Regenerated styrene resin composition and molded body prepared from same

Abstract

Provided are: a regenerated styrene-based resin composition which has high extrudability and impact resistance even when the content of styrene-based recycled materials is high; and a molded article which is molded from the regenerated styrene-based resin composition and which has an excellent molded article appearance. A regenerated styrene-based resin composition which contains a styrene-based recycled material (A) and a styrene-based raw material (B), and which is characterized in that the ash content of the regenerated styrene-based resin composition after firing at 550 DEG C is 2.5 mass% or less, and the mass-average molecular weight (Mw) of the regenerated styrene-based resin composition is 170000 or more.

Description

[Technical Field]

[0001] The present invention relates to a recycled styrene resin composition that exhibits high extrudability and impact resistance even when the content of recycled styrene materials is high, and a molded article formed from the recycled styrene resin composition that has an excellent appearance. [Background Technology]

[0002] In recent years, with increasing awareness of environmental issues, recycled materials are being used more and more in the plastic parts of home appliances and office automation (OA) equipment. However, recycled materials may suffer from deterioration and foreign matter, leading to a decrease in physical properties. Furthermore, the types and quantities of discarded equipment vary, making it difficult to manufacture them consistently, achieve the required impact strength as plastic parts, or obtain a good appearance.

[0003] [Existing Technical Documents]

[0004] [Patent Literature]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2009-149768

[0006] [Patent Document 2] Japanese Patent Application Publication No. 2020-7424 [Summary of the Invention]

[0007] [The problem the invention aims to solve]

[0008] The purpose of this invention is to provide a recycled styrene resin composition that exhibits high extrudability and impact resistance even when the content of recycled styrene materials is high, and a molded article formed from the recycled styrene resin composition that has an excellent appearance.

[0009] [Technical solution used to solve the problem]

[0010] (1). A recycled styrene-based resin composition comprising recycled styrene material (A) and virgin styrene material (B), characterized in that,

[0011] The ash content of the above-mentioned recycled styrene-based resin composition after calcination at 550°C is less than 2.5% by mass.

[0012] The mass-average molecular weight (Mw) of the above-mentioned recycled styrene resin composition is 170,000 or more.

[0013] (2). The recycled styrene resin composition as described in (1), wherein the ash contains at least one of Si and Al.

[0014] (3) The recycled styrene resin composition as described in (1) or (2), wherein the mass ratio of the recycled styrene material (A) to the virgin styrene material (B) in the recycled styrene resin composition is 10 / 90 to 90 / 10.

[0015] (4). The recycled styrene resin composition described in any one of (1) to (3) is characterized in that the magnetic adsorption rate of the recycled styrene resin composition is 0.2% by mass or less.

[0016] (5). A molded body formed from a recycled styrene resin composition described in any one of (1) to (4).

[0017] [Invention Effects]

[0018] The recycled styrene resin composition of the present invention exhibits high extrudability and impact resistance even with a high recycled material content, and its molded articles have excellent appearance. Therefore, the molded articles of the recycled styrene resin composition of the present invention can be advantageously used in OA equipment, home appliance parts, groceries, and other applications. The higher the proportion of recycled styrene material (A) in the recycled styrene resin composition, the less styrene virgin material (B) is used, thereby reducing the environmental impact caused by the manufacture of styrene virgin material (B).

[0019] In addition, conventional recycled styrene resin compositions have experienced reduced extrudability and deteriorated appearance quality of molded products. The reason for the reduced extrudability and deteriorated appearance quality of molded products is the presence of metallic materials in the recycled styrene resin compositions. Therefore, by specifying the magnetic adsorption rate of the recycled styrene resin composition, the extrudability of the recycled styrene resin composition and the appearance of its molded products can be improved. [Detailed Implementation]

[0020] The following describes embodiments of the present invention. The features shown in the embodiments described below can be combined with each other. Furthermore, the invention is independent of each feature.

[0021] [Recycled styrene-based resin composition]

[0022] An embodiment of the present invention provides a recycled styrene-based resin composition comprising styrene-based recycled material (A) and styrene-based virgin material (B).

