JP2012078737A - Developer, manufacturing method of developer, image forming unit, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide highly environmentally-friendly toner that uses a raw material derived from plants being in less demand as an edible plant, and has excellent releasability, as well as a manufacturing method of the toner.SOLUTION: Toner includes a binder resin, colorant, a mold release agent, and a polylactic acid. The mold release agent includes a ester component extracted from sunflower seeds. Toner is manufactured by allowing O/W suspension into which a binder monomer, sunflower wax, a polylactic acid, a charge control agent, colorant, and initiator are mixed and dispersed to be subjected to polymerization reaction, and then granulating the reaction product.

Description

  The present invention relates to a developer that makes an electrostatic image visible, a method for producing the same, and an image forming technique using the developer, and more particularly, to an electrostatic image formed on a photoreceptor in an image forming process using an electrophotographic method. The present invention relates to a developer to be actualized, a method for producing the same, and an image forming technique using the developer.

  An electrophotographic image forming process includes a charging process for forming a uniform charge on the surface of the photoconductor, an exposure process for forming an electrostatic charge image (electrostatic latent image) by irradiating light on the surface of the photoconductor, and charging. A developing process in which the developed developer (toner) is attached to the electrostatic image to form a toner image on the photoreceptor, a transfer process in which the toner image is transferred to a recording medium such as paper, and the transferred toner image is recorded. It consists of a series of processes such as a fixing process for fixing to a medium. Such an image forming process is disclosed in, for example, Japanese Patent Application Laid-Open No. 2004-341122 (Patent Document 1).

  The developer used in the image forming process generally contains a binder resin (binder resin) constituting a base material particle having a particle size of several μm to several tens of μm and a colorant such as a pigment, and is further necessary. Accordingly, it contains a release agent (wax) for improving offset resistance and an external additive such as silica for adhering to the surface of the base material particles to modify the surface structure. Such a method for producing a developer can be roughly classified into a pulverization method in which a developer is granulated and a polymerization method in which the developer is granulated in a wet method. As the polymerization method, a turbid polymerization method and an emulsion polymerization method are widely known. As prior art documents relating to the pulverization method, for example, JP-A-2000-75543 (Patent Document 2) is cited, and as prior art documents relating to the polymerization method, for example, JP-A-63-186253 (Patent Document 3). ).

  2. Description of the Related Art In recent years, in an image forming apparatus (such as a copying machine, a printer, or a facsimile machine) using an electrophotographic method, the speed of image formation and the high definition of an image have progressed. As a characteristic required for a developer, for high definition, it is required to make the base material particle smaller. However, if the particle size is reduced, a similar image can be obtained unless the weight ratio of the colorant in the developer is increased. The concentration cannot be ensured. Therefore, at the same time as increasing the amount of the colorant contained in each base material particle, the variation in the content of the colorant between the base material particles is suppressed, and the colorants are not aggregated in the base material particles, and are uniform. Are required to be dispersed.

  In the pulverization method, a binder resin, a colorant, and a release agent are melted and kneaded, and pulverized and classified to generate a developer. However, as the developer has a smaller particle size for higher image definition, more energy is required at the time of pulverization, so that there is a problem that production efficiency is lowered and manufacturing cost is increased. Further, since the kneaded material composed of the binder resin, the colorant, and the release agent is pulverized by the mechanical impact force, the colorant and the release agent are easily exposed on the surface of the developer. When a certain colorant is exposed on the surface of the developer and pulverized, the result of a mutagenicity test (a simple test for determining the presence or absence of carcinogenicity) may be a problem. Further, when the release agent is exposed on the surface of the developer, there is a problem that a phenomenon called filming that is detached from the base material particles and is fixed to a member such as a photoreceptor is likely to occur.

