WO2025132861A1 - Polyolefin polymers with low content of volatiles - Google Patents

Abstract

A process for providing an EPDM polymer with a reduced content of volatile ENB said process comprises (i) providing an EPDM polymer comprising from 1 % to 20 % by weight of units derived from ENB, based on the total weight of the EPDM polymer, (ii) treating the EPDM polymer of step (i) with superheated steam to reduce the volatile ENB content of the EPDM polymer; (iii) ceasing the treatment with superheated steam, (iv) optionally, cooling the polymer to room temperature.

Description

Polyolefin polymers with low content of volatiles

Field

The present disclosure relates to a process for producing polyolefin polymers having a low content of volatiles, to the polymers produced by that process and their applications.

Background

Most commercial processes for producing polyolefins involve the removal of solvents and unused monomers, which is typically achieved by dry finishing or steam stripping. In the production of EPDM rubbers, monomers with a norbornene structure, such as ethylidene norbornene (ENB) and vinyl norbornene (VNB), are frequently used to provide cross-linking or branching sites. These comonomers are difficult to remove completely by dry finishing or steam stripping and they are malodorous even at very low concentrations. Therefore, there is a need to provide a process for providing polyolefin polymers with low content of norbornenes, such as ENB or VNB or both.

Summary

Therefore, in one aspect there is provided a process for providing an EPDM polymer with a reduced content of volatile ENB said process comprises:

(i) providing an EPDM polymer comprising from 1 % to 20 % by weight of units derived from ENB, based on the total weight of the EPDM polymer,

(ii) treating the EPDM polymer of step (i) with superheated steam to reduce the volatile ENB content of the EPDM polymer;

(iii) ceasing the treatment with superheated steam,

(iv) optionally, cooling the polymer to room temperature.

In another aspect there is provided a polymer composition comprising at least 95% by weight, or at least 99% by weight, of an EDPM polymer having units derived from 1 to 20 % by weight of ENB and, optionally, from 0.2 to 10 % by weight of VNB, wherein the polymer composition has a volatile content of ENB of less than 1 .5 ppm or less than 0.95 ppm or less than 0.60 ppm.

In a further aspect there is provided a process of making a TPV comprising (i) extruding a blend produced by combining the polymer composition with a thermoplastic polymer, preferably a polypropylene polymer, and (ii) extruding the resulting mixture in the presence of at least one curing agent to produce a TPV, wherein the blend is produced prior or during the extrusion. In yet another aspect there is provided an article obtained with the polymer composition.

Figures

Figure 1 shows a diagram indicating temperature-pressure relationship and drying capacity of steam. The upper solid line is a plot of temperature versus pressure of steam. The lower solid line shows the temperature of the superheated steam when the pressure was dropped to 1 bar from the respective pressure of the corresponding temperature-pressure curve. The dotted line shows the drying capacity of supersaturated steam.

Description

In the following description the terms "comprising,'' “containing”, "including," "having," are used in an open meaning and do not exclude the presence of any additional component, step or procedure, whether or not the same is specifically disclosed. For example, the term “a composition comprising components A and B” means that components other than A and B may also be present in the composition. The term “consisting of’ is used in a limiting meaning to exclude the presence of any additional component, step or procedure. For example, the term “a composition consisting of components A and B” means that no components other than A and B are present in the composition.

In the following description norms may be used. If not indicated otherwise, the norms are used in the version that was in force on March 1 , 2020. If no version was in force at that date because, for example, the norm has expired, the version is referred to that was in force at a date that is closest to March 1 , 2020.

In the following description the amounts of ingredients of a composition or polymer may be indicated by “weight percent”, “wt. %” or “% by weight”. The terms “weight percent", “wt. %” or “% by weight” are used interchangeably and are based on the total weight of the composition or polymer, respectively, which is 100 % unless indicated otherwise.

The term “phr” means parts per hundred parts of rubber, i.e. , the weight percentage based on the total amount of rubber which is set to 100%.

Ranges identified in this disclosure are meant to include and disclose all values between the endpoints of the range and include the end points unless stated otherwise. The present disclosure provides a process for reducing the content of volatile content of norbornenes in EPDM polymers. Norbornenes include ethylidene norbornene (ENB), vinyl norbornene (VNB) and a combination thereof. The process includes treating an EPDM polymer with superheated steam. The treatment is carried out for an effective time to reduce the content of volatile norbornenes of the polymer. The volatile content refers to the amount of residual norbornene monomers, preferably ENB, VNB or their combination, in the polymer. These residual monomers can gas out and are perceived as malodour. The volatile content can be determined by GC-MS as described in the experimental section. The effective time depends on the amount of volatile norbornenes present in the EPDM polymer, the temperature of the superheated steam, the contact time of the superheated steam and on the particle size of the EPDM polymer subjected to the treatment. The effective time can be identified by routine experimentation and the examples provided in this description can be used as guidance. For example, the volatile content of an EPDM polymer having a volatile content of 10 ppm can be removed to less than 1 ppm within less than 30 minutes.

In one embodiment of the present disclosure the process according to the present disclosure provides an EPDM polymer having a content of volatile ENB of less than 1 .5 ppm or less than 1.0 ppm or less than 0.60 ppm. In one embodiment the process provides an EPDM polymer having a volatile content of ENB of from 0.2 up to 0.4 ppm.

In one embodiment of the present disclosure the process according to the present disclosure provides an EPDM polymer having a content of volatile VNB of from 0.01 to 1 .4 ppm or from 0.01 to 0.90 ppm or from 0.03 up to 0.5 ppm. In one embodiment the process provides an EPDM polymer having a volatile content of VNB of from 0.02 up to 0.04.

In one embodiment of the present disclosure the process according to the present disclosure provides an EPDM polymer having a combined content of volatile ENB and VNB of less than 1 .5 ppm, or less than 0.95 ppm or less than 0.60 ppm. In one embodiment the process provides an EPDM polymer having a combined volatile content of ENB and VNB of from 0.2 to 0.4 ppm. Preferably the content of volatile VNB in the combined content of volatile ENB and VNB is at least 0.01 ppm or at least 0.02 ppm.

