LU500856B1 - Masterbatch of silica and one or more process oils to produce rubber formulation for tires - Google Patents

Abstract

The disclosure provides a masterbatch comprising silica and one or more process oils, wherein the one or more process oils comprise one or more aromatic hydrocarbons that include one or more polyaromatic hydrocarbons, wherein at least one of the polyaromatic hydrocarbons is benzo(a)pyrene, the masterbatch being remarkable in that the one or more process oils contain less than 1 mg per kg of benzo(a)pyrene according to Standard EN16143:2013; and in that the content of the one or more process oils is ranging between 20 wt.% and 80 wt.% of the total weight of said masterbatch, the remaining part being silica. A process for making such masterbatch and a process for making a rubber formulation comprising such masterbatch are also described.

Description

Description

MASTERBATCH OF SILICA AND ONE OR MORE PROCESS OILS TO PRODUCE

RUBBER FORMULATION FOR TIRES

Field of the disclosure

The present disclosure relates to a masterbatch of silica and one or more process oils.

Background of the disclosure

Process oils or extender oils are hydrocarbon mixtures that boil in the same temperature range as lubricant base oils and are derived from petroleum distillates by solvent extraction. Rubber process oils are added to natural and synthetic rubbers for several reasons, for example, to reduce mixing temperatures during processing and prevent scorching or burning of the rubber polymer when it is being ground to a powder, to decrease the viscosity of the rubber and thereby facilitate milling, extruding and general workability of the rubber compound (which also includes several additional components), to reduce mill and calender shrinkage, to aid the dispersion of fillers, to modify the physical properties of the vulcanised and/or finished rubber compounds, and for other reasons which are well-known to those skilled in the art.

Process oils, and aromatic process oils, such as distillate aromatic extracts (DAE), comprise high levels of polycyclic aromatic hydrocarbons (PAH) that are classified as carcinogenic according to the European legislation. The list of PAH comprises benzo(a)pyrene (BaP), benzo(e)pyrene (BeP), benzo(a)anthracene (BaA), chrysen (CHR), benzo(b)fluoranthene (BbFA), benzo(j)fluoranthene (BjFA), benzo(k)fluoranthene (BkFA), dibenzo(a, h)anthracene (DBAhA). The REACH (Registration, Evaluation, Authorisation and restriction of CHemicals) regulation has defined a framework in which the process oils used for the production of tyres or part of tyres must not contain more than 1 mg/kg of BaP according to Standard

EN16143:2013 or more than 10 mg/kg of the sum of all listed PAH according to Standard

EN16143:2013 (see Regulation (EC) No 1907/2006 of the European parliament and the council). This corresponds to process oils having a content of polycyclic aromatic DMSO- extracts which is below 3 wt.% as measured by the Institute of Petroleum Standard

P346:1998.

To satisfy this legal framework, both RU2279466 and RU2313562 describe purification methods of petroleum distillates to remove at least a part of the PAH. Following the particular conditions described in these documents, process oils comprising 60-90 wt.% of aromatic hydrocarbons including between 1.5 wt.% and 2.9 wt% of PAH DMSO-extract can be LU500856 obtained.

To improve the properties of the elastomers, and the rubber in particular, silica as reinforcing fillers can be dispersed into the elastomer. Properties such as tensile strength, tear-resistance and abrasion resistance of the rubber can thus be improved. The dispersion of silica in the polymer can strongly influence the final properties of the rubber compounds.

US 6,086,669 describes free-flowing or dry particulate compositions comprising particulate amorphous precipitated silica, hydrocarbon process oil and organic carboxylic acid having from 2 to 30 carbon atoms. The hydrocarbon process oil and the organic carboxylic acid are sorbed on silica. The hydrocarbon process oil is present in the dry particulate composition in an amount from 10 wt.% to 70 wt.% based on the total weight of the particulate amorphous precipitated silica. The organic carboxylic acids are present in the dry particulate composition in an amount from 0.5 wt.% to 10 wt.% based on the total weight of the particulate amorphous precipitated silica and are necessary for improving the dispersion of the silica within the process oil. Any elastomer reinforced with such dry particulate composition has a less than 2% of white area, that means that it is indicative of an improved degree of silica dispersion within the elastomer.

Another way to enhance the dispersibility of the silica into the final rubber formulation is to overcome the natural acidity of the silica by functionalizing the silanol group with silane moieties that can then create a chemical bond with the rubber. This process is called the hydrophobization of silica, namely the conversion of hydrophilic silica into hydrophobic silica.

A process for making a masterbatch comprising hydrophobated silica, rubber and process oil has been described in US 2019/0263979. In the masterbatch described in this document, more silica than process oil is added.

On the other hand, the document of Null V., entitled “Safe Process Oils for Tires with Low

Environmental Impact’ (KGK Kautschuk Gummi Kunststoffe 52. Jahrgang, Nr.12/99) describes rubber formulation comprising treated distillate aromatic extracts (TDAE), mildly or medium extracted solvate (MES) or treated residual aromatic extracts (TRAE) as process oils, all meeting the threshold in which the content of PAH is less than 3 wt.% DMSO-extract according to IP346 method. A rubber formulation comprising 37.5 parts per hundred parts rubber (phr) of process oil and 70 phr of silica (Vulkasil®S) is described. Such document shows the importance of providing rubber formulation with non-carcinogenic process oils.

