What is the impact of screen color on plate making?

 

Screen has white, yellow, amber, red and so on.The color of the screen has a great impact on the quality of plate-making.Colored screen, such as: yellow, red, amber screen, printing can play to prevent the diffuse phenomenon of light, and the use of white screen printing will appear obvious diffuse phenomenon.This is because, photosensitive material in the ultraviolet region has a large absorption peak, because the white screen in the light source in the irradiation of the reflection is white light, so the photosensitive material has an impact.Irradiation light by Yang figure film transparent part to the emulsion coating, exposure light reflex during contact with white silk screen and inflectional, reflection, diffuse reflection phenomenon, make plate floating shoot phenomenon in which halation if use colored silk screen will prevent this kind of phenomenon because of color screen can absorb part of the irradiation light, thus reducing the exposure of light reflection intensity, and colored silk screen reflection is light, the light is not active, so won’t impact the sense of material, especially the fine print when printing, silk screen color is particularly important.

 

What is the relationship between the mesh number and network points?

 

The number of mesh points and network points only in the replication of the continuous adjustment of the original manuscript to form a certain relationship.Screen printing technology to copy the continuous tone color manuscript, if it is a direct use of the continuous tone photographic plate to print the screen plate and printing can not be the same as the original continuous tone copy.Because screen plate only presents two states, that is, the part of the picture and text mesh is through, non – picture and text part of the mesh is closed.Not because of a specification of the size of the silk mesh and arrangement rules are uniform, so the printing ink through the silk mesh is basically the same.So that the original text can not show the level of change.In order to make the depth of the original pattern changes can be fully reflected in the screen plate, it is necessary to make the continuous adjustment of the original into dot negative.Change the depth of the original, with different sizes, uniform density of ideas to represent.Screen printing plate density of the highest part of the point in the area, the density of the low part of the dot area is small, the density of the same part of the dot area is also the same, the idea and the idea of the center of the distance between the same, and according to a certain Angle regularly arranged.With this dot negative drying screen printing plate and printing, you can get a continuous tone copy.The density of dot arrangement is usually expressed by the number of network lines.The unit representation is line/inch or line/centimeter, which means the number of dots arranged in a unit length.

 

What is the process of stretching the mesh?

 

Tension is the first process of making screen printing plate.The quality of the tension network has a direct relationship with the quality of plate making.Therefore, we must be careful and careful to do the preparation work and tension before the network.

 

Tension network according to the first printing size chosen the corresponding net frame, the screen frame and screen adhesive side to clean, if it is the first time to use net frame, need to use a sandpaper friction gently, so that the net box surface is rough, so easy to increase the screen frame and screen the relay, if it is used by the network box also want with sandpaper friction clean, remove residual glue and other substances.After cleaning the screen frame in the tension before the network, the first contact with the screen surface of a pre-coated adhesive and dry.When stretching the net, with manual or mechanical stretching the net, the screen tensioning screen and screen frame, and in the screen and screen frame contact.Part of the coating adhesive, and then blow dry, pay attention to the adhesive is not suitable for coating too thick or too thin, in the blow dry, you can use rubber board or soft cloth, wipe the adhesive part, the edge of a certain pressure, so that screen and screen frame bonded more firmly.After waiting for glue dry, loosen the external tension, cut net frame around the screen outside, and then use the single side adhesive tape post in the part of the screen and screen frame adhesive, which can protect the screen and screen frame, can also prevent printing solvent or water to dissolve glue, to ensure the effective use of screen plate.Finally, wash the screen with water or cleaning agent, to dry the screen, can be used for photosensitive adhesive coating (plate making).

 

How many ways are there to stretch the net?What are their characteristics?

