Electrostatic charge image development toner

Abstract

To provide an electrostatic charge image development toner having high image density, excellent in hot offset resistance.SOLUTION: An electrostatic charge image development toner includes a binder resin and a coloring agent. The binder resin includes an amorphous polyester resin A of 25-75 mass%. The amorphous polyester resin A is a polycondensation product of a raw material monomer including an aromatic hydroxycarboxylic acid-based compound of 50-100 mol%.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an electrostatic charge image developing toner used for developing a latent image formed in an electrophotographic method, an electrostatic recording method, an electrostatic printing method, or the like.

Background Art

[0002] In recent years, with the increasing use of printers for industrial printing applications, the demand for an electrostatic charge image developing toner excellent in hot offset resistance and image density of printed matter has been increasing more and more.

[0003] On the other hand, from the viewpoints of low-temperature fixability and heat-resistant storage stability, Patent Document 1 describes a toner characterized by containing at least a binder resin and a release agent, wherein the binder resin contains a side-chain type liquid crystalline polyester resin having a liquid crystalline expression site with an aromatic hydroxycarboxylic acid as a basic skeleton in a side chain.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present invention relates to an electrostatic charge image developing toner having high image density and excellent hot offset resistance.

Means for Solving the Problems

[0006] The present invention relates to an electrostatic charge image developing toner containing a binder resin and a colorant, wherein the binder resin contains 25% by mass or more and 75% by mass or less of an amorphous polyester resin A, and the amorphous polyester resin A is a polycondensate of a raw material monomer containing 50 mol% or more and 100 mol% or less of an aromatic hydroxycarboxylic acid-based compound.

Effects of the Invention

[0007] The toner for electrostatic charge image development of the present invention exhibits excellent effects in improving image density and hot offset resistance.

Mode for Carrying Out the Invention

[0008] The toner for electrostatic charge image development of the present invention (hereinafter also simply referred to as "toner") contains a binder resin and a colorant, and the binder resin contains an amorphous polyester resin A obtained using a predetermined amount of an aromatic hydroxycarboxylic acid-based compound, which is a major feature. The reason why the toner of the present invention is effective in improving image density and hot offset resistance is not clear, but it is presumed as follows. Note that the following mechanism is a presumption and is not limited thereto.

[0009] The molecular chain of a conventional amorphous polyester resin formed by polycondensation of a diol and a dicarboxylic acid has alternating orientations of ester groups between monomers, that is, -CO-O- and -O-CO- are alternately arranged, and the intermolecular aromatic ring interaction is weak. Therefore, the elasticity at high temperature is low and the hot offset resistance is poor. In contrast, the molecular chain of an amorphous polyester resin formed by polycondensation of an aromatic hydroxycarboxylic acid-based compound has a unidirectional orientation of ester groups and the molecules are regularly arranged, and the aromatic ring interaction is strong. Therefore, the elasticity at high temperature is high and the hot offset resistance is improved. In addition, a conventional amorphous polyester resin has a weak aromatic ring interaction with a colorant, and the dispersibility of the colorant in the toner is poor, so the image density of a printed matter is low. An amorphous polyester resin using an aromatic hydroxycarboxylic acid-based compound has a strong aromatic ring interaction with a colorant, and the dispersibility of the colorant in the toner is good, so the image density of a printed matter becomes high.

[0010] The amorphous polyester resin A is a polycondensate of a raw material monomer containing an aromatic hydroxycarboxylic acid-based compound. The amorphous polyester resin A is preferably a resin having liquid crystallinity, which passes through a liquid crystal phase having a regular arrangement structure of molecular chains during melting in the transition from an amorphous phase to a crystalline phase.

[0011] Examples of the aromatic hydroxycarboxylic acid compounds include benzoic acid derivatives such as 3-hydroxybenzoic acid, 4-hydroxybenzoic acid, 2-hydroxybenzoic acid, 4-hydroxy-3-methoxybenzoic acid, and 4-hydroxy-3,5-dimethoxybenzoic acid; naphthoic acid derivatives such as 6-hydroxy-2-naphthoic acid, 1-hydroxy-2-naphthoic acid, and 3-hydroxy-2-naphthoic acid; phenylacetic acid derivatives such as 2-hydroxy-2-phenylacetic acid and hydroxydiphenylacetic acid; and acetylated products thereof.

[0012] From the viewpoint of hot offset resistance, the aromatic hydroxycarboxylic acid compound preferably contains 4-hydroxybenzoic acid. The content of 4-hydroxybenzoic acid in the aromatic hydroxycarboxylic acid compound is preferably 20 mol% or more, more preferably 30 mol% or more, still more preferably 40 mol% or more, and preferably 75 mol% or less, more preferably 65 mol% or less, still more preferably 55 mol% or less.

[0013] Also, from the viewpoint of increasing the image density, the aromatic hydroxycarboxylic acid compound preferably contains 3-hydroxybenzoic acid in which a hydroxyl group and a carboxyl group are arranged in the meta position. The content of 3-hydroxybenzoic acid in the aromatic hydroxycarboxylic acid compound is 0 mol% or more, preferably 4 mol% or more, more preferably 6 mol% or more, and preferably 30 mol% or less, more preferably 25 mol% or less, still more preferably 20 mol% or less.

