PRODUCT DESCRIPTION

　　LOCTITE® 3542 is a reactive hot-melt adhesive based on

　　polyurethane prepolymers. The adhesive is pressure sensitive

　　and provides a high initial strength instantly after joining the

　　parts. Additionally it has a long open time to be suitable for

　　automatic or manual assembly line.

　　TYPICAL PROPERTIES OF UNCURED MATERIAL:

　　Colour: Transparent when molten,

　　light ivory after cooling

　　Odour: Weak

　　Density:

　　STM735 1.15􀁲0.05g/cm3

　　Solids: 100%

　　Viscosity:

　　Brookfield Thermosel,

　　Spindle 27

　　4000-7000mPa.s @100degC

　　Open time1: 2-4 min

　　Preheating temperature

　　and time 90 to 100 degC for 20-30 mins

　　Application Temperature: 90 to 110 degC

　　1:The bonding range of a 1mm bead of molten adhesive on

　　substrate. Open time is based on a room temperature

　　environment. Higher temperature will lengthen the open times

　　while lower environmental temperatures will shorten the open

　　times.

　　TYPICAL PROPERTIES OF CURED MATERIAL:

　　Coefficient of Thermal Expansion 2 (um/mK.)

　　STM767 168.2

　　Thermal Conductivity 2 (W/mK)

　　STM774 0.318

　　Specific Heat Capacity 2 (KJ/(Kg.K)), 26C

　　STM827 2.7

　　Elongation 3 (%)

　　STM708 >400

　　Elastic modulus 3 (MPa)

　　STM708 >200

　　Tensile strength 3 (Mpa)

　　STM708 >8

　　2: cured for 7 days, curing condition is 24-30C, 50%-70%

　　3: cured for 9 days, curing condition is 20-25C, 60%-70%

　　Pretreatment

　　The bonding surfaces must be clean, dry and free of oil and

　　grease. Substrate temperature should not fall below 20degC

　　during application. Lower temperatures will lead to early

　　solidification of the adhesive and thus to a reduced open time,

　　possibly the adhesive might even flake off. The substrates

　　may be preheated if necessary.

　　Application

　　LOCTITE® 3542 can be applied from heating cartridge guns,

　　from usual syringe type melting equipment. At longer rest

　　periods, melting and application temperatures should be

　　decreased. Longer exposure to higher temperatures can lead

　　to a viscosity increase.

　　Curing

　　LOCTITE® 3542 cures exclusively by moisture and gains its

　　final strength in 1-5 days, but exhibits high handling strength

　　instantly after joining.

　　Curing is a chemical reaction depending on the following

　　parameters:

　　- Humidity in the rooms of application and storage

　　- Mositure content on the substrates

　　- Permeability of the substrates to be bonded

　　- Application volume / layer of the adhesive film