Wax composition for toner

Abstract

To provide a wax composition for toner that ensures high storage stability within toner, suppresses gloss unevenness in printed materials during high-speed printing, and can improve glossiness.SOLUTION: A wax composition for toner comprises an ester compound A represented by the structural formula (1) and an aliphatic ketone compound B represented by the structural formula (2), with the mass ratio between the ester compound A and the aliphatic ketone compound B [(A): (B)] of 0.1:99.9 to 30:70. [Structural formula (1): HO-(CH2)n-O-C(=O)-R1] (R1 is a C15-24 linear saturated alkyl group, and n represents an integer of 2-6). [Structural formula (2): R2-C(=O)-R3] (R2 and R3 independently represent a linear alkyl group, and the total number of carbon atoms in R2 and R3 is 30-48).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a wax composition for toner that is suitably used for developing electrostatic images recorded by electrophotography or electrostatic recording methods in photocopiers, laser printers, and the like. [Background technology]

[0002] Toner used in image forming devices such as photocopiers and printers contains a thermoplastic resin that serves as a binder resin, a coloring agent (such as carbon black, magnetic powder, or pigment), a charge control agent, and a wax, and optionally further contains a fluidity enhancer, a cleaning aid, and a transfer aid. In this context, the wax functions as a release agent to prevent toner from remaining on the fixing roll during fixing (filming), and also has the function of promoting the softening of the thermoplastic resin to improve fixing performance.

[0003] On the other hand, wax can cause toner particles to block each other due to bleeding during toner storage, so efforts are being made to improve the storage stability of the toner. For example, Patent Document 1 describes a method for producing an ester wax for toner, characterized by a condensation reaction between a linear saturated monocarboxylic acid or a mixture thereof selected from among those having 14 to 30 carbon atoms, a linear saturated monohydric alcohol or a mixture thereof selected from among those having 14 to 30 carbon atoms, or a dihydric to hexahydric polyhydric alcohol or a mixture thereof selected from among those having 2 to 30 carbon atoms, followed by neutralization with an alkaline aqueous solution and removal of the neutralized salt by centrifugation. It is stated that using this wax provides a toner with excellent storage stability.

[0004] Furthermore, in recent years, copying devices such as multifunction printers and commercial printing presses have required toners that can handle ultra-high-speed printing beyond conventional limits, from the perspective of improving production efficiency and saving energy. For example, Patent Document 2 describes that by mixing hydrocarbon wax and ester wax, a toner can be obtained that has excellent low-temperature fixing and fixing / separation properties, is less likely to cause mold release agent to adhere to components of image forming equipment, and can form images with excellent scratch resistance. It is expected that using such a toner will also enable high-speed printing.

[0005] Furthermore, in the commercial printing field where these devices are used, there is a need to consistently provide high-quality printed materials with a uniform, high gloss equivalent to or better than photographs and posters obtained by silver halide photography or gravure printing, even under the aforementioned ultra-high-speed printing conditions. However, wax presents a challenge because differences in the crystalline state on the surface of the printed material can cause uneven gloss, and there is a need for wax that can solve these problems. For example, Patent Document 3 introduces a toner using synthetic monoester wax as an electrophotographic toner that exhibits high gloss close to photographic gloss over a wide fixing temperature range, and achieves excellent low-temperature fixing properties, high resistance to hot offsets, and good storage stability. However, even such toners are not sufficiently compatible with ultra-high-speed printing and cannot reduce gloss unevenness in printed materials.

[0006] Furthermore, Patent Document 4 introduces a toner that uses an ester wax in which the difference between the endothermic peak temperature during heating and the exothermic peak temperature during cooling, i.e., the difference between the melting point and the solidification point, is within a specific range, thereby adjusting the affinity between the wax and the polyester resin binder, and consequently suppressing the amount of wax bleeding during image fixing and enabling the suppression of gloss unevenness caused by the wax. However, even when using such a wax, it is not sufficient to suppress gloss unevenness due to differences in crystalline state, and the amount of wax bleeding may be insufficient during high-speed printing. Also, because the difference between the melting point and the solidification point is large, there is a risk that the melting and solidification of the wax will be insufficient, and it cannot be said that high-quality printed materials can be stably supplied. Thus, there are many required characteristics for toner, and a wax for toner that can satisfy these required characteristics simultaneously is demanded.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0008] An object of the present invention is to provide a wax composition for toner that has excellent storage stability in toner, suppresses gloss unevenness of printed matter even during high-speed printing, and can improve glossiness.

