JP2005352247A - Negative charge type black toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a negative charge type black toner excellent in offset resistance in fixing, low-temperature fixability, sharp meltability, blocking resistance, charging characteristics, pulverizing property and carbon black dispersibility and capable of forming good developed images for a long period of time, by using a linear polyester resin prepared without using bisphenol A or a derivative thereof as an alcohol component and a specified carbon black. <P>SOLUTION: In the negative charge type black toner containing a binder resin and the carbon black, the binder resin is the linear polyester resin which comprises an acid component consisting of (1) disproportionated rosin and (2) terephthalic acid and/or isophthalic acid and an alcohol component consisting of (3) a glycidyl ester of a tertiary fatty acid and (4) a 2-10C aliphatic diol, and has an acid value of 10-60 mgKOH/g and a hydroxyl value of ≤20 mgKOH/g, and wherein a specific surface area of the carbon black by the BET method is 30-250 m<SP>2</SP>/g. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is a negative electrode used for developing an electrostatic charge image in an electrophotographic copying machine, a laser beam printer, an electrostatic recording apparatus and the like in which an image is formed using an electrophotographic method, an electrostatic recording method, or the like. The present invention relates to a chargeable black toner.

  Conventionally, the electrophotographic method or the electrostatic recording method has been widely used as a method for obtaining a copy or recorded image in a copying machine for copying an original or a printer for outputting a computer including a personal computer or a printer for a facsimile receiving apparatus. Has been. Typical examples of the copying machine and printer using the electrophotographic method or the electrostatic recording method include an electrophotographic copying machine, a laser beam printer, a printer using a liquid crystal array, and an electrostatic printer. In the electrophotographic method or the electrostatic recording method, an electrostatic latent image (electrostatic image) is formed by various means on an electrostatic image carrier such as an electrophotographic photosensitive member or an electrostatic recording material. While developing the image with a developer, the obtained toner image is transferred to a transfer medium such as paper as necessary, and fixed by heating, pressing, heating and pressing, or solvent vapor to obtain a final toner image The toner remaining without being transferred onto the electrostatic image bearing member is removed by the cleaning means. By repeating these steps, a plurality of copies or records can be obtained sequentially.

  As a method for developing the electrostatic latent image, a method using a liquid developer in which a fine toner is dispersed in an electrically insulating liquid (wet development method), a colorant in a binder resin, and a magnetic material as necessary. A method of using dispersed powder toner together with carrier particles, a method of developing without using carrier particles using a magnetic toner in which a magnetic material is dispersed in a binder resin (dry development method), etc. are known. . Among these methods, in recent years, a dry development method using powder toner (magnetic toner, non-magnetic toner) is mainly employed.

  By the way, in recent years, electrophotographic copying machines, laser beam printers, and the like have become smaller and more personalized, and at the same time, higher speed has been required, and further reduction in energy has been required. For this reason, various attempts have been made to improve these apparatuses for forming a reliable and high-quality image with low energy over a long period of time by a mechanism as simple as possible. In addition to such improvements in the apparatus, various attempts have been made to improve the toner used for development.

  Further, as a device for fixing a toner image, a heat and pressure fixing device using a heating roller, a roll-shaped or long heat-resistant film, a so-called fixing belt is used, and a heating body and a transfer are transferred via the fixing belt. 2. Description of the Related Art A heat and pressure fixing device is widely used in which a sheet development surface is opposed and a transfer sheet is conveyed from the back while being pressed by a pressure roller to heat and fix the sheet. In the fixing method using these heat fixing devices, the heat roller or the fixing belt is in direct contact with the toner image at the time of fixing, so that the heat is efficiently transmitted to the toner, and the toner is melted quickly and smoothly with low energy. Can be done. However, since the molten toner and the heat roller or the fixing belt are in direct contact with each other at the time of fixing, a part of the melted toner is transferred and adhered to the surface of the heat roller or the fixing belt. When the transferred and adhered toner is transferred again to the transferred material when it contacts the transferred material, or when the transferred material does not exist, the transferred and transferred toner is transferred to the pressure roller and transferred to the pressure roll. There is a problem in that when the transferred object passes through the fixing device, a toner adhering to the pressure roll causes a so-called offset phenomenon such that the back surface of the transferred object becomes dirty, and the transferred object becomes dirty.

In order to prevent such toner offset phenomenon, a conventional heat roll surface is formed of a releasable material such as silicone rubber or fluororesin, and a liquid having good releasability such as silicone oil is applied to the surface. Generally, the surface of a hot roll is covered with a releasable liquid film layer. According to this method, the occurrence of the offset phenomenon can be substantially prevented, but a problem arises in that a releasable liquid coating apparatus is required, and the silicone oil evaporates due to heat and contaminates the inside of the apparatus. Also, providing such a releasable liquid coating apparatus is incompatible with the downsizing of the apparatus. For this reason, the releasable liquid is not applied by a coating device, but the toner itself contains a releasable substance, the releasable substance is melted by heating during fixing, and the releasable liquid is supplied from the toner. In order to prevent the offset phenomenon, a number of waxes such as low molecular weight polyethylene, low molecular weight polypropylene, hydrocarbon waxes, natural waxes and modified waxes obtained by modifying them are proposed as such releasable substances. (For example, see Patent Documents 1 and 2).
Japanese Patent Publication No.52-3304 JP-A-60-252360

