Adhesives for LSE substrates. Joining Methods Non structural (
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Transcript of Adhesives for LSE substrates. Joining Methods Non structural (
Adhesives for LSE substrates
Joining Methods
Non structural (<1000 psi OLS) Adhesives
Hot melts (3M Jet-meltTM 3731) Spray adhesives (3M Hi-Tack 76 Spray
Adhesive) PSA Tapes (3M 300LSE High Strength
Laminating Adhesive or Double-Coated Tape)
Re-closable fasteners Hook & loop (3M ScotchmateTM SJ-3506 and
SJ-3507)
Joining Methods
Structural (>1000 psi OLS) Adhesives
Traditionally, surface preparations (priming, etching, flame treatment) that alter the surface energy are necessary (3M Scotch-weldTM DP-420 after flame treating)
3M Scotch-weldTM DP-80XX (other than light cleaning - no surface prep necessary)
Mechanical joining Machine screws ( nut and bolt or threaded insert) Self threading screws/nuts
Other Joining Methods
Snap fit Hook/beam,annular, ball and socket,
Press fit Heat staking/ hot air cold staking Radio frequency dielectric heating Ultrasonic welding Multi-shot molding
Adhesive & Cohesive Strength
Cohesion – Internal strength of material
Substrate
Substrate
Adhesive
Adhesion – Force between dissimilar surfaces
Substrate
Substrate
Adhesive
Stresses on a Joint That Can Lead to Bond Failure
Shear Tensile
PeelCleavage
Joint Design
Designing the joint to minimize peel or cleavage stresses on the bond line and maximize tensile, shear or compressive stresses is desirable
Improving joint design to accommodate applied stress
Bonding Process
WGT
Surface prep (cleaning) Applying liquid adhesive
Closing up the bond Apply pressure during cure (clamping)
Bonding Process
Adhesive Wetting
c-lv
Co
nta
ct A
ng
le
Qliquid ofenergy surface
substrate ofenergy surface critical
)(1cos
Equation sZisman'
lv
c
lvcbθ
Effects of Surface Treatment on Polyethylene
30
32
34
36
38
40
42
Untreated Exposed to UVLight
Flame Treated Exposure to UVLight in presence
of solvent
Etched inchromic acid
Treatment
Surface Energy (mN/sq.m.)
Surface Treatment
Key Performance Characteristics of a Structural Adhesive
Bond making properties Usability in manufacturing process
Degree of surface preparation necessary Open time (work-life) Time to handling strength (50 psi OLS) Cure conditions (temperature, pressure) Viscosity (non sag, pump ability) Delivery equipment
Key Performance Characteristics of a Structural Adhesive
Cured bond properties Environmental resistance
Thermal Shock Weathering
Chemical resistance Solvents Moisture
Substrate Processing Effects
Processing of substrate impacts the bulk and interfacial properties of the substrate
Adhesive performance is coupled not only to the material type but also to the process conditions used to make the substrate
3M Scotch-weldTM DP-8005
2 part – 10:1(B:A) mix Base (B) - acrylic Accelerator (A) - amine
Density B = 8.2 lbs/gal A = 8.9 lbs/gal
Viscosity B = 23,000 cps nominal A = 45,000 cps nominal
Open time (work life) 2-3 minutes @ 23C
Time to handling strength
2-3 hrs @23C 15 minutes @ 80C
Full cure time 8 hrs @ 23C 1 hr @80C
3M Scotch-weldTM DP-8005
Mechanical properties Shore D hardness =
55 Peak strain = 5.3 % Peak stress = 1889
psi Thermal properties
Tg = 34-38 C (DSC @ 10c/min.)
CTE = 6.6 ppm/degC
3M Scotch-weldTM DP-8005
Overlap Shear 3M Scotch-weldTM DP-8005 On Various Substrates
0
500
1000
1500
2000
2500
3000
Substrate
Stre
ngth
(psi
)
Translucent Black
SY SY
SY
SYSY
SY SY SYAF
SF
SF SF
SF
CF
CF
MM
SY = Substrate yieldSF = Substrate failureAF = Adhesive failureCF = Cohesive failureMM = Mixed failure
3M Scotch-weldTM DP-8005
Environmental & Chemical Exposure of 3M Scotch-weldTM DP-800514 days exposure at 75 F (unless another temp is noted) on HDPE
0
200
400
600
800
1000
1200
Contro
l
160F
/100
% R
H
160F
/Wat
erSoa
k
10%
NaO
H
16%
HCl
20%
Ble
ach
IPA
Antifr
eeze
Gasol
ine
Diesel
Fuel
Toluen
e
Chemical
OL
S (
psi
)
Translucent Black
SY SY SY SY SY SYMix Mix Mix
CF CF
SY = Substrate yieldCF = Cohesive failureMix = Some of both
3M Scotch-weldTM DP-8005
Similar to 3M Scotch-weldTM DP-8005 with regard to performance characteristics on LSE substrates
Longer work life – 10 minutes Slightly shorter time to handling
strength – Just under 2 hours More flexible – better peel
performance Less sensitive to process
history of substrate
3M Scotch-weldTM DP-8010
• Bonding Polypropylene with polyethylene
3M Scotch-weldTM DP-80XX Applications
3M Scotch-weldTM DP-80XX Applications
• Dashboard
• Building industry
Application:House connectors
Bonding a flexible pipe (PE) with a rigid one (stainless steel)
3M Scotch-weldTM DP-80XX Applications
• Electronics
3M Scotch-weldTM DP-80XX Applications
Description:
A 100% solids, high heat resistant adhesive that bonds to a variety of substrates including polyethylene, polypropylene and many other plastics.
3MTM Jet-MeltTM
Polyolefin Bonding Adhesive 3731
3MTM Jet-MeltTM
Polyolefin Bonding Adhesive 3731
Features:• Solvent free, 100% solids• High temperature resistance• Bonds well to polyolefin based
plastics• Light tan color• Fast setting
3MTM Jet-MeltTM
Polyolefin Bonding Adhesive 3731
Typical Physical Properties: Color : Light Tan Specific Gravity: 0.92 Flash Point (C.O.C.): 525°F (273°C) Viscosity @ 375°F(1) (191°C): 12,000
cps Bonding Range - 1/8" (Bead sec. (3) ):
25-30 seconds Impact Resistance (Inch lbs @ 72°F): 80
3MTM Jet-MeltTM
Polyolefin Bonding Adhesive 3731
Heat resistance:
3MTM Jet-MeltTM
Polyolefin Bonding Adhesive 3731
Overlap Shear Strength:
Future R&D Directions
Longer open times Faster cure times
Inherent in the product External techniques for accelerating
Adhesive performance Adhesive Bonding process Substrate (material and processing
history)