Toner for electrostatic charge image development and method for manufacturing the same

Abstract

To provide a static charge image developing toner that satisfies the resistance to offset, suppresses the inside pollution, and has excellent display qualities, and a method for manufacturing the static charge image developing toner.SOLUTION: The static charge image developing toner of the present invention includes a static charge image developing toner including a toner mother particle including a binder resin and a release agent, the binder resin containing a polymer having a structural unit represented by the following formula (1) and the release agent containing a fatty acid ester [Chemical Formula 1, in which R1 and R2 independently represent an alkyl group of carbon numbers 1 to 8.]SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a toner for electrostatic charge image development and a method for manufacturing the same, and more particularly, to a toner for electrostatic charge image development that satisfies offset resistance, suppresses in-machine contamination, and has excellent image quality.

Background Art

[0002] In the printing field where image formation is performed by an electrophotographic method, in recent years, there has been a demand for a toner for electrostatic charge image development (hereinafter, also simply referred to as "toner") that can cope with reduction of power consumption, speeding up of printing, diversification of image forming media, improvement of image quality, reduction of environmental load, etc. The characteristics required for such a toner include so-called low-temperature fixability, which enables fixing of a toner image at a lower temperature than before, and improvement of fixing strength. Further, not only in the conventional office market but also with the expansion into the light printing market, improvement of the stability of the image quality of printed matter as a product is required.

[0003] Toner usually contains a binder resin having a binder function (hereinafter, also referred to as "toner binder"), and as this binder resin, it is known to use a hybrid resin such as a styrene-acrylic resin, a polyester resin, or a polyester resin having a grafted acrylic polymer segment. Technologies for improving low-temperature fixability and the like by improving these toner binders and the like are known in response to the above requirements (see, for example, Patent Documents 1 to 3). However, particularly at high temperatures such as during toner fixing, since the internal cohesive force of the toner decreases significantly, when the toner comes into contact with a heating member such as a fixing roller during fixing, there has been a problem of occurrence of a hot offset phenomenon in which the fixing member is contaminated.

[0004] In order to suppress the adhesiveness between the fixing member and the toner, a release agent such as a fatty acid ester wax having a low melting viscosity that oozes out at the fixing member-fixing image interface during fixing and can suppress adhesiveness has been added (see, for example, Patent Document 4). However, although the addition of a release agent with a low melting viscosity made it possible to ensure release properties, when the newly melted release agent came into contact with image transfer rollers in the printing machine, etc., there was a problem that the release agent contaminated the transfer members. The contaminants accumulated and reattached to the image, inducing image defects, not only reducing the value of the printed matter as a product, but also often necessitating the disposal of the printed matter.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0006] The present invention has been made in view of the above problems and situations, and the problem to be solved is to provide an electrostatic charge image developing toner that satisfies offset resistance, suppresses in-machine contamination, and has excellent image quality, and a method for manufacturing the same.

Means for Solving the Problems

[0007] In order to solve the above problems, the present inventor, in the process of examining the causes of the above problems, found that by containing a polymer having a specific structural unit as a binder resin and containing a fatty acid ester as a release agent, it is possible to provide an electrostatic charge image developing toner that satisfies offset resistance, suppresses in-machine contamination, and has excellent image quality, and thus arrived at the present invention. That is, the above problems according to the present invention are solved by the following means.

[0008] 1. An electrostatic charge image developing toner containing toner base particles containing a binder resin and a release agent, wherein the binder resin contains a polymer having a structural unit represented by the following general formula (1), The polymer having the structural unit represented by the general formula (1) is a copolymer of a first polymerizable monomer having a structure represented by the following general formula (2) and a second polymerizable monomer copolymerizable with the first polymerizable monomer, and the release agent contains a fatty acid ester and the fatty acid ester is at least one of behenyl behenate and pentaerythritol tetrabehenate The electrostatic charge image developing toner is characterized by the above. [Chemical formula] [In the general formula (1), R 1 and R 2 each independently represent any one of a methyl group, an n-propyl group, an iso-butyl group, and a 2-ethylhexyl group.] [Chemical formula] [In general formula (2), R 1 and R 2 each independently represent any one of a methyl group, an n-propyl group, an iso-butyl group, and a 2-ethylhexyl group.]

[0011] 2 . The content of the structural unit derived from the first polymerizable monomer is in the range of 5 to 40% by mass with respect to 100% by mass of the polymer having the structural unit represented by the general formula (1), which is characterized by the first 1 The electrostatic charge image developing toner according to item.

[0012] 3 . The second polymerizable monomer is characterized by being selected from at least styrenes and the group consisting of acrylic acid esters and methacrylic acid esters, which is characterized by the second 1 Item or the second 2 The electrostatic charge image developing toner according to item.

[0013] 4. The second polymerizable monomer is characterized by being selected from one or more of styrene, acrylic acid, n-butyl acrylate, iso-butyl acrylate, 2-ethylhexyl acrylate, methacrylic acid, and methyl methacrylate, and is the first 3 . The toner for electrostatic charge image development according to item.

[0016] 5 . The content of the release agent is in the range of 5 to 20% by mass with respect to 100% by mass of the polymer having the structural unit represented by the general formula (1), and is the first to the 4 . The toner for electrostatic charge image development according to any one of items up to.

[0017] 6 . From the first to the 5 . A method for manufacturing the toner for electrostatic charge image development according to any one of items up to, . It includes a step of polymerizing the first polymerizable monomer having the structure represented by the general formula (2) to synthesize a polymer having the structural unit represented by the general formula (1) and preparing a binder resin particle dispersion liquid. A method for manufacturing a toner for electrostatic charge image development.

Effect of the Invention

[0020] . By the above means of the present invention, it is possible to suppress in-machine contamination by the release agent while satisfying the offset resistance, and to provide a toner for electrostatic charge image development and a method for manufacturing the same with excellent image quality. . Although the expression mechanism or action mechanism of the effect of the present invention is not clear, it is speculated as follows. The following mechanism is based on speculation, and the present invention is not limited by the following mechanism at all. . In the following description, the polymer having the structural unit represented by the general formula (1) is also simply referred to as "the polymer according to the present invention".

[0021] Conventional toners containing styrene-acrylic resins are composed mainly of structural units derived from styrene, methyl methacrylate, and n-butyl acrylate. In order to suppress the power consumption during printing, so-called low-temperature fixing, such as lowering the Tg (lowering the glass transition temperature) and reducing the molecular weight, has been promoted. On the other hand, with the low-temperature fixing of toners, the release agents used are required to melt at a lower temperature (lower melting point) and have a low melt viscosity (lower melt viscosity). Specifically, fatty acid esters such as behenyl behenate are often used. By lowering the melting point and melt viscosity of such release agents, they become easier to melt during fixing and are more likely to ooze out to the image-fixing roller interface, thereby suppressing the occurrence of offset even when the toner is low-temperature fixed. However, with the lowering of the melting point of the release agent, the crystallization temperature at which it solidifies also becomes lower, so it requires a lot of time to solidify. Here, if it comes into contact with the image transfer roller before solidifying, the release agent migrates to the image transfer roller and causes contamination, resulting in image contamination and significantly deteriorating the image quality. The release agent is also required to solidify (crystallize) early.

