JP5119052B2 - Toner manufacturing method, toner, developer, developing device, and image forming apparatus - Google Patents

Description

  The present invention relates to a toner production method and toner used for developing a latent image on the surface of an image forming body in an image forming apparatus such as an electrophotographic system or an electrostatic printing system, a developer containing the toner, and the developer. The present invention relates to a developing device and an image forming apparatus to be used.

  The toner that visualizes the latent image is used in various image forming processes. For example, the toner is used in an electrophotographic image forming process.

  In an image forming apparatus using an electrophotographic image forming process, for example, a charging process for uniformly charging a photosensitive layer on the surface of a photosensitive drum as a latent image forming body, and an original image on the surface of the photosensitive drum in a charged state The exposure process for projecting the signal light to form an electrostatic latent image, the developing process for supplying the electrophotographic toner to the electrostatic latent image on the surface of the photosensitive drum to make it visible, and the media such as paper and OHP sheet The transfer process for transferring the toner image on the surface of the photosensitive drum, the fixing process for fixing the toner image on the medium by heating and pressurizing, and the toner remaining on the surface of the photosensitive drum after the toner image transfer are removed by a cleaning blade. Then, a cleaning process for cleaning the surface of the photosensitive drum is executed to form a desired image on the medium. Transfer of the toner image to the medium may be performed via an intermediate transfer medium.

  For example, the toner for electrophotography is composed mainly of a binder resin and a colorant, and if necessary, a toner material mixed by adding a release agent, a charge control agent, and the like is melt-kneaded and cooled to solidify. Thereafter, a kneading and pulverizing method for pulverizing and classifying, or a polymerization method represented by a suspension polymerization method, an emulsion polymerization aggregation method, and the like are obtained.

  In recent years, many efforts have been made in various fields from the viewpoint of global environmental conservation, and one of them is to reduce the environmental load by reducing waste. At present, many raw materials for products are manufactured from petroleum, reducing the amount of heat required when manufacturing raw materials manufactured from petroleum, and the CO2 generated during the incineration of products manufactured from such raw materials. It is important to reduce carbon and the like from the viewpoint of suppressing global warming.

  Therefore, the use of plant-derived resources called biomass has attracted a great deal of attention as a new initiative that helps prevent global warming. Carbon dioxide generated when biomass is burned is carbon dioxide in the atmosphere originally taken by plants through photosynthesis, so the overall balance of carbon dioxide in the atmosphere is zero and the total amount does not change. In this way, the property that does not affect the increase or decrease of carbon dioxide in the atmosphere is called carbon neutral, and it is possible to fix the amount of carbon dioxide in the atmosphere by using plant-derived raw materials that are carbon neutral. it can. Plastics made from such biomass are called by various names such as biomass resin, biomass polymer, biomass plastic, and non-petroleum polymer materials, and these raw materials are called biomass monomers. .

  Also in the field of electrophotography, as environmentally friendly efforts, specifically, environmental safety, waste reduction, energy saving, etc. have been promoted, and the use of binder resins containing biomass has been proposed. However, since the biomass polymer is highly hydrolyzable, the toner containing the biomass polymer has poor stability over time, and there is a problem that it is difficult to maintain the initial performance. In a high-temperature and high-humidity environment, hydrolysis of the biomass polymer is particularly remarkable.

  In order to solve such a problem, in Patent Document 1, a part or substantially all of the carboxyl group terminal of the aliphatic polyester is blocked with a monocarbodiimide compound having a 5% weight loss temperature of 170 ° C. or higher. An aliphatic polyester resin having a sufficiently high molecular weight, high hydrolysis resistance, and heat resistance for practical use is disclosed.

  Energy saving has also been studied from various angles. In the field of electrophotography, it is effective to reduce the fixing energy by lowering the temperature at which the toner is fixed in the fixing process. Is required to have a low melting point. In order to lower the melting point of the toner, the design of the binder resin contained in the toner is particularly important. In addition, lowering the melting point of toner is indispensable in the trend related to higher speed copying machines and facsimiles.

  Examples of a method for fixing toner transferred onto a medium such as paper and an OHP sheet include a fixing method using a contact heating type fixing device represented by a heat roll. The fixing property of the toner in this fixing method can be expressed by the width of the non-fixing area of the fixing from the temperature at which the low temperature offset occurs to the temperature at which the high temperature offset occurs. This is to lower the temperature and is also called low temperature fixing.

  Patent Document 2 discloses a toner for electrophotography suitable for a contact heating method, which uses a polycarbodiimide resin as a carbodiimide compound, can be fixed at a lower temperature, has excellent fixability, and has a wide fixing non-offset region. ing.

JP 2001-261797 A JP 2000-35693 A

  The aliphatic polyester resin disclosed in Patent Document 1 in which the carboxyl group terminal contained in the resin is blocked by the monocarbodiimide compound blocks the carboxyl group terminal by the monocarbodiimide compound, so that the resin cannot be crosslinked, and the high temperature offset The generation temperature is lowered, and it is impossible to combine the suppression of hydrolyzability by end-capping and the improvement of fixability.

  Examples of the binder resin that satisfies the requirements for the toner include a resin having a crosslinked structure, and a resin composed of a high molecular weight body and a low molecular weight body. In order to improve the high temperature offset resistance of the toner, a crosslinking component is used. Alternatively, when the ratio of the high molecular weight is increased, the melt viscosity of the resin increases and the low-temperature fixability of the toner becomes insufficient. Further, if the ratio of the low molecular weight substance is increased in order to improve the low temperature fixability, the melt viscosity of the resin is lowered, but the elasticity of the toner is lowered and the high temperature offset resistance is lowered. In order to lower the melting point of the toner and maintain the offset resistance at high temperature, that is, to obtain the optimal molecular weight distribution for low-temperature fixing, the blending balance of the high molecular weight body and the low molecular weight body is important.

  However, the electrophotographic toner disclosed in Patent Document 2 has unclear effects on resin physical properties due to cross-linking, and depending on the amount added, the balance of the molecular weight of the resin may change, and the low-temperature fixability may deteriorate. .

  An object of the present invention is to provide a toner production method and toner that can achieve both high-temperature offset resistance and low-temperature fixability by considering the influence on resin physical properties caused by crosslinking, and high hydrolysis resistance. A developer, a developing device, and an image forming apparatus are provided.

The present invention is a method for producing a toner comprising at least a binder resin, a colorant and a carbodiimide compound,
The binder resin includes at least a polyester resin, and the acid value of the binder resin is 5 mgKOH / g or more and 30 mgKOH / g or less,
The carbodiimide compound is a compound having two or more carbodiimide groups in the molecule, and the carbodiimide group contained in the carbodiimide compound reacts with the terminal carboxyl group contained in the binder resin to crosslink the binder resin.
Equivalent %, which is the ratio of the equivalent amount of carbodiimide groups, which is the number of moles of carbodiimide groups to 100 g of binder resin, with respect to the equivalent of carboxyl groups, which is the number of moles of carboxyl groups, relative to 100 g of binder resin , satisfies the following formula (1). A method for producing a toner.
−0.78x + 23.9 ≦ y ≦ −2.8x + 94 (1)
(In the formula, x represents the acid value of the binder resin, and y represents the equivalent percentage.)

The present invention also includes a pre-mixing step of obtaining a mixture by mixing at least a binder resin , a colorant, and the carbodiimide compound ;
A melt-kneading step of melt-kneading the mixture to obtain a melt-kneaded product;
A pulverizing step of pulverizing the melt-kneaded product to obtain a pulverized product;
And a classification step of classifying the pulverized product.

  Further, the present invention is characterized in that the binder resin is crosslinked using a carbodiimide compound in the melt-kneading step.

  The present invention also provides a toner manufactured by the toner manufacturing method.

Or the invention, the binder resin is characterized in that it comprises at least biomass resin.

The present invention also provides a developer comprising the toner.
Further, the present invention is a two-component developer comprising the toner and a carrier.

  According to another aspect of the present invention, there is provided a developing device that forms a toner image by developing a latent image formed on an image forming body using the developer.

The present invention also provides an image forming apparatus comprising the developing device.
The present invention also includes a toner image forming unit that includes an image forming body and the developing device, and forms a toner image on the surface of the image forming body.
Transfer means for transferring a toner image to a recording medium;
The recording medium on which the toner image is transferred is passed through a press-contact portion formed by a fixing roller and a pressurizing unit that presses the outer peripheral surface of the fixing roller, so that the toner contained in the toner image is melted by heat. And a fixing means for fixing the toner image.

According to the present invention, in the toner production method including at least the binder resin, the colorant, and the carbodiimide compound, the acid value of the binder resin is 5 mgKOH / g or more and 30 mgKOH / g or less, and the carbodiimide group contained in the carbodiimide compound is The number of moles of carbodiimide groups relative to 100 g of binder resin relative to the equivalent of carboxyl groups, which is the number of moles of carboxyl groups relative to 100 g of binder resin, by reacting with terminal carboxyl groups contained in the binder resin. The equivalent% which is the ratio of the equivalent of the carbodiimide group which satisfy | fills Formula (1). When the carbodiimide group contained in the carbodiimide compound reacts with the terminal carboxyl group contained in the binder resin, the hydrolysis resistance of the binder resin can be improved. Further, by crosslinking the resin contained in the binder resin, the melt viscosity of the binder resin can be increased and the high temperature offset resistance can be improved as compared with the case where the resin is not crosslinked. Since the equivalent% satisfies the formula (1), the amount of the carbodiimide compound added is regulated according to the acid value of the binder resin, and thereby the degree of crosslinking between the binder resins can be controlled. The high temperature offset resistance can be improved without impairing the low temperature fixability of the toner. Therefore, it is possible to obtain a toner having both high-temperature offset resistance and low-temperature fixability and also having high hydrolysis resistance due to end-capping of carboxyl groups.
A carbodiimide compound having two or more carbodiimide groups in the molecule is used. Thereby, the carboxyl group contained in the binder resin can be blocked to further improve the hydrolysis resistance, and the binder resin can be cross-linked to further improve the high temperature offset resistance.
Further, the binder resin includes at least a polyester resin. As a result, both sharp melt characteristics and durability can be provided, and the low-temperature fixability can be improved. In addition, since the polyester resin is excellent in transparency, when the binder resin contains the polyester resin, the color is excellent in color developability, and the color of the secondary color produced by overlaying with other color toners is excellent. Can be toner.

  According to the invention, the toner production method is a melt-kneading and pulverizing method including a premixing step, a melt-kneading step, a pulverizing step, and a classification step. As a result, the toner can be manufactured with the simplest equipment among various toner manufacturing methods, and the toner can be advantageously manufactured in terms of cost.

  According to the invention, the binder resin is crosslinked using a carbodiimide compound in the melt-kneading step. In the melt-kneading step, crosslinking is performed in advance by simultaneously crosslinking the binder resin by reacting the terminal carboxyl group contained in the binder resin with the carbodiimide compound and melt-kneading the mixture obtained in the pre-mixing step. Compared to the case where the binder resin and the high molecular weight binder resin are melt-kneaded, it is possible to prevent the crosslinking component and the high molecular weight component in the binder resin from being cut by the shearing force of the melt-kneading. Therefore, there is no variation in the lot of the kneaded product due to the kneading conditions, and a uniform melt-kneaded product can be produced.

  According to the invention, the toner is produced by the toner production method of the invention. Since the terminal carboxyl group contained in the binder resin is blocked with a carbodiimide compound and the addition amount of the carbodiimide compound is adjusted according to the acid value of the binder resin, the toner production method of the present invention is produced by the above production method. Thus, a toner having both high-temperature offset resistance and low-temperature fixability and further high hydrolysis resistance can be realized. By forming an image using such a toner, it is possible to stably form a good image without fixing defects over a long period of time regardless of humidity.

  Moreover, according to this invention, binder resin contains biomass resin. This makes it possible to obtain a carbon neutral toner in consideration of global environmental conservation.

  According to the invention, the developer contains the toner of the invention. As a result, a developer having both high-temperature offset resistance and low-temperature fixability and high hydrolysis resistance can be obtained.

