Binder for image forming materials

Abstract

To provide a binder for image forming materials that satisfies heat resistance and pigment dispersibility while maintaining low-temperature fixability and hot offset resistance. [Solution] A binder for image forming materials containing a polyester resin (A) obtained by polycondensation of an alcohol component and a carboxylic acid component, and bisphenol A, wherein the binder contains 20 to 60 mol% of ethylene glycol based on the total number of moles of the alcohol component, and 70 to 90 mol% of terephthalic acid based on the total number of moles of the carboxylic acid component, and the solubility parameter (SP value) of the polyester resin (A) is 10.5 to 11.7 (cal / cm³). 3 ) 1 / 2 A binder for image forming materials, wherein the bisphenol A content is 1 to 100 ppm based on the weight of the binder for image forming materials.

Description

[Technical Field]

[0001] This invention relates to a binder for image forming materials. [Background technology]

[0002] In recent years, with the development of electrophotographic systems, the demand for electrophotographic devices such as photocopiers and laser printers has increased rapidly, and the requirements for their performance have also become more sophisticated. For full-color electrophotography, conventional methods and apparatus are known that involve forming a latent image based on color image information on a latent image carrier such as an electrophotographic photoreceptor, developing the latent image with a toner of the corresponding color, and then transferring the toner image onto a transfer material. After repeating this image formation process, the toner image on the transfer material is heated and fixed to obtain a multi-color image.

[0003] For these processes to proceed smoothly, the toner must first maintain a stable charge level, and then have good adhesion to the paper. Furthermore, since the device has a heating element in the fixing section, the temperature rises within the device, so the toner must not block within the device.

[0004] Furthermore, in addition to promoting miniaturization, increased speed, and higher image quality of electrophotographic equipment, there is a strong demand for improved low-temperature fixing properties of toner from an energy-saving perspective, specifically by reducing energy consumption in the fixing process. Furthermore, many types of paper are now used as transfer materials, including recycled paper with large surface irregularities and coated paper with a smooth surface. To accommodate the surface properties of these transfer materials, fusers with wide nip widths, such as soft rollers and belt rollers, are preferred. However, widening the nip width increases the contact area between the toner and the fuser roller, causing a phenomenon known as high-temperature offset, where molten toner adheres to the fuser roller. Therefore, resistance to offset is a prerequisite. In addition to the above, multi-color images (full color) require a much higher gloss than black and white images (monochrome) for purposes such as reproducing photographic images, and the toner layer of the resulting image must be smooth. Therefore, it is necessary to achieve high gloss while maintaining offset resistance and exhibiting low-temperature fixability, and there is a growing demand for high-gloss toner images across a wide working range.

[0005] Binders for image forming materials significantly affect the toner properties described above. While polystyrene resins, styrene-acrylic resins, polyester resins, epoxy resins, polyurethane resins, and polyamide resins are known, polyester resins have recently attracted particular attention due to their ease of balancing preservation and fixation properties.

[0006] As a method to broaden the fixing temperature range, a toner using a polyester resin containing an unsaturated carboxylic acid as a component has been proposed (Patent Document 1). However, while this method can prevent offset phenomena at high temperatures to some extent, the minimum fixing temperature is insufficient, and it still does not fully meet the demands for faster and more energy-efficient processes.

[0007] On the other hand, numerous toners using hybrid resins in which polyester and styrene-acrylic components are chemically bonded have been proposed (Patent Documents 2-6). However, while this method improves resistance to hot offset, electrostatic properties, and pulverization, its low-temperature fixation properties remain insufficient.

[0008] As described above, until now, there has been no binder for image forming materials that satisfies heat resistance and pigment dispersibility while maintaining low-temperature fixability and hot offset resistance. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-003985 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-286562 [Patent Document 3] Japanese Patent Application Laid-Open No. 2014-235362 [Patent Document 4] Japanese Patent Application Laid-Open No. 2008-009171 [Patent Document 5] Japanese Patent Application Laid-Open No. 2010-128466 [Patent Document 6] Japanese Patent Application Laid-Open No. 2006-047585 [Summary of the Invention] [Problems to be Solved by the Invention]

[0010] An object of the present invention is to provide a binder for an image forming material that satisfies heat storage stability and pigment dispersibility while maintaining low-temperature fixing properties and hot offset resistance. [Means for Solving the Problems]

[0011] As a result of intensive studies to solve these problems, the present inventors have reached the present invention. That is, the present invention is a binder for an image forming material containing a polyester resin (A) obtained by polycondensing an alcohol component and a carboxylic acid component and bisphenol A, wherein ethylene glycol is contained in an amount of 20 to 60 mol% based on the total number of moles of the alcohol component, and terephthalic acid is contained in an amount of 70 to 90 mol% based on the total number of moles of the carboxylic acid component, and the solubility parameter (SP value) of the polyester resin (A) is 10.5 to 11.7 (cal / cm 3 ) 1 / 2 and the content of bisphenol A is 1 to 100 ppm based on the weight of the binder for the image forming material. [Effects of the Invention]

[0012] According to the present invention, while maintaining low-temperature fixing properties and hot offset resistance, heat storage stability and pigments This makes it possible to provide a binder for image forming materials that satisfies the dispersibility requirements. [Modes for carrying out the invention]

[0013] The binder for image-forming materials of the present invention is a binder for image-forming materials containing a polyester resin (A) obtained by polycondensation of an alcohol component and a carboxylic acid component, and bisphenol A, wherein it contains 20 to 60 mol% of ethylene glycol based on the total number of moles of the alcohol component, and 70 to 90 mol% of terephthalic acid based on the total number of moles of the carboxylic acid component, and the solubility parameter (SP value) of the polyester resin (A) is 10.5 to 11.7 (cal / cm³). 3 ) 1 / 2 This is a binder for image forming materials in which the bisphenol A content is 1 to 100 ppm based on the weight of the binder for image forming materials. The binder for image forming materials of the present invention will be described below in order.

[0014] The binder for image-forming materials of the present invention contains a polyester resin (A) obtained by polycondensation of an alcohol component and a carboxylic acid component, and bisphenol A.

[0015] The polyester resin (A) may be either amorphous or crystalline polyester resin, with amorphous polyester resin being preferred from the viewpoint of pulverability. Furthermore, the polyester resin (A) may be either unsaturated or saturated polyester resin, with saturated polyester resin being preferred from the viewpoint of low-temperature fixability and pulverability. These may be a single type or a combination of two or more types. In this invention, "crystalline" means that, in the differential scanning calorimetry (also known as DSC measurement) described below, the DSC curve has a clear endothermic peak top temperature (Tm). "Amorphous" means that, when the transition temperature of a sample is measured using the differential scanning calorimeter described below, there is no endothermic peak top temperature. Measurements are taken using a differential scanning calorimeter (e.g., "DSC210" [manufactured by Seiko Instruments Inc.]). The crystalline resin is heated from 20°C to 150°C at a rate of 10°C / min for the first time, then cooled from 150°C to 0°C at a rate of 10°C / min, and then heated from 0°C to 150°C at a rate of 10°C / min for the second time. The temperature at which the endothermic peak peaks during the second heating process are shown is defined as the peak top temperature of the endothermic peak of the crystalline resin. Furthermore, in this invention, an unsaturated polyester resin refers to a polyester resin having a radical-reactive carbon-carbon double bond. On the other hand, a saturated polyester resin refers to a polyester resin that does not have a radical-reactive carbon-carbon double bond. The presence of aromatic rings or heterocyclic double bonds is not considered when determining whether a polyester resin is unsaturated or saturated.

[0016] Polyester resin (A) contains ethylene glycol as an alcohol component. The polyester resin (A) may contain an alcohol component (x) other than ethylene glycol. Examples of alcohol components (x) include monools (x1), diols other than ethylene glycol (x2), and polyols with a valency of 3 or higher (x3). These may be a single type or a combination of two or more types.

[0017] Examples of monools (x1) include linear or branched alkyl alcohols having 1 to 30 carbon atoms (methanol, ethanol, isopropanol, 1-decanol, dodecyl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, arachidyl alcohol, behenyl alcohol, and lignoceryl alcohol, etc.). Of these saturated monools, preferred from the viewpoint of image intensity and heat resistance for storage are linear or branched alkyl alcohols having 8 to 24 carbon atoms, more preferably linear alkyl alcohols having 8 to 24 carbon atoms, and even more preferably dodecyl alcohol, stearyl alcohol, arachidyl alcohol, behenyl alcohol, and lignoceryl alcohol.

[0018] Examples of diols (x2) include alkylene glycols with 3 to 36 carbon atoms (propylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, and 1,12-dodecanediol, etc.) (x22), and alkylene ether glycols with 4 to 36 carbon atoms (diethylene glycol, triethylene glycol, dipropylene glycol, polyethylene glycol) Examples include polypropylene glycol and polytetramethylene ether glycol (x23), alicyclic diols having 6 to 36 carbon atoms (such as 1,4-cyclohexanedimethanol and hydrogenated bisphenol A) (x24), (poly)alkylene oxide adducts of the above alicyclic diols (preferably with an average number of added moles of 1 to 30) (x25), aromatic diols [monocyclic divalent phenols (e.g., hydroquinone) and bisphenols] (x26), and alkylene oxide (hereinafter sometimes abbreviated as AO) adducts of the above aromatic diols (preferably with an average number of added moles of 2 to 30) (x27). Examples of the above AO adducts include ethylene oxide (hereinafter sometimes abbreviated as EO) adducts and propylene oxide (meaning "1,2-propylene oxide," hereinafter sometimes abbreviated as PO) adducts.