  On the other hand, in the suspension polymerization method, a dispersed phase containing a polymerizable monomer, a colorant, a release agent, and the like is put into an aqueous suspension stabilizer that is a continuous phase, and after high-speed stirring, polymerization is performed. In this method, a developer is generated by performing an operation. In the emulsion polymerization method, a dispersed phase containing a polymerizable monomer, a colorant, a release agent and the like is added to an emulsifier (surfactant), and the polymerizable monomer is subjected to emulsion polymerization to produce primary particles. In this method, the developer is produced by aggregating and associating these primary particles. Such a polymerization method has an advantage that the above-mentioned filming hardly occurs because it is easy to encapsulate the release agent and the colorant in the base material particles.

JP 2004-341122 A JP 2000-75543 A JP-A 63-186253

  In recent years, companies have been focusing on developing highly environmental developers, and in particular, focusing on the selection of plant-derived raw materials and development of developers using these, de-oiling and releasing carbon dioxide into the atmosphere. Aims to reduce the amount. However, even if it is a plant-derived raw material, edible plants such as corn and sugarcane will cause a rise in food prices, so there is a problem in terms of morality. Therefore, it is required that the demand for food is low. In addition, it is necessary to have sufficient characteristics required as a developer while being a highly environmental developer.

  In view of the above, an object of the present invention is to use a developer derived from a plant whose demand as an edible plant is low, and a developer having good releasability, a method for producing the same, an image forming unit using the developer, and an image It is in providing a forming apparatus.

  The developer according to the present invention is a developer that reveals an electrostatic charge image, and includes a binder resin, a colorant, and a release agent, and the release agent includes an ester component extracted from sunflower seeds. It is characterized by that.

  The method for producing a developer according to the present invention includes a step of mixing a polymerizable monomer, a colorant and a release agent to form a polymerizable monomer composition, and granulating the polymerizable monomer composition. And the release agent contains an ester component extracted from sunflower seeds.

  An image forming unit according to the present invention includes a container in which the developer is accommodated, and a developer supply unit that forms the developer image by supplying the developer to an electrostatic charge image.

  An image forming apparatus according to the present invention includes: the image forming unit; and a transfer unit that transfers a developer image formed by the image forming unit to a surface of a recording medium.

  According to the present invention, it is possible to provide a developer having good releasability while using a release agent made of a plant-derived raw material, and an image forming technique using the same.

1 is a diagram schematically showing a configuration of an image forming apparatus according to an embodiment of the present invention. It is a figure which shows roughly an example of the basic structure of the image forming unit of this Embodiment. It is a figure which shows the cross-sectional TEM image of the toner particle of the Example which concerns on this invention. It is a table | surface which shows the evaluation result of the developer of an Example and a comparative example.

  Hereinafter, various embodiments according to the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram schematically showing a configuration of an image forming apparatus 100 according to an embodiment of the present invention. The image forming apparatus 100 includes a tray 18 in which a recording medium 12 is stored in a housing 101, and image forming units 4K, 4Y, 4M, and 4C that form toner images (developer images) on the recording medium 12. The image forming apparatus includes a fixing unit 17 that fixes the toner image on the recording medium 12, and a conveyance mechanism that conveys the recording medium 12 along the conveyance path 12R. The transport mechanism includes transport rollers 20, 21A, 21B, a transfer belt 13, drive rollers 15A, 15B, and discharge rollers 22A, 22B.

  The recording medium 12 accommodated in the tray 18 is taken out from the tray 18 one by one by the hopping roller 19 and then conveyed onto the transfer belt 13 by the conveying rollers 20, 21 </ b> A, 21 </ b> B. The driving rollers 15A and 15B drive the transfer belt 13, whereby the transfer belt 13 sequentially passes the recording medium 12 through the image forming units 4K, 4Y, 4M, and 4C and then sends the recording medium 12 to the fixing unit 17.

