JP2023085816A - Manufacturing method of electrostatic charge image development toner - Google Patents

Abstract

To provide a manufacturing method of electrostatic charge development toner capable of achieving thin line reproducibility.SOLUTION: There is provided a manufacturing method of electrostatic charge image development toner which includes: toner base particles each containing binder resin and coloring agent; and external additive containing inorganic particles A having number average particle diameter of 60 nm or more and 100 nm or less and reversely charged polarity with respect to the toner base particles and inorganic particles B having number average particle diameter of 30 nm or more and 60 nm or less and equally charged polarity with respect to the toner base particle. The manufacturing method includes: a step A of mixing the toner base particle into 3.2 parts by mass or more and 4.8 parts by mass or less of the inorganic particle A to the toner base particle 100 parts by mass, and externally adding the inorganic particle A in the toner base particle; and a step B of mixing the toner base particle into 0.2 parts by mass or more and 1.7 parts by mass or less of the inorganic particle B to the toner base particle 100 parts by mass, and externally adding the inorganic particle B in the toner base particle.SELECTED DRAWING: None

Description

The present invention relates to a method for producing an electrostatic charge image developing toner used for developing a latent image formed in an electrophotography method, an electrostatic recording method, an electrostatic printing method, or the like.

In recent years, as the speed of printers has increased, the demand for toner performance has increased, and external additive formulations have been devised in order to stabilize charging stability and improve fluidity of toner.

For example, in Patent Document 1, after the step of adding and stirring an external additive that weakens the polarity of the toner base particles, an external additive that strengthens the polarity of the toner base particles is added and stirred, whereby even in continuous printing, It is described that the occurrence of fogging and streaks can be reduced and good developability can be maintained.

Further, in Patent Document 2, as a first step, negatively charged hydrophobic silica fine particles are externally added to positively charged toner base particles, and as a second step, positively charged hydrophobic silica fine particles A having a large specific surface area are added. Non-magnetic electrostatic image development is said to be free from problems such as the occurrence of so-called fogging by adding the positively charged hydrophobic silica fine particles B, which have a small specific surface area, in the third step. A method of making a toner for a printer is described.

Furthermore, Patent Document 3 discloses a method in which an external additive having the same charging polarity is added to toner base particles, and then an external additive having opposite charging polarity is added. On the other hand, it describes a method of simultaneously adding external additives having the same charging polarity and the opposite charging polarity, and is described as being able to improve the charging stability of the toner.

Japanese Patent Application Laid-Open No. 2008-40160 JP 2013-122499 A Japanese Patent Application Laid-Open No. 2004-240127 JP 2015-4929 A

However, the conventional methods are still insufficient in fine line reproducibility, and there is room for improvement.

TECHNICAL FIELD The present invention relates to a method for producing a toner for electrostatic charge development capable of obtaining good fine line reproducibility.

The present invention comprises toner base particles containing a binder resin and a colorant, inorganic particles A having a number average particle diameter of 60 nm or more and 100 nm or less and having a reverse charge polarity with respect to the toner base particles, and a number average particle diameter of A method for producing a toner for developing an electrostatic charge image, comprising:
A step A of mixing the toner base particles and 3.2 parts by mass or more and 4.8 parts by weight or less of inorganic particles A with respect to 100 parts by weight of the toner base particles, and externally adding the inorganic particles A to the toner base particles; Step B of mixing the mother particles and 0.2 parts by mass or more and 1.7 parts by mass or less of the inorganic particles B with respect to 100 parts by mass of the toner mother particles, and externally adding the inorganic particles B to the toner mother particles.
and a method for producing a toner for developing an electrostatic charge image.

The electrostatic charge image developing toner obtained by the method of the present invention can achieve good fine line reproducibility.

According to the present invention, when the toner base particles are externally added, predetermined amounts of inorganic particles A and B each having a predetermined particle size and having different charging polarities are externally added to the toner base particles separately. This is a method for obtaining a toner, and although the details are unknown, it is presumed that the effects of the present invention are exhibited by the following mechanism.

The inorganic particles A are an external additive with a relatively large particle size. An external additive having a large particle size is effective in imparting fluidity, but has the drawback of being difficult to adhere to toner base particles. However, since the inorganic particles A have a charge polarity opposite to that of the toner base particles, they can be efficiently attached to the toner base particles using electrostatic attraction. On the other hand, an external additive with small particles is effective in imparting chargeability, but has the disadvantage of being prone to agglomeration. However, in the present invention, by using the inorganic particles B, which are smaller than the inorganic particles A and have a larger particle size than the external additives widely used in toners, aggregation can be prevented while maintaining chargeability. can be suppressed. In addition, since the inorganic particles B adhere to the exposed surfaces of the toner base particles to which the inorganic particles A do not adhere, the surfaces of the toner base particles can be efficiently coated. This improves the fluidity of the toner and evenly charges the toner particles when they are triboelectrically charged in the cartridge. It is considered that good fine line reproducibility can be achieved.

The toner base particles contain a binder resin and a colorant.

Examples of binder resins include polyester resins, vinyl resins such as styrene-acrylic resins, epoxy resins, polycarbonates, polyurethanes, and composite resins containing two or more of these resins. From the viewpoint of production stability, it preferably contains a polyester resin, and more preferably contains an amorphous polyester resin.

The amorphous polyester resin is preferably a polycondensate of an alcohol component containing an alkylene oxide adduct of bisphenol A and a carboxylic acid component.