However, the preparation of such formulation requires the dosing and the addition of all the individual ingredients, namely about fifteen or so different components. There is therefore still a need to improve the compounding of rubber formulations in which a high dispersibility of LU500856 silica is searched.

Summary of the disclosure

According to a first aspect, the present disclosure provides a masterbatch comprising silica and one or more process oils, wherein the one or more process oils comprise one or more aromatic hydrocarbons that include one or more polyaromatic hydrocarbons, wherein at least one of the polyaromatic hydrocarbons is benzo(a)pyrene, the masterbatch being remarkable in that the one or more process oils contain less than 1 mg per kg of benzo(a)pyrene according to Standard EN16143:2013; and in that the content of the one or more process oils is ranging between 20 wt.% and 80 wt.% of the total weight of said masterbatch, the remaining part being silica.

It has been found that, in the field of rubber formulation, the furnishing of a masterbatch consisting in silica and one or more environmental-friendly process oils has numerous advantages, such as reducing the dosing time for the ingredients of the rubber formulation since the masterbatch is a single product consisting in already two ingredients of the rubber formulation, which has for effect to increase the overall productivity in the production of rubber compounds for tires. The mixing time is also reduced thanks to an improved distribution of the silica in the one or more process oils which, when mixed with the other ingredients of the rubber formulation, results in an improved distribution of the silica in the rubber itself. A better distribution of the ingredients allows to reduce the needs for mixing time since they are already correctly distributed into the masterbatch. The energy costs for mixing are thus reduced.

It was thus found that the masterbatch of the present disclosure offers the possibility to present a simple way to introduce silica as reinforcing filer in rubber formulation(s) while being environmentally safe and in accordance with the European legislation regarding the amount of carcinogenic component within the masterbatch.

Advantageously, the content of the one or more process oils in the masterbatch is ranging between 30 wt.% and 70 wt.%, more preferably between 40 wt.% and 60 wt.%; even more preferably between 45 wt. % and 55 wt. %.

Advantageously, the content of the one or more process oils is ranging between 45 wt.% and wt.% of the total weight of said masterbatch, the remaining part being silica. For example, the content of the one or more process oils is 50 wt.% of the total weight of said masterbatch and the content of said silica is 50 wt.% of the total weight of said masterbatch.

With preference, the masterbatch is a powder and/or has a tapped density ranging between LU500856 0.280 g/cm?® and 0.725 g/cm?® as determined in accordance with ISO787-11, more preferably between 0.300 g/cm® and 0.700 g/cm?®, even more preferably between 0.350 g/cm® and 0.650 g/cm?

One or more of the following features further advantageously defines the one or more process oils of the present disclosure: — The one or more process oils comprise at least one oil selected from treated distillate aromatic extract, treated residual aromatic extracts and/or mild extracted solvate. — The one or more process oils further comprise polar compounds in an amount ranging between 3 wt.% and 10 wt.% based on the total weight of the one or more process oils according to ASTM D2007; with preference, between at least 3 wt.% and below 10 wt.%, more preferably between at least 3 wt.% and below or equal to 7 wt.%. — For example, the polar compounds have an acid number of at most 0.05 mg KOH/g as determined according to ASTM D664, preferably of at most 0.01 mg KOH/g. For example, the polar compounds comprise sulfur, nitrogen and/or oxygen. — The one or more process oils further comprise saturated hydrocarbons in an amount ranging between 20 wt.% and 35 wt.% based on the total weight of the one or more process oils according to ASTM D2007, preferably ranging between 25 wt.% and 30. wt.%. For example, said saturated hydrocarbons comprise paraffinic and/or naphthenic hydrocarbons. — The one or more process oils have a density ranging between 0.940 g/ml and 0.975 g/ml as determined by ASTM D4052, preferably between 0.945 g/ml and 0.970 g/ml, more preferably between 0.950 g/ml and 0.965 g/ml. — The one or more aromatic hydrocarbons are in an amount ranging between 55 wt.% and 75 wt.% based on the total weight of the one or more process oils according to ASTM

D2007, preferably ranging between 60 wt.% and 73 wt.%. — The one or more polyaromatic hydrocarbons further comprise, in addition of benzo(a)pyrene, one or more additional polyaromatic hydrocarbons selected from benzo(e)pyrene, benzo(a)anthracene, chrysen, benzo(b)fluoranthene, benzo(j)fluoranthene, benzo(k)fluoranthene, and dibenzo(a, h)anthracene, wherein the total content of said one or more polyaromatic hydrocarbons is below 10 mg per kg of the one or more process oils according to Standard EN16143:2013, preferably below 5 mg per kg of the one or more process oils, more preferably below 2 mg per kg of the one or more process oils, even more preferably below 1 mg per kg of the one or more process oils. — The one or more process oils contain less than 0.5 mg per kg of benzo(a)pyrene according to Standard EN16143:2013, preferably less than 0.2 mg per kg, more preferably less than 0.1 mg per kg.

