A modifying agent for recycled polystyrene materials

Abstract

This invention discloses a modifying agent for recycled polystyrene materials, relating to the field of recycled polystyrene materials, comprising: 3-8 parts of organically modified montmorillonite; 0.2-0.8 parts of organic peroxide; and 0.5-3 parts of styrene-based comonomers. The modified montmorillonite, organic peroxide, and styrene-based comonomers are compounded and melt-blended in situ to generate graft copolymers. Montmorillonite nanosheets are anchored at the interface between the two phases to form Janus particles, achieving compatibilization, reinforcement, and nucleation in one step. This significantly reduces modification costs and simultaneously improves the mechanical and foaming properties of the modifying agent, improves interfacial bonding, and features a simple and versatile process that effectively improves the utilization rate and added value of recycled materials.

Description

Technical Field

[0001] This invention relates to the field of polystyrene recycling technology, and more specifically to a modifying agent for polystyrene recycling. Background Technology

[0002] Polystyrene (PS) is one of the five major general-purpose plastics, widely used in appliance casings, packaging materials, and building insulation. With the continuous growth in plastic product consumption, the amount of polystyrene waste generated is also increasing year by year. Recycled polystyrene mainly comes from waste appliance casings, foam lunch boxes, and packaging liners, and its recycling is of great significance for resource conservation and environmental protection.

[0003] However, recycled polystyrene inevitably contains a certain proportion of polyolefin (polyethylene, PE; polypropylene, PP) impurities. Polystyrene and polyolefins are typical incompatible polymer systems, and direct blending can lead to significant phase separation and weak interfacial bonding in the finished product. Existing technologies typically use external block copolymers (such as SEBS and SEPS) as compatibilizers to improve compatibility, but these compatibilizers are expensive and require an addition amount as high as 5%-10%, significantly increasing the cost of recycling and modification and compressing profit margins.

[0004] Therefore, a modifying agent for recycled polystyrene is proposed, which utilizes mechanochemical effects to generate polystyrene-polyolefin graft copolymers in situ during melt blending, eliminating the need for expensive block copolymer compatibilizers, significantly reducing the cost of recycling modification, and simultaneously achieving compatibilization, strengthening, and nucleation functions. Summary of the Invention

[0005] The purpose of this invention is to provide a modifying agent for recycled polystyrene materials to solve the problem of high cost of recycling modification in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a modifying agent for recycled polystyrene materials, comprising, by weight parts:

[0007] 3-8 parts of organically modified montmorillonite;

[0008] 0.2-0.8 parts of organic peroxide;

[0009] 0.5 to 3 parts of styrene comonomers;

[0010] The modified additive is used for melt blending with recycled polystyrene. During this process, organic peroxides decompose to generate free radicals, which cause polystyrene and polyolefin impurities to undergo an in-situ grafting reaction to generate polystyrene-polyolefin graft copolymers.

[0011] After the organically modified montmorillonite is exfoliated into nanosheets, it is anchored at the interface between polystyrene and polyolefin by a polystyrene-polyolefin graft copolymer, forming Janus particles.

[0012] Furthermore, the interlayer spacing of the organically modified montmorillonite is ≥2.5 nm, and the cation exchange capacity is ≥90 meq / 100g.

[0013] Furthermore, the organic peroxide is selected from at least one of dicumyl peroxide or 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane.

[0014] Furthermore, the styrene-based comonomer is selected from at least one of styrene, α-methylstyrene, or maleic anhydride.

[0015] Application of a modified additive for recycled polystyrene materials in the preparation of injection molded products.

[0016] Furthermore, the modified additive is melt-blended with recycled polystyrene material and then injection molded.

[0017] Application of a modifier for recycled polystyrene materials in the preparation of foamed products.

[0018] Furthermore, the modified additive is melt-blended with recycled polystyrene material and then foamed and molded.

