Styrene copolymers derived from depolymerized polystyrene for use in the manufacture of foam materials and as melt flow modifiers.

Abstract

To reduce the amount of virgin polystyrene required to manufacture polystyrene foam material. [Solution] A synthetic resin compound containing a styrene-based polymer produced by the depolymerization of polystyrene feedstock.

Description

Technical Field

[0001] Cross - reference to Related Applications This application claims the priority of U.S. Application Serial No. 62 / 780,122, filed on December 14, 2018, entitled "Uses for Styrenic Polymers Derived from Depolymerized Polystyrene". The entire content of the '122 application is incorporated herein by reference.

[0002] Technical Field of the Invention The present invention relates to a method for manufacturing a foam or a rigid polystyrene material incorporating a styrenic polymer synthesized by depolymerization of polystyrene. The present invention also relates to the use as a melt flow regulator in polymer processing of a styrenic polymer synthesized by depolymerization of polystyrene. Further, since polystyrene is not biodegradable, it accumulates in nature. Most of the polystyrene waste is either landfilled or incinerated. The former leads to loss of materials and waste of land, and the latter leads to emissions of greenhouse gases. Currently, only a very small part (less than 5% in North America and Europe) of the polystyrene waste is recycled as a secondary polymer.

Background Art

[0003] One of the barriers to using polystyrene waste as a starting material for expanded polystyrene products is its wide range of usability properties. Specifically, the broad distribution of molecular weight and melt flow characteristics of waste polystyrene hinders or limits its ability to be incorporated into materials such as extruded polystyrene foam products and expanded polystyrene foam products. In previous attempts to recycle waste polystyrene into new foam formulations, the incorporation of waste polystyrene has been limited to approximately 15% of the total mass of the blowing agent. Incorporation exceeding 15% impairs the properties of the final foam product, such as cellular structure and compressive strength.

[0004] For example, some fractions of styrene polymers produced by the depolymerization of polystyrene often exhibit certain structural or chemical properties, such as (but not limited to) olefin content or long aliphatic moieties near the end of the chain, a narrow molecular weight distribution, high melt flow, and / or a uniform melt flow rate. Furthermore, high molecular weight fractions of styrene polymers produced by the depolymerization of polystyrene have a molecular weight distribution similar to that of virgin polystyrene, which has been conventionally used in the production of extruded and bead-formed polystyrene foams.

[0005] The uniform properties of styrene polymers produced by the depolymerization of polystyrene feedstock, namely their narrow molecular weight distribution and melt flow, make them suitable for use in foam formulations for a variety of applications, including but not limited to extruded polystyrene (XPS) insulating foam boards, XPS containers, XPS packaging and wrapping materials, bead-molded polystyrene (EPS) packaging and wrapping materials, and injection-molded or extruded acrylonitrile-butadiene-styrene (ABS). [Overview of the project] [Problems that the invention aims to solve]

[0006] By incorporating styrene-based polymers produced by the depolymerization of polystyrene into the manufacture of foam products, the amount of virgin polystyrene required to produce polystyrene foam materials can be reduced, ultimately helping to reduce greenhouse gases, landfill waste, and the need to manufacture styrene-based foam products derived solely from fossil or virgin polystyrene. [Means for solving the problem]

[0007] In some embodiments, the synthetic resin formulation may include a styrene polymer produced by the depolymerization of a polystyrene feedstock manufactured from recycled polystyrene and / or virgin polystyrene. In some embodiments, the recycled polystyrene is polystyrene foam.

[0008] In some embodiments, the styrene-based polymer has a molecular weight similar to that of virgin polystyrene.

[0009] In some embodiments, the styrene-based polymer has a molecular weight of 5,000 amu to 230,000 amu. In some preferred embodiments, the molecular weight is 20,000 amu to 170,000 amu. In even more preferred embodiments, the molecular weight is 35,000 amu to 130,000 amu. In some most preferred embodiments, the molecular weight is 45,000 amu to 95,000 amu.

[0010] In some embodiments, the styrene-based polymer has a melt flow index of 1 g / 10 min to 1000 g / 10 min. In some preferred embodiments, the styrene-based polymer has a melt flow index of 50 g / 10 min to 750 g / 10 min. In some preferred embodiments, the styrene-based polymer has a melt flow index of 75 g / 10 min to 650 g / 10 min. In some preferred embodiments, the styrene-based polymer has a melt flow index of 100 g / 10 min to 550 g / 10 min. In some preferred embodiments, the styrene-based polymer has a melt flow index of 110 g / 10 min to 500 g / 10 min.

[0011] In some embodiments, the styrene-based polymer can reduce the amount of virgin polystyrene required in the synthetic resin formulation. In some embodiments, the styrene-based resin may also include virgin polystyrene. In some embodiments, the styrene-based polymer is at least 20% by mass of the styrene-based resin formulation.

[0012] In some embodiments, the styrene-based polymer has a molecular weight of 10,000 amu or more and 150,000 amu or less, and a melt flow index of 14 g / min or more and 750 g / min or less.

[0013] In some embodiments, the styrene-based polymer can increase the amount of recycled polystyrene that can be used in the styrene-based resin formulation by increasing and homogenizing the melt flow of recycled polystyrene. In some embodiments, the styrene-based polymer is 0.5 to 20% by mass of the styrene-based resin formulation.

