Binder resin composition for toner

Abstract

To provide a binder resin composition for a toner which is excellent in low temperature fixability, storage property and durability under high temperature and high humidity, and a toner for electrostatic charge image development containing the binder resin composition.SOLUTION: There are provided a binder resin composition for a toner that contains an amorphous block polymer (A) in which an amorphous polyester segment (a) and a crystalline polyester segment (c) formed by ring opening polymerization of cyclic lactone are coupled to each other through an ester bond, an amorphous polyester resin (B), and a crystalline polyester resin (C), wherein a mass ratio (amorphous polyester segment (a) / crystalline polyester resin (C)) of the amorphous polyester segment (a) to the crystalline polyester resin (C) is 40 / 60 to 70 / 30, and a content of the amorphous block polymer (A) is 2 mass% or more and 20 mass% or less; and a toner for electrostatic charge image development containing the binder resin composition.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a binder resin composition for a toner used for developing a latent image formed in, for example, an electrophotographic method, an electrostatic recording method, an electrostatic printing method, etc., and a toner for developing an electrostatic image containing the binder resin composition. [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 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.

[0004] Patent Document 3 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 recipient, and a fixing step of pressurizing and fixing the toner image transferred to the surface of the 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]

[0005] [Patent Document 1] JP 2011-53657 A [Patent Document 2] JP 2013-80052 A [Patent Document 3] JP 2007-114635 A Summary of the Invention [Problem to be solved by the invention]

[0006] 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.

[0007] However, although the low-temperature fixability is improved by the crystalline polyester resin, it is difficult to achieve compatibility with storage stability because the crystalline polyester plasticizes the amorphous polyester resin that serves as the matrix.

[0008] In order to achieve both fixability and storage stability, it is effective to microcrystallize the crystalline polyester resin in the toner, which also improves durability under high temperature and high humidity conditions.

[0009] Patent Documents 1 to 3 disclose polyester block polymers, but do not disclose their use in combination with crystalline polyester resins.

[0010] The present invention relates to a binder resin composition for toners, which is excellent in low-temperature fixing property, storage stability, and durability under high-temperature and high-humidity conditions, and to a toner for developing electrostatic images, which contains the binder resin composition. [Means for solving the problem]

[0011] The present invention relates to [1] A binder resin composition for toner, comprising an amorphous block polymer (A) 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, an amorphous polyester resin (B), and a crystalline polyester resin (C), in which the mass ratio of the amorphous polyester segment (a) to the crystalline polyester segment (c) (amorphous polyester segment (a) / crystalline polyester segment (c)) is 40 / 60 or more and 70 / 30 or less, and the content of the amorphous block polymer (A) is 2% by mass or more and 20% by mass or less; and [2] A toner for developing electrostatic images, comprising the binder resin composition for toners according to [1] above and a colorant. Regarding. Effect of the Invention

[0012] The toner binder resin composition of the present invention exerts excellent effects as a binder resin for toner in terms of low-temperature fixing property, storage stability, and durability under high-temperature and high-humidity conditions. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The binder resin composition for toner of the present invention contains an amorphous block polymer (A) 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, an amorphous polyester resin (B) and a crystalline polyester resin (C). Although the details of why the effects of the present invention are exhibited are not clear, it is presumed as follows.

[0014] Crystalline polyester resins are effective in improving low-temperature fixability, but because they plasticize the amorphous polyester resin that forms the matrix, it is difficult to achieve compatibility with storage stability. In order to achieve both fixability and storage stability, it is necessary to microcrystallize the crystalline polyester resin in the toner. In contrast, by blending an amorphous block polymer (A) in which a crystalline polyester segment (c) formed by ring-opening polymerization of a cyclic lactone is bonded to the end of an amorphous polyester segment (a) and the amorphous polyester segment (a) and the crystalline polyester segment (c) are in a predetermined ratio, it is possible to create a state in which the crystalline polyester segment (c) is finely dispersed in the amorphous polyester matrix. Furthermore, the crystalline polyester segment (c) acts as a crystal nucleating agent, which promotes the crystallization of the crystalline polyester resin (C) mixed with the amorphous block polymer (A), thereby realizing fine dispersion and high crystallization of the crystalline polyester resin (C). As a result, it is presumed that the low-temperature fixability is improved because the crystalline polyester resin (C) is melted from the starting point during fixing, and the storability is also improved because the crystalline polyester resin (C) is highly crystallized. Furthermore, it is considered that the durability of the toner is greatly improved because the amorphous block polymer (A) acts as a dispersant and the crystalline polyester resin (C) is finely dispersed in the amorphous polyester matrix, making it difficult to be exposed to the toner surface.

