JP2000338717A - Electrostatic charge image developing toner and image forming device using same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance fluidity, heat resistance, durability and shelf stability and to reduce energy necessary for fixation by incorporating a vinyl copolymer polymerized in the presence of a polyethylene wax obtained by purifying a low grade polymer of polyethylene obtained by a medium or low pressure method into a fixing resin. SOLUTION: A vinyl copolymer polymerized in the presence of a polyethylene wax obtained by purifying a low grade polymer of polyethylene obtained by a medium or low pressure polyethylene polymerization method using a Ziegler catalyst or the like is incorporated into the fixing resin of an electrostatic charge image developing toner. Though the molecular weight distribution of the polyethylene wax is extended by moderately incorporating a low molecular weight component, in order to ensure satisfactory fixability and anti-offsetting property, the molecular weight distribution must be controlled in such a way that the melt viscosity of the polyethylene wax at 140 deg.C is reduced to <10 mPa.s.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic developing toner for visualizing an electrostatic latent image formed by electrophotography, electrostatic printing, electrostatic recording, and the like, and image formation using the same. It concerns the device.

[0002]

2. Description of the Related Art In an electrophotographic method, an electrostatic printing method, or an electrostatic recording method, for example, in an electrophotographic method, the surface of a photoconductive photoreceptor serving as an electrostatic charge holding member is charged and exposed to light, and An electrostatic latent image is formed, and then the electrostatic latent image is developed with a particulate toner containing a coloring agent or the like using a resin as a binder, and the obtained toner image is transferred onto a recording medium such as paper. After fixing, a recorded image is obtained.

[0003] In such an electrostatic image recording process, development of an electrostatic latent image with fine-grain toner and fixing on a recording medium are particularly important processes. Magnetic brush development using a two-component developer composed of a simple toner and a magnetic carrier is often used.
As a fixing method, a heat roller fixing method that has high thermal efficiency and can perform high-speed fixing is often used.

On the other hand, recently, with the development of information equipment,
2. Description of the Related Art A laser beam printer that uses a laser beam for exposing a photoconductive photoreceptor and reproduces a recorded image with dots by a modulation signal instructed by a computer has been developed. In particular,
In recent laser beam printers, even higher-quality image recording is required. Therefore, the diameter of the laser beam is reduced to be smaller, and the dot density is 600 to 1200 dpi.
(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 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 are used. Application is in progress.

[0005] On the other hand, the above-mentioned heat roller fixing is frequently used in fixing, but it is necessary to suppress overheating deterioration of the printer and prevent heat deterioration of components in the machine. To shorten the warm-up time from when the fixing device is activated to when fixing is possible. Further, it is possible to prevent a fixing failure due to heat absorption in a recording medium and to maintain image quality by continuous paper passing. Prevent curling of recording media and fire due to overheating. From the viewpoint of reducing the load applied to the heat roller and simplifying and reducing the size of the fixing device, the power consumption of the fixing heater and the driving motor is reduced, and the temperature of the heat roller is lowered. 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 which can be fixed at a low temperature and a low pressure with fine particles is desired.

On the other hand, when the toner is finely divided to 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 the fine particle toner, but toner adhesion (fogging) to the non-image area and toner scattering are liable to occur, and handling properties such as toner conveyance due to reduced fluidity are also improved. Easy to fall.

Further, due to the strength of the adhesion of the fine particle toner and the low impact resistance, carrier contamination (carrier spent) by the toner is apt to occur, and the life of the developer tends to be shortened.

In addition, in order to obtain the same fixing strength, more energy is required for toner having a large particle diameter than for toner having a large particle diameter, and the yield in the pulverization and classification steps is reduced during toner production. Get higher. Many problems occur in the fine particle toner, and it is usually difficult to put the toner smaller than 5 μm into practical use. The average particle diameter of the toner is classified into the range of 6 μm to 10 μm, and the external additives and the external additive formulation of the toner are improved. Used with increased fluidity of the toner. On the other hand, as for the carrier, as the particle size of the toner is reduced, the weight average particle size is reduced to 100 μm or less, the specific surface area of the carrier is increased, and the triboelectric charging property with the toner is improved. However, in the case of a carrier having a particle diameter of less than 40 μm, the magnetic force of the carrier is reduced and the carrier is easily attached to the electrostatic image holding member by electrostatic attraction.
The particles are classified into a range of μm, and the surface is coated with a resin if necessary.

Due to these improvements in particle size distribution, flowability and chargeability, fine particle toners and developers have come into practical use in image forming apparatuses such as copiers and printers. However, when high-speed printing of 10 pages or more per minute is repeated, problems peculiar to the fine particle toner occur, and the life of the developer is shortened by carrier spent by the toner, and the life of the photoconductor is shortened by filming of the photoconductor by the toner. It will be easier. Further, it is difficult to obtain the fixing strength of the image, and particularly, it is necessary to increase the temperature and the pressure of the heat roller in the fixing process, so that there is a problem that it is difficult to increase the reliability, simplify the size, and reduce the cost of the fixing device.