[0019] Alkylene oxide adducts, which are ethylene oxide adducts and propylene oxide adducts of bisphenols, are obtained by adding ethylene oxide or propylene oxide to bisphenols. Examples of bisphenols include those represented by the following general formula (1).

[0020] HO-Ar-P-Ar-OH (1) [In the formula, P represents an alkylene group having 1 to 3 carbon atoms, -SO2-, -O-, -S-, or a direct bond, and Ar represents a phenylene group in which a hydrogen atom may be substituted with a halogen atom or an alkyl group having 1 to 30 carbon atoms.]

[0021] Specific examples of bisphenols include, for example, bisphenol A, bisphenol F, bisphenol B, bisphenol AD, bisphenol S, trichlorobisphenol A, tetrachlorobisphenol A, dibromobisphenol F, 2-methylbisphenol A, 2,6-dimethylbisphenol A, and 2,2'-diethylbisphenol F, and two or more of these can be used in combination. Among the bisphenols, bisphenol A is preferred from the viewpoint of low-temperature fixability and heat resistance for storage.

[0022] From the viewpoint of low-temperature fixability and heat-resistant storage, the average number of moles of ethylene oxide adducts of aromatic diols and propylene oxide adducts of aromatic diols added is preferably 2 to 30 moles, more preferably 2 to 10 moles, even more preferably 2 to 5 moles, particularly preferably 2 to 4 moles, and most preferably 2 to 3 moles.

[0023] Of these diols (x2), from the viewpoint of low-temperature fixability and heat-resistant storage, alkylene glycols (x22) having 3 to 36 carbon atoms and alkylene oxide adducts (x27) of aromatic diols are preferred, more preferably alkylene oxide adducts of bisphenols, particularly preferably alkylene oxide adducts of bisphenol A, and most preferably ethylene oxide adducts and propylene oxide adducts of bisphenol A.

[0024] Examples of polyols with a valency of 3 or higher (x3) include aliphatic polyhydric alcohols with 3 to 36 carbon atoms and a valency of 3 or higher (x31), sugars and their derivatives (x32), AO adducts of aliphatic polyhydric alcohols (average number of added moles preferably 1 to 30) (x33), AO adducts of trisphenols (such as trisphenol PA) (average number of added moles preferably 2 to 30) (x34), and AO adducts of novolac resins (which include phenol novolac and cresol novolac, and have an average degree of polymerization preferably 3 to 60) (average number of added moles preferably 2 to 30) (x35).

[0025] Examples of aliphatic polyhydric alcohols (x31) with 3 to 36 carbon atoms and a valency of 3 or higher include alkane polyols and their intramolecular or intermolecular dehydrated products, such as glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, sorbitol, sorbitan, polyglycerin, and dipentaerythritol.

[0026] Examples of sugars and their derivatives (x32) include sucrose and methyl glucoside.

[0027] Among polyols with a valency of 3 or higher (x3), from the viewpoint of achieving both low-temperature fixability and resistance to hot offset, an AO adduct (average number of added moles is preferably 2 to 30) (x35) of an aliphatic polyhydric alcohol (x31) having 3 to 36 carbon atoms with a valency of 3 or higher and a novolac resin (which includes phenol novolac and cresol novolac, and the average degree of polymerization is preferably 3 to 60) is preferred.

[0028] As the alcohol component (x), a diol (x2) and a polyol (x3) with a valency of 3 or higher can be used in combination. When used in combination, the molar ratio of ethylene glycol and diol (x2) to polyol (x3) with a valency of 3 or higher [(EG+(x2)) / (x3)] is preferably 99 / 1 to 80 / 20, more preferably 98 / 2 to 85 / 15, and particularly preferably 97 / 3 to 90 / 10 from the viewpoint of low-temperature fixability and resistance to hot offset.

[0029] Polyester resin (A) contains terephthalic acid as its carboxylic acid component. The polyester resin (A) may also contain a carboxylic acid component (y) in addition to terephthalic acid. Examples of the carboxylic acid component (y) include aromatic carboxylic acids other than terephthalic acid (y1) and aliphatic carboxylic acids (y2). One type of carboxylic acid component (y) may be used, or two or more types may be used in combination.

[0030] Examples of aromatic carboxylic acids (y1) include aromatic dicarboxylic acids with 8 to 36 carbon atoms (phthalic acid, isophthalic acid, and naphthalenedicarboxylic acid, etc.) and aromatic polycarboxylic acids with 9 to 20 carbon atoms and a valency of 3 or higher (trimellitic acid and pyromellitic acid, etc.). Examples of aliphatic carboxylic acids (y2) include aliphatic dicarboxylic acids with 2 to 50 carbon atoms (oxalic acid, malonic acid, succinic acid, adipic acid, suberic acid, and sebacic acid, etc.), alicyclic dicarboxylic acids with 6 to 40 carbon atoms (dimeric acid (dimerized linoleic acid), etc.), and alkene dicarboxylic acids with 4 to 36 carbon atoms (alkenyl succinic acids such as dodecenyl succinic acid, maleic acid, fumaric acid, citraconic acid, and mesaconic acid, etc.).

[0031] As the carboxylic acid component (y), anhydrides of these carboxylic acids, lower alkyl (1-4 carbon atoms) esters (methyl esters, ethyl esters, isopropyl esters, etc.) may be used, or these carboxylic acids may be used in combination with other carboxylic acids.

[0032] Of these carboxylic acid components (y), preferred from the viewpoint of achieving both low-temperature fixability and resistance to hot offset are aromatic dicarboxylic acids having 8 to 36 carbon atoms, trivalent or higher aromatic polycarboxylic acids having 9 to 20 carbon atoms, aliphatic dicarboxylic acids having 2 to 50 carbon atoms, and alkene dicarboxylic acids having 4 to 36 carbon atoms. More preferably, these are aliphatic dicarboxylic acids having 4 to 10 carbon atoms, alkenyl succinic acid, phthalic acid, isophthalic acid, trimellitic acid, pyromellitic acid, and combinations thereof. Particularly preferred are adipic acid, phthalic acid, dodecenylsuccinic acid, trimellitic acid, and combinations thereof. Anhydrides and lower alkyl esters of these acids are equally preferred.

[0033] Polyester resin (A) may be polyester resins such as polyethylene terephthalate (hereinafter also referred to as PET) resin or their depolymers as raw materials. For example, recycled PET resin may be used, and PET resin recovered from the market (hereinafter referred to as recovered PET resin) may be used. Examples of recovered PET resin include PET bottles and PET films.

[0034] The total charging ratio of the alcohol component and carboxylic acid component of the polyester resin (A) is preferably 1 / 2 to 2 / 1, more preferably 1 / 1.3 to 1.5 / 1, and even more preferably 1 / 1.2 to 1.4 / 1, in terms of the equivalent ratio (molar ratio) of hydroxyl groups to carboxyl groups ([OH] / [COOH]), from the viewpoint of hot offset resistance.

[0035] The ethylene glycol content of the alcohol component of polyester resin (A) is 20 to 60 mol%, preferably 30 to 50 mol%, and more preferably 35 to 45 mol%, based on the total number of moles of alcohol components. If the ethylene glycol content is less than 20 mol%, the resistance to hot offset deteriorates, and if it exceeds 60 mol%, the low-temperature fixability deteriorates.

[0036] The alcohol content of the polyester resin (A), excluding ethylene glycol, is preferably 40 to 80 mol%, more preferably 50 to 70 mol%, and even more preferably 55 to 65 mol%, based on the total number of moles of alcohol components.

[0037] The terephthalic acid content of the carboxylic acid components in polyester resin (A) is 70 to 90 mol%, preferably 74 to 86 mol%, and more preferably 77 to 83 mol%, based on the total number of moles of carboxylic acid components. If the terephthalic acid content is less than 70 mol%, the heat resistance for storage deteriorates, and if it exceeds 90 mol%, the low-temperature fixability deteriorates.

[0038] In the polyester resin (A), the content of carboxylic acid components other than terephthalic acid is preferably 10 to 30 mol%, more preferably 14 to 26 mol%, and even more preferably 17 to 23 mol%, based on the total number of moles of carboxylic acid components.

[0039] The peak top molecular weight (Mp) of polyester resin (A) in gel permeation chromatography (GPC) is preferably 3,000 to 10,000, and more preferably 4,000 to 9,000, from the viewpoint of low-temperature fixability, hot offset resistance, and heat-resistant storage.

[0040] In the present invention, the peak-top molecular weight (Mp), number-average molecular weight (hereinafter sometimes abbreviated as Mn), and weight-average molecular weight (hereinafter sometimes abbreviated as Mw) of the polyester resin (A) can be measured using GPC under the following conditions. Equipment (example): HLC-8120 manufactured by Tosoh Corporation Column (example): TSK GEL GMH6 (2 pieces) [Manufactured by Tosoh Corporation] Measurement temperature: 40℃ Sample solution: 0.25% by weight THF solution Solution injection volume: 100μL Detection device: Refractive index detector Reference material: 12 samples of standard polystyrene (TSKstandard POLYSTYRENE) manufactured by Tosoh Corporation (molecular weights: 500, 1,050, 2,800, 5,970, 9,100, 18,100, 37,900, 96,400, 190,000, 355,000, 1,090,000, 2,890,000) To measure the molecular weight, the sample is dissolved in tetrahydrofuran (THF) to a concentration of 0.25% by weight, and the undissolved portion is filtered out using a glass filter to obtain the sample solution.