[0015] The binder resin composition for toner of the present invention contains an amorphous block polymer (A) 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.

[0016] The amorphous polyester segment (a) is formed by polycondensation of an alcohol component and a carboxylic acid component.

[0017] As the alcohol component, from the viewpoint of preservability, the alcohol component may be selected from the formula (I):

[0018] [ka]

[0019] (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.

[0020] The content of the alkylene oxide adduct of bisphenol A represented by formula (I) in the alcohol component is preferably 60 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%.

[0021] 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.

[0022] The carboxylic acid component is preferably at least one selected from the group consisting of aromatic dicarboxylic acid compounds, aliphatic dicarboxylic acid compounds, and trivalent or higher carboxylic acid compounds, and from the viewpoint of storage stability, it is more preferable that the composition contains an aromatic dicarboxylic acid compound.

[0023] 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.

[0024] From the viewpoint of low-temperature fixability, the content of the aromatic dicarboxylic acid compound in the carboxylic acid component is preferably 80 mol % or more, more preferably 90 mol % or more, even more preferably 95 mol % or more, and even more preferably 100 mol %.

[0025] 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 having 1 to 20 carbon atoms, adipic acid, and the like, anhydrides of these acids, and alkyl esters in which the alkyl group has 1 to 3 carbon atoms.

[0026] Examples of trivalent or higher carboxylic acid compounds include 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid, pyromellitic acid, anhydrides of these acids, and alkyl esters having an alkyl group with 1 to 3 carbon atoms.

[0027] The alcohol component may appropriately contain a monohydric alcohol, and the carboxylic acid component may appropriately contain a monovalent carboxylic acid compound.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] The crystalline polyester segment (c) is formed by ring-opening polymerization of a cyclic lactone.

[0032] 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 humidity conditions.

[0033] 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.

[0034] The mass ratio of the amorphous polyester segment (a) to the crystalline polyester segment (c) in the amorphous block polymer (A) (amorphous polyester segment (a) / crystalline polyester segment (c)) is 40 / 60 or more, preferably 43 / 57 or more, and more preferably 46 / 54 or more, from the viewpoint of storage stability, and is 70 / 30 or less, preferably 60 / 40 or less, and more preferably 55 / 45 or less, from the viewpoint of low-temperature fixability.

[0035] The glass transition temperature of the amorphous block polymer (A) is preferably −50° C. or higher, more preferably −40° C. or higher, and even more preferably −35° C. or higher from the viewpoint of storage stability, and is preferably 0° C. or lower, more preferably −10° C. or lower, and even more preferably −20° C. or lower from the viewpoint of low-temperature fixability. In the present invention, a block polymer is defined as an amorphous block polymer if no peak due to crystalline melting is observed between the glass transition temperature and 200° C. in the measurement of the glass transition temperature.

[0036] From the viewpoint of charging stability, the acid value of the amorphous block polymer (A) 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 13 mgKOH / g or less.

[0037] From the viewpoint of electrostatic stability, the hydroxyl value of the amorphous block polymer (A) is preferably 10 mgKOH / g or more, more preferably 20 mgKOH / g or more, and is preferably 80 mgKOH / g or less, more preferably 65 mgKOH / g or less.

[0038] The content of the amorphous block polymer (A) in the binder resin composition is 2 mass% or more, preferably 5 mass% or more, and 20 mass% or less, preferably 18 mass% or less, more preferably 13 mass% or less, and even more preferably 10 mass% or less.

[0039] The amorphous polyester resin (B) is preferably a polycondensate 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.

[0040] 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 %.

[0041] 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.

[0042] The aromatic dicarboxylic acid compound may be the same as those mentioned above, with terephthalic acid being preferred.

[0043] 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 75 mol % or less, even more preferably 70 mol % or less.

[0044] 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.

[0045] 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 having 1 to 20 carbon atoms, adipic acid, and the like; anhydrides of these acids; and alkyl esters in which the alkyl group has 1 to 3 carbon atoms.

[0046] The content of the aliphatic dicarboxylic acid compound in the carboxylic acid component is 0 mol% or more, preferably 3 mol% or more, more preferably 8 mol% or more, and preferably 25 mol% or less, more preferably 20 mol% or less, and even more preferably 15 mol% or less.

