What is SIKAFLEX 591 and why choose it?
SIKAFLEX 591 from Sika is a multipurpose, 1-component adhesive sealant based on Silane Terminated Polymer (STP) technology. It is designed for interior and exterior sealing and bonding in the maritime industry, above and below the waterline. Thanks to its very high colour stability, mold resistance and excellent weathering performance, it is suitable for long-lasting elastic joints on boats and marine structures, while offering a health-conscious formulation free from solvents, isocyanates, phthalates and PVC.
Main features
- Multipurpose marine adhesive sealant for elastic joints and a wide variety of sealing applications in and around boats.
- 1‑component, moisture‑curing STP technology that cures on exposure to atmospheric moisture.
- Very high colour stability and mold resistance, even under harsh maritime conditions.
- Excellent weathering resistance, suitable for interior and exterior joints, above and below the waterline.
- Good non‑sag properties for clean application on vertical and overhead joints.
- Good adhesion to many substrates commonly used in the marine industry with minimal surface preparation.
- Health-conscious formulation: solvent‑free, isocyanate‑free, phthalate‑free and PVC‑free.
- Certified according to IMO (tested to IMO Res. MSC.307(88) – 2010 FTP Code Annex 1, Part 5, Annex 2, Items 2.2 and 2.3).
- Chemically resistant to fresh water, seawater, diluted acids and diluted caustic solutions; temporarily resistant to fuels and oils.
- Easy processing with manual, pneumatic or electric piston guns in a wide application temperature range.
Technical specifications
- Chemical base: Silane Terminated Polymer
- Colour: White, Black, Grey, Brown
- Cure mechanism: Moisture‑curing
- Density (uncured): 1.5 kg/l (approx. 1.51 g/cm³ at 20 °C)
- Non‑sag properties: Very good
- Application temperature: +5 °C to +40 °C
- Optimum substrate and product temperature: +15 °C to +25 °C
- Skin time: approx. 35 minutes (23 °C / 50 % r.h.)
- Open time: approx. 20 minutes (23 °C / 50 % r.h.)
- Curing speed: Moisture‑dependent (see manufacturer diagram; slower at lower temperature/humidity)
- Shrinkage: 1 %
- Shore A hardness: 45 (CQP023‑1 / ISO 48‑4)
- Tensile strength: 2.2 MPa (CQP036‑1 / ISO 527)
- Elongation at break: 500 % (CQP036‑1 / ISO 527)
- Tear propagation resistance: 15 N/mm (CQP045‑1 / ISO 34)
- Service temperature: −50 °C to +80 °C
- Flash point (uncured product): approx. 101 °C (closed cup)
- Water solubility: Insoluble
- Vapour pressure: 0.01 hPa
- Shelf life: 12 months (storage below 25 °C, unopened)
- Physical state: Liquid, paste‑like appearance, slight odour, various colours
- Packaging: Mini Unipack 70 ml; Cartridge 300 ml; Unipack 400 ml and 600 ml
Cure mechanism
- Moisture in the air reacts with the polymer to form an elastic sealant.
- Lower temperatures and humidity slow down the curing reaction.
Chemical resistance
- 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, concentrated caustic solutions or solvents.
Applications and use cases
- Marine sealing and bonding: Interior and exterior joints on boats and marine structures.
- Elastic joints resistant to vibration: Ideal where movement and vibration are present in marine environments.
- Above and below waterline: Suitable for sealing applications below the waterline on boats.
- Substrates: Metals (particularly aluminium), metal primers, paint coatings, sheet steel, ceramic materials and certain plastics commonly used in the marine industry.
Tests on actual substrates and under real conditions must always be performed to confirm adhesion and material compatibility.
Application guidelines
- Surface preparation: Substrates must be clean, dry and free from grease, oil and dust. Surface treatment depends on the specific substrate and is critical for long-term adhesion.
- Pre-treatment: Suggestions are provided in the relevant Sika Pre-treatment Chart for marine sealing and bonding and must be confirmed by tests on original substrates.
- Application: Apply between +5 °C and +40 °C, taking into account changes in reactivity and handling. The optimum temperature is +15 °C to +25 °C.
- Tools: Process with hand, pneumatic or electric driven piston guns.