[0041] In the binder for an image forming material of the present invention, the glass transition temperature (Tg A ) of the polyester resin (A) is preferably 50 to 70 °C. When Tg A is 70 °C or lower, the low-temperature fixing property is good, and when it is 50 °C or higher, the heat-resistant storage property is good. The glass transition temperature (Tg A ) of the polyester resin (A) can be measured, for example, by the method (DSC method) specified in ASTM D3418-82 using DSC Q20 manufactured by TA Instruments Co., Ltd.

[0042] From the viewpoints of low-temperature fixing property and heat-resistant storage property, the acid value of the polyester resin (A) is preferably ˂15 mgKOH / g, more preferably 5 to 15 mgKOH / g, and still more preferably 8 to 12 mgKOH / g. When it is ˂15 mgKOH / g, the heat-resistant storage property and image quality stability are good. The acid value of the polyester resin (A) can be measured by the method specified in JIS K0070 (1992).

[0043] From the viewpoints of low-temperature fixing property and heat-resistant storage property, the hydroxyl value of the polyester resin (A) is preferably ˂60 mgKOH / g, more preferably 20 to 55 mgKOH / g, and still more preferably 30 to 50 mgKOH / g. The hydroxyl value of the polyester resin (A) can be measured by the method specified in JIS K0070 (1992).

[0044] The solubility parameter (SP value) of the polyester resin (A) is 10.5 to 11.7 (cal / cm 3 ) 1 / 2 and preferably 10.7 to 11.3, and more preferably 10.8 to 11.2. When the SP value of (A) is less than 10.5 (cal / cm 3 ) 1 / 2 , the hot offset resistance deteriorates, and when it exceeds 11.7 (cal / cm 3 ) 1 / 2 , the heat-resistant storage property deteriorates. The SP value in this invention is the value at 25°C calculated using the method described on pages 151-154 of Volume 14 of Polymer Engineering and Science by Robert F Fedors et al.

[0045] The flow softening point (°C) of polyester resin (A) is preferably 120°C or lower, more preferably 90°C to 120°C, even more preferably 90°C to 110°C, and particularly preferably 95°C to 105°C, from the viewpoint of low-temperature fixability. The flow softening point of polyester resin (A) can be adjusted by controlling the molecular weight and glass transition temperature of the polyester resin, and by changing the ratio of trivalent or higher constituent components to increase or decrease the number of crosslinking points. Specifically, the flow softening point can be increased by increasing the molecular weight and glass transition temperature (Tg) of the polyester resin. In addition, the flow softening point can be increased by increasing the number of crosslinking points.

[0046] The flow softening point (°C) of polyester resin (A) was measured under the following conditions. <Method for measuring the flow softening point> Using a constant-force extrusion type capillary rheometer flow tester [for example, Shimadzu Corporation, CFT-500D], a 1g sample is heated at a heating rate of 6°C / min while a load of 1.96 MPa is applied by a plunger, and the sample is extruded from a nozzle with a diameter of 1 mm and a length of 1 mm. A graph of "plunger descent (flow value)" and "temperature" is drawn, and the temperature corresponding to half of the maximum value of the plunger descent is read from the graph. This value (the temperature when half of the sample has flowed out) is defined as the flow softening point (°C).

[0047] In the binder for image-forming materials of the present invention, the polyester resin (A) can be manufactured in the same manner as known polyesters. For example, the reaction can be carried out by reacting the constituent components in an inert gas (such as nitrogen gas) atmosphere at a reaction temperature of preferably 150 to 280°C, more preferably 160 to 250°C, and even more preferably 170 to 235°C. The reaction time is preferably 30 minutes or more, more preferably 2 to 40 hours, from the viewpoint of ensuring a polycondensation reaction. Reducing the pressure is also effective in improving the reaction rate at the end of the reaction.

[0048] An esterification catalyst can be used as needed at this time. Examples of esterification catalysts include tin-containing catalysts (e.g., dibutyltin oxide), antimony trioxide, titanium-containing catalysts [e.g., titanium alkoxide, potassium titanate oxalate, titanium terephthalate, titanium alkoxide terephthalate, catalysts described in Japanese Patent Publication No. 2006-243715 {titanium diisopropoxybis(triethanolamine), titanium dihydroxybis(triethanolamine), titanium monohydroxytris(triethanolamine), titanylbis(triethanolamine) and their intramolecular polycondensates, etc.} and catalysts described in Japanese Patent Publication No. 2007-11307 (titanium tributoxyterephthalate, titanium triisopropoxyterephthalate and titanium diisopropoxyditeterephthalate, etc.)], zirconium-containing catalysts (e.g., zirconyl acetate), and zinc acetate. Among these, titanium-containing catalysts are preferred.

[0049] The binder for image forming materials of the present invention may further contain a polyester resin (B) other than polyester resin (A). The alcohol component and carboxylic acid component constituting the polyester resin other than polyester resin (A) are the same components as the alcohol component and carboxylic acid component listed as components of polyester resin (A).

[0050] Among the alcohol components, alkylene glycols having 3 to 36 carbon atoms (x22) and alkylene oxide adducts of aromatic diols (x27) are preferred from the viewpoint of low-temperature fixability and heat-resistant storage, alkylene oxide adducts of bisphenols (average number of added moles is preferably 2 to 30) are more preferred, alkylene oxide adducts of bisphenol A (average number of added moles is preferably 2 to 5) are even more preferred, and ethylene oxide adducts and / or propylene oxide adducts of bisphenol A (average number of added moles is preferably 2 to 3) are particularly preferred.

[0051] Among the carboxylic acid components, preferred from the viewpoint of achieving both low-temperature fixability and resistance to hot offset are aromatic dicarboxylic acids having 8 to 36 carbon atoms, trivalent or higher aromatic polycarboxylic acids having 9 to 20 carbon atoms, aliphatic dicarboxylic acids having 2 to 50 carbon atoms, and alkene dicarboxylic acids having 4 to 36 carbon atoms. More preferably, these are aliphatic dicarboxylic acids having 4 to 10 carbon atoms, alkenyl succinic acid, terephthalic acid, isophthalic acid, trimellitic acid, pyromellitic acid, and combinations thereof. Particularly preferred are adipic acid, dodecenylsuccinic acid, terephthalic acid, trimellitic acid, and combinations thereof. Anhydrides and lower alkyl esters of these acids are equally preferred.

[0052] The peak-top molecular weight (Mp) of polyester resin (B) in gel permeation chromatography (GPC) is preferably 1,000 to 100,000, from the viewpoint of low-temperature fixability, hot-offset resistance, and heat-resistant storage. The Mp, Mn, and Mw of polyester resin (B) can be measured under the same conditions as those for polyester resin (A).

[0053] From the viewpoint of resistance to hot offset, the flow softening point (°C) of polyester resin (B) is preferably 120°C to 160°C, more preferably 130°C to 155°C, and even more preferably 140°C to 150°C. The flow softening point of polyester resin (B) can be measured in the same way as the flow softening point of polyester resin (A), and the method for adjusting the flow softening point is also the same as for (A).

[0054] The acid value of the polyester resin (B) is preferably 40 mg KOH / g or less, more preferably 30 mg KOH / g or less, and even more preferably 5 to 30 mg KOH / g, from the viewpoint of low-temperature fixability and heat-resistant storage. The acid value of polyester resin (B) can be measured by the method specified in JIS K0070 (1992).

[0055] In the binder for image forming materials of the present invention, the glass transition temperature (Tg) of the polyester resin (B) is B The temperature is preferably between 50 and 70°C. Tg B If the temperature is 70°C or below, low-temperature fixing properties are good, and if it is 50°C or above, heat-resistant storage properties are good. Note that the glass transition temperature (Tg) of polyester resin (A) B This can be measured, for example, using a DSC Q20 manufactured by TA Instruments Co., Ltd., by the method specified in ASTM D3418-82 (DSC method).

[0056] In the binder for image forming materials of the present invention, when it contains polyester resin (B), the weight ratio of polyester resin (A) to polyester resin (B) [(A) / (B)] is preferably 50 / 50 to 90 / 10, from the viewpoint of achieving both low-temperature fixability, hot offset resistance, and heat-resistant storage.

[0057] From the viewpoint of compatibility, the binder for image-forming materials of the present invention preferably has an absolute difference of 1.3 (cal / cm²) between the SP value of polyester resin (A) and the SP value of polyester resin (B). 3 ) 1 / 2 The following applies:

[0058] In the binder for image-forming materials of the present invention, the polyester resin (B) can be manufactured in the same manner as known polyesters. An esterification catalyst can be used as needed. The same esterification catalyst as that used for polyester resin (A) can be used.

[0059] The binder for image-forming materials of the present invention may further contain a vinyl resin (C), and it is preferable that the vinyl resin (C) contains a polyfunctional vinyl monomer (a) as a monomer.

[0060] Examples of polyfunctional vinyl monomers (a) include divalent vinyl monomers and trivalent or higher vinyl monomers. These may be a single type or a combination of two or more types.

[0061] Examples of divalent vinyl monomers include divinylbenzene, 1,5-hexadiene, di(meth)acrylate of glycerin, di(meth)acrylate of trimethylolpropane, di(meth)acrylate of 3-hydroxy-1,5-pentanediol, and di(meth)acrylate of 2-hydroxy-2-ethyl-1,3-propanediol.

