Recycled styrenic resin composition, and molded body of the same, and cartridge

Abstract

To provide a recycled styrenic resin composition which reduces environmental loads, suppresses lowering of mechanical strength and chemical resistance, and exhibits excellent appearance and heat-resistant creep characteristics, and a molded article using the same.SOLUTION: A recycled styrenic resin composition contains a recycled polystyrenic resin (A) containing a toluene-insoluble content (1) after osmium tetraoxide treatment, and a rubber-modified polystyrenic resin (B) containing rubbery polymer particles (b2) constituting a domain phase and a polystyrenic resin (b1) constituting a polymer matrix phase, wherein the toluene-insoluble content (1) after the osmium tetraoxide treatment exceeds 0 and is 10 mass% or less with respect to the total recycled styrenic resin composition.SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to a recycled styrenic resin composition, a molded article molded using the recycled styrenic resin composition, and a cartridge.

Background Art

[0002] Styrenic resins such as polystyrene are known as materials with low environmental impact because they are odorless and tasteless, suitable for food use, and the components generated by complete combustion are carbon dioxide and water vapor. In particular, waste styrenic resins such as inner losses generated in the production process of styrenic resin molding factories etc. are easy to recycle because their quality and composition are clear. However, waste styrenic resins recovered from the market contain a lot of various resins other than the waste styrenic resin, or metal powders, deposits or foreign matters. Therefore, it is difficult for molded products simply recycled from waste styrenic resins to maintain the same mechanical properties as molded products using new styrenic resins. For example, since members used in TV casings, partition shelves in refrigerators, or cartridges of multifunctional machines etc. contain a lot of styrenic resins, technologies for material recycling of these members are required. Patent Document 1 discloses a technique for suppressing a decrease in appearance designability by adsorbing dibutylhydroxytoluene molecules or dibutylhydroxytoluene dimers of resin additives, which are the causes of resin adhesion to molds during molding and yellowing over time, to zeolite in a recycled styrenic resin composition containing used styrenic resin and zeolite. Further, Patent Document 2 describes a technology of a recycled polystyrene-based resin containing a polystyrene resin containing a flame retardant and a rubber component and a used resin waste material (C) not containing a rubber component, a styrenic thermoplastic elastomer (D), a bromine-based flame retardant (E), and a polyfluoroolefin (F) in order to provide a polystyrene-based resin exhibiting good rigidity, impact strength, moldability, and flame retardancy equivalent to those of an unused polystyrene resin.

Prior Art Documents

Patent Documents

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2020-007424 [Patent Document 2] Japanese Patent Application Laid-Open No. 2018-087261 [Summary of the Invention] [Problems to be Solved by the Invention]

[0004] In the technologies of the above Patent Documents 1 and 2, although mechanical strength and flame retardancy have been studied, chemical resistance and appearance are insufficient. Therefore, the problem to be solved by the present disclosure is to provide a recycled styrene-based resin composition that reduces environmental impact, suppresses a decrease in mechanical strength, and exhibits excellent appearance, a molded article using the same, and a cartridge. [Means for Solving the Problems]

[0005] As a result of intensive research in view of the above problems, the present inventor has found that the content of components that cause a decrease in the physical properties of the styrene-based resin composition contained in the recycled polystyrene-based resin (A) can be quantified by osmium tetroxide treatment, and for the recycled polystyrene-based resin (A), in a composition in which virgin rubber-modified polystyrene (hereinafter also referred to as HIPS) is blended in a predetermined amount, by controlling the toluene-insoluble matter (1) after osmium tetroxide treatment derived from the recycled polystyrene-based resin (A) to a predetermined amount, a recycled styrene-based resin composition that suppresses a decrease in mechanical strength and exhibits excellent appearance, a molded article using the same, and a cartridge have been successfully realized, and the present invention has been completed. That is, the present disclosure is as follows.

[0006] [1] This disclosure relates to a recycled styrenic resin composition containing a recycled polystyrene-based resin (A) containing toluene-insoluble matter (1) after osmium tetroxide treatment, and a rubber-modified polystyrene-based resin (B) containing rubber-like polymer particles (b2) constituting a domain phase and a polystyrene-based resin (b1) constituting a polymer matrix phase, wherein the toluene-insoluble matter (1) after osmium tetroxide treatment of the recycled styrenic resin composition is more than 0 to 10% by mass based on the entire recycled styrenic resin composition. [2] This disclosure relates to a recycled polystyrene-based resin (A) containing toluene-insoluble matter (1) after osmium tetroxide treatment, as well as rubber-like polymer particles (b2) and a polystyrene-based resin (b1), wherein 55 to less than 97.9% by mass of a polymer component including the polymer matrix part (a1) of the recycled polystyrene-based resin (A) and the polystyrene-based resin (b1), 2.1 to 35% by mass of a rubber component including the rubber-like polymer particles (b2), and more than 0 to 10% by mass of toluene-insoluble matter (1) after osmium tetroxide treatment of the recycled polystyrene-based resin (A) after osmium tetroxide treatment, are included. [3] In the composition dispersion obtained by dissolving and dispersing the recycled styrenic resin composition in N,N-dimethylformamide, the dispersed substance satisfies the following formula (1): [Equation 1] 0 < (|d 84% - d 16% |) / 2 < 2 (1) (In the above formula, d 84% represents the 84% diameter of the integrated distribution curve of the particle diameter of the dispersed substance measured by the laser diffraction method, and d 16% represents the 16% diameter of the integrated distribution curve of the particle diameter of the dispersed substance measured by the laser diffraction method.) The recycled styrenic resin composition according to [1], which satisfies the above.

[0007] [4] The recycled styrenic resin composition according to any one of [1] to [3], further containing a styrenic resin (C).

[0008] [5] The recycled styrenic resin composition according to any one of [2] to [4], wherein the weight average molecular weight (Mw) of the polymer component is in the range of 100,000 to 350,000.

[0009] [6] The recycled styrenic resin composition according to any one of [1] to [5], wherein the average particle diameter of all the rubber-like polymer particles contained in the recycled styrenic resin composition is in the range of 1.6 to 3.2 μm.

[0010] [7] All the rubber-like polymer particles contained in the recycled styrenic resin composition contain a conjugated diene monomer unit, and the content of the conjugated diene monomer unit is 2 to 15% by mass based on the whole recycled styrenic resin composition. The recycled styrenic resin composition according to any one of [1] to [6].

[0011] [8] The recycled styrenic resin composition according to any one of [1] to [7], containing one or more selected from the group consisting of an antioxidant, a pigment, a flame retardant, an additive, a mineral oil, a vegetable oil, and a lubricant.

[0012] [9] The recycled styrenic resin composition according to any one of [1] to [8], wherein the content of all the rubber-like polymer particles is 2.1 to 35% by mass based on the whole recycled styrenic resin composition.