Means for Solving the Problems

[0009] As a result of intensive studies to solve the above problems, the present inventors have found that when a composition containing an ester compound A and an aliphatic ketone compound B shown below in a specific ratio is used as a wax for toner, it is possible to provide a wax composition for toner that has excellent storage stability in toner, suppresses gloss unevenness of printed matter even during high-speed printing, and can improve glossiness, and thus have completed the present invention.

[0010] That is, the wax composition for toner of the present invention contains an ester compound A represented by the following structural formula (1) and an aliphatic ketone compound B represented by the following structural formula (2), and the mass ratio [(A):(B)] of the ester compound A to the aliphatic ketone compound B is 0.1:99.9 to 30:70. Ester compound A:

[0011] [ka]

[0012] (R in structural formula (1)) 1 (where n represents a linear saturated alkyl group with 15-24 carbon atoms, and n is an integer between 2 and 6.) Aliphatic ketone compound B:

[0013] [ka]

[0014] (In structural formula (2), R 2 and R 3 Each of these independently represents a linear alkyl group, and R 2 and R 3 The total number of carbon atoms is between 30 and 48. [Effects of the Invention]

[0015] The wax composition for toner of the present invention exhibits excellent storage stability in toner, and can suppress uneven gloss of printed materials and improve gloss even during high-speed printing. [Modes for carrying out the invention]

[0016] Embodiments of the present invention will be described below. The wax composition for toner of the present invention contains, as essential components, ester compound A and aliphatic ketone compound B as shown below. In this specification, numerical ranges defined using the symbol "~" include the numbers at both ends (upper and lower limits) of "~". For example, "2~5" means 2 or more and 5 or less.

[0017] [Ester compound A] Ester compound A in the present invention is a monoester compound obtained from at least one linear saturated monocarboxylic acid selected from linear saturated monocarboxylic acids having 16 to 25 carbon atoms and at least one aliphatic alcohol selected from linear saturated alkylene glycols having 2 to 6 carbon atoms, and is represented by the following structural formula (1).

[0018] [ka]

[0019] (R in the structural formula) 1 (where n represents a linear saturated alkyl group with 15-24 carbon atoms, and n is an integer between 2 and 6.)

[0020] The starting carboxylic acid for ester compound A is a straight-chain saturated monocarboxylic acid having 16 to 25 carbon atoms, preferably 18 to 22. If the starting carboxylic acid has too few carbon atoms, the wax may melt at low temperatures, significantly reducing its storage stability in the toner. On the other hand, if the number of carbon atoms is too large, the dispersibility of the wax in the toner may deteriorate, negatively affecting storage stability. Specific examples of raw material carboxylic acids include palmitic acid, stearic acid, arachidic acid, and behenic acid. Among these, stearic acid is particularly preferred.

[0021] The raw material alcohol for ester compound A is a linear saturated alkylene glycol having 2 to 6 carbon atoms, preferably 2 to 4. If the number of carbon atoms is outside this range, the melting point of the wax will decrease significantly, potentially impairing its storage stability. Furthermore, if the alkyl group of the raw material alcohol has a branched structure, such as 1,2-propanediol, or if it is a trivalent or higher alcohol, such as glycerin or pentaerythritol, when blended with the aliphatic ketone compound B described later, it can significantly reduce the crystallinity of the wax, making it difficult to use for high-speed printing, and may also cause uneven gloss due to the crystalline state of the wax. From this perspective, specific examples of raw material alcohols include ethylene glycol, 1,4-butanediol, and 1,6-hexanediol. Among these, ethylene glycol and 1,4-butanediol are particularly preferred. The ester compound A obtained from the above-mentioned linear saturated monocarboxylic acid and the above-mentioned linear saturated alkylene glycol preferably has a total number of carbon atoms of 20 to 26, and more preferably has a total number of carbon atoms of 20 to 24, and among these, a monoester compound consisting of stearic acid and ethylene glycol is preferred.

