Cover coat adhesive for bonding EPDM and Butyl to Metals.

Introduction

Polyloc 330 is an adhesive system for bonding a variety of unvulcanised rubbers including EPDM and Butyl to metals during the vulcanisation of the elastomer. Used as a cover coat with Polyloc P as primer, this adhesive system produces bonds that are outstandingly resistant to various kinds of environmental conditions and corrosion, and capable of withstanding extreme static and dynamic stresses.

Polyloc 330 is used in the manufacture of various industrial items used in the automobile, railway and machine industry like profiles, auto tube valves, printing/industrial rollers, rubber lining, and other rubber to metal bonded products.

Properties of Polyloc 330

Composition	Organic polymers and fillers dissolved in organic solvents.
Color	Black
Solid Contents	18 ~ 21%
Density	0.96 ~ 1.02
Diluents	Toluene or Xylene
Viscosity (20oC)	400 to 800 cps
Shelf Life	1 year
Flash Point	15.5 dC

Preparation of Metal Surface

This is the most critical and important step for any rubber to metal bonding application. The metal surface should be properly cleaned of all contaminants such as oil, rust, scales, dirt, etc. by suitable mechanical and/or chemical methods.

Grit/sand blasting, and wire cloth abrading are the usual mechanical methods of metal preparation, and give excellent results. Chemical treatment of the metal surface by phosphatising results in a highly corrosion resistant and bondable surface. The general steps are: Water rinse - Acid pickle - Water rinse - Phosphatise - Water rinse - Chromate rinse.

Application of the Adhesive

Polyloc 330 has to be stirred thoroughly for 10 minutes before and intermittently during use. The adhesive may be applied by dip, spray or brush. The application of a thin and uniform coating of the bonding agent, free from excessive runs, tears or fatty edges is an essential condition for optimum bonding results.

It takes 30 minutes for Polyloc 330 to dry at room temperature. For faster drying, ovens can be used, although very high temperatures should be avoided. Care has to be taken to ensure that the primer film has dried fully before applying the cover coat.

Vulcanisation / Bonding

Polyloc 330 allows good bonds to be obtained by various curing methods. Normal vulcanising methods including press curing and autoclave can be used to get excellent bond results. Best results are obtained at curing temperatures between 140oC and 170oC.

The adhesive shows no deterioration when subjected to reasonable pre-baking period which generally occur in multi-cavity molds. However it is advisable to load the adhesive coated metal parts and fill the cavity with rubber compound in the minimum amount of time.

Post Vulcanisation Treatment

Basic care should be taken in removing the hot bonded parts from the molds so as to prevent any damage to the bond. The bonds will gain their full strength after cooling and maturing for 10 - 12 hours.

Cautionary Information

This product is meant for industrial use only. It contains highly volatile aromatic solvents; keep product away from heat, direct sunlight, and open flame. Vapors may be harmful and prolonged breathing of vapors and mists should be avoided. May be harmful or fatal if swallowed.