JP2012247629A - Toner for electrostatic charge image development - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner that is characterized in energy-saving, low cost, and long life in consideration of preserving global environment as an ultimate objective, in particular, a toner for electrostatic charge image development that contains a resin component that can be replaced with a non-petroleum-based compound for each color, provides sufficient image density even at low development potential and low transfer potential during printing, requires less amount of the toner, is less likely to be scraped off, prevents the occurrence of ground fogging in printed images, and experiences less change in the charge amount for a long period.SOLUTION: A toner for electrostatic charge image development contains at least a binder resin and an anti-static composition, uses a polyhydroxyalkanoate containing a crystal nucleus agent as the anti-static composition, and contains 5 to 70 mass% of the anti-static composition.

Description

  The present invention relates to an electrostatic charge image developing toner for forming an image in electrophotography, electrostatic recording method or the like. More particularly, the present invention relates to a positively charged electrostatic image developing toner containing a charge control resin.

  The electrophotographic method is widely used as one of image forming methods in copying machines, printers, facsimiles and the like. In general image formation by electrophotography, an electrostatic latent image is formed by irradiating a photoconductive insulator (photoconductor) uniformly charged with a charging blade, a charging brush, or the like with laser light or LED light. A developing step of forming an image by electrostatically adhering an electrostatic charge image developing toner (hereinafter simply referred to as toner) to the electrostatic latent image to form a toner image; A transfer step of transferring the image to a recording medium such as paper, and a fixing step of fixing the transferred toner image by radiating and fixing the toner image on the recording medium by contact with a heat medium or infrared irradiation.

  The toner used in the developing step needs to be uniformly and stably charged so as to adhere to the electrostatic latent image on the surface of the photoreceptor. As a toner charging method, it is common to use frictional charging by sliding with another member in advance, and the two-component development method using friction with carrier particles such as magnetic powder as the other member, A one-component developing system using a friction mechanism by a charging member such as a charging blade installed in a developing device is well known.

In recent years, not only high-speed printing and high image quality have been demanded, but also an apparatus that takes into account good economic efficiency and reduced environmental impact is desired, and sufficient image density can be achieved even at low development potential and low transfer potential. Thus, there is a demand for a long life developer that does not cause background fogging. Keeping the development potential and transfer potential low leads to energy savings in the device, and extending the life of the developer contributes to a reduction in the cost of copying and prolongs the renewal cycle of the developer member, thereby reducing the number of waste members. Leads to.
In addition, in order to achieve both economic efficiency and downsizing of the equipment, many full-color multifunction printers (MFPs) and printers that employ a non-magnetic one-component development system have been launched especially for personal and SOHO use. Has been. Even for such highly economical small-sized full-color printers, there is a high demand for image quality, and there is little fogging without being affected by changes in the installation environment for a long period from the initial use to the replacement of the toner cartridge, and toner consumption Therefore, it is desired that a stable image is output with little toner scattering in the apparatus.
Furthermore, in order to consider the future impact on the global environment in industrial products in general, it is used because it is formed based on carbon dioxide that originally existed in the atmosphere while reducing the use of petroleum resources. Even so, there is a demand for conversion to carbon neutral raw materials that do not increase the concentration of carbon dioxide in the atmosphere.

Conventionally, in order to obtain such a developer in black toner, various types of carbon black and charge control agents, internal additives, external additives, carriers in two-component development, etc. Thus, it has been attempted to stabilize the charge amount by appropriately controlling the electric resistance value of the toner by optimally selecting, combining and preparing the addition method.
However, in the case of each color other than black or transparent toner, the usable color materials are limited for the convenience of color reproduction. For example, carbon black exhibiting black or a dark charge control agent cannot be used as a method for stabilizing the charge. For this reason, in the toner other than black, the conventional black toner configuration cannot be used as a method for controlling the electric resistance value, and the charge amount of the toner particles is controlled within an appropriate range and stabilized with time. Has become a technical challenge.
In particular, in the non-magnetic one-component development system, excessively frictionally charged toner particles may be generated by the operation of an agitator provided to feed toner to the vicinity of the charging member while stirring the toner in the developing device. If toner particles with a high charge amount stay in the container, there is a unique phenomenon in which charging of newly supplied uncharged toner by the charging member is hindered. As a result, toner particles sent to the developing roller Charge amount tends to be uneven.
If the charge amount of the toner particles is not uniform, the number of toner particles that are outside the proper range of the toner charge amount required by the apparatus increases. Due to the presence of insufficiently charged toner, there is a problem that the toner is not held by the developing roller and overflows (toner drops) inside the printing apparatus, or the ground cover increases on the printing surface. Due to the presence of excessively charged toner, the thickness of the toner layer on the developing roller becomes excessive, causing problems such as wasteful supply and consumption of the toner amount exceeding the amount necessary for image formation.
In the developing process of electrophotography, the larger the absolute value of the average charge amount of toner (higher charge), the easier the toner particles adhere to the latent image portion of the photoreceptor, and the toner particle layer formed on the photoreceptor becomes thicker. There is a tendency to become. The thicker the toner particle layer on the photoconductor, the thicker the printed image formed by the toner transferred and fixed onto a recording medium such as paper. However, even if the printed image becomes excessive to some extent, printing is possible. The image density is almost unchanged. Eventually, the toner having a higher average charge amount as the thickness of the toner particle layer on the photoreceptor becomes excessive leads to wasteful consumption of the toner. In general, the charge amount distribution tends to be wider as the toner is highly charged. In general, the larger the absolute value of the average charge amount of toner, the more highly charged toner particles, but at the same time, the presence of toner particles having a relatively small absolute value of charge amount (low charge) cannot be ignored. In the electrophotographic development process, if a toner having an excessively high average charge amount is used, the toner particle layer formed on the latent image on the photoreceptor becomes excessively thick, and a relatively small portion of the toner particles are present. A phenomenon (toner scattering) in which low-charged toner particles are detached from the toner particle layer and contaminate the periphery of the photosensitive member is likely to occur.

  In general, the charge control agent added to the toner can achieve the effect of stabilizing the toner charge amount to some extent, but it is difficult to stabilize the absolute value of the toner charge amount to a low value, Even after continuous printing, it was not always perfect to obtain charging stability. Furthermore, if the charge control agent is added excessively in order to maintain a stable charge amount of the toner, the charge amount decreases and becomes unstable, the fluidity of the toner deteriorates, and the color of the toner deteriorates. In addition, there is a problem that the cost increases if the amount of the charge control agent added is large. As described above, it is difficult to control the stable charge amount while keeping the absolute value of the charge amount of the toner low by only adding the charge control agent.

As a technique for further stabilizing the charge amount in combination with the charge control agent, for example, a method of adding a conductive external additive such as a metal oxide to the toner surface has been proposed (see, for example, Patent Document 1). However, if a large amount of conductive external additive adheres to the toner surface, the toner tends to be insufficiently charged, and the image density tends to decrease as the number of printed sheets increases, which hinders the life of the toner. It was. In addition, when the conductive external additive is separated from the toner and transferred to the recording medium, the sharpness of the characters deteriorates, or when the temperature or humidity at which the toner is used and stored varies, the chargeability of the toner varies. There was another problem that the stability of the performance (environmental characteristics) was easily lost.

