Method for suppressing deterioration in storage stability of toner and improving low-temperature fixability and color rendering of toner

Abstract

Provided is a method for suppressing deterioration in storage stability of a toner and improving low-temperature fixability and color rendering properties of the toner using a wax for the toner, the method being capable of imparting low-temperature fixability to the toner, and exhibiting excellent storage stability in the toner, the image quality of a toner printed matter can be improved by improving the color rendering property of the toner. The toner wax is composed of an ester compound in which the molar fraction (Amol%) of a constituent component derived from (A) pentaerythritol is 19.0-25.0 mol%, the molar fraction (Bmol%) of a constituent component derived from (B) a linear saturated fatty acid having 14-24 carbon atoms is 55.0-80.5 mol%, and the molar fraction (Cmol%) of a constituent component derived from (C) adipic acid is 0.50-20.0 mol%.

Description

[0001] The present invention is a divisional application of the Chinese patent application with application number 202110612808.5, application date June 2, 2021, and invention name “Wax for Colorant”. This application claims the priority of Japanese Patent Application No. 2020-102917 filed in Japan on June 15, 2020. Technical Field

[0002] The present invention relates to a wax for toner, which is suitable for use in a toner for a recording method for developing an electrostatic charge image such as an electrophotographic method or an electrostatic recording method in an image forming apparatus such as a copier or a laser printer. Background Art

[0003] The toner used in image forming devices such as copiers and printers contains a colorant (carbon black, magnetic powder, pigment, etc.), a charge regulator, and wax in a thermoplastic resin as a binder resin, and further contains a fluidity additive, a cleaning aid, and a transfer aid as needed.

[0004] Among them, wax has the function of preventing toner from remaining on the fixing roller (filming) during fixing and promoting the softening of thermoplastic resin to improve the fixing property. In recent years, due to the improvement of environmental awareness around the world, the low-temperature fixing property of toner has been paid attention to in order to reduce power consumption. Wax has a low melting point, and it is sought to improve the low-temperature fixing property of toner by lowering the melting temperature of thermoplastic resin.

[0005] On the other hand, since the wax oozes out excessively on the surface of the molten colorant, it sometimes adheres to the fixing components such as the fixing roller and the fixing belt, which may cause poor image quality. In addition, since the wax oozes out during the storage of the colorant, it becomes a major cause of the adhesion of the colorant particles to each other. Therefore, research has been conducted on using high molecular weight synthetic multifunctional ester waxes that are not easy to ooze out during the storage of the colorant to improve the storage stability of the colorant.

[0006] Furthermore, in recent years, with the popularization of print on demand digital printing in the commercial printing field, printed materials with high-resolution image output and unprecedented metallic style printed materials have appeared. As a result, the demand for toners with good color development has increased, and a material that contributes to high color development has been sought.

[0007] For example, Patent Document 1 discloses a toner using a multifunctional 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 multifunctional polyester waxes have excellent low-temperature fixing properties and storage stability. However, when the wax of Patent Document 1 is used, the color development property of the toner cannot be improved.

[0008] Furthermore, Patent Document 2 describes a method for producing an ester wax for a toner, characterized in that a linear saturated monocarboxylic acid selected from carbon atoms having 14 to 30 or a mixture thereof, a linear saturated monohydric alcohol selected from carbon atoms having 14 to 30 or a mixture thereof, or a divalent to hexavalent polyhydric alcohol selected from carbon atoms having 2 to 30 or a mixture thereof is subjected to a condensation reaction, then neutralized with an alkaline aqueous solution, and the neutralized salt is removed by centrifugal separation. Patent Document 2 also describes that by using the wax, a toner having excellent low-temperature fixing property and storage stability can be provided. However, when the wax of Patent Document 2 is used, the color development property of the toner cannot be improved.

[0009] Prior art literature

[0010] Patent Literature

[0011] Patent Document 1: Japanese Patent Application Laid-Open No. 7-98511

[0012] Patent Document 2: Japanese Patent Application Laid-Open No. 2012-32479 Summary of the invention

[0013] 1. Technical issues to be resolved

[0014] An object of the present invention is to provide a wax for toner which can impart low-temperature fixing property to toner, exhibit excellent storage stability in toner, and contribute to high-quality toner prints by improving the color development property of toner.