Superheated steam is steam at a temperature higher than its boiling point for the pressure, which only occurs when all liquid water has evaporated or has been removed. Therefore, supersaturated steam is steam in which the operating temperature of the gas (i.e., steam) exceeds that of the saturated steam temperature at the given operating pressure of interest. Superheated steam is physically produced by the addition of heat to saturated steam (being a mixture of both the liquid and gaseous phases of water), whereby the liquid phase has been removed in its entirety. Once the liquid phase has been eliminated, the addition of heat causes the temperature of the steam to increase beyond its associated saturation temperature. The resulting properties of the superheated steam then closely approximate those of a perfect gas as opposed to the mixed phase vapor associated with the saturated steam environment. In comparison with saturated steam, whose temperature is bounded while the presence of liquid water exists, superheated steam in the pure gaseous form can reach temperatures consistent with the degree of heating supplied by the respective source of heat. In addition, superheated steam cannot condense (i.e., creating the presence of liquid water) without its temperature being reduced to the temperature of saturated steam at the pressure of interest. As long as the gas temperature is above that of saturated steam at the corresponding pressure, it is in the superheated regime and before condensation is possible, the number of degrees of superheat must vanish through some method or combination of methods of heat transfer (i.e., conduction, convection, and radiation).

Superheated steam can be generated by commercial devices ("superheaters”) or by methods known to the person skilled in the art. For example, saturated steam can be generated by boiling water in a pressurized boiler to create saturated steam at elevated pressure. The saturated steam can be released via a nozzle to a lower pressure, for example ambient pressure, which causes the temperature to drop while creating a supersaturated steam. The pressurized boiler is kept at boiling conditions and elevated pressure to continue producing saturated steam such that a steady supply of superheated steam can be generated. Figure 1 provides the pressure/temperature curves for steam, produced for example in a boiler. When this steam is released to ambient pressure of 1 bar the temperature will drop as shown (lower solid line). This steam is then supersaturated and has a certain dryness which allows to remove volatile norbornenes. Preferably, superheated steam is used that has a temperature of at least 100°C, for example between 105°C and 200°C, preferably between 110°C and 180°C or between 120°C and 160°C. Preferably, the treatment is carried out at ambient pressure, i.e., at 1 bar +/- 10%. Higher or lower pressures may be used in which case the preferred temperature range may be different.

The EPDM polymer treated with the process according to the present disclosure is preferably present in solid form, preferably in particulate from, for example in the form of granules, crumbs or pellets. The size of the polymer particles is not particularly limited but preferably the particle size is greater than 1 mm (in at least one dimension) to avoid caking. Polymer crumbs are typically obtained from the work up procedure of the polymerization process, typically after the solvent has been removed. Granules are typically obtained from grinding polymer bales, for example by granulators or other comminution means. Pellets are typically obtained by extrusion of the polymer and cutting the extruded strand into thin sections, which typically creates cylindrically shaped particles. The pellets may have a diameter at least 5 mm and a length, perpendicular to the diameter, of at 5 mm. Typically, the length and/or diameter of the pellets is less than 20 cm, preferably less than 10 cm. Preferably, EPDM polymer particles are used that have a moisture content below 10%, preferably below 5%, more preferably below 2%. Moisture will be removed by superheated steam together with the volatile norbornenes, but the process is faster and more efficient when the moisture content is kept low.

Preferably, the polymer particles are at a temperature about the boiling point of water at the applied pressure, preferably at about 100°C at ambient pressure, when they are subjected to the treatment with superheated steam. The particles may be brought to this temperature by using superheated steam or other means, for example particles may be used that have been obtained directly from the extruder, for example a dewatering extruder or a pellet extruder. Polymer particles may be heated, for example, by using saturated steam and removing condensed water.

The treatment with superheated steam may be carried out in any suitable vessel or a plurality thereof. The treatment may be a single treatment or may be carried out multiple times and at intervals. Preferably, the treatment is carried out continuously with superheated steam being continuously removed and replaced with fresh supplied superheated steam. The vessel may have one or more nozzles through which the superheated steam is fed into the vessel and one or more outlet for the superheated steam. The treatment may be carried out in a single vessel or in a series of vessels, for example in parallel or in sequence. Preferably, the particles are moved during the treatment, for example by a stirrer or an extruder screw or by the flow, preferably turbulent flow, created by superheated steam for effective treatment but also to prevent agglomeration. The vessel may be equipped with additional mechanical comminution devices such as knives, spikes, choppers, or grinders as known in the art to avoid agglomeration and formation of lumps. Alternatively, the polymer may be fed through one or more comminution devices after its treatment with superheated steam.

After the treatment with superheated steam the particles are cooled down. The cooling step can be carried out with ambient air under moderate flow until conditions are met for packaging into bags or pressing into bales. This superheated steam can be cooled and condensed, for example, by heat exchangers. The condensed water can be recycled after treating it with purifying means, for example active carbon or other absorbing materials, for removing the volatile norbornenes it contains. The treated polymer may be subjected to one or more shaping process. For example, instead of using pellets as starting materials, pellets may be formed after the treatment with the superheated steam. Also “repelletizing” may be carried out, i.e., the pellets were subjected to additional pelletizing to increase or decrease their size or change their shape.

The process according to the present disclosure may be carried out continuously or as a batch process.

EPDM polymers

In principle any EPDM polymer can be subjected to the process according to the present disclosure. The process according to the present disclosure only reduces the volatile content of the EPDM polymer but does not change the composition of the polymer, i.e., the amount of polymerized units, its molecular weight, polymer architecture, e.g. degree of branching or polydispersity, or its properties, such as, for example the Mooney viscosity or its mechanical properties.