One or more of the following features further advantageously defines the silica of the present LU500856 disclosure: — The silica is amorphous silica and/or fumed silica, preferably amorphous silica. — The silica has a specific surface area ranging between 100 m7/g and 350 m°/g as determined by BET experiments in accordance with ISO 5794-1, preferably between 120 m?/g and 300 m?/g, more preferably between 130 m?/g and 250 m?/g, even more preferably between 140 m?/g and 180 m?%/g. — The silica has a particle size distribution ranging between 200 um and 300 um as determined in accordance with ISO 787-18, preferably between 220 um and 280 um.

According to a second aspect, the present disclosure provides a process for making a masterbatch as defined in accordance with the first aspect, remarkable in that said process comprises the step of mixing silica and one or more process oils under mixing conditions, wherein the weight ratio between the one or more process oils and silica is ranging between 2/3 and 1.5, and wherein the one or more process oils are or comprise at least one oil selected from treated distillate aromatic extract, treated residual aromatic extracts and/or mild extracted solvate.

Advantageously, the weight ratio between the one or more process oils and silica is ranging between 0.80 and 1.25, or the weight ratio is 1.

For example, one or more of the following features further defines the mixing conditions of the step of mixing silica and the one or more process oil: — The mixing conditions comprise a pressure equivalent to the atmospheric pressure, namely about 1 atm (101325 Pa). — The mixing conditions comprise a temperature ranging between 15°C and 70°C, preferably between 20°C and 60°C, more preferably between 25°C and 40°C.

According to a third aspect, the present disclosure provides a process for making a rubber formulation, said process comprising the steps of a) providing at least rubber and a masterbatch comprising silica and one or more process oils; b) mixing said at least rubber and a masterbatch comprising silica and one or more process oils together under formulation conditions, said process being remarkable in that said masterbatch comprising silica and one or more process oils is the masterbatch as defined in accordance with the first aspect or as made by the process as defined in accordance with the second aspect.

For example, one or more of the following features further defines the formulation conditions LU500856 of step (b): — The formulation conditions comprise a pressure equivalent to the atmospheric pressure, namely about 1 atm (101325 Pa). — The formulation conditions comprise a temperature ranging between 80°C and 160°C, preferably between 90°C and 150°C, more preferably between 100°C and 140°C. — The formulation conditions comprise a rotor speed ranging between 40 rpm and 60 rpm, preferably between 45 rpm and 55 rpm. — The formulation conditions comprise a load factor ranging between 65% and 75%, preferably between 67% and 73%.

According to a fourth aspect, the present disclosure provides the use of a masterbatch comprising silica and one or more process oils in a process for making a rubber formulation, wherein said masterbatch is defined in accordance with the first aspect or is made by the process as defined in accordance with the second aspect.

According to a fifth aspect, the present disclosure provides a rubber formulation, comprising rubber and a masterbatch comprising silica and one or more process oils, remarkable in that said masterbatch is defined in accordance with the first aspect or is made by the process as defined in accordance with the second aspect.

With preference, whatever the third, the fourth aspect or the fifth aspect, said rubber is or comprises one or more selected of styrene-butadiene rubber, neodymium polybutadiene rubber, polybutadiene rubber, polyisoprene rubber, styrene-isoprene rubber and styrene- isoprene-butadiene rubber. Advantageously, said rubber is styrene-butadiene rubber.

Whatever the third, the fourth aspect or the fifth aspect said masterbatch comprising silica and one or more process oils is advantageously present in an amount of at least 50 phr, preferably of at least 55 phr or at least 60 phr.

Whatever the third, the fourth aspect or the fifth aspect said rubber formulation is advantageously used in the tire manufacturing process.

Description of the figures

Figure 1: SEM picture of the masterbatch of the present disclosure, comprising 50 wt.% of amorphous silica and 50 wt.% of process oil.

Figure 2: SEM picture of the amorphous silica alone (without process oil).

Figure 3: Graph of the dependence of the storage modulus (G’) on strain.

Figure 4: Picture of a piece of rubber compound made with a standard rubber formulation. LU500856

Figure 5: Picture of a piece of rubber compound made with a rubber formulation comprising the masterbatch of the present disclosure.

Detailed description of the disclosure

The following definitions are given:

The terms "comprising", "comprises" and "comprised of" as used herein are synonymous with "including", "includes" or "containing", "contains", and are inclusive or open-ended and do not exclude additional, non-recited members, elements or method steps. The terms "comprising", "comprises" and "comprised of" also include the term “consisting of”.

The recitation of numerical ranges by endpoints includes all integer numbers and, where appropriate, fractions subsumed within that range (e.g. 1 to 5 can include 1, 2, 3, 4, 5 when referring to, for example, a number of elements, and can also include 1.5, 2, 2.75 and 3.80, when referring to, for example, measurements). The recitation of endpoints also includes the recited endpoint values themselves (e.g. from 1.0 to 5.0 includes both 1.0 and 5.0). Any numerical range recited herein is intended to include all sub-ranges subsumed therein.

The particular features, structures, characteristics or embodiments may be combined in any suitable manner, as would be apparent to a person skilled in the art from this disclosure, in one or more embodiments.

The present disclosure provides a masterbatch comprising silica and one or more process oils, wherein the one or more process oils comprise one or more aromatic hydrocarbons that include one or more polyaromatic hydrocarbons, wherein at least one of the polyaromatic hydrocarbons is benzo(a)pyrene, the masterbatch being remarkable in that the one or more process oils contain less than 1 mg per kg of benzo(a)pyrene according to Standard

EN16143:2013; and in that the content of the one or more process oils is ranging between 20 wt.% and 80 wt.% of the total weight of said masterbatch, the remaining part being silica.

