JP6699331B2 - Carrier, developer, process cartridge, image forming apparatus, and image forming method - Google Patents

Description

  The present invention relates to a carrier, a developer, a process cartridge, an image forming apparatus and an image forming method.

  Image forming apparatuses such as a copying machine, a printer, and a multi-function peripheral use an image forming technique utilizing electrostatic characteristics such as an electrophotographic method and an electrostatic recording method. For example, in electrophotographic image forming technology, charged toner is attached to an electrostatic latent image formed on the surface of a photoconductor, the toner image is developed on the surface of the photoconductor, and the toner image is recorded on a recording medium. An image is formed by transferring and fixing.

  The toner is charged by particles called a carrier, is transported to the photoconductor by the carrier, and adheres to the surface of the photoconductor on which the electrostatic latent image is formed. Further, the carrier after the toner adheres to the photoconductor is collected and reused for charging and transporting the toner.

  In recent years, the technology of copying machines and printers using an electrophotographic system is rapidly expanding from monochrome to full color, and the full color market tends to expand. In forming a full-color image, generally, three color toners of yellow, magenta, and cyan, or four color toners in which black is added is laminated, and all the colors are reproduced. Recently, along with the increase in printing speed, it has been required to improve the charge imparting ability of the carrier to the toner.

  On the other hand, in the field of so-called production printing, which prints or binds a large amount of documents for business use, the market has been expanding in recent years, and higher image quality is required. There is more demand than ever.

  Under such circumstances, various attempts have hitherto been made in the field of image formation by electrophotography. For example, there are a technique of forming a resin layer having a charge imparting function on the surface of a carrier and a technique of forming a resin layer containing fine particles on the surface of a carrier (Patent Documents 1 and 2).

  However, when an image is formed for a long period of time, the carrier wears as the number of printed sheets increases, and the charge imparting function for the toner of the carrier deteriorates. As a result, there is a problem in that toner is scattered outside the developing unit and toner scatters on the white paper portion.

  Further, although a large amount of printing is performed in image formation for a long period of time, it is difficult to suppress density variation and unevenness in density between images when performing a large amount of printing. Therefore, the conventional technique cannot perform stable image formation for a long period of time.

  An object of the present invention is to provide a carrier, a developer, a process cartridge, an image forming apparatus, and an image forming method that can form a stable image even when a large amount of printing is performed for a long period of time.

A carrier according to one embodiment of the present invention is a carrier having magnetic core particles and a coating layer that coats the surface of the core particles, the coating layer containing a resin and tungsten-doped tin oxide as fine particles. The particle size distribution of the fine particles has at least two peaks, the particle size showing a peak having the largest particle size among the peaks is anm, and the particle size showing a peak having the smallest particle size is bnm. When a and b satisfy 5≦a/b≦100, and the BET specific surface area of the carrier is C and the BET specific surface area of the core particle is F, C and F are 20≦C ² It is characterized in that /F≦280 is satisfied.

  According to one aspect of the carrier of the present invention, stable image formation can be performed even when a large amount of printing is performed for a long period of time.

It is a schematic sectional drawing which shows an example of the carrier of this invention. 3 is a graph showing a particle size distribution of fine particles used in an example of the carrier of the present invention. It is a schematic perspective view of the apparatus which measures a volume resistivity about an example of the carrier of this invention. It is a schematic diagram showing an example of a process cartridge of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings as appropriate. FIG. 1 is a schematic sectional view showing an example of the carrier of the present invention. The carrier 1 shown in FIG. 1 mainly includes magnetic core particles and a resin layer 5 that coats the surfaces of the core particles 3. Furthermore, the resin layer 5 contains at least fine particles. The core particles 3, the resin layer 5, and the fine particles 7 are examples of the core particles, the coating layer, and the fine particles of the present invention.

  FIG. 2 is a graph showing the particle size distribution of fine particles used in an example of the carrier of the present invention. In this graph, the horizontal axis represents the particle size [nm] and the vertical axis represents the strength [%]. The fine particles 7 have a particle size distribution in which at least two peaks exist, as shown in FIG. Specifically, the particle size distribution shown in FIG. 2 has five peaks (P1 to P5).

  Of these five peaks, the particle size showing the peak P5 having the maximum particle size (hereinafter referred to as the maximum particle size) is a [nm], and the particle size showing the peak P1 having the minimum particle size (hereinafter, the minimum particle size). Is referred to as b[nm]. At this time, the fine particles 7 satisfy the condition that the maximum particle size a and the minimum particle size b are 5≦a/b≦100.

Further, where C is the BET specific surface area of the carrier 1 and F is the BET specific surface area of the core particles, C and F satisfy the condition of 20≦C ² /F≦280. By satisfying these conditions, the fine particles can be effectively arranged in the coating layer, an optimum surface area can be given to the surface of the carrier, and the deterioration of the carrier shape during long-term printing can be prevented. In particular, the carrier after developing the toner image is collected and reused. However, by using the carrier of the present invention, stable image formation can be performed even when a large amount of printing is performed for a long period of time.

  The fine particles 7 in the resin layer 5 impart hardness to the resin layer 5 (coating layer) that coats the core material particles. Therefore, it is an important factor for suppressing the deterioration of the carrier shape in recent printers that perform high-speed printing. The inventors have made the particle size distribution of the fine particles 7 have two or more peaks, and the maximum particle size a having the maximum particle size peak and the minimum particle size b having the minimum particle size peak are 5≦. It has been found that when the condition of a/b≦100 is satisfied, the fine particles 7 can be effectively arranged in the coating layer and the deterioration of the carrier shape can be suppressed.

  Specifically, if 5≦a/b, a size relationship occurs between the fine particles, and the fine particles can be geometrically arranged in the coating layer. Therefore, it is possible to bring hardness to the coating layer and suppress deterioration of the carrier shape. Further, if a/b≦100, the maximum particle size a does not become too large with respect to the minimum particle size b. Therefore, since it is possible to prevent the fine particles from being separated from the coating layer, deterioration of the carrier shape can be suppressed.

  The particle size of the fine particles 7 can be confirmed by a known method. In the present embodiment, the measurement is performed by the following method. That is, it can be performed by cutting the carrier with a FIB (focused ion beam) and observing the cross section with an SEM or the like.

  Specifically, a sample is attached onto a carbon tape, and osmium is coated to a thickness of about 20 nm for surface protection and conductive treatment. Using a FIB-SEM apparatus (Carl Zeiss (SII), NVision40), accelerating voltage 2.0 kV, aperture 30 μm, High Current ON, detector SE2, InLens, no conductive treatment, W.I. FIB treatment is performed at D 5.0 mm and sample inclination 54°.

  An electron-cooled silicon drift (SDD) detector (Thermo Fisher Scientific, UltraDry) (Φ30 mm 2) and analysis software (Thermo Fisher Scientific, NORAN System 6 (NSS)) were used to accelerate at an acceleration voltage of 3.0 kV and a voltage of 3.0 kV. , High Current ON, conductivity treatment Os, with drift correction, W.I. D 10.0 mm, measurement method Area Scan, integration time 10 sec, integration number 100 times, SEM observation with sample inclination 54° and magnification 10000 times.

  This is taken into a TIFF image, and after using the image processing software (Media Cybernetics, Image-Pro Plus) to form an image of only particles, binarization is performed, and a white part (fine particle part) and a black part The particle size of the white part was measured by dividing the part (resin part). When the fine particles were non-spherical, the particle diameter of the fine particles was measured as a circle equivalent diameter. This method was performed on 1000 particles, and the particle size distribution of the particles was plotted.

  Plotting was performed based on the results of grouping every 5 [nm], and peaks with a frequency of 5% or less were not considered to be peaks. In addition, the extreme value on the plot was defined as the peak.

  Further, in the present invention, the BET specific surface area of the carrier 1 is a very important factor as a function of imparting charge to the toner. A high BET specific surface area means that the number of times of triboelectric charging between the toner and the carrier 1 is increased, and that there is a large area of the carrier 1 capable of providing an electric charge, and the charging ability of the carrier 1 is transmitted to the toner. It means increasing efficiency. Therefore, for high image area or high-speed printing, it is possible to meet the requirement of quickly charging the toner against frictional charging.

  On the other hand, the BET specific surface area of the carrier 1 is affected by the BET specific surface area of the core material particles 3. That is, the BET specific surface area of the carrier 1 changes as the irregularities on the surface of the carrier 1 follow the irregularities of the core material particles 3. It means that the higher the BET specific surface area of the core material particles 3 is, the more convex portions are present on the core material particles 3.

  In the developing device, the carrier 1 receives kinetic energy due to friction or collision and is worn. When the core particles 3 inside the resin layer 5 (coating layer) are exposed to the surface as a result of abrasion, electric charge leaks from the exposed portions, which causes a decrease in the charge and resistance of the carrier 1 and causes scumming or carrier adhesion. Such a problem occurs.

