Electrostatic charge image developing toner

Abstract

To provide electrostatic charge image developing toner excellent in charging property and durability under high temperature and high humidity.SOLUTION: The electrostatic charge image developing toner contains a binder resin containing an amorphous polyester resin and a crystalline polyester resin, wherein the crystalline polyester resin contains a crystalline block polymer (C) in which an amorphous polyester segment (a) and a crystalline polyester segment (c) obtained by ring-opening polymerization of a cyclic lactone are bonded via an ester bond.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] Patent Document 1 discloses a toner comprising resin particles (C) having a first resin (a1) and a second resin (a2) having different glass transition points, and resin particles (B) containing a third resin (b), wherein the first resin (a1) and the second resin (a2) are attached to the surface of the resin particles (B), and the third resin (b) has a non-crystalline polyhydroxycarboxylic acid skeleton.

[0003] Patent Document 2 discloses a method for producing a dispersion (Z1) in which organic fine particles (A) are fixed to the surface of resin particles (Y1) containing resin (B), colorant (k), solvent (S), and wax (w) by dispersing a solution (L) of resin (B) in solvent (S), colorant dispersion (C), and, if necessary, wax dispersion (D) in carbon dioxide (X) in a liquid state or a supercritical state in which organic fine particles (A) are dispersed, and the method further comprises the steps of treating (Z1) with (X), and then removing (X) and (S) from dispersion (Q) in which the obtained (Z1) is dispersed in a dispersion medium containing (X) and (S). The present invention discloses a method for producing resin particles (Z), in which resin (B) is a resin composed of a crystalline portion (a) and a non-crystalline portion (b) having lactone ring-opening polymer (p) as an essential component, and colorant dispersion (C) is a dispersion in which colorant (k), a dispersant (l) having an acid value and an amine value of 20 to 250 in total (mgKOH / g), a solvent (S), and carbon dioxide (X) in a liquid or supercritical state with a pressure of 2 MPa or more, are mixed, and then the mixture is expanded under reduced pressure to vaporize and remove (X), thereby obtaining colorant dispersion (C), in which (k) with a median diameter of 1 μm or less is dispersed in (S).

[0004] Patent Document 3 discloses a toner having base particles containing a block copolymer having a polyester block A and a polyester block B having a fluoro group, wherein, when a cross-sectional phase image of the block copolymer is observed using a tapping mode atomic force microscope, domains derived from the polyester block B, which have a large phase delay, are dispersed in domains derived from the polyester block A, which have a small phase delay, and the domains derived from the polyester block B have an average domain size of 10 nm or more and 45 nm or less.

[0005] Patent Document 4 discloses an image forming method including a latent image forming step of forming an electrostatic latent image on the surface of a latent image holder, a developing step of developing the electrostatic latent image formed on the surface of the latent image holder with an electrostatic image developing toner or an electrostatic image developer containing the toner and a carrier to form a toner image, a step of transferring the toner image formed on the surface of the latent image holder to a surface of a transfer recipient, and a fixing step of pressurizing and fixing the toner image transferred to the surface of the transfer recipient, wherein the toner contains a block copolymer having a crystalline polyester block and a non-crystalline polyester block, and the maximum pressure during the fixing is 1 MPa or more and 10 MPa or less. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2011-53657 A [Patent Document 2] JP 2011-94137 A [Patent Document 3] JP 2013-80052 A [Patent Document 4] JP 2007-114635 A Summary of the Invention [Problem to be solved by the invention]

[0007] In order to improve low-temperature fixing properties as a binder resin for toner, the use of an amorphous polyester resin in combination with a crystalline polyester resin has been investigated.

[0008] However, although the low-temperature fixing property is improved by the crystalline polyester resin, when the crystalline polyester resin is exposed on the surface of the toner particles, the chargeability and durability are deteriorated. In particular, under high temperature and high humidity conditions, the toner surface is plasticized to a greater extent, so that the deterioration of the chargeability and durability is remarkable.

[0009] The present invention relates to a toner for developing electrostatic images, which has excellent chargeability and durability under high temperature and high humidity conditions. [Means for solving the problem]

[0010] The present invention relates to a toner for developing electrostatic images, which contains a binder resin that contains an amorphous polyester resin and a crystalline polyester resin, and the crystalline polyester resin contains a crystalline block polymer (C) in which an amorphous polyester segment (a) and a crystalline polyester segment (c) obtained by ring-opening polymerization of a cyclic lactone are bonded via an ester bond. Effect of the Invention

[0011] The toner for developing electrostatic images of the present invention exhibits excellent effects in terms of chargeability and durability under high temperature and high humidity conditions. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The toner for developing electrostatic images of the present invention contains an amorphous polyester resin and a crystalline block polymer (C) in which an amorphous polyester segment (a) and a crystalline polyester segment (c) formed by ring-opening polymerization of a cyclic lactone are bonded via an ester bond. Although the details of why the effects of the present invention are exhibited are not clear, it is presumed as follows.

