Continuous process for reducing molecular weight of ethylene copolymers and terpolymers

Abstract

A continuous process for reducing the molecular weight of ethylene copolymers and terpolymers [EP (D) M] comprising the steps of: (a) providing at least one single screw extruder comprising a chamber, a reciprocating single screw mounted in said chamber, said reciprocating single screw being capable of rotating and oscillating within said chamber, the cavity is provided with at least one feed port and at least one discharge port, and the extruder comprises three conveying and mixing areas, a gear pump and an underwater die surface cutting machine; (b) feeding at least one ethylene copolymer or terpolymer [EP (D) M] into the single screw extruder; (c) conveying the at least one ethylene copolymer or terpolymer [EP (D) M] through a first conveying and mixing zone operating at a temperature of 140 DEG C to 260 DEG C, preferably 150 DEG C to 250 DEG C, where the ethylene copolymer or terpolymer [EP (D) M] is homogeneously mixed and heated and homogeneously softened; (d) conveying the at least one homogeneously softened ethylene copolymer or terpolymer [EP (D) M] leaving the first conveying and mixing zone to a second conveying and mixing zone operating at a temperature of 220 DEG C to 330 DEG C, preferably 230 DEG C to 320 DEG C, wherein the ethylene copolymer or terpolymer [EP (D) M] is further mixed and heated and partially degraded; (e) transporting the at least one partially degraded ethylene copolymer or terpolymer [EP (D) M] exiting the second transport and mixing zone to a third transport and mixing zone operating at a temperature of 170 DEG C to 340 DEG C, preferably 180 DEG C to 330 DEG C, wherein the ethylene copolymer or terpolymer [EP (D) M] is further mixed and heated and further degraded; (f) conveying the at least one further degraded ethylene copolymer or terpolymer [EP (D) M] exiting the third conveying and mixing zone to the gear pump, the gear pump operating at a temperature of 170 DEG C to 340 DEG C, preferably 180 DEG C to 330 DEG C, where the ethylene copolymer or terpolymer [EP (D) M] is further degraded; (g) recovering the at least one further degraded ethylene copolymer or terpolymer [EP (D) M] exiting the subsea die surface cutting machine. The ethylene copolymers and terpolymers [EP (D) M] obtained by the above process are advantageously used as viscosity index improvers (V.I.I.) for lubricating oils.

Description

[0001] The present invention relates to a continuous process for reducing the molecular weight of ethylene copolymers and terpolymers [EP(D)M].

[0002] More specifically, the present invention relates to a continuous process for reducing the molecular weight of ethylene copolymers and terpolymers [EP(D)M], which comprises using a single-screw extruder equipped with a piston screw (“reciprocating single screw”), three conveying and mixing zones, a gear pump, and an underwater strand cutter, and the three conveying and mixing zones and the gear pump operate within a specific temperature range.

[0003] The ethylene copolymers and terpolymers [EP(D)M] obtained by the above method are advantageously used as viscosity index improvers (V.I.I.) for lubricating oils.

[0004] Ethylene copolymers and terpolymers [EP(D)M] are widely used as viscosity index improvers (V.I.I.) in the field of lubricating oil additives [also known as olefin copolymers (OCP) in the industry] in order to adjust the viscosity of the lubricating oil with temperature changes.

[0005] The micro / macrostructure, weight-average molecular weight (Mw), polydispersity index (PDI), i.e., the ratio (Mw / Mn) between the weight-average molecular weight (Mw) and the number-average molecular weight (Mn) of the ethylene copolymers and terpolymers [EP(D)M], and the amount of the ethylene copolymers and terpolymers [EP(D)M] used are all factors that change the effect of the ethylene copolymers and terpolymers as viscosity index improvers (V.I.I.) for lubricating oils and the final properties of the formulations using them.

[0006] Optimization of the micro / macrostructure of ethylene copolymers and terpolymers [EP(D)M] allows finding the right compromise in order to achieve the required technical parameters.

[0007] In addition, since low molecular weight is crucial for the application performance of viscosity index improvers (V.I.I.) for lubricating oils, and the methods (solution process or slurry process) commonly used for producing ethylene copolymers and terpolymers [EP(D)M] usually impart significantly higher molecular weights to the ethylene copolymers and terpolymers [EP(D)M], it is necessary to subject these ethylene copolymers and terpolymers [EP(D)M] to thermal degradation treatment.

[0008] For example, European Patent EP 1013673 relates to a method for reducing the molecular weight of a polymeric material selected from ethylene copolymers and terpolymers [EP(D)M] or mixtures thereof, which comprises treating the polymeric material with at least one hydroperoxide present in an amount sufficient to cause a reduction in molecular weight at a temperature of 80°C to 250°C, and the molar propylene content of the ethylene copolymers and terpolymers [EP(D)M] is 16% to 50%. The resulting ethylene copolymers and terpolymers [EP(D)M] are said to have various applications, including use as a viscosity index improver (V.I.I.) for lubricating oils and modification of high-flow plastics. The above method can be carried out in an extruder (preferably a twin-screw extruder).

