Surface Treatment Process of Silicone Products

What is silicone?

Silica gel is a highly active adsorbent material, which is amorphous and contains polysiloxane, silicone oil, silica (silicon dioxide), coupling agent and filler, etc. The main component is silicon dioxide. It is insoluble in water and any solvent, non-toxic and tasteless, chemically stable, and does not react with any substance except strong alkali and hydrofluoric acid. Various types of silica gel have different microporous structures due to different manufacturing methods. The chemical components and physical structure of silica gel determine that it has many characteristics that are difficult to replace by other similar materials: high adsorption performance, good thermal stability, stable chemical properties, high mechanical strength, etc.

Classification of silicone

1. According to the different composition can be divided into: one-component and two-component silicone.
2. According to the vulcanization temperature, it can be divided into: high temperature vulcanization and room temperature vulcanization silicone.
3. According to the form of the product, it can be divided into: liquid and solid silica gel.
4. According to the vulcanization reaction, it can be divided into: condensation reaction type, platinum addition reaction type and peroxide curing type.
5. According to the main chain structure, it can be divided into: pure silica gel and modified silica gel.
6. According to the characteristics of the product can be divided into: high and low temperature resistance, anti-static type, oil and solvent resistance, conductive type, foam sponge type, high strength anti-tear type, flame retardant and fire resistant type, low compression deformation type, etc.

Silicone surface treatment process

Screen printing

Screen printing is the abbreviation of screen printing, which is one of the four major printing techniques. The screen is prefabricated by filming exposure etching, called: sunscreening. The number of mesh holes per square inch is called mesh count, and the higher the mesh count, the higher the requirements for ink quality. With its wide range of applications, ease of operation and low price, screen printing occupies almost the majority of the market share for logos and simple designs for mass-produced products.

Features

• Screen printing can be used for the surface construction of almost any material and paint film.
• Can be operated by a single person, and can be put into production on the same day of training for novices, with extremely high single-person output and throughput rates.
• Simple equipment with low production environment requirements.
• simple and repetitive movements to operate the equipment.
• wide range of raw material sources, rich types, low procurement costs.
• Slightly inferior texture and lower sensory grade of muscle texture.

Design points

1. If screen printing is required, the product should not have overly complex curved surfaces and too deep concave surfaces, otherwise the mesh will be unreachable or the ink will be difficult to control.
2. When designing and using screen printing, it is not recommended to use multi-color or gradient-type colors.
3. Screen printing can only work with one color at a time, and each color more than one needs to open a screen, called "color separation"; each color screen operates separately in the screen printing process, called "color registration". Due to the accuracy of the screen printing process itself, color registration is prone to inaccurate color registration, so screen printing is generally not recommended for the construction of multiple colors or gradients of complex colors.

Pad printing

Pad printing is a supplemental extension of screen printing means, belongs to one of the special printing methods. It can print text, graphics and images on the surface of irregular shaped objects, and is now becoming an important special printing. Such as text and graphics on the surface of cell phones, and the surface printing of many electronic products such as computer keyboards, instruments, meters, etc., are done by pad printing.

Features

• Pad printing can be applied to parts that cannot be processed by screen printing, such as recesses and the back of workpieces.
• the accuracy of pad printing patterns is relatively high because there are no restrictions on the number of mesh for screen printing
• pad printing machine is automatic equipment, can be set color printing, convenient operation, fully automatic operation of the equipment.
• low cost, except for more expensive equipment, other cost factors are basically the same as screen printing
• ordinary effect, there is an area limit, the production scale has an upper limit, can not produce an area too large pattern.   

Design points

1. As the silicone pad printing head relies on elasticity to work and there is an upper limit to the production size, the design should consider that pad printing cannot produce patterns with too large an area.
2. The design should consider the color scale limitation. Although pad printing can be operated in sets of colors, it is still difficult to produce gradient colors because of the clear edges of the grooves processed by steel plate corrosion.