[0022] From the viewpoint of storage stability, ester compound A preferably has an acid value of 5 mg KOH / g or less, more preferably 3 mg KOH / g or less, and particularly preferably 1 mg KOH / g or less. Furthermore, from the viewpoint of suppressing gloss unevenness during high-speed printing, a hydroxyl value of 140 mg KOH / g to 190 mg KOH / g is preferred, and even more preferably 160 mg KOH / g to 180 mg KOH / g. 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.

[0023] The melting point of ester compound A is preferably 60°C to 80°C, and more preferably 65°C to 75°C. If the melting point is below 60°C, storage stability may deteriorate, and if it is above 80°C, it may not dissolve during high-speed printing and may not exhibit its effect as a toner wax. The melting point of ester compound A can be measured by differential scanning calorimetry (DSC) with 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.

[0024] [Aliphatic ketone compound B] The aliphatic ketone compound B in the present invention is an aliphatic ketone compound having 31 to 49 carbon atoms in total and is represented by the following structural formula (2).

[0025] [Chemical formula]

[0026] (In structural formula (2), R 2 and R 3 each independently represent a linear alkyl group, and the total number of carbon atoms of R 2 and R 3 is 30 to 48.)

[0027] In the above structural formula (2), the linear alkyl groups R 2 and R 3 are each independently preferably 15 or more and 23 or less carbon atoms, more preferably 17 or more and 21 or less carbon atoms, from the viewpoints of storage stability and compatibility with high-speed printing. If the number of carbon atoms of the linear saturated aliphatic hydrocarbon group is less than 15, there is a risk of causing blocking between toners by bleeding during toner storage. On the other hand, if the number of carbon atoms of the linear saturated aliphatic hydrocarbon group exceeds 23, the melting point becomes too high, and there is a risk that the function as a release agent during high-speed printing becomes insufficient. Specific examples of the aliphatic ketone compound represented by structural formula (2) include dipentadecyl ketone, dihexadecyl ketone, diheptadecyl ketone, dioctadecyl ketone, dinonadecyl ketone, dieicosyl ketone, diheneicosyl ketone, didocosyl ketone, ditricosyl ketone, ditetracosyl ketone.

[0028] Aliphatic ketone compound B can be obtained by reacting a carboxylic acid having the aforementioned linear saturated aliphatic hydrocarbon group with a metal oxide catalyst at a high temperature, preferably 300-350°C, and a high pressure, preferably 0.1-5 MPa, and decarboxylating. Examples of metal oxide catalysts include magnesium oxide, calcium oxide, and zinc oxide, and examples of carboxylic acids include palmitic acid, margaric acid, stearic acid, arachidic acid, behenic acid, and lignoceric acid. Alternatively, instead of the aforementioned carboxylic acid having the linear saturated aliphatic hydrocarbon group and the metal oxide catalyst, metal carboxylic acid salts such as magnesium carboxylate salts, calcium carboxylate salts, and zinc carboxylate salts may be used. Representative examples include magnesium stearate, calcium stearate, zinc stearate, magnesium behenate, calcium behenate, and zinc behenate. From the viewpoint of storage stability, the acid value of aliphatic ketone compound B is preferably 5 mg KOH / g or less, more preferably 3 mg KOH / g or less, and particularly preferably 1 mg KOH / g or less. The acid value can be measured in accordance with JOCS (Japan Oil Chemists' Society) 2.3.1-1996.

[0029] The melting point of aliphatic ketone compound B is preferably 70 to 100°C, and more preferably 80 to 100°C. If the melting point is below 70°C, storage stability may deteriorate, and if it is above 100°C, it may not melt during high-speed printing and may not exhibit its effect as a toner wax. The melting point of aliphatic ketone compound B 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 defined as the melting point.

