Toner for developing electrostatic images

Abstract

Provided is a toner for development of electrostatic images that comprises color resin particles containing a binder resin, a color agent, a charge control agent, and a mold release agent, wherein the storage modulus G'(60) of the color resin particles at 60°C, obtained by a dynamic viscoelasticity measurement, is 1.0×108 to 5.0×108 Pa, the storage modulus G'(100) at 100°C is 8.0×104 to 2.3×105 Pa, and the storage modulus G'(150) at 150°C is 1.4×104 to 3.0×104 Pa.

Description

[Technical Field]

[0001] The present invention relates to a toner for developing electrostatic images, which is used to develop electrostatic latent images in electrophotography, electrostatic recording, electrostatic printing, and the like. [Background technology]

[0002] BACKGROUND ART Image forming apparatuses such as electrophotographic apparatuses, electrostatic recording apparatuses, and electrostatic printing apparatuses widely use a method of forming a desired image by developing an electrostatic latent image formed on a photosensitive member with a toner for developing an electrostatic image, and this method is applied to copiers, printers, facsimiles, and combination machines thereof.

[0003] For example, in an electrophotographic device using electrophotography, the surface of a photosensitive member made of a photoconductive material is generally uniformly charged by various means, an electrostatic latent image is then formed on the photosensitive member, the electrostatic latent image is then developed using toner (developing step), and if necessary, the toner image is transferred to a recording material such as paper (transfer step), and then the toner is fixed to the recording material by applying heat while applying pressure with a fixing roll and a fixing film (fixing step), thereby obtaining a printed matter.

[0004] Among the image forming processes, the fixing process typically requires heating the fixing roll or fixing film to a temperature of 150° C. or higher during fixing, consuming a large amount of electricity as an energy source. In response to this, in recent years, with increasing demands for reduced energy consumption and faster printing for the image forming apparatuses, there has been a demand for the design of toners that can maintain a high fixing rate even at low fixing temperatures (toners with excellent low-temperature fixing properties).

[0005] In response to the above demands, various methods have been proposed, including a method of lowering the glass transition temperature (Tg) of the toner, a method of incorporating a low-melting-point resin and / or a low-molecular-weight resin into the toner, and a method of incorporating a low-softening-point substance (releasing agent) having releasability (separability) such as wax into the toner.

[0006] However, while improving low-temperature fixability allows the temperature of the fixing roll or fixing film to be set lower during fixing, when the toner is used at high temperatures or when the toner is left (stored) for a long period of time, fusion (blocking (aggregation)) between toner particles may occur more easily, which may result in a decrease in the shelf life of the toner. For this reason, when designing toner, it is necessary to take into consideration shelf life, which is a property that is contradictory to low-temperature fixability, and there is a demand for the development of toners that can improve low-temperature fixability without impairing shelf life and reduce power consumption.

[0007] For example, Patent Document 1 discloses a toner having toner particles containing a binder resin and a colorant, and the toner has a storage modulus (G'60) at a temperature of 60°C of 1.0 x 10 in viscoelastic properties measured at a frequency of 6.28 rad / sec using a rotating plate rheometer. 7 ~1.0×10 9 (Pa), and the maximum storage modulus (G'p) exists between 110°C and 140°C, and G'p is 5.0×10 4 ~5.0×10 6 (Pa). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-177914 Summary of the Invention [Problem to be solved by the invention]

[0009] On the other hand, the technology of Patent Document 1 uses a polyester resin as a binder resin, and the technology of Patent Document 1 has a problem in that low-temperature fixability is insufficient. Furthermore, improving the low-temperature fixability of a toner can sometimes cause a problem of filming on the fixation film during the fixation process (when the fixation process of fixing the toner to the recording material by applying heat while applying pressure with a fixation roll and fixation film is repeatedly performed, the molten toner adheres to the fixation film, the fixation film is coated with toner, the release properties of the fixation film are reduced, and offset resistance is reduced). Therefore, a toner is required that has good low-temperature fixability while also appropriately resolving this filming problem.

[0010] An object of the present invention is to provide a toner for developing electrostatic images which is excellent in storage stability, low-temperature fixability, and filming resistance to fixing film. [Means for solving the problem]

[0011] The present inventors have conducted studies to achieve the above object, and have found that the above problem can be solved by controlling the storage modulus G'(60) at 60°C, the storage modulus G'(100) at 100°C, and the storage modulus G'(150) at 150°C of the colored resin particles, which are measured by dynamic viscoelasticity measurement, within specific ranges in a toner for developing electrostatic images containing colored resin particles including a binder resin, a colorant, a charge control agent, and a release agent, and have thus completed the present invention.

[0012] That is, according to the present invention, there is provided a toner for developing electrostatic images, which contains colored resin particles including a binder resin, a colorant, a charge control agent, and a release agent, and The storage modulus G'(60) of the colored resin particles at 60°C measured by dynamic viscoelasticity measurement is 1.0 x 10 8 ~5.0×10 8 Pa, and the storage modulus at 100°C, G'(100), is 8.0 × 10 4 ~2.3×10 5 Pa, and the storage modulus at 150°C, G'(150), is 1.4 × 10 4 ~3.0×10 4A toner for developing electrostatic images is provided, the toner having a Pa.

[0013] In the toner for developing electrostatic images of the present invention, the colored resin particles preferably have a melting temperature (T1 / 2) of 150 to 220°C by the 1 / 2 method. In the electrostatic image developing toner of the present invention, it is preferable that the colored resin particles further contain an additive having a polydiene structure whose solubility in styrene at a temperature of 40°C is 3 to 40 g / 100 g. In the toner for developing electrostatic images of the present invention, the additive having a polydiene structure is preferably a conjugated diene-aromatic vinyl thermoplastic elastomer. In the toner for developing electrostatic images of the present invention, the additive having a polydiene structure is preferably a block copolymer containing at least one aromatic vinyl polymer block and at least one conjugated diene polymer block. In the toner for developing electrostatic images of the present invention, the release agent is preferably a fatty acid ester compound having a number average molecular weight (Mn) of 500 to 1,500. In the toner for developing electrostatic images of the present invention, it is preferable that the ratio G'(100) / G'(150) of the storage modulus G'(100) at 100°C to the storage modulus G'(150) at 150°C of the colored resin particles is 3.0 to 15.0. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a toner for developing electrostatic images that is excellent in storage stability, low-temperature fixability, and filming resistance to fixing films. DETAILED DESCRIPTION OF THE INVENTION

[0015] The toner for developing electrostatic images of the present invention (hereinafter, sometimes simply referred to as "toner") is a toner for developing electrostatic images containing colored resin particles including a binder resin, a colorant, a charge control agent, and a release agent, The storage modulus G'(60) of the colored resin particles at 60°C measured by dynamic viscoelasticity measurement is 1.0 x 108 ~5.0×10 8 Pa, and the storage modulus at 100°C, G'(100), is 8.0 × 10 4 ~2.3×10 5 Pa, and the storage modulus at 150°C, G'(150), is 1.4 × 10 4 ~3.0×10 4 It is what is Pa.

[0016] First, a method for producing colored resin particles constituting the toner of the present invention will be described.

[0017] The methods for producing the colored resin particles constituting the toner of the present invention are roughly divided into dry methods such as pulverization methods and wet methods such as emulsion polymerization aggregation methods, dispersion polymerization methods, suspension polymerization methods, and solution suspension methods, and the wet methods are preferred because they are more likely to produce toners with excellent printing properties such as image reproducibility. Among the wet methods, polymerization methods such as emulsion polymerization aggregation methods, dispersion polymerization methods, and suspension polymerization methods are preferred because they are more likely to produce toners with a relatively small particle size distribution on the order of microns, and of these, suspension polymerization is more preferred.

[0018] The emulsion polymerization aggregation method is a method of producing colored resin particles by polymerizing an emulsified polymerizable monomer to obtain resin fine particles, and aggregating the resin fine particles with a colorant, etc. The solution suspension method is a method of producing colored resin particles by dropping a solution in which toner components such as a binder resin and a colorant are dissolved or dispersed in an organic solvent into an aqueous medium to form droplets, and then removing the organic solvent, and either of these methods can be used.

[0019] The colored resin particles constituting the toner of the present invention can be produced by either a wet method or a dry method, but when the colored resin particles are produced by adopting (A) suspension polymerization, which is preferred among wet methods, or (B) pulverization, which is typical among dry methods, the process is as follows: First, (A) suspension polymerization will be described.

[0020] (A) Suspension polymerization method (A-1) Preparation of polymerizable monomer composition In the suspension polymerization method, first, a polymerizable monomer, a colorant, a charge control agent, a release agent, an additive having a polydiene structure, which is used as needed, and other additives, which are used as needed, are mixed and dissolved to prepare a polymerizable monomer composition. The mixing for preparing the polymerizable monomer composition is carried out, for example, using a media-type disperser.

[0021] In the present invention, a polymerizable monomer refers to a polymerizable compound, which becomes a binder resin through polymerization. It is preferable to use a monovinyl monomer as the main component of the polymerizable monomer. Examples of monovinyl monomers include styrene-based monomers such as styrene, vinyltoluene, α-methylstyrene, and ethylstyrene; (meth)acrylate-based monomers such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, dimethylaminoethyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, and dimethylaminoethyl methacrylate; acrylic acid and methacrylic acid; nitrile compounds such as acrylonitrile and methacrylonitrile; amide compounds such as acrylamide and methacrylamide; and olefins such as ethylene, propylene, and butylene. These monovinyl monomers can be used alone or in combination of two or more. Among these, styrene-based monomers and (meth)acrylate-based monomers are preferred, and styrene and butyl acrylate are more preferred. Furthermore, it is preferred to use at least a styrene-based monomer and a (meth)acrylate-based monomer as the monovinyl monomer, since this can further improve the low-temperature fixability of the resulting toner.

[0022] The content of styrene-based monomer units in the binder resin used in the present invention (content of all monovinyl monomer units) is preferably 73 to 76% by mass, more preferably 73 to 75% by mass, and even more preferably 73.5 to 74.5% by mass. By setting the content of styrene-based monomer units within this range, the resulting toner can be made to have a well-balanced and excellent storage stability and filming resistance against fixing films. Furthermore, the content of (meth)acrylate-based monomer units (content of all monovinyl monomer units) is preferably 24 to 27% by mass, more preferably 25 to 27% by mass, and even more preferably 25.5 to 26.5% by mass. By setting the content of (meth)acrylate-based monomer units within this range, the resulting toner can be made to have excellent storage stability and improved low-temperature fixability.

