A process for recycling expandable plastic materials and the expandable or plastic expanded materials obtained therefrom.

Abstract

A process for recycling and / or formulating expandable plastic materials using a system 1 is disclosed, which includes: an extruder 10, a heat exchanger-mixer 20, said process comprising the steps of: Melting in an extruder 10, cooling in a heat exchanger-mixer 20, and controlling the melt pressure by a melt pump 150 is followed by pelletizing, extrusion of an injection molding in which a first expansion agent (81) is not degassed during a melt processing in the system 1 as it is essentially incorporated into the pelletized expandable plastic material 130 or used to form the extruded, formed and expanded plastic material 140 or the expanded plastic article 150. The present invention also relates to a granulated expandable plastic material 130, a formed and expanded extruded plastic material 140, and a molded expanded plastic article 150 obtainable by the process.

Description

A process for recycling expandable plastic materials and an expandable or expanded plastic material obtainable thereby. History of invention The present invention relates to a process for recycling and / or formulating expandable plastic materials, the present invention also relates to a recycled and / or formulated expandable or expanded plastic material obtainable thereby. Expanded plastics have been known for a long time and have proven useful in many applications. Such foams may be produced by foaming polyethylene, polypropylene, polyester or polystyrene beads impregnated with blowing agents and then welding together the foam beads thus produced to form shapes. Expandable polystyrene is commonly known as EPS. Important applications of EPS and other expandable plastics include thermal insulation in structures and buildings, containers, cups or packaging, or reinforced panels with acoustic barriers in buildings and structures. However, an increasing concern in recent years has been the disposal or recycling of expandable or expandable plastic waste. The main problems associated with recycling post-consumer EPS waste are the high specific transport costs due to the very low bulk density and the very low value creation due to the poor purification effect and poor economic viability. For this reason, the main component of the waste is thermally recycled. For EPS methods such as pre-foamers and molders, it would be beneficial to have a process for reprocessing special material (e.g., too small or too large fertilized pellets) or for upgrading EPS produced by the suspension method to easily upgrade an EPS stock to include added value and / or functional additives. Currently known or proposed methods for recycling waste-fertilized thermoplastics only allow for partial recycling of waste expandable plastic materials and their components. For example, US 6,310,109 B1 discloses dissolving up to 30% of the recycled expanded PS material in monomeric styrene prior to suspension polymerization. However, it is expected that the dissolved polystyrene and its various additives may interfere with the subsequent suspension polymerization. In addition, the presence of comonomers, especially cross-linking comonomers, may interfere with the decomposition of the recycled EPS in monomeric styrene. Similarly, US 8,173,714 B1 discloses a process for preparing EPS pellets comprising thermally non-conductive particles and having a reduced thermal conductivity by suspension polymerization in which about 13% of the EPS oversize or undersize components (expandable microspheres or granules comprising essentially the blowing agent) are dissolved in styrene prior to suspension polymerization thereof. It is expected that the blowing agent is lost during the decomposition process and the dissolved polystyrene and its various additives may interfere with subsequent suspension polymerization. There is therefore a need for methods for recycling waste expandable plastic materials more completely and effectively than is possible by dissolving small amounts of waste expandable plastic material in its monomer prior to a suspension polymerization step. WO 03 / 053651 A1 generically discloses an extrusion process for producing expandable thermoplastic polymer pellets and claims that it may contain up to 30% recycled product or waste products from previous processes. However, no specific disclosure is provided as to how this may be done, particularly without loss of the expanding agent, or examples of such processes are actually provided. EP1925418A1 discloses a process for the continuous melt-fertilization of a thermoplastic to produce foamed or foamable pellets from a polymer melt of a recycled polymer melt. In which at least part of the recycled polymer melt is produced from polymer pellets containing recycled promoter. The polymer pellets containing recycled promoter are melted in a melter and the promoter contained in the polymer pellets containing recycled promoter is removed from the recycled polymer melt in a degassing device. At least one additive is added in metered form to the recycled polymer material downstream of the degassing device. The polymer melt is either produced directly in a polymerization plant comprising a reactor and a degassing device or by melting the polymer pellets in a polymer melt melter charged with a liquid promoter. Until a polymer melt containing promoter is obtained, the promoter being dispersed and homogenized in a subsequent mixing device.The polymer melt containing the promoter and the recycled polymer melt containing the additive are then mixed and homogenized in a subsequent mixing device to form a homogenized polymer material which is then subjected to a granulation step carried out by a granulator. Although useful, the method and plant of EP '418A1' allow for only a partial recovery of the promoter-containing granules as a conventional "virtual" melt also requires a feed stream, and the promoter of the polymer granules containing the promoter is lost in the degassing step. It is therefore desirable to have an improved process for recycling expandable plastic materials. For example, it is desirable to be able to process an entire stock consisting essentially of recycled expandable plastic material only. However, it is desirable to have a simple and straightforward melting process for preparing formulated and / or upgraded grades of expandable plastic material from a stock of expandable plastic pellets as is available from conventional suspension polymerization or melt impregnation processes. It is also desirable to have a pelletized expandable plastic material, an extruded, foamed expanded plastic material, or a molded expanded plastic article obtainable or obtained by such processes. Summary of the invention Starting from this state of the art, it is an object of the invention to provide an improved process for recycling and / or formulating expandable plastic materials which does not have the aforementioned drawbacks, in particular a lack of complete and effective recycling of the expandable plastic material and a significant loss of expansion factor. An additional object is to provide a process which does not necessarily require unrecycled or "virgin" melt streams. Other objects of the invention include providing a granulated expandable plastic material, an extruded and foamed expandable plastic material or a molded expanded plastic article obtainable or obtainable by the process of the invention. According to the invention, these objects are achieved by a process for recycling expandable plastic materials using a system comprising the following devices in fluid communication with each other and in the following sequence. -An ejector device -A heat exchanger-mixer The open system includes a melt pump device also in fluid communication with the previously mentioned devices, In which the melt pump device is either located upstream of the heat exchanger-mixer device and downstream of the ejector device, or the melt pump device is located downstream of the heat exchanger-mixer device. This process includes the following steps: - Melting a melt comprising an expandable plastic material comprising a first expanding agent in an extruder to form a molten expandable plastic material. -Cooling the expandable plastic material in the heat exchanger-mixer device -Controlling the pressure of the molten expandable plastic material using a melt pump device, And later or (i) Granulating the molten expandable plastic material by a granulating apparatus to form a granulated expandable plastic material. (ii) ejecting the molten