JP2009258344A - Magnetic single-component toner for electrostatic latent image development - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide magnetic single-component toner for electrostatic latent image development, which is excellent in durability characteristics, improved in fixing property even when a polyolefin resin having a cyclic structure is used for a binder resin. <P>SOLUTION: The magnetic single-component toner for electrostatic latent image development contains at least a binder resin and a magnetic powder, wherein the binder resin comprises a polyolefin resin having a cyclic structure and a styrene-acrylic resin having an acid number of 5 to 15 mgKOH/g, and a mass ratio of the polyolefin resin to the styrene-acrylic resin ranges from 90:10 to 30:70. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a magnetic one-component toner for developing an electrostatic latent image used in a developing process such as an electrophotographic method, an electrostatic recording method, and an electrostatic printing method employed in a copying machine, a laser printer, and the like.

  In general, in an electrophotographic method or an electrostatic recording method, it is formed by exposing a latent image carrier made of a photoconductive photosensitive member or a dielectric to a photosensitive member charged by corona charging with a laser, an LED or the like. The electrostatic latent image is visualized using a developer such as toner, or the electrostatic latent image is visualized by reversal development to obtain a high quality image. In general, the toner applied to these development methods is obtained by mixing a thermoplastic resin as a binder with a dye, a pigment as a charge control agent, a wax as a release agent, and a magnetic material, and kneading, pulverizing, and classifying the average. Toner particles having a particle diameter of 5 to 15 μm are used. Then, inorganic fine powders such as silica and titanium oxide, and inorganic metal fine powders are externally added to the toner particles for the purpose of imparting fluidity to the toner, controlling charging of the toner, and improving cleaning properties.

  By the way, as dry development methods in various electrostatic copying methods currently in practical use, there are two-component development methods using a carrier such as toner and iron powder, and a magnetic material containing a magnetic substance inside the toner without using a carrier. A one-component development system is known.

  The method using the two-component developer can provide a relatively stable and high-quality image in the initial stage. However, when used over a long period of time, carrier deterioration occurs, that is, spent phenomenon occurs. There are the common disadvantages that the imparting ability is lowered and a high-quality image cannot be obtained over a long period of time, and that the mixing ratio of the toner and the carrier is difficult to keep constant, so that the long-term durability is lacking.

  In order to avoid such drawbacks, various development methods using a one-component developer composed only of toner have been proposed, and among them, a magnetic one-component development method employing a magnetic toner is generally well known and utilized.

  On the other hand, in recent years, printers and copiers using an electrophotographic system have been required to have low power consumption due to recent demands for energy saving. Among the dry electrophotographic processes of printers and copiers, the fixing process consumes the most power. For this reason, in order to achieve the above energy saving, it is necessary to improve and improve the fixing process, which is one of the most important factors. That is, it is necessary to fix the toner image on the recording paper with less power, in other words, less power consumption and less heat.

  The fixability of the toner is compared with the conventional toner because the magnetic powder containing 35 to 60% by mass of the magnetic powder is added to the toner, particularly in the case of a magnetic one-component toner added with a magnetic material to impart magnetism to the toner. However, there is a problem that the fixing property is deteriorated.

  In response to the above-described demands or problems, in the conventional technology relating to toner, proposals have been made such as improving the molecular weight and molecular weight distribution of the binder resin. Specifically, attempts have been made to lower the fixing temperature by lowering the molecular weight of the binder resin. However, although the melting point is lowered by lowering the molecular weight, the melt viscosity is also lowered at the same time, which causes a problem that an offset phenomenon to the heat fixing roller occurs. Furthermore, in order to prevent this offset phenomenon, a method of widening the low molecular region and the high molecular region of the molecular weight distribution of the binder resin, or partially cross-linking a part of the high molecular region has been performed. However, in this method, the glass transition temperature of the resin has to be lowered in order to sufficiently provide the fixing property, and it is inevitable that the blocking property of the toner is deteriorated. Further, if the low molecular weight portion of the binder resin is increased, the toner itself becomes fragile, and there is a possibility that a defect will occur if the recording paper after fixing is rubbed.