[0023] In the present invention, to further improve storage stability, it is preferable to use any crosslinkable polymerizable monomer (crosslinking agent) together with the monovinyl monomer. A crosslinkable polymerizable monomer refers to a monomer having two or more polymerizable functional groups. Examples of crosslinkable polymerizable monomers include aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene, and derivatives thereof; ester compounds in which two or more carboxylic acids are ester-bonded to an alcohol having two or more hydroxyl groups, such as ethylene glycol dimethacrylate and diethylene glycol dimethacrylate; other divinyl compounds such as N,N-divinylaniline and divinyl ether; and compounds having three or more vinyl groups. These crosslinkable polymerizable monomers can be used alone or in combination of two or more. The amount of the crosslinkable polymerizable monomer used is preferably 0.40 to 0.85 parts by mass, more preferably 0.42 to 0.80 parts by mass, and even more preferably 0.45 to 0.80 parts by mass per 100 parts by mass of the monovinyl monomer. By setting the amount and content of the crosslinkable polymerizable monomer within the above range, the storage stability, low-temperature fixability, and filming resistance to the fixing film of the resulting toner can be further improved.

[0024] Furthermore, a macromonomer can be used as part of the polymerizable monomer. The use of any macromonomer can further improve the storage stability and low-temperature fixability of the resulting toner. A macromonomer is a reactive oligomer or polymer having a polymerizable carbon-carbon unsaturated bond at the end of its molecular chain, and typically having a number-average molecular weight (Mn) of 1,000 to 30,000. A macromonomer that provides a polymer with a higher Tg (glass transition temperature) than the Tg of a polymer obtained without polymerizing the macromonomer is preferred. The amount of macromonomer used is preferably 0.03 to 5 parts by mass, more preferably 0.05 to 1 part by mass, per 100 parts by mass of the monovinyl monomer.

[0025] In the present invention, colorants are used, and when producing color toners (usually, four types of toners are used: black toner, cyan toner, yellow toner, and magenta toner), black colorants, cyan colorants, yellow colorants, and magenta colorants can be used, respectively.

[0026] As the black colorant, for example, pigments and dyes such as carbon black, titanium black, and magnetic powders such as iron zinc oxide and iron nickel oxide can be used.

[0027] Examples of cyan colorants include copper phthalocyanine pigments, their derivatives, and anthraquinone pigments and dyes, etc. Specific examples include CI Pigment Blue 2, 3, 6, 15, 15:1, 15:2, 15:3, 15:4, 16, 17:1, 60, etc.

[0028] Examples of yellow colorants that can be used include azo pigments such as monoazo pigments and disazo pigments, condensed polycyclic pigments, and dyes. Specific examples include CI Pigment Yellow 3, 12, 13, 14, 15, 17, 62, 65, 73, 74, 83, 93, 97, 120, 138, 151, 155, 180, 181, 185, 186, 214, and 219, and CI Solvent Yellow 98 and 162.

[0029] Examples of magenta colorants that can be used include azo pigments such as monoazo pigments and disazo pigments, condensed polycyclic pigments, and dyes. Specific examples include CI Pigment Red 31, 48, 57:1, 58, 60, 63, 64, 68, 81, 83, 87, 88, 89, 90, 112, 114, 122, 123, 144, 146, 149, 150, 163, 170, 184, 185, 187, 202, 206, 207, 209, 251, CI Solvent Violet 31, 47, 59, and CI Pigment Violet 19.

[0030] In the present invention, each colorant may be used alone or in combination of two or more kinds, and the amount of colorant used is preferably 1 to 10 parts by mass relative to 100 parts by mass of binder resin (100 parts by mass of polymerizable monomer for obtaining binder resin).

[0031] The charge control agent is not particularly limited as long as it is one that is generally used as a charge control agent for toner. However, among charge control agents, positively or negatively charged charge control resins are preferred from the viewpoint of having high compatibility with polymerizable monomers and being able to impart stable chargeability (charge stability) to toner particles, thereby improving the dispersibility of colorants. Furthermore, from the viewpoint of obtaining a positively charged toner, positively charged charge control resins are more preferably used.

[0032] Examples of positively chargeable charge control agents include nigrosine dyes, quaternary ammonium salts, triaminotriphenylmethane compounds, and imidazole compounds, as well as polyamine resins, quaternary ammonium group-containing copolymers, and quaternary ammonium base-containing copolymers, which are preferably used as charge control resins.

[0033] Examples of negatively chargeable charge control agents include azo dyes containing metals such as Cr, Co, Al, and Fe, metal salicylate compounds, and metal alkylsalicylate compounds, as well as sulfonic acid group-containing copolymers, sulfonate salt group-containing copolymers, carboxylic acid group-containing copolymers, and carboxylic acid salt group-containing copolymers, which are preferably used as charge control resins.

[0034] The weight average molecular weight (Mw) of the charge control resin is in the range of 5,000 to 30,000, preferably 8,000 to 25,000, and more preferably 10,000 to 20,000, in terms of polystyrene, measured by gel permeation chromatography (GPC) using tetrahydrofuran.

[0035] Furthermore, the copolymerization ratio of the monomer having a functional group such as a quaternary ammonium group or a sulfonate group in the charge control resin is preferably in the range of 0.5 to 12 mass%, more preferably in the range of 1.0 to 6 mass%, and even more preferably in the range of 1.5 to 3 mass%.

[0036] The content of the charge control agent is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 8 parts by mass, relative to 100 parts by mass of the binder resin (100 parts by mass of the polymerizable monomer for obtaining the binder resin). By setting the amount of the charge control agent added within the above range, it is possible to appropriately increase the dispersibility of the colorant while effectively suppressing the occurrence of fog and print smears.

[0037] The release agent can be any release agent that is generally used as a toner release agent without any particular limitation, but from the viewpoint of appropriately improving the low-temperature fixability and hot offset resistance of the resulting toner, it is preferable for it to have a number-average molecular weight (Mn) of 500 to 1500, and it is preferably a fatty acid ester compound having a number-average molecular weight (Mn) of 500 to 1500. The term "fatty acid ester compound" refers to a product obtained by an ester reaction between a monohydric alcohol and / or a polyhydric alcohol and a saturated fatty acid and / or an unsaturated fatty acid.

[0038] Specific examples of monohydric alcohols include saturated monohydric aliphatic alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 1-pentanol, 1-hexanol, octanol, 2-ethyl-1-hexanol, nonyl alcohol, lauryl alcohol, cetyl alcohol, stearyl alcohol, and behenyl alcohol; unsaturated monohydric aliphatic alcohols such as allyl alcohol, methallyl alcohol, crotyl alcohol, and oleyl alcohol; monohydric alicyclic alcohols such as cyclohexanol; and monohydric aromatic alcohols such as phenol, phenylmethanol (benzyl alcohol), methylphenol (cresol), p-ethylphenol, dimethylphenol (xylenol), nonylphenol, dodecylphenol, phenylphenol, and naphthol.

[0039] Specific examples of polyhydric alcohols include dihydric saturated aliphatic alcohols such as ethylene glycol and propylene glycol; dihydric aromatic alcohols such as catechol and hydroquinone; and trihydric or higher saturated aliphatic alcohols such as glycerin, pentaerythritol, dipentaerythritol, and polyglycerin.

[0040] Among these monohydric alcohols and polyhydric alcohols, monohydric to tetrahydric saturated aliphatic alcohols are preferred, stearyl alcohol, behenyl alcohol and pentaerythritol are more preferred, stearyl alcohol and behenyl alcohol are more preferred, and behenyl alcohol is particularly preferred.

[0041] The fatty acids used as raw materials for the fatty acid ester compounds are preferably saturated fatty acids and / or unsaturated fatty acids having a carbon number of 12 to 22, more preferably 14 to 18. Among these, saturated fatty acids having the above carbon numbers are particularly preferred because they make it easier to obtain fatty acid ester compounds having a number average molecular weight (Mn) of 500 to 1500.

[0042] Specific examples of saturated fatty acids having the above carbon numbers include, but are not limited to, lauric acid (12 carbon atoms), myristic acid (14 carbon atoms), pentadecylic acid (15 carbon atoms), palmitic acid (16 carbon atoms), margaric acid (17 carbon atoms), stearic acid (18 carbon atoms), arachidic acid (20 carbon atoms), and behenic acid (22 carbon atoms). Among these saturated fatty acids, stearic acid (18 carbon atoms), arachidic acid (20 carbon atoms), and behenic acid (22 carbon atoms) are preferred, with stearic acid (18 carbon atoms) being more preferred.

[0043] Specific examples of unsaturated fatty acids include, but are not limited to, the following compounds: Palmitoleic acid (CH3(CH2)5CH=CH(CH2)7COOH) Oleic acid (CH3(CH2)7CH=CH(CH2)7COOH) Vaccenic acid (CH3(CH2)5CH=CH(CH2)9COOH) Linoleic acid (CH3(CH2)3(CH2CH=CH)2(CH2)7COOH) (9,12,15)-linolenic acid (CH3(CH2CH=CH)3(CH2)7COOH) (6,9,12)-Linolenic acid (CH3(CH2)3(CH2CH=CH)3(CH2)4COOH) Eleostearic acid (CH3(CH2)3(CH=CH)3(CH2)7COOH) Arachidonic acid (CH3(CH2)3(CH2CH=CH)4(CH2)3COOH)

[0044] The saturated fatty acids and / or unsaturated fatty acids may be used alone or in combination of two or more. Among the saturated fatty acids and unsaturated fatty acids, saturated fatty acids are preferred, with stearic acid, arachidic acid, and behenic acid being more preferred, stearic acid and behenic acid being even more preferred, and behenic acid being particularly preferred.

[0045] The fatty acid ester compounds described above can be produced by conventional methods. Examples of methods for producing such fatty acid ester compounds include a method of carrying out an esterification reaction using a monohydric alcohol and / or a polyhydric alcohol with a saturated fatty acid and / or an unsaturated fatty acid. Furthermore, commercially available fatty acid ester compounds can also be used as the fatty acid ester compounds, and examples of commercially available fatty acid ester compounds include "WEP2," "WEP3," "WEP4," "WEP5," "WE6," and "WE11" (all trade names) manufactured by NOF Corporation.

[0046] In the present invention, instead of or together with the fatty acid ester compound, a release agent other than a fatty acid ester compound may be used as the release agent, and examples thereof include low-molecular-weight polyolefin waxes and modified waxes thereof, natural plant waxes such as jojoba, petroleum waxes such as paraffin, mineral waxes such as ozokerite, synthetic waxes such as Fischer-Tropsch wax, and polyhydric alcohol esters such as dipentaerythritol esters. These may be used alone or in combination of two or more.

