JP2005326606A - Positive charge type magnetic toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a positive charge type magnetic toner superior in offset resistance, superior also in toner properties, such as color reproducibility, color forming property, transmittance, low-temperature fixability, sharp meltability, blocking resistance, charging characteristics and pulverizability, and capable of forming properly developed images over a prolonged period of time, without using bisphenol A or its derivative as the component of a polyester resin in the toner. <P>SOLUTION: In the positive charge type magnetic toner containing a binder resin, a positive charge type charge control agent and a magnetic material, the binder resin is a 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 mgKOH/g and a hydroxyl value of ≤20 mgKOH/g, and the positive charge type charge control agent is a quaternary ammonium salt compound or a resin containing a quaternary ammonium salt. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a positive electrode used for developing an electrostatic charge image in an electrophotographic copying machine, a laser beam printer, an electrostatic recording apparatus or 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 magnetic 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.

  Incidentally, electrophotographic copying machines, laser beam printers, and the like have recently been downsized and personalized, 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 a toner offset phenomenon, the surface of a conventional heat roll 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, attempts have been made to prevent the occurrence of the offset by improving the properties of the binder resin of the electrostatic image developing toner. Examples of the binder resin having excellent offset resistance include, for example, a cross-linked polyester obtained by reacting an etherified diphenol, a dicarboxylic acid component, and a trivalent or higher monomer component to form a cross-linked structure. Resin (for example, refer to Patent Document 3), etherified diphenol, dicarboxylic acid component containing specific dicarboxylic acid, and trivalent or higher monomer component containing trimellitic anhydride are reacted to form a crosslinked structure. The resulting cross-linked polyester resin (see, for example, Patent Document 4) is known, but the low-temperature fixability is not always good.

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 and Tg are high (for example, see Patent Document 5) 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 6 and 7). However, 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 an alcohol component, and a non-linear cross-linked polyester resin (see, for example, Patent Document 8) composed of rosin, an unsaturated dicarboxylic acid and another dicarboxylic acid as an acid component, a specific alcohol component or Examples using acid components (see, for example, Patent Documents 9, 10, and 11), examples using block polymers (see, for example, Patent Document 12), 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-1-155362 JP-A-57-109825 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.

On the other hand, the polyester resin itself has a strong negative chargeability, and when used as a positively chargeable toner, a positively chargeable charge control agent is essential. Conventionally, nigrosine dyes, quaternary ammonium salt compounds, triphenylmethane dyes, and the like have been used as positively chargeable charge control agents. Among them, quaternary ammonium salt compounds are often white and light in color, and are versatile. (For example, see Patent Document 14)
JP-A-60-169857

  As described above, it has excellent fixing characteristics such as anti-offset property and low-temperature fixing property. In addition, it has excellent various characteristics such as electrical characteristics such as chargeability, storage stability of toner, and pulverization property during toner production. Various proposals have been made to obtain a toner capable of forming a good image over a long period of time. However, there has not yet been found a positively chargeable magnetic toner that can form a binder resin without using bisphenol A so as not to adversely affect the environment. It is.

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

  Another object of the present invention is to provide a positively chargeable magnetic toner using an inexpensive polyester resin for toner as a binder resin.

  Another object of the present invention is to provide a positively chargeable magnetic toner capable of forming an image having the same density as that of the prior art by using a small amount.

  The present invention relates to a positively chargeable magnetic toner containing at least a binder resin, a positively chargeable charge control agent, and a magnetic material. The binder resin has an acid component of (1) disproportionated rosin and (2). The terephthalic acid and / or isophthalic acid and the alcohol component are composed of (3) a glycidyl ester of a tertiary fatty acid and (4) an aliphatic diol having 2 to 10 carbon atoms, the acid value is smaller than 10 mgKOH / g, and the hydroxyl value The present invention relates to a positively chargeable magnetic toner, which is a linear polyester resin having an A of 20 mgKOH / g or less and the positively chargeable charge control agent is a quaternary ammonium salt compound or a quaternary ammonium salt-containing resin.

The present invention also relates to the above positively chargeable magnetic 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 above positively chargeable magnetic toner, wherein the volume average particle size of the quaternary ammonium salt compound or the quaternary ammonium salt-containing resin is 0.5 to 40 μm.

