Uses of Styrenic Polymers Derived Through Depolymerized Polystyrene

Abstract

A latex and solution with UV-active monomers created using styrenic polymers created via the depolymerization of a polystyrene feedstock. In some embodiments the polystyrene feedstock contains recycle polystyrene. In some embodiments, the styrenic polymers contain olefins. In some embodiments, the latex and solution with UV-active monomers are used in ink formulations. In some embodiments, latex and solution UV-active monomers can replace styrenated acrylics within flexo and/or gravure ink formulations. Other applications of the latex and solution with UV-active monomers can include, but are not limited to, coatings, paints, adhesives. Additional applications of the latex can include but are not limited to immunoassays.

Claims

1. A latex comprising: (a) a styrenic polymer created via depolymerization of a polystyrene feedstock.

2. The latex of claim 1 wherein said polystyrene feedstock comprises recycled polystyrene.

3. The latex of claim 1 wherein the particle size of said latex is greater than 1 nm.

4. The latex of claim 1 wherein the particle size of said latex is between and inclusive of 150-220 nanometers.

5. The latex of claim 1 wherein said styrenic polymer comprises an at least one olefin.

6. The latex of claim 5 wherein said at least one olefin is less than 1% of the total weight of said styrenic polymer.

7. The latex of claim 1 wherein said styrenic polymer has a molecular weight between 20000-200000 amu.

8. The latex of claim 1 wherein said styrenic polymer has a melt flow index between and inclusive of 10 g/10 min to 200 g/10 min.

9. The latex of claim 1, wherein said latex is part of a coating.

10. An ink comprising: (a) a pigment; and (b) an additive.

11. The ink of claim 10 further comprising: (c) a styrenic polymer created via depolymerization of a polystyrene feedstock; (d) a UV-Active monomer; (e) a photoinitiator; and (f) a solvent.

12. The ink of claim 10 further comprising: (c) a latex comprising a styrenic polymer created via depolymerization of a polystyrene feedstock; (d) a UV-Active monomer; and (e) a photoinitiator.

13. The ink of claim 12 wherein said pigment is an organic pigment.

14. The ink of claim 12 wherein said pigment is a mineral pigment.

15. The ink of claim 12 wherein said polystyrene feedstock comprises recycled polystyrene.

16. The ink of claim 15 wherein the particle size of said latex is between and inclusive of 150-220 nanometers.

17. The ink of claim 15 wherein said styrenic polymer comprises an at least one olefin.

18. The ink of claim 17 wherein said at least one olefin is less than 1% of the total weight of said styrenic polymer.

19. An adhesive comprising: (a) a latex comprising a styrenic polymer created via depolymerization of a recycled polystyrene feedstock.

20. The adhesive of claim 19 wherein said styrenic polymer comprises an at least one olefin, wherein said at least one olefin is less than 1% of the total weight of said styrenic polymer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIG. 1 is a flowchart illustrating a process for treating polystyrene material to create styrenic polymers.

[0020] FIG. 2 is a schematic of a phase inversion emulsification procedure.

[0021] FIG. 3 is a schematic of the process by which a styrenic polymer/UV-active monomer blend is produced.

[0022] FIG. 4 is a flowchart illustrating a process for using styrenic polymers to create inks.

[0023] FIG. 5 is a flowchart illustrating a process for using styrenic polymers to create oligomer/monomer formulations.

[0024] FIG. 6 is an overlay of a series of Differential Scanning Calorimetry (DSC) thermograms of various styrenic polymers produced via depolymerization of polystyrene.

[0025] FIG. 7 is a Nuclear Magnetic Resonance (NMR) spectra of styrenic polymers produced via depolymerization.

[0026] FIG. 8 is an enlarged version of section A of FIG. 7 showing the peaks corresponding to the presence of olefins.

[0027] FIG. 9 is a graph showing the rheology of various inks, including those made with styrenic polymers created via the depolymerization of polystyrene.

[0028] FIG. 10 is a photograph of a styrenic polymer latex.

[0029] FIG. 11 is a photograph of a styrenic polymer/UV-active monomer blend.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENT(S)

[0030] Styrenic polymers derived from depolymerized polystyrene can be used where traditional higher molecular weight polystyrene plastic can not be used without modification. Such applications include, but are not limited to, inks, paints, coatings, adhesive formulations, and/or immunoassay tests.

