阅读说明：本技术 蜡组成物及电子照像用调色剂 (Wax composition and toner for electrophotography ) 是由 小出真维 久米田淳 后藤盛之 木村雄大 于 2019-07-23 设计创作，主要内容包括：本发明所要解决的问题在于提供一种调色剂用蜡组成物,其能够对调色剂赋予低温定影性及耐热储存性,并且着色剂的分散性优异。本发明的解决手段是一种调色剂用蜡组成物,其包含：蜡a,其包含直链单羧酸与直链单醇的单酯；以及,酯b,其是由具有1个羟基且碳数为12～24的直链单羧酸及碳数为12～24的直链单羧酸所组成的混合羧酸与甘油的酯；并且,包含直链单羧酸与直链单醇的单酯的蜡a的羟基值是30以下。(The present invention addresses the problem of providing a wax composition for a toner, which can impart low-temperature fixability and heat-resistant storage properties to a toner and has excellent dispersibility of a colorant. The solution of the present invention is a wax composition for toner, comprising: a wax a comprising a monoester of a linear monocarboxylic acid and a linear monoalcohol; and ester b which is an ester of glycerol and a mixed carboxylic acid consisting of a C12-24 linear monocarboxylic acid having 1 hydroxyl group and a C12-24 linear monocarboxylic acid; the wax a containing a monoester of a linear monocarboxylic acid and a linear monool has a hydroxyl value of 30 or less.)

1. A wax composition, comprising: a wax a comprising a monoester of a linear monocarboxylic acid and a linear monoalcohol; and ester b which is an ester of glycerol and a mixed carboxylic acid consisting of a C12-24 linear monocarboxylic acid having 1 hydroxyl group and a C12-24 linear monocarboxylic acid; the wax a containing a monoester of a linear monocarboxylic acid and a linear monool has a hydroxyl value of 30 or less.

2. The wax composition according to claim 1, wherein the monoester of the linear monocarboxylic acid and the linear monoalcohol has 20 to 24 carbon atoms, and the linear monoalcohol has 22 to 38 carbon atoms.

3. The wax composition according to claim 1, which comprises, in a mass ratio of 1: 4-4: 1, the wax a, and the ester b.

4. The wax composition according to claim 1, wherein the hydroxyl value is 30 or more and the iodine value is 13 or less.

5. The wax composition according to claim 1, wherein the monoester of a linear monocarboxylic acid and a linear monool is a monoester of a saturated linear monocarboxylic acid and a saturated linear monool, and wherein the mixed carboxylic acid is a mixed carboxylic acid comprising a saturated linear monocarboxylic acid having 1 hydroxyl group and 12 to 24 carbon atoms and a saturated linear monocarboxylic acid having 12 to 24 carbon atoms.

6. The wax composition according to claim 1, wherein the wax a contains 60 wt.% or more of a linear monoester.

7. A toner for electrophotography, characterized by containing the wax composition according to any one of claims 1 to 6.

8. The toner for electrophotography according to claim 7, wherein the wax composition is added in an amount of 2 to 20 wt.%.

Technical Field

The present invention relates to a wax composition and a toner for electrophotography, the toner for electrophotography containing the wax composition.

More preferably, the present invention relates to a wax composition and a toner for electrophotography, the toner for electrophotography containing the wax composition, the wax composition being capable of imparting low-temperature fixability to a toner and being suitably used for a toner, the toner containing a colorant having excellent dispersibility.

Background

A toner used in an electrophotographic apparatus such as a printer, a facsimile machine, and a copier having these functions of an electrophotographic system contains a thermoplastic resin (binder resin) as a main component, a colorant (carbon black, magnetic powder, pigment, or the like), a charge control agent, and a wax, and further contains a fluidity imparting agent, a cleaning assistant, and a transfer assistant as needed.

The toner is softened by being heated by the fixing roller in the fixing step and is fixed to the surface of the printing medium by being pressed by the fixing roller, thereby forming an image. As the role of the wax for toner contained in the toner, there are 2 kinds, and one of them is an effect of improving the fixing property. This is the following anchoring effect: bleeding occurs at low temperatures, and adhesion to recording paper is strongly maintained at low temperatures, thereby preventing low-temperature offset. The other is the following release agent effect: the wax covers the surface of the fixing roller due to bleeding at high temperature, whereby the wax enters between the toner and the fixing roller and reduces the adhesion of the toner to the fixing roller, thereby preventing high temperature offset.

In recent years, higher performance has been required for electrophotographic apparatuses such as printers, facsimiles, and copiers, and in addition to improvement of the apparatuses, higher functionality has been required for toners used in these apparatuses. In response to this, good dispersibility of the colorant and wax of the toner has been required for high image quality. Further, it is desired that the fixing temperature is low, the offset resistance is excellent, and the fixing strength is excellent, for example, because the start-up speed is high, and the standby power is saved.

In addition, a full-color image is generally formed by dividing 4 kinds of toners of magenta (magenta), cyan (cyan), yellow (yellow), and black into a plurality of times, heating and melting the divided toners, and transferring the melted toners onto a transfer material. The toner used herein is required to have good meltability and color mixing properties during heating, and therefore, is required to have a low softening point and a low melt viscosity. Particularly, in the case of a color toner, if the concentration of the colorant is high and the dispersibility is poor, the viscosity at the time of melting becomes high and the fluidity at the time of melting becomes low, so that the releasability from the roller becomes poor and the so-called offset property is lowered. Further, the fluidity at the time of melting is lowered, and the color mixing property by melting the toner after lamination is deteriorated.

Further, since transparency is impaired if the dispersibility of the colorant or wax is poor, the dispersibility of the colorant or wax is required to be good in order to obtain a color image faithful to an original.