  It is difficult for the coating material to physically adhere to the convex portions of the core material particles 3, and the coating layer partially becomes a thin film. Therefore, the presence of fine particles is likely to be sparse, and the abrasion resistance of the coating layer is weak. As a result, the more convex portions the core material particles have, the more easily problems such as scumming and carrier adhesion occur, which is a fatal problem in long-term printing.

As a result of repeated intensive studies, the inventors focused on the BET specific surface areas of the core material particle and the carrier, and when the BET specific surface area of the carrier was C and the BET specific surface area of the core particle was F, C and F were 20. It has been found that by satisfying the condition of ≦C ² /F≦280, stable image formation can be performed even when a large amount of printing is performed for a long period of time.

  Specifically, sufficient charge control for the image quality required in the field of production printing can be performed over long-term printing, a stable amount of developer can be supplied to the developing area, and low temperature It has been found that it is possible to obtain a carrier and a developer that enable continuous paper passing with a low image area ratio and printing density even in a high-speed machine using a fixing toner.

In particular, in the range of 21≦C ² /F, the core material particles 3 inside the resin layer 5 (coating layer) are less likely to be exposed on the surface due to the protrusions of the core material particles, and the scumming and carrier adhesion are less likely to occur. In addition, since the coating layer has a specific surface area for immediately charging the toner, stable charging can be performed over a long period of printing. On the other hand, in the range of C ² /F≦270, a large amount of fine particles can be contained in the resin layer 5 of the carrier 1, so that the separation of fine particles can be prevented.

The range of C ² /F is preferably 45≦C ² /F≦100. Within this range, the charge imparting ability over a long period of printing can be further stabilized. Further, the range of C ² /F is more preferably 50≦C ² /F≦100. In this range, it is possible to further ameliorate problems due to electrostatic charges such as background stains.

  In the present embodiment, the BET specific surface area of the carrier was measured using 5.0 g of the carrier with a BET specific surface area measuring device (Tristar 3000 manufactured by Shimadzu Corporation). The BET specific surface area of the core particles was also measured by using 5.0 g of the core particles using a BET specific surface area measuring device (Tristar 3000 manufactured by Shimadzu Corporation).

  If the BET specific surface area of the core particles is too small, the BET specific surface area of the carrier also becomes small, so that the number of times of friction between the toner and the carrier is reduced, and the charge imparting ability of the carrier to the toner may be deteriorated. On the other hand, if the BET specific surface area of the core particles is too large, the BET specific surface area of the carrier also increases, so that the surface of the carrier (the surface of the resin layer) is worn (or deteriorated) due to the protrusions of the core material particles as described above. It becomes easy and stable image formation may not be possible over long-term printing.

  Therefore, the BET specific surface area F of the core particles is preferably adjusted so as to satisfy the condition of 0.05≦F≦0.2. As described above, the BET specific surface area of the core particles influences the BET specific surface area of the carrier. However, by adjusting the BET specific surface area of the core particles to such a range, even if the number of friction with the toner is increased, the surface It is possible to provide a carrier that does not easily wear. That is, the durability of the carrier can be improved while maintaining a high charge imparting function of the carrier to the toner.

  The value of the maximum particle size a [nm] of the fine particles 7 is preferably 400≦a≦1800. When 400≦a, it means that the particle size as a whole does not become too small, and the separation from the coating layer due to the kinetic energy received by the particle having a small particle size is suppressed, and the BET specific surface area is maintained for long-term printing. Therefore, the problem of charging such as background stain can be further improved.

  On the other hand, when the maximum particle size a is a≦1800, the particle size of the particles as a whole does not become too large as a whole, and the problem that the resin layer cannot be retained and is detached from the particles having a large particle size is suppressed, and It is possible to maintain the BET specific surface area for printing, and it is possible to further improve the problem of charging such as scumming.

  As the fine particles, conductive fine particles and non-conductive fine particles can be used, and it is also possible to use conductive fine particles and non-conductive fine particles together.

  The conductive fine particles are a filler formed by forming a layer of tin dioxide or indium oxide on a base of an inorganic compound such as aluminum oxide, titanium dioxide, zinc oxide, silicon dioxide, barium sulfate, zirconium oxide, carbon black, ITO, PTO, WTO. , Tin oxide, polyaniline and the like can be used. As the inorganic compound used for the substrate, aluminum oxide and further barium sulfate are preferable.

  As the non-conductive fine particles, inorganic compounds such as aluminum oxide, titanium dioxide, zinc oxide, silicon dioxide, barium sulfate and zirconium oxide can be used, but aluminum oxide and further barium sulfate are preferable.

  In the carrier of the present invention, the resin component in the resin layer 5 (coating layer) hydrolyzes the copolymer represented by the following chemical formula (1) to generate a silanol group, which is crosslinked and coated by condensation using a catalyst. It is preferable that the carrier is obtained by heating after the above.

式中で、Ｒ^１、ｍ、Ｒ^２、Ｒ^３、Ｘ、Ｙは以下に該当するものを示す。Ｒ^１：水素原子、またはメチル基、ｍ：１〜８の整数、Ｒ^２：炭素原子数１〜４のメチル基、エチル基、プロピル基、イソプロピル基、及びブチル基等のアルキル基、Ｒ^３：炭素数１〜８のメチル基、エチル基、プロピル基、イソプロピル基、及びブチル基等のアルキル基、または炭素数１〜４のメトキシ基、エトキシ基、プロポキシ基、ブトキシ基等のアルコキシ基。

In the formula, R ¹ , m, R ² , R ³ , X, and Y represent the following. R ¹ : a hydrogen atom or a methyl group, m: an integer of 1 to 8, R ² : an alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, a propyl group, an isopropyl group, and a butyl group, R ³ : An alkyl group such as a C1-C8 methyl group, an ethyl group, a propyl group, an isopropyl group, and a butyl group, or an alkoxy group such as a C1-C4 methoxy group, an ethoxy group, a propoxy group, and a butoxy group.

  The copolymer represented by the following chemical formula (1) is obtained by radical copolymerizing the monomer A component of the structural unit represented by the chemical formula (2) below and the monomer B component of the structural unit represented by the chemical formula (3) below.

  A component:

式中、Ｒ^１：水素原子、またはメチル基、ｍ：１〜８の整数、Ｒ^２：炭素原子数１〜４の脂肪族炭化水素基であり、メチル基、エチル基、プロピル基、及びブチル基、Ａ成分において、Ｘ＝１０〜９０モル％であり、より好ましくは、３０〜７０モル％である。

In the formula, R ^{1 is a} hydrogen atom or a methyl group, m is an integer of 1 to 8, R ^{2 is} an aliphatic hydrocarbon group having 1 to 4 carbon atoms, and is a methyl group, an ethyl group, a propyl group, and a butyl group. In the group and the component A, X=10 to 90 mol %, and more preferably 30 to 70 mol %.

  The component A represented by the chemical formula (2) has an atomic group, tris(trimethylsiloxy)silane, in which a large number of methyl groups are present in the side chain, and the surface energy increases when the ratio of the component A with respect to the entire resin increases. Becomes smaller, and the adhesion of the resin component and wax component of the toner is reduced. If the content of the component A is less than 10 mol %, a sufficient effect cannot be obtained, and the adhesion of the toner component rapidly increases. On the other hand, when it is more than 90 mol %, the component B and the component C decrease, the crosslinking does not proceed, the toughness becomes insufficient, the adhesion between the core material and the resin layer decreases, and the durability of the carrier film deteriorates. ..

R ² is an alkyl group having 1 to 4 carbon atoms, and as such a monomer component, a tris(trialkylsiloxy)silane compound represented by the following formula is exemplified.

In the following formulae, Me is a methyl group, Et is an ethyl group, and Pr is a propyl group.
_{CH 2 = CMe-COO-C} 3 H 6 -Si (OSiMe 3) 3
_{CH 2 = CH-COO-C} 3 H 6 -Si (OSiMe 3) 3
_{CH 2 = CMe-COO-C} 4 H 8 -Si (OSiMe 3) 3
_{CH 2 = CMe-COO-C} 3 H 6 -Si (OSiEt 3) 3
_{CH 2 = CH-COO-C} 3 H 6 -Si (OSiEt 3) 3
_{CH 2 = CMe-COO-C} 4 H 8 -Si (OSiEt 3) 3
_{CH 2 = CMe-COO-C} 3 H 6 -Si (OSiPr 3) 3
_{CH 2 = CH-COO-C} 3 H 6 -Si (OSiPr 3) 3
_{CH 2 = CMe-COO-C} 4 H 8 -Si (OSiPr 3) 3
The method for producing the component A is not particularly limited, but it can be obtained, for example, by a method in which tris(trialkylsiloxy)silane is reacted with allyl acrylate or allyl methacrylate in the presence of a platinum catalyst. Further, it can be obtained by a method described in JP-A No. 11-217389, in which methacryloxyalkyltrialkoxysilane and hexaalkyldisiloxane are reacted in the presence of a carboxylic acid and an acid catalyst.