The alkylene oxide adduct of bisphenol A has the formula (I):

(Wherein, OR and RO are oxyalkylene groups, R is an ethylene group and/or propylene group, x and y represent the average number of added moles of alkylene oxide, each being a positive number, and 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 still more preferably 4 or less)
A compound represented by is preferred.

From the viewpoint of low-temperature fixability, the content of the alkylene oxide adduct of bisphenol A is preferably 70 mol% or more, more preferably 80 mol% or more, still more preferably 90 mol% or more, still more preferably 95 mol% or more, in the alcohol component. mol % or more, more preferably 100 mol %.

Other alcohol components include trihydric or higher alcohols such as aliphatic diols, bisphenol A, hydrogenated bisphenol A, sorbitol, pentaerythritol, glycerin, and trimethylolpropane.

Examples of the carboxylic acid component include aromatic dicarboxylic acid-based compounds, aliphatic dicarboxylic acid-based compounds, and trivalent or higher carboxylic acid-based compounds.

Examples of 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.

From the viewpoint of image density, the carboxylic acid component preferably contains an aromatic dicarboxylic acid compound. The content of the aromatic dicarboxylic acid compound in the carboxylic acid component is preferably 20 mol% or more, more preferably 35 mol% or more, and still more preferably 50 mol% or more. It is 100 mol % or less, preferably 90 mol % or less, more preferably 80 mol % or less.

Aliphatic dicarboxylic acid compounds include fumaric acid, maleic acid, succinic acid, hydrocarbon-substituted succinic acid derivatives, glutaric acid, adipic acid, sebacic acid, anhydrides of these acids, and carbon atoms of these acids. Examples thereof include alkyl esters having a number of 1 or more and 3 or less.

Trivalent or higher carboxylic acid compounds include trimellitic acid, pyromellitic acid, anhydrides of these acids, alkyl esters of these acids having 1 to 3 carbon atoms, and the like.

The alcohol component may contain a monohydric alcohol, and the carboxylic acid component may contain a monovalent carboxylic acid-based compound, as appropriate.

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 0.6 or more, more preferably 0.7 or more, and still more preferably 0.75 from the viewpoint of adjusting the softening point of the polyester resin. and preferably 1.2 or less, more preferably 1.15 or less.

The amorphous polyester resin can be produced, for example, by mixing an alcohol component and a carboxylic acid component, which are raw material monomers, in an inert gas atmosphere, preferably in the presence of an esterification catalyst, and if necessary, an esterification co-catalyst and a polymerization inhibitor. etc., preferably at a temperature of 130° C. or higher, more preferably 170° C. or higher, and preferably 250° C. or lower, more preferably 240° C. or lower.

Examples of the esterification catalyst include tin compounds such as dibutyltin oxide and tin(II) 2-ethylhexanoate, and titanium compounds such as titanium diisopropylate bistriethanolamine, and tin compounds are preferred. The amount of the esterification catalyst used is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, and preferably 1.5 parts by mass or less, more preferably 1 part by mass or less, relative to 100 parts by mass of the raw material monomer. is. Gallic acid etc. are mentioned as an esterification co-catalyst. The amount of the esterification promoter used is preferably 0.001 parts by mass or more, more preferably 0.01 parts by mass or more, and preferably 0.5 parts by mass or less, more preferably 0.1 parts by mass, relative to 100 parts by mass of the raw material monomer. It is below. Polymerization inhibitors include tert-butyl catechol and the like. The amount of the polymerization inhibitor used is preferably 0.001 parts by mass or more, more preferably 0.01 parts by mass or more, and preferably 0.5 parts by mass or less, more preferably 0.1 parts by mass or less, relative to 100 parts by mass of the raw material monomer. is.

In addition, in the present invention, the polyester resin may be a polyester resin that has been modified to such an extent that its properties are not substantially impaired. Modified polyester resins include, for example, grafting or blocking 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, urethane-modified polyester resins obtained by urethane-extending a polyester resin with a polyisocyanate compound are preferred.

The softening point of the amorphous polyester resin is preferably 90° C. or higher, more preferably 100° C. or higher, and still more preferably 110° C. or higher from the viewpoint of hot offset resistance. is 160° C. or lower, more preferably 150° C. or lower, and still more preferably 140° C. or lower.

The crystallinity of the resin is represented by the ratio of the softening point to the maximum endothermic peak temperature measured by a differential scanning calorimeter, that is, the crystallinity index defined by the value of [softening point/maximum endothermic peak temperature]. The crystalline resin is a resin having a crystallinity index of 0.6 or more, preferably 0.7 or more, more preferably 0.9 or more, and 1.4 or less, preferably 1.2 or less, more preferably 1.1 or less.
On the other hand, the amorphous resin is a resin having a crystallinity index of greater than 1.4, preferably greater than 1.5, and more preferably greater than 1.6, or less than 0.6 when no endothermic peak is observed. , preferably 0.5 or less.
The crystallinity of the resin can be adjusted by the type and ratio of raw material monomers, production conditions (eg, reaction temperature, reaction time, cooling rate), and the like. The maximum endothermic peak temperature refers to the temperature of the peak with the maximum peak area among the observed endothermic peaks. In a crystalline resin, the maximum endothermic peak temperature is defined as the melting point.

The glass transition temperature of the amorphous polyester resin is preferably 40° C. or higher, more preferably 45° C. or higher, and still more preferably 50° C. or higher from the viewpoint of heat-resistant storage stability. is 75°C or lower, more preferably 70°C or lower, and even more preferably 65°C or lower.

