Binder for image forming material

Abstract

To provide a binder for image forming material that satisfies all of heat-resistant storage properties, image quality stability, and hydrolysis resistance, while maintaining low temperature fixability and hot offset resistance.SOLUTION: A binder for image forming material includes a polyester resin (A) obtained through polycondensation of an alcohol component and a carboxylic acid component, contains 20-60 mol% of ethylene glycol on the basis of the total number of moles of the alcohol component, and contains 70-90 mol% of a terephthalic acid on the basis of the total number of moles of the carboxylic acid component. The polyester resin (A) has a solubility parameter (SP value) of 10.5-11.5 (cal / cm3)1 / 2, and the polyester resin (A) has an acid value of 15 mgKOH / g or less.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a binder for an imaging material. [Background technology]

[0002] 2. Description of the Related Art In recent years, with the development of electrophotographic systems, the demand for electrophotographic apparatuses such as copying machines and laser printers has increased rapidly, and the requirements for their performance have also become more sophisticated. For full-color electrophotography, a method and apparatus have been known in which a latent image based on color image information is formed on a latent image carrier such as an electrophotographic photosensitive member, the latent image is developed with a toner of a corresponding color, and then the toner image is transferred onto a transfer material. After repeating such image forming steps, the toner image on the transfer material is heated and fixed to obtain a multi-color image.

[0003] To pass through these processes without any problems, the toner must first maintain a stable charge, and then must have good fixability to paper. In addition, the toner must not block in the device because the fixing section of the device has a heater, causing the temperature to rise inside the device.

[0004] Furthermore, in order to promote miniaturization, speedup, and image quality improvement of electrophotographic apparatuses, as well as to save energy by reducing the energy consumption in the fixing step, there is a strong demand for improving the low-temperature fixing property of toner. Recently, many kinds of paper are used as transfer materials, such as recycled paper with large surface irregularities and coated paper with a smooth surface. To deal with the surface properties of these transfer materials, a fixing device with a wide nip width, such as a soft roller or a belt roller, is preferably used. However, when the nip width is widened, the contact area between the toner and the fixing roller increases, and the melted toner adheres to the fixing roller, which is called a high-temperature offset phenomenon, occurs, so offset resistance is required. In addition to the above, multi-color images (full color) require a much higher gloss than black-and-white images (monochrome) in order to reproduce photographic images, etc., and it is necessary to ensure that the toner layer of the resulting image is smooth. Therefore, it is necessary to develop low-temperature fixability while maintaining high gloss and offset resistance, and there is a demand for toner images with high gloss over a wide working range.

[0005] The binder for the image-forming material has a large effect on the toner characteristics as described above. Known binders include polystyrene resin, styrene-acrylic resin, polyester resin, epoxy resin, polyurethane resin, polyamide resin, etc., and recently, polyester resin has been attracting particular attention because it is easy to balance storage stability and fixability.

[0006] As a method for expanding the fixing temperature range, a toner using a polyester resin containing an unsaturated carboxylic acid as a constituent has been proposed (Patent Document 1). However, although this method can prevent the offset phenomenon at high temperatures to some extent, the minimum fixing temperature is insufficient, and the method does not yet fully meet the demands for higher speed and energy saving.

[0007] Meanwhile, many toners using hybrid resins in which a polyester component and a styrene-acrylic component are chemically bonded have been proposed (Patent Documents 2 to 6). Although this method improves hot offset resistance, charging characteristics and pulverizability, the low-temperature fixability is still insufficient.

[0008] As described above, there has not been a binder for an image-forming material that satisfies all of the requirements for heat-resistant storage stability, image quality stability, and hydrolysis resistance while maintaining low-temperature fixing property and hot offset resistance. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2017-003985 A [Patent Document 2] JP 2007-286562 A [Patent Document 3] JP 2014-235362 A [Patent Document 4] JP 2008-009171 A [Patent Document 5] JP 2010-128466 A [Patent Document 6] JP 2006-047585 A Summary of the Invention [Problem to be solved by the invention]

[0010] An object of the present invention is to provide a binder for an image-forming material which satisfies all of the requirements for heat-resistant storage stability, image quality stability, and hydrolysis resistance while maintaining low-temperature fixing property and hot offset resistance. [Means for solving the problem]

[0011] The present inventors conducted extensive research to solve these problems and arrived at the present invention. That is, the present invention relates to a binder for an image-forming material, which comprises a polyester resin (A) obtained by polycondensing an alcohol component and a carboxylic acid component, the binder comprising: a polyester resin (A) containing 20 to 60 mol % of ethylene glycol based on the total number of moles of the alcohol component; and a polyester resin (A) containing 70 to 90 mol % of terephthalic acid based on the total number of moles of the carboxylic acid component; and the polyester resin (A) has a solubility parameter (SP value) of 10.5 to 11.5 (cal / cm 3 ) 1 / 2 and the acid value of the polyester resin (A) is 15 mgKOH / g or less. Effect of the Invention

[0012] According to the present invention, it is possible to provide heat-resistant storage stability, image quality stability and hydrolysis resistance while maintaining low-temperature fixability and hot offset resistance. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The binder for an image-forming material of the present invention is a binder for an image-forming material comprising a polyester resin (A) obtained by polycondensation of an alcohol component and a carboxylic acid component, the binder containing 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 11.5 (cal / cm 3 ) 1 / 2 and the acid value of the polyester resin (A) is 15 mgKOH / g or less. The binder for the image-forming material of the present invention will be described below in order.

[0014] The binder for an image-forming material of the present invention contains a polyester resin (A) obtained by polycondensing an alcohol component and a carboxylic acid component, contains 20 to 60 mol % of ethylene glycol based on the total number of moles of the alcohol component, and contains 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 11.5 (cal / cm 3 ) 1 / 2 and the acid value of the polyester resin (A) is 15 mgKOH / g or less.

[0015] The polyester resin (A) may be either an amorphous polyester resin or a crystalline polyester resin, and is preferably an amorphous polyester resin from the viewpoint of grindability. The polyester resin (A) may be either an unsaturated polyester resin or a saturated polyester resin, and is preferably a saturated polyester resin from the viewpoint of low-temperature fixability and grindability. These may be used alone or in combination of two or more. In the present invention, "crystalline" means that in differential scanning calorimetry (also referred to as DSC measurement) described below, the DSC curve has a clear endothermic peak top temperature (Tm). Also, "amorphous" means that when the transition temperature of a sample is measured using a differential scanning calorimeter described below, there is no endothermic peak top temperature. The measurement is performed using a differential scanning calorimeter {e.g., "DSC210" [manufactured by Seiko Instruments Inc.]}. The crystalline resin is heated for the first time from 20°C to 150°C at 10°C / min, then cooled from 150°C to 0°C at 10°C / min, and then heated for the second time from 0°C to 150°C at 10°C / min. The temperature showing the top of the endothermic peak during the second heating process is taken as the peak top temperature of the endothermic peak of the crystalline resin. In the present invention, the unsaturated polyester resin refers to a polyester resin having a radically reactive carbon-carbon double bond. In determining whether a polyester resin is an unsaturated polyester resin or a saturated polyester resin, the double bonds of an aromatic ring or a heterocyclic ring are not taken into consideration.

[0016] The polyester resin (A) contains an alcohol component of ethylene glycol. The polyester resin (A) may contain an alcohol component (x) in addition to ethylene glycol. Examples of the alcohol component (x) include monools (x1), diols other than ethylene glycol (x2), and tri- or higher valent polyols (x3). These may be used alone or in combination of two or more.

