JPH0387840A - Developer - Google Patents

Abstract

PURPOSE:To obtain the negative chargeable developer having initial characteristics without deteriorating even after long-term preservation by specifying the content of the decomposed matter of an initiator in the polymer of the first half period polymer to <=2,500ppm of the first half period binder resin of a toner. CONSTITUTION:Polymn. reaction is effected by using a peroxide soluble in a monomer, such as benzoyl peroxide, as a polymn. initiator in many cases in production of the polymer. The resulted polymer inevitably contain much of the decomposed matter of the initiator, such as benzoic acid, and this decomposed matter of the initiator hinders the triboelectrostatic charge of the developer. This phenomenon appears particularly significantly after the long-term preservation. The effect is improved as the content of the decomposed matter of the initiator in the binder is decreased to <=2,500ppm. The good triboelectrostatic chargeability and the long-term preservable property are thus maintained and the excellent gradation characteristic, definition and durability are obtd. The removal of the decomposed matter of the initiator from the binder resin contained in the developer is executed simply by filtering the first-half period fine particulate resin out of the liquid in the stage when the suspension polymn. ends and sufficiently rinsing the resin with water after the treatment with an aq. alkaline soln. then drying the same.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a developer for developing electrostatic images in image forming methods such as electrophotography, electrostatic recording, and electrostatic printing.

More specifically, in a direct or indirect electrophotographic development method, the negative charge is uniformly negatively charged, and a positive electrostatic charge image is visualized, or a negative electrostatic charge image is visualized by reversal development, thereby producing a high quality image. This invention relates to a developer.

[Background technology]

Conventionally, as an electrophotographic method, U.S. Patent No. 2,297,69
Although many methods are known, such as those described in Japanese Patent Publication No. 1, Japanese Patent Publication No. 42-23910, Japanese Patent Publication No. 43-24748, etc., in general, photoconductive substances are used and various means are used. An electrical latent image is formed on the photoreceptor by a method, and then the latent image is developed using toner, and if necessary, the toner image is transferred to a transfer material such as paper, and then heated, pressured, heated and pressed, or The toner is fixed by solvent vapor or the like to obtain a copy, and the toner remaining on the photoreceptor without being transferred is cleaned by various methods, and the above-mentioned steps are repeated.

In recent years, such copying devices have begun to be used not only as office copy machines for copying original manuscripts, but also as printers for computer output or as personal copiers for individuals. There are also a wide variety of

Therefore, smaller size, lighter weight, higher speed, and higher reliability are being strictly pursued, and machines are being constructed from simpler elements in various respects. As a result, the performance required of the toner of a one-part developer that can simplify and downsize the developing device configuration has become more advanced, and if it is not possible to improve the performance of the toner of the developer, the performance will be even higher. The machines that used to be used are becoming obsolete.

However, -component type developers generally have little chance of being charged due to friction, and since the toner particles of the developer contain magnetic powder, their charge retention is weak. This has resulted in various problems such as insufficient image density, fogging on white backgrounds, and unsatisfactory high-humidity characteristics.

Furthermore, if such a developer is left undisturbed for a long period of time, the developer deteriorates over time, and the problems caused by the chargeability become even more pronounced.

The problem of developer storage stability or deterioration over time is especially important when using a cartridge system that integrates a photoreceptor, developer, cleaning device, etc. from a maintenance-free perspective suitable for personal use, and how and how it is used. This is expected to become an even more important issue in the future.

On the other hand, many patents and other technical documents have conventionally described the addition of a charge control agent in order to obtain stable triboelectrification of a developer. However, while the addition of a charge control agent contributes to the charge stability of the developer,
Little consideration has been given to the storage stability of the developer when it is left for a long period of time and its deterioration over time.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned drawbacks, and it is an object of the present invention to provide a negatively chargeable developer that can maintain its initial characteristics without deteriorating even after long-term storage.

