Manufacturing method of electrostatic charge image developing toner

Abstract

To provide a manufacturing method of an electrostatic charge image developing toner excellent in durability under high temperature and humidity.SOLUTION: A manufacturing method of an electrostatic charge image developing toner includes: a step (1) of fusing and kneading a mixture containing at least a binder resin, toner powder, and silica by using an open roll-type kneader; and a step (2) of pulverizing and classifying a kneaded object obtained in the step (1) so as to acquire toner base particles. The binder resin contains a crystalline polyester resin C. The content of the silica in the toner base particles is 0.8 mass% or more and 15 mass% or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for manufacturing an electrostatic charge image developing toner used for developing a latent image formed in an electrophotographic method, an electrostatic recording method, an electrostatic printing method, or the like.

Background Art

[0002] From the viewpoint of enhancing the dispersibility of internal additives, there is a method of utilizing fine powder removed in a classification step in the manufacturing process of an electrostatic charge image developing toner (hereinafter also simply referred to as "toner") (see Patent Document 1).

[0003] Also, from the viewpoint of achieving both storage stability and fluidity, incorporation of hydrophobic silica into toner particles has been studied (see Patent Document 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] When a crystalline polyester resin is used as the binder resin of the toner, while it has excellent low-temperature fixability, there is a problem that its durability under high temperature and high humidity tends to decrease.

[0006] The present invention relates to a method for manufacturing an electrostatic charge image developing toner having excellent durability under high temperature and high humidity.

Means for Solving the Problems

[0007] The present invention relates to a method for producing a toner for electrostatic charge image development, comprising: a step (1) of melt-kneading at least a binder resin, and a mixture containing toner powder and silica using an open roll kneader; and a step (2) of pulverizing and classifying the kneaded product obtained in the step (1) to obtain toner mother particles, wherein the binder resin contains a crystalline polyester resin C, and the content of silica in the toner mother particles is 0.8% by mass or more and 15% by mass or less.

Advantages of the Invention

[0008] By the method of the present invention, a toner for electrostatic charge image development excellent in durability under high temperature and high humidity can be obtained.

Embodiments for Carrying Out the Invention

[0009] The present invention uses a crystalline polyester resin as a binder resin, and when producing a toner by a melt-kneading method, a mixture containing toner powder containing the crystalline polyester resin and silica is melt-kneaded with the binder resin using an open roll kneader to obtain a toner with a predetermined amount of silica added internally. The reason why the toner obtained by the method of the present invention is excellent in durability under high temperature and high humidity is not clear, but it is presumed as follows. The following mechanism is a presumption and is not limited thereto.

[0010] It is presumed that using a crystalline polyester resin as the binder resin of the toner reduces the durability under high temperature and high humidity because the crystalline polyester resin is inferior in mechanical strength in terms of molecular skeleton, has high hydrophobicity, and has low dispersibility in toner particles. In order to improve this, an attempt was made to add inorganic fine particles such as silica to the toner to improve the mechanical strength by the interaction (so-called filler effect) generated with the molecular chains of the resin, but the expected effect was not obtained even when silica was added during melt-kneading. Therefore, as a result of intensive studies by the present inventors, by using an open roll type kneader during melt kneading and melt kneading a mixture of toner powder and silica in advance with a binder resin to produce toner particles, it has been found that the durability under high temperature and high humidity is improved even in the production of toner containing a crystalline polyester resin as a binder resin. This is because, while using an open roll type kneader with a large kneading share, silica, which is likely to aggregate and has low dispersibility in the kneaded material, is mixed with the toner powder in advance and internally added to the toner particles, thereby suppressing aggregation in the kneaded material and realizing melt kneading in a state where the dispersibility of both the crystalline polyester resin and silica is improved, and it is considered that the interaction between the two can be effectively exhibited.

[0011] The method for producing the toner of the present invention includes the following steps (1) and (2).

[0012] Step (1) is a step of melt kneading at least a binder resin and a mixture containing toner powder and silica using an open roll type kneader, and the binder resin contains a crystalline polyester resin C.

[0013] In the present invention, the crystalline polyester resin C is preferably a polycondensate of an alcohol component containing an aliphatic diol and a carboxylic acid component containing an aliphatic dicarboxylic acid compound.

[0014] 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.

[0015] The aliphatic diol has 2 or more carbon atoms, and from the viewpoint of low-temperature fixability, it is preferably 14 or less, more preferably 10 or less, still more preferably 8 or less, still more preferably 6 or less, and still more preferably 4 or less.

[0016] 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.

[0017] 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 in the alcohol component, and is 100 mol% or less.

[0018] 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 such as trimethylolpropane having 3 or more valences.

[0019] Examples of the aliphatic dicarboxylic acid-based compound include succinic acid (number of carbon atoms: 4), fumaric acid (number of carbon atoms: 4), adipic acid (number of carbon atoms: 6), suberic acid (number of carbon atoms: 8), azelaic acid (number of carbon atoms: 9), sebacic acid (number of carbon atoms: 10), dodecanedioic acid (number of carbon atoms: 12), tetradecanedioic acid (number of carbon atoms: 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 number of carbon atoms of the alkyl group is not included in the above number of carbon atoms.

[0020] The number of carbon atoms of the aliphatic dicarboxylic acid-based compound is preferably 4 or more, more preferably 6 or more, still more preferably 8 or more, and from the viewpoint of adjusting the ester group concentration, it is preferably 14 or less, more preferably 12 or less.

[0021] The content of the aliphatic dicarboxylic acid 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 from the viewpoint of hydrophobicity in the carboxylic acid component.

[0022] Examples of other carboxylic acid components include aromatic dicarboxylic acid compounds such as phthalic acid, isophthalic acid, and terephthalic acid, and polyvalent carboxylic acid compounds such as trimellitic acid and pyromellitic acid.

[0023] Furthermore, from the viewpoint of durability, it is preferable that the alcohol component and / or carboxylic acid component of the crystalline polyester resin C contains a monofunctional monomer.

[0024] 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.

