Seeing clearly now
More and more kinds of display screen technologies have started to shine, creating new demands for compatible adhesives. To keep pace with the growing number of display materials, Adhesives Research has introduced new ARclear optically clear adhesives. Available in both transfer and single-faced-film versions, these pressure-sensitive adhesives target a variety of flat-panel, touchscreen, and projection display components-such as polarizers, filters, back lighting, and reflective materials. The transfer adhesives include permanent, strippable, and silicone varieties. These non-birefringent adhesives typically offer haze levels under 1%, clarity above 97%, and light transmission about 95%, according to Dave Williams, business development manager. Peel adhesion varies with grade and thickness, but a 1.0-mil version of the permanent grade offers a peel strength of 30 oz/in in ASTM tests. The ARclear films, which have an optically clear adhesive on one side, come in two new varieties: 3.0-mil polyester and a 7.0-mil hard-coated film. Both offer a haze less than 2%, clarity above 97%, and light transmission better than 92%, Williams reports. Peel adhesion for the 3.0-mil film is 20 oz/in, while the hard-coated version offers 15 oz/in as well as a taber abrasion less than 9% and a 3H pencil hardness.
A cure for medical bonding problems
The latest light cure adhesives from Dymax target optical applications that also require Class VI biocompatability. These new single-component 140 Series Medical Optical Adhesives include UV- or visible-light-curing formulations as well as a fixturing grade that adds a heat cure mechanism for those times when an assembly has places where the light doesn't shine. The 140 Series covers a range of viscosities from a gel to wicking grades. Applications include fiber optic bonding and splicing, lens bond, and the attachment of glass, quartz, metal and plastic components to optical assemblies.
New version of metal bonding
ITW Devcon has introduced a revamped formulation of Metal Welder, a methacrylate-based adhesive for joining aluminum, steel, stainless, and other metals without primer. According to sales and marketing manager Chris Stevens, the new Metal Welder offers lap shear strengths in excess of 2,500 psi. Also new from Devcon are two rubber-toughened adhesives-a cyanoacrylate and a one-part epoxy.
Adhesive takes place of welding
A new Permabond adhesive kit has been developed as an alternative to the thermite welding that normally attaches corrosion-fighting electrodes to pipelines and other steel structures. These Cathodic Protection kits consist of individually packaged Neoprene covers, electrodes, alcohol swabs, a conductive epoxy to connect the electrode to the pipe, and an industrial adhesive for the Neoprene connector. The CC468 kit handles 4, 6, and 8 gauge wire, while the CC1012 kit accommodates 10 and 12 gauge.
Cut first, glue later
PreForm Adhesives, a year-old business unit of National Starch and Chemical Corporation, has developed a variety of new die-cut, roll, tape, and sheet adhesives in epoxy and thermoplastic formulations.
According to Dan Leeser, technical manager, the company can also laser cut adhesive preforms with just a one-day turnaround time.
While suitable for manual application, precut adhesives especially target robotic assembly, Leeser adds.
For structural bonding applications, the company's adhesives offer up to 6,000 psi in lap shear strength, Leeser says. The company has developed adhesive films that do more than just bond. These films also offer functional capabilities such as thermal or electrical properties.
Tapes for high temperature low energy
3M, at the National Design Engineering show, brought out new versions of its well-known VHB adhesive tapes. VHB 4611, which pairs an acrylic adhesive with an acrylic foam carrier, targets high-temperature applications with temperatures up to 450F. Previous VHB tapes topped out at around 300F. Applications include bonding metal parts prior to painting. VHB 5952, also an acrylic foam tape, bonds low-surface-energy materials like polyolefins without the need for primer. Both tapes are 0.045 inches thick.
|Properties and performance characteristics|
|VHB 4611||VHB 5952|
|Peel adhesion (stainless steel), lb/in width||18||25|
|Normal tensile (aluminum t-block), psi||90||120|
|Dynamic shear, psi||65||90|
|Temperature resistance, F Short term||450||300|
|Temperature resistance, F Long term||300||250|