JP5470168B2 - Toner and toner production method - Google Patents

Description

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

  The toner that visualizes the latent image is used in various image forming processes. For example, the toner is used in an electrophotographic image forming process.

  In an image forming apparatus using an electrophotographic image forming process, generally, a charging process, an exposure process, a developing process, a transfer process, a fixing process, and a cleaning process are performed to form a desired image on a recording medium. To do.

  In the charging step, the photosensitive layer on the surface of the photosensitive drum, which is a latent image carrier, is uniformly charged. In the exposure step, the electrostatic latent image is formed by projecting the signal light of the original image onto the surface of the charged photosensitive drum. In the developing step, the toner is agitated and charged, and the charged toner is supplied to the surface of the photosensitive drum to visualize the electrostatic latent image. In the transfer step, the toner image on the surface of the photosensitive drum is transferred to a recording medium such as paper or an OHP sheet. In the fixing step, the toner image is fixed on the recording medium by heating, pressing, or the like. In the cleaning step, the toner remaining on the surface of the photosensitive drum after the toner image is transferred is removed by a cleaning blade and cleaned. The transfer of the toner image to the recording medium may be performed via an intermediate transfer medium.

  The electrophotographic toner used for such image formation is produced by a polymerization method represented by, for example, a kneading and pulverizing method, a suspension polymerization method, and an emulsion polymerization aggregation method. Among these, in the kneading and pulverization method, the toner raw material, which is mainly composed of a binder resin and a colorant and is added with a release agent and a charge control agent as necessary, is melt-kneaded, cooled and solidified. The toner is produced by pulverization and classification.

  In recent years, many efforts have been made in various technical fields from the viewpoint of global environmental conservation. At present, many product materials are produced from petroleum, but energy is required and carbon dioxide is generated when these materials are produced or incinerated. Such efforts to reduce energy and carbon dioxide are very important as a countermeasure against global warming.

  As a new approach to reducing carbon dioxide as a measure against global warming, the use of plant-derived resources called biomass has attracted much attention. Carbon dioxide generated when burning biomass is originally atmospheric carbon dioxide taken in by plants by photosynthesis, so the balance of atmospheric carbon dioxide is zero. Thus, the property that does not affect the increase or decrease of carbon dioxide in the atmosphere is called carbon neutral, and the use of biomass that is carbon neutral is considered not to increase the amount of carbon dioxide in the atmosphere. Biomass materials produced from such biomass are called biomass polymers, biomass plastics, non-petroleum polymer materials, etc., and such biomass materials are made from monomers called biomass monomers. .

  In the field of electrophotography, efforts are being made to use biomass, which is an excellent resource for environmental safety and is an effective resource for suppressing an increase in carbon dioxide.

  For example, Patent Document 1 includes a polyester resin having a softening point of 80 to 120 ° C. obtained from rosin as an essential component, a polyester resin having a softening point of 160 ° C. or higher obtained from a polyvalent epoxy compound as an essential component, and carbon black. A resin composition for an electrophotographic toner is disclosed that contains a toner having both low-temperature fixability, hot offset resistance, and development durability.

JP 2008-122509 A

  However, in the toner disclosed in Patent Document 1, if the rosin content in the resin composition for electrophotographic toner is further increased in order to increase the utilization rate of biomass, the carbon black in the resin composition for electrophotographic toner is increased. Dispersion becomes uneven. The reason is that since rosin has a rigid structure, if the content is increased, the flexibility is lowered, the interaction between rosin and carbon black is lowered, and the dispersibility of carbon black is lowered. As described above, a toner with non-uniform carbon black dispersion tends to cause a decrease in charge amount and an increase in charge amount, and becomes a toner having low charge stability. Such toner cannot form a good image with high image density and no fog over a long period of time.

  Further, in the toner containing rosin as in Patent Document 1, for the purpose of increasing the image density, when the concentration of a pigment such as carbon black in the toner is increased, the distance between the carbon black particles in the toner becomes closer. The carbon black particles dispersed by stirring at the time of manufacture are easily reaggregated, and the dispersibility of the carbon black is further deteriorated. Such a phenomenon shows the same tendency not only for a toner produced by a pulverization method but also for a toner produced by a wet method such as a polymerized toner.

  An object of the present invention is to provide a toner that is excellent in charging stability even when the content of rosin is increased, and a method for producing the toner.

The toner of the present invention is a polyester resin A obtained by condensation polymerization of aromatic dicarboxylic acid, rosin, and trivalent or higher alcohol as a starting material, and the content of the rosin in the total amount of the starting material is 60% by weight. % Of a polyester resin A, a binder resin having a polyester resin B obtained by condensation polymerization of an aromatic dicarboxylic acid and a polyhydric alcohol as a starting material,
a toner containing carbon black having a pH of 2.5 or more and 6.0 or less,
The toner is characterized in that the content of unreacted rosin in the toner is 1 wt% or more and 10 wt% or less with respect to the carbon black.

The toner production method of the present invention is a polyester resin A obtained by polycondensation of aromatic dicarboxylic acid, rosin, and trivalent or higher alcohol as a starting material, and the content of the rosin in the starting material A binder resin having a polyester resin A of 60% by weight or more, an aromatic dicarboxylic acid as a starting material, and a polyester resin B obtained by polycondensation of a polyhydric alcohol, and a pH of 2.5 to 6 A mixture of carbon black of 0.0 or less and a mixture in which the content of unreacted rosin in the mixture is 1% by weight or more and 10% by weight or less based on the carbon black; ,
A melt-kneading step of melt-kneading the mixture to produce a kneaded product;
A cooling and pulverizing step in which the kneaded product is cooled and solidified and pulverized to produce a pulverized product;
And a classifying step for classifying the pulverized product.

In the toner production method of the present invention, in the mixing step,
Mixing and kneading the polyester resin A and the carbon black to prepare a master batch,
The polyester resin B and the master batch are mixed to produce the mixture.

  According to the present invention, the toner includes a binder resin and carbon black. The binder resin is a polyester resin A obtained by condensation polymerization of aromatic dicarboxylic acid, rosin, and trivalent or higher alcohol as a starting material, and the content of the rosin in the total amount of the starting material is 60% by weight. The polyester resin A as described above, and a polyester resin B obtained by condensation polymerization of an aromatic dicarboxylic acid and a polyhydric alcohol as a starting material and substantially free of rosin. Carbon black has a pH of 2.5 or more and 6.0 or less.

  As described above, in the toner having a high rosin content, the content of the unreacted rosin in the toner is 1% by weight or more and 10% by weight or less based on the carbon black, so that the carbon black is contained in the binder resin. A uniformly dispersed toner is obtained. Therefore, it is considered that the electric resistance value of each toner particle becomes uniform and the charging stability of the toner is improved, so that a good image with high image density and no fog can be stably formed over a long period of time. A toner that can be produced. In particular, when the content of carbon black in the toner is increased for the purpose of increasing the image density, the effect appears more remarkably.

  According to the invention, the toner manufacturing method includes a mixing step, a melt-kneading step, a cooling and pulverizing step, and a classification step. The mixing step is a polyester resin A obtained by condensation polymerization of aromatic dicarboxylic acid, rosin, and trivalent or higher alcohol as a starting material, and the content of the rosin in the total amount of the starting material is 60% by weight or more. A polyester resin A, a binder resin having a polyester resin B obtained by condensation polymerization of an aromatic dicarboxylic acid and a polyhydric alcohol as a starting material, and carbon having a pH of 2.5 or more and 6.0 or less A mixture in which black is mixed and the content of unreacted rosin in the mixture is 1% by weight or more and 10% by weight or less based on carbon black is prepared. In the melt-kneading step, the mixture is melt-kneaded to prepare a kneaded product. In the cooling and pulverizing step, the kneaded product is cooled and solidified, and pulverized to produce a pulverized product. In the classification step, the pulverized product is classified.