[0025] From the viewpoint 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 viewpoint of low-temperature fixability, it is preferably 22 or less, more preferably 20 or less, still more preferably 18 or less.

[0026] 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 compounds such as alkyl esters in which the carbon number of the alkyl group of these acids is 1 or more and 3 or less.

[0027] From the viewpoint of hydrophobicity, the number of carbon atoms in the aliphatic monocarboxylic acid compound is preferably 10 or more, more preferably 12 or more, still more preferably 14 or more, and from the viewpoint 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 compound is an alkyl ester, the number of carbon atoms in the alkyl group is not included in the above number of carbon atoms.

[0028] 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 viewpoint of low-temperature fixability, it is preferably 30 mol% or less, more preferably 20 mol% or less, still more preferably 15 mol% or less.

[0029] In addition, in this specification, macromonomers and hydroxycarboxylic acids are not included in the alcohol component and the carboxylic acid component.

[0030] The equivalent ratio (COOH group / OH group) of the carboxyl group of the carboxylic acid component to the hydroxyl group of the alcohol component is preferably 0.8 or more, more preferably 0.9 or more from the viewpoint of charge stability, and from the viewpoint of low-temperature fixability, it is preferably 1.2 or less, more preferably 1.1 or less.

[0031] In the present invention, the ester group concentration of the crystalline polyester resin C that can be adjusted by the raw material monomer composition is preferably 5.0 mmol / g or more, more preferably 6.0 mmol / g or more, still more preferably 7.0 mmol / g or more, and preferably 12.0 mmol / g or less, more preferably 11.0 mmol / g or less, still more preferably 10.0 mmol / g or less.

[0032] In the present invention, the ester group concentration of the polyester resin is calculated from the following formula.

[0033]

Number

[0034] [In the formula, A is the total amount (mol) of all ester bonds formed 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.]

[0035] The crystalline polyester resin C 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.

[0036] 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 0.1 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.

[0037] 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.

[0038] From the viewpoint of durability, the softening point of the crystalline polyester resin C is preferably 50°C or higher, more preferably 65°C or higher, still more preferably 70°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.

[0039] Note that 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]. A crystalline resin is a resin having a crystallinity index of 0.6 or more and 1.4 or less. On the other hand, an 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 or is less than 0.6. The crystallinity of the resin can be adjusted by the types and ratios 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 having 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.

[0040] From the viewpoint of durability, the melting point of the crystalline polyester resin C is preferably 50°C or higher, more preferably 65°C or higher, still more preferably 70°C or higher, and from the viewpoint of low-temperature fixability, it is preferably 130°C or lower, more preferably 120°C or lower, still more preferably 100°C or lower.

[0041] From the viewpoint of low-temperature fixability, the acid value of the crystalline polyester resin C is preferably 1 mgKOH / g or more, more preferably 3 mgKOH / g or more, and from the viewpoint of durability, it is preferably 20 mgKOH / g or less, more preferably 15 mgKOH / g or less.

[0042] From the viewpoint of low-temperature fixability, the content of the crystalline polyester resin C in the binder resin is preferably 5% by mass or more, more preferably 10% by mass or more, still more preferably 15% by mass or more, and from the viewpoint of durability, it is preferably 35% by mass or less, more preferably 30% by mass or less, still more preferably 25% by mass or less.

[0043] From the viewpoint of durability, it is further preferable that the binder resin contains an amorphous polyester resin.

[0044] 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.

[0045] 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.

[0046] As the alkylene oxide adduct of bisphenol A, the formula (I):

[0047]

Chemical formula

[0048] (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 each a positive number. 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, still more preferably 4 or less) The compound represented by the formula is preferable.

[0049] From the perspective of low-temperature fixability, the content of the alkylene oxide adduct of bisphenol A in the alcohol component is preferably 70 mol% or more, more preferably 80 mol% or more, still more preferably 90 mol% or more, and even more preferably 95 mol% or more, and is 100 mol% or less.

[0050] Examples of other alcohol components include aliphatic diols, bisphenol A, hydrogenated bisphenol A, sorbitol, pentaerythritol, glycerin, and polyhydric alcohols having three or more valences such as trimethylolpropane.

[0051] Examples of the carboxylic acid component include aromatic dicarboxylic acid compounds, aliphatic dicarboxylic acid compounds, and polycarboxylic acid compounds having three or more valences.

[0052] 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.

[0053] 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.

[0054] Examples of the polycarboxylic acid compounds having three or more valences include trimellitic acid, pyromellitic acid, anhydrides of these acids, and alkyl esters of these acids having 1 to 3 carbon atoms.

[0055] Note that the alcohol component may appropriately contain monohydric alcohols, and the carboxylic acid component may appropriately contain monocarboxylic acid compounds.

[0056] 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.

[0057] 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 C, except that a suitable reaction temperature is 160°C or more, more preferably 180°C or more, and 250°C or less, more preferably 240°C or less.

[0058] 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").

[0059] 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.

[0060] In addition, the styrene resin may contain a (meth)acrylic acid alkyl ester having an alkyl group with 7 or more carbon atoms as a raw material monomer. Examples of the (meth)acrylic acid alkyl ester 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 this 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” indicates acrylic acid, methacrylic acid, or both of them.

[0061] From the viewpoint of improving the low-temperature fixability of the toner, the number of carbon atoms of the alkyl group in the (meth)acrylic acid alkyl ester 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. The number of carbon atoms of the alkyl ester refers to the number of carbon atoms derived from the alcohol component constituting the ester.

[0062] The raw material monomers of the styrene resin may include raw material monomers other than styrene compounds and (meth)acrylic acid alkyl esters, 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.

[0063] 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, 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, more preferably 170 °C or lower.

[0064] 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.

[0065] 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 via 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.

[0066] 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 at least one selected from the group consisting of acrylic acid, methacrylic acid, fumaric acid, maleic acid, and maleic anhydride is more preferable, and at least one selected from the group consisting of acrylic acid, methacrylic acid, and fumaric acid is even more preferable from the viewpoint of the reactivity of the polycondensation reaction and the addition polymerization reaction. 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.