[0015] (II) Technical solution

[0016] The inventors of the present invention have conducted intensive studies to solve the above-mentioned technical problems, and as a result, have found that when an ester compound containing a constituent component derived from (A) pentaerythritol, a constituent component derived from (B) a linear saturated fatty acid having 14 to 24 carbon atoms, and a constituent component derived from (C) adipic acid in a specific ratio is used as a toner wax, it is possible to impart low-temperature fixing property to the toner, exhibit excellent storage stability in the toner, and contribute to high-quality image printing of toner prints by improving the color development property of the toner, thereby completing the present invention.

[0017] That is, the wax composition for colorant of the present invention is characterized in that it is composed of an ester compound, in which the molar percentage A mol% of the constituent derived from (A) pentaerythritol is 19.0~25.0 mol%, the molar percentage B mol% of the constituent derived from (B) a straight-chain saturated fatty acid having 14 to 24 carbon atoms is 55.0~80.5 mol%, and the molar percentage C mol% of the constituent derived from (C) adipic acid is 0.50~20.0 mol%.

[0018] (III) Beneficial effects

[0019] The wax for toner of the present invention can provide a toner with low-temperature fixability, exhibit excellent storage stability in the toner, and contribute to high-quality toner prints by improving the color development of the toner. DETAILED DESCRIPTION

[0020] The following describes the embodiments of the present invention. In addition, in this specification, the numerical range specified by the symbol "~" includes the numerical values ​​at both ends (upper limit and lower limit) of the "~". For example, "2~5" means 2 or more and 5 or less.

[0021] The toner wax of the present invention is an ester compound containing (A) a constituent derived from pentaerythritol as an alcohol component, (B) a constituent derived from a linear saturated fatty acid having 14 to 24 carbon atoms as a first acid component, and (C) a constituent derived from adipic acid as a second acid component.

[0022] It is considered that when an ester compound containing a component derived from (A) pentaerythritol, a component derived from (B) a linear saturated fatty acid having 14 to 24 carbon atoms, and a component derived from (C) adipic acid in a specific ratio is used as a toner wax, the compatibility with the binder resin is appropriately improved and the compatibility with the colorant is also improved.

[0023] It is believed that since the compatibility of the wax to the binder resin is appropriately increased, the toner can be given low-temperature fixability by lowering the softening temperature of the resin, and it is not easy to ooze out in the toner, thereby showing excellent storage stability. In addition, it is believed that since the compatibility of the wax to the colorant is also high, it will not hinder the dispersion of the colorant, thereby improving the color development of the toner. It is also believed that while having low-temperature fixability and storage stability, by improving the color development of the toner, it helps to achieve high image quality of toner prints.

[0024] As the raw material derived from the constituent components of (A) pentaerythritol as the alcohol component, pentaerythritol or a pentaerythritol derivative that can give the same structural unit as pentaerythritol in the ester synthesis reaction can be used.

[0025] Since pentaerythritol is a neopentyl polyol with a neopentyl skeleton, it has excellent oxidation stability and heat resistance. As other neopentyl polyols, neopentyl glycol, trimethylolpropane, and dipentaerythritol can be listed. However, when neopentyl glycol and trimethylolpropane are used as alcohol components, there is a possibility that the melting point of the obtained ester decreases significantly and the storage stability in the toner deteriorates, and when dipentaerythritol is used as the alcohol component, there is a possibility that the viscosity increases significantly and the low-temperature fixability becomes insufficient. Therefore, the neopentyl polyol used in the present invention is preferably pentaerythritol.

[0026] As the raw material of the constituent component derived from (B) a linear saturated fatty acid having 14 to 24 carbon atoms as the first acid component, a linear saturated fatty acid having 14 to 24 carbon atoms or a fatty acid derivative that can give the same structural unit as the linear saturated fatty acid having 14 to 24 carbon atoms in the ester synthesis reaction can be used.

[0027] As the linear saturated fatty acid having 14 to 24 carbon atoms used in the present invention, for example, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, lignoic acid, etc. can be cited. In the present invention, a mixed carboxylic acid containing two or more of these monovalent linear saturated carboxylic acids can be used. Among the above linear saturated fatty acids, palmitic acid, stearic acid, arachidic acid, behenic acid are preferred, and stearic acid, arachidic acid, behenic acid are particularly preferred.