  According to the invention, the developer is a two-component developer comprising the toner of the invention and a carrier. Since the toner of the present invention can maintain storage stability while ensuring low-temperature fixability of the toner, a two-component developer that maintains stable performance against stress such as stirring in the developing tank is provided. can get. By using such a two-component developer, the adhesiveness to a medium such as paper is high, and a good image can be stably formed.

  Further, according to the present invention, since the latent image is developed using the developer of the present invention, a good toner image can be stably formed on the image forming body. Therefore, a good image can be stably formed.

  Further, according to the present invention, an image forming apparatus is realized by including the developing device of the present invention capable of forming a good toner image as described above. By forming an image with such an image forming apparatus, a good image can be stably formed over a long period of time.

  According to the invention, an image forming body on which a latent image is formed, a toner image forming means for forming a toner image on the surface of the image forming body, a transfer means for transferring the toner image to a recording medium, a fixing roller, The recording medium on which the toner image is transferred is passed through a pressure contact portion formed by a pressing unit that presses the outer peripheral surface of the fixing roller, so that the toner contained in the toner image is thermally melted, and the toner image is recorded on the recording medium. By forming an image with an image forming apparatus provided with a fixing means for fixing to the toner, it is possible to effectively draw out the physical properties of the toner that achieves both low-temperature fixability and heat-resistant stability, and a good image can be obtained over a long period of time. It can be formed stably.

1. Toner Manufacturing Method The first embodiment of the present invention is a toner manufacturing method containing at least a binder resin, a colorant, and a carbodiimide compound. In the toner production method, the acid value of the binder resin is 5 mgKOH / g or more and 30 mgKOH / g or less, and the carbodiimide group contained in the carbodiimide compound reacts with the terminal carboxyl group contained in the binder resin to form a bond. The equivalent% which is the ratio of the equivalent of the carbodiimide group which is the number of moles of the carbodiimide group with respect to 100 g of the binder resin to the equivalent of the carboxyl group which is the mole number of carboxyl group with respect to 100 g of the binder resin is crosslinked by the following formula: Satisfy (1).
−0.78x + 23.9 ≦ y ≦ −2.8x + 94 (1)
(In the formula, x represents the acid value of the binder resin, and y represents the equivalent percentage.)

  When the carbodiimide group contained in the carbodiimide compound reacts with the terminal carboxyl group contained in the binder resin, the hydrolysis resistance of the binder resin can be improved. Further, by crosslinking the resin contained in the binder resin, the melt viscosity of the binder resin can be increased and the high temperature offset resistance can be improved as compared with the case where the resin is not crosslinked. Since the equivalent% satisfies the formula (1), the amount of the carbodiimide compound added is regulated according to the acid value of the binder resin, and thereby the degree of crosslinking between the binder resins can be controlled. The high temperature offset resistance can be improved without impairing the low temperature fixability of the toner. Therefore, it is possible to obtain a toner having both high-temperature offset resistance and low-temperature fixability and also having high hydrolysis resistance due to end-capping of carboxyl groups.

  In the present embodiment, the crosslinking means that one or more carboxyl groups contained in the binder resin react with one or more carbodiimide groups contained in the carbodiimide compound, or a carboxyl group contained in the binder resin, By reacting with the carbodiimide group contained in the carbodiimide compound, it means that the polymer chains of a plurality of binder resins are crosslinked.

  FIG. 1 is a flowchart illustrating an example of a procedure in the toner manufacturing method of the present embodiment. As shown in FIG. 1, the toner manufacturing method of the present embodiment includes a pre-mixing step (step S1) in which toner raw materials such as a binder resin, a colorant, a release agent, and a charge control agent are mixed to produce a mixture. ), A melt-kneading step (step S2) in which the mixture is melt-kneaded to prepare a melt-kneaded product, a pulverizing step (step S3) in which the melt-kneaded product is pulverized to prepare a pulverized product, And a classification step (step S4) for removing coarse powder. Since the toner production method of the present embodiment is a melt-kneading pulverization method including these steps, the toner can be produced with the simplest equipment among various toner production methods, which is advantageous in terms of cost. Toner can be produced.

Below, each manufacturing process of step S1-step S4 is demonstrated in detail.
(1) Premixing step In the premixing step of step S1, at least a binder resin and a colorant are mixed. The toner manufactured by the toner manufacturing method of the present embodiment includes a binder resin, a carbodiimide compound, and a colorant as essential components, and further includes a toner additive such as a release agent and a charge control agent. May be. In the pre-mixing step S1, a binder is used to dry-mix the binder resin and the colorant, and other toner additive components such as a release agent and a charge control agent used as necessary.

  A known mixer can be used for dry mixing. For example, a Henschel mixer (trade name: FM mixer, manufactured by Mitsui Mining Co., Ltd.), a super mixer (trade name, manufactured by Kawata Co., Ltd.), a mechano mill (product) Name, Okada Seiko Co., Ltd. and other Henschel type mixing devices, Ongmill (trade name, manufactured by Hosokawa Micron Co., Ltd.), hybridization system (trade name, manufactured by Nara Machinery Co., Ltd.), Cosmo System (trade name, Kawasaki Heavy Industries, Ltd.) Etc.).

  In the present embodiment, a resin having an acid value of 5 mgKOH / g or more and 30 mgKOH / g or less is used as the binder resin. By using a binder resin having an acid value within such a range, a toner having excellent fixability and excellent charging stability can be obtained. When the acid value is less than 5 mgKOH / g, the affinity between a functional group such as a carboxyl group due to the acid value and a medium such as paper is reduced, and the fixing strength is lowered, so that the fixing property is lowered. When the acid value exceeds 30 mgKOH / g, the hygroscopicity increases due to the functional group resulting from the acid value, and the charge amount changes depending on the use environment. Specifically, the charge amount decreases in a high temperature and high humidity environment. The acid value of the binder resin is measured according to a potentiometric titration method or a neutralization titration method described in Japanese Industrial Standard (JIS) K0070-1992.

<Toner raw material>
(Binder resin)
The binder resin is not particularly limited as long as the acid value is in the above range, and a general thermoplastic resin can be used, for example, a polyester resin, an acrylic resin, a polyurethane resin, and an epoxy resin. Is mentioned. These resins may be used in combination of two or more resins having one or more different physical properties such as molecular weight and monomer composition in the same type of resin. In the present embodiment, the ratio of various resins in the binder resin is not particularly limited.

  The polyester resin is not particularly limited, and known resins can be used. Examples thereof include polycondensation products of polybasic acids and polyhydric alcohols. Polybasic acids are polybasic acids and derivatives of polybasic acids such as acid anhydrides or esterified products of polybasic acids. Polyhydric alcohols are compounds containing two or more hydroxyl groups, and include both alcohols and phenols.

  As polybasic acids, those commonly used as monomers of polyester resins can be used, for example, aromatic carboxylic acids such as terephthalic acid, isophthalic acid, phthalic anhydride, trimellitic anhydride, pyromellitic acid and naphthalenedicarboxylic acid, Mention may be made of aliphatic carboxylic acids such as maleic anhydride, fumaric acid, succinic acid and adipic acid. Polybasic acids may be used alone or in combination of two or more.

  Polyhydric alcohols that are commonly used as monomers of polyester resins can be used, for example, aliphatic polyhydric alcohols such as ethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol and glycerin, cyclohexanediol, Examples include alicyclic polyhydric alcohols such as cyclohexanedimethanol and hydrogenated bisphenol A, and aromatic diols such as bisphenol A ethylene oxide adduct and bisphenol A propylene oxide adduct. “Bisphenol A” is 2,2-bis (p-hydroxyphenyl) propane. Examples of the ethylene oxide adduct of bisphenol A include polyoxyethylene-2,2-bis (4-hydroxyphenyl) propane. Examples of the propylene oxide adduct of bisphenol A include polyoxypropylene-2,2-bis (4-hydroxyphenyl) propane. Polyhydric alcohols may be used alone or in combination of two or more.

  The polyester resin can be synthesized by a condensation polymerization reaction. For example, it can be synthesized by polycondensation reaction, specifically dehydration condensation reaction of polybasic acids and polyhydric alcohols in the presence of a catalyst in an organic solvent or without solvent. At this time, a demethanol polycondensation reaction may be carried out using a methyl esterified product of a polybasic acid as part of the polybasic acid. The polycondensation reaction between the polybasic acid and the polyhydric alcohol may be terminated when the acid value and softening temperature of the polyester resin to be produced reach the values in the polyester resin to be synthesized. In this polycondensation reaction, by appropriately changing the reaction conditions such as the blending ratio of polybasic acids and polyhydric alcohols and the reaction rate, for example, the content of carboxyl groups bonded to the terminal of the resulting polyester resin, and thus By adjusting the acid value of the obtained polyester resin, other physical property values such as the softening temperature can be adjusted.

  The acrylic resin is not particularly limited, and known ones can be used. Examples thereof include a homopolymer of an acrylic monomer and a copolymer of an acrylic monomer and a vinyl monomer. Among these, an acrylic resin having an acidic group is preferable. As the acrylic monomer, those commonly used as acrylic resin monomers can be used. For example, acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, acrylic Acrylate monomers such as n-amyl acid, isoamyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, decyl acrylate and dodecyl acrylate, and methyl methacrylate, methacrylic acid Propyl acid, n-butyl methacrylate, isobutyl methacrylate, n-amyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, decyl methacrylate and dodecyl methacrylate Like methacrylic acid ester monomers such as. These acrylic monomers may have a substituent. Examples of the acrylic monomer having a substituent include an acrylic ester monomer or a methacrylate ester monomer having a hydroxyl group such as hydroxyethyl acrylate and hydroxypropyl methacrylate. One acrylic monomer may be used alone, or two or more acrylic monomers may be used in combination. Known vinyl monomers can be used, for example, aromatic vinyl monomers such as styrene and α-methylstyrene, aliphatic vinyl monomers such as vinyl bromide, vinyl chloride and vinyl acetate, acrylonitrile and methacrylate. Examples include acrylonitrile monomers such as nitrile. A vinyl monomer may be used individually by 1 type, and may be used in combination of 2 or more type.

  The acrylic resin may be, for example, one or more of acrylic monomers, or one or more of acrylic monomers and one or more of vinyl monomers in the presence of a radical polymerization initiator. Further, it can be produced by polymerizing by a solution polymerization method, a suspension polymerization method or an emulsion polymerization aggregation method. An acrylic resin having an acidic group is, for example, an acrylic monomer or an acrylic monomer containing an acidic group or a hydrophilic group and a vinyl type having an acidic group or a hydrophilic group when an acrylic monomer or an acrylic monomer and a vinyl monomer are polymerized. It can be produced by using either one or both of the monomers.

  It does not restrict | limit especially as a polyurethane resin, A well-known thing can be used, For example, the addition polymerization product of a polyol and polyisocyanate is mentioned. Among these, a polyurethane resin having an acidic group or a basic group is preferable. The polyurethane resin having an acidic group or a basic group can be synthesized, for example, by subjecting a polyol having an acidic group or a basic group to a polyisocyanate by an addition polymerization reaction. Examples of the polyol having an acidic group or basic group include diols such as dimethylolpropionic acid and N-methyldiethanolamine, polyether polyols such as polyethylene glycol, polyester polyols, acrylic polyols, and polybutadiene polyols. Examples include polyols. A polyol can be used individually by 1 type or can use 2 or more types together. Examples of the polyisocyanate include tolylene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate. A polyisocyanate may be used individually by 1 type, and may be used in combination of 2 or more type.

  The epoxy resin is not particularly limited, and a known one can be used. For example, bisphenol A type epoxy resin synthesized from bisphenol A and epichlorohydrin, synthesized from phenol novolak and epichlorohydrin which are reaction products of phenol and formaldehyde. Phenol novolac type epoxy resin, and cresol novolak type epoxy resin synthesized from cresol novolak and epichlorohydrin which are reaction products of cresol and formaldehyde. Among these, an epoxy resin having an acidic group or a basic group is preferable. The epoxy resin having an acidic group or a basic group is based on, for example, the above-mentioned epoxy resin, and a polycarboxylic acid such as adipic acid or trimellitic anhydride or an amine such as dibutylamine or ethylenediamine is added to the base epoxy resin. It can be produced by addition or addition polymerization.

