JP6699337B2 - Toner for electrostatic latent image development - Google Patents

Description

  The present invention relates to a toner for developing an electrostatic latent image.

  In recent years, in an electrophotographic image forming apparatus, an electrostatic latent image developing toner (hereinafter also simply referred to as “toner”) that is heat-fixed at a lower temperature is required in order to further save energy. ing. Such toners are required to be able to form images having excellent low-temperature fixability and few defects.

  As a technique for solving such a problem, for example, in Patent Document 1, a crystalline polyester resin having an unsaturated double bond, a thiol compound containing a bifunctional or higher thiol group, and a photopolymerization initiator A toner is disclosed which is characterized by containing. With such a structure, it is said that a toner excellent in low-temperature fixability can be obtained and an image excellent in scratch resistance can be obtained.

JP, 2014-178592, A

  However, the technique described in Patent Document 1 has a problem that when the formed image is folded, image peeling occurs at the folded portion.

  Therefore, an object of the present invention is to provide a toner for developing an electrostatic latent image, which has improved low-temperature fixability and suppressed image peeling at a folded portion.

The present inventors have conducted earnest research to solve the above problems. As a result, an electrostatic latent image developing toner containing toner particles containing a binder resin, wherein the softening point of the toner is 115° C. or lower and a sapphire needle having a tip diameter of 50 μm is used. For developing an electrostatic latent image, a critical load of which is 30 gf or more when a scratch test of the surface of an image formed by the toner formed on a glass substrate with an adhesion amount of 16 g/m ² is performed by a friction and abrasion tester. The present inventors have found that the above problems can be solved by toner, and have completed the present invention.

  According to the present invention, there is provided an electrostatic latent image developing toner having improved low-temperature fixability and suppressed image peeling at a folded portion.

The present invention relates to an electrostatic latent image developing toner containing toner particles containing a binder resin, wherein the toner has a softening point of 115° C. or lower and a sapphire needle having a tip diameter of 50 μm, and load fluctuations. Electrostatic latent image development, the critical load of which is 30 gf or more when a scratch test of the surface of the image formed by the toner formed on the glass substrate with an adhesion amount of 16 g/m ² is performed by a friction abrasion tester. For toner. The electrostatic latent image developing toner of the present invention having such a structure has improved low-temperature fixability, and image peeling at the folded portion is suppressed.

  In the technique described in Patent Document 1, the image formed by the toner is irradiated with light to cure the image. Although the strength of the image is increased by photo-curing and the scratch resistance is improved, the image is too hard, is not flexible and is fragile, and thus there is a problem that when the image is folded, the image peels off at the folded portion.

On the other hand, the toner of the present invention is subjected to a scratch test of the surface of the image formed by the toner formed on the glass substrate at an adhesion amount of 16 g/m ² by a load variation type friction and abrasion tester (hereinafter, also simply referred to as “scratch test”). ), the critical load is 30 gf or more. In this scratch test, it can be said that the adhesion between the toners is evaluated, so to speak, the toner having a critical load as described above has a strong adhesion between the toners, and image peeling at the folded portion when the image is folded It is suppressed and image defects are reduced.

  Further, the toner of the present invention has a softening point of 115° C. or lower, which improves low-temperature fixability. Generally, an image formed with a toner having a low softening point tends to be brittle at room temperature. Therefore, the adhesiveness tends to be low, and the folding strength and the like tend to be low (image peeling at the folding portion is likely to occur). However, although the toner of the present invention has a low softening point, the image formed from the toner has a high critical load in the scratch test. This means that the toner of the present invention and the formed image have high viscosity. That is, the toner of the present invention is not only soft but also has a high viscosity, so that the adhesiveness between the formed images is improved. As a result, the toner of the present invention can form an image in which the peeling of the image at the folded portion is suppressed while the low-temperature fixability is improved, and it is possible to obtain an effect that cannot be obtained by the conventional toner.

  The above mechanism is based on speculation, and its correctness does not affect the technical scope of the present invention.

  Embodiments of the present invention will be described below. The present invention is not limited to the following embodiments. Unless otherwise specified, operations and measurements of physical properties are carried out under the conditions of room temperature (20 to 25° C.)/relative humidity 40 to 50% RH.

[toner]
The toner of the present invention contains toner particles containing a binder resin, and the toner particles contain other toner constituent components such as a colorant, a magnetic powder, a release agent and a charge control agent, if desired. Can be something. Further, an external additive such as a fluidizing agent or a cleaning aid may be added to the toner particles.

  Further, the toner of the present invention is obtained by a wet production method, such as an emulsion aggregation method, which is produced in an aqueous medium.

[Binder resin]
The resin contained in the binder resin according to the present invention is not particularly limited, and examples thereof include an amorphous resin and a crystalline resin.

(Amorphous resin)
Specific examples of the amorphous resin include resins obtained by polymerizing vinyl monomers such as acrylic resins and styrene-acrylic copolymer resins.

The following can be used as the vinyl monomer. The vinyl monomer may be used alone or in combination of two or more.
(1) Styrene monomer Styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert- Butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene and derivatives thereof.
(2) (meth)acrylic acid ester monomer Methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isopropyl (meth)acrylate, isobutyl (meth)acrylate, ( T-butyl (meth)acrylate, phenyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate and derivatives thereof.
(3) Vinyl esters Vinyl propionate, vinyl acetate, vinyl benzoate, etc.
(4) Vinyl ethers Vinyl methyl ether, vinyl ethyl ether and the like.
(5) Vinyl ketones Vinyl methyl ketone, vinyl ethyl ketone, vinyl hexyl ketone and the like.
(6) N-vinyl compounds N-vinylcarbazole, N-vinylindole, N-vinylpyrrolidone and the like.
(7) Others Vinyl compounds such as vinylnaphthalene and vinylpyridine, acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile and acrylamide.

  In addition, as the vinyl monomer, it is preferable to use a monomer having an ionic dissociative group such as a carboxy group, a sulfonic acid group, or a phosphoric acid group. Specifically, there are the following.

  Examples of the monomer having a carboxy group include acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumaric acid, maleic acid monoalkyl ester and itaconic acid monoalkyl ester. Examples of the monomer having a sulfonic acid group include styrenesulfonic acid, allylsulfosuccinic acid, 2-acrylamido-2-methylpropanesulfonic acid and the like. Furthermore, acid phosphooxyethyl methacrylate etc. are mentioned as a monomer which has a phosphoric acid group.

  Furthermore, it is preferable to use a (meth)acrylic acid ester monomer having a long-chain alkyl group represented by the following formula (1) as the vinyl monomer. By using such a monomer, the elasticity of the obtained resin is improved, and the toner containing such a resin has a higher critical load measured by a scratch test. Therefore, when the resin containing the constitutional unit derived from the monomer represented by the following chemical formula (1) is contained in the binder resin constituting the toner particles, the adhesiveness between the toner particles is further enhanced, and the toner particles at the folded portion are Image peeling is further suppressed. That is, according to a preferred embodiment of the present invention, the binder resin includes a resin having a structural unit derived from a (meth)acrylic acid ester monomer represented by the following chemical formula (1).

In the above chemical formula (1), R ₁ is a hydrogen atom or a methyl group, R ₂ is an alkyl group having a main chain of 5 or more carbon atoms, and in this case, R ₂ is an alkyl group bonded to the main chain. It may be a branched alkyl group.

Examples of the alkyl group used for R ₂ include n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-decyl group, n-dodecyl group, n-lauryl group, n-tetradecyl group. Group, n-hexadecyl group, n-octadecyl group, isopentyl group, amyl group, neopentyl group, isohexyl group, isoheptyl group, isooctyl group, 2-ethylhexyl group, 1-methylheptyl group, 2-propylhexyl group, 2-propyl Examples thereof include a heptyl group, a 6-methylheptyl group, an isononyl group, an isodecyl group, a tridecyl group and an isostearyl group.

  Examples of the (meth)acrylic acid ester monomer represented by the above chemical formula (1) include, for example, n-pentyl(meth)acrylate, n-hexyl(meth)acrylate, n-heptyl(meth)acrylate, n. -Octyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, n-lauryl (meth)acrylate, n-tetradecyl (meth)acrylate, n-hexadecyl (meth)acrylate, n-octadecyl (Meth)acrylate, isopentyl(meth)acrylate, amyl(meth)acrylate, neopentyl(meth)acrylate, isohexyl(meth)acrylate, isoheptyl(meth)acrylate, isooctyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, 2 -Propylhexyl (meth)acrylate, 1-methylheptyl (meth)acrylate, 2-propylheptyl (meth)acrylate, 6-methylheptyl (meth)acrylate, isononyl (meth)acrylate, isodecyl (meth)acrylate, tridecyl (meth) ) Acrylics, (meth)acrylic acid alkyl esters such as isostearyl (meth)acrylate, and the like. These monomers can be used alone or in combination of two or more. Among these, 2-ethylhexyl (meth)acrylate and 2-propylhexyl (meth)acrylate are more preferable.

The upper limit of the number of carbon atoms (total of main chain and side chain) of the alkyl group used for R ₂ in the above chemical formula (1) is not particularly limited, but is preferably 22 or less.

  In the present specification, “(meth)acrylic acid ester monomer” is a generic term for “acrylic acid ester monomer” and “methacrylic acid ester monomer”. ) "Methyl acrylate" is a generic term for "methyl acrylate" and "methyl methacrylate".

  In addition, it is preferable to use a bifunctional (meth)acrylic acid ester monomer as the vinyl monomer. By using such a monomer, the resulting resin has a crosslinked structure, the elasticity of the resin is further improved, and a toner containing such a resin has a further critical load measured by a scratch test. It will be expensive. Therefore, when the resin containing the constitutional unit derived from the bifunctional (meth)acrylic acid ester monomer is contained in the binder resin that constitutes the toner particles, the binder resin becomes tough and image peeling at the folded portion occurs. Further suppressed. That is, according to a preferred embodiment of the present invention, the binder resin contains a resin having a structural unit derived from a bifunctional (meth)acrylic acid ester monomer.

  Examples of the bifunctional (meth)acrylic acid ester monomer include methylene glycol di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, propylene glycol. Di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decane Examples thereof include diol di(meth)acrylate. These can be used alone or in combination of two or more. Among these, polyethylene glycol di(meth)acrylate is preferable, polyethylene glycol diacrylate (see the following chemical formula) is more preferable, and polyethylene glycol diacrylate in which n in the following chemical formula is 4 to 13 is further preferable.

  The structural unit derived from the (meth)acrylic acid ester monomer having a long-chain alkyl group represented by the chemical formula (1) and the structural unit derived from the bifunctional (meth)acrylic acid ester monomer will be described later. It may be contained in the amorphous polymerized segment of the hybrid crystalline polyester resin of, or may be contained in the amorphous resin constituting the surface layer of the composite particles described later, and is not particularly limited.

  The content of the constituent unit derived from the (meth)acrylic acid ester monomer having a long-chain alkyl group represented by the above chemical formula (1) in the amorphous resin or the amorphous polymerized segment is not particularly limited, It is preferably 2.0 to 13.5% by mass, and more preferably 2.5 to 13.5% by mass, based on the total mass of the binder resin. Further, the content of the constituent unit derived from the bifunctional (meth)acrylic acid ester monomer in the amorphous resin or the amorphous polymerized segment is not particularly limited, but is 0 relative to the total mass of the binder resin. It is preferably 0.3 to 6.0% by mass, more preferably 0.5 to 5.0% by mass.

(Crystalline polyester resin)
The binder resin according to the present invention preferably contains a crystalline resin, and the crystalline resin is preferably a crystalline polyester resin. Since the crystalline polyester resin has a relatively high compatibility with the amorphous resin, the binding property of the binder resin is improved, the stress is easily relieved when the image is folded, and the image peeling at the folded portion does not occur. More suppressed.

