Rubber process oil

Abstract

RUBBER PROCESS OIL The invention provides a rubber process oil comprising a hydrocarbon fluid comprising paraffinic hydrocarbons, naphthenic hydrocarbons, or a mixture thereof, wherein said hydrocarbon fluid has a kinematic viscosity at 100˚C of less than 10 cSt, and wherein said hydrocarbon fluid comprises a re-refined or recycled oil. The invention also provides a process for the production of a rubber composition said process comprising the steps of combining a natural or synthetic rubber with a rubber process oil comprising a hydrocarbon fluid comprising paraffinic hydrocarbons, naphthenic hydrocarbons, or a mixture thereof, wherein said hydrocarbon fluid has a kinematic viscosity at 100˚C of less than 10 cSt, and wherein said hydrocarbon fluid comprises a re-refined or recycled oil.

Description

[0001] RUBBER PROCESS OIL

[0002] Field of the Invention

[0003] This invention relates to a rubber process oil composition and a process for producing rubber articles using said oil .

[0004] Background of the invention

[0005] Process oils are hydrocarbon mixtures that boil in the same temperature range as lubricant base oils . Instead of being used as the base fluid in a lubricant, process oils have a wide range of industrial applications , for example as a rubber process oil . In the production of rubber articles , oils can be added to the rubber-forming polymer during manufacture, when they are termed extender oils ; or to the rubber compound, when they are termed rubber process oils . These oils are employed during rubber processing for reducing the mixing temperature, prevent scorching and to decrease the viscosity of the rubber, thereby facilitating the milling operations and general workability of the rubber compound and to aid the dispersion of fillers and modify the physical properties of rubber compounds . An oil used in the manufacture of rubber compounds should have high degree of miscibility or solubility with rubber to act as good process oil .

[0006] The rubbers to be processed include natural rubbers and various types of synthetic rubbers . Of these, a large amount of natural rubber and styrene-butadiene rubber (SBR) are used . Therefore, typically, a rubber process oil containing a large amount of aromatic hydrocarbon is used in order to have high affinity with the rubber to be processed . Conventionally, aromatics-based and high viscosity (typically with a kinematic viscosity at 100 ° C of 10 cSt or more and usually considerably higher) , naphthene-based oils are used as rubber processing oils for rubbers such as SBR and the like . Aromatic-based rubber process oils have excellent compatibility with rubber but may contain an undesirably large amount of polycyclic aromatics . There has been considerable effort to reduce the use of such harmful chemicals within rubber processing, such as in the rubber processing oils described in US 6248929 and US2015 / 0068951 . However, further adaptations and improvements in the process oils used in rubber processing are always desirable and sought after .

[0007] In all technology areas , it is necessary to consider the carbon footprint of a product and to try and ensure that raw materials are re-used and recycled where possible . The production of rubber products , including tires , is an area in which there is a focus on reducing the carbon footprint .

[0008] Summary of the Invention

[0009] The present invention provides a rubber process oil comprising a hydrocarbon fluid comprising paraffinic hydrocarbons , naphthenic hydrocarbons , or a mixture thereof , wherein said hydrocarbon fluid has a kinematic viscosity at 100 ° C of less than 10 cSt, and wherein said hydrocarbon fluid comprises a re-refined or recycled oil .

[0010] The present invention also provides a process for the production of a rubber composition, said process comprising the steps of combining a natural or synthetic rubber with a rubber process oil comprising a hydrocarbon fluid comprising paraffinic hydrocarbons , naphthenic hydrocarbons , or a mixture thereof , wherein said hydrocarbon fluid has a kinematic viscosity at 100 ° C of less than 10 cSt, and wherein said hydrocarbon fluid comprises a re-refined or recycled oil . Detailed Description of the Invention

[0011] One or more specific embodiments of the present disclosure will be described below . These described embodiments are examples of the presently disclosed techniques . Additionally, in an effort to provide a concise description of these embodiments , not all features of an actual implementation may be described in the specification .

