Paper Packaging Screen Printing Methods

Paper packaging refers mainly to cartons, cartons, paper bags, and other products used for product packaging. And corrugated and other products used for transportation and packaging. Screen printing has the characteristics of thick ink layer, rich graphic layers, strong three-dimensional sense, and wide printing materials, and has gradually increased in the application of high-end tobacco and alcohol, food packaging cartons. The use of UV screen inks to print scrubs, refractions, ice and wrinkles on cigarette packs has greatly stimulated consumers’ desire to purchase.

Screen printing features and process arrangements

1. Screen Printing Process Arrangement

Screen printing is a direct printing method, there are three kinds of process arrangements:

1 Cardboard → Screen Printing → Post-press processing, that is, first screen printing on corrugated cardboard or other cardboard, and then making cartons and cartons as required;

2 cartons → screen printing, ie screen printing directly on already prepared corrugated boxes or other cartons or cartons

3 secondary processing, that is, first screen printing on the surface board, and then made into corrugated cardboard according to need, and then made into cartons, cartons products

2, screen printing features

1 Wide adaptability: Screen printing format can be large or small;

2 Ink thick: In all printing processes, the screen printing ink layer is the thickest, the saturation is high, the spot color printing effect is better;

3 Low cost: screen printing plate making easy, the printing process effect is simple;

4 print quality and stability;

5 low production efficiency: screen printing speed is slow, not suitable for online production;

6 Low image accuracy: screen printing resolution is not high, the number of conventional screen lines 24 lines / cm ~ 32 lines / cm

3, the scope of application of screen printing

Screen printing is suitable for small batch production, high printing appearance requirements, unlimited cardboard thickness, no damage to the packaging products

Screen printing process

Screen printing

(1) Screen selection

1 Nylon wire mesh: Nylon wire mesh has high strength, high abrasion resistance, high alkali resistance, slightly poor acid resistance, good ink permeability, small wire diameter, good elasticity, and vivid marking;

2 Polyester silk screen: Polyester silk screen has good stability, high strength, corrosion resistance, and its performance is better than nylon screen. It has high tension and is suitable for high-precision printing;

3 Stainless steel wire mesh: Stainless steel wire mesh has high strength, good stability, small wire diameter, high mesh resistance, long service life, poor elasticity, easy to break by impact, suitable for precision printing, and not suitable for surface printing;

4 Nickel-plated polyester mesh: Nickel-plated polyester mesh combines the strengths of polyester mesh and stainless steel mesh. It has wide applicability, moderate price, and poor corrosion resistance.

The screen has a plain weave, a twill weave, a half weave, and a full weave

White screens can cause diffuse reflection when exposed, and golden, red, and amber absorb ultraviolet light, which can prevent halation.

The number of screen meshes is 30 mesh/cm, 40 mesh/cm, 60 mesh/cm, 80 mesh/cm, 120 mesh/cm, 140 mesh/cm, 160 mesh/cm, etc. In general, mesh The number is large and the wire diameter is small.

Filament dense mesh, high resolution; coarse wire fine mesh resolution is low. When printing curved surfaces, use a large flexible screen, such as nylon mesh; when printing large absorbent substrates, use a screen with a large mesh area; when printing smooth surfaces, use a high elasticity, high tension screen; printing rough surface When using low-mesh screens, use low-elongation, high-tension screens when printing high-precision prints, and use 28 mesh/cm~78 mesh/cm mesh when printing signs, textiles, and knitting; For mesh, metal, glass, leather, and plastic, use 40 mesh/cm to 140 mesh cm.

(2) stretch net

Screen frame net frame has wooden frame, metal frame, combo box and so on. When the net is stretched, the net frame is first cleaned, and the net can be manually, mechanically or pneumatically used, and the net is selected to be bonded and trimmed.

Stretch net requires proper screen tension, uniform and stable, uniform wire, avoid oblique pull, and the warp and weft yarns are parallel to each other.

(3) Plate Making

1 Direct method: Screen cleaning → Photosensitive adhesive → Printing → Developing → Retouching. This method is time-consuming coating, adjustable film thickness, combined with a solid, resistant to India, the image is easy to saw out.

