Toner Wax

Abstract

To provide a wax for toner, capable of imparting storage stability at low temperature to toner, with excellent storage stability in toner, and allowing high image quality of a toner-printed matter to be achieved with improved coloring of toner.SOLUTION: A wax for toner comprises an ester compound satisfying the following conditions (A), (B) and (C). (A) Mole percentage A of a component derived from pentaerythritol is 19.0 to 25.0 mol%. (B) Mole percentage B of a component derived from a straight chain saturated fatty acid having 14 to 24 carbon atoms is 55.0 to 80.5 mol%. (C) Mole percentage C of a component derived from adipic acid is 0.50 to 20.0 mol%.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a wax for toner suitable for use in a toner for a recording method for developing an electrostatic image, such as an electrophotographic method or an electrostatic recording method, in an image forming apparatus such as a copying machine or a laser printer. [Background technology]

[0002] Toners used in image forming devices such as copiers and printers contain a thermoplastic resin that serves as a binder resin, a colorant (carbon black, magnetic powder, pigment, etc.), a charge control agent, and wax, and may further contain a fluidity additive, a cleaning aid, and a transfer aid, as necessary. Among these, wax prevents the toner from remaining on the fixing roll during fixing (filming), and promotes the softening of the thermoplastic resin to improve fixing ability. In recent years, with the rise in environmental awareness worldwide, emphasis has been placed on low-temperature fixing ability of toner to reduce power consumption, and wax has a low melting point, so there is a demand for it to improve the low-temperature fixing ability of toner by lowering the melting temperature of the thermoplastic resin.

[0003] On the other hand, wax can cause poor image quality because it can bleed excessively onto the surface of the molten toner and adhere to fixing members such as the fixing roller and fixing belt. In addition, bleeding of the wax during toner storage can cause blocking between toner particles. Therefore, studies are being conducted to improve the storage stability of toner by using high-molecular-weight synthetic multifunctional ester waxes that are less likely to bleed during toner storage. Furthermore, in recent years, with the spread of print-on-demand digital printing in the commercial printing field, printed materials with high graphic output and unprecedented metallic-toned printed materials have appeared, and as the demand for toners with good color development increases, materials that can contribute to high color development are required.

[0004] For example, Patent Document 1 discloses a toner using a polyfunctional polyester wax obtained from pentaerythritol, a fatty acid having 11 to 30 carbon atoms, and a fatty acid having 1 to 10 carbon atoms. It is described that these polyfunctional polyester waxes are excellent in low-temperature fixability and storage stability. However, when the wax of Patent Document 1 is used, the color development of the toner cannot be improved.

[0005] Furthermore, Patent Document 2 describes a method for producing an ester wax for toner, which comprises condensing a linear saturated monocarboxylic acid or a mixture thereof selected from those having 14 to 30 carbon atoms with a linear saturated monohydric alcohol or a mixture thereof selected from those having 14 to 30 carbon atoms, or a dihydric to hexahydric polyhydric alcohol or a mixture thereof selected from those having 2 to 30 carbon atoms, and then neutralizing the mixture with an aqueous alkali solution and removing the neutralized salt by centrifugation, and describes that the use of the wax provides a toner with excellent low-temperature fixing properties and storage stability. However, even when the wax of Patent Document 2 is used, the color development of the toner cannot be improved. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 7-98511 [Patent Document 2] JP 2012-32479 A Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a wax for a toner that can impart low-temperature fixing properties to a toner, exhibits excellent storage stability in the toner, and further improves the color development of the toner, thereby contributing to high image quality of toner prints. [Means for solving the problem]

[0008] The present inventors conducted extensive research to solve the above problems, and as a result, discovered that when an ester compound containing (A) a component derived from pentaerythritol, (B) a component derived from a linear saturated fatty acid having 14 to 24 carbon atoms, and (C) a component derived from adipic acid in specific ratios is used as a toner wax, it is possible to impart low-temperature fixing properties to the toner, and the toner exhibits excellent storage stability, and furthermore, the color development of the toner is improved, thereby contributing to high image quality of toner prints, and thus completed the present invention.

