Method and system for feeding liquid organic peroxide to polymer melt processing equipment

Abstract

The present disclosure relates to a method and system for feeding liquid organic peroxides to polymer melt processing equipment. The feeding method comprises transporting at least one liquid organic peroxide (13) with an inert liquid cooling carrier (4) in the form of an undissolved mixture from a temperature controlled section (3) to the polymer melt processing equipment.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a method for feeding at least one liquid organic peroxide to a polymer melt processing. The present disclosure also relates to a corresponding system. BACKGROUND

[0002] It is known to use organic peroxides, typically liquid organic peroxides, for rheological modification of polyolefins, including "vis-breaking" and cross-linking thereof. Cross-linking is typically applied, for example, to polyethylene.

[0003] A known process for vis-breaking polyolefins is extrusion in the presence of an organic peroxide compound at temperatures of about 190°C to 260°C. An example of this process is described in document AU 5141785 A.

[0004] However, due to the organic nature of pure organic peroxides, which are very unstable, volatile and hazardous species, there is a high risk of fire or explosion in case of uncontrolled temperature increase, and therefore special handling precautions are required. This nature can not comply with the rules for transport and storage and / or the special efforts required for safe handling and storage, making the use of pure organic peroxides very expensive and technically complex. Furthermore, the use of pure organic peroxides in polymer melt processing, such as for example extrusion processes carried out at high temperatures, is even more dangerous.

[0005] Therefore, the safe handling and transport of liquid organic peroxides is a major issue, and the use of pure liquid organic peroxides in polymer melt processing, and at least to some extent the use of some diluted liquid organic peroxides, can be problematic.

[0006] To solve the problems related to storage and transport, liquid organic peroxides are diluted with mineral oil. By diluting the organic peroxides, a less restricted peroxide product safety class can be obtained. Furthermore, the dispersion of the organic peroxides in the polymer, for example polyolefins, can be facilitated by diluting the organic peroxides in mineral oil. However, mineral oil can cause some undesirable side effects affecting the properties of the polymer. For example, currently available mineral oil diluted organic peroxides have no safety issues, allow for greater storage capacity relative to those available pure organic peroxides, but introduce a solvent into the polymer, which can interfere with the polymer conversion into the final polymer product, and can lead to additional degradation of by-products during the peroxide reaction in the extruder. These degradations and by-products can lead to the production of high volatile organic compounds (VOCs) and undesirable odors from the polymer and the final polymer product.

[0007] A method for changing the rheology of a polymer is described in US 2018 / 0030163 Al. The method comprises extruding a molten polymer and a composition comprising at least one organic peroxide and water in the form of an emulsion, and removing volatile compounds from the molten polymer. The volatile compounds include volatile organic compounds and water. However, US 2018 / 0030163 Al ignores the way the organic peroxide is handled upstream of the extruder, in particular the way the organic peroxide is transported from a storage of the organic peroxide to the extruder.

[0008] More generally, for transporting liquid organic peroxides from a first location (for example, a storage location of the organic peroxide) to a second location (for example, a location of use of the organic peroxide), it is generally known to transport these liquids through a pipe equipped with temperature control means. For example, the pipe can be arranged within a temperature-controlled enclosure for its entire extension. Such an enclosure must be designed to maintain the pipe at the desired controlled temperature from the first location to the second location, which requires additional equipment and associated costs. In addition to arranging the entire pipe within a temperature-controlled enclosure, another example known in the art of transporting organic peroxides is the use of a jacketed pipe. Another example is to provide the pipe with external heat tracing means. Regardless of the type of temperature control means known, in any case, these means are not suitable for covering the typical long distances of an industrial site where liquid organic peroxides are used as starting materials or additives in a manufacturing process.

[0009] In all these examples of prior art, specific equipment must be provided to ensure that the pipe used to transport the liquid organic peroxide is maintained within the temperature range required for the safe transport of these liquids.

[0010] Therefore, there is still a need to develop a method and a system for the safe transport of liquid organic peroxides at an industrial site, including where the organic peroxide is intended for use in a polymer melt processing or equipment, without affecting or altering the final properties of the polymer subjected to melt processing. SUMMARY

[0011] Applicants have surprisingly found that by transporting liquid organic peroxides in the form of an undissolved mixture with an inert cooling carrier, i.e. the liquid organic peroxide is suspended in the inert cooling carrier, which is an aqueous liquid at ambient temperature and volatile under melt processing conditions, it is possible to safely transport the organic peroxide from any location, such as a temporary or long-term storage location, to a polymer melt processing equipment, without the need to use equipment or devices specifically designed to control the temperature of the liquid organic peroxide, but simply by means of any ordinary conduit, pipe or hollow body suitable for transporting liquids.

[0012] This finding also allows to limit the use of temperature control components, such as housings, containers and devices configured for this purpose, to the storage of organic peroxides only, for example in the form of dedicated, temperature controlled containers, thus reducing the energy consumption.

