JPS61248059A - Toner - Google Patents

Abstract

PURPOSE:To prevent pulverous particles to be incorporated into a tone from staining the surface of a photosnsitive body and the surface of a toner carrying body by subjecting preliminarily the pulverous particles to a treatment using a specific material. CONSTITUTION:This toner consists of a resin binder and the pulverous particles. The pulverous particles are preliminarily treated with a low mol.wt. polyolefin compd. of which the melt viscosity and 120 deg.C is 5<=eta<=5X10<3> centipoise. The low mol.wt. polyolefin compd. to be used is preferably ethylene, etc. having about 500-15,000 number average mol.wt. The melt viscosity eta below 5 centipose or above 5X10<3> centipoise is undesirable as in both cases the defective dispersibility arises. The pulverous particles of which the BET specific surface area is preferably 1.0-100m<2>/g is preferred. above all, a good result is obtd. when an org. pigment having 10-100m<2>/g BET specific surface area, more particularly phthalocyanine pigment and azo pigment are used.

Description

Detailed Description of the Invention [Technical Field to which the Invention Pertains] The present invention relates to a method for developing an electrostatic latent image or a magnetic latent image formed by electrophotography, electrostatic recording, electrostatic printing, or magnetic printing. Regarding the toner used for

[Description of prior art]

In image forming methods conventionally known as electrophotography, electrostatic printing, electrostatic recording, and magnetic printing, images are formed.

It involves the process of visualizing the image using a colored fine powder called toner. For example, as an electrophotographic method, US Pat.
Various methods are known, as described in Japanese Patent Publication No. 43-24748, but in general, electrostatic images are formed on the surface of a photoreceptor using a photoconductive substance by various methods. 1. Next, the electrostatic charge image is developed with toner, and if necessary, the toner image is transferred to a transfer material such as paper, and then fixed by heating, pressure, etc. to obtain a copy. .

Electrostatic printing is a method of printing by using an electric field to guide and fix charged powder toner onto a recording material.

Electrostatic recording is a method in which a charge is applied to an image on a dielectric layer, and charged toner powder is attached to and fixed on the image.
Similarly, the magnetic printing method is a method in which a magnetic latent image is formed on a recording material, developed with toner powder containing a magnetic material, and transferred and fixed onto a transfer material.

Various developing methods are known to visualize such electrical or magnetic latent images using toners, but the toners used in these developing methods have conventionally been binder resins made of natural or synthetic resins. Fine powder in which fine particles of coloring agents such as dyes and pigments are dispersed is used. for example,
41J styrene is used as the binder resin, and particles in which a colorant is dispersed and pulverized to about 1 to 30 μm are used as the toner. Further, when obtaining a magnetic toner, one containing magnetic particles such as magnetite is used.

There are two-component developers that use the toner mixed with carrier particles such as glass peas and iron powder, and one-component developers that use only toner without using carrier particles.

These toners are required to have various physical and chemical properties such as triboelectricity, fluidity, and impact resistance. However, few conventional toners satisfy all of these characteristics, and many of the known toners have several problems as described below. That is, the triboelectric properties of many toners are adversely affected by changes in environmental humidity. In addition, with many toners, the density of the resulting image decreases due to mutual deterioration of the toner, carrier particles, and photosensitive plate due to collisions between toner particles and carrier particles due to repeated development due to continuous use, and contact between these particles and the surface of the photosensitive plate. or the background density increases, reducing the quality of the copy. Furthermore, with many toners, if an attempt is made to increase the density of a copied image by increasing the amount of toner adhering to the surface of a photosensitive plate having a latent image, the background density usually increases, resulting in a so-called fog phenomenon.

Since many known toners have one or more of the above defects, there is a continuing need for improvements in toners.

In addition, recently, there has been a demand for a compact and inexpensive color copying machine that can produce images in desired colors as needed, as the purposes for which the above-mentioned electrophotography is used is diverse. There is an urgent need to develop In this sense, color toners need not only to have excellent physical and chemical properties that overcome the above-mentioned defects, but also to have good hue.

Further, in addition to the binder resin and the colorant, auxiliary agents such as a charge control agent may be added to the toner as necessary.

However, conventional dyes and pigments, substances known as charge control agents, when used as toner materials, have a single hue, charge control properties, environmental dependence, and heat resistance.

None of them satisfied all the properties such as light resistance and fixing properties, and they had some problems.

