UV curing adhesive composition (a)

UV curing adhesive is composed of basic resin, reactive monomer, photoinitiator and other components, and is composed of stabilizer crosslinking agent, coupling agent and other additives. Under the irradiation of Uv light of a suitable wavelength, the photoinitiator rapidly generates a free agent or ion, thereby initiating the polymerization and cross-linking of the base resin and the reactive monomer into a network structure, thereby achieving the adhesion of the bonding material.

1.1 Base resin

1.1.1 Unsaturated Polyacetal Resin

Unsaturated polyester resins are light-curing resins that were used earlier. It is composed of unsaturated dibasic acid (or acid ligand) mixed with partially saturated dibasic acid (or acid ligand) reacted with glycol under the action of initiator to form linear polyester. In its molecular structure In the presence of an unsaturated vinyl monomer, if an active vinyl monomer is copolymerized with such an unsaturated vinyl monomer, the cross-linked curing forms a bulk structure, and the adhesive produced from this resin is cured due to the curing process. The volume shrinkage is large, the internal stress of the glued joint is large, the microcracks inside the gel layer are easy to occur, and the adhesive force is reduced; at the same time, since the polymer chain contains ester bonds, the acid and alkali are easily hydrolyzed, so the medium resistance is high. It is poor in water resistance, easy to deform under high temperature and humidity, and its curing speed is slower, so its overall performance is poor, and most of it is used as a non-structural adhesive. By reducing the content of unsaturated bonds, monomers with low polymerization shrinkage are used. , The addition of inorganic fillers, thermoplastic polymers, etc., can improve its overall performance. Its advantages are its low price and its use in wood decoration. On the other hand, due to the variety of synthetic raw materials, From soft to very hard resin, only the addition of the monomer can be less low viscosity, easy to operate so the European market has further an amount representing 24% of the total amount of the photocurable resin.

1.1.2 Poly Acrylic Acid Vinegar

It is prepared by the condensation of alkyd acid. The variety of polyols and polybasic acids can be changed. The molar ratio of polyol, polybasic acid and (meth)acrylic acid can be adjusted to obtain adhesives with different properties. The general formula for polyester acrylate synthesis is:

In general, the polyacrylic acrylate resin has a low viscosity and good compatibility with other resins, but has a high curing shrinkage ratio. Therefore, when it is a molded article, the size of the molded article is not stable, and it is easily deformed due to stress. . There are reports of using this kind of glue for DVD discs, and the adhesive performance is good.

1.1.3 epoxy acrylate

It is obtained from the epoxy compound and (meth)acrylic acid or acrylic acid containing an OH. Among them, epoxy compounds or epoxy resins commonly used include bisphenol A epoxy resin, hexahydrophthalic acid epoxy resin, and aliphatic epoxy resin. It is characterized by an OH group on the p-position of the acrylic group, so the viscosity is higher. The molecule contains a polar group such as a trans group, an ether group, and an ester group, so that a strong interaction force is generated between the resin molecule and the adherent molecule, and the adhesive property is excellent. It is superior to the acrylate resin in terms of electrical properties and heat resistance, and the molecular weight can be arbitrarily adjusted. It is very popular due to its strong adhesion to epoxy and good photocuring activity. The bisphenol A epoxy resin acrylate cured product has a high surface hardness and good chemical resistance, but has a large internal stress and is brittle. In recent years, there have been many reports on the improvement of brittleness 1401. The use of a terminal fluorene polyether-toughened EA resin resulted in an increase in the toughness of the resin by the use of a terminal fluorene polyether-modified epoxy acrylate resin.

1.1.4 Polyurethane Acrylic Vinegar

Polyurethane acrylates are made by reacting polyisocyanates, polyols, and acrylic light groups. Due to the proper combination of rigid polyisocyanates and flexible polyether segments, resins of different properties can be obtained. Its products can be very hard or elastomeric or even very soft. Polyurethane acrylate resin combines the flexibility (especially low-temperature toughness), wear resistance, aging resistance and high tear strength of acrylic polyurethane with good weather resistance and excellent optical properties. The general reaction for synthesis is:

1.1.5 Polythiol-polyene system The resin is actually composed of polythiol compounds and polyallyl compounds. Commonly used polythiol compounds are:

The equivalent ratio of -SH, or the number of functional groups in a polyvalent olefin and a polythiol molecule can give various forms of cured products ranging from elastomers to resins. When a polycarboxylic acid and allyl alcohol are reacted to produce esters, esters of unsaturated carboxylic acids and polyhydric alcohols and other compounds containing ester bonds such as polyenes and polythiols are used as the main component of the photocurable resin of the thiol-polyene system. When in humid conditions, the cured product is easily hydrolyzed, resulting in a decrease in adhesive strength: while triallyl isocyanurate is used and

As a photo-curable composition, a cured product that is soft, elastic, transparent, and moisture-resistant can be obtained after curing. This system is not inhibited by the oxygen in the air, and the curing shrinkage is small, and multi-use communication devices, optical device assembly, and optical fiber bonding are used.