JP4258356B2 - Electrostatic latent image developer carrier and manufacturing method thereof, electrostatic latent image developer, image forming method, and image forming apparatus - Google Patents

Description

  The present invention relates to a carrier for an electrostatic latent image developer used for developing an electrostatic latent image in electrophotography and electrostatic recording, a manufacturing method thereof, an electrostatic latent image developer, an image forming method, and The present invention relates to an image forming apparatus.

  Conventionally, in electrophotography, an electrostatic latent image is formed on a photoreceptor or an electrostatic recording body (single electrostatic latent image) using various means, and a test called toner is applied to the electrostatic latent image. A method of developing an electrostatic latent image by attaching electroconductive fine particles is generally used. In this development, carrier particles called a carrier are mixed with toner particles, and both are frictionally charged with each other to impart an appropriate amount of positive or negative charge to the toner.

  The carriers are generally classified into a coating carrier having a coating layer (resin coating layer) on the surface and a non-coating carrier having no coating layer on the surface. Since the carrier is superior, various types of coated carriers have been developed and put into practical use. There are various properties required for the coated carrier, but it is required to stably impart appropriate chargeability (charge amount and charge distribution) to the toner and to maintain the appropriate and stable chargeability over a long period of time. . For this purpose, it is important that the carrier has suitable electrical properties and has high resistance to environmental changes such as humidity and temperature, impact resistance, and friction resistance, and the ability to impart chargeability does not change over the long term. Various film carriers have been proposed.

  For solving some of these problems, for example, a copolymer of a nitrogen-containing fluorinated alkyl (meth) acrylate and a vinyl monomer, or a fluorinated alkyl (meth) acrylate and a nitrogen-containing vinyl monomer It has been proposed to obtain a coating carrier having a relatively long life by coating the surface of the carrier core material with a copolymer (see, for example, Patent Documents 1 to 3).

  It has also been proposed that a polyamide resin or a melamine resin is coated on the surface of the carrier core material and further cured to obtain a coated carrier having a relatively hard coating (for example, see Patent Documents 4 and 5).

  However, any of the above methods has a feature in selecting the material of the carrier, and from a different viewpoint, a technique capable of improving the above disadvantages is required. Accordingly, there is a demand for structurally improving the carrier to further improve the chargeability imparting ability and to maintain it for a long period of time.

  Further, the conventional coated carrier as described above is not satisfactory because the contamination of the toner surface on the carrier surface cannot be prevented. In other words, the carrier is required to have a function of stably supplying a charge to the toner over a long period of time simultaneously with the toner transport function, but the carrier surface is contaminated with the toner, and the latter function does not work effectively. .

  In order to prevent such spent, it is preferable to use a silicone resin or a fluorine resin as a coating resin (see, for example, Patent Documents 6 and 7). However, even if these resins are used at the same time as the polymer or resin to coat the surface of the carrier core material, a large amount of silicone resin or fluorine-based resin is present in the upper layer (surface side) of the coating layer. In the long-term use, the coating is worn from the surface of the carrier, and eventually the silicone resin and the fluorine-based resin are lost, and in the long term, the spent prevention is not sufficient. Therefore, also from this point, the structural improvement of the carrier is expected.

In connection with the drawbacks of the carrier described above, the present inventors have proposed a carrier that has a structural feature but does not limit the resin to a specific type (for example, see Patent Document 8). ). This is a carrier in which resin particles insoluble in a solvent and conductive fine powder are contained in a coating layer (resin coating layer). However, although this technique also solves the various problems to some extent, it is difficult to say that this technique is sufficiently stable against environmental changes such as humidity and temperature.
JP 61-80161 A JP 61-80162 A JP 61-80163 A JP-A-1-118150 Japanese Patent Laid-Open No. 2-79862 JP-A-60-186844 JP-A 64-13560 JP-A-9-269614

The object of the present invention is to solve the above-mentioned problems of the prior art.
That is, the first object of the present invention is excellent in the ability to impart appropriate and stable chargeability to the toner regardless of environmental changes such as humidity and temperature, and has durability capable of maintaining it for a long period of time. Another object of the present invention is to provide a carrier for an electrostatic latent image developer having a structure having a structure capable of preventing spent on the carrier surface due to toner on a long term basis.

  The second object of the present invention is to provide a suitable method for producing such a carrier.

  A third object of the present invention is to provide an electrostatic latent image developer using such a carrier.

  A fourth object of the present invention is to provide an image forming method capable of forming a high-quality image with an electrostatic latent image developer containing such a carrier.

  A fifth object of the present invention is to provide an image forming apparatus using an electrostatic latent image developer containing such a carrier.

  In order to improve the above-mentioned drawbacks in the prior art, the present inventors have intensively studied and studied the carrier for electrostatic latent image developer mainly from a different point of view. By adopting the configuration, we have successfully solved the above problems.

That is, the present invention
<1> A resin coating layer in which composite resin particles containing at least inorganic particles and a melamine resin as constituent components and conductive fine powder are dispersed and contained in a matrix resin is formed on the surface of the core material. The electrostatic latent image developer carrier.

<2> The electrostatic latent image developer carrier according to <1>, wherein the composite resin particles have a volume average particle diameter in a range of 0.05 to 1 μm.

<3> The number average particle diameter of the composite resin particles is taken as d _50, the particle size distribution of the composite resin particles, 1/2 × rate and 2 × d ₅₀ or more percentage of d ₅₀ below particles, The electrostatic latent image developer carrier according to <1> or <2>, wherein each carrier is 20% by number or less.

<4> When the average thickness of the resin coating layer is 1, the volume average particle diameter of the composite resin particles is 1 or less. The static according to any one of <1> to <3> This is a carrier for an electrostatic latent image developer.

<5> The electrostatic latent image developer according to any one of <1> to <4>, wherein the inorganic particles contained in the composite resin particles are partially exposed on the surface of the composite resin particles. Is a career.

<6> Electrostatic latent formed by forming on the surface of a core material a resin coating layer in which composite resin particles containing at least inorganic particles and melamine resin as constituent components and conductive fine powder are dispersed in a matrix resin. An electrostatic latent image developer comprising an image developer carrier and toner.

<7> The electrostatic latent image developer according to <6>, wherein the toner has a shape factor SF1 in the range of 100 to 140.

<8> Development means for developing the electrostatic latent image on the surface of the electrostatic latent image carrier using a developer charged with a developer containing at least toner and a carrier formed on the surface of the developer carrier. In the image forming apparatus, the carrier has, on the surface of the core material, a resin coating layer in which composite resin particles containing at least inorganic particles and melamine resin as constituent components and conductive fine powder are dispersed and contained in a matrix resin. The image forming apparatus is a carrier formed.

<9> Mixing matrix resin, composite resin particles containing inorganic particles and melamine resin as constituents, and conductive fine powder in a solvent having at least the property of dissolving matrix resin but not dissolving composite resin particles containing inorganic particles And a step of preparing a resin coating layer forming solution in which the composite resin particles are dispersed, and a step of applying the resin coating layer forming solution to the surface of the core material and removing the solvent. A method for producing a carrier for an electrostatic latent image developer.

<10> In an image forming method including a developing step of developing an electrostatic latent image on the surface of an electrostatic latent image carrier using at least a developer including a toner and a carrier formed on the surface of the developer carrier. As the carrier, a carrier formed by forming on the surface of a core material a resin coating layer in which composite resin particles containing at least inorganic particles and melamine resin as constituent components and conductive fine powder are dispersed and contained in a matrix resin. It is an image forming method characterized by being used.

  The carrier for an electrostatic latent image developer of the present invention is excellent in ability to impart appropriate and stable chargeability to toner in each environment, and has a structure having durability capable of maintaining it for a long period of time. In addition, it has a structure that can prevent spent on the carrier surface due to toner for a long period of time. Therefore, halftone reproducibility is achieved by an electrostatic latent image developer, an image forming method, and an image forming apparatus using the same. It is possible to maintain an electrophotographic image with good image quality for a long period of time. In addition, according to the present invention, a suitable form of the carrier can be easily manufactured.

Hereinafter, the present invention will be described in more detail with reference to embodiments.
<Electrostatic latent image developer carrier and manufacturing method thereof>
The carrier for an electrostatic latent image developer of the present invention comprises a resin coating layer in which composite resin particles containing at least inorganic particles and melamine resin as constituent components and conductive fine powder are dispersed and contained in a matrix resin. It is formed on the surface of the material.

As a result of intensive studies on the carrier structure disclosed in JP-A-9-269614, the present inventors have found that the charging characteristics of the resin particles dispersed in the resin coating layer affect the carrier characteristics, and the resin particles It was confirmed that the charge-providing property of the glass was likely to fluctuate due to environmental changes such as humidity and temperature. As a result of further investigations, it was found that the charging characteristics can be kept more stable by using the resin particles as composite resin particles containing inorganic particles and a melamine resin as constituent components. Hereinafter, in the present specification, the above-mentioned “composite resin particles containing inorganic particles and melamine resin as constituent components” are also referred to as “composite resin particles containing inorganic particles”.

That is, in the resin particle single composition, the charging characteristics are likely to fluctuate due to environmental changes such as humidity and temperature. However, the presence of the inorganic particles in the melamine resin particles stabilizes the chargeability due to the action of the inorganic particles although details are unknown. It seems to be. In this case, the effect can be expected to some extent by simply dispersing the inorganic particles in the matrix resin of the coating resin layer. However, the inorganic particles are uniformly dispersed in the coating resin layer, so that It is considered that the charging characteristics can be further stabilized.

In the present invention, by including the inorganic particles in the melamine resin particles from the above viewpoint, the inorganic particles are uniformly present in the resin coating layer, and the stabilization of charging characteristics by the addition of the inorganic particles is maximized. It has been found that it can be demonstrated.

