Nanosilica Filled Adhesives Excel in High Performance Applications

Master Bond has been at the forefront of developing novel nanosilica filled epoxy formulations. These systems are designed to augment performance and processing properties over commonly used epoxy filled products containing calcium carbonate, sand, mica etc. Since numerous considerations are necessary in selecting the proper compound for a specific use, the degree of improvement provided by nanosilica filled compositions need to be carefully evaluated and compared with different conventional types of epoxy filled compositions. Additionally, the size, shape, and concentration of the filler will play an essential role in determining key parameters such as viscosity, flow, aging characteristics, strength, shrinkage, hardness, and exotherm of these polymers.

Select nanosilica filled systems have been shown to offer improved fracture toughness, thermal stability, decrease in coefficient of thermal expansion, superior dimensional stability, and enhanced wear/abrasion resistance. Among the most significant technical advances has been incorporating agglomerate-free nano-silica particles in UV/visible light curing Master Bond polymers. Utilized for structural bonding, sealing, coating, and encapsulation, these unique products require no mixing and cure in thin layers with a strong light source in as little as 10-15 seconds. UV22 and UV22DC80-1Med possess superb optical clarity, minimum shrinkage upon cure, contain no solvents or diluents, and exhibit high dimensional stability, physical strength properties, and superior electrical insulation. These cationic type, UV curing systems are serviceable from -80°F to +350°F.

UV curable nanosilica filled compounds

Master Bond UV22 has a viscosity of 2,000-6,000 cps, a low coefficient of thermal expansion and when post cured for 30-60 minutes at 125°C has a T_g about 135-140°C. It also has been successfully tested for 1,000 hours at 85°C/85%RH. In contrast, UV22DC80-10F is a member of the same family of products, and has a higher, thixotropic viscosity of around 8,000-12,000 cps. This compound has a dual cure mechanism allowing it to cure in “shadowed out” areas at 80°C. It will cure up to 0.050 inches thick and can be used for small encapsulations. UV22DC80-10F also can be post cured with heat to increase its T_g to 130-135°C. These nanosilica filled compositions are noted for their impressive abrasion resistance characteristics.

UV15-7NS has outstanding durability, splendid dielectric properties, and first class thermal cycling capability. This nanosilica filled product has very low shrinkage, magnificent dimensional stability, admirable light transmission, and adheres well to glass, metals, and plastics such as polycarbonates, acrylics, and polyester. It has a Shore D hardness of >70 and a refractive index of 1.55.

LED curable nanosilica filled adhesives

Master Bond LED405Med cures tack free upon exposure to a 405 nm wavelength light source. It meets the ISO 10993-5 specifications for non-cytotoxicity. This flowable system is intrinsically safer than UV light polymerization. Among its many benefits is its ability to bond thermally sensitive parts, adhesion to tinted, UV blocked substrates, rapid cures, consistent long-term durability, scratch/wear resistant characteristics, and low processing costs.

Nanosilica filled epoxy systems

Two part epoxy compositions containing nanosilica fillers have made progress in resolving specific application requirements for the assembly of critical components. Master Bond EP30NS has a convenient 4 to 1 mix ratio by weight and a working life of 20-30 minutes for a 100 gram batch. Rigid curing, EP30NS has a moderate viscosity with good flow. It passes ASTM E-595 (NASA low outgassing certification) and offers superb abrasion resistance. Tested for abrasion resistance per ASTM D4060-14, CS-17 wheel for 1,000 cycles, its weight loss was just 18.3 mg. High strength EP30NS is a top notch electrical insulator, and well suited for smaller pottings.

Optically clear EP114 has an ultra low viscosity high thermal stability, a long open time and a superlative physical strength profile. Service temperature range is from -100°F to +450°F. EP114 has a 100 to 80 mix ratio by weight, excellent dielectric characteristics and a Shore D hardness of 80-90. Compressive strength is an extraordinary at around 24,000-26,000 psi. ASTM D4060-14 Taber Abrasion testing results show a loss of only 5.3 mg after 1,000 cycles. This compound has also been successfully tested for 1,000 hours at 85°C/85%RH. This material’s unique blend of product properties make it highly desirable for the assembly of electronic, optical, electro-optic, aerospace, special OEM parts.