阅读说明：本技术 品红调色剂及其制造方法 (Magenta toner and method for producing same ) 是由 渡边真司 于 2019-09-13 设计创作，主要内容包括：本发明提供一种品红调色剂及其制造方法,该品红调色剂即使量少也呈现比以往更鲜明的色彩且反射密度高、低温定影性与耐热保存性的平衡优异,进而具有优异的印刷耐久性、粗大颗粒少。该品红调色剂的特征在于含有粘结树脂和品红着色剂,作为上述品红着色剂,包含用松香酸金属盐对由下述式(1)表示的颜料进行表面处理而得到的品红颜料A,上述品红颜料A的含量相对于100质量份的上述粘结树脂为1～5质量份,上述松香酸金属盐相对于100质量份的上述品红颜料A为1～7质量份。(式(1)中,Me表示二价的金属。)。(The invention provides a magenta toner which exhibits a clearer hue than conventional toners even when the amount of the toner is small, has a high reflection density, an excellent balance between low-temperature fixing properties and heat-resistant storage properties, and further has excellent printing durability and a small amount of coarse particles, and a method for producing the magenta toner. The magenta toner is characterized by containing a binder resin and a magenta colorant, and as the magenta colorant, the magenta toner contains a magenta pigment A obtained by surface-treating a pigment represented by the following formula (1) with a rosin acid metal salt, wherein the content of the magenta pigment A is 1-5 parts by mass relative to 100 parts by mass of the binder resin, and the content of the rosin acid metal salt is 1-7 parts by mass relative to 100 parts by mass of the magenta pigment A.)

1. A magenta toner comprising a binder resin and a magenta colorant,

the magenta colorant includes a magenta pigment A obtained by surface-treating a pigment represented by the following formula (1) with a rosin acid metal salt,

the content of the magenta pigment A is 1 to 5 parts by mass relative to 100 parts by mass of the binder resin,

100 parts by mass of the magenta pigment A contains 1 to 7 parts by mass of the rosin acid metal salt,

in formula (1), Me represents a divalent metal.

2. The magenta toner according to claim 1, wherein the acid value of the magenta pigment a is 2.4mg/KOH or less.

3. The magenta toner according to claim 1 or 2, further containing c.i. pigment violet 19 as the magenta colorant.

4. The magenta toner according to any one of claims 1 to 3, further comprising C.I. pigment Red 122 as the magenta colorant.

5. A method for producing the magenta toner according to any one of claims 1 to 4, comprising:

a step for preparing a polymerizable monomer composition containing a polymerizable monomer and the magenta colorant;

dispersing the polymerizable monomer composition in an aqueous medium containing a dispersion stabilizer; and

and a step of forming colored resin particles by supplying the polymerizable monomer composition to a polymerization reaction in the presence of a polymerization initiator.

Technical Field

The present invention relates to a magenta toner which exhibits a clearer hue than conventional toners even in a small amount, has a high reflection density, is excellent in balance between low-temperature fixing properties and heat-resistant storage properties, and further has excellent printing durability and contains a small amount of coarse particles, and a method for producing the magenta toner.

Background

In an image forming apparatus such as an electrophotographic apparatus, an electrostatic recording apparatus, or the like, an electrostatic latent image formed on a photoreceptor is first developed with toner. The formed toner image is transferred to a transfer material such as paper as needed, and then fixed by various means such as heating, pressurization, or solvent vapor. Among such image forming apparatuses, digital full-color copiers and digital full-color printers are put into practical use. The digital full-color copier separates color images of a color image document by blue, green, and red filters, develops an electrostatic latent image formed of 20 to 70 μm dot diameter, which includes a toner corresponding to an original color document, with yellow, magenta, cyan, and black toners, and forms a full-color image by subtractive color mixing.

In recent years, there has been an increasing demand for high image quality and high definition of the full-color image. In particular, in order to improve color reproducibility, it is desirable to be able to print with the same hue as that of printing with ink. Hitherto, quinacridone pigments, thioindigo pigments, xanthene pigments, monoazo pigments, perylene pigments, diketopyrrolopyrrole pigments, and the like have been known to be used for magenta toners.

Patent document 1 discloses a toner for electrostatic latent image development, which is characterized in that resin particles and colorant particles are fused in an aqueous medium to form a toner for electrostatic latent image development, wherein the colorant particles contain a colorant selected from at least one of pigment red 48: 1, pigment red 48: 2, pigment red 48: 3, pigment red 48: 4, and pigment red 48: 5. Patent document 1 describes the following: such a toner is a toner for developing an electrostatic latent image which does not change color at the time of thermal fixing.

Further, an example is known in which the combination of an azo lake pigment and a dye is used to improve the toner characteristics.

Patent document 2 discloses a magenta toner for color electrophotography containing a compound classified into c.i. disperse violet 31 and an azo lake pigment. Patent document 2 describes the following: by using these azo lake pigments and dyes in combination, a vivid magenta color can be obtained.

Patent document 3 discloses an electrostatic developing toner containing, as an essential component, a binder resin and an azo lake pigment treated with a polyvalent metal salt of a rosin acid, wherein the azo lake pigment is treated with a polyvalent metal salt of a rosin acid, and the azo lake pigment is treated with a polyvalent metal salt of a rosin acid having a contact angle with water in the range of 85 ° to 110 °. Patent document 3 describes the following: since the contact angle of the azo lake pigment treated with the polyvalent metal salt of rosin acid used is 85 ° to 110 °, the pigment dispersibility is improved and the transparency and the charging stability are improved as compared with the case of using the conventional azo lake pigment.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2002-31918;

patent document 2: japanese patent laid-open publication No. 63-129355;

patent document 3: japanese patent laid-open No. 2003-122055.

Disclosure of Invention

Problems to be solved by the invention

The electrophotographic image forming apparatus is used in a wide range from an apparatus used for printing and simply copying documents in offices as a general copying machine and a printer to a field of producing printed matters for use in offices, and more specifically, is used in a wide range from a field of producing printed matters for use in light printing to a field of Print On Demand (POD) because electronic data can be easily printed as Variable information. Therefore, in recent years, the level of the demand for the saturation and reflection density of printed matter has been rapidly increased.

However, the magenta toners disclosed in patent documents 1 to 3 are not at all applicable to the above-described various uses for the following various reasons.

First, patent document 1 discloses the results of experiments in which c.i. pigment red 48: 3, c.i. pigment red 48: 1, and c.i. pigment red 48: 4 were used in a suspension polymerization toner (colored particle production examples 9 to 11). However, according to the studies of the inventors, it has been found that depending on the origin and type of these pigments, when they are directly supplied to suspension polymerization, many coarse particles are generated.

Next, the dye used in the technique of patent document 2 has properties of being soluble in a solvent and generally not light-fast, unlike the pigment. Therefore, when a dye is combined with a pigment, there is sometimes a problem that light resistance is lowered.

Next, in the toner of patent document 3, c.i. pigment red 57: 1 treated by a rosin-based polyvalent metal salt is used. However, according to the studies of the inventors, it has been found that when such a pigment is supplied to suspension polymerization, a large number of coarse particles are generated.

In order to be applied to such various applications, the level of the requirement for the saturation and reflection density of printed matter has been rapidly increasing in recent years. In order to meet such a high level of demand, an object of the present invention is to provide a magenta toner which exhibits a clearer hue than conventional toners, has a high reflection density, is excellent in the balance between low-temperature fixability and heat-resistant storage stability, and further has excellent printing durability, and a method for producing the magenta toner.

Means for solving the problems

The present inventors have conducted extensive studies to achieve the above object and as a result, have found that a magenta toner having a higher reflection density and saturation than conventional ones, an excellent balance between low-temperature fixing properties and heat-resistant storage properties, excellent printing durability, and less coarse particles can be obtained by using a magenta pigment a prepared by a specific surface treatment as a magenta colorant, and have completed the present invention.

Specifically, the magenta toner of the present invention is a magenta toner containing a binder resin and a magenta colorant, and is characterized by comprising a magenta pigment A obtained by surface-treating a pigment represented by the following formula (1) with a rosin acid metal salt as the magenta colorant, wherein the content of the magenta pigment A is 1 to 5 parts by mass per 100 parts by mass of the binder resin, and the rosin acid metal salt is contained in 1 to 7 parts by mass per 100 parts by mass of the magenta pigment A.