  B component:

式中で、Ｒ^１：水素原子、またはメチル基、ｍ：１〜８の整数、Ｒ^２：炭素原子数１〜４の脂肪族炭化水素基であり、メチル基、エチル基、プロピル基、及びブチル基、Ｒ^３：炭素数１〜８のアルキル基（メチル基、エトキシ基、プロポキシ基、ブトキシ基）である。

In the formula, R ^{1 is a} hydrogen atom or a methyl group, m is an integer of 1 to 8, R ^{2 is} an aliphatic hydrocarbon group having 1 to 4 carbon atoms, and a methyl group, an ethyl group, a propyl group, and butyl group, ^{R 3:} an alkyl group having 1 to 8 carbon atoms (a methyl group, an ethoxy group, a propoxy group, a butoxy group).

  That is, the component B is a radically polymerizable difunctional or trifunctional silane compound, and Y=10 to 90 mol %, more preferably 30 to 70 mol %.

  When the content of the component B is less than 10 mol %, the resin layer 3 (coating layer) cannot have sufficient toughness. On the other hand, when it is more than 90 mol %, the resin layer 3 becomes hard and brittle, and film abrasion is likely to occur. In addition, environmental characteristics deteriorate. It is also considered that a large number of hydrolyzed crosslinking components remain as silanol groups, which deteriorates the environmental characteristics (humidity dependency).

  Examples of the component B include 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltriethoxysilane and 3-methacryloxypropylmethyl. Examples thereof include dimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltri(isopropoxy)silane, and 3-acryloxypropyltri(isopropoxy)silane.

  In the present invention, an acrylic compound (monomer) may be added as the C component to the above A component and B component. As the one to which such C component is added, a copolymer represented by the following chemical formula (4) can be mentioned.

式中で、Ｒ^１、ｍ、Ｒ^２、Ｒ^３、Ｘ、Ｙ、及びＺは以下に該当するものを示す。Ｒ^１：水素原子、またはメチル基、ｍ：１〜８の整数、Ｒ^２：炭素原子数１〜４のアルキル基、Ｒ^３は、炭素数１〜８のアルキル基、または炭素数１〜４のアルコキシ基である。

In the formula, R ¹ , m, R ² , R ³ , X, Y, and Z represent the following. R ¹ : a hydrogen atom or a methyl group, m: an integer of 1 to 8, R ² : an alkyl group having 1 to 4 carbon atoms, R ³ is an alkyl group having 1 to 8 carbon atoms, or 1 to 4 carbon atoms Is an alkoxy group.

  A component:

上記化学式（５）に示す化合物（構成単位）は、式中、Ｘ＝１０〜４０モル％である以外は、上記化学式（２）と同様である。

The compound (structural unit) represented by the chemical formula (5) is the same as the chemical formula (2) except that X=10 to 40 mol% in the formula.

  B component:

上記化学式（６）に示す化合物（構成単位）は、式中、Ｘ＝１０〜４０モル％である以外は、上記化学式（３）と同様である。

The compound (structural unit) represented by the chemical formula (6) is the same as the chemical formula (3) except that X=10 to 40 mol% in the formula.

  C component:

式中、Ｚ＝３０〜８０モル％であり、かつ、６０モル％＜Ｙ＋Ｚ＜９０モル％である。

In the formula, Z=30 to 80 mol% and 60 mol%<Y+Z<90 mol%.

  The C component of the chemical formula (6) constitutional unit imparts flexibility to the coating film and improves adhesion between the core material and the coating film. However, if the C component is less than 30 mol%, sufficient adhesiveness cannot be obtained, and if it exceeds 80 mol%, either the X component or the Y component becomes 10 mol% or less, and thus the water repellency of the carrier film is reduced. It becomes difficult to achieve both hardness and flexibility (film scraping).

  The acrylic compound (monomer) as the C component is preferably an acrylic acid ester or a methacrylic acid ester, and specific examples thereof include methyl methacrylate, methyl acrylate, ethyl methacrylate, ethyl acrylate, butyl methacrylate, and butyl acrylate. Of these, alkyl methacrylate is preferable, and methyl methacrylate is particularly preferable. Further, one kind of these compounds may be used alone, or a mixture of two or more kinds may be used.

  Moreover, 2-(dimethylamino)ethyl methacrylate, 2-(dimethylamino)ethyl acrylate, 3-(dimethylamino)propyl methacrylate, and 3-(dimethylamino)propyl acrylate may be used as the C component. Further, one kind of these compounds may be used alone, or a mixture of two or more kinds may be used.

  In addition, as a high durability technology by cross-linking the coating, there is Japanese Patent No. 3691115. Japanese Patent No. 3691115 discloses that the surface of magnetic particles has a radical having at least one functional group selected from the group consisting of an organopolysiloxane having a vinyl group at the end and a hydroxyl group, an amino group, an amide group and an imide group. A carrier for developing an electrostatic charge image, which is coated with a thermosetting resin obtained by crosslinking a copolymer with a copolymerizable monomer with an isocyanate compound, is disclosed, but it has sufficient durability in peeling and scraping of the coating. The current situation is that they have not been obtained.

  Although the reason is not clear enough, in the case of a thermosetting resin obtained by crosslinking the above-mentioned copolymer with an isocyanate-based compound, as can be seen from the structural formula, the isocyanate in the copolymer resin Since the number of functional groups per unit weight that reacts (crosslinks) with the compound is small, a two-dimensional or three-dimensional dense crosslinked structure cannot be formed at the crosslinking point. Therefore, when used for a long time, the coating film is likely to be peeled off or scraped off (the abrasion resistance of the coating film is small), and it is presumed that sufficient durability is not obtained.

  When the film is peeled off or scraped off, the carrier resistance is lowered, which causes a change in image quality and carrier adhesion. Further, the peeling/shaving of the coating lowers the fluidity of the developer, causes a reduction in the amount of scooped up toner, and causes a decrease in image density and scumming due to an increase in TC (toner density) and toner scattering.

  The resin of the present invention is a copolymer resin having a large number of bifunctional or trifunctional crosslinkable functional groups (points) per unit weight (2 to 3 times more per unit weight). However, since this is further cross-linked by polycondensation, it is considered that the coating is extremely tough, is not easily scraped, and has high durability.

  Further, since the cross-linking by the siloxane bond of the present invention has a larger binding energy and is more stable against heat stress than the cross-linking by the isocyanate compound, it is presumed that the temporal stability of the coating film is maintained.

  As the coating resin for the carrier, a silicone resin, an acrylic resin, or a combination of these may be used. Acrylic resin has strong adhesiveness and low brittleness, and thus has very excellent wear resistance, but has high surface energy. Therefore, in consideration of so-called toner spent (a phenomenon in which some toner components such as toner fragments adhere to the surface of the carrier), when combined with a toner that easily spends, the amount of charge due to the accumulation of spent toner components Problems such as deterioration may occur.

  On the other hand, since the silicone resin has a low surface energy, the presence of the silicone resin makes it difficult for the toner component to be spent, and the effect that the spent component is less likely to be accumulated due to film abrasion is obtained. Therefore, the problem caused by this spent can be solved by using the silicone resin together.

  On the other hand, since silicone resin has weak adhesiveness and high brittleness, it also has a weak point that it has poor abrasion resistance. Therefore, by obtaining the properties of these two resins in a well-balanced manner, it is difficult to spent and also has abrasion resistance. It becomes possible to obtain a film, and the improvement effect becomes remarkable. This is because the silicone resin has a low surface energy, so that the toner component is less likely to be spent, and the effect that the spent component is less likely to accumulate due to film abrasion is obtained.

  The term "silicone resin" as used herein refers to all commonly known silicone resins, including straight silicone resins consisting of only organosilosan bonds and silicone resins modified with alkyd, polyester, epoxy, acrylic, urethane, etc. However, the present invention is not limited to this. For example, commercially available straight silicone resins include KR271, KR255, KR152 manufactured by Shin-Etsu Chemical, SR2400, SR2406, SR2410 manufactured by Toray Dow Corning Silicone.

  In this case, it is possible to use the silicone resin alone, but it is also possible to simultaneously use other components that undergo a crosslinking reaction, a charge amount adjusting component, and the like. Further, as the modified silicone resin, Shin-Etsu Chemical's KR206 (alkyd modified), KR5208 (acrylic modified), ES1001N (epoxy modified), KR305 (urethane modified), Toray Dow Corning Silicon SR2115 (epoxy modified). , SR2110 (alkyd modified) and the like.

  The carrier of the present invention preferably has a volume average particle size of 28 μm or more and 40 μm or less. When the volume average particle diameter of the carrier particles is less than 28 μm, carrier adhesion may occur, and when it exceeds 40 μm, reproducibility of image details may be deteriorated and a fine image may not be formed.