[0013]

[10] Step (I) of preparing a recycled polystyrene resin (A) containing osmium tetroxide-treated toluene-insoluble matter (1), and a rubber-modified polystyrene resin (B) containing rubber-like polymer particles (b2) constituting a domain phase and a polystyrene resin (b1) constituting a polymer matrix phase. Step (II) of melt-kneading the recycled polystyrene resin (A) and the rubber-modified polystyrene resin (B), and a method for producing a recycled styrene resin composition according to any one of [1] to [9], which produces the recycled styrene resin composition.

[0014]

[11] A molded article formed by molding the recycled styrene resin composition according to any one of [1] to [9].

[0015]

[12] A cartridge detachably attached to an image forming apparatus that forms a multi-color or single-color image on a recording medium by an electrophotographic method, having a cartridge body, a photosensitive drum, and charging means for charging the surface of the photosensitive drum, The cartridge body contains a recycled polystyrene resin (A) containing toluene-insoluble matter (1) after osmium tetroxide treatment, and a rubber-modified polystyrene resin (B) containing rubber-like polymer particles (b2) constituting a domain phase and a polystyrene resin (b1) constituting a polymer matrix phase, and the toluene-insoluble matter (1) after osmium tetroxide treatment is more than 0 to 10% by mass based on the whole recycled styrene resin composition. Cartridge.

Advantages of the Invention

[0016] According to the present disclosure, it is possible to provide a recycled styrene resin composition that suppresses a decrease in mechanical strength and chemical resistance and exhibits excellent appearance and excellent heat creep characteristics. According to the present disclosure, it is possible to provide a molded article and a cartridge using a recycled styrene resin composition that suppresses a decrease in mechanical strength and chemical resistance and exhibits excellent appearance and excellent heat creep characteristics.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present disclosure (hereinafter referred to as "the present embodiment") will be described in detail. However, the scope of the present disclosure is not limited to the following description, and various modifications can be made and implemented within the scope of the gist.

[0019] [Recycled Styrene Resin Composition] The recycled styrene resin composition of the present embodiment contains a recycled polystyrene resin (A) containing toluene-insoluble matter (1) after osmium tetroxide treatment, and a rubber-modified polystyrene resin (B) containing rubber-like polymer particles (b2) constituting a domain phase and a polystyrene resin (b1) constituting a polymer matrix phase. And the toluene-insoluble matter after subjecting the entire recycled styrene resin composition to osmium tetroxide treatment is more than 0 and up to 10% by mass based on the entire recycled styrene resin composition. Thereby, it is possible to provide a recycled styrene resin composition that suppresses a decrease in mechanical strength and exhibits excellent appearance.

[0020] Another aspect of the recycled styrene resin composition of the present disclosure contains a recycled polystyrene resin (A) containing toluene-insoluble matter (1) after osmium tetroxide treatment, and a polystyrene resin (b1) and rubber-like polymer particles (b2), the polymer component including the polymer matrix part (a1) of the recycled polystyrene resin (A) and the polystyrene resin (b1) is less than 55 to less than 97.9% by mass with respect to the entire recycled styrene resin composition, and the rubber component including the rubber-like polymer particles (b2) is 2.1 to 35% by mass with respect to the entire recycled styrene resin composition, and The recycled styrene-based resin composition contains the content of toluene-insoluble matter (1) after the osmium tetroxide treatment in an amount of more than 0% to 10% by mass based on the whole recycled styrene-based resin composition. Accordingly, it is possible to provide a recycled styrene-based resin composition that suppresses a decrease in mechanical strength and chemical resistance and exhibits excellent appearance and heat creep properties. In the present embodiment, the rubber-like polymer particles (b2) and the polystyrene-based resin (b1) may be contained in the recycled styrene-based resin composition as a rubber-modified polystyrene-based resin (B) containing the rubber-like polymer particles (b2) as a domain phase and the polystyrene-based resin (b1) as a polymer matrix phase.

[0021] The polymer component, the polymer matrix part (a1), and the polystyrene-based resin (b1) essentially contain a styrene-based monomer unit and, if necessary, contain an unsaturated carboxylic acid-based monomer unit described later. And the polymer component is a mixture containing the polymer matrix part (a1) of the recycled polystyrene-based resin (A) containing toluene-insoluble matter (1) after the osmium tetroxide treatment and the polystyrene-based resin (b1), and the polystyrene-based resin (b1) and the rubber-like polymer particles (b2) may be materials derived from the rubber-modified polystyrene-based resin (B). The unsaturated carboxylic acid-based monomer is preferably a (meth)acrylic acid monomer and a (meth)acrylic acid ester monomer. Examples of the (meth)acrylic acid monomer include acrylic acid or methacrylic acid. Examples of the (meth)acrylic acid ester monomer include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, (n-butyl) (meth)acrylate, (t-butyl) (meth)acrylate, (isobutyl) (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, (n-octyl) (meth)acrylate, (2-ethylhexyl) (meth)acrylate, decyl (meth)acrylate, stearyl (meth)acrylate, and the like. These can be used alone or in combination.

[0022] Furthermore, the recycled polystyrene-based resin (A) may contain rubber-like polymer particles (a2). That is, the recycled polystyrene-based resin (A) may include a used rubber-modified polystyrene-based resin. Therefore, when the recycled polystyrene-based resin (A) contains rubber-like polymer particles (a2), the recycled polystyrene-based resin (A) contains a polymer matrix part (a1) of the recycled polystyrene-based resin (A) and rubber-like polymer particles (a2). In addition, when the recycled polystyrene-based resin (A) contains rubber-like polymer particles (a2), the rubber component contains rubber-like polymer particles (a2) and rubber-like polymer particles (b2).