[0019] Compared with existing technologies, the present invention provides a modifier for polystyrene recycled materials, which uses organic modified montmorillonite, organic peroxide and styrene-based comonomers to generate graft copolymers in situ through melt blending, and anchors montmorillonite nanosheets at the interface of two phases to form Janus particles. This achieves compatibilization, reinforcement and nucleation in one step, greatly reducing the modification cost, and simultaneously improving the mechanical and foaming properties of the modifier, improving interfacial bonding. The process is simple and versatile, effectively improving the utilization rate and added value of recycled materials. Detailed Implementation

[0020] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below.

[0021] Organically modified montmorillonite: prepared by wet modification with octadecyltrimethylammonium chloride, with a stable interlayer spacing of 2.8 nm, a cation exchange capacity of 105 meq / 100g, a particle size ≤10 μm, and a moisture content ≤1.0%. Before use, it is dried in an oven at 105℃ for 2 h to remove adsorbed moisture and ensure smooth exfoliation during melt blending.

[0022] Organic peroxides: dicumyl peroxide (DCP), purity ≥98%, decomposition temperature 167℃; 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane (Bi25), purity ≥97%, decomposition temperature 179℃. Both peroxides are in powder form and should be stored at room temperature in a sealed container away from light.

[0023] Styrene-based comonomers: Styrene (St), purity ≥99%, colorless transparent liquid; α-methylstyrene (AMS), purity ≥98%, colorless liquid; maleic anhydride (MAH), purity ≥99%, white crystalline solid. All three monomers are reactive grafting monomers used to improve in-situ grafting efficiency.

[0024] Polystyrene recycled material: derived from waste household appliance shells, disposable foamed plastics, and packaging cushioning pads. After manual sorting, crushing, friction cleaning, centrifugal dehydration, and hot air drying, uniform particles with a particle size of 2–3 mm and a melt flow rate of 2.5 g / 10 min (200℃, 5 kg) are obtained. The main impurities are polyethylene (PE) and polypropylene (PP), and the content is precisely formulated according to experimental requirements and controlled between 5% and 20%.

[0025] Processing equipment: High-speed mixer (10 L capacity, adjustable speed 0–1500 rpm); twin-screw extruder (L / D ratio 44, screw diameter 35 mm, segmented temperature control); injection molding machine (clamping force 80 t, molding temperature 170–210℃); extrusion foaming unit (equipped with CO2 foaming agent injection system, foaming pressure 0.2–0.6 MPa adjustable).

[0026] Drying process: All recycled polystyrene materials are dried in an 80℃ constant temperature drying oven for 4 hours before use to ensure that the moisture content is ≤0.1% and to avoid defects such as bubbles, silver streaks, and degradation during processing.

[0027] Example 1:

[0028] Weigh the following components by mass parts:

[0029] 3 parts organic modified montmorillonite, 0.2 parts dicumyl peroxide (DCP), and 0.5 parts styrene monomer;

[0030] The dried organic-modified montmorillonite and dicumyl peroxide were added to a high-speed mixer, the chamber door was closed, the speed was set to 900 rpm, and the mixture was mixed at room temperature for 5 min to allow the organic peroxide to be fully adsorbed on the surface of the montmorillonite sheets and in the interlayer channels, forming a uniform loading system. Then, styrene monomer was added, and the speed was kept constant, and the mixture was continued for 3 min to allow the monomer to be uniformly coated on the surface of the montmorillonite-peroxide composite particles. After discharge, the mixture was sealed and stored to obtain a light yellow powdery modifier. The total amount added was 3.7% of the mass of the recycled polystyrene.

[0031] Take 100 parts of recycled polystyrene material, with polyolefin impurities of polypropylene (PP) precisely controlled at 5%, and dry it at 80℃ until the moisture content is ≤0.1%. Add the dried recycled material and the aforementioned modifying agents to the hopper of a twin-screw extruder in a specific ratio, using volumetric metering to ensure stable feeding. Twin-screw extruder process parameters are set as follows: feed section temperature 175℃, melt section temperature 195℃, reaction section temperature 205℃, homogenization section temperature 195℃, die head temperature 190℃; screw speed 400 rpm; vacuum port negative pressure 0.08 MPa to remove small molecule volatiles; die head orifice diameter 3 mm; water-cooled strip cutting; after cooling, the pellets are air-dried and packaged in sealed bags for later use.