  The volume average particle diameter can be measured using, for example, a Microtrac particle size distribution meter (HRA9320-X100, manufactured by Nikkiso Co., Ltd.). The carrier of the present invention preferably has a volume resistivity of 8 to 16 (Log Ω·cm). If the volume resistivity is less than 8 (LogΩ·cm), carrier adhesion may occur in the non-image area, and if it exceeds 16 (LogΩ·cm), the edge effect may be unacceptable.

  The volume resistivity can be measured using the cell shown in FIG. Specifically, the sample (carrier) 7 is filled in a cell in which the electrode 11 and the electrode 13 having a surface area of 2.5 cm×4 cm are housed in the fluororesin container 9 with a distance of 0.2 cm, and the drop height is increased. Tapping is performed 10 times at a tapping speed of 30 times/minute with a length of 1 cm. Next, a direct current voltage of 1000 V was applied between the electrodes 1 and 3, and the resistance value r (Ω) after 30 seconds was measured using a high resistance meter (Yokogawa Hewlett Packard, high resistance meter 4329A). To do. Then, the volume specific resistance value Rv (Ω·cm) is calculated from the equation of Rv=r×(2.5×4)/0.2.

  Examples of the condensation polymerization catalyst include titanium-based catalysts, tin-based catalysts, zirconium-based catalysts, and aluminum-based catalysts. In the present invention, among these various catalysts, among titanium-based catalysts that give excellent results, titanium is particularly preferable. Diisopropoxybis(ethylacetoacetate) is most preferred as the catalyst. It is considered that this is because the effect of promoting the condensation reaction of the silanol group is large and the catalyst is hard to deactivate.

  In the present invention, the coating layer composition preferably contains a silane coupling agent. Thereby, the fine particles can be stably dispersed.

  The silane coupling agent is not particularly limited, but r-(2-aminoethyl)aminopropyltrimethoxysilane, r-(2-aminoethyl)aminopropylmethyldimethoxysilane, r-methacryloxypropyltrimethoxysilane, N -Β-(N-vinylbenzylaminoethyl)-r-aminopropyltrimethoxysilane hydrochloride, r-glycidoxypropyltrimethoxysilane, r-mercaptopropyltrimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, Vinyltriacetoxysilane, r-chloropropyltrimethoxysilane, hexamethyldisilazane, r-anilinopropyltrimethoxysilane, vinyltrimethoxysilane, octadecyldimethyl[3-(trimethoxysilyl)propyl]ammonium chloride, r-chloro Propylmethyldimethoxysilane, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, allyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-aminopropyltrimethoxysilane, dimethyldiethoxysilane, 1,3-divinyltetramethyl Examples thereof include disilazane and methacryloxyethyldimethyl(3-trimethoxysilylpropyl)ammonium chloride, and two or more kinds may be used in combination.

  As a commercial item of a silane coupling agent, AY43-059, SR6020, SZ6023, SH6026, SZ6032, SZ6050, AY43-310M, SZ6030, SH6040, AY43-026, AY43-031, sh6062, Z-6911, sz6300, sz6075,. sz6079, sz6083, sz6070, sz6072, Z-6721, AY43-004, Z-6187, AY43-021, AY43-043, AY43-040, AY43-047, Z-6265, AY43-204M, AY43-048, Z-. 6403, AY43-206M, AY43-206E, Z6341, AY43-210MC, AY43-083, AY43-101, AY43-013, AY43-158E, Z-6920, Z-6940 (Toray Silicone Co., Ltd.), etc. are mentioned. ..

  The addition amount of the silane coupling agent is preferably 0.1 to 10 mass% with respect to the silicone resin. If the addition amount of the silane coupling agent is less than 0.1% by mass, the adhesiveness between the core material particles or the conductive fine particles and the silicone resin may be deteriorated, and the coating layer may drop off during long-term use. If it exceeds 10% by mass, toner filming may occur during long-term use.

  In the present invention, the core particles are not particularly limited as long as they are magnetic materials, but ferromagnetic metals such as iron and cobalt; iron oxides such as magnetite, hematite and ferrite; various alloys and compounds; Resin particles or the like dispersed in resin can be used. Among them, Mn-based ferrite, Mn-Mg-based ferrite, Mn-Mg-Sr ferrite and the like are preferable from the viewpoint of environment.

  The carrier described above can be used as a developer. The developer of the present embodiment contains a toner in addition to the above carrier. The toner contains a binder resin and a colorant, but may be either a monochrome toner or a color toner. Further, in order to apply to an oilless system in which toner fixing prevention oil is not applied to the fixing roller, the toner particles may contain a release agent.

  Such toner generally causes filming easily, but the carrier of the present invention can suppress filming. Therefore, the developer of the present invention has good image quality in image formation for a long period of time. Can be maintained. Further, color toners, especially yellow toners, generally have a problem that color stains occur due to scraping of the coating layer of the carrier, but the developer of the present invention can suppress the occurrence of color stains.

  The toner can be manufactured using a known method such as a pulverization method or a polymerization method. For example, when a toner is produced by a pulverization method, first, a melt-kneaded product obtained by kneading a toner material is cooled, then pulverized and classified to prepare mother particles. Next, in order to further improve transferability and durability, an external additive is added to the base particles to prepare a toner.

  The device for kneading the toner material is not particularly limited, but is a batch type two-roll; Banbury mixer; KTK twin screw extruder (Kobe Steel Co., Ltd.), TEM twin screw extruder (Toshiba Machine Co., Ltd.) Continuous twin-screw extruders such as twin-screw extruder (KCK), PCM twin-screw extruder (Ikegai Iron Works), KEX twin-screw extruder (Kurimoto Iron Works); Co-kneader (Manufactured by Buss Co., Ltd.) and the like, such as continuous type single-screw kneaders.

  When the cooled melt-kneaded product is pulverized, it is coarsely pulverized by using a hammer mill, a rotoplex or the like, and then finely pulverized by a fine pulverizer using a jet stream, a mechanical fine pulverizer, or the like. be able to. In addition, it is preferable to grind so that the average particle diameter becomes 3 to 15 μm.

  Furthermore, when classifying the crushed melt-kneaded product, a wind-powered classifier or the like can be used. In addition, it is preferable to perform classification so that the average particle diameter of the base particles is 5 to 20 μm. When the external additive is added to the base particles, the external additive is crushed and adhered to the surface of the base particles by mixing and stirring using a mixer.

  The binder resin contained in the toner is not particularly limited, but homopolymers of styrene such as polystyrene, poly-p-styrene, and polyvinyltoluene and their substitution products; styrene-p-chlorostyrene copolymer, styrene-propylene copolymer. Polymer, styrene-vinyltoluene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-methacrylic acid copolymer, styrene-methyl methacrylate copolymer, styrene-methacrylic acid Ethyl copolymer, styrene-butyl methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl methyl ketone copolymer , Styrene-butadiene copolymers, styrene-isoprene copolymers, styrene-maleic acid ester copolymers, and other styrene-based copolymers; polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene , Polyester, polyurethane, epoxy resin, polyvinyl butyral, polyacrylic acid, rosin, modified rosin, terpene resin, phenol resin, aliphatic or aromatic hydrocarbon resin, aromatic petroleum resin and the like. Also, two or more of these may be used in combination.

  The binder resin for pressure fixing is not particularly limited, but polyolefins such as low molecular weight polyethylene and low molecular weight polypropylene; ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, styrene-methacrylic acid copolymer , Ethylene-methacrylic acid ester copolymers, ethylene-vinyl chloride copolymers, ethylene-vinyl acetate copolymers, olefin copolymers such as ionomer resins; epoxy resins, polyesters, styrene-butadiene copolymers, polyvinylpyrrolidone, Examples thereof include methyl vinyl ether-maleic anhydride copolymer, maleic acid-modified phenol resin, and phenol-modified terpene resin. Also, two or more of these may be used in combination.

  The colorant (pigment or dye) contained in the toner is not particularly limited, but cadmium yellow, mineral fast yellow, nickel titanium yellow, navels yellow, naphthol yellow S, Hansa yellow G, Hansa yellow 10G, benzidine yellow GR, Yellow pigments such as quinoline yellow lake, permanent yellow NCG and tartrazine lake; orange pigments such as molybdenum orange, permanent orange GTR, pyrazolone orange, balkan orange, indanthrene brilliant orange RK, benzidine orange G, indanthrene brilliant orange GK. Red pigments such as red iron oxide, red cadmium red, permanent red 4R, resole red, pyrazolone red, watching red calcium salt, lake red D, brilliant carmine 6B, eosin lake, rhodamine lake B, alizarin lake, brilliant carmine 3B; fast violet B , Purple pigments such as methyl violet lake; cobalt blue, alkali blue, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, phthalocyanine blue partial chlorinated compounds, blue pigments such as fast sky blue and indanthrene blue BC; chrome green, Green pigments such as chromium oxide, pigment green B and malachite green lake; carbon black, oil furnace black, channel black, lamp black, acetylene black, azine dyes such as aniline black, metal salt azo dyes, metal oxides, composite metals. Examples include black pigments such as oxides. Also, two or more of these may be used in combination.

