JP5622706B2 - Toner for electrostatic latent image development - Google Patents

Description

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

  In general, in electrophotography, the surface of an electrostatic latent image carrier (photoconductor) is charged by corona discharge or the like, and then exposed by a laser or the like to form an electrostatic latent image. The toner image is developed to form a toner image, and the toner image is transferred to a recording medium to obtain a high quality image. Usually, the toner used for forming the toner image is mixed with a binder resin such as a thermoplastic resin, a colorant, a charge control agent, a release agent, etc., kneaded, pulverized, and classified to have an average particle diameter of 5 to 10 μm. Toner particles are used. For the purpose of imparting fluidity to the toner, controlling the charge amount of the toner, and improving the cleaning property of the toner remaining on the photoreceptor without being transferred, inorganic fine particles such as silica and titanium oxide are used. Powder or the like is externally added to the toner.

  As such a toner, a toner having excellent low-temperature fixability is desired as the speed and energy saving of an image forming apparatus are increased. Also, among color toners using colorants of hues such as cyan, magenta, and yellow, for the purpose of forming a higher quality image, the coloring power, transparency, and saturation of the formed image are improved. An excellent toner is desired. From these points, when preparing a color toner that can be fixed at a low temperature, a polyester resin excellent in fixing property at a low temperature and excellent in transparency is often used as a binder resin.

  As a color toner with improved coloring power, transparency, and saturation of the formed image, for example, the average particle diameter of the pigment used as the colorant is in the intrinsic absorption wavelength region of the pigment in the visible light region. A color toner that has been miniaturized so as to have a value that is not less than ½ of the minimum wavelength and not more than ½ of the maximum wavelength is proposed (Patent Document 1).

JP 2003-173048 A

  However, in the toner of Patent Document 1, in order to highly disperse a pigment as a colorant in a binder resin, a pigment that has been previously processed by a method such as a master batch process, an acid paste process, or a flushing process is used. It is what was used. Each of these pigment processing methods involves complicated steps, and there is a problem that the cost of the toner is increased. In particular, in the acid paste processing, a strong acid such as sulfuric acid is used as a processing agent, so that there is a risk of corroding metal parts in the image forming apparatus or a part of the pigment is sulfonated. There is a problem of affecting the chargeability of the. Furthermore, since the toner described in Patent Document 1 is not designed in consideration of low-temperature fixability, it may be inferior in low-temperature fixability depending on the composition and types of components contained in the toner.

  The present invention has been made in view of such circumstances, and has a favorable yellow hue with no turbidity and can form an image having a desired density, regardless of whether or not the pigment as a colorant is highly dispersed. An object of the present invention is to provide a toner for developing an electrostatic latent image that is excellent in low-temperature fixability.

  The present inventors, among color toners, use a polyester resin as a binder resin in a yellow toner having at least a colorant and a release agent in a binder resin and having a bottom of a transmission spectrum between wavelengths of 400 to 500 nm. The first straight-chain saturated carboxylic acid ester compound having 32 to 41 carbon atoms, the second straight-chain saturated carboxylic acid ester compound having 42 to 46 carbon atoms, and the third having 47 to 62 carbon atoms. The release agent containing the linear saturated carboxylic acid ester compound of the above, the content of the first linear saturated carboxylic acid ester compound with respect to the total amount of the release agent is 5 to 45% by mass, the second linear The content of the saturated carboxylic acid ester compound is set to 20 to 70% by mass, and the content of the third linear saturated carboxylic acid ester compound is set to 15 to 45% by mass to solve the above problem. It found that kill, which resulted in the completion of the present invention. Specifically, the present invention provides the following.

(1) An electrostatic latent image developing toner comprising at least a colorant and a release agent in a binder resin and having a transmission spectrum bottom between wavelengths of 400 to 500 nm,
The binder resin is a polyester resin,
The release agent includes a first linear saturated carboxylic acid ester compound having 32 to 41 carbon atoms, a second linear saturated carboxylic acid ester compound having 42 to 46 carbon atoms, and 47 to 62 carbon atoms. A third linear saturated carboxylic acid ester compound,
The content of the first linear saturated carboxylic acid ester compound is 5 to 45% by mass, and the content of the second linear saturated carboxylic acid ester compound is 20 to 70% by mass with respect to the total amount of the release agent. The toner for developing an electrostatic latent image, wherein the content of the third linear saturated carboxylic acid ester compound is 15 to 45% by mass.

  (2) The electrostatic latent image developing toner according to (1), wherein a dispersion diameter of the release agent in the binder resin is 50 to 250 nm.

  According to the present invention, an excellent yellow hue without turbidity can be formed regardless of whether or not a pigment as a colorant is highly dispersed, an image having a desired density can be formed, and a low temperature fixability is excellent. An electrostatic latent image developing toner can be provided.

It is a graph which shows the relationship between the dispersion diameter of the wax and the transmittance | permeability in the bottom of the transmission spectrum in wavelength 400-500 nm in the toner of Example 1 , Example 2, Reference Example 1 , and Comparative Examples 1-7. 6 is a graph showing the relationship between the wax dispersion diameter and the image density in the toners of Example 1 , Example 2, Reference Example 1 and Comparative Examples 1-7.

  Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the object of the present invention. . In addition, although description may be abbreviate | omitted suitably about the location where description overlaps, the summary of invention is not limited.

  The toner for developing an electrostatic latent image (hereinafter also referred to as toner) of the present invention contains at least a colorant and a release agent in a binder resin, and has a bottom of the transmission spectrum (transmitting the toner between wavelengths of 400 to 500 nm). Electrostatic latent image developing toner having a minimum ratio of light to be emitted), wherein the binder resin is a polyester resin, and the release agent is a first direct resin having 32 to 41 carbon atoms. A chain saturated carboxylic acid ester compound, a second linear saturated carboxylic acid ester compound having 42 to 46 carbon atoms, and a third linear saturated carboxylic acid ester compound having 47 to 62 carbon atoms. The content of the first linear saturated carboxylic acid ester compound is 5 to 45% by mass, and the content of the second linear saturated carboxylic acid ester compound is 20 to 70% by mass with respect to the total amount of the mold agent. The third straight chain The content of the sum carboxylic acid ester compound is 15 to 45 wt%, a toner for electrostatic latent image development. The toner of the present invention may be one having an external additive attached to the surface thereof. Furthermore, the toner of the present invention can be mixed with a carrier and used as a two-component developer. Hereinafter, the production method of the binder resin, the colorant, the charge control agent, the release agent, the external additive, the carrier when the toner is a two-component developer, and the electrostatic latent image developing toner will be described in order.