[0014] In some embodiments, the styrene-based polymer can reduce the density of the resin formulation for the foam product, thereby reducing the total mass of the product compared to a resin formulation that does not contain the styrene-based polymer.

[0015] In some embodiments, the styrene-based polymer can reduce extruder torque and die pressure, thereby increasing the achievable throughput of the foam product compared to resin formulations that do not contain the styrene-based polymer.

[0016] Various embodiments of the synthetic resin formulations can be used to manufacture bead-formed polystyrene foam products, extruded polystyrene foam products, and / or graphite polystyrene foam products. In certain embodiments, the extruded polystyrene foam product is an insulating or packaging material. In certain embodiments, the bead-formed polystyrene foam product is concrete.

[0017] In some embodiments, the above-mentioned synthetic resin formulation can be used to manufacture rigid polystyrene products, such as containers.

[0018] In some embodiments, the above-mentioned synthetic resin formulation can be used to manufacture injection-molded or extruded ABS parts, such as automotive trim parts. [Brief explanation of the drawing]

[0019] [Figure 1] Figure 1 is a flowchart showing the process of treating polystyrene material to produce styrene-based polymers.

[0020] [Figure 2] Figure 2 is a flowchart showing the process of using styrene-based polymers to manufacture foam formulations.

[0021] [Figure 3] Figure 3 is a graph showing the heat flow of the high molecular weight fraction of polymer A, a styrene-based polymer produced from the depolymerization of waste polystyrene foam.

[0022] [Figure 4]Figure 4 is a graph showing the heat flow of the low molecular weight fraction of Polymer B, a styrene-based polymer produced from the depolymerization of waste polystyrene foam.

[0023] [Figure 5] Figure 5 is a graph showing the heat flow of the low molecular weight fraction of Polymer C, a styrene-based polymer produced from the depolymerization of waste polystyrene foam.

[0024] [Figure 6] Figure 6 is a graph showing the heat flow of the low molecular weight fraction of Polymer D, a styrene-based polymer produced from the depolymerization of waste polystyrene foam.

[0025] [Figure 7A] Figure 7A is a photograph of extruded foam polystyrene containing 99.5% virgin polystyrene / 0.5% talc.

[0026] [Figure 7B] Figure 7B is a photograph of extruded foam polystyrene containing 74.5% virgin polystyrene / 25% recycled polystyrene / 0.5% talc.

[0027] [Figure 7C] Figure 7C is a photograph of extruded foam polystyrene containing 72.5% virgin polystyrene / 25% recycled polystyrene / 0.5% talc and 2% styrene polymer produced by the depolymerization of waste polystyrene.

[0028] [Figure 7D] Figure 7D is a photograph of extruded foam polystyrene containing 70.5% virgin polystyrene / 25% recycled polystyrene / 0.5% talc and 4% styrene polymer produced by the depolymerization of waste polystyrene.

[0029] [Figure 7E]Figure 7E is a photograph of extruded foamed polystyrene containing 68.5% virgin polystyrene, 25% recycled polystyrene, 0.5% talc, and 6% styrene-based polymer produced by the depolymerization of waste polystyrene.

[0030] [Figure 7F] Figure 7F is a photograph of extruded polystyrene foam containing 64.5% virgin polystyrene, 25% recycled polystyrene, 0.5% talc, and 10% styrene-based polymer produced by the depolymerization of waste polystyrene.

[0031] [Figure 8A] Figure 8A is a scanning electron microscope image of extruded polystyrene produced from virgin polystyrene, which contains 0% styrene-based polymers produced from waste polystyrene.

[0032] [Figure 8B] Figure 8B is a scanning electron microscope image of extruded polystyrene produced from virgin polystyrene containing 2% styrene-based polymer produced from waste polystyrene.

[0033] [Figure 8C] Figure 8C is a scanning electron microscope image of extruded polystyrene produced from virgin polystyrene containing 4% styrene-based polymer produced from waste polystyrene.

[0034] [Figure 8D] Figure 8D is a scanning electron microscope image of extruded polystyrene produced from virgin polystyrene containing 6% styrene-based polymer produced from waste polystyrene.

[0035] [Figure 8E] Figure 8E is a scanning electron microscope image of extruded polystyrene produced from virgin polystyrene containing 10% styrene-based polymer produced from waste polystyrene.

[0036] [Figure 9] Figure 9 is a graph showing the effect of styrene-based polymers on the melt flow of virgin and recycled polystyrene feedstock.

[0037] [Figure 10] Figure 10 is a graph showing the effect of styrene-based polymers on the melt flow of various recycled polystyrene feedstocks.

[0038] [Figure 11] Figure 11 is a graph showing the effect of styrene-based polymers on the melt flow of virgin acrylonitrile-butadiene-styrene (ABS) feedstock. [Modes for carrying out the invention]

[0039] The process for converting polystyrene feedstock into styrene-based polymers and its applications were 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 these applications are incorporated herein by reference.

[0040] This disclosure, in particular, teaches a method for producing foam resin formulations using styrene-based polymers.

[0041] In some embodiments of a method for producing foam resin formulations using styrene polymers, polystyrene material is recycled. Converting polystyrene material to styrene 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; subjecting the molten polystyrene material to a chemical depolymerization process in a reactor to produce one or more styrene polymers; cooling the styrene polymers; and / or purifying the styrene polymers.