  The crystalline polyester resin that can be contained in the binder resin is a known polyester resin obtained by a polycondensation reaction of a divalent or higher carboxylic acid (polyvalent carboxylic acid) and a divalent or higher alcohol (polyhydric alcohol). Among them, in differential scanning calorimetry (DSC), it means a resin having a clear endothermic peak instead of a stepwise endothermic change. The clear endothermic peak specifically means a peak in which the half width of the endothermic peak is within 15° C. when measured at a temperature rising rate of 10° C./min in differential scanning calorimetry (DSC). To do.

  The polycarboxylic acid is a compound containing two or more carboxy groups in one molecule. Specifically, for example, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid ( Dodecanedioic acid), 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,13-tridecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,16-hexadecanedicarboxylic acid, 1,18- Saturated aliphatic dicarboxylic acids such as octadecane dicarboxylic acid; Alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid; Aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid; Trivalent or trivalent acids such as trimellitic acid and pyromellitic acid Examples thereof include polyvalent carboxylic acids; and anhydrides of these carboxylic acid compounds, and alkyl esters having 1 to 3 carbon atoms. These may be used alone or in combination of two or more.

  Polyhydric alcohol is a compound containing two or more hydroxyl groups in one molecule. Specifically, for example, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptane Diol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecane Aliphatic diols such as diols, 1,16-hexadecanediol, 1,18-octadecanediol, 1,20-eicosanediol, neopentyl glycol, 1,4-butenediol; glycerin, pentaerythritol, trimethylolpropane, sorbitol. And polyhydric alcohols with 3 or more valences. These may be used alone or in combination of two or more.

  The melting point (Tm) of the crystalline polyester resin is preferably 40 to 95°C, more preferably 50 to 85°C. When the melting point of the crystalline polyester resin is within the above range, sufficient low temperature fixability and excellent hot offset resistance can be obtained.

  The melting point of the crystalline polyester resin can be controlled by the resin composition.

  In the present invention, the melting point of the crystalline polyester resin is a value measured as follows.

  Specifically, using a differential scanning calorimeter “Diamond DSC” (manufactured by Perkin Elmer Co., Ltd.), a first temperature raising process of raising the temperature from 0° C. to 200° C. at a lifting speed of 10° C./min, a cooling rate of 10° C./min. Measured under the measurement conditions (heating/cooling conditions) that undergo the cooling process of cooling from 200° C. to 0° C. at 2° C. and the second heating process of heating from 0° C. to 200° C. at a lifting speed of 10° C./min in this order. Based on the DSC curve obtained by this measurement, the endothermic peak top temperature derived from the crystalline polyester resin in the first heating process is taken as the melting point. As a measurement procedure, 3.0 mg of a measurement sample (crystalline polyester resin) is enclosed in an aluminum pan and set in a diamond DSC sample holder. The reference uses an empty aluminum pan.

  The crystalline polyester resin preferably has a weight average molecular weight (Mw) of 5,000 to 50,000 and a number average molecular weight (Mn) of 1, as measured by gel permeation chromatography (GPC). It is preferably 500 to 25,000.

  The molecular weight of the crystalline polyester resin measured by gel permeation chromatography (GPC) is a value measured as follows.

  Specifically, using an apparatus “HLC-8120GPC” (manufactured by Tosoh Corporation) and a column “TSKguardcolumn+TSKgelSuperHZ-M3 series” (manufactured by Tosoh Corporation) while maintaining the column temperature at 40° C., tetrahydrofuran (THF) as a carrier solvent. ) Is flown at a flow rate of 0.2 ml/min, and the measurement sample is dissolved in tetrahydrofuran so as to have a concentration of 1 mg/ml under dissolution conditions in which treatment is performed for 5 minutes using an ultrasonic disperser. Then, a sample solution is obtained by treating with a membrane filter having a pore size of 0.2 μm, 10 μL of this sample solution is injected into the apparatus together with the above-mentioned carrier solvent, and detection is performed using a refractive index detector (RI detector) and measurement is performed. The molecular weight distribution of the sample is calculated using a calibration curve measured using monodisperse polystyrene standard particles. Ten points are used as polystyrene for measuring the calibration curve.

  The crystalline polyester resin preferably has an ester group concentration of 0.05 mmol/g or more and 15 mmol/g or less, and more preferably 0.1 mmol/g or more and 12 mmol/g or less. Within such a range, the compatibility between the crystalline polyester resin and the amorphous resin is further enhanced, and the binding property between the resins is enhanced, so that stress relaxation when the image is folded is more likely to occur, and The peeling of the image in the area is further suppressed.

  Here, the ester group concentration is the ratio of ester groups (ester bonds) in the crystalline polyester resin. In the present invention, the ester group concentration is a value calculated by the following mathematical formula (A).

Formula (A): Concentration of ester group=[average number of moles of a portion that can be an ester group contained in the polyvalent carboxylic acid and polyhydric alcohol forming the crystalline polyester resin/((of polyvalent carboxylic acid and polyhydric alcohol Total molecular weight)-(molecular weight of water separated by dehydration polycondensation x number of moles of ester group))] x 1000
The ester group concentration of this crystalline polyester resin can be controlled by the type of monomer used.

  An example of calculating the ester group concentration of the crystalline polyester resin is shown below.

The crystalline polyester resin obtained from the polyhydric carboxylic acid represented by the following formula (a) and the polyhydric alcohol represented by the following formula (b) is represented by the following formula (c).
Formula _{(a): HOOC-R 3} -COOH
Equation _{(b): HO-R 4} -OH
Formula _{(c): - (- OCO} -R 3 -COO-R 4 -) n -
"The average number of moles of the part that can be an ester group contained in the polyvalent carboxylic acid and polyhydric alcohol forming the crystalline polyester resin" is the number of moles of the carboxy group of the polyvalent carboxylic acid forming the crystalline polyester resin. And the average of the number of moles of the hydroxyl group of the polyhydric alcohol, and specifically, the number of moles of the carboxy group of the polyvalent carboxylic acid of formula (a) "2" and the hydroxyl number of the polyhydric alcohol of formula (b). It is an average of "2" with the number of moles of the group being "2".

  When the molecular weight of the polyhydric carboxylic acid of the formula (a) is m1, the molecular weight of the polyhydric alcohol of the formula (b) is m2, and the molecular weight of the crystalline polyester resin of the formula (c) is m3, “(polyvalent carboxylic acid "(Total molecular weight of acid and polyhydric alcohol)-(molecular weight of water separated by dehydration polycondensation x number of moles of ester group)" is (m1+m2)-(18 x average number of moles of ester group "2"). Therefore, the molecular weight of the crystalline polyester resin of the formula (c) is “m3”.

  From the above, the ester group concentration of the crystalline polyester resin represented by the formula (c) is “2/m3”.

  When two or more polyvalent carboxylic acids or two or more polyhydric alcohols are used in combination, the number of moles of carboxy groups of polyvalent carboxylic acid and the average molecular weight, and the number of moles of hydroxyl groups of polyvalent alcohols and It is calculated and calculated from the average of the molecular weights.

  In the present invention, in order to measure the ester group concentration and melting point of the crystalline polyester resin, and the carboxy group concentration of the amorphous resin described below, it is necessary to extract each resin contained in the toner particles. Specifically, the resin can be extracted from the toner particles as follows.

  First, the toner is dissolved in methyl ethyl ketone (MEK) at room temperature (20° C. or higher and 25° C. or lower). Here, the amorphous resin in the toner particles is dissolved in MEK at room temperature. Therefore, since the MEK soluble component contains the amorphous resin, the amorphous resin can be obtained from the supernatant liquid separated by centrifugation after the dissolution. On the other hand, the solid content after centrifugation is heated at 65° C. for 60 minutes to dissolve it in tetrahydrofuran (THF), and this is filtered with a glass filter at 60° C. to obtain a crystalline polyester resin from the filtrate. In addition, since crystalline polyester resin will precipitate if the temperature falls during filtration by the said operation, it operates in the state kept warm.

  The ester group concentration of the crystalline polyester resin is measured by P-GC/MS after hydrolyzing the crystalline polyester resin, and by specifying the monomer species of each of the polycarboxylic acid and the polyhydric alcohol. It can also be calculated.

  The method for producing the crystalline polyester resin is not particularly limited, and it can be produced by polycondensing (esterifying) the polyvalent carboxylic acid and the polyhydric alcohol using a known esterification catalyst.

As a catalyst that can be used in the production of the crystalline polyester resin, an alkali metal compound such as sodium and lithium; a compound containing a Group 2 element such as magnesium and calcium; aluminum, zinc, manganese, antimony, titanium, tin, Examples thereof include compounds of metals such as zirconium and germanium; phosphorous acid compounds; phosphoric acid compounds; and amine compounds. Specific examples of the tin compound include dibutyltin oxide (dibutyltin oxide), tin octylate, tin dioctylate, salts thereof, and the like. Examples of titanium compounds include titanium alkoxides such as tetranormal butyl titanate (Ti(O-n-Bu) ₄ ), tetraisopropyl titanate, tetramethyl titanate, and tetrastearyl titanate; titanium acylates such as polyhydroxytitanium stearate; titanium tetra Examples thereof include titanium chelates such as acetylacetonate, titanium lactate, and titanium triethanolaminate. Examples of the germanium compound include germanium dioxide. Further, examples of the aluminum compound include oxides such as polyaluminum hydroxide, aluminum alkoxide, and the like, and tributylaluminate and the like can be given. You may use these individually by 1 type or in combination of 2 or more type.

  The polymerization temperature is not particularly limited, can be appropriately adjusted to obtain the desired product, and is preferably 70 to 250°C. The polymerization time is not particularly limited, but it is preferably 0.5 to 10 hours. During the polymerization, the pressure inside the reaction system may be reduced if necessary.

  The mass ratio of the binder resin other than the crystalline polyester resin and the crystalline polyester resin (the binder resin other than the crystalline polyester resin/the crystalline polyester resin) is preferably 97/3 to 60/40, and It is preferably 95/5 to 70/30. Within this range, the low temperature fixability is good and the toner chargeability is also improved.

(Hybrid crystalline polyester resin)
In the present invention, it is preferable to use a hybrid crystalline polyester resin partially containing the structure of the amorphous resin in the toner particles. That is, according to the present invention, it is more preferable that the crystalline polyester resin is a hybrid crystalline polyester resin.

  In a preferred embodiment of the present invention, the hybrid crystalline polyester resin is a resin in which a crystalline polyester polymer segment and an amorphous polymer segment other than the polyester polymer segment are chemically bonded. Since the hybrid crystalline polyester resin can be the domain phase of the domain matrix structure, such a form improves the adhesion to the amorphous resin that can be the matrix phase in the toner particles, and when an image is folded, The stress relaxation is more likely to occur, and image peeling at the folded portion is further suppressed.

  The structure chemically bonded is not particularly limited, but the crystalline polyester polymerized segment is preferably grafted with the amorphous polymerized segment as the main chain. That is, the hybrid crystalline polyester resin is preferably a graft copolymer having the amorphous polymerized segment as the main chain and the crystalline polyester polymerized segment as the side chain.

  More specifically, the hybrid crystalline polyester resin is preferably a hybrid crystalline polyester resin in which a crystalline polyester polymerized segment which is a side chain is bonded to the main chain of a styrene acrylic polymerized segment which is an amorphous polymerized segment.

<Crystalline polyester polymerized segment>
The crystalline polyester polymerized segment refers to a portion derived from a crystalline polyester resin. That is, it refers to a molecular chain having the same chemical structure as that of the crystalline polyester resin.

  The crystalline polyester polymerized segment is the same as the crystalline polyester resin described above, and is a portion derived from a known polyester resin obtained by a polycondensation reaction of a polyvalent carboxylic acid and a polyhydric alcohol. The polyvalent carboxylic acid and the polyhydric alcohol that constitute the crystalline polyester polymerized segment are the same as those of the crystalline polyester resin described above, and thus the description thereof is omitted.