Styrene-acrylic resins and polyester resins are generally used as the binder resin, which is the main component of the toner, but recently, olefin resins having a cyclic structure (cycloolefin resins) have been studied. ing. Olefin-based resin with a cyclic structure is colorless and transparent, good thermal properties (low temperature fixing and high speed fixing properties), non-polar good high temperature and high humidity environment stability, sharp molecular weight distribution, good Because it has various excellent properties such as pulverization (high productivity, sharp particle size distribution), low water absorption, no pollution, etc., it is expected as a binder resin to replace styrene-acrylic resins and polyester resins. ing.
Further, in the conventional styrene-acrylic resin, when the developer is stirred in the developing unit for a long time, the edge portion of the toner is pulverized due to friction with the carrier, which causes generation of fine powder. When fine powder was generated, it caused fogging, and at the same time, caused in-flight scattering. It is generally said that this is because the resin strength of styrene-acryl is weak.

On the other hand, a general polyolefin resin having a cyclic structure is characterized by its toughness and is quite resistant to friction with a carrier. That is, the stress resistance in the developing machine is superior to that of styrene-acrylic resin from the viewpoint of durability.
However, since a general polyolefin resin having a cyclic structure is a nonpolar resin having no polarity, the adhesive strength to paper is weak and the fixing strength is poor. That is, it has been pointed out that the fixing characteristics are not sufficient.

Therefore, various methods have been proposed for improving the fixing property of general polyolefin resins having a cyclic structure.
Conventionally, as a method for improving the fixing characteristics, a method of introducing a release agent such as a low molecular weight wax into the toner has been used. However, in this method, the toner particles are easily fused to each other or the toner is easily fused to the charging member constituting the developing device. There is a risk. Further, in this method, it is not easy to uniformly disperse and finely disperse the release agent in the binder resin at the time of toner production. It is easy to get worse. Further, since it is not easy to select a molding condition for improving the dispersibility, the moldability of the toner is not sufficient. The above problems are more likely to occur as the amount of release agent introduced increases. Therefore, it is difficult to improve the fixing characteristics only by introducing a release agent without deteriorating characteristics such as anti-fusing property. Note that moldability refers to the ease of manufacturing a toner with good dispersibility of raw materials.

  Patent Document 1 is characterized in that it contains at least a cycloolefin copolymer resin as a binder resin and contains 7 to 20% by mass of a wax added as a release agent in terms of the total mass of toner particles. Toner is disclosed. However, in this case, since the low molecular weight component (wax) is contained in an amount of 7 to 20% by mass with respect to the toner particle mass, the toner particles are fused to each other or the toner is fused to the charging member constituting the developing device. Since the toner adheres easily, the anti-fusing property of the toner tends to deteriorate. Further, in this method, since it is not easy to uniformly and finely disperse a large amount of low molecular weight components in the binder resin at the time of toner production, the moldability of the toner is not sufficient. When the dispersibility is low, the anti-fusing property tends to deteriorate.

  Patent Document 2 describes a toner for developing an electrostatic charge image, in which the binder resin contains an alicyclic olefin resin and a thermoplastic elastomer. However, the thermoplastic elastomer basically has no active group capable of adhering to the recording paper. In addition, there is no clear description regarding this point.

  Further, in Patent Document 3, the binder resin is a polyolefin resin having a cyclic structure, a polyester resin, an epoxy resin, a polyolefin resin, a vinyl acetate resin, a vinyl acetate copolymer resin, a styrene-acrylic resin, and others. A toner for developing an electrostatic charge image with a heating roller fixed type composed of at least one selected from the above acrylic resins is described. However, there is no description of the acid value that greatly contributes to fixing characteristics, and it is unclear what kind of styrene-acrylic resin it is.

  In Patent Document 4, the binder resin includes at least a polyolefin resin having a cyclic structure, and the polyolefin resin has at least one functional group selected from a carboxyl group, a hydroxyl group, and an amino group. An electrostatic charge image developing toner is described. However, it is difficult to introduce the functional group into the polyolefin resin having the cyclic structure. That is, there are roughly two methods for introducing this carboxyl group into the resin. One is to oxidize an alkyl group such as a methyl group at the end of the resin by a melted air oxidation method to form a carboxyl group. However, in this method, in the case of a polyolefin resin having a cyclic structure synthesized by a metallocene catalyst, it is difficult to introduce many carboxyl groups because there is almost no branching. In another method, a peroxide is added to the resin, and maleic anhydride is reacted with a portion of the generated radical. In the case of this method, it is theoretically possible to introduce many carboxyl groups onto the resin. However, when the introduction ratio increases, the resin turns yellow and the transparency deteriorates.

JP 2003-114546 A JP 2005-292362 A Japanese Patent Laid-Open No. 9-101631 JP 2000-284528 A

  An object of the present invention is to provide a magnetic one-component toner for developing an electrostatic latent image, which can improve fixability even when a polyolefin resin having a cyclic structure is used as a binder resin, and has excellent durability characteristics. .

