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Screen Printing Method for Paper Packaging

      Paper packaging mainly refers to cartons, cartons, paper bags, etc. used for commodity packaging, and corrugated cartons and other products used for transportation packaging. Screen printing has the characteristics of thick ink layer, rich picture and text levels, strong three-dimensional sense and wide range of printing materials.Screen Printing Method for Paper Packaging

       Its application in high-grade tobacco, wine and food packaging cartons is gradually increasing. UV screen ink is used to print sanding, refraction, ice flowers, wrinkles and other effects on the cigarette box, which greatly stimulates the purchase desire of consumers.Screen Printing Method for Paper Packaging

Screen Printing Method for Paper Packaging

Characteristics and process arrangement of screen printing

1. Screen printing process arrangement

      Screen printing is a direct printing method, and there are three process arrangements: Screen Printing Method for Paper Packaging

① paperboard → screen printing → post press processing, that is, first screen printing on corrugated paperboard or other paperboards, and then making cartons and carton products according to needs;Screen Printing Method for Paper Packaging

② Carton → screen printing, that is, screen printing directly on the produced corrugated carton or other cartons and cartons; Screen Printing Method for Paper Packaging

③ Secondary processing, that is, first screen printing on the surface paperboard, then making corrugated paperboard as needed, and then making carton and carton products. Screen Printing Method for Paper Packaging

2. Screen printing features ① wide adaptability: screen printing format can be large or small; ② Thick ink color: in all printing processes, screen printing has the thickest ink layer, high saturation and better spot color printing effect; ③ Low cost: screen printing plate making is easy and the printing process is simple; 

     Stable print quality; ⑤ Low production efficiency: slow screen printing speed, not suitable for on-line production; ⑥ Low image accuracy: screen printing resolution is not high, and the number of conventional screening lines is 24 lines / cm – 32 lines / cm.Screen Printing Method for Paper Packaging

3. Application scope of screen printing

     Screen printing is suitable for small batch production, packaging products with high printing appearance requirements, unlimited paperboard thickness and no damage to strength.

screen printing process

1. Screen plate making (1) screen selection 

① nylon screen: nylon screen has high strength, high wear resistance, high alkali resistance, slightly poor acid resistance, good ink permeability, small wire diameter, good elasticity and bright imprint;Screen Printing Method for Paper Packaging

 ② Polyester screen: polyester screen has good stability, high strength, corrosion resistance, better performance than nylon screen, high tension, suitable for high-precision printing; Screen Printing Method for Paper Packaging

③ Stainless steel wire mesh: stainless steel wire mesh has high strength, good stability, small wire diameter, high mesh, good resistance, long service life, poor elasticity, easy to crack under impact, suitable for precision printing, not suitable for curved surface printing; Screen Printing Method for Paper Packaging

④ Nickel plated polyester wire mesh: nickel plated polyester wire mesh combines the advantages of polyester wire mesh and stainless steel wire mesh, with wide applicability, moderate price and poor corrosion resistance.Screen Printing Method for Paper Packaging

     There are plain weave, twill weave, half twist weave and full twist weave. White screen is easy to cause diffuse reflection when exposed. Golden, red and amber absorb ultraviolet rays and prevent halo. The mesh number of wire mesh includes 30 mesh / cm, 40 mesh / cm, 60 mesh / cm, 80 mesh / cm, 120 mesh / cm, 140 mesh / cm and 160 mesh / cm. Screen Printing Method for Paper Packaging

      Generally, the mesh number is large and the straight diameter of wire mesh is small. Fine wire dense network, high resolution; Coarse wire and coarse mesh have low resolution. When printing curved surfaces, use elastic wire mesh, such as nylon mesh; When printing the substrate with large absorption, use the screen with large mesh area; Screen Printing Method for Paper Packaging

     When printing smooth surface, use high elastic and high tension screen; When printing rough surface, use low mesh screen; When printing high-precision prints, use screen with low elongation and high tension; When printing signboards, textiles and knitwear, use 28 mesh / cm – 78 mesh / cm screen; When printing paper, metal, glass, leather and plastic, use 40 mesh / cm – 140 mesh / cm screen.Screen Printing Method for Paper Packaging

(2) Stretch net

      The screen frame includes wood frame, metal frame, plastic frame, combination frame, etc. When the net is stretched, the net frame shall be cleaned first. The net can be stretched manually, mechanically or pneumatically, and then bonded and trimmed.Screen Printing Method for Paper Packaging

