JP7797983B2 - Method for producing toner binder and method for producing toner - Google Patents

Description

The present invention relates to a method for producing a toner binder and a method for producing a toner.

In recent years, along with the promotion of miniaturization, speedup, higher image quality and higher reliability of electrophotographic apparatuses, there has been a strong demand for improved low-temperature fixability of toners from the viewpoint of energy conservation, namely, reducing energy consumption in the fixing process.
The toner binder has a significant effect on the above-mentioned toner characteristics, and known examples include polystyrene resin, styrene-acrylic resin, polyester resin, epoxy resin, polyurethane resin, and polyamide resin. Recently, polyester resin has been attracting particular attention because it is easy to achieve a balance between storage stability and fixability.
For example, a toner has been proposed in which a crystalline polyester resin and an amorphous resin are kneaded at low temperatures with the aim of achieving low-temperature fixability (see Patent Document 1).
However, when the particle size of the toner is reduced to meet the demand for higher image reliability such as higher fixing strength, the dispersibility of the crystalline polyester resin in the toner using the above-mentioned crystalline polyester resin is not sufficient, and improvement is desired.

JP 2012-189871 A

The present invention aims to provide a method for producing a toner binder and toner containing a crystalline polyester (A) and an amorphous polyester (B), which has excellent dispersibility of the crystalline polyester in the amorphous polyester.

The present inventors have conducted extensive research and have arrived at the present invention.
That is, the present invention provides a method for producing a toner binder containing a crystalline polyester (A) and an amorphous polyester (B), wherein the crystalline polyester (A) is a crystalline polyester containing 60 to 100 mol % in total of an aliphatic diol having 2 to 24 carbon atoms and terephthalic acid based on the total number of moles of raw material monomers of (A), and the peak top temperature (Tm) of an endothermic peak of the crystalline polyester (A) measured by a differential scanning calorimeter (DSC) is 120 to 130°C. 0°C , and a step (1) of kneading the crystalline polyester (A) and the amorphous polyester (B) at a temperature equal to or lower than the peak top temperature (Tm) of the endothermic peak of the crystalline polyester (A) , wherein the difference (Tm - Tk) between the temperature (Tk) at which the crystalline polyester (A) and the amorphous polyester (B) are kneaded in the step (1) and the peak top temperature (Tm) of the endothermic peak of the crystalline polyester (A) is 10 to 50°C .

The toner binder and toner manufacturing method of the present invention is a method for manufacturing a toner binder and toner containing a crystalline polyester (A) and an amorphous polyester (B), and has the effect of being able to obtain a toner binder and toner in which the crystalline polyester has excellent dispersibility in the amorphous polyester.

1 shows TEM images (magnifications of 1000 and 3000) of the toner binders obtained in Examples 1 and 2 and Comparative Examples 1 and 2.

The present invention relates to a method for producing a toner binder containing a crystalline polyester (A) and an amorphous polyester (B), wherein the crystalline polyester (A) has an endothermic peak top temperature (Tm) of 100 to 150°C as measured by a differential scanning calorimeter (DSC), and the method includes step (1) of kneading the crystalline polyester (A) and the amorphous polyester (B) at a temperature equal to or lower than the endothermic peak top temperature (Tm) of the crystalline polyester (A).

In the present invention, the polyester resin is a polycondensate of a polyol and a polycarboxylic acid. The production method of the present invention is a method for producing a toner binder containing a crystalline polyester (A) and an amorphous polyester (B).
In the present invention, "crystalline" means that in differential scanning calorimetry (also referred to as DSC measurement), the DSC curve has a peak top temperature (Tm) of an endothermic peak.
The method for measuring the peak top temperature (Tm) of the endothermic peak will be described below.
Measurement is performed using a differential scanning calorimeter (e.g., DSC Q20 manufactured by TA Instruments, Inc.). The sample is first heated from 30°C to 180°C at 10°C/min, then cooled from 180°C to 0°C at 10°C/min, and then heated a second time from 0°C to 180°C at 10°C/min. The top temperature of the endothermic peak during the second heating process is taken as the peak top temperature (Tm) of the endothermic peak.

The crystalline polyester (A) in the present invention is a crystalline polyester resin obtained by polycondensation of a component containing an alcohol component and a carboxylic acid component. From the viewpoint of low-temperature fixability and heat-resistant storage stability, the crystalline polyester (A) is preferably a crystalline polyester obtained from two or more alcohol components and/or two or more carboxylic acid components.
The alcohol component includes a diol and a polyol having three or more valences, and the carboxylic acid component includes a dicarboxylic acid and a polycarboxylic acid having three or more valences.

Diols include linear aliphatic diols having 2 to 20 carbon atoms (ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,15-pentadecanediol, 1,18-octadecanediol, 1,19-nonadecanediol, and 1,20-eicosanediol), alicyclic diols having 6 to 36 carbon atoms (1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,1-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 5-norbornene-2,3- dimethanol, hydrogenated bisphenol A, spiroglycol, isosorbide, and alkylene oxide (hereinafter, "alkylene oxide" may be abbreviated as AO) adducts of the above alicyclic diols, and aromatic diols (1,3-benzenedimethanol, 1,4-benzenedimethanol, bisphenol A, bisphenol F, bisphenol B, bisphenol AD, bisphenol S, trichlorobisphenol A, tetrachlorobisphenol A, dibromobisphenol F, 2-methylbisphenol A, 2,6-dimethylbisphenol A, 2,2'-diethylbisphenol F, and alkylene oxide adducts of the above aromatic diols, etc.).

Examples of trihydric or higher polyols include polyhydric aliphatic alcohols (alkane polyols and their intramolecular or intermolecular dehydration products, such as glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, sorbitol, sorbitan, and polyglycerin; sugars and their esters, such as sucrose and methyl glucoside); AO adducts (2-30 moles added) of trisphenols (such as trisphenol PA); AO adducts (2-30 moles added) of novolak resins (such as phenol novolak and cresol novolak); and acrylic polyols (such as copolymers of hydroxyethyl (meth)acrylate and other vinyl monomers).

Of the above alcohol components, linear aliphatic diols having 2 to 20 carbon atoms are preferred from the viewpoint of low-temperature fixability and heat-resistant storage stability, and linear aliphatic diols having 2 to 12 carbon atoms are more preferred.

Dicarboxylic acids include linear aliphatic dicarboxylic acids having 2 to 50 carbon atoms (such as succinic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, and 1,18-octadecanedicarboxylic acid), alicyclic dicarboxylic acids having 8 to 36 carbon atoms (such as 1,4-cyclohexanedicarboxylic acid), and aromatic dicarboxylic acids having 8 to 36 carbon atoms (such as phthalic acid, isophthalic acid, and terephthalic acid).

