Binder for image forming material

Abstract

To provide a binder for image forming material that is excellent in low temperature fixability, hot offset resistance, humidity and heat-resistant storage property, and colorant dispersion properties.SOLUTION: A binder for image forming material includes a polyester resin (A) obtained through polycondensation of an alcohol component and a carboxylic acid component, and a polyester resin (B). The polyester resin (A) includes 28-88 mol% of ethylene glycol on the basis of the total number of moles of the alcohol component, and includes 55-99 mol% of terephthalic acid on the basis of the total number of moles of the carboxylic acid component. The flow softening point of the polyester resin (A) is 90-125°C. The flow softening point of the polyester resin (B) is 126-160°C. The water content in the binder for image forming material after a 24-hour moisture absorption test at a temperature of 50°C and a relative humidity of 80%, is 2000-9000 ppm.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] In recent years, advances in electrophotography have led to efforts to expand the application of electrophotography to commercial and industrial printing. Commercial and industrial printing require stable, high-speed printing, which requires a certain level of low-temperature fixability and hot offset resistance, i.e., a wide fixation range. Other requirements include durability against shear and compression caused by agitation within the toner cartridge to prevent the generation of fine powder, and maintaining charging performance to enable stable mass printing of images of the same quality. The image forming material used in the toner etc. has a significant effect on the toner properties as described above, and known materials include polystyrene resin, styrene-acrylic resin, polyester resin, epoxy resin, polyurethane resin, polyamide resin, etc., but polyester resin has attracted particular attention because it is easy to achieve a balance between fixability and chargeability. For example, a toner binder that has excellent fixing and charging properties and contains a polyester resin containing an aliphatic diol having 2 to 4 carbon atoms as a main component has been disclosed (Patent Documents 1 and 2). However, it cannot be said that they have sufficient chargeability, wide fixing width, pulverizability, and abrasion resistance to be used as toners for commercial printing and industrial printing, and improvements in these areas are desired. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-141966 [Patent Document 2] Japanese Patent Application Publication No. 9-278873 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a binder for an image-forming material that is excellent in low-temperature fixability, hot offset resistance, humidity and heat resistance storage stability, and colorant dispersibility. [Means for solving the problem]

[0005] The present inventors have conducted extensive research and have arrived at the present invention. That is, the present invention provides a binder for an image-forming material, which comprises a polyester resin (A) and a polyester resin (B) obtained by polycondensation of an alcohol component and a carboxylic acid component, wherein the polyester resin (A) contains 28 to 88 mol % of ethylene glycol based on the total number of moles of the alcohol components, and 55 to 99 mol % of terephthalic acid based on the total number of moles of the carboxylic acid components, the polyester resin (A) has a flow softening point of 90°C to 125°C, and the polyester resin (B) has a flow softening point of 126°C to 160°C, and the moisture content after a 24-hour moisture absorption test at a temperature of 50°C and a relative humidity of 80% is 2000 to 9000 ppm. [Effects of the Invention]

[0006] According to the present invention, it is possible to provide a binder for an image-forming material that is excellent in low-temperature fixability, hot offset resistance, humidity and heat resistance storage stability, and colorant dispersibility. DETAILED DESCRIPTION OF THE INVENTION

[0007] The binder for the image-forming material of the present invention will be described in detail below.

[0008] The binder for the image-forming material of the present invention contains a polyester resin (A) and a polyester resin (B).

[0009] The polyester resin (A) is a polyester resin obtained by polycondensation of an alcohol component and a carboxylic acid component.

[0010] The alcohol component includes a diol (x2) and a trihydric or higher polyol (x3), which may be used alone or in combination of two or more.

[0011] Examples of the diol (x2) include alkylene glycols having 2 to 36 carbon atoms (ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, pentyl glycol, 1,5-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), alkylene ether glycols having 6 to 36 carbon atoms (diethylene glycol, Examples of suitable alkylene compounds include alicyclic diols having 6 to 36 carbon atoms (1,4-cyclohexanedimethanol, hydrogenated bisphenol A, etc.), (poly)alkylene oxide adducts of the above-mentioned alicyclic diols (preferably having an average number of moles added of 1 to 30), aromatic diols [monocyclic dihydric phenols (e.g., hydroquinone, etc.) and bisphenols, etc.] and alkylene oxide adducts of the above-mentioned aromatic diols (preferably having an average number of moles added of 2 to 30).

[0012] The alkylene oxide adducts of the bisphenols can be obtained by adding alkylene oxide (hereinafter, "alkylene oxide" may be abbreviated as AO) to the bisphenols.

[0013] Examples of bisphenols include those represented by the following general formula (1). 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.]

[0014] Specific examples of bisphenols include bisphenol A, bisphenol F, bisphenol B, bisphenol E, 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 also be used in combination.

[0015] Examples of alkylene oxides to be added to bisphenols include alkylene oxides having 2 to 30 carbon atoms, such as ethylene oxide (hereinafter, "ethylene oxide" may be abbreviated as EO), propylene oxide (hereinafter, "propylene oxide" may be abbreviated as PO), butylene oxide, tetrahydrofuran, and combinations of two or more of these.

[0016] Of these diols (x2), from the viewpoints of low-temperature fixability and heat-resistant storage stability, alkylene glycols having 2 to 36 carbon atoms and alkylene oxide adducts of aromatic diols are preferred, alkylene glycols having 4 to 10 carbon atoms and alkylene oxide adducts of bisphenols (average number of added moles is preferably 2 to 5) are more preferred, alkylene glycols having 2 to 6 carbon atoms and alkylene oxide adducts of bisphenol A (average number of added moles is preferably 2 to 5) are even more preferred, and ethylene glycol and EO and / or PO adducts of bisphenol A (average number of added moles is preferably 2 to 3) are particularly preferred.

[0017] Furthermore, the alcohol component constituting the polyester resin (A) preferably contains an alkylene oxide adduct of bisphenol A, and more preferably contains an EO and / or PO adduct of bisphenol A (the average number of moles added is preferably 2 to 3). When the alcohol component constituting the polyester resin (A) contains an alkylene oxide adduct of bisphenol A, the humidity and heat resistant storage stability of the toner is improved compared to when it does not contain this adduct.

[0018] Examples of the trivalent or higher polyol (x3) include aliphatic polyhydric alcohols having 3 to 36 carbon atoms and having a valence of 3 or more, sugars and derivatives thereof, alkylene oxide adducts of aliphatic polyhydric alcohols (the average number of moles added is preferably 1 to 30), alkylene oxide adducts of trisphenols (trisphenol PA, etc.) (the average number of moles added is preferably 2 to 30), and alkylene oxide adducts of novolak resins (including phenol novolak and cresol novolak, etc., having an average degree of polymerization of preferably 3 to 60) (the average number of moles added is preferably 2 to 30).

[0019] Examples of the aliphatic polyhydric alcohol 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. Furthermore, examples of sugars and their derivatives include sucrose and methyl glucoside.

[0020] Among these trivalent or higher polyols (x3), from the viewpoint of achieving both low-temperature fixability and hot offset resistance, preferred are trivalent or higher aliphatic polyols having 3 to 36 carbon atoms, and alkylene oxide adducts (average number of added moles is preferably 2 to 30) of novolak resins (including phenol novolak and cresol novolak, etc., with an average degree of polymerization preferably of 3 to 60), more preferred are trivalent aliphatic polyols having 3 to 8 carbon atoms, and particularly preferred is trimethylolpropane.

