REINFORCED ELASTOMER COMPOSITION

Abstract

A curable elastomer composition includes a crosslinkable polymer, and a filler selected from surface-reacted calcium carbonate, precipitated hydromagnesite, or a mixture thereof, wherein the surface-reacted calcium carbonate is a reaction product of natural ground calcium carbonate or precipitated calcium carbonate with carbon dioxide and one or more H.sub.3O.sup.+ ion donors, wherein the carbon dioxide is formed in situ by the H.sub.3O.sup.+ ion donors treatment and/or is supplied from an external source. Furthermore, the disclosure relates to a cured elastomer product formed from said composition, an article including the cured elastomer product, a method of producing a cured elastomer product, and use of the filler for reinforcing a cured elastomer product.

Claims

1. A curable elastomer composition comprising a crosslinkable polymer, and a filler selected from surface-reacted calcium carbonate, precipitated hydromagnesite, or a mixture thereof, wherein the surface-reacted calcium carbonate is a reaction product of natural ground calcium carbonate or precipitated calcium carbonate with carbon dioxide and one or more H.sub.3O.sup.+ ion donors, wherein the carbon dioxide is formed in situ by the H.sub.3O.sup.+ ion donors treatment and/or is supplied from an external source.

2. The curable elastomer composition of claim 1, wherein the crosslinkable polymer is selected from natural or synthetic rubber.

3. The curable elastomer composition of claim 1, wherein the filler is present in an amount from 1 to 80 wt.-%, based on the total weight of the curable elastomer composition, or the filler is present in an amount from 5 to 175 parts per hundred (phr), based on the total weight of the crosslinkable polymer.

4. The curable elastomer composition of claim 1, wherein the filler has a volume median particle size d.sub.50 from 0.1 to 75 μm, and/or a volume top cut particle size d.sub.98 from 0.2 to 150 μm, and/or a specific surface area of from 15 m.sup.2/g to 200 m.sup.2/g, measured using nitrogen and the BET method.

5. The curable elastomer composition of claim 1, wherein the natural ground calcium carbonate is selected from the group consisting of marble, chalk, limestone, and mixtures thereof, or the precipitated calcium carbonate is selected from the group consisting of precipitated calcium carbonates having an aragonitic, vateritic or calcitic crystal form, and mixtures thereof, and/or the at least one H.sub.3O.sup.+ ion donor is selected from the group consisting of hydrochloric acid, sulphuric acid, sulphurous acid, phosphoric acid, citric acid, oxalic acid, an acidic salt, acetic acid, formic acid, and mixtures thereof, preferably the at least one H.sub.3O.sup.+ ion donor is selected from the group consisting of hydrochloric acid, sulphuric acid, sulphurous acid, phosphoric acid, oxalic acid, H.sub.2PO.sub.4.sup.−, being at least partially neutralised by a cation selected from Li.sup.+, Na.sup.+ and/or K.sup.+, HPO.sub.4.sup.2−, being at least partially neutralised by a cation selected from Li.sup.+, Na.sup.+, K.sup.+, Mg.sup.2+, and/or Ca.sup.2+, and mixtures thereof.

6. The curable elastomer composition of claim 1, wherein the precipitated hydromagnesite is surface-treated precipitated hydromagnesite, or a mixture of precipitated hydromagnesite and surface-treated precipitated hydromagnesite.

7. The curable elastomer composition of claim 1, wherein the filler comprises at least one surface-treatment layer on at least a part of the surface of the filler, wherein the at least one surface-treatment layer is formed by contacting the filler with at least one surface-treatment composition in an amount from 0.07 to 9 mg/m.sup.2 of the filler surface, and wherein the at least one surface-treatment composition comprises at least one surface-treatment agent selected from the group consisting of mono- or di-substituted succinic anhydride containing compounds, mono- or di-substituted succinic acid containing compounds, mono- or di-substituted succinic acid salts containing compounds, saturated or unsaturated fatty acids, salts of saturated or unsaturated fatty acids, saturated or unsaturated esters of phosphoric acid, salts of saturated or unsaturated phosphoric acid esters, abietic acid, salts of abietic acid, polydialkylsiloxanes, trialkoxysilanes, and mixtures thereof and reaction products thereof, wherein the at least one surface-treatment agent is selected from the group consisting of a) sodium, potassium, calcium, magnesium, lithium, strontium, primary amine, secondary amine, tertiary amine and/or ammonium salts, whereby the amine form; and/or b) a maleic anhydride grafted polybutadiene homopolymer or a maleic anhydride grafted polybutadiene-styrene copolymer and/or an acid and/or salt thereof, the maleic anhydride grafted polybutadiene homopolymer having i) a number average molecular weight M.sub.n measured by gel permeation chromatography from 1,000 to 20,000 g/mol measured according to EN ISO 16014-1:2019, and/or ii) a number of anhydride groups per chain in the range from 2 to 12, and/or iii) an anhydride equivalent weight in the range from 400 to 2 200, and/or iv) an acid number in the range from 10 to 300 meq KOH/g of maleic anhydride grafted polybutadiene homopolymer, measured according to ASTM D974-14, and/or v) a molar amount of 1,2-vinyl groups in the range from 5 to 80 mol-%, based on the total amount of unsaturated carbon moieties in the maleic anhydride grafted polybutadiene homopolymer, and/or an acid and/or salt thereof, and/or c) a trialkoxysilane, and/or d) a phosphoric acid ester blend of one or more phosphoric acid mono-ester and/or salts thereof and/or one or more phosphoric acid di-ester and/or salts thereof, and/or e) at least one saturated aliphatic linear or branched carboxylic acid and/or salts thereof, and/or f) at least one mono-substituted succinic anhydride consisting of succinic anhydride mono-substituted with a group selected from a linear, branched, aliphatic and cyclic group having a total amount of carbon atoms from at least C.sub.2 to C.sub.30 in the substituent and/or salts thereof, and/or g) at least one polydialkylsiloxane, and/or h) mixtures of the materials according to a) to g).

8. The curable elastomer composition of claim 1, wherein the curable elastomer composition comprises a crosslinking agent, and mixtures thereof.

