Butyl Rubber

What is Butyl Rubber?

Butyl rubber, also known as isobutylene-isoprene rubber (IIR), is a versatile, general purpose, synthetic rubber and a copolymer of isobutylene with isoprene. Butyl rubber is produced by polymerization of about 98% of isobutylene with about 2% of isoprene. It is ideal for shock absorption, offers particularly low gas and moisture permeability, exceptional resistance to heat, weather, ozone, abrasion, tearing, chemical corrosion and much more.

Butyl rubber is impermeable to air, so it is useful in many applications requiring an airtight rubber. Butyl’s strength, flexibility, low gas permeability and airtight characteristics mean it is also ideal for high pressure or vacuum sealed applications. The first widespread application of butyl rubber, however, was tire inner tubes. This application is still central for butyl rubber to this day.

Butyl is an incredibly versatile synthetic rubber. However, it is not recommended for use in applications involving contact with petroleum oils. Continue below for more properties and advantages of Butyl:

Properties of Butyl Rubber

  • Isobutylene-isoprene rubber (IIR)
  • ASTM D-2000 Classification AA, BA, CA (Standard Classification System for Rubber Products in Automotive Applications)
  • Chemical Definition Isobutylene Isoprene Rubber

Butyl Rubber Processing

  • Transfer Molding
  • Injection Molding
  • Compression Molding

Physical & Mechanical Properties

  • Durometer or Hardness Range: 40 – 90 Shore A
  • Tensile Strength Range: 500 – 3,000 PSI
  • Elongation (Range %): 300% – 850%
  • Abrasion Resistance: Fair to Good
  • Adhesion to Metal: Good
  • Adhesion to Rigid Materials: Fair – Good
  • Compression Set: Fair – Good
  • Flex Cracking Resistance: Good – Excellent
  • Impact Resistance: Good
  • Resilience & Rebound: Fair – Good
  • Tear Resistance: Good
  • Vibration Dampening: Excellent

Chemical Resistance

  • Dilute Acids: Good – Excellent
  • Concentrated Fair: – Excellent
  • Organic Acids (Dilute): Good
  • Organic Acids (Concentrated): Fair to Good
  • Inorganic Acids: Good
  • Alcohols: Good – Excellent
  • Aldehydes: Good
  • Dilute Alkalies: Good – Excellent
  • Concentrated Alkalies: Good – Excellent
  • Amines: Good
  • Animal & Vegetable Oils: Good – Excellent
  • Brake Fluids, Non-Petroleum Based: Good
  • Diester Oils: Poor – Good
  • Alkyl Phosphate Esters: Good – Excellent
  • Aryl Phosphate Esters: Excellent
  • Ethers: Poor – Fair
  • Aliphatic Hydrocarbon Fuel: Poor
  • Aromatic Hydrocarbon Fuel: Poor
  • Extended Fuel (Oxygenated): Poor
  • Halogenated Solvents: Poor
  • Hydrocarbon, Halogenated: Poor
  • Ketones: Poor – Excellent
  • Lacquer Solvents: Fair – Good
  • LP Gases & Fuel Oils: Poor
  • Mineral Oils: Poor
  • Oil Resistance: Poor
  • Aromatic Petroleum: Poor
  • Non-Aromatic Petroleum: Poor
  • Ammonia Refrigerant: Good
  • Refrigerant Halofluorocarbons: R-12, R-13
  • Refrigerant Halofluorocarbons with Oil: Poor
  • Silicone Oil: Poor
  • Solvent Resistance: Poor

Thermal Properties

  • Low Temperature Range: 70ºF to – 40ºF
  • Minimum for Continuous Use (Static): 60ºF
  • Brittle Point: 90º F to – 50° F
  • High Temperature Range: +250º F to +300ºF
  • Maximum for Continuous Use (Static): +300ºF

Environmental Performance

  • Colorability: Good
  • Flame Resistance: Poor
  • Gas Permeability: Good
  • Odor: Good
  • Ozone Resistance: Excellent
  • Oxidation Resistance: Excellent
  • Radiation Resistance: Poor – Good
  • Steam Resistance: Good – Excellent
  • Sunlight Resistance: Excellent
  • Taste Retention: Fair – Good
  • Weather Resistance: Excellent
  • Water Resistance: Good – Excellent

Applications of Butyl Rubber

  • Shock mounts
  • Sealant for rubber roof repair
  • Tubeless tire liners
  • Inner tubes
  • Stoppers for glass bottles, medicine bottles, and pharmaceuticals
  • Used in sealants and adhesives
  • Tank Liners
  • Sealants, hoses, and mechanical goods
  • Adhesives
  • Agricultural chemicals
  • O-rings
  • Electrical fluids
  • Personal care products
  • Pigment concentrates
  • Rubber & Polymer modification

*The usual working temperature range of butyl products is -50°C (-25°C) to +120°C. Need to clarify F and C temps.

What We Do!

Comdaco offers over 55 years of experience in many manufacturing disciplines.