[0009] That is, the toner wax composition of the present invention is characterized by comprising (A) an ester compound having a molar percentage A mol% of a component derived from pentaerythritol of 19.0 to 25.0 mol%, (B) a molar percentage B mol% of a component derived from a linear saturated fatty acid having 14 to 24 carbon atoms of 55.0 to 80.5 mol%, and (C) a molar percentage C mol% of a component derived from adipic acid of 0.50 to 20.0 mol%. Effect of the Invention

[0010] The toner wax of the present invention is capable of imparting low-temperature fixing properties to the toner, exhibits excellent storage stability in the toner, and further has the effect of contributing to the improvement of image quality of toner prints by improving the color development of the toner. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described. In this specification, a numerical range defined using the symbol "~" is intended to include both the upper and lower limits of the range. For example, "2~5" means 2 or more and 5 or less.

[0012] The toner wax of the present invention is an ester compound containing (A) a component derived from pentaerythritol as an alcohol component, (B) a component derived from a linear saturated fatty acid having 14 to 24 carbon atoms as a first acid component, and (C) a component derived from adipic acid as a second acid component. When an ester compound containing (A) a component derived from pentaerythritol, (B) a component derived from a linear saturated fatty acid having 14 to 24 carbon atoms, and (C) a component derived from adipic acid in specific ratios is used as a toner wax, it is believed that compatibility with binder resins is appropriately improved and compatibility with colorants is also increased. Since the compatibility of the wax with the binder resin is appropriately improved, the softening temperature of the resin is lowered, which gives the toner low-temperature fixability, and the toner is less likely to bleed, which is believed to show excellent storage stability. In addition, since the compatibility of the wax with the colorant is also high, the colorant dispersion is not inhibited, and the color development of the toner is improved. Furthermore, the low-temperature fixability and storage stability, as well as the color development of the toner, are believed to contribute to the high image quality of toner prints.

[0013] As the raw material for the pentaerythritol-derived constituent component (A) which is the alcohol component, pentaerythritol or a pentaerythritol derivative which gives the same constituent unit as pentaerythritol in an ester synthesis reaction can be used. Pentaerythritol is a neopentyl polyol having a neopentyl skeleton, and therefore has excellent oxidation stability and heat resistance. Other neopentyl polyols include neopentyl glycol, trimethylolpropane, and dipentaerythritol. However, when neopentyl glycol or trimethylolpropane is used as the alcohol component, the melting point of the resulting ester is significantly lowered, and the storage stability in the toner may be deteriorated, and when dipentaerythritol is used as the alcohol component, the viscosity is significantly increased, and the low-temperature fixability may not be sufficiently imparted. For this reason, the neopentyl polyol used in the present invention is preferably pentaerythritol.

[0014] As the raw material for the first acid component (B) derived from a linear saturated fatty acid having 14 to 24 carbon atoms, a linear saturated fatty acid having 14 to 24 carbon atoms or a fatty acid derivative that gives the same structural unit as a linear saturated fatty acid having 14 to 24 carbon atoms in an ester synthesis reaction can be used. Examples of the linear saturated fatty acid having 14 to 24 carbon atoms used in the present invention include myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, and lignoceric acid. In the present invention, a mixed carboxylic acid containing two or more of these monovalent linear saturated carboxylic acids may be used. Among the linear saturated fatty acids, palmitic acid, stearic acid, arachidic acid, and behenic acid are preferred, and stearic acid, arachidic acid, and behenic acid are particularly preferred. If the number of carbon atoms is less than 14, the melting point may decrease and the storage stability in the toner may deteriorate, whereas if the number of carbon atoms is more than 24, the low-temperature fixability may be insufficient.

[0015] As the raw material for the second acid component (C) adipic acid-derived constituent, adipic acid, which is a divalent carboxylic acid, or an adipic acid derivative that gives the same constituent unit as adipic acid in an ester synthesis reaction can be used. When succinic acid having fewer carbon atoms than adipic acid is used as the divalent carboxylic acid, the heat resistance may be significantly deteriorated, and when sebacic acid having more carbon atoms than adipic acid is used, the melting point may be significantly lowered, and the storage stability in the toner may be deteriorated.