[0047] The number average molecular weight (Mn) of the release agent is preferably 500 to 1500, more preferably 550 to 1200, and even more preferably 550 to 1100. The number average molecular weight (Mn) of the release agent can be measured, for example, as a polystyrene-equivalent value measured by gel permeation chromatography (GPC) using tetrahydrofuran.

[0048] The content of the release agent is preferably 1 to 30 parts by mass, more preferably 10 to 25 parts by mass, and even more preferably 15 to 25 parts by mass, relative to 100 parts by mass of the binder resin (100 parts by mass of the polymerizable monomer for obtaining the binder resin). By setting the content of the release agent within the above range, it is possible to further improve the low-temperature fixability while making the particle size distribution of the obtained toner relatively uniform.

[0049] In the present invention, it is preferable that the colored resin particles further contain an additive having a polydiene structure, which has a solubility in styrene of 3 to 40 g / 100 g at a temperature of 40° C. By including such an additive having a polydiene structure, the storage stability and low-temperature fixability of the resulting toner can be further improved.

[0050] The additive having a polydiene structure used in the present invention is not particularly limited as long as it has a polydiene structure (i.e., a structure derived from a diene compound) and has a solubility in styrene of 3 to 40 g / 100 g at a temperature of 40° C. The solubility of the additive having a polydiene structure in styrene at a temperature of 40° C. is preferably 5 to 30 g / 100 g, more preferably 10 to 25 g / 100 g.

[0051] The additive having an additive with a polydiene structure used in the present invention is not particularly limited, and examples thereof include conjugated diene-aromatic vinyl thermoplastic elastomers, which are polymers having structural units derived from a conjugated diene compound and structural units derived from an aromatic vinyl compound; conjugated diene elastomers such as polybutadiene rubber and polyisoprene rubber; and the like. Conjugated diene-aromatic vinyl thermoplastic elastomers are preferred, and among conjugated diene-aromatic vinyl thermoplastic elastomers, unhydrogenated conjugated diene-aromatic vinyl thermoplastic elastomers are particularly preferred.

[0052] The conjugated diene-aromatic vinyl thermoplastic elastomer used in the present invention includes random, block, graft and other copolymers of a conjugated diene monomer, an aromatic vinyl monomer and, if necessary, other monomers copolymerizable therewith, as well as hydrogenated products of such copolymers.

[0053] Such a conjugated diene-aromatic vinyl thermoplastic elastomer is not particularly limited, but from the viewpoint of further improving the storage stability and low-temperature fixability of the toner, a block copolymer containing at least one aromatic vinyl polymer block and at least one conjugated diene polymer block can be preferably used.

[0054] Hereinafter, a block copolymer containing at least one aromatic vinyl polymer block and at least one conjugated diene polymer block (hereinafter, sometimes simply referred to as "block copolymer"), which is a representative example of a conjugated diene-aromatic vinyl thermoplastic elastomer, will be described. The block copolymer used in the present invention contains at least one aromatic vinyl polymer block obtained by polymerizing an aromatic vinyl monomer and at least one conjugated diene polymer block obtained by polymerizing a conjugated diene monomer.

[0055] The aromatic vinyl monomer is not particularly limited as long as it is an aromatic vinyl compound, but examples thereof include styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 2,4-diisopropylstyrene, 2,4-dimethylstyrene, 4-t-butylstyrene, 5-t-butyl-2-methylstyrene, 2-chlorostyrene, 3-chlorostyrene, 4-chlorostyrene, 4-bromostyrene, 2-methyl-4,6-dichlorostyrene, 2,4-dibromostyrene, and vinylnaphthalene. Among these, styrene is preferred. These aromatic vinyl monomers can be used alone or in combination of two or more in each aromatic vinyl polymer block. Furthermore, when a block copolymer has multiple aromatic vinyl polymer blocks, each aromatic vinyl polymer block may be composed of the same aromatic vinyl monomer unit or different aromatic vinyl monomer units.

[0056] The aromatic vinyl polymer block may contain other monomer units as long as aromatic vinyl monomer units are the main repeating units. Examples of other monomers that can be used in the aromatic vinyl polymer block include conjugated diene monomers such as 1,3-butadiene and isoprene (2-methyl-1,3-butadiene), α,β-unsaturated nitrile monomers, unsaturated carboxylic acid or acid anhydride monomers, unsaturated carboxylic acid ester monomers, and non-conjugated diene monomers. The content of monomer units other than aromatic vinyl monomer units in the aromatic vinyl polymer block is preferably 20% by mass or less, more preferably 10% by mass or less, and particularly preferably substantially 0% by mass.

[0057] The conjugated diene monomer is not particularly limited as long as it is a conjugated diene compound, but examples thereof include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene, 1,3-pentadiene, and 1,3-hexadiene. Among these, 1,3-butadiene and / or isoprene are preferred, with isoprene being particularly preferred, from the viewpoint of achieving high improvements in storage stability, low-temperature fixability, and hot offset resistance. These conjugated diene monomers can be used alone or in combination of two or more in each conjugated diene polymer block. Furthermore, when a block copolymer has multiple conjugated diene polymer blocks, each conjugated diene polymer block may be composed of the same conjugated diene monomer units or different conjugated diene monomer units. Furthermore, a hydrogenation reaction may be performed on some of the unsaturated bonds in each conjugated diene polymer block.

[0058] The conjugated diene polymer block may contain other monomer units as long as the conjugated diene monomer units are the main repeating units. Examples of other monomers that can be used in the conjugated diene polymer block include aromatic vinyl monomers such as styrene and α-methylstyrene, α,β-unsaturated nitrile monomers, unsaturated carboxylic acid monomers, unsaturated carboxylic anhydride monomers, unsaturated carboxylic ester monomers, and non-conjugated diene monomers. The content of monomer units other than conjugated diene monomer units in the conjugated diene polymer block is preferably 20% by mass or less, more preferably 10% by mass or less, and particularly preferably substantially 0% by mass.

[0059] The vinyl bond content of the conjugated diene polymer block (the proportion of 1,2-vinyl bond units and 3,4-vinyl bond units in all conjugated diene monomer units in the conjugated diene polymer block) is not particularly limited, but is preferably 1 to 20 mol%, more preferably 2 to 15 mol%, and particularly preferably 3 to 10 mol%.

[0060] The block copolymer is not particularly limited in the number of each polymer block or the bonding form thereof, as long as it contains at least one aromatic vinyl polymer block and one conjugated diene polymer block. Specific examples of the block copolymer used in the present invention include the following. In the following specific examples, Ar represents an aromatic vinyl polymer block, D represents a conjugated diene polymer block, X represents a residue of a coupling agent, and n represents an integer of 2 or greater. (a) Aromatic vinyl-conjugated diene block copolymer represented as Ar-D (b) Aromatic vinyl-conjugated diene-aromatic vinyl block copolymers represented as Ar-D-Ar and / or (Ar-D)nX (c) Conjugated diene-aromatic vinyl-conjugated diene block copolymers represented as D-Ar-D and / or (D-Ar)nX (d) aromatic vinyl-conjugated diene-aromatic vinyl-conjugated diene block copolymer represented as Ar-D-Ar-D; (e) A block copolymer composition comprising any combination of two or more of the above (a) to (d).

[0061] In the present invention, the block copolymer preferably contains at least the aromatic vinyl-conjugated diene block copolymer (a) represented by Ar-D, and more preferably contains at least the aromatic vinyl-conjugated diene block copolymer (a) represented by Ar-D and the aromatic vinyl-conjugated diene-aromatic vinyl block copolymer (b) represented by Ar-D-Ar and / or (Ar-D)nX. The content of the aromatic vinyl-conjugated diene block copolymer (Ar-D) in the conjugated diene-aromatic vinyl thermoplastic elastomer used in the present invention is preferably 40% by weight or more, more preferably 50% by weight or more, and more preferably 55% by weight or more. The upper limit is not particularly limited, but is preferably 98% by weight or less, and more preferably 95% by weight or less.

[0062] In the aromatic vinyl-conjugated diene block copolymer represented by Ar-D, the weight average molecular weight (Mw(Ar)) of the aromatic vinyl polymer block Ar is not particularly limited, but is preferably 10,000 to 50,000, more preferably 15,000 to 30,000, and the weight average molecular weight (Mw(D)) of the conjugated diene polymer block D is not particularly limited, but is preferably 50,000 to 200,000, more preferably 60,000 to 150,000.

[0063] In the aromatic vinyl-conjugated diene-aromatic vinyl block copolymer represented by Ar-D-Ar and / or (Ar-D)nX, the weight-average molecular weight (Mw(Ar)) of the aromatic vinyl polymer block Ar is not particularly limited, but is preferably 10,000 to 30,000, more preferably 15,000 to 25,000, and the weight-average molecular weight (Mw(D)) of the conjugated diene polymer block D is not particularly limited, but is preferably 100,000 to 300,000, more preferably 120,000 to 250,000. The weight average molecular weights are all polystyrene-equivalent values ​​measured by gel permeation chromatography (GPC) using tetrahydrofuran.

[0064] In the block copolymer used in the present invention, the content of aromatic vinyl monomer units relative to all monomer units is preferably 10 to 30% by mass, more preferably 12 to 25% by mass, and even more preferably 15 to 25% by mass. By setting the content of aromatic vinyl monomer units within the above range, it is possible to achieve a high level of balance between the affinity of the block copolymer for the release agent and the affinity of the block copolymer for the binder resin, and the resulting toner can have excellent storage stability, low-temperature fixability, and hot offset resistance.

[0065] In the case where all polymer components constituting the block copolymer are composed only of aromatic vinyl monomer units and conjugated diene monomer units, the content of aromatic vinyl monomer units in the block copolymer can be easily measured by ozonolysis of the block copolymer followed by reduction with lithium aluminum hydride according to the method described in Rubber Chem. Technol., 45, 1295 (1972). This decomposes the conjugated diene monomer unit portions, allowing only the aromatic vinyl monomer unit portions to be isolated.

[0066] The weight-average molecular weight (Mw) of the aromatic vinyl polymer block in the block copolymer is not particularly limited, but is preferably 10,000 to 50,000, more preferably 20,000 to 40,000, in terms of polystyrene, measured by gel permeation chromatography (GPC) using tetrahydrofuran. The weight-average molecular weight (Mw) of the conjugated diene polymer block in the block copolymer is not particularly limited, but is preferably 50,000 to 200,000, more preferably 60,000 to 180,000.