[0030] [Wax composition for toner] The wax composition for toner of the present invention contains the above-mentioned ester compound A and aliphatic ketone compound B, and the mass ratio of ester compound A to aliphatic ketone compound B [(A):(B)] is 0.1:99.9 to 30:70, preferably 1:99 to 15:85. If the mass ratio of ester compound A to aliphatic ketone compound B does not satisfy 0.1:99.9 to 30:70, the effects of the present invention cannot be obtained, and if it satisfies 1:99 to 15:85, the effects of the present invention can be obtained more significantly.

[0031] From the viewpoint of suppressing uneven gloss during high-speed printing, the toner wax composition of the present invention preferably exhibits small differences in crystallization behavior caused by differences in cooling rate. As an indicator of this, the crystallization enthalpy ΔH when the toner wax composition is slowly cooled from a molten state is used. S And the crystallization enthalpy ΔH when rapidly cooled from a molten state. R Ratio (ΔH R / ΔH S ) is preferably 0.75 or higher, more preferably 0.80 or higher, and particularly more preferably 0.85 or higher. In this invention, the crystallization enthalpy ΔH when the toner wax composition is slowly cooled from a molten state is defined. S This involves calculating the integral value of the exothermic peak during the cooling from 180°C to 30°C using differential scanning calorimetry (DSC) at a cooling rate of 2°C per minute, and then using the obtained integral value as ΔH S Furthermore, the crystallization enthalpy ΔH when rapidly cooled from a molten state was determined. R This involves calculating the integral value of the exothermic peak during the cooling from 180°C to 30°C using differential scanning calorimetry (DSC) at a cooling rate of 10°C per minute, and then using the obtained integral value as ΔH S That's what I decided.

[0032] The toner wax composition of the present invention can be manufactured by known methods. For example, it may be manufactured by synthesizing ester compound A and aliphatic ketone compound B separately and then combining them to produce a toner wax. Alternatively, it may be manufactured by adjusting the amount of synthetic materials so that the mass ratio (A):(B) of ester compound A to aliphatic ketone compound B falls within the above range, and then manufacturing it in a single synthesis. In a method for producing a toner wax composition by synthesizing and then combining ester compound A and aliphatic ketone compound B, it is preferable from the viewpoint of minimizing variations in quality to heat ester compound A and aliphatic ketone compound B above their melting points, then uniformly mix them, and then cool, atomize, etc.

[0033] The toner wax composition of the present invention is blended with a binder resin, a colorant, a charge control agent, etc., and toner is manufactured by a conventional method. The amount of the toner wax composition of the present invention blended into the toner is usually 1 to 10 parts by mass per 100 parts by mass of binder resin. The toner wax composition of the present invention is blended into the toner alone or in a mixture of two or more types. [Examples]

[0034] The present invention will be further explained below by showing an example of the production of the wax composition for toner of the present invention and a method for evaluating it.

[0035] [Example of preparation of ester compound A] Table 1 shows the acid value, hydroxyl value, and melting point of ester compound A used in the examples and comparative examples. [Preparation of ester compound A-1] In a 3 L four-necked flask equipped with a thermometer, nitrogen inlet tube, stirring blade, and condenser, 800.0 g (12.9 mol) of ethylene glycol and 1834.6 g (6.4 mol) of stearic acid were added. The mixture was reacted at 200 °C under a nitrogen stream, and then the reaction was carried out by distillation at 250 °C under reduced pressure of 30 kPa. The resulting crude ester product was 2058.0 g with an acid value of 2.0 mg KOH / g. 500 g of the crude ester product was completely dissolved in a mixed solvent of 1000 g of heptane and 1000 g of 2-propanol at 70°C, and then recrystallized by slow cooling. The resulting precipitate was collected by filtration. After repeating the recrystallization procedure three times, the collected precipitate was vacuum-dried at 40°C to obtain 200 g of ester compound A-1.