Examples of trivalent or higher polycarboxylic acids include aromatic polycarboxylic acids having 9 to 20 carbon atoms (such as trimellitic acid and pyromellitic acid).

Of the above carboxylic acid components, from the viewpoints of low-temperature fixability and heat-resistant storage stability, linear aliphatic dicarboxylic acids having 2 to 50 carbon atoms and aromatic dicarboxylic acids having 8 to 36 carbon atoms are preferred, and linear aliphatic dicarboxylic acids having 2 to 10 carbon atoms and aromatic dicarboxylic acids having 8 to 10 carbon atoms are more preferred.

In the present invention, it is preferable that 50 mol% or more of all alcohol components used in the crystalline polyester (A) are aromatic dicarboxylic acids having 8 to 10 carbon atoms, more preferably 75 mol% or more, and even more preferably 95 mol% or more.

In the present invention, it is preferable that terephthalic acid account for 50 mol% or more of the total alcohol components used in the crystalline polyester (A), more preferably 75 mol% or more, and even more preferably 95 mol% or more.

The reaction ratio between the alcohol component and the carboxylic acid component, expressed as the molar ratio of hydroxyl groups to carboxyl groups {[OH]/[COOH]}, is preferably 1/2 to 2/1, more preferably 1/1.3 to 1.5/1, and even more preferably 1/1.2 to 1.4/1. The hydroxyl groups are derived from the alcohol component.

In the present invention, crystalline polyester (A) can be produced in the same manner as known polyester production methods. For example, it can be produced by reacting components containing an alcohol component and a carboxylic acid component in an inert gas (such as nitrogen gas) atmosphere at a reaction temperature of preferably 150 to 280°C, more preferably 160 to 250°C, and even more preferably 170 to 235°C. Furthermore, to ensure that the polycondensation reaction is carried out reliably, the reaction time is preferably 30 minutes or more, more preferably 2 to 40 hours. It is also effective to reduce the pressure to improve the reaction rate at the end of the reaction.

In this case, an esterification catalyst can be used if necessary.
Examples of the esterification catalyst include tin-containing catalysts (e.g., dibutyltin oxide), antimony trioxide, titanium-containing catalysts [e.g., titanium alkoxides, potassium oxalate titanate, titanium terephthalate, titanium terephthalate alkoxides, the catalysts described in JP-A-2006-243715 (titanium diisopropoxybistriethanolaminate, titanium dihydroxybistriethanolaminate, titanium monohydroxytristriethanolaminate, titanyl bistriethanolaminate, and intramolecular polycondensates thereof, and the catalysts described in JP-A-2007-11307 (titanium tributoxyterephthalate, titanium triisopropoxyterephthalate, titanium diisopropoxyditerephthalate, and the like)], zirconium-containing catalysts (e.g., zirconyl acetate), and zinc acetate.
Among the esterification catalysts, titanium-containing catalysts are preferred from the viewpoint of low-temperature fixability, and the catalysts described in JP-A No. 2006-243715 and JP-A No. 2007-11307 are more preferred.

The peak top temperature (Tm) of the endothermic peak of the crystalline polyester (A) in the present invention is 100 to 150°C, preferably 110 to 140°C, and more preferably 120 to 130°C.
If the melting point is 100° C. or higher, the image strength is good, and if it is 150° C. or lower, the low-temperature fixability is good.
For example, if the crystalline polyester (A) is a crystalline polyester containing 60 to 100 mol % in total of an aliphatic diol having 2 to 24 carbon atoms and terephthalic acid, based on the total number of moles of the raw material monomers of (A), the peak top temperature (Tm) of the endothermic peak can be easily achieved.

The viscosity of the crystalline polyester (A) in the present invention at 100°C is preferably 10 to 10,000 mPa·s, and more preferably 400 to 7,000 mPa·s. If the viscosity at 100°C is 10 mPa·s or higher, the heat-resistant storage stability will be good, and if it is 10,000 mPa·s or lower, the low-temperature fixability will be good.

The ester group concentration of the crystalline polyester (A) in the present invention is preferably 40 to 60% by weight, more preferably 45 to 55% by weight, based on the weight of (A). When the ester group concentration is within this range, compatibility with the amorphous polyester (B) is good, and low-temperature fixability is excellent.
The ester group concentration of the crystalline polyester (A) based on the weight of (A) can be calculated from the number of ester groups [—C(═O)O—] in (A) and is defined as the weight % of the ester groups present in 1 g of (A).
The actual ester group concentration can be calculated by determining the monomer composition constituting (A) and the number of ester groups using nuclear magnetic resonance spectroscopy (NMR) or the like, or by determining the number of ester groups from the ratio of the amounts of raw materials used in the production of (A).

The heat absorption amount of the crystalline polyester (A) is preferably 5 to 70 J/g, and more preferably 40 to 60 J/g. If the heat absorption amount is 5 J/g or more, low-temperature fixability will be good, and if it is 70 J/g or less, heat-resistant storage stability will be good.

The acid value of the crystalline polyester (A) is preferably 0 to 75 mgKOH/g, and more preferably 0 to 35 mgKOH/g.

The hydroxyl value of the crystalline polyester (A) is preferably 0 to 120 mgKOH/g, and more preferably 5 to 20 mgKOH/g.

The number average molecular weight (hereinafter sometimes abbreviated as Mn) of the crystalline polyester (A) is preferably 1,000 to 1,000,000, and more preferably 2,000 to 50,000.

The weight-average molecular weight (hereinafter sometimes abbreviated as Mw) of the crystalline polyester (A) is preferably 8,000 to 10,000,000, and more preferably 10,000 to 20,000. An Mw of 10,000 or more results in good fixing strength, while an Mw of 20,000 or less results in good low-temperature fixing properties.

The resin composition of the amorphous polyester (B) in the present invention is not particularly limited as long as it is an amorphous polyester that is a polycondensation product of an alcohol component (x) and a carboxylic acid component (y).
In the present invention, "amorphous" means that when the transition temperature of a sample is measured using a differential scanning calorimeter, there is no peak top temperature of the endothermic peak.

Examples of the alcohol component (x) of the amorphous polyester (B) include a diol (g) and a trihydric or higher polyol (h).
Examples of the carboxylic acid component (y) include dicarboxylic acids (i), trivalent or higher polycarboxylic acids (j), and acid anhydrides or lower alkyl esters thereof.