  The image forming units 4K, 4Y, 4M, and 4C are sequentially arranged from the upstream side to the downstream side along the conveyance path 12R of the recording medium 12 that is the transfer material. Each of the image forming units 4K, 4Y, 4M, and 4C has a function of executing a charging process, an exposure process, a developing process, and a transfer process. Each of these image forming units 4K, 4Y, 4M, and 4C has photosensitive drums 1K, 1Y, 1M, and 1C and cartridges 8K, 8Y, 8M, and 8C, and the cartridges 8K, 8Y, 8M, and 8C. The developer (toner particles) 9K, 9Y, 9M, and 9C each containing black, yellow, magenta, and cyan colorants and a binder resin are accommodated therein.

  The basic structures of the image forming units 4K, 4Y, 4M, and 4C are the same. FIG. 2 is a diagram schematically showing a basic structure of the image forming unit 4 representing one of the image forming units 4K, 4Y, 4M, and 4C. The photosensitive drum 1 (any one of the photosensitive drums 1K, 1Y, 1M, and 1C) is configured by forming a photoconductive layer around a conductive base such as an aluminum pipe, for example. For the photoconductive layer, an organic photoconductor (OPC) or amorphous silicon can be used.

  The charging unit 2 has a function of uniformly charging the surface of the photosensitive drum 1. As shown in FIG. 2, the charging unit 2 according to the present embodiment includes a metal shaft 2S and a semiconductive rubber layer 2C formed around the metal shaft 2S. The charging unit 2 can uniformly charge the surface of the charging unit 2 by contacting the surface of the photosensitive drum 1 while rotating in the direction opposite to the rotating direction of the photosensitive drum 1.

  The exposure unit 3 forms an electrostatic charge image (electrostatic latent image) on the surface of the photosensitive drum 1 by irradiating the surface of the photosensitive drum 1 with light based on image information to erase the charged charges. The exposure unit 3 includes, for example, a plurality of LED elements (light emitting diode elements), an LED driving unit that drives these LED elements, and a lens array that guides the emitted light of the LED elements to the surface of the photosensitive drum 1. Can do.

  The developing roller 7 has a developing function of making an electrostatic image appear by attaching a charged developer 9 (any one of the developers 9K, 9Y, 9M, and 9C) to the electrostatic image on the photosensitive drum 1. As shown in FIG. 2, the developing roller 7 of the present embodiment includes a metal shaft 7S, and a semiconductive resin layer (for example, a semiconductive urethane rubber layer) 7C formed around the metal shaft 7S. However, the present invention is not limited to this. The developing roller 7 is disposed so as to contact the surface of the photosensitive drum 1.

  The supply roller 10 has a function of supplying the developer 9 contained in the cartridge 8 (any one of the cartridges 8K, 8Y, 8M, and 8C) to the developing roller 7 while sliding with the developing roller 7. As shown in FIG. 2, the supply roller 10 of the present embodiment includes a metal shaft 10S and a resin layer (silicon rubber layer or the like) formed around the metal shaft 10S. It is not limited to. The developing blade 11 is a member that regulates the developer layer adhering to the developing roller 7 and makes the thickness of the developer layer on the surface of the developing roller 7 uniform. The developing blade 11 can be composed of a plate-like member such as stainless steel, for example. A potential difference is applied between the surface of the supply roller 10 and the surface of the developing roller 7, and the developer 9 adheres to the surface of the developing roller 7 by this potential difference to form a developer layer. The developer layer is thinned to a specified thickness by the developing blade 11 as the developing roller 7 rotates, and then conveyed to the developing region where the photosensitive drum 1 and the developing roller 7 are in contact with each other. In this developing region, the developer 9 having a thin layer on the developing roller 7 is adsorbed to the electrostatic charge image on the photosensitive drum 1 to form a developer image.

  The transfer roller 14 is a member that transfers (moves) the developer image on the photosensitive drum 1 to the recording medium 12 in the transfer unit 5. The transfer roller 14 has a surface layer made of, for example, a foaming elastic body, and is disposed so as to apply pressure to the surface of the photosensitive drum 1 via the transfer belt 13.