Among these binder resins, it is preferable to use a polyester resin. Since the polyester resin has a lower softening temperature (T _1/2 ) than other resins such as an acrylic resin, a toner having excellent low-temperature fixability that can be fixed at a lower temperature can be obtained by using the polyester resin. Can do. In addition, since the polyester resin is excellent in transparency, by using the polyester resin, it is possible to obtain a color toner having excellent color developability and excellent secondary color developability produced by superimposing with other color toners. it can.

(Biomass resin)
In the present embodiment, the binder resin preferably contains a biomass resin. By including the biomass resin in the binder resin, it is possible to obtain a carbon neutral toner in consideration of global environment conservation.

  In the present embodiment, the biomass resin is a resin that contains, as a raw material, a compound having a skeleton of carbon atoms taken by a plant by photosynthesis from carbon dioxide in the atmosphere. For this reason, even if biomass resin is burned to generate carbon dioxide, the amount of carbon dioxide in the atmosphere does not substantially increase, and the total amount of carbon dioxide in the atmosphere does not change. Therefore, it can be said that the toner containing biomass resin is a toner that can suppress environmental pollution.

  However, such biomass resin is highly hydrolyzable. Therefore, there is a problem that the toner containing biomass resin has poor stability over time and it is difficult to maintain the initial performance. However, when the toner containing biomass resin is manufactured by the toner manufacturing method of this embodiment, carbodiimide is used. Since the compound reacts with the terminal carboxyl group contained in the biomass resin, the hydrolysis resistance of the biomass resin can be improved, and the initial performance can be maintained.

  Biomass resins are broadly classified into natural product resins that can be used as polymers, chemically synthesized resins that chemically polymerize biomass-derived polymers or monomers, and microbial-produced resins that are polymerized in the body of microorganisms. Is done.

  Examples of the natural product resin include cellulose acetate, esterified starch, chitosan, fibroin, collagen, gelatin, and natural rubber.

  Examples of the chemically synthesized resin include polylactic acid, polyglycol, polymethylene terephthalate, and polybutylene succinate.

  Examples of the microorganism-producing resin include polyhydroxybutyrate, polyhydroxyalkanoate, bacterial cellulose, and polyglutamic acid.

  The biomass resin is not particularly limited. For example, polylactic acid, polymethylene terephthalate, polybutylene succinate, polyhydroxybutyrate, polyhydroxyalkanoate, succinic acid, itaconic acid, 1,3-propanediol, 1,4- A polyester resin synthesized using butanediol or the like as a monomer can be used, and one kind may be used alone, or two or more kinds may be used in combination.

  The physical properties of the binder resin other than the acid value will be described below. The binder resin may be used alone or in combination of two or more. The physical properties of various resins can be selected so that the physical properties of the resin are the following physical properties.

  The glass transition temperature (Tg) of the binder resin is not particularly limited and can be appropriately selected from a wide range, but it is preferably 40 ° C. or higher and 80 ° C. or lower in consideration of the fixing property and storage stability of the obtained toner. . When the temperature is less than 30 ° C., the storage stability becomes insufficient, so that the toner is likely to be thermally aggregated inside the image forming apparatus, and development failure may occur. Further, the temperature at which the high temperature offset phenomenon starts to occur (hereinafter referred to as “high temperature offset start temperature”) is lowered. “High temperature offset phenomenon” means that when toner is fixed on a recording medium by heating and pressurizing with a fixing member such as a heating roller, the cohesive force of toner particles adheres between the toner and the fixing member due to overheating of the toner. This is a phenomenon in which the toner layer is divided below the force and a part of the toner adheres to the fixing member and is removed. On the other hand, when the temperature exceeds 80 ° C., the fixing property is deteriorated, so that fixing failure may occur.

The softening temperature (T _1/2 ) of the binder resin is not particularly limited and can be appropriately selected from a wide range, but is preferably 150 ° C. or lower, and more preferably 60 ° C. or higher and 120 ° C. or lower. When the temperature is lower than 60 ° C., the storage stability of the toner is lowered, and the toner is likely to be thermally aggregated inside the image forming apparatus, so that the toner cannot be stably supplied to the image forming body and development failure occurs. There is a risk. In addition, a failure of the image production apparatus may be induced. If the temperature exceeds 120 ° C., the binder resin is difficult to melt in the kneading step, so that it becomes difficult to knead the toner raw material, and the dispersibility of the colorant, release agent, charge control agent, etc. in the kneaded product may be reduced. There is. Further, when the toner is fixed on the recording medium, the toner is hardly melted or softened, so that the fixing property of the toner to the recording medium is lowered, and there is a possibility that a fixing defect occurs.

The molecular weight of the binder resin is not particularly limited and can be appropriately selected from a wide range, but it is preferably 5000 to 500,000 in terms of weight average molecular weight (Mw). If it is less than 5000, the mechanical strength of the binder resin is lowered, and the resulting toner particles are easily pulverized by stirring inside the developing device, and the shape of the toner particles changes, for example, the charging performance varies. There is a fear. On the other hand, if it exceeds 500,000, it becomes difficult to melt, so that kneading in the kneading step becomes difficult, and the dispersibility of the colorant, release agent, charge control agent and the like in the kneaded product may be lowered. In addition, the fixing property of the toner is lowered, and there is a possibility that fixing failure occurs. Here, the weight average molecular weight of the binder resin is determined by gel permeation chromatography (Gel
Permeation chromatography (abbreviation: GPC) is a value in terms of polystyrene measured by GPC).

(Carbodiimide compound)
The carbodiimide compound is not particularly limited as long as it has a carbodiimide group in the molecule and forms a carbamoylamide bond by reaction with the carboxyl group of the binder resin, but there are two or more in the molecule. It is preferable to use a compound having a carbodiimide group. By using a carbodiimide compound, the carboxyl group contained in the binder resin can be blocked to improve hydrolysis resistance, and the binder resin can be cross-linked to improve high temperature offset resistance. When a compound having two or more carbodiimide groups in the molecule is used, hydrolysis resistance and high temperature offset resistance can be further improved.

  Examples of the compound having two or more carbodiimide groups in the molecule include polycarbodiimide resins. This is because the raw material isocyanate compound is heated at 120 to 150 ° C. in the presence of a carbodiimidization catalyst such as 3-methyl-1-phenyl-2-phospholene oxide and 1-phenyl-2-phospholene-1-oxide. It can be obtained by a decarboxylation condensation reaction carried out under pressure at the reaction temperature or in a solvent such as aliphatic acetate, halogen or alicyclic ether.

  As raw material isocyanate compounds for producing polycarbodiimide resins, n-butyl isocyanate, tert-butyl diisocyanate, iso-butyl isocyanate, ethyl isocyanate, n-propyl isocyanate, iso-propyl isocyanate, cyclohexyl isocyanate, n-octadecyl isocyanate 2,4-toluylene diisocyanate, 2,6-toluylene diisocyanate, o-tolidine diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 4,4'-diphenyl ether diisocyanate, 3,3 '-Dimethoxy-4,4'-biphenyl diisocyanate, p-phenylene diisocyanate, naphthylene-1,5-di Isocyanate, m- xylylene diisocyanate, hydrogenated xylylene diisocyanate, m- tetramethylxylylene diisocyanate, p- tetramethylxylylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and the like isophorone diisocyanate.

  Polycarbodiimide resins obtained from the above raw materials include poly tert-butyl carbodiimide, polytetramethylxylylene carbodiimide, poly 2,4-toluylene carbodiimide, poly 2,6-toluylene carbodiimide, poly o-tolidine carbodiimide, poly 4,4'-diphenylmethane carbodiimide, poly 4,4'-dicyclohexyl methane carbodiimide, poly 4,4'-diphenyl ether carbodiimide, poly 3,3'-dimethoxy-4,4'-biphenyl carbodiimide, poly p-phenylene carbodiimide, polynaphthylene -1,5-carbodiimide, poly m-xylylene carbodiimide, polyhydrogenated xylylene carbodiimide, polyhexamethylene carbodiimide, polytrimethylhexamethylene carbodiimi , Poly isophorone carbodiimide.

  As described above, the carbodiimide compound is added according to the acid value of the binder resin. Since the carbodiimide compound is added according to the acid value of the binder resin, the formula (1) is used. The formula (1) is obtained as follows.

  A plurality of toners in which the equivalent value is kept constant and the acid value of the binder resin is changed are prepared, and the fixing property and hydrolysis resistance are evaluated. In addition, a plurality of toners in which the acid value of the binder resin is fixed and the equivalent percentage is changed are prepared, and the fixing property, hydrolysis resistance, storage stability, charging stability and light transmittance are evaluated. The evaluation methods and evaluation criteria for fixing property, hydrolysis resistance, storage stability, charging stability and light transmittance will be described in Examples described later. Equivalent% is the ratio of the equivalent of the carbodiimide group with respect to the equivalent of the carboxyl group of binder resin, and is calculated | required by following formula (2).

  Expression (2) can be rewritten as the following expression (3).

For toners with good or acceptable evaluation results of fixability, hydrolysis resistance, storage stability, charging stability and light transmission, the x-axis is the acid value of the binder resin and the y-axis is plotted as equivalent%. . An approximate straight line (A) is calculated by the least square method using the value of each acid value of the binder resin and the maximum value of the equivalent percentage with respect to each acid value. Further, the approximate straight line (B) is calculated by the least square method using the value of each acid value of the binder resin and the minimum value of the equivalent percentage with respect to each acid value. The approximate straight line (A) is represented by the following mathematical formula (A), and the approximate straight line (B) is represented by the following mathematical formula (B).
y = -2.8x + 94 (A)
y = −0.78x + 23.9 (B)

  In the range where the value of the x-axis is 5 or more and 30 or less and is surrounded by the approximate straight line (A) and the approximate straight line (B), the fixing property, hydrolysis resistance, storage stability, charging stability, and light transmittance are improved. It can be seen that the evaluation result is good or acceptable, and the acid value and equivalent percentage of the binder resin should be in this range.

From the above, the following formula (1) is finally obtained.
−0.78x + 23.9 ≦ y ≦ −2.8x + 94 (1)
(In the formula, x represents the acid value of the binder resin, and y represents the equivalent percentage.)

(Coloring agent)
Examples of the colorant include dyes and pigments. Among these, it is preferable to use a pigment. Since pigments are superior in light resistance and color developability compared to dyes, toners excellent in light resistance and color developability can be obtained by using pigments. Specific examples of the colorant include, for example, a yellow toner colorant, a magenta toner colorant, a cyan toner colorant, and a black toner colorant, as described below. Hereinafter, the color index is abbreviated as “CI”.

  Examples of the colorant for yellow toner include C.I. I. Pigment yellow 1, C.I. I. Pigment yellow 5, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 15 and C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 180, C.I. I. Organic pigments such as CI Pigment Yellow 185, inorganic pigments such as yellow iron oxide and ocher, C.I. I. Nitro dyes such as Acid Yellow 1, C.I. I. Solvent Yellow 2, C.I. I. Solvent Yellow 6, C.I. I. Solvent Yellow 14, C.I. I. Solvent Yellow 15, C.I. I. Solvent Yellow 19, and C.I. I. Examples thereof include oil-soluble dyes such as Solvent Yellow 21.

  Examples of the colorant for magenta toner include C.I. I. Pigment red 49, C.I. I. Pigment red 57, C.I. I. Pigment red 81, C.I. I. Pigment red 122, C.I. I. Solvent Red 19, C.I. I. Solvent Red 49, C.I. I. Solvent Red 52, C.I. I. Basic Red 10 and C.I. I. Disperse Red 15 etc. are mentioned.

  Examples of the colorant for cyan toner include C.I. I. Pigment blue 15, C.I. I. Pigment blue 16, C.I. I. Solvent Blue 55, C.I. I. Solvent Blue 70, C.I. I. Direct Blue 25, and C.I. I. Direct Blue 86 and the like can be mentioned.

  Examples of the colorant for black toner include carbon black such as channel black, roller black, disk black, gas furnace black, oil furnace black, thermal black, and acetylene black. From these various types of carbon black, an appropriate carbon black may be appropriately selected according to the design characteristics of the toner to be obtained.

