JPS5895750A - Pressure fixing type magnetic toner - Google Patents

Abstract

PURPOSE:To obtain pressure fixing type magnetic toners having the excellent fixing property in an easily visible picture without luster even by a normal fixing roll, by using amide wax and ethylene ethyl acrylate as main resin components. CONSTITUTION:Amide wax is used as wax and a mixed resin in which ethylene ethyl acrylate (EEA) is added is used as main resin components for a titled pressure fixing type magnetic toner. The compounding amount of them is arranged so that the ratio of amide wax to EEA in a CPC system is made to be in the range of 4/6-8/2 by weight. Polypropylene and silicone varnish are also used as resin components besides them. The substance having the range of 25-55pts.wt. magnetic powder in 100pts.wt. toner is preferably used and powders such as magnetite, ferrite, Hi and Cr are used.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pressure fixing type magnetic toner used for developing electrostatic latent scratches in electrophotography, electrostatic recording, and the like.

In copying systems using electrophotography and electrostatic recording, it has not been put to practical use to use a one-component magnetic toner as a developer to develop electrostatic latent scratches formed on the surface of a photoreceptor or dielectric material. There is. This type of copying method can be broadly divided into the so-called CPC method, which uses ZnO paper or electrostatic recording paper as an electrostatic latent scratch carrier and directly fixes it after preparation, and the developed image that is transferred onto a transfer sheet such as plain paper. The so-called PP that settles after
It is divided into C method.

In the CPC method or PPC method using the above-mentioned magnetic toner, a heating fixing method using a heater or a heat roller has been known as a fixing method, but it is possible to eliminate the waiting time for fixing preheating and A pressure fixing method has also been developed and put into practical use with the aim of saving power consumption.

The magnetic toner used in this type of pressure fixing method is
For example, those using wax and thermoplastic resin as resin components as described in JP-A-50-50042;
Wax and EVA (ethylene vinyl acetate copolymer) or E
Those using A (ethylene acrylic copolymer) are known.

By the way, in normal pressure fixing, the recording medium is passed between a pair of steel rolls that are in pressure contact with each other, and in order to prevent offset, the surface of these rolls is 0.5 to n, as
Since it is polished to S*, the image after fixing is glossy and difficult to see. That is, it is difficult to obtain easy-to-see images with low gloss using ordinary magnetic toners, and it has been necessary to take measures such as roughening the surface of the fixing roll, for example.

SUMMARY OF THE INVENTION An object of the present invention is to provide a pressure fixing type magnetic toner which eliminates the above-mentioned drawbacks of the prior art, provides a glossy and easy-to-see image even when using an ordinary fixing roll, and has excellent fixing properties. It is.

The pressure fixing type magnetic toner of the present invention is a pressure fixing type magnetic toner mainly composed of magnetic powder and a resin that can be plastically deformed at room temperature, and its special enemy is the use of amide wax and ethylene ethyl acrylate as the resin.

The present invention will be explained in detail below.

In pressure fixing type magnetic toners, polyethylene wax is often used as the fixing resin in order to meet the required properties such as fixability, storage stability, and fluidity. Generally, polyethylene wax has strong adhesion against frictional forces such as scratches, but has weak adhesion to paper, etc., so EVA is added to polyethylene wax to improve its adhesion to paper. However, although this combination of polyethylene wax and EVA satisfies the above characteristics, the image after fixing has gloss.

Therefore, as a result of various studies, the present inventor used amide wax as the wax, and also used ethylene ethyl acryl).
By using a mixed resin containing (BEA) as the main resin component, it was possible to obtain an image that satisfied the above-mentioned characteristics and had significantly reduced gloss. First, the use of IJA can reduce the gloss of the image. The reason is as follows. Since this IJA has elasticity, when it is fixed under normal pressure (linear pressure of about 10 to 25 kg), it undergoes elastic deformation after fixing and no longer adheres to the paper.
In addition, the fixing surface becomes uneven and reflects light diffusely, resulting in a matte finish. Therefore, by mixing amide wax with EEA, the adhesion to K paper is improved.Moreover, since amide wax has good compatibility with EEA, satisfactory results can be obtained in terms of fixing performance.

The amount of IIJA and amide wax mentioned above is selected based on gloss and fixing properties, but in the CPC method, the ratio of BE/amide wax is 4/6 to 8/8 by weight.
It should be within the range of 2. In addition, in PPC, if the amount of amide wax is large, the toner will adhere firmly to the surface of the photoreceptor, reducing cleaning performance and forming a thin layer of toner, which is called a filming phenomenon. The range is preferably 2/8 to 6/4.