[Binder resin]
The electrostatic latent image developing toner of the present invention uses a polyester resin as a binder resin. As the polyester resin, those obtained by condensation polymerization or co-condensation polymerization of an alcohol component and a carboxylic acid component can be used. The components used when synthesizing the polyester resin include the following alcohol components and carboxylic acid components.

  A divalent or trivalent or higher alcohol can be used as the alcohol component. Specific examples of the divalent or trivalent or higher alcohol component include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1 Diols such as 1,4-butenediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol; bisphenol A, Bisphenols such as hydrogenated bisphenol A, polyoxyethylenated bisphenol A, polyoxypropylenated bisphenol A; sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, Entaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, diglycerol, 2-methylpropanetriol, 2-methyl-1,2,4- Examples include trivalent or higher alcohols such as butanetriol, trimethylolethane, trimethylolpropane, and 1,3,5-trihydroxymethylbenzene.

  As the carboxylic acid component, a divalent or trivalent or higher carboxylic acid can be used. Specific examples of the divalent or trivalent or higher carboxylic acid component include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, Sebacic acid, azelaic acid, malonic acid, or n-butyl succinic acid, n-butenyl succinic acid, isobutyl succinic acid, isobutenyl succinic acid, n-octyl succinic acid, n-octenyl succinic acid, n-dodecyl succinic acid, n-dodecenyl succinic acid Divalent carboxylic acids such as acids, isododecyl succinic acid, isododecenyl succinic acid and the like or alkyl or alkenyl succinic acid; 1,2,4-benzenetricarboxylic acid (trimellitic acid), 1,2,5-benzenetricarboxylic acid Acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphtha Tricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid , Tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, emporic trimer acid, and other trivalent or higher carboxylic acids. These divalent or trivalent or higher carboxylic acid components may be used as ester-forming derivatives such as acid halides, acid anhydrides, and lower alkyl esters. Here, “lower alkyl” means an alkyl group having 1 to 6 carbon atoms.

  The softening point of the polyester resin is preferably 80 to 150 ° C, more preferably 90 to 140 ° C.

[Colorant]
The toner for developing an electrostatic latent image of the present invention is a toner for developing an electrostatic latent image having a bottom of a transmission spectrum at a wavelength of 400 to 500 nm, and therefore contains a yellow pigment. The yellow pigment is not particularly limited as long as it is conventionally used as a colorant for toner. Yellow lead, zinc yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow, Navels Yellow pigments such as yellow, naphthol yellow S, Hansa yellow G, Hansa yellow 10G, benzidine yellow G, benzidine yellow GR, quinoline yellow lake, permanent yellow NCG, tartrazine lake, and pigment yellow 180 can be used. Among these pigments, Pigment Yellow 180 is more preferable in terms of excellent color developability.

  The amount of the colorant used is not particularly limited as long as the object of the present invention is not impaired. Specifically, 1-10 mass parts is preferable with respect to 100 mass parts of binder resin, and 3-7 mass parts is more preferable.

  The toner for developing an electrostatic latent image of the present invention may contain a small amount of a colorant of other colors for the purpose of adjusting the hue. Specific examples of other colorants for yellow include black pigments such as carbon black, acetylene black, lamp black and aniline black; red lead yellow lead, molybdenum orange, permanent orange GTR, pyrazolone orange, vulcan orange, and induslen brilliant. Orange pigments such as orange GK; Bengala, cadmium red, red lead, mercury cadmium sulfide, permanent red 4R, resol red, pyrazolone red, watching red calcium salt, lake red D, brilliant carmine 6B, eosin lake, rhodamine lake B, Red pigments such as Alizarin Lake, Brilliant Carmine 3B, Pigment Red 122, Pigment Red 202; Bitumen, Cobalt Blue, Alkaline Blue Lake, Victoria Blue Partial Chlorine , Blue pigments such as First Sky Blue, Pigment Blue 15 and Induslen Blue BC; Purple pigments such as Manganese Purple, Fast Violet B, Methyl Violet Lake; Chrome Green, Chrome Oxide, Pigment Green B, Malachite Green Lake, Final Yellow Green pigments such as green G; white pigments such as zinc white, titanium oxide, antimony white, and zinc sulfide; extender pigments such as barite powder, barium carbonate, clay, silica, white carbon, talc, and alumina white. These colorants may be used in combination of two or more for the purpose of adjusting the toner to a desired hue.

  The amount of the colorant used for other colors of yellow is not particularly limited as long as the object of the present invention is not impaired. Typically, 5 to 10 parts by mass is preferable and 7 to 8 parts by mass is more preferable with respect to 100 parts by mass of the yellow pigment.

(Charge control agent)
The toner for developing an electrostatic latent image of the present invention may contain a charge control agent in the binder resin as necessary. The purpose of the charge control agent is to improve the charge level of the toner and the charge start-up characteristic that is an indicator of whether or not the toner can be charged to a predetermined charge level in a short time, and to obtain a toner having excellent durability and stability. used. When developing with positively charged toner, a positively chargeable charge control agent is used. When developing with negatively charged toner, a negatively chargeable charge control agent is used.

  The type of the charge control agent is not particularly limited as long as the object of the present invention is not impaired, and can be appropriately selected from charge control agents conventionally used in toners. Specific examples of the positively chargeable charge control agent include pyridazine, pyrimidine, pyrazine, orthooxazine, metaoxazine, paraoxazine, orthothiazine, metathiazine, parathiazine, 1,2,3-triazine, 1,2,4-triazine, 1,3,5-triazine, 1,2,4-oxadiazine, 1,3,4-oxadiazine, 1,2,6-oxadiazine, 1,3,4-thiadiazine, 1,3,5-thiadiazine, 1, 2,3,4-tetrazine, 1,2,4,5-tetrazine, 1,2,3,5-tetrazine, 1,2,4,6-oxatriazine, 1,3,4,5-oxatriazine, Azine compounds such as phthalazine, quinazoline, quinoxaline; azine fast red FC, azine fast red 12BK, azine violet BO, azine Direct dyes composed of azine compounds such as Raun 3G, azine light brown GR, azine dark green BH / C, azine deep black EW, and azine deep black 3RL; nigrosine compounds such as nigrosine, nigrosine salts, nigrosine derivatives; Acid dyes comprising nigrosine compounds such as BK, nigrosine NB, and nigrosine Z; metal salts of naphthenic acid or higher fatty acids; alkoxylated amines; alkylamides; quaternary ammonium salts such as benzylmethylhexyldecylammonium and decyltrimethylammonium chloride It is done. Among these positively chargeable charge control agents, a nigrosine compound is particularly preferable in that a more rapid start-up property can be obtained. These positively chargeable charge control agents can be used in combination of two or more.