The acid value of the amorphous polyester resin is preferably 1 mgKOH/g or more, more preferably 3 mgKOH/g or more, and preferably 40 mgKOH/g or less, more preferably 30 mgKOH/g or less, from the viewpoint of low-temperature fixability. is.

The content of the amorphous polyester resin in the binder resin is preferably 70% by mass or more, more preferably 80% by mass or more, from the viewpoint of durability, and 99% by mass from the viewpoint of low-temperature fixability. 98% by mass or less, more preferably 98% by mass or less.

From the viewpoint of low-temperature fixability, the binder resin preferably contains a crystalline polyester resin in addition to the amorphous polyester resin.

Examples of the crystalline polyester-based resin include a crystalline polyester resin, a crystalline composite resin containing a crystalline polyester resin and a styrene-based resin, and the like.

The crystalline polyester resin is preferably a polycondensate of an alcohol component containing an aliphatic diol and a carboxylic acid component.

Aliphatic diols include 1,4-butanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1, 11-undecanediol, 1,12-dodecanediol and the like.

The number of carbon atoms in the aliphatic diol is preferably 4 or more, more preferably 6 or more, from the viewpoint of low-temperature fixability. It is preferably 10 or less.

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-straight-chain alkanediol.

The alcohol component may contain an alcohol other than the aliphatic diol, but the content of the aliphatic diol in the alcohol component is preferably 70 mol% or more, more preferably 90 mol% or more, and still more preferably It is 95 mol % or more, more preferably 100 mol %.

Alcohol components other than aliphatic diols include aromatic diols such as alkylene oxide adducts of bisphenol A, trihydric or higher alcohols such as glycerin, and the like.

From the viewpoint of durability, the carboxylic acid component preferably contains an aromatic dicarboxylic acid-based compound.

Examples of 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. Acids are preferred.

The content of the aromatic dicarboxylic acid compound is preferably 70 mol% or more, more preferably 90 mol% or more, still more preferably 95 mol% or more, still more preferably 100 mol% of the carboxylic acid component.

Examples of carboxylic acid components other than aromatic dicarboxylic acid compounds include aliphatic dicarboxylic acid compounds and trivalent or higher carboxylic acid compounds.

The crystalline polyester resin can be produced by polycondensation of an alcohol and a carboxylic acid compound in the same manner as the amorphous polyester resin. The polycondensation reaction temperature is preferably 130° C. or higher, more preferably 140° C. or higher, and preferably 230° C. or lower, more preferably 220° C. or lower.

The crystalline composite resin preferably contains the crystalline polyester resin and the styrene resin.

Styrenic resins are addition polymers of raw material monomers containing at least styrene or styrene derivatives such as α-methylstyrene and vinyltoluene (hereinafter, styrene and styrene derivatives are collectively referred to as "styrene compounds").

The content of styrene compounds, preferably styrene, is preferably 70% by mass or more, more preferably 80% by mass or more, and still more preferably 90% by mass or more, in the raw material monomer of the styrene resin, from the viewpoint of durability and storage stability. , more preferably 95% by mass or more, more preferably 100% by mass.

Raw material monomers other than styrene compounds include (meth)acrylic acid alkyl esters; ethylenically unsaturated monoolefins such as ethylene and propylene; diolefins such as butadiene; halovinyls such as vinyl chloride; vinyl 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, etc. is mentioned.

The addition polymerization reaction of raw material monomers for styrene resins can be carried out by conventional methods, for example, in the presence of a polymerization initiator such as dicumyl peroxide, a polymerization inhibitor, a cross-linking agent, or the like, in the presence or absence of an organic solvent. However, the temperature conditions are preferably 110° C. or higher, more preferably 140° C. or higher, and preferably 200° C. or lower, more preferably 170° C. or lower.

When using an organic solvent for 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 monomer for the styrene resin.

More preferably, the composite resin is a resin chemically bonded by covalent bonds via a bi-reactive monomer capable of reacting with both the starting monomer for the polyester resin and the starting monomer for the styrenic resin.

Both reactive monomers have, in the molecule, 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, preferably a hydroxyl group and/or a carboxyl group. A compound having a group, more preferably a carboxy group, and an ethylenically unsaturated bond 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, At least one selected from the group consisting of acrylic acid, methacrylic acid and fumaric acid is more preferable, and acrylic acid is more preferable, from the viewpoint of reactivity in polycondensation reaction and addition polymerization reaction. However, when used together with a polymerization inhibitor, polyvalent carboxylic acid compounds having an ethylenically unsaturated bond such as fumaric acid function as raw material monomers for polyester resins. In this case, fumaric acid or the like is not a bireactive monomer but a starting monomer for the polyester resin.

From the viewpoint of low-temperature fixability, the amount of the bi-reactive monomer used is preferably 1 mol or more, more preferably 2 mol or more, and still more preferably 3 mol or more with respect to a total of 100 mol of the alcohol component of the polyester resin. From the viewpoint of enhancing the dispersibility of the styrene-based resin and the polyester resin and improving the durability of the toner, the amount is preferably 30 mol or less, more preferably 20 mol or less, and still more preferably 10 mol or less.
In addition, from the viewpoint of low-temperature fixability, the amount of the bi-reactive monomer used is preferably 1 part by mass or more, more preferably 2 parts by mass or more, relative to a total of 100 parts by mass of raw material monomers for the styrene resin. From the viewpoint of increasing the dispersibility of the styrene-based resin and the polyester resin and improving the durability of the toner, the amount is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less. Here, the total amount of raw material monomers for the styrene resin includes the polymerization initiator.