As a method for developing low-temperature fixability, patent document 1 discloses a method of using natural wax such as carnauba wax (carnauba wax) or rice bran wax (rice bran wax) as a release agent. When these waxes are used, low-temperature fixability can be exhibited, but the releasability is insufficient, and sufficient offset resistance may not be exhibited. Further, these natural waxes have poor dispersibility of the colorant, and high quality images cannot be obtained.

Patent document 2 describes a monoester having a specific complex viscosity (complex viscocity). Although the double viscosity monoester wax has good fixability, the monoester wax obtained is significantly colored by using sulfuric acid as a catalyst in synthesizing the monoester wax and performing the reaction at a high temperature of 240 ℃, and there may be a problem in color reproducibility or a point of colorant dispersibility in color printing.

Patent document 3 discloses a toner obtained by using a mixture of carnauba wax and nonpolar paraffin wax as a release agent.

According to this technique, if a mixture of carnauba wax and nonpolar paraffin wax is used as a release agent, and a polyol component, that is, cyclohexanedimethanol, is used as an essential component as a binder resin, and the acid value is 5 to 20mgKOH/g, it is possible to provide a color toner having good fixing property, gloss, transparency, and releasability without applying a fixing oil to a fixing device.

However, even if the acid value of the resin is increased in the above manner, the non-polar paraffin has a problem that it is difficult to ensure good dispersibility.

Thus, there is a demand for a wax composition for toner having low-temperature fixability, in which the dispersibility of the wax and the colorant is excellent. Further, a toner is required which does not aggregate even under high temperature conditions. That is, there is a need for a wax composition for toners that is capable of improving heat-resistant storage properties.

Documents of the prior art

(patent document)

Patent document 1: japanese laid-open patent publication No. 4-362953

Patent document 2: japanese patent laid-open publication No. 2013-015673

Patent document 3: japanese patent laid-open publication No. 2004-287218

Disclosure of Invention

Problems to be solved by the invention

The purpose of the present invention is to provide a wax composition for a toner, which can suitably impart heat-resistant storage properties and low-temperature fixability to the toner, is not affected by the charging properties of the resin, and has excellent dispersibility of a colorant.

The present inventors have made extensive studies to solve the above problems, and as a result, have found that a composition comprising a monoester wax a comprising a linear monocarboxylic acid and a linear monool and a specific ester b can improve the dispersibility of a colorant and can impart heat-resistant storage properties and low-temperature fixability by using the composition as a wax for a toner.

That is, the present invention includes the following schemes:

< 1 > a wax composition for toner, comprising: a wax a comprising a monoester of a linear monocarboxylic acid and a linear monoalcohol; and an ester b which is an ester of glycerol and a mixed carboxylic acid consisting of a C12-24 linear monocarboxylic acid having 1 hydroxyl group and a C12-24 linear monocarboxylic acid. Here, the hydroxyl value of the wax a containing a monoester of a linear monocarboxylic acid and a linear monool is 30 or less.

< 2 > the wax composition for toner < 1 >, wherein in the monoester of the linear monocarboxylic acid and the linear monoalcohol, the number of carbon atoms of the linear monocarboxylic acid is 20 to 24, and the number of carbon atoms of the linear monoalcohol is 22 to 38.

The wax composition for toner of < 3 > such as < 1 > or < 2 > contains, by mass, 1: 4-4: 1 wax a and ester b.

The wax composition for a toner, wherein < 4 > is any one of < 1 > to < 3 >, and wherein the hydroxyl value is 30 or more and the iodine value is 13 or less.

The wax composition for a toner according to any one of < 5 > to < 1 > - < 4 >, wherein the monoester of a linear monocarboxylic acid and a linear monoalcohol is a monoester of a saturated linear monocarboxylic acid and a saturated linear monoalcohol. Further, the mixed carboxylic acid is a mixed carboxylic acid composed of a saturated linear monocarboxylic acid having 1 hydroxyl group and 12 to 24 carbon atoms and a saturated linear monocarboxylic acid having 12 to 24 carbon atoms.

The wax composition for a toner according to any one of < 6 > to < 1 > - < 5 >, wherein the wax a contains 60 wt.% or more of a linear monoester.

< 7 > an electrophotographic toner containing the wax composition for toner described in any one of < 1 > to < 6 >.

< 8 > and < 7 > wherein the wax composition for toner is added in an amount of 2 to 20 wt.%.

Effects of the invention

By mixing the wax composition for a toner of the present invention with a toner, it is possible to impart excellent low-temperature fixability and heat-resistant storage property to the toner while having excellent dispersibility of a colorant contained in the toner.

Detailed Description

The following describes embodiments of the present invention.

The wax composition of the present invention comprises: a wax a comprising a monoester of a linear monocarboxylic acid and a linear monoalcohol; and an ester b which is an ester of glycerol and a mixed carboxylic acid consisting of a C12-24 linear monocarboxylic acid having 1 hydroxyl group and a C12-24 linear monocarboxylic acid. Hereinafter, each component will be described.

Wax a

In the present invention, the wax a containing a monoester of a linear monocarboxylic acid and a linear monool preferably has a hydroxyl value of 30 or less. The hydroxyl value of the wax a is derived not only from the hydroxyl group in the monoester but also from the free alcohol or the resin component. Therefore, if the hydroxyl value exceeds 30, the heat resistance stability is lowered, the chargeability is lowered, and thus the image may be lowered. If the hydroxyl value exceeds 30, the compatibility with the ester b is lowered, and even if the hydroxyl value of the wax composition is increased, only the wax a aggregates, and the dispersibility is lowered. Further, the monoester is preferably a linear monoester having 42 or more carbon atoms. If the carbon chain has a branched structure, the compatibility with the binder resin contained in the toner increases, and the fixing release effect decreases, so that it is necessary to use a linear monoester. Further, the wax a preferably contains a linear saturated monoester as a monoester of a linear monocarboxylic acid and a linear monoalcohol. The monoester is saturated, so that the monoester is not easily oxidized, and the heat-resistant stability is also improved. The wax a may contain a linear unsaturated monoester in place of a linear saturated monoester; alternatively, the monoester may contain a linear unsaturated monoester in addition to a linear saturated monoester.

