JPH04174861A - Pressure fixing toner and its manufacture - Google Patents

Abstract

PURPOSE:To obtain capsule toner where polybutadienes are fixed onto the surface of core material by covering the core material containing pressure fixing components with shell material composed of polybutadienes. CONSTITUTION:When moderately elastic shell material such as polybutadiens is used under comparatively low pressure to which toner in a developing machine is subjected, toner will never be destroyed because of elasticity of polybutadiens even if the shell of capsule toner is deformed. Thus, as the shell of capsule toner, polybutadienes are used, and as a fixing component, for example, amido compounds are used. This thereby prevents the occurrence of blocking and caking, and also prevents toner from being filmed onto the developing machine, carriers and sensitive drum, thereby proving fixing toner high in properties.

Description

[Detailed Description of the Invention] [Summary] Regarding a pressure fixing toner used in electrophotography, the present invention provides a pressure fixing toner that has excellent blocking resistance, caking resistance, and filming resistance, and has high fixing properties, and a method for producing the same. For this purpose, a core material containing a pressure fixing component is coated with a shell material containing polybutadiene as a component.

[Industrial Application Field] The present invention relates to a pressure fixing toner used in electrophotography.

As an electrophotographic method, the method described in US Pat. No. 2,297,691 and the like is well known. This generally involves using a photoconductive insulator (such as a photocondrum), applying a -like electrostatic charge on the photoconductive insulator by corona discharge, etc. An electrostatic latent image is formed by irradiating a light image, and then the latent image is developed and visualized using a fine powder called toner. After transferring the toner image to paper etc. as necessary, pressurization and heating are performed. ,solvent.

A toner image is melted using steam, light, etc. and fixed on paper, etc., to obtain a printed matter. Toners for developing these electrostatic latent images have conventionally been made by dispersing coloring agents such as dyes and carbon black in a binder resin made of natural or synthetic polymeric substances, which is finely pulverized to about 1 to 30 μm. particles are used.

[Prior Art] Such toner is usually used alone or mixed with a carrier material such as iron powder or glass beads to develop an electrostatic latent image.

When toner is used alone for development (-component development method)
, toner usually contains magnetic powder, and the toner is frictionally charged by friction with the walls of the developing device and members in the developing device such as blades and magnet rolls, and furthermore, due to the magnetic force of the magnet roll, The toner is held on a magnetic roll, and as the magnetic roll rotates, the toner is transported to the latent image area on the photoconductive insulator, and only the charged toner adheres to the latent image due to electrical attraction, resulting in development. be exposed. In addition, when using a mixture of carrier and toner (two-component development method), the developer consisting of toner and carrier is mixed and stirred in the developing device and is triboelectrically charged, and the toner is supported on the carrier. Development occurs when only the charged toner that is transported to the latent image area on the photoconductive insulator selectively adheres to the latent image due to electrical attraction. In this case, iron powder or other ferromagnetic particles are often used as the carrier, and in this case, the magnetic particles are held by a magnet roll in the developing device to form a magnetic brush, and the magnet roll rotates. The toner is transported to the latent image area by bringing the magnetic brush to the latent image area on the photoconductive insulator.

Examples of such toner fixing methods include a pressure fixing method in which the toner is plastically deformed by applying pressure, a heated roll fixing method and an oven fixing method in which the toner is fixed by applying heat to the toner, and a toner fixing method in which the toner is fixed using an organic solvent. There are two methods, such as the solvent fixing method, which fixes the toner by melting it, and the optical fixing method, which fixes the toner by irradiating it with light and melting the toner with the energy, but the simplest method is to fix the toner by applying pressure. It is a pressure fixing method. That is, the present fixing method is suitable for downsizing and simplifying the apparatus because 1. no energy source is required for fixing.

2. A quick start is possible because there is no warm-up time required with other fixing methods such as a hot roll fixing method.

3. Since no additional heat or light energy is required during fixing, the power consumption of the apparatus can be kept low.

4. No thermal energy is required for fixing, so
It is highly safe and there is no need to worry about bad odors that are a problem with solvent fixing methods.

It is a fixing method that has attracted much attention in recent years as a fixing force for small-sized copying machines and small-sized printers for personal use.

The binder resin used for pressure fixing needs to be firmly fixed on the recording medium such as paper by only applying pressure, so it is necessary to use a soft resin that easily undergoes plastic deformation when subjected to pressure, such as low molecular weight polyethylene wax. It is said that it is desirable to use polypropylene wax, amide compounds, etc.

[Problems to be Solved by the Invention] However, in such conventional toners, when the above-mentioned soft resin is used alone, the following problems occur.

1. During toner storage or in the toner replenishment hopper in the device, toner particles adhere to each other due to slight pressure or heat, causing agglomeration phenomena such as blocking and caking. When this phenomenon occurs, the toner from the toner hopper cannot be reinforced smoothly.

2. Blocking and caking occur, causing the particles to aggregate with each other, making it impossible to appropriately triboelectrically charge the toner due to changes in the particle size and shape of the toner.

3. Because the binder resin is soft, the toner adheres (filming) to the parts where the toner is triboelectrically charged, such as the blade in the -component development method, the carrier, etc. in the two-component development method, and is not suitable for the toner. Frictional charging becomes impossible.