[0031] Styrenic polymers derived from depolymerized polystyrene can also be used as replacement to traditionally used materials that originated from crude oil sources. One use for styrenic polymers created via depolymerization of polystyrene is to replace styrenated acrylics in aqueous inks such as flexo and gravure ink formulations. Traditionally styrenated acrylics are used in connection with solvents, pigments and additives in aqueous ink formulations. One problem with using polystyrene plastic in aqueous ink is they are insoluble due to the high molecular weight and lack of polarity. This challenge is overcome through the controlled depolymerization of polystyrene plastics to create styrenic polymers with lower molecular weights and greater polarity. The ability to tune the properties of the styrenic polymers derived from depolymerized polystyrene plastic allows styrenic polymer products to be designed specifically for use with latex formulations. Use of styrenic polymers derived from waste polystyrene plastic can help reduce greenhouse gases, landfill waste, and the need for the production of new styrenic products derived from fossil or virgin polystyrene.

[0032] A method for producing latex formulations using styrenic polymers is disclosed. These latexes can be used in various applications including inks.

[0033] In some embodiments, the polystyrene material is first be converted into the styrenic polymers. A process for achieving this is discussed in International Application PCT/CA2017/051166 which is hereby incorporated by reference. In some embodiments, the polystyrene material is recycled. Converting the polystyrene material into the styrenic polymers can include selecting a solid polystyrene material; heating the solid polystyrene material in an extruder to create a molten polystyrene material; filtering the molten polystyrene material; placing the molten polystyrene material through a chemical depolymerization process in a reactor to create styrenic polymer(s); cooling the styrenic polymer; and/or purifying the styrenic polymer(s).

[0034] In at least some embodiments, the materials do not need to be purified. In at least several embodiments, additives/residues do not disrupt the latex formulation. In at least some embodiments, the styrenic polymer(s) can be dispersed in water to create various latexes and/or emulsions. In at least some embodiments, this is accomplished via traditional emulsification techniques such as phase inversion emulsification in which the styrenic polymer is dissolved into a complementary solvent and transferred into an aqueous dispersion (latex) after which the original compatible solvent is stripped.

[0035] FIG. 2 illustrates an embodiment of phase inversion emulsification. In step 202 and 204 water is gradually added into a hydrophobic polymer dissolved in an organic solvent. In step 206 a saturated inversion occurs (the water droplet in the oil become oil droplets in water). In step 208 the organic solvent is removed by distillation resulting in a stable late emulsion.

[0036] Other processes can be used to form the latexes including, but not limited to, attrition of polymer(s) in water with at least one surfactant; homogenization of polymer(s) in at least one solvent with water and at least one emulsifier; mixing molten polymer(s) with at least one emulsifier and hot water under high pressure, high temperatures, and/or high shear force; and techniques utilizing ultrasound.

[0037] Latexes formed via the methods above can be used in various products including, but not limited to ink formulations. In some embodiments, these styrenic polymer latexes can replace styrenated acrylics within flexo and/or gravure ink formulations. Other applications of styrenic polymer latexes include, but are not limited to, coatings, paints, adhesives and immunoassays.

[0038] In at least some embodiments, the styrenic polymer(s) are soluble in organic mediums and/or aqueous formulations.

[0039] Another use for styrenic polymers created via depolymerization polystyrene is to replace traditional oligomeric components in solvent based ink formulations. Traditionally oligomers are used in connection with monomers, pigments, photoinitiators and additives in aqueous ink formulations.

[0040] In at least some embodiments, the styrenic polymers created via depolymerization polystyrene do not need to be purified. In at least several embodiments, additives/residues do not disrupt the solubilization process.

[0041] Other applications of styrenic polymer/UV-active monomer formulations include but are not limited to, coatings, paints, adhesives.

[0042] FIG. 3 illustrates an embodiment of styrenic polymer solubilisation in UV-active monomer. In step 302 styrenic polymer is gradually added into a UV-active monomer at a desired temperature. The mixture is then vigorously stirred to induce solubilization at step 304.