  Quaternary ammonium salts, carboxylates, or resins having a carboxyl group as a functional group can also be used as a positively chargeable charge control agent. More specifically, a styrene resin having a quaternary ammonium salt, an acrylic resin having a quaternary ammonium salt, a styrene-acrylic resin having a quaternary ammonium salt, a polyester resin having a quaternary ammonium salt, a carboxylic acid Styrene resin having salt, acrylic resin having carboxylate, styrene-acrylic resin having carboxylate, polyester resin having carboxylate, styrene resin having carboxyl group, acrylic having carboxyl group 1 type, or 2 or more types, such as resin, the styrene-acrylic resin which has a carboxyl group, and the polyester-type resin which has a carboxyl group, are mentioned. The molecular weight of these resins is not particularly limited as long as the object of the present invention is not impaired, and may be an oligomer or a polymer.

  Among resins that can be used as a positively chargeable charge control agent, a styrene-acrylic copolymer having a quaternary ammonium salt as a functional group from the viewpoint that the charge amount can be easily adjusted to a value within a desired range. A resin is more preferable. Specific examples of preferable acrylic comonomers to be copolymerized with styrene units in a styrene-acrylic copolymer resin having a quaternary ammonium salt as a functional group include methyl acrylate, ethyl acrylate, n-propyl acrylate, and acrylic acid. (Meth) such as iso-propyl, n-butyl acrylate, iso-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, iso-butyl methacrylate Examples include alkyl acrylates.

  As the quaternary ammonium salt, a unit derived from a dialkylaminoalkyl (meth) acrylate, dialkyl (meth) acrylamide, or dialkylaminoalkyl (meth) acrylamide through a quaternization step is used. Specific examples of the dialkylaminoalkyl (meth) acrylate include dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dipropylaminoethyl (meth) acrylate, dibutylaminoethyl (meth) acrylate and the like. Specific examples of dialkyl (meth) acrylamide include dimethylmethacrylamide, and specific examples of dialkylaminoalkyl (meth) acrylamide include dimethylaminopropylmethacrylamide. Further, hydroxy group-containing polymerizable monomers such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and N-methylol (meth) acrylamide can be used in combination during polymerization.

  Specific examples of the negatively chargeable charge control agent include organometallic complexes and chelate compounds. Examples of organometallic complexes and chelate compounds include acetylacetone metal complexes such as aluminum acetylacetonate and iron (II) acetylacetonate, and salicylic acid metal complexes or salicylic acid systems such as chromium 3,5-di-tert-butylsalicylate. Metal salts are preferable, and salicylic acid metal complexes or salicylic acid metal salts are more preferable. These negatively chargeable charge control agents can be used in combination of two or more.

  The amount of the positively or negatively chargeable charge control agent used is not particularly limited as long as the object of the present invention is not impaired. The amount of the positively or negatively chargeable charge control agent used is typically preferably 1.5 to 15 parts by mass, and 2.0 to 8.0 parts by mass when the total amount of toner is 100 parts by mass. Part is more preferable, and 3.0 to 7.0 parts by weight is particularly preferable. When the amount of the charge control agent used is too small, it is difficult to stably charge the toner to a predetermined polarity, so that the image density of the formed image may be lowered or the image density may not be maintained for a long time. In such a case, the charge control agent is difficult to uniformly disperse in the toner, and fogging in the formed image and contamination of the latent image carrier due to the toner are likely to occur. When the amount of the charge control agent used is excessive, charging failure of the toner under high temperature and high humidity is likely to occur due to deterioration of environmental resistance. As a result, image defects in the formed image, and latent image carrying portion due to the toner Contamination is likely to occur.

〔Release agent〕
The toner for developing an electrostatic latent image contains a release agent for the purpose of improving the fixability of the toner and suppressing the occurrence of offset in the formed image. The toner for developing an electrostatic latent image of the present invention includes a first linear saturated carboxylic acid ester compound having 32 to 41 carbon atoms and a second linear saturated compound having 42 to 46 carbon atoms in a binder resin. A carboxylic acid ester compound and a third linear saturated carboxylic acid ester compound having 47 to 62 carbon atoms, wherein the content of the first linear saturated carboxylic acid ester compound is 5 with respect to the total amount of the release agent. -45 mass%, the content of the second linear saturated carboxylic acid ester compound is 20-70 mass%, and the content of the third linear saturated carboxylic acid ester compound is 15-45 mass%. Contains a release agent.

  The total content of the first to third linear saturated carboxylic acid ester compounds in the release agent is such that the content of the first to third linear saturated carboxylic acid ester compounds in the release agent is a predetermined amount. Although it does not specifically limit as much as possible, 80 mass% or more is preferable, 90 mass% or more is more preferable, and it is especially preferable that it is 100%. The release agent that the release agent can contain in addition to the first to third linear saturated carboxylic acid ester compounds is not particularly limited as long as the object of the present invention is not impaired, and has been conventionally used for toners. It can be used by appropriately selecting from release agents. Specific examples of other mold release agents for the first to third linear saturated carboxylic acid ester compounds include polyethylene wax, polypropylene wax, fluororesin wax, Fischer-Tropsch wax, paraffin wax, montan wax, rice wax and the like. Can be mentioned.

  The amount of the release agent used in the electrostatic latent image developing toner is not particularly limited as long as the object of the present invention is not impaired. Typically, 1 to 20 parts by mass is preferable and 2 to 10 parts by mass is more preferable with respect to 100 parts by mass of the binder resin. If the amount of the release agent used is too small, the desired effect of improving the toner fixing property and suppressing the occurrence of offset in the formed image cannot be obtained, or a yellow hue with a good hue without turbidity is exhibited. In some cases, it may be difficult to obtain a toner capable of forming an image having a desired density. When the amount of the release agent used is excessive, the amount of the release agent released from the binder resin may increase, and the toner may be easily blocked.

  Here, the number of carbon atoms of the ester compound such as the first linear saturated carboxylic acid ester compound, the second linear saturated carboxylic acid ester compound, and the third linear saturated carboxylic acid ester compound is each ester compound. The total number of carbon atoms contained in one molecule is shown. Specifically, in the case of a carboxylic acid ester compound obtained by reacting a carboxylic acid and an alcohol, the total is the number of carbon atoms derived from the carboxylic acid and the number of carbon atoms derived from the alcohol. More specifically, for example, the carboxylic acid ester compound obtained by reacting octadecanoic acid having 18 carbon atoms with octadecanol having 18 carbon atoms has 36 carbon atoms and 18 carbon atoms. The number of carbon atoms of the carboxylic acid ester compound obtained by reacting the octadecanoic acid with nonadecanol having 19 carbon atoms is 37.