[0013] Furthermore, regardless of the distance to be covered by the liquid organic peroxide to be applied to the polymer melt processing equipment, for example the distance involved by the industrial plants for the polymer melt processing, the delivery of the liquid organic peroxide in the form of an undissolved mixture with an inert cooling carrier as defined above will result in a safe delivery of the liquid organic peroxide. Thus, this delivery is simple and suitable for plants of any scale, requiring only limited investments.

[0014] The Applicant found that the same technical effect can also be obtained when delivering a plurality of liquid organic peroxides to the polymer melt processing equipment.

[0015] According to a first aspect of the present disclosure, the present disclosure relates to a method for feeding a liquid organic peroxide to a polymer melt processing equipment, the method comprising mixing at least one liquid organic peroxide and an inert cooling carrier in a mixing section arranged in a temperature controlled section, the mixing being performed without dissolving the at least one liquid organic peroxide in the inert cooling carrier. The method further comprises delivering the at least one liquid organic peroxide in the form of an undissolved mixture with the inert cooling carrier from the temperature controlled section to the polymer melt processing equipment arranged outside the temperature controlled section. The inert cooling carrier comprises an aqueous liquid at ambient temperature, which is volatile under melt processing conditions. For example, the temperature controlled section can comprise a reservoir of one or more liquid organic peroxides of any type, such as for example a temporary or long-term reservoir of one or more liquid organic peroxides.

[0016] The inert cooling carrier can be any aqueous carrier inert with respect to the at least one organic peroxide, which is liquid at ambient temperature and pressure, and which is capable of maintaining the temperature of the at least one organic peroxide within a temperature range required for safe delivery of the peroxide, such as for example 5°C to 40°C, depending on the liquid organic peroxide. For example, when a combination of liquid organic peroxides is used, the inert cooling carrier can be an aqueous liquid immiscible with the liquid organic peroxide or with all liquid organic peroxides. According to the present disclosure, the inert cooling carrier does not act as a solvent, i.e. the inert cooling carrier does not dissolve the at least one liquid organic peroxide, but rather keeps the at least one liquid organic peroxide in a suspended state. According to one or more embodiments, the at least one organic peroxide and the inert cooling carrier can be delivered to the polymer melt processing equipment in an unstable mixture.

[0017] Such a method defined in the first aspect of the disclosure is effective for the safe delivery of any liquid organic peroxide and is suitable for the integration of any temperature controlled reservoir or storage and any polymer melt processing equipment into a single, simplified device without the need for specially designed enclosures, equipment or piping to safely feed the liquid organic peroxide to the polymer melt processing equipment. This integration can be successfully implemented with reduced energy consumption relative to the methods of the prior art and can also be successfully implemented in the case of high production polymer melt processing equipment or devices such as, for example, high production extrusion devices.

[0018] According to one or more embodiments, the method comprises delivering one or more liquid organic peroxides with an inert cooling carrier in the form of an undissolved mixture.

[0019] The liquid organic peroxide can be any liquid form of organic peroxide.

[0020] According to one or more embodiments, the at least one liquid organic peroxide can comprise at least one dialkyl peroxide such as, for example, 2,5-dimethyl-2,5-di(tert- butylperoxy)hexane, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane-3, di(tert-butylperoxy- isopropyl)-benzene, dicumyl peroxide, 3,6,9-triethyl-3,6,9-trimethyl-l,4,7-triacetone, 3,3,5,7,7-pentamethyl-l,2,4-trioxepane and combinations thereof.

[0021] According to one or more embodiments, the inert cooling carrier is volatile at a temperature of 5°C to 80°C under negative pressure, for example at a pressure of 1000 mbar(a) to 800 mbar(a), for example between 800 mbar(a) and 600 mbar(a).

[0022] According to the disclosure, the inert cooling carrier comprises an aqueous cooling carrier. For example, the cooling carrier can be water. The water can be distilled water or deionized water (e.g., demineralized water), for example containing less than 2%, less than 1%, less than 0.5%, less than 0.1% or no dissolved compounds, such as salts. When water is distilled, the water can not only contain this level or lower content of salts, but also less than 2%, less than 1%, less than 0.5%, less than 0.1% of organic compounds or no organic compounds.

[0023] By using water as a carrier, the polymer can be contacted with the undissolved mixture of one or more liquid organic peroxides and the aqueous carrier delivered under melt processing conditions and the aqueous carrier is then easily removed.

[0024] Additionally, any volatile compounds can also be removed from the molten polymer. Rheological modification of the polymer can also be performed in the melt processing equipment whenever needed. Removal of any volatile compounds can reduce the concentration of degradation and by-products in the polymer, thereby reducing VOCs, reducing odor concentration in the polymer, and reducing color formation. Furthermore, the aqueous cooling carrier or water as carrier can deactivate any active catalyst sites remaining in the polymer. Thus, polymer deactivation can be accomplished in the melt processing equipment without the need for a specific deactivation device. Moreover, by providing sufficient mixing in the melt processing equipment, deactivation can be uniform and can be obtained in an efficient manner.

[0025] According to one or more embodiments, the method comprises feeding the aqueous cooling carrier or water to be mixed with the at least one liquid organic peroxide at a predetermined temperature. For example, the water can be fed at a temperature of 5 °C to 40 °C.

