DE3249228T1 - MAGNETIC TONER - Google Patents

Description

The invention relates to a magnetic toner for developing electrostatic images, particularly on an electroconductive magnetic toner for development of electrostatic images in electrostatic recording or electrophotography, including of the pressure transfer process.

(Technical background)

According to the prior art, the so-called two-component system developer is used as the developer of electrostatic images which comprises a mixture of a carrier and a toner is used. This developer loads the carrier and the toner by friction by moving them to opposite polarities, the charged Toner electrostatically adheres to the electrostatic image, which has opposite polarity, causing the Development takes place. Therefore, only the toner is consumed when the development is repeated, whereby the ratio of the carrier to the toner changes. Out

for this reason it is necessary / in order to obtain sensible images to constantly add toner in order to achieve a constant Maintain the value of the mix ratio, including an intricate and costly toner addition device, is required. Also, the carrier deteriorates due to the adhesion of the fine toner powder to it Surface and the like during prolonged use, thereby causing undesirable phenomena such as a deterioration in image sharpness and an increase the background pollution. For this reason, the carrier must also be periodically replaced by a new one, which is annoying. The above-mentioned problems are not entirely overcome by a developer in whom a so-called coated carrier is used, the surfaces of the carrier particles being coated with a resin are coated.

To the disadvantages of the two-component system developer described above to remedy this, the so-called one-component system developer has been proposed, which does not contain a carrier. This developer comprises a magnetic toner which is a fine powder of magnetic material dispersed in a thermoplastic resin, optionally incorporating therein dispersed carbon black and / or dye, followed by pulverization.

The magnetic toners can be roughly classified into the so-called electrically conductive toner, which is a relatively low one Has resistance, and the so-called insulating toner, which has a relatively high resistance, classified will.

Essential factors that influence the image quality, if images are produced by the xerographic process, the respective developer and transfer properties represent As the development due to electrostatic induction by the electrostatic charges

occurs, the aforementioned electroconductive toner does not require any actual charge for the toner. There is therefore the advantage that no detrimental fluctuations in development due to constant There are fluctuations in its properties depending on the humidity, but there is the disadvantage that a blurring of the transferred image occurs due to a change in the electric lines of force when the toner image is transferred onto the transfer paper by an electrostatic transfer device. On the other On the other hand, the insulating toner has a true charge with the opposite polarity of the latent image charge and development occurs through electrical attraction between the true charge of the toner and the latent Image loading. Such an insulating toner has a disadvantage that developing properties owing to a constant fluctuation of the true charge of the toner depending on the humidity are bad, however, it has an advantage that a transmitted image without blurring can be obtained without causing noise The lines of electric force occur when the toner image is applied to the transfer paper with an electrostatic Facility is transferred. Such electrically conductive toner and insulating toner have developing properties and transmission properties which contradict each other, so that it is difficult to obtain stable, good quality images by development using one of these toners.

To solve this problem, for example, is a method been carried out in which on the one hand an electrically conductive magnetic toner for development and on the other hand, a resin-coated paper is used to prevent disturbance of the electric lines of force during transmission to prevent the transmission properties to improve. However, such a coated paper involves an additional workload connected, which leads to an increase in costs

32A9228

leads, whereby the original advantage of the transmission system, using normal paper is lost. As an alternative, attempts have been made to reduce the Improve development properties by using an iso-

5 ling toner is used.

For example, "goes from Japanese Patent Provisional Publication No. 31136/1978 outlines a development system in which the toner is charged and also a bias voltage is applied. From Japanese Patent Provisional Publications No. 118056/1978 and No. 22835/1979 goes a development process with a mixture of two Types of magnetic toners with different resistances. It continues from the preliminary Japanese Patent Publication No. 42141/1979 discloses a method in which developing properties are thereby improved that the toner layer is made extremely thin in the developing section, thereby reducing the gap between the photosensitive part and the toner carrier (e.g. a

20 non-magnetic sleeve) is reduced.

Even if an insulating magnetic toner is used, a significant improvement in developing properties can be achieved with the above-mentioned methods. can be performed, however, the area of the electrically conductive toner could not be reached so far. Furthermore the disadvantage remains that a developing device which is specially serviced is required and that the mixing ratio of the two kinds of magnetic toners having different electrical resistances changes after a number of copies. The inventors have already proposed an image developing method that is described in Japanese Patent Provisional Publication No. 168674/1981 to meet these To solve problems. This procedure includes execution a pressure transfer of a toner image, wherein an electrically conductive toner on an image carrier an intermediate transfer member is transferred and the toner

1 image by pressure transfer to the final transfer part

is thermally fixed. In this process, the development properties are excellent by the use of an electrically conductive toner in the development, whereby no destruction or distortion of the three-dimensional accumulated body of the toner image due to the application the pressure transfer method instead of the transfer method with an electrostatic device occurs, resulting in transferred images that faithfully match the original, so that both excellent Developing properties such as excellent transfer properties are present, i.e., a final image is good Quality can be obtained. However, if the images are generated continuously, the thermal ones will change

15 transmission conditions constantly depending on the

Changes in the temperature and humidity conditions of the atmosphere, as well as changes in the heating temperature of the image forming device, so that a good quality image cannot inevitably be obtained. For example the viscoelastic property of the toner to be transferred and to be fixed changes due to the change in temperature during thermal transfer, so that the softened toner does not hit the final transfer member in sufficient quantities (generally transfer paper) but at the intermediate transfer part remains, this residual image being transferred back to the photosensitive part or a transfer paper that is subsequently brought up or the like is transmitted, so that the so-called "offset" phenomenon occurs, whereby the

30 Image quality is deteriorating. Other disadvantages that occur

consist in the fact that the fixation of the toner image during the thermal transfer is insufficient or the three-dimensional accumulated bodies of the toner image are destroyed or deformed due to excessive fixation

35 becomes, which deteriorates the image quality.

In order to overcome the above-mentioned unexpected phenomenon, the inventors have made extensive studies

■ * -

on the influence of the thermal properties of the magnetic toner on the image quality and surprisingly found that the difference between the softening point and the softening starting temperature of the magnetic toner is related to the image quality, and based on this finding, the present invention has been accomplished.
(Explanation of the invention)
It is an object of the present invention to provide a magnetic toner which is suitable for pressure transfer, particularly pressure transfer using an intermediate transfer member, and which has stable operating characteristics without the occurrence of the "offset" phenomenon and good image quality on plain paper corresponding to a conventional developing system, regardless of the type of photosensitive member used.

This object of the invention can be achieved with a magnetic toner comprising a magnetic material and a binder resin and characterized in that the difference between the softening point and the softening starting temperature of the magnetic toner is at least 5 ° C.
25th

The present invention will now be described in detail.