The present disclosure also provides a process for making such a masterbatch as defined above, remarkable in that said process comprises the step of mixing silica and at least one process oil under mixing conditions, wherein the weight ratio between said at least one process oil and silica is ranging between 2/3 and 1.5, and wherein said at least one process oil is at least one oil selected from treated distillate aromatic extract, treated residual aromatic extracts and/or mild extracted solvate. With preference, the weight ratio between said at least one process oil and silica is ranging between 0.80 and 1.25, or said weight ratio is 1.

In other words, the masterbatch of the present disclosure consists in silica and said one or LU500856 more process oils, with the content of said one or more process oils ranging between 20 wt.% and 80 wt.% of the total weight of said masterbatch. That means that the masterbatch of the present disclosure is composed of only two components, namely silica and one or more process oils.

Advantageously, the content of the one or more process oils in the masterbatch is ranging between 30 wt.% and 70 wt.%, more preferably between 40 wt.% and 60 wt.%; even more preferably between 45 wt.% and 55 wt. %. For example, the content of said one or more process oils is 50 wt.% of the total weight of said masterbatch and the content of said silica is wt.% of the total weight of said masterbatch.

As no rubber is present in the masterbatch, the silica is only dispersed in the one or more process oils, which itself, when used for preparing rubber formulation, will enhance the dispersibility of the silica into the rubber. The presence of the sole silica and one or more process oils also prevents the incorporation of additional components in the rubber formulation that are usually used to increase the compatibility between the silica and the rubber. Such additional components are typically one or more hydrophobating agents, such as silane. Other additional components that are avoided in the rubber formulation prepared from the masterbatch of the present disclosure are fatty acids, which are usually used to improve mechanical properties such as tensile modulus, hardness, tensile strength and tear strength.

The principle of the masterbatch according to the present disclosure is to inject one or more process oils (i.e. one or more rubber process oils) and some of the silica together as a masterbatch. As the oil content in the rubber compound is always less than the silica, it is indeed impossible to replace the entire volume of the silica in the rubber compound with a masterbatch. The masterbatch is then used to replace all the process oil and a part of the silica in the rubber compound formulation. When the masterbatch is not used, and as the process oil and silica are dosed sequentially, the separate dosing of oil takes time and the separate dosing of silica also takes time. The masterbatch of the present disclosure allows to reduce the whole time for making the rubber formulation, since the dosing of oil is not required anymore.

In addition, the part of the silica that is in the masterbatch is much better dispersed during mixing and this reduces the mixing time and energy consumption.

Also, during the oil dosing, the pipeline needs to be heated, since the oil has a high viscosity.

This is avoided by the use of the masterbatch according to the disclosure, since the masterbatch is a free-flowing substance (dry) and it can be dispensed from a bulk. There is no need for a separate heated container to store the oil, as the masterbatch is a dry mix and can LU500856 be stored in the container like other bulk ingredients.

To make the masterbatch, the mixing conditions advantageously comprise a temperature ranging between 15°C and 70°C, preferably between 20°C and 60°C, more preferably between 25°C and 40°C. The pressure for making the masterbatch corresponds to the atmospheric pressure. For example, to make the masterbatch, the silica and the one or more process oil are directly mixed at room temperature (between 20°C and 25°C) under atmospheric pressure (1 atm). The temperature can be raised during the mixing process for increasing the density of the mixture.

With preference, the masterbatch is a powder and/or has a tapped density ranging between 0.280 g/cm® and 0.725 g/cm® as determined in accordance with ISO787-11, preferably between 0.300 g/cm* and 0.700 g/cm®, more preferably between 0.350 g/cm® and 0.450 g/cm®.

For example, the one or more process oils are at least one oil selected from treated distillate aromatic extract, treated residual aromatic extracts and/or mild extracted solvate. Such process oils are safe process oils for tires with low environmental impact, since they reduce the emissions of polycyclic aromatic hydrocarbons by more than 98%. Advantageously, the one or more aromatic hydrocarbons are in an amount ranging between 55 wt.% and 75 wt.% based on the total weight of said one or more process oils according to ASTM D2007, preferably ranging between 60 wt.% and 73 wt.%. The one or more process oils used in the present disclosure have a composition in accordance with the Regulation (EC) No 1907/2006 of the European Parliament and the Council and present therefore low carcinogenic risk. It is thus highlighted that the process oils used in the present disclosure have a low content of potentially carcinogenic compounds. For example, the amount of benzo(a)pyrene is below 0.5 mg per kg of said one or more process oils according to Standard EN16143:2013, preferably below 0.2 mg per kg of said one or more process oils, more preferably below 0.1 mg per kg of said one or more process oils. Also, advantageously, the one or more polyaromatic hydrocarbons comprise, in addition to benzo(a)pyrene, one or more additional polyaromatic hydrocarbons selected from benzo(e)pyrene, benzo(a)anthracene, chrysen, benzo(b)fluoranthene, benzo(j)fluoranthene, benzo(k)fluoranthene, and dibenzo(a, h)anthracene, wherein the total content of said one or more polyaromatic hydrocarbons is below 10 mg per kg of said one or more process oils according to Standard EN16143:2013, preferably below 5 mg per kg of said one or more process oils, more preferably below 2 mg per kg of said one or more process oils, even more preferably below 1 mg per kg of said one or more process oils.