  The first linear saturated carboxylic acid ester compound has the lowest number of carbon atoms among the three types of carboxylic acid ester compounds, and thus has a low melting point, and preferably acts as a release agent even at a low fixing temperature. Therefore, the release agent contains 5 to 45% by mass of the first linear saturated carboxylic acid ester compound in the binder resin with respect to the total amount of the release agent, thereby ensuring low-temperature fixability of the toner. The occurrence of offset in the formed image can be suppressed.

  On the other hand, when the first linear saturated carboxylic acid ester compound is a polyester resin, if it is contained in a large amount, it tends to be difficult to disperse in the toner. For this reason, when the content of the first linear saturated carboxylic acid ester compound in the release agent is excessive, the release agent is dispersed in the binder resin with a suitable dispersion diameter (preferably 50 to 250 nm). It is difficult to obtain a toner that exhibits a yellow hue with a good hue without turbidity and can form an image with a desired density. In addition, since the first linear saturated carboxylic acid ester compound has a low melting point, when the content of the first linear saturated carboxylic acid ester compound is excessive, the first direct saturated carboxylic acid ester compound is stored when the toner is stored at a high temperature. When the chain saturated carboxylic acid ester compound exudes from the binder resin, the storage stability of the toner tends to be lowered.

  Since the third straight-chain saturated carboxylic acid ester compound has the largest number of carbon atoms among the three carboxylic acid ester compounds, the third linear saturated carboxylic acid ester compound has a temperature at which the binder resin, release agent, etc. are melt-kneaded in the toner preparation. High viscosity. For this reason, a mold release agent contains 15-45 mass% 3rd linear saturated carboxylic acid ester compound, and a mold release agent is a suitable dispersion diameter (preferably 50-250 nm) in binder resin. Easy to disperse well. In addition, by setting the dispersion diameter of the release agent in the binder resin to 50 to 250 nm, light having a wavelength of 400 to 500 nm is favorably absorbed, exhibits a yellow hue with a good hue without turbidity, and has a desired concentration. It is easy to obtain a toner that can form an image. In addition, since the third linear saturated carboxylic acid ester compound has a high melting point, the storage stability of the toner at a high temperature can be improved.

  The second linear saturated carboxylic acid ester compound has an intermediate number of carbon atoms between the first linear saturated carboxylic acid ester compound and the third linear saturated carboxylic acid ester compound. It has high affinity with both the chain saturated carboxylic acid ester compound and the third linear saturated carboxylic acid ester compound. For this reason, when a mold release agent contains 20-70 mass% of 2nd linear saturated carboxylic acid ester compound, the 1st-3rd linear saturated carboxylic acid ester compound tends to be compatibilized favorably. For this reason, when content of the 2nd linear saturated carboxylic acid ester compound in a mold release agent is too small, the 1st-3rd linear saturated carboxylic acid ester compound is not compatibilized well, and binder resin In some cases, the dispersion diameter of the release agent in the inside becomes large. In such a case, it is difficult to obtain a toner capable of forming an image having a desired density.

  The release agent contained in the electrostatic latent image developing toner is a carboxylic acid ester compound having 44 carbon atoms among the second straight-chain saturated carboxylic acid ester compounds. It is more preferable to contain -47 mass%. In such a case, it is easy to obtain a toner that is excellent in low-temperature fixability and high-temperature storage stability and hardly causes an offset in the formed image.

  The number of carbon atoms of the carboxylic acid ester compound contained in the release agent, and the content of the carboxylic acid ester compound of that number of carbon atoms relative to the total amount of the release agent, that is, the carbon atoms of the carboxylic acid ester compound contained in the release agent The number distribution can be measured using, for example, a gas chromatograph apparatus. Specifically, for example, GC-14B (manufactured by Shimadzu Corporation) is used as the gas chromatograph apparatus, Ultra ALLOY UA17-15M-0.25F (manufactured by Frontier Laboratories) is used as the column, and the column temperature is determined. By raising the starting temperature from 150 ° C. to 320 ° C. at 10 ° C./min, holding the column temperature at the same temperature for 33 minutes, and analyzing the sample of the release agent at an injection temperature of 350 ° C. and a detection temperature of 350 ° C. The carbon atom number distribution of the release agent can be obtained.

  In addition, the mold release agent includes a linear saturated monocarboxylic acid having 16 to 34 carbon atoms and a carbon atom number of 16 to 16 in a range including a predetermined amount of the first to third linear saturated carboxylic acid ester compounds. It preferably contains a carboxylic acid ester compound obtained by esterifying 34 linear saturated monoalcohols.

  The linear saturated monocarboxylic acid is not particularly limited as long as it is a linear saturated monocarboxylic acid having 16 to 34 carbon atoms. Specific examples of the linear saturated monocarboxylic acid having 16 to 34 carbon atoms include palmitic acid, stearic acid, arachidic acid, behenic acid, tetracosanoic acid, hexacosanoic acid, octacosanoic acid, triacontanoic acid, dotriacontanoic acid, And tetratriacontanoic acid. These linear saturated monocarboxylic acids can be used in combination of two or more.

  The linear saturated monoalcohol is not particularly limited as long as it is a linear saturated monoalcohol having 16 to 34 carbon atoms. Specific examples of the linear saturated monoalcohol having 16 to 34 carbon atoms include palmityl alcohol, stearyl alcohol, eicosyl alcohol, tetracosyl alcohol, hexacosyl alcohol, octacosyl alcohol, triacosyl alcohol, Examples include dotriacosyl alcohol and tetratriacosyl alcohol. These linear saturated monoalcohols can be used in combination of two or more.

  The release agent is not particularly limited as long as it has a predetermined number of carbon atoms, and includes a wax containing a carboxylic acid ester compound such as carnauba wax in addition to the carboxylic acid ester compound prepared by esterification. May be.

  Although the acid value of a mold release agent is not specifically limited in the range which does not inhibit the objective of this invention, It is preferable that it is low. Specifically, the acid value of the release agent is preferably 7 mgKOH / g or less, and more preferably 3 mgKOH / g or less. When the acid value of the release agent is too high, the charging property, high-temperature storage property, and blocking resistance of the toner may be deteriorated due to the influence of the carboxylic acid component contained in the obtained toner. Here, the acid value of the wax for toner is a value measured by a method according to JOCS 2.3.1-96 of “1996 Standard Oil Analysis Test Method” of Japan Oil Chemists' Society.