[0009] European Patent EP 1671982 relates to a method for preparing a viscosity index improver (V.I.I.) having improved dimensional stability and capable of improving the rheology of low-temperature lubricating oils, the method comprising treating a mixture of linear polyethylene with amorphous ethylene copolymers and terpolymers [EP(D)M], the linear polyethylene being a homopolymer or copolymer of ethylene, characterized by a crystalline structure and having a density of 0.88 to 0.94, the mixture being optionally blended with semi-crystalline ethylene copolymers and terpolymers [EP(D)M], the treatment being carried out in an extruder, the treatment being carried out in the presence of one or more substances of hydroperoxide nature, and optionally, in the presence of a polyfunctional vinyl monomer in an amount of 0 wt% to 2 wt%, the treatment being carried out at a shear value greater than 100 seconds -1 and a temperature of 75°C to 260°C, the amorphous ethylene copolymers and terpolymers [EP(D)M] being characterized by an ethylene content of 35 wt% to 62 wt% and a content of the third monomer of 0 wt% to 10 wt%. The above method can be carried out in an extruder (preferably a twin-screw extruder).

[0010] European Patent EP 1632504 relates to a method for preparing a viscosity index improver (V.I.I.), which comprises treating a composition comprising: (i) one or more ethylene copolymers or terpolymers [EP(D)M] and (ii) one or more polyvinylarylene / hydrogenated conjugated diene / polyvinylarylene block copolymers, the weight ratio of (i) / (ii) being from 98 / 2 to 80 / 20, the method being carried out at a temperature of 150°C to 400°C and a shear value greater than 75 seconds -1 for a time not exceeding 150 seconds. The above method can be carried out in an extruder (preferably a twin-screw extruder).

[0011] European Patent EP 1984479 relates to a method for preparing a viscosity index improver (V.I.I.) for lubricating oils, which comprises mixing and treating a composition under shear conditions greater than 50 seconds -1 The composition comprises:

[0012] (i) one or more ethylene copolymers or terpolymers [EP(D)M];

[0013] (ii) one or more polyethylene arylene / hydrogenated conjugated diene / polyethylene arylene block copolymers;

[0014] (iii) a lubricating oil;

[0015] (ii) is present in a concentration of 1.5 wt% to 20 wt%, and (iii) is present in a concentration of 1.5 wt% to 45 wt%.

[0016] The above method can be carried out in an extruder (preferably a twin-screw extruder).

[0017] Canadian Patent CA 991792 relates to a continuous method for producing a lubricating oil additive, which is carried out by thermally degrading a substantially linear high molecular weight amorphous ethylene-propylene hydrocarbon copolymer in an extruder under non-oxidizing conditions. The copolymer contains 25 wt% - 50 wt% of polymerized propylene, 0 wt% - 5 wt% of polymerized non-conjugated hydrocarbon diene, and the balance is polymerized ethylene. The method comprises: uniformly mixing and heating the copolymer in an initial zone at a temperature of about 150 °C to 280 °C until the copolymer is uniformly melted, the temperature being lower than the degradation temperature of the copolymer; feeding the molten copolymer into a second zone where it is uniformly mixed and heated to a temperature of about 300 °C to 500 °C until a degraded copolymer is obtained, the inherent viscosity of which is lower than the inherent viscosity of the starting copolymer and is 0.1 dl / g to 1.8 dl / g, the inherent viscosity being measured at 30 °C for a 100 ml solution of 0.1 g of the copolymer in tetrachloroethylene, and the molecular weight distribution of which is substantially less than or equal to the molecular weight distribution of the starting copolymer; removing the degraded copolymer from the second zone; cooling and recovering the degraded copolymer, which is substantially colorless or white and contains a non-significant amount of substances insoluble in oil.

[0018] However, the above methods may have some disadvantages. For example, in order to obtain ethylene copolymers and terpolymers [EP(D)M] with a molecular weight suitable for use as viscosity index improvers (V.I.I.), it may be necessary to use hydroperoxides or operate at high temperatures (up to 500 °C), which requires operation in an inert atmosphere (e.g., in the presence of nitrogen), and this may lead to the formation of gels and branching in the final product. In addition, in order to improve the dimensional stability of the resulting ethylene copolymers and terpolymers [EP(D)M], it may be necessary to use small amounts of poly(arylene vinyl) / hydrogenated conjugated diene / poly(arylene vinyl) block copolymers or polyfunctional vinyl monomers.

[0019] Therefore, the present applicant set out to solve the problem of finding a continuous method for reducing the molecular weight of ethylene copolymers and terpolymers [EP(D)M], which can advantageously be used as viscosity index improvers (V.I.I.) for lubricating oils and which can overcome the above disadvantages.