[0022] The reason why the toner of the present invention can achieve both hot-offset resistance and good image quality by suppressing image transfer roller contamination can be presumed to be due to the interaction between the toner binder and the fatty acid ester as the release agent. By introducing the polymer having the structural unit represented by the general formula (1) according to the present invention into the toner binder, the dipole interaction with the fatty acid ester, which is a release agent having the same structure, can be enhanced. When the dipole interaction increases, when the fatty acid ester solidifies (crystallizes), the polymer having the structural unit represented by the general formula (1) according to the present invention functions as a scaffold for the crystallization, so that crystal nucleation can be carried out promptly. As a result, it is considered that the time required for solidification can be shortened. Therefore, it can be presumed that even when in contact with the image transfer roller, contamination can be suppressed because solidification has progressed.

Mode for Carrying Out the Invention

[0023] The toner for electrostatic charge image development of the present invention is a toner for electrostatic charge image development containing toner base particles containing a binder resin and a release agent, wherein the binder resin contains a polymer having a structural unit represented by the general formula (1), and the release agent contains a fatty acid ester. This feature is a technical feature common to or corresponding to each of the following embodiments.

[0024] As an embodiment of the present invention, R in the general formula (1) 1 and R 2 each independently represent an alkyl group having 1 to 4 carbon atoms, which is preferable in that machine interior contamination can be more effectively suppressed.

[0025] Further, it is preferable that the polymer having a structural unit represented by the general formula (1) is a copolymer of a first polymerizable monomer having a structure represented by the general formula (2) and a second polymerizable monomer copolymerizable with the first polymerizable monomer, in that the effects of the present invention can be more efficiently exhibited.

[0026] The content of the structural unit derived from the first polymerizable monomer is preferably in the range of 5 to 40% by mass with respect to 100% by mass of the polymer having a structural unit represented by the general formula (1), in that good offset performance can be realized while suppressing roller contamination.

[0027] Further, it is preferable that the second polymerizable monomer is selected from at least styrenes and the group consisting of acrylic acid esters and methacrylic acid esters, and in particular, the second polymerizable monomer is selected from one or more of styrene, acrylic acid, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, methacrylic acid, and methyl methacrylate, in that the glass transition temperature of the polymer according to the present invention can be easily adjusted.

[0028] It is preferable in terms of the interaction with the polymer according to the present invention that the fatty acid ester contains a fatty acid ester within the range of 18 to 24 carbon atoms. In particular, it is preferable that the fatty acid ester within the range of 18 to 24 carbon atoms is at least one of behenyl behenate and pentaerythritol tetrabehenate.

[0029] It is preferable in terms of the balance between fixing property and offset resistance that the content of the mold release agent is within the range of 5 to 20% by mass with respect to 100% by mass of the polymer having the structural unit represented by the general formula (1).

[0030] The method for producing the toner for electrostatic charge image development of the present invention is characterized by having a step of polymerizing a first polymerizable monomer having a structure represented by the general formula (2) to synthesize a polymer having a structural unit represented by the general formula (1) and preparing a binder resin particle dispersion liquid. Thereby, it is possible to produce a toner having good offset resistance, suppressing in-machine contamination by the mold release agent, and having excellent image quality.

[0031] Hereinafter, the present invention, its components, and embodiments and modes for carrying out the present invention will be described. In the present application, "~" is used in the sense of including the numerical values described before and after as the lower limit value and the upper limit value.

[0032] [Toner for Electrostatic Charge Image Development of the Present Invention] The toner for electrostatic charge image development of the present invention (hereinafter, also simply referred to as "toner") is a toner for electrostatic charge image development containing toner base particles containing a binder resin and a mold release agent, wherein the binder resin contains a polymer having a structural unit represented by the following general formula (1), and the mold release agent contains a fatty acid ester.

[0033] In this specification, the "toner base particle" constitutes the base of the "toner particle". The "toner base particle" contains at least a binder resin and a release agent, and may contain other components such as a colorant and a charge control agent as required. The "toner base particle" is referred to as a "toner particle" by adding an external additive. And the "toner" refers to an aggregate of "toner particles".

[0034] <Binder resin> The binder resin according to the present invention contains a polymer having a structural unit represented by the following general formula (1).

[0035] [Chemical formula] [In the general formula (1), R 1 and R 2 each independently represents an alkyl group having 1 to 8 carbon atoms.]

[0036] (Polymer having a structural unit represented by the general formula (1)) R in the general formula (1) 1 and R 2 are each independently an alkyl group having 1 to 8 carbon atoms. Specific examples thereof include, for example, a methyl group, an n-butyl group, an iso-butyl group, a 2-ethylhexyl group, etc. From the viewpoint of further suppressing the contamination of the image carrier roller, R 1 and R 2 are preferably alkyl groups having 1 to 4 carbon atoms.

[0037] The polymer having a structural unit represented by the general formula (1) can be synthesized by polymerizing a monomer having a structure represented by the following general formula (2) (hereinafter, also referred to as the "first polymerizable monomer").

[0038] [Chemical formula] [In the general formula (2), R 1 and R 2Each independently represents an alkyl group having 1 to 8 carbon atoms.

[0039] R 1 and R 2 are synonymous with R 1 and R 2 in the general formula (1). The first polymerizable monomer can be used alone or in combination of two or more. Specific examples of the first polymerizable monomer include, but are not limited to, the following exemplified compounds M1 to M7.

[0040]

Chemical formula

[0041] As the first polymerizable monomer, a commercially available product or a synthetic product may be used. As an example of the synthesis method, the first polymerizable monomer can also be obtained by a condensation reaction of itaconic acid as a starting material with predetermined alcohols.

[0042] Further, the content of the structural unit derived from the first polymerizable monomer is preferably in the range of 5 to 50% by mass, more preferably in the range of 5 to 40% by mass, based on 100% by mass of the polymer having the structural unit represented by the general formula (1).

[0043] The polymerization method of the first polymerizable monomer is not particularly limited, but from the viewpoint of easy synthesis, a method of radical polymerizing the monomer using a known oil-soluble or water-soluble radical polymerization initiator is preferred.

[0044] That is, the method for producing a toner according to a preferred embodiment of the present invention is a method for producing an electrostatic charge image developing toner containing a binder resin containing a polymer having a structural unit represented by the general formula (1) and a release agent containing a fatty acid ester. The method includes performing (radical) polymerization of a polymerizable monomer having a structure represented by the general formula (2) to synthesize a polymer having a structural unit represented by the general formula (1), and preparing a binder resin particle dispersion. It is also preferable to further include a step of preparing a release agent particle dispersion containing a release agent, and a step of mixing the binder resin particle dispersion and the release agent particle dispersion.

[0045] Specific examples of the oil-soluble polymerization initiator used for radical polymerization include azo-based or diazo-based polymerization initiators and peroxide-based polymerization initiators shown below. If necessary, known chain transfer agents such as n-octyl mercaptan and n-octyl 3-mercaptopropionate may be used.