  As a result of intensive studies to solve the above-mentioned problems, the present inventor made a binder resin a polyolefin resin having a cyclic structure as a main resin, and a styrene-acrylic resin having a predetermined acid value. By configuring with a predetermined mass ratio, the inventors have found a new fact that it is possible to obtain a magnetic one-component toner for developing an electrostatic latent image that can maintain stable image quality over a long period of time and has excellent fixability. It came to be completed.

That is, the magnetic one-component toner for developing an electrostatic latent image of the present invention has the following characteristics.
(1) A magnetic one-component toner for electrostatic latent image development containing at least a binder resin and magnetic powder, wherein the binder resin is a polyolefin resin having a cyclic structure and an acid value of 5 to 15 mgKOH / g. A magnetic one-component toner for developing an electrostatic latent image, comprising a styrene-acrylic resin, wherein a mass ratio of the polyolefin resin to the styrene-acrylic resin is 90:10 to 30:70.
(2) A magnetic one-component toner for developing an electrostatic latent image containing at least a binder resin and magnetic powder, wherein the binder resin comprises a polyolefin resin having a cyclic structure and a styrene-acrylic resin, and the styrene The magnetic monocomponent toner for developing an electrostatic latent image, wherein the acrylic resin has an acid value of 5 to 15 mg KOH / g and a ratio to the total toner amount of 5 to 49% by mass.
(3) The polyolefin resin having the cyclic structure comprises a copolymer of an acyclic olefin and an alicyclic hydrocarbon having at least one double bond (1) or (2) A magnetic one-component toner for developing electrostatic latent images.
(4) The magnetic one-component toner for developing an electrostatic latent image according to any one of (1) to (3) further contains a colorant, a charge control agent, a wax, and an external additive. Magnetic one-component toner for developing an electrostatic latent image.

  According to the magnetic one-component toner for developing an electrostatic latent image of the present invention, the binder resin is a polyolefin resin having a cyclic structure as a main resin, and a styrene-acrylic resin having a predetermined acid value is a predetermined resin. By being configured with the mass ratio, it is possible to expect an excellent effect that a stable image characteristic can be obtained over a long period of time and a toner having excellent fixability can be obtained.

The magnetic one-component toner for developing an electrostatic image according to the present invention will be described in detail below. In the magnetic one-component toner for developing electrostatic images according to the present invention, the binder resin constituting the toner is mainly a polyolefin resin having a cyclic structure, and a styrene-acid having an acid value of 5 to 15 mgKOH / g. It consists of a resin with an acrylic resin added. And mass ratio of the said polyolefin resin and the said styrene-acrylic resin is 90: 10-30: 70.
In the toner of the present invention, the binder resin constituting the toner is a polyolefin resin having a cyclic structure as a main resin, and a resin obtained by adding a styrene-acrylic resin having an acid value of 5 to 15 mg KOH / g to the resin. The ratio of the styrene-acrylic resin to the total amount of toner is 5 to 49% by mass.

A general polyolefin resin having a cyclic structure is characterized by its toughness, is quite strong against friction with a carrier, and is excellent in stress resistance in a developing machine.
On the other hand, a styrene-acrylic resin having an acid value of 5 to 15 mgKOH / g has good fixability. Therefore, by adding the styrene-acrylic resin to the polyolefin resin as a binder resin constituting the toner so that the mass ratio of the polyolefin resin and the styrene-acrylic resin is 90:10 to 30:70, A toner having excellent durability and excellent fixing characteristics can be obtained. Further, in the configuration of the binder resin, the same effect as described above can be obtained when the ratio of the styrene-acrylic resin having an acid value of 5 to 15 mgKOH / g to the total toner amount is 5 to 49% by mass.

  As described above, the binding tree has a mass ratio of the polyolefin resin to the styrene-acrylic resin of 90:10 to 30:70, preferably 70:30 to 30:70, and more preferably 70: 30-35: 65. When the ratio of the styrene-acrylic resin is less than 10% by mass with respect to the binder resin, a sufficient effect on the fixing property, which is the greatest merit of the styrene-acrylic resin, cannot be obtained. On the other hand, if it exceeds 70% by mass, the acid value of the entire toner increases, causing a decrease in image density or fogging due to poor charging, particularly in a high temperature and high humidity environment. At the same time, since the proportion of the polyolefin resin having a cyclic structure in the toner decreases, the durability is inferior.