According to the invention, the softening point of the magnetic Toner is defined as the temperature at h / 2, where h is the height of an S-curve in the plunger depression-temperature curve (Softening flow curve) of the flow tester when a sample of magnetic toner is measured and recorded in an amount of 1 cm using a flow tester according to the model of the "Society of Polymer Chemistry of Japan" (manufactured by Shimazu Seisakusho Co.) under reaction

conditions with a pressure of 20 kg / cm, a diameter of the nozzle of 1 mm, a length of the nozzle of 1 mm

and a temperature rise rate of 6 ° C / min. On the other hand, the softening onset temperature is determined to be the temperature at h / 10 by the above measurement method Are defined.

The present invention can, for example, by at least one of the three concrete measures listed below can be implemented.

That is, first, the invention can be accomplished by a toner

realized / which comprises a magnetic material and a binder resin and is characterized in that said magnetic material comprises a mixture of at least two types of magnetic material components, wherein

15 is the difference in oil absorption between at least two Types of magnetic material components is at least • 3ml / 100g.

Second, the invention can be practiced with a toner comprising a magnetic material and a binder resin and is characterized in that said binder resin is a mixture of at least two Types of resin components, at least two types of said resin components being capable of toners which have a softening point difference of 3 ° C or more when processed into toners are made by the respective components with equal amounts of the same material and / or the same electrical conductive material are used.

Third, the invention can be practiced by a magnetic toner that is a magnetic material Binder resin and an electrically conductive material and characterized in that said electrically conductive material comprises a mixture of at least two types of carbon black, the difference in oil absorption between at least two kinds of carbon blacks account for 15 ml / 100 g or more.

1 magnetic material.

According to the invention, the oil absorption relates to the lowest necessary amount of D.B.P. (Dibutyl phthalate), to make a constant amount (100 g) of a magnetic material into a paste.

The magnetic material used in the invention Toner used can be either conductive, semiconducting, or insulating. If it's conductive or semi-conductive, it is not necessary to incorporate an electrically conductive material into the magnetic material when it is in accordance with the invention is used as an electrically conductive material. However, this case is based on those according to the invention limited magnetic toners that have an electrical conductivity of 10 to 10 XX / cm in a direct current field of 1000 V / cm.

As a magnetic material used for the invention Magnetic toner can be used, known conventionally used magnetic material powder can be used can be used. In particular, these include metal powders made of cobalt, iron, nickel, etc., fine powders of metal alloys, for example metals such as aluminum, cobalt, copper, iron, lead, nickel, magnesium, Tin, zinc, gold, silver, selenium, titanium, tungsten and zirconium as well as mixtures thereof, metal oxides such as aluminum oxide, Iron oxide, nickel oxide and metal compounds containing the same, and particularly magnetic ferrites and mixtures thereof. These powders can be obtained in an amount of 10 to 80% by weight, preferably 35 to 65% by weight on the total amount of toner. Some of these may have the property of being electrically conductive Material or a dye, in which case the toner according to the invention is the toner according to the invention Problem solves without the addition of an electrically conductive material or a dye. It can also be magnetic Materials used are their surface with

1 titanium and silane couplers is modified.

The mixing ratio of the individual magnetic materials is different depending on the resin or the electroconductive material used and is not particularly limited, but they should be mixed so that the difference between the softening point and the softening start temperature is at least 5 ^° C., which is from can easily be determined by a person skilled in the art by means of an experiment.

The oil absorption of the magnetic material is also not subject to any particular limits, but it amounts to preferably 10 to 80 ml / 100 g in order to prevent the toner softening point from increasing, the difference being in oil absorption between the at least two types of the magnetic materials, which are not particularly limited, are preferred in practice is at least 5 ml / 100 g.

Binder resin

According to the invention refers to the same extent of the electrical Conductivity of the magnetic toner to the same order of magnitude as the electrical conductivity readings, which occur due to the toner according to the invention at a direct current electric field of 1000 V / cm, where the electrical mentioned in connection with the invention

Electrical conductivity is determined by placing a sample in

30 a measuring cell with a cross-sectional area of T cm ■. . ■ 2 "

(F cm) at a depth of 0.03 χ 0.08 cm (h cm)

with a pressure of 1 kg applied to the upper surface and the value of the current (i amps) measured when the applied voltage (V volts) is changed, the calculation being made according to the following formula:

electrical conductivity y (A / cm) =

As a binder resin for the magnetic Toner preferably used thermoplastic resins / for example styrene polymers or derivatives thereof, such as polystyrene, polyvinyltoluene and the like; Copolymers of styrene or derivatives thereof, such as styrene-butadiene copolymers, Styrene acrylic acid copolymers, styrene maleic anhydride copolymers and the like; Polyester resins, Acrylic acid resins, xylene resins, polyamide resins, ionomer resins, Ketone resins, terpene resins, phenol-modified terpene resins, Rosin, rosin-modified resins, maleic acid-modified Phenolic resins, petroleum type resins, starch grafts; Polyvinyl alcohol, polyvinyl pyrrolidone, etc. These resins can either alone or in a mixture in an amount between 30 and 65 wt .-%, based on the total amount of Toners, are used. In particular, styrene type resins and polyester resins are preferred in the present invention.

Also, the mixing ratio of the various resins in the present invention depends on the magnetic material and the electrically conductive material used, and is not particularly limited, but they should be mixed so that the difference between the softening point and the softening start temperature is at least 5 ⁰ C / which can easily be determined by a person skilled in the art through experiments.

Even when similar resins having different compositions or molecular weights are used, two or more kinds can be mixed to make a greater difference between the softening point and the softening starting temperature of the magnetic toner. The size of the difference between the compositions and the average molecular weights is not particularly limited, but any difference is possible as long as the above-mentioned temperature difference of the magnetic toner of at least 5 ^° C. is caused.

1 Electrically conductive material

According to the invention, the oil absorption relates to the lowest required amount of D.B.P. (Dibutyl phthalate) to convert a constant amount (100 g) of carbon black into a paste.

The carbon black has the advantage of keeping the sharpness and shine of the Image as the amount increases, and is preferred used.

The mixing ratio of carbon blacks with different oil absorptions, this varies depending on the resin used and is not subject to any particular restrictions

15, according to the invention, can be such that the difference

between the softening point and the softening start temperature is at least 5 ° C, this of one A person skilled in the art can easily be determined experimentally. The oil absorption of the carbon black is not particularly limited but it is preferably 400 ml / 100 g or less in order to increase of the toner softening point. As carbon black for the magnetic toner according to the invention furnace black, Carbon black or acetylene black can be used.