[0043] In some embodiments, the styrenic polymer(s) contain active sites (such as olefin moieties). These active sites are often a signature of materials produced via a depolymerization process. In some embodiments, the depolymerization process incorporates additional olefin content into the backbone of the polymer. Backbone or terminal olefins are identifiable features that are not present in styrenic polymer derived through polymerization methods. FIG. 7 and FIG. 8 show Nuclear Magnetic Resonance (NMR) Spectra of styrenic polymer material, supporting the presence of olefin species. Backbone or terminal olefins, which involve double bonded carbon atoms, are more polar in nature compared to polymers with saturated backbones. This makes polymers with olefin content more compatible in aqueous latex formations than traditional polystyrene. The olefin content also lends itself to improved solubilisation in various UV-active monomers.

[0044] In some embodiments the styrenic polymers can be further modified to add additional active sites such as carboxylic acids, maleic acid, maleic anhydride, and amines. The active sites can serve functionalization purposes. In some embodiments, to improve compatibility and/or add function, various monomers and/or copolymers such as, but not limited to, acids, alcohols, acetates, amines, and alkenes such as hexene can be grafted onto the depolymerized product.

[0045] In some embodiments, to improve compatibility and/or add function, the various monomers and/or copolymers are grafted on via the olefin fingerprint. Grafting can take place, among other places, in a reactor, in line with the stream after cooling, and/or in a separate vessel.

[0046] In some embodiments, to improve compatibility and/or add function, the various monomers and/or copolymers are grafted on via the aromatic functionality. Grafting can take place, among other places, in a reactor, in line with the stream after cooling, and/or in a separate vessel.

[0047] In some embodiments, the polystyrene material can be dissolved in certain solvents 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 within the reactor bed/vessel. In certain embodiments, the desired product can be isolated via separation or extraction and the solvent can be recycled.

[0048] In at least some embodiments, solvents are not required.

[0049] In certain embodiments, the solid polystyrene material is a recycled polystyrene. In some embodiments, the recycled polystyrene is a pellet made from recycled polystyrene foam and/or rigid polystyrene. Suitable waste polystyrene material includes, but it not limited to, mixed polystyrene waste such as expanded, and/or extruded polystyrene foam, and/or rigid products. For example, foam food containers, or packaging products. The mixed polystyrene waste can include various melt flows and molecular weights. In some embodiments, the waste polystyrene material feed includes up to 25% of material that is other than polystyrene material, based on the total weight of the waste polystyrene material feed. In some embodiments, virgin polystyrene can also be used.

[0050] In some embodiments, the polymeric feed material is one of, or a combination of, virgin polystyrene and/or any one of, or combinations of post-industrial and/or post-consumer waste polystyrene.

[0051] In some embodiments, it is desirable to convert the polymeric feed material into lower molecular weight polymers, with increased melt flow and olefin content. In some embodiments, the conversion is affected by heating the polystyrene feed material to generate molten polystyrene material, and then contacting the molten polystyrene material with a catalyst material within a reaction zone disposed at a temperature between 200 degrees Celsius and 400 degrees Celsius, preferable between 275-375 degrees Celsius. In some embodiments, a catalyst is not required.

[0052] The molecular weight, polydispersity, glass transition, melt flow, and olefin content that is generated via the depolymerization depends on the residence time of the polystyrene material within the reaction zone.

[0053] In some embodiments the depolymerization process utilizes a catalyst such as [FeCuMoP]/Al.sub.2O.sub.3, Zeolite or alumina supported systems, and/or thermal depolymerization. In some embodiments, the catalyst can be contained in a permeable container. In some embodiments, the depolymerization can occur through the action of free radical initiators and/or exposure to radiation.

[0054] In some embodiments, the purification of styrenic polymers utilizes flash separation, distillation, vacuum stripping, absorbent beds, clay polishing and/or film evaporators.

[0055] FIG. 1 illustrates Process 1 for treating polystyrene material. Process 1 can be run in batches or a continuous process. The parameters of Process 1, including but not limited to temperature, flow rate of polystyrene, monomers/copolymers grafted during the reaction and/or modification stages, and total number of pre-heat, reaction, or cooling segments, can be modified to create styrenic polymers of varying molecular weights between and inclusive of 20,000-200,000 amu. In some more preferred embodiments, the styrenic polymers have varying molecular weights between and inclusive of 50,000-150,000 amu. In some even more preferred embodiments, the styrenic polymers have varying molecular weights between and inclusive of 55,000-120,000 amu.

