Use of styrenic polymers derived from depolymerized polystyrene in the production of foam materials and as melt flow modifiers

Abstract

A synthetic resin formulation can be made using a styrenic polymer produced by depolymerization of a polystyrene feedstock. In some embodiments, the polystyrene feedstock contains recycled polystyrene foam. In some embodiments, the styrenic polymer has a similar molecular weight as virgin polystyrene. In some embodiments, the styrenic polymer has a higher molecular weight and reduces the amount of virgin polystyrene needed for the synthetic resin formulation. In some embodiments, the styrenic polymer has a lower molecular weight and increases the amount of recycled polystyrene that can be used in the synthetic resin formulation by increasing and homogenizing the melt flow of the recycled polystyrene. The synthetic resin formulation can be used to manufacture foamed, extruded, and / or graphite polystyrene foam products, as well as rigid polystyrene and ABS products.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Patent Application No. 62 / 780,122, filed December 14, 2018, entitled "Uses for Styrenic Polymers Derived from Depolymerized Polystyrene". The entire contents of application 122 are incorporated herein by reference. Technical Field

[0003] This invention relates to a method for producing foamed or rigid polystyrene materials by incorporating styrene-based polymers, said styrene-based polymers being synthesized through the depolymerization of polystyrene. The invention also relates to the use of styrene-based polymers synthesized through the depolymerization of polystyrene as melt flow modifiers in polymer processing. Furthermore, polystyrene is non-biodegradable, leading to its accumulation in nature. Most polystyrene waste is either landfilled or incinerated. The former results in material loss and land wastage, while the latter leads to greenhouse gas emissions. Currently, only a small portion of polystyrene waste is recycled (less than 5% in North America and Europe) as secondary polymers.

[0004] One obstacle to using waste polystyrene as a raw material in the production of foamed polystyrene products is its wide range of sizing properties. Specifically, the broad molecular weight distribution and melt flow properties of waste polystyrene prevent or limit its ability to be incorporated into materials including extruded and expanded polystyrene foam products. Previous attempts to recycle waste polystyrene into new foam formulations have shown that the incorporation amount is limited to approximately 15% of the total weight of the foam formulation. Incorporation amounts greater than 15% can affect the properties of the final foam product, such as cell structure and compressive strength.

[0005] For example, certain fractions of styrene-based polymers produced by the depolymerization of polystyrene often possess specific structural or chemical properties, including but not limited to olefin content or longer aliphatic fractions near the chain ends, narrower molecular weight distribution, higher melt flow, and / or uniform melt flow rate. Furthermore, the high molecular weight fractions of styrene-based polymers produced by the depolymerization of polystyrene have a similar molecular weight distribution to that of the original polystyrene conventionally used in the production of extruded and expanded polystyrene foams.

[0006] The uniform properties of styrene polymers produced by depolymerizing polystyrene raw materials, namely narrowed molecular weight distribution and melt flow, make them suitable for foam formulations that can be used in a variety of applications, including but not limited to extruded polystyrene (XPS) insulation foam boards, XPS containers, XPS fillers and packaging materials, expanded polystyrene (EPS) fillers and packaging materials, and injection-molded or extruded acrylonitrile-butadiene-styrene (ABS).

[0007] Incorporating styrene-based polymers, derived from the depolymerization of polystyrene, into the manufacture of foam products can reduce the amount of virgin polystyrene required to produce polystyrene foam materials, and ultimately help reduce greenhouse gases, landfill waste, and the demand for styrene-based foam products that are entirely derived from fossil or virgin polystyrene. Summary of the Invention

[0008] In some embodiments, the synthetic resin formulation may comprise a styrene-based polymer obtained by depolymerizing a polystyrene feedstock, said polystyrene feedstock being derived from recycled polystyrene and / or virgin polystyrene. In some embodiments, the recycled polystyrene is polystyrene foam.

[0009] In some embodiments, the molecular weight of the styrene-based polymer is similar to that of the original polystyrene.

[0010] In some embodiments, the molecular weight of the styrene polymer is between 5,000 and 230,000 amu, and includes 5,000 amu and 230,000 amu. In some preferred embodiments, the molecular weight is between 20,000 amu and 170,000 amu, and includes 20,000 amu and 170,000 amu. In some more preferred embodiments, the molecular weight is between 35,000 amu and 130,000 amu, and includes 35,000 amu and 130,000 amu. In some most preferred embodiments, the molecular weight is between 45,000 amu and 95,000 amu, and includes 45,000 amu and 95,000 amu.

[0011] In some embodiments, the melt flow index of the styrene-based polymer is between 1 and 1000 g / 10 min, including 1 g / 10 min and 1000 g / 10 min. In some preferred embodiments, the melt flow index of the styrene-based polymer is between 50 and 750 g / 10 min, including 50 g / 10 min and 750 g / 10 min. In some preferred embodiments, the melt flow index of the styrene-based polymer is between 75 and 650 g / 10 min, including 75 g / 10 min and 650 g / 10 min. In some preferred embodiments, the melt flow index of the styrene-based polymer is between 100 and 550 g / 10 min, including 100 g / 10 min and 550 g / 10 min. In some preferred embodiments, the melt flow index of the styrene-based polymer is between 110 and 500 g / 10 min, including 110 g / 10 min and 500 g / 10 min.

