JP2003167372A - Electrostatic charge image developing toner and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner having good fluidity, heat resistance, durability and preservation stability and less liable to cause shortening of the service life of a developer due to spending of a carrier spent (carrier contamination) by the toner and shortening of the service life of a photoreceptor due to filming of the photoreceptor with the toner. <P>SOLUTION: In the toner consisting essentially of a fixing resin and a wax, the fixing resin contains a vinyl copolymer obtained by polymerization in the presence of a polyethylene wax having <10 mPa.s melt viscosity at 140°C as at least a constituent component, the wax is a polyethylene wax containing wax having ≥10 mP.s melt viscosity at 140°C and a penetration of ≤2 as at least a constituent component, and the fusion beginning temperature (Tfb) of the toner has the relation of Tfb>Tmp with a melting point (Tmp) corresponding to the highest value of endothermic peaks belonging to the wax on an absorbed heat quantity curve in heating in the DSC curve of the toner measured with a differential scanning calorimeter. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic charge developing toner for visualizing an electrostatic charge latent image formed by an electrophotographic method, an electrostatic printing method, an electrostatic recording method and the like, and an image forming method.

[0002]

2. Description of the Related Art Among the above-mentioned printing or recording methods, for example, in the electrophotographic method, a photoconductive photosensitive member is charged and exposed,
An electrostatic latent image is formed on the photoconductor, and then the electrostatic latent image is developed with fine particle toner containing a colorant and the like using a resin as a binder, and the obtained toner image is transferred and fixed on a recording paper. A recorded image can be obtained.

In such an electrostatic image recording process, development of an electrostatic latent image with fine particle toner and fixing on a recording paper are particularly important processes. Conventionally, as a method of developing toner, high speed and high speed are used. A magnetic brush developing method using a two-component developer composed of a toner and a magnetic carrier capable of developing an image quality is often used. As a method for fixing the toner, a heat roller fixing method, which has high thermal efficiency and enables high-speed fixing, is often used.

On the other hand, recently, with the development of information equipment, a laser beam printer has been developed which uses a laser beam to expose a photoconductive photosensitive member and reproduces a recorded image in dots by a modulation signal instructed by a computer. There is.
Particularly, in recent laser beam printers, since it is required to produce images with higher image quality, the diameter of the laser beam is narrowed down to reduce the dot density to 600 to 1200d.
It is as high as pi (dots / inch). Along with this, for the purpose of developing a fine electrostatic latent image, the particle diameters of the toner and the carrier are also reduced, and the particle diameters of the fine particle toner having a volume average particle diameter of 10 μm or less and the fine particle carrier having a weight average particle diameter of 100 μm or less. Application is in progress.

On the other hand, the above-mentioned heat roller fixing is often used for fixing, but it is necessary to suppress overheat deterioration of the printer and prevent heat deterioration of parts inside the machine. Shorten the warm-up time from when the fixing machine is activated until fixing is possible. Also, prevent fixing failure due to heat being absorbed by the recording paper, and maintain image quality through continuous paper feeding. Prevent curling and fire of recording paper due to overheating. From the viewpoints of reducing the load applied to the heat roller and simplifying and downsizing the structure of the fixing device, the power consumption of the fixing heater and drive motor is reduced to keep the heat roller at a lower temperature and heat. It is desired to develop a toner that can fix the pressure of the roller at a lower pressure.

As described above, development of a high-performance toner capable of fixing fine particles with low temperature and low pressure is desired. On the other hand, when the toner is made into fine particles of 10 μm or less as described above, the following problems occur. That is, in the developing step, high image quality can be obtained by using fine particle toner, but toner adhesion (fogging) to the non-image area and toner scattering easily occur, and handling property such as toner transportation due to deterioration of fluidity is also obtained. Easy to fall. Furthermore, due to the strong adhesion of the fine particle toner and the low impact resistance, carrier contamination (carrier spent) by the toner is likely to occur and the life of the developer is likely to be shortened.

Further, in terms of fixing, in order to obtain the same fixing strength, more energy is required than that of a toner having a large particle size, and the yield in the pulverizing and classifying steps is lowered at the time of toner production, so the toner cost is low. Becomes higher. Many problems occur with fine particle toners, and the average particle size is usually 5
A toner having a particle size of less than μm is difficult to put into practical use, and the average particle size of the toner is classified into a range of 5 to 10 μm, and the fluidity of the toner is increased by improving the external additive and the external additive formulation of the toner. On the other hand, with respect to the carrier, the weight average particle size is reduced to 100 μm or less in accordance with the decrease in the particle size of the toner, and the specific surface area of the carrier is increased to improve the triboelectric chargeability with the toner. However, when the carrier is less than 30 μm, the magnetic force of the carrier is reduced and the carrier is easily attached to the electrostatic image holding member by electrostatic attraction force.
The particles are classified into a range of 0 μm, and the surface is coated with a resin if necessary.