[0062] Examples of vinyl monomers with a valency of 3 or higher include trimethylolpropane tri(meth)acrylate, 1,3,5-benzenetricarboxylic acid triallyl, glycerin tri(meth)acrylate, pentaerythritol tri(meth)acrylate; and tri(meth)acrylate of the ethylene oxide adduct of trimethylolpropane, tetra(meth)acrylate of pentaerythritol, penta(meth)acrylate of dipentaerythritol and hexa(meth)acrylate of dipentaerythritol; tetra(meth)acrylate of the ethylene oxide adduct of dipentaerythritol, penta(meth)acrylate of the ethylene oxide adduct of dipentaerythritol, and penta(meth)acrylate of the propylene oxide adduct of dipentaerythritol.

[0063] Of these polyfunctional vinyl monomers (a), divinylbenzene and trimethylolpropane triacrylate are preferred in terms of low-temperature fixability, resistance to hot offset, and pulverability.

[0064] The vinyl resin (C) may contain a monomer other than the polyfunctional vinyl monomer (a) as a constituent monomer, from the viewpoint of the toner's hot offset resistance, heat storage resistance, pulverability, and electrostatic stability. The monomer (b) is preferably one that contains styrene monomers (b1), (meth)acrylic monomers (b2), vinyl ester monomers (b3), and monomers having a nitrile group (b4) as constituent monomers. Monomer (b) may be used alone or in combination of two or more types.

[0065] Examples of styrene monomers (b1) include styrene and alkylstyrenes with 1 to 3 carbon atoms in the alkyl group (e.g., α-methylstyrene and p-methylstyrene).

[0066] Examples of (meth)acrylic monomers (b2) include (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl (meth)acrylate, ethyl-2-(hydroxymethyl)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and lauryl (meth)acrylate.

[0067] Examples of vinyl ester monomers (b3) include vinyl acetate, vinyl propionate, and isopropenyl acetate.

[0068] An example of a monomer (b4) having a nitrile group is acrylonitrile.

[0069] Of these monomers (b), styrene, acrylic acid, butyl acrylate, ethyl acrylate, and acrylonitrile are preferred.

[0070] The weight percentage of polyfunctional vinyl monomer (a) in the monomers constituting the vinyl resin (C) is preferably 0.1 to 10% by weight, based on the total weight of the monomers, from the viewpoint of resistance to hot offsetting and pulverability.

[0071] The monomers constituting the vinyl resin (C) preferably further contain monomer (b), and from the viewpoint of hot offset resistance and pulverability, monomer (b) preferably accounts for 90 to 99.9% by weight based on the total weight of the monomers.

[0072] In the binder for image forming materials of the present invention, the glass transition temperature (Tg) of the vinyl resin (C) is C The temperature is preferably between -35 and 47°C. Tg C If the temperature is 47°C or below, the low-temperature fixing properties will be good, and if it is -35°C or above, the heat-resistant storage properties will be good. Note that the glass transition temperature (Tg) of vinyl resin (C) is... C ) is the Fox-Flory equation, 1 / Tg 12 This value is calculated by =φ(1) / Tg1 + φ(2) / Tg2. 12 φ(1) corresponds to the Tg of vinyl resin (C) in absolute temperature (unit K), Tg1 and Tg2 are the glass transition temperatures (unit K) of the homopolymers of the monomers constituting vinyl resin (C), and φ(2) are the weight percentages of the monomers constituting vinyl resin (C).

[0073] The glass transition temperature of the monomer homopolymer constituting vinyl resin (C) is calculated using Polymer Design Tools software (DTW Associates, Inc., version 1.1).

[0074] The acid value of the vinyl resin (C) is preferably 55 mg KOH / g or less from the viewpoint of low-temperature fixation. The acid value of vinyl resin (C) is calculated by using the acid value of each monomer used in the polymerization of vinyl resin (C) and the weight of each monomer, and then expressing the result as a weight percentage.

[0075] The vinyl resin (C) in the binder for image-forming materials of the present invention can be produced by polymerizing a monomer composition containing a polyfunctional vinyl monomer (a) and a monomer (b) used as needed, by a known method (such as the method described in Japanese Patent Application Publication No. 5-117330). For example, it can be synthesized by a solution polymerization method in which the monomer is reacted with a radical reaction initiator (such as azobisisobutyronitrile) in a solvent (such as toluene). Furthermore, in the above solution polymerization method, producing the vinyl resin (C) in the presence of the polyester resin (A) instead of the solvent is preferable from the viewpoint of achieving both pulverability and resistance to hot offset, as the vinyl resin (C) can be uniformly crosslinked within the polyester resin (A).

[0076] The radical initiator (c) is not particularly limited and includes inorganic peroxides (c1), organic peroxides (c2), and azo compounds (c3). These radical initiators may also be used in combination.

[0077] The inorganic peroxide (c1) is not particularly limited, but examples include hydrogen peroxide, ammonium persulfate, potassium persulfate, and sodium persulfate.

[0078] The organic peroxide (C2) is not particularly limited, but examples include benzoyl peroxide, di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, α,α-bis(t-butylperoxy)diisopropylbenzene, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, di-t-hexyl peroxide, 2,5-dimethyl-2,5-di-t-butylperoxyhexine-3, acetyl peroxide, isobutyryl peroxide, octaninol peroxide, and decanolyl peroxide. Examples include lauroyl peroxide, 3,3,5-trimethylhexanoyl peroxide, m-toluyl peroxide, t-butyl peroxyisobutyrate, t-butyl peroxyneodecanoate, cumyl peroxyneodecanoate, t-butyl peroxy-2-ethylhexanoate, t-butyl peroxy-3,5,5-trimethylhexanoate, t-butyl peroxylaurate, t-butyl peroxybenzoate, t-butyl peroxyisopropyl monocarbonate, and t-butyl peroxyacetate.

[0079] The azo compound (c3) is not particularly limited, but examples include 2,2'-azobis-(2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1,1'-azobis(cyclohexane-1-carbonitride), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, and azobisisobutyronitrile.

[0080] Among these, organic peroxides (C2) are preferred because they have high initiator efficiency and do not produce toxic by-products such as cyanide compounds, and t-butyl peroxy-2-ethylhexanoate and di-t-butyl peroxide are more preferred.

[0081] The binder for image-forming materials of the present invention, when it contains a vinyl resin (C), can be obtained by mixing a polyester resin (A) and a vinyl resin (C) using a method described later. However, producing the vinyl resin (C) in the presence of the polyester resin (A) is preferable from the viewpoint of achieving both pulverability and hot offset properties, as the vinyl resin (C) can be uniformly crosslinked within the polyester resin (A). The binder for image-forming materials of the present invention may also contain polyester resin (A), polyester resin other than polyester resin (B), resin other than vinyl resin (C), and known additives (such as mold release agents).

[0082] In the binder for image-forming materials of the present invention, the bisphenol A content is 1 to 100 ppm based on the weight of the binder for image-forming materials, preferably 10 to 90 ppm, and more preferably 20 to 80 ppm. If the bisphenol A content is less than 1 ppm, the pigment dispersibility deteriorates, and if it exceeds 100 ppm, the heat resistance and storage properties deteriorate. The bisphenol A content can be adjusted by the amount of bisphenol A added.

[0083] The bisphenol A content (by weight) in the binder for image-forming materials of the present invention can be measured by liquid chromatography (hereinafter abbreviated as LC) under the following conditions. LC measuring device: "ACQUITY UPLC H-Class" [Waters] Column: "CAPCEL PACK C18" (particle size: 5 μm, ID: 4.6 mmφ) (Length 250mm) [Made by SHISEIDO] Mobile phase: 0.05% phosphoric acid aqueous solution / methanol = 80 / 20 (volume %) Injection volume: 10μl Flow rate: 0.6ml / min Column temperature: 40℃ Detector: "PDA detector" [(manufactured by Shimadzu Corporation)] Detection wavelength: 230nm <Method for preparing sample solutions> 1) Place 0.2 g of image-forming material binder into a screw-top bottle and dissolve it with 1.0 g of tetrahydrofuran (THF). 2) After dissolution, add 10g of methanol to the screw bottle to precipitate any undissolved material. 3) Use a centrifuge to settle the insoluble components at 2000 rpm for 5 minutes. 4) The supernatant obtained in step 3) is filtered using a syringe and membrane filter to obtain the sample solution.

[0084] In image-forming material binders, the phosphorus content is preferably 10 to 400 ppm based on the weight of the binder, as measured by X-ray fluorescence. A phosphorus content of 10 ppm or more results in good pigment dispersibility, while a content of 400 ppm or less results in good heat resistance for storage. The phosphorus content can be adjusted by the amount of phosphorus-containing compound added.

[0085] In this specification, the quantitative determination of the phosphorus element content by fluorescent X-ray is described below. <Sample adjustment> A pressure molding method can be used to compress powders such as binders and toners for image forming materials into pellets. For example, a 5mm thick ring made of polyvinyl chloride resin can be filled with a powder sample in the center to form a slight mound, and then pressed with a press machine under a load of 10t to form pellets. Care must be taken to avoid contamination by other components, especially phosphorus. <Measurement Method> A calibration curve can be prepared using standard samples with known phosphorus concentrations, and the analytical value can be determined from the X-ray intensity of the analytical sample. Alternatively, if the majority of the resin composition is known, the approximate content can be determined using the fundamental parameter method (FP method). However, except in cases where the contents of toner, etc., are unknown, the FP method is relatively inaccurate, so it is preferable to use a calibration curve method that can measure the phosphorus concentration more accurately. <Measuring device> For example, it can be measured using an X-ray fluorescence analyzer (such as the Rigaku Supermini200).