The content of the linear monoester in the wax a is preferably 40 wt.% or more, more preferably 60 wt.% or more, and still more preferably 80 wt.% or more. The larger the content, the better the fixing releasability, and the less contamination caused by the release agent adhering to the paper discharge port. If the amount is less than 40 wt.%, the fixing releasability is poor, and there is a possibility that contamination may occur due to adhesion of the release agent to the paper discharge port. The content of the linear monoester can be measured, for example, by gas chromatography.

Examples of the linear monoester used in the present invention include: synthetic ester compounds, natural ester waxes, and the like.

The synthetic ester compound can be obtained by esterification reaction of a linear higher alcohol with a linear higher carboxylic acid or a linear higher carboxylic acid halide.

Examples of the linear higher alcohol include: stearyl alcohol, arachidyl alcohol, behenyl alcohol, lignoceryl alcohol, ceryl alcohol, octacosyl alcohol, triacontanol, and the like.

Examples of the linear higher carboxylic acid include: octadecanoic acid, eicosanoic acid, docosanoic acid, tetracosanoic acid, hexacosanoic acid, octacosanoic acid, triacontanoic acid, and the like.

Examples of the method for producing the synthetic ester compound include the following methods: first, an esterification reaction (condensation reaction) is performed using an excess of a straight-chain higher carboxylic acid for a straight-chain higher alcohol component, and the excess straight-chain higher carboxylic acid is removed by deacidification using an alkaline aqueous solution. In this reaction, a catalyst may be used as necessary. Further, since the esterification reaction is an equilibrium reaction accompanied by dehydration, it can be carried out while distilling off water in the system. The reaction can be carried out at a high temperature of the following degree: the water in the system can be distilled off, and the reaction raw materials cannot escape from the system.

The natural ester wax is obtained by separating and refining wax extracted from animals and plants.

Examples of the natural ester wax include: candelilla wax (candelilla wax), carnauba wax, rice bran wax, japan wax, Jojoba oil (Jojoba oil), beeswax (beeswax), lanolin wax (lanolin wax), montan wax (montan wax), sunflower wax, and the like. However, since the natural ester wax is a mixture of a plurality of compounds, it is used by being separated and purified as the case may be. Among them, rice bran wax and sunflower wax are preferable because they have a high content of monoesters of a saturated linear fatty acid having 20 to 24 carbon atoms and a saturated linear alcohol having 22 to 38 carbon atoms and a hydroxyl value of 30 or less. The hydroxyl value is preferably 1 to 30, more preferably 1 to 20. Further, carnauba wax contains free alcohols, resins, and the like, and has a high hydroxyl value of 35. From this viewpoint, the wax a is preferably a wax other than carnauba wax.

Method for preparing rice bran wax

The rice bran wax is obtained by refining (refining) a crude wax produced as a by-product in a step of refining rice bran oil (rice crude oil) extracted from rice bran. The crude wax contains about 55 to 65 wt.% of a wax component (ester wax), about 20 to 30 wt.% of a free fatty acid, and about 5 to 15 wt.% of triglyceride. A rice bran wax is obtained by removing a soft wax composed of free fatty acids and triglycerides from a crude wax, wherein the rice bran wax contains, as a main component, a fatty acid alcohol ester composed of a saturated linear monocarboxylic acid having 22 to 24 carbon atoms and a saturated linear monoalcohol having 24 to 38 carbon atoms. The main component means that the blending ratio of the saturated linear ester wax in the rice bran wax composition is high, and for example, the content of the saturated linear ester in 100 parts by mass of the rice bran wax composition may be 60 parts by mass or more and 99 parts by mass or less, and further may be 75 parts by mass or more and 98 parts by mass or less. Further, since rice bran wax contains a small amount of polar substances such as resins, the hydroxyl value is 30 or less. The method for removing the soft wax composed of free fatty acid and triglyceride in the crude wax is obtained by the following steps: the low melting point triglycerides and aliphatic hydrocarbons, which are free fatty acids and impurities, are removed and reduced by repeating a known rice bran wax purification method such as a method of obtaining them by recrystallization using an organic solvent, a method of promoting esterification during purification, a method of adding a polyhydric alcohol to rice bran wax to esterify them, a method of melting rice bran wax under heating and reduced pressure, and the like, or a combination of purification methods. In addition, the following purification methods can be suitably applied: the mixture of crude wax extracted from rice bran and ethanol is stirred at elevated temperature to separate the mixture into colloidal particles containing wax and an ethanol component containing soft wax, and the colloidal particles are recovered from the colloid-containing liquid.

Esters b

The ester b constituting the composition for toner of the present invention is an ester of glycerol and a mixed carboxylic acid composed of a linear monocarboxylic acid having 1 hydroxyl group and 12 to 24 carbon atoms and a linear monocarboxylic acid having 12 to 24 carbon atoms, and the preparation method thereof is not limited as long as the above requirements are satisfied. The linear monocarboxylic acid having 1 hydroxyl group and 12 to 24 carbon atoms may be a saturated linear monocarboxylic acid, or the linear monocarboxylic acid having 12 to 24 carbon atoms may be a saturated linear monocarboxylic acid. Thus, the wax composition is less susceptible to oxidation and the heat resistance stability is also improved. Further, at least a part of the linear monocarboxylic acid constituting the ester b may be unsaturated.