[0023] When classifying the components contained in the recycled styrene-based resin composition of this embodiment morphologically, the recycled styrene-based resin composition can be classified into a polymer component, a rubber component, toluene-insoluble matter (1) after osmium tetroxide treatment (= contaminants derived from the recycled polystyrene-based resin (A)), and optionally added components. And, as the polymer component, it includes a polymer matrix part (a1) derived from the recycled polystyrene-based resin (A), a polystyrene-based resin (b1) derived from the rubber-modified polystyrene-based resin (B), and optionally a styrene-based resin (C). As the rubber component, it includes rubber-like polymer particles (b2) derived from the rubber-modified polystyrene-based resin (B) and optionally rubber-like polymer particles (a2) derived from the recycled polystyrene-based resin (A). Further, the toluene-insoluble matter (1) after osmium tetroxide treatment contains contaminants derived from the recycled polystyrene-based resin (A) (for example, other resins (for example, olefin resins such as polyethylene-based resins and polypropylene-based resins), inorganic substances (for example, metal powder or silica), pigments, adherends or foreign matters). In another expression, the recycled styrene-based resin composition can be classified into a polymer matrix phase composed of a styrene-based polymer (for example, including the polymer matrix part (a1), the polystyrene-based resin (b1), and, if necessary, a styrene-based resin (C) not containing rubber-like polymer particles), a rubber component containing rubber-like polymer particles (b2) dispersed in the polymer matrix phase (for example, in a sea-island structure), and contaminants derived from the recycled polystyrene-based resin (A) (for example, other resins (for example, olefin resins such as polyethylene-based resins and polypropylene-based resins), inorganic substances (for example, metal powder or silica), pigments, adherends, or foreign matters). Therefore, the polymer matrix phase composed of the styrene-based polymer is referred to as the "polymer component" in this specification. And the "rubber component" is referred to as a component composed of the rubber-like polymer particles (b2) and, if necessary, the rubber-like polymer particles (a2) contained therein. In addition, the contaminants derived from the recycled polystyrene resin (A) are insoluble in toluene even after the osmium tetroxide treatment described below, and it was confirmed that the amount thereof is constant before and after the toluene dissolution treatment after the osmium tetroxide treatment. On the other hand, the polymer component is soluble in toluene. Furthermore, the rubbery polymer particles (b2) and (a2) containing conjugated diene monomer units are insoluble in toluene, but it was confirmed that they become soluble in toluene when the osmium tetroxide treatment described below is carried out. The total of the polymer phase encapsulated in the rubbery polymer particles (b2) and (a2) (for example, the polymer phase in the rubbery polymer particles having a core-shell structure or a salami structure) and the graft polymer chain (styrene-based polymer) having a styrene-based monomer on the surface of the rubbery polymer particles is referred to as the "occluded component" in this specification. For convenience, in this specification, the "polymer component" is composed of the above-mentioned styrene-based polymer and is a component soluble in toluene in the recycled styrene-based resin composition before the osmium tetroxide treatment. On the other hand, the "occluded component" is composed of the above-mentioned styrene-based polymer and is a component insoluble in toluene in the recycled styrene-based resin composition before the osmium tetroxide treatment, minus the total amount of the amount of the toluene-insoluble component after the osmium tetroxide treatment (= the toluene-insoluble component (1) after the osmium tetroxide treatment) and the amount of the rubbery polymer with respect to the component insoluble in toluene. In addition, the "toluene-insoluble component (1) after the osmium tetroxide treatment" in this specification refers to the recycled styrene-based resin composition or the recycled polystyrene resin (A) after being subjected to a toluene dissolution treatment to be separated into a component soluble in toluene and a component insoluble in toluene, then the component insoluble in toluene is subjected to an osmium tetroxide treatment to cleave carbon-carbon double bonds, and further subjected to a toluene dissolution treatment to be separated into a component soluble in toluene after the osmium tetroxide treatment and a component insoluble in toluene after the osmium tetroxide treatment. Among them, the component insoluble in toluene after the osmium tetroxide treatment is referred to as the "toluene-insoluble component (1) after the osmium tetroxide treatment". For convenience of explanation in the specification, in order to distinguish it from the toluene-insoluble component (2) before the osmium tetroxide treatment, both are numbered. When the size of the contaminants derived from the recycled polystyrene resin (A) exhibits a predetermined particle size distribution, it was found that it is difficult to become the starting point of cracking, and the relational expression of formula (1) described later was defined.

[0024] In the recycled styrene resin composition of the present embodiment, the upper limit of the content of the rubber component is 35% by mass or less, less than 35% by mass, 30% by mass or less, 29% by mass or less, 28.7% by mass or less, 28.4% by mass or less, 28.1% by mass or less, 27.8% by mass or less, 27.4% by mass or less, 26% by mass or less, 25% by mass or less, 20% by mass or less, 15% by mass or less, 12% by mass or less, 10% by mass or less, 9% by mass or less, 8% by mass or less, 7% by mass or less, 5% by mass or less, 4.9% by mass or less, 4.8% by mass or less, 4.7% by mass or less, 4.6% by mass or less, preferably with respect to the entire recycled styrene resin composition. On the other hand, the lower limit of the content of the rubber component is preferably 2.1% by mass or more, 2.7% by mass or more, 3.1% by mass or more, 3.7% by mass or more, 4% by mass or more, 6% by mass or more, 7% by mass or more, 8% by mass or more, 9% by mass or more, 9.3% by mass or more, 9.5% by mass or more, or 10% by mass or more with respect to the entire recycled styrene resin composition. The above upper limit value and the above lower limit value can be appropriately combined. When the content of the rubber component is within the above range, the effects of improving heat-resistant creep properties and chemical resistance are achieved. The content of the rubber component is calculated as the value obtained by subtracting the toluene-insoluble content (1) after osmium tetroxide treatment from the toluene-insoluble content (2) before osmium tetroxide treatment, as will be described later.

[0025] In the recycled styrene resin composition of the present embodiment, the lower limit of the content of the polymer component is 64% by mass or more, more than 64% by mass, 65% by mass or more, 70% by mass or more, 75% by mass or more, or 80% by mass or more with respect to the entire recycled styrene resin composition. On the other hand, the upper limit of the content of the polymer component is less than 97.9% by mass, 97.5% by mass or less, 97% by mass or less, 96% by mass or less, 95% by mass or less, less than 95% by mass, 94.8% by mass or less, 94% by mass or less, 93% by mass or less, 92% by mass or less, 91% by mass or less, 90% by mass or less, or less than 90% by mass with respect to the entire recycled styrene resin composition. The values of the above upper limit and the above lower limit can be combined as appropriate. In addition, the content of the polymer component is calculated by subtracting the toluene-insoluble matter (2) before the osmium tetroxide treatment from the total amount of the recycled styrene-based resin composition. Further, the polymer component may further contain a styrene-based resin (C) in addition to the polymer matrix portion (a1) and the polystyrene-based resin (b1) of the recycled polystyrene-based resin (A). In the polymer component of the present embodiment, with respect to the entire polymer component, the styrene-based monomer unit is preferably 50 to 100% by mass, the (meth)acrylic acid monomer unit is 0 to 20% by mass, and the (meth)acrylic acid ester monomer unit is 0 to 50% by mass. More preferably, the styrene-based monomer unit is 55 to 100% by mass, the (meth)acrylic acid monomer unit is 0 to 15% by mass, and the (meth)acrylic acid ester monomer unit is 0 to 45% by mass. In the present embodiment, the weight average molecular weight (Mw) of the entire polymer component is preferably 100,000 to 350,000, more preferably 100,000 to 300,000, still more preferably 110,000 to 280,000, even more preferably 115,000 to 250,000, and particularly preferably 120,000 to 230,000. When the weight average molecular weight is 100,000 to 350,000, a resin excellent in the practicality of the balance between impact strength and fluidity can be obtained. The weight average molecular weight can be measured in terms of standard polystyrene by gel permeation chromatography.