[0042] In some embodiments, styrene polymers can be modified to add further active sites, such as acrylates, ketones, esters, aldehydes, carboxylic acids, alcohols, and amines. These active sites can serve the purpose of functionalization. In some embodiments, various monomers and / or copolymers, such as acids, alcohols, acetates, acrylates, ketones, esters, aldehydes, amines, and alkenes, such as hexene (but not limited to these), can be grafted onto the depolymerization product to improve compatibility and / or add functionality.

[0043] In some embodiments, various monomers and / or copolymers are grafted via olefin fingerprints and / or aromatic functional groups to improve compatibility and / or add functionality. Grafting can be carried out, in particular, in the reactor, along the cooled flow, and / or in a separate vessel.

[0044] In some embodiments, the polystyrene material can be dissolved in a specific solvent prior to depolymerization to adjust the viscosity of the polymer at various temperatures. In some embodiments, organic solvents such as toluene, xylenes, cymenes, or terpinenes are used to dissolve the polystyrene before it undergoes depolymerization in the reaction bed / container. In certain embodiments, the desired product can be isolated by separation or extraction, and the solvent can be recycled.

[0045] In at least some embodiments, no solvent is required.

[0046] In certain embodiments, the solid polystyrene material is recycled polystyrene. In some embodiments, the recycled polystyrene is pellets produced from recycled polystyrene foam and / or rigid polystyrene. Suitable waste polystyrene materials include, but are not limited to, mixed polystyrene waste, such as bead-formed polystyrene and / or extruded polystyrene, and / or rigid products, such as foam food containers or packaging products. Mixed polystyrene waste can include a variety of melt flows and molecular weights. In some embodiments, the waste polystyrene material feed contains up to 25% of materials other than polystyrene, based on the total mass of the waste polystyrene material feed.

[0047] In some embodiments, virgin polystyrene can also be used as feedstock.

[0048] In some embodiments, the polymer feed material is one of virgin polystyrene, post-industrial waste polystyrene, and post-consumer waste polystyrene; or a combination of virgin polystyrene and one of post-industrial waste polystyrene and post-consumer waste polystyrene; or a combination of virgin polystyrene, post-industrial waste polystyrene, and post-consumer waste polystyrene; or a combination of post-industrial waste polystyrene and post-consumer waste polystyrene.

[0049] In some embodiments, it is desirable to convert the polymer feed material into a lower molecular weight polymer with increased melt flow and olefin content. In some embodiments, this conversion is carried out by heating the polystyrene feed material to produce a molten polystyrene material, and then contacting the molten polystyrene material with a catalyst material in a reaction zone placed at a temperature of 200°C to 400°C, preferably 225°C to 375°C. In some embodiments, a catalyst is not required.

[0050] 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.

[0051] 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 can be housed in a permeable container. In some embodiments, the catalyst may include iron, copper, molybdenum, phosphorus, and / or alumina.

[0052] In some embodiments, the purification of styrene-based polymers utilizes flash separation, an absorbent bed, clay polishing, and / or a film evaporator.

[0053] Figure 1 shows Process 1 for processing polystyrene material. Process 1 can be carried out in batch or as a continuous process. Parameters of Process 1, including but not limited to temperature, flow rate of polystyrene, monomer / copolymer grafted during reaction and / or modification steps, and / or the total number of preheating, reaction, or cooling segments, can be modified to produce styrene polymers of various molecular weights between 5,000 amu and 230,000 amu. In some specific embodiments, such as when the resulting styrene polymer is intended for use in foam formulations, the styrene polymer can have various molecular weights in the range of 40,000 amu and 200,000 amu.

[0054] In some embodiments, during material selection step 10, the polystyrene feed is sorted / selected and / or prepared for processing. In some embodiments, this feed may contain up to 25% polyolefins PP, PE, PET, EVA, EVOH, and lower levels of undesirable additives or polymers, such as nylon, rubber, PVC, ash, fillers, pigments, stabilizers, grit, and / or other unknown particles.

[0055] In some embodiments, the polystyrene feed has an average molecular weight of 150,000 amu or more and 500,000 amu or less. In some embodiments, the polystyrene feed has an average molecular weight of 200,000 amu or more and 300,000 amu or less.

[0056] In some embodiments, the material selected in material selection step 10 includes recycled polystyrene. In other or the same embodiments, the material selected in material selection step 10 includes recycled polystyrene and / or virgin polystyrene.

[0057] In some embodiments, the material selected in the material selection step 10 includes waste polystyrene foam.

[0058] In some embodiments, in solvent addition step 20, a solvent, such as toluene, xylenes, cymenes, or terpinenes, is used to dissolve the polystyrene before it undergoes depolymerization in the reaction bed / container. In certain embodiments, the desired product can be isolated by separation or extraction, and the solvent can be recycled.

[0059] In some embodiments, the material selected in the material selection step 10 can be heated in an extruder in the heating step 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 incoming polystyrene and to control the flow rate of the polystyrene. In some embodiments, the extruder is complemented or completely replaced by a combination of a pump and a heat exchanger.

[0060] In some embodiments, the molten polystyrene material is derived from a polystyrene material feed that is heated to produce the molten polystyrene material. In some embodiments, the polystyrene material feed contains primary virgin polystyrene granules. The virgin granules can have various molecular weights and melt flows.