Due to the improvement of the particle size distribution, the fluidity and the charging property, the fine particle toner and the developer have been put to practical use in a copying machine, a printer and the like. However, when printing with an actual machine, especially when high-speed printing of 10 pages per minute or more is repeated, the above-mentioned problems peculiar to the fine particle toner occur, the life of the developer is shortened due to the carrier spent by the toner, and the photoreceptor due to the toner is used. The life of the photoconductor is likely to decrease due to filming. In addition, it is difficult to obtain the fixing strength of the image, and in particular, it is necessary to increase the temperature and pressure of the heat roller in the fixing process.
There was a problem that it was difficult to reduce size and cost.

It is known to add wax to the fixing resin in order to improve the fixing performance of the toner. For example, the techniques disclosed in JP-A-52-3304, JP-A-52-3305, and JP-A-57-52574 are disclosed.

Waxes prevent the toner from adhering to the heat roller at low temperature or high temperature, that is, so-called offset phenomenon,
It is used to improve the fixability of toner at low temperatures, and recently, a low-melting wax has attracted attention from the viewpoint of low-temperature fixing.

For example, in JP-A-5-313413, in order to improve the low temperature fixing property, anti-offset property and non-aggregating property of a toner, a vinyl copolymer having a specific molecular weight distribution has a viscosity at 140 ° C. It is disclosed to add ethylene or propylene and an α-olefin copolymer of 10,000 poise or less.

For the same purpose, Japanese Patent Laid-Open No. 7-2874.
JP-A-8-314181, JP-A-9-179335, and JP-A-9-179335 disclose the addition of paraffin wax having a peak (melting point) of absorbed heat by a differential scanning calorimeter (DSC) of 75 to 85 ° C. In Japanese Patent Laid-Open No. 9-319139, a natural gas type Fischer-Tropish wax having a melting point of 85 to 100 ° C. by DSC is added, and in Japanese Patent Laid-Open No. 6-324513, the melting point by DSC is 8
Adding polyethylene wax at 5 to 110 ° C.,
Japanese Patent Laid-Open No. 7-36218 discloses a DSC having a melting point of 50 ° C. or lower, which is removed by a distillation method or the like to have a melting point of 70 to 1
It is disclosed that a polyethylene wax at 20 ° C. is added, and JP-A-8-114942 discloses that a polyethylene wax having a weight average molecular weight (Mw) of less than 1,000 is added.

On the other hand, when the low melting point wax is added to the toner, the heat resistance, durability and storage stability of the toner are lowered. In order to improve it, JP-A-6-123994 uses a wax having a weight average molecular weight / number average molecular weight (Mw / Mn) of 1.5 or less, and JP-A-7-209909 discloses a melt viscosity at 140 ° C. Use of an ethylene-based olefin polymer wax having a penetrability of 0.5 to 10 dPa and a penetration of 3.0 dmm or less.
Japanese Patent No. 87418 discloses that Fischer-Tropish wax having an average molecular weight of 1,000 or more is used.

Although it is possible to improve the fixing performance of the toner by using these conventional techniques, when the low melting point wax is used, especially in the case of fine particle toner, the heat resistance, durability and storage stability of the toner are maintained. It is difficult to improve the fixing performance in the above method, and it is impossible to provide a toner and an image forming method that can be put to practical use.

[0015]

The problem to be solved by the present invention is, in the above-described fine particle toner and image forming method, that the toner has good heat resistance, durability and storage stability, and the life of the developer due to carrier spent by the toner. Is less likely to occur, and the life of the photoconductor is less likely to decrease due to filming of the photoconductor with toner. Also, the energy required for fixing is small, and the temperature and pressure of the heat roller can be reduced when the heat roller fixing method is adopted. And to provide a toner in which an offset phenomenon does not easily occur, and to provide a stable electrostatic toner image forming method using the toner.

[0016]

The inventors of the present invention have conducted extensive studies to solve the above problems, and as a result, in an electrostatic charge developing toner containing at least a fixing resin and a wax, the fixing resin is at least 1 as its component
It contains a vinyl copolymer polymerized in the presence of a polyethylene wax having a melt viscosity at 40 ° C. of less than 10 mPa · s, the wax being a polyethylene wax, and having a melt viscosity at 140 ° C. of at least 10 mPa · s as its constituent component. As described above, a wax having a penetration of 2 or less is used, and the melting start temperature (Tfb) of the toner is a DSC curve measured by a differential scanning calorimeter of the toner. It was found that the melting point (Tmp) corresponding to the maximum value of the endothermic peaks assigned and the relationship of Tfb> Tmp are sufficient.