[0026] The "recycled polystyrene-based resin (A)" in the present specification contains the toluene-insoluble matter (1) after the osmium tetroxide treatment, and the content of the toluene-insoluble matter (1) after the osmium tetroxide treatment can be 10% by mass or less, preferably more than 0 to 5% by mass, still more preferably more than 0 to 3% by mass with respect to the entire recycled polystyrene-based resin (A). In another aspect, the content of the toluene-insoluble matter (1) is preferably 0.1 to 6% by mass, particularly preferably 1 to 6% by mass with respect to the entire recycled polystyrene-based resin (A). "Polystyrene resin (b1)" in this specification substantially does not contain toluene-insoluble matter (2) before osmium tetroxide treatment and toluene-insoluble matter (1) after osmium tetroxide treatment. The content of toluene-insoluble matter (1) after osmium tetroxide treatment of polystyrene resin (b1) may be less than 0.01% by mass based on the whole polystyrene resin (b1), and substantially may be below the detection limit. "Styrene resin (C)" in this specification substantially does not contain toluene-insoluble matter (2) before osmium tetroxide treatment and toluene-insoluble matter (1) after osmium tetroxide treatment. The content of toluene-insoluble matter (1) after osmium tetroxide treatment of styrene resin (C) may be less than 0.01% by mass based on the whole styrene resin (C), and substantially may be below the detection limit.

[0027] The upper limit of the content of recycled polystyrene resin (A) containing toluene-insoluble matter (1) after osmium tetroxide treatment in this embodiment is not particularly limited, but is preferably 99% by mass or less, 90% by mass or less, 80% by mass or less, 70% by mass or less, 65% by mass or less, 60% by mass or less, 50% by mass or less, 40% by mass or less with respect to the whole recycled styrene resin composition (100% by mass). When the content of the recycled polystyrene resin (A) is 70% by mass or less, more excellent impact resistance can be exhibited. On the other hand, the lower limit of the content of recycled polystyrene resin (A) containing toluene-insoluble matter (1) after osmium tetroxide treatment in this embodiment is preferably 1% by mass or more, 10% by mass or more, 20% by mass or more, 30% by mass or more, 40% by mass or more, 50% by mass or more, 60% by mass or more with respect to the whole recycled styrene resin composition (100% by mass). When the content of the recycled polystyrene resin (A) is 30% by mass or more, more excellent reduction of environmental load can be exhibited. The upper limit and the lower limit of the content of the recycled polystyrene resin (A) can be arbitrarily combined respectively.

[0028] The upper limit of the content of the rubber-modified polystyrene resin (B) in this embodiment is preferably 99% by mass or less, 90% by mass or less, 80% by mass or less, 70% by mass or less, 60% by mass or less, 50% by mass or less, 40% by mass or less with respect to the entire recycled polystyrene resin composition (100% by mass). When the content of the rubber-modified polystyrene resin (B) is 70% by mass or less, more excellent reduction of environmental load can be exhibited. On the other hand, the lower limit of the content of the rubber-modified polystyrene resin (B) in this embodiment is preferably 1% by mass or more, 10% by mass or more, 20% by mass or more, 30% by mass or more, 40% by mass or more, 50% by mass or more, 60% by mass or more with respect to the entire recycled polystyrene resin composition (100% by mass). When the content of the rubber-modified polystyrene resin (B) is 30% by mass or more, more excellent impact resistance can be exhibited. Further, the upper limit and the lower limit of the content of the rubber-modified polystyrene resin (B) can be arbitrarily combined respectively. The upper limit of the content of the rubber-like polymer particles (b2) in this embodiment is preferably 35% by mass or less, 33% by mass or less, 30% by mass or less, 28% by mass or less, 26% by mass or less, 25% by mass or less, 24% by mass or less with respect to the entire recycled polystyrene resin composition (100% by mass). The lower limit of the content of the rubber-like polymer particles (b2) in this embodiment is preferably 2.1% by mass or more, 2.5% by mass or more, 3% by mass or more, 5% by mass or more, 7% by mass or more, 9% by mass or more, 11% by mass or more with respect to the entire recycled polystyrene resin composition (100% by mass). The content of the rubber-like polymer particles (b2) is calculated as toluene-insoluble matter described later.

[0029] (Preferred form of rubber component) The average particle diameter of the rubber component in this embodiment or the average particle diameter of all the rubber-like polymer particles contained in the recycled polystyrene resin composition is preferably 1.6 to 3.2 μm, more preferably 1.7 to 2.8 μm, from the viewpoints of improving impact resistance and chemical resistance. In addition, the average particle diameter of the rubber component or all the rubber-like polymer particles contained in the recycled polystyrene resin composition can be measured by the method of the average particle diameter of the rubber-like polymer particles (b2) described later. The average particle diameter of the all-rubbery polymer particles represents the average particle diameter of the total particles of the rubbery polymer particles (b2) and the rubbery polymer particles (a2) which are optional components. When it is the average particle diameter and content of the rubbery polymer particles as described above, the balance between impact resistance and rigidity is improved well.

[0030] (Toluene-insoluble content) In the recycled styrene resin composition of the present embodiment, the "toluene-insoluble content" refers to the components undissolved in toluene after adding 1 g of an object such as the recycled styrene resin composition or recycled polystyrene resin (A) to 20 ml of toluene and shaking at 23°C for 2 hours. And the "recycled styrene resin composition or recycled polystyrene resin (A) before osmium tetroxide treatment" refers to the recycled styrene resin composition or recycled polystyrene resin (A) that has not been subjected to osmium tetroxide treatment. Therefore, the toluene-insoluble content present in the recycled styrene resin composition or the recycled polystyrene resin (A) before osmium tetroxide treatment includes rubbery polymer particles (b2) contained in the rubber-modified polystyrene resin (B), components derived from the recycled polystyrene resin (A) (rubbers other than the rubbery polymer particles (b2) (for example, rubbery polymer particles (a2)), metals, other resins (for example, olefin resins such as polyethylene resins and polypropylene resins), pigments, adherends or foreign matters), etc. On the other hand, the "recycled polystyrene resin (A) containing toluene-insoluble content (1) after osmium tetroxide treatment" refers to the recycled polystyrene resin (A) that has been subjected to osmium tetroxide treatment and contains the toluene-insoluble content remaining in the osmium tetroxide-treated recycled polystyrene resin (A) with respect to the recycled polystyrene resin (A) before osmium tetroxide treatment. And, in the recycled styrene resin composition after osmium tetroxide treatment or the recycled polystyrene resin (A) after osmium tetroxide treatment, the toluene-insoluble content contains components derived from the recycled polystyrene resin (A) (other resins (for example, olefin resins such as polyethylene resin and polypropylene resin), inorganic substances (for example, metal powder or silica), pigments, adherends or foreign matters). As shown in the reference examples described later, after treating styrene virgin materials containing unused styrene monomer units (for example, styrene resin (C) which is an unused resin and rubber-modified polystyrene resin (B), etc.) with osmium tetroxide and measuring the amount of toluene-insoluble content, it was confirmed that the virgin materials substantially did not contain toluene-insoluble content. Therefore, the content of toluene-insoluble content contained in the styrene virgin material after osmium tetroxide treatment obtained by treating the styrene virgin material with osmium tetroxide is preferably 0.01% by mass or less, more preferably 0.001% by mass or less, and even more preferably 0.0001% by mass or less, below the detection limit, based on the whole composition or styrene virgin material.