  The content of the crystalline polyester polymerized segment is preferably 80% by mass or more and 98% by mass or less and more preferably 90% by mass or more and 95% by mass or less with respect to the total amount of the hybrid crystalline polyester resin. With the above range, sufficient crystallinity can be imparted to the hybrid crystalline polyester resin. In addition, the constituent component and content ratio of each segment in the hybrid crystalline polyester resin can be specified by, for example, NMR measurement or methylation reaction P-GC/MS measurement.

<Amorphous polymerization segment>
The amorphous polymerized segment refers to a portion derived from an amorphous resin. That is, it refers to a molecular chain having the same chemical structure as that of the amorphous resin. When the binder resin according to the present invention contains an amorphous resin, the amorphous polymerized segment can contribute to the affinity between the amorphous resin and the hybrid crystalline polyester resin. The fact that the hybrid crystalline polyester resin contains the amorphous polymerized segment can be confirmed by specifying the chemical structure using, for example, NMR measurement or methylation reaction P-GC/MS measurement.

  Further, the amorphous polymerized segment has no melting point and has a relatively high glass transition temperature (Tg) when a differential scanning calorimetry (DSC) is performed on a resin having the same chemical structure and molecular weight as the segment. It is a polymerized segment.

  The content of the amorphous polymerized segment in the hybrid crystalline polyester resin is preferably 2% by mass or more and 20% by mass or less, and more preferably 5% by mass or more and 10% by mass or less. With the above range, sufficient crystallinity can be imparted to the hybrid crystalline polyester resin.

  When the binder resin according to the present invention contains an amorphous resin, the amorphous polymerized segment is preferably composed of the same kind of resin as the amorphous resin. With such a form, the adhesion between the hybrid crystalline polyester resin and the amorphous resin that can be the matrix phase is further improved.

  Here, the “similar resin” means that the characteristic chemical bonds are commonly contained in the repeating units. Here, "characteristic chemical bond" is described in National Institute for Materials Science (NIMS) Substance/Material Database (http://polymer.nims.go.jp/PoLyInfo/guide/jp/term_polymer.html). "Polymer classification" of. That is, polyacryl, polyamide, polyanhydride, polycarbonate, polydiene, polyester, polyhaloolefin, polyimide, polyimine, polyketone, polyolefin, polyether, polyphenylene, polyphosphazene, polysiloxane, polystyrene, polysulfide, polysulfone, polyurethane, polyurea. Chemical bonds constituting polymers classified by 22 kinds of polyvinyl, other polymers in total are called "characteristic chemical bonds".

  Further, in the case where the resin is a copolymer, "the same type of resin" means that the monomer species having the above-mentioned chemical bond is a constitutional unit in the chemical structure of a plurality of monomer species constituting the copolymer. In this case, it means resins having common characteristic chemical bonds. Therefore, even if the characteristics shown by the resins themselves are different from each other or even if the molar component ratios of the monomer species constituting the copolymer are different from each other, as long as they have a characteristic chemical bond in common. Considered to be the same type of resin.

  For example, a resin (or a polymerized segment) formed by styrene, butyl acrylate and acrylic acid and a resin (or a polymerized segment) formed by styrene, butyl acrylate and methacrylic acid have at least a chemical bond constituting polyacrylic. As such, they are the same type of resin.

  The resin component that constitutes the amorphous polymerized segment is not particularly limited, and examples thereof include a vinyl polymerized segment, a urethane polymerized segment, and a urea polymerized segment. Of these, vinyl polymerized segments are preferable because the thermoplasticity can be easily controlled.

  The vinyl polymerization segment is not particularly limited as long as it is obtained by polymerizing a vinyl monomer, and examples thereof include an acrylic acid ester polymerization segment, a styrene-acrylic acid ester polymerization segment, and an ethylene-vinyl acetate polymerization segment. These may be used alone or in combination of two or more.

  Among the above vinyl polymerized segments, a styrene-acrylic acid ester polymerized segment (styrene acrylic polymerized segment) is preferable in consideration of plasticity during heat fixing. Therefore, the styrene acrylic polymer segment as the amorphous polymer segment will be described below.

The styrene acrylic polymer segment is formed by addition-polymerizing at least a styrene monomer and a (meth)acrylic acid ester monomer. The styrene monomer mentioned here includes, in addition to styrene represented by the structural formula of CH ₂ ═CH—C ₆ H ₅ , those having a known side chain or functional group in the styrene structure. Further, the (meth)acrylic acid ester monomer referred to here is an acrylic acid ester compound represented by CH ₂ ═CHCOOR (R is an alkyl group) or a methacrylic acid ester compound, as well as an acrylic acid ester derivative or methacrylic acid ester. It includes an ester compound having a known side chain or functional group in the structure such as an acid ester derivative.

  The specific examples of the styrene monomer and the (meth)acrylic acid ester monomer capable of forming the styrene acrylic polymer segment are shown below, but those usable for forming the styrene acrylic polymer segment used in the present invention Is not limited to the following.

  First, as specific examples of the styrene monomer, for example, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4- Examples thereof include dimethyl styrene, p-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene and pn-dodecyl styrene. These styrene monomers can be used alone or in combination of two or more.

  Further, specific examples of the (meth)acrylic acid ester monomer include, for example, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate. Acrylic acid ester monomers such as stearyl acrylate, lauryl acrylate and phenyl acrylate; methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, Examples thereof include methacrylic acid esters such as stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate and dimethylaminoethyl methacrylate. Of these, it is preferable to use an acrylic acid ester monomer. Specifically, methyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate are preferable.

  These acrylic acid ester monomers or methacrylic acid ester monomers can be used alone or in combination of two or more. That is, a copolymer is formed by using a styrene monomer and two or more kinds of acrylic acid ester monomers, and a copolymer is formed by using a styrene monomer and two or more kinds of methacrylic acid ester monomers. It is possible to form a combination or to form a copolymer by using a styrene monomer and an acrylic acid ester monomer and a methacrylic acid ester monomer in combination.

  The content of the structural unit derived from the styrene monomer in the amorphous polymerized segment is preferably 40 to 90 mass% with respect to the total amount of the amorphous polymerized segment. Further, the content of the constituent unit derived from the (meth)acrylic acid ester monomer in the amorphous polymerized segment is preferably 10 to 60 mass% with respect to the total amount of the amorphous polymerized segment.

  Further, the amorphous polymerized segment is preferably formed by addition-polymerizing a compound for chemically bonding to the crystalline polyester polymerized segment, in addition to the styrene monomer and the (meth)acrylic acid ester monomer. Specifically, it is preferable to use a compound contained in the crystalline polyester polymerized segment and forming an ester bond with a hydroxyl group [-OH] derived from a polyhydric alcohol component or a carboxy group [-COOH] derived from a polycarboxylic acid component. . Therefore, the amorphous polymerized segment is addition-polymerizable with the styrene monomer and the (meth)acrylic acid ester monomer and has a carboxy group [—COOH] or a hydroxyl group [—OH]. It is preferable that the compound is further polymerized.

  Examples of such compounds include compounds having a carboxy group such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumaric acid, maleic acid monoalkyl ester, itaconic acid monoalkyl ester; 2-hydroxy. Ethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate And a compound having a hydroxyl group such as polyethylene glycol mono(meth)acrylate.

  The content of the structural unit derived from the above compound in the amorphous polymerized segment is preferably 0.5 to 20 mass% with respect to the total amount of the amorphous polymerized segment.

  The method for forming the styrene acrylic polymer segment is not particularly limited, and examples thereof include a method of polymerizing a monomer using a known oil-soluble or water-soluble polymerization initiator. Specific examples of the oil-soluble polymerization initiator include azo-based or diazo-based polymerization initiators and peroxide-based polymerization initiators shown below.

  Examples of the azo or diazo polymerization initiator include 2,2′-azobis-(2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile and 1,1′-azobis(cyclohexane-1). -Carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobisisobutyronitrile and the like.

  As the peroxide type polymerization initiator, benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxy carbonate, cumene hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide, dicumyl peroxide, 2, 4-dichlorobenzoyl peroxide, lauroyl peroxide, 2,2-bis-(4,4-t-butylperoxycyclohexyl)propane, tris-(t-butylperoxy)triazine and the like can be mentioned.

  Further, when the resin particles are formed by the emulsion polymerization method, a water-soluble radical polymerization initiator can be used. Examples of the water-soluble radical polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate, azobisaminodipropaneacetate, azobiscyanovaleric acid and its salts, and hydrogen peroxide.

  The weight average molecular weight (Mw) of the hybrid crystalline polyester resin is preferably 5,000 to 100,000, more preferably 7,000 to 50,000, and further preferably 8,000 to 40,000. preferable. The number average molecular weight (Mn) is preferably 100 to 50,000, and more preferably 1,000 to 10,000.

  The melting point (Tm) of the hybrid crystalline polyester resin is preferably 40 to 95°C, more preferably 50 to 85°C.

(Method for producing hybrid crystalline polyester resin)
The method for producing a hybrid crystalline polyester resin contained in the binder resin according to the present invention can form a polymer having a structure in which the crystalline polyester polymerized segment and the amorphous polymerized segment are chemically bonded. The method is not particularly limited. Specific methods for producing the hybrid crystalline polyester resin include, for example, the following methods.

(A) A method of producing a hybrid crystalline polyester resin by preliminarily polymerizing an amorphous polymerized segment and performing a polymerization reaction to form a crystalline polyester polymerized segment in the presence of the amorphous polymerized segment. First, an amorphous polymerized segment is formed by an addition reaction of a monomer (preferably a vinyl monomer such as a styrene monomer and a (meth)acrylic acid ester monomer) that constitutes the above-mentioned amorphous polymerized segment. To form. Next, in the presence of the amorphous polymerized segment, the polycarboxylic acid and the polyhydric alcohol are polymerized to form a crystalline polyester polymerized segment. At this time, a polycondensation carboxylic acid and a polyhydric alcohol are subjected to a condensation reaction, and a polyvalent carboxylic acid or a polyhydric alcohol is added to the amorphous polymerization segment to form a hybrid crystalline polyester resin. ..

  In the above method, it is preferable that the crystalline polyester polymerized segment or the amorphous polymerized segment has a site in which these segments can react with each other. Specifically, at the time of forming the amorphous polymerized segment, in addition to the monomer constituting the amorphous polymerized segment, a carboxy group [—COOH] or a hydroxyl group [—OH] remaining in the crystalline polyester polymerized segment. A compound having a site capable of reacting with and a site capable of reacting with the amorphous polymerized segment is also used. That is, when this compound reacts with the carboxy group [—COOH] or the hydroxyl group [—OH] in the crystalline polyester polymerized segment, the crystalline polyester polymerized segment can be chemically bonded to the amorphous polymerized segment. it can.

  Alternatively, a compound having a site capable of reacting with a polyhydric alcohol or a polycarboxylic acid and having a site capable of reacting with an amorphous polymer segment at the time of forming the crystalline polyester polymer segment may be used.

  By using the above method, a hybrid crystalline polyester resin having a structure (graft structure) in which a crystalline polyester polymerized segment is chemically bonded to an amorphous polymerized segment can be formed.

  The method (a) is preferable because it is easy to form a hybrid crystalline polyester resin having a structure in which a crystalline polyester polymer segment is grafted to an amorphous polymer segment, and the production process can be simplified. Further, in the method (a), since the amorphous polyester polymer segment is formed in advance and then the crystalline polyester polymer segment is bonded, the orientation of the crystalline polyester polymer segment is likely to be uniform. Therefore, the hybrid crystalline polyester resin suitable for the toner specified in the present invention can be reliably formed, which is preferable.

  Alternatively, (b) a crystalline polyester polymerized segment and an amorphous polymerized segment may be formed respectively, and these may be bonded to each other to produce a hybrid crystalline polyester resin, or (c) crystallinity A method of producing a hybrid crystalline polyester resin by forming a polyester polymer segment in advance and then performing a polymerization reaction to form an amorphous polymer segment in the presence of the crystalline polyester polymer segment may be used.