[0023] The ash content of the above-mentioned recycled styrene-based resin composition after calcination at 550°C is less than 2.5% by mass.

[0024] The mass-average molecular weight (Mw) of the above-mentioned recycled styrene resin composition is 170,000 or more.

[0025] In the recycled styrene-based resin composition, the mass ratio of the recycled styrene material (A) to the virgin styrene material (B) (recycled styrene material (A) / virgin styrene material (B)) can be 10 / 90 to 90 / 10, for example, 10 / 90, 20 / 80, 25 / 75, 30 / 70, 35 / 65, 40 / 60, 45 / 55, 50 / 50, 55 / 45, 60 / 40, 65 / 35, 70 / 30,

[0026] 75 / 25, 80 / 20, 90 / 10, or any two of the proportions exemplified here are possible. Within this range, a recycled styrene resin composition with high extrudability and impact resistance can be obtained, as well as a molded article with an excellent appearance formed from the recycled styrene resin composition. Furthermore, within this range, by increasing the proportion of recycled styrene material (A) in the recycled styrene resin composition, the amount of virgin styrene material (B) used can be reduced, thereby mitigating the environmental impact caused by the manufacture of virgin styrene material (B).

[0027] <Styrene-based recycled materials (A)>

[0028] In this invention, styrene-based recycled material (A) refers to recycled material containing styrene-based resin, which can be either pre-consumer or post-consumer material. Pre-consumer material refers to scraps, defective products, and materials from styrene-based resin products that were discarded before leaving the factory due to unsold products or exceeding their shelf life, generated during the recycling and reuse of these materials. Post-consumer material refers to material that was once placed on the market and is recycled and reused after consumer use. Furthermore, the amount of styrene-based recycled material (A) used refers to the total amount of styrene-based recycled material (A) used in combination.

[0029] In this invention, from the perspective of manufacturing products with low environmental impact, promoting green procurement, and improving resource reuse rates, styrene-based recycled materials are preferably post-consumer materials. Specific examples of styrene-based resins suitable as post-consumer materials include expanded polystyrene, extruded sheets, containers, packaging materials, CD / MD and other recording media cases, spools, clothes hangers and other miscellaneous goods, plastic parts of electrical equipment and OA equipment, plastic parts of home appliances such as televisions / air conditioners, or plastic parts of OA equipment such as copiers.

[0030] <Styrene-based raw materials (B)>

[0031] In this invention, styrene-based virgin material (B) refers to unused styrene-based resin that has not undergone the styrene-based resin product manufacturing process. One type of styrene-based resin described below can be used alone, or two or more types can be used simultaneously. Furthermore, when using styrene-based virgin material (B), the amount of styrene-based virgin material (B) used refers to the total amount of styrene-based virgin material (B) used.

[0032] <Styrene-based resins>

[0033] The following is a detailed explanation of styrene-based resins.

[0034] Styrene-based resins are obtained by free radical polymerization of aromatic vinyl monomers. Conjugated diene rubber-like polymers can also be added for rubber modification if necessary. Known polymerization methods can be used, such as bulk polymerization, bulk-suspension two-stage polymerization, and solution polymerization. The aromatic vinyl compound monomers are monocyclic or polycyclic aromatic vinyl monomers, such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, 3,4-dimethylstyrene, 3,5-dimethylstyrene, p-ethylstyrene, m-ethylstyrene, o-ethylstyrene, p-tert-butylstyrene, 1-vinylnaphthalene, 2-vinylnaphthalene, 1,1-diphenylethylene, isopropenylbenzene (α-methylstyrene), isopropenyltoluene, isopropenylethylbenzene, isopropenylpropylbenzene, isopropenylbutyrate, isopropenylpentylbenzene, isopropenylhexylbenzene, isopropenyloctylbenzene, etc., preferably styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, 3,4-dimethylstyrene, 3,5-dimethylstyrene, p-ethylstyrene, m-ethylstyrene, o-ethylstyrene, p-tert-butylstyrene, etc., or a mixture of two or more of them. Aromatic vinyl monomers can be used alone or in combination of two or more. Homopolymers of styrene monomers are obtained by polymerizing styrene monomers, which are aromatic vinyl monomers. Homopolymers of styrene monomers refer to polymers formed solely of styrene monomers, but can also be copolymers of two or more styrene monomers.