The composite resin can be produced, for example, by a method including a step (A) of polycondensation reaction using raw material monomers of the polyester resin and a step (B) of addition polymerization reaction using raw material monomers of the styrene resin. (i) step (B) may be performed after step (A); (ii) step (A) may be performed after step (B); (iii) step (A) and step (B ) may be performed at the same time. The bi-reactive monomer is preferably used together with the raw material monomer for the styrenic resin.

In the method (i), after the step (B), the reaction temperature is raised again, and if necessary, a raw material monomer for a trivalent or higher amorphous polyester resin as a cross-linking agent is added to the reaction system, and the step The polycondensation reaction of (A) and the reaction with the bireactive monomer may be further advanced.
Further, instead of the step (A) of conducting a polycondensation reaction, a prepolymerized polycondensation resin may be used. When the step (A) and the step (B) are carried out in parallel, the mixture containing the raw material monomers for the styrene-based resin may be added dropwise to the mixture containing the raw material monomers for the polyester resin to cause the reaction. .

Step (A) and step (B) are preferably carried out in the same container.

The mass ratio of the crystalline polyester resin to the styrene resin in the composite resin (crystalline polyester resin/styrene resin) is preferably 60/40 or more, more preferably 70/30 or more, from the viewpoint of low-temperature fixability. From the viewpoint of durability, it is preferably 97/3 or less, more preferably 93/7 or less, and even more preferably 90/10 or less. In the above calculation, the mass of the polyester resin is the amount obtained by subtracting the amount of reaction water dehydrated by the polycondensation reaction (calculated value) from the mass of the raw material monomer of the polyester resin used. The amount of is included in the raw material monomer amount of the polyester resin. Moreover, the amount of styrene resin is the total amount of raw material monomers of the styrene resin.

The softening point of the crystalline polyester resin is preferably 50°C or higher, more preferably 60°C or higher, from the viewpoint of storage stability, and preferably 130°C or lower, more preferably 120°C, from the viewpoint of low-temperature fixability. ℃ or less.

The melting point of the crystalline polyester resin is preferably 50°C or higher, more preferably 60°C or higher, from the viewpoint of storage stability, and preferably 130°C or lower, more preferably 120°C, from the viewpoint of low-temperature fixability. It is below.

The mass ratio of the amorphous polyester resin to the crystalline polyester resin (amorphous polyester resin/crystalline polyester resin) is preferably 70/30 or more, more preferably 75/25 or more, from the viewpoint of durability. It is more preferably 80/20 or more, and from the viewpoint of low-temperature fixability, preferably 97/3 or less, more preferably 95/5 or less.

The total content of the polyester resin in the binder resin 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.

The content of the binder resin in the toner base particles is preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, and still more preferably 75% by mass or more. It is less than 100% by mass, more preferably 98% by mass or less, and even more preferably 95% by mass or less.

As the coloring agent, dyes, pigments, magnetic substances, etc., which are used as coloring agents for toners, can be used. In the present invention, the toner may be black toner or color toner.

As the coloring agent, dyes, pigments, magnetic substances, etc., which are used as coloring agents for toners, can be used. For example, Carbon Black, Phthalocyanine Blue, Permanent Brown FG, Brilliant First Scarlet, Pigment Red 122, Pigment Green B, Rhodamine-B Base, Solvent Red 49, Solvent Red 146, Solvent Blue 35, Quinacridone, Carmine 6B, Isoindoline, Disazo Yellow. etc. In the present invention, the toner may be either black toner or color toner.

The content of the colorant is preferably 1 part by mass or more, more preferably 2 parts by mass or more with respect to 100 parts by mass of the binder resin, from the viewpoint of improving the image density and low-temperature fixability of the toner, and It is preferably 40 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less.

In addition to the binder resin and the colorant, the toner base particles contain release agents, charge control agents, magnetic powders, fluidity improvers, conductivity modifiers, reinforcing fillers such as fibrous substances, antioxidants, and cleaning agents. Additives such as a property improver may be contained, and it is preferable to contain a release agent and a charge control agent.

Release agents include hydrocarbon waxes such as polypropylene wax, polyethylene wax, polypropylene polyethylene copolymer wax, microcrystalline wax, paraffin wax, Fischer-Tropsch wax, oxides thereof; carnauba wax, montan wax and their Ester waxes such as deacidified waxes and fatty acid ester waxes; fatty acid amides, fatty acids, higher alcohols, fatty acid metal salts and the like; these may be used alone or in combination of two or more.

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

The content of the release agent is preferably 0.5 parts by mass or more, or more, with respect to 100 parts by mass of the binder resin, from the viewpoints of low-temperature fixability and anti-offset properties of the toner and dispersibility in the binder resin. It is preferably 1 part by mass or more, 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, and even more preferably 7 parts by mass or less.

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

Examples of positive charge control agents include nigrosine dyes such as "Nigrosine Base EX", "Oil Black BS", "Oil Black SO", "Bontron N-01", "Bontron N-04", and "Bontron N-07". , "Bontron N-09", "Bontron N-11" (manufactured by Orient Chemical Industry Co., Ltd.), etc.; triphenylmethane dyes containing tertiary amines as side chains; quaternary ammonium salt compounds, such as "Bontron P-51" (manufactured by Orient Chemical Industry Co., Ltd.), cetyltrimethylammonium bromide, "COPY CHARGE PX VP435" (manufactured by Clariant Co., Ltd.), etc.; ), etc.; imidazole derivatives, such as “PLZ-2001” and “PLZ-8001” (manufactured by Shikoku Kasei Co., Ltd.), etc.; styrene-acrylic resins, such as “FCA-701PT” and “FCA-201- PS" (manufactured by Fujikura Kasei Co., Ltd.) and the like.