JP-A-2-7071

  The final object of the present invention is to provide an energy saving, low cost, and long life toner. For this reason, for each color toner, a sufficient image density can be obtained even at a low development potential and a low transfer potential at the time of printing, the amount of toner consumption is small, the toner does not fall off, and there is no background fogging in the printed image. Another object of the present invention is to provide a toner for developing an electrostatic charge with little change in charge amount over a long period of time.

The present invention has solved the above-mentioned problems by the configuration of technical features described in (1) to (4) below.
(1) An electrostatic charge image developing toner containing at least a binder resin and an antistatic composition, wherein the antistatic property is obtained by using a polyhydroxyalkanoate containing a crystal nucleating agent as the antistatic composition. A toner for developing electrostatic images, comprising 5 to 70% by mass of the composition.
(2) The electrostatic charge image development according to (1) above, wherein the crystal nucleating agent is contained in a range of 0.1 parts by mass or more and 10 parts by mass or less in 100 parts by mass of polyhydroxyalkanoate. Toner.
(3) The electrostatic image development according to (1) or (2), wherein the polyhydroxyalkanoate is poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) toner.
(4) The toner for developing an electrostatic charge image according to any one of (1) to (3), wherein the crystal nucleating agent is a sugar alcohol.

  According to the toner for developing an electrostatic charge image of the present invention, it is possible to reduce the amount of the charge control agent added in each color toner, and at the time of printing, the effect of suppressing the upper limit of the charge amount and the change in the charge amount over time. Development and transfer are possible even when the development potential and transfer potential are low, the toner consumption is small, the toner does not fall off, and a sufficient image density is obtained in the printed image. In addition, it is possible to provide a toner for developing an electrostatic charge having excellent characteristics such as no background fogging and little change in charge amount over a long period of time. As a result, according to the present invention, an energy-saving, low-cost, long-life color toner can be provided.

Embodiments of the present invention will be described below.
The toner of the present invention includes general electrostatic charges such as a binder resin, an antistatic composition and a positive charge control agent as well as a colorant, a negative charge control agent and a magnetic powder as constituents of toner particles. Various substances added to the image developing toner, infrared absorbers and the like can be appropriately contained, and various substances such as silica, carbon black, charge control agent and the like for controlling the fluidity and chargeability of the toner particles. Can be added as appropriate.

(Binder resin)
The binder resin used in the present invention can be selected from resins generally used as toners without any particular limitation. Examples of the binder resin include polyester, styrene resin, (meth) acrylic resin, styrene- (meth) acrylic copolymer resin, vinyl resin (for example, polyvinyl chloride, polyvinylidene chloride, etc.), polyamide Resin, polyether resin, urethane resin, epoxy resin, polyphenylene oxide resin, terpene phenol resin, polylactic acid resin, hydrogenated rosin, cyclized rubber, thermoplastic polyimide, and the like can be used. Among these, polyesters produced from carboxylic acids such as maleic acid, fumaric acid and phthalic acid, and alcohols such as bisphenol A (including EO / PO adducts) and ethylene glycol are dispersible with the same type of resin as PHA. Is preferable, and the durability of the toner is high.

(Antistatic composition)
The antistatic composition used in the present invention is polyhydroxyalkanoate (hereinafter referred to as PHA), which is a PHA to which a crystal nucleating agent is added in order to facilitate solidification from a molten state in the production stage. In the present invention, artificially synthesized PHA may be used, or PHA biosynthesized by a microorganism may be used. By using PHA biosynthesized by microorganisms, it is possible to obtain an effect that it is possible to produce a toner that can be replaced with a non-petroleum compound at the time of toner production, that is, carbon neutral and contains a resin component in consideration of the global environment. .

PHA which is a kind of polyester is a general term for a homopolymer obtained by polymerizing one kind of hydroxyalkanoic acid (also referred to as hydroxyalkanoate) and a copolymer obtained by copolymerizing two or more kinds of hydroxyalkanoic acid. More specifically, PHA is a polyester having a repeating structural unit represented by the formula (2), which is obtained by condensation polymerization of a hydroxyalkanoic acid represented by the formula (1).
PHA can be synthesized artificially, but it is also known as an organic polymer that microorganisms synthesize and accumulate as an energy storage substance from hydroxyalkanoic acid, which is a natural component in vegetable oil, and has biodegradability. Also, it has the feature of excellent compatibility with the environment.

HOCHR— (CH ₂ ) _n —COOH (1)

_{- [- CHR- (CH 2)} n -CO-O -] - ··· (2)

Here, R in the formulas (1) and (2) is an aliphatic saturated hydrocarbon group (alkyl group) or hydrogen, and is represented by the composition formula C _m H _{2m + 1} (where m and n are integers). And m ≧ 0, n ≧ 1). Examples of R include linear alkyl groups such as hydrogen, methyl group, ethyl group, propyl group, butyl group, pentyl group and hexyl group, and branched alkyl groups such as isopropyl group and tertiary butyl group.

  Specific examples of the hydroxyalkanoic acid in the case where the carbon atoms in the formula (1) are arranged in a straight chain include (m = 1, n = 1) 3-hydroxybutyrate (3HB), (m = 2 , N = 1) 3-hydroxyvalerate (3HV), (m = 0, n = 1) 3-hydroxypropionate, (m = 0, n = 2) 4-hydroxybutyrate, (m = 1, n = 2) 4-hydroxyvalerate, (m = 0, n = 3) 5-hydroxyvalerate, (m = 3, n = 1) 3-hydroxyhexanoate (3HH), 3-hydroxyheptanoate (m = 4, n = 1), 3-hydroxyoctanoate (m = 5, n = 1), 3-hydroxynonanoate (m = 6, n = 1), And 3-hydroxydecanoate (m = 7, n = 1).

Specific examples of PHA, which is a polymer of hydroxyalkanoic acid, include poly (3-hydroxybutyrate) (PHB), which is a 3HB homopolymer, and poly (3-hydroxy, which is a two-component copolymer of 3HB and 3HV. Butyrate-co-3-hydroxyvalerate) (PHBV), a binary copolymer of 3HB and 3HH, poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), 3HB and Examples thereof include poly (3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) (PHBHV), which is a three-component copolymer of 3HV and 3HH.

  Microorganisms that produce PHA produce and accumulate PHA as an energy source for survival. As a microorganism producing PHA, for example, Bacillus megaterium discovered in 1925 is the first microorganism producing PHB, which is a homopolymer of 3HB, and Capriavidus necator (former classification: Alkaligenes. Natural microorganisms such as Eutrophas (Alcaligenes eutrophus, Ralstonia eutropha), Alkaligenes latus (Alcaligenes latus), etc. are known, and PHB is produced and accumulated in the cells of these microorganisms.