The EPDM polymers may have a molecular weight (Mw) of at least 50 kg/mol, at least 90 kg/mol, at least 120kg/mol or even at least 200 kg/mol. In one embodiment of the present disclosure the EPDM polymer has a molecular weight (Mw) of from 50 kg/mol to 150 kg/mol. In another embodiment of the present disclosure, the polymer has an Mw of at least 200kg/mol, for example from about 200 kg/mol to about 600 kg/mol or from about 200kg/mole to about 500 kg/mol. Polymers of higher molecular weight, e.g. EPDM polymer having a molecular weight of at least 200 kg/mol have been found to be less sticky at high temperatures, for example at temperature around 100°C or above as may be applied in the process according to the present disclosure. Therefore, the process according to the present disclosure is particularly suitable for EPDM polymers having a molecular weight Mw of at least 200kg/mol, at least 250 kg/mol, at least 300 kg/mol, at least 375 kg/mol, at least 425 kg/mol, at least 530 kg/mol or at least 600 kg/mol.

The polymers may have a high or low number average molecular weight (Mn). In one embodiment the polymer used in the process according to the present disclosure has an Mn of from 40kg/mol to 250 kg/mol.

The EPDM polymers may have a Mooney viscosity, ML 1+4 at 125°C of from 20 and up to 200, preferably from 20 to 150, more preferably at least 50 or at least 65 or at least 75. Branched or linear polymers may be used. Preferably, the EPDM polymer is branched and preferably contains units derived from a norbornene that creates branches, like VNB - although other means for creating polymer branches may be applied in addition or instead of using VNB. The branching level can be characterized by the parameter A3. A3, expressed in degrees, is the difference between the phase angle 8 at a frequency of 0.1 rad/s and the phase angle 8 at a frequency of 100 rad/s, as determined by Dynamic Mechanical Spectroscopy (DMS) at 125 °C and 10% strain. The A3 as a measure for the amount of long chain branched structures in the polymer has been introduced in H.C. Booij, Kautschuk + Gummi Kunststoffe, Vol. 44, No. 2, pages 128-130, which is incorporated herein by reference. The lower the A3, the more branched structures are present in the polymer. In one embodiment of the present disclosure the EPDM polymer has a A8 of from 1 to 50. Preferably, the EPDM polymer has a A3 of from 2 to 20 or from 3 to 15.

The polymers that may be used in the process according to the present disclosure may be monomodal, bimodal or multimodal, i.e., they may have molecular weight distributions featuring two peaks in case of bimodal polymers or more than two peaks in case of multimodal polymers in a diagram obtained by gel permeation chromatography (GPC). Polymer blends may be used, also.

In one embodiment of the present disclosure the EPDM polymer comprises at least 20% by weight or at least 30% by weight of units derived from ethylene. In one embodiment of the present disclosure the EPDM comprises from 40 to 70 wt.%, preferably from 44 to 68 wt. % or from 50 to 60 wt.% of units derived from ethylene. The weight percentages are based on the total weight of the copolymer.

The ethylene used for making the EPDM polymer may be of fossil origin or may be obtained from a sustainable source, for example selected from a plant-based source or from a recycled material, which may be a plant-based material or not plant-based. The use of products derived from natural sources, as opposed to those obtained from fossil sources, has become of increased interest as an effective means of reducing the increase in atmospheric carbon dioxide concentration, and thus contributing to reducing the greenhouse effect. Products obtained from natural raw materials differ from fossil sourced products, only in their renewable carbon contents. This renewable carbon content can be certified by the methodology described in the technical ASTM D 6866-18 Norm, “Standard Test Methods for Determining the Biobased Content of Solid, Liquid, and Gaseous Samples Using Radiocarbon Analysis”. In other words, products containing carbon obtained from a natural source have a different amount of C14 isotopes than those obtained from fossil sources but are chemically completely identical. The renewable source of carbon may include one or more plant materials selected from the group consisting of sugarcane, sugar beet, maple, date palm, sugar palm, sorghum, American agave, corn, wheat, barley, sorghum, rice, potato, cassava, sweet potato, algae, and fruit. The renewable source of carbon may also include materials comprising cellulose, including wood, straw, paper, wood or paper pulp and leaves. Biobased ethylene may be obtained, for example, by fermenting a renewable source of carbon to produce ethanol, which may be subsequently dehydrated to produce ethylene. Higher alcohols may be formed as by-products during the fermentation and the biobased ethanol, typically is purified prior to dehydration. In addition, or as alternative, the bio-based ethylene may be purified, for example distilled, to remove impurities. Biologically sourced ethanol, known as bioethanol, may be obtained by the fermentation of sugars derived from cultures such as that of sugarcane and beets, or from hydrolysed starch, which is, in turn, associated with other cultures such as corn. Bio-based ethylene may be obtained from hydrolysis-based products of cellulose and hemicellulose, which can be found in many agricultural by-products, such as straw and sugarcane husks. The fermentation may be carried out in the presence of varied microorganisms, for example the yeast Saccharomyces cerevisiae. The resulting ethanol may be converted into ethylene for example by a catalytic reaction at temperatures above 300° C. A large variety of catalysts can be used for this purpose. Examples to produce bioethanol and its conversion into ethylene include U.S. Pat. Nos. 9,181 ,143 and 4,396,789.

