Ecorr® Reclaim in compounds

In the technical brochures for Ecorr® RBR and Ecorr® RNR
a detailed overview is given of different applications inwhich a rubber reclaim can be used. Each virgin compound responds different when a part of the virgin rubber
is replaced by rubber reclaim. Not only the physicalproperties but also the processing properties, such as
vulcanisation behaviour, are influenced. If a reclaim isused in a compound, it is possible and / or necessary to
optimise the total compound recipe. During the years,
Rubber Resources has developed different techniques tominimise these effects. In this brochure examples are
given of compounds in which the different parts of virginrubber are replaced by rubber reclaim.

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Index
Ecorr® RNR Reclaim Natural Rubber in truck tyre tread compound

page 2Ecorr® RNR Reclaim Natural Rubber in tyre tread compound

page 5Storage hardening of Ecorr® RNR Reclaim Natural Rubber

page 6

Multiple reclaiming with Ecorr® RNR Reclaim Natural Rubber

page 7®

Ecorr RBR70 Reclaim Butyl Rubber in inner liner compounds

page 8Ecorr® RNR Reclaim Natural Rubber in truck tyretread compound
Rubber Resources Ecorr® RNR can be added on top of anof this compound with adjustment of the curing system.

existing compound, with adjustment to the curing

The substitution of virgin rubber with a reclaim is done

system. Also it can be used as a partial substitute for thefor Ecorr® RNR B01. As can be seen from the examples,

natural and / or SBR rubber, with adjustment to rubber

it depends on the Ecorr® RNR type and the method ofhydrocarbon content. It is important to notice that theaddition to a compound. For concentrations up to 15 phr

rubber content of a rubber reclaim is about 50% andof reclaim, no difference in the properties of a truck tyre

therefore 1 part of virgin rubber has to be replaced by 2

tread compound due to the compounding methods isparts of rubber reclaim. In table 1 an example is given inobserved. For higher concentrations compounding on

which a truck tyre tread compound is used as a reference

top results in better properties, though the compoundcompound. Two types of Reclaim Natural Rubber,

price reduction is lower.

®

®

Ecorr RNR B01 and Ecorr RNR B11, are added on top

Reference compound

Ecorr® RNR B01 on top

Ecorr® RNR B01 partial

Ecorr® RNR B11 on topof reference compoundsubstitute of natural rubberof reference compound

NR

100

100

97.5 94.8 89.6 84.4 73.5

100

Carbon black

50

50

50

50

Low PCA Oil

5

5

5

5

Zinc oxide

5

5

5

5

Stearic Acid

2

2

2

2

IPPD

1

1

1

1

TMQ

2

2

2

2

Par. Wax

2.5

2.5

2.5

2.5

Reclaim B01

0

5

TBBS

1.5

1.54 1.58 1.66 1.73 1.89

1.50

1.54 1.58 1.67 1.75 1.91

Sulphur

1.5

1.54 1.58 1.66 1.73 1.89

1.50

1.54 1.58 1.67 1.75 1.91

10

20

30

50

Table 1 Recipes for substitution or addition of reclaim in an existing compound.

2

5

10

20

30

50

5

10

20

30

50

Influence on physical properties
Figure 1 Comparison of tensile strength between addition of Ecorr®
RNR B01 and B11 on top of an existing compound and substituting B01
reclaim for RHC (see table 1). Up to 10 phr, no difference between typesof reclaim and way of compounding can be seen. At higher concentrations, adding on top results in higher tensile strengths.

Figure 2 Comparison of elongation at break between addition of Ecorr®
RNR B01 and B11 on top of an existing compound and substituting B01
reclaim for RHC (see table 1). Here the same is true as for the tensile
Figure 1

strength: Up to 10 phr no difference can be seen, above that, adding
reclaim on top of the compound gives better results.

Figure 2
Figure 3

Figure 3 Comparison of modulus (300%) between addition of Ecorr® RNR
B01 and B11 on top of an existing compound and substituting B01 reclaim
for RHC (see table 1). Substitution for RHC gives more stable values.

Figure 4 Comparison of hardness between addition of Ecorr® RNR B01
and B11 on top of an existing compound and substituting B01 reclaim for

Figure 4

RHC (see table 1). When adding B01 or B11 on top of the reclaim it provides comparable values as for the reference compound.