  By using the above method, a hybrid crystalline polyester resin having a structure (graft structure) in which a crystalline polyester polymerized segment is chemically bonded to an amorphous polymerized segment can be formed.

  As the preferable range of the melting point and the ester group concentration of the hybrid crystalline polyester resin, the preferable range described in the above crystalline polyester resin is applied as it is.

[Structure of toner]
The toner of the present invention preferably has a domain matrix structure. Generally, the breakage of the resin occurs in the flow in which crazes (cracks) occur, and then cracks occur and the resin breaks. The presence of discontinuities in the resin can stop crazes (also known as local stress relief). Since the toner has a domain matrix structure, the domains become discontinuous portions, and local stress can be relaxed, the image becomes more difficult to crack, and image peeling at the folded portion is further suppressed.

  In the present invention, the domain phase is preferably a crystalline polyester resin and the matrix phase is preferably an amorphous resin. By incorporating the crystalline polyester resin into the inside of the amorphous resin, the surface of the toner particles obtained does not have the crystalline polyester resin or the amount thereof is extremely small, resulting in charging Long-term stability of performance is obtained.

  On the other hand, when the affinity between the amorphous resin and the crystalline polyester resin is relatively low, it may be difficult for the crystalline polyester resin to be taken into the amorphous resin during toner production.

  Therefore, in the present invention, a core-shell in which an amorphous resin (hereinafter, also referred to as "coating resin") is attached to the surface of particles of the crystalline polyester resin (hereinafter, also referred to as "crystalline polyester resin particles") It is preferable to form toner particles by aggregating and fusing composite particles having a structure and particles of an amorphous resin (hereinafter, also referred to as “main resin”). Since the crystalline polyester resin and the amorphous resin are not easily compatible with each other, it is difficult for the crystalline polyester resin and the amorphous resin to stick to each other during the production of the toner particles, and the crystalline polyester resin in which the amorphous resin forming the matrix phase is contained in the domain phase is easily ejected. .. However, when the core particles contained in the domain phase are coated with the coating resin which is an amorphous resin, the domain phase and the matrix phase are easily made compatible with each other, and the adhesion between the domain phase and the matrix phase is improved, and further It becomes easier for the local stress to be relaxed.

  That is, in a preferred embodiment of the present invention, the domain phase of the domain matrix structure has a core shell composed of a core particle containing a crystalline resin and a shell part containing an amorphous resin coating the surface of the core particle. Includes structured composite particles. Further, the crystalline resin is preferably a crystalline polyester resin. The inclusion of the core-shell structured composite particles can be observed by observing the cross section of the osmium-stained toner particles by a conventional method using a transmission electron microscope. When cutting out the toner particle slices with an ultramicrotome, the thickness of the slices is set to 100 nm.

  Here, the "core-shell structure" may be not only a form in which the shell layer completely covers the core particles but also a part in which the core particles are covered. Further, a part of the shell resin forming the shell layer may form a domain or the like in the core particle. Further, the shell layer may have a multilayer structure of two or more layers containing resins having different compositions.

  Hereinafter, a method for producing composite particles in which the core particles are the crystalline polyester resin and the shell portion is the amorphous resin will be specifically described.

  The composite particles can be produced, for example, by utilizing a seed polymerization method. Specifically, a crystalline polyester resin particle is used as a seed, and a vinyl monomer is seed-polymerized on the surface of the crystalline polyester resin particle to form a core shell in which the surface of the crystalline polyester resin particle is coated with an amorphous resin. A composite particle of structure is obtained.

  In a preferred embodiment of the present invention, the amorphous resin (main resin) forming the matrix phase and the amorphous resin (coating resin) coating the surface of the crystalline polyester resin particles are the same type of monomer. It is preferably formed by using. In this way, the main resin and the coating resin are formed by using the same monomer, so that the affinity between the main resin and the coating resin can be made higher, and the crystalline polyester can be manufactured during the toner production. The resin can be introduced into the amorphous resin more efficiently.

  In the composite particles, the mass ratio of the crystalline polyester resin as the seed resin and the amorphous resin (coating resin) (crystalline polyester resin/coating resin) is preferably 10/90 to 80/20, 50 It is more preferably /50 to 80/20. When the mass ratio (crystalline polyester resin/coating resin) is in the above range, a sufficient amount of the coating resin is attached to the surface of the crystalline polyester resin particles, and the resulting composite particles have a good core-shell structure. Can be formed.

  In the above preferred embodiment, the surface of the crystalline polyester resin particles as seeds is preferably a composite particle in which the surface is completely covered with the coating resin, but a part of the surface of the crystalline polyester resin particles is non-coated. It may be a composite particle coated with a crystalline resin. Further, the coating resin may have a multilayer structure of two or more layers containing amorphous resins having different compositions.

  In a preferred embodiment, the matrix phase preferably contains an amorphous resin having a carboxy group. The inclusion of the amorphous resin having a carboxy group in the matrix phase facilitates the presence of polarized carboxy groups on the surface of the toner particles. Then, at the time of fixing, hydrogen bonds due to the carboxy groups between the toner particles come to work, and the adhesiveness between the toner particles is further improved. It is considered that this increases the adhesiveness at the toner particle interface, making it more difficult for image peeling to occur at the folded portion.

  The carboxy group concentration of the amorphous resin contained in the matrix phase is preferably 0.2 mmol/g or more and 1.0 mmol/g or less, and more preferably 0.3 mmol/g or more and 0.85 mmol/g or less. preferable. Here, the carboxy group concentration is the ratio of carboxy groups in the amorphous resin, and when the carboxy group concentration of the amorphous resin is in the above range, the adhesion between toner particles becomes stronger, and the folded portion The occurrence of peeling of the image is further suppressed. Further, it is possible to suppress the occurrence of a jam when passing a sheet.

  In the present invention, the carboxy group concentration is a value calculated by the following mathematical formula (B).

Formula (B): Carboxy group concentration=[mol number of carboxy groups/(sum of molecular weight of vinyl monomer forming amorphous resin×mol fraction)]×1000
The carboxy group concentration of the amorphous resin can be controlled by the content ratio of the monomer having a carboxy group.

  When two or more kinds of amorphous resins having different carboxy group concentrations are used as the amorphous resin, the carboxy group concentration is the content ratio (mass ratio) to the carboxy group concentration of each amorphous resin. ) Is the sum of values multiplied by.

The carboxy group concentration of the amorphous resin can be confirmed by, for example, ¹³ C-NMR (nuclear magnetic resonance) measurement using deuterated chloroform. Specifically, the peaks of carbon atoms derived from each monomer can be assigned to specify and calculate the monomer species and composition ratio.

  The carboxy group concentration of the coating resin and the carboxy group concentration of the binder resin are also preferably 0.2 mmol/g or more and 1.0 mmol/g or less, and are 0.3 mmol/g or more and 0. It is more preferably 85 mmol/g or less.

  The content of the amorphous resin (binder resin other than the crystalline polyester resin) is as described above. That is, the mass ratio of the binder resin other than the crystalline polyester resin and the crystalline polyester resin (the binder resin other than the crystalline polyester resin/the crystalline polyester resin) is preferably 97/3 to 60/40. , 95/5 to 70/30 is more preferable. Within this range, image peeling at the folded portion is further suppressed.

  As described above, when the amorphous resin is used for the coating resin and the matrix phase, the total amount thereof may be within the above preferable range.

  In the toner of the present invention, the binder resin may contain another resin such as an amorphous polyester resin in addition to the amorphous resin and the crystalline polyester resin described above.

〔Release agent〕
The toner of the present invention may contain a release agent.

  Specific examples of the release agent include polyolefin waxes such as polyethylene wax and polypropylene wax; branched hydrocarbon waxes such as microcrystalline wax; long-chain hydrocarbon waxes such as paraffin wax and sazol wax. A dialkyl ketone wax such as distearyl ketone; carnauba wax, montan wax, behenyl behenate, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, Ester waxes such as 1,18-octadecanediol distearate, tristearyl trimellitate and distearyl maleate; amide waxes such as ethylenediamine behenylamide and trimellitic acid tristearylamide.

  Among these, from the viewpoint of releasability at low temperature fixing, it is preferable to use one having a low melting point, specifically, one having a melting point of 40 to 90°C.

  The content of the release agent in the toner particles is preferably 1 to 20% by mass, more preferably 5 to 20% by mass. When the content ratio of the release agent in the toner particles is within the above range, the separability and the fixability are surely compatible with each other.

[Colorant]
The toner of the present invention may contain a colorant. Examples of the colorant include carbon black, black iron oxide, dyes and pigments.

  Examples of carbon black include channel black, furnace black, acetylene black, thermal black, lamp black, and the like, and examples of black iron oxide include magnetite, hematite, titanium iron trioxide, and the like.

  Examples of the dye include C.I. I. Solvent Red 1, 49, 52, 58, 63, 111, 122, C.I. I. Solvent Yellow 19, the same 44, the same 77, the same 79, the same 81, the same 82, the same 93, the same 98, the same 103, the same 104, the same 112, the same 162, C.I. I. Solvent Blue 25, the same 36, the same 60, the same 70, the same 93, the same 95 and the like.

  Examples of the pigment include C.I. I. Pigment Red 5, Same 48:1, Same 48:3, Same 53:1, Same 57:1, Same 81:4, Same 122, Same 139, Same 144, Same 149, Same 150, Same 166, Same 177, 178, 222, 238, 269, C.I. I. Pigment Orange 31, the same 43, C.I. I. Pigment Yellow 14, the same 17, the same 74, the same 93, the same 94, the same 138, the same 155, the same 156, the same 158, the same 180, the same 185, C.I. I. Pigment Green 7, C.I. I. Pigment Blue 15:3, 60 and the like.

  The colorant for obtaining the toner of each color can be used alone or in combination of two or more for each color.

  The content ratio of the colorant in the toner particles is preferably 1 to 10% by mass, and more preferably 2 to 8% by mass. Within this range, a desired coloring power can be imparted to the obtained toner, the release of the coloring agent and the adhesion to the carrier can be suppressed, and the chargeability can be maintained.

(Charge control agent)
The toner particles of the present invention may contain a charge control agent.

  As the charge control agent, various known compounds such as nigrosine dye, metal salt of naphthenic acid or higher fatty acid, alkoxylated amine, quaternary ammonium salt compound, azo metal complex, metal salt of salicylic acid can be used. .

  The charge control agent is added in an amount of usually 0.1 to 10 parts by mass, preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the binder resin in the finally obtained toner particles.

When the toner of the present invention has a domain matrix structure, it is particularly preferable that the matrix contains a charge control agent from the viewpoint of dispersibility of the charge control agent [external additive].
In the toner of the present invention, the toner particles can be used as a toner as they are, but in order to improve fluidity, charging property, cleaning property and the like, so-called fluidizing agents, cleaning aids, etc. are added to the toner particles. External additives may be added. The type of external additive is not particularly limited, and examples thereof include known inorganic particles and lubricants exemplified below. These external additives may be used alone or in combination of two or more.

  As the inorganic particles, conventionally known particles can be used, and for example, silica, titania (titanium dioxide), alumina, strontium titanate particles, hydrotalcite and the like are preferable. Further, if necessary, those obtained by subjecting these inorganic particles to a hydrophobic treatment can also be used.

  As the lubricant, there are the following metal salts of higher fatty acids. That is, salts of stearic acid such as zinc, aluminum, copper, magnesium and calcium, salts of oleic acid such as zinc, manganese, iron, copper and magnesium, palmitic acid such as zinc, salts of copper, magnesium and calcium, and linoleic acid. And salts of ricinoleic acid such as zinc and calcium.

  The addition amount of the external additive (when two or more kinds are used, the total amount) is preferably 0.05 to 5 parts by mass, more preferably 0.1 to 3 parts by mass with respect to 100 parts by mass of the toner base particles. Is.

