Paper Bag With Ribbon offset plate and its process control considerations

Paper Bag With Ribbon offset plate and its process control considerations

The competition of printing industry is more and more fierce, and the technology of offset printing is more and more mature. In order to improve the quality of products, it is often necessary to start from the printing details, careful and thoughtful consideration of the production of auxiliary materials and technology. Offset printing has the characteristics of small printing pressure, small printing deformation value, good reproduction effect of the original manuscript, soft tone, clear dot, rich printing level, fast printing and less loss, so it is widely used in the printing of various products, especially suitable for printing color transition dot plate, line, small text, etc. Now combined with my years of work experience, for the control of offset printing technology, and the industry peers to discuss.

First, design and plate making technology control

1. The printed field layout should avoid containing small text, lines and transition dots in the same color version, so as not to produce paste version, dot expansion or ink layer is not thick enough due to pressure and ink volume, which will affect product quality.

2. There are overprinting parts between the printing plates, and the overprinting edge of one of the plates should be properly expanded and shrunk to overcome the phenomenon of the edge "exposed" due to the inaccuracy of overprinting.

3, four-color printing, plate output film must pay attention to the Angle of the network cable. Generally, the Angle of the network cable is Y90°, M45°, C75°, and K15°. Generally, the Angle of the network cable in the main tone version is 45°.

Two, printing technology control

1. Temperature and humidity control of printing environment.

Controlling the temperature and humidity of the production workshop is an important part of improving the accuracy of product overprinting. The temperature and humidity of the offset printing workshop should be kept relatively balanced and the temperature should be kept between 20℃ and 25℃, and the humidity should be kept between 50% and 60%.

2. Reasonable selection of offset PS version. PS plate plays an important role in offset printing, it is mainly composed of two parts of the sensitive layer and plate base, the thickness is generally 0.15mm~0.3mm, the sensitive layer after exposure should have good oil philicity, plate base should have good hydrophilicity. PS version should meet the layout flat, uniform thickness, size stability, not easy to deformation, clean surface, dot reduction is good, high printing resistance, printing ink balance, not easy to dirty and other basic performance.

3. Reasonable selection of rubber blanket. As the medium of imprinting transfer, rubber blanket has great influence on the quality of offset printing products. The correct selection of rubber blanket plays an important role in improving product quality. The blanket consists of synthetic rubber and textile cloth. The textile cloth layer is usually made by sticking 3 to 4 layers of fabric onto the synthetic rubber. The selection of rubber blanket should be based on the principle of good appearance quality, high flatness, good elasticity, good ink transfer, small compression deformation, high tensile strength, small elongation, good surface rubber characteristics. In addition, different types of blanket should be selected according to different printing and printing materials, ink and text.

4. Balance control of offset ink. There are many factors affecting the balance of offset ink, including imprinting ink layer thickness, printing paper properties, ink properties, workshop temperature and humidity, moistening solution, etc. In particular, the pH value and conductivity of the moistening liquid directly affect the quality of the printing plate, ink drying speed, interfacial tension, etc. Under normal circumstances, moistening liquid conductivity should be between 800μΩ/cm~1200μΩ/cm, preferably between 800μΩ/cm~900μΩ/cm, if higher than 1200μΩ/cm will make the emulsion intensified, resulting in dot blur; If less than 800μΩ/cm will cause a dry version, so that the blank part of the print dirty. Moistening version of the liquid pH value should be maintained between 4.5 and 5.5, when the dot is the most clear. If it is below 4.0, it is easy to drop the version, and higher than 5.5, it is easy to paste the version. Therefore, to control the balance of ink and wash, is to use as small as possible to run the version of the liquid supply, so that the printing is attached to a thick enough amount of ink, should avoid the use of "ink and water" balance method printing.

5. Control the color sequence arrangement of offset printing. At present, the printing color sequence is not uniform. In actual production, the printing color sequence should be determined according to the characteristics of the sample, ink, paper, etc., and the specific situation of the production workshop. Under normal circumstances, the printing color sequence arrangement should follow the following principles: the ink color with strong hiding power is printed first, and the high transparency is printed after; Ink quantity small print first, ink quantity large after printing.

6. Protection of semi-finished printing products and control of production cycle. A high quality product, according to its product characteristics will often use a combination of multiple processes of production, in the production process will inevitably appear multiple printing and stamping, concave and convex, die cutting and other combination process. If the temperature and humidity in the production workshop is not stable, plastic film should be used to seal the semi-finished product at this time, so as to avoid the expansion and deformation of the printing product, resulting in the following process overprinting is not allowed. At the same time, according to the production schedule of the product, reasonable production cycle, each process closely connected, reduce the production workshop area rate, improve production efficiency.