Synthetic Paper Printing and Postpress (Part 2)

Although synthetic paper can use a paper/polyester plate at the time of printing, metal plates and pre-printed resin plates are still a better choice. When using paper/polyester plates, care should be taken that some additives delay or prevent the ink from drying out.

Fountain solution

The balance of water and ink is the most important factor affecting the offset quality. You can use 11% to 15% alcohol fountain solution, or add other alcohol solvents in the fountain solution to help improve the printing quality. It is recommended that the fountain solution be maintained at a pH of 5.5-6.0 and maintained at a temperature of 48-59°F. Since the synthetic paper does not have the absorption properties of the paper, the amount of water supplied on the printing plate should be reduced by 10% to 20%, otherwise the ink drying will be affected.

Dusting

It is recommended to use a fine powder with a particle size of 400 meshes for dusting, but it is not possible to use a commonly used 300-gloss matte starch type dusting powder. It is recommended not to use soluble powder, because these dusting is not enough to prevent the ink from getting dirty.

Stacking

The paper stack height is generally 9 inches, but it is recommended that the height of the synthetic paper stack should not exceed 7-8 inches, and the ideal stack height is 6-7 inches. Do not perform any treatment on the printed sheet before thoroughly drying.

dry

In order to avoid ink smudging and to print further, a drying time of at least 3 to 5 hours is required. Before the synthetic paper is cut, coated, and post-processed, there must be at least 12 hours of thorough drying time. If suitable UV inks are used, the drying time can be shortened. Similarly, the use of electron beam and infrared drying can also increase the drying speed. During drying, the temperature should not exceed 150°F in order to maintain the dimensional stability of the synthetic paper. Compared with paper, printing pressure can be reduced by 5% to 10%.

Postpress

Polylith synthetic paper can adapt to a variety of post-press processing methods, such as paper cutting, slitting, die cutting, drilling, punching, punching, buckles, embossing, hot stamping, and folding.

Cut paper

Polylith synthetic paper can easily achieve the same paper cutting accuracy as paper, and the cutter used should remain sharp. In addition, since the synthetic paper has a certain compressibility, a lighter clamping pressure should be used.

Die cutting

The die cutter used for die-cut synthetic paper should be hardened and hardened, and its Rockwell hardness should be at least 55 degrees, while the normal paper hardness used is 45 to 48 degrees. The famous die cutter suppliers Austria Bonna and Sweden Sandvik can be selected. In the selection of the blade angle, the standard 60-degree blade angle can be selected for the cutting of thin materials; the material thickness of 0.008-0.014 inches can select the blade angle of 52 degrees; the material with the thickness over 0.014 inches is recommended to select 42 Degree of blade angle.

Drilling, punching

Polylith synthetic paper can be drilled and punched. The cutting knife should be sharp enough, because the irregular edges cut by the blunt knife will greatly reduce the initial tear strength. During the drilling process, the heat generated will cause the edge of the synthetic paper to melt. In order to reduce the amount of heat generated, an additional short residence time may be added. The drill bit should be sharp and the stacking height should not exceed 1 inch when drilling.

folding

Polylith synthetic paper can be folded on an ordinary folding machine just like the same bulky paper. In the production of books and periodicals, synthetic paper can be folded into 16 pages or less. If there are more pages, some experimentation is required.

Indentation

Synthetic paper cannot be indented like ordinary paper. It must be ensured that the indentation is made in the transverse direction, not in the longitudinal indentation.

Binding

Polylith Synthetic Paper uses a suitable hot melt adhesive for wireless binding. To increase adhesion, some grooves can be engraved at the spine.

Polylith synthetic paper can also use coil stitching, but it should be especially careful when punching and punching. Polylith Synthetic Paper can also be saddle-stapled on the sewing machine.

Adhesion

Polylith synthetic paper can be bonded to each other and can be bonded to other materials. Adhesives that can be used include synthetic resin adhesives, solvent adhesives, or hot melt adhesives.

Heat seal

Polylith synthetic paper itself can be heat sealed. At 150°C, the seal strength is very high. Different types of synthetic paper, you can choose different heat sealing process.

Coating and coating

(1) Use 100% solids ink, mineral oil content should not exceed 3%, can be dried by oxidation.

(2) If the graphic needs to be coated or embossed, the use of wax-free ink is required.

(3) Use a new ink with a higher color intensity.

(4) When coating or gluing, the printed synthetic paper should be tested for compatibility under end-use conditions.

(5) Polylith pre-coated synthetic paper can be coated in-line with water-based coatings.

However, on-line waterborne coating is not recommended for non-precoated synthetic paper unless the press is properly tuned to ensure effective drying.

Source: Print Materials Business in China Compiled by Hao Fayi, School of Publishing and Printing, University of Shanghai for Science and Technology