[0026] According to one or more embodiments, the melt processing equipment comprises an extruder or a kneader. For example, the melt processing equipment can comprise a single screw or a twin screw extruder, alone or in combination. According to one or more embodiments, the method can comprise feeding the mixture of one or more liquid organic peroxides and water into a hopper of the extruder, regardless of the type of extruder. Alternatively, the mixture of peroxide and cooling carrier can be injected into the processing unit of the plastics processing equipment immediately downstream of the hopper of the processing equipment, i.e. at a point where the polymer fed through the hopper is still in a solid state.

[0027] According to one or more embodiments, the method further comprises storing the at least one liquid organic peroxide in a temperature-controlled section. In this way, the method allows direct feeding of the at least one liquid organic peroxide from the location where the at least one liquid organic peroxide is stored.

[0028] According to the present disclosure, the method further comprises mixing (e.g. mechanically mixing) the at least one liquid organic peroxide and the inert cooling carrier in a mixing section arranged in the temperature-controlled section. According to one or more embodiments, a single temperature-controlled section can be sufficient to control the temperature of both storage and mixing. For example, a common temperature-controlled section can safely accommodate a reservoir or storage for storing the at least one liquid organic peroxide and a mixer for mixing the at least one liquid organic peroxide with the inert cooling carrier.

[0029] According to one or more embodiments, the method further comprises feeding the inert cooling carrier to the mixing section, for example in a continuous manner. According to one or more embodiments, the method further comprises feeding the inert cooling carrier to the mixing section at a predetermined flow rate, which can be for example constant or variable. By way of example, the predetermined flow rate can be from 1000 ppm to 5000 ppm, from 1200 ppm to 4000 ppm, from 1500 ppm to 3000 ppm, from 2000 ppm to 3000 ppm, based on the production volume of the plastic processing equipment (wherein, in the present disclosure and in the following claims, ppm means mg / kg, thus ppm by weight). For example, the flow rate of the inert cooling carrier can be at least twice the flow rate of the liquid organic peroxide. For example, the flow rate of the inert cooling carrier can be three times higher than the flow rate of the liquid organic peroxide. The method can further comprise adjusting the flow rate of the inert cooling carrier as a function of the flow rate of the liquid organic peroxide, which can be constant or variable, as needed. The method can further comprise adjusting the flow rate of the liquid organic peroxide and the constant flow rate of the inert cooling carrier, as needed, for example as a function of the way the polymer melt processing is carried out and the flow rate of the polymer feed.

[0030] According to one or more embodiments, the method further comprises pumping at least one liquid organic peroxide from a reservoir to the mixing section at a predetermined flow rate, which can be for example constant or variable. By way of example, the predetermined flow rate can be from 10 ppm to 6000 ppm, from 30 ppm to 6000 ppm, from 50 ppm to 6000 ppm, from 50 ppm to 5000 ppm, from 100 ppm to 4000 ppm, from 200 ppm to 2000 ppm, from 300 ppm to 800 ppm, based on the production volume of the plastic processing equipment. The method can further comprise adjusting the predetermined flow rate of the at least one liquid organic peroxide, as needed, for example as a function of the way the polymer melt processing is carried out and the flow rate of the polymer feed.

[0031] According to one or more embodiments, the polymer comprises or consists of a polyolefin.

[0032] According to one or more embodiments, the polyolefin can be selected, for example, from homopolymers and copolymers of olefins, the olefin monomers having, for example, from 2 to 8 carbon atoms.

[0033] According to one or more embodiments, the polyolefin can be selected from the group comprising polypropylene homopolymers, polyethylene homopolymers, copolymers comprising propylene, copolymers comprising ethylene, and combinations thereof. For example, the polyolefin can be selected from the group consisting of polypropylene homopolymers, propylene copolymers, polyethylene homopolymers, and ethylene copolymers.

[0034] According to one or more embodiments, polyethylenes such as linear low density polyethylene (LLDPE), low density polyethylene (LDPE), high density polyethylene (HDPE), and ethylene-vinyl acetate (EVA) and polyolefin elastomers (POE) can be used. According to one or more embodiments, polyethylene homopolymers and copolymers having a density in the range of 0.88 g / cm3 3 to 0.96 g / cm3 3 may be used, for example. The polyethylene homopolymers and copolymers can be manufactured by any known method.

[0035] According to one or more embodiments, polypropylenes including homopolymers, random copolymers, block copolymers, and terpolymers of propylene can be used. Copolymers of propylene can include copolymers of propylene with other olefins such as ethylene, 1-butene, 2-butene, and pentene isomers, for example copolymers of propylene with ethylene. Terpolymers of propylene can include copolymers of propylene with ethylene and another olefin. Random copolymers, also known as statistical copolymers, are polymers in which propylene and comonomer are randomly distributed in the polymer chain in proportions corresponding to the feed ratio of propylene to the comonomer. Block copolymers are made from segments consisting of propylene homopolymers and segments consisting of random copolymers of, for example, propylene and ethylene. The homopolymers, random copolymers, and block copolymers can be manufactured by any known method.