Further, in the toner of the present invention, the electrostatic latent image formed on the electrostatic charge holding member is visualized by using a two-component developer composed of toner and carrier, and the visualized toner image is formed. In the electrostatic image recording process of FIG. 1, the toner image transferred onto the recording medium is cleaned to remove the toner image remaining on the electrostatic charge holding member, and the transferred toner image is fixed onto the recording medium to obtain a recorded image. It has been shown to exhibit characteristics and provide a stable electrostatic toner image preparation method.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. Generally, vinyl-based copolymers, particularly styrene to (meth) acrylic resins, have been used as the fixing resin for the toner for fixing the heat roller, and recently, polyester-based resins have also been used. However, polyester-based resins generally have highly water-absorbing polar groups (hydroxyl groups, carboxyl groups), toner tends to absorb moisture, and the charging characteristics of the toner are liable to change. Is the mainstream toner for toner. Waxes are added to this fixing resin to improve the fixing performance of the toner.

Waxes have been generally used for a long time as an offset preventive agent for toners, but on the other hand, the fluidity, heat resistance, durability and storage stability of the toner are deteriorated and fusion is apt to occur. There is a problem to do. There are many kinds of waxes, and they are used properly according to their functions. From the viewpoint of preventing toner offset, polyethylene wax that is non-polar and non-adhesive to the heat roller is most suitable.

Polyethylene wax is an aggregate of polyethylene molecules having a molecular weight distribution, and its characteristics depend largely on the molecular weight distribution. In general, the effect of polyethylene wax is not only to prevent high temperature offset, but also to prevent low temperature offset and improve low temperature fixing by increasing the amount of low molecular weight components.

However, when the low molecular weight component is increased to improve the fixing performance, the heat resistance, the durability and the storage stability of the toner are lowered and the developer is apt to be fused to the carrier and the photoreceptor. . Therefore, it has been attempted to thoroughly cut the low molecular weight components of the existing polyethylene wax to make the molecular weight distribution sharp. That is, in the molecular weight distribution measurable by GPC, the molecular weight distribution of the wax is sharpened so that the weight average molecular weight / number average molecular weight (Mw / Mn) is 1.5 or less, preferably 1.45 or less.

However, according to the study by the present inventors, when the molecular weight distribution of the polyethylene wax is sharp as described above, the heat resistance, durability and storage stability of the toner are improved, but the fixing performance is insufficient. In particular, it was found that in the case of the fine particle toner, the fixing performance deteriorates when high-speed printing of 10 pages per minute or more is repeated.

Therefore, the present inventors have found that the melt viscosity at 140 ° C. containing a proper amount of low molecular weight component is 10 mPa ·
Paying attention to a polyethylene wax having a viscosity of less than s, a vinyl copolymer polymerized in the presence thereof is used as a fixing resin, and a wax having a melt viscosity at 140 ° C. of 10 mPa.
Use polyethylene wax with a penetration of 2 or more and a penetration of 2 or less,
The melting start temperature (Tfb) of the toner is a melting point (Tfb) corresponding to the maximum value of the endothermic peak attributed to the wax in the absorption calorific curve at the time of temperature rise in the DSC curve measured by a differential scanning calorimeter of the toner. Tmp) and Tfb> Tmp,
It was found that the toner fixing performance was sufficiently obtained. In addition, the fluidity, heat resistance, durability, and storage stability of the toner are good, and the life of the developer is shortened due to the carrier spent by the toner, and the life of the photoconductor is less likely to be deteriorated due to the filming of the photoconductor by the toner. It was found that the electrostatic toner image forming method described above can be provided.

In the present invention, a low-viscosity polyethylene wax having a melt viscosity at 140 ° C. of less than 10 mPa · s is used. However, when such a low-viscosity polyethylene wax is added to the toner, the hardness of the wax is small. Unless the dispersibility of the wax in the toner is improved, the fluidity, heat resistance, durability and storage stability of the toner cannot be secured. As a method of improving the dispersibility of the wax in the toner, there is a method of increasing the energy at the time of melt-kneading the toner to finely disperse the wax in the fixing resin. However, in this method, while the dispersibility of the wax is improved, the fixing resin is mechanically damaged, and the fixing property and the high temperature offset resistance are deteriorated.

Then, as another kind of method for improving the dispersibility of wax, JP-A-5-313413 and JP-A-9-134413 are available.
-281748 and JP-A-9-304966, there is a coexisting polymerization method in which a wax is allowed to coexist in the whole or a part of the process of synthesizing a fixing resin. Was uniformly dispersed in the fixing resin without deterioration of the resin. When the fixing resin of the present method is applied to a toner, the fluidity, heat resistance, durability, and storage stability of the toner are improved, the carrier life of the toner shortens the life of the developer, and the photoreceptor of the toner It was found that the life of the photoconductor is less likely to decrease due to filming and a stable electrostatic toner image production method can be provided.