[0010] To improve the fixing performance of the toner, adding a wax to the fixing resin is disclosed in, for example, JP-A-52-330.
No. 4, JP-A-52-3305 and JP-A-5-3305.
It is known from, for example, JP-A-7-52574. Waxes are used to prevent toner from adhering to a heat roller at low or high temperatures, so-called offset phenomenon, and to improve the fixability of toner at low temperatures. Is attracting attention.

For example, JP-A-5-313413 discloses that a vinyl copolymer having a specific molecular weight distribution has a viscosity at 140 ° C. in order to improve the low-temperature fixability, anti-offset property and non-aggregation property of toner. It is disclosed that up to 10,000 poises of ethylene or propylene and an α-olefin copolymer are added.

For the same purpose, Japanese Patent Application Laid-Open No. 7-2874
JP-A No. 8-314181 and JP-A No. 9-179335 may add paraffin wax having a peak (melting point) of heat absorption of 75 ° C. to 85 ° C. by a differential scanning calorimeter (DSC). And Japanese Patent Application Laid-Open No. 9-3
No. 19139 discloses that the melting point by DSC is 85 ° C. to 10 ° C.
It is disclosed that a natural gas-based Fischer-Tropsch wax at 0 ° C. is added, and that a polyethylene wax having a melting point of 85 ° C. to 110 ° C. by DSC is added in JP-A-6-324513.

Japanese Patent Application Laid-Open No. 7-36218 discloses DS in which components having a melting point of 50 ° C. or less are removed by a distillation method or the like.
It is disclosed that a polyethylene wax having a melting point of 70 to 120 ° C. of C is added, and that a polyethylene wax having a weight average molecular weight (Mw) of less than 1,000 is added in JP-A-8-114942. .

On the other hand, when a low-melting wax is added to the toner, the heat resistance, durability and storage stability of the toner decrease. In order to improve this, a wax having a weight average molecular weight / number average molecular weight (Mw / Mn) of 1.5 or less is used in JP-A-6-123994, and a melt viscosity at 140 ° C. in JP-A-7-209909 is used. 0.5mPa · s-10
using an ethylene-based olefin polymer wax having a mPa · s and a penetration of 3.0 dmm or less;
JP-A-7-287418 discloses the use of Fischer-Tropsch wax having an average molecular weight of 1,000 or more.

[0015]

It is possible to improve the fixing performance of the toner by using the above-mentioned prior art. However, when a low melting point wax is used, especially for a fine particle toner, the fluidity, heat resistance and durability of the toner are reduced. Further, it is difficult to improve the fixing performance while maintaining the storage stability, and it has not been possible to provide a toner and an image forming apparatus that can be put to practical use.

An object of the present invention is to provide a toner which is excellent in fluidity, heat resistance, durability and storage stability, and which can reduce the energy required for fixing, and an image forming apparatus using the same. It is in.

[0017]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrostatic charge developing toner including a fixing resin and a wax.
The fixing resin is achieved by obtaining a toner for electrostatic charge development containing a vinyl-based copolymer polymerized in the presence of a polyethylene wax obtained by purifying a low-polymer of low- to medium-pressure polyethylene.

Further, the fixing resin contains a vinyl copolymer which is mainly composed of a fixing resin and a colorant, and wherein the fixing resin contains a vinyl copolymer which is polymerized in the presence of a polyethylene wax obtained by purifying a low polymer of a medium to low pressure method polyethylene. Developing means for supplying the charge developing toner to the electrostatic charge holding member holding the electrostatic latent image, and developing the electrostatic charge latent image as a toner image; and a toner image formed on the electrostatic charge holding member. This is achieved by obtaining an image forming apparatus having a transfer unit that transfers the toner image onto a recording medium and a fixing unit that applies at least heat to the recording medium holding the toner image and fixes the toner image on the recording medium.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail.

In general, a vinyl-based copolymer, particularly a styrene- (meth) acryl-based resin, is used as a fixing resin for a toner for fixing with a heat roller, and a polyester-based resin has recently been used. However, polyester resins generally have a highly water-absorbing polar group (hydroxyl group, carboxyl group), so that the toner tends to absorb moisture, and the charging characteristics of the toner are easily changed.
Acrylic resins are the mainstream of toner resins. A wax is added to the fixing resin to improve the fixing performance of the toner.

[0021] Waxes have long been used as an anti-offset agent for toners for a long time. However, on the other hand, the heat resistance, durability, and storage stability of the toner are lowered, and fusing tends to occur. There is. There are many types of waxes, which can be used depending on their functions. From the viewpoint of preventing toner offset, a non-polar, non-adhesive polyethylene wax for a heat roller is optimal.