[0031] In this embodiment, the method for measuring the amount of toluene-insoluble content of the recycled styrene resin composition or the recycled polystyrene resin (A) is as follows. Weigh accurately 1 g of the recycled styrene resin composition or the recycled polystyrene resin (A) to be measured into a precipitation tube, add 20 mL of toluene, shake at 23°C for 2 hours, and then centrifuge at a temperature of 4°C, a rotation speed of 20,000 rpm, and a centrifugal acceleration of 45,100×G for 60 minutes using a centrifuge (manufactured by Sakuma Seisakusho, SS-2050A rotor: 6B-N6L). Slowly tilt the precipitation tube at about 45 degrees and remove the supernatant by decantation. Weigh accurately the mass of the insoluble content containing toluene and designate this mass as W1. Subsequently, dry it under vacuum at 160°C and 3 kPa or less for 1 hour, cool it to room temperature in a desiccator, and then weigh accurately the mass of the toluene-insoluble content and designate this mass as W2. And the toluene-insoluble content was recovered from inside the precipitation tube The swelling index of the toluene-insoluble content was determined by the following formula. Swelling index of toluene-insoluble content = (W1 / W2)

[0032] (Osmium tetroxide treatment) The osmium tetroxide treatment in this embodiment refers to a chemical treatment that utilizes an oxidation reaction with osmium tetroxide in which two hydroxy groups are syn-added to a carbon-carbon unsaturated bond such as an alkene group. Further, a catalytic amount of osmium tetroxide and an oxidizing agent are added to a compound having a carbon-carbon unsaturated bond such as an alkene group (for example, a rubber component or a toluene-insoluble component), and after converting it to a diol, a peroxide that can be added together with osmium tetroxide can cleave the carbon-carbon unsaturated bond such as an alkene group. Therefore, when the osmium tetroxide treatment is performed on the recycled styrene resin composition or the recycled polystyrene resin (A), the rubber component (conjugated diene structure) contained in the recycled styrene resin composition or the recycled polystyrene resin (A) becomes solubilized in a solvent (for example, toluene), and it has been confirmed that contaminants derived from the recycled polystyrene resin (A) contained in the recycled styrene resin composition or the recycled polystyrene resin (A) (other resins (for example, olefin resins such as polyethylene resins and polypropylene resins), inorganic substances (for example, metal powders or silica), pigments, adherends, or foreign substances) remain. From the above, in this specification, contaminants derived from the recycled polystyrene resin (A) mixed in when the recycled polystyrene resin (A) is recovered for reuse are defined as toluene-insoluble components (1) after the osmium tetroxide treatment. The osmium tetroxide treatment in this embodiment is not particularly limited as long as the rubber component (conjugated diene structure) contained in the recycled styrene resin composition or the recycled polystyrene resin (A) is solubilized in toluene, but it is preferably performed, for example, according to the following procedure. The osmium tetroxide treatment in this embodiment preferably has a step (I) of preparing an osmium tetroxide decomposing agent and a step (II) of bringing the osmium tetroxide decomposing agent into contact with the toluene-insoluble components of the recycled styrene resin composition or the recycled polystyrene resin (A). As the step (I), 30 to 500 mg of osmium(VIII) oxide (for example, 100 mg), 50 to 1,400 g (e.g., 200 g) of an aqueous solution of t-butyl hydroperoxide (concentration 40 to 80% by mass, e.g., 70% by mass), and 90 to 1,500 ml (e.g., 300 ml) of a lower alcohol (e.g., t-butyl alcohol) are preferably mixed to obtain an osmium tetroxide decomposing agent. As the step (II), after preparing a toluene-insoluble content-containing solution in which the recovered toluene-insoluble content is dissolved in an organic solvent (e.g., chloroform), an osmium tetroxide decomposing agent is added to the toluene-insoluble content-containing solution, and the osmium tetroxide decomposing agent and the toluene-insoluble content are preferably brought into contact with each other under reflux at 70 to 90 °C (e.g., in a warm water bath at 90 °C) for 10 to 30 minutes (e.g., 12 minutes). By the step (II), decomposition treatment of unsaturated bonds such as alkenes contained in the toluene-insoluble content was performed. After the step (II), a recovery step (III) for recovering the solid content and the liquid content after the decomposition treatment may be provided. As an example of the recovery step (III), after cooling the toluene-insoluble content-containing solution to which the osmium tetroxide decomposing agent is added, methanol is added to the solution while stirring, and a precipitation step (IV) for precipitating the methanol-insoluble content by the addition of methanol, and then, the methanol-insoluble content and the liquid content are separated by a glass filter, and the recovered product, which is the methanol-insoluble content, is repeatedly washed with toluene, and it is preferable to have a washing step (V) for recovering what remains on the glass filter as the toluene-insoluble content.

[0033] In the recycled styrene-based resin composition of the present embodiment, the toluene-insoluble content contained in the recycled styrene-based resin composition after the osmium tetroxide treatment is more than 0 to 10% by mass with respect to the whole recycled styrene-based resin composition, preferably 0.0001 to 5% by mass, more preferably 0.0001 to 3% by mass, still more preferably 0.0001 to 1% by mass, and particularly preferably 0.0001 to 0.5% by mass. When the toluene-insoluble content contained in the recycled styrene resin composition after osmium tetroxide treatment is in the range of more than 0 to 10% by mass, it is preferable from the viewpoint of impact resistance. In particular, when the toluene-insoluble content contained in the recycled styrene resin composition after osmium tetroxide treatment is in the range of 0.0001 to 1% by mass, it is preferable from the viewpoints of appearance and each mechanical property.

