Master Bond manufactures a wide range of adhesives for bonding rubbers to rubbers, as well as rubbers to other substrates. Surface preparation plays a key role in ensuring that good bond strength is achieved. The following techniques are typically used as practices for proper surface preparation:

Degreasing

Degreasing is carried out in order to remove any loosely held dirt or other contaminants from the surface. Surfaces can be degreased using volatile solvents such as toluene, acetone, methyl ethyl ketone, methyl alcohol, isopropyl alcohol and trichloroethylene. However, kindly make sure that all the environmental, health and safety regulations are met prior to selecting a solvent. The most common methods used, typically include the three main steps:

  1. Vapor degrease/clean/rinse the parts with the appropriate solvents
  2. Immerse the substrates in a fresh bath of solvent for the wash and follow by an immersion in the second tank for a rinse
  3. Cleaning and drying the substrate post the degreasing

Abrasion

The surfaces need to be degreased and cleaned before as well as after abrasion to remove any pre-existing contaminants on the surface. Once the surfaces have been abraded, they need to be degreased to remove the debris from abrasion.

Depending on the exact rubber being used, the abrasion technique that is eventually employed might vary. Please note caution must be exercised based on the exact material used regarding the feasibility of this technique.

Chemical Treatment

Specific chemical techniques have been developed for treating different substrates. These treatments change the physical as well as the chemical properties of the surface in order to improve the adhesion. A wide range of acids and alkalis are used for this purpose. Typically the specific chemical or a mixture of chemicals is placed in a chemically resistant container. The chemical bath is then heated to the appropriate temperature and the rubber is immersed in the chemical bath for the required amount of time. After chemically treating the surfaces, it is important to rinse the surface with DI water and thoroughly dry the surface before it is subjected to further use. Extreme care should be taken while handling chemicals. Good laboratory skills should be used while handling these chemicals. The personnel should be wearing the appropriate personal protective equipment and should be well trained in handling of these chemicals.


The three most common techniques used for surface treating rubber substrates are:

  1. Trichloroethylene Solvent: Degrease the rubber substrate as mentioned above using trichloroethylene solvent.
  2. Modified Bleach Solution: Prepare the modified bleach solution by pouring cold DI water (1 liter) into a clean container made of plastics, glass or similar inert ware. While stirring the water, add concentrated hydrochloric acid (5 ml) in a slow steady stream. Then add household bleach (30 ml), stirring it thoroughly into the diluted acid. Immerse the rubber substrate in modified bleach solution for 1-3 minutes at room temperature. Following that, rinse it in cold DI water, followed by a rinse in hot DI water. Finally dry the substrate in hot air.
  3. Sulfuric Acid Solution: Immerse the rubber substrate in concentrated sulfuric acid for 2-10 minutes. Following that, rinse it in cold DI water, followed by a rinse in hot DI water. Finally dry the substrate in hot air.
  4.  

    The table below lists the chemical treatments typically used for some most commonly used rubber substrates:

     

    Substrate Trichloroethylene Solvent Modified Bleach Solution Sulfuric Acid Solution
    Butyl E E --
    Ethylene propylene
    diene monomer
    (EPDMR)
    E G G
    Natural G E --
    Neoprene -- -- E
    Nitrile E E --
    Styrene-butadiene -- -- G

      (E) Excellent   (G) Good   (--) Not Recommended
     

    A combination of degreasing, abrasion, and chemical treatment techniques can be employed for preparing rubber surfaces.

     

    Disclaimer: Please ensure that the appropriate precautions are exercised to ensure suitability in terms of safety, health and feasibility of the techniques included here. Please note that this guide should not be used for any specification purposes.

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