Assistant for modifying polystyrene reclaimed material and preparation method of expandable polystyrene beads

Abstract

The invention relates to the technical field of high polymer material recycling and reusing, in particular to an auxiliary agent of a modified polystyrene reclaimed material and a preparation method of expandable polystyrene beads. The invention provides an auxiliary agent of a modified polystyrene reclaimed material. The auxiliary agent comprises 1-1.5 parts of a nucleating agent, 1-2 parts of a modifier and 0.5-3 parts of a lubricant, the modifier comprises one or more of an OPS (oriented polystyrene) reclaimed material, a styrene-maleic anhydride copolymer, an ethylene-vinyl acetate copolymer and a POE (polyolefin elastomer). The auxiliary agent can enable the final product to have relatively strong compression strength and flexibility, uniform cell density and light weight.

Description

Technical Field

[0001] The invention relates to the technical field of polymer material recycling and reuse, and in particular to an auxiliary agent for modified polystyrene recycled material and a preparation method of expandable polystyrene beads. Background Art

[0002] Polystyrene (PS) is a polymer obtained by polymerization of styrene monomers. It is a colorless and transparent thermoplastic plastic. By adding a foaming agent, expandable polystyrene (EPS) can be prepared. The product has the characteristics of acid and alkali resistance, light weight, good cushioning and shock resistance, and thermal insulation performance. It is used to produce insulation boards, sound insulation boards and packaging materials. Expandable polystyrene is widely used in packaging and decorative materials such as construction engineering, food, fruits and vegetables, electrical appliances and tool manufacturing.

[0003] However, during the processing of expanded polystyrene, some foam waste, scraps after cutting and other waste materials will be generated. In addition, the expanded polystyrene used for packaging will also become waste after one-time use. The amount of foam packaging boxes has exceeded that of the construction industry, resulting in the generation of a large amount of waste expanded polystyrene materials. Expanded polystyrene materials are large in size, light in weight and chemically stable. Because they are difficult to degrade and form serious "white pollution" after being discarded, which causes great harm to the ecological environment, the recycling of expanded polystyrene materials has become a hot spot in environmental protection. By recycling and reusing them, waste polystyrene can be turned into treasure, and waste polystyrene recycled materials can be converted into products with economic value. This is not only conducive to the recycling of resources, but also can better solve environmental pollution problems. It is an important part of the green development path.

[0004] At present, the existing process methods in the market use polystyrene recycled materials to produce expandable polystyrene beads, which are also used in some applications. However, since the waste polystyrene packaging is repeatedly heated and melted during the recycling and granulation process, the polystyrene resin molecular chain is broken and the molecular weight is greatly reduced. Some new polystyrene resin materials need to be added during production to meet the product performance requirements. If all polystyrene recycled materials are used for production, the performance of the finished product will decrease and fail to meet the product requirements. Summary of the invention

[0005] In view of this, the object of the present invention is to provide an auxiliary agent for modified polystyrene recycled material and a method for preparing expandable polystyrene beads. The auxiliary agent can make the final product have strong compressive strength, flexibility, uniform cell density and light weight.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides an auxiliary agent for modified polystyrene recycled material, which comprises 1 to 1.5 parts of a nucleating agent, 1 to 2 parts of a modifier, and 0.5 to 3 parts of a lubricant in terms of weight parts;

[0008] The modifier includes one or more of OPS oriented polystyrene recycled material, styrene-maleic anhydride copolymer, ethylene-vinyl acetate copolymer and POE polyolefin elastomer.

[0009] Preferably, the nucleating agent includes one or more of talc, nano calcium carbonate and graphite.

[0010] Preferably, the lubricant comprises low molecular weight polyethylene wax and / or white oil;

[0011] The number average molecular weight of the low molecular weight polystyrene wax is 1000-2000.

[0012] Preferably, it also includes one or more of flame retardants, antioxidants, ultraviolet absorbers and masterbatches.

