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HYDROCARBON SPECIALTY CHEMICALS
tel : (33) (0) 3 44 55 68 05
fax : (33) (0) 3 44 55 67 06
http://www.crayvalley.com
Wingtack Hydrocarbon Resins in
Pressure Sensitive Adhesives
Application Guide
L105-1 _ January 2010
PSA GENERALITIES
Definition of a PSA
Chemistries
Formulating Styrene Block Copolymers
Coating process
Testing PSA
Wingtack tackifying resin range
Applications & orientation formulations
Labels
Tapes
Films
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Definition
A PSA (Pressure Sensitive Adhesive) is an adhesive that remains
permanently sticky and can adhere with only a light pressure (finger
pressure).
Synonymous:
Self-adhesive
Permanently tacky
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Chemistries
A PSA can be based on different chemistries and in various solvents:
Water based
Solvent based
Hot Melts
(WB)
(SB)
(HM)
X
X
X (UV)
X
X
X
X
Acrylic copolymers
Styrene block copolymers (SBC)
Rubber-based (natural or synthetic)
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X
4
Chemistries
Acrylic based PSA (WB or SB)
The acrylic itself gives the properties: no need to formulate
Optional formulation: tackifying resin, antifoam, wetting agent…
Styrene block copolymers & rubber-based PSA (WB, HM or SB)
Must be formulated with tackifier: SBC, NR and SBR are not tacky (PSA)
by themselves. Formulation comprises at least:
a polymer (SBC, NR or SBR)
a tackifying resin
a plasticizer
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Formulating SBC based PSA
Styrene Block Copolymers
Incompatible blocks of hard (poly-styrene, Tg=95°C) and soft (polyisoprene, Tg=- 60°C or poly-butadiene, Tg=- 90°C) pol ymers → SIS or SBS
Different architectures
Soft phase
PS
Diblock
Star / Radial
Hard phase
PS
PI or PB
PS
PS
PS
PS
Triblock
PS
Global structure of SBC
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Formulating SBC based PSA
Dynamical Mechanical Analysis of a SIS block copolymer showing
the 2 incompatible phases:
• The soft / elastomer phase made of poly-isoprene (Tg# - 60°C) giving TACK
• The hard phase made of poly-styrene (Tg# 95°C) givi ng COHESION
G'
Tanδ
Tg (PI)
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Tg (PS)
7
Temperature (°C)
Formulating SBC based PSA
Formulation contains at least:
Styrene Block Copolymer
to choose depending on the final application
Tackifying resin
to choose compatible with the soft phase of the SBC in order to decrease G' modulus to meet
Dahlquist's criteria
Plasticizer
in general: paraffinic or naphthenic oil
Log G‘ et Log G’’
POLYMER
POLYMER + RESIN
10
10
10
9
99
8
88
7
77
6
66
5
55
4
44
3
33
Temperature
Temperature
L105-1 _ January 2010
non PSA
Critè re de
Dahlquist
Dahlquist
criteria
8
PSA
Formulating SBC based PSA
Two different types of resins can be added:
WINGTACK aliphatic tackifying resin:
Low Molecular weight
G’ and soft phase viscosity
Compatible with the soft phase
Dahlquist criterium ok
G’ < 105
Soft phase Tg
High Tg (40 – 50 °C)
WINGTACK = Tackifying resin
NORSOLENE S 155 aromatic reinforcing resin:
Low Molecular weight
Viscosity (PS)
Tg (PS) remains high
Compatible with the PS phase
High Tg (95 - 100 °C)
High SP NORSOLENE = Reinforcing resin
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Formulating SBC based PSA
Tackifying resin : effect on Modulus (G’) and Tg
G’ (Pa)
Neat Polymer
+ Tackifying resin
+ plasticizer
PSA
Window
1.E+05