[0067] The melt index (MI) of the block copolymer is not particularly limited, but is selected, for example, from the range of 1 to 1000 g / 10 min, and preferably from 5 to 30 g / 10 min, as a value measured in accordance with ASTM D-1238 (G conditions, 200°C, 5 kg).

[0068] The block copolymer used in the present invention can be produced by a conventional method, for example, by anionic living polymerization, in which an aromatic vinyl monomer and a conjugated diene monomer are sequentially polymerized to form polymer blocks, and then, if necessary, a coupling agent is added to the polymer blocks to couple them.

[0069] Furthermore, when the block copolymer used in the present invention contains at least the above-mentioned (a) aromatic vinyl-conjugated diene block copolymer represented by Ar-D and (b) aromatic vinyl-conjugated diene-aromatic vinyl block copolymer represented by Ar-D-Ar and / or (Ar-D)nX, the following method can be employed.

[0070] Specifically, an aromatic vinyl monomer is first polymerized by anionic living polymerization, followed by the addition and polymerization of a conjugated diene monomer to obtain a diblock copolymer with an active end. Next, a coupling agent less than 1 molar equivalent is added to the active end of the diblock copolymer to couple a portion of the diblock copolymer with an active end to obtain an aromatic vinyl-conjugated diene-aromatic vinyl block copolymer represented by (Ar-D)nX. A polymerization terminator is then added to deactivate the remaining diblock copolymer with an active end to obtain a diblock copolymer represented by Ar-D. In this case, a bifunctional coupling agent such as dichlorosilane, monomethyldichlorosilane, dimethyldichlorosilane, diphenyldimethoxysilane, diphenyldiethoxysilane, dichloroethane, dibromoethane, methylene chloride, or dibromomethane can be used as the coupling agent to obtain an aromatic vinyl-conjugated diene-aromatic vinyl block copolymer represented by Ar-D-Ar (where D includes a residue of the coupling agent).

[0071] In the present invention, the content ratios of the aromatic vinyl-conjugated diene block copolymer (a) represented by Ar-D and the aromatic vinyl-conjugated diene-aromatic vinyl block copolymer (b) represented by Ar-D-Ar and / or (Ar-D)nX are not particularly limited, but the content ratio of the aromatic vinyl-conjugated diene block copolymer (a) represented by Ar-D is preferably 10 to 90 mass%, more preferably 20 to 80 mass%. Also, the content ratio of the aromatic vinyl-conjugated diene-aromatic vinyl block copolymer (b) represented by Ar-D-Ar and / or (Ar-D)nX is preferably 10 to 90 mass%, more preferably 20 to 80 mass%.

[0072] Furthermore, instead of the block copolymers described above, random copolymers of aromatic vinyl monomers and conjugated diene monomers can also be used as conjugated diene-based thermoplastic elastomers. Random copolymers of aromatic vinyl monomers and conjugated diene monomers can be produced, for example, by living anionic polymerization using an organic alkali metal compound as a polymerization initiator. Examples of organic alkali metal compounds include organolithium compounds, organosodium compounds, and organopotassium compounds. Specific examples include organomonolithium compounds such as n-butyllithium, sec-butyllithium, t-butyllithium, hexyllithium, phenyllithium, and stilbenelithium; organic polyvalent lithium compounds such as dilithiomethane, 1,4-dilithiobutane, 1,4-dilithio-2-ethylcyclohexane, 1,3,5-trilithiobenzene, and 1,3,5-tris(lithiomethyl)benzene; organosodium compounds such as sodium naphthalene; and organopotassium compounds such as potassium naphthalene. Among these organometallic compounds, n-butyllithium is preferred.

[0073] In the random copolymer of an aromatic vinyl monomer and a conjugated diene monomer used in the present invention, the content of aromatic vinyl monomer units relative to all monomer units is preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less. By setting the content of aromatic vinyl monomer units within the above range, it is possible to achieve a high level of balance between the affinity of the random copolymer for the release agent and the affinity of the block copolymer for the binder resin, and the resulting toner can have excellent storage stability and low-temperature fixability.

[0074] Furthermore, in the present invention, conjugated diene elastomers such as polybutadiene rubber and polyisoprene rubber can also be suitably used as additives having a polydiene structure. Conjugated diene elastomers such as polybutadiene rubber and polyisoprene rubber can be produced, for example, by living anionic polymerization using an organic alkali metal compound as a polymerization initiator. Examples of the organic alkali metal compound that can be used include those described above.

[0075] The weight-average molecular weight (Mw) of the additive having a polydiene structure used in the present invention is not particularly limited, but is preferably 60,000 to 350,000, more preferably 80,000 to 250,000, in terms of polystyrene, measured by gel permeation chromatography (GPC) using tetrahydrofuran. By setting the weight-average molecular weight (Mw) within the above range, the storage stability, low-temperature fixability, and hot offset resistance of the resulting toner can be further improved.

[0076] The content of the additive having a polydiene structure is preferably 1 to 10 parts by mass, more preferably 1 to 9 parts by mass, even more preferably 2 to 7 parts by mass, and particularly preferably 2 to 5 parts by mass, relative to 100 parts by mass of the binder resin (100 parts by mass of the polymerizable monomer for obtaining the binder resin). By setting the content of the additive having a polydiene structure within the above range, the effect of adding it, i.e., the effect of improving the storage stability and low-temperature fixability of the resulting toner, can be further enhanced.

[0077] In the present invention, an acrylic resin may be used as another additive to further suppress bleeding out of the release agent. The acrylic resin is a copolymer (acrylate copolymer) whose main components are at least one of an acrylic acid ester and a methacrylic acid ester and at least one of an acrylic acid and a methacrylic acid. The acid monomer is preferably acrylic acid.

[0078] Examples of acrylic resins include copolymers of acrylic acid esters and acrylic acid, copolymers of acrylic acid esters and methacrylic acid, copolymers of methacrylic acid esters and acrylic acid, copolymers of methacrylic acid esters and methacrylic acid, copolymers of acrylic acid esters, methacrylic acid esters and acrylic acid, copolymers of acrylic acid esters, methacrylic acid esters and methacrylic acid, and copolymers of acrylic acid esters, methacrylic acid esters, acrylic acid and methacrylic acid. Of these, it is preferable to use a copolymer of acrylic acid esters, methacrylic acid esters and acrylic acid.

[0079] The acid value of the acrylic resin is usually 0.5 to 7 mgKOH / g, preferably 1 to 6 mgKOH / g, and more preferably 1.5 to 4 mgKOH / g. By setting the acid value of the acrylic resin within the above range, it is possible to satisfactorily prepare the desired colored resin particles, while also achieving good heat-resistant storage stability, low-temperature fixability, and print durability under temperature and humidity environments ranging from low-temperature, low-humidity environments to high-temperature, high-humidity environments. The acid value of the acrylic resin is a value measured in accordance with JIS K0070, a standard method for analyzing fats and oils established by the Japanese Industrial Standards Committee (JICS).

[0080] The weight average molecular weight (Mw) of the acrylic resin is usually 6,000 to 50,000, preferably 8,000 to 25,000, and more preferably 10,000 to 20,000. When the weight average molecular weight (Mw) of the acrylic resin is within the above range, it is possible to provide good heat-resistant storage stability, durability, and low-temperature fixability.

[0081] The glass transition temperature Tg of the acrylic resin is usually 60 to 85° C., preferably 65 to 80° C., and more preferably 70 to 77° C. When the glass transition temperature is within the above range, good heat-resistant storage stability and low-temperature fixability can be achieved. The glass transition temperature Tg of the acrylic resin can be determined, for example, in accordance with ASTM D3418-82.

[0082] The ratio of the acrylic acid ester monomer units, the methacrylic acid ester monomer units, the acrylic acid monomer units, and the methacrylic acid monomer units in the acrylic resin is not particularly limited as long as the above-mentioned acid value, weight average molecular weight Mw, and glass transition temperature are satisfied.

[0083] The ratio of the four types of monomer units can be adjusted by the mass ratio of the acrylic acid ester, methacrylic acid ester, acrylic acid, and methacrylic acid added during copolymer synthesis. The mass ratio of the added amounts may be, for example, (acrylic acid ester and / or methacrylic acid ester):(acrylic acid and / or methacrylic acid)=(99-99.95):(0.05-1), preferably (acrylic acid ester and / or methacrylic acid ester):(acrylic acid and / or methacrylic acid)=(99.4-99.9):(0.1-0.6), and more preferably (acrylic acid ester and / or methacrylic acid ester):(acrylic acid and / or methacrylic acid)=(99.5-99.7):(0.3-0.5). Among these polymerizable monomers, the acrylic acid esters and / or methacrylic acid esters may be substituted with other monomers such as styrene derivatives, nitrile compounds, and amide compounds exemplified as the monovinyl monomers constituting the binder resin, within the range that does not impair the effects of the present invention. The proportion of such other monomers is 10% by mass or less, preferably 2% by mass or less, of the total amount of the acrylic acid esters and / or methacrylic acid esters added, and it is preferable that they are not substituted.

[0084] Examples of acrylic acid esters used in acrylic resins include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, n-pentyl acrylate, sec-pentyl acrylate, isopentyl acrylate, neopentyl acrylate, n-hexyl acrylate, isohexyl acrylate, neohexyl acrylate, sec-hexyl acrylate, and tert-hexyl acrylate. Of these, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, and n-butyl acrylate are preferred, and n-butyl acrylate is more preferred.

[0085] Examples of methacrylic acid esters used in acrylic resins include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, n-pentyl methacrylate, sec-pentyl methacrylate, isopentyl methacrylate, neopentyl methacrylate, n-hexyl methacrylate, isohexyl methacrylate, neohexyl methacrylate, sec-hexyl methacrylate, and tert-hexyl methacrylate. Of these, methyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, and n-butyl methacrylate are preferred, and methyl methacrylate is more preferred.

[0086] The amount of the acrylic resin added is preferably 0.3 to 4 parts by mass, more preferably 0.5 to 3.0 parts by mass, and even more preferably 0.7 to 2.0 parts by mass, relative to 100 parts by mass of the binder resin (100 parts by mass of the polymerizable monomer for obtaining the binder resin). By setting the amount of the acrylic resin added within the above range, it is possible to ensure good environmental stability and sufficient effects of its addition.

[0087] Although commercially available acrylic resins can be used, they can also be produced by known methods such as solution polymerization, aqueous solution polymerization, ionic polymerization, high-temperature high-pressure polymerization, and suspension polymerization.

