The Zincotek process allow to transform some steel
making dusts in activating additives in the rubber vulcanization process. The process needs specific plants and additives for
the waste refining: after this treatment the dusts have a similar property
to activate the vulcanization process as the zinc oxide called "green
seal" has (traditionally used in the rubber sector). The composition and the properties of different
mixtures of natural rubber, produced during the preliminary experimentation
using some typologies of this activating agent instead of the Zinc "green
label" are hereafter reported. The composition of the mixtures are the following:
|
Abbreviation mixtures of natural rubber
|
|
|
Green label
|
Zincotek Z100
|
Zincotek Z50
|
Zincotek F10
|
Zincotek F25
|
|
Ingredients
|
|
|
|
|
|
|
Natural rubber
|
100
|
100
|
100
|
100
|
100
|
|
Oxide green label
|
5
|
-
|
-
|
-
|
-
|
|
Oxide Z100
|
-
|
5
|
-
|
-
|
-
|
|
Oxide Z50
|
-
|
-
|
5
|
-
|
-
|
|
Oxide F10
|
-
|
-
|
-
|
5
|
-
|
|
Oxide F25
|
-
|
-
|
-
|
-
|
5
|
|
Stearic acid
|
2
|
2
|
2
|
2
|
2
|
|
Black HAF N 330
|
35
|
35
|
35
|
35
|
35
|
|
TBBS
|
0,7
|
0,7
|
0,7
|
0,7
|
0,7
|
|
Sulphur
|
2,25
|
2,25
|
2,25
|
2,25
|
2,25
|
|
Total
|
144,95
|
144,95
|
144,95
|
144,95
|
144,95
|
The mixtures based on natural rubber have been
vulcanized at 160°C following the UNI norm 8342; during the vulcanization of each
mixture the reologic characteristics of each mixture have been registered, with
the hardened mixtures some samples of 6 mm for the hardness test have been
arranged (following the UNI norm 4916) and some samples for
the resistance to tensile stress (type 1 UNI 6065). The obtained results are the following:
|
Mixtures
|
|
|
|
Green label
|
Zincotek Z100
|
Zincotek Z50
|
Zincotek F10
|
Zincotek F25
|
|
Minimum torque
|
lb.in
|
5,3
|
3,8
|
6,0
|
6,8
|
4,9
|
|
Maximum torque
|
lb.in
|
32,9
|
31,8
|
25,7
|
24,4
|
18,6
|
|
Scotching time
|
min
|
2,9
|
2,6
|
2,8
|
2,6
|
2,9
|
|
Vulcanization optimum
|
min
|
7,0
|
6,9
|
4,8
|
4,4
|
4,3
|
|
Hardness
|
Shore A3
|
54,0
|
54,5
|
44,5
|
41,5
|
37,5
|
|
Tensile strength at 300%
|
MPa
|
10,7
|
9,43
|
6,36
|
4,93
|
3,42
|
|
Breaking resistance
|
Mpa
|
27,5
|
29,1
|
18,32
|
5,95
|
12,6
|
|
Elongation at breaking point
|
%
|
540
|
570
|
550
|
570
|
590
|
Part of the specimens have been subjected firstly at
thermal ageing test (3 days at 70°C following the UNI-ISO 88 norm) and
then to a control of the physical mechanical characteristics; the obtained
results have been collected in the following table where also the variation
found after the comparison with the not aged specimens are included:
|
Mixtures
|
|
|
|
Green label
|
Zincotek Z100
|
Zincotek Z50
|
Zincotek F10
|
Zincotek F25
|
|
Hardness
|
Shore A3
|
55,0
|
51,0
|
40,0
|
36,0
|
32,0
|
|
Variation from untreated mixtures
|
%
|
+1
|
-3,5
|
-4,5
|
-5,5
|
-5,5
|
|
Tensile strength at 300%
|
MPa
|
12,4
|
12,4
|
3,8
|
2,62
|
2,35
|
|
Variation from untreated mixtures
|
%
|
+16
|
+31
|
-40
|
-47
|
-31
|
|
Breaking resistance
|
Mpa
|
23,4
|
23,2
|
4,53
|
3,78
|
3,84
|
|
Variation from untreated mixtures
|
%
|
-15
|
-20
|
-75
|
-75
|
-69
|
|
Elongation at breaking point
|
%
|
475
|
475
|
335
|
385
|
430