  Further, as described above, the binding tree has a ratio of the styrene-acrylic resin to the total toner amount of 5 to 49% by mass, preferably 10 to 40% by mass, and more preferably 15 to 35% by mass. Good. When the ratio of the styrene-acrylic resin to the total amount of toner is less than 5% by mass, a sufficient effect on the fixing property, which is the greatest merit of the styrene-acrylic resin, cannot be obtained. On the other hand, if it exceeds 49% by mass, the acid value of the entire toner increases, causing a decrease in image density or fogging due to poor charging, particularly in a high temperature and high humidity environment. At the same time, since the proportion of the polyolefin resin having a cyclic structure in the toner decreases, the durability is inferior.

As described above, the acid value of the styrene-acrylic resin is 5 to 15 mgKOH / g. If it is less than 5 mgKOH / g, no effect is observed on the fixability. On the other hand, when the acid value exceeds 15 mgKOH / g, the hydrophilicity increases, and this causes a decrease in image density or a fog phenomenon due to charging failure particularly in a high temperature and high humidity environment. When the toner of the present invention is used as a positively charged toner, the acid value is preferably 5 to 10 mgKOH / g because negative chargeability increases as the acid value increases.
In addition, in this invention, an acid value means the mg number of potassium hydroxide required in order to neutralize the carboxyl group contained in 1g of resin.

The acid value can be measured as follows. That is, 2-10 g of resin samples are weighed into a 200-300 mL Erlenmeyer flask. About 50 mL of a mixed solvent of methanol: toluene = 30: 70 is added to the weighed resin sample to dissolve the resin. At this time, if the solubility is poor, a small amount of acetone may be added. Titrate with a pre-rated N / 10 potassium hydroxide-alcohol solution using a mixed indicator of 0.1% bromthymol blue and phenol red. An acid value is calculated | required by following formula (1) from the consumption of this potassium hydroxide-alcohol solution. However, N is the titer (factor) of (N / 10) KOH.

(toner)
The toner of the present invention is a magnetic toner containing at least a binder resin and magnetic powder, and a colorant, a charge control agent, a wax, an external additive, and the like can be appropriately used.
As described above, a polyolefin resin having a cyclic structure is used as a main resin for the binder resin used in the toner of the present invention. Examples of the polyolefin resin having a cyclic structure include a cyclic polyolefin copolymer (hereinafter referred to as COC). Examples of the COC include a lower alkene having 2 to 12 carbon atoms (acyclic olefin) and norbornene, Examples thereof include a copolymer with an alicyclic compound having 3 to 17 carbon atoms and having at least one double bond such as tetracyclohexene, dicyclopentadiene, and cyclohexene.

Such COC can be obtained, for example, by a polymerization method using a metallocene catalyst or a Ziegler catalyst. Specifically, one or more monomers of an acyclic olefin and one or more monomers of a cycloolefin are -78 to 150 ° C, preferably 20 to 80 ° C, pressure 0.01 to 64 bar, aluminoxane, etc. In the presence of a catalyst comprising at least one metallocene comprising, for example, zirconium or hafnilum.
More specifically, TOPAS TB, TM, 9506F04, etc. manufactured by Ticona Corporation can be exemplified.

  Examples of the styrene-acrylic resin include styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-n-butyl acrylate copolymer, styrene-isobutyl acrylate copolymer, styrene-acrylic acid. n-octyl copolymer, styrene-dodecyl acrylate copolymer, styrene-acrylic acid 2-chloro-ethyl copolymer, styrene-phenyl acrylate copolymer, styrene-α-methyl chloroacrylate copolymer, styrene And methyl-methacrylate copolymer, styrene-ethyl methacrylate copolymer, and styrene-butyl methacrylate copolymer. These copolymers are used alone or in admixture of two or more.

These can be obtained by copolymerizing a styrene monomer and an acrylic monomer. Specific examples of the monomer include styrene monomers such as styrene, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene and other alkyl styrenes, halogenated styrene, etc., and acrylic monomers as Acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, phenyl acrylate, methyl methacrylate , Ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide and the like.
The styrene-acrylic resin of the present invention can be obtained by subjecting the above monomers to emulsion polymerization, suspension polymerization, solution polymerization or bulk polymerization. Further, the composition and composition ratio of the polymer of the high molecular weight component and the polymer of the low molecular weight component may be different. In particular, a resin obtained by suspension polymerization is preferred.