[0013] Preferably, the flame retardant includes one or more of octabromoether, methyl octabromoether, chlorinated paraffin, brominated SBS and tetrabromobisphenol A.

[0014] Preferably, the antioxidant includes one or more of antioxidant 1010, antioxidant 1098 and antioxidant 1078.

[0015] The present invention also provides a method for preparing expandable polystyrene beads, comprising the following steps:

[0016] The polystyrene recycled material particles and the additive are mixed and kneaded, and then melt-extruded and granulated in sequence to obtain beads, and a foaming agent is added during the melt-extrusion process;

[0017] mixing the beads, a coating agent and an antistatic agent to obtain the expandable polystyrene beads;

[0018] The auxiliary agent is the auxiliary agent described in the above technical solution.

[0019] Preferably, the mass ratio of the polystyrene recycled material particles to the additive is (91-94):(6-9).

[0020] Preferably, the foaming agent includes one or more of n-pentane, isopentane and n-butane;

[0021] The ratio of the mass of the foaming agent to the total mass of the polystyrene recycled material particles and the auxiliary agent is (5.5-6.5):100.

[0022] Preferably, the temperature of the melt extrusion is 140 to 260°C;

[0023] The coating agent includes one or more of zinc stearate, mono- and di-stearate glyceryl, tri-stearate glyceryl and polyethylene glycol; the mass ratio of the coating agent to the polystyrene recycled material particles is (0.3-0.7): (93-100);

[0024] The antistatic agent comprises one or more of ethoxy lauryl amide, octadecyl dimethyl hydroxyethyl ammonium nitrate, bis(β-hydroxyethyl) coconut amine and alkyl ether phosphate potassium salt TXP-100; the mass ratio of the antistatic agent to the polystyrene recycled material particles is (0.05-0.06): (95-100).

[0025] The present invention provides an auxiliary agent for modifying polystyrene recycled materials, which comprises 1 to 1.5 parts of a nucleating agent, 1 to 2 parts of a modifier, and 0.5 to 3 parts of a lubricant in parts by weight; the modifier comprises one or more of OPS oriented polystyrene recycled materials, styrene-maleic anhydride copolymer, ethylene-vinyl acetate copolymer, and POE polyolefin elastomer. The auxiliary agent of the present invention can make polystyrene recycled materials produce graft crosslinking under high temperature, and the molecular chains in the polymer are staggered and connected together to form a more stable and tough network structure. In order to increase the compressive strength and flexibility of the product, the obtained product has uniform pore density, light weight, and high strength. DETAILED DESCRIPTION

[0026] The present invention provides an auxiliary agent for modified polystyrene recycled material, which comprises 1 to 1.5 parts of a nucleating agent, 1 to 2 parts of a modifier, and 0.5 to 3 parts of a lubricant in terms of weight parts;

[0027] The modifier includes one or more of OPS oriented polystyrene recycled material, styrene-maleic anhydride copolymer, ethylene-vinyl acetate copolymer and POE polyolefin elastomer.

[0028] According to the mass percentage, the auxiliary agent of the modified polystyrene recycled material of the present invention includes 1 to 1.5 parts of nucleating agent, preferably 1 to 1.2 parts. In the present invention, the nucleating agent preferably includes one or more of talcum powder, nano calcium carbonate and graphite. When the nucleating agent is two or more of the above specific selections, the present invention does not have any special restrictions on the ratio of the above specific substances, and can be mixed in any ratio. In the present invention, the particle size of the nucleating agent is preferably ≤16μm, more preferably ≤8μm. In an embodiment of the present invention, the amount of the nucleating agent can be 1.2 parts or 1 part, and the type of the nucleating agent can be ultrafine talcum powder with a particle size of 13μm or nano calcium carbonate with a particle size of 8μm.

[0029] In the present invention, after the nucleating agent is added, it is evenly dispersed inside the product particles during the extrusion process, and low potential energy points are formed around the nucleating agent during the injection of the foaming agent, so that the foaming agent aggregates and is evenly distributed in the product beads.