Still another object is to provide a negatively charging developer in which the triboelectric charge between developer particles and between the developer and a developer carrier such as a sleeve is stable, and the triboelectric charge distribution is sharp and uniform. It is in.

Still another object is to provide a negatively charged developer that reproduces stable images that are not affected by changes in temperature and humidity.

Still another object is to provide a negatively chargeable developer that can maintain its initial characteristics even when the developer is used continuously for a long period of time.

Still another object is to provide a negatively chargeable developer that has excellent fixing properties and offset properties, and has excellent anti-blocking properties.

[Summary of the invention]

As a result of extensive studies, the present inventors have found that in a developer containing a polymer synthesized using a polymerization initiator, the polymer is washed with a basic aqueous solution or It is obtained by a process of removing initiator decomposition products such as washing with a low boiling point organic solvent, and the content of initiator decomposition products in the first polymer is 2500 ppm or less based on the first binder resin of the toner. It has been found that this can be achieved by a negatively chargeable developer characterized by the following.

Until now, as a technique for improving impurities in the binder resin of a developer, for example, Japanese Patent Publication No. 63-60906 discloses that after emulsion polymerization of the binder resin, emulsion stabilizers and coagulants in the binder resin are removed using a basic aqueous solution. A developer using the removed polymer has been proposed. According to this method, the triboelectric charging characteristics and durability of the developer tend to be improved by reducing the content of impurities such as emulsifiers, but in the emulsion polymerization method, there are problems specific to the polymerization.
Emulsifiers and coagulants are not completely removed, and the long-term storage stability of the developer is not sufficient. Furthermore, in the emulsion polymerization method, there is a demand for improved offset resistance and fixing properties.
In particular, in order to improve offset resistance, it is necessary to increase the molecular weight of the binder resin or to contain a crosslinking component by adding a crosslinking agent. However, this direction promotes the incorporation of emulsifier impurities into the binder resin and makes it difficult to remove them, so it is difficult for the binder resin to improve offset resistance and maintain predetermined performance.

Furthermore, regarding the improvement of impurities in the binder resin of a developer, a two-component developer containing a styrene-acrylic copolymer that does not contain benzoic acid units is proposed in JP-A-63-169658. .

The proposal states that good triboelectric charging properties can be achieved by reducing the reverse polarity component in the binder used in positively chargeable developers and combining it with a fluororesin-coated carrier. No consideration was given to improving storage stability.

According to the findings of the present inventors, in the production of polymers,
Polymerization reactions are often carried out using monomer-soluble peroxides such as benzoyl peroxide (BPO) as a polymerization initiator, and the resulting polymer inevitably contains decomposed products of the initiator such as benzoic acid. It has been found that the initiator decomposition product inhibits the triboelectric charging properties of the developer. This tendency is particularly noticeable when the developer is stored for a long period of time. This phenomenon is presumed to be caused by the interaction between the charge control agent and the decomposed product of the initiator, but this interaction is considered to be a type of complex formation, which destabilizes the charging property in the developer. It is undesirable for the condition to exist.

In the developer of the present invention, the content of initiator decomposition products in the binder resin is 2,500 ppm or less, more preferably 2,000 ppm or less.
p1) m or less, more preferably 1500 ppm or less, and if the content of the decomposed product is further reduced,
The effect is improved, good triboelectric charging properties and long-term storage properties are maintained, and excellent gradation, resolution, and durability are achieved.

As a method for synthesizing the binder resin contained in the developer according to the present invention, a suspension polymerization method is preferable to an emulsion polymerization method in which complete removal of emulsifiers and coagulants is difficult.

Further, as a method for removing the initiator decomposition product from the binder resin contained in the developer according to the present invention, the following can be mentioned.

(1) A method in which the fine particulate resin is filtered out from the suspension containing the particulate resin at the stage where the suspension polymerization step is completed, washed with an alkaline aqueous solution, thoroughly washed with water, and dried.