  One embodiment of the carrier for an electrostatic latent image developer of the present invention is shown in FIG. The carrier 1 is formed by forming a resin coating layer 20 in which composite resin particles 22 including inorganic particles and a conductive fine powder 23 are dispersed in a matrix resin 21 on the surface of the core material 30.

  The matrix resin 21 and the resin of the composite resin particle 22 containing inorganic particles may be of the same type as long as they can be classified into such forms depending on the manufacturing method, molecular weight, etc. From the viewpoint of achieving a plurality of functions in a balanced manner, different types are preferable.

  The composite resin particles 22 containing inorganic particles are preferably dispersed as uniformly as possible in the matrix resin 21 in the thickness direction of the resin coating layer 20 and in the tangential direction of the carrier surface. At the same time, the matrix resin 21 of the resin coating layer 20 is preferably uniform as well. Thereby, the charge imparting ability and the spent prevention function work uniformly throughout the carrier, and the functions can be stably exhibited. Moreover, even if the resin coating layer 20 is worn from the surface after long-term use, the same surface composition as when not in use can always be maintained, and the above functions can be maintained for a long time.

  The matrix resin 21 and the resin of the composite resin particle 22 containing inorganic particles are highly compatible (that is, when the raw material of the matrix resin 21 and the raw material resin of the composite resin particle 22 containing inorganic particles are mixed, Is preferable that it can improve the uniformity of dispersion. In particular, the composite resin particles 22 containing inorganic particles can be uniformly dispersed with a primary particle size, which is preferable.

In order to produce the fine particle form of the composite resin particle 22 including the inorganic particles dispersed in the resin coating layer 20, any method may be used as long as an appropriate particle size as described later is obtained. The composite resin particles 22 containing inorganic particles are preferably in the form of fine particles before being mixed and dispersed in the matrix resin 21. This is because it is easy to ensure the uniformity of the mixed dispersion and to confirm the uniformity of the dispersion.

In the present invention, a melamine resin that is thermosetting and has a high ability to impart negative charge to the toner is used as the resin constituting the composite resin particles.

  Examples of the inorganic particles include silica, alumina, titania, zinc oxide, strontium titanate, cerium oxide, and calcium carbonate. Silica is preferable for the purpose of adjusting the charge imparting ability.

  The inorganic particles are preferably hydrophilic from the viewpoint of dispersibility, and the particle diameter is preferably in the range of 5 to 100 nm (primary particle diameter) and the shape is irregular.

  As a method of producing composite resin particles containing inorganic particles in the present invention, a method of producing a granular resin using a polymerization method such as suspension polymerization, emulsion polymerization, suspension polymerization, etc., dispersing a monomer or oligomer in a poor solvent Then, a method of granulating by surface tension while performing a crosslinking reaction, a method of mixing and reacting a low molecular component and a crosslinking agent by melt kneading, etc., and then pulverizing to a predetermined particle size by wind force or mechanical force, etc. Can be mentioned.

A specific manufacturing method is illustrated below.
Although a manufacturing method is not limited to the following, the spherical composite melamine resin particle (composite resin particle) which contains a silica as an inorganic particle can be manufactured by the following process (a) and (b), for example.

(A) In an aqueous medium, a melamine compound and an aldehyde compound are reacted under basic conditions under a suspension of colloidal silica having an average particle size of 5 to 70 nm, and the initial stage of a melamine resin soluble in water A step of generating an aqueous solution of the condensate, and a step of adding spherical acid melamine resin particles by adding an acid catalyst to the aqueous solution obtained in steps (b) and (a).

  As the melamine compound used in the step (a), known compounds such as melamine and substituted melamine compounds in which the hydrogen of the amino group of melamine is substituted with an alkyl group, an alkenyl group, or a phenyl group can be used. Of these, inexpensive melamine is most preferred.

Examples of the aldehyde compound include formaldehyde, paraformaldehyde, acetaldehyde, benzaldehyde, furfural and the like, but formaldehyde and paraformaldehyde that are inexpensive and have good reactivity with the melamine compound are preferable.
As an aldehyde compound, it is preferable to mix | blend 1.1-6.0 mol per effective aldehyde group with respect to 1 mol of said melamine compounds, especially 1.2-4.0 mol.

  As the colloidal silica, one having an average particle diameter in the range of 5 to 70 nm is used. More preferably, it is the range of 5-50 nm, More preferably, it is the range of 5-30 nm. Although powdered colloidal silica such as precipitated silica powder and vapor phase method silica powder can be used, it is preferable to use a colloidal silica sol stably dispersed to the primary particle level in a medium.

  When the average particle diameter of colloidal silica exceeds 70 nm, the composite melamine resin particles precipitated in the step (b) may be difficult to become spherical particles. If it is less than 5 nm, the particle size distribution may be difficult to control sharply. In general, the average particle size of the spherical composite melamine resin particles becomes smaller as the melamine resin concentration is lower and the average particle size of the colloidal silica is smaller.

  The amount of colloidal silica added is preferably in the range of 0.5 to 100 parts by mass, particularly in the range of 1 to 50 parts by mass with respect to 100 parts by mass of the melamine compound. When the addition amount is less than 0.5 parts by mass, it is difficult to obtain spherical composite melamine resin particles in the step (b). Further, even when the addition amount exceeds 100 parts by mass, spherical cured melamine resin particles can be obtained, but in this case, compared with the spherical composite melamine resin particles, fine and non-spherical aggregated particles are by-produced, which is not preferable.

  If necessary, the spherical composite melamine resin particles may be surface-coated with inorganic compound particles. For example, spherical composite melamine resin particles and inorganic compound particles may be mixed directly or in an aqueous medium. Further, it is possible to cover the surface with inorganic compound particles by a general vapor deposition method such as a vacuum vapor deposition method, a sputtering method, or an ion plating method.

Furthermore, you may surface-treat the colloidal silica which exists in the spherical composite melamine resin particle surface as needed. For example, the surface treatment can be performed with a silicon compound represented by the following formulas (I) to (III).
R ₁ Si (X) ₃ (I)
R ₁ R ₂ Si (X) ₂ ... (II)
R ₁ R ₂ R ₃ SiX (III)

In each of the above formulas, R ₁ represents an alkyl group having 1 to 20 carbon atoms or a perfluoroalkyl group, and R ₂ and R ₃ are each a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, a perfluoroalkyl group, Or represents an aryl group, and X represents a chlorine atom, an alkoxy group, an NCO group, or an acetoxy group.

  By such surface treatment, it is possible to prevent the occurrence of comet and filming on the surface of the photosensitive member, and to improve the dispersibility and adhesion to the toner, as well as the charging stability and charge exchange property associated with the hydrophobicity control. Expect more.

Here, the following can be illustrated as a processing agent (coupling agent) used for the said surface treatment.
Examples of the compound represented by the formula (I) include CH ₃ Si (Cl) ₃ , CH ₃ Si (OCH ₃ ) ₃ , CH ₃ Si (OC ₂ H ₅ ) ₃ , and CH ₃ CH ₂ Si (OCH ₃ ) _3. CH ₃ (CH ₂ ) ₂ Si (OCH ₃ ) ₃ , CH ₃ (CH ₂ ) ₃ Si (OCH ₃ ) ₃ , CH ₃ (CH ₂ ) ₄ Si (OCH ₃ ) ₃ , CH ₃ (CH ₂ ) ₅ Si (OCH ₃ ) ₃ , CH ₃ (CH ₂ ) ₆ Si (OCH ₃ ) ₃ , CH ₃ (CH ₂ ) ₇ Si (OCH ₃ ) ₃ , CH ₃ (CH ₂ ) ₈ Si (OCH ₃ ) ₃ , CH ₃ (CH ₂ ) ₉ Si (OCH ₃ ) ₃ , CH ₃ (CH ₂ ) ₁₀ Si (OCH ₃ ) ₃ , CH ₃ (CH ₂ ) ₁₁ Si (OCH ₃ ) ₃ , CH ₃ (CH ₂ ) ₁₂ Si ( _{OCH 3) 3, CH 3 (} CH 2) 13 Si (OCH 3) 3, CH 3 (CH 2) 14 Si (OCH 3) 3, CH 3 (CH 2) 15 Si _{OCH 3) 3, CH 3 (} CH 2) 16 Si (OCH 3) 3, CH 3 (CH 2) 17 Si (OCH 3) 3, CH 3 (CH 2) 18 Si (OCH 3) 3, CH 3 ( CH ₂ ) ₁₉ Si (OCH ₃ ) ₃ , CH ₃ (CH ₂ ) ₅ Si (OCO ₂ H ₅ ) ₃ , CH ₃ (CH ₂ ) ₆ Si (OCO ₂ H ₅ ) ₃ , CH ₃ (CH ₂ ) ₇ Si (OCO ₂ H ₅ ) ₃ , CH ₃ (CH ₂ ) ₈ Si (OCO ₂ H ₅ ) ₃ , CH ₃ (CH ₂ ) ₉ Si (OCO ₂ H ₅ ) ₃ , CH ₃ (CH ₂ ) ₁₀ Si ( OCO ₂ H ₅ ) ₃ , CH ₃ (CH ₂ ) ₁₁ Si (OCO ₂ H ₅ ) ₃ , CH ₃ (CH ₂ ) ₁₂ Si (OCO ₂ H ₅ ) ₃ , CH ₃ (CH ₂ ) ₁₃ Si (OCO ₂ H ₅ ) ₃ , CH ₃ (CH ₂ ) ₁₄ Si (OCO ₂ H ₅ ) ₃ , CH ₃ (CH ₂ ) ₁₅ Si (OCO ₂ H ₅ ) ₃ , CH ₃ (CH ₂ ) ₁₆ Si (OCO) _{2 H 5) 3, CH 3} (CH 2) 17 Si (OCO 2 H 5) 3, CH 3 (CH 2) 18 Si (OCO 2 H 5) 3, CH 3 (CH 2) 19 Si (OCO 2 H ₅ ) ₃ , CF ₃ Si (OCH ₃ ) ₃ , CH ₃ Si (NCO) _{3 and the} like.