[0012] In some embodiments, the styrene-based polymer can reduce the amount of virgin polystyrene required for the synthetic resin formulation. In some embodiments, the styrene-based resin may also contain virgin polystyrene. In some embodiments, the styrene-based polymer constitutes at least 20% by weight of the synthetic resin formulation.

[0013] In some embodiments, the styrene polymer has a molecular weight between 10,000 and 150,000 amu, including 10,000 amu and 150,000 amu, and a melt flow index between 14 and 750 g / min, including 14 g / min and 750 g / min.

[0014] In some embodiments, the amount of recycled polystyrene can be increased by improving and homogenizing the melt flow of the recycled polystyrene that can be used in synthetic resin formulations. In some embodiments, the styrene-based polymer accounts for 0.5-20% by weight of the synthetic resin formulation.

[0015] In some embodiments, the styrene polymer can reduce the density of the resin formulation used in the foam product compared to a resin formulation without the styrene polymer, thereby reducing the total weight of the product.

[0016] In some embodiments, the styrene polymer can reduce extruder torque and die pressure compared to resin formulations without the styrene polymer, thereby increasing the achievable yield of foam products.

[0017] Various embodiments of the synthetic resin formulation can be used to manufacture foamed, extruded, and / or graphite polystyrene foam products. In some embodiments, the extruded polystyrene foam product is a thermal insulation material or a filler material. In some embodiments, the foamed polystyrene foam product is concrete.

[0018] In some embodiments, the synthetic resin formulation can be used to manufacture rigid polystyrene products, such as containers.

[0019] In some embodiments, the synthetic resin formulation can be used to manufacture injection-molded or extruded ABS parts, such as automotive trim components. Attached Figure Description

[0020] Figure 1 A flowchart illustrating the process of processing polystyrene materials to produce styrene-based polymers.

[0021] Figure 2 A flowchart illustrating the process of generating foam formulations using styrene-based polymers.

[0022] Figure 3 This is a graph showing the heat flow of the high molecular weight portion of styrene-based polymers, namely polymer A, obtained by depolymerizing waste polystyrene foam.

[0023] Figure 4 This is a graph showing the heat flow of the low molecular weight fraction of styrene-based polymers, namely polymer B, obtained by depolymerizing waste polystyrene foam.

[0024] Figure 5 This is a graph showing the heat flow of the low molecular weight fraction of styrene-based polymers, namely polymer C, obtained by depolymerization of waste polystyrene foam.

[0025] Figure 6 This is a graph showing the heat flow of the low molecular weight fraction of styrene-based polymers, namely polymer D, obtained by depolymerization of waste polystyrene foam.

[0026] Figure 7A Photograph of extruded polystyrene containing 99.5% virgin polystyrene and 0.5% talc.

[0027] Figure 7B Photograph of extruded polystyrene containing 74.5% virgin polystyrene / 25% recycled polystyrene / 0.5% talc.

[0028] Figure 7C Photograph of extruded polystyrene containing 72.5% virgin polystyrene, 25% recycled polystyrene, 0.5% talc, and 2% styrene-based polymers derived from the depolymerization of waste polystyrene.

[0029] Figure 7D Photograph of extruded polystyrene containing 70.5% virgin polystyrene, 25% recycled polystyrene, 0.5% talc, and 4% styrene-based polymers derived from the depolymerization of waste polystyrene.

[0030] Figure 7E Photograph of extruded polystyrene containing 68.5% virgin polystyrene, 25% recycled polystyrene, 0.5% talc, and 6% styrene-based polymers derived from the depolymerization of waste polystyrene.

[0031] Figure 7F Photograph of extruded polystyrene containing 64.5% virgin polystyrene, 25% recycled polystyrene, 0.5% talc, and 10% styrene-based polymers derived from the depolymerization of waste polystyrene.

[0032] Figure 8A This is a scanning electron microscope image of extruded polystyrene produced from virgin polystyrene, containing 0% styrene-based polymers derived from waste polystyrene.

[0033] Figure 8B This is a scanning electron microscope image of extruded polystyrene produced from virgin polystyrene, containing 2% styrene-based polymers derived from waste polystyrene.

[0034] Figure 8C This is a scanning electron microscope image of extruded polystyrene produced from virgin polystyrene, containing 4% styrene-based polymers derived from waste polystyrene.

[0035] Figure 8D This is a scanning electron microscope image of extruded polystyrene produced from virgin polystyrene, containing 6% styrene-based polymers derived from waste polystyrene.

[0036] Figure 8E This is a scanning electron microscope image of extruded polystyrene produced from virgin polystyrene, containing 10% styrene-based polymers derived from waste polystyrene.

[0037] Figure 9 A graph illustrating the effect of styrene polymers on the melt flow of virgin and recycled polystyrene feedstocks.

[0038] Figure 10 A graph illustrating the effect of styrene polymers on the melt flow of different recycled polystyrene feedstocks.