[0014] The content of the aromatic hydroxycarboxylic acid compound is 50 mol% or more, preferably 60 mol% or more, more preferably 70 mol% or more, and 100 mol% or less, preferably 95 mol% or less, more preferably 90 mol% or less in the raw material monomers.

[0015] The raw material monomers other than the aromatic hydroxycarboxylic acid compound are preferably an alcohol component and a carboxylic acid component.

[0016] As the alcohol component, an aromatic diol is preferred.

[0017] Examples of the aromatic diol include hydroquinone, catechol, resorcinol, an alkylene oxide adduct of bisphenol A represented by the following formula (I), etc. Among these, hydroquinone is preferred.

[0018] The content of the alcohol component, preferably the aromatic diol, in the raw material monomers is 0 mol% or more, preferably 4 mol% or more, more preferably 6 mol% or more, and is preferably 20 mol% or less, more preferably 16 mol% or less, still more preferably 12 mol% or less.

[0019] As the carboxylic acid component, an aromatic dicarboxylic acid-based compound is preferred.

[0020] Examples of the aromatic dicarboxylic acid-based compound include phthalic acid, isophthalic acid, terephthalic acid, anhydrides of these acids, alkyl esters of these acids having 1 to 3 carbon atoms, etc.

[0021] The content of the carboxylic acid component, preferably the aromatic dicarboxylic acid-based compound, in the raw material monomers is 0 mol% or more, preferably 4 mol% or more, more preferably 6 mol% or more, and is preferably 20 mol% or less, more preferably 16 mol% or less, still more preferably 12 mol% or less.

[0022] The alcohol component may appropriately contain a monohydric alcohol, and the carboxylic acid component may appropriately contain a monohydric carboxylic acid-based compound.

[0023] In this specification, macromonomers and hydroxycarboxylic acids are not included in the alcohol component and the carboxylic acid component.

[0024] The equivalent ratio of the carboxyl group to the hydroxyl group (COOH group / OH group) in the raw material monomers of the amorphous polyester resin A is preferably 0.6 or more, more preferably 0.7 or more, still more preferably 0.8 or more, and preferably 1.3 or less, more preferably 1.2 or less, from the viewpoint of adjusting the softening point of the polyester resin and the like.

[0025] The amorphous polyester resin A preferably contains a structural unit derived from an aromatic hydroxycarboxylic acid-based compound in the main chain. When producing the amorphous polyester resin A, it is preferable to subject the raw material monomers to a polycondensation reaction at once. For example, the raw material monomers are in an inert gas atmosphere, preferably in the presence of an esterification catalyst, and further, if necessary, in the presence of a cocatalyst, a polymerization inhibitor, etc., preferably at a temperature of 120°C or more, more preferably 140°C or more, and preferably 270°C or less, more preferably 250°C or less, and polycondensed to produce an amorphous polyester resin containing a structural unit derived from an aromatic hydroxycarboxylic acid-based compound in the main chain.

[0026] Examples of the esterification catalyst include tin compounds such as dibutyltin oxide and tin(II) 2-ethylhexanoate, and titanium compounds such as titanium diisopropoxybis(triethanolamineate). The amount of the esterification catalyst used is preferably 0.01 part by mass or more, more preferably 0.1 part by mass or more, and preferably 1.5 parts by mass or less, more preferably 1 part by mass or less, based on 100 parts by mass of the raw material monomer (when the acetylating agent described below is used, based on 100 parts by mass of the total of the raw material monomer and the acetylating agent; the same applies hereinafter). Examples of the co-catalyst for the esterification catalyst include gallic acid and its hydrates. The amount of the co-catalyst used is preferably 0.001 part by mass or more, more preferably 0.01 part by mass or more, and preferably 0.5 part by mass or less, more preferably 0.1 part by mass or less, based on 100 parts by mass of the raw material monomer. Examples of the polymerization inhibitor include tert-butylcatechol. The amount of the polymerization inhibitor used is preferably 0.001 part by mass or more, more preferably 0.01 part by mass or more, and preferably 0.5 part by mass or less, more preferably 0.1 part by mass or less, based on 100 parts by mass of the raw material monomer.

[0027] In the present invention, from the viewpoint of low-temperature fixing property, the amorphous polyester resin A preferably has an acetyl group at its terminal. For this purpose, it is preferable to use an acetylated product of an aromatic hydroxycarboxylic acid-based compound, or to carry out the polycondensation reaction of the raw material monomers in the presence of an acetylating agent such as acetic anhydride or acetyl chloride to acetylate at least a part of the aromatic hydroxycarboxylic acid-based compound.