[0046] Examples of azo-based or diazo-based polymerization initiators include 2,2'-azobis-(2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobisisobutyronitrile, and the like.

[0047] Examples of peroxide-based polymerization initiators include benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxydicarbonate, cumene hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide, dicumyl peroxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide, 2,2-bis-(4,4-t-butylperoxycyclohexyl)propane, tris-(t-butylperoxy)triazine, and the like.

[0048] In addition, when forming a polymer having a structural unit represented by the general formula (1) according to the present invention by an emulsion polymerization method, a water-soluble radical polymerization initiator can be used. Examples of the water-soluble radical polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate, azobisaminodipropanoate, azobiscyanovaleric acid and its salts, hydrogen peroxide, and the like. The polymerization temperature varies depending on the types of monomers and polymerization initiators used, but it is preferably in the range of 50 to 100 °C, more preferably in the range of 55 to 90 °C. Also, the polymerization time varies depending on the types of monomers and polymerization initiators used, but for example, it is preferably 1 to 12 hours.

[0049] (Polymer having other structural units) The polymer having the structural unit represented by the general formula (1) according to the present invention may be a polymer obtained only from the polymerizable monomer (first polymerizable monomer) having the structure represented by the general formula (2). However, from the viewpoint of more efficiently exerting the effects of the present invention, it is preferably a copolymer with another polymerizable monomer copolymerizable with the first polymerizable monomer as described below (also referred to as "second polymerizable monomer").

[0050] Examples of the second polymerizable monomer include styrene-based monomers (styrenes) such as styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, o-acetoxystyrene, m-acetoxystyrene, p-acetoxystyrene; acrylate esters such as methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, tert-butyl acrylate, isobutyl acrylate (iso-butyl acrylate), n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, phenyl acrylate; methacrylate esters such as methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate; and the like. Among these, from the viewpoint of facilitating the adjustment of the glass transition temperature of the polymer, at least one selected from styrenes and acrylate esters is preferable, at least one selected from the group consisting of styrene, acrylic acid, n-butyl acrylate, iso-butyl acrylate, 2-ethylhexyl acrylate, methacrylic acid, and methyl methacrylate is more preferable, and at least one of styrene and n-butyl acrylate is even more preferable.

[0051] Furthermore, as the second polymerizable monomer, a polymerizable monomer having an ionic dissociable group may be used. The polymerizable monomer having an ionic dissociable group has a group such as a carboxy group, a sulfonic acid group, or a phosphoric acid group. Specifically, acrylic acid, methacrylic acid, maleic acid, itaconic acid, fumaric acid, and the like can be mentioned. Among these, acrylic acid or methacrylic acid is preferable. These second polymerizable monomers can be used alone or in combination of two or more.

[0052] In the polymer according to the present invention, the content of the structural unit derived from the second polymerizable monomer is not particularly limited and can be appropriately adjusted depending on the type of the structural unit. For example, when the second polymerizable monomer is the above-mentioned styrenic monomer, the content of the structural unit derived from the styrenic monomer in the polymer is preferably in the range of 20 to 80% by mass, more preferably in the range of 30 to 70% by mass, based on 100% by mass of all the structural units of the polymer.

[0053] When the second polymerizable monomer is an acrylate or a methacrylate, the content of the structural unit derived from the acrylate or the methacrylate in the polymer is preferably in the range of 5 to 50% by mass, more preferably in the range of 10 to 40% by mass, based on 100% by mass of all the structural units of the polymer.

[0054] When a polymerizable monomer having an ionic dissociable group is used, the content of the structural unit is preferably in the range of 3 to 8% by mass, based on 100% by mass of all the structural units of the polymer according to the present invention.

[0055] The method for synthesizing the polymer according to the present invention using the first polymerizable monomer and the second polymerizable monomer is the same as the polymerization method of the first polymerizable monomer described above, and thus the description thereof is omitted here.

[0056] The polymer according to the present invention preferably has a peak molecular weight obtained from the molecular weight distribution in terms of polystyrene measured by gel permeation chromatography (GPC) in the range of 3500 to 35000, more preferably in the range of 10000 to 30000. A peak molecular weight in such a range is preferable because the polymer has an appropriate melt viscosity during fixing and can achieve both good fixing property and offset resistance.

[0057] The peak molecular weight is the molecular weight corresponding to the elution time at the peak top in the molecular weight distribution. When there are multiple peaks in the molecular weight distribution, it refers to the molecular weight corresponding to the elution time at the peak top with the largest peak area ratio.

[0058] The peak molecular weight of the polymer can be measured by the following method. Specifically, using the apparatus "HLC-8220" (manufactured by Tosoh Corporation) and the column "TSKguardcolumn + TSKgel SuperHZM-M3 series" (manufactured by Tosoh Corporation), while maintaining the column temperature at 40°C, flowing tetrahydrofuran (THF) as the carrier solvent at a flow rate of 0.2 ml / min, and dissolving the measurement sample in tetrahydrofuran to a concentration of 1 mg / ml under dissolution conditions where it is treated with an ultrasonic disperser for 5 minutes at room temperature (25°C). Next, it is treated with a membrane filter with a pore size of 0.2 μm to obtain a sample solution. 10 μl of this sample solution is injected into the apparatus together with the above carrier solvent, detected using a refractive index detector (RI detector), and measured from the molecular weight distribution of the measurement sample.

[0059] From the perspective of the balance between fixability and offset resistance, the content ratio of the polymer according to the present invention is preferably in the range of 65 to 99% by mass, more preferably in the range of 70 to 97% by mass, and even more preferably in the range of 75 to 95% by mass, with the total mass of the binder resin being 100% by mass.

[0060] The binder resin according to the present invention may contain other resins other than the polymer according to the present invention, and resins generally used as binder resins constituting toner can be used without limitation. Specifically, for example, polyester resins, silicone resins, polyolefin resins, polyamide resins, or epoxy resins can be mentioned. These other resins can be used alone or in combination of two or more.

[0061] Hereinafter, the polyester resin that can be used as the binder resin will be described. (Polyester resin) The polyester resin is a known polyester resin obtained by a polycondensation reaction of a dicarboxylic acid having a valence of 2 or more (polyvalent carboxylic acid component) and an alcohol having a valence of 2 or more (polyvalent alcohol component). Note that the polyester resin may be amorphous or crystalline.

[0062] As the valences of the polyvalent carboxylic acid component and the polyvalent alcohol component, they are preferably 2 to 3 respectively, and particularly preferably 2 respectively. Therefore, as a particularly preferred form, the case where the valences are both 2 (that is, the dicarboxylic acid component and the diol component) will be described.

