A RUBBER FORMULATION

Abstract

A method for manufacturing micronized rubber powders including grinding of a rubber granulated feedstock, size classification and storage of the micronized rubber powders thus obtained. A rubber formulation including at least one natural or synthetic rubber, a micronized rubber composition and optionally one or more of processing aids, antidegradants, fillers, accelerators and curatives. A method for manufacturing a rubber product, as well as to a solid rubber product.

Claims

1. A method for manufacturing micronized rubber powders comprising grinding of a rubber granulated feedstock, size classification and storage of the micronized rubber powders thus obtained, wherein during the grinding process an agent is used to prevent the rubber powder particles sticking to themselves, wherein the agent is chosen from the group of synthetic amorphous precipitated silica and silane-treated synthetic amorphous precipitated silica, or a combination thereof.

2. The method according to claim 1, wherein the total amount of the agent is a range of 0.1-4.0 wt. % based on the total weight of the micronized rubber powders.

3. The method according to claim 1, wherein the agent is in a fluffy state and the BET surface area of the agent is between 50 and 250 m.sup.2/g.

4. The method according to claim 1, wherein the agent is silane-treated synthetic amorphous precipitated silica.

5. The method according to claim 1, wherein the grinding process of the rubber granulated feedstock comprises a two-step grinding process, namely: a) ambient grinding, followed by b) cryogenic grinding, wherein especially step b) is carried out in a range of −40 to −80° C. for a rubber granulated feedstock comprising natural rubber and in a range of −20 to −60° C. for a rubber granulated feedstock comprising natural rubber and styrene-butadiene rubber.

6. The method according to claim 5, wherein the particle size of the rubber granulated feedstock before the grinding process is 2-5 mm.

7. The method according to claim 5, wherein the particle size of the rubber granulated feedstock after a) ambient grinding is 0.1-0.8 mm.

8. The method according to claim 1, wherein the rubber granulated feedstock is chosen from the group of natural rubber, synthetic polyisoprene rubber, high cis-1,4-polybutadiene rubber, medium vinyl polybutadiene rubber, high vinyl polybutadiene rubber, emulsion styrene-butadiene rubber, solution styrene-butadiene rubber, styrene-isoprene-butadiene rubber, styrene-isoprene rubber, butyl rubber, chlorobutyl rubber, bromobutyl rubber, polynorbornene rubber, ethylene-propylene rubber (EPR), ethylenc-propylene-diene rubber (EPDM), nitrile rubber, carboxylated nitrile rubber, polychloroprene rubber (neoprene rubber), polysulfide rubbers, polyacrylic rubbers, silicone rubbers, chlorosulfonated polyethylene rubbers, and various mixtures thereof.

9. The method according to claim 1, wherein said size classification provides at least two micronized rubber powders product streams, comprising an 80 mesh stream and a 40 mesh stream.

10. The method according to claim 9, wherein at least one of the 80 mesh micronized rubber powders product stream and the 40 mesh micronized rubber powders product stream is contacted with an agent chosen from the group of synthetic amorphous precipitated silica, silane-treated synthetic amorphous precipitated silica, organosilane and organic peroxide, or a combination thereof for obtaining an activated micronized rubber powder product, preferably an organosilane polysulphide type or disulfide type.

11. A rubber formulation comprising at least one natural or synthetic rubber, a micronized rubber powder obtained according to claim 1 and optionally one or more of processing aids, antidegradants, fillers, accelerators and curatives, wherein said rubber formulation comprises at least one activation component chosen from the group silane, NR latex, organic peroxides, polyoctenamer, curatives, polyethylene wax, emulsion styrene butadiene rubber (eSBR), liquid acrylonitrile butadiene rubber (NBR), zinc oxide and colloidal sulphur.

12. The rubber formulation according to claim 11, wherein the amount of the activation component(s) is in a range of 2-20 wt. %, based on the total weight of the rubber formulation.

13. The rubber formulation according to claim 11, wherein the activation component is silane.

14. The rubber formulation according to claim 13, wherein the amount of silane is in a range of 1-10 wt. %, based on the total weight of the rubber formulation.

15. The rubber formulation according to claim 11, wherein the activation component is a combination of silane and NR latex.

16. The rubber formulation according to claim 15, wherein the amount of silane is in a range of 5-9 wt. and the amount of NR latex is in a range of 4-8 wt. %, based on the total weight of the rubber formulation.

