Performance resins in tread formulations –
Optimizing for wet, winter, and wear
Presentation given by:
Gennaro della Vecchia, Senior AD & TS Representative
Eastman
Presented at the Tire Technology Conference,
Hannover, Germany
March 5, 2019
Presentation prepared by:
Mark Arigo, Ph.D., Associate Scientist
Eastman
Expanding the “magic triangle” with Impera™ resins
Talk outline
 The “magic triangle” remains a challenging puzzle for tire
compounders to simultaneously optimize many tire properties.
Wet grip
 The challenge is finding ways to overcome the inherent
viscoelastic trade-offs associated with wet grip & rolling
resistance, wet grip & wear, and wet grip & snow grip
 In this presentation, we’ll explore how performance resins can
be vital tools used to expand magic triangle
1. Background: hydrocarbon resins
2. Balancing wet grip & rolling resistance with resins
Wear
Winter
(snow grip)
Standard performance triangle
Wet grip optimized with performance resins
Winter optimized with performance resins
Wear optimized with performance resins
3. Improving wear resistance with resins
4. Balancing wet grip & snow grip with resins
5. Conclusions
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chemical company
headquartered in
Kingsport, Tennessee
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employees
and more
than 50 manufacturing
sites around the globe
Serving customers in
approximately 100
countries
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Performance additives
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1,000,000
Molecular weight (g/mol)
Glass transition temperature °C
Hydrocarbon resins
Natural rubber
Polystyrene
PMMA
SBR
100,000
SIS - block
copolymer
PVC
10,000
1,000
Tg, ˚C
100
-100
0
100
200
 Resins are low MW polymers with a high Tg
• Mn range: ~ 500 to 1500 g/mol
• Tg range: ~ -20 to 100°C
 In tire performance applications, hydrocarbon resins are typically used because of polymer compatibility
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Aliphatic and aromatic balance in hydrocarbon resins
C9 and PMR hydrogenation
Aliphatic
Aromatic
Aromatic C9, PMR resin
Aliphatic C5 resins
Mixed C5 and C9
monomer sources
Each resin structure has a different effect on the viscoelastic properties of polymers.
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How resins improve compound performance
 Compatible resins act as viscoelastic modifiers for the polymer system and alter the dynamic properties of
the compound
 Compound wet grip improvement is derived mainly from “shifting” and/or “broadening” of the tanδ peak
(compound Tg)
• Tg shift depends on resin properties, and polymer-resin compatibility
Adding resin results in a
significant shift of Tg to higher
temperature
Fox equation (Tg for compatible
polymer blends):
Wet grip indicator
(tanδ at 0°C)
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1
𝑤𝑤1 𝑤𝑤2
=
+
𝑇𝑇𝑔𝑔 𝑇𝑇𝑔𝑔𝑔 𝑇𝑇𝑔𝑔𝑔
Balancing wet grip & rolling resistance with resins
With resin
Control
Improved resin
compatibility
WET
RR
RR
10 Hz, 0.1% dynamic strain, 0.4% static strain, 2°C/min, tension
At equal Tg, resins widen the tanδ peak and provide an increase in tanδ @ 0°C for better wet grip.
Resin compatibility plays an important role in balancing rolling resistance (tanδ @ 60°C).
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Improved wear resistance using Eastman Impera™
performance resins
 With resins, compounders can utilize low Tg polymer systems for improved treadwear while still achieving a
high Tg compound necessary for wet grip demands
Model
compounds:
High Tg
sSBR
with oil
Low Tg
sSBR
with oil
Low Tg
sSBR
with
resin A
Low Tg
sSBR
with
resin B
Polymer Tg (°C)
-30
-62
-62
-62
TDAE oil (phr)
47.5
45
—
—
Resin / type (phr)
—
—
45 / A
60 / B
Silica (phr)
80
90
90
100
Shore A
59
61
64
62
T at tanδ peak (°C)
-12
-43
-14
-12
Equivalent compound Tg
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Improved wear resistance using Impera resins
 A significant improvement in abrasion index is observed for model compounds with high loading of
resin – even better than low Tg polymer alone
• Wet grip properties close to high Tg polymer compound, but optimizations are still needed
Model compounds:
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High Tg sSBR
with oil
Low Tg sSBR
with oil
Low Tg sSBR
with resin A
Low Tg sSBR
with resin B
Polymer Tg (°C)
-30
-62
-62
-62
TDAE oil (phr)
47.5
45
—
—
Resin / type (phr)
—
—
45 / A
60 / B
Silica (phr)
80
90
90
100
Shore A
59
61
64
62
T at tanδ peak (°C)
-12
-43
-14
-12
T at E'' peak (°C)
-23
-51
-32
-30
WG: tanδ 5%, 0°C
0.96
0.31
0.79
0.86
RR: tanδ 5%, 60°C
0.19
0.16
0.18
0.19
Rebound RT
19.3
47.0
21.0
18.5
Rebound 70°C
55.5
60.2
55.3
52.4
Pico abrasion index
94
113
156
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Improved wear resistance using Impera resins