[0013] In the present invention, the crystalline polyester resin can be efficiently dispersed in the amorphous polyester resin by using the crystalline block polymer (C) in which the terminal of the crystalline polyester is modified with an amorphous polyester. Generally, highly hydrophobic crystalline polyester resin is difficult to disperse in the amorphous polyester resin, and it is difficult to maintain a high dispersion state in the toner. In contrast, the crystalline block polymer (C) in the present invention is formed by ring-opening polymerization of cyclic lactones equally from the terminal of the amorphous polyester segment (a), so that the composition distribution of the crystalline polyester segment (c) is narrow and there are very few unreacted unblocked crystalline polyester segments. As a result, the crystalline block polymer (C) in which the terminal of the crystalline polyester is modified with an amorphous polyester has improved dispersibility in the toner and is suppressed from being exposed to the toner surface, so that the toner of the present invention is considered to have a significantly improved chargeability and durability even under high temperature and high humidity conditions.

[0014] In the present invention, the crystalline polyester resin contains a crystalline block polymer (C) in which an amorphous polyester segment (a) and a crystalline polyester segment (c) formed by ring-opening polymerization of a cyclic lactone are bonded via an ester bond.

[0015] The amorphous polyester segment (a) is formed by polycondensation of an alcohol component and a carboxylic acid component.

[0016] As the alcohol component, from the viewpoint of electrostatic chargeability, a compound represented by the formula (I):

[0017] [ka]

[0018] (In the formula, OR and RO are oxyalkylene groups, R is an ethylene group and / or a propylene group, x and y are the average number of moles of alkylene oxide added, each of which is a positive number, and the sum of x and y is 1 or more, preferably 1.5 or more, and 16 or less, preferably 8 or less, more preferably 6 or less, and even more preferably 4 or less.) The alkylene oxide adduct of bisphenol A represented by formula (I) is preferably a compound represented by the formula (I). Examples of the alkylene oxide adduct of bisphenol A represented by formula (I) include a polyoxypropylene adduct of 2,2-bis(4-hydroxyphenyl)propane, a polyoxyethylene adduct of 2,2-bis(4-hydroxyphenyl)propane, etc. It is preferable to use one or more of these.

[0019] The content of the alkylene oxide adduct of bisphenol A represented by formula (I) in the alcohol component is preferably 70 mol % or more, more preferably 80 mol % or more, even more preferably 90 mol % or more, even more preferably 95 mol % or more, and even more preferably 100 mol %.

[0020] Examples of other alcohol components include aliphatic diols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-butenediol, 1,3-butanediol, and neopentyl glycol; and trihydric or higher alcohols such as bisphenol A, hydrogenated bisphenol A, and glycerin.

[0021] As the carboxylic acid component, from the viewpoint of chargeability under high temperature and high humidity conditions, an aromatic dicarboxylic acid compound is preferred.

[0022] Examples of the aromatic dicarboxylic acid compound include phthalic acid, isophthalic acid, terephthalic acid, anhydrides of these acids, and alkyl esters having an alkyl group with a carbon number of 1 to 3. Among these, from the viewpoint of low-temperature fixability, terephthalic acid or isophthalic acid is preferred, and terephthalic acid is more preferred.

[0023] From the viewpoint of low-temperature fixing property, the content of the aromatic dicarboxylic acid compound in the carboxylic acid component is preferably 70 mol % or more, more preferably 80 mol % or more, even more preferably 90 mol % or more, even more preferably 95 mol % or more, and even more preferably 100 mol %.

[0024] Examples of other carboxylic acid components include fumaric acid, maleic acid, succinic acid, succinic acid derivatives substituted with a hydrocarbon group, aliphatic dicarboxylic acids such as glutaric acid, adipic acid, and sebacic acid, trivalent or higher carboxylic acids such as trimellitic acid and pyromellitic acid, anhydrides of these acids, and alkyl esters of these acids having 1 to 3 carbon atoms.

[0025] The alcohol component may appropriately contain a monohydric alcohol, and the carboxylic acid component may appropriately contain a monovalent carboxylic acid compound.

[0026] In this specification, macromonomers and hydroxycarboxylic acids are not included in the alcohol component and the carboxylic acid component.

[0027] The equivalent ratio of the carboxy group of the carboxylic acid component to the hydroxyl group of the alcohol component (COOH group / OH group) is preferably 0.6 or more, more preferably 0.7 or more, even more preferably 0.75 or more, and is preferably 1.2 or less, more preferably 1.15 or less.

[0028] The amorphous polyester segment (a) can be formed, for example, by polycondensing an alcohol component and a carboxylic acid component, which are raw material monomers, in an inert gas atmosphere, preferably in the presence of an esterification catalyst, and further, if necessary, in the presence of an esterification promoter, a polymerization inhibitor, etc., at a temperature of preferably 160° C. or higher, more preferably 200° C. or higher, and preferably 250° C. or lower, more preferably 240° C. or lower.

[0029] Examples of the esterification catalyst include tin compounds such as dibutyltin oxide and tin(II) 2-ethylhexanoate, and titanium compounds such as titanium diisopropylate bistriethanolamine. The amount of the esterification catalyst used is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, and preferably 1.5 parts by mass or less, more preferably 1 part by mass or less, relative to 100 parts by mass of the raw material monomer. Examples of the esterification promoter include gallic acid, etc. The amount of the esterification promoter used is preferably 0.001 parts by mass or more, more preferably 0.01 parts by mass or more, and preferably 0.5 parts by mass or less, more preferably 0.1 parts by mass or less, relative to 100 parts by mass of the raw material monomer. Examples of the polymerization inhibitor include tert-butylcatechol, etc. The amount of the polymerization inhibitor used is preferably 0.001 parts by mass or more, more preferably 0.01 parts by mass or more, and preferably 0.5 parts by mass or less, more preferably 0.1 parts by mass or less, relative to 100 parts by mass of the raw material monomer.