[0086] The glass transition temperature (Tg) of the binder for image forming materials of the present invention is preferably 50 to 70°C. If the Tg of the binder for image forming materials is 70°C or lower, the low-temperature fixation performance is better, and if it is 50°C or higher, the heat resistance for storage is better. The glass transition temperature (Tg) is measured using the method specified in ASTM D3418-82 (DSC method) with a DSC Q20, for example, manufactured by TA Instruments Co., Ltd.

[0087] The acid value of the binder for image-forming materials of the present invention is preferably 10 to 30 mg KOH / g. The acid value of binders for image forming materials can be measured by the method specified in JIS K0070 (1992).

[0088] The binder for image-forming materials of the present invention may contain THF-insoluble components. The THF-insoluble content (by weight) in the binder for image forming materials of the present invention is preferably 50% by weight or less, and more preferably 5 to 30% by weight, from the viewpoint of achieving both resistance to hot offset and low-temperature fixing properties.

[0089] The content (by weight) of THF-insoluble components in the binder for image forming materials of the present invention was determined by the following method. Add 50 mL of THF to 0.5 g of the sample and stir under reflux for 3 hours. After cooling, filter off the insoluble components using a glass filter, and dry the resin on the glass filter under reduced pressure at 80°C for 3 hours. The weight of the dried resin on the glass filter is taken as the weight of the THF-insoluble components, and the weight of the THF-soluble components is obtained by subtracting the weight of the THF-insoluble components from the weight of the sample, and the weight percentages of the THF-insoluble and THF-soluble components are calculated.

[0090] A method for manufacturing binders for image forming materials will be described. The binder for image-forming materials is not particularly limited as long as it contains polyester resin (A) and bisphenol A. For example, when mixing the above-mentioned polyester resin (A), bisphenol A, polyester resin (B) if necessary, vinyl resin (C), and additives, the mixing method can be a generally known method, such as powder mixing, melt mixing, and solvent mixing. In addition, the polyester resin (A), bisphenol A, polyester resin (B) if necessary, vinyl resin (C), and additives may be mixed simultaneously when manufacturing the binder for image-forming materials. Among these methods, melt mixing, which provides uniform mixing and does not require solvent removal, is preferred.

[0091] Examples of mixing equipment for powder mixing include Henschel mixers, Nauter mixers, and Banbury mixers. A Henschel mixer is preferred. Mixing equipment for melt-mixing includes batch-type mixing equipment such as reaction vessels and continuous-type mixing equipment. Continuous-type mixing equipment is preferred for uniform mixing at the appropriate temperature in a short time. Examples of continuous-type mixing equipment include static mixers, extruders, continuous kneaders, and three-roll mixers.

[0092] Methods of solvent mixing include dissolving the above-mentioned polyester resin (A) or other resins in a solvent (ethyl acetate, THF, acetone, etc.), homogenizing them, then desolventing and pulverizing them, or dissolving the above-mentioned polyester resin (A) or other resins in a solvent (ethyl acetate, THF, acetone, etc.), dispersing them in water, then granulating and desolventing them.

[0093] The binder for image forming materials of the present invention can be used in toner.

[0094] In addition to the binder for image forming materials of the present invention, the toner may optionally contain one or more known additives selected from colorants, release agents, charge control agents, and fluidizing agents.

[0095] As a coloring agent, all dyes and pigments used as coloring agents for toners can be used. For example, carbon black, iron black, Sudan black SM, First Yellow G, benzidine yellow, pigment yellow, India First Orange, Irgasine red, paranitroaniline red, toluidine red, carmine FB, pigment orange R, lake red 2G, rhodamine FB, rhodamine B lake, methyl violet B lake, phthalocyanine blue, pigment blue, brilliant green, phthalocyanine green, oil yellow GG, kayaset YG, orazole brown B, and oil pink OP are examples. The coloring agent may be any one of these alone, or a mixture of two or more. In addition, if necessary, magnetic powder (powder of ferromagnetic metals such as iron, cobalt, and nickel, or compounds such as magnetite, hematite, and ferrite) may be included, also serving as a coloring agent.

[0096] Preferred release agents have a flow softening point (T1 / 2) of 50 to 170°C as measured by a flow tester. Examples include low molecular weight polypropylene, low molecular weight polyethylene, low molecular weight polypropylene polyethylene copolymer, polyolefin wax, microcrystalline wax, paraffin wax, aliphatic hydrocarbon waxes such as Fischer-Tropsch wax and their oxides, carnauba wax, montane wax, sazole wax and their deoxidizing waxes, ester waxes such as fatty acid ester wax, fatty acid amides, fatty acids, higher alcohols, fatty acid metal salts and mixtures thereof.

[0097] The flow softening point (T1 / 2) of the release agent was measured under the following conditions. <Method for measuring the flow softening point (T1 / 2)> Using a constant-force extrusion type capillary rheometer flow tester [for example, Shimadzu Corporation, CFT-500D], a 1g sample is heated at a heating rate of 6°C / min while a load of 1.96 MPa is applied by a plunger, and the sample is extruded from a nozzle with a diameter of 1 mm and a length of 1 mm. A graph of "plunger drop (flow value)" and "temperature" is drawn, and the temperature corresponding to half of the maximum value of the plunger drop is read from the graph. This value (the temperature when half of the sample has flowed out) is defined as the flow softening point (T1 / 2).

[0098] Examples of polyolefin waxes include (co)polymers of olefins (e.g., ethylene, propylene, 1-butene, isobutylene, 1-hexene, 1-dodecene, 1-octadecene, and mixtures thereof) [including those obtained by (co)polymerization and thermodeformable polyolefins], oxides of olefin (co)polymers by oxygen and / or ozone, maleic acid modified products of olefin (co)polymers [e.g., maleic acid and its derivatives (maleic anhydride, monomethyl maleate, monobutyl maleate, and dimethyl maleate, etc.) modified products], copolymers of olefins with unsaturated carboxylic acids [(meth)acrylic acid, itaconic acid, and maleic anhydride, etc.] and / or unsaturated carboxylic acid alkyl esters [(meth)acrylate (alkyl with 1 to 18 carbon atoms) esters and alkyl maleate (alkyl with 1 to 18 carbon atoms) esters, etc.], and sazole waxes.

[0099] Examples of higher alcohols include aliphatic alcohols with 30 to 50 carbon atoms, such as triacontanol. Examples of fatty acids include fatty acids with 30 to 50 carbon atoms, such as triacontanecarboxylic acid.

[0100] The charge control agent may contain either a positively charged charge control agent or a negatively charged charge control agent, and examples include nigrosine dyes, triphenylmethane dyes containing a tertiary amine as a side chain, quaternary ammonium salts, polyamine resins, imidazole derivatives, quaternary ammonium base-containing polymers, metal-containing azo dyes, copper phthalocyanine dyes, metal salicylate salts, boron complexes of benzyl acid, sulfonic acid group-containing polymers, fluorine-containing polymers, and halogen-substituted aromatic ring-containing polymers.

[0101] Examples of fluidizing agents include colloidal silica, alumina powder, titanium dioxide powder, and calcium carbonate powder.

[0102] The content of the binder for image-forming materials in the toner is preferably 68.4 to 97.4% by weight, based on the weight of the toner. The colorant content is preferably 1 to 30% by weight, more preferably 3 to 10% by weight, based on the toner weight. The release agent content is based on the toner weight and is preferably 1 to 10% by weight. The charge control agent content is preferably 0.5 to 7.5% by weight, based on the toner weight. The fluidizing agent content is based on the toner weight and is preferably 0.1 to 4% by weight. Furthermore, the total amount of additives is preferably 2.6 to 31.6% by weight, based on the toner weight. By setting the toner composition ratio within the above range, it is possible to easily obtain a toner with good hot offset resistance, heat storage resistance, and image stability.

[0103] The toner may be obtained by any of the known methods, such as the kneading and grinding method, the emulsification and phase inversion method, and the polymerization method. For example, when obtaining toner by a kneading and grinding method, the components constituting the toner, excluding the fluidizer, are dry-blended, then melt-kneaded, coarsely ground, and finally micronized using a jet mill or the like, and further classified to obtain fine particles with a volume-average particle size (D50) of preferably 5 to 20 μm, after which the fluidizer is mixed in to produce the toner. The volume-average particle size (D50) is measured using a Coulter counter [for example, product name: Multisizer III [manufactured by Beckman Coulter, Inc.]].

[0104] Furthermore, when obtaining toner by the emulsification phase inversion method, the components constituting the toner, excluding the fluidizing agent, are dissolved or dispersed in an organic solvent, then emulsified by adding water, and subsequently separated and classified for production. The volume-average particle size of the toner is preferably 3 to 15 μm.

[0105] Toner is mixed with carrier particles such as iron powder, glass beads, nickel powder, ferrite, magnetite, and resin (acrylic resin, silicone resin, etc.) as needed, and used as a developer for electrical latent images. When carrier particles are used, the weight ratio of toner to carrier particles is preferably 1 / 99 to 99 / 1. Alternatively, electrical latent images can be formed by friction with a component such as a charged blade instead of using carrier particles. Furthermore, the toner does not need to contain carrier particles.

[0106] Toner is fixed to a support material (paper, polyester film, etc.) by a copier, printer, etc., to become a recording material. Known methods such as thermal roll fixing and flash fixing can be applied to fix the toner to the support material.

[0107] The toner using the image-forming agent of the present invention is used for developing electrostatic images or magnetic latent images in electrophotography, electrostatic recording, electrostatic printing, and the like. More specifically, it is used for developing electrostatic images or magnetic latent images that are particularly suitable for full color.