 LAT-100 abrasion tests also confirm the improvement in abrasion/wear resistance
Model compounds:
High Tg sSBR
with oil
Low Tg sSBR
with oil
Low Tg sSBR
with resin A
Wear – low severity
100
125
126
• Low Tg polymer improves low severity wear
Wear – high severity
100
108
116
• Resin further improves high severity wear
due to increased energy dissipation
Wear – average
100
120
125
Wet traction
100
82
103
Dry traction
100
98
106
Rolling resistance
100
133
109
Indexed values: higher = better
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• Low Tg polymer significantly reduces wet
traction
• Resin restores wet/dry traction to equal/better
than control despite lower hysteresis (tanδ)
values
Impact of resins on friction coefficient
 Four physical mechanisms are usually known to contribute to rubber friction:
μ = μh + μ a + μ c + μ v
• μh = hysteresis component due to the macroscopic dynamic deformation of the
elastomer induced by surface roughness
• μa = adhesion component arising from molecular interactions between the rubber and
the substrate
• μc = cohesion component due to the generation of cracks and wear in the rubber
material at the interface
• μv = viscous component due to the presence of a surface lubricant at the interface
 For wet/dry grip tread performance predictors, we only consider the hysteretic
contribution (tanδ)
The LAT-100 results suggest that resins may uniquely contribute to the
adhesion or cohesion component of the friction coefficient
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Wet grip / snow grip trade-off
 Balancing wet grip and snow grip is challenging
Increase Tg
because the DMA predictors are close in
temperature
 Methods to increase wet grip by only shifting
compound Tg and/or widening tanδ peak typically
sacrifice snow grip performance:
Better WG
• Better wet grip  high tanδ @ 0°C  want high Tg
• Better snow grip  low E* @ -20°C  want low Tg
 Snow grip (low E*) can be improved by increasing
the plasticizer phr, but there is a limit on lowering
the tread hardness without significantly impacting
other performance properties (handling, abrasion,
tear, etc.)
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Worse SG
Wet grip / snow grip trade-off in PCR tires
 Analysis of commercial tires shows a
 Typically, as wet grip is improved (higher
Winter
All-season
Better
clear trade-off between snow and wet
grip DMA performance predictors
tanδ @ 0°C), snow grip (E* @ -25°C) is
decreased
Improved
WET/SNOW
Source: Smithers’ reports 2013-2015, North American Market, passenger car tread analysis.
Better
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Summer
Wet grip / snow grip trade-off in PCR tires
 Snow and wet grip properties (lab predictors) are strongly correlated to the compound Tg
• Combination of tanδ peak temperature but also tanδ peak width
All-season
Winter
Summer
Better
Better
Winter
Source: Smithers’ reports 2013-2015, North American Market, passenger car tread analysis.
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All-season
Summer
 Change Tg via SBR/BR ratio:
Material
phr
SBR (20% styrene,
58% vinyl, Tg = -34°C)
60-40
BR (96% cis)
40-60
Silica
80
Silane
6.4
Oil (TDAE)
30
Better
Impact of Tg on wet grip/snow grip balance
Tg (°C) =
Changing Tg moves
performance along
trendline
 Well defined WET/SNOW trade-off that is
strongly dependent on compound Tg
10 Hz, 2% dynamic strain, 6% static strain, tension
Better
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Impact of resins on wet grip / snow grip balance
 Change Tg using resin and SBR/BR:
phr
SBR (20% styrene,
58% vinyl, Tg = -34°C)
60-40
BR (96% cis)
40-60
Silica
80
Silane
6.4
Oil (TDAE)
10
Impera resin (various
chemistries)
20
Better
Ingredient
 No resin (30 phr oil)
Tg (°C) =
 Impera resins (20 phr, various)
Changing Tg moves
performance along
trendline
Iso-WET: -7% SNOW
 Can compare iso-Tg, iso-WET, iso-SNOW
 Resins give provide a benefit in WET at equal
Iso-SNOW: +6% WET
Iso-Tg: +14% WET, +17% SNOW
SNOW due to tanδ peak broadening
 Resin compatibility affects the amount of Tg shift
10 Hz, 2% dynamic strain, 6% static strain, tension
& broadening
Better
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Impact of resins on wet grip / snow grip balance
 At equal Tg, resins broaden the tanδ peak to give improvement in WET, but consequently E’ increases
resulting in a decrease SNOW
― 50/50, no resin
― 40/60, 20 phr Impera™ resin A
― 40/60, 20 phr Impera™ resin B
WET
SNOW
Broaden
tanδ→
← E*
10 Hz, 2% dynamic strain, 6% static strain, tension
10 Hz, 0.1% dynamic strain, 0.4% static strain, 2°C/min, tension
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Strategy for improving wet & snow grip with Impera resins
 Compound objective: increase overall compound
hysteresis (improved wet grip) while balancing low
temperature compound modulus (maintain snow
grip)
inc.