On the other hand, from the viewpoint of improving the low-temperature fixability of the toner, it is effective to lower the softening temperature (Tm) of the toner binder resin. However, in general, when Tm is lowered, the glass transition temperature (Tg) of the toner is also lowered at the same time, so that it is easy to cause so-called toner blocking in which the toner forms a lump in a storage state and toner offset at the time of fixing. This is one of the reasons why the fixing temperature cannot be lowered as expected. As a method for simultaneously satisfying this low-temperature fixability and blocking resistance or offset resistance, a method using a polyester resin having a relatively low fixing temperature even when Tm or Tg is high (for example, see Patent Document 3) has been proposed. ing. However, this method does not satisfy the low-temperature fixing property, blocking resistance, offset resistance and the like simultaneously and sufficiently. In addition, examples in which alkylene glycol and etherified diphenol are used in combination as an alcohol component of a polyester resin are also known (see, for example, Patent Documents 4 and 5), but the toner is not sufficiently pulverizable or has a low Tg. The blocking resistance of the obtained toner is not satisfactory. In addition, a dihydric alcohol is used as the alcohol component, and a non-linear cross-linked polyester resin composed of rosin, unsaturated dicarboxylic acid and other dicarboxylic acid as the acid component (see, for example, Patent Document 6), a specific alcohol component or Examples using acid components (see, for example, Patent Documents 7, 8, 9), examples using block polymers (see, for example, Patent Document 10), examples using amorphous polyester and crystalline polyester in combination (for example, Patents) A large number of polyester resins for toner binders have been proposed, such as offset resistance, low temperature fixability, sharp melt properties, blocking resistance, charging properties, pulverization properties, and transparency required as toner properties. Resins that can be used for toners that can simultaneously satisfy the properties have been developed.
JP-A-56-1952 Japanese Patent Laid-Open No. 1-226761 JP-A-1-155360 JP-A-4-70765 Japanese Patent Laid-Open No. 6-27728 Japanese Patent Laid-Open No. 9-278872 Japanese Patent Laid-Open No. 10-268558 JP 2001-324832 A JP 2002-284866 A

  As described above, attempts have been made to produce a toner for developing an electrostatic charge image with good characteristics by using a polyester resin as a binder resin for the toner. Conventionally, a polyester binder resin for toner with good toner characteristics has been used. It is generally considered that it is necessary to use bisphenol A or a derivative thereof as an alcohol component when obtaining. However, in recent years, it has become clear that bisphenol A is not necessarily used from the viewpoint of environmental hormones, and without using bisphenol A or its derivatives, offset resistance, low-temperature fixability, and sharp melt properties are the same as before. Development of a polyester resin for toner, which is excellent in properties such as blocking resistance, charging properties, pulverization properties, transparency, and the like and capable of forming a good developed image over a long period of time, and a toner is desired.

  Furthermore, the economics of toners have recently become important, and there has been a demand for provision of an inexpensive toner binder resin. However, conventional toner binders cannot always meet such requirements. It was.

  In addition, from the viewpoint of resource saving, there is a demand for a toner for developing an electrostatic charge image that can form a toner image having a high density similar to the conventional one with a small amount of toner.

  In addition, since carbon black has smaller primary particles and a larger specific surface area than other pigments, it is difficult to uniformly disperse and mix in the toner, and it is unevenly distributed on the toner surface or free carbon black is generated. Or it is easy to be blended in the toner while agglomerated. Since carbon black is a fine powder with high tackiness, the presence of free carbon black causes a decrease in toner fluidity, hinders good triboelectric charging, and in particular the reproducibility of halftone images. In addition, there is a problem that sufficient image density cannot be obtained when carbon black is not sufficiently dispersed.

Furthermore, since carbon black is electrically conductive, when it is present on the toner surface or when it is not uniformly dispersed in the toner, the charge is likely to leak. There are problems such as fogging, toner scattering, and transfer loss. In order to improve such points, it has been studied to obtain good dispersibility by defining the specific surface area of carbon black. (For example, Patent Documents 12 and 13) Although a good dispersibility can be obtained by specifying the specific surface area in this way, it is possible to reduce the consumption of toner using a polyester resin while maintaining a good image density. It was difficult.
JP 2002-116581 A JP 2002-116573 A

  In view of such a current situation, the object of the present invention is to provide an offset resistance, a low temperature fixability, a sharp melt property, and a blocking resistance at the time of fixing without using bisphenol A or a derivative thereof as a component of the polyester resin in the toner. Another object of the present invention is to provide a negatively chargeable black toner that is excellent in charging characteristics, pulverization characteristics, and carbon black dispersibility characteristics and can form a good developed image over a long period of time.

  Furthermore, another object of the present invention is to provide a negatively chargeable black toner using an inexpensive polyester resin for toner as a binder resin.

  Another object of the present invention is to provide a negatively chargeable black toner capable of forming an image having a density similar to that of the conventional one by using a small amount.

The present invention relates to a negatively chargeable black toner containing at least a binder resin and carbon black, wherein the binder resin includes (1) disproportionated rosin and (2) terephthalic acid and / or isophthalic acid, The alcohol component is composed of (3) a glycidyl ester of a tertiary fatty acid and (4) an aliphatic diol having 2 to 10 carbon atoms, and has an acid value of 10 to 60 mgKOH / g and a hydroxyl value of 20 mgKOH / g or less. The present invention relates to a negatively chargeable black toner which is a polyester resin and has a specific surface area of carbon black of 30 to 250 m ² / g by BET method.

The present invention also relates to the above negatively chargeable black toner, wherein the binder resin has a true density of 1.1 to 1.3 g / cm ³ .