In addition to units derived from ethylene the polymer according to the present disclosure contains units derived from one or more alpha olefins. Alpha-olefins are olefins having a single aliphatic carbon-carbon double bond. The double bond is located at the terminal end (alpha-position) of the olefin. The a-olefins can be aromatic or aliphatic, linear, branched, or cyclic. Typically, the alpha-olefins have from 3 to 20 carbon atoms. Preferred examples of alpha-olefins include but are not limited to propylene, 1 -butene, 1 -pentene, 1 -hexene, 1 -heptene, 1 -octene, 1 -nonene, 1- decene, 1 -undecene, 1 -dodecene, 1 -tridecene, 1 -tetradecene, 1 -pentadecene, 1 -hexadecene, 1- hepta-decene, 1 -octadecene, 1 -nonadecene, 1-eicosene, 3-methyl-1 -butene, 3-methyl-1- pentene, 3-ethyl-1 -pentene, 4-methyl-1 -pentene, 4-methyl-1 -hexene, 4, 4-dimethyl-1 -hexene, 4, 4-dimethyl-1 -pentene, 4-ethyl-1 -hexene, 3-ethyl-1 -hexene, 9-methyl-1 -decene, 11-methyl-1- dodecene and 12-ethyl-1 -tetradecene. Several alpha olefins may be used in combination. Preferably, the alpha-olefin is propylene. Preferably, the EPDM polymer comprises at least 20% by weight, preferably at least 29% by weight of units derived from propylene, based on the total amount of polymer. The alpha-olefin used may be of fossil origin or may be obtained from a sustainable source, including but not limited to recycled material.

In addition to ethylene and alpha olefin the EPDM polymer contains units derived from at least one norbornene, preferably from ENB, VNB or a combination thereof. In a typical embodiment of the present disclosure the EPDM polymer contains at least 2 wt. % and up to and including 20 wt. % of units derived from one or more norbornene. Preferably, the EPDM polymer comprises from at least 2 wt. % and up to and including 20 wt. % of units derived from ENB, more preferably from at least 3 wt. % and up to and including 15 wt. %. In addition, or as alternative to ENB, the EPDM polymer comprises units derived from VNB, for example from 0.2 to 10% by weight or from about 0.05 wt. % to about 5 wt. %, preferably from 0.10 wt. % to 3 wt. % or from 0.15 wt. % to 1 .2 wt. % of units derived from VNB. In one embodiment of the present disclosure, the EPDM polymer comprises from 2 to 15 wt. % of units derived from ENB and from 0.05 to 4 wt. % of units derived from VNB.

In one embodiment, the EPDM polymer only has units derived from ethylene, propylene, ENB, optionally VNB, and has units from one or more further co-polymerizable monomer, including but not limited to, linear or branched alpha-omega dienes, cyclic dienes and combinations thereof. In one embodiment, the EPDM polymer only has units derived from ethylene, propylene, ENB and, optionally, VNB.

The EPDM polymers to be used in the process of the present disclosure may be obtained by any known process. The polymerization can be carried out in the gas phase, in a slurry, or in solution in an inert solvent, preferably a hydrocarbon solvent. The polymerization may be carried out continuously, for example in one or more continuously stirred tank reactors, one or more loop rectors, or as a batch reaction in one or more batch reactors or a combination thereof. The continuous reaction may be carried out adiabatically or non-adiabatically. Multiple reactors may be used and may be connected in series or in parallel. Solvents and monomers may be chilled prior to entering the reaction for temperature control or may be evaporated for temperature control. Preferably, the EPDM polymers are obtained by solution polymerization. Preferred solvents include one or more inert hydrocarbon solvent. Suitable solvents include C5-12 hydrocarbons such as pentane, hexane, heptane, octane, cycloheptane, cyclohexane, methyl cyclohexane, methyl cycloheptane, pentamethyl heptane, hydrogenated naphtha, isomers and mixtures thereof. In another embodiment the polymerization is carried out as a slurry polymerization. The polymerization may include the use of one or more chain transfer agents to control the molecular weight of the polymer. Chain transfer agent includes hydrogen, compounds with reactive hydrogen, diethyl zinc and combinations thereof.

The EPDM polymers may be produced by using one or more than one conventional polymerization catalysts, suitable for use in the polymerization of the respective polymer to be produced. Typical examples include Ziegler-Natta-catalysts, organometallic catalysts, or metallocene-type catalysts. Ziegler-Natta catalysts are polymerization catalysts based on halides of transition metals, in particular titanium or vanadium. Metallocene-type catalysts are organometallic catalysts wherein a metal, typically Ti, Hf, or Zr, is bonded to at least one cyclic organic ligand, preferably at least one cyclopentadienyl-based, fluorenyl-based or indenyl-based ligand. Catalysts where the metal is bonded to two anionic aromatic ligands are typically referred to in the art as “metallocene catalysts”. Catalysts wherein the second anionic aromatic ligand is replaced by another organic ligand are referred to as “half-metal locene catalysts”. Metal catalysts where both anionic ligands are replaced with organic residues are referred to in the art as “postmetallocene catalysts”. Metallocene-type catalysts include metallocene, post-metallocene and half-metallocene catalysts. Suitable metallocene-type polymerization catalysts are known in the art and are described in, for example, W02005/090418 A1 , WO2016/114914A1 , WO2017/048448, US2015/0025209A1 , all incorporated herein by reference.

One or more cocatalysts may be used in the polymerization. The cocatalysts are also referred to in the art as “activators”. The presence of cocatalysts typically increases the rate at which the catalyst polymerizes the olefins. The cocatalyst can also affect the molecular weight, degree of branching, comonomer content, or other properties of the polymer. Typical cocatalysts include but are not limited to boron containing activators including boranes or borates.

Other cocatalysts include but are not limited to aluminium alkyls, alkyl aluminium halides and alumoxanes.

Impurities can harm catalysts by reducing their activity. Compounds that react with such impurities and turn them into harmless compounds for catalyst activity are referred to as scavengers by one skilled in the art of polymerization. The scavenger can be the same compound as a cocatalyst and in that case it is generally applied in excess of what is needed to fully activate the catalyst. The scavenger can be used in combination with a sterically hindered hydrocarbon, preferably a sterically hindered phenol, containing a group 15 or 16 heteroatom, (preferably O, N, P and S atoms, more preferably O and N heteroatoms). After the polymerization is complete the reaction mixture is sent to a workup section where the solvent is removed and the polymer is isolated. The work up section may contain a devolatilization unit where the solvent and/or unreacted monomer is removed and recycled. The solvent is typically removed by one or more stripper. One or more extender oils may be added to the reaction mixture before the solvent is removed if oil-extended polymers are to be produced as known in the art. Suitable extender oils include, but are not limited to, petroleum oils, such as aromatic and naphthenic oils; polyalkyl benzene oils; organic acid monoesters, such as alkyl and alkoxyalkyl oleates and stearates; organic acid diesters, such as dialkyl, dialkoxyalkyl, and alkyl aryl phthalates, terephthalates, sebacates, adipates, and glutarates; glycol diesters, such as tri-, tetra- and polyethylene glycol dialkanoates; trialkyl trimellitates; trialkyl, trialkoxyalkyl, alkyl diaryl, and triaryl phosphates; chlorinated paraffin oils; coumarone-indene resins; pine tars; vegetable oils including castor oil, tall oil, rapeseed oil, and soybean oils and including esters and epoxidized derivatives thereof.