[0036] According to a second aspect of the disclosure, the disclosure relates to a method for melt processing a molten polymer, the method comprising the method of feeding at least one liquid organic peroxide to a polymer melt processing equipment as defined in any one of the embodiments disclosed herein. The method for melt processing a molten polymer further comprises melt processing the molten polymer in the presence of the at least one organic peroxide and the inert cooling carrier in the polymer melt processing equipment and removing the inert cooling carrier from the molten polymer. The melt processing can include extruding the polymer and optionally rheology modifying the polymer, for example including polymer degradation and / or crosslinking. The method for melt processing can further include removing any additional volatile compounds from the molten polymer in addition to removing the inert cooling carrier.

[0037] According to one or more embodiments, the polymer melt processing equipment can include an extruder.

[0038] For example, the removed volatile compounds can include volatile organic compounds in addition to the aqueous cooling carrier or water.

[0039] According to one or more embodiments, the melt processing of the molten polymer described above can include extruding the molten polymer and the undissolved mixture of the at least one organic peroxide and the inert cooling carrier in the presence of the at least one organic peroxide and the inert cooling carrier in a polymer melt processing equipment. According to one or more embodiments, the extruding of the molten polymer and the undissolved mixture can be performed by extruding a polymer, which can be, for example, in the form of an initial powder or pellets, adding the mixture described above to the polymer, and melt extruding the polymer in the presence of the mixture. For example, the mixture can be added to the polymer prior to or during the extrusion of the polymer. According to one or more embodiments, the mixture can be added to the polymer in such a way that the amount of the at least one organic peroxide relative to the amount of the polymer reaches a predetermined value. For example, the mixture can be added to the polymer so that the amount of the at least one peroxide added to the polymer relative to the amount of the polymer is in the range of 100 ppm to 6000 ppm, 200 ppm to 5000 ppm, 300 ppm to 4000 ppm. According to one or more embodiments, the mixture can be added to the polymer so that the amount of the at least one peroxide added to the polymer relative to the amount of the polymer is in the range of 100 ppm to 3000 ppm.

[0040] The extrusion can be performed in an extruder or any other melt processing device. In both cases, the extrusion is performed under extrusion conditions. Under extrusion conditions, the inert cooling carrier can be in the form of a vapor and, when removed, for example, by venting the extruder, can extract the undesired deactivated species and degradation products from the molten polymer in an enhanced manner. The enhanced degassing of the undesired degradation products and byproducts obtained by removing the vapor under extrusion conditions further reduces the VOC and odor concentration. Thus, improved polymer degassing can be obtained during the melt processing of the polymer. Therefore, the method according to one or more embodiments of the present disclosure not only results in safe and easy delivery of the at least one liquid organic peroxide and melt processing of the polymer by contacting the at least one organic peroxide with the molten polymer under extrusion conditions, but also results in efficient extraction of the inert cooling carrier from the molten polymer and extraction of any deactivated species and degradation products.

[0041] According to one or more embodiments, the extrusion can be performed in the presence of one or more polymer additives. Exemplary additives can include, for example, fillers, antioxidants, fungicides, bactericides, reinforcing agents, antistatic agents, heat stabilizers, ultraviolet stabilizers, flow enhancers, colorants, and other additives or processing aids known to those skilled in the art.

[0042] According to one or more embodiments, the extrusion can be carried out in an extruder under predetermined extrusion conditions suitable for extruding the polymer, such as, for example, at a predetermined extrusion temperature and a predetermined extrusion production rate. In relation to the extruder, unless otherwise specified, in the present description and in the claims below, the exemplary extrusion temperatures and pressures are intended to indicate barrel temperatures and pressures.

[0043] For example, the extrusion can be carried out at an extrusion temperature of 180°C to 260°C, for example 190°C to 250°C, for example 190°C to 240°C.

[0044] According to one or more embodiments, the extrusion conditions can vary along the length of the extruder. For example, the extrusion temperature can be increased or decreased along at least a portion of the extrusion path, which can extend along different extrusion zones.

[0045] Independently or in combination with possible variations in temperature along the length of the extruder, the extrusion pressure can also vary along the length of the extruder. For example, the extrusion conditions can comprise a feed zone pressure of 10 mbar to 50 mbar and a melt compression zone of 30 bar to 120 bar. The remaining zones can have a pressure between the exemplary pressures of the feed zone and the melt compression zone.

[0046] The extrusion conditions can also comprise intense mixing in the extruder. According to one or more embodiments, sufficient mixing can be obtained by varying the screw speed of the extruder in the range of 2 m / s to 6 m / s based on the circumferential speed.

[0047] According to one or more embodiments, the polymer powder or granules and the mixture can be fed individually or in combination into the extruder, which can be, for example, a single-screw or twin-screw extruder.

[0048] When fed in combination, the polymer powder or granules and the mixture can optionally be premixed, for example at a temperature of 30°C to 40°C.