[0035] Examples of conjugated diene rubber-like polymers used for rubber modification of styrene-based resins include polybutadiene, random or block copolymers of styrene-butadiene, polyisoprene, polychloroprene, random, block or graft copolymers of styrene-isoprene, ethylene-propylene rubber, and ethylene-propylene-diene rubber, with polybutadiene and random, block or graft copolymers of styrene-butadiene being particularly preferred. Furthermore, these polymers may also be partially hydrogenated.

[0036] Examples of styrene-based resins include polystyrene (GPPS), rubber-modified polystyrene (HIPS), ABS resin (acrylonitrile-butadiene-styrene copolymer), AS resin (acrylonitrile-styrene copolymer), MS resin (methyl methacrylate-styrene copolymer), AAS resin (acrylonitrile-acrylic rubber-styrene copolymer), and AES resin (acrylonitrile-ethylene-propylene-styrene copolymer).

[0037] Commonly known methods for polymerizing styrene-based resins include bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization. Considering quality and productivity, bulk polymerization and solution polymerization are preferred, and continuous polymerization is even more desirable. Solvents that can be used include, for example, alkylbenzenes such as benzene, toluene, ethylbenzene, and xylene; ketones such as acetone and methyl ethyl ketone; and aliphatic hydrocarbons such as hexane and cyclohexane.

[0038] In continuous polymerization, firstly, in the polymerization step, known stirred tanks or tower reactors are used to control the polymerization reaction by adjusting the polymerization temperature to achieve the target molecular weight, molecular weight distribution, and reaction conversion rate. The polymer solution containing the polymer, after the polymerization step, is transferred to a devolatilization step to remove unreacted monomers and polymerization solvent. The devolatilization step is carried out using a vacuum devolatilization tank with a heater or a devolatilization extruder with vents. The molten polymer after the devolatilization step is transferred to a granulation step. In the granulation step, the molten resin is extruded from a porous die in a filament shape and processed into granules using cold cutting, air hot cutting, or underwater hot cutting methods.

[0039] During the polymerization of styrene-based resins, polymerization initiators and chain transfer agents can be used as needed. Free radical polymerization initiators are preferred, and commonly used examples include peroxy ketals such as 1,1-di(tert-butylperoxy)cyclohexane, 2,2-di(tert-butylperoxy)butane, 2,2-di(4,4-di-tert-butylperoxycyclohexyl)propane, and 1,1-di(tert-pentylperoxy)cyclohexane; hydrogen peroxides such as cumene hydroperoxide and tert-butyl hydroperoxide; alkyl peroxides such as tert-butyl acetate peroxide and tert-pentyl isononanoate peroxide; tert-butylisopropylphenyl peroxide; di-tert-butyl peroxide; and diisopropyl peroxide. Dialkyl peroxides such as benzene and di-tert-hexyl peroxide, peroxide esters such as tert-butyl peroxyacetate, tert-butyl peroxybenzoate, and tert-butyl peroxyisopropyl carbonate, peroxyisopropyl tert-butyl carbonate, peroxycarbonates such as polyether tetra(tert-butyl peroxycarbonate), N,N'-azobis(cyclohexane-1-carboxynitrile), N,N'-azobis(2-methylbutyronitrile), N,N'-azobis(2,4-dimethylpentanonitrile), and N,N'-azobis[2-(hydroxymethyl)propionitrile], etc., can be used in combination of one or more of them. As chain transfer agents, examples include aliphatic thiols, aromatic thiols, pentaphenylethane, α-methylstyrene dimers, and terpinene oils.