  Thus, even if the content of rosin is large, the binder resin can be obtained by preparing a toner using a mixture in which the content of unreacted rosin is 1% by weight or more and 10% by weight or less based on carbon black. Carbon black is uniformly dispersed therein, and a toner having good charging stability can be obtained.

  According to the invention, in the mixing step, the polyester resin A and carbon black are mixed and kneaded to prepare a master batch. Further, the polyester resin B and the master batch are mixed to prepare the mixture. Therefore, carbon black can be uniformly dispersed in the binder resin, and a toner having good charging stability can be obtained.

FIG. 6 is a process diagram illustrating an example of a procedure of a toner manufacturing method according to the present invention.

1. Toner The toner of the present invention contains a binder resin and a colorant, and optionally contains additives. Examples of the additive include magnetic powder, a release agent and a charge control agent.

(Binder resin)
The binder resin contains polyester resin A and polyester resin B. Polyester resin A and polyester resin B are obtained by polycondensation of an acid component such as a polybasic acid and a polyhydric alcohol as a starting material.

  Polyester resin A and polyester resin B are produced by a known condensation polymerization reaction method. As the reaction method, transesterification or direct esterification can be applied. Also, polycondensation can be promoted by increasing the reaction temperature by pressurization, or by flowing an inert gas under reduced pressure or normal pressure. In the above reaction, the reaction may be promoted using a known and commonly used reaction catalyst such as at least one metal compound among antimony, titanium, tin, zinc, aluminum, and manganese. The addition amount of these reaction catalysts is preferably 0.01 parts by weight or more and 1.0 parts by weight or less with respect to 100 parts by weight of the total amount of the acid component and the polyhydric alcohol.

  In the production of the polyester resin A, aromatic dicarboxylic acid and rosin are used as the acid component of the starting material, and trivalent or higher alcohol is used as the polyhydric alcohol of the starting material. A polyol structure having an appropriate branch is formed by the reaction of the aromatic dicarboxylic acid and the trivalent or higher alcohol. Since the polyester resin contains an appropriate branched structure, the low-temperature fixability of the toner can be maintained without extremely increasing the softening temperature of the resin, and the molecular weight distribution of the resin can be widened. Since a large resin can be obtained, the offset resistance of the toner is improved.

  Examples of the aromatic dicarboxylic acid used for the polyester resin A include phthalic acid, terephthalic acid, isophthalic acid, biphenyldicarboxylic acid, naphthalenedicarboxylic acid, 5-tert-butyl-1,3-benzenedicarboxylic acid and the like. Further, as the acid component of the polyester resin A, an aromatic dicarboxylic acid derivative such as an aromatic dicarboxylic acid anhydride or a lower alkyl ester may be used instead of the aromatic dicarboxylic acid. Of the above aromatic dicarboxylic acid compounds, it is preferable to use at least one of terephthalic acid, isophthalic acid, and lower alkyl esters thereof.

  Terephthalic acid and isophthalic acid have a high electron resonance stabilization effect due to the aromatic ring skeleton, and are excellent in charging stability and can provide a resin having an appropriate strength. Examples of lower alkyl esters of terephthalic acid and isophthalic acid include dimethyl terephthalate, dimethyl isophthalate, diethyl terephthalate, diethyl isophthalate, dibutyl terephthalate, and dibutyl isophthalate. Of these, dimethyl terephthalate or dimethyl isophthalate is preferably used from the viewpoint of cost and handling.

  These aromatic dicarboxylic acid compounds can be used individually by 1 type, or can use 2 or more types together.

  Examples of the trivalent or higher alcohol used in the polyester resin A include trimethylolethane, trimethylolpropane, glycerin, pentaerythritol, and the like, and at least one of these polyhydric alcohols can be used. Among these, glycerin is more preferable because a technique for producing from plant-derived raw materials has been established industrially, is easily available, and an effect of promoting utilization of biomass is obtained.

  In the polyester resin A, the molar ratio of the trivalent or higher alcohol to the aromatic dicarboxylic acid compound is preferably 1.05 or more and 1.65 or less. When the molar ratio of the trihydric or higher alcohol to the aromatic dicarboxylic acid compound is less than 1.05, the molecular weight distribution on the high molecular weight side of the resin is broadened, and the low melting point fixing property of the toner is lowered due to the high melting point. As a result, it becomes impossible to control the spread of the molecular weight distribution, resulting in gelation of the toner. When the molar ratio exceeds 1.65, the polyester resin contains few branched structures, so that the softening temperature and the glass transition temperature are lowered, and as a result, the storage stability of the toner is lowered.

  The rosin used for the production of the polyester resin A is a natural resin obtained from pine. Rosin is mainly composed of resin acids such as abietic acid, parastrinic acid, neoabietic acid, pimaric acid, dehydroabietic acid, isopimaric acid, sandaracopimalic acid and dihydroabietic acid, and mixtures thereof.

  Abietic acid, parastrinic acid, and neoabietic acid are rosin isomers with conjugated double bonds. Pimaric acid, dehydroabietic acid and isopimaric acid are rosin isomers that do not have a conjugated double bond.

  Rosin is classified into tall rosin obtained from crude tall oil which is a by-product in the pulp manufacturing process, gum rosin obtained from raw pine ani, wood rosin obtained from pine stumps, and the like. These rosins are obtained by a conventionally known production method.

  The content of unreacted rosin in the polyester resin A is preferably 0.4% by weight or more and 3.0% by weight or less.

  As the rosin, disproportionated rosin is preferable. Disproportionated rosin is a rosin that has been stabilized by a disproportionation reaction, and is obtained by heating rosin at a high temperature in the presence of a noble metal catalyst or a halogen catalyst, resulting in unstable intramolecular conjugated double bonds. It is a lost polycondensed cyclic monocarboxylic acid, and is characterized by being less susceptible to alteration than rosin having a conjugated double bond.

  The main component of disproportionated rosin is a mixture of dehydroabietic acid and dihydroabietic acid. Since the disproportionated rosin contains a bulky and rigid skeleton of the hydrophenanthrene ring, the introduction of the disproportionated rosin as a component of the polyester results in a glass transition than when rosins other than the disproportionated rosin are used. A temperature drop can be suppressed and a toner having good storage stability can be obtained.

  As described above, the polyester resin A contains aromatic dicarboxylic acid, rosin, and trivalent or higher alcohol as starting materials. In the present invention, in order to obtain a toner excellent in environmental safety, the content of the rosin in the total amount of the starting material is set to 60% by weight or more as a precondition of the polyester resin A.

  In addition to the above aromatic dicarboxylic acid compound and rosin, the polyester resin A can further use an aliphatic polycarboxylic acid or a trivalent or higher valent aromatic polycarboxylic acid as an acid component.

  Examples of the aliphatic polycarboxylic acid include alkyl dicarboxylic acids such as succinic acid, adipic acid, sebacic acid and azelaic acid, succinic acid substituted with an alkyl group having 16 to 18 carbon atoms, fumaric acid, maleic acid, citraconic acid, and itaconic acid. Examples thereof include unsaturated dicarboxylic acids such as acid and glutaconic acid, and dimer acid.

