JPS5836770B2 - Electrostatic latent image developing method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrostatic latent wet development method and apparatus using a developer containing a magnetic material.

Conventionally, a method for developing an electrostatic latent image using a liquid developer has generally been carried out by impregnating an electrostatic latent image holder, such as a zinc oxide photosensitive paper, in a developer.

However, this method has disadvantages in that a large amount of developer adheres to the electrostatic latent holder, resulting in a lot of background smearing and an excessive burden on drying.

Among these drawbacks, a method of pre-wetting with a carrier liquid or a diluted developer before the impregnation process has been proposed as a means to prevent background smearing.

However, this pre-wet method has the disadvantage that the apparatus becomes complicated and large due to the addition of one step.

In addition, roller development methods have been proposed as a means to reduce the amount of developing solution attached, but the amount of pumping up is limited or insufficient, resulting in low image density with developing solution of normal concentration.
Additionally, using a thick developer to increase the density of the image resulted in increased background smearing.

On the other hand, Special Publication No. 40-6037 and Special Publication No. 49-46
No. 265 proposes a method in which the electrostatic latent image holder is immersed in a developer containing a magnetic material for development, but this method also causes more carrier liquid to adhere than necessary, and as mentioned above, The shortcomings regarding drying cannot be overcome.

An object of the present invention is to provide a method and apparatus for developing an electrostatic latent image that eliminates all of the above-mentioned drawbacks by using a self-fixing developer containing a magnetic material and a sleeve with a built-in magnet for holding the same.

Another object of the present invention is to provide a method and apparatus for developing an electrostatic latent image in which a large amount of developer is not deposited and, therefore, the burden of drying is reduced.

A further object of the present invention is to provide an electrostatic electrostatic system that can provide a pre-wetting effect and perform a dewetting process in one step, thereby avoiding the complexity and size of the device, and obtaining high-contrast images with less background smudge. A method and apparatus for developing a latent image are provided.

That is, the developing method of the present invention is an electrostatic latent image developing method in which an electrostatic latent image carrier is developed with a self-fixing liquid developer containing a magnetic material, in which a certain amount of the developer is applied to the surface of a sleeve containing a magnet. The liquid surface is brought into contact with the electrostatic latent image surface of the holder.

A developing device for carrying out such a method includes a sleeve having a built-in magnet, a pressure roller disposed in pressure contact with the sleeve, and means for supplying a self-fixing liquid developer containing a magnetic material to the surface of the sleeve. It is a combination of

The method of the present invention will be explained below with reference to the drawings. Fig. 1 is a diagram of an example of an apparatus in which a developing tank is used as a developing solution supply means, and Fig. 2 is a diagram showing an example of an apparatus in which a developing tank and a developer application roller are used as a developing solution supply means. FIG. 3 is a modified view of the device shown in FIG. 2, FIGS. 4 and 5 are examples of sleeves with built-in magnets, and FIG. 6 is a developer liquid level on the sleeve. FIG.

In FIG. 1, as a developer supplying means, for example, a magnetic material-containing self-fixing developer 2 in a developer tank 1 is drawn up by the rotation of a sleeve 3 with a built-in magnet and is deposited on the sleeve surface.

The amount of liquid can be adjusted, if necessary, by a squeeze roller 4, which contacts the sleeve 3 and rotates at a different speed than the sleeve.

On the other hand, the electrostatic latent image holder 5 is connected to a pair of conveying rollers 6, 6'.
The sleeve 3 is inserted with the latent image surface facing downward between the sleeve 3 and a pressure roller 7 provided close to the sleeve 3 so as to be able to press against it.

The gap between the sleeve 3 and the pressure roller 7 is adjusted to such an extent that the latent image surface of the holder 5 comes into contact with the developer surface on the sleeve 3.

In this way, the latent image on the holder 5 inserted between the sleeve 3 and the pressure roller 7 comes into contact with the developer on the surface of the sleeve 3 and is developed.