Examples of the compound represented by the formula (II) include (CH ₃ ) ₂ SiC ₁₂ , (CH ₃ ) ₂ Si (OCH ₃ ) ₂ , (CH ₃ ) ₂ Si (OC ₂ H ₅ ) ₂ , (CH ₃ ). (CH ₃ CH ₂ ) Si (OCH ₃ ) ₂ , (CH ₃ ) [CH ₃ (CH ₂ ) ₂ ] Si (OCH ₃ ) ₂ , (CH ₃ ) [CH ₃ (CH ₂ ) ₃ ] Si (OCH ₃ ) ₂ , (CH ₃ ) [CH ₃ (CH ₂ ) ₄ ] Si (OCH ₃ ) ₂ , (CH ₃ ) [CH ₃ (CH ₂ ) ₅ ] Si (OCH ₃ ) ₂ , (CH ₃ ) [CH ₃ (CH ₂ ) ₆ ] Si (OCH ₃ ) ₂ , (CH ₃ ) [CH ₃ (CH ₂ ) ₇ ] Si (OCH ₃ ) ₂ , (CH ₃ ) [CH ₃ (CH ₂ ) ₈ ] Si (OCH ₃ ) ₂ , (CH ₃ ) [CH ₃ (CH ₂ ) ₉ ] Si (OCH ₃ ) ₂ , (CH ₃ ) [CH ₃ (CH ₂ ) ₁₀ ] Si (OCH ₃ ) ₂ , (CH ₃ ) [CH ₃ (CH _{2 11} ] Si (OCH ₃ ) ₂ , (CH ₃ ) [CH ₃ (CH ₂ ) ₁₂ ] Si (OCH ₃ ) ₂ , (CH ₃ ) [CH ₃ (CH ₂ ) ₁₃ ] Si (OCH ₃ ) ₂ , (CH ₃ ) [CH ₃ (CH ₂ ) ₁₄ ] Si (OCH ₃ ) ₂ , (CH ₃ ) [CH ₃ (CH ₂ ) ₁₅ ] Si (OCH ₃ ) ₂ , (CH ₃ ) [CH ₃ (CH ₂ ) ₁₆ ] Si (OCH ₃ ) ₂ , (CH ₃ ) [CH ₃ (CH ₂ ) ₁₇ ] Si (OCH ₃ ) ₂ , (CH ₃ ) [CH ₃ (CH ₂ ) ₁₈ ] Si (OCH ₃ ) ₂ , (CH ₃ ) [CH ₃ (CH ₂ ) ₁₉ ] Si (OCH ₃ ) ₂ , (CH) ₂ Si (NCO) _{2 and the} like.

Examples of the compound represented by the formula (III) include (CH ₃ ) ₃ SiCl, (CH ₃ ) ₃ Si (OCH ₃ ), (CH ₃ ) ₃ Si (OC ₂ H ₅ ), (CH ₃ ) ₂ (CH _{3 CH 2) Si (OCH 3} ), (CH 3) 2 [CH 3 (CH 2) 2] Si (OCH 3), (CH 3) 2 [CH 3 (CH 2) 3] Si (OCH 3), (CH ₃ ) ₂ [CH ₃ (CH ₂ ) ₄ ] Si (OCH ₃ ), (CH ₃ ) ₂ [CH ₃ (CH ₂ ) ₅ ] Si (OCH ₃ ), (CH ₃ ) ₂ [CH ₃ (CH ₂ ) ₆ ] Si (OCH ₃ ), (CH ₃ ) ₂ [CH ₃ (CH ₂ ) ₇ ] Si (OCH ₃ ), (CH ₃ ) ₂ [CH ₃ (CH ₂ ) ₈ ] Si (OCH ₃ ), (CH ₃ ) ₂ [CH ₃ (CH ₂ ) ₉ ] Si (OCH ₃ ), (CH ₃ ) ₂ [CH ₃ (CH ₂ ) ₁₀ ] Si (OCH ₃ ), (CH ₃ ) ₂ [CH ₃ (CH ₂ ) ₁₁ ] Si (OCH ₃ ), (CH ₃ ) ₂ [CH ₃ (CH ₂ ) ₁₂ ] Si (OCH ₃ ), (CH ₃ ) ₂ [CH ₃ (CH ₂ ) ₁₃ ] Si (OCH ₃ ), (CH ₃ ) ₂ [CH ₃ (CH ₂ ) ₁₄ ] Si (OCH ₃ ), (CH ₃ ) ₂ [CH ₃ (CH ₂ ) ₁₅ ] Si (OCH ₃ ), (CH ₃ ) ₂ [CH ₃ (CH ₂ ) ₁₆ ] Si (OCH ₃ ), (CH ₃ ) ₂ [CH ₃ (CH ₂ ) ₁₇ ] Si (OCH ₃ ), (CH ₃ ) ₂ [CH ₃ (CH ₂ ) ₁₈ ] Si (OCH ₃ ), (CH ₃ ) ₂ [CH ₃ (CH ₂ ) ₁₉ ] Si (OCH ₃ ) and the like.

Among these, those represented by the above formula (I) are preferable from the viewpoint of increasing the charge amount, and CH ₃ (CH ₂ ) _n Si (OCH ₃ ) ₃ (where n = 5 to 19) is particularly preferable. For the same reason, R ₁ is preferably an alkyl group having 7 to 16 carbon atoms or a perfluoroalkyl group.

  The treatment with the coupling agent is preferable, for example, in the case where the spherical composite melamine resin particles are immersed in a solution containing the coupling agent and dried, so that a uniform coating can be formed. The adhesion amount of the coupling agent is preferably in the range of 0.1 to 25% by mass with respect to the spherical composite melamine resin particles.

Further, the surface of the spherical composite melamine resin particles themselves may be treated with silicone oil or the like. A known silicone oil can be used for the treatment, and it contains a dry method such as a spray dry method in which a treatment agent or a solution containing the treatment agent is sprayed on particles suspended in the gas phase, or a treatment agent. It can be processed by a wet method in which particles are immersed in a solution and dried.
By the method described above, composite resin particles containing inorganic particles can be obtained.

  In FIG. 2, the cross section of an example of the produced composite resin particle is shown typically. In FIG. 2, 40 indicates the resin constituting the composite resin particle 22, and 50 indicates the inorganic particle. In the composite resin particles in the present invention, the inorganic particles 50 may be uniformly dispersed or non-uniformly dispersed. According to the above-described manufacturing method, the composite resin particles 22 are as shown in FIG. In addition, the inorganic particles 50 are unevenly distributed near the surface of the composite resin particles 22.

  In the present invention, it is preferable that the inorganic particles 50 are partially exposed on the surface of the composite resin particle 22 as will be described later. For this purpose, in the production of the composite resin particle 22, the inorganic particles 50 can be added in a small amount. From the viewpoint of developing 50 exposure, the inorganic particles 50 are preferably unevenly distributed in the vicinity of the surface of the composite resin particle 22 as shown in FIG.

  Here, the “uneven distribution” is a range of 10% in the depth direction from the surface to the particle size of the composite resin particles 22 and a range of 40 to 100% of the inorganic particles 50 contained in the composite resin particles 22 (several ) Exists.

  According to the manufacturing method described above, the composite resin particles 22 including the inorganic particles 50 become spherical melamine resin particles in which the colloidal silica that is the inorganic particles 50 is unevenly distributed near the particle surface. The inorganic particles 50 are embedded in the resin 40 in the vicinity of the composite resin particle surface as shown in 51 of FIG. 2, and are in a state of being exposed and fixed more than half on the particle surface as shown in 52, 53 There are those in which only a small portion as shown in FIG.

  Accordingly, the composite resin particles 22 are roughly spherical, but the inorganic particles 50 are taken into the composite resin particles 22 while maintaining the shape as described above, and a part of the inorganic particles 50 is on the surface. Since some of them are exposed, the surface is in an uneven shape when viewed microscopically.

  The matrix resin when it is formed as a resin coating layer and conventional single resin particles are not chemically linked. Therefore, when forming a composite film (making a carrier) using these, the carrier is copied. When used in a machine / printer, the resin particles easily fall off the matrix resin layer. On the other hand, the composite resin particle 22 including the inorganic particles 50 has an advantage that the surface thereof is fine and has an uneven shape, so that it is difficult to drop off from the matrix resin effectively as an anchor.

Thus, in the present invention, even when the composite resin particles 22 are dispersed in the matrix resin, the inorganic particles 50 can effectively contribute to the charging characteristics, and the anchor effect of the composite resin particles with respect to the matrix resin is effective. Therefore, the inorganic particles 50 are preferably partially exposed on the surface of the composite resin particle 22.
Here, the “partially exposed” refers to the state of the inorganic particles 50 indicated by 52 and 53 in FIG.

  The volume average particle size of the composite resin particles containing inorganic particles in the present invention is preferably in the range of 0.05 to 1 μm, more preferably in the range of 0.1 to 0.5 μm. When the volume average particle size is smaller than 0.05 μm, the dispersion in the resin coating layer is very poor. When the volume average particle size is larger than 1 μm, the resin coating layer tends to fall off, and the original function cannot be maintained.