[0049] The polymer powder or granules and the mixture can be fed individually into the extruder at a predetermined feed rate. For example, for a laboratory extruder, the feed rate of the polymer can be set in the range of 2 to 500 kg / h, for an industrial extruder, in the range of 5 t / h to 100 t / h, and the feed rate of the mixture can be adjusted to obtain the final granules with the desired MFR.

[0050] According to one or more embodiments, when fed separately from the polymer, the undissolved mixture can be added to the extruder in a continuous manner or in a discontinuous manner, stepwise or gradually.

[0051] According to one or more embodiments, the temperature of different zones of the extruder can be set at a lower value prior to introduction of the mixture, which can be set in a predetermined exemplary temperature range at a steady state known in the art. For example, the temperature of different zones of the extruder can be set in a temperature range that is at least 10 to 20 °C lower than the corresponding steady state extrusion temperature. However, the mixture can also be introduced after the temperature of different zones of the extruder reaches the steady state temperature range.

[0052] According to one or more embodiments, the mixture feed rate into the extruder can be gradually increased to a predetermined value, which can vary with the desired final MFR of the pellets. The final MFR can be measured by, for example, an online rheometer installed on the die zone of the extruder.

[0053] Prior to increasing the mixture feed rate into the extruder to a steady state value, the temperature of the barrel and die zone can be maintained at the same temperature set prior to introduction of the mixture, or can be further decreased, for example, by 5 °C to 10 °C.

[0054] According to one or more embodiments, the removal is by venting the polymer melt processing equipment. To this end, the polymer melt processing equipment can for example comprise a reduced pressure zone comprising a venting zone.

[0055] According to one or more embodiments, the polymer melt processing equipment comprises an extruder comprising at least one reduced pressure zone comprising a venting zone, for example comprising at least one vent or a plurality of vents. The at least one reduced pressure zone can for example be disposed about two-thirds down the screw of the extruder. The reduced pressure zone allows gases, such as moisture and volatiles, including inert cooling carriers, to escape from the molten polymer through the venting zone, for example through one or more vents provided in the venting zone.

[0056] By using a vented extruder comprising at least one vent, pressure can be released in the at least one reduced pressure zone and any trapped gases can be extracted by vacuum. With such an extruder, the method according to one or more embodiments of the present disclosure provides additional effects that positively impact the performance of the polymer, for example polyolefin. These effects include deactivation of active catalyst sites and improved polymer degassing beyond what would be expected from water and organic peroxide acting alone. Deactivation of active catalyst sites and improved polymer degassing in turn results in a purer polymer containing less amounts of reaction by-products and volatiles, improved organoleptic properties such as odor and taste, and less color formation. Furthermore, water in the composition, when removed through the at least one vent, extracts undesirable deactivated species and degradation products from the molten polymer.

[0057] According to one or more embodiments, the removing is performed by venting the extruder, for example during extrusion. For example, the venting can be performed through at least one vent or vacuum port in the extruder venting zone. According to one or more embodiments, a plurality of vent ports can be defined circumferentially around the barrel and / or longitudinally along a portion of the barrel.

[0058] The vent port can strip the reaction water and undesired deactivated species by a predetermined vacuum (i.e. negative pressure) to ensure the absence of residual water in the polymer.

[0059] According to one or more embodiments, the removing is performed by establishing a predetermined vacuum in the extruder venting zone or a plurality of venting zones. In case of a plurality of venting zones, each venting zone can be provided in a corresponding decompression zone of the extruder comprising a plurality of decompression zones. However, according to one or more embodiments, a plurality of venting zones can be provided in each decompression zone of the extruder.

[0060] According to one or more embodiments, the predetermined vacuum is set from 0 mbar to 800 mbar, for example from 200 mbar to 800 mbar, for example from 300 mbar to 600 mbar, for example from 350 mbar to 550 mbar. According to one or more embodiments, the removing can be performed by setting a predetermined vacuum pressure in the decompression zone of the extruder comprising the venting zone. For example, the decompression zone vacuum pressure can be from 0 mbar to 800 mbar.

[0061] For example, the negative pressure in the venting zone can be maintained by attaching the at least one vent port to a tube leading to a vacuum pump or other known device for generating a vacuum.

[0062] According to one or more embodiments, the polymer melt processed by the method can comprise any of the exemplary polymers defined hereinabove.

[0063] For example, the polymer to be melt processed can be a propylene homopolymer or copolymer. According to one or more embodiments, the propylene homopolymer or copolymer can have an initial MFR measured according to ISO 1133 at 230 °C under a load of 2.16 kg from about 0.2 g / 10 min to about 100 g / 10 min, for example from 0.2 g / 10 min to 50 g / 10 min, for example from 0.2 g / 10 min to 20 g / 10 min, prior to melt processing.

[0064] In the description and claims, if not otherwise indicated, otherwise MFR is the MFR measured according to ISO 1133 at 230 °C under a load of 2.16 kg.

[0065] According to one or more embodiments, the propylene homopolymer or copolymer can have a final MFR that is up to 5000% higher than the initial MFR after melt processing with one or more embodiments of the mixture. According to one or more embodiments, the final MFR can be from 50 g / 10 min to 2000 g / 10 min, such as from 20 g / 10 min to 100 g / 10 min, such as from 5 g / 10 min to 20 g / 10 min.