[0030] The crystalline polyester segment (c) is formed by ring-opening polymerization of a cyclic lactone.

[0031] Examples of cyclic lactones include ε-caprolactone, β-propiolactone, γ-butyrolactone, δ-valerolactone, and the like. Among these, ε-caprolactone is preferred from the viewpoint of durability under high temperature and high humidity conditions.

[0032] The ring-opening polymerization of the cyclic lactone can be carried out, for example, by mixing the amorphous polyester segment (a) with the cyclic lactone and heating the mixture to about 80 to 140°C.

[0033] In the crystalline block polymer (C), the mass ratio of the amorphous polyester segment (a) to the crystalline polyester segment (c) (amorphous polyester segment (a) / crystalline polyester segment (c)) is preferably 2 / 98 or more, more preferably 5 / 95 or more, and even more preferably 10 / 90 or more from the viewpoint of durability under high temperature and high humidity conditions, and is preferably 40 / 60 or less, more preferably 30 / 70 or less, and even more preferably 20 / 80 or less from the viewpoint of low temperature fixability.

[0034] The softening point of the crystalline block polymer (C) is preferably 40° C. or higher, more preferably 45° C. or higher, and even more preferably 50° C. or higher, from the viewpoint of heat-resistant storage stability, and is preferably 70° C. or lower, and more preferably 60° C. or lower, from the viewpoint of low-temperature fixability.

[0035] The crystallinity of a resin is represented by a crystallinity index defined as the ratio of the softening point to the maximum endothermic peak temperature measured by a differential scanning calorimeter, that is, the value of [softening point / maximum endothermic peak temperature]. The crystalline resin is a resin having a crystallinity index of 0.6 or more, preferably 0.7 or more, more preferably 0.9 or more, and 1.4 or less, preferably 1.2 or less, more preferably 1.1 or less. On the other hand, an amorphous resin is a resin in which no endothermic peak is observed, or if an endothermic peak is observed, the crystallinity index is greater than 1.4, preferably greater than 1.5, more preferably 1.6 or more, or less than 0.6, preferably 0.5 or less. The crystallinity of the resin can be adjusted by the type and ratio of the raw material monomers, and the production conditions (e.g., reaction temperature, reaction time, cooling rate), etc. The maximum endothermic peak temperature refers to the temperature of the peak with the largest peak area among the observed endothermic peaks. In the case of a crystalline resin, the maximum endothermic peak temperature is the melting point.

[0036] The melting point of the crystalline block polymer (C) is preferably 40° C. or higher, more preferably 45° C. or higher, and even more preferably 48° C. or higher, from the viewpoint of heat-resistant storage stability, and is preferably 70° C. or lower, and more preferably 60° C. or lower, from the viewpoint of low-temperature fixability.

[0037] From the viewpoint of electrostatic stability, the acid value of the crystalline block polymer (C) is preferably 2 mgKOH / g or more, more preferably 4 mgKOH / g or more, and preferably 20 mgKOH / g or less, more preferably 15 mgKOH / g or less, and even more preferably 10 mgKOH / g or less.

[0038] From the viewpoint of electrostatic charge stability, the hydroxyl value of the crystalline block polymer (C) is preferably 5 mgKOH / g or more, more preferably 10 mgKOH / g or more, and preferably 50 mgKOH / g or less, more preferably 35 mgKOH / g or less.

[0039] The content of the crystalline block polymer (C) in the crystalline polyester resin is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and still more preferably 100% by mass.

[0040] The content of the crystalline block polymer (C) in the binder resin is preferably 2 mass% or more, more preferably 5 mass% or more, even more preferably 8 mass% or more, and preferably 30 mass% or less, more preferably 25 mass% or less, even more preferably 15 mass% or less.

[0041] The content of the crystalline polyester resin in the binder resin is preferably 2% by mass or more, more preferably 5% by mass or more, even more preferably 8% by mass or more, and preferably 30% by mass or less, more preferably 25% by mass or less, even more preferably 15% by mass or less.

[0042] The amorphous polyester resin is preferably a polycondensation product of an alcohol component containing an alkylene oxide adduct of bisphenol A represented by the above formula (I) and a carboxylic acid component containing an aromatic dicarboxylic acid compound.

[0043] The content of the alkylene oxide adduct of bisphenol A represented by formula (I) in the alcohol component is preferably 70 mol % or more, more preferably 80 mol % or more, even more preferably 90 mol % or more, even more preferably 95 mol % or more, and even more preferably 100 mol %.

[0044] Examples of other alcohol components include aliphatic diols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-butenediol, 1,3-butanediol, and neopentyl glycol; and trihydric or higher alcohols such as bisphenol A, hydrogenated bisphenol A, and glycerin.

[0045] Examples of the aromatic dicarboxylic acid compound include the same compounds as those mentioned above, with terephthalic acid being preferred.

[0046] The content of the aromatic dicarboxylic acid compound in the carboxylic acid component is preferably 30 mol% or more, more preferably 35 mol% or more, even more preferably 40 mol% or more, and is preferably 80 mol% or less, more preferably 70 mol% or less, even more preferably 60 mol% or less.