Figure 5 Comparison of Abrasion between addition of Ecorr® RNR B01
and B11 on top of an existing compound and substituting B01 reclaim for
RHC (see table 1). Adding B11 on top of a compound results in the lowest
increase.
Figure 53

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Figure 6 Comparison of tear strength between addition of Ecorr® RNR
B01 and B11 on top of an existing compound and substituting B01 reclaim
for RHC (see table 1). Here, adding on top results in the best values.

Figure 6
Figure 7 Comparison of the compression set between addition of Ecorr®
RNR B01 and B11 on top of an existing compound and substituting B01
reclaim for RHC (see table 1). As expected adding on top results in thelowest values.

Figure 7
Figure 8 Comparison of rebound resilience between addition of Ecorr®
RNR B01 and B11 on top of an existing compound and substituting B01
reclaim for RHC (see table 1). On top adding of reclaim has almost no
influence on the rebound resilience.

Figure 8
Figure 9(After ageing: 14 days at 70 °C). Comparison of Tensile

Strength (MPa) between addition of Ecorr® RNR B01 and B11 on top of
an existing compound and substituting B01 reclaim for RHC (see table 1).
Addition of reclaim improves ageing behaviour because the tensile
strength drops less than the reference compound.

4

Figure 9

Ecorr® RNR Reclaim
Natural Rubber in tyretread compound

SBR 1500
BR 1220
B01
ISAF N234

Besides the substitution of SBR rubber by a reclaim, also
other changes to the compound recipe are possible and/Low PCA oil
Stearic acid
Struktol 40 MS

or necessary. For example, introduction of reclaim

TMQ

generaly leads to shorter vulcanisation times (decrease

IPPD

in ts2 and t90 ). In table 2, two possibilities are given
to compensate this behaviour. First 0,5 phr of a

Antilux 654
ZnO

VirginCompound+20 phr
B01

+PVI

-PVI
-15 phr CB-10 phr oil

80
20
75
25
1
3
2
2
1.5
5

70
20
20
75
25
1
3
2
2
1.5
5

70
20
20
75
25
1
3
2
2
1.5
5

70
20
20
60
15
1
3
2
2
1.5
5

1.5
2.4
-

1.5
2.5
0.5

1.5
2.4
-

Pre-Vulcanisation-Inhibitor (PVI) is added. It can be seen

TBBS

that this leads to an increase of ts2 and t90. On the other

SU-109hand, by using this PVI, also the price of the total

PVI

1.5
2.4
-

Mooney

71

75

73

71

11
68
4’39’’
7’22’’
10’20’’

1469
3’51’’
6’02’’
8’40’’

1369
5’26’’
8’57’’
11’25’’

1271
4’54’’
8’21’’
10’53’’

1.7
2.9
6.9
8.6
11.7

2.3
5.2
9.3
13.3

2.1
4.9
9.0
12.9

2.0
4.6
8.4
12.4

17.4
577

14.7
456

14.8
456

15.5
480

71
1.17
81

74
1.18
106

74
1.18
82

75
1.16
75

62
57

60
56

57
56

65
59

compound is increased. A more efficient way of increasing the vulcanisation time is by leaving out extra partsof carbon black and processing oil, for these materials
are also present in the reclaim.

ML(1+4)@100 °C
Rheo @ 160 °C
ML

The last column shows the advantages of this method:
1. More comparable vulcanisation behaviour to thevirgin reference compound.
2. An increase of several physical properties such as
tensile strength, abrasion, tear strength.
3. Lower compound price due to further savings on carbon black and processing oil.

MH
ts2
t50
t90
Modulus (MPa)
100%
200%
300%
400%
500%

It must be noted that these are just two examples ofcompound optimisation. The most efficient method
differs for each compound.

Tensile strength (MPa)Elongation at break (%)
Hardness (° Shore A)

Table 2In the first column the recipe and the properties of a tyre tread

Density (g/cm3)

compound are given. In the second, the influence of interchanging 10

Din Abrasion (mm3)parts of the SBR rubber by 20 parts of B01 reclaim (ñ 50% rubber) is

Tear Delft

noted. In the last two columns two possible optimisation steps are given
with the effect on the compound properties.