[0061] In some embodiments, the pre-filtration process 40 may employ both a screen changer and a filter bed, along with other filtration techniques / apparatus, to remove contaminants from the heated material and purify it. In some embodiments, the resulting filtered material is then moved to an optional preheating step 50, which raises the filtered material to a higher temperature before entering the reaction step 60. In some embodiments, the preheating step 50 may use static mixers and / or dynamic mixers, as well as heat exchangers, such as internal fins and heat pipes, among other apparatus and techniques.

[0062] In some embodiments, the material is depolymerized in reaction step 60. This depolymerization can be a purely thermal reaction and / or can use a catalyst. Depending on the starting material and the desired styrene polymer, depolymerization can be used to slightly or drastically reduce the molecular weight of the starting material. In some embodiments, the catalyst used is a zeolite or alumina-supported system, or a combination of the two. In some embodiments, the catalyst is [Fe-Cu-Mo-P] / Al2O3, which is prepared by bonding a ferrous-copper complex to an alumina or zeolite support and reacting it with an acid containing metals and nonmetals to obtain the catalyst material. Other suitable catalyst materials include zeolites, mesoporous silica, H-mordenite, and alumina. The system can also operate in the absence of a catalyst and produce low molecular weight polymers by thermal decomposition.

[0063] In some embodiments, the depolymerization of the polymer material is a catalytic process, a thermal process, utilizes a free radical initiator, and / or utilizes radiation.

[0064] In some embodiments, reaction step 60 can use various technologies / apparatus, particularly fixed-bed reactors, horizontal and / or vertical reactors, and / or static mixers. In some embodiments, reaction step 60 uses multiple reactors and / or reactors divided into multiple sections.

[0065] In some embodiments, after reaction step 60, the depolymerized material enters an optional modification step 70. In at least some embodiments, the modification step 70 includes grafting various monomers and / or copolymers, such as acids, alcohols, acetates and / or alkenes, e.g., hexene (but not limited to these), onto the depolymerization product.

[0066] In some embodiments, the cooling step 80 may use a heat exchanger in conjunction with other techniques / equipment to lower the styrene polymer to a processable temperature before it enters an optional purification step 90. In some embodiments, the styrene polymer is purified / refined before the cooling step 80, for example by a method such as nitrogen stripping.

[0067] Any purification step 90 includes purification and / or decontamination of the styrene polymer. Techniques / apparatus that can be used in purification step 90 include, but are not limited to, flash separation, absorbent bed, clay polishing, distillation, vacuum distillation, and filtration for removing solvents, oils, colorants, ash, inorganics, and coke. In some embodiments, thin-film evaporators or wipe-type film evaporators are used to remove gases, oils and / or greases and / or low molecular weight functionalized polymers from the styrene polymer. In some embodiments, oils, gases, and low molecular weight functionalized polymers can be burned, in turn to aid in carrying out various steps of process 1. In certain embodiments, the desired product can be isolated by separation or extraction, and the solvent can be recycled.

[0068] Process 1 ends in the finished product stage 100, where the initial starting material selected in the material selection stage 10 has become a styrene-based polymer. In at least some embodiments, the styrene-based polymer does not require further processing and / or purification. In other embodiments, the styrene-based polymer produced in the final product stage 100 requires further modification.

[0069] In some embodiments, the resulting depolymerization product material includes monomers (styrene), aromatic solvents, polyaromatic chemical species, oils, and / or low molecular weight functionalized polymers, such as those with increased olefin content.

[0070] In some embodiments, the styrene-based polymer has an average molecular weight of 5,000 amu to 230,000 amu and a melt flow of 1 g / 10 min to 1,000 g / 10 min (as determined by ASTM D1238). In some embodiments, the styrene-based polymer has a glass transition temperature of 30°C to 115°C.

[0071] In some embodiments, the styrene-based polymer has a molecular weight of 5,000 amu to 230,000 amu. In some preferred embodiments, the molecular weight is 20,000 amu to 170,000 amu. In even more preferred embodiments, the molecular weight is 35,000 amu to 130,000 amu. In some most preferred embodiments, the molecular weight is 45,000 amu to 95,000 amu.

[0072] In some embodiments, the styrene-based polymer has a melt flow index of 1 g / 10 min to 1000 g / 10 min. In some preferred embodiments, the styrene-based polymer has a melt flow index of 50 g / 10 min to 750 g / 10 min. In some preferred embodiments, the styrene-based polymer has a melt flow index of 75 g / 10 min to 650 g / 10 min. In some preferred embodiments, the styrene-based polymer has a melt flow index of 100 g / 10 min to 550 g / 10 min. In some preferred embodiments, the styrene-based polymer has a melt flow index of 110 g / 10 min to 500 g / 10 min. In some embodiments, the resulting styrene-based polymer can have a molecular weight range of 40,000 amu to 200,000 amu and a melt flow range of 1 g / 10 min to 750 g / 10 min.

[0073] In some embodiments, the styrene-based polymer has a viscosity of 100 cps to 150,000 cps as measured at 250°C. In some preferred embodiments, the viscosity is 1,000 to 125,000 cps as measured at 250°C. In other preferred embodiments, the viscosity is 5,000 to 100,000 cps as measured at 250°C.

[0074] In some embodiments, the styrene-based polymer has a viscosity of 1,000 cps to 150,000 cps when measured at 225°C. In some preferred embodiments, the viscosity is 1,500 to 120,000 cps when measured at 225°C. In other preferred embodiments, the viscosity is 2,000 to 100,000 cps when measured at 225°C.

