Magenta toner for electrostatic charge image development

Abstract

To provide a magenta toner for electrostatic charge image development which has a color close to magenta of Japan color, is less affected by a temperature and humidity, and has stable charging property, and a method for manufacturing the same.SOLUTION: There are provided a magenta toner for electrostatic charge image development which contains a binder resin and a coloring agent, wherein the binder resin contains a crystalline polyester resin having ester group concentration of 6.0 mmol / g or more and 12.0 mmol / g or less, and the coloring agent contains C.I. pigment red 122 as a first magenta pigment, and C.I. pigment red 57:1 and / or C.I. pigment red 185, as a second magenta pigment; and a method for manufacturing the same.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a magenta toner for developing an electrostatic latent image used in electrophotography, electrostatic recording, electrostatic printing, etc., and a method for manufacturing the same.

Background Art

[0002] In a magenta toner containing a polyester resin as a binder resin, a magenta pigment to replace a quinacridone-based pigment has been studied (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In magenta toners, C.I. Pigment Red 269 etc. are used as magenta pigments having a color tone relatively close to the magenta color of Japan Color, but replacement is being studied from the viewpoints of safety etc. Therefore, a method of adjusting the color tone by mixing a plurality of magenta pigments has been tried, but in a magenta toner containing a crystalline polyester resin for improving low-temperature fixability, there is a problem that the chargeability is greatly affected by the environment (temperature, humidity).

[0005] The present invention relates to a magenta toner for developing an electrostatic latent image having a color tone close to the magenta color of Japan Color, having a stable chargeability with little influence from temperature and humidity, and a method for manufacturing the same.

Means for Solving the Problems

[0006] The present invention is 〔1〕 A magenta toner for electrostatic charge image development containing a binder resin and a colorant, wherein the binder resin contains a crystalline polyester resin having an ester group concentration of 6.0 mmol / g or more and 12.0 mmol / g or less, and the colorant contains C.I. Pigment Red 122 as a first magenta pigment and C.I. Pigment Red 57:1 and / or C.I. Pigment Red 185 as a second magenta pigment, a magenta toner for electrostatic charge image development, and 〔2〕 A method for producing the magenta toner for electrostatic charge image development according to 〔1〕 above, which has a step of melt-kneading a mixture containing a binder resin and a colorant using an open roll type kneader, a method for producing a magenta toner for electrostatic charge image development relates to.

Effect of the Invention

[0007] The magenta toner for electrostatic charge image development of the present invention has an excellent effect of having a color tone close to the magenta color of Japan Color, being less affected by temperature and humidity, and having stable chargeability.

Mode for Carrying Out the Invention

[0008] The magenta toner for electrostatic charge image development of the present invention (hereinafter also simply referred to as "magenta toner" or "toner") contains a crystalline polyester resin having a specific ester group concentration and a colorant using a specific magenta pigment in combination. Although the reason why a magenta toner having stable chargeability (charge stability) with less influence from temperature and humidity can be obtained by the method of the present invention is not clear, it is presumed as follows. The following mechanism is an estimation and is not limited thereto.

[0009] As a result of the earnest study by the inventors of the present case, first, the color tone is the magenta color of Japan Color (L * = 46.3, a * = 76.1, b *As a combination of magenta pigments for approaching [[ID=-2.9]], C.I. Pigment Red 122 (PR122) and C.I. Pigment Red 57:1 (PR57:1) and / or C.I. Pigment Red 185 (PR185) were selected. Japan Color refers to color samples regarding the standardization of printed matters in Japan. On the other hand, it was considered that the cause of the decrease in the charge stability of the toner containing the crystalline polyester resin was that when two or more kinds of pigments were used in combination, the dispersibility in the toner differed depending on the type of pigment. PR122, which is the base of the combination of magenta pigments, is a highly hydrophobic pigment like C.I. Pigment Red 269 (PR269), and it is easy to disperse in the toner through a highly hydrophobic crystalline polyester resin. However, since PR57:1 and PR185 used in combination with PR122 are relatively hydrophilic, there is a difference in hydrophobic components and dispersibility between them, and aggregation etc. are likely to occur in the toner. In contrast, in the present invention, by using a crystalline polyester resin with an increased ester group concentration, the affinity between the crystalline polyester resin and highly hydrophilic PR185 and PR57:1 can be increased, aggregation etc. of these pigments can be suppressed, and the dispersibility can be improved. As a result, unnecessary hydrophilic domains in the toner can be refined, and stable chargeability can be maintained regardless of the environment of high temperature and high humidity (HH) and low temperature and low humidity (LL).

[0010] In the present invention, from the viewpoint of increasing the affinity with PR185 and PR57:1 as described above, the binder resin contains a crystalline polyester resin having a specific ester group concentration.

[0011] The ester group concentration of the crystalline polyester resin is 6.0 mmol / g or more, preferably 6.1 mmol / g or more, more preferably 6.2 mmol / g or more, and 12.0 mmol / g or less, preferably 10.0 mmol / g or less, more preferably 9.0 mmol / g or less. When two or more kinds of crystalline polyester resins are used, the weighted average value of the ester group concentrations of each crystalline polyester resin is taken as the ester group concentration of the crystalline polyester resin.

[0012] In the present invention, the ester group concentration of the polyester resin is calculated from the following formula.

[0013] [Number]

[0014] [In the formula, A is the total amount of ester bonds (mol) generated when all the raw material monomers of the polyester resin have reacted, and B is the total mass (g) of the raw material monomers constituting the polyester resin. Note that the parentheses in the formula indicate the units of the respective numerical values.]

[0015] In the present invention, the crystalline polyester resin is preferably a polycondensate of an alcohol component containing an aliphatic diol and a carboxylic acid component containing an aliphatic dicarboxylic acid compound.

[0016] Examples of the aliphatic diol include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-butenediol, 1,7-heptanediol, 1,8-octanediol, neopentyl glycol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, and the like.

[0017] The aliphatic diol has 2 or more carbon atoms, and from the viewpoint of adjusting the ester group concentration, it is preferably 14 or less, more preferably 10 or less, and still more preferably 8 or less.

[0018] From the viewpoint of improving the low-temperature fixability of the toner, the aliphatic diol preferably has a hydroxyl group at the end of the carbon chain, and is more preferably an α,ω-linear alkanediol.

[0019] The content of the aliphatic diol is preferably 80 mol% or more, more preferably 90 mol% or more, still more preferably 95 mol% or more, and 100 mol% or less in the alcohol component.

[0020] Examples of the alcohol component other than the aliphatic diol include alkylene oxide adducts of bisphenol A, aromatic diols such as bisphenol A, hydrogenated bisphenol A, sorbitol, pentaerythritol, glycerin, and polyhydric alcohols having 3 or more valences such as trimethylolpropane.

