Best Practices Surface Modification in Scrap Tires & Rubber Recycling
Processing / Materials Preparation
Page 1 of 2 BP-T2-04-06.doc
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Additives for Surface Modification Material: Recycled Rubber from Tires, Industrial Scrap Rubber, and Post-Consumer Scrap Rubber Products
Virgin rubbers are high viscosity liquids. Recycled rubbers are produced from used rubber items that are higher in viscosity and molecular weight. As a result, it is usually difficult to get good bonding and dispersion of recycled rubber in virgin rubber. Surface modifiers are added to improve the compatibility of recycled rubber with virgin rubber.
A tremendous amount of research has been done in this area. The most practical applications of the surface modifiers are shown below:
Material Supplier Cost, $/lb Use
Urethanes Bayer, Uniroyal 2.00 Moisture Seal
SBR Latex Many 0.50 Binder/Wetting Agent
NR Latex Many 0.60 Binder/Wetting Agent
Ricon 100 (Sol SBR) Ricon Resins 2.30 Binder/Adhesive
Vestenamer Huls 2.00 Thermoplastic Binder
Vestol 28 Struktol 1.00 Curable regrind wetting agent
Struktol 40 MS Struktol \0.60 Noncurable regrind homog. agent
GRA Flow Polymers Unknown Binding Agent
See Fillers-Recycled Crumb Rubber, Recycled Rubber Content Effect on Properties of Virgin Compounds, and
Surface Modified Recyclates Best Practices.
The materials listed above can be added to virgin compounds at application dependent levels during the mixing stage. The ultimate application of the compound will determine the type and amount of additive that needs to be used (e.g., non-similar chemistry blends/additions, base chemistry types, etc.). Any manufacturer making rubber compounds is a candidate to use these materials.
The reason for using surface modifiers is to improve interpolymer compatibility, end-use properties, processing characteristics, and mix consistency when using recycled rubber by improving the surface bonding/adhesion of the virgin rubber and the recyclate. The urethanes make up 90-95% of surface modifiers used for modifying recycled rubber due to their ease of implementation and adhesive characteristics.
For detailed information about the suppliers and users of surface modifiers, see the Rubber Blue Book and the Scrap Tire Directory.
For more information about this Best Practice, contact the CWC at (206) 443-7746, email email@example.com.
1. Struktol Technical Bulletin, “Struktol Vestol 28”.
2. US Patent to Fred Stark, Rubber Recovery Institute, on Surface Modification.
3. Trautman, John, Midwest Elastomers, P.O. Box 412, Wapakoneta, OH.
4. Wasko, Joe, Struktol Co., 201 E. Steels Corner Road, Stow, OH.
5. Fesus, Ed, Goldsmith & Eggleton, 300 First Street, Wadsworth, OH.
6. Smith, Fernly, President, ETA, 3862 The Ridge, Port Clinton, OH.
7. See Best Practices on Bonding Agents, Adhesives, and Binders.