UV Curable Adhesives and Their Application (1)

Ultraviolet curing is a type of radiation curing. Radiation curing is the use of electromagnetic radiation, such as ultraviolet (UV) or electron beam (EB) irradiation coating, resulting in radiation polymerization, radiation crosslinking and radiation joining technology. A chemical process that rapidly converts low-molecular-weight materials into high-molecular-weight products. The curing is performed directly on an unheated substrate. The system contains no solvent or contains a very small amount of solvent. After irradiation, the liquid film is almost 100% solidified. (Volatile organic compounds) emissions are very low. Therefore, since the end of the 1960s, this technology has developed rapidly in the world and its products have been widely used in many industries.

I. Overview:

UV curing is a type of radiation curing. Radiation curing uses electromagnetic radiation, such as ultraviolet (UV) or electron beam (EB) irradiation to produce radiation polymerization, radiation cross-linking and radiation joining techniques. A chemical process that rapidly converts low-molecular-weight materials into high-molecular-weight products. The curing is performed directly on an unheated substrate. The system contains no solvent or contains a very small amount of solvent. After irradiation, the liquid film is almost 100% solidified. (Volatile organic compounds) emissions are very low. Therefore, since the end of the 1960s, this technology has developed rapidly in the world and its products have been widely used in many industries.

1, classification:

Radiation curing can be divided into radiation curing adhesives, radiation curing coatings, radiation curing inks according to applications. Ultraviolet (UV) light curing, electron beam (EB) curing, and visible light curing are used depending on the radiation source used. The following diagrams (1) and (2).

2, UV basic knowledge:

Ultraviolet (abbreviated as UV) is a section of electromagnetic radiation. The electromagnetic spectrum includes radio waves, red lines, visible light, ultraviolet rays, X-rays, and gamma rays. Wavelengths range from 10-14 to 106 meters, as shown in Figure 3. Ultraviolet light only has a very narrow section, and its wavelength range is 10~400nm (nm:nm, 1nm=10-9m). It can be divided into long-wave ultraviolet (UVA), medium-wave ultraviolet (UVB), short-wave ultraviolet (UVC), and ultrashort-wave ultraviolet. . The shorter the wavelength, the stronger the energy and the weaker the penetration ability.

Long-wavelength UVA, with a wavelength between 320 and 400 nm, has a strong penetrating power and can penetrate glass. This band of UV energy is equivalent to most of the chemical bond energy, and it is easy to initiate photochemical reactions. UVA is commonly used for photo-curing.

Medium Wave UVB, with a wavelength between 280 and 320, has a weak penetration and the glass absorbs it strongly. The sun is rich in UVA and UVB.

The short-wave UVC has a wavelength between 200 and 280 nm. The ozone layer absorbs it strongly. Therefore, UVC is absorbed by the ozone layer before reaching the ground. UVC has a strong destructive effect on organisms and can kill bacteria and viruses. Therefore, it is often used for disinfection.

Ultraviolet rays can damage the skin and eyes. UVA causes the skin to become dark, loose, and wrinkles. UVB produces acute dermatitis (ie, sunburn). The skin becomes red and has pain, and long-term exposure can easily lead to skin cancer. When performing photo-curing operations, precautions should be taken:

(1) The curing machine should be equipped with appropriate screens and the UV light is not easy to reveal;

(2) Appropriate personal protection, wear long-sleeved clothes, cloth work gloves, wear UV protection glasses, masks, do not look directly at the lamps.

(3) Pay attention to environmental ventilation to prevent the accumulation of ozone.

In general, there is no need to worry too much, because equipment manufacturers generally take protective equipment into account when designing, and it is okay to operate as required.