[0021] Examples of the aliphatic dicarboxylic acid-based compound include succinic acid (carbon number: 4), fumaric acid (carbon number: 4), adipic acid (carbon number: 6), suberic acid (carbon number: 8), azelaic acid (carbon number: 9), sebacic acid (carbon number: 10), dodecanedioic acid (carbon number: 12), tetradecanedioic acid (carbon number: 14), anhydrides of these acids, and alkyl esters of these acids having 1 to 3 carbon atoms in the alkyl group. Here, when the aliphatic dicarboxylic acid-based compound is an alkyl ester, the carbon number of the alkyl group is not included in the above carbon number.

[0022] The carbon number of the aliphatic dicarboxylic acid-based compound is preferably 4 or more, more preferably 6 or more, still more preferably 8 or more, and preferably 14 or less from the viewpoint of adjusting the ester group concentration.

[0023] The content of the aliphatic dicarboxylic acid-based compound is preferably 50 mol% or more, more preferably 60 mol% or more, still more preferably 70 mol% or more, still more preferably 80 mol% or more, and 100 mol% or less in the carboxylic acid component from the viewpoint of hydrophobicity.

[0024] Examples of the other carboxylic acid components include aromatic dicarboxylic acid-based compounds such as phthalic acid, isophthalic acid, and terephthalic acid, and polyvalent carboxylic acid-based compounds having 3 or more valences such as trimellitic acid and pyromellitic acid.

[0025] Furthermore, from the perspective of durability, it is preferable that the alcohol component and / or carboxylic acid component of the crystalline polyester resin contain a monofunctional monomer.

[0026] Examples of the monofunctional monomer contained in the alcohol component include aliphatic monoalcohols such as capryl alcohol, lauryl alcohol, myristyl alcohol, palmityl alcohol, stearyl alcohol, and behenyl alcohol.

[0027] From the perspective of hydrophobicity, the number of carbon atoms of the aliphatic monoalcohol is preferably 10 or more, more preferably 12 or more, still more preferably 14 or more, and from the perspective of low-temperature fixability, it is preferably 22 or less, more preferably 20 or less, still more preferably 18 or less.

[0028] Examples of the monofunctional monomer contained in the carboxylic acid component include aliphatic monocarboxylic acids such as capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, and behenic acid, and aliphatic monocarboxylic acid-based compounds such as alkyl esters in which the number of carbon atoms of the alkyl group of these acids is 1 or more and 3 or less.

[0029] From the perspective of hydrophobicity, the number of carbon atoms of the aliphatic monocarboxylic acid-based compound is preferably 10 or more, more preferably 12 or more, still more preferably 14 or more, and from the perspective of low-temperature fixability, it is preferably 22 or less, more preferably 20 or less, still more preferably 18 or less. Here, when the aliphatic monocarboxylic acid-based compound is an alkyl ester, the number of carbon atoms of the alkyl group is not included in the above number of carbon atoms.

[0030] The content of the monofunctional monomer is preferably 1 mol% or more, more preferably 3 mol% or more, still more preferably 5 mol% or more in the total amount of the alcohol component and the carboxylic acid component, and from the perspective of low-temperature fixability, it is preferably 30 mol% or less, more preferably 20 mol% or less, still more preferably 15 mol% or less.

[0031] In this specification, macromonomers and hydroxycarboxylic acids are not included in the alcohol component and the carboxylic acid component.

[0032] The equivalent ratio of the carboxy group of the carboxylic acid component to the hydroxyl group of the alcohol component (COOH group / OH group) is preferably 0.8 or more, more preferably 0.9 or more, from the viewpoint of charge stability, and preferably 1.2 or less, more preferably 1.1 or less, from the viewpoint of low-temperature fixability.

[0033] The crystalline polyester resin can be produced, for example, by polycondensing an alcohol component and a carboxylic acid component in an inert gas atmosphere, preferably in the presence of an esterification catalyst, and further, if necessary, in the presence of a cocatalyst, a polymerization inhibitor, etc., preferably at a temperature of 120°C or higher, more preferably 180°C or higher, and preferably 230°C or lower, more preferably 220°C or lower.

[0034] Examples of the esterification catalyst include tin compounds such as dibutyltin oxide and tin(II) 2-ethylhexanoate, and titanium compounds such as titanium diisopropoxybis(triethanolaminato). The amount of the esterification catalyst used is preferably 0.01 part by mass or more, more preferably 0.05 part by mass or more, and preferably 1.5 parts by mass or less, more preferably 1 part by mass or less, based on 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component. Examples of the cocatalyst for the esterification catalyst include gallic acid. The amount of the cocatalyst used is preferably 0.001 part by mass or more, more preferably 0.01 part by mass or more, and preferably 0.5 part by mass or less, more preferably 0.1 part by mass or less, based on 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component. Examples of the polymerization inhibitor include tert-butylcatechol. The amount of the polymerization inhibitor used is preferably 0.001 part by mass or more, more preferably 0.01 part by mass or more, and preferably 0.5 part by mass or less, more preferably 0.1 part by mass or less, based on 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component.

[0035] In the present invention, the polyester resin may be a polyester resin modified to such an extent that its properties are not substantially impaired. Examples of the modified polyester resin include polyester resins grafted or blocked with phenol, urethane, epoxy, etc. by the methods described in JP-A-11-133668, JP-A-10-239903, JP-A-8-20636, etc. Among the modified polyester resins, a urethane-modified polyester resin obtained by extending a polyester resin with a polyisocyanate compound is preferred.

[0036] From the viewpoint of durability, the softening point of the crystalline polyester resin is preferably 50°C or higher, more preferably 60°C or higher, still more preferably 65°C or higher, and from the viewpoint of low-temperature fixability, it is preferably 140°C or lower, more preferably 120°C or lower, still more preferably 100°C or lower.

[0037] The crystallinity of the resin is represented by a crystallinity index defined as the ratio of the softening point to the maximum peak temperature of endotherm measured by a differential scanning calorimeter, i.e., the value of [softening point / maximum peak temperature of endotherm]. The crystalline resin has a crystallinity index of 0.6 or higher, preferably 0.7 or higher, more preferably 0.9 or higher, and is a resin of 1.4 or lower, preferably 1.2 or lower, more preferably 1.1 or lower. On the other hand, the amorphous resin is a resin in which no endothermic peak is observed, or if an endothermic peak is observed, the crystallinity index exceeds 1.4, preferably exceeds 1.5, more preferably is 1.6 or higher, or is a resin of less than 0.6, preferably 0.5 or lower. The crystallinity of the resin can be adjusted by the type and ratio of the raw material monomers, and production conditions (e.g., reaction temperature, reaction time, cooling rate), etc. The maximum peak temperature of endotherm refers to the temperature of the peak with the largest peak area among the observed endothermic peaks. In the case of a crystalline resin, the maximum peak temperature of endotherm is taken as the melting point.

[0038] From the perspective of durability, the melting point of the crystalline polyester resin is preferably 50 °C or higher, more preferably 60 °C or higher, still more preferably 65 °C or higher, and from the perspective of low-temperature fixability, it is preferably 130 °C or lower, more preferably 120 °C or lower, still more preferably 100 °C or lower.