  The content of the aliphatic polycarboxylic acid in the polyester resin A is preferably 0.5 mol or more and 15 mol or less, more preferably 1 mol or more and 13 mol or less with respect to 100 mol of the aromatic dicarboxylic acid compound. preferable. When the content of the aliphatic polycarboxylic acid in the polyester resin A is in the above range, the low-temperature fixability of the toner is improved.

  Examples of the trivalent or higher valent aromatic polycarboxylic acid include trimellitic acid, pyromellitic acid, naphthalenetricarboxylic acid, benzophenonetetracarboxylic acid, biphenyltetracarboxylic acid, and anhydrides thereof. These aromatic polycarboxylic acids can be used individually by 1 type, or may use 2 or more types together. Of these aromatic polycarboxylic acids, trimellitic anhydride is preferably used from the viewpoint of reactivity.

  The content of the trivalent or higher aromatic polycarboxylic acid in the polyester resin A is preferably 0.1 mol or more and 5 mol or less, and 0.5 mol or more and 3 mol or less with respect to 100 mol of the aromatic dicarboxylic acid compound. The following is more preferable. If the content of the trivalent or higher valent aromatic polycarboxylic acid in the polyester resin A is less than 0.1 mol, the branched structure of the polyester resin A is not sufficient, and a polyester resin A having a broad distribution on the high molecular weight side is obtained. Therefore, the offset resistance of the toner may be reduced. On the other hand, if it exceeds 5 moles, the softening temperature of the polyester resin A becomes too high and the low-temperature fixability of the toner may be lowered.

  Polyester resin A can further use at least one of an aliphatic diol and an etherified diphenol as a polyhydric alcohol, in addition to trihydric or higher alcohols.

  Examples of the aliphatic diol include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3- Butanediol, 1,4-butenediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, neopentyl glycol, 2-ethyl-2-methylpropane-1,3-diol, 2-butyl-2- Ethylpropane-1,3-diol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2,4-dimethyl-1,5-pentanediol, 2, 2,4-trimethyl-1,3-pentanediol, 1,7-heptanediol, 1,8-octanediol, 1,9 -Nonanediol, 1,10-decanediol, 3-hydroxy-2,2-dimethylpropyl-3-hydroxy-2,2-dimethylpropanoate, diethylene glycol, triethylene glycol, dipropylene glycol and the like. Of these aliphatic diols, ethylene glycol, 1,3-propanediol, or neopentyl glycol is preferably used from the viewpoint of reactivity with acids and the glass transition temperature of the resin. These aliphatic diols can be used alone or in combination of two or more.

  The content of the aliphatic diol in the polyester resin A is preferably 5 mol or more and 20 mol or less with respect to 100 mol of the aromatic dicarboxylic acid compound.

  Etherified diphenol is a diol obtained by addition reaction of bisphenol A and alkylene oxide. Examples of the alkylene oxide include ethylene oxide and propylene oxide, and the alkylene oxide is preferably added so that the average added mole number is 2 mol or more and 16 mol or less with respect to 1 mol of bisphenol A.

  The content of the etherified diphenol in the polyester resin A is preferably 5 mol or more and 35 mol or less with respect to 100 mol of the aromatic dicarboxylic acid compound.

  The content of the polyester resin A is preferably 20 parts by weight or more and 60 parts by weight or less with respect to 100 parts by weight of the toner. When the content of the polyester resin A is less than 20 parts by weight, the viscosity of the toner increases and the low-temperature fixability of the toner is impaired. On the other hand, when the content of the polyester resin A exceeds 60 parts by weight, the content of rosin is increased, so that the mechanical strength of the toner and the powder fluidity are decreased.

  The polyester resin B is a polyester resin substantially free of rosin and preferably has a high molecular weight and a high viscosity in order to impart high temperature offset resistance to the toner.

  As an acid component of the polyester resin B, the same aromatic dicarboxylic acid compound as that of the polyester resin A can be used. The aromatic dicarboxylic acid compound contained in the polyester resin A and the polyester resin B may be the same or different. Polyester resin B can further use an aliphatic polycarboxylic acid similar to polyester resin A or a trivalent or higher valent aromatic polycarboxylic acid in addition to the aromatic dicarboxylic acid compound as an acid component. These acid components may be the same or different in polyester resins A and B.

  Further, as the acid component of the polyester resin B, polybasic acids such as saturated polybasic acids and unsaturated polybasic acids, acid anhydrides thereof, and lower alkyl esters thereof can be used.

  Saturated polybasic acids, saturated polybasic acids, and lower alkyl esters of saturated polybasic acids include, for example, adipic acid, sebacic acid, orthophthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, succinic acid, succinic anhydride, Dibasic acids such as alkyl succinic acid having 8 to 18 carbon atoms, alkyl succinic anhydride, alkenyl succinic acid, alkenyl succinic anhydride; trimellitic acid, trimellitic anhydride, cyanuric acid, pyromellitic acid, pyromellitic anhydride Etc.

  Examples of the unsaturated polybasic acid include maleic acid, maleic anhydride, fumaric acid and the like.

  A saturated polybasic acid and an unsaturated polybasic acid can be used individually by 1 type, or may use 2 or more types together. Moreover, you may use monobasic acids, such as benzoic acid and p-tert- butyl benzoic acid, as needed.

  As the polyhydric alcohol of the polyester resin B, trivalent or higher alcohols, aliphatic diols and etherified diphenols can be used in the same manner as the polyester resin A, and the same one as the polyester resin A may be used. Different ones may be used. In addition, alicyclic diols such as cyclohexanedimethanol may be used. A polyhydric alcohol may be used independently and may use 2 or more types together. Furthermore, you may use monoalcohols, such as a stearyl alcohol, in the range which does not impair the effect of this invention as needed.

The viscosity of the polyester resin B is 10 ³ Pa · s or more and 10 ⁵ Pa · s or less at the softening temperature of the polyester resin A. When the viscosity of the polyester resin B at the softening temperature of the polyester resin A is less than 10 ³ Pa · s, the hot offset resistance of the toner cannot be obtained. Moreover, when the viscosity B of the polyester resin B at the softening temperature of the polyester resin A exceeds 10 ⁵ Pa · s, the difference in melt viscosity between the polyester resin A and the polyester resin B during kneading is large, and the resin mixing property becomes poor. Further, the dispersibility of the polyester resin A and the polyester resin B in the toner becomes non-uniform. A portion where the ratio of the polyester resin A is high in the toner particles is easily broken, and fine powder having a small particle diameter is generated by the breakage. Such fine powder widens the particle size distribution and the charge distribution, resulting in problems such as image fogging.

  The glass transition temperatures of the polyester resin A and the polyester resin B are not particularly limited, and can be appropriately selected from a wide range. It is more preferable that the temperature is not lower than 65 ° C and not higher than 65 ° C. When the glass transition temperatures of the polyester resin A and the polyester resin B are less than 45 ° C., the storage stability of the toner becomes insufficient, so that the toner is likely to thermally aggregate inside the image forming apparatus, resulting in development failure. In addition, the temperature at which hot offset begins to occur (hereinafter referred to as “hot offset start temperature”) decreases.

  “Hot offset” means that when a toner is heated and pressed by a fixing member and fixed on a recording medium, the cohesive force of the heated toner particles is less than the adhesive force between the toner and the fixing member, so that the toner layer This is a phenomenon in which the toner is divided and a part of the toner adheres to the fixing member and is removed. On the other hand, when the glass transition temperatures of the polyester resins A and B exceed 80 ° C., the low-temperature fixability of the toner is lowered and fixing failure occurs.