[0021] Furthermore, the alcohol component constituting the polyester resin (A) may contain a mono-ol component, if necessary. Examples of the mono-ol (x1) include linear or branched alkyl alcohols having 1 to 30 carbon atoms (e.g., methanol, ethanol, isopropanol, 1-decanol, dodecyl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, arachidyl alcohol, behenyl alcohol, and lignoceryl alcohol).

[0022] Of these monools (x1), from the viewpoints of image strength and heat-resistant storage stability, linear or branched alkyl alcohols having 8 to 24 carbon atoms are preferred, linear alkyl alcohols having 8 to 24 carbon atoms are more preferred, and dodecyl alcohol, stearyl alcohol, arachidyl alcohol, behenyl alcohol, and lignoceryl alcohol are even more preferred.

[0023] The carboxylic acid component includes a dicarboxylic acid (y2) and a trivalent or higher polycarboxylic acid (y3), which may be used alone or in combination of two or more.

[0024] Examples of dicarboxylic acids (y2) include aromatic dicarboxylic acids having 8 to 36 carbon atoms (such as terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid), aliphatic dicarboxylic acids having 2 to 50 carbon atoms (such as oxalic acid, malonic acid, succinic acid, adipic acid, lepargic acid, and sebacic acid), alicyclic dicarboxylic acids having 6 to 40 carbon atoms (such as dimer acids (dimerized linoleic acid)), and alkene dicarboxylic acids having 4 to 36 carbon atoms (such as alkenylsuccinic acids such as dodecenylsuccinic acid, maleic acid, fumaric acid, citraconic acid, and mesaconic acid), as well as ester-forming derivatives thereof. Here, the term "ester-forming derivatives" refers to carboxylic acid anhydrides, alkyl (such as methyl, ethyl, butyl, and stearyl having 1 to 24 carbon atoms, preferably those having 1 to 4 carbon atoms) esters, and partial alkyl esters.

[0025] Among these dicarboxylic acids (y2), from the viewpoint of achieving both low-temperature fixability, hot offset resistance, and heat-resistant storage stability, aromatic dicarboxylic acids having 8 to 36 carbon atoms, aliphatic dicarboxylic acids having 2 to 50 carbon atoms, and alkene dicarboxylic acids having 4 to 36 carbon atoms are preferred, terephthalic acid, isophthalic acid, adipic acid, succinic acid, maleic acid, and fumaric acid are more preferred, terephthalic acid, isophthalic acid, adipic acid, fumaric acid, and succinic acid are particularly preferred, and terephthalic acid, isophthalic acid, adipic acid, and succinic acid are most preferred. Furthermore, anhydrides and lower alkyl esters of these acids may also be used.

[0026] Examples of the trivalent or higher polycarboxylic acid (y3) include trivalent or higher aromatic polycarboxylic acids having 9 to 20 carbon atoms (trimellitic acid, pyromellitic acid, etc.), aliphatic (including alicyclic) tricarboxylic acids having 6 to 36 carbon atoms (hexanetricarboxylic acid, decanetricarboxylic acid, etc.), and ester-forming derivatives thereof.

[0027] Among these trivalent or higher polycarboxylic acids (y3), from the viewpoint of achieving both low-temperature fixability and hot offset resistance, aromatic polycarboxylic acids having 9 to 20 carbon atoms are preferred, and trimellitic acid and pyromellitic acid are more preferred. Furthermore, anhydrides and lower alkyl esters of these acids may also be used.

[0028] Furthermore, if necessary, a monocarboxylic acid component can be contained as a carboxylic acid component constituting the polyester resin (A). Examples of the monocarboxylic acid (y1) include aromatic monocarboxylic acids having 7 to 37 carbon atoms (such as benzoic acid, toluic acid, 4-ethylbenzoic acid, and 4-propylbenzoic acid), and aliphatic (including alicyclic) monocarboxylic acids having 2 to 50 carbon atoms (such as acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, palmitic acid, margaric acid, stearic acid, and behenic acid).

[0029] Of these monocarboxylic acids (y1), aromatic monocarboxylic acids having 7 to 37 carbon atoms are preferred, and benzoic acid is more preferred, from the viewpoints of image strength and heat-resistant storage stability.

[0030] In the present invention, the alcohol component and the carboxylic acid component constituting the polyester resin (A) may be a polyethylene terephthalate resin and a depolymerized product thereof.

[0031] Polyethylene terephthalate resin (hereinafter also referred to as PET) is, for example, a recycled PET resin, and its raw material is PET products collected from the market (hereinafter also referred to as recycled PET products), such as PET bottles and PET films.

[0032] The polyester resin (A) preferably contains calcium in the range of 100 to 4000 ppm as measured by fluorescent X-rays, from the viewpoint of the humidity and heat resistance storage stability of the toner. The calcium content in the polyester resin (A) can be determined by adjusting the amount of the calcium-containing compound added during the production of the polyester resin (A). In this specification, the quantitative determination of calcium content by fluorescent X-rays will be described below. <Sample preparation> A pressure molding method can be used to compress powders such as toner binders and toner into pellets. For example, a powder sample can be filled into the center of a 5mm thick ring made of polyvinyl chloride resin to form a slight mound, and then pressed into pellets using a press with a load of 10 tons. Care must be taken to avoid contamination with other components, especially calcium. In particular, in the case of toner, calcium may be contained in external additives, so the toner must first be ultrasonically cleaned with methanol or other cleaning agents to remove the external additives from the surface, and then surface analysis such as STEM must be performed to confirm that the external additives have been removed. This allows for accurate measurement of the calcium content. <Measurement method> It is possible to prepare a calibration curve using a standard sample with a known calcium concentration 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, 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 less accurate, so it is preferable to use the calibration curve method, which can measure calcium concentration more accurately. <Measuring equipment> For example, it can be measured using an X-ray fluorescence analyzer (Axios, manufactured by Malvern Panalytical).

[0033] The acid value of the polyester resin (A) is preferably 18 mgKOH / g or less, more preferably 0.1 to 15 mgKOH / g, and even more preferably 1 to 10 mgKOH / g, from the viewpoints of low-temperature fixability and humidity and heat resistance storage stability. The hydroxyl value of the polyester resin (A) is preferably 0 to 50 mgKOH / g, more preferably 1 to 48 mgKOH / g, and even more preferably 10 to 46 mgKOH / g, from the viewpoints of low-temperature fixability, charge retention rate, and durability of print quality. The acid value and hydroxyl value can be measured according to the method specified in JIS K0070, except that the solvent for measuring the acid value is a mixed solvent of acetone, methanol, and toluene (acetone:methanol:toluene=12.5:12.5:75), and the solvent for measuring the hydroxyl value is THF.

[0034] The glass transition temperature of the polyester resin (A) is preferably from 50 to 75°C, more preferably from 55 to 70°C, from the viewpoint of heat-resistant storage stability and low-temperature fixability. The glass transition temperature (Tg) of the polyester resin (A) and the polyester resin (B) described below can be determined by the method (DSC method) specified in ASTM D3418-82. For measuring the glass transition temperature (Tg), for example, a DSC Q20 manufactured by TA Instruments can be used. The glass transition temperature (Tg) can be measured under the following conditions. <Measurement conditions> (1) Heat from 30°C to 150°C at 20°C / min (2) Hold at 150°C for 10 minutes (3) Cool to -35°C at 20°C / min (4) Keep at -35°C for 10 minutes (5) Heat up to 150°C at 20°C / min (6) The differential scanning calorimetry curve measured in the step (5) is analyzed, and the position of the inflection point is determined as the glass transition temperature.

[0035] The weight average molecular weight of the polyester resin (A) is preferably from 3,000 to 100,000, and more preferably from 5,000 to 50,000, from the viewpoints of low-temperature fixability and humidity and heat resistance storage stability.