[0063] Examples of the dicarboxylic acid component include saturated aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid (dodecanedioic acid), 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,13-tridecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,16-hexadecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid; unsaturated aliphatic dicarboxylic acids such as methylene succinic acid, fumaric acid, maleic acid, 3-hexenedioic acid, 3-octenedioic acid, dodecenyl succinic acid; unsaturated aromatic dicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, t-butylisophthalic acid, tetrachlorophthalic acid, chlorophthalic acid, nitrophthalic acid, p-phenylenediacetic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, anthracenedicarboxylic acid; etc. are included, and lower alkyl esters and acid anhydrides of these can also be used. The dicarboxylic acid component may be used alone or in a mixture of two or more. In addition, polyvalent carboxylic acids having a valence of 3 or more such as trimellitic acid and pyromellitic acid, anhydrides of the above carboxylic acid compounds, or alkyl esters having 1 to 3 carbon atoms can also be used.

[0064] Examples of the diol component include saturated aliphatic diols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, 1,20-eicosanediol, neopentyl glycol; unsaturated aliphatic diols such as 2-butene-1,4-diol, 3-butene-1,4-diol, 2-butyne-1,4-diol, 3-butyne-1,4-diol, 9-octadecene-7,12-diol; bisphenols such as bisphenol A and bisphenol F, and alkylene oxide adducts of these bisphenols such as ethylene oxide adducts and propylene oxide adducts, i.e., aromatic diols. Derivatives of these can also be used. The diol component may be used alone or as a mixture of two or more.

[0065] The method for producing the polyester resin is not particularly limited, and it can be produced by polycondensing (esterifying) the above polyvalent carboxylic acid component and polyhydric alcohol component using a known esterification catalyst.

[0066] Examples of the catalyst that can be used in the production of the polyester resin include alkali metal compounds such as sodium and lithium; compounds containing Group 2 elements such as magnesium and calcium; compounds of metals such as aluminum, zinc, manganese, antimony, titanium, tin, zirconium, and germanium; phosphorous acid compounds; phosphoric acid compounds; and amine compounds. Specifically, examples of the tin compound include dibutyltin oxide (dibutyltin monoxide), tin octylate, dioctyltin, and salts thereof.

[0067] Examples of the titanium compound include tetra-n-butyl titanate (Ti(O-n-Bu) 4) Titanium alkoxides such as tetraisopropyl titanate, tetramethyl titanate, and tetrastearyl titanate; titanium acylates such as polyhydroxy titanium stearate; titanium chelates such as titanium tetraacetylacetonate, titanium lactate, and titanium triethanolamine, etc. can be mentioned. Examples of the germanium compound include germanium dioxide and the like. Furthermore, examples of the aluminum compound include polyaluminum hydroxide, aluminum alkoxide, tributylaluminate, etc. These may be used alone or in combination of two or more.

[0068] The polymerization temperature is not particularly limited, but it is preferably in the range of 70 to 250 °C. Also, the polymerization time is not particularly limited, but it is preferably 0.5 to 10 hours. During the polymerization, the inside of the reaction system may be depressurized as necessary.

[0069] The above polyester resin may be a hybrid polyester resin having a graft copolymer structure of a polyester polymerization segment and a styrene-acrylic polymerization segment graft.

[0070] <Release agent> The toner base particles according to the present invention contain a release agent, and the release agent contains a fatty acid ester. Examples of fatty acid esters contained in the release agent include, for example, behenyl behenate (behenyl behenate), stearyl stearate (stearyl stearate), behenyl stearate, stearyl behenate, butyl stearate, propyl oleate, hexadecyl palmitate (hexadecyl palmitate), methyl lignocerate (methyl lignocerate), glycerin monostearate (glyceryl stearate), diglyceryl distearate (diglyceryl distearate), pentaerythritol tetrabehenate (pentaerythritol tetrabehenate ester), diethylene glycol monostearate, dipropylene glycol distearate, sorbitan monostearate, cholesteryl stearate, trimethylolpropane tribehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, tristearyl trimellitate (tristearyl trimellitate), distearyl maleate, methyl triacontanate (methyl triacontanate), and the like. These fatty acid esters can be used alone or in combination of two or more. In addition, these fatty acid esters may be commercially available products or synthetic products.

[0071] From the perspective of the interaction with the polymer according to the present invention, the fatty acid ester preferably contains a fatty acid ester within the range of 18 to 24 carbon atoms. Examples of such fatty acids include stearic acid, arachidic acid, behenic acid, lignoceric acid, and the like. A more preferable release agent is at least one of behenyl behenate (behenyl behenate) and pentaerythritol tetrabehenate (pentaerythritol tetrabehenate ester).

[0072] If the release agent contains a fatty acid ester, it may also contain other waxes other than the fatty acid ester. Examples of such other waxes include, for example, polyolefin waxes such as low molecular weight polyethylene and low molecular weight polypropylene, branched hydrocarbon waxes such as microcrystalline wax, long chain hydrocarbon waxes such as paraffin wax and Sasol wax, dialkyl ketone waxes such as distearyl ketone, fatty acid amide waxes such as ethylenediamine behenamide and trisstearylamide trimellitate, and the like.

[0073] From the viewpoint of the balance between fixability and offset resistance, the content ratio of the release agent is preferably in the range of 1 to 25% by mass, more preferably in the range of 5 to 20% by mass, based on 100% by mass of the total mass of the polymer according to the present invention.

[0074] The toner base particles used in the present invention may contain a colorant and a charge control agent, if necessary.

[0075] <Colorant> The toner base particles according to the present invention may contain a colorant. As the colorant, generally known dyes and pigments can be used.

[0076] Examples of the colorant for obtaining a black toner include carbon black, magnetic materials, iron-titanium composite oxide black, etc. Examples of carbon black include channel black, furnace black, acetylene black, thermal black, lamp black, etc. Examples of magnetic materials include ferrite, magnetite, etc.

[0077] Examples of the colorant for obtaining a yellow toner include dyes such as C.I. Solvent Yellow 19, 44, 77, 79, 81, 82, 93, 98, 103, 104, 112, 162; pigments such as C.I. Pigment Yellow 14, 17, 74, 93, 94, 138, 155, 180, 185.

[0078] Examples of colorants for obtaining magenta toner include dyes such as C.I. Solvent Red 1, 49, 52, 58, 63, 111, 122; and pigments such as C.I. Pigment Red 5, 48:1, 53:1, 57:1, 122, 139, 144, 149, 166, 177, 178, 222.

[0079] Examples of colorants for obtaining cyan toner include dyes such as C.I. Solvent Blue 25, 36, 60, 70, 93, 95; and pigments such as C.I. Pigment Blue 1, 7, 15, 60, 62, 66, 76.

[0080] For each color of toner, one or more colorants can be used in combination. The content ratio of the colorant is preferably in the range of 0.5 to 20% by mass, more preferably in the range of 2 to 10% by mass, based on 100% by mass of the total mass of the toner base particles.

[0081] <Charge control agent> The toner base particles according to the present invention may contain a charge control agent. The charge control agent used is a substance that can give positive or negative charge by triboelectrification, and is not particularly limited as long as it is colorless, and various known positive charge control agents and negative charge control agents can be used.