[0047] Examples of the carboxylic acid component other than the aromatic dicarboxylic acid compound include an aliphatic dicarboxylic acid compound and a trivalent or higher carboxylic acid compound.

[0048] Examples of the aliphatic dicarboxylic acid compound include aliphatic dicarboxylic acids such as oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid which may be substituted with a hydrocarbon group, and adipic acid, as well as anhydrides of these acids and alkyl esters in which the alkyl group has 1 to 3 carbon atoms.

[0049] The content of the aliphatic dicarboxylic acid compound in the carboxylic acid component is 0 mol% or more, preferably 5 mol% or more, more preferably 10 mol% or more, and preferably 40 mol% or less, more preferably 30 mol% or less, and even more preferably 20 mol% or less.

[0050] Examples of the trivalent or higher carboxylic acid compound include trimellitic acid, pyromellitic acid, anhydrides of these acids, and alkyl esters of these acids having 1 to 3 carbon atoms.

[0051] From the viewpoint of increasing the softening point, the content of the trivalent or higher carboxylic acid compound in the carboxylic acid component is preferably 10 mol % or more, more preferably 20 mol % or more, and is preferably 40 mol % or less, more preferably 35 mol % or less.

[0052] The alcohol component may appropriately contain a monohydric alcohol, and the carboxylic acid component may appropriately contain a monovalent carboxylic acid compound.

[0053] From the viewpoint of adjusting the softening point of the polyester resin, the equivalent ratio of the carboxy group of the carboxylic acid component to the hydroxyl group of the alcohol component (COOH group / OH group) is preferably 0.6 or more, more preferably 0.7 or more, even more preferably 0.75 or more, and is preferably 1.2 or less, more preferably 1.15 or less.

[0054] The amorphous polyester resin can be produced by polycondensing an alcohol and a carboxylic acid compound in the same manner as in the production of the amorphous polyester segment (a).

[0055] In the present invention, the polyester resin may be modified to such an extent that its properties are not substantially impaired. Examples of modified polyester resins include polyester resins grafted or blocked with phenol, urethane, epoxy, or the like, by the methods described in JP-A-11-133668, JP-A-10-239903, JP-A-8-20636, and the like.

[0056] The softening point of the amorphous polyester resin is preferably 120°C or higher, more preferably 125°C or higher, and even more preferably 130°C or higher from the viewpoint of hot offset resistance, and is preferably 160°C or lower, more preferably 150°C or lower, and even more preferably 145°C or lower from the viewpoint of low-temperature fixability.

[0057] The glass transition temperature of the amorphous polyester resin is preferably 45° C. or higher, more preferably 50° C. or higher, and even more preferably 53° C. or higher, from the viewpoint of heat-resistant storage stability, and is preferably 80° C. or lower, and more preferably 70° C. or lower, from the viewpoint of low-temperature fixability.

[0058] From the viewpoint of charging stability, the acid value of the amorphous polyester resin is preferably 5 mgKOH / g or more, more preferably 10 mgKOH / g or more, and preferably 40 mgKOH / g or less, more preferably 30 mgKOH / g or less.

[0059] From the viewpoint of charging stability, the hydroxyl value of the amorphous polyester resin is preferably 5 mgKOH / g or more, more preferably 10 mgKOH / g or more, and preferably 50 mgKOH / g or less, more preferably 40 mgKOH / g or less.

[0060] The content of the amorphous polyester resin in the binder resin is preferably 70% by mass or more, more preferably 75% by mass or more, even more preferably 85% by mass or more, and preferably 98% by mass or less, more preferably 95% by mass or less, even more preferably 92% by mass or less.

[0061] From the viewpoint of heat-resistant storage stability, the mass ratio of the amorphous polyester resin to the crystalline block polymer (C) (amorphous polyester resin / crystalline block polymer (C)) is preferably 70 / 30 or more, more preferably 75 / 25 or more, and even more preferably 85 / 15 or more, and from the viewpoint of low-temperature fixability, it is preferably 98 / 2 or less, more preferably 95 / 5 or less, and even more preferably 92 / 8 or less.

[0062] From the viewpoint of heat-resistant storage stability, the mass ratio of the amorphous polyester resin to the crystalline polyester resin (amorphous polyester resin / crystalline polyester resin) is preferably 70 / 30 or more, more preferably 75 / 25 or more, and even more preferably 85 / 15 or more, and from the viewpoint of low-temperature fixability, it is preferably 98 / 2 or less, more preferably 95 / 5 or less, and even more preferably 92 / 8 or less.

[0063] The binder resin may contain resins other than the above-mentioned amorphous polyester resin and crystalline polyester resin within a range that does not impair the effects of the present invention. Examples of other resins include vinyl resins such as styrene-acrylic resin, epoxy resin, polycarbonate, polyurethane, and composite resins containing two or more of these resins.

[0064] The total content of the amorphous polyester resin and the crystalline polyester resin in the binder resin is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and still more preferably 98% by mass or more, and 100% by mass or less.

[0065] The content of the binder resin in the toner is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, and is preferably 99% by mass or less, more preferably 98% by mass or less, even more preferably 95% by mass or less.