[0028] When the carbon number is less than 14, the melting point may decrease and the storage stability in the toner may deteriorate. On the other hand, when the carbon number is more than 24, the low-temperature fixing property may be insufficiently imparted.

[0029] As the raw material derived from the constituent component of (C) adipic acid as the second acid component, adipic acid which is a dicarboxylic acid or an adipic acid derivative which can give the same structural unit as that of adipic acid in an ester synthesis reaction can be used.

[0030] When succinic acid or the like having a smaller carbon number than adipic acid is used as the dicarboxylic acid, the heat resistance may be significantly deteriorated. In addition, when sebacic acid or the like having a larger carbon number than adipic acid is used, the melting point may be significantly lowered, and the storage stability in the toner may be deteriorated.

[0031] The toner wax of the present invention is composed of an ester compound, wherein the molar percentage Amol% of the constituent component derived from (A) pentaerythritol is 19.0-25.0mol%, the molar percentage Bmol% of the constituent component derived from (B) a linear saturated fatty acid having 14-24 carbon atoms is 55.0-80.5mol%, and the molar percentage Cmol% of the constituent component derived from (C) adipic acid is 0.50-20.0mol%. When the content ratio of the components (A), (B) and (C) is outside the above range, the low temperature fixing property and the storage stability of the toner may become insufficient, and the effect of improving the color development property of the toner cannot be obtained.

[0032] From the above perspectives, the molar percentage Amol% of the constituents derived from (A) pentaerythritol is preferably 20.0-24.0mol%, and more preferably 20.5-22.5mol%. In addition, the molar percentage Bmol% of the constituents derived from (B) straight-chain saturated fatty acids having 14 to 24 carbon atoms is preferably 57.5-78.5mol%, and more preferably 60.0-77.5mol%. In addition, the molar percentage Cmol% of the constituents derived from (C) adipic acid is preferably 1.5-19.0mol%, and more preferably 2.0-17.5mol%.

[0033] The above molar percentages Amol%, Bmol%, and Cmol% are determined by 1 The value is calculated by analyzing the ester compound with H-NMR and determining the molar amount of the constituent components derived from each raw material.

[0034] The following shows 1 H-NMR measurement conditions.

[0035] <Measurement Conditions>

[0036] Analytical instruments: 1 H-NMR (400MHz)

[0037] Solvent: deuterated chloroform

[0038] By measuring the ester compound obtained under the above measurement conditions 1 The molar amount can be determined by analyzing the H-NMR chart. Specifically, the following four peaks are used.

[0039] Peak (I): 3.40~3.70ppm = (A) unreacted hydroxyl group α-hydrogen

[0040] Peak (II): 4.00~4.20ppm = (A) Hydrogen at the α position of the reacted hydroxyl group of pentaerythritol {Peak (I) and Peak (II) total 8}

[0041] Peak (III): 0.85-0.90 ppm = hydrogen (3) bonded to the terminal carbon of (B) straight-chain saturated fatty acid with 14-24 carbon atoms

[0042] Peak (IV): 2.25-2.35 ppm = (C) α-position hydrogen of the carbonyl group of adipic acid (4 atoms) and (B) α-position hydrogen of the carbonyl group of a straight-chain fatty acid with 14-22 carbon atoms (2 atoms)

[0043] The integrated values ​​of the above four peaks were calculated as follows to obtain the molar amounts A mol, B mol, and C mol of the respective components derived from the respective raw materials.

[0044] Amol={integral value of peak (I) + integral value of peak (II)} / 8

[0045] Bmol = integrated value of peak (III) / 3

[0046] Cmol={integral value of peak (IV)-(Bmol×2)} / 4

[0047] The molar percentages Amol%, Bmol%, and Cmol% were calculated from the molar amounts Amol, Bmol, and Cmol obtained above in the following manner.

[0048] Amol%=100×Amol / (Amol+Bmol+Cmol)

[0049] Bmol%=100×Bmol / (Amol+Bmol+Cmol)

[0050] Cmol%=100×Cmol / (Amol+Bmol+Cmol)

[0051] 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, based on the number average molecular weight of the monodisperse polystyrene conversion of the polyester compound. Within this number average molecular weight range, both the imparting of low-temperature fixability and the excellent storage stability of the toner can be achieved.