In the binder resin, the glass transition point (Tg) is preferably set to a value in the range of 55 to 70 ° C. When the glass transition point of the binder resin is less than 55 ° C., the obtained toners are fused with each other, and the storage stability tends to be lowered. On the other hand, when the glass transition point of the binder resin exceeds 70 ° C., the fixability of the toner tends to be poor.
In addition, Tg demonstrated here can be calculated | required with the following measuring methods. Specifically, as a differential scanning calorimeter (DSC) for measuring Tg, DSC6200 manufactured by SII (SII) Technology Co., Ltd. is used. First, about 10 mg of a sample is placed in an aluminum sample container, which is placed on a holder unit. Set in an electric furnace. Then, after heating from 30 ° C. to 170 ° C. at a temperature rising rate of 10 ° C./min, the sample is cooled to 30 ° C. and heated again to 170 ° C. at a temperature rising rate of 10 ° C./min to perform DSC measurement.
Tg is obtained by calculating from the contact point between the tangent line of the endothermic curve near the Tg and the base line using the analysis system in DSC6200.

(Magnetic powder)
In the toner of the present invention, a known magnetic powder is used as a magnetic toner dispersed in the toner. As magnetic powder, ferritic metals such as ferrite and magnetite, cobalt, nickel and other metals exhibiting ferromagnetism, alloys or compounds containing these elements, or containing no ferromagnetic elements, but subjected to appropriate heat treatment An alloy that exhibits ferromagnetism or chromium dioxide can be used. These magnetic powders are uniformly dispersed in the toner binder in the form of fine powders having an average particle size in the range of 0.1 to 1 μm, preferably 0.1 to 0.5 μm. The magnetic powder may be a single substance or a surface treated with a surface treatment agent such as a titanium coupling agent or a silane coupling agent. Further, the blending amount of the magnetic powder is preferably 20 to 200 parts by mass, more preferably 50 to 150 parts by mass with respect to 100 parts by mass of the binder resin.
By using the magnetic toner of the present invention, it is possible to prevent a reduction in the fixing strength of the toner, which is likely to occur with the magnetic toner, and it is possible to prevent the generation of fine powder that is easily separated from the toner due to stress in the developing means. And offset resistance can be maintained.

(Coloring agent)
In the toner of the present invention, a pigment such as carbon black or a dye such as acid violet can be dispersed in the binder resin as a colorant in order to adjust the color tone, as in the known toner. Such a colorant is usually blended in an amount of 1 to 10 parts by mass per 100 parts by mass of the binder resin.

(Charge control agent)
In the toner of the present invention, the charge level and charge rising characteristics (indicator of whether to charge to a constant charge level in a short time) are remarkably improved, and from the viewpoint of obtaining excellent durability and stability characteristics, etc. It is preferable to add a control agent.
Here, the kind of the charge control agent to be added is not particularly limited, and examples thereof include nigrosine, quaternary ammonium salt compounds, and resin-type charge control agents in which an amine compound is bonded to a resin. It is preferable to use a charge control agent exhibiting positive chargeability. Further, these charge control agents may be used in combination.

  For example, specifically, pyridazine, pyrimidine, pyrazine, orthooxazine, metaoxazine, paraoxazine, orthothiazine, metathiazine, parathiazine, 1,2,3-triazine, 1,2,4-triazine, 1,3 as azine compounds , 5-triazine, 1,2,4-oxadiazine, 1,3,4-oxadiazine, 1,2,6-oxadiazine, 1,3,4-thiadiazine, 1,3,5-thiadiazine, 1,2,3 4-tetrazine, 1,2,4,5-tetrazine, 1,2,3,5-tetrazine, 1,2,4,6-oxatriazine, 1,3,4,5-oxatriazine, phthalazine, quinazoline , Azin Fast Red FC, Azin Fast Red 12BK, Azinba as a direct dye consisting of quinoxaline and azine compounds Oret BO, Azine Brown 3G, Azin Light Brown GR, Azin Dark Green BH / C, Azin Deep Black EW and Azin Deep Black 3RL, Nigrosine as Nigrosine Compound, Nigrosine Salt, Nigrosine Derivative, Nigrosine Compound as Acid Dye One or more of nigrosine BK, nigrosine NB, nigrosine Z, metal salts of naphthenic acid or higher fatty acids, alkoxylated amines, alkylamides, benzylmethylhexyldecylammonium as quaternary ammonium salts, decyltrimethylammonium chloride, etc. Can be mentioned. In particular, the nigrosine compound is most suitable for the use of a positively chargeable toner from the viewpoint of obtaining quicker start-up properties.