[0034] Hereinafter, each component constituting the recycled styrene resin composition of the present embodiment will be described. (Recycled polystyrene resin (A)) The recycled polystyrene resin (A) of the present embodiment is a used polystyrene resin and can be a recovered product of a so-called discarded polystyrene resin. More specifically, the recycled polystyrene resin (A) is a material (pre-consumer material) obtained by recovering and reusing scraps generated in the production process of products containing a styrene resin, defective products of products containing a styrene resin, unsold products containing a styrene resin, styrene resins that have passed the quality assurance period, and styrene resins discarded before shipment, or a material (post-consumer material) that is once shipped to the market and recovered and reused after use by consumers. And the recycled polystyrene resin (A) of the present embodiment contains a toluene-insoluble content (1) after osmium tetroxide treatment. The content of the toluene-insoluble content (1) after osmium tetroxide treatment in the recycled polystyrene resin (A) is preferably more than 0% by mass and 35% by mass or less, more preferably more than 0% by mass and 25% by mass or less, even more preferably more than 0% by mass and 20% by mass or less, still more preferably more than 0% by mass and 15% by mass or less, and particularly preferably more than 0% by mass and 10% by mass or less with respect to the whole recycled polystyrene resin (A). The recycled polystyrene resin (A) that can be used in the present disclosure is not particularly limited as long as it contains 60% by mass or more of styrene-based monomer units with respect to the whole recycled polystyrene resin (A) and the content of the toluene-insoluble content (1) after osmium tetroxide treatment is more than 0% by mass and 35% by mass or less with respect to the whole recycled polystyrene resin (A). The recycled polystyrene-based resin (A) containing toluene-insoluble matter (1) after osmium tetroxide treatment of the present disclosure may contain particles of a rubber-like polymer (a) (= rubber-like polymer particles (a2)). In addition, the recycled polystyrene-based resin (A) also includes a polystyrene-based resin recovered from used household appliances and the like. The polystyrene-based resin also includes those containing inorganic fillers such as known resins such as styrene-based elastomers, talc, mica, wollastonite, calcium carbonate, barium sulfate, magnesium carbonate, clay, alumina, silica, calcium sulfate, carbon fiber, glass fiber, metal fiber, cellulose, silica sand, gypsum, carbon black, titanium oxide, magnesium hydroxide, asbestos, zeolite, molybdenum, diatomaceous earth, sericite, shirasu, calcium hydroxide, calcium sulfite, sodium sulfate, bentonite, graphite, etc. Generally, such recycled polystyrene-based resin (A) often contains about 0.01 to 10 parts by weight of inorganic filler per 100 parts by weight of the recycled polystyrene-based resin (A). In the present embodiment, the weight average molecular weight (Mw) of the recycled polystyrene-based resin (A) before osmium tetroxide treatment is preferably 100,000 to 400,000, more preferably 120,000 to 380,000. When the weight average molecular weight is 150,000 to 350,000, a resin excellent in the practicality of the balance between impact strength and fluidity can be obtained. The weight average molecular weight can be measured by gel permeation chromatography in terms of standard polystyrene. In this embodiment, when the recycled polystyrene resin (A) before osmium tetroxide treatment contains rubbery polymer particles (a2), a resin or a polystyrene-based polymer (polystyrene and / or a polystyrene-unsaturated carboxylic acid-based polymer) containing styrene monomer units obtained from a styrene-based monomer may be encapsulated inside the rubbery polymer particles (a2), and / or a resin or a polystyrene-based polymer containing styrene monomer units may be grafted onto the surface of the rubbery polymer particles (a2). More specifically, the rubbery polymer particles (a2) in this embodiment may be any particulate material containing a rubbery polymer (a). Therefore, the form of the rubbery polymer particles (a2) includes solid particles composed of the rubbery polymer (a), hollow particles composed of the rubbery polymer (a), encapsulated particles (including microphase separation structures, core-shell structures, and salami-type structures) in which a phase containing a polystyrene-based polymer is encapsulated inside the rubbery polymer (a), and surface-grafted particles having a polystyrene-based polymer grafted onto the surface. Also, these forms may be provided in combination. The rubbery polymer (a) of this embodiment only needs to have a conjugated diene structure. Therefore, the rubbery polymer (a) is a conjugated diene-based polymer having conjugated diene monomer units, and for example, rubber components such as polybutadiene, polyisoprene, natural rubber, polychloroprene, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer can be used.

[0035] From the viewpoint of impact resistance, the average particle diameter of the rubbery polymer particles (a2) contained in the recycled polystyrene resin (A) before osmium tetroxide treatment in this embodiment is preferably 0.1 to 4.0 μm, more preferably 0.3 to 3.8 μm. Also, the average particle diameter of the rubbery polymer particles (a2) contained in the recycled polystyrene resin (A) before osmium tetroxide treatment can be measured by the method for measuring the average particle diameter of the rubbery polymer particles (b2) described later. Note that as a preferable form of the rubbery polymer particles (a2), the form of the following rubbery polymer particles (b2) can be applied.

[0036] <Integral distribution curve> In this embodiment, the dispersoid in the dispersion of the recycled styrene resin composition obtained by dissolving and dispersing the recycled styrene resin composition in N,N-dimethylformamide is represented by the following formula (1): [Equation 2] 0 < (|d 84% - d 16% |) / 2 < 2 (1) (In the above formula, d 84% represents the 84% diameter of the integrated value in the integral distribution curve of the particle diameter of the dispersoid measured by the laser diffraction method, and d 16% represents the 16% diameter of the integrated value in the integral distribution curve of the particle diameter of the dispersoid measured by the laser diffraction method.) It is preferable to satisfy this condition. Thereby, it is possible to provide a recycled styrene resin composition with reduced environmental impact and excellent mechanical strength. The dispersoid is composed of the toluene-insoluble component (1) after osmium tetroxide treatment (for example, the above-mentioned contaminants) derived from the recycled polystyrene resin (A) contained in the recycled styrene resin composition and all rubber-like polymer particles in the recycled styrene resin composition. And in the integral distribution curve obtained by integrating the particle size distribution of the dispersoid, the absolute value of the difference (hereinafter referred to as d 16% ) between the 16% diameter (d 84% ) with an integrated value of frequency (%) of 16% and the 84% diameter (d 84% - d 16% referred to as) divided by 2 is greater than 0 and less than 2. Thereby, excellent mechanical properties are exhibited. Although the details of the reason are unknown, it is considered that since many of the particles of the toluene-insoluble component derived from the recycled polystyrene resin (A) contained as the dispersoid have relatively small sizes, they are less likely to become the starting points of cracks.