After removal of the solvent solid polymer particles (crumbs) are obtained which may be used for the treatment with superheated steam for reducing the volatile content according to the process of the present disclosure. Alternatively, polymer particles obtained from compressed crumbs (bales) or sheets may be used. Preferably, EPDM particles that have been extruded and cut into pellets are used for the process according to the present disclosure for providing EPDM polymers with low volatile content.

In one aspect there is provided a polymer composition comprising at least 95% by weight, or at least 99% by weight, of at least one EDPM polymer wherein the polymer composition has a volatile content of ENB of less than 1 .5 ppm or less than 0.95 ppm or less than 0.60 ppm, and, optionally, a volatile content of VNB of from 0.01 to 0.90 ppm or from 0.03 to 0.5 ppm. Since the process according to the present disclosure only change the volatile content of the polymer but not its composition or properties, the EPDM polymer of the polymer composition is as described above. In one embodiment of the present disclosure the polymer composition has a combined volatile content of ENB and VNB of less than 1.5 ppm or less than 0.95 ppm or less than 0.60 ppm, wherein the minimum content of VNB is 0.01 ppm or 0.03 ppm. Preferably, the polymer composition is in the shape of a pellet, as described above. In one embodiment of the present disclosure the EPDM polymer is oil-extended and the EPDM polymer and contains one or more extender oil. Preferably, the weight ratio of extender oil to EPDM polymer of an oil-extended polymer composition is from 1 :1 to 1 :20. The EPDM compositions are typically provided as pellets as described above or as bales. Such bales typically have a length of at least 30 cm, a width of at least 20 cm and a height of at least 10 cm. The polymer composition may be used for making a curable rubber composition. Typically, the polymer composition is combined with one or more additive, typically a curing agent, to provide a curable rubber composition. Rubber additives and auxiliaries as known in the art may be added to the curable composition. The curable composition may be cured to produce a rubber article. The rubber compositions typically are prepared by blending the ingredients in a kneader or on a mill. Such compounds typically contain from 10 to 95% by weight of rubber and the remainder includes fillers, curatives, processing additives, such as processing oil and other additives tailored to the article to be produced by subjecting the rubber compound to curing and shaping. To increase the content of bio-based materials of rubber compounds and to reduce the CO2 footprint of articles made from rubber compounds, ingredients of biobased sources or other sustainable sources may be used, as described, for example, in Martin van Duin and Philip Hough, “Green EPDM Compounds”, Kautschuk Gummi Kunststoffe, 01-2, 2018, pages 26-37 and in Martin van Duin et al in Chapter 5, Lightweight and Sustainable Materials for Automotive Applications, CRC Press, 2017. For example, recovered carbon black (rCB) may be used instead of conventional carbon black filler. Recovered carbon black may be obtained, for example, from recycling of scrap tire, roofing membrane scrap, conveyor belt scrap or hose scrap, may be used. Silica-based fillers obtained from rice husk ash may be used to replace conventional silica fillers. Instead of fossilbased mineral processing oils sustainable oils from recycled oils, for example from automotive motor oil recycling, may be used as processing oils. Plant-based oils may be used as processing oils also, for example corn oil, coconut oil, linseed oil, rapeseed oil, soybean oil or vegetable oil.

The rubber compositions are curable and can be cured to provided vulcanized rubber compounds or “vulcanizates”. Curing agents as known in the art may be used. Suitable curing (vulcanizing) agents include but are not limited to sulfur, sulfur chloride, sulfur dichloride, 4,4'- dithiodimorpholine, morpholine disulfide; alkylphenol disulfide, tetramethylthiuram disulfide (TMTD), tertaethylthiuram disulfide (TETD), selenium dimethyldithiocarbamate, and organic peroxides. Organic peroxides include but are not limited to dicumyl peroxide (DCP), 2,5-di(t- butylperoxy)-2,5-dimethyl-hexane (DTBPH), di(t-butylperoxyisopropyl)benzene (DTBPIB), 2,5- di(benzoylperoxy)-2,5-dimethylhexane, 2,5-(t-butylperoxy)-2,5-dimethyl-3-hexyne (DTBPHY), di- t-butyl-peroxide and di-t-butylperoxide-3,3,5-trimethylcyclohexane (DTBTCH) or mixtures of these peroxides. Sulfur or a sulfur-containing curing agent is preferably used in an amount of 0.1 to 10 phr. Organic peroxide-based curing agents may be used in an amount from 0.1 to 15 phr, preferably from 0.5 to 5 phr. Sulfur may be used in combination with one or more vulcanization accelerators and activators. Peroxide-based curing agents may be used in combination with one or more coagents. Peroxide-based curing agents may also be used in combination with sulfur or sulfur-based curing agents. Other curing agents include resole or resole-based curing agents.

Fillers

Typically, fillers may be used in an amount of 20 to 500 phr. Fillers as known in the art may be used including carbon black, silica, calcium carbonate, talcum, and clay. The fillers may be surface treated, for example with silanes. Combinations of two or more of such fillers may be used. Preferably, the filler comprises carbon black and/or silanized silica. Further fillers may include one or more rubber other than the copolymer according to the present disclosure. Preferably, fillers from a sustainable source or obtained from a plant-based material, for example lignin-based materials.