  The cleaning member 6 is a member that collects the developer 9 remaining on the surface of the photosensitive drum 1 after the developer image is transferred to the recording medium 12. As shown in FIG. 2, the cleaning member 6 according to the present embodiment is made of a resinous plate-like member such as urethane rubber, and is arranged so that the front end thereof is in pressure contact with the surface of the photosensitive drum 1. However, the present invention is not limited to this. A cleaning roller may be used instead of the plate-like member.

  After the developer images are transferred to the recording medium 12 in the image forming units 4K, 4Y, 4M, and 4C in FIG. 1, the recording medium 12 is conveyed to the fixing unit 17, respectively. The fixing unit 17 includes a backup roller (pressure roller) 17A and a heat roller 17B. The backup roller 17A and the heat roller 17B melt and fix the developer image on the recording medium 12 to the recording medium 12 with heat and pressure. Thereafter, the recording medium 12 is discharged to the outside by the discharge rollers 22A and 22B.

  In the fixing unit 17, when the surface temperature of the heat roller 17B is too low, the developer on the recording medium 12 is not sufficiently melted, and a part of the developer near the surface of the heat roller 17B is melted, and the heat roll 17B is melted. The phenomenon of adhesion (cold offset) may occur. On the other hand, when the surface temperature of the heat roll 17B is too high, the developer on the recording medium 12 is excessively melted, so that the viscosity of the developer is greatly reduced, and thereby a part of the developer is fixed on the recording medium 12. In some cases, a phenomenon (hot offset) occurs that cannot be performed and adheres to the heat roll 17B. Even if cold offset or hot offset occurs, an image having a non-uniform density is formed. However, by uniformly dispersing the release agent in the binder resin constituting the developer 9, a cold offset or hot offset is formed. Resistance to offset (offset resistance performance) can be improved.

式（１）中、ｍは、２１〜３１の範囲内の整数であり、ｎは、１４〜２８の範囲内の整数である。ここで、ｎ≦２８且つｍ≦３１であるので、離型剤の融点が高くなり過ぎず、コールドオフセットの発生を効果的に抑制することができる。また、ｎ≧１４且つｍ≧２１であるので、離型剤のうちの低分子量成分の割合が抑制されて画像形成時のダストの発生を抑制することができる。 Next, the developer 9 according to the present embodiment will be described. The developer 9 is polymerized toner particles produced by a suspension polymerization method using an aqueous suspension stabilizer as a continuous phase. Specifically, first, a polymerizable monomer, a colorant, and a release agent are mixed to produce a polymerizable monomer composition. Here, a charge control agent may be mixed as necessary. As the release agent (wax), one having as a main component an ester component represented by the following general formula (1) extracted from sunflower seeds is used.

In formula (1), m is an integer in the range of 21 to 31 and n is an integer in the range of 14 to 28. Here, since n ≦ 28 and m ≦ 31, the melting point of the release agent does not become too high, and the occurrence of cold offset can be effectively suppressed. Further, since n ≧ 14 and m ≧ 21, the ratio of the low molecular weight component in the release agent is suppressed, and the generation of dust during image formation can be suppressed.

  The mold release agent having such an ester component is, for example, a method in which oil is extracted from sunflower seeds using a squeezer and then impurities are removed from the remaining straw using a decolorizer. It can be purified by distillation.

  Moreover, when producing | generating a polymerizable monomer composition, it is desirable to mix a plant-derived polymer component with a polymerizable monomer, a coloring agent, and a mold release agent. By mixing the plant-derived polymer component, the proportion of the plant-derived component in the developer 9 is increased, so that the developer 9 having higher environmental properties can be generated.

式（２）中、ｋは、繰り返し単位数を表す２以上の整数である。 Examples of the plant-derived polymer component include polylactic acid, polyglycolic acid, polybutylene succinate or vanillin-derived polyester. From the viewpoint of easy availability, the following general formula (2) It is preferable to mix the polylactic acid represented.

In formula (2), k is an integer of 2 or more representing the number of repeating units.