Moreover, as a copolymer-producing bacterium of 3HB and other hydroxyalkanoic acid, PHBV and PHBH-producing bacterium Aeromonas caviae, poly (3-hydroxybutyrate-co-4-hydroxybutyrate) Alkaligenes eutrophus which is a producing bacterium is known. In particular, with respect to PHBH, in order to increase the productivity of PHBH, Alkaligenes eutrophus AC32 strain (Alcaligenes eutrophus AC32, FERM BP-6038) into which genes of the PHA synthase group have been introduced (T. Fukui, Y. Doi, J. Bateriol). , 179, p4821-2830 (1997)) and the like, and microbial cells in which PHBH is accumulated in the cells by culturing them under appropriate conditions can also be used. Furthermore, genetically modified microorganisms into which various PHA synthesis-related genes have been introduced can be used according to the PHA to be produced, and in order to increase the productivity, the culture conditions including the type of substrate may be optimized.
In particular, when paying attention to the point of having degradability as a biodegradable resin and a flexible material, PHA having many ester bonds is advantageous, and 3-hydroxyalkanoic acid having n = 1 in formula (1) is a monomer. PHA as a component is preferable because the interval between the ester bonds in the main chain is shortened. Among them, polymers having 3HB, 3HV, and 3HH as monomer components are preferable.

  As the antistatic composition, either a homopolymer PHA or a copolymer PHA can be used. Specific examples of PHA that can be used in the present invention include poly (3-hydroxybutyrate) (PHB), which is a 3HB homopolymer, and poly (3-hydroxybutyrate-), which is a two-component copolymer of 3HB and 3HV. Co-3-hydroxyvalerate) (PHBV), a polycomponent copolymer of 3HB and 3HH, poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), 3HB, 3HV and 3HH And poly (3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) (PHBHV), which is a three-component copolymer. Compared to a homopolymer, a copolymer tends to have a gentle viscosity change upon heating and is suitable as a resin used in the present invention. When PHA is a copolymer, the composition ratio of each monomer unit constituting the PHA is not particularly limited, but can be appropriately selected in consideration of the influence and effects on the thermal characteristics of the toner. Further, in consideration of the influence and effects on the thermal characteristics of the toner of the present invention, one kind of PHA may be used alone or a plurality of kinds of PHA may be blended and used in the present invention. good.

  When the PHBH alone is used as the PHA in the present invention, the composition ratio of 3HB to 3HH in the PHBH, that is, 3HB / 3HH is 99/1 to A range of 80/20 (mol / mol) is preferable as a resin that does not easily hinder the toner fixing strength and the non-offset temperature range.

  When the PHBHV alone is used as the PHA in the present invention, in the case of the PHBHV, for example, the content of 3HB unit is 1 to 95 mol%, the content of 3HV unit is 1 to 96 mol%, and the content of 3HH unit is 1 to 30 mol. % Is suitable as a resin that hardly interferes with the toner fixing strength and the non-offset temperature range.

  In general, when a polyester is produced industrially, since solidification from a molten state is slow at the time of molding processing, the productivity of the molding processing tends to be deteriorated, and PHA is particularly prominent. Therefore, by adding various crystal nucleating agents to PHA, the crystallization speed of PHA can be improved, it can be easily solidified from a molten state, and industrial production efficiency can be improved.

  Known crystal nucleating agents for polyester include, for example, inorganic simple substances such as Zn powder, Al powder, graphite, and carbon black for specific polyester; ZnO, MgO, A12O3, TiO2, MnO2, SiO2, Fe3O4, and the like. Metal oxides; nitrides such as aluminum nitride, silicon nitride, titanium nitride, boron nitride; inorganic salts such as Na2CO3, CaCO3, MgCo3, CaSO4, CaSiO3, BaSO4, Ca3 (PO4) 3; talc, kaolin, clay, clay, etc. Clays; calcium oxalate, sodium oxalate, calcium benzoate, calcium phthalate, calcium tartrate, magnesium stearate, polyacrylate, and other organic salts; polymer compounds such as polyester, polyethylene, and polypropylene There is that way.

Examples of the PHA crystal nucleating agent include talc, atomized mica, boron nitride, and calcium carbonate. More effective examples include organic phosphonic acid or organic phosphinic acid or esters thereof, or acids or esters thereof. Derivatives, and IV of the Periodic Table
There are methods of adding metal compounds such as group metal oxides, hydroxides and saturated or unsaturated carbonates.

  Furthermore, when sugar alcohols are used as more effective PHA crystal nucleating agents, the crystallization speed of PHA is remarkably improved, and PHA injection molding, film molding, blow molding, fiber spinning, extrusion foam molding, beads The workability in processing such as foam molding is improved, the processing speed is increased, and the crystallized region of the solidified PHA is miniaturized, which has the effect of improving the mechanical properties and transparency of the processed product. In addition, sugar alcohols are biodegradable because they are derived from natural products, so that the biodegradability of PHA as a biodegradable aliphatic polyester is not impaired.

  In the present invention, when a toner is produced using PHA produced by adding a crystal nucleating agent as an antistatic composition, the crystalline region in the solid state PHA is miniaturized. PHA is easily and finely and uniformly dispersed in the kneaded product, and PHA is easily and uniformly dispersed in each of the toner particles obtained through the pulverization process. As a result, it is expected to produce a homogeneous toner. it can. In addition, when used as an electrophotographic toner, the heat-fixed toner is expected to have an effect that contributes to prevention of high-temperature offset and high printing speed by solidifying quickly by miniaturizing the crystalline region. Is preferred.

  Since the crystal nucleating agent is likely to be finely dispersed as the particle size is smaller, the crystal nucleating agent is likely to be finely and uniformly dispersed in the production of the antistatic composition mainly composed of PHA. Since the generation point of crystal nuclei is increased, the solidification speed is increased, which is preferable because productivity is improved. In addition, in the toner according to the present invention, the antistatic composition becomes finer as the particle size of the crystal nucleating agent is smaller, so that the antistatic composition is easily finely dispersed in the toner particles. This is preferable because it can be used for the production of various toner particles, and also contributes to an increase in the solidification speed at the time of toner fixing, and further can be expected to contribute to the prevention of the high temperature offset and the increase in the printing speed. Various pulverizers can be used to reduce the particle size of the crystal nucleating agent.

  In addition, PHA containing a crystal nucleating agent tends to exhibit characteristics as an antistatic composition, and the charge amount of toner particles using the PHA is moderately suppressed, so that a stable and low charge amount distribution is easily obtained. I found something unique. In particular, although the mechanism for stabilizing the charge distribution of the toner containing PHA containing a crystal nucleating agent to be stabilized is not clear, the electrical resistivity of the crystal nucleating agent is lower than that of the binder resin constituting the toner. Presumed to be related.

  When the toner contains a PHA containing a crystal nucleating agent, a sufficient image density can be obtained even at a low development potential and a low transfer potential during printing in the electrostatic charge image developing method, the toner consumption is small, and the toner falls off. An electrostatic charge developing toner that does not occur and does not cause background fogging in a printed image can be obtained. In particular, when sugar alcohols are selected as the crystal nucleating agent, the crystal region in the solid state PHA progresses particularly well, so that PHA is uniformly dispersed in the toner particles, thereby obtaining uniform toner particles. The effect contributing to the increase in printing speed becomes remarkable. Moreover, although PHA is also known as a biodegradable resin, sugar alcohols are derived from natural products and have biodegradability, so even if they are used together, the biodegradability of PHA is not impaired.