[0017] Examples of the monool (x1) include linear or branched alkyl alcohols having 1 to 30 carbon atoms (such as methanol, ethanol, isopropanol, 1-decanol, dodecyl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, arachidyl alcohol, behenyl alcohol, and lignoceryl alcohol). Among these saturated monools, from the viewpoints of image strength and heat-resistant storage stability, preferred are linear or branched alkyl alcohols having 8 to 24 carbon atoms, more preferred are linear alkyl alcohols having 8 to 24 carbon atoms, and even more preferred are dodecyl alcohol, stearyl alcohol, arachidyl alcohol, behenyl alcohol and lignoceryl alcohol.

[0018] Examples of the diol (x2) include alkylene glycols having 3 to 36 carbon atoms (1,2-propylene glycol, 1,3-propylene glycol, 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, 1,12-dodecanediol, and the like) (x22), alkylene ether glycols having 4 to 36 carbon atoms (diethylene glycol, triethylene glycol, dipropylene glycol, polyethylene glycol, Examples of the AO adducts include ethylene oxide (hereinafter sometimes abbreviated as EO) adducts, propylene oxide (hereinafter sometimes abbreviated as PO) adducts, and propylene oxide (hereinafter sometimes abbreviated as PO) adducts. The AO adducts include ethylene oxide (hereinafter sometimes abbreviated as EO) adducts, propylene oxide (hereinafter sometimes abbreviated as PO) adducts, and the like. Examples of the AO adducts include ethylene oxide (hereinafter sometimes abbreviated as EO) adducts, propylene oxide (hereinafter sometimes abbreviated as PO) adducts, and the like. Examples of the AO adducts include ethylene oxide (hereinafter sometimes abbreviated as EO) adducts, propylene oxide (hereinafter sometimes abbreviated as PO) adducts, and the like. Of these diols (x2), from the viewpoints of low-temperature fixability and heat-resistant storage stability, preferred are alkylene glycols (x22) having 3 to 36 carbon atoms and alkylene oxide adducts of aromatic diols (x27), and more preferred are ethylene oxide adducts and propylene oxide adducts of bisphenols.

[0019] The 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; 2 represents -, -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] Examples of bisphenols include 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.

[0022] From the viewpoints of low-temperature fixability and heat-resistant storage stability, the average number of moles of the ethylene oxide adduct of the aromatic diol and the propylene oxide adduct of the aromatic diol 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] Examples of the polyol (x3) having a valence of three or more include aliphatic polyhydric alcohols having a valence of three or more and having 3 to 36 carbon atoms (x31), sugars and derivatives thereof (x32), AO adducts of aliphatic polyhydric alcohols (the average number of moles added is preferably 1 to 30) (x33), AO adducts of trisphenols (trisphenol PA, etc.) (the average number of moles added is preferably 2 to 30) (x34), and AO adducts of novolak resins (including phenol novolak and cresol novolak, etc., the average degree of polymerization is preferably 3 to 60) (the average number of moles added is preferably 2 to 30) (x35).

[0024] Examples of the aliphatic polyhydric alcohol (x31) having 3 to 36 carbon atoms and a valence of 3 or more include alkane polyols and their intramolecular or intermolecular dehydration products, such as glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, sorbitol, sorbitan, polyglycerin, and dipentaerythritol.

[0025] Examples of sugars and their derivatives (x32) include sucrose and methyl glucoside.

[0026] Of the tri- or higher valent polyols (x3), from the viewpoint of achieving both low-temperature fixing properties and hot offset resistance, preferred are tri- or higher valent aliphatic polyhydric alcohols (x31) having 3 to 36 carbon atoms and AO adducts (average number of moles added is preferably 2 to 30) (x35) of novolak resins (including phenol novolak and cresol novolak, etc., with an average degree of polymerization preferably being 3 to 60).

[0027] As the alcohol component (x), a diol (x2) and a polyol (x3) having a valence of three or more can be used in combination. When used in combination, the molar ratio of ethylene glycol and the diol (x2) to the polyol (x3) having a valence of three or more, [(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 viewpoints of low-temperature fixing property and hot offset resistance.

[0028] The polyester resin (A) contains terephthalic acid as a carboxylic acid component. The polyester resin (A) may contain a carboxylic acid component (y) in addition to terephthalic acid. Examples of the carboxylic acid component (y) include aromatic carboxylic acids (y1) other than terephthalic acid and aliphatic carboxylic acids (y2), etc. The carboxylic acid component (y) may be used alone or in combination of two or more.

[0029] Examples of the aromatic carboxylic acid (y1) include aromatic dicarboxylic acids having 8 to 36 carbon atoms (such as phthalic acid, isophthalic acid, and naphthalenedicarboxylic acid) and aromatic polycarboxylic acids having 9 to 20 carbon atoms and having three or more valences (such as trimellitic acid and pyromellitic acid). Examples of the aliphatic carboxylic acid (y2) include aliphatic dicarboxylic acids having 2 to 50 carbon atoms (oxalic acid, malonic acid, succinic acid, adipic acid, suberic acid, sebacic acid, etc.), alicyclic dicarboxylic acids having 6 to 40 carbon atoms [dimer acids (dimerized linoleic acid, etc.)], alkene dicarboxylic acids having 4 to 36 carbon atoms (alkenylsuccinic acids such as dodecenylsuccinic acid, maleic acid, fumaric acid, citraconic acid, mesaconic acid, etc.), and the like.

[0030] As the carboxylic acid component (y), anhydrides and lower alkyl (carbon number 1 to 4) esters (methyl ester, ethyl ester, isopropyl ester, etc.) of these carboxylic acids may be used, or may be used in combination with these carboxylic acids.

[0031] Of these carboxylic acid components (y), from the viewpoint of achieving both low-temperature fixing ability and hot offset resistance, preferred are aliphatic dicarboxylic acids having 4 to 10 carbon atoms, alkenylsuccinic acid, isophthalic acid, trimellitic acid, pyromellitic acid, and combinations thereof. Particularly preferred are adipic acid, dodecenylsuccinic acid, trimellitic acid, and combinations thereof. Similarly preferred are anhydrides and lower alkyl esters of these acids.

[0032] The polyester resin (A) may be a polyester resin such as polyethylene terephthalate (hereinafter also referred to as PET) resin or its depolymerized product. For example, recycled PET resin is used, which is PET resin collected from the market (hereinafter referred to as recycled PET resin). Examples of recycled PET resin include PET bottles and PET films.

[0033] The total charging ratio of the alcohol component and the carboxylic acid component of the polyester resin (A) is preferably 2 / 1 to 1 / 2, more preferably 1.5 / 1 to 1 / 1.3, and even more preferably 1.4 / 1 to 1 / 1.2, in terms of the equivalent ratio (molar ratio) of hydroxyl groups to carboxyl groups ([OH] / [COOH]).

[0034] Among the alcohol components of the polyester resin (A), the content of ethylene glycol is 20 to 60 mol %, preferably 30 to 50 mol %, and more preferably 35 to 45 mol %, based on the total moles of the alcohol components. If the ethylene glycol content is less than 20 mol %, the hot offset resistance deteriorates, whereas if it exceeds 60 mol %, the low temperature fixability and hydrolysis resistance deteriorate.

[0035] Among the alcohol components in the polyester resin (A), the content of alcohol components other than 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 moles of the alcohol components.

[0036] Among the carboxylic acid components of the polyester resin (A), the content of terephthalic acid 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 the carboxylic acid components. If the content of terephthalic acid is less than 70 mol %, the heat resistant storage stability deteriorates, whereas if it exceeds 90 mol %, the hydrolysis resistance deteriorates.

[0037] Among the carboxylic acid components in the polyester resin (A), the content of carboxylic 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 moles of the carboxylic acid components.