[0036] [Preparation example of ester compound A-2] Ester compound A-2, shown in Table 1, was obtained using 1,4-butanediol as the linear saturated alkylene glycol, and following the same procedure as for ester compound A-1, except that the amount of raw materials used was changed. [Preparation example of ester compound A-3] Ester compound A-3, shown in Table 1, was obtained using 1,6-hexanediol as the linear saturated alkylene glycol, and following the same procedure as for ester compound A-1, except that the amount of raw materials used was changed. [Preparation example of ester compound A-4] Ester compound A-4, shown in Table 1, was obtained using the same procedure as for ester compound A-1, except that behenic acid was used as the straight-chain saturated fatty acid and the amount of raw materials used was changed. [Preparation example of ester compound A-5] Ester compound A-5, shown in Table 1, was obtained using the same procedure as for ester compound A-1, except that palmitic acid was used as the straight-chain saturated fatty acid and the amount of raw materials used was changed. [Preparation example of ester compound A-6] Ester compound A-6, shown in Table 1, was obtained using 1,10-decanediol as the linear saturated alkylene glycol, and following the same procedure as for ester compound A-1, except that the amount of raw materials used was changed. [Preparation example of ester compound A-7] Ester compound A-7, shown in Table 1, was obtained using the same procedure as for ester compound A-1, except that glycerin was used instead of linear saturated alkylene glycol and the amount of raw materials used was changed.

[0037] [Table 1]

[0038] [Example of preparation of aliphatic ketone compound B] Table 2 shows the acid value and melting point of aliphatic ketone compound B used in the examples and comparative examples. [Example of preparation of aliphatic ketone compound B-1] 700.0 g (1.18 mol) of magnesium stearate [product name Nissan Electrol MM-2, manufactured by NOF Corporation, magnesium stearate, stearic acid content: 98%] was weighed into a 1 L stainless steel separable flask, and the temperature was raised to 250°C by blowing nitrogen. At this time, the water contained in the material was distilled out of the system. Then, nitrogen was injected under a pressure of 2 MPa, the temperature was raised to 340-350°C, and the reaction was continued for 8 hours, after which it was cooled to 100°C to obtain a crude aliphatic ketone compound. The aliphatic ketone compound was filtered through a 100 mesh metal strainer at 100°C under nitrogen blowing, and the magnesium oxide produced as a by-product was filtered out. The wax obtained by filtering was then discharged into a stainless steel tray, solidified at room temperature, and pulverized in a mixer. The obtained aliphatic ketone compound B-1 (diheptadecyl ketone; R 2 and R 3 The acid value of (total carbon number = 34) was 0.2 mg KOH / g, and the transparent melting point was 85.8°C.

[0039] [Preparation example of aliphatic ketone compound B-2] 600.0 g (1.8 mol) of behenic acid [behenic acid manufactured by NOF Corporation, behenic acid content: 97%, acid value = 164.9 mg KOH / g] and 35.6 g (0.9 mol) of magnesium oxide were weighed into a 1 L stainless steel separable flask, and the temperature was raised to 250°C by blowing in nitrogen. At this time, the water contained in the materials was distilled out of the system. Then, nitrogen was injected under a pressure of 2 MPa, the temperature was raised to 340-350°C, and the reaction was continued for 8 hours, after which it was cooled to 100°C to obtain a crude aliphatic ketone compound. The aliphatic ketone compound was filtered through a 100 mesh metal strainer at 100°C under nitrogen blowing, and the magnesium oxide produced as a by-product was filtered out. The wax obtained by filtering was discharged into a stainless steel tray, solidified at room temperature, and then pulverized in a mixer. The obtained aliphatic ketone compound B-2 (diheneicosylketone; R 2 and R 3 The acid value of (total carbon number = 42) was 0.4 mg KOH / g, and the transparent melting point was 94.5°C.