  Further, the release agent is a carboxylic acid ester compound obtained by esterifying a linear saturated monocarboxylic acid having 16 to 34 carbon atoms and a linear saturated monoalcohol having 16 to 34 carbon atoms. When it contains, it is preferable that the amount of the linear saturated monocarboxylic acid having 24 or less carbon atoms remaining in the release agent is small. Specifically, the content of the linear saturated monocarboxylic acid having 24 or less carbon atoms in the release agent is preferably 2% by mass or less, and more preferably 1% by mass or less. When the content of the linear saturated monocarboxylic acid having 24 or less carbon atoms is too high, the storage stability and blocking resistance of the toner tend to be lowered. Here, the content of the linear saturated monocarboxylic acid having 24 or less carbon atoms in the release agent can be measured using gas chromatography under the same conditions as the carbon atom number distribution of the wax.

  Moreover, 60-82 degreeC is preferable and, as for the transparent melting point of a mold release agent, 65-80 degreeC is more preferable. When the transparent melting point is too low, the storage stability of the toner, particularly the high temperature storage stability, tends to decrease. Further, when the transparent melting point is too high, the low-temperature fixability may be lowered. Here, the transparent melting point of the release agent is a temperature at which the release agent, which is a measurement object, becomes transparent, and is a value measured by a method in accordance with JIS K0064.

  The method for producing the release agent is not particularly limited, and even when a mixture of a plurality of linear saturated carboxylic acid ester compounds having different numbers of carbon atoms, linear saturated carboxylic acids having various numbers of carbon atoms or derivatives thereof are used. It may be synthesized by reacting a mixture containing a linear saturated monoalcohol having various carbon atoms or a mixture containing a derivative thereof. In addition, the method for preparing a plurality of types of carboxylic acid ester compounds having different numbers of carbon atoms is not particularly limited, and each includes one type of linear saturated monocarboxylic acid or derivative thereof and linear saturated monoalcohol or derivative thereof. Examples thereof include a method of preparing a carboxylic acid ester compound by esterification and a method of purifying a wax such as carnauba wax that exists in nature to obtain a carboxylic acid ester compound having a single carbon atom number. Examples of the derivative of the linear saturated monocarboxylic acid used for the synthesis of the carboxylic acid ester compound include acid halides such as acid chlorides. Examples of the linear saturated monoalcohol derivative used for the synthesis of the carboxylic acid ester compound include acetate and propionate. In addition, as a method for purifying a naturally occurring wax, a method of carrying out methods such as extraction, distillation, filtration, crystallization, column chromatography, etc. alone or in combination can be mentioned. A plurality of types of carboxylic acid ester compounds having different numbers of carbon atoms can be used by purchasing a carboxylic acid ester compound having a known number of carbon atoms.

(External additive)
In the toner for developing an electrostatic latent image, an external additive may be attached to the surface of the toner particle for the purpose of improving the fluidity, storage stability, cleaning property, etc. of the toner.

  The type of external additive is not particularly limited as long as it does not impair the object of the present invention, and can be appropriately selected from external additives conventionally used for toners. Specific examples of suitable external additives include silica and metal oxides such as alumina, titanium oxide, magnesium oxide, zinc oxide, strontium titanate, and barium titanate. These external additives can be used in combination of two or more.

The particle diameter of the external additive is not particularly limited as long as the object of the present invention is not impaired, and typically 0.01 to 1.0 μm is preferable.
The volume specific resistance value of the external additive can be adjusted by forming a coating layer made of tin oxide and antimony oxide on the surface of the external additive and changing the thickness of the coating layer and the ratio of tin oxide to antimony oxide. .

  The amount of the external additive used for the toner particles is not particularly limited as long as the object of the present invention is not impaired. Typically, the amount of the external additive used is preferably 0.1 to 10 parts by mass, and more preferably 0.2 to 5 parts by mass with respect to 100 parts by mass of the toner before being processed with the external additive. When the external additive is used in such an amount, it is easy to obtain a toner excellent in fluidity, storage stability, and cleaning properties.

  As the external additive, one whose surface is treated with a hydrophobizing agent can be used. In the case of using a hydrophobized external additive, it is easy to suppress a decrease in charge amount of the toner under high temperature and high humidity, and it is easy to obtain a toner having excellent fluidity. As the hydrophobizing agent, for example, an aminosilane coupling agent can be used. Specific examples of the aminosilane coupling agent include γ-aminopropyltriethoxysilane, γ-aminopropylmethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, γ- (2-aminoethyl). -Γ-aminopropylmethyldimethoxysilane, γ-anilinopropyltrimethoxysilane and the like. In order to supplement the hydrophobizing effect, an aminosilane coupling agent and a hydrophobizing agent other than the aminosilane coupling agent can be used in combination. As the hydrophobizing agent other than the aminosilane coupling agent, hexamethyldisilazane is preferably used because of its excellent hydrophobizing effect and toner fluidity improving effect.

  Silicone oil can also be used as a hydrophobizing agent for external additives. The type of silicone oil is not particularly limited as long as a desired hydrophobizing effect is obtained, and various silicone oils conventionally used as a hydrophobizing agent can be used. As the silicone oil, those having a linear siloxane structure are preferable, and any of non-reactive silicone oil and reactive silicone oil can be used. Specific examples of silicone oils include dimethyl silicone oil, phenylmethyl silicone oil, chlorophenyl silicone oil, alkyl silicone oil, chlorosilicone oil, polyoxyalkylene modified silicone oil, fatty acid ester modified silicone oil, methyl hydrogen silicone oil, silanol group-containing Examples include silicone oil, alkoxy group-containing silicone oil, acetoxy group-containing silicone oil, amino-modified silicone oil, carboxylic acid-modified silicone oil, alcohol-modified silicone oil, and the like.

  As a method of hydrophobizing the external additive, a method of dropping or spraying a hydrophobizing agent such as aminosilane or silicone oil while stirring the external additive at a high speed, or an organic solvent of the hydrophobizing agent being stirred. The method of adding an external additive in a solvent solution is mentioned. The external additive subjected to the hydrophobization treatment is obtained by heating after the hydrophobization treatment. When the hydrophobizing agent is dropped or sprayed, the hydrophobizing agent can be used as it is or diluted with an organic solvent or the like.

[Carrier]
The toner for developing an electrostatic latent image can be mixed with a desired carrier and used as a two-component developer. When preparing a two-component developer, it is preferable to use a magnetic carrier.