[0088] Furthermore, a molecular weight modifier may be used as another additive. The molecular weight modifier is not particularly limited as long as it is a molecular weight modifier generally used for toners. Examples include mercaptans such as t-dodecyl mercaptan, n-dodecyl mercaptan, n-octyl mercaptan, and 2,2,4,6,6-pentamethylheptane-4-thiol; and thiuram disulfides such as tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, N,N'-dimethyl-N,N'-diphenylthiuram disulfide, and N,N'-dioctadecyl-N,N'-diisopropylthiuram disulfide. These molecular weight modifiers may be used alone or in combination of two or more. The amount of the molecular weight modifier used is preferably 5 parts by mass or less, more preferably 0.5 to 4 parts by mass, and even more preferably 0.5 to 3 parts by mass, relative to 100 parts by mass of the binder resin (100 parts by mass of the polymerizable monomer for obtaining the binder resin).

[0089] (A-2) Suspension step for obtaining a suspension (droplet formation step) Next, the polymerizable monomer composition obtained in the above (A-1) polymerizable monomer composition preparation step, which contains the polymerizable monomer, colorant, charge control agent, and release agent, as well as any optional additives having a polydiene structure, is dispersed in an aqueous dispersion medium, and a polymerization initiator is added, followed by droplet formation of the polymerizable monomer composition. Here, "suspension" refers to forming droplets of the polymerizable monomer composition in the aqueous dispersion medium. The dispersion process for droplet formation can be carried out using a device capable of strong stirring, such as an in-line emulsifier / disperser (manufactured by Pacific Machinery Works, trade name: Milder) or a high-speed emulsifier / disperser (manufactured by Primix Corporation, trade name: TK Homomixer MARK II).

[0090] Examples of polymerization initiators include persulfates such as potassium persulfate and ammonium persulfate; azo compounds such as 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2-methyl-N-(2-hydroxyethyl)propionamide), 2,2'-azobis(2-amidinopropane) dihydrochloride, 2,2'-azobis(2,4-dimethylvaleronitrile), and 2,2'-azobisisobutyronitrile; and organic peroxides such as di-t-butyl peroxide, benzoyl peroxide, t-butylperoxy-2-ethylhexanoate, t-hexylperoxy-2-ethylbutanoate, diisopropyl peroxydicarbonate, di-t-butylperoxyisophthalate, and t-butylperoxyisobutyrate. These can be used alone or in combination of two or more. Among these, organic peroxides are preferred because they can reduce the amount of residual polymerizable monomers and provide excellent print durability. Among organic peroxides, peroxyesters are preferred because they have good initiator efficiency and can reduce the amount of residual polymerizable monomers, and non-aromatic peroxyesters, i.e., peroxyesters without an aromatic ring, are more preferred.

[0091] As described above, the polymerization initiator may be added after the polymerizable monomer composition is dispersed in an aqueous medium and before droplets are formed, or may be added to the polymerizable monomer composition before it is dispersed in an aqueous medium (a medium containing water as a main component).

[0092] The amount of the polymerization initiator used for polymerizing the polymerizable monomer composition is preferably 0.1 to 20 parts by mass, more preferably 0.3 to 15 parts by mass, even more preferably 3 to 5 parts by mass, and particularly preferably 3 to 4 parts by mass, relative to 100 parts by mass of the binder resin (100 parts by mass of the polymerizable monomer for obtaining the binder resin).

[0093] In the present invention, it is preferable to add a dispersion stabilizer to the aqueous medium. Examples of the dispersion stabilizer include inorganic compounds such as sulfates (e.g., barium sulfate, calcium sulfate, etc.); carbonates (e.g., barium carbonate, calcium carbonate, magnesium carbonate, etc.); phosphates (e.g., calcium phosphate, etc.); metal oxides (e.g., aluminum oxide, titanium oxide, etc.); metal hydroxides (e.g., aluminum hydroxide, magnesium hydroxide, ferric hydroxide, etc.); and organic compounds such as water-soluble polymers (e.g., polyvinyl alcohol, methyl cellulose, gelatin, etc.); anionic surfactants; nonionic surfactants; and amphoteric surfactants. The above dispersion stabilizers can be used alone or in combination of two or more. The amount of the dispersion stabilizer added is preferably 0.1 to 20 parts by mass, more preferably 0.2 to 10 parts by mass, per 100 parts by mass of the binder resin (100 parts by mass of the polymerizable monomer for obtaining the binder resin).

[0094] Among the dispersion stabilizers, inorganic compounds, particularly colloidal metal hydroxides with poor water solubility, are preferred. By using inorganic compounds, particularly colloidal metal hydroxides with poor water solubility, the particle size distribution of the colored resin particles can be narrowed and the amount of dispersion stabilizer remaining after washing can be reduced, thereby enabling the toner to reproduce images more clearly without deteriorating environmental stability.

[0095] (A-3) Polymerization process The desired suspension (aqueous dispersion medium containing droplets of the polymerizable monomer composition) obtained in the (A-2) step of obtaining a suspension (droplet forming step) is heated to initiate polymerization, thereby obtaining an aqueous dispersion of colored resin particles containing a binder resin, a colorant, a charge control agent, a release agent, and an additive having a polydiene structure, which is used as needed.

[0096] The polymerization temperature in the present invention is preferably 50° C. or higher, more preferably 60 to 95° C. The polymerization time in the present invention is preferably 1 to 20 hours, more preferably 2 to 15 hours.

[0097] From the viewpoint of carrying out polymerization in a state in which droplets of the polymerizable monomer composition are stably dispersed, the polymerization reaction may be allowed to proceed while carrying out a dispersion treatment by stirring following the step of obtaining the suspension (droplet formation step) (A-2) above.

[0098] In the present invention, the colored resin particles thus obtained may be used as a toner by adding an external additive as they are, or may be so-called core-shell type (also called "capsule type") colored resin particles obtained by forming a core layer around the colored resin particles obtained by the polymerization step, which is different from the core layer. By coating the core layer made of a material with a low softening point with a material with a higher softening point, the storage stability and low-temperature fixability of the resulting toner can be further improved.

[0099] The method for producing the core-shell type colored resin particles is not particularly limited and can be any conventionally known method, but in situ polymerization and phase separation methods are preferred from the viewpoint of production efficiency.

[0100] A method for producing core-shell type colored resin particles by in situ polymerization will be described below. In the in situ polymerization method, a polymerizable monomer for forming a shell layer (polymerizable monomer for shell) and a polymerization initiator for the shell are added to an aqueous dispersion medium in which colored resin particles are dispersed, and polymerization is carried out to obtain core-shell type colored resin particles.

[0101] As the polymerizable monomer for the shell, the same polymerizable monomers as those described above can be used. Among them, it is preferable to use a monomer that can give a polymer with a Tg exceeding 80°C, such as styrene or methyl methacrylate, either alone or in combination of two or more.

[0102] Examples of the shell polymerization initiator used in the polymerization of the shell polymerizable monomer include metal persulfates such as potassium persulfate and ammonium persulfate; and water-soluble azo compounds such as 2,2'-azobis(2-methyl-N-(2-hydroxyethyl)propionamide) and 2,2'-azobis(2-methyl-N-(1,1-bis(hydroxymethyl)2-hydroxyethyl)propionamide). The amount of the shell polymerization initiator used is preferably 0.1 to 30 parts by mass, and more preferably 1 to 20 parts by mass, per 100 parts by mass of the shell polymerizable monomer.

[0103] The polymerization temperature for the shell layer is preferably 50° C. or higher, more preferably 60 to 95° C. The polymerization time for the shell layer is preferably 1 to 20 hours, more preferably 2 to 15 hours.

[0104] (A-4) Washing, filtering, dehydration, and drying steps After the polymerization is completed, the aqueous dispersion of colored resin particles obtained in the polymerization step (A-3) is preferably subjected to a series of operations of washing, filtering, dehydration, and drying according to a conventional method, and if necessary, repeated several times.

[0105] First, in order to remove the dispersion stabilizer remaining in the aqueous dispersion of the colored resin particles, it is preferable to add an acid or an alkali to the aqueous dispersion of the colored resin particles and wash it. When the dispersion stabilizer used is an inorganic compound soluble in acid, it is preferable to add an acid to the aqueous dispersion of the colored resin particles and wash it. On the other hand, when the dispersion stabilizer used is an inorganic compound soluble in alkali, it is preferable to add an alkali to the aqueous dispersion of the colored resin particles and wash it.

[0106] Furthermore, when an acid-soluble inorganic compound is used as the dispersion stabilizer, it is preferable to add an acid to the aqueous dispersion of colored resin particles to adjust the pH to preferably 6.5 or less, more preferably 6 or less. The acid to be added may be an inorganic acid such as sulfuric acid, hydrochloric acid, or nitric acid, or an organic acid such as formic acid or acetic acid, but sulfuric acid is particularly preferred because it has a high efficiency in removing the dispersion stabilizer and places a small burden on the production equipment.

[0107] The dehydration and filtration methods can be any known method, and are not particularly limited. Examples include centrifugal filtration, vacuum filtration, pressure filtration, etc. The drying method is also not particularly limited, and various methods can be used.

[0108] (B) Crushing method When the colored resin particles are produced by the pulverization method, the process is as follows. First, the binder resin, colorant, charge control agent, release agent, and additive having a polydiene structure, as well as other additives added as needed, are mixed using a mixer such as a ball mill, V-type mixer, Henschel mixer (trade name), high-speed dissolver, internal mixer, or Fohlberg mixer. Next, the mixture obtained above is kneaded while heating using a pressure kneader, twin-screw extrusion mixer, roller, or the like. The kneaded product obtained is coarsely pulverized using a pulverizer such as a hammer mill, cutter mill, or roller mill. The resulting mixture is then finely pulverized using a pulverizer such as a jet mill or high-speed rotary pulverizer, and then classified to the desired particle size using a classifier such as an air classifier or airflow classifier, thereby obtaining colored resin particles by pulverization.

[0109] The binder resin, colorant, charge control agent, release agent, and additive having a polydiene structure used in the pulverization method, as well as other additives added as needed, can be the same as those listed for the suspension polymerization method (A).The colored resin particles obtained by the pulverization method can also be made into core-shell type colored resin particles by a method such as in situ polymerization, similar to the colored resin particles obtained by the suspension polymerization method (A).

[0110] In addition to the binder resins described above, resins that have been widely used in toners can also be used as the binder resin.Specific examples of binder resins used in the pulverization method include polystyrene, styrene-butyl acrylate copolymers, polyester resins, and epoxy resins.