[N]// [N]

5

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Storage hardening of Ecorr® RNR Reclaim Natural Rubber
The phenomenon of the hardening of natural rubber
during storage is well known in the rubber industry. Dueto the high proportion of natural rubber in tread reclaim,
the hardening behaviour of reclaim during storage issimilar to that of natural rubber.

Figure 10

Increase in Mooney as a function of storage time andtemperature (M 0 = 40)

The Mooney viscosity of tread reclaim increases withprocesses.

Increases in viscosity are largely reversible with a small

The increase is dependent on storage time andamount of milling. As shown in figure 11, the viscosity oftemperature (see figure 10). It can be calculated with thethe aged reclaim decreases sharply during the first

following empirical equation:

minute of milling; further the decline in viscosity is ana-

time

due

to

physicalandchemicallogous to that of fresh reclaims. Afterwards, the aged
Mt

= Mooney after t days of storage

reclaim behaves like fresh reclaim, having a much lower

M0= Mooney at the day of production

Mooney viscosity. Reclaim with an increase in Mooneyt= storage time in days

viscosity of approximately 20 points can be masticateda= 0.04 for T = 23 °C

easily with a 5% increase in total mixing energy. The= 0.15 for T = 50 °C

processing behaviour and the product properties ofcompounds with aged vs. fresh reclaim (having thesame Mooney viscosity at the day of production) do not

M t = M 0 * (1 + a * t

0.55

)

0.00
1.00
2.00
3.00
4.00
5.00

Figure 11 Mooney as a function of time on a mill for fresh and aged
reclaims.

0.00

6

differ significantly.

1.00

2.00

3.00

4.00

5.00

Multiple reclaiming with Ecorr® RNR Reclaim
Natural Rubber
Multiple reclaiming occurs when scrap rubber containing reclaim is itself reclaimed. Reclaim as a partial substitute is
generally used in concentrations not higher than 20%. In this concentration range only slight differences in propertiesare caused by multiple reclaiming (see figure 8).
The tensile strength of a compound containing a percentage of reclaim can be described as follows:T= Tensile strength of the compound containing a %		reclaim
T = T 0 (1 - α ) + T 1 ( α - _ α n) + Σ T n α nn-2nT 0 = Tensile strength of the compound without reclaim
T n = Tensile strength of the reclaim after n reclaiming		stepsα= Percentage of reclaim in the compound

This equation is based on a linear relationship between the compound's reclaim content and the tensile strength of thereclaim as they relate to the resulting tensile strength of the compound. Figure 12 shows the effect of multiple reclaimingon the tensile strength of a compound containing reclaim, both calculated and measured values. The calculation of thetensile strength of this natural rubber compound containing 20% (= a) reclaim being reclaimed for the first time (n=1) will
yield a tensile strength of 21.1 MPa:
T = 24.4 MPa (1 - 0.2) + 7.9 MPa * 0.2 = 21.1 MPa
The tensile strength of the same compound containing recycled material which has undergone up to three reclaiming
steps is 21.0 MPa:
T = 24.4 MPa (1 - 0.2) + 7.9 MPa (0.2 - 0.22 - 0.23 ) + 6.6 MPa * 0.22 + 6.0 MPa * 0.23
= 21.0 MPa

Figure 12 The influence of multiple reclaiming on the properties of acompoundFigure 127

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Ecorr® RBR70 Reclaim Butyl Rubber ininner liner compounds
Introduction
Most of the Ecorr® butyl reclaim is utilised by the tyre

not yet complete. During consumer use of theindustry in BIIR- and CIIR-inner liner applications. Thistyre, layer separations might result from thesepart provides information on the influence of Ecorr®

RBR70 on the most important properties of BIIR- and
CIIR-inner liner compounds.

blisters.
4.

Economic considerations: compound price aswell as the possibility of reducing the inner
liner's thickness need to be considered.

The most important properties of an inner liner include:1.

Low air permeability: butyl- and halobutyl rub-The advantages of Ecorr® RBR70 Reclaim
Butyl Rubber in an inner liner compound:ber are characterised by very low gas permeability.

The use of Ecorr® RBR70 in bromobutyl- and chlorobutylinner liner compounds provides several technical and

Chlorine or bromine is introduced in the allyl position tocost benefits: The compound price can be reduced

the double bond in order to increase the reactivity of thethrough the incorporation of butyl reclaim. Increasing

butyl rubber and to make it co-vulcanisable with NR andthe load of butyl reclaim reduces air permeability.