In addition, as a negative charge control agent, a metal-containing azo dye such as "Barifast Black 3804", "Bontron S-31", "Bontron S-32", "Bontron S-34", "Bontron S-36" ” (manufactured by Orient Chemical Industry Co., Ltd.), “Aizenspiron Black TRH”, “T-77” (manufactured by Hodogaya Chemical Industry Co., Ltd.), etc.; metal compounds of benzilic 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 Industry Co., Ltd.), "TN-105" (manufactured by Hodogaya Chemical Industry Co., Ltd.), etc.; copper phthalocyanine dye; quaternary ammonium salt, such as "COPY CHARGE NX VP434" (manufactured by Clariant), nitroimidazole derivatives and the like; organometallic compounds and the like.

From the viewpoint of charging stability of the toner, the content of the charge control agent is preferably 2 parts by mass or more, more preferably 5 parts by mass or more, and still more preferably 10 parts by mass or more with respect to 100 parts by mass of the binder resin. Yes, and preferably 20 parts by mass or less, more preferably 18 parts by mass or less.

The toner base particles may be produced by any conventionally known method such as a melt-kneading method, an emulsification phase inversion method, and a polymerization method. A ground toner according to the method is preferred. Therefore, the toner base particles in the present invention are prepared by a kneading step of melting and kneading raw materials containing a binder resin, a colorant, and optionally a release agent, a charge control agent, etc., and a pulverizing step of pulverizing the resulting kneaded product. It is preferable to manufacture by a method comprising

The kneading step is a step of melt-kneading at least the binder resin and the colorant. The raw material to be melt-kneaded, including the binder resin and the colorant, may be kneaded all at once or divided and kneaded. preferably supplied to When the binder resin is composed of a plurality of resins, the plurality of resins may be mixed in advance, or each resin may be directly melt-kneaded when the toner is produced.

Melt-kneading can be performed using a known kneader such as a closed kneader, a single-screw or twin-screw extruder, and an open-roll kneader.

After melt-kneading, the kneaded product is preferably cooled until it reaches a pulverizable hardness, and then subjected to a pulverization step and, if necessary, a classification step to obtain toner base particles. Here, cooling means cooling the kneaded material to 0° C. or more and 50° C. or less, or cooling it to the glass transition temperature or less of the binder resin in the kneaded material.

The pulverization step is a step of pulverizing the obtained kneaded material to obtain toner base particles. The kneaded material may be pulverized to a desired particle size at once or in stages, but from the viewpoint of efficient and uniform pulverization, it is preferable to perform coarse pulverization and fine pulverization in two stages. preferable.

Examples of pulverizers used for coarse pulverization include hammer mills, atomizers, and rotoplexes.

In coarse pulverization, it is preferable to pulverize until the maximum diameter becomes 3 mm or less. The pulverized material with a maximum diameter of 3 mm or less is obtained by coarsely pulverizing the kneaded material to a particle size of 0.05 mm or more and 3 mm or less, passing it through a sieve with an opening of 3 mm, and obtaining a pulverized material that has passed through the sieve. can be done.

Pulverizers used for fine pulverization include jet mills such as fluidized bed jet mills and impingement plate jet mills, rotary mechanical mills, and the like. Among these, the fluidized bed jet mill and the impingement plate jet mill are preferred, and the impingement plate jet mill is more preferred, from the viewpoint of pulverization efficiency.

The degree of fine pulverization is preferably adjusted appropriately according to the desired particle size of the toner.

Classifiers used in the classification process include air classifiers, inertial classifiers, sieve classifiers, and the like.

After classification, spheronization may be performed by mechanical spheronization using a turbo mill, kryptron, faculty, or the like, or hot air spheronization using a Meteor Rainbow or the like.

The volume median particle diameter ( _D50 ) of the toner base 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 the present specification, the volume-median particle size (D ₅₀ ) means a particle size at which the cumulative volume frequency calculated as a volume fraction is 50% from the smaller particle size.

As the external additive, inorganic particles A having the opposite charging polarity and inorganic particles B having the same charging polarity as the toner base particles are used. Therefore, when the toner base particles are positively charged, the inorganic particles A are negatively charged and the inorganic particles B are positively charged. B is negatively charged. The chargeability of the toner base particles and the external additive can be confirmed by the sign of the charge amount measured by triboelectrification with iron powder. In the case of an external additive, it can also be determined by the surface treatment agent, functional groups, and the like. In the present invention, the charge polarity of the toner base particles may be selected according to the characteristics of the printer to be used.

The inorganic particles A have a number average particle diameter of 60 nm or more, preferably 70 nm or more, and more preferably 75 nm or more, because they are less likely to aggregate and have a greater fluidity-imparting effect. from the viewpoint of , it is 100 nm or less, preferably 98 nm or less, more preferably 95 nm or less.

The number average particle diameter of the inorganic particles B is 30 nm or more, preferably 40 nm or more, more preferably 45 nm or more, because of less aggregation, and is 60 nm or less, preferably 60 nm or less, from the viewpoint of charging stability. 55 nm or less, more preferably 50 nm or less.

Examples of inorganic particles used as an external additive include inorganic fine particles such as silica, alumina, titanium oxide, zirconia, strontium titanate, tin oxide, and zinc oxide. and inorganic particles B are preferably silica particles from the viewpoint of charging stability and fluidity.