[0032] The modified polystyrene recycled material granules were dried again at 80℃ for 2 h and then added to the injection molding machine barrel. The molding process was as follows: barrel temperature zone 1 180℃, zone 2 195℃, zone 3 200℃, nozzle 190℃; mold temperature 40℃; injection pressure 80 MPa; holding pressure 50 MPa; cooling time 15 s. Standard tensile, impact and bending specimens were obtained for performance testing.

[0033] This embodiment targets recycled materials with low oligoolefin impurity content. Without adding traditional compatibilizers, the organic peroxide decomposes upon heating to generate free radicals, triggering in-situ grafting of polystyrene and polypropylene chains to form a PS-PP graft copolymer. The organically modified montmorillonite is completely exfoliated into nanosheets under strong shear, anchored at the two-phase interface by the graft copolymer, forming a stable Janus particle structure. The material interface shows no obvious phase separation, the surface is smooth and without delamination, and the tensile strength reaches 28.5 MPa, while the notched impact strength reaches 6.8 kJ / m². 2 Compared to unmodified recycled materials, it is significantly improved, with moderate melt flow, fully meeting the mechanical and appearance requirements of injection molded products such as appliance shells and electrical accessories. The modification cost is reduced by more than 45% compared to the traditional process of adding 5% SEBS.

[0034] Example 2:

[0035] The following components are accurately weighed by mass: 5.5 parts of organically modified montmorillonite, 0.5 parts of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane (bis25), and 1.75 parts of α-methylstyrene.

[0036] Organically modified montmorillonite and bis-25 peroxide were added to a high-speed mixer and mixed at 900 rpm for 6 min to ensure that the peroxide was uniformly loaded into the montmorillonite layer structure. Then, α-methylstyrene was added and mixed for another 4 min to ensure that the monomer fully wetted the composite particles. The mixture was then discharged and sealed to obtain a modified additive with good flowability. The total amount added was 7.75% of the mass of the recycled polystyrene.

[0037] 100 parts of recycled polystyrene were melt-blended and granulated. The polyolefin impurity was polyethylene (PE), with the content precisely controlled at 12.5%. After drying, it was added to a twin-screw extruder along with the modifying agent. Process parameters: feed section 175℃, melting section 195℃, reaction section 205℃, homogenization section 195℃, die head 190℃; screw speed 450 rpm; vacuum devolatilization ensured that small molecules were completely discharged. After extrusion and granulation, uniform modified granules were obtained.

[0038] (1) Injection molding: Standard mechanical specimens were prepared using the same process as in Example 1 to test strength, toughness and dimensional stability. (2) Extrusion foaming molding: Modified particles were added to a foaming extruder, the foaming temperature was 165℃, the CO2 foaming agent injection pressure was 0.4 MPa, the die head pressure was stably controlled, and after cooling and shaping, a continuous foamed board with uniform and fine cells was obtained.

[0039] This embodiment is suitable for systems with medium polyolefin impurity content. The in-situ grafting reaction is thorough, resulting in significantly improved interfacial bonding. The montmorillonite nanosheets are completely exfoliated, and the interlayer spacing expands to 5.1 nm, demonstrating a significant nucleation effect. Injection-molded products exhibit a tensile strength of 30.8 MPa and a notched impact strength of 8.2 kJ / m². Foamed products show a reduced cell diameter to 55 μm and a foaming ratio increased to 24 times, more than double that of the unmodified material. Cell collapse and co-occurrence are absent, significantly improving thermal insulation and cushioning performance. This material can be used in insulation boards, packaging cushioning materials, and other fields. The entire process involves no expensive compatibilizers, reducing modification costs by more than 35%, while simultaneously achieving the triple effects of compatibilization, strengthening, and nucleation.