Other rubber additives (rubber auxiliaries)

Other rubber additives include those commonly used in the art of rubber compounding. Examples include but are not limited to antioxidants (e.g., hindered phenolics such as commercially available under the trade designation IRGANOX 1010 or IRGANOX 1076 from BASF); phosphites (for example those commercially available under the trade designation IRGAFOS 168), desiccants (e.g. calcium oxide), tackifiers (e.g. polybutenes, terpene resins, aliphatic and aromatic hydrocarbon resins, alkali metal and glycerol stearates, and hydrogenated rosins and the like), bonding agents, heat stabilizers; anti-blocking agents; release agents; anti-static agents pigments; colorants; dyes, processing aids (e.g. factice, fatty acids, stearates, poly-or di-ethylene glycols), antioxidants, heat stabilisers (e.g. poly-2, 2, 4-trimethyl-1 ,2-dihydroquinoline or zinc 2- mercaptobenzimidazole), UV stabilisers, anti-ozonants, blowing agents and mould releasing agents, partitioning agents or processing aids like talc or metal salts, such as e.g. zinc stearate, magnesium stearate or calcium stearate and plasticizers, plasticizer lubricating oils, paraffin, liquid paraffin, petroleum asphalt, low molecular weight polyisobutylene or polybutylene, liquid EPDM or EPM, coal tar pitch, castor oil, linseed oil, beeswax, atactic polypropylene and cumarone indene resin. Plasticizers may be used typically in amounts from 20 to 250 phr.

Articles

For making articles the rubber compounds are subjected to curing and shaping. Curing (also referred to as “vulcanization”) may take place before, during or after shaping. Articles made by using the EPDM polymer according to the present disclosure contain the polymer in cured form, i.e., the polymer is cross-linked either with itself or with other cross-linkable ingredients of the composition used to make the article, for example other curable rubbers. For making articles the rubber compositions may be subjected to one or more curing and shaping processes including, but not limited to, extrusion molding, compression molding, injection molding, foaming, extrusion blow-molding, injection blow-molding, ISBM (Injection Stretched Blow-Molding) and combinations thereof. Typical articles include, but are not limited to, foams, sponges, hoses, belts, seals, engine mounts, roofing material or gaskets. The EPDM polymers of the present disclosure may be used to make layers of layered articles, for example as external or internal layer. Examples of layered materials include hoses, including garden hoses, coolant hoses and hoses for under-the-hood applications and belts including, but are not limited to, conveyor belts, escalator belts and engine belts. The oil-extended ethylene-copolymers of the present disclosure may be used to reduce noise or as vibration-damping materials, for example as engine mounts or in other applications. The EPDM polymers according to the present disclosure may be used as sealing materials or for making seals. Seals include solid seals. A solid seal means the material is not foamed and contrary to a foamed material does not contain a cellular or sponge-like structure. Examples of solid seals include seals to make articles airtight, watertight or to reduce vibrations. Examples include O-rings, flanges for openings, for example in washing machines and other devices. The EPDM polymers according to the present disclosure, may also be used for making foamed articles including sponge-like seals or foamed seals.

The EPDM polymers of the present disclosure may be combined with other polymers to make composite materials, or blends or multi-layer articles. Such polymeric resins include, for example, polyethylene, polyethylene copolymers such as ethylene maleic anhydride and the like, polypropylene, polystyrene, polybutadiene, polyvinylchloride, ethylene-vinyl acetate copolymer (EVA), polyesters such as polyethylene terephthalate (PET), polyhydroxyalkanoate (PHA), high impact polystyrene (HIPS), and acrylonitrile butadiene styrene (ABS), polyurethane, elastomers such as polysulfide rubber, ethylene propylene rubber (EPM), EPDM polymers other than the polymers according to the present disclosure, poly(ethylene-methyl acrylate), polyethyleneacrylate), vinyl silicone rubber (VMQ), fluorosilicone (FVMQ), nitrile rubber (NBR), acrylonitrile- butadiene-styrene (ABS), styrene butadiene rubber (SBR), styrene-butadiene-styrene block copolymers (SBS), styrene-ethylene-butylene-styrene triblock copolymer (SEBS), polybutadiene rubber (BR), styrene-isoprene-styrene block copolymers (SIS), partially hydrogenated acrylonitrile butadiene (HNBR), natural rubber (NR), synthetic polyisoprene rubber (IR), neoprene rubber (CR), polychloropropene, bromobutyl rubber, chlorobutyl rubber, chlorinated poly(ethylene), vinylidene fluoride copolymers (CFM), silicone rubber, vinyl silicone rubber, chlorosulfonated poly(ethylene), fluoroelastomer, elastomeric polyolefins, such as ethylene C3- C12 alpha olefin copolymers, and combinations thereof. In a particular embodiment of the present disclosure the copolymers may be used to make thermoplastic vulcanizates (TPVs). TPVs comprise finely divided rubber particles dispersed within a thermoplastic matrix. Advantageously, the rubber particles are cross-linked to promote elasticity. The dispersed rubber phase is referred to also as the discontinuous phase and the thermoplastic phase as continuous phase. TPV’s have the benefit of the elastomeric properties provided by the rubber with the processability of thermoplastics. TPVs are prepared by dynamic curing. In dynamic curing the rubber is cured using one or more curing agents within a blend with at least one thermoplastic resin under application of shear force, e.g., while the polymers are undergoing mixing or mastication at some elevated temperature, preferably above the melt temperature of the thermoplastic polymer. Typically, dynamic curing is carried out in an extruder under conditions where the rubber is ground into small particles and is dispersed in the molten thermoplastic and is then subjected to curing and the resulting TPV is extruded from the extruder. Thermoplastic resins typically include polypropylene, polyethylene, and combinations thereof as well as combinations with other thermoplastic resins. Examples of TPV’s and method of producing TPV are described, for example, in international patent application WO2019199486A1 , incorporated herein by reference, in particular to pages 11-15 for selecting thermoplastic polymers and in particular to pages 21-25 for methods of making TPV’s. In one embodiment of the present disclosure, there is provided a composition for making a thermoplastic vulcanizate, TPV, comprising the EPDM polymer according to the present disclosure, a thermoplastic resin, preferably selected from a polypropylene, a polyethylene, or a combination thereof, and a curative.