In the toner according to the present invention, sugar alcohols that can be preferably used as an antistatic composition and can also be preferably used as a crystal nucleating agent for PHA include meso-erythritol having 4 carbon atoms, D-arabitol having 5 carbon atoms, Sugar alcohol derived from monosaccharides such as ribitol, xylitol, galactitol having 6 carbon atoms, D-mannitol, L-mannitol, D-sorbitol, myo-inositol, scyllo-inositol, and sugars derived from disaccharides such as maltitol and lactitol Examples include alcohol. In particular, the melting point is in the range of 70-190 ° C.
meso-erythritol (melting point 119 ° C), D-arabitol (melting point 101-104 ° C), ribitol (melting point 102-105 ° C), xylitol (melting point 94-97 ° C), galactitol (melting point 188-190 ° C), D- Mannitol (melting point: 167-170 ° C.), L-mannitol (melting point: 165 ° C.), D-sorbitol (melting point: 98-100 ° C.), maltitol (melting point: 149-152 ° C.), lactitol (melting point: 70-149 ° C.) Among them, sugar alcohols derived from monosaccharides having 4 to 6 carbon atoms, that is, meso-erythritol, D-arabitol, ribitol, xylitol, galactitol, D are preferable. -Mannitol, L-mannitol, and D-sorbitol are more preferable because the effect of improving the crystallization rate of PHA is particularly remarkable.

Regarding the constitution of the antistatic composition contained in the toner according to the present invention, the amount of sugar alcohol added as a crystal nucleating agent to PHA is in the range of 0.1 to 10 parts by mass with respect to 100 parts by mass of PHA. If so, a sufficient crystallization promoting effect can be obtained, and dispersion in PHA is good, which is preferable. When the addition amount of the sugar alcohol is less than 0.1 parts by mass, the number of crystal nuclei is insufficient, and a sufficient crystallization promoting effect cannot be obtained. When the addition amount exceeds 10 parts by mass, the addition effect only reaches saturation. In addition, it becomes difficult to knead and disperse uniformly. A more preferable addition amount range of the sugar alcohol as the crystal nucleating agent is 0.3 part by mass or more and 7 parts by mass or less. Further, the antistatic composition may contain an antioxidant, an ultraviolet absorber, a colorant, a plasticizer, a lubricant, an inorganic filler, an antistatic agent and the like as other components. The amount of these other components added is not particularly limited as long as it does not impair the effects of the PHA and the crystal nucleating agent and various properties of the toner according to the present invention.
The antistatic composition can be easily prepared by a known method generally used as a method for preparing a known resin composition. For example, a crystal nucleating agent composed of PHA such as P3AH and sugar alcohols and, if necessary, other components are mixed, and then kneaded with an extruder, a roll mill, a bumper mixer, etc. to form pellets and used for molding A method, a method of preparing a master batch of a high concentration of a crystal nucleating agent composed of sugar alcohols in advance, mixing this with a biodegradable aliphatic polyester at a desired ratio, and the like can be used. In addition, for example, a method of dispersing a fine powder of a crystal nucleating agent composed of a sugar alcohol in a solvent such as chloroform and then adding PHA and stirring it (casting off the solvent) to form a mixture can be used.

  In the toner of the present invention, the proportion of PHA contained in the antistatic composition is 5 to 70% by mass in 100% by mass of toner particles excluding external additives. More preferably, it is 10-50 mass%, More preferably, it is 15-40 mass%. A positively charged toner with a stable charge amount can be obtained by blending an antistatic composition so as to be in such a PHA range and using it together with a binder resin. If the PHA ratio is less than 5% by mass, the toner charge amount tends to increase during continuous printing, and it is necessary to set the development potential and transfer potential high in the development step and transfer step, respectively. Further, since the printed toner layer tends to be thick, the toner consumption tends to be excessive with respect to the print density. Even if the proportion of PHA is increased beyond 70% by mass, there is a possibility that the further antistatic effect, that is, the effect of suppressing the upper limit of the charge amount or the effect of suppressing the change of the charge amount over time may not be remarkably improved. is there. When the molecular weight distribution of PHA is narrow, if the PHA ratio in the toner particles is excessive, the fixable temperature range may be narrowed.

  The acid value of the polyester applied to the present invention is preferably 30 mgKOH / g or less, more preferably 20 mgKOH / g or less, and still more preferably 10 mgKOH / g or less. When the acid value is larger than 30 mgKOH / g, the blocking resistance (preservability) may be deteriorated, which is not preferable.

(Charge control agent)
In the present invention, it is necessary to add a negatively charged or positively chargeable charge control agent.
Examples of negative charge control agents that can be added include metal-containing azo dyes such as Cr, Co, Al, and Fe, salicylic acid metal compounds, alkyl salicylic acid metal compounds, curlyx arene compounds, boron complexes, and polymer type charge control agents. And so on.
Examples of positively chargeable charge control agents that can be added include nigrosine dyes, azine compounds, quaternary ammonium salt compounds, triphenylmethane compounds, imidazole compounds, polyamine resins, and styrene-acrylic copolymer resins. be able to.
These charge control agents can be used alone or in combination of two or more according to the toner chargeability design, and negatively charged and positively charged ones can be used in combination.
The total content of the charge control agent in the toner is preferably about 0.10 to 10% by mass with respect to 100% by mass of the toner. If the content of the charge control agent is less than the above range, there is a risk that the toner charge amount distribution becomes too wide and the amount of waste toner increases, and if the content exceeds the above range, it becomes difficult to charge or the color becomes poor. Image quality may be reduced.

  In addition, a mold release agent, a coloring agent, a negative charge control agent, magnetic powder, an additive, etc. can be added as optional components. In the case of a flash fixing toner by infrared irradiation, an infrared absorber can also be added. Hereinafter, arbitrary components will be described.

(Release agent)
When adding a release agent as a component of the toner, select a substance having a melting point lower than that of the binder resin constituting the toner, and select an appropriate release agent according to the composition and thermal characteristics of the binder resin. It ’s fine. Specifically, a substance having a softening point (melting point) of 50 to 170 ° C., more preferably 70 to 150 ° C., can be preferably used as a release agent. When the softening point of the release agent is lower than 50 ° C., the toner has insufficient blocking resistance and storage stability, and when it exceeds 170 ° C., the fixing temperature may be too high. When the temperature is 70 ° C. or higher, the fusion of the toner to the charging blade is remarkably improved, and when the temperature is 150 ° C. or lower, the fixing temperature is lowered.