Examples of the diol (g) include alkylene glycols having 2 to 36 carbon atoms, alkylene ether glycols having 4 to 36 carbon atoms, alicyclic diols having 4 to 36 carbon atoms, alkylene oxide adducts of alkylene glycols or alicyclic diols, alkylene oxide adducts of bisphenols, polylactone diols, and polybutadiene diols.
Specific examples of alkylene glycols having 2 to 36 carbon atoms include ethylene glycol, 1,2-propanediol (propylene glycol), 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, octanediol, decanediol, dodecanediol, tetradecanediol, neopentyl glycol, and 2,2-diethyl-1,3-propanediol.
Specific examples of alkylene ether glycols having 4 to 36 carbon atoms include diethylene glycol, triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, and polytetramethylene ether glycol.
Specific examples of the alicyclic diol having 4 to 36 carbon atoms include 1,4-cyclohexanedimethanol and hydrogenated bisphenol A.
In the alkylene oxide adduct of an alkylene glycol or an alicyclic diol, examples of the alkylene glycol or alicyclic diol include those described above, and examples of the alkylene oxide include an ethylene oxide (hereinafter abbreviated as EO) adduct, a propylene oxide (hereinafter abbreviated as PO) adduct, and a butylene oxide (hereinafter abbreviated as BO) adduct.
Examples of alkylene oxide adducts of bisphenol include AO (EO, PO, BO, etc.) adducts (number of moles added: 2 to 30) of bisphenol A, bisphenol F, bisphenol S, etc.
Examples of polylactone diols include poly-ε-caprolactone diol.

Examples of the tri- or higher hydric polyol (h) include tri- or higher hydric polyaliphatic alcohols having 3 to 36 carbon atoms, AO adducts of polyaliphatic alcohols (number of added moles: 2 to 120), AO adducts of trisphenols (such as trisphenol PA) (number of added moles: 2 to 30), AO adducts of novolak resins (such as phenol novolak and cresol novolak) (number of added moles: 2 to 30), and acrylic polyols [such as copolymers of hydroxyethyl (meth)acrylate and other vinyl monomers].
Examples of polyhydric aliphatic alcohols having 3 to 36 carbon atoms and having a valence of 3 or more include alkane polyols and their intramolecular or intermolecular dehydration products, as well as sugars (such as sucrose) and compounds in which part of the alcohol in a sugar is alkyl etherified.
Specific examples of alkane polyols and their intramolecular or intermolecular dehydration products include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, sorbitol, sorbitan, and polyglycerin.

Among the above alcohol components (x), from the viewpoints of low-temperature fixability and heat-resistant storage stability, alkylene glycols having 2 to 36 carbon atoms and alkylene oxide adducts of bisphenols are preferred, and AO adducts of bisphenol A are more preferred.

Examples of the dicarboxylic acid (i) include alkanedicarboxylic acids having 4 to 36 carbon atoms, alkenylsuccinic acids, alicyclic dicarboxylic acids having 6 to 40 carbon atoms, alkenedicarboxylic acids having 4 to 36 carbon atoms, and aromatic dicarboxylic acids having 8 to 36 carbon atoms.
Examples of the alkanedicarboxylic acid having 4 to 36 carbon atoms include succinic acid, adipic acid, sebacic acid, azelaic acid, dodecanedicarboxylic acid, octadecanedicarboxylic acid, and decylsuccinic acid.
Examples of alkenyl succinic acids include dodecenyl succinic acid, pentadecenyl succinic acid, and octadecenyl succinic acid.
Examples of the alicyclic dicarboxylic acid having 6 to 40 carbon atoms include dimer acid (dimerized linoleic acid).
Examples of the alkene dicarboxylic acid having 4 to 36 carbon atoms include maleic acid, fumaric acid, and citraconic acid.
Examples of aromatic dicarboxylic acids having 8 to 36 carbon atoms include phthalic acid, isophthalic acid, terephthalic acid, and naphthalenedicarboxylic acid.

Examples of trivalent or higher polycarboxylic acids (j) include aromatic polycarboxylic acids having 9 to 20 carbon atoms (such as trimellitic acid and pyromellitic acid) and aliphatic (including alicyclic) tricarboxylic acids having 6 to 36 carbon atoms (such as hexanetricarboxylic acid and decanetricarboxylic acid).

As the dicarboxylic acid (i) or trivalent or higher polycarboxylic acid (j), the acid anhydrides or lower alkyl esters having 1 to 4 carbon atoms (methyl ester, ethyl ester, isopropyl ester, etc.) of the above may also be used.

Among the carboxylic acid components (y), from the viewpoints of low-temperature fixability and heat-resistant storage stability, alkanedicarboxylic acids having 4 to 36 carbon atoms, aromatic dicarboxylic acids having 8 to 36 carbon atoms, and aromatic polycarboxylic acids having 9 to 20 carbon atoms are preferred, and alkanedicarboxylic acids having 4 to 20 carbon atoms, aromatic dicarboxylic acids having 8 to 20 carbon atoms, and trimellitic acid are more preferred.

The reaction ratio of the alcohol component (x) to the carboxylic acid component (y), expressed as the molar ratio of hydroxyl groups to carboxyl groups {[OH]/[COOH]}, is preferably 1/2 to 2/1, more preferably 1/1.3 to 1.5/1, and even more preferably 1/1.2 to 1.4/1. The hydroxyl groups are derived from the alcohol component.

In the present invention, the amorphous polyester (B) can be produced in the same manner as the crystalline polyester (A) described above, using a known polyester production method.

The glass transition temperature (hereinafter abbreviated as Tg) of the amorphous polyester (B) is preferably 20 to 90°C, and more preferably 40 to 80°C. A temperature of 20°C or higher provides excellent heat-resistant storage stability, while a temperature of 90°C or lower minimizes the inhibition of low-temperature fixability.

The acid value of the amorphous polyester (B) is preferably 0 to 75 mgKOH/g, and more preferably 7 to 24 mgKOH/g.

The hydroxyl value of the amorphous polyester (B) is preferably 0 to 120 mgKOH/g, and more preferably 1 to 70 mgKOH/g.

The number average molecular weight (hereinafter sometimes abbreviated as Mn) of the amorphous polyester (B) is preferably 1,000 to 1,000,000, and more preferably 2,000 to 8,000.

The weight-average molecular weight (hereinafter sometimes abbreviated as Mw) of the amorphous polyester (B) is preferably 2,000 to 200,000, and more preferably 4,000 to 150,000.

The 1/2 drop temperature of the amorphous polyester (B) is preferably 80 to 170°C, more preferably 95 to 150°C.
Two or more types of amorphous polyester (B) having different 1/2 temperature drop temperatures may be used in combination. A combination of one having a 1/2 temperature drop of 80°C or more and less than 115°C and one having a 1/2 temperature drop of 115°C or more and 170°C or less is preferred, and a combination of one having a 1/2 temperature drop of 85°C or more and 115°C or less and one having a 1/2 temperature drop of 120°C or more and 160°C or less is more preferred.