  The softening temperature of the polyester resin A is preferably 100 ° C. or higher and 130 ° C. or lower. The softening temperature of the polyester resin B is higher than the softening temperature of the polyester resin A, and is preferably 120 ° C. or higher and 170 ° C. or lower. In addition, it is preferable that the softening temperature of the polyester resin B is higher than the softening temperature of the polyester resin A in the range of 20 ° C. or more and 50 ° C. or less.

  The weight average molecular weight of the polyester resin A is preferably 2500 or more and 7000 or less. The weight average molecular weight of the polyester resin B is preferably 15000 or more and 50000 or less.

  The number average molecular weight of the polyester resin A is preferably 1000 or more and 2500 or less. The number average molecular weight of the polyester resin B is preferably 2000 or more and 5000 or less.

  The molecular weight distribution index of the polyester resin A is preferably 1.5 or more and 5.0 or less. The molecular weight distribution index of the polyester resin B is preferably 7.0 or more and 12.0 or less.

  The acid value of the polyester resin A and the polyester resin B is preferably 5 mgKOH / g or more and 30 mgKOH / g or less.

The THF insoluble content of the polyester resin B is preferably 15% or more and 45% or less.
As long as the object of the present invention can be achieved, the binder resin includes a polystyrene polymer, a polystyrene copolymer such as a styrene-acrylic resin, a polyester resin other than the polyester resin, and the like. A resin used as a landing resin may be used together with the polyester resin.

(Coloring agent)
In this embodiment, carbon black is used as a colorant.

  Examples of carbon black include channel black, roller black, disk black, gas furnace black, oil furnace black, thermal black, and acetylene black.

  Carbon black can be used individually by 1 type, and can use 2 or more types together. Moreover, it can be used in combination with a color-based colorant or dye as appropriate for hue adjustment.

  The pH of carbon black is 2.5 or more and 6.0 or less. When the pH of the carbon black is 2.5 or more and 6.0 or less, the charging stability of the toner can be improved.

  If the pH of the carbon black is less than 2.5, the resulting toner has a high hygroscopic property, and the chargeability is lowered to cause fogging. When the pH of the carbon black exceeds 6.0, the dispersibility of the carbon black is lowered and the charge distribution is widened, so that fog occurs.

  The concentration of carbon black in the toner is preferably 5% by weight to 12% by weight, and more preferably 7% by weight to 10% by weight. When using the master batch described later at the time of preparation of the toner of the present invention, it is preferable to adjust the usage amount of the master batch so that the concentration of carbon black in the toner falls within the above range. When the concentration of carbon black is within the above range, it is possible to obtain a toner having a high coloring power while suppressing the filler effect due to the addition of carbon black, and sufficient image density even if the amount of toner consumption is small. Therefore, it is possible to form a good image having high color developability and excellent image quality.

(Magnetic powder)
Examples of the magnetic powder include magnetite, γ-hematite, and various ferrites.

(Release agent)
As the release agent, those commonly used in this field can be used, and examples thereof include wax. As the wax, paraffin wax. Natural waxes such as carnauba wax and rice wax, synthetic waxes such as polypropylene wax, polyethylene wax, and Fischer-Tropsch wax, petroleum waxes such as coal waxes such as montan wax, alcohol waxes, and ester waxes. Can be mentioned.

  A mold release agent may be used individually by 1 type, and may use 2 or more types together. The addition amount of the release agent is not particularly limited, and is appropriately selected from a wide range according to various conditions such as the type and content of other components such as a binder resin and a colorant and the characteristics required for the toner to be produced. Although it can be selected, it is preferably 3 parts by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the binder resin. When the addition amount of the release agent is less than 3 parts by weight, the low-temperature fixability and the hot offset resistance are not sufficiently improved. When the addition amount of the release agent exceeds 10 parts by weight, the dispersibility of the release agent in the kneaded product is lowered, and a toner having a certain performance cannot be obtained stably. In addition, a phenomenon called filming occurs in which the toner is fused in the form of a film (film) on the surface of an image carrier such as a photoreceptor.

  The melting point (Tm) of the release agent is preferably 50 ° C. or higher and 180 ° C. or lower. When the melting point is less than 50 ° C., the release agent melts in the developing device, the toner particles aggregate, and filming on the surface of the photoreceptor occurs. When the melting point exceeds 180 ° C., the release agent cannot be sufficiently eluted when the toner is fixed on the recording medium, and the hot offset resistance is not sufficiently improved.

(Charge control agent)
As the charge control agent, a charge control agent for positive charge control and negative charge control commonly used in this field can be used.

  Examples of charge control agents for positive charge control include nigrosine dyes, basic dyes, quaternary ammonium salts, quaternary phosphonium salts, aminopyrines, pyrimidine compounds, polynuclear polyamino compounds, aminosilanes, nigrosine dyes and derivatives thereof, triphenylmethane Derivatives, guanidine salts, amidine salts and the like can be mentioned.

  The charge control agents for controlling negative charges include chromium azo complex dyes, iron azo complex dyes, cobalt azo complex dyes, chromium complexes of salicylic acid and salicylic acid derivatives, zinc complexes, aluminum complexes and boron complexes, salicylate compounds, naphtholic acid and naphtholic acid. Chromium complexes of derivatives, zinc complexes, aluminum complexes and boron complexes, naphtholate compounds, chromium complexes of benzylic acid and benzylic acid derivatives, zinc complexes, aluminum complexes and boron complexes, benzylate compounds, long chain alkyl carboxylates, Mention may be made of surfactants such as long-chain alkyl sulfonates.

  The addition amount of the charge control agent is preferably 0.01 parts by weight or more and 5 parts by weight or less with respect to 100 parts by weight of the binder resin.

  The toner of the present invention contains 1 to 10% by weight of unreacted rosin with respect to carbon black. As described above, rosin is used as the starting material of the polyester resin A, and the content of the rosin is large (60% by weight or more based on the total amount of the starting material of the polyester resin A), but the unreacted rosin is converted into carbon black. On the other hand, by including 1 wt% or more and 10 wt% or less, a toner in which carbon black is uniformly dispersed in the binder resin can be obtained. This is presumably because the unreacted rosin acts as a dispersant for dispersing the carbon black in the binder resin. A toner in which carbon black is uniformly dispersed in a binder resin is considered to have a uniform electric resistance value of individual toner particles and a good charge stability of the toner. A good image without fog can be formed stably.

  If the content of the unreacted rosin in the toner is less than 1% by weight with respect to the carbon black, the carbon black cannot be uniformly dispersed in the binder resin, and the charging stability of the toner is lowered. When the content of the unreacted rosin in the toner exceeds 10% by weight with respect to the carbon black, the hot offset resistance decreases. In addition, the charging stability of the toner decreases.

  The content of unreacted rosin in the toner is more preferably 2% by weight or more and 10% by weight or less, and further preferably 3.5% by weight or more and 6% by weight or less with respect to the carbon black.

  The content of unreacted rosin in the toner can be adjusted by, for example, a method for producing polyester resin A. Specifically, the content of unreacted volatile rosin can be adjusted by adjusting the reaction conditions (reaction temperature, reaction time, etc.) of the condensation polymerization of polyester resin A.

2. Toner Manufacturing Method FIG. 1 is a process diagram showing an example of the procedure of a toner manufacturing method of the present invention. The toner manufacturing method according to the present invention is a dry particle forming method, and includes a mixing step S1, a melt-kneading step S2, a cooling and pulverizing step S3, a classification step S4, and an external addition step S5.