  Suitable carriers when the electrostatic latent image developing toner is a two-component developer include those in which a carrier core material is coated with a resin. Specific examples of carrier core materials include particles of iron, oxidized iron, reduced iron, magnetite, copper, silicon steel, ferrite, nickel, cobalt, etc., and particles of alloys of these materials with manganese, zinc, aluminum, etc. , Particles such as iron-nickel alloy, iron-cobalt alloy, titanium oxide, aluminum oxide, copper oxide, magnesium oxide, lead oxide, zirconium oxide, silicon carbide, magnesium titanate, barium titanate, lithium titanate, lead titanate , Ceramic particles such as lead zirconate and lithium niobate, particles of high dielectric constant materials such as ammonium dihydrogen phosphate, potassium dihydrogen phosphate, and Rochelle salt, resin carriers in which the above magnetic particles are dispersed in a resin, etc. Is mentioned.

  Specific examples of the resin covering the carrier core material include (meth) acrylic polymers, styrene polymers, styrene- (meth) acrylic copolymers, olefin polymers (polyethylene, chlorinated polyethylene, polypropylene, etc. ), Polyvinyl chloride, polyvinyl acetate, polycarbonate, cellulose resin, polyester resin, unsaturated polyester resin, polyamide resin, polyurethane resin, epoxy resin, silicone resin, fluororesin (polytetrafluoroethylene, polychlorotrifluoroethylene, polyfluoride) Vinylidene chloride, etc.), phenol resin, xylene resin, diallyl phthalate resin, polyacetal resin, amino resin and the like. These resins can be used in combination of two or more.

  The particle diameter of the carrier is not particularly limited as long as the object of the present invention is not impaired, but is preferably 20 to 120 μm, more preferably 25 to 80 μm, as measured by an electron microscope.

The apparent density of the carrier is not particularly limited as long as the object of the present invention is not impaired. The apparent density varies depending on the carrier composition and surface structure, but typically 2000 to 2500 kg / m ³ is preferable.

  When the electrostatic latent image developing toner of the present invention is used as a two-component developer, the toner content is preferably 3 to 20% by mass, and more preferably 5 to 15% by mass, based on the mass of the two-component developer. . By setting the toner content in the two-component developer within such a range, it is possible to maintain an appropriate image density of the formed image, and to suppress contamination of the image forming apparatus and adhesion of the toner to the transfer paper by suppressing toner scattering. it can.

[Method for producing toner for developing electrostatic latent image]
The toner for developing an electrostatic latent image is obtained by blending a binder resin with a colorant, a release agent, and, if necessary, an optional component such as a charge control agent, and then pulverizing and classifying the desired particle size. It is obtained by adjusting. The toner for developing an electrostatic latent image may be one having an external additive attached to the surface thereof as necessary.

  A method for producing a toner by blending a binder resin with a colorant, a release agent, and components such as charge control as necessary is not particularly limited as long as these components can be well dispersed in the binder resin. . As a specific example of a preferable toner production method, a binder resin and components such as a colorant, a release agent, and a charge control agent are mixed by a mixer or the like, and then a kneader such as a single-screw or twin-screw extruder. There is a method of melt-kneading the binder resin and the components blended in the binder resin by pulverizing and classifying the cooled kneaded product. The average particle size of the toner is not particularly limited as long as the object of the present invention is not impaired, but generally 5 to 10 μm is preferable.

  In the toner for developing an electrostatic latent image of the present invention, the dispersion diameter of the release agent in the binder resin is preferably in the range of 50 to 250 nm. The dispersion diameter of the release agent in the binder resin can be adjusted by appropriately changing the melt-kneading conditions. For example, by changing the screw pattern of the extruder to a pattern with a high kneading effect, the dispersion diameter of the release agent can be reduced, and by changing the screw pattern to a pattern with a low kneading effect, the dispersion diameter of the release agent Can be increased. Further, the dispersion diameter of the release agent can be reduced by lowering the cylinder temperature, and the dispersion diameter of the release agent can be increased by increasing the cylinder temperature. This is because the higher the cylinder temperature, the softer the mixture in the extruder and the less the shearing force is applied to the mixture.

The dispersion diameter of the release agent in the binder resin can be measured by the following method.
<Method for measuring wax dispersion diameter>
A toner or a melt-kneaded product obtained at the time of preparation of the toner is used as a sample. When the sample is a toner, the resin mass is prepared by embedding the toner in an embedding resin for electron microscope observation. When the sample is a melt-kneaded product, for example, the melt-kneaded product is rolled by a rolling device such as a drum flaker (manufactured by Nippon Coke Kogyo Co., Ltd.) to obtain a sheet. From the resulting resin mass or sheet, a flake is prepared by a microtome (EM UC6 (manufactured by Leica)). The thin piece is observed with a transmission electron microscope (JSM-7401F (manufactured by JEOL Ltd.)) at a magnification of 3000 times, and the dispersion diameter of the wax is measured from the scale of the image. The dispersion diameter of the wax is measured for five or more dispersed particles, and the average value of the measured dispersion diameter is defined as the dispersion diameter of the wax. When the sample is toner, the average diameter is obtained by measuring the diameter of the dispersed particles of the wax one by one for any five or more toners. There is no large variation in the diameter of the dispersed particles of the wax, and an average diameter having no problem can be calculated by measuring five or more dispersed particles.

  Further, the method of attaching the external additive to the toner surface is not particularly limited, and can be appropriately selected from conventionally known methods. Specifically, the processing conditions are adjusted so that the particles of the external additive are not embedded in the toner, and the processing with the external additive is performed by a mixer such as a Henschel mixer or a Nauter mixer.

  The electrostatic latent image developing toner of the present invention described above has a good yellow hue with no turbidity and can form an image with a desired density regardless of whether or not the pigment as a colorant is highly dispersed. In addition, since it has excellent low-temperature fixability, it is used for color image development in various image forming apparatuses.

  Hereinafter, the present invention will be described more specifically with reference to examples. In addition, this invention is not limited at all by the Example.

[Preparation Example 1]
(Preparation of first linear saturated carboxylic acid ester compound to third linear saturated carboxylic acid ester compound)
The first linear saturated carboxylic acid ester compound (wax 1) having 32 to 41 carbon atoms, carbon atoms according to the following method using the saturated aliphatic monocarboxylic acid and the saturated aliphatic monoalcohol listed in Table 1. A second linear saturated carboxylic acid ester compound (wax 2) having a number of 42 to 46 and a third linear saturated carboxylic acid ester compound having a carbon atom number of 47 to 62 (wax 3) were prepared.