[0012] When introducing elements of various embodiments of the present disclosure, the articles "a, " "an," and "the" are intended to mean that there are one or more of the elements . The terms "comprising, " "including, " and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements . Additionally, it should be understood that references to "one embodiment" or "an embodiment" of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features .

[0013] In the context of the present invention, in a case where a composition comprises two or more components , these components are to be selected in an overall amount not to exceed 100 wt% .

[0014] The present inventors have found that a hydrocarbon fluid that is a re-refined or recycled oil and has a kinematic viscosity at 100 ° C of less than 10 cSt provides an excellent rubber process oil . This provides an advantageous oil for this use with a reduced carbon footprint . It also provides a use for a product stream that is currently under-utilised .

[0015] A re-refined or recycled oil is one that has previously been used as some form of functional fluid such as a lubricating oil composition . Examples of lubricating oil compositions include, but are not limited to, passenger car engine oils , heavy duty diesel engine oils , transmission lubricants , turbine oils , air compressor lubricants , hydraulic fluids , gear oils , greases , transformer oils , marine lubricants , and the like .

[0016] The types of functional fluids that are used in any re-refined or recycled oil will depend on the fluids available for processing in any market . Currently, most re-refined or recycled oils were originally used as engine oils , turbine oils or hydraulic fluids .

[0017] In their original use, such functional fluids will comprise one or more base oils and one or more additives in order to perform their desired function . Further, during use , contaminants , such as water, decomposition products and products of wear, may accumulate in the fluid . Recycling or re-refining said fluids will require one or more processes in order to remove any remaining additives and contaminants and to produce an oil with a suitable viscosity range .

[0018] Technologies such as distillation, thermal deasphalting, or solvent (often propane) de-asphalting are used as recycling technologies for used functional fluids . The intermediate products created by recycling technologies are unfinished and typically unsuited for use as lubricants without further improvement . Finishing technologies such as clay treatment , hydrotreatment ( see, for example, EP3921390A1 , US11034895B1 ) , or solvent extraction (as described in CN107574012A) may then be used to "finish" the quality of the intermediates into marketable base oils . When a recycling technology and a finishing technology are coupled together, they are generally referred to as a re-refining technology. A further, pre-treatment , step may also be used to remove sludge, water and additive metals before recycling occurs . The hydrocarbon fluid comprises a re-refined or recycled oil . Preferably, the hydrocarbon comprises at least 50wt% , more preferably at least 70wt% , even more preferably at least 80wt% , even more preferably at least 90wt% , even more preferably at least 95wt% , most preferably at least 99wt% of re-refined or recycled oil . In a particularly preferred embodiment, the hydrocarbon fluid consists essentially of re-refined or recycled oil . The rubber process oil preferably contains no more than 10wt% , more preferably no more than 5wt% and most preferably essentially no virgin base oil .

[0019] The amount of paraffinic and naphthenic hydrocarbons present in the hydrocarbon fluid will depend on the functional fluids used to produce the re-refined or recycled oil . Typically, the hydrocarbon fluid will contain an amount of paraffinic hydrocarbons in the range of from 40 to 100 wt% , based on the overall weight of the hydrocarbon fluid . Also typically, the hydrocarbon fluid will contain an amount of naphthenic hydrocarbons in the range of from 0 to 55 wt% based on the overall weight of the hydrocarbon fluid . Aromatic hydrocarbons may also be present in the hydrocarbon fluid, typically at an amount of no more than 10wt% , based on the overall weight of the hydrocarbon fluid . Preferably less than 3wt% of polycyclic aromatics are present in the hydrocarbon fluid, based on the overall weight of the hydrocarbon fluid .

[0020] The kinematic viscosity at 100 ° C of the hydrocarbon fluid is less than 10 cSt measured according to ASTM D445. Preferably, the kinematic viscosity at 100 ° C is at least 2 . 0 cSt , more preferably at least 4 . 0 cSt .

