Scott Bader has recently added two new Crestomer® grades to its ‘new look’ structural adhesives range: Crestomer Advantage 10 in 380 ml cartridges, with a 50% shorter fixture time of only 70 minutes compared with Advantage 30; and Crestomer 1150PA, available in 25 kg kegs (pails) and 200 kg drums for use with dispensing equipment, also with a 50% shorter fixture time of 5 hours compared with Crestomer 1152PA, which is a long established grade with Lloyds, DNV and RINA marine approvals. Both new grades are primarily aimed at structurally bonding smaller sized FRP components and improving productivity. Switching to these new grades has benefited mid-volume OEMs, such as boat and speciality vehicle builders, as well as companies providing FRP repair services, enabling de-bottlenecking and increasing capacity by being able to move assembled structures much more quickly due to the significantly shorter fixture time.
All Crestomer products are urethane acrylate technology based structural adhesives in a styrene monomer, originally developed for bonding GRP and marine ply substrates, but with suitable surface preparation they can also be used to bond aluminium and stainless steel parts. Crestomer structural adhesives have more than 40 years’ of proven use in marine, building and construction, wind energy, transport, agricultural and recreational vehicle applications. All grades are highly thixotropic and so do not sag during application on vertical surfaces, with good gap filling capabilities. In a wide variety of demanding end use applications, Crestomer adhesives provide excellent adhesion, with bond lines maintaining high toughness, fatigue and impact strength properties under load.
Depending on the number of composite components being bonded and the shop floor working time required, the two new Crestomer Advantage 10 and Crestomer 1150PA grades now available, offer a faster cycle time and higher productivity adhesive assembly option for GRP moulders. Prior to bonding, only minimal surface preparation is needed, such as removing strippable cloths (e.g. peel-ply) without lubricant contaminates, or for parts de-moulded for more than three days, lightly abrading and acetone wiping the adhesion surfaces prior to bonding is all that is needed.
Crestomer Advantage 10
The new Advantage 10 grade is now the fastest curing adhesive in Crestomer range, with only a 10 minute working time and 70 minutes fixture time. It has an opaque white colour and can be used for structural bonding and gap filling up to 15mm. Crestomer Advantage 10, like Advantage 30 (working time 30mins), is supplied pre-accelerated in a 380ml co-axial cartridge which fits most standard manual or pneumatic hand guns. The coaxial cartridge contains the 10:1 ratio Advantage catalyst, and is used with a replaceable static mixing nozzle to ensure that a fully mixed adhesive is dispensed straight from the cartridge at the point of use. The handy cartridge format and rapid fixture time is ideal for bonding by hand in confined access areas.
According to published Scott Bader technical data for Crestomer Advantage 10, the typical maximum tensile strength achieved is 20 MPa with a tensile modulus of 920 MPa and elongation of > 85% using the BS EN ISO 527-2 test method. Lap shear bond joint strengths, tested to ISO 4587, in the case of marine ply and FRP, are limited by the weaker substrates which both fail before the Crestomer adhesive. In the case of stainless steel and aluminium, adhesion failure occurs, with lap shear bond joint strengths of 12.5 MPa and 13.5 MPa respectively, typically being achieved if the recommended surface preparation guidelines are followed.
Crestomer 1150PA is purple/ brown coloured thixotropic gel, also supplied pre-accelerated as a two part adhesive system which uses a 50:1 mix ratio by volume and weight (v/w). The recommended hardener is Butanox® M50 or equivalent MEKP catalyst, added at 2% v/w. It has a working time (at 25 oC) of only 50 minutes and a fixture time of 5 hours. Mechanical properties and bond strength are not compromised, with 1150PA data sheet giving typical values of: 23-26 MPa for maximum tensile strength; 1000 MPa tensile modulus; 100% elongation at break (according to BS EN ISO 572-2).
Crestomer 1150PA can be applied by hand with a spatula or from a bulk dispensing unit with a gun, and is used for bonding and gap filling applications up to 15mm thick. The 1150PA grade is suitable, not only for bonding “green” FRP laminates, but also balsa and foam core materials, wood, and some metals. It can also be used for bonding composite diesel tanks, contour joints, and to build up damaged areas in sections of an FRP component, so is ideal for use in MRO (maintenance, repair and overhaul) applications.
Global Growth Focus
Jon Stowell, Global Head of Adhesives and Tooling for Scott Bader commented: “We are continuing to strategically focus on growing our Adhesives business globally for the long term. In addition to using our in-house R & D resources to develop new, more rapidly bonding grades of both our urethane acrylate Crestomer and primer-less MMA Crestabond® adhesives ranges, we recently also made a capital investment of over £400K to add another mixer to our adhesives production facility in the UK. The additional mixer has increased production capacity by around 50%, which is needed to cope with the continued growth in sales over the last five years, and forecasted customer order levels in 2017 and beyond.”
As part of its ongoing global growth strategy, Scott Bader is exhibiting at a number of key exhibitions later this year, including Composites Europe, Bond Expo, and UK Advanced Engineering in Europe, IBEX and CAMX in the USA, and the Shanghai International Automotive Manufacturing Technology & Material Show 2017 in China.