[0020] The present applicant now proposes a continuous method for reducing the molecular weight of ethylene copolymers and terpolymers [EP(D)M], which method comprises using a single-screw extruder equipped with a reciprocating single screw, three conveying and mixing zones, a gear pump, and an underwater strand cutter, the three conveying and mixing zones and the gear pump operating within a specific temperature range. In particular, the present applicant has found that using the single-screw extruder allows operation without hydroperoxides and at lower temperatures than in the prior art in order to avoid operation in an inert atmosphere and the formation of gels and branching in the final product, thereby obtaining ethylene copolymers and terpolymers [EP(D)M] with a molecular weight suitable for use as viscosity index improvers (V.I.I.). In addition, the method does not require the use of poly(arylene vinyl) / hydrogenated conjugated diene / poly(arylene vinyl) block copolymers or polyfunctional vinyl monomers to improve the dimensional stability of the final product.

[0021] Accordingly, an object of the present invention is to provide a continuous method for reducing the molecular weight of ethylene copolymers and terpolymers [EP(D)M], which method comprises the following steps:

[0022] (a) providing at least one single-screw extruder comprising a chamber, a reciprocating single screw mounted in the chamber, the reciprocating single screw being capable of rotating and oscillating within the chamber, the chamber having at least one feed port and at least one discharge port, the extruder comprising three conveying and mixing zones, a gear pump, and an underwater strand cutter;

[0023] (b) feeding at least one ethylene copolymer or terpolymer [EP(D)M] into the single-screw extruder;

[0024] (c) Convey the at least one ethylene copolymer or terpolymer [EP(D)M] through a first conveying and mixing zone operating at a temperature of 140°C to 260°C, preferably 150°C to 250°C, wherein the ethylene copolymer or terpolymer [EP(D)M] is uniformly mixed, heated, and uniformly softened;

[0025] (d) Convey the at least one uniformly softened ethylene copolymer or terpolymer [EP(D)M] exiting the first conveying and mixing zone to a second conveying and mixing zone operating at a temperature of 220°C to 330°C, preferably 230°C to 320°C, wherein the ethylene copolymer or terpolymer [EP(D)M] is further mixed, heated, and partially degraded;

[0026] (e) Convey the at least one partially degraded ethylene copolymer or terpolymer [EP(D)M] exiting the second conveying and mixing zone to a third conveying and mixing zone operating at a temperature of 170°C to 340°C, preferably 180°C to 330°C, wherein the ethylene copolymer or terpolymer [EP(D)M] is further mixed, heated, and further degraded;

[0027] (f) Convey the at least one further degraded ethylene copolymer or terpolymer [EP(D)M] exiting the third conveying and mixing zone to the gear pump, the gear pump operating at a temperature of 170°C to 340°C, preferably 180°C to 330°C, wherein the ethylene copolymer or terpolymer [EP(D)M] is further degraded;

[0028] (g) Recover the at least one further degraded ethylene copolymer or terpolymer [EP(D)M] exiting the underwater die face cutter.

[0029] For the purposes of this specification and the above claims, the definition of a numerical range always includes the extreme values, unless otherwise stated.

[0030] For the purposes of this specification and the above claims, the term "comprising" also includes the terms "consisting essentially of" or "consisting of".

[0031] For the purposes of the present invention, a single-screw extruder equipped with a reciprocating single screw, three conveying and mixing zones, a gear pump, and an underwater die face cutter can be used, and the single-screw extruder further has the following characteristics:

[0032] - Relative to a conventional single-screw extruder in which the screw is in the form of a continuous helix, the reciprocating single screw has threads interrupted at a radial interval of 120°, and pins or teeth cooperating with these threads are inserted into the barrel;

[0033] - Compared with a conventional single-screw extruder in which the movement of the screw consists only of rotation, the movement of this reciprocating single-screw consists of rotation and oscillation. In fact, the rotation of the reciprocating single-screw is superimposed with oscillation (or axial stroke), which results in an improvement in the mixing and degradation capabilities within the extruder;

[0034] - The oscillation frequency of the axial movement (“reciprocating movement”) is the same as the rotational speed, and the gear system ensures that each rotation of the reciprocating single-screw performs a complete forward and backward stroke;

[0035] - The oscillation amplitude is approximately 20 mm;

[0036] - During the execution of the above-mentioned complete forward and backward strokes, the path depicted by the pins (or teeth) covers and cleans the entire surface of the reciprocating single-screw to avoid areas where material stagnation exists. In practice, the threads (“kneading sections”) swing around the pins (or teeth), which allows for a very uniform velocity gradient between the threads (“kneading sections”) and the pins;

[0037] - The combination of the rotation and axial movement of the reciprocating single-screw generates a tensile flow, which has a strong dispersive mixing effect between the threads (“kneading sections”) and the pins;

[0038] - The fusion of the ethylene copolymer or terpolymer [EP(D)M] occurs in the gap between the threads (“kneading sections”) and the pins;

[0039] - Due to the above-mentioned improved mixing capabilities, the ethylene copolymer or terpolymer [EP(D)M] does not exhibit non-uniformity in terms of the solid and molten parts, but rather the ethylene copolymer or terpolymer [EP(D)M] melts simultaneously, resulting in a high viscosity, especially in the first two mixing zones, which generates high shear stress values.