[0066] According to another aspect of the disclosure disclosed herein, the disclosure relates to a polymer composition obtained by one or more embodiments of the above-mentioned method.

[0067] The polymer composition can be used for the preparation of different product applications, such as for example molding, film and fiber applications. Examples of product applications are injection molded and blow molded products, such as for example injection molded and blow molded products for packaging and automotive applications. Spunbond nonwoven and melt blown fiber applications, such as for example hygiene, medical, automotive and geotextile applications, can also be exemplary applications for the polymer composition.

[0068] According to another aspect of the disclosure, the disclosure relates to the use of distilled or deionized water as an inert cooling carrier for at least one organic peroxide in a polymer melt processing equipment.

[0069] According to one or more embodiments, the water can have one or more properties indicated in any one of the embodiments described above with reference to any method.

[0070] According to another aspect of the disclosure, the disclosure relates to a system for feeding liquid organic peroxide to a polymer melt processing equipment. The system comprises a temperature controlled section comprising a reservoir of at least one organic peroxide and a mixer for mixing the at least one liquid organic peroxide with an inert liquid cooling carrier without dissolving the at least one liquid organic peroxide. The system further comprises a pipe configured to put the mixer in fluid communication with a polymer processing equipment arranged outside the temperature controlled section. The pipe is not provided with any cooling means, such as for example a cooling jacket, a double wall for circulating a cooling medium therein or any external cooling device, etc. Indeed, according to one or more embodiments, the inert liquid cooling carrier can perform the cooling function in a satisfactory, efficient and simple manner. Thus, the system can comprise a conventional pipe that can be conveniently and safely used for transporting the at least one liquid organic peroxide mixed with the inert liquid cooling carrier from the temperature controlled section to the polymer melt processing equipment.

[0071] According to one or more embodiments, the pipe can have a length of from 5 m to 200 m, such as from 10 m to 100 m.

[0072] According to one or more embodiments, the pipe comprises a single-walled pipe.

[0073] According to one or more embodiments, the pipe can comprise a plurality of segments having different lengths and / or arranged in different directions. For example, the plurality of segments can be connected to each other by straight or curved connectors, joints, elbows and similar connecting components.

[0074] According to one or more embodiments, the mixer comprises or is a static mixer, for example for continuous mixing of liquids.

[0075] According to one or more embodiments, the temperature-controlled segment further comprises an injector for injecting an inert liquid cooling carrier into the mixer at a predetermined temperature, for example 5 °C to 25 °C. For example, the injector can be configured to inject an inert liquid cooling carrier fluid within a temperature lower and upper limit to prevent freezing and warming up of the at least one liquid organic peroxide, respectively. To this end, the injector can be provided with a temperature regulator.

[0076] According to one or more embodiments, the injector can be configured to inject the inert liquid cooling carrier into the mixer at a predetermined flow rate, for example 1000 ppm to 5000 ppm, for example in an adjustable manner, based on the polymer production volume of the processing equipment.

[0077] According to one or more embodiments, the temperature-controlled segment further comprises a pump, for example based on the production volume of the polymer processing equipment, for pumping the at least one organic peroxide to the mixer at a predetermined flow rate, for example 10 ppm to 6000 ppm, 10 ppm to 5000 ppm. For example, the pump can be any liquid metering pump suitable for injecting a metered amount of liquid into another liquid.

[0078] The polymer melt processing equipment can comprise an extruder and can comprise any of the exemplary features described above with reference to the polymer melt processing equipment that can be used in embodiments of the above-described method. BRIEF DESCRIPTION OF DRAWINGS

[0079] Figure 1 A schematic diagram of a system for changing the rheology of a polymer according to one embodiment of the present disclosure is illustrated. DETAILED DESCRIPTION

[0080] For the purpose of illustration and not limitation, embodiments of a method and system for feeding at least one liquid organic peroxide to a polymer melt processing equipment and for melt processing a polymer are presented below.

[0081] A system for melt processing a polymer according to one embodiment of the present disclosure is schematically shown in Figure 1In, and generally indicated by reference numeral 12 in the accompanying drawings. Melt processing of the polymer may, for example, include polymer degradation and / or crosslinking, the polymer being, for example, polypropylene.

[0082] System 12 includes a system for feeding liquid organic peroxides into polymer melt processing equipment (described in more detail below) and melt processing equipment including venting zone 10.

[0083] exist Figure 1 In the illustrated embodiment, the melt processing equipment is an extruder 9 disposed outside the temperature-controlled section, which is generally indicated by reference numeral 3. However, the system may include any type of melt processing equipment disposed outside the temperature-controlled section 3.

[0084] The extruder 9 includes a feed hopper 8, a melt compression zone (not shown), and a depressurization zone including a venting zone 10, which is located downstream of the feed hopper 8. The venting zone 10 may have at least one vent (not shown). The extruder 9 may be a twin-screw extruder, such as, for example, a co-rotating, closely meshing twin-screw extruder.