[0037] The laser diffraction method is used in a particle size measuring device that utilizes the fact that the angular distribution of the forward diffraction light intensity of laser light by particles assumed to be spherical is a function of the particle size of the particles. More specifically, a monochromatic light such as laser light is projected onto a flow path of a suspension in which particles assuming the measurement object to be spherical are dispersed, and the diffracted light of the particles to be measured passing through the laser light one after another is made into a plane wave by a lens system, and the radial light intensity distribution of the plane wave is supplied to a photodetector through a rotating slit, and the detection output of the photodetector is displayed to calculate the particle size distribution of the particles. And, by the laser diffraction method, a particle size distribution on a number basis or a volume basis is obtained, in which the equivalent spherical diameter is displayed on the horizontal axis and the frequency (%) is displayed on the vertical axis. In this specification, the volume basis is adopted. Therefore, in this specification, the "particle size distribution" refers to the particle size distribution of the dispersion medium when the equivalent spherical diameter is shown on the horizontal axis and the frequency (%) (volume fraction (%)) of the dispersion medium (= osmium tetroxide-treated toluene-insoluble matter (1) derived from recycled polystyrene resin (A) and all rubber-like polymer particles in the recycled styrene resin composition) having various equivalent spherical diameters is shown on the vertical axis. In this specification, the "integral distribution curve" refers to a curve obtained by integrating the equivalent spherical diameters of the dispersion medium when the equivalent spherical diameter is shown on the horizontal axis and the integrated value of the frequency (%) is displayed on the vertical axis. Also, the integral distribution curve is a function obtained by integrating the particle size distribution. Note that the volume fraction indicates the ratio of the volume when the dispersion medium obtained at the time of measuring the particle size is regarded as a sphere. In the recycled styrene resin composition of this embodiment, for the dispersion medium, in the integral distribution curve (particle size distribution on a number basis) obtained by integrating the particle size distribution of the dispersion medium, the integrated value of the frequency (%) (hereinafter referred to as the integrated value) is 16% of the 16% diameter (d 16% ), and the absolute value of the difference from the 84% diameter (d 84% ) where the integrated value of the frequency is 84% (hereinafter referred to as d 84% -d 16% ) is more than 0 and less than 2 μm, preferably 0.1 μm or more and 1.8 μm or less, more preferably 0.2 μm or more and 1.6 μm or less, and even more preferably 0.3 μm or more and 1.5 μm or less. Further, in the integrated distribution curve (volume-based particle size distribution) obtained by integrating the particle size distribution of the dispersed phase, the integrated value of the frequency (%) (hereinafter referred to as the integrated value) at 16% is the 16% diameter (d 16% ), and the absolute value of the difference between the 84% diameter (d 84% ) at which the integrated value of the frequency is 84% (hereinafter referred to as d 84% - d 16% ), and 1 / 2 of it is greater than 0 and less than 2 μm, preferably 0.4 μm or more and 1.9 μm or less, more preferably 0.5 μm or more and 1.8 μm or less, and even more preferably 0.6 μm or more and 1.7 μm or less. d 84% - d 16% As a means for controlling the absolute value of 1 / 2 to be greater than 0 and less than 2 μm, after blending (mixing) the recycled polystyrene resin (A) and the rubber-modified polystyrene resin (B), means such as sieving with a screen mesh that passes through a screen mesh, means for crushing or pulverizing the recycled polystyrene resin (A) with a pulverizer, or means for using the recycled polystyrene resin (A) crushed or pulverized by a pulverizer can be mentioned. Examples of the pulverizer include a ball mill (for example, a rolling ball mill), a roller mill, a planetary mill, a stirring mill, and the like.

[0038] In the integrated distribution curve (number-based particle size distribution) of the dispersed phase of the present embodiment, the 84% diameter (d 84% ) at which the integrated value (on the vertical axis) is 84% is preferably 0.5 μm or more and 6.0 μm or less, more preferably 0.6 μm or more and 5.5 μm or less, and even more preferably 0.7 μm or more and 5.0 μm or less. In the integrated distribution curve (volume-based particle size distribution) of the dispersed phase of the present embodiment, the 84% diameter (d 84% ) at which the integrated value (on the vertical axis) is 84% is preferably 1.0 μm or more and 8.0 μm or less, more preferably 1.2 μm or more and 7.5 μm or less, and even more preferably 1.4 μm or more and 7.0 μm or less. In the integrated distribution curve (number-based particle size distribution) of the dispersed phase of the present embodiment, the 16% diameter (d 16%is preferably 0.05 μm or more and 4.0 μm or less, more preferably 0.1 μm or more and 3.0 μm or less, and still more preferably 0.2 μm or more and 2.0 μm or less. In the integral distribution curve (volume-based particle size distribution) of the dispersed phase of this embodiment, the integrated value (on the vertical axis) of 16% diameter (d 16% is preferably 0.1 μm or more and 4.0 μm or less, more preferably 0.2 μm or more and 3.5 μm or less, and still more preferably 0.3 μm or more and 3.0 μm or less.

[0039] <Polymer matrix part (a1)> When the recycled polystyrene resin (A) of this embodiment contains rubber-like polymer particles (a2), the recycled polystyrene resin (A) is composed of osmium tetroxide-treated toluene-insoluble matter (1), a polymer matrix part (a1), and rubber-like polymer particles (a2). On the other hand, when the recycled polystyrene resin (A) of this embodiment does not contain rubber-like polymer particles (a2), the recycled polystyrene resin (A) is composed of osmium tetroxide-treated toluene-insoluble matter (1) and a polymer matrix part (a1). The polymer matrix part (a1) of this embodiment can be a styrene copolymer resin containing a styrene-based monomer homopolymer (= polystyrene), one or more monomer units selected from the group consisting of styrene-based monomer units and unsaturated carboxylic acid-based monomer units, or a mixture of a styrene-based monomer homopolymer and a styrene copolymer resin. Examples of the monomer constituting the styrene-based monomer unit include styrene, α-methylstyrene, α-methyl-p-methylstyrene, ο-methylstyrene, m-methylstyrene, p-methylstyrene, vinyltoluene, ethylstyrene, isobutylstyrene, t-butylstyrene, and styrene derivatives such as bromostyrene and indene. As the unsaturated carboxylic acid monomer, it is preferably a (meth)acrylic acid monomer and a (meth)acrylic acid ester monomer. Examples of the (meth)acrylic acid monomer include acrylic acid or methacrylic acid. Examples of the (meth)acrylic acid ester monomer include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, (n-butyl) (meth)acrylate, (t-butyl) (meth)acrylate, (isobutyl) (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, (n-octyl) (meth)acrylate, (2-ethylhexyl) (meth)acrylate, decyl (meth)acrylate, stearyl (meth)acrylate, etc. These can be used alone or in combination. In addition, the composition of the polymer matrix part (a1) of the present embodiment varies depending on the recycled polystyrene resin (A) used, but generally, with respect to the entire polymer matrix part (a1), the styrene monomer unit is 40 to 100% by mass, the (meth)acrylic acid monomer unit is 0 to 25% by mass, and the (meth)acrylic acid ester monomer unit is preferably 0 to 50% by mass. Further, the recycled polystyrene resin (A) of the present embodiment contains toluene-insoluble matter (2) before osmium tetroxide treatment. The content of toluene-insoluble matter (2) before osmium tetroxide treatment in the recycled polystyrene resin (A) includes the above-mentioned contaminants (other resins (e.g., olefin resins such as polyethylene resins and polypropylene resins), inorganic substances (e.g., metal powders or silica), pigments, adherends or foreign matters) and, if necessary, the rubber-like polymer particles (a2) blended therein. The content of toluene-insoluble matter (2) before osmium tetroxide treatment varies depending on the recycled polystyrene resin (A) used, but generally, it is preferably more than 0 to 35% by mass, more preferably more than 0 to 30% by mass, still more preferably more than 0 to 25% by mass, even more preferably more than 0 to 20% by mass, and even more preferably more than 0 to 17% by mass with respect to the whole recycled polystyrene resin (A). In another form, the content of toluene-insoluble matter (2) before osmium tetroxide treatment is preferably 21.3% by mass or more and 35% by mass or less, and more preferably 22% by mass or more and 32% by mass or less with respect to the whole recycled polystyrene resin (A). Therefore, the content of the polymer matrix part (a1) can generally be the value obtained by removing the toluene-insoluble matter (2) before the osmium tetroxide treatment from the recycled polystyrene resin (A). In the present embodiment, the weight average molecular weight (Mw) of the polymer matrix part (a1) is preferably from 100,000 to 400,000, and more preferably from 120,000 to 380,000. When the weight average molecular weight is from 150,000 to 350,000, a resin excellent in the practicality of the balance between impact strength and fluidity can be obtained. The weight average molecular weight can be measured in terms of standard polystyrene by gel permeation chromatography.