[0047] 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.

[0048] 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 15 mol % or more, more preferably 20 mol % or more, and is preferably 30 mol % or less, more preferably 25 mol % or less.

[0049] From the viewpoint of adjusting the molecular weight and softening point of the polyester resin, the alcohol component may appropriately contain a monohydric alcohol, and the carboxylic acid component may appropriately contain a monovalent carboxylic acid compound.

[0050] 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.

[0051] The amorphous polyester resin (B) can be produced by polycondensing an alcohol component and a carboxylic acid component in the same manner as in the production of the amorphous block polymer (A).

[0052] 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.

[0053] The softening point of the amorphous polyester resin (B) is preferably 120°C or higher, more preferably 125°C or higher, from the viewpoint of durability under high humidity conditions, 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.

[0054] 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, i.e., the value of [softening point / maximum endothermic peak temperature]. A 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.

[0055] The glass transition temperature of the amorphous polyester resin (B) 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 75°C or lower, more preferably 70°C or lower from the viewpoint of low-temperature fixability.

[0056] From the viewpoint of charging stability, the acid value of the amorphous polyester resin (B) 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.

[0057] From the viewpoint of charging stability, the hydroxyl value of the amorphous polyester resin (B) 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.

[0058] The content of the amorphous polyester resin (B) in the binder resin composition is preferably 70 mass % or more, more preferably 75 mass % or more, even more preferably 80 mass % or more, and preferably 95 mass % or less, more preferably 93 mass % or less, even more preferably 90 mass % or less.

[0059] The mass ratio of the amorphous block polymer (A) to the amorphous polyester resin (B) (amorphous block polymer (A) / amorphous polyester resin (B)) is preferably 2 / 98 or more, more preferably 5 / 95 or more, even more preferably 7 / 93 or more, and is preferably 20 / 80 or less, more preferably 15 / 85 or less, even more preferably 12 / 88 or less.

[0060] The total content of the amorphous block polymer (A) and the amorphous polyester resin (B) in the amorphous polyester resin is preferably 80 mass % or more, more preferably 90 mass % or more, even more preferably 95 mass % or more, and still more preferably 100 mass %.

[0061] The content of the amorphous polyester resin in the binder resin composition is preferably 80% by mass or more, more preferably 85% by mass or more, and preferably 98% by mass or less, more preferably 95% by mass or less, and even more preferably 92% by mass or less.

[0062] The crystalline polyester resin (C) is preferably a polycondensate of an alcohol component containing an aliphatic diol and a carboxylic acid component containing an aliphatic dicarboxylic acid compound.

[0063] Examples of the aliphatic diol include ethylene glycol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, and 1,12-dodecanediol.

[0064] From the viewpoint of achieving appropriate compatibility with the amorphous polyester, the aliphatic diol preferably has 6 or more carbon atoms and preferably has 12 or less carbon atoms, more preferably 10 or less carbon atoms.

[0065] From the viewpoint of improving the low-temperature fixing property of the toner, the aliphatic diol preferably has a hydroxyl group at the end of the carbon chain, and is more preferably an α,ω-straight-chain alkanediol.

[0066] The alcohol component may contain alcohol other than the aliphatic diol, but the content of the aliphatic diol in the alcohol component is preferably 70 mol % or more, more preferably 90 mol % or more, even more preferably 95 mol % or more, and even more preferably 100 mol %.

[0067] Examples of the alcohol component other than the aliphatic diol include aromatic diols such as alkylene oxide adducts of bisphenol A, and trihydric or higher alcohols such as glycerin.

[0068] The carboxylic acid component of the crystalline polyester resin (C) preferably contains an aliphatic dicarboxylic acid compound.

[0069] Examples of the aliphatic dicarboxylic acid compound include succinic acid (carbon number: 4), suberic acid (carbon number: 8), azelaic acid (carbon number: 9), sebacic acid (carbon number: 10), dodecanoic diacid (carbon number: 12), tetradecanoic diacid (carbon number: 14), succinic acid having an alkyl group or an alkenyl group in the side chain, anhydrides of these acids, and alkyl esters having 1 to 3 carbon atoms. In the present invention, the carboxylic acid compound includes not only free acids, but also anhydrides that decompose during the reaction to generate acids, and alkyl esters having 1 to 3 carbon atoms. However, the carbon number of the alkyl group of the alkyl ester portion is not included in the carbon number of the aliphatic dicarboxylic acid compound.