[0040] Example 3:

[0041] The following components are accurately weighed by mass: 8 parts of organic modified montmorillonite, 0.4 parts of dicumyl peroxide (DCP), 0.4 parts of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane (bis25), and 3 parts of maleic anhydride.

[0042] The three components, organic modified montmorillonite, DCP, and 25, were simultaneously added to a high-speed mixer and mixed at 900 rpm for 8 minutes to extend the mixing time and ensure uniform dispersion of the peroxide. Then, maleic anhydride was added and mixed for another 5 minutes to fully combine the anhydride monomer with the montmorillonite-peroxide system, resulting in a highly active modifier. The total amount added was 11.8% of the mass of the recycled polystyrene material.

[0043] 100 parts of recycled polystyrene material were taken, with polyolefin impurities consisting of polypropylene (PP), the content of which was precisely controlled at 20%, belonging to a high-impurity, poorly compatible system. After drying, it was blended with modifying agents and added to a twin-screw extruder to improve screw shear strength. The speed was set at 500 rpm, and the temperature range was consistent with that in Example 1. Vacuum devolatilization was used to strengthen the reaction and ensure complete reaction with no residual small molecules. Injection molding was performed using a high-temperature, high-pressure injection molding process to increase injection and holding pressure, allowing the high-viscosity material to fully fill the mold and obtain high-strength injection molded specimens. The rigidity, toughness, and interfacial compatibility were then tested.

[0044] This embodiment achieves highly efficient compatibilization even with recycled materials containing 20% ​​high-polyolefin impurities. Maleic anhydride significantly improves in-situ grafting efficiency, while the dual peroxide system ensures continuous and stable free radical generation. Montmorillonite nanosheets are completely exfoliated and stably anchored at the interface, increasing the interlayer spacing to 5.8 nm, forming a dense interface layer that prevents phase separation. The material's tensile strength and impact strength are simultaneously improved, elongation at break is increased by approximately four times, and dimensional stability is excellent. No pretreatment to separate impurities is required, significantly simplifying the process and reducing recycling costs.

[0045] Example 4:

[0046] The following components are accurately weighed by mass: 4 parts of organic modified montmorillonite, 0.3 parts of dicumyl peroxide (DCP), and 1 part of styrene monomer.

[0047] The dried organic-modified montmorillonite and dicumyl peroxide were added to a high-speed mixer, the chamber door was closed, the speed was set to 900 rpm, and the mixture was mixed at room temperature for 5 minutes to allow the organic peroxide to be uniformly adsorbed into the montmorillonite layers and interlayer structure. Then, styrene monomer was added, and the speed was kept constant, and the mixture was continued for 3 minutes to allow the styrene monomer to be uniformly coated on the surface of the montmorillonite-peroxide composite particles. The material was discharged, sealed and stored to obtain a low-addition modifier. The total addition amount was only 5.3% of the mass of the recycled polystyrene, which is much lower than the 5%-10% addition amount of traditional compatibilizers.

[0048] Take 100 parts of recycled polystyrene material, with polyethylene (PE) as the polyolefin impurity, and precisely control its content to 10%. Dry it at 80℃ until the moisture content is ≤0.1%. Add the dried recycled material and the aforementioned modifying agents simultaneously to the hopper of a twin-screw extruder, using volumetric metering to ensure stable feeding. Twin-screw extruder process parameters: feed section temperature 175℃, melt section temperature 195℃, reaction section temperature 205℃, homogenization section temperature 195℃, die head temperature 190℃; screw speed 420 rpm; vacuum port negative pressure 0.08 MPa to fully remove small molecule byproducts generated during the reaction; die head orifice diameter 3 mm, water-cooled strip cutting, and the pellets are dried with cold air and then sealed for later use.

[0049] The modified recycled material granules were dried again at 80℃ for 2 hours and then added to an injection molding machine for molding. The injection molding process parameters were as follows: barrel zone 1 175℃, zone 2 190℃, zone 3 195℃, nozzle 185℃; mold temperature 35℃; injection pressure 75 MPa; holding pressure 45 MPa; cooling time 12 s. Standard mechanical test specimens were obtained for tensile, impact, and flow performance testing.