Further, when the average thickness of the resin coating layer is 1, the volume average particle size of the composite resin particles 22 containing inorganic particles is preferably 1 or less, more preferably 0.8 or less, and still more preferably, 0.5 or less. This is because by setting the volume average particle size within this range, the dispersion of the composite resin particles in the resin coating layer tends to be uniform.
In addition, the measuring method of the average thickness of the said resin coating layer is mentioned later.

In the present invention, the number particle size distribution of the composite resin particles containing inorganic particles is desirably controlled within a certain range. Specifically, when the number average particle diameter of the composite resin particles was d _50, 1/2 × ratio of d ₅₀ below fine particles having a particle size of 20% by number or less, the 2 × d ₅₀ or more particle size It is preferable that the ratio of the fine particles to be contained is 20 number% or less.
The ratio is more preferably 15% by number or less, and further preferably 10% by number or less.

When the proportion of fine particles having a particle size of ½ × d ₅₀ or less exceeds 20% by number, the aggregation of small-diameter fine particles appears, and the uniformity of the composition of the resin coating layer decreases. Further, the contact charge imparting property to the toner becomes unstable. On the other hand, when the proportion of fine particles having a particle size of 2 × d ₅₀ or more exceeds 20% by number, deviation of the composite resin particles from the resin coating layer easily occurs, and the charge imparting property to the toner is Since it changes with use, stability is impaired.

  In the present invention, the volume average particle size, number average particle size, and particle size distribution of the fine particles are measured by, for example, a laser diffraction / scattering type particle size distribution measuring apparatus (trade name: Mastersizer 2000, manufactured by Malvern). be able to.

  Moreover, the shape of the composite resin particles containing inorganic particles in the present invention is not particularly limited, but a spherical shape as shown in FIG. 2 is preferable.

  The amount of the composite resin particles containing inorganic particles is preferably in the range of 1 to 50% by mass in the resin coating layer, more preferably in the range of 5 to 30% by mass, and still more preferably in the range of 5 to 20% by mass. It is. If the amount is less than 1% by mass, the above-described effect due to the addition of inorganic particles cannot be expressed. If the amount exceeds 50% by mass, the resin coating layer itself tends to be brittle.

  The matrix resin of the resin coating layer containing the composite resin particles containing the inorganic particles may be selected from any resin that can be used in the art as a coating resin for the carrier. The resin may be used alone or in combination of two or more.

  Specifically, polyolefin resins such as polyethylene, polypropylene; polyvinyl and polyvinylidene resins such as polystyrene, acrylic resin, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether and polyvinyl. Ketone; Vinyl chloride-vinyl acetate copolymer; Styrene-acrylic acid copolymer; Straight silicone resin composed of organosiloxane bond or its modified product; Fluororesin such as polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, poly Polyester; Polyurethane; Polycarbonate; Phenol resin; Amino resin such as urea-formaldehyde resin, Min resins, benzoguanamine resins, urea resins, polyamide resins, epoxy resins, and the like.

  In the carrier for an electrostatic latent image developer, a resin having a critical surface tension (γc) of preferably 35 mN / m or less, more preferably 30 mN / m or less is preferably used as the matrix resin. This is because the carrier resin has low energy on the surface of the carrier, and the spent on the surface can be suppressed.

  Examples of the resin having a critical surface tension of 35 mN / m or less include polystyrene (γc = 33 mN / m), polyethylene (γc = 31 mN / m), polyvinyl fluoride (γc = 28 mN / m), and polyvinylidene fluoride (γc). = 25 mN / m), polytrifluoroethylene (γc = 22 mN / m), polytetrafluoroethylene (γc = 18 mN / m), polyhexafluoropropylene (γc = 16 mN / m), and the like, Critical surfaces such as copolymers with acrylic monomers, copolymers of vinylidene fluoride and vinyl fluoride, fluoroterpolymers such as terpolymers of tetrafluoroethylene, vinylidene fluoride and non-fluorinated monomers A resin having a tension of 35 mN / m or less can be used.

  Among the above-mentioned resins, it is particularly preferable to contain a fluorine-containing resin, a polymer and / or a silicone resin exhibiting a critical surface tension of 30 mN / m or less.

Specifically, the critical surface tension can be determined as follows.
First, several types of n-alkane liquids with known surface tensions (with surface tensions in the range of 20 to 40 mN / m) were prepared, and these were used as droplets with a syringe under an environment of 20 ° C. It is dropped on the fluorine atom-containing resin surface, and the contact angle θ of each droplet with respect to the fluorine atom-containing resin surface is measured by a contact angle meter (for example, automatic contact angle meter CA-Z, manufactured by Kyowa Interface Science Co., Ltd.).

  Next, the cos θ value of the contact angle value θ is plotted against the surface tension of each liquid (Zisman plot), and the surface tension value at the point where the extrapolated line of the plot intersects the line of cos θ = 1.0. Is the critical surface tension.

  The conductive fine powder mixed in the resin coating layer is used for adjusting the conductivity of the carrier. In other words, as the resin film becomes thicker, the carrier is insulated, and it becomes difficult to work as a developing electrode during development, so the edge effect appears particularly in the black solid part, but the solid reproducibility is inferior, Has the ability to improve it.

The conductivity of the conductive fine powder itself is preferably 10 ¹⁰ Ωcm or less, more preferably 10 ⁹ Ωcm or less in terms of volume resistivity. What is necessary is just to select suitably from the fine powder which has the electroconductivity of such a range according to the kind etc. of matrix resin. Specific examples of the conductive fine powder include metals such as gold, silver and copper; carbon black; and semiconductive oxides such as titanium oxide and zinc oxide; titanium oxide, zinc oxide, barium sulfate and boric acid. Examples thereof include a surface of aluminum, potassium titanate powder or the like covered with tin oxide, carbon black, or metal. Carbon black is preferred from the standpoint of production stability, cost, and conductivity. The type of carbon black is not particularly limited and known ones can be used, and carbon black having a DBP (dibutyl phthalate) oil absorption in the range of 50 to 300 ml / g with good production stability is particularly preferred. The volume average particle diameter is preferably 0.1 μm or less, and the primary particle diameter is preferably 50 nm or less for dispersion.

  As a method for forming the resin coating layer on the surface of the carrier core material (core material), typically, a resin coating layer forming solution (a composite resin particle containing a matrix resin and inorganic particles in a solvent, conductive property) A solution containing a fine powder). Specifically, for example, a dipping method in which the powder of the carrier core material is immersed in the resin coating layer forming solution, a spray method in which the resin coating layer forming solution is sprayed on the surface of the carrier core material, and a flow of the carrier core material Fluidized bed method in which resin coating layer forming solution is sprayed in a state suspended by air, kneader coater method in which carrier core material and resin coating layer forming solution are mixed in kneader coater and solvent is removed, In the present invention, the kneader coater method is particularly preferably used.

  The core material (carrier core material) used in the electrostatic latent image developer carrier of the present invention is not particularly limited, and is a magnetic metal such as iron, steel, nickel and cobalt, or a magnetic oxidation such as ferrite and magnetite. From the viewpoint of using the magnetic brush method, a magnetic carrier is desirable. The volume average particle diameter of the carrier core material is preferably in the range of 10 μm to 150 μm, more preferably in the range of 30 μm to 100 μm.

  The solvent used in the resin coating layer forming solution is not particularly limited as long as it dissolves the matrix resin. For example, aromatic hydrocarbons such as toluene and xylene, and ketones such as acetone and methyl ethyl ketone. , Ethers such as tetrahydrofuran and dioxane can be used.

  On the other hand, since the composite resin particles containing inorganic particles are preferably already in the form of fine particles in a solvent, it is preferable that the composite resin particles are not substantially soluble in the solvent (solvent insoluble). As a result, the composite resin particles do not aggregate in the resin coating layer and maintain the form of primary particles.

  If the composite resin particles containing inorganic particles are uniformly dispersed in the solvent, the composite resin particles are evenly dispersed in the formed resin coating layer. Therefore, it is preferable to prepare a resin coating layer forming solution as such. . Such uniform dispersion can be achieved very easily because it is a solution. For example, it is sufficient to stir the entire solution.

  Thus, by using composite resin particles that are insoluble in matrix resin and solvent, it is possible to select both materials appropriately. With one of them, it is possible to provide stable chargeability, mechanical strength, and prevention of spent. And the rest can be improved. For example, the resin particles can improve the ability to impart stable chargeability and mechanical strength, and the matrix resin can exhibit a sufficient anti-spent function. In addition, the inorganic particles in the present invention can be used as resin particles. By using the composite resin particles that contain, it is possible to stabilize the charge imparting characteristics sufficiently against environmental changes such as humidity and temperature, and to stabilize the resin for a longer period because it can suppress the resin particles from falling off the resin coating layer. it can.

  Moreover, in the present invention, the composite resin particles containing inorganic particles can be uniformly dispersed in the matrix resin, which is suitable for stably exhibiting the ability to impart chargeability to the toner and the function of preventing spent. Yes. In addition, this uniform dispersion can maintain the same surface composition as when the resin coating layer is not used even when the resin coating layer is worn from the surface for a long period of time. It is possible to maintain a good spent prevention function.

  In addition, since conductive fine powder is contained in the resin coating layer, the electrical performance of the carrier can be controlled to be more desirable.

The average film thickness (average thickness) of the resin coating layer formed as described above is preferably in the range of 0.1 to 10 μm, more preferably in the range of 0.2 to 3 μm. The average thickness of the resin coating layer is ρ _D as the specific gravity of the carrier core material, _D as the volume average particle diameter of the carrier core material, ρ _{C as} the average specific gravity of the resin including the coated composite resin particles, and the total coating amount of the resin. When W _C is used, it is easily calculated by the following formula.