9. The curable elastomer composition of claim 1, wherein the curable elastomer composition further comprises colouring pigment, dyes, wax, lubricant, oxidative- and/or UV-stabilizer, antioxidant, additional filler, processing aid, plasticizer, additional polymer, and mixtures thereof, preferably the additional filler is selected from the group comprising carbon black, silica, ground natural calcium carbonate, precipitated calcium carbonate, nanofiller, graphite, clay, talc, kaolin clay, calcined kaolin, calcined clay, diatomaceous earth, barium sulfate, titanium dioxide, wollastonite, and mixtures thereof.

10. A cured elastomer product formed from the curable elastomer composition according to claim 1.

11. An article comprising the cured elastomer product according to claim 10, wherein the article is selected from the group comprising tubeless articles, membranes, sealings, gloves, pipes, cable, electrical connectors, oil hoses, shoe soles, o-ring seals, shaft seals, gaskets, tubing, valve stem seals, fuel hose, tank seals, diaphragms, flexi liners for pumps, mechanical seals, pipe coupling, valve lines, military flare blinders, electrical connectors, fuel joints, roll covers, firewall seals, clips for jet engines, conveyor belts, and tires.

12. A method of producing a cured elastomer product, comprising the steps of i) providing a crosslinkable polymer, ii) providing a filler selected from surface-reacted calcium carbonate, precipitated hydromagnesite, or a mixture thereof, wherein the surface-reacted calcium carbonate is a reaction product of natural ground calcium carbonate or precipitated calcium carbonate with carbon dioxide and one or more H.sub.3O.sup.+ ion donors, wherein the carbon dioxide is formed in situ by the H.sub.3O.sup.+ ion donors treatment and/or is supplied from an external source, iii) combining the crosslinkable polymer of step i) and the filler of step ii) in one or more steps to form a curable elastomer composition, and iv) curing the curable elastomer composition of step iii).

13. The method of claim 12, wherein the curing step iv) is carried out by adding a crosslinking agent, heat treatment, ultraviolet light radiation, electron-beam radiation and/or nuclear radiation.

14. A method comprising providing a filler for reinforcing a cured elastomer product, wherein the filler is selected from surface-reacted calcium carbonate, precipitated hydromagnesite, or a mixture thereof, and wherein the surface-reacted calcium carbonate is a reaction product of natural ground calcium carbonate or precipitated calcium carbonate with carbon dioxide and one or more H.sub.3O.sup.+ ion donors, wherein the carbon dioxide is formed in situ by the H.sub.3O.sup.+ ion donors treatment and/or is supplied from an external source.

15. The method of claim 14, wherein the tear resistance and/or the elongation at break and/or the tensile strength and/or the tensile modulus of the cured elastomer product is increased compared to a cured elastomer without filler by at least 5%, and/or wherein the tear resistance and/or the elongation at break and/or the tensile strength and/or the tensile modulus of the cured elastomer product is increased compared to a cured elastomer product containing an isovolumic amount of carbon black N550 as filler by at least 5%, wherein the carbon black has a statistical thickness surface area (STSA) of 39±5 m.sup.2/g, measured according to ASTM D 6556-19, the tear resistance is measured according to NF ISO 34-2, and the elongation at break, the tensile strength and the tensile modulus are measured according NF ISO 37.

16. A process for the surface treatment of precipitated hydromagnesite, the process comprising the steps of: I) providing precipitated hydromagnesite, II) providing at least one surface-treatment composition in an amount ranging from 0.07 to 9 mg/m.sup.2 of the precipitated hydromagnesite surface, wherein the at least one surface-treatment composition comprises at least one surface-treatment agent selected from the group consisting of mono- or di-substituted succinic anhydride containing compounds, mono- or di-substituted succinic acid containing compounds, mono- or di-substituted succinic acid salts containing compounds, saturated or unsaturated fatty acids, salts of saturated or unsaturated fatty acids, saturated or unsaturated esters of phosphoric acid, salts of saturated or unsaturated phosphoric acid esters, abietic acid, salts of abietic acid, polydialkylsiloxanes, trialkoxysilanes, and mixtures thereof and reaction products thereof, and III) contacting the precipitated hydromagnesite and the at least one surface-treatment composition in one or more steps at a temperature in the range from 20 to 180°, the at least one surface-treatment agent is selected from the group consisting of a) sodium, potassium, calcium, magnesium, lithium, strontium, primary amine, secondary amine, tertiary amine and/or ammonium salts, whereby the amine salts are linear or cyclic, of mono- or di-substituted succinic acids, whereby one or both acid groups can be in the salt form, and/or b) a maleic anhydride grafted polybutadiene homopolymer or a maleic anhydride grafted polybutadiene-styrene copolymer and/or an acid and/or salt thereof, the maleic anhydride grafted polybutadiene homopolymer having i) a number average molecular weight M.sub.n measured by gel permeation chromatography from 1,000 to 20,000 g/mol, measured according to EN ISO 16014-1:2019, and/or ii) a number of anhydride groups per chain in the range from 2 to 12, and/or iii) an anhydride equivalent weight in the range from 400 to 2,200, and/or iv) an acid number in the range from 10 to 300 meq KOH/g of maleic anhydride grafted polybutadiene homopolymer, measured according to ASTM D974-14, and/or v) a molar amount of 1,2-vinyl groups in the range from 5 to 80 mol-%, based on the total amount of unsaturated carbon moieties in the maleic anhydride grafted polybutadiene homopolymer, and/or an acid and/or salt thereof, and/or c) a trialkoxysilane, and/or d) a phosphoric acid ester blend of one or more phosphoric acid mono-ester and/or salts thereof and/or one or more phosphoric acid di-ester and/or salts thereof, and/or e) at least one saturated aliphatic linear or branched carboxylic acid and/or salts thereof and/or f) at least one mono-substituted succinic anhydride consisting of succinic anhydride mono-substituted with a group selected from a linear, branched, aliphatic and cyclic group having a total amount of carbon atoms from at least C2 to C30 in the substituent and/or salts thereof, and/or g) at least one polydialkylsiloxane, and/or h) mixtures of the materials according to a) to g).

17. The process of claim 16, wherein in step I) the precipitated hydromagnesite is provided in form of an aqueous suspension having a solids content in the range from 5 to 80 wt.-%, based on the total weight of the aqueous suspension, step III) is carried out by adding the at least one surface-treatment composition to the aqueous suspension and mixing the aqueous suspension at a temperature in the range from 20 to 120° C., and the process further comprises the step of: IV) drying the aqueous suspension during or after step III) at a temperature in the range from 40 to 160° C. at ambient or reduced pressure until the moisture content of the obtained surface-treated precipitated hydromagnesite is in the range from 0.001 to 20 wt.-%, based on the total weight of the surface-treated precipitated hydromagnesite.

