Sikaflex®-258 EP
Assembly adhesive with reduced pre-treatment requirements
Sikaflex®-258 EP is a 1-component multipurpose assembly adhesive. It is easy to apply and has a paste-like consistency. Sikaflex®-258 EP provides a long open time and ensures a safe application even under warm conditions. It bonds well to a wide range of substrates with minimal pre-treatment.
- Wide adhesion range
- Good application behavior and workability
- Good bead stability and non-sag property
- Short cut-off string
PRODUCT BENEFITS
- Wide adhesion range
- Good application behavior and workability
- Good bead stability and non-sag property
- Short cut-off string
Areas of Application
Sikaflex®-258 EP is suitable for various applications such as assembly bonding within the vehicle manufacturing business. Suitable substrate materials are timber, metals, particularly aluminum (including anodized components), sheet steel (including phosphated, chromated and galvanized components), metal primers and paint coatings (2-component systems), ceramic materials and plastics. Seek manufacturer’s advice and perform tests on original substrates before using Sikaflex®-258 EP on materials prone to stress cracking. Sikaflex®-258 EP is suitable for experienced professional users only. Test with actual substrates and conditions have to be performed ensuring adhesion and material compatibility.Product Details
| Chemical base | Polyurethane | |
| Color (CQP001-1) | Black | |
| Cure mechanism | Moisture curing | |
| Density (uncured) | 1.3 kg/l | |
| Non-sag properties (CQP061-1) | Good | |
| Application temperature | 5 ─ 40 °C | |
| Skin time (CQP019-1) | 55 minutes A | |
| Open time (CQP526-1) | 45 minutes A | |
| Curing speed (CQP049-1) | (see diagram 1) | |
| Shore A hardness (CQP023-1 / ISO 48-4) | 50 | |
| Tensile strength (CQP036-1 / ISO 527) | 4.5 MPa | |
| Elongation at break (CQP036-1 / ISO 527) | 450 % | |
| Tear propagation resistance (CQP045-1 / ISO 34) | 14 N/mm | |
| Tensile lap-shear strength (CQP046-1 / ISO 4587) | 2.5 MPa | |
| Service temperature (CQP509-1 / CQP513-1) | -50 ─ 90 °C | |
| Shelf life | 12 months B |
| CQP = Corporate Quality Procedure | A) 23 °C / 50 % r. h. | B) stored below 25 °C |
CURE MECHANISM
Sikaflex®-258 EP 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®-258 EP
CHEMICAL RESISTANCE
Sikaflex®-258 EP 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.
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
Sikaflex®-258 EP can be processed between 5 °C and 40 °C (climate and product) but changes in reactivity and application properties have to be considered. The optimum temperature for substrate and sealant is between 15 °C and 25 °C.
Consider the viscosity increase at low temperature. For easy application, condition the adhesive at ambient temperature prior to use. To ensure a uniform thickness of the bondline it is recommend to apply the adhesive in form of a triangular bead (see figure 1).
Figure 1: Recommended bead configuration
Sikaflex®-258 EP can be processed with hand, pneumatic or electric driven piston guns. The open time is significantly shorter in hot and humid climate. The parts must always be installed within the open time. Never join bonding parts if the adhesive has built a skin.
Removal
Uncured Sikaflex®-258 EP 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 hand wipes such as Sika® Cleaner-350H or a suitable industrial hand cleaner and water.
Do not use solvents on skin.