[0036] In the present invention, the weight average molecular weight and peak top molecular weight of the polyester resin (A) and the polyester resin (B) described below can be measured by gel permeation chromatography (GPC) under the following conditions. Device (example): Tosoh Corporation HLC-8120 Column (example): 2 TSK GEL GMH6 [Tosoh Corporation] Measurement temperature: 40℃ Sample solution: 0.25 wt% THF solution Solution injection volume: 100μL Detector: Refractive index detector Standard substance: 12 standard polystyrenes (TSK standard 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 tetrahydrofuran (THF) to a concentration of 0.25% by weight, and the insoluble matter is filtered off using a PTFE filter with an aperture of 220 nm to obtain a sample solution.

[0037] The flow softening point [T1 / 2] of the polyester resin (A) is 90 to 125°C, preferably 92 to 123°C, more preferably 95 to 120°C, and particularly preferably 97 to 118°C. If the flow softening point [T1 / 2] of (A) is less than 90°C, the hot offset resistance may deteriorate. If the flow softening point [T1 / 2] of (A) is more than 125°C, it may become difficult to achieve both low-temperature fixability and hot offset resistance. The flow softening points of the polyester resin (A) and the polyester resin (B) described below can be adjusted by controlling the molecular weight and glass transition temperature (Tg) of the polyester resin, or by changing the ratio of trivalent or higher-valent 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. The flow softening point can also be increased by increasing the number of crosslinking points. Furthermore, as the polycondensation reaction progresses and the molecular weight increases, the softening point of the polyester resin (A) rises. Therefore, by monitoring and adjusting the change in the softening point, the softening point of the polyester resin (A) can be controlled.

[0038] The method for measuring the flow softening point [T1 / 2] is described below. Using a high-speed flow tester (e.g., CFT-500D manufactured by Shimadzu Corporation), 1 g of a test sample is heated at a temperature increase rate of 6°C / min. At this time, a load of 1.96 MPa is applied by the plunger, and the sample is extruded from a nozzle 1 mm in diameter and 1 mm in length. A graph of "plunger depression (flow value)" versus "temperature" is plotted, and the temperature corresponding to half of the maximum plunger depression is taken as the flow softening point [T1 / 2].

[0039] The solubility parameter (SP value) of polyester resin (A) is 10.6 to 12.4 (cal / cm) from the viewpoints of low-temperature fixability, heat-resistant storage stability, and grindability. 3 ) 0.5 The SP(A) can be reduced by, for example, reducing the acid value of the polyester resin (A), reducing the hydroxyl value of (A), reducing the cohesive strength of (A), or increasing the weight average molecular weight of (A).

[0040] In the present invention, the SP value (cal / cm 3 ) 0.5 is a value at 25°C calculated by the method described in Robert F. Fedors et al., Polymer Engineering and Science (1974), Vol. 14, pp. 151-154.

[0041] From the viewpoint of storage stability and hydrolysis resistance under high temperature and humidity conditions, the xylene-insoluble content of the polyester resin (A) is preferably 0 to 10% by weight, more preferably 0 to 7% by weight, and even more preferably 0 to 5% by weight. The xylene-insoluble content of the polyester resin (A) can be adjusted by adjusting the amount of insoluble components such as inorganic components and the amount of tri- or higher functional alcohol and / or acid components contained in the recycled PET. The xylene-insoluble content of the polyester resin (A) is measured as follows. To prepare a sample, 1.00 g of polymer (A) was dissolved or dispersed in 100 g of xylene at a temperature equal to or higher than the peak top temperature of the endothermic peak, cooled to 25°C, centrifuged in a centrifuge, the supernatant was removed, and then the sample was dried under reduced pressure (170°C, 2 hours) to obtain a xylene-insoluble fraction. The weight of the xylene-insoluble fraction was measured to four decimal places, and the xylene-insoluble fraction of (A) was calculated using the following formula: Xylene insoluble content of polyester resin (A) (wt%) = (weight of xylene insoluble content (g) / 1.00) × 100 The conditions for centrifugation are as follows: <Centrifugation conditions> Centrifuge: H-19F (manufactured by Kokusan Co., Ltd.) Rotation speed: 4000 rpm Rotation time: 20 minutes

[0042] The difference obtained by subtracting the xylene insoluble content of the polyester resin (A) from the xylene insoluble content of the polyester resin (B) is preferably 5 to 50 percentage points, more preferably 10 to 45 percentage points, from the viewpoint of hot offset resistance. The difference (percentage points) obtained by subtracting the xylene insoluble content of polyester resin (A) from the xylene insoluble content of polyester resin (B) is calculated by subtracting the xylene insoluble content (weight %) of polyester resin (A) from the xylene insoluble content (weight %) of polyester resin (B).

[0043] The polyester resin (A) in the present invention contains 28 to 88 mol %, preferably 40 to 86 mol %, and more preferably 50 to 84 mol % of ethylene glycol based on the total number of moles of the constituent alcohol components. If the ethylene glycol content is less than 28 mol %, the colorant dispersibility will be deteriorated, and if it exceeds 88 mol %, the humidity and heat resistant storage stability will be deteriorated. The polyester resin (A) in the present invention contains alcohol components other than ethylene glycol in an amount of preferably 12 to 72 mol %, more preferably 14 to 60 mol %, and even more preferably 16 to 50 mol %, based on the total molar number of the constituent alcohol components, from the viewpoints of color dispersibility and moist heat resistance storage stability. The polyester resin (A) in the present invention contains 55 to 99 mol %, preferably 57 to 98 mol %, and more preferably 59 to 97 mol % of terephthalic acid based on the total number of moles of the constituent carboxylic acid components. If the content of terephthalic acid is less than 55 mol %, the humidity and heat resistance storage stability will deteriorate, and if it exceeds 99 mol %, the dispersibility of the colorant will deteriorate. The polyester resin (A) in the present invention contains carboxylic acid components other than terephthalic acid in an amount of preferably 1 to 45 mol %, more preferably 2 to 43 mol %, and even more preferably 3 to 41 mol %, based on the total number of moles of the carboxylic acid components constituting the polyester resin (A), from the viewpoints of color dispersibility and humidity and heat resistance storage stability.

[0044] The reaction ratio of the alcohol component to the carboxylic acid component, expressed as the molar ratio of hydroxyl groups to carboxyl groups {[OH] / [COOH]}, 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, from the viewpoint of humidity and heat resistance storage stability.

[0045] The method for producing the polyester resin (A) will be described. The polyester resin (A) can be obtained by carrying out a polycondensation reaction between an alcohol component and a carboxylic acid component in the presence of a polymerization catalyst.

[0046] Specifically, the polyester resin (A) can be produced, for example, as follows: For example, an alcohol component and a carboxylic acid component are subjected to a polycondensation reaction 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.

[0047] In this case, an esterification catalyst can be used as needed. Examples of esterification catalysts include tin-containing catalysts (e.g., dibutyltin oxide), antimony trioxide, titanium-containing catalysts (e.g., titanium alkoxides (tetrabutoxytitanate), potassium oxalate titanate, titanium terephthalate, titanium terephthalate alkoxides, catalysts described in JP 2006-243715 A (titanium diisopropoxybis(triethanolaminate), titanium dihydroxybis(triethanolaminate), titanium monohydroxytris(triethanolaminate), titanyl bis(triethanolaminate) and their intramolecular polycondensates, etc.), and catalysts described in JP 2007-11307 A (titanium tributoxyterephthalate, titanium triisopropoxyterephthalate, titanium diisopropoxyditerephthalate, etc.), zirconium-containing catalysts (e.g., zirconyl acetate), and zinc acetate. Among these, titanium-containing catalysts are preferred.