Examples of the release agent that can be used in the present invention include polyolefin waxes such as polyethylene wax, polypropylene wax, polybutene wax, and modified polyethylene wax, synthetic waxes such as Fischer-Tropsch wax, and paraffins such as natural paraffin, microwax, and synthetic paraffin. Petroleum wax such as wax and microcrystalline wax, carnauba wax, candelilla wax, rice wax, hydrogenated castor oil, acidic olefin wax, maleic acid ethyl ester, maleic acid butyl ester, stearic acid methyl ester, stearic acid butyl ester, palmitic Ester waxes composed of fatty acid esters such as acid cetyl esters and montanic acid ethylene glycol esters or partially saponified products thereof; Phosphoric acid amide, oleic acid amide, palmitic acid amide, lauric acid amide, behenic acid amide, methylene bis stearamide, amide waxes such as ethylene bis stearamide and the like.
Moreover, these mold release agents can be used individually or in combination of 2 or more types. If necessary, release agents having different softening points (melting points) can be used together and mixed.

  The content of the release agent in the toner of the present invention may be appropriately designed according to the thermal characteristics of the binder resin and ease of dispersion of the release agent when used as a toner for a heat fixing system. When the toner is produced by the melt-kneading pulverization method, the range of 0.1 to 15% by mass is preferable, preferably 0.5 to 10% by mass, more preferably, based on the total toner mass. Is 1-8 mass%. If the content of the release agent is less than the above range, the viscosity when the toner is melted is unlikely to decrease, so that the fixing strength of the image may be weakened, or the toner is likely to be fused to the heat fixing roller. Offset or paper (recording medium) wrapping may occur. On the other hand, if the above range is exceeded, the fluidity of the toner may be deteriorated and charging may be difficult, and the release agent may be detached from the toner particles and adhere to members inside the electrophotographic apparatus such as a photoconductor and a developing roller. Therefore, there is a risk that the image formation by electrophotography may be hindered. On the other hand, the content of the release agent in the toner of the present invention when used as a toner for a fresh fixing system may be appropriately designed in consideration of the efficiency of melting by light, and the toner is produced by a melt kneading and pulverizing method. In this case, the range of 0.1 to 50% by mass is preferable based on the total toner mass.

(Coloring agent)
A known colorant can be added to the toner of the present invention.
As the yellow colorant, for example, a condensed azo compound, an isoindolinone compound, an anthraquinone compound, an azo metal complex methine compound, a compound represented by an allylamide compound, or the like is used. Specifically, C.I. I. Pigment Yellow-1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 15, 16, 17, 23, 24, 60, 62, 65, 73, 74, 75, 83 93, 94, 95, 97, 99, 100, 101, 104, 108, 109, 110, 111, 117, 122, 123, 128, 129, 138, 139, 147, 148, 150, 155, 166, 168 169, 177, 179, 180, 181, 183, 185, 191: 1, 191, 192, 193, 199, etc., pigment systems such as C.I. l. solventYellow33, 56, 79, 82, 93, 112, 162, 163, C.I. I. A dye system such as disperse Yellow 42.64.2011.211 can be used. These yellow colorants can be used alone or in combination of two or more.

  Examples of the magenta colorant include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds. Specifically, C.I. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 39, 40, 41, 48, 48: 2, 48: 3, 48: 4, 49, 50, 51, 52, 53, 54, 55, 57, 57: 1, 58, 60, 63, 64, 68, 81, 81: 1, 83, 87, 88, 89, 90, 112, 114, 122, 123, 146, 163, 166, 169, 177, 184, 185, 202, 206, 207, 209, 220, 221, 238, 254, 269, C.I. I. Pigment violet 19; C.I. I. Butlet 1, 2, 10, 13, 15, 23, 29, 35, etc. can be used. These magenta colorants can be used alone or in combination of two or more.

As the cyan colorant, for example, a copper phthalocyanine compound and a derivative thereof, an anthraquinone compound, a basic dye lake compound, and the like can be used.
Specifically, C.I. I. Pigment Blue 1, 2, 3, 7, 15, 15: 1, 15: 2, 15: 3, 15: 4, 16, 17, 60, 62, 66; I. Bat Bull-6; I. Acid Bull-45 etc. can be used. These cyan colorants can be used alone or in combination of two or more.

  As a colorant for the color toner, a so-called master batch dispersed in a high concentration in a resin that can be a binder resin in advance may be used.

As the black colorant, for example, carbon black such as acetylene black, lan black and aniline black, magnetic particles such as graphite, nigrosine, iron black, iron trioxide, manganese iron oxide, zinc iron oxide, nickel iron oxide, etc. are used. In addition to the above, it is possible to use a material that is toned in black using the yellow / magenta / cyan colorant.
The carbon black can be used without being limited by the number average particle size, oil absorption, PH, etc., and the following are commercially available products. For example, trade names: REGAL 400, 660, 330, 300, SRF-S, STERING SO, V, NS, and R manufactured by Cabot Corporation of the United States can be given. Moreover, the brand name made from Columbian Carbon Japan: RAVEN H20, MT-P, 410, 420, 430, 450, 500, 760, 780, 1000, 1035, 1060, 1080. In addition, trade names manufactured by Mitsubishi Chemical Corporation: # 5B, # 10B, # 40, # 2400B, MA-100, and the like can be given. These carbon blacks can be used alone or in combination of two or more.

The content of the colorant in the color toner may be determined as an optimum amount for each color, but is preferably in the range of 1 to 20% by mass, particularly preferably 4 to 9% by mass in 100% by mass of the toner. is there. In consideration of light transmittance of an OHP film or the like, 11% by mass or less is preferable. If the content of the colorant is less than 1% by mass, it is difficult to increase the image density and the toner consumption may increase. If it exceeds 20% by mass, the charge tends to be unstable and the image quality tends to deteriorate.
The black colorant content in the black toner is preferably in the range of 0.1 to 20% by mass, more preferably 1 to 10% by mass, still more preferably 1 to 5% by mass, particularly 100% by mass of the black toner. Preferably it is 1-3 mass%. If the carbon black content is less than the above range, the image density may decrease and the toner consumption may increase. If it exceeds the above range, the image quality tends to be lowered, and the toner moldability is also lowered.

(External additive)
The toner of the present invention is effective in obtaining a stable triboelectric state by increasing fluidity and preventing aggregation (blocking) between the toner particles. Therefore, the toner base particles are mixed with an external additive. It is preferable that the external additive is attached to the surface.
As the external additive, various inorganic or organic external additives can be used. In particular, silica, titanium oxide, alumina, zinc oxide, magnesium oxide, strontium titanate, Inorganic fine powders such as metal soaps (lithium stearate, zinc stearate, etc.) can be preferably used.
The amount of external additive mixed and adhered varies depending on the external additive used and the average particle size and particle size distribution of the toner particles, and may be appropriately designed. 05-10 mass parts, Furthermore, 0.1-8 mass parts is suitable.
If the mixing amount is less than 0.05 parts by mass, it may be difficult to obtain the effect of improving fluidity and the effect of preventing aggregation due to storage in summer and the like, and if the mixing amount is more than 10 parts by mass, it does not adhere to the toner base particles. The free external additive may be generated in the process, and the free external additive may adhere to the photoconductor to cause filming, or it may accumulate inside the developing tank and cause troubles such as deterioration of the charging function of the developer. It is not preferable to cause it.
Further, the external additive is more preferably hydrophobic fine particles because it is not easily affected by the humidity environment, and for example, hydrophobic silica is more preferable. Examples of the hydrophobic silica include hydrophilic silica obtained by reacting or adhering methylchlorosilane, silane coupling agent, high molecular weight organopolysiloxane, hexamethyldisilazane (HMDS), organopolysiloxane, polyethylene wax, etc. Hydrophobic silica, etc., which has been hydrophobized by sequentially reacting an aminoalkylsilane compound and a diisocyanate compound, etc. can be exemplified. Among them, a treated product of aminoalkylsilane in which the hydrophobizing component is chemically bonded to the silica surface by a chemical reaction, etc. This is preferable in terms of imparting durability to the toner image. For example, dimethyldichlorosilane, monooctyltrichlorosilane, hexamethyldisilazane, silicone oil or the like may be used as a treatment agent for imparting negative chargeability. Aminosilane or the like may be used as a treatment agent that imparts chargeability.