[0028] When having an acetyl group, the amount of the acetyl group in the amorphous polyester resin A can be adjusted by the amount of the acetylated product of the aromatic hydroxycarboxylic acid-based compound or the acetylating agent used. The molar ratio (CH3CO group / OH group) of the acetyl group to the hydroxyl group in the amorphous polyester resin A is preferably 50 / 50 or more, more preferably 70 / 30 or more, still more preferably 90 / 5 or more, and even more preferably 95 / 5 or more, and it is even more preferable that all the hydroxyl groups are acetylated. Incidentally, the amount of the acetyl group in the amorphous polyester resin A can be determined from the values of the acid value and the hydroxyl value.

[0029] In the present invention, the polyester resin may be a polyester resin modified to such an extent that its properties are not substantially impaired. Examples of the modified polyester resin include polyester resins grafted or blocked with phenol, urethane, epoxy, etc. by the methods described in JP-A-11-133668, JP-A-10-239903, JP-A-8-20636, etc. Among the modified polyester resins, a urethane-modified polyester resin obtained by extending the polyester resin with a polyisocyanate compound is preferable.

[0030] From the viewpoint of heat-resistant storage stability, the softening point of the amorphous polyester resin A is preferably 80°C or higher, more preferably 85°C or higher, still more preferably 90°C or higher, and from the viewpoint of low-temperature fixability, it is preferably 130°C or lower, more preferably 125°C or lower, still more preferably 100°C or lower.

[0031] Incidentally, the crystallinity of the resin is represented by the crystallinity index defined by the ratio of the softening point to the maximum peak temperature of endotherm measured by a differential scanning calorimeter, that is, the value of [softening point / maximum peak temperature of endotherm]. The amorphous resin is a resin in which no endothermic peak is observed, or when an endothermic peak is observed, the crystallinity index exceeds 1.4, preferably exceeds 1.5, more preferably is 1.6 or more, or is less than 0.6, preferably 0.5 or less. On the one hand, the crystalline resin has a crystallinity index of 0.6 or more, preferably 0.7 or more, more preferably 0.9 or more, and is a resin with a crystallinity index of 1.4 or less, preferably 1.2 or less, more preferably 1.1 or less. The crystallinity of the resin can be adjusted by the type and ratio of the raw material monomers, and the manufacturing conditions (for example, reaction temperature, reaction time, cooling rate), etc. The maximum peak temperature of endotherm refers to the temperature of the peak with the largest peak area among the observed endothermic peaks. In the crystalline resin, the maximum peak temperature of endotherm is taken as the melting point.

[0032] From the viewpoint of heat-resistant storage stability, the glass transition temperature of the amorphous polyester resin A is preferably 45°C or higher, more preferably 50°C or higher, still more preferably 55°C or higher, and from the viewpoint of low-temperature fixability, it is preferably 75°C or lower, more preferably 70°C or lower, still more preferably 65°C or lower.

[0033] From the viewpoint of hot offset resistance, the weight average molecular weight of the amorphous polyester resin A is preferably 1,000 or more, more preferably 1,300 or more, still more preferably 1,500 or more, and from the viewpoint of low-temperature fixability, it is preferably 4,000 or less, more preferably 3,000 or less, still more preferably 2,600 or less, still more preferably 2,200 or less.

[0034] The content of the amorphous polyester resin A is 25% by mass or more, preferably 35% by mass or more, more preferably 45% by mass or more in the binder resin, and from the viewpoint of durability, it is 75% by mass or less, preferably 65% by mass or less, more preferably 55% by mass or less.

[0035] Also, the content of the amorphous polyester resin A is preferably 20% by mass or more, more preferably 30% by mass or more, still more preferably 40% by mass or more in the toner particles, and from the viewpoint of durability, it is preferably 70% by mass or less, more preferably 60% by mass or less, still more preferably 50% by mass or less.

[0036] The binding resin preferably contains an amorphous polyester resin B which is a polycondensate of an alcohol component containing an alkylene oxide adduct of bisphenol A and a carboxylic acid component containing an aromatic dicarboxylic acid compound.

[0037] Examples of the alkylene oxide adduct of bisphenol A include the compound represented by the formula (I):

[0038]

Chemical formula

[0039] (In the formula, OR and RO are oxyalkylene groups, R is an ethylene group and / or a propylene group, x and y represent the average number of moles of alkylene oxide added, each is a positive number, the value of 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, still more preferably 4 or less) The compound represented by the formula (I) is preferred. Examples of the alkylene oxide adduct of bisphenol A represented by the formula (I) include polyoxypropylene adduct of 2,2-bis(4-hydroxyphenyl)propane, polyoxyethylene adduct of 2,2-bis(4-hydroxyphenyl)propane, etc. It is preferable to use one or more of these.

[0040] From the viewpoint of heat storage stability, the content of the alkylene oxide adduct of bisphenol A represented by the formula (I) in the alcohol component is preferably 70 mol% or more, more preferably 80 mol% or more, still more preferably 90 mol% or more, still more preferably 95 mol% or more, and still 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, neopentyl glycol; and polyhydric alcohols with three or more hydroxyl groups such as bisphenol A, hydrogenated bisphenol A, sorbitol, pentaerythritol, glycerin, trimethylolpropane, etc.