In the present invention, the weight ratio of the amorphous polyester (B) having a half-temperature drop temperature of 80°C or higher but lower than 115°C to the amorphous polyester (B) having a half-temperature drop temperature of 115°C or higher but lower than 170°C is preferably 50:50 to 80:20.

In the toner binder manufacturing method of the present invention, other binder resins can be contained in addition to the crystalline polyester (A) and the amorphous polyester (B). Examples of other resins include polyurethane resins, styrene resins, and epoxy resins. From the viewpoint of heat-resistant storage stability, polyurethane resins are preferred.

Examples of polyurethane resins include polyaddition products of diol (g) and polyisocyanate, and polyaddition products of the above-mentioned amorphous polyester and polyisocyanate.

Examples of polyisocyanates include aromatic polyisocyanates having 6 to 20 carbon atoms (excluding carbon atoms in NCO groups, the same applies below), aliphatic polyisocyanates having 2 to 18 carbon atoms, alicyclic polyisocyanates having 4 to 15 carbon atoms, araliphatic polyisocyanates having 8 to 15 carbon atoms, modified products of these polyisocyanates (such as modified products containing urethane groups, carbodiimide groups, allophanate groups, urea groups, biuret groups, uretdione groups, uretoimine groups, isocyanurate groups, and oxazolidone groups), and mixtures of two or more of these.

Specific examples of aromatic polyisocyanates having 6 to 20 carbon atoms include 1,3- or 1,4-phenylene diisocyanate, 2,4- or 2,6-tolylene diisocyanate (TDI), crude TDI, 2,4'- or 4,4'-diphenylmethane diisocyanate (MDI), crude MDI, 1,5-naphthylene diisocyanate, 4,4',4"-triphenylmethane triisocyanate, and m- or p-isocyanatophenylsulfonyl isocyanate.

Specific examples of aliphatic polyisocyanates having 2 to 18 carbon atoms include ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), dodecamethylene diisocyanate, 1,6,11-undecane triisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2,6-diisocyanatomethyl caproate, bis(2-isocyanatoethyl) fumarate, bis(2-isocyanatoethyl) carbonate, and 2-isocyanatoethyl-2,6-diisocyanatohexanoate.

Specific examples of alicyclic polyisocyanates having 4 to 15 carbon atoms include isophorone diisocyanate (IPDI), dicyclohexylmethane-4,4'-diisocyanate (hydrogenated MDI), cyclohexylene diisocyanate, methylcyclohexylene diisocyanate (hydrogenated TDI), bis(2-isocyanatoethyl)-4-cyclohexene-1,2-dicarboxylate, and 2,5- and/or 2,6-norbornane diisocyanate.

Specific examples of aromatic aliphatic polyisocyanates having 8 to 15 carbon atoms include m- and/or p-xylylene diisocyanate (XDI) and α,α,α',α'-tetramethylxylylene diisocyanate (TMXDI).
Furthermore, examples of the modified polyisocyanate include modified products containing a urethane group, a carbodiimide group, an allophanate group, a urea group, a biuret group, a uretdione group, a uretoimine group, an isocyanurate group, and an oxazolidone group.
Specific examples include modified MDI (urethane-modified MDI, carbodiimide-modified MDI, trihydrocarbyl phosphate-modified MDI, etc.), modified polyisocyanates such as urethane-modified TDI, and mixtures of two or more of these [for example, a combination of modified MDI and urethane-modified TDI (isocyanate-containing prepolymer)].

Of these polyisocyanates, preferred are aromatic polyisocyanates having 6 to 20 carbon atoms, aliphatic polyisocyanates having 2 to 18 carbon atoms, and alicyclic polyisocyanates having 4 to 15 carbon atoms, with aromatic polyisocyanates having 6 to 15 carbon atoms, aliphatic polyisocyanates having 4 to 12 carbon atoms, and alicyclic polyisocyanates having 6 to 15 carbon atoms being more preferred, and TDI, MDI, HDI, hydrogenated MDI, and IPDI being particularly preferred.

The method for producing a toner binder of the present invention is a method for producing a toner binder containing the crystalline polyester (A) and the amorphous polyester (B), and includes a step (1) of kneading the crystalline polyester (A) and the amorphous polyester (B) at a temperature equal to or lower than the peak top temperature (Tm) of the endothermic peak of the crystalline polyester (A).
By kneading the crystalline polyester (A) having a high endothermic peak top temperature (Tm) of 100 to 150°C with the amorphous polyester (B) at a temperature equal to or lower than the endothermic peak top temperature (Tm), a toner binder having excellent dispersibility of the crystalline polyester in the amorphous polyester can be obtained.
Crystalline polyester (A) having a high endothermic peak top temperature (Tm) of 100 to 150°C will crystallize after passing through a molten state when kneaded at a temperature higher than the endothermic peak top temperature (Tm). It is presumed that, due to the high melting point, crystal growth after kneading is rapid, resulting in large crystals and poor dispersibility. On the other hand, when kneaded at a temperature lower than the endothermic peak top temperature (Tm), the crystalline polyester (A) does not melt and is finely dispersed as crystals due to shear during kneading, resulting in better dispersibility.

From the viewpoint of dispersibility of the crystalline polyester, the difference (Tm - Tk) between the temperature (Tk) at which the crystalline polyester (A) and the amorphous polyester (B) are kneaded in step (1) and the peak top temperature (Tm) of the endothermic peak of the crystalline polyester (A) is preferably 10 to 50°C, and more preferably 20 to 30°C.

The time (resin residence time) for kneading the crystalline polyester (A) and the amorphous polyester (B) in step (1) is preferably 30 to 300 seconds, more preferably 30 to 60 seconds, from the viewpoint of dispersibility of the crystalline polyester.

In step (1), the kneading equipment can be any common equipment capable of kneading resins while controlling the temperature, such as a twin-screw kneader.

In the toner binder manufacturing method of the present invention, the weight ratio (A/B) of the crystalline polyester (A) to the amorphous polyester (B) is preferably 5/95 to 20/80 from the viewpoint of image strength.

The toner binder obtained by the production method of the present invention may be used to obtain resin particles for toner.
The content of the toner binder in the resin particles is preferably 30 to 97% by weight, more preferably 42 to 96% by weight, and even more preferably 50 to 95% by weight, based on the weight of the resin particles.

If necessary, the resin particles can be mixed with various known additives such as colorants, release agents, charge control agents, and fluidizing agents.