4. The resins commonly used in pressure fixing toner binders, such as the exemplified polyethylene, polypropylene, and amide compounds, can be used even when a charging aid such as a dye is added.
It has a characteristic that it is difficult to be triboelectrically charged, and it becomes impossible to maintain the amount of charge required for development due to slight fluctuations in usage environmental conditions or development process conditions.

5. Filming of toner on the photocondrum may impair the optical and electrical characteristics of the photocondrum, making it impossible to form an appropriate latent image.

The present invention has been made in view of such conventional problems, and provides a pressure fixing toner having excellent anti-blocking, anti-caking and anti-filming properties and high fixing properties, and a method for producing the same. It is an object.

[Means for Solving the Problems] In a capsule toner for pressure fixing, the shell material is required to have appropriate hardness. This is to prevent the shell from being destroyed by the pressure applied when the toner is stirred in the developing device.

When the shell of the capsule toner is destroyed in the developing device, the toner adheres to the photosensitive drum and carrier, which hinders the formation of latent images on the photosensitive drum.This causes a decrease in the charging ability of the toner, resulting in a decrease in print quality. This may cause problems such as On the other hand, if the shell material is too hard, it becomes necessary to increase the fixing pressure accordingly. If the fixing pressure is too high, the device will inevitably have to be larger in order to withstand the pressure, and further problems will occur, such as rolling of the printing paper and excessive gloss on the printed surface.

In consideration of the above-mentioned circumstances, the present invention covers a core material containing a pressure fixing component with a shell material containing polybutadiene as a component.

Further, in the present invention, the polybutadiene is dissolved in methyl ethyl ketone, the solution is sprayed around the core substance by a spray drying method, and the solvent is removed in high-temperature air to perform encapsulation. .

The present invention will be explained in more detail below.

If a shell material with moderate elasticity such as polybutadiene is used, the shell of the capsule toner will deform due to the elasticity of polybutadiene and the toner will be destroyed under relatively low pressure applied to the toner in the developing device. It doesn't reach that point. On the other hand, when a large instantaneous pressure is applied, such as the pressure applied by a fixing roller, the polybutadiene shell is destroyed, and the fixing component, which is the core substance, is released and fixed.

In this way, by using polybutadiene in the shell of the capsule toner, for example, an amide compound is used as the fixing component. It is possible to obtain a pressure fixing toner that does not cause blocking or caking, and does not cause filming of the toner in the developing device, on the carrier, or on the photosensitive drum, and has high fixability. Further, polybutadiene is dissolved in MEK, the solution is sprayed around the core material by a spray drying method, the solvent is removed in high temperature air, and encapsulation is performed. This allows polybutadiene to be fixed on the surface of the core material.

[Examples] Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto.

As a binder resin for toner, CH3-CH(OH)-
(CH2N2-CONH-C6H6-NHCO-(CH
An amide compound having a structure of 2N2-CH(OH)-CH3 and 5 parts by weight of carbon black as a colorant were added and melt-kneaded, and then jet-pulverized to about 5 to 15 μm to obtain a core material.

Then, 1,4-cis polybutadiene (CBR-M) was dried using a spray dryer model G5-31 (manufactured by Yamato Scientific).
A solution of nigrosine dye dissolved in MEK (Japan Synthetic Rubber Tree Co., Ltd.) was sprayed together with the core material into high-temperature air and the solvent was removed to fix polybutadiene on the surface of the core material to obtain a capsule toner. In addition, the film thickness of the capsule was 0.2 to 0.5 μm.

Using this capsule toner, toner thickness 1 is possible with a small printer.
A powder image of 5 to 30 μm is formed on a recording paper, and the powder image is placed under a linear pressure of 20 kg/an and a nip length of 0. Pressure fixing was performed through a 6 mm pressure fixing section to obtain a fixed image.

Adhesive tape (Scotch adhesive tape; Resident 3M) was attached to this fixed image with a constant load (1 kg), and then peeled off at a peeling angle of 45 degrees and a peeling speed of 2.5 an/s.
The optical print density of the image before and after peeling off the tape was measured, and the fixability was evaluated based on the ratio of the optical print densities.

Regarding blocking and caking characteristics, we filled a Petri dish with toner and applied a load of 100 g/aIr.
Leave it in an environment with a temperature of 50°C and a humidity of 35% RH for 12 hours.
The degree of blocking occurring under these conditions was evaluated by visual judgment.

As a result, the retention rate was over 80%, and blocking,
No caking occurred.

Moreover, no toner filming was observed on the photosensitive drum of the printer and the fixing pressure roller after printing a large number of sheets.

[Effects of the Invention] As described above, according to the present invention, by using a spray drying method, it is possible to manufacture a capsule toner in which polybutadiene is fixed on the surface of a core material.

In addition, by using polybutadiene as the shell material of the pressure fixing toner, it is difficult to cause blocking or caking, and the toner does not film on the photosensitive drum or fixing pressure roller, and has high fixing properties. You can get toner.

Claims (2)

[Claims] (1) A toner for pressure fixing, characterized in that a core material containing a pressure fixing component is coated with a shell material containing polybutadiene as a component. (2) A toner for pressure fixing characterized in that the polybutadiene is dissolved in methyl ethyl ketone, the solution is sprayed around the core material by a spray drying method, and encapsulation is performed by removing the solvent in high-temperature air. manufacturing method.