However, in this method, although the fluidity, heat resistance, durability and storage stability of the toner are improved, as the wax resin and the dispersibility in the toner are improved, the toner is fixed at the time of fixing. The wax becomes difficult to elute, and the offset resistance decreases. In order to prevent this decrease in offset resistance, in the present invention, a high viscosity having a melt viscosity at 140 ° C. of 10 mPa · s or more and a penetration of 2 or less,
Focusing on high-hardness polyethylene wax, we examined the addition of the above wax to co-polymerized resin and found that it improved offset resistance without impairing the fluidity, heat resistance, durability, and storage stability of the toner. I was able to get it. Also,
In the toner obtained with such a resin system, the melting start temperature (Tfb) of the toner is attributed to the wax of the absorption heat quantity curve at the time of temperature rise in the DSC curve measured by a differential scanning calorimeter of the toner. Fixing resin, so that the melting point (Tmp) corresponding to the maximum value of the endothermic peak and Tfb> Tmp
It has been found that when a wax mixture system is selected, adverse effects on the fixing strength of the above-mentioned high-viscosity, high-hardness polyethylene wax added as an offset preventive agent are reduced and sufficient fixing strength can be obtained.

In the present invention, the melting start temperature (T
For fb), the outflow starting temperature is measured from the flow process of the piston stroke shown in FIG. 2 by the temperature raising method using a constant load extrusion type thin tube type rheometer (flow tester CFT-500C type manufactured by Shimadzu Corporation), and is taken as Tfb. At this time, the measurement conditions of the flow tester were a load of 20 kgf / cm ² , a die diameter of 1 mm, a die length of 10 mm, and a heating rate of 6 ° C./min.

On the other hand, the melt viscosity of the wax is measured at 140 ° C. using a Brookfield viscometer. The penetration of wax is JIS K2 at room temperature.
According to the present invention, the toner has a melt viscosity at 140 ° C. of less than 10 mPa · s and a low viscosity polyethylene wax of the present invention generally has a value of more than 2.

In the DSC measurement, the heat exchange of the toner is measured and the behavior thereof is observed. Therefore, it is preferable to use a heat flux type differential scanning calorimeter having an extremely high sensitivity from the measurement principle.
For example, 2910 manufactured by TA Instruments can be used. The measurement conditions are as follows: About 5 mg of toner is placed on the DSC, and 50 ml of nitrogen gas is blown into the DSC for 20 minutes.
C. to 150.degree. C. is heated at a rate of 10.degree. C. per minute, then rapidly cooled from 150.degree. C. to 20.degree. C., after taking a previous history, the temperature is again raised at a rate of 10.degree. C. per minute. At that time, the melting point (Tmp) corresponding to the maximum value of the endothermic peak attributed to the wax and / or the wax of the DSC absorption calorific curve shown in FIG. 3 is determined.

In the toner of the present invention, the amount of polyethylene wax added is preferably 0.5 to 20 wt% with respect to the fixing resin in the total amount of low-viscosity and / or high-viscosity wax. If it is less than 0.5% by weight, the effect of improving the fixing performance of the toner becomes small, and if it exceeds 20% by weight, the high temperature offset of the toner tends to occur. Further, other waxes may be used in combination, but they must be used with care so that the performance of the polyethylene wax of the present invention is not impaired.

The vinyl-based copolymer used in the fixing resin of the present invention contains a styrene-based monomer and / or a (meth) acrylic acid ester-based monomer as its constitutional unit, and other than this. A vinyl-based monomer may be included.

Specific examples of the styrene-based monomer in the present invention include o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-ethylstyrene, 2,4-, in addition to styrene. Dimethyl styrene, p
-N-butylstyrene, p-ter-butylstyrene, pn
-Hexyl styrene, pn-octyl styrene, pn-
Dodecyl styrene, p-methoxy styrene, p-phenyl styrene, p-crawler styrene, 3,4-di crawler styrene and the like can be mentioned.

Specific examples of the acrylic acid ester or methacrylic acid ester monomer in the present invention include methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, n-octyl acrylate, Dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-methacrylate In addition to alkyl esters of acrylic acid or methacrylic acid such as ethylhexyl and stearyl methacrylate, 2-crawlerethyl acrylate, phenyl acrylate, α-crawler methyl acrylate, phenyl methacrylate, methacrylic acid, etc. Examples thereof include dimethylaminoethyl acid ester, diethylaminoethyl methacrylate, 2-hydroxyethyl methacrylate, glycidyl methacrylate, bisglycidyl methacrylate, polyethylene glycol dimethacrylate, methacryloxyethyl phosphate, etc., ethyl acrylate, propyl acrylate, Butyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate and the like are particularly preferably used.

Other vinyl monomers in the present invention include acrylic acid such as acrylic acid, methacrylic acid, α-ethylacrylic acid and crotonic acid and / or its α- or β-alkyl derivative, fumaric acid, maleic acid. Unsaturated dicarboxylic acids such as citraconic acid and itaconic acid and their monoester derivatives and diester derivatives, succinic acid monoacryloyloxyethyl ester, succinic acid monomethacryloyloxyethyl ester, acrylonitrile, methacrylonitrile, acrylamide, etc. .

The fixing resin in the present invention can be made uniform by using these vinyl monomers and carrying out the coexisting polymerization in which the polyethylene wax of the present invention coexists in all or a part of the synthesis. It is possible to obtain the vinyl-based copolymer dispersed in at least as its constituent element. The vinyl-based copolymer is mainly 2
Crosslinking of monomers having one or more polymerizable double bonds, such as divinylbenzene, divinylnaphthalene, ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, divinylaniline, divinyl ether, divinyl sulfide, divinyl sulfone The agent may be partially crosslinked.