[0039] From the perspective of low-temperature fixability, the acid value of the crystalline polyester resin is preferably 1 mgKOH / g or higher, more preferably 3 mgKOH / g or higher, and from the perspective of durability, it is preferably 20 mgKOH / g or lower, more preferably 15 mgKOH / g or lower.

[0040] From the perspective of low-temperature fixability, the content of the crystalline polyester resin in the binder resin is preferably 5% by mass or higher, more preferably 10% by mass or higher, still more preferably 15% by mass or higher, and from the perspective of durability, it is preferably 35% by mass or lower, more preferably 30% by mass or lower, still more preferably 25% by mass or lower.

[0041] From the perspective of charge stability, the binder resin preferably further contains an amorphous polyester resin.

[0042] As the amorphous polyester resin, an amorphous polyester resin or an amorphous composite resin in which a polyester resin and a styrene resin are bonded is preferable.

[0043] As the amorphous polyester resin, a polycondensate of an alcohol component containing an alkylene oxide adduct of bisphenol A and a carboxylic acid component is preferable.

[0044] As the alkylene oxide adduct of bisphenol A, the formula (I):

[0045]

Chemical formula

[0046] (In the formula, OR and RO are oxyalkylene groups, R is an ethylene group and / or a propylene group, x and y represent the average number of moles of alkylene oxide added, and are positive numbers respectively. The value of the sum of x and y is 1 or more, preferably 1.5 or more, and 16 or less, preferably 8 or less, more preferably 6 or less, and even more preferably 4 or less.) The compound represented by is preferred.

[0047] From the viewpoint of low-temperature fixing property, the content of the alkylene oxide adduct of bisphenol A is preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, and even more preferably 100 mol% in the alcohol component.

[0048] Examples of other alcohol components include aliphatic diols, bisphenol A, hydrogenated bisphenol A, sorbitol, pentaerythritol, glycerin, and polyhydric alcohols such as trimethylolpropane having 3 or more valences.

[0049] Examples of the carboxylic acid component include aromatic dicarboxylic acid compounds, aliphatic dicarboxylic acid compounds, and polyhydric carboxylic acid compounds having 3 or more valences.

[0050] Examples of the aromatic dicarboxylic acid compounds include phthalic acid, isophthalic acid, terephthalic acid, anhydrides of these acids, and alkyl esters of these acids having 1 to 3 carbon atoms.

[0051] Examples of the aliphatic dicarboxylic acid compounds include fumaric acid, maleic acid, succinic acid, succinic acid derivatives substituted with hydrocarbon groups, glutaric acid, adipic acid, sebacic acid, anhydrides of these acids, and alkyl esters of these acids having 1 to 3 carbon atoms.

[0052] Examples of the polyhydric carboxylic acid compounds having 3 or more valences include trimellitic acid, pyromellitic acid, anhydrides of these acids, and alkyl esters of these acids having 1 to 3 carbon atoms.

[0053] In addition, the alcohol component may appropriately contain a monohydric alcohol, and the carboxylic acid component may appropriately contain a monohydric carboxylic acid compound.

[0054] The equivalent ratio of the carboxyl group of the carboxylic acid component to the hydroxyl group of the alcohol component (COOH group / OH group) is preferably 0.6 or more, more preferably 0.7 or more, still more preferably 0.8 or more, and preferably 1.3 or less, more preferably 1.2 or less, from the viewpoint of adjusting the softening point of the polyester resin.

[0055] The polycondensation reaction conditions of the alcohol component and the carboxylic acid component of the amorphous polyester resin are the same as those of the crystalline polyester resin, except that a suitable reaction temperature is 160°C or higher, more preferably 180°C or higher, and 250°C or lower, more preferably 240°C or lower.

[0056] The polyester resin in the composite resin is the same as the amorphous polyester resin described above. The styrene resin is an addition polymer of a raw material monomer containing at least styrene or a styrene derivative such as α-methylstyrene or vinyltoluene (hereinafter, styrene and styrene derivatives are collectively referred to as "styrene compounds").

[0057] The content of the styrene compound, preferably styrene, in the raw material monomer of the styrene resin is preferably 50% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, from the viewpoint of storage stability, and preferably 95% by mass or less, more preferably 93% by mass or less, still more preferably 90% by mass or less, from the viewpoint of low-temperature fixability.

[0058] In addition, the styrene resin may contain an alkyl (meth)acrylate having 7 or more carbon atoms in the alkyl group as a raw material monomer. Examples of the alkyl (meth)acrylate include 2-ethylhexyl (meth)acrylate, (iso)octyl (meth)acrylate, (iso)decyl (meth)acrylate, (iso)stearyl (meth)acrylate, and the like. It is preferable to use one or more of these. In the present specification, “(iso)” means including both the case where this group is present and the case where it is not, and when these groups are not present, it indicates normal. Further, “(meth)acrylic acid” means acrylic acid, methacrylic acid, or both of them.

[0059] The number of carbon atoms in the alkyl group of the alkyl (meth)acrylate as a raw material monomer of the styrene resin is preferably 7 or more, more preferably 8 or more, and preferably 12 or less, more preferably 10 or less, from the viewpoint of improving the low-temperature fixability of the toner. Note that the number of carbon atoms of the alkyl ester refers to the number of carbon atoms derived from the alcohol component constituting the ester.

[0060] The raw material monomers of the styrene resin may include raw material monomers other than styrene compounds and alkyl (meth)acrylates, for example, ethylenically unsaturated monoolefins such as ethylene and propylene; diolefins such as butadiene; halovinyls such as vinyl chloride; vinyl esters such as vinyl acetate and vinyl propionate; ethylenically monocarboxylic acid esters such as dimethylaminoethyl (meth)acrylate; vinyl ethers such as methyl vinyl ether; vinylidene halides such as vinylidene chloride; N-vinyl compounds such as N-vinylpyrrolidone, and the like.

[0061] The addition polymerization reaction of the raw material monomers of the styrene resin can be carried out by a conventional method in the presence of a polymerization initiator such as dibutyl peroxide and dicumyl peroxide, a chain transfer agent, a crosslinking agent, etc., in the presence of an organic solvent or without a solvent. As the temperature condition, it is preferably 110 °C or higher, more preferably 140 °C or higher, and preferably 200 °C or lower.

[0062] When using an organic solvent during the addition polymerization reaction, xylene, toluene, methyl ethyl ketone, acetone, etc. can be used. The amount of the organic solvent used is preferably 10 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the raw material monomers of the styrene resin.

[0063] The composite resin is preferably a resin in which a polyester resin and a styrene resin are bonded, and more preferably a resin in which the polyester resin and the styrene resin are chemically bonded through a bifunctional monomer capable of reacting with both the raw material monomers of the polyester resin and the raw material monomers of the styrene resin.