[0042] Examples of aromatic dicarboxylic acid compounds include phthalic acid, isophthalic acid, terephthalic acid, anhydrides of these acids, and alkyl esters of these acids with 1 to 3 carbon atoms.

[0043] From the perspective of heat-resistant storage stability, the content of the aromatic dicarboxylic acid compound in the carboxylic acid component is preferably 25 mol% or more, more preferably 30 mol% or more, still more preferably 35 mol% or more, and is 100 mol% or less.

[0044] Examples of other carboxylic acid components include aliphatic dicarboxylic acids such as fumaric acid, maleic acid, succinic acid, succinic acid derivatives substituted with hydrocarbon groups, glutaric acid, adipic acid, sebacic acid; polycarboxylic acids with three or more carboxyl groups such as trimellitic acid, pyromellitic acid; anhydrides of these acids; and alkyl esters of these acids with 1 to 3 carbon atoms.

[0045] The alcohol component may appropriately contain a monohydric alcohol, and the carboxylic acid component may appropriately contain a monohydric carboxylic acid compound.

[0046] From the perspective of adjusting the softening point of the polyester resin, the equivalent ratio of the carboxyl 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, still more preferably 0.8 or more, and is preferably 1.3 or less, more preferably 1.2 or less.

[0047] The polycondensation reaction conditions of the alcohol component and the carboxylic acid component of the amorphous polyester resin B are the same as those of the amorphous polyester resin A, except that the suitable reaction temperature is 160 °C or higher, more preferably 180 °C or higher, and 250 °C or lower, more preferably 240 °C or lower.

[0048] From the viewpoint of charge stability, the softening point of the amorphous polyester resin B is preferably 70 °C or higher, more preferably 90 °C or higher, still more preferably 100 °C or higher, and from the viewpoint of low-temperature fixability, it is preferably 170 °C or lower, more preferably 160 °C or lower, still more preferably 150 °C or lower.

[0049] Note that the amorphous polyester resin B may be composed of resins having different softening points from the viewpoints of low-temperature fixability and fixing width. The difference in the softening points of the two resins is preferably 10 °C or higher, more preferably 20 °C or higher, and preferably 60 °C or lower, more preferably 40 °C or lower.

[0050] From the viewpoint of the fixing width, the softening point of the amorphous polyester resin (resin BH) with the higher softening point is preferably 100 °C or higher, more preferably 110 °C or higher, still more preferably 120 °C or higher, and from the viewpoint of low-temperature fixability, it is preferably 170 °C or lower, more preferably 160 °C or lower, still more preferably 150 °C or lower.

[0051] From the viewpoint of charge stability, the softening point of the amorphous polyester resin (resin BL) with the lower softening point is preferably 70 °C or higher, more preferably 90 °C or higher, still more preferably 100 °C or higher, and from the viewpoint of low-temperature fixability, it is preferably 130 °C or lower, more preferably 125 °C or lower, still more preferably 120 °C or lower.

[0052] The mass ratio of resin BH to resin BL (resin BH / resin BL) is preferably 10 / 90 or higher, more preferably 20 / 80 or higher, still more preferably 30 / 70 or higher, and preferably 90 / 10 or lower, more preferably 80 / 20 or lower, still more preferably 75 / 25 or lower.

[0053] From the viewpoint of hot offset resistance, the weight average molecular weight of the amorphous polyester resin BH is preferably 60,000 or more, more preferably 80,000 or more, still more preferably 100,000 or more, and from the viewpoint of low temperature fixing property, it is preferably 250,000 or less, more preferably 200,000 or less, still more preferably 150,000 or less.

[0054] From the viewpoint of hot offset resistance, the weight average molecular weight of the amorphous polyester resin BL is preferably 4,000 or more, more preferably 4,500 or more, still more preferably 5,000 or more, and from the viewpoint of low temperature fixing property, it is preferably 7,000 or less, more preferably 6,500 or less, still more preferably 6,000 or less.

[0055] From the viewpoint of heat storage stability, the glass transition temperature of the amorphous polyester resin B is preferably 40°C or more, more preferably 50°C or more, and from the viewpoint of charge stability, it is preferably 80°C or less, more preferably 70°C or less.

[0056] In the binder resin, the content of the amorphous polyester resin B is preferably 25% by mass or more, more preferably 30% by mass or more, still more preferably 35% by mass or more, and preferably 75% by mass or less, more preferably 70% by mass or less, still more preferably 65% by mass or less.

[0057] Examples of other binder resins include amorphous polyester resins other than amorphous polyester resins A and B, crystalline polyester resins, vinyl resins such as styrene acrylic resins, epoxy resins, polycarbonates, polyurethanes, and composite resins containing two or more of these resins.

[0058] In the toner, the content of the binder resin is preferably 60% by mass or more, more preferably 70% by mass or more, and preferably less than 100% by mass, more preferably 98% by mass or less, still more preferably 95% by mass or less.

