SikaFlex 521 UV black 300ml

Adhesive putty based on STP, weather resistant with a wide range of adhesion

TYPICAL PRODUCT INFORMATION
Chemical base: STP (Silane Terminated Polymer)
Color (CQP001-1): White, Grey, Black
Curing mechanism: Atmospheric humidity
Density (uncured material) depending on the color: 1.4 kg/l
Stability: Good
Ambient application temperature: 5-40 °C
Surface skin formation time (CQP019-1): 30 minutes
Volume change (CQP014-1): 2%
Shore A hardness (CQP023-1/ISO 48-4): 40
Tensile strength (CQP036-1/ISO 527): 1.8 MPa
Elongation at break (CQP036-1/ISO 37): 400%
Tensile strength (CQP045-1/ISO 34): 5.5 N/mm
Temperature resistance (CQP509-1/CQP513-1): -50 to 90 °C
4 hours: 140 °C
1 hour: 150 °C
Shelf life of cartridge / single portion: 12 months
barrel / cask: 9 months

CQP = Corporate Quality Procedure A) 23 °C / 50% r. h. B) storage below 25 °C

DESCRIPTION
Sikaflex®-521 UV is a 1-component STP adhesive/sealant resistant to weathering,
which exhibits good adhesion to a wide range
surfaces such as metals, ABS, PC, FRP and wood,
usually without the need for special surface preparation.
This multi-purpose product is suitable for
internal and external applications.

ADVANTAGES
▪Resistant to aging and weathering
▪Good adhesion to various substrates without the need for special pretreatment
▪Without isocyanates and without solvents
▪Paintable
▪Sandable
▪Low odor

AREAS OF USE
Sikaflex®-521 UV exhibits good adhesion to a wide range of substrates and is suitable for forming
permanent elastic joints. Suitable substrates are wood, metals, primers for metals and
coatings (2K systems), ceramic materials and
plastics. This multi-purpose product is convenient
for indoor and outdoor applications.
For applications with materials prone to formation
stress cracks, perform tests on original substrates, request expert advice from Sika Industry.
This product is intended for professional use, before application it is necessary to carry out adhesion tests with current substrates and conditions.

CURE MECHANISM
Sikaflex®-521 UV cures by reacting with air
humidity. At lower temperatures, the water content is
(humidity) in the air generally lower and reactions
curing takes place more slowly

CHEMICAL RESISTANCE
Sikaflex®-521 UV is generally resistant to fresh water, sea water, dilute acids
and diluted lyes; short-term resistant to
fuels, mineral oils, vegetable and animal fats and oils.
Sikaflex®-521 UV is not resistant to organics
acids, glycolic alcohol, concentrated mineral acids and caustic solutions or solvents.

METHOD OF APPLICATION
Preparation of documents
Surfaces must be clean, dry and free of grease, oil and dust.
The finish depends on the specific nature
foundations and is essential for a long-term bond
/ connection. Refer to the current edition of the relevant document for surface preparation suggestions
Sika® Pre-Treatment Chart. take into account
that these suggestions are based on experience and must
be verified in each case by tests on
original documents.

Smoothing and embedding the surface
Smoothing and finishing must be done before creating the surface skin of the product.
We recommend using Sika® for smoothing
Tooling Agent N. Other preparations must be
tested before use for suitability, compatibility.

Removal
Uncured Sikaflex®-521 UV can be removed from
tools and equipment using Sika® Remover-208
or other suitable solvent. After hardening, the material can only be removed mechanically.
Hands and exposed skin should be treated immediately with Sika® Handclean wipes or
another suitable industrial hand cleaner,
by water.
Do not use solvents on the skin!
Uncured Sikaflex®-521 UV can be removed from
tools and equipment using Sika® Remover-208
or other suitable solvent. After hardening, the material can only be removed mechanically.
Hands and exposed skin should be treated immediately with Sika® Handclean wipes or
another suitable industrial hand cleaner,
by water.
Do not use solvents on the skin!

Application
Sikaflex®-521 UV can be processed between 5 °C
and 40°C, but changes in reactivity and application properties must be taken into account. Optimal temperature
of the substrate and sealant is between 15 °C and 25 °C.
Sikaflex®-521 UV can be processed with manual, pneumatic or electrically driven piston guns, or also with pumping equipment (pump). For advice on
for selecting and setting up a suitable pumping system, contact Sika Industry's system engineering department.

According to Directive (EC) No. 1272/2008, it is not a dangerous substance or mixture.
EUH208 Contains trimethoxyvinylsilane. May cause an allergic reaction.
EUH211 Attention! Hazardous respirable droplets may form when sprayed. Do not inhale aerosols or mist.