[0108] This specification discloses the following:

[0109] (1) The present disclosure relates to a binder for image forming materials containing a polyester resin (A) obtained by polycondensation of an alcohol component and a carboxylic acid component, and bisphenol A, wherein the binder contains 20 to 60 mol% of ethylene glycol based on the total number of moles of the alcohol component, and 70 to 90 mol% of terephthalic acid based on the total number of moles of the carboxylic acid component, and the solubility parameter (SP value) of the polyester resin (A) is 10.5 to 11.7 (cal / cm³). 3 ) 1 / 2 This is a binder for image forming materials in which the bisphenol A content is 1 to 100 ppm based on the weight of the binder for image forming materials.

[0110] Disclosure (2) is an image-forming material binder according to Disclosure (1), wherein the image-forming material binder further contains phosphorus, and the phosphorus content is 10 to 400 ppm based on the weight of the image-forming material binder as measured by X-ray fluorescence.

[0111] Disclosure (3) is a binder for image-forming materials according to Disclosure (1) or (2) wherein the alcohol component of the polyester resin (A) contains an alkylene oxide adduct of bisphenol A.

[0112] Disclosure (4) is a binder for image forming materials according to any one of Disclosures (1) to (3), wherein the flow softening point (°C) of the polyester resin (A) is 120°C or less. [Examples]

[0113] The present invention will be further described below with reference to examples and comparative examples, but the present invention is not limited thereto.

[0114] <Manufacturing Example 1> [Manufacturing of Polyester Resin (A1)] In a pressurized reaction vessel, 62 parts by weight (39.6 mol%) of ethylene glycol and 381 parts by weight of recovered PET resin (equivalent to 71.5 mol% of ethylene glycol and 82.6 mol% of terephthalic acid) were added, and a depolymerization reaction (closed transesterification reaction) was carried out at 220°C for 2 hours with stirring to obtain the depolymer product. Next, the depolymer was cooled to 180°C, and 567 parts by weight (55.7 mol%) of bisphenol A·PO3 molar adduct, 90 parts by weight (15.2 mol%) of dodecenyl succinic anhydride, and 2 parts by weight of titanium diisopropoxybis(triethanol aminate) as a condensation catalyst were added. The temperature was raised to 220°C while the pressure was reduced to 0.5-2.5 kPa to remove 105 parts by weight (66.8 mol%) of ethylene glycol, and when the peak top molecular weight reached 7000, it was cooled to 175°C. Next, 9 parts by weight (2.2 mol%) of trimellitic anhydride was added, and esterification was carried out at atmospheric pressure at 175°C for 1 hour. After removal, polyester resin (A1) was obtained. Note that mol% refers to the content of each alcohol component or each carboxylic acid component based on the total number of moles of the alcohol component or carboxylic acid component, and the same applies to the following production examples.

[0115] <Manufacturing Example 2> [Manufacturing of Polyester Resin (A2)] In a pressurized reaction vessel, 285 parts by weight of recovered PET resin (equivalent to 65.7 mol% ethylene glycol and 71.1 mol% terephthalic acid), 631 parts by weight (76.0 mol%) of bisphenol A·PO3 molar adduct, 134 parts by weight (26.3 mol%) of dodecenyl succinic anhydride, and 2 parts by weight of titanium diisopropoxybis(triethanol aminate) as a condensation catalyst were added. The mixture was heated to 220°C while the pressure was reduced to 0.5-2.5 kPa to remove 53 parts by weight (41.7 mol%) of ethylene glycol, and the mixture was cooled to 175°C when the peak top molecular weight reached 8800. Next, 9 parts by weight (2.6 mol%) of trimellitic anhydride was added, and the mixture was esterified at atmospheric pressure at 175°C for 1 hour. After removal, polyester resin (A2) was obtained.

[0116] <Manufacturing Example 3> [Manufacturing of Polyester Resin (A3)] In a pressurized reaction vessel, 115 parts by weight (57.0 mol%) of ethylene glycol and 504 parts by weight of recovered PET resin (equivalent to 73.7 mol% of ethylene glycol and 89.4 mol% of terephthalic acid) were added, and a depolymerization reaction (closed transesterification reaction) was carried out at 220°C for 2 hours with stirring to obtain the depolymer product. Next, the depolymer was cooled to 180°C, and 127 parts by weight (9.9 mol%) of bisphenol A·PO3 molar adduct, 324 parts by weight (30.4 mol%) of bisphenol A·EO2 molar adduct, 63 parts by weight (8.8 mol%) of dodecenyl succinic anhydride, and 2 parts by weight of titanium diisopropoxybis(triethanol aminate) as a condensation catalyst were added. The temperature was raised to 220°C while the pressure was reduced to 0.5-2.5 kPa to remove 143 parts by weight (71.0 mol%) of ethylene glycol, and when the peak top molecular weight reached 7800, it was cooled to 175°C. Next, 9 parts by weight (1.8 mol%) of trimellitic anhydride was added, and the mixture was esterified at atmospheric pressure at 175°C for 1 hour. After removal, polyester resin (A3) was obtained.

[0117] <Manufacturing Example 4> [Manufacturing of Polyester Resin (A4)] In a pressurized reaction vessel, 67 parts by weight (38.3 mol%) of ethylene glycol and 490 parts by weight of recovered PET resin (equivalent to 82.4 mol% of ethylene glycol and 87.9 mol% of terephthalic acid) were added, and a depolymerization reaction (closed transesterification reaction) was carried out at 220°C for 2 hours with stirring to obtain the depolymer product. Next, the depolymer was cooled to 180°C, and 305 parts by weight (31.0 mol%) of bisphenol A·PO2 molar adduct, 209 parts by weight (18.4 mol%) of bisphenol A·PO3 molar adduct, 29 parts by weight (7.4 mol%) of phthalic anhydride, and 2 parts by weight of titanium diisopropoxybis(triethanol aminate) as a condensation catalyst were added. The temperature was raised to 220°C while the pressure was reduced to 0.5-2.5 kPa to remove 123 parts by weight (70.1 mol%) of ethylene glycol, and when the peak top molecular weight reached 9300, it was cooled to 175°C. Next, 24 parts by weight (4.7 mol%) of trimellitic anhydride was added, and the mixture was esterified at atmospheric pressure at 175°C for 1 hour. After removal, polyester resin (A4) was obtained.

[0118] <Manufacturing Example 5> [Manufacturing of Polyester Resin (A5)] In a pressurized reaction vessel, 67 parts by weight (38.4 mol%) of ethylene glycol and 394 parts by weight of recovered PET resin (equivalent to 66.9 mol% ethylene glycol and 72.4 mol% terephthalic acid) were added, and a depolymerization reaction (closed transesterification reaction) was carried out at 220°C for 2 hours while stirring to obtain the depolymerized product after the reaction. Next, the depolymer was cooled to 180°C, and 59 parts by weight (6.1 mol%) of bisphenol A·PO2 molar adduct, 421 parts by weight (37.4 mol%) of bisphenol A·PO3 molar adduct, 96 parts by weight (13.8 mol%) of dodecenyl succinic anhydride, 40 parts by weight (10.4 mol%) of phthalic anhydride, and 2 parts by weight of titanium diisopropoxybis(triethanol aminate) as a condensation catalyst were added. The mixture was then heated to 220°C while the pressure was reduced to 0.5-2.5 kPa to remove 96 parts by weight (48.8 mol%) of ethylene glycol, and when the peak top molecular weight reached 8700, it was cooled to 175°C. Next, 17 parts by weight (3.4 mol%) of trimellitic anhydride was added, and the mixture was esterified at atmospheric pressure at 175°C for 1 hour, after which it was removed to obtain polyester resin (A5).

[0119] <Manufacturing Example 6> [Manufacturing of Polyester Resin (A6)] In a pressurized reaction vessel, 62 parts by weight (33.1 mol%) of ethylene glycol and 452 parts by weight of recovered PET resin (equivalent to 71.2 mol% of ethylene glycol and 79.7 mol% of terephthalic acid) were added, and a depolymerization reaction (closed transesterification reaction) was carried out at 220°C for 2 hours with stirring to obtain the depolymer product. Next, the depolymer was cooled to 180°C, and 240 parts by weight (22.8 mol%) of bisphenol A·PO 2 molar adduct, 196 parts by weight (19.9 mol%) of bisphenol A·EO 2 molar adduct, 134 parts by weight (18.5 mol%) of dodecenyl succinic anhydride, and 2 parts by weight of titanium diisopropoxybis(triethanol aminate) as a condensation catalyst were added. The temperature was raised to 220°C while the pressure was reduced to 0.5-2.5 kPa to remove 88 parts by weight (46.9 mol%) of ethylene glycol, and when the peak top molecular weight reached 8000, it was cooled to 175°C. Next, 9 parts by weight (1.8 mol%) of trimellitic anhydride was added, and the mixture was esterified at atmospheric pressure at 175°C for 1 hour. After removal, polyester resin (A6) was obtained.