[0040] More details about the above single-screw extruder can be found, for example, in Elemans P.H.M. and Mejer H.E.H, “Polymer Engineering and Science” (1990), mid-August, Volume 30, Issue 15, pages 893 - 904.

[0041] According to a preferred embodiment of the present invention, the single-screw extruder operates at a screw speed of 220 rpm to 300 rpm, preferably 230 rpm to 280 rpm.

[0042] According to a preferred embodiment of the present invention, the single-screw extruder operates at a flow rate of 300 kg / h to 700 kg / h, preferably 400 kg / h to 600 kg / h.

[0043] Upon leaving the underwater profile cutting machine, the degraded ethylene copolymer or terpolymer [EP(D)M] is separated from water in the form of "granules" (e.g., by centrifugation) and subsequently conveyed to the drying and packaging section by pneumatic conveying.

[0044] According to a preferred embodiment of the present invention, the ethylene copolymer or terpolymer [EP(D)M] comprises:

[0045] - 20% to 90% by weight, preferably 40% to 85% by weight, of ethylene relative to the total weight of the ethylene copolymer or terpolymer [EP(D)M];

[0046] - 10% to 80% by weight, preferably 15% to 60% by weight, of propylene relative to the total weight of the ethylene copolymer or terpolymer [EP(D)M];

[0047] - 0% to 12% by weight, preferably 0% to 5% by weight, of non-conjugated diene relative to the total weight of the ethylene copolymer or terpolymer [EP(D)M].

[0048] According to a preferred embodiment of the present invention, the ethylene copolymer or terpolymer [EP(D)M] has the following characteristics:

[0049] - The weight-average molecular weight (Mw) is from 115,000 Da to 500,000 Da, preferably from 120,000 Da to 450,000 Da, more preferably from 125,000 Da to 250,000 Da;

[0050] - The polydispersity index (PDI) (i.e., the ratio (Mw / Mn) between the weight-average molecular weight (Mw) and the number-average molecular weight (Mn)) is less than 5, preferably from 1.8 to 4.5, more preferably from 1.9 to 3.5.

[0051] According to a preferred embodiment of the present invention, the optionally present non-conjugated diene can be selected from, for example, the following:

[0052] - Non-conjugated straight-chain dienes, such as 1,4-hexadiene, 1,6-octadiene;

[0053] - Non-conjugated branched acyclic dienes, such as 5-methyl-1,4-hexadiene, 3,7-dimethyl-1,6-octadiene, 3,7-dimethyl-1,7-octadiene;

[0054] - Non-conjugated monocyclic alicyclic dienes, such as 1,4-cyclohexadiene, 1,5-cyclooctadiene, 1,5-cyclododecadiene;

[0055] - Non-conjugated dienes having fused or bridged alicyclics, such as methyltetrahydroindene, dicyclopentadiene, bicyclo[2.2.1]hepta-2,5-diene, C1-C8-alkenyl-norbornene, C2-C8-alkylene-norbornene, C3-C 12 - cycloalkenyl-norbornene, C3-C 12 - cycloalkylene-norbornene, such as 5-methylene-2-norbornene, 5-ethylidene-2-norbornene (ENB), 5-propenyl-2-norbornene;

[0056] Preferably, the non-conjugated diene is 5-ethylidene-2-norbornene (ENB).

[0057] Amorphous and semi-crystalline ethylene copolymers or terpolymers [EP(D)M], either alone or mixed with each other, can be advantageously used for the purposes of the method of the present invention.

[0058] Ethylene copolymers and terpolymers [EP(D)M] that can be advantageously used for the purposes of the present invention and are currently commercially available are the CO products of Versalis.

[0059] The ethylene copolymers and terpolymers [EP(D)M] obtained by the above method have the following characteristics:

[0060] - The weight-average molecular weight (Mw) is from 50,000 Da to 140,000 Da, preferably from 75,000 Da to 120,000 Da;

[0061] - The polydispersity index (PDI) (i.e., the ratio (Mw / Mn) between the weight-average molecular weight (Mw) and the number-average molecular weight (Mn)) is less than 5, preferably from 1.8 to 4.5, more preferably from 1.9 to 3.5;

[0062] - The thickening power (TP) is from 4 cSt to 7 cSt;

[0063] - The shear stability index (SSI) is from 20% to 30%.