  The release agent is not particularly limited, and examples thereof include polyolefins such as polyethylene and polypropylene, fatty acid metal salts, fatty acid esters, paraffin wax, amide wax, polyhydric alcohol wax, silicone varnish, carnauba wax, and ester wax. .. Also, two or more of these may be used in combination.

  Further, the toner may further contain a charge control agent. The charge control agent is not particularly limited, but includes nigrosine; an azine dye having an alkyl group having 2 to 16 carbon atoms (see Japanese Patent Publication No. 42-1627); C.I. I. Basic Yellow 2 (C.I. 41000), C.I. I. Basic Yellow 3, C.I. I. Basic Red 1 (C.I. 45160), C.I. I. Basic Red 9 (C.I. 42500), C.I. I. Basic Violet 1 (C.I. 42535), C.I. I. Basic Violet 3 (C.I. 42555), C.I. I. Basic Violet 10 (C.I. 45170), C.I. I. Basic Violet 14 (C.I. 42510), C.I. I. Basic Blue 1 (C.I. 42025), C.I. I. Basic Blue 3 (C.I. 51005), C.I. I. Basic Blue 5 (C.I. 42140), C.I. I. Basic Blue 7 (C.I. 42595), C.I. I. Basic Blue 9 (C.I. 52015), C.I. I. Basic Blue 24 (C.I. 52030), C.I. I. Basic Blue 25 (C.I. 52025), C.I. I. Basic Blue 26 (C.I. 44045), C.I. I. Basic Green 1 (C.I. 42040), C.I. I. Basic dyes such as Basic Green 4 (C.I. 42000); lake pigments of these basic dyes; C.I. I. Solvent Black 8 (C.I.26150), quaternary ammonium salts such as benzoylmethylhexadecyl ammonium chloride, decyl trimethyl chloride; dialkyltin compounds such as dibutyl and dioctyl; dialkyltin borate compounds; guanidine derivatives; vinyl having an amino group. -Based polymers, polyamine resins such as condensation polymers having amino groups; described in JP-B-41-20153, JP-B-43-27596, JP-B-44-6397, and JP-B-45-26478. Metal salt of monoazo dye; salicylic acid described in JP-B-55-42752 and JP-B-59-7385; Zn, Al, Co, Cr, Fe, etc. of dialkyl salicylic acid, naphthoic acid and dicarboxylic acid Examples thereof include sulfonated copper phthalocyanine pigments, organic boron salts, fluorine-containing quaternary ammonium salts, calixarene compounds, and the like, but two or more kinds may be used in combination. For color toners other than black, white metal salts of salicylic acid derivatives and the like are preferable.

  The external additive is not particularly limited, but inorganic particles such as silica, titanium oxide, alumina, silicon carbide, silicon nitride, and boron nitride; a polyamine having an average particle size of 0.05 to 1 μm obtained by a soap-free emulsion polymerization method. Resin particles such as methyl methacrylate particles and polystyrene particles may be mentioned. Also, two or more of these may be used in combination. Among them, metal oxide particles such as silica and titanium oxide whose surface is hydrophobized are preferable. Furthermore, by using both hydrophobized silica and hydrophobized titanium oxide in combination, and by increasing the addition amount of hydrophobized titanium oxide as compared to hydrophobized silica, it is possible to increase humidity A toner having excellent charge stability can be obtained.

  By applying the carrier of the present invention as a replenishment developer composed of a carrier and toner and applying it to an image forming apparatus that forms an image while discharging the excess developer in the developing device, a stable image can be obtained for a very long time. Quality is obtained. That is, the deteriorated carrier in the developing device is replaced with the non-deteriorated carrier in the replenishment developer, and the charge amount is kept stable for a long period of time, and a stable image can be obtained.

  This method is particularly effective for high image area printing. The main cause of carrier deterioration during high image area printing is carrier charge deterioration due to toner spent on the carrier. In this case, by using this method, the carrier replenishment amount also increases, so that the deteriorated carrier is replaced more frequently. As a result, a stable image can be obtained for an extremely long period of time.

  In this case, the mixing ratio of the replenishment developer is preferably 2 to 50% by mass of the toner with respect to 1% by mass of the carrier. If the toner content is less than 2% by mass, the amount of the replenishing carrier is too large, the carrier is excessively supplied, and the carrier concentration in the developing device becomes too high, so that the charge amount of the developer tends to increase. Further, as the developer charge amount increases, the developing ability decreases and the image density decreases. On the other hand, if it exceeds 50% by mass, the proportion of carriers in the replenishment developer decreases, so that the replacement of carriers in the image forming apparatus decreases, and the effect on carrier deterioration cannot be expected.

  FIG. 4 is a schematic view showing an example of the process cartridge of the present invention. The process cartridge 17 integrally supports a photoconductor 19, a charging unit 21, a developing unit 23, a transfer unit 25, and a cleaning unit 29. The process cartridge 17 can be attached to and detached from a main body of an image forming apparatus such as a copying machine, a printer, a multifunction machine, or the like.

  The photoconductor 19 is made of a photoconductive material and is rotatably arranged at a predetermined peripheral speed. The photoconductor 19 is precharged by the charging unit 21, and an electrostatic latent image (not shown) is formed due to the exposure of the exposure light 22 to form an uncharged portion on the surface of the photoconductor 19. That is, the photoconductor 19 functions as an electrostatic latent image carrier.

  The charging unit 21 has a function of charging the photoreceptor 19 before being exposed. Specifically, the charging unit 21 uniformly charges the peripheral surface of the photoconductor 19 to a predetermined positive or negative potential.

  The developing unit 23 develops the electrostatic latent image formed on the photoconductor 19 by the exposure of the light 22 with a developer to form a toner image (not shown). As the developer, the above-described developer (developer containing carrier and toner) is used. Further, the above-mentioned replenishing developer can be appropriately replenished to the developer.

  The transfer unit 25 transfers the toner image formed on the photoconductor 19 to a recording medium. Specifically, the transfer unit 25 rotates in synchronization with the rotation of the photoconductor 19 and transfers the toner image onto the recording medium (transfer paper) 27 fed between the photoconductor 19 and the transfer unit 25.

  The cleaning unit 29 removes the toner remaining on the photoconductor 19 after transferring the toner image formed on the photoconductor 19 to the transfer paper 27. The cleaning unit 29 is provided with a charge removing unit (not shown). The charge removing unit removes the electric charge remaining on the photoconductor 19, and the photoconductor 19 returns to the state before being charged by the charging unit 21.

  Hereinafter, a method of forming an image using the image forming apparatus equipped with the process cartridge 17 will be described. First, the photosensitive member 19 is rotationally driven at a predetermined peripheral speed, and the charging unit 21 uniformly charges the peripheral surface of the photosensitive member 19 to a predetermined positive or negative potential.

  Next, the peripheral surface of the photoconductor 19 is irradiated with exposure light 22 from an unillustrated exposing means (for example, an exposing means of a slit exposing type, an exposing device for scanning exposure with a laser beam, etc.), and electrostatic latent images are sequentially formed. It Further, the electrostatic latent image formed on the peripheral surface of the photoconductor 19 is developed by the developing device 23 using the developer of the present invention to form a toner image.

  Next, the toner image formed on the peripheral surface of the photoconductor 19 is synchronized with the rotation of the photoconductor 19 and is transferred between the photoconductor 19) and the transfer unit 25 from a paper feeding unit (not shown). 27 are sequentially transferred. Further, the transfer paper 27 on which the toner image has been transferred is separated from the peripheral surface of the photoconductor 19 and introduced into a fixing unit (not shown) to be fixed, and then printed as a copy to the outside of the image forming apparatus. Will be out.

  On the other hand, the surface of the photoconductor 19 after the transfer of the toner image is cleaned by removing the residual toner by the cleaning unit 29, and then discharged by the discharging unit (not shown). As a result, the photoconductor 19 is repeatedly used for image formation.

(Image forming method)
An example of the image forming method of the present invention includes a latent image forming step of forming an electrostatic latent image on a photoconductor that functions as an electrostatic latent image carrier, and an electrostatic latent image formed on the photoconductor. A developing step of developing with a developer to form a toner image, a transfer step of transferring the toner image formed on the photoconductor to a recording medium, and a fixing step of fixing the toner image transferred to the recording medium. Have and. The image forming method of this example can be carried out using the above-mentioned process cartridge 17 used in the present embodiment.

  According to the image forming method of the present example, a toner image is formed using the developer containing the carrier used in the present embodiment, so that stable image formation is performed even when a large amount of printing is performed for a long period of time. be able to.