[0038] The polyester resin (A) preferably has a calcium element content of 10 to 4000 ppm based on the weight of the polyester resin (A) as measured by fluorescent X-rays. The content of calcium element contained in the polyester resin (A) can be determined by adjusting the amount of the calcium element-containing compound added during the production of the polyester resin (A). Examples of calcium element-containing compounds include calcium carbonate, calcium hydrogen carbonate, calcium chloride, calcium sulfate, calcium oxide, calcium phosphate, calcium hydroxide, calcium hydride, calcium acetate, calcium aliphatic carboxylates, and calcium aromatic carboxylates.

[0039] In this specification, the quantitative determination of the calcium element content by fluorescent X-rays will be described below. <Sample preparation> The pressure molding method can be used to compress powders such as binders and toners for image forming materials into pellets. For example, a powder sample can be filled into the center of a 5 mm thick ring made of polyvinyl chloride resin to form a light mound, and then pressed into pellets using a press machine with a load of 10 tonnes. Care must be taken to avoid contamination with other components, especially calcium element. In particular, in the case of toner, the external additives may contain calcium element, so the toner must first be ultrasonically cleaned with methanol or the like to remove the external additives from the surface, and then a sample must be analyzed using surface analysis such as STEM to confirm that the external additives have been removed. This makes it possible to accurately measure the calcium element content. <Measurement method> It is possible to prepare a calibration curve using a standard sample whose calcium element concentration is known in advance, and determine the analytical value from the X-ray intensity of the analytical sample, or, if the composition of most of the resin is known, to obtain an approximate content by the fundamental parameter method (FP method). However, except in cases where the contents of toner, etc. are unknown, the FP method is relatively inferior in accuracy, so it is preferable to use the calibration curve method, which can measure calcium element concentration more accurately. <Measurement equipment> For example, the measurement can be performed using an X-ray fluorescence analyzer (Rigaku Corporation, Supermini200) or the like.

[0040] By using a polyester resin synthesized in a state containing calcium element, the amount of cyclic compounds in the toner is reduced. When the amount of cyclic compounds in the toner is reduced, the heat-resistant storage stability of the toner can be improved.

[0041] The polyester resin (A) preferably contains phosphorus element in the range of 2 to 500 ppm based on the weight of the polyester resin (A) as measured by fluorescent X-rays. The content of phosphorus in the polyester resin (A) can be determined by adjusting the amount of the phosphorus-containing compound added during the production of the polyester resin (A). In this specification, the content of phosphorus element can be quantified by fluorescent X-rays in the same manner as the content of calcium element.

[0042] In the binder for image-forming materials of the present invention, the polyester resin (A) has a peak top molecular weight (Mp) in gel permeation chromatography (GPC) of preferably 3,000 to 10,000, and more preferably 4,000 to 8,000, from the viewpoints of low-temperature fixability, hot offset resistance, and heat-resistant storage stability.

[0043] 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): Tosoh Corporation HLC-8120 Column (example): 2 TSK GEL GMH6 [Tosoh Corporation] Measurement temperature: 40℃ Sample solution: 0.25% by weight in THF Solution injection volume: 100μL Detector: Refractive index detector Reference material: 12 standard polystyrenes (TSKstandard POLYSTYRENE) manufactured by Tosoh Corporation (molecular weight: 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) For measuring the molecular weight, a sample is dissolved in THF to a concentration of 0.25% by weight, and the insoluble matter is filtered off using a glass filter to obtain a sample solution.

[0044] In the binder for the image-forming material of the present invention, the glass transition temperature (Tg A ) is preferably 50 to 70°C. Tg A When the glass transition temperature (Tg) of the polyester resin (A) is 70° C. or lower, the low-temperature fixing property is good, and when the glass transition temperature (Tg) of the polyester resin (A) is 50° C. or higher, the heat-resistant storage property is good. A ) is measured, for example, using a DSC Q20 manufactured by TA Instruments, in accordance with the method (DSC method) specified in ASTM D3418-82.

[0045] The acid value of the polyester resin (A) is 15 mgKOH / g or less, and from the viewpoint of low-temperature fixability and hydrolysis resistance, it is preferably 3 to 15 mgKOH / g, more preferably 5 to 12 mgKOH / g. It is even more preferably 6 to 10 mgKOH / g. If it exceeds 15 mgKOH / g, the heat-resistant storage stability and image stability are deteriorated. The acid value of the polyester resin (A) can be measured by the method specified in JIS K0070 (1992).

[0046] From the viewpoints of low-temperature fixability and hydrolysis resistance, the hydroxyl value of the polyester resin (A) is preferably 60 mgKOH / g or less, more preferably 20 to 55 mgKOH / g, and even 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).

[0047] The solubility parameter (SP value) of polyester resin (A) is 10.5 to 11.5 (cal / cm 3 ) 1 / 2 , preferably 10.7 to 11.3, and more preferably 10.8 to 11.2. The SP value of (A) is 10.5 (cal / cm 3 ) 1 / 2 If it is less than 11.5 (cal / cm 3 ) 1 / 2 If it exceeds this value, the low-temperature fixability and hydrolysis resistance are deteriorated. The SP value in the present invention is a value calculated at 25° C. by the method described in Polymer Engineering and Science, Vol. 14, pp. 151-154, by Robert F. Fedors et al.

[0048] The flow softening point (°C) of the polyester resin (A) is preferably 120°C or lower, more preferably 90°C to 110°C, and even more preferably 95°C to 105°C, from the viewpoint of low-temperature fixability.

[0049] The flow softening point (° C.) of the polyester resin (A) was measured under the following conditions. <Flow softening point measurement method> Using a descending flow tester [e.g., CFT-500D, manufactured by Shimadzu Corporation], 1 g of the measurement sample is heated at a heating rate of 6°C / min while applying a load of 1.96 MPa with the plunger and extruding it from a nozzle of 1 mm diameter and 1 mm length. A graph is then drawn of "plunger descending amount (flow value)" versus "temperature," and the temperature corresponding to half the maximum value of the plunger descending amount is read from the graph. This value (the temperature when half of the measurement sample has flowed out) is taken as the flow softening point (°C).

[0050] In the binder for image-forming materials of the present invention, the polyester resin (A) can be produced 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 that the polycondensation reaction is carried out.

[0051] In this case, an esterification catalyst can be used as necessary. Examples of the esterification catalyst include tin-containing catalysts (e.g., dibutyltin oxide, etc.), antimony trioxide, titanium-containing catalysts [e.g., titanium alkoxide, potassium oxalate titanate, titanium terephthalate, titanium alkoxide terephthalate, catalysts described in JP-A-2006-243715 {titanium diisopropoxy bis(triethanol aminate), titanium dihydroxy bis(triethanol aminate), titanium monohydroxy tris(triethanol aminate), titanyl bis(triethanol aminate) and their intramolecular polycondensates, etc.} and catalysts described in JP-A-2007-11307 (titanium tributoxy terephthalate, titanium triisopropoxy terephthalate and titanium diisopropoxy diterephthalate, etc.)], zirconium-containing catalysts (e.g., zirconyl acetate, etc.) and zinc acetate, etc. Among these, titanium-containing catalysts are preferred. It is also effective to reduce the pressure in order to improve the reaction rate at the end of the reaction.

[0052] The binder for an image-forming material of the present invention may further contain a polyester resin (C) other than the polyester resin (A). Examples of the alcohol component and carboxylic acid component constituting the polyester resin other than the polyester resin (A) include the same components as the alcohol component and carboxylic acid component exemplified as the constituent components of the polyester resin (A).

[0053] The polyester resin (C) preferably has a peak top molecular weight (Mp) in gel permeation chromatography (GPC) of 1,000 to 100,000 from the viewpoints of low-temperature fixability, hot offset resistance, and heat-resistant storage stability. The Mp, Mn, and Mw of the polyester resin (C) can be measured under the same conditions as those of the polyester resin (A).