25 '' '.' ■■; '■■ //

Electrically conductive materials other than carbon black can be used can also be used in the magnetic toner of the present invention. To the other electrically conductive Materials include good electrically conductive materials,

30 like silver, copper, aluminum, iron, etc., electrical

conductive organic polymers, such as polymers that have ionic polar groups, paints in which metal particles dispersed in a vehicle, etc., and metallic soaps which are salts of organic acids such as stearic acid and alkali metals, alkaline earth metals and transition metals, either individually or as a mixture in one Amount used which is 1 to 30 wt .-%, based on the total amount of the toner is.

-W-

In the toner of the present invention, it is possible to use other additives, if necessary, such as property improving agents / dyes and agents for improving free flow properties. The property-improving agents, which are added to improve the so-called "offset" phenomenon, include mold release agents such as higher fatty acids and their derivatives, higher alcohols, paraffins, waxes, etc., which are in an amount of 0.2 to 20 wt. -%, based on the total amount of the toner, are used. The dyes for image sharpness control or color adjustment may be suitable known pigments or dyes. Typical examples are the nigrosine dyes, aniline blue, calcooil blue, chrome yellow, ultramarine blue, aniline yellow, methylene blue chloride, phthalocyanine blue, rose bengal and mixtures thereof. When these dyes are used, it is desirable to use them in an amount of 1 to 20 wt. -%, based on the total amount of the toner, to be used. As means for improving the free flow properties, SiO ₂ , TiO and Al ₃ O ₃ are preferably used in an amount which is between 0.05 and 10% by weight, based on the total amount of the toner.

Any combination of the toner components as described above can be used as long as the difference between the softening point and the softening start temperature is at least 5 ^° C. This combination can thus be appropriately varied according to the purpose of use. The preferred combinations of the toner components which are intended for the transfer of pressure with an intermediate printing part are given in the examples.

Physical properties of magnetic toner

The difference between the softening point and the softening start temperature is 5 ^° C. or more.

Ι The softening point of the magnetic toner which does not particularly restricted, is preferably at most 17O ⁰ C and at least 8O ⁰ C, most preferably 135 ⁰ C and at least 100 ° C, namely by heat to save energy costs in the fixing and a temperature increase in to prevent the copier.

The electrical conductivity of the magnetic toner of the present invention may be sufficient to behave as an electrically conductive toner in the system using the magnetic toner, but it is preferably 10 to 10 SL / cm when the DC electric field of 1000 V is applied /cm. As used herein, the term "electrical conductivity" has the same meaning as given above.

The magnetic toner of the present invention can have a particle size from 1 to 50 μ and particularly preferably from 7 to

20 30 u have. For a toner having a particle size

of less than 1 µ, there is a risk that the toner fouling phenomenon is caused on the image forming member, thereby contaminating the transfer paper can occur while a toner with a particle size

25 of more than 50 μ disadvantageously tends to be a
produce grainy image quality.

Mechanism of the invention

30 The mechanism that causes the difference between the softening point and the Erweichungsbeginntemperatur of the magnetic toner above-mentioned is at least 5 ⁰ C, wherein the magnetic toner of two oder.mehr types of magnetic materials, carbon black having

different oil absorptions and two or more kinds composed of binder resins with different softening points can be given as follows will.

-14-That is, with the magnetic toner, if any of the Components of the magnetic material, binder and Carbon black is a composition of a mixture of two or more kinds has been found through studies of the The inventors found that the difference between the softening point and the softening start temperature of the magnetic toner is characterized by the difference in the binding force or affinity force between the respective components enlarged, the difference being due to the oil absorption magnetic materials, carbon blacks and the softening point of the binder resin. So if there is a mixture of two in the same toner particles or more kinds of magnetic materials, carbon blacks with different oil absorptions, or binder resins with different softening points is present, the softening flow curve of the toner formed can be as The sum of the softening flow curves of the toners using the individual components can be reproduced. this As a result, it can be estimated that a broad curve can be drawn, i.e. the difference between the softening point and the softening start temperature becomes large.

On the other hand, when the difference between the softening point and the softening starting temperature of the toner of the present invention is at least 5 ° C, the mechanism for obtaining stable performance without an "offset" phenomenon and good images can be determined roughly as follows.
30th

It can be assumed that if the temperature of the transfer paper at the time of transfer between the toner softening point and the softening start temperature is considered lying, the state of the toner, such as the viscoelasticity, changes or deviates by a slight change or deviation in the temperature of the transfer paper when the difference between the two temperatures is low, whereby an increase

- \% -

1 stand is caused, in which the danger of the "offset" phenomenon as well as causing unevenness in image quality during operation.

Production Example · for the magnetic toner

The magnetic toner of the present invention can be any of known methods are produced, for example by the method in which a toner starting material all at once or in portions with a hot roller, a heated kneader or a heated co-kneader kneaded, cooled, crushed and classified, the process in which a toner raw material is used all at once or in portions in a suitable solution

15 medium is dissolved, dispersed or suspended, followed by a spray drying treatment, or different polycondensation processes, such as interlayer polycondensation, Suspension polycondensation or solution polycondensation and others.

. .

Application Example-1 of Magnetic Toner

When using the magnetic according to the invention Toner can transfer the obtained toner image one time subjected to an intermediate transfer part

be that in an intermediate position between a photosensitive Roller and a normal paper after the pressure transfer (typically adhesive transfer) is provided is thereby the magnetic toner of the present invention

SO adhered to the surface of the above intermediate transfer member by the adhesive force on the surface of the above intermediate transfer member and the Charging force acting on the magnetic toner image without affecting the dissolution properties of the magnetic toner

35 image to destroy, can be moved on, followed by a subsequent thermal transfer and a fixation on the final transfer medium, namely normal Paper, due to its viscoelastic changes. If he

ι ζ · -

if desired, it is also possible to subsequently carry out an additional heat setting in order to improve the fixing properties to improve.

This point will now be described in detail. The above-mentioned intermediate transfer member may be any one Material capable of transferring the toner, generally comprising at least the surface of the transfer member (Transfer layer) of natural rubber, urethane rubber, Styrene butadiene rubber, silicone rubber, ethylene propylene rubber and fluorine rubber. Of the Silicone rubbers are suitable those that are vulcanized at a low temperature or by room temperature vulcanization can be obtained. Said natural rubber is a conventional natural rubber, which is primarily Line consists of poly-cis-1,4-isoprene. The urethane rubber is a rubber that is made up of structural units with urethane bonds formed by the reaction of diisocyanate with Glycols or diamines are formed, for example commercially available Vulkollan (manufactured by Sumito-Bayer Urethane Co.)., Hipren (manufactured by Mitsui Toatsu Kagaku Co.), Despopan (manufactured by Sumitomo-Bayer Urethane Co.), Estan (manufactured by Goodrich Co.), and Adipren (manufactured by DuPont Co.). The styrene butadiene rubber is a copolymer of a styrene monomer and a butadiene monomer, generally with an enriched one Butadiene monomer component. Various types of silicone rubber can be used as silicone rubber, but in general methyl silicone rubber, methyl vinyl silicone rubber and methylphenyl silicone rubber are used. The fluorine rubber can contain fluorine atoms in a polymer molecule contain and, for example, an ethylene trifluorovinylidenefluorocopolymer, a propylene pentafluoro-vinylidene fluorine copolymer, a propylene hexafluoro-vinylidene fluorine copolymer (e.g. Baidon, manufactured by Du Pont Co.), an ethylene chloride trifluoro-vinylidene fluorine copolymer, a fluorine-containing nitroso rubber, 1,1-dihydroperfluorobutyl acrylate rubber etc. be.