(Image forming device)
An example of the image forming apparatus of the present invention includes, though not particularly shown, a photoconductor as an electrostatic latent image carrier, a charging unit for charging the photoconductor, and an exposure for forming an electrostatic latent image on the photoconductor. Means, developing means for developing the electrostatic latent image formed on the electrostatic latent image carrier with the above-mentioned developer to form a toner image, and forming means on the electrostatic latent image carrier. A transfer unit that transfers the formed toner image to the recording medium and a fixing unit that fixes the toner image transferred to the recording medium are provided.

  Further, other means, for example, a charge removing means, a cleaning means, a recycling means, a control means, etc. may be provided as needed. The image forming apparatus of this example can be configured using the above-described process cartridge 17 used in this embodiment. According to such an image forming apparatus, since a toner image is formed using the developer containing the carrier used in the present embodiment, stable image formation is performed even when a large amount of printing is performed for a long period of time. be able to.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.

(Resin synthesis example 1)
First, 300 g of toluene was put into a flask equipped with a stirrer and heated to 90° C. under a nitrogen gas stream. _{CH 2 = CMe-COO-C} 3 H 6 -Si (OSiMe 3) 3 ( wherein, Me is a methyl group.) Thereto represented by 3-methacryloxypropyl tris (trimethylsiloxy) silane 84.4 g ( 200 mmol) (manufactured by Chisso Corporation, Silaplane TM-0701T), 3-methacryloxypropylmethyldiethoxysilane 39 g (150 mmol), methyl methacrylate 65.0 g (650 mmol), and 2,2′-azobis. A mixture of 0.58 g (3 mmol) of 2-methylbutyronitrile was added dropwise over 1 hour.

  After the completion of the dropping, a solution of 0.06 g (0.3 mmol) of 2,2′-azobis-2-methylbutyronitrile in 15 g of toluene was further added to the mixture (2,2′-azobis-2-methylbutyronitrile). A total amount of ronitrile (0.64 g=3.3 mmol) was mixed at 90 to 100° C. for 3 hours to perform radical copolymerization to obtain a methacrylic copolymer R1.

(Example of fine particle production)
100 g of aluminum oxide (AKP-30, manufactured by Sumitomo Chemical Co., Ltd.) was dispersed in 1 liter of water to give a suspension, and this liquid was heated to 70°C. A solution prepared by dissolving 150 g of stannic chloride and 4.5 g of phosphorus pentoxide in 1.5 liter of 2N hydrochloric acid and 12% by mass aqueous ammonia are added to the suspension so that the pH of the suspension becomes 7 to 8. Over 3 hours. After the dropping, the suspension was filtered and washed to obtain a cake, which was dried at 110°C. Next, the dry powder was treated in a nitrogen stream at 500° C. for 1 hour to carry out air stream classification to obtain fine particles E1. The obtained fine particles had an equivalent circle diameter of 600 nm.

  Barium sulfate (manufactured by Sakai Chemical Industry Co., Ltd.) was used as another fine particle, and the equivalent circle diameter was adjusted by performing air flow classification. A production example is shown below.

また別の微粒子として市販のタングステンドープ錫を用い、気流分級を行うことで円相当径の調整を行った。作製例を以下に示す。

Further, commercially available tungsten-doped tin was used as another fine particle, and the equivalent circle diameter was adjusted by performing air flow classification. A production example is shown below.

また別の微粒子としてアルミナ（住友化学社製）を用い、気流分級を行うことで円相当径の調整を行った。作製例を以下に示す。

Alumina (manufactured by Sumitomo Chemical Co., Ltd.) was used as another fine particle, and the equivalent circle diameter was adjusted by performing air flow classification. A production example is shown below.

（芯材製造例１）
ＭｎＣＯ_３、Ｍｇ（ＯＨ）_２、およびＦｅ_２Ｏ_３粉を秤量し混合して混合粉を得た。この混合粉を、加熱炉により９００℃、３時間、大気雰囲気下で仮焼し、得られた仮焼物を冷却後、粉砕して、ほぼ粒径７μｍ径の粉体とした。この粉体を１ｗｔ％の分散剤を水と共に加えてスラリーとし、このスラリーをスプレードライヤに供給して造粒し、平均粒径約４０μｍの造粒物を得た。

(Core material production example 1)
MnCO ₃ , Mg(OH) ₂ , and Fe ₂ O ₃ powder were weighed and mixed to obtain a mixed powder. This mixed powder was calcined in an air atmosphere at 900° C. for 3 hours in a heating furnace, and the calcined product obtained was cooled and then pulverized to obtain a powder having a diameter of approximately 7 μm. A 1 wt% dispersant was added to this powder together with water to form a slurry, and this slurry was supplied to a spray dryer for granulation to obtain a granulated product having an average particle size of about 40 μm.

This granulated product was loaded into a firing furnace and fired at 1150° C. for 5 hours in a nitrogen atmosphere. The obtained calcined product was crushed with a crusher, and the particle size was adjusted by sieving to obtain spherical ferrite particles C1 having a volume average particle size of about 35 μm and a BET specific surface area of 0.07 m ² /g.

  The volume average particle diameter is set to a material refractive index of 2.42, a solvent refractive index of 1.33, and a concentration of about 0.06 in water using a Microtrac particle size distribution meter (HRA9320-X100 manufactured by Nikkiso Co., Ltd.). Was measured.

(Core material production example 2)
MnCO ₃ , Mg(OH) ₂ , Fe ₂ O ₃ , and SrCO ₃ powder were weighed and mixed to obtain a mixed powder. This mixed powder was calcined in an air atmosphere at 800° C. for 2 hours in a heating furnace, and the calcined product obtained was cooled and then pulverized to obtain a powder having a particle size of 3 μm or less. Water was added to this powder together with a 1 wt% dispersant to form a slurry, and this slurry was supplied to a spray dryer for granulation to obtain a granulated product having an average particle size of about 40 μm. This granulated product was loaded into a firing furnace and fired at 1120° C. for 4 hours in a nitrogen atmosphere.

The obtained calcined product was crushed with a crusher, and then the particle size was adjusted by sieving to obtain spherical ferrite particles C2 having a volume average particle size of about 35 μm and a BET specific surface area of 0.18 m ² /g.

(Core material production example 3)
MnCO ₃ , Mg(OH) ₂ , and Fe ₂ O 3 powder were weighed and mixed to obtain a mixed powder. This mixed powder was calcined in an air atmosphere at 1400° C. for 5 hours in a heating furnace, and the calcined material obtained was cooled and then pulverized to obtain a powder having a particle diameter of approximately 7 μm. A 1 wt% dispersant and water were added to this powder to make a slurry, and this slurry was supplied to a spray dryer for granulation to obtain a granulated product having an average particle size of about 40 μm.

This granulated product was loaded into a firing furnace and fired at 1550° C. for 8 hours in a nitrogen atmosphere. The obtained calcined product was crushed by a crusher, and then the particle size was adjusted by sieving to obtain spherical ferrite particles C3 having a volume average particle size of about 35 μm and a BET specific surface area of 0.02 m ² /g.

(Carrier manufacturing example 1)
Silicone resin solution (solid content 20% by mass): 646% by mass, aminosilane (solid content 100% by mass): 11.7% by mass, B1:215% by mass as fine particles, W1:215% by mass, titanium diisopropoxy as catalyst 31.3% by mass of bis(ethylacetoacetate) (TC-750 manufactured by Matsumoto Fine Chemical Co., Ltd.) was diluted with 750% by mass of toluene to obtain a resin solution.

  C1 was used as the core particles, and atomizing nozzles were used in a fluidized bed type coating apparatus, and the temperature in the fluidized tank was controlled to 65° C. for each coating/drying. The obtained carrier was baked in an electric furnace at 250° C. for 1 hour to obtain carrier 1.

(Carrier manufacturing example 18)
Methacrylic copolymer having a weight average molecular weight of 35,000 obtained in Resin Synthesis Example 1 (solid content 20% by mass): 272% by mass, silicone resin solution (solid content 20% by mass): 323% by mass, aminosilane (solid 100% by mass): 11.7% by mass, B1:215% by mass as fine particles, W1:215% by mass, titanium diisopropoxybis(ethylacetoacetate) as catalyst (Matsumoto Fine Chemical Co., TC-750) 31. 3 mass% was diluted with 750 mass% of toluene to obtain a resin solution.

  C1 was used as the core particles, and atomizing nozzles were used in a fluidized bed type coating apparatus, and the temperature in the fluidized tank was controlled to 65° C. for each coating/drying. The obtained carrier was baked in an electric furnace at 250° C. for 1 hour to obtain a carrier 18.

(Carrier manufacturing examples 2 to 17, 19 to 27)
A carrier was produced in the same manner as in Carrier Production Example 1 except that the materials and the number of parts were changed as shown in Table 4 below. The unit of the numerical values shown in Table 4 is% by mass.