[0064] The above ethylene copolymers and terpolymers [EP(D)M] are advantageously used as viscosity index improvers (V.I.I.) for lubricating oils.

[0065] Preferably, the above ethylene copolymers and terpolymers [EP(D)M] can be used in lubricating oils selected from mineral base oils or synthetic base oils.

[0066] Therefore, another object of the present invention is the use of the ethylene copolymers and terpolymers obtained by the method of the present invention as viscosity index improvers (V.I.I.) for lubricating oils, said lubricating oils preferably being selected from mineral base oils or synthetic base oils.

[0067] Lower Figure 1 Figure 1 shows a block diagram of an embodiment of the method object of the present invention and the equipment and single-screw extruder used in the method, for illustrative and non-limiting purposes only.

[0068] Specifically, in Figure 1 an ethylene copolymer or terpolymer [EP(D)M] (1) is fed through a feed hopper into a single-screw extruder equipped with three conveying and mixing zones, a gear pump, and an underwater die-face cutter, and the three conveying and mixing zones and the gear pump operate within a specific temperature range. In particular, the ethylene copolymer or terpolymer [EP(D)M] (1) passing through the first conveying and mixing zone is uniformly mixed, heated, and uniformly softened to obtain an ethylene copolymer or terpolymer [EP(D)M] (2), which is conveyed to the second conveying and mixing zone, where it is further mixed, heated, and partially degraded to obtain a partially degraded ethylene copolymer or terpolymer [EP(D)M] (3), which is conveyed to the third conveying and mixing zone, where it is further mixed, heated, and further degraded to obtain a further degraded ethylene copolymer or terpolymer [EP(D)M] (4), which is conveyed to the gear pump to obtain a further degraded ethylene copolymer or terpolymer [EP(D)M] (5), which is recovered in the form of "pellets" at the outlet of the underwater die-face cutter, and these "pellets" are separated from water by centrifugation, for example, and then conveyed to the drying and packaging section by pneumatic conveying.

[0069] To better understand the present invention and put it into practice, some illustrative and non-limiting examples of the present invention are reported below.

[0070] The following analysis and characterization methods were used.

[0071] 13 C-NMR and 1 H-NMR spectra

[0072] 13 C-NMR and 1 H-NMR spectra were recorded at 120 °C by a nuclear magnetic resonance spectrometer module. Bruker Avance300, equipped with a 10 mm probe and variable temperature.

[0073] For this purpose, polymer solutions of degraded ethylene copolymers and terpolymers [EP(D)M] obtained by the method object of the present invention were used, which had a concentration of 10% - 15% w / v (g / mL), were prepared at 120 °C using deuterated tetrachloroethane (C2D2Cl4), and tetramethylsilane (TMS) as an internal standard.

[0074] As reported in the literature by Di Martino S., Kelchterrmans M. in “Journal of Applied Polymer Science” (1995), Vol. 56, No. 13, pp. 1781-1787 (Method No. 3, p. 1784), by analyzing the above spectra, the structures of the degraded ethylene copolymers and terpolymers [EP(D)M] obtained as the target by the method of the present invention [i.e., the contents of ethylene (%), propylene (%) and optionally non-conjugated diene] are determined.

[0075] Determination of molecular weight

[0076] By GPC (“Gel Permeation Chromatography”), using the integrated instrument HT-GPC PL220 of Agilent Technologies (which uses three detection lines: refractive index (“IR”), viscometer (“VS”) and dual-angle laser scattering (“DALLS”)), the weight-average molecular weight (Mw), number-average molecular weight (Mn) and polydispersity index (PDI) corresponding to the Mw / Mn ratio of the degraded ethylene copolymers and terpolymers [EP(D)M] obtained as the object by the method of the present invention are measured, and it operates under the following conditions:

[0077] - Pre-column (guard column), size 50x7.5 mm, particle size 10 μm;

[0078] - Three GPC columns of Agilent Technologies, size 300x7.5 mm, particle size 10 μm, with mixed porosity;

[0079] - Mettler XPR 225 analytical balance;

[0080] - Laboratory glassware;

[0081] - Distillation and degassing system for solvent recovery;

[0082] - 50 ml automatic dispenser;

[0083] - pL-SP-260 automatic dissolver of Agilent Technologies;

[0084] - Column injection temperature: 135 °C;

[0085] - Temperature of the column and detection lines: 135 °C;

[0086] - Solvent / eluent: 1,2-dichlorobenzene (99+% for HPLC - Acros OrganicsTM);

[0087] - Flow rate: 1 ml / min;

[0088] - Calculate the molecular weight through a general calibration curve.

[0089] Continuously monitor these operating conditions using a personal computer equipped with Agilent GPC / SEC software from Agilent Technologies.

[0090] Calibration is carried out as follows.

