POLYURETHANE SEALANT

Urochem 299 is a two-component sealing compound based on a polyether polyurethane, blended with fillers and a chemical curing agent, which reacts after mixing to form a durable rubber like seal. This sealant is highly elastic and is able to withstand continuous extension and recovery. It may be used with most common building materials such as concrete, plaster, brick, and stone. It exhibits superior resistance to abrasion, ultraviolet light and ozone making it suitable for exterior use. Due to its excellent water resistance and adhesion plus resistance to biodegradation it forms the ideal material for use in sewage treatment plants.

• The minimum joint dimension should be 6 x 6 mm. Horizontal joints, where possible, should be at least 12 mm and not more than 25 mm. The depth of the joint should never exceed its width. Except in the case of water retaining structures and where shear movement is anticipated, a width to depth ratio of 2 :1 should be maintained. This ratio provides the optimum geometry to allow movement to occur within the joint without placing excessive force on the joint faces.

• Joint faces should be parallel, and the joint width should be at least four times the maximum anticipated movement. When placing the sealant, the joint opening should be central to its maximum compression/expansion cycle.

• To form a long-lasting water and weatherproof seal in both horizontal and vertical moving joints and joints which are subject to continuous cyclic movement.

• Typical applications include joints in curtain walls, floor expansion joints, drainage channels and sewage treatment plants, between precast units and to seal pipe sections.

To ensure correct movement of the joint a bond breaker must be used at the base of the joint. Where a backing material such as polyethylene foam rod is used to ensure the correct joint geometry a bond breaking tape is not required. For water retaining structures care must be taken to comply with design requirements set by the engineer.

• Fill the sealant into a closed barrel gun using a follower plate or small trowel. Gun the sealant into the joint using a continuous squeezing of the trigger to ensure a smooth continuous flow of material. Fill the joint from the bottom up and ensure that there is contact between the sealant and joint surfaces.

• To ensure contact of the sealant with the walls of the joint, the sealant should be tooled to a smooth finish using a rounded spatula. A soapy solution may be used to aid the process. Remove any masking tape applied before curing commences.

The correct preparation of the joint faces is absolutely essential to the satisfactory performance of the sealant. All surfaces should be clean, sound, and dry, and laitance or surface contamination should be removed by thorough wire brushing, grinding or grit blasting. Vacuum or blow with compressed air to ensure thorough removal of dust. Metal surfaces should be free of mill scale and rust and mild steel treated with a suitable anticorrosive primer.

Clean all tools and equipment with Urochem 901 before setting of the sealant has taken place.

Contact with skin should be avoided by wearing gloves and protective clothing. In case of eye contact wash well and obtain medical advice.

• Urochem 102 Silane Primer should be used on glass, ceramics and sound masonry and brick surfaces not subjected to water immersion.

• Refer data sheet.

• Apply a single thin coat by brush and allow to dry for at least ten minutes before application of the sealant. If sealant is not applied after three hours re-prime. For water retaining structures, porous or friable surfaces or where severe conditions are expected use Urochem 101 or Urochem 106 Epoxy Primer. Mix base and activator thoroughly and apply the mixed material with a brush to the joint faces ensuring complete coverage. Particular attention should be paid to any voids and hollows. Allow at least 30 min. for the solvent to evaporate before applying the sealant.

• If after 3 hours or the primer loses its tack, re-prime.

• Protect the primed surface from dust and dirt, which could interfere with the adhesion of the sealant.

Transfer the total quantity of activator onto the base component and mix thoroughly using a slow speed electric drill fitted with a flat blade stirrer. Scrape down the sides of the container regularly during mixing and mix until the colour is uniform and free from streaks. Thorough mixing is essential and should take 5 to 10 minutes.