[0075] In some embodiments, the resulting styrene-based polymer can have a melt flow range of more than 50 g / 10 min. In some preferred embodiments, the resulting styrene-based polymer can have a melt flow range of 50 g / 10 min to 500 g / 10 min.

[0076] In some embodiments, the resulting styrene-based polymer can be used to manufacture EPS, XPS, and / or graphite polystyrene (GPS) foam. Polystyrene foam can be used in a variety of applications, including but not limited to XPS insulating foam boards, XPS containers, XPS packaging and wrapping materials, EPS packaging and wrapping materials, insulating concrete formwork, interior decorative moldings, ceiling tiles, and other roofing, wall, floor, basement, and structural insulation applications.

[0077] Styrene polymers derived from depolymerized polystyrene can be used to manufacture polystyrene foam products. In some embodiments, this is due to a high molecular weight fraction of the styrene polymer having a more uniform molecular weight distribution and melt flow properties compared to unmodified, i.e., undepolymerized waste polystyrene. In some embodiments, the styrene polymer derived from depolymerized polystyrene has properties comparable to virgin polystyrene, including, but not limited to, molecular weight, molecular weight distribution (polydispersibility), and melt flow index.

[0078] In some embodiments, a styrene-based polymer derived from the depolymerization of waste polystyrene foam can be used in the foam resin formulation at a higher percentage than that of unmodified waste polystyrene foam, while maintaining desired properties of the final foam product, such as density, cell structure, and compressive strength.

[0079] In some embodiments, a fraction of styrene-based polymers derived from the depolymerization of waste polystyrene foam can be used to increase and / or homogenize the melt flow of recycled polystyrene feedstock, thereby increasing the amount of recycled polystyrene that can be used in the foam resin formulation.

[0080] In some embodiments, a fraction of styrene polymer derived from the depolymerization of waste polystyrene foam can be used to reduce the density of the foam product.

[0081] In some embodiments, a fraction of styrene-based polymers derived from the depolymerization of waste polystyrene foam can be used to reduce the extruder torque and die pressure, thereby increasing the throughput of the foam product.

[0082] In some embodiments, the resulting styrene-based polymer can be used to manufacture rigid polystyrene-based products, including but not limited to coat hangers, lids, toys, home appliances, gardening pots, automotive parts, and containers.

[0083] In some embodiments, synthetic resin formulations can be used to manufacture injection-molded or extruded ABS parts such as automotive trim parts.

[0084] Various parameters of Process 1, including but not limited to temperature, pressure, polystyrene flow rate, catalyst selection, monomer / copolymer grafted during reaction and / or modification steps, and the total number of preheating, reaction and / or cooling segments and / or execution time, can be modified to maximize the yield of the styrene-based polymer fraction that can be used in foam resin formulations.

[0085] In some embodiments, EPS and XPS foams can be produced using styrene-based polymers manufactured by the depolymerization of virgin and / or recycled polystyrene. In some preferred embodiments, the styrene-based polymer used to produce the polystyrene foam can be manufactured by the depolymerization of waste polystyrene foam.

[0086] In some embodiments, the parameters of Process 1 can be optimized to improve the compatibility of the styrene polymer with the foam resin formulation and to allow the use of a higher percentage of the styrene polymer in the formulation. For example, by changing various reaction conditions in Process 1, it is possible to produce styrene polymers having an optimal or preferred molecular weight distribution and melt flow characteristics suitable for incorporation into foam resin formulations.

[0087] In some embodiments, styrene-based polymers can be combined with virgin polystyrene and / or waste polystyrene foam to produce foam products.

[0088] In some embodiments, a low molecular weight fraction of a styrene polymer, i.e., a styrene polymer having a molecular weight of 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 available for use in polystyrene synthetic resin formulations, foam formulations, or other extruded polystyrene products by increasing and homogenizing the variable low melt flow of incoming recycled polystyrene. In some embodiments, the low molecular weight fraction of the styrene polymer may be 0.5 to 20% by mass of the formulation used to manufacture polystyrene foam or other extruded polystyrene products.

[0089] Figure 2 shows process 200 for using styrene polymer products produced by a depolymerization process (such as the process described in Figure 1) to manufacture a foam resin formulation. First, the styrene polymer product is selected in the styrene polymer selection step 210, and then added in the compounding step 220 to produce the foam resin. [Examples]

[0090] Exemplary Examples In an exemplary embodiment of the process described in detail, waste polystyrene foam was used to produce a series of depolymerized styrene-based polymers: polymer A, polymer B, polymer C, and polymer D.

[0091] Polymer A was a high molecular weight fraction of styrene-based polymer products with a molecular weight distribution of 175,000 to 225,000 amu. Polymers B and C were low molecular weight styrene-based polymer products with a molecular weight distribution of 50,000 to 75,000. Polymer D had a molecular weight of approximately 65,000.

[0092] Table 1 outlines the melt flow indices and differential scanning calorimetry (DSC) values ​​for polymers A, B, C, and D. [Table 1]

[0093] The heat flow data for polymers A, B, C, and D are plotted in the graphs in Figures 3, 4, 5, and 6, respectively.