[0040] <weight-average molecular weight (Mw)>

[0041] From the viewpoint of strength and processability, the weight-average molecular weight (Mw) of the recycled styrene-based resin composition is preferably 170,000 to 700,000, more preferably 170,000 to 400,000. Specifically, it is, for example, 170,000, 180,000, 190,000, 200,000, 250,000, 300,000, 350,000, 400,000, 450,000, 500,000, 550,000, 600,000, 650,000, or any value between two of the values ​​exemplified here. Within this range, a styrene-based resin composition with high impact resistance and an excellent balance between flowability and heat resistance can be obtained. The weight-average molecular weight (Mw) of the homopolymer of the styrene monomer can be controlled by the reaction temperature, residence time, type and amount of polymerization initiator, type and amount of chain transfer agent, and type and amount of solvent used in polymerization.

[0042] The mass-average molecular weight (Mw) of the recycled styrene resin composition can be determined, for example, by gel permeation chromatography (GPC) under the following conditions.

[0043] GPC model: Alliance System 2695 (WATERS)

[0044] Column: TSKgel GMHXL (Tosoh Corporation)

[0045] Mobile phase: Tetrahydrofuran

[0046] Sample concentration: 0.2% by mass

[0047] Temperature: Column oven 40℃, detector 40℃

[0048] Detector: Differential refractometer, Alliance System 2414 (made by Waters)

[0049] The molecular weight is calculated based on the dissolution curve of monodisperse polystyrene at various dissolution times, and is expressed as the molecular weight converted from polystyrene.

[0050] <Ash Content>

[0051] The ash content of the recycled styrene-based resin composition after calcination at 550°C is 2.5% by mass or less, preferably 1.9% by mass or less. The ash is derived from recycled styrene material (A). Furthermore, the ash content of the recycled styrene-based resin composition after calcination at 550°C can be 0.001% by mass or more, preferably 0.01% by mass or more. Specifically, it can be within any two values ​​from 0.001, 0.005, 0.01, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, and 2.5% by mass. Within this range, a recycled styrene-based resin composition with excellent extrudability can be manufactured. In terms of extrudability, this specifically extends the lifespan of the screen (e.g., #60 plain weave screen (280 μm mesh)) used during the extrusion of the recycled styrene resin composition. The ash content of the recycled styrene resin composition after calcination at 550°C can be adjusted by changing the proportion of styrene-based recycled material (A) in the recycled styrene resin composition.

[0052] The ash content of the recycled styrene resin composition after calcination at 550°C can be calculated using the following formula.

[0053] Ash content (mass%) = (A / C) × 100

[0054] C: Mass of the recycled styrene-based resin composition before calcination

[0055] A: Quality of the residue (ash) after roasting

[0056] The calcination time can be adjusted according to the mass of the recycled styrene resin composition. Ash can be obtained by heating 10 to 11 g of granulated recycled styrene resin composition for 1 hour.

[0057] The roasting includes a heating-up step and a roasting step. In the heating-up step, the recycled styrene resin composition is heated to the temperature at which it becomes ash, and in the roasting step, the recycled styrene resin composition becomes ash. The heating-up step may include one or more isothermal steps. By setting one or more isothermal steps, sudden boiling of the molten recycled styrene resin composition can be prevented. The temperature of the isothermal step is, for example, from 300°C to 500°C, and can also be within the range between any two values among 300, 350, 400, 450, and 500°C. The duration of the isothermal step is, for example, from 0.5 to 5 hours, and can also be within the range between any two values among 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, and 5 hours. The isothermal step may, for example, sequentially include a step at 350°C for 3 hours, a step at 400°C for 2 hours, a step at 450°C for 1 hour, and a step at 500°C for 1 hour. The temperature of the roasting step is from 505 to 600°C, and can also be within the range between any two values among 505, 510, 520, 530, 540, 550, 560, 570, 580, 590, and 600°C. The duration of the roasting step is from 0.5 to 5 hours, and can also be within the range between any two values among 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, and 5 hours. The temperature and duration of the isothermal step, and the temperature and duration of the roasting step can be changed according to the amount of the recycled styrene resin composition and the ratio of the mass of the styrene-based recycled material (A) to the mass of the styrene-based virgin material (B) in the recycled styrene resin composition.

[0058] <Si and Al>

[0059] The ash may contain at least one or more elements of Si and Al. The styrene-based virgin material (B) does not contain metal elements such as Si and Al, so Si and Al are derived from the styrene-based recycled material (A).

