Sikaflex®-221 RLT

Adhesive sealant for air-conditioning, ventilation and cleanroom systems

Sikaflex®-221 RLT is a 1-component polyurethane adhesive sealant that bonds well to a variety of substrates. It is especially designed to meet the requirements of air-conditioning, ventilation and cleanroom systems.  

  • Meets hygiene requirements for ventilation and air-conditioning systems and units according VDI 6022 Blatt 1:2018-01
  • Resistant to microorgansims growth according DIN EN ISO 846: 2019-08
  • Bonds well to a wide variety of substrates
  • Can be sanded and painted
  • Good ageing resistance
  • Silicone-free
  • Non-corrosive
  • Low odor
 
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PRODUCT BENEFITS

  • Meets hygiene requirements for ventilation and air-conditioning systems and units according VDI 6022 Blatt 1:2018-01
  • Resistant to microorgansims growth according DIN EN ISO 846: 2019-08
  • Bonds well to a wide variety of substrates
  • Can be sanded and painted
  • Good ageing resistance
  • Silicone-free
  • Non-corrosive
  • Low odor
 

Areas of Application

Sikaflex®-221 RLT is designed for sealing and bonding of ventilation and air conditioning sysems. Possible substrate materials are are timber; metals, 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®-221 RLT 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.  

Product Details

Typical Product Data
Chemical base

1-component polyurethane

Color (CQP001-1)

White, grey

Cure mechanism

Moisture-curing

Density (uncured)

depending on color

1.27 kg/l

Non-sag properties

Good

Application temperature

5 ─ 35 °C

Skin time (CQP019-1)

60 minutes A

Curing speed (CQP049-1)

See diagram

Shrinkage (CQP014-1)

5 %

Shore A hardness (CQP023-1 / ISO 48-4)

40

Tensile strength (CQP036-1 / ISO 527)

1.4 MPa A

Elongation at break (CQP036-1 / ISO 527)

450 % A

Tear propagation resistance (CQP045-1 / ISO 34)

6 N/mm A

Service temperature (CQP513-1)


1 day
1 hour

-40 ─ 90 °C
120 °C
140 °C

Shelf life (CQP016-1)

12 months B

CQP = Corporate Quality Procedure

A) 23 °C / 50 % r. h.

B) stored below 25°C
Technical Information

CURE MECHANISM

Sikaflex®-221 RLT 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).

en_PNG_01-diagram-sikaflex-221rlt

Diagram 1: Curing speed Sikaflex®-221 RLT

CHEMICAL RESISTANCE

Sikaflex®-221 RLT 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

Application Information

Surface preparation

Surfaces must be clean, dry and free from grease, oil and dust.
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®-221 RLT can be processed between 5 °C and 35 °C 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.

Sikaflex®-221 RLT can be processed with manual, pneumatic or electric driven piston guns as well as pump equipment.

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 product. It is recommended using Sika® Tooling Agent N. Other finishing agents must be tested for suitability and compatibility prior the use.

Removal

Uncured Sikaflex®-221 RLT 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.

Overpainting

Sikaflex®-221 RLT can be painted after formation of a skin. If the paint requires a baking process, best performance is achieved by allowing the sealant to fully cure first. 1C-PUR and 2C-acrylic based paints are usually suitable.

All paints have to be tested by carrying preliminary trials under manufacturing conditions.

The elasticity of paints is usually lower than of sealants what could lead to cracking of the paint film in the joint area.