  After producing the above polymerizable monomer composition, the polymerizable monomer composition is added to the suspension stabilizer to form a dispersed phase. Thereafter, a polymerization initiator, a crosslinking agent and a chain transfer agent are added to this dispersed phase, and then the dispersed phase is stirred at a high speed to granulate a polymerizable monomer composition. After the granulation, the polymerizable monomer is polymerized by changing the temperature conditions and stirring the dispersed phase at a low speed. Thereafter, by dehydrating the polymer slurry, polymer toner particles having a particle diameter of about several μm to several tens of μm and a narrow particle size distribution can be obtained.

  The weight ratio of the release agent in the polymerized toner particles thus produced is 1% by weight to 8% by weight, particularly 4% by weight to 8% by weight from the viewpoint of securing the anti-offset performance. preferable.

  As the binder resin, a thermoplastic resin such as a vinyl resin is desirable. Examples of the polymerizable monomer that is a precursor of the vinyl resin include styrene, 2,4-dimethylstyrene, α-methylstyrene, p-ethylstyrene, o-methylstyrene, m-methylstyrene, and p-methylstyrene. , Styrene or styrene derivatives such as p-chlorostyrene and vinylnaphthalene, or 2-ethylhexyl acrylate, methyl methacrylate, acrylic acid, methyl acrylate, ethyl acrylate, -n-propyl acrylate, isobutyl acrylate, acrylic Acid-t-butyl, amyl acrylate, cyclohexyl acrylate, -n-octyl acrylate, isooctyl acrylate, decyl acrylate, lauryl acrylate, stearyl acrylate, methoxyethyl acrylate, 2-hydroxyethyl acrylate, acrylic Glycidyl, phenyl acrylate, methyl α-chloroacrylate, methacrylic acid, ethyl methacrylate, -n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, methacryl Amyl acid, cyclohexyl methacrylate, -n-octyl methacrylate, isooctyl methacrylate, decyl methacrylate, uraryl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, methoxyethyl methacrylate, 2-hydroxyethyl methacrylate, Ethylenic monocarboxylic acids and esters thereof such as glycidyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, or ethylene, Ethylenically unsaturated monoolefins such as propylene, butylene and isobutylene, or vinyl esters such as vinyl chloride, vinyl bromoacetate, vinyl propionate, vinyl formate and vinyl caproate, or ethylene such as acrylonitrile, methacrylonitrile and acrylamide For example, an ethylenic dicarboxylic acid such as a maleic acid ester or a maleic acid ester and a substituent thereof, for example, vinyl ketones such as vinyl methyl ketone, or vinyl ethers such as vinyl methyl ether.

  As the colorant, known pigments or dyes corresponding to black, yellow, magenta and cyan may be used, and are not particularly limited. Carbon black is suitable as the black colorant. Examples of yellow colorants include C.I. I. Pigment Yellow 74 may be C.I. as a magenta colorant. I. As the pigment red 238 and a cyan colorant, phthalocyanine pigments such as pigment blue 15: 3 can be used.

  Examples of the polymerization initiator include 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1′-azobis (cyclohexane-1-carbonitrile). An azo polymerization initiator such as 2,2′-azobis-4-methoxy-2,4-dimethylvaleronitrile can be used.

  Examples of the crosslinking agent include divinylbenzene, divinylnaphthalene, polyethylene glycol dimethacrylate, 2,2-bis (4-methacryloxydiethoxydiphenyl) propane, and 2,2-bis (4-acryloxydiethoxydiphenyl). Propane, diethylene glycol diacrylate, triethylene glycol diacrylate, 1,3-butylene glycol glycol dimethacrylate, 1,6-hexylene glycol dimethacrylate, neopentyl glycol dimethacrylate, dipropylene glycol dimethacrylate, polypropylene glycol dimethacrylate, tri Use methylolpropane trimethacrylate, trimethylolpropane triacrylate, or tetramethylolmethane tetraacrylate. Can.

