UV adhesive can be roughly divided into two categories: substrate (adhesive tape, double-sided adhesive tape) and substrate-free (liquid glue). The latter is cured by UV light when used, while the former can increase or decrease the adhesion. As temporary protection or temporary positioning, UV adhesive tape has great demand in microelectronics and optoelectronic devices, such as wafers and touch screen glass processing industries.  

At present, UA pressure sensitive adhesive (PSA) PSA is prepared by solution coating, drying and chemical reaction. More than 60% of the solvent will be volatilized and burned, resulting in high emission, long production process and low efficiency, and harmful chemicals such as solvent may remain in the product.  

PSA is produced by UV curing. After coating solvent-free liquid components on the substrate, it is made by UV light irradiation and photopolymerization. There is no need for hot drying, the production line is simplified, the production process is environmentally friendly, almost zero emission, and the production efficiency is greatly improved. PSA has a wide range of products, from decorative films, various protective films to engineering structural tapes, which are used in advertising boards, electronic products and high-end packaging boxes.

UV compound glue food, beverage and some biomedical products need high barrier soft packaging, and the barrier of packaging materials determines and affects the edible time. High barrier packaging material is made of plastic film, paper and metal film, which has the characteristics of high strength, good oxygen and water insulation, safety, hygiene, non-toxicity, adaptability to printing, and resistance to freezing and high temperature of 120℃.

At present, almost all the composite adhesives in the soft packaging industry are solvent-based adhesives, and the quality of the solvent is more than 70%. After coating, solvent volatilization, compounding, storage and curing, the composite film is flammable and explosive, with high emission, long production process and low efficiency, and solvent remains in the composite film.

Every holiday season when the demand for exquisite packaging is strong and the delivery is urgent, many composite packaging films are delivered without fully reacting and completely volatilizing clean solvents. Residual solvents and chemical substances that have not reacted completely may permeate and pollute food, which is one of the main reasons why there are still many medicines and food packaging materials whose health indicators are not up to standard. Although water-based adhesive has no solvent, it is slow in drying, low in production efficiency and unsatisfactory in adhesion to plastics.

Using UV adhesive instead of solvent adhesive will not only greatly improve the production efficiency of composite membrane, but also reduce the production process from several hours to one minute. UV adhesive contains no solvent, no volatilization and no harmful residue, which can ensure that the composite film can meet the health and hygiene requirements of packaging materials such as food and medicine.

When the solvent volatilizes for several hours or even dozens of hours, the construction site can't be used during this period. If the light-cured adhesive is used, there is no such problem. You can first coat the light-cured adhesive on the ground, self-level, and then irradiate it with ultraviolet light to make the surface sticky. Then, the PVC floor can be used immediately, which not only greatly shortens the construction period, but also does not volatilize the solvent and pollute the indoor air in the whole production process.

UA building adhesive safety glass is mainly made of polyvinyl butyral film, which is bonded by vacuum degassing and hot pressing. The total production time takes about ten hours. It has been a long time to produce laminated safety glass by liquid bonding with edge sealing, glue filling and storage in natural light for dozens of minutes to complete photopolymerization, but it is still a non-mainstream product at present, mainly used in the low-end safety glass market.

The reasons why liquid bonding method can't be widely accepted are mainly that the performance of UV glue is not enough and the safety is lack of reliable data. UV glue has a good growth momentum in the construction field, and it is used in kitchen windows, decoration and stained glass in shops. With the improvement of performance, UV building adhesive will have great development. In recent years, the application of PVC stone plastic floor has developed rapidly in China. The construction method is to scrape a layer of adhesive on the construction ground first, and then stick the PVC floor on it.

PVC plastic flooring adhesives can be mainly divided into three categories: water emulsion type, solvent type and reactive type. Water emulsion adhesive uses water as dispersion medium, and the product is non-toxic and has low cost. However, the water resistance is poor. Generally, after being soaked in water, the adhesion is greatly reduced, such as waterborne acrylate. Solvent-based adhesives are mainly polyvinyl acetate and neoprene adhesives. The reactive type has polyurethane series adhesives. This kind of adhesive is needed after construction.

UA electronic adhesive has been widely used in the field of electronic products, including the positioning of cable, pin sealing, the preparation of LCD panel, mobile phone buttons, etc. UV curing bonding is a necessary technical means in the manufacture of electronic products. With the thinning of electronic products and the emergence of organic optoelectronic devices and flexible display devices, there is a great demand for UV adhesives suitable for roll-to-roll process. The characteristics of high efficiency, rapidity, timeliness and controllability of UV curing will be fully revealed.

At present, the touch screen of UV optical adhesive is the largest single application of UV optical adhesive. UV optical adhesive in touch screen has three functions: bonding, increasing light transmittance and improving impact resistance, which need to meet strict performance requirements, including color, weather resistance and environmental stability, electrical performance and optical performance.

The bonding materials involved in touch screen bonding mainly include: glass, ITO conductive layer, PET, PMMA, PC, etc. When the touch screen is made of sapphire, UV glue with higher refractive index will be needed to improve the light transmittance. At present, there are liquid optical adhesives (LOCA) and solid optical adhesives (OCA) used for touch screens. The former uses a program-controlled adhesive dispenser to dispense the adhesive, covers the glass cover plate, flattens it, and cures it through the cover plate, which has the advantages of good filling and convenient sizing, but needs to be cleaned up. OCA is a double-sided PSA with no substrate, and the top and bottom are release films. When in use, the light release film is removed for bonding, and then the heavy release film is removed for bonding with the other bonding surface.

The liquid adhesive used in the previous touch screen is thermosetting, which has a long production process and low efficiency. Now it has all been converted into UV curing adhesive. At present, OCA is still produced by traditional solvent-based adhesive through coating, drying and thermal crosslinking, and there are many defects caused by long baking length and dust. Using UV curing technology will greatly improve production efficiency and reduce equipment investment and production cost.