The colorant preferably contains one or more selected from the group consisting of black colorants, blue colorants, red colorants, and yellow colorants. As the colorant, any of dyes, pigments, etc. that are used as colorants for toners can be used.
Specific examples include carbon black, iron black, Sudan Black SM, Fast Yellow G, Benzidine Yellow, Solvent Yellow (21, 77, 114, etc.), Pigment Yellow (12, 14, 17, 83, etc.), India First Orange, Irgasin Red, Paranitoaniline Red, Toluidine Red, Solvent Red (17, 49, 128, 5, 13, 22, 48.2, etc.), Disperse Red, Carmine FB, Pigment Orange R, Lake Red 2G, Rhodamine FB, Rhodamine B Lake, Methyl Violet B Lake, Phthalocyanine Blue, Solvent Blue (25, 94, 60, 15.3, etc.), Pigment Blue, Brilliant Green, Phthalocyanine Green, Oil Yellow GG, Kayaset YG, Orazol Brown B, and Oil Pink OP. If necessary, magnetic powder (powder of ferromagnetic metals such as iron, cobalt and nickel, and compounds such as magnetite, hematite and ferrite) may be contained to also function as a colorant.
The content of the colorant is preferably 1 to 40 parts by weight, more preferably 2 to 15 parts by weight, based on 100 parts by weight of the total of the toner binder resin of the present invention. When a magnetic powder is used, the content of the magnetic powder is preferably 20 to 150 parts by weight, more preferably 30 to 120 parts by weight, based on 100 parts by weight of the total of the toner binder resin.

Releasing agents include natural waxes (such as beeswax, carnauba wax, and montan wax), petroleum waxes (such as paraffin wax, microcrystalline wax, and petrolatum), synthetic waxes (such as Fischer-Tropsch wax, polyethylene wax, polypropylene wax, oxidized polyethylene wax, and oxidized polypropylene wax), and synthetic ester waxes (such as fatty acid esters synthesized from fatty acids having 10 to 30 carbon atoms and alcohols having 10 to 30 carbon atoms). It is preferable to use one or more types selected from the group consisting of these releasing agents. The content of the releasing agent is preferably 0 to 30% by weight, more preferably 0.5 to 20% by weight, and even more preferably 1 to 10% by weight, based on 100 parts by weight of the total of the toner binder resin of the present invention.

When using the above-mentioned release agent, a modified wax may be used in combination, if necessary. The modified wax is a release agent to which a vinyl polymer chain has been grafted. Examples of release agents used in the modified wax include those similar to those used for the above-mentioned release agents, and the preferred examples are also similar. Examples of vinyl monomers that make up the vinyl polymer chain of the modified wax include styrene and methacrylic acid esters. The vinyl polymer chain may be a homopolymer or copolymer of a vinyl monomer. The content of the modified wax is preferably 0 to 15% by weight, more preferably 0.5 to 10% by weight, and even more preferably 1 to 5% by weight, based on 100 parts by weight of the total of the toner binder resin of the present invention.

The charge control agent may be either a positively chargeable charge control agent or a negatively chargeable charge control agent, and examples thereof include nigrosine dyes, triphenylmethane dyes containing a tertiary amine as a side chain, quaternary ammonium salts, polyamine resins, imidazole derivatives, quaternary ammonium base-containing polymers, metal-containing azo dyes, copper phthalocyanine dyes, salicylic acid metal salts, boron complexes of benzilic acid, sulfonic acid group-containing polymers, fluorine-containing polymers, halogen-substituted aromatic ring-containing polymers, etc. The content of the charge control agent may be 0 to 20% by weight, preferably 0.1 to 10% by weight, and more preferably 0.5 to 7.5% by weight, based on 100 parts by weight of the total of the binder resin for the toner of the present invention.

Fluidizing agents include silica, titania, alumina, fatty acid metal salts, silicone resin particles, and fluororesin particles, and two or more of these may be used in combination. Silica is preferred from the perspective of toner chargeability. Furthermore, hydrophobic silica is preferred from the perspective of toner transferability. The content of the fluidizing agent may be 0 to 10% by weight, preferably 0 to 5% by weight, and more preferably 0.1 to 4% by weight, based on 100 parts by weight of the total of the toner binder resin of the present invention.

The total weight of additives such as colorants, release agents, charge control agents, and fluidizing agents may be 3 to 70% by weight, preferably 4 to 58% by weight, and more preferably 5 to 50% by weight, based on the weight of the resin particles.

The volume average particle size (D50) of the resin particles is preferably 1 to 15 μm, more preferably 2 to 10 μm, and particularly preferably 3 to 7 μm. Keeping it within this range ensures good low-temperature fixability.

The method for producing the resin particles is not particularly limited, and may be a known kneading and pulverization method, a suspension polymerization method described in JP-B Nos. 36-10231, 59-53856, and 59-61842, an emulsion polymerization method typified by a soap-free polymerization method in which a toner is produced by directly polymerizing a monomer in the presence of a water-soluble polymerization initiator that is soluble in the monomer, an interfacial polymerization method such as a microcapsule production method, an in situ polymerization method, a coacervation method, an emulsion aggregation method in which at least one type of fine particles are aggregated to obtain particles of a desired particle size as disclosed in JP-A Nos. 62-106473 and 63-186253, a dispersion polymerization method characterized by monodispersity, a dissolution suspension method in which necessary resins are dissolved in a water-insoluble organic solvent and then converted into resin particles in water, or an ester elongation polymerization method, or a method in which resin particles are dispersed in carbon dioxide in a supercritical state.
Among the above manufacturing methods, the emulsion aggregation method in which at least one type of fine particles is aggregated to obtain particles of the desired particle size is preferred from the viewpoint of particle size control and storage stability of resin particles.

When resin particles are used as a toner, they are mixed with carrier particles such as iron powder, glass beads, nickel powder, ferrite, magnetite, and ferrite coated with a resin (acrylic resin, silicone resin, etc.) as needed, and used as a developer for an electric latent image. When carrier particles are used, the weight ratio of toner to carrier particles is preferably 1/99 to 99/1. Alternatively, an electric latent image can be formed by friction with a member such as a charging blade instead of carrier particles.
The toner does not necessarily contain carrier particles.

The toner production method of the present invention is a method for producing a toner containing a crystalline polyester (A) and an amorphous polyester (B), the method comprising: kneading the crystalline polyester (A) with the amorphous polyester (B) at a temperature equal to or lower than the endothermic peak top temperature (Tm) of the crystalline polyester (A), wherein the crystalline polyester (A) has an endothermic peak top temperature (Tm) of 100 to 150°C as measured by a differential scanning calorimeter (DSC). The other steps in the method, other than the step (1) of kneading the crystalline polyester (A) with the amorphous polyester (B) at a temperature equal to or lower than the endothermic peak top temperature (Tm), can be carried out using known methods.
In the present invention, a crystalline polyester (A) having a high endothermic peak top temperature (Tm) of 100 to 150°C and an amorphous polyester (B) are kneaded at a temperature equal to or lower than the endothermic peak top temperature (Tm), thereby making it possible to obtain a toner in which the crystalline polyester has excellent dispersibility in the amorphous polyester.