Polyethylene wax is an aggregate of polyethylene molecules having a molecular weight distribution, and its characteristics largely depend on the molecular weight distribution. In general, the effect of polyethylene wax is effective not only in preventing high-temperature offset, but also in preventing low-temperature offset and improving 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, durability, and storage stability of the toner are reduced, and the developer is likely to be fused to the carrier and the photoreceptor. . Therefore, attempts have been made to thoroughly cut low molecular weight components of existing polyethylene waxes to sharpen the molecular weight distribution. That is, in the molecular weight distribution that can be measured by gel permeation chromatography (GPC), the molecular weight distribution of the wax is adjusted so that the weight average molecular weight / number average molecular weight (Mw / Mn) becomes 1.5 or less, preferably 1.45 or less. Sharpen.

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

Therefore, the present inventors made it possible to appropriately contain low molecular weight components, and to obtain a weight average molecular weight / number average molecular weight (Mw / M
As a result of applying a polyethylene wax having n) greater than 1.5 to the toner and evaluating various properties, the melt viscosity at 140 ° C. was less than 10 mPa · s, and the DSC curve measured by a differential scanning calorimeter showed an increase. The melting point defined by the peak or shoulder of the absorption caloric curve at the temperature is 7
When the temperature is in the range of 0 ° C. to 110 ° C., sufficient toner fixing performance can be obtained, and no offset occurs. On the other hand, the fluidity, heat resistance, durability and storage stability of the toner are still insufficient, and the life of the developer due to carrier spent by the toner and the life of the photoconductor due to filming of the photoconductor by the toner are likely to occur. It has been found that stable recording of an electrostatic toner image cannot be realized.

When the cause was examined in detail, it was found that the dispersibility of the polyethylene wax in the toner was not sufficient, and the fluidity, heat resistance, durability and storage stability of the toner were reduced.

As a method of improving the dispersibility of the wax in the toner, there is a method of increasing the energy during hot melt kneading of the toner and increasing the compatibility between the wax and the fixing resin. However, in this method, when sufficient energy for improving the dispersibility of the wax is applied to the fixing resin, the fixing resin is mechanically damaged, and the fixing property and the high-temperature offset resistance are reduced.

Therefore, as another method for improving the dispersibility of the wax, as disclosed in JP-A-5-313413, JP-A-9-281748, JP-A-9-304966, etc. When a coexisting polymerization method in which a wax coexists in all or a part of the synthesis process when synthesizing a resin was examined, the wax was uniformly dispersed in the fixing resin without deterioration of the resin. Further, when the fixing resin obtained from the above method is applied to the toner, the fluidity, heat resistance, durability, and storage stability of the toner are improved, the life of the developer is reduced by carrier spent by the toner, and The life of the photoconductor was hardly reduced by photoconductor filming, and a stable electrostatic toner image could be recorded and formed.

In the present invention, the polyethylene wax contains a moderately low molecular weight component to expand the molecular weight distribution. However, in order to obtain sufficient fixing property and anti-offset property, the melt viscosity of the polyethylene wax at 140 ° C. It is necessary to control the molecular weight distribution so as to be less than 10 mPa · s. If the melt viscosity of the polyethylene wax exceeds this range, sufficient fixability and offset resistance cannot be obtained by high-speed fixing using fine particle toner.

On the other hand, in order to ensure the heat resistance, durability and storage stability of the toner, the melting point of the polyethylene wax determined by DSC must be in the range of 70 ° C. to 110 ° C. If the melting point of the polyethylene wax is less than 70 ° C., the fusion property of the toner increases, the heat resistance, durability, and storage stability decrease, the life of the developer decreases due to the carrier spent by the toner, and the photoconductor filming by the toner. , The life of the photosensitive member is likely to be reduced. When the melting point of the polyethylene wax exceeds 110 ° C., the fixing property and the offset resistance of the toner are reduced.

The polyethylene wax of the present invention is a low polymer of polyethylene obtained industrially by a medium-pressure method or a low-pressure polyethylene polymerization method using a Ziegler catalyst or a metallocene catalyst, and can be obtained by purifying it. . That is, oil components, oligomers and the like are removed from a low-polymerized polyethylene by a vacuum distillation method or the like, and a distillate residue obtained therefrom is obtained by appropriately removing low-molecular-weight components under a high temperature and a high vacuum as needed. .

Specific examples of the above polyethylene wax include Neowax L (trade name, manufactured by Yasuhara Chemical Co., Ltd.)
The same AL, the same LS, the same CL, the same ACL, and the like.

In the present invention, the molecular weight distribution of the polyethylene wax is measured by GPC at a high temperature under the following conditions. GPC measurement conditions Apparatus: ALC / GPC 150-C (Waters) Separation column: GMH-HT 60 cm × 1, GMH-HT
L60cm x 1 (manufactured by Tosoh Corporation) Column temperature: 135 ° C Mobile phase: o-dichlorobenzene Detector: differential refractometer Flow rate: 1.0 ml / min Sample concentration: 0.15 wt% Injection volume: Measured under 400 μl or more conditions In calculating the molecular weight of the sample, a molecular weight correction curve prepared from a monodisperse polystyrene standard sample is used, and the molecular weight is calculated by converting to polyethylene using a conversion formula derived from the Mark-Houwink-Sakurada equation or the viscosity equation.