[0067] The amount of the bifunctional monomer used is preferably 1 mol or more, more preferably 2 mol or more, per 100 mol of the alcohol component 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. 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, and even more preferably 10 mol or less.

[0068] 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 raw materials in the toner.

[0069] (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 valency that serve as a crosslinking agent are added to the polymerization system to further proceed with the polycondensation reaction in step (A) and the reaction with the bifunctional monomer.

[0070] (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.

[0071] (iii) A method of performing a 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, 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 as needed, 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.

[0072] In the method of (i) above, instead of the step (A) of performing the polycondensation reaction, a previously polymerized polyester resin may be used. In the method of (iii) above, when performing 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.

[0073] The methods of (i) to (iii) above are preferably carried out in the same container.

[0074] 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 excluding the amount of 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.

[0075] 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.

[0076] Incidentally, the amorphous polyester resin may be composed of two or more 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.

[0077] 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.

[0078] 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.

[0079] 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 preferably 90 / 10 or lower, more preferably 80 / 20 or lower, still more preferably 75 / 25 or lower.

[0080] From the viewpoint of durability, 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 charge stability, it is preferably 80°C or lower, more preferably 70°C or lower.

[0081] From the viewpoint of the dispersibility of silica in the toner mother particles, the acid value of the amorphous polyester resin is preferably 10 mgKOH / g or higher, more preferably 20 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.

[0082] From the viewpoint of charge stability, the content of 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 preferably 95% by mass or lower, more preferably 90% by mass or lower, still more preferably 85% by mass or lower in the total amount of the crystalline polyester resin C and the amorphous polyester resin.

[0083] The mass ratio of the amorphous polyester resin to the crystalline polyester resin C (amorphous polyester resin / crystalline polyester resin C) is preferably 65 / 35 or more, more preferably 70 / 30 or more, still more preferably 75 / 25 or more, and preferably 95 / 5 or less, more preferably 90 / 10 or less, still more preferably 85 / 15 or less, from the viewpoint of achieving both low-temperature fixability and durability.

[0084] 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.

[0085] The total content of the crystalline polyester resin C 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, and still more preferably 100% by mass in the binder resin.

[0086] Also, the content of the binder resin is preferably 60% by mass or more, more preferably 70% by mass or more, still more preferably 75% by mass or more, and preferably less than 100% by mass, more preferably 98% by mass or less, still more preferably 95% by mass or less in the toner.

[0087] In the present invention, the toner powder is a composition containing a binder resin as a main component (60% by mass or more, preferably 80% by mass or more), and preferably contains internal additives such as a colorant, a release agent, and a charge control agent in addition to the binder resin. It is more preferable that the toner powder contains the same internal additives such as a binder resin, a colorant, a release agent, and a charge control agent as those of the toner manufactured by the method of the present invention. The toner powder is preferably a powder obtained by a method including a step of melt-kneading a mixture containing a binder resin and, if necessary, internal additives. Further, the binder resin of the toner powder may contain a crystalline polyester resin, and preferably contains a crystalline polyester resin C' that is the same as or different from the crystalline polyester resin C. The raw material monomers and production method of the crystalline polyester resin C' are the same as those of the crystalline polyester resin C, but the crystalline polyester resin C' is preferably the same as the crystalline polyester resin C. As described later, when the powder removed during classification is reused as a mixture containing the toner powder and silica, the crystalline polyester resin C' becomes the same as the crystalline polyester resin C.

[0088] The content of the crystalline polyester resin C' in the toner powder is preferably 1% by mass or more, more preferably 5% by mass or more, still more preferably 10% by mass or more, and preferably 50% by mass or less, more preferably 45% by mass or less, still more preferably 40% by mass or less.

[0089] From the viewpoint of dispersibility in the toner mother particles, the silica is more preferably hydrophobized hydrophobic silica.

[0090] Examples of the hydrophobizing agent for hydrophobizing the surface of the silica particles include hexamethyldisilazane (HMDS), dimethyldichlorosilane (DMDS), cyclic silazane, silicone oil, aminosilane, octyltriethoxysilane (OTES), and methyltriethoxysilane.

[0091] From the viewpoint of durability, the BET specific surface area of the silica is preferably 10 m 2 / g or more, more preferably 30 m2 / g or more, more preferably 80 m 2 / g or more, and from the viewpoint of dispersibility in the toner mother particles, preferably 350 m 2 / g or less, more preferably 330 m 2 / g or less, more preferably 310 m 2 / g or less.

[0092] The number average particle diameter of the silica is preferably 5 nm or more, more preferably 15 nm or more, and preferably 250 nm or less, more preferably 200 nm or less, still more preferably 100 nm or less, from the viewpoint of dispersibility in the toner mother particles.

[0093] The content of silica in the mixture is preferably 0.8% by mass or more, more preferably 1.5% by mass or more, still more preferably 2% by mass or more, and preferably 25% by mass or less, more preferably 20% by mass or less, still more preferably 15% by mass or less.

[0094] The mixture containing the toner powder and silica may be a mixture obtained by externally adding silica to the classified toner mother particles, or a mixture obtained by mixing silica with the toner powder before classification and then further pulverizing it by pulverizing the kneaded product in the presence of silica during the process of producing the toner powder by the melt-kneading method. However, from the viewpoint of the dispersibility of silica in the toner mother particles, the latter is preferred. Therefore, the mixture containing the toner powder and silica is preferably a mixture obtained by a method including a step of melt-kneading a mixture containing the crystalline polyester resin C' using an open roll type kneader, and a step of pulverizing the obtained kneaded product in the presence of silica, and the particle size may be adjusted by classification during or after pulverization.

[0095] Also, in the present invention, the mixture containing toner powder and silica may be the powder removed during the classification in step (2) described below. That is, the powder removed during classification may be reused in the melt kneading in step (1) as a mixture containing toner powder and silica. The powder removed during classification includes the powder removed by upper limit classification (coarse powder) and the powder removed by lower limit classification (fine powder). From the viewpoint of production efficiency, in the present invention, it is preferable to use the fine powder as a mixture containing toner powder and silica.