  As described above, in the present embodiment, sunflower, which is low in demand as an edible plant, is adopted as a plant-derived material, and polymerized toner particles containing a release agent (wax) extracted from the sunflower seeds are used as a developer. Since it is used, it is possible to provide a developer that does not cause food problems, can suppress the use of petroleum-derived raw materials, and can reduce carbon dioxide emissions. In addition, it is possible to provide a developer that suppresses the occurrence of filming and has high anti-offset performance.

  Next, various examples of the developer 9 will be described, but these examples do not limit the present invention. Hereinafter, the unit “part” means “part by weight”.

Example 1
First, 110 parts of trisodium phosphate was mixed with 3350 parts of pure water and sufficiently dissolved at a liquid temperature of 60 ° C., and then a calcium chloride aqueous solution in which 70 parts of calcium chloride was dissolved in 440 parts of pure water was added. A continuous phase was produced by high-speed stirring for 30 minutes while keeping the liquid temperature at 60 ° C. at 4300 rpm (manufactured by Primics Co., Ltd.).

  On the other hand, 300 parts of styrene monomer, 34 parts of carbon black, and 6 parts of a dispersant were charged into a bead mill disperser (manufactured by Nippon Coke Industries Co., Ltd.) and dispersed for 120 minutes at 3200 rpm to produce a carbon black dispersion. . After the dispersion is completed, the carbon black dispersion is sufficiently stirred with a homodisper (Primics Co., Ltd.) at 1800 rpm for 50 minutes while maintaining the temperature at 55 ° C. for 50 minutes. At that time, the release agent (wax) generated from sunflower seeds as a release agent was contained in the carbon black dispersion.

Carbon black dispersion 345 parts Styrene monomer 91 parts Butyl acrylate 108 parts Charge control resin 19 parts Charge control agent (metal salicylate complex) 2 parts Sunflower wax (melting point: 77 ° C) 57 parts

  After completion of the dispersion phase stirring, a mixed solution prepared by dissolving 16 parts of dimethyl 2,2'-azobis in 47 parts of styrene monomer, 1 part of divinylbenzene, and 3 parts of mercaptopropionate (chain transfer agent) are added to the dispersion phase. Then, the mixture is sufficiently stirred at 1400 revolutions / minute for 5 minutes with a homodisper (manufactured by PRIMIX Corporation). After completion of the dispersion phase stirring, the dispersion phase was added to the previously produced continuous phase and granulated at 60 ° C. with a Neomixer (manufactured by Primemix Co., Ltd.) at 3800 rpm. Next, the dispersed phase after granulation was subjected to a polymerization reaction by stirring at a low speed at 80 ° C. for 8 hours at 100 rpm with a special paddle blade (manufactured by Satake Chemical Machinery Co., Ltd.).

  After the polymerization, tricalcium phosphate in the polymer slurry was dissolved with nitric acid and then dehydrated to prepare a cake. The cake was pulverized to a particle having an appropriate size with a pulverizer (manufactured by Tokuju Kogaku Co., Ltd.), dried, and silica was added as an external additive to produce the developer of Example 1.

  The cross section of the polymerized toner particles of the developer was observed with a transmission electron microscope (TEM). FIG. 3 is a diagram showing a cross-sectional TEM image of the polymerized toner particles of Example 1. As shown in FIG. 3, the polymerized toner particles 30 in which the release agent (wax) 31 was completely encapsulated in the binder resin could be observed.

  Further, when the melting characteristics of the polymerized toner particles 30 were measured, Tg (glass transition temperature): 59 ° C., Ts (softening temperature): 73.3 ° C., Tfb (outflow start temperature): 104.8 ° C., T1 / 2 It became 149.7 degreeC. Here, “T1 / 2” means the melting temperature (softening point) in the 1/2 method.

  As for fixability, the cold offset generation temperature was less than 180 ° C., the hot offset generation temperature was 215 ° C. or more (fixing range: 180 to 215 ° C.), and good fixing performance was confirmed.