[0021] The present invention also provides a process for the production of producing a rubber composition in which a natural or synthetic rubber is combined with the rubber process oil . The phrase "natural or synthetic rubber" as used herein is intended to include both natural rubber and its various raw and reclaimed forms as well as various synthetic rubbers . In the description of this invention, the terms "rubber composition" is used to refer to rubber which has been blended or mixed with various ingredients and materials , and such terms are well known to those having skill in the rubber mixing or rubber compounding art .

[0022] As well as the natural or synthetic rubber and the rubber process oil, the rubber composition may contain any conventional additives and fillers . The term "phr" as used herein, and according to conventional practice, refers to "parts by weight of a respective material per 100 parts by weight of the natural or synthetic rubber" .

[0023] The rubber composition of the present invention may contain carbon black, for example . Any carbon black commonly used in the rubber and, in particularly, the tire industry may be used . Examples include N134 , N110 , N220 , N234 , N219 , N339, N330 , N326 , N351 , N550 , and N762 . In the case where carbon black is used, the amount of carbon black is preferably 1 phr or 15 phr or more, more preferably 30 phr or more, but is preferably 100 phr or less , more preferably 80 phr or less .

[0024] The rubber composition may contain from about 10 to 200 phr of silica . In the case where silica is present, a silane coupling agent may also be added .

[0025] Non-limiting examples of fillers other than carbon black and silica include those commonly used in the rubber and particularly the tire industry, including, for example , inorganic fillers such as aluminium hydroxide, talc, mica , magnesium oxide, magnesium sulfate, titanium white , titanium black, calcium oxide, calcium hydroxide , magnesium aluminum oxide, clay, pyrophyllite, bentonite , aluminum silicate, magnesium silicate, calcium silicate , aluminum calcium silicate, magnesium silicate , silicon carbide , zirconium, and zirconium oxide; and organic fillers such as short fibers and cellulose nanofibers .

[0026] It is readily understood by those having skill in the art that the rubber composition would be compounded by methods generally known in the rubber compounding art, such as mixing the natural or synthetic rubber with various commonly used additive materials such as , for example , sulfur donors , curing aids , such as activators and retarders and processing additives , resins including tackifying resins and plasticizers , fillers , pigments , fatty acid, zinc oxide, waxes , antioxidants and antiozonants and peptizing agents . As known to those skilled in the art, depending on the intended use of the rubbers composition, the additives mentioned above are selected and commonly used in conventional amounts .

[0027] The mixing of the rubber composition can be accomplished by methods known to those having skill in the rubber mixing art . For example, the ingredients are typically mixed in at least two stages , namely, at least one non-productive stage followed by a productive mix stage . The final curatives including sulfur-vulcanizing agents are typically mixed in the final stage which is conventionally called the "productive" mix stage in which the mixing typically occurs at a temperature, or ultimate temperature, lower than the mix temperature ( s ) than the preceding non-productive mix stage ( s ) . The terms "non¬ productive" and "productive" mix stages are well known to those having skill in the rubber mixing art . The rubber composition may be subj ected to a thermomechanical mixing step . The thermomechanical mixing step generally comprises a mechanical working in a mixer or extruder for a period of time suitable in order to produce a rubber temperature between 140 °C and 190 °C . The appropriate duration of the thermomechanical working varies as a function of the operating conditions , and the volume and nature of the components . For example, the thermomechanical working may be from 1 to 20 minutes .

[0028] The rubber composition of the present invention may be used in any suitable use known for rubber compositions in the art . However, preferably, the rubber composition of the present invention is used in tire applications . The rubber composition of the present invention is preferably used for treads of tires . It may also be used for various tire components such as sidewalls , base treads, undertreads , clinch apexes , bead apexes , breaker cushion rubbers , carcass cord topping rubbers , insulations , chafers , innerliners , and side reinforcing layers of run¬ flat tires . The type of tire to which the rubber composition may be applied is preferably a pneumatic tire . Besides , the rubber composition may also be applied to pneumatic or non-pneumatic tires of passenger vehicles, trucks and buses , or motorcycles .

[0029] The invention will now be further illustrated by reference to the following non-limiting examples .