In another preferred embodiment of the present disclosure there is provided a process for producing a thermoplastic vulcanizate, TPV, comprising blending the EPDM polymer according to the present disclosure, a thermoplastic resin, preferably selected from at least one polypropylene, at least one polyethylene or a combination thereof, and a curative, and subjecting the blend to dynamic curing, preferably in an extruder, wherein, preferably, the EPDM polymer is blended with the thermoplastic resin above the melt temperature of the resin before the curative is added to the blend. Also provided is a thermoplastic vulcanizate, TPV, obtained from this process. The EPDM polymer according to the present disclosure is preferably used in “indoor” application, for example for making articles for use in the passenger cabin of an automotive vehicle, including TPV’s, window seals and door seals.

The present disclosure will now be illustrated further by way of examples, without, however, intending to limit to the disclosure to the examples presented.

Examples and Methods

Methods

Volatile Content of ENB and VNB

The volatile content of ENB and VNB was determined by head space GC-MS. Head space GC- MS measurements were carried out at a measuring temperature of 250°C. Polymer samples (2g) were cut into small pieces of about 1 mm size. The samples were wiped dry with a cloth if they had condensed water on their surface. 4 hours prior to the analysis the samples were conditioned in an oven at 23 ± 2°C and 50 ±10 %rH. For the analysis the samples were placed into a standard headspace vial with a screw-cap. The vial was heated to 150°C for 30 minutes before a defined volume of the headspace gas was taken (Agilent headspace sampler 7697A) and injected into the GO column (Agilent DB-624, at 250°C, 1 ml/min He gas). The quantification was based on a prior calibration with known amounts of VNB and ENB.

Polymer composition:

Fourier transformation infrared spectroscopy (FT-IR) can be used to determine the composition of the copolymers according to ASTM D3900 (revision date 2017) for the C2/C3 ratio and D6047 (revision date 2017) for the diene content on pressed polymer films.

Branching:

AS is a measure for the presence of long-chain branches in the polymer structure. The lower the value of AS the more long-chain branches are present in the polymer. The method is described in H.C. Booij, in Kautschuk + Gummi Kunststoffe, Vol. 44, No. 2, pages 128-130,1991.

Molecular weight:

The molecular weights (weight-average molecular weight (Mw), number-averaged molecular weight (Mn) and Mz vaules) and the molecular weight distribution (MWD) can be determined by gel permeation size exclusion chromatography (GPC) using a Polymer Char GPC-IR from Polymer Characterization S.A, Valencia, Spain. The Size Exclusion Chromatograph is equipped with an online viscometer (Polymer CharV-400 viscometer), an online infrared detector (IR5 MCT), with 3 AGILENT PL OLEXIS columns (7.5 x 300 mm) and a Polymer Char autosampler. Universal calibration of the system is performed with polyethylene (PE) standards.

The polymer samples are weighed (in the concentration range of 0.3-1 .3 mg/ml) into the vials of the PolymerChar autosampler. In the autosampler the vials are filled automatically with solvent (1 ,2,4-tri-chlorobenzene stabilized with 1 g/l di-tertbutylparacresol (DBPC)). The samples are kept in the high temperature oven (160°C) for 4 hrs. After this dissolution time, the samples are automatically filtered by an in-line filter before being injected onto the columns. The chromatograph system is operated at 160°C. The flow rate of the 1 ,2,4-trichlorobenzene eluent is 1.0 mL/min.

Mooney viscosity:

The Mooney viscosity of the copolymer samples can be measured according to ISO 289, revision date 2015. The measuring conditions are ML (1+4) @ 125°C.

Examples

Examples 1-7 (comparative)

Commercial EPDM polymers from various suppliers were analysed for their volatile content (ENB and VNB content) by head space GC-MS. The results are shown in table 1. All samples had a noticeable odour that is typical for norbornenes.

* from Kumho Polychemical Co ltd; ** from Mitsui Chemicals, *** from Dow Chemical Inc. Examples 8 and 9 (VOC removal by wet finishing; comparative)

Example 8

An EPDM polymer (Mooney viscosity ML1+4, 125°C of 80 MU, ethylene content of 48wt%, ENB content 4.5wt% and a VNB content of less than 1 wt%) was produced by solution polymerization as described in WO 2005/090418 and isolated by wet stripping. For the wet stripping process the reaction mixture was fed into a first stripper where polymer crumbs were formed and most of the low boiling components and a major portion of the solvent were evaporated. The polymer crumbs were fed through a series of additional steam-strippers for further removal of volatile organic components. Then the crumbs were separated from water by mechanical dewatering, an extrusion expander process and subsequently by a crumb drier. The time on the crumb drier was 15 minutes. Two samples were measured for their VOC content and had an ENB content of 8.97 / 8.87 ppm and a VNB content of 1.27 / 1.37 ppm, respectively. The samples had the distinct odour of norbornenes.

Example 9

Example 8 was repeated except that the steam feed and the temperature in the strippers was increased, which reduced the size of the crumbs. The throughput was lowered to 47% compared to that of example 8. The time on the crumb drier was increased to 30 minutes. In the drier the size of the crumbs was decreased. Two samples were measured for their volatile content. A VOC content of 1.46 / 1.34 ppm ENB and 0.94 / 0.92 ppm VNB was detected. Only a faint odour of norbornenes was noticed.

