Tag Archives: solvent wiping
Manufacturers often encounter a similar puzzle, when cleaning invisible contaminants from a surface, how do you know when the surface is clean; how clean is clean enough? This is a common question that manufacturers ask when preparing their surfaces for bonding, coating, sealing, printing or painting. Until now, there hasn’t been an objective and reliable way to answer this question. Successfully cleaning a surface directly correlates to the adhesive ability of the surface. In order to get something to stick reliably the surface must be clean. How we define that parameter is different for a variety of materials.
For example, you clean your car differently than you clean your dishes. Why? Because a car rides on the road through rain, smog, dirt, maybe mud, and the other is a vehicle for your food.
At BTG Labs, our answer to the “clean enough” question is, “Depends on what you’re doing.” There are dozens of critical surface preparation processes that exist for a number of different applications. A handful include:
- Flame treatment on polypropylene bumpers prior to painting
- Plasma treatment on PET catheters prior to coating
- Hand sanding and solvent wiping on aircraft nut plates before adhesively bonding to composite
- Grit-blasting titanium golf clubs in preparation of bonding to composite
- Corona treatment on film for packaging prior to metallization, lamination, or coating
The utilization of composites increases daily in manufacturing as more ways in which to use this advanced material are discovered. Composite is a smart material that provides a lighter weight and stronger product. This advanced material is being used in many different industries, from consumer products like bicycle frames to airplanes. Yet, because the strength is held in the fibrous matrix of the material, composites must be adhesively bonded together as traditional mechanical fasteners can break the fibers and compromise the material’s integrity.
To guarantee these bonds, BTG Labs’ Surface Analyst™ precisely, accurately, and quantifiably measures the surface’s readiness to bond. BTG Labs’ experience in the field of composites reaches back to the genesis of the Surface Analyst when the USAF turned to the company to engineer a hand-held surface energy measurement device for composite bonding of aircraft. Since then, the Surface Analyst’s composite applications continue to increase and span into many more industries.
Surface Analyst Applications Examples for Bonding, Coating, Sealing, and Painting Composites
- Aerospace: satellites, aircraft, and spacecraft
- Sports and Recreation: sporting equipment
- Automotive: structural components, drive shafts, interior parts
- Medical Device: prosthetics, repair equipment, tubing
- Marine: structural frames and components, fiber glass applications
- Renewable energy: wind turbines, fuel cells, marine turbines, power transmissions, solar panels
- Construction: architectural, fiberglass, bridges, infrastructure, housing, refurbishing
conPolymers are some of the most common base materials used in automotive parts. Polypropelenes, Polyolefins, and ABS plastics are used in dashboards, door panels, bumper fascias, liftgates, sensors, and increasingly exterior doors and fenders. A polymer is a low surface energy material that typically needs some form of surface processing prior to bonding an assembly, encapsulating a sensor, painting an interior control knob or an exterior bumper fascia. These materials also tend to show high contamination with mold releases that can be tough to remove and will essentially guarantee unsuccessful adhesion or coating.
There are a variety of surface processing methods used in the industry to help remove contamination and increase the surface energy of these polymer materials. These processes include flame treatment, plasma treatment, corona treatment, and solvent wiping. Another option is to utilize specialty paints and adhesives that tolerate lower energy substrates. There are pitfalls, however, to implementing any of these methods that manufacturers need to be aware of. Understanding the nature of these surface-critical systems is the only way to guarantee success in the final result. Control of the inputs means predictability and control of the output.
Solvent wiping and sanding procedures can greatly affect the surface energy of a substrate. To investigate the surface energy differences following different preparation procedures of an epoxy composite laminate, researchers created several different surface conditions utilizing different cleaning techniques. For this experiment, a BTG Labs Surface Analyst™ obtained measurements.
The Surface Analyst is a fast, easy, accurate and nondestructive instrument that measures the contact angle of water applied to the surface in a precise, controlled manner. This contact angle is determined by how strongly the surface energy of the substrate and the liquid deposited interact. The relationship between this contact angle and surface energy is complex, but well understood. More importantly, this relationship correlates with the adhesive strength of a paint, coating, print or adhesive to the substrate.