Cilbond® 49SF

Bonding Capabilities:

• Cilbond 49SF is a one coat bonding system for PU’s and TPU’S to all metals during the curing process.
• Cilbond 49SF will also bond PU’s and TPU’s to epoxies and fibreglass reinforced plastics, polyamides and other engineering thermoplastics, such as Hytrel® , PBT, PET, PPS, PPO, PEEK, PES, etc.

In-service Benefits:

• Cilbond 49SF exhibits good resistance to static and dynamic fatigue and bonds survive in fluids such as fuels, oils including all types of lubricants, glycols, inks, lacquers, paints and many cleaning solvents, though for a maximum resistance to aggressive solvents, the use of Cilbond 49SF and Cilcure B is recommended – see below. (Cilcure B is a liquid form of diphenylmethane diisocyanate with a selected functionality and is used to improve the environmental resistance of bonded parts).
• Cilbond 49SF has good hot and cold water resistance, as illustrated by tests where polyether/MbOCA or polyester/Ethacure cured compounds bonded to mild steel showed 100% rubber tear when peel tested after total immersion for 28 days in water at 80°C. Bonds made with Cilbond 49SF are impact resistant and not brittle down to at least -40°C.
• When Cilbond 49SF is used as a 2 part bonding agent with Cilcure B, it has specific benefits and uses, especially for lower temperature bonding and for exceptional resistance to aqueous conditions, such as boiling water and for long-term exposure to predominantly wet conditions. This system is also suited for higher heat resistance to 180C and Cilbond 49SF + Cilcure B is probably more versatile when used as a primer under Cilbond 49SF.

​​​​​Processing Benefits:

• Cilbond 49SF exhibits the capability to withstand long pre-bake cycles and with good control of metal preparation and bonding agent application and using extended pre-bake conditions (see below) the bonds can survive up to ca. 130°C in static and dynamic conditions.

Where to Use:

• Cilbond 49SF will bond castable and thermoplastic polyurethanes to metals and plastics at temperatures of 70°C or above, though best results are achieved at >85°C, particularly if the component is going to be subjected to a severe environment. It is especially suitable for use in dynamic conditions where hydrolytic stability is important.
• When bonding MDI Quasi Prepolymer Systems and where the cast PU bond line may not reach much above 70°C, it is recommended that after applying the Cilbond 49SF, the coated metal parts are dried thoroughly and then pre-baked for an absolute minimum of 1 hr at 85°C - 100°C to ensure a good cement to metal bond.
  For the bonding of PU to polyamides (Nylon), using Cilbond 49SF, refer to CIL Information Sheet B10.

End applications for products using Cilbond 49SF include :

• Rollers for the paper and textile industries
• Solid tyres
• Carriage wheels
• Dunnage
• Pipe linings and pipe coatings
• Reinforced screen decks
• Any product with an engineering bond between a PU elastomer and a metal or plastic substrate.
   

Brushing: Application by brushing is normally undertaken without further dilution, but for coating large areas, dilution with MEK or the diluent blend shown below, improves flow and speed of application.
Dipping: Dilute to a viscosity of 16-24 seconds using a Zahn No.2 cup at 25°C or 13-20 seconds using a Din 4 or Ford 4 Cup at 25°C using the diluent blend given below, or use MEK if a fast drying coating is required.
Spraying: We recommend an HVLP gun using 1.5 Bar air-pressure and a nozzle size of 1 - 1.5mm. Dilute to 16-24 seconds on a Zahn No 2 cup or 13-20 seconds on a DIN 4 or Ford 4 cup at 25°C, using the diluent shown below. If fibrillation (cob webbing) occurs, use diluent containing more higher boiling solvent, such as MPA. Cilbond Diluent 4000 is a suitable diluent for Cilbond 49SF. Typically, dilute ca. 100 parts of CILBOND 49SF with 40-70 parts Cilbond Diluent 4000, by weight or volume, depending on the gun type, the nozzle size and pressures used. If MEK is used as the main diluent, beware of chilling of the sprayed metal parts (due to rapid MEK evaporation) and subsequent condensation of water, which may lead to a micro porous film.

Diluents: The best diluent is the following blend, where parts are by weight:
86 parts Methyl ethyl ketone (MEK)
7 parts Methyl proxitol acetate (MPA)
7 parts Ektapro (EEP), ethoxy ethyl propionate.
This solvent blend is available from CIL as Cilbond Diluent 4000. For many applications it is possible to dilute with low moisture content MEK, provided that the Cilbond 49SF is agitated whilst adding the MEK. If cob webbing occurs on spraying, additions of Cilbond Diluent 4000, or mixtures of MEK and high boiling ethers and/or esters, such as MPA will reduce it.
Roller Coating: Dilute to 35-45 seconds on a DIN 4 or Ford 4 cup at 25°C for most roller application processes. Dilution with a high boiling solvent like MPA may be necessary to achieve the best finish and to reduce the skinning of the bonding agent in the applicator.
Drying: Dry each coat for at least 45 minutes and the final coat for at least 1 hour at room temperature(25°C). At temperatures below 20°C extend the drying time accordingly. Forced drying may be used provided care is taken to prevent blistering of the films so we recommend temperatures below 60C in the early stages of drying. Pre-warming the parts before coating will also aid drying (60°C is recommended).
Pre-Baking:  Pre-baking is required to develop good bonding to the substrate, especially to metals. The minimum pre-bake is 1 hour at 100°C and a typical recommended pre bake is 2 hours at 100-110°C, though it is well established that longer pre-bakes (4-8 hrs at 100°C) do maximise bond strengths, percentage bond retention and especially the heat resistance of the bond and environmental resistance. The Cilbond 49SF coating should not be pre-baked for more than 48 hours at temperatures of ca. 100°C, 24 hours at 110°C or 16 hours at 130°C. Pre-bakes at >130°C should be fully validated and very carefully controlled and especially with porous and hardened metals (particularly cast iron and cast aluminium) as de-gassing may affect the cement to metal bond.
As an alternative to extended pre-bakes, consider using Cilbond 49SF+ Cilcure B as a primer under Cilbond 49SF – See separate section on page 5. Pre-bakes prior to TPU injection moulding are less sensitive to this problem, partly due to the high injection pressures and temperatures involved, which will re-bond the Cilbond 49SF to the metal.
Coating thickness: For general-purpose applications use a dry coating thickness of 15 microns. For dynamic fatigue applications use a dry coating thickness of 20 microns. For severe environments use a dry coating thickness of 25 microns. Under these conditions it is possible to achieve bonds, which exhibit no sign of edge failure after 480 hours salt spray tests, especially with Cilbond 49SF + Cilcure B.
Storage:  Coated parts may be stored for long periods of time (several weeks) provided they are protected from dust and moisture.

Cilbond 49SF is supplied in 10L, 25L and 200L containers. 250ml trial samples are also available upon request.