  In addition to these pigments, red pigments and green pigments can be used. A coloring agent can be used individually by 1 type, or can use 2 or more types together. Two or more of the same color can be used, and one or more of the different colors can also be used.

  The colorant is preferably used as a masterbatch. A master batch of a colorant can be produced, for example, by kneading a synthetic resin melt and a colorant. As the synthetic resin, the same kind of resin as the toner binder resin or a resin having good compatibility with the toner binder resin is used. The use ratio of the synthetic resin and the colorant is not particularly limited, but is preferably 30 parts by weight or more and 100 parts by weight or less with respect to 100 parts by weight of the synthetic resin. The master batch is used after being granulated to a particle size of, for example, about 2 to 3 mm.

  The colorant content in the toner of the present invention is not particularly limited, but is preferably 4 parts by weight or more and 20 parts by weight or less with respect to 100 parts by weight of the binder resin. When the blending amount of the colorant is within the above range, it is possible to obtain a toner that suppresses the filler effect due to the addition of the colorant and has high coloring power. If the blending amount of the colorant exceeds 20% by weight, the fixability of the toner may be lowered due to the filler effect of the colorant.

  These colorants may be used alone or in combination of two or more different colors. Also, a plurality of colorants of the same color can be used in combination. When using a masterbatch, it is preferable to adjust the usage amount of the masterbatch so that the content of the colorant in the toner of the present invention falls within the above range. By using the colorant in the above-mentioned range, it is possible to form a good image having a sufficient image density, high color developability and excellent image quality.

(Release agent and charge control agent)
In addition to the binder resin and the colorant, the toner of the present invention may contain other toner additive components such as a release agent and a charge control agent.

  The release agent is added to impart releasability to the toner when fixing the toner to the recording medium. Therefore, compared with the case where a mold release agent is not used, the high temperature offset start temperature can be increased and the high temperature offset resistance can be improved. Further, the releasing agent is melted by heating at the time of fixing the toner, the fixing start temperature is lowered, and the high temperature offset resistance can be improved.

  As the release agent, those commonly used in this field can be used, and examples thereof include wax. As the wax, paraffin wax. Examples include natural waxes such as carnauba wax and rice wax, synthetic waxes such as polypropylene wax, polyethylene wax and Fischer-Tropsch wax, petroleum waxes such as coal waxes such as montan wax, alcohol waxes, and ester waxes. .

  A mold release agent may be used individually by 1 type, and may be used in combination of 2 or more type. The compounding amount of the release agent is not particularly limited, and is appropriately selected from a wide range according to various conditions such as the type and content of other components such as a binder resin and a colorant and the characteristics required for the toner to be produced. Although it can be selected, it is preferably 3 parts by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the binder resin. If the compounding amount of the release agent is less than 3 parts by weight, the effect of improving the low-temperature fixability and hot offset resistance may not be sufficiently exhibited. When the blending amount of the release agent exceeds 10 parts by weight, the dispersibility of the release agent in the kneaded product is lowered, and there is a possibility that a toner having a certain performance cannot be obtained stably. Further, there is a possibility that a phenomenon called filming in which toner is fused in the form of a film (film) on the surface of an image forming body such as a photoreceptor is likely to occur.

The melting point (Tm) of the release agent is preferably 50 ° C. or higher and 150 ° C. or lower, and more preferably 80 ° C. or lower. If the melting point is less than 50 ° C., the release agent may melt in the developing device and the toner particles may be aggregated or may cause defects such as filming on the surface of the photoreceptor. If it exceeds 1, the release agent cannot be sufficiently eluted when the toner is fixed on the recording medium, and the effect of improving the high temperature offset resistance may not be sufficiently exhibited. Here, the melting point of the release agent is the differential scanning calorimetry.
It is the temperature of the endothermic peak corresponding to melting of the DSC curve obtained by (Differential Scanning Calorimetry: abbreviated DSC).

  The charge control agent is added in order to impart preferable chargeability to the toner. As the charge control agent, a charge control agent for positive charge control or negative charge control can be used. For example, positive dyes such as nigrosine dyes, basic dyes, quaternary ammonium salts, quaternary phosphonium salts, aminopyrines, pyrimidine compounds, polynuclear polyamino compounds, aminosilanes, nigrosine dyes and derivatives thereof, triphenylmethane derivatives, guanidine salts, and amidine salts. Charge control agents for charge control and, for example, oil-soluble dyes such as oil black and spiron black, metal-containing azo compounds, azo complex dyes, metal salts of naphthenic acid, metal complexes and metal salts of salicylic acid and its derivatives (metal is Chromium, zinc, zirconium, etc.), boron compounds, fatty acid soaps, long-chain alkyl carboxylates, and charge control agents for controlling negative charges such as resin acid soaps. One charge control agent can be used alone, or two or more charge control agents can be used in combination. The amount of the compatible charge control agent used is preferably 0.5 to 5 parts by weight with respect to 100 parts by weight of the binder resin, more preferably 0.5 to 100 parts by weight of the binder resin. It is not less than 3 parts by weight. If the charge control agent is contained in an amount of more than 5 parts by weight, the carrier is contaminated, toner scattering occurs, and if the content of the incompatible charge control agent is less than 0.5 parts by weight, Sufficient charging characteristics cannot be imparted.

  In color toners, it is desirable to use colorless charge control agents, and metal complexes and metal salts of salicylic acid and its derivatives are preferred.

(2) Melt-kneading step In the melt-kneading step of step S2, the mixture prepared in the pre-mixing step S1 is melt-kneaded to prepare a melt-kneaded product. The melt kneading of the mixture is performed by heating to a temperature equal to or higher than the softening temperature of the binder resin and lower than the thermal decomposition temperature of the binder resin, and the binder resin is melted or softened and the binder resin other than the binder resin is used. Disperse the toner material.

(Kneading machine)
Known kneaders can be used, for example, kneaders such as kneaders, twin-screw extruders, two-roll mills, three-roll mills, lab blast mills can be used. , TEM-100B (trade name, manufactured by Toshiba Machine Co., Ltd.), PCM-65 / 87, PCM-30 (all of which are trade names, manufactured by Ikegai Co., Ltd.), etc. Name, manufactured by Mitsui Mining Co., Ltd.) and the like. The toner raw material mixture may be melt-kneaded using a plurality of kneaders. The kneading conditions can be appropriately adjusted according to various toner raw materials to be used.

  In this embodiment, it is preferable to crosslink the binder resin using a carbodiimide compound in the melt-kneading step S2. In the melt-kneading step S2, crosslinking is performed by simultaneously performing crosslinking of the binder resin by reacting a terminal carboxyl group contained in the binder resin with a carbodiimide compound, and melt-kneading of the mixture obtained in the premixing step S1. Compared to the case where the binder resin or the high molecular weight binder resin is melt kneaded in advance, the cross-linking component or the high molecular weight component in the binder resin is prevented from being cut by the shearing force of the melt kneading. Therefore, there is no variation in the lot of the kneaded product depending on the kneading conditions, and a uniform melt-kneaded product can be produced.

(3) Pulverization step In the pulverization step of step S3, the melt-kneaded product obtained in the melt-kneading step is cooled and solidified, and then pulverized to produce a pulverized product. The cooled and solidified melt-kneaded product is first roughly pulverized into a coarsely pulverized product having a volume average particle size of about 100 μm to 5 mm, for example, by a hammer mill or a cutting mill. Thereafter, the obtained coarsely pulverized product is further finely pulverized to, for example, a pulverized product having a volume average particle diameter of 15 μm or less. For finely pulverizing coarsely pulverized products, for example, a jet type pulverizer that uses a supersonic jet stream, or a space formed between a rotor (rotor) and a stator (liner) that rotate at high speed. An impact pulverizer that introduces and pulverizes coarsely pulverized material can be used.

  The cooled and solidified melt-kneaded product may be directly pulverized by a jet pulverizer or an impact pulverizer without being coarsely pulverized by a hammer mill or a cutting mill.

(4) Classification process In the classification process of step S4, the excessively pulverized toner particles and the coarse toner particles are removed from the pulverized material produced in the pulverization process by a classifier. The excessively pulverized toner particles and coarse toner particles can be recovered and used for reuse in the production of other toners.

  For the classification, a known classifier capable of removing excessively pulverized toner particles and coarse toner particles by classification using centrifugal force or wind force can be used. For example, a jet pulverizer that performs pulverization using a supersonic jet stream or An impact pulverizer that introduces and pulverizes a coarsely pulverized product into a space formed between a rotor (rotor) and a stator (liner) that rotate at high speed can be used.

  The classification is preferably carried out by appropriately adjusting the classification conditions so that the toner particles obtained after classification have a volume average particle diameter of 3 μm or more and 15 μm or less. In particular, in order to obtain a high-quality image, it is preferable that the volume average particle size of the pulverized product is 3 μm or more and 9 μm or less. In order to further improve the image quality, the volume average particle size of the pulverized product is 5 μm or more and 8 μm or less. It is preferable that If the volume average particle size of the pulverized product is less than 3 μm, the particle size of the toner becomes too small, and there is a possibility that high charge and low fluidity may occur. When this high charging and low fluidization occur, it becomes impossible to stably supply the toner to the photoreceptor, and there is a possibility that background fogging and a decrease in image density may occur. When the volume average particle size of the pulverized product exceeds 15 μm, the toner has a large particle size, so that a high-definition image cannot be obtained. Further, as the toner particle size increases, the specific surface area decreases and the charge amount of the toner decreases. When the charge amount of the toner is small, the toner is not stably supplied to the photoconductor, and there is a possibility that in-machine contamination due to toner scattering occurs.

(External additive)
The toner particles produced as described above are responsible for functions such as powder flowability improvement, triboelectric chargeability improvement, heat resistance, long-term storage stability improvement, cleaning property improvement and photoreceptor surface wear property control. Additives may be mixed. As the external additive, those commonly used in this field can be used, and examples thereof include fine silica powder, fine titanium oxide powder and fine alumina powder. These inorganic fine powders are used for the purpose of hydrophobization, chargeability control, etc. Silicone varnish, various modified silicone varnishes, silicone oil, various modified silicone oils, silane coupling agents, silane coupling agents having functional groups, and other organic It is preferable to be treated with a treating agent such as a silicon compound, and one kind can be used alone, or two or more kinds can be used in combination. As the external additive, those having a primary particle number average particle diameter of 10 nm to 500 nm are preferably used. By using an external additive having such a particle size, the effect of improving the fluidity of the toner is more easily exhibited. The external additive is added in an amount of 5% with respect to 100 parts by weight of the toner particles in consideration of the charge amount necessary for the toner, the influence of the external additive on the abrasion of the photoreceptor, the environmental characteristics of the toner, and the like. Part or less is preferred.

2. Toner The toner according to the second embodiment of the present invention is manufactured by the above-described toner manufacturing method. In the toner manufacturing method according to the first embodiment, the terminal carboxyl group contained in the binder resin is blocked with a carbodiimide compound, and the amount of the carbodiimide compound added is adjusted according to the acid value of the binder resin. By being manufactured by this method, it is possible to realize a toner that can achieve both high-temperature offset resistance and low-temperature fixability and also has high hydrolysis resistance. By forming an image using such a toner, it is possible to stably form a good image without fixing defects over a long period of time regardless of humidity.

3. Developer The developer according to the third embodiment of the present invention includes the toner according to the second embodiment. As a result, a developer having both high-temperature offset resistance and low-temperature fixability and high hydrolysis resistance can be obtained.

  As described above, a toner in which an external additive is externally added to the toner particles as needed can be used as it is as a one-component developer, or can be mixed with a carrier and used as a two-component developer. . When used as a two-component developer, the toner of the second embodiment can maintain the storage stability while ensuring the low-temperature fixability of the toner, so that it is resistant to stress such as stirring in the developing tank. Stable performance can be maintained. By using such a two-component developer, the adhesiveness to a medium such as paper is high, and a good image can be stably formed.

(Career)
As the carrier, magnetic particles can be used. Specific examples of the particles having magnetism include metals such as iron, ferrite, and magnetite, and alloys of these metals with metals such as aluminum or lead. Among these, ferrite is preferable.