Average film thickness (l) = [amount of coating resin per carrier (including composite resin particles including inorganic particles) / surface area per carrier] / average specific gravity of coating resin
= [4 / 3π · (D / 2) ³ · ρ _D · W _C ] / [4π (D / 2) ³ ] ÷ ρ _C
= (1/6) · (D · ρD ・ W _C / ρ _C )

In the present invention, the carrier resistance is preferably controlled in the range of 1 × 10 ⁸ to 1 × 10 ¹⁴ Ωcm, more preferably in the range of 1 × 10 ⁸ to 1 × 10 ¹³ Ωcm. More preferably, it is in the range of 10 ⁸ to 1 × 10 ¹² Ωcm.

Since the carrier resistance becomes a high resistance exceeding 1 × 10 ¹⁴ Ωcm and it becomes difficult to work as a developing electrode during development, the solid reproducibility is deteriorated, for example, an edge effect appears in a solid image portion. On the other hand, since it has a low resistance of less than 1 × 10 ⁸ Ωcm, when the toner concentration in the developer decreases, charges are injected from the developing roll into the carrier, and the carrier itself is easily developed.

The carrier resistance (Ω · cm) was measured as follows. The measurement environment was a temperature of 20 ° C. and a humidity of 50% RH.
The carrier to be measured is placed flat on the surface of a circular jig having a 20 cm ² electrode plate so as to have a thickness of about 1 to 3 mm to form a carrier layer. A 20 cm ² electrode plate similar to the above is placed on this and the carrier layer is sandwiched. In order to eliminate the gap between the carriers, the thickness (mm) of the carrier layer is measured after a load of 4 kg is applied on the electrode plate placed on the carrier layer. Both electrodes above and below the carrier layer are connected to an electrometer and a high-voltage power generator. A high voltage is applied to both electrodes so that the electric field is 10 ^3.8 V / cm, and the current value (A) flowing at this time is read to calculate the carrier resistance (Ω · cm). The calculation formula of the carrier resistance (Ω · cm) is as shown in the following formula (1).
R = E × 20 / (I−I ₀ ) / L (1)
In the above formula, R is the carrier resistance (Ω · cm), E is the applied voltage (V), I is the current value (A), I ₀ is the current value (A) at an applied voltage of 0 V, and L is the thickness of the carrier layer ( mm) respectively. A coefficient of 20 represents the area (cm ² ) of the electrode plate.

<Electrostatic latent image developer>
The carrier for electrostatic latent image developer of the present invention is used together with any kind of granular toner to become an electrostatic latent image developer.

  The toner is roughly classified into a dry method using a conventional melt-kneading pulverization method and a wet method in which the toner is granulated in a liquid. Recently, wet methods are being evaluated from the viewpoints of reducing the toner diameter, sharpening the particle size distribution, freedom of shape control (more easily spheroidizing), and reducing the energy cost of production. However, since the wet method granulates toner particles in a liquid, hydrophilic groups are likely to remain on the toner surface, causing moisture absorption under high humidity and tending to deteriorate charging characteristics. For this reason, the conventional developer containing the toner obtained by the wet method has a defect that charging characteristics deteriorate under high humidity.

  In addition to controlling the molecular weight of the binder resin, the glass transition temperature, etc., in order to improve such properties as storage stability (blocking resistance), transportability, developability, transferability, and chargeability of the toner. Organic / inorganic fine particles called external additives are added to the toner particle surfaces.

  Examples of the inorganic fine particles include hydrophobic fine powders typified by hydrophobic silica, silica fine particles to which alumina or titania is added, and inorganic fine particles having a hydrophobization degree distribution. There is a problem that both of the characteristics and the charge maintaining characteristics cannot be satisfied.

  As the electrostatic latent image developer of the present invention, both the toner by the dry method and the toner by the wet method can be applied. As described above, the carrier for the electrostatic latent image developer of the present invention is Since the electrostatic latent image developer of the present invention has a stable charge-imparting ability even with respect to changes in humidity, the effect can be exerted more when toner produced by a wet method is used.

The toner in the present invention is spherical from the viewpoint of obtaining a high quality image by improving the toner transportability, charging uniformity, transferability, etc. in addition to the charging stability by the electrostatic latent image developer carrier of the present invention. It is preferable that the shape factor SF1 (ML ² / A: ML represents the maximum length of the toner and A represents the projected area of the toner) is in the range of 100 to 140. SF1 is more preferably in the range of 105 to 135, and still more preferably in the range of 105 to 130.

The toner shape factor SF1 is obtained by taking an optical microscope image of the toner dispersed on the surface of the slide glass into a Luzex image analyzer through a video camera, and obtaining the maximum length and projected area of 50 or more toner particles. ) To calculate ML ² / A and obtain the average value.
ML ² / A = (maximum length) ² × π × 100 / (projected area × 4) Expression (2)

  The toner production method in the present invention includes a dry method using a pulverization classification method and a wet method in which particles are produced in a liquid. Although there is no limitation in the present invention, a wet method is used to produce the spherical toner. The law is suitable.

  The wet method includes a resin fine particle dispersion obtained by emulsion polymerization of a polymerizable monomer of a binder resin, a colorant dispersion, a release agent dispersion, and a dispersion such as a charge control agent as necessary. Emulsion polymerization aggregation method in which toner particles are obtained by mixing by heating and forming aggregated particles to obtain toner particles; a polymerizable monomer for obtaining a binder resin, a colorant, a release agent, and if necessary Suspension polymerization method in which a solution such as a charge control agent is suspended in an aqueous solvent and polymerized to obtain toner particles; a binder resin, a colorant, a release agent, and a solution such as a charge control agent as required There is a solution suspension method in which a suspension is suspended in an aqueous solvent and granulated. Among these, the emulsion polymerization aggregation method is optimal.

  In the emulsion polymerization aggregation method, a resin particle dispersion in which resin particles having a particle diameter of 1 μm or less are dispersed and a colorant dispersion in which a colorant is dispersed are mixed to aggregate the resin particles and the colorant into a toner particle diameter. A step (hereinafter sometimes referred to as “aggregation step”), and a step of heating to a temperature equal to or higher than the glass transition point of the resin to fuse the aggregate to form colored toner particles (hereinafter referred to as “fusion step”). Included).

  In the aggregation step, the resin particle dispersion mixed with each other, the colorant dispersion, and, if necessary, the resin particles in the release agent dispersion aggregate to form aggregated particles. The agglomerated particles are formed by heteroaggregation or the like. For the purpose of stabilizing the agglomerated particles and controlling the particle size / size distribution, the ionic surfactant having a polarity different from that of the agglomerated particles, or a monovalent or higher monovalent metal salt, It is formed by adding a compound having a charge.

  In the fusion step, the resin in the aggregated particles melts at a temperature condition equal to or higher than the glass transition point, and the aggregated particles change from an indeterminate shape to a spherical shape. At this time, the shape factor SF1 of the aggregated particles is 150 or more, and becomes smaller as it becomes spherical, and the shape factor is controlled by stopping the heating of the toner when the desired shape factor is reached. is there. Thereafter, the agglomerates are separated from the aqueous medium, and washed and dried as necessary to form toner particles.

  In addition, the suspension polymerization method can also be preferably used as a method for producing the toner used in the present invention. In the suspension polymerization method, colorant particles, release agent particles and the like are suspended in an aqueous medium to which a dispersion stabilizer and the like are added together with a polymerizable monomer as required, and a desired particle size and particle size distribution are obtained. Then, the polymerizable monomer is polymerized by means such as heating, and after polymerization, the polymer is separated from the aqueous medium, washed and dried as necessary to form toner particles.

  Examples of the binder resin used in the toner in the present invention include styrenes such as styrene and chlorostyrene; monoolefins such as ethylene, propylene, butylene, and isoprene; vinyls such as vinyl acetate, vinyl propionate, vinyl benzoate, and vinyl butyrate. Esters; (meth) acrylic acid, vinyl acetic acid, allyl acetic acid, unsaturated carboxylic acids such as 10-undecenoic acid, styrene derivatives having a carboxyl group such as carboxyl styrene; methyl acrylate, ethyl acrylate, butyl acrylate, Α-methylene aliphatic monocarboxylic acid esters such as dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate; vinyl methyl ether, vinyl ethyl ether, vinyl Examples of vinyl ethers such as rubutyl ether; homopolymers and copolymers of vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, vinyl isopropenyl ketone, and the like. Particularly typical binder resins include polystyrene. Styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyethylene, polypropylene and the like. it can. Further examples include polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin wax and the like.

  Examples of the colorant used in the toner in the present invention include magnetic powders such as magnetite and ferrite, carbon black, aniline blue, caryl blue, chrome yellow, ultramarine blue, dupont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, and malachite. Green oxalate, lamp black, rose bengal, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 57: 1, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 128, C.I. I. Pigment yellow 151, C.I. I. Pigment yellow 155, C.I. I. Pigment yellow 173, C.I. I. Pigment yellow 180, C.I. I. Pigment yellow 185, C.I. I. Pigment blue 15: 1, C.I. I. Pigment Blue 15: 3 can be exemplified as a representative one.

  Typical examples of the release agent used in the toner in the present invention include low molecular weight polyethylene, low molecular weight polypropylene, Fischer-Tropsch wax, montan wax, carnauba wax, rice wax, and candelilla wax. A well-known thing can be used.

  In the toner used in the present invention, for example, the interface at the time of dispersion in the suspension polymerization method and the dispersion stability of the resin particle dispersion, the colorant dispersion, and the release agent dispersion in the emulsion polymerization aggregation method are used. An activator can be used.