[0111] (Colored resin particles) The colored resin particles can be obtained by the above-mentioned (A) suspension polymerization method or (B) pulverization method. The colored resin particles constituting the toner will be described below, and the colored resin particles described below include both core-shell type and non-core-shell type particles.

[0112] The colored resin particles used in the present invention have a storage modulus G'(60) at 60°C, a storage modulus G'(100) at 100°C, and a storage modulus G'(150) at 150°C, which are determined by dynamic viscoelasticity measurement, controlled to fall within specific ranges. That is, the colored resin particles used in the present invention have a storage modulus G'(60) at 60°C, which is determined by dynamic viscoelasticity measurement, of 1.0 x 10 8 ~5.0×10 8 Pa range, the storage modulus G'(100) at 100°C is 8.0 × 10 4 ~2.3×10 5 The storage modulus G'(150) at 150°C is 1.4×10 4 ~3.0×10 4 According to the present invention, by controlling the storage modulus G' of the colored resin particles at 60°C, 100°C and 150°C within the above range, the toner obtained can be excellent in storage stability, low-temperature fixability and filming resistance to the fixing film.

[0113] The storage modulus G'(60) of the colored resin particles at 60°C, determined by dynamic viscoelasticity measurement, is 1.0 x 10 8 ~5.0×10 8Pa range, but preferably 1.1 × 10 8 ~2.9×10 8 Pa range, more preferably 1.3×10 8 ~2.8×10 8 If the storage modulus G'(60) at 60°C is too small, the storage stability will decrease, whereas if it is too large, the low-temperature fixability will deteriorate.

[0114] The storage modulus G'(100) of the colored resin particles at 100°C, determined by dynamic viscoelasticity measurement, is 8.0 x 10 4 ~2.3×10 5 Pa range, but preferably 1.1 × 10 5 ~2.2×10 5 Pa range, more preferably 1.2 × 10 5 ~2.2×10 5 If the storage modulus G'(100) at 100°C is too small, the storage stability will be deteriorated, whereas if it is too large, the low-temperature fixability will be reduced.

[0115] The storage modulus G'(150) of the colored resin particles at 150°C, determined by dynamic viscoelasticity measurement, is 1.4 x 10 4 ~3.0×10 4 Pa range, but preferably 1.4 × 10 4 ~2.5×10 4 Pa range, more preferably 1.4×10 4 ~2.2×10 4 If the storage modulus G'(150) at 150°C is too small, the toner will have poor filming resistance to the fixing film, whereas if it is too large, the low-temperature fixing property will be deteriorated.

[0116] The ratio G'(60) / G'(100) of the storage modulus G'(60) at 60°C to the storage modulus G'(100) at 100°C of the colored resin particles, determined by dynamic viscoelasticity measurement, is not particularly limited, but is preferably 5.0 × 10 from the viewpoint of making the resulting toner superior in storage stability, low-temperature fixability, and filming resistance to the fixing film. 2 ~1.5×10 3 It is preferable that the concentration is controlled within the range of 6.0 × 10 2 ~1.4×10 3 It is more preferable that the concentration is controlled within the range of 7.5 × 10 2 ~1.3×10 3 It is more preferable that the temperature is controlled within the range of .

[0117] Furthermore, the ratio G'(100) / G'(150), of the storage modulus G'(100) at 100°C to the storage modulus G'(150) at 150°C of the colored resin particles, determined by dynamic viscoelasticity measurement, is not particularly limited, but from the viewpoint of making the resulting toner superior in storage stability, low-temperature fixability, and filming resistance to fixing film, it is preferably controlled to a range of 3.0 to 15.0, more preferably 4.0 to 13.5, and even more preferably 5.0 to 11.0.

[0118] The method for measuring the storage modulus G'(60) at 60°C, the storage modulus G'(100) at 100°C, and the storage modulus G'(150) at 150°C of colored resin particles is not particularly limited, but the colored resin particles can be sandwiched between a pair of 8 mmφ plates with a load of 20 g (the colored resin particles are uniformly distributed over an area of ​​8 mmφ and sandwiched between the pair of plates with a load of 20 g) as a measurement sample, and dynamic viscoelasticity measurement can be performed over the range of 45 to 150°C using a dynamic viscoelasticity measuring device with a rotational plane rheometer at a measurement frequency of 24 Hz and a heating rate of 5°C / min.

[0119] In the present invention, the method for adjusting the storage modulus G'(60) at 60°C, the storage modulus G'(100) at 100°C, and the storage modulus G'(150) at 150°C of the colored resin particles to fall within the above-mentioned ranges is not particularly limited, and examples thereof include a method for adjusting the content of monomer units derived from monovinyl monomers (for example, the content of styrene-based monomer units) in the binder resin used in the present invention to fall within the above-mentioned ranges, a method for adjusting the amount of a crosslinkable polymerizable monomer (crosslinking agent) used in obtaining the binder resin used in the present invention to fall within the above-mentioned ranges, a method for adjusting the amount of a release agent to fall within the above-mentioned ranges, a method for adjusting the amount of a polymerization initiator and an amount of a molecular weight modifier used in polymerizing a polymerizable monomer composition to fall within the above-mentioned ranges, and a method for adding an additive having a polydiene structure to the colored resin particles and adjusting the amount of the additive to fall within the above-mentioned ranges, and these methods can be combined as appropriate.

[0120] The melting temperature (T1 / 2) of the colored resin particles in the 1 / 2 method is preferably 150 to 220°C, more preferably 152 to 210°C, and even more preferably 155 to 200°C, from the viewpoint of further improving the storage stability, low-temperature fixability, and filming resistance of the fixing film obtained. The melting temperature (T1 / 2) of the colored resin particles in the 1 / 2 method is measured using a flow tester at a measurement starting temperature of 40°C, a temperature rise rate of 3°C / min, a preheating time of 5 minutes, and a cylinder pressure of 10 kgf / cm. 2 The measurement can be performed under the conditions of a die diameter of 0.5 mm and a die length of 1.0 mm.

[0121] From the viewpoint of image reproducibility, the volume average particle diameter Dv of the colored resin particles is preferably 3 to 15 μm, more preferably 4 to 12 μm, and even more preferably 5 to 8 μm. If the volume average particle diameter Dv of the colored resin particles is below the above range, the fluidity of the toner may decrease, and deterioration of image quality due to fogging or the like may easily occur. On the other hand, if the volume average particle diameter Dv of the colored resin particles exceeds the above range, the resolution of the obtained image may decrease.

[0122] Furthermore, the particle size distribution (Dv / Dn), which is the ratio of the volume average particle size (Dv) to the number average particle size (Dn) of the colored resin particles, is preferably 1.00 to 1.30, more preferably 1.00 to 1.20, from the viewpoint of image reproducibility. If the particle size distribution (Dv / Dn) of the colored resin particles exceeds the above range, the fluidity of the toner may decrease, and image quality may be easily deteriorated due to fogging or the like. The volume average particle size Dv and number average particle size Dn of the colored resin particles can be measured, for example, using a particle size analyzer (manufactured by Beckman Coulter, trade name: Multisizer).

[0123] Furthermore, from the viewpoint of image reproducibility, the average circularity of the colored resin particles is preferably from 0.960 to 1.000, more preferably from 0.970 to 1.000, and even more preferably from 0.980 to 1.000.

[0124] The above-mentioned colored resin particles may be used as a toner as they are or by mixing the colored resin particles with carrier particles (ferrite, iron powder, etc.). However, in order to adjust the chargeability, fluidity, storage stability, etc. of the toner, an external additive may be added and mixed with the colored resin particles using a high-speed mixer (for example, FM Mixer (trade name, manufactured by Nippon Coke & Engineering Co., Ltd.)) to form a one-component toner, or the colored resin particles, external additives, and carrier particles may be mixed to form a two-component toner.

[0125] The agitator used for the external addition treatment is not particularly limited as long as it is an agitator that can adhere an external additive to the surface of the colored resin particles. For example, the external addition treatment can be performed using an agitator that is capable of mixing and stirring, such as FM Mixer (trade name, manufactured by Nippon Coke and Engineering Co., Ltd.), Super Mixer (trade name, manufactured by Kawada Manufacturing Co., Ltd.), Q Mixer (trade name, manufactured by Nippon Coke and Engineering Co., Ltd.), Mechanofusion System (trade name, manufactured by Hosokawa Micron Corporation), or Mechano Mill (trade name, manufactured by Okada Seiko Co., Ltd.).

[0126] Examples of external additives include inorganic fine particles made of silica, titanium oxide, aluminum oxide, zinc oxide, tin oxide, calcium carbonate, calcium phosphate, cerium oxide, etc.; and organic fine particles made of polymethyl methacrylate resin, silicone resin, melamine resin, etc. Among these, inorganic fine particles are preferred, silica and titanium oxide are more preferred, and silica is particularly preferred. It is also preferred to use two or more types of fine particles in combination as external additives. These external additives can be used alone, but it is preferred to use two or more types in combination.

[0127] The external additive is preferably used in an amount of 0.3 to 6 parts by mass, more preferably 1.2 to 3 parts by mass, relative to 100 parts by mass of the colored resin particles.

[0128] The toner of the present invention contains, as colored resin particles, a binder resin, a colorant, a charge control agent, and a release agent, and the storage modulus G'(60) of the colored resin particles at 60°C as determined by dynamic viscoelasticity measurement is 1.0 x 10 8 ~5.0×10 8 Pa, and the storage modulus at 100°C, G'(100), is 8.0 × 10 4 ~2.3×10 5 Pa, and the storage modulus at 150°C, G'(150), is 1.4 × 10 4 ~3.0×10 4 The toner of the present invention has excellent storage stability, low-temperature fixability, and filming resistance to fixing film, and therefore can fully meet the recent demands for reduced energy consumption and faster printing. [Example]

[0129] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. Note that "parts" and "%" are by mass unless otherwise specified. The test methods used in the present examples and comparative examples are as follows.

[0130] (1) Weight average molecular weight of conjugated diene-aromatic vinyl thermoplastic elastomer The molecular weight was determined as a polystyrene equivalent by high-performance liquid chromatography (HPLC) using tetrahydrofuran as a carrier at a flow rate of 0.35 ml / min. The instrument used was a Tosoh HLC8220, and the column consisted of three connected Shodex® KF-404HQ columns (Showa Denko K.K., Shodex®) at 40°C. The detectors were a differential refractometer and an ultraviolet detector. The molecular weight was calibrated using 12 standard polystyrenes (5 to 3 million) from Polymer Laboratory.