[0091] Prepare a solution containing polystyrene (PS) with a standard nominal peak molecular weight (Mp) of 100 kDa in 1,2-dichlorobenzene (99+% for HPLC - Acros Organics TM) to determine the inter-detector delay (IDD) and the calibration constants for four signals (RID, VS, LS15°, and LS90°).

[0092] Also prepare 7 solutions of 1,2-dichlorobenzene (99+% for HPLC - Acros Organics TM), each containing two monodisperse polystyrene (PS) standards with different nominal peak molecular weights (Mp) and different concentrations: Select the molecular weights such that the eluted chromatographic peaks are well separated, and the concentration of each standard is selected inversely proportional to the molecular weight. The range of different nominal peak molecular weights (Mp) of the standards used for the calibration curve is from 2 kDa to 7000 kDa.

[0093] Prepare different solutions in the above-mentioned PL-SP-260 automatic dissolver from Agilent Technologies under stirring at room temperature (25 °C).

[0094] Use a personal computer equipped with Agilent GPC / SEC software from Agilent Technologies to calculate the calibration curve using a third-order polynomial function.

[0095] Determination of thickening power (TP)

[0096] Determine the thickening power (TP) according to ASTM D7042-04.

[0097] Determination of shear stability index (SSI)

[0098] Determine the shear stability index (SSI) according to ASTM D7109-12.

[0099] Example 1 (the present invention)

[0100] An amorphous ethylene-propylene copolymer having the following CO 058 (Versalis):

[0101] - 54 wt% ethylene;

[0102] - 46 wt% propylene;

[0103] - weight average molecular weight (Mw) of 190,000 Da;

[0104] - polydispersity index (PDI) of 2.2;

[0105] Feed at a flow rate of 500 kg / h into a single-screw extruder with a reciprocating screw (BUSS MDK 140 from Aaron Equipment), which is equipped with three conveying and mixing zones, a gear pump, and an underwater die-face cutter with a diameter of 140 mm, and the ratio of length (L) to diameter (D) (L / D) is equal to 11. The extruder operates under the following conditions:

[0106] - Screw rotation speed: 260 rpm;

[0107] - Temperature profile in the first zone: 160 °C - 210 °C;

[0108] - Temperature profile in the second zone: 270 °C - 310 °C;

[0109] - Temperature profile in the third zone: 280 °C - 320 °C;

[0110] - Gear pump temperature: 280 °C - 320 °C.

[0111] Upon leaving the underwater die-face cutter (cutting speed equal to 2700 rpm), the degraded and cooled copolymer is recovered in the form of "pellets", and these "pellets" are centrifuged to separate them from water, and then conveyed by pneumatic transportation to the drying and packaging section.

[0112] The obtained degraded copolymer is subjected to NMR and GPC ("gel permeation chromatography") analysis as described above to obtain the following values:

[0113] - 54 wt% ethylene;

[0114] - 46 wt% propylene;

[0115] - weight average molecular weight (Mw) of 80,000 Da;

[0116] - polydispersity index (PDI) of 2.2.

[0117] Example 2 (the present invention)

[0118] A mixture consisting of:

[0119] - 70 wt% of a semi-crystalline ethylene-propylene copolymer CO 034 (Versalis), which has the following characteristics:

[0120] - 68 wt% of ethylene;

[0121] - 32 wt% of propylene;

[0122] - A weight-average molecular weight (Mw) of 130,000 Da;

[0123] - A polydispersity index (PDI) of 2.2;

[0124] - 30 wt% of an amorphous ethylene-propylene copolymer having the above characteristics CO 058 (Versalis);

[0125] Is fed at a flow rate of 500 kg / h into a single-screw extruder (BUSS MDK 140 from Aaron Equipment) with a reciprocating screw, which is equipped with three conveying and mixing zones, a gear pump, and an underwater die-face cutter with a diameter of 140 mm, and the ratio of the length (L) to the diameter (D) (L / D) is equal to 11. The extruder operates under the following conditions:

[0126] - Screw speed: 280 rpm;

[0127] - Temperature profile in zone 1: 180 °C - 240 °C;

[0128] - Temperature profile in zone 2: 250 °C - 300 °C;

[0129] - Temperature profile in zone 3: 190 °C - 300 °C.

[0130] - Gear pump temperature: 190 °C - 300 °C.

[0131] Upon leaving the underwater die-face cutter (cutting speed equal to 2700 rpm), the degraded and cooled copolymer is recovered in the form of "pellets", and these "pellets" are centrifuged to separate them from water and then conveyed by pneumatic conveying to the drying and packaging section.

[0132] The obtained degraded copolymer is subjected to NMR and GPC ("gel permeation chromatography") analysis as described above to obtain the following values:

[0133] - 63.5 wt% of ethylene;

[0134] - 36.5 wt% of propylene;

[0135] - A weight-average molecular weight (Mw) of 85,000 Da;

[0136] - The polydispersity index (PDI) was 2.2.

