HIGH CHEMICAL RESISTANT POLYURETHANE SEALANT

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 millscale and rust and mild steel treated with a suitable anticorrosive primer.

Urochem 211 is a two-component sealing compound based on a hydrophobic polyurethane resin and an isocyanate curing agent. The system crosslinks to produce a tough, durable rubber like seal. Its unique chemistry ensures that it is unaffected by high concentrations of acids, alkalis, and water-soluble salts.

Priming: For porous or friable surfaces, where severe conditions are expected, or continuous immersion is anticipated 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. After approximately 3 hours or once the primer has lost its tack, re-priming is required. Protect the primed surface from dust and dirt which could coat it and interfere with the adhesion of the sealant.

Typical applications include its use in both vertical and horizontal joints in bonded areas designed to contain chemical spills, sewerage treatment plants, sumps, laboratories, and chemical manufacturing plants.

• The minimum width and depth of a joint should be 6 by 6 mm. Horizontal joints, where possible, should be at least 12 mm and not more than 25 mm deep. The depth of the joint should never exceed its width. Except in the case of water retaining structures and where shear movement is anticipated the ratio of width to depth of 2: 1 should if possible 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 six times the maximum anticipated movement. When placing the sealant, the joint opening should be central to its maximum compression/expansion cycle.

• Mix the base thoroughly using an electric drill fitted with a suitable mixer before adding all of the activator and remixing.

• Fill the sealant into a closed barrel gun using a follower plate or small trowel. Gun 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 cure has commenced.

To ensure proper 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.

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.