  Alternatively, a resin-coated carrier in which magnetic particles are coated with a resin, or a resin-dispersed carrier in which magnetic particles are dispersed in a resin may be used as the carrier. The resin that coats the magnetic particles is not particularly limited, and examples thereof include olefin resins, styrene resins, styrene / acrylic resins, silicone resins, ester resins, and fluorine-containing polymer resins. . Moreover, although it does not restrict | limit especially as resin used for a resin dispersion type carrier, For example, a styrene acrylic resin, a polyester resin, a fluorine resin, a phenol resin, etc. are mentioned.

The shape of the carrier is preferably a spherical shape or a flat shape.
Further, the volume average particle diameter of the carrier is not particularly limited, but is preferably 10 to 100 μm, more preferably 50 μm or less in consideration of high image quality.

  By setting the volume average particle diameter of the carrier to 50 μm or less, the contact opportunities between the toner and the carrier increase, and each small-diameter toner can be appropriately charged and controlled. Can be achieved and a high-quality image can be achieved.

Furthermore, the resistivity of the carrier is preferably 10 ⁸ Ω · cm or more, more preferably 10 ¹² Ω · cm or more. The carrier resistivity is determined by placing a carrier in a container having a cross-sectional area of 0.50 cm ² and tapping it, then applying a load of 1 kg / cm ² to the particles packed in the container and placing the load between the load and the bottom electrode. This is a value obtained by reading a current value when a voltage generating an electric field of 1000 V / cm is applied. When the resistivity is low, when a bias voltage is applied to the developing sleeve, charges are injected into the carrier, and carrier particles easily adhere to the photoreceptor. Further, breakdown of the bias voltage is likely to occur.

  The magnetization strength (maximum magnetization) of the carrier is preferably 10 to 60 emu / g, more preferably 15 to 40 emu / g. The magnetization strength depends on the magnetic flux density of the developing roller, but under the general magnetic flux density conditions of the developing roller, if it is less than 10 emu / g, the magnetic binding force does not work and causes carrier scattering. There is a fear. On the other hand, if the magnetization strength exceeds 60 emu / g, it is difficult to maintain a non-contact state with the image forming body in the non-contact development in which the carrier spikes become too high. Further, in the contact development, there is a risk that a sweep is likely to appear in the toner image.

The usage ratio of the toner and carrier in the two-component developer is not particularly limited and can be appropriately selected according to the type of toner and carrier. However, if a resin-coated carrier (density 5 to 8 g / cm ² ) is taken as an example, development The toner may be used so that the toner is contained in 2 to 30% by weight, preferably 2 to 20% by weight of the total amount of the developer. In the two-component developer, the carrier coverage with the toner is preferably 40 to 80%.

4 and Image Forming Apparatus FIG. 2 is a cross-sectional view schematically showing a configuration of an image forming apparatus 1 according to the fourth embodiment of the present invention. The image forming apparatus 1 is a multifunction machine having both a copying function, a printer function, and a facsimile function, and forms a full-color or monochrome image on a recording material according to transmitted image information. That is, the image forming apparatus 1 has three types of printing modes, ie, a copier mode (copying mode), a printer mode, and a FAX mode. Operation input from an operation unit (not shown), a personal computer, a portable terminal device, and information recording A print mode is selected by a control unit (to be described later) in response to reception of a print job from an external device using a storage medium or a memory device.

  The image forming apparatus 1 includes a toner image forming unit 2, a transfer unit 3, a fixing unit 4, a recording material supply unit 5, and a discharge unit 6. Each member constituting the toner image forming unit 2 and some members included in the transfer unit 3 are black (b), cyan (c), magenta (m), and yellow (y) colors included in the color image information. In order to correspond to the image information, four each are provided. Here, each member provided by four according to each color is distinguished by attaching an alphabet representing each color to the end of the reference symbol, and when referring collectively, only the reference symbol is used.

  The toner image forming unit 2 includes a photosensitive drum 11, a charging unit 12, an exposure unit 13, a developing unit 14, and a cleaning unit 15. The charging unit 12, the developing unit 14, and the cleaning unit 15 are arranged around the photosensitive drum 11 in this order. The charging unit 12 is disposed below the developing unit 14 and the cleaning unit 15 in the vertical direction. The charging unit 12 and the exposure unit 13 correspond to a latent image forming unit.

  The photosensitive drum 11 as an image forming body is supported by a driving unit (not shown) so as to be rotatable around an axis, and includes a conductive substrate (not shown) and a photosensitive layer formed on the surface of the conductive substrate. The conductive substrate can take various shapes, and examples thereof include a cylindrical shape, a columnar shape, and a thin film sheet shape. Among these, a cylindrical shape is preferable. The conductive substrate is formed of a conductive material. As the conductive material, those commonly used in this field can be used. For example, metals such as aluminum, copper, brass, zinc, nickel, stainless steel, chromium, molybdenum, vanadium, indium, titanium, gold, platinum, and the like. A conductive layer made of one or more of aluminum, aluminum alloy, tin oxide, gold, indium oxide and the like is formed on a film-like substrate such as two or more alloys, synthetic resin film, metal film or paper. And a resin composition containing conductive particles and / or a conductive polymer. As the film-like substrate used for the conductive film, a synthetic resin film is preferable, and a polyester film is particularly preferable. As a method for forming the conductive layer in the conductive film, vapor deposition, coating, and the like are preferable.

  The photosensitive layer is formed, for example, by laminating a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material. It is preferable to provide an undercoat layer between the conductive substrate and the charge generation layer or the charge transport layer. By providing an undercoat layer, the scratches and irregularities present on the surface of the conductive substrate are coated to smooth the surface of the photosensitive layer, to prevent deterioration of the chargeability of the photosensitive layer during repeated use. Alternatively, an advantage of improving the charging characteristics of the photosensitive layer in a low humidity environment can be obtained. Further, a laminated photoreceptor having a three-layer structure having a high durability and having a photoreceptor surface protective layer as the uppermost layer may be used.

  The charge generation layer is mainly composed of a charge generation material that generates a charge when irradiated with light, and contains a known binder resin, plasticizer, sensitizer and the like as necessary. As the charge generation material, those commonly used in this field can be used, for example, perylene pigments such as perylene imide and perylene acid anhydride, polycyclic quinone pigments such as quinacridone and anthraquinone, metal and metal-free phthalocyanines, and halogenated compounds. Phthalocyanine pigments such as metal-free phthalocyanine, squalium dye, azulenium dye, thiapyrylium dye, carbazole skeleton, styryl stilbene skeleton, triphenylamine skeleton, dibenzothiophene skeleton, oxadiazole skeleton, fluorenone skeleton, bis stilbene skeleton, distyryl oxa And azo pigments having a diazole skeleton or a distyrylcarbazole skeleton. Among these, metal-free phthalocyanine pigments, oxotitanyl phthalocyanine pigments, bisazo pigments containing a fluorene ring and / or a fluorenone ring, bisazo pigments composed of aromatic amines, trisazo pigments, etc. have high charge generation ability and high sensitivity. Suitable for obtaining a photosensitive layer. One type of charge generating material can be used alone, or two or more types can be used in combination. Although the content of the charge generation material is not particularly limited, it is preferably 5 parts by weight or more and 500 parts by weight or less, more preferably 10 parts by weight or more and 200 parts by weight or less with respect to 100 parts by weight of the binder resin in the charge generation layer. is there.

  As the binder resin for the charge generation layer, those commonly used in this field can be used. For example, melamine resin, epoxy resin, silicone resin, polyurethane, acrylic resin, vinyl chloride-vinyl acetate copolymer resin, polycarbonate, phenoxy resin , Polyvinyl butyral, polyarylate, polyamide and polyester. Binder resin can be used individually by 1 type, or can use 2 or more types together as needed.

  The charge generation layer generates charge by dissolving or dispersing appropriate amounts of charge generation materials, binder resins and, if necessary, plasticizers and sensitizers in an appropriate organic solvent capable of dissolving or dispersing these components. It can be formed by preparing a layer coating solution, applying this charge generation layer coating solution to the surface of the conductive substrate, and drying. The film thickness of the charge generation layer thus obtained is not particularly limited, but is preferably 0.05 μm or more and 5 μm or less, more preferably 0.1 μm or more and 2.5 μm or less.

  The charge transport layer laminated on the charge generation layer has a charge transport material having the ability to accept and transport the charge generated from the charge generation material and a binder resin for the charge transport layer as essential components. Contains known antioxidants, plasticizers, sensitizers, lubricants and the like. As the charge transport material, those commonly used in this field can be used, for example, poly-N-vinylcarbazole and derivatives thereof, poly-γ-carbazolylethyl glutamate and derivatives thereof, pyrene-formaldehyde condensation product and derivatives thereof, Polyvinylpyrene, polyvinylphenanthrene, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, 9- (p-diethylaminostyryl) anthracene, 1,1-bis (4-dibenzylaminophenyl) propane, styrylanthracene, styrylpyrazoline, pyrazoline Derivatives, phenylhydrazones, hydrazone derivatives, triphenylamine compounds, tetraphenyldiamine compounds, triphenylmethane compounds, stilbene compounds, 3-methyl-2-benzothiazoline -Donating substances such as azine compounds, fluorenone derivatives, dibenzothiophene derivatives, indenothiophene derivatives, phenanthrenequinone derivatives, indenopyridine derivatives, thioxanthone derivatives, benzo [c] cinnoline derivatives, phenazine oxide derivatives, tetracyano And electron accepting substances such as ethylene, tetracyanoquinodimethane, promanyl, chloranil and benzoquinone. The charge transport materials can be used alone or in combination of two or more. Although the content of the charge transport material is not particularly limited, it is preferably 10 parts by weight or more and 300 parts by weight or less, more preferably 30 parts by weight or more and 150 parts by weight or less with respect to 100 parts by weight of the binder resin in the charge transport material. .

  As the binder resin for the charge transport layer, those commonly used in this field and capable of uniformly dispersing the charge transport material can be used. For example, polycarbonate, polyarylate, polyvinyl butyral, polyamide, polyester, polyketone, epoxy resin, polyurethane , Polyvinyl ketone, polystyrene, polyacrylamide, phenol resin, phenoxy resin, polysulfone resin, and copolymer resins thereof. Among these, in consideration of film formability, wear resistance of the resulting charge transport layer, electrical characteristics, etc., polycarbonate containing bisphenol Z as a monomer component (hereinafter referred to as “bisphenol Z type polycarbonate”), bisphenol Z type polycarbonate And a mixture of polycarbonate with other polycarbonates are preferred. Binder resin can be used individually by 1 type, or can use 2 or more types together.

  The charge transport layer preferably contains an antioxidant together with the charge transport material and the binder resin for the charge transport layer. As antioxidants, those commonly used in this field can be used, such as vitamin E, hydroquinone, hindered amine, hindered phenol, paraphenylenediamine, arylalkanes and their derivatives, organic sulfur compounds, and organic phosphorus compounds. Can be mentioned. One antioxidant can be used alone, or two or more antioxidants can be used in combination. The content of the antioxidant is not particularly limited, but is 0.01% by weight or more and 10% by weight or less, preferably 0.05% by weight or more and 5% by weight or less of the total amount of components constituting the charge transport layer.

  The charge transport layer is dissolved or dispersed in a suitable organic solvent that can dissolve or disperse these components in an appropriate amount such as a charge transport material and a binder resin, and if necessary, an antioxidant, a plasticizer, and a sensitizer. The charge transport layer coating solution is prepared, and the charge transport layer coating solution is applied to the surface of the charge generation layer and dried. The film thickness of the charge transport layer thus obtained is not particularly limited, but is preferably 10 to 50 μm, more preferably 15 to 40 μm.

  Note that a photosensitive layer in which a charge generation material and a charge transport material are present can be formed in one layer. In that case, the type, content, binder resin, and other additives of the charge generation material and the charge transport material may be the same as in the case of separately forming the charge generation layer and the charge transport layer.

  In this embodiment, the photosensitive drum formed by forming the organic photosensitive layer using the charge generation material and the charge transport material as described above is used. Instead, an inorganic photosensitive layer using silicon or the like is formed. Can be used.