[0096] The volume median diameter (D 50 ) of the mixture containing toner powder and silica is preferably 2 μm or more, more preferably 3 μm or more, still more preferably 3.5 μm or more, and preferably 8 μm or less, more preferably 6 μm or less, still more preferably 5 μm or less from the viewpoint of productivity.

[0097] The amount of the mixture containing toner powder and silica used in the toner mother particles is desirably such that the content of the mixture is preferably 5% by mass or more, more preferably 8% by mass or more, still more preferably 10% by mass or more, and preferably 25% by mass or less, more preferably 20% by mass or less, still more preferably 15% by mass or less.

[0098] In step (1), examples of the raw materials that can be subjected to melt kneading together with the binder resin and the mixture containing toner powder and silica include colorants, release agents, charge control agents, magnetic powders, fluidity improvers, conductivity adjusters, reinforcing fillers such as fibrous substances, antioxidants, and additives such as cleaning property improvers.

[0099] As the colorant, dyes, pigments, magnetic materials, etc. that are used as colorants for toner can be used. For example, carbon black, phthalocyanine blue, permanent brown FG, brilliant fast scarlet, pigment green B, rhodamine-B base, solvent red 49, solvent red 146, solvent blue 35, quinacridone, carmine 6B, isoindoline, disazo yellow, etc. may be mentioned. In the present invention, the toner may be either a black toner or a color toner.

[0100] From the viewpoint of improving the image density and low-temperature fixability of the toner, the amount of the colorant used is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and preferably 40 parts by mass or less, more preferably 20 parts by mass or less, still more preferably 10 parts by mass or less, based on 100 parts by mass of the binder resin.

[0101] As the release agent, 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. may be mentioned, and these can be used alone or in combination of two or more.

[0102] 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, still more preferably 110°C or lower.

[0103] The amount 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, from the viewpoints of low-temperature fixability and offset resistance of the toner and dispersibility in the binder resin.

[0104] The charge control agent is not particularly limited, and may contain either a positively chargeable charge control agent or a negatively chargeable charge control agent.

[0105] Examples of the positively chargeable 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" (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.).

[0106] In addition, examples of the negatively chargeable charge control agent include metal-containing azo dyes such as "Vari Fast Black 3804", "Bontron S-31", "Bontron S-32", "Bontron S-34", "Bontron S-36" (manufactured by Orient Chemical Industries, Ltd.), "Izen Spiron 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.

[0107] From the viewpoint of the charging stability of the toner, the amount of the charge control agent used 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, based on 100 parts by mass of the binder resin.

[0108] The mixture containing the binder resin, the toner powder, and silica, and if necessary, internal additives such as a colorant may be kneaded all at once or separately, but it is preferable to mix them in a mixer such as a Henschel mixer or a ball mill in advance and then supply them for melt-kneading.

[0109] In the present invention, an open roll type kneader capable of physically providing a high kneading share is used for melt-kneading.

[0110] An open roll type kneader refers to a kneading section that is not sealed but open, and can easily dissipate the kneading heat generated during melt kneading. The two-roll open roll type kneader used in the present invention is equipped with two rolls and has a raw material supply port and a kneaded product discharge port provided along the axial direction of the rolls. From the perspective of production efficiency, it is preferably a continuous two-roll open roll type kneader.

[0111] The two-roll open roll type kneader used in the present invention is preferably a kneader equipped with two rolls having different peripheral speeds, that is, 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 perspective 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.

[0112] The temperature of the roll can be adjusted, for example, by the temperature of the heat medium passed through the inside of the roll. For each roll, the inside of the roll may be divided into two or more parts and heat media with different temperatures may be passed through.

[0113] From the perspective 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 perspective, 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.

[0114] Both the high-speed roll and the low-speed roll preferably have a higher temperature on the raw material input side than on the kneaded material discharge side. The temperature difference between the raw material input side and the kneaded material 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, from the viewpoints of preventing the kneaded material from detaching from the roll, reducing the mechanical force during melt kneading, and suppressing heat generation.

[0115] The temperature on 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 on the kneaded material discharge side refers to the set temperature at the end of the kneaded material discharge side, respectively.

[0116] From the viewpoints of reducing the mechanical force during kneading and suppressing heat generation, 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 viewpoints, 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.

[0117] In addition, 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.

[0118] After step (1), the obtained kneaded material is appropriately cooled until it reaches a hardness that can be pulverized, and then subjected to the subsequent step (2). Here, cooling means cooling the kneaded material to 0°C to 50°C, or cooling it to below the glass transition temperature of the binder resin in the kneaded material.

[0119] Step (2) is a step of pulverizing and classifying the kneaded product obtained in step (1) to obtain toner mother particles.

[0120] In the pulverization of the kneaded product, the kneaded product may be pulverized at once to a desired particle size or pulverized step by step. However, from the viewpoints of efficient and more uniform pulverization, it is preferable to perform the pulverization in two steps of coarse pulverization and fine pulverization.

[0121] Examples of the pulverizer used for coarse pulverization include a hammer mill, a cutter mill, an atomizer, a rotorplex, etc.

[0122] In coarse pulverization, after appropriately coarsely pulverizing the kneaded product until the particle size becomes about 0.1 to 3 mm, it is passed through a sieve with an opening of about 2 to 3 mm, and the pulverized product passing through the sieve is preferably used for fine pulverization as a pulverized product with a maximum diameter of 2 to 3 mm or less.

[0123] 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.

[0124] The degree of fine pulverization is preferably adjusted as appropriate according to the particle size of the target toner mother particles.

[0125] Examples of the classifier used for classification include an air classifier, an inertial classifier, a sieve classifier, etc. During the classification step, the pulverized product that was not sufficiently pulverized and removed may be returned to the pulverization step, and the pulverization step and the classification step may be repeated as necessary.

[0126] In order to adjust the silica content in the toner mother particles, in step (2), the pulverization of the kneaded product may be performed in the presence of silica. In that case, it is preferable to perform fine pulverization and / or classification in the presence of silica.

