JPS5840741B2 - Electrophotographic contact exposure method - Google Patents

Description

[Detailed Description of the Invention] The demand for secondary original drawings such as general survey topographic maps, precision mechanical design drawings, basic shipbuilding design drawings, architectural civil engineering drawings, etc. is increasing in order to streamline drafting.

The methods include silver halide photography, photosensitive resin photography,
Diazo method etc. are widely used.

However, since silver halide photography and photosensitive resin photography involve wet development, the base film expands and contracts during development and lacks dimensional stability. Due to changes in humidity, the dimensions further changed after duplication, and quality during long-term storage remained a problem, and the compilation of the map,
This causes inconvenience in register mark alignment when printing in multiple colors.

In addition, the diazo method causes similar problems such as discoloration and fading of the base during storage and dimensional stability, and the quality is still unsatisfactory.

The present inventors have found a new method for improving the drawbacks of the second original and obtaining highly accurate second original drawings using an electrophotographic method.

The electrophotographic method can electrostatically transfer an image from a master paper to paper, polyester film, synthetic paper, etc. and form the image on the base of your choice. If you use
It is possible to obtain products with much higher precision in terms of storage stability, dimensional stability, discoloration resistance, etc. than conventional methods.

In this method, only the image is transferred onto the base, so the base does not change color or fade, making it an ideal second original for long-term storage.

There are two methods of electrophotography: camera-based exposure, which exposes light through a lens, and contact exposure. However, exposure through a lens has problems with blurred images and reduced dimensional accuracy due to lens aberrations and the color of the original.

According to the contact exposure method, a second original map or a transparent original is used to closely expose the original to make a direct copy, so the reproduced product is faithful to the original map, and is widely used for calculating the area of maps and has high accuracy. It is highly praised for its quality.

However, in the case of contact exposure, when copying from a transparent original using the contact exposure method, if the transparent original is placed directly on a charged master paper and brought into close contact with it in a vacuum, static electricity is generated during the process of peeling off the original. Development causes complicated problems such as image distortion and image disappearance.

This phenomenon is caused by the interaction between the static electricity on the charged master paper and the static electricity accumulated on the surface of the original that is in close contact with it, as well as the accumulation of static electricity on the surface of the original when a high-resistance film original is used. The interaction between the electrostatic voltage and the charged voltage on the mask-paper causes discharge and sparking, creating a lightning bolt-like mark and erasing the image in this area.

In addition, when tracing a transparent document using drafting ink, etc., the image is made of ink containing hydrophilic gelatin, etc., and has a low surface resistivity, so the image may be affected by changes in atmospheric humidity. When the surface resistivity of the master paper further decreases and the charged master paper is exposed in close contact with the original, the electrostatic latent image on the master paper moves and disappears, so even if developed, all or part of the image remains The result is that the image disappears or is only vaguely expressed.

Therefore, such development cannot be avoided even if the humidity of the document is adjusted to the optimum humidity of about 60 to 80% by air conditioning and contact exposure is performed.

The present inventors inserted a transparent plastic sheet or film, coated with a conductive resin on one side to lower the surface resistance, between the master paper and the original so that the conductive resin layer was in contact with the original, and then exposed the film to the original. We found that this difficulty could be solved by doing the following.

More specifically, a master paper is placed on a metal substrate, and a charger (corotron) applies a voltage of 6 to 10 V to the surface of the metal substrate to create an electrostatic potential on the master paper, and then plastic is placed on top of the master paper. Spread a film, preferably a polyester film, coated with a layer of conductive resin on one side (hereinafter referred to as low-resistance film) with the coated side facing up. Next, place the original with the image facing down so that it is in contact with the conductive resin layer. Place a glass or plastic film cover over the entire surface, evacuate the entire surface using a vacuum pump through the hole provided in the metal substrate, bring the original drawing, low resistance film master paper, and cover film into close contact with the metal substrate, and place a light source on the surface. Next, open the eyelids under vacuum, remove the cover film, peel off the master paper and the inserted low-resistance film, and develop the master paper using a positive developer using a brushing method according to a prescribed method, resulting in image disturbance. A clear, high-density image with good resolution and no blemishes was obtained, and no problems occurred during peeling.

This developed master paper is transferred to the matte surface of dimensionally stable polyester for transfer using a predetermined method and fixed.
For example, by fixing with solvent vapor, a product with a clear image, excellent dimensional stability, and high precision that is ideal for a second original image can be obtained.

Although it is not clear why the above-mentioned effects can be obtained by inserting a low-resistance film having a conductive resin layer between the original and the master film in the present invention, it is clear that the film is made of a film with high surface resistance. When a manuscript is used, the charge accumulated on the surface resistance film surface due to the action of the charge accumulated on the master film is electrically neutralized by the conductive resin layer of the low resistance film inserted in the middle. It is thought that this is because the surface charge on the document decreases.

On the other hand, when using an original made of a film with low surface resistance, the charge accumulated on the master paper can be prevented from escaping to the low resistance film original by inserting a low resistance film which is an insulator inserted in the middle. It is thought that this is due to the fact that he is forced to do so, but this alone cannot explain everything.

As the conductive resin applied to the low resistance film inserted in the middle, commercially available conductive resins are sufficiently effective.

However, the conductive resin layer is not effective if its surface resistance is too high or too low, and the surface resistance of the resin layer is 1X10'' to 1×107 under standard conditions (20°C, humidity 60%).
It is preferable to use it as follows.

In other words, if the surface resistance is I x 10'' or more, the surface resistance is too high and the surface charge of the original cannot be neutralized sufficiently, and if the surface resistance is I x 107 or less, the surface resistance is too low. It is thought that this is because the movement of the surface charge of the original is not sufficiently blocked and the effect cannot be expected.

