Silicones, silicone oils, sprays
Casting and potting resins)
HS Code:
3214.1000
Technical Data
Typical values, not a specification. The technical data sheet (TDS) is binding.
Product Information
- Tensile Strength
- approx. 2.5 N/mm²
- Temperature range (°C)
- -40 °C to +90 °C
- Container
- 290ml cartridge, 600ml bag
- Consistency
- Non-slumping, ≤ 3 mm
Performance at Full Cure
- Elongation at break
- approx. 350%
Physical Properties
- Density
- 1.52 g/cm³
- Hardness (Shore A)
- 45
- Chemical group
- Silane-modified polymer
- Color
- black, white, grey
- Cured layer thickness after 24 hours
- ≥ 3.0 mm
- Curing technology
- Moisture curing
Features
- Processing temperature
- +5 °C to +40 °C
- Stress at 100% elongation
- approx. 1.6 N/mm²
- Volume change
- ≤ 5%
- Number of components
- 1K
Product Description
Merbenit HM21 is a universal 1K-SMP sealant adhesive with long open time (30 min), Shore A 45, and 350% elongation at break — certified to EMICODE EC1Plus + Eurofins IAC Gold.
Silyl-modified polymers (SMP) are modern high-performance adhesives — moisture-curing, solvent-free, isocyanate-free, and silicone-free, with a very broad adhesion spectrum on metals, painted and galvanized surfaces, engineering plastics, glass, ceramics, concrete, stone, and wood. Paint-compatible, corrosion-protective, shock- and vibration-resistant, low-odor. HM21 is a specific variant of the Merbenit SMP series — the most important properties and applications are listed below.
Merbenit HM21 is the universal choice of the Merbenit series — 30 minutes of open time allow careful application even on large adhesive seams, with high final strength (Shore A 45) and 350% elongation at break. EMICODE EC1Plus and Eurofins IAC Gold confirm very low-emission processing — suitable for indoor applications.
What sets HM21 apart
What is HM21 used for?
Processing
Recommended accessories
HM21 in comparison with related Merbenit products
Direct comparison of mechanical and processing values — all data from the official Merbenit TDS.
HM21 Current Product |
HT50 → | SF50 → | HS60 → | |
|---|---|---|---|---|
| Crosslinking system | 1K moisture-curing | 1K moisture-curing | 1K moisture-curing | 1K moisture-curing |
| Consistency | Non-sagging, ≤3 mm | non-sag | non-sag | non-sag |
| Shore A hardness | A 45 | A 45 | A 50 | A 60 |
| Tensile Strength | 2.5 N/mm² | 2.5 N/mm² | 3.4 N/mm² | 3.3 N/mm² |
| Elongation at break | 350 % | 200 % | 200 % | 250 % |
| Modulus 100% | 1.6 N/mm² | 1.5 N/mm² | 2.2 N/mm² | 2.3 N/mm² |
| Processing time | 30 min | 10 min | 8 min | 10 min |
| Through-curing 24 h | ≥3.0 mm | 2.5 mm | ≥3.5 mm | ≥2.0 mm |
| Through-cure 48 h | ≥4.0 mm | 4.0 mm | ≥4.5 mm | ≥3.0 mm |
| Density | 1.52 | 1.48 | 1.40 | 1.54 |
| Temperature range | –40 / +90 °C | –40 / +90 °C | –40 / +90 °C | –40 / +90 °C |
| Volume change | ≤5 % | ≤4 % | ≤7 % | ≤8 % |
| Main application | Metal construction | Immediate-bonding applications | Minergie-ECO construction projects | Food industry |
Frequently asked questions about HM21
Practical application and design questions — answered by SILITECH.
Merbenit HM21: Universal 1K-SMP sealant adhesive with long open time (30 min), Shore A 45 and 350% elongation at break — EMICODE EC1Plus + Eurofins IAC Gold certified. Main applications: metal construction, apparatus and mechanical engineering, plastics technology.
SMP = Silane-modified polymer. This modern adhesive class combines the advantages of silicone (elasticity, weather resistance, broad adhesion spectrum) and polyurethane (mechanical strength, paint compatibility) — without their disadvantages (silicone: not paintable, corrosion on some metals; PU: isocyanates, often problematic indoors). SMP adhesives are solvent-free, isocyanate-free, and silicone-free, paint-compatible, corrosion-protective, and adhere without primer to most substrates — except PE, PP, PTFE, and silicones.
HM21 adheres to metals (aluminum, stainless steel, steel), powder-coated and painted surfaces, galvanized/anodized/chromated/zinc-coated substrates, many plastics, ceramics, stone, concrete, render, wood, and glass. Not suitable for: PP, PE, PTFE (Teflon), silicones, and bituminous substrates. For critical material combinations, we recommend a preliminary test or the use of a primer (V40 for smooth, V21 for absorbent substrates).
Store in unopened original container in a dry, cool place — typically between +5 and +30 °C. Consult the safety data sheet (SDS) before use. Observe the expiry date on the packaging. Process opened cartridges promptly — skin formation in the nozzle will block further application.
In the comparison table above, you will find related Merbenit products with different properties — different hardness, pot life, elongation at break, or special certifications (IMO, EN 45545-2, FMVSS 212, ISEGA, Minergie-ECO). If you are unsure about the optimal choice, we will be happy to advise you — contact SILITECH with your specific application (substrate pairing, desired hardness, processing workflow, certification requirement).