[Particle size of toner particles]
In the toner particles according to the present invention, the average particle diameter is, for example, preferably 3 to 8 μm in volume-based median diameter, and more preferably 5 to 8 μm. This average particle size can be controlled by the concentration of the aggregating agent used during production, the amount of the organic solvent added, the fusion time, the composition of the binder resin, and the like. When the volume-based median diameter is within the above range, it is possible to faithfully reproduce a very fine dot image of 1200 dpi level.

  The volume-based median diameter of toner particles is measured using a measuring device in which a computer system equipped with "Multisizer 3" (manufactured by Beckman Coulter, Inc.) and data processing software "Software V3.51" is connected. It is calculated. Specifically, 0.02 g of a measurement sample (toner) was used as a surfactant solution 20 mL (for the purpose of dispersing toner particles, for example, a neutral detergent containing a surfactant component was diluted 10 times with pure water. Solution) and acclimated to it, ultrasonic dispersion is carried out for 1 minute to prepare a toner dispersion liquid, and this toner dispersion liquid is put in "ISOTONII" (manufactured by Beckman Coulter, Inc.) in a sample stand. Pipette into the beaker until the indicated concentration on the measuring device is 8%. Here, by setting this concentration range, reproducible measurement values can be obtained. Then, in the measuring device, the number of particles to be measured was set to 25,000, the aperture diameter was set to 100 μm, and the frequency value was calculated by dividing the range of 2 to 60 μm, which is the measurement range, into 256. The particle size of% is the volume-based median size.

[Average circularity of toner particles]
In the toner of the present invention, the average circularity of individual toner particles constituting the toner is preferably 0.920 to 1.000, from the viewpoints of stability of charging characteristics and low-temperature fixability. More preferably, it is 930 to 0.995. When the average circularity is in this range, individual toner particles are less likely to be crushed, the contamination of the frictional charge imparting member is suppressed, the chargeability of the toner is stabilized, and the image quality of the formed image is high. Becomes

  The average circularity of the toner is a value measured using "FPIA-2100" (manufactured by Sysmex). Specifically, the measurement sample (toner) is soaked in an aqueous solution containing a surfactant, ultrasonic dispersion treatment is performed for 1 minute to disperse the sample, and then the measurement condition HPF is measured by "FPIA-2100" (manufactured by Sysmex). In the (high-magnification imaging) mode, the HPF detection number is photographed at an appropriate density of 3,000 to 10,000, and the circularity of each toner particle is calculated according to the following formula (y), and the circularity of each toner particle is calculated. Is a value calculated by adding the degrees and dividing by the total number of toner particles. If the number of HPF detections is within the above range, reproducibility can be obtained.

  Formula (y): Circularity=(perimeter of circle having the same projected area as the particle image)/(perimeter of particle projected image).

[Softening point]
The softening point of the toner of the present invention is 115° C. or lower. When the softening point exceeds 115° C., the low temperature fixability of the toner deteriorates. The softening point of the toner is preferably 110° C. or lower. On the other hand, the lower limit of the softening point is not particularly limited, but is preferably 80°C or higher, more preferably 90°C or higher.

In the present invention, the softening point of the toner is measured by a flow tester. Specifically, first, in an environment of 20° C. and 50% RH, 1.1 g of the sample (toner) is put into a Petri dish and flattened, and left for 12 hours or more, and then the molding machine “SSP-10A” (stock (Made by Shimadzu Corporation) is pressed with a force of 3820 kg/cm ² for 30 seconds to produce a cylindrical molded sample having a diameter of 1 cm, and then this molded sample is subjected to a flow tester in an environment of 24° C. and 50% RH. With a “CFT-500D” (manufactured by Shimadzu Corporation), a hole (1 mm diameter×1 mm diameter) of a cylindrical die was formed under the conditions of a load of 196 N (20 kgf), a starting temperature of 60° C., a preheating time of 300 seconds, and a heating rate of 6° C./min. 1 mm), the offset method temperature T _{offset, which} is extruded from the end of preheating using a piston having a diameter of 1 cm and measured with the offset value of 5 mm by the melting temperature measuring method of the temperature rising method, is taken as the softening point.

  The softening point of the toner is controlled by adjusting the kind and addition amount of the monomer used for the resin that constitutes the binder resin, the molecular weight of the resin, and the content ratio of the binder resin if there are multiple resins. can do.

[Critical load]
In the toner of the present invention, a sapphire needle having a tip diameter of 50 μm is used, and a scratch test of an image surface by a toner formed on a glass substrate with an adhesion amount of 16 g/m ² is performed by a load variation type friction wear tester. The critical load is 30 gf or more. When the critical load is less than 30 gf, the image strength is low and the image peeling at the folded portion is more likely to occur. The critical load is preferably 50 gf or more and 150 gf or less, more preferably 50 gf or more and 120 gf or less. The upper limit of the critical load is not particularly limited, but is usually 400 gf or less.

  The critical load is the kind and addition amount of the monomer used in the resin constituting the binder resin, the molecular weight of the resin, the carboxy group concentration and the ester group concentration of the resin, and if there are plural resins constituting the binder resin, It can be controlled by adjusting the content ratio and the like. The critical load can be measured by the following method.

<Measurement method of critical load>
As an image forming apparatus, a commercially available copying machine “bizhub PRO (registered trademark) C6550” (manufactured by Konica Minolta Co., Ltd.) was developed and transferred directly from the developing sleeve onto the glass substrate, and developed so that a thick glass substrate could pass through. It is modified so that the distance from the sleeve to the side of development and transfer can be changed, and the paper path is modified so that the glass substrate does not deform. A slide glass (manufactured by AS ONE CORPORATION, model number 10117102, cutting type, surface treatment) that is loaded with a developer containing toner and is kept at normal temperature and humidity (temperature 20° C., humidity 50% RH) environment so as not to touch the surface. A solid image having a toner adhesion amount of 16 g/m ² is fixed on the sheet. More specifically, in a commercially available copying machine "bizPRO PRO (registered trademark) C6550" as an image fixing device, the surface temperature of the fixing heating roller in the fixing unit of the heat roller fixing system is evaluated by a separate low temperature fixing property evaluation (implementation). The minimum fixing temperature obtained in the example method) +25° C., the rotation speed of the heat roller was modified so that the fixing time was 4 seconds, and the pressure of the heat roller was 200 kPa, and Use a paper passage modified so that the glass substrate does not deform. Using such an image fixing device, a developer containing a toner is mounted on the image fixing device, and the slide glass not subjected to the above surface treatment is placed in a room temperature and normal humidity (temperature 20° C., humidity 50% RH) environment. A solid image having a toner adhesion amount of 16 g/m ² is fixed.

  Using a load variation type friction wear tester shown below, a load variation type scratch test is carried out using a sapphire terminal having a tip diameter of 50 μm. In the load-variable scratch test, the load increases as the scratching distance increases, and the starting load can be changed depending on the position where the glass substrate is installed. From the change in torque, the critical load (the load when the separation of the solid image starts) can be determined, and the critical load can also be determined by observing the peeling state of the scratched portion. In this evaluation, the critical load is measured by the change in torque.

  If the horizontal axis is the load and the vertical axis is the torque applied to the terminal, and the relationship is plotted in a graph, the gradient of the change in torque is less than 15 mN/g when the terminal passes over the toner image. When peeling starts, the gradient of change in torque becomes 15 mN/g or more. Therefore, when the load is increased, the load at which the inclination becomes 15 mN/g or more for the first time is set as the critical load.

Equipment: HEIDON Tribogear 18L Scratch Strength Tester (Shinto Kagaku Co., Ltd.)
Terminal: Sapphire needle Tip diameter 50μm
Load increase rate: 200g/min
Scratch speed: 200 mm/min.

  When the HEIDON Tribogear 18L scratch strength tester is used, the scratch test can be performed even if a load of 200 g or more is used by modifying the sample installation part.

[Developer]
The toner of the present invention may be used as a magnetic or non-magnetic one-component developer, or may be mixed with a carrier and used as a two-component developer. When the toner is used as a two-component developer, the carrier may be magnetic particles made of a conventionally known material such as metals such as iron, ferrite and magnetite, and alloys of those metals with metals such as lead and lead. It can be used, and ferrite particles are particularly preferable. As the carrier, a coated carrier in which the surface of magnetic particles is coated with a coating agent such as silicone resin, or a dispersion type carrier in which fine magnetic powder is dispersed in a binder resin may be used.

  The volume-based median diameter of the carrier is preferably 20 to 100 μm, and more preferably 25 to 80 μm. The volume-based median diameter of the carrier can be typically measured by a laser diffraction particle size distribution analyzer “HELOS” (manufactured by SYMPATEC) equipped with a wet disperser.

[Method of manufacturing toner for developing electrostatic latent image]
The method for producing the toner of the present invention is not particularly limited, but includes a wet production method produced in an aqueous medium, for example, an emulsion aggregation method.

  The method for producing a toner of the present invention by an emulsion aggregation method is a method in which particles of a binder resin (hereinafter, also referred to as “binder resin particles”) are dispersed in an aqueous medium, and particles of a colorant (hereinafter, referred to as “colorant particles”). , Also referred to as "colorant particles"), and the binder resin particles and the colorant particles are aggregated and heat-fused to form toner particles to prepare a toner.

  The binder resin particles may have a multi-layer structure of two or more layers made of binder resins having different compositions, and the binder resin particles having such a structure are usually those having a two-layer structure. A dispersion of resin particles is prepared by a polymerization treatment (first stage polymerization) according to the method, a polymerization initiator and a polymerizable monomer are added to this dispersion, and this system is subjected to a polymerization treatment (second stage polymerization). ) Can be obtained.

  Here, the "aqueous dispersion liquid" refers to a dispersion (particles) dispersed in an aqueous medium, and the aqueous medium refers to a liquid whose main component (50% by mass or more) is water. .. Examples of components other than water include organic solvents that are soluble in water, and examples thereof include methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, and tetrahydrofuran. Of these, alcohol-based organic solvents such as methanol, ethanol, isopropanol, and butanol, which are organic solvents that do not dissolve the resin, are particularly preferable.

Concretely showing an example of the method for producing the toner of the present invention,
(A) a step of preparing an aqueous dispersion liquid in which particles of an amorphous resin (hereinafter, also referred to as “resin particles”) are dispersed in an aqueous medium,
(B) A vinyl monomer is added to an aqueous dispersion obtained by dispersing crystalline polyester resin particles (hereinafter, also referred to as “crystalline polyester resin particles”) in an aqueous medium to obtain crystalline polyester resin particles. By performing seed polymerization with a vinyl monomer as a seed, the composite particles in which the amorphous resin (hereinafter, also referred to as “amorphous resin for surface layer”) is attached to the surface of the crystalline polyester resin particles are dispersed. A step of preparing an aqueous dispersion comprising
(C) a step of preparing an aqueous dispersion liquid in which colorant particles are dispersed in an aqueous medium,
(D) a step of aggregating and fusing resin particles, composite particles and colorant particles in an aqueous medium to form associated particles,
(E) a step of aging the associated particles with thermal energy to control the shape to obtain toner particles, (f) a step of cooling the dispersion liquid of the toner particles,
(G) a step of filtering the toner particles from the aqueous medium and removing a surfactant or the like from the toner particles,
(H) Steps such as a step of drying the washed toner particles, and if necessary,
(I) A step of adding an external additive to the dried toner particles can be added.

(A) Preparation Step of Aqueous Dispersion of Resin Particles In this step, an aqueous dispersion of resin particles of an amorphous resin is prepared.

  The aqueous dispersion of resin particles can be prepared by a mini-emulsion polymerization method using a vinyl monomer for obtaining an amorphous resin. That is, for example, a vinyl monomer is added to an aqueous medium containing a surfactant, mechanical energy is applied to form droplets, and then the radicals from the water-soluble radical polymerization initiator cause the droplets in the droplets. In, the polymerization reaction proceeds. An oil-soluble polymerization initiator may be contained in the droplets. This makes it possible to prepare an aqueous dispersion of resin particles made of an amorphous resin.