[0030] Based on the mass fraction of the nucleating agent, the auxiliary agent of the modified polystyrene recycled material of the present invention includes 1 to 2 parts of the modifier, preferably 1.2 to 1.5 parts. In the present invention, the modifier includes one or more of OPS oriented polystyrene recycled material, styrene-maleic anhydride copolymer, ethylene-vinyl acetate copolymer and POE polyolefin elastomer. When the modifier is two or more of the above specific selections, the present invention does not have any special restrictions on the ratio of the above specific substances, and can be mixed in any ratio. In an embodiment of the present invention, the amount of the modifier can be 1.2 parts, 1.5 parts or 2 parts, and the type of the modifier can be styrene-maleic anhydride copolymer, ethylene-vinyl acetate copolymer, OPS oriented polystyrene recycled material or POE polyolefin elastomer.

[0031] In the present invention, the modifier generates graft crosslinking with the linear polystyrene under the high temperature of the extruder.

[0032] The additive of the modified polystyrene recycled material of the present invention includes 0.5 to 3 parts of lubricant, based on the mass fraction of the nucleating agent. In the present invention, the lubricant preferably includes low molecular weight polyethylene wax and / or white oil, and the number average molecular weight of the low molecular weight polyethylene wax is preferably 1000 to 2000; when the lubricant is low molecular weight polystyrene wax and white oil, the present invention does not have any special restrictions on the amount of the low molecular weight polystyrene wax and white oil, and they can be mixed in any ratio. In an embodiment of the present invention, the amount of the lubricant can be 0.5 parts or 3 parts, and the type of the lubricant can be a low molecular weight polyethylene wax with a number average molecular weight of 1000.

[0033] In the present invention, the lubricant can make other components in the auxiliary agent be dispersed better.

[0034] In the present invention, the additives of the modified polystyrene recycled material preferably include one or more of a flame retardant, an antioxidant, an ultraviolet absorber and a masterbatch.

[0035] The additive of the modified polystyrene recycled material of the present invention includes 1 to 2 parts of flame retardant, preferably 1.5 parts, based on the mass fraction of the nucleating agent. In the present invention, the flame retardant preferably includes one or more of octabromoether, methyl octabromoether, chlorinated paraffin, brominated SBS and tetrabromobisphenol A. When the flame retardant is two or more of the above specific selections, the present invention does not have any special restrictions on the ratio of the above specific substances, and can be mixed in any ratio. In an embodiment of the present invention, the amount of the flame retardant can be 0 parts or 1.5 parts; the type of the flame retardant can be methyl octabromoether.

[0036] In the present invention, the flame retardant acts as a functional auxiliary agent that imparts flame retardancy to the flammable polymer, thereby inhibiting the spread of flame and reducing flammability.

[0037] The auxiliary agent of the modified polystyrene recycled material of the present invention includes 0.2 to 0.8 parts of antioxidant, preferably 0.5 parts, based on the mass fraction of the nucleating agent. In the present invention, the antioxidant preferably includes one or more of antioxidant 1010, antioxidant 1098 and antioxidant 1078. When the antioxidant is two or more of the above specific selections, the present invention does not have any special restrictions on the ratio of the above specific substances, and can be mixed in any ratio. In an embodiment of the present invention, the amount of the antioxidant can be 0 parts or 0.5 parts, and the type of the antioxidant can be antioxidant 1010 or antioxidant 1098.

[0038] In the present invention, the antioxidant functions to capture free radicals in the polymer material system through its polyhedral hindered phenol structure, thereby effectively preventing the thermal oxidation degradation of the polymer material during the long-term aging process.