The present invention also relates to the above positively chargeable magnetic toner, wherein the quaternary ammonium salt compound or the quaternary ammonium salt-containing resin has a BET specific surface area of 1 to 10 m ² / g.

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

  By using this linear polyester resin, the same or higher anti-offset property, low-temperature fixing property, sharp melt property, blocking resistance, charging property, and the like, without using bisphenol A or a bisphenol A derivative, A positively chargeable magnetic toner having characteristics such as grindability and transparency can be obtained. As a result, the storage stability of the toner classified product is improved, and a good developed image can be formed over a long period from the beginning of development without causing a decrease in fluidity of the toner during development and blocking of the toner.

  Furthermore, since bisphenol A or a derivative thereof is not used in the present invention, a linear polyester resin can be manufactured at a low cost, and the true density of the resin is higher than that using bisphenol A or a derivative thereof as an alcohol component. Therefore, if the positively chargeable magnetic 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 in the positively chargeable magnetic 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, and has an acid value of less than 10 mgKOH / g and a hydroxyl value of 20 mgKOH / g or less. It is necessary. And by this composition, it becomes possible to use it as positively charged by regulating the acid value and hydroxyl value.

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. Usually, the rosin is converted into a Pd carbon catalyst or the like. A method of saponifying the reaction product by reacting in the presence of a disproportionation catalyst under conditions of 250 to 300 ° C., 5 to 15 kg / cm ² , and 2 to 6 hours may be mentioned.
In addition, gum rosin, tall oil rosin, etc. that are usually available are abietic acid containing a conjugated double bond and are very easily oxidized, so they should be disproportionated for stabilization so as not to be discolored or altered by air oxidation. Is preferred. 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 0.5. More preferably, it is 0.2-0.3. 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 .5, the offset resistance tends to deteriorate and the image density tends to decrease.

  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. Examples of 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 0.10-0.15. 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 1.1, particularly preferably 0.95 to 1.05.

The linear polyester resin used in the present invention having the above structure needs to have an acid value of less than 10 mgKOH / g and a hydroxyl value of 20 mgKOH / g or less, preferably 15 mgKOH / g or less.
Further, when the acid value is 10 mgKOH / g or more, the positive chargeability of the toner is reduced, and the image density is lowered, or the fogging of the image and the in-machine scattering are increased. Further, since the hydrophilicity is further increased, the image density is lowered particularly in a high humidity environment. In the production examples of the linear polyester resin of the present invention, the acid value is 2.1 to 8.2 mgKOH / g. It is important that the polyester resin is suppressed to 10 mgKOH / g or less.
Further, similarly, when the hydroxyl value exceeds 20 mgKOH / g, the hydrophilicity increases, so that the image density is lowered particularly in a high humidity environment. In the production examples of the linear polyester resin of the present invention, the hydroxyl value was determined in the range of 3 to 18 mg KOH / g, and good results were obtained. It is important that is suppressed to 20 mgKOH / g or less.

  The linear polyester resin used in the present invention has a softening temperature of 115 to 150 ° C., preferably 120 to 145 ° C., and a tetrahydrofuran (THF) -soluble number average molecular weight of 1,000 to 6,000, preferably 2. , 4,000 to 4,000 is desirable. 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 decreases, the offset resistance of the toner tends to decrease, and when the number average molecular weight increases, the fixability tends to decrease.

The linear polyester resin used in the positively chargeable magnetic 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 present invention is prepared by a known and commonly used production method using the predetermined acid component and alcohol component as raw materials, and any of transesterification or direct esterification can be applied as the reaction method. Is possible. 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 production method of the linear polyester resin used in the present invention, a direct esterification method at normal pressure is mentioned as one of the preferred methods during the above various reactions. 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 for the positively charged magnetic 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.

  The positively chargeable charge control agent used in the positively chargeable magnetic toner of the present invention is preferably a quaternary ammonium salt compound. Examples of the quaternary ammonium salt compound that can be used in the present invention include a salt-forming compound composed of quaternary ammonium and an organic sulfonic acid or molybdic acid. As the organic sulfonic acid, naphthol sulfonic acid is preferably used, and naphthol monosulfonic acid is more preferably used.