[0127] The silica used in step (2) is the same as that described as the silica contained in the mixture used in step (1), and may be the same as or different from the silica contained in the mixture used in step (1), but it is preferably the same.

[0128] From the perspective of durability under high temperature and high humidity, the silica content in the toner mother particles obtained in step (2) is 0.8% by mass or more, preferably 2% by mass or more, more preferably 4% by mass or more, and from the perspective of dispersibility in the toner mother particles, it is 15% by mass or less, preferably 13% by mass or less, more preferably 11% by mass or less.

[0129] The volume median diameter (D 50 ) of the toner mother particles is preferably 3 μm or more, more preferably 4 μm or more, and preferably 15 μm or less, more preferably 10 μm or less. In this specification, the volume median 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.

[0130] The toner mother particles obtained in step (2) can be used as the toner as they are, but in the present invention, from the perspective of improving transferability, it is preferable to perform step (3) of mixing the toner mother particles obtained in step (2) with an external additive.

[0131] Examples of the external additive include inorganic fine particles such as silica, alumina, titania, zirconia, tin oxide, and 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 perspective of the transferability of the toner, hydrophobized hydrophobic silica is more preferable.

[0132] Examples of the hydrophobizing agent for hydrophobizing the surface of silica particles include hexamethyldisilazane (HMDS), dimethyldichlorosilane (DMDS), cyclic silazane, silicone oil, aminosilane, octyltriethoxysilane (OTES), and methyltriethoxysilane.

[0133] The number 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, from the viewpoints of the chargeability, fluidity, and transferability of the toner.

[0134] The mixing of the toner mother particles and the external additive can be carried out according to a conventional method, and a mixer such as a Henschel mixer can be used.

[0135] The amount of the external additive used 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, and preferably 5 parts by mass or less, more preferably 3 parts by mass or less, based on 100 parts by mass of the toner mother particles, from the viewpoints of the chargeability, fluidity, and transferability of the toner.

[0136] The toner obtained by the method of the present invention can be used as a one-component developer toner as it is, or as a two-component developer toner mixed with a carrier, in an image forming apparatus using a one-component development system or a two-component development system, respectively.

Examples

[0137] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. The physical properties of the resin and the like were measured by the following methods.

[0138] 〔Softening point of resin〕 Using a flow tester "CFT-500D" (manufactured by Shimadzu Corporation), while heating 1 g of the sample at a heating rate of 6 °C / min, a load of 1.96 MPa is applied by a plunger and extruded from a nozzle having a diameter of 1 mm and a length of 1 mm. The plunger drop amount of the flow tester is plotted against the temperature, and the temperature at which half of the sample flows out is taken as the softening point.

[0139] 〔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 cooling rate of 10°C / min, and maintain it at 0°C for 1 minute. Then, measure it at a heating rate of 10°C / min. Among the observed endothermic peaks, the temperature of the peak with the largest peak area is taken as the maximum endothermic peak temperature. For crystalline resins, the maximum endothermic peak temperature is taken as the melting point.

[0140] 〔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 cooling rate of 10°C / min. Next, heat the sample at a heating rate of 10°C / min and measure the endothermic peak. The temperature of the intersection of the extension line of the baseline below the maximum endothermic peak temperature and the tangent line showing the maximum slope from the rising part of the peak to the apex of the peak is taken as the glass transition temperature.

[0141] 〔Acid value of resin〕 Measure according to the method of JIS K 0070:1992. However, for the measuring 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 a mixed solvent of chloroform and dimethylformamide (chloroform:dimethylformamide = 7:3 (volume ratio)) for crystalline resins, respectively.

[0142] 〔Melting point of release agent〕 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 at a heating rate of 10°C / min, and then cool it from that temperature to -10°C at a cooling rate of 5°C / min. Next, heat the sample at a heating rate of 10°C / min up to 180°C, measure the heat quantity, and take the maximum endothermic peak temperature as the melting point.

[0143] 〔BET specific surface area of silica〕 Measure by the nitrogen adsorption method under the following conditions. · Measuring device: Specific surface area measuring device "Micromeritics FlowSorbIII" (manufactured by Shimadzu Corporation) · Sample amount: 0.04 - 0.08 g · Degassing conditions: 40 °C, 10 minutes · Adsorbed gas: Nitrogen gas

[0144] 〔Number average particle diameter of silica and external additive〕 Measure the particle diameters (average value of major axis and minor axis) of 500 particles from a scanning electron microscope (SEM) photograph, and use their number average value.

[0145] 〔Volume median diameter (D 50 ) of the mixture containing toner powder and silica and toner mother particles〕 · 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 above 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 electrolyte, and further disperse it for 1 minute with the ultrasonic disperser to prepare a sample dispersion liquid. · Measurement conditions: After adjusting the concentration so that the particle diameters of 30,000 particles can be measured in 20 seconds by adding the above sample dispersion liquid to 100 mL of the electrolyte, measure 30,000 particles, and obtain the volume median diameter (D 50 ) from the particle size distribution.

[0146] Resin production example 1 The raw material monomers, esterification catalysts, and polymerization inhibitors of the polyester resin other than trimellitic anhydride shown in Table 1 were placed in a 10-liter four-necked flask equipped with a water removal tube with a nitrogen introduction tube, a stirrer, and a thermocouple, and heated to 210°C in a mantle heater under a nitrogen atmosphere, followed by polycondensation for 7 hours. Thereafter, the temperature was lowered to 200°C, trimellitic anhydride was added, and then the temperature was raised to 210°C, and a polycondensation reaction was carried out until the softening point shown in Table 1 was reached to obtain an amorphous polyester resin (Resin A1). The physical properties of the obtained resin are shown in Table 1.

[0147] Resin Production Example 2 The raw material monomers of the polyester resin other than trimellitic anhydride shown in Table 1 and the esterification catalyst were placed in a 10-liter four-necked flask equipped with a water removal tube 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 of the styrene resin, both reactive monomers, and a polymerization initiator was dropped by a dropping funnel over 1 hour to carry out polymerization. Thereafter, the temperature was raised to 200°C and aged for 1 hour to generate 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 dehydrative 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 reaction was carried out at 8 kPa until the softening point shown in Table 1 was reached to obtain an amorphous composite resin (Resin A2). The physical properties of the obtained resin are shown in Table 1.