[0070] The chain hydrocarbon group in the aliphatic dicarboxylic acid compound may be linear or branched, and the number of carbon atoms in the aliphatic dicarboxylic acid compound is preferably 4 or more, more preferably 6 or more, and even more preferably 10 or more, from the viewpoint of appropriate compatibility with the amorphous polyester resin, and is preferably 14 or less, more preferably 13 or less.

[0071] The carboxylic acid component may contain a carboxylic acid compound other than an aliphatic dicarboxylic acid compound, but the content of the aliphatic dicarboxylic acid compound in the carboxylic acid component is preferably 80 mol % or more, more preferably 90 mol % or more, even more preferably 95 mol % or more, and even more preferably 100 mol %.

[0072] Other carboxylic acid compounds include aromatic dicarboxylic acid compounds such as terephthalic acid and isophthalic acid, and trivalent or higher carboxylic acid compounds such as trimellitic acid and pyromellitic acid.

[0073] The alcohol component may appropriately contain a monohydric alcohol, and the carboxylic acid component may appropriately contain a monovalent carboxylic acid compound.

[0074] The crystalline polyester resin (C) can be produced by polycondensing an alcohol and a carboxylic acid compound in the same manner as the amorphous polyester segment (a). The reaction temperature for polycondensation is preferably 120°C or higher, more preferably 180°C or higher, and preferably 230°C or lower, more preferably 220°C or lower.

[0075] The softening point of the crystalline polyester resin (C) is preferably 50°C or higher, more preferably 60°C or higher, and even more preferably 65°C or higher from the viewpoint of storage stability, and is preferably 100°C or lower, and more preferably 90°C or lower from the viewpoint of low-temperature fixability.

[0076] The melting point of the crystalline polyester resin (C) is preferably 50°C or higher, more preferably 60°C or higher, and even more preferably 65°C or higher from the viewpoint of storage stability, and is preferably 100°C or lower, and more preferably 90°C or lower from the viewpoint of low-temperature fixability.

[0077] From the viewpoint of charging stability, the acid value of the crystalline polyester resin (C) is preferably 2 mgKOH / g or more, more preferably 5 mgKOH / g or more, and preferably 30 mgKOH / g or less, more preferably 25 mgKOH / g or less.

[0078] From the viewpoint of electrostatic stability, the hydroxyl value of the crystalline polyester resin (C) is preferably 1 mgKOH / g or more, more preferably 2 mgKOH / g or more, and is preferably 50 mgKOH / g or less, more preferably 40 mgKOH / g or less.

[0079] The mass ratio of the amorphous block polymer (A) to the crystalline polyester resin (C) (amorphous block polymer (A) / crystalline polyester resin (C)) is preferably 20 / 80 or more, more preferably 30 / 70 or more, and even more preferably 40 / 60 or more from the viewpoint of storage stability, and is preferably 80 / 20 or less, more preferably 70 / 30 or less, and even more preferably 60 / 40 or less from the viewpoint of low-temperature fixability.

[0080] The content of the crystalline polyester resin (C) in the binder resin composition 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 20 mass% or less, even more preferably 15 mass% or less.

[0081] The binder resin composition may contain resins other than the amorphous block polymer (A), the amorphous polyester resin (B), and the crystalline polyester resin (C) within a range that does not impair the effects of the present invention. Examples of other resins include vinyl resins such as styrene-acrylic resins, epoxy resins, polycarbonates, polyurethanes, and composite resins containing two or more of these resins.

[0082] The total content of the amorphous block polymer (A), the amorphous polyester resin (B) and the crystalline polyester resin (C) in the binder resin composition is preferably 80 mass % or more, more preferably 90 mass % or more, even more preferably 95 mass % or more, and still more preferably 98 mass % or more, and is 100 mass % or less.

[0083] Further, the present invention provides a toner containing the binder resin composition for toner of the present invention as a binder resin, specifically, a toner for developing electrostatic images containing the binder resin composition for toner of the present invention and a colorant.

[0084] The content of the binder resin composition 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.

[0085] 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.

[0086] 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.

[0087] The toner for developing electrostatic images of the present invention may contain additives such as 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 composition and the colorant.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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.).

[0093] 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.

[0094] 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.