[0094] These exemplary depolymerized styrene polymers were then mixed with other components (see Tables 2, 3, 4, and 6) to produce various formulations, which were then tested to determine their various properties. [Table 2] [Table 3]

[0095] Examples of using high-mass styrene polymers to generate foam As shown in Table 4, foam resin formulations prepared from polystyrene feedstock (recycled PS-A) and styrene-based polymers (polymer A) were compared with a control foam resin formulation produced using virgin polystyrene EA3130, a conventional polystyrene starting material used in foam manufacturing.

[0096] Initial tests were conducted on formulations 1-3 (and control I) to determine whether foam could be manufactured using depolymerized polystyrene (at least in a certain percentage).

[0097] To determine whether using depolymerized polystyrene feedstock to form styrene-based polymers affects foam manufacturing, polymer A was compared to recycled PS-A, which is untreated waste polystyrene foam that has not undergone depolymerization process 1. Recycled PS-A had a molecular weight distribution of approximately 225,000–250,000 amu.

[0098] Formulas 1-3 and control I were mixed with a 0.5 pph foaming agent FP-40 and subjected to standard foam extrusion. The extruder conditions for each formula are shown in Table 5.

[0099] The extruder conditions for formulations 1 and 2 were within an appropriate range compared to the control I value, indicating that foam production using styrene polymers does not require a large energy input and does not increase the equipment load during extrusion. These data suggest that foam production using styrene polymers can be carried out under existing production conditions and does not require reconfiguration of production equipment. [Table 4] [Table 5] [Table 6] [Table 7]

[0100] Furthermore, the resin foam formulations were formed into pellets. Whether foam formation was successful for each resin formulation was determined by the ability of each resulting pellet to float in water (Table 6). This indicates that the non-foam form of polystyrene, which has a higher density than water, was properly migrated to the polystyrene foam, which has a lower density than water. [Table 8]

[0101] As shown in Table 6, the resin formed from 100% waste polystyrene foam (composition 3) resulted in sinking pellets. This indicates that a functional foam composition cannot be obtained.

[0102] Resins formed from 100% styrene-based polymer (composition 2) produced sinking pellets (3 out of 4 trials) and floating pellets (1 out of 4 trials). This result indicates that foam materials can be manufactured using 100%, or at least more than 50%, of styrene-based polymers derived from the depolymerization of waste polystyrene.

[0103] A resin formed from 50% virgin polystyrene and 50% polymer A (composition 1) produced floating pellets. This indicates that a functional foam composition was achieved.

[0104] This data also supports the idea that, in at least some embodiments, styrene-based polymers derived from depolymerization allow for lower density in the final foam product, resulting in greater buoyancy.

[0105] Previous attempts to manufacture foam using 50% virgin polystyrene and 50% recycled polystyrene foam were unsuccessful. The fact that formulation 1, a composition of 50% virgin polystyrene and 50% polymer A, can produce a functional foam material indicates that styrene-based polymers derived from the depolymerization of waste polystyrene possess unique properties that are advantageous for use in foam manufacturing, and such properties are not present in unmodified, i.e., undepolymerized waste polystyrene foam.

[0106] Examples of using low-mass styrene polymers to generate foam Foam testing has also been completed in which polymers B and C, low molecular weight styrene-based polymers derived from the depolymerization of waste polystyrene, were used as additives at low concentrations in the overall formulation.

[0107] As shown in Table 4, foam resin formulations prepared from recycled PS-B and styrene-based polymers (polymer B and polymer C) were compared with a control foam resin formulation produced using virgin polystyrene 535B, a conventional polystyrene starting material used in foam manufacturing.

[0108] Formulas 4-57 were mixed with the blowing agent HCFO-1233zd(E) and subjected to standard foam extrusion. Formulas 4-57 used 0.5% talc as a nucleating agent (via a 20% masterbatch). All of formulas 4-57 yielded favorable foam products.

[0109] Table 5 shows the extruder conditions and main characteristics (foam density and feed rate) for each compound.

[0110] Extruder conditions for formulations containing polymer B or polymer C resulted in a decrease in die pressure extruder torque. These values ​​were within an appropriate range compared to those for the control formulation, indicating that foam production using styrene-based polymers requires less energy input and reduces the equipment load during extrusion.

[0111] The reduction in extruder torque and die pressure indicates that polymers derived from the depolymerization of waste polystyrene enable increased throughput in XPS foam production.

[0112] These data demonstrate that foam manufacturing using styrene-based polymers is feasible under existing manufacturing conditions and does not require the reorganization of manufacturing equipment.

[0113] Figure 7A is a photograph showing foam manufactured from virgin polystyrene (formulation 4) containing 0% styrene-based polymers derived from waste polystyrene.

[0114] Figure 7B is a photograph showing foam produced from virgin polystyrene and recycled polystyrene (composition 10) with 0% styrene-based polymer derived from waste polystyrene.

[0115] Figure 7C is a photograph showing foam produced from virgin polystyrene and recycled polystyrene (compound 11) in the presence of 2% styrene-based polymer derived from waste polystyrene.

[0116] Figure 7D is a photograph showing foam produced from virgin polystyrene and recycled polystyrene (compound 12) with the presence of 4% styrene-based polymer derived from waste polystyrene.

[0117] Figure 7E is a photograph showing foam produced from virgin polystyrene and waste polystyrene (compound 13) in the presence of 6% styrene-based polymer derived from waste polystyrene.

[0118] Figure 7F is a photograph showing foam produced from virgin polystyrene and waste polystyrene (compound 14) in the presence of 10% styrene-based polymer generated from waste polystyrene.