- 10
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10
+ 10
Tg (°C)
Formulating SBC based PSA
High SP C9 resin : effect on performances
Material
Quantity
SIS
Tack = affe cte d by Norsolène S 155 %
30
44.5
25
50 to 25
NORSOLENE S 155
20
N / 25 mm
WINGTACK C5
0 to 25
Plasticizer
15
10
5
5
0
Antioxidant
0
0.5
10
20
30
40
50
60
% Norsolène S 155
(WINGTACK + NORSOLENE S 155 = 100)
Re sistance at 70 °C=de pe nding on Norsolène S 155
%
40
180
35
160
30
140
Time ( hours)
N / 25 mm
Peel strength = depending on Norsolène S 155 %
25
20
15
120
100
80
60
10
40
5
20
0
0
0
10
20
30
40
50
0
60
L105-1 _ January 2010
10
20
30
% Norsolène S 155
% Norsolène S 155
11
40
50
60
Formulating SBC based PSA
MATERIAL
EFFECTS
TYPE
SBC
Thermoplastic behaviour
provides flow and bond
SBS, SIS, SEBS
Cohesion/strength
Tackifying resin ( compatible
with Midblock)
Reinforcing resin (compatible
with endblock)
Increase Tg of Midblock
Wingtack C5 and C5/C9
Decrease viscosity
Wingtack 10 (liquid C5
polymer: no bleeding)
Increase cohesion and
Norsolene S155
T° resistance
Fillers
Reduce cost
Calcium carbonate
Pigment
Plasticizer
Reduce viscosity, cohesion,
modulus and hardness
Increase tack at low
temperature
Antioxidant
L105-1 _ January 2010
Reduce degradation of PSA
during manufacturing and
use
12
Oil (naphthenic, paraffinic)
Formulating SBC PSA
Styrene content:
Increases the cohesion
Decreases tack at room temperature
PS block MW:
Increases tensile strength
Increases temperature resistance
Increases Hot-melt viscosity
Diblock content:
Increases tack and adhesion
Decreases hardness
Decreases cohesion
Increases label convertibility
SBS is more cohesive and less tacky than SIS.
SBS need to be tackified with C9/C5 resins which will plasticize as well
the PS end blocks with the following consequences :
Increase of tack/adhesion
Possible decrease of cohesion
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Formulating SBC PSA
Effect on performances with the increase of different parameters:
Parameters
Polymer
Tack
Adhesion Cohesion
Quantity
Styrene
Mw (PS)
Diblock
Tackifying resin
Quantity
% aromatic
Mw
Tg
Reinforcing resin
Quantity
(few)
Mw
Tg
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(few)
SAFT
Coating process
Drying /
Cooling
Roll of
finished
material
Liner
Laminating
Release or anchorage
treatment (silicone /
Corona, Flame)
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PSA coating
15
Facestock
(for labels)
or protection
(for tapes)
Coating process
Raw
materials
Formulation
Coating
Coating on different substrates
Printing
Cutting
a
Cr
Polyolefin (PE, PP…)
Silicone (for paper and PVC substrates)
PET
y
lle
a
yV
Release liner
Different coating systems
Mayer bar
Gravure roller
Knife
Slot die
Curtain coating
…
Adhesive
Facestock
Lab coating machine
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Testing
DMTA: Dynamical Mechanical Thermal Analysis
Shear
Loop tack
Probe tack
10
MW and
polydispersity
y
10
2.5
Tack
= adhesion
10 9
G" (Pa)
Peel
Entranglement
s = Cohesion
10 8
2.0
Flow
10 7
1.5
tan_delta
G' (Pa)
10 6
1.0
10 5
10
4
0.5
Green: G’’= viscous modulus
10 3
Red: Tan δ =G’’/G’
2
10
-60.0
-42.0
-24.0
-6.0
12.0
30.0
48.0
66.0
Temp [°C]
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Blue: G’ = elastic modulus
17
84.0
102.0
0.0
120.0
Testing
Adhesion: strength of the interface between the
adhesive and the substrate, measured by peel test with
an angle of 90° or 180°.