(2) Add an alkaline aqueous solution to the suspension containing the particulate resin at the stage where the suspension polymerization step has been completed, wash it, and after filtering out the particulate resin, wash thoroughly with water,
How to dry.

(3) After the fine particulate resin is filtered from the suspension containing the particulate resin at the stage where the suspension polymerization process is completed, and washed with a low boiling point organic solvent such as methyl alcohol,
How to dry.

In the binder resin of the developer according to the present invention, examples of polymerization initiator decomposition products which become impurities whose content should be limited as described above include low molecular weight compounds having a Lewis acid functional group.

The Lewis acid functional group refers to a group that attracts electron pairs, and specifically includes electron-withdrawing groups such as a carboxyl group and a carbonyl group. Benzoyl peroxide (BPO) is a low-molecular compound with this type of Lewis acid functional group.
It is often an organic acid such as benzoic acid, which is a decomposition product of As the proton-donating ability of the initiator increases, the proportion of initiator decomposition products generated increases. Therefore, unlike suspension polymerization, monomers are strongly dispersed in water, and the initiator decomposition products have low solubility in the dispersion medium. When indicating,
In particular, the binder resin cleaning treatment as described above is very effective.

On the other hand, in order for the binder resin to have sufficient fixing properties, anti-offset properties, and further anti-blocking properties, it is necessary to adjust the THF-insoluble content of the binder resin, that is, the proportion of crosslinked components in the binder resin, and the molecular weight of the THF-soluble content. This can be achieved with certain configurations of the distribution.

Basically, THF-insoluble components mainly affect offset resistance, and THF-soluble components with a molecular weight of 10,000 or less mainly affect blocking properties, fusion properties to the photoreceptor surface, and THF The soluble components having a molecular weight of 10,000 or more mainly affect the fixing properties. The proportion of components having a molecular weight of 10,000 or less is preferably 10 to 50 wt%, preferably 20 to 39 wt%. In order to achieve sufficient performance, the molecular weight should be 10,000 or less, with a peak in the region of 2,000 or more (preferably 2,000 to 8,000), and a molecular weight of 15,000 to 100,000 (preferably 2,000 to 8,000). Preferably 20,000-70,000) A peak or shoulder is required in the +7) region. 2,000~10,00
There is no peak at 0 molecules, there is a peak at 112,000 or less, but the proportion of components with molecular sacs 10,000 or less is 50w
If it is larger than t%, problems such as blocking resistance, fusion to the photoreceptor, and filming will arise. Molecular weight 10.0
There is no peak below 00 (there is a peak above 10,000, but the proportion of components with molecular weight below 10,000 is 10wt)
If it is less than %, the generation of coarse particles also becomes a problem.

Further, if there is no peak or shoulder in the region of molecular weight over 15,000, and there is a peak only in the region of molecular weight less than 15,000, offset resistance becomes a problem.

If there is no peak or shoulder in the molecular weight region of 15,000 to 100,000, and a main peak is present in the region greater than 100,000, grindability becomes a problem.

Furthermore, the THF-insoluble content of the binder resin of the toner is preferably 10 to 70 wt%. THF insoluble content is 10
If it is less than wt%, offset resistance becomes a problem, and 70
If it is larger than wt%, problems of deterioration such as molecular chain scission due to heat kneading during toner production will occur. Preferably, the content of THF-insoluble matter is 15 to 49 wt%, which is good in terms of offset resistance.

The THF-insoluble content in the present invention refers to the weight percentage of the polymer component (substantially crosslinked polymer) that has become insoluble in the THF solvent in the resin composition in the toner, and refers to the weight percentage of the polymer component (substantially crosslinked polymer) in the resin composition in the toner. It can be used as a parameter indicating the degree of crosslinking.

The method for synthesizing the binder resin according to the present invention is preferably suspension polymerization, and basically a method in which two or more types of polymers are blended during synthesis is preferable.