[0016] The toner wax of the present invention is composed of an ester compound having (A) a molar percentage Amol% of a component derived from pentaerythritol of 19.0 to 25.0mol%, (B) a molar percentage Bmol% of a component derived from a linear saturated fatty acid having 14 to 24 carbon atoms of 55.0 to 80.5mol%, and (C) a molar percentage Cmol% of a component derived from adipic acid of 0.50 to 20.0mol%. If the respective contents of components (A), (B) and (C) are out of the above ranges, the low-temperature fixing property and storage stability of the toner may become insufficient, and the effect of improving the color development of the toner may not be obtained. From this viewpoint, the molar percentage Amol% of the component derived from (A) pentaerythritol is preferably 20.0-24.0mol%, more preferably 20.5-22.5mol%. The molar percentage Bmol% of the component derived from (B) linear saturated fatty acid having 14-24 carbon atoms is preferably 57.5-78.5mol%, more preferably 60.0-77.5mol%. The molar percentage Cmol% of the component derived from (C) adipic acid is preferably 1.5-19.0mol%, more preferably 2.0-17.5mol%.

[0017] The above molar percentages Amol%, Bmol%, and Cmol% are the ester compounds. 1 The values ​​were calculated after analyzing by H-NMR to determine the molar amounts of the constituent components derived from each raw material. Below 1 The H-NMR measurement conditions are as follows.

[0018] <Measurement conditions> ·Analytical equipment: 1 H-NMR (400MHz) Solvent: deuterated chloroform

[0019] The ester compound obtained under the above measurement conditions 1 The molar amount can be calculated by analyzing the H-NMR chart. Specifically, the following four peaks are used: Peak (I): 3.40-3.70 ppm = (A) Hydrogen at the α-position of the unreacted hydroxyl group of pentaerythritol Peak (II): 4.00-4.20 ppm = (A) Hydrogen at the α-position of the reacted hydroxyl group of pentaerythritol {8 hydrogen atoms in total for peaks (I) and (II)} Peak (III): 0.85-0.90 ppm = (B) Hydrogen (3) attached to the terminal carbon of linear saturated fatty acid with 14-24 carbon atoms Peak (IV): 2.25-2.35 ppm = (C) 4 hydrogen atoms at the α-position of the carbonyl group of adipic acid and (B) 2 hydrogen atoms at the α-position of the carbonyl group of straight-chain fatty acids with 14 to 22 carbon atoms

[0020] The integral values ​​of the above four peaks are calculated as follows, and these are taken as the molar amounts A mol, B mol, and C mol of each component derived from each raw material. Amol = {Integral value of peak (I) + Integral value of peak (II)} / 8 Bmol = integral value of peak (III) / 3 Cmol={Integral value of peak (IV)-(Bmol×2)} / 4

[0021] The molar percentages Amol%, Bmol%, and Cmol% are calculated from the molar amounts Amol, Bmol, and Cmol obtained above as follows. Amol%=100×Amol / (Amol+Bmol+Cmol) Bmol%=100×Bmol / (Amol+Bmol+Cmol) Cmol%=100×Cmol / (Amol+Bmol+Cmol)

[0022] The molecular weight of the ester compound in the present invention can be measured by gel permeation chromatography (GPC). The molecular weight of the ester compound in the present invention is preferably in the range of 2000 to 3500 as the number average molecular weight of the polyester compound converted into monodisperse polystyrene. Within this number average molecular weight range, it is possible to achieve both low temperature fixability and excellent storage stability of the toner.