Heat transfer printing

Heat transfer printing is a technique of printing patterned patterns onto heat-resistant adhesive paper and printing the patterned patterns of the ink layer onto the finished material by heating and applying pressure. Using thermal transfer film printing can be multi-color patterns into a picture at once, without the need to set the color, simple equipment can also print a realistic pattern. Heat transfer printing is generally divided into billion and heat transfer printing and digital heat transfer printing, billion and heat transfer printing is suitable for large quantities of printing, can be applied to ABS, PE, PP, EVA, leather, stainless steel, glass, wood, coated metal; digital heat transfer printing is suitable for small quantities, do their own characteristics of the product, can be applied to ABS, PP, leather, ceramic coated cups.

Features

• Wide range of applications, can be constructed on almost any material surface.
• Large complex and rich color patterns can be made because the patterns are printed.
• conventional thermal transfer can allow the workpiece to have a regular curvature or even a column surface.
• Slightly lower accuracy, thermal transfer construction by heating the transfer film under pressure through the heat generating medium, although there are electronic eyes, positioning holes and other auxiliary positioning means, but the material expansion rate and stretching rate fluctuations will still affect the positioning accuracy of the pattern, curvature changes dramatically local, such as sharp corners or sharp edges, may lead to pattern deformation, chafing.

Design points

1. Not all goods can be printed with heat transfer to create patterns, involving factors such as heat resistance and smoothness of the goods.
2. Be very suitable for printing pictures that require color transition.
3. Suitable for professional use in more raw industries.
4. Suitable for the printing of multiple materials.

Water transfer printing

The principle of water transfer printing is somewhat similar to thermal transfer printing, but the operating medium used is water, hence the name water transfer printing. Water transfer printing is further divided into two categories according to the details of operation: water cloak transfer printing and water sticker printing. The principle of indirect printing and perfect printing effect solves many problems of product surface decoration, mainly used for a variety of complex shapes of the product surface graphics transfer.

Features

• Any natural patterns and photos and graphics files can be transferred on the products.
• Simple operation, can be manual or automatic machinery.
• Restricted by sink and site, suitable for small batch production with deep customization.
• There is a certain degree of uncertainty, relying on a large number of manual people for post-processing such as repair.
• The cost is slightly more expensive than silk-screen printing and similar to heat transfer.

Design points

1. This technology can be considered when the product involves complex curved surfaces and dead-end printing. This technology can overcome the complex shape of concave and convex and the dead angle of printing that cannot be overcome by traditional printing and thermal transfer, pad printing and screen printing.
2.  It relies on water surface tension, and different curves, angles, and sink positions can have unexpected effects on the transfer film, so it is not suitable for products that require high dimensional/position accuracy and consistency.

Digital Printing

Digital printing, also known as flatbed printing / universal printing, is a fast process that modifies traditional inkjet / thermal sublimation printers by adding a working surface and XY axis ball screw to allow them to work on most flat workpieces.

Classification

Digital printing is currently divided into two categories according to the nature of the ink: thermosetting inks and UV inks, with some other micro-innovation differentiation in the industry that does not affect the classification properties of the process. Heat-set ink output ink point is relatively small (0.02 ~ 0.05mm), the imaging is clearer, the color scale is deeper, the color is relatively rich. UV type ink output ink point is coarse (0.05 ~ 0.1mm), the imaging is slightly blurred, the color scale is shallow, the color is not as delicate and rich as the heat-set. The advantage is to take UV light curing, while printing irradiation curing construction speed, excellent performance, good adhesion, relatively broad application prospects.

Features

• Simple process, no need to make a film plate, full-color once imaging.
• Precise positioning, zero scrap rate.
• Can be produced quickly on a small scale.
• no direct contact with items, ensuring the integrity of printed items and no deformation due to heat and pressure, etc.
• Digital printing machines are more expensive than traditional printing machines, with high fixed costs.

Laser

Lasers are an emerging field of high technology that can be found in almost every aspect of daily life. In addition to measurement/inspection, lasers have a wide range of applications and a promising future in the industrial field, such as cutting in forming processes and welding in joining processes.