18. A surface-treated precipitated hydromagnesite obtained by a process according to claim 16.

Description

EXAMPLES

1. Methods

[0485] Molecular Weight

[0486] The number-average molecular weight M.sub.n is measured by gel permeation chromatography, according to ISO 16014-1:2019 and ISO 16014-2/2019.

[0487] Acid Number

[0488] The acid number is measured according to ASTM D974-14.

[0489] Specific Surface Area (BET)

[0490] The specific surface area (in m.sup.2/g) is determined using the BET method (using nitrogen as adsorbing gas), which is well known to the skilled man (ISO 9277:2010). The total surface area (in m.sup.2) of the filler material is then obtained by multiplication of the specific surface area and the mass (in g) of the corresponding sample.

[0491] Iodine Number

[0492] The iodine number is measured according to DIN 53241/1.

[0493] Particle Size

[0494] Volume median particle size d.sub.50 (vol) and volume top cut particle size d.sub.98 (vol) are evaluated using a Malvern Mastersizer 3000 Laser Diffraction System. The d.sub.50 or d.sub.98 value, measured using a Malvern Mastersizer 3000 Laser Diffraction System, indicates a diameter value such that 50% or 98% by volume, respectively, of the particles have a diameter of less than this value. The raw data obtained by the measurement are analysed using the Mie theory, with a particle refractive index of 1.57 and an absorption index of 0.005.

[0495] The weight median particle size d.sub.50 (wt) and weight top cut particle size d.sub.98 (wt) is determined by the sedimentation method, which is an analysis of sedimentation behaviour in a gravimetric field. The measurement is made with a Sedigraph™ 5100 or 5120, Micromeritics Instrument Corporation. The method and the instrument are known to the skilled person and are commonly used to determine grain size of fillers and pigments. The measurement is carried out in an aqueous solution of 0.1 wt.-% Na.sub.4P.sub.2O.sub.7. The samples were dispersed using a high speed stirrer and sonicated.

[0496] The processes and instruments are known to the skilled person and are commonly used to determine the particle size of fillers and pigments.

[0497] Moisture Pick Up Susceptibility

[0498] The moisture pick up susceptibility of a material as referred to herein is determined in mg moisture/g after exposure to an atmosphere of 10% and 85% relative humidity, respectively, for 2.5 hours at a temperature of +23° C. (±2° C.). The measurement was done in a GraviTest 6300 device from Gintronic. For this purpose, the sample is first kept at an atmosphere of 10% relative humidity for 2.5 hours, then the atmosphere is changed to 85% relative humidity at which the sample is kept for another 2.5 hours. The weight increase between 10% and 85% relative humidity is then used to calculate the moisture pick-up in mg moisture/g of sample.

[0499] Analysis on Cured Polymer Product Samples

[0500] For all tests on the cured elastomer product samples, a minimum period of 16 h was kept between molding and testing of the product samples. The samples were kept in a controlled environment (temperature: 23±2° C., relative humidity: 50±5%).

[0501] Tensile Strength, Elongation at Break, Tensile Modulus M300 and M100:

[0502] Tensile strength, elongation at break, tensile modulus M300 and M100 were measured according to NF ISO 37 on a Zwick T2000, Zwick Z005, or Zwick Z100 device using the parameters outlined in Table 1 below.

TABLE-US-00001 TABLE 1 Tensile strength, elongation at break, modulus M300, and Modulus M100 measurement parameters. Standard NF ISO 37 Type of test piece Type H2 Preparation of test piece Samples were cut from sheets of 2 ± 0.2 mm thickness Cutting direction Parallel of calendering direction State Initial Temperature 23 ± 2° C. Relative humidity 50 ± 5% Number of test pieces used 3 Units MPa for strength Test specimen conditioning before test Minimum 16 h at 23° C. and 50% relative humidity Conditioning after ageing in air None Conditioning after immersion None Rate of grip separation 500 mm/min

[0503] Tear Resistance

[0504] Tear resistance (DELFT) was measured according to NF ISO 34-2 on a Zwick T2000, Zwick Z005, Zwick Z100 device using the parameters outlined in Table 2.

TABLE-US-00002 TABLE 2 Tear resistance (DELFT) measurement parameters. Standard NF ISO 34-2 Type of test piece Delft Preparation of test piece Samples were cut from sheets of 2 ± 0.2 mm thickness Cutting direction perpendicular to calendering direction State Initial Temperature 23 ± 2° C. Relative humidity 50 ± 5% Number of test pieces used 3 Test specimen conditioning Minimum 16 h at 23° C. and before test 50% relative humidity Rate of grip separation 500 mm/min

[0505] Hardness Shore A

[0506] Hardness (Shore A) was measured according to NF ISO 7619-1 on a Bareiss Digitest II apparatus using the parameters outlined in Table 3.

TABLE-US-00003 TABLE 3 Hardness (Shore A) measurement parameters. Standard NF ISO 7619-1 Type of device A Type of test piece 50 × 25 × (2.0 ± 0.2) mm Number of test pieces used 3 Test carry out 3 s Preparation of test piece Samples were cut from sheets of 2 ± 0.2 mm thickness State Initial Temperature 23 ± 2° C. Relative humidity 50 ± 5% Number of measurements 5 Unit points Test specimen conditioning before test Minimum 16 h at 23° C. and 50% relative humidity

[0507] Hardness IRHD

[0508] Hardness (IRHD) was measured according to NF ISO 48-1 on a Wallace IRHD H14/1+ Gibitre-PC type N automatic apparatus using the parameters outlined in Table 4.

TABLE-US-00004 TABLE 4 Hardness (IRHD) measurement parameters. Standard NF ISO 48-1 Method N Type of test piece 50 × 20 × (2.0 ± 0.2) mm Number of test pieces used 4 Preparation of test piece Samples were cut from sheets of 2 ± 0.2 mm thickness State Initial Temperature 23 ± 2° C. Relative humidity 50 ± 5% Number of measurements 5 Unit ° Test specimen conditioning Minimum 16 h to 6 days at 23° C. before test and 50% relative humidity Conditioning after immersion none

[0509] Compression Set

[0510] These tests were provided on compression set plots type B, which are cylindrical molded rubber samples. The diameter of the sample was 13.0±0.5 mm and the thickness was 6.3±0.3 mm. Tests were carried out for 72 h at 100° C. using the parameters outlined in Table 5.