[0054] From the viewpoint of hot offset resistance, the flow softening point (° C.) of the polyester resin (C) 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 the polyester resin (C) can be measured in the same manner as the flow softening point of the polyester resin (A).

[0055] The acid value of the polyester resin (C) is preferably 40 mgKOH / g or less, more preferably 30 mgKOH / g or less, and further preferably 5 to 30 mgKOH / g, from the viewpoints of low-temperature fixability and hydrolysis resistance. The acid value of the polyester resin (C) can be measured by the method specified in JIS K0070 (1992).

[0056] In the binder for the image-forming material of the present invention, the glass transition temperature (Tg C ) is preferably 50 to 70°C. Tg C When the temperature is 70° C. or lower, the low-temperature fixability is good, and when the temperature is 50° C. or higher, the heat-resistant storage stability is good. The glass transition temperature (Tg) of the polyester resin (A) is measured by the method (DSC method) specified in ASTM D3418-82 using, for example, DSC Q20 manufactured by TA Instruments Co., Ltd.

[0057] When the binder for an image-forming material of the present invention contains a polyester resin (C), the weight ratio of the polyester resin (A) to the polyester resin (C) [(A) / (C)] is preferably 50 / 50 to 90 / 10 in terms of achieving both low-temperature fixability, hot offset resistance, and heat-resistant storage stability.

[0058] In the binder for the image-forming material of the present invention, from the viewpoint of compatibility, the absolute value of the difference between the SP value of the polyester resin (A) and the SP value of the polyester resin (C) is preferably 1.3 (cal / cm 3 ) 1 / 2 The following is the result.

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

[0060] The polyfunctional vinyl monomer (a) includes divalent vinyl monomers and trivalent or higher vinyl monomers. These may be used alone or in combination of two or more.

[0061] Examples of the divalent vinyl monomer 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 trivalent or higher vinyl monomers include trimethylolpropane tri(meth)acrylate, 1,3,5-benzenetricarboxylate triallyl, tri(meth)acrylate of glycerin, tri(meth)acrylate of pentaerythritol; and tri(meth)acrylate of an 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 an ethylene oxide adduct of dipentaerythritol, penta(meth)acrylate of an ethylene oxide adduct of dipentaerythritol, and penta(meth)acrylate of a propylene oxide adduct of dipentaerythritol.

[0063] Among these polyfunctional vinyl monomers (a), divinylbenzene and trimethylolpropane triacrylate are preferred from the viewpoints of low-temperature fixing property, hot offset resistance and pulverizability.

[0064] From the viewpoint of hot offset resistance, heat-resistant storage stability, pulverizability and charge stability of the toner, the vinyl resin (B) may contain a monomer (b) other than the polyfunctional vinyl monomer (a) as a constituent monomer. As the monomer (b), those having a styrene-based monomer (b1), a (meth)acrylic monomer (b2), a vinyl ester monomer (b3) and a monomer (b4) having a nitrile group as a constituent monomer are preferable. The monomer (b) may be used alone or in combination of two or more kinds.

[0065] Examples of the styrene-based monomer (b1) include styrene and alkylstyrenes having an alkyl group with 1 to 3 carbon atoms (eg, α-methylstyrene and p-methylstyrene).

[0066] Examples of the (meth)acrylic monomer (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 the vinyl ester monomer (b3) include vinyl acetate, vinyl propionate, and isopropenyl acetate.

[0068] An example of the 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 proportion of the polyfunctional vinyl monomer (a) in the monomers constituting the vinyl resin (B) is preferably 0.1 to 10% by weight based on the total weight of the monomers, from the viewpoints of hot offset resistance and crushability.

[0071] The monomers constituting the vinyl resin (B) preferably further contain a monomer (b), and from the viewpoints of hot offset resistance and crushability, the monomer (b) is preferably 90 to 99.9% by weight based on the total weight of the monomers.

[0072] In the binder for the image-forming material of the present invention, the glass transition temperature (Tg B ) is preferably −35 to 47° C. Tg B When the glass transition temperature (Tg B ) is the Fox-Flory equation, 1 / Tg 12 =φ(1) / Tg 1 +φ(2) / Tg 2 Tg is the value calculated by 12 corresponds to the Tg of vinyl resin (B) at absolute temperature (unit: K), and Tg 1 and Tg 2 is the glass transition temperature (unit: K) of the homopolymer of each of the monomers constituting the vinyl resin (B), and φ(1) and φ(2) are the weight percentages of the monomers constituting the vinyl resin (B).

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

[0074] The acid value of the vinyl resin (B) is preferably 55 mgKOH / g or less from the viewpoint of low-temperature fixability. The acid value of the vinyl resin (B) is calculated as a weight percentage using the acid value of each of the monomers used in the polymerization of the vinyl resin (B) and the weight of the monomer.

[0075] The vinyl resin (B) in the binder for image-forming material 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 JP-A-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). In addition, in the above-mentioned solution polymerization method, producing the vinyl resin (B) in the presence of the polyester resin (A) instead of a solvent is preferable from the viewpoint of achieving both grindability and hot offset resistance, since the vinyl resin (B) can be uniformly crosslinked in the polyester resin (A).

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

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

[0078] The organic peroxide (c2) is not particularly limited, and examples thereof 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-butylperoxyhexyne-3, acetyl peroxide, isobutyryl peroxide, octanyl peroxide, and decanolyl peroxide. , 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 and diazo compound (c3) are not particularly limited, but examples thereof include 2,2'-azobis-(2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1,1'-azobis(cyclohexane-1-carbonitrile), 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-butylperoxy-2-ethylhexanoate and di-t-butyl peroxide are more preferred.

[0081] When the binder for an image-forming material of the present invention contains a vinyl resin (B), it can be obtained by, for example, mixing a polyester resin (A) and a vinyl resin (B) by the method described below. It is preferable to produce the vinyl resin (B) in the presence of the polyester resin (A) from the viewpoint of achieving both grindability and hot offset properties, since the vinyl resin (B) can be uniformly crosslinked in the polyester resin (A). The binder for an image-forming material of the present invention may contain resins other than the polyester resin (A) and the vinyl resin (B) and known additives (such as a release agent).

[0082] When the binder for an image-forming material of the present invention contains a vinyl resin (B), the weight ratio of the polyester resin (A) to the vinyl resin (B) [(A) / (B)] is preferably 50 / 50 to 90 / 10 in terms of achieving both low-temperature fixability, hot offset resistance, and heat-resistant storage stability.

[0083] It is preferable that the binder for image-forming material of the present invention satisfies the following relational formula (1) from the viewpoint of low-temperature fixing property and hot offset resistance. By satisfying the relational formula (1), the compatibility of the polyester resin (A) and the vinyl resin (B) is improved, and a sufficient fixing region is secured. In order to satisfy the relational formula (1), it is sufficient to make the SP values ​​of the polyester resin (A) and the vinyl resin (B) close to each other, and it is particularly necessary to consider the weight ratio of the monomer (b) used in the vinyl resin (B). Specifically, the weight ratio of acrylonitrile (SP value: 14.4) and acrylic acid (SP value: 14.0), which are monomers (b) having a higher SP value than the polyester resin (A), and styrene (SP value: 10.6), butyl acrylate (SP value: 9.8), and ethyl acrylate (SP value: 10.2), which are monomers (b) having a lower SP value than the polyester resin (A), is considered. Relationship (1): |SP(A)-SP(B)|≦1.3(cal / cm 3 ) 0.5

[0084] In the relational formula (1), SP(A) is the solubility parameter (SP value) of the polyester resin (A), and SP(B) is the SP value of the vinyl resin (B).

[0085] The glass transition temperature (Tg) of the binder for the image-forming material of the present invention is preferably from 50 to 70°C. When the Tg of the binder for image-forming materials is 70° C. or less, the low-temperature fixability is good, and when it is 50° C. or more, the heat-resistant storage stability is good. The glass transition temperature (Tg) is measured by the method (DSC method) specified in ASTM D3418-82 using, for example, DSC Q20 manufactured by TA Instruments Co., Ltd.