[0052] From the viewpoint of storage stability, the acid value of the ester compound in the present invention is preferably 5 mgKOH / g or less, more preferably 3 mgKOH / g or less, and particularly preferably 1 mgKOH / g or less.

[0053] Furthermore, 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.

[0054] The acid value can be measured in accordance with JOCS (Japan Oil Chemistry Society) 2.3.1-1996, and the hydroxyl value can be measured in accordance with JOCS (Japan Oil Chemistry Society) 2.3.6.2-1996.

[0055] The ester compound in the present invention can lower the softening temperature of the resin and thus can impart low-temperature fixability to the toner, and can impart excellent storage stability to the toner because of its large molecular weight and high viscosity.

[0056] 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 lower than 60° C., the storage stability is poor, while if the melting point is higher than 90° C., low-temperature fixing property cannot be imparted to the toner.

[0057] The melting point of the ester can be measured by differential scanning calorimetry (DSC) at a temperature increase rate of 10° C. per minute, and the temperature of the top of the endothermic peak measured by DSC analysis can be taken as the melting point.

[0058] Examples of methods for producing the ester compound of the present invention include a method utilizing a dehydration condensation reaction of pentaerythritol as an alcohol component raw material and a linear saturated fatty acid having 14 to 24 carbon atoms and adipic acid as an acid component raw material, a reaction of pentaerythritol with acid halides of a linear saturated fatty acid having 14 to 24 carbon atoms and adipic acid, and an ester exchange reaction of a first ester containing pentaerythritol as an alcohol component with a second ester containing a linear saturated fatty acid having 14 to 24 carbon atoms and adipic acid as an acid component.

[0059] A catalyst may be used during the reaction. Examples of the catalyst include acidic and basic catalysts, such as zinc acetate, titanium compounds, p-toluenesulfonic acid, and methanesulfonic acid.

[0060] After the esterification reaction is completed, the obtained reaction product can be highly purified by recrystallization, distillation, solvent extraction, etc.

[0061] The toner wax of the present invention is blended with a binder resin, a colorant, a charge regulator, etc., and a toner is produced by a conventional method. The blending amount of the toner wax of the present invention in the toner is preferably 0.1 to 15 parts by mass relative to 100 parts by mass of the binder resin. One or more of the toner waxes of the present invention may be blended in the toner.

[0062] The binder resin is not particularly limited, and any binder resin conventionally used as a binder resin for toner can be used, for example, styrene resin, acrylate resin, styrene-acrylate copolymer resin, polyester resin, polyvinyl chloride resin, polyvinyl acetate resin, phenol resin, epoxy resin, etc. can be used.

[0063] The colorant is not particularly limited, and colorants conventionally used as toner colorants can be used, such as carbon black, magnetic powder, and pigments of various colors.

[0064] Example

[0065] Next, the present invention will be described in further detail by showing examples and comparative examples.

[0066] 1. Wax Preparation Example

[0067] The composition, acid value, hydroxyl value, number average molecular weight Mn and melting point of the toner wax used in Examples and Comparative Examples are shown in Table 1. The preparation methods of the various waxes shown in Table 1 are as follows.

[0068] [Preparation of wax a]

[0069] In a 3L four-necked flask equipped with a thermometer, a nitrogen inlet tube, a stirring blade and a cooling tube, 280g (2.06mol) of pentaerythritol, 119.9g (0.82mol) of adipic acid, 1955.2g (6.87mol) of stearic acid and 2.36g (0.01mol) of p-toluenesulfonic acid were added and reacted at 220°C under a nitrogen stream. The crude ester product obtained was 2215.5g and the acid value was 7.5mgKOH / g.

[0070] To the crude ester, add 700 g of toluene and 150 g of 2-propanol, add a 10% by mass potassium hydroxide aqueous solution containing 2.0 times the equivalent of the residual acid value of the crude ester, and stir at 70°C for 30 minutes. Then, let it stand for 30 minutes, separate and remove the water layer (lower layer). Repeat washing 4 times until the pH of the discharged water is neutral. Under reduced pressure conditions of 180°C and 1 kPa, distill off the solvent of the residual ester layer, and filter to obtain 2060.4 g of wax a. The yield of the crude esterification product for deacidification is 93%.

