JP6149582B2 - Wax composition for toner - Google Patents

Description

  The present invention relates to a wax composition for a toner that is suitably used for developing an electrostatic image recorded by an electrophotographic method or an electrostatic recording method such as a copying machine or a laser printer.

The toners used in electrophotographic printers, facsimiles, and copiers having these functions include colorants (carbon black, magnetic powder, pigments, etc.), charge control agents, waxes in addition to thermoplastic resins as the main component. And a fluidity additive, a cleaning aid, and a transfer aid as necessary.
The toner is softened by being heated by a heat roll in the fixing step, and is fixed on the surface of the recording medium by receiving pressure from a pressure roll to form an image. The toner wax contained in the toner has a function of preventing the toner from remaining on the fixing roll (filming) at the time of fixing and promoting the softening of the thermoplastic resin to improve the fixing property.

Patent Documents 1 and 2 disclose toners using polypropylene wax or polyethylene wax as the toner wax.
However, due to the recent increase in environmental awareness, in order to reduce power consumption, copiers and the like have been demanded toners that support low-temperature fixing. For waxes, low-melting waxes that melt and function at low temperatures are required. It has been. Since the softening point of polypropylene wax or polyethylene wax is about 100 to 150 ° C. and does not melt at low temperatures, toners using these waxes have problems with low-temperature fixability.

Patent Document 3 discloses that as a method for improving the dispersibility of these synthetic waxes in a resin, a fatty acid metal salt having a fatty acid having 10 to 42 carbon atoms and selected from a zinc salt, a magnesium salt, and an aluminum salt. Discloses a method of adding 0.1 to 5 parts by weight of the resin to the resin.
However, this method is not sufficient for low-temperature fixability.

In recent years, fatty acid ester waxes have been used as low melting point waxes. Patent Document 4 discloses a method in which a monoester synthesized from a long-chain saturated fatty acid having about 6 to 39 carbon atoms and a long-chain saturated alcohol having about 5 to 28 carbon atoms is used as a toner wax.
However, although these monoester waxes are excellent in low-temperature fixability, the releasability of the toner from the heat roll may not be sufficient.

Patent Document 5 discloses fatty acid ester waxes having a polyfunctional polyester structure obtained from bifunctional or higher alcohol compounds or carboxylic acid compounds, and these ester waxes are excellent in releasability from a hot roll. It is disclosed.
Currently, electrophotographic printers are required to enable printing at a very high speed as compared with conventional printers such as high-speed printing and double-sided printing from the viewpoint of improving workability. In the wax for toner, it is necessary to quickly soften the resin and exhibit the releasability, and it is required to quickly solidify to prevent paper misalignment of the image quality and fusion between the papers.
However, the ester wax of Patent Document 5 has a very low freezing point as compared with the melting point, so that it is difficult to solidify during rapid cooling, and the wax does not solidify quickly during high-speed printing or double-sided printing, resulting in image quality variations and paper jams. There is a case.

  As described above, the toner wax composition used in the electrophotographic method, the electrostatic recording method, or the like can impart low-temperature fixability to the toner and achieve high image quality. Is required.

JP-A-5-53365 JP-A-6-324513 JP 2006-126529 A Japanese Patent Laid-Open No. 8-128304 JP-A-7-98511

  An object of the present invention is to solve the above-described problems, and to provide a wax composition for toner that can impart low-temperature fixability to a toner and can achieve high image quality.

As a result of diligent research to solve the above-mentioned problems, the present inventors have made a fatty acid ester wax having a specific structure and a fatty acid zinc salt having a specific structure into a molten mixture at a specific ratio. It has been found that the freezing point can be increased more and the temperature difference between the freezing point and the melting point can be reduced. The inventors have found that by using the wax composition as a wax for toner, excellent image quality can be achieved even during high-speed printing or double-sided printing, and the present invention has been completed.

That is, the present invention comprises a molten mixture of Compound A and Compound B shown below, wherein the mass ratio of Compound A to Compound B (A: B) is 99.7: 0.3 to 90:10, and The toner wax composition has a difference between the average carbon number of the linear saturated fatty acid constituting the compound A and the average carbon number of the linear saturated fatty acid of the compound B of 4 or less.
Compound A: Ester wax obtained from pentaerythritol or dipentaerythritol and monovalent linear saturated fatty acid having 14 to 24 carbon atoms Compound B: zinc salt of monovalent linear saturated fatty acid having 14 to 24 carbon atoms

  Since the toner wax composition of the present invention has a low melting point and is easily melted at a low temperature, it can impart low-temperature fixability to the toner. In addition, the freezing point can be increased and the temperature difference between the freezing point and the melting point can be reduced as compared with the case of the ester wax of Compound A alone. When used as a wax, good image quality performance can be obtained.