[0030] Example 1 - Tread

[0031] A virgin rubber process oil was formulated into a tread compound and used as a reference for comparison . Various re-refined rubber process oil combinations were formulated into multiple tread compounds , each with different loading of additives and fillers . The formulations are shown in Table 1 .

[0032] The following rubber process oils and additives were used .

[0033] V25 : a virgin process oil containing primarily hydrotreated naphthenic base oils and heavy residuals , 25 cSt @ 100 ° C and 550 cSt @ 40 ° C RR7 : a re-refined base oil containing primarily paraffinic molecules , 7 cSt @ 100 ° C and 43 cSt @ 40 ° C

[0034] RR3 : a re-refined based oil containing primarily paraf finic molecules , 3 cSt @ 100 ° C and 13 cSt @ 40 ° C SLR-4 602 - styrene-butadiene rubber ( ex . Synthos )

[0035] CB-25 - neodymium butadiene rubber ( ex Arlanxeo )

[0036] N330 - carbon black

[0037] Zeosil 1165MP - silica ( ex . Solvay)

[0038] SCA98 - organos ilane ( ex . Struktol )

[0039] Akrowax 195 - wax ( ex . Akrochem)

[0040] DPG - N , N' -diphenylguanidine

[0041] Zoco 104 - zinc oxide ( ex . Zochem)

[0042] SA29 - stearic acid ( ex . VStearin )

[0043] TBBS - accelerator compound

[0044] RMS - rubber ma ker' s sulfur

[0045] In formulations B to L , RR3 and RR7 were mixed in different proportions to achieve various viscos ities , showcas ing a broad number of proof points . ASTM D7152 can be used to calculate the kinematic viscos ity of these mixture s , as needed .

[0046] The different compounds shown in Table 1 , have the following key properties for each compound :

[0047] Compound A : Control with V25 reference virgin oil Compound B : 100 % RR7 with -3 . 4 phr carbon black ( CB ) Compound C : 50 / 50 mix of RR3 and RR7 with +3 . 6 phr CB Compound D : 10 / 90 mix of RR3 and RR7 with +1 . 6 phr CB Compound E : 25 / 75 mix of RR3 and RR7 with +1 . 6 phr CB Compound F : 40 / 60 mix of RR3 and RR7 with +1 . 6 phr CB Compound G : 40 / 60 mix of RR3 and RR7 with cure adj ustments and +1 . 6 phr CB

[0048] Compound H : 40 / 60 mix of RR3 and RR7 with cure adj ustments and +1 . 6 phr CB

[0049] Compound I : 10 / 90 mix of RR3 and RR7 with cure adj ustments and +3 . 6 phr CB Compound J : 10 / 90 mix of RR3 and RR7 with cure adj ustments and - 4 . 4 phr CB

[0050] Compound K : 10 / 90 mix of RR3 and RR7 with cure adj ustments and - 4 . 4 phr CB

[0051] Compound L : 10 / 90 mix of RR3 and RR7 with cure adj ustments and - 4 . 4 phr CB

[0052] The relative performance propertie s of the formulations given in Table 1 are shown in Table 2 . The se measurements were obtained according to ASTMD412 (Tensile strength, stiffnes s , ultimate elongation and toughne s s ) or using a standard dynamic mechanical analyser . The value s given are comparative to the value measured for compound A, with values higher than 100 better than compound A and those lower worse than for compound A . It can be seen that a variety of different rubbers with different propertie s can be formed using the re-refined hydrocarbon fluids . These relative measurements may be used by formulators to optimize specif ic attributes , such as rolling resistance versus dry traction . Compound ID A B C D E F G H I J K L SLR-4602 75 75 75 75 75 75 75 75 75 75 75 75 CB-25 25 25 25 25 25 25 25 25 25 25 25 25

[0053]

[0054] N330 6.4 3 10 8 8 8 8 8 10 2 2 2 Zeosil 1165MP 80 80 80 80 80 80 80 80 80 80 80 75 SCA98 6.4 6.4 6.4 6. 4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6