In the present invention, the melt viscosity is measured at 140 ° C. using a Brookfield viscometer. Also, the DSC measurement measures the heat exchange of the wax,
Since the behavior is observed, it is preferable to measure with a highly accurate internal heating type input compensation type differential scanning calorimeter from the measurement principle. For example, TA Instruments' 2910 can be used. As measurement conditions, about 5 mg of polyethylene wax was weighed and placed on a DSC, and 50 ml of nitrogen gas was blown per minute, and the temperature was raised from 20 ° C. to 150 ° C. at a rate of 10 ° C. per minute. From 150 ° C to 20
After quenching to ℃ and taking the previous history, once again
The temperature is raised at a rate of 0 ° C., and the melting point of the wax is determined from the peak or shoulder of the DSC calorific value curve at that time.

As other physical properties of the polyethylene wax, it is desirable that the penetration at 25 ° C. is as small as possible. However, since the wax having a large molecular weight distribution in the present invention contains a low molecular weight component appropriately, JIS-K
The penetration measured according to -2207 is 3 to 5.

In the toner of the present invention, the amount of polyethylene wax added is 0.5 to 20 wt.
% Is preferably added. If it is less than 0.5 wt%, the effect of improving the fixing performance of the toner is reduced, and
Exceeding the range tends to cause high-temperature offset of the toner.
Further, the wax may be used in combination with other waxes, but care should be taken not to impair the performance of the polyethylene wax of the present invention.

The vinyl copolymer used in the fixing resin of the present invention contains a styrene monomer and / or a (meth) acrylate monomer as a constitutional unit, and contains other vinyl copolymers. A monomer may be included.

Specific examples of the styrene monomer in the present invention include, in addition to styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene,
p-ethylstyrene, 2,4-dimethylstyrene, pn-
Butylstyrene, p-ter-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-dodecylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4- Dichlorostyrene and the like can be mentioned.

Specific examples of the acrylate or methacrylate 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, stearyl methacrylate, In addition to alkyl esters of acrylic acid or methacrylic acid, such as 2-chloroethyl acrylate, phenyl acrylate, α-methyl methyl acrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, dimethyl methacrylate Chill aminoethyl,
2-hydroxyethyl methacrylate, glycidyl methacrylate, bisglycidyl methacrylate, polyethylene glycol dimethacrylate, methacryloxyethyl phosphate, and the like.
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 α- or β-alkyl derivatives thereof, fumaric acid, maleic acid, Examples thereof include unsaturated dicarboxylic acids such as citraconic acid and itaconic acid and monoester derivatives and diester derivatives thereof, monoacryloyloxyethyl succinate, monomethacryloyloxyethyl succinate, acrylonitrile, methacrylonitrile, and acrylamide.

In the fixing resin of the present invention, the above-mentioned vinyl monomers are used to carry out the coexistence polymerization in which the polyethylene wax of the present invention coexists in all or some of the steps of the synthesis so that the polyethylene wax can be uniformly prepared. Can be obtained at least as a component thereof. The vinyl copolymer is mainly a monomer having two or more polymerizable double bonds, for example, divinylbenzene, divinylnaphthalene, ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, divinylaniline, Partially cross-linked with a cross-linking agent such as vinyl ether, divinyl sulfide, divinyl sulfone, or the like.

In the toner of the present invention, the charge amount of the toner can be controlled to a desired value by blending (internal addition) or mixing (external addition) the charge control agent with the toner particles.

Examples of the positive charge control agent for the toner include denatured products such as nigrosine and fatty acid metal salts; quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonic acid and tetrabutylammonium tetrafluoroborate; Onium salts such as phosphonium salts which are analogs thereof and their lake pigments, triphenylmethane dyes and these lake pigments,
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; alone or in combination of two or more thereof Can be used. Of these, charge control agents such as nigrosine, quaternary ammonium salts, and triphenylmethane dyes are particularly preferably used.

As the negative charge controlling agent for the toner, an organic metal complex and a chelate compound are effective, and examples thereof include a monoazo metal complex, an acetylacetone metal complex, an aromatic hydroxycarboxylic acid, and an aromatic dicarboxylic acid-based metal complex.
Other examples 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 0.1 to 10% by weight to the fixing resin.

In the toner of the present invention, it is preferable to add a silica fine powder externally in order to improve developability, fluidity, charge stability and durability. The silica fine powder preferably has a specific surface area of 30 m ² / g or more measured by nitrogen adsorption according to the BET method, and is 0.01 wt% to 5 wt% based on the toner.
Add externally in the range of wt%. Further, if necessary, the silica fine powder is used with a treating agent such as various organosilicon compounds or with various treating agents for hydrophobizing or controlling the chargeability.