[0040] [Example of preparation of aliphatic ketone compound B-3] 600.0 g (2.2 mol) of stearic acid [Bead Stearic Acid Sakura, manufactured by NOF Corporation, a mixture of stearic acid and palmitic acid (mass ratio 65 / 35), acid value = 207.8 mg KOH / g] and 44.4 g (1.01 mol) of magnesium oxide were weighed into a 1 L stainless steel separable flask, and the temperature was raised to 250°C by blowing in nitrogen. At this time, the water contained in the materials was distilled out of the system. Then, nitrogen was injected under a pressure of 2 MPa, and the temperature was further raised to 340-350°C, and the reaction was continued for 8 hours, after which it was cooled to 100°C to obtain a crude aliphatic ketone compound. The aliphatic ketone compound was filtered through a 100 mesh metal strainer at 100°C under nitrogen blowing, and the magnesium oxide produced as a by-product was filtered out. The wax obtained by filtering was discharged into a stainless steel tray, solidified at room temperature, and then pulverized in a mixer. The resulting aliphatic ketone compound B-3 (a mixture of diheptadecylketone / dipentadecylketone / pentadecylheptadecylketone; R 2 and R 3 The acid value of the compound with a total carbon number of carbon atoms (30-34) was 0.3 mg KOH / g, and its transparent melting point was 78.4°C. Furthermore, GC analysis revealed that the mass ratio of the aliphatic ketone mixture was diheptadecylketone / dipentadecylketone / pentadecylheptadecylketone = 42 / 13 / 45.

[0041] [Table 2]

[0042] [Example of preparation of wax composition for toner] Table 3 shows the composition of the wax compositions used in the examples and comparative examples, and the crystallization enthalpy ΔH during slow cooling from the molten state. S and crystallization enthalpy ΔH during rapid cooling R Ratio (ΔH R / ΔH S This shows the following preparation method. In a 0.3 L separable flask equipped with a stirring blade and a nitrogen inlet tube, ester compound A and aliphatic ketone compound B were melt-mixed in the mass ratio shown in Table 3, and stirred at 150°C for 1 hour under a nitrogen stream. Subsequently, the mixture was cooled, solidified, and ground to obtain a wax composition for toner.

[0043] [Table 3]

[0044] [Evaluation Method] The various tests and evaluation methods used in the examples and comparative examples are as follows:

[0045] [Testing of ester compound A and aliphatic ketone compound B] (1) Measurement of acid value Measurements were taken in accordance with JOCS (Japan Oil Chemists' Society) 2.3.1-1996. (2) Measurement of hydroxyl value Measurements were taken in accordance with JOCS (Japan Oil Chemists' Society) 2.3.6.2-1996.

[0046] (3) Measurement of melting point A differential scanning calorimetry (DSC-7000X) manufactured by Hitachi High-Tech Science Corporation was used as the differential scanning calorimetry (DSC-7000X). Measurements were performed by placing approximately 10 mg of ester compound A or aliphatic ketone compound B into a sample holder, using 10 mg of alumina as the reference material, and heating from 30°C to 180°C at a heating rate of 10°C per minute. Prior to measurement, samples that had undergone a heating process from 30°C to 180°C and a cooling process from 180°C to 30°C were used as the measurement samples. The temperature of the top peak of the endothermic peak measured by the DSC was defined as the melting point of ester compound A and aliphatic ketone compound B.

[0047] [Measuring the enthalpy of crystallization and ratio (ΔH) of wax compositions for toners] R / ΔH S ) Calculation] The crystallization enthalpy was measured when the toner wax composition was slowly or rapidly cooled from a molten state using the same apparatus and procedure as described in "(3) Measurement of Melting Point" above. Crystallization enthalpy ΔH during slow cooling S The integral value of the exothermic peak of the toner wax composition during the cooling from 180°C to 30°C was calculated using differential scanning calorimetry (DSC) at a cooling rate of 2°C per minute, and the obtained integral value was used as ΔH. S This was also stated. Furthermore, the crystallization enthalpy ΔH during rapid cooling. R This involves calculating the integral value of the exothermic peak of the toner wax composition during the cooling process from 180°C to 30°C using differential scanning calorimetry (DSC) at a cooling rate of 10°C per minute, and then determining the obtained integral value as ΔH S The measured values ​​obtained were used to determine the crystallization enthalpy (ΔH) during slow cooling. S ) and crystallization enthalpy (ΔH) during rapid cooling R ) ratio (ΔH R / ΔH S ) was calculated.