[0095] The toner for developing electrostatic images of the present invention is obtained by a method including a step of melt-kneading a mixture containing the amorphous block polymer (A), the amorphous polyester resin (B), the crystalline polyester resin (C), and a colorant, and further, if necessary, additives such as a release agent and a charge control agent (melt-kneading step).

[0096] The mixture to be melt-kneaded may be kneaded all at once or in portions, but it is preferable to mix the mixture in advance in a mixer such as a Henschel mixer or a ball mill and then supply the mixture to the kneader.

[0097] 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.

[0098] The melt-kneading temperature is not particularly limited as long as the resin is melted and mixed at the temperature.

[0099] 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.

[0100] 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.

[0101] Examples of hydrophobic treatment agents for hydrophobizing the surfaces of silica particles include hexamethyldisilazane (HMDS), dimethyldichlorosilane (DMDS), silicone oil, octyltriethoxysilane (OTES), and methyltriethoxysilane.

[0102] 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.

[0103] A mixer such as a Henschel mixer can be used to mix the toner particles and the external additives.

[0104] 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.

[0105] 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.

[0106] 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

[0107] 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.

[0108] [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.

[0109] [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.

[0110] [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.

[0111] [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.

[0112] [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.

[0113] [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.

[0114] [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.

[0115] [Volume Median Particle Size of Toner] Measuring device: Coulter Multisizer II (manufactured by Beckman Coulter, Inc.) Aperture diameter: 50μm Analysis software: Coulter Multisizer AccuComp version 1.19 (Beckman Coulter, Inc.) Electrolyte: Isoton II (Beckman Coulter, Inc.) Dispersion liquid: Emulgen 109P (Kao Corporation, polyoxyethylene lauryl ether, 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 the 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 so that the particle size of 30,000 particles could be measured in 20 seconds. 30,000 particles were measured, and the volume median particle size (D 50 ) is required.

[0116] Resin manufacturing example 1 The alcohol components and carboxylic acid components other than trimellitic anhydride shown in Table 1, and the 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 to 230°C in a mantle heater in a nitrogen atmosphere and reacted for 8 hours. Then, trimellitic anhydride was added, and the reaction was carried out at 220°C and 8.0 kPa to synthesize an amorphous polyester segment. Then, ε-caprolactone was added at 120°C and reacted for 2 hours, and then reacted for 1 hour at 8.0 kPa to obtain block polymers A1 to A7. The physical properties of the obtained block polymers are shown in Table 1. Note that, since no peak due to crystal melting was observed between the glass transition temperature and 200°C for all of the block polymers A1 to A5 and A7, they are amorphous block polymers.

[0117] [Table 1]

[0118] Resin manufacturing example 2 The alcohol components and carboxylic acid components other than trimellitic anhydride shown in Table 2, and the 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 to 230°C in a mantle heater in a nitrogen atmosphere and reacted for 8 hours. Thereafter, trimellitic anhydride was added and the reaction was carried out at 220°C and 8.0 kPa to obtain amorphous polyester resins (resins B1 to B3).

[0119] [Table 2]

[0120] Resin manufacturing example 3 The alcohol component and carboxylic acid component 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, an esterification catalyst was added, and the reaction was carried out at 8.0 kPa until the softening point shown in Table 3 was reached, obtaining crystalline polyester resins (resins C1 to C3).

[0121] [Table 3]

[0122] Examples 1 to 11 and Comparative Examples 1 to 4 As shown in Table 4, 100 parts by weight of binder resin, 5 parts by weight of colorant "ECB-301" (manufactured by Dainichi Seika Chemicals Co., Ltd., phthalocyanine blue), 1 part by weight of negative charge control agent "LR-147" (manufactured by Nippon Carlit Co., Ltd.), release agent ("Carnauba wax" Three parts by mass of "C1" (manufactured by Kato Yoko Co., Ltd., melting point: 80°C) were thoroughly stirred in 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 roll rotation speed was 200 r / min, the heating temperature setting inside the roll was 90°C, the temperature of the kneaded material was 140°C, the feed rate of the kneaded material was 10 kg / hour, and the average residence time was approximately 18 seconds. The kneaded material obtained was cooled from 140°C to 50°C in 1.5 hours, rolled and cooled with a cooling roller at 50°C, and then allowed to stand at 45°C for 4 hours, after which the volume median particle size (D 50 ) Toner particles of 5.5 μm were obtained. After standing, the volume median particle size (D 50 ) Toner particles of 5.5 μm were obtained.