Advantageously, the one or more process oils further comprise polar compounds in an amount LU500856 ranging between 3 wt.% and below or equal to 10 wt.% based on the total weight of said one or more process oils according to ASTM D2007, preferably comprised between at least 3 wt.% and below or equal to 7 wt.%. For example, the polar compounds have an acid number of at most 0.05 mg KOH/g as determined according to ASTM D664, preferably of at most 0.01 mg

KOH/g. For example, the polar compounds comprise sulfur, nitrogen and/or oxygen.

Advantageously, the one or more process oils further comprise saturated hydrocarbons in an amount ranging between 20 wt.% and 35 wt.% based on the total weight of said one or more process oils according to ASTM D2007, preferably ranging between 25 wt.% and 30. wt.%.

For example, said saturated hydrocarbons comprise paraffinic and/or naphthenic hydrocarbons.

Advantageously, the one or more process oils have a density ranging between 0.940 g/ml and 0.975 g/ml as determined by ASTM D4052, preferably between 0.945 g/ml and 0.970 g/ml, more preferably between 0.950 g/ml and 0.965 g/ml.

Advantageously, the silica which is mixed with the one or more process oils to make the masterbatch is amorphous silica or fumed silica, preferably amorphous silica. For example, the silica has a specific surface area ranging between 100 m?/g and 350 m?%/g as determined by BET experiments, preferably between 120 m?/g and 300 m?/g, more preferably between 130 m°/g and 250 m?/g, even more preferably between 140 m?/g and 180 m°/g. For example, the silica has a particle size distribution ranging between 200 um and 300 um as determined by in accordance with ISO 787-18, preferably between 220 um and 280 um.

The present disclosure also provides a process for making a rubber formulation, said process comprising the steps of a) providing at least rubber and a masterbatch comprising silica and one or more process oils; b) mixing said at least rubber and a masterbatch comprising silica and one or more process oils together under formulation conditions, said process being remarkable in that said masterbatch comprising silica and one or more process oils is the masterbatch as defined above or as made by the process as defined above.

With preference, said masterbatch is present in an amount of at least 50 phr, preferably of at least 55 phr or at least 60 phr. Other formulation conditions comprise a pressure equivalent to the atmospheric pressure, namely about 1 atm (101325 Pa), and/or a temperature ranging between 80°C and 160°C, preferably between 90°C and 150°C, more preferably between 100°C and 140°C. The rotor speed can range between 40 rpm and 60 rpm, preferably between

45 rpm and 55 rpm; and/or the load factor can range between 65% and 75%, preferably LU500856 between 67% and 73%.

For example, said rubber is or comprises one or more selected of styrene-butadiene rubber, neodymium polybutadiene rubber, polybutadiene rubber, polyisoprene rubber, styrene- isoprene rubber and styrene-isoprene-butadiene rubber. Advantageously, said rubber is styrene-butadiene rubber.

Finally, the use of a masterbatch comprising silica and one or more process oils in a process for making a rubber formulation, wherein said masterbatch comprising silica and one or more process oils is the masterbatch as defined above or as made by the process as defined above.

The rubber formulation can be used in tire manufacturing process.

Test and determination methods

Scanning electron microscopy

A JEOL JSM-IT300LV scanning electron microscope has been used. Samples were fixed on the target using double-sided graphite adhesive tape and placed in the instrument. The images were recorded at a residual pressure of 1e-5 atm (about 1e-6 MPa) in the electron beam scanning mode.

Mooney viscosity

Mooney viscosity means the viscosity measurement of rubbers. The Mooney viscosity is reported as ML(1+4) at a specified temperature, where “4” designates the time in minutes and the temperature is 100°C. The measurement is made by embedding a large rotor disc between two plates of rubber which are secured within a heated mold. The rubber is thus held stationary and the rotor is rotated while the resulting torque is graphed in arbitrary Mooney units. The torque is relatively high during the first minute and then decreases as the temperature of the rubber is elevated and the latter becomes more fluid. After four minutes, the motor driving the rotor is turned off and the rubber slowly returns to the resting position, that is, it untwists while the torque decays. The time in seconds that is necessary for it to achieve an 80 percent return is known as the Tso Or relaxation time.

Mooney viscometers MV2000 (Alpha Technologies) are usually supplied with two standard rotors differing only in diameter. They are fabricated from the same non-deforming tool steel as the dies are. The large rotor is 38.10£0.03 mm in diameter and 5.541 0-03 mm thick as measured from the widest points, with the serrations on the surface of the rotor conforming to those of the dies and die holders. The small rotor has a diameter of 30.48+0.03 mm. ML(1+4) LU500856 designates the viscosity measurements on the large rotor while MS +4) designates the viscosity measurements on the small rotor. The analysis on the large rotor were excluded, since at the first stage, it does not determine the exact value due to the high viscosity of the mixture and the results are then not informative. The results obtained with the small rotor were more indicative.