[0120] <Manufacturing Example 7> [Manufacturing of Polyester Resin (A7)] In a pressurized reaction vessel, 53 parts by weight (33.8 mol%) of ethylene glycol and 382 parts by weight of recovered PET resin (equivalent to 72.7 mol% of ethylene glycol and 82.5 mol% of terephthalic acid) were added, and a depolymerization reaction (closed transesterification reaction) was carried out at 220°C for 2 hours with stirring to obtain the depolymer product. Next, the depolymer was cooled to 180°C, and 44 parts by weight (5.1 mol%) of bisphenol A·PO2 molar adduct, 523 parts by weight (52.0 mol%) of bisphenol A·PO3 molar adduct, 91 parts by weight (15.3 mol%) of dodecenyl succinic anhydride, and 2 parts by weight of titanium diisopropoxybis(triethanol aminate) as a condensation catalyst were added. The temperature was raised to 220°C while the pressure was reduced to 0.5-2.5 kPa to remove 99 parts by weight (63.6 mol%) of ethylene glycol, and when the peak top molecular weight reached 7900, it was cooled to 175°C. Next, 9 parts by weight (2.2 mol%) of trimellitic anhydride was added, and the mixture was esterified at atmospheric pressure at 175°C for 1 hour. After removal, polyester resin (A7) was obtained.

[0121] <Manufacturing Example 8> [Manufacturing of Polyester Resin (A8)] In a pressurized reaction vessel, 76 parts by weight (29.2 mol%) of ethylene glycol and 731 parts by weight of recovered PET resin (equivalent to 82.8 mol% of ethylene glycol and 85.8 mol% of terephthalic acid) were added, and a depolymerization reaction (closed transesterification reaction) was carried out at 220°C for 2 hours with stirring to obtain the depolymer product. Next, the depolymer was cooled to 180°C, and 206 parts by weight (47.0 mol%) of neopentyl glycol, 130 parts by weight (12.0 mol%) of dodecenyl succinic anhydride, and 2 parts by weight of titanium diisopropoxybis(triethanolamine) as a condensation catalyst were added. The temperature was raised to 220°C while the pressure was reduced to 0.5-2.5 kPa to remove 154 parts by weight (59.1 mol%) of ethylene glycol, and when the peak top molecular weight reached 9400, it was cooled to 175°C. Next, 17 parts by weight (2.2 mol%) of trimellitic anhydride was added, and the mixture was esterified at atmospheric pressure at 175°C for 1 hour. After removal, polyester resin (A8) was obtained.

[0122] <Manufacturing Example 9> [Manufacturing of Amorphous Polyester Resin (A9)] In a pressurized reaction vessel, 148 parts by weight (97.5 mol%) of ethylene glycol, 304 parts by weight (82.5 mol%) of terephthalic acid, 89 parts by weight (10.4 mol%) of bisphenol A·PO2 molar adduct, 521 parts by weight (53.1 mol%) of bisphenol A·PO3 molar adduct, 91 parts by weight (15.3 mol%) of dodecenyl succinic anhydride, and 2 parts by weight of titanium diisopropoxybis(triethanol aminate) as a condensation catalyst were added. The mixture was heated to 220°C while the pressure was reduced to 0.5-2.5 kPa to remove 92 parts by weight (61.0 mol%) of ethylene glycol, and when the peak top molecular weight reached 8700, it was cooled to 175°C. Next, 9 parts by weight (2.2 mol%) of trimellitic anhydride was added, and esterification was carried out at atmospheric pressure at 175°C for 1 hour. After removal, amorphous polyester resin (A9) was obtained.

[0123] <Comparative Manufacturing Example 1> [Manufacturing of Polyester Resin (A'1)] In a pressurized reaction vessel, 64 parts by weight (39.7 mol%) of ethylene glycol and 432 parts by weight of recovered PET resin (equivalent to 79.8 mol% of ethylene glycol and 91.7 mol% of terephthalic acid) were added, and a depolymerization reaction (closed transesterification reaction) was carried out at 220°C for 2 hours with stirring to obtain the depolymer product. Next, the depolymer was cooled to 180°C, and 579.2 parts by weight (55.9 mol%) of bisphenol A·PO3 molar adduct, 37 parts by weight (6.1 mol%) of dodecenyl succinic anhydride, and 2 parts by weight of titanium diisopropoxybis(triethanol aminate) as a condensation catalyst were added. The temperature was raised to 220°C while the pressure was reduced to 0.5-2.5 kPa to remove 121 parts by weight (75.4 mol%) of ethylene glycol, and when the peak top molecular weight reached 6200, it was cooled to 175°C. Next, 9 parts by weight (2.2 mol%) of trimellitic anhydride was added, and the mixture was esterified at atmospheric pressure at 175°C for 1 hour. After removal, the mixture was removed to obtain polyester resin (A'1).

[0124] <Comparative Manufacturing Example 2> [Manufacturing of Polyester Resin (A'2)] In a pressurized reaction vessel, 270 parts by weight of recovered PET resin (equivalent to 61.2 mol% ethylene glycol and 68.0 mol% terephthalic acid), 625 parts by weight (74.1 mol%) of bisphenol A·PO3 molar adduct, 149 parts by weight (29.4 mol%) of dodecenyl succinic anhydride, and 2 parts by weight of titanium diisopropoxybis(triethanol aminate) as a condensation catalyst were added. The mixture was heated to 220°C while the pressure was reduced to 0.5-2.5 kPa to remove 46 parts by weight (35.2 mol%) of ethylene glycol, and the mixture was cooled to 175°C when the peak top molecular weight reached 8000. Next, 9 parts by weight (2.6 mol%) of trimellitic anhydride was added, and the mixture was esterified at atmospheric pressure at 175°C for 1 hour. After removal, polyester resin (A'2) was obtained.

[0125] <Comparative Manufacturing Example 3> [Manufacturing of Polyester Resin (A'3)] In a pressurized reaction vessel, 18 parts by weight (15.1 mol%) of ethylene glycol and 286 parts by weight of recovered PET resin (equivalent to 69.6 mol% of ethylene glycol and 70.1 mol% of terephthalic acid) were added, and a depolymerization reaction (closed transesterification reaction) was carried out at 220°C for 2 hours with stirring to obtain the depolymer product. Next, the depolymer was cooled to 180°C, and 629 parts by weight (79.9 mol%) of bisphenol A·PO3 molar adduct, 146 parts by weight (28.1 mol%) of dodecenyl succinic anhydride, and 2 parts by weight of titanium diisopropoxybis(triethanol aminate) as a condensation catalyst were added. The temperature was raised to 220°C while the pressure was reduced to 0.5-2.5 kPa to remove 78 parts by weight (64.6 mol%) of ethylene glycol, and when the peak top molecular weight reached 9500, it was cooled to 175°C. Next, 7 parts by weight (1.8 mol%) of trimellitic anhydride was added, and the mixture was esterified at atmospheric pressure at 175°C for 1 hour. After removal, polyester resin (A'3) was obtained.

[0126] <Comparative Manufacturing Example 4> [Manufacturing of Polyester Resin (A'4)] In a pressurized reaction vessel, 343 parts by weight of recovered PET resin (equivalent to 78.0 mol% ethylene glycol and 88.6 mol% terephthalic acid), 682 parts by weight (81.0 mol%) of bisphenol A·PO3 molar adduct, 43 parts by weight (8.8 mol%) of dodecenyl succinic anhydride, and 2 parts by weight of titanium diisopropoxybis(triethanol aminate) as a condensation catalyst were added. The mixture was heated to 220°C while the pressure was reduced to 0.5-2.5 kPa to remove 77 parts by weight (59.0 mol%) of ethylene glycol, and the mixture was cooled to 175°C when the peak top molecular weight reached 6900. Next, 9 parts by weight (2.6 mol%) of trimellitic anhydride was added, and the mixture was esterified at atmospheric pressure at 175°C for 1 hour. After removal, polyester resin (A'4) was obtained.

[0127] <Comparative Manufacturing Example 5> [Manufacturing of Polyester Resin (A'5)] In a pressurized reaction vessel, 27 parts by weight (13.4 mol%) of ethylene glycol and 493 parts by weight of recovered PET resin (equivalent to 71.9 mol% ethylene glycol and 89.6 mol% terephthalic acid) were added, and a depolymerization reaction (closed transesterification reaction) was carried out at 220°C for 2 hours while stirring to obtain the depolymerized product after the reaction. Next, the depolymer was cooled to 180°C, and 305 parts by weight (26.9 mol%) of bisphenol A·PO2 molar adduct, 179 parts by weight (13.6 mol%) of bisphenol A·PO3 molar adduct, 8 parts by weight (1.2 mol%) of dodecenyl succinic anhydride, 23 parts by weight (5.9 mol%) of phthalic anhydride, and 2 parts by weight of titanium diisopropoxybis(triethanol aminate) as a condensation catalyst were added. The mixture was then heated to 220°C while the pressure was reduced to 0.5-2.5 kPa to remove 52 parts by weight (25.9 mol%) of ethylene glycol, and when the peak top molecular weight reached 6100, it was cooled to 175°C. Next, 17 parts by weight (3.3 mol%) of trimellitic anhydride was added, and the mixture was esterified at atmospheric pressure at 175°C for 1 hour, after which it was removed to obtain polyester resin (A'5).

[0128] <Comparative Manufacturing Example 6> [Manufacturing of Polyester Resin (A'6)] In a pressurized reaction vessel, 114 parts by weight (63.2 mol%) of ethylene glycol and 459 parts by weight of recovered PET resin (equivalent to 75.0 mol% of ethylene glycol and 82.1 mol% of terephthalic acid) were added, and a depolymerization reaction (closed transesterification reaction) was carried out at 220°C for 2 hours with stirring to obtain the depolymer product. Next, the depolymer was cooled to 180°C, and 446 parts by weight (38.0 mol%) of bisphenol A·PO3 molar adduct, 114 parts by weight (16.0 mol%) of dodecenyl succinic anhydride, and 2 parts by weight of titanium diisopropoxybis(triethanol amination) as a condensation catalyst were added. The temperature was raised to 220°C while the pressure was reduced to 0.5-2.5 kPa to remove 138 parts by weight (76.2 mol%) of ethylene glycol, and when the peak top molecular weight reached 6900, it was cooled to 175°C. Next, 9 parts by weight (1.9 mol%) of trimellitic anhydride was added, and the mixture was esterified at atmospheric pressure at 175°C for 1 hour. After removal, polyester resin (A'6) was obtained.

