
5: Optical transmission mechanism
7: Upper door
9: Photoconductor
10: Developer
31: Toner container
32: Developing roller
33: Supply roller
39: Toner sensor
47: Display section

Claims (5)

Toner particles, granular titanium oxide having an average particle size of 0.01 to less than 0.50 μm surface-treated with a titanate compound, a major axis of 0.2 to 2.0 μm, and a minor axis of 0.01 to 0.1 μm of acicular conductive titanium oxide is externally added,
A toner for developing an electrostatic latent image , wherein an addition ratio of the granular titanium oxide and the acicular conductive titanium oxide is set to a value within a range of 10:90 to 90:10 by weight . _2. The electrostatic latent image developing toner according to claim 1, wherein the acicular conductive titanium oxide is titanium oxide doped with tin oxide (SnO ₂ ) and antimony (Sb). The total addition amount of the titanium oxide and acicular conductive titanium oxide is set to a value within a range of 0.5 to 7.0 parts by weight with respect to 100 parts by weight of the toner particles. 2. The electrostatic latent image developing toner according to 2. The electrostatic latent image according to any one of claims 1 to 3 , wherein the granular titanium oxide is anatase-type titanium oxide and rutile-type titanium oxide, or titanium oxide having any one of crystal structures. Toner for image development. An image forming method using toner for developing an electrostatic latent image comprising toner particles and externally added particles, wherein the toner particles are surface-treated with a titanate compound as the toner for developing an electrostatic latent image. a particulate titanium oxide having an average particle size of less than 0.01~0.50μm was, long axis 0.2 to 2.0 [mu] m, a minor axis and the needle-like conductive titanium oxide of 0.01 to 0.1 m, the An electrostatic latent image developing toner that is externally added and has an addition ratio between the granular titanium oxide and the acicular conductive titanium oxide in a weight ratio of 10:90 to 90:10. An image forming method characterized by being used.

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