[0048] A stabilizer may be added to the polyester to ensure stable polymerization. Examples of the stabilizer include hydroquinone, methylhydroquinone, and hindered phenol compounds.

[0049] The polyester resin (B) is a polyester resin obtained by polycondensation of an alcohol component and a carboxylic acid component.

[0050] Examples of the alcohol component include the same alcohol components as those exemplified for the polyester resin (A), and the preferred alcohol components are also the same.

[0051] Examples of the carboxylic acid component include the same compounds as those exemplified as the carboxylic acid component of the polyester resin (A), and the preferred compounds are also the same.

[0052] The acid value of the polyester resin (B) is preferably 0 to 50 mgKOH / g, more preferably 0.1 to 30 mgKOH / g, from the viewpoints of low-temperature fixability, charge retention rate, and durability of print quality. The hydroxyl value of the polyester resin (B) is preferably from 0 to 50 mgKOH / g, more preferably from 0.1 to 30 mgKOH / g, from the viewpoints of low-temperature fixability, charge retention rate, and durability of print quality. The acid value and hydroxyl value can be measured by the method specified in JIS K0070.

[0053] The glass transition temperature of the polyester resin (B) is preferably from 50 to 75°C, more preferably from 55 to 70°C, from the viewpoint of heat-resistant storage stability and low-temperature fixability.

[0054] The peak top molecular weight of the polyester resin (B) is preferably from 2,000 to 100,000, more preferably from 4,000 to 20,000, from the viewpoint of hot offset resistance.

[0055] The flow softening point of the polyester resin (B) is 126 to 160°C, preferably 129 to 157°C, more preferably 132 to 154°C, and particularly preferably 135 to 151°C. If the flow softening point [T1 / 2] of (B) exceeds 160°C, there is a problem that the miscibility with the polyester resin (A) decreases. On the other hand, if the flow softening point [T1 / 2] of (B) is less than 126°C, there is a problem that it becomes difficult to achieve both low-temperature fixability and hot offset resistance. The method for measuring the flow softening point of the polyester resin (B) is the same as that for the polyester resin (A), and the method for adjusting the flow softening point is also the same as that for the polyester resin (A).

[0056] The solubility parameter of polyester resin (B), SP(B), is 10.6 to 12.4 (cal / cm) from the viewpoint of low-temperature fixability and heat-resistant storage stability. 3 ) 0.5 It is preferable that: The calculation method is the same as for SP(A).

[0057] From the viewpoints of storage stability and hydrolysis resistance under high temperature and humidity conditions, the xylene-insoluble content of the polyester resin (B) is preferably 10 to 50% by weight, more preferably 13 to 47% by weight, and even more preferably 15 to 45% by weight. The method for measuring the xylene-insoluble content of the polyester resin (B) is the same as the method for measuring the xylene-insoluble content of the polyester resin (A).

[0058] The polyester resin (B) in the present invention preferably contains 0 to 40 mol %, and more preferably 0 to 35 mol %, of ethylene glycol based on the total molar number of the constituting alcohol components, from the viewpoint of low temperature fixability. The polyester resin (B) in the present invention preferably contains 60 to 100 mol %, more preferably 65 to 100 mol %, of alcohol components other than ethylene glycol based on the total molar number of the constituent alcohol components, from the viewpoint of low-temperature fixability. The polyester resin (B) in the present invention preferably contains 40 to 75 mol %, and more preferably 45 to 70 mol %, of terephthalic acid based on the total number of moles of the carboxylic acid components constituting it, from the viewpoints of low-temperature fixability and hot offset resistance. The polyester resin (B) in the present invention preferably contains 25 to 60 mol %, and more preferably 30 to 55 mol %, of a carboxylic acid component other than terephthalic acid based on the total number of moles of the carboxylic acid components constituting the polyester resin (B) from the viewpoints of low-temperature fixability and hot offset resistance.

[0059] The reaction ratio of the alcohol component to the carboxylic acid component, expressed as the molar ratio of hydroxyl groups to carboxyl groups {[OH] / [COOH]}, 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, from the viewpoint of humidity and heat resistance storage stability.

[0060] The method for producing the polyester resin (B) is the same as the method for producing the polyester resin (A).

[0061] The weight ratio (A / B) of the polyester resin (A) and the polyester resin (B) is preferably 20 / 80 to 80 / 20, more preferably 30 / 70 to 70 / 30, from the viewpoints of low-temperature fixability and hot offset resistance.

[0062] The binder for the image-forming material in the present invention may contain, in addition to the polyester resin (A) and the polyester resin (B), resins such as vinyl resin, epoxy resin, polyurethane resin, polycarbonate resin, crystalline polyester resin, and crystalline vinyl resin.

[0063] The binder for image-forming materials of the present invention has a moisture content of 2000 to 9000 ppm after a 24-hour moisture absorption test at a temperature of 50° C. and a relative humidity of 80%, and preferably 3000 to 9000 ppm from the viewpoints of humidity and heat resistance storage stability and low-temperature fixability. If the moisture content of the binder for image-forming materials after a 24-hour moisture absorption test is less than 2000 ppm, the low-temperature fixability and colorant dispersibility are insufficient, and if it exceeds 9000 ppm, the humidity and heat resistance storage stability deteriorates. The moisture content after the 24-hour moisture absorption test can be adjusted, for example, by controlling the acid value, hydroxyl value, ester group concentration, and SP value of the polyester resin (A) and polyester resin (B). For example, increasing the acid value of the resin increases the moisture content after the 24-hour moisture absorption test. Increasing the hydroxyl value and ester group concentration of the resin increases the moisture content after the 24-hour moisture absorption test. Increasing the SP value of the resin increases the moisture content after the 24-hour moisture absorption test.

[0064] The moisture absorption test method for binders for image-forming materials at a temperature of 50° C. and a relative humidity of 80% for 24 hours will be described. 4 g of binder for image-forming materials, sieved to 150 to 355 μm mesh, is weighed into a plastic bottle and placed in a thermo-hygrostat (50°C, 80% relative humidity). 24 hours after placement, the bottle is removed from the thermo-hygrostat and the moisture content of the binder for image-forming materials is measured using a Karl Fischer moisture meter. Toluene / methanol = 70 / 30 (weight ratio) is used as the solvent for Karl Fischer measurement.

[0065] When the binder for an image-forming material of the present invention contains a resin other than the polyester resin (A) and the polyester resin (B), the total weight of the polyester resin (A) and the polyester resin (B) is preferably 50% by weight or more, more preferably 80% by weight or more, and particularly preferably 90% by weight or more, based on the total weight of the binder for an image-forming material, from the viewpoint of the fixing width of the toner. Furthermore, the weight proportion of resins other than the polyester resin (A) and the polyester resin (B) is preferably 50% by weight or less, more preferably 20% by weight or less, and particularly preferably 10% by weight or less, based on the total weight of the binder for the image-forming material, from the viewpoint of the fixing width of the toner.

[0066] The image-forming material of the present invention may contain, in addition to the binder for image-forming materials, one or more known additives selected from colorants, release agents, charge control agents, fluidizing agents, and the like, if necessary.

[0067] As the colorant, any dye or pigment used as a toner colorant can be used. Examples include carbon black, iron black, Sudan Black SM, Fast Yellow G, Benzidine Yellow, Pigment Yellow, India First 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. The colorant may be any one of these alone or a mixture of two or more. If necessary, magnetic powder (powder of ferromagnetic metals such as iron, cobalt, or nickel, or compounds such as magnetite, hematite, or ferrite) can be added to function as a colorant.