TABLE-US-00005 TABLE 5 Compression set. Standard NF ISO 815-1 Method After 30 ± 3 min Type of test piece B Number of test pieces used 3 or 4 Unit % Compression 25% Conditioning after immersion none Lubricant Silicone Preparation of test piece molded Temperature 23 ± 2° C. Relative humidity 50 ± 5%

2. Materials

[0511] Treatment A

[0512] Treatment A is a low molecular weight polybutadiene functionalized with maleic anhydride (M.sub.n=3100 Da, Brookfield viscosity: 6500 cps+/−3500 at 25° C., acid number: 40.1-51.5 meq KOH/g, total acid: 7-9 wt.-%, microstructure (molar % of butadiene): 20-35% 1-2 vinyl functional groups), commercially available under the trade name RICON®130MA8 (Cray Valley).

[0513] Treatment B

[0514] Treatment B is (bis[3-(triethoxysilyl)propyl]tetrasulfide) (TESPT) (CAS: 40372-72-3), commercially available from Sigma-Aldrich.

[0515] Treatment C

[0516] Treatment C is a fatty acid mixture consisting of about 40% stearic acid and about 60% palmitic acid.

[0517] Treatment D

[0518] Treatment D is a mono-substituted alkenyl succinic anhydride (2,5-furandione, dihydro-, mono-C.sub.15-20-alkenyl derivates, CAS: 68784-12-3). It is a blend of mainly branched octadecenyl succinic anhydrides (CAS: 28777-98-2) and mainly branched hexadecenyl succinic anhydrides (CAS: 32072-96-1), wherein the blend contains more than 80 wt.-% branched octadecenyl succinic anhydrides, based on the total weight of the blend. The purity of the blend was >95 wt.-%, and the residual olefin content was below 3 wt.-%, based on the total weight of the blend.

[0519] Treatment E

[0520] Treatment E is octadecyltriethoxyilane (CAS: 7399-00-0, commercially available from Gelest Inc.)

[0521] Treatment F

[0522] Treatment F is a low molecular weight, low vinyl butadiene functionalized with maleic anhydride (M.sub.n=5000 g/mol, Brookfield viscosity: 48000 cps at 25° C., 1,2 vinyl content=28 wt.-%; MA groups/chain=5), commercially available under the trade name RICOBOND® 1031 (Cray Valley).

[0523] Powder 1

[0524] Powder 1 is a surface-reacted calcium carbonate with a d.sub.50 (vol) of 4.8 μm, a d.sub.98 (vol) of 13.3 μm, and specific surface area SSA of 33 m.sup.2/g.

[0525] Powder 2

[0526] Powder 2 is a surface-reacted calcium carbonate composed of 80% hydroxyapatite and 20% calcite (BET=85 m.sup.2/g, d.sub.50 (vol)=6.1 μm, d.sub.98 (vol)=13.8 μm), prepared with the following method:

[0527] In a mixing vessel, 350 liters of an aqueous suspension of natural ground calcium carbonate was prepared by adjusting the solids content of a ground marble calcium carbonate from Hustadmarmor, Norway, with a particle size distribution of 90 wt.-% less than 2 μm as determined by sedimentation, such that a solids content of 10 wt.-%, based on the total weight of the aqueous suspension, is obtained.

[0528] Whilst mixing the suspension, 62 kg of a 30% concentrated phosphoric acid was added to said suspension over a period of 10 minutes at a temperature of 70° C. Finally, after the addition of the phosphoric acid, the slurry was stirred for additional 5 minutes, before removing it from the vessel and drying.

[0529] Powder 3

[0530] Powder 3 is a surface-reacted calcium carbonate composed of 83% hydroxyapatite and 17% calcite (BET=67 m.sup.2/g, d.sub.50 (vol)=1.2 μm, d.sub.98 (vol)=9.7 μm).

[0531] Powder 4

[0532] Powder 4 is a precipitated hydromagnesite (BET specific surface area: 84.2 m.sup.2/g, d.sub.50 (vol)=7.6 μm; d.sub.95 (vol)=20.6 μm).

[0533] Powder 5

[0534] Powder 5 has been prepared by surface-treating powder 4 with 2.5 wt.-% of treatment A. To carry the treatment, the treatment agent (25 g) was first dispersed in 100 mL of deionized water, heated to 60° C. and neutralized to pH 9-10 with NaOH solution.

[0535] A suspension of powder 4 (1 kg in 7.5 L deionized water) was prepared in a 10 L ESCO batch reactor (ESCO-Labor AG, Switzerland) and heated to 85° C. The pH was adjusted to 10-11 with Ca(OH).sub.2 and the neutralized treatment agent was then added under vigorous stirring. Mixing was continued at 85° C. for 45 minutes, and the suspension was then transferred to metallic tray and dried in an oven (110° C.). The dried cake was then deagglomerated using a SR300 rotor beater mill (Retsch GmbH, Germany).

[0536] Powder 6

[0537] Powder 6 was prepared by surface treatment of powder 2 with 7.5 wt.-% of treatment B. Surface treatment was carried out in a high speed mixer (Somakon MP-LB Mixer, Somakon Verfahrenstechnik, Germany). Powder 2 (300 g) was put in the mixer and stirred at 500 rpm and room temperature. Treatment B (7.5 wt.-%, 24 g) was then added dropwise to the mixture and stirring was continued for another 10 minutes. After that time, the mixture was allowed to cool and the powder was collected.

[0538] Powder 7

[0539] Powder 7 is a precipitated hydromagnesite (d.sub.50 (vol)=8.8 μm; d.sub.98 (vol)=29 μm).

[0540] Powder 8

[0541] Powder 8 is a precipitated hydromagnesite (d.sub.50 (vol)=11.6 μm; d.sub.98 (vol)=47 μm).

[0542] Powder 9

[0543] Powder 9 was prepared by surface treatment of powder 7 with 4 wt.-% of treatment C. Surface treatment was carried out in a high speed mixer (Somakon MP-LB Mixer, Somakon Verfahrenstechnik, Germany equipped with a 2.5 L vessel). Powder 7 (150 g) was put in the mixer and stirred at 500 rpm and 120° C. Treatment C (4 wt.-%, 6 g) was then added to the mixture and stirring was continued for another 15 minutes. After that time, the mixture was allowed to cool and the powder was collected.