[0059] As the colorant, dyes, pigments, magnetic materials, etc. that are used as colorants for toner can be used. For example, carbon black, copper phthalocyanine pigment, 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. In the present invention, since the aromatic ring interaction with the amorphous polyester resin A is strong and the effect of enhancing the image density is more remarkable, a colorant having an aromatic ring is preferable, and a copper phthalocyanine pigment is more preferable.

[0060] 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, still more preferably 10 parts by mass or less, based on 100 parts by mass of the binder resin.

[0061] Also, the content of the colorant with respect to 100 parts by mass of the amorphous polyester resin A is preferably 5 parts by mass or more, more preferably 8 parts by mass or more, and preferably 20 parts by mass or less, more preferably 15 parts by mass or less.

[0062] In addition to the binder resin and the colorant, the toner of the present invention may contain additives such as a release agent, a charge control agent, magnetic powder, a fluidity improver, a conductivity adjuster, a reinforcing filler such as a fibrous substance, an antioxidant, and a cleaning property improver.

[0063] Examples of the release agent include hydrocarbon waxes such as polypropylene wax, polyethylene wax, ethylene-propylene copolymer wax, microcrystalline wax, paraffin wax, and Fischer-Tropsch wax, and their oxides; ester waxes such as carnauba wax, montan wax, and their deacidified waxes, and fatty acid ester waxes; fatty acid amides, fatty acids, higher alcohols, and fatty acid metal salts. These can be used alone or in combination of two or more.

[0064] From the viewpoint of the transferability of the toner, the melting point of the release agent is preferably 60°C or higher, more preferably 70°C or higher. From the viewpoint of low-temperature fixability, it is preferably 160°C or lower, more preferably 140°C or lower, still more preferably 120°C or lower, and even more preferably 110°C or lower.

[0065] From the viewpoints of the low-temperature fixability and offset resistance of the toner and the dispersibility in the binder resin, the content of the release agent is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, still more preferably 1.5 parts by mass or more, based on 100 parts by mass of the binder resin, and is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, still more preferably 7 parts by mass or less.

[0066] The charge control agent is not particularly limited, and may contain either a positive-chargeable charge control agent or a negative-chargeable charge control agent.

[0067] Examples of positive charge control agents 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", "Bontron N-11" (manufactured by Orient Chemical Industries, Ltd.), etc.; triphenylmethane dyes containing a tertiary amine as a side chain; quaternary ammonium salt compounds such as "Bontron P-51" (manufactured by Orient Chemical Industries, Ltd.), cetyltrimethylammonium bromide, "COPY CHARGE PX VP435" (manufactured by Clariant), etc.; polyamine resins such as "AFP-B" (manufactured by Orient Chemical Industries, Ltd.), etc.; imidazole derivatives such as "PLZ-2001", "PLZ-8001" (manufactured by Shikoku Kasei Kogyo Co., Ltd.), etc.; styrene-acrylic resins such as "FCA-701PT", "FCA-201-PS" (manufactured by Fujikura Kasei Co., Ltd.), etc.

[0068] Examples of negative charge control agents include metal-containing azo dyes such as "Valifast Black 3804", "Bontron S-31", "Bontron S-32", "Bontron S-34", "Bontron S-36" (manufactured by Orient Chemical Industries, Ltd.), "Eisenspirone Black TRH", "T-77" (manufactured by Hodogaya Chemical Co., Ltd.), etc.; metal compounds of benzoic acid compounds such as "LR-147", "LR-297" (manufactured by Nippon Carlit Co., Ltd.), etc.; metal compounds of salicylic acid compounds such as "Bontron E-81", "Bontron E-84", "Bontron E-88", "Bontron E-304" (manufactured by Orient Chemical Industries, Ltd.), "TN-105" (manufactured by Hodogaya Chemical Co., Ltd.), etc.; copper phthalocyanine dyes; quaternary ammonium salts such as "COPY CHARGE NX VP434" (manufactured by Clariant), nitroimidazole derivatives, etc.; organometallic compounds, etc.

[0069] From the viewpoint of the charge stability of the toner, the content of the charge control agent is preferably 0.01 part by mass or more, more preferably 0.2 part by mass or more, and preferably 10 parts by mass or less, more preferably 5 parts by mass or less, still more preferably 3 parts by mass or less, and still more preferably 2 parts by mass or less with respect to 100 parts by mass of the binder resin.

[0070] The toner of the present invention may be a toner obtained by any known method such as a melt-kneading method, an emulsion aggregation method, or a polymerization method. From the viewpoints of productivity and dispersibility of the colorant, a pulverized toner by a melt-kneading method is preferable. In the case of a pulverized toner by a melt-kneading method, for example, raw materials such as a binder resin, a colorant, a release agent, and a charge control agent are uniformly mixed with a mixer such as a Henschel mixer, and then melt-kneaded with a closed kneader, a single-screw or twin-screw extruder, an open roll type kneader, etc., and can be manufactured by cooling, pulverizing, and classifying.

[0071] In order to improve the transferability of the toner of the present invention, it is preferable to use an external additive. Examples of the external additive include inorganic fine particles such as silica, alumina, titania, zirconia, tin oxide, and zinc oxide, and organic fine 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 the transferability of the toner, hydrophobic silica subjected to a hydrophobization treatment is more preferable.