  In a four-necked flask equipped with a thermometer, a nitrogen introducing tube, a stirring device, and a cooling tube, 1.34 mol of a monocarboxylic acid having a composition (carbon atom number distribution) shown in Table 1 and 1.27 mol of a monoalcohol Was added so that the total amount of monocarboxylic acid and monoalcohol was 850 g. Under a nitrogen stream, the temperature of the reaction mixture was raised to 220 ° C., and the reaction was carried out at atmospheric pressure for 15 hours while distilling off water as a byproduct. To the obtained crude ester compound was added 20 g of toluene, 4 g of ethanol, and an aqueous potassium hydroxide solution having a concentration of 10% by mass corresponding to 1.5 times equivalent of the acid value of the crude ester compound, and stirred at 70 ° C. for 30 minutes. After leaving still and isolate | separating into the upper layer and the lower layer, the lower layer (water layer) was removed and the crude ester compound was washed with water. This water washing operation was repeated until the pH of the lower layer (water layer) became neutral. The crude ester compound after washing with water was heated to 180 ° C. under a reduced pressure of 1 kPa to distill off the solvent, and then the molten ester compound was filtered to obtain a carboxylic acid ester compound.

  When the distribution of the number of carbon atoms of the waxes 1 to 3 was measured by the following method, the wax 1 contained only a carboxylic acid ester compound having 32 to 41 carbon atoms, and the wax 2 had a number of carbon atoms of 42 to 46. Only the carboxylic acid ester compound was contained, and the wax 3 contained only the carboxylic acid ester compound having 47 to 62 carbon atoms.

<Method for measuring carbon atom number distribution>
The measurement was performed using GC-14B (manufactured by Shimadzu Corporation) as a gas chromatograph apparatus and Ultra ALLOY UA17-15M-0.25F (manufactured by Frontier Laboratories) as a column. The column temperature was raised from an initial temperature of 150 ° C. to 320 ° C. at 10 ° C./min, the column temperature was maintained at the same temperature for 33 minutes, and the sample was analyzed at an injection temperature of 350 ° C. and a detection temperature of 350 ° C.

  Table 1 shows the content of the monocarboxylic acid and monoalcohol for each carbon atom in the monocarboxylic acid and monoalcohol used for the synthesis of wax 1 to wax 3. In addition, content of monocarboxylic acid and monoalcohol of Table 1 is the mass% with respect to the total mass of monocarboxylic acid or monoalcohol.

[Preparation Example 2]
Wax 1 to wax 3 obtained in Preparation Example 1 were mixed at a ratio (mass%) shown in Table 2 to obtain wax A to wax J.

[Example 1]
100 parts by mass of a polyester resin (manufactured by Sanyo Kasei Kogyo Co., Ltd.), 5 parts by mass of a yellow pigment (PY 180 (manufactured by Sanyo Dye), Pigment Yellow 180), a charge control agent (quaternary ammonium salt, P- 51 (manufactured by Orient Chemical Co., Ltd.)) and 5 parts by mass of wax A were mixed with a Henschel mixer (20B (manufactured by Mitsui Mining Co., Ltd.)) for 5 minutes at a rotational speed of 2500 rpm. The obtained mixture was melt-kneaded in a twin-screw extruder (PCM-30 (manufactured by Ikegai Co., Ltd.)) under the conditions of a rotation speed of 200 rpm, a cylinder temperature of 120 ° C., and an input amount of 6 kg / h, and then kneaded in a molten state. The product was cooled and solidified by a drum flaker (manufactured by Mitsui Mining Co., Ltd.) under conditions of a processing speed of 140 mm / second and a plate thickness of 3 to 4 mm. The solidified kneaded product was coarsely pulverized by a pulverizer (Rotoplex (manufactured by Alpine)) having a screen opening of 2 mm, and then finely pulverized by a pulverizer (turbo mill T-250 type (manufactured by Turbo Kogyo Co., Ltd.)). The resulting finely pulverized product was classified by an airflow classifier (Alpine classifier (manufactured by Alpine)) to obtain a pulverized product having a volume average particle diameter of 7 μm. 100 parts by mass of the obtained pulverized product and 0.8 parts by mass of silica (H2050EP (manufactured by Wacker)) are added to a Henschel mixer (20B (manufactured by Mitsui Mining Co., Ltd.)) and mixed for 3 minutes under the condition of 2500 rpm. Thus, a toner was obtained.

  The obtained toner was evaluated for wax dispersion diameter, transmittance, image density, and fixability according to the following method. Table 3 shows the evaluation results of the toner of Example 1.

<Method for measuring wax dispersion diameter>
The melt-kneaded material obtained at the time of toner preparation was used as a sample. The melt-kneaded material was rolled with a drum flaker (manufactured by Nippon Coke Kogyo Co., Ltd.) to obtain a sheet. From the obtained sheet, a thin piece was prepared by a microtome (EM UC6 (manufactured by Leica)). The thin piece was observed with a transmission electron microscope (JSM-7401F (manufactured by JEOL Ltd.)) at a magnification of 3000 times, and the dispersion diameter of the wax was measured from the scale of the image. The wax dispersion diameter was measured for 5 or more dispersed particles, and the average value of the measured dispersion diameters was defined as the wax dispersion diameter.

<Transmittance measurement method>
5-6 mg of toner was placed on the slide glass, and another slide glass was placed on the slide glass to sandwich the toner. Two glass slides with toner sandwiched between them are placed on a heatable stage installed on a press machine, and the stage is heated to a temperature of 100 to 120 ° C., and a pressure of 4 to 6 MPa (G). Was applied to the slide glass for 20 to 30 seconds, and the toner sample between the slide glasses was pressed to prepare a sample for transmittance measurement. Using the obtained sample, a transmission spectrum (ratio of light dropping toner) at a wavelength of 400 to 500 nm was measured with a spectrophotometer (UV-3100 (manufactured by Shimadzu Corporation)), and at the bottom of the transmission spectrum. The light transmittance with respect to the toner was determined.

<Image density>
The toner of Example 1 and a ferrite carrier (a carrier used in a printer (FS-C5200DN) manufactured by Kyocera Mita Corporation) were mixed so that the toner concentration in the two-component developer was 10% by mass. . The obtained mixture was stirred for 30 minutes with a rocking mixer (RM-10 (manufactured by Seiwa Giken Co., Ltd.)) to obtain a two-component developer.
The obtained two-component developer was filled in a cyan developing device of a printer (FS-C5200DN (manufactured by Kyocera Mita Corporation)), and the toner of Example 1 was filled in a toner container for cyan toner. A sample image for image evaluation is output by a printer, and the solid image density in the sample image is measured at 10 points by an image densitometer (Spectroeye (manufactured by Gretag Macbeth)), and the average value of the 10 image densities Was the image density of the image formed with the toner of Example 1. An image density of 1.35 or more was judged as ◯, and an image density less than 1.35 was judged as ×.