That is, this is a method in which a first polymer that is soluble in THF and soluble in a polymerization monomer is dissolved in a polymerization monomer, and a 7-mer is polymerized to obtain a resin composition. In this case, a composition is formed in which the former and latter polymers are uniformly mixed.

The first polymer soluble in THF is preferably subjected to solution polymerization or ionic polymerization, and the second polymer for producing a component insoluble in THF is prepared under the conditions in which the first polymer is dissolved. It is preferable to synthesize by suspension polymerization or bulk polymerization in the presence of a crosslinking monomer. It is preferable to use 10 to 120 (preferably 20 to 100 parts by weight) parts by weight of the first polymer based on 100 parts by weight of the polymerizable monomer for producing the second polymer.

All known resins can be used as the binder resin in the present invention obtained by the method described above, but specific examples include styrenes, acrylic acids, methacrylic acids, and derivatives thereof. Those obtained by polymerizing one or more monomers are preferred from the viewpoint of development characteristics, charging characteristics, etc. Examples of monomers that can be used include styrene, α-methylstyrene, vinyltoluene, chlorostyrene, and the like. Acrylic acids, methacrylic acids, and their derivatives include acrylic acid, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, n-tetradecyl acrylate, and n-acrylate. hexadecyl,
Examples include acrylic esters such as lauryl acrylate, cyclohexyl acrylate, diethylaminoethyl acrylate, and dimethylaminoethyl acrylate, as well as methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, and methacrylate. Amyl acid, hexyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, decyl methacrylate, dodecyl methacrylate, lauryl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate , dimethylaminoethyl methacrylate, glycidyl methacrylate, and stearyl methacrylate.

In addition to the above-mentioned heptamers, small amounts of other heptamers such as acrylonitrile, 2-
Vinylpyridine, 4-vinylpyridine, vinylcarbazole, vinyl methyl ether, butadiene, isoprene, maleic anhydride, maleic acid, maleic acid monoesters, maleic diesters, vinyl acetate, etc. may be used.

Examples of crosslinking agents used in the toner of the present invention include divinylbenzene, bis(4-acryloxypolyethoxyphenyl)propane, ethylene glycol diacrylate, 1,3-butylene glycol diacrylate, and 1. Examples include 4-lyl phthalate, triallyl cyanurate, triallyl isocyanurate, triallyl isocyanurate, triallyl trimellitate, diarylchlorendate, and the like.

The selection of the initiator, type of solvent, and reaction conditions when producing the resin of the present invention are important factors in obtaining the resin targeted by the present invention. Examples of initiators include benzoyl peroxide, 1. 1-di(t-butylperoxy)-3
,3,5-)limethylcyclohexane, n-butyl-4
, 4-di(t-butylperxy)valerate, dicumyl peroxide, α.

Organic peroxides such as α'-bis(t-butylperoxydiisoprobyl)benzene, t-butylperoxycumene, and di-t-butylperoxide can be used.

In the present invention, the binder resin may be composed only of a resin having a small impurity content as described above, but the binder resin may also be a mixture with other resins.

Specific examples include styrene-acrylic copolymer resin, polyester resin, polyether resin, polyurethane resin, rosin-modified phenol resin, cellulose resin, and epoxy resin.

The toner of the present invention is made by containing other toner components, that is, fine magnetic powder and a charge control agent, in the particles that are more powerful than the binder resin, and optionally containing pigments or A coloring agent consisting of a dye and further additives such as a lubricant or a fixing aid are dispersed and contained. The particle size of the toner particles is generally 1 to 50 .mu.m, particularly preferably 3 to 20 .mu.m.

Specific examples of the magnetic fine powder mentioned above include metals made of ferromagnetic elements such as ferrite and magnetite, iron, cobalt, and nickel, or alloys or compounds containing these, or metals that do not contain ferromagnetic elements. , alloys that become ferromagnetic through appropriate heat treatment, such as manganese-copper-aluminum, or alloys of the type called Heusler alloys containing manganese and copper, such as manganese-copper-tin, or chromium dioxide, Others can be mentioned.