The toner production method of the present invention may include a step (1) of kneading the crystalline polyester (A) and the amorphous polyester (B) at a temperature equal to or lower than the peak top temperature (Tm) of the endothermic peak of the crystalline polyester (A). For example, the method includes the following production methods (i) to (ii):
(i) A method of producing a toner by carrying out the above-mentioned method for producing a toner binder, and then mixing various additives such as a colorant, a release agent, a charge control agent, a fluidizing agent, etc. by a known method (preferably at a temperature equal to or lower than the peak top temperature (Tm) of the endothermic peak of (A)).
(ii) A method for producing a toner by kneading a crystalline polyester (A), the amorphous polyester (B), and various additives (colorants, release agents, charge control agents, fluidizing agents, etc.) at a temperature equal to or lower than the peak top temperature (Tm) of the endothermic peak of the crystalline polyester (A).

The toner is fixed to a substrate (paper, polyester film, etc.) using a copier, printer, etc. to form a recording material. Methods for fixing to the substrate include well-known heat roll fixing and flash fixing methods.

Toner is used to develop electrostatic images or magnetic latent images in electrophotography, electrostatic recording, electrostatic printing, etc. More specifically, it is used to develop electrostatic images or magnetic latent images that are particularly suitable for full color applications.

The present invention will be further explained below with reference to examples and comparative examples, but the present invention is not limited to these. Unless otherwise specified, "parts" below refer to parts by weight.

The physical properties of crystalline polyester, amorphous polyester, toner, etc. were measured using the following methods.

<Peak Top Temperature (Tm) of Endothermic Peak of Crystalline Polyester>
Measurement was performed using a differential scanning calorimeter (e.g., "DSCQ20" manufactured by TA Instruments, Inc.). The crystalline polyester was first heated from 30°C to 180°C at a rate of 10°C/min, then cooled from 180°C to 0°C at a rate of 10°C/min, and then heated a second time from 0°C to 180°C at a rate of 10°C/min. The temperature showing the top of the endothermic peak during the second heating process was recorded as the peak top temperature (Tm) of the endothermic peak of the crystalline polyester.

<Amount of heat absorbed at the endothermic peak of crystalline polyester>
In the DSC curve during the second heating process observed under the same measurement conditions as in the measurement of the peak top temperature of the endothermic peak, a straight line was drawn connecting the point closest to the peak on the baseline below the endothermic onset temperature ( _T0 ) of the endothermic peak and the point closest to the peak on the baseline above the endothermic peak end point temperature, thereby calculating the endothermic amount at the endothermic peak having the peak top temperature of the endothermic peak.

<Number average molecular weight (Mn) and weight average molecular weight (Mw)>
The number average molecular weight (Mn) and weight average molecular weight (Mw) were measured under the following conditions using a sample solution obtained by dissolving a polyester resin in tetrahydrofuran (THF) and filtering off the insoluble matter with a glass filter.
Equipment: Tosoh Corporation HLC-8120
Column: 2 TSK GEL GMH6 columns (manufactured by Tosoh Corporation)
Measurement temperature: 40℃
Sample solution: 0.25 wt% THF solution Solution injection amount: 100 μl
Detector: Refractive index detector Reference material: 12 standard polystyrenes (TSKstandard POLYSTYRENE) manufactured by Tosoh Corporation (molecular weight: 500, 1,050, 2,800, 5,970, 9,100, 18,100, 37,900, 96,400, 190,000, 355,000, 1,090,000, 2,890,000)

<Acid value and hydroxyl value>
The measurement was carried out according to the method specified in JIS K 0070. However, the solvent for measuring the acid value was a mixed solvent of acetone, methanol, and toluene (acetone:methanol:toluene=12.5:12.5:75), and the solvent for measuring the hydroxyl value was THF.

<1/2 temperature drop>
Using a constant test force extrusion capillary rheometer flow tester (Shimadzu Corporation, CFT-500D), 1 g of a measurement sample was heated at a temperature increase rate of 6°C/min while applying a load of 1.96 MPa with the plunger, and the sample was extruded from a nozzle having a diameter of 1 mm and a length of 1 mm. A graph of "plunger depression amount (flow value)" versus "temperature" was plotted, and the temperature corresponding to half of the maximum plunger depression amount was read from the graph. This value (the temperature at which half of the measurement sample had flowed out) was defined as the half-depression temperature.

<Method for measuring glass transition temperature (Tg)>
Measurement was carried out using a differential scanning calorimeter (DSC Q20, manufactured by TA Instruments) according to the method (DSC method) specified in ASTM D3418-82 under the following conditions.
(1) Heating from 30°C to 150°C at 20°C/min. (2) Holding at 150°C for 10 minutes. (3) Cooling to -35°C at 20°C/min. (4) Holding at -35°C for 10 minutes. (5) Heating to 150°C at 20°C/min. (6) The differential scanning calorimetry curve measured during the process of (5) was analyzed to determine the glass transition temperature.

<Volume average particle diameter (D50) (μm), number average particle diameter (μm), particle size distribution (volume average particle diameter/number average particle diameter) of toner>
Measurement was carried out using a Coulter counter [trade name: Multisizer III (manufactured by Beckman Coulter, Inc.)].
First, 0.1 to 5 mL of a surfactant (alkylbenzene sulfonate) was added as a dispersant to 100 to 150 mL of an aqueous electrolyte solution, ISOTON-II (manufactured by Beckman Coulter). 2 to 20 mg of a measurement sample was then added, and the electrolyte solution in which the sample was suspended was subjected to a dispersion treatment using an ultrasonic disperser for approximately 1 to 3 minutes. The toner volume and number were measured using a 50 μm aperture with the measuring device, and the volume distribution and number distribution were calculated. From the obtained distribution, the toner's volume average particle diameter (D50) (μm), number average particle diameter (μm), and particle size distribution (volume average particle diameter/number average particle diameter) were determined.

<Production Example 1> [Synthesis of Crystalline Polyester (A-1)]
In a reaction vessel equipped with a cooling tube, a heating/cooling device, a thermometer, a stirrer, and a nitrogen inlet tube, 591 parts (50.0 mol%) of 1,10-decanediol, 520 parts (50.0 mol%) of terephthalic acid, and 1.5 parts of titanium dihydroxybis(triethanolamine) as a condensation catalyst were placed, and the resulting water was distilled off under a nitrogen stream at 170 ° C. for 8 hours. The temperature was then gradually increased to 220 ° C., and the resulting water was distilled off under a nitrogen stream for 4 hours. The reaction was then further carried out under a reduced pressure of 0.5 to 2.5 kPa, and the resin was taken out when the acid value reached 0.3 mg KOH / g. The taken-out resin was cooled to room temperature and then pulverized to obtain crystalline polyester (A-1). The crystalline polyester (A-1) had a number average molecular weight (Mn) of 4,000, a weight average molecular weight (Mw) of 11,000, a peak top temperature (Tm) of the endothermic peak of 128°C, an endothermic amount at the endothermic peak of 40 J/g, an acid value of 0.3 mgKOH/g, and a hydroxyl value of 8.2 mgKOH/g.