17. A method for manufacturing a rubber product on basis of a natural or synthetic master batch, comprising: i) a step of providing an activated micronized rubber powder product stream according to claim 10, ii) a step of providing of a natural or synthetic master batch, and iii) a step of mixing of the product of i) and the master batch of ii) for producing the rubber product.

18. The method according to claim 17, wherein said step of mixing is a co-extrusion step.

19. The method according to claim 17, wherein said step of mixing is carried out in the presence of one or more additional components, chosen from the group of natural rubber, synthetic rubber, peptizer, carbon black, recovered carbon black, silica, stearic acid, scorch retarder, antidegradants and plasticizer.

20. A solid rubber product obtained according to the method according to claim 17.

Description

EXAMPLES

[0051] Several test examples (see Table 1 and 2) were prepared out to investigate the performance of the rubber composition.

[0052] The test examples were compared with a so-called test recipe. The composition of the test recipe (according to ASTM D3191, ASTM D3191 excludes MRP) is shown in Table 1.

TABLE-US-00001 TABLE 1 Composition of test recipe PPHR MATERIAL WEIGHT UNIT % 100 SBR 1500 29.82 grams 54.22 3 Zinc oxide 0.89 grams 1.63 1 Stearic acid 0.30 grams 0.54 50 N550 carbon black 14.91 grams 27.11 27.67 MRP sample 8.25 grams 15.00 1.75 Sulphur 0.52 grams 0.95 1 TBBS 0.30 grams 0.54 184.4 Total: 55.00 grams 100 Batch weight: 55

[0053] The reference MRP sample is Cryofine 80 (Kargro) mesh, i.e. a cryogenically ground Micronized Rubber Powder produced exclusively from pre-selected end of life whole truck tyres, compliant with ASTM D5603 Class 80 1*.

[0054] Samples #1-#43 were prepared by mixing the components mentioned in Table 1 together with specific components. The rubber composition thus obtained was tested for several parameters, such as Mooney viscosity, Rheology Scorch time, ts2, Rheology T90, Rheology Delta S, Tangent Delta, Tensile Strength, Payne Effect,

[0055] M100M300, Ultimate Elongation, Tear Strength, and Abrasion Loss. The results of these tests are shown in Table 2. On basis of these performance parameters an average improvement rate was calculated (%). An average improvement rate >40% is identified as acceptable.

[0056] In Table 2 component Silane Si69 is Bis(triethoxysilylpropyl)tetrasulfide, Vestenamer 8012 is a trans-polyoctenamer, Alpha wax is polyethylene wax, Trigonox 29 and Luperox 231 are 1,1-Di(tert-butylperoxy)-3,3,5-trimethylcyclohexane.

[0057] From Table 2 one will see that sample #7 (6% Silane (Si69)) has an average improvement rate of 65.7%. For sample #43 an even higher average improvement rate is obtained, i.e. a value of 79.1%. A comparison between sample #7 and sample #42 shows that the combination of both silane and NR latex has resulted in a high average improvement rate.