[0066] The toner for developing electrostatic images of the present invention may contain additives such as a colorant, a release agent, a charge control agent, a magnetic powder, a flowability improver, a conductivity adjuster, a reinforcing filler such as a fibrous substance, an antioxidant, and a cleaning property improver, in addition to the binder resin.

[0067] As the colorant, dyes, pigments, magnetic materials, etc. used as colorants for toners can be used. For example, carbon black, phthalocyanine blue, permanent brown FG, brilliant fast scarlet, pigment red 122, pigment green B, rhodamine-B base, solvent red 49, solvent red 146, solvent blue 35, quinacridone, carmine 6B, isoindoline, disazo yellow, etc. can be mentioned. In the present invention, the toner may be either a black toner or a color toner.

[0068] From the viewpoint of improving the image density and low-temperature fixability of the toner, the content of the colorant is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and preferably 40 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less, relative to 100 parts by mass of the binder resin.

[0069] Examples of the release agent include hydrocarbon waxes such as polypropylene wax, polyethylene wax, polypropylene-polyethylene copolymer wax, microcrystalline wax, paraffin wax, and Fischer-Tropsch wax, and oxides thereof; ester waxes such as carnauba wax, montan wax, and deacidified waxes thereof, and fatty acid ester wax; fatty acid amides, fatty acids, higher alcohols, and fatty acid metal salts. These may be used alone or in combination of two or more.

[0070] The melting point of the release agent is preferably 60° C. or higher, more preferably 70° C. or higher, from the viewpoint of toner transferability, and is preferably 160° C. or lower, more preferably 140° C. or lower, even more preferably 120° C. or lower, and even more preferably 110° C. or lower, from the viewpoint of low-temperature fixability.

[0071] The content of the release agent is, from the viewpoint of the low-temperature fixing property and offset resistance of the toner and the viewpoint of dispersibility in the binder resin, preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, even more preferably 1.5 parts by mass or more, and is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, even more preferably 7 parts by mass or less, relative to 100 parts by mass of the binder resin.

[0072] The charge control agent is not particularly limited, and may contain either a positively chargeable charge control agent or a negatively chargeable charge control agent.

[0073] Examples of the positively charged charge control agent include nigrosine dyes such as "Nigrosine Base EX", "Oil Black BS", "Oil Black SO", "Bontron N-01", "Bontron N-04", "Bontron N-07", "Bontron N-09", and "Bontron N-11" (all manufactured by Orient Chemical Industries Co., Ltd.); triphenylmethane dyes containing a tertiary amine as a side chain; quaternary ammonium salt compounds such as "Bontron P-51" (manufactured by Orient Chemical Industries Co., Ltd.), cetyltrimethylammonium bromide, and "COPY CHARGE PX Examples of such resins include "VP435" (manufactured by Clariant), etc.; polyamine resins, such as "AFP-B" (manufactured by Orient Chemical Industry Co., Ltd.); imidazole derivatives, such as "PLZ-2001" and "PLZ-8001" (both manufactured by Shikoku Kasei Corporation); and styrene-acrylic resins, such as "FCA-701PT" and "FCA-201-PS" (manufactured by Fujikura Kasei Co., Ltd.).

[0074] Examples of the negatively chargeable charge control agent include metal-containing azo dyes such as "Varifast Black 3804", "Bontron S-31", "Bontron S-32", "Bontron S-34", and "Bontron S-36" (all manufactured by Orient Chemical Industry Co., Ltd.), "Aizenspiron Black TRH", and "T-77" (manufactured by Hodogaya Chemical Industry Co., Ltd.); metal compounds of benzilic acid compounds such as "LR-147" and "LR-297" (all manufactured by Nippon Carlit Co., Ltd.); metal compounds of salicylic acid compounds such as "Bontron E-81", "Bontron E-84", "Bontron E-88", and "Bontron E-304" (all manufactured by Orient Chemical Industry Co., Ltd.), and "TN-105" (manufactured by Hodogaya Chemical Industry Co., Ltd.); copper phthalocyanine dyes; and quaternary ammonium salts such as "COPY CHARGE NX VP434 (Clariant), nitroimidazole derivatives, and organometallic compounds.

[0075] From the viewpoint of the charging stability of the toner, the content of the charge control agent is preferably 0.01 parts by mass or more, more preferably 0.2 parts by mass or more, and preferably 10 parts by mass or less, more preferably 5 parts by mass or less, even more preferably 3 parts by mass or less, and even more preferably 2 parts by mass or less, relative to 100 parts by mass of the binder resin.

[0076] The toner of the present invention may be a toner obtained by any of the conventionally known methods such as a melt-kneading method, an emulsion phase inversion method, a polymerization method, etc., but from the viewpoint of durability under high temperature and high humidity, a pulverized toner by a melt-kneading method is preferred. In the case of a pulverized toner by a melt-kneading method, for example, it is obtained by a method including a step of melt-kneading a mixture containing the above-mentioned crystalline block polymer (C) and an amorphous polyester resin, and further, if necessary, additives such as a colorant, a release agent, and a charge control agent (melt-kneading step).

[0077] The mixture to be melt-kneaded may be kneaded all at once or in portions, but it is preferable to previously mix the mixture in a mixer such as a Henschel mixer or a ball mill and then feed the mixture to the kneader.