[0039] Figure 11 A graph illustrating the effect of styrene-based polymers on the melt flow of the original acrylonitrile-butadiene-styrene (ABS) feedstock. Detailed Implementation

[0040] Methods for converting polystyrene raw materials into styrene polymers and their applications are discussed in international application PCT / CA2017 / 051166 entitled “Reactor for Treating Polystyrene Material” and U.S. application 62 / 678,780 entitled “Uses of Styrenic Polymers Derived Through Depolymerized Polystyrene”, the entire contents of which are incorporated herein by reference.

[0041] This disclosure in particular teaches a method for producing foam resin formulations using styrene-based polymers.

[0042] In some embodiments of the method for producing foam resin formulations using styrene-based polymers, polystyrene material is recycled. Converting polystyrene material into styrene-based polymers may include: selecting solid polystyrene material; heating the solid polystyrene material in an extruder to produce molten polystyrene material; filtering the molten polystyrene material; placing the molten polystyrene material in a reactor to produce styrene-based polymers through a chemical depolymerization process; cooling the styrene-based polymers; and / or purifying the styrene-based polymers.

[0043] In some embodiments, styrene polymers may be modified to add additional active sites, such as acrylates, ketones, esters, aldehydes, carboxylic acids, alcohols, and amines. These active sites can be used for functionalization purposes. In some embodiments, a variety of monomers and / or copolymers, such as, but not limited to, acids, alcohols, acetates, acrylates, ketones, esters, aldehydes, amines, and olefins such as hexene, may be grafted onto the depolymerization product to improve compatibility and / or increase functionality.

[0044] In some implementations, to improve compatibility and / or increase functionality, multiple monomers and / or copolymers are grafted onto the substrate via olefin fingerprints and / or via aromatic functionality. Grafting can be carried out, in particular, in a reactor, together with a cooled feed stream, and / or in a separate vessel.

[0045] In some embodiments, the polystyrene material may be dissolved in a solvent prior to depolymerization to adjust the viscosity of the polymer at different temperatures. In some embodiments, the polystyrene is dissolved using an organic solvent such as toluene, xylene, methyl isopropylbenzene, or terpinene before depolymerization in a reaction bed / vessel. In some embodiments, the desired product may be separated by separation or extraction, and the solvent may be recovered.

[0046] In at least some implementations, no solvent is required.

[0047] In some embodiments, the solid polystyrene material is recycled polystyrene. In some embodiments, the recycled polystyrene is granules made from recycled polystyrene foam and / or rigid polystyrene. Suitable waste polystyrene materials include, but are not limited to, mixed polystyrene waste, such as foamed and / or extruded polystyrene foam, and / or rigid products such as foamed food containers, or packaging products. Mixed polystyrene waste may include different melt flows and molecular weights. In some embodiments, the waste polystyrene material feed contains up to 25% of materials other than polystyrene material, based on the total weight of the waste polystyrene material feed.

[0048] In some implementation schemes, virgin polystyrene may also be used as a raw material.

[0049] In some embodiments, the polymer feed is one or a combination of virgin polystyrene and / or post-industrial and / or post-consumption waste polystyrene.

[0050] In some embodiments, it is desirable to convert the polymer feedstock into a lower molecular weight polymer with improved melt flow and olefin content. In some embodiments, the conversion is influenced by heating the polystyrene feedstock to generate molten polystyrene material, and then contacting the molten polystyrene material with a catalyst material in a reaction zone at a temperature set between 200°C and 400°C, preferably between 225°C and 375°C, and including 225°C and 375°C. In some embodiments, a catalyst is not required.

[0051] The molecular weight, polydispersity, glass transition, melt flow, and / or olefin content resulting from depolymerization depend on the residence time of the polystyrene material in the reaction zone.

[0052] In some embodiments, the depolymerization process utilizes a catalyst such as [Fe-Cu-Mo-P] / Al2O3, zeolite, or other alumina-supported systems, and / or thermal depolymerization. In some embodiments, the catalyst may be contained in a permeable container. In some embodiments, the catalyst may contain iron, copper, molybdenum, phosphorus, and / or alumina.

[0053] In some implementations, the purification of styrene polymers utilizes flash separation, absorption beds, clay polishing, and / or membrane evaporators.

[0054] Figure 1Process 1 for processing polystyrene material is described. Process 1 can be operated in batches or as a continuous process. Parameters of Process 1, including but not limited to temperature, polystyrene flow rate, monomers / copolymers grafted during the reaction and / or modification stages, and / or the total number of preheating, reaction, or cooling sections, can be modified to produce styrene polymers with molecular weights between 5,000 and 230,000 amu, including 5,000 amu and 230,000 amu. In some specific embodiments, for example when the resulting styrene polymer is intended for use in foam formulations, the styrene polymer may have different molecular weights between 40,000 and 200,000 amu, including 40,000 amu and 200,000 amu.

[0055] In some embodiments, during the material selection stage 10, the polystyrene feed is sorted / selected and / or prepared for processing. In some embodiments, the feed may contain up to 25% of polyolefins PP, PE, PET, EVA, EVOH, and lower levels of undesirable additives or polymers, such as nylon, rubber, PVC, ash, fillers, pigments, stabilizers, gravel, and / or other unknown particles.