[ chemical formula 1]

(in the formula (1), Me represents a divalent metal.)

In the present invention, the acid value of the magenta pigment A is 2.4mg/KOH or less.

In the present invention, c.i. pigment violet 19 may also be contained as the above magenta colorant.

In the present invention, c.i. pigment red 122 may also be contained as the above magenta colorant.

The manufacturing method of the present invention is a method for manufacturing the magenta toner, including: a step of preparing a polymerizable monomer composition containing a polymerizable monomer and the magenta colorant; a step of dispersing the polymerizable monomer composition in an aqueous medium containing a dispersion stabilizer; and a step of forming colored resin particles by supplying the polymerizable monomer composition to a polymerization reaction in the presence of a polymerization initiator.

Effects of the invention

As described above, according to the present invention, by using a specific amount of the surface-treated magenta pigment a, even when the toner amount is small, a magenta toner which exhibits a clearer hue than conventional toners, has a high reflection density, an excellent balance between low-temperature fixability and heat-resistant storage stability, and further has excellent printing durability and a small number of coarse particles can be provided.

Detailed Description

The magenta toner of the present invention is a magenta toner containing a binder resin and a magenta colorant, and the magenta colorant contains a magenta pigment A obtained by surface-treating a pigment represented by the following formula (1) with a rosin acid metal salt, wherein the content of the magenta pigment A is 1 to 5 parts by mass per 100 parts by mass of the binder resin, and the rosin acid metal salt is 1 to 7 parts by mass per 100 parts by mass of the magenta pigment A.

[ chemical formula 2]

(in the formula (1), Me represents a divalent metal.)

Hereinafter, the magenta toner of the present invention may be simply referred to as "toner".

Hereinafter, a method for producing colored resin particles preferably used in the present invention, colored resin particles obtained by the production method, and magenta toner of the present invention obtained by using the colored resin particles will be described in order.

1. Method for producing colored resin particles

In general, methods for producing colored resin particles are roughly classified into dry methods such as pulverization methods and wet methods such as emulsion polymerization aggregation methods, suspension polymerization methods, and dissolution suspension methods, and wet methods are preferred because toners having excellent printing characteristics such as image reproducibility can be easily obtained. In the wet process, since a toner having a particle size distribution on the order of micrometers is easily obtained, polymerization methods such as an emulsion polymerization aggregation method and a suspension polymerization method are preferable, and the suspension polymerization method is more preferable among the polymerization methods.

The emulsion polymerization aggregation method is a method of polymerizing an emulsified polymerizable monomer to obtain a resin fine particle emulsion, and aggregating the resin fine particle emulsion with a colorant dispersion liquid or the like to produce colored resin particles. The above-mentioned dissolution suspension method is a method of producing colored resin particles by forming droplets of a solution in which toner components such as a binder resin and a colorant are dissolved or dispersed in an organic solvent in an aqueous medium and removing the organic solvent, and known methods can be used for each method.

The colored resin particles used in the present invention can be produced by a wet method or a dry method, preferably a wet method, and particularly preferably a suspension polymerization method among the wet methods, and can be produced by the following process.

(A) Suspension polymerization process

(A-1) Process for producing polymerizable monomer composition

First, a polymerizable monomer, a magenta colorant, and, if necessary, other additives such as a charge control agent and a release agent are mixed to prepare a polymerizable monomer composition. The mixing in the preparation of the polymerizable monomer composition is carried out using, for example, a medium-type disperser.

The polymerizable monomer of the present invention is a monomer having a polymerizable functional group, and the polymerizable monomer is polymerized into a binder resin. As the main component of the polymerizable monomer, a monovinyl monomer is preferably used. Examples of the monovinyl monomer include styrene; styrene derivatives such as vinyltoluene and α -methylstyrene; acrylic acid and methacrylic acid; acrylic esters such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate and dimethylaminoethyl acrylate; methacrylates such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate and dimethylaminoethyl methacrylate; nitrile compounds such as acrylonitrile and methacrylonitrile; amide compounds such as acrylamide and methacrylamide; olefins such as ethylene, propylene and butylene. These monovinylic monomers can be used either individually or in combination of two or more. Among these, as the monovinyl monomer, styrene derivatives, and derivatives of acrylic acid or methacrylic acid are preferably used.

In order to improve the thermal offset and improve the storage stability, it is preferable to use a monovinyl monomer and an optional crosslinkable polymerizable monomer. The crosslinkable polymerizable monomer is a monomer having two or more polymerizable functional groups. Examples of the crosslinkable polymerizable monomer include aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene, and derivatives thereof; ester compounds in which an alcohol having two or more hydroxyl groups such as ethylene glycol dimethacrylate and diethylene glycol dimethacrylate forms ester bonds with two or more carboxylic acids; other divinyl compounds such as N, N-divinylaniline and divinyl ether; compounds having three or more vinyl groups, and the like. These crosslinkable polymerizable monomers can be used alone or in combination of two or more.

In the present invention, the crosslinkable polymerizable monomers are used in the following proportions: the amount of the monomer is usually 0.1 to 5 parts by mass, preferably 0.3 to 2 parts by mass, per 100 parts by mass of the monovinyl monomer.

The toner of the present invention contains, as a magenta colorant, a magenta pigment a obtained by surface-treating a pigment represented by the above formula (1) with a rosin acid metal salt. The magenta pigment a is obtained by surface-treating the pigment represented by the above formula (1) with a rosin acid metal salt.

The pigment represented by the above formula (1) can be classified into so-called lake pigments. The lake pigment is a pigment formed by insolubilizing a dye by reacting the dye with a metal salt. Since the lake pigment is less expensive than other pigments, there is an advantage that the manufacturing cost of the toner can be reduced by using the lake pigment. However, the conventional lake pigments containing the pigment represented by the above formula (1) have high water solubility despite the insolubilization treatment. Therefore, in the case of feeding an existing lake pigment to a polymerization reaction (for example, suspension polymerization reaction), there are the following problems: the lake pigment is eluted in an aqueous medium, or the formation of droplets containing the lake pigment becomes unstable, and the droplets are easily aggregated.

In the present invention, a pigment represented by the following formula (1) is surface-treated with a rosin acid metal salt to obtain a magenta pigment a, and by using this magenta pigment a, the above-mentioned problems of the conventional lake pigment do not occur, and therefore a magenta toner with a small number of coarse particles can be produced. The magenta toner obtained exhibits a clearer color than that of the conventional one even when the amount of the magenta toner is small, has a high reflection density, is excellent in the balance between low-temperature fixing properties and heat-resistant storage properties, and further has excellent printing durability.

AsExamples of the pigment represented by the above formula (1) include Me in the above formula (1)⁺⁺Is Ba⁺⁺C.I. pigment Red 48: 1, Me in the above formula (1)⁺⁺Is Ca⁺⁺C.I. pigment Red 48: 2, Me in the above formula (1)⁺⁺Is Sr⁺⁺C.I. pigment Red 48: 3, Me of the above formula (1)⁺⁺Is Mn⁺⁺C.I. pigment Red 48: 4, Me in the above formula (1)⁺⁺Is Mg⁺⁺C.I. pigment Red 48: 5 and Me in the above formula (1)⁺⁺Is Cd⁺⁺C.i. pigment red 48: 6, etc. Among them, Me in the above formula (1) is preferable⁺⁺Is Sr⁺⁺Pigment Red 48: 3(CAS No. 15782-05-5). That is, the magenta pigment a is preferably classified into c.i. pigment red 48: 3, and c.i. pigment red 48: 3 is a pigment obtained by surface treatment with a rosin acid metal salt.

As the magenta pigment a, commercially available products can be used, and previously synthesized magenta pigment a can also be used. Examples of commercially available magenta pigment A include those manufactured by Daido Chemical Corporation under the product name: NO.5500ST-RED (pigment classification: C.I. pigment Red 48: 3, content of rosin acid metal salt to 100 parts by mass of magenta pigment A: 5.0 parts by mass), product name manufactured by Daido Chemical Corporation: s-7014RED (pigment classification: C.I. pigment Red 48: 3, content of rosin acid metal salt to 100 parts by mass of magenta pigment A: 3.0 parts by mass), and the like.