[0078] The melt kneading can be carried out using a known kneading machine such as an internal kneader, a single-screw or twin-screw extruder, or an open roll type kneader.

[0079] The melt-kneading temperature is not particularly limited as long as the resin is melted and mixed at the temperature.

[0080] After the melt-kneading step, it is preferable to appropriately cool the kneaded mixture until it reaches a pulverizable hardness, and then, if necessary, perform a pulverizing step and a classification step to obtain toner particles. Here, cooling refers to cooling the kneaded mixture to 0°C or higher and 50°C or lower, or cooling to the glass transition temperature of the binder resin in the kneaded mixture or lower.

[0081] In the toner of the present invention, it is preferable to use an external additive in order to improve transferability.The external additive includes inorganic fine particles such as silica, alumina, titania, zirconia, tin oxide, zinc oxide, etc., and organic fine particles such as resin particles such as melamine resin fine particles and polytetrafluoroethylene resin fine particles, and two or more kinds may be used in combination.Among these, silica is preferable, and from the viewpoint of transferability of the toner, hydrophobic silica that has been hydrophobized is more preferable.

[0082] Examples of hydrophobic treatment agents for hydrophobizing the surface of silica particles include hexamethyldisilazane (HMDS), dimethyldichlorosilane (DMDS), cyclic silazane, silicone oil, aminosilane, octyltriethoxysilane (OTES), and methyltriethoxysilane.

[0083] From the viewpoint of the chargeability, fluidity, and transferability of the toner, the average particle size of the external additive is preferably 10 nm or more, more preferably 15 nm or more, and is preferably 250 nm or less, more preferably 200 nm or less, and even more preferably 90 nm or less.

[0084] A mixer such as a Henschel mixer can be used to mix the toner particles and the external additives.

[0085] From the viewpoint of the electrostatic chargeability, fluidity, and transferability of the toner, the content of the external additive is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, and even more preferably 0.3 parts by mass or more, relative to 100 parts by mass of the toner particles before being treated with the external additive, and is preferably 5 parts by mass or less, and more preferably 3 parts by mass or less.

[0086] The volume median particle size (D 50 ) is preferably 3 μm or more, more preferably 4 μm or more, and is preferably 15 μm or less, more preferably 10 μm or less. 50 ) refers to the particle size at which the cumulative volume frequency calculated by volume fraction is 50% calculated from the smallest particle size. In addition, when the toner is treated with an external additive, the volume median particle size of the toner particles before treatment with the external additive is regarded as the volume median particle size of the toner.

[0087] The toner of the present invention can be used as it is as a toner for one-component development, or as a toner for two-component development mixed with a carrier, in an image forming apparatus of a one-component development system or a two-component development system, respectively. EXAMPLES

[0088] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. Physical properties of resins and the like can be measured by the following methods.

[0089] [Softening point of resin] Using a flow tester "CFT-500D" (Shimadzu Corporation), 1g of sample is heated at a temperature increase rate of 6℃ / min while applying a load of 1.96MPa with the plunger, and extruding the sample from a nozzle with a diameter of 1mm and a length of 1mm. The amount of plunger descent of the flow tester is plotted against the temperature, and the temperature at which half of the sample has flowed out is taken as the softening point.

[0090] [Maximum endothermic peak temperature of resin] Using a differential scanning calorimeter "Q-100" (manufactured by TA Instruments Japan, Inc.), weigh 0.01 to 0.02 g of sample into an aluminum pan, cool from room temperature (25°C) to 0°C at a rate of 10°C / min, and maintain at 0°C for 1 minute. Then, measure at a rate of 10°C / min. The temperature of the peak with the largest peak area among the observed endothermic peaks is regarded as the maximum endothermic peak temperature.

[0091] [Glass transition temperature of resin] Using a differential scanning calorimeter "Q-100" (manufactured by TA Instruments Japan), 0.01 to 0.02 g of sample is weighed into an aluminum pan, heated to 200°C, and cooled from that temperature at a rate of 10°C / min to 0°C. Next, the sample is heated at a rate of 10°C / min, and the endothermic peak is measured. The glass transition temperature is the temperature at the intersection of the extension of the baseline below the maximum endothermic peak temperature and the tangent line showing the maximum slope from the rising part of the peak to the top of the peak.

[0092] [Acid value of resin] Measurements are performed based on the method of JIS K 0070:1992, except that the measurement solvent is changed from the ethanol and ether mixture specified in JIS K 0070 to a mixture of acetone and toluene (acetone:toluene = 1:1 (volume ratio)) for amorphous resins, and a mixture of chloroform and dimethylformamide (chloroform:dimethylformamide = 7:3 (volume ratio)) for crystalline resins.

[0093] [Hydroxyl value of resin] Measure based on the method of JIS K 0070:1992, except that the measurement solvent is changed from the ethanol and ether mixture specified in JIS K 0070 to tetrahydrofuran.

[0094] [Melting point of release agent] Using a differential scanning calorimeter "DSC 210" (manufactured by TA Instruments Japan Co., Ltd.), weigh 0.01 to 0.02 g of sample into an aluminum pan, heat it to 200°C at a heating rate of 10°C / min, and then cool it to -10°C at a cooling rate of 5°C / min. Next, heat the sample to 180°C at a heating rate of 10°C / min and measure. The maximum endothermic peak temperature observed from the melting endothermic curve obtained is the melting point of the release agent.