The charge amount of the toner can be controlled to a desired value by blending (internally adding) or mixing (externally adding) a charge control agent to the toner particles in the toner of the present invention.

As the positive charge control agent for the toner, nigrosine and its modified products with fatty acids and the like; quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonic acid and tetrabutylammonium tetrafluoroborate, and these An onium salt such as a phosphonium salt and a lake pigment thereof, a triphenylmethane dye and a lake pigment thereof, which are analogs of
Metal salts of higher fatty acids; diorganotin oxides such as dibutyltin oxide, dioctyltin oxide, dicyclohexyltin oxide; diorganotin borates such as dibutyltin borate, dioctyltin borate, dicyclohexyltin borate; these alone or in combination of two or more Can be used.
Among these, nigrosine, quaternary ammonium salts,
Charge control agents such as triphenylmethane dyes are particularly preferably used.

As the negative charge control agent for the toner, organic metal complexes and chelate compounds are effective, and there are monoazo metal complexes, acetylacetone metal complexes, aromatic hydroxycarboxylic acids and aromatic dicarboxylic acid type metal complexes.
Others include aromatic hydroxycarboxylic acids, aromatic mono- and polycarboxylic acids and their metal salts, anhydrides, esters, and phenol derivatives such as bisphenol.

When these charge control agents are internally added to the toner, it is preferable to add them in an amount of 0.1 to 10 wt% with respect to the fixing resin.

In the toner of the present invention, it is preferable to externally add fine silica powder in order to improve developability, fluidity, charge stability and durability.

The fine silica powder used in the present invention is BET.
It is preferable that the specific surface area by nitrogen adsorption measured by the method is 30 m ² / g or more, and it is externally added in the range of 0.01 to 5 wt% with respect to the toner. Further, if necessary, the silica fine powder is used by treating it with a treating agent such as various organic silicon compounds or various treating agents to make it hydrophobic or controlling the chargeability.

Further, as other additives to the toner, lubricant powders such as Teflon (registered trademark) resin powder, zinc stearate powder, polyvinylidene fluoride powder, and polyvinylidene fluoride are preferable. Alternatively, abrasives such as cerium oxide powder, silicon carbide powder, and strontium titanate powder, among which strontium titanate is preferable.
Alternatively, a fluidity-imparting agent such as titanium oxide powder and aluminum oxide powder, and particularly hydrophobic ones are preferable. Anti-agglomeration agent, or carbon black powder,
A small amount of conductivity enhancers such as zinc oxide powder, antimony oxide powder and tin oxide powder, and white particles and black particles having opposite polarities can be used as a developing property improver.

The toner of the present invention is used as a mixture with a carrier when used as a two-component developer. In this case, the mixing ratio of the toner and the carrier is preferably 2 to 10 wt% as the toner concentration.

As the carrier that can be used in the present invention, known carriers can be used. For example, iron powder, ferrite, magnetite, glass beads and the surface thereof are coated with a fluorine resin, a vinyl resin or a silicone resin. What is done is used.

The toner of the present invention is usually used as a two-component developer comprising a toner and a carrier, but a magnetic material may be further added to the toner to be used as a magnetic toner as a one-component developer. In this case, the magnetic material can also serve as a coloring agent. In the present invention, the magnetic material contained in the magnetic toner includes magnetite, hematite and iron oxide of ferrite; metals such as iron, cobalt and nickel, or aluminum of these metals such as aluminum, cobalt, copper, lead, magnesium and tin, Zinc, antimony,
Included are alloys with metals such as calcium, manganese, selenium, titanium, tungsten, vanadium and mixtures thereof.

These magnetic materials have an average particle size of 2 μm or less, preferably about 0.1 to 0.5 μm, and the amount contained in the toner is 30 with respect to the fixing resin.
~ 70wt% is good.

Colorants that can be used in the toner of the present invention include any suitable pigments or dyes. Examples of the colorant for toner include pigments such as carbon black, aniline black, acetylene black, naphthol yellow, hansa yellow, rhodamine lake, alizarin lake, red iron oxide, phthalocyanine blue, and indanthrene blue. These are used in an amount necessary and sufficient for maintaining the optical density of the fixed image, and preferably 0.2 to 15 wt% is added to the resin.

Further, a dye is used for the same purpose. For example, there are azo type dyes, anthraquinone type dyes, xanthene type dyes, and methine type dyes.
~ 15 wt% is added.