[0056] In some embodiments, the average molecular weight of the polystyrene feedstock is between 150,000 and 500,000 amu, including both 150,000 amu and 500,000 amu. In some embodiments, the average molecular weight of the polystyrene feedstock is between 200,000 and 300,000 amu, including both 200,000 amu and 300,000 amu.

[0057] In some embodiments, the materials selected in material selection phase 10 include recycled polystyrene. In other or similar embodiments, the materials selected in material selection phase 10 include recycled polystyrene and / or virgin polystyrene.

[0058] In some implementations, the materials selected in the material selection phase 10 include waste polystyrene foam.

[0059] In some embodiments, during solvent addition stage 20, the polystyrene is dissolved using a solvent such as toluene, xylene, methyl isopropylbenzene, or terpinene before depolymerization within the reaction bed / vessel. In some embodiments, the desired product can be separated by separation or extraction, and the solvent can be recovered.

[0060] In some embodiments, the material selected in the material selection stage 10 may be heated in the extruder in the heating stage 30 and subjected to a pre-filtration process 40. In some embodiments, the extruder is used to increase the temperature and / or pressure of the fed polystyrene and to control the flow rate of the polystyrene. In some embodiments, the extruder is supplemented or completely replaced by a pump / heat exchanger combination.

[0061] In some embodiments, the molten polystyrene material originates from a polystyrene material feed that is heated to produce molten polystyrene material. In some embodiments, the polystyrene material feed comprises initial raw polystyrene particles. The raw particles may include a variety of molecular weights and melt flows.

[0062] In some embodiments, the pre-filtration process 40 may employ screen changers and filter beds, as well as other filtration technologies / devices, to remove contaminants from the heated material and purify the heated material. In some embodiments, the resulting filter material is then transferred to an optional preheating stage 50, which brings the filter material to a higher temperature before it enters the reaction stage 60. In some embodiments, the preheating stage 50 may particularly employ static and / or dynamic mixers and heat exchangers, such as internal fins and heat pipes.

[0063] In some embodiments, the material undergoes depolymerization in reaction stage 60. This depolymerization can be a purely thermal reaction and / or it can utilize a catalyst. Depending on the raw materials and the desired styrene-based polymer, depolymerization can be used to slightly or drastically reduce the molecular weight of the raw materials. In some embodiments, the catalyst used is a zeolite or alumina supported system or a combination of both. In some embodiments, the catalyst is a [Fe-Cu-Mo-P] / Al2O3 prepared by combining a ferrous-copper complex with an alumina or zeolite support and reacting it with an acid comprising both metals and nonmetals. Other suitable catalyst materials include zeolites, mesoporous silica, hydrogen-form mordenite, and alumina. The system can also be operated without a catalyst and produce a lower molecular weight polymer through thermal degradation.

[0064] In some implementations, the depolymerization of the polymer material is carried out by a catalytic process, a thermal process, using a free radical initiator, and / or using radiation.

[0065] In some embodiments, reaction stage 60 may employ various technologies / apparatus, particularly including fixed-bed, horizontal and / or vertical reactors, and / or static mixers. In some embodiments, reaction stage 60 employs multiple reactors and / or reactors divided into multiple sections.

[0066] In some embodiments, after reaction stage 60, the depolymerized material proceeds to an optional modification stage 70. In at least some embodiments, modification stage 70 involves grafting various monomers and / or copolymers, such as, but not limited to, acids, alcohols, acetates, and / or olefins such as hexene, onto the depolymerized product.

[0067] In some embodiments, cooling stage 80 may employ heat exchangers and other technologies / devices to reduce the styrene polymer to a usable temperature before proceeding to an optional purification stage 90. In some embodiments, the styrene polymer is washed / purified by methods such as nitrogen stripping prior to cooling stage 80.

[0068] Optional purification stage 90 involves the refining and / or purification of styrene-based polymers. Techniques / apparatus that can be used in purification stage 90 include, but are not limited to, flash separation, absorption beds, clay polishing, distillation, vacuum distillation, and filtration to remove solvents, oils, colorants, ash, inorganic matter, and coke. In some embodiments, a thin-film or scraped-film evaporator is used to remove gases, oils, and / or greases, and / or lower molecular weight functionalized polymers from the styrene-based polymers. In some embodiments, oils, gases, and lower molecular weight functionalized polymers may be sequentially combusted to facilitate the operation of each stage of process 1. In some embodiments, the desired product may be separated by separation or extraction, and the solvent may be recovered.

[0069] Process 1 ends at the finished product stage 100, where the initial raw materials selected in the material selection stage 10 have been transformed into a styrene-based polymer. In at least some embodiments, the styrene-based polymer does not require further processing and / or refining. In other embodiments, the styrene-based polymer produced in the finished product stage 100 requires further modification.

[0070] In some embodiments, the resulting depolymerization product material includes monomers (styrene), aromatic solvents, polycyclic aromatic substances, oils, and / or functionalized polymers with lower molecular weights, such as those with increased olefin content.