<Production Example 2> [Synthesis of Crystalline Polyester (A-2)]
Crystalline polyester (A-2) was obtained in the same manner as in Production Example 1, except that the raw materials shown in Table 1 were used. The number average molecular weight (Mn), weight average molecular weight (Mw), peak top temperature (Tm) of the endothermic peak, endothermic amount at the endothermic peak, acid value, and hydroxyl value of the obtained crystalline polyester are shown in Table 1.

The composition and resin properties of the crystalline polyester (A) obtained in Production Examples 1 and 2 are shown in Table 1.

<Production Example 3> [Synthesis of amorphous polyester (B-1)]
Into a reaction vessel equipped with a condenser, a stirrer, and a nitrogen inlet tube, 193 parts (14.6 mol%) of bisphenol A·PO 2-mol adduct (manufactured by Sanyo Chemical Industries, Ltd., "Hymer BP-2P"), 539 parts (35.4 mol%) of bisphenol A·PO 3-mol adduct (manufactured by Sanyo Chemical Industries, Ltd., "Hymer BP-3P"), 173 parts (26.7 mol%) of terephthalic acid, 67 parts (11.8 mol%) of adipic acid, 86 parts (11.5 mol%) of trimellitic anhydride, and 3.6 parts of titanium dihydroxybis(triethanolaminate) as a condensation catalyst were placed and reacted at 220°C for 20 hours while distilling off the generated water. The reaction was further carried out under a reduced pressure of 0.5 to 2.5 kPa, and when the temperature had dropped by half to 150°C, the mixture was removed using a steel belt cooler. The extracted resin was pulverized into particles to obtain amorphous polyester (B-1). The amorphous polyester (B-1) had a half drop temperature of 150°C, a glass transition temperature Tg of 60°C, an acid value of 23 mgKOH/g, a hydroxyl value of 1 mgKOH/g, and a weight average molecular weight Mw of 130,000.

<Production Example 4> [Synthesis of amorphous polyester (B-2)]
In another reaction vessel equipped with a cooling tube, a stirrer, and a nitrogen inlet tube, 324 parts (20.0 mol%) of bisphenol A-PO 2-mol adduct (Sanyo Chemical Industries, Ltd., "Hymer BP-2P"), 443 parts (30.0 mol%) of bisphenol A-EO 2-mol adduct (Sanyo Chemical Industries, Ltd., "Hymer BPE-20"), 280 parts (47.7 mol%) of terephthalic acid, 3.0 parts of titanium dihydroxybis (triethanol aminate) as a condensation catalyst, was added, and the temperature was raised to 230 ° C. under a reduced pressure of 0.5 to 2.5 kPa, while the produced water was distilled off, and the reaction was continued until the acid value was less than 2 mg KOH / g. It was then cooled to 180 ° C., and 14 parts (2.3 mol%) of trimellitic anhydride was added, and the mixture was reacted under normal pressure for 1 hour and then removed. The extracted resin was cooled to room temperature and then pulverized into particles to obtain amorphous polyester (B-2). The amorphous polyester (B-2) had a half drop temperature of 97°C, a glass transition temperature (Tg) of 58°C, an acid value of 8 mgKOH/g, a hydroxyl value of 55 mgKOH/g, and a weight average molecular weight (Mw) of 5,000.

<Examples 1 and 2 and Comparative Examples 1 and 2>
<Evaluation of Dispersibility of Crystalline Polyester (A) in Amorphous Polyester (B)>
(1) Production of Toner Binders 10 parts of each of the crystalline polyesters (A-1) to (A-2) were premixed with 27 parts of the amorphous polyester (B-1) and 63 parts of the amorphous polyester (B-2) using a Henschel mixer [FM10B, manufactured by Mitsui Miike Chemical Engineering Co., Ltd.], and then kneaded in a twin-screw kneader [IMC-9B20, manufactured by Imoto Machinery Co., Ltd.] at the temperature and for the residence time shown in Table 2 to obtain toner binders.
(2) Preparation and Evaluation of Evaluation Samples The resulting toner binder was embedded in a visible light-curable embedding resin (D-800, manufactured by Nissin EM Co., Ltd.), cut into 60 nm thick pieces using an ultrasonic ultramicrotome (EM5, manufactured by Leica), and then stained with ruthenium using a vacuum staining device (manufactured by Filgen). The dispersion state of the crystalline polyester in the amorphous polyester was then observed from a cross section of the resulting mixture using a transmission electron microscope (H7500, manufactured by Hitachi High-Technologies Corporation) at an accelerating voltage of 120 kV (Figures 1 to 8). The longest diameter of the crystalline polyester in the entire observed image was taken as the maximum particle size. Additionally, randomly selected enlarged images (x1000) were subjected to image processing using the free software "Image J" according to the following procedure, and the calculated "mean ferret" was taken as the average particle size of the crystalline polyester.
1. image type → 8bit
2. line → analyze → set scale
→ known distance 5.0
3. process → binary → median filter 10
4. image → adjust → threshold
5. process → binary → fill hole
6. analyze particle
(set mesearements → feret diameter)

<Evaluation of Low-Temperature Fixability, Charging Property, Heat-Resistant Storage Stability, and Fixing Strength of Toner>
(3) Production of Toner 10 parts of each of the crystalline polyesters (A-1) to (A-2), 27 parts of the amorphous polyester (B-1), and 63 parts of the amorphous polyester (B-2) were each added with 8 parts of a pigment carbon black "MA-100" [manufactured by Mitsubishi Chemical Corporation] as a colorant, 4 parts of a paraffin wax "HNP-9" [manufactured by Nippon Seiro Co., Ltd.] as a mold release agent, and 1 part by weight of a charge control agent "T-77" [manufactured by Hodogaya Chemical Co., Ltd.], and the mixture was premixed using a Henschel mixer [manufactured by Mitsui Miike Chemical Engineering Co., Ltd., FM10B], and then kneaded in a twin-screw kneader [manufactured by Imoto Machinery Co., Ltd., IMC-9B20] at the temperature and for the residence time shown in Table 2.
The resin particles were then finely pulverized using a supersonic jet mill, Labojet (manufactured by Nippon Pneumatic Mfg. Co., Ltd.), and then classified using an air classifier (MDS-I, manufactured by Nippon Pneumatic Mfg. Co., Ltd.) to obtain resin particles with a volume average particle size of 5 μm and a particle size distribution of 1.2. The obtained resin particles (99 parts) were mixed with 1 part of a fluidizing agent, hydrophobic silica "Aerosil R972" (manufactured by Nippon Aerosil), in a sample mill to obtain a toner.

