DOWSIL™ EA-3838 Fast Adhesive

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Faster assemblies at room temperature with new, very fast cure DOWSIL™ EA-3838 Fast Adhesive

 

Global adhesive and sealant market growth

The global adhesives and sealants market size is expected to reach USD 82.4 billion by 2025. This corresponds to a CAGR of 5.6% during the forecast period.

High demand for adhesives and sealants comes from different industries:

  • Construction
  • Assembly
  • Automotive
  • Appliance
  • Aviation

 

Major growth trends

DOWSIL™ EA-3838 Fast Adhesive_,major growth trends

 

Addressing the needs: Improving profitability and reducing carbon footprint

DOWSIL™ EA-3838 Fast Adhesive has been developed for manufacturers of appliances, automotive electronics, lighting, aerospace and beyond, willing to improve their profitability while reducing their costs and carbon footprint.

 

Silicone cure technologies

DOWSIL™ EA-3838 Fast Adhesive_silicone cure technologies

 

Silicones product technologies

DOWSIL™ EA-3838 Fast Adhesive_silicone product technologies

 

Seadling and bonding: Room-Temperature Vulcanization

Package / Delivery / Storage

Typical storage conditions of 1-part RTV sealants: When stored at or below 30°C (86°F) in the original unopened containers, this product has a usable life of 12 months from the date of production.

Storage conditions of SILASTIC™ Q3-3636 Adhesive Catalysts, 2-part RTV: When stored at or below 25°C in the original unopened containers, SILASTIC™ Q3-3636 Adhesive Catalysts have a usable life of 5 months from date of production.

DOWSIL™ EA-3838 Fast Adhesive_package

 

Dispensing / Application

DOWSIL™ EA-3838 Fast Adhesive_,dispensing

1-Part RTV equipment is less complex as no mixing or heating tunnels are required. This is because short-term heat has no significant effect on cure speed.

BUT a storage area is needed for curing finished parts. Time in storage area depends on:

  • Temperature and humidity
  • Part design
  • Follow-up processes

Mix ratio of current 2-part RTV sealants is 100:14 by weight (100:17 by volume). Uneven mix ratio:

  • Requires different pumps to meter correctly
  • Requires precise mix ratio control
  • Means that no commercial cartridge system is available

 

Open-time / Tack-free time

1-Part RTV
Cure rate – skin-over / tack-free time by fingertip contact
Abstract: The skin-over time, a measure of cure rate, is defined as the time in minutes required for a curing material to form a non-tacky surface film.

2-Part RTV
Working time – snap technique
Abstract: This technique measures the length of time it takes for a room-temperature vulcanizing material to show the first sign of rubberiness after the material is completely formulated and exposed to normal curing conditions

Cure rate – skin-over / tack-free time by polyethylene contact
Abstract: The skin-over time (measure of cure rate) is defined as the time in minutes required for a curing material to form a non-tacky surface film. This method uses polyethylene film contact to determine the non-tacky characteristic and can report pass/fail if the skin-over time is specified as a minimum.

 

Inline pressure leak test

The inline pressure leak test can be done with Time Worker from TM Electronics, Inc., in combination with a metal jig according to ASTM F2523-13. The jig has a gap of 1 mm height and 8 mm width. A small bead of material was applied all around the flange of the metal jig. Right after application of the material, the jig was assembled and the test was started.

  • Dow lab leak test parameter: Charge 6.5 kPa for 80s -► hold 6.5 kPa for 5s -► test
  • Test time: Hold 6.5 kPa for 120s
  • Pass criteria: Pressure decay max. 0.1 kPa
  • Test parameters are application and customer specific.