expandable plastic material through a mold to a controlled reduced pressure, preferably atmospheric pressure, to provide an extruded, foamed, expanded plastic material, or (iii) injection molding the molten expandable plastic material by an injection molding machine to form a molded expanded plastic article, wherein the expandable plastic material comprises at least 40%, more preferably 60%, even more preferably 90% by weight, and still more preferably necessarily all of the melt flow. wherein the system does not have a degassing device and wherein the first expanding agent is not degassed during the processing of the melt in the degassing system such that the first expanding agent is substantially contained in the granulated expandable plastic material or is used to form either the extruded, foamed and expanded plastic material or the molded expanded plastic article. The inventors have surprisingly found that the process may be used for both complete recycling of recycled pure expandable plastic material and / or for the formulation or upgrading of pre-existing expandable plastic granule material. The recycling and / or formulation process is thus significantly improved over the prior art. In particular, the inventive process maintains very little loss of expanding agent, and thus in many instances little or no additional expanding agent dosage is required. Furthermore, not only the expanding agent may be recycled in the present invention, but any additives included in the expandable plastic material are recycled. Furthermore, since very little or no expanding agent needs to be added to and mixed with the expandable plastic material used as a filler, a lower overall processing temperature profile and melting temperature may be advantageously used.For example, temperature-sensitive additives such as flame retardants may be added directly, for example in the ejector without the need for special additional equipment such as a side ejector or a second cooler or special flame retardant stabilizer packages. In the case of formulating or upgrading an expandable plastic granulate such as that obtainable from conventional suspension polymerization or melt impregnation processes. The scale of the plant and production lines may be significantly reduced because the granulate already contains the expanding agent. In addition, the expandable plastic granulates may be conveniently and centrally produced in large scale and efficient production facilities and then the upgraded or corrected formulations or grades (even in relatively small quantities) may be produced as the customer requires. Such formulating and upgrading means may then be conveniently distributed geographically to regional locations to meet local market and product needs. In addition, since the recycling and / or formulating or upgrading process does not require a suspension polymerization step, the use of solvents is avoided. This lack of need for extensive heat processing and high processing temperatures is a result of using a melt of an expandable plastic material, preferably in the form of pellets, for the extruder where it is melted and further processed. In some embodiments, the non-expandable plastic material may be used as part of the melt for the extruder, for example, either as pellets or in the form of a molten stream. However, the plastic material flow to the extruder will preferably be at least 40%, more preferably 60%, even more preferably 90% by weight, and still more preferably essentially only the expandable plastic material. In a particularly preferred embodiment, only the expandable plastic material in the form of pellets is used as a melt stream for the extruder. In certain embodiments, the process involves either pelletizing or extrusion only. In other embodiments, pelletizing is performed followed by subsequent injection molding. In still other embodiments, a neutralizing system is provided at a location between the heat exchanger-mixer and the injection molding machine to facilitate the transition between the usually continuous or semi-continuous extrusion process and the injection molding or discontinuous process. A granulated expandable plastic material obtainable preferably obtained by the process of the invention wherein a granulating device is present. wherein the granulating device is an underwater or filament granulator and granulation of the clarified molten expandable plastic material is carried out to form a granulated expandable plastic material preferably comprising one or more basic additives, preferably at least one flame retardant compound and at least one from the group consisting of a melt stabilizer, a synergist, an infrared reflector, an infrared absorber, a pigment, a nucleating agent and a wax. A third further object of the invention is to obtain a formed and expanded extruded plastic material. By the process of the invention, in which the molten expandable plastic material or the molten expandable plastic material is flattened by a die to a controlled reduced pressure, preferably atmospheric pressure, to form a formed and expanded extruded plastic material, preferably comprising one or more basic additives, preferably at least one flame retardant compound and at least one of the group consisting of an infrared reflector, an infrared absorber, a pigment, a nucleating agent and an extruded wax. In many instances, it will be preferable that the expandable plastic material is obtained in the process stream from a suspension polymerization process such as the process conventionally most widely used for producing expandable plastic pellets. These other objects of the invention share the advantages achieved by the process of the invention. Including the complete recycling of recycled resins into pure expandable plastic material and / or the formulation or upgrading of pre-existing plastic granulate resins with only very little loss of expansion factor and thus allowing the advantageous use of a generally lower processing curve and melting temperature. In certain specific examples, the maximum melting temperature in the process is 210, preferably 200, again preferably 190 even more preferably 180 and again preferably 175 degrees Celsius. As a result of this intermediate processing in the present invention there is only a limited reduction in Mw and Mn and only a limited increase in Mw to Mn of the expandable plastic material during processing. In some examples, the decrease in Mn is less than 40%, preferably 30%, and the decrease in Mw is less than 20%, preferably 15%, and the increase in Mw to Mn is less than 35%, preferably 25%. In preferred embodiments, the melt-expandable recycled plastic material, the flattened melt-expandable plastic material, the granulated expandable plastic material, or the formed and expanded extruded plastic material of the invention has molecular weight properties of a Mw of 150 to 250 kDa (absolute) and a Mw / Mn of between 1.2 and 2.5 when measured by GPC using THF as the solvent. Such molecular weight properties provide desirable processing and / or mechanical properties for the resulting products. In a preferred embodiment of the process and system of the invention, a means of measuring the desired expansion agent is absent from the system and no additional desired expansion agent is added. This embodiment has the significant advantage of simplifying the system and process of the invention, thereby reducing investment and maintenance costs and eliminating the complexity and potential hazards of gaseous feedstocks. These advantages are attributable to the use of an expandable plastic material as the primary or even sole feedstock in the process of the invention. In one embodiment of the process of the invention, one or more optional static mixer(s) are present and additional mixing of the molten expandable plastic material is performed by the optional static mixer(s) and a melt strainer is present and a straining of the molten expandable plastic material is performed by the melt strainer to form a strained molten expandable material prior to subsequent extrusion granulation or injection molding. In yet other embodiments, additional static mixers may be present. A static mixer is particularly useful when adding additional components such as expansion agents as the static mixer promotes dispersion of the expansion agent or other component in the molten expandable material. A melt strainer is particularly useful for use with recycled seeded seed streams which may be contaminated with particulates and the use of a filter will reduce clogging and therefore mold cleaning and maintenance when using underwater