In addition to the above, other resins such as polypropylene and silicone varnish may be used as the resin component in the present invention. For example, printing durability is improved by adding 15 to 25 parts by weight of polypropylene to 100 parts by weight of resin.
Also, by adding 0.1 to 2.0 parts by weight of silicone varnish, offset properties are improved.

In magnetic toner, in order to obtain predetermined magnetic properties, 100 parts by weight of toner usually contains about 20 to 80 parts by weight of magnetic powder, but in the present invention, the content of magnetic powder is 25 to 80 parts by weight. It is preferable to set it as the range of 55 overlapping parts. This is because if the content of the magnetic powder exceeds 55 parts by weight, the fixing properties will deteriorate, while if it is less than 25 parts by weight, the magnetic properties will deteriorate, resulting in poor conveyance during blocking.

The magnetic powders include magnetite, ferrite), Hi
%Cr and other metal powders are known, but magnetite is preferred from the viewpoint of magnetic properties. Also, the magnetic properties of normal magnetic toner include IHc (coercive force) of 100 to 40.
005. Os (saturation magnetization) is 50 to 70 emn
/gr is considered to be good and can be adjusted according to the type and content of the magnetic powder.

Furthermore, in the present invention, as other components of the resin and magnetic powder, 8
Of course, fluidity modifiers such as i02, resistance modifiers such as carbon black, and various dyes and paper stocks as shown in Japanese Patent Application No. 175297/1984 may also be used.

The magnetic toner of the present invention can be prepared by known methods such as spray drying and pulverization, examples of which are as follows. First, raw materials such as resin and magnetic powder are premixed using a mixer or the like, then heated and kneaded using a kneader or the like, and then cooled and solidified.

Next, the cooled and solidified product is pulverized using a jet mill or the like, then subjected to a spheroidizing heat treatment, and then classified.

When developing with magnetic toner, the volume resistivity and particle size distribution of the toner are important. First, regarding volume resistance,
Since the CPC method does not require transcription, 102~
A low resistance of about 1010- is sufficient, but in the PPC method, it is 10! from the point of view of transferability. Ω, 1 or more is required, especially when using completely plain paper as a transfer sheet.
0″Ω.

- or more is preferable. Next, in the case of the CPC method, the particle size distribution is preferably about 5 to 40 .mu.m, but in the case of the PPC method, it is necessary to have a narrow particle size distribution of 10 to 20 .mu.m or 10 to 25 .mu.m due to the resolution and sharpness of the image.

〔Example〕

Amide wax (Bisamide Nippon Kasei) and ERA (DPDJ-6169, Nippon Konica) were used as resins.
0 parts by weight was used, and Fem0a (Toda Kogyo E) was used as the magnetic powder.
Using 50 parts by weight of PT500, these were mixed uniformly, mixed in a kneader at about 150°C, and then cooled and solidified. The cooled solidified product was coarsely pulverized and then finely pulverized to an average particle size of 20 μm using a jet mill. Then, to the crushed powder [1,
After adding 1 wt% of carbon black (Mitsubishi Kasei #44) and introducing it into a hot air stream at 130 to 160 °C,
It was classified into 0 to 20 μm. In this case, amide wax and E
Three types (A to C) of toners were prepared by changing the EA blending ratio.

In addition, in the above, only the resin is replaced with polyethylene wax (
Toner CD) was prepared by mixing HIWAX 400 P (manufactured by Mikata Petrochemical) and ethylene-vinyl acetate copolymer (Evaflex 450, manufactured by Mikata Polychemical) in a ratio of 7=3 (weight ratio).

A copy test was conducted using the above toners CA- and D), and the results shown in Table 1 were obtained.

The copy test was conducted using a commercially available transfer type copying machine (Se photoconductor, peripheral speed 100 m/sec, 1 surface potential + 750 V1).
Stainless steel sleeve outer diameter 52mmj+, outer diameter 29m
The test was carried out using a permanent magnet roll of 1-pole symmetrical magnetization with a diameter of 550 G on the sleeve. The development gap is 0.4.
mm1 Doctor gap 0.4mm.

The sleeve was rotated at 20 or more pom.

Further, fixing was carried out using two steel rolls (surface roughness 0.15) whose surfaces were plated with chrome at a linear pressure of 25 kg/cm.

Table 1 As is clear from Table 1, the toner of the present invention (A-C)
can significantly reduce gloss compared to conventional toners.・

Claims (1)

[Claims] t. A pressure fixing magnetic toner whose main components are a resin that can be plastically deformed at room temperature and magnetic powder, and which uses amide wax and ethylene ethyl acrylate as its main resin components.