  Specific quaternary ammonium salt compounds include tributylbenzylammonium-1-hydroxy-4-naphthalenesulfonate, tributylbenzylammonium-2-hydroxy-8-naphthalenesulfonate, triethylbenzylammonium-1-hydroxy-4. -Naphthalenesulfonate, tripropylbenzylammonium-1-hydroxy-4-naphthalenesulfonate, tripropylbenzylammonium-2-hydroxy-6-naphthalenesulfonate, trihexylbenzylammonium-1-hydroxy-4-naphthalene Examples thereof include sulfonate, tetrabutylammonium-1-hydroxy-4-naphthalene sulfonate, tetraoctylammonium-1-hydroxy-4-naphthalene sulfonate, and the like.

In the present invention, a quaternary ammonium salt-containing resin containing a quaternary ammonium salt can also be used. Formula - _{[CH 2 -CH (C 6 H 5} ) a ] - _{[CH 2 -CH (COOC 4 H 9} ) ] _b - _{[CH 2 -C (CH 3) COOC} 2 H 4 N + CH 3 (C ₂ H _{5) 2] cCH 3 (C 6 H 4)} SO 3 - ( these are parts quaternary ammonium salt 3 to 35 parts by weight of styrene-acrylic portion is 97 to 65 parts by weight, whereby a, b , C is determined), and a styrene / acrylic polymer copolymerized with a styrene / acrylic resin using a quaternary ammonium salt as a functional group.

  Specifically, poly (diallyldimethyl) is a salt of butyl acrylate, N, N-diethyl-N-methyl-2- (methacryloyloxy) ethylammonium = p-toluenesulfonate / styrene copolymer, benzalkonium chloride. Ammonium chloride).

  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 good 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 size is larger than 40 μm, the charge control agent cannot be held in the binder resin and falls off from the resin during pulverization. On the other hand, when a material having a volume average particle size smaller than 0.5 μm is used, the particles are easily aggregated, and dispersion in the binder resin becomes difficult. As described above, the above range is the optimum range of the particle size distribution for good dispersion.

In the present invention, not only the particle size distribution but also the numerical value of the BET specific surface area are important for obtaining good quality of the positively chargeable magnetic toner. A BET specific surface area favorable as a charge control agent is 1 to 10 m ² / g, preferably 1.5 to 8 m ² / g. When the specific surface area is smaller than 1 m ² / g, it is difficult to disperse the charge control agent in the binder resin, and the dispersion of the charge control agent in the toner becomes worse. 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 toner larger than 10 m ² / g is used, since the specific surface area is too large, the toner is excessively charged, the charge amount increases, and the image density may decrease. Thus, it is important to satisfy the specific range in both the particle size distribution and the BET specific surface area.

  The BET specific surface area of the charge control agent in the present invention was determined by a one-point BET method using Flowsorb II 2300 manufactured by Shimadzu Corporation-Micromeritics. Specifically, nitrogen gas was used as an adsorption gas and helium gas was used as a carrier gas in a gas adsorption method (flow method), and a detected desorption peak was obtained by TCD (thermal conductivity detector) to obtain a specific surface area. The gas in the initial state where the gas flows out at this time is (nitrogen: helium = 3: 7).

  The addition amount of the quaternary ammonium salt compound is usually 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, more preferably 0.8 to 3 parts by weight with respect to 100 parts by weight of the binder resin. is there. In the case of a quaternary ammonium salt-containing resin, the amount is usually 0.5 to 20 parts by weight, preferably 1.0 to 8.0 parts by weight with respect to 100 parts by weight of the binder resin.

  As a magnetic material that can be used in the positively chargeable magnetic toner of the present invention, a conventionally known magnetic material can be used. For example, iron oxide such as magnetite, maghemite, and ferrite, or a bivalent metal and iron oxide. And compounds such as iron, cobalt, nickel or aluminum, cobalt, copper, lead, magnesium, tin, zinc, antimony, beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, Examples thereof include powders of metal alloys such as vanadium and mixtures thereof. Among these, iron oxide or iron compounds such as divalent metals and iron oxide are preferable from the viewpoint of magnetic properties, coloring power, and raw material cost, and among these, magnetite is particularly preferable. As for the magnetite, any of various crystal forms such as a sphere, a hexahedron, and an octahedron can be used.