granulation and potentially also filament granulation with thread and thread mold hole sizes. In another embodiment of the invention, a means for measuring the desired expansion agent is provided and the desired addition of additional expansion agent is accomplished by means of the desired expansion agent measuring means. This embodiment is advantageously used when the waste expandable plastic material to be recycled and fed to the extruder for melting is old and worn and the expansion agent is lost. In various embodiments, the amount of additional expansion agent added is less than 4, preferably 3, and even more preferably 2, most embodiments being 1% by weight based on the mass of the total polymer melt. Alternatively, this embodiment may be used when recycling the formulation or upgrading the expandable plastic material for another application that requires higher levels of expansion agent or when the addition of an auxiliary expansion agent to the expandable plastic material is desired. In a specific example of the above process example, the expansion agent metering device is placed to inject the desired expansion agent into the extruder unit, preferably a twin-screw extruder. Injecting into the extruder for dispersion and mixing without the use of a static mixer requires less investment and allows for a potentially smaller footprint due to the lack of a static mixer. A twin-screw extruder is preferred due to its additional dispersion and shear mixing compared to single-screw extruders. However, the use of an ejector device instead of a static mixer(s) for dispersing and mixing the desired expansion agent will often be less flexible in terms of the processing window and the screw design required for the process. Thus, in an alternative embodiment, the desired static mixer(s) are / are present and the desired additional mixing of the molten expandable plastic material is performed by the desired static mixer(s). And the expansion agent metering device is placed in order to inject the desired expansion agent and / or before the static mixer(s). In a particularly preferred embodiment, at least two static mixers are present, in which a dispersing step is performed in a first static mixer and which subjects the mixture to intensive mixing. And in which a holding step is performed in a second static mixer and which subjects the mixture to less intensive mixing (homogenization) than in the first static mixer.This sample advantageously provides sufficient time for the expansion agent to decompose and mix into the molten polymer. According to a specific example of the process in which the desired blowing agent is injected, it comprises one or more blowing agents, preferably an inert gas, such as methylol, methyl formate, pentane, butane, or mixtures thereof. These blowing agents are less harmful to the environment. In another embodiment, a masterbatch is added to the extruder, preferably a single-screw extruder. Single-screw extruders lack the dispersion and mixing properties of twin-screw extruders. Masterbatch is therefore suitably used to enhance the dispersion and mixing of additives by single-screw extruders. Masterbatch allows the processor to economically formulate and upgrade the expandable plastic material during the process of the invention. The additive masterbatch may modify various properties of the base expandable plastic material such as its ultraviolet resistance, flame retardancy, antistatic fluidity, anti-slip, corrosion inhibition, antimicrobial, antioxidant, ejection or phosphorescent properties. Preferred additives in the present invention include infrared absorbers or reflectors (e.g. graphite), nucleating agents and flame retardants. In another embodiment having similar advantages to the previous embodiment, an additive is added to the extruder, preferably a twin-screw extruder. Due to the favorable shear dispersing and mixing properties, a twin-screw extruder can flexibly add additives without the need for the use of main parts. A person skilled in the art will understand that combinations of the subject matter of the claims and the preceding examples of the invention are possible without limitation in the invention to the extent that such combinations are technically feasible. In such combinations, the subject matter of any claim may be combined with the subject matter of one or more other claims. In such combinations, the subject matter of any process claim may be combined with the subject matter of one or more other process claims or the subject matter of one or more granulated expandable recycled plastic material or formed or expanded extruded plastic material or molded expanded plastic article claims or the subject matter of a mixture of one or more process claims and material or article claims. By analogy, the subject matter of any material or article claim may be combined with the subject matter of one or more material or article claims of one or more process claims or the subject matter of a mixture of one or more material or material claims and process claims. By way of example, the subject matter of any claim may be combined with the subject matter of any number of other claims without limitation to the extent that such combinations are technically feasible. The skilled person will understand that it is possible to combine the subject matter of different examples of the invention without limitation to the invention. For example, the subject matter of one of the process examples mentioned above may be combined with the subject matter of one or more of the material examples mentioned above or vice versa without limitation to the extent technically feasible. Brief description of the shapes Hereinafter, the invention will be described in more detail with reference to various embodiments of the invention as well as the figures. The summary figures show the following: Figure 1 is a schematic view of five examples of a process and a system for recycling and / or formulating expandable plastic materials by making a granulated expanded recycled plastic material, a formed and expanded extruded plastic material, or a molded expanded plastic article. The system includes an extruder, a heat exchanger-mixer, a melt pump, along with a mold, pelletizer, and / or injection molding machine. Figure 2 shows a schematic view of three examples of a process and system for recycling and / or formulating expandable plastic materials by making a granular expandable recycled plastic material. The system includes an ejector, a heat exchanger-mixer, a melt pump, and a pelletizer. Figure 3 shows a schematic view of three examples of a process and system for recycling and / or formulating expandable plastic materials by making an extruded, formed, expanded plastic material. The system includes an extruder, a heat exchanger-mixer, a melt pump, and a mold. Figure 4 Expanded pearls having densities of (a) 21 g / L (Mag = 20X) and (b) 11 g / L (Mag = 12X) produced from a granulated expandable plastic material produced by an exemplary process of the invention. Table 1 compares the molecular weight properties of expandable plastic (EPS) materials before and after the inventive process. Detailed description of the invention Definitions As used in the specifications and claims of this application, the following definitions shall apply: "A", "an" and "the" as a noun may refer to either the singular or the plural unless the context indicates otherwise. An "expandable plastic material" is a plastic material that contains a substantial amount of blowing agent, an amount detectable by high-pressure gas chromatography. In some embodiments, the amount of blowing agent in the expandable plastic material is at least 1% by weight, preferably 4 to 8% by weight. An expandable plastic material is thus distinguished from an expanded or previously foamed product (containing at most only low levels of residual blowing agent) obtained by molding or extruding an expandable plastic material such as EPS. One skilled in the art will appreciate that expandable plastic beads obtained from conventional suspension polymerization and melt fertilization processes are readily distinguishable from each other by their appearance and chemical composition. The granules from the suspension polymerization process have a very nearly perfect spherical shape. Whereas the granules from the melt-casting processes have a less perfect spherical shape because they are produced using underwater or filament granulators. In addition, the granules may be distinguished from each other because the granules from the underwater or filament granulator (melt-casting processes) show