Further, other additives to the toner include:
For example, lubricant powders such as Teflon resin powder, zinc stearate powder, and polyvinylidene fluoride powder, among which polyvinylidene fluoride is preferable. Alternatively, abrasives such as cerium oxide powder, silicon carbide powder and strontium titanate powder, among which strontium titanate is preferred. Alternatively, for example, a fluidity-imparting agent such as a titanium oxide powder and an aluminum oxide powder, particularly a hydrophobic agent is preferable. An anticoagulant, or a conductivity-imparting agent such as a carbon black powder, a zinc oxide powder, an antimony oxide powder, and a tin oxide powder, and a small amount of a white fine particle and a black fine particle of opposite polarity can be used as a developability improver.

When the toner of the present invention is used as a two-component developer, it is used by mixing with a carrier. In this case, the mixing ratio of the toner and the carrier is preferably 2 to 10% by weight 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 those obtained by treating the surfaces thereof with a fluorine-based resin, a vinyl-based resin, or a silicone-based resin are used.

The toner of the present invention is usually used as a two-component developer composed of a toner and a carrier. However, the toner further contains a magnetic material and can be used as a one-component developer as a magnetic toner. In this case, the magnetic material can also serve as a colorant. 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; and aluminum, cobalt, copper, lead, magnesium, and tin of these metals. Zinc, antimony,
Alloys with metals such as calcium, manganese, selenium, titanium, tungsten, vanadium and mixtures thereof.

The magnetic material preferably has an average particle diameter of 2 μm or less, preferably about 0.1 to 0.5 μm.
t% to 70 wt% is good.

The coloring agent that can be used in the toner of the present invention includes any suitable pigment or dye. Examples of toner colorants include pigments such as carbon black, aniline black, acetylene black, naphthol yellow, hansa yellow, rhodamine lake, alizarin lake, bengara, phthalocyanine blue, and indanthrene blue. These are used in amounts necessary and sufficient to maintain the optical density of the fixed image, and are preferably added to the resin in an amount of 0.2 wt% to 10 wt%.

Further, a dye is used for the same purpose. For example, there are azo dyes, anthraquinone dyes, xanthene dyes, and methine dyes, which are added to the resin in an amount of 0.1%.
2 wt% to 10 wt% are added.

To prepare the toner for electrostatic charge development according to the present invention, a fixing resin in which wax is uniformly dispersed, a charge controlling agent, a pigment or dye as a colorant, a magnetic powder, and if necessary, other wax or After thoroughly mixing the additives with a mixer such as a Henschel mixer or a super mixer, melt-kneading using a hot-melt kneader such as a heating roll, kneader or extruder to thoroughly mix the materials, and then cool and solidify Thereafter, fine pulverization and classification are performed to obtain a toner having an average particle diameter of 6 μm to 10 μm. Further, if necessary, a desired additive is adhered to and mixed with the toner by using 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, a latent electrostatic image formed on a photosensitive member serving as an electrostatic charge holding member is visualized using a two-component developer composed of a toner and a carrier. The image is transferred onto a recording medium, and the image forming apparatus for fixing the toner image by heating the recording medium holding the toner image shows particularly good fixing performance, and the fluidity of the toner.
Excellent heat resistance, durability, and storage stability, less likely to reduce developer life due to carrier spent by toner, and photoreceptor life due to photoreceptor filming with toner, and record stable electrostatic toner images It is possible to provide an image forming apparatus that can be used.

Hereinafter, specific examples of the present invention will be described, but the present invention is not limited thereto. (Specific 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 500,000. A mixture of 200 g of this resin and 45 g of polyethylene wax (trade name: Neowax L, manufactured by Yasuhara Chemical Co., Ltd.) was placed in a 3-liter separable flask, and xylene 1 was added.
After dissolving in liters and replacing the gas phase with nitrogen gas, the system was heated to the boiling point of xylene (135-145 ° C).

With the xylene refluxing, 440 g of styrene and 65 g of n-butyl acrylate were stirred while stirring.
Solution polymerization was carried out while dropping a mixture in which 30 g of t-butylperoxy-2-ethylhexanoate was dissolved as a polymerization initiator over a period of 2.5 hours, and the polymerization was carried out in the presence of a high molecular weight polymer and polyethylene wax. A polymer component having a molecular weight was polymerized. After completion of the dropwise addition, the mixture was aged for 1 hour while stirring at a temperature at which xylene boils. Thereafter, while gradually raising the temperature of the system to 180 ° C., xylene was desolvated under reduced pressure, and the peak of the molecular weight distribution on the low molecular weight side became approximately 8%.
One thousand resins HT-1 were obtained.

In the resin HT-1, the content of polyethylene wax is about 6 wt%, and the wax is a purified product of a low polymer of medium-low pressure polyethylene, and has a weight average molecular weight / number average molecular weight (Mw / Mn). ) Is 1.86, the melt viscosity at 140 ° C. is 8.6 mPa · s, and the DSC peak has two melting points at 74 ° C. and 94 ° C.

Next, 91 wt% of a styrene-acrylic copolymer resin HT-1 containing polyethylene wax,
Chromium-containing metal dye (trade name, manufactured by Orient Chemical Industries, Ltd.)
A toner material composed of 1 wt% of Bontron S-34) and 8 wt% of carbon black (trade name: MA-100, manufactured by Mitsubishi Chemical Corporation) is premixed by a super mixer, hot melt kneaded by a twin screw kneader, and then jet milled. And then classified by a dry air classifier to obtain particles having an average particle size of 9 μm.

