SIKAFLEX 296

What Sikaflex 296 is and why choose it

Sikaflex 296 is a high-performance, 1-component polyurethane direct glazing adhesive specifically developed for bonding mineral glass windows in the shipbuilding and marine repair industry. It cures on exposure to atmospheric moisture, forming an elastic, durable seal that compensates for movements and fills gaps between glass and substrates. With very good non-sag properties, low odour and the possibility of black primerless application on suitable substrates, it is designed for professional OEM and repair operations where reliable marine glazing is essential.

Main features

• Purpose-designed for marine glazing: Direct bonding of mineral glass windows in shipbuilding and marine repair applications.
• 1-component, moisture-curing PU: Easy processing without mixing; cures with ambient humidity to form an elastic sealant/adhesive.
• Excellent gap-filling and non-sag behaviour: High thixotropy enables application on vertical surfaces without running.
• Durable and weather resistant: Resistant to ageing and weathering for long-term performance in marine environments.
• Low odour, solvent- and PVC‑free: Improves working comfort and reduces solvent emissions.
• Good working time: Approx. 45 minutes skin time and 30 minutes open time at 23 °C / 50 % r.h. (ambient dependent).
• Black primerless application possible: On suitable substrates, according to Sika pre-treatment guidance.
• Smooth finishing: Can be tooled to a very fine finish, ideal for exposed exterior joints around glazing.
• Suitable for manual and pump application: Can be applied with hand, pneumatic or electric piston guns and with pump systems.
• Wheelmark / IMO-compliant: Meets regulations of the International Maritime Organization (IMO) and is Wheelmark approved for marine use.

Technical specifications

• Chemical base: 1-component polyurethane
• Colour: Black
• Cure mechanism: Moisture-curing
• Density (uncured): Approx. 1.2 kg/l (≈ 1.2 g/cm³) at 20–23 °C
• Non-sag properties: Very good
• Application temperature (ambient/product): 10 – 35 °C
• Optimal substrate/adhesive temperature: 15 – 25 °C
• Skin time: Approx. 45 minutes (23 °C / 50 % r.h.)
• Open time: Approx. 30 minutes (23 °C / 50 % r.h.)
• Shrinkage: 1 %
• Shore A hardness: 45 (CQP023-1 / ISO 48-4)
• Tensile strength: 6 MPa (CQP036-1 / ISO 527)
• Elongation at break: 450 % (CQP036-1 / ISO 527)
• Tear propagation resistance: 14 N/mm (CQP045-1 / ISO 34)
• Tensile lap-shear strength: 4.5 MPa (CQP046-1 / ISO 4587)
• Insulation resistance: 10⁸ Ω·cm (CQP079-2 / DIN IEC 60167)
• Service temperature: -40 to +90 °C (CQP509-1 / CQP513-1)
• Flash point: > 101 °C (closed cup)
• Physical state: Paste, black, odourless
• Water solubility: Insoluble; product reacts with water
• Kinematic viscosity: > 20.5 mm²/s at 40 °C
• Vapour pressure: 0.01 hPa
• Shelf life (storage < 25 °C): 9 months in cartridges/unipacks; 6 months in drum/pail
• Chemical resistance (uncured/cured system):
  • 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, strong caustic solutions or solvents.
• Packaging (examples): 300 ml cartridge; 400 ml and 600 ml unipack; 23 l pail; 195 l drum (availability may vary).

Applications and use cases

Intended applications

• Direct glazing of mineral glass windows in shipbuilding (newbuild) projects.
• Direct glazing in marine repair and refit operations.
• Bonding of mineral glass-based marine windows where a durable, elastic adhesive is required.
• Finishing and sealing of exposed joints around marine glazing, where a fine surface finish is desired.

Substrates and compatibility

• Designed for mineral glass-based windows used in marine applications.
• Before installing laminated safety glass with integrated heating elements in the PVB layer, Sika Technical Service must be consulted.
• On materials prone to stress cracking, tests on original substrates must be carried out and manufacturer advice sought before use.

Surface preparation

• Bonding surfaces must be clean, dry and free from grease, oil, dust and other contaminants.
• Surface treatment depends on the specific substrate and is critical for long-lasting adhesion.
• Preparation guidelines are given in the relevant Sika Pre-treatment Chart / Sika priming tables for marine applications.
• These recommendations are based on experience and must be verified by tests on original substrates.

Application guidelines

• Process Sikaflex 296 between 10 and 35 °C (climate and product); consider changes in reactivity and application properties.
• Condition the adhesive to ambient temperature before use to ease extrusion, especially at low temperatures where viscosity increases.
• Apply using suitable equipment:
  • Manual, pneumatic or electric piston guns for cartridges and unipacks.
  • Appropriate pump equipment for bulk packaging (pump system selection to be defined with Sika System Engineering).
• For a uniform bond-line thickness, apply the adhesive as a triangular bead.
• Install the glass within the stated open time. Bonded parts must not be joined once the adhesive has formed a skin.
• Tool and finish the joint within the skin time; Sika Tooling Agent N is recommended. Other finishing agents must be tested for suitability and compatibility.