Among the above, the magnetic material used in the present invention preferably has a specific surface area of 4 to 8 m ² / g by the BET method. If a magnetic material having a specific surface area of more than 8 m ² / g according to the BET method is used, fogging tends to increase, and toner scattering tends to increase, resulting in deterioration of the quality of the copied image. Furthermore, black streaks, which are noises in the image due to charge leakage, occur and in-flight scattering occurs. This is because when the specific surface area of the magnetic material exceeds 8 m ² / g, it is difficult to uniformly disperse the toner in the toner base particles, which tends to cause a poor dispersion, thereby causing uneven distribution of the magnetic material in the toner base particles. This is because the resistance value of the particles varies and it becomes impossible to maintain a uniform and stable charge. In addition, the compounding property of the magnetic substance in the toner particles is also impaired, resulting in a difference in the content of the magnetic substance in the toner base particles and the classified fine powder, and it is difficult to recycle the classified fine powder and use it as a raw material during kneading. Become. On the other hand, when a material having a specific surface area smaller than 4 m ² / g is used, it is difficult for the magnetic particles to sufficiently color the toner base particles, and a desired image density as a toner cannot be obtained.

  These magnetic materials have an average particle diameter of 0.05 to 2.0 μm, preferably about 0.1 to 0.5 μm, and the amount contained in the magnetic toner is based on 100 parts by weight of the binder resin. It is 5-200 weight part, Preferably it is 10-150 weight part, More preferably, it is 60-100 weight part.

  Further, if necessary, it can be used in combination with a magnetic substance, and it can be used by adding inorganic / organic dyes / pigments conventionally known as colorants. For example, carbon black, aniline black, acetylene black Naphthol Yellow, Hansa Yellow, Rhodamun Lake, Alizarin Lake, Bengala, Phthalocyanine Blue, Indanthrene Blue and the like can be used.

The positively chargeable magnetic 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 positively chargeable magnetic 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. In addition, fine powders of fluorine-containing polymers such as polyvinylidene fluoride are preferable from the viewpoints of fluidity, abrasiveness, charge stability, and the like.

  In the positively chargeable magnetic toner of the present invention, it is preferable to contain hydrophobized silica, silicon aluminum cooxide, and silicon titanium cooxide fine powder as external additives. 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 positively chargeable magnetic 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 toner particle size distribution can be measured using, for example, a Coulter counter.

  The toner particles constituting the positively chargeable magnetic 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 together with an external additive as required using a mixer such as a Henschel mixer to obtain the positively chargeable magnetic toner of the present invention.

  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

Resin production example 1
Polyester resin raw material alcohol component neopentyl glycol 82.1 mol%, neodecanoic acid glycidyl ester 11.2 mol%, disproportionated rosin 18.2 mol% as 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 the 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 5 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 2-5
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, D, and E. The characteristic values of the obtained polyester resin are shown in Table 1.

Resin production example 6
Polyester resin raw material alcohol component of ethylene glycol 82.2 mol%, neodecanoic acid glycidyl ester 9.1 mol%, disproportionated rosin 21.4 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, 78.6 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 5 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 E 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
Polyester resin raw material alcohol component 83.6 mol% of bisphenol A ethylene oxide 2 mol adduct, neodecanoic acid glycidyl ester 10.3 mol%, disproportionated rosin 19.8 mol% as raw acid component, stirring device, heating A stainless steel reaction vessel equipped with an apparatus, a thermometer, a fractionator, and a nitrogen gas introduction tube was charged, and the temperature was raised to 160 ° C. with stirring to melt the contents. After melting, 80.2 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 5 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 I are shown in Table 2.

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

(Ingredient) (Blending amount)
Polyester resin A 53.0 parts by weight Magnetic substance (magnetite: specific surface area 7.3 m ² / g, shape: octahedron) 45.0 parts by weight Charge control agent (tributylbenzylammonium-1-hydroxy-4-naphthalene) Sulfonate average particle size 7.1 μm) 1.5 parts by weight / low molecular weight polypropylene (true density 0.905 g / cm ³ ) 0.5 part by weight After the above materials are uniformly mixed, kneaded, pulverized and classified Thus, positively chargeable toner particles having an average particle size of 10.3 μm were obtained. Next, to 100 parts of the toner particles, 0.3 part of silica fine powder treated with aminosilane and 0.5 part of calcium carbonate fine powder treated with aminosilane were added and mixed to obtain a positively chargeable magnetic toner.

The charge amount of the toner was measured to evaluate the chargeability, and the storage stability was also evaluated. The results are shown in Table 3.
Further, using this magnetic toner, a live-action test was performed using a commercially available copying machine (NP-2120 manufactured by Canon Inc.) having a structure of a hot-pressing roll as a fixing device, and image density (initial and after 5,000 sheets) Image density value), fog (initial and 5,000-image fog value), consumption, fixing property, and offset resistance were evaluated. Similarly, the results are shown in Table 3.