(4) Toner Evaluation <Low Temperature Fixability (MFT)>
The toner was uniformly applied to the paper surface at 0.6 mg/ ^cm² . The powder was applied to the paper surface using a printer without a thermal fixing unit. Other methods may be used as long as the powder can be uniformly applied at the above weight density. The paper was passed through a pressure roller at a fixing speed (heating roller peripheral speed) of 213 mm/sec and a fixing pressure (pressure roller pressure) of 10 kg/ ^cm² , with the heating roller temperatures ranging from 90 to 230°C in 5°C increments, to create fixed images at each temperature. The presence or absence of cold offset in each fixed image was then visually confirmed, starting with the lowest heating roller temperature, and the temperature at which cold offset no longer occurred is shown in Table 2 as MFT (°C).
The lower the temperature at which cold offset does not occur, the better the low-temperature fixability. Under these evaluation conditions, it is generally preferable that the MFT is 125° C. or less.

<Chargeability> (charge amount)
0.5 g of toner and 10 g of ferrite carrier (F-150, manufactured by Powder Tech Co., Ltd.) were placed in a 50 ml glass bottle, which was then conditioned for 8 hours at 23°C and a relative humidity of 50%. The glass bottle containing the conditioned toner was sealed and set in a Turbler shaker mixer, where it was subjected to friction stirring at 90 rpm for 2 minutes. 0.2 g of the mixed powder after stirring was loaded into a blow-off powder charge amount measuring device equipped with a stainless steel mesh with a mesh size of 20 μm. The charge amount of the remaining ferrite carrier was measured under conditions of a blow pressure of 10 KPa and a suction pressure of 5 KPa, and the charge amount (μC/g) of the toner was calculated by a standard method.
For toner, the higher the negative charge amount, the better the charging characteristics, and it is preferable that the negative charge amount is -15 μC/g or less.
The charge amount was measured using a blow-off charge amount measuring device (manufactured by Toshiba Chemical Co., Ltd.).

<Heat-resistant storage stability> (degree of agglomeration)
1 g of toner and 0.013 g of Aerosil R8200 (manufactured by Evonik Japan Co., Ltd.) were mixed for 1 hour using a shaker, and the mixture was placed in a sealed container and allowed to stand for 48 hours in an atmosphere at a temperature of 45°C and a humidity of 80%. The degree of cohesion was measured using a powder tester, and the heat-resistant storage stability was evaluated.
The lower the value in the cohesion test determined by the following method, the better the heat-resistant storage stability. Under these evaluation conditions, a value of 3% or less is preferred.
Apparatus: Powder Tester model PT-X (manufactured by Hosokawa Micron)
Sieve openings: 355 μm, 250 μm, 150 μm
Vibration width: 1mm
Vibration time: 30 seconds Operation method: Sieves were set on the vibration table of the powder tester in the following order: upper 355 μm, middle 250 μm, and lower 150 μm. 1 g of toner was placed on the upper sieve and vibrated at a vibration amplitude of 1 mm for 30 seconds, and the weight of the toner remaining on each sieve was measured.
Cohesion: Calculated from the weight of the toner used for measurement and the weight of the toner remaining after sieving.
Cohesion degree (%) = (U/N + M/N x 3/5 + L/N x 1/5) x 100
U: Weight of upper layer, M: Weight of middle layer, L: Weight of lower layer, N: Weight of sample (1 g)

<Fixing strength> (Tape peeling)
The fixing strength of the fixed image in the MFT prepared for the evaluation of low-temperature low-adhesion properties was evaluated by a tape peeling test. Tape ("Scotch Mending Tape" manufactured by 3M) was applied to the fixed image, and then the tape was peeled off, and the image density (ID) of the image attached to the tape was measured using a reflection densitometer (trade name "X-Rite Model 404" manufactured by X-Rite). The smaller the image density (numerical value) of the attached image, the higher the fixing strength. Under these evaluation conditions, a value of 0.2 or less is preferable.

<Fixing strength> (pencil hardness)
The MFT-fixed image prepared in the evaluation of low-temperature adhesion was subjected to a scratch hardness test in accordance with JIS K5600-5-4 (1999) by manually scratching the image with a pencil fixed at a 45-degree angle, with a load of 10 g applied from directly above. The image strength was evaluated based on the pencil hardness at which the image was not scratched. The higher the pencil hardness, the better the image strength. Generally, HB or higher is preferred.

As is clear from the results in Table 2 and Figures 1 to 8, the toner binders of Examples 1 and 2 have smaller maximum particle sizes of crystalline polyester in the amorphous polyester, smaller average particle sizes, and better dispersibility than those of Comparative Examples 1 and 2. Furthermore, they also have higher charge amounts, heat-resistant storage stability, and fixing strength.

The toner binder of the present invention can be suitably used as a toner binder for electrophotographic toners used for developing latent images formed in electrophotography, electrostatic recording, electrostatic printing, and the like.
Furthermore, it is suitable for use as an additive for paints, an additive for adhesives, particles for electronic paper, and the like.

Claims (3)

A method for producing a toner binder containing a crystalline polyester (A) and an amorphous polyester (B), wherein the crystalline polyester (A) is a crystalline polyester containing 60 to 100 mol % in total of an aliphatic diol having 2 to 24 carbon atoms and terephthalic acid, based on the total molar number of raw material monomers of (A), the crystalline polyester (A) has an endothermic peak-top temperature (Tm) of 120 to 130°C as measured by a differential scanning calorimeter (DSC), and the method includes a step (1) of kneading the crystalline polyester (A) and the amorphous polyester (B) at a temperature equal to or lower than the endothermic peak-top temperature (Tm) of the crystalline polyester (A), and the difference (Tm - Tk) between the temperature (Tk) at which the crystalline polyester (A) and the amorphous polyester (B) are kneaded in the step (1) and the endothermic peak-top temperature (Tm) of the crystalline polyester (A) is 10 to 50°C . The method for producing a toner binder according to claim 1, wherein the weight ratio (A/B) of the crystalline polyester (A) to the amorphous polyester (B) is 5/95 to 20/80. The method for producing a toner binder according to claim 1, wherein the weight-average molecular weight of the amorphous polyester (B) is 2,000 to 20,000.