[0137] Example 3 (comparison)

[0138] An amorphous ethylene-propylene copolymer having the following CO 058 (Versalis):

[0139] - 54 wt% ethylene;

[0140] - 46 wt% propylene;

[0141] - The weight-average molecular weight (Mw) was 190,000 Da;

[0142] - The polydispersity index (PDI) was 2.2;

[0143] was fed at a flow rate of 1 kg / h to a single-screw extruder (Goettfert 20D from Goetffert GmBH) without a reciprocating screw, equipped with three conveying and mixing zones and a die with a diameter equal to 2 mm and a ratio of length (L) to diameter (D) equal to 20. The extruder was operated under the following conditions:

[0144] - Screw rotation speed: 100 rpm;

[0145] - Temperature profile in zone 1: 160 °C - 180 °C;

[0146] - Temperature profile in zone 2: 290 °C - 310 °C;

[0147] - Temperature profile in zone 3: 300 °C - 320 °C;

[0148] - Cooling in a water bath.

[0149] Upon leaving the die, the degraded and cooled copolymer was recovered in the form of air-dried "spaghetti".

[0150] The copolymer obtained was subjected to NMR and GPC ("gel permeation chromatography") analysis as described above to obtain the following values:

[0151] - 54 wt% propylene;

[0152] - 46 wt% ethylene;

[0153] - The weight-average molecular weight (Mw) was 150,000 Da;

[0154] - The polydispersity index (PDI) was 2.2.

[0155] Example 4 (comparison)

[0156] A mixture consisting of:

[0157] - 70 wt% of a semi-crystalline ethylene-propylene copolymer CO 034 (Versalis), which has the following characteristics:

[0158] - 68 wt% of ethylene;

[0159] - 32 wt% of propylene;

[0160] - A weight-average molecular weight (Mw) of 130,000 Da;

[0161] - A polydispersity index (PDI) of 2.2;

[0162] - 30 wt% of an amorphous ethylene-propylene copolymer having the above characteristics CO 058 (Versalis);

[0163] Is fed at a flow rate of 1 kg / h to a single-screw extruder (Goettfert 20D, manufactured by Goetffert GmBH) without a reciprocating screw, which is equipped with three conveying and mixing zones and a die with a diameter equal to 2 mm and a ratio of length (L) to diameter (D) equal to 20. The extruder operates under the following conditions:

[0164] - Rotational speed of the screw: 100 rpm;

[0165] - Temperature profile in zone 1: 160 °C - 180 °C;

[0166] - Temperature profile in zone 2: 270 °C - 300 °C;

[0167] - Temperature profile in zone 3: 290 °C - 320 °C;

[0168] - Cooled in a water bath.

[0169] Upon leaving the die, the degraded and cooled copolymer is recovered in the form of air-dried "spaghetti".

[0170] The obtained copolymer is subjected to NMR and GPC ("gel permeation chromatography") analysis as described above to obtain the following values:

[0171] - 63.5 wt% of propylene;

[0172] - 36.5 wt% of ethylene;

[0173] - A weight-average molecular weight (Mw) of 160,000 Da;

[0174] - The polydispersity index (PDI) is 2.2.

[0175] Example 5 (the present invention)

[0176] Evaluation of lubricating oil viscosity index improver (V.I.I.)

[0177] To this end, the degraded ethylene-propylene copolymers (EPRs) obtained in Examples 1 (the present invention), 2 (the present invention), 3 (comparative), and 4 (comparative) were dissolved in a reference base oil SN 150 Group I (Eni S.p.A.) in an amount equal to 1 wt%.

[0178] The thickening power (TP) was determined according to ASTM D7402-04 and the shear stability index (SSI) was determined according to ASTM D7109-12 using the obtained solutions, as listed above: The results are shown in Table 2.

[0179] The SN 150 base oil has the following characteristics:

[0180] - The kinematic viscosity (KV) at -100 °C is equal to 5.3 cSt;

[0181] - The pour point is equal to -15 °C.

[0182] Table 2

[0183]

[0184]

[0185] The data in Table 2 show that the ethylene-propylene copolymers (EPRs) obtained using a non-reciprocating single-screw extruder [Example 3 (comparative) and Example 4 (comparative)] do not give the desired results when used as viscosity index improvers.