[0071] [Preparation of wax b]

[0072] In a 3L four-necked flask equipped with a thermometer, a nitrogen inlet tube, a stirring blade and a cooling tube, 280g (2.06mol) of pentaerythritol, 119.9g (0.82mol) of adipic acid and 1955.2g (6.87mol) of stearic acid were added and reacted at 220°C under a nitrogen stream. The crude ester product obtained was 2211.8g and the acid value was 11.5mgKOH / g.

[0073] 700 g of toluene and 150 g of 2-propanol were added to the crude ester product, and a 10% by mass potassium hydroxide aqueous solution containing 2.0 equivalents of potassium hydroxide corresponding to the residual acid value of the crude ester product was added, and stirred at 70°C for 30 minutes. Then, the mixture was allowed to stand for 30 minutes, and the aqueous layer (lower layer) was separated and removed. The washing was repeated 4 times until the pH of the discharged water was neutral. Under reduced pressure conditions of 180°C and 1 kPa, the solvent of the residual ester layer was distilled off and filtered to obtain 2057.5 g of wax b. The yield of the crude esterified product for deacidification was 93%.

[0074] [Preparation of waxes c~g and j~l]

[0075] Waxes c to g and j to l shown in Table 1 were obtained by the same procedure except that the same raw materials as those used in the preparation of wax a were used and the amounts of raw materials added were changed.

[0076] [Preparation of wax h]

[0077] Palmitic acid was used as the straight-chain saturated fatty acid and wax h was obtained by the same preparation steps as wax a.

[0078] [Preparation of wax i]

[0079] Behenic acid was used as the straight-chain saturated fatty acid and wax i was obtained by the same preparation steps as wax a.

[0080] [Preparation of Pentaerythritol Tetrastearate (PETS) Wax]

[0081] In a 3L four-necked 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 the mixture was reacted at 220° C. under a nitrogen flow. The crude ester product obtained was 2640.3 g and had an acid value of 8.7 mgKOH / g.

[0082] 750 g of toluene and 200 g of 2-propanol were added to the crude ester product, and a 10% by mass potassium hydroxide aqueous solution containing 2.0 times the equivalent of the residual acid value of the crude ester product was added, and stirred at 70°C for 30 minutes. Then, the mixture was allowed to stand for 30 minutes, and the aqueous layer (lower layer) was separated and removed. The washing was repeated 4 times until the pH of the discharged water was neutral. Under reduced pressure conditions of 180°C and 1 kPa, the solvent of the residual ester layer was distilled off and filtered to obtain 2520.7 g of PETS wax. The yield of the crude esterified product for deacidification was 95%.

[0083] [Table 1]

[0084]

[0085] 2. Evaluation Method

[0086] The methods of various measurements and evaluations performed in Examples and Comparative Examples are as follows.

[0087] 2-1. Determination of wax composition and physical properties

[0088] (1) Mole percentage of each component in the wax: Amol%, Bmol%, Cmol%

[0089] For each wax, the following measurement conditions were used. 1 H-NMR analysis showed that 1 The molar amount of the constituent components from each raw material was determined by analyzing the H-NMR chart. Based on the obtained molar amount, the molar percentage Amol%, Bmol%, and Cmol% of each constituent component in the wax was calculated using the above calculation formula.

[0090] <Measurement Conditions>

[0091] Analytical instruments: 1 H-NMR (400MHz)

[0092] Solvent: deuterated chloroform

[0093] (2) Acid value of wax

[0094] The measurement was carried out in accordance with JOCS (Japan Oil Chemistry Society) 2.3.1-1996.

[0095] (3) Hydroxyl value of wax

[0096] The measurement was carried out in accordance with JOCS (Japan Oil Chemistry Society) 2.3.6.2-1996.

[0097] (4) Number average molecular weight of wax

[0098] "HC-8320 GPC EcoSEC (manufactured by TOSOH CORPORATION)" was used as a measuring apparatus for gel permeation chromatography (GPC), THF was used as an eluent, the measuring temperature was set to 40°C, and polystyrene was used as a standard substance to measure the number average molecular weight of the wax.