[0131] (2) Content of each block copolymer in the conjugated diene-aromatic vinyl thermoplastic elastomer The ratio was determined from the area ratio of the peaks corresponding to each block copolymer in the chart obtained by the above high performance liquid chromatography.

[0132] (3) Weight average molecular weight of the styrene polymer block of the block copolymer that constitutes the conjugated diene-aromatic vinyl thermoplastic elastomer Following the method described in Rubber Chem. Technol., 45, 1295 (1972), the isoprene polymer block of the block copolymer was decomposed by reacting the block copolymer with ozone and reducing it with lithium aluminum hydride. Specifically, the procedure was as follows: 300 mg of sample was dissolved in a reaction vessel containing 100 ml of dichloromethane treated with molecular sieves. The reaction vessel was then placed in a cooling bath and cooled to -25°C. Ozone generated by an ozone generator was then introduced into the reaction vessel while oxygen was flowing into the vessel at a flow rate of 170 ml / min. Thirty minutes after the start of the reaction, completion of the reaction was confirmed by introducing the gas flowing out of the reaction vessel into an aqueous potassium iodide solution. Next, 50 ml of diethyl ether and 470 mg of lithium aluminum hydride were placed in a separate reaction vessel purged with nitrogen. The ozone-reacted solution was slowly added dropwise to the reaction vessel while the reaction vessel was cooled with ice water. The reaction vessel was then placed in a water bath, gradually heated, and refluxed at 40°C for 30 minutes. Dilute hydrochloric acid was then added dropwise to the reaction vessel while stirring the solution, and the addition was continued until hydrogen generation was almost completely eliminated. After the reaction, the solid product formed in the solution was filtered and extracted with 100 ml of diethyl ether for 10 minutes. This extract was combined with the filtrate obtained by filtration, and the solvent was distilled off to obtain a solid sample. The weight-average molecular weight of the sample thus obtained was measured according to the above-mentioned method for measuring weight-average molecular weight, and the value was taken as the weight-average molecular weight of the styrene polymer block.

[0133] (4) Weight average molecular weight of the isoprene polymer block of the block copolymer that constitutes the conjugated diene-aromatic vinyl thermoplastic elastomer The weight average molecular weight of the corresponding styrene polymer block was subtracted from the weight average molecular weight of the block copolymer obtained as described above, and the weight average molecular weight of the isoprene polymer block was calculated based on the calculated value.

[0134] (5) Styrene unit content of the block copolymer constituting the conjugated diene-aromatic vinyl thermoplastic elastomer The styrene content was determined based on the ratio of the detected intensities measured by the differential refractometer and the ultraviolet detector in the high performance liquid chromatography. Copolymers having different styrene unit contents were prepared in advance, and a calibration curve was prepared using these copolymers.

[0135] (6) Vinyl bond content of the isoprene polymer block of the block copolymer constituting the conjugated diene-aromatic vinyl thermoplastic elastomer It was determined based on proton NMR measurements.

[0136] (7) Styrene unit content of conjugated diene-aromatic vinyl thermoplastic elastomer It was determined based on proton NMR measurements.

[0137] (8) Melt index of conjugated diene-aromatic vinyl thermoplastic elastomer Measurement was performed in accordance with ASTM D1238 (G condition, 200°C, 5 kg load).

[0138] (9) Melting temperature of colored resin particles (T1 / 2) The melting temperature (T1 / 2) of the colored resin particles by the 1 / 2 method was calculated from the melt viscosity measured using a flow tester. Specifically, the melt viscosity was measured using a flow tester (Shimadzu Corporation, product name: CFT-500C) under the conditions of a predetermined starting temperature, heating rate, preheating time, and shear stress. The melting temperature (T1 / 2) by the 1 / 2 method was then calculated from the obtained melt viscosity. Measurement start temperature: 40°C, temperature rise rate: 3°C / min, preheating time: 5 min, cylinder pressure: 10 kgf / cm 2 , Die diameter: 0.5mm, Die length: 1.0mm

[0139] (10) Storage modulus G'(60) at 60°C, storage modulus G'(100) at 100°C, storage modulus G'(150) at 150°C of colored resin particles The colored resin particles were sandwiched between a pair of 8 mm diameter plates (parallel plates or crosshatch plates) with a load of 20 g (the colored resin particles were uniformly distributed over an area of ​​8 mm diameter and sandwiched between the pair of plates with a load of 20 g) and used as the measurement sample. Dynamic viscoelasticity measurements were performed using a dynamic viscoelasticity measuring device (product name "ARES-G2", manufactured by TA Instruments) with a rotational plane rheometer under conditions of a measurement frequency of 24 Hz, a load of 20 g, and a heating rate of 5°C / min over the range of 45 to 150°C to determine the elasticity.

[0140] (11) Evaluation of toner storage stability 10 g of toner was placed in a 100 mL polyethylene container and sealed. The container was then submerged in a thermostatic water bath set at a predetermined temperature and removed after 8 hours. The toner was transferred from the container onto a 42-mesh sieve while minimizing vibration and placed in a powder measuring instrument (manufactured by Hosokawa Micron Corporation, product name: Powder Tester PT-R). The sieve amplitude was set to 1.0 mm, and the sieve was vibrated for 30 seconds. The mass of the toner remaining on the sieve was measured and used as the mass of the aggregated toner. The maximum temperature (°C) at which the mass of the aggregated toner became 0.5 g or less was determined as the storage stability temperature and used as an index of storage stability.

[0141] (12) Minimum fixing temperature of toner A fixation test was conducted using a commercially available non-magnetic single-component development printer (print speed 20 ppm) modified to allow for variable temperature adjustment of the fuser roll. The fixation test involved printing a solid black image (100% print density) and varying the temperature of the modified printer's fuser roll in 5°C increments. The toner fixation rate at each temperature was measured, and the temperature-fixation rate relationship was determined. Tape was peeled off from the printed area of ​​the solid black image (100% print density), and the fixation rate was calculated from the ratio of image density before and after tape peeling. In other words, if the image density before tape peeling is ID (before) and the image density after tape peeling is ID (after), the fixation rate can be calculated using the following formula: Retention rate (%) = (ID (later) / ID (earlier)) x 100 Here, the tape peeling operation refers to a series of operations in which adhesive tape (manufactured by Sumitomo 3M, trade name: Scotch Mending Tape 810-3-18) is applied to the measurement portion of the test paper, pressed with a constant pressure to adhere it, and then peeled off the adhesive tape at a constant speed in the direction along the paper. In addition, the image density was measured using a reflective image densitometer (manufactured by Macbeth, trade name: RD914). In this fixing test, the lowest fixing roll temperature at which the fixing rate exceeded 80% was determined as the minimum fixing temperature of the toner.

[0142] (13) Toner filming test on fixing film A commercially available non-magnetic, single-component printer with a film-fixing system (resolution 600 dpi, print speed 28 pages per minute) was loaded with print paper and toner in the developing device. After leaving the printer for 24 hours in a low-temperature, low-humidity, normal-humidity (L / L) environment (10°C temperature, 20% RH), 10,000 sheets were continuously printed at 4% print density in the same environment. Every 500 sheets, a solid print (100% print density) was performed, and the prints were visually inspected for print defects such as black spots (areas with excessive toner coverage) or white areas (areas where the toner had peeled off). The toner's resistance to filming on the fixing film was evaluated according to the following criteria. ○: No printing defects such as black spots or white spots were observed in continuous printing of 10,000 sheets. ×: At least one of the printing defects, black spots or white spots, was observed during continuous printing of 10,000 sheets.

[0143] [Manufacturing Example 1] A pressure-resistant reactor was charged with 23.2 kg of cyclohexane, 1.5 mmol of N,N,N',N'-tetramethylethylenediamine (TMEDA), and 1.70 kg of styrene. While stirring at 40°C, 99.1 mmol of n-butyllithium was added, and polymerization was carried out for 1 hour while the temperature was raised to 50°C. The polymerization conversion of styrene was 100% by weight. Subsequently, 6.03 kg of isoprene was continuously added to the reactor over 1 hour while maintaining the temperature at 50-60°C. After the addition of isoprene was completed, polymerization was continued for another 1 hour to form styrene-isoprene diblock copolymer B (copolymer B represented by Ar-D). The polymerization conversion of isoprene was 100%. Next, 15.0 mmol of dimethyldichlorosilane was added as a coupling agent, and a coupling reaction was carried out for 2 hours to form a styrene-isoprene-styrene triblock copolymer (copolymer A represented by Ar-D-Ar). Subsequently, 198 mmol of methanol was added as a polymerization terminator and mixed thoroughly to terminate the reaction, yielding a reaction solution containing a block copolymer composition (α1). A portion of the resulting reaction solution was removed, and the weight-average molecular weight, content ratio, and vinyl bond content of each block copolymer and the entire block copolymer composition were determined. The results are shown in Table 1. 0.3 parts of 2,6-di-tert-butyl-p-cresol was added as an antioxidant to 100 parts of the resulting reaction solution (containing 30 parts of the polymer component), and the mixture was mixed. The mixed solution was added dropwise in small amounts to warm water heated to 85 to 95°C to volatilize the solvent, yielding a precipitate. The precipitate was then crushed and dried with hot air at 85°C to recover the block copolymer composition (α1). The melt index of the resulting block copolymer composition (α1) was measured, and the results are shown in Table 1. The solubility of the resulting block copolymer composition (α1) in styrene at 40°C was measured, and found to be 20 g / 100 g.

[0144] [Production Example 2, Acrylic Resin Production Example] 200 parts of toluene were added to a reaction vessel, and the atmosphere inside the vessel was thoroughly replaced with nitrogen while stirring the toluene. The temperature was then raised to 90°C. A mixed solution of 95 parts of methyl methacrylate, 4.6 parts of n-butyl acrylate, 0.4 parts of acrylic acid, and 2.8 parts of t-butylperoxy-2-ethylhexanoate (manufactured by NOF Corporation, trade name: Perbutyl O) was then added dropwise to the reaction vessel over 2 hours. The mixture was then held under toluene reflux for 10 hours to complete the polymerization, after which the solvent was distilled off under reduced pressure. In this way, an acrylic resin (Tg 70°C, acid value 2.5, weight average molecular weight (Mw) 11,000) was obtained.