From the viewpoint of charge polarity control, the inorganic particles are preferably treated with a surface treatment agent, and the charge polarity of the inorganic particles is imparted by the surface treatment agent with a charge polarity opposite to the charge polarity of the particles themselves. can be done. For example, although silica particles are negatively charged, they can be used as positively charged inorganic particles by introducing a positively chargeable group into the surface treatment agent.

General-purpose surface treatment agents include hydrophobizing agents such as hexamethyldisilazane (HMDS), polydimethylsiloxane (PDMS), and silicone oil.

Hydrophobizing agents such as hexamethyldisilazane (HMDS) and polydimethylsiloxane (PDMS) do not themselves affect the chargeability of inorganic particles, but the hydrophobizing agent has a group that imparts positive charging ability. By introducing the negative chargeability-imparting group, positive chargeability can be imparted to the negatively chargeable inorganic particles, and by introducing the negative chargeability imparting group, negative chargeability can be imparted to the positively chargeable inorganic particles.

Examples of the positively chargeable group include an amino group and the like.

Commercial products of positively charged silica include "RA 50 H", "NA 50 Y", "NA 50 H", "REA 90", "RA 200H", "RA 200 HS", "REA 200", " NA 300 H", (Nippon Aerosil Co., Ltd.), "TG-828F", "TG-820F", "TG-7120", "TG-6120F" (Cabot Specialty Chemicals, Inc.), etc. is mentioned.

Commercially available products of negatively charged silica include "RY 50", "RY 50 L", "RX 50", "NY 50", "NY 50 L", "R 972", "RY 200 S", "NX 130", "R974", "RY 200 L", "RX 200", "R 805", "NK 200", "R 976", "R 976 S", "RY 300", "RX 300" (and more , Nippon Aerosil Co., Ltd.), "TG-811F", "TG-810G", "TG-815F", "TG-3110", "TG-3155F", "TG-308F", "TG-3130", "TG-7180", "TG-7110", "TG-6110G", "TG-709G", "TG-5110", "TG-5150", "TG-5180", "TG-C413", "TG -C390", "TG-C243", "TG-C110", "TG-C191", "TG-C6020" (Cabot Specialty Chemicals, Inc.).

The inorganic particles A and the inorganic particles B are produced by mixing the inorganic particles A with the toner base particles and externally adding the inorganic particles A to the toner base particles, and mixing the inorganic particles B with the toner base particles and adding the inorganic particles B to the toner base particles. In the step B of externally adding the inorganic particles B, they are separately externally added to the toner base particles.

The amount of the inorganic particles A used in step A is 3.2 parts by mass or more, preferably 3.5 parts by mass or more, and more preferably 3.8 parts by mass or more from the viewpoint of coverage with respect to 100 parts by mass of the toner base particles. , and from the viewpoint of the liberated amount, it is 4.8 parts by mass or less, preferably 4.5 parts by mass or less, more preferably 4.3 parts by mass or less.

The amount of the inorganic particles B used in step B is 0.2 parts by mass or more, preferably 0.5 parts by mass or more, and more preferably 0.8 parts by mass or more from the viewpoint of coverage with respect to 100 parts by mass of the toner base particles. , and from the viewpoint of the liberated amount, it is 1.7 parts by mass or less, preferably 1.5 parts by mass or less, and more preferably 1.3 parts by mass or less.

The order of the steps A and B is not limited, and the step B may be performed after the step A or the step A may be performed after the step B. It is preferable to perform the step B after the step A from the viewpoint of preferentially attaching the large-diameter inorganic particles A, which are difficult to adhere to the toner base particles.

The external addition treatment by mixing the toner base 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.

In the present invention, after steps A and B, further
To the toner base particles externally added with inorganic particles A and inorganic particles B, polymer beads C having a particle size larger than that of the inorganic particles A and oppositely charged to the toner base particles are mixed, and the polymer beads are mixed with the toner base particles. Step C of externally adding C
It is preferable to The polymer beads C having a large particle size are easily removed from the surface of the toner base particles, and the liberated polymer beads C act as microcarriers. is further improved.

The number average particle size of the polymer beads C is preferably 200 nm or more, preferably 1000 nm or less, more preferably 500 nm or less.

Positively charged polymer beads C include melamine-formaldehyde resin, styrene (St)/methyl methacrylate (MMA) copolymer, St/butyl acrylate (BA) copolymer, MMA/BA copolymer, and the like. . Specifically, "Eposter S", "Eposter SS", "Eposter S6", "Eposter S12", "Eposter MS", "Eposter M05", "Eposter L15", "Eposter M30" Nippon Shokubai), "FFP-8202", "FFP-8203", and "FFP-8252" (all of which are Fujikura Kasei Co., Ltd.).

Examples of the negatively charged polymer beads C include fluorine-based resins such as polytetrafluoroethylene, trifluoroethylene, vinylidene fluoride, and fluoroethylene. Specifically, "L-5F" (above, Daikin Industries, Ltd.), "KTL-500F" (above, Kitamura Co., Ltd.) and the like can be mentioned.

The amount of polymer beads C used in step C is preferably 0.1 parts by mass or more, more preferably 0.15 parts by mass or more, and still more preferably 0.18 parts by mass or more from the viewpoint of charging stability with respect to 100 parts by mass of the toner base particles. And, from the viewpoint of durability, it is preferably 1 part by mass or less, more preferably 0.5 parts by mass or less, and still more preferably 0.3 parts by mass or less.

The toner obtained by the method of the present invention may contain external additives other than inorganic particles A and B and polymer beads C, but the total content of inorganic particles A and inorganic particles B is , preferably 80% by mass or more, more preferably 90% by mass or more, and 100% by mass or less, preferably 99% by mass or less.