To prepare the toner for electrostatic charge development in the present invention, a fixing resin in which the aforementioned low-viscosity wax is uniformly dispersed by co-polymerization, a high-viscosity wax, a charge control agent,
A pigment or dye as a colorant, magnetic powder, and optionally other waxes and additives are sufficiently mixed by a mixer such as a Henschel mixer or a super mixer, and then hot-melt kneading such as a heating roller, a kneader or an extruder. After melting and kneading using a machine to sufficiently mix the materials,
After solidification by cooling, fine pulverization and classification are performed to obtain an average particle size of 5 to 10
To obtain a toner of μm. Further, if desired, a desired additive may be adhered and mixed on the surface of the toner with a mixer such as a Henschel mixer to obtain a toner to which the additive is externally added.

In the toner of the present invention, the electrostatic latent image formed on the electrostatic charge holding member is visualized using a two-component developer composed of toner and carrier, and the visualized toner image is recorded on the recording medium. It shows particularly good fixing performance in the electrostatic image recording process in which the toner image transferred onto the electrostatic charge holding member is cleaned and the transferred toner image is fixed onto the recording medium to obtain a recorded image. Also, the fluidity, heat resistance, durability, and storage stability of the toner are good, and the life of the developer is shortened by the carrier spent by the toner and the life of the photoconductor is less likely to be reduced by the filming of the photoconductor by the toner.
It is possible to provide a stable electrostatic toner image production method.

Examples of the present invention will be described below, but the present invention is not limited thereto. (Example 1) 70 parts by weight of styrene, 10 parts by weight of methyl methacrylate and 20 parts by weight of n-butyl acrylate were polymerized to obtain a resin having a maximum molecular weight distribution of about 400,000. A mixture of 200 g of this resin and 45 g of low-viscosity polyethylene wax (trade name: Neowax AL manufactured by Yasuhara Chemical Co., Ltd.) was placed in a 3 liter separable flask and dissolved with 1 liter of xylene, and the gas phase was replaced with nitrogen gas. The system was heated to the boiling point of xylene (135-145 ° C).

A mixture of 440 g of styrene, 65 g of n-butyl acrylate and 30 g of t-butylperoxy 2-ethylhexanoate as a polymerization initiator was stirred for 2.5 hours while stirring under reflux of xylene. Solution polymerization was carried out while dropping, and a low molecular weight polymer component was polymerized in the presence of the high molecular weight polymer and polyethylene wax. After completion of dropping, the mixture was aged for 1 hour while stirring at the boiling temperature of xylene. Then set the system temperature to 1
While gradually raising the temperature to 80 ° C., the xylene was removed under reduced pressure to obtain a resin HT-1 having a molecular weight distribution peak on the low molecular weight side of about 45,500.

In this resin HT-1, the content of the low-viscosity polyethylene wax was about 6 wt%, and the wax was a purified product of a low-polymerized polyethylene of the medium and low pressure method.
The melt viscosity at 0 ° C. is 8.5 mPa · s, and the penetration at room temperature is 5.3.

Next, styrene-acrylic copolymer resin HT-1 89 wt% containing low viscosity polyethylene wax
%, 2 wt% of a high hardness polyethylene wax (PW1000 80M manufactured by Toyo Petrolite Co., Ltd.) having a melt viscosity at 140 ° C. of 13.7 mPa · s and a penetration at room temperature of 1.1.
Chromium metal dye (Product name: Orient Chemical Industry Co., Ltd .:
A toner raw material consisting of 1 wt% of Bontron S-34) and 8 wt% of carbon black (trade name: MA-100, manufactured by Mitsubishi Chemical Co., Ltd.) is premixed with a super mixer, hot-melt kneaded with a twin-screw kneader, and then jet-milled. And finely pulverized with a dry air classifier to obtain toner particles having an average particle size of about 9 μm. Further, 0.8 wt% of hydrophobic silica (Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.) was added to the particles and stirred with a Henschel mixer to adhere the hydrophobic silica to the surface of the particles to obtain the toner of the present invention. Toner melting temperature (T
fb) was 104 ° C., and the melting point (Tmp) of the wax component of the toner corresponding to the maximum value of the heat absorption curve in DSC was 84 ° C.

The above toner is applied to an electrophotographic laser beam printer using OPC as a photoconductor, and the charging potential of OPC is −650 V, the residual potential is −50 V, the developing bias potential is −400 V, and the developing section contrast potential is 350 V. Minute 6
Images were produced at a printing speed of 0 sheets (printing process speed 26.7 cm / sec). In the developing machine, the carrier has a weight average particle diameter of 10 coated with a conductive agent-containing silicone resin.
0 μm magnetite carrier (electrical resistance 4.1 × 10 ⁸
Ω · cm) and a toner concentration of 2.5 wt% to prepare a developer, and a magnetic brush developing method to set the developing gap (distance between the photoconductor and the developing roller sleeve) to 0.8 mm. In the same direction, and the peripheral speed ratio (developing roller /
An image was prepared by reversal development using a photoconductor of 3. The fixing device is a heat roller that is made by coating a thin aluminum cored bar with a fluororesin (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer: PFA) tube (thickness 40 μm) and installing a heater lamp in the center. And a silicone rubber layer with a rubber hardness of about 30 degrees on an aluminum core
(Thickness 7 mm) is installed and the outermost layer is covered with PFA tube as a backup roller. Fixing conditions are process speed 26.7 cm / sec, heat roller and backup roller outer diameter 60 mm, pressing load 50 kgf, both. Contact area
The width of the (nip) is about 7 mm and the control temperature of the heat roller is 18
The temperature was 5 ° C. A Nomex paper winding type cleaning machine impregnated with silicone oil was installed on the heat roller.