[0048] [Evaluation of wax compositions for toners] (1) Storage stability of wax composition for toner The storage stability of the wax composition when mixed with the binder resin was evaluated using the following method. Evaluation samples were prepared for each of Examples 1 to 9 and Comparative Examples 1 to 5. Specifically, 95 parts by mass of polyester resin (product name: Diacron ER-508, manufactured by Mitsubishi Rayon Co., Ltd.) and 5 parts by mass of the wax composition shown in Table 3 were mixed, and melt kneading was performed using a twin-screw kneader "Laboplastmill" (manufactured by Toyo Seiki Co., Ltd.) to obtain a resin mixture. Melt kneading was performed at 120°C and 80 rpm / min for about 5 minutes, and the obtained resin mixture was pulverized and molded to a particle size of 50 μm or less to be used as an evaluation sample. For each evaluation sample, 5g of the resin mixture was placed in a glass vial and left to stand in a constant temperature bath maintained at 45°C for two weeks. The vial was then inverted, and the sample was removed without applying any force. When the sample was removed, if the mass of the sample that flowed out without depositing in the vial and whose particle size remained 50 μm or less was denoted as X, the blocking resistance rate R was calculated using the following formula (I). Calculation formula (I): R=X(g) / 5(g) The calculated blocking resistance ratio R was used to evaluate storage stability against the following criteria. A higher value for the blocking resistance ratio R indicates superior storage stability. <Evaluation Criteria> ◎ (Exhibits excellent storage stability): 0.95 ≤ R ○ (Indicates excellent storage stability): 0.90 <R<0.95 × (Insufficient storage stability): 0.90≧R

[0049] (2) High-speed printing response of wax composition for toner During high-speed printing, wax compositions need to melt and solidify quickly; therefore, it is preferable that the difference between the melting and solidifying points ΔT of the wax composition is small. In this invention, the difference between the melting and solidifying points ΔT of the wax composition was calculated, and the responsiveness of the wax composition to high-speed printing was evaluated using ΔT as an indicator. Specifically, a differential scanning calorimetry analyzer, "DSC-7000X" manufactured by Hitachi High-Tech Science Corporation, was used. The measurement was performed by placing approximately 10 mg of wax composition in a sample holder and using 10 mg of alumina as a reference material. The temperature was raised from 30°C to 180°C at a heating rate of 10°C per minute, and then cooled from 180°C to 30°C. Prior to measurement, a sample that had undergone the heating process from 30°C to 180°C and the cooling process from 180°C to 30°C was used as the measurement sample. The temperature of the top peak of the endothermic peak during heating, measured by the above DSC, was defined as the melting temperature (Tpm), and the temperature of the top peak of the exothermic peak during cooling was defined as the solidification temperature (Tec). Using the melting temperature (Tpm) and solidification temperature (Tec) of the obtained toner wax composition, the difference ΔT between the melting temperature and solidification temperature was calculated using the following formula (II). Calculation formula (II): ΔT=Tpm-Tec Based on the calculated ΔT value, the responsiveness of the wax composition to high-speed printing was evaluated according to the following criteria. <Evaluation Criteria> ◎(Also capable of ultra-high-speed printing): 12.0≧ΔT ○ (Suitable for high-speed printing): 12.0 < ΔT ≤ 15.0 × (Not suitable for high-speed printing): 15.0 < ΔT

[0050] (3) Gloss unevenness suppression effect of wax composition for toner The effect of suppressing gloss unevenness during high-speed printing was evaluated using the following method. For each of Examples 1-9 and Comparative Examples 1-5, 10 g of wax composition was melted at a temperature above its melting point. A 2 mm thick frame was placed between two 20 cm diameter metal plates with a mirror finish, the molten wax was poured into the frame, and the metal plates were used to sandwich the frame from above and below, allowing it to cool slowly or rapidly to create a wax plate. The resulting wax plates were measured using a Gloss Checker IG-320 manufactured by Horiba, Ltd., under conditions of an incident angle of 60°C (10 measurement areas were evaluated), and the average value was taken as the gloss value. The gloss value G during slow cooling was calculated using formula (III). S and gloss value G during rapid cooling R The smaller the absolute value ΔG of the difference, the better the effect of suppressing gloss unevenness is considered to be. Calculation formula (III): ΔG=|G R -G S | <Evaluation Criteria> ◎(Excellent at suppressing uneven gloss due to differences in cooling speed): 1.0≧ΔG ○ (Excellent at suppressing uneven gloss due to differences in cooling speed): 1.0 < ΔG ≤ 2.0 × (Poor at suppressing uneven gloss due to differences in cooling speed): 2.0 < ΔG

