December 15, 2023 Longchang Chemical

What are the four main components of UV adhesive and the characteristics use?

UV adhesive, also known as ultraviolet light curing adhesive, shadowless adhesive, photosensitive adhesive, refers to the photoinitiator in the ultraviolet light irradiation to produce active radicals or cations, thereby triggering the polymerization of unsaturated monomers, cross-linking and other reactions, and rapid curing and become.
UV curing adhesive has the following characteristics:
1, short curing time, usually within 1min curing.
2, curing conditions require low, room temperature can be cured;
3, green, low volatile raw materials.
4, good optical properties, good weather resistance, high transparency.
5, high hardness, wear resistance and flame retardant. Due to these unique advantages, ultraviolet curing adhesives (hereinafter referred to as UV adhesives) have been rapidly popularized and widely used.
In various industrial fields, such as the manufacture of optical products manufacturing and other electronic components, UV adhesives are widely used; in daily necessities, such as glass furniture manufacturing assembly, jewelry and other jewelry assembly industry, are also commonly in the use of UV adhesives. In recent years, UV adhesives have made good progress in research and application, and new breakthroughs have been made in raw material selection and structural improvement.
UV adhesive composition and application:
Usually, UV curable adhesive consists of oligomers, reactive monomers, photoinitiators, additives, etc. Generally speaking, the ratio of oligomers is 20% to 50%, monomers are 5% to 60%, photoinitiators are 1% to 10%, additives are 1% to 10%, the ratio varies according to the substances to be produced.

Ingredients of UV adhesive (a): zwitterionics

Oligomers, also known as oligomers and prepolymers, are unsaturated resins with double bonds that can be light-cured. It accounts for the largest proportion of UV gels, generally 20% to 50%, and is the key property of the adhesive layer.
Oligomers used in UV gels mainly include epoxy acrylates, urethane acrylates, unsaturated polyesters, etc., of which epoxy acrylates and urethane acrylates (abbreviated as PUA) contain abundant varieties and raw materials. The dosage is very large because of the high activity and moderate price. Acrylates are still the most commonly used oligomers in the light-curing field, accounting for about 82% of the total market.
Currently, oligomers are moving towards high activity, high performance, low viscosity and low price. In order to obtain fast curing and low viscosity prepolymer, it is necessary to consider the curing rate of the cured film, viscosity and physical and chemical factors.

UV adhesive composition (2): reactive diluent

Reactive diluent refers to the degree of unsaturation or functional groups of various monomers that can be polymerized to participate in the light-curing reaction, and dilute and adjust the viscosity of light-curing oligomers, which is conducive to coating. Reactive diluents can carry out the light curing reaction, reducing the volatilization of UV gel organic matter, with good environmental performance. Reactive diluents help to improve the tensile strength of the cured film. The heat resistance of the cured film increases with the increase of monomer functionality; the studied system has excellent adhesion to inorganic glass.

Ingredients of UV adhesive (III): Photoinitiators

Photoinitiators, also known as photosensitizers, generate free radicals by absorbing ultraviolet light, which triggers the polymerization and cross-linking of oligomers and reactive diluents, thus curing the film. Photoinitiators mainly include free radical photoinitiators and cationic photoinitiators.2 Free radical photoinitiators are the main system for current UV gels, but they have the disadvantages of oxygen inhibition and difficulty in curing three-dimensional objects. Among them, acyl phosphine oxide has good comprehensive performance. Czech et al. The effects of photoinitiators benzophenone derivatives and thioxanthenone derivatives on PSA properties were investigated. It was found that the adhesive strength was:UV-curable acrylate adhesive increased with decreasing initiator concentration. When the initiator (w) was, 0.5%?1.0%, the peel strength of the adhesive was relatively good; when the benzophenone derivative Michelone was used as an initiator, the corresponding adhesive had good overall performance. The advantage of cationic photoinitiators is that, after the disappearance of ultraviolet light can still occur “after curing” to continue polymerization, making it difficult to reach the part of the light completely cured. Curing. Compared with free radical photoinitiators, cationic photoinitiators have the unique advantages of small shrinkage volume, no oxygen inhibition and sufficient curing; however, their light curing speed is slow, low variety and high price. Great impact on the environment.

UV glue ingredients (four): additives

For UV glue, usually need to add a variety of additives to meet the use of requirements, such as pigments, wetting and dispersing agents, polymerization blocking agents. The effect of various additives is significant, which not only can significantly improve the performance of UV, but also expand the scope of application and reduce costs.
Inorganic nanomaterials have enhanced toughening properties. Adding nano-SiO2 to UV gels greatly improves the bonding performance and sealing effect. Hao Haifeng selected CYA-150 nanosilica from Wuxi Jindinglong Chemical Co. When the mass fraction is 2%, the adhesive strength of the adhesive can be significantly improved.

Application of UV adhesive

With the development of UV curing adhesive, it has a wide range of applications and development prospects in the field of chemical instruments, fine chemicals, 3D printing technology and other fields.
In terms of chemical instruments, UV adhesive is widely used as instrument bonding agent and safety glass bonding. For example, a variety of chemical instruments, valves, used as physical therapy electrodes, light-curing guide point pressure-sensitive adhesive, UV photosensitive tape and repair with pressure-sensitive adhesive, multi-directional joints and other parts of the adhesive are a large number of UV adhesive. In the safety glass, UV adhesive only a few seconds or minutes to complete the bonding process.
In the field of fine chemicals, there are more and more UV adhesive used in nail care. Due to the UV adhesive stability, short curing time, poor foaming, good leveling, non-toxic and environmentally friendly, the production of UV nail polish adhesive will have a broader market. In terms of 3D printing technology, SLA – three-dimensional light-curing molding technology is widely used UV adhesive, mainly using liquid photosensitive resin, so that the resulting three-dimensional material rapid prototyping, high precision, smooth and detailed surface of the object. In the field of some chemical materials, UV adhesive has been successfully applied and mature. In the chemical packaging printing, UV adhesive has become an important printing material for high-grade tobacco, alcohol, health products, cosmetics and food packaging.

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