In the case of synthesizing the magenta pigment a, for example, in the case of synthesizing a dye for the pigment (lake pigment) represented by the above formula (1), the dye obtained is subjected to laking by performing synthesis through a coupling reaction using a coupling agent component containing a rosin acid metal salt, and the magenta pigment a can be obtained. The magenta pigment a can be produced, for example, by bringing a pigment represented by the formula (1) as a raw material into contact with a rosin acid metal salt.

The rosin acid may be any one of publicly known and commonly used rosin acids, and examples thereof include rosin acid containing abietic acid as a main component, disproportionated rosin acid, partially hydrogenated rosin acid, fully hydrogenated rosin acid, maleic acid-modified rosin acid, fumaric acid-modified rosin acid, polymerized rosin acid, and the like. As the rosin acid, a low-acid-value rosin acid having an acid value of 170mg/KOH or less, preferably 100mg/KOH or less can be used. By using this low acid value abietic acid, the acid value of magenta pigment a can be reduced, and as a result, generation of coarse particles can be suppressed.

The rosin acid metal salt is a salt of rosin acid and a divalent, trivalent or tetravalent polyvalent metal, and examples thereof include a Ca salt, a Ba salt, a Sr salt, an Al salt, and a Zn salt. As the rosin acid metal salt, it preferably contains: the Sr salt of abietic acid has a high effect of improving the jettability (Brushing) in the toner production process, for example.

The content of the rosin acid metal salt is usually 1 to 7 parts by mass, preferably 2 to 6 parts by mass, and more preferably 2.5 to 5.5 parts by mass, based on 100 parts by mass of the magenta pigment a. When the amount of the rosin metal salt added is 1 to 7 parts by mass, the liberation of the rosin metal salt is suppressed, and thus the toner production is inhibited without the liberated rosin metal salt or its derivative, and thus a toner with a small number of coarse and large particles can be obtained. The content of the magenta pigment a can be determined as the total content of the pigment represented by the above formula (1) used as a raw material and the rosin acid metal salt as a surface treatment agent.

The acid value of the magenta pigment A is not particularly limited, but is usually 3mg/KOH or less, and among them, from the viewpoint of suppressing the generation of coarse particles, it is preferably 2.4mg/KOH or less, more preferably 0.1 to 2.0mg/KOH, and from the viewpoint of remarkably suppressing the generation of coarse particles, it is more preferably 0.3 to 1.0mg/KOH, and still more preferably 0.4 to 0.8 mg/KOH. The acid value of the magenta pigment a can be adjusted depending on, for example, the kind and the addition amount of the rosin acid metal salt. For example, by using the low acid value rosin acid metal salt as the rosin acid metal salt, the acid value of the magenta pigment A can be made 1.0mg/KOH or less.

The acid value in the present invention can be measured according to JIS K0070.

The content of the magenta pigment A is 1 to 5 parts by mass, preferably 1.5 to 4.5 parts by mass, and more preferably 2 to 4 parts by mass, based on 100 parts by mass of the binder resin. When the content of magenta pigment a is 1 part by mass or more, a toner exhibiting a clearer hue than ever, having a high reflection density, an excellent balance between low-temperature fixing properties and heat-resistant storage properties, and further having excellent printing durability can be obtained even with a small toner amount. When the content of the magenta pigment a is 5 parts by mass or less, the toner production is not inhibited by an excessive amount of the magenta pigment a, and therefore, a toner having a small number of coarse and large particles can be obtained.

Examples of magenta colorants that can be used in combination with magenta pigment A include C.I. pigment Red 31, C.I. pigment Red 122(CAS No.980-26-7), C.I. pigment Red 146, C.I. pigment Red 150, C.I. pigment Red 180, C.I. pigment Red 185, C.I. pigment Red 238, and C.I. pigment Violet 19(CAS No. 1047-16-1). By using these magenta colorants in combination with magenta pigment a, the printing durability can be further improved, and the generation of coarse particles can be further suppressed. Of these, the magenta colorants that can be used in combination with magenta pigment a are preferably c.i. pigment red 122 and c.i. pigment violet 19.

When magenta pigment a is used in combination with c.i. pigment red 122 as a magenta colorant, a magenta toner which exhibits a clearer hue than that of the conventional toner and has a high reflection density can be realized at a lower cost than before even when the toner amount is small.

The content of the c.i. pigment red 122 is usually 1 to 5 parts by mass, preferably 1.5 to 4.5 parts by mass, and more preferably 2 to 4 parts by mass, per 100 parts by mass of the binder resin. By setting the content of c.i. pigment red 122 to 1 to 5 parts by mass, magenta pigment a and c.i. pigment red 122 can be mixed in a well-balanced manner, and a clearer color and a higher reflection density can be obtained.

When magenta pigment a is used in combination with c.i. pigment violet 19 as a magenta colorant, a magenta toner which exhibits a clearer hue than that of the conventional toner and has a high reflection density can be realized at a lower cost than before even when the toner amount is small.

The content of the c.i. pigment violet 19 is usually 1 to 5 parts by mass, preferably 1.5 to 4.5 parts by mass, and more preferably 2 to 4 parts by mass, per 100 parts by mass of the binder resin. By setting the content of c.i. pigment violet 19 to 1 to 5 parts by mass, magenta pigment a and c.i. pigment violet 19 can be mixed in a well-balanced manner, and a clearer color and a higher reflection density can be obtained.

The magenta toner of the present invention may contain magenta pigment a, c.i. pigment red 122, and c.i. pigment violet 19 as magenta colorants.

Different raw materials may be used for c.i. pigment violet 19 and c.i. pigment red 122, respectively, and a colorant composition containing these may also be used. Examples of the colorant composition include a mixed crystal of c.i. pigment violet 19 and c.i. pigment red 122.

C.i. pigment violet 19 can be used as a mixed crystal with c.i. pigment 122 in order to improve weather resistance and image density and further suppress generation of coarse particles. That is, the magenta colorant used in the present invention may contain a mixed crystal of c.i. pigment red 122 and c.i. pigment violet 19 and magenta pigment a.

The mixed crystal of c.i. pigment violet 19 and c.i. pigment red 122 can be produced, for example, by a method described in U.S. patent No. 3160510 in which the mixed crystal components are recrystallized simultaneously from sulfuric acid or another suitable solvent, and if necessary, ground, and then treated with a solvent, or a method described in german patent application publication No. 1217333 in which a substituted diaminoterephthalic acid mixture is cyclized and then treated with a solvent.

In addition, the ratio of the c.i. pigment red 122 to the c.i. pigment violet 19 is usually 80: 20 to 20: 80, preferably 70: 30 to 30: 70, and more preferably 60: 40 to 40: 60 in terms of the mass ratio (c.i. pigment red 122: c.i. pigment violet 19).

When two or more magenta colorants are used, the total content of the magenta colorants is usually 2 to 10 parts by mass, preferably 3 to 9 parts by mass, and more preferably 4 to 8 parts by mass, per 100 parts by mass of the binder resin. By setting the total content of the magenta colorant to 2 to 10 parts by mass, the obtained toner exhibits higher reflection density and saturation, and the balance between low-temperature fixing property and heat-resistant storage property is improved, and further excellent printing durability can be obtained. Among these, the total content of the magenta colorant is preferably 7 parts by mass or less, more preferably 6 parts by mass or less, per 100 parts by mass of the binder resin, from the viewpoint of remarkably suppressing generation of coarse particles and from the viewpoint of improving low-temperature fixability.

In addition, in the case of using 2 or more kinds of magenta colorants, the ratio of magenta pigment a and another magenta pigment different from magenta pigment a is not particularly limited, and is preferably 70: 30 to 30: 70, more preferably 60: 40 to 40: 60, and further more preferably 55: 45 to 45: 55 in terms of a mass ratio (magenta pigment a: another magenta pigment) from the viewpoint of obtaining a clearer hue and a higher reflection density, suppressing generation of coarse particles, and improving printing durability and low-temperature fixability.

As other additives, a positively chargeable or negatively chargeable charge control agent can be used in order to improve the chargeability of the toner.

The charge control agent is not particularly limited as long as it is generally used as a charge control agent for toner, but in the charge control agent, a positively chargeable or negatively chargeable charge control resin is preferable because it has high compatibility with the polymerizable monomer and can impart stable chargeability (charge stability) to the toner particles, and further, from the viewpoint of obtaining a positively chargeable toner, a positively chargeable charge control resin is more preferably used.