[0148]

Table 1

[0149] Resin Production Example 3 The alcohol component, carboxylic acid component, and esterification catalyst shown in Table 2 were placed in a 10-liter four-necked flask equipped with a nitrogen inlet tube, a dehydrating tube, a stirrer, and a thermocouple, and heated in a mantle heater under a nitrogen atmosphere to 200 °C over 8 hours. Thereafter, the reaction was carried out at 8 kPa until the softening point shown in Table 2 was reached, and crystalline polyester resins (Resins C1, C2, and C4) were obtained. The physical properties of the obtained resins are shown in Table 2.

[0150] Production Example 4 of Resin The alcohol component, carboxylic acid component, esterification catalyst, and polymerization inhibitor shown in Table 2 were placed in a 10-liter four-necked flask equipped with a nitrogen inlet tube, a dehydrating tube, a stirrer, and a thermocouple, and heated in a mantle heater under a nitrogen atmosphere to 200 °C over 8 hours. Thereafter, the reaction was carried out at 8 kPa until the softening point shown in Table 2 was reached, and a crystalline polyester resin (Resin C3) was obtained. The physical properties of the obtained resin are shown in Table 2.

[0151] [Table 2]

[0152] Production Example 1 of Mixture of Toner Powder and Silica 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 3, 5 parts by mass of a colorant "ECB-301" (manufactured by Dainichi Seika Kogyo Co., Ltd., phthalocyanine blue (P.B.15:3)), 4 parts by mass of a mold release agent "HNP-9" (manufactured by Nippon Seiro Co., Ltd., paraffin wax, melting point: 80 °C), and 0.5 parts by mass of a 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 following conditions using a continuous two-open roll kneader "Neidex" (manufactured by Nippon Coke & Engineering Co., Ltd., roll outer diameter: 14 cm, effective roll length: 80 cm).

[0153] The operating conditions of the continuous twin open-roll kneader were as follows: the peripheral speed of the high-speed roll (front roll) was 32.4 m / min, the peripheral speed of the low-speed roll (back roll) was 21.7 m / min, and the roll gap was 0.1 mm. The temperature of the heating medium and the cooling medium inside the rolls were as follows: on the raw material input side of the high-speed roll, it was 145 °C, and on the kneaded product discharge side, it was 100 °C; on the raw material input side of the low-speed roll, it was 75 °C, and on the kneaded product discharge side, it was 35 °C. Also, the supply rate of the raw material mixture was 10 kg / h, and the average residence time was about 3 minutes.

[0154] 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 volume median diameter of 2 mm or less was obtained using a sieve with an aperture of 2 mm. To the obtained roughly pulverized product, 1.1 parts by mass of silica "R972" (manufactured by Nippon Aerosil Co., Ltd., hydrophobic silica, hydrophobizing agent: DMDS, number average particle diameter: 16 nm, BET specific surface area: 130 m 2 / g) (an amount such that the content of silica in the mixture was 1% by mass) was mixed, and fine pulverization and classification were performed using an impact plate type jet mill "IDS-2 type" (manufactured by Nippon Pneumatic Mfg. Co., Ltd.) and an air classifier "DS-2 type" (manufactured by Nippon Pneumatic Mfg. Co., Ltd.) so that the volume median diameter (D 50 ) became 4.2 μm, and a mixture of toner powder and silica (mixture 1) was obtained.

[0155] Production Example 2 of a mixture containing toner powder and silica A mixture of toner powder and silica (mixtures 2 to 7, 10) was obtained in the same manner as in Production Example 1, except that the type of crystalline polyester resin and the amount of silica used for mixing with the roughly pulverized product were changed as shown in Table 3.

[0156] Production Example 3 of a mixture containing toner powder and silica A mixture of toner powder and silica (mixture 8) was obtained in the same manner as in mixture 3, except that "R976" (hydrophobic silica, manufactured by Nippon Aerosil Co., Ltd., number average particle diameter: 8 nm, hydrophobizing agent: DMDS, BET specific surface area: 300 m 2 / g) was used instead of "R972".

[0157] Production Example 4 of Mixture Containing Toner Powder and Silica A mixture of toner powder and silica (Mixture 9) was obtained in the same manner as Mixture 3, except that "RX50" (hydrophobic silica, manufactured by Nippon Aerosil Co., Ltd., hydrophobizing agent: HMDS, number average particle diameter: 40 nm, BET specific surface area: 50 m 2 / g) was used instead of "R972".

[0158] Production Example 5 of Mixture Containing Toner Powder and Silica A mixture of toner powder and silica (Mixture 11) was obtained in the same manner as Mixture 3, except that a twin-screw extruder was used instead of the continuous two-open-roll kneader in the melt-kneading step. 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.

[0159] Production Example 6 of Mixture of Toner Powder and Silica 40 parts by mass of Resin A1, 40 parts by mass of Resin A2, 20 parts by mass of Resin C1, 5 parts by mass of colorant "ECB-301" (manufactured by Dainichi Seika Kogyo Co., Ltd., phthalocyanine blue (P.B.15:3)), 4 parts by mass of mold release agent "HNP-9" (manufactured by Nippon Seiro Co., Ltd., paraffin wax, melting point: 80 °C), and 0.5 parts by mass of 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 using a continuous two-open-roll kneader "Neutex" (manufactured by Nippon Coke & Engineering Co., Ltd., roll outer diameter: 14 cm, effective roll length: 80 cm).

[0160] The operating conditions of the continuous twin open roll kneader were as follows: the peripheral speed of the high-speed roll (front roll) was 32.4 m / min, the peripheral speed of the low-speed roll (back roll) was 21.7 m / min, and the roll gap was 0.1 mm. The temperature of the heating medium and the cooling medium inside the rolls 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.