cut lines on their surface from contact with the cutting blade or knife, whereas such cut lines are absent from the surface of the granules prepared by the suspension polymerization method. In addition, surface active systems are known specifically for use in stabilizing expandable plastic pellets produced by suspension polymerization. Such surface active materials may also be referred to by other terms such as suspension stabilizers, suspending agents, stabilizers or protective colloids. These surface active materials are usually used in conjunction with a Pickerings stabilizer (or protective colloid) as described in US8173714B2. Alternatively, they may be used in conjunction with a negative ion surface active material or alone. It is important to note that such surface active systems are not used in the melt impregnation process for preparing expandable plastic pellets. Some representative surface-active systems and their components are organic suspending agents, stabilizers and negative ion surface-active materials, disclosed in US 7,825,165B2, stabilizers or suspending agents, disclosed in WO2014 / 009145A1, protective colloid, disclosed in DE3331570A11 and stabilizers and protective colloids disclosed in US4036794A1. Expandable plastic granules prepared by suspension polymerization methods and therefore containing surface active agents and / or their residues are chemically distinguished from those prepared by melt impregnation methods which do not contain those surface active agents or their residues. These surface active agents and their residues may be detected by conventional analytical methods such as those disclosed in "Additives in Polymers: Analysis and Industrial Applications" by Jan CJ Bart published by John Wiley and Sons in 2005 (ISBN: 978-0-470-85062-6). A "blowing agent" is a substance capable of producing a cellular structure through a foaming process in a plastic material that undergoes hardening, solidification or phase transition. It is conventionally known as a chemical or physical blowing agent. In the present invention, the blowing agent will preferably be a physical blowing agent. "The first expanding agent is substantially contained in the granulated expandable plastic material or used to form or form the formed and expanded extruded plastic material or the molded expanded plastic article." This means that little expanding agent is lost in the process of the invention. In one example, the loss of expanding agent will be less than 1, preferably 0.8, more preferably 0.6, and still more preferably less than 0.5 percent by weight measured based on the weight of the expandable plastic material, e.g., granules, and relative to the content of the first expanding agent introduced into the process by the expandable plastic material in the melt stream. For example, in some embodiments, the expandable plastic material in the melt stream will have a blowing agent content of about 4 to about 8, preferably about 5 to about 6, percent by weight, and the produced granulated expandable plastic material will have a blowing agent content of about 0.05 to about 0.8 percent by weight less when the melt stream consists essentially of the expandable plastic material and no additional blowing agent is added during the process. The amount of loss of the first blowing agent may be readily determined by comparing the amount of the first blowing agent with the total amount of blowing agent present in the granulated expandable plastic material produced by the process, taking into account, for example, any additional blowing agent added to the process and the amount of any non-expandable plastic material in the melt stream and the amounts of additives added, etc. For samples in which the product is directly extruded or injection molded. The amount of blowing agent may be measured by taking samples of the molten expandable plastic material shortly before the mold or injection molding machine, for example by means of a sprue. As an example of gas analysis, a gas chromatography cell may be used to measure the composition of the blowing agent in various product or intermediate samples as well as its content in modified analytical methods. Special multi-headroom extraction capillary gas chromatography (MHE-CGC) methods have been developed for the size, accuracy and rapid determination of volatile components in solids such as plastics. In particular, ASTM D4526 provides a standard procedure for the determination of volatiles in polymers by static headroom gas chromatography. Alternatively, thermal gravimetric analysis coupled with FTIR or MS may also be used for the analysis of volatiles in plastics. Several conventional methods for the analysis of volatile species such as blowing agents in additives in polymers: Analysis and Industrial Applications are disclosed in JCJ Bart, published by John Wiley and Sons, West Sussex, UK in 2005 (ISBN 0-470-85062-0). Alternatively, the blowing agent content may be measured indirectly by measurements of the density of the granular expandable plastic material, the formed and expanded extruded plastic material or the molded expanded plastic articles produced by the process of the invention. Such densities will be measured in accordance with ISO 845 or ASTM D1622. The densities of these products may then be compared with the densities of products obtained by processes in which only the virgin non-expandable plastic material has been used as a melt stream and to which known amounts of blowing agent have been added. In addition, the blowing agent content may also be measured directly by measuring the melt concentration in the extruder or other points in the system and comparing these values ​​with the melt concentrations of comparable non-expandable plastic materials under comparable process conditions of temperature, pressure and time and to which known amounts of blowing agent have been added. It is recalled that online near infrared (NIR) methods are known for controlling the blowing agent content of polymer beads. For example EP 1752236 B1 discloses such methods for controlling the blowing agent content of polymer beads used to make samples in a lost foam molding process. Thus in one example online NIR measurements may be used to measure and control the blowing agent content, for example, in the melt stream 101 and / or the molten expandable plastic material 110 so that an additional blowing agent addition 80 may be made to ensure a specified level in the granulated expandable plastic material 130 or to form a formed and expanded extruded plastic material 140 or a molded expanded plastic article 150. In other contexts the blowing agent content may be indirectly controlled by online rheometric measurements of the size. In the present invention, the control of the first expansion agent contained in an expandable plastic material (e.g. before, during or after completion of the inventive process) is defined as the content as determined by headspace gas chromatography. A "master piece" is defined in this application as a solid (granular or dry mixture) or liquid additive to an expandable plastic material used to impart specific properties to the expandable plastic material (additive master piece). Therefore, a masterbatch is usually a concentrated mixture of additives encapsulated during a thermal process into a carrier resin, which is then cooled and granulated. Masterbatch has found application in the formulation and upgrading of plastic materials. The numerical values ​​in this application relate to average values, unless otherwise indicated. The numerical values ​​are to be understood to include numerical values ​​which are the same when reduced to the same number of significant figures and numerical values ​​which differ from the stated value by less than the experimental error of a conventional measuring technique of the type described in this application for determining the value. A process or system for recycling expandable materials means that the product of the process or system comprises at least a portion of recycled expandable materials. The recycled expandable material comprises a primary expanding agent and is usually a special material (for example, very small or very large impregnated pellets). In each case, the recycled expandable material comprises the primary expanding agent and is usually in the form of granules or pellets. The first blowing agent is not particularly limited and will typically be a conventional physical blowing agent such as a CFC (e.g., CFC-11), an HCFC (e.g., HCFC-22, HCFC-142b, HCFC-134a, or HFC-365mfc), an HCC, an HFC, hydrocarbons (e.g., isobutene, a