Examples of the positively chargeable charge control agent include nigrosine dyes, quaternary ammonium salts, triaminotriphenylmethane compounds, imidazole compounds, and charge control resins such as polyamine resins, quaternary ammonium group-containing copolymers, and among these, the above-mentioned charge control resins are preferable.

Examples of the negatively chargeable charge control agent include charge control resins such as azo dyes containing metals such as Cr, Co, Al, and Fe, metal salicylate compounds, metal alkylsalicylate compounds, sulfonic acid group-containing copolymers, carboxylic acid group-containing copolymers, and among these, the above-mentioned charge control resins are preferable.

In the present invention, the charge control agent is used in an amount of usually 0.01 to 10 parts by mass, preferably 0.03 to 8 parts by mass, based on 100 parts by mass of the monovinyl monomer. When the amount of the charge control agent added is less than 0.01 part by mass, fogging may occur. On the other hand, when the amount of the electrically-controlled preparation added exceeds 10 parts by mass, printing contamination may occur.

When the polymerizable monomer is polymerized to form the binder resin, it is preferable to use a molecular weight modifier as another additive.

The molecular weight modifier is not particularly limited as long as it is generally used as a molecular weight modifier for toner, and examples thereof include mercaptans such as t-dodecyl mercaptan, n-octyl mercaptan and 2,2,4,6, 6-pentamethylheptane-4-mercaptan; thiuram disulfides such as tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, N '-dimethyl-N, N' -diphenylthiuram disulfide, and N, N '-dioctadecyl-N, N' -diisopropylthiuram disulfide. These molecular weight regulators may be used singly or in combination of two or more.

In the present invention, the molecular weight modifier is used in a proportion of usually 0.01 to 10 parts by mass, preferably 0.1 to 5 parts by mass, relative to 100 parts by mass of the monovinyl monomer.

Further, as another additive, a release agent is preferably added. By adding the release agent, the releasability of the toner from the fixing roller at the time of fixing can be improved. As the release agent, any release agent generally usable for toner can be used without particular limitation. Examples thereof include low molecular weight polyolefin waxes and modified waxes thereof; petroleum waxes such as paraffin wax; mineral waxes such as ozokerite; synthetic waxes such as Fischer-Tropsch wax; ester waxes such as dipentaerythritol ester and carnauba. From the viewpoint of obtaining a balance between the storage stability and the low-temperature fixing property of the toner, an ester wax is preferable, a synthetic ester wax obtained by esterifying an alcohol and a carboxylic acid is more preferable, and a synthetic ester wax in which the alcohol is a polyhydric alcohol and the carboxylic acid is a monocarboxylic acid is further preferable. These may be used alone or in combination of two or more.

The release agent is preferably used in an amount of 1 to 30 parts by mass, more preferably 5 to 20 parts by mass, based on 100 parts by mass of the monovinyl monomer.

(A-2) suspension step for obtaining suspension (droplet-forming step)

In the present invention, a polymerizable monomer composition containing a polymerizable monomer and a magenta colorant is dispersed in an aqueous medium containing a dispersion stabilizer, and after a polymerization initiator is added, droplet formation of the polymerizable monomer composition is performed. The method of droplet formation is not particularly limited, and is carried out using a device capable of strong stirring, such as a (inline type) emulsion disperser (trade name: mill, manufactured by ltd.), a high-speed emulsion disperser (manufactured by PRIMIX Corporation, trade name: t.k.hommizer MARK II), and the like.

Examples of the polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate; azo compounds such as 4,4' -azobis (4-cyanovaleric acid), 2,2' -azobis (2-methyl-N- (2-hydroxyethyl) propionamide), 2,2' -azobis (2-aminopropane) dihydrochloride, 2,2' -azobis (2, 4-dimethylvaleronitrile) and 2,2' -azobisisobutyronitrile; organic peroxides such as di-t-butyl peroxide, benzoyl peroxide, t-butyl peroxy-2-ethylhexanoate, t-butyl peroxy-2-ethylbutyrate, t-hexyl peroxy-2-ethylbutyrate, diisopropyl peroxydicarbonate, di-t-butyl peroxyisophthalate, and t-butyl peroxyisobutyrate. They can be used alone or in combination of two or more. Among these, organic peroxides are preferably used because residual polymerizable monomers can be reduced and printing durability is also excellent.

Among the organic peroxides, peroxyesters are preferred, and non-aromatic peroxyesters, i.e., peroxyesters having no aromatic ring, are more preferred, because they are efficient in the initiator and can also reduce the amount of residual polymerizable monomers.

As described above, the polymerization initiator may be added after the polymerizable monomer composition is dispersed in the aqueous medium and before the droplets are formed, or may be added to the polymerizable monomer composition before the polymerizable monomer composition is dispersed in the aqueous medium.

The amount of the polymerization initiator to be used for the polymerization reaction of the polymerizable monomer composition is preferably 0.1 to 20 parts by mass, more preferably 0.3 to 15 parts by mass, and particularly preferably 1 to 10 parts by mass, based on 100 parts by mass of the monovinyl monomer.

In the present invention, an aqueous medium refers to a medium containing water as a main component.

In the present invention, the aqueous medium preferably contains a dispersion stabilizer. Examples of the dispersion stabilizer include sulfates such as barium sulfate and calcium sulfate; carbonates such as barium carbonate, calcium carbonate, and magnesium carbonate; phosphates such as calcium phosphate; metal oxides such as aluminum oxide and titanium oxide; inorganic compounds such as metal hydroxides including aluminum hydroxide, magnesium hydroxide, and iron hydroxide, and water-soluble polymers such as polyvinyl alcohol, methyl cellulose, and gelatin; an anionic surfactant; a nonionic surfactant; organic compounds such as amphoteric surfactants. These dispersion stabilizers can be used singly or in combination of two or more.

Among the dispersion stabilizers, inorganic compounds are preferred, and as the aqueous medium containing the dispersion stabilizer, a colloid of a metal hydroxide which is hardly water-soluble is particularly preferred. By using an inorganic compound, particularly a colloid of a metal hydroxide which is hardly water-soluble, the particle size distribution of the colored resin particles can be narrowed, and the remaining amount of the dispersion stabilizer after washing can be reduced, so that the obtained polymerized toner can be reproduced clearly with an image, and further, the environmental stability is not deteriorated.

(A-3) polymerization step

As described in the above (a-2), after the droplets of the polymerizable monomer composition are formed, the polymerizable monomer composition is supplied to the polymerization reaction in the presence of the polymerization initiator, thereby forming colored resin particles. That is, an aqueous dispersion medium in which droplets of a polymerizable monomer composition are dispersed is heated to initiate polymerization, thereby forming an aqueous dispersion of colored resin particles containing a magenta colorant.

The polymerization temperature of the polymerizable monomer composition is preferably 50 ℃ or higher, and more preferably 60 to 95 ℃. The reaction time for the polymerization is preferably 1 to 20 hours, and more preferably 2 to 15 hours.

The colored resin particles can be used as a polymerization toner as they are or with an external additive added thereto, and are preferably used as a core layer of so-called core-shell (or, also referred to as "capsule") colored resin particles. The core-shell type colored resin particle has the following structure: the outer side of the core layer is coated with a shell layer formed of a material different from that of the core layer. The core layer formed of a material having a low softening point is coated with a material having a higher softening point than the core layer, and a balance between a reduction in the fixing temperature of the toner and prevention of aggregation during storage can be achieved.

The method for producing the core-shell type colored particles using the colored resin particles is not particularly limited, and the core-shell type colored particles can be produced by a conventionally known method. In view of production efficiency, in-situ (insitu) polymerization method and phase separation method are preferable.

The following describes a method for producing core-shell colored resin particles by in-situ polymerization.

The core-shell type colored resin particles can be obtained by adding a polymerizable monomer for forming the shell layer (polymerizable monomer for the shell) and a polymerization initiator to an aqueous medium in which the colored resin particles are dispersed, and polymerizing them.

As the shell polymerizable monomer, the same shell polymerizable monomer as the above polymerizable monomer can be used. Among them, monomers which can give a polymer having a Tg of more than 80 ℃ such as styrene, acrylonitrile and methyl methacrylate are preferably used singly or in combination.