- Compatibility with polyurethane: If Sikaflex 591 can come into contact with polyurethane products, ensure they are fully cured or wait at least 24 hours before sealing.
- Tooling and finishing: Must be carried out within the skin time. Use Sika Tooling Agent N or test any other finishing agent for suitability beforehand.
- Removal: Uncured product can be removed from tools and equipment using Sika Remover‑208 or other suitable solvent. Cured material can only be removed mechanically.
- Skin cleaning: Immediately clean hands and exposed skin with wipes such as Sika Cleaner‑350H or a suitable industrial hand cleaner and water. Do not use solvents on skin.
Application limits
- Light colours of Sikaflex 591 may discolour when in contact with teak wood.
- Perform preliminary tests and seek advice before using on materials prone to stress cracking (such as certain plastics).
FAQ
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Is SIKAFLEX 591 suitable for use below the waterline?
Yes. The product is specified as suitable for sealing applications below the waterline on boats, provided that adhesion to the specific substrate has been confirmed by tests.
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On which substrates can I use SIKAFLEX 591?
It bonds to many materials commonly used in the maritime industry, including metals (especially aluminium), metal primers, paint coatings, sheet steel, ceramic materials and certain plastics. Always perform adhesion tests on the actual substrates.
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What is the recommended application temperature range?
It can be applied between +5 °C and +40 °C. For best handling and curing, keep both substrate and product between +15 °C and +25 °C.
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How long does SIKAFLEX 591 take to skin and cure?
At 23 °C and 50 % relative humidity, skin time is about 35 minutes and open time about 20 minutes. The full curing speed depends on temperature and humidity and is slower in cold, dry conditions.
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Can I smooth the joints after application?
Yes. Tooling and finishing must be carried out within the skin time, preferably using Sika Tooling Agent N or another previously tested finishing agent.
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How do I remove fresh or cured material?
Uncured Sikaflex 591 can be removed from tools and equipment with Sika Remover‑208 or another suitable solvent. Once cured, it can only be removed mechanically.
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What is the shelf life and how should I store the product?
The shelf life is 12 months when stored unopened below 25 °C in a dry, well‑ventilated place, in accordance with local regulations.
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Is the product classified as hazardous for transport?
No. According to ADR, IMDG and IATA, Sikaflex 591 is not regulated as a dangerous good.
Transport information (Section 14)
- ADR: Not classified/regulated as a dangerous good.
- IMDG: Not classified/regulated as a dangerous good.
- IATA (Cargo and Passenger): Not classified/regulated as a dangerous good.
- UN number or ID number: Not applicable (not regulated as dangerous goods).
- UN proper shipping name: Not applicable.
- Transport hazard class(es): Not applicable.
- Packing group: Not applicable.
- Environmental hazards: Not classified as hazardous to the environment for transport purposes.
- Special precautions for user: Not applicable.
- Maritime transport in bulk according to IMO instruments: Not applicable for product as supplied.
Personal protective equipment (Section 8)
When handling SIKAFLEX 591, maintain air concentrations below occupational exposure limits and ensure adequate ventilation, especially in confined spaces. The following personal protective equipment is indicated in the safety data sheet:
- Eye and face protection: Safety glasses.
- Hand protection: Chemical‑resistant, impervious gloves complying with EN 374. Recommended material: butyl rubber/nitrile rubber gloves with thickness > 0.1 mm. Follow glove manufacturer’s instructions regarding breakthrough times and replacement.
- Skin and body protection: Protective clothing such as safety shoes according to EN ISO 20345, long‑sleeved work clothing and long trousers. Rubber aprons and protective boots are additionally recommended for mixing and stirring operations.
- Respiratory protection: If ventilation is inadequate, wear suitable respiratory protection. Select an organic vapour filter (Type A) matched to the expected concentration (e.g. A1, A2 or A3) and ensure that exposure remains within the safe working limits of the selected respirator.
- Engineering controls: Provide local exhaust extraction or general ventilation (according to EN 689 methods) particularly in mixing or stirring zones. If these measures do not keep exposure below occupational limits, respiratory protection is required.
- Environmental exposure controls: No special environmental precautions are required during normal handling, but avoid unnecessary release to the environment.
*Contenido generado por IA