[0095] [Average particle size of external additives] The average particle size refers to the number-average particle size, and is calculated by measuring the particle sizes (average of major and minor diameters) of 500 particles in a scanning electron microscope (SEM) photograph and averaging these by number.

[0096] [Volume Median Particle Size of Toner] Measuring instrument: Coulter Multisizer III (manufactured by Beckman Coulter, Inc.) Aperture diameter: 50μm Analysis software: Multisizer III version 3.51 (Beckman Coulter, Inc.) Electrolyte: "Isoton (registered trademark) II" (manufactured by Beckman Coulter, Inc.) Dispersion liquid: Polyoxyethylene lauryl ether "Emulgen (registered trademark) 109P" (manufactured by Kao Corporation, HLB (Griffin) = 13.6) was dissolved in the electrolyte to adjust the concentration to 5% by mass. Dispersion conditions: 10 mg of the measurement sample is added to 5 mL of the dispersion liquid, and dispersed for 1 minute using an ultrasonic disperser (machine name: US-1, manufactured by SND Co., Ltd., output: 80 W). Then, 25 mL of electrolyte is added, and the mixture is further dispersed for 1 minute using the ultrasonic disperser to prepare a sample dispersion liquid. Measurement conditions: The sample dispersion was added to 100 mL of the electrolyte to adjust the concentration so that the particle size of 30,000 particles could be measured in 20 seconds. Then, 30,000 particles were measured, and the volume median particle size (D 50 ) is required.

[0097] Resin manufacturing example 1 The alcohol components shown in Table 1, carboxylic acid components other than trimellitic anhydride, and esterification catalyst were placed in a 10-liter four-neck flask equipped with a thermometer, a stainless steel stirring rod, a downflow condenser equipped with a dehydration tube, and a nitrogen inlet tube, and the mixture was heated to 230°C in a mantle heater in a nitrogen atmosphere and reacted for 8 hours. Thereafter, trimellitic anhydride shown in Table 1 was added, the mixture was heated to 220°C, and the reaction was carried out at 8.0 kPa to obtain an amorphous polyester resin (resin A1).

[0098] Resin manufacturing example 2 The alcohol components shown in Table 1, carboxylic acid components other than trimellitic anhydride, and esterification catalyst were placed in a 10-liter four-neck flask equipped with a thermometer, a stainless steel stirring rod, a downflow condenser equipped with a dehydration tube, and a nitrogen inlet tube, and the temperature was raised from 180°C to 230°C over 4 hours in a mantle heater in a nitrogen atmosphere, and the reaction was carried out at 230°C for 6 hours. Thereafter, trimellitic anhydride shown in Table 1 was added, the temperature was raised to 220°C, and the reaction was carried out at 8.0 kPa to obtain amorphous polyester resins (resins A2 and A3).

[0099] [Table 1]

[0100] Resin manufacturing example 3 The alcohol component, carboxylic acid component, and esterification catalyst shown in Table 2 were placed in a 10-liter four-neck flask equipped with a thermometer, a stainless steel stirring rod, a downflow condenser equipped with a dehydration tube, and a nitrogen inlet tube, and the temperature was raised to 230°C in a mantle heater in a nitrogen atmosphere and reacted for 8 hours. The reaction was carried out at 8.0 kPa to synthesize an amorphous polyester segment. Thereafter, the cyclic lactone shown in Table 2 was added at 120°C and reacted for 2 hours, and then the reaction was carried out at 8.0 kPa until the softening point shown in Table 2 was reached, to obtain crystalline block polymers (resins B1 to B5).

[0101] [Table 2]

[0102] Resin manufacturing example 4 The alcohol component C and the carboxylic acid component C shown in Table 3 were placed in a 10-liter four-neck flask equipped with a thermometer, a stainless steel stirring rod, a downflow condenser, and a nitrogen inlet tube, and the temperature was raised to 200°C over 8 hours in a nitrogen atmosphere in a mantle heater. Then, the esterification catalyst C shown in Table 3 was added, and the reaction was carried out at 8.0 kPa until the softening point shown in Table 3 was reached, to obtain a crystalline polyester resin (resin C1).

[0103] Resin manufacturing example 5 The alcohol component A, carboxylic acid component A, and esterification catalyst A shown in Table 3 were placed in a 10-liter four-neck flask equipped with a thermometer, a stainless steel stirring rod, a downflow condenser equipped with a dehydration tube, and a nitrogen inlet tube, and the mixture was heated to 230°C in a mantle heater in a nitrogen atmosphere and reacted for 8 hours. The reaction was carried out at 8.0 kPa to obtain an amorphous polyester resin. Meanwhile, alcohol component C and carboxylic acid component C shown in Table 3 were placed in a 10-liter four-neck flask equipped with a thermometer, a stainless steel stirring rod, a downflow condenser, and a nitrogen inlet tube, and the temperature was raised to 200°C over 8 hours in a nitrogen atmosphere in a mantle heater. Then, esterification catalyst C shown in Table 3 was added, and the reaction was carried out at 8.0 kPa until the softening point shown in Table 3 was reached, to obtain a crystalline polyester resin. Thereafter, the amorphous polyester resin was added at 160° C. and reacted with the crystalline polyester resin for 2 hours to obtain a crystalline block polymer (resin C2).