[0071] In some embodiments, the styrene-based polymer has an average molecular weight between 5,000 and 230,000 amu, including both 5,000 and 230,000 amu, and a melt flow rate between 1 and 1,000 g / 10 min, including both 1 g / 10 min and 1,000 g / 10 min (as determined by ASTM D1238). In some embodiments, the glass transition temperature of the styrene-based polymer is between 30 and 115 °C, including both 30 and 115 °C.

[0072] In some embodiments, the molecular weight of the styrene polymer is between 5,000 and 230,000 amu, including 5,000 amu and 230,000 amu. In some preferred embodiments, the molecular weight is between 20,000 amu and 170,000 amu, including 20,000 amu and 170,000 amu. In some more preferred embodiments, the molecular weight is between 35,000 amu and 130,000 amu, including 35,000 amu and 130,000 amu. In some most preferred embodiments, the molecular weight is between 45,000 amu and 95,000 amu, including 45,000 amu and 95,000 amu.

[0073] In some embodiments, the melt flow index of the styrene-based polymer is between 1 and 1000 g / 10 min, including 1 g / 10 min and 1000 g / 10 min. In some preferred embodiments, the melt flow index of the styrene-based polymer is between 50 and 750 g / 10 min, including 50 g / 10 min and 750 g / 10 min. In some preferred embodiments, the melt flow index of the styrene-based polymer is between 75 and 650 g / 10 min, including 75 g / 10 min and 650 g / 10 min. In some preferred embodiments, the melt flow index of the styrene-based polymer is between 100 and 550 g / 10 min, including 100 g / 10 min and 550 g / 10 min. In some preferred embodiments, the melt flow index of the styrene-based polymer is between 110 and 500 g / 10 min, including 110 g / 10 min and 500 g / 10 min. In some embodiments, the resulting styrene polymer has a molecular weight range of 40,000-200,000 amu and includes 40,000 amu and 200,000 amu, and a melt flow range of 1-750 g / 10 min and includes 1 g / 10 min and 750 g / 10 min.

[0074] In some embodiments, the viscosity of the styrene polymer, measured at 250°C, is between 100 and 150,000 cps, including 100 cps and 150,000 cps. In some preferred embodiments, the viscosity, measured at 250°C, is between 1,000 cps and 125,000 cps. In other preferred embodiments, the viscosity, measured at 250°C, is between 5,000 cps and 100,000 cps.

[0075] In some embodiments, the viscosity of the styrene polymer, measured at 225°C, is between 1,000 and 150,000 cps, including 1,000 cps and 150,000 cps. In some preferred embodiments, the viscosity, measured at 225°C, is between 1,500 cps and 120,000 cps. In other preferred embodiments, the viscosity, measured at 225°C, is between 2,000 cps and 100,000 cps.

[0076] In some embodiments, the melt flow range of the resulting styrene-based polymer can be greater than 50 g / 10 min. In some preferred embodiments, the melt flow range of the resulting styrene-based polymer can be between 50 and 500 g / 10 min, including both 50 g / 10 min and 500 g / 10 min.

[0077] In some embodiments, the resulting styrene-based polymers can be used to produce EPS, XPS, and / or graphite polystyrene (GPS) foams. Polystyrene foams can be used in a variety of applications, including but not limited to XPS insulation foam boards, XPS containers, XPS filler and packaging materials, EPS filler and packaging materials, insulating concrete formwork, interior trim, ceilings, and other roofing, wall, floor, basement, and structural insulation applications.

[0078] Styrene-based polymers derived from depolymerized polystyrene can be used to manufacture polystyrene foam products. In some embodiments, this is attributed to the fact that the high molecular weight fraction of the styrene-based polymers has a more uniform molecular weight distribution and melt flow properties compared to unmodified, i.e., non-depolymerized waste polystyrene. In some embodiments, the styrene-based polymers derived from depolymerized polystyrene have properties comparable to virgin polystyrene, including but not limited to molecular weight, molecular weight distribution (dispersion), and melt flow index.

[0079] In some implementations, a higher percentage of styrene polymers derived from the depolymerization of waste polystyrene foam can be used in the foam resin formulation compared to the percentage of unmodified waste polystyrene foam, while maintaining the desired properties of the final foam product, such as density, cell structure, and compressive strength.

[0080] In some implementations, the styrene polymer portion derived from the depolymerization of waste polystyrene foam can be used to improve and / or homogenize the melt flow of recycled polystyrene feedstock, which in turn increases the amount of recycled polystyrene available for use in foam resin formulations.

[0081] In some implementations, the styrene polymer portion derived from the depolymerization of waste polystyrene foam can be used to reduce the density of the foam product.

[0082] In some implementations, the styrene polymer fraction derived from the depolymerization of waste polystyrene foam can be used to reduce extruder torque and die pressure, which in turn can increase the yield of foam products.

[0083] In some embodiments, the resulting styrene polymers can be used to produce rigid polystyrene products, including but not limited to hangers, lids, toys, household appliances, garden pots, automotive parts, and containers.

[0084] In some embodiments, the synthetic resin formulation can be used to manufacture injection-molded or extruded ABS parts, such as automotive trim components.