[0082] Specifically, examples of the positive charge control agent include nigrosine dyes such as "Nigrosine Base EX" (manufactured by Orient Chemical Industries, Ltd.), quaternary ammonium salts such as "Quaternary Ammonium Salt P-51" (manufactured by Orient Chemical Industries, Ltd.), "Copy Charge PX VP435" (manufactured by Hoechst Japan), alkoxylated amines, alkylamides, molybdate chelate pigments, and imidazole compounds such as "PLZ1001" (manufactured by Shikoku Kasei Kogyo Co., Ltd.).

[0083] In addition, examples of the negatively charge control agent include metal complexes such as "Bontron (registered trademark) S-22", "Bontron (registered trademark) S-34", "Bontron (registered trademark) E-81", "Bontron (registered trademark) E-84" (manufactured by Orient Chemical Industries, Ltd.), "Spiro Black TRH" (manufactured by Hodogaya Chemical Co., Ltd.), thioindigo-based pigments, quaternary ammonium salts such as "Copy Charge NX VP434" (manufactured by Hoechst Japan), calixarene compounds such as "Bontron (registered trademark) E-89" (manufactured by Orient Chemical Industries, Ltd.), boron compounds such as "LR147" (manufactured by Nippon Carlit Co., Ltd.), and fluorine compounds such as magnesium fluoride and carbon fluoride.

[0084] As the metal complex used as the negatively charge control agent, in addition to those shown above, metal complexes having various structures such as oxycarboxylic acid metal complexes, dicarboxylic acid metal complexes, amino acid metal complexes, diketone metal complexes, diamine metal complexes, azo group-containing benzene-benzene derivative skeleton metal complexes, and azo group-containing benzene-naphthalene derivative skeleton metal complexes can be used.

[0085] By configuring the toner base particles to contain the charge control agent in this way, the chargeability of the toner is improved. The content ratio of the charge control agent is preferably in the range of 0.01 to 30% by mass, more preferably in the range of 0.1 to 10% by mass in the toner base particles.

[0086] The form of the toner base particles according to the present invention is not particularly limited, and can take forms such as a so-called single-layer structure (a homogeneous structure that is not a core-shell type), a core-shell structure, a multilayer structure of three or more layers, a domain-matrix structure, etc.

[0087] <External additive> In order to improve the fluidity, chargeability, cleaning property, etc. of the toner, external additives such as fluidizing agents and cleaning aids, which are so-called post-treatment agents, may be added to the toner base particles to constitute the toner of the present invention.

[0088] Examples of the external additive include inorganic particles such as silica particles, alumina particles, and titanium oxide particles; inorganic stearic acid compound particles such as aluminum stearate particles and zinc stearate particles; and inorganic titanate compound particles such as strontium titanate particles and zinc titanate particles. These can be used alone or in combination of two or more. These inorganic particles may be surface-treated with a silane coupling agent, a titanium coupling agent, a higher fatty acid, silicone oil, etc. to improve heat-resistant storage stability and environmental stability.

[0089] The addition amount of the external additive is preferably in the range of 0.05 to 5 parts by mass, more preferably in the range of 0.1 to 3 parts by mass, based on 100 parts by mass of the toner base particles.

[0090] <Average particle size of toner> The average particle size of the toner is preferably in the range of 4 to 10 μm, more preferably in the range of 5 to 9 μm, in terms of the volume-based median diameter (D 50 ). When the volume-based median diameter (D 50 ) is within the above range, the transfer efficiency is increased, the halftone image quality is improved, and the image quality of thin lines, dots, etc. is improved.

[0091] In the present invention, the volume-based median diameter (D 50 ) of the toner is measured and calculated using a measuring device connected to a computer system (manufactured by Beckman Coulter, Inc.) equipped with data processing software "Software V3.51" on a "Coulter Counter 3" (manufactured by Beckman Coulter, Inc.). Specifically, 0.02 g of a measurement sample (toner) is added to 20 mL of a surfactant solution (for example, a surfactant solution obtained by diluting a neutral detergent containing a surfactant component 10 times with pure water for the purpose of dispersing toner particles), and after allowing it to dissolve, ultrasonic dispersion is performed for 1 minute to prepare a toner dispersion. This toner dispersion is pipetted into a beaker containing "ISOTON II" (manufactured by Beckman Coulter, Inc.) in a sample stand until the display concentration of the measuring device reaches 8%. Here, by setting the concentration range in this way, reproducible measurement values can be obtained. Then, in the measuring device, the number of measured particles is set to 25,000, the aperture diameter is set to 50 μm, and the frequency values are calculated by dividing the measurement range of 1 to 30 μm into 256 parts, and the particle diameter at which 50% of the particles from the larger volume integration fraction is the median diameter (D 50 ) based on volume is determined.

[0092] [Method for manufacturing toner] The method for manufacturing the toner of the present invention is characterized by having a step of polymerizing a first polymerizable monomer having a structure represented by the general formula (2), synthesizing a polymer having a structural unit represented by the general formula (1), and preparing a binder resin particle dispersion. Further, the method for manufacturing the toner of the present invention only needs to have a step of preparing the binder resin particle dispersion, and the others are not particularly limited. For example, the polymer, release agent, and optionally a colorant, etc. according to the present invention are melt-kneaded, and then pulverized, classified, etc. to obtain a toner. Further, polymer particles are prepared by emulsion polymerization, mini-emulsion polymerization, etc. of a polymerizable monomer in an aqueous medium, and a toner can be obtained by an emulsion aggregation method in which the dispersed particles such as the polymer particles, release agent particles, and optionally colorant particles are aggregated and fused. As the emulsion aggregation method, the methods described in JP-A-5-265252, JP-A-6-329947, JP-A-9-15904, etc. can be adopted. Furthermore, a manufacturing method using the suspension polymerization method described in JP-A-2010-191043 may also be used.

[0093] Among them, from the viewpoint that it is easy to control the particle size and shape and the energy cost during production can be reduced, a production method using an emulsification aggregation method is preferable. A production method using such an emulsification aggregation method (1A) A binder resin particle dispersion preparation step of preparing a dispersion of binder resin particles (1B) A colorant particle dispersion preparation step of preparing a dispersion of colorant particles (1C) A release agent particle dispersion preparation step of preparing a dispersion of release agent particles (2) An aggregation step of adding a flocculant to an aqueous medium in which binder resin particles, colorant particles, and release agent particles are present, allowing salting out to proceed, and simultaneously performing aggregation and fusion to form aggregated particles (3) An aging step of forming toner particles by controlling the shape of the aggregated particles (4) A filtration and washing step of filtering the toner particles from the aqueous medium and removing surfactants and the like from the toner particles (5) A drying step of drying the washed toner particles (6) An external additive addition step of adding an external additive to the dried toner particles preferably includes each of the steps. Hereinafter, the steps (1A) to (1C) will be described.

[0094] (1A) Binder resin particle dispersion preparation step In this step, resin particles are formed by conventionally known emulsion polymerization or the like, and these resin particles are aggregated and fused to form binder resin particles. As an example, polymerizable monomers (the first polymerizable monomer and the second polymerizable monomer) constituting the binder resin are introduced into and dispersed in an aqueous medium, and these polymerizable monomers are polymerized by a polymerization initiator to synthesize a polymer having a structural unit represented by the general formula (1) according to the present invention, and a dispersion of binder resin particles is prepared.