[0050] This embodiment achieves effective modification with the lowest additive dosage, further reducing modification costs by more than 50% compared to traditional processes. Organic peroxides trigger in-situ grafting reactions to generate PS-PE graft copolymers. Montmorillonite nanosheets are uniformly dispersed at the interface between the two phases and form Janus particles. The interface compatibility is good, with no obvious delamination or cracking, meeting the requirements for use in general injection molded products.

[0051] Example 5:

[0052] The following components are accurately weighed by mass: 4 parts of organically modified montmorillonite, 0.4 parts of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane (bis25), and 1.5 parts of α-methylstyrene.

[0053] Organically modified montmorillonite and bis-25 peroxide were added to a high-speed mixer and mixed at 900 rpm for 6 min to fully load the peroxide onto the montmorillonite layer structure. Then, α-methylstyrene was added, and the mixture was kept at the same speed and mixed for another 4 min to uniformly wet the composite particles with the monomers. The mixture was then discharged and sealed to obtain a high-flowability modified additive.

[0054] 100 parts of recycled polystyrene material, with PP as the polyolefin impurity and its content precisely controlled at 8%, were dried at 80°C until the moisture content was ≤0.1%. This was then blended with modifying agents and fed into a twin-screw extruder. To improve melt flowability, the reaction zone temperature was slightly increased to 210°C, and the screw speed was set to 480 rpm to enhance shear dispersion. The remaining temperature range remained consistent with Example 1, with a vacuum negative pressure of 0.08 MPa. High-flowability modified granules were obtained after extrusion granulation.

[0055] Thin-walled molds with a cavity thickness of 1.2 mm were used for injection molding. The injection process was as follows: barrel temperature 185°C in zone 1, 200°C in zone 2, 205°C in zone 3, and nozzle temperature 195°C; mold temperature 30°C; injection pressure 90 MPa; injection speed adjusted to high speed; holding pressure 55 MPa; and cooling time shortened to 10 s. Thin-walled shells and ultra-thin structural parts were prepared, and the mold filling performance and mechanical properties were tested.

[0056] In this embodiment, the melt flow rate is moderate, the thin-walled parts are completely filled with mold without missing glue or weld lines; the nano-montmorillonite plays a heterogeneous nucleation role, which accelerates the cooling and shaping of the product and improves production efficiency; the interface is tightly bonded, the thin-walled parts have good impact resistance, improve the flowability of recycled materials, and the thin walls are not easy to break, so it can be used for high-end recycled products such as ultra-thin home appliance parts and electronic shells.

[0057] Example 6:

[0058] Accurately weigh the following components by weight: 6 parts organic modified montmorillonite, 0.5 parts bis25 peroxide, and 2 parts maleic anhydride. Add the organic modified montmorillonite and bis25 peroxide to a high-speed mixer and mix at 900 rpm for 7 minutes to ensure uniform dispersion of the peroxide. Then add maleic anhydride and continue mixing for 5 minutes to fully combine the anhydride monomer with the montmorillonite-peroxide system. Discharge and seal to obtain the weather-resistant modified additive.

[0059] Take 100 parts of recycled polystyrene material, with the PE impurity content precisely controlled at 15%, and dry it at 80℃ until the moisture content is ≤0.1%. Add it together with the modifying agent into a twin-screw extruder. The process parameters are exactly the same as in Example 2: feed section 175℃, melting section 195℃, reaction section 205℃, homogenization section 195℃, die head 190℃; screw speed 450 rpm; after vacuum devolatilization, extrude and granulate to obtain weather-resistant modified granules.

[0060] After drying the modified particles at 80℃ for 2 h, they were injection molded to prepare standard tensile and impact test specimens. The specimens were placed in an ultraviolet aging test chamber and aged continuously for 168 h under ultraviolet wavelength of 340 nm, irradiance of 0.51 W / m², and temperature of 60℃. The retention rate of mechanical properties before and after aging was tested.