The total content of inorganic particles A, inorganic particles B and polymer beads C in the external additive 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 98% by mass or more, more preferably 100% by mass.

According to the method of the present invention, the external additive can be efficiently externally added to the toner base particles.
In the toner of the present invention, formula (1):

is preferably 40% or higher, more preferably 50% or higher, even more preferably 60% or higher, and still more preferably 70% or higher.

Here, the actual coverage rate was calculated as the rate on the toner surface by digitizing the convex portions on the toner surface using image analysis software. Specifically, scanning electron microscope (SEM) photographs of the surface of the toner subjected to the external additive treatment were analyzed using image analysis software (public domain software ImageJ). Measure the projected area of the external additive on the surface and use the formula (2):

Then, the average value of 10 toner particles is calculated. Furthermore, a correction coefficient (42) is added because the contrast difference between the toner and the external additive is reduced.

On the other hand, the calculated coverage is calculated according to the method described in Ricoh technical report (2000), assuming that the toner base particles and the external additive are spherical, using formula (3):

(where _Dt is the volume median particle size of the toner base particles, _ρt is the true specific gravity of the toner base particles, _Da is the number average particle size of the external additive, _ρa is the true specific gravity of the external additive, W _a indicates the ratio of the amount of the external additive added to the weight of the toner base particles)
Calculate from
In the present invention, since two or more types of external additives are used, the calculated coverage for each external additive is calculated, and the sum of these is taken as the calculated coverage of the external additive.

The toner obtained by the method of the present invention can be used as a toner for one-component development or as a two-component developer by mixing with a carrier in an image forming apparatus of a one-component development system or a two-component development system, respectively.

EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these Examples. Physical properties of resins and the like can be measured by the following methods.

[Resin softening point]
Using a flow tester "CFT-500D" (manufactured by Shimadzu Corporation), while heating a 1 g sample at a temperature increase rate of 6 ° C / min, a load of 1.96 MPa was applied with a plunger, and the diameter was 1 mm and the length was 1 mm. extruded from the nozzle of Plot the amount of plunger descent of the flow tester against the temperature, and let the softening point be the temperature at which half of the sample flows out.

[Maximum peak temperature of resin absorption]
Using a differential scanning calorimeter "Q-100" (manufactured by TA Instruments Japan Co., Ltd.), weigh 0.01 to 0.02 g of the sample in an aluminum pan and cool it from room temperature (25 ° C) to a cooling rate of 10 ° C. /min to 0°C and hold at 0°C for 1 minute. After that, measure at a heating rate of 10°C/min. Among the observed endothermic peaks, the temperature of the peak having the maximum peak area is defined as the maximum endothermic peak temperature.

[Glass transition temperature of amorphous resin]
Using a differential scanning calorimeter "Q-100" (manufactured by TA Instruments Japan), weigh 0.01 to 0.02 g of the sample in an aluminum pan, raise the temperature to 200 ° C, and then decrease the cooling rate from that temperature. Cool to 0°C at 10°C/min. Next, the sample is heated at a heating rate of 10°C/min, and the endothermic peak is measured. The glass transition temperature is defined as the temperature at the intersection of the extended line of the baseline below the maximum endothermic peak temperature and the tangent line showing the maximum slope from the rising portion of the peak to the apex of the peak.

[Acid value of amorphous resin]
Measured based on the method of JIS K 0070:1992. However, only the measurement solvent is changed 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)).

[Melting point of release agent]
Using a differential scanning calorimeter "Q100" (manufactured by TA Instruments Japan Co., Ltd.), 0.02 g of the sample was weighed into an aluminum pan, heated to 200 ° C, and then cooled from 200 ° C at a cooling rate of 10 ° C/min. Cool to 0°C. Next, the temperature of the sample is increased at a temperature increase rate of 10°C/min, the calorie is measured, and the maximum endothermic peak temperature is defined as the melting point.

[Volume Median Particle Diameter ( _D50 ) of Toner Base Particles]
・Measuring machine: Coulter Multisizer II (manufactured by Beckman Coulter, Inc.)
・Aperture diameter: 100 μm
・Analysis software: Coulter Multisizer AccuComp version 1.19 (manufactured by Beckman Coulter, Inc.)
・Electrolyte: Isoton II (manufactured by Beckman Coulter, Inc.)
・Dispersion: Emulgen 109P (manufactured by Kao Corporation, polyoxyethylene lauryl ether, HLB (griffin): 13.6) was dissolved in the electrolytic solution and adjusted to 5% by mass ・Dispersion conditions: Measured on 5 mL of the dispersion Add 10 mg of sample and disperse for 1 minute with an ultrasonic disperser (machine name: US-1 manufactured by SND Co., Ltd., output: 80 W). (Machine name: US-1 manufactured by SND Co., Ltd., output: 80 W) for 1 minute to prepare a sample dispersion.
・Measurement conditions: By adding the sample dispersion to 100 mL of the electrolytic solution, the particle size of 30,000 particles is adjusted to a concentration that can be measured in 20 seconds, and then 30,000 particles are measured. The volume median particle size ( _D50 ) is determined from the distribution.

[Number average particle size of external additive]
The particle size (average value of the major axis and minor axis) of 500 particles is measured from a scanning electron microscope (SEM) photograph, and the average value is defined as the number average particle size.