 The present invention also relates to the negatively chargeable black toner, wherein the carbon black has a DBP oil absorption of 40 to 110 ml / 100 g.

  The present invention also relates to a two-component developer comprising any one of the above negatively chargeable black toners and a carrier.

  Since the negatively chargeable black toner of the present invention does not use a bisphenol A derivative such as bisphenol A or an ethylene oxide adduct of bisphenol A as an alcohol component of a linear polyester resin that is a binder resin of the toner, the viewpoint of environmental hormones Therefore, it is possible to obtain a negatively chargeable black toner which is environmentally friendly.

  Further, by using this linear polyester resin, even without using bisphenol A or a derivative of bisphenol A, offset resistance, low-temperature fixing property, sharp melt property, blocking resistance, charging property, which is the same as or higher than conventional ones, A negatively chargeable black toner having characteristics such as grindability can be obtained. As a result, the storage stability of the toner classified product is improved, and the fluidity of the toner during development and the blocking of the toner do not occur.

  Further, by using this linear polyester resin and specific carbon black, the charging characteristics and the rising of the development are good, and since no in-machine scattering occurs, a good developed image can be formed over a long period from the beginning.

  Further, since bisphenol A or a derivative thereof is not used in the present invention, a linear polyester resin can be produced at a low cost, and the resin has a true density higher than that using bisphenol A or a derivative thereof as an alcohol component. Therefore, if the negatively chargeable black toner of the present invention is used, the amount of toner used per sheet can be reduced, and the copying cost can be reduced.

  Hereinafter, the present invention will be described in more detail. First, in the linear polyester resin used as the binder resin for the negatively chargeable black toner of the present invention, (a) the acid component is disproportionated rosin (1) and terephthalic acid and / or isophthalic acid (2), (b ) The alcohol component is composed of a glycidyl ester of a tertiary fatty acid (3) and an aliphatic diol (4) having 2 to 10 carbon atoms, having an acid value of 10 to 60 mg KOH / g and a hydroxyl value of 20 mg KOH / g or less. It is important that

In the linear polyester resin used in the present invention, the disproportionated rosin used as the acid component of (a) may be produced by any conventionally known production method. For example, rosin is converted to Pd. A method of saponifying the reaction product by reacting in the presence of a disproportionation catalyst such as a carbon catalyst under conditions of 250 to 300 ° C., 5 to 15 kg / cm ² , and 2 to 6 hours may be mentioned.
Commonly available gum rosin, tall oil rosin, and the like have a lot of abietic acid containing a conjugated double bond and are very easily oxidized. Therefore, it is preferable to disproportionate in order to prevent discoloration and alteration due to air oxidation. . Here, abietic acid is disproportionated into dehydroabietic acid and dihydroabietic acid, and is contained in the disproportionated rosin.

 On the other hand, terephthalic acid and isophthalic acid are composed of terephthalic acid, isophthalic acid and their lower alkyl esters. Examples of lower alkyl esters of terephthalic acid and isophthalic acid include, for example, dimethyl terephthalate, dimethyl isophthalate, diethyl terephthalate, diethyl isophthalate, dibutyl terephthalate, and dibutyl isophthalate. Dimethyl acid and dimethyl isophthalate are preferred. These dicarboxylic acids or lower alkyl esters thereof may be used alone or in combination of two or more.

 The molar ratio of disproportionated rosin (1) to terephthalic acid and / or isophthalic acid (2) is preferably (1) / (2) = 0.1 to 0.6. More preferably, it is 0.15-0.55. When the molar ratio of the disproportionated rosin (1) and terephthalic acid and / or isophthalic acid (2) is lower than 0.1, the fixability tends to deteriorate and fog tends to occur. If it exceeds .6, the offset resistance is deteriorated and the image density tends to be lowered.

  As the acid component, dicarboxylic acids other than these can be used together with terephthalic acid and isophthalic acid as long as the object of the present invention is not impaired. These other dicarboxylic acids include benzene dicarboxylic acids such as phthalic acid and phthalic anhydride; 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. Acids; unsaturated dicarboxylic acids such as fumaric acid, maleic acid, citraconic acid, itaconic acid, glutaconic acid; cyclohexane dicarboxylic acid; naphthalenedicarboxylic acid; diphenoxyethane-2,6-dicarboxylic acid and lower monoesters of these acids; Examples include diesters and acid anhydrides. Since these dicarboxylic acids greatly affect the fixing property and blocking resistance of the toner, they are used in an appropriate amount in consideration of the required performance of the toner.

  Moreover, as an example of the glycidyl ester of the tertiary fatty acid used as an alcohol component of (b), what is represented, for example by following General formula (1) is mentioned.

(In the formula, R ¹ , R ² and R ³ represent an alkyl group.)
In the above formula, the total number of carbon atoms of R ¹ , R ² and R ^{3 and} the carbon number of these groups is not particularly limited, but neodecanoic acid glycidyl ester having a total carbon number of R ¹ + R ² + R ³ is particularly 8 preferable.

  Examples of the aliphatic diol having 2 to 10 carbon atoms include, for example, 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-octane Diol, 1,9-nonanediol, 1,10-decanediol, 3-hydroxy-2,2-dimethylpropyl-3-hydroxy-2,2-dimethylpropanoate, diethylene glycol, triethylene glycol, dipropylene glycol, etc. Is mentioned. As the aliphatic diol, neopentyl glycol and ethylene glycol are preferable from the viewpoint of reactivity with acid and glass transition temperature of the resin. These aliphatic diols may be used alone or in combination of two or more.