[0060] The content rate of the Si element among the inorganic elements present in the ash can be from 0.1 to 9.0 mass%, preferably from 0.3 to 8.2%. Specifically, for example, it can be 0.1, 0.2, 0.3, 0.4, 0.5, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 3.0, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5,

[0061] 4.6, 4.7, 4.8, 4.9, 5.0, 6.0, 7.0, 8.0, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9.0 mass%, and can also be within the range between any two of the values exemplified herein.

[0062] The content of Al in the inorganic elements present in the ash can be from 0.05 to 2.0% by mass, preferably from 0.1 to 1.8%. Specifically, for example, it is 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, or 2.0% by mass, or it can be within any two of the values ​​exemplified here.

[0063] If the content of Si and Al elements in the ash is within the above-mentioned range, a recycled styrene resin composition with excellent extrudability can be manufactured.

[0064] The content of Si and Al in ash can be detected and analyzed using SEM-EDX. The content of each element in the ash is determined using SEM-EDX, and expressed as a percentage (%), which represents the proportion of Si and Al elements when the total amount of inorganic elements detected is set to 100%.

[0065] <Magnetic Adsorption Rate>

[0066] When the styrene-based recycled material (A) contained in the recycled styrene-based resin composition is a post-consumer material, the recycled styrene-based resin composition may sometimes contain metallic materials. The metallic materials may be strongly magnetic. The metallic materials may be iron and iron group transition metals (Co, Ni, Mn, Cr, etc.) and their alloys, compounds, and oxides. The metallic materials may have dimensions that allow them to be removed by a magnet.

[0067] In conventional recycled styrene resin compositions, although metal materials that can be removed manually by the operator have been removed, some metal materials that are difficult or impossible to remove manually remain. As a result, the metal materials remaining in the recycled styrene resin composition affect its extrudability and the appearance of its molded articles. Therefore, the amount of metal materials in the recycled styrene resin composition is preferably low. The amount of metal materials in the recycled styrene resin composition can be specified by the magnetic adsorption rate of the recycled styrene resin composition.

[0068] The magnetic adsorption rate of the recycled styrene-based resin composition can be 0.2% by mass or less, specifically 0.2%, 0.1%, 0.09%, 0.08%, 0.07%, 0.06%, 0.05%, 0.04%, 0.03%, 0.02%, 0.01%, 0.009%, 0.008%, 0.007%, 0.006%, 0.005%, 0.004%, 0.003%, 0.002%, or 0.001% by mass or less. By reducing the magnetic adsorption rate to the above values, a recycled styrene-based resin composition with excellent appearance of the molded article can be manufactured, and a molded article formed from the recycled styrene-based resin composition can be obtained.

[0069] The magnetic adsorption rate of the recycled styrene-based resin composition can be calculated using the following formula.

[0070] Magnetic adsorption rate (mass%) = (M / C) × 100

[0071] C: Mass of the recycled styrene-based resin composition before magnet recycling

[0072] M: Mass of the recycled styrene-based resin composition after recovery using a magnet

[0073] <Evaluation Methods for Impact Resistance>

[0074] The impact resistance of recycled styrene-based resin compositions is evaluated by Charpy impact strength (according to JIS K7111). The Charpy impact strength of the recycled styrene-based resin composition is preferably 8 kJ / m. 2 above.

[0075] <Other Ingredients>

[0076] In the recycled styrene-based resin composition of the present invention, other additives may be added without departing from the scope of the present invention, such as reinforcing materials, flame retardants, dyes and pigments, anti-coloring agents, lubricants, antioxidants, anti-aging agents, light stabilizers, antistatic agents, fillers, nucleating agents, compatibilizers, and other known additives, as well as colorants such as titanium dioxide and carbon black, and other modifiers. The method of adding these additives is not particularly limited and can be achieved using known methods. For example, they can be added during the raw material addition step, polymerization step, or post-treatment step in the manufacture of the recycled styrene-based resin composition; or during the step of mixing the resin composition using an extruder or molding machine.