[0086] When the binder for the image-forming material of the present invention contains the vinyl resin (B), the glass transition temperature (Tg A ) and the glass transition temperature (Tg B ) difference [(Tg A )-(Tg B From the viewpoint of low-temperature fixability, it is preferable that the difference between the glass transition temperatures is 15° C. or more. The greater the difference between the glass transition temperatures, the easier it is to improve the low-temperature fixability, and the reason for this will be explained below. The viscosity of the binder for the image forming material is the governing factor for low-temperature fixability. On the other hand, when comparing the viscosities of polyester resin (A) and vinyl resin (B), vinyl resin (B) has a higher viscosity. The glass transition temperature (Tg B By lowering the temperature, the viscosity of the vinyl resin (B) in the fixing temperature range can be lowered, and the viscosity of the binder for the image-forming material can be lowered. In addition, since the vinyl resin (B) contains the multifunctional vinyl monomer (a), it has a crosslinked structure, and therefore satisfies the heat resistance storage stability even though the glass transition temperature is low. In order to satisfy this range, it is particularly preferable to lower the glass transition temperature of the vinyl resin (B), and this can be controlled by including monomers having lower glass transition temperatures than the polyester resin (A), such as trimethylolpropane triacrylate (glass transition temperature of homopolymer of monomer: 10°C), butyl acrylate (glass transition temperature of homopolymer of monomer: -17°C), and ethyl acrylate (glass transition temperature of homopolymer of monomer: 11°C).

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

[0088] The binder for the image-forming material of the present invention may contain a THF-insoluble component. The content (wt %) of THF insoluble matter in the binder for image-forming material of the present invention is preferably 50 wt % or less, more preferably 5 to 30 wt %, from the viewpoint of achieving both hot offset resistance and low-temperature fixability.

[0089] The content (wt %) of the THF insoluble matter in the binder for the image-forming material of the present invention was determined by the following method. Add 50 mL of THF to 0.5 g of sample and stir under reflux for 3 hours. After cooling, filter out the insoluble matter with 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 the weight of the THF insoluble matter, and the weight obtained by subtracting the weight of the THF insoluble matter from the weight of the sample is the weight of the THF soluble matter, and calculate the weight percentages of the THF insoluble matter and the THF soluble matter.

[0090] A method for producing a binder for an image-forming material will be described. The binder for image-forming materials is not particularly limited as long as it contains polyester resin (A). For example, the method of mixing the polyester resin (A), the polyester resin (C) if necessary, the vinyl resin (B) and additives may be a commonly used known method, and examples of the mixing method include powder mixing, melt mixing, and solvent mixing. In addition, the polyester resin (A), the polyester resin (C) if necessary, the vinyl resin (B) and additives may be mixed at the same time when the binder for image-forming materials is produced. Among these methods, melt mixing is preferred because it allows uniform mixing and does not require solvent removal.

[0091] Examples of a mixer for powder mixing include a Henschel mixer, a Nauta mixer, and a Banbury mixer, with a Henschel mixer being preferred. Examples of mixing devices for melt mixing include batch mixing devices such as reaction tanks and continuous mixing devices. Continuous mixing devices are preferred for uniform mixing in a short time at an appropriate temperature. Examples of continuous mixing devices include static mixers, extruders, continuous kneaders, and three-roll machines.

[0092] Examples of the solvent mixing method include a method in which a resin such as the polyester resin (A) is dissolved in a solvent (ethyl acetate, THF, acetone, etc.), homogenized, and then the solvent is removed and pulverized; and a method in which a resin such as the polyester resin (A) is dissolved in a solvent (ethyl acetate, THF, acetone, etc.), dispersed in water, and then granulated and the solvent is removed.

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

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

[0095] As the colorant, all of the dyes and pigments used as binders for image-forming materials can be used. For example, carbon black, iron black, Sudan Black SM, Fast Yellow G, Benzidine Yellow, Pigment Yellow, India Fast Orange, Irgasin 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, Orazol Brown B, and Oil Pink OP can be mentioned, and the colorant may be a single one or a mixture of two or more kinds. In addition, if necessary, magnetic powder (powder of ferromagnetic metals such as iron, cobalt, nickel, etc., or compounds such as magnetite, hematite, and ferrite) can be contained to function as a colorant.

[0096] The release agent preferably has a flow softening point (T1 / 2) of 50 to 170°C as measured by a flow tester. Examples of the release agent include aliphatic hydrocarbon waxes such as low molecular weight polypropylene, low molecular weight polyethylene, low molecular weight polypropylene-polyethylene copolymers, polyolefin wax, microcrystalline wax, paraffin wax, and Fischer-Tropsch wax, and oxides thereof; carnauba wax, montan wax, sazol wax, and deacidified waxes thereof; 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. <How to measure flow softening point (T1 / 2)> Using a descending flow tester [e.g., CFT-500D, manufactured by Shimadzu Corporation], 1 g of the measurement sample is heated at a heating rate of 6°C / min while applying a load of 1.96 MPa with the plunger and extruding it from a nozzle with a diameter of 1 mm and a length of 1 mm. A graph of "plunger descending amount (flow value)" versus "temperature" is then drawn, and the temperature corresponding to 1 / 2 of the maximum value of the plunger descending amount is read from the graph. This value (the temperature when half of the measurement sample has flowed out) is taken 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 thermally degradable polyolefins], oxides of olefin (co)polymers with oxygen and / or ozone, maleic acid modified products of olefin (co)polymers [e.g., products modified with maleic acid and its derivatives (maleic anhydride, monomethyl maleate, monobutyl maleate, dimethyl maleate, etc.)], copolymers of olefins and unsaturated carboxylic acids [(meth)acrylic acid, itaconic acid, maleic anhydride, etc.] and / or unsaturated carboxylic acid alkyl esters [(meth)acrylic acid alkyl (C1-18 alkyl) esters and maleic acid alkyl (C1-18 alkyl) esters, etc.], and Sasol wax.

[0099] The higher alcohol is an aliphatic alcohol having 30 to 50 carbon atoms, for example, triacontanol. The fatty acid is an aliphatic alcohol having 30 to 50 carbon atoms, for example, triacontanol.

[0100] Examples of the charge control agent include nigrosine dyes, triphenylmethane dyes containing a tertiary amine as a side chain, quaternary ammonium salts, polyamine resins, imidazole derivatives, polymers containing a quaternary ammonium base, metal-containing azo dyes, copper phthalocyanine dyes, metal salicylic acid salts, boron complexes of benzilic acid, sulfonic acid group-containing polymers, fluorine-containing polymers, and halogen-substituted aromatic ring-containing polymers.

[0101] Examples of the fluidizing agent include colloidal silica, alumina powder, titanium oxide 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 content of the colorant is preferably 1 to 30% by weight, and more preferably 3 to 10% by weight, based on the weight of the toner. The content of the release agent is preferably 1 to 10% by weight based on the weight of the toner. The content of the charge control agent is preferably 0.5 to 7.5% by weight based on the weight of the toner. The content of the fluidizing agent is preferably 0.1 to 4% by weight based on the weight of the toner. The total content of the additives is preferably 2.6 to 31.6% by weight based on the toner weight. By setting the composition ratio of the toner in the above range, a toner having good hot offset resistance, heat-resistant storage stability and image stability can be easily obtained.