butane, a pentane, isopentane, or cyclopentane), methyl formate, methylol, water, nitrogen, CO2, or combinations thereof. The expandable plastic material in the liquid stream will typically comprise 1 to 10, preferably 2 to 9, preferably 5 to 8, percent by weight of the physical blowing agent. Thus, a recycled expandable material is part of a feed stream for the process or system. In various embodiments, the intermediates, the product processed or produced by the system (i.e., molten expandable material, flattened molten expandable material, granulated expandable material, or extruded, formed or expanded plastic material) which, depending on the particular process steps and devices of the drug system, comprises at least 25, preferably 50, preferably 75, even more preferably 90, percent by weight, still more preferably substantially all of the product as a recycled expandable material. Substantially all means that 100 percent by weight of the resin component of the product is recycled material, thus excluding the contribution of additives and / or expanding agents, etc. A process or system for formulating expandable plastic materials means that the product of the process or system comprises at least a portion of a pre-existing expandable material such as that produced by the conventional suspension method for EPS. Thus, one example refers to the upgrading of a pre-existing stock expandable material to include added value and / or functional additives. A pre-existing expandable material is therefore a feedstock for the process and system. In each case, the pre-existing expandable material comprises an expanding agent and will typically be in the form of granules or pellets. In various embodiments, the intermediates or product of the process or produced by the system (i.e., molten expandable material, flattened molten expandable material, granulated expandable material, or formed and expanded extruded plastic material, depending on the particular process steps and system apparatus) will comprise at least 50, preferably 60, preferably 75, or even more preferably 90 percent by weight, preferably substantially all of the product will be pre-existing as an expandable material.Essentially all means that all percentages by weight of the resin component of the product are from a pre-existing expandable material, thus ignoring the contribution of additives and / or expansion agents, etc. As previously discussed, the inventive process feature of fully recycling recycled melts into purely expandable plastic materials and / or formulating or upgrading pre-existing expandable plastic granulate melts with only very little loss of expansion agent thus allows for the beneficial use of a lower overall processing temperature profile and melting temperature. This is because the presence of the first expansion agent 81 acts to produce a viscosity of the molten plastic material in the extruder 10 and more reasonable temperature profiles there and lower maximum melting temperatures are possible. In certain embodiments, the viscosity of the respective melt in the extruder 10 may be conveniently measured by an online rheometer directly connected to the extruder 10 through an orifice such as a standard 18M orifice. One skilled in the art will appreciate that combinations of both recycling and formulating expandable plastic materials are possible in which both recycled expandable material and pre-existing expandable material flux streams are used. A feature of the process and systems of the various examples discussed above is that a substantial portion or even substantially all of the flux comprises a first expanding agent 81. Many of these examples will therefore require little or no addition of additional expanding agent 80. However, in some embodiments, additional blowing agent 80 will be added, for example, to increase the blowing agent loading in the melt expandable plastic material 110, for example, in upgrading or formulating a solution for an application that requires a higher blowing agent loading, or because some blowing agent has been lost from the melt expandable plastic material 100 due to storage for longer periods and / or at higher temperatures prior to the initiation of the inventive process. In some such embodiments, the melt viscosity is monitored online and additional blowing agent 80 will be added in an amount sufficient to maintain a desired constant melt viscosity. Additional blowing agent 80 is not particularly limited and will preferably be a physical blowing agent, in various embodiments the same as or different from the first blowing agent 81. In some embodiments, it will preferably not be a CFC, HCFC, HCC or HFC due to environmental considerations. Figure 1 shows a schematic view of three exemplary processes and systems 1 for recycling and / or formulating expandable plastic materials by making a molten expandable material 110 which is then later extruded or injection molded. These particular examples of system 1 have only one extruder 10, a heat exchanger-mixer 20, and a melt pump 50, and with a pelletizer 40, a mold 90, and an injection molding machine 95, these examples all lack the optional addition of the optional expansion agent 80 by means of the optional expansion agent metering device 70. In addition, the example in Figure 1(b) includes the addition of an additive 210 to an extruder and screw 12, and the example in Figure 1(c) includes a single-screw extruder 14. In the example in Figure 1(d), the molten expandable plastic material 110 is fed to an injection molding machine 95 by a neutralizing system 96. In the example in Figure 1(e), the molten expandable plastic material 110 is first directed to a granulated molten expandable plastic material 130 which is then fed to an offline injection molding machine 95. The process and system of the invention are not particularly limited unless otherwise stated. Processes and systems for preparing expandable polymers as well as their applications are known and are described, for example, in the Handbook of Polymer Foams edited by D. Eaves and published by Rapra Press of Shawbury, UK on 1. January 2004 (ISBN 1-85957-388-6) and the Handbook of Polymer Foams and Foam Technology 2nd Edition by D. Klempner, V. Sendijarevic and RM Aseeva published by Hanser Gardner Publ. of Munich, DE in April 2004 (ISBN 1-56990-336). Other disclosures of processes for preparing expandable polymer beads are found in US 4,243,717, US 5,000,891 and US 4,606,873. Unless specifically indicated otherwise. The process of the invention may include steps and use of polymers and raw materials such as are conventional and known in the art. Processing steps may include drying, grinding, mixing, feeding, conveying, homogenizing and formulating. Polymers used as raw materials for producing the melt expandable material 110 include polystyrene, polyolefins such as polyethylene or polypropylene, polyurethane, ethylene vinyl alcohol, polyvinyl alcohol, polycaprolactone, polylactic acid, starch, polyethylene terephthalate, polybutylene terephthalate, polybutylene terephthalate elastomer, polycyclohexane terephthalate, polyethylene naphthalate, engineering thermoplastics such as polycarbonate or polyphenylene oxide or blends and / or copolymers thereof. Additives for use in the process and system of the invention include additives to reduce friction (slip agents), light stabilizing antioxidants, anti-caking, anti-static, anti-fogging / wetting agents, dispersing technology, process stabilizers, infrared absorbers, infrared reflectors, and nanoparticulate ultraviolet absorbers. Thus, the melt expandable plastic material 110, the flattened melt expandable plastic material 120, the granulated expandable plastic material 130, and the extruded, formed, and expanded plastic material 140 may also include conventional additives in effective amounts such as colors, fillers, stabilizers, flame retardants, synergists, nucleating agents, lubricants, antistatic agents, pigments, carbon black, graphite, aluminum, inorganic particles, ultraviolet and heat non-conductive particles, and waxes. Such additives can be added via side streams, so it is possible to process liquid and solid additives as well as the main pieces.The homogenization necessary for uniform additive distribution in the product may be optimally achieved by the use of static mixers. Thus, in embodiments of the process of the invention, the melt expandable plastic material 110 or a flattened melt expandable plastic material 120, obtainable, preferably obtained in the process route, preferably includes one or more basic additives, preferably at least one flame