TABLE-US-00002 TABLE 2 Rheology MRP Mooney Scorch Rheology Rheology Tangent Sample Description Content Viscosity time, ts2 T90 Delta S Delta Ref Reference compound ASTM D3191 0 85% 120% 120% 117% 90% (target values) Ref Reference compound ASTM D3191 15% 100%  100% 100% 100% 100%  (normalised values) untreated MRP 1 0.13% Chemlok 8212 + 4.6% water 15% 99% 101% 102% 104% 100%  as carrier 2 0.12% Chemlok 8212 bonding agent 15% 99% 102% 103% 104% 98% 3 0.36% Chemlok 8212 bonding agent 15% 97% 102% 103% 105% 99% 4 0.6% Chemlok 8212 bonding agent 15% 96% 101% 103% 106% 97% 5 2% Silane (Si69) 15% 96% 100% 104% 107% 96% 6 4% Silane (Si69) 15% 95%  98% 100% 110% 97% 7 6% Silane (Si69) 15% 85% 112% 115% 112% 94% 8 2.4% NR latex (dry) 15% 94% 103% 106% 100% 99% 9 2.4% NR latex plus low amount of 15% 94% 101% 103% 107% 97% curative blend 10 7.9% NR latex (dry) 15% 88% 106% 106%  98% 99% 11 8.2% NR latex (dry) plus high 15% 90%  99% 104% 115% 89% amount of curative blend 12 8% NR latex (dry) plus 1% organic 15% 88% 108% 112% 116% 92% peroxide curative 13 0.6% Megum W9500 bonding agent 15% 95% 101% 102% 108% 97% 14 1% SBR latex R4224 (dry) 15% 96% 105% 108% 103% 98% 15 3.1% SBR latex R4220 (dry) plus 15% 94% 101% 103% 107% 97% curative blend 16 3% Vestenamer granules plus high 15% 89% 104% 103% 115% 95% amount curatives 17 3% Vestenamer powder <500 μm 15% 93% 104% 102% 116% 97% plus high amount curatives 19 3% Vestenamer powder <125 μm 15% 86% 104% 102% 115% 95% plus high amount curatives 20 High amount curatives (whithout 15% 99%  98%  97% 100% 98% Vestenamer) 21 3% % Vestenamer cryogenic 15% 84% 106% 109% 106% 94% powder <400 μm pre-mix plus low amount curatives 22 3% % Vestenamer cryogenic 15% 83% 104% 103% 115% 95% powder <400 μm pre-mix plus high amount curatives 23 1% organic peroxide Trigonox 29 15% 95% 101% 102% 104% 100%  24 2.3% NR latex (dry) plus 0.6% 15% 94% 101% 103% 115% 97% peroxide Trigonox 29 25 10% Alpha wax SX70 plus 1% 15% 73% 100% 114% 106% 99% predispersed sulphur (active content) 26 10% Alpha Carisma 62 SX70 wax 15% 71%  99% 112% 104% 101%  plus 1% predispersed sulphur (active content) 27 10% Alpha Carisma Glossy wax 15% 73% 102% 111% 104% 103%  plus 1% predispersed sulphur (active content) 28 10% Alpha SX 5928 wax plus 1% 15% 69%  98% 108% 106% 101%  predispersed sulphur (active content) 29 2.5% NR latex premix with 15% 94%  99% 104% 112% 95% colloidal sulphur colloidal ZnO 30 1.6% colloidal sulphur (active 15% 96%  98%  95% 111% 97% content) 31 1.8% peroxide Luperox 231M90E 15% 98% 100% 100% 107% 96% (active content) 32 1% Luperox 231M50 E ( active 15% 98% 101% 101% 104% 98% content) 33 1% Trinseo SBR latex K1 15% 91% 105% 107% 103% 98% 34 1% Trinseo SBR latex K2 15% 99%  97%  97%  96% 103%  35 1% Trinseo SBR latex K3 15% 96% 102% 105% 100% 101%  36 1% Trinseo SBR latex K4 15% 94% 105% 107% 103% 98% 37 1% Trinseo SBR latex K5 15% 98%  99%  97% 105% 98% 38 2.8% Silane (Si69) + 2.8% BDGA + 15% 82% 112% 116% 112% 93% 0.6% SBR latex (dry) + 8.3% Alpha Carisma Glossy 39 9% Silane (Si69) 15% 96%  97%  99% 117% 90% 40 4.5% Silane (Si69) + 4.5% BDGA 15% 84%  96% 108% 110% 98% 41 0.6% Silane (Si69) + 2% NR latex 15% 90% 101% 102% 108% 97% (dry) 42 0.6% Trigonox 29-C50 (active 15% 92% 100% 103% 115% 97% content) + 2% NR latex (dry) 43 5.9% Silane (Si69) plus 6% NR latex 15% 84% 122% 116% 112% 94% (dry) Improve- ment Tensile Payne Ulitmate Tear Abrasion Rating, Extrude to Sample Strength Effect M100 M300 Elongation Strength Loss Ave, % solid Ref 125% 70% 117% 121% 110% 131% 62% 100.0 N/A Ref 100% 100%  100% 100% 100% 100% 100%  0.0 no 1 102% 98% 101% 101%  99% 102% 95% 7.9 no 2 104% 94% 103% 106% 101% 101% 94% 15.4 no 3 107% 92% 104% 108% 101% 106% 92% 22.0 no 4 106% 90% 105% 107% 100% 109% 91% 24.8 no 5 105% 87% 106% 107% 103% 108% 92% 27.2 no 6 104% 84% 105% 108%  98% 115% 89% 28.7 no 7 111% 74% 109% 111% 110% 121% 81% 65.7 no 8 102% 99%  99%  98% 105% 103% 98% 10.2 yes 9 105% 83% 104% 106% 103% 108% 94% 27.2 yes 10 101% 99% 102% 103% 107% 120% 82% 29.5 yes 11 117% 75% 109% 110% 101% 121% 72% 59.1 yes 12 115% 76% 112% 110%  88% 125% 74% 61.4 yes 13 106% 90% 105% 107% 102% 109% 89% 27.2 no 14 105% 95% 104% 104% 105% 104% 100%  19.3 no 15 105% 84% 104% 105% 105% 108% 94% 27.2 no 16 102% 75% 115% 114%  95% 117% 69% 53.9 yes 17  96% 79% 113% 112%  93% 114% 72% 42.9 yes 19  99% 75% 115% 113%  95% 117% 71% 52.4 yes 20  97% 106%  105% 104%  92% 103% 98% −2.0 no 21 105% 80% 106% 108% 101% 103% 93% 36.6 yes 22 102% 95% 115% 114% 102% 118% 69% 51.6 yes 23 102% 98% 101% 101% 100% 102% 95% 9.8 no 24 107% 83% 104% 106% 103% 112% 70% 42.1 yes 25 103% 91% 106% 107% 110% 107% 87% 40.6 no 26 101% 96% 103% 104% 115% 102% 90% 32.3 no 27  98% 101%   99% 101% 111%  95% 106%  15.0 no 28 101% 96% 106% 108% 107% 109% 100%  30.3 no 29 111% 78% 110% 112% 101% 118% 71% 50.8 yes 30 113% 89% 109% 111% 102% 108% 60% 41.3 no 31 104% 87% 111% 110%  97% 117% 69% 37.8 no 32 100% 93% 105% 106% 106% 123% 74% 32.7 no 33 104% 95% 104% 103% 105% 107% 98% 22.0 no 34  94% 106%   95%  97%  92% 103% 105%  −16.5 no 35  98% 102%  100%  99%  98% 103% 104%  0.8 no 36 103% 95% 104% 103% 111% 107% 93% 24.8 no 37  94% 106%   95%  97%  92% 103% 71% 3.5 no 38 112% 75% 115% 117%  90% 110% 65% 66.5 no 39 106% 69% 118% 125%  94% 115% 60% 61.4 no 40 109% 86% 104% 107% 112% 108% 89% 38.2 no 41 106% 90% 105% 107% 102% 109% 81% 32.3 yes 42 107% 83% 104% 106% 107% 112% 75% 42.1 yes 43 120% 74% 109% 111% 110% 121% 68% 79.1 yes

