Sikaflex®-291

Sikaflex®-291 is a non-sag 1-component polyurethane sealant specifically developed for the marine market, which cures on exposure to atmospheric moisture. Sikaflex®-291 meets the requirements of the International Maritime Organisation (IMO).

Recommended uses

Sikaflex®-291 is a multipurpose product for the use in marine constructions. It is suitable to make elastic, vibration-resistant joint seals, and can also be used for a variety of interior sealing applications. Sikaflex®-291 bonds well to the materials commonly used in marine construction like wood, metals, metal primers and paint coatings (2-C systems), ceramic materials and plastics (GRP, etc.). Once cured, Sikaflex®-291 can easily be sanded as required. This product is suitable for experienced professional users only. Tests with actual substrates and conditions have to be performed ensuring adhesion and material compatibility.

PRODUCT BENEFITS

Bonds well to a wide variety of substrates Good ageing and weathering resistance Elastic Low odour Non-corrosive Can be over painted Can be sanded

Packaging

Cartridge 300 mL

CURE MECHANISM

Sikaflex®-291 cures by reaction with atmospheric moisture. At low temperatures the water content of the air is generally lower and the curing reaction proceeds somewhat slower (see diagram 1). Diagram: Curing speed Sikaflex®-291

CHEMICAL RESISTANCE

Sikaflex®-291 is generally resistant to fresh water, seawater, diluted acids and diluted caustic solutions; temporarily resistant to fuels, mineral oils, vegetable and animal fats and oils; not resistant to organic acids, glycolic alcohol, concentrated mineral acids and caustic solutions or solvents.

Surface Preparation

Surfaces must be clean, dry and free from grease, oil and dust. Surface treatment depends on the specific nature of the substrates and is crucial for a long lasting bond. Suggestions for surface preparation may be found on the current edition of the appropriate Sika Pre-treatment Chart for Marine Applications. Consider that these suggestions are based on experience and have in any case to be verified by tests on original substrates.

Application

Sikaflex®-291 can be applied at temperatures between 5 °C and 40 °C but changes in reactivity and application properties have to be taken into considerations. The optimum temperature for substrate and sealant is between 15 °C and 25 °C. Sikaflex®-291 can be processed with hand, pneumatic or electric driven piston guns as well as pump equipment. For advice on selecting and setting up a suitable pump system, contact the System Engineering Department of Sika Industry.

Tooling and finishing

Tooling and finishing must be carried out within the skin time of the product. It is recommended using Sika® Tooling Agent N. Other finishing agents must be tested for suitability and compatibility prior the use.

Removal

Uncured Sikaflex®-291 can be removed from tools and equipment with Sika® Remover-208 or another suitable solvent. Once cured, the material can only be removed mechanically.

Overpainting

Sikaflex®-291 can be best painted after formation of a skin. Painting could be improved by treating the joint surface with Sika® Aktivator-100 or Sika® Aktivator-205 prior to paint process. If the paint requires a baking process (> 80 °C), best performance is achieved by allowing the sealant to fully cure first. All paints have to be tested by carrying preliminary trials under manufacturing conditions. The elasticity of paints is usually lower than that of sealants. This could lead to cracking of the paint in the joint area.

Application temperature

ambient 5 °C ─ 40 °C Skin time (CQP019-1) 60 minutes A Open time (CQP526-1) 45 minutes A Curing speed (CQP049-1) (see diagram) Shrinkage (CQP014-1) 5 % Shore A hardness (CQP023-1 / ISO 48-4) 40

Shelf life

12 months B QP = Corporate Quality Procedure A) 23 °C / 50 % r. h. B) storage below 25 °C