[0039] In terms of the mass fraction of the nucleating agent, the auxiliary agent of the modified polystyrene recycled material of the present invention includes 0.1 to 0.4 parts of ultraviolet absorbers, preferably 0.3 parts. In the present invention, the ultraviolet absorber preferably includes one or more of o-hydroxybenzoic acid phenyl ester, 2-(2'-hydroxy-5'-methylphenyl) benzotriazole and 2-hydroxy-4-n-octyloxybenzophenone. When the ultraviolet absorber is two or more of the above-mentioned specific selections, the present invention does not have any special restrictions on the ratio of the above-mentioned specific substances, and can be mixed in any ratio. In an embodiment of the present invention, the type of the ultraviolet absorber can be 2-hydroxy-4-n-octyloxybenzophenone, and the amount of the ultraviolet absorber can be 0 parts or 0.3 parts.

[0040] The additives of the modified polystyrene recycled material of the present invention include 1 to 3.5 parts of masterbatch, preferably 3 parts, based on the mass fraction of the nucleating agent. The present invention does not have any special limitation on the masterbatch, and any type familiar to those skilled in the art can be used. In an embodiment of the present invention, the type of the masterbatch can be titanium dioxide, color masterbatch or graphite masterbatch; the amount of the masterbatch can be 3 parts or 1.2 parts.

[0041] The present invention also provides a method for preparing expandable polystyrene beads, comprising the following steps:

[0042] The polystyrene recycled material particles and the additives are mixed and kneaded, and then melt-extruded and granulated in sequence to obtain beads, and a foaming agent is added during the melt-extrusion process;

[0043] mixing the beads, a coating agent and an antistatic agent to obtain the expandable polystyrene beads;

[0044] The auxiliary agent is the auxiliary agent described in the above technical solution.

[0045] The invention mixes polystyrene recycled material particles and auxiliary agents for kneading, and then sequentially performs melt extrusion and granulation to obtain beads, wherein a foaming agent is added during the melt extrusion process.

[0046] In the present invention, the polystyrene recycled material particles are preferably prepared by recycling and granulating waste polystyrene. The present invention has no special limitation on the recycling and granulation process, and the process well known to those skilled in the art can be used. Alternatively, the polystyrene recycled material particles are preferably prepared by purchasing commercially available processed polystyrene particles.

[0047] Before the mixing, the present invention preferably washes the polystyrene recycled material particles; the present invention does not have any special limitation on the washing process, and adopts a process well known to those skilled in the art to ensure that the mixed impurities and other types of plastics are removed, so as to ensure that the purity of the polystyrene recycled material is above 99% and the ash content is less than 1%.

[0048] The present invention does not have any special limitation on the mixing process, and the mixing process can be carried out by a process well known to those skilled in the art. In an embodiment of the present invention, the mixing is carried out in a mixer.

[0049] In the present invention, the mass ratio of the polystyrene recycled material particles to the additive is preferably (91-94): (6-9). In an embodiment of the present invention, the mass ratio of the polystyrene recycled material particles to the additive can be 93:7.9, 91:6.7, 93:7.7 or 91:7.5.

[0050] In the present invention, the temperature of the melt extrusion is preferably 140-260° C. In an embodiment of the present invention, the temperature of the melt extrusion is preferably divided into four zones, and the temperatures of the four zones from front to back may be 140° C., 170° C., 260° C. and 190° C., or 150° C., 190° C., 210° C. and 200° C., or 140° C., 190° C., 210° C. and 185° C., or 140° C., 190° C., 260° C. and 220° C.

[0051] In the present invention, the foaming agent is preferably one or more of n-pentane, isopentane and n-butane, and n-pentane is more preferred. When the foaming agent is two or more of the above specific selections, the present invention has no special restrictions on the ratio of the above specific substances, and they can be mixed in any ratio.

[0052] In the present invention, the mass ratio of the foaming agent to the total mass of the polystyrene recycled material particles and the auxiliary agent is preferably (5.5-6.5): 100, more preferably (5.8-6.2): ​​100. In an embodiment of the present invention, the mass ratio of the foaming agent to the polystyrene recycled material particles may be 5.6: 100.9, 5.8: 97.7, 5.5: 100.7 or 6: 95.5.