[0056] In Material Selection Stage 10, polystyrene feed is sorted/selected and/or prepared for treatment. In some embodiments, the feed can contain up to 25% polyolefins, PET, EVA, EVOH, and lower levels of undesirable additives or polymers, such as nylon, rubber, PVC, ash, filler, pigments, stabilizers, grit or other unknown particles.

[0057] In some embodiments, the polystyrene feed has an average molecular weight between and inclusive of 150000 amu and 500000 amu. In some of these embodiments, the polystyrene feed has an average molecular weight between and inclusive of 200000 amu and 250000 amu.

[0058] In some embodiments, the material selected in Material Selection Stage 10 comprises recycled polystyrene. In other or the same embodiments, the material selected in Material Selection Stage 10 comprises recycled polystyrene and/or virgin polystyrene.

[0059] In Solvent Addition Stage 20, solvents, such as toluene, xylenes, cymenes, or terpinenes, are used to dissolve the polystyrene before it undergoes depolymerization within the reactor bed/vessels. In certain embodiments, the desired product can be isolated via separation or extraction and the solvent can be recycled.

[0060] In some embodiments, the material selected in Material Selection Stage 10 is can be heated in Heat Stage 30 an extruder and undergoes Pre-Filtration Process 40. In some embodiments, the extruder is used to increase the temperature and/or pressure of the incoming polystyrene and is used to control the flow rates of the polystyrene. In some embodiments, the extruder is complimented by or replaced entirely by pump/heater exchanger combination.

[0061] In some embodiments, the molten polystyrene material is derived from a polystyrene material feed that is heated to effected generation of the molten polystyrene material. In some embodiments, the polystyrene material feed includes primary virgin granules of polystyrene. The virgin granules can include various molecular weights and melt flows.

[0062] Pre-Filtration Process 40 can employ both screen changers and filter beds, along with other filtering techniques/devices to remove contaminants from and purify the heated material. The resulting filtered material is then moved into an optional Pre-Heat Stage 50 which brings the filtered material to a higher temperature before it enters Reaction Stage 60. Pre-Heat Stage 50 can employ, among other devices and techniques, static and/or dynamic mixers and heat exchangers such as internal fins and heat pipes.

[0063] Material in Reaction Stage 60 undergoes depolymerization. This depolymerization can be a purely thermal reaction and/or it can employ catalysts. Depending on the starting material and the desired styrenic polymer latex, depolymerization might be used for a slight or extreme reduction of 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 [FeCuMoP]/Al.sub.2O.sub.3 prepared by binding a ferrous-copper complex to an alumina or zeolite support and reacting it with an acid comprising metals and non-metals to obtain the catalyst material. In some embodiments, the catalyst comprises Al, Fe, Cu, and O, prepared by binding ferrous and copper complexes to an alumina and/or zeolite support. Other suitable catalyst materials include, but are not limited to, zeolite, mesoporous silica, H-mordenite and alumina. The system can also be run in the absence of a catalyst and produces lower molecular weight polymer through thermal degradation.

[0064] Reaction Stage 60 can employ a variety of techniques/devices including, among other things, fixed beds, 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.

[0065] After Reaction Stage 60 the depolymerized material enters optional Modification Stage 70. Modification Stage 70 involves grafting various monomers and/or copolymers such as, but not limited to, acids, alcohols, acetates, and alkenes such as hexene onto the depolymerized product.

[0066] Cooling Stage 80 can employ heat exchangers, along with other techniques/devices to bring the styrenic polymer latex down to a workable temperature before it enters optional Purification Stage 80. In some embodiments, cleaning/purification of the styrenic polymers via such methods such as nitrogen stripping occurs before Cooling Stage 80.

[0067] Optional Purification Stage 90 involves the refinement and/or decontamination of the styrenic polymers. Techniques/devices that can be used in Purification Stage 90 include, but are not limited to, flash separation, absorbent beds, clay polishing, distillation, vacuum distillation and filtration to remove solvents, oils, color bodies, ash, inorganics, and coke. In some embodiments, a thin or wiped film evaporator is used to remove gas, oil, and/or grease and/or lower molecular weight functionalized polymers from the styrenic polymer latex. In some embodiments, the oil, gas, and lower molecular weight functionalized polymers can in turn be burned to help run various Stages of Process 1. In certain embodiments, the desired product can be isolated via separation or extraction and the solvent can be recycled.