Resin production example 1
An alcohol component, a carboxylic acid component other than trimellitic anhydride, and an esterification catalyst shown in Table 1 were placed in a 10 L four-necked flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer and a thermocouple, and placed under a nitrogen atmosphere. , the temperature was raised to 200° C. and the reaction was allowed to proceed for 6 hours. Furthermore, after the temperature was raised to 210° C., trimellitic anhydride was added and reacted for 1 hour at normal pressure (101.3 kPa). After that, the mixture was reacted at 40 kPa until it reached the desired softening point to obtain an amorphous polyester resin (resin A1). Table 1 shows the physical properties of the obtained resin.

Resin production example 2
The raw material monomers for the crystalline polyester resin and the esterification catalyst shown in Table 2 were placed in a 10 L four-necked flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer and a thermocouple, heated to 160°C, and reacted for 6 hours. let me After that, the raw material monomer for the styrenic resin shown in Table 2, the bi-reactive monomer, and the polymerization initiator were added dropwise with a dropping funnel over 1 hour. After aging the addition polymerization reaction for 1 hour while maintaining the temperature at 160° C., the raw material monomer of the styrene resin was removed for 1 hour at 8.3 kPa. Further, the temperature was raised to 200° C. over 8 hours, and the mixture was reacted at 8.3 kPa for 2 hours to obtain a crystalline composite resin (resin C1). Table 2 shows the physical properties of the obtained resin.

Examples 1-6 and Comparative Examples 1-8
90 parts by mass of resin A1, 10 parts by mass of resin C1, 6 parts by mass of carbon black (REGAL 330R, manufactured by Cabot Specialty Chemicals, Inc.), ester wax (WE-14, manufactured by NOF Corporation, melting point: 78 ℃) and 15 parts by mass of a positive charge control agent (Bontron P-51, manufactured by Orient Chemical Industry Co., Ltd.) are premixed and kneaded in an open-roll type twin-screw kneader (front roll temperature: 160°C, back roll temperature: 35°C, mixture feed rate: 10 kg/h). After cooling, it is coarsely pulverized with a mechanical pulverizer "Roadplex" (manufactured by Hosokawa Micron Co., Ltd.) to the extent that it can pass through a mesh with an opening of 2 mm. (manufactured by Hosokawa Micron Co., Ltd.) was used to finely pulverize the toner by adjusting the pulverization pressure so that the volume median particle diameter (D ₅₀ ) was 7.5 μm. The particles were conditioned and spheroidized to obtain positively chargeable toner base particles.

External additives for the first to third stages shown in Tables 4 and 5 (only the first and second stages in Comparative Example 8) were sequentially mixed and externally added to the obtained toner base particles. got Mixing of the external additives in the first to third stages was performed for 5 minutes using a Henschel mixer (manufactured by Nippon Coke Kogyo Co., Ltd.) at 2100 r/min (peripheral speed of 29 m/sec).

The details of the external additives used in Examples and Comparative Examples are as follows.

Test example A laser printer "HL-2040" manufactured by Brother Industries, Ltd. was filled with 30 g of toner, and a line image of 1 dot, 3 spaces was printed under conditions of a temperature of 25°C and a humidity of 50%. Using a handy type image quality analyzer "PIAS-II" manufactured by Fujikura Co., Ltd., the raggedness of the upper and lower ends of each line was measured for 10 lines, and the average value was used as an index of fine line reproducibility. Note that raditness is a value defined by ISO13660, and represents how wavy the ideal line edge should be, which should be smooth and straight. The smaller the value, the better the reproducibility of fine lines. ing. Tables 4 and 5 show the results.

From the above results, it can be seen that the toners obtained in Examples 1-6 exhibit good fine line reproducibility as compared with Comparative Examples 1-8.

The electrostatic charge image developing toner obtained by the method of the present invention is suitably used for developing latent images formed by electrophotography, electrostatic recording, electrostatic printing and the like.

Claims (7)

Toner base particles containing a binder resin and a colorant, inorganic particles A having a number average particle diameter of 60 nm or more and 100 nm or less and oppositely charged to the toner base particles, and a number average particle diameter of 30 nm or more and 60 nm or less. and an external additive containing inorganic particles B having the same charging polarity as the toner base particles, and a method for producing a toner for electrostatic charge image development,
A step A of mixing the toner base particles and 3.2 parts by mass or more and 4.8 parts by weight or less of inorganic particles A with respect to 100 parts by weight of the toner base particles, and externally adding the inorganic particles A to the toner base particles; Step B of mixing the mother particles and 0.2 parts by mass or more and 1.7 parts by mass or less of the inorganic particles B with respect to 100 parts by mass of the toner mother particles, and externally adding the inorganic particles B to the toner mother particles.
A method for producing a toner for developing an electrostatic charge image, comprising: 2. The production method according to claim 1, wherein the inorganic particles A and the inorganic particles B are silica particles. After steps A and B, further
To toner base particles externally added with inorganic particles A and inorganic particles B, polymer beads C having a number average particle diameter of 200 nm or more and 1000 nm or less and oppositely charged to the toner base particles are mixed, and inorganic particles are added to the toner base particles. Step C of externally adding particles B
The manufacturing method according to claim 1 or 2, comprising: The production method according to any one of claims 1 to 3, wherein step B is performed after step A. 5. The production method according to any one of claims 1 to 4, wherein the binder resin contains 80% by mass or more of the polyester resin. In toner, formula (1):

6. The manufacturing method according to any one of claims 1 to 5, wherein the coating efficiency P of the external additive calculated from is 50% or more. 7. The production method according to claim 1, wherein the toner base particles are positively chargeable, the inorganic particles A are negatively chargeable, and the inorganic particles B are positively chargeable.