As materials of the transfer layer can also

synthetic natural rubbers, (Califlex IR, manufactured from Shell Chemical Co.) / ethylene propylene rubber (Nodel, manufactured by Du Pont Co.), arylonitrile butadiene-5 Rubber (Hycar, manufactured by Nippon Zeon Co.), organic polysulfide rubber (Thiocol, manufactured by Thiocol Co.), acrylic ester copolymer rubber (Hycar 4021, manufactured by Goodrich Co.), organic polysiloxane rubber (Shinetsu Silicone, manufactured by Shinetsu 10 Kagaku Co.) and the like can be used.

The transfer layer, which consists of these materials, preferably has a smooth and highly elastic surface with a rubber hardness of 5 to 70 °.

Commercially available products are preferably used as silicone rubber, such as KE-40, 41, 42, 42S, KE-441, 44, 45, 45S, KE-471, 47, 48, KE-67, 103, 1205, 1206, 1300, 1600, KE-12, 16, 17, 62, 1091, 1093, 1400 (all of which are

20 temperature vulcanizable), KE-104, 106, 1201, 1202, 1204, KE-1212, 1800 (all of which are low temperature vulcanizable and manufactured by Shinetsu Kagaku Co.)

25 generally a transmission part is used that comprises the aforementioned transfer layer material on a substrate of a metal, for example a stainless steel, a nickel tape, etc., a polymeric film such as a polyester, polyimide,

Polyimidamide, polysulfone, etc.

In general, there is an upper limit on the amount of the toner adhering to these transfer parts. At-

■ '· ■■■■' ■■■ '■■. '2

For example, a maximum of 1.0 mg / cm of toner can be applied to the transfer layer with a thickness of 50 μ, which comprises a silicone rubber KE-1800 (rubber hardness 40 °), adhere. The image sharpness is 1.0 when the amount of the toner adhering to the transfer part is 0.7 mg / cm,

although the value may change depending on the salary of the Dye in the toner.

The transfer member can either be of the type of a roller which rotates together with the image forming part, as shown in FIG. 1, or an endless belt which runs over at least two revolving rollers which rotate with the image forming part, as shown in FIG. The transfer member having the toner image obtained by the toner of the present invention, which has been heated beforehand if desired, transfers the toner image to the transfer paper, the toner image being fixed into a permanent image simultaneously with or after the transfer. The fixing temperature may be the softening point of the toner of the invention + _ 5O ⁰ C, preferably the softening point of the toner + _ 30 ⁰ C, most preferably the softening point of the toner + _ 20 ⁰ C to be.

The image forming method which is preferably carried out with the toner according to the invention will now be carried out with reference to the drawings is described.

According to Figure 1, the electrostatic latent image, the generated on the electrostatic charge carrier 2a on the platen by the electrostatic image forming section 1 has been moved to the developing section 3. In the developing section 3, the toner of the present invention is used 3b is drawn to the roller 3a by a magnet placed in the roller 3a, and rotates to the electrostatic one Carrier 2a, which after it has been trimmed to a certain height with the serrated cutter 3c, exposed to the electrostatic latent image at a certain distance and counter charges at the tips The spikes are induced, the pillars of accumulated toner particles, by the electrostatic latent images while it is being framed directly in contact with it or moving past with a very narrow gap and is then brought into contact with it, whereby the toner

■ ' ■■ ■ ■■ -w- ^; · ■

particles in an amount proportional to the amount of charges of the electrostatic latent image, successively be moved in the direction of the latent image side, to give the toner image.

The toner image thus formed is placed on the transfer roller

transferred, with a contact of about 0.1 kg / cm with the

electrostatic charge carrier 2a is present, with a Tolerance of the structural strength of the three-dimensional

collected toner particles. The toner image is created with a Infrared heater 5 near the transfer point to the copy paper 7 heated to be demold, and transferred and fixed on the copy paper 7 between the transfer roller 4 and the pressure roller 6, which against the

15 said roller 4 is pressed.

The rotating roller 2, which transfers the toner image to the transfer roller 4, a static elimination treatment is given in Section 8 for Elimination subjected to static charges, the remaining toner is removed with a cleaning device 9 and then it is sent to the next process. In the device shown in Figure 1, the electrostatic charge image when the portion 1 to form an electrostatic latent image, the static eliminating section 8 and the cleaning means present in a non-actuated state, not destroyed during the transfer to the transfer roller 4, which enables so-called retention

30 is set to produce the same toner image.

The device shown in Figure 2 represents an embodiment represents in which a transmission tape is used as a transmission part. It's built so that the 35. The pressure vector of the toner against the three-dimensionally accumulated particles during the transfer is minimal. The toner image produced in a manner similar to the embodiment which are described in connection with FIG

-ΜΙ is, is formed, is by the transfer roller 10 transferred to the transmission belt 13, which is with a electrostatic charge carriers 2a at a pressure that

2
is set to about 0.15 kg / cm, is in contact.

The transfer belt 13 runs around the transfer roller 10, the pressure contact roller 11 and the tension roller 12, wherein the toner image on the electrostatic charge carrier 2a is transferred by applying pressure to the transfer belt 13 through pressure contact with the transfer roller 10 will. The transfer belt 13 that transfers the toner image has, is moved in the direction of the arrow, near the point of transfer to the copy paper 7 with an infrared heater 5 heated in order to be demoldable, whereby the image from the transfer belt 13 onto the copy paper 7 is transferred while passing through the pressure contact roller and the roller 6.

The device shown in Figure 2 is also capable of retention similar to the device shown in FIG.

The transfer belt 13 is after it has the toner image on the copy paper 7 has transferred, a cleaning of residual toner and paper dust of the copy paper on the Belt cleaning device 14 subjected, wherein the transmission belt 13 further a static discharge on the transfer surface of the tape with a static discharge device 15 can be subjected. A roller with a felt or the like can be used for cleaning their circumferential surface is provided, used, or a rubber knife or scraper made from a polymeric material or a metal.

A corona discharge device is often used as the static discharge device or a tape comprising electrically conductive fibers is used.

