LORD 7545-A/E Structural Urethane Adhesive

LORD 7545-A/E structural urethane adhesive is the flexible, long-work-time grade of the LORD 7545 series, mixed 1:1 by volume and offered in a 200ml cartridge. It bonds FRP, SMC and other plastics with little surface preparation, plus primed metals and dissimilar substrate combinations. Two things set it apart from the faster grades: 22 to 38 minutes of work time, and a cured elongation of 160% against 70% on A/B, A/C and A/G. That second number is the reason to specify it, because a bond line that stretches more than twice as far absorbs differential movement that would crack a stiffer adhesive. Mixed, it is an off-white non-sag paste. Made in the USA.

Key Product Details

Why 160% Elongation Matters

Most of the 7545 family cures at 70% elongation. A/E and A/F are the two exceptions, at 160% and 145%. On a joint between two materials that expand at different rates, that difference decides whether the bond line flexes or fractures.

An FRP panel bonded to a steel frame is the standard case. Across a summer-to-winter swing the two substrates move different amounts, and every cycle works the bond line. A 70% elongation adhesive handles that on a short joint. On a long seam, where accumulated differential movement is larger, the extra stretch is what keeps the joint intact over years rather than seasons. Same logic applies to any assembly seeing vibration or repeated impact, where a stiffer bond line transmits the load into the substrate instead of absorbing it.

The trade is cure speed, and it is a real one. 2 to 3 hours to handling strength against 30 minutes on A/B. If your parts are short, rigid and dimensionally stable, the faster grades give you the same bond strength without tying up a fixture for an afternoon.

Cured Properties

Parker publishes the following cured properties for the LORD 7545 system. The technical data sheet does not break them out by individual curative, so treat them as series-level and test your own joint before production. Elongation is the exception and appears grade-specific in the table above.

Bond Performance by Substrate

Lap shear in psi, with failure mode in parentheses. SF is stock failure, meaning the substrate broke before the bond did. COH is cohesive failure, the adhesive itself split. ADH is adhesive failure, the bond released from the surface. Parker publishes this data for the LORD 7545 system without breaking it out by curative.

Test specimens: CFRP was 2×2 twill in an epoxy resin matrix, 3 mm thick. ABS and PC/ABS were both 5 mm thick. E-coated steel was 1008 steel, 8 mm thick, coated with PPG E6060C. Your substrate, joint geometry and surface prep will move these numbers, so run your own bond trial.

Performance in Production

• 160% elongation is more than double the faster grades. On a plastic-to-metal seam that cycles through a temperature swing, the bond line moves with the parts rather than fighting them.
• 22 to 38 minutes of work time covers long seams and multi-part assemblies off one mix, with room to position and adjust before anything sets.
• Fixture time is the cost. 2 to 3 hours to handling strength means one turn per shift on a single fixture, against two an hour on A/B. Either budget more fixtures or use modest heat, up to 250°F (121°C), to accelerate.
• Purge time is 30 minutes, inside the work time range. That is unusually forgiving for this family and means a pause mid-job is less likely to cost you a mixer.
• Stock failure on CFRP at 2900 psi and on ABS across nearly every aged condition means the part gives up before the joint does. The slower cure costs nothing in ultimate strength.
• Cold performance splits by substrate. CFRP and ABS lose shear at -40°F while e-coated steel climbs to 3300 psi. The higher elongation helps most here, since a cold joint is also a stiffer joint.
• At 230,000 to 650,000 cP the curative is a heavy paste, so the bead holds position on vertical and overhead work. That matters more on A/E than on the fast grades, because the bead sits unsupported for hours.
• 7545-A resin is moisture sensitive. Keep cartridges in the Mylar bag with the desiccant and leave the used mixer in place on a partial as a plug, or the next bead cures short.

Common Applications

• Cross bonding plastics and composites to primed, painted or e-coated metal where thermal expansion differs
• Long seams that accumulate differential movement across the joint
• Assemblies seeing vibration, road shock or repeated impact
• Sidewall, roof and panel bonding on truck, trailer and service bodies
• Marine and recreational vehicle composite panel bonding
• Large panels that need positioning time before the adhesive sets
• Outdoor assemblies cycling through seasonal temperature swings
• Multi-joint assemblies where several parts are set from one cartridge load

How to Dispense LORD 7545-A/E

The long work time changes what goes wrong. You are unlikely to run out of time and quite likely to disturb a joint that has not set. Fixture the part and leave it for the full 2 to 3 hours. Parker’s instruction is still to discard the part if working time is exceeded, because a bead that has begun to skin will not wet the mating surface.

• Prep both surfaces. Plastics and composites get a dry rag wipe or a solvent-dampened rag to pull loose debris and processing fluids. Metals get primed, painted or grit blasted, then solvent washed.
• Load the cartridge in a 1:1 gun sized for 200ml side by side cartridges and pull the end caps. Level the plungers by expelling a little material with no mixer installed, until both sides dispense evenly.
• Fit a static mixer with at least 24 elements, Parker’s minimum for 200 mL cartridge dispense. Purge a mixer’s length to waste before the first bead.
• Lay the bead, mate the parts and clamp inside the 22 to 38 minute work time. Target a 0.010 to 0.040 in bondline. Larger gaps can be filled where mating surfaces are irregular.
• Hold the part fixtured 2 to 3 hours at 75°F, then handle. Full strength is 24 hours. Modest heat up to 250°F (121°C) will shorten the fixture window if it is holding up the line.
• Clean tools with acetone or MEK before cure. Do not use alcohol. Cured adhesive softens at 300°F (149°C) and above if parts have to come apart.