Curing behaviour

• Cures by reaction with atmospheric moisture.
• At lower temperatures, air humidity is generally lower and cure speed is reduced.
• Curing speed over time is indicated in Sika documentation (see cure diagram for Sikaflex 296).

Cleaning and removal

• Uncured Sikaflex 296 can be removed from tools and equipment with Sika Remover-208 or another suitable solvent.
• Once cured, material can only be removed mechanically.
• Hands and exposed skin must be cleaned immediately using wipes such as Sika Cleaner-350H or a suitable industrial hand cleaner and water.
• Do not use solvents on skin.

FAQ

1. What is Sikaflex 296 used for?

   Sikaflex 296 is used as a direct glazing adhesive for bonding mineral glass windows in the shipbuilding and marine repair industry, and for sealing exposed joints around such glazing.

2. Is it suitable for all types of marine glass?

   It is suitable for mineral glass-based windows used in marine applications. For laminated safety glass with integrated heating elements in the PVB layer, Sika Technical Service must be consulted before installation.

3. Do I need a primer before applying Sikaflex 296?

   Black primerless application is possible on certain substrates; however, surface pre-treatment (cleaner, activator and/or primer) must follow the applicable Sika Pre-treatment Chart, and should be verified by tests on original substrates.

4. How long can I work with the adhesive after application?

   At 23 °C and 50 % relative humidity, the open time is approximately 30 minutes and the skin forms after about 45 minutes. Higher temperatures and humidity shorten these times.

5. Can Sikaflex 296 be applied in cold conditions?

   It can be processed between 10 °C and 35 °C. At lower temperatures the viscosity increases and curing slows down, so the adhesive should be conditioned to ambient temperature before use.

6. How should surfaces be prepared before bonding?

   Surfaces must be clean, dry and free from grease, oil, dust and contaminants. Appropriate Sika cleaners, activators and primers should be used according to Sika’s pre-treatment guidance.

7. How do I remove excess or cured Sikaflex 296?

   Uncured material can be removed with Sika Remover-208 or another suitable solvent. Once cured, it can only be removed mechanically. Skin should be cleaned with suitable hand cleaner and water, not with solvents.

8. Is Sikaflex 296 resistant to seawater and fuels?

   It is generally resistant to fresh water and seawater, and temporarily resistant to fuels, mineral oils and vegetable/animal fats and oils. It is not resistant to organic acids, glycolic alcohol, concentrated mineral acids, strong caustic solutions or solvents.

9. Who should use Sikaflex 296?

   It is intended for experienced professional users only. Tests with actual substrates and conditions must be carried out to ensure adhesion and material compatibility.

10. Is the product classified as dangerous for transport?

    No. Under ADR, IMDG and IATA regulations, Sikaflex 296 is not regulated as a dangerous good.

Section 14 – Transport information

• UN number / ID number: Not regulated as a dangerous good (ADR, IMDG, IATA).
• UN proper shipping name: Not regulated as a dangerous good (ADR, IMDG, IATA).
• Transport hazard class(es): Not regulated as a dangerous good (ADR, IMDG, IATA).
• Packing group: Not regulated as a dangerous good (ADR, IMDG, IATA – Cargo and Passenger).
• Environmental hazards: Not regulated as a dangerous good.
• Special precautions for user: Not applicable.
• Maritime transport in bulk according to IMO instruments: Not applicable for product as supplied.

Section 8 – Personal protective measures

Exposure controls and personal protection

• General ventilation: Maintain air concentrations below occupational exposure limits. Ensure adequate ventilation, especially in confined or mixing areas.
• Eye and face protection:
  • Safety glasses with side shields conforming to EN166.
  • Eye-wash bottle with clean water should be available at the workplace.
• Hand protection:
  • Chemical-resistant, impervious gloves complying with EN 374.
  • Suitable for short-term exposure or splashes: butyl rubber/nitrile rubber gloves (> 0.1 mm).
  • Suitable for permanent exposure: Viton gloves (0.4 mm) with breakthrough time > 30 minutes.
  • Remove contaminated gloves immediately.
• Skin and body protection:
  • Protective clothing such as long-sleeved workwear and long trousers.
  • Safety shoes according to EN ISO 20345.
  • Rubber aprons and protective boots are additionally recommended for mixing and stirring work.
• Respiratory protection:
  • In case of inadequate ventilation, wear respiratory protection.
  • Use a properly fitted, NIOSH-approved air-purifying or air-fed respirator with an organic vapour filter (Type A: A1 < 1000 ppm; A2 < 5000 ppm; A3 < 10000 ppm), according to risk assessment.
• Hygiene measures:
  • Handle in accordance with good industrial hygiene and safety practice.
  • Avoid contact with eyes, skin and clothing.
  • Do not eat, drink or smoke when using this product.
  • Wash hands before breaks and at the end of the workday.
  • Persons with a history of skin sensitisation, asthma, allergies or chronic/recurrent respiratory disease should not work in processes where this mixture is used.
• Environmental exposure control: Do not flush into surface water or sanitary sewer systems; if contamination occurs, inform the relevant authorities.