[0072] Examples of the hydrophobization treatment agent for hydrophobizing the surface of silica particles include hexamethyldisilazane (HMDS), dimethyldichlorosilane (DMDS), cyclic silazane, silicone oil, aminosilane, octyltriethoxysilane (OTES), and methyltriethoxysilane.

[0073] From the viewpoints of the chargeability, fluidity, and transferability of the toner, the average particle diameter of the external additive is preferably 10 nm or more, more preferably 15 nm or more, and preferably 250 nm or less, more preferably 200 nm or less, still more preferably 90 nm or less.

[0074] The external addition treatment by mixing toner particles and an external additive can be carried out according to a conventional method, and a mixer such as a Henschel mixer can be used.

[0075] From the viewpoints of the 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, still more preferably 0.3 parts by mass or more, and preferably 5 parts by mass or less, more preferably 3 parts by mass or less, based on 100 parts by mass of the toner particles before being treated with the external additive.

[0076] The volume median diameter (D 50 ) of the toner of the present invention is preferably 3 μm or more, more preferably 4 μm or more, and preferably 15 μm or less, more preferably 10 μm or less. In the present specification, the volume median diameter (D 50 ) means the particle diameter at which the cumulative volume frequency calculated by the volume fraction becomes 50% when calculated from the smaller particle diameter. Further, when the toner is treated with an external additive, the volume median diameter of the toner particles before being treated with the external additive is defined as the volume median diameter of the toner.

[0077] The toner of the present invention can be used as a one-component developer toner as it is, or as a two-component developer toner mixed with a carrier, in an image forming apparatus using a one-component development method or a two-component development method, respectively.

Examples

[0078] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited by these examples. The physical properties of resins and the like can be measured by the following methods.

[0079] 〔Softening point of resin〕 Using a flow tester "CFT-500D" (manufactured by Shimadzu Corporation), while heating a 1 g sample at a heating rate of 6 °C / min, apply a load of 1.96 MPa to the plunger and extrude it from a nozzle with a diameter of 1 mm and a length of 1 mm. Plot the plunger descent amount of the flow tester against the temperature, and take the temperature at which half of the sample has flowed out as the softening point.

[0080] [Maximum peak temperature of resin endotherm] Using a differential scanning calorimeter "Q-100" (manufactured by TA Instruments Japan Co., Ltd.), weigh 0.01 - 0.02 g of the sample into an aluminum pan, cool it from room temperature (25 °C) to 0 °C at a cooling rate of 10 °C / min, and maintain it at 0 °C for 1 minute. Then, measure it at a heating rate of 10 °C / min. Among the observed endothermic peaks, take the temperature of the peak with the largest peak area as the maximum peak temperature of endotherm.

[0081] [Glass transition temperature of resin] Using a differential scanning calorimeter "Q-100" (manufactured by TA Instruments Japan Co., Ltd.), weigh 0.01 - 0.02 g of the sample into an aluminum pan, heat it from room temperature (25 °C) to 200 °C at a heating rate of 10 °C / min, and then cool it from that temperature to 0 °C at a cooling rate of 10 °C / min. Next, heat the sample at a heating rate of 10 °C / min and measure the endothermic peak. Take the temperature of the intersection of the extension line of the baseline below the maximum peak temperature of endotherm and the tangent line showing the maximum slope from the rising part of the peak to the peak apex as the glass transition temperature.

[0082] [Weight average molecular weight (Mw) of resin] The molecular weight distribution is measured by gel permeation chromatography (GPC) method and the weight average molecular weight is determined by the following method. (1) Preparation of sample solution Dissolve the sample in a solvent (resin containing an aromatic hydroxycarboxylic acid compound: pentafluorophenol / chloroform = 1 / 2 (mass ratio), resin not containing an aromatic hydroxycarboxylic acid compound: tetrahydrofuran) at 40 °C so that the concentration becomes 0.5 g / 100 mL. Then, filter this solution using a PTFE type membrane filter "DISMIC-25JP" with a pore size of 0.20 μm (manufactured by Toyo Roshi Kaisha, Ltd.) to remove insoluble components and obtain a sample solution. (2) Molecular weight measurement Using the following measuring device and analytical column, flow an eluent (resin containing an aromatic hydroxycarboxylic acid: pentafluorophenol / chloroform = 1 / 2 (mass ratio), resin not containing an aromatic hydroxycarboxylic acid: tetrahydrofuran) at a flow rate of 1 mL per minute, and stabilize the column in a thermostat at 40 °C. Inject 100 μL of the sample solution there and perform the measurement. The molecular weight of the sample is calculated based on a calibration curve prepared in advance. For the calibration curve at this time, several types of monodisperse polystyrenes (A-500 (5.0×10 2 ), A-1000 (1.01×10 3 ), A-2500 (2.63×10 3 ), A-5000 (5.97×10 3 ), F-1 (1.02×10 4 ), F-2 (1.81×10 4 ), F-4 (3.97×10 4 ), F-10 (9.64×10 4 ), F-20 (1.90×10 5 ), F-40 (4.27×10 5 ), F-80 (7.06×10 5 ), F-128 (1.09×10 6 )) manufactured by Tosoh Corporation are used as standard samples. The values in parentheses indicate the molecular weights. Measuring device: HLC-8220GPC (manufactured by Tosoh Corporation) Analytical column: TSKgel GMH XL +TSKgel G3000H XL (manufactured by Tosoh Corporation)