[0068] Process 1 ends at Finished Product Stage 100 in which the initial starting material selected in Material Selection Stage 10 has been turned into a styrenic polymers. In at least some embodiments, the styrenic polymers do not need additional processing and/or refining. In other embodiments, the styrenic polymers created at Finished Product Stage, need additional modifications.

[0069] In some embodiments, the styrenic polymers has an average molecular weight between and inclusive of 20000 amu and 200000 amu, a melt flow between and inclusive of 0 g per 10 minutes and 100 g/10 min (determined via ASTM D1238). In some embodiments, the styrenic polymer has a glass transition temperature between and inclusive of 30-115 C.

[0070] In some of embodiments, the styrenic polymer has an average molecular weight between and inclusive of 40000-100000, a melt flow index between and inclusive of 10 g/10 min to 200 g/10 min (determined via ASTM D1238).

[0071] In some embodiments, the styrenic polymer comprises between 0.1% and 5% olefin content on the backbone of the chain.

[0072] In some embodiments, the styrenic polymer comprises greater than 50 ppm of zinc; greater than 20 ppm titanium; and/or greater than 20 ppm iron. In at least some embodiments, the presence of these metals confirms that the styrenic polymer was derived through either post-consumer or post-industrial waste polystyrene plastic. In some embodiments, these metals are well dispersed in the styrenic polymer adding both polarity and reactivity. This dispersion can make the styrenic polymer more compatible in various organic and aqueous solvent formations than traditional polystyrene. In addition, the added metal content can allow the styrenic polymer to act as a coupling agent with other multi-polymer systems.

[0073] In some embodiments the resulting latex has a particle size greater than 1 nanometer. In some embodiments the resulting latex has a particle size greater than 1 micrometer. In some embodiments, the resulting latex has particle size distributions between and inclusive of 50-300 nanometers. In some preferred embodiments, the resulting latex has particle size distributions between and inclusive of 100-250 nanometers. In some more preferred embodiments, the resulting latex has particle size distributions between and inclusive of 150-200 nanometers.

[0074] In some embodiments, the generated depolymerization product material includes monomer (styrene), aromatic solvents, polyaromatic species, oils, and/or lower molecular weight functionalized polymers, such as those with increased olefin content.

Example of Styrenic Polymers Latex Ink Formulations

[0075] FIG. 4 shows Process 400 for using a styrenic polymer product created via a depolymerization process (such as the one described in FIG. 1) to create a finished product, such as, but not limited to, an ink. First a styrenic polymer product is chosen in Styrenic Polymer Selection 410. The styrenic polymer is then emulsified in Emulsification Stage 420 to create a latex. The resulting latex is then added in Formulation Stage 430 to create a finished product (such as an ink).

[0076] In an illustrative embodiment of the present process, three styrenic polymers formed via depolymerization of polystyrene were identified for possible latex formulations. (See Table 1). Polymer A (which had a low molecular weight); Polymer B (which had a mid-range molecular weight); and Polymer C (which had a high molecular weight). As a result of the varying molecular weight of the three polymers, the glass transition temperatures also varied. FIG. 6 shows an overlay of differential scanning calorimetry thermograms of polymers A-C showing variances in the glass transition temperatures.

TABLE-US-00001 TABLE 1 Styrenic Polymers Polymer A Polymer B Polymer C Mw 56167 88901 104915 (Weight-average molecular weight as determined by gel permeation chromatography) MFI >50 29.67 9.66 (Melt Flow Index as determined by ASTM D1238) Glass Transition Temperature.sub.initial 63.81 73.19 88.71 (As determined by differential scanning calorimetry) Glass Transition Temperature.sub.mid 80.91 85.18 95.34 (As determined by differential scanning calorimetry) Glass Transition Temperature.sub.end 97.78 97.17 101.79 (As determined by differential scanning calorimetry) Solid Loading Range 24.7 28.4 27.9

[0077] Each of the polymer samples was successfully formed into a latex via phase inversion emulsification. In some of these embodiments the latexes are stable for over a year at room temperature with solid loading ranges between 10% and 70%. In some preferred embodiments the latexes are stable for over a year at room temperature with solid loading ranges between 20 and 60%. In some more preferred embodiments, the latexes are stable for over two years at room temperature with solid loading ranges between 25 and 45%.