[0123] To 100 parts by mass of the obtained toner particles, 1.5 parts by mass of "Aerosil R-972" (hydrophobic silica, manufactured by Nippon Aerosil Co., Ltd., hydrophobic treatment agent: DMDS, average particle size: 16 nm) and 1.0 part by mass of "RY-50" (hydrophobic silica, 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.

[0124] Test Example 1 [Low temperature fixability] The toner was mounted on a copy machine "AR-505" (manufactured by Sharp Corporation) whose fixing unit was modified to enable fixing outside the machine, and a printout was obtained in an unfixed state (print area: 2 cm × 12 cm, adhesion amount: 0.5 mg / cm 2 ). Then, using a fixing machine (fixing speed 300 mm / sec) adjusted to a total fixing pressure of 40 kgf, the temperature of the fixing roll was raised in steps of 5°C from 100°C to 240°C, and a fixing test was carried out on the unfixed print at each temperature. A cellophane adhesive tape "UNICEF Cellophane" (manufactured by Mitsubishi Pencil Co., Ltd., width: 18 mm, JIS Z 1522) was attached to the image portion of the obtained print, and after passing it through a fixing roller set at 30°C, the tape was peeled off. The paper used for printing was "CopyBond SF-70NA" (manufactured by Sharp Corporation, 75 g / m 2 ) was used. The optical reflection density before and after the tape was applied was measured using a reflection densitometer "RD-915" (manufactured by GretagMacbeth), and the temperature of the fixing roller at which the ratio of the two (after peeling / before application x 100) first exceeded 90% was determined as the minimum fixing temperature. The results are shown in Table 4. The lower the minimum fixing temperature, the better the low-temperature fixing ability.

[0125] Test Example 2 [Storage] 4 g of the toner was left for 72 hours in an environment of a temperature of 50° C. and a relative humidity of 85%. After leaving it, the degree of toner aggregation was visually observed, and the storage stability was evaluated according to the following evaluation criteria. The results are shown in Table 4.

[0126] [Evaluation Criteria] A: No aggregation was observed even after 48 and 72 hours. B: No aggregation is observed after 48 hours, but slight aggregation is observed after 72 hours. C: No aggregation is observed after 48 hours, but aggregation is clearly observed after 72 hours. D: Aggregation is already observed within 48 hours.

[0127] Test Example 3 [Durability under high temperature and high humidity conditions] The toner was loaded into 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 a diagonal stripe pattern with a blackening rate of 5.5% was continuously printed under 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 sheets printed 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 more sheets on which streaks occurred, i.e., the more sheets printed until streaks occurred, the better the durability of the toner. The number of sheets is preferably 5,000 sheets or more.

[0128] [Table 4]

[0129] From the above results, it is apparent that all of Examples 1 to 11 have good low-temperature fixability, storage stability, and durability under high-temperature and high-humidity conditions. In contrast, Comparative Example 1, which does not use an amorphous block polymer, is lacking in all of low-temperature fixability, storage stability, and durability. Comparative Example 2, which does not use a crystalline polyester resin, is lacking in low-temperature fixability and durability. Comparative Examples 3 and 4, in which the ratio of the amorphous polyester segment to the crystalline polyester segment in the amorphous block polymer is outside the specified range, are lacking in all of low-temperature fixability, storage stability, and durability. [Industrial Applicability]

[0130] The toner for developing electrostatic images containing the binder resin composition for toners 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. The binder resin composition for toner contains an amorphous block polymer (A) 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, an amorphous polyester resin (B), and a crystalline polyester resin (C), wherein the mass ratio of the amorphous polyester segment (a) to the crystalline polyester segment (c) (amorphous polyester segment (a) / crystalline polyester segment (c)) is 40 / 60 or more and 70 / 30 or less, and the content of the amorphous block polymer (A) is 2% by mass or more and 20% by mass or less.

2. 2. The binder resin composition for toner according to claim 1, wherein the total content of the amorphous block polymer (A), the amorphous polyester resin (B), and the crystalline polyester resin (C) is 80% by mass or more and 100% by mass or less.

3. 3. The binder resin composition for toner according to claim 1, wherein the cyclic lactone is ε-caprolactone.

4. 4. The binder resin composition for toner according to claim 1, wherein the content of the crystalline polyester resin (C) is from 2% by mass to 30% by mass.

5. 5. A toner for developing electrostatic images, comprising the binder resin composition for toners according to claim 1 and a colorant.

Images