[0053] In the present invention, the foaming agent is preferably injected at the rear end of an extruder for melt extrusion and then extruded through the die holes on the die plate.

[0054] The present invention has no special limitation on the granulation process, and the process well known to those skilled in the art can be used. In an embodiment of the present invention, the granulation is preferably obtained by rotary cutting and cooling granulation with an underwater pelletizer.

[0055] After the granulation is completed, the present invention preferably further comprises sieving through a vibrating screen to obtain beads with a particle size of 0.6 to 1.2 mm.

[0056] After obtaining the beads, the present invention mixes the beads, a coating agent and an antistatic agent to obtain the expandable polystyrene beads.

[0057] In the present invention, the coating agent preferably includes one or more of zinc stearate, mono- and di-stearate glyceryl, tri-stearate glyceryl and polyethylene glycol, and more preferably includes zinc stearate; when the coating agent is two or more of the above specific selections, the present invention does not have any special restrictions on the ratio of the above specific substances, and can be mixed in any ratio. In an embodiment of the present invention, the coating agent can be zinc stearate or mono-stearate glyceryl. In the present invention, the mass ratio of the coating agent to the polystyrene recycled material particles is preferably (0.3-0.7): (93-100), and more preferably (0.4-0.7): (93-100). In an embodiment of the present invention, the mass ratio of the coating agent to the polystyrene recycled material particles can be 0.4:93, 0.4:91 or 0.4:88.

[0058] In the present invention, the antistatic agent preferably includes one or more of ethoxy lauryl amide, octadecyl dimethyl hydroxyethyl ammonium nitrate, bis (β-hydroxyethyl) coconut oil amine and alkyl ether phosphate potassium salt TXP-100, and more preferably includes a quaternary ammonium antistatic agent; when the antistatic agent is two or more of the above-mentioned specific selections, the present invention does not have any special restrictions on the ratio of the above-mentioned specific substances, and can be mixed in any ratio. In an embodiment of the present invention, the antistatic agent can be a quaternary ammonium antistatic agent or octadecyl dimethyl hydroxyethyl ammonium nitrate. In the present invention, the mass ratio of the antistatic agent to the polystyrene recycled material particles is preferably (0.05-0.06): (95-100), and more preferably 0.06:95. In an embodiment of the present invention, the mass of the antistatic agent to the polystyrene recycled material particles can be 0.06:95.

[0059] In the present invention, the mixing is preferably carried out under stirring conditions. The present invention does not have any special limitation on the stirring process, and the stirring process may be carried out using a process well known to those skilled in the art.

[0060] After the mixing is completed, the present invention preferably further comprises packaging. The present invention does not have any special limitation on the packaging process, and the packaging process may be carried out using a process well known to those skilled in the art.

[0061] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0062] Example 1

[0063] The additive composition (by weight): 1.2 parts of ultrafine talc powder (particle size is 13 μm), 1.5 parts of methyl octabromoether, 0.5 parts of antioxidant 1098, 1.2 parts of POE polyolefin elastomer, 0.5 parts of low molecular weight polyethylene wax (number average molecular weight is 1000) and 3 parts of masterbatch (graphite masterbatch);

[0064] Preparation method of expandable polystyrene beads:

[0065] Use commercially available polystyrene recycled material particles;

[0066] 93 parts by weight of the polystyrene recycled material particles, 1.2 parts by weight of ultrafine talc, 1.5 parts by weight of methyl octabromoether, 0.5 parts by weight of antioxidant 1098, 1.2 parts by weight of POE polyolefin elastomer, 0.5 parts by weight of low molecular weight polyethylene wax (number average molecular weight is 1000) and 3 parts by weight of masterbatch are fully mixed in a mixer to obtain a mixture;

