Bonding agent thickness

Chemosil (Henkel) Vulcanisation method Vulcanising temperature Prebake resistance Recommended thickness of the dried film 

Primer 211 or X2138 Minimum 5 Xm Recommended 8-10 Xm Stress corrosion resistance 10 - 15 xm 

XV5524 XV4250 C, T,I Optimum 130-180 °C Greater than Chemosil 222 and less than Chemosil 411 Recommended 10-20 pm up to 30 pm possible 

231G C, T,I 130-180 °C Normal Minimum 10 pm Recommended 15-20 pm Apply two coats if necessary 

C = Compression moulding I = Injection moulding T = Transfer moulding  

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For several years the bonding agents have consisted of proprietary polymer/solvent solutions, with a primer coat based on phenolic-style resins and a topcoat formed from solutions of polymers and other ingredients. The formulation of these materials is not disclosed, but much patent literature is available. Bond formation appears to be associated with the development of a very high modulus layer in the rubber immediately adjacent to the surface of the substrate. The thickness of the layer is of the order of 15 pm and... 

Thickeners, fillers, and thixotropic agents are also commonly used to control flow and the bond line s thickness within a joint. Scrims, carriers, and woven reinforcements are other methods commonly used to control bond line thickness. 

The viscosity of epoxy resins and curing agents can be used to control the bond line thickness within the adhesive joint. But the bond line can also be regulated by the incorporation of fillers, by the use of scrim cloth or woven tapes as internal shims within the adhesive itself, or by the careful regulation of the cure cycle. 

Bonding agents may be applied in a number of ways. To make an effective bond an even coat of the bonding system is required of the correct thickness. The method of application is not important provided that an even coat of correct thickness is applied. Methods of application are ... 

Applied film thickness is critical for use of these systems. If the film is too thin, then spotty bonding will result. Too much bonding agent applied will result in delamination and will cause flaking. Best film thicknesses have been determined by Bond [4] to be ... 

Correct viscosity of the applied bonding agent must be controlled by methods other than those used with solvent-based systems. Cup or rotary viscosity testers are not reliable methods of determining viscosity of emulsions. Hydrometer testing of specific gravity is a more reliable way of measuring viscosity and hence controlling deposited film thickness. 

Figure 4.1 Effect of application thickness of bonding agent Chemosil 211 Chemosil 211 (primer solvent-based) 411 Chemosil 411 (topcoat solvent-based) XW7500 Chemosil XW7500 (topcoat waterborne) APIO Thixon APIO (primer waterborne) 5005 Thixon 5005 (topcoat waterborne) XW1190 Chemosil XW1190...

A relatively inexpensive bonding agent that may be used to ensure a positive bond of a new concrete overlay is a latex-reinforced cement slurry grout. Portland cement and sand (in a ratio of 1 3 by volume) are combined with a gauging liquid that is a mixture of equal volumes of water and an acrylic or polyvinyl acetate latex emulsion, as described in the table. This emulsion must be nonre-emulsifiable. The gauging hquid, based on the latex blend, is added to the cement-sand powder until a creamy paste is developed. This paste is scrubbed into the surface of the base slab, covering the surface thoroughly. New concrete is then placed on this bond hue, which is approximately M6-in thick. 

The latex bonding agent should not be used by itself because too much could be absorbed by a porous substrate, leaving a minimal thickness in the glue line. It may also dry too quickly to form an effective bond by the time new concrete is applied. It is best used in the form of a slurry grout. 

One of the recent contributions to rubber technology has been the development of methods whereby both natural and synthetic, both cured and uncured, may be bonded directly to metal surfaces. Earliest methods used to fasten rubber to metal were mechanical. Ebonite was also used in early work, the ebonite surface giving a strong adhesion to the metal while uniting with the rubber on the other side. Ebonite as a bonding agent reduces the flexibility of the unit as a whole, especially when the rubber section itself is not very thick. Secondly, ebonite is thermoplastic and the tenacity of the bond falls off rapidly even at moderate temperature. Recently, other modified derivatives of rubber have become avail-... 

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