[0161] The obtained kneaded product was cooled and roughly pulverized by a crusher "Rotoplex" (manufactured by Hosokawa Micron Corporation), and a roughly pulverized product with a volume median diameter of 2 mm or less was obtained using a sieve with an opening of 2 mm. To the obtained roughly pulverized product, 5.8 parts by mass of silica "R972" (manufactured by Nippon Aerosil Co., Ltd., hydrophobic silica, hydrophobizing agent: DMDS, number average particle diameter: 16 nm, BET specific surface area: 130 m 2 / g) (the amount such that the content of silica becomes 5% by mass in the mixture) was mixed, and fine pulverization and classification were performed using an impact plate type jet mill "IDS-2 type" (manufactured by Nippon Pneumatic Mfg. Co., Ltd.) and an air classifier "DS-2 type" (manufactured by Nippon Pneumatic Mfg. Co., Ltd.) so that the volume median diameter (D 50 ) became 6.0 μm. At this time, the powder on the fine powder side obtained by classification was recovered to obtain a mixture of toner powder and silica (mixture 12). The volume median diameter (D 50 ) of the mixture was 4.1 μm.

[0162] Production Example 7 of Mixture of Toner Powder and Silica As a colorant, instead of "ECB-301" (manufactured by Dainichi Seika Kogyo Co., Ltd., phthalocyanine blue (P.B.15:3)), 5 parts by mass of "Mogul-L" (manufactured by Cabot Corporation, carbon black) was used, and in the same manner as mixture 12, a mixture of toner powder and silica (mixture 13) was obtained. The volume median diameter (D 50 ) of the mixture was 4.1 μm.

[0163] Production Example 8 of Mixture of Toner Powder and Silica As a colorant, except that 5 parts by mass of "FASTOGEN SUPER MAGENTA R3-E" (manufactured by DIC Corporation, quinacridone-based pigment (P.R.122)) was used instead of "ECB-301" (manufactured by Dainichi Seika Kogyo Co., Ltd., phthalocyanine blue (P.B.15:3)), a mixture of toner powder and silica (mixture 14) was obtained in the same manner as mixture 12. The volume median diameter (D 50 ) of the mixture was 4.1 μm.

[0164] Production Example 9 of Mixture of Toner Powder and Silica As a colorant, except that 5 parts by mass of "PARIO FAST YELLOW D1155" (manufactured by Sankyo Chemical Co., Ltd. (P.Y.185)) was used instead of "ECB-301" (manufactured by Dainichi Seika Kogyo Co., Ltd., phthalocyanine blue (P.B.15:3)), a mixture of toner powder and silica (mixture 15) was obtained in the same manner as mixture 12. The volume median diameter (D 50 ) of the mixture was 4.1 μm.

[0165]

Table 3

[0166] 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, 5 parts by mass of the colorant "ECB-301" (manufactured by Dainichi Seika Kogyo Co., Ltd., phthalocyanine blue (P.B.15:3)), 4 parts by mass of the release agent "HNP-9" (manufactured by Nippon Seiro Co., Ltd., paraffin wax, melting point: 80°C), 0.5 parts by mass of the charge control agent "Bontron E-304" (manufactured by Orient Chemical Industries Co., Ltd.), and 15 parts by mass of the mixture of toner powder and silica shown in Table 4 were thoroughly mixed with a Henschel mixer, and then melt-kneaded under the following conditions using a continuous two-open roll type kneader "Neutex" (manufactured by Nippon Coke & Engineering Co., Ltd., roll outer diameter: 14 cm, effective roll length: 80 cm).

[0167] The operating conditions of the continuous two-open roll kneader were as follows: the peripheral speed of the high-speed roll (front roll) was 32.4 m / min, the peripheral speed of the low-speed roll (back roll) was 21.7 m / min, and the roll gap was 0.1 mm. The temperature of the heating medium and the cooling medium inside the roll were as follows: on the raw material input side of the high-speed roll, it was 145 °C, and on the kneaded product discharge side, it was 100 °C; on the raw material input side of the low-speed roll, it was 75 °C, and on the kneaded product discharge side, it was 35 °C. Also, the supply rate of the raw material mixture was 10 kg / hr, and the average residence time was about 3 minutes.

[0168] The obtained kneaded product was cooled and roughly pulverized by a crusher "Rotoplex" (manufactured by Hosokawa Micron Corporation), and a roughly pulverized product with a volume median particle diameter of 2 mm or less was obtained using a sieve with an opening of 2 mm. To the obtained roughly pulverized product, 1.1 parts by mass of silica "R972" (hydrophobic silica, manufactured by Nippon Aerosil Co., Ltd., hydrophobizing agent: DMDS, number average particle diameter: 16 nm, BET specific surface area: 130 m 2 / g) (the amount such that the content of silica becomes 1% by mass in the toner mother particles) was mixed, and fine pulverization and classification were performed using an impact plate jet mill "IDS-2 type" (manufactured by Nippon Pneumatic Mfg. Co., Ltd.) and an air classifier "DS-2 type" (manufactured by Nippon Pneumatic Mfg. Co., Ltd.) so that the volume median particle diameter (D 50 ) became 6.0 μm, and toner mother particles were obtained.

[0169] To 100 parts by mass of the obtained toner mother particles, 1.0 part by mass of hydrophobic silica "R972" (manufactured by Nippon Aerosil Co., Ltd., hydrophobizing agent: DMDS, number average particle diameter: 16 nm, BET specific surface area: 130 m 2 / g) and 1.0 part by mass of "RX50" (hydrophobic silica, manufactured by Nippon Aerosil Co., Ltd., hydrophobizing agent: HMDS, number average particle diameter: 40 nm) were added as external additives, and using a Henschel mixer, mixing was performed at 3700 r / min for 3 minutes to perform external additive treatment, and toner was obtained.

[0170] Examples 2 to 7, 10, and Comparative Example 1 A toner was obtained in the same manner as in Example 1, except that the type of crystalline polyester resin, the type of the mixture of toner powder and silica, and the amount of silica used for mixing with the coarsely pulverized material were changed as shown in Table 4.