  Further, the melting characteristics of the polymerized toner particles of Example 1 were measured using a flow tester (“CFT-500D” manufactured by Shimadzu Corporation). The fixability of the produced polymer toner particles was evaluated by a printer “B4500n” manufactured by Oki Data Corporation. For fixing property evaluation, cold offset temperature: 180 ° C. or lower is “◯”, 181 ° C. or higher and 185 ° C. or lower is “Δ”, 186 ° C. or higher is “X”, hot offset temperature: 215 ° C. or higher is “◯”, 205 ° C. or more and 214 ° C. or less was judged as “Δ”, and less than 205 ° C. was judged as “×”. The evaluation results are shown in the table of FIG.

  From the above experimental results, it is found that the fixability is good even with a developer containing a release agent (wax) generated from sunflower seeds as a plant-derived depetroleum material at a weight ratio of at least 8 wt%. confirmed.

(Example 2)
First, 110 parts of trisodium phosphate was mixed with 3350 parts of pure water and sufficiently dissolved at a liquid temperature of 60 ° C., and then a calcium chloride aqueous solution in which 70 parts of calcium chloride was dissolved in 440 parts of pure water was added. A continuous phase was produced by high-speed stirring for 30 minutes while keeping the liquid temperature at 60 ° C. at 4300 rpm (manufactured by Primics Co., Ltd.).

  On the other hand, 300 parts of styrene monomer, 34 parts of carbon black, and 6 parts of a dispersant were charged into a bead mill disperser (manufactured by Nippon Coke Industries Co., Ltd.) and dispersed for 120 minutes at 3200 rpm to produce a carbon black dispersion. . After the dispersion was completed, the carbon black dispersion liquid was sufficiently agitated with a homodisper (manufactured by Primics Co., Ltd.) at 1800 rpm for 50 minutes while maintaining the temperature at 55 ° C. At that time, the carbon black dispersion contained the release agent (wax) produced from sunflower seeds as a release agent and the polylactic acid as a binder resin component.

Carbon black dispersion 345 parts Styrene monomer 91 parts Butyl acrylate 51 parts Charge control resin 19 parts Charge control agent (salicylic acid metal complex) 2 parts Sunflower wax (melting point: 77 ° C) 57 parts Polylactic acid (Tg: 50 ° C) 57 parts

  After completion of the dispersion phase stirring, a mixed solution prepared by dissolving 16 parts of dimethyl 2,2'-azobis in 47 parts of styrene monomer, 1 part of divinylbenzene, and 3 parts of mercaptopropionate (chain transfer agent) are added to the dispersion phase. Then, the mixture was sufficiently stirred at 1400 rpm for 5 minutes with a homodisper (manufactured by PRIMIX Corporation). After completion of the dispersion phase stirring, the dispersion phase was added to the previously produced continuous phase and granulated at 60 ° C. with a Neomixer (manufactured by Primemix Co., Ltd.) at 3800 rpm. Next, the dispersed phase after granulation was subjected to a polymerization reaction by stirring at a low speed at 80 ° C. for 8 hours at 100 rpm with a special paddle blade (manufactured by Satake Chemical Machinery Co., Ltd.).

  After the polymerization, tricalcium phosphate in the polymer slurry was dissolved with nitric acid and then dehydrated to prepare a cake. The cake was pulverized to a particle having an appropriate size with a pulverizer (manufactured by Tokuju Kogaku Co., Ltd.), dried, and silica was added as an external additive to produce the developer of Example 2.

  When the melting characteristics of this developer were measured, they were Tg: 60 ° C., Ts: 73.8 ° C., Tfb: 105.1 ° C., and T1 / 2: 145.0 ° C. Further, it was confirmed that the fixing property showed a good fixing performance with a cold offset generation temperature of less than 180 ° C. and a hot offset generation temperature of 215 ° C. or more.