The state of the developer on the sleeve 3 at this time is as shown in FIG.

That is, the magnetic substance-containing particles (toner) 2 in the developer are attracted by the magnet (not shown) in the sleeve 3 and are mostly present on the inner surface of the sleeve, while the carrier liquid 2' is present on the outer surface of the sleeve. Existing.

Therefore, the latent image on the holder 5 is first brought into contact with a carrier liquid or a dilute developer, and then brought into contact with a concentrated developer and developed.8 The obtained image is fixed by natural evaporation of the adhered carrier liquid. In order to fix the image more firmly, for example, the holder 5 may be passed between a pair of squeezing rollers 8 and 8l.

Further, the apparatuses shown in FIGS. 2 and 3 are examples in which the developer supply means to the sleeve 3 is performed by a combination of the developer tank 1 and the roller 9, but in the apparatus shown in FIG. Since the latent image surface of the holder 5 faces upward, it must be passed through.

On the other hand, in the apparatus shown in FIG. 3, the pressure roller 7 is provided on the sleeve 3 as in the case of FIG. 1, so that the latent image surface of the holder 5 faces downward.

Note that when the developer application roller 9 is provided as shown in FIGS. 2 and 3, the developer tank 1 becomes structurally smaller. Continuous operation is possible by providing a means for supplying and draining the developer using a pump.

As described above, in the developing method of the present invention, a pre-wet effect or an effect similar thereto is imparted and development processing is performed in one step.

It has been found that development with this N is performed primarily by electrostatic attraction between the latent image charge and the charged toner particles.

That is, it has been found that the developing method of the present invention is of a type essentially different from the conventional dry developing method in which development is performed using magnetic powder.

As described above, since the present invention has a pre-wetting effect, a clear image with less background staining can be obtained.

In the present invention, the appropriate amount of developer on the sleeve is approximately 0.1 to 2 mm and 8 degrees in terms of liquid film thickness.

The amount of liquid can be easily adjusted by controlling the shape and number of magnets, the strength of magnetic force, the number of rotations of the squeeze roller, the distance between the sleeve and the latent image holder, and the like.

The magnets used here are exemplified as single-pole rectangular and eight-pole roller types as shown in Figures 4 and 5, but the present invention is not particularly limited to the number of poles or the shape. do not have.

However, in general, the larger the number of poles, the more the amount of developer on the sleeve surface (
This is preferable because the liquid film thickness) becomes uniform.

The developing method of the present invention can be applied to latent image carriers that can directly form recorded images, such as the above-mentioned ZNO paper, as well as drum-type photosensitive materials such as SE or organic photoconductors. It also includes the body.

In the latter case, it is necessary to transfer the toner image developed by the above method onto plain paper or the like.

The liquid developer used in the present invention is a self-adhesive one containing a magnetic material, and contains a magnetic material such as iron powder or γ-ferrite, a pigment if necessary, and a dissolving agent used in a normal dry developer. Resins with a parameter of 8.5 or more [e.g. styrene resin, acrylic or methacrylic resin with C3 or less, styrene ~
Butadiene (styrene/butadiene≧8/2), maleic acid resin, butyral resin, phenol resin, polyethylene, etc.] is crushed and classified to collect fine particles of 10μ or less, preferably 5μ or less, and these are used in a normal liquid developer. Add self-fixing resins with a solubility parameter of 8.5 or less (e.g., styrene to bucdiene resin (styrene/bucdiene <8/2), C4 or higher acrylic or methacrylic resin, low molecular weight polyethylene, etc.) used in Accordingly, conventional additives such as polar agents and dispersants are added and kneaded in a small amount of carrier liquid such as petroleum hydrocarbon to form a concentrated toner, which is then diluted with the carrier liquid.