[0055] V25 Oil 37.5

[0056] RR3 Oil 18.75 3.75 9.375 15 15 15 3.75 3.75 3.75 3.75 RR7 Oil 37.5 18.75 33.75 28.125 22.5 22.5 22.5 33.75 33.75 33.75 33.75 Akrowax 195 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 DPG 2 2 2 2 2 2 2 2 2 2 2 2

[0057] Zoco 104 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 TMQ 2 2 2 2 2 2 2 2 2 2 2 2

[0058] SA29 1 1 1 1 1 1 1 1 1 1 1 1

[0059] RMS 1.4 1.4 1.4 1.4 1.4 1.4 1.7 2 2 2 2.25 2.25 TBBS 1.7 1.7 1.7 1.7 1.7 1.7 1.7 1.7 1.7 1.7 1.7 1.7 TOTAL 242.4 239 246 244 244 244 244.3 244.6 244.6 238.6 238.85 233.45

[0060]

[0061] Table 2

[0062] Ccrpmrc..

[0063] ID M*

[0064] Tilnees in

[0065] Shttreng

[0066] | | 120 123 111 135 129 111 102 103 100 Sffitness

[0067] o m

[0068] © (M200) o © ®

[0069] 100 Ulittaae

[0070] Elitongaon

[0071] <» co I | I I | | 86100 Th Mougness* »

[0072] r- CO | R 107 117 139 100lli 3ong ®

[0073] Ritessance

[0074] | 111 110 100 108

[0075] H <* M3 co M3

[0076] © r- CP S at

[0077] Wte

[0078] Titracon | | S 117 115 113 116 113 119 100now as © co tf)

[0079] r- £ STI TTT £TT Titracon TOT 00T 001

[0080] o tn o co

[0081] r-l 60T SOT ch | Sfrt

[0082] Ju co © tn !n a»

[0083] m

[0084] M ©

[0085] © r- ©

[0086] u

[0087] 00T

[0088] Q © eH M3

[0089] © CO

[0090] O ©

[0091] m o> £

[0092] M>

[0093] « O co cn

[0094] C

[0095] • oH

[0096] p

[0097] o

[0098] Q H

[0099]

[0100] Example 2 - Innerliner

[0101] A virgin rubber process oil was formulated into an innerliner compound and used as a reference for comparison . Various re-refined rubber process oil combinations were formulated into multiple interliner compounds , each with different loading of additives and fillers . The formulations are shown in Table 3.

[0102] The following rubber process oils and additives were used .

[0103] V4 : a virgin process oil containing a maj ority hydrotreated paraffinic base oils , with the remaining molecules being naphthenic, with no meaningful amount of aromatics (<0. 1% ) , 4 cSt @ 100 ° C and 22 cSt @ 40 ° C

[0104] RR7 and R70 as in Example 1

[0105] BB2030 - butyl rubber (ex . Lanxess )

[0106] N660 - carbon black

[0107] MBTS - mercaptobenzothiazole

[0108] Phenol formaldehyde resin

[0109] magnesium oxide (MgO)

[0110] stearic acid

[0111] zinc oxide

[0112] sulfur .

[0113] In formulations B to L, RR3 and RR7 were mixed in different proportions to achieve various viscosities , showcasing a broad number of proof points . ASTM D7152 can be used to calculate the kinematic viscosity of these mixtures, as needed .

[0114] The different compounds tested shown in Table 3 have the following key properties for each compound:

[0115] Compound A: Control with V4 reference virgin oil Compound B : 50 / 50 mix of RR3 and RR7 with adj usted cure Compound C : 50 / 50 mix of RR3 and RR7 with adj usted cure Compound D : 30 / 70 mix of RR3 and RR7 with adj usted cure Compound E : 40 / 60 mix of RR3 and RR7 with adj usted cure Compound F : 100% RR3 with adj usted cure and +5phr carbon black (CB)