Embodiments of the present invention will be described below.
The wax composition for toner of the present invention comprises the following compound A and compound B.
In addition, the numerical value range prescribed | regulated using the symbol "~" in this specification shall contain the numerical value of the both ends (upper limit and lower limit) of "~". For example, “2 to 5” represents 2 or more and 5 or less.

[Compound A]
Compound A in the present invention is an ester wax obtained from a raw material alcohol and a monovalent linear saturated fatty acid.
As the raw material alcohol of Compound A, pentaerythritol or dipentaerythritol is used, and preferably pentaerythritol is used.
The monovalent linear saturated fatty acid of Compound A has 14 to 24 carbon atoms, preferably 16 to 24 carbon atoms, and more preferably 18 to 24 carbon atoms. When the number of carbon atoms of the monovalent linear saturated fatty acid of Compound A is less than 14, the melting temperature of Compound A is lowered and toner blocking may occur. On the other hand, when the number of carbon atoms exceeds 24, the oozing property to the toner surface at the time of melting Compound A may be inferior, and the releasability from the roll may be lowered. Examples of monovalent linear saturated fatty acids include myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, lignoceric acid and the like.

  Examples of the method for producing Compound A include a method utilizing a dehydration condensation reaction from an alcohol and a fatty acid. In the reaction, a catalyst may be used, and examples of the catalyst include acidic or basic catalysts such as titanium compounds and tin compounds. In the reaction, the fatty acid and the alcohol are added in an equimolar ratio, or one component is added in excess of the other component and reacted. Thereafter, it may be highly purified by a recrystallization method, a distillation method, a solvent extraction method, an adsorption treatment method, or the like.

In view of storage stability of the toner, the acid value of Compound A is preferably 5 mgKOH / g or less, and the hydroxyl value is preferably 10 mgKOH / g or less.
The acid value can be measured according to JOCS (Japan Oil Chemists' Society) 2.3.1-1996, and the hydroxyl value is determined according to JOCS (Japan Oil Chemical Society) 2.3.6-2-1996. Can be measured.

  The freezing point of Compound A is preferably 40 to 65 ° C., more preferably 45 to 60. The melting point of Compound A is preferably 60 to 90 ° C, more preferably 65 to 85. Moreover, 15-30 degreeC is preferable and, as for the temperature difference of melting | fusing point in a compound A and a freezing point, More preferably, it is 18-27. The freezing point and melting point of Compound A can be measured using a differential scanning calorimeter (DSC).

  As compound A, an ester wax using pentaerythritol and an ester wax using dipentaerythritol can be used in combination.

[Compound B]
Compound B in the present invention is a zinc salt of a monovalent linear saturated fatty acid. The monovalent linear saturated fatty acid has 14 to 24 carbon atoms, preferably 16 to 24 carbon atoms, and more preferably 18 to 24 carbon atoms. If the monovalent linear saturated fatty acid has less than 14 carbon atoms, the effect of reducing the temperature difference between the melting point and the freezing point may not be obtained.
Examples of monovalent linear saturated fatty acids include myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, lignoceric acid and the like.

[Wax composition for toner]
In the toner wax composition of the present invention, the mass ratio (A: B) between the compound A and the compound B satisfies the relationship of 99.7: 0.3 to 90:10. More preferably, the mass ratio (A: B) is 99.5: 0.5 to 92: 8, and still more preferably the mass ratio (A: B) is 99.5: 0.5 to 95: 5. When the mass ratio of Compound B is less than 0.3, the effect of reducing the temperature difference between the melting point and the freezing point may not be obtained.

In the toner wax composition of the present invention, the difference between the average carbon number of the linear saturated fatty acid constituting the compound A and the average carbon number of the linear saturated fatty acid of the compound B is 4 or less, more preferably 1 It is as follows. When the difference in average carbon number exceeds 4, the effect of reducing the temperature difference between the melting point and the freezing point may not be obtained. When the difference in average carbon number satisfies 1 or less, the effect of reducing the difference between the melting point and the freezing point becomes more remarkable.
The linear saturated fatty acid used may contain linear saturated fatty acids having different carbon numbers. In that case, the carbon number distribution of the linear saturated fatty acid used was measured and obtained. The average carbon number can be calculated from the carbon number distribution by a weighted average. The carbon number distribution of the linear saturated fatty acid used can be measured by gas chromatography.

  The wax composition for toner of the present invention can be produced by a known method. For example, a method in which the compound A and the compound B are heated and melted and uniformly mixed, and then cooled, solidified, pulverized, or granulated for production is preferable from the viewpoint of preventing variation in quality.