[0119] As can be seen from Table 7, the density of the manufactured foams containing polymer B or polymer C was generally lower compared to the controls.

[0120] Samples of the resin foam formulation were taken, and scanning electron microscope images were taken to measure the foam's integrity and open cell content. The foam's integrity and open cell content were not adversely affected by the inclusion of styrene-based polymers derived from the depolymerization of waste polystyrene.

[0121] Figure 8A is a scanning electron microscope image showing a foam (formulation 4) manufactured from virgin polystyrene with 0% styrene-based polymer derived from waste polystyrene.

[0122] Figure 8B is a scanning electron microscope image showing a foam produced from virgin polystyrene (composition 5) in the presence of 2% styrene-based polymer generated from waste polystyrene.

[0123] Figure 8C is a scanning electron microscope image showing a foam produced from virgin polystyrene (composition 6) in the presence of 4% styrene-based polymer generated from waste polystyrene.

[0124] Figure 8D is a scanning electron microscope image showing a foam produced from virgin polystyrene (composition 7) in the presence of 6% styrene-based polymer generated from waste polystyrene.

[0125] Figure 8E is a scanning electron microscope image showing a foam produced from virgin polystyrene (composition 8) in the presence of 10% styrene-based polymer generated from waste polystyrene.

[0126] This data demonstrates that styrene-based polymers derived from the depolymerization of waste polystyrene possess unique properties that make them advantageous for use in foam manufacturing. These properties include density modifiers and throughput modifiers.

[0127] Examples of styrene-based polymers as melt flow modifiers To determine whether low molecular weight fractions of styrene-based polymers can be used to increase the melt flow of virgin or recycled polystyrene feedstock, polymer C or polymer D, which are styrene-based polymers with a molecular weight of approximately 65,000 amu, were added to virgin or recycled polystyrene feedstock, as shown in Table 7. The melt flow of each styrene-based polymer-polystyrene resin blend was then tested and compared to untreated virgin or recycled polystyrene (PS) feedstock. The resulting melt flow indices for each blend are also shown in Table 7. [Table 9]

[0128] Control II serves as a control for formulations 58-62, Control III serves as a control for formulations 63-67, Control IV serves as a control for formulations 68-72, Control V serves as a control for formulations 73-75, and Control VI serves as a control for formulations 76-80.

[0129] As shown in Table 7, the obtained melt flow index increased as the percentage of styrene-based polymers increased for both virgin and recycled polystyrene feedstocks.

[0130] Figure 9 is a graph showing the percentage change in melt flow index for resin blend control II, control III, and formulations 58-67.

[0131] Figure 10 is a graph showing the percentage change in melt flow index for resin blend control IV, control V, and formulations 68-75.

[0132] Figure 11 is a graph showing the percentage change in melt flow index for resin blend control VI and formulations 76-80.

[0133] These data demonstrate that low molecular weight fractions of styrene-based polymers can be used to increase the melt flow of both virgin and recycled polystyrene and ABS. Increasing the melt flow of recycled polystyrene can impart the ability to be used in applications such as synthetic resin formulations, foam resin formulations, and formulations for obtaining rigid polystyrene and ABS products.

[0134] These data, taken together, indicate that styrene-based polymers derived from the depolymerization of waste polystyrene possess unique properties that make them advantageous for use in synthetic resin formulations. These unique properties are imparted during the depolymerization process and include, at a minimum, a narrower distribution of molecular weight and melt flow compared to unmodified recycled / waste polystyrene.