These belt cleaning devices and the static discharge

-34-

1 facilities are of course also included in the facility applicable, which is shown in FIG.

The magnetic toner of the present invention is particularly useful special for pressure transmission, but it is not limited to this, but also as an electrically conductive one Toner can be used for other general purposes.

(Brief explanation of the drawings)

The drawings show typical examples of an apparatus for the pressure transmission process for which
the toner of the present invention is suitable. Figure 1 shows
an embodiment in which a sticky, adhesive transfer roller is used and FIG. 2 an embodiment in which a sticky, adhesive transfer tape is used.

(Best embodiment for carrying out the invention)

To further illustrate the magnetic toner of the present invention, examples are given below, however
the embodiments according to the invention are not limited thereto. In the following description, "parts" represent "parts by weight" unless otherwise specified.

example 1

Binder resin; Styrene butyl acrylate copolymer
(77:23) 40 parts

magnetic materials; (1) trade name

MG-W H-81-0402
(oil absorption 25 ml / 100g) 20 parts

(2) Trade name MG-W H-81-0401

(Oil absorption 30ml / 100g) 20 parts

(3) Trade name MG-W H-81-0518
(oil absorption 35 ml / 100 g) 20 parts

(all made by Mitsui
Kinzoku Co.)

-dt ** · -ΜΙ soot; Trade name Conductex SC

(manufactured by Columbia Carbon Co.) 15 parts

The above materials were well mixed and then kneaded by a kneader at 150 to 16O ⁰ C for 30 minutes. After cooling, the mixture was crushed into a powder by a conventional method and classified to obtain a toner of the present invention having an average particle size of 13.6 µm (hereinafter referred to as toner A).

Then, instead of the above-mentioned magnetic materials, 30 parts of MG-W H-81-0402 (trade name) (oil absorption 25 ml / 100 g) and 30 parts of MG-W H-81-0401 (trade name) (oil absorption 30 ml / 100 g ) are used, under otherwise the same conditions as in the above process, in order to obtain a toner according to the invention which has an average particle size of 13.7 μ (hereinafter referred to as toner B ₁ ).

Furthermore, instead of the above magnetic materials, 50 parts of MG-W H-81-0518 (trade name) (oil absorption 35 ml / 100 g) are used under otherwise the same conditions as in the above method to obtain a comparative toner with an average diameter of 13.6 μ (hereinafter referred to as toner C ₁ ).

The characteristic values of the toners A ₁ , B ₁ and C. obtained therewith are shown in Table 1.

Table 1

^^. Toner: Toner A ₁ Toner B 1 Toner C ₁ Characteristic \.
Values: ^ \ Softening point ( ⁰ C) 130 129 138 Onset of softening
temperature ( ⁰ C) 121 123 134 Electrical cond
capability
(a / cm) 3.6 χ 10 " ⁶ 3.8 χ 1 3.2 χ 10 ~ ⁶

As is clear from this table, it can be understood that the difference between the softening point and the softening starting temperature of a magnetic toner can be made higher by adding a mixture of magnetic materials with different oil absorption is used.

Running tests were carried out on an apparatus as shown in Fig. 2 using the aforementioned toners A ₁ , B ₁ and C ₁ , to obtain results relating to the "offset" properties shown in Table 2 . The photosensitive member used was selenium and the transfer member used was an endless belt comprising a polyimide substrate coated with a silicone rubber. Likewise, the roll was set to 6 145 ⁰ C, the roller 11 on the other hand to 12O ⁰ C.

= 14 table 2

10

number of 1 - 100 2000 5000 10,000 20000 Copies: Toner: v. very good very good very good very good Well Toner A ₁ very good very good very good Well Well Toner B ₁ very good Well normal bad very
bad Toner C ₁

15th

As can be seen from Table 2, the invention magnetic toner (toner A and toner B) good, namely without the "offset" phenomenon.

Example 2

20th

Binder resin: polyamide resin (trade mark:

Barsamide 940 manufactured by
Nippon General Mills Co.)

40 parts

25 30

Magnetic
Materials:

Soot:

(1) Trade name RB-BL

(Oil absorption 22 ml / 100 g) 30 parts

(2) Trade name BL-200

(Oil absorption 28 ml / 100 g) 30 parts (both are made by
Titanium Kogyo Co.)

Trade name Ketchen EC

(manufactured by Lion Yushi Co.) 7 parts

35

The above materials were well mixed and then treated in the same manner as described above to obtain a toner of the present invention having an average particle size of 14.0 µm (hereinafter referred to as toner D ₁ ).

Then the same procedure is repeated except that 30 parts are substituted for the above materials RB-BL can be used to produce a comparative toner having a mean particle size of 13.9μ (hereinafter referred to as Toner E. is designated).

Furthermore, the same procedure is repeated except that the magnetic materials mentioned above are replaced 60 parts of BL-200 are used to produce a comparative toner having an average particle size of 13.8μ (the following referred to as Toner F.).

The characteristic values of the toners obtained here

E. and

are given in Table 3.

Table 3

^ -v ^ Toner:
Characteristic
table values :. Toner D. Toner E ₁ Toner F ₁ Softening
point ( ⁰ C) 114 112 117 Softening restriction
starting temperature
( ⁰ C) 108 110 113 Electric
Conductive
speed (n / cm) 8.6 χ 10 ~ ⁶ 9.0 χ 10 ~ ⁶ 8.8 χ 10 ~ ⁶

As can also be seen from Table 3, it can be seen that the difference between the softening point and the softening start temperature A magnetic toner can be made larger by using two or more magnetic materials can be used with different oil absorptions.

-ΜΙ Using the toner D, E and F. _1, images were formed by the same apparatus as used in Example 1 (however, the roller 6 was set to 13O ⁰ C and the roll 11 to 100 ⁰ C and the photosensitive member was replaced by OPC), the toner D ₁ exhibiting good running properties and giving good image quality.

The above photosensitive part OPC was manufactured / by one part by weight of Chlorodian Blue (bis-azo pigment) in 140 parts by weight of a 1.2: 1.0: 2.2 mixture of ethylenediamine, n-butylamine and tetrahydrofuran was dissolved and the solution was applied in such an amount was that after drying 1 μ adhered to form a carrier-forming layer, whereupon 6 parts by weight i-phenyl-3- (p-diethylaminostyry1) -5- (p-diethylaminophenyl) pyrazoline and 10 parts of a polyester "Byron 200" (manufactured by Toyo Boseki Co.) in 90 parts by weight 1,2-dichloroethane was dissolved, followed by application of the formed solution to a film thickness of 10 μ after drying to form a carrier transport layer, whereby an electrophotographic photosensitive member is formed would.