[0544] Powder 10

[0545] Powder 10 was prepared by surface treatment of powder 7 with 10 wt.-% of treatment C. Surface treatment was carried out in a high speed mixer (Somakon MP-LB Mixer, Somakon Verfahrenstechnik, Germany equipped with a 2.5 L vessel). Powder 7 (150 g) was put in the mixer and stirred at 500 rpm and 120° C. Treatment C (10 wt.-%, 15 g) was then added to the mixture and stirring was continued for another 15 minutes. After that time, the mixture was allowed to cool and the powder was collected.

[0546] Powder 11

[0547] Powder 11 was prepared by surface treatment of powder 7 with 4 wt.-% of treatment D. Surface treatment was carried out in a high speed mixer (Somakon MP-LB Mixer, Somakon Verfahrenstechnik, Germany equipped with a 2.5 L vessel). Powder 7 (150 g) was put in the mixer and stirred at 500 rpm and 120° C. Treatment D (4 wt.-%, 6 g) was then added to the mixture and stirring was continued for another 15 minutes. After that time, the mixture was allowed to cool and the powder was collected.

[0548] Powder 12

[0549] Powder 12 was prepared by surface treatment of powder 7 with 10 wt.-% of treatment D. Surface treatment was carried out in a high speed mixer (Somakon MP-LB Mixer, Somakon Verfahrenstechnik, Germany equipped with a 2.5 L vessel). Powder 7 (150 g) was put in the mixer and stirred at 500 rpm and 120° C. Treatment D (10 wt.-%, 15 g) was then added to the mixture and stirring was continued for another 15 minutes. After that time, the mixture was allowed to cool and the powder was collected.

[0550] Powder 13

[0551] Powder 13 was prepared by surface treatment of powder 7 with 5 wt.-% of treatment C and 5 wt.-% of treatment A. Surface treatment was carried out in a high speed mixer (Somakon MP-LB Mixer, Somakon Verfahrenstechnik, Germany equipped with a 2.5 L vessel). Powder 7 (150 g) was put in the mixer and stirred at 500 rpm and 120° C. Treatment C (5 wt.-%, 7.5 g) was first added slowly and treatment A (5 wt.-%, 7.5 g) was added subsequently to the mixture. Stirring was then continued for another 15 minutes. After that time, the mixture was allowed to cool and the powder was collected.

[0552] Powder 14

[0553] Powder 14 was prepared by surface treatment of powder 8 with 4 wt.-% of treatment D. Surface treatment was carried out in a high speed mixer (Somakon MP-LB Mixer, Somakon Verfahrenstechnik, Germany equipped with a 2.5 L vessel). Powder 8 (150 g) was put in the mixer and stirred at 500 rpm and 120° C. Treatment D (4 wt.-%, 6 g) was then added to the mixture and stirring was continued for another 15 minutes. After that time, the mixture was allowed to cool and the powder was collected.

[0554] Powder 15

[0555] Powder 15 was prepared by surface treatment of powder 8 with 4 wt.-% of treatment B. Surface treatment was carried out in a high speed mixer (Somakon MP-LB Mixer, Somakon Verfahrenstechnik, Germany equipped with a 2.5 L vessel). Powder 8 (150 g) was put in the mixer and stirred at 500 rpm and 120° C. Treatment B (4 wt.-%, 6 g) was then added to the mixture and stirring was continued for another 15 minutes. After that time, the mixture was allowed to cool and the powder was collected.

[0556] Powder 16

[0557] Powder 16 was prepared by surface treatment of powder 8 with 4 wt.-% of treatment E. Surface treatment was carried out in a high speed mixer (Somakon MP-LB Mixer, Somakon Verfahrenstechnik, Germany equipped with a 2.5 L vessel). Powder 8 (150 g) was put in the mixer and stirred at 500 rpm and 120° C. Treatment E (4 wt.-%, 6 g) was then added to the mixture and stirring was continued for another 15 minutes. After that time, the mixture was allowed to cool and the powder was collected.

[0558] Powder 17

[0559] Powder 17 has been prepared by surface-treating powder 7 with 4 wt.-% of treatment C. To carry the treatment, the treatment agent (8 g) was first dispersed in 300 mL of deionized water, heated to 80° C. and neutralized with NaOH solution (1.5 g).

[0560] A suspension of powder 7 (0.2 kg in 5 L deionized water) was prepared in a 10 L ESCO batch reactor (ESCO-Labor AG, Switzerland) and heated to 85° C. The neutralized treatment agent was then added under vigorous stirring. Mixing was continued at 85° C. for 45 minutes, and the suspension was then filtered in filter press, transferred to metallic tray and dried in an oven (110° C.). The dried cake was then deagglomerated using a SR300 rotor beater mill equipped with a 200 micrometers sieve (Retsch GmbH, Germany).

TABLE-US-00006 TABLE 6 Physical characteristics of powders 7 to 17 (n.d.: not determined). Density TGA Mass Moisture (He-pycno- loss pick-up BET metry) 25-105° C. susceptibility Powder (m.sup.2/g) (g/cm.sup.3) (wt .- %) (mg/g) Powder 7 46.7 2.03 3.03 27.2 Powder 8 42.7 2.16 2.89 18.1 Powder 9 39.4 2.01 2.07 23.3 Powder 10 36.5 2.00 2.08 22.4 Powder 11 31.7 2.00 1.79 16.6 Powder 12 32.2 1.92 1.74 12.5 Powder 13 33.4 1.86 2.37 21.8 Powder 14 22.3 2.11 1.81 5.5 Powder 15 26.5 2.17 1.84 7.6 Powder 16 22.4 n.d. 1.82 7.7 Powder 17 42.8 2.06 1.08 30.3

[0561] Powder 18

[0562] Powder 18 is a surface-reacted calcium carbonate (BET=139 m.sup.2/g, d.sub.50 (vol)=6.1 μm, d.sub.98 (vol)=14.2 μm) prepared with the following method:

[0563] In a mixing vessel, 350 liters of an aqueous suspension of natural ground calcium carbonate was prepared by adjusting the solids content of a ground marble calcium carbonate from Hustadmarmor, Norway with a particle size distribution of 90 wt.-% less than 2 μm as determined by sedimentation, such that a solids content of 10 wt.-%, based on the total weight of the aqueous suspension, is obtained.