  In addition, a resin or oligomer having a quaternary ammonium salt, a resin or oligomer having a carboxylate, a resin or oligomer having a carboxyl group, and the like, more specifically, a polystyrene resin having a quaternary ammonium salt, 4 Acrylic resin having quaternary ammonium salt, styrene-acrylic resin having quaternary ammonium salt, polyester resin having quaternary ammonium salt, polystyrene resin having carboxylate, acrylic resin having carboxylate, carvone Styrene-acrylic resin having acid salt, polyester resin having carboxylate salt, polystyrene resin having carboxyl group, acrylic resin having carboxyl group, styrene-acrylic resin having carboxyl group, poly having carboxyl group One or more of such ester resins.

  In particular, a styrene-acrylic resin (styrene-acrylic copolymer) having a quaternary ammonium salt, carboxylate or carboxyl group as a functional group can easily adjust the charge amount to a value within a desired range. It is optimal from the point of view. Moreover, as a preferable acrylic resin in the above-mentioned styrene-acrylic resin or acrylic resin itself, (meth) acrylic acid alkyl ester includes methyl acrylate, ethyl acrylate, n-propyl acrylate, iso-propyl acrylate. N-butyl acrylate, iso-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, iso-butyl methacrylate, and the like.

  Furthermore, as the quaternary ammonium salt compound, a unit derived from a dialkylaminoalkyl (meth) acrylate through a quaternization step is used. Examples of the derived dialkylaminoalkyl (meth) acrylate include di (amino) ethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dipropylaminoethyl (meth) acrylate, dibutylaminoethyl (meth) acrylate and the like ( Lower alkyl) aminoethyl (meth) acrylate; dimethylmethacrylamide, dimethylaminopropylmethacrylamide are preferred. Further, hydroxy group-containing polymerizable monomers such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and N-methylol (meth) acrylamide can be used in combination during polymerization.

  In addition, examples of negative chargeability include organic metal complexes and chelate compounds, such as monoazo metal complexes, acetylacetone metal complexes, aromatic hydroxycarboxylic acids, and aromatic dicarboxylic acid metal complexes. Other examples include aromatic hydroxycarboxylic acids, aromatic mono- and polycarboxylic acids and their metal salts, anhydrides, esters, and phenol derivatives such as bisphenol.

  Further, when the total amount of the toner is 100% by mass, the addition amount of the charge control agent is preferably set to a value within the range of 1.5 to 15% by mass. When the addition amount of the charge control agent is less than 1.5% by mass, it becomes difficult to stably impart charging characteristics to the toner, and the image density tends to be low and the durability tends to be low. In addition, poor dispersion tends to occur, so-called fogging tends to occur, and photoconductor contamination tends to increase. On the other hand, if the amount of the charge control agent added exceeds 15% by mass, the environment resistance, particularly charging failure and image failure under high temperature and high humidity, tends to cause defects such as photoconductor contamination. Therefore, from the viewpoint of a better balance between the charge control function and the durability of the toner, the addition amount of the charge control agent is more preferably set to a value in the range of 2.0 to 8.0 mass%. More preferably, the value is within the range of 3.0 to 7.0% by mass.

(wax)
In the toner of the present invention, a wax may be used as a fixing aid and a hot offset improver. The wax is not particularly limited. For example, it is made by Fischer-Tropsch method from olefin wax such as synthetic polyethylene wax and synthetic polypropylene wax, plant wax such as carnauba wax, rice wax and candelilla wax, mineral wax such as montan wax, coal and natural gas. And petroleum-based waxes such as Fischer-Tropsch wax, paraffin wax, and microcrystalline wax, ester waxes, and Teflon (registered trademark) waxes. These waxes may be used in combination.

  When the melting point Wmp in the DSC of the wax is set, it is preferable that 70 ≦ Wmp ≦ 120 is satisfied. If it is less than 70, the apparent glass transition temperature of the toner is greatly lowered, and the blocking property is deteriorated. If it exceeds 120, the low melt viscosity of the resin becomes dull, resulting in poor fixability.

  The amount of wax added is preferably in the range of 1 to 5% by mass. If it is less than 1% by mass, the effect of reducing the melting of the wax into the toner is diminished, resulting in poor fixing. If the amount exceeds 5% by mass, the probability that the wax in the toner is present alone increases, and the photosensitive member is contaminated, that is, drum filming occurs, and the charge amount distribution is greatly disturbed. Image defects such as image density reduction and fogging are caused.