[0099] (5) Melting point of wax

[0100] A "DSC-7000X" manufactured by Hitachi High-Tech Science Corporation was used as a differential scanning calorimeter. About 10 mg of ester was added to a sample holder, 10 mg of aluminum oxide was used as a standard substance, and the temperature was raised from 30°C to 150°C at a heating rate of 10°C per minute. In addition, before the measurement, a sample that had undergone a heating process from 30°C to 150°C and a cooling process from 150°C to 30°C was used as a measurement sample.

[0101] The temperature of the top of the endothermic peak measured by the above DSC was defined as the melting point of the wax.

[0102] 2-2. Evaluation of wax performance

[0103] (1) Effect of lowering the melting temperature of resin

[0104] The effect of lowering the melting temperature when wax is mixed with the binder resin was evaluated by the following method.

[0105] Evaluation samples were prepared for Examples 1 to 9 and Comparative Examples 1 to 4, respectively. Specifically, 95 parts by mass of a polyester resin (product name: Diacron ER-508, manufactured by MITSUBISHI RAYON CO., LTD.) and 5 parts by mass of a wax shown in Table 2 were mixed, and melt-kneaded using a twin-screw kneading machine "LABO PLASTOMILL" (manufactured by TOYOSEKI) 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 a particle size of 100 μm or less to serve as an evaluation sample.

[0106] In addition, a resin kneaded product containing a polyester resin but not containing wax was pulverized and molded into particles with a diameter of 100 μm or less to serve as a blank sample.

[0107] For these evaluation samples and blank samples, 1 g of the sample was molded into a cylindrical shape of 1 cm in diameter and 1 cm in height, and the 1 / 2 melting temperature was measured using a rheometer (CFT-500EX: manufactured by Shimadzu Corporation) at a heating rate of 2°C / min and a load of 20 kg. For each sample, the measurement was performed 3 times, and the average value was calculated to obtain the measurement average value T of each evaluation sample and the measurement average value T of the blank sample.

[0108] The 1 / 2 melting temperature (1 / 2T) was calculated by the following calculation formula (1) using the measured average value T of the evaluation sample and the measured average value Tblank of the blank sample.

[0109] The larger the value of the 1 / 2 melting temperature calculated in this way is, the more excellent the low-temperature fixing property is evaluated to be.

[0110] Calculation formula (1): 1 / 2T = T blank - T

[0111] (2) Storage stability in resin

[0112] The storage stability when wax was mixed with the binder resin was evaluated by the following method.

[0113] 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 evaluation of the effect of lowering the melting temperature of the resin were used.

[0114] For these evaluation samples, 5 g of the resin kneaded product as the evaluation sample was placed in a glass vial, and the mixture was left to stand in a thermostatic chamber maintained at 45° C. for 2 weeks. The glass vial was inverted, and when the sample was taken out without applying any force, the mass of the sample that did not settle in the vial but flowed out and whose particle size was kept below 100 μm was set as X. At this time, the anti-blocking rate R was calculated by the following calculation formula (2).

[0115] Calculation formula (2): R = X (g) / 5 (g)

[0116] The calculated anti-blocking rate R was evaluated for storage stability with reference to the following evaluation criteria. The larger the value of the calculated anti-blocking rate R, the more excellent the storage stability was evaluated. In addition, the numerical values ​​shown in brackets in Table 2 are the values ​​of the calculated anti-blocking rate R.

[0117] <Evaluation Criteria>

[0118] 0(Excellent): 0.85≤anti-adhesion rate R

[0119] △(good): 0.75<anti-blocking rate R<0.85

[0120] ×(bad): 0.75≥anti-adhesion rate R

[0121] (3) Color rendering improvement effect

[0122] The color development improving effect of the wax was evaluated by the following method.

[0123] Evaluation samples were prepared for Examples 1 to 9 and Comparative Examples 1 to 4, respectively. Specifically, 94 parts by mass of a polyester resin (product name: Diacron ER-508, manufactured by MITSUBISHI RAYON CO., LTD.), 5 parts by mass of a wax shown in Table 2, and 1 part by mass of a colorant (product name: PV-FAST BLUE BG, manufactured by Clariant) were mixed and melt-kneaded using a biaxial kneading machine (product name "LABO PLASTOMILL", manufactured by TOYO SEKI 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 shape (100×100 mm) by a hot press to prepare an evaluation sample.