The content ratio of the fine powder of these magnetic substances is 1 part of the binder resin.
30 to 150 parts by weight is possible for 00 parts by weight,
Preferably it is 40 to 120 parts by weight.

In addition, in order to have stable and uniform charging properties and obtain excellent image characteristics, it is essential that the magnetic fine particles have good dispersibility in the binder resin. The bulk density value is 0.35g/mj! or more, preferably in the range of 0.5 g/mf or more. In particular, 0 for binder resins containing gel content.
, 6 g/m1 or more, particularly excellent dispersibility is exhibited. When the bulk density is less than 0.35 g/ml, the magnetic particles are not sufficiently dispersed in the binder resin, causing uneven distribution of the magnetic material, making it impossible to obtain sufficient development reproducibility.L)
. Here, a known technique such as a fret mill can be used to increase the bulk density. In addition, in this specification, bulk density (g/cc) is defined as JIS (Japanese Industrial Standard) K-5.
101.

The above-mentioned charge control agent is selected from conventionally known charge control agents. Specific examples of negative charge control agents include
No. 20153, No. 43-27596, No. 44-639
Metal complex salts of monoazo dyes described in No. 7, No. 45-26478, and JP-A-50-133338.
Nitrohumic acid and its salts or C
, 1,14645 and other dyes and pigments, Special Publication No. 55-4275
No. 2, Special Publication No. 58-41508, Special Publication No. 58-738
Co, C of salicylic acid, naphthoic acid, guicarboxylic acid described in No. 4, Japanese Patent Publication No. 59-7385, etc.
r.

Examples include metal complexes such as Fe, sulfonated copper phthalocyanine pigments, nitro groups, styrene oligomers into which halogens have been introduced, and chlorinated paraffins. In particular, metal complex salts of monoazo dyes, salicylic acid,
Metal complexes of alkylsalicylic acid, naphthoic acid, and guicarboxylic acid are preferred.

The amount of these charge control agents added is determined so as to maintain good triboelectric charging properties as described above, while minimizing adverse effects such as a decrease in developing power and a decrease in environmental stability due to contamination of the surface of the developing sleeve by the charge control agent. Binder resin 10 to suppress
The amount added is preferably 0.1 to 3 parts by weight relative to 0 parts by weight.

Specific examples of the colorant include any suitable pigments and dyes.

Examples of pigments include carbon black, aniline black, acetylene black, naphthol yellow, Hansa yellow, rhodamine lake, alizarin lake, red iron oxide, and phthalocyanine blue indanthremble. These are used in necessary and sufficient amounts to maintain the optical density of the fixed image, and are 0.1 to 2 parts by weight per 100 parts by weight of the resin.
The amount added is preferably 0 parts by weight, preferably 2 to 10 parts by weight.

Further, dyes are also used for the same purpose. For example, azo dyes, anthraquinone dyes, xanthine dyes,
Contains methine dyes, etc. 0.1% per 100 parts by weight of resin
The amount added is preferably 20 parts by weight, preferably 0.3 to 3 parts by weight.

Specific examples of the above additives include lubricants such as Teflon and zinc stearate, abrasives such as cerium oxide, silicon carbide, and strontium titanate, fluidity agents such as colloidal silica and aluminum oxide, anti-caking agents, Alternatively, conductivity imparting agents such as carbon black, zinc oxide, antimony oxide, tin oxide, etc.
Alternatively, there may be fixing aids such as low molecular weight polyethylene, low molecular weight polypropylene, various waxes, etc., or anti-offset agents. Further, a small amount of white fine particles and black fine particles of opposite polarity can be used as a developability improver.

The developer of the present invention can be manufactured by a conventional method. That is, fine magnetic powder is added to the binder resin described above.
After mixing the charge control agent or other additives and dispersing them using a Henschel mixer, for example, heat melt kneading is performed using a hot melt mixing device such as a twin screw extruder, and the resulting cooling mass is pulverized to form desired particles. Toner particles of the present invention are obtained by removing toner particles having a diameter range by air classification.