[0067] The screw extruder is heated by heat-conducting oil, and the specific segmented heating temperatures of the screw extruder are 140° C., 170° C., 260° C. and 190° C. The mixed material is transported to the screw extruder for melt blending, and 5.6 parts by weight of n-pentane foaming agent is injected into the rear end of the extruder, and then extruded through the die hole on the template, and the mixture is cut by an underwater pelletizer for cooling and granulation, separated by a centrifuge, and sieved by a vibrating screen to obtain beads with a particle size of 1.0 mm;

[0068] The beads with a particle size of 1.0 mm, 0.06 parts by weight of octadecyl dimethyl hydroxyethyl ammonium nitrate antistatic agent and 0.4 parts by weight of glyceryl monostearate coating agent are mixed and stirred until fully mixed and uniform to obtain expandable polystyrene beads (expandable graphite flame retardant polystyrene beads, mainly used in building exterior walls and color steel sandwich panels).

[0069] Example 2

[0070] Additive composition (by weight): 1.2 parts of nano calcium carbonate (particle size 8 μm), 0.5 parts of antioxidant 1010, 1.5 parts of OPS oriented polystyrene recycled material, 0.5 parts of low molecular weight polyethylene wax (number average molecular weight 2000), 3 parts of color masterbatch;

[0071] Preparation method of expandable polystyrene beads:

[0072] Use commercially available polystyrene recycled material particles;

[0073] 91 parts by weight of the polystyrene recycled material particles, 1.2 parts by weight of nano calcium carbonate, 0.5 parts by weight of antioxidant 1010, 1.5 parts by weight of OPS oriented polystyrene recycled material, 0.5 parts by weight of low molecular weight polyethylene wax (number average molecular weight is 2000) and 3 parts by weight of color masterbatch are fully mixed in a mixer to obtain a mixture;

[0074] The screw extruder is heated by heat-conducting oil, and the specific segmented heating temperatures of the screw extruder are 150° C., 190° C., 210° C. and 200° C. The mixed material is transported to the screw extruder for melt blending, and 5.8 parts by weight of n-pentane foaming agent is injected into the rear end of the extruder, and then extruded through the die hole on the template, and the mixture is cut by an underwater pelletizer for cooling and granulation, separated by a centrifuge, and sieved by a vibrating screen to obtain beads with a particle size of 0.8 mm;

[0075] The beads with a particle size of 0.8 mm, 0.08 parts by weight of ethoxy lauryl amide antistatic agent and 0.4 parts by weight of zinc monostearate coating agent are mixed and stirred until fully mixed and uniform to obtain expandable polystyrene beads (expandable colored polystyrene beads, mainly used in foam packaging materials to give the product richer colors).

[0076] Example 3

[0077] The auxiliary agent composition (by weight): 1.2 parts of ultrafine talc powder (particle size is 8 μm), 2 parts of ethylene-vinyl acetate copolymer, 3 parts of low molecular weight polyethylene wax (number average molecular weight is 1000), 1.2 parts of titanium dioxide and 0.3 parts of ultraviolet absorber;

[0078] Preparation method of expandable polystyrene beads:

[0079] Use commercially available polystyrene recycled material particles;

[0080] 93 parts by weight of the polystyrene recycled material particles, 1.2 parts by weight of ultrafine talc, 2 parts by weight of ethylene-vinyl acetate copolymer, 3 parts by weight of low molecular weight polyethylene wax (number average molecular weight is 1000), 1.2 parts by weight of titanium dioxide and 0.3 parts by weight of ultraviolet absorber are fully mixed in a mixer to obtain a mixture;

[0081] The screw extruder is heated by heat-conducting oil, and the specific segmented heating temperatures of the screw extruder are 140° C., 190° C., 210° C. and 185° C. The mixed material is transported to the screw extruder for melt blending, and 5.5 parts by weight of pentane foaming agent is injected into the rear end of the extruder, and then extruded through the die hole on the template, and the mixture is rotary cut and cooled by an underwater pelletizer for granulation, separated by a centrifuge, and sieved by a vibrating screen to obtain beads with a particle size of 0.6 mm;

[0082] The beads with a particle size of 0.6 mm, 0.035 parts by weight of octadecyl dimethyl hydroxyethyl ammonium nitrate antistatic agent and 0.4 parts by weight of polyethylene glycol aqueous solution are used as surface coating agents, and are mixed and stirred until fully uniform to obtain expandable polystyrene beads (white expandable polystyrene beads, mainly used in high-end electronic product packaging and safety helmets, etc.).