Viscoelastic properties

Viscoelastic properties, such as storage modulus (G’), loss modulus and tan 5, were determined by using a RPA 2000 device from Alpha Technologies. The temperature of the

RPA 2000 device has been set at 100°C, its frequency at 0.1 Hz and its strain sweep is ranging between 1% and 300%. The storage modulus (G’) (solid-like) measures the stored energy and represents therefore the elastic portion. The loss modulus (liquid-like) measures the dissipated energy and represents therefore the viscous portion. The ratio of the loss modulus to storage modulus (G’) in a viscoelastic material is defined as the tan 5, which provides a measure of damping in the material. Tan 6 was determined at 10% of deformation.

Quality of mixing the rubber formulation with silica

The quality of mixing of the rubber formulation with the silica was determined by using a RPA 2000 device from Alpha Technologies, thanks to the program “Process Pein G’ 1-450%” of the

RPA device. G19, was determined and it was given in kPa. A (G14 - G’100%) was also determined and it was given in kPa.

Extrudability

The evaluation of extrudability was performed in a laboratory extruder from Brabender. The screw rotation speed has been set at 30 rpm, the temperature of the rolls on rollers has been set at 50°C, the temperature of the extruder barrel has been set at 90°C and the temperature of the garvey heads has been set at 110°C.

Examples

The embodiments of the present disclosure will be better understood by looking at the example below.

Composition of the masterbatch

Silica used in the masterbatch is silica from Solvay (Zeosil® 1165MP).

The process oil used in the masterbatch is a rubber process oil from Orgkhim (TDAE Norman LU500856 346).

The masterbatch that has been assessed is a masterbatch comprising 50 wt.% of amorphous silica and 50 wt.% of process oil. The amount of benzo(a)pyrene in the process oil has been determined to be equal to 0.1 mg per kg of the process oil according to Standard

EN16143:2013.

Figure 1 is a SEM picture of the masterbatch of the present disclosure comprising 50 wt.% of amorphous silica Zeosil® 1165MP and 50 wt.% of process oil (Norman oil), while figure 2 is a

SEM picture of the amorphous silica Zeosil® 1165MP alone.

To assess the effect of using the masterbatch of the present disclosure, comparative tests were carried out in the formulation of rubber compound for a summer tire tread. Table 1 gives the components and their amounts of the two rubber formulations. Both formulations are based on a solution of styrene-butadiene rubber (SSBR) and of neodymium polybutadiene rubber (BR-Nd) (85 wt./15 wt.).

Table 1: Composition of two rubber formulations

Compounds Rubber formulation 1 | Rubber formulation 2 (phr) (phr) (Not according to the (In accordance with disclosure) the present disclosure)

BR-Nd

Carbon black N121 14.45 14.45

Accelerator 1 (SBC; 1.7 1.7 styrene butadiene copolymer)

Accelerator 2 (DPG; 1.16 1.16 dipropylene glycol)

Antioxidant (TMQ; 2.0 2.0 2,2 4-trimethyl-1,2- dihydroquinoline) * This is the part of silica that cannot be incorporated in the masterbatch, since in a rubber formulation, there are more silica than process oils.

The mixing of the components indicated in Table 1 was carried out in a rubber mixer of the type Intermix, having a chamber volume of 1.7 litres. Three stages of mixing were achieved for increasing the dispersion of the components and as shown respectively in tables 2, 3 and 4, the quality of the dispersion was assessed at each stage by conducting viscosity measurement and shear calculation of the rubber compound.

As shown by determining the Mooney viscosity (see table 2), a decrease in the viscosity of the rubber compound made with formulation 2 which comprises the masterbatch of the present disclosure shows a better distribution of ingredients in the mixing process.

Table 2: Mooney viscosity of rubber compounds in the tread compound

Rubber compound | Rubber compound

Parameters made with rubber made with rubber formulation 1 formulation 2 (In accordance with LU500856 the present disclosure)

First stage of | MS(i+4), units 119.4 87.2 mixing Mooney

A, units Mooney / 2029 1157 sec

Second MS(1+4), units 93.1 63.8 stage of | Mooney mixing

A, units Mooney / 1463 770 sec

Third stage | MS1+4), units 55.6 51.1 of mixing Mooney

A, units Mooney / 670 528 sec

MS 1+4 is the viscosity measured on the small rotor

A - viscosity change per second

Table 3 indicates the energy consumption for the mixing itself measured at the three stages of mixing as well as the unloading temperatures of the rubber compound. The unloading temperature is the temperature that the rubber compound has at the end of each mixing stage.

Table 3: Energy consumption and unloading temperature of rubber compounds in the tread compound at the different stages of mixing

Rubber compound | Rubber compound

Parameters made with rubber made with rubber formulation 1 formulation 2 (In accordance with the present disclosure)

First stage | Energy consumption 0.67 0.62 of mixing (KW/h)

Unloading temperature 150 150 (°C)

Second Energy consumption 0.51 0.40 stage of | (kW/h) mixing

Unloading temperature 155 154 (°C)

Third Energy consumption 0.25 0.20 stage of | (kW/h) mixing

Unloading temperature 110 107 (°C)

By using the masterbatch of the present disclosure, it has been demonstrated that the energy consumption, in particular the electricity consumption, has been decreased at the three stages of mixing. This shows the effectiveness of using the masterbatch in rubber formulation to manufacture rubber compounds.