      The tension of the wire mesh shall be appropriate, uniform and stable, the wire direction shall be consistent, oblique pulling shall be avoided, and the warp and weft wires shall be parallel.Screen Printing Method for Paper Packaging

(3) Plate making

① Direct method: screen cleaning → coating photosensitive adhesive → plate printing → development → plate revision. This method takes time to apply glue, the film thickness is adjustable, the combination is firm, the printing is resistant, and the pictures and texts are easy to be sawtooth. Screen Printing Method for Paper Packaging

② Indirect method: photosensitive diaphragm → plate printing → development → film patch → uncovering film base → plate revision. This method has complex operation, smooth lines, weak film, low printing resistance and constant film thickness. Screen Printing Method for Paper Packaging

③ Mixing method: screen cleaning → film coating → plate printing → development → plate revision. This method has the advantages of simple operation, fixed thickness, smooth and firm lines.Screen Printing Method for Paper Packaging

(4) Screen direct plate making

      Screen direct plate making is referred to as CTS (computer to screen). ① Laser ablation direct plate making: first, apply the screen photosensitive adhesive on the metal mesh, burn through the photosensitive layer with the laser, and the mesh of the graphic part is transparent. The ablation place is controlled by the computer of the prepress system. Screen Printing Method for Paper Packaging

      This method can only be used for the metal mesh. ② Laser exposure direct plate making: first, apply photosensitive adhesive on the screen, and the prepress system computer controls the laser to image on the screen to make the screen plate. This plate making method uses a special photosensitive adhesive, the ultraviolet light wave range is narrow, and the price of the laser exposure system is high. ③ Inkjet imaging system: Screen Printing Method for Paper Packaging

      first apply photosensitive adhesive on the screen, and the prepress system computer controls the inkjet system to spray light blocking ink onto the photosensitive layer of the image and text, and then fully expose to ultraviolet light. If the image and text part is not photosensitive, wash off the photosensitive adhesive; Photosensitive hardening of blank part. This method can use ordinary photosensitive adhesive without losing the details of the image.Screen Printing Method for Paper Packaging

2. Screen printing machine

     Screen printing machines include manual screen printing machine, semi-automatic screen printing machine and full-automatic screen printing machine. There are also uncovering type, worktable lifting type, sliding table, roller worktable, arc worktable, curved surface type, roller screen type, double roller type and other screen printing machines, which can be selected according to needs.Screen Printing Method for Paper Packaging

3. Special screen printing method

① UV imitation metal etching printing UV (ultraviolet) imitation metal etching printing is to print a layer of uneven translucent ink on the substrate with metal mirror luster, and then solidify it through ultraviolet light to produce an effect similar to the etching or sanding of bright metal surface. 

     Printed products are elegant and luxurious, which are used for high-grade and exquisite packaging. This printing method uses UV curing imitation metal etching ink, the substrate is gold card paper, silver card paper or composite material, and the screen is 70 mesh / CM-100 mesh / cm.Screen Printing Method for Paper Packaging

 ② UV wrinkle pattern ink printing UV wrinkle pattern ink printing is to use UV wrinkle ink to print on the surface of the substrate, after UV curing, to form a special wrinkle pattern decorative effect. This printing method uses 40 mesh / cm – 60 mesh / cm screen, and the ink film is 20 thick μ—— thirty μ, The effect is better when the thickness is large.Screen Printing Method for Paper Packaging

 ③ Ice flower effect printing ice flower effect printing is to use silk screen printing to print ice flower ink on the surface of the substrate with metallic luster. After UV curing, it presents ice flower shape. The substrate of this printing method is gold and silver cardboard, using 60 mesh / cm – 100 mesh / cm screen.Screen Printing Method for Paper Packaging 

④ Foaming printing foaming printing uses microsphere foaming ink and screen to print on paper or other substrates. The graphics and texts are raised. It is widely used in book binding, Braille, map, packaging and decoration. Screen Printing Method for Paper Packaging

      This printing method uses 30 mesh / cm – 50 mesh / cm screen. The screen can also be used for fragrance ink screen printing, pearlescent ink screen printing, liquid crystal ink screen printing, phosphorescent ink screen printing, fluorescent ink screen printing, crystal luster screen printing, etc.Screen Printing Method for Paper Packaging