[0085] For example, the temperature-controlled section 3 may have a housing that is maintained at a predetermined temperature (e.g., 10°C to 20°C) by means of HVAC.

[0086] exist Figure 1 In the illustrated embodiment, the temperature-controlled section 3 includes a reservoir 1 (e.g., a storage tank) for a liquid organic peroxide 13 and a mixer 5 for mixing the liquid organic peroxide 13 with an inert aqueous cooling carrier 4. The liquid organic peroxide 13 may be, for example, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, and the inert aqueous cooling carrier 4 may be, for example, softened water. For example, the softened water may contain less than 2%, less than 1%, less than 0.5%, less than 0.1%, or be free of dissolved compounds such as salts. The storage tank may be any storage tank known in the art for safely storing liquid organic peroxides and complying with safety regulations established for such materials. The mixer 5 may be a static mixer for continuously mixing liquids.

[0087] The temperature-controlled section 3 also comprises an injector (not shown in detail) for injecting the inert aqueous cooling carrier 4 into the mixer 5. The injector can inject the inert aqueous cooling carrier 4 at a predetermined flow rate, for example comprised between 1000 ppm and 5000 ppm, in relation to the production capacity of the polymer processing plant. For example, the flow rate of the inert aqueous cooling carrier 4 can be at least twice, for example three times higher than the flow rate of the liquid organic peroxide 1. The injector can inject the inert aqueous cooling carrier 4 at a predetermined temperature, for example comprised between 5 and 25 °C, of the liquid organic peroxide 13. To this end, the injector can be provided with a temperature regulator. The temperature of the inert aqueous cooling carrier 4 can be selected and / or adjusted within a lower temperature limit and an upper temperature limit, to prevent freezing and warming up of the liquid organic peroxide 13, respectively. For example, when the liquid organic peroxide 13 is 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, the temperature can be comprised in the range of 10 °C to 40 °C.

[0088] The temperature-controlled section 3 also comprises a pump 2 for pumping the liquid organic peroxide 13 to the mixer 5 at a predetermined flow rate, for example comprised between 50 ppm and 6000 ppm, in relation to the production capacity of the polymer processing plant. For example, the pump 2 can be any liquid metering pump suitable for injecting a metered amount of liquid into another liquid.

[0089] The system for feeding the liquid organic peroxide to the extruder 9 comprises the temperature-controlled section 3 and a pipe 6 configured to put the mixer 5 in fluid communication with the extruder 9 arranged outside the temperature-controlled section 3. The pipe 6 is not provided with any external temperature control component, such as for example a cooling jacket or a double wall for circulating a cooling medium therein, and the like. In fact, the cooling function of the liquid organic peroxide 13 is performed by the inert aqueous cooling carrier 4. Therefore, the pipe 6 can be a conventional single wall pipe, which does not need to be provided with any specific cooling component. The pipe 6 can have a length comprised between 5 m and 200 m, but different lengths are possible depending on the size of the system 12 for melt processing the polymer and on the layout of its equipment.

[0090] According to embodiments of the present disclosure, an exemplary method for melt processing a polymer, including degradation and / or crosslinking of, for example, polypropylene, can be as follows by using at least one organic peroxide such as, for example, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane. An exemplary method for melt processing the polymer includes delivering a liquid organic peroxide 13 in an undissolved mixture with an inert aqueous cooling carrier 4, such as, for example, demineralized water, from a temperature-controlled section 3 into a hopper of an extruder 9, extruding a molten polymer in the presence of the liquid organic peroxide 13 and the inert aqueous cooling carrier 4 in the extruder 9, and removing the inert aqueous cooling carrier 4 and any additional volatile compounds from the molten polymer. To form the mixture of the liquid organic peroxide 13 and the inert aqueous cooling carrier 4, the method can further include storing the liquid organic peroxide 13 in a reservoir 1 disposed in the temperature-controlled section 3, pumping the liquid organic peroxide 13 from the reservoir 1 to a mixer 5 at a predetermined flow rate, such as, for example, 500 ppm, in relation to the production volume of the polymer processing equipment, feeding the inert aqueous cooling carrier 4 to the mixer 5 at a predetermined flow rate, such as, for example, 2500 ppm, in relation to the production volume of the polymer processing equipment, and mixing the liquid organic peroxide 13 and the inert aqueous cooling carrier 4 in the mixer 5.

[0091] The liquid organic peroxide 13 with the undissolved mixed inert aqueous cooling carrier 4 is fed through a conduit 6 to the extruder feed hopper 8 together with polypropylene powder or pellets 7, for example under a nitrogen blanket. Along with the liquid organic peroxide 13, the inert aqueous cooling carrier 4, and the polymer powder or pellets 7, any stabilizers and / or other additives can also be fed through the feed hopper 8 to the extruder 9. The extruder 9 receives the composite material by means of one or more rotating screws, for example at an extrusion temperature in the range of 190 °C to 260 °C. The polymer, the liquid organic peroxide 13, and the inert aqueous cooling carrier 4 are mixed by the screws of the extruder 9.