Further, 0.8 wt% of hydrophobic silica (Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.) was added to the particles.
Was added and stirred with a Henschel mixer to attach hydrophobic silica to the surface of the particles to obtain the toner of the present invention. (Specific Example 2) As a polyethylene wax, a purified product of a low polymer of a medium-to-low pressure method polyethylene, weight average molecular weight / number average molecular weight (Mw / Mn) 1.71, melt viscosity at 140 ° C. 8.5 mPa · s, DSC The toner according to the present invention was obtained in the same manner as in Example 1, except that a wax having a melting point of 97 ° C. and a shoulder having a melting point of 73 ° C. (trade name: Neowax AL, manufactured by Yashara Chemical Co., Ltd.) was used. (Specific Example 3) As a polyethylene wax, a purified product of a low polymer of a medium-to-low pressure method polyethylene, weight average molecular weight / number average molecular weight (Mw / Mn) 1.78, melt viscosity at 140 ° C. 8.5 mPa · s, DSC The toner according to the present invention was obtained in the same manner as in Example 1 except that a wax having a melting point of 95 ° C. and a shoulder having a melting point of 70 ° C. (trade name: Neowax LS, manufactured by Yashara Chemical Co., Ltd.) was used. Comparative Example 1 A fixing resin HT-2 for comparison was obtained in the same manner as in Example 1 except that no polyethylene wax was added and coexistence polymerization was not performed. The maximum value of the molecular weight distribution of HT-2 is about 600,000, and the peak of the molecular weight distribution on the low molecular weight side is about 8
The molecular weight distribution almost the same as that of HT-1 was obtained at 1,000.

Next, 85% by weight of a styrene-acrylic copolymer resin HT-2 and 1% by weight of a chromium-containing metal dye (trade name: Bontron S-34, manufactured by Orient Chemical Industry Co., Ltd.)
%, The polyethylene wax used in Example 1 (trade name: Neowax L, manufactured by Yasuhara Chemical Co., Ltd.), 6 wt%, carbon black (trade name: MA-10, manufactured by Mitsubishi Chemical Corporation)
0) A toner raw material having a blending ratio of 8 wt% is preliminarily mixed with a super mixer, hot-melt kneaded with a twin-screw kneader, pulverized with a jet mill, and then classified with a dry air classifier to have an average particle diameter of 9 μm. I got Further, hydrophobic silica (manufactured by Nippon Aerosil Co., Ltd., trade name: Aerosil R97) is added to the particles.
2) 0.8 wt% was added, and the mixture was stirred with a Henschel mixer to attach hydrophobic silica to the surface of the particles to obtain a comparative toner. (Comparative Example 2) The polyethylene wax of Specific Example 2 (manufactured by Yashara Chemical Co., Ltd.) as a polyethylene wax
A comparative toner was obtained in the same manner as in Comparative Example 1 except that Neowax AL) was used. (Comparative Example 3) As the polyethylene wax, the polyethylene wax of Specific Example 3 (manufactured by Yasuhara Chemical Co., Ltd.)
A comparative toner was obtained in the same manner as in Comparative Example 1 except that Neowax LS) was used.

The toners of the above specific examples and comparative examples were evaluated for fixing performance, storage stability, fluidity, and developer life by the following methods. (1) Non-offset temperature range In an electrophotographic laser beam printer using an organic photoconductive photoconductor (OPC) as a photoconductor, the charging potential of the OPC is −650 V, the residual potential is −50 V, the developing bias potential is −400 V, and the development is performed. With a partial contrast potential of 350 V,
Print speed of 60 sheets per minute (print process speed 26.7cm
/ Sec). In the developing device, a magnetite carrier coated with a conductive agent-containing silicone resin and having a weight average particle diameter of 100 μm (electrical resistance 4.1) was used.
× 10 ⁸ Ω · cm), a developer is prepared at a toner concentration of 2.5 wt%, and the developing gap (distance between the photosensitive member surface and the developing roller surface) is set to 0.8 mm by a magnetic brush developing method. In the region, the photosensitive member and the developing roller were arranged so as to move in the same direction, and the peripheral speed ratio (developing roller / photosensitive member) of both was set to 3, and an image was produced by a reversal developing method.

