Automotive sheet metal PU sealant (polyurethane sealant) is a single component, moisture curing elastic sealing adhesive designed specifically for body welds, sheet metal joints, and car/roof overlaps. It combines the three core advantages of sealing, waterproofing, elasticity, vibration resistance, and spray painting, and is a key material for vehicle manufacturing and maintenance.
1、 Core Features
Curing mechanism: Single component room temperature moisture curing, gradually curing upon contact with moisture in the air, no need for mixing, convenient construction.
Elasticity and strength: After curing, it has excellent elasticity (elongation ≥ 150%), resistance to vibration and tear, can absorb dynamic stress of the vehicle body, and prevent cracking and water leakage.
Broad spectrum adhesion: Strong adhesion to plastics such as steel plates, galvanized sheets, aluminum, glass, ABS/fiberglass, etc., without corrosion or pollution.
Can be polished and spray painted: After curing, it can be polished and sprayed with topcoat, without affecting the adhesion and appearance of the paint surface, suitable for sheet metal repair processes.
Construction friendly: Good thixotropy, no flow in vertical joints ≤ 30mm; Good extrusion performance, easy to scratch and modify, suitable for manual/pneumatic glue guns.
Durable and weather resistant: waterproof and dustproof, aging resistant, high and low temperature resistant (-40 ℃~+90 ℃), UV resistant, long-term use without brittleness or detachment.
2、 Typical application scenarios
Body welding seam sealing: After welding, the sheet metal seam is filled to prevent rainwater infiltration, corrosion, and enhance the rigidity of the body.
Sealing of carriage/roof/door edges: The roof and side panels, as well as the inner and outer panels of the doors, of box cars, buses, and trucks should be sealed for waterproofing and sound insulation.
Structural bonding reinforcement: Some working conditions can replace spot welding by bonding thin steel/aluminum plates, reducing weight and minimizing the risk of weld corrosion.
Repair and refurbishment: After repairing the sheet metal of the accident car, the seams are sealed, and the leaking parts of the old car are repaired.
3、 Common specifications and colors
Packaging: 310ml/400ml/600ml soft pack/hard tube, 30kg drum.
Color: white, gray, black (suitable for different body colors and concealed parts).
Typical parameters (reference): surface drying takes about 30 minutes, basic curing takes 24 hours, and complete curing takes 7 days; Tensile strength ≥ 1.8MPa, elongation ≥ 150%.
4、 Key points of construction
Surface treatment: Clean, dry, oil-free and rust free. The primer/topcoat surface needs to be polished rough to enhance adhesion.
Glue application: The glue gun applies glue at a constant speed, the glue strip is continuous without breaks, and the width/thickness is suitable for the gap (usually 5-10mm wide and 3-5mm thick).
Decoration: Scrape and shape within 10-15 minutes after applying glue to ensure smooth and neat edges.
Curing: At room temperature (23 ℃) and humidity of 50% -70%, the surface will dry for about 30 minutes, and can be lightly touched for 24 hours. The optimal strength will be achieved in 7 days; Low temperature and low humidity require extended curing time.
Spray painting: After complete curing (recommended for 7 days), polish and spray paint to avoid solvent erosion of the adhesive layer before curing.
5、 Difference from silicone adhesive
PU adhesive: can be painted, has good elasticity, high bonding strength, oil resistance, suitable for sealing body structures; The disadvantage is that curing requires moisture and is not resistant to long-term strong acids.
Silicone adhesive: has higher temperature resistance, better weather resistance, and faster curing, but cannot be sprayed with paint, has low bonding strength, and is prone to contaminating the paint surface. It is mostly used for non appearance parts (such as chassis and engine compartment).