[0083] 〔Melting point of the mold release agent〕 Using a differential scanning calorimeter "Q-100" (manufactured by TA Instruments Japan Co., Ltd.), 0.01 to 0.02 g of the sample is weighed into an aluminum pan, heated to 200 °C at a heating rate of 10 °C / min, and then cooled from that temperature to -10 °C at a cooling rate of 5 °C / min. Next, the sample is heated to 180 °C at a heating rate of 10 °C / min and measured. The maximum peak temperature of the endotherm observed from the melting endotherm curve obtained thereby is defined as the melting point of the mold release agent.

[0084] 〔Average particle diameter of the external additive〕 The average particle diameter refers to the number average particle diameter. The particle diameters (average value of the major axis and the minor axis) of 500 particles are measured from a scanning electron microscope (SEM) photograph, and the number average value thereof is taken.

[0085] 〔Volume median diameter (D 50 ) of the toner〕 · Measuring instrument: "Coulter Multisizer (registered trademark) III" (manufactured by Beckman Coulter, Inc.) · Aperture diameter: 50 μm · Analysis software: "Multisizer (registered trademark) III version 3.51" (manufactured by Beckman Coulter, Inc.) · Electrolyte: "Isoton (registered trademark) II" (manufactured by Beckman Coulter, Inc.) · Dispersion liquid: A solution prepared by dissolving polyoxyethylene lauryl ether "Emulgen (registered trademark) 109P" [manufactured by Kao Corporation, HLB (Griffin) = 13.6] in the electrolyte to adjust to 5% by mass. · Dispersion conditions: 10 mg of the measurement sample is added to 5 mL of the dispersion liquid, 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 further dispersed for 1 minute using the ultrasonic disperser to prepare a sample dispersion liquid. · Measurement conditions: The sample dispersion liquid is added to 100 mL of the electrolyte to adjust to a concentration at which the particle diameters of 30,000 particles can be measured in 20 seconds, then 30,000 particles are measured, and the volume median diameter (D 50 ) is determined from the particle size distribution.

[0086] Resin production example 1 The raw material monomers, acetylating agent, and esterification catalyst shown in Table 1 were placed in a 10-liter four-necked flask equipped with a thermometer, a stainless-steel stirring rod, a dehydrating tube, a cooling tube, and a nitrogen inlet tube, and heated in a mantle heater under a nitrogen atmosphere to 150°C over 1 hour. Then, after maintaining at 150°C for 30 minutes, the temperature was raised to 210°C and held at 210°C for 30 minutes. Then, the temperature was raised to 240°C over 1 hour, and the reaction was further carried out at 40 kPa until the desired softening point was reached to obtain an amorphous polyester resin (Resins A1 to A7).

[0087] [Table 1]

[0088] Resin Production Example 2 The raw material monomers and esterification catalyst shown in Table 2 were placed in a 10-liter four-necked flask equipped with a thermometer, a stainless-steel stirring rod, a dehydrating tube, a cooling tube, and a nitrogen inlet tube, and heated in a mantle heater under a nitrogen atmosphere to 235°C over 2 hours. Then, a polycondensation reaction was carried out at 235°C for 8 hours, and the reaction was further carried out at 8 kPa until the desired softening point was reached to obtain an amorphous polyester resin (Resin BL1).

[0089] Resin Production Example 3 The raw material monomers other than adipic acid and trimellitic anhydride shown in Table 2 and the esterification catalyst were placed in a 10-liter four-necked flask equipped with a thermometer, a stainless-steel stirring rod, a dehydrating tube, a cooling tube, and a nitrogen inlet tube, and heated in a mantle heater under a nitrogen atmosphere to 235°C over 2 hours. Then, after confirming that the reaction rate reached 95% or more at 235°C, it was cooled to 180°C. Then, the adipic acid and trimellitic anhydride shown in Table 2 were added, and the temperature was raised to 220°C over 2 hours. Then, after reacting at 220°C for 1 hour, the reaction was carried out at 8 kPa until the desired softening point was reached to obtain an amorphous polyester resin (Resin BH1). Here, the reaction rate refers to the value of (mol of generated reaction water volume / mol of theoretical generated water volume) × 100.