Adhesive
failure
Substrates
180° peel
Tack: initial adhesion, measured by loop tack or rolling ball tack
Rolling ball tack
Loop tack
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Testing
Cohesion: intrinsic strength of the adhesive, measured by shear test
Adhesive
Substrates
Cohesive failure
Static shear
SAFT: Shear Adhesion Failure Temperature
(cohesion measured under an increase of temperature)
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Optimisation
Design of experiments are often used to optimise formulations in order
to reach the best compromise, depending on the final application.
A: Wingtack ET
2
60.0
113
2
0.0
0.0
116
110
120
123
2
2
15.0
B: Norsolene
S155
L105-1 _ January 2010
45.0
15.0
C: Oil
SAFT°C
20
Wingtack range
C9 modified C5
Pure C5
5
0
WT 10 (10°C)
WT Plus (96°C)
8
15
WT Extra (97°C)
WT ET (95°C)
25
WT STS (94°C)
30
Aromatic
content %
WT 86 (87°C)
WT 95 (98°C)
WT RWT 7850 (102°C)
WT 98 (98°C)
Isoprene compatible
Butadiene compatible
Pure C5 (pure aliphatic hydrocarbon) resins are compatible with isoprene
C9 modified C5 (aromatic modified C5) resins are compatible with isoprene,
butadiene and styrene (plastification of styrene end-blocks)
⇒ the best compatibility gives the best tack and adhesion
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Wingtack range
Typical
values
WT 10
WT 95
WT RWT
7850
WT 98
WT
PLUS
WT
EXTRA
WT
ET
WT
STS
WT
86
R&B SP, °C
10
98
102
98
96
97
95
94
87
Tg , °C
-31
55
52
48
53
52
50
44
42
1.5
1.7
2.4
3.1
1.6
1.4
2.0
3.0
1.2
Mn
370
1100
1000
1000
1000
1100
1000
850
650
Mw
500
1700
2100
2000
1600
2000
1600
1500
1300
Mw/Mn
1.4
1.5
2.1
2.0
1.6
1.8
1.6
1.8
2.0
COLOUR, G
(50% Toluene
solution)
GPC g/mol
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Application vs adhesive performances
Classification of PSA
Permanent (paper labels, packaging tapes, brown envelopes…)
High initial tack
High adhesion
Cohesion depending on application
Repositionable (book covers, white envelopes…)
High final adhesion but low build-up in performance (can be removed and replaced
immediately after sticking, not possible after a couple of days)
Medium to low tack
Cohesion depending on application
Removable (temporary protections, masking tapes…)
Must not damage the substrate or leave any residue when removed
High cohesion
Medium tack
Adhesion depending on application
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Application vs market: Labels
a
Cr
Label construction
y
lle
a
yV
Release liner
Adhesive
Examples
Face stock
Face stock
treatment
Protective liner
Paper
None
Silicone
Plastic (PE, PP)
Corona, Flame
Non treated plastic
PVC
None
Silicone
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Facestock
Application vs market: Labels
Formulations
SBC with high di-block content is compulsory to have good die-cutting (low elastic
modulus and high Tan δ at low frequency)
High tackifying content
High oil content, naphthenic oils are preferred because they will bring higher tack
Key performance characteristics
Good die-cutting and convertibility (low elastic modulus)
High tack on low energy substrates (achieved with a high level of tackifier)
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Application vs market: Labels
Orientation formulations
Permanent label
Material
Low temperature label
Quantity
Material
Quantity
SIS (16%S, 55% DB)
15
SIS (16%S, 55% DB)
15
SBS (33%S, 78% DB)
20
SBS (33%S, 78% DB)
20
Wingtack ET
30
Wingtack ET
45
Wingtack 86
25
Wingtack 10
10 - 20
Naphthenic oil
10
Naphthenic oil
0 - 10
Antioxidant
1
Antioxidant
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1
Application vs market: Tapes
Single coated
Tape construction
Easy release coating (LAB)
Backing
Primer
Examples
Backing
Adhesive
Anchorage
treatment
Release
Non polar plastic
(PE, PP)
Corona, Flame
None
Polar plastic (PET)
Corona, Flame
LAB*
Paper
Primer
Silicone
Reinforced tape
Release coating
Backing