For example, when a dye is used as a coloring agent, it is easy to obtain a clear hue, but it has the following problems. It generally has poor heat resistance and light resistance, and has a strong tendency to discolor or fade due to damage caused by heat kneading during toner manufacturing, or when the resulting image is exposed to artificial light or left outdoors for long periods of time. . Alternatively, when the developer is stored at a relatively high temperature, the toner tends to aggregate.

For example, when pigments are used as colorants, they are generally superior to dyes in terms of heat resistance and light resistance, and toner aggregation does not tend to occur even when stored at high temperatures. be. However, many pigments have problems in dispersibility in binder resins. In other words, this is not a major problem when using a binder resin made of a polymer with a relatively low molecular weight, but pigment dispersion may be difficult when using a binder resin with a relatively high molecular weight or a crosslinked type. The problem arises of wanting to be done well.

For example, phthalocyanine pigments, which are used in an extremely wide range of fields as blue to green pigments, are a typical example of the pigments that tend to cause poor dispersion as described above when used in electrophotographic toners. As a result, the following characteristic problems arise. That is, many pigments have poor coloring power to toner, and therefore it is necessary to add a large amount of pigment, which deteriorates fixing properties. In addition, due to variations in the distribution of pigment within toner particles (some toner particles containing a large number of pigment particles and some toner particles containing no pigment particles at all), the chargeability of the toner itself may be affected. Unstable use over a long period of time or environmental changes (temperature/humidity fluctuations) may cause problems such as a decrease in image density and an increase in soil blur. Furthermore, since there are naked pigment particles that are not incorporated into the toner particles, they contaminate the surface of the photoreceptor or toner carriers such as sleeves and carriers, resulting in filming, image deletion, and
For example, it may cause undesirable phenomena such as poor cleaning, soil blurring, and a decrease in image density.

As described above, the current situation is that even if dyes or pigments are directly incorporated into toners as colorants, only toners with certain problems can be obtained.

[Purpose of the invention]

The present invention has been made in view of the above points.

That is, the main object of the present invention is to provide a toner having excellent electrophotographic properties in which fine particles do not cause contamination on the surface of a photoreceptor or toner carrier.

Another object of the present invention is to develop a latent image faithfully.

To provide a toner that performs transfer and fixation, that is, a toner that does not cause fogging, toner scattering in the peripheral area of a latent image, poor fixing, offset, etc., has high single image density, and has excellent reproducibility in the 8-tone area. .

Another object of the present invention is to provide a toner that maintains its initial good characteristics even after long-term use and environmental changes.

Yet another object of the present invention is to triboelectrically charge the toner between toner particles, between a toner and a carrier, or on a toner carrier in the case of 1≦min development by any frictional means. It is an object of the present invention to provide a developer which is stable, has a uniform triboelectric charge amount distribution, and can be controlled to a charge amount suitable for the developing system used. However, all the frictional means mentioned here include frictional charging of the toner by a toner carrier spool developing sleeve, or frictional charging by other frictional members.

[Structure of the invention]

As a result of extensive research, the inventors of the present invention have discovered that the above-mentioned object can be achieved by treating the fine particles contained in the toner with a specific substance in advance.

That is, the toner of the present invention comprises at least a binder resin and fine particles, and the fine particles are pre-treated with a low molecular weight +617 year old reflex compound having a melt viscosity (η) of 5≦η≦5×103 centipoise at 120°C. It is characterized by being processed.

The low molecular weight IJ olefin compounds used in the present invention include ethylene with a number average molecular weight of about 500 to 1 sooo;
Ethylenically unsaturated monoolefin polymers such as propylene, butylene, and inbutylene; and with these, vinyl acetate, styrene, methyl acrylate, ethyl acrylate, methyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate,
Copolymers with vinyl threads such as vinyl chloride, copolymers with polymeric compounds such as polyamide, polyester, polyurethane, polyepoxy, polyurea, etc. are preferred. In the present invention, polyethylene, polypropylene, or a styrene-acrylic copolymer thereof is particularly preferred.

Further, the low molecular weight polyolefin compound used in the present invention is characterized in that the melt viscosity η at 120° C. is 5≦≦5×10′ centipoise, but the above-mentioned η is less than 5 centipoise. , or 5×10 3 centipoise or more, these are both undesirable because they cause dispersion and poor quality.

Note that the melt viscosity value of the low molecular weight polyolefin compound in the present invention is measured using a Brookfield viscometer.