As the ester b, for example, an ester isolated by the following manner can be used: the oil or fat such as a naturally occurring sunflower oil is subjected to a purification treatment such as hardening, extraction, distillation, filtration, crystallization, column chromatography, or the like, alone or in combination. In addition, there are the following methods: a method of synthesizing an ester from a carboxylic acid having a single composition and glycerin as raw materials, and then blending various esters so as to have the above carboxylic acid composition; or a method of preparing a monocarboxylic acid as a raw material in advance and esterifying the monocarboxylic acid so that the synthesized ester has the above carboxylic acid composition. When the esterification is carried out, for example, the following production methods are exemplified: a synthesis method carried out by oxidation reaction; a method utilizing synthesis by a carboxylic acid and a derivative thereof, a dehydration condensation reaction by a carboxylic acid compound and an alcohol compound; a reaction by an acid halide with an alcohol compound; transesterification, and the like. In the reaction, a catalyst may be used, and as the catalyst, an acidic catalyst or a basic catalyst, for example, zinc acetate or a titanium compound, may be mentioned. The reaction is carried out in an equivalent molar ratio of the starting carboxylic acid to the starting alcohol, or by adding an excessive amount of one of them. Then, purification can be carried out by recrystallization, distillation, solvent extraction, or the like.

The linear monocarboxylic acid having 1 hydroxyl group and 12 to 24 carbon atoms is represented by the following chemical formula, and examples thereof include: hydroxytetradecanoic acid, hydroxyhexadecanoic acid, hydroxyoctadecanoic acid, hydroxyeicosanoic acid, hydroxydocosanoic acid, and the like; among them, a hydroxy octadecanoic acid having 18 carbon atoms is more preferable. The position of the hydroxyl group is not particularly limited, and 12-hydroxyoctadecanoic acid with the hydroxyl group at the 12-position is preferred.

CH₃-[CH₂]_x-CHOH-[CH₂]_y-COOH

In the above formula, x and y in the above formula are integers of 0 or more satisfying 9 ≦ x + y ≦ 21 (i.e., x + y ≦ 3).

The linear monocarboxylic acid having 12 to 24 carbon atoms can be represented by the following chemical formula, and examples thereof include: dodecanoic acid, tetradecanoic acid, hexadecanoic acid, octadecanoic acid, eicosanoic acid, docosanoic acid, tetracosanoic acid, and the like.

CH₃-[CH₂]_z-COOH

In the above formula, z in the above formula is an integer satisfying 10 ≦ z ≦ 22 (i.e., z ≦ 2).

The carboxylic acid constituting the ester b is preferably a linear saturated monocarboxylic acid having a hydroxyl group and 18 carbon atoms in an amount of 60 wt.% or more, more preferably 65 to 95 wt.%. When the linear saturated monocarboxylic acid having a hydroxyl group and a carbon number of 18 is 60 wt.% or more, the releasability of the toner is good, and the winding or low-temperature offset is less likely to occur in a printed image, which is preferable.

In the ester b, when the number of carbon atoms constituting the skeleton of the linear monocarboxylic acid having a hydroxyl group and the linear monocarboxylic acid having no hydroxyl group is 12 or more, the toner particles are less likely to be aggregated even when stored in a temperature environment of about 50 ℃; when the number of carbon atoms is 24 or less, the releasability of the toner is good, and the printed image is less likely to be entangled or to be shifted at low temperature, which is preferable. Further, a linear monocarboxylic acid having 14 to 22 carbon atoms constituting the skeleton of the linear monocarboxylic acid having a hydroxyl group and the linear monocarboxylic acid having no hydroxyl group is preferable because the effect of preventing the paper from being wound around the fixing roller and the effect of preventing the low-temperature offset in the printed image become remarkable.

The acid value of the ester b is preferably 3mgKOH/g or less, and more preferably 2 mgKOH/g. When the acid value is 3mgKOH/g or less, the stability in terms of charging property and high-temperature storage is preferable.

Wax composition

The wax composition of the present invention preferably contains a wax a comprising a monoester of a linear monocarboxylic acid and a linear monoalcohol, and an ester b of glycerin and a mixed carboxylic acid comprising a linear monocarboxylic acid having 1 hydroxyl group and 12 to 24 carbon atoms and a linear monocarboxylic acid having 12 to 24 carbon atoms, in a mass ratio of 1: 4-4: 1, more preferably 2: 3-3: 2. from the viewpoint of dispersibility and storage stability of the colorant, the content of the ester b of glycerin and a mixed carboxylic acid composed of a linear monocarboxylic acid having 1 hydroxyl group and 12 to 24 carbon atoms and a linear monocarboxylic acid having 12 to 24 carbon atoms is preferably not less than the lower limit. On the other hand, from the viewpoint of mold releasability and volatility resistance, the content of the ester b of glycerol and a mixed carboxylic acid composed of a linear monocarboxylic acid having 1 hydroxyl group and 12 to 24 carbon atoms and a linear monocarboxylic acid having 12 to 24 carbon atoms is preferably not more than the above upper limit.

Further, 1 or 2 or more kinds of wax a containing a monoester of a linear monocarboxylic acid and a linear monool may be blended with 1 or 2 or more kinds of ester b of glycerin and a mixed carboxylic acid composed of a linear monocarboxylic acid having 1 hydroxyl group and 12 to 24 carbon atoms and a linear monocarboxylic acid having 12 to 24 carbon atoms.