[0061] Test results show that montmorillonite nanosheets can effectively block ultraviolet rays and reduce photo-oxidative degradation of polymer chains; maleic anhydride enhances interfacial bonding and strengthens the structural stability of the material; after aging, the tensile strength is 25.1 MPa and the notched impact strength is 6.2 kJ / m², and the weather resistance is significantly improved compared with the unmodified material, making it suitable for outdoor packaging, garden accessories and other applications.

[0062] Comparative Example 1:

[0063] Weigh out the following by weight: 5.5 parts of organically modified montmorillonite and 1.75 parts of α-methylstyrene; the mixing process is the same as in Example 2, without adding any organic peroxides.

[0064] Organically modified montmorillonite and α-methylstyrene were added to a high-speed mixer and mixed at 900 rpm for 10 min. After uniform mixing, the mixture was discharged and sealed to obtain a comparative additive. 100 parts of recycled polystyrene material with a PE impurity content of 12.5% ​​were dried at 80℃ to a moisture content ≤0.1% and added to a twin-screw extruder along with the comparative additive. The extrusion process parameters were exactly the same as in Example 2: feed section 175℃, melt section 195℃, reaction section 205℃, homogenization section 195℃, die head 190℃; screw speed 450 rpm; after vacuum devolatilization, the material was extruded and granulated. The injection molding process was the same as in Example 2 to obtain test samples.

[0065] The results showed that no free radicals were generated in the system, which could not trigger the in-situ grafting reaction between polystyrene and polyolefin. There was no effective bonding between the PS and PE phases, and the phase separation phenomenon was severe. Montmorillonite was only a physical filler and could not be anchored at the two-phase interface. It was unevenly dispersed, the interfacial bonding force was extremely weak, the mechanical properties were only slightly improved, and the product surface was rough, easy to delaminate and easy to break, which could not meet the actual use requirements.

[0066] Comparative Example 2:

[0067] Weigh out the following components by mass: 0.5 parts dicumyl peroxide and 1.75 parts α-methylstyrene. Mix them thoroughly and then blend them with the recycled material.

[0068] Dicumyl peroxide and α-methylstyrene were added to a high-speed mixer and mixed at 900 rpm for 5 min to obtain a comparative additive free of montmorillonite. 100 parts of recycled polystyrene containing 12.5% ​​PE impurities were dried and blended with the aforementioned comparative additive. Test samples were prepared using the same twin-screw extrusion and injection molding process as in Example 2.

[0069] The results show that the system can achieve a certain degree of in-situ grafting compatibility through peroxide and comonomer, and the compatibility is improved compared with the unmodified material; however, due to the lack of organic modified montmorillonite, there is no nano-reinforcement and heterogeneous nucleation effect, the tensile strength and rigidity of the material are insufficient, and the dimensional stability is poor; when used for foaming, there are insufficient nucleation sites for the cells, the cells are large and unevenly distributed, the foaming ratio is low, and the reinforcement and nucleation functions cannot be achieved.

[0070] Comparative Example 3:

[0071] Weigh out the following components by weight: 5.5 parts of organically modified montmorillonite and 0.5 parts of dicumyl peroxide, mix them together, and then blend them with the recycled material.

[0072] Organically modified montmorillonite and dicumyl peroxide were added to a high-speed mixer and mixed at 900 rpm for 6 min to obtain a comparative additive free of styrene comonomers. 100 parts of recycled polystyrene containing 12.5% ​​PE impurities were dried, co-extruded, and the extrusion and injection molding processes were the same as in Example 2 to obtain test samples.

[0073] The results show that the system lacks comonomers, the efficiency of in-situ grafting reaction is greatly reduced, and free radicals easily cause material degradation rather than effective grafting; polystyrene and polyolefin have poor compatibility, weak interfacial bonding force, insufficient montmorillonite peeling degree, and cannot stably anchor the interface; the improvement of mechanical properties is not obvious, the compatibilization effect is far lower than that of Example 2, and it cannot achieve the technical effect of efficient compatibilization and simultaneous enhancement.