[0085] Various parameters of Process 1 can be modified, including but not limited to temperature, pressure, polystyrene flow rate, catalyst selection, monomers / copolymers grafted during the reaction and / or modification stages, and the total number and / or run time of preheating, reaction and / or cooling sections, to maximize the yield of the styrene polymer portion that can be used in foam resin formulations.

[0086] In some embodiments, EPS and XPS foams can be produced using styrene-based polymers obtained through the depolymerization of virgin polystyrene and / or recycled polystyrene. In some preferred embodiments, styrene-based polymers for manufacturing polystyrene foam can be produced through the depolymerization of waste polystyrene foam.

[0087] In some implementations, the parameters of process 1 can be optimized to improve the compatibility of styrene polymers with foam resin formulations, thereby allowing the use of a higher percentage of styrene polymers in the formulation. For example, various reaction conditions of process 1 can be modified to produce styrene polymers with optimal or preferred molecular weight distribution and melt flow properties suitable for incorporation into foam resin formulations.

[0088] In some implementations, styrene-based polymers can be blended with virgin polystyrene and / or waste polystyrene foam to produce foam products.

[0089] In some embodiments, the lower molecular weight fraction of the styrene polymer, i.e., styrene polymers with a molecular weight less than 100,000 amu and a melt flow greater than 10 g / min, can be used as an additive to increase the amount of recycled polystyrene by improving and homogenizing the variable, low melt flow of the recycled polystyrene in the feed. The recycled polystyrene can be used in polystyrene synthetic resin formulations, foam formulations, or other extruded polystyrene products. In some embodiments, the lower molecular weight fraction of the styrene polymer can be 0.5-20% by weight of the formulation used to produce polystyrene foam or other extruded polystyrene products.

[0090] Figure 2 This demonstrates the use of depolymerization processes (e.g.) Figure 1 The process 200 involves using a styrene-based polymer product to generate a foam resin formulation. First, a styrene-based polymer product is selected in a styrene-based polymer selection stage 210, and then added in a formulation stage 220 to generate a foam resin.

[0091] Illustrative Examples

[0092] In an illustrative embodiment of the method under discussion, waste polystyrene foam is used to generate a series of depolymerized styrene polymers: polymer A, polymer B, polymer C, and polymer D.

[0093] Polymer A is the high molecular weight fraction of styrene-based polymer products, with a molecular weight distribution of 175,000-225,000 amu. Polymers B and C are lower molecular weight styrene-based polymer products, with a molecular weight distribution of 50,000-75,000. Polymer D has a molecular weight of approximately 65,000.

[0094] The melt flow index and differential scanning calorimetry (DSC) values ​​for polymers A, B, C, and D are listed in Table 1.

[0095] Table 1: Properties of depolymerized styrene polymers

[0096]

[0097] The heat flux data of polymers A, B, C, and D are respectively depicted on Figure 3 , Figure 4 , Figure 5 and Figure 6 The curve in the graph.

[0098] These exemplary depolystyrene polymers were then mixed with other components (see Tables 2, 3, 4, and 6) to produce a variety of formulations, which were then tested to demonstrate their various properties.

[0099] Table 2: Properties of recycled PS

[0100]

[0101] Table 3: Sample Components

[0102] Element Level / Type AmStyEA3130 Original general-purpose polystyrene Total535B Original general-purpose polystyrene SigmaPS Original general-purpose polystyrene IneosTerluranGP-22 Original acrylonitrile butadiene styrene Polymer A Depolymerized styrene polymers Polymer B Depolymerized styrene polymers Polymer C Depolymerized styrene polymers Polymer D Depolymerized styrene polymers PS-A recycling Waste polystyrene foam PS-B recycling Waste polystyrene Recycling PS-C Waste polystyrene Recycle PS-D Waste polystyrene

[0103] Examples of foaming using high molecular weight styrene polymers

[0104] As shown in Table 4, foam resin formulations prepared from polystyrene raw material (recycled PS-A) and styrene polymers (polymer A) are compared with control foam resin formulations prepared using virgin polystyrene EA3130 (a conventional polystyrene raw material used in foam production).

[0105] Preliminary tests were conducted on formulations 1-3 (and control I) to determine whether depolymerized polystyrene (at least a certain percentage) could be used to generate foam.

[0106] To determine whether using polystyrene feedstock that has undergone depolymerization to form styrene-based polymers would affect foam production, polymer A was compared with untreated waste polystyrene foam recycled PS-A that had not undergone depolymerization process 1. The molecular weight distribution of recycled PS-A was approximately 225,000–250,000 amu.

[0107] Formulations 1-3 and control I were mixed with 0.5 pph foaming agent FP-40 and subjected to standard foam extrusion. The extruder conditions for each formulation are shown in Table 5.

[0108] Compared to Control I, the extruder conditions for Formulations 1 and 2 were within a suitable range, indicating that foam production using styrene-based polymers does not require additional energy input or increase equipment strain during extrusion. These data suggest that foam production using styrene-based polymers can be carried out under existing manufacturing conditions without requiring modifications to production equipment.