As the fine particles used in the present invention, all fine particles conventionally used as toner constituents can be used, and examples of these include conventionally known fine particles such as anthraquinone type, quinacridone type, phthalocyanine type, perylene type, and perinone type. Various organic pigments, such as azo-based pigments, azo threads, various inorganic pigments, such as titanium oxide, iron oxide, yellow lead group 1, and navy blue, and metal compounds, such as various metal oxides, metal chlorides, or mixtures thereof, and metal complexes, etc. I can give it to you. The fine particles have a BET specific surface area of 0.1 m2/r to 300 m2/r, preferably t
It is desirable that Q m2/r to 100 m2/f. Among them, good results can be obtained when organic pigments having a BET specific surface area of 10 to 100 m27t, particularly phthalocyanine pigments and azo pigments, are used.

A specific method for producing the fine particles used in the present invention includes, for example, dissolving a low molecular weight polyolefin compound in a solvent such as xylene, decalin, tetralin, etc., adding fine particles thereto, and then adding a nonsolvent to precipitate the low molecular weight polyolefin compound. or heat-melted low molecular weight IJ
Examples include a method in which fine particles are added to an olefin compound, cooled, and then crushed. The content of the low molecular weight polyolefin compound in the fine particles treated in this way is 0.01 to 80% by weight, preferably 0.05% by weight, based on the total amount of the fine particles.
~50% by weight, particularly preferably 0.1~30% by weight.

Further, the amount of the fine particles added in the toner of the present invention varies depending on the properties and purpose of each fine particle, but as fine particles after treatment, the toner contains 0.2 to 80% by weight, preferably 0.5 to 70% by weight, Particularly preferably 1 to 50% by weight
shall be.

The toner used in the present invention can be produced by any of the commonly used methods. Specifically, fine particles treated with a binder resin and the above-mentioned low molecular weight +Q IJ olefin compound are melted. Method of cross-crossing, cooling, crushing and classification, ■Melting cross-wire,
Dispersion in a liquid, granulation method, method of melt-kneading, spraying into a gas, granulation method, or polymerization and granulation of the fine particles pre-dispersed in a monomer constituting the binder resin. methods, etc.

Binder resins used in the present invention include monopolymers of styrene and its substituted products such as polyp-chlorostyrene and polyvinyltoluene; styrene-p-chlorostyrene copolymers, styrene-prohylene copolymers, and styrene-p-chlorostyrene copolymers. Vinyltoluene copolymer, styrene-vinylnaphthalene copolymer.

Styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-methyl chloromethacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinylethyl ether copolymer, Styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isopropylene 2 copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid copolymer, styrene-maleic acid ester Styrenic copolymers such as copolymers; polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyurethane, polyamide, epoxy resin, polyvinyl butyral, #? Reacrylic acid resin, rosin, modified rosin, chill resin, phenolic resin IJ! Aliphatic or alicyclic hydrocarbon resins, aromatic petroleum resins, chlorinated paraffins, paraffin waxes, etc. can be used alone or in combination.

The effect of the present invention is that the melt flora index value is 0.
．． 1-2C1/10 minutes (test conditions: load 10Kg, 12
A favorable effect was shown when using a binder resin at a temperature of about 5°C. The melt flora index here is based on the flow test method for thermoplastic plastics of the Japanese Industrial Standards JIS K.
The measurement was carried out using the device described in No. 7210 using the one-manual cutting method.

Furthermore, the binder resin for which the present invention is particularly effective is a vinyl polymer synthesized from a vinyl monomer having a ratio Mw,/Mn of weight average molecular weight (M, ) to number average molecular weight (Mn) of 4 or more, particularly 10 or more. It is a combination of polyester and epoxy resin.

Here, the above Mw/Mn value was calculated from the value measured by gel permeation chromatography. The measurement conditions are as follows: Tetrahydrofuran is flowed as a solvent at a flow rate of 1 g/min at a temperature of 25° C., and 0.5 g/min of a sample solution of tetrahydrofuran with a sample concentration of 81 g/min is injected.

In addition, as a column, in order to accurately measure the molecular weight range of 103 to 2X106, it is recommended to combine multiple commercially available 41J styrene gel columns.
μm Styragel 500.10' manufactured by Er Nipponsha
, 104.105 combination and 5hod manufactured by Showa Denko
The combination of ex A-802°803.804 and 805 is good. When measuring the molecular weight of a sample, check the molecular weight distribution of the sample.