[0116] Compound G : 75 / 25 mix of RR3 and RR7 with adj usted cure and +5phr CB

[0117] Compound H : 60 / 40 mix of RR3 and RR7 with adj usted cure and +3phr CB

[0118] Compound I : 25 / 75 mix of RR3 and RR7 with adj usted cure and +2phr CB

[0119] Compound J : 10 / 90 mix of RR3 and RR7 with adj usted cure and +2phr CB

[0120] Compound K: 15 / 85 mix of RR3 and RR7 with adj usted cure and +2phr CB

[0121] Compound L : 25 / 75 mix of RR3 and RR7 with adj usted cure and +2phr CB

[0122] The relative performance properties of the formulations given in Table 3 are shown in Table 4 . As with Example 1 , the measurements were obtained using ASTMD412 or using a standard dynamic mechanical analyser . Again, it can be seen that a variety of different rubbers with different properties can be formed using the rerefined hydrocarbon fluids . These relative measurements may be used by formulators to optimize specific attributes . Compound ID A B C D E F G H I J K L BB2030 100 100 100 100 100 100 100 100 100 100 100 100 N660 60 60 60 60 60 65 65 63 62 62 62 62

[0123]

[0124] V4 Oil 11

[0125] RR3 Oil 5.5 5.5 3.5 4.5 11 8.5 6.5 2.5 1 1.5 2.5 RR7 Oil 5.5 5.5 7.5 6.5 2.5 4.5 8.5 10 9.5 8.5 Phenol 4 4 4 4 4 4 4 4 4 4 4 4 Formaldehyde

[0126] Resin

[0127] MgO 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 Stearic Acid 2 2 2 2 2 2 2 2 2 2 2 2 Zinc Oxide 1 1 1 1 1 1 1 1 1 1 1 1 MBTS 1.5 1.5 1.3 1.3 1.4 1.3 1.3 1.3 1.3 1.3 1.3 1.3 Sulfur 0.5 0.3 0.3 0.5 0.4 0.1 0.1 0.1 0.1 0.1 0.5 0.5 TOTAL 180.2 180 179.8 180 180 184.6 184.6 182.6 181.6 181.6 182 182

[0128]

[0129] Compound ID A B C D E F G H I J K L Tensile 100 97 94 100 98 89 86 87 86 86 109 105 Strength Stiffness 100 95 91 100 95 93 91 84 84 79 116 112

[0130]

[0131] (M300)

[0132] Ultimate 100 98 98 97 101 90 89 97 101 95 92 94 Elongation

[0133] Toughness 100 94 88 94 95 76 73 80 81 77 95 95 Fatigue to 100 264 73 79 110 263 363 363 363 363 75 85 Failure

[0134] Adhesion to 100 99 99 121 100 100 109 100 107 110 101 96 Ply Skim

[0135] Oxygen 100 93 93 96 94 90 95 94 137 91 86 102 T r ansmi 3 s ion

[0136]

[0137] Rate

Claims

C L A I M S1. A rubber process oil comprising a hydrocarbon fluid comprising paraffinic hydrocarbons , naphthenic hydrocarbons , or a mixture thereof , wherein said hydrocarbon fluid has a kinematic viscosity at 100 ° C of less than 10 cSt, and wherein said hydrocarbon fluid comprises a re-refined or recycled oil .2 . A rubber process oil as claimed in Claim 1 , wherein the rubber process oil contains essentially no virgin base oil .

3. A rubber process oil as claimed in Claim 1 or Claim 2 , wherein the rubber process oil is a re-refined transformer oil .4 . A process for the production of a rubber composition said process comprising the steps of combining a natural or synthetic rubber with a rubber process oil according to any one of Claims 1 to 3 .

5. A process for the preparation of a rubber article as claimed in Claim 4 , comprising the step of compounding in the range of from 10 to 200 parts by weight of the rubber process oil with 100 parts by weight of the natural or synthetic rubber .

6. A process as claimed in Claim 4 or Claim 5 , wherein the rubber composition is used in a tire .7 . A rubber composition comprising rubber and the rubber process oil as claimed in any one of claims 1 to 3.

Images