According to the toner wax composition of the present invention, the freezing point can be increased as compared with the case of the ester wax of Compound A alone. The freezing point of the toner wax composition of the present invention is preferably 45 to 70 ° C, more preferably 50 to 70 ° C.
The melting point of the toner wax composition of the present invention is substantially the same as that of the ester wax of Compound A. Therefore, according to the wax composition for toner of the present invention, the temperature difference between the freezing point and the melting point can be reduced as compared with the case of the compound A ester wax alone.
As described above, since the melting point of the toner wax composition of the present invention is substantially the same as the melting point of the ester wax of Compound A, the toner can be imparted with a low temperature fixability. In addition, according to the wax composition for toner of the present invention, the temperature difference between the freezing point and the melting point can be reduced as compared with the case of the ester wax of Compound A alone. It can be solidified. Accordingly, when used as a toner wax, good image quality performance can be obtained.

  The toner wax composition of the present invention is blended with a binder resin, a colorant, an external additive, a charge control agent, and the like, and a toner is produced by an ordinary production method. The compounding amount of the wax composition for toner of the present invention in the toner is usually 0.1 to 40 parts by mass with respect to 100 parts by mass of the binder resin.

  Hereinafter, the present invention will be described in more detail by showing production examples of the wax composition for toner of the present invention and evaluation methods thereof. In the following examples and comparative examples, “%” indicates parts by mass.

[Preparation of Compound A1]
Pentaerythritol 18g (0.13mol) and stearic acid 147g (0.52mol) are added to a 0.5L four-necked flask equipped with a nitrogen inlet tube, stirring blades and cooling tube, and the generated water is added under a nitrogen stream. The reaction was carried out at 220 ° C. for 10 hours while distilling off. The acid value was 6.7 mgKOH / g.
46.5 g of toluene and 32 g of 2-propanol and 19 g of a 10% aqueous potassium hydroxide solution containing potassium hydroxide equivalent to 2.0 times the acid value were added, stirred at 70 ° C. for 30 minutes, allowed to stand for 30 minutes, and then the aqueous layer. Part was removed.
Using 40 parts by mass of ion-exchanged water with respect to 100 parts by mass of the crude product, washing with water was performed 4 times at 70 ° C. to adjust the pH to 7. The solvent was distilled off from the purified product under heating and reduced pressure, and filtration, solidification, and pulverization were performed to obtain 140 g of pentaerythritol tetrastearate (Compound A1).
Table 1 shows the carbon number distribution and average carbon number (Cw) of the raw material fatty acid of Compound A1. Further, the acid value, hydroxyl value, freezing point, and melting point of the obtained compound A1 were measured as follows. The results are shown in Table 2.
The carbon number distribution of the starting fatty acid was measured by gas chromatography.

〔Measuring method〕
Carbon number distribution of raw material fatty acids: measured in accordance with JOCS (Japan Oil Chemists' Society) 2.4.2.2-2003.
Acid value: Measured according to JOCS (Japan Oil Chemists' Society) 2.3.1-1996.
Hydroxyl value: Measured according to JOCS (Japan Oil Chemists' Society) 2.3.6.2-1996.
Freezing point, melting point: “DSC-6200” manufactured by Seiko Instruments Inc. was used as a differential scanning calorimeter (DSC). The measurement is carried out by putting about 10 mg of compound A1 into a sample holder, using an empty sample holder as a reference material, raising the temperature to 150 ° C., then lowering the temperature from 150 ° C. to 30 ° C. at 10 ° C./min, 30 ° C. To 150 ° C. The temperature difference ΔT between the melting point and the freezing point was calculated from the following formula (1), with the peak top when the temperature was lowered on the obtained DSC chart as the freezing point and the peak top when the temperature was raised as the melting point. The results are shown in Table 2.
Formula (1) Melting point−Freezing point = ΔT

[Preparation of Compounds A2 to A10]
Compounds A2 to A10 were prepared according to the preparation of Compound A1 using the alcohol and linear saturated fatty acid shown in Table 1. Table 1 shows the carbon number distribution and average carbon number (Cw) of the starting fatty acid of Compound A. Further, the acid value, hydroxyl value, freezing point, melting point, and temperature difference of the obtained Compound A were measured and calculated in the same manner as Compound A1. The results are shown in Table 2.