2 indirect method: feel light film → print version → development → film → exposing film base → revision. This method is complicated to operate, the lines are smooth, the film is not strong, the resistance to printing is low, and the thickness of the film is constant.

3 mixing method: screen cleaning → foil → printing → development → revision. This method is easy to operate, has a fixed thickness, a smoother line, and is more rigid.

(4) Direct Screen Plate Making

The screen is directly referred to as CTS (Computet To Screen).

1 Laser Ablation Direct Platemaking: Firstly, a wire mesh is applied on the wire mesh to feel the light glue, and the laser is used to burn the light sensing layer. The mesh of the graphic part is transparent, and the prepress system controls the ablation place. This method can only be used. On metal mesh.

2 laser exposure direct plate-making: first coated with photosensitive emulsion on the screen, pre-press system computer-controlled laser imaging on the screen, made of screen version. This plate-making method acts on a special photo-resist, the ultraviolet light wave range is narrow, and the laser exposure system is expensive.

3 inkjet imaging system: first coated with photosensitive emulsion on the screen, pre-press system computer-controlled inkjet system to block light on the photosensitive layer is not part of the photosensitive layer, and then full UV exposure. The part of the image is not sensitive, and the photosensitive resist is washed away; This method can use ordinary photosensitive adhesive, without missing the details of the image.

1, screen printing machine

Screen printers have manual screen printers, semi-automatic screen printers, and automatic screen printers. There are also open-book type, table lift, slide table, roller table, curved work table, curved type, roller screen type, double drum screen printing machine, according to the need to choose.

2. Special screen printing method

1UV imitation metal etching printing

Uv (ultraviolet) imitation metal etching printing is to print a layer of rugged semi-transparent ink on the printed material with a metallic mirror gloss. After ultraviolet curing, it produces an effect similar to that of a polished metal surface that is etched or frosted. Printed products are elegant, luxurious, used for exquisite high-end packaging.

This printing method uses a UV-curable imitation metal etching ink, the substrate is gold cardboard, silver cardboard, or a composite material, and the screen mesh is 70 mesh/cm~100 mesh/cm.

2uv wrinkle pattern ink printing

UV wrinkle pattern ink printing is the use of UV wrinkles ink printed 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 mesh, and the ink film thickness is 20~30μ.

3 ice effect printing

The effect of ice printing is on the surface of the substrate with metallic luster. The ink with ice print is printed on it by silk screen printing, and after being cured by ultraviolet rays, it is in the form of ice flower.

The printing material of this printing method is a gold and silver cardboard, and a mesh of 60 mesh/cm~100 mesh/cm is used.

1 foam printing

Foam printing is the use of micro-ballooning inks, which are printed on paper or other substrates with silk screens. The images are raised and widely used for printing books, braille, maps, and packaging.

This printing method uses 30 mesh/cm to 50 mesh/cm mesh.

Screens can also be used for scented ink screen printing, pearl ink screen printing, liquid crystal ink screen printing, phosphor ink screen printing, fluorescent ink screen printing, crystal glossy screen printing and so on.

High-speed rotary screen printing production line

Due to the flat press screen printing method, the printing speed is low, the ink curing speed is slow, the printing quality is difficult to control, and the printing material consumes a large amount, which can not meet the needs of cigarette cartons for scale and mass production. High-speed rotary screen printing production line, fast printing speed, high productivity, stable quality of printing products, low consumption, change the traditional flat pressure flat screen printing, manual feeding, ink supply, suitable for high-speed automatic, large-scale mass production of exquisite Fold the tray.

Web Rotation Screen printing uses a nickel metal round screen plate, a built-in squeegee, and an automatic ink supply system. The squeegee transfers the printing ink from the stencil to the surface of the substrate supported by the impression cylinder. The entire printing process from paper feeding, ink supply, color registration, UV drying, etc. are fully controlled by the computer.

The round screen printing plate is suitable for large-format rotary printing, the maximum speed can reach 125m/min, and the screen can be used repeatedly. Therefore, web rotary screen printing can not only meet the requirements of special effects such as printing frosting and ice flower, but also can be used to hot-stamp holographic anti-counterfeit labels, embossed dentifrices and die-cutting indentations, and it is easy to realize high-speed automatic printing paper boxes.

Source: Screen Printing Author: Tangwan have