  Further, when the fixability of the developer of Example 2 was evaluated, the cold offset generation temperature was less than 180 ° C., the hot offset generation temperature was 215 ° C. or more (fixing range: 180 to 215 ° C.), and good fixing performance was obtained. confirmed. The experimental results of the developer of Example 2 are shown in the table of FIG.

(Comparative Example 1)
The developer of Comparative Example 1 was produced under the same conditions as in Example 1 except that paraffin wax (melting point: 68 ° C.) was used as a release agent. When the melting characteristics of this developer were measured, they were Tg: 60 ° C., Ts: 71 ° C., Tfb: 100.1 ° C., and T1 / 2: 142.6 ° C.

  Further, regarding the fixability, the cold offset occurrence temperature was 185 ° C. or less, and the hot offset occurrence temperature was 215 ° C. or more (fixing range: 185 to 215 ° C.). Therefore, the cold offset margin is reduced as compared with the first and second embodiments. The experimental results of the developer of Comparative Example 1 are shown in the table of FIG.

  DESCRIPTION OF SYMBOLS 100 Image forming apparatus, 1,1C, 1M, 1Y, 1K Photosensitive drum, 2 Charging part, 3 Exposure part, 4,4C, 4M, 4Y, 4K Image forming unit, 5 Transfer part, 6 Cleaning member, 7 Developing roller 8, 8C, 8M, 8Y, 8K cartridge, 9, 9C, 9M, 9Y, 9K developer (toner), 10 supply roller, 11 developing blade, 12 recording medium, 13 transfer belt, 14, 14C, 14M, 14Y , 14K transfer roller, 15A, 15B transport roller, 17 fixing unit, 30 developer, 31 release agent.

Claims (14)

A developer that reveals an electrostatic image,
Contains binder resin, colorant and release agent,
The developer, wherein the release agent contains an ester component extracted from sunflower seeds. The developer according to claim 1, wherein the ester component is

A developer represented by the general formula: wherein m is an integer in the range of 21 to 31 and n is an integer in the range of 14 to 28.   3. The developer according to claim 1, wherein the content of the release agent is in the range of 1 wt% to 8 wt%.   4. The developer according to claim 1, wherein the binder resin contains a plant-derived polymer component. 5. 5. The developer according to claim 4, wherein the plant-derived polymer component is

A developer, characterized in that it is a polylactic acid represented by the general formula (k is an integer of 2 or more representing the number of repeating units).   6. The developer according to claim 5, wherein the polylactic acid content is in the range of 1% by weight to 8% by weight.   The developer according to any one of claims 1 to 6, wherein a polymerizable monomer composition obtained by mixing the binder resin precursor, the colorant, and the release agent is granulated. A developer characterized by being produced by polymerization. A step of mixing a polymerizable monomer, a colorant and a release agent to produce a polymerizable monomer composition;
Granulating the polymerizable monomer composition;
With
The method for producing a developer, wherein the releasing agent contains an ester component extracted from sunflower seeds. The method for producing a developer according to claim 8, wherein the ester component is

(M is an integer in the range of 21 to 31 and n is an integer in the range of 14 to 28). A method for producing a developer according to claim 8 or 9, wherein
Preparing an aqueous dispersion stabilizer as a continuous phase;
Adding the polymerizable monomer composition to the continuous phase to form a dispersed phase;
Granulating and polymerizing the polymerizable monomer composition in the dispersed phase; and
A method for producing a developer, comprising:   The method for producing a developer according to claim 10, wherein in the step of forming the dispersed phase, a plant-derived polymer component is added to the continuous phase. The method for producing a developer according to claim 11, wherein the plant-derived polymer component is:

A method for producing a developer, which is polylactic acid represented by the general formula (k is an integer of 2 or more representing the number of repeating units): A container containing the developer according to any one of claims 1 to 7,
Developer supplying means for supplying the developer to an electrostatic charge image to form a developer image;
An image forming unit comprising: An image forming unit according to claim 13;
A transfer unit for transferring the developer image formed by the image forming unit to the surface of the recording medium;
An image forming apparatus comprising:

Images