DOWSIL™ EA-3838 2-Part Fast Silicone Adhesive

DOWSIL™ EA-3838 is a two-part, fast, room temperature curing, thixotropic, silicone adhesive. The product has been developed to show good, durable adhesion to a wide range of clean substrates including plastics, metals and glass.

DOWSIL™ EA-3838 Fast Adhesive has been developed to provide durable adhesive bonding and sealing for components which exhibit different thermal expansion rates, and /or where fast homogeneous cure throughout the adhesive cross section and an early adhesion development is needed.

Applications

• Automotive and automotive electronics assembly: Display bonding, general maintenance sealant, bond and seal housings
• Appliances manufacturing: bonding glass to metal, glass to painted metal or glass to plastic in ovens, refrigerators and small home appliances
• Industrial: Wind turbine sealant, general industrial sealing, gasketing and bonding applications
• Aerospace: Cargo door seal, general maintenance sealant, light sealant, edge sealant

Features

• Two-part, non-corrosive, neutral, alkoxy cure adhesive/sealant
• Fast and homogeneous cure in depth and early adhesion development at room temperature
• Non self-leveling, paste consistency
• Fast cure allows rapid handling of bonded components and a fast assembly process
• Good, durable adhesion to a wide variety of substrates
• Excellent weathering and U.V. resistance
• Excellent temperature stability: -50°C to 180°C

Properties

DOWSIL™ EA-3838 Fast Adhesive Base, Black: As Supplied

• Appearance Black viscous liquid
• Specific Gravity 1.34
• Viscosity (1 s -1 ) Pa.s 350.000–450.000
• Viscosity (10 s -1 ) Pa.s 150.000–200.000

DOWSIL™ EA-3838 Fast Adhesive Catalyst: As Supplied

• Appearance White paste
• Specific Gravity 1.60
• Viscosity (1 s -1 ) Pa.s 550.000–700.000
• Viscosity (10 s-1) Pa.s 75.000–100.000

DOWSIL™ EA-3838 Fast Adhesive: As Mixed by 2:1 (Base:Catalyst) Volume Ratio

• Appearance Black non-slump paste
• Snap Time (25°C, 50% R.H.) minutes 2–3
• Tack-free Time (25°C, 50% R.H.) minutes 5–8
• Vertical Flow mm/60 sec < 2

DOWSIL™ EA-3838 Fast Adhesive: As Mixed by 4:1 (Base:Catalyst) Volume Ratio

• Appearance Black non-slump paste
• Snap Time (25°C, 50% R.H.) minutes 4–6
• Tack-free Time (25°C, 50% R.H.) minutes 13–18
• Vertical Flow mm/60sec < 2

DOWSIL™ EA-3838 Fast Adhesive Properties After Full Cure, 2:1 by Volume Ratio – 7 Days at 23°C – Measured on 2 mm Sheets

• Durometer Hardness Shore A 40
• Tensile Strength MPa > 1.5
• Elongation at Break % > 250
• Early Adhesion via Lap Shear
• Lap Shear Strength Build Up, 2 mm Adhesive Thickness
• Glass / Stainless Steel
  • @ 15 Minutes   ≥ 0.5 MPa
  • @ 60 Minutes  0.7 MPa
  • @ 24 Hours 1.0 MPa
  • @ 7 Days 1.4 MPa

Adhesion via Lap Shear – 7 days at 23°C

• 0243 ASTM D 1002 Lap Shear Strength, 2 mm Adhesive Thickness
  • Glass / Stainless Steel, Steel, Galvanized Steel MPa 1.4
  • Glass / Aluminum, Eloxal Coated Aluminum MPa 1.2
  • Glass / PC, PA  1.2 MPa
  • Glass / ABS, PBT  1.0 MPa
• 1007 M Cohesive Failure
  Glass / Stainless Steel, Steel, Galvanized Steel % 100 / 100
  Glass / Aluminum, Eloxal Coated Aluminum % 100 / 100
  Glass / PC, PA % 100 / PC:50, PA:100
  Glass / ABS, PBT % 100 / 100

How to Use

Mixing

The adhesive is designed to be used in a mixing ratio between 2 parts base: 1 part catalyst by volume, (or 1.7 parts Base: 1 part Catalyst by weight) and 4 parts base: 1 part catalyst by volume, (or 3.4 parts Base: 1 part Catalyst by weight). Other mixing ratios between these limits can be used but Dow should be consulted prior to use. Suitable meter/mix equipment should be equipped with gear or piston metering pumps for base and catalyst, and a suitable static or a dynamic mixer.

The presence of light-colored streaks, or marbling, indicates inadequate mixing. Automated airless dispense equipment can be used to reduce or avoid the need to de-air.

Curing Conditions

The adhesive cures at room temperature and develops adhesion rapidly to glass, plastic and metal substrates. The surfaces to be bonded should be clean, and free of any extraneous matter, dust or dirt. Adhesion is normally good to most substrates without the use of a primer, or of other surface activation methods. If desired, adhesion may be enhanced via use of flame or plasma treatment or corresponding primers on the surfaces to be bonded. The cure and adhesion strength can also be further accelerated by the application of moderate heat up to 60°C.

Temperature, Hot and Humid Resistance

DOWSIL™ EA-3838 Fast Adhesive shows good adhesive resistance to hot and humid conditions, for example 7 days in water at 70°C.

DOWSIL™ EA-3838 Fast Adhesive shows good adhesive resistance up to 180°C and can resist higher temperatures for short-term peaks.