  In addition, magnetite, ferrite, conductive titanium, antimony oxide, tin oxide, cerium oxide, hydrotalcite compounds, acrylics other than those for improving fluidity for the purpose of adjusting the electrical resistance of toners and abrasives as external additives An appropriate amount of fine powders such as beads, silicone beads, and polyethylene beads may be mixed, and the mixing amount is preferably 0.005 to 10 parts by mass with respect to 100 parts by mass of the toner.

  Furthermore, resin fine powders such as polytetrafluoroethylene resin powder and polyvinylidene fluoride resin powder may be attached as an external additive. The proportion of the resin fine powder added to the toner can be appropriately selected from the range of 0.01 to 8 parts by mass, preferably 0.1 to 5 parts by mass, and more preferably 0 to 100 parts by mass of the toner. .1 to 4 parts by mass.

  The toner for developing an electrostatic charge image of the present invention can be produced by a melt-kneading pulverization method. The manufacturing method will be described below.

(Kneading process)
In the kneading step, a mixture of raw materials is hot-melt kneaded to obtain a kneaded product in which the antistatic composition and, if necessary, the other optional components are dispersed in a binder resin.
When the toner of the present invention is prepared by the melt-kneading pulverization method, first, a binder resin, an electrostatic composition and, if necessary, the above optional components are mixed with a double cone mixer, a V-type mixer, a drum-type mixer, a super mixer. A raw material mixture in a coarsely pulverized state is prepared using a mixing device such as a Henschel mixer or a Nauter mixer. A batch type (for example, a pressure kneader, a Banbury mixer, etc.) or a continuous hot melt kneader However, a monoaxial or biaxial continuous extruder is preferable because of the advantage of continuous production. For example, KTK type twin screw extruder manufactured by Kobe Steel, TEM type twin screw extruder manufactured by Toshiba Machine Co., Ltd., twin screw extruder manufactured by Kay CK, PCM type twin screw extruder manufactured by Ikekai Tekko Co., Ltd., Kuriyama Manufacturing Co., Ltd. A twin-screw extruder manufactured by Co., Ltd., a co-kneader manufactured by Busus Co., or an open roll type continuous kneader can be used. In particular, when an open roll type continuous kneader is used, the dispersion of the raw materials in the kneading can be advanced to a high degree, and not only can the uniform pulverized toner particles be obtained, but also the shape of the kneaded product after the kneading process is completed Therefore, it can be used as it is in the next pulverization and classification process, so that it is convenient for handling and is easy to clean.

In the open roll type continuous kneader, two rolls, a front roll and a back roll, are arranged in parallel, and the raw material passes through the gap between the two rolls, and kneading is performed by mechanical shearing force at that time. is there. In addition, this roll has a spiral groove and a transverse groove, and these grooves are provided in the vicinity of the other end of the roll from the action of causing the raw material to bite into the roll gap and the raw material supply section provided in the vicinity of one end of the roll. There exists an effect | action which accelerates | stimulates conveying a kneaded material to the provided kneaded material discharge | emission part. The raw material can be appropriately supplied not only from the roll end but also from the first half, middle and second half of the roll according to the characteristics of the raw material.
The open roll type continuous kneader can exhibit heating and cooling functions by passing a heating medium such as oil or hot water through the front roll and a cooling medium such as water through the back roll. Thereby, kneading can be performed at an appropriate temperature, and by performing cooling together with kneading, it is not necessary to employ a cooling process as a separate process, and the process can proceed directly to the pulverization process. As the open roll type continuous kneader, “Neekex (trade name)” manufactured by Nippon Coke Industries, Ltd. can be suitably used.

(Cooling process)
Thereafter, the kneaded product is cooled and solidified by a cooling step.

(Crushing classification process)
In the pulverization and classification step, the cooled and solidified kneaded product is pulverized and classified to obtain a classified toner.
First, coarse pulverization is performed with a crusher, hammer mill, feather mill, etc., and fine pulverization is performed with a jet mill, counter jet mill, high-speed rotor rotary mill, etc., and pulverized to a predetermined toner particle size step by step.
Then, the toner is classified by an inertia class elbow jet, a centrifugal class microplex, a DS separator, a dry air classifier or the like to obtain a classified toner having a volume average particle diameter of 3 to 18 μm.
The coarse powder obtained at the time of classification may be returned to the pulverization and classification process, and the fine powder may be returned to the kneading process and reused. When the fine powder is reused, the production conditions including the addition amount of the fine powder are appropriately controlled so that the composition after toner formation and the molecular weight distribution of the resin are appropriate.

Next, an external addition process for attaching an external additive to the classified toner is performed as necessary.
A predetermined amount of the classified toner and various external additives are blended, and the mixture is stirred and mixed by dry blending, whereby the external additive can be attached (externally added) to the toner particles. Examples of the agitation / mixing device (external addition machine) include a high-speed agitator that gives shearing force to the powder, such as a double cone mixer, a V-type mixer, a drum-type mixer, a super mixer, a Henschel mixer, and a Nauter mixer. .
In the external addition process, in order to prevent toner particles and various external additive particles inside the external additive machine from aggregating due to frictional heat due to collision or friction between the particles or the internal structure of the external additive machine, Care should be taken so that the temperature of each material inside the external machine does not become too high. As a method for preventing the temperature inside the external machine from increasing, for example, an external machine having a water cooling function for cooling the inner wall of the external machine from the outside by running water or the like may be used.

  The toner of the present invention is obtained by the above-described method, and the volume average particle diameter is preferably 3 μm to 15 μm, more preferably 5 μm to 10 μm. If the volume average particle size is less than 3 μm, the amount of ultrafine powder less than 2 μm increases, so fogging, image density reduction, occurrence of black spots and filming on the photoconductor, occurrence of fusing on the developing sleeve and layer thickness regulating blade, Cause etc. On the other hand, if it exceeds 15 μm, the resolution is lowered and a high-quality image cannot be obtained.

  In the present invention, the volume average particle diameter was determined by measuring the volume distribution with a 100 μm aperture tube using a Coulter counter TA-II type (manufactured by Coulter).