In this way, the wax composition obtained by mixing the wax a containing the monoester of the linear monocarboxylic acid and the linear monoalcohol and the ester b of the mixed carboxylic acid consisting of the linear monocarboxylic acid having 1 hydroxyl group and 12 to 24 carbon atoms and the linear monocarboxylic acid having 12 to 24 carbon atoms and glycerin at a certain ratio as necessary can improve the dispersibility of the wax and the colorant in the toner composition. This mechanism is considered as follows.

In the case of a wax comprising a linear monocarboxylic acid and a linear monool alone, since the polarity is low and the crystallinity is high, only the wax is aggregated and crystallized when the wax is once dissolved and then solidified, and thus the dispersibility of the wax is lowered, and defective printing may occur. On the other hand, the ester b of glycerol and a mixed carboxylic acid consisting of a linear monocarboxylic acid having 1 hydroxyl group and 12 to 24 carbon atoms and a linear monocarboxylic acid having 12 to 24 carbon atoms has a hydroxyl group with high polarity, and therefore has high affinity with the colorant and contributes to the dispersibility of the colorant in the adhesive resin, but the dispersibility of the wax is poor, and when the ester b is blended alone in the toner, although the dispersibility of the colorant is improved, the releasing failure or the storage stability may be deteriorated.

It is presumed that by combining a wax a containing a monoester of a linear monocarboxylic acid and a linear monool and an ester b of a mixed carboxylic acid consisting of a linear monocarboxylic acid having 1 hydroxyl group and having 12 to 24 carbon atoms and a linear monocarboxylic acid having 12 to 24 carbon atoms and glycerin, the crystallinity, crystallization behavior, and polarity of the wax containing a monoester of a linear monocarboxylic acid and a linear monool are changed, whereby the decrease in dispersibility due to aggregation or crystallization of the wax containing a monoester of a linear monocarboxylic acid and a linear monool alone is significantly improved, and the deterioration in mold release failure or storage stability due to the ester b of a mixed carboxylic acid consisting of a linear monocarboxylic acid having 1 hydroxyl group and having 12 to 24 carbon atoms and a linear monocarboxylic acid having 12 to 24 carbon atoms and glycerin alone can also be significantly improved, thereby improving the dispersibility of the wax and the colorant in the toner composition. Further, since the ester b has a hydroxyl group in the molecule, unlike the wax a, even if a large amount of hydroxyl groups is present, the heat resistance stability is not impaired by a free alcohol or the like. On the contrary, the hydroxyl group of the ester b contributes to the improvement of the dispersibility of the wax composition and the like.

The wax composition of the present invention is preferably: a peak top temperature of a maximum endothermic peak in an endothermic curve measured by a Differential Scanning Calorimeter (DSC) is 60 ℃ or more and 100 ℃ or less; more preferably 70 ℃ or higher and 90 ℃ or lower. When the peak top temperature of the wax composition used in the present invention is not lower than the lower limit temperature, the crystallinity in the toner is not lowered, and the storage property or the developability is not lowered, which is preferable. Further, if the temperature is not higher than the upper limit temperature, the fixing temperature of the toner is not increased, and therefore, it is preferable.

The wax composition of the present invention preferably contains a wax a comprising a monoester of a linear monocarboxylic acid and a linear monoalcohol, and an ester b of glycerol and a mixed carboxylic acid comprising a linear monocarboxylic acid having 1 hydroxyl group and 12 to 24 carbon atoms and a linear monocarboxylic acid having 12 to 24 carbon atoms, the ester b having a hydroxyl value of 30 or more and an iodine value of 13 or less.

When the hydroxyl value in the wax composition is too low, the polarity is low and the affinity for the colorant is low, so that the dispersibility of the colorant in the binder resin is reduced and defective printing may occur, and therefore, it is preferably 30mgKOH/g or more and 160mgKOH/g or less. Further, when the iodine value of the wax composition is too high, the wax alone aggregates to lower the dispersibility, and the printed image is likely to be entangled or to be shifted at low temperature, and therefore, it is preferably 13 or less. The lower limit of the iodine value is usually 0.01 mg. Further, the wax composition preferably has an acid value of 10mgKOH/g or less. If the acid value is 10mgKOH/g or more, the polarity becomes low and dispersibility may deteriorate, so the acid value is preferably 10mgKOH/g or less, and the chargeability of the toner containing the wax composition of the present invention may be further improved. The lower limit of the acid value of the wax a is usually 0.01 mgKOH/g.

Here, the iodine value of the wax composition is a value measured according to the method of japan oil chemical association (JOCS)2.3.4.1-2013, which is the "standard oil and fat analysis test method for 2003" of japan oil chemical association. Likewise, acid value can be determined according to JOCS 2.3.1-2013. The hydroxyl value of the wax composition and the wax a can be measured in accordance with JOCS 2.3.6.2-2013.

Method for producing wax composition

The wax composition of the present invention can be produced by a known method. Can be manufactured, for example, by: the wax a is produced by blending a mixed carboxylic acid consisting of a linear monocarboxylic acid having 1 hydroxyl group and 12 to 24 carbon atoms and a linear monocarboxylic acid having 12 to 24 carbon atoms with an ester b of glycerin, and further blending the following adhesive resin.

From the viewpoint of the deviation in quality, it is preferable that: a wax a comprising a monoester of a linear monocarboxylic acid and a linear monool, and an ester b of glycerol and a mixed carboxylic acid comprising a linear monocarboxylic acid having 1 hydroxyl group and 12 to 24 carbon atoms and a linear monocarboxylic acid having 12 to 24 carbon atoms are heated to a temperature higher than the melting point, and then uniformly mixed, followed by filtration, cooling, microparticulation, and the like.