[0095] In addition to the method of polymerizing a polymerizable monomer with a polymerization initiator in the above aqueous medium as a method for obtaining a binder resin particle dispersion, for example, a method of performing a dispersion treatment in an aqueous medium without using a solvent, or a method of dissolving a polymer in an organic solvent such as ethyl acetate to form a solution, emulsifying and dispersing the solution in an aqueous medium using a disperser, and then performing a solvent removal treatment can be mentioned. At this time, if necessary, the binder resin may be preliminarily contained with a release agent. Further, for dispersion, it is also preferable to polymerize in the presence of a known surfactant (for example, an anionic surfactant such as sodium polyoxyethylene (2) dodecyl ether sulfate, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate). The volume-based median diameter of the binder resin particles in the dispersion is preferably in the range of 50 to 300 nm. The volume-based median diameter of the binder resin particles in the dispersion can be measured by the dynamic light scattering method using "Microtrac UPA-150" (manufactured by Nikkiso Co., Ltd.).

[0096] (1B) Colorant particle dispersion preparation step This colorant particle dispersion preparation step is a step of dispersing a colorant in fine particle form in an aqueous medium to prepare a dispersion of colorant particles. The dispersion of the colorant can be performed using mechanical energy. The volume-based median diameter of the colorant particles in the dispersion is preferably in the range of 10 to 300 nm, and more preferably in the range of 50 to 200 nm. The volume-based median diameter of the colorant particles in the dispersion can be measured by the dynamic light scattering method using "Microtrac UPA-150" (manufactured by Nikkiso Co., Ltd.) in the same manner as above.

[0097] (1C) Release agent particle dispersion preparation step This release agent particle dispersion preparation step is a step of dispersing the release agent according to the present invention containing a fatty acid ester in fine particle form in an aqueous medium to prepare a dispersion of release agent particles. The release agent can be dispersed using mechanical energy. The volume-based median diameter of the release agent particles in the dispersion is preferably in the range of 100 to 1000 nm, more preferably in the range of 200 to 700 nm. The volume-based median diameter of the release agent particles in the dispersion can be measured, for example, by a laser diffraction particle size distribution analyzer LA-750 (manufactured by Horiba, Ltd.).

[0098] (aqueous medium) (1A) to (1C) The aqueous medium used in the steps is water, or an aqueous medium having water as the main component (50% by mass or more) and containing optional components such as water-soluble solvents such as alcohols and glycols, surfactants, and dispersants. Preferably, an aqueous medium obtained by mixing water and a surfactant is used.

[0099] Examples of the above water-soluble solvents include methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, tetrahydrofuran, etc. Among these, alcohols such as methanol, ethanol, isopropanol, and butanol, which are organic solvents that do not dissolve the polymer, are preferred.

[0100] Examples of surfactants include cationic surfactants, anionic surfactants, nonionic surfactants, etc. Examples of cationic surfactants include dodecylammonium chloride, dodecylammonium bromide, dodecyltrimethylammonium bromide, dodecylpyridinium chloride, dodecylpyridinium bromide, hexadecyltrimethylammonium bromide, etc. Examples of anionic surfactants include fatty acid soaps such as sodium stearate and sodium dodecanoate, sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, etc. Examples of nonionic surfactants include polyoxyethylene dodecyl ether, polyoxyethylene hexadecyl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene lauryl ether, polyoxyethylene sorbitan monooleate ether, monodecanoyl sucrose, etc. Such surfactants can be used alone or in combination of two or more. Among the surfactants, anionic surfactants are preferred, and sodium dodecylbenzenesulfonate and sodium dodecyl sulfate are more preferably used. The addition amount of the surfactant is preferably in the range of 0.01 to 10 parts by mass, more preferably in the range of 0.04 to 2 parts by mass, based on 100 parts by mass of the aqueous medium.

[0101] (2) The steps from the aggregation step to the external additive addition step (6) can be carried out according to various conventionally known methods. The flocculant used in the (2) aggregation step is not particularly limited, but those selected from metal salts are preferably used.

[0102] Examples of metal salts include monovalent metal salts such as salts of alkali metals such as sodium, potassium, and lithium; divalent metal salts such as calcium, magnesium, manganese, and copper; trivalent metal salts such as iron and aluminum. Specific metal salts include sodium chloride, potassium chloride, lithium chloride, calcium chloride, magnesium chloride, zinc chloride, copper sulfate, magnesium sulfate, manganese sulfate, polyaluminum chloride, etc. Among these, since aggregation can proceed with a smaller amount, it is particularly preferable to use divalent or trivalent metal salts. These can be used alone or in combination of two or more kinds.

[0103] [Developer] When the toner of the present invention contains a magnetic material and is used as a one-component magnetic toner, when it is mixed with a so-called carrier and used as a two-component developer, when a non-magnetic toner is used alone, etc. are conceivable, and it can be suitably used in any case. As the magnetic material, for example, magnetite, γ - hematite, or various ferrites can be used.

[0104] As the carrier constituting the two-component developer, magnetic particles made of conventionally known materials such as metals such as iron, steel, nickel, cobalt, ferrite, magnetite, and alloys of these metals with metals such as aluminum and lead can be used.

[0105] As the carrier, it is preferable to use a coated carrier in which the surface of the magnetic particles is coated with a coating agent such as resin, or a so-called resin-dispersed carrier in which magnetic powder is dispersed in a binder resin. The resin for coating is not particularly limited, and for example, olefin resin, styrene resin, styrene-acrylic resin, silicone resin, polyester resin, or fluororesin is used. Also, the resin for constituting the resin-dispersed carrier is not particularly limited, and known resins can be used. For example, acrylic resin, styrene-acrylic resin, polyester resin, fluororesin, phenol resin, etc. can be used.

[0106] The median diameter of the carrier based on volume is preferably in the range of 20 to 100 μm, more preferably in the range of 25 to 60 μm. The median diameter of the carrier based on volume can typically be measured by a laser diffraction particle size distribution measuring device "HELOS" (manufactured by SYMPATEC) equipped with a wet disperser.

[0107] The mixing amount of the toner with respect to the carrier is preferably in the range of 2 to 10% by mass, with the total mass of the toner and the carrier being 100% by mass.

[0108] [Image forming method] The toner of the present invention can be suitably used in an image forming method including a fixing step by a thermal pressure fixing method capable of applying pressure and heating. In particular, it can be suitably used in an image forming method in which the fixing temperature in the fixing step is a relatively low fixing temperature in the range of 80 to 110 °C, preferably 80 to 95 °C, at the surface temperature of the heating member in the fixing nip portion. Furthermore, it can also be suitably used in a high-speed fixing image forming method in which the fixing linear speed is in the range of 200 to 600 mm / sec.