[0564] Whilst mixing the suspension, 62 kg of a 30% concentrated phosphoric acid was added to said suspension over a period of 10 minutes at a temperature of 70° C. Additionally, during the phosphoric acid addition, 1.9 kg of citric acid was added rapidly (about 30 s) to the slurry. Finally, after the addition of the phosphoric acid, the slurry was stirred for additional 5 minutes, before removing it from the vessel and drying.

[0565] Powder 19

[0566] Powder 19 has been prepared by surface-treating powder 7 with 5 wt.-% of treatment A. To carry out the treatment, the treatment agent (35 g) was first dispersed in 400 mL of deionized water, heated to 60° C. and neutralized to pH 10 with NaOH solution.

[0567] A suspension of powder 7 (700 g in 6 L deionized water) was prepared in a 10 L ESCO batch reactor and heated to 85° C. The pH was adjusted to 10 with Ca(OH).sub.2 and the neutralized treatment agent was then added under vigorous stirring. Mixing was continued at 85° C. for 45 minutes, and the suspension was then filtered on a filter press and dried overnight in an oven (110° C.). The dried filter cake was then deagglomerated using a Retsch SR300 rotor beater mill.

[0568] Powder 20

[0569] Powder 20 is a precipitated hydromagnesite (BET=70.1 m.sup.2/g, d.sub.50 (vol)=6.3 μm; d.sub.98 (vol)=70 μm).

[0570] Powder 21

[0571] Powder 21 was prepared by surface treatment of powder 2 with 8 wt.-% of treatment B. Surface treatment was carried out in a high speed mixer (Somakon MP-LB Mixer, Somakon Verfahrenstechnik, Germany). Powder 2 (500 g) was put in the mixer and stirred at 500 rpm and 70° C. Treatment B (8 wt.-%, 40 g) was then added dropwise to the mixture and stirring was continued for another 15 minutes. After that time, the mixture was allowed to cool and the powder was collected.

[0572] Powder 22

[0573] Powder 22 has been prepared by surface-treating powder 7 with 7.5 wt.-% of treatment A. To carry out the treatment, the treatment agent (64 g) was first dispersed in 400 mL of deionized water, heated to 60° C. and neutralized to pH 10 with NaOH solution.

[0574] A suspension of powder 7 (850 g in 6 L deionized water) was prepared in a 10 L ESCO batch reactor and heated to 85° C. The pH was adjusted to 10 with Ca(OH).sub.2 and the neutralized treatment agent was then added under vigorous stirring. Mixing was continued at 85° C. for 45 minutes, and the suspension was then filtered on a filter press and dried overnight in an oven (110° C.). The dried filter cake was then deagglomerated using a Retsch SR300 rotor beater mill.

[0575] Powder 23

[0576] Powder 23 has been prepared by treating a precipitated hydromagnesite powder with treatment agent B. Surface treatment was carried out in a high speed mixer (Somakon MP-LB Mixer, Somakon Verfahrenstechnik, Germany). The untreated precipitated hydromagnesite powder (400 g) was put in the mixer and stirred at 500 rpm and 70° C. Treatment B (7.5 wt.-%, 30 g) was then added dropwise to the mixture and stirring was continued for another 15 minutes. After that time, the mixture was allowed to cool and the powder was collected (BET=32.8 m.sup.2/g, d.sub.50 (vol)=8.6 μm; d.sub.98 (vol)=μm).

[0577] Powder CE1 (Comparative)

[0578] Powder CE1 is a N550 carbon black filler, commercially available from Orion engineered Carbons GmbH (Purex® HS 45, iodine number: 43±5 mg/g, STSA surface area (according to ASTM D 6556): 39±5 m.sup.2/g).

[0579] Powder CE2 (Comparative)

[0580] Powder CE2 is high purity fully calcined kaolin, commercially available from Imerys (Polestar 200R, d.sub.50 (wt)=2 μm).

[0581] Powder CE3 (Comparative)

[0582] Powder CE3 is a calcium carbonate having a d.sub.50 (wt) of 2.4 μm, a d.sub.98 of 9 μm and a BET specific surface area of about 2 m.sup.2/g.

[0583] Powder CE4 (Comparative)

[0584] Powder CE4 is high purity fully calcined kaolin, commercially available from Imerys (Polestar 200P, d.sub.50 (wt)=2 μm).

[0585] Powder CE5 (Comparative)

[0586] Powder CE5 is a precipitated silica, commercially available from Evonik (Ultrasil VN3, BET specific surface area=180 m.sup.2/g).

[0587] Powder CE6 (Comparative)

[0588] Powder CE6 is a N220 carbon black filler, commercially available from Cabot under the Vulcan® 6, iodine number: 121 mg/kg, STSA surface area (according to ASTM D 6556): 104 m.sup.2/g).

[0589] Powder CE7 (Comparative)

[0590] Powder CE7 is ground calcium carbonate powder from France (Micromya-OM), d.sub.50 (wt)=2.4 μm, d.sub.98 (wt)=20 μm.

3. Examples

3.1. Examples Series A: Simple EPDM Formulations

[0591] Cured elastomer products were prepared as described in the following, wherein the compositions of the prepared cured elastomer products are compiled in Table 8 below.

[0592] Step 1: Internal Mixing

[0593] As a first step, each batch were mixed in a HAAKE internal mixer with 300 cm.sup.3 capacity equipped with Banbury rotors. The temperature was set at 40° C. at the beginning of each mixing, during the process the temperature raised up to 90° C. depending on the filler being incorporated. The following process had been used for each batch (Table 7):

TABLE-US-00007 TABLE 7 Internal mixing procedure. Time (min) Operation Speed (rpm) t = 0 Introduction of elastomer precursor 40 and mineral filler (40° C.) t = 1 Insertion of carbon black and oil 40 t = 5 Dumping of the mixture 40

[0594] Step 2: External Mixing

[0595] For the second step, mixing with the peroxide curing agent was performed on an instrumented cylinder mixer (300×700 or 150×350). All the rubbers were mixed with the same times, cylinder speeds, and cylinder spacing as to not influence in their rheological properties comparison. The cooling system was set to 25° C. and the metal guides were set as to allow the rubber to occupy 70% of the cylinder surface. In between two accelerations the cylinders are cleaned and are let cool. The detail proceedings for this process are described in Table 8 below.