(1) Mixing step S1
In the mixing step S1, the binder resin and carbon black are dry mixed by a mixer to produce a mixture. At this time, additives are added as necessary.

  In order to uniformly disperse the carbon black in the polyester resin, the carbon black is preferably used as a master batch. The master batch can be produced, for example, by dry-mixing the polyester resin A and carbon black with a mixer and kneading the resulting powder mixture with a kneader. The kneading temperature depends on the softening temperature of the polyester resin A, but is usually about 50 to 150 ° C, preferably about 50 to 120 ° C.

  Known mixers can be used. For example, Henschel mixer (trade name, manufactured by Mitsui Mining Co., Ltd.), super mixer (trade name, manufactured by Kawata Co., Ltd.), Mechano Mill (trade name, manufactured by Okada Seiko Co., Ltd.) Henschel type mixing devices such as HONSHELL type mixing equipment, Ongmill (trade name, manufactured by Hosokawa Micron Corporation), Hybridization system (trade name, manufactured by Nara Machinery Co., Ltd.), Cosmo System (trade name, manufactured by Kawasaki Heavy Industries, Ltd.), etc. . As the kneading machine, a known kneading machine can be used. For example, a general kneading machine such as a kneader, a twin-screw extruder, a two-roll mill, a three-roll mill, or a lab blast mill can be used. More specifically, for example, TEM-100B (trade name, manufactured by Toshiba Machine Co., Ltd.), PCM-65 / 87, PCM-30 (all of which are trade names, manufactured by Ikegai Co., Ltd.), etc. Extruder, Needex (trade name, manufactured by Mitsui Mining Co., Ltd.) and other open roll type kneaders. The melt kneading may be performed using a plurality of kneaders.

  The obtained master batch is used after being pulverized to a particle diameter of about 2 mm to 3 mm, for example.

(2) Melt-kneading step S2
In the melt-kneading step S2, the mixture produced in the mixing step is melt-kneaded by a kneader to produce a melt-kneaded product in which carbon black and additives added as necessary are dispersed in the binder resin. .

  As a kneader used in the melt-kneading step, a known one can be used, and the same one as the above-mentioned kneader used for preparing a masterbatch can be used. Melt kneading may be performed using a plurality of kneaders.

  The temperature at the time of melt kneading depends on the kneader to be used, but is preferably a temperature not higher than the boiling point of the unreacted rosin, and preferably not lower than 80 ° C. and not higher than 200 ° C. By performing melt-kneading at a temperature in such a range, carbon black and additives added as necessary can be uniformly dispersed in the binder resin. Moreover, it can suppress that unreacted rosin evaporates by melt-kneading and content of the unreacted rosin contained in a mixture reduces.

(3) Cooling and grinding step S3
In the cooling and pulverizing step S3, the melt-kneaded product obtained in the melt-kneading step is cooled and solidified and pulverized to obtain a pulverized product.

  The cooled and solidified melt-kneaded product is coarsely pulverized into a coarsely pulverized product having a volume average particle size of 100 μm or more and 5 mm or less by a hammer mill or a cutting mill. Further pulverized to the following. For finely pulverizing the coarsely pulverized product, for example, a jet pulverizer using a supersonic jet stream, or a coarsely pulverized product in a space formed between a rotor (rotor) rotating at high speed and a stator (liner) An impact type pulverizer that introduces and pulverizes can be used.

(4) Classification process S4
In the classification step S4, the pulverized product obtained in the cooling and pulverization step S3 is classified by a classifier to remove excessively pulverized toner particles and coarse toner particles, thereby obtaining an unexternally added toner. The excessively pulverized toner particles and coarse toner particles can be collected and reused for the production of other toners.

  For the classification, a known classifier capable of removing excessively pulverized toner particles by classification using centrifugal force and wind force can be used. For example, a swirl type wind classifier (rotary wind classifier) or the like can be used.

  The volume average particle diameter of the non-externally added toner obtained after classification is preferably 3 μm or more and 15 μm or less. In order to obtain a high-quality image, the volume average particle size of the non-externally added toner is preferably 3 μm or more and 9 μm or less, and more preferably 5 μm or more and 8 μm or less. When the volume average particle size of the non-externally added toner is less than 3 μm, the toner has a small particle size, so that high charging and low fluidization occur. Due to the high charging and low fluidization of the toner, the toner is not stably supplied to the photoreceptor, and background fogging and a decrease in image density occur. When the volume average particle size of the non-externally added toner exceeds 15 μm, the particle size of the toner is large and a high-definition image cannot be obtained. In addition, as the particle size increases, the specific surface area of the toner decreases and the charge amount of the toner decreases. As a result, the toner is not stably supplied to the photoreceptor, and internal contamination due to toner scattering occurs.

(5) External addition process S5
In the external addition step S5, the toner is obtained by mixing the non-external addition toner obtained in the classification step S4 and the external additive. By adding the external additive, the fluidity of the toner and the cleaning property of the residual toner on the surface of the photoreceptor are improved, and filming on the photoreceptor can be prevented. Non-externally added toner to which no external additive is added can also be used as the toner.

  External additives include inorganic oxides such as silica, alumina, titania, zirconia, tin oxide, and zinc oxide, compounds such as acrylates, methacrylates, and styrene, or copolymer resins of these compounds Examples thereof include fine particles, fluororesin fine particles, silicone resin fine particles, and higher fatty acids such as stearic acid, or metal salts of these higher fatty acids, carbon black, graphite fluoride, silicon carbide, boron nitride, and the like.

  The external additive is preferably surface-treated with a silicone resin, a silane coupling agent or the like. The amount of the external additive added is preferably 0.5 parts by weight or more and 5 parts by weight or less with respect to 100 parts by weight of the binder resin.

  The number average particle size of primary particles of the external additive is preferably 10 nm or more and 500 nm or less. When the number average particle diameter of the primary particles of the external additive is within such a range, the fluidity of the toner is further improved.

The BET specific surface area of the external additive is preferably 20 m ² / g or more and 200 m ² / g or less. When the BET specific surface area of the external additive is in such a range, appropriate fluidity and chargeability can be imparted to the toner.

3. Developer The toner of the present invention can be used as a one-component developer composed only of toner, or can be mixed with a carrier and used as a two-component developer.

  As the carrier, a known carrier can be used. For example, a resin-coated carrier or a resin in which iron or copper, zinc, nickel, cobalt, manganese, chromium or the like alone or a composite ferrite and carrier core particles are coated with a coating material. And a resin-dispersed carrier in which magnetic particles are dispersed.

  Known coating materials can be used, such as polytetrafluoroethylene, monochlorotrifluoroethylene polymer, polyvinylidene fluoride, silicone resin, polyester resin, metal compound of ditertiary butylsalicylic acid, styrene resin, acrylic resin , Polyamide, polyvinyl butyral, nigrosine, amino acrylate resin, basic dye, basic dye lake, silica fine powder, alumina fine powder, and the like.

  The resin used for the resin-dispersed carrier is not particularly limited, and examples thereof include styrene acrylic resin, polyester resin, fluorine resin, and phenol resin. Either of them is preferably selected according to the toner component, and one kind can be used alone, or two or more kinds can be used in combination.

  The shape of the carrier is preferably a spherical shape or a flat shape. The particle diameter of the carrier is not particularly limited, but is preferably 10 to 100 μm, more preferably 20 μm to 50 μm, considering high image quality. Since the carrier particle diameter is 50 μm or less, the contact opportunity between the toner and the carrier is increased, the charge of each toner particle can be appropriately controlled, no non-image area fog occurs, and a high-quality image is formed. Can do.