The molar ratio of the tertiary fatty acid glycidyl ester (3) and the aliphatic diol (4) having 2 to 10 carbon atoms is preferably (3) / (4) = 0.05 to 0.20. More preferably, it is 0.08-0.15. When the molar ratio of the tertiary fatty acid glycidyl ester (3) and the aliphatic diol (4) having 2 to 10 carbon atoms is lower than 0.05, image fog is likely to occur and exceeds 0.2. In some cases, offset resistance and blocking resistance tend to deteriorate. By using rosin glycidyl ester together with glycidyl ester of tertiary fatty acid, offset resistance and blocking resistance are improved.
It is preferable to use 5 to 30 mol% of the glycidyl ester of the tertiary fatty acid in the component (b). The molar ratio (2) / (4) of the aliphatic diol of the alcohol component (4) to the dicarboxylic acid of the component (2) of the acid component is the molar ratio (1) of the acid components (1) and (2). Although it varies depending on the value of the molar ratio (3) / (4) of / (2) and alcohol components (3) and (4), it is usually preferably 0.8 to 1.5, more preferably 0.9 to 1.3.

The linear polyester resin used in the negatively chargeable black toner of the present invention having the above-described configuration has an acid value of 10 to 60 mgKOH / and a hydroxyl value of 20 mgKOH / g or less, preferably 18 mgKOH / g or less. is necessary.
In addition, when the acid value is less than 10 mgKOH / g, the negative chargeability of the toner decreases, and image fogging, in-machine scattering, and toner consumption increase. On the other hand, when the acid value exceeds 60 mgKOH / g, In a low-humidity environment, the negative chargeability of the toner becomes too high, resulting in a decrease in image density and an increase in hydrophilicity, so that image fogging and in-machine scattering increase especially in a high-humidity environment. Furthermore, when the hydroxyl value exceeds 20 mgKOH / g, the hydrophilicity increases, so that image fogging and in-machine scattering increase particularly in a high humidity environment. In the production examples for the linear polyester resin of the present invention, the hydroxyl value is in the range of 3 to 18 mg KOH / g. As a result was obtained, the hydroxyl value was 20 mg KOH in the polyester resin of the present invention. It is important that it is suppressed to / g or less.

  The linear polyester resin used for the negatively chargeable black toner of the present invention has a softening temperature of 115 to 150 ° C., preferably 120 to 145 ° C., and a tetrahydrofuran (THF) soluble component having a number average molecular weight of 1,000 to 6. 2,000, preferably 2,000 to 4,000. This is because when the softening temperature is less than 115 ° C., the cohesive strength of the resin is extremely reduced, while when it exceeds 150 ° C., the melt flow and low-temperature fixability of the toner using the resin are reduced. This is because it is not suitable for a toner binder. When the number average molecular weight of the linear polyester resin is small, the offset resistance of the toner tends to decrease, and when the number average molecular weight is large, the fixability tends to decrease.

The linear polyester resin used for the negatively chargeable black toner of the present invention is a type having a molecular weight distribution curve of two peaks composed of a specific low molecular weight condensation polymer component and a specific high molecular weight condensation polymer component. Alternatively, it may be of any type having a single molecular weight distribution curve. From the viewpoint of preventing toner aggregation, it is desirable that the glass transition temperature (Tg) measured by a differential scanning calorimeter (DSC) is 45 to 70 ° C., preferably 50 to 65 ° C. Furthermore, the true density of the resin is preferably 1.1 to 1.3 g / cm ³ . When the true density of the resin is low, the toner can be used in a small amount when an image having the same density is formed, and as a result, economical copying can be performed.

  The linear polyester resin used in the negatively chargeable black toner of the present invention is prepared by a known and commonly used production method using the predetermined acid component and alcohol component as raw materials. The reaction method may be transesterification or direct esterification. Any of the chemical reactions can be applied. In addition, polycondensation can be promoted by a method of increasing the reaction temperature by pressurization, a depressurization method, or a method of flowing an inert gas under normal pressure. In the above reaction, a known and commonly used reaction catalyst such as at least one metal compound selected from antimony, titanium, tin, zinc and manganese may be used to accelerate the reaction. Specific examples of the reaction catalyst include di-n-butyltin oxide, stannous oxalate, antimony trioxide, titanium tetrabutoxide, manganese acetate, and zinc acetate. The amount of these reaction catalysts added is usually preferably about 0.001 to 0.5 mol% in the resulting polyester resin.

  In the method for producing a linear polyester resin used in the negatively chargeable black toner of the present invention, a direct esterification method at normal pressure is mentioned as one of the preferred methods during the various reactions described above. In this direct esterification method, for example, the alcohol component and the disproportionated rosin are charged all at the start of the reaction, and the temperature is raised to about 160 ° C. and then a high melting point terephthalic acid, isophthalic acid and a reaction catalyst are charged. Be taken. As the reaction catalyst, acids, alkalis, amines, metal organic acid salts and the like are effective. In addition, titanate, borate and the like are also effective. Specifically, di-n-butyltin oxide, stannous oxalate, antimony trioxide, zinc octylate, iron octylate and the like are used, and the addition amount is 0.01 to 0.1 with respect to the total acid component. A mol% is suitable. In this case, a sufficient reaction rate can be obtained even at normal pressure, but the reaction temperature can be increased by applying a pressurizing operation. The promotion of the reaction by the depressurization operation is applied in the case where almost no unreacted alcohol disappears at the end of the reaction, and the removal of the produced water out of the system is delayed. The promotion of the reaction by passing through an inert gas can be applied to any process of the reaction in such an amount that it minimizes the dissipation of alcohol out of the system. The reaction is terminated after confirming that the softening point of the resin has reached a predetermined temperature.