Claims

1. A continuous process for reducing the molecular weight of ethylene copolymers and terpolymers [EP(D)M], which comprises the following steps: (a) Providing at least one single-screw extruder, which comprises a chamber, a reciprocating single screw installed in the chamber, the reciprocating single screw being capable of rotating and oscillating in the chamber, the chamber having at least one feed port and at least one discharge port, and the extruder comprising three conveying and mixing zones, a gear pump, and an underwater die face cutter; (b) Feeding at least one ethylene copolymer or terpolymer [EP(D)M] into the single-screw extruder; (c) Conveying the at least one ethylene copolymer or terpolymer [EP(D)M] through a first conveying and mixing zone, which operates at a temperature of 140°C to 260°C, preferably 150°C to 250°C, wherein the ethylene copolymer or terpolymer [EP(D)M] is uniformly mixed, heated, and uniformly softened; (d) Conveying the at least one uniformly softened ethylene copolymer or terpolymer [EP(D)M] leaving the first conveying and mixing zone to a second conveying and mixing zone, which operates at a temperature of 220°C to 330°C, preferably 230°C to 320°C, wherein the ethylene copolymer or terpolymer [EP(D)M] is further mixed, heated, and partially degraded; (e) Conveying the at least one partially degraded ethylene copolymer or terpolymer [EP(D)M] leaving the second conveying and mixing zone to a third conveying and mixing zone, which operates at a temperature of 170°C to 340°C, preferably 180°C to 330°C, wherein the ethylene copolymer or terpolymer [EP(D)M] is further mixed, heated, and further degraded; (f) Conveying the at least one further degraded ethylene copolymer or terpolymer [EP(D)M] leaving the third conveying and mixing zone to the gear pump, which operates at a temperature of 170°C to 340°C, preferably 180°C to 330°C, wherein the ethylene copolymer or terpolymer [EP(D)M] is further degraded; (g) Recovering the at least one further degraded ethylene copolymer or terpolymer [EP(D)M] leaving the underwater die face cutter.

2. The continuous process for reducing the molecular weight of ethylene copolymers and terpolymers [EP(D)M] according to claim 1, wherein the single-screw extruder operates at a screw speed of 220 rpm to 300 rpm, preferably 230 rpm to 280 rpm.

3. The continuous process for reducing the molecular weight of ethylene copolymers and terpolymers [EP(D)M] according to claim 1 or 2, wherein the single-screw extruder operates at a flow rate of 300 kg / h to 700 kg / h, preferably 400 kg / h to 600 kg / h.

4. A continuous process for reducing the molecular weight of ethylene copolymers and terpolymers [EP(D)M] according to any one of the preceding claims, wherein the ethylene copolymer or terpolymer [EP(D)M] comprises: - from 20% to 90% by weight, preferably from 40% to 85% by weight, of ethylene, relative to the total weight of the ethylene copolymer or terpolymer [EP(D)M]; - from 10% to 80% by weight, preferably from 15% to 60% by weight, of propylene, relative to the total weight of the ethylene copolymer or terpolymer [EP(D)M]; - from 0% to 12% by weight, preferably from 0% to 5% by weight, of non-conjugated diene, relative to the total weight of the ethylene copolymer or terpolymer [EP(D)M].

5. A continuous process for reducing the molecular weight of ethylene copolymers and terpolymers [EP(D)M] according to any one of the preceding claims, wherein the ethylene copolymer or terpolymer [EP(D)M] has the following characteristics: - The weight-average molecular weight (M w ) is from 115,000 Da to 500,000 Da, preferably from 120,000 Da to 450,000 Da, and more preferably from 125,000 Da to 250,000 Da; - Polydispersity index (PDI), i.e., the ratio between the weight-average molecular weight (M w ) and the number-average molecular weight (M n ), (M w / M n ), is less than 5, preferably from 1.8 to 4.5, more preferably from 1.9 to 3.

5.

6. A continuous process for reducing the molecular weight of ethylene copolymers and terpolymers [EP(D)M] according to claim 4, wherein the optionally present non-conjugated diene is selected from the following: - non-conjugated straight-chain dienes, such as 1,4-hexadiene, 1,6-octadiene; - non-conjugated branched non-cyclic dienes, such as 5-methyl-1,4-hexadiene, 3,7-dimethyl-1,6-octadiene, 3,7-dimethyl-1,7-octadiene; - non-conjugated monocyclic alicyclic dienes, such as 1,4-cyclohexadiene, 1,5-cyclooctadiene, 1,5-cyclododecadiene; - Non-conjugated dienes having fused or bridged alicyclics, such as methyltetrahydroindene, dicyclopentadiene, bicyclo[2.2.1]hepta-2,5-diene, C1-C8-alkenyl-norbornene, C2-C8-alkylene-norbornene, C3-C 12 - cycloalkenyl-norbornene, C3-C 12 - cycloalkylene-norbornene, such as 5-methylene-2-norbornene, 5-ethylene - 2-norbornene (ENB), 5-propenyl-2-norbornene; Preferably, the non-conjugated diene is 5-ethylidene-2-norbornene (ENB).

7. Use of an ethylene copolymer and terpolymer [EP(D)M] obtained by the process according to any one of the preceding claims as a viscosity index improver (V.I.I.) for lubricating oils, which lubricating oils are preferably selected from mineral base oils or synthetic base oils.

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