  The charging unit 12 faces the photosensitive drum 11 and is arranged so as to be separated from the surface of the photosensitive drum 11 along the longitudinal direction of the photosensitive drum 11 with a gap, and the surface of the photosensitive drum 11 has a predetermined polarity and Charge to potential. As the charging unit 12, for example, a charging brush type charger, a charger type charger, a saw-tooth type charger, an ion generator, or the like can be used. In the present embodiment, the charging unit 12 is provided so as to be separated from the surface of the photosensitive drum 11, but is not limited thereto. For example, a charging roller may be used as the charging unit 12, and the charging roller may be arranged so that the charging roller and the photosensitive drum are in pressure contact with each other, or a contact charging type charger such as a charging brush or a magnetic brush may be used. .

  The exposure unit 13 is arranged such that light of each color information emitted from the exposure unit 13 passes between the charging unit 12 and the developing unit 14 and is irradiated on the surface of the photosensitive drum 11. The exposure unit 13 branches the image information into light of each color information of black, cyan, magenta, and yellow in the unit, and the surface of the photosensitive drum 11 charged to a uniform potential by the charging unit 12 is light of each color information. To form an electrostatic latent image on the surface. As the exposure unit 13, for example, a laser scanning unit including a laser irradiation unit and a plurality of reflecting mirrors can be used. In addition, a unit in which an LED array, a liquid crystal shutter, and a light source are appropriately combined may be used.

  The cleaning unit 15 removes the toner remaining on the surface of the photosensitive drum 11 after transferring the toner image to the recording material, and cleans the surface of the photosensitive drum 11. For the cleaning unit 15, for example, a plate-like member such as a cleaning blade is used. In the image forming apparatus 1 of the present invention, an organic photosensitive drum is mainly used as the photosensitive drum 11, and the surface of the organic photosensitive drum is mainly composed of a resin component. Surface degradation is likely to proceed due to the chemical action of ozone. However, the deteriorated surface portion is worn by receiving a rubbing action by the cleaning unit 15 and is gradually but surely removed. Therefore, the problem of surface deterioration due to ozone or the like is practically solved, and the charging potential by the charging operation can be stably maintained over a long period of time. Although the cleaning unit 15 is provided in this embodiment, the present invention is not limited to this, and the cleaning unit 15 may not be provided.

  According to the toner image forming unit 2, the surface of the photosensitive drum 11 that is uniformly charged by the charging unit 12 is irradiated with signal light corresponding to the image information from the exposure unit 13 to form an electrostatic latent image. Toner is supplied from the developing means 14 to form a toner image, and after the toner image is transferred to the intermediate transfer belt 25, the toner remaining on the surface of the photosensitive drum 11 is removed by the cleaning unit 15. This series of toner image forming operations is repeatedly executed.

  The transfer unit 3 is disposed above the photosensitive drum 11 and includes an intermediate transfer belt 25, a driving roller 26, a driven roller 27, an intermediate transfer roller 28, a transfer belt cleaning unit 29, and a transfer roller 30.

  The intermediate transfer belt 25 is an endless belt-like member that is stretched by a driving roller 26 and a driven roller 27 to form a loop-shaped movement path, and is driven to rotate in the direction of an arrow B. When the intermediate transfer belt 25 passes through the photosensitive drum 11 while being in contact with the photosensitive drum 11, an intermediate transfer roller 28 disposed on the surface of the photosensitive drum 11 is opposed to the photosensitive drum 11 via the intermediate transfer belt 25. A transfer bias having a polarity opposite to the charging polarity of the toner is applied, and the toner image formed on the surface of the photosensitive drum 11 is transferred onto the intermediate transfer belt 25. In the case of a full-color image, each color toner image formed on each photoconductor drum 11 is sequentially transferred onto the intermediate transfer belt 25 to form a full-color toner image.

  The driving roller 26 is provided so as to be rotatable around its axis by driving means (not shown), and the intermediate transfer belt 25 is driven to rotate in the direction of arrow B by the rotational driving. The driven roller 27 is provided so as to be able to be driven and rotated by the rotational drive of the driving roller 26, and applies a certain tension to the intermediate transfer belt 25 so that the intermediate transfer belt 25 does not loosen. The intermediate transfer roller 28 is provided in pressure contact with the photosensitive drum 11 via the intermediate transfer belt 25 and capable of being driven to rotate about its axis by a driving unit (not shown). The intermediate transfer roller 28 is connected to a power source (not shown) for applying a transfer bias as described above, and has a function of transferring the toner image on the surface of the photosensitive drum 11 to the intermediate transfer belt 25.

  The transfer belt cleaning unit 29 is provided so as to face the driven roller 27 through the intermediate transfer belt 25 and to contact the outer peripheral surface of the intermediate transfer belt 25. Since the toner adhering to the intermediate transfer belt 25 due to contact with the photosensitive drum 11 causes the back surface of the recording material to be contaminated, the transfer belt cleaning unit 29 removes and collects the toner on the surface of the intermediate transfer belt 25.

  The transfer roller 30 is provided in pressure contact with the drive roller 26 via the intermediate transfer belt 25, and can be driven to rotate about an axis by a drive unit (not shown). At the pressure contact portion between the transfer roller 30 and the driving roller 26, that is, the transfer nip portion, the toner image carried and conveyed by the intermediate transfer belt 25 is transferred to the recording material fed from the recording material supply means 5 described later. The The recording material carrying the toner image is fed to the fixing unit 4.

  According to the transfer unit 3, the toner image transferred from the photosensitive drum 11 to the intermediate transfer belt 25 at the pressure contact portion between the photosensitive drum 11 and the intermediate transfer roller 28 rotates the intermediate transfer belt 25 in the arrow B direction. It is conveyed to the transfer nip portion by driving, and transferred to the recording material there.

  The fixing unit 4 is provided downstream of the transfer unit 3 in the recording material conveyance direction, and includes a fixing roller 31 and a pressure roller 32. The fixing roller 31 is rotatably provided by a driving unit (not shown), and heats and melts the toner constituting the unfixed toner image carried on the recording material to fix it on the recording material. A heating unit (not shown) is provided inside the fixing roller 31. The heating unit heats the fixing roller 31 so that the surface of the fixing roller 31 reaches a predetermined temperature (heating temperature). For example, a heater or a halogen lamp can be used as the heating means. The heating means is controlled by fixing condition control means described later. The control of the heating temperature by the fixing condition control means will be described in detail later. A temperature detection sensor is provided near the surface of the fixing roller 31 to detect the surface temperature of the fixing roller 31. The detection result by the temperature detection sensor is written in the storage unit of the control means described later.

  The pressure roller 32 is provided so as to be in pressure contact with the fixing roller 31 and is supported so as to be driven to rotate by the rotation drive of the pressure roller 32. The pressure roller 32 assists fixing of the toner image on the recording material by pressing the toner and the recording material when the toner is melted and fixed on the recording material by the fixing roller 31. A pressure contact portion between the fixing roller 31 and the pressure roller 32 is a fixing nip portion.

  According to the fixing unit 4, the recording material onto which the toner image has been transferred by the transfer unit 3 is sandwiched between the fixing roller 31 and the pressure roller 32, and the toner image is recorded under heating when passing through the fixing nip portion. By being pressed against the material, the toner image is fixed on the recording material, and an image is formed.

  The recording material supply unit 5 includes an automatic paper feed tray 35, a pickup roller 36, a transport roller 37, a registration roller 38, and a manual paper feed tray 39. The automatic paper feed tray 35 is a container-like member that is provided in the lower part of the image forming apparatus 1 in the vertical direction and stores a recording material. Recording materials include plain paper, color copy paper, overhead projector sheets, postcards, and the like. The pickup roller 36 takes out the recording material stored in the automatic paper feed tray 35 one by one and feeds it to the paper transport path S1. The conveyance rollers 37 are a pair of roller members provided so as to be in pressure contact with each other, and convey the recording material toward the registration rollers 38. The registration rollers 38 are a pair of roller members provided so as to be in pressure contact with each other, and the recording material fed from the conveyance roller 37 is used for conveying the toner image carried on the intermediate transfer belt 25 to the transfer nip portion. Synchronously, it is fed to the transfer nip. The manual paper feed tray 39 is a device that takes recording material into the image forming apparatus 1 by manual operation. The recording material taken from the manual paper feed tray 39 passes through the paper conveyance path S2 by the conveyance roller 37. Then, it is fed to the registration roller 38. According to the recording material supply means 5, the toner image carried on the intermediate transfer belt 25 is conveyed to the transfer nip portion by the recording material supplied one by one from the automatic paper feed tray 35 or the manual paper feed tray 39. In synchronism with this, the sheet is fed to the transfer nip portion.

  The discharge unit 6 includes a conveyance roller 37, a discharge roller 40, and a discharge tray 41. The conveyance roller 37 is provided on the downstream side of the fixing nip portion in the sheet conveyance direction, and conveys the recording material on which the image is fixed by the fixing unit 4 toward the discharge roller 40. The discharge roller 40 discharges the recording material on which the image is fixed to a discharge tray 41 provided on the upper surface in the vertical direction of the image forming apparatus 1. The discharge tray 41 stores the recording material on which the image is fixed.

  The image forming apparatus 1 includes a control unit (not shown). The control means is provided, for example, in the upper part of the internal space of the image forming apparatus 1 and includes a storage unit, a calculation unit, and a control unit. The storage unit of the control unit includes various setting values via an operation panel (not shown) arranged on the upper surface of the image forming apparatus 1, detection results from sensors (not shown) arranged at various locations inside the image forming apparatus 1, external devices, and the like. The image information from is input. In addition, programs for executing various means are written. Examples of the various means include a recording material determination means, an adhesion amount control means, and a fixing condition control means. As the storage unit, those commonly used in this field can be used, and examples thereof include a read only memory (ROM), a random access memory (RAM), and a hard disk drive (HDD).

  As the external device, an electric / electronic device that can form or acquire image information and can be electrically connected to the image forming apparatus can be used. For example, a computer, a digital camera, a television, a video recorder, a DVD recorder, HDDVD, Blu-ray disc recorder, facsimile machine, portable terminal device, etc.

  The calculation unit takes out various data written in the storage unit, that is, an image formation command, a detection result, image information, and a program of various means, and performs various determinations. The control unit sends a control signal to the corresponding device according to the determination result of the calculation unit, and performs operation control. The control unit and the calculation unit include a processing circuit realized by a microcomputer having a central processing unit (CPU), a microprocessor, or the like. The control means includes a main power supply together with the processing circuit described above, and the power supply supplies power not only to the control means but also to each device in the image forming apparatus.

  FIG. 3 is a schematic cross-sectional view schematically showing the configuration of the developing device 20 shown in FIG. The developing unit 14 includes a developing tank 20 and a toner hopper 21. The developing tank 20 is disposed so as to face the surface of the photosensitive drum 11, and is a container that supplies toner to the electrostatic latent image formed on the surface of the photosensitive drum 11 and develops it to form a visible toner image. It is a shaped member. The developing tank 20 accommodates toner in its internal space and accommodates a roller member such as the developing roller 110, the supply roller 111, and the stirring roller 112 or a screw member, and rotatably supports the developing tank. An opening 114 is formed on a side surface of the developing tank 20 facing the photosensitive drum 11, and the developing roller 110 is rotatably provided at a position facing the photosensitive drum 11 through the opening 114.

  The developing roller 110 is a roller-like member that supplies toner to the electrostatic latent image on the surface of the photoconductor 11 at the pressure contact portion or the closest portion with the photoconductor drum 11. When supplying the toner, a potential having a polarity opposite to the charging potential of the toner is applied to the surface of the developing roller 110 as a developing bias voltage (hereinafter simply referred to as “developing bias”). As a result, the toner on the surface of the developing roller 110 is smoothly supplied to the electrostatic latent image. Further, by changing the developing bias value, the amount of toner (toner adhesion amount) supplied to the electrostatic latent image can be controlled.

  The supply roller 111 is a roller-like member provided to face the developing roller 110 so as to be rotationally driven, and supplies toner to the periphery of the developing roller 110. The agitating roller 112 is a roller-like member provided so as to be able to rotate and face the supply roller 111, and supplies the toner newly supplied from the toner hopper 21 into the developing tank 20 to the periphery of the supply roller 111.