As described above, in the developer of the present invention, the main component of the binder resin is synthesized by suspension polymerization method.
Not only is it easy to manufacture, it is also easy to mix with magnetic fine powder, etc., and since the content of impurities due to initiator decomposition products in the binder resin is 2500 ppm or less, no adverse effects appear in practical use, and it has sufficiently good characteristics. It is possible to form good visible images over many times.

EXAMPLES Hereinafter, the present invention will be specifically explained using Examples, but these are not intended to limit the present invention in any way.

Synthesis Example: 70 parts of styrene in 200 parts by weight of toluene below the boiling point.
A mixed solution of 20 parts by weight of n-butyl acrylate, 10 parts by weight of α-methylstyrene, and 6 parts by weight of benzoyl peroxide was added dropwise over 5 hours, and then maintained below the boiling point for an additional 3 hours to polymerize. A low molecular weight polymer was obtained by vacuum drying to remove toluene. Next, 70 parts by weight of low molecular weight polymer, 75 parts by weight of styrene, 2 parts by weight of n-butyl acrylate
A homogeneous mixture of 4 parts by weight, 1 part by weight of divinylbenzene, and 4 parts by weight of benzoyl peroxide was suspended and dispersed in 300 parts by weight of water in which 0.8 parts by weight of partially saponified polyvinyl alcohol was dissolved, and the polymerization temperature was 80°C. Polymerization was carried out for 15 hours to obtain a resin in the form of crowbar-shaped fine particles in which a high molecular weight polymer including a gel component to a low molecular weight polymer were uniformly mixed, and the resin was dried under reduced pressure.

Approximately 0.5 g of the obtained particulate resin was accurately weighed, placed in a filter paper thimble (Toyo Roshi Model NQ, 86R), and subjected to Soxhlet extraction for 6 hours using 180 ml of chloroform as a solvent to extract the extracted soluble components. After evaporating to see the medium inside, it was vacuum dried at 100.degree. C. for 2 hours, and the amount of soluble resin component was weighed. The gel component weight (degree of crosslinking) was determined from the sample weight and this value according to the following formula.

That is, the gel component in the present invention refers to the weight proportion of a polymer component that has been crosslinked and becomes insoluble in a solvent in a resin composition, and is a parameter indicating the degree of crosslinking of a resin composition containing a highly crosslinked component. The sample resin amount was W+(g), the soluble resin component amount was W2(g), and calculations were made according to the following formula.

Gel component content” (W IW 2 ) /W 1X1
00 (%) Furthermore, this soluble resin component was dissolved in THF to prepare a sample having a concentration of 0.1% by weight, and the sample was passed through a sample pretreatment filter for non-aqueous systems to be used as a sample for GPC. GPC
5hodex K F-80M as a measurement column
using a GPC measurement device (150CA manufactured by Waters).
LC/GPC) installed in a 40°C heat chamber with a THF flow rate of 1 mj7/min and a detector under R1 conditions.
GPC was measured by injecting 200 μl of the sample.

The molecular weight is 0.5XlO'' as a calibration curve for molecular weight measurement.

2.35X10", io, 2X10", 35X10
", ll0XIO".

200X10", 470X103.1200X10"
, TH of 10 points of monodisperse polystyrene reference material (manufactured by Waters) of 2700 x 103° 8420 x lO''
F solution was used.

The gel component weight of the obtained particulate resin was 33% by weight, the molecular weight main peak value of the eluted component was 5,700, and the sub-peak value was 48,000. A chromatogram obtained by GPC is shown in FIG.

Further, the content of the polymerization initiator decomposition product was measured by a conventional method using a gas chromatograph-mass spectrometer (manufactured by HEWLETT PACKARD, 5890/TR10-1, manufactured by VG).