[0083] Example 4

[0084] The auxiliary agent composition (by weight): 1 part of nano calcium carbonate (particle size 6 μm), 2 parts of styrene-maleic anhydride copolymer, 3 parts of low molecular weight polyethylene wax (number average molecular weight 2000), 1.2 parts of titanium dioxide and 0.3 parts of ultraviolet absorber phenyl o-hydroxybenzoate;

[0085] Preparation method of expandable polystyrene beads:

[0086] Use commercially available polystyrene recycled material particles;

[0087] 91 parts by weight of the polystyrene recycled material particles, 1 part by weight of ultrafine talc, 2 parts by weight of styrene-maleic anhydride copolymer, 3 parts by weight of low molecular weight polyethylene wax (number average molecular weight is 2000), 1.2 parts by weight of titanium dioxide and 0.3 parts by weight of ultraviolet absorber are fully mixed in a mixer to obtain a mixture;

[0088] The screw extruder is heated by heat-conducting oil, and the specific segmented heating temperatures of the screw extruder are 140° C., 190° C., 260° C. and 220° C. The mixed material is transported to the screw extruder for melt blending, and 6 parts by weight of pentane foaming agent is injected into the rear end of the extruder, and then extruded through the die hole on the template, and the mixture is cut by an underwater pelletizer for cooling and granulation, separated by a centrifuge, and sieved by a vibrating screen to obtain beads with a particle size of 0.6 mm;

[0089] The beads with a particle size of 0.6 mm, 0.06 parts by weight of octadecyl dimethyl hydroxyethyl ammonium nitrate antistatic agent and 0.4 parts by weight of polyethylene glycol aqueous solution as a surface coating agent are mixed and stirred until fully uniform to obtain expandable polystyrene beads (white expandable polystyrene beads, which have high elasticity and high compression strength and are mainly used in the field of packaging with special requirements).

[0090] Comparative Example 1

[0091] The auxiliary agent composition (by weight): 1.2 parts of ultrafine talc powder (particle size is 8um), 3 parts of low molecular weight polyethylene wax (number average molecular weight is 2000), 1.2 parts of titanium dioxide and 0.3 parts of ultraviolet absorber;

[0092] Preparation method of expandable polystyrene beads:

[0093] Use commercially available polystyrene recycled material particles;

[0094] 93 parts by weight of the polystyrene recycled material particles, 1.2 parts by weight of ultrafine talc, 3 parts by weight of low molecular weight polyethylene wax (number average molecular weight is 1000), 1.2 parts by weight of titanium dioxide and 0.3 parts by weight of ultraviolet absorber are fully mixed in a mixer to obtain a mixture;

[0095] The screw extruder is heated by heat-conducting oil, and the specific segmented heating temperatures of the screw extruder are 140° C., 190° C., 210° C. and 185° C. The mixed material is transported to the screw extruder for melt blending, and 6 parts by weight of n-pentane foaming agent is injected into the rear end of the extruder, and then extruded through the die hole on the template, and the mixture is cut by an underwater pelletizer for cooling and granulation, separated by a centrifuge, and sieved by a vibrating screen to obtain beads with a particle size of 0.6 mm;

[0096] The beads with a particle size of 0.6 mm, 0.035 parts by weight of octadecyl dimethyl hydroxyethyl ammonium nitrate antistatic agent and 0.4 parts by weight of polyethylene glycol aqueous solution as a surface coating agent were mixed and stirred until fully uniform to obtain white expandable polystyrene beads.