It was calculated from the relationship between the logarithm value of a calibration curve prepared using several types of monodisperse 4V styrene standard samples and the count number. As a standard polystyrene sample for creating a calibration curve, for example, P
Ressure Chemical Co.

or manufactured by Toyo Tsudani Gyo Co., Ltd. with a molecular weight of 6X102゜2
, lX10', 4×103, t75X104.5, l
X104. tI×103.3.9×103.8.6×
It is appropriate to use 103.2 x 106.4.48 x 106 standard Ho IJ styrene samples of at least 10 points. In addition, the detector has an R (refractive index)
Use a detector.

Furthermore, in order to use the toner as a magnetic toner, magnetic powder may be included. As such magnetic powder, a substance that is magnetized when placed in a magnetic field is used, such as powder of ferromagnetic metal such as iron, cobalt, nickel, or agenetite.

There are various alloys and compounds such as γ-acid iron oxide rougherite. The content of this magnetic powder is preferably 10 to 70% by weight based on the weight of the toner.

The above toner composition is used as a microcapsule toner.
It is also possible to carry it on the wall material, the core material, or both.

The toner of the present invention may be mixed with carrier particles such as iron powder, glass beads, nickel powder, ferrite powder, etc., if necessary, and used as a developer for electrical latent images. The developer of the present invention can be applied to various developing methods. For example, magnetic brush development method, cascade development method, U.S. Pat.
A method using a conductive magnetic toner described in No. 909.258, a method using a high resistance magnetic toner described in JP-A-53-31136, and JP-A-54-42.
Publication No. 141, No. 55-18656, Publication No. 54-
Examples include the method described in Japanese Patent No. 43027, a fur brush development method, a powder cloud method, an impression development method, and the like.

Further, when the developer is held in a developer carrier such as a sleeve, it is possible to use magnetic force, Coulomb force, electrostatic force, image force, mechanical force, etc. Further, as the transfer method used in the present invention, conventionally known methods such as an electrostatic transfer method, a bias roll method, a pressure transfer method, and a magnetic transfer method are used. Further, as a method for cleaning the remaining toner on the photoreceptor, conventionally well-known blade cleaning methods, fur brush cleaning methods, magnetic brush cleaning methods, etc. are used, but the blade cleaning method is particularly suitable for the toner of the invention. There is. Further, immediately before the cleaning process, a static elimination process or the like may be provided as necessary to facilitate toner cleaning. The cleaning properties of the present invention were particularly favorable for OPC photoconductors (organic photoconductors) and amorphous silicon photoconductors.

〔Example〕

Hereinafter, the present invention will be explained in detail using Examples, but the present invention is not limited to these Examples in any way. Note that all parts in the examples are parts by weight.

Example 1 A copper-phthalocyanine pigment (CI Pigment blue 15) was added to a solution of 5 parts of polyethylene (η=5 cps at 120°C) dissolved in 100 parts of xylene at 60°C.
After adding 30 parts and stirring for 10 minutes, the mixture was cooled to room temperature and filtered and dried to obtain a copper-7 talocyanine pigment containing approximately 0.2 weight percent of polyethylene.

The mixture of the above formulation was heated and kneaded in a roll mill at 170° C. for 50 minutes, cooled, coarsely crushed in a hammer mill, and then finely pulverized in an air jet type pulverizer. Further, air classification was performed to select 5 to 25μ, and 1% by weight of colloidal force was added to prepare a toner. When the obtained toner was observed under a microscope, it was found that the toner particles uniformly contained pigment, and no transparent toner particles containing no pigment or pigment aggregates were observed.

Next, when the toner was used to make copies using a PC-20 copier (Canon's PC-20 is a copier that uses an OPC photoreceptor and employs a blade cleaning method), a clear blue image with no fog was obtained. was gotten. The maximum image density (hereinafter abbreviated as Dmax) at this time was t41. Furthermore, even after making 3,000 copies in a row, there was still poor cleaning.
No filming image deletion occurred and Dmax was 122.

[Comparative Example] A toner obtained in the same manner as in Example 1 except that only one of the copper-phthalocyanine pigments used in Example 1 was used without being treated was observed under a microscope.

