Third, pre-coating plate (PS) plate method

 

Pre-coating plate or PS version, is the Pre - Sensitized plate to write. Refers to the coating on aluminum version of the photosensitive layer plate and then sold to the printing shop to use. It is with heavy nitrogen or azide, nitro sensitizer and the mixture of the resin emulsion, coating on the version of the base, after drying can deposit reserve, so called pre-coating plate.

 

When using the PS edition print, can save from plate grinding to baked version and a series of process, direct contact with negatives exposure, development and so on, has simple operation, high power business, the advantages of stable performance, good quality. Has been widely used abroad, domestic also have multiple production of PS version of the production line, usage is further expanded.

 

Pre-coating plate according to the sensitive principle and technology of the photosensitive layer, divided into Yang pattern PS version and Yin graphics PS version.

 

1. Yang pattern PS version

 

Said Yang pattern with P, the P type, it is to use Yang like bask version of the film. Yang pattern of sensitizer is using diazo see light after decomposition, and then was dissolved with a dilute alkali solution development, and aluminum version of the base, forming a plate blank parts, namely the graphic part, and did not see the light part of the photosensitive layer did not have any change, also not be dissolved by dilute alkali solution, still stay on the page, the oil-wet printing parts of the plate, can be directly printing ink.

 

In addition, also useful compounds into nitrogen alkenyl or by hydrogen transfer changes, such as solubility, in this kind of coating solution, such as linear phenolic resin polymer, made by solid foundation, and does not need to add lipophilicity for reinforcing the base paint. So this kind of plate is also known as type.

 

2. Yin graphics PS version

 

Yin pattern with N, N type, it is cloudy like film print. Yin pattern of sensitizer, general is the use of diazo see light after crosslinking or aggregation, become the substance does not dissolve in solution, and did not see the light of soluble in solution, therefore, exposure after development, remove not photosensitive layer, publishing base, a blank part of hydrophilicity, and see the light of insoluble matter has lipophilicity, become the graphic base, due to the partial abrasion resistance, resistance to seal strength is low, in order to improve the weakness, in strengthening the graphic on the coating paint, so this kind of plate called the appearance.

 

Pre-coating plate printing process for: ink on the exposure and development - stop show - - in addition to the dirty - baked version.

 

Precoating method and flat gravure exposure is the same version of exposure, plate burning light available with a near ultraviolet range of light.

 

Enhancement available manual development, also can use PS version developing machine for development. Manual enhancement with long wool brush. Pour developer in uniform layout brush, and constantly changing fresh liquid, use PS version developing machine is developed, the sun good plate off into the machine, plate automatically advance, mobile while automatic spray for development, and then rinse with water, dry plate output machine.

 

Part or dirty pages don't need points, available in addition to the dirty fluid to remove it, when available small brush brush besmear with solution on the layout, and then rinse clean with water.

 

Pre-coating plate of photosensitive layer itself has color, show obvious on the aluminum version, generally without inking, can direct printing, if don't print immediately, will be stored, indoor light is too strong, the plate on the graphic part will be light, so also need to go to the ink, the ink method can use the circle of the ink, ink roller roller ink method is also available.

 

Baked version purpose is to improve the plate resistance force, general precoating version of the resistance force about 100000 printing, such as after 230 ℃ temperature bake for about 10 minutes, plate printing endurance can improve 4 ~ 5 times. Baked version of PS version of baked version of the dedicated machine.

 

Four, namely coated plate plate making method

 

Xu plate (wiper - on plate) refers to the printing shop using diazo photosensitive liquid coating on its own, is now in lithographic plate. Coated plate is in the use of diazo resin pre-coating plate at the same time, considering the save money and the regeneration of plate material is used, the for pre-coating plate using diazo resin light-sensitive materials, as by the users themselves to coating method and developed.

 

The coated plate using diazo resin photographic materials, the same as the precoating material used in the plate, there are Yang pattern and Yin pattern.

 

Namely coated plate photosensitive liquid coating, the simplest way is in the layout of casting coating solution, brush divide evenly with rubber sponge brush, extensive use, also can use special roller coating the wind coated, but generally does not use the centrifugal coating baking edition machine, can be used after coating is dry. Coating can be stored on the aluminum plate for several months with no dark reaction. Coating on the zinc plate for about 12 hours of dark reaction.

 

The sensitive version of the plate making process, namely basically similar with the PS version, as follows: plate grinding to pretreatment to the sensitive liquid, dry, exposure and development process to TuJi paint, glue, dry.

 

Namely the advantages of the coated plate, in addition to the cost is lower than the PS version, there are the following: it is a kind of the coated plate, surface treatment of aluminum plate can be controlled, and the abrasive grain and anodic oxidation treatment method can be arbitrary choice. Can, therefore, production to meet the requirements of printing quality and resistance force printing plate, generally between 2 and 100000 printing, also can use the PS version of regeneration, used as proofing plate.

 

Five, the other lithographic plate method

 

1. Dry lithography

 

Lithography is usually based on the principle of oil and water don't mix, plate making and printing. To wetting water when printed pages blank part of the adsorption ink, not make them but after this section water, caused by the factor of water print colour and lustre is reduced, paper expansion influence overprint.

 

Dry offset is not water wetting layout for lithographic way, or no horizontal version, used the method of letterpress plate making, made layout by higher than blank parts from 25 to 30 microns. When printing with embossed promising.it, no layout of the water, called dry offset printing. Now, in the blank of backwash ink material is formed on aluminum parts, for printing.

 

Around 1970, study with the property of the silicone backwash ink plate making, constitutes a research report on the ink stripping mechanism at the same time, the development of the following is a representative example.

 

(1) 3 m way

 

American 3 m company invented the dry offset, diazo photosensitive layer coated on aluminum plate, and then coated silicone rubber layer on the PS version, contact exposure from Yin as negative, and economic development, graphic part by light, diazo photosensitive layer is broken down, with a silicone rubber layer is removed to dissolve and bared metal aluminum, the ink on graphic part of the aluminum, the blank portion of the silicone rubber ink adhesion, so can perform a waterless printing.

 

(2) the way of toray

 

Japan toray company no horizontal version of the production process. Built on the aluminum plate photopolymerization type photosensitive layer, as on the coated silicon rubber, the final composite protective film. Contact with the protective film from Yang as negative contact exposure, stripping protective film, developing solvent, the blank part by light, the photoreceptor layer and the silicon as the surface of the rubber forming strong backwash ink layer, graphic part is not light, silicone rubber layer with photosensitive layer was removed, bared metal aluminum and can be attached ink printing part.

 

(3) with the method of photosensitive silicon

The way is giving silicone to photosensitive, making light sclerosis type photosensitive layer, and Yang like film contact exposure, make blank part form over-dials the performance of the ink. The photosensitive material by organic siloxane and aromatic double fold the mixture of ammonia compounds, or use the side key introduction of azide group method.

 

And synthetic photopolymerization type photosensitive silicon, the coating on the aluminum plate, made into stripping enhancement of silicon in type lithography. This is mainly used in printing field.