  Examples of the surfactant include sulfate surfactants, sulfonates, phosphates, soaps, and the like; amine surfactants, quaternary ammonium salt and other cationic surfactants; polyethylene glycol And nonionic surfactants such as polyphenols, alkylphenol ethylene oxide adducts, and polyhydric alcohols. Among these, an ionic surfactant is preferable, and an anionic surfactant and a cationic surfactant are more preferable.

  In the toner of the present invention, an anionic surfactant generally has a strong dispersing power and is excellent in dispersing resin particles and colorants. Therefore, a cationic surfactant is used as a surfactant for dispersing a release agent. It is advantageous to use a surfactant.

  The nonionic surfactant is preferably used in combination with the anionic surfactant or the cationic surfactant. The said surfactant may be used individually by 1 type, and may be used in combination of 2 or more type.

  In addition, as the dispersion stabilizer used in the suspension polymerization method, a slightly water-soluble and hydrophilic inorganic fine powder can be used. Examples of the inorganic fine powder that can be used include silica, alumina, titania, calcium carbonate, magnesium carbonate, tricalcium phosphate (hydroxyapatite), clay, diatomaceous earth, bentonite and the like. Among these, calcium carbonate, tricalcium phosphate, and the like are preferable from the viewpoints of easy particle size formation and easy removal.

  Also, a room temperature solid aqueous polymer or the like can be used as a dispersion stabilizer. Specifically, cellulose compounds such as carboxymethyl cellulose and hydroxypropyl cellulose, polyvinyl alcohol, gelatin, starch, gum arabic and the like can be used.

  In the toner production according to the present invention, when the emulsion polymerization aggregation method is used, aggregation can be generated by pH change in the aggregation step to adjust particles. At the same time, a flocculant may be added as a method for stably and rapidly agglomerating particles or obtaining agglomerated particles having a narrower particle size distribution.

  As the flocculant, a compound having a monovalent or higher charge is preferable, and specific examples of the compound having a monovalent or higher charge include water-soluble surfactants such as the above-mentioned ionic surfactants and nonionic surfactants. Agents; acids such as hydrochloric acid, sulfuric acid, nitric acid, acetic acid, oxalic acid; metal salts of inorganic acids such as magnesium chloride, sodium chloride, aluminum sulfate, calcium sulfate, ammonium sulfate, aluminum nitrate, silver nitrate, copper sulfate, sodium carbonate; acetic acid Aliphatic acids such as sodium, potassium formate, sodium oxalate, sodium phthalate, potassium salicylate; metal salts of aromatic acids; metal salts of phenols such as sodium phenolate; metal salts of amino acids; triethanolamine hydrochloride; Inorganic acid salts of aliphatic and aromatic amines such as aniline hydrochloride;

In consideration of stability of the aggregated particles, stability of the aggregating agent with respect to heat and time, and removal during washing, the metal salt of the inorganic acid is preferable in terms of performance and use.
Specifically, metal salts of inorganic acids such as magnesium chloride, sodium chloride, aluminum sulfate, calcium sulfate, ammonium sulfate, aluminum nitrate, silver nitrate, copper sulfate, and sodium carbonate.

  The amount of these flocculants to be added varies depending on the valence of the charge, but they are all small, in the case of monovalent, about 3% by mass or less, in the case of divalent, about 1% by mass, in the case of trivalent Is about 0.5 mass% or less. In the electrostatic latent image developer of the present invention, from the viewpoint of stable charging performance (environmental stability and maintainability), the amount of the flocculant is preferably small, and a compound having a high valence is preferable.

  In addition, a charge control agent may be added to the toner in the present invention as necessary. Known charge control agents can be used, but azo metal complex compounds, metal complex compounds of salicylic acid, and resin type charge control agents containing polar groups can be used. It is preferable to use a material that is difficult to dissolve in water in terms of controlling ionic strength and reducing wastewater contamination. The toner in the present invention may be either a magnetic toner containing a magnetic material or a non-magnetic toner containing no magnetic material.

  The electrostatic latent image developer of the present invention is obtained by mixing the above-described carrier for electrostatic latent image developer of the present invention and the above toner, and the mixing ratio thereof is for the electrostatic latent image developer. The toner is preferably mixed and adjusted in the range of 3 to 20 parts by mass with respect to 100 parts by mass of the carrier.

<Image Forming Method, Image Forming Apparatus>
The image forming method of the present invention includes a developing step of developing an electrostatic latent image on the surface of the electrostatic latent image carrier using at least a developer layer including a toner and a carrier formed on the surface of the developer carrier. In the image forming method including the above, the carrier for an electrostatic latent image developer of the present invention described above is used as the carrier.

  The developing step refers to the electrostatic latent image on the surface of the latent image carrier by bringing the developer carrier on which the developer layer containing at least toner is formed on the surface of the latent image carrier. In this step, toner particles are adhered to the surface of the latent electrostatic image bearing member to form a toner image. The development method can be performed using a known method, and examples of the development method using the two-component developer used in the present invention include a cascade method and a magnetic brush method. The development may be a so-called regular development method or a reversal development method, but it is preferable to use a reversal development method. The image forming method of the present invention is not particularly limited with respect to the developing method.

In the present invention, it suffices that at least the development step is included, and in addition, an electrostatic latent image forming step, a transfer step, a fixing step, and the like may be included.
In the image forming method as described above, by using the electrostatic latent image developer of the present invention as a developer, stable image formation can be performed over a long period of time against environmental changes.

FIG. 3 schematically shows an example of an image forming apparatus used in the image forming method of the present invention.
In the image forming apparatus shown in FIG. 3, first, the reflected light irradiated on the document 802 from the illumination 801 is read by the color CCD 803, and color-separated into three colors Y, M, and C by the image processing apparatus 804, and image processing is performed. In addition, for each color, a signal obtained by changing the angle of the nearest neighbor pixel is output as an optical signal from the semiconductor laser 805 in order for each color. The optical signal is exposed to a photosensitive member (electrostatic latent image carrier) 808 charged in advance by a charger 807 through an optical system 806 to produce an electrostatic latent image in which the image portion has a low potential.

  Next, developers A, B, C, D (electrostatic latent image developer) composed of charged colored toner (yellow, magenta, cyan, black) and the carrier of the present invention are supplied to developing units 809 to 812 (developing means). ) And applying a developing bias, the colored toner is developed into an electrostatic latent image on the photoreceptor by electrostatic force.

  The developed toner is transferred to the paper 814 electrostatically attracted to the transfer drum 813 one by one by the electric field applied by the transfer corotron 815. This is repeated three times in the order of Y, M, and C, and a color toner image superimposed on three colors on the paper 814 is obtained. Thereafter, the image was fixed by heating with a fixing device 816 to obtain a color image.

Hereinafter, the present invention will be specifically described by way of examples.
First, composite resin particles, carriers, and toners used in each example and comparative example will be described.
(Production of composite resin particles containing inorganic particles)
-Composite resin particle 1-
In a 2 L reaction flask equipped with a stirrer, reflux condenser and thermometer, 50.0 parts by mass of melamine, 96.5 parts by mass of formalin 96.5 parts by mass, aqueous silica sol (manufactured by Nissan Chemical Industries, Ltd., trade name: Snowtex) S, SiO ₂ concentration: 30.5% by mass, pH: 10.0, average particle size: 7.9 nm) 20.7 parts by mass and 720 parts by mass of water were charged, and the pH was adjusted to 8. with 25% by mass ammonia water. Adjusted to 7. Thereafter, the temperature of the mixture was increased while stirring, the temperature was kept at 70 ° C., and the mixture was reacted for 30 minutes to prepare an aqueous solution of an initial condensate of melamine resin.

  Next, while maintaining the temperature at 70 ° C., a 10% by mass aqueous solution of dodecylbenzenesulfonic acid was added to the obtained aqueous solution of the initial condensate to adjust the pH to 7.0. About 20 minutes later, the reaction system became cloudy, and cured melamine resin particles (composite resin particles) containing colloidal silica (inorganic particles) were precipitated. Thereafter, the temperature was raised to 90 ° C. and the curing reaction was continued for 3 hours. After cooling, the resulting reaction solution was filtered and dried to obtain white composite resin particles 1.

The volume average particle diameter of the composite resin particle 1 was 0.3 μm as measured by a laser diffraction / scattering particle size distribution analyzer (trade name: Mastersizer 2000, manufactured by Malvern). The number average particle diameter d ₅₀ is 0.27 μm, the proportion of fine particles having a particle size of 1/2 × d ₅₀ or less is 5%, and the proportion of fine particles having a particle size of 2 × d ₅₀ or more is 15%. Number%.

  The cured melamine composite resin particles (composite resin particles 1) are observed as they are with a scanning electron microscope (SEM), and in the state of slice pieces, transmission electron microscope-energy dispersive X-ray analysis (TEM) -EDX), the composite resin particle 1 is spherical, and the colloidal silica is unevenly distributed in the vicinity of the particle surface (about 80% of the colloidal silica exists in the range of 10% in the depth direction of the particle diameter). It was confirmed that the colloidal silica was partially exposed on the surface of the composite resin particles.

-Composite resin particle 2-
In a 2 L reaction flask equipped with a stirrer, reflux condenser and thermometer, 50.0 parts by mass of melamine, 96.5 parts by mass of formalin 96.5 parts by mass, aqueous silica sol (manufactured by Nissan Chemical Industries, Ltd., trade name: Snowtex) S, SiO ₂ concentration: 30.5% by mass, pH: 10.0, average particle size: 7.9 nm) 35.7 parts by mass and water 920 parts by mass were charged, and pH was adjusted to 8. with 25% by mass ammonia water. Adjusted to 5. Thereafter, the temperature of the mixture was increased while stirring, the temperature was kept at 70 ° C., and the mixture was reacted for 30 minutes to prepare an aqueous solution of an initial condensate of melamine resin.