[0097] Test Case

[0098] Thermal conductivity is determined in accordance with GB / T 10294-2008 "Determination of steady-state thermal resistance and related properties of insulation materials - Guarded hot plate method";

[0099] The flame retardant grade assessment refers to GB 8624-2012 "Classification of Combustion Performance of Building Materials and Products";

[0100] The dimensional stability test is in accordance with GB / T 8811-2008 "Test method for dimensional stability of rigid foam plastics";

[0101] The compression strength test is in accordance with GB / T 8813-2020 "Determination of compression properties of rigid foam plastics".

[0102] The test results are shown in Table 1:

[0103] Table 1 Performance test results of the expandable polystyrene beads described in Examples 1 to 4 and the expandable polystyrene beads described in Comparative Example 1

[0104]

[0105] As can be seen from Table 1, the technical solution of the present invention improves product performance, and also solves the problem that polystyrene recycled materials cannot be foamed due to molecular chain breakage during the recycling process, thereby realizing the production process of fully recycled polystyrene materials.

[0106] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. An auxiliary agent for modified polystyrene recycled material, characterized in that: According to the weight percentage, it includes 1 to 1.5 parts of nucleating agent, 1 to 2 parts of modifier, and 0.5 to 3 parts of lubricant; The modifier includes one or more of OPS oriented polystyrene recycled material, styrene-maleic anhydride copolymer, ethylene-vinyl acetate copolymer and POE polyolefin elastomer.

2. The auxiliary agent according to claim 1, characterized in that The nucleating agent includes one or more of talc, nano calcium carbonate and graphite.

3. The auxiliary agent according to claim 1, characterized in that The lubricant includes low molecular weight polyethylene wax and / or white oil; The number average molecular weight of the low molecular weight polystyrene wax is 1000-2000.

4. The auxiliary agent according to any one of claims 1 to 3, characterized in that It also includes one or more of flame retardants, antioxidants, ultraviolet absorbers and masterbatches.

5. The auxiliary agent according to claim 4, characterized in that The flame retardant includes one or more of octabromoether, methyl octabromoether, chlorinated paraffin, brominated SBS and tetrabromobisphenol A.

6. The auxiliary agent according to claim 4, characterized in that The antioxidant includes one or more of antioxidant 1010 , antioxidant 1098 and antioxidant 1078 .

7. A method for preparing expandable polystyrene beads, characterized in that: The following steps are involved: The polystyrene recycled material particles and the additive are mixed and kneaded, and then melt-extruded and granulated in sequence to obtain beads, and a foaming agent is added during the melt-extrusion process; mixing the beads, a coating agent and an antistatic agent to obtain the expandable polystyrene beads; The auxiliary agent is the auxiliary agent according to any one of claims 1 to 5.

8. The preparation method according to claim 7, characterized in that: The mass ratio of the polystyrene recycled material particles to the additive is (91-94):(6-9).

9. The preparation method according to claim 7, characterized in that: The foaming agent includes one or more of n-pentane, isopentane and n-butane; The ratio of the mass of the foaming agent to the total mass of the polystyrene recycled material particles and the auxiliary agent is (5.5-6.5):

100.

10. The preparation method according to claim 7, characterized in that: The temperature of the melt extrusion is 140 to 260°C; The coating agent includes one or more of zinc stearate, mono- and di-stearate glyceryl, tri-stearate glyceryl and polyethylene glycol; the mass ratio of the coating agent to the polystyrene recycled material particles is (0.3-0.7): (93-100); The antistatic agent comprises one or more of ethoxy lauryl amide, octadecyl dimethyl hydroxyethyl ammonium nitrate, bis(β-hydroxyethyl) coconut amine and alkyl ether phosphate potassium salt TXP-100; the mass ratio of the antistatic agent to the polystyrene recycled material particles is (0.05-0.06): (95-100).

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