In addition, resins for dry developers have a ratio of 0.1 to 0.1 to the magnetic weight.
It is used in an amount of 10 times, preferably 0.5 to 2 times, and the resin for liquid developer is used in an amount of 0.5 to 10 times, preferably 1 to 5 times, the weight of the magnetic material.

The toner particles thus obtained have a structure in which a magnetic material is sequentially coated with a hard resin layer and a self-fixing resin layer.

Examples are shown below.

Example 1 100 parts of γ-ferrite (weight, same hereinafter) and 100 parts of styrene resin were kneaded in a three-roll mill, pulverized and classified to separate particles with a particle size of 1 to 10μ, and treated as follows to produce A fixable liquid developer was prepared.

The above magnetic powder 10 parts Acrylic resin (lauryl methacrylate - dimethylaminoethyl methacrylate 20 parts copolymer, molecular weight: 10,000 to 50,000) Nickel naphthenate 0.05 part Petroleum hydrocarbon 70 parts (Esso Chemical A concentrated toner was obtained by dispersing Isopar H) in a ball mill for 24 hours, and 2(l) was dispersed in Isopar H17 to obtain a developer.

Next, pour this developer into the developing tank of the apparatus shown in Figure 1 until the thickness of the liquid film on the sleeve surface is approximately 0. The rotational speed of the sleeve (having an 8-pole magnet with a surface magnetic force of 700 gauss) and the squeeze roller was adjusted so that the electrostatic latent image was formed on the electrostatic latent image holder made of ZNO photosensitive paper. When the paper was fed at a speed of 80/sec, an image density of 0.98 and background density of 0.10 with good contrast was obtained.

Comparative Example 1 When the same method as in Example 1 was repeated except that a sleeve without the magnet was used (the developer was also the same), an extremely poor image was obtained with an image density of 0.28 and a background density of 0.10.

Example 2 The same method as in Example 1 was repeated except that a developer prepared by dispersing 100 g of the same concentrated toner as in Example 1 in 14 Isopar H was used, and the image density was 1.12 and the background density was 0. A high contrast image of .14 was produced.

Comparative Example 2 When the same method as in Example 2 was carried out using a device using a sleeve without the magnet, the image density was 0.71,
An unclear image with a background density of 0.45 and a lot of fog was obtained.

Example 3 When the same developer as in Example 1 was applied to the apparatus shown in Figure 2 (sleeves etc. are the same as the apparatus shown in Figure 1), the image density was 0.9.
3. Clear image quality with a background density of 0.10 was obtained.

Comparative Example 3 When development was carried out using the apparatus having the sleeve without the magnet in Example 3, only an extremely poor image with an image density of 0.23 and a background density of 0.10 was obtained.

Example 4 The same method as in Example 3 was repeated except that the same developer as in Example 2 was used, and the image density was 1.02 and the background density was 0.1.
Two high contrast images were created.

Comparative Example 4 When the same method as in Example 4 was repeated using the device having the sleeve without the magnet, the image density was 0.
65, a blurred image with a background density of 0.38 and a lot of fog was formed.

[Brief explanation of drawings]

Figures 1 to 3 are device diagrams of an example of the present invention, and Figures 4 to 5 are
FIG. 6 is a cross-sectional view of an example of a sleeve with a built-in magnet used in the apparatus shown in FIGS.

Claims (1)

[Scope of Claims] 1. An electrostatic latent image developing method in which an electrostatic latent image holder is developed with a self-fixing liquid developer containing a magnetic material, wherein the developer is uniformly applied to the surface of a sleeve containing a magnet. 1. A method for developing an electrostatic latent image, which comprises: holding a liquid in an amount of the electrostatic latent image, and bringing the liquid surface into contact with the electrostatic latent image on the holder. 2. An electrostatic latent image developing device that combines a sleeve with a built-in magnet, a pressure roller provided so as to be able to come into pressure contact with the sleeve, and means for supplying a self-fixing liquid developer containing a magnetic material to the surface of the sleeve. .