The circularity of the toner of the present invention is 0.80 to 0.98, preferably 0.90 to 0.96. If the circularity is less than 0.80, the fluidity is inferior and the charge amount is insufficient and the image density is likely to be lowered. If it exceeds 0.98, the charge amount is excessive and the toner consumption is easily increased. Since the toner tends to roll, it is difficult to scrape toner particles with the cleaning blade, and the cleaning failure of the photosensitive member and the accompanying image failure are likely to occur.
The circularity is
Circularity = π · (diameter of circle equal to particle image area) / (perimeter of particle image)
The flow type particle image analyzer (manufactured by Sysmex, trade name: FPIA-2000).

The obtained toner can be used for non-magnetic one-component development method and non-magnetic two-component development method when it does not contain magnetic material, and it can be used for magnetic one-component development method and magnetic two-component development method when it contains magnetic powder. it can. Regardless of whether it is non-magnetic or magnetic, the two-component development method is used as a developer in which toner and carrier are mixed.
As the carrier in the two-component development system, for example, nickel, cobalt, iron oxide, ferrite, iron, glass beads and the like can be used. These carriers may be used alone or in combination of two or more. The average particle size of the carrier is preferably 20 to 150 μm. In addition, the surface of the carrier may be coated with a coating agent such as a fluorine resin, an acrylic resin, or a silicone resin.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited by these Examples.

<Preparation of antistatic composition>
100 parts by mass of PHBH (weight average molecular weight: 400000, number average molecular weight: 5000) pellets, and 2.0 parts by mass of fine powder of galactitol (purity 98%, reagent manufactured by Tokyo Chemical Industry Co., Ltd.) pulverized using a mixer mill, Were mixed and hot melt kneaded to prepare an antistatic composition.

<Production of toner>
The following raw materials were uniformly mixed with a Henschel mixer, and then melt-kneaded and granulated with an open roll continuous kneading granulator (product name: Nidex MOS type, manufactured by Nippon Coke Industries, Ltd.).
-Binder resin Polyester: 27.0 parts by mass (content ratio in toner particles 24.9% by mass)
(Product name: FC-916, manufactured by Mitsubishi Rayon Co., Ltd.)
Antistatic composition 73.0 parts by mass (content ratio in toner particles 67.3% by mass)
Colorant: Magenta pigment: 4.5 parts by mass (content ratio in toner particles: 4.1% by mass)
(Product name: Pigment Red, manufactured by Dainichi Chemical Industry Co., Ltd.)
・ Positive charge control agent Azo-containing metal compound: 1.0 part by mass (0.9% by mass in toner particles)
(Product name: BONTRON S-34, manufactured by Orient Chemical Industries)
Wax polyethylene wax: 3.0 parts by mass (content ratio in toner particles 2.8% by mass)
(Product name manufactured by Hoechst: PE-130)
Next, the kneaded granulated product was cooled, pulverized with a jet mill, and classified with an airflow classifier to obtain toner particles having a volume average particle size of 9 μm. The toner of Example 1 was obtained by uniformly mixing 100 parts by mass of the toner particles and 0.6 part by mass of hydrophobic silica (trade name: TS-530, manufactured by Cabot Corporation) using a Henschel mixer.

  The binder resin of Example 1 is 92.0 parts by mass (content ratio in toner particles 84.8% by mass), and the antistatic composition is 8.0 parts by mass (content ratio in toner particles 7.4% by mass). The toner of Example 2 was obtained with the same number of parts by mass except for the change.

  The binder resin of Example 1 is 70.0 parts by mass (content ratio in toner particles 64.5% by mass), and the antistatic composition is 30.0 parts by mass (content ratio in toner particles 27.6% by mass). The toner of Example 3 was obtained with the same number of parts by mass except for the change.

The toner of Example 4 was obtained in the same manner as in Example 3 except that the colorant of Example 3 was changed to the following black pigment. The content ratio of the antistatic composition in the toner of Example 4 in the toner particles is 27.0% by mass.
Colorant carbon black: 7.0 parts by mass (content ratio in toner particles: 6.3% by mass)
(Product name: REGAL330R manufactured by Cabot)

  Except for changing the binder resin of Example 3 to 70.0 parts by mass of the following styrene acrylate ester copolymer (trade name: Hymer ST-305, manufactured by Sanyo Kasei Co., Ltd.), the same formulation was used. Obtained.

  0.18 parts by mass of the positively chargeable charge control agent of Example 3 (0.17% by mass of the positively chargeable charge control agent in the toner particles, 27.9% by mass of the antistatic composition in the toner particles) The toner of Example 6 was obtained with the same number of parts by mass except that the percentage was changed to%).

  10.0 parts by weight of the positively chargeable charge control agent of Example 3 (8.5% by weight of the positively chargeable charge control agent in the toner particles, 25.5% by weight of the antistatic composition in the toner particles) The toner of Example 7 was obtained with the same number of parts by mass, except that the toner was changed to%).

[Comparative Example 1]
The binder resin of Example 1 was 20.0 parts by mass (content ratio in toner particles 18.4% by mass), and the antistatic composition was 80.0 parts by mass (content ratio in toner particles 73.7% by mass). A toner of Comparative Example 1 was obtained with the same mass parts except for the above.

[Comparative Example 2]
The binder resin of Example 1 was 95.0 parts by mass (content ratio in toner particles: 87.6% by mass), and the antistatic composition was 5.0 parts by mass (content ratio in toner particles: 4.6% by mass). The toner of Comparative Example 2 was obtained with the same mass parts except for the above.

  Table 1 shows the raw material ratio (parts by mass) blended in the production of the toners of Examples and Comparative Examples, and Table 2 shows 100% by mass of the toner particles (excluding external additives) of Examples and Comparative Examples. The converted raw material ratio (% by mass) is shown.