[0090]

Table 2

[0091] Examples 1 to 8 and Comparative Examples 1 to 3 100 parts by mass of a binder resin shown in Table 3, 5 parts by mass of copper phthalocyanine pigment "Pigment blue 15:3" (manufactured by Dainichi Seika Kogyo Co., Ltd.), 1 part by mass of a negative charge control agent "Bontron E-81" (manufactured by Orient Chemical Industries Co., Ltd.), and 2 parts by mass of a release agent "HNP-9" (manufactured by Nippon Seiro Co., Ltd., paraffin wax, melting point: 80°C) were thoroughly mixed with a Henschel mixer. Then, using a co-rotating twin-screw extruder with a total kneading length of 1560 mm, a screw diameter of 42 mm, and a barrel inner diameter of 43 mm, melt-kneading was performed at a roll rotation speed of 200 r / min and a heating temperature inside the roll of 100°C. The supply rate of the mixture was 20 kg / h, and the average residence time was about 18 seconds. The obtained melt-kneaded product was cooled and coarsely pulverized, then pulverized and classified with a jet mill to obtain toner particles with a volume median diameter (D 50 ) of 8 μm.

[0092] To 100 parts by mass of the obtained toner particles, 1 part by mass of hydrophobic silica "AEROSIL NAX 50" (manufactured by Nippon Aerosil Co., Ltd., hydrophobizing agent: HMDS, average particle diameter: about 30 nm) was added as an external additive and mixed with a Henschel mixer to obtain toner.

[0093] Test Example 1 [Hot Offset Resistance] The toner was mounted on a device obtained by improving the fixing device of a copying machine "AR-505" (manufactured by Sharp Corporation) so that fixing outside the device was possible, and a printed matter was obtained in an unfixed state (printing area: 2 cm × 12 cm, adhesion amount: 0.5 mg / cm 2)。After that, an external fixing device (fixing speed: 300 mm / sec) modified from "OKIMICROLINE3010" (manufactured by Okidata Corporation) was used, and the total fixing pressure was adjusted to 40 kgf. While sequentially increasing the temperature of the fixing roll from 100°C to 200°C in increments of 5°C, a fixing test was conducted on the unfixed printed matter at each temperature. The occurrence of hot offset was visually observed, and the temperature at which hot offset occurred was evaluated as the hot offset resistance. The results are shown in Table 3. The higher the temperature at which hot offset occurs, the more preferable it is.

[0094] Test Example 2 [Image Density] Using "Microline (registered trademark) 5400" (manufactured by Okidata Corporation), which was modified to be able to obtain an unfixed image, on high-quality paper "J paper A4 size" (manufactured by Fujifilm Business Innovation Corporation), a solid image with a toner adhesion amount on the paper of 0.42 - 0.48 mg / cm 2 was output to obtain an unfixed printed matter. Next, the temperature of an external fixing device (fixing speed: 300 mm / sec) modified from "OKIMICROLINE3010" (manufactured by Okidata Corporation) was set to 160°C, and the toner was fixed at a speed of 1.5 seconds per sheet in the A4 vertical direction to obtain a printed matter. The reflection image density of the fixed image portion of the output printed matter was measured using a colorimeter "SpectroEye" (manufactured by GretagMacbeth, light irradiation conditions: standard light source D50, observation field of view 2°, density standard DINNB, absolute white standard). The results are shown in Table 3. The larger the value of the reflection image density, the better the image density.

[0095]

Table 3

[0096] From the above results, it can be seen that compared with Comparative Examples 1 to 3, the toners of Examples 1 to 8 are excellent in hot offset resistance and have high image density. Further, from the comparison between Example 1 and Example 6, by including 3-hydroxybenzoic acid, which is the meta form, as the aromatic hydroxycarboxylic acid compound, and from the comparison between Example 1 and Example 8, by adjusting the amount of acetyl groups at the ends of the amorphous polyester resin, it can be seen that a higher effect is exerted on the image density.

Industrial Applicability

[0097] The toner for electrostatic charge image development of the present invention is suitably used for development of latent images formed in electrostatic charge image development methods, electrostatic recording methods, electrostatic printing methods, and the like.

Claims

1. An electrostatic charge image developing toner containing a binder resin and a colorant, wherein the binder resin contains 25% by mass or more and 75% by mass or less of an amorphous polyester resin A, and the amorphous polyester resin A is a polycondensate of raw material monomers containing 50 mol% or more and 100 mol% or less of an aromatic hydroxycarboxylic acid-based compound.

2. The electrostatic charge image developing toner according to claim 1, wherein in the amorphous polyester resin A, the main chain contains a structural unit derived from an aromatic hydroxycarboxylic acid-based compound.

3. The electrostatic charge image developing toner according to claim 1 or 2, wherein the amorphous polyester resin A has an acetyl group at the terminal.

4. The electrostatic charge image developing toner according to any one of claims 1 to 3, wherein the aromatic hydroxycarboxylic acid-based compound contains 4-hydroxybenzoic acid.

5. The electrostatic charge image developing toner according to any one of claims 1 to 4, wherein the aromatic hydroxycarboxylic acid-based compound contains 3-hydroxybenzoic acid.

6. The electrostatic charge image developing toner according to any one of claims 1 to 5, wherein the colorant contains a copper phthalocyanine pigment.

7. The electrostatic charge image developing toner according to any one of claims 1 to 6, which is a pulverized toner.

Images