Regarding the storage stability of the above-mentioned toner, the toner was put in a metal Petri dish and left standing for 24 hours at 50 ° C. in a desiccator in which the humidity was controlled to 91% RH with a humidity adjuster, and the degree of toner aggregation was visually observed. evaluated. As a result, the toner did not cause noticeable aggregation, and the storage stability was good.
Further, when it was applied to the above laser beam printer and continuous printing was performed, good fixing performance was obtained, and even when continuous printing of 300,000 pages was repeated, the life of the developer was shortened due to carrier spent due to toner, and due to toner, It was possible to obtain a stable image without causing a decrease in the life of the photoconductor due to filming of the photoconductor. (Example 2) As a high hardness polyethylene wax, 14
Melt viscosity at 0 ° C is 11.1 mPa · s and penetration is 1.
A toner of the present invention was obtained in the same manner as in Example 1 except that Fischer-Tropish wax (MDP 7000 manufactured by Nippon Seiro Co., Ltd.) synthesized from natural gas No. 7 was used. The melting temperature of the toner (Tfb) is 102 ° C, and the melting point corresponding to the maximum value of the heat absorption curve in the DSC of the wax component of the toner.
(Tmp) was 84 ° C. The toner was evaluated in the same manner as in Example 1, and as a result, good results were obtained as in Example 1. (Example 3) As a high hardness polyethylene wax, 14
Melt viscosity at 0 ° C is 11.7 mPa · s and penetration is 1.
Example 1 except that Fischer-Tropish wax (SPRAY105 manufactured by Sazol Co.) synthesized from coal No. 8 was used.
A toner of the present invention was obtained in the same manner as in. The melting start temperature (Tfb) of the toner is 103 ° C., and the melting point (Tmp) corresponding to the maximum value of the absorbed heat quantity curve in the DSC of the wax component of the toner is 8
It was 4 ° C.

The toner was evaluated in the same manner as in Example 1, and as a result, good results were obtained as in Example 1. (Comparative Example 1) 70 parts by weight of styrene, 10 parts by weight of methyl methacrylate and 20 parts by weight of n-butyl acrylate were polymerized to obtain a resin having a maximum molecular weight distribution of about 450,000. A mixture of 200 g of this resin and 23 g of low-viscosity polyethylene wax (trade name: Neowax AL, manufactured by Yasuhara Chemical Co., Ltd.) was placed in a 3 liter separable flask and dissolved with 1 liter of xylene, and the gas phase was replaced with nitrogen gas. The system was heated to the boiling point of xylene (135-145 ° C).

A mixture of 440 g of styrene, 65 g of n-butyl acrylate and 30 g of t-butylperoxy 2-ethylhexanoate as a polymerization initiator was stirred for 2.5 hours while stirring under reflux of xylene. Solution polymerization was carried out while dropping, and a low molecular weight polymer component was polymerized in the presence of the high molecular weight polymer and polyethylene wax. After completion of dropping, the mixture was aged for 1 hour while stirring at the boiling temperature of xylene. Then set the system temperature to 1
While gradually raising the temperature to 80 ° C., the xylene was removed under reduced pressure to obtain a resin HT-2 having a molecular weight distribution peak on the low molecular weight side of about 45,500.

In this resin HT-2, the content of the low-viscosity polyethylene wax was about 3 wt%, and the wax was a refined product of a low-polymerized polyethylene of the medium and low pressure method.
The melt viscosity at 0 ° C. is 8.5 mPa · s, and the penetration at room temperature is 5.3.

Next, styrene-acrylic copolymer resin HT-2 86 wt containing low viscosity polyethylene wax.
%, 5 wt% of high hardness polyethylene wax (PW1000 80M manufactured by Toyo Petrolite Co., Ltd.) having a melt viscosity at 140 ° C. of 13.7 mPa · s and a penetration at room temperature of 1.1.
Chromium metal dye (Product name: Orient Chemical Industry Co., Ltd .:
A toner raw material consisting of 1 wt% of Bontron S-34) and 8 wt% of carbon black (trade name: MA-100, manufactured by Mitsubishi Chemical Co., Ltd.) is premixed with a super mixer, hot-melt kneaded with a twin-screw kneader, and then jet-milled. And finely pulverized with a dry air classifier to obtain toner particles having an average particle size of about 9 μm. Further, 0.8 wt% of hydrophobic silica (Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.) was added to the particles and stirred with a Henschel mixer to adhere the hydrophobic silica to the surface of the particles to obtain the toner of the present invention. Toner melting temperature (T
fb) was 106 ° C., and the melting point (Tmp) of the wax component of the toner corresponding to the maximum value of the absorbed heat curve in DSC was 109 ° C.