[0145] [Table 1]

[0146] [Example 1] 74 parts of styrene and 26 parts of n-butyl acrylate as monovinyl monomers, 9 parts of carbon black (manufactured by Mitsubishi Chemical Corporation, product name: #25B) as a colorant, 0.41 parts of divinylbenzene as a crosslinkable polymerizable monomer (crosslinking agent), 1.0 part of t-dodecyl mercaptan as a molecular weight modifier, and 1 part of the acrylic resin obtained in Production Example 2 were wet-pulverized using a media-type wet pulverizer, and then 1 part of a charge control resin (styrene / acrylic resin containing a quaternary ammonium salt as a functional group, copolymerization ratio of monomer containing a quaternary ammonium salt functional group: 2%) as a charge control agent, 20 parts of behenyl stearate (number average molecular weight (Mn): 592) as a release agent, and 5 parts of the block copolymer composition (α1) obtained in Production Example 1 as an additive having a polydiene structure were added and mixed to obtain a polymerizable monomer composition.

[0147] Separately, in a stirring tank at room temperature, an aqueous solution of 4.1 parts of sodium hydroxide (alkali metal hydroxide) in 50 parts of ion-exchanged water was gradually added to an aqueous solution of 7.4 parts of magnesium chloride (a water-soluble polyvalent metal salt) in 250 parts of ion-exchanged water while stirring, to prepare a magnesium hydroxide colloid (poorly water-soluble metal hydroxide colloid) dispersion.

[0148] On the other hand, 3 parts of methyl methacrylate as a polymerizable monomer for the shell and 65 parts of ion-exchanged water were subjected to a fine dispersion treatment using an ultrasonic emulsifier to obtain an aqueous dispersion of the polymerizable monomer for the shell.

[0149] The polymerizable monomer composition was added to the magnesium hydroxide colloidal dispersion obtained above and stirred until the droplets were stabilized. 3.3 parts of t-butylperoxyisobutyrate (manufactured by NOF Corporation, trade name: Perbutyl IB) was added as a polymerization initiator, and then the mixture was stirred at a high shear rate of 15,000 rpm using an in-line emulsifying disperser (manufactured by Pacific Machinery Works, trade name: Milder) to circulate the mixture and disperse it, thereby forming droplets of the polymerizable monomer composition.

[0150] Next, 1 part of sodium tetraborate decahydrate was added to the aqueous dispersion of the polymerizable monomer composition that had formed droplets, and the mixture was placed in a reactor equipped with a stirring blade. The temperature was raised to 85°C to carry out a polymerization reaction, and after the polymerization conversion rate reached almost 100%, the temperature was raised to 95°C and polymerization was continued for another 3 hours. The reaction was then stopped by water cooling, and an aqueous dispersion of colored resin particles with a core-shell structure was obtained.

[0151] The aqueous dispersion of the colored resin particles was washed with dilute sulfuric acid (25°C, 10 minutes) to adjust the pH to 4.5 or less. After filtering the water, 200 parts of ion-exchanged water was added to re-slurry the mixture. This water washing process (washing, filtration, and dehydration) was repeated several times at room temperature (25°C). The resulting solid was filtered and separated, then vacuum-dried to obtain dried colored resin particles. The melting temperature (T1 / 2) of the resulting colored resin particles, as measured by the 1 / 2 method, the storage modulus G'(60) at 60°C, the storage modulus G'(100) at 100°C, and the storage modulus G'(150) at 150°C were measured according to the methods described above. The results are shown in Table 2.

[0152] To 100 parts of the colored resin particles obtained above, 0.5 parts of silica fine particles with a number-average primary particle size of 7 nm that had been hydrophobized with cyclic silazane and 1 part of silica fine particles with a number-average primary particle size of 35 nm that had been hydrophobized with amino-modified silicone oil were added as external additives, and the mixture was mixed and stirred using a high-speed mixer (manufactured by Nippon Coke & Engineering Co., Ltd., product name: FM Mixer) to prepare a toner for developing electrostatic images. The resulting toner for developing electrostatic images was measured and evaluated for storage stability, minimum fixing temperature, and filming on the fixing film. The results are shown in Table 2.

[0153] [Example 2] Except for changing the amount of divinylbenzene used to 0.52 parts, colored resin particles and a toner for developing electrostatic images were obtained and evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0154] [Example 3] Except for changing the amount of divinylbenzene used to 0.63 parts, colored resin particles and a toner for developing electrostatic images were obtained and evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0155] [Example 4] Except for changing the amount of divinylbenzene used to 0.68 parts, colored resin particles and a toner for developing electrostatic images were obtained and evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0156] [Example 5] Except for changing the amount of divinylbenzene used to 0.72 parts, colored resin particles and a toner for developing electrostatic images were obtained and evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0157] [Example 6] Except for changing the amount of divinylbenzene used to 0.77 parts, colored resin particles and a toner for developing electrostatic images were obtained and evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0158] [Example 7] Colored resin particles and a toner for developing electrostatic images were obtained and evaluated in the same manner as in Example 1, except that the amount of styrene used was changed to 73 parts, the amount of n-butyl acrylate used to 27 parts, the amount of divinylbenzene used to 0.65 parts, and the amount of block copolymer composition (α1) used to 3 parts. The results are shown in Table 2.

[0159] [Example 8] Colored resin particles and a toner for developing electrostatic images were obtained and evaluated in the same manner as in Example 1, except that the amount of styrene used was 74.5 parts, the amount of n-butyl acrylate used was 25.5 parts, the amount of divinylbenzene used was 0.67 parts, the amount of behenyl stearate used was 25 parts, and the amount of block copolymer composition (α1) used was 7 parts. The results are shown in Table 2.

[0160] [Comparative Example 1] Except for changing the amount of divinylbenzene used to 0.89 parts, colored resin particles and a toner for developing electrostatic images were obtained and evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0161] Comparative Example 2 Except for changing the amount of divinylbenzene used to 0.30 parts, colored resin particles and a toner for developing electrostatic images were obtained and evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0162] Comparative Example 3 Colored resin particles and a toner for developing electrostatic images were obtained and evaluated in the same manner as in Example 1, except that the amount of styrene used was changed to 70.5 parts, the amount of n-butyl acrylate used to 29.5 parts, and the amount of divinylbenzene used to 0.51 parts, and that the block copolymer composition (α1) was not used. The results are shown in Table 2.

[0163] Comparative Example 4 Colored resin particles and a toner for developing electrostatic images were obtained and evaluated in the same manner as in Example 1, except that the amount of styrene used was changed to 70.5 parts, the amount of n-butyl acrylate used to 29.5 parts, and the amount of divinylbenzene used to 0.54 parts, and that the block copolymer composition (α1) was not used. The results are shown in Table 2.

[0164] Comparative Example 5 Except for changing the amount of styrene to 77 parts, the amount of n-butyl acrylate to 23 parts, and the amount of divinylbenzene to 0.33 parts, colored resin particles and a toner for developing electrostatic images were obtained and evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0165] Comparative Example 6 Except for changing the amount of styrene to 77 parts, the amount of n-butyl acrylate to 23 parts, and the amount of divinylbenzene to 0.6 parts, colored resin particles and a toner for developing electrostatic images were obtained and evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0166] Comparative Example 7 Except for changing the amount of styrene to 72 parts, the amount of n-butyl acrylate to 28 parts, and the amount of divinylbenzene to 0.49 parts, colored resin particles and a toner for developing electrostatic images were obtained and evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0167] [Table 2]

[0168] As shown in Table 2, the colored resin particles include colored resin particles containing a binder resin, a colorant, a charge control agent, and a release agent, and the storage modulus G'(60) at 60°C is 1.0 × 10 8 ~5.0×10 8 Pa, and the storage modulus at 100°C, G'(100), is 8.0 × 10 4 ~2.3×10 5Pa, and the storage modulus at 150°C, G'(150), is 1.4 × 10 4 ~3.0×10 4 The toners of Examples 1 to 8 obtained using colored resin particles with Pa were excellent in storage stability, low-temperature fixability, and filming resistance to fixing film.

[0169] On the other hand, the toners of Comparative Examples 3, 4 and 7 obtained using colored resin particles having too small a storage modulus G'(60) at 60°C had a low storage temperature and were poor in storage stability. Furthermore, the toners of Comparative Examples 1, 5 and 6 obtained using colored resin particles having an excessively large storage modulus G'(100) at 100°C had a high minimum fixing temperature and were poor in low-temperature fixing ability. Furthermore, the toners of Comparative Examples 2 to 5 obtained using colored resin particles with too small a storage modulus G'(150) at 150°C caused filming on the fixing film, resulting in poor filming resistance on the fixing film. In addition, when obtaining the binder resins constituting the colored resin particles in Examples 1 to 8 and Comparative Examples 1 to 7, the reaction rates of styrene and n-butyl acrylate were almost 100%, and therefore, it can be said that the content ratios of styrene units and n-butyl acrylate units in the total units of the monovinyl monomer contained in the binder resin were almost the same as the charged amounts (for example, in Example 1, styrene units: 74 mass%, n-butyl acrylate units: 26 mass%).

Claims

1. A toner for developing electrostatic images, comprising colored resin particles containing a binder resin, a colorant, a charge control agent, and a release agent, In the binder resin, the content ratio of styrene-based monomer units in all monovinyl monomer units is 73 to 76 mass %, The storage modulus G'(60) of the colored resin particles at 60°C as determined by dynamic viscoelasticity measurement is 1.0 x 10 ８ ~5.0 x 10 ８ Pa, and the storage modulus G'(100) at 100°C is 8.0 × 10 ４ ~2.3 x 10 ５ Pa, and the storage modulus G'(150) at 150°C is 1.4 × 10 ４ ~3.0 x 10 ４ P A toner for developing electrostatic images.

2. 2. The toner for developing electrostatic images according to claim 1, wherein the colored resin particles have a melting temperature (T1 / 2) of 150 to 220° C. by the 1 / 2 method.

3. 3. The toner for developing electrostatic images according to claim 1, wherein the colored resin particles further contain an additive having a polydiene structure whose solubility in styrene at a temperature of 40° C. is 3 to 40 g / 100 g.

4. 4. The toner for developing electrostatic images according to claim 3, wherein the additive having a polydiene structure is a conjugated diene-aromatic vinyl thermoplastic elastomer.

5. 5. The toner for developing electrostatic images according to claim 4, wherein the additive having a polydiene structure is a block copolymer containing at least one aromatic vinyl polymer block and at least one conjugated diene polymer block.

6. 6. The toner for developing electrostatic images according to claim 1, wherein the release agent is a fatty acid ester compound having a number average molecular weight (Mn) of 500 to 1,500.

7. 7. The toner for developing electrostatic images according to claim 1, wherein the ratio G'(100) / G'(150) of the storage modulus G'(100) at 100°C to the storage modulus G'(150) at 150°C of the colored resin particles is 3.0 to 15.0.

Images