Same Tg
Improved
WET
• Broaden Tg with combination of low Tg polymer and
high loading of high Tg resin
• Increase compound hysteresis and tanδ peak height
with high loadings of silica and resin
Broaden
• Balance compound hardness with increased loading
of total plasticizer (resin & oil)
Similar
SNOW
• Adjust compound Tg (tanδ peak) with polymer
system (SBR/BR), resin (high Tg), and oil (low Tg)
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A new approach to the “integral rubber” concept
 Nordsiek (1985) proposed the “integral rubber” concept for an ideal tire tread rubber compound
 By blending combinations of different elastomers, the viscoelastic properties of the tire compound can be tuned
for better general performance
• The result is broader tanδ curve to balance abrasion, ice grip, and wet grip performance
Reference:
Nordsiek, K. H. The "integral rubber" concept - an
approach to an ideal tire tread rubber. Kautschuk
und Gummi, Kunststoffe, 38/3,178-85 (1985)
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Strategy for improving wet & snow grip with Impera resins
Model compounds:
Formulation 1
Formulation 2
50
75
(20% sty, 58% vinyl, -34°C)
(15% sty, 30% vinyl, -62°C)
BR (phr)
50
25
Silica (phr)
80 (HD silica)
140 (low surface area)
Impera™ resin (phr)
20
36
Resin
TDAE oil (phr)
10
26
(high Tg)
Polymer
system
Total plasticizer (phr)
30
62
Shore A
66
65
M300 (MPa)
11.8
11.8
Tensile strength (MPa)
17.4
15.1
Elongation (%)
397
367
T @ tanδ peak (°C)
-35.0
-34.1
Oil
Filler
T @ E'' peak (°C)
-60.5
-51.7
(low Tg)
(silica)
Rebound @ RT
34.5
26.7
Rebound @ 70°C
51.9
51.6
Pico abrasion index to standard
123
133
SBR (phr)
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(low Tg)
Strategy for improving wet & snow grip with Impera resins
 Use of low Tg polymer and high resin loading (Formulation 2) greatly broadens the tanδ peak
 Combination of total plasticizer and high filler loading increases tanδ peak height
 Other compound changes (low surface area silica, oil/resin loading) help maintain low temperature modulus at similar level
Same Tg
― Formulation 1 (20 phr Impera resin)
inc.
← E'
― Formulation 2 (36 phr Impera resin)
tanδ→
Snow
Wet
Broad
tanδ→
← E*
10 Hz, 0.1% dynamic strain, 0.4% static strain, 2°C/min, tension
10 Hz, 2% dynamic strain, 6% static strain, tension
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Strategy for improving wet & snow grip with Impera resins
 Formulation 1 (vary SBR/BR, no resin)
in winter compounds due to broadening
of the tanδ peak
 Formulation 1 (vary SBR/BR & 20 phr
various Impera resins)
 To achieve larger improvements in wet
grip while maintaining snow grip, larger
formulation strategies must be used
Better
 Resin can be used to improve wet grip
 Formulation 2 (36 phr various
Impera resins)
• Resins play a significant role to broaden
Optimize along
trendline by
adjusting
compound Tg
+15-20%
WET
the tanδ, control the Tg, and optimize
the modulus/hardness
 Formulation can be further optimized
along the WET/SNOW trendline by
making shifting the compound Tg
through changes to the polymer system,
resin/oil ratio, etc.
10 Hz, 2% dynamic strain, 6% static strain, tension
Better
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A better resin for high loading applications
 Compounds with high resin loading have
― Impera resin A (low softening point)
been demonstrated to enable significant
performance gains and break traditional
trade-off
― Impera resin B (high softening point)
― New developmental resin
 However, high resin loadings can
accentuate polymer-resin incompatibility
 Eastman has a new developmental resins
for such applications with improved
compatibility at high loadings
 Improved compatibility and higher Tg
results in:
• Larger Tg shift
• Broader Tg peak
• Reduced RR trade-off
• Low impact on modulus
Improved compatibility
10 Hz, 0.1% dynamic strain, 0.4% static strain, 2°C/min, tension
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Conclusions
 Resins are an integral part to compounding
strategies to break the traditional compound
performance trade-offs:
Resin
• wet grip / rolling resistance
• wet grip / wear
• wet grip / snow grip
(high Tg)
Wet grip
Polymer
system
(low Tg)
 Resins modify the viscoelastic properties of the
compound to shift and/or broaden the tanδ
• Polymer-resin compatibility plays an important role in
obtaining the desired performance properties
 Resins enable compounders to achieve compound
performance through holistic formulation design
strategies
 Eastman technical experts work closely with
customers to optimize formulations – and balance
trade-offs – for superior performance
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Wear
Winter
Oil
Filler
(low Tg)
(silica)
Acknowledgements
 Contributors:
• Dr. Mark Ingratta, GL, Application Research
• Paul Madren, Market Development Manager
 Experimental contributions:
• Eastman Akron Rubber Lab, including:
 Jeff Wible, Lab Technician Associate
 Don Peloso, Lab Technician Associate
 Darrick Godbott, Rubber Lab Analyst
 Tom Matta, Rubber Lab Analyst
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