  Next, while maintaining the temperature at 70 ° C., a 10% by mass aqueous solution of dodecylbenzenesulfonic acid was added to the aqueous solution of the obtained initial condensate to adjust the pH to 7.0. About 25 minutes later, the reaction system became cloudy, and cured melamine resin particles (composite resin particles) containing colloidal silica (inorganic particles) were precipitated. Thereafter, the temperature was raised to 90 ° C. and the curing reaction was continued for 3 hours. After cooling, the resulting reaction solution was filtered and dried to obtain white composite resin particles 2.

The volume average particle diameter of the composite resin particle 2 was 0.15 μm as measured with a laser diffraction / scattering particle size distribution analyzer (trade name: Mastersizer 2000, manufactured by Malvern). The number average particle diameter d ₅₀ is 0.13 μm, the proportion of fine particles having a particle size of 1/2 × d ₅₀ or less is 10%, and the proportion of fine particles having a particle size of 2 × d ₅₀ or more is 7%. Number%.

  The cured melamine composite resin particles (composite resin particles 2) are observed as they are with a scanning electron microscope (SEM), and in the state of slices, transmission electron microscope-energy dispersive X-ray analysis (TEM) -EDX), the composite resin particle 2 is spherical, and the colloidal silica is unevenly distributed near the particle surface (the colloidal silica is about 75% in the range of 10% in the depth direction of the particle diameter). It was confirmed that the colloidal silica was partially exposed on the surface of the composite resin particles.

(Creation of carrier)
-Carrier A-
Ferrite particles (volume average particle size: 50 μm) 100 parts by mass Toluene 14 parts by mass Styrene-methacrylate copolymer (critical surface tension: 35 mN / m) 1.5 parts by mass Carbon black (average particle size: 25 nm, DBP oil absorption: 71 ml / g, volume resistivity: 10 ⁰ Ωcm or less, trade name: R330R, manufactured by Cabot Corporation) 0.15 parts by mass Composite resin particles 1 0.3 parts by mass

The above components except for the ferrite particles were mixed and dispersed with a stirrer for 10 minutes to prepare a resin coating layer forming solution. Next, the resin coating layer forming solution and the ferrite particles were put in a vacuum degassing type kneader and stirred at a temperature of 60 ° C. for 30 minutes, and then the pressure was reduced and toluene was distilled off to form a resin coating layer. Carrier A was obtained (however, the styrene-methacrylate copolymer, which is a matrix resin, was diluted with toluene and the carbon black was previously dispersed in a sand mill). The average thickness of the resin coating layer was 0.7 μm, and the volume resistivity of the carrier was 10 ⁸ Ωcm.

-Carrier B-
Ferrite particles (volume average particle size: 50 μm) 100 parts by mass Toluene 14 parts by mass Styrene-methacrylate copolymer (critical surface tension: 35 mN / m) 1.0 part by mass Perfluoroacrylate copolymer (critical surface Tension: 24 mN / m) 0.8 parts by mass Conductive powder (BaSO ₄ , average particle size: 0.2 μm, volume resistivity: 5 to 30 Ωcm, trade name: Pastorran Type-IV, manufactured by Mitsui Kinzoku) 4 parts by mass-Composite resin particle 1 0.2 parts by mass

The above components except for the ferrite particles were dispersed with a homomixer for 10 minutes to prepare a resin coating layer forming solution. Further, this resin coating layer forming solution and ferrite particles are put in a vacuum degassing type kneader and stirred at a temperature of 60 ° C. for 30 minutes, and then the pressure is reduced to distill off toluene to form a resin coating layer. Carrier B was obtained (however, the styrene-methacrylate copolymer and perfluoroacrylate copolymer, which were matrix resins, were diluted in toluene, and the conductive powder was previously dispersed in a sand mill). The average thickness of the resin coating layer was 0.6 μm, and the volume resistivity of the carrier was 10 ¹¹ Ωcm.

-Carrier C-
Ferrite particles (volume average particle diameter: 45 μm) 100 parts by mass Toluene 14 parts by mass Perfluoroacrylate copolymer (critical surface tension: 24 mN / m) 1.7 parts by mass Conductive powder (SnO ₂ , average particle diameter) : 20 nm, volume resistivity: 10 ⁶ to 10 ⁸ Ωcm, trade name: S-1, manufactured by Mitsubishi Materials Corporation) 0.6 parts by mass Composite resin particle 2 0.3 parts by mass

The above components except for ferrite particles were dispersed with a stirrer for 10 minutes to prepare a resin coating layer forming solution. Next, the resin coating layer forming solution and ferrite particles are placed in a vacuum degassing type kneader and stirred at a temperature of 60 ° C. for 30 minutes, and then the pressure is reduced to distill off toluene to form a resin coating layer. Thus, carrier C was obtained (however, a perfluoroacrylate copolymer as a matrix resin was diluted in toluene and tin oxide was previously dispersed in a sand mill). The average thickness of the resin coating layer was 0.6 μm, and the volume resistivity of the carrier was 10 ¹² Ωcm.

-Carrier D-
Ferrite particles (volume average particle size: 45 μm) 100 parts by mass Toluene 14 parts by mass Perfluoroacrylate copolymer (critical surface tension: 24 mN / m) 1.6 parts by mass Carbon black (average particle size: 30 nm, DBP oil absorption: 174 ml / g, a volume resistivity: 10 ⁰ [Omega] cm or less, trade name: VXC-7, manufactured by Cabot Corporation) 0.12 parts by mass composite resin particles 2 0.3 part by weight

The above components except for the ferrite particles were dispersed with a stirrer for 10 minutes to prepare a resin coating layer forming solution. Further, this resin coating layer forming solution and ferrite particles are put in a vacuum degassing type kneader and stirred at a temperature of 60 ° C. for 30 minutes, and then the pressure is reduced to distill off toluene to form a resin coating layer. Carrier D was obtained (however, a perfluoroacrylate copolymer, which is a matrix resin, was diluted in toluene, and carbon black was previously dispersed in a sand mill). The average thickness of the resin coating layer was 0.6 μm, and the volume resistivity of the carrier was 10 ¹⁰ Ωcm.

-Carrier E-
Carrier E was obtained in the same manner as carrier A except that composite resin particle 1 was not used. The average thickness of the resin coating layer was 0.6 μm, and the volume resistivity of the carrier was 10 ⁸ Ωcm.

-Carrier F-
In Carrier D, Carrier F was obtained in the same manner as Carrier D except that carbon black was not used. The average thickness of the resin coating layer was 0.6 μm, and the volume resistivity of the carrier was 10 ¹⁶ <Ωcm.

-Carrier G-
Ferrite particles (average particle size: 45 μm) 100 parts by mass Toluene 14 parts by mass Perfluoroacrylate copolymer (critical surface tension: 24 mN / m) 0.8 parts by mass Copolymerization of methacrylate and dimethylaminoethyl methacrylate Combined (critical surface tension: 42 mN / m) 1.5 parts by mass

The above components except for the ferrite particles were dispersed with a stirrer for 10 minutes to prepare a resin coating layer forming solution. Next, the resin coating layer forming solution and ferrite particles are placed in a vacuum degassing kneader and stirred for 30 minutes at a temperature of 60 ° C., and then the pressure is reduced to distill off the toluene to form a resin coating layer. Carrier G was obtained. The average thickness of the resin coating layer was 0.8 μm, and the volume resistivity of the carrier was 10 ¹⁶ <Ωcm.

-Carrier H-
Ferrite particles (average particle size: 45 μm) 100 parts by mass Toluene 14 parts by mass Perfluoroacrylate copolymer (critical surface tension: 24 mN / m) 1.6 parts by mass Carbon black (trade name: VXC-72, 0.12 parts by mass of non-crosslinked melamine resin 0.3 parts by mass

The above components except for the ferrite particles were dispersed with a stirrer for 10 minutes to prepare a resin coating layer forming solution. Next, this resin coating layer forming solution and ferrite particles were put in a vacuum degassing type kneader and stirred at a temperature of 60 ° C. for 30 minutes, and then the pressure was reduced to distill off toluene. Thereafter, a resin coating layer containing a melamine resin that was further thermally crosslinked by stirring for 60 minutes at a temperature of 150 ° C. was formed to obtain a carrier H (however, the perfluoroacrylate copolymer as a matrix resin was diluted in toluene). Carbon black was previously dispersed with a sand mill). The average thickness of the resin coating layer was 0.7 μm, and the volume resistivity of the carrier was 10 ¹¹ Ωcm. Moreover, this resin coating layer was two continuous layers.

-Carrier I-
In Example 1, Carrier I was obtained in the same manner as in Example 1 except that the composite resin particles 1 were changed to crosslinked melamine particles (volume average particle size: 0.3 μm, toluene insoluble). The average thickness of the resin coating layer was 0.7 μm, and the volume resistivity of the carrier was 10 ⁹ Ωcm.

(Production of toner)
-Toner A-
Linear polyester resin (linear polyester obtained from terephthalic acid / bisphenol A ethylene oxide adduct / cyclohexanedimethanol, Tg (glass transition temperature): 62 ° C., Mn (number average molecular weight): 4,000, Mw (Weight average molecular weight): 35,000, acid value: 12, hydroxyl value: 25) 100 parts by mass-Magenta pigment (CI Pigment Red 57) 3 parts by mass

  The mixture was kneaded with an extruder, pulverized with a jet mill, and classified with an air classifier to obtain magenta toner particles having a volume average particle diameter D50 of 7.5 μm and a shape factor SF1 of 138.5. To the magenta toner particles, 0.4% by mass of silica (trade name: R972, manufactured by Nippon Aerosil Co., Ltd.) and 0.7% by mass of titania (trade name: T805, manufactured by Nippon Aerosil Co., Ltd.) were added and mixed with a Henschel mixer to obtain magenta toner ( Toner A) was obtained.