 The binder resin used in the negatively chargeable black toner of the present invention may be the above linear polyester resin alone, or two or more of the above linear polyester resins may be used in combination. Furthermore, as long as the object of the present invention can be achieved, polystyrene polymers, polystyrene copolymers such as styrene-acrylic resins, polyester resins other than the above polyester resins, and the like, are conventionally used as binder resins for toners. The resin being used may be used together with the polyester resin.

As carbon black that can be used in the negatively chargeable black toner of the present invention, it is important that the specific surface area by the BET method is 30 to 250 m ² / g. More preferably, it is 40-240 m < ² > / g. By satisfying this range, carbon black is well dispersed and blended in the linear polyester resin of the present invention, and good charging characteristics and resistance characteristics as a toner can be obtained. When carbon black having a specific surface area of more than 250 m ² / g by the BET method is used, fogging tends to increase and toner scattering in the machine tends to increase, and the quality of the copied image deteriorates. In addition, dispersibility, distribution in individual toner particles, and blendability also deteriorate, and the carbon black content among the toner particles is unevenly distributed, making it difficult to recycle the classified fine powder during production. On the other hand, if the specific surface area is less than 30 m ² / g, it is difficult for the carbon black particles to sufficiently color the toner. Further, if the amount added is increased in order to supplement the colorability, the resistance value of the toner is lowered, the charge amount is lowered, and fogging and in-machine scattering occur.
Here, a certain correlation can be found between the specific surface area of the carbon black and the fog. Regarding the relationship between the specific surface area of carbon black and fog, there is a large factor in the dispersibility of carbon black. If the specific surface area of the carbon black exceeds 250 m ² / g, uniform dispersion in the toner becomes difficult and dispersion failure tends to occur. As a result, the uneven distribution of the colorant in the toner causes the resistance value of the toner to vary, making it impossible to maintain a uniform and stable charge. As the carbon black is more unevenly distributed, the fog becomes larger. That is, if the specific surface area of carbon black by the BET method is 30 to 250 m ² / g, fog is reduced and a good copy image can be obtained.

The DBP oil absorption of carbon black used for the negatively chargeable black toner of the present invention is preferably 40 to 110 ml / 100 g. If the oil absorption of carbon black is larger than 110 ml / 100 g, the structure of the carbon black becomes large, the conductivity in the toner becomes high, charge leakage occurs, and fogging on the image and in-machine scattering occur. On the other hand, when the oil absorption amount of carbon black is smaller than 40 ml / 100 g, the conductivity becomes low and charge-up is likely to occur, and the image density is likely to decrease particularly at low temperature and low humidity.
Moreover, it is preferable to use oil furnace carbon as a kind of carbon black. Compared with channel black carbon, it is possible to achieve better dispersion in the toner.

The carbon black can be used alone or in admixture of two or more, and is usually 0.1 to 20 parts by weight, preferably 0.5 to 10 parts by weight with respect to 100 parts by weight of the binder resin. The amount added is good. These can be used alone or in admixture of two or more.

  The negatively chargeable black toner of the present invention contains a binder resin mainly composed of the above-described linear polyester resin, carbon black, and further includes a charge control agent, a release agent, an external additive, and the like as necessary. Blended.

The negatively chargeable black toner of the present invention preferably contains a charge control agent that gives a negative charge to the toner, if necessary. Salicylic acid derivative metal salt compounds, salicylic acid derivative metal complexes, phenol condensates, monoazo metal complexes, phosphonium compounds, and the like are preferable as charge control agents that impart a favorable negative charge. As the metal used for the metal salt compound of the salicylic acid derivative and the metal complex of the salicylic acid derivative, zinc, calcium, magnesium, titanium, chromium, aluminum, silicon and the like are preferable. As the salicylic acid derivative, those having a tert-butyl group or a tert-octyl group are preferable. Specifically, salicylic acid, 3,5-di-tert-butylsalicylic acid, 3-hydroxy-2-naphthoic acid, 3- Phenylsalicylic acid is a particularly preferred compound.
In particular, a metal salt compound of a salicylic acid derivative has two to three —OH groups (hydroxyl groups) in one molecule, and thus reacts with a carboxyl group that is an acid component in a polyester resin. It is a preferred charge control agent in that the control agent can be dispersed, and this reaction can promote cross-linking of the polyester resin and increase in molecular weight to improve the fixing property.
As the phenol condensate, a calixarene compound is preferable. As these charge control agents, those obtained by a known production method can be used.

  The charge control agent can be used more effectively by pulverizing with a pulverizer and adjusting to a desired particle size distribution. In the present invention, a preferable particle size distribution as a charge control agent is 0.5 to 40 μm, more preferably 1 to 20 μm, as a volume average particle size by a Coulter counter. When the volume average particle diameter is larger than 40 μm, it becomes difficult to disperse the charge control agent in the binder resin, and it becomes difficult to disperse the charge control agent in the toner. In addition, the content of the charge control agent per toner particle is biased, leading to an increase in fog and scattering in the apparatus. On the other hand, when a material having a volume average particle size of less than 0.5 μm is used, the dispersion in the binder resin is good, but the specific surface area of the charge control agent becomes large, and the toner is excessively charged. In some cases, the charge amount increases and the image density decreases.

  The addition amount of the charge control agent is usually 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight with respect to 100 parts by weight of the binder resin.