DOWSIL™ EA-3838 Fast Adhesive_inline pressure leak test2 DOWSIL™ EA-3838 Fast Adhesive_inline pressure leak test

 

Cure Profile

1 – Part RTV

DOWSIL™ EA-3838 Fast Adhesive_cure profile1

2 – Part RTV

DOWSIL™ EA-3838 Fast Adhesive_cure profile2

 

Adhesion development

DOWSIL™ EA-3838 Fast Adhesive_adhesion development

 

Typical properties

DOWSIL™ EA-3838 Fast Adhesive_typical properties

 

Special properties

Heat Resistance at 200ºC

DOWSIL™ EA-3838 Fast Adhesive_special properties heat resistance

 

Heat Resistance by product

DOWSIL™ EA-3838 Fast Adhesive_special properties heat resistance1

Dynamic mechanical thermal analysis (DMTA)

DOWSIL™ EA-3838 Fast Adhesive_dynamic mechanical thermal analysis

 

Recap

DOWSIL™ EA-3838 Fast Adhesive_recap

 

Technical introduction to DOWSIL™ EA-3838 Fast Adhesive

General product information

DOWSIL™ EA-3838 Fast Adhesive_general product information

  • A 2-part, alkoxy, RTV material that develops early primerless adhesion on various substrates, with a very fast cure speed
  • This adhesive consists of a black base and a white catalyst
  • It has a variable 2:1 to 4:1 volumetric mixing ratio, non-flammable components, and an up to 12-month shelf life for both components
  • It will be commercially available in pail, drum and dual-cartridge kit packaging

 

Mechanical properties versus competition

DOWSIL™ EA-3838 Fast Adhesive_mechanical properties versus competition

 

Cure speed and early adhesion development

DOWSIL™ EA-3838 Fast Adhesive_cure speed

 

Dispensing / Application; 1- and 2-part RTV

DOWSIL™ EA-3838 Fast Adhesive_dispensing and aplication

 

  • Eliminates the need for oven acceleration, but can be accelerated through heating tunnels – max 60°C
  • Elimination of heat decreases energy consumption and improves sustainability
  • Faster cure makes earlier inline pressure leak testing possible, reducing cycle time drastically
  • Variable mixing ratio provides flexibility to meet a wide range of open times– cure speeds

 

Adhesion development after full cure

DOWSIL™ EA-3838 Fast Adhesive_adhesion development after full care

Typical break pattern on clean surfaces without any surface pretreatment is cohesive failure, but adhesion depends on the specific properties of the surface.

 

Potential Mixing Ratios / Version

DOWSIL™ EA-3838 Fast Adhesive_potential mixing ratios

 

Heat resistance

DOWSIL™ EA-3838 Fast Adhesive can withstand temperatures up to 180°C and even shorter peaks at above temperatures.

When larger adhesive surfaces are subject to atmospheric contact (O2), resistance at higher temperatures might be negatively affected.

DOWSIL™ EA-3838 Fast Adhesive_heat resistance 1t 180

 

Package / Delivery / Storage Conditions

When stored at or below 30°C in the original unopened containers DOWSIL™ EA-3838 Fast Adhesive Catalyst has a usable life of 12 months from date of production.

DOWSIL™ EA-3838 Fast Adhesive_package1

 

Final recap

DOWSIL™ EA-3838 Fast Adhesive_final recap

 

Applications – Household appliances

DOWSIL™ EA-3838 Fast Adhesive_applications

 

Applications – Other markets

DOWSIL™ EA-3838 Fast Adhesive_applications other markets

 

Packaging

DOWSIL™ EA-3838 Fast Adhesive_packaging

 

Conclusions

DOWSIL™ EA-3838 Fast Adhesive is a 2-part, alkoxy RTV silicone adhesive aimed at applications where a strong bond is needed along with a fast cure speed and early primerless adhesion development.

Features and benefits:

  • Fast curing time
  • Early primerless adhesion development
  • Improved adhesion to several substrates
  • Improved shelf life to 12 months
  • Easy & flexible mixing ratio (2:1, 3:1, 4:1)
  • Also available in cartridges

Main market: Appliance
Secondary markets: Aviation, automotive, lighting and industria

 

Source: Dow fast adhesive presentation

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If you have a problem with industrial adhesives, sealants, lubricants or electronic protection products and require advice, you can contact our technical support service. Our team can help you to optimize your processes and applications.

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