[0135] While certain elements, embodiments, and uses of the present invention have been shown and described, it will be understood that the present invention is not limited thereto, as modifications can be made without departing from the scope of this disclosure, particularly in light of the teachings set forth above. Furthermore, all of the claims are incorporated by reference to the description of preferred embodiments. This disclosure also discloses embodiments as illustrated below. [Embodiment 1] A synthetic resin compound containing a styrene-based polymer produced by the depolymerization of polystyrene feedstock. [Embodiment 2] The synthetic resin compound according to Embodiment 1, wherein the styrene-based polymer has a molecular weight of 5,000 amu or more and 150,000 amu or less. [Embodiment 3] The synthetic resin compound according to Embodiment 2, wherein the styrene-based polymer has a melt flow index of 25 g / min or more and 1,000 g / min or less. [Embodiment 4] The synthetic resin compound according to Embodiment 2, wherein the styrene-based polymer increases and homogenizes the melt flow of recycled polystyrene, thereby increasing the amount of recycled polystyrene that can be used in the synthetic resin compound. [Embodiment 5] The synthetic resin compound according to Embodiment 2, wherein the styrene-based polymer increases the melt flow of PS and / or ABS plastics. [Embodiment 6] The synthetic resin compound according to Embodiment 2, wherein the styrene-based polymer increases the throughput for extruding PS and / or ABS plastics. [Embodiment 7] The synthetic resin compound according to Embodiment 2, wherein the styrene-based polymer is present in an amount of 0.5 to 20% by mass of the synthetic resin compound. [Embodiment 8] The synthetic resin compound according to Embodiment 2, wherein the styrene-based polymer makes up at least 20% by mass of the synthetic resin compound. [Embodiment 9] The synthetic resin compound of Embodiment 1, which is used to manufacture an extruded polystyrene foam product. [Embodiment 10] The synthetic resin compound according to Embodiment 9, wherein the extruded polystyrene foam product is an insulating material. [Embodiment 11] The synthetic resin compound according to Embodiment 9, wherein the extruded polystyrene product is a packaging material. [Embodiment 12] The synthetic resin compound according to Embodiment 1, wherein the synthetic resin compound is used to manufacture a bead-type expanded polystyrene foam product. [Embodiment 13] The synthetic resin compound according to Embodiment 12, wherein the aforementioned bead-type expanded polystyrene foam product is concrete. [Embodiment 14] The synthetic resin compound according to Embodiment 1, wherein the synthetic resin compound is used to manufacture a graphite polystyrene foam product. [Embodiment 15] The synthetic resin compound according to Embodiment 1, wherein the polystyrene feedstock contains virgin polystyrene. [Embodiment 16] The synthetic resin compound according to Embodiment 1, wherein the polystyrene feedstock includes recycled polystyrene. [Embodiment 17] The synthetic resin compound according to Embodiment 16, wherein the recycled polystyrene is polystyrene foam. [Embodiment 18] The synthetic resin compound according to Embodiment 1, wherein the styrene-based polymer has a molecular weight similar to that of virgin polystyrene. [Embodiment 19] The synthetic resin compound according to Embodiment 1, wherein the styrene-based polymer has a molecular weight of 150,000 amu or more and 230,000 amu or less. [Embodiment 20] The synthetic resin compound according to Embodiment 19, wherein the styrene-based polymer has a melt flow index of 1 g / 10 min to 25 g / 10 min. [Embodiment 21] The synthetic resin compound according to Embodiment 1, wherein the styrene-based polymer reduces the amount of virgin polystyrene required for the synthetic resin compound. [Embodiment 22] The synthetic resin compound according to Embodiment 1, wherein the synthetic resin compound is used to manufacture injection-molded or extruded ABS products. [Embodiment 23] The synthetic resin compound according to Embodiment 1, wherein the synthetic resin compound is used to manufacture a rigid polystyrene product. [Embodiment 24] The synthetic resin compound according to Embodiment 23, wherein the rigid polystyrene product is a container.

Claims

1. A polystyrene foam product comprising a synthetic resin compound containing a depolymerized polystyrene feedstock, wherein the depolymerized polystyrene feedstock is produced by subjecting the polystyrene feedstock to a catalytic depolymerization process, and the depolymerized polystyrene feedstock has a melt flow index (determined by ASTM D1238) of 50 g / 10 min or more and 1,000 g / 10 min or less.

2. A polystyrene foam product comprising a synthetic resin compound containing a depolymerized polystyrene feedstock, wherein the depolymerized polystyrene feedstock has a melt flow index (determined by ASTM D1238) of 50 g / 10 min to 1,000 g / 10 min, and the polystyrene foam product is an injection-molded or extruded ABS product.

3. The polystyrene foam product according to claim 1 or 2, wherein the depolymerized polystyrene feedstock has a molecular weight of 5,000 amu or more and 150,000 amu or less.

4. The polystyrene foam product according to claim 2 or 3, wherein the depolymerized polystyrene feedstock has a melt flow index (determined by ASTM D1238) of 50 g / 10 min or more and 750 g / 10 min or less.

5. The polystyrene foam product according to claim 2 or 3, wherein the depolymerized polystyrene feedstock increases the amount of recycled polystyrene that can be used in the synthetic resin compound by increasing the melt flow of recycled polystyrene.

6. The polystyrene foam product according to claim 2 or 3, wherein the depolymerized polystyrene feedstock increases the melt flow of PS and / or ABS plastic.

7. The polystyrene foam product according to claim 2 or 3, wherein the depolymerized polystyrene feedstock increases the throughput for extruding PS and / or ABS plastics.

8. The polystyrene foam product according to claim 2 or 3, wherein the depolymerized polystyrene feedstock is 0.5 to 20% by mass of the synthetic resin compound.

9. The polystyrene foam product according to claim 2 or 3, wherein the depolymerized polystyrene feedstock is at least 20% by mass of the synthetic resin compound.

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

11. The polystyrene foam product according to claim 10, wherein the extruded polystyrene foam product is an insulating material.

12. The polystyrene foam product according to claim 10, wherein the extruded polystyrene foam product is a packaging material.

13. The polystyrene foam product according to claim 1, wherein the polystyrene foam product is a polystyrene foam product produced by the bead method.

14. The polystyrene foam product according to claim 13, wherein the bead-type expanded polystyrene foam product is a concrete formwork.

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

16. The polystyrene foam product according to claim 1 or 2, wherein the polystyrene feedstock includes virgin polystyrene.

17. The polystyrene foam product according to claim 1 or 2, wherein the polystyrene feedstock includes recycled polystyrene.

18. The polystyrene foam product according to claim 17, wherein the recycled polystyrene is polystyrene foam.

19. The polystyrene foam product according to claim 1, wherein the depolymerized polystyrene feedstock has a molecular weight similar to that of virgin polystyrene.

20. The polystyrene foam product according to claim 1 or 2, wherein the depolymerized polystyrene feedstock has a molecular weight of 150,000 amu or more and 230,000 amu or less.

21. The polystyrene foam product according to claim 1 or 2, wherein the depolymerized polystyrene feedstock reduces the amount of virgin polystyrene required for the polystyrene foam product.

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

23. The polystyrene foam product according to claim 22, wherein the rigid polystyrene product is a container.

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