The negatively chargeable black toner of the present invention contains a release agent as necessary. Among these, it is preferable to use a wax having a melt viscosity at 140 ° C. of 100 mPa · s (CS) or less and an acid value of 2 mgKOH / g or less, and 0.5 to 10% by weight based on 100 parts by weight of the binder resin. Can be made.
Examples of such a wax include fatty acid esters such as polypropylene wax, polyethylene wax, paraffin wax, fatty acid amide wax, carnauba wax, and montan wax, partially saponified fatty acid ester wax, and fatty acid metal salts.
When the melt viscosity at 140 ° C. of the wax exceeds 100 mPa · s, there is a problem that the low temperature fixability is poor, and when the acid value of the wax exceeds 2 mgKOH / g, a low molecular weight substance is mixed in the wax. In many cases, this low molecular weight product is not preferable because it causes problems such as odor generation at the time of fixing and deterioration of storage stability of the toner.
Considering good dispersion of the wax in the toner, the true density of the wax is preferably in the range of 0.8 to 1.1 g / cm ³ . In order to achieve good dispersion, it is also preferable to use a wax modified with a functional group having a polar group such as a hydroxyl group, a carboxyl group, or an ester group.

  The negatively chargeable black toner of the present invention may further contain known additives used in the production of the toner, such as a lubricant, a fluidity improver, an abrasive, a conductivity imparting agent, and an image peeling prevention agent, if necessary. Can be added internally or externally. Examples of these additives include polyvinylidene fluoride and zinc stearate as a lubricant, and silica, aluminum oxide, titanium oxide, silicon aluminum co-oxide produced by a dry method or a wet method as a fluidity improver. , Silicon-titanium co-oxide and those hydrophobized, etc., and abrasives include silicon nitride, cerium oxide, silicon carbide, strontium titanate, tungsten carbide, calcium carbonate and those hydrophobized. Examples of the conductivity imparting agent include tin oxide and antimony trioxide. In addition, fine powders of fluorine-containing polymers such as polyvinylidene fluoride are preferable from the viewpoint of fluidity, abrasiveness, charge stability, and the like.

  In the negatively chargeable black toner of the present invention, it is preferable to contain hydrophobized silica, silicon aluminum co-oxide, and silicon titanium co-oxide fine powder as external additives as fluidity improvers. Examples of the hydrophobic treatment of these fine powders include treatment with a silane coupling agent such as silicone oil, tetramethyldisilazane, dimethyldichlorosilane, and dimethyldimethoxysilane. The amount of the hydrophobized fine powder such as silica that has been hydrophobized is 0.01 to 20%, preferably 0.03 to 5%, based on the toner weight.

  The weight average particle diameter of the toner particles in the negatively chargeable black toner of the present invention is preferably 3 to 15 μm. In particular, toner particles having a particle size of 5 μm or less are contained in 12 to 60% by number, toner particles having a particle size of 8 to 12.7 μm are contained in 1 to 33% by number, and toner particles having a particle size of 16 μm or more. Is more preferably 2.0 wt% or less, and the weight average particle diameter of the toner is 4 to 11 μm from the viewpoint of development characteristics. The particle size distribution of the toner particles can be measured using, for example, a Coulter counter.

  The toner particles constituting the negatively chargeable black toner of the present invention can be manufactured using a conventionally known toner particle manufacturing method. Generally, after sufficiently premixing the binder resin, colorant, charge control agent, release agent, and the like, which are constituent materials of the toner particles as described above, with a mixer such as a dry blender, ball mill, Henschel mixer, etc. , Knead well using a heat kneader such as a hot roll, kneader, uniaxial or biaxial extruder, cool and solidify, then mechanically coarsely pulverize using a pulverizer such as a hammer mill, and then with a jet mill, etc. A method of classifying after fine pulverization is a preferable method. The classified toner particles are sufficiently mixed with an external additive as necessary using a mixer such as a Henschel mixer to obtain the negatively chargeable black toner of the present invention.

  The negatively chargeable black toner of the present invention can be mixed with a carrier and used as a two-component developer. As the carrier that can be used together with the negatively chargeable black toner of the present invention, any conventionally known carrier can be used. Examples of the carrier that can be used include magnetic powder such as iron powder, ferrite powder, and nickel powder, and glass beads. These carrier particles may have a surface coated with a resin as necessary. Examples of the resin covering the carrier surface include styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, acrylic acid ester copolymer, methacrylic acid ester copolymer, fluorine-containing resin, silicone-containing resin, and polyamide. Examples thereof include a resin, an ionomer resin, a polyphenylene sulfide resin, and a mixture thereof. Among these, fluorine-containing resins and silicone resins are particularly preferable because they hardly form spent toner.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited at all by these Examples. In the following, all “parts” represent parts by weight.

  The acid value, hydroxyl value, glass transition temperature (Tg), softening point, and true density of the resins in the following production examples, examples, and comparative examples are as follows.

(Acid value and hydroxyl value)
The acid value refers to the number of milligrams of potassium hydroxide necessary to neutralize the acid groups contained in 1 g of a sample. The hydroxyl value refers to the number of milligrams of potassium hydroxide necessary to neutralize acetic acid bonded to a hydroxyl group when 1 g of a sample is acetylated.

(Glass-transition temperature)
The glass transition temperature is measured by using a differential scanning calorimeter (DSC-50, manufactured by Shimadzu Corporation) with an extension of the baseline below Tg when measured at a heating rate of 20 ° C./min, and an endothermic curve near Tg. The temperature at the intersection of tangents.