  The toner hopper 21 is provided so that a toner replenishing port 113 provided at the lower part in the vertical direction and a toner receiving port 115 provided at the upper part in the vertical direction of the developing tank 20 communicate with each other. Add toner. Further, the toner hopper 21 may not be used, and the toner may be directly supplied from each color toner cartridge.

  As described above, since the developing device 14 of the present invention develops the latent image using the developer of the present invention, a good toner image can be stably formed on the photosensitive drum 11. Therefore, a good image can be stably formed. Further, as described above, the image forming apparatus 1 is realized by including the developing device 14 of the present invention capable of forming a good toner image. By forming an image with such an image forming apparatus 1, a good image can be stably formed over a long period of time.

  The image forming apparatus 1 of the present invention includes a photosensitive drum 11 on which a latent image is formed, a toner image forming unit that forms a toner image on the surface of the photosensitive drum 11, a transfer unit that transfers the toner image to a recording medium, The toner contained in the toner image is thermally melted by passing the recording medium onto which the toner image is transferred through a pressure contact portion formed by a fixing roller and a pressing unit that presses the outer peripheral surface of the fixing roller, thereby An image forming apparatus 1 is realized including a fixing unit that fixes an image on a recording medium. By forming an image with such an image forming apparatus 1, it is possible to effectively draw out the physical properties of the toner that achieves both low-temperature fixability and heat resistance stability, and stably form a good image over a long period of time. can do.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.
The volume average particle diameter and coefficient of variation CV, the glass transition temperature (Tg) of the binder resin, the softening temperature (T _1/2 ) of the binder resin, the molecular weight and the molecular weight distribution index of the binder resin in Examples and Comparative Examples (Mw / Mn), the acid value of the binder resin, the THF-insoluble content of the binder resin, and the melting point (Tm) of the release agent were measured as follows.

[Volume average particle diameter of toner]
To 50 ml of electrolyte (trade name: ISOTON-II, manufactured by Beckman Coulter, Inc.), 20 mg of a sample and 1 ml of sodium alkyl ether sulfate (dispersant, manufactured by Kishida Chemical Co., Ltd.) are added, and an ultrasonic disperser (trade name: UH). -50, manufactured by STM) and subjected to ultrasonic dispersion treatment at an ultrasonic frequency of 20 kHz for 3 minutes was used as a measurement sample. About this measurement sample, the particle size distribution measuring device (trade name: Multisizer 3, manufactured by Beckman Coulter, Inc.) is used to measure the volume particle size distribution of the sample particles under the conditions of an aperture diameter of 100 μm and the number of measured particles of 50000 counts. The particle size d _{50 at} which the cumulative volume from the large particle size side in the cumulative volume distribution becomes 50% was measured.

[Glass transition temperature of binder resin (Tg)]
Using a differential scanning calorimeter (trade name: Diamond DSC, manufactured by PerkinElmer Japan Co., Ltd.), a sample 0.01 g was heated at a heating rate of 10 ° C. per minute (10 ° C./min) according to Japanese Industrial Standard (JIS) K7121-1987. ) And the DSC curve was measured. The intersection of the straight line obtained by extending the low-temperature base line of the endothermic peak corresponding to the glass transition of the obtained DSC curve to the high-temperature side and the tangent line drawn at the point where the slope is maximum with respect to the low-temperature curve of the peak. The temperature was determined as the glass transition temperature (Tg).

[Binder resin softening temperature (T _1/2 )]
Using a flow characteristic evaluation apparatus (trade name: Flow Tester CFT-500C, manufactured by Shimadzu Corporation), 1 g of a sample is inserted into a cylinder, and a load of 10 kgf / cm ² (0.980665 MPa) is applied so as to be extruded from a die. While heating at a heating rate of 6 ° C./min (6 ° C./min), the temperature at which half of the sample flowed out of the die was determined as the softening temperature. A die having a diameter of 1 mm and a length of 1 mm was used.

[Molecular weight and molecular weight distribution index of binder resin (Mw / Mn)]
Using a GPC apparatus (trade name: HLC-8220 GPC, manufactured by Tosoh Corporation), at a temperature of 40 ° C., a 0.25 wt% tetrahydrofuran (hereinafter referred to as THF) solution of the sample was used as the sample solution, and the sample solution was injected. The molecular weight distribution curve was determined with an amount of 200 μL. The molecular weight at the peak of the obtained molecular weight distribution curve was determined as the peak top molecular weight. Further, from the obtained molecular weight distribution curve, a weight average molecular weight Mw and a number average molecular weight Mn are obtained, and a molecular weight distribution index (Mw / Mn; hereinafter, simply “Mw / Mn”) is a ratio of the weight average molecular weight Mw to the number average molecular weight Mn. Also expressed). The molecular weight calibration curve was prepared using standard polystyrene.

[Acid value of binder resin]
The acid value of the binder resin was measured by the neutralization titration method described in Japanese Industrial Standard (JIS) K0070-1992. A sample of 5 g was dissolved in 50 mL of THF, and several drops of an ethanol solution of phenolphthalein was added as an indicator, followed by titration with a 0.1 mol / L potassium hydroxide (KOH) aqueous solution. The point at which the color of the sample solution changed from colorless to purple was used as the end point, and the acid value (mgKOH / g) was calculated from the amount of potassium hydroxide aqueous solution required to reach the end point and the weight of the sample subjected to titration. .

[THF insoluble matter in binder resin]
1 g of the sample was put into a cylindrical filter paper, passed through a Soxhlet extractor, heated and refluxed for 6 hours using 100 mL of THF as a solvent, and components soluble in THF in the sample were extracted with THF. After removing the solvent from the extracted extract containing the THF-soluble matter, the THF-soluble matter was dried at 100 ° C. for 24 hours, and the weight X (g) of the obtained THF-soluble matter was weighed. From the obtained THF soluble weight X (g) and the weight of the sample used for measurement (1 g), based on the following formula (4), THF insoluble component in THF in the binder resin The ratio P (% by weight) of the minutes was calculated. Hereinafter, this ratio P is referred to as THF insoluble matter.
P (% by weight) = [{1 (g) −X (g)} / 1 (g)] × 100 (4)

[Melting point of release agent (Tm)]
Using a differential scanning calorimeter (trade name: Diamond DSC, manufactured by Perkin Elmer Japan Co., Ltd.), according to Japanese Industrial Standard (JIS) K7121-1987, 0.01 g of a sample was obtained at a temperature of 20 ° C. to 200 ° C. per minute at 10 ° C. The temperature was raised at a rate of 50 ° C. per minute from 200 ° C. to 20 ° C., and then heated again at a rate of 10 ° C. per minute from 20 ° C. to 200 ° C. About the peak of the heat of fusion of the DSC curve obtained, the temperature at the top of the peak was determined as the melting point (Tm).

(Preparation of binder resin)
Polyester resin A (glass transition temperature (Tg): 60 ° C., softening temperature (T _1/2 ): 125 ° C., weight average molecular weight 72500, Mw / Mn = 15.2, acid value 3, THF insoluble content 5%) 90 0.0 part by weight and 10.0 parts by weight of polylactic acid resin (trade name: Terramac TE-2000C, manufactured by Unitika Co., Ltd., melting point (Tm): 170 ° C.) are placed in a container equipped with a stirrer and a heating device and stirred. While raising the temperature to 220 ° C., the resin was melted. Stirring is continued until the desired acid value is reached, and the binder resin B (glass transition temperature (Tg): 55 ° C., softening temperature (T _1/2 ): 110 ° C., peak top molecular weight 10500, Mw / Mn = 5.1, acid value 5 (mgKOH / g), THF-insoluble content 4%). Binder resins C, D, E, F, and G were obtained in the same manner as the production method of the binder resin B except that the stirring conditions and the heating conditions were changed. Table 1 summarizes the physical properties of the binder resins A, B, C, D, E, F, and G. The binder resin A is the polyester resin A.

Example 1
[Pre-mixing process]
100 parts by weight of binder resin B and KET. BLUE111 (trade name: copper phthalocyanine 15: 3, manufactured by Clariant) 5.0% by weight (5.7 parts by weight) and paraffin wax (trade name: HNP-10, manufactured by Nippon Seiwa Co., Ltd.) Melting point (Tm): 75 ° C.) 5.0% by weight (5.7 parts by weight) and charge control agent (trade name: Copy Charge N4P VP 2481, manufactured by Clariant Japan KK) 1.5% by weight (1.7) Parts by weight) and a carbodiimide compound (trade name: Carbodilite HMV-8CA, carbodiimide equivalent: 276, manufactured by Nisshinbo Co., Ltd.) 0.43% by weight (0.49 parts by weight). : FM20C, manufactured by Mitsui Mining Co., Ltd.) for 3 minutes to obtain a raw material mixture.

[Melting and kneading process]
20.0 kg of the raw material mixture was melt-kneaded with an open roll type continuous mixer (trade name: MOS320-1800, manufactured by Mitsui Mining Co., Ltd.). The setting conditions of the open roll at this time were a heating roll supply side temperature of 140 ° C., a discharge side temperature of 70 ° C., a cooling roll supply side temperature of 80 ° C., and a discharge side temperature of 25 ° C. As the heating roll and the cooling roll, a roll having a diameter of 320 mm and an effective length of 1550 mm was used, and the gap between the rolls on the supply side and the discharge side was 0.3 mm. The rotation speed of the heating roll was 75 rpm, the rotation speed of the cooling roll was 65 rpm, and the supply amount of the toner raw material was 30 kg / h. The melt-kneaded material of Example 1 was obtained by cooling to room temperature.

[Crushing process]
After the melt-kneaded product was cooled to room temperature, it was roughly pulverized with a cutter mill (trade name: VM-16, manufactured by Orient Corporation).

[Classification process]
Subsequently, the coarsely pulverized product obtained by the coarse pulverization is finely pulverized by a counter jet mill (trade name: AFG, manufactured by Hosokawa Micron Corporation), and then by a rotary classifier (trade name: TSP separator, manufactured by Hosokawa Micron Corporation). The excessively pulverized toner was classified and removed. Thereafter, 0.2 part of hydrophobic silica (trade name: R-974, manufactured by Nippon Aerosil Co., Ltd.) and hydrophobic titanium (trade name: T-805, manufactured by Nippon Aerosil Co., Ltd.) with respect to 100 parts of toner particles. The toner of Example 1 was obtained by adding 0.3 part and mixing with a Henschel mixer (trade name: FM mixer, manufactured by Mitsui Mining Co., Ltd.). The obtained toner had a volume average particle diameter of 6.7 μm.

(Examples 2-28, Comparative Examples 1-24)
The toners of Examples 2 to 14 and Comparative Examples 1 to 12 were treated in the same manner as in Example 1 except that at least one of the addition amount of the carbodiimide compound, the type of binder resin, and the type of carbodiimide compound was different. Obtained.

  The types of binder resins used in Examples 2 to 28 and Comparative Examples 1 to 24 and the amount of carbodiimide compound added are as shown in Tables 2 and 3, respectively.

  In Examples 1-14 and Comparative Examples 1-12, a carbodiimide compound (trade name: Carbodilite HMV-8CA) having an equivalent weight of 276 (g / mol) was used, and in Examples 15-28 and Comparative Examples 13-24, A carbodiimide compound (trade name: Carbodilite LA-1) having an equivalent weight of 247 (g / mol) was used.

  The amount, type and acid value of the binder resin used in the toners obtained in Examples 1 to 28 and Comparative Examples 1 to 24, and the addition of the carbodiimide compounds added in Examples 1 to 28 and Comparative Examples 1 to 24 Tables 2 and 3 summarize the amounts and equivalent percentages of the toners obtained in Examples 1-28 and Comparative Examples 1-24.

<Preparation of two-component developer>
Using the toners of Examples 1 to 28 and Comparative Examples 1 to 24 with respect to the carrier and the ferrite core carrier having a volume average particle diameter of 45 μm, the V-type mixer is adjusted so that the coverage of the toner with respect to the carrier becomes 60%. A two-component developer was prepared by mixing for 20 minutes with a blender (trade name: V-5, manufactured by Tokuju Kogyo Co., Ltd.).