In the above, the surface resistance value of the low-resistance film was shown as the measured value in the standard state, but since the production of the second original drawing is often carried out in the standard state, the measured value in the standard state was shown. Even when using a low-resistance film under other circumstances, good results can be obtained using a low-resistance film having a surface resistance within this range under the circumstances.

Although the surface resistivity of the conductive resin layer changes somewhat depending on its coating thickness, in the present application, it is generally convenient to use one coated to a coating thickness of about 2 to 5 μm.

However, if two or more layers are coated, the light-shielding properties will increase, which is not preferable.

In the above, only polyester film was exemplified as a low-resistance film for intermediate insertion, but any transparent plastic film can be used as it has excellent insulation properties, but specific examples include vinyl chloride film, Examples include polyethylene film, polyester film, vinylidene chloride film, nylon film, and polypropylene film.

Cellophane can also be used.

There are two types of conductive resins: those in which conductive fillers such as silver powder, silver oxide, and carbon black are added to resins to impart conductivity, and organic conductive polymer compounds such as polymer electrolytes.

Regarding the first type, various resins can be used as the base resin of the conductive resin, and from among these, one that has good adhesion to the plastic film used for the low-resistance film may be selected and used.

The conductive resin to be used should preferably be one that has good adhesive properties and does not cause cloudiness, stickiness, or cracking; it is especially convenient to use a water-soluble type or emulsion type.

Example 1 A conductive resin solution (20 parts of conductive resin, 80 parts of a 9:1 solvent of methyl ether, methyl ketone and methanol) was applied to a base film (HoIJ ester 25μ film) using a roll coke, dried, and coated. When the surface resistivity of a conductive resin layer with a thickness of 2 to 3 μm was measured, it was found that at 20°C relative humidity 6
At 5%, the following results were obtained.

※※The obtained film exhibited no cracking, cloudiness, or stickiness on the surface, and the adhesion of the conductive resin layer was good, indicating that it was in good condition as a low-resistance film.

A master paper was placed on an aluminum substrate in a dark room and charged with a voltage of 8 KV using a charger (corotron). Next, a low resistance film prepared by the above method was spread on top of it with the coated side facing up, and then various resins were applied. Place the original traced with drafting ink on a tracing film with the image facing down so that it is in contact with the coated surface of the low-resistance film, and place a transparent film over it using a transparent film to create a vacuum through the hole in the metal substrate. The film master paper and metal substrate are brought into close contact with each other and exposed using a 5W tungsten light source.

Next, the master paper and the low-resistance film were peeled off, and brushing development was performed using a processing method. As a result, a high-resolution, high-density image faithful to the original without image distortion was obtained.

This was transferred to a polyester matte film and fixed using a solvent vapor fixing machine to create a highly accurate second original image.

Using any of the films showing the surface resistivity values of the low resistance films obtained using various conductive resins as described above, it was possible to obtain second original images with excellent high precision.

(8) Polyester film The materials used as manuscripts include plastic films with high surface resistivity or papers with low surface resistivity, such as tracing paper, and the image formation used on these films has surface resistivity. There are printed materials that have a high surface resistance, or ink for villagers that have a low surface resistivity.
This combination produces four types of combinations, and in this width, generally speaking, from the above-mentioned contact electronic copying, tracing paper with a low surface resistivity is printed with a high surface resistivity. Copying can be performed without causing problems in the ratio, but if the number of copies is large, clearer images can be obtained by using the low resistance film of the present invention.

In other cases, for example, in the case of a high surface resistance film printed on a plastic film, both the base and the image have high surface resistance, so they come in contact with the master paper and discharge, creating a so-called lightning bolt mark and erasing the image in that area. It is often triggered to do something.

Furthermore, when plastic is inked or tracing paper is inked, the surface resistance of the image is low, so the image tends to run away, making it difficult to obtain a clear copy image on master paper.

In such cases, by inserting a low-resistance film between the original and the master paper according to the method of the present invention, it is possible to obtain a copy image that is still clear on the master paper even if many copies are made.

Comparative Example 1 When the surface resistivity of the inserted film is higher than IXl, 011, a master paper is placed on an aluminum substrate in a dark room and dark charged with a voltage of 8KV using a charger (corotron), and then a 25μ polyester film with high surface resistivity is Unfold the film, then insert the original image traced with drafting ink onto the tracing film, place it face down so that it touches the polyester surface, cover it with a transparent film, apply a vacuum through the hole in the metal substrate, and remove the original image. The high-resistance polyester film mass L-Haver was brought into close contact with the metal substrate and exposed to light using a 5W tungsten light source.Then, the master paper and high-resistance polyester film were peeled off and the master paper was developed by brushing according to the prescribed method. As a result, image disturbance and image disappearance (partially) occur.This development becomes especially noticeable when the humidity is lower than 60%.Also, if the inserted high-resistance polyester film is used repeatedly, the film will become triboelectrically charged, causing a complicated phenomenon and making it difficult to work. It's impossible.

Comparative Example 2 When the surface resistivity of the inserted film is lower than 107 Same as above, the surface resistivity of the inserted film is set at 20°C and humidity 60%.
When contact exposure and development was performed using a film coated with a low resistance resin lower than 107, the image formation was poor.

Claims (1)

[Claims] 1 In the electrophotographic contact exposure method, I
A low-resistance film with a surface resistivity of 011 to 1 x 107 is inserted with the conductive resin layer facing the original, exposed to light from above the original, developed by electrophotography, and transferred and fixed to the base surface. The above method is characterized in that: