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Polyurethane Joint Sealant - Koster PU Flex 25

Verified by manufacturer 5 months ago

Koster Aquatecnic Ltd Third party certifications:
  • ISO 9001 Quality Management

    Certificate type

A highly elastic polyurethane joint sealant. Single component, easy to use and UV stable.

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+44 (0)1387 270252 Website

Application

Designed for civil and industrial movement, expansion, control and dilatation joints in both architectural and heavy construction.

Contact the manufacturer's technical team for more information or for specification support.

Description

Koster PU-Flex 25 is a highly elastic, low modulus polyurethane sealant, with good UV resistance and excellent adhesion to typical construction materials. Koster PU-Flex 25 is one component and cures with moisture to form a flexible sealant which can be overpainted after curing is finished.


Features and benefits:

  • The sealant is non sagging.
  • Highly thixotropic.
  • Easy smoothing and workability.
  • Highly elastic joint sealant.
  • Multiple substrate application - Easy application on horizontal. and vertical surfaces.
  • For interior and exterior use.
  • Single component - no mixing required.
  • Fast application with only a caulking gun.
  • Less waste through tubular bags instead of plastic cartridges.


Designed for civil and industrial movement, expansion, control and dilatation joints in both architectural and heavy construction. This versatile material can be used to seal many types of substrates including:

Porous substrates (no primer required):

  • Concrete.
  • Mortar.
  • Brickwork.
  • Blockwork.
  • Natural and synthetic stone, etc.

Non-porous substrates (Koster PU Primer 120 required):

  • Metal.
  • Steel.
  • Aluminum.
  • Wood.
  • Ceramic tiles.
  • Rigid plastics, etc.


Preparation and priming:

Ensure that the air and substrate temperatures are +5°C or higher and that all surfaces are clean, dry and free from dust and grease. Clean, porous, absorbent substrates require no primer. Use Koster PU Primer 120 for nonporous (non-absorbing) surfaces.


Insert a closed-cell foam backing rod into the joint. this backing rod should be compressible and tight fitting. Depth for insertion will depend on the joint width (see below for ratio advice).


Application:

Koster PU-Flex 25 is installed with the Koster Special Caulking Gun (without attachments). Joint widths up to 10 mm are filled in the width / height ratio 1:1, from 10 to 30 mm with a ratio of 2:1. For critical substrates or unknown materials it is recommended to carry out adhesive pull-off tests prior to installation. If the substrate has a layer which may not be removed (eg coatings), adhesion and compatibility tests must be carried out in advance.


Hand pump the material into the joint - against the backing rod - until it is flush with the wall surface. Finally smooth the uncured material.


Materials:

  • Primer: Koster PU Primer 120.
  • Sealant: Koster PU Flex 25.
  • Backing rod: Closed cell (by others).


For further information or design assistance, please contact Technical@kosteruk.com and we will be happy to assist.

General information

Color

Grey

Finish

Matt

Material

Polyurethane (PUR)

Shape

Formless

Length

Bespoke

Width

Bespoke

Height

Bespoke

Warranty description

Ten year

Uniclass

Pr_30_31_76_65 Polyurethane (PUR) construction joint sealantsPrimary

CAWS

M21/85 Sealant joints

Q21/650 Cold joint sealing

P31/710 Sealing

P31/40 Sealing around services

M12/65 Sealant movement joints

M40/75 Sealant movement joints

M21/530 Sealant joints

Q21/650 Cold joint sealing

M40/815 Sealant movement joints

H13/740 Sealant joints

L20/820 Sealant joints

L10/75 Sealant joints

L20/80 Sealant joints

M12/430 Sealant movement joints

L10/810 Sealant joints

E40/530 Sealant

Product range

Flooring Systems
Roofing Systems
Expansion Joint Systems

Specification data - Polyurethane (PUR) construction joint sealants

Standard

To BS EN ISO 11600.

Material

One-part polyurethane.

Class

F-25LM.

Colour

Grey RAL 7040.

Bonding primer

Koster PU Primer.

Guidance for specification option:

For non-porous surfaces.

No primer.

Guidance for specification option:

For clean, porous and dry surfaces.

Cleaning

Clean tools using Koster PUR Cleaner after use.

Package

600 mL foil cartridge.

Curing Time:

2 mm after 24 hours (at 25°C and 50%).

Skin formation at 23°C and 50% Relative Humidity (RH)

Three hours.

Joint width

Maximum of 30 mm.

Elongation at break

>600%.

Viscosity

Non sag.

Temperature resistance

-30°C to + 80°C.

Joint movement

±35%.

Shrinkage

5%.

Elastic recovery

Recovery from deformation 90%.

E modulus

0.22 MPa.

Shore hardness - A

Approximately 25.

Density / Specific gravity

Approximately 1.32 g/cm³.

Sustainability data

Contains Red List materials

No

Country of material origin

Germany

Country of product manufacture

Germany

Recyclability

Packaging is easily and fully recyclable.

Manufacturer guidance

Packaging is easily and fully recyclable.

Recycled content

As defined in clause 7.8 of BS EN ISO 14021

0 %

Third party certifications

ISO 9001 Quality Management

ISO 9001 Quality Management

Koster Bauchemie AG - ISO 9001 Certificate

Literature

Koster Waterproofing of Construction Joints

Koster Waterproofing of Construction Joints