[0074] Comparative Example 4:

[0075] Using the same formulation as in Example 2, but instead of a single screw extruder (length-to-diameter ratio 28, speed 200 rpm), the mixture was blended and granulated.

[0076] The modified additive was prepared according to the formulation of Example 2 and blended with 100 parts of recycled polystyrene containing 12.5% ​​PE impurities. The mixture was then added to a single-screw extruder for melt blending and granulation. The processing temperature was the same as in Example 2: 175°C for the feed section, 195°C for the melt section, 205°C for the reaction section, 195°C for the homogenization section, and 190°C for the die head; the screw speed was 200 rpm; after extrusion granulation, the same process was used for injection molding to obtain test samples.

[0077] The results showed that the shear force of the single-screw extruder was insufficient, and the organically modified montmorillonite could not be completely exfoliated into nanosheets under shear action, with an interlayer spacing of only 3.5 nm and poor dispersion uniformity. At the same time, the low shear caused the in-situ grafting reaction to be insufficient, the interfacial bonding force between the two phases was weak, and the mechanical properties and melt stability of the material were significantly lower than those of the twin-screw system.

[0078] The performance of the samples prepared in Examples 1 to 6 and Comparative Examples 1 to 4 is summarized in the table below.

[0079] Table 1 Sample Performance Table

[0080] Group Tensile strength (MPa) <![CDATA[Izod impact strength (kJ / m 2 )]]> Elongation at break (%) Melt flow rate (g / 10min) Montmorillonite interlayer spacing (nm) Expansion ratio (times) Cell diameter (μm) Unmodified recycled PS 17.8-20.1 2.5-2.8 5.0-6.5 14.5-18.0 - 10-12 150-200 Example 1 28.5 6.8 16.2 11.5 4.2 - - Example 2 30.8 8.2 21.5 9.8 5.1 24 55 Example 3 32.2 8.8 24.3 8.5 5.8 - - Example 4 27.3 6.2 15.1 12.1 4.0 - - Example 5 26.8 5.9 14.3 13.2 3.9 - - Example 6 29.5 7.5 18.6 10.6 4.8 - - Comparative Example 1 22.3 3.8 9.5 14.2 3.2 - - Comparative Example 2 24.1 4.5 11.2 12.8 - - - Comparative Example 3 26.5 5.6 14.8 11.2 4.5 - - Comparative Example 4 25.8 4.9 12.5 12.5 3.5 - -

[0081] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above description is illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A modifying agent for recycled polystyrene materials, characterized in that, By weight, including: 3-8 parts of organically modified montmorillonite; 0.2-0.8 parts of organic peroxide; 0.5 to 3 parts of styrene comonomers; The modified additive is used for melt blending with recycled polystyrene. During this process, organic peroxides decompose to generate free radicals, which cause polystyrene and polyolefin impurities to undergo an in-situ grafting reaction to generate polystyrene-polyolefin graft copolymers. After the organically modified montmorillonite is exfoliated into nanosheets, it is anchored at the interface between polystyrene and polyolefin by a polystyrene-polyolefin graft copolymer, forming Janus particles.

2. The modifier for recycled polystyrene materials according to claim 1, characterized in that, The organically modified montmorillonite has an interlayer spacing of ≥2.5 nm and a cation exchange capacity of ≥90 meq / 100g.

3. The modifier for recycled polystyrene materials according to claim 1, characterized in that, The organic peroxide is selected from at least one of dicumyl peroxide or 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane.

4. The modifier for recycled polystyrene materials according to claim 1, characterized in that, The styrene-based comonomer is selected from at least one of styrene, α-methylstyrene, or maleic anhydride.

5. The use of the modifier for recycled polystyrene as described in any one of claims 1-4 in the preparation of injection molded articles.

6. The application according to claim 5, characterized in that, The modified additives are melt-blended with recycled polystyrene and then injection molded.

7. The use of the modifier for recycled polystyrene as described in any one of claims 1-4 in the preparation of foamed products.

8. The application according to claim 7, characterized in that, The modified additive is melt-blended with recycled polystyrene and then foamed into shape.