[0023] From the viewpoint of storage stability, the ester compound in the present invention preferably has an acid value of 5 mgKOH / g or less, more preferably 3 mgKOH / g or less, and particularly preferably 1 mgKOH / g or less. From the viewpoint of storage stability, the hydroxyl value is preferably 20 mgKOH / g or less, more preferably 15 mgKOH / g or less, and particularly preferably 10 mgKOH / g or less. The acid value can be measured in accordance with JOCS (Japan Oil Chemists' Society) 2.3.1-1996, and the hydroxyl value can be measured in accordance with JOCS (Japan Oil Chemists' Society) 2.3.6.2-1996.

[0024] The ester compound in the present invention can impart low-temperature fixing properties to the toner since it is capable of lowering the softening temperature of the resin, and furthermore, since it has a large molecular weight and high viscosity, it can impart excellent storage stability to the toner. The melting point of the ester compound in the present invention is preferably 60 to 90° C., more preferably 65 to 85° C. If the melting point is less than 60° C., storage stability deteriorates, and if it is higher than 90° C., low-temperature fixability cannot be imparted to the toner. The melting point of the ester can be measured by differential scanning calorimetry (DSC) at a heating rate of 10° C. per minute, and the temperature of the top peak of the endothermic peak measured by DSC analysis can be taken as the melting point.

[0025] Examples of the method for producing the ester compound of the present invention include a production method utilizing a dehydration condensation reaction between pentaerythritol, which is a raw material for the alcohol component, and a linear saturated fatty acid having 14 to 24 carbon atoms and adipic acid, which are raw materials for the acid component; a reaction between pentaerythritol and an acid halide of each of a linear saturated fatty acid having 14 to 24 carbon atoms and adipic acid; and a transesterification reaction between a first ester containing pentaerythritol as an alcohol component and a second ester containing a linear saturated fatty acid having 14 to 24 carbon atoms and adipic acid as acid components. A catalyst may be used in the reaction. Examples of such a catalyst include acidic or alkaline catalysts such as zinc acetate, titanium compounds, paratoluenesulfonic acid, and methanesulfonic acid. After the esterification reaction is completed, the reaction product may be highly purified by a recrystallization method, a distillation method, a solvent extraction method or the like.

[0026] The toner wax of the present invention is blended with a binder resin, a colorant, a charge control agent, etc., and a toner is produced by a conventional manufacturing method. The blending amount of the toner wax of the present invention in the toner is preferably 0.1 to 15 parts by mass per 100 parts by mass of the binder resin. The toner wax of the present invention is blended alone or in combination of two or more kinds.

[0027] The binder resin is not particularly limited, and any of those conventionally used as binder resins for toners, such as styrene resin, acrylic ester resin, styrene-acrylic ester copolymer resin, polyester resin, polyvinyl chloride resin, polyvinyl acetate resin, phenol resin, and epoxy resin, can be used. The colorant is not particularly limited, and any of those conventionally used as toner colorants, such as carbon black, magnetic powder, and pigments of various colors, can be used. EXAMPLES

[0028] Next, the present invention will be described in more detail by showing examples and comparative examples. 1. Wax preparation example The compositions, acid values, hydroxyl values, number average molecular weights Mn and melting points of the toner waxes used in the examples and comparative examples are shown in Table 1. The preparation method of each wax shown in Table 1 is as follows.

[0029] [Preparation of wax a] In a 3 L four-neck flask equipped with a thermometer, a nitrogen inlet tube, a stirring blade, and a cooling tube, 280 g (2.06 mol) of pentaerythritol, 119.9 g (0.82 mol) of adipic acid, 1955.2 g (6.87 mol) of stearic acid, and 2.36 g (0.01 mol) of paratoluenesulfonic acid were added and reacted under a nitrogen stream at 220° C. The obtained crude ester product weighed 2215.5 g and had an acid value of 7.5 mgKOH / g. To the crude ester product, 700 g of toluene and 150 g of 2-propanol were added, and a 10% by mass aqueous potassium hydroxide solution containing potassium hydroxide in an amount equivalent to 2.0 times the residual acid value of the crude ester product was added, followed by stirring at 70°C for 30 minutes. The mixture was then left to stand for 30 minutes, after which the aqueous layer (lower layer) was separated and removed. The mixture was washed with water four times until the pH of the wastewater became neutral. The solvent in the remaining ester layer was distilled off under reduced pressure conditions of 180°C and 1 kPa, and filtration was performed to obtain 2060.4 g of wax a. The yield relative to the crude ester product subjected to deacidification was 93%.