[0068] Examples of the release agent include aliphatic hydrocarbon waxes such as low molecular weight polypropylene, low molecular weight polyethylene, low molecular weight polypropylene / polyethylene copolymer, 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.

[0069] Examples of polyolefin waxes include (co)polymers of olefins (such as 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 olefin (co)polymers [for example, modified products of 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 to C18) esters and alkyl maleates (C1 to C18) esters, etc.], and Sasol wax.

[0070] The higher alcohols include aliphatic alcohols having 30 to 50 carbon atoms, such as triacontanol, and the fatty acids include aliphatic alcohols having 30 to 50 carbon atoms, such as triacontanol.

[0071] 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 salicylate salts, boron complexes of benzilic acid, sulfonic acid group-containing polymers, fluorine-containing polymers, and halogen-substituted aromatic ring-containing polymers. Specific examples of charge control agents include T-77 (azo-iron complex manufactured by Hodogaya Chemical Co., Ltd.).

[0072] Examples of the fluidizing agent include colloidal silica, alumina powder, and titanium oxide powder.

[0073] The content of the binder for the image-forming material is preferably 30 to 95% by weight, more preferably 40 to 90% by weight, and even more preferably 50 to 86% by weight, based on the weight of the image-forming material.

[0074] The content of the colorant is preferably 0.05 to 60% by weight, more preferably 0.1 to 55% by weight, and even more preferably 0.5 to 50% by weight, based on the weight of the binder for the image-forming material. The content of the release agent is preferably 0 to 30% by weight, more preferably 0.5 to 20% by weight, and even more preferably 1 to 10% by weight, based on the weight of the binder for the image-forming material. The content of the charge control agent is preferably 0 to 20% by weight, more preferably 0.1 to 10% by weight, and even more preferably 0.5 to 7.5% by weight, based on the weight of the binder for the image-forming material. The content of the fluidizing agent is preferably 0 to 10% by weight, more preferably 0 to 5% by weight, and even more preferably 0.1 to 4% by weight, based on the weight of the binder for the image-forming material. The total content of the additives is preferably 3 to 70% by weight, more preferably 4 to 58% by weight, and even more preferably 5 to 50% by weight, based on the weight of the binder for the image-forming material. By setting the composition ratio of the image-forming material within the above range, it is possible to easily obtain an image-forming material that has good low-temperature fixing properties, hot offset resistance, chargeability (charge retention rate), durability of print quality, and durability of the image-forming material.

[0075] The image-forming material may be obtained by any of known methods such as kneading and pulverization, emulsion phase inversion, and polymerization. For example, when an image-forming material is obtained by a kneading and pulverizing method, the components constituting the image-forming material, excluding the fluidizing agent, are dry-blended, melt-kneaded, then coarsely pulverized, and finally 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 image-forming material. The volume average particle size (D50) is measured using a Coulter counter (for example, Multisizer III (trade name, manufactured by Beckman Coulter, Inc.)).

[0076] When the image-forming material is obtained by the emulsion phase inversion method, the components constituting the image-forming material except for the fluidizing agent are dissolved or dispersed in an organic solvent, and then emulsified by adding water, etc., and if necessary, the resulting mixture is subjected to aggregation, etc., followed by separation and classification, whereby the image-forming material can be produced. The volume average particle size of the image-forming material is preferably 3 to 15 μm.

[0077] In the case of toner applications, 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 needed to be used as a developer for electric latent images. When carrier particles are used, the weight ratio of toner to carrier particles is preferably 1 / 99 to 99 / 1. Alternatively, an electric latent image can be formed by friction with a member such as a charging blade instead of carrier particles. The toner does not necessarily contain carrier particles.

[0078] The image-forming material is fixed to a support (paper, polyester film, etc.) by a copier, printer, etc. to form a recording material. As a method for fixing to a support, known methods such as a heat roll fixing method and a flash fixing method can be used.

[0079] The image-forming material 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 particularly suitable for full color applications.

[0080] The present specification discloses the following:

[0081] The present disclosure (1) is a binder for an image-forming material, which comprises a polyester resin (A) and a polyester resin (B) obtained by polycondensation of an alcohol component and a carboxylic acid component, wherein the polyester resin (A) contains 28 to 88 mol % of ethylene glycol based on the total number of moles of the alcohol components, and 55 to 99 mol % of terephthalic acid based on the total number of moles of the carboxylic acid components, the polyester resin (A) has a flow softening point of 90°C to 125°C, and the polyester resin (B) has a flow softening point of 126°C to 160°C, and the moisture content after a 24-hour moisture absorption test at a temperature of 50°C and a relative humidity of 80% is 2000 to 9000 ppm. The present disclosure (2) is the binder for an image-forming material according to the present disclosure (1), wherein the difference obtained by subtracting the xylene-insoluble content of the polyester resin (A) from the xylene-insoluble content of the polyester resin (B) is 5 to 50 percentage points. The present disclosure (3) is the binder for an image-forming material according to the present disclosure (1) or (2), wherein the polyester resin (A) contains calcium in the range of 10 to 4000 ppm as measured by fluorescent X-rays. [Example]

[0082] The present invention will be further explained below with reference to examples and comparative examples, but the present invention is not limited to these.

[0083] <Production Example 1> Synthesis of polyester resin (A1) A pressurizable reactor was charged with 331.3 parts by weight (174.1 mol%) of ethylene glycol and 561.1 parts by weight of recycled PET resin (equivalent to 85.6 mol% ethylene glycol and 97.2 mol% terephthalic acid). The depolymerization reaction (closed-circuit transesterification) was carried out at 220 °C for 2 hours with stirring. The depolymerized product was then cooled to 180 °C. 482.5 parts by weight (45.2 mol%) of bisphenol A·PO 2-mol adduct and 2.0 parts by weight of titanium diisopropoxybis(triethanolamine) were added. The reaction mixture was heated to 220 °C and depressurized under a pressure of 0.5 to 2.5 kPa to remove 389.9 parts by weight (204.9 mol%) of ethylene glycol. The peak-top molecular weight reached 5,000, and the mixture was then cooled to 175 °C. Next, 14.5 parts by weight (2.8 mol%) of trimellitic anhydride was added, and esterification was carried out at 175° C. for 1 hour under normal pressure, followed by removal from the flask to obtain a polyester resin (A1). The mole percentages of the alcohol component and the carboxylic acid component are ratios calculated based on the total number of moles of each component constituting the polyester resin, and the same applies to the following production examples.

[0084] <Production Example 2> Synthesis of polyester resin (A2) In a pressurizable reactor, 308.2 parts by weight of recovered PET resin (equivalent to 60.5 mol% ethylene glycol, 71.4 mol% terephthalic acid), 591.0 parts by weight (71.3 mol%) of bisphenol A·PO 2 molar adduct, 145.5 parts by weight (26.5 mol%) of dodecenyl succinic anhydride, and 2.0 parts by weight of titanium diisopropoxybis(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 46.8 parts by weight (31.8 mol%) of ethylene glycol. When the peak top molecular weight reached 6,300, the mixture was cooled to 175 °C. Next, 9.4 parts by weight (2.1 mol%) of trimellitic anhydride was added, and esterification was carried out at 175 °C for 1 hour at normal pressure, followed by removal of the mixture to obtain polyester resin (A2).