(Softening point)
The softening point was measured using an elevated flow tester (CFT-500D, manufactured by Shimadzu Corporation) with a load of 30 kg, a nozzle diameter of 1 mm, a nozzle length of 10 mm, a preheating temperature of 80 ° C. for 5 minutes, and a heating rate of 3 The temperature at the time of h / 2 when the height of the S-shaped curve in the plunger descent amount-temperature curve of the flow tester is h, when measured as ° C / min and the sample amount is 1 g.

(True density)
The true density refers to a value measured by a vapor phase substitution method using a dry automatic densimeter (Shimadzu-Micromeritics Accupic 1330 (10 cm ³ )). The measurement conditions are as follows.
Measurement gas: Helium Introduced pressure: Purge and run 19.5 psig (134.35 Kpag)
Equilibrium judgment pressure: 0.0050 psig / min (0.0345 Kpag / min)
Temperature and humidity: 23 ° C / 50% RH

(Specific surface area)
The specific surface area of carbon black by nitrogen adsorption is measured according to ASTM D 3037.

(DBP oil absorption)
The DBP oil absorption of carbon black is measured according to DIN 53601.

Resin production example 1
As a polyester resin raw material alcohol component, neopentyl glycol 70.9 mol%, neodecanoic acid glycidyl ester 9.7 mol%, disproportionated rosin 18.2 mol% as a raw acid component, stirring device, heating device, thermometer, minute A stainless steel reaction vessel equipped with a distillation apparatus and a nitrogen gas introduction tube was charged and heated to 160 ° C. with stirring to melt the contents. After melting, 81.8 mol% of terephthalic acid and 0.03 mol% of di-n-butyltin oxide are charged as raw acid components so that the temperature at the top of the fractionator does not exceed 100 ° C. While removing condensed water out of the system with a nitrogen gas stream, the temperature was gradually raised to 240 ° C. to carry out an esterification reaction, and the mixture was cooled to 200 ° C. when the acid value reached 50 mgKOH / g. After confirming that a predetermined softening point was reached by a flow tester, the reaction was terminated. The characteristic values of the obtained polyester resin A are shown in Table 1.
In addition, the composition amount mol% of each monomer is mol% with respect to all the acid components.

Resin production examples 2-4
Except making it the mixture ratio shown in Table 1, it carried out similarly to manufacture manufacture example 1, and obtained polyester resin B, C, and D. The characteristic values of the obtained polyester resin are shown in Table 1.

Resin production example 5
As a polyester resin raw material alcohol component, neopentyl glycol 70.9 mol%, neodecanoic acid glycidyl ester 9.7 mol%, disproportionated rosin 18.2 mol% as a raw acid component, stirring device, heating device, thermometer, minute A stainless steel reaction vessel equipped with a distillation apparatus and a nitrogen gas introduction tube was charged and heated to 160 ° C. with stirring to melt the contents. After melting, 50 mol% of terephthalic acid as raw acid component, 31.8 mol% of isophthalic acid, and 0.03 mol% of di-n-butyltin oxide were charged, and the temperature at the top of the fractionator exceeded 100 ° C. The condensed water produced is removed from the system by a nitrogen gas stream, and the temperature is gradually raised to 240 ° C. to carry out the esterification reaction. When the acid value reaches 50 mgKOH / g, the solution is cooled to 200 ° C. did. After confirming that a predetermined softening point was reached by a flow tester, the reaction was terminated. The characteristic values of the obtained polyester resin E are shown in Table 1.

Resin production example 6
Polyester resin raw material alcohol component 87.5 mol% ethylene glycol, 11.9 mol% neodecanoic acid glycidyl ester, disproportionate rosin 18.2 mol% as raw acid component, stirring device, heating device, thermometer, fractional distillation The reactor was charged into a stainless steel reaction vessel equipped with a nitrogen gas introduction tube, and the temperature was raised to 160 ° C. with stirring to melt the contents. After melting, 81.8 mol% of terephthalic acid as a raw acid component and 0.03 mol% of di-n-butyltin oxide are charged so that the temperature at the top of the fractionator does not exceed 100 ° C. While the condensed water to be removed was removed from the system by a nitrogen gas stream, the temperature was gradually raised to 240 ° C. to carry out an esterification reaction, and the mixture was cooled to 200 ° C. when the acid value reached 45 mgKOH / g. After confirming that a predetermined softening point was reached by a flow tester, the reaction was terminated. The characteristic values of the obtained polyester resin F are shown in Table 1.

Comparative resin production examples 7-8
Polyester resins G and H were obtained in the same manner as in Resin Production Example 1 except that the blending ratios shown in Table 2 were used. The characteristic values of the obtained polyester resin are shown in Table 2.

Comparative resin production example 9
73.3 mol% of bisphenol A ethylene oxide 2 mol adduct as a polyester resin raw material alcohol component, 10 mol% of neodecanoic acid glycidyl ester, 33.3 mol% of disproportionated rosin as a raw acid component, A stainless steel reaction vessel equipped with a thermometer, a fractionator, and a nitrogen gas inlet tube was charged and heated to 160 ° C. with stirring to melt the contents. After melting, 66.7 mol% of terephthalic acid as a raw acid component and 0.03 mol% of di-n-butyltin oxide are charged so that the temperature at the top of the fractionator does not exceed 100 ° C. While the condensed water to be removed was removed from the system by a nitrogen gas stream, the temperature was gradually raised to 240 ° C. to carry out an esterification reaction. When the acid value reached 35 mgKOH / g, the mixture was cooled to 200 ° C. After confirming that a predetermined softening point was reached by a flow tester, the reaction was terminated. The characteristic values of the obtained polyester resin I are shown in Table 2.