[0030] [Preparation of wax b] In a 3 L four-neck flask equipped with a thermometer, a nitrogen inlet tube, a stirring blade, and a cooling tube, 280 g (2.06 mol) of pentaerythritol, 119.9 g (0.82 mol) of adipic acid, and 1955.2 g (6.87 mol) of stearic acid were added and reacted under a nitrogen stream at 220° C. The obtained crude ester product weighed 2211.8 g and had an acid value of 11.5 mg KOH / g. To the crude ester product, 700 g of toluene and 150 g of 2-propanol were added, and a 10% by mass aqueous potassium hydroxide solution containing potassium hydroxide in an amount equivalent to 2.0 times the residual acid value of the crude ester product was added, followed by stirring at 70°C for 30 minutes. The mixture was then left to stand for 30 minutes, after which the aqueous layer (lower layer) was separated and removed. The mixture was washed with water four times until the pH of the wastewater became neutral. The solvent in the remaining ester layer was distilled off under reduced pressure conditions of 180°C and 1 kPa, and filtration was performed to obtain 2057.5 g of wax b. The yield relative to the crude ester product subjected to deacidification was 93%.

[0031] [Preparation of waxes c-g and j-l] Waxes c to g and j to l shown in Table 1 were obtained in the same manner as in the preparation of wax a above, except that the raw materials were used in different amounts. [Preparation of wax h] Wax h was obtained using palmitic acid as the straight-chain saturated fatty acid and the preparation procedure was the same as for wax a. [Preparation of wax i] Wax i was obtained using behenic acid as the linear saturated fatty acid and the preparation procedure was the same as for wax a.

[0032] [Preparation of Pentaerythritol Tetrastearate (PETS) Wax] In a 3 L four-neck flask equipped with a thermometer, a nitrogen inlet tube, a stirring blade, and a cooling tube, 280 g (2.06 mol) of pentaerythritol and 1955.2 g (6.87 mol) of stearic acid were added and reacted under a nitrogen stream at 220° C. The obtained crude ester product weighed 2640.3 g and had an acid value of 8.7 mg KOH / g. To the crude ester product, 750 g of toluene and 200 g of 2-propanol were added, and a 10% by mass aqueous potassium hydroxide solution containing potassium hydroxide in an amount equivalent to 2.0 times the residual acid value of the crude ester product was added, followed by stirring at 70°C for 30 minutes. The mixture was then left to stand for 30 minutes, after which the aqueous layer (lower layer) was separated and removed. The mixture was washed with water four times until the pH of the wastewater became neutral. The solvent in the remaining ester layer was distilled off under reduced pressure conditions of 180°C and 1 kPa, and filtration was performed to obtain 2520.7 g of PETS wax. The yield relative to the crude ester product subjected to deacidification was 95%.

[0033] [Table 1]

[0034] 2. Evaluation Method The methods of measurements and evaluations carried out in the examples and comparative examples are as follows. 2-1. Measurement of wax composition and physical properties (1) Molar percentages of each component in the wax: Amol%, Bmol%, Cmol% For each wax, 1 H-NMR analysis was carried out under the following measurement conditions. 1 The H-NMR chart was analyzed to determine the molar amount of each component derived from each raw material. Based on the obtained molar amount, the molar percentages Amol%, Bmol%, and Cmol% of each component in the wax were calculated using the above formula. <Measurement conditions> ·Analytical equipment: 1 H-NMR (400MHz) Solvent: deuterated chloroform

[0035] (2) Acid value of wax Measurements were performed in accordance with JOCS (Japan Oil Chemists' Society) 2.3.1-1996. (3) Hydroxyl value of wax Measurements were performed in accordance with JOCS (Japan Oil Chemists' Society) 2.3.6.2-1996.