Example 3

Example 1 was repeated except that 10 parts of styrene butyl acrylate resin (70:30) in place of the binder resin of Example 1 and a mixture of 30 parts of a magnetic material (trade name RB-BL, manufactured by Titanium Kogyo Co., oil absorption 22 ml / 100 g) and 30 parts of another magnetic material (trade name BL-SP, manufactured by Titanium Kogyo Co., oil absorption 25 ml / 100 g) were used in place of the magnetic material mixture, whereby a toner according to the invention having an average particle size of 14.8 μ ( hereinafter referred to as toner G ₁ ).

For comparison, there were 30 parts of a magnetic material

-W-

(Trade name BL-SP, manufactured by Titanium Kogyo Co., oil absorption 25 ml / 100 g) and 30 parts of another magnetic material (trade name SP-20, manufactured by Titanium Kogyo Co., oil absorption 23 ml / 100 g) was used in place of the above-mentioned magnetic material, whereupon otherwise the same procedure as described above was used to prepare a toner for comparison having an average particle size of 14.9 μ (hereinafter referred to as toner H ..).

The characteristic values of the toner G ₁ and the toner

are shown in Table 4.

Table 4

"\ ^ Toner:
Characteris
table values: - ^ Toner G ₁ Toner H ₁ Softening
point ( ⁰ C) 124 125 Softening
starting temperature
( ⁰ C) 119 121 Electric
conductivity
(Λ / cm) 5.8 χ 10 " ⁶ 3.8 χ 10 ~ ⁶

As can be seen from Table 4, it can be seen that the difference between the softening point and the softening start temperature a magnetic toner to 5 ° C or more by a combination of two or more magnetic materials with a difference in oil absorption can be set from 3 ml / 100 g or more,

Operation tests were also performed by this toner were used, similarly to Example 1, wherein the roll 11 to 115 ° C and the roller 6 were set to 140 ⁰ C. It was found that the "offset" phenomenon was _{noticeably observed in about 10,000 copies for the toner H 1} , but essentially no "offset" phenomenon was observed for the toner G-.

Example 4 10

Binder Resins: (1) styrene-butyl methacrylate copolymer

(60: 40)

(Softening point: 11O ⁰ C) 30 parts

(2) Polyamide resin (trade name Barsamide

940 manufactured by Nippon Generalmils Co.) 10 parts

Magnetic material: trade name BL-100 (manufactured by Titanium Kogyo Co.) 60 parts

Carbon black: trade name Ketchen EC (manufactured by

Lion Yushi Co.) 7 parts

The above materials were mixed well and then treated in the same manner as described above, to a toner according to the invention having an average particle size of 13.6μ (the following referred to as toner A ").

Subsequently, 40 parts of the styrene-butyl methacrylate copolymer (60:40) was used in place of the above resin, otherwise the same procedure as described above was carried out to obtain a comparative toner having an average particle size of 13.5 µm (the one below referred to as toner B ₂ ).

3248228

-S-9-

Furthermore, 40 parts of the polyamide resin (trade name Barsamide 940) is used instead of the resin given above, otherwise the same procedure as above was carried out to obtain a toner for comparison having an average particle size of 13.6 µ (hereinafter referred to as Toner C " will get).

The characteristic values of the toner A thus obtained

10 B- and C_ are given in Table 5,

Table 5

N. Toner:
Characteris
table values: ^ Toner A ₂ Toner B ₂ Toner C ₂ Softening
point ( ⁰ C) 132 138 111.5 Softening
starting temperature
( ⁰ C) 125 134 109 Electric
conductivity
(A / cm) 3.3 χ 10 ~ ⁶ 3.1 χ 10 ~ ⁶ 3.0 10 ~ ⁶

Table 5 also shows that the difference between the softening point and the softening start temperature can be seen of a magnetic toner can be made larger when two or more binder resins are mixed will.

Example 5

Binder Resins: (1) styrene butyl acrylate copolymer

(80: 20)
(Softening point 105.6 ⁰ C) 20 parts

(2) styrene butyl acrylate copolymer (75:25)
(Softening point 102.2 ⁰ C) 20 parts

Magnetic material: trade name BL-120 (manufactured by Titanium Kogyo Co.) 60 parts

Carbon black: trade name Ketchen EC

(manufactured by Lion Yushi Co.)

7 parts

The above materials were mixed well and then treated in the same manner as described above to obtain a toner of the present invention having an average particle size of 13.7 µm (hereinafter referred to as toner D ₂ ).

Then, 40 parts of the styrene-butyl acrylate copolymer (80:20) was used in place of the above-mentioned binder resins, followed by the same procedure as that described above to obtain a comparative toner having an average particle size of 13.6μ (the one below referred to as toner E ₂ ).

In addition, 40 parts of the styrene butyl acrylate copolymer (75:25) were used, otherwise the same The manner as described above was operated to prepare a toner for comparison purposes having an average particle size of 13.8 µ (hereinafter referred to as toner F_).

The characteristic values of the toners E ₂ and F- thus obtained are shown in Table 6.

Table 6

10 15 20

NToner:
Characteris ^ v
table values:>. Toner D ₂ Toner E " Toner F " Softening
point ( ⁰ C) 151 151 148 Onset of softening
temperature ( ⁰ C) 146 147 144 Electrical cond
ability (H / cm) 8.8 χ 10 " ⁶ 9.3 χ 10 ~ ⁶ 8.9 χ 10 ~ ⁶

Table 6 also shows that the difference between the softening point and the softening start temperature can be seen of a magnetic toner can be made larger by mixing two or more similar resins provided that there is a different ratio of the components.

30 35

Example 6

Binder Resins: (1) Polyester resin 24 parts

(Copolymer with a mole ratio of terephthalic acid: fumaric acid: Bisphenol A of 1: 1: 2; weight average molecular weight: 2600, number average molar mass: 2062; softening point of 105 ⁰ C)

Carbon black: trade name Conductex 975

(manufactured by Columbia Carbon Co.) (oil absorption 160ml / 100g)

10 parts

The same treatment as in Example 1 was carried out on the above materials to prepare a toner of the present invention having an average particle size of 13.8μ (hereinafter referred to as Toner I ₃ ).

Then, the same procedure was repeated except that 7 parts of Ketenen EX (manufactured by Lion Yushi Co.) was used in place of 10 parts of the above Conductex 975 to produce a toner of the present invention having a mean particle size of 13.5 µm (the one below referred to as J ₃ ).

The characteristic values of the toners obtained in this way I_ and J_ are given in Table 8.

Table 8

^ "\ ^^ Toner:
Characteristic
Values: ^^ - \ ^ Toner I3 Toner J Softening point
( ⁰ C) 127 140 Onset of softening
temperature ( ⁰ C) 122 126 Electrical cond
ability {SI / cm) 2.6 χ 10 ~ ⁶ 3.3 χ 10 " ⁶

-Μι example 8

Binder resin: styrene resin 40 parts

(Trade name Piccolastic D-125, manufactured by Shell Chemical Co.,

weight average molecular weight / number average Molecular weight = 45)

Magnetic material: trade name BL-100 60 parts

(manufactured by Titanium Kogyo Co.)