[0064] The bifunctional monomer preferably has at least one functional group selected from the group consisting of a hydroxyl group, a carboxyl group, an epoxy group, a primary amino group and a secondary amino group in the molecule, preferably a hydroxyl group and / or a carboxyl group, more preferably a carboxyl group, and an ethylenically unsaturated bond. A compound having them is preferred, and at least one selected from the group consisting of acrylic acid, methacrylic acid, fumaric acid, maleic acid and maleic anhydride is more preferred. From the viewpoint of the reactivity of the polycondensation reaction and the addition polymerization reaction, at least one selected from the group consisting of acrylic acid, methacrylic acid and fumaric acid is even more preferred. However, when used together with a polymerization inhibitor, a polycarboxylic acid-based compound having an ethylenically unsaturated bond such as fumaric acid functions as a raw material monomer of the polyester resin. In this case, fumaric acid, etc. are not bifunctional monomers but raw material monomers of the polyester resin.

[0065] The amount of the bifunctional monomer used is preferably 1 mol or more, more preferably 2 mol or more, based on 100 mol in total of the alcohol components of the polyester resin, from the viewpoint of enhancing the dispersibility between the styrene resin and the polyester resin and improving the dispersibility of the raw materials in the toner. And from the viewpoint of improving the low-temperature fixability of the toner, it is preferably 30 mol or less, more preferably 20 mol or less, still more preferably 10 mol or less.

[0066] Specifically, it is preferable to produce the composite resin by the following method. When using a bifunctional monomer, the bifunctional monomer is preferably used together with the raw material monomers of the polyester resin from the viewpoint of improving the dispersibility of the pigment and the crystalline polyester resin in the toner.

[0067] (i) A method in which after the step (A) of polycondensation reaction with the raw material monomers of the polyester resin, the step (B) of addition polymerization reaction with the raw material monomers of the styrene resin is carried out In this method, step (A) is carried out under temperature conditions suitable for the polycondensation reaction, the temperature is lowered, and step (B) is carried out under temperature conditions suitable for the addition polymerization reaction. The raw material monomers of the styrene resin are preferably added into the reaction system at a temperature suitable for the addition polymerization reaction. After step (B), the temperature is raised again, and if necessary, raw material monomers of a polyester resin with a trivalent or higher valence that serves as a crosslinking agent are added to the polymerization system, and the polycondensation reaction in step (A) and the reaction with the bifunctional monomer can be further advanced.

[0068] (ii) A method in which after the step (B) of addition polymerization reaction with the raw material monomers of the styrene resin, the step (A) of polycondensation reaction with the raw material monomers of the polyester resin is carried out In this method, step (B) is carried out under temperature conditions suitable for the addition polymerization reaction, the temperature is raised, and the polycondensation reaction in step (A) is carried out under temperature conditions suitable for the polycondensation reaction. The raw material monomers of the polyester resin may be present in the reaction system during the addition polymerization reaction, or may be added to the reaction system under temperature conditions suitable for the polycondensation reaction. In the former case, the progress of the polycondensation reaction can be adjusted by adding an esterification catalyst at a temperature suitable for the polycondensation reaction.

[0069] (iii) A method of carrying out the reaction under conditions where the polycondensation reaction step (A) of the raw material monomers of the polyester resin and the addition polymerization reaction step (B) of the raw material monomers of the styrene resin proceed in parallel In this method, step (A) and step (B) are carried out in parallel under temperature conditions suitable for the addition polymerization reaction, the temperature is raised, and under temperature conditions suitable for the polycondensation reaction, if necessary, a raw material monomer of a polyester resin having a valence of 3 or more that serves as a crosslinking agent is added to the polymerization system, and it is preferable to further carry out the polycondensation reaction of step (A). At that time, under temperature conditions suitable for the polycondensation reaction, a polymerization inhibitor can also be added to proceed only with the polycondensation reaction. When both reactive monomers are used, both reactive monomers are involved in the polycondensation reaction as well as the addition polymerization reaction.

[0070] In the method of (i) above, instead of the step (A) of carrying out the polycondensation reaction, a pre-polymerized polyester resin may be used. In the method of (iii) above, when carrying out the reaction under conditions where step (A) and step (B) proceed in parallel, a mixture containing the raw material monomers of the styrene resin can also be dropped into a mixture containing the raw material monomers of the polyester resin and reacted.

[0071] The methods of (i) to (iii) above are preferably carried out in the same container.

[0072] The mass ratio of the polyester resin to the styrene resin in the composite resin (polyester resin / styrene resin) is preferably 98 / 2 or less, more preferably 95 / 5 or less, still more preferably 90 / 10 or less from the viewpoint of improving the dispersibility of the raw materials in the toner, and is preferably 60 / 40 or more, more preferably 70 / 30 or more, still more preferably 75 / 25 or more from the viewpoint of low-temperature fixability. In the above calculation, the mass of the polyester resin is the amount obtained by subtracting the amount of the reaction water (calculated value) dehydrated by the polycondensation reaction from the mass of the raw material monomers of the polyester resin used, and the amounts of both reactive monomers are included in the amount of the raw material monomers of the polyester resin. Also, the amount of the styrene resin is the total amount of the raw material monomers of the styrene resin.

[0073] The softening point of the amorphous polyester resin is preferably 70°C or higher, more preferably 90°C or higher, still more preferably 100°C or higher from the viewpoint of charge stability, and is preferably 170°C or lower, more preferably 160°C or lower, still more preferably 150°C or lower from the viewpoint of low-temperature fixability.

[0074] Note that the amorphous polyester resin may be composed of resins having different softening points from the viewpoints of low-temperature fixability and fixing width. The difference in the softening points of the two resins is preferably 10°C or more, more preferably 20°C or more, and is preferably 60°C or less, more preferably 40°C or less.

[0075] The softening point of the amorphous polyester resin with the higher softening point (resin AH) is preferably 100°C or higher, more preferably 110°C or higher, still more preferably 120°C or higher from the viewpoint of fixing width, and is preferably 170°C or lower, more preferably 160°C or lower, still more preferably 150°C or lower from the viewpoint of low-temperature fixability.

[0076] Also, from the viewpoint of charge stability, the softening point of the amorphous polyester resin (resin AL) with the lower softening point is preferably 70°C or higher, more preferably 90°C or higher, still more preferably 100°C or higher, and from the viewpoint of low-temperature fixability, it is preferably 130°C or lower, more preferably 125°C or lower, still more preferably 120°C or lower.

[0077] The mass ratio of resin AH to resin AL (resin AH / resin AL) is preferably 10 / 90 or higher, more preferably 20 / 80 or higher, still more preferably 30 / 70 or higher, and is preferably 90 / 10 or lower, more preferably 80 / 20 or lower, still more preferably 75 / 25 or lower.

[0078] From the viewpoint of storage stability, the glass transition temperature of the amorphous polyester resin is preferably 40°C or higher, more preferably 50°C or higher, and from the viewpoint of low-temperature fixability, it is preferably 80°C or lower, more preferably 70°C or lower.

[0079] From the viewpoint of pigment dispersibility, the acid value of the amorphous polyester resin is preferably 5 mgKOH / g or higher, more preferably 10 mgKOH / g or higher, and from the viewpoint of charge stability, it is preferably 50 mgKOH / g or lower, more preferably 40 mgKOH / g or lower.

