LORD 7545-A/D Structural Urethane Adhesive

LORD 7545-A/D structural urethane adhesive is the long-work-time grade of the LORD 7545 series, mixed 1:1 by volume and offered in off-white and black across 50ml, 200ml and 400ml cartridges. It bonds FRP, SMC and other plastics with little surface preparation, plus primed metals and dissimilar substrate combinations. The 11 to 18 minute work time is what you reach for when a panel has to be positioned, checked and adjusted before it sets, or when one mix has to cover a long seam. Mixed, it is a non-sag paste that holds position on vertical and overhead surfaces. Made in the USA.

Key Product Details

Parker does not publish a grade-specific cured elongation or service temperature figure for 7545-A/D, so neither appears above. Cured elongation across this family ranges from 70% on the faster grades to 160% on the slower ones, and A/D sits between them, so we are not going to guess. Call us if your design needs a number and we will get it from Parker.

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.

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. Stock failure across most of the CFRP and ABS conditions is the number that matters most here, because it says the joint outlasted the part. 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

• 11 to 18 minutes of work time buys you positioning. A large panel can be laid, checked against a reference edge and shifted before the adhesive sets, which is the difference between a rework and a scrap on parts that are expensive to remake.
• The cost is fixture turns. At 90 minutes to handling strength you get roughly one turn every hour and a half, against one an hour on A/C and two on A/B. Long work times need either more fixtures or a slower line.
• Purge time is 15 minutes, close to the top of the work time range. Material sitting in the mixer during a pause is on nearly the same clock as material on the part, so plan a fresh tip on any restart.
• Stock failure on CFRP at 2900 psi and on ABS across nearly every aged condition means the part gives up before the joint does. On those substrates the adhesive stops being the limiting factor in the design.
• Cold performance splits by substrate. CFRP and ABS lose shear at -40°F while e-coated steel climbs to 3300 psi, so a cross-bonded plastic-to-metal joint gets stiffer and less forgiving in winter service. Design for the plastic side.
• Shear drops roughly 60% at 150°F, expected for a urethane. Sustained heat above the low 200s belongs on an epoxy.
• At 230,000 to 650,000 cP the curative is a heavy paste. The mixed bead stays put on vertical and overhead work instead of slumping out of the joint, which matters more on A/D because the bead sits unsupported longer before it sets.
• 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

• Large panel bonding where the part has to be positioned and adjusted
• Long continuous bond lines run off a single mix
• Sidewall, roof and front panel bonding on truck and trailer bodies
• Service body and work truck panel lamination
• Structural bonding of FRP and SMC panels, covers and enclosures
• Cross bonding plastics and composites to primed, painted or e-coated metal
• Marine and recreational vehicle composite panel bonding
• Multi-joint assemblies where several parts are set from one cartridge load

How to Dispense LORD 7545-A/D

A longer work time changes the failure mode. You are less likely to run out of time mid-bead and more likely to disturb a joint that has not set yet. Fixture the part and leave it alone. Parker’s instruction is 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 that cartridge and pull the end caps. Level the plungers by expelling a little material with no mixer installed, until both sides dispense evenly.
• Fit the right static mixer for the size. Parker calls for at least 20 elements on a 50ml cartridge and at least 24 elements on a 200ml or 400ml. Purge a mixer’s length to waste before the first bead.
• Lay the bead, mate the parts and clamp inside the 11 to 18 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 90 minutes at 75°F, then handle. Full strength is 24 hours. Cure can be accelerated with modest heat, up to 250°F (121°C), which is worth considering if 90 minutes of fixture time 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.

Choosing Color and Size

Color is cosmetic. Pick black when the joint stays visible and unpainted against a dark part, off-white when it will be painted or hidden. One thing to note on A/D: black covers all three cartridge sizes while off-white is offered in 200ml only. If you need off-white and more material than a 200ml holds, you are running multiple cartridges, and if you need off-white in a small package, look at 7545-A/C in 50ml instead.

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 actually takes.

A/D and A/B are the only two grades in the family offered in both colors. If you need a dark bond line, those are your options, plus A/G if 1.5 minutes is enough time.

Available Sizes and Part Numbers

Dispensing Equipment

Each cartridge size takes its own gun. The mixers below meet Parker’s element minimums, 20 on the 50ml and 24 on the 200ml and 400ml.

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/D used for?

LORD 7545-A/D 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 long-work-time grade of the 7545 family, used on large panel work and long bond lines across truck and trailer bodies, service vehicles, marine and composite assembly. Urethane adhesive, polyurethane adhesive and PU adhesive all describe the same chemistry.

Why choose A/D over the faster grades?

Because you need time to position the part. 11 to 18 minutes lets you lay a large panel, check it against a reference and shift it before the adhesive sets. The trade is fixture time: 90 minutes to handling strength against 60 on A/C and 30 on A/B, so a fixture turns roughly every hour and a half. If your parts are small and your bottleneck is fixtures, a faster grade is the better choice.

Does LORD 7545-A/D come in black?

Yes, and black covers all three cartridge sizes. Off-white is offered in 200ml only. Both colors run the same 11 to 18 minute work time and the same 90 minute handling strength, so the choice is cosmetic. Pick black for a visible unpainted joint on a dark part.

Which cartridge size should I order?

Match the size to the bead length. A 1/4 in bead gets you roughly 5 ft from a 50ml, 20.7 ft from a 200ml and 41.4 ft from a 400ml, minus a mixer’s length of purge. Note the color constraint: 50ml and 400ml are black only, and off-white comes in 200ml. Each size takes a different gun.

What gun and mixing tip does each cartridge need?

A 1:1 gun matched to the cartridge size, with a static mixer of at least 20 elements on the 50ml and at least 24 on the 200ml and 400ml. Those minimums come from Parker’s 7545 series application notes, and under-mixing is the most common cause of a bead that never fully cures. The dispensing table above lists what we stock.

What surface prep does LORD 7545-A/D 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.

How strong is a LORD 7545 bond?

Strong enough that the substrate usually fails first on composites and plastics. Parker’s testing shows stock failure on CFRP at 2900 psi lap shear at room temperature and on ABS across almost every aged condition, meaning the test coupon broke before the bond did. On e-coated steel the failure mode is cohesive at 2350 psi. The full table is above, including salt spray, humidity and water immersion aging.

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].