Evaluation of the quality of the distribution of silica in the rubber compound was determined using a Rubber Process Analyzer (RPA) device. Table 4 gives a comparison between the rubber compound made with formulation 1 and the rubber compound made with formulation 2

Table 4: Viscoelastic properties of the rubber compounds made with a standard rubber formulation and a rubber formulation according to the present disclosure

Rubber compound Rubber compound

Parameters made with rubber made with rubber formulation 1 formulation 2 (In accordance with the present disclosure)

Storage modulus (G’1%) (in 288 260 kPa)

Payne effect (A (G'1% - G'so%)) 136 129 (in kPa)

Measurements were taken with a RBA 2000 at 100°C, at a frequency of 0.1 Hz with a strain sweep ranging between 1% and 300%.

A decrease in G'4, and in Payne effect, demonstrates a significant improvement in the distribution of silica. Indeed, the Payne effect is a dependence of the viscoelastic storage modulus on the amplitude of the applied strain (see figure 3). Above 0.1% strain amplitude, the storage modulus decreases rapidly with increasing amplitude. At 20% strain amplitude, the storage modulus approaches a lower bound. In that region where the storage modulus decreases, the loss modulus shows a maximum. The Payne effect can be attributed to the deformation-induced changes in the material’s microstructure.

Using the RPA device, it was also possible to assess the quality of mixing the rubber formulation with silica. Table 5 indicates such assessment.

Table 5: Assessment of the quality of mixing of the rubber formulation with silica in the rubber compounds in the tread compound at the different stages of mixing

Rubber compound | Rubber compound

Parameters made with rubber made with rubber formulation 1 formulation 2 (In accordance with the present disclosure) of mixing

A (G'1% - G’100%) 604 590 stage of mixing A (G'1% - G100%) 364 255 stage of mixing A (G'1% - G100%) 202 185

A decrease in G’19, A (G’1% - G’100%) indicates improved distribution of the filler in the polymer LU500856 matrix.

The vulcanization properties of the rubber formulation have also been tested. The results of these tests carried out at 155°C are provided in table 6.

Table 6: Vulcanization properties at 155°C of the rubber compounds made with a standard rubber formulation and a rubber formulation according to the present disclosure

Rubber compound | Rubber compound

Parameters made with rubber | made with rubber formulation 1 formulation 2 (In accordance with the present disclosure) rate coefficient of vulcanization sec” 2.1 2.6 (Rv)

Table 6 shows that there is not a significant difference in the vulcanization properties when using a rubber formulation with or without the masterbatch according to the present disclosure.

This means that there is no need to adjust the vulcanization group, such as vulcanization accelerators, vulcanization activators and sulfur.

The physical and mechanical properties of the rubber compounds were studied (see table 7):

Table 7: Physical and mechanical properties of the rubber compounds made LU500856 with a standard rubber formulation and a rubber formulation according to the present disclosure

Rubber Rubber

Parameters (determined compound compound at 155°C, unless stated made with made with otherwise) rubber rubber

Method of formulation 1 formulation 2 determinaton (In accordance with the present disclosure)

ASTM D412 repeated tension test at | GOST Standard cycles 93000 251000 100% deformation 261-79 crack growth resistance GOST Standard cycles 300 480 9983-74 elongation at break (at ASTM D412 % 310 348 100°C)

It was thus evidenced that the rubber compound made with the rubber formulation of the present disclosure shows a decrease in abrasion (from 154 to 140), which is useful for forming the tread.

The repeated tension test at 100% deformation of the rubber compound made with the LU500856 formulation of the present disclosure was also increased, going from 93 000 cycles to 251 000 cycles.

Table 8 presents the elastic-hysteresis properties of the rubber compound made with a standard rubber formulation and a rubber formulation comprising the masterbatch of the present disclosure, as measured on a DMA (Dynamic Mechanical Analyzer).

Table 8: Elastic-hysteresis properties of the rubber compounds made with a standard rubber formulation and a rubber formulation according to the present disclosure

Rubber compound Rubber compound

Parameters made with rubber made with rubber formulation 1 formulation 2 (In accordance with the present disclosure) tan 8 at 0°C 0.403 0.407 tan 8 at 60°C 0.198 0.178

The tan & obtained by dynamic mechanical analysis at 60°C is an indication of the rolling resistance of the rubber compound. The drop of 0.020 between the rubber compound made with a stander rubber formulation and the rubber compound made with the rubber formulation in accordance with the present disclosure is an indication that the rubber compound made with the rubber formulation in accordance with the present discloser has a rolling resistance that is 10.1% less important.

Table 9 evaluates the quality of the extrudate of the rubber compounds made with a standard rubber formulation and a rubber formulation according to the present disclosure. The quality of the extrudate is determined in accordance with ASTM D2230-02.

Table 9: Evaluation of the quality of extrudate of the rubber compounds

Rubber compound Rubber compound

Parameters made with rubber made with rubber formulation 1 formulation 2 (In accordance with the present disclosure)

Scale A 3-2-3-2 3-3-3-2

These data are visually determined by the scale that is used in the determination method

ASTM D 2230-02. This is a method for determining the quality of the workpiece, and therefore the mixing quality of the rubber compound from which the workpiece is made. The tests are carried out on a Garvey die extruder. A workpiece of the same size is produced and the surface smoothness of the workpiece is visually compared. This method has a scale in which a score is assigned based on visual signs. Figures 4 and 5 are pictures of a piece of rubber compounds respectively manufactured with a standard rubber formulation and the rubber formulation comprising the masterbatch according to the present disclosure. The pictures on figure 5 shows that the masterbatch blank has a smooth surface, which means that the process of mixing and dispersing the ingredients was more efficient.