<Evaluation of toner>
The toners of Examples 1 to 5 and Comparative Examples 1 and 2 are loaded into a non-magnetic one-component developing type printer,
Using an A4 size paper with a basis weight of 65 g / m ² as a recording medium and using a test image (including a solid image of 25 mm × 25 mm) with a printing rate of 5%, in an environment of room temperature 25 ° C. and humidity 50%, Test sheet for fixing test by printing 50 unfixed images for fixing temperature test under conditions of low development potential and low transfer potential (development voltage: + 250V, primary transfer voltage: 800V) at a printing speed of 30 sheets per minute Got. Subsequently, the fixing machine was operated to perform monochromatic printing on 5000 sheets. The weight of the toner cartridge was measured before and after printing, and the toner consumption was evaluated from the increased amount. The image density and the background fog were evaluated by performing the following measurements for each test paper and selecting 10 printed papers in the vicinity of the 5000th sheet as random test papers. For the numerical data, an average value was calculated for each test sheet, and evaluation was performed based on each average value of 10 test sheets.
(Image density)
Using a spectral densitometer (trade name: 939 spectral densitometer manufactured by X-RITE Co., Ltd.), 10 points each of the density of a solid image of 25 mm × 25 mm were measured for 10 sheets of the test paper, and a total of 100 measurement values were obtained. The average value was used for image density evaluation. The image density was evaluated as follows.
○ The average image density value is 1.0 or more (sufficient image density)
× Image density value is less than 1.0 on average (image density was insufficient)
(Ground fog)
Using a whiteness meter (manufactured by Nippon Denshoku Industries Co., Ltd., trade name: ZE-2000), the paper before printing was used as a standard for whiteness, and the whiteness (ΔWB value) was measured for the white portion of the 10 test sheets. ) Was measured at 10 points, and the average of a total of 100 measurement values was used for the evaluation of ground fog.
○ Whiteness (ΔWB value) was less than 2.0 and no background fogging was observed. × Whiteness (ΔWB value) was 2.0 or more and background fogging was observed (toner consumption).
The weight of the toner cartridge was measured before and after monochrome printing of 5000 sheets, and the amount of toner consumed when printing 5000 sheets was evaluated from the increased amount.
○ The toner consumption at the time of printing 5000 sheets is 150 g or less, which is good. × The toner consumption at the time of printing 5000 sheets is over 150 g, which is excessive (toner dropping).
Toner dropping is a phenomenon that occurs because the charge amount of toner particles is too low. The inside of the printer after printing 5000 sheets was visually observed, and the presence or absence of toner dropping from the periphery of the developing machine was visually confirmed.
○ No toner drop was observed × Toner drop was observed (toner scattering)
Toner scattering is a phenomenon that occurs because the average charge amount of toner is too high. The inside of the printer after printing 5000 sheets was visually observed, and the presence or absence of toner scattering from the periphery of the photoreceptor was visually confirmed.
○ No toner scattering was observed × Toner scattering was observed (fixing temperature test)
Using an external fixing machine with a silicone rubber roller, setting the roller temperature in steps of 80 ° C to 5 ° C at a fixing speed of 130 mm per second, fixing the test paper for the fixing test, and visually evaluating whether or not offset occurs The temperature range where no offset occurs was defined as the fixing temperature range.
(Electric resistance value)
The toners of Examples and Comparative Examples were formed into pellets at a pressure of 200 kgf / cm ^{2 so} that the diameter was 2.5 cm and the thickness was 5.0 mm, and the electric resistance value was measured.

  Table 3 shows the evaluation results of the toners of Examples and Comparative Examples.

In Examples 1 to 3, 5 to 7 (color toner) and Example 4 (black toner), all the toners have high image density, no background fogging occurs, toner consumption is suppressed, and toner drops are reduced. There was no toner scattering, and the fixing temperature range was wide and favorable from low to high. Each of the toners in the examples has an electric resistance value in the lower range of 1.0 × 10 ^{10 to} 5.0 × 10 ¹⁰ Ω · cm, and the charge becomes high even when the toner is continuously used. It is presumed that stable printing can be continued because it is saturated with an appropriate charge amount without being continued.
Thus, if the toner particles contain an antistatic composition having an appropriate concentration range, the amount of the charge control agent is as small as 0.17% by mass as in the toner of Example 6, or Even if the amount of the charge control agent is as large as 8.5% by mass like the toner of No. 7, a toner capable of obtaining a stable image by suppressing fluctuation of the charge amount distribution in continuous printing is obtained. Can do it.
On the other hand, in Comparative Example 1 in which the antistatic composition exceeds 70% by mass of the total toner particles, toner scattering was not observed, but the image density was low, background fogging was observed, and toner consumption was low. Excessive toner was observed. It seems that the absolute value of the charge was lowered because the amount of the antistatic composition was too large. It is known that when toner with too low electric resistance value is used continuously, the charge amount does not reach the appropriate range and the image density is insufficient, the background fog is increased, and the toner drops tend to occur. This suggests that the electric resistance value of the toner No. 1 was 0.87 × 10 ¹⁰ Ω · cm which was too small. As for the high image density, generally, when the charge amount of the toner is low, the image tends to be thin. In Comparative Example 1, the image was unclear, but at the same time, due to the occurrence of background fogging, The apparent image density is high.
In Comparative Example 1, high temperature offset was remarkable in the fixing test. This is presumably because the molecular weight distribution of the antistatic composition may be lower than that of the binder resin, and the high molecular weight component effective for preventing high temperature offset was insufficient.
On the other hand, in Comparative Example 2 in which the antistatic composition was less than 5% by mass of the total toner particles, the image density was good and no background fogging or toner dropping was observed, but the toner consumption was large. There are two possible causes for the high toner consumption. The first cause is considered that the toner of Comparative Example 2 is too charged because the amount of the antistatic composition is too small, and the toner adheres excessively to the latent image on the photoreceptor. The second cause of the large amount of toner consumption is that the toner of Comparative Example 2 is highly charged, so that the toner charge amount distribution is wide, and relatively lowly charged toner particles are present so that they cannot be ignored. It is conceivable that the apparent toner consumption has increased because low-charged toner particles are detached from the toner particle layer on the photoconductor to cause toner scattering that contaminates the periphery of the photoconductor. When a toner having a large electric resistance value is continuously used, the toner consumption tends to increase as a result of the charge amount of the toner increasing beyond an appropriate range. From the result of excessive toner consumption in the toner of Comparative Example 2, it is considered that the electrical resistance value of this toner is 10.7 × 10 ¹⁰ Ω · cm larger than the appropriate range.
The antistatic composition used in the toner of the present invention is stable while maintaining a low absolute value of the toner charge amount, although the basic structure is equivalent to a general synthetic polyester resin (PHA). The antistatic composition has a remarkable effect of controlling the charged amount. The reason for this is not clear, but the crystal nucleating agent added to promote the solidification of the synthetic polyester from the molten state stably controls the charge amount while keeping the absolute value of the charge amount of the toner low. The possibility of acting as an active ingredient of the antistatic composition of the present invention is considered.
As described above, according to the toner for developing an electrostatic charge image of the present invention, in each color toner, a resin component that can be replaced with a non-petroleum compound, that is, carbon neutral, can be added at the time of toner production, and charge control can be performed. The addition amount of the agent can be reduced, and at the time of printing, it has the effect of suppressing the upper limit of the charge amount and the effect of suppressing the change in the charge amount over time. Transfer is possible, toner consumption is low, toner drop does not occur, sufficient image density is obtained in printed images, background fogging does not occur, and there is little change in charge amount over a long period of time In addition, a toner for developing electrostatic charge can be provided. As a result, according to the present invention, an energy-saving and low-cost color toner in consideration of the global environment can be provided.

Claims (4)

  An electrostatic charge image developing toner containing at least a binder resin and an antistatic composition, wherein a polyhydroxyalkanoate containing a crystal nucleating agent is used as the antistatic composition, and the antistatic composition is treated as 5 A toner for developing an electrostatic image, characterized by containing -70% by mass.   2. The electrostatic image developing toner according to claim 1, wherein the crystal nucleating agent is contained in a range of 0.1 parts by mass or more and 10 parts by mass or less in 100 parts by mass of polyhydroxyalkanoate.   The electrostatic image developing toner according to claim 1, wherein the polyhydroxyalkanoate is poly (3-hydroxybutyrate-co-3-hydroxyhexanoate).   The electrostatic image developing toner according to claim 1, wherein the crystal nucleating agent is a sugar alcohol.