Examples of the polymerization initiator used for polymerization of the shell polymerizable monomer include metal persulfates such as potassium persulfate and ammonium persulfate; and water-soluble polymerization initiators such as azo initiators including 2,2 '-azobis (2-methyl-N- (2-hydroxyethyl) propionamide) and 2,2' -azobis- (2-methyl-N- (1, 1-bis (hydroxymethyl) 2-hydroxyethyl) propionamide). These can be used alone or in combination of two or more. The amount of the polymerization initiator is preferably 0.1 to 30 parts by mass, and more preferably 1 to 20 parts by mass, based on 100 parts by mass of the shell polymerizable monomer.

The polymerization temperature of the shell layer is preferably 50 ℃ or higher, and more preferably 60 to 95 ℃. The reaction time for the polymerization is preferably 1 to 20 hours, and more preferably 2 to 15 hours.

(A-4) washing, filtration, dehydration and drying step

The aqueous dispersion of colored resin particles obtained by polymerization is preferably subjected to filtration, washing for removing the dispersion stabilizer, dehydration and drying as many times as necessary according to a conventional method after the polymerization is completed.

As the method of the above-mentioned washing, in the case where an inorganic compound is used as the dispersion stabilizer, it is preferable to remove the dispersion stabilizer by dissolving it in water by adding an acid or an alkali to the aqueous dispersion of the colored resin particles. When a colloid of an inorganic hydroxide that is hardly water-soluble is used as a dispersion stabilizer, it is preferable to adjust the pH of the aqueous dispersion of colored resin particles to 6.5 or less by adding an acid. As the acid to be added, inorganic acids such as sulfuric acid, hydrochloric acid, and nitric acid, and organic acids such as formic acid and acetic acid can be used, and sulfuric acid is particularly preferable because of high removal efficiency and a small load on production facilities.

The method of dehydration and filtration is not particularly limited, and various known methods can be used. Examples thereof include centrifugal filtration, vacuum filtration, and pressure filtration. The method of drying is also not particularly limited, and various methods can be applied.

(B) Crushing method

In the case of producing the colored resin particles by the pulverization method, the production can be carried out, for example, by the following process.

First, a binder resin, a magenta colorant, and other additives such as a charging control agent and a release agent added as needed are mixed using a mixer such as a ball mill, a V-type mixer, an FM mixer (trade name), a high-speed dissolver, an internal mixer, a Forberg, or the like. Subsequently, the resulting mixture is kneaded while heating using a pressure kneader, a twin-screw extruder, a roll, or the like. The obtained kneaded material is coarsely pulverized using a pulverizer such as a hammer mill, a cutter, a roll mill, or the like. Further, after the fine grinding is performed using a pulverizer such as a jet mill or a high-speed rotary pulverizer, the colored resin particles are classified into a desired particle size by a classifier such as an air classifier or an air classifier, and the colored resin particles are obtained by the grinding method.

In addition, as the binder resin used in the pulverization method, magenta colorant, and other additives such as a charge control agent and a release agent added as needed can be used those exemplified in the suspension polymerization method (a) above. In addition, similarly to the colored resin particles obtained by the suspension polymerization method (a), the colored resin particles obtained by the pulverization method can be used to produce core-shell type colored resin particles by an in-situ polymerization method or the like.

As the binder resin, in addition to the binder resin, a resin which has been conventionally widely used in toners can be used. Specific examples of the binder resin used in the pulverization method include polystyrene, styrene-butyl acrylate copolymer, polyester resin, epoxy resin, and the like.

2. Colored resin particle

The colored resin particles containing a magenta colorant can be obtained by the above-mentioned production method such as the suspension polymerization method (a) or the pulverization method (B).

The colored resin particles constituting the toner will be described below. The colored resin particles described below include both a core-shell type and a non-core-shell type.

The volume average particle diameter (Dv) of the colored resin particles is preferably 3 to 15 μm, and more preferably 4 to 12 μm. When Dv is less than 3 μm, the fluidity of the toner is reduced, the transferability is deteriorated, and the image density is reduced in some cases. When Dv exceeds 15 μm, the resolution of the image may be reduced.

The ratio (Dv/Dn) of the volume average particle diameter (Dv) to the number average particle diameter (Dn) of the colored resin particles is preferably 1.0 to 1.3, and more preferably 1.0 to 1.2. When Dv/Dn exceeds 1.3, the transferability, image density, and resolution may be reduced. The volume average particle diameter and the number average particle diameter of the colored resin particles can be measured using, for example, a particle size analyzer (product name: Multisizer, manufactured by Beckman Coulter, Inc.).

From the viewpoint of image reproducibility, the average circularity of the colored resin particles of the present invention is preferably 0.96 to 1.00, more preferably 0.97 to 1.00, and even more preferably 0.98 to 1.00.

When the average circularity of the colored resin particles is less than 0.96, the reproducibility of printed thin lines may be deteriorated.

3. Toner of the present invention

The toner of the present invention may be prepared by using the colored resin particles containing the magenta colorant as they are, and from the viewpoint of adjusting the charging property, fluidity, storage property, etc. of the toner, the colored resin particles may be mixed and stirred with an external additive to be subjected to an external addition treatment, thereby allowing the external additive to adhere to the surface of the colored resin particles to prepare a one-component toner.

In addition, the one-component toner may be further mixed and stirred with carrier particles to prepare a two-component developer.

The stirrer for performing the external addition treatment is not particularly limited as long as it is a stirring device capable of adhering the external additive to the surface of the colored resin particles, and the external addition treatment can be performed using a stirrer capable of performing mixing stirring, such as FMmixer (trade name, made by Nippon Coke & Engineering co., ltd.), Supermixer (trade name, made by yoda corporation), Qmixer (trade name, made by Nippon Coke & Engineering co., ltd.), Mechano Fusion System (trade name, made by Hosokawa Micro Group), and mechanomail (trade name, made by OKADA seiko.co., ltd.).

Examples of the external additive include inorganic fine particles such as silica, titanium oxide, alumina, zinc oxide, tin oxide, calcium carbonate, calcium phosphate, and cerium oxide; and organic fine particles such as polymethyl methacrylate resin, silicone resin, and melamine resin. Among these, inorganic fine particles are preferable, and among the inorganic fine particles, at least one kind of fine particles selected from silica and titanium oxide is preferable, and fine particles containing silica are particularly preferable.

These external additives may be used alone, and preferably two or more kinds are used in combination.

In the present invention, the external additive is used in a proportion of usually 0.05 to 6 parts by mass, preferably 0.2 to 5 parts by mass, relative to 100 parts by mass of the colored resin particles. When the amount of the external additive added is less than 0.05 parts by mass, transfer residue may occur. When the amount of the external additive added exceeds 6 parts by mass, fogging may occur.

The toner of the present invention obtained through the above steps is a magenta toner which exhibits a clearer hue than conventional toners even with a small toner amount, has a high reflection density, and is excellent in the balance between low-temperature fixability and heat-resistant storage stability by using a specific amount of the magenta pigment.

Examples

The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. Unless otherwise specified, parts and% are based on mass.

The test methods performed in the present example and comparative example are as follows.

1. Production of magenta pigment

Production example 1: production of Mixed crystals of magenta pigment

2, 5-bis- (4-methylphenylamino) terephthalic acid is cyclized in phosphoric acid to synthesize 2, 9-dimethylquinacridone (c.i. pigment red 122). The resulting phosphoric acid dispersion of 2, 9-dimethylquinacridone was separated by filtration with a filter and then washed with water. Water was added again to the washed 2, 9-dimethylquinacridone to prepare an aqueous dispersion having a solid content of 20%.

Similarly, an aqueous dispersion of quinacridone (c.i. pigment violet 19) having a solid content of 20% was prepared using 2, 5-diphenylamino terephthalic acid. To 250 parts of the aqueous dispersion of 20% by solid content quinacridone (c.i. pigment red 122) and 250 parts of the aqueous dispersion of 20% by solid content quinacridone (c.i. pigment violet 19) were added 250 parts of ethanol to prepare a pigment mixture. The mixture was transferred to a vessel equipped with a cooling tube, and the pigment was reacted for 5 hours under heating and refluxing with grinding. After the reaction, the pigment was separated from the reaction solution by filtration, washed, dried, and then pulverized to obtain a mixed crystal of magenta pigment (i.e., a mixed crystal of c.i. pigment red 122 and c.i. pigment violet 19). The mixed crystal contains the pigments in a mass ratio of c.i. pigment red 122 to c.i. pigment violet 19 of 1 to 1.