The shape index SF1 of the toner means a value calculated by the following formula (2), and ML ² / A is 100 in the case of a true sphere.
ML ² / A = (maximum length) ² × π × 100 / (projected area × 4) Expression (2)
As a specific method for obtaining an average shape index, a toner image is taken from an optical microscope into an image analyzer (LUZEX III, manufactured by Nireco Corporation), an equivalent circle diameter is measured, and the maximum length and projected area are calculated. The ML ² / A value of the above formula was determined for each particle.

-Toner B-
a. Preparation of resin dispersion-328 parts by mass of styrene-72 parts by mass of n-butyl acrylate-8 parts by mass of acrylic acid-8 parts by mass of dodecanethiol-1 part by mass of divinylbenzene (manufactured by Wako Pure Chemical)

  6 parts by mass of nonionic surfactant (Nonipol 400, manufactured by Sanyo Chemical Co., Ltd.) and anionic surfactant (Neogen SC, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) were prepared by mixing and dissolving the above components. ) 10 parts by mass dissolved in 550 parts by mass of ion-exchanged water was emulsified and dispersed in a flask, and while slowly mixing for 10 minutes, 50 parts by mass of ion-exchanged water in which 4 parts by mass of ammonium persulfate had been dissolved was added thereto. After carrying out nitrogen substitution, the inside of the flask was stirred and heated in an oil bath until the contents reached 70 ° C., and emulsion polymerization was continued for 5 hours. As a result, a resin dispersion was obtained in which resin particles having an average particle diameter of 155 nm, Tg of 54 ° C., and weight average molecular weight Mw of 33000 were dispersed.

b. Preparation of colorant dispersion-70 parts by mass of Magenta pigment (R122)-5 parts by mass of an anionic surfactant (Neogen SC: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)-200 parts by mass of ion-exchanged water

  A colorant dispersant in which the above components are mixed, dissolved, and dispersed for 10 minutes using a homogenizer (Ultra Turrax T50, manufactured by IKA) to disperse colorant (magenta) particles having an average particle diameter of 250 nm. Was prepared.

c. Release agent dispersion liquid 50 parts by mass of paraffin wax (HNP0190, Nippon Seiwa Co., Ltd., melting point: 85 ° C.) 5 parts by mass of anionic surfactant (Neogen SC, Daiichi Kogyo Seiyaku Co., Ltd.)

  The above components were dispersed in a round stainless steel flask using a homogenizer (Ultra Turrax T50, manufactured by IKA) for 10 minutes, and then dispersed with a pressure discharge type homogenizer. A release agent dispersion liquid in which the mold agent particles were dispersed was prepared.

d. Preparation of agglomerated particles-200 parts by mass of resin dispersion-200 parts by mass of colorant dispersion-40 parts by mass of release agent dispersion-1.5 parts by mass of aluminum sulfate

  The above components were mixed and dispersed in a round stainless steel flask using a homogenizer (Ultra Turrax T50, manufactured by IKA), and then heated to 50 ° C. while stirring the flask in an oil bath for heating. . After maintaining at 50 ° C. for 20 minutes, it was confirmed with an optical microscope that it was confirmed that aggregated particles having an average particle diameter of about 4.7 μm were formed. Further, 60 parts by mass of the resin dispersion was gently added to the dispersion. The temperature of the heating oil bath was raised to 52 ° C. and held for 30 minutes. When observed with an optical microscope, it was confirmed that adhered particles having an average particle diameter of about 5.3 μm (particles having resin particles adhered to the surface of aggregated particles) were formed.

e. Preparation of Toner A 0.1 mol / L sodium hydroxide aqueous solution was added to the particle dispersion to adjust the pH to 6.5. Thereafter, the mixture was heated to 95 ° C. with stirring, further adjusted to pH 4.5 with a 0.1 mol / L aqueous nitric acid solution, and maintained for 4 hours. After cooling, the particles were filtered, washed thoroughly with ion exchange water, and then dried to obtain toner particles (magenta) having a shape factor SF1 of 133.5 and a volume average particle diameter D50 of 6.0 μm.

  0.4% by mass of silica (trade name: R972, manufactured by Nippon Aerosil Co., Ltd.) and 0.7% by mass of titania (trade name: T805, manufactured by Nippon Aerosil Co., Ltd.) are added to the toner particles, and the mixture is mixed with a Henschel mixer. A magenta toner (toner B) was obtained.

(Examples 1-4, Comparative Examples 1-5)
Nine types of developers were prepared by mixing 100 parts by mass of each of the carriers A to I with 6 parts by mass of the toner A. The respective developers are referred to as electrostatic latent image developers 1 to 9 (electrostatic latent image developers 5 to 9 are comparative developers).
These developers were subjected to image formation and evaluation described later.

(Examples 5 to 8, Comparative Example 6)
100 parts by mass of each of the carriers A to D and I was mixed with 6 parts by mass of the toner B (magenta) to prepare five types of developers. The developers are electrostatic latent image developers 10 to 14 (electrostatic latent image developer 14 is a developer for comparison).
These developers were similarly subjected to the following image formation and evaluation.

(Image formation and its evaluation)
For the developers 1 to 14, using an electrophotographic copying machine (trade name: DocuCentreColor 500, manufactured by Fuji Xerox Co., Ltd.), high temperature and high humidity (28 ° C., 85% RH), and low temperature and low humidity (10 ° C., Each of the 10,000 copy tests was performed under an environment of 30% RH).

  The evaluation was made based on the toner charge amount and image quality (image density, fogging) after 3000 sheets and 10,000 sheets in each environment. The evaluation methods and evaluation criteria for each evaluation are shown below.

-Toner charge amount-
The toner charge amount in the actual machine evaluation is about 0.3g of developer on the mag sleeve in the developing device in each environment and the number of copies, and blow-off with Toshiba TB200 under conditions of 25 ° C and 55% RH. Measured by the method.

-Image density-
The optical density of the solid image portion was measured with an X-rite densitometer.

-Fogging-
The white background of the image was visually observed and judged according to the following criteria.
○: No fogging.
X: Some fogging.
XX: fog is conspicuous.
With respect to the above results, developers 1 to 9 are summarized in Table 1, and developers 10 to 14 are summarized in Table 2.

  In the developers 1 to 4 and the developers 10 to 13 using the carrier of the embodiment, the toner charge amount is stable up to 10000 sheets through a high temperature and high humidity and low temperature and low humidity environment. There were no fluctuations or smudges, and a stable image without edge effects was obtained.

  On the other hand, in the developer 5 using the carrier of Comparative Example 1, the charge amount gradually decreased with the number of copies, and background fogging occurred, and toner contamination was observed in the machine.

  In the case of developers 6 and 7 using the carriers of Comparative Examples 2 and 3, the edge effect was clearly seen. Further, in the case of the developer 8 using the carrier of Comparative Example 4, the variation of the charge amount in the copy test is large, and the image density may be less than 1.3. The developer using the carrier of Comparative Example 5 In the case of 9, the environmental fluctuation of the charge amount was large, and there was no problem in the high temperature and high humidity environment. However, the charge amount was considerably high in the low temperature and low humidity environment, and the image density was less than 1.3 and the density was insufficient.

It is a cross-sectional schematic diagram which shows an example of the carrier for electrostatic latent image developers of this invention. It is a cross-sectional schematic diagram which shows an example of the composite resin particle in this invention. 1 is a schematic diagram illustrating an example of an image forming apparatus of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Carrier 20 Resin coating layer 21 Matrix resin 22 Composite resin particle 23 Electroconductive fine powder 30 Core material 40 Resin 50 which comprises composite resin particle Inorganic particle A, B, C, D Developer 809-812 Developer

Claims (5)

A static coating characterized in that a resin coating layer in which composite resin particles containing at least inorganic particles and melamine resin as constituent components and conductive fine powder are dispersed in a matrix resin is formed on the surface of the core material. Carrier for electrostatic latent image developer. An electrostatic latent image developer formed on a surface of a core material by forming a resin coating layer in which composite resin particles containing at least inorganic particles and melamine resin as constituent components and conductive fine powder are dispersed and contained in a matrix resin An electrostatic latent image developer comprising a carrier for toner and toner. Image formation including developing means for developing an electrostatic latent image on the surface of the electrostatic latent image carrier using at least a developer charged with a developer containing toner and carrier formed on the surface of the developer carrier. In the apparatus, the carrier is formed on the surface of the core material by forming a resin coating layer in which composite resin particles containing at least inorganic particles and melamine resin as constituent components and conductive fine powder are dispersed and contained in the matrix resin. An image forming apparatus characterized by being a carrier. Mixing matrix resin, composite resin particles containing inorganic particles and melamine resin as constituents and conductive fine powder in a solvent having at least the property of dissolving matrix resin but not dissolving composite resin particles containing inorganic particles, A step of preparing a resin coating layer forming solution in which the composite resin particles are dispersed, and a step of applying the resin coating layer forming solution to the surface of the core material and removing the solvent. A method for producing a carrier for an electrostatic latent image developer. At least, using a developer containing a developer carrying member surface to the formed toner and carrier, an image forming method including a developing step of developing the electrostatic latent image of the surface of the electrostatic latent image bearing member, as the carrier , Using a carrier formed by forming on the surface of the core material a resin coating layer in which composite resin particles containing at least inorganic particles and melamine resin as constituent components and conductive fine powder are dispersed and contained in the matrix resin. An image forming method.

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