sign in sign up
<<
Home , Silicone rubber

- HOW TO BOND ALL TYPES OF RUBBER --

BACKGROUND

One of the most common materials incorporated into the design of products today is rubber. chemistry is an exploding technology. Because of this, the selection of an adhesive to bond rubber is becoming more complex. Therefore, the purpose of this report is to bring you up to date on the types and characteristics of rubber and to provide you with some guidelines in the selection of an adhesive for a particular type of rubber. There are three basic sources of rubber; natural, reclaim, and synthetic. Elastomer chemistry breaks these down into family types. Each family type can be further broken down into grades. Grades identify the quality or the properties within a family type. Listed below are the common names and chemical types of 15 different elastomer families: COMMON NAMES CHEMICAL TYPE (NR) Natural Polyisoprene Reclaimed rubber Depends on type of scrap Acrylics Polyacrylic Butyl (11 R) Isobutylene-isoprene E P Rubber (EPR) Ethylene propylene Fluord Elastomer Fluorinated Hydrocarbon Hypalon Chlorosulfonated (CR) Chloroprene N it r i1 e ( N BR) Nitrile-butadiene Polybutadiene (BR) Polybutadiene Polysulfide Polysulfide Polyurethane Polyurethane-diisocyanate SBR (Formerly GR-S) Styrene-butadiene Polysiloxane (IR) Synthetic polyisoprene

LESS COMMON : Chlorobutyl Isobutylene-isoprene with chlorine - ABR Acrylate-butadiene NCR Nitrile-chloroprene PBR Pyridine-butadiene SIR Styrene-isoprene - Propylene oxide rubbers Propylene-oxide CHR Epichlorhydrin CHC Epichlorhydrin-ethylene oxide

Common Name: E.P. RUBBER (EPR) (EPDM TYPE) Chemical Type: Ethylene-Propylene E.P. Rubber is a "" of ethylene and propylene. When a third monomer diolefin is added, the end result if "EPT" rubber - Ethylene Propylene Terpol ymer. Relative Cost: Same as SBR rubber. Advantages Excellent , , weather, and heat resistance. - Good colour stability. Good dielectric qualities. High elasticity. Low cost. Disadvantages Poor resistance to aliphatic and halogenated hydrocarbons. Poor flame resistance. Poor tear resistance. Major Uses for E.P. Rubber Automotive weather stripping. Radiator hose, steam hose. Seals, snubbers, boots, dust covers. Bleach tubing, cable insulation. Sleeves, mounts, bumpers. Conveyer belting. Surface Preparation See page 18 - Use system 1. Enjay Chemical Company suggest the use of the following primer and adhesive systems for bonding E.P. Rubbers: Chemlock 0.05 Primer Lord Manufacturing Co. Chemlock EXA 60.40 Adhesive - T

E.P. Rubbers are relatively new products and have been found to be very difficult to bond.

7 -

Common Name: FLUORO ELASTOMERS Chemical Type: Fluorinated Hydrocarbon These types of elastomers are a copolymer of chlorotrifluoroethylene and vinylidene fluorine containing more than 50% fluorine by weight. Relative Cost: About 3000% more than SBR. Advantages Excellent resistance to corrosive fuming acids, strong bases, peroxides, solvents, oils, ozone, weathering, micro-organisms. - Low water absorption. Good electrical properties. Thermal stability to 440° F. Flame resistant. High Tensile strength and extensibility. Outstanding compression set. Disadvantages Poor dynamic properties at low temperatures. - Poor resistance to phosphates and diesters. Major Uses for Fluoro Elastomers Electrical connectors. Wire insulation. Tubing and hose. Protective clothing. Molded, calendered and extruded goods. Adhesives, coatings, sealers. Fuel cells and storage tank liners, a-rings, lip seals, shaft seals, Diaphragms. Surface Preparation Primer: B. F. Goodrich, "A-934-BX" and Dow Corning, "DOW Z-6020" are two - amino silane primers which have been found particularly effective for promoting adhesion during the of uncured stock. - Bonding Fluoro Elastomers The surface of a fluoro elastomer is very inert - similar to silicone, polyethylene, etc. Adhesives that have been found satisfactory for bonding cured stock are: Chemlock 607 Lord Manufacturing Co. 8

- -

Common Name: SILICONE Chemical Type: Polysilozane Silicone or gums, from which silicone elastomers are compounded, are manufactured by a complex series of chemical transformations starting from sand and alkyl or aryl halides. Relative Cost: About 1000% more than SBR Advantages -150° F to 600° F maintained. - Low compression set. Tasteless, odour free. Non sticking. Non staining, does not discolour. High degrees of ozone, aging, sunlight, chemical and electrical resistance. Disadvantages Affected by gasoline, oil, and degreaser solvents. - Low physical properties at room temperature. Major Uses for Silicone Elastomers Aircraft seals, O-rings, gaskets, bushings. Anti-icing hoses. Oxygen masks. Sparking plug boots. Wire cable insulation. Nursing bottle nipples. Surgical implants Sealers and adhesives. Surface Preparation See page 18 - Use system 2A Primer: Not required on the rubber stock but must be used on the other surface to be bonded. Primers for metal are:

Bonding Silicone Rubber The bond can only be made with silicone based adhesives such as: RTV C-319 Connecticut Heard Rubber Co. RTV 90 General Electric Co. RTV 60 General Electric Co. 16