Furthermore, the volume resistivity of the carrier is preferably 10 ⁸ Ω · cm or more, more preferably 10 ¹² Ω · cm or more. The volume resistivity of the carrier is determined by placing carrier particles in a container having a cross-sectional area of 0.50 cm ² and tapping, then applying a load of 1 kg / cm ² to the particles packed in the container and placing the load between the load and the bottom electrode. It is a value obtained from a current value when a voltage generating an electric field of 1000 V / cm is applied. When the resistivity is low, the carrier is charged when a bias voltage is applied to the developing sleeve, and the carrier particles easily adhere to the photoreceptor. Further, breakdown of the bias voltage is likely to occur.

  The magnetization strength (maximum magnetization) of the carrier is preferably 10 to 60 emu / g, more preferably 15 to 40 emu / g. Under a general developing roller magnetic flux density condition, if it is less than 10 emu / g, the magnetic binding force does not work, which causes carrier scattering. On the other hand, if the magnetization strength exceeds 60 emu / g, the carrier spikes become too high in the non-contact development, and it becomes difficult to maintain the non-contact state between the image carrier and the toner. Further, in the contact development, a sweep is likely to appear in the toner image.

  The use ratio of the toner and the carrier in the two-component developer is not particularly limited, and can be appropriately selected according to the kind of the toner and the carrier. Further, the coverage of the carrier with the toner is preferably 40% or more and 80% or less.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.
Each physical property value in Examples and Comparative Examples was measured as follows.

  In the examples described below, in the production of the polyester resin A, a part of the rosin is not subjected to the condensation polymerization with the acid component and the alcohol component, and when the condensation polymerization is completed, a part of the rosin is removed. This is a procedure for more accurately adjusting the amount of unreacted rosin. By increasing the amount of rosin added when the condensation polymerization is completed, the content of unreacted rosin in the toner can be increased. The method for producing the toner of the present invention is not limited to the procedure of such an embodiment, and the amount of unreacted rosin is determined according to the reaction conditions (reaction temperature, reaction time) during the condensation polymerization of the polyester resin A as described above. It can be controlled by adjusting time).

[Glass transition temperature (Tg) of polyester resin]
Using a differential scanning calorimeter (trade name: Diamond DSC, manufactured by PerkinElmer Japan Co., Ltd.), a sample 0.01 g was heated at a heating rate of 10 ° C./minute (10 ° C./minute) in accordance with Japanese Industrial Standard (JIS) K7121-1987. ) And the DSC curve was measured. The straight line obtained by extending the base line on the low temperature side of the endothermic peak corresponding to the glass transition of the obtained DSC curve to the high temperature side and the tangent line drawn at the point where the gradient is maximum with respect to the low temperature side curve of the endothermic peak The temperature at the intersection was taken as the glass transition temperature (Tg).

[Softening temperature of polyester resin (Tm)]
Using a flow characteristic evaluation apparatus (trade name: Flow Tester CFT-500C, manufactured by Shimadzu Corporation), 1 g of a sample was heated at a heating rate of 6 ° C. per minute, and a load of 10 kgf / cm ² (9.8 × 10 ⁵ Pa). And the temperature at which half of the sample flowed out from the die (nozzle diameter 1 mm, length 1 mm) was determined, and was defined as the softening temperature (Tm).

[Weight average molecular weight (Mw) and number average molecular weight (Mn) of polyester resin]
The sample was dissolved in tetrahydrofuran (THF) so as to be 0.25 wt%, and 200 μL of the sample was injected into a GPC apparatus (trade name: HLC-8220 GPC, manufactured by Tosoh Corporation), and a molecular weight distribution curve was obtained at a temperature of 40 ° C. .

  From the obtained molecular weight distribution curve, the weight average molecular weight Mw and the number average molecular weight Mn are obtained, and the molecular weight distribution index (Mw / Mn; hereinafter simply referred to as “Mw / Mn”) which is the ratio of the weight average molecular weight Mw to the number average molecular weight Mn. Stipulated). The molecular weight calibration curve was prepared using standard polystyrene.

[Acid value of polyester resin and rosin]
It measured by the neutralization titration method. 5 g of a sample was dissolved in 50 mL of tetrahydrofuran (THF), and several drops of an ethanol solution of phenolphthalein was added as an indicator, followed by titration with a 0.1 mol / L potassium hydroxide (KOH) aqueous solution. The point at which the color of the sample solution changed from colorless to purple was used as the end point, and the acid value (mgKOH / g) was calculated from the amount of potassium hydroxide aqueous solution required to reach the end point and the weight of the sample subjected to titration. .

[THF insoluble matter of polyester resin]
1 g of the sample was put into a cylindrical filter paper and applied to a Soxhlet extractor. Using 100 mL of tetrahydrofuran (THF) as an extraction solvent, the mixture was heated to reflux for 6 hours to extract a THF soluble fraction from the sample. After removing the solvent from the extract containing the THF soluble fraction, the THF soluble fraction was dried at 100 ° C. for 24 hours, and the obtained THF soluble fraction was weighed to determine the weight X (g). . From the THF-soluble fraction weight X (g) and the weight of the sample used for the measurement (1 g), the ratio P (wt%) of the THF-insoluble fraction in the sample is calculated based on the following formula (1). did. Hereinafter, this ratio P is referred to as THF insoluble matter.
P (% by weight) = {1 (g) −X (g)} / 1 (g) × 100 (1)

[Melting point of release agent]
Using a differential scanning calorimeter (trade name: Diamond DSC, manufactured by PerkinElmer Japan Co., Ltd.), 0.01 g of a sample was heated from a temperature of 20 ° C. to 200 ° C. at a heating rate of 10 ° C. per minute, and then from 200 ° C. to 20 ° C. The DSC curve was measured by repeating the rapid cooling operation twice. The temperature of the endothermic peak corresponding to the melting of the DSC curve measured in the second operation was taken as the melting point of the release agent.

[Volume average particle diameter and coefficient of variation of toner]
To 50 ml of electrolyte (trade name: ISOTON-II, manufactured by Beckman Coulter, Inc.), 20 mg of a sample and 1 ml of sodium alkyl ether sulfate (dispersant, manufactured by Kishida Chemical Co., Ltd.) are added, and an ultrasonic disperser (trade name: UH). -50, manufactured by SMT Co., Ltd.) for 3 minutes at a frequency of 20 kHz to obtain a measurement sample.

This sample for measurement was measured using a particle size distribution measuring device (trade name: Multisizer 3, manufactured by Beckman Coulter, Inc.) under the conditions of an aperture diameter of 20 μm and the number of measured particles of 50000 counts. The average particle size was determined. Further, the coefficient of variation of the toner was calculated from the following formula (2) based on the volume average particle diameter and its standard deviation.
Coefficient of variation CV (%) = (standard deviation in volume particle size distribution / volume average particle size) × 100
... (2)

[Content of unreacted rosin]
Gas chromatograph Agilent-6890 was used, the inlet and detector temperatures were set to 300 ° C., the vaporization chamber temperature was set to 60 ° C., and the temperature raising program was raised to 350 ° C. at 10 ° C./min after 60 ° C./2 min. Under these conditions, the content of unreacted rosin in the polyester resin and toner was determined from the obtained gas chromatogram.