(External additive)
In order to maintain the fluidity and storage stability of the toner, it is preferable to use fine particles such as colloidal silica, hydrophobic silica, alumina and titanium oxide (usually having an average particle size of 1.0 μm or less) as an external additive.
The external additive is used to improve fluidity, storage stability, cleaning properties, etc. by surface treatment of the toner, and is generally 0.2 to 10 per 100 parts by mass of the toner. Used in an amount of 0.0 parts by weight. The external addition of these fine particles can also be performed by dry mixing with magnetic toner. In this case, a Henschel mixer or a Nauter mixer is used so that the fine particles are not embedded in the toner. It is good.

  Hereinafter, the magnetic monocomponent toner for developing an electrostatic latent image of the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[Example 1]
First, the manufacture example of a styrene-acrylic resin is shown below.
A monomer solution consisting of 70 parts by mass of styrene and 30 parts by mass of butyl acrylate is placed in a solution containing 6 parts by mass of AIBN as a polymerization initiator and 200 parts by mass of toluene as a solvent (having a condenser and refluxing toluene). After dropwise addition over 3 hours, polymerization was carried out for 12 hours while maintaining the temperature at 60 ° C., and then toluene was removed by distillation under reduced pressure. Further, trimellitic anhydride was added at 180 ° C. so that the acid value was 9 mg KOH / g. It was added to the reaction system, heated to 210 ° C. at a rate of 10 ° C./hour and reacted to obtain a styrene-acrylic resin.

(toner)
The above-obtained styrene-acrylic resin, COC, magnetic powder, wax, and charge control agent were mixed in the proportions shown in Table 1 to prepare the toner of the present invention.
That is, 19 parts by mass of COC (manufactured by Ticona: TOPAS TB), 35 parts by mass of styrene-acrylic resin having an acid value of 9 mg KOH / g, 40 parts by mass of magnetic powder, 3 parts by mass of wax (manufactured by Sazol: Sazol Wax H1) 3 parts by mass of a quaternary ammonium salt (Orient Chemical Industries, Ltd .: Bontron P-51) as a positive charge control agent was mixed, the mixture was melt-kneaded with a twin screw extruder, cooled, and then hammer milled. Crushed at. The finely pulverized product in a mechanical pulverizer was classified by an airflow classifier to obtain a magnetic toner powder having a volume average particle size of 8.0 μm.
Henschel mixer with 1.0 part by mass of silica (manufactured by Nippon Aerosil Co., Ltd .: RA-200H) and 2 parts by mass of titanium oxide (manufactured by Titanium Industry Co., Ltd .: ST-100) with respect to 100 parts by mass of the magnetic toner powder. Was added to the surface of the magnetic toner powder to obtain a magnetic one-component positively charged developer.

[Examples 2 to 5, Comparative Examples 1 to 5]
Examples 2 to 5 and Comparative Examples 1 to 5 were produced in the same manner as in Example 1 except that the acid value of the styrene-acrylic resin and the mass ratio with COC were changed to the combinations shown in Table 1.

(Evaluation test and evaluation method)
Using the produced toners of Examples 1 to 5 and Comparative Examples 1 to 5 as a magnetic one-component developer, using an evaluation machine (FS-3830N) manufactured by Kyocera Mita Inc. equipped with an amorphous silicon (a-Si) photoreceptor, Image characteristics (image density, fog) and thermal characteristics (fixability) were evaluated. At the same time, the toner charge amount was also measured. These results are shown in Table 2.