[0080] From the viewpoint of charge stability, the content of the amorphous polyester resin in the total amount of the crystalline polyester resin and the amorphous polyester resin is preferably 65% by mass or higher, more preferably 70% by mass or higher, still more preferably 75% by mass or higher, and is preferably 95% by mass or lower, more preferably 90% by mass or lower, still more preferably 85% by mass or lower.

[0081] The mass ratio of the amorphous polyester resin to the crystalline polyester resin (amorphous polyester resin / crystalline polyester resin) is preferably 65 / 35 or more, more preferably 70 / 30 or more, still more preferably 75 / 25 or more, from the viewpoints of low-temperature fixing property and charge stability, and is preferably 95 / 5 or less, more preferably 90 / 10 or less, still more preferably 85 / 15 or less.

[0082] Examples of other binder resins include vinyl resins such as styrene-acrylic resins, epoxy resins, polycarbonates, polyurethanes, and composite resins containing two or more of these resins.

[0083] The total content of the crystalline polyester resin and the amorphous polyester resin is preferably 70% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, still more preferably 95% by mass or more, still more preferably 100% by mass in the binder resin.

[0084] Also, the content of the binder resin is preferably 60% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more in the toner, and is preferably less than 100% by mass, more preferably 98% by mass or less, still more preferably 95% by mass or less.

[0085] As described above, the colorant contains PR122 as the first magenta pigment and PR57:1 and / or PR185 as the second magenta pigment in order to approach the magenta color of Japan Color. PR185 is preferred as the second magenta pigment.

[0086] The mass ratio of the first magenta pigment to the second magenta pigment (first magenta pigment / second magenta pigment) is preferably 10 / 90 or more, more preferably 40 / 60 or more, still more preferably 55 / 45 or more, and is preferably 90 / 10 or less, more preferably 80 / 20 or less, still more preferably 70 / 30 or less.

[0087] The colorant may contain other colorants as long as the effects of the present invention are not impaired, but the total content of the above-mentioned first magenta pigment and second magenta pigment is preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, and still more preferably 100% by mass in the colorant. Examples of other colorants include magenta pigments such as brilliant fast scarlet, rhodamine-B base, solvent red 49, solvent red 146, etc., cyan pigments, yellow pigments, and the like.

[0088] The content of the colorant is preferably 1 part by mass or more, more preferably 3 parts by mass or more, still more preferably 5 parts by mass or more, and preferably 15 parts by mass or less, more preferably 12 parts by mass or less, still more preferably 10 parts by mass or less, based on 100 parts by mass of the binder resin.

[0089] In addition to the binder resin and the colorant, the toner of the present invention may contain additives such as a release agent, a charge control agent, magnetic powder, a fluidity improver, a conductivity adjuster, a reinforcing filler such as a fibrous substance, an antioxidant, and a cleaning property improver.

[0090] Examples of the release agent include hydrocarbon waxes such as polypropylene wax, polyethylene wax, ethylene-propylene copolymer wax, microcrystalline wax, paraffin wax, Fischer-Tropsch wax, and their oxides; ester waxes such as carnauba wax, montan wax, and their deacidified waxes, fatty acid ester waxes; fatty acid amides, fatty acids, higher alcohols, fatty acid metal salts, etc. These can be used alone or in combination of two or more.

[0091] From the viewpoint of the transferability of the toner, the melting point of the release agent is preferably 60°C or higher, more preferably 70°C or higher, and from the viewpoint of low-temperature fixability, it is preferably 160°C or lower, more preferably 140°C or lower, still more preferably 120°C or lower, and still more preferably 110°C or lower.

[0092] From the viewpoints of the low-temperature fixability and offset resistance of the toner and the dispersibility in the binder resin, the content of the release agent is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, still more preferably 1.5 parts by mass or more, and preferably 10 parts by mass or less, more preferably 8 parts by mass or less, still more preferably 7 parts by mass or less, based on 100 parts by mass of the binder resin.

[0093] The charge control agent is not particularly limited, and may contain either a positive charge control agent or a negative charge control agent.

[0094] Examples of the positive charge control agent include nigrosine dyes such as "Nigrosine Base EX", "Oil Black BS", "Oil Black SO", "Bontron N-01", "Bontron N-04", "Bontron N-07", "Bontron N-09", "Bontron N-11", "Bontron N-79" (manufactured by Orient Chemical Industries Co., Ltd., etc.); triphenylmethane dyes containing a tertiary amine in the side chain; quaternary ammonium salt compounds such as "Bontron P-51" (manufactured by Orient Chemical Industries Co., Ltd.), cetyltrimethylammonium bromide, "COPY CHARGE PX VP435" (manufactured by Clariant, etc.); polyamine resins such as "AFP-B" (manufactured by Orient Chemical Industries Co., Ltd., etc.); imidazole derivatives such as "PLZ-2001", "PLZ-8001" (manufactured by Shikoku Kasei Kogyo Co., Ltd., etc.); styrene-acrylic resins such as "FCA-701PT", "FCA-201-PS" (manufactured by Fujikura Kasei Co., Ltd., etc.).

[0095] In addition, examples of the negative charge control agent include metal-containing azo dyes such as "Valifast Black 3804", "Bontron S-31", "Bontron S-32", "Bontron S-34", "Bontron S-36" (manufactured by Orient Chemical Industries, Ltd.), "Eisenspirone Black TRH", "T-77" (manufactured by Hodogaya Chemical Co., Ltd.), etc.; metal compounds of benzoic acid compounds such as "LR-147", "LR-297" (manufactured by Nippon Carlit Co., Ltd.), etc.; metal compounds of salicylic acid compounds such as "Bontron E-81", "Bontron E-84", "Bontron E-88", "Bontron E-304" (manufactured by Orient Chemical Industries, Ltd.), "TN-105" (manufactured by Hodogaya Chemical Co., Ltd.), etc.; copper phthalocyanine dyes; quaternary ammonium salts such as "COPY CHARGE NX VP434" (manufactured by Clariant), nitroimidazole derivatives, etc.; and organometallic compounds, etc.

[0096] From the viewpoint of the charging stability of the toner, the content of the charge control agent is preferably 0.01 part by mass or more, more preferably 0.2 part by mass or more, and preferably 10 parts by mass or less, more preferably 5 parts by mass or less, still more preferably 3 parts by mass or less, and still more preferably 2 parts by mass or less with respect to 100 parts by mass of the binder resin.

[0097] From the viewpoint of the dispersibility of the colorant, the toner of the present invention is preferably produced by a method including a step of melt-kneading a mixture containing a binder resin and a colorant.

[0098] The mixture to be melt-kneaded is preferably mixed in advance with a mixer such as a Henschel mixer or a ball mill, and then supplied to an open roll type kneader.

[0099] For melt-kneading, known kneaders such as a closed kneader, a single-screw or twin-screw extruder, and an open roll type kneader can be used. In the present invention, since the aggregation of the pigment can be further reduced by giving a physically high kneading share, it is preferable to use an open roll type kneader.