The content of polymerization initiator decomposition products in the obtained particulate resin was 6200 ppm.

A part of this particulate resin was divided and put into 201 distilled water, and 30 m of a sodium hydroxide aqueous solution with a specified concentration of 12N was added to this. was added and stirred for 20 minutes, thereby eluating and washing some of the impurities, and then an impurity removal process was performed by washing with water. The resin obtained here had an initiator decomposition product content of 3310 ppm.

A part of the resin thus obtained was divided and subjected to the same impurity removal treatment as described above, and the impurity content ratio was 2480.
ppm of resin was obtained.

After dividing a part of the resin in this way, the same impurity removal treatment was repeated two more times, resulting in a resin with an initiator decomposition product content of 1990 ppm and a resin with an initiator decomposition product content of 790 ppm.
of resin was obtained.

The content of initiator decomposition products obtained in the example of synthesis of 1 unit of seed was 62
00ppm, 3310ppm, 2480ppm,
1990ppm.

A total of 790 ppm of each of five types of resin was used as a binder resin, and 100 parts by weight and a bulk density of 1.05 g.
/ml of 60 parts by weight of magnetic fine powder (magnetite), 1 part by weight of a negative charge control agent (monoazo dye-based chromium complex), and 3 parts by weight of low molecular weight polyethylene wax, and cross-wired by a normal method. Grinding and classification were performed to obtain five types of toner having an average particle size of 12 μm.

(1) Test 1. (Actual photography test under normal temperature and humidity conditions) 0.4 parts by weight of hydrophobic colloidal silica was mixed with 100 parts of each of the toners obtained here to prepare a total of 5 types of developers, and each of them was commercially available. electrophotographic copying machine rFC-5J (
(manufactured by Canon) was modified and used.

In the copying machine used, a negatively charged organic photosensitive drum was used, and the surface potential (highest potential) of the organic photosensitive member during charging was -700 V, and the gap between the photosensitive member and the developing sleeve in the developing space ( Dsd) is 270 μm 1 The distance between the tip of the regulation blur and the developing sleeve (Dsb) is 240 μm
1 The magnet body is a fixed type, the magnetic flux density on the surface of the developing sleeve is 800 Gauss, and the thickness of the developer layer on the sleeve is 80 Gauss.
μm, AC bias 1800Vpp, 1400Hz
A photocopying test was conducted in which a copied image was formed by reverse development 5,000 times continuously while applying a DC bias of -450V to the sleeve, and the following items were evaluated. The results are summarized in Table 1 below.

(2) Image Density Using a "Macbeth Reflection Densitometer" (manufactured by Macbeth Co., Ltd.), the relative density of the white area of the original with a density of OoO to the copied image was measured.

(2) Fog Density The worst value of image fog was determined by measuring the relative density with respect to a white background area with a document density of 0.0 using a "Macbeth Reflection Densitometer" (manufactured by Macbeth). Note that the white background reflection density is 0.
It was set to 0.

Note that "image fog" refers to a phenomenon in which developer scatters on a white background area (non-image area).

(2) Image Quality Copied images were visually judged from five points: image scattering, image missing, image fading, image unevenness, and sharpness. The evaluation is "×" if it is poor and has practical problems, "△" if it is slightly poor but at a practical level, "○" if it is good, and "◎" if it is very good. ”.

"Image scattering" refers to a phenomenon in which developer scatters around the edges of an image, "image missing" refers to a phenomenon in which a part of an image is missing, and "image blurring" refers to a phenomenon in which a band-like difference in shading occurs in an image. "Image unevenness" refers to a phenomenon in which differences in shading occur in an image.

(2) Test 2 (live photo test under high temperature, high humidity conditions and low temperature and low humidity conditions) The environmental conditions were high temperature (30°C, 80% RH) and low temperature and low humidity (15°C, 10% RH). conducted the same live-action test and evaluated each of the above items. The results are summarized in Table 2 below.