[0109] In this image forming method, specifically, using the toner of the present invention as described above, for example, an electrostatic charge image formed on a photoreceptor is developed to obtain a toner image, and this toner image is transferred to an image support. Then, the toner image transferred onto the image support is fixed to the image support by a fixing process of the thermal pressure fixing method, thereby obtaining a printed matter on which a visible image is formed.

[0110] Also, the toner of the present invention can be used in a monochrome image forming method or a full-color image forming method. In a full-color image forming method, it can be applied to any image forming method such as a four-cycle image forming method composed of four color developing devices respectively related to yellow, magenta, cyan, and black and one photoreceptor, or a tandem image forming method in which image forming units having color developing devices and photoreceptors respectively related to each color are mounted separately for each color.

Example

[0111] Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In the following examples, unless otherwise specified, the operations were carried out at room temperature (25°C). Also, unless otherwise specified, “%” and “parts” respectively mean “mass %” and “parts by mass”.

[0112] The peak molecular weight of the polymer contained in the binder resin was measured as follows. The measurement results are shown in Table I below. Using the apparatus “HLC-8220” (manufactured by Tosoh Corporation) and the column “TSKguardcolumn+TSKgelSuperHZM-M3 series” (manufactured by Tosoh Corporation), while maintaining the column temperature at 40°C, tetrahydrofuran (THF) was flowed as a carrier solvent at a flow rate of 0.2 ml / min, and the measurement sample was dissolved in tetrahydrofuran to a concentration of 1 mg / ml under dissolution conditions where it was treated for 5 minutes using an ultrasonic disperser at room temperature (25°C). Next, it was treated with a membrane filter having a pore size of 0.2 μm to obtain a sample solution. 10 μl of this sample solution was injected into the apparatus together with the above carrier solvent, detected using a refractive index detector (RI detector), and determined from the molecular weight distribution of the measurement sample.

[0113] [Manufacture of Toner 1] <Preparation of Binder Resin Particle Dispersion Liquid 1> An aqueous surfactant solution prepared by dissolving 8 g of sodium dodecyl sulfate in 3 L of ion-exchanged water was charged into a 5 L stainless steel kettle (SUS kettle) equipped with a stirrer, a temperature sensor, a condenser tube, and a nitrogen introduction device, and while stirring at a stirring speed of 230 rpm under a nitrogen stream, the liquid temperature was raised to 80°C. To this surfactant solution, an initiator solution prepared by dissolving 10 g of potassium persulfate in 200 g of ion-exchanged water was added. After setting the temperature to 80 °C, the following monomer mixture was added dropwise over 100 minutes, and the system was heated and stirred at 80 °C for 2 hours to carry out polymerization, thereby preparing a binder resin particle dispersion 1: - Monomer mixture - Exemplified compound M1 (refer to the above-exemplified compound, in the general formula (2), R 1 and R 2 are methyl groups (denoted as "Me" in Table I below)) 161 g Styrene (St) 411 g n-Butyl acrylate (nBA) 177 g Methacrylic acid (MAA) 40 g Acrylic acid (AA) 16 g n-Octyl 3-mercaptopropionate 5.5 g When the volume-based median diameter of the binder resin particles in the obtained binder resin particle dispersion 1 was measured by the dynamic light scattering method using "Microtrac UPA-150" (manufactured by Nikkiso Co., Ltd.), it was 125 nm.

[0114] <Preparation of Colorant Particle Dispersion 1> Colorant: Carbon black (Mogul (registered trademark) L, manufactured by Cabot Corporation) 10 parts by mass Anionic surfactant (20% aqueous solution of sodium dodecylbenzenesulfonate) 1.5 parts by mass Ion-exchanged water 90 parts by mass The above components were mixed and dispersed using an SC mill to obtain a colorant particle dispersion 1. When the volume-based median diameter of the colorant particles in the dispersion was measured by the dynamic light scattering method using "Microtrac UPA-150" (manufactured by Nikkiso Co., Ltd.), it was 155 nm.

[0115] <Preparation of Release Agent Particle Dispersion 1> Behenyl behenate 100 parts by mass Sodium dodecyl sulfate 5 parts by mass 240 parts by mass of ion-exchanged water The above components were dispersed in a round stainless steel flask using a homogenizer "Ultra Turrax (registered trademark) T50" (manufactured by IKA Corporation) for 10 minutes, and then subjected to dispersion treatment with a pressure discharge type homogenizer to obtain a mold release agent particle dispersion liquid 1. When the volume-based median diameter of the mold release agent particles in the dispersion liquid was measured with a laser diffraction particle size distribution analyzer LA-750 (manufactured by Horiba, Ltd.), it was 530 nm.

[0116] <Preparation of Toner Base Particle Dispersion Liquid 1> 237 parts by mass of binder resin particle dispersion liquid 1 42 parts by mass of colorant particle dispersion liquid 1 18 parts by mass of mold release agent particle dispersion liquid 1 1.8 parts by mass of polyaluminum chloride 600 parts by mass of ion-exchanged water The above components were mixed and dispersed in a round stainless steel flask using a homogenizer "Ultra Turrax (registered trademark) T50" (manufactured by IKA Corporation), and then heated to 55 °C while stirring the inside of the flask in an oil bath for heating. After holding at 55 °C for 30 minutes, it was confirmed that aggregated particles with a median diameter (D50) of 4.8 μm based on volume were generated in the solution. When the temperature of the oil bath for heating was further raised and held at 56 °C for 2 hours, the median diameter (D50) based on volume became 5.9 μm. Thereafter, 1 mol / L sodium hydroxide was added to the system to adjust the pH of the system to 5.0, and then the stainless steel flask was sealed using a magnetic seal and heated to 98 °C while continuing stirring. By continuing stirring for 6 hours, the fusion (bonding) between the binder resin particles was completed, and toner base particle dispersion liquid 1 was prepared. The median diameter (D50) based on volume of the toner base particles in the dispersion liquid was 6.0 μm.

[0117] <Washing and Drying Process> Toner base particle dispersion liquid 1 was subjected to solid-liquid separation using a basket type centrifuge "MARKIII Model Number 60×40" (manufactured by Matsumoto Machinery Sales Co., Ltd.) to form a wet cake of toner base particles. The wet cake was washed with ion-exchanged water at 45 °C using the above-mentioned basket centrifuge until the electrical conductivity of the filtrate reached 5 μS / cm, and then transferred to a "Flash Jet Dryer" (manufactured by Seishin Enterprise Co., Ltd.) and dried until the moisture content reached 0.5% by mass to obtain toner base particles.

[0118] <External additive treatment of toner base particles> To 100 parts by mass of the toner base particles obtained above, 1 part by mass of hydrophobic silica (number average primary particle diameter = 12 nm) and 0.3 part by mass of hydrophobic titania (number average primary particle diameter = 20 nm) were added and mixed using a Henschel mixer (registered trademark) to perform an external additive treatment, thereby producing Toner 1.

[0119] [Production of Toners 2 to 22] Toners 2 to 22 were produced in the same manner as the production of Toner 1, except that each binder resin particle dispersion was prepared with the monomer combinations and addition amounts shown in Table I below, each release agent particle dispersion was prepared using the release agents described in Table I below, and toner base particles were prepared using the binder resin particle dispersion and the release agent particle dispersion so as to have the contents described in Table I below.