得られたキャリア特性を下表に示す。

The carrier properties obtained are shown in the table below.

＜トナー製造例＞
−ポリエステル樹脂Ａの合成−
冷却管、攪拌機及び窒素導入管の付いた反応槽中に、ビスフェノールＡのエチレンオキシド２モル付加物６５質量％、ビスフェノールＡのプロピオンオキシド３モル付加物８６質量％、テレフタル酸２７４質量％及びジブチルスズオキシド２質量％を投入し、常圧下、２３０℃で１５時間反応させた。次に、５〜１０ｍｍＨｇの減圧下、６時間反応させて、ポリエステル樹脂Ａを合成した。

<Toner manufacturing example>
-Synthesis of Polyester Resin A-
In a reaction vessel equipped with a cooling pipe, a stirrer and a nitrogen introduction pipe, 65% by mass of an ethylene oxide 2 mol adduct of bisphenol A, 86% by mass of a bisphenol A propion oxide 3 mol adduct, 274% by mass of terephthalic acid and dibutyltin oxide 2 were added. Mass% was added, and the mixture was reacted at 230° C. for 15 hours under normal pressure. Next, the polyester resin A was synthesized by reacting for 6 hours under a reduced pressure of 5 to 10 mmHg.

  The obtained polyester resin A has a number average molecular weight (Mn) of 2,300, a weight average molecular weight (Mw) of 8,000, a glass transition temperature (Tg) of 58° C., an acid value of 25 mgKOH/g, and a hydroxyl value. It was 35 mg KOH/g.

-Synthesis of styrene acrylic resin A-
In a reaction tank equipped with a cooling pipe, a stirrer and a nitrogen introducing pipe, 300% by mass of ethyl acetate, 185% by mass of styrene, 115% by mass of acrylic monomer and 5% by mass of azobisisobutylnitrile were charged, and the mixture was cooled to 65% under nitrogen atmosphere. The reaction was carried out at ℃ (normal pressure) for 8 hours. Next, after adding 200 mass% of methanol and stirring for 1 hour, the supernatant was removed and dried under reduced pressure to synthesize styrene-acrylic resin A. The obtained styrene-acrylic resin A had Mw of 20,000 and Tg of 58°C.

-Synthesis of prepolymer (polymer capable of reacting with active hydrogen group-containing compound)-
In a reaction vessel equipped with a cooling pipe, a stirrer and a nitrogen introducing pipe, 682% by mass of bisphenol A ethylene oxide 2 mol adduct, 81% by mass of bisphenol A propylene oxide 2 mol adduct, 283% by mass of terephthalic acid, trimellitic anhydride. 22% by mass and 2% by mass of dibutyltin oxide were charged and reacted at 230° C. for 8 hours under normal pressure. Then, they were reacted for 5 hours under reduced pressure of 10 to 15 mHg to synthesize an intermediate polyester.

  The obtained intermediate polyester has a number average molecular weight (Mn) of 2,100, a weight average molecular weight (Mw) of 9,600, a glass transition temperature (Tg) of 55° C., an acid value of 0.5, and a hydroxyl value. It was 49.

  Next, in a reaction vessel equipped with a cooling pipe, a stirrer and a nitrogen introducing pipe, 411% by mass of the intermediate polyester, 89% by mass of isophorone diisocyanate and 500% by mass of ethyl acetate were charged and reacted at 100° C. for 5 hours. Then, a prepolymer (a polymer capable of reacting with an active hydrogen group-containing compound) was synthesized.

  The free isocyanate content of the obtained prepolymer was 1.60% by mass, and the solid content concentration of the prepolymer (after standing at 150° C. for 45 minutes) was 50% by mass.

-Synthesis of ketimine (compound containing active hydrogen group)-
30% by mass of isophoronediamine and 70% by mass of methyl ethyl ketone were charged into a reaction vessel equipped with a stir bar and a thermometer, and reacted at 50° C. for 5 hours to synthesize a ketimine compound (active hydrogen group-containing compound). The amine value of the obtained ketimine compound (the above-mentioned compound containing an active hydrogen machine) was 423.

-Preparation of masterbatch-
Henschel mixer (manufactured by Mitsui Mining Co., Ltd.) was used in which 540% by mass of water 1000% by mass, DBP oil absorption 42 mL/100 g, pH 9.5 carbon black (Degussa Co., Printex 35) and 1200% by mass polyester resin A. Mixed with. Next, the obtained mixture was kneaded at 150° C. for 30 minutes using a two-roll mill, rolled and cooled, and pulverized with a pulverizer (manufactured by Hosokawa Micron Co., Ltd.) to prepare a masterbatch.

-Preparation of aqueous medium-
306% by mass of ion-exchanged water, 265% by mass of a suspension of 10% by mass of tricalcium phosphate and 1.0% by mass of sodium dodecylbenzenesulfonate were mixed and stirred to uniformly dissolve them to prepare an aqueous medium.

-Measurement of critical micelle concentration-
The critical micelle concentration of the surfactant was measured by the following method. Analysis was performed using a surface tensiometer (manufactured by KSV Instruments, Sigma) using an analysis program in the surface tensiometer. The surfactant was dropped in 0.01 wt% with respect to the aqueous medium, and the interfacial tension after stirring and standing was measured. From the obtained surface tension curve, the surfactant concentration at which the interfacial tension does not decrease even when the surfactant was dropped was calculated as the critical micelle concentration. When the critical micelle concentration of sodium dodecylbenzene sulfonate with respect to the aqueous medium was measured with a surface tensiometer, it was 0.05 wt% with respect to the weight of the aqueous medium.

-Preparation of toner material liquid-
70% by mass of the polyester resin A, 10% by mass of the prepolymer and 100% by mass of ethyl acetate were placed in a beaker and dissolved by stirring. Paraffin wax 5 mass% (manufactured by Nippon Seiro Co., Ltd., HNP-9) (melting point: 75° C.), methyl ethyl ketone dispersion paste (manufactured by Nissan Chemical Industries, Ltd., MEK-ST) 2 mass%, and masterbatch 10 mass% as a release agent. In addition, using a bead mill Ultra Visco Mill (manufactured by IMEX Co., Ltd.), a liquid feed rate of 1 kg/hour, a peripheral velocity of a disk of 6 m/sec, and a condition of filling 80% by volume of zirconia beads having a particle diameter of 0.5 mm. After 3 passes, 2.7 mass% of the above ketimine was added and dissolved to prepare a toner material liquid.

-Preparation of dispersion liquid-
150% by mass of the above aqueous medium phase was placed in a container and stirred at a rotation speed of 12000 rpm using a TK homomixer (made by Tokushu Kika Kogyo Co., Ltd.), and 100% by mass of the dispersion liquid of the above toner material was added thereto. A dispersion (emulsified slurry) was prepared by mixing for 10 minutes.

-Removal of organic solvent-
100% by mass of the emulsified slurry was charged into a Kolben equipped with a stirrer and a thermometer, and the solvent was removed for 12 hours at 30° C. while stirring at a stirring peripheral speed of 20 m/min.

-Washing-
After 100% by mass of the emulsified slurry was filtered under reduced pressure, 100% by mass of ion-exchanged water was added to the filter cake, mixed with a TK homomixer (10 minutes at a rotation speed of 12000 rpm), and then filtered. Ion-exchanged water (300% by mass) was added to the obtained filter cake, the mixture was mixed with a TK type homomixer (at a rotation speed of 12000 rpm for 10 minutes), and then filtration was performed twice. 20% by mass of a 10% by mass aqueous sodium hydroxide solution was added to the obtained filter cake, mixed with a TK type homomixer (30 minutes at a rotation speed of 12000 rpm), and then filtered under reduced pressure.

  Ion-exchanged water (300% by mass) was added to the obtained filter cake, and the mixture was mixed with a TK homomixer (rotation speed 12000 rpm for 10 minutes) and then filtered. Ion-exchanged water (300% by mass) was added to the obtained filter cake, the mixture was mixed with a TK type homomixer (at a rotation speed of 12000 rpm for 10 minutes), and then filtration was performed twice. Further, 20% by mass of 10% by mass hydrochloric acid was added to the obtained filter cake, mixed with a TK type homomixer (at a rotation speed of 12000 rpm for 10 minutes), and then filtered.

-Adjusting the amount of surfactant-
To the filter cake obtained by the above washing, 300% by mass of ion-exchanged water was added, and the electric conductivity of the toner dispersion liquid when mixed with a TK type homomixer (10 minutes at a rotation speed of 12000 rpm) was measured. The surfactant concentration of the toner dispersion liquid was calculated from the calibration curve of the surfactant concentration prepared in. From that value, ion-exchanged water was added so that the surfactant concentration was the target surfactant concentration of 0.05 wt %, and a toner dispersion liquid was obtained.