[0036] (4) Number average molecular weight of wax The gel permeation chromatography (GPC) measurement device used was an "HLC-8320 GPC EcoSEC (manufactured by Tosoh Corporation)." The number average molecular weight of the wax was measured using THF as the eluent, a measurement temperature of 40°C, and polystyrene as the standard substance.

[0037] (5) Melting point of wax The differential scanning calorimeter used was a DSC-7000X manufactured by Hitachi High-Tech Science Corporation. The measurements were performed by placing approximately 10 mg of the ester in a sample holder and using 10 mg of alumina as a reference material, and heating the sample from 30°C to 150°C at a heating rate of 10°C per minute. The sample used for the measurements was one that had been subjected to a heating process from 30°C to 150°C and a cooling process from 150°C to 30°C prior to the measurements. The temperature of the top peak of the endothermic peak measured by the DSC was determined as the melting point of the wax.

[0038] 2-2. Wax performance evaluation (1) Lowering the resin melting temperature The effect of lowering the melting temperature when wax is mixed with a binder resin was evaluated by the following method. Evaluation samples were prepared for each of Examples 1 to 9 and Comparative Examples 1 to 4. Specifically, 95 parts by mass of polyester resin (product name: Diaclone ER-508, manufactured by Mitsubishi Rayon Co., Ltd.) and 5 parts by mass of the wax shown in Table 2 were mixed, and melt-kneaded using a twin-screw kneader "Labo Plastomill" (manufactured by Toyo Seiki Co., Ltd.) to obtain a resin kneaded product. The melt-kneading was performed at 120°C and 80 rpm / min for about 5 minutes, and the obtained resin kneaded product was pulverized and molded into particles with a particle size of 100 μm or less to obtain an evaluation sample. In addition, a resin kneaded material containing polyester resin but not wax was pulverized and molded into particles having a particle size of 100 μm or less to prepare a blank sample. For each evaluation sample and blank sample, 1 g of the sample was molded into a cylindrical shape with a diameter of 1 cm and a height of 1 cm, and the 1 / 2 melting temperature was measured using a flow tester (CFT-500EX: manufactured by Shimadzu Corporation) under conditions of a heating rate of 2°C / min and a load of 20 kg. Measurements were performed three times for each sample and the average value was calculated, and the measured average value T of each evaluation sample and the measured average value Tblank of the blank sample were obtained. The 1 / 2 melting temperature (1 / 2T) is calculated by the following formula (1) using the measured average value T of the evaluation sample and the measured average value Tblank of the blank sample. The higher the value of the half melting temperature calculated in this manner, the better the low-temperature fixing ability is evaluated to be. Calculation formula (1): 1 / 2T=Tblank-T

[0039] (2) Storage stability in resin The storage stability when the wax was mixed with the binder resin was evaluated by the following method. In order to evaluate the storage stability in the resin, the evaluation samples of Examples 1 to 9 and Comparative Examples 1 to 4 prepared in the above evaluation of the effect of lowering the resin melting temperature were used. For each evaluation sample, 5 g of the resin kneaded sample is placed in a glass vial and left to stand in a thermostatic bath maintained at 45°C for 2 weeks. The vial is then turned upside down and the sample is removed without applying force. When the mass of the sample that flows out without being deposited in the vial and whose particle size is maintained at 100 μm or less is taken as X, the blocking resistance rate R is calculated by the following formula (2). Calculation formula (2): R=X(g) / 5(g) The calculated blocking resistance rate R was used to evaluate storage stability in accordance with the following evaluation criteria. The larger the value of the blocking resistance rate R calculated in this way, the more excellent the storage stability is evaluated to be. The values ​​shown in parentheses in Table 2 are the calculated values ​​of the blocking resistance rate R. <Evaluation criteria> 〇 (Excellent): Blocking resistance rate R 0.85 or less △(Good): 0.75<Blocking resistance rate R<0.85 × (bad): 0.75 or more blocking resistance rate R