Production example 2: production of magenta pigment A2

After 20 parts of 4-chloro-6-sulfamic acid was dispersed in 300 parts of water, 22 parts of 20% hydrochloric acid was added, and further ice was added thereto, and 25.1 parts of a 30% aqueous solution of sodium nitrite was added dropwise while maintaining at 0 ℃.

To 500 parts of water was added 10.2 parts (equivalent of about 5% with respect to magenta pigment A2) of a potassium salt solution of disproportionated rosin acid (acid value: 170mg/KOH) (disproportionated rosin acid purity: 25%). An aqueous solution containing 1.82 parts of strontium chloride was added to a stirred diluted solution of a potassium salt of disproportionated rosin acid to obtain a suspension (suspension a) containing a strontium salt of disproportionated rosin acid.

20.6 parts of 2-hydroxy-3-naphthoic acid was dispersed in 380 parts of warm water at 60 ℃ and then 20.1 parts of 48% aqueous solution of caustic soda was added to obtain a coupling solution.

The coupling solution is added to the suspension A to prepare a coupling solution (coupling agent component).

After cooling the coupling solution to 0 ℃, the above diazonium salt suspension is added dropwise over 30 minutes while stirring. Stirring for 60 minutes at 0-3 ℃ to terminate the coupling reaction, thus obtaining the dye suspension.

An aqueous solution of 20.18 parts of strontium chloride dissolved in 90 parts of water was added thereto, and the mixture was stirred for 60 minutes to terminate the precipitation. After completion of the laking reaction, the mixture was stirred while being heated at 30 ℃ for 60 minutes to obtain an aqueous suspension of a strontium azo lake pigment (CI pigment Red 48: 3) which was surface-treated with a strontium salt of disproportionated rosin acid. Then, the mixture was heated to 60 ℃ and stirred for 60 minutes. After adjusting the pH to 7.6 with hydrochloric acid, the wet cake containing the pigment was separated by filtration and washed. The separated wet cake was dried to give a red magenta pigment A2 powder.

Production example 3: production of magenta pigment A3

A magenta pigment A3 was obtained in the same manner as in production example 2 except that disproportionated abietic acid (acid value: 170mg/KOH) was changed to disproportionated abietic acid (acid value: 100mg/KOH) in production example 2.

[ measurement of acid value of pigment ]

The acid values of magenta pigment A1 (product name: NO.5500ST-RED, manufactured by DAITO KASEI KOGYO CO., LTD., manufactured by LTD., product classification: C.I. pigment Red 48: 3), magenta pigment A2 obtained in the above-mentioned production example 2, magenta pigment A3 obtained in the above-mentioned production example 3, magenta pigment X (product name: NO.7510, manufactured by DAITO KASEI KOGYO CO., LTD., product classification: C.I. pigment Red 57: 1), and magenta pigment Y (pigment classification: C.I. pigment Red 48: 3, content of rosin metal salt to 100 parts of magenta pigment Y: 10.0 parts) were measured in accordance with JIS K0070.

2. Production of colored resin particles

< colored resin particles (1) >

2-1. preparation of polymerizable monomer composition for core:

73 parts of styrene and 27 parts of n-butyl acrylate, 0.15 parts of divinylbenzene, 0.4 parts of tetraethylthiuram disulfide and 4.0 parts of Magenta pigment A1(DAITO KASEI KOGYO CO., manufactured by LTD, product name: 5500ST-RED, pigment classification: C.I. pigment Red 48: 3, content of rosin metal salt (Sr salt) to 100 parts of Magenta pigment A1) and 3.0 parts of C.I. pigment Red 122(CAS No.980-26-7, manufactured by Clariant AG, trade name: ToManer genta) as Magenta colorants were wet-pulverized using a media disperser (manufactured by ASADA ion WORKS. CO., LTD., product name: PICOMILL). To the mixture obtained by wet pulverization, 1.0 part of a charge control resin (quaternary ammonium salt group-containing styrene-acrylic acid copolymer, copolymerization ratio of monomer having functional group: 8%) and 9.0 parts of an ester wax (manufactured by NOF Corporation, polyol ester) were added, mixed and dissolved to prepare a polymerizable monomer composition.

2-2. preparation of aqueous dispersion medium:

on the other hand, an aqueous solution of 14.1 parts of magnesium chloride dissolved in 280 parts of ion-exchanged water was gradually added with stirring to prepare a magnesium hydroxide colloidal dispersion, wherein 9.9 parts of sodium hydroxide was dissolved in 50 parts of ion-exchanged water.

2-3. preparation of polymerizable monomer for shell:

on the other hand, an aqueous dispersion of a shell-use polymerizable monomer was prepared by subjecting 2 parts of methyl methacrylate and 130 parts of water to a microdispersion treatment with an ultrasonic emulsifier.

2-4, a granulation procedure:

the polymerizable monomer composition was put into the magnesium hydroxide colloidal dispersion (magnesium hydroxide colloidal amount: 7.2 parts), and 4.4 parts of tert-butyl peroxy-2-ethylhexanoate as a polymerization initiator was added thereto with stirring. The dispersion liquid to which the polymerization initiator was added was dispersed at 15000rpm by an inline type emulsion dispersion machine (trade name: Milder manufactured by Pacific Machinery & Engineering Co., Ltd.) to form droplets of the polymerizable monomer composition.

2-5. suspension polymerization process:

the dispersion liquid containing the droplets of the polymerizable monomer composition was charged into a reactor, and heated to 90 ℃ to carry out polymerization reaction. After the polymerization conversion rate reached almost 100%, a solution in which 0.1 part of 2,2' -azobis [ 2-methyl-N- (2-hydroxyethyl) -propionamide ] (manufactured by FUJIFILM Wako Pure Chemical Corporation, trade name: VA-086, water-soluble initiator) as a polymerization initiator for shells was dissolved in the aqueous dispersion of the polymerizable monomer for shells was added to the reactor. Subsequently, the reaction mixture was maintained at 95 ℃ for 4 hours, and after further continuing the polymerization, the reaction was terminated by water cooling to obtain an aqueous dispersion of core-shell colored resin particles.

2-6, post-treatment process:

while stirring the aqueous dispersion of the colored resin particles, sulfuric acid was added until the pH became 6.0 or less, and after acid washing (25 ℃ C., 10 minutes), the colored resin particles separated by filtration were washed with water, and the washing water was filtered. The filtrate at this time had a conductivity of 20. mu.S/cm. The colored resin particles after the washing and filtering step are further dehydrated and dried to obtain dried colored resin particles (1).

< colored resin particles (2) >

The colored resin particles (2) were obtained in the same manner as in the method for producing the colored resin particles (1) except that the amount of magenta pigment a1 added was changed from 4.0 parts to 3.0 parts in the "preparation of the polymerizable monomer composition for core".

< colored resin particles (3) >

The same procedure as in the production method of colored resin particles (1) was carried out except that the amount of magenta pigment a1 added was changed from 4.0 parts to 3.0 parts and 3.0 parts of c.i. pigment red 122 was changed to 3.0 parts of the mixed crystal of the magenta pigment of production example 1 in the "preparation of polymerizable monomer composition for core", thereby obtaining colored resin particles (3).

< colored resin particles (4) >

The colored resin particles (4) were obtained in the same manner as the method for producing the colored resin particles (1) except that the amount of Magenta pigment A1 added was changed from 4.0 parts to 3.0 parts and the amount of C.I. pigment Red 122 was changed from 3.0 parts to 3.0 parts (CAS No.1047-16-1, product name: Ink Jet Magenta E5B02, manufactured by Clariant AG) in the "preparation of polymerizable monomer composition for core".

< colored resin particles (5) >

In the above "preparation of polymerizable monomer composition for core", colored resin particles (5) were obtained in the same manner as in the production method of colored resin particles (1) except that 4.0 parts of magenta pigment a1 was changed to 3.0 parts of c.i. pigment red 48: 3 (without surface treatment).

< colored resin particles (6) >

In the above "preparation of polymerizable monomer composition for core", the colored resin particles (6) were obtained in the same manner as in the production method of the colored resin particles (1) except that 4.0 parts of magenta pigment a1 was changed to 3.0 parts of magenta pigment X (DAITO KASEI KOGYO co., LTD, product name: 7510, pigment classification: c.i. pigment red 57: 1, content of rosin metal salt (Sr salt) relative to 100 parts of magenta pigment X: 5.0 parts).