[0109] Table 4: Composition of Foaming Agents

[0110]

[0111]

[0112]

[0113] Table 5: Extruder conditions during foam production

[0114]

[0115]

[0116]

[0117] Resin foam formulations are also made into granules. The success of each resin formulation in generating foam depends on the ability of each resulting granule to float in water (Table 6), as this represents the proper transformation of non-foamed polystyrene with a density greater than water into polystyrene foam with a density less than water.

[0118] Table 6: Density observation of resin formulations

[0119]

[0120] As shown in Table 6, the granules produced from resin formed from 100% waste polystyrene foam (Formulation 3) sank, indicating that a functional foam composition was not achieved.

[0121] Granules produced from resin formed from 100% styrene-based polymers (Formulation 2) showed settling (3 out of 4 replicates) and floating (1 out of 4 replicates). This result demonstrates the feasibility of producing foam materials using 100% or at least 50% styrene-based polymers derived from the depolymerization of waste polystyrene.

[0122] Granule flotation produced from a resin formed from 50% virgin polystyrene and 50% polymer A (formulation 1) indicates the achievement of a functional foam composition.

[0123] The data also supports the view that, in at least some implementations, the depolymerized styrene polymers enable the final foam product to have a lower density, resulting in greater buoyancy.

[0124] Previous attempts to produce foam using 50% virgin polystyrene and 50% recycled polystyrene foam were unsuccessful. The ability of Formulation 1, a composition of 50% virgin polystyrene and 50% polymer A, to produce functional foam materials demonstrates that styrene polymers derived from the depolymerization of waste polystyrene possess unique properties that are advantageous for foam production and are lacking in unmodified, i.e., non-depolymerized waste polystyrene foam.

[0125] Examples of foaming using low molecular weight styrene polymers

[0126] Foaming tests were also completed, in which lower molecular weight styrene polymers, namely polymers B and C, derived from the depolymerization of waste polystyrene, were used as additives with low concentrations in the entire formulation.

[0127] As shown in Table 4, foam resin formulations prepared from recycled PS-B and styrene polymers (polymer B and polymer C) are compared with control foam resin formulations prepared using virgin polystyrene 535B (a conventional polystyrene raw material used in foam production).

[0128] Formulation 4-57 was mixed with foaming agent HCFO-1233zd(E) and subjected to standard foam extrusion. Formulation 4-57 used 0.5% talc as a nucleating agent (through 20% masterbatch). Formulation 4-57 was successfully used to obtain foam products in all cases.

[0129] The extruder conditions and key properties (foam density and feed rate) for each formulation are shown in Table 5.

[0130] Extruder conditions for formulations containing polymer B or polymer C resulted in reduced die pressure and extruder torque. These values, compared to the control formulation, were within a suitable range, indicating that foam production using styrene-based polymers requires less energy input and reduces equipment strain during extrusion.

[0131] The reduction in extruder torque and die pressure indicates that polymers derived from the depolymerization of waste polystyrene can increase the yield of XPS foam production.

[0132] These data indicate that foam production using styrene-based polymers can be carried out under existing manufacturing conditions without requiring modifications to production equipment.

[0133] Figure 7A To show a photograph of foam made from virgin polystyrene, which contains 0% styrene-based polymers produced from waste polystyrene (Formulation 4).

[0134] Figure 7B To show a photograph of foam made from virgin polystyrene and recycled polystyrene, in which there is 0% styrene-based polymer produced from waste polystyrene (Formulation 10).

[0135] Figure 7C To show a photograph of foam made from virgin polystyrene and recycled polystyrene, in which 2% of styrene-based polymers (Formulation 11) are produced from waste polystyrene.

[0136] Figure 7D To show a photograph of foam made from virgin polystyrene and recycled polystyrene, in which 4% of styrene-based polymers (Formulation 12) are produced from waste polystyrene.

[0137] Figure 7E To show a photograph of foam made from virgin polystyrene and recycled polystyrene, in which 6% of styrene-based polymers (Formulation 13) are produced from waste polystyrene.

[0138] Figure 7F To show a photograph of foam made from virgin polystyrene and recycled polystyrene, in which 10% of styrene-based polymers (Formulation 14) are produced from waste polystyrene.

[0139] As shown in Table 7, foams produced containing polymer B or polymer C typically have a lower density compared to the control.

[0140] Samples of the resin foam formulation were taken and scanned using scanning electron microscopy to measure foam integrity and open-cell content. Foam integrity and open-cell content were not adversely affected by the presence of styrene-based polymers derived from the depolymerization of waste polystyrene.

[0141] Figure 8A To show a scanning electron micrograph of foam made from virgin polystyrene, which contains 0% styrene-based polymers produced from waste polystyrene (Formulation 4).

[0142] Figure 8B To show a scanning electron micrograph of foam made from virgin polystyrene, which contains 2% styrene-based polymers produced from waste polystyrene (Formulation 5).

[0143] Figure 8C To show a scanning electron micrograph of foam made from virgin polystyrene, which contains 4% styrene-based polymers produced from waste polystyrene (Formulation 6).

[0144] Figure 8D To show a scanning electron micrograph of foam made from virgin polystyrene, which contains 6% styrene-based polymers produced from waste polystyrene (Formulation 7).

