ThreeBond Technical News Published on April 1, 2009 NEW PRODUCTS ThreeBond 7700 Gold Label series Introduction ________________________________________________ The advent of instant adhesive dates back to 1949, when Goodrich Co. of the US discovered alpha-cyanoacrylate synthesis method. Since 1959, when the world’s first instant adhesive “Eastman 910” appeared in the market, practical applications are going on around the world and improvements on cyanoacrylate adhesive are under way night and day seeking for higher functionality. Instant adhesive means an adhesive which can stick adherends in seconds, as understood by the name. It is one-part non-solvent and can be used at ordinary temperature without any emission of environmental burdens, whose pro-environmental nature is widely supported. However, it has more than a few weak points to overcome as an adhesive and many trials have been made for better cyanoacrylate monomer synthesis method, additive compositions, etc. ThreeBond started production of instant adhesive in 1969 and placed various products on the market known as “ThreeBond 1700” series with different features. In 2006, we also launched “ThreeBond 7780 Gold Label” series, the ultra-fast curing instant adhesives focusing on “INSTANT”, the raison d'etre of the products. In this issue, we introduce two products of “ThreeBond 7700 Gold Label” series, developed by ThreeBond to realize high peeling- and impact-resistance and greater adhesion capabilities for difficult adherends, which were weak points of conventional instant adhesives.

1 Reaction mechanism of instant adhesive The principal component of instant adhesive is alpha-cyanoacrylate, which has strong electrophilic groups such as cyano group, carbonyl group, etc. in its molecules, causing great charge imbalance to keep polarity in the molecules. Therefore base component such as moisture in the air works as nucleophilic agent to proceed to anionic polymerization as shown in Figure-1. Instant adhesiveness by instant adhesives comes from its extremely sensitive, momentarily progressing reaction to anionic polymerization. Nu-: nucleophilic agent - water on adherend surface,...

3 Ultrahigh peeling- and impact-resistant instant adhesive “ThreeBond 7737 / 7738” 3-1. Outline To overcome above mentioned weak points of less impact-, peeling-resistance, ThreeBond 7737 / 7738 have been developed for ultrahigh peeling-and impact-resistance, which has been realized by adding and alloying a special toughening component (elastomer) for ethyl-alpha-cyanoacrylate, the main component of instant adhesive. These adhesives also have high adhesion under high heat and heatcycle environment. (Hereafter ThreeBond 7737 / 7738 are shown TB7737 / 7738.) 3-2. Properties and features Basic properties...

Impact resisting adhesion strength was tested for 2 blocks of iron stuck by the surface of 3 cm2 under 25°C, 50%RH. The strength was measured by Charpy impact test after 24 hours’ curing of adhesion under the same environment. Heat resisting adhesion was tested for two iron plates stuck under 25°C, 50%RH. The strength was measured after 24 hours’ curing of adhesion under the same environment for lap shear strength by 2 hours’ exposure at various temperatures. Thermal cycle resistance was tested for two iron test specimens stuck under 25°C, 50%RH. The strength was measured after 72 hours’ curing...

Table-4. Properties and general characteristics of TB7797 Note: * in the table indicates material failure of adherends. 4. Exclusive multi-primer "ThreeBond 7797” for instant adhesives 4-1. About primers High-polymer materials such as polypropylene, polyethylene, polyacetal, polytetrafluoroethylene (teflon®), silicone rubber are very commonly used for consumer and industrial uses. However these materials are known difficult to adhere generally, which have required very much effort to solve the problem of insufficient adhesion when stuck with usual adhesives. The main characteristics causing the...

As for chemical resistance, lap shear strength was measured back in ordinary temperature after 250 hours’ immersion in various chemicals. Table-7. Lap shear strength after immersion in various chemicals Adherends Note: * in the table indicates material failure of adherends. Note: * in the table indicates material failure of adherends. Note: * in the table indicates material failure of adherends. ** in the table indicates material failure by swelling of silicone rubber itself. Table-5 shows high lap shear strength onset for plastics hard to bond such as polyethylene. As for exposure test, lap...

As seen above, TB7797 is a multi-primer which dramatically improves adhesion for various difficult adherends, and delivers onset of stable adhesion under exposure environment by heat and chemicals. Main features of TB7797 are: (1) Far improved adhesion for difficult adherends (2) Quick drying and good workability (3) Brush, absorbent cotton, cotton swab, etc. can be used for easy application (4) Usable for all ThreeBond instant adhesive series (TB1700 and 7700 series) 4-3. Applications TB7797 is an exclusive primer specialized in instant adhesive. It is recommended to be used as pretreatment...

Conclusion It has been 60 years since the development and penetration of alpha-cyanoacrylate adhesive and a wide variety of products has been delivered until now through repeated improvements by many researchers. They have advantages of one-part and non-solvent, and instant curing, however, they also have disadvantages of blooming, less heat-resistant and less impact-resistant; the latter having been big issues for ages to overcome. The two products introduced here are supposed to have shown the possibilities of instant adhesives for multifaceted applications by not only overcoming disadvantages...