Analysis of Factors Affecting Printability of CTP Plates in Printing Process

Printing rate of printing plates usually refers to printing plates from the beginning of printing to the failure of printing plates.

The number of brush transfers, the form of printing plate failure usually includes wear of the photosensitive layer of the printing plate

, printing blank wear failure and printing plate base failure three situations. Printing production

The factors affecting the printing rate of CTP media in Cheng Zhong are various and summarized mainly

And the two major aspects of platemaking and printing, this article will start from these two aspects to analyze the impact version.

The factors of the durability of the material, hope to provide you with benefits in the production of such problems

Ideas and solutions.

I. CTP plate making

1. If the light path of the CTP platesetter is not clean for a long time or the focus is not correct

It will cause the laser energy output on the surface of the plate to be lower than the plate to produce photopolymerization reaction.

With the required laser energy value, the photosensitive layer on the surface of the plate cannot be completely processed.

Photopolymerization of photochemical reaction, so that the photosensitive layer in the graphic part cannot be completely cross-linked.

It caused a decline in the printing rate. Therefore, the light path of the platesetter is regularly cleaned and corrected

Ensure that the laser energy on the surface of the plate is correct to ensure the normal printing rate.

2. The plate cannot be tightly attached to the drumhead in the CTP plate making machine.

Improper energy on the surface of the plate can also lead to a decrease in the ink resistance.

3. The important role played by the pre-heating of the plate processor is that the surface of the plate has been produced.

The photosensitive layer of the photochemical reaction is further cured on the aluminum substrate of the plate to improve

The role of India rate. If the preheating temperature is too low, the photosensitive material is on the plate

The surface does not cure well, resulting in a decrease in the ink resistance.

4. The developer concentration, the temperature is too high or the development time is too long,

Corroding the photosensitive layer results in a decrease in print durability.

5. If the amount of post-wash water is insufficient during the process of printing, residual developer continues to invade.

The sensitized shadow layer causes the print rate to decrease.

6. Some protective adhesives react with the photosensitive layer, if not properly

Use CTP plate protective glue (recommended to use original protective glue), then it may also lead

Insufficient print rate.

7. If there is extreme temperature and humidity in the CTP room, it will also be in the plate

The impact of the Indian print rate.

8. If the baking temperature is too high or too low, too long or too short, it will lead to

Reducing the rate of India's decline.

Second, the printing process

(1) Effect of printing machine status on printing plate printing rate

The status of the printing press during printing is one of the main factors that affect the print durability of the printing plate

. Most of the three major forms of plate failure are related to press pressure adjustments.

1. Each type of offset printing machine is designed according to the choice of blanket lining

Printing pressure, such as hard-lined machines, the general rubber compression is about 0.1mm

. Operators sometimes choose to increase printing when false imprints appear in production

Brush pressure practices to improve, this will lead to excessive printing pressure. Pressing during printing

The sliding friction of the printing surface will greatly aggravate the wear of the printing plate and seriously reduce the printing rate of the printing plate.

In general, the design of the printing press is to make the embossing surface pure, but when printing,

Each point of the blanket is different in compression, and the corresponding actual radius of rotation is inconsistent.

The surface is inevitably subject to sliding friction, so when the printing machine is doing the drum design,

Consider the relationship between the drum radius and the lining to minimize the sliding of the embossing surface. print

During production, the lining data and pressure can not be arbitrarily changed, otherwise it is easy to increase the pressure

The sliding friction of the printing surface causes the printing plate to have a reduced printing rate.

2. The contact pressure between the ink roller and the lower ink roller is too large, and the ink roller may appear

The line speed is inconsistent with the plate cylinder speed, resulting in a difference in speed and wear on the plate

Large, thus reducing the printing rate.

3. The contact pressure between the ink roller and the printing plate is too large, which will make the print dot not clear enough

, smooth, or network expansion; in the bite at the impact of jump, there will be ink;

Accelerate the wear of the blank part of the layout or the graphic basis and reduce the printing rate of the printing plate

.