TABLE-US-00008 TABLE 8 External mixing procedure. Cylinder Time (min) Operation Spacing (mm) t = 0 Introduction of the mix from Step 1 1 t = 2 Insertion of the curing system 1 (peroxide and coagent) t = 6 5 thin passings 0.6 Calendering sheet, thickness 2 mm 2

[0596] Step 3: Molding

[0597] The pieces were then molded at 160° C. and 200 bar pressure by compression molding. This way, small 150×150×2 mm sheets were prepared. The curing time, which determines the molding time, was determined through a rheological MDR (Moving Die Rheometer) test.

[0598] The following elastomer compositions of Table 9 were obtained following the method described above. All elastomer compositions had an isovolumic amount of fillers. All fillers were coupled 50/50% with carbon black in volume. Therefore the carbon black reference batch contains 100 phr of N550. The other batches contain 50 phr of N550 and a slightly variable amount of mineral filler in function of their density, in order to have an amount of mineral filler equivalent to the volume of 50 phr of carbon black (indicated in Table 9 with an asterisk).

TABLE-US-00009 TABLE 9 EPDM elastomer compositions (phr: parts per hundred). Example A-E1 A-E2 A-E3 A-E4 A-E5 A-CE1 A-CE2 A-CE3 EPDM Vistalon 2504 (phr) 100  100  100  100  100  100 100  100  Powder 1 (phr)  76* Powder 2 (phr)  77* Powder 3 (phr)  78* Powder 4(phr)  60* Powder 5 (phr)  60* Powder CE1(phr) 50 50 50 50 50 100 50 50 Powder CE2 (phr)  73* Powder CE3 (phr)  75* Torilis 6200 plasticizer (phr) 10 10 10 10 10 10 10 10 Peroxide DC40 crosslinking  7  7  7  7  7 7  7  7 agent (phr) Rhenogran TAC 50%  2  2  2  2  2 2  2  2 crosslinking coagent (phr)

[0599] The obtained cured elastomer compositions had the properties compiled in Table 10 below.

TABLE-US-00010 TABLE 10 Effect on mechanical properties (series A). Hardness M100 Strength at Elongation Tear resistance/ Sample IRDH (°) (MPa) break (MPa) (%) DELFT (MPa) A-E1 73.5 5.09 10.94 225.9 26.73 A-E2 85.2 5.75 10.85 215 32.33 A-E3 77.6 5.137 11.59 225.9 20.22 A-E4 82.3 6.36 13.19 200 32.13 A-E5 82.8 6.09 11.63 200 31.6 A-CE1 80.2 10.66 — 144.75 20 A-CE2 75.7 5.69 — — — A-CE3 79 3.78  7.34 — —

[0600] The effect on elongation at break and on tear resistance (DELFT) is shown in Table 10.

3.2. Examples Series B: EPDM Sulfur-Cured Formulations

[0601] Cured elastomer products were prepared as described in the following, wherein the compositions of the prepared cured elastomer products are compiled in Table 11 below.

Step 1: Internal Mixing

[0602] Internal Mixing was carried out as described in Example 3.1.

Step 2: External Mixing External Mixing was carried out as described in Example 3.1., wherein mixing with the peroxide curing agent was performed on an instrumented cylinder mixer (150×350).

Step 3: Molding

[0603] The pieces were then molded at 160° C. or 180° C. and 100 kgf/cm pressure by compression molding. This way, small 150×150×2 mm sheets were prepared. The curing time, which determines the molding time, was determined through a rheological MDR test.

[0604] The composition of the curable elastomer compositions are shown in Table 11 below and the properties of the cured elastomer compositions are combined in Table 12 below. Amounts of experimental fillers have been adjusted according to the measured density of each filler to correspond to the same volume as 40 phr of Powder CE1 (carbon black).

TABLE-US-00011 TABLE 11 EPDM elastomer compositions (phr: parts per hundred). Example B-E2 B-E4 B-E6 B-CE1 B-CE5 EPDM KELTAN 6950C (phr) 100 100 100 100 100 Powder 2 (phr) 61.5 Powder 4 (phr) 47 Powder 6 (phr) 58 Powder CE1 (phr) 40 40 40 80 40 Powder CE5 (phr) 43 Torilis 6200 plasticizer (phr) 20 20 20 20 20 ZnO vulcanization accelerator 5 5 5 5 5 (phr) Stearic acid (phr) 1 1 1 1 1 Protector octamine (phr) 1 1 1 1 1 CBS 80 vulcanization 2.5 2.5 2.5 2.5 2.5 accellerator (phr) TBzTD 70 vulcanization 1 1 1 1 1 accellerator (phr) Sulfur (phr) 1.5 1.5 1.5 1.5 1.5

TABLE-US-00012 TABLE 12 Effect on mechanical properties (series B). M100 Strength at Elongation Tear resistance/ Sample (MPa) break (MPa) at break (%) DELFT (MPa) B-E2 3.9 12.6 345 — B-E4 3.6 14.6 347 — B-E6 4.8 15 388 37 B-CE1 7.7 17.5 211 38.6 B-CE5 4.6 16.3 324 —

[0605] The effect on elongation at break and the tear resistance (DELFT) is shown in Table 12.

3.3. Examples Series C: EPDM Peroxide-Cured Formulations

[0606] Step 1: Internal Mixing

[0607] As a first step, batches of EPDM and filler were mixed in a 2 L Banbury internal mixer according to the mixing procedure shown in Table 13 below. The temperature was set at 40° C. at the beginning of each mixing, and the temperature raised up to 150° C. during the process, depending on the filler being incorporated.

TABLE-US-00013 TABLE 13 Internal mixing procedure. Time (min:s) Operation Speed (rpm) t = 00:00 Introduction of EPDM 50 t = 00:50 Addition of the filler 50 t = 02:30 Addition of ⅔ of Powder CE1 50 t = 05:30 Addition of ⅓ of Powder CE1 + 50 paraffinic oil t = 06:30 Ramp cleaning 50 t = 08:30 Dropping 50

[0608] Step 2: External Mixing

[0609] For the second step, mixing with the peroxide crosslinking agent was performed on a cylinder mixer (300×700). All the elastomer precursors were mixed with the same times, cylinder speeds, and cylinder spacing. The cooling system was set to 40° C. and the metal guides were set as to allow the elastomer precursor to occupy 70% of the cylinder surface. The detail proceedings for this process are described in Table 14 below.