The shrinkage in length after 1 hour was also determined. For the rubber compound with a standard rubber formulation (formulation 1), the shrinkage amounts to 1.4%. For the rubber compound made with the rubber formulation in accordance with the present disclosure (formulation 2), the shrinkage amounts to 0.5%.

All these aspects have rendered the dispersion of the ingredients more effective when using the masterbatch of the present disclosure. It has improved the injection of the rubber and has significantly improved the process of tire production.

Claims (15)

Claims LU500856

1. Masterbatch comprising silica and one or more process oils, wherein the one or more process oils comprise one or more aromatic hydrocarbons that include one or more polyaromatic hydrocarbons, wherein at least one of the polyaromatic hydrocarbons is benzo(a)pyrene, the masterbatch being characterized in that — the one or more process oils contain less than 1 mg per kg of benzo(a)pyrene according to Standard EN16143:2013; and — the content of the one or more process oils is ranging between 20 wt.% and 80 wt.% of the total weight of said masterbatch, the remaining part being silica.

2. Masterbatch according to claim 1, characterized in that the one or more process oils further comprise polar compounds in an amount ranging between 3 wt.% and 10 wt.% based on the total weight of the one or more process oils according to ASTM D2007; with preference, the polar compounds have an acid number of at most 0.05 mg KOH/g as determined according to ASTM D664.

3. Masterbatch according to claim 1 or 2, characterized in that the one or more aromatic hydrocarbons are in an amount ranging between 60 wt.% and 73 wt.% based on the total weight of said one or more process oils according to ASTM D2007; and/or in that the one or more process oils contain less than 0.2 mg per kg of benzo(a)pyrene according to Standard EN16143:2013.

4. Masterbatch according to any one of claim 1 to 3, characterized in that the one or more polyaromatic hydrocarbons further comprise one or more additional polyaromatic hydrocarbons selected from benzo(e)pyrene, benzo(a)anthracene, chrysen, benzo(b)fluoranthene, benzo(j)fluoranthene, benzo(k)fluoranthene, and dibenzo(a, h)anthracene, wherein the total content of said one or more polyaromatic hydrocarbons is below 10 mg per kg of the one or more process oils according to Standard EN16143:2013.

5. Masterbatch according to any one of claims 1 to 4, characterized in that the one or more process oils further comprise saturated hydrocarbons in an amount ranging between 20 wt.% and 35 wt.% based on the total weight of said one or more process oils according to ASTM D2007; with preference, said saturated hydrocarbons comprise paraffinic and/or naphthenic hydrocarbons.

6. Masterbatch according to any one of claims 1 to 5, characterized in that the one or LU500856 more process oils have a density ranging between 0.940 g/ml and 0.975 g/ml as determined by ASTM D4052.

7. Masterbatch according to any one of claims 1 to 6, characterized in that the silica is amorphous silica and/or fumed silica, preferably amorphous silica.

8. Masterbatch according to any one of claims 1 to 7, characterized in that the silica has a specific surface area ranging between 100 m?g and 350 m°/g as determined by BET experiments in accordance with ISO 5794-1.

9. Masterbatch according to any one of claims 1 to 8, characterized in that the silica has a particle size distribution ranging between 200 um and 300 um in accordance with ISO 787-

18.

10. Masterbatch according to any one of claims 1 to 9, characterized in that the masterbatch has a tapped density ranging between 0.280 g/cm® and 0.725 g/cm® as determined in accordance with ISO787-11.

11. A process for making a masterbatch as defined in any one of claims 1 to 10, characterized in that said process comprises the step of mixing silica and one or more process oils under mixing conditions, wherein the weight ratio between the one or more process oils and silica is ranging between 2/3 and 1.5, and wherein the one or more process oils comprise at least one oil selected from treated distillate aromatic extract, treated residual aromatic extracts and/or mild extracted solvate.

12. The process according to claim 11, characterized in that the mixing conditions comprise a temperature ranging between 15°C and 70°C.

13. A process for making a rubber formulation, said process comprising the steps of a) providing at least rubber and a masterbatch comprising silica and one or more process oils; b) mixing said at least rubber and a masterbatch comprising silica and one or more process oils together under formulation conditions, said process being characterized in that said masterbatch comprising silica and one or more process oils is the masterbatch as defined in any one of claims 1 to 10 or as made by the process of claim 11 or 12.

14. The process of claim 13, characterized in that said masterbatch comprising silica and LU500856 one or more process oils is present in an amount of at least 50 phr and/or in that the formulation conditions comprise a temperature ranging between 80°C and 160°C.

15. The process of claim 13 or 14, characterized in that said rubber comprises one or more selected of styrene-butadiene rubber, neodymium polybutadiene rubber, polybutadiene rubber, polyisoprene rubber, styrene-isoprene rubber and styrene-isoprene-butadiene rubber.