SBR.
This allows for a reduction in thickness of the inner liner
2.

Good ageing- and fatigue-resistance: as aresulting in additional cost savings and in a reduction in

result of crack initiation and crack growth, airtyre weight. Flex fatigue resistance is improved. In

can penetrate between the plies of the tyrebromobutyl-compounds, ageing resistance and green

causing ply separations. In the case of truck

strength are improved. An increasing concentration oftyres, superior ageing performance is required

butyl reclaim improves air venting between bladder anddue to higher running temperature and theinner liner during vulcanisation.

need for good retreadability.

Compound recipes
3.

Good cured adhesion to NR: due to the low airpermeability of the inner liner compound, theThe following data were derived using two different

formation of trapped air is possible. This

compounds, one bromobutyl rubber based, and thetrapped air can cause blisters between theother chlorobutyl rubber based. The two compounds are

inner liner and the carcass ply, particularly at

typical in tyre inner liner applications. Mixing was

the end of the curing cycle when pressure in

performed in a 2.5 litre Homrich-laboratory mixer.

the bladder is reduced but vulcanisation is

8

Mixing step I (batch temperature: 135 oC)
BIIR X 2

100.0

l

l

l

l

l

---

5.0

15.0

20.0

25.0

30.0

Carbon black N 660

60.00

l

l

l

l

l

Koresin resin

4.00

l

l

l

l

l

Struktol 40 MS

7.00

l

l

l

l

l

Paraffinic oil

8.00

l

l

l

l

l

Stearic acid

2.00

l

l

l

l

l

Maglite D

0.15

0.15

0.16

0.17

0.17

0.17

MBTS

1.50

1.50

1.60

1.65

1.70

1.75

Zn0

3.00

3.10

3.20

3.30

3.40

3.50

Sulphur

0.50

0.50

0.55

0.55

0.55

0.60

table3 The bromobutyl inner liner compound

Ecorr® RBR70

Mixing step II (Batch temperature: 90 oC)

Compound data
Rheometer (0DR; 160 oC)
ts2
t90

3’50’’

3’20’’

3’10’’

3’05’’

3’00’’

2’55’’

17’05’’

17’20’’

17’10’’

17’10’’

17’20’’

17’55’’

CIIR 1066

70.0

l

SMR20

30.00

l

l

l

l

l

l

---

5.0

10.0

15.0

20.0

25.0

30.0

60.00

l

l

l

l

l

l

l

l

l

l

Mixing step I (batch temperature: 135 oC)

Ecorr® RBR70

table4 The chlorobutyl-inner liner compound

Carbon black N 660

l

l

l

l

l

Koresin resin

4.00

l

l

Struktol 40 MS

7.00

l

l

l

l

l

l

Paraffinic oil

8.00

l

l

l

l

l

l

Stearic acid

2.00

l

l

l

l

l

l

Zn0

3.00

3.08

3.17

3.25

3.33

3.41

3.50

MBTS

1.50

1.54

1.58

1.62

1.67

1.71

1.75

Sulphur

0.50

0.51

0.53

0.54

0.56

0.57

0.58

Mixing step II (Batch temperature: 90 C)oCompound data
Rheometer (0DR; 160 oC)
ts2

3’10’’

3’20’’

4’25’’

4’05’’

4’25’’

4’25’’

4’10’’

t90

9’30’’

17’20’’

11’20’’

11’10’’

11’30’’

11’50’’

11’30’’

Bromobutyl rubber has a high cure rate and short scorch time. For a better process safety the BIIR-compound contains
MgO and MBTS. Both chemicals are added during the first mixing step. The ZnO and sulphur should be added during thesecond mixing step.

9

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Influence of Ecorr® RBR70 on the properties of the BIIRand CIIR-compounds
Lower air permeability:
The addition of Ecorr® RBR70 results in a reduction in air
permeability. This is one of the most important advantages
for inner liner applications.

Figure 15 Influence of Ecorr®RBR70 on the elongation at break of a
BIIR- and a CIIR- inner liner compound (ASTM D 412).

Improved flex life after ageing:
Just the same as static properties, also dynamic properties can be improved by compounding with Ecorr®
Figure 13 Influence of Ecorr® RBR70 on the permeability of a BIIR- anda CIIR- inner liner compound (65 oC).