[0040] (3) Improved color development The color development improving effect of the wax was evaluated by the following method. Evaluation samples were prepared for each of Examples 1 to 9 and Comparative Examples 1 to 4. Specifically, 94 parts by mass of polyester resin (product name: Diacron ER-508, manufactured by Mitsubishi Rayon Co., Ltd.), 5 parts by mass of the wax shown in Table 2, and 1 part by mass of colorant (product name: PV-FAST BLUE BG, manufactured by Clariant Co., Ltd.) were mixed, and melt-kneaded using a twin-screw kneader (product name: "Labo Plastomill", manufactured by Toyo Seiki Co., Ltd.) to obtain a resin kneaded product. The melt-kneading was performed at 120°C and 80 rpm / min for about 5 minutes, and the obtained resin kneaded product was molded into a smooth plate (100 x 100 mm) using a hot press machine to obtain an evaluation sample. In addition, a smooth plate-shaped molded product containing 99 parts by mass of polyester resin and 1 part by mass of colorant but no wax was prepared as a blank sample. The surface of each evaluation sample was measured in reflection mode using a color difference meter (ZE6000, manufactured by Nippon Denshoku Industries Co., Ltd.) and the color difference was measured according to CIE1976 (L * ,a * ,b * ) Color development for each hue in the color space (so-called CIELAB) * , b * Using the obtained measurements, the chroma C of the evaluation sample was calculated using the following formula (3). A blank sample was also similarly measured using a color difference meter to calculate the chroma Cblank of the blank sample. Calculation formula (3): C=(a *2 +b *2 ) 1 / 2 The color development improvement rate Kc is calculated by the following formula (4) using the chroma C of the evaluation sample and the chroma Cblank of the blank sample. The larger the value of the color development improvement rate Kc calculated in this way, the more excellent the color development improvement effect is evaluated to be. Calculation formula (4): Kc=C / Cblank

[0041] 3. Evaluation results For the above examples and comparative examples, the compositions and physical properties of the wax itself are shown in Table 1, and the compositions of the samples used to evaluate the performance of the wax as a toner material and the results of the performance evaluation are shown in Table 2.

[0042] [Table 2]

[0043] The waxes a to i used in Examples 1 to 9 have melting points in the range of 60° C. to 90° C., and by lowering the melting temperature of the resin, it is possible to impart low-temperature fixability to the toner, and since the blocking resistance rate R is high, the toner has excellent storage stability during storage. Furthermore, since the color development improvement rate Kc is Kc>1, it is possible to improve the color development of the toner.

[0044] On the other hand, in Comparative Example 1, in which the molar percentage Cmol% of the constituents derived from adipic acid is 0mol%, i.e., pentaerythritol tetrastearate (PETS) alone is used, the melting temperature is half that of the Examples, so that the toner cannot be given sufficient low-temperature fixing properties. Also, the color development improvement rate Kc is Kc<1, so there is no effect of improving color development when used as a toner wax. In Comparative Example 2, in which wax j having a molar percentage Bmol% of components derived from linear saturated acids higher than the range of the present invention was used, the blocking resistance rate R was lower than in the Examples, the storage stability in the toner was deteriorated, and the color development improvement rate Kc was Kc<1, meaning that there was no effect of improving color development. In Comparative Example 3, which used wax k in which the molar percentage (Amol%) of the constituent component derived from pentaerythritol was higher than the range of the present invention, the blocking resistance R was low and the storage stability was deteriorated. In Comparative Example 4, which used wax 1 in which the molar percentage C mol % of the constituent component derived from adipic acid was higher than the range of the present invention, the blocking resistance R was low and the storage stability was deteriorated.

Claims

[Claim 1] A toner wax comprising an ester compound having (A) a molar percentage A mol% of a component derived from pentaerythritol of 19.0 to 25.0 mol%, (B) a molar percentage B mol% of a component derived from a linear saturated fatty acid having 14 to 24 carbon atoms of 55.0 to 80.5 mol%, and (C) a molar percentage C mol% of a component derived from adipic acid of 0.50 to 20.0 mol%.

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