[0051] (4) Improving the gloss of wax compositions for toners The gloss-enhancing effect of the wax was evaluated using the following method. For each of Examples 1-9 and Comparative Examples 1-5, evaluation samples were prepared under rapid cooling conditions, similar to the evaluation of the gloss unevenness suppression effect described above, and the average gloss value G was calculated. r We sought the glossiness of the blank sample. Blank In this case, the gloss improvement rate K represents the gloss improvement effect caused by adding the wax composition. gThis can be calculated using the following formula (IV). The gloss improvement rate K calculated in this way g The higher the value, the better the gloss-enhancing effect is considered to be. Calculation formula (IV): K g =G r / G Blank <Evaluation Criteria> ◎ (Significantly improves gloss): 1.20 < Gloss improvement rate K g ○ (Improves gloss): 1.00 < Gloss improvement rate K g ≤1.20 × (No improvement in gloss): Gloss improvement rate K g ≤1.00

[0052] [Evaluation Results] The evaluation results for the above examples and comparative examples are shown in Tables 4 and 5.

[0053] [Table 4]

[0054] [Table 5]

[0055] Examples 1-9, using wax compositions W1-9, exhibit a high blocking resistance R, indicating excellent storage stability in toner during storage. Furthermore, wax compositions W1-9 have a small difference between their melting and freezing points, making them suitable for high-speed printing. In addition, the gloss value G during annealing is also high. S and gloss value G during rapid cooling R Since the absolute value of the difference ΔG is ΔG ≤ 2.0, it is possible to suppress uneven gloss of printed materials even during high-speed printing, and furthermore, the gloss improvement rate K g ga K g Since the value is >1.00, it can be said that the glossiness of printed materials can be improved. On the other hand, in Comparative Example 1, which used a wax composition W10 in which the number of carbon atoms n of the linear saturated alkylene glycol constituting ester compound A was greater than the range of the present invention, the effect of suppressing gloss unevenness was confirmed, but the storage stability deteriorated, the difference between the melting point and the freezing point of the wax composition was large and it could not be used for high-speed printing, and no effect of improving gloss was obtained. In Comparative Example 2, which used a wax composition W11 in which the alcohol constituting ester compound A is a trivalent alcohol, none of the effects achieved in the present invention were obtained. In Comparative Example 3, which used wax composition W12 that did not contain ester compound A, storage stability and responsiveness to high-speed printing were confirmed, but the effect of suppressing gloss unevenness and improving gloss was not obtained. In Comparative Example 4, which used a wax composition W13 with a higher proportion of ester compound A than that within the scope of the present invention, an improvement in glossiness was confirmed, but storage stability deteriorated, the difference between the melting point and freezing point of the wax composition was large, making it unsuitable for high-speed printing, and no effect of suppressing gloss unevenness was obtained. In Comparative Example 5, which used wax composition W14 that did not contain aliphatic ketone compound B, none of the effects of the present invention were obtained.

Claims

1. A wax composition for toner containing an ester compound A represented by the following structural formula (1) and an aliphatic ketone compound B represented by the following structural formula (2), wherein the mass ratio of ester compound A to aliphatic ketone compound B [(A):(B)] is 0.1:99.9 to 30:

70. Ester compound A: 【Chemistry 1】 (R in structural formula (1)) １ (where n represents a linear saturated alkyl group with 15 to 24 carbon atoms, and n represents an integer from 2 to 6.) Aliphatic ketone compound B: 【Chemistry 2】 (In structural formula (2), R ２ and R ３ Each of these independently represents a linear alkyl group, R ２ and R ３ The total number of carbon atoms is 30 to 48.

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