(3) Test 3 (live-action test after storage for 6 months) After storage at room temperature and humidity for 6 months after adjusting the developer,
A real photo test was conducted, and each of the above items was evaluated, and the deterioration of the developer over time was evaluated.

The results are summarized in Table 1 below.

As is clear from the results in Table 1, the developer of the present invention comprising a binder resin in which the content of initiator decomposition products in the binder resin is 2500 ppm or less realizes stabilization of triboelectric charging characteristics, and the initial and Even when an image is continuously copied 5,000 times, a good image with high image density and clear image quality without image fog etc. can be obtained when the content of initiator decomposition products is 2000 ppm or less. Ta.

On the other hand, in a developer made of a binder resin having a content of initiator decomposition products of 2500 ppm or less, the image became unstable, resulting in a decrease in image density and image fog.

From the viewpoint of environmental stability, as is clear from the results in Table 2, the above tendency is remarkable. That is, when the content of initiator decomposition products is 2,500 ppm or less, image fog increases under low temperature and low humidity conditions, and when image forming processes are performed multiple times, image density gradually decreases. I got a blurry image. In addition, under high temperature and high humidity conditions, the triboelectricity becomes unstable, especially under the influence of humidity.In the early stages of image formation, there are no problems with separate installation, but image formation As you repeat
The image density decreased considerably and the image became noticeably blurred.

Furthermore, deterioration of the developer due to long-term storage was hardly observed when the content of initiator decomposition products was 2500 ppm or less, and was not observed at all when the content was 2000 ppm or less, and the initial characteristics of the developer were maintained.

Furthermore, the fixing properties and anti-offset properties were also satisfactory.

Example 2 Bulk density is 0.36g/m! ! A developer was prepared in the same manner as in Example 1 except for using the binder resin, and the developer was evaluated and studied.

As shown in Table 3.4, the content of initiator decomposition products in the binder resin is 2500 ppm or less, more preferably 200 ppm or less.
By using the developer of the present invention with a concentration of 0 ppm or less, stabilization of triboelectric charging characteristics is realized, and even when carrying out the initial and multiple image forming processes, clear image quality without fog etc. and image density can be maintained. It was possible to form a good image with high environmental stability. In addition, even after long-term storage, the initial properties were not lost.

Table Example 3 A developer was prepared in the same manner as in Example 1 except that magnetic fine particles having a bulk density of 0.29 g/mj7 were used, including the binder resin, and the developer was evaluated and studied.

As shown in Table 5.6, it can be seen that as the content of initiator decomposition products in the binder resin decreases, image density, image quality, and environmental stability improve.

When the content of the decomposition products is 2,500 ppm or less, good images can be obtained although there is some image fogging;
pm or less, images with high image quality, high density, and excellent durability were obtained. Furthermore, deterioration of the developer over time could be prevented.

Table 5 As explained above, by controlling the content of initiator decomposition products in the binder resin of the developer of the present invention to 2,500 ppm or less, stable and uniform charging properties can be achieved, and development faithful to the latent image can be achieved. I will finish it. That is, high image density can be obtained from the beginning without any rise in image density, and clear image quality without fogging can be maintained even when the image forming process is performed many times. In addition, it reproduces stable images that are not affected by changes in temperature and humidity, maintains its initial characteristics without deterioration even after long-term storage, and provides stable image quality.

[Brief explanation of drawings]

In the accompanying drawings, FIG. 1 shows a chromatogram related to Example 1, and FIG. 2 is an explanatory diagram showing a schematic cross-sectional view of a developing device using a one-component magnetic developer used in the actual photographic test in the example. It is. l...-component Magnetic developer 2...Blade 3...Sleeve 4...Photosensitive drum 5...Fixed magnet 6...Bias application means θ, f7, 5

Claims (1)

[Claims] Toner contains 2500 ppm of decomposed products of polymerization initiator
A developer characterized by containing the following polymer.