-Surface treatment process-
The toner dispersion liquid adjusted to the predetermined surfactant concentration as described above was heated in a water bath at a heating temperature T1=55° C. for 10 hours while being mixed at 5000 rpm using a TK homomixer. Thereafter, the toner dispersion liquid was cooled to 25° C. and filtered. Further, 300% by mass of ion-exchanged water was added to the obtained filter cake, and the mixture was mixed with a TK homomixer (at a rotation speed of 12000 rpm for 10 minutes) and then filtered.

-Dry-
The final filter cake obtained was dried at 45° C. for 48 hours with a circulating air drier, and sieved with a mesh having a mesh of 75 μm to obtain toner base particles 1.

-External processing-
Further, with respect to 100% by mass of the toner base particles 1, 3.0% by mass of hydrophobic silica having an average particle size of 100 nm, 1.0% by mass of titanium oxide having an average particle size of 20 nm, and hydrophobicity of 15 nm of the average particle size. 1.5% by mass of silica fine powder was mixed with a Henschel mixer to obtain [Toner 1].

<Preparation of developer>
[Carrier 1] to [Carrier 27] (930% by mass) obtained in Examples and Comparative Examples and Toner 1 (70% by mass) were mixed and stirred at 81 rpm for 5 minutes using a Turbuler mixer, and then evaluated. [Developer 1] to [Developer 27] were manufactured. Further, the replenishment developer was prepared using the above carrier and toner so that the toner concentration would be 95% by mass.

<Developer characteristic evaluation>
Using the obtained developer, image evaluation was performed using a digital color copying machine/printer complex machine (RICOH Pro C7110S manufactured by Ricoh Co., Ltd.), which is an example of an image forming apparatus equipped with the process cartridge of the present invention. Specifically, the above machine was put in an environment evaluation room (25° C., 55% room temperature and normal humidity environment) and left for one day, and then the developers 1 to 27 and toner 1 of Examples and Comparative Examples were used. The initial background stain was evaluated.

<Soil dirt>
The blank image is stopped during development, the toner on the photoconductor after development is tape-transferred, and the difference (ΔID) from the image density of the untransferred tape is measured by a spectrometer (X-Rite 938 Spectrodensitometer). ). The evaluation criteria are shown below.
0 or more and less than 0.003: Rank A (very good)
0.003 or more and less than 0.006: Rank B (very good)
0.006 or more and less than 0.009: Rank C (good)
0.009 or more and less than 0.015: Rank D (available)
0.015 or more and less than 0.025: Rank E (allowable limit)
0.025 or higher: Rank F (defective)
Next, running evaluation was performed. Using a developer 1 to 27 and toner 1 of Examples and Comparative Examples in a digital color copying machine/printer multifunction machine (RICOH Pro C7110S manufactured by Ricoh Co., Ltd.), which is an example of an image forming apparatus equipped with the process cartridge of the present invention. Initially and after running 40,000 and 100,000 sheets at an image area ratio of 40%, the background stain was evaluated in the same manner. The evaluation criteria were the same as above.

  Next, solid carrier adhesion evaluation was performed. Using a developer 1 to 27 and toner 1 of Examples and Comparative Examples in a digital color copier/printer multifunction machine (RICOH Pro C7110S manufactured by Ricoh Co., Ltd.), which is an example of an image forming apparatus including the process cartridge of the present invention, After running 100,000 sheets and 200,000 sheets at an image area ratio of 2.5%, the adhesion of solid carriers shown below was evaluated. The evaluation criteria are shown below.

<Adhesion of solid carrier>
After running the predetermined number of sheets, a solid image is formed under predetermined developing conditions (charging potential (Vd): -600V, potential after exposure of image portion (solid original): -100V, developing bias: DC -500V). Image formation was interrupted by, for example, turning off the power, and the number of adhered carriers on the photoconductor after transfer was counted and evaluated. The area to be evaluated was a 10 mm×100 mm area on the photoconductor.

  Rank A is a state where the number of carrier attachments is 0, Rank B is a state where the number of carrier attachments is 1 to 3, Rank C is a state where the number of carrier attachments is 4 to 7, and Rank D is a state where carrier attachments are the number. The number of carriers is 7 to 10, Rank E is the number of carrier attachments of 11 to 15, and Rank F is the number of carrier attachments of 16 or more. Ranks A to E were accepted and Rank F was rejected.

表６より、比較例１〜９では、地汚れ、ベタキャリア付着の結果がいずれもＲａｎｋ Ｆを含む結果となった。これに対して実施例１〜実施例１８（２０≦Ｃ^２／Ｆ≦２８０）では、地汚れ（１０万枚）、ベタキャリア付着（２０万枚）の結果はいずれもＲａｎｋ Ｅ以上となった。また、実施例１〜実施例１８では、芯材粒子のＢＥＴ比表面積が０．０５≦Ｆ≦０．２の範囲に含まれている。

From Table 6, in Comparative Examples 1 to 9, the results of the background fouling and the solid carrier adhesion all included Rank F. On the other hand, in Examples 1 to 18 (20≦C ² /F≦280), the results of background stain (100,000 sheets) and solid carrier adhesion (200,000 sheets) were all Rank E or higher. .. In addition, in Examples 1 to 18, the BET specific surface area of the core material particles is included in the range of 0.05≦F≦0.2.

  In particular, except for Example 8 (a=300) and Example 11 (a=2500) (5≦a/b≦100), scumming (100,000 sheets) is Rank D or higher (Rank E or lower does not exist). Became.

In addition, in Examples 1 and 12 to 18 (50≦C ² /F≦100), all the solid carrier adhesion (200,000 sheets) was Rank A (no Rank B or less). Among them, in Examples 12, 13, 17 and 18 (45≦C ² /F≦100), the background stain (100,000 sheets) was Rank C or more (no Rank D or less).

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to these embodiments, and various modifications and changes are made within the scope of the invention described in the claims. Is possible.

1 Carrier 3 Core Particle 7 Fine Particle 9 Fluororesin Container 11, 13 Electrode 15 Sample 17 Process Cartridge 19 Photoreceptor 21 Charging Means 23 Developing Means 25 Transfer Means

Japanese Patent No. 5473642 JP, 2014-115463, A

Claims (10)

A carrier having a magnetic core particle and a coating layer for coating the surface of the core particle,
The coating layer contains a resin and tungsten-doped tin oxide as fine particles,
The particle size distribution of the fine particles has at least two peaks,
When the particle size showing the peak having the largest particle size among the peaks is anm and the particle size showing the peak having the smallest particle size is bnm, a and b are 5≦a/b≦100. And the BET specific surface area of the carrier is C and the BET specific surface area of the core particle is F, the C and F satisfy 20≦C ² /F≦280.   The carrier according to claim 1, wherein a satisfies 400≦a≦1800.   The carrier according to claim 1, wherein the F satisfies 0.05≦F≦0.2. The core particles are of iron, at least one magnetic body selected from the Ma Gunetaito, hematite and ferrite, in which an alloy including a magnetic body, or a magnetic body is dispersed in a resin, according to claim 1 to 3 The carrier according to any one of items. The resin has the general formula

(In the formula, R ¹ is a hydrogen atom or a methyl group, m is an integer of 1 to 8, R ² is an aliphatic hydrocarbon group having 1 to 4 carbon atoms, and R ² may be the same or different. May be present, and X=10 to 90 mol %.)
A structural unit represented by or a general formula

(In the formula, R ¹ is a hydrogen atom or a methyl group, m is an integer of 1 to 8, R ² is an aliphatic hydrocarbon group having 1 to 4 carbon atoms, and R ³ is alkyl having 1 to 8 carbon atoms. Group or an alkoxy group having 1 to 4 carbon atoms, Y=10 to 90 mol %.)
The carrier according to any one of claims 1 to 4, which has a structural unit represented by:   A developer containing the carrier according to any one of claims 1 to 5 and a toner.   The developer according to claim 6, wherein the content of the toner is 2 to 50 mass% with respect to 1 mass% of the carrier. A process cartridge using the developer according to claim 6 or 7,
A photoconductor,
A process cartridge comprising: a developing unit that develops the electrostatic latent image formed on the photoconductor with the developer to form a toner image on the photoconductor. An image forming apparatus using the developer according to claim 6 or 7,
A photoconductor,
Charging means for charging the photoreceptor,
Exposure means for forming an electrostatic latent image on the photoreceptor,
Developing means for developing the electrostatic latent image formed on the photoconductor with the developer to form a toner image on the photoconductor;
Transfer means for transferring the toner image onto a recording medium,
An image forming apparatus comprising: a fixing unit configured to fix the toner image on the recording medium. An image forming method using the developer according to claim 6 or 7,
A step of forming an electrostatic latent image on the photoreceptor,
Developing the electrostatic latent image formed on the photoconductor with the developer to form a toner image on the photoconductor;
Transferring the toner image to a recording medium,
And a step of fixing the toner image on the recording medium.

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