[0077] <Method for manufacturing recycled styrene resin composition>

[0078] The mixing method for the recycled styrene-based resin composition of the present invention is not particularly limited, and known mixing techniques can be employed. For example, various raw materials (e.g., recycled styrene material (A) and virgin styrene material (B)) can be pre-mixed using mixing apparatus such as a mixer-type mixer, a V-type mixer, and a drum mixer, and the mixture can be melt-kneaded to produce a homogeneous resin composition. The melt-kneading apparatus is also not particularly limited, and examples include a Banbury mixer, a kneader, a roller, a single-screw extruder, a special single-screw extruder, and a twin-screw extruder. Furthermore, another method involves adding additives such as flame retardants from the middle section of the melt-kneading apparatus, such as an extruder.

[0079] <Molded Body>

[0080] Molded articles formed from recycled styrene-based resin compositions can be manufactured by molding the recycled styrene-based resin composition. There are no particular limitations on the molding methods for obtaining molded articles, films, sheets, and foams from the recycled styrene-based resin compositions of the present invention. Suitable molding methods can be used, such as calendering, blow molding, extrusion foaming, profile extrusion, lamination, blow molding, T-die film molding, sheet molding, vacuum forming, pneumatic molding, injection molding, RIM molding, injection foaming, and other known molding methods.

[0081] Examples of thermoforming methods include vacuum forming, pneumatic forming, or applications of these methods such as free stretch forming, plunger-ridge forming, ridge forming, die forming, direct injection forming, overhang forming, reverse stretch forming, air-expansion forming, plunger-assisted forming, plunger-assisted reverse load forming, and other conventionally known general forming methods.

[0082] [Example]

[0083] The present invention will now be described in detail with reference to embodiments and comparative examples, but the present invention is not limited thereto.

[0084] The materials used in the embodiments and comparative examples are as follows.

[0085] [Styrene-based recycled materials (A)]

[0086] (A-1) Post-consumer materials, polystyrene resin, ash content 0.3% by mass, magnetic adsorption rate 0.02% by mass

[0087] (A-2) Post-consumer materials, polystyrene resin, ash content 0.7% by mass, magnetic adsorption rate 0.3% by mass

[0088] (A-3) Post-consumer materials, polystyrene resin, ash content 4.0% by mass, magnetic adsorption rate 0.1% by mass

[0089] (A-4) Post-consumer material, polystyrene resin, ash content 4.0% by mass, magnetic adsorption rate 0.5% by mass

[0090] (A-5) Post-consumer material, polystyrene resin, ash content 6.0% by mass, magnetic adsorption rate 0.7% by mass

[0091] [Styrene-based virgin material (B)]

[0092] (B-1) HIPS (rubber-modified polystyrene resin, content of rubber-like polymer in 100% by mass of resin 9% by mass, molecular weight Mw 200,000)

[0093] (B-2) HIPS (rubber-modified polystyrene resin, content of rubber-like polymer in 100% by mass of resin 10% by mass, molecular weight Mw 160,000)

[0094] (Examples 1 - 8, Comparative Examples 1 - 3)

[0095] The respective components were extruded and molded while being melt-kneaded under the extrusion conditions of a total feed rate of 30 kg / hour and a screw rotation speed of 300 rpm using a twin-screw extruder (manufactured by Toshiba Corporation, TEM26SX) according to the blending amounts shown in Tables 1 and 2. The resin temperature at this time was 235 - 240°C. The extruded strand was cooled with water and then sent to a granulator to obtain pellets of the recycled styrene-based resin composition.

[0096] Evaluation of extrudability (screen life)

[0097] At the position before the die outlet of the extruder, a plate with a square opening of side 1 cm and a #60 plain weave mesh (mesh size 280 μm) were set. The extrusion amount (kg) when the resin pressure (the resin pressure that rises due to the gradual blockage of the mesh holes) reached 8.5 MPa during the extrusion molding was recorded. In addition, if the resin pressure did not reach 8.5 MPa after extruding 70 kg, it was recorded as >70. 40 kg or more was considered qualified, and less than 40 kg was considered unqualified.