[0078] FIG. 10 is a photograph of a styrenic polymer latex. The sample in the image is over 24 months old with no phasing/separation/destabilisation occurring.

[0079] These latex formulations were then used to create various ink formulations (Polymer A Ink, Polymer B Ink, and Polymer C Ink) as show in Table 2.

TABLE-US-00002 TABLE 2 Ink Components as Percentage of Total Weight Polymer Polymer Polymer Control A Ink B Ink C Ink Ink Acrylic Polymer 10.0 10.0 10.0 10.0 Solution (30%) Polymer A 45.5 0 0 0 (24.7%) Polymer B 0 41.0 0 0 (28.4%) Polymer C 0 0 41.9 0 (27.9%) Acrylic 0 0 0 30 Dispersion (30%) Water 0 4.5 3.6 15.5 Hydrophilic 1.0 1.0 1.0 1.0 solvent PE Wax 3.0 3.0 3.0 3.0 Surfactant 0.5 0.5 0.5 0.5 Cyan Pigment 40.0 40.0 40.0 40.0 Dispersion

[0080] Polymer A, B and C Inks along with Control Ink underwent several tests. The styrenic inks, performed at least as good (rub resistance, coefficient of friction), if not better (blocking, reduced ink transfer during rub testing, overall image robustness) than the Control Ink in all the tests. This indicates that styrenic polymers formed via the depolymerization of waste polystyrene can act as substitutes for styrenated acrylics (derived from fossil fuel sources) in aqueous ink formulations. The improved efficacy of the ink formulation is likely due to the hydrophobic nature of the polymer and the molecular weight of the styrenic polymers used. The highest molecular weight polymer, Polymer C, afforded significantly reduced ink transfer during rub testing and improved the image robustness of the ink. There were gradual improvements as the molecular weight of the polymer increased (i.e. from Polymer A to Polymer C).

TABLE-US-00003 TABLE 3 Ink Tests Polymer Polymer Polymer Control Test A Ink B Ink C Ink Ink Rub Resistance Receptor Cyan OD 0.14 0.04 0.04 0.04 Average Receptor Cyan OD 0.05 0.01 0.01 0.01 Average Standard Deviation Receptor Cyan b* 13.02 7.07 1.57 6.74 Average Receptor Cyan b* 1.57 0.54 0.6 0.55 Average Standard Deviation Coefficient of Average Static 0.41 0.39 0.39 0.31 Friction Coefficient of Friction Standard Deviation 0.01 0.04 0.01 0.03 Static Coefficient of Friction Average Kinetic 0.41 0.38 0.39 0.35 Coefficient of Friction Standard Deviation 0.01 0.01 0.00 0.03 Kinetic Coefficient of Friction Scratch Test Ink Removed by Scratch No No No No Glossy trace from Yes Yes Yes Yes scratch Degree of glossiness Moderate Moderate Moderate Mild Blocking SIR Rating at 60 C. 5.0 5.0 5.0 4.5 (Ink to Receptor) SIR Rating at 70 C. 5.0 5.0 5.0 4.0 SIR Rating at 80 C. 4.5 5.0 5.0 3.0 Blocking SIR Rating at 60 C. 5.0 5.0 5.0 4.5 (Ink to Ink) SIR Rating at 70 C. 5.0 5.0 5.0 4.5 SIR Rating at 80 C. 5.0 5.0 5.0 4.0

[0081] In addition, the shear viscosity of Ink Formulations Polymer A, B and C was significantly lower than that of the Control Ink. FIG. 9 shows the rheology curves for Polymer Inks A-C as well as the Control Ink. Rheological properties are somewhat dependent on the target application; however, a reduction in shear viscosity allows for the ink to flow more effectively. This reduction is typically beneficial in flexo and gravure ink applications. In addition, styrenic polymers can act as rheology additives/modifiers. As demonstrated, different styrenic polymers can be used and the rheology of the ink formulation can be modified and manipulated to meet the demands/needs of the targeted formulation without adversely affecting the overall print properties of the ink.