[Surfactant]
As the surfactant used in this step, various conventionally known anionic surfactants, cationic surfactants, nonionic surfactants and the like can be used.

[Polymerization initiator]
As the polymerization initiator used in this step, various conventionally known ones can be used. As specific examples of the polymerization initiator, for example, persulfates (potassium persulfate, ammonium persulfate, etc.) are preferably used. In addition, using azo compounds (4,4′-azobis-4-cyanovaleric acid and salts thereof, 2,2′-azobis(2-amidinopropane) salt, etc.), peroxide compounds, azobisisobutyronitrile, etc. Good.

[Chain transfer agent]
In this step, a commonly used chain transfer agent can be used for the purpose of adjusting the molecular weight of the amorphous resin. The chain transfer agent is not particularly limited, and examples thereof include 2-chloroethanol, octyl mercaptan, n-octyl-3-mercaptopropionate, mercaptans such as dodecyl mercaptan and t-dodecyl mercaptan, and styrene dimer. be able to.

  In addition to the binder resin, the toner particles according to the present invention may optionally contain other internal additives such as a release agent and a charge control agent. Can be introduced into the toner particles by, for example, being dissolved or dispersed in advance in a solution of a vinyl monomer for forming the amorphous resin in this step.

  In addition, such an internal additive is prepared by separately preparing a dispersion liquid of the internal additive particles consisting of only the internal additive, and the internal additive particles together with the resin particles, the composite particles and the colorant particles in the aggregation/fusion step. Although it can be introduced into the toner particles by aggregating, it is preferable to adopt a method of introducing in advance in this step.

  The average particle diameter of the resin particles is preferably in the range of 20 to 400 nm in terms of volume-based median diameter. In the present invention, the volume-based median diameter of resin particles is a value measured using "Microtrac UPA-150" (manufactured by Nikkiso Co., Ltd.).

(B) Preparation Step of Aqueous Dispersion of Composite Particles In this step, the composite resin in which the coating resin (amorphous resin) formed by using the vinyl monomer is attached to the surface of the crystalline polyester resin particles An aqueous dispersion of is prepared.

  Specifically, an aqueous dispersion obtained by synthesizing a crystalline polyester resin (preferably a hybrid crystalline polyester resin) and dispersing the crystalline polyester resin in the form of fine particles in an aqueous medium to disperse the crystalline polyester resin particles. A liquid is obtained, and a vinyl monomer and a polymerization initiator are added to this aqueous dispersion, and seed polymerization is performed with the vinyl monomer using the crystalline polyester resin particles as seeds to prepare an aqueous dispersion of composite particles. can do.

  Aqueous dispersion of crystalline polyester resin particles, the crystalline polyester resin is dissolved or dispersed in an organic solvent to prepare an oil phase liquid, the oil phase liquid is dispersed in an aqueous medium by phase inversion emulsification, It can be prepared by forming oil droplets in a state of being controlled to have a desired particle size and then removing the organic solvent.

  The amount of the aqueous medium used is preferably 50 to 2,000 parts by mass, and more preferably 100 to 1,000 parts by mass with respect to 100 parts by mass of the oil phase liquid.

  A surfactant or the like may be added to the aqueous medium for the purpose of improving the dispersion stability of oil droplets. As the surfactant, the same ones as those mentioned in the above steps can be mentioned.

  As the organic solvent used for the preparation of the oil phase liquid, those having a low boiling point and low solubility in water are preferable from the viewpoint of easy removal treatment after formation of oil droplets, and specifically, Examples thereof include methyl acetate, ethyl acetate, methyl ethyl ketone, methyl isobutyl ketone, toluene and xylene. These may be used alone or in combination of two or more. The amount of the organic solvent used is usually 1 to 300 parts by mass with respect to 100 parts by mass of the crystalline polyester resin. The oil phase liquid can be emulsified and dispersed by utilizing mechanical energy.

  The average particle size of the crystalline polyester resin particles used as seeds is preferably in the range of 10 to 400 nm in terms of volume-based median diameter. In the present invention, the volume-based median diameter of the crystalline polyester resin particles is a value measured using "Microtrac UPA-150" (manufactured by Nikkiso Co., Ltd.).

  In the seed polymerization, a commonly used chain transfer agent can be used for the purpose of adjusting the molecular weight of the amorphous resin. As the chain transfer agent, the same ones as those mentioned in the above steps can be mentioned. As the polymerization initiator, the same ones as those mentioned in the above steps can be mentioned.

  The seed polymerization is preferably carried out in a state where the viscosity of the crystalline polyester resin is high, and the polymerization temperature of the seed polymerization is preferably the melting point of the crystalline polyester resin +20°C or lower, and the melting point +10°C or lower. Is more preferable, and it is more preferable that the melting point is not higher than the melting point.

  The average particle diameter of the composite particles is preferably in the range of 20 to 400 nm in terms of volume-based median diameter. In the present invention, the volume-based median diameter of the composite particles is a value measured using "Microtrac UPA-150" (manufactured by Nikkiso Co., Ltd.).

(C) Step of Preparing Aqueous Dispersion of Colorant Particles This step is a step that is carried out as necessary when toner particles containing a colorant are desired, and the colorant is a fine particle in an aqueous medium. Is a step of preparing an aqueous dispersion liquid of the colorant particles by dispersing in the.

  The aqueous dispersion of colorant particles can be obtained by dispersing the colorant in an aqueous medium containing a surfactant at a critical micelle concentration (CMC) or higher. Dispersion of the colorant can be performed by utilizing mechanical energy, and the disperser used is not particularly limited, but preferably an ultrasonic disperser, a mechanical homogenizer, a Manton-Gaulin or a pressure homogenizer. A medium type disperser such as a pressure disperser, a sand grinder, a Getzman mill or a diamond fine mill can be used.

  The colorant particles in the dispersed state have a volume-based median diameter of preferably 10 to 300 nm, more preferably 100 to 200 nm, and further preferably 100 to 150 nm. In the present invention, the volume-based median diameter of the colorant particles is a value measured using an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.).

(D) Aggregation/Fusion Step In this step, the resin particles, the composite particles and the colorant particles, and particles of other toner constituting components are agglomerated, and further fused by heating.

  Specifically, in an aqueous dispersion liquid in which the above particles are dispersed in an aqueous medium, a coagulant having a critical coagulation concentration or higher is added, and the temperature is set to a temperature equal to or higher than the glass transition point of the amorphous resin and the coating resin. To agglomerate and fuse.

  In this step, the resin particles, the colorant particles, and the composite particles may be mixed at once in the aqueous medium in a state below the glass transition point of the amorphous resin and the coating resin, or the resin particles and the colorant may be mixed. After adding the coagulant to the aqueous medium in which the particles are dispersed, the composite particles may be added without raising the temperature. Further, when the aggregated particles obtained by aggregating the resin particles and the colorant particles have a size of 1/4 to 1/2 of the particle size of the toner particles to be formed, the composite particles are added, and thereafter, The temperature may be raised above the glass transition point of the amorphous resin and the coating resin. By adding the composite particles at such a timing and subjecting them to aggregation, the composite particles can be more efficiently confined inside the toner particles to be formed.

[Flocculant]
The aggregating agent used in this step is not particularly limited, but one selected from metal salts such as alkali metal salts and salts of Group 2 metals is preferably used. Examples of the metal salt include monovalent metal salts such as sodium, potassium and lithium; divalent metal salts such as calcium, magnesium, manganese and copper; and trivalent metal salts such as iron and aluminum. Specific examples of the metal salt include sodium chloride, potassium chloride, lithium chloride, calcium chloride, magnesium chloride, zinc chloride, copper sulfate, magnesium sulfate, manganese sulfate and the like. It is particularly preferable to use a divalent metal salt because it can proceed. These may be used alone or in combination of two or more.

(E) Aging step This step is carried out as necessary. In the aging step, the associated particles obtained by the aggregating/fusing step are aged by heat energy until they have a desired shape. An aging treatment for forming toner particles is performed.

  The aging treatment is, specifically, by heating and stirring the system in which the associated particles are dispersed, and adjusting the shape of the associated particles by the heating temperature, stirring speed, heating time, etc. until the shape of the associated particles reaches a desired circularity. , Done.

(F) Cooling Step This step is a step of cooling the dispersion liquid of toner particles. As conditions for the cooling treatment, it is preferable to cool at a cooling rate of 1 to 20° C./min. The specific method of the cooling treatment is not particularly limited, and examples thereof include a method of cooling by introducing a refrigerant from the outside of the reaction vessel and a method of directly charging cold water into the reaction system for cooling. it can.

(G) Filtration/Washing Step In this step, the toner particles are solid-liquid separated from the cooled dispersion liquid of the toner particles, and a toner cake obtained by the solid-liquid separation (toner particles in a wet state is aggregated into a cake shape). This is a step of removing adhering substances such as a surfactant and an aggregating agent from the collected aggregate) and washing.

  The solid-liquid separation is not particularly limited, and a centrifugal separation method, a vacuum filtration method using a Nutsche or the like, a filtration method using a filter press or the like can be used. In the washing, it is preferable to wash with water until the electric conductivity of the filtrate becomes, for example, 15 μS/cm or less.

(H) Drying Step This step is a step of drying the washed toner cake, and can be performed according to the drying step in the generally known method for producing toner particles.

  Specifically, examples of the dryer used for drying the toner cake include a spray dryer, a vacuum freeze dryer, a vacuum dryer, a stationary shelf dryer, a mobile shelf dryer, and a fluidized bed. It is preferable to use a dryer, a rotary dryer, a stirring dryer or the like.

  The water content of the dried toner particles is preferably 5% by mass or less, and more preferably 2% by mass or less. When the dried toner particles are agglomerated with each other by a weak attractive force between particles, the agglomerate may be crushed. Here, as the crushing treatment device, a mechanical crushing device such as a jet mill, a Henschel mixer, a coffee mill, a food processor or the like can be used.

(I) Step of Adding External Additive This step is a step that is performed as necessary when adding an external additive to the toner particles.

  As a mixing device for the external additive, a mechanical mixing device such as a Henschel mixer or a coffee mill can be used.

  Although the embodiments of the present invention have been specifically described above, the embodiments of the present invention are not limited to the above examples, and various modifications can be made.

  For example, the toner of the present invention may be composed of toner particles having a core-shell structure composed of core particles containing a binder resin and a shell layer made of a shell resin coating the outer peripheral surface thereof. According to the toner having the shell layer thus formed, when the composite particles as described above are used as the binder resin, the crystalline polyester resin has a structure in which it is more difficult to be exposed on the surface of the toner particles. It is possible to further suppress deterioration of performance.

  Hereinafter, typical embodiments of the present invention will be shown and the present invention will be further described, but the present invention is not limited to these embodiments. In the examples, "parts" means "parts by mass" and "%" means "% by mass" unless otherwise specified.

  Measurement of molecular weight and melting point of hybrid crystalline polyester resin; measurement of volume-based median diameter of resin particles, colorant particles, crystalline polyester resin particles, and composite particles; carboxy group concentration of amorphous resin; crystallinity The ester group concentration of the polyester resin and the softening point of the toner were measured as described above.

[Preparation of toner]
[Preparation of Dispersion Liquid [A1] of Amorphous Resin (Vinyl Resin) Particles [a1] Containing Release Agent]
(First stage polymerization)
A solution prepared by dissolving 8 g of sodium dodecyl sulfate in 3 L of ion-exchanged water was charged into a 5 L reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introducing device. While stirring at a stirring rate of 230 rpm under a nitrogen stream, the internal temperature was raised to 85° C., then a solution of 10 g of potassium persulfate dissolved in 200 g of ion-exchanged water was added, and the liquid temperature was set to 85° C. again.
Styrene (St) 480g
n-Butyl acrylate (BA) 193 g
82 g of 2-ethylhexyl acrylate (2HEA)
Methacrylic acid (MAA) 38g
Polyethylene glycol diacrylate (PEDA) (n=9) 23g
After the monomer mixture consisting of the above was added dropwise over 1 hour, polymerization was carried out by heating and stirring at 85° C. for 2 hours to prepare an aqueous dispersion [A11] in which the resin particles [a11] were dispersed.