TABLE-US-00003 TABLE 3 Composition of test recipe PPHR MATERIAL WEIGHT UNIT % 100 Natural Rubber 29.04 grams 52.8 TSR-10 5 Zinc oxide 1.45 grams 2.6 3 Stearic acid 0.87 grams 1.6 50 N375 carbon black 14.51 grams 26.4 28.4 MRP sample 8.24 grams 15.0 2.5 Sulphur 0.72 grams 1.3 0.6 TBBS 0.17 grams 0.3 189.5 Total: 55.00 grams 100 Batch weight: 55.00

[0058] Several additional test examples (see Table 3 and 4) were prepared out to investigate the performance of the rubber composition.

[0059] The test examples were compared with a so-called test recipe. The composition of the test recipe (according to ASTM D3191, ASTM D3191 excludes MRP) is shown in Table 3.

[0060] The reference MRP sample is Cryofine 80 (Kargro) mesh, i.e. a cryogenically ground Micronized Rubber Powder produced exclusively from pre-selected end of life whole truck tyres, compliant with ASTM D5603 Class 80 1*.

[0061] Samples #1-#11 (see Table 4) were prepared by mixing the components mentioned in Table 3 together with specific components. The rubber composition thus obtained was tested for several parameters, such as Mooney viscosity, Rheology Scorch time, ts2, Rheology T90, Rheology Delta 5, Tangent Delta, Tensile Strength, Payne Effect, M100, M300, Ultimate Elongation, Tear Strength, and Abrasion Loss.

[0062] The results of these tests are shown in Table 4. On basis of these performance parameters an average improvement rate was calculated (%).