Example of Styrenic Polymer/UV-Active Monomer Formulations

[0082] FIG. 5 shows Process 500 for using a styrenic polymer product created via a depolymerization process (such as the one described in FIG. 1) to create a finish product, such as, but not limited to, an ink. First a styrenic polymer product is chosen in Styrenic Polymer Selection 510. The styrenic polymer is then solubilized in Solubilization Stage 520 to create a stable oligomer/monomer formulation. The resulting blend is then added in Formulation Stage 530 to create a finished product (such as an ink).

[0083] In an illustrative embodiment of the present process, styrenic polymers formed via depolymerization of polystyrene were identified for possible monomer solubilisation formulations. See Table 4.

TABLE-US-00004 TABLE 4 Styrenic Polymer Polymer E Polymer F MFI >50 >50 (Melt Flow Index as determined by ASTM DI238) Glass Transition Temperature.sub.initial 37.76 54.15 (As determined by differential scanning calorimetry) Glass Transition Temperature.sub.mid 63.87 63.32 (As determined by differential scanning calorimetry) Glass Transition Temperature.sub.end 89.98 72.52 (As determined by differential scanning calorimetry) Concentration of oligomer in 35-50 35-50 UV-Active monomer

[0084] The styrenic polymers were successfully solubilized into the UV-Active monomers with styrenic polymer concentrations ranging between and inclusive of 35 and 60% as shown in Table 5. In some preferred embodiments, the blends are stable with styrenic polymer concentrations ranging between and inclusive of 45 and 60%. In some more preferred embodiments, the blends are stable with styrenic polymer concentrations ranging between and inclusive of 50 and 60%.

[0085] FIG. 11 is a photograph of a styrenic polymer/UV-Active monomer formulation. The sample in the image is over 6 months old with no phasing/separation/destabilization occurring.

TABLE-US-00005 TABLE 5 Styrenic Polymer/UV-Active Monomer Solutions Formulation 1 2 3 4 5 6 7 8 9 Styrenic Polymer E 50 55 45 60 35 50 35 60 0 (Table 4) Styrenic Polymer F 0 0 0 0 0 0 0 0 50 (Table 4) 1,6-Hexanediol 0 0 0 0 0 50 65 40 0 Propoxylated 1,6- 50 45 55 40 65 0 0 0 0 Hexanediol diacrylate Ethoxylated 1,6- 0 0 0 0 0 0 0 0 50 Hexanediol Diacrylate Soluble Blend Formed Yes Yes Yes Yes Yes Yes Yes Yes Yes

[0086] In another set of trials, Polymer E was solubilized with 1,6-hexanediol and Trimethylolpropane Triacrylate. These formulations were then used to create various ink formulations as show in Table 6.

TABLE-US-00006 TABLE 6 UV-Curable Formulations with Standard Composition and with Styrenic Polymer Component Standard 5% 10% 15% Oligomer Polyester Acrylate 58.23 53.73 49.00 43.00 Reactive Diluent 1,6-Hexanediol diacrylate 23.49 23.09 23.09 24.09 Reactive Diluent Trimethylolpropane triacrylate 9.5 9.4 9.13 9.13 Photoinitiator 1 Irgacure 819 2.94 2.94 2.94 2.94 Photoinitiator 2 Irgacure 184 5.84 5.84 5.84 5.84 Styrenic Polymer Polymer E (Table 4) 0 5 10 15 Total 100 100 100 100

[0087] In these examples, the UV-curable formulations with the styrenic polymer performed similarly to the standard formulation in terms of the application on the substrate, UV-curing, and homogeneity of the resulting films on black coated paper.

[0088] While particular elements, embodiments and applications of the present invention have been shown and described, it will be understood, that the invention is not limited thereto since modifications can be made without departing from the scope of the present disclosure, particularly in light of the foregoing teachings. For example, the numerous embodiments demonstrate that different combinations of components are possible within the scope of the claimed invention, and these described embodiments are demonstrative and other combinations of the same or similar components can be employed to achieve substantially the same result in substantially the same way. Further, all of the claims are hereby incorporated by reference into the description of the preferred embodiments.