retardant compound and at least one from the group consisting of a melt stabilizer, a synergist, an infrared reflector, an infrared absorber, a pigment, a nucleating agent and a wax. These melt expandable plastic materials are formulated and then subsequently granulated, extruded or indirectly or directly injection molded. The skilled person will understand that a granulated expandable plastic material 130, obtainable, preferably obtained by the process of the invention, preferably comprises one or more basic additives, preferably at least one flame retardant compound and at least one from the group consisting of a melt stabilizer, a synergist, an infrared reflector, an infrared absorber, a pigment, a nucleating agent and a wax. Wherein the expandable plastic material 100 in the melt stream 101 obtained from a suspension polymerization process is readily distinguishable from granulated expandable plastic materials known in the art.This is because the granulated expandable plastic materials in this sample have characteristics of both underwater granulation such as a less than perfect spherical shape along with the presence of cut lines on their surface, which will be a chemical signature of the suspension polymerization process such as a recognizable component of a surface active system or its residue. Therefore, the visual observation of cut lines on the surface along with the detection of a component of a surface active system or its residue by chemical analytical methods may be used to identify the unique granulated expandable plastic material 130 of this sample. The inventive system may include such devices, sub-devices and auxiliary devices as are conventional and known in the extrusion art including various types of pumps, hoppers, feeders, heat exchangers, static mixers, agitators, inducers, control systems, power supplies, liquid cooling and heating supplies and distributors, pumps, valves, pipes, lines, sources, barrels, tanks and sensors for measuring such parameters as flow rates, temperatures and pressures. The inventive process and system may be suitably controlled by a computer interface equipped with suitable sensors. Extrusion systems and their components and operating procedures are well known. For example, see Extrusion: A Guide and Handbook of Specific Processing by HF Giles Jr, EM Mount III, JR Wagner, Jr published by William Andrews of Norwich, NY in 2005 (ISBN 0-8155-1473-5. The extruder 10 is not particularly limited and may be a melt kneader, a single screw extruder 14 as shown in Figure 1(c) or a twin screw extruder 12 as shown in Figure 1(b). As shown in Figure 1(b), the process may include a step in which an additive 210 is added to the extruder 10, preferably a twin screw extruder 12. The heat exchanger-mixer device 20 is not particularly limited and may be a shell and tube heat exchanger, a direct contact heat exchanger, a spiral heat exchanger. Preferably, it may be a tubular heat exchanger with mixing and flow-closing components such as a Sulzer SMR static cooler-mixer. The melt pump device 50 is not particularly limited and may, for example, be a twin-shaft or single-shaft driven gear pump. It operates to ensure the necessary pressure build-up to allow for desired melt smoothness and pelletization at a very low energy input. One skilled in the art will appreciate that the location of the melt pump device 50 will typically be defined by the extruder used (i.e., single-screw or twin-screw) as well as the size of the system. Thus, a preferred embodiment of FIG. 1b would include a twin-screw extruder 12 with an additive port 210, a mixing heat exchanger 20, the melt pump device 50, and a pelletizing device 40 or die 90. A preferred embodiment of FIG. 1c would include a melt pump device 50 downstream of the single-screw extruder 14. Similarly, other preferred embodiments of systems based on single screw extruders 14 (e.g., FIGS. 2c and 3c) will have a second melt pump device 50 after the single screw extruder 50.In the process and system of the invention, typical temperatures in the ejector 10 will be at least about 110, preferably 120, preferably 140, more preferably 150 degrees Celsius, of the minimum melting temperature. Melting temperatures in the heat exchanger-mixer will typically be from about 150 to about 200, preferably from about 155 to about 190, preferably from about 160 to about 180 degrees Celsius. In many embodiments, the melting temperature in the heat exchanger-mixer 20 will be about the same as or preferably less than the temperature in the ejector. The difference between the maximum melting temperature in the ejector 10 and the maximum melting temperature in the heat exchanger-mixer 20 will be from zero to about 15 degrees. It is noted that melting temperatures may be conveniently measured by conventional flash-base melting thermocouples, for example, often mounted in the ejector cylinder but sometimes mounted in the mold adapter. In addition, the embodiments of FIG. 1 may optionally have additional devices, means, and steps (not shown) in preparing a molten expandable material. Such optional system features and process steps may include: one or more optional static mixer device(s) 60 for optionally further mixing the molten expandable plastic material 110; optional expansion agent metering means 70 positioned for injecting a desired expansion agent 80 into the ejector device 10; and / or at or before one of the optional static mixer devices 60; and an optional melt strainer (30) for optionally straining the molten expandable plastic material 110 to form a molten expandable material 120. It is noted that the examples of FIG. 1 extend downstream to a pelletizing device 40 such as an underwater pelletizer to make expandable pellets or a filament pelletizer to make foamed filaments or a mold 90 to make foamed tubes, sheets or other shapes, or they may continue indirectly or directly to an injection molding system 95 to make foamed articles in an integrated continuous or semi-continuous process. Figure 2 shows three exemplary processes and systems for preparing a granulated expandable plastic material 130. Thus, these examples all have a granulating device 40 for producing a granulated expandable plastic material 130 from a smoothed molten expandable plastic material 120. In addition, they show that an optional melt screening device 30 may be provided for performing a desired screening of the molten expandable plastic material 110 to form a smoothed molten expandable material 120. In exemplary examples (a) to (c) there is an addition of an optional additional expanding agent 80 by means of an optional expanding agent metering device 70. In example (a) the addition of the additional expanding agent 80 is to the extruder 10. In example (b) the addition is to a twin-screw extruder 12. In the example (c) of Figure 2, the expansion agent metering device 70 is arranged to inject the desired additional expansion agent 80 both in and before a static mixer 60, in particular a first static mixer 61, in which a dispersing step is carried out in a first static mixer 61 and in which the mixture is subjected to intensive mixing and in which a holding step is carried out in a second static mixer 62 and in which the mixture is subjected to less intensive mixing (homogenization) than in the first static mixer 61. Figure 2(b) shows that the desired static mixer(s) 60 may alternatively be used to simply provide additional mixing of the molten expandable plastic material 110 and the desired additional expansion agent 80 may be added beforehand as in this example or even not added at all (not shown). The examples in Figure 2 also show that the melt pump device 50 may be located upstream of the heat exchanger-mixer device 20 and downstream of the ejector device 10 as in Figure 2(a) or the melt pump device 50 may be located downstream of the heat exchanger-mixer device 20 and upstream of the pelletizer 40 (or alternatively a mold 90 or injection molding device 95) as in Figures 2(b) and (c). Figure 3 shows three exemplary processes and pressure systems for preparing a formed and expanded extruded plastic material 140. These examples therefore all have a mold 90 for producing a formed and expanded extruded plastic material 140 from a flattened molten expandable plastic material 120 or a molten expandable plastic material 110. The mold 90 is not particularly limited and may be a hanging cover type sheet mold for sheet products, a T-mold or circular mold for film products, a circular mold for pipe and tubing, an open or closed profile extrusion mold, or an auxiliary extrusion mold. The molds and their