Bundles of reinforcing filaments
Adhesive
Double coated
Textile
None
LAB
PVC
Primer
None
Release liner
Adhesive
Carrier
Adhesive
*LAB= Easy release coating
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Application vs market: Tapes
Formulation
Highly cohesive polymer (high styrene, low di-block content…)
Medium quantity of tackifying resin
Just the oil quantity needed for processing (to decrease migration)
Wingtack 95 can be used to have low noisy tapes (in SIS based formulations)
Norsolene S155 can be added up to 10% to reinforce cohesion and temperature
resistance
Key performance characteristics
High cohesion is generally required
Good wetting
Other properties depend on final application
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Application vs market: Tapes
Orientation formulations
OPP tape
Kraft tape
Material
Material
Quantity
Quantity
SIS (15%S, 19% DB)
40
SIS (15%S, 38% DB)
Wingtack 98
48
Wingtack 98
45 - 50
Naphthenic oil
11
Oil
5 - 10
Antioxidant
1
Antioxidant
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45
1
Application vs market: Tapes
Orientation formulation for OPP tapes using SIBS polymer
Material
PSA Tape PSA Tape
Kraton D1171™ (SIBS 18%S, 26%DB)
20
20
Kraton D1118™ (SBS 33%S, 78%DB)
20
-
-
20
49.8
49.8
Nyflex 222™
10
10
Antioxidant
0.2
0.2
Rolling ball tack (cm)
1.4
1.7
Loop tack (N/25mm, ss)
36.7
27.3
180° Peel (N/25mm, ss)
24
15.1
SAFT (°C, 1/2kg)
84
83
Kraton D1102™ (SBS 29.5%S, 17%DB)
Wingtack STS
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Application vs market: Tapes
Orientation formulations
Masking tape
Material
Quantity
SIS (15%S, 19% DB)
35
Wingtack Plus
44
Norsolene S155
9
Calcium carbonate
5
Titanium dioxide
1
Naphthenic oil
5
Antioxidant
1
L105-1 _ January 2010
Key performance characteristics :
Very good cohesion
No transfer after ageing
31
Application vs market: Films
Film construction
Examples
Face stock
Face stock
treatment
Protective liner
PE, PP
Corona, Flame
None
PVC
None
Silicone
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Application vs market: Films
Orientation formulations
SB protective film
HM protective film
Material
Material
Quantity
Quantity
SIS (15%S, 19% DB)
45
Natural rubber
50
Wingtack 98
50
Wingtack 95
45
Paraffinic oil
5
Paraffinic oil
5
Antioxidant
1
Antioxidant
1
Solvent
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To get the right
viscosity
WINGTACK in PRESSURE SENSITIVE ADHESIVE
These results obtained in our laboratory are given in good faith according to the method used and the samples checked. The values cannot be used to set specifications.
They are indicated without Cray Valley’s guarantee or liability. All given formulations are starting formulations and they are indicated without Cray Valley’s guarantee or
liability. They are based on our present technical knowledge and experience. They do not relieve processors of the responsibility of carrying out their own tests and
experiments, because many factors that could influence the result may arise during processing and application; neither do they imply or give legally binding assurance of
certain properties or of suitability for a specific purpose. Any proprietary formulation should be respected.
Shelf life : Norsolene and Wingtack resins are inert and stable. Their shelf life mainly depends on the storage conditions and end use. Their average shelf life is about 2
years. This average shelf life is given without Cray Valley’s guarantee because Cray Valley does not control end uses and the storage conditions at customers.
Storage : all resins with a low softening point present a risk of solidifying, which increases in hot weather. Therefore for softening points of less or equal to 100 °C, we
recommend : storage in a cool (25 °C max), ventilat ed area, out of the sunlight; do not stack pallets; avoid storage for prolonged period.
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