(Second-stage polymerization)
A 10 L reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introducing device was charged with a solution prepared by dissolving 7 g of sodium polyoxyethylene (2) dodecyl ether sulfate in 800 ml of ion-exchanged water, and heated to 98°C. Then, the entire amount of the aqueous dispersion liquid [A11] prepared above was added.

further,
Styrene (St) 137g
55 g of n-butyl acrylate (BA)
2-ethylhexyl acrylate (2HEA) 23 g
Methacrylic acid (MAA) 11g
Polyethylene glycol diacrylate (PEDA) (n=9) 7g
n-octyl-3-mercaptopropionate 1.0 g
Release agent: behenyl behenate (melting point 73°C) 190 g
Was dissolved and mixed at 90° C., and the monomer solution was mixed and dispersed for 1 hour by a mechanical disperser “Clearmix (registered trademark)” (manufactured by M Technique Co., Ltd.) having a circulation path to obtain emulsified particles ( A dispersion containing oil droplets) was prepared.

  Then, an initiator solution prepared by dissolving 6 g of potassium persulfate in 200 ml of ion-exchanged water was added to the reaction vessel, and the system was heated and stirred at 82° C. for 1 hour to perform polymerization, whereby resin particles [a12] were obtained. An aqueous dispersion liquid [A12] was prepared by dispersion.

(Third stage polymerization)
To the above aqueous dispersion [a12], a solution prepared by dissolving 11 g of potassium persulfate in 400 ml of ion-exchanged water was added, and a temperature condition of 82°C was added.
Styrene (St) 240g
97 g of n-butyl acrylate (BA)
2-ethylhexyl acrylate (2HEA) 41 g
Methacrylic acid (MAA) 19g
Polyethylene glycol diacrylate (PEDA) (n=9) 12g
n-octyl-3-mercaptopropionate 6 g
The monomer mixture consisting of was added dropwise over 1 hour. After completion of the dropwise addition, the mixture was heated and stirred for 2 hours to carry out polymerization, and then cooled to 28° C., whereby amorphous resin particles [a1] containing a vinyl monomer as a main component and a releasing agent. Aqueous dispersion [A1] was prepared.

  The volume-based median diameter of the amorphous resin particles [a1] of this aqueous dispersion [A1] was 200 nm.

[Preparation of dispersion liquids [A2] to [A10] of amorphous resin particles [a2] to [a10]
Aqueous dispersions [A2] to [A10] were prepared in the same manner as in the above dispersion [A1] except that the addition amount of each monomer was changed as shown in Table 1 below. In [A10], acrylic acid (AA) was used instead of 2-ethylhexyl acrylate. Table 1 below also shows the molar ratio of each monomer and the carboxy group concentration of the amorphous resin. Further, "-" in Table 1 indicates that the monomer was not used.

  The volume-based median diameters of the amorphous resin particles [a2] to [a10] and the weight average molecular weight of the amorphous resin were the same as in [A1].

[Preparation of Aqueous Dispersion Liquid [C1] of Hybrid Crystalline Polyester Resin Particles]
Synthesis of Hybrid Crystalline Polyester Resin (Hybrid CPES, c1) The following raw material monomers of addition polymerization type resin (styrene acrylic polymerization segment), both-reactive monomers and radical polymerization initiator were placed in a dropping funnel.

Styrene 34 parts by mass n-Butyl acrylate 12 parts by mass Acrylic acid 2 parts by mass Polymerization initiator (di-t-butyl peroxide) 7 parts by mass Further, the following raw material monomers for the polycondensation resin (crystalline polyester polymerization segment) are added, It was put in a four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer and a thermocouple, and heated to 170° C. to dissolve it.

Sebacic acid (Molecular weight 202.25) 300 parts by mass 1,6-hexanediol (Molecular weight 118.17) 196 parts by mass Then, the raw material monomer of the addition polymerization type resin is added dropwise over 90 minutes with stirring, and aged for 60 minutes. After that, the unreacted addition-polymerized monomer was removed under reduced pressure (8 kPa). At this time, the amount of the removed monomer was very small with respect to the raw material monomer of the resin.

Then, 0.8 parts by mass of Ti(O-n-Bu) ₄ was added as an esterification catalyst, the temperature was raised to 235° C., normal pressure (101.3 kPa) for 5 hours, and further reduced pressure (8 kPa). The reaction was carried out for 1 hour. Next, after cooling to 200° C., a hybrid crystalline polyester resin (c1) was obtained by reacting under reduced pressure (20 kPa) for 1 hour. The weight average molecular weight (Mw) of the obtained hybrid crystalline polyester resin (c1) was 14,000, and the melting point (Tm) was 66.8°C.

30 parts by mass of the hybrid crystalline polyester resin (c1) was transferred in a molten state to an emulsification disperser “Cavitron CD1010” (manufactured by Eurotech Co., Ltd.) at a transfer rate of 100 parts by mass per minute. Simultaneously with the transfer of the melted hybrid crystalline polyester resin (c1), 70 parts by mass of reagent ammonia water was diluted with ion-exchanged water in an aqueous solvent tank for the emulsification disperser. Dilute aqueous ammonia having a concentration of 0.37 mass% was transferred at a transfer rate of 0.1 liters per minute while being heated to 100° C. by a heat exchanger. By operating this emulsification disperser under the conditions of a rotor rotation speed of 60 Hz and a pressure of 5 kg/cm ² , hybrid crystalline polyester resin particles having a volume-based median diameter of 200 nm and a solid content of 30% by mass ( An aqueous dispersion [C1] of c1) was prepared.

[Preparation of Aqueous Dispersion Liquid [C2] to [C6] of Hybrid Crystalline Polyester Resin Particles]
Hybrid crystals were prepared in the same manner as in [Preparation of Aqueous Dispersion of Hybrid Crystalline Polyester Resin Particles [C1]] except that the type and addition amount of the raw material monomer of the polycondensation resin were changed as shown in Table 2 below. Aqueous dispersions [C2] to [C6] of the hydrophilic polyester resin particles (c2) to (c6) were prepared. In addition, in (c2) to (c6), the weight average molecular weight and the volume-based median diameter in the dispersion were all the same as (c1).

[Preparation of Aqueous Dispersion of Crystalline Polyester Resin Particles [C7]]
Except that the raw material monomer of the addition polymerization resin is not used and the type and the addition amount of the raw material monomer of the polycondensation resin are changed as shown in Table 2 below, the above [aqueous dispersion of hybrid crystalline polyester resin particles [ C1]], an aqueous dispersion [C7] of crystalline polyester resin particles (CPES, c7) was prepared. The weight average molecular weight (Mw) of (c7) was 35,000, and the volume-based median diameter in the dispersion was 200 nm.

  Table 2 below shows the monomer type and addition amount of each hybrid crystalline polyester resin and crystalline polyester resin, the ester group concentration, and the melting point.

[Preparation of Aqueous Dispersion of Composite Particles [S1]]
In a 5 L reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introducing device, 2000 parts by mass of an aqueous dispersion [C1] of hybrid crystalline polyester resin particles (c1) as seeds and 1150 parts by mass of ion-exchanged water. And 10.3 parts by mass of potassium persulfate were dissolved in 210 parts by mass of deionized water, and a polymerization initiator solution was added. Under a temperature condition of 85° C., as vinyl monomers forming the coating resin, 390 parts by mass of styrene (St), 143 parts by mass of n-butyl acrylate (BA), 58 parts by mass of 2-ethylhexyl acrylate (2HEA) and polyethylene. A monomer mixture consisting of 60 parts by mass of glycol diacrylate (PEDA) (n=9) and 30 parts by mass of methacrylic acid (MMA) was added dropwise over 2 hours, and then heated and stirred at 85° C. for 2 hours. Seed polymerization was performed. After the polymerization was completed, the mixture was cooled to 28° C. to prepare an aqueous dispersion [S1] of the composite particles [s1] containing the hybrid crystalline polyester resin particles (c1).

  The volume-based median diameter of the composite particles [s1] in this aqueous dispersion [S1] was 270 nm.

[Preparation of Aqueous Dispersion of Composite Particles [S2] to [S8]]
The amount of the monomer added was changed so that the resin composition of the coating resin had the molar ratio shown in Table 3 below, and the type of seed (hybrid crystalline polyester resin particles) used was changed as shown in Table 3. Further, the above [preparation of aqueous dispersion of composite particles [S1]] except that the addition amount of the aqueous dispersion was changed so that the content ratio of the coating resin and the seed was as shown in Table 3 in terms of mass ratio. In the same manner as above, aqueous dispersions [S2] to [S8] of composite particles [s2] to [s8] were prepared.

  The volume-based median diameters of the composite particles [s2] to [s8] in the aqueous dispersions [S2] to [S8] were the same as those of the composite particles [s1].

  In addition, "-" in the following Table 3 shows that the monomer was not used.

[Preparation of aqueous dispersion [Bk] of colorant particles]
90 parts by mass of sodium polyoxyethylene-2-dodecyl ether sulfate was dissolved in 1510 parts by mass of ion-exchanged water with stirring, and while stirring this solution, carbon black "Regal (registered trademark) 330" as a colorant (manufactured by Cabot Corp.) ) Was gradually added, and then dispersed using CLEARMIX (registered trademark) (manufactured by M Technique Co., Ltd.) to prepare an aqueous dispersion liquid [Bk] of colorant particles. The volume-based median diameter of the colorant particles in the colorant particle dispersion [Bk] was 120 nm.

<Example 1>
[Preparation of Toner [1]]
In a zebra flask equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introducing device, 2500 parts by mass of ion-exchanged water, 600 parts by mass of an aqueous dispersion [A1] of amorphous resin particles [A1] (main resin) (solid) (In terms of minutes), 300 parts by weight of the aqueous dispersion [S1] of the composite particles [S1] (in terms of solid content), and 500 parts by weight of the aqueous dispersion [Bk] of the colorant particles were prepared, and the liquid temperature was adjusted to 25°C. Then, the pH was adjusted to 10 by adding a sodium hydroxide aqueous solution having a concentration of 25% by mass.

  Next, an aqueous solution prepared by dissolving 54.3 parts by mass of magnesium chloride hexahydrate in 54.3 parts by mass of ion-exchanged water was added, and then the temperature of the system was raised to 97° C. And the agglutination reaction of the colorant particles was started.

  After the start of this agglutination reaction, sampling is performed periodically, and the volume-based median diameter of the particles is measured using a particle size distribution measuring device “Coulter Multisizer 3” (manufactured by Beckman Coulter, Inc.), and the volume-based median is measured. Aggregation was performed while continuing stirring until the diameter became 6.3 μm.

  Then, an aqueous solution prepared by dissolving 23.0 parts by mass of sodium chloride in 92 parts by mass of ion-exchanged water was added, the system temperature was set to 95° C., and stirring was continued for 3 hours, and the flow-type particle image analyzer “FPIA-2100” was added. (When manufactured by Sysmex), when the average circularity reached 0.910, the solution was cooled to 30° C. under the condition of 6° C./min, and a sodium hydroxide aqueous solution having a concentration of 25% by mass was added to adjust the pH to 10. Adjusted to. Then, the temperature of the system was set to 95° C., stirring was continued for 1 hour, and when the average circularity reached 0.940, the reaction was stopped by cooling to 30° C. under the condition of 6° C./min. A dispersion of toner particles was obtained. The volume-based median diameter of the toner base particles after cooling was 6.1 μm, and the average circularity was 0.941.