[0085] <Production Example 3> Synthesis of polyester resin (A3) A pressurizable reactor was charged with 91 parts by weight (47.6 mol%) of ethylene glycol and 520 parts by weight of recycled PET resin (equivalent to 79.0 mol% ethylene glycol and 89.2 mol% terephthalic acid). The depolymerization reaction (closed-circuit transesterification) was carried out at 220 °C for 2 hours with stirring. The depolymerized product was then cooled to 180 °C and charged with 444 parts by weight (41.4 mol%) of bisphenol A·PO 2-mol adduct, 67 parts by weight (9.0 mol%) of dodecenylsuccinic anhydride, and 2.0 parts by weight of titanium diisopropoxybis(triethanolamine) as a condensation catalyst. The reaction mixture was heated to 220 °C and depressurized at 0.5 to 2.5 kPa to remove 130 parts by weight (68.0 mol%) of ethylene glycol. The peak-top molecular weight reached 6,400, and the mixture was then cooled to 175 °C. Next, 9 parts by weight (1.8 mol%) of trimellitic anhydride was added, and esterification was carried out at 175°C for 1 hour under normal pressure, followed by removal from the flask to obtain a polyester resin (A3).

[0086] <Production Example 4> Synthesis of polyester resin (A4) A pressurizable reaction vessel was charged with 343.9 parts by weight (115.3 mol%) of ethylene glycol, 79.8 parts by weight (16.0 mol%) of 1,5-neopentyl glycol, and 582.5 parts by weight of recovered PET resin (corresponding to 56.7 mol% of ethylene glycol and 59.0 mol% of terephthalic acid), and a 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, 306.9 parts by weight (39.3 mol%) of isophthalic acid and 2.0 parts by weight of titanium diisopropoxybis(triethanolamine) as a condensation catalyst were added, and the temperature was raised to 220 ° C. while removing 176.5 parts by weight (88.0 mol%) of ethylene glycol and condensed water under a reduced pressure of 0.5 to 2.5 kPa. The acid value was 1 mg KOH / g, and the Mw was 10500. When the mixture was cooled to 175 ° C., 15.4 parts by weight (1.7 mol%) of trimellitic anhydride was added, and esterification was carried out at normal pressure for 1 hour at 175 ° C., followed by removal to obtain polyester resin (A4).

[0087] Comparative Production Example 1 Synthesis of Polyester Resin (A'1) A pressurizable reactor was charged with 492.5 parts by weight (183.1 mol%) of ethylene glycol and 834.0 parts by weight of recycled PET resin (equivalent to 90.1 mol% ethylene glycol and 95.7 mol% terephthalic acid). The depolymerization (closed-cell transesterification) was carried out at 220 °C for 2 hours with stirring. The depolymerized product was then cooled to 180 °C. 127.3 parts by weight (8.4 mol%) of bisphenol A·PO 2-mol adduct and 2.0 parts by weight of titanium diisopropoxybis(triethanolamine) were added. The temperature was raised to 220 °C while the pressure was reduced from 0.5 to 2.5 kPa to remove 488.5 parts by weight (181.7 mol%) of ethylene glycol. The peak-top molecular weight reached 5,400, and the reactor was then cooled to 175 °C. Next, 34.2 parts by weight (4.3 mol%) of trimellitic anhydride was added, and esterification was carried out at 175° C. for 1 hour under normal pressure, followed by removal from the flask to obtain a polyester resin (A′1).

[0088] Comparative Production Example 2: Synthesis of polyester resin (A'2) A pressurizable reactor was charged with 254.6 parts by weight (166.5 mol%) of ethylene glycol and 431.1 parts by weight of recycled PET resin (equivalent to 81.9 mol% ethylene glycol and 100 mol% terephthalic acid). The depolymerization reaction (closed-cell transesterification) was carried out at 220 °C for 2 hours with stirring. The depolymerized product was then cooled to 180 °C. 658.0 parts by weight (76.7 mol%) of bisphenol A·PO 2 mol adduct and 2.0 parts by weight of titanium diisopropoxybis(triethanolamine) were added. The temperature was raised to 220 °C while the pressure was reduced from 0.5 to 2.5 kPa to remove 344.2 parts by weight (225.2 mol%) of ethylene glycol. The peak-top molecular weight reached 5700. The mixture was then cooled to 175 °C and discharged to obtain polyester resin (A'2).

[0089] Comparative Production Example 3: Synthesis of polyester resin (A'3) A pressurizable reaction vessel was charged with 316.6 parts by weight (105.6 mol%) of ethylene glycol, 80.2 parts by weight (15.9 mol%) of 1,5-neopentyl glycol, and 536.2 parts by weight of recovered PET resin (corresponding to 52.0 mol% of ethylene glycol and 54.1 mol% of terephthalic acid), and a 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, 346.8 parts by weight (44.2 mol%) of isophthalic acid and 2.0 parts by weight of titanium diisopropoxybis(triethanolamine) as a condensation catalyst were added, and the mixture was heated to 220 ° C. while removing 220.5 parts by weight (73.6 mol%) of ethylene glycol and condensed water under a reduced pressure of 0.5 to 2.5 kPa. When the acid value reached less than 1 and Mw reached 10,000, the mixture was cooled to 175 ° C. Next, 15.4 parts by weight (1.7 mol%) of trimellitic anhydride was added, and esterification was carried out at normal pressure for 1 hour at 175 ° C., followed by removal to obtain polyester resin (A'3).

[0090] Comparative Production Example 4: Synthesis of polyester resin (A'4) A pressurizable reactor was charged with 307.0 parts by weight of recovered PET resin (equivalent to 57.3 mol% ethylene glycol, 72.0 mol% terephthalic acid), 588.7 parts by weight (67.4 mol%) of bisphenol A·PO 2 molar adduct, 144.9 parts by weight (26.7 mol%) of dodecenyl succinic anhydride, and 2.0 parts by weight of titanium diisopropoxybis(triethanolamine) as a condensation catalyst. The temperature was raised to 220 °C while the pressure was reduced to 0.5-2.5 kPa to remove 38.5 parts by weight (24.7 mol%) of ethylene glycol. When the peak top molecular weight reached 4200, the reactor was cooled to 175 °C. Next, 5.1 parts by weight (1.3 mol%) of trimellitic anhydride was added, and the mixture was esterified at 175 °C for 1 hour at normal pressure, after which the polyester resin (A'4) was obtained.

[0091] The physical properties of polyester resins (A1) to (A4) and polyester resins (A'1) to (A'4) are shown in Table 1. In the table, "(equivalent amount in PET resin)" means the number of moles of the constituent component contained in polyethylene terephthalate.

[0092] [Table 1]

[0093] <Production Example 5> Synthesis of polyester resin (B1) A reactor was charged with 197.8 parts by weight (29.2 mol%) of bisphenol A·PO 2-mol adduct, 535.9 parts by weight (70.8 mol%) of bisphenol A·PO 3-mol adduct, 172.4 parts by weight (53.6 mol%) of terephthalic acid, 66.9 parts by weight (23.6 mol%) of adipic acid, 5.9 parts by weight (1.6 mol%) of trimellitic anhydride, and 1 part by weight of tetrabutoxy titanate as a condensation catalyst. The mixture was reacted at 220°C under a nitrogen stream for 4 hours while distilling off the water produced, followed by 2 hours under a reduced pressure of 0.5 to 2.5 kPa. Subsequently, 78.9 parts by weight (21.2 mol%) of trimellitic anhydride was added at 210°C, and the mixture was reacted for 1 hour under normal pressure, followed by 10 hours under a reduced pressure of 0.5 to 5 kPa. The resulting resin was cooled to room temperature, crushed, and granulated to obtain polyester resin (B1).