Pigment dispersion in the toner particles was extremely poor, with transparent toner particles containing no pigment and toner particles containing pigment coexisting. Furthermore, when copying was carried out in the same manner as in Example 1, only an image with slight fogging was obtained, and moreover, DmaX was 10
It was as low as 4. Furthermore, after 3,000 continuous copies were made, the fog further increased, Dmax decreased to 0.66, and a filming phenomenon was observed on the surface of the photoreceptor.

Leek mN, + 2 polypropylene (η = 3 socps at 120°C)
Pigment b
After adding 20 parts of 1ue149) and stirring for 5 minutes, the mixture was cooled to room temperature, 350 parts of methylcarpitol was gradually added, and the mixture was further filtered and dried to obtain a perylene pigment containing 2.2 weight percent of polypropylene.

When copying was carried out in the same manner as in Example 1 using a toner obtained in the same manner as in Example 1 except that the mixture of the above formulation was used, a clear red image without fogging was obtained. Dmax at this time is 1
It was 37.

30 parts of black iron oxide was added to a solution of 2 parts of fJ-free polypropylene (η = 950 at 120°C) dissolved in 100 parts of xylene at 90°C, stirred for 60 minutes, cooled to room temperature, filtered and dried. An r-Fe205 containing 4.9 weight percent polypropylene was obtained.

A toner was obtained in the same manner as in Example 1 except that the mixture of the above formulation was used.

NP-500R1 using this toner! Using an experimental copying machine (manufactured by Canon) modified to use an amorphous silicon photoreceptor, dark area-t-soov was recorded as an electrostatic latent image.

Bright i+100V, photoreceptor surface and developing sleeve 300μ
m, and the frequency is 1800H2 and the peak-to-peak value is 1.4KV between this developing sleeve and the surface of the photoreceptor.

Development-transfer-blade cleaning was performed for 200,000 consecutive sheets by applying a voltage of +250 V to the center value and setting the transfer voltage to +8 KV, but no filming or cleaning failure occurred.

10 parts of 1m±-polyethylene (liquidity = 4800 at 120°C) were heated and melted, and red pigment (C, engineering pigment) was melted by heating.
After adding 10 parts of Red 170) and sufficiently kneading, the mixture was cooled and further crushed into powder using a speed mill.

A toner was obtained in the same manner as in Example 1 except that the mixture of the above formulation was used.

Using this toner, we used a NP-150z copier (manufactured by Canon, the NP-150Z uses an OPC photoreceptor and a blade print I).
This is a copying machine that uses the J = ng method. ), 20,000 copies were made continuously, but no cleaning defects, filming, or image deletion occurred.

Example 5 Good results were obtained when the procedure was carried out in substantially the same manner as in Example 1, except that an azo yellow pigment of C0 grade and Pigment Yellow 83 was used instead of C0 grade and Pigment blue 15.

Example 6 Good results were obtained when the procedure was carried out in almost the same manner as in Example 2, except that an azo thread red pigment of Pigment Hed38, C0 process, was used in place of C6 process, Plgment Red 149. .

[Summary of the Effects of the Invention] The toner of the present invention has fine particles mainly composed of a coloring agent of 12
Since the particles are treated with a low molecular weight polyolefin compound whose melt viscosity at 0°C is 5≦da≦5×103 centipoise, the low molecular weight contained in the particles is 4+).
The affinity and compatibility between the olefin compound and the polymer as a binder resin is improved, the fine particles are uniformly dispersed in the toner particles, and the distribution of fine particles among the toner particles is uniform. is incorporated into the toner particles with good dispersibility, and has a structural feature that there are no bare colorant fine particles. For these reasons, the toner has high coloring power, requires only a small amount of colorant added, has stable triboelectric charging properties, and has a uniform distribution of triboelectric charge, making it suitable for the developing system used. The amount of charge can be controlled to an appropriate level, image density does not decrease even after long-term repeated use or environmental changes, and there are no adverse effects such as an increase in soil blur. In addition, it does not contaminate the photoreceptor surface or toner carriers such as developing sleeves and carriers, and reduces toner scattering, poor fixing, filming, offset, image deletion, poor cleaning, and pre-image density around the latent image. Development, transfer, and fixing can be performed faithfully to the latent image without causing adverse phenomena such as deterioration.

Claims (1)

[Claims] (1) Consisting of at least a binder resin and fine particles, the fine particles have a melt viscosity (η) at 120°C of 5≦η≦
A toner characterized in that it is treated with a low molecular weight polyolefin compound having a molecular weight of 5 x 10^3 centipoise.