  “BPA-EO 2 mol adduct” in the table represents an ethylene oxide 2 mol adduct of bisphenol A.

  Table 3 shows the characteristic values of the studied carbon black.

(Component) (Blending amount)
Polyester resin A 87 parts by weight Carbon black CB1 8 parts by weight Charge control agent (chromium salt compound of aromatic hydroxycarboxylic acid) 1 part by weight Low molecular weight polypropylene (true density 0.905 g / cm ³ ) 4 parts by weight After mixing, kneading, pulverization, and classification were performed to obtain negatively chargeable black toner particles having an average particle diameter of 10.8 μm. Next, 0.5 parts of silica fine powder treated with dimethyldichlorosilane, 0.4 parts of PMMA fine particles (polymethacrylate methacrylate fine particles) and 0.5 parts of tungsten carbide fine powder are added to and mixed with 100 parts of the toner particles. As a result, a negatively chargeable black toner was obtained.

The charge amount of the black toner was measured to evaluate the chargeability, and the storage stability was also evaluated. The results are shown in Table 4.
Furthermore, using this black toner, a live-action test was performed using a commercially available copying machine having a structure of a hot-pressing roll as a fixing device (Leo Dry 6550 manufactured by Toshiba Corporation), and image density (initial and 10,000 sheets). The evaluation was made on the subsequent image density value), fog (initial and 10,000-image fog value), consumption, fixing property, and offset resistance. As a carrier, a silicone-coated ferrite carrier having an average particle diameter of 60 μm was used, and 94 parts of this carrier and 6 parts of black toner were mixed to prepare a developer. The results are shown in Table 4.

  In addition, measurement and evaluation of charge amount, storage stability test and evaluation, image density measurement, fog density measurement, toner consumption measurement, fixing property test and evaluation, offset resistance test and evaluation are as follows: It was done like that.

(Measurement and evaluation of charge amount)
The toner charge amount of the developer was calculated using a blow-off charge amount measuring device manufactured by Toshiba Chemical Corporation. At this time, the blow pressure was 1 kgf / cm ² , the maximum value was read at a measurement time of 20 seconds, and the mesh was 400 mesh. The measurement environment was 23 ° C. and 50% RH.

(Storage stability test and evaluation)
40 g of toner is sealed in a 200 ml glass container, left in a constant temperature bath at 50 ° C. for 24 hours, and then observed by checking the toner blocking property. △ was assigned to those to be treated, and × was designated to be aggregates that were not easily loosened.

(Measurement of image density)
The image density was measured using a Macbeth photometer. The concentration may be 1.35 or more.

(Measurement of fog density)
This was done by measuring the reflectance with a photovolt. 1.5% or less is a good value.

(Measurement of toner consumption)
This is expressed as the number of tonergrams consumed per 1,000 sheets in a 6% original document.

(Fixability test and evaluation)
The fixed image was rubbed with an eraser (dragonfly pencil MONO), and the value calculated by [image density after rubbing / image density before rubbing] × 100 was expressed as the fixing strength. 85% or more is a good value.

(Offset resistance test and evaluation)
The image for fixing test was continuously copied for 100 sheets, stopped for 5 minutes, then passed through 20 blank sheets, and the evaluation was made based on the state of the white paper. In the evaluation results, “O” indicates that no paper stain occurred, and “X” indicates that the paper stain occurred.

Examples 2-8
A negatively chargeable black toner was obtained and evaluated in the same manner as in Example 1 except that the polyester resin and carbon black shown in Table 4 were used. For these black toners, in the same manner as in Example 1, the charge amount, the storage stability, the image density (value of the initial image density and the image density after 10,000 sheets), and the fog (the fog image after the initial and 10,000 sheets). Value), consumption, fixability, and offset resistance. The results are also shown in Table 4.

Comparative Examples 1-5
A negatively chargeable black toner was obtained and evaluated in the same manner as in Example 1 except that the polyester resin and carbon black shown in Table 4 were used. For these black toners, in the same manner as in Example 1, the charge amount, the storage stability, the image density (value of the initial image density and the image density after 10,000 sheets), and the fog (the fog image after the initial and 10,000 sheets). Value), consumption, fixability, and offset resistance. The results are also shown in Table 4.

The negatively chargeable black toner of the present invention can be preferably used in an electrophotographic dry developer, a copying machine using a toner, a printer, and the like, and the binder resin in the toner does not use a bisphenol A derivative which is an environmental hormone. The toner is preferably used as an environmental countermeasure toner.

Claims (4)

In the negatively chargeable black toner containing at least a binder resin and carbon black, the binder resin has an acid component (1) disproportionated rosin and (2) terephthalic acid and / or isophthalic acid, an alcohol component, (3) A linear polyester resin composed of a glycidyl ester of a tertiary fatty acid and (4) an aliphatic diol having 2 to 10 carbon atoms and having an acid value of 10 to 60 mgKOH / g and a hydroxyl value of 20 mgKOH / g or less. A negatively chargeable black toner having a specific surface area of 30 to 250 m ² / g of carbon black according to the BET method. The negatively chargeable black toner according to claim 1, wherein the true density of the binder resin is 1.1 to 1.3 g / cm ³ .  The negatively chargeable black toner according to claim 1, wherein the carbon black has a DBP oil absorption of 40 to 110 ml / 100 g. A two-component developer comprising the negatively chargeable black toner according to claim 1 and a carrier.