[0094] <Production Example 6> Synthesis of polyester resin (B2) A reactor was charged with 122.5 parts by weight (17.1 mol%) of bisphenol A·PO 2-mol adduct, 460.0 parts by weight (57.4 mol%) of bisphenol A·PO 3-mol adduct, 169.7 parts by weight (25.5 mol%) of bisphenol A·EO 2-mol adduct, 187.3 parts by weight (67.0 mol%) of terephthalic acid, 53.8 parts by weight (16.6 mol%) of trimellitic anhydride, and 1 part by weight of tetrabutoxy titanate as a condensation catalyst. The mixture was reacted at 220°C under a nitrogen stream for 4 hours while distilling off the water produced, followed by 2 hours under a reduced pressure of 0.5 to 2.5 kPa. Subsequently, 53.2 parts by weight (16.4 mol%) of trimellitic anhydride was added at 210°C, and the mixture was reacted for 1 hour under normal pressure, followed by 10 hours under a reduced pressure of 0.5 to 5 kPa. The resulting resin was cooled to room temperature, crushed, and granulated to obtain polyester resin (B2).

[0095] <Production Example 7> Synthesis of polyester resin (B3) A reactor was charged with 366.4 parts by weight (30.0 mol%) of bisphenol A·PO 2-mol adduct, 251.6 parts by weight (115.0 mol%) of ethylene glycol, 294.3 parts by weight (47.9 mol%) of terephthalic acid, 126.1 parts by weight (20.5 mol%) of isophthalic acid, 77.1 parts by weight (17.1 mol%) of benzoic acid, 36.1 parts by weight (5.1 mol%) of trimellitic anhydride, and 1 part by weight of tetrabutoxy titanate as a condensation catalyst. The mixture was reacted at 220°C under a nitrogen stream for 4 hours while distilling off the resulting water and 98.9 parts by weight (45.0 mol%) of ethylene glycol. The mixture was then reacted for 2 hours under a reduced pressure of 0.5 to 2.5 kPa. 66.7 parts by weight (9.4 mol%) of trimellitic anhydride was then added at 210°C. The mixture was reacted for 1 hour under normal pressure, followed by 10 hours under a reduced pressure of 0.5 to 5 kPa, and then discharged. The resulting resin was cooled to room temperature, and then crushed and granulated to obtain a polyester resin (B3).

[0096] <Production Example 8> Synthesis of polyester resin (B4) A reactor was charged with 770.9 parts by weight (100.0 mol%) of bisphenol A·EO 2-mol adduct, 204.4 parts by weight (74.9 mol%) of terephthalic acid, 79.5 parts by weight (25.1 mol%) of trimellitic anhydride, and 2.5 parts by weight of titanium diisopropoxybis(triethanolamine) as a condensation catalyst. The mixture was reacted at 220°C under a nitrogen stream for 4 hours while distilling off the water produced, and then reacted under a reduced pressure of 0.5 to 5 kPa for 10 hours, after which the mixture was discharged. The resulting resin was cooled to room temperature, pulverized, and granulated to obtain polyester resin (B4).

[0097] <Production Example 9> Synthesis of polyester resin (B5) A reactor was charged with 769.3 parts by weight (100.0 mol%) of bisphenol A·EO 2-mol adduct, 205.8 parts by weight (74.9 mol%) of terephthalic acid, 80.0 parts by weight (25.1 mol%) of trimellitic anhydride, and 2.5 parts by weight of titanium diisopropoxybis(triethanolamine) as a condensation catalyst. The mixture was reacted at 220°C under a nitrogen stream for 4 hours while distilling off the water produced, and then reacted for 10 hours under a reduced pressure of 0.5 to 5 kPa. The resulting resin was then cooled to room temperature and crushed to obtain polyester resin (B5).

[0098] <Production Example 10> Synthesis of polyester resin (B6) A reaction vessel was charged with 267.1 parts by weight (37.2 mol%) of bisphenol A·PO 2-mol adduct, 301.5 parts by weight (37.5 mol%) of bisphenol A·PO 3-mol adduct, 170.5 parts by weight (25.3 mol%) of bisphenol A·EO 2-mol adduct, 188.6 parts by weight (63.9 mol%) of terephthalic acid, 54.2 parts by weight (15.9 mol%) of trimellitic anhydride, and 2.5 parts by weight of titanium diisopropoxybis(triethanolamine) as a condensation catalyst. The mixture was reacted at 220°C under a nitrogen stream for 4 hours while distilling off the water produced, and then further reacted for 2 hours under a reduced pressure of 0.5 to 5 kPa. The acid value was confirmed to be less than 1. Next, 68.8 parts by weight (20.2 mol%) of trimellitic anhydride was added at the same temperature, and the mixture was allowed to react under normal pressure for 1 hour, followed by esterification under reduced pressure at 75 kPa. After confirming a flow softening point of 138°C, the mixture was removed from the reaction vessel into a metal container, and the esterification reaction was allowed to proceed while the removed material was cooled in the metal container. After the resin was cooled to room temperature, it was pulverized and granulated to obtain polyester resin (B6).

[0099] Comparative Production Example 5 Synthesis of Polyester Resin (B'1) A reactor was charged with 45.5 parts by weight (6.0 mol%) of bisphenol A·PO 2-mol adduct, 373.3 parts by weight (44.0 mol%) of bisphenol A·PO 3-mol adduct, 356.1 parts by weight (50.0 mol%) of bisphenol A·EO 2-mol adduct, 189.4 parts by weight (71.8 mol%) of terephthalic acid, and 2.5 parts by weight of titanium diisopropoxybis(triethanolamine) as a condensation catalyst. The mixture was reacted at 220°C under a nitrogen stream for 4 hours while distilling off the water produced. The acid value was confirmed to be less than 1. The mixture was then cooled to 190°C, and 87.1 parts by weight (28.2 mol%) of trimellitic anhydride was added. The mixture was reacted at the same temperature and atmospheric pressure for 1 hour. The pressure was then reduced to 0.5-2.5 kPa. The flow softening point was confirmed to be 122°C before the mixture was discharged. The resulting resin was cooled to room temperature, pulverized, and granulated to obtain polyester resin (B'1).

[0100] Comparative Production Example 6: Synthesis of polyester resin (B'2) A reaction vessel was charged with 368.1 parts by weight (29.8 mol%) of bisphenol A·PO 2-mol adduct, 252.8 parts by weight (114.9 mol%) of ethylene glycol, 295.7 parts by weight (47.9 mol%) of terephthalic acid, 126.7 parts by weight (20.5 mol%) of isophthalic acid, 77.5 parts by weight (17.1 mol%) of benzoic acid, 36.3 parts by weight (5.1 mol%) of trimellitic anhydride, and 1 part by weight of tetrabutoxy titanate as a condensation catalyst. The mixture was reacted at 220°C under a nitrogen stream for 4 hours while distilling off the resulting water and 104.3 parts by weight (44.7 mol%) of ethylene glycol, and then reacted for 2 hours under a reduced pressure of 0.5 to 2.5 kPa. Then, 67.0 parts by weight (9.4 mol%) of trimellitic anhydride was added at 210°C, and the mixture was reacted under normal pressure for 1 hour, then under reduced pressure of 0.5 to 5 kPa for 10 hours, and then discharged. The resulting resin was cooled to room temperature, pulverized, and granulated to obtain polyester resin (B'2).

[0101] Table 2 shows the physical properties of the polyester resins (B1) to (B6) and the polyester resins (B′1) to (B′2).

