ThreeBond Technical News Issued January 1, 2013 Two-Part Acrylic Elastic Epoxy that Cures at Room Temperature Introduction SGAs (second generation acrylic adhesives) are two-part mixture acrylic adhesives that are generally considered to cure quickly at room temperature for excellent productivity. They can also increase work efficiency and save energy by eliminating the need for UV irradiation chambers, hot air drying ovens and other curing equipment. In this document, we will introduce a two-part mixture acrylic adhesive that boasts improved durability and elasticity even after quickly curing at room temperature. Hereafter, ThreeBond is abbreviated as TB.

1. Background 1-1 Environmental Concerns In recent years, manufacturing industries such as automotive, electrical and electronic manufacturers have been required to put measures in place to prevent global warming during production processes. Manufacturing technologies are being developed intensively to promote resource and energy conservation in the ever-expanding effort to develop products that protect the global environment. In the automotive industry, development continues on hybrid (HV/PHV), electric (EV/FCV) and other environmentally friendly vehicles in an effort to reduce carbon dioxide...

Table 2 Two-Part Mixture Base Resin Properties Base Growth Reaction End Reaction I : Photoinitiator I • : Initiator Radical M: Monomer M* : Monomer Radical P : Polymer P* : Polymer Radical Fig. 3-b Radical Polymerization Reaction Mechanism

Acrylic adhesives are divided by reaction type. First-generation acrylic adhesives (FGA)11 are composed of acrylic monomer, a catalyst and elastomer, but no chemical reaction occurs between monomer and elastomer during curing. Even though the composition is almost identical, adhesive where there is a chemical reaction between monomer and polymer is called a second-generation acrylic adhesive (SGA)12. These demonstrate superior performance in various aspects, such as adhesive strength and durability. Acrylic adhesives where polymerization is initiated by exposure to UV, electromagnetic waves or...

automobiles are PM*3 motors, which use permanent magnets in the rotor. Among permanent magnets, neodymium magnets produce the largest amount of energy and are highly magnetic, making their adoption ideal for high capacity, low size motors. In addition to use in electric and hybrid automobiles, PM motors are also the main electric motor used for EPS*4 and other systems that use small motors. An epoxy, anaerobic and two-part (acrylic) adhesive that cures at room temperature are used to affix the permanent magnet to the stator. In high torque-generating medium and large electric motors that produce...

Tensile Shear Bond Strength (MPa) Here are some of the properties of TB3955, our two-part acrylic elastic epoxy that cures at room temperature. 5-1 Curing Efficiency Previous two-part room-temperature curing adhesives had excellent reaction speed, but this was also problematic because it meant a short pot life that reduced working time. Therefore, we optimized pot life for TB3955 in consideration of workability and productivity (Fig. 5). However, we also ensured that once the curing reaction starts, it accelerates rapidly to quickly reach practical strength. When cured at a 25°C room temperature,...

In TB3955, the curing reaction begins when the main agent and the curing agent are mixed in a 1:1 ratio. This product was commercially released in twin cartridges so that it can be mixed in a static mixer then applied directly to the adherent (Fig. 8). Workability is excellent because the required amount can be mixed in the appropriate ratio without weighing. Elongation rate (%) Tensile Shear Bond Strength [Fe] (MPa)

Closing TB3995, our new two-part acrylic elastic adhesive which cures at room temperature, boasts durability, flexibility and curing speeds unprecedented in previous two-part mixture adhesives. It is perfect for a wide range of fields and application development, from transportation to electronics and even public works material markets. At ThreeBond, we are constantly striving to further our technological development in order to create products that meet an ever-widening range of customer needs. <References> ThreeBond Technical News No. 44, 72 ThreeBond Co., Ltd. R&D Headquarters Development...