RBR70 (after ageing at 120 °C, 168 hours). The charts

Improved ageing resistance of the
BIIR-compound:

BIIR- and CIIR compounds.

below illustrate the effect on the flex fatigue behaviour ofAgeing resistance is improved by the addition of increasing amounts of Ecorr® RBR70, especially in the case of
the BIIR compound. Figure 14 and 15 illustrate the effecton tensile strength and elongation at break after ageing at
125 oC for 72 hours in hot air.

Figure 16 Influence of Ecorr®RBR70 on the flex fatigue resistance of a
BIIR- inner liner compound (De Mattia, ISO 132).

Figure 14 Influence of Ecorr®RBR70 on the tensile strenght of a BIIRand a CIIR- inner liner compound after ageing (ASTM D 412).

Figure 17 Influence of Ecorr®RBR70 on the flex fatigue resistance of a
CIIR- inner liner compound (De Mattia, ISO 132).>>10

Improved cured adhesion to NR:®

Cost savings:

The addition of Ecorr RBR70 results in stronger adhesion

Cost savings are achieved through lower compoundof halobutyl compounds to NR compounds in the cured

costs, and due to the reduction of the inner liner's

state. This effect is more applied in the case of bromobutyl

thickness. The latter can be achieved by adjusting thecompounds, whose cured adhesion is stronger inpermeability/ thickness ratio. The precise cost saving

comparison to the CIIR compounds.

depends on the current price for material costs andcompounding.

Other mechanical properties:
For the influence of Ecorr® RBR70 on the tensile strengthand elongation at break see figures 20 and 21; for theeffect on modulus and hardness see figures 22 and 23.

Figure 18 Influence of Ecorr®RBR70 on the adhesion of a BIIR- and a
CIIR- inner liner compound.

Improved green strength of BIIR-compounds:
The green strength of BIIR compounds is significantly
increased by the addition of up to 20 phr Ecorr® RBR70.
With loadings higher than 20 phr green strength remains

Figure 20 Influence of Ecorr®RBR70 on the tensile strenght of a BIIR- anda CIIR- inner liner compound (ASTM D 412).

on this high level. Figure 19 also illustrates the influenceon the green strength of a CIIR compound.

Figure 21 Influence of Ecorr®RBR70 on the elongation at break of a
BIIR- and a CIIR- inner liner compound (ASTM D 412).

<< Figure 19 Influence of Ecorr®RBR70 on the green strenght of a
BIIR- and a CIIR- inner liner compound.

11

Storage and handling of Butyl reclaim
1.

During storage the temperature should be cool(< 23°C, preferably < 15°C), dry (relative
humidity lower than 65%), dust free andmoderately ventilated.

2.

Reclaim should be protected from light, inparticular from direct sunlight and strong 		
artificial light with a high ultraviolet content.

Figure 22 Influence of Ecorr® RBR70 on the modulus of a BIIR and

3.

CIIR- inner liner compound (ASTM D 412).

Reclaim should be protected from circulating
air by a protective packaging or by storage inairtight containers. Ozone concentration in thestorage room should be below 10 ppm. 		
Therefore the storage area should not containany equipment capable of generating ozone.

4.

Reclaim should be stored under conditions freefrom compression, tension or other possible
sources of deformation.

5.

Although the mooney increase for butyl 		reclaim is very low, the reclaim inventory 		

Figure 23 Influence of Ecorr® RBR70 on the hardness of a BIIR and
CIIR- inner liner compound (o Shore A,ASTM D 2240).

should be rotated on a 'first in, first out' basis.

Influence on processability
No significant negative influence on theprocessability of the compound has been
observed.
The following influences should be mentioned:
1.

Tack is not significantly influenced.

2.

Die-swell is reduced, but mill shrinkage isincreased slightly.

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Phone: +31 (0)43 329 04 44 - Fax: +31 (0)43 329 03 03 - E-mail: info@rubber-resources.com - Website: www.rubber-resources.com
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without the prior written permission of Rubber Resources.
No responsibility is assumed by Rubber Resources for any injury and / or damage to persons or property as a matter of products liability,
negligence or otherwise, or from any use or operation of any methods, products, instructions or ideas contained in the material herein.