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)