Example 10 (VOC reduction by superheated steam)

The polymer obtained in example 8 was pelletized in an extruder to form cylindrical pellets of approximately 10 mm in diameter and 5 mm in height. The typical odour of norbornenes was noticed. The pellets were placed into a 10-I glass reactor which was heated by an external heating jacket to above 100°C. Around 200 g polymer pellets were placed into the vessel to give a loose packing. Steam was generated in a steam boiler at a pressure of 3 bar and was routed from the boiler via an insulated pipe to the bottom of the glass reactor stripping vessel to generate a gentle flow of steam through the pellets while the pellets were stirred a 60 rpm with a stirrer with a PTFE- lined shaft and metal paddles. The steam was reduced from 3 bar to ambient pressure (1 bar) via a relief nozzle between boiler and reactor to ensure the steam entering the reactor was superheated. By using the Mollier-diagram for steam for an isenthalpic process it was found that the expanded steam was superheated with a temperature of 124°C at ambient pressure. The dryness of the steam was calculated as 8.25%. The pellets were stripped with the superheated steam for 2 hours. Samples were taken every 30 minutes and subjected to analysis for their VOC content by head space GC-MS.

Example 11

Example 10 was repeated except that superheated steam was used that was generated by a pressure drop of 4 bar to ambient pressure. According to the Mollier diagram the steam was superheated with a temperature of 131 °C and had a dryness of 9.82%.

The reduction of volatile content (sum of volatile ENB and VNB) with stripping time in examples 10 and 11 is shown in table 2. The samples with time = 0 refer to the untreated polymer pellets.

Table 2

An EPDM polymer with a combined volatile content of ENB and VNB of less than 1 ppm typically has no noticeable norbornene odour. As can be seen from table 2 this status was reached in example 10 within 1 hour and in example 11 within less than 30 minutes. Example 12

Example 10 was repeated except that the superheated steam was generated by a pressure drop of from 4.5 bar to ambient pressure. After the pressure drop the superheated steam had a temperature of 136°C and a calculated dryness 10.52%. Granules with a combined volatile content of ENB and VNB of about 5 ppm were used. The volatile content was reduced by about 50% within 15 minutes, which is a faster rate than observed for examples 10 and 11 and indicates that superheated steam with increasing temperatures accelerates the removal of volatile ENB and VNB.

Example 13 (Removal of volatile ENB and VNB from polymer crumbs with superheated steam)

Polymer crumbs were produced as in example 8 but instead of subjecting them to drying on the drier belt the crumbs were subjected to treatment with superheated steam. The experimental set up of example 10 was used. The superheated steam was generated as described in example 8 except that the pressure drop was from 4.5 bar to ambient pressure. The content of volatile VNB and ENB could be reduced from 59.6 / 52.9 ppm ENB and 5.0 / 4.0 ppm VNB before stripping to less than 5 ppm at 30 minutes, and to 1 .08 /0.96 ppm ENB and 0.09 / 0.09 ppm VNB, respectively, within 60 minutes.

Claims

Claims

1. A process for providing an EPDM polymer with a reduced content of volatile ENB said process comprises

(i) providing an EPDM polymer comprising from 1 % to 20 % by weight of units derived from ENB, based on the total weight of the EPDM polymer,

(ii) treating the EPDM polymer of step (i) with superheated steam to reduce the volatile ENB content of the EPDM polymer;

(iii) ceasing the treatment with superheated steam,

(iv) optionally, cooling the polymer to room temperature.

2. The process of claim 1 further comprising a step (ia) which is carried out simultaneously with or after step (i) and simultaneously with or before step (ii), where step (ia) comprises heating the EPDM polymer to a temperature above the boiling point of water at a present pressure, wherein the present pressure is selected from ambient pressure, pressure above ambient pressure and pressure below ambient pressure.

3. The process of claim 1 wherein the EPDM polymer of step (I) has from 0.2% to 10% by weight of units derived from VNB, based on the total weight of the EPDM polymer.

4. The process of claim 1 wherein the EPDM polymer in step (i) is shaped into a pellet or a plurality of pellets.

5. The process of claim 1 further comprising a step (v) comprising shaping the EPDM polymer into a pellet or a plurality of pellets and wherein step (v) is carried out after step (ii), or after step (iii) or after step (iv).

6. The process of claim 1 wherein the EPDM polymer with reduced content of volatile ENB has a volatile content of ENB of less than 1.5 ppm or less than 1.0 ppm or less than 0.60 ppm as determined by head space GC-MS according to the measuring method as described in the experimental section.

7. The process of claim 1 wherein the EPDM polymer with reduced content of volatile ENB has a combined volatile content of ENB and VNB of less than 1.0 ppm and a content of volatile VNB of from 0.1 to 0.90 ppm or from 0.2 to 0.5 ppm as determined by head space GC-MS according to the measuring method as described in the experimental section.

8. The process of claim 1 wherein the EPDM polymer with reduced content of volatile ENB has an Mw of at least 50 kg/mol or at least 125 kg/mol.

9. The process of claim 1 wherein the EPDM polymer with reduced content of volatile ENB has a Mooney viscosity, ML 1+4 at 125°C of from 20 and up to 120.

10. The process of claim 1 wherein the EPDM polymer with reduced content of volatile ENB has a branching index AS of from 2 to 20°.

11 . A polymer composition comprising at least 95% by weight, or at least 99% by weight, of an EDPM polymer having units derived from 1 to 20 % by weight of ENB and, optionally, from 0.2 to 10 % by weight of VNB, wherein the polymer composition has a volatile content of ENB of less than 1.5 ppm or less than 1 .0 ppm or less than 0.60 ppm.

12. The polymer composition of claim 12 wherein the polymer composition has a volatile content of VNB of from 0.01 to 1.9 ppm or from 0.1 to 0.5 ppm.

13. The polymer composition of claim 12 wherein the polymer composition is a pellet.

14. A process of making a TPV comprising (i) extruding a blend produced by combining at least one polymer composition of claims 11-13 with a thermoplastic polymer, preferably a polypropylene polymer, and (ii) extruding the resulting mixture in the presence of at least one curing agent to produce a TPV, wherein the blend is produced prior or during the extrusion.

15. An article obtained with the polymer composition of any one of claims 11-13.