[0120] Note that the volume-based median diameter of the binder resin particles in each binder resin particle dispersion prepared with the monomer combinations and addition amounts shown in Table I below was 125 nm in all cases. Furthermore, the volume-based median diameter of the release agent particles in each release agent particle dispersion prepared using the release agents described in Table I below was as follows: · Pentaerythritol tetrabehenate: 490 nm · Stearyl stearate: 460 nm · Methyl lignocerate: 430 nm · Hexadecyl palmitate: 450 nm · Methyl triacontanoate: 450 nm · Paraffin (paraffin wax, HNP-51, manufactured by Nippon Seiro Co., Ltd.): 600 nm

[0121] The composition of each toner is shown in Table I below. In Table I below, St represents styrene, MMA represents methyl methacrylate, nBA represents n-butyl acrylate, iBA represents iso-butyl acrylate, 2EHA represents 2-ethylhexyl acrylate, MAA represents methacrylic acid, and AA represents acrylic acid. Note that the addition amount of the itaconic acid derivative (the first polymerizable monomer) and the addition amount of the second polymerizable monomer in Table I represent the respective addition amounts when the total addition amount of the itaconic acid derivative and the second monomer is 100% by mass. Also, the addition amount of the release agent represents the addition amount of the release agent when the addition amount of the polymer composed of the itaconic acid derivative and the second monomer is 100% by mass.

[0122] [Preparation of Two-Component Developer] 100 parts by mass of ferrite particles (volume-based median diameter: 50 μm, manufactured by Powdertech Co., Ltd.) and 4 parts by mass of a methyl methacrylate-cyclohexyl methacrylate copolymer resin (volume-based median diameter of primary particles: 85 nm) were placed in a horizontal stirring blade type high-speed stirring device and mixed for 15 minutes under the conditions of a peripheral speed of the stirring blade: 8 m / s and a temperature: 30°C. Then, the temperature was raised to 120°C and stirring was continued for 4 hours. Thereafter, it was cooled, and fragments of the methyl methacrylate-cyclohexyl methacrylate copolymer resin were removed using a 200-mesh sieve to produce a resin-coated carrier. This resin-coated carrier was mixed with each of the above toners 1 to 22 so that the toner concentration was 7% by mass based on the total mass of the toner and the carrier, and two-component developers 1 to 22 were prepared.

[0123]

Table 1

[0124] [Evaluation] The two-component developers 1 to 22 were used to evaluate the following evaluation items (1) and (2), and the evaluation results are shown in Table II below.

[0125] (1) Hot Offset Resistance As an image forming apparatus, a commercially available multifunction printer "bizhub PRO (registered trademark) C6500" (manufactured by Konica Minolta, Inc.) was used, and the above-mentioned two-component developer was installed as a developer in this apparatus. The surface temperature of the fixing heating member in the fixing means of the heat roll fixing method was set to 175°C, and in an environment of normal temperature and normal humidity (temperature 20°C, relative humidity 50%RH), a thick paper with a basis weight of 350 g / m 2 was used to form an image, and a solid image with 5 g / m 3 of toner fixed was obtained as a visible image. After forming the solid image, the amount of toner offset on the roller was visually determined by passing the plain thick paper with a basis weight of 350 g / m 2 that had not been imaged through the fuser again. If it is rank 3 or higher, it is considered qualified. (Evaluation Criteria) Rank 5: No offset at all Rank 4: Slight offset occurs partially Rank 3: Slight offset occurs Rank 2: Clear offset occurs partially Rank 1: Clear offset occurs over the entire surface

[0126] (2) Roller contamination resistance As an image forming apparatus, a commercially available multifunction printer "bizhub PRO C6500" (manufactured by Konica Minolta Business Technologies, Inc.) was used, and the above-mentioned two-component developer was installed as a developer in this apparatus. As a visible image, 1000 prints of a solid image with an image density of 0.8 were performed. Then, the degree of contamination of the transport roller in the multifunction printer that came into contact with the image surface was visually observed, and a four-level evaluation was conducted. (Evaluation Criteria) Rank 4: No contamination on the transport roller Rank 3: Slight contamination can be seen on the transport roller partially Rank 2: Slight contamination can be seen on the transport roller over the entire surface Rank 1: Clear contamination can be seen on the transport roller

[0127] [Table 2]

[0128] As is clear from the results shown in Table II above, it was found that Toners 1 to 20 of the present invention containing a polymer having a structural unit represented by the general formula (1) and using a fatty acid ester wax as a release agent exhibited excellent performance in both hot offset resistance and roller contamination resistance. On the other hand, it was found that Toner 21 using paraffin wax instead of the fatty acid ester wax and Toner 22 using a resin not containing a polymer having a structural unit represented by the general formula (1) could not satisfy both hot offset resistance and roller contamination resistance.

Claims

1. An electrostatic charge image developing toner containing toner base particles containing a binder resin and a release agent, wherein the binder resin contains a polymer having a structural unit represented by the following general formula (1), the polymer having the structural unit represented by the general formula (1) is a copolymer of a first polymerizable monomer having a structure represented by the following general formula (2) and a second polymerizable monomer copolymerizable with the first polymerizable monomer, the release agent contains a fatty acid ester, and the fatty acid ester is at least one of behenyl behenate and pentaerythritol tetrabehenate. An electrostatic charge image developing toner characterized by the above. 【Chemical Formula 1】 [In the general formula (1), R １ and R ２ each independently represents any one of a methyl group, an n-propyl group, an iso-butyl group, and a 2-ethylhexyl group.] [Chemical 2] In general formula (2), R １ and R ２ each independently represents any one of a methyl group, an n-propyl group, an iso-butyl group, and a 2-ethylhexyl group.]

2. The content of the structural unit derived from the first polymerizable monomer is in the range of 5 to 40% by mass with respect to 100% by mass of the polymer having the structural unit represented by the general formula (1). The electrostatic charge image developing toner according to Claim 1, characterized by the above.

3. The electrostatic charge image developing toner according to Claim 1 or Claim 2, characterized in that the second polymerizable monomer is selected from at least styrenes and the group consisting of acrylic acid esters and methacrylic acid esters.

4. The electrostatic charge image developing toner according to Claim 3, characterized in that the second polymerizable monomer is selected from one or more of styrene, acrylic acid, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, methacrylic acid, and methyl methacrylate.

5. The content of the release agent is in the range of 5 to 20% by mass with respect to 100% by mass of the polymer having the structural unit represented by the general formula (1). The electrostatic charge image developing toner according to any one of Claims 1 to 4, characterized by the above.

6. A method for manufacturing an electrostatic charge image developing toner according to any one of Claims 1 to 5, characterized by having a step of polymerizing a first polymerizable monomer having a structure represented by the general formula (2) to synthesize a polymer having a structural unit represented by the general formula (1) and preparing a binder resin particle dispersion liquid. A method for manufacturing an electrostatic charge image developing toner.

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