designs are disclosed, for example, in “Design of Extrusion Molds” by MM Kostic and LG Reifschneider in the Encyclopedia of Chemical Processing published in 2006 by Taylor & Francis (DOI: 10.1081 / E-ECHP-120039324). Like the example of Figure 2, the examples of Figures 3(a) and (b) show the addition of an additional expansion agent 80 by means of an expansion agent metering device 70 to a twin screw extruder 12 or a first static mixer 61, respectively. The examples of Figures 3(b) and (c) show that the inventive process and system may have more than one melt pump device 5 and the example in Figure 3(c) shows that a main piece 200 may be added to the extruder device 10, preferably a single screw extruder 14. Examples The following examples are set forth to provide a detailed description of how to process molten expandable plastic material 110, granulated expandable plastic material 130, formed and expanded extruded plastic material 140, and molded expanded plastic article 150 for those skilled in the art and the uses claimed herein are evaluated and are not intended to limit the scope of what the inventors contemplate as their invention. In all samples, headspace gas chromatography was used to measure the blowing agent content in the various feed streams as well as the produced granulated expandable plastic material. In some samples, the molecular weight properties of the produced granulated expandable plastic material were determined by GPC measurements. The absolute molecular weight of PS after processing in tetrahydrofuran (THF) was measured by gel permeation chromatography (GPC) using a Malvern GPCmax (Malvern Instruments Ltd., UK) with two I-MBHMW 3078 polar columns and one I-Guard 0748 polar organic guard column and a triple detector (reciprocating light scattering index and concentration meter). The dissolved samples were filtered before injection (ChromafilXtra PTFE syringe filter, 0.45 μm pore size). THF, HPLC grade 99.9% with stabilizer was purchased from Sigma Aldrich. It was used as received. The Viscotek TDAmax was first measured with a narrowly distributed polystyrene (PS) standard and validated with a wide-distributed PS control. The measurement error of Mn and Mw, PS was below 5%. Sample 1 A system 1 comprising a twin screw extruder 12 equipped with gravimetric dosing equipment and a pentane injection port, a first static mixer 61 and a second static mixer 62, an SMR type heat exchanger as a heat exchanger-mixer 20, two melt pumps 50, a diverter valve, a police filter as a melt filter 30 and an underwater granulator system as a granulator 40 was used in this example. The melt stream 101 consisted essentially of EPS containing approximately 4.5% pentane and nucleating agents as an expandable plastic material 100. A pentane loss of approximately 0.4% by weight was observed in a 130-grain expandable plastic material that had a pentane content of approximately 5% by weight when no additional expanding agent was added. It was confirmed in the test section that the pentane content could be increased when an additional pentane was injected into the twin-screw extruder 12. Sample 2 Another system 1 also included a twin screw extruder 12 equipped with gravimetric measuring equipment and a pentane injection port, a first static mixer 61 and a second mixer 62, an SMR type heat exchanger as a heat exchanger-mixer 20, two melt pumps 50, a diverter valve, a police filter as a melt filter 30 and an underwater granulator system as a granulator 40 were used in this example. The melt stream 101 consisted essentially of EPS containing approximately 60% by weight of pentane and nucleating agents as an expandable plastic material 100. This recycled material was formulated by adding 3.5% by weight of an infrared absorber. The overall melt temperature was controlled to be between 170°C and 172°C. A pentane loss of approximately 0.8 to 0.6 percent by weight was observed with this processing and thus the granulated expandable plastic material 130 had a pentane content of about 2.5 to about 4.5 percent by weight.A homogeneous dispersion of the infrared absorber was confirmed by optical microscopy, and microspheres with an average bead size of about 1.4 mm were produced. Sample 3 A system 1 comprising a twin screw extruder 12 equipped with gravimetric dosing equipment, an SMR type cooler as a heat exchanger-mixer 20, a melt pump 50, a diverter valve, a melt filter 30, and an underwater pelletizing system as a pelletizing device 40 was used in this example. The melt stream 101 consisted essentially of EPS containing approximately 5% by weight of pentane, nucleating agents, and an antistatic coating as an expandable plastic material 100. This recycled material was formulated by adding 3% by weight of an infrared absorber. The melt temperature in the extruder was optimized to be between 165 and 171°C and in the diverter valve to be between 152 and 154°C. Thus, a final melt temperature of 152 to 154°C could be achieved. A homogeneous dispersion of the infrared absorber was confirmed by optical microscopy. Sample 4 Another system 1 comprising a twin screw extruder 12 equipped with gravimetric dosing equipment, an SMR type cooler as a heat exchanger-mixer 20, a melt pump 50, a diverter valve, a melt filter 30 and an underwater granulator system as a granulator 40 were used in this example. The melt stream 101 consisted essentially of EPS containing approximately 5 to 8 weight percent of blowing agent and 2 to 4 weight percent of flame retardant as an expandable plastic material 100. This recycled material was formulated by adding 0.2 weight percent of nucleating agent and 4 weight percent of infrared absorber. The process was stabilized during a test run lasting approximately 12 hours, and the overall melt temperature was controlled to be between about 150°C and about 155°C. An expansion factor drop of approximately 0.2 to 0.5 percent by weight was observed in the granulated expandable plastic material 130. A homogeneous dispersion of the infrared absorber was confirmed by optical microscopy and microspheres were produced with an average bead size between about 1.35 and about 1.6 mm. These microspheres were then expanded using conventional commercial pre-foaming equipment to densities of 21 g / l and 11 g / l (Figure 4). This example therefore demonstrates that recycled EPS may be successfully reprocessed as a melt stream 110 using the process of the invention to give a granulated expandable plastic material 130. Which may be successfully expanded and molded using commercial equipment and processing conditions to give expanded and molded products substantially identical to those obtained from "virgin" EPS. Table 1 provides a summary table comparing the molecular weight properties of some expandable plastic (EPS) materials before and after the inventive processing. It can be seen that the degradation of the expandable plastic material is minimal upon processing for EPS recycling and that the range of molecular weight reduction and polydispersity index of the polymer expander used varies depending on the processing conditions. Processing conditions such as temperature and shear can be controlled to limit material degradation, particularly in the presence of flame retardants. While allowing for excellent dispersion of additives, such as nucleating agents or infrared absorbers / reflectors. The disclosed system 1 may be advantageously used to avoid degradation of the flame retardant present in the recycled expandable plastic material and / or the flame retardant that acts as a given additive. While various examples have been provided for illustrative purposes, the foregoing descriptions should not be construed as limiting the scope herein. Accordingly, various modifications, adaptations, and substitutions may be made by one skilled in the art without departing from the spirit and scope herein. Reference numbers 1System 10 ejectors 12 Double-screw extruder 14 Single-screw extractor 20Heat exchanger-mixer device 25 Degassing device 30 Optional molten material filtration device 40 grain processing machines 50 Melt Pumps 60 Custom static mixers 61First static mixer 62Second static mixer 70 Expansion factor measuring device 80 Additional expansion factor 81 First expansion factor 90 templates 95 Injection molding machine 96 Neutralizing system 100 expandable plastic materials 101 Flow of Matter 110 Molten expandable plastic material 120 Melt-blown plastic material, smoothed 130 Granulated expandable plastic material 140 Plastic material has fallen out, formed and expanded 150molded expanded plastic products 200 original pieces 210Additional