  The thus-obtained dispersion of toner particles was subjected to solid-liquid separation using a basket-type centrifuge “MARK III Model No. 60×40” (manufactured by Matsumoto Kikai Co., Ltd.) to form a wet cake. This wet cake was repeatedly washed and solid-liquid separated by the basket-type centrifuge until the electric conductivity of the filtrate became 15 μS/cm, and then using a “flash jet dryer” (manufactured by Seishin Enterprise Co., Ltd.), Toner particles [1] were obtained by spraying an air stream having a temperature of 40° C. and a humidity of 20% RH until the water content became 0.5% by mass, and cooling to 24° C.

  To the obtained toner particles [1], 1% by mass of hydrophobic silica particles and 1.2% by mass of hydrophobic titanium oxide particles were added, and a peripheral speed of the rotor was set to 24 m/s using a Henschel mixer. The mixture was mixed for 20 minutes, and the external additive was added by passing through a 400-mesh sieve to obtain a toner [1] containing toner particles [1].

  When the softening point (Tsp) of the obtained toner [1] was measured, it was 100°C.

  In toner [1], the shape and particle size of the toner particles did not change from those of the toner base particles due to the addition of the hydrophobic silica particles and the hydrophobic titanium oxide particles.

<Examples 2 to 14, Comparative Examples 1 to 5>
[Preparation of Toners [2] to [19]]
The types of the aqueous dispersion liquid of the amorphous resin particles and the aqueous dispersion liquid of the composite particles were changed as shown in Table 4 below, and the content ratio of each resin was as shown in Table 4 in terms of mass ratio. Toners [2] to [19] were obtained in the same manner as in Example 1 except that the addition amount of the aqueous dispersion was changed.

  In Toner [8] of Example 8, the aqueous dispersion [C2] of the hybrid crystalline polyester resin particles [c2] was used in place of the aqueous dispersion [S1] of the composite particles [s1].

  In Toner [13] of Example 13, an aqueous dispersion [C2] of hybrid crystalline polyester resin particles [c2] was used in place of the aqueous dispersion [S1] of composite particles [c1].

  In Toner [14] of Example 14, an aqueous dispersion [C7] of crystalline polyester resin particles [c7] was used instead of the aqueous dispersion [S1] of composite particles [s1].

  In the toner [15] of Comparative Example 1, the aqueous dispersion [C2] of the hybrid crystalline polyester resin particles [c2] was used in place of the aqueous dispersion [A1] of the amorphous resin particles [a1], Instead of the aqueous dispersion liquid [S1] of the particles [s1], an aqueous dispersion liquid [C6] of the hybrid crystalline polyester resin particles [c6] was used.

  In the toner [16] of Comparative Example 2, no substitute for the aqueous dispersion [S1] of the composite particles [s1] was added.

  In the toner [17] of Comparative Example 3, the aqueous dispersion [C6] of the crystalline polyester resin particles [c6] was used in place of the aqueous dispersion [A11] of the resin particles [a11], and the composite particles [s1] It was prepared without adding a substitute for the aqueous dispersion [S1].

  The toner [18] of Comparative Example 4 was prepared by using the aqueous dispersion [C2] of the hybrid crystalline polyester resin particles [c2] instead of the aqueous dispersion [S1] of the composite particles [s1].

[Manufacturing of developer]
To each of the toners [1] to [19], a ferrite carrier coated with a silicone resin and having a volume-based median diameter of 60 μm was added so that the toner concentration was 6% by mass, and mixed by a V-type mixer. By doing so, developers [1] to [19] were manufactured.

[Production of cyan toner, cyan developer, magenta toner, magenta developer]
For the cyan toner and magenta toner used in the secondary color fixing property evaluation of Evaluation 2 described below, C.I. I. Pigment Blue 15:3 (copper phthalocyanine, colorant particles [cyan]), and C.I. I. Pigment Red 122 (dimethylquinacridone, colorant particles [magenta]), except that the above-mentioned [Preparation of aqueous dispersion of colorant particles] was used, an aqueous dispersion [cyan] of colorant particles [cyan] was prepared. ] And an aqueous dispersion of colorant particles [magenta] [magenta].

  Thereafter, except that 400 parts by mass of the aqueous dispersion liquid [Ck] of the colorant particles [cyan] was used instead of 500 parts by mass of the aqueous dispersion liquid [Bk] of the colorant particles [Bk], [Production of Toner] A cyan toner [1] was obtained in the same manner as in Example 1. Further, in place of 500 parts by mass of the aqueous dispersion liquid [Bk] of the colorant particles [Bk], 400 parts by mass of the aqueous dispersion liquid [Magenta] of the colorant particles [magenta] is used. [Preparation of]], and magenta toner [1] was obtained. For toners [2] to [19], cyan toners [2] to [19] and magenta toners [2] to [19] were obtained in the same manner as above.

  Thereafter, using the cyan toners [1] to [19] and the magenta toners [1] to [19] thus obtained, the cyan developers [1] to [19], Magenta developers [1] to [19] were manufactured.

[Performance evaluation]
<Evaluation 1: load variation type scratch test>
As an image forming apparatus, a commercially available copying machine “bizhub PRO (registered trademark) C6550” (manufactured by Konica Minolta Co., Ltd.) was developed and transferred directly from the developing sleeve onto the glass substrate, and developed so that a thick glass substrate could pass through. A modified one was used so that the distance from the sleeve to the side where development and transfer was performed could be changed, and the paper passage route was modified so that the glass substrate was not deformed. As a developer, the developer [1] to [19] is mounted, and a slide glass (manufactured by AS ONE Co., Ltd., model number 10117102, cutting type, not surface-treated), a solid image with a toner adhesion amount of 16 g/m ² was fixed. In a commercially available copying machine "biz PRO (registered trademark) C6550" as an image fixing device, the surface temperature of the fixing heating roller in the fixing unit of the heat roller fixing method is the minimum fixing temperature obtained in the low temperature fixing property evaluation of Evaluation 2 described later. Adjust the temperature to +25℃, modify the rotation speed of the heat roller so that the fixing time is 4 seconds, and modify so that the pressure of the heat roller is 200 kPa. A remodeled one was used. Using the image fixing device as described above, the developers [1] to [19] are mounted as developers, and the above surface treatment is not performed in an environment of normal temperature and normal humidity (temperature 20° C., humidity 50% RH). A solid image having a toner adhesion amount of 16 g/m ² was fixed on a slide glass.

  A load variation type scratch test was carried out using a load variation type friction wear tester shown below, using a sapphire terminal having a tip diameter of 50 μm. In the load-variable scratch test, the load increases as the scratch distance increases, and the starting load can be changed depending on the position where the glass substrate is installed. From the change in torque, the critical load (the load when the separation of the solid image starts) can be determined, and the critical load can also be determined by observing the peeling state of the scratched portion. In this evaluation, the critical load was measured by the change in torque.

  If the horizontal axis is the load and the vertical axis is the torque applied to the terminal, and the relationship is plotted in a graph, the gradient of the change in torque is less than 15 mN/g when the terminal passes over the toner image. When peeling starts, the gradient of change in torque becomes 15 mN/g or more. Therefore, when the load was increased, the load at which the slope became 15 mN/g or more for the first time was defined as the critical load.

Equipment: HEIDON Tribogear 18L Scratch Strength Tester (Shinto Kagaku Co., Ltd.)
Terminal: Sapphire needle Tip diameter 50μm
Load increase rate: 200g/min
Scratch speed: 200 mm/min.

  When the HEIDON Tribogear 18L scratch strength tester is used, the scratch test can be performed even if a load of 200 g or more is used by modifying the sample installation part.

<Evaluation 1: Evaluation of secondary color fixability (evaluation of image peeling at the folded portion)>
Using a modified machine of "bizhub PRO (registered trademark) C6500" described above, cyan developers [1] to [19] and magenta developers [1] to [19] were installed as developers, and the temperature was maintained at room temperature and normal humidity (temperature). Under an environment of 20° C. and humidity of 50% RH, a solid image of secondary colors of cyan and magenta was developed on an A4 size high-quality paper with a toner adhesion amount of 11 g/m ² . Then, the transferred paper was fixed in an environment of 10° C./10% RH by setting the temperature of the fixing heat roller to 160° C. The fixed solid image was folded by a folding machine, air of 0.35 MPa was blown on it, and the state of the fold was evaluated according to the following five grades with reference to a limit sample:
Rank 5: No peeling at all folds Rank 4: Peeling at some folds Rank 3: Fine linear peeling at folds Rank 2: Thick peeling at folds Rank 1: Large peeling at image.

  Ranks 5 to 3 are practically problem-free levels, and ranks 2 to 1 are practically problematic.

<Evaluation 2: Evaluation of low temperature fixability (minimum fixing temperature)>
In a commercially available copying machine “biz PRO (registered trademark) C754” (manufactured by Konica Minolta Co., Ltd.) as an image forming apparatus, the surface temperature of the fixing heating roller in the fixing unit of the heat roller fixing method is set in the range of 120 to 200° C. I used a modified version so that I could change it. Solid images with toner adhesion amount of 8 mg/cm ² on A4 size high-quality paper under the conditions of normal temperature and normal humidity (temperature 20° C., humidity 50% RH), by mounting developers [1] to [19] as developers. The fixing experiment for fixing was repeated up to 200° C. while changing the set fixing temperature from 135° C. in increments of 5° C. Among the fixing experiments in which the image stain due to the low temperature offset was not visually observed, the lowest temperature was evaluated as the lowest fixing temperature. Those having a minimum fixing temperature of 165° C. or lower were judged to be acceptable.

  The properties of each toner and the evaluation results are shown in Table 4 below. In addition, "-" in the column of contained resin in Table 4 below indicates that the resin was not used. The “total carboxy group concentration” represents the total of the carboxy group concentration of the main resin (matrix phase) and the carboxy group concentration of the coating resin.

  As can be seen from Table 4 above, the toners of all the examples are suppressed in image peeling at the folded portion and are excellent in low-temperature fixability.

  On the other hand, it is understood that the toners of Comparative Examples 1 to 4 have a critical load of less than 30 gf, and the images are often peeled off at the folded portion, which is not suitable for practical use. It can be seen that the toner of Comparative Example 5 has a low softening point and thus is inferior in low temperature fixability.

Claims (2)

A toner for developing an electrostatic latent image containing toner particles containing a binder resin,
The softening point of the toner is 115° C. or lower,
When a scratch test of the surface of the image formed by the toner formed on the glass substrate with an adhesion amount of 16 g/m ² was performed by a load variation type friction wear tester using a sapphire needle having a tip diameter of 50 μm, critical load of Ri der more than 30gf,
The binder resin has a domain matrix structure,
The matrix phase of the domain matrix structure includes a first amorphous resin,
The domain phase of the domain matrix structure, a crystalline polyester polymerized segment, and a core particle containing a hybrid crystalline polyester resin chemically bonded to other amorphous polymerized segment other than the polyester polymerized segment, the core particle A shell portion containing a second amorphous resin that covers the surface of, and a resin having a core-shell structure consisting of:
The ester group concentration of the hybrid crystalline polyester resin is 0.1 mmol/g or more and 12 mmol/g or less,
The first amorphous resin and the second amorphous resin each have a carboxy group and contain a structural unit derived from a (meth)acrylic acid ester monomer represented by the following chemical formula (1) and a diamine. Toner for developing an electrostatic latent image containing a constitutional unit derived from a functional (meth)acrylic acid ester monomer:
In the above chemical formula (1), R ₁ is a hydrogen atom or a methyl group, R ₂ is an alkyl group having a main chain of 5 or more carbon atoms, and in this case, R ₂ is an alkyl group bonded to the main chain. It may be a branched alkyl group. The electrostatic latent image developing according to claim 1 , wherein the sum of the carboxy group concentrations of the first amorphous resin and the second amorphous resin is 0.2 mmol/g or more and 1 mmol/g or less. toner.