[0103] The toner may be obtained by any of the known methods such as a kneading and pulverizing method, an emulsion phase inversion method, and a polymerization method. For example, when a toner is obtained by a kneading and pulverizing method, the components constituting the toner except for the fluidizing agent are dry-blended, melt-kneaded, then coarsely pulverized, and finally, the toner is pulverized using a jet mill pulverizer or the like, and further classified to obtain fine particles having a volume average particle size (D50) of preferably 5 to 20 μm, and then the fluidizing agent is mixed therein to produce the toner. The volume average particle size (D50) is measured using a Coulter counter (for example, trade name: Multisizer III [manufactured by Beckman Coulter, Inc.]).

[0104] In addition, when the toner is obtained by the emulsion phase inversion method, the components constituting the toner except for the fluidizing agent are dissolved or dispersed in an organic solvent, and then emulsified by adding water or the like, followed by separation and classification to produce the toner. The volume average particle size of the toner is preferably 3 to 15 μm.

[0105] The toner is mixed with carrier particles such as iron powder, glass beads, nickel powder, ferrite, magnetite, and ferrite coated with resin (acrylic resin, silicone resin, etc.) as necessary, and used as a developer for an electric latent image. When carrier particles are used, the weight ratio of the toner to the carrier particles is preferably 1 / 99 to 99 / 1. Also, the toner can be rubbed against a member such as a charging blade instead of the carrier particles to form an electric latent image. The toner does not necessarily need to contain carrier particles.

[0106] The toner is fixed to a support (paper, polyester film, etc.) to form a recording material by a copier, printer, etc. As a method for fixing to a support, a known hot roll fixing method, flash fixing method, etc. can be used.

[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, etc. More specifically, it is used for developing electrostatic images or magnetic latent images that are particularly suitable for full color.

[0108] The present specification discloses the following:

[0109] The present disclosure (1) relates to a binder for an image-forming material, comprising a polyester resin (A) obtained by polycondensing an alcohol component and a carboxylic acid component, the polyester resin (A) containing 25 to 60 mol % of ethylene glycol based on the total number of moles of the alcohol component, and containing 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 11.5 (cal / cm 3 ) 1 / 2and the polyester resin (A) has an acid value of 15 mgKOH / g or less.

[0110] The present disclosure (2) is the binder for an image-forming material according to the present disclosure (1), wherein the polyester resin (A) has a calcium element content of 10 to 4000 ppm as measured by fluorescent X-ray.

[0111] The present disclosure (3) is the binder for an image-forming material according to the present disclosure (1) or (2), wherein the flow softening point (° C.) of the polyester resin (A) is 120° C. or lower. EXAMPLES

[0112] The present invention will be further described below with reference to examples and comparative examples, but the present invention is not limited to these.

[0113] <Production Example 1> [Production of polyester resin (A1)] In a pressurizable reaction vessel, 68 parts by weight (40.7 mol%) of ethylene glycol and 412 parts by weight of recycled PET resin (corresponding to 71.5 mol% ethylene glycol and 83 mol% terephthalic acid) were placed, and depolymerization reaction (closed transesterification reaction) was carried out at 220°C for 2 hours with stirring to obtain a depolymerized product after the reaction. Next, the depolymerized product was cooled to 180°C, and 531 parts by weight (56.6 mol%) of bisphenol A·PO 2-mol adduct, 97 parts by weight (15 mol%) of dodecenyl succinic anhydride, and 2 parts by weight of titanium diisopropoxy bis(triethanolamine) as a condensation catalyst were placed, and the temperature was raised to 220°C while the pressure was reduced under a reduced pressure of 0.5 to 2.5 kPa to remove 115 parts by weight (68.7 mol%) of ethylene glycol, and the product was cooled to 175°C when the peak top molecular weight reached 6000. Next, 11 parts by weight (2 mol%) of trimellitic anhydride was added, and esterification at normal pressure at 175°C for 1 hour was performed, followed by removal to obtain polyester resin (A1). 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.

[0114] <Production Example 2> [Production of polyester resin (A2)] In a pressurizable reaction vessel, 308 parts by weight of recovered PET resin (equivalent to 60.5 mol% ethylene glycol, 71 mol% terephthalic acid), 591 parts by weight (71.3 mol%) of bisphenol A·PO 2-mol adduct, 145 parts by weight (27 mol%) of dodecenyl succinic anhydride, and 2 parts by weight of titanium diisopropoxy bis (triethanolamine) as a condensation catalyst were placed, and while heating to 220 ° C, the pressure was reduced to 0.5 to 2.5 kPa to remove 47 parts by weight (31.8 mol%) of ethylene glycol, and when the peak top molecular weight reached 6300, it was cooled to 175 ° C. Next, 9 parts by weight (2 mol%) of trimellitic anhydride was placed, and esterification at normal pressure at 175 ° C for 1 hour was performed, followed by removal to obtain polyester resin (A2).

[0115] <Production Example 3> [Production of polyester resin (A3)] In a pressurizable reaction vessel, 91 parts by weight (47.6 mol%) of ethylene glycol and 520 parts by weight of recycled PET resin (corresponding to 79.0 mol% ethylene glycol and 89 mol% terephthalic acid) were placed, and depolymerization reaction (closed transesterification reaction) was carried out at 220°C for 2 hours with stirring to obtain a depolymerized product after the reaction. Next, the depolymerized product was cooled to 180°C, and 444 parts by weight (41.4 mol%) of bisphenol A·PO 2-mol adduct, 67 parts by weight (9 mol%) of dodecenyl succinic anhydride, and 2 parts by weight of titanium diisopropoxy bis(triethanolamine) as a condensation catalyst were placed, and the temperature was raised to 220°C while the pressure was reduced under a reduced pressure of 0.5 to 2.5 kPa to remove 130 parts by weight (68.0 mol%) of ethylene glycol. When the peak top molecular weight reached 6400, the product was cooled to 175°C. Next, 9 parts by weight (2 mol %) of trimellitic anhydride was added, and esterification was carried out at normal pressure at 175° C. for 1 hour, and then the contents were discharged to obtain a polyester resin (A3).

[0116] <Production Example 4> [Production of polyester resin (A4)] In a pressurizable reaction vessel, 67 parts by weight (40.7 mol%) of ethylene glycol and 407 parts by weight of recycled PET resin (corresponding to 71.8 mol% ethylene glycol and 80 mol% terephthalic acid) were placed, and depolymerization reaction (closed transesterification reaction) was carried out at 220°C for 2 hours with stirring to obtain a depolymerized product after the reaction. Next, the depolymerized product was cooled to 180°C, and 524 parts by weight (56.7 mol%) of bisphenol A·PO 2-mol adduct, 96 parts by weight (15 mol%) of dodecenyl succinic anhydride, and 2 parts by weight of titanium diisopropoxy bis(triethanolamine) as a condensation catalyst were placed, and the temperature was raised to 220°C while the pressure was reduced under a reduced pressure of 0.5 to 2.5 kPa to remove 114 parts by weight (69.3 mol%) of ethylene glycol, and the product was cooled to 175°C when the peak top molecular weight reached 6100. Next, 24 parts by weight (5 mol %) of trimellitic anhydride was added, and esterification was carried out at normal pressure at 175° C. for 1 hour, and then the contents were discharged to obtain a polyester resin (A4).

[0117] <Production Example 5> [Production of polyester resin (A5)] In a pressurizable reaction vessel, 68 parts by weight (40.7 mol%) of ethylene glycol and 411 parts by weight of recycled PET resin (corresponding to 71.5 mol% ethylene glycol and 83 mol% terephthalic acid) were placed, and depolymerization reaction (closed transesterification reaction) was carried out at 220°C for 2 hours with stirring to obtain a depolymerized product after the reaction. Next, the depolymerized product was cooled to 180°C, and 530 parts by weight (56.6 mol%) of bisphenol A·PO 2-mol adduct, 97 parts by weight (15 mol%) of dodecenyl succinic anhydride, and 2 parts by weight of titanium diisopropoxy bis(triethanolamine) as a condensation catalyst were placed, and the temperature was raised to 220°C while the pressure was reduced to 0.5 to 2.5 kPa to remove 115 parts by weight (68.7 mol%) of ethylene glycol. When the peak top molecular weight reached 6000, the product was cooled to 175°C. Next, 11 parts by weight (2 mol %) of trimellitic anhydride and 2 parts by weight of calcium carbonate were added, and esterification was carried out at normal pressure at 175° C. for 1 hour, and then the contents were taken out to obtain a polyester resin (A5).