[0092] The extrusion pressure and temperature can vary along the length of the extruder 9. For example, the melt pressure in the melt compression zone can be about 100 bar at a temperature of about 230 °C. During the reactive extrusion process, the liquid organic peroxide 13 causes rheological modification of the molten polymer.

[0093] Because the extruder 9 comprises a degassing zone 10 downstream of the extruder hopper 8, it is possible to extract the demineralized water, which previously served as an inert aqueous cooling carrier 4 for the liquid organic peroxide 13, along the pipe 6 as a vapor 11 from the polymer melt. In addition, other volatile compounds and reaction products from the peroxide degradation reaction can be removed with the water. The vacuum pressure required for the complete extraction of the inert cooling carrier consisting of demineralized water as well as other volatile compounds can be selected at a negative pressure in the degassing zone, for example between 1000 mbar(a) and 800 mbar(a), for example between 800 mbar(a) and 600 mbar(a). The negative pressure in the degassing zone can be maintained at the desired level, for example by attaching at least one degassing port to a pipe leading to a vacuum pump or other known device for generating a vacuum. The degassed polymer leaves the extruder 9 in the form of granules via a pelletizer (not shown).

[0094] As a result, an improved reduction of VOCs, an enhanced reduction of odor and an improved color of the final polymer granules can be achieved.

[0095] In the described embodiments, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane is described as a liquid organic peroxide for modifying the rheology of a polymer such as polypropylene under extrusion conditions. However, according to the method embodiments of the present disclosure, different polymers can be rheologically modified by different organic peroxides. In addition, embodiments based on the use of a single organic peroxide are also described. However, according to one or more embodiments of the method of the present disclosure, multiple organic peroxides can be used. In addition, according to one or more embodiments of the method of the present disclosure, stabilizers and / or other additives can also be used.

[0096] While the present disclosure has been described with reference to a limited number of embodiments, those skilled in the art having benefit of the present disclosure will appreciate that other embodiments can be devised which do not depart from the scope of the present application as disclosed herein. Accordingly, the scope of the present application should be limited only by the appended claims.

Claims

1. A method for feeding liquid organic peroxide to a polymer melt processing equipment, the method comprising: storing at least one liquid organic peroxide (13) in a reservoir (1) arranged in a temperature controlled section (3); mixing the at least one liquid organic peroxide (13) and an inert cooling carrier (4) in a mixing section arranged in the temperature controlled section (3), wherein the mixing is performed without dissolving the at least one liquid organic peroxide (13) in the inert cooling carrier (4); and and delivering the at least one liquid organic peroxide (13) with the inert cooling carrier (4) from the temperature controlled section (3) to a polymer melt processing equipment arranged outside the temperature controlled section in the form of an undissolved mixture, wherein the inert cooling carrier (4) comprises an aqueous liquid that volatilizes under melt processing conditions.

2. The method according to claim 1, wherein the inert cooling carrier (4) consists of demineralized water.

3. The method according to claim 1 or claim 2, wherein the polymer melt processing equipment comprises an extruder (9).

4. The method according to claim 1 or claim 2, wherein the mixing is mechanical mixing.

5. The method according to claim 1, wherein the method further comprises feeding the inert cooling carrier (4) to the mixing section at a predetermined flow rate.

6. The method according to claim 1, wherein the method further comprises pumping the at least one liquid organic peroxide (13) from the reservoir (1) to the mixing section at a predetermined flow rate.

7. The method according to any one of claims 1, 2, 5 or 6, wherein the polymer is a polyolefin.

8. A method for melt processing a molten polymer, comprising a method for feeding at least one liquid organic peroxide (13) to a polymer melt processing equipment as defined in any one of claims 1, 2, 5 or 6, wherein the method for melt processing the molten polymer further comprises melt processing the molten polymer in the polymer melt processing equipment in the presence of the at least one organic peroxide (13) and the inert cooling carrier (4), and removing the inert cooling carrier (4) from the molten polymer.

9. The method according to claim 8, wherein the melt processing comprises extrusion.

10. The method according to claim 8 or claim 9, wherein the removing is performed by venting the polymer melt processing equipment.

11. A system for feeding liquid organic peroxide to a polymer melt processing equipment, the system comprising: a temperature controlled section (3), the temperature controlled section (3) comprising: a reservoir (1) of at least one liquid organic peroxide (13); and a mixer (5) for mixing the at least one liquid organic peroxide (13) with an inert liquid cooling carrier (4) without dissolving the at least one liquid organic peroxide (13); and a polymer melt processing equipment arranged outside the temperature controlled section. a pipe (6) configured to put the mixer (5) in fluid communication with polymer processing equipment arranged outside the temperature controlled section (3), wherein the pipe (6) is not provided with cooling means.

12. The system according to claim 11, wherein the mixer is a static mixer.

13. The system according to claim 11 or claim 12, wherein the temperature controlled section (3) further comprises an injector for injecting the inert liquid cooling carrier (4) into the mixer (5) at a predetermined flow rate.

14. The system according to claim 11 or claim 12, wherein the temperature controlled section (3) further comprises a pump (2) for pumping the at least one liquid organic peroxide (13) to the mixer (5) at a predetermined flow rate.

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