< colored resin particles (7) >

In the above "preparation of polymerizable monomer composition for core", colored resin particles (7) were obtained in the same manner as in the production method of colored resin particles (1) except that 4.0 parts of magenta pigment a1 was changed to 3.0 parts of magenta pigment Y (pigment classification: c.i. pigment red 48: 3, content of rosin acid metal salt (Sr salt) relative to 100 parts of magenta pigment Y).

< colored resin particles (8) >

The colored resin particles (8) were obtained in the same manner as in the production method of the colored resin particles (1) except that the amount of magenta pigment a1 added was changed from 4.0 parts to 6.0 parts and c.i. pigment red 122 was not used in the "preparation of the polymerizable monomer composition for core".

< colored resin particles (9) >

Colored resin particles (9) were obtained in the same manner as in the method for producing colored resin particles (1) except that 7.0 parts of the mixed crystal of the magenta pigment of production example 1 was used instead of using any one of magenta pigment a1 and c.i. pigment red 122 in the "preparation of the polymerizable monomer composition for core".

< colored resin particles (10) >

In the above-mentioned "preparation of the polymerizable monomer composition for core", the colored resin particles (10) were obtained in the same manner as in the production method of the colored resin particles (1), except that neither magenta pigment A1 nor C.I. pigment Red 122 was used, and 3.0 parts of C.I. solvent Violet 59(CAS No.6408-72-6, manufactured by Clariant AG, trade name: Solvaperm Red Violet R) and 3.0 parts of C.I. pigment Red 146(CAS No.5280-68-2, manufactured by Clariant AG, trade name: Permanent Carmine FBB02) were used.

< colored resin particles (11) >

In the above-described method for producing colored resin particles (10), colored resin particles (11) were obtained in the same manner as in the method for producing colored resin particles (10), except that the amount of c.i. pigment red 146 added was changed from 3.0 parts to 4.0 parts.

< colored resin particles (12) >

A colored resin particle (12) was obtained in the same manner as the method for producing colored resin particles (2) except that in the method for producing colored resin particles (2), the magenta pigment a1 was changed to the magenta pigment a2 obtained in production example 2.

< colored resin particles (13) >

A colored resin particle (13) was obtained in the same manner as the method for producing colored resin particles (2) except that in the method for producing colored resin particles (2), the magenta pigment a1 was changed to the magenta pigment A3 obtained in production example 3.

< colored resin particles (14) >

In the above-described method for producing colored resin particles (13), colored resin particles (14) were obtained in the same manner as in the method for producing colored resin particles (13), except that the amount of magenta pigment a3 used was changed from 3.0 parts to 4.8 parts, and c.i. pigment red 122 was not used.

3. Production of magenta toner

The colored resin particles (1) to (14) were subjected to external addition treatment to produce magenta toners of examples 1 to 7 and comparative examples 1 to 7.

(example 1)

To 100 parts of the colored resin particles (1), 0.2 part of hydrophobized silica fine particles having an average particle diameter of 7nm, 1.0 part of hydrophobized silica fine particles having an average particle diameter of 22nm, and 1.26 parts of hydrophobized silica fine particles having an average particle diameter of 50nm were added and mixed by using a high-speed mixer (Nippon lake & Engineering Co., Ltd., trade name: FM mixer) to prepare a magenta toner of example 1.

(examples 2 to 7, comparative examples 1 to 7)

Magenta toners of examples 2 to 7 and comparative examples 1 to 7 were obtained in the same manner as in example 1, except that the colored resin particles (1) were changed to any of the colored resin particles (2) to (14) as shown in table 1 below.

4. Evaluation of magenta toner

The magenta toners of examples 1 to 7 and comparative examples 1 to 7 were evaluated for coarse powder amount, image density, saturation, minimum fixing temperature, fog under normal temperature and humidity (N/N) environment, heat resistance temperature (evaluation of storage property), printing durability (durability test), and charge amount (Blow-off charge amount) as described below.

4-1 evaluation of coarse powder amount

The evaluation of the amount of coarse powder of the toner was measured by a particle size distribution measuring instrument (product name: Multisizer, manufactured by Beckman Coulter, Inc.). The measurement using the Multisizer was performed with a pore size: 100 μm, dispersion medium: ISOTONII (trade name), concentration 10%, number of measurement particles: 100000 conditions.

The specific procedure is as follows. First, 0.2g of a toner sample was weighed out with a beaker, and an aqueous surfactant solution (manufactured by FUJIFILM Corporation, trade name: DRIWEL) was added thereto as a dispersant. Further, 2mL of a dispersion medium was added thereto to wet the toner, 10mL of the dispersion medium was added thereto, and the resultant was dispersed for 1 minute by an ultrasonic disperser, and then the particle size distribution based on the volume basis was measured by the particle size distribution measuring instrument.

The ratio (% by volume) of particles having a particle diameter of 20 μm or more was determined as the amount of the coarse powder based on the particle diameter distribution obtained by the measurement.

4-2. image Density and saturation determination

A magenta toner sample was charged on a cartridge of a developing device using a commercially available color printer of a non-magnetic one-component development system (printing speed: 20 sheets/minute), and then the toner was left as printing paper and left for one day and night in an environment of 23 ℃ and 50% RH (N/N). Then, the amount of toner (M/A) supplied to the developing roller during the full black printing was fixed to a value (0.25 to 0.32 mg/cm) shown in Table 1 below²) The dot of (4) was continuously printed at an image density of 5%. The 10 th copy sheet was printed in full black (100% image density), and the Image Density (ID) and saturation (C) were measured using a macbeth reflective image density measuring instrument^*). The Image Density (ID) is preferably 1.00 or more, and the saturation (C)^*) Preferably 66.0 or more.

4-3. minimum fixing temperature of toner

The temperature of the fixing roller was changed using a printer modified so that the temperature of the fixing roller portion of a commercially available printer of a non-magnetic one-component development system (24 printers: printing speed: 24 sheets/min) could be changed, the fixing ratios at the respective temperatures were measured, the relationship between the temperature and the fixing ratio was determined, and the lowest temperature at which the fixing ratio of 80% or more could be obtained was defined as the lowest fixing temperature.

The fixing ratio was calculated from the image density ratio before and after the rubbing test operation of the black-coated area on the test paper printed by the printer. That is, when the image density before the friction test is ID (front) and the image density after the friction test is ID (rear), the fixing ratio (%) is [ ID (rear)/ID (front) ] × 100. Here, the black area refers to an area controlled so that the developer adheres to all the dots (virtual dots that control the printer control unit) inside the area. The rubbing test operation is a series of operations in which a measuring portion for test paper is attached to a firmness testing machine with an adhesive tape, a load of 500g is applied, and rubbing is performed 5 times in a reciprocating manner with a rubbing terminal wound with cotton cloth.

4-4. fog measurement in Normal temperature and humidity (N/N) environment

A commercially available printer of a non-magnetic one-component development system was left for one day and night in a normal temperature and normal humidity (N/N) environment at a temperature of 23 ℃ and a humidity of 50% RH, and then fog was measured.

The fog assay is described below. First, the hue of paper not used for printing is measured, and the hue is set as a reference value (E)₀). Subsequently, full-white printing was performed using the toner by the same printer as the above "4-2. image density and saturation measurement", and the hue (E) at any 6 positions of the white coating was measured₁～E₆). Respectively calculate the color phases (E)₁～E₆) And a reference value (E)₀) The difference (Δ E) between them was evaluated as follows, taking the largest Δ E as the haze value of the toner. The smaller the haze value, the less haze and the better the printing. The color was measured using a spectrophotometer (product name: SpectroEye, manufactured by X-Rite Inc.).

A: delta E is less than 0.5

B: delta E is 0.5 or more and less than 1.5

F: delta E is 1.5 or more

4-5 evaluation of storage Property

After 10g of the toner was put into a 100mL polyethylene container and sealed, the container was immersed in a constant temperature water tank set at a predetermined temperature and taken out after 8 hours. The toner was transferred from the container thus taken out to a 42-mesh sieve so as to be kept from shaking as much as possible, and the toner was placed in a Powder measuring apparatus (product name: Powder tester PT-R, manufactured by Hosokawa Micro Group). The vibration amplitude of the sieve was set to 1.0mm, and after the sieve was vibrated for 30 seconds, the mass of the toner remaining on the sieve was measured and taken as the mass of the aggregated toner.