Carbon black: trade name Ketenen EC 7 parts

(manufactured by Lion Yushi Co.) (oil absorption 313ml / 100g)

The same treatment as in Example 1 was carried out on the above materials to obtain a magne-20 table toners with an average particle size of

14.0 µ (hereinafter referred to as Toner K ₃ ).

Then the above procedure was followed 25 is repeated except that 8 parts of Conductex SC (manufactured by Columbia Carbon Co.) are substituted for the above carbon black to obtain a magnetic toner for comparison having a mean particle size of 14.2 µm (hereinafter referred to as Toner L-.). 30th

The characteristic values of the toners K ₃ and L ^ thus obtained are shown in Table 9.

Table 9

^ """■" - ■ ^^ Toner:
Characteristic
Values: ^^ \ ^^ Toner K- Toner L ₃ Softening point
( ⁰ C) 117.5 115 Onset of softening
temperature ( ⁰ C) 107.5 111 Electrical cond
ability (/ cm) . 3.3 χ 10 ~ ⁶ 5.2 χ 10 ~ ⁶

It can also be seen from Tables 8 and 9 that it can be seen that the difference between the softening point and the softening starting temperature can be made considerably larger by using only one kind of binder resin having a large molecular weight distribution.
Example 9

Using the toners A ^ to L ", which according to the examples 4 to 8 were obtained, running tests were carried out in the same manner as in Example 1 to find the results shown in Table 10 in terms of "offset" properties. The roller temperatures used are also given in Table 10.

ω O

to O

Table 10

Number of copies: 1-100 2000 5000 10,000 20000 Roller temperature ( ⁰ C) Roller 11 Toner: ^ "^ -« ^ very good very good very good very good Well Roller 6 120 Toner A ₂ very good very good Well normal bad 145 125 Toner B_ bad bad bad very
bad - 150 100 Toner C ₂ very good very good very good Well Well 130 140 Toner D very good very good Well normal bad 165 140 Toner E » very good very good Well normal bad 165 140 Toner F_ very good very good very good very good Well 165 120 Toner G ₂ moderate bad bad very
bad very
bad 145 100 Toner H ₂ very good very good very good Well normal 130 120 Toner I ~ very good very good very good very good Well 145 130 Toner J ₂ very good very good very good Well Well 155 100 Toner K ₂ Well normal bad very
bad very
bad 120 100 Toner L ₂ 130

ro ro oo

From Table 10 it can be seen that the inventive Good quality toner images without the "offset" phenomenon results.

At the surface potential of the photosensitive part, the was used in this experiment, the toner according to the invention also showed only very slight fluctuations repeated use.

10 comparative example

Binder resin: polyamide resin

(1) Trade name Barsamide 940 20 parts

(manufactured by Nippon Generalmills Co.)

(2) Trade name Barsamide 930 20 parts (manufactured by Nippon Generalmills Co.)

Magnetic material: trade name BL-100 60 parts

(manufactured by Titanium Kogyo Co.)

Carbon black: trade name Conductex 975

(manufactured by Columbia Carbon Co.)

10 parts

A magnetic one was obtained by following the same procedure as in Example 1 using the above materials Toner obtained for comparison (hereinafter referred to as Toner M ~).

Further, instead of the above-mentioned binder resins, 40 parts of Barsamide 940 and Barsamide 930 were used separately, and the same procedure was carried out to obtain magnetic toners for comparison (hereinafter referred to as Toner N ₀ and Toner O_, respectively).

1 These toners have the characteristic values shown in Table 11 are given.

Table 11

^ "- ^ Toner:
Characteristic
Values: ^^^ - ^ Toner M_ Toner N_ Toner O " 10 Medium particles
size (μ) 13.6 13.8 13.5 15th Softening point
( ⁰ C) 111 112 114 Onset of softening
temperature ( ⁰ C) 107 110 112 20th Electrical cond
ability (g / cm) 3.3 χ 10 ~ ⁶ 3.9 10 ~ ⁶ 3.7 10 ~ ⁶

From Table 11 it is clear that if the difference in softening point between the magnetic toners were prepared from individual binder resins is less than 3 ° C, the difference between the softening point and the Erweichungsbeginntemperatur is at most 4 ⁰ C, even if these resins can be used in combination. The results of running tests carried out on these toners in a manner similar to that described above showed little effect when used in combination and practically none at all

35 appropriate extent.

Example 10

Binder resin: styrene butyl acrylate copolymer

(77: 23)

40 parts

-ΑΛ Ι Magnetic material: trade name BL-100 60 parts

(manufactured by Titanium Kogyo Co.)

Carbon black: (1) trade name Conductex SG 3 parts

(oil absorption 110 ml / 100 g)

(2) Trade name Conductex 975 4 parts (oil absorption 160 ml / 100 g)

(3) Trade name Conductex 1528 3 parts

(Oil absorption 220 ml / 100 g) (all manufactured by Columbia Carbon Co.)

5 The above materials were mixed well, followed by the same treatment as described above to obtain a toner of the present invention having an average particle size of 13.7 µm (hereinafter referred to as toner A ₃ ).

Then, instead of the carbon blacks specified above, three parts of Conductex SC and 7 parts of Conductex 975 were used, otherwise the procedure was the same to produce a toner according to the invention with a mean particle size of 13.8 μ (hereinafter referred to as Toner B, designated).

Likewise, instead of the above-mentioned carbon blacks eight parts of Conductex 1528 were used, after which the same procedure was otherwise followed in 3Q to obtain a toner for comparison purposes having an average particle size of 13.7 µm (hereinafter referred to as Toner C).

The characteristic values of the toners A ₃ , B ₃ and C ₃ thus obtained are shown in Table 12.

-UA- Table 12

Toner: Characteristic 5 values:

Toner A-

Toner B.

Toner C.

Softening point ( ⁰ C)

131

132

133

Softening start temperature ( ⁰ C)

122

126

129

Electrical conductivity (χι / cm)

2.6 χ 10 " ⁶ j 2.5 χ 10 ~ ⁶ ^ 2.6 χ 1θ" ⁶

Table 12 also shows that the The difference between the softening point and the softening starting temperature of a magnetic toner is made larger by using a mixture of carbon blacks having different oil absorption.

Example 11

Binder resin: polyamide resin 40 parts

(Trade name Barsamide 940, manufactured by Nippon Generalmills Co.)