Evaluation methods and evaluation criteria are as follows.
(1) Charge amount 4 parts by mass of the above magnetic toner and 100 parts by mass of ferrite carrier (FK-150, manufactured by Powdertech Co., Ltd.) are mixed, and the mixture is kept at room temperature and humidity (20 ° C., 65% RH) for 5 minutes. The amount of charge (μC / g) when frictionally charged was used. Specifically, after magnetic toner and ferrite carrier are mixed in a normal temperature and normal humidity environment, they are triboelectrically charged by stirring for 10 minutes in a ball mill. Then, the charge amount of 100 mg of the mixture of the magnetic toner and the ferrite carrier was measured using a charge amount measuring device [Q / M meter 210HS manufactured by TREK Co.]. Next, the charge amount μC / g per gram of toner was determined by removing the mass of the ferrite carrier.
(2) Image Density Using the above evaluation machine, an image evaluation pattern is printed at the initial stage in a normal temperature and humidity environment (20 ° C., 65% RH) to form an image, and the solid image is converted into a Macbeth reflection densitometer [Gretag Macbeth Co., Ltd. RD914] manufactured by the manufacturer. The results are shown in Table 2. Evaluation criteria were good when the image density was 1.20 or more.
(3) Fog The blank area of the initial image formed in (2) above was visually observed to check for the presence of earth fog. The evaluation criteria are as follows.
○: Good fogging.
Δ: Slight fogging occurs.
X: The fog is terrible.
(4) Fixing property The fixing temperature is set to 180 ° C., and after cooling for 10 minutes in a normal temperature and humidity environment (20 ° C., 65% RH) with the power off, the power is turned on and the solid image of the fixing pattern is continuously displayed. Five sheets were printed and a measurement image was obtained. This image was rubbed 10 times with a load of brass weight (1 kg) wrapped in cotton cloth. The image density before and after this operation was measured with a Macbeth reflection densitometer [RD914 manufactured by Gretag Macbeth Co., Ltd.], and the ratio of the density was obtained to determine the fixing property. The evaluation criteria are as follows.
○: Fixing rate is 95% or more.
Δ: The fixing rate is 90% or more and less than 95%.
X: Fixing rate is less than 90%.
(5) Charge amount, image density and fog in high temperature and high humidity environment 10 parts by mass of the toner and 100 parts by mass of ferrite carrier are mixed and left in a high temperature and high humidity environment (33 ° C., 85% RH) for 12 hours. The charge amount (μC / g) when frictionally charged for 5 minutes was measured using a charge amount measuring device [Q / M meter 210HS manufactured by TREK Co., Ltd.]. Next, the charge amount μC / g per gram of toner was determined by removing the mass of the ferrite carrier.
The evaluation machine FS-3830N was also allowed to stand for 12 hours in the same high-temperature and high-humidity environment to stabilize the state, and then an image evaluation pattern was printed in the same high-temperature and high-humidity environment to obtain an image. Then, as in (2) and (3) above, the solid image was measured using a Macbeth reflection densitometer [RD914 manufactured by Gretag Macbeth Co., Ltd.], and at the same time, the image characteristics were evaluated by visually observing the fog. It was. The evaluation criteria are the same as (2) and (3) for image density and fog, respectively.

As shown in Table 2, Examples 1 to 5 under the conditions within the scope of the present invention have improved fixability that could not be realized by COC alone in both a normal temperature and normal humidity environment and a high temperature and high humidity environment. And showed good results in image density and fog. Further, the developer has high durability utilizing “resin hardness” which is a characteristic of COC, and a good image density is maintained even during durability.
On the other hand, in Comparative Example 1, since the acid value of the styrene-acrylic resin used in combination was too low, the adhesiveness to paper as a toner was low, and the fixability in a normal temperature and humidity environment could not be satisfied. In Comparative Example 2, since the acid value of the styrene-acrylic resin used in combination was too high, the water absorption of the toner increased, resulting in poor charging. Particularly, the charge amount was low and the image density was lowered in a high temperature and high humidity environment. In Comparative Example 3, since the addition amount of the styrene-acrylic resin was small, the fixability could not be satisfied. Further, in Comparative Example 4, there was a problem in fixability due to the use of COC alone. In Comparative Example 5, since the amount of styrene-acrylic resin added was large, the fixing property was satisfactory, but since a large amount of styrene-acrylic resin having a relatively high acid value was added, there was a tendency for poor charging and fogging. Occurred.

Claims (4)

  A magnetic one-component toner for electrostatic latent image development containing at least a binder resin and magnetic powder, wherein the binder resin is a polyolefin resin having a cyclic structure and a styrene-acrylic acid having an acid value of 5 to 15 mgKOH / g. A magnetic one-component toner for developing an electrostatic latent image, comprising a resin, wherein a mass ratio of the polyolefin resin to the styrene-acrylic resin is 90:10 to 30:70.   A magnetic one-component toner for electrostatic latent image development containing at least a binder resin and magnetic powder, wherein the binder resin comprises a polyolefin resin having a cyclic structure and a styrene-acrylic resin, and the styrene-acrylic resin Is a magnetic one-component toner for developing an electrostatic latent image, characterized in that the acid value is 5 to 15 mg KOH / g and the ratio to the total toner amount is 5 to 49% by mass.   3. The electrostatic latent image according to claim 1, wherein the polyolefin resin having a cyclic structure is a copolymer of an acyclic olefin and an alicyclic hydrocarbon having at least one double bond. Magnetic one-component toner for image development.   The magnetic one-component toner for developing an electrostatic latent image according to any one of claims 1 to 3, further comprising a colorant, a charge control agent, a wax, and an external additive. Magnetic one component toner.