Sikaflex®-508
Low emission multipurpose STP sealant
Sikaflex®-508 is a low emission one-component isocyanate free sealant based on the Sika Silane Terminated Polymer (STP) technology which cures on exposure to atmospheric humidity. Sikaflex®-508 meets the most severe environment, health and safety standards and sets a new benchmark in this technology.
- Very low emission
- Compatible with foamed polysterene (XPS)
- Bonds well to a wide variety of substrates without the need for special pre-treatments
- Easy to process
- Low odour
- Isocyanate, phtalate, plasticizer, solvent and PVC free
PRODUCT BENEFITS
- Very low emission
- Compatible with foamed polysterene (XPS)
- Bonds well to a wide variety of substrates without the need for special pre-treatments
- Easy to process
- Low odour
- Isocyanate, phtalate, plasticizer, solvent and PVC free
Usage
Sikaflex®-508 is a low modulus multipurpose sealant for internal and external applications. It adheres well to a wide variety of substrates and is especially compatible with foamed polystyrene foams (XPS). Seek manufacturer’s advice and perform tests on original substrates before using Sikaflex®-508 on materials prone to stress cracking. This product is suitable for experienced professional users only. Tests with actual substrates and conditions have to be performed ensuring adhesion and material compatibility.Packaging
| Cartridge | 300 ml |
| Unipack | 600 ml |
| Drum | 195 l |
Product Details
| Chemical base | Silane Terminated Polymer | |
| Colour (CQP001-1) | Black A | Black A |
| Cure mechanism | Moisture-curing | |
| Density (uncured) | 1.4 kg/l | |
| Non-sag properties | Good | |
| Application temperature | ambient | 5 – 40 °C |
| Skin time (CQP019-1) | 55 minutes B | |
| Curing speed (CQP049-1) | (see diagram) | |
| Shrinkage (CQP014-1) | 1 % | |
| Shore A hardness (CQP023-1 / ISO 48-4) | 30 | |
| Tensile strength (CQP036-1 / ISO 527) | 1.5 MPa | |
| Elongation at break (CQP036-1 / ISO 527) | 250 % | |
| Tear propagation resistance (CQP045-1 / ISO 34) | 4 N/mm | |
| Service temperature (CQP513-1) | - 50 – 80 °C | |
| Shelf life | Drum Unipack Cartridge | 9 months C 15 months C 15 months C |
| CQP = Corporate Quality Procedure | A) Other colors available on request | B) 23°C / 50% r.h. | C) Storage below 25°C |
CURE MECHANISM
Sikaflex®-508 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 1: Curing speed Sikaflex®-508
CHEMICAL RESISTANCE
Sikaflex®-508 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.
The above information is offered for general guidance only. Advice on specific applications will be given on request.
Application
Surface Preparation
Surfaces must be clean, dry and free from grease, oil, dust and contaminants.
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. Consider that these suggestions are based on experience and have in any case to be verified by tests on original substrates.
Application
Place the unipack in the application gun and snip off the closure clip. Cut off the tip of the nozzle to suit desired joint and apply the sealant with a suitable caulking gun. Take care to avoid air entrapment in the joint.
Sikaflex®-508 is processed between 5 °C and 40 °C (change in reactivity needs to be considered). The optimum temperature for substrate and sealant is between 15 °C and 25 °C.
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 sealant. It is recommended using Sika® Tooling Agent N. Other finishing agents must be tested for suitability and compatibility prior the use.
Removal
Uncured Sikaflex®-508 can be removed from tools and equipment with Sika® Remover-208 or another suitable solvent. Once cured, the material can only be removed mechanically.
Hands and exposed skin have to be washed immediately using Sika® Cleaner-350H or a suitable industrial hand cleaner and water. Do not use solvents on skin!
Overpainting
Sikaflex®-508 can be overpainted within the skin formation time. 2 component epoxy paints are usually suitable. Other paints must be tested for compatibility by carrying out preliminary trials under manufacturing conditions. The elasticity of paints is usually lower than of elastomers what could lead to cracking of the paint film in the joint area.