[0098] Ash content (unit: % by mass)

[0099] 10 - 11 g of the pellets were placed in a magnetic crucible. The magnetic crucible was placed in an electric furnace (manufactured by Yamato Scientific, FP102), first held at 350°C for 3 hours, then at 400°C for 2 hours, then at 450°C for 1 hour, at 500°C for 1 hour, and finally at 550°C for 1 hour. After that, the weight of the residue, i.e., the ash, was measured.

[0100] Elemental analysis of ash (unit: % by mass)

[0101] The obtained ash was detected and analyzed using SEM-EDX (manufactured by JEOL Ltd., JSM-6510A) to determine the content rate of each element.

[0102] Magnetic adsorption rate (unit: mass%)

[0103] Scatter 900 - 1100 g of pellets on an aluminum tray, move a magnet of 12,000 Gauss, and collect the pellets magnetically adsorbed. Measure the mass of the collected pellets.

[0104] Production of molded products

[0105] After heating and drying the pellets at 80°C for 3 hours, use an injection molding machine (manufactured by Japan Steel Works, Ltd., J100E-P) to produce 10 plates under the conditions of a barrel temperature of 220°C and a mold temperature of 45°C. <{

[0106] The evaluation criteria for the appearance of the molded products are as follows.

[0107] ◎: As a result of visual observation, no unevenness was found on the surfaces of all 10 plates.

[0108] ○: As a result of visual observation, unevenness was found on the surfaces of 1 - 5 out of 10 plates.

[0109] ×: As a result of visual observation, unevenness was found on the surfaces of more than 6 out of 10 plates. ◎ and ○ are qualified, and × is unqualified.

[0110] Charpy impact strength: Use an injection molding machine to produce test pieces and measure them in accordance with JIS K7111.

[0111] [Table 1]

[0112]

[0113] [Table ]

[0114] unit Comparative Example 1 Comparative Example 2 Comparative Example 3 raw material A-1 Recyclable Materials quality% 50 100 A-2 Recyclable Materials quality% A-3 Recyclable Materials quality% A-4 Recyclable Materials quality% A-5 Recyclable Materials quality% 50 B-1 raw material quality% 50 B-2 raw material quality% 50 Composition Ash quality% 3 0.1 0.2 Si % by mass of ash 7.5 1.8 3.6 Al % by mass of ash 3 1.2 1.8 Molecular weight Mw 19 16 17 Magnetic adsorption rate quality% 0.25 0.005 0.009 characteristic Molded product appearance × ◎ ◎ Shapi kJ / m 7.5 6 6.7 Extrudability (screen life) kg 21 >70 50

[0115] As can be seen from the examples in Table 1, the molded products of the resin composition of the present invention have excellent appearance, impact resistance, and extrusion properties. On the other hand, as can be seen from the comparative examples in Table 2, for the resin compositions that do not meet the requirements of the present invention, the appearance and extrusion properties of their molded products are poor, or the impact resistance is poor.

[0116] [Industrial applicability]

[0117] Even when the content rate of recycled materials is high, the resin composition of the present invention has high extrusion properties and impact resistance, and the appearance of its molded products is excellent. Therefore, the molded body of the resin composition of the present invention can be advantageously used for applications such as OA equipment, home appliance parts, and sundries, and has industrial applicability.

Claims

1. A recycled styrene resin composition containing a styrene recycled material (A) and a styrene virgin material (B), characterized in that, an ash content after firing at 550°C of the recycled styrene resin composition is 2.5 mass% or less, a mass average molecular weight (Mw) of the recycled styrene resin composition is 170,000 or more.

2. The recycled styrenic resin composition according to claim 1, wherein, the ash contains at least one or more elements among Si and Al.

3. The recycled styrenic resin composition according to claim 1 or 2, wherein, a ratio of a mass of the styrene recycled material (A) to a mass of the styrene virgin material (B) in the recycled styrene resin composition is 10 / 90 to 90 / 10.

4. The reclaimed styrene resin composition according to any one of claims 1 to 3, characterized by, a magnetic adsorption rate of the recycled styrene resin composition is 0.2 mass% or less.

5. A molded body molded from the recycled styrene resin composition according to any one of claims 1 to 4.

Images