826 A Covercoat Adhesive Designed for Use Over Primers

Rubber to Metal Bonding Adhesive 826

(Equivalent to Chemlok 6100, Megum 538)

1. Application

826 is a covercoat adhesive designed for use over primers. It is formulated without heavy metals and composed of a mixture of polymers, organic compounds and mineral fillers dissolved or dispersed in an organic solvent system. This adhesive system will bond compounds based on natural rubber (NR), polyisoprene (IR), styrene-butadiene (SBR), polybutadiene (BR), polychloroprene (CR), nitrile (NBR), butyl (IIR) and EPDM polymers to metal.

826 is formulated to meet VOC requirements under the China regulatory specification GB33372-2020.

2. Characteristics

• Easy to Apply – applies easily by spray, dip or brush methods.

• Convenient – requires only a single coat for most applications, reducing labor, solvent usage, inventory and shipping costs.

• Environmentally Resistant – provides excellent resistance to various elements.

• Environmentally Recommended – formulated without heavy metals.

• Process Compatible – accommodates a wide range of processing conditions at moderate temperatures, including extended prebake.

  
  

3. Physical Properties

 Appearance: Black Liquid

Viscosity, cps @ 25°C (77°F) Brookfield LVT Spindle 2, 30 rpm: 300-1000

Density(kg/m3): 950 – 1050

Solids Content by Weight, %: 21-24

Flash Point (Seta), °C: 25-28

Solvents: Xylene, Dimethyl Carbonate

4. Applying 826

• Surface Preparation – Thoroughly clean metal surfaces prior to adhesive application. Remove protective oils, cutting oils and greases by solvent degreasing or alkaline cleaning. Remove rust, scale or oxide coatings by suitable chemical or mechanical cleaning methods.

• Chemical Cleaning

Chemical treatments are readily adapted to automated metal treatment and adhesive application lines. Chemical treatments are also used on metal parts that would be distorted by blast cleaning or where tight tolerances must be maintained. Phosphatizing is a commonly used chemical treatment for steel, while conversion coatings are commonly used for aluminum.

• Mechanical Cleaning

Grit blasting is the most widely used method of mechanical cleaning. However, machining, grinding or wire brushing can be used. Use steel grit to blast clean steel, cast iron and other ferrous metals. Use aluminum oxide, sand or other nonferrous grit to blast clean stainless steel, aluminum, brass, zinc and other nonferrous metals.

For further detailed information on surface preparation of specific substrates, refer to Exceed Adhesives application guide. Handle clean metal surfaces with clean gloves to avoid contamination with skin oils.

Mixing – Thoroughly stir 826 before use, and agitate sufficiently during use to keep dispersed solids uniformly suspended. Use an air-driven or other explosion-proof mixer for agitator drums or on other smaller containers. If dilution is needed, use xylene or toluene.

Applying – Apply 826 adhesive by brush, dip, spray or any method that gives a uniform coating and avoids excessive runs or tears. Spray and dip application methods are recommended as they better control uniformity and dry film thicknesses.

When using 826 as a one-coat adhesive, the dry film thickness should be maintained at 20.3-25.4 micron (0.8-1.0 mil), particularly if the bonded assembly is likely to be exposed to severe environments. When used as a covercoat over a primer, the dry film thickness of 826 should be 15.2- 20.3 micron (0.6-0.8 mil).

• Spraying

Dilute adhesive to a Zahn Cup #2 viscosity of approximately 24 seconds. This equates to approximately 3 parts adhesive to 2 parts solvent.

• Dipping

Use full strength. As a one-coat adhesive, a single dip application of 826 usually results in a dry film thickness of 20.3-25.4 micron (0.8-1.0 mil). When used over a primer, a single dip of 826 adhesive is sufficient to provide a total dry film thickness of 25.4-30.5 micron (1.0-1.2 mil).

Curing – 826 can be used in compression, transfer and injection molding procedures. Ideal bonding conditions involve a minimum amount of time between loading the adhesive coated parts and elastomer vulcanization. However, 826 will resist moderate prebake times without affecting bond performance.

5. Shelf Life/Storage

Shelf life is 6 months from date of shipment when stored at 21-27°C (70-80°F) in original, unopened container. Do not store or use near heat, sparks or open flame.

6. Packing

3.5kg/drum; 18kg/drum