Substrates the process runs on: FRP, GRP, SMC, carbon fiber, ABS, polycarbonate, PC/ABS blends, other engineered plastics, HDU urethane foam, wood, and primed, painted, powder-coated or e-coated metals. Glass, non-porous ceramic and stone need LORD AP-134 first. Vulcanized rubber and elastomers need LORD 7701. TPE and TPO need LORD 459X. Bare aluminum and bare steel are not urethane substrates, so prime them or move to an acrylic.

LORD 7545 Series Grades Compared

Every grade runs the same 7545-A resin at the same 1:1 volume ratio. The curative letter changes speed, mixed color and cured elasticity, not the chemistry. Parker states the full range of work times all provide the same bond strength, so pick by how long your assembly takes and how much the joint has to move.

A/E is the most elastic grade in the family. A/F is close at 145% and gives you nearly an hour of work time, so if you need both flexibility and a longer window, compare the two. Everything from A/D down cures roughly half as stretchy.

Available Size and Part Number

The 200ml cartridge is the only size currently offered in this grade. At a 1/8 in bead it runs about 82.5 ft and at 3/8 in about 9.3 ft, minus a mixer’s length of purge. If you need more material per cartridge, 7545-A/F cures at 145% elongation and is worth comparing, or call us and we will look at what fits.

Dispensing Equipment

• Newborn VR200XSP dispensing gun, 1:1 for 200ml side by side cartridges
• Medmix MCQ 08-24T static mixer, 24 elements, which meets Parker’s minimum for this size

Related Products

Surface modifiers, used when the substrate needs priming before bonding:

• LORD AP-134 adhesion enhancer for glass, non-porous ceramic, stone and concrete
• LORD 459X adhesion enhancer for TPE and TPO
• LORD 7701 surface treatment for vulcanized rubber and elastomers

Frequently Asked Questions

What is LORD 7545-A/E used for?

LORD 7545-A/E is a two-part structural urethane adhesive used to bond FRP, SMC and other plastics with minimal surface preparation, plus primed metals and dissimilar substrate combinations. It is the most elastic grade in the 7545 family at 160% elongation, which makes it the choice for joints between materials that expand at different rates. Urethane adhesive, polyurethane adhesive and PU adhesive all describe the same chemistry.

Why choose A/E over a faster grade?

Two reasons. 160% cured elongation against 70% on A/B, A/C and A/G, which lets the bond line absorb differential movement instead of fracturing. And 22 to 38 minutes of work time for long seams and multi-part assemblies. The trade is 2 to 3 hours to handling strength, so a fixture is tied up far longer.

What size does LORD 7545-A/E come in?

The 200ml cartridge, part number 3003917, which is the only size currently offered in this grade. It runs about 20.7 linear feet at a 1/4 in bead. If you need a larger cartridge, 7545-A/F cures at 145% elongation with a 45 to 65 minute work time and is the closest alternative.

What color is LORD 7545-A/E?

Off-white. The 7545-A resin is a brown paste and the 7545-E curative is off-white. A/E is not offered with a black curative. For a visible unpainted bond line on a dark part, look at 7545-A/B or 7545-A/D in black, though both cure at lower elongation.

What gun and mixing tip does the 200ml need?

A 1:1 gun built for 200ml side by side cartridges with a static mixer of at least 24 elements. We stock the Newborn VR200XSP gun and the Medmix MCQ 08-24T mixer. Under-mixing is the most common cause of a bead that never fully cures, and on a grade with a 2 to 3 hour fixture window you will not find out until the fixture comes off.

How long until I can handle the part?

2 to 3 hours at 75°F, with full cure at 24 hours. That is the longest fixture window in the family short of A/F. Modest heat up to 250°F (121°C) will shorten it if the wait is holding up the line, and a cooler shop will lengthen it.

What surface prep does LORD 7545-A/E need?

Plastics need a dry rag wipe or a solvent-dampened rag to remove loose debris and processing fluids. Metals should be primed or grit blasted and then solvent washed for optimum bond performance. Glass, non-porous ceramic and stone need LORD AP-134 first, vulcanized rubber needs LORD 7701, and TPE and TPO need LORD 459X. Parker notes plasma treatment can help on hard-to-bond materials in special cases.

What is the shelf life, and how should cartridges be stored?

8 months from date of manufacture in the original unopened container stored at 65 to 85°F (18 to 30°C). The resin is moisture sensitive, so keep cartridges in the Mylar bag with the desiccant until you need them, and protect a partial by leaving the used mixer in place as a seal. Run inventory first in, first out.

Questions on fit for your bonding application? Call (800) 220-1966 or email [email protected].