[0100] An open roll type twin-screw kneader is a kneader equipped with two rolls, and the kneading section is not sealed but open, and can easily dissipate the kneading heat generated during melt kneading. The open roll type twin-screw kneader used in the present invention is provided with a raw material supply port and a kneaded product discharge port provided along the axial direction of the roll, and from the viewpoint of production efficiency, it is preferably a continuous open roll type twin-screw kneader.

[0101] The open roll type twin-screw kneader used in the present invention is preferably a kneader equipped with two rolls having different peripheral speeds, that is, two rolls of a roll with a high peripheral speed (high rotation roll) and a roll with a low peripheral speed (low rotation roll). In the present invention, from the viewpoint of the dispersibility of the kneaded product, it is preferable that the high rotation roll functions as a heating roll and the low rotation roll functions as a cooling roll, that is, it is preferable that the set temperature of the high rotation roll is higher than the set temperature of the low rotation roll. When the set temperatures of the rolls are different on the raw material input side and the kneaded product discharge side, it is preferable that at least on the raw material input side, the set temperature of the high rotation roll is higher than the set temperature of the low rotation roll, and it is more preferable that on both the raw material input side and the kneaded product discharge side, the set temperature of the high rotation roll is higher than the set temperature of the low rotation roll.

[0102] The temperature of the roll can be adjusted, for example, by the temperature of the heat medium passed through the inside of the roll, and each roll may pass heat media with different temperatures by dividing the inside of the roll into two or more parts.

[0103] From the viewpoint of reducing the mechanical force during melt kneading and suppressing heat generation, the temperature of the raw material input side of the high rotation roll is preferably 80 °C or higher, more preferably 100 °C or higher, still more preferably 120 °C or higher, and preferably 160 °C or lower, more preferably 150 °C or lower. From the same viewpoint, the temperature of the raw material input side of the low rotation roll is preferably 25 °C or higher, more preferably 40 °C or higher, and preferably 90 °C or lower, more preferably 80 °C or lower.

[0104] It is preferable that the temperature of the raw material input side of both the high-speed roll and the low-speed roll is higher than that of the kneaded product discharge side. From the viewpoint of preventing the kneaded product from detaching from the roll and reducing the mechanical force and heat generation during melt kneading, the temperature difference between the raw material input side and the kneaded product discharge side is preferably 20°C or more, more preferably 30°C or more, and preferably 60°C or less, more preferably 50°C or less.

[0105] The temperature of the raw material input side of the high-speed roll and the low-speed roll refers to the set temperature at the end of the raw material input side, and the temperature of the kneaded product discharge side refers to the set temperature at the end of the kneaded product discharge side.

[0106] From the viewpoint of reducing the mechanical force and heat generation during kneading, the peripheral speed of the high-speed roll is preferably 2 m / min or more, more preferably 10 m / min or more, still more preferably 25 m / min or more, and preferably 100 m / min or less, more preferably 75 m / min or less, still more preferably 50 m / min or less. From the same viewpoint, the peripheral speed of the low-speed roll is preferably 1 m / min or more, more preferably 5 m / min or more, still more preferably 15 m / min or more, and preferably 90 m / min or less, more preferably 60 m / min or less, still more preferably 30 m / min or less. Also, the ratio of the peripheral speeds of the two rolls (low-speed roll / high-speed roll) is preferably 1 / 10 or more, more preferably 3 / 10 or more, and preferably 9.9 / 10 or less, more preferably 8 / 10 or less.

[0107] Also, there are no particular limitations on the structure, size, material, etc. of each roll. The roll surface has grooves used for kneading, and examples of this shape include linear, spiral, corrugated, and uneven shapes.

[0108] After melt kneading, it is preferable to appropriately cool the kneaded product until it reaches a hardness at which it can be pulverized, and then perform a pulverization and classification step to obtain toner particles. Here, cooling means cooling the kneaded product to 0°C or more and 50°C or less, or cooling it to below the glass transition temperature of the binder resin in the kneaded product.

[0109] In the pulverization of the kneaded product, the kneaded product may be pulverized at once to a desired particle size or may be pulverized step by step. However, from the viewpoints of efficient and more uniform pulverization, it is preferable to carry out the pulverization in two steps of coarse pulverization and fine pulverization.

[0110] Examples of the pulverizer used for coarse pulverization include a hammer mill, a cutter mill, an atomizer, a rotorplex, etc.

[0111] In coarse pulverization, the kneaded product is appropriately coarsely pulverized until the particle size becomes about 0.1 to 3 mm, and then passed through a sieve with an aperture of about 2 to 3 mm. It is preferable that the pulverized product passing through the sieve is used for fine pulverization as a pulverized product having a maximum diameter of 2 to 3 mm or less.

[0112] Examples of the pulverizer used for fine pulverization include jet mills such as a fluidized bed jet mill and a collision plate jet mill, and mechanical mills.

[0113] The degree of fine pulverization is preferably adjusted as appropriate according to the particle size of the target toner particles.

[0114] Examples of the classifier used for classification include an air classifier, an inertial classifier, a sieve classifier, etc. In the classification step, the pulverized product that has not been sufficiently pulverized and removed may be returned to the pulverization step, and the pulverization step and the classification step may be repeated as necessary.

[0115] For the toner of the present invention, in order to improve the transferability, it is preferable to use an external additive. Examples of the external additive include inorganic fine particles such as silica, alumina, titania, zirconia, tin oxide, zinc oxide, and organic fine particles such as melamine resin fine particles and polytetrafluoroethylene resin fine particles, and two or more kinds may be used in combination. Among these, silica is preferable, and from the viewpoint of the transferability of the toner, hydrophobic silica subjected to a hydrophobization treatment is more preferable.

[0116] Examples of the hydrophobizing agent for hydrophobizing the surface of silica particles include hexamethyldisilazane (HMDS), dimethyldichlorosilane (DMDS), cyclic silazane, silicone oil, aminosilane, octyltriethoxysilane (OTES), methyltriethoxysilane, and the like.

[0117] From the viewpoints of the chargeability, fluidity, and transferability of the toner, the average particle diameter of the external additive is preferably 10 nm or more, more preferably 15 nm or more, and preferably 250 nm or less, more preferably 200 nm or less, and even more preferably 90 nm or less.

[0118] The external addition treatment by mixing toner particles and the external additive can be performed according to a conventional method, and a mixer such as a Henschel mixer can be used.

[0119] From the viewpoints of the chargeability, fluidity, and transferability of the toner, the content of the external additive is preferably 0.05 part by mass or more, more preferably 0.1 part by mass or more, and even more preferably 0.3 part by mass or more with respect to 100 parts by mass of the toner particles before being treated with the external additive, and preferably 5 parts by mass or less, more preferably 3 parts by mass or less.

[0120] The volume median particle diameter (D 50 ) of the toner of the present invention is preferably 4 μm or more, more preferably 5 μm or more, and preferably 6.5 μm or less, more preferably 6 μm or less. In the present specification, the volume median particle diameter (D 50 ) means the particle diameter at which the cumulative volume frequency calculated by the volume fraction becomes 50% when calculated from the smaller particle diameter side. Further, when the toner is treated with an external additive, the volume median particle diameter of the toner particles before being treated with the external additive is taken as the volume median particle diameter of the toner.