  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)
1 g of the above toner and 19 g of ferrite carrier (100 μm, non-coated) are weighed in a 50 cc plastic bottle, mixed at 1000 rpm for 30 minutes to prepare a developer having a toner concentration of 5% by weight, and a blow-off charge measuring device (Toshiba Chemical Co., Ltd.). The toner charge amount was measured. The measured value was converted into the charge amount per gram of toner, and this value was used as the charge amount of toner (μC / g). 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)
Image density was measured using a Macbeth photometer. A concentration of 1.35 or more is good.

(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)
Expressed as the weight of toner consumed per 1,000 sheets in an actual photograph with a document density of 6% (g / 1000 sheets).

(Fixability test and evaluation)
Rub the fixed image with an eraser (dragonfly pencil MONO),
[Image density after rubbing / Image density before rubbing] × 100 (%)
The value calculated in (5) was expressed as 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. The evaluation results were evaluated as “◯” when no paper stain occurred, “Δ” when paper stain occurred slightly but no problem in practical use, and “X” when paper contamination with some practical problem occurred.

Examples 2-9
A magnetic toner was obtained and evaluated in the same manner as in Example 1 except that the polyester resin and the charge control agent shown in Table 4 were used. For these magnetic toners, in the same manner as in Example 1, charge amount, storage stability, image density (value of image density after initial and 5,000 sheets), fog (initial and fog after 5,000 sheets). Value), consumption, fixability, and offset resistance. The results are shown in Table 3.

Example 10
Polyester resin A 49.5 parts by weight Magnetic substance (magnetite: specific surface area 7.3 m ² / g, shape: octahedron) 45.0 parts by weight Charge control agent (butyl acrylate, N, N-diethyl-N -Methyl-2- (methacryloyloxy) ethylammonium = p-toluenesulfonate / styrene copolymer; average particle size 18 μm) 5.0 parts by weight / low molecular weight polypropylene (true density 0.905 g / cm ³ ) 0.5 Part by weight The above materials were uniformly mixed, then kneaded, pulverized and classified to obtain positively chargeable toner particles having an average particle size of 10.3 μm. In the same manner as in Example 1, 0.3 parts of silica fine powder treated with aminosilane and 0.5 parts of calcium carbonate fine powder treated with aminosilane were added to and mixed with 100 parts of the toner particles, and positively charged magnetic toner. Got. For this magnetic toner, in the same manner as in Example 1, charge amount, storage stability, image density (image density value after initial and 5,000 sheets), fog (initial and fog value after 5,000 sheets) ), Consumption, fixability, and offset resistance were evaluated. The results are also shown in Table 3.

Comparative Examples 1-5
A magnetic toner was obtained and evaluated in the same manner as in Example 1 except that the polyester resin shown in Table 3 was used. For these magnetic toners, in the same manner as in Example 1, charge amount, storage stability, image density (value of image density after initial and 5,000 sheets), fog (initial and fog after 5,000 sheets). Value), consumption, fixability, and offset resistance. The results are also shown in Table 3.

  The positively chargeable magnetic 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 a positively chargeable magnetic toner containing at least a binder resin, a positively chargeable charge control agent, and a magnetic material, the binder resin has acid components such as (1) disproportionated rosin, (2) terephthalic acid, and / or Alternatively, the isophthalic acid or 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, the acid value is smaller than 10 mgKOH / g, and the hydroxyl value is 20 mgKOH / g. A positively chargeable magnetic toner which is a linear polyester resin as described below and wherein the positively chargeable charge control agent is a quaternary ammonium salt compound or a quaternary ammonium salt-containing resin. The positively chargeable magnetic toner according to claim 1, wherein a true density of the binder resin is 1.1 to 1.3 g / cm ³ .   The positively chargeable magnetic toner according to claim 1, wherein the volume average particle diameter of the quaternary ammonium salt compound or the quaternary ammonium salt-containing resin is 0.5 to 40 μm. The positively chargeable magnetic toner according to claim 1, wherein the quaternary ammonium salt compound or the quaternary ammonium salt-containing resin has a BET specific surface area of 1 to 10 m ² / g.