The wax composition of the present invention obtained in this manner can impart low-temperature fixability to toner and can achieve high image quality by good dispersion of the colorant. Therefore, the present invention can be suitably used as a wax composition for toner.

The wax composition of the present invention can be blended with a binder resin (also referred to as a binder resin), a colorant, a charge control agent, and the like, and can be used to produce a toner by a general production method. The amount (addition amount) of the wax composition for toner of the present invention to be incorporated in the toner is usually 1 to 20 parts by mass, preferably 2 to 20 parts by mass, more preferably 8 to 20 parts by mass, and particularly preferably 12 to 20 parts by mass, based on 100 parts by mass of the entire toner. With the lower limit value within the above range, the heat-resistant storage property of the toner can be exhibited well; when the upper limit value is within the above range, the low-temperature fixing performance of the toner can be satisfactorily exhibited. The wax composition of the present invention has excellent dispersibility in a toner, and therefore, even if the amount of the wax composition is increased, the wax composition can be present in the toner without being lumped. The toner may be blended with the wax composition for toner of the present invention alone or with 2 or more kinds of the wax composition for toner. The method for confirming whether or not the toner contains the wax composition is not particularly limited, and for example, the following methods can be used: an organic solvent capable of selectively dissolving a wax component in a toner is stirred with the toner. The extract obtained by stirring was dried, and a white solid (wax) was obtained as a residue.

The extract is measured using, for example, an infrared light analyzer (fourier infrared spectrometer (FT-IR)), a differential scanning thermal analyzer (DSC), or a thermal cracking (gas chromatography mass spectrometer (GC/MS)) apparatus. By comparing the standard peaks of the hydroxyl groups of the wax and ester b, the structures of the wax a and ester b can be specified. Further, by quantitatively analyzing the peak of the higher alcohol constituting the ester of the wax a and the peak of the carboxylic acid having a hydroxyl group constituting the ester b, the mass ratio of the wax a to the ester b can be calculated.

As specific examples of the binder resin, the colorant, and the charge control agent, known materials can be suitably used as described below.

Adhesive resin

Examples of the binder resin include: polyester-based resins, styrene- (meth) acrylic copolymer resins, thermoplastic elastomers, styrene-based resins, (meth) acrylic resins, olefin-based resins (for example, α -olefin resins such as polyethylene and polypropylene), vinyl-based resins (for example, polyvinyl chloride and polyvinylidene chloride), polyamide-based resins, polyether-based resins, amine ester-based resins, epoxy-based resins, polyphenylene ether-based resins, terpene phenol resins, polylactic acid resins, hydrogenated rosins, cyclized rubbers, cycloolefin copolymer resins, and the like. These binder resins can be used alone or in combination of 2 or more. Among them, polyester resins and styrene- (meth) acrylic copolymer resins are preferred from the viewpoint of satisfying the requirements of the toner such as image quality characteristics, durability, and productivity in a well-balanced manner.

Coloring agent

The colorant may be a pigment for black, a pigment for magenta, a pigment for cyan, a pigment for yellow, or a pigment of another color. As black pigments, use may be made, alone or in mixtures: lamp black, thermal black, acetylene black, channel black, furnace black, and other carbon blacks; nigrosine (nigrosine) dyes, and the like; as pigments for magenta, they can be used alone or in combination: rose bengal (rose bengal), DuPont oil red (DuPont oil red), color index (c.i.) pigment red (pigment red)1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 39, 40, 41, 48, 49, 50, 51, 52, 53, 54, 55, 57, 58, 60, 63, 64, 68, 81, 83, 87, 88, 89, 90, 112, 114, 122, 123, 163, 202, 206, 207, 209; c.i. pigment violet 19; c.i. violet 1, 2, 10, 13, 15, 23, 29, 35, etc.; as the pigment for bluish color, there can be used either singly or as mixed: aniline blue, oil blue (Calco oil blue), ultramarine blue (ultramarine blue), methylene blue chloride, phthalocyanine blue, c.i. pigment blue 2, 3, 15, 16, 17; c.i. bromoindigo (vat blue) 6; c.i. acid blue (acid blue)45 and the like; as yellow pigments, use may be made, alone or in mixtures: chrome yellow, quinoline yellow (quinoline yellow), c.i. pigment yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 15, 16, 17, 23, 65, 73, 74, 83, 93, 97, 128, 155, 180. In particular, since color mixing is good and color reproducibility is excellent, preferred colorants for full color include c.i. pigment red 57 and 122 for magenta, c.i. pigment blue 15 for cyan, and c.i. pigment yellow 17, 93, 155, and 180 for yellow.

Charge control agent

Examples of the charge control agent having positive charge properties include: nigrosine and modified substances obtained by fatty acid metal salts and the like; quaternary ammonium salts such as tributylbenzylammonium 1-hydroxy-4-naphthalenesulfonate and tetrabutylammonium tetrafluoroborate; diorganotin oxides such as dibutyltin oxide, dioctyltin oxide and dicyclohexyltin oxide; diorganotin borates such as dibutyltin borate, dioctyltin borate and dicyclohexyltin borate; pyridinium salts, azines, triphenylmethane compounds, low molecular weight polymers having cationic functional groups, and the like. These positive charge control agents may be used alone or in combination of 2 or more. Among these positive charge control agents, nigrosine compounds and quaternary ammonium salts can be preferably used. Examples of the charge control agent having negative chargeability include: organic metal compounds such as acetylacetone metal complexes, monoazo metal complexes, naphthoic acid metal complexes or salts, and salicylic acid metal complexes or salts; chelate compounds, low-molecular-weight polymers having anionic functional groups, and the like

These negative charge control agents may be used alone or in combination of 2 or more. Among these charge control agents having negative chargeability, salicylic acid-based metal complexes and monoazo metal complexes can be preferably used. The content of the charge control agent is usually in the range of 0.1 to 5.0 parts by weight, preferably 0.5 to 3.0 parts by weight, relative to 100 parts by weight of the binder resin.