4. Different machine structures also have a great influence on the printing plate's printing rate. Sheets

The printing machine drum has a neutral angle, when the ink roller and the water roller turn over the neutral angle and the plate is connected

There is an impact on the print port at the time of touch, and the hydrophilic layer at the plate catch is more likely to wear on the dirty

. The roller surface of the web offset press is basically continuous, with the water roller and the ink roller

The impact of the mouth is much smaller, so the same type of paper, usually in roll glue

Printing capacity on printing plates will be significantly higher than that of sheetfed offset printing machines.

5. The pressure between the roller and printing plate is too light to fully supply ink

Plates, if two or more pressures are too light, can cause imprinting emptiness. If not in time

It was found that the graphic basis of the printing plate surface was not protected by the ink layer and was immersed in the wetting liquid.

Erosion eventually results in a plate fall that reduces the print durability of the plate.

(2) Printed materials

1. Adjust the ink viscosity, control the ink layer thickness, to meet the layout remaining

The protective effect of the ink layer on the printing plate basis, if the remaining ink layer is too

Thin, will increase the wear of the blanket on the printing plate, resulting in reduced printing plate printing rate. Have

When the spot color is printed, if the color of the spot color ink is too dark, the printing can only be reduced by

The method of reducing the amount of ink is to lighten the spot colors. When the amount of ink is too small, the version will appear.

The ink printing layer caused by the ink layer is too thin to reduce the printing rate.

2. Paper lint and powder fall will reduce printing plate printing rate, paper hair, paper powder will play

The effect of abrasives will therefore increase the wear on the printing plate.

3. The hardness of the surface layer of the blanket can also affect the printing plate resistance, usually eraser

The surface hardness of cloth is a little higher, which is good for the quality of the dot reduction, and the resistance of the blanket

The print rate will be higher, so companies will tend to choose harder blankets, but

The plate and blanket embossing surface wear will be heavier. We recommend when printing machine

The accuracy is better and the substrate is coated paper, and a harder blanket can be selected.

On the contrary, choose a harder blanket.

4. The aluminum plate of the printing plate is aluminum ingot rolled into aluminum plate by rolling method.

The process of elongation will break and stretch the grain of aluminum, so that the mechanical strength of the platen is in the direction of rolling

The degree will be better than its vertical direction. For sheet-fed machines, to improve with a stretch plate

Overprint accuracy, which usually causes the calendering direction of the plate to be parallel to the roller axis; and web

Machine printing speed is high, the number of prints is large, and it is easy to produce the tail-end break during the imprinting process.

The problem of the printing plate is invalid, so the rolling direction of the printing plate of the web printing press is usually vertical

Roller axial, this can use the advantages of large mechanical strength in the direction of rolling direction of the plate base, increase

Plate printing rate.

5. Use of calcium carbonate powder with higher hardness will reduce the printing plate's resistance to printing

rate.

(3) Printing process control

1. When the printing plate is in the upper machine bending plate, the size of the curved plate is inappropriate, and the printing plate cannot be printed

Evenly and tightly affixed to the plate cylinder, resulting in uneven force, it will speed up the grinding of the plate

damage. In addition, attention should be paid to the front of the plate when the plate is mounted. Foreign materials must not be stuck on the plate.

Hold the appropriate thickness.

2. The blanket cannot be stretched too tightly, and the data of the synchronous rolling ratio will be tightened

The increase in the increase, over-tightening will increase the sliding between the rollers. The blanket is stretched

Too tight will make the surface of rubber blanket lack of concession space, between rubber and printing plate

The speed difference is unavoidable. If the surface layer has concessions, then the blanket may be

With the printing plate moving together, it is easier to produce relative sliding between the printing plate and the eraser

, and the tendency to increase the weight of the plate.

3. The pH of fountain solution is usually required to be controlled between 4.8 and 5.3, when the acid is too

Weakness can easily cause printing troubles such as milk and ink over emulsification, but the acidity is too strong.

Intensify the erosion of the hydrophilic layer by the fountain solution. If it is excessively corroded by the layered text, it will

Caused by the plate to cause the printing plate to fail; if it is excessively corroded the hydrophilic layer of the blank area,

Exposing the surface of the new metal can cause the upper dirt to cause the printing plate to fail. So, dampening

When the acidity of the liquid is too strong, the printing durability of the printing plate is also reduced.