The fixing device is a device in which an aluminum core is thinly covered with a tube of a fluororesin (tetrafluoroethylene-perfluoroalkylvinyl ether copolymer: PFA) (thickness: 40 μm), and a heater lamp is provided at the center. Is used as a heat roller, and a silicone rubber layer (thickness 7 mm) having a rubber hardness of about 30 degrees is installed on an aluminum cored bar.
The outermost layer covered with a PFA tube is used as a backup roller, and the fixing condition is a process speed of 26.7 cm /.
Seconds, outer diameter of heat roller and backup roller φ60mm,
The pressing load was 50 kgf, the width of the contact area (nip) between them was about 7 mm, and the control temperature of the heat roller was changed to evaluate the offset from the stain on the white paper portion of the fixed image at each surface temperature of the heat roller. The heat roller is equipped with a Nomex paper winding type cleaner originally impregnated with silicone oil. However, when evaluating the offset, remove the cleaner and use thick paper (thickness of about 200 μm) without silicone oil. ) And thin paper (thickness: about 100 μm), and the former was evaluated for low-temperature offset and the latter for high-temperature offset. (2) Fixing strength The surface temperature of the heat roller of the fixing device was set to 175 ° C., and a solid black image of 1 inch square and a line drawing of laser beam 1 on 4 off interval recorded on a thick paper (thickness about 100 μm). Then, a tape peeling test and a rubbing test were respectively performed to evaluate the fixing strength of the image.

In the tape peeling test, a scotch mending tape 810 was attached to a solid black image, and the image density before and after the tape was peeled off was measured with a reflection densitometer (RD-9 manufactured by Macbeth).
14), and the tape peeling strength was determined based on the formula of “tape peeling strength (%) = reflection density of solid black image after tape peeling / reflection density of solid black image before tape peeling × 100”.

In the rubbing test, the line drawing was rubbed with a Whatman filter paper 44 under a load of 200 gf, the degree of stain on the filter paper was evaluated with a whiteness meter, and the ratio of the light reflectance between the dirty filter paper and the clean filter paper was determined by the Hunter value. (%) And the rubbing strength (%). (3) Storage stability Put the toner in a metal petri dish and adjust the humidity to 91% with a humidity control agent.
It was left in a desiccator controlled at RH at 50 ° C. for 24 hours, and the degree of aggregation of the toner was visually evaluated. (4) Fluidity 4 g of the toner is covered with an orifice in a funnel (orifice diameter 2.63 mm, orifice length 3.2 mm, funnel cone angle 60 ° 30 ′) for measuring the fluidity of metal powder based on JIS-Z-2502. After filling, the funnel was vibrated to open the orifice and the toner was dropped, and the time required for the toner to finish falling was evaluated as the fluidity of the toner. The shorter the falling time of the toner, the better the fluidity. (5) Developer Life A nomex paper take-up type cleaning machine in which the heat roller is impregnated with silicone oil by the above laser beam printer is installed, and the surface temperature of the heat roller is set to 180 ° C.
A continuous printing test of 50,000 pages is performed, a small amount of developer is collected from the developing device, and the amount of carrier spent by toner is measured. The amount of carrier spent is measured using a carbon-in-metal analyzer (EMIA-110 manufactured by HORIBA, Ltd.) to measure the amount of carbon (%) per unit weight of the used carrier and the unused carrier from which toner has been removed, and evaluates the difference between the two. did.

Table 1 shows the evaluation results of the above items.

[0066]

[Table 1]

As can be seen from the evaluation results in Table 1, the toners of Examples 1 to 3 according to the present invention hardly cause an offset from a low temperature to a high temperature, can secure a non-offset temperature range, and have a certain temperature of the fixing device. Even if it fluctuates, the image after fixing is hardly stained. The fixing strength at a fixing temperature of 175 ° C. is 70% or more for both the tape peeling strength and the rubbing strength.
Practical fixing strength was obtained. Further, the fluidity of the toner is good, the carrier spent is small, and the storage stability is good. On the other hand, the toners of Comparative Examples 1 to 3 have a wide non-offset temperature range and a sufficient fixing strength, but have poor fluidity of the toner and a large amount of carrier spent. It was found that the life was poor and it was difficult to put to practical use.

When each of the toners of Examples 1 to 3 was applied to the above laser beam printer, and continuous printing was performed, even if continuous printing of 300,000 pages was repeated, a decrease in the life of the developer due to carrier spent caused by the toner, and As a result, the life of the photosensitive member was not shortened by the filming of the photosensitive member, and a stable image could be obtained.

The configuration of the laser beam printer will be described with reference to FIG.

Reference numeral 1 denotes a basic device main body. The basic device main body 1 includes a printing unit 3 that can be pulled out from the device frame 2. Reference numeral 4 denotes a photosensitive drum on which a toner image is recorded and formed by a well-known electrophotographic process, and is supported by a spindle so as to rotate at a constant speed in the direction of arrow a.

The charger 5 is arranged so as to face the surface of the photosensitive drum 4, and uniformly charges the surface of the photosensitive drum 4 passing so as to face the charger 5. Laser light 6 for exposing the uniformly charged surface of photoreceptor drum 4
Forms an electrostatic latent image on the surface of the photosensitive drum 4 according to a print information signal supplied from the information processing apparatus.

The developing device 7 is arranged so as to face the surface of the photosensitive drum 4 on which the electrostatic latent image has been formed. The developing device 7 has a developing function of forming the toner image by causing the toner described above to adhere to the surface of the photosensitive drum 4 with the electrostatic force of the electrostatic latent image.