[Preparation of Compound B1]
To a 3 L separable flask equipped with stirring blades, 257 g (0.90 mol) of stearic acid and 2500 g of water were added, and the temperature was raised to 90 ° C. Subsequently, 75 g (0.90 mol) of a 48% aqueous sodium hydroxide solution was added, and the mixture was stirred at 90 ° C. for 1 hour. Thereafter, 291 g (0.45 mol) of 25% aqueous zinc sulfate solution was added dropwise over 1 hour. After completion of dropping, the mixture was further stirred for 1 hour.
1500 g of water was added to the obtained zinc stearate slurry and cooled to 65 ° C. Thereafter, the mixture was suction filtered, washed twice with 1000 g of water, and dried at 65 ° C. for 48 hours using an air dryer to obtain zinc stearate (Compound B1).
Table 3 shows the carbon number distribution and average carbon number (Cx) of the raw material straight-chain saturated fatty acid of Compound B1.

[Preparation of compounds B2 to B7]
Compounds B2 to B7 were prepared according to the preparation of Compound B1 using the raw material linear saturated fatty acid and metal species shown in Table 3. For compound B6 and compound B7, a magnesium sulfate aqueous solution and a calcium chloride aqueous solution were used in place of the zinc sulfate aqueous solution, respectively.
Table 3 shows the carbon number distribution and average carbon number (Cx) of the raw material straight-chain saturated fatty acid of Compound B.

[Preparation and Evaluation of Wax Composition for Toner]
Example 1
190.3 g of compound A1 and 1.0 g of compound B1 were added to a 0.3 L separable flask equipped with a stirring blade and a nitrogen introduction tube, and stirred at 150 ° C. for 1 hour under a nitrogen stream. Thereafter, cooling, solidification, and pulverization were performed to obtain a toner wax composition.
The solidification point and melting point of the obtained wax composition for toner were measured by the same method as for Compound A1. Moreover, the addition effect by compound B1 was computed by following formula (2) using temperature difference (DELTA) T of melting | fusing point-freezing point of compound A1. The results are shown in Table 4.
Formula (2) (ΔT of Compound A1) − (ΔT of Example 1) = (Addition Effect)

(Examples 2 to 10, Comparative Examples 1 to 13)
Using the compound A shown in Table 1 and the compound B shown in Table 3, a wax composition for toner was obtained in the same manner as in Example 1. The freezing point and melting point of the obtained wax composition for toner were measured in the same manner as in Example 1, and the temperature difference ΔT between the melting point and the freezing point and the effect of addition by compound B were calculated. The results are shown in Table 4.
Table 4 also shows the difference (| Cx−Cw |) between the average carbon number (Cw) of the raw material fatty acid of Compound A and the average carbon number (Cx) of the raw material linear saturated fatty acid of Compound B.

  As is clear from the comparison between Table 2 and Table 4, the toner wax compositions of Examples 1 to 10 can increase the freezing point by at least about 3 ° C. by containing a predetermined amount of Compound B, and further have a melting point. -The temperature difference ΔT of the freezing point could be reduced by at least about 3 ° C, and the addition effect was excellent.

Compared to Examples 1 to 10, in Comparative Examples 1 and 2, since the mass ratio of Compound B was smaller than 0.3, the effect of addition by Compound B1 on Compound A1 was not obtained.
In Comparative Examples 3, 4, 5, and 6, the difference in average carbon number between compound A and compound B (| Cx−Cw |) exceeded 4, so the effect of addition was not obtained. In Comparative Example 7, the difference in average carbon number (| Cx−Cw |) satisfying the condition of 4 or less, but since the average carbon number (Cx) of Compound B5 is less than 14, the effect of addition was obtained. I couldn't.

In Comparative Examples 8 and 9, monoesters (A7, A8) are used, and in Comparative Example 10, tripentaerystol ester (A9) is used. These esters (A7 to A9) are pentaerythritol as shown in Table 2. Since the temperature difference ΔT between the melting point and the freezing point is smaller than that of the ester or dipentaerythritol ester, the effect of addition by the compound B was not obtained.
Moreover, since the glycerin ester (A10) was used in the comparative example 11, the addition effect by the compound B was not able to be confirmed.
In Comparative Examples 12 and 13, since the metal species of Compound B was changed to magnesium and calcium, Compound B could not be completely melt-mixed during the production of the toner wax composition, and the addition effect was not obtained. .

Claims (1)

The average of the linear saturated fatty acid which consists of a molten mixture of the compound A and the compound B shown below, the mass ratio of the compound A and the compound B is 99.7: 0.3-90: 10, and comprises the compound A A wax composition for toner, wherein the difference between the carbon number and the average carbon number of the linear saturated fatty acid of Compound B is 4 or less.
Compound A: Ester wax obtained from pentaerythritol or dipentaerythritol and monovalent linear saturated fatty acid having 14 to 24 carbon atoms Compound B: zinc salt of monovalent linear saturated fatty acid having 14 to 24 carbon atoms