TABLE-US-00004 TABLE 4 gy MRP M y S Rheology Rheology Sample Description C V ty , ts2 T90 Delta S Ref Reference compound ASTM D3191 (target 0 83% 120% 120% 11 % values) Ref MRP Reference compound ASTM D3191 15% 100%  10 % 100% 100% (nor  values)  MRP 1 0.5% U  VN3 + 2% 15% 93% 100% 104% 103% 2 0.5% U  VN3 + 3% 15% 91% 108% 111% 104% 3 0.5% U  VN3 + 4% 15% 91% 110% 112% 111% 4 0.5% U  VN3 + 5% 15% 89% 112% 115% 110% 5 0.5% U  VN3 + 6% 15% 8 % 112% 115% 116% 6 0.5% U  VN3 + 1%  8113 + 2% 15% 92% 107% 106% 105% 7 0.5% U  VN3 + 1%  8113 + 3% 15% 90% 10 % 110% 105% 8 0.5% U  VN3 + 1%  8113 + 4% 15% 90% 111% 114% 111% 9 0.5% U  VN3 + 1%  8113 + 5% 15% 89% 112% 116% 112% 10 0.5% U  VN3 + 1%  8113 + % 15% 88% 11 % 116% 112% 11 1% Coup   113 + 9 15% 87% 113% 11 % 114% Improvement Tangent Tensile Payne Ulitmate Tear Abrasion Sample Delta Strength Eff ct M100 M300 Elongation Strength Loss Ave Ref 90% 125% 70% 117% 121% 130% 131% 62% 100.0 Ref MRP 100%  100% 100%  100% 100% 100% 100% 100%  0.0 1 98% 106% 88% 106% 103% 108% 100% 7% .7 2 95% 117% 79% 111% 107% 110% 108% 90% 4.2 3 95% 11 % 7 % 110% 108% 114% 120% 88% .1 4 94% 118% 74% 111% 10 % 119% 118% 82% .8 5 92% 111% 74% 113% 118% 110% 116% 81% 5.0 6 93% 106% 83% 106% 107% 122% 104% 99% 36.3 7 94% 117% 7 % 109% 113% 126% 10 % 89% 34.0 8 94% 117% 75% 113% 11 % 124% 109% 81% 64. 9 94% 120% 74% 113% 120% 123% 11 % 80% 71. 10 94% 1 % 74% 115% 122% 112% 11 % 7 % 71.9 11 92% 121% 74% 114% 120% 120% 126% 7 % 78.8 * MRP MRP indicates data missing or illegible when filed

[0063] In Table 4 Ultrasil VN3 is SiO.sub.2, synthetically produced amorphous silicon dioxide (Evonik), Coupsil 8113 is precipitated silica, surface-modified with organosilane Si 69 (Evonik) and Silane (Si69) is a polyfunctional (polysulphide) silane (Evonik).

[0064] From Table 4 one will see that samples #1-5 (containing 0.5% Ultrasil VN3 and between 2-6% Silane (Si69)) show an improvement rating of between 19.7% and 65%. Samples #6-10 (containing 0.5% Ultrasil VN3, 1% of Coupsil 8113 and between 2-6% Silane (Si69)) show an improvement rating of between 36.5% and 71.9%. Sample #11 (containing 1% Coupsil 8113 and 5% Silane (Si69)) shows the best improvement rating of 78.8%.

[0065] The present inventors found that Ultrasil VN3 is a very effective dusting agent for deagglomerating the rubber particles after the cryogenic grinding process. Deagglomeration needs to take place in order to effectively sieve the fraction having the desired particle size distribution (D95<180 microns) and to screen out oversize particles for further processing. Clearly, when powder particles are stuck together they cannot be classified according to their size. The process of deagglomeration is also important to maximize the surface area of the powder to ensure that the activation chemicals have the possibility to coat the maximum amount of the powder's surface area. Ultrasil VN3—being highly receptive to hydrophobation and condensation reaction with silane Si69—also plays a role in the activation step.

[0066] The present inventors found that Coupsil 8113 has a similar effectiveness as Ultrasil VN3 as a dusting/deagglomeration agent. However, Coupsil 8113 plays a more significant role than Ultrasil VN3 as an activation chemical because it is coated with about 11% of Si69. Therefore, for example, Coupsil 8113 can fully replace Ultrasil VN3 as a dusting agent, meaning that VN3 would not need to be used at all.

[0067] The present inventors found that a combination of Coupsil 8113 (with a concentration of 1 wt. %) and Si69 at 4 wt. % concentration provides good results. Si69 also works well at 6 wt. % concentration without using any Coupsil 8113 but with using the dusting agent (0.25-0.5 wt. % of Ultrasil VN3) but such option is less costs attractive than adding 1 wt. % Coupsil 8113+4 wt. % Si69.