[0171] Example 8 A toner was obtained in the same manner as in Example 3, except that mixture 8 was used instead of mixture 3, and "R976" (hydrophobic silica, manufactured by Nippon Aerosil Co., Ltd., hydrophobizing agent: DMDS, number average particle diameter: 8 nm, BET specific surface area: 300 m 2 / g) was used instead of "R972".

[0172] Example 9 A toner was obtained in the same manner as in Example 3, except that mixture 9 was used instead of mixture 3, and "RX50" (hydrophobic silica, manufactured by Nippon Aerosil Co., Ltd., hydrophobizing agent: HMDS, number average particle diameter: 40 nm, BET specific surface area: 50 m 2 / g) was used instead of "R972".

[0173] Example 11 A toner was obtained in the same manner as in Example 3, except that mixture 13 was used instead of mixture 3, and "Mogul-L" (carbon black, manufactured by Cabot Corporation) was used as the colorant instead of "ECB-301" (phthalocyanine blue (P.B.15:3), manufactured by Dainichi Seika Kogyo Co., Ltd.).

[0174] Example 12 A toner was obtained in the same manner as in Example 3, except that mixture 14 was used instead of mixture 3, and "FASTOGEN SUPER MAGENTA R3-E" (quinacridone-based pigment (P.R.122), manufactured by DIC Corporation) was used as the colorant instead of "ECB-301" (phthalocyanine blue (P.B.15:3), manufactured by Dainichi Seika Kogyo Co., Ltd.).

[0175] Example 13 Instead of mixture 3, toner was obtained in the same manner as in Example 3, except that mixture 15 was used, and instead of "ECB-301" (manufactured by Dainichi Seika Kogyo Co., Ltd., phthalocyanine blue (P.B.15:3)) as the colorant, "Pario Tol Yellow D1155" (manufactured by Sankyo Chemical Co., Ltd. (P.Y.185)) was used respectively.

[0176] Comparative Example 2 Toner was obtained in the same manner as in Example 3, except that mixture 3 was not used.

[0177] Comparative Example 3 Toner was obtained in the same manner as in Example 3, except that 0.66 part by mass of hydrophobic silica "R972" was used instead of mixture 3, and the amount of silica used for mixing with the coarse pulverized product was changed to 5.1 parts by mass (the amount at which the silica content becomes 5% by mass in the toner mother particles).

[0178] Comparative Example 4 Toner was obtained in the same manner as in Example 3, except that mixture 11 was used instead of mixture 3, and in the melt kneading process, a twin-screw extruder was used instead of a continuous two-open roll type kneader. The operating conditions of the twin-screw extruder were a barrel set temperature of 100°C, a shaft rotation speed of 200 r / min (the peripheral speed of the shaft rotation was 0.30 m / sec), and a mixture supply rate of 10 kg / h.

[0179] Test Example [Durability] The toner cartridge of the non-magnetic one-component developing device "COREFIDO C844dnw" (manufactured by Okidata Corporation) was loaded into an idling machine that can be driven by an external motor, adjusted to a printing speed equivalent to 45 sheets / min in the A4 paper horizontal feed conversion, and the toner was installed. In a high-temperature and high-humidity environment (32.5°C, 80% RH), the idling machine was continuously operated, and the occurrence status of streaks on the surface of the developing roller was visually observed every 0.5 hours. The maximum time without the occurrence of streaks was evaluated as the durability. The results are shown in Table 4.

[0180]

Table 4

[0181] From the above results, it can be seen that in Examples 1 to 13, toners with good durability under high temperature and high humidity are obtained. On the other hand, in Comparative Examples 1 and 2 where silica is not internally added to the toner particles or the amount is insufficient even if it is added, and in Comparative Example 3 where silica is internally added directly to the toner particles instead of being mixed with the toner powder, the durability is insufficient. Further, in Comparative Example 4 where a twin-screw extruder is used instead of an open roll kneader in the melt-kneading process, the deterioration of durability is more remarkable.

Industrial Applicability

[0182] The electrostatic charge image developing toner obtained by the method of the present invention is suitably used for developing latent images formed in electrostatic charge image developing methods, electrostatic recording methods, electrostatic printing methods, etc.

Claims

1. A method for producing a toner for developing electrostatic images, comprising: a step (1) of melting and kneading a mixture containing at least a binder resin, a toner powder, and silica using an open roll type kneader; and a step (2) of pulverizing and classifying the kneaded product obtained in the step (1) to obtain toner base particles, wherein the binder resin contains a crystalline polyester resin C, and the content of silica in the toner base particles is 0.8% by mass or more and 15% by mass or less.

2. 2. The method for producing a toner for developing electrostatic images according to claim 1, wherein in the step (2), the kneaded mixture is pulverized in the presence of silica.

3. 3. The method for producing a toner for developing electrostatic images according to claim 1, wherein the mixture containing a powder for a toner and silica is a mixture obtained by a method including the steps of melt-kneading a mixture containing a crystalline polyester resin C' using an open roll type kneader, and pulverizing the obtained kneaded mixture in the presence of silica.

4. 3. The method for producing a toner for developing electrostatic images according to claim 1, wherein the mixture containing a powder for a toner and silica is a powder removed by lower limit classification during classification in the step (2).

5. 3. The method for producing a toner for developing electrostatic images according to claim 1, wherein the amount of the mixture containing the powder for a toner and silica is such that the content of the mixture in the toner base particles is 5% by mass or more and 25% by mass or less.

6. The BET specific surface area of ​​silica is 10 m ２ / g or more 350m ２ 3. The method for producing a toner for developing electrostatic images according to claim 1, wherein the toner has a molecular weight of 1 / g or less.

7. 3. The method for producing a toner for developing electrostatic images according to claim 1, wherein the content of the crystalline polyester resin C in the binder resin is from 5% by mass to 35% by mass.

8. 3. The method for producing a toner for developing an electrostatic image according to claim 1, further comprising a step (3) of mixing the toner base particles obtained in the step (2) with an external additive.

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