[0118] <Production Example 6> [Production of polyester resin (A6)] In a pressurizable reaction vessel, 68 parts by weight (40.9 mol%) of ethylene glycol and 410 parts by weight of recycled PET resin (equivalent to 71.6 mol% ethylene glycol, 81 mol% terephthalic acid) were placed, and depolymerization reaction (closed transesterification reaction) was carried out at 220°C for 2 hours with stirring to obtain a depolymerized product after the reaction. Next, the depolymerized product was cooled to 180°C, and 529 parts by weight (56.7 mol%) of bisphenol A·PO 2-mol adduct, 96 parts by weight (15 mol%) of dodecenyl succinic anhydride, and 2 parts by weight of titanium diisopropoxy bis(triethanolamine) as a condensation catalyst were placed, and the temperature was raised to 220°C while the pressure was reduced under a reduced pressure of 0.5 to 2.5 kPa to remove 115 parts by weight (69.1 mol%) of ethylene glycol, and the product was cooled to 175°C when the peak top molecular weight reached 6100. Next, 16 parts by weight (4 mol %) of trimellitic anhydride was added, and esterification was carried out at normal pressure at 175° C. for 1 hour, and then the contents were discharged to obtain a polyester resin (A6).

[0119] <Comparative Production Example 1> [Production of polyester resin (A'1)] In a pressurizable reaction vessel, 84 parts by weight (48.5 mol%) of ethylene glycol and 512 parts by weight of recovered PET resin (equivalent to 85.9 mol% ethylene glycol, 97.6 mol% terephthalic acid) were placed, and depolymerization reaction (closed transesterification reaction) was carried out at 220 ° C for 2 hours while stirring, to obtain a depolymerized product after the reaction. Next, the depolymerized product was cooled to 180 ° C, and 547 parts by weight (56.3 mol%) of bisphenol A·PO 2-mol adduct and 2 parts by weight of titanium diisopropoxy bis (triethanolamine) as a condensation catalyst were placed, and while heating to 220 ° C, 157 parts by weight (90.7 mol%) of ethylene glycol was removed by reducing the pressure under a reduced pressure of 0.5 to 2.5 kPa, and when the peak top molecular weight reached 6000, it was cooled to 175 ° C. Next, 11 parts by weight (2.4 mol%) of trimellitic anhydride was placed, and esterification at normal pressure at 175 ° C for 1 hour was carried out, and then the polyester resin (A'1) was obtained by removing it.

[0120] <Comparative Production Example 2> [Production of polyester resin (A'2)] In a pressurizable reaction vessel, 244 parts by weight of recovered PET resin (equivalent to 53.3 mol% ethylene glycol, 64 mol% terephthalic acid), 646 parts by weight (86.6 mol%) of bisphenol A·PO 2-mol adduct, 162 parts by weight (33 mol%) of dodecenyl succinic anhydride, and 2 parts by weight of titanium diisopropoxy bis (triethanolamine) as a condensation catalyst were placed, and while heating to 220 ° C, the pressure was reduced to 0.5 to 2.5 kPa to remove 53 parts by weight (39.9 mol%) of ethylene glycol, and when the peak top molecular weight reached 6300, it was cooled to 175 ° C. Next, 9 parts by weight (3 mol%) of trimellitic anhydride was placed, and esterification at normal pressure at 175 ° C for 1 hour was performed, followed by removal to obtain polyester resin (A'2).

[0121] <Comparative Production Example 3> [Production of polyester resin (A'3)] In a pressurizable reaction vessel, 106 parts by weight (53.7 mol%) of ethylene glycol and 559 parts by weight of recycled PET resin (equivalent to 82.2 mol% ethylene glycol and 92 mol% terephthalic acid) were placed, and depolymerization reaction (closed transesterification reaction) was carried out at 220°C for 2 hours with stirring to obtain a depolymerized product after the reaction. Next, the depolymerized product was cooled to 180°C, and 427 parts by weight (38.5 mol%) of bisphenol A·PO 2-mol adduct, 46 parts by weight (6 mol%) of dodecenyl succinic anhydride, and 2 parts by weight of titanium diisopropoxy bis(triethanolamine) as a condensation catalyst were placed, and the temperature was raised to 220°C while the pressure was reduced under a reduced pressure of 0.5 to 2.5 kPa to remove 147 parts by weight (74.4 mol%) of ethylene glycol, and the mixture was cooled to 175°C when the peak top molecular weight reached 6400. Next, 9 parts by weight (2 mol %) of trimellitic anhydride was added, and esterification was carried out at normal pressure at 175° C. for 1 hour, and then the contents were discharged to obtain a polyester resin (A′3).

[0122] <Comparative Production Example 4> [Production of polyester resin (A'4)] In a pressure-applicable reaction vessel, 67 parts by weight (40.7 mol%) of ethylene glycol and 405 parts by weight of recycled PET resin (equivalent to 71.4 mol% of ethylene glycol and 80 mol% of terephthalic acid) were put in, and a depolymerization reaction (closed transesterification reaction) was carried out at 220°C for 2 hours while stirring to obtain a depolymerized product after the reaction. Next, the depolymerized product was cooled to 180°C, 523 parts by weight (56.5 mol%) of bisphenol A·PO 2 mol adduct, 95 parts by weight (14 mol%) of dodecenyl succinic anhydride, and 2 parts by weight of titanium diisopropoxybis(triethanolamineate) as a condensation catalyst were put in, and while raising the temperature to 220°C, the pressure was reduced under a reduced pressure of 0.5 to 2.5 kPa to remove 113 parts by weight (68.6 mol%) of ethylene glycol. When the peak top molecular weight reached 6400, it was cooled to 175°C. Next, 27 parts by weight (6 mol%) of trimellitic anhydride was put in, and after esterification at normal pressure at 175°C for 1 hour, it was taken out to obtain a polyester resin (A'4).

[0123] <Comparative Production Example 5> [Production of Polyester Resin (A'5)] In a pressure-applicable reaction vessel, 136 parts by weight of recycled PET resin (equivalent to 31.8 mol% of ethylene glycol and 39 mol% of terephthalic acid), 637 parts by weight (91.1 mol%) of bisphenol A·PO 2 mol adduct, 261 parts by weight (58 mol%) of dodecenyl succinic anhydride, and 2 parts by weight of titanium diisopropoxybis(triethanolamineate) as a condensation catalyst were put in, and while raising the temperature to 220°C, the pressure was reduced under a reduced pressure of 0.5 to 2.5 kPa to remove 28 parts by weight (22.9 mol%) of ethylene glycol. When the peak top molecular weight reached 6300, it was cooled to 175°C. Next, 9 parts by weight (3 mol%) of trimellitic anhydride was put in, and after esterification at normal pressure at 175°C for 1 hour, it was taken out to obtain a polyester resin (A'5).

[0124] The compositions and physical property values of the polyester resin (A) and the comparative polyester resin (A') were described in Table 1.