Carbon blacks: (1) trade name Ketchen EC 3 parts

(manufactured by Lion Yushi Co.) (oil absorption 313ml / 100g)

(2) Trade name Conductex 975 5 parts

(manufactured by Columbia Carbon Co.) (oil absorption 160-ml / 100 g)

-4a-

Magnetic material: trade name BR-RL

(manufactured by Titanium Kogyo Co.)

60 parts

The above materials were mixed well and then treated in a manner similar to that described above, to a toner according to the invention with a medium Molecular weight of 13.8 μ (hereinafter referred to as toner D_ is designated).

Then 7 parts of ketenene EC are used instead of the carbon blacks specified above, after which otherwise the same The way to proceed is to use a toner for comparison purposes with a mean particle size of 13.6 μ (the hereinafter referred to as toner E_).

Furthermore, 10 parts of Conductex 975 are used in place of the above carbon blacks, and otherwise the same procedure is followed to obtain a toner for comparison purposes with a mean particle size of 13.8μ (hereinafter referred to as toner F ₃ ).

Table 13 shows the characteristic values of D ₃ ,

E and

Table 13

^^ \ ^^ Toner:
Characteristic
Values: ^ " ^v ---- ^ _ ^ Toner D ₃ Toner E ₃ Toner F ₃ Softening point
( ⁰ C) 110 112 111 Onset of softening
temperature ( ⁰ C) 105 110 109 Electrical cond
ability (ii / cm) 8.8 χ 10 ~ ⁶ 9.0 χ 10 ~ ⁶ 9.2 10 ~ ⁶

Example 12

Using the toners A ₃ - F _{3 obtained in} Examples 10 and 11, running tests were carried out in a similar manner to Example 1 to obtain the results shown in Table 14 on "offset" properties. The roller temperatures used are also given in Table 14.

ω ο

to O

CJi

Table 14

Number of copies: 1-100 2000 5000 10,000 20000 Roller temperature ( ⁰ C) Roller 11 Toner: "" "" - «» ^^^ very good very good very good very good Well Roller 6 120 Toner A ₃ very good very good very good Well Well 145 120 Toner B ₃ very good Well normal moderate bad 145 120 Toner C ₃ very good very good Well Well Well 145 100 Toner D-. bad bad - - - 130 100 Toner E ₃ bad bad - - - 130 100 Toner F ₃ 130

It can be seen from Table 14 that the magnetic toners _{according to the invention (toners A 3} , B ₃ and C ₃ ) have no "offset" phenomenon, so that images are produced which are stable and of good quality.

At the surface potential of the photosensitive part, the was used in this example, the magnetic toners also showed very little fluctuation repeated use.

Example 13

Binder resin: styrene butyl acetate copolymer 40 parts

(70: 30)

Magnetic material: trade name BL-100 60 parts

(manufactured by Titanium Kogyo Co.)

Carbon blacks: (1) trade name Larben C globules 7 parts

(manufactured by Columbia Carbon Co .; oil absorption 120 ml / 100 g)

(2) Trade name Larben 1040 7 parts

25 (manufactured by Columbia Carbon Co .;

Oil absorption 105 ml / 100 g)

The above materials were well mixed with stirring and treated in a similar manner to Example 1 to obtain a toner of the present invention having an average particle size of 13.6 µm (hereinafter referred to as Toner G ₃ ).

For comparison, instead of the carbon black, the above stated composition, a mixture of 8 parts of Larben 1200 (manufactured by Columbia Carbon Co .; oil absorption 72 ml / 100 g) and 8 parts of Larben 1170 (manufactured by Columbia Carbon Co .; oil absorption 58 ml / 100 g) used,

-AA-

after which the procedure was otherwise in the same way to a toner for comparison purposes having an average particle size of 13.7 µ (hereinafter referred to as toner H- will get).

The characteristic values of the toners G ₃ and H ₃ are shown in Table 15.

Table 15

^^ V. Toner:
Characteristic
Values: ^ "\. Toner G ₃ Toner H_ Softening point
( ⁰ C) 123 122 Onset of softening
temperature ( ⁰ C) 118 118 Electrical cond
ability (jfL / cm) 2.8 χ 10 " ⁶ 5.3 χ 10 ~ ⁶

Table 15 it can be seen that visible the difference between the softening point and the Erweichungsbeginntemperatur of the magnetic toner not 5 ⁰ C or may be higher when a combination of two or more carbon blacks with a difference of the oil absorption of less than 15 ml / 100 g is used.

When the operating tests were carried out in a manner similar to that in Example 1 using toners G ₃ and H ₃ , the "offset" phenomenon _{clearly occurred after 100,000 copies for toner H 3} , while no "offset" phenomenon was observed _{for toner G 3.}

Reference oak Explanation

1 section to form a

electrostatic latent image

2 roller

2a Electrostatic charge carrier

3 developing section 3a developing sleeve

3b Magnetic toner

3c serrated cutter

4 transfer roller

5 infrared heating

6 pressure roller

7 copy paper

8 Elimination section

static charge

9 cleaning equipment

10 transfer roller,

11 pressure roller

12 tension roller

13 Transfer tape

14 Belt cleaning device

15 Elimination section

static charge

Claims (11)

1 claims: 1. A magnetic toner comprising a magnetic material and a binder resin, characterized in that the difference between the softening point and the softening start temperature of the magnetic toner is at least 5 ^° C. 2. Magnetic toner according to claim 1, characterized in that it is an electrically conductive substance contains. 3. Magnetic toner according to claim 1 or 2, characterized in that that it is a pressure transfer toner. 4. Magnetic toner according to claim 3, characterized in that that the pressure transmission is a system using an intermediate transmission part. 5. Magnetic toner according to claim 4, characterized in that that by the pressure transfer an image on the intermediate transfer member to the final transfer member is transferred simultaneously with the thermal fixation. 6. Magnetic toner according to claim 1 or 2, characterized in that that the magnetic material is a mixture of at least two kinds of magnetic material components and the difference in oil absorption between at least two kinds of the magnetic materials 30 is at least 3 ml / 100 g. 7. Magnetic toner according to claim 6, characterized in that the magnetic material components a have oil absorption of 10 to 80 ml / 100 g. 8. Magnetic toner according to claim 1 or 2, characterized characterized in that the binder resin comprises a mixture of at least two kinds of resin components 1 and at least two kinds of the resin components are able to form toners in which the difference in softening points is at least 3 ⁰ C when they are processed into toners by the respective Components with equal amounts of the same magnetic material and / or the same electrical conductive material are used. 9. Magnetic toner according to claim 2, characterized in that the electrically conductive material carbon black is. 10. Magnetic toner according to claim 9, characterized in that that the electrically conductive material comprises at least two types of carbon black and the difference of oil absorption between at least two types of carbon black thereof is at least 15 ml / 100 g. 11. Magnetic toner according to claim 10, characterized in that that the oil absorption of the soot components is at least 400 ml / 100 g.