[0102] [Table 2]

[0103] <Examples 1 to 8> Using a Henschel mixer [FM10B manufactured by Mitsui Miike Chemical Engineering Co., Ltd.], polyester resin (A) and polyester resin (B) were mixed according to the compounding ratio (parts by weight) in Table 3 to obtain binders for image-forming materials (C1) to (C8). Next, each of the binders for image-forming materials (C1) to (C8) was premixed with a colorant, a release agent, and a charge control agent, and then kneaded in a twin-screw kneader (PCM-30, manufactured by Ikegai Corporation). The mixture was then finely pulverized using a supersonic jet mill, Labojet (manufactured by Nippon Pneumatic Mfg. Co., Ltd.), and then classified using an air classifier (MDS-I, manufactured by Nippon Pneumatic Mfg. Co., Ltd.) to obtain toner particles with a particle size D50 of 7 μm. Next, 100 parts by weight of the toner particles were mixed with 0.5 parts by weight of colloidal silica (Aerosil R972, manufactured by Nippon Aerosil Co., Ltd.) using a sample mill to obtain toners (T1) to (T8), which are image-forming materials.

[0104] <Comparative Examples 1 to 6> Using a Henschel mixer [FM10B manufactured by Mitsui Miike Chemical Engineering Co., Ltd.], polyester resin (A) or (A') and polyester resin (B) or (B') were mixed according to the compounding ratio (parts by weight) in Table 3 to obtain binders (C'1) to (C'6) for image-forming materials, respectively. Next, each of the binders for image-forming materials (C'1) to (C'6) was premixed with a colorant, a release agent, and a charge control agent, and then kneaded in a twin-screw kneader (PCM-30, manufactured by Ikegai Corporation). The mixture was then finely pulverized using a supersonic jet mill, Labojet (manufactured by Nippon Pneumatic Mfg. Co., Ltd.), and then classified using an air classifier (MDS-I, manufactured by Nippon Pneumatic Mfg. Co., Ltd.) to obtain toner particles with a particle size D50 of 7 μm. Next, 100 parts by weight of the toner particles were mixed with 0.5 parts by weight of colloidal silica (Aerosil R972, manufactured by Nippon Aerosil Co., Ltd.) using a sample mill to obtain toners (T'1) to (T'8), which are image-forming materials.

[0105] The results of evaluating the moisture content of binders for image-forming materials (C1) to (C8) and binders for image-forming materials (C'1) to (C'6) after a 24-hour moisture absorption test at a temperature of 50°C and a relative humidity of 80%, as well as the xylene-insoluble content of polyester resin (B) and the xylene-insoluble content of polyester resin (A) measured by the above-mentioned method and the difference calculated are shown in Table 3. Furthermore, the results of evaluating toners (T1) to (T8) and toners (T'1) to (T'6) by the following method are shown in Table 4. The colorants, release agents, and charge control agents in Table 4 are as follows: Colorant: Carbon black MA-100 [Mitsubishi Chemical Corporation] Release agent: Carnauba wax [Toyo Adle Co., Ltd.] Charge control agent: T-77 [Hodogaya Chemical]

[0106] [Evaluation method] <Moisture content> The moisture content of the binder for image-forming materials after a 24-hour moisture absorption test at a temperature of 50°C and a relative humidity of 80% was measured by weighing 4 g of the binder for image-forming materials, which had been crushed in a mill and then sieved to a mesh size of 150 to 355 μm, into a plastic bottle and placing it in a thermo-hygrostat (50°C, 80% relative humidity). After 24 hours, the bottle was removed from the thermo-hygrostat and the moisture content in the binder for image-forming materials was measured using a Karl Fischer moisture meter. Toluene / methanol = 70 / 30 (weight ratio) was used as the solvent for the Karl Fischer measurement.

[0107] <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 with the heat fixing unit removed. This paper was passed through a soft roller at a fixing speed (peripheral speed of the heating roller) of 213 mm / sec, and at a 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 observed, and the temperature at which cold offset occurred (MFT) was measured. The lower the temperature at which cold offset occurs, the better the low-temperature fixability. Under these evaluation conditions, it is generally preferable that the MFT is 125° C. or less.

[0108] <Hot offset resistance (hot offset occurrence temperature)> Using the same method as described above for low-temperature fixability, the toner was placed on the paper surface, 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 a heating roller temperature 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 hot offset occurred was measured. The higher the temperature at which hot offset occurs, the better the hot offset resistance. Under these evaluation conditions, a temperature of 180° C. or higher is preferred.

[0109] <Heat and humidity resistance> 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 an airtight container, and left to stand for 24 hours in an atmosphere of 45°C and 90% relative humidity. The cohesion was measured using a powder tester, and the heat-resistant storage stability was evaluated. The lower the value in the cohesion test determined by the following method, the better the heat-resistant storage stability. Under these evaluation conditions, a value of 5% or less is preferred. Equipment: Powder Tester model PT-X (manufactured by Hosokawa Micron) Sieve openings: 355μm, 250μm, 150μm Vibration width: 1mm Vibration duration: 30 seconds Operation method: Place 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 at a vibration amplitude of 1mm for 30 seconds, then measure the weight of toner remaining on each sieve. Cohesion: Calculated from the weight of the toner used for measurement and the weight of the toner remaining after sieving. Cohesion degree (%)=(U / N+M / N×3 / 5+L / N×1 / 5)×100 U: Weight of the top row, M: Weight of the middle row, L: Weight of the bottom row, N: Weight of the sample (1g)

[0110] <Colorant dispersibility> The toners obtained in the examples and comparative examples were sliced ​​to approximately 100 μm in thickness, and the colorants dispersed in the toner were stained with ruthenium tetroxide at a concentration of 1 for 3 minutes using a vacuum electron staining device (VSC1R1H manufactured by Filgen Co., Ltd.). The dispersion state of the colorants, which appeared gray or black due to the ruthenium tetroxide staining, was then observed at a magnification of 10,000 times using a transmission electron microscope (TEM) on the cross section. The dispersion state of the colorants was confirmed based on the results of the toner cross section observation, and a three-level ranking was performed. A ranking of 3 or higher was desirable. Rating 4: The rate of colorant coalescence seen per field of view is 4% or less Grade 3: Coalescence of pigments is observed at a rate of 5-9% per visual field. Grade 2: Coalescence of colorants is observed in 10-29% of the visual field. Rating 1: Coalescence of colorants is observed in 30% or more of the visual field.

[0111] [Table 3]

[0112] [Table 4] [Industrial Applicability]

[0113] The image-forming material of the present invention is excellent in low-temperature fixability, hot offset resistance, and moist heat storage resistance, and therefore can be suitably used as a toner for developing electrostatic images used in electrophotography, electrostatic recording, electrostatic printing, etc. Furthermore, it can be suitably used as a surface modifier for inkjet recording media.

Claims

1. The binder for an image-forming material contains a polyester resin (A) and a polyester resin (B) obtained by polycondensing an alcohol component and a carboxylic acid component, wherein the polyester resin (A) contains 28 to 88 mol % of ethylene glycol based on the total number of moles of the alcohol components, and 55 to 99 mol % of terephthalic acid based on the total number of moles of the carboxylic acid components, the polyester resin (A) has a flow softening point of 90°C to 125°C, and the polyester resin (B) has a flow softening point of 126°C to 160°C, and the binder for an image-forming material has a moisture content of 2000 to 9000 ppm after a 24-hour moisture absorption test at a temperature of 50°C and a relative humidity of 80%.

2. 2. The binder for an image-forming material according to claim 1, wherein the difference obtained by subtracting the xylene-insoluble content of the polyester resin (A) from the xylene-insoluble content of the polyester resin (B) is 5 to 50 percentage points.

3. 3. The binder for an image-forming material according to claim 1, wherein the polyester resin (A) contains calcium in the range of 10 to 4000 ppm as measured by fluorescent X-rays.

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