[Preparation of polyester resin A1]
In a reaction vessel equipped with a stirrer, a heating device, a thermometer, a condenser, a fractionator, and a nitrogen introduction tube, 335 g of isophthalic acid and disproportionated rosin (acid value 157.2 mgKOH / g) as acid components 1530 g, 280 g of glycerol as an alcohol component, and 1.72 g of tetra-n-butyl titanate as a reaction catalyst (corresponding to 0.080 parts by weight with respect to 100 parts by weight of the total amount of the acid component and the alcohol component) were added. These raw materials are stirred in a nitrogen atmosphere, and the condensation polymerization reaction is carried out at 250 ° C. for 10 hours while distilling off the generated water. After confirming that the predetermined softening temperature has been reached by a flow tester, the reaction is completed. Polyester resin A1 (glass transition temperature 55 ° C., softening temperature 111 ° C., weight average molecular weight 2520, Mw / Mn = 1.9, acid value 11 mg KOH / g, unreacted rosin 0.27% by weight, THF insoluble content 0% )

[Preparation of polyester resin A2]
A polyester resin A2 was obtained in the same manner as in the production method of the polyester resin A1, except that 5 g of a disproportionated rosin was not subjected to polycondensation with the acid component and alcohol component and added after polycondensation. . The rosin added after the condensation polymerization reacts somewhat while the temperature of the polyester resin A2 is lowered, but it is considered that the rosin is mostly in the monomer state.

[Preparation of polyester resins A3 to A8]
Except that the amount of disproportionated rosin to be polycondensed with the acid component and the alcohol component and the amount of disproportionated rosin to be added after the polycondensation were changed to the values shown in Table 1, the same as the production method of polyester resin A2. Thus, polyester resins A3 to A8 were obtained.

[Preparation of polyester resin A9]
As an acid component, 305 g of terephthalic acid and 30 g of trimellitic anhydride were used, the addition amount of isophthalic acid was changed to 55 g, the addition amount of disproportionated rosin was changed to 1390 g, and the addition amount of glycerin was changed to 300 g. Further, 150 g of 1,3-propanediol was used as the alcohol component, the amount of disproportionated rosin to be polycondensed with the acid component and the alcohol component was changed to 1370 g, and the disproportionated rosin added after the polycondensation was added. A polyester resin A9 was obtained in the same manner as in the production method of the polyester resin A2, except that the amount was changed to 20 g.

[Preparation of polyester resin B]
In a reaction vessel equipped with a stirrer, a heating device, a thermometer, a cooling tube, a fractionation device, and a nitrogen introduction tube, 350 g of terephthalic acid, 400 g of isophthalic acid, and 50 g of trimellitic anhydride as an alcohol component as an alcohol component 125 g of glycerin, 350 g of PO2 mol adduct of bisphenol A, 450 g of PO3 mol adduct of bisphenol A, and 1.38 g of tetra-n-butyl titanate were added as reaction catalysts. These raw materials are stirred under a nitrogen atmosphere, and the condensation polymerization reaction is carried out at 220 ° C. for 10 hours while distilling off the generated water, and then reacted under a reduced pressure of 5 to 20 mmHg. The reaction was terminated and polyester resin B (glass transition temperature 61 ° C., softening temperature 147 ° C., weight average molecular weight 29500, Mw / Mn = 10.8, acid value 22 mmHg, THF insoluble content 40 %).

  Table 1 shows raw materials and physical properties of the polyester resins A1 to A9 and the polyester resin B.

Example 1
<Mixing step S1>
A master batch was prepared in which carbon black (trade name: MA-77, manufactured by Mitsubishi Chemical Corporation, pH = 2.5) was pre-kneaded and dispersed at a concentration of 23% by weight in polyester resin A2.
Masterbatch 43.5 parts by weight (21.7 kg)
52.7 parts by weight of polyester resin B (26.3 kg)
Polyethylene wax (low softening temperature wax, trade name: Sunwax LEL-250, manufactured by Sanyo Chemical Industries, softening temperature: 124 ° C.) 1.3 parts by weight (0.65 kg)
Polypropylene wax (high softening temperature wax, trade name: Viscol 550P, manufactured by Sanyo Chemical Industries, softening temperature: 152 ° C.) 1.3 parts by weight (0.65 kg)
Charge control agent (trade name: LR-147, manufactured by Nippon Carlit Co., Ltd.)
1.3 parts by weight (0.6 kg)

  The content of carbon black in 43.5 parts by weight of the master batch is 10 parts by weight.

  The above raw materials were mixed for 10 minutes with a Henschel mixer (trade name: FM20C, manufactured by Mitsui Mining Co., Ltd.) to obtain 50 kg of a mixture.

<Melt-kneading step S2>
The mixture obtained in the mixing step S1 was subjected to a cylinder setting temperature of 80 ° C. to 120 ° C. (maximum temperature 120 ° C.) and a rotation speed of 250 rpm in a kneader (trade name: biaxial kneader PCM-60, manufactured by Ikegai Co., Ltd.). The mixture was melt-kneaded at a supply rate of 5 kg / h to obtain a melt-kneaded product.

<Cooling and grinding step S3>
The melt-kneaded product obtained in the melt-kneading step S2 was cooled to room temperature and solidified, and then coarsely pulverized with a cutter mill (trade name: VM-16, manufactured by Orient Corporation). Subsequently, the obtained coarsely pulverized product was finely pulverized by a counter jet mill (trade name: AFG, manufactured by Hosokawa Micron Corporation).

<Classification step S4>
The pulverized product obtained in the cooling and pulverizing step S3 was classified with a rotary classifier (trade name: TSP separator, manufactured by Hosokawa Micron Corporation) to obtain an unextracted toner.

<External addition process S5>
Hydrophobic silica fine powder A (BET specific surface area 140 m ² / g) surface-treated with a silane coupling agent and dimethyl silicone oil with respect to 100 parts by weight (500 g) of the non-added toner obtained in the classification step S4 1.2 parts by weight (6 g), 0.8 parts by weight (4 g) of hydrophobic silica fine powder B (BET specific surface area 30 m ² / g) surface-treated with a silane coupling agent, and titanium oxide (BET specific surface area 130 m) ² / g) 0.5 part by weight (2.5 g) was added and mixed with a Henschel mixer (trade name: FM mixer, manufactured by Mitsui Mining Co., Ltd.), and the toner of Example 1 (volume average particle size 6.8 μm). , CV value 24%) was obtained.

(Example 2)
A toner of Example 2 (volume average particle size 6.7 μm, CV value 23%) was obtained in the same manner as in Example 1 except that the polyester resin A3 was used instead of the polyester resin A2.

(Example 3)
A toner of Example 3 (volume average particle diameter of 6.9 μm, CV value of 24%) was obtained in the same manner as in Example 1 except that the polyester resin A4 was used instead of the polyester resin A2.

Example 4
A toner of Example 4 (volume average particle size 6.7 μm, CV value 22%) was obtained in the same manner as in Example 1 except that the polyester resin A5 was used instead of the polyester resin A2.

(Example 5)
A toner of Example 5 (volume average particle size 6.8 μm, CV value 22%) was obtained in the same manner as in Example 1 except that the polyester resin A6 was used instead of the polyester resin A2.

(Example 6)
A toner of Example 6 (volume average particle diameter of 6.9 μm, CV value of 24%) was obtained in the same manner as in Example 1 except that the polyester resin A7 was used instead of the polyester resin A2.

(Example 7)
A toner of Example 7 (volume average particle diameter of 6.6 μm, CV value of 22%) was obtained in the same manner as in Example 1 except that the polyester resin A9 was used instead of the polyester resin A2.