Claims

Patent claims 1. A process to recycle and / or formulate expandable plastic materials using a system (1) comprising the following units in fluid communication with each other and in the following sequence: - an extruder unit (10), wherein the extruder unit (10) is a twin-screw extruder, - a mixer-heat exchanger unit (20) the system (1) further comprising a melt pump unit (50) also in fluid communication with previous said units (10, 20), wherein the melt pump unit (50) is located either upstream of the mixer-heat exchanger unit (20) and downstream of the extruder unit (10) OR the melt pump unit (50) is located downstream of the mixer-heat exchanger unit (20), said process comprising the steps of: - melting a feedstream (101) comprising an expandable plastic material (100) containing a first expansion agent (81), wherein the amount of expansion agent in the expandable plastic material is at least 1 wt%, in the extruder unit (10) to form a molten expandable plastic material (110), - cooling the molten expandable plastic material (110) in the mixer-heat exchanger unit (20); - controlling the melt pressure of the molten expandable plastic material (110) by means of the melt pump unit (50), and subsequently either: (i) granulation of the molten expandable plastic material (110) by means of a granulation unit (40) to form a granulated expandable plastic material (130), (ii) extrusion of the molten expandable plastic material (110) by a die (90) to a controlled reduced pressure to yield an extruded, formed and expanded plastic material (140), OR (iii) injection molding of the molten expandable plastic material (110) by means of an injection molding unit (95) to form a molded expanded plastic article (150), characterized in that the expandable plastic material (100) comprises at least 40%, more preferably 60%, even more preferably 90 % by weight, and most preferably essentially all of the feedstream (101), wherein the system (1) does not have a degasification unit (25) and the first expansion agent (81) is not degassed during a melt processing in the system (1) such that the first expansion agent (81) is substantially contained in the granulated expandable plastic material (130) or used to form either the extruded, formed and expanded plastic material (140) or the molded expanded plastic article (150), wherein the first expansion agent (81) is a physical expansion agent, wherein the system (1) further comprises one or more static mixer unit(s) (60) and an additional mixing of the molten expandable plastic material (110) by means of the static mixer unit(s) (60) is carried out, and wherein an melt filtration unit (30) is present and a filtering of the molten expandable plastic material (110) by means of the melt filtration unit (30) to form a filtered molten expandable material (120) is carried out prior to the granulation, extrusion, or injection molding.

2. The process of claim 1, wherein an expansion agent metering device (70) is absent from the system (1) and no addition of additional expansion agent (80) is made.

3. The process of either one of claim 1, wherein an expansion agent metering device (70) is present and an addition of additional expansion agent (80) by means of the expansion agent metering device (70) is carried out.

4. The process of claim 3, wherein the expansion agent metering device (70) is embodied so as to inject the additional expansion agent (80) into the extruder unit (10).

5. The process of claim 3, wherein a static mixer unit(s) (60) is / are present and additional mixing of the molten expandable plastic material (110) by means of the static mixer unit(s) (60) is carried out, and wherein the expansion agent metering device (70) is embodied so as to inject the additional expansion agent (80) into and / or before the static mixer unit(s) (60).

6. The process of claim 5, wherein at least two static mixer units (60) are present, wherein in a first static mixer unit (61) a dispersing step is carried out and which subjects the mixture to intensive mixing; and wherein in a second static mixer unit (62) a retaining step is carried out and which subjects the mixture to less intensive mixing than in the first static mixer unit (61).

7. The process of any one of claims 3 to 6, wherein the additional expansion agent (80) is injected and comprises an inert gas, a methylol, methyl formate, a pentane, a butane or their mixtures.

8. The process of any one of claims 1 to 7, wherein a masterbatch (200) is added to the extruder unit (10).

9. The process of any one of claims 1 to 8, wherein an additive (210) is added to the extruder unit (10).

10. The process of any one of claims 1 or 9 wherein the granulation unit (40) is an underwater or strand granulator.

Images