[0121] The toner of the present invention can be used in an image forming apparatus using a one-component development system or a two-component development system as a one-component development toner as it is or as a two-component development toner used by mixing with a carrier.

Examples

[0122] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Physical properties such as those of the resin were measured by the following methods.

[0123] 〔Softening point of resin〕 Using a flow tester "CFT-500D" (manufactured by Shimadzu Corporation), while heating 1 g of the sample at a temperature rising rate of 6°C / min, a load of 1.96 MPa is applied by a plunger and extruded from a nozzle with a diameter of 1 mm and a length of 1 mm. Plot the plunger descent amount of the flow tester against the temperature, and the temperature at which half of the sample has flowed out is defined as the softening point.

[0124] 〔Maximum peak temperature of endotherm of resin〕 Using a differential scanning calorimeter "Q-100" (manufactured by TA Instruments Japan Co., Ltd.), weigh 0.01 - 0.02 g of the sample into an aluminum pan, cool it from room temperature (25°C) to 0°C at a temperature decreasing rate of 10°C / min, and maintain it at 0°C for 1 minute. Then, measure it at a temperature rising rate of 10°C / min. Among the observed endothermic peaks, the temperature of the peak with the largest peak area is defined as the maximum peak temperature of endotherm. For a crystalline resin, the maximum peak temperature of endotherm is defined as the melting point.

[0125] 〔Glass transition temperature of resin〕 Using a differential scanning calorimeter "Q-100" (manufactured by TA Instruments Japan Co., Ltd.), weigh 0.01 - 0.02 g of the sample into an aluminum pan, heat it up to 200°C, and then cool it from that temperature to 0°C at a temperature decreasing rate of 10°C / min. Next, heat the sample at a temperature rising rate of 10°C / min and measure the endothermic peak. The temperature at the intersection of the extension line of the baseline below the maximum peak temperature of endotherm and the tangent line showing the maximum slope from the rising part of the peak to the apex of the peak is defined as the glass transition temperature.

[0126] 〔Acid value of resin〕 Measure based on the method of JIS K 0070:1992. However, for the measurement solvent only, change from the mixed solvent of ethanol and ether specified in JIS K 0070 to a mixed solvent of acetone and toluene (acetone:toluene = 1:1 (volume ratio)) for amorphous resins, and to a mixed solvent of chloroform and dimethylformamide (chloroform:dimethylformamide = 7:3 (volume ratio)) for crystalline resins, respectively.

[0127] 〔Melting point of release agent〕 Using a differential scanning calorimeter "Q-100" (manufactured by TA Instruments Japan Co., Ltd.), weigh 0.01 to 0.02 g of the sample into an aluminum pan, heat it up to 200 °C at a heating rate of 10 °C / min, and then cool it from that temperature to 0 °C at a cooling rate of 10 °C / min. Next, heat the sample up to 200 °C at a heating rate of 10 °C / min and measure it, and take the maximum peak temperature of the endotherm as the melting point.

[0128] 〔Average particle diameter of external additive〕 The average particle diameter refers to the number-average particle diameter. Measure the particle diameters (average value of the major axis and minor axis) of 500 particles from a scanning electron microscope (SEM) photograph, and take their number-average value.

[0129] 〔Volume median diameter (D 50 ) of toner〕 · Measuring instrument: "Coulter Multisizer (registered trademark) III" (manufactured by Beckman Coulter, Inc.) · Aperture diameter: 100 μm · Analysis software: "Multisizer (registered trademark) III Version 3.51" (manufactured by Beckman Coulter, Inc.) · Electrolyte: "Isoton (registered trademark) II" (manufactured by Beckman Coulter, Inc.) · Dispersion liquid: A solution prepared by dissolving polyoxyethylene lauryl ether "Emulgen (registered trademark) 109P" [manufactured by Kao Corporation, HLB (Griffin) = 13.6] in the electrolyte to adjust to 5% by mass. ·Dispersion conditions: Add 10 mg of the measurement sample to 5 mL of the dispersion liquid, disperse it for 1 minute with an ultrasonic disperser (machine name: US-1 manufactured by SND Co., Ltd., output: 80 W), then add 25 mL of the electrolytic solution, and further disperse it for 1 minute with the ultrasonic disperser to prepare a sample dispersion liquid. ·Measurement conditions: By adding the sample dispersion liquid to 100 mL of the electrolytic solution, adjust it to a concentration at which the particle sizes of 30,000 particles can be measured in 20 seconds, then measure 30,000 particles, and determine the volume median particle size (D 50 ) from its particle size distribution.

[0130] Resin production example 1 Put the alcohol component, fumaric acid, esterification catalyst, and polymerization inhibitor shown in Table 1 into a 10-liter four-necked flask equipped with a nitrogen introduction tube, a dehydrator, a stirrer, and a thermocouple, heat it up to 230 °C in a mantle heater under a nitrogen atmosphere, and perform polycondensation for 7 hours. Then, cool it down to 200 °C, add trimellitic anhydride, then heat it up to 210 °C, and perform a polycondensation reaction to obtain an amorphous polyester resin (resin A1). The physical properties of the obtained resin are shown in Table 1.

[0131]

Table 1

[0132] Resin production example 2 The raw material monomers, both reactive monomers, and esterification catalysts of the polyester resin other than trimellitic anhydride shown in Table 2 were placed in a 10-liter four-necked flask equipped with a dehydration tube equipped with a nitrogen introduction tube, a stirrer, and a thermocouple, and heated to 160 °C in a mantle heater under a nitrogen atmosphere. Thereafter, a mixture of the raw material monomers and polymerization initiator of the styrene resin was dropped over 1 hour to carry out polymerization. Thereafter, the temperature was raised to 200 °C and aged for 1 hour to produce a styrene resin in the reaction system. Thereafter, the temperature was raised to 230 °C over 1 hour, and after confirming that all the solid monomers had melted and reacted, the pressure was reduced to 8 kPa and dehydration condensation was carried out for 1 hour. Thereafter, the temperature was lowered to 210 °C, trimellitic anhydride was added, and after reacting for another 1 hour, the pressure was reduced to 8 kPa, and the reaction was carried out until the softening point shown in Table 2 was reached to obtain an amorphous composite resin (resin A2). The physical properties of the obtained resin are shown in Table 2.

[0133]

Table 2

[0134] Resin Production Example 3 The alcohol component, carboxylic acid component, and esterification catalyst shown in Table 3 were placed in a 10-liter four-necked flask equipped with a dehydration tube equipped with a nitrogen introduction tube, a stirrer, and a thermocouple, and the temperature was raised to 200 °C over 8 hours in a mantle heater under a nitrogen atmosphere. Thereafter, the reaction was carried out at 8 kPa until the softening point shown in Table 3 was reached to obtain crystalline polyester resins (resins C1 to C5). The physical properties of the obtained resins are shown in Table 3.