[0124] In addition, a smooth plate-shaped molded product containing 99 parts by mass of a polyester resin and 1 part by mass of a colorant but not containing wax was prepared as a blank sample.

[0125] For these evaluation samples, the sample surface was measured in the reflection mode using a colorimeter (colorimeter ZE6000, manufactured by Nippon Denshoku Industries Co., Ltd.) to obtain CIE1976 (L ＊ , a ＊ , b ＊ ) color space (the so-called CIELAB) ＊ , b ＊ The value below. Using the obtained measured value, the chroma C of the evaluation sample is calculated by the following calculation formula (3). The blank sample is also measured in the same manner using a colorimeter to calculate the chroma C blank of the blank sample.

[0126] Calculation formula (3): C = (a ＊2 +b ＊2 ) 1 / 2

[0127] The color rendering improvement rate Kc is calculated by the following calculation formula (4) using the chroma C of the evaluation sample and the chroma C blank of the blank sample. The larger the value of the color rendering improvement rate Kc thus calculated, the more excellent the color rendering improvement effect is evaluated.

[0128] Calculation formula (4): Kc = C / C blank

[0129] 3. Evaluation results

[0130] Regarding the above Examples and Comparative Examples, the composition and physical properties of the wax itself are shown in Table 1, and Table 2 shows the composition of the samples used for the performance evaluation of the wax as a toner material and the results of the performance evaluation.

[0131] [Table 2]

[0132]

[0133] The melting points of the waxes a to i used in Examples 1 to 9 are in the range of 60°C to 90°C. By lowering the melting temperature of the resin, the toner can be given low-temperature fixability, and the anti-blocking rate R is also high, so the storage stability in the toner during storage is also excellent. Furthermore, since the color development improvement rate Kc is Kc>1, the color development of the toner can be improved.

[0134] On the other hand, in Comparative Example 1, in which the molar percentage Cmol% of the constituent component derived from adipic acid was 0mol%, that is, pentaerythritol tetrastearate (PETS) monomer was used, the 1 / 2 melting temperature was lower than that of the examples, and thus the toner could not be sufficiently provided with low-temperature fixing property. Furthermore, the color development improvement rate Kc was Kc<1, and when used as a toner wax, there was no effect of improving the color development.

[0135] For Comparative Example 2 using wax j in which the molar percentage Bmol% of the constituent components derived from a straight-chain saturated acid is higher than the range of the present invention, compared with the embodiment, the anti-blocking rate R is low, the storage stability in the colorant is deteriorated, and the color development improvement rate Kc is Kc<1, and there is no effect of improving the color development.

[0136] In Comparative Example 3 using wax k in which the molar percentage A mol % of the constituent component derived from pentaerythritol exceeded the range of the present invention, the anti-blocking ratio R was low and the storage stability was poor.

[0137] 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 anti-blocking ratio R was low and the storage stability was poor.

Claims

1. A method for suppressing the deterioration of the storage stability of a toner and improving the low-temperature fixing property and color developing property of the toner, characterized in that: The method uses a toner wax, wherein the toner wax is composed of an ester compound, wherein the molar percentage Amol% of a constituent derived from (A) pentaerythritol is 19.0-25.0mol%, the molar percentage Bmol% of a constituent derived from (B) a straight-chain saturated fatty acid having 14-24 carbon atoms is 55.0-80.5mol%, and the molar percentage Cmol% of a constituent derived from (C) adipic acid is 0.50-20.0mol%.

2. The method according to claim 1, wherein: The molar percentage A mol % of the constituent derived from (A) pentaerythritol is 20.1-22.0 mol %, the molar percentage B mol % of the constituent derived from (B) straight-chain saturated fatty acids having 14-24 carbon atoms is 69.2-78.8 mol %, and the molar percentage C mol % of the constituent derived from (C) adipic acid is 0.8-8.8 mol %.

3. The method according to claim 1 or 2, wherein: The ester compound has an acid value of 1 mgKOH / g or less and a hydroxyl value of 10 mgKOH / g or less.

4. The method according to claim 1 or 2, wherein: The constituent derived from the (B) straight-chain saturated fatty acid having 14 to 24 carbon atoms is a constituent derived from a straight-chain saturated fatty acid having 18 to 22 carbon atoms.

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