The maximum temperature at which the mass of the aggregated toner becomes 0.5g or less was set as the heat-resistant temperature.

4-6 durability test

The toner was placed in a commercial printer, and after standing for a day and night in an N/N environment, continuous printing was performed at a print density of 1%, and the print density and fog were measured for each 1000 sheets. The printing density was measured on the paper for the all black printing by a mibess type reflection image density measuring machine.

Fog was measured as follows. The full-white printing is performed, and the printer is stopped in the middle of the printing, so that the toner of the non-image portion on the photoreceptor after the development is attached to the tape. This tape was pasted on a new printing paper, and the hue was measured in the same manner as in the "fog measurement under normal temperature and humidity (N/N)" described above. An unused tape was stuck to the printing paper as a reference sample, the hue was measured in the same manner, and the haze value was obtained by calculating the color difference Δ E from the hues of the measurement sample and the reference sample.

The durability test was conducted until the number of continuous prints capable of maintaining the image quality of a gray haze value of 3 or less when performing full white printing was 15000. In the test results, >15000 (sheets) indicates that the above criteria are satisfied even if 15000 sheets are continuously printed.

4-7. blown charge amount

9.5g of a carrier (trade name: EF80B2, Mn-Mg-Sr soft ferrite, average particle diameter 80 μm, particle size distribution 50 to 100 μm) and 0.5g of a toner were weighed in a normal temperature and humidity (N/N) environment at 23 ℃ and a humidity of 50% RH, and the toner was placed in a glass container having a volume of 30mL and rotated at 150 rpm for 30 minutes to triboelectrically charge the toner. By means of a gas blowing meter (manufactured by Toshiba Chemical Corporation, trade name: TB-200) with nitrogen gas at 1kg/cm²The resultant carrier and toner particles were blown with air at a pressure of (2) to measure the blown charge amount of the toner.

The results of measurement and evaluation of the magenta toners of examples 1 to 7 and comparative examples 1 to 7 are shown in table 1 together with the respective toner compositions.

In table 1 below, "PR 48: 3" represents c.i. pigment red 48: 3, "PR 57: 1" represents c.i. pigment red 57: 1, "PR 122" represents c.i. pigment red 122, "PV 19" represents c.i. pigment violet 19, "SV 59" represents c.i. solvent violet 59, and "PR 146" represents c.i. pigment red 146. Further, in the following table 1, "surface treatment (parts)" means the content (parts) of rosin metal salt to 100 parts of the surface-treated magenta pigment a.

[ Table 1]

In table 1 above, the asterisk (#) in the evaluation results of comparative example 1 and comparative example 2 means that no colored resin particles could be obtained because no suspension polymerization reaction occurred, and no toner evaluation was performed. In table 1, the signs of the evaluation results of comparative examples 3 and 4 are shownIt means that since the amount of coarse particles was excessive, evaluation of toner other than the coarse powder amount evaluation was not performed.

5. Summary of toner evaluation

The magenta toner of comparative example 1 was a toner using both c.i. pigment red 48: 3 and c.i. pigment red 122 whose surfaces were not treated. In comparative example 1, since no suspension polymerization reaction occurred, no colored resin particles were obtained. Therefore, it is found that when the surface-untreated c.i. pigment red 48: 3 is used, the production of colored resin particles becomes difficult.

The magenta toner of comparative example 2 was a toner using magenta pigment X (surface-treated c.i. pigment red 57: 1) in combination with c.i. pigment red 122. In comparative example 2, since no suspension polymerization reaction occurred, no colored resin particles were obtained. Therefore, it is found that when c.i. pigment red 57: 1 after surface treatment is used, the production of colored resin particles becomes difficult.

The magenta toner of comparative example 3 was a toner using magenta pigment Y (c.i. pigment red 48: 3 after surface treatment and the above surface treatment amount of 10.0 parts) in combination with c.i. pigment red 122. In comparative example 3, the amount of coarse particles was too large, 10.5%. Therefore, it was found that even in the case of the c.i. pigment red 48: 3 after the surface treatment, coarse particles were generated when the surface treatment amount was 10.0 parts or more.

The magenta toner of comparative example 4 was a toner using 6.0 parts of magenta pigment a1 for 100 parts of the binder resin. In comparative example 4, the amount of coarse particles was as much as 12.3%. Therefore, even in the case of the magenta pigment a1, when the amount added was 6.0 parts by mass or more, coarse particles were generated.

The magenta toner of comparative example 5 is a toner using only a mixed crystal of c.i. pigment red 122 and c.i. pigment violet 19 as a magenta colorant. Comparative example 5 has a minimum fixing temperature as high as 150 ℃, a haze evaluation B in an N/N environment, a durability test result of as little as 8000 sheets, and an air-blown charge amount of as low as 64.4. mu.C/g. The lowest fixing temperature of comparative example 5 was the highest among the toners evaluated this time. Further, the evaluation of fog under an N/N environment of comparative example 5 is the lowest among the toners evaluated this time. Further, the result of the durability test of comparative example 5 is the least among the toners evaluated this time. Further, the blown charge amount of comparative example 5 was the smallest in this toner evaluation. Therefore, it is found that when only the mixed crystal is used, fog is likely to be generated due to insufficient charge amount of the toner, and further, printing durability and low-temperature fixing property are poor.

The magenta toners of comparative examples 6 and 7 were toners using c.i. solvent violet 59 in combination with c.i. pigment red 146 as magenta colorants. Saturation (C) of comparative examples 6 and 7^*) The temperature is as low as 60.3 or less, and the heat-resistant temperature is as low as 54 ℃ or less. Thus, it is known thatWhen c.i. solvent violet 59 and c.i. pigment red 146 are used in combination, the saturation (C)^*) Low, poor in storage stability.

In comparative example 6 and comparative example 7, the saturation (C) was higher in comparative example 7 containing 1.0 part of c.i. pigment red 146 in addition to the saturation (C)^*) Further as low as 58.5 and the heat resistant temperature as low as 53 ℃. Therefore, it is found that the higher the ratio of c.i. pigment red 146 in the combination of c.i. solvent violet 59 and c.i. pigment red 146, the higher the saturation (c.i. pigment red 146)^*) The lower the storage stability, the worse.

On the other hand, the magenta toners of examples 1 to 7 contained magenta pigment a as magenta pigment a1, magenta pigment a2 or magenta pigment A3 (all of which were surface-treated and the amount of the above surface treatment was 5.0 parts of c.i. pigment red 48: 3), and the content of this magenta pigment a was 3.0 to 4.8 parts with respect to 100 parts of the binder resin.

The toners of examples 1 to 7 were controlled to have a coarse powder content of 0.9% or less, and the toner particles had a desired particle size with a small amount of coarse particles even when c.i. pigment red 48: 3 was used. In addition, even in the toners of examples 1 to 7, the amount of supplied toner (amount M/A) was as small as 0.25 to 0.32mg/cm²In the case of (1), the image density is 1.01 or more, and the saturation (C) is^*) Also up to 64.8 or more. In addition, the toners of examples 1 to 7 had a minimum fixing temperature of 145 ℃ or less, a heat-resistant temperature of 55 ℃ or more, and excellent low-temperature fixing properties and storage properties. Further, the toners of examples 1 to 7 had an air-blown electrification amount of 70.1 μ C/g or more, exhibited sufficient electrification properties, and therefore had high fog evaluation under an N/N environment, and had excellent printing durability as a result of durability test of 13000 sheets or more.

Among them, in the magenta toners of examples 5 and 6, since the low acid value magenta pigment A having an acid value of 0.66 to 0.69mg/KOH was used, the coarse content was remarkably reduced to 0.2% or less, and even when C.I. pigment Red 48: 3 was used, the coarse particles were extremely small.

Therefore, in examples 1 to 7, magenta toner containing, as a magenta colorant, magenta pigment a obtained by surface-treating the pigment represented by formula (1) with a rosin metal salt, wherein the content of magenta pigment a is 1 to 5 parts by mass per 100 parts by mass of the binder resin, and 100 parts by mass of magenta pigment a contains 1 to 7 parts by mass of the rosin metal salt, has a small amount of coarse particles, and therefore exhibits a clearer hue than conventional ones even with a small toner amount, has a high reflection density, an excellent balance between low-temperature fixability and heat-resistant storage stability, and further has excellent printing durability.