[0104] [Table 3]

[0105] Examples 1 to 9 and Comparative Examples 1 and 2 100 parts by mass of the binder resin shown in Table 4, 5 parts by mass of the colorant "ECB-301" (Dainichi Seika Chemicals Co., Ltd., Phthalocyanine Blue), 1 part by mass of the charge control agent "LR-147" (Nippon Carlit Co., Ltd.), and 3 parts by mass of the release agent ("Carnauba Wax C1" (Kato Yoko Co., Ltd., melting point: 80°C)) were thoroughly stirred with a Henschel mixer, and then melt-kneaded using a co-rotating twin-screw extruder with a kneading section total length of 1560 mm, a screw diameter of 42 mm, and a barrel inner diameter of 43 mm. The rotation speed of the roll was 200 r / min, the heating temperature setting in the roll was 90°C, the temperature of the kneaded material was 140°C, the feed rate of the kneaded material was 10 kg / h, and the average residence time was about 18 seconds. The kneaded product was cooled from 140°C to 50°C in 1.5 hours, rolled and cooled at 50°C with a cooling roller, and then allowed to stand at 45°C for 4 hours. The volume median particle size (D 50 ) Toner particles of 5.5 μm were obtained.

[0106] To 100 parts by mass of the obtained toner particles, 1.5 parts by mass of hydrophobic silica "Aerosil R-972" (manufactured by Nippon Aerosil Co., Ltd., hydrophobic treatment agent: DMDS, average particle size: 16 nm) and 1.0 part by mass of hydrophobic silica "RY-50" (manufactured by Nippon Aerosil Co., Ltd., hydrophobic treatment agent: silicone oil, average particle size: 40 nm) were added as external additives, and the mixture was mixed in a Henschel mixer at 3600 r / min for 5 minutes to perform external additive treatment and obtain a toner.

[0107] Test Example 1 [Durability under high temperature and high humidity (HH) conditions] The toner was loaded onto a laser printer "Page Presto N-4" (Casio Computer Co., Ltd., fixing: contact fixing method, development: non-magnetic one-component development method, development roll diameter: 2.3 cm), and printing was performed with a diagonal stripe pattern with a blackening rate of 5.5% under high temperature and high humidity conditions of a temperature of 40°C and a relative humidity of 85%. During the printing, a black solid image was printed every 500 sheets, and streaks on the image were checked. The number of printed sheets until streaks were visually observed on the image was taken as the number of sheets on which streaks occurred due to the toner fusing and adhering to the development roll, and durability was evaluated. The results are shown in Table 4. The greater the number of printed sheets, the better the durability of the toner. The number of printed sheets is preferably 3,000 sheets or more, more preferably 4,000 sheets or more, and even more preferably 5,000 sheets or more.

[0108] Test Example 2 [Charging property under high temperature and high humidity (HH) conditions] The toner was mounted on a "MICROLINE 3010" (manufactured by OKI Data Corporation, fixing: contact fixing method, development: non-magnetic single-component development method), and 500 images were obtained under high temperature and high humidity conditions of 35°C and 85% relative humidity. The image density of the 50th and 500th images was measured using a transmission Macbeth densitometer "TR-927," and the chargeability under high temperature and high humidity was evaluated from the image density ratio (image density value of the 500th sheet / image density of the 50th sheet). The results are shown in Table 4. The larger the ratio value, the better the stability of the image density under high temperature and high humidity, and the higher the chargeability under high temperature and high humidity. The ratio value is preferably 0.75 or more, more preferably 0.85 or more, and even more preferably 0.95 or more.

[0109] [Table 4]

[0110] From the above results, it is apparent that all of Examples 1 to 9 have good electrostatic properties and durability under high temperature and high humidity conditions. In contrast, in Comparative Example 1, which used a crystalline polyester resin that was not a block polymer, and Comparative Example 2, which used a crystalline block polymer in which the crystalline polyester segment was not a ring-opening polymer of a cyclic lactone, both the electrostatic charge and durability under high temperature and high humidity conditions were insufficient. [Industrial Applicability]

[0111] The toner for developing electrostatic images of the present invention is suitably used for developing latent images formed in electrostatic image developing methods, electrostatic recording methods, electrostatic printing methods and the like.

Claims

1. A toner for developing electrostatic images, comprising a binder resin containing an amorphous polyester resin and a crystalline polyester resin, wherein the crystalline polyester resin contains a crystalline block polymer (C) in which an amorphous polyester segment (a) and a crystalline polyester segment (c) formed by ring-opening polymerization of a cyclic lactone are bonded via an ester bond.

2. 2. The toner for developing electrostatic images according to claim 1, wherein the total content of the amorphous polyester resin and the crystalline polyester resin in the binder resin is 80% by mass or more and 100% by mass or less.

3. 2. The toner for developing electrostatic images according to claim 1, wherein the mass ratio of the amorphous polyester segment (a) to the crystalline polyester segment (c) in the crystalline block polymer (C) is 2 / 98 or more and 40 / 60 or less.

4. 2. The toner for developing electrostatic images according to claim 1, wherein the cyclic lactone is ε-caprolactone.

5. 2. The toner for developing electrostatic images according to claim 1, wherein the mass ratio of the amorphous polyester resin to the crystalline block polymer (C) is 70 / 30 or more and 98 / 2 or less.