  The toners obtained in Examples 1 to 28 and Comparative Examples 1 to 24 were evaluated for fixability, hydrolyzability, storage stability, charging stability, and light transmittance.

[Fixability]
A two-component developer containing the toners of Examples 1 to 28 and Comparative Examples 1 to 24 is filled into a modified color composite machine (trade name: MX-2700, manufactured by Sharp Corporation), and unfixed in a solid image portion. The amount of toner adhering to the recording paper in the state is adjusted to 0.5 mg / cm ² , and the recording medium (trade name: PPC paper SF-4AM3, manufactured by Sharp Corporation) is used as the recording medium. An unfixed image was formed using a sample image including a rectangular solid image portion of 20 mm and a width of 50 mm. The unfixed image was fixed by an external fixing device manufactured using the fixing unit of the color multifunction peripheral. The fixing process speed was set to 124 mm / second, the temperature of the fixing roller was increased from 130 ° C. in increments of 10 ° C., and a temperature range in which neither low temperature offset nor high temperature offset occurred was obtained, and this was set as a fixing non-offset region. The definition of offset is that the toner does not fix on the recording paper at the time of fixing, but adheres to the recording paper after the roller makes a full rotation, and the upper limit of the fixing non-offset area of the temperature at which the offset occurs. An offset generated at a temperature higher than the above temperature is defined as a high temperature offset, and an offset generated at a temperature lower than the lower limit temperature of the fixing non-offset region is defined as a low temperature offset.

The evaluation criteria for fixability are as follows.
○: Good. The fixing non-offset region is 50 ° C. or higher.
Δ: Yes. The fixing non-offset region is 30 ° C. or higher and lower than 50 ° C.
×: Impossible. The fixing non-offset region is less than 30 ° C.

[Hydrolysis resistance]
0.5 g of the toner obtained in each of Examples 1 to 28 and Comparative Examples 1 to 24 was placed in a molding jig (25 mmΦ), and a simple molding machine (trade name: table press TB-50H, manufactured by NPa System Co., Ltd.) A plate-like sample was produced by pressing at room temperature of 25 ° C. and a pressure of 30 MPa for 1 minute. The weight average molecular weight (Mw) of the sample after storing for 24 hours in a constant temperature and humidity chamber of 80 ° C./85% RH was measured. For the evaluation of hydrolysis resistance, the molecular weight retention rate (%) was used, and the molecular weight retention rate (%) was determined by substituting the measured weight average molecular weight (Mw) into the following formula (5).
Molecular weight retention (%) = (weight average molecular weight after 24 hours / initial weight average molecular weight)
× 100 (5)

The evaluation criteria for hydrolysis resistance are as follows.
○: Good. The molecular weight retention is 90% or more.
Δ: Yes. The molecular weight retention is 80% or more and less than 90%.
×: Impossible. The molecular weight retention is less than 80%.

[Preservation]
30 g of the toners obtained in Examples 1 to 28 and Comparative Examples 1 to 24 were placed in 50 ml plastic bottles, and another similar sample was prepared. The bulk density of the toner of one sample was measured and used as the initial bulk density. The other bottle was placed in a thermostatic chamber at 50 ° C./10% RH with the lid of the plastic bottle closed, taken out after 72 hours, and the bulk density of the toner after 72 hours was measured. The bulk density was measured based on JIS5101-12-1. The bulk density retention rate (%) was used for evaluation of storage stability. The bulk density retention rate (%) was determined by substituting the initial bulk density and the bulk density after 72 hours into the following formula (6). The initial bulk density and the bulk density after 72 hours are compared, and the toner with less fluctuation has better storage stability.
Bulk density retention rate (%) = (bulk density after 72 hours / initial bulk density) × 100 (6)

The evaluation criteria for preservability are as follows.
○: Good. The bulk density retention is 90% or more.
Δ: Yes. The bulk density retention is 80% or more and less than 90%.
×: Impossible. The bulk density retention is less than 80%.

[Charging stability]
5 parts by weight of the toner obtained in Examples 1 to 28 and Comparative Examples 1 to 24 and 95 parts by weight of a ferrite core carrier having a volume average particle diameter of 45 μm are mixed, and a low temperature and low humidity environment having a temperature of 10 ° C. and a relative humidity of 20%. (LL), and left in a high-temperature and high-humidity environment at a temperature of 35 ° C. and a relative humidity of 80% for 24 hours, and then stirred for 30 minutes with a table-top ball mill (manufactured by Tokyo Glass Instrument Co., Ltd.) to prepare a two-component developer. . The obtained two-component developer was prepared by using a charge amount measuring device (trade name: 210HS-2A, manufactured by Trek Japan Co., Ltd.), and mixing a mixture of carrier particles and toner collected from the ball mill with 500 mesh at the bottom. In a metal container equipped with a conductive screen, the toner is sucked with a suction machine at a suction pressure of 250 mmHg, and the weight difference between the weight of the mixture before suction and the weight of the mixture after suction is connected to the container. The toner charge amount was determined from the potential difference between the capacitor electrode plates. A charge amount ratio (HH charge amount / LL charge amount), which is a ratio between the charge amount in a low temperature and low humidity environment and the charge amount in a high temperature and high humidity environment, was calculated.

The evaluation criteria for charging stability are as follows.
○: Good. The charge amount ratio is 80% or more.
Δ: Yes. The charge amount ratio is 70% or more and less than 80%.
×: Impossible. The charge amount ratio is less than 70%.

[Light transmittance of toner]
A two-component developer similar to that for fixing property evaluation is filled into a remodeled color compound machine (trade name: MX-2700, manufactured by Sharp Corporation), resulting in a toner adhesion amount of 1.7 mg / cm ² on the OHP sheet. Images were prepared as follows. The HAZE value of the obtained image was measured using a HAZE meter. The smaller the HAZE value is, the better the light transmittance is, and less than 20 is better, 15 or less is very high transparency and light transmittance is good, and if it is 25 or more, it is practical as a color toner. Judged to lack sex.

The evaluation criteria for light transmittance are as follows.
○: Good. The HAZE value is less than 20.
Δ: Yes. The HAZE value is 20 or more and less than 25.
×: Impossible. The HAZE value is 25 or more.

  Table 4 summarizes the evaluation results of the fixing properties, hydrolysis resistance, storage stability, charging stability, and light transmittance of the toners obtained in Examples 1 to 28.

  Table 5 summarizes the evaluation results of the fixability, hydrolysis resistance, storage stability, charging stability and light transmittance of the toners obtained in Comparative Examples 1 to 24.

  From the results shown in Tables 4 and 5, it is clear that the toners of Examples 1 to 28 are superior to the toners of Comparative Examples 1 to 24 as follows.

  In the toners of Examples 1 to 28, the acid value of the binder resin is 5 mgKOH / g or more and 30 mgKOH / g or less, and the equivalent% satisfies the formula (1), so that the fixing property, hydrolysis resistance, storage stability, Good results were shown in light transmittance and charging stability.

  In Comparative Examples 1, 3, 5, 7, 11, 13, 15, 17, 19, and 23, the addition amount of the carbodiimide compound is not sufficient with respect to the acid value of the binder resin, that is, the crosslinking point is not sufficient. For this reason, elasticity as a toner is insufficient, and good results in high temperature offset resistance cannot be obtained. Moreover, since the crosslinking point was not sufficient, good results were not obtained in hydrolysis resistance.

  In Comparative Examples 9, 10, 21, and 22, the acid value of the binder resin was not sufficient, so the affinity with paper was not sufficient, and good results were not obtained at low temperature offset. In addition, since the crosslinking points are not sufficient, good results were not obtained at high temperature offset.

  In Comparative Examples 11, 12, 23, and 24, since the acid value was too high, good results were not obtained in charging stability.

  Based on the above results, the acid value of the binder resin is the x-axis and the equivalent percentage is the y-axis, and in all of Examples 1 to 28 and Comparative Examples 1 to 24, fixability, hydrolysis resistance, and storage stability. The evaluation results of the charging stability and the light transmission were all plotted as ◯, and the evaluation results including at least one defect were marked as x. Using the upper limit value and lower limit value at which the evaluation results of fixing property, hydrolysis resistance, storage stability, charging stability and light transmittance are all good or acceptable, approximate straight line (A) and approximate straight line (B) Asked. FIG. 4 is a diagram plotting the evaluation results of the toners obtained in Examples 1 to 28 and Comparative Examples 1 to 24 and showing an approximate line (A) and an approximate line (B).

  From the results of FIG. 4, in the range where the value of the x-axis is 5 or more and 30 or less and is surrounded by the approximate line (A) and the approximate line (B), the fixing property, hydrolysis resistance, storage stability, charging It can be seen that the evaluation results of stability and light transmittance are good or acceptable, and the acid value and equivalent percentage of the binder resin should be in this range.

6 is a flowchart illustrating an example of a procedure in a toner manufacturing method according to an exemplary embodiment. 1 is a schematic diagram schematically illustrating a configuration of an image forming apparatus 1 according to an embodiment of the present invention. FIG. 3 is a cross-sectional view schematically showing a configuration of the developing device 20 shown in FIG. 2. It is a figure which plots the evaluation result of the toner obtained in Examples 1-28 and Comparative Examples 1-24, and shows an approximate line (A) and an approximate line (B).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Toner image forming means 3 Transfer means 4 Fixing means 5 Recording material supply means 6 Ejecting means 11 Photosensitive drum 12 Charging means 13 Exposure unit 14 Developing means 15 Cleaning unit 25 Intermediate transfer belt 26 Drive roller 27 Follower roller 28 Intermediate transfer roller 29 Transfer belt cleaning unit 30 Transfer roller 31 Fixing roller 32 Pressure roller 35 Automatic paper feed tray 36 Pickup roller 37 Transport roller 38 Registration roller 39 Manual paper feed tray 40 Discharge roller 41 Discharge tray

Claims (10)

A method for producing a toner comprising at least a binder resin, a colorant and a carbodiimide compound,
The binder resin includes at least a polyester resin, and the acid value of the binder resin is 5 mgKOH / g or more and 30 mgKOH / g or less,
The carbodiimide compound is a compound having two or more carbodiimide groups in the molecule, and the carbodiimide group contained in the carbodiimide compound reacts with the terminal carboxyl group contained in the binder resin to crosslink the binder resin.
Equivalent %, which is the ratio of the equivalent amount of carbodiimide groups, which is the number of moles of carbodiimide groups to 100 g of binder resin, with respect to the equivalent of carboxyl groups, which is the number of moles of carboxyl groups, relative to 100 g of binder resin , satisfies the following formula (1). A method for producing a toner.
−0.78x + 23.9 ≦ y ≦ −2.8x + 94 (1)
(In the formula, x represents the acid value of the binder resin, and y represents the equivalent percentage.) A premixing step of mixing at least a binder resin , a colorant and the carbodiimide compound to obtain a mixture;
A melt-kneading step of melt-kneading the mixture to obtain a melt-kneaded product;
A pulverizing step of pulverizing the melt-kneaded product to obtain a pulverized product;
The toner manufacturing method according to claim 1, further comprising a classification step of classifying the pulverized product. The method for producing a toner according to claim 2 , wherein the binder resin is crosslinked using a carbodiimide compound in the melt-kneading step. Toner characterized in that it is manufactured by the method for producing a toner according to any one of claims 1-3. The toner according to claim 4 , wherein the binder resin includes at least a biomass resin. A developer comprising the toner according to claim 4 . The developer according to claim 6 , wherein the developer is a two-component developer composed of the toner and a carrier. Using a developing agent according to claim 6 or 7, a developing unit, and forming a toner image by developing a latent image formed on the image forming body. An image forming apparatus comprising the developing device according to claim 8 . A toner image forming unit including an image forming body and the developing device, and forming a toner image on the surface of the image forming body;
Transfer means for transferring a toner image to a recording medium;
The recording medium on which the toner image is transferred is passed through a press-contact portion formed by a fixing roller and a pressurizing unit that presses the outer peripheral surface of the fixing roller, so that the toner contained in the toner image is melted by heat. The image forming apparatus according to claim 9 , further comprising a fixing unit that fixes the toner image.

Images