[0145] Figure 8E To show a scanning electron micrograph of foam made from virgin polystyrene, which contains 10% styrene-based polymers produced from waste polystyrene (Formulation 8).

[0146] These data indicate that styrene-based polymers derived from the depolymerization of waste polystyrene possess unique properties that are advantageous for use in foam production. These properties include density modifiers and yield modifiers.

[0147] Examples of styrene-based polymers as melt flow modifiers

[0148] To determine whether the low molecular weight fraction of styrene polymers could be used to improve the melt flow of virgin or recycled polystyrene feedstocks, styrene polymers, either polymer C or polymer D, with a molecular weight of approximately 65,000 amu, were added to the virgin or recycled polystyrene feedstocks, as shown in Table 7. The melt flow of each styrene polymer-polystyrene resin blend was then tested and compared to untreated virgin or recycled polystyrene (PS) feedstocks. The melt flow index of each blend is also listed in Table 7.

[0149] Table 7: Composition of Resin Formulations and Melt Flow Index of the Obtained Blends

[0150]

[0151]

[0152] Control II was used as a control for formulations 58-62; Control III was used as a control for formulations 63-67; Control IV was used as a control for formulations 68-72; Control V was used as a control for formulations 73-75; and Control VI was used as a control for formulations 76-80.

[0153] As shown in Table 7, the melt flow index of both the original polystyrene raw material and the recycled polystyrene raw material increases with the increase of the percentage of styrene polymers.

[0154] Figure 9 A graph showing the percentage change in melt flow index of resin blends Control II, Control III, and Formulation 58-67.

[0155] Figure 10 A graph showing the percentage change in melt flow index of resin blends control IV, control V, and formulation 68-75.

[0156] Figure 11 A graph showing the percentage change in melt flow index of resin blend control VI and formulation 76-80.

[0157] These data indicate that the low molecular weight fraction of styrene polymers can be used to improve the melt flow of virgin polystyrene, recycled polystyrene, and ABS. Improving the melt flow of recycled polystyrene can enable it for applications such as, but not limited to, synthetic resin formulations, foam resin formulations, and formulations of rigid polystyrene and ABS products.

[0158] In summary, these data indicate that styrene polymers derived from the depolymerization of waste polystyrene possess unique properties advantageous for use in synthetic resin formulations. These unique properties are acquired during the depolymerization process and, compared to unmodified recycled polystyrene / waste polystyrene, include at least a narrower molecular weight distribution and better melt flow.

[0159] While specific elements, embodiments, and applications of the invention have been shown and described, it should be understood that the invention is not limited thereto, as modifications can be made without departing from the scope of this disclosure, particularly in light of the foregoing teachings. Furthermore, all claims are incorporated herein by reference in the description of preferred embodiments.

Claims

1. A polystyrene foam product comprising: A synthetic resin formulation comprising a styrene-based polymer obtained by depolymerization of a polystyrene raw material. in, The melt flow index of the styrene polymer is between 50 and 750 g / 10 min, including 50 g / 10 min and 750 g / 10 min, and the melt flow index is determined by ASTM D1238. The polystyrene raw material mentioned above includes recycled polystyrene; The styrene polymers therein have a molecular weight of 50,000-75,000 amu; and The styrene polymer thereon is 0.5-20% by weight of the synthetic resin formulation.

2. The polystyrene foam product according to claim 1, wherein the melt flow index is between 110 and 500 g / 10 min, including 110 g / 10 min and 500 g / 10 min, and the melt flow index is determined by ASTM D1238.

3. The polystyrene foam product according to claim 1, wherein the amount of recycled polystyrene is increased by improving and homogenizing the melt flow of recycled polystyrene that can be used in the synthetic resin formulation.

4. The polystyrene foam product according to claim 1, wherein the styrene polymer improves the melt flow of PS and / or ABS plastics.

5. The polystyrene foam product according to claim 1, wherein the styrene polymer increases the extrusion yield of PS and / or ABS plastics.

6. The polystyrene foam product according to claim 1, wherein the polystyrene foam product is an extruded polystyrene foam product.

7. The polystyrene foam product according to claim 6, wherein the extruded polystyrene foam product is a thermal insulation material.

8. The polystyrene foam product according to claim 6, wherein the extruded polystyrene foam product is a filler material.

9. The polystyrene foam product according to claim 1, wherein the polystyrene foam product is a expanded polystyrene foam product.

10. The polystyrene foam product according to claim 9, wherein the expanded polystyrene foam product is concrete.

11. The polystyrene foam product according to claim 1, wherein the synthetic resin formulation is used to manufacture the graphite polystyrene foam product.

12. The polystyrene foam product according to claim 1, wherein the polystyrene raw material comprises virgin polystyrene.

13. The polystyrene foam product of claim 1, wherein the styrene polymer reduces the amount of virgin polystyrene required for the polystyrene foam product.

14. The polystyrene foam product according to claim 1, wherein the synthetic resin formulation is used to manufacture injection-molded or extruded ABS products.

15. The polystyrene foam product according to claim 1, wherein the polystyrene foam product is a rigid polystyrene product.

16. The polystyrene foam product according to claim 15, wherein the rigid polystyrene product is a container.

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