|
|
Variation from untreated mixtures
|
%
|
-12
|
-17
|
-39
|
-32
|
-27
|
The composition and the properties of different rubber
mixtures SBR produced during the preliminary experimentation using some
typologies of this activating agent instead of zinc oxide "green
label" are hereafter reported. The composition of the produced mixtures are the
following:
|
Mixtures of rubber SBR
|
|
|
Grenn label
|
Zincotek Z100
|
Zincotek Z50
|
Zincotek F10
|
Zincotek F25
|
|
Ingredients
|
|
|
|
|
|
|
SBR 1500
|
100
|
100
|
100
|
100
|
100
|
|
Oxides green label
|
3
|
-
|
-
|
-
|
-
|
|
Oxide Z100
|
-
|
3
|
-
|
-
|
-
|
|
OxideZ50
|
-
|
-
|
3
|
-
|
-
|
|
Oxide F10
|
-
|
-
|
-
|
3
|
-
|
|
OxideF25
|
-
|
-
|
-
|
-
|
3
|
|
Stearic acid
|
1
|
1
|
1
|
1
|
1
|
|
Black HAF N 330
|
50
|
50
|
50
|
50
|
50
|
|
TBBS
|
1
|
1
|
1
|
1
|
1
|
|
Sulphur
|
1,75
|
1,75
|
1,75
|
1,75
|
1,75
|
|
Total
|
156,75
|
156,75
|
156,75
|
156,75
|
156,75
|
The mixtures based on rubber SBR have been
submitted to vulcanization tests at 160°C following the UNI 8342 norm; during the vulcanization of each mixture the
reologic characteristics of each mixture have been registered, with the
hardened mixtures some samples of 6 mm for the hardness test have been
arranged (following the UNI norm 4916) and also some samples
for the resistance to tensile stress (type 1 UNI 6065). The obtained results are collected in the following
table:
|
Mixtures
|
|
|
|
Green label
|
Zincotek Z100
|
Zincotek Z50
|
Zincotek F10
|
Zincotek F25
|
|
Minimum torque
|
lb.in
|
10,5
|
10,1
|
10,3
|
19,6
|
10,1
|
|
Maximum torque
|
lb.in
|
42,6
|
41,9
|
36,1
|
35,8
|
34,1
|
|
Scotching time
|
min
|
3,9
|
3,8
|
3,3
|
3,8
|
3,9
|
|
Vulcanization optimum
|
min
|
13,6
|
13,1
|
11,9
|
12,6
|
13,5
|
|
Hardness
|
Shore A3
|
65,5
|
66,0
|
63,0
|
63,0
|
62,5
|
|
Tensile strength at 300%
|
MPa
|
19,1
|
17,0
|
15,1
|
12,5
|
10,5
|
|
Breaking resistance
|
Mpa
|
26,4
|
26,8
|
22,2
|
22,8
|
23,7
|
|
Elongation at breaking point
|
%
|
430
|
440
|
465
|
490
|
520
|
Part of the specimens have been subjected firstly at
thermal ageing test (3 days at 70°C following the UNI-ISO 88 norm) and
then to a control of the physical mechanical characteristics; the obtained
results have been collected in the following table where also the variation
found after the comparison with the not aged specimens are included:
|
Mixtures
|
|
|
|
Green label
|
Zincotek Z100
|
Zincotek Z50
|
Zincotek F10
|
Zincotek F25
|
|
Hardness
|
Shore A3
|
69,5
|
69,0
|
68,0
|
68,0
|
66,0
|
|
Variation from untreated mixtures
|
%
|
+4
|
+3
|
+5
|
+5
|
+3,5
|
|
Tensile strength at 300%
|
MPa
|
23,2
|
21,6
|
17,8
|
16,4
|
14,1
|
|
Variation from untreated mixtures
|
%
|
+21
|
+27
|
+18
|
+24
|
+34
|
|
Breaking resistance
|
Mpa
|
27,2
|
28,1
|
25,8
|
23,8
|
25,1
|
|
Variation from untreated mixtures
|
%
|
+3
|
+5
|
+16
|
+4
|
+6
|
|
Elongation at breaking point
|
%
|
345
|
365
|
410
|
400
|
460
|
|
Variation from untreated mixtures
|
%
|
-20
|
-17
|
-13
|
-22
|
-13
|
In the process only a minimum
fraction of the wastes is thrown away and the energy consumption necessary for
the process development is surely inferior to the energy used on the
traditional products on the market.
|