Regarding the storage stability of the above-mentioned toner, the toner was put in a metal Petri dish and left in a desiccator in which the humidity was controlled to 91% RH with a humidity control agent at 50 ° C. for 24 hours to visually observe the degree of aggregation of the toner. evaluated. As a result, the toner did not cause noticeable aggregation, and the storage stability was good.
On the other hand, the first embodiment is applied to the above laser beam printer.
When evaluated in the same manner as above, the life of the developer was not shortened by the carrier spent by the toner and the life of the photoreceptor was shortened by the filming of the photoreceptor by the toner even when continuous printing was repeated, but sufficient fixing strength was obtained. No
No good image quality could be obtained. (Comparative Example 2) As a high hardness polyethylene wax, 14
Melt viscosity at 0 ° C is 11.7 mPa · s and penetration is 1.
Comparative Example 1 except that Fischer-Tropish wax synthesized from coal of No. 8 (SPRAY105 manufactured by Sazol Co.) was used.
A toner of the present invention was obtained in the same manner as in. The melting start temperature (Tfb) of the toner is 105 ° C., and the melting point (Tmp) corresponding to the maximum value of the heat absorption curve in the DSC of the wax component of the toner is 1
It was 07 degreeC.

The toner was evaluated in the same manner as in Comparative Example 1, and the same results as in Comparative Example 1 were obtained.

[0063]

As described above, according to the present invention, the fluidity, heat resistance, durability and storage stability of the fine particle toner are good, the life of the developer is shortened by the carrier spent by the toner, and the photosensitivity by the toner is improved. The life of the photoconductor is less likely to decrease due to body filming, the energy required for fixing is small, and the temperature and pressure of the heat roller can be reduced when the heat roller fixing method is adopted, and
It is possible to provide the toner in which the offset phenomenon does not easily occur.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an electrostatic recording process.

FIG. 2 is an explanatory view showing an example of measurement of a melting start temperature by a constant load extrusion type capillary rheometer.

FIG. 3 is an explanatory diagram showing an example of measuring a melting point by a DSC absorption calorie curve.

[Explanation of symbols]

1 charger 2 photoconductor 3 exposure device 4 developing roller 5 Developer 6 recording media 7 Transfer device 8 Fixing heat roller 9 Backup roller for fixing 10 Erase light source 11 cleaning machine

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shigenori Taniguchi             Hitachiko, 1060 Takeda, Hitachinaka City, Ibaraki Prefecture             Machine Co., Ltd. (72) Inventor Junji Kobayashi             Hitachiko, 1060 Takeda, Hitachinaka City, Ibaraki Prefecture             Machine Co., Ltd. (72) Inventor Tadahiro Kaneko             Hitachiko, 1060 Takeda, Hitachinaka City, Ibaraki Prefecture             Machine Co., Ltd. (72) Inventor Hoshi Nobuyoshi             Hitachiko, 1060 Takeda, Hitachinaka City, Ibaraki Prefecture             Machine Co., Ltd. F-term (reference) 2H005 AA01 AA06 CA02 CA13 CA14                       EA03

Claims (2)

[Claims] 1. In an electrostatic charge developing toner containing at least a fixing resin and a wax, the fixing resin has a melt viscosity at 140 ° C. of at least 1 as a constituent component thereof.
It contains a vinyl copolymer polymerized in the presence of a polyethylene wax of less than 0 mPa · s, and the wax is a polyethylene wax, and at least its constituent component has a melt viscosity at 140 ° C. of 10 mPa · s or more and a penetration of 2 The following wax is contained, and the melting start temperature of the toner
(Tfb) is the melting point (Tm) corresponding to the maximum value of the endothermic peak attributed to the wax in the absorption calorific curve at the time of temperature rise in the DSC curve measured by a differential scanning calorimeter of the toner.
p) and Tfb> Tmp. 2. An electrostatic latent image formed on an electrostatic charge holding member is visualized by using a two-component developer composed of toner and carrier, and the visualized toner image is transferred onto a recording medium. In the electrostatic image recording step of cleaning the toner image remaining on the electrostatic charge holding member and fixing the toner image transferred onto the recording medium to obtain a recorded image, the toner contains at least fixing resin and wax. An electrostatic charge developing toner containing the fixing resin, wherein the fixing resin contains, as at least a component thereof, a vinyl-based copolymer polymerized in the presence of a polyethylene wax having a melt viscosity at 140 ° C. of less than 10 mPa · s. Is a polyethylene wax, which contains at least a wax having a melt viscosity at 140 ° C. of 10 mPa · s or more and a penetration of 2 or less as a constituent component thereof, The melting start temperature (Tfb) is the melting point (Tmp) corresponding to the maximum value of the endothermic peak attributed to the wax in the absorption calorific curve at the time of temperature rise in the DSC curve measured by a differential scanning calorimeter of the toner. An image producing method characterized by having a relationship of Tfb> Tmp.