The cassette 8 stores a stack of sheet-like recording media (paper) 9 for transferring and fixing the toner image and printing an image. A paper feed roller mechanism 10 constituting a part of the recording material conveying means takes in the paper 9 from the cassette 8 and sends it out to the photosensitive drum 4.

The paper 9 sent out from the paper feed roller mechanism 10 comes into contact with the surface of the photosensitive drum 4 so as to transfer a toner image onto the surface. The transfer unit 11 applies a charge having a polarity opposite to that of the toner image to the back surface of the sheet 9 in contact with the surface of the photosensitive drum 4 to transfer the toner image formed on the surface of the photosensitive drum 4 to the sheet 9. Generate electrostatic force.

The transport belt 12 which forms another part of the paper transport means transports the paper 9 on which the toner image has been transferred to the fixing device 1.
Send to 3. A pair of fixing rollers 14 each including a heat roller 14a and a backup roller 14b pressed against each other;
Heats and presses the sheet 9 to fix the toner image on the surface of the sheet 9.

The paper 9 sent from the fixing device 13 is
In accordance with the position of the sheet transport path switching member 15, the discharge unit 1
6 or the paper 9 sent out from the fixing device 13 to the discharge unit 17 halfway.
To the paper path 20 for duplex printing at a predetermined timing.
The paper 9 is conveyed to the side, and the printing paper on which the front side printing is completed is supplied again to the printing unit 3 so that the back side of the paper is printed.

In FIG. 1, reference numeral 18 denotes the transfer device 1.
A cleaning device 19 for removing foreign matters such as toner and paper dust remaining on the surface of the photoconductor drum 4 after one passage from the surface of the photoconductor drum 4, and a reference numeral 19 for replenishing the developing device 7 with toner as necessary This is a toner supply device. In FIG. 1, a laser beam printer equipped with a developing device having one developing roller is illustrated, but a developing device having two or more developing rollers may be used. A laser beam printer equipped with a center feed type developing device including a developing roller rotating in the same direction as the photosensitive drum and a developing roller rotating in the opposite direction to the photosensitive drum may be used.

[0078]

As described above, according to the present invention, a toner which is excellent in fluidity, heat resistance, durability and storage stability and which can reduce the energy required for fixing, and using the same. An image forming apparatus can be provided.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a laser beam printer to which the present invention is applied.

[Explanation of symbols]

4 photoreceptor drum, 5 charger, 6 laser light, 7 developing device, 11 transfer device, 13 fixing device, 18 cleaning device.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Katsuya Kawai 1060 Takeda, Hitachinaka City, Ibaraki Prefecture Inside Hitachi Koki Co., Ltd. (72) Inventor Nobuyoshi Hoshi 1060 Takeda Hitachinaka City, Ibaraki Prefecture Inside Hitachi Koki Co., Ltd. (72) Inventor Akira Hosoya 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture F-term in Hitachi Research Laboratory, Hitachi Ltd. F-term (reference) 2H005 AA01 AA06 AB02 AB06 CA04 CA13 CA14 EA03 EA06 EA10 FB02

Claims (6)

[Claims] 1. An electrostatic charge developing toner containing a fixing resin and a wax, wherein the fixing resin comprises a vinyl copolymer polymerized in the presence of a polyethylene wax obtained by purifying a low-molecular-weight low-molecular-weight polyethylene. A toner for electrostatic charge development, characterized by containing. 2. The wax according to claim 1, wherein a value of weight average molecular weight / number average molecular weight (Mw / Mn value) is larger than 1.5.
The toner according to claim 1, wherein the melt viscosity at 40 ° C. is less than 10 mPa · s. 3. The wax has a melting point of 70 ° C. or more defined by a peak or a shoulder of an absorption calorie curve at the time of temperature rise in a DSC curve measured by a differential scanning calorimeter.
3. The toner according to claim 1, wherein the temperature is in the range of 110.degree. 4. A static resin comprising a fixing resin and a colorant as main components, wherein the fixing resin contains a vinyl copolymer which is polymerized in the presence of a polyethylene wax obtained by purifying a low polymer of a medium-to-low pressure process polyethylene. Developing means for supplying the toner for charge development to an electrostatic charge holding member holding the electrostatic latent image, and developing the electrostatic latent image as a toner image; and a toner image formed on the electrostatic charge holding member. An image forming apparatus comprising: a transfer unit that transfers the toner image onto a recording medium; and a fixing unit that applies at least heat to the recording medium holding the toner image and fixes the toner image on the recording medium. 5. The wax has a weight average molecular weight / number average molecular weight value (Mw / Mn value) of more than 1.5 and not more than 1.5.
The image forming apparatus according to claim 4, wherein the melt viscosity at 40 ° C is less than 10 mPa · s. 6. The wax has a melting point of 70 ° C. or more defined by a peak or a shoulder of an absorption calorie curve at the time of temperature rise in a DSC curve measured by a differential scanning calorimeter.
The image forming apparatus according to claim 4, wherein the temperature is in a range of 110 ° C. 7.