 

Tension screen is an essential process to make screen printing plate.Stretch the net, is the screen in a certain tension firmly fixed on the screen frame.And make the tension of the good screen has a certain tension, in order to meet the photosensitive coating and other plate making requirements.Screen tension and tension screen quality, but also has a direct impact on the quality of printing.Color printing, the requirements of color screen printing plate each color plate tension must be kept basically the same, so as to ensure the accuracy of overprinting.Only good network, to ensure the quality of plate making and printing.There are mainly manual tension net and mechanical tension net two methods.Manual tension is a simple and traditional method.Usually used for wooden mesh frames.This method is through manual nail, wood, adhesive and other materials will be fixed on the screen on the wooden frame.Manual tension tension can generally meet the requirements, but the tension is not uniform, to do more trouble, time-consuming, tension quality is not easy to guarantee.This method is mostly used in a small number of printing and printing accuracy requirements are not high.

 

Mechanical tension is the use of mechanical force, so that the screen tension, with an adhesive will be firmly bonded with the screen frame together.After the adhesive is dried, take off the mesh frame and seal the edge with the single-side pressure sensitive adhesive paper of polyester film.Prevent the adhesive from dissolving and make the screen plate look clean.All kinds of material frame can be used mechanical tension net.Mechanical tension tension network has uniform tension, tension network short time and other characteristics.Easy to grasp the required tension.Suitable for plate making with high precision.

 

How to choose the Angle of tension net?

 

Stretch the net Angle refers to the screen, weft line (silk) also screen frame edge included Angle.

 

There are two forms of tension net, one is tension net, the other is diagonal tension net.The following two methods are described respectively.

 

Is stretching the net, is the weft line of the screen parallel and vertical to the four sides of the frame.Namely through, weft line and screen frame edge 90 degrees.

 

Skew stretch network, refers to the screen, weft line and the four sides of the screen frame is a certain Angle.The use of positive tension network form tension network, operation is more convenient, because can make full use of the screen, can save the screen leftover material.Reduce screen waste.However, in color printing using this form of tension screen plate prone to moire, so generally do not use tension screen color printing.The use of slanting tension network to improve the quality of printing, to increase ink leakage also has a certain effect.Its deficiency is the screen waste is larger.In the printing accuracy and color printing, the selection of tension screen Angle has a direct impact on the printing quality, tension screen Angle is not suitable, will appear moire.Therefore, half of the copy of the printing, often applicable stretch screen Angle is 20 degrees – 35 degrees, in the printing of high resolution circuit board, due to the use of a higher number of wire mesh, so stretch screen Angle selection of 45 degrees is more suitable.In the actual tension network, in order to reduce the waste of the screen, the general reproduction of printed matter using tension network.

 

How to determine the tension of wire mesh?

 

Screen printing accuracy is related to screen printing plate accuracy, and screen tension is one of the important factors affecting screen printing plate quality.Screen tension and screen frame material and strength, screen tree, temperature, humidity, tension method.Usually in the manual tension net and no tensiometer, the tension is determined mainly by experience, when the tension net will stretch the screen, and at the same time with the finger pressure screen, generally with the finger pressure screen, feel that the screen has a certain elasticity can be.

 

In the use of tension screen machine and large screen frame tension screen, the general use of tension meter test screen tension.

 

In the use of tension network machine tension network, because tension network chuck movement (tension debugging) is through the barometer to control the realization, so different texture of the screen, its tension network pressure value is different.Generally, the tension pressure of silk mesh is 7-9kg/cm2: the tension pressure of nylon mesh is 8-10kg/cm2; the tension pressure of polyester mesh is 8-10kg/cm2; the tension pressure of polyester mesh is 8-10kg/cm2.The pressure of stainless steel wire mesh is 10-13kg/cm2.

 

The above are several kinds of screen in tension network pressure reference value, tension network can refer to these data according to the actual situation of tension network, in order to obtain a more ideal tension network.

 

What kinds of adhesives are commonly used in stretching nets?

 

Stretch the net with the role of adhesives so that the screen and frame firmly bonded together.Adhesive network with more kinds of adhesives, in the selection, according to the material of the frame, screen type, choose different adhesives.The main adhesives used for stretching the mesh are polyvinyl acetal (PE), vinyl perchloride, rubber adhesives, phenol-neoprene, nitrile rubber, etc.