[0129] Table 1 shows the composition and physical properties of polyester resin (A) and comparative polyester resin (A').

[0130] [Table 1]

[0131] <Manufacturing Example 10> [Manufacturing of Polyester Resin (B1)] In a pressurized reaction vessel equipped with a stirrer, heating / cooling device, thermometer, air inlet pipe, vacuum device, and water reduction device, 198 parts by weight of bisphenol A·PO2 molar adduct, 536 parts by weight of bisphenol A·PO3 molar adduct, 173 parts by weight of terephthalic acid, 67 parts by weight of adipic acid, and 6 parts by weight of trimellitic anhydride were added and stirred to homogenize. Then, 2 parts by weight of titanium diisopropoxybistriethanol laminate was added at 120°C and homogenized for 30 minutes. Esterilization under reduced pressure was carried out while increasing the temperature toward 227°C, and esterification under reduced pressure was carried out at 227°C for 5 hours while maintaining a pressure of 4 kPa or less, and it was confirmed that the acid value was 1 mg KOH / g or less. Then, it was cooled to 180°C, 79 parts by weight of trimellitic anhydride was charged, and the esterification reaction was carried out at atmospheric pressure for 1 hour, after which the temperature was increased under reduced pressure toward 205°C, and esterification under reduced pressure was carried out at 205°C. When the flow softening point reached 140°C, it was removed to obtain polyester resin (B1).

[0132] Table 2 shows the composition and physical properties of polyester resin (B1).

[0133] [Table 2]

[0134] <Example 1> [Manufacturing of binder (TB1) and toner (T1) for image forming materials] Using a Henschel mixer [FM10B, manufactured by Mitsui Miike Chemical Machinery Co., Ltd.], polyester resin (A1), polyester resin (B1), bisphenol A, and sodium phosphate were pre-mixed according to the mixing ratio (parts by weight) shown in Table 3 to obtain an image forming material binder (TB1). Next, the image forming material binder (TB1) was pre-mixed with a colorant, release agent, and charge control agent, and then kneaded in a twin-screw kneader [PCM-30, manufactured by Ikegai Co., Ltd.]. Then, after fine grinding using a supersonic jet pulverizer LabJet [manufactured by Nippon Pneumatic Mfg. Co., Ltd.], the material was classified using an airflow classifier [MDS-I, manufactured by Nippon Pneumatic Mfg. Co., Ltd.] to obtain toner particles with a particle size D50 of 7 μm. Then, 0.5 parts by weight of colloidal silica [Aerosil R972, manufactured by Nippon Aerosil Co., Ltd.] was mixed with 100 parts by weight of the toner particles in a sample mill to obtain toner (T1).

[0135] The colorants, release agents, and charge control agents listed in Table 3 are as follows: Coloring agent: Carbon Black MA-100 [Manufactured by Mitsubishi Chemical Corporation] Release agent: Carnauba wax [manufactured by Toyo Adore Co., Ltd.] Charge control agent: T-77 [Manufactured by Hodogaya Chemical Co., Ltd.]

[0136] <Examples 2-14> [Manufacturing of binders (TB2)-(TB14) and toners (T2)-(T14) for image forming materials] Image forming material binders (TB2) to (TB14) and toners (T2) to (T14) were obtained in the same manner as in Example 1, except that the mixing ratios (parts by weight) were as shown in Table 3.

[0137] <Comparative Examples 1-8> [Manufacturing of binders (TB'1)-(TB'8) and toners (T'1)-(T'8) for image forming materials] Image forming material binders (TB'1) to (TB'8) and toners (T'1) to (T'8) were obtained in the same manner as in Example 1, except that the mixing ratios (parts by weight) were as shown in Table 3.

[0138] [Evaluation Method] The following describes the measurement and evaluation methods for the low-temperature fixability, hot offset resistance, heat storage resistance, and pigment dispersibility of the obtained toners (T1) to (T14) and (T'1) to (T'8), including the criteria for evaluation.

[0139] <Low temperature retention> Toner is applied to the paper surface at a rate of 1.00 mg / cm². 2 The powder was spread evenly to achieve this. The method used to apply the powder to the paper involved using a printer with the heat fuser removed. This paper was passed through a soft roller at a fixing speed (heating roller peripheral speed) of 213 mm / second, with the heating roller temperature ranging from 100 to 200°C in 5°C increments. Next, the presence or absence of cold offset in the fixed image was visually inspected, and the temperature at which cold offset occurs (MFT) was measured. A lower cold offset generation temperature indicates superior low-temperature fixing performance. Under these evaluation conditions, the MFT temperature is generally preferably 125°C or lower.

[0140] <Hot offset resistance> Using the same method as described above for low-temperature fixing, toner was placed on the paper, and this paper was passed through a soft roller at a fixing speed (peripheral speed of the heating roller) of 213 mm / second, with the heating roller temperature ranging from 100 to 200°C in 5°C increments. Next, we visually inspected the fixed image for the presence or absence of hot offset and measured the temperature at which hot offset occurred. A higher temperature at which hot offset occurs indicates superior resistance to hot offset. Under these evaluation conditions, a temperature of 180°C or higher is preferable.

[0141] <Heat-resistant storage stability> 1 g of toner and 0.013 g of Aerosil R8200 (manufactured by Evonik Japan Co., Ltd.) were mixed in a shaker for 1 hour. The mixture was placed in a sealed container and left to stand for 24 hours in an atmosphere of 50°C and 80% relative humidity. The coagulation properties were measured using a powder tester to evaluate the heat resistance and storage properties. A lower cohesion test value, determined by the method described below, indicates superior heat resistance and storage properties. Under these evaluation conditions, a cohesion level of 5% or less is preferable. Equipment: POWDER TESTER model PT-X (manufactured by Hosokawa Micron) Sieve mesh sizes: 355μm, 250μm, 150μm Vibration width: 1mm Vibration time: 30 seconds Operating procedure: Place the sieves on the powder tester's vibrating platform in the following order: top 355μm, middle 250μm, and bottom 150μm. Place 1g of toner on the top sieve and vibrate for 30 seconds with a vibration amplitude of 1mm. Measure the weight of the toner remaining on each sieve. Cohesiveness: Calculated from the weight of toner used for measurement and the weight of remaining toner after sieving. Cohesion degree (%)=(U / N+M / N×3 / 5+L / N×1 / 5)×100 U: Weight of the top layer, M: Weight of the middle layer, L: Weight of the bottom layer, N: Weight of the sample (1g)

[0142] <Pigment dispersibility> Toner was thinly sectioned and stained with ruthenium tetroxide at a concentration of 1 for 3 minutes using a vacuum electron staining device (VSC1R1H, manufactured by Philgen Co., Ltd.). The cross-section of the toner was then observed at a magnification of 10,000x using a transmission electron microscope (TEM) [Hitachi H-7100, manufactured by Hitachi, Ltd.]. The particle size (average of major and minor diameters) of 100 observed pigment particles was measured, and this average particle size was used as an indicator of pigment dispersibility. A dispersion diameter of less than 1.0 μm indicates excellent pigment dispersibility. [Judgment criteria] A: Less than 0.5 μm B: 0.5 μm or larger, less than 0.7 μm C: 0.7 μm or larger, less than 1.0 μm D:1.0μm or more

[0143] [Table 3]

[0144] As is clear from the evaluation results in Table 3, all toners (T1) to (T14) used in the examples yielded excellent results in all performance evaluations. On the other hand, the toners (T'1) to (T'8) in the comparative example were defective in several performance items. [Industrial applicability]

[0145] The binder for image forming materials of the present invention maintains low-temperature fixability and hot offset resistance while exhibiting excellent heat resistance and pigment dispersibility, making it suitable for use as a toner for electrostatic image development in electrophotography, electrostatic recording, electrostatic printing, and the like. Furthermore, it is suitable for applications such as inkjet binders, paint additives, adhesive additives, and particles for electronic paper.

Claims

1. A binder for image forming materials containing a polyester resin (A) obtained by polycondensation of an alcohol component and a carboxylic acid component, and bisphenol A, wherein the binder contains 20 to 60 mol% of ethylene glycol based on the total number of moles of the alcohol component, and 70 to 90 mol% of terephthalic acid based on the total number of moles of the carboxylic acid component, and the solubility parameter (SP value) of the polyester resin (A) is 10.5 to 11.7 (cal / cm³). ３ ) １／２ A binder for image forming materials, wherein the bisphenol A content is 1 to 100 ppm based on the weight of the binder for image forming materials.

2. The binder for image forming materials according to claim 1, wherein the binder for image forming materials further contains phosphorus, and the phosphorus content is 10 to 400 ppm based on the weight of the binder for image forming materials as measured by fluorescent X-ray.

3. The binder for image-forming materials according to claim 1 or 2, wherein the alcohol component of the polyester resin (A) contains an alkylene oxide adduct of bisphenol A.

4. The binder for image forming materials according to claim 1 or 2, wherein the flow softening point (°C) of the polyester resin (A) is 120°C or lower.

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