Examples

The present invention will be described in more detail below by showing examples of production of the wax composition for toner of the present invention and evaluation methods thereof.

Wax composition for toner

The toner wax compositions (C-1) to (C-5) and the comparative wax compositions were prepared according to the following formulations, and the dispersibility of the colorant in the obtained wax compositions is shown in Table 1. Further, (C-1) to (C-5) correspond to examples 1 to 5.

Wax composition for toner preparation (C-1)

480g of rice bran wax (linear monoester content: 90%) and 120g of hydrogenated castor oil (a) were collected: (b) 4: 1 to a four-necked flask equipped with a thermometer, a nitrogen gas inlet tube, a stirring blade and a cooling tube, and heated and melted at 100 ℃ under nitrogen gas, and then heated and stirred for 30 minutes so that the contents become uniform. This mixture was left to cool at room temperature to solidify it, to obtain a wax composition (C-1). The rice bran wax had a hydroxyl number of 8.

The content of the linear monoester was measured by the following method: the ratio of the peak area of the linear monoester to the total area was calculated by performing gas chromatography measurement using a gas chromatography apparatus (GC-2025 manufactured by Shimadzu scientific Co.) and a column (DB-1 HT manufactured by Agilent) under a vaporization chamber condition of 380 ℃ and heating from 150 ℃ to 370 ℃ at 5 ℃/min for 10 minutes. The following C-2 to C-4 and D-1 to D-5 were also measured by the same method.

Wax composition for toner (C-2)

Except that the rice bran wax: the mass ratio of the hydrogenated castor oil is adjusted to 1: 1 (a): (b) 1: 1, a wax composition (C-2) for toner was obtained in the same manner as in (C-1). The rice bran wax in the wax composition has a hydroxyl number of 8.

Wax composition for toner (C-3)

Except that the rice bran wax: the mass ratio of the hydrogenated castor oil is adjusted to 1: 4 (a): (b) 1: the same procedure as for (C-1) was used except that 4, to obtain a wax composition for toner (C-3). The rice bran wax in the wax composition has a hydroxyl number of 8.

Wax composition for toner (C-4)

The same procedure as in (C-2) was used to obtain the wax composition for toner (C-4) except that rice bran wax having a hydroxyl value of 25 and a linear monoester content of 78% was used as the rice bran wax.

Wax composition for comparative examples 1 to 5

The toner wax compositions (D-1 to D-5) were obtained in the same manner as in (C-1) except for the following modifications. Further, (D-1) to (D-5) correspond to comparative examples 1 to 5.

Preparation of wax composition (D-1)

(D-1) was obtained by using polyethylene WAX (Sanjing Hi-WAX 320P manufactured by Sanjing chemical Co., Ltd.) in place of the hydrogenated castor oil of (C-1). The rice bran wax in the wax composition has a hydroxyl number of 8.

Preparation of wax composition (D-2)

(D-2) is obtained by using a rice bran wax alone without using hydrogenated castor oil. The rice bran wax in the wax composition has a hydroxyl number of 8.

Preparation of wax composition (D-3)

(D-3) is obtained by substituting (C-3) hydrogenated castor oil with a monocarboxylic acid alone. The rice bran wax in the wax composition has a hydroxyl number of 8.

Preparation of wax composition (D-4)

(D-4) is obtained by using hydrogenated castor oil alone without using rice bran wax.

Preparation of wax composition (D-5)

(D-5) is obtained by using carnauba wax instead of the rice bran wax of (C-2). The hydroxyl number of the ester wax in the wax composition was 38.

Method for evaluating wax composition

The acid value, iodine value and hydroxyl value of the wax compositions (C-1) to (C-5) and (D-1) to (D-5) were evaluated by the following methods.

Acid value of wax composition: according to JOCS (Japan oil chemical society) 2.3.1-2013.

(2) Iodine number of wax composition: according to JOCS (Japan oil chemical society) 2.3.1-2013.

(3) Hydroxyl value of wax composition and wax a: according to JOCS (Japan oil chemical society) 2.3.6.2-2013.

(4) Thermal properties of wax compositions

The wax compositions (C-1) to (C-4) and (D-1) to (D-5) were evaluated for their thermal properties. For the measurement of the thermal properties of the wax composition, DSC-50 manufactured by Shimadzu corporation was used. The measurement was carried out by charging about 20mg of each of the wax compositions C-1 to C-3 and D-1 to D-3 into an aluminum sample holder, using alumina as a reference material, raising the temperature from room temperature to 120 ℃ at 5 ℃/min under a nitrogen atmosphere (200 ml/min), cooling to 0 ℃ at-5 ℃/min, raising the temperature to 120 ℃ at 5 ℃/min, and confirming the thermal characteristics at this time. The results are shown in tables 2 to 3 below.

Colorant dispersibility evaluation using wax composition

Example 1

In example 1, the wax composition of (C-1) was thoroughly mixed with a resin (polyester), a colorant (pigment red), a charge control agent (low molecular weight polymer having a cationic functional group), and the like using a mixer, and then heated and kneaded at a temperature of 130 to 140 ℃ using a biaxial melt extrusion kneading machine. The state of dispersion of the kneaded compound was evaluated. After kneading, the resultant was cooled, coarsely pulverized by a cutter pulverizer, finely pulverized by a jet mill, and classified to obtain toners of respective hues. The amount of the wax composition added (content) to the toner was set to 10 wt.%.