(Example 8)
A toner of Example 8 (volume average particle size 6.7 μm, CV value 23%) was obtained in the same manner as in Example 7, except that the type of carbon black was changed. The carbon black used in Example 8 is a carbon black having a trade name of MA-100 (pH = 3.5, manufactured by Mitsubishi Chemical Corporation).

(Comparative Example 1)
A toner of Comparative Example 1 (volume average particle size 6.9 μm, CV value 24%) was obtained in the same manner as in Example 1 except that the polyester resin A1 was used instead of the polyester resin A2.

(Comparative Example 2)
A toner of Comparative Example 2 (volume average particle size 6.8 μm, CV value 23%) was obtained in the same manner as in Example 1 except that the polyester resin A8 was used instead of the polyester resin A2.

(Comparative Example 3)
A toner of Comparative Example 3 (volume average particle size 6.8 μm, CV value 24%) was obtained in the same manner as Example 7 except that the type of carbon black was changed. The carbon black used in Comparative Example 3 is carbon black having a trade name of # 2600 (manufactured by Mitsubishi Chemical Corporation, pH = 6.5).

  For the toners of Examples 1 to 8 and Comparative Examples 1 to 3, 5 parts by weight of each toner and 95 parts by weight of ferrite core carrier (volume average particle size 70 μm) were mixed into a V-type mixer (trade name: V-5, stock) A two-component developer was produced by mixing for 20 minutes at a company Tokuju Kogakusho.

  The following evaluation was performed using the two-component developers including the toners of Examples 1 to 8 and Comparative Examples 1 to 3.

[Hot offset resistance]
A two-component developer containing each toner was filled into a modified monochrome multifunction machine (trade name: MXM-700, manufactured by Sharp Corporation) to produce an unfixed image. The sample image includes a rectangular solid image portion having a length of 20 mm and a width of 50 mm on a recording paper (trade name: PPC paper SF-4AM3, manufactured by Sharp Corporation), and toner adheres to the recording paper in the solid image portion. The amount was adjusted to 0.5 mg / cm ² .

The produced unfixed image was fixed by increasing the temperature in increments of 130 ° C. to 5 ° C. using an external fixing device (process speed 395 mm / second) provided with the fixing portion of the monochrome multifunction peripheral, and the test paper (A4 Size, 52 g / m ² paper) The presence or absence of offset on the surface was visually confirmed. Thus, the hot offset start temperature of the toner was obtained, and the hot offset resistance was evaluated according to the following criteria.

Evaluation criteria for hot offset resistance are as follows.
○: Good. The hot offset start temperature is 240 ° C. or higher.
Δ: No problem in actual use. The hot offset start temperature is 220 ° C. or higher and lower than 240 ° C.
X: Defect. The hot offset start temperature is less than 220 ° C.

[Charging stability]
A monochrome composite machine (trade name: MXM-700, manufactured by Sharp Corporation) is filled with a two-component developer containing each toner, and recording paper (trade name: PPC paper SF-4AM3, manufactured by Sharp Corporation) is used as a recording medium. The actual machine was evaluated in an environment of 25 ° C. and 45% RH. For each item of charge amount ratio, image density, and fog density, the numerical value before printing was compared with the numerical value after printing 100000 originals with an image area of 5%.

[Image density]
A 100% solid image with a side of 3 cm was printed, and the image density of the printed portion was measured using a reflection densitometer trade name: RD918, manufactured by Macbeth Co., Ltd., and evaluated according to the following criteria.

The image density evaluation criteria are as follows.
○: Good. The image density is 1.4 or higher.
Δ: No problem in actual use. The image density is 1.2 or more and less than 1.4.
X: Defect. The image density is less than 1.2.

[Cover]
Using a whiteness meter (trade name: Z-Σ90 COLOR MEASURING SYSTEM, manufactured by Nippon Denshoku Industries Co., Ltd.), the whiteness of the non-image area (0% density) is measured and measured in advance. The difference from the degree was determined, and the difference was defined as the fog density, and the evaluation was performed according to the following criteria.

The evaluation standards for fog density are as follows.
○: Good. The fog density is less than 0.5. There is almost no fogging with the naked eye.
Δ: No problem in actual use. The fog density is 0.5 or more and less than 1.0. A little bit can be seen with the naked eye.
X: Defect. The fog density is 1.0 or more. The fog can be clearly confirmed with the naked eye.

[Overall]
Using the evaluation results of image density and fog density, charging stability was evaluated according to the following criteria.
○: Image density and fog evaluation result is ○.
Δ: At least one of the evaluation results of the image density and the fog is Δ, and there is no x.
X: At least one of the evaluation results of image density and fog is x.

〔Comprehensive evaluation〕
Using the evaluation results of the offset resistance and the charging stability, a comprehensive evaluation was performed according to the following comprehensive evaluation criteria.
○: Good. The evaluation results of offset resistance and charging stability are ◯.
Δ: No problem in actual use. Among the evaluation results of the offset resistance and the charging stability, at least one is Δ and there is no x.
X: Defect. At least one of the evaluation results of the offset resistance and the charging stability is x.

  Table 2 shows toner raw materials and evaluation results. In Table 2, polyester resin A1 is shown as resin A1. Polyester resins A2 to A9 and polyester resin B are also referred to as resins A2 to A9 and resin B, respectively.

  In Examples 1 to 8, good results were obtained. However, in Examples 1 and 2, the content of unreacted rosin in the toner was slightly less than in the other examples, so the charging stability was slightly reduced. In Example 6, since the content of unreacted rosin in the toner was slightly higher than in the other examples, the hot offset resistance was slightly lowered and a slight fog was generated.

  In Comparative Example 1, since the content of unreacted rosin in the toner is smaller than that in the example, the charging stability is lowered. In Comparative Example 2, since the content of unreacted rosin in the toner was larger than that in the Example, the hot offset resistance was lowered, the image density was slightly lowered, and fogging occurred. In Comparative Example 3, since the pH of the carbon black was higher than that of the example, the image density was slightly reduced and fogging occurred.

Claims (3)

Polyester resin A obtained by polycondensation of aromatic dicarboxylic acid, rosin, and trivalent or higher alcohol as a starting material, wherein the content of rosin in the total amount of the starting material is 60% by weight or more A binder resin having A and a polyester resin B obtained by condensation polymerization of an aromatic dicarboxylic acid as a starting material and a polyhydric alcohol;
a toner containing carbon black having a pH of 2.5 or more and 6.0 or less,
The toner, wherein a content of unreacted rosin in the toner is 1% by weight or more and 10% by weight or less based on the carbon black. Polyester resin A obtained by condensation polymerization of aromatic dicarboxylic acid, rosin, and trivalent or higher alcohol as a starting material, wherein the content of rosin in the starting material is 60% by weight or more And a binder resin having a polyester resin B obtained by condensation polymerization of aromatic dicarboxylic acid and polyhydric alcohol as a starting material, and carbon black having a pH of 2.5 or more and 6.0 or less. A mixing step of preparing a mixture, the content of unreacted rosin in the mixture being 1 wt% or more and 10 wt% or less with respect to the carbon black;
A melt-kneading step of melt-kneading the mixture to produce a kneaded product;
A cooling and pulverizing step in which the kneaded product is cooled and solidified and pulverized to produce a pulverized product;
And a classifying step for classifying the pulverized product. In the mixing step,
Mixing and kneading the polyester resin A and the carbon black to prepare a master batch,
The toner production method according to claim 2, wherein the mixture is prepared by mixing the polyester resin B and the master batch.

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