[0125]

Table 1

[0126] <Production Example 7> [Production of polyester resin (C1)] In a pressurized reaction vessel equipped with a stirrer, a heating / cooling device, a thermometer, an air inlet tube, a pressure reducing device, and a water reducing device, 198 parts by weight of bisphenol A·PO 2-mol adduct, 534 parts by weight of bisphenol A·PO 3-mol adduct, 172 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 diisopropoxy bistriethanolamine was added at 120°C and homogenized for 30 minutes, and reduced pressure esterification was performed while raising the temperature to 227°C. The reduced pressure esterification was performed at 227°C for 5 hours while maintaining a pressure of 4kPa or less, and it was confirmed that the acid value was 1mgKOH / g or less. Then, it was cooled to 180°C, 79 parts by weight of trimellitic anhydride was added, and after esterification reaction at normal pressure for 1 hour, the temperature was reduced and raised to 205°C, and reduced pressure esterification was performed at 205°C. When the flow softening point reached 140°C, it was taken out to obtain polyester resin (C1).

[0127] Table 2 shows the composition and physical properties of the polyester resin (C).

[0128] [Table 2]

[0129] <Example 1> [Production of toner (T1)] Using a Henschel mixer [FM10B manufactured by Mitsui Miike Chemical Engineering Co., Ltd.], polyester resin (A1) and polyester resin (C1) were premixed according to the compounding ratio (parts by weight) in Table 3 to obtain a binder for image-forming materials. Next, the binder for image-forming materials was premixed with a colorant, a release agent, and a charge control agent, and then kneaded with a twin-screw kneader [PCM-30 manufactured by Ikegai Corporation]. Then, the mixture was finely pulverized using a supersonic jet pulverizer Labjet [manufactured by Nippon Pneumatic Industrial Co., Ltd.], and classified with an air classifier [MDS-I manufactured by Nippon Pneumatic Industrial Co., Ltd.] to obtain toner particles with a particle size D50 of 7 μm. Next, 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 using a sample mill to obtain a toner (T1).

[0130] The colorants, release agents and charge control agents in Table 3 are as follows: Colorant: Carbon black MA-100 [Mitsubishi Chemical Co., Ltd.] Release agent: Carnauba wax [Toyo Adle Co., Ltd.] Charge control agent: T-77 [Hodogaya Chemical Co., Ltd.]

[0131] <Examples 2 to 6> [Production of Toners (T2) to (T6)] The binder for image-forming materials and the toner were prepared in the same manner as in Example 1, except that the compounding ratio (parts by weight) in Table 3 was followed, to obtain toners (T2) to (T6).

[0132] <Comparative Examples 1 to 5> [Production of Toners (T'1) to (T'5)] Binders for image-forming materials and toners were prepared in the same manner as in Example 1, except that the compounding ratios (parts by weight) in Table 3 were followed, to obtain toners (T'1) to (T'5).

[0133] [Evaluation method] The measurement and evaluation methods for the low temperature fixing property, hot offset resistance, heat resistance storage stability, image quality stability and hydrolysis resistance of the obtained toners (T1) to (T6) and (T'1) to (T'5) will be described below, including the criteria for judgment.

[0134] <Low temperature fixability> Toner is applied to the paper at 1.00 mg / cm 2 The powder was applied evenly to the paper surface using a printer without a heat fixing unit. This paper was passed through a soft roller at a fixing speed (circumferential speed of the heating roller) of 213 mm / sec and at heating roller temperatures ranging from 100 to 200°C in 5°C increments. Next, the fixed image was visually inspected for the presence or absence of cold offset, and the temperature at which cold offset occurs (MFT) was measured. The lower the temperature at which cold offset occurs, the better the low-temperature fixing ability. Under these evaluation conditions, it is generally preferable that the MFT is 125° C. or lower.

[0135] <Hot offset resistance> Using the same method as described above for low-temperature fixability, the toner was placed on the paper and the paper was passed through a soft roller at a fixing speed (circumferential speed of the heating roller) of 213 mm / sec and at heating roller temperatures ranging from 100 to 200°C in 5°C increments. Next, the presence or absence of hot offset on the fixed image was visually observed, and the temperature at which the hot offset occurred was measured. The higher the temperature at which hot offset occurs, the better the hot offset resistance. In this evaluation condition, a temperature of 180° C. or higher is preferable.

[0136] <Heat-resistant storage stability> 1 g of toner and 0.013 g of Aerosil R972 (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 cohesion was then measured using a powder tester, and the heat resistance storage stability was evaluated. The lower the value in the cohesion test determined by the following method, the more excellent the heat-resistant storage stability. Under these evaluation conditions, a value of 5% or less is preferable. Equipment: POWDER TESTER model PT-X (manufactured by Hosokawa Micron) Sieve openings: 355μm, 250μm, 150μm Vibration width: 1mm Vibration duration: 30 seconds Operation method: Set the sieves on the vibration table of the powder tester in the following order: top 355μm, middle 250μm, bottom 150μm. Place 1g of toner on the top sieve and vibrate with a vibration amplitude of 1mm for 30 seconds. Measure the weight of toner remaining on each sieve. Cohesion: Calculated from the weight of toner used for measurement and the weight of toner remaining after sieving. Cohesion degree (%)=(U / N+M / N×3 / 5+L / N×1 / 5)×100 U: weight of top row, M: weight of middle row, L: weight of bottom row, N: weight of sample (1g)

[0137] <Image quality stability> A two-component developer was prepared by uniformly mixing 30 g of toner and 800 g of ferrite carrier (f-150, Powdertech Co., Ltd.). Using this developer, an unfixed image developed using a commercially available copier [AR5030, Sharp Co., Ltd.] was fixed at a process speed of 80 mm / sec using the fixing unit of a commercially available full-color copier [LBP-2160, Canon Inc.]. [Evaluation Criteria] ◎: Image quality remains good even after 8,000 continuous copies ○: After 8,000 continuous copies, there is a slight decrease in image quality (white background stains). △: After 8,000 continuous copies, the image quality is clearly degraded, with white lines appearing in the image in addition to white background stains. Under these conditions, it is preferable that the rating is 0 or higher.

[0138] <Hydrolysis resistance> 1 g of the toner was placed in a glass container without a lid, and left to stand for 10 days in an atmosphere at a temperature of 95°C and a relative humidity of 95%. The weight average molecular weight and the storage modulus (Pa) at 100°C were measured by GPC before and after the test to confirm the changes in the weight average molecular weight and the storage modulus, and to evaluate whether hydrolysis had occurred. The GPC measurement and the storage modulus (Pa) at 100°C were measured in the same manner as for polymer (A). ◎: Changes in weight average molecular weight and storage modulus are both less than ±5% ○: The change in weight average molecular weight is ±5% or more, but the change in storage elasticity is less than ±5% △: Weight average molecular weight and elastic modulus both change by ±5% or more In this evaluation condition, a rating of 0 or higher is preferable.

[0139] [Table 3]

[0140] As is clear from the evaluation results in Table 3, all of the toners (T1) to (T6) according to the examples obtained excellent results in all performance evaluations. On the other hand, the toners (T'1) to (T'5) according to the comparative examples were poor in some performance items. [Industrial Applicability]

[0141] The binder for an image-forming material of the present invention has excellent heat resistance storage stability, image quality stability and hydrolysis resistance while maintaining low-temperature fixing property and hot offset resistance, and can be suitably used as a toner for developing electrostatic images used in electrophotography, electrostatic recording, electrostatic printing, etc. Further, the composition is suitable for use as an inkjet binder, a paint additive, an adhesive additive, particles for electronic paper, and the like.

Claims

1. A binder for an image-forming material, comprising a polyester resin (A) obtained by polycondensing an alcohol component and a carboxylic acid component, the binder comprising: 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 11.5 (cal / cm ３ ) １／２ and the acid value of the polyester resin (A) is 15 mgKOH / g or less.

2. 2. The binder for image-forming materials according to claim 1, wherein the calcium element content is 10 to 4000 ppm based on the weight of said polyester resin (A) as measured by fluorescent X-rays.

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

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