In addition, a cross-sectional observation was performed on a part of the kneaded mixture using an optical microscope, and dispersibility of the colorant and the release agent was evaluated. Specifically, the dispersibility of the colorant and the wax was evaluated as O when the diameter of the largest block of the colorant was measured and was less than 3 μm; if it is 3 μm or more but less than 6 μm, it is evaluated as Δ; when the thickness was 6 μm or more, the thickness was evaluated as X. The dispersibility of the releasing agent was evaluated as "O" when the diameter of the largest block of the colorant was measured and was less than 5 μm; if it is 5 μm or more but less than 10 μm, it is evaluated as Δ; when the thickness is 10 μm or more, the value is evaluated as X.

O: the colorant particles are uniformly dispersed without aggregation.

: some agglutination was confirmed.

X: agglutinated and voids were observed.

Heat resistant storage property

The aggregation degree of the toners containing the wax compositions of examples and comparative examples was measured by the following method, and the heat-resistant storage property of the toner was evaluated. Specifically, 20g of the toner was put into a plastic container having a capacity of 200mL, and was left to stand in a thermostat and humidistat ("PH-3 KT" manufactured by ESPEC corporation) set at 50 ℃ for 48 hours, and then taken out. Then, 3 kinds of sieves having a mesh size of 150 μm, a mesh size of 75 μm and a mesh size of 45 μm were sequentially mounted on a powder tester (PT-S manufactured by Hosokawa Micron Co., Ltd.). 2g of a toner for evaluation of heat-resistant storage stability was put on a sieve having a mesh of 150 μm. The toner for evaluation of heat-resistant storage stability was screened under the conditions of a rheostat scale of 2 and a time of 10 seconds. The mass of toner remaining on the sieve was measured. From the measured mass of the toner, the degree of aggregation (wt.%) of the toner was calculated according to the following formula. The toner having a degree of aggregation of less than 20 wt.% was evaluated as good in heat-resistant storage stability.

Degree of aggregation (wt.%) a + b + c

a is residual toner weight on a sieve having a mesh of 150 μm/2) × 100

b-residual toner weight on 75 μm mesh sieve/2). times.100 (3/5)

c-residual toner weight on sieve 45 μm mesh/2). times.100X (1/5)

Low temperature fixing property

The toners obtained in examples and comparative examples were measured, and the temperature of a fixing roller of a commercially available copying machine (manufactured by MINOLTA, trade name: EP-870Z) was set to 120 ℃ to fix the toner image on a transfer sheet having an unfixed image. Then, the formed fixed image was rubbed with a cotton pad, and the fixing strength was calculated according to the following formula and used as an index of low-energy fixability.

Fixing strength (image density of fixed image after friction/image density of fixed image before friction) × 100 (%)

When the fixing strength was 80% or more, 70% or more but less than 80%, 60% or more to less than 70%, and less than 60%, the low-temperature fixability was evaluated as "excellent", "Δ", "x", respectively.

Examples 2 to 5

Toners were obtained in the same manner as in example 1, except that the wax compositions of (C-2) to (C-4) were used in place of (C-1). In example 5, a styrene-acrylic copolymer was used in place of the polyester. In examples 2 to 5, dispersibility, heat-resistant storage property and low-temperature fixability were evaluated in the same manner as in example 1.

Comparative examples 1 to 5

A toner was obtained in the same manner as in example 1, except that the wax compositions of (D-1) to (D-5) were used in place of (C-1). In comparative examples 1 to 5, dispersibility, heat-resistant storage property and low-temperature fixability were evaluated in the same manner as in example 1. The evaluation results of examples 1 to 5 and comparative examples 1 to 5 are shown in Table 1.

TABLE 1

TABLE 2

TABLE 3

As shown in Table 1, the wax compositions (C-1) to (C-4) of examples 1 to 5 each had a low acid value and a high hydroxyl value, and therefore, the affinity between the highly polar hydroxyl group and the colorant was improved, and good dispersibility of the colorant was exhibited.

Tables 2 and 3 show endothermic curves of the wax compositions (C-1) to (C-4) and (D-1) to (D-5) measured by a Differential Scanning Calorimeter (DSC). The results in Table 2 show that the crystallinity of the wax is reduced, the wax exhibits good dispersibility, and the endothermic peak is in the range of 60 to 100 ℃, and thus the wax exhibits excellent low-temperature fixability. When these compositions are used as a wax for toner, the colorant can be highly dispersed in the binder resin, and can contribute to high image quality.

According to tables 1, 2 and 3, comparative examples 1 to 2 were significantly low in acid value, and further had sharp endothermic peaks, and when the wax was once dissolved and solidified, only the wax was aggregated and crystallized, resulting in low dispersibility of the wax and dispersibility of the colorant. In comparative example 3, the polarity was high and the dispersibility was good, although the hydroxyl value was low, the heat storage resistance was poor. Comparative example 4 does not contain rice bran wax and uses hydrogenated castor oil alone, so the dispersibility of the wax is deteriorated. Comparative example 5 used carnauba wax instead of rice bran wax. The carnauba wax had a low content of linear monoesters and contained a large amount of resin, and thus had poor dispersibility even when the hydroxyl value in the wax composition was similar to that of example 4.

As is clear from the results in tables 1, 2 and 3, the toner of the present invention has good dispersibility of the colorant, good low-temperature fixability, excellent heat-resistant storage property and good printing characteristics.

Industrial applicability

According to the present invention, there can be provided a wax having high dispersibility of a colorant, high transparency, high quality image characteristics, and excellent heat-resistant storage properties, and a toner obtained using the wax.