[0135]

Table 3

[0136] Examples 1 to 5, Comparative Examples 1 and 2, and Reference Example 1 40 parts by mass of Resin A1, 40 parts by mass of Resin A2, 20 parts by mass of the crystalline polyester resin shown in Table 4, the colorant shown in Table 4, 4 parts by mass of the mold release agent "HNP-9" (manufactured by Nippon Seiro Co., Ltd., paraffin wax, melting point: 80°C), and 0.5 parts by mass of the charge control agent "Bontron E-304" (manufactured by Orient Chemical Industries Co., Ltd.) were thoroughly mixed with a Henschel mixer and then melt-kneaded under the conditions shown below.

[0137] A continuous two-open-roll kneader "Neidex" (manufactured by Mitsui Mining Co., Ltd., roll outer diameter: 14 cm, effective roll length: 80 cm) was used. The operating conditions of the continuous two-open-roll kneader were a peripheral speed of 32.4 m / min for the high-speed roll (front roll), a peripheral speed of 21.7 m / min for the low-speed roll (back roll), and a roll gap of 0.1 mm. The temperature of the heating medium and the cooling medium inside the roll were 145°C on the raw material input side and 100°C on the kneaded product discharge side of the high-speed roll, and 75°C on the raw material input side and 35°C on the kneaded product discharge side of the low-speed roll. Also, the supply rate of the raw material mixture was 10 kg / h, and the average residence time was about 3 minutes.

[0138] The obtained kneaded product was cooled and roughly pulverized by a pulverizer "Rotoplex" (manufactured by Hosokawa Micron Corporation), and a roughly pulverized product with a maximum diameter of 2 mm or less was obtained using a sieve with an opening of 2 mm. The obtained roughly pulverized product was finely pulverized by adjusting the pulverization pressure so that the volume median diameter (D 50 ) was 5.5 μm using an air classifier "DS2 type" (impact plate type, manufactured by Nippon Pneumatic Mfg. Co., Ltd.). The obtained finely pulverized product was classified by adjusting the static pressure (internal pressure) so that the volume median diameter (D 50 ) was 6.0 μm using an air classifier "DSX2 type" (manufactured by Nippon Pneumatic Mfg. Co., Ltd.) to obtain toner particles.

[0139] To 100 parts by mass of the obtained toner particles, 1.0 part by mass of "R972" (hydrophobic silica, manufactured by Nippon Aerosil Co., Ltd., hydrophobizing agent: DMDS, average particle diameter: 16 nm) and 1.0 part by mass of "RX50" (hydrophobic silica, manufactured by Nippon Aerosil Co., Ltd., hydrophobizing agent: HMDS, average particle diameter: 40 nm) were added as external additives, and the mixture was mixed with a Henschel mixer at 3700 r / min for 3 minutes to perform external additive treatment, thereby obtaining toner.

[0140] Example 6 In the melt-kneading step, toner was obtained in the same manner as in Example 1 except that a co-rotating twin-screw extruder "PCM-30" (manufactured by Ikegai Corporation, shaft diameter 2.9 cm, shaft cross-sectional area 7.06 cm 2 ) was used. The operating conditions of the twin-screw extruder were a barrel set temperature of 100°C, a shaft rotation speed of 200 r / min (circumferential speed of shaft rotation 0.30 m / sec), and a mixture supply rate of 10 kg / h.

[0141] Test Example 1 [Charge stability] 50 g of carrier (Japan Society for Imaging Science and Technology standard carrier N-01) and 1.5 g of toner were placed in a 50 mL polyethylene container and stirred with a Turbula mixer for 5 minutes. With the lid of the container open, the mixture (developer) after stirring was left in a high-temperature and high-humidity (HH) environment at a temperature of 32.5°C and a relative humidity of 85% for 24 hours. After closing the lid and stirring with a Turbula mixer for 5 minutes, the measured charge amount was defined as the charge amount in the HH environment (HH charge amount). On the other hand, the mixture after stirring was left in a low-temperature and low-humidity (LL) environment at a temperature of 10°C and a relative humidity of 20% for 24 hours. After closing the lid and stirring with a Turbula mixer for 5 minutes, the measured charge amount was defined as the charge amount in the LL environment (LL charge amount). The value of HH charge amount / LL charge amount was calculated and evaluated as charge stability. The results are shown in Table 4.

[0142] Test Example 2 [Color tone] The toner was loaded into the toner cartridge of a non-magnetic one-component developing device "COREFIDO C844dnw" (manufactured by Oki Electric Industry Co., Ltd.), and Aurora coated paper (84.9 g / m 2) A solid image with an image density of 1.5 was printed. The magenta color of Japan Color (L * = 46.3, a * = 76.1, b * = -2.9) was used as a reference, and the color difference (ΔE) was measured with a color difference meter (eXact manufactured by X-Rite). The color was evaluated according to the following evaluation criteria. The results are shown in Table 4. 〔Evaluation Criteria〕 A: ΔE ≦ 5 B: 5 < ΔE ≦ 7.5 C: ΔE > 7.5

[0143]

Table 4

[0144] From the above results, it can be seen that the toners of Examples 1 to 6 are excellent in charging stability and have colors closer to the magenta color of Japan Color, even when compared with Reference Example 1 using PR269 as the magenta pigment. In particular, from the comparison between Example 1 and Example 6, it can be seen that by using an open roll kneader for melt kneading, the charging stability is further improved and the color approaches that of Japan Color. On the other hand, the toner of Comparative Example 1 containing a crystalline polyester resin with too low an ester group concentration lacks charging stability, and the toner of Comparative Example 2 containing only PR122 as the magenta pigment has good charging stability but a large color difference from Japan Color.

Industrial Applicability

[0145] The magenta toner for electrostatic charge image development of the present invention is suitably used for developing latent images formed in electrostatic charge image development methods, electrostatic recording methods, electrostatic printing methods, etc.

Claims

1. A magenta toner for electrostatic charge image development containing a binder resin and a colorant, wherein the binder resin contains a crystalline polyester resin having an ester group concentration of 6.0 mmol / g or more and 12.0 mmol / g or less, and the colorant contains, as a first magenta pigment, C.I. Pigment Red 122, and as a second magenta pigment, C.I. Pigment Red 57:1 and / or C.I. Pigment Red 185. A magenta toner for electrostatic charge image development.

2. The magenta toner for electrostatic charge image development according to claim 1, wherein the content of the crystalline polyester resin is 5% by mass or more and 35% by mass or less in the binder resin.

3. The magenta toner for electrostatic charge image development according to claim 1 or 2, wherein the mass ratio of the first magenta pigment to the second magenta pigment is 10 / 90 or more and 90 / 10 or less.

4. The magenta toner for electrostatic charge image development according to any one of claims 1 to 3, wherein the volume median particle diameter of the toner is 6.5 μm or less.

5. A method for manufacturing a magenta toner for electrostatic charge image development according to any one of claims 1 to 4, the method comprising a step of melt-kneading a mixture containing a binder resin and a colorant using an open roll type kneader. A method for manufacturing a magenta toner for electrostatic charge image development.

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