<Fixability evaluation method>
Using a roller / roller type (φ26 / 25) tester (tester using a FS-C-5200DN fixing device manufactured by Kyocera Mita Co., Ltd.), a toner of 1.5 g / cm ² is placed on the paper. Fixing was performed using a tester at a nip width of 6.2 mm, a linear speed of 170 mm / second, and a fixing temperature of 150 ° C. The sheet after fixing was folded in half so that a crease was formed on the fixing portion, and rubbed 5 times on the crease with a 1 kg weight. An image peeling width of 1 mm or less at the crease after friction was judged as ◯, and over 1 mm was judged as x.

[Example 2, Reference Example 1 and Comparative Examples 1-7]
A toner was obtained in the same manner as in Example 1 except that 5 parts by mass of the wax shown in Table 3 was used instead of 5 parts by mass of wax A. Using the toners of Example 2, Reference Example 1 and Comparative Examples 1 to 7, the wax dispersion diameter, transmittance, image density, and fixability were evaluated in the same manner as in Example 1. Table 3 shows the evaluation results of the toners of Example 2, Reference Example 1 and Comparative Examples 1-7.

[Reference Example 1]
A toner was obtained in the same manner as in Example 1 except that the cylinder temperature during melt kneading was changed from 120 ° C. to 150 ° C. With respect to the obtained toner, when the wax dispersion diameter was measured in the same manner as in Example 1, the wax dispersion diameter of the toner of Reference Example 1 was 250 nm.
According to Reference Example 1, it can be seen that the dispersion diameter of the wax can be increased by increasing the temperature at the time of melt kneading when the toner is produced.

According to Example 1 , Example 2, and Reference Example 1 , the content of the first linear saturated carboxylic acid ester compound (wax 1) having 32 to 41 carbon atoms relative to the total amount of the release agent (wax) is 5 to 45% by mass, the content of the second linear saturated carboxylic acid ester compound (wax 2) having 42 to 46 carbon atoms is 20 to 70% by mass, and the third having 47 to 62 carbon atoms. It can be seen that the toner having a linear saturated carboxylic acid ester compound (wax 3) content of 15 to 45% by mass exhibits excellent fixability at low temperatures. The toners of Examples 1 and 2 and Reference Example 1 in which the wax dispersion diameter is in the range of 50 to 250 nm have a low toner transmittance of 40% or less at the bottom of the transmission spectrum at a wavelength of 400 to 500 nm. Therefore, an image having a desired image density can be formed.

  According to Comparative Examples 1 and 2, when the content of the first linear saturated carboxylic acid ester compound (wax 1) having 32 to 41 carbon atoms in the release agent is too small, an image having a desired density is obtained. Even if it can be formed, it can be seen that the fixing property of the toner at a low temperature is likely to be impaired.

  According to Comparative Example 3, when the content of the third linear saturated carboxylic acid ester compound (wax 3) having 47 to 62 carbon atoms in the release agent is excessive, an image having a desired density can be formed. It can also be seen that the fixability of the toner at low temperatures is likely to be impaired.

  According to Comparative Example 4, when the content of the third linear saturated carboxylic acid ester compound (wax 3) having 47 to 62 carbon atoms in the release agent is too small, an image having a desired density can be formed. It can also be seen that the fixability of the toner at low temperatures is likely to be impaired.

  According to Comparative Example 6, in the case of a toner in which the content of the second linear saturated carboxylic acid ester compound (wax 2) having 42 to 46 carbon atoms in the release agent is excessive, the transmission spectrum at a wavelength of 400 to 500 nm. The bottom value of the transmittance at is over 40%. For this reason, with the toner of Comparative Example 6, it is difficult to form an image with a desired density because the bottom value of the transmittance at a wavelength of 400 to 500 nm is high. At this time, the dispersion diameter of the wax exceeds 250 nm. When the dispersion diameter of the wax is large, the wax is difficult to disperse well, and other components in the binder resin are also difficult to disperse well. In such a case, components such as the charge control agent are not well dispersed in the binder resin, and the toner tends to be non-uniformly charged, making it difficult to form an image with a desired density.

  According to Comparative Example 5, when the content of the second linear saturated carboxylic acid ester compound (wax 2) having 42 to 46 carbon atoms in the release agent is too small, it is difficult to form an image having a desired density. I understand that.

(Low temperature fixability)
Further, according to Comparative Example 7, in the case where the content of the first linear saturated carboxylic acid ester compound (wax 1) having 32 to 41 carbon atoms in the release agent is excessive, the wavelength is 400 to 500 nm. The bottom value of the transmittance in the transmission spectrum exceeds 40%. For this reason, with the toner of Comparative Example 7, it is difficult to form an image with a desired density due to a high bottom value of light transmittance at a wavelength of 400 to 500 nm and non-uniform charging of the toner. At this time, the dispersion diameter of the wax exceeds 250 nm. When the dispersion diameter of the wax is large, the wax is difficult to disperse well, and other components in the binder resin are also difficult to disperse well. In such a case, components such as the charge control agent are not well dispersed in the binder resin, and the toner tends to be non-uniformly charged.

FIG. 1 is a graph showing the relationship between the wax dispersion diameter and the transmittance at the bottom of the transmission spectrum at wavelengths of 400 to 500 nm for the toners of Example 1 , Example 2, Reference Example 1 and Comparative Examples 1-7. Shown in According to FIG. 1, it can be seen that the bottom value of the light transmittance in the transmission spectrum having a wavelength of 400 to 500 nm increases as the dispersion diameter of the wax increases.

FIG. 2 is a graph showing the relationship between the wax dispersion diameter and the image density for the toners of Example 1 , Example 2, Reference Example 1 and Comparative Examples 1-7. As can be seen from FIG. 2, the image density decreases as the wax dispersion diameter increases.

Claims (1)

A toner for developing an electrostatic latent image, comprising at least a colorant and a release agent in a binder resin and having a bottom of a transmission spectrum at a wavelength of 400 to 500 nm,
The binder resin is a polyester resin,
The release agent includes a first linear saturated carboxylic acid ester compound having 32 to 41 carbon atoms, a second linear saturated carboxylic acid ester compound having 42 to 46 carbon atoms, and 47 to 62 carbon atoms. A third linear saturated carboxylic acid ester compound,
The content of the first linear saturated carboxylic acid ester compound is 5 to 45% by mass, and the content of the second linear saturated carboxylic acid ester compound is 20 to 70% by mass with respect to the total amount of the release agent. , and the Ri content of 15 to 45% by mass of the third linear saturated carboxylic acid ester compound,
The dispersion diameter of the releasing agent is Ru 50~150nm der toner for developing electrostatic latent images in the binder resin.

Images