TABLE-US-00014 TABLE 14 External mixing procedure. Cylinder Time (min:s) Operation Spacing (mm) t = 00:00 Introduction of the mix from Step 1 2.5 t = 01:30 Insertion of the curing system 2.5 (peroxide and coagent) t = 06:00 3 thin passes 0.5 Calendering sheet, thickness 2 mm 2

[0610] Step 3: Molding

[0611] Sheets of the elastomer composition were produced by compression molding at 180° C. and 200 bar pressure. This way, small 300×300×2 mm plates were made. The curing time, which determines the molding time, was determined through a rheological MDR (Moving Die Rheometer) test. The t98 value (time needed to reach 98% of the crosslinking, determined by MDR analysis) was taken as time of curing for the press plates. The fabrication of the compression set test specimens was done with the same procedure, meaning by compression molding. The curing time used was the addition of 10 min to the t98 value as the thickness of these test specimens is higher than the press plates.

[0612] The following elastomer compositions of Table 15 were obtained following the method described above. All elastomer compositions had an isovolumic amount of fillers. All fillers were coupled 50/50% with carbon black in volume. Therefore, the carbon black reference sample C-CE1 contains 100 phr of N550 (powder CE1). The other samples contain 50 phr of N550 and a slightly variable amount of mineral filler in function of their density, in order to have an amount of mineral filler equivalent to the volume of 50 phr of carbon black (indicated in Table 15 with an asterisk).

TABLE-US-00015 TABLE 15 EPDM elastomer compositions (phr: parts per hundred). Example C-CE1 C-E18 C-E19 C-E20 EPDM Vistalon 2504N (phr) 100 100 100 100 Powder CE1 (phr) 100 50 50 50 Powder 18 (phr) 76.4* Powder 19 (phr) 60.8* Powder 20 (phr) 72.2* Torilis 6200 plasticizer (phr) 10 10 10 10 Peroxide DC40 crosslinking 7 7 7 7 agent (phr) Rhenogran TAC 50% crosslinking 2 2 2 2 coagent (phr)
The obtained elastomer compositions had the mechanical properties compiled in Table 16 below.

TABLE-US-00016 TABLE 16 Mechanical properties of the elastomer compositions (series C). Sample Hardness (Shore A) M50 (MPa) Elongation at break (%) C - CE1 79.1 3.7 142 C - E18 84.3 4.7 208 C - E19 83.1 4.4 149 C - E20 82.2 3.7 185
As can be seen from Table 16, the shore A hardness of the inventive cured elastomer products (C-E18, C-E19, and C-E20) is improved. In addition, the inventive cured elastomer products showed good M50 modulus and the elongation at break or even a further improvement of these mechanical properties.

3.4. Examples Series D: Tire Tread Sulfur-Cured SBR Formulations

[0613] Step 1: Internal Mixing

[0614] As a first step, batches of SBR rubber and filler were mixed in a 2 L Banbury internal mixer according to the mixing procedure shown in Table 17 below. The temperature was set at 40° C. at the beginning of each mixing, and the temperature raised up to 150° C. during the process the temperature, depending on the filler being incorporated.

TABLE-US-00017 TABLE 17 Internal mixing procedure. Time (min:s) Operation Speed (rpm) t = 00:00 Introduction of SBR rubber 50 t = 00:30 Addition of the filler + ⅓ powder CE6 50 t = 01:45 Addition of ⅔ of powder CE6 + oil 50 (Torilis 6200 plastcizer) t = 02:45 Addition of the curing system 50 (sulfur and accelerators) t = 04:15 Ramp cleaning adjusted t = 06:30 Dumping of the compound adjusted

[0615] Step 2: External Mixing

[0616] For the second step, mixing with the curing system was performed on an external mixer Agila (300×400). All the elastomer precursors were mixed with the same times, cylinder speeds, and cylinder spacing. The cooling system was set to 40° C. and the metal guides were set as to allow the elastomer precursor to occupy 70% of the cylinder surface. The detail proceedings for this process are described in Table 18 below.

TABLE-US-00018 TABLE 18 External mixing procedure. Cylinder Time (min:s) Operation Spacing (mm) t = 00:00 Introduction of the mix from Step 1 1 t = 01:30 Insertion of the curing system 1 (sulfur and accelerators) t = 06:00 3 thin passes 0.5 Calendering sheet, thickness 2 mm 2

[0617] Step 3—Compression Molding

[0618] Sheets of the elastomer composition were produced by compression molding at 160° C. or 180° C. and 100 kgf/cm pressure. This way, small 300×300×2 mm plates were made. The curing time, which determines the molding time, was determined through a rheological MDR test.

[0619] The following elastomer compositions of Table 19 were obtained following the method described above. All elastomer compositions had an isovolumic amount of fillers. The amount of filler was adjusted to match the volume occupied by 40 phr carbon black (powder CE6), depending on the density of the filler (indicated in Table 19 with an asterisk).

TABLE-US-00019 TABLE 19 SBR elastomer compositions (phr: parts per hundred). Example D-E21 D-E22 D-E23 D-CE6 D-CE7 SRB - Buna VSL-2538-2 137.5 137.5 137.5 137.5 137.5 (phr) Powder 21 58.4* Powder 22 44.9* Powder 23 47.8* Powder CE6 (Carbon 40 40 40 80 40 black N220 - Vulcan 6) Powder CE7 61.1* Vivatec 500/plasticizer 16 16 16 16 16 (phr) Protector - 6PPD (phr) 2 2 2 2 2 Protector - Antilux 500 2 2 2 2 2 (phr) ZnO - Silox actif (phr) 3 3 3 3 3 Stearic acid - TP2 (phr) 1.5 1.5 1.5 1.5 1.5 Sulfur (phr) 2 2 2 2 2 CBS (phr) 1 1 1 1 1 MTBS (phr) 0.5 0.5 0.5 0.5 0.5

[0620] The obtained elastomer compositions had the following mechanical properties compiled in Table 20 below.

TABLE-US-00020 TABLE 20 Effect on mechanical properties (series D). M100 Modulus Shore A Compression Tear resistance/ Sample (MPa) Hardness set (%) DELFT (N) D-E21 3.3 55.7 14 28 D-E22 1.8 53.8 11 22 D-E23 1.8 49.8 9 28 D-CE6 1.4 — 23 — D-CE7 0.8 39.2 24 17