[0040] (Rubber-modified polystyrene resin (B)) The rubber-modified polystyrene resin (B) of the present embodiment contains rubber-like polymer particles (b2) constituting the domain phase and a polystyrene resin (b1) constituting the polymer matrix phase. More specifically, the rubber-modified polystyrene resin (B) is one in which particles of a rubber-like polymer (b) (hereinafter, rubber-like polymer particles (b2)) are dispersed in a polystyrene resin (b1) as the polymer matrix phase, and can be produced by polymerizing a styrenic monomer in the presence of the rubber-like polymer (b). Examples of the polystyrene resin (b1) include polystyrene-based polymers (polystyrene and / or polystyrene-unsaturated carboxylic acid-based polymers, etc.). Also, as the rubber-modified polystyrene resin (B) of the present embodiment, a virgin material, that is, one that has not been used, is preferably used.

[0041] As the styrene monomer constituting the rubber-modified polystyrene resin (B) of the present embodiment, in addition to styrene, for example, styrene derivatives such as α-methylstyrene, α-methyl-p-methylstyrene, ο-methylstyrene, m-methylstyrene, p-methylstyrene, vinyltoluene, ethylstyrene, isobutylstyrene, and t-butylstyrene or bromostyrene and indene can be mentioned. In particular, styrene is preferred. These styrene monomers can be used alone or in combination of two or more. In the present embodiment, polystyrene is a homopolymer obtained by polymerizing the styrene monomer, and a generally available one can be appropriately selected and used.

[0042] In this embodiment, the polystyrene resin (b1) that constitutes the polymer matrix phase of the rubber-modified polystyrene-based resin (B) or the polystyrene resin (b1) contained in a part of the rubber-like polymer particles (b2) is a polymer that essentially contains a styrene-based monomer unit composed of the above styrene-based monomer. Further, the polymer may be a copolymer of the above styrene-based monomer and an unsaturated carboxylic acid-based monomer. Therefore, examples of the monomer that constitutes the polystyrene resin (b1) contained in a part of the polystyrene resin (b1) or the rubber-like polymer particles (b2) that constitute the polymer matrix phase of the rubber-modified polystyrene-based resin (B) include an unsaturated carboxylic acid-based monomer in addition to the above styrene-based monomer. As the unsaturated carboxylic acid-based monomer, a (meth)acrylic acid monomer and a (meth)acrylic acid ester monomer are preferable. Examples of the (meth)acrylic acid monomer include acrylic acid or methacrylic acid. Examples of the (meth)acrylic acid ester monomer include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, (n-butyl) (meth)acrylate, (t-butyl) (meth)acrylate, (isobutyl) (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, (n-octyl) (meth)acrylate, (2-ethylhexyl) (meth)acrylate, decyl (meth)acrylate, stearyl (meth)acrylate, and the like. These can be used alone or in combination.

[0043] The polystyrene resin (b1) that constitutes the polymer matrix phase of the rubber-modified polystyrene-based resin (B) is preferably one or more selected from the group consisting of polystyrene and a styrene-unsaturated carboxylic acid copolymer.

[0044] In this embodiment, the content of the styrene-based monomer unit with respect to the entire rubber-modified polystyrene-based resin (B) is preferably 37 to 98% by mass, and more preferably 49 to 96% by mass. In this embodiment, the content of the unsaturated carboxylic acid monomer unit with respect to the entire rubber-modified polystyrene resin (B) is preferably 0 to 63% by mass, and more preferably 0 to 51% by mass. In this embodiment, the content of the (meth)acrylic acid monomer unit with respect to the entire rubber-modified polystyrene resin (B) is preferably 0 to 3% by mass, and more preferably 0 to 1% by mass. In this embodiment, the content of the (meth)acrylate monomer unit with respect to the entire rubber-modified polystyrene resin (B) is preferably 0 to 60% by mass, and more preferably 0 to 50% by mass.

[0045] The rubber-like polymer particles (b2) contained in the rubber-modified polystyrene resin (B) of this embodiment may, for example, encapsulate a resin or a polystyrene-based polymer containing styrene monomer units obtained from the above styrene-based monomers inside the rubber-like polymer particles (b2), and / or the surface of the rubber-like polymer particles (b2) may be grafted with a resin or a polystyrene-based polymer containing styrene monomer units. More specifically, the rubber-like polymer particles (b2) in this embodiment may be any particulate material containing the rubber-like polymer (b). Therefore, the form of the rubber-like polymer particles (b2) includes solid particles composed of the rubber-like polymer (b), hollow particles composed of the rubber-like polymer (b), encapsulated particles (including microphase separation structures, core-shell structures, and salami-type structures) in which a phase containing a polymer constituting the polystyrene resin (b1) is encapsulated inside the rubber-like polymer (b), and surface-grafted particles in which a polymer constituting the polystyrene resin (b1) is grafted on the surface. Also, these forms may be provided in combination. Note that the "styrene-based monomer unit" in this specification means a repeating unit that constitutes a polymer obtained by polymerizing a styrene-based monomer, and is a repeating unit (or structural unit) in which the carbon-carbon double bond in the styrene-based monomer becomes a single bond (-C-C-) by the polymerization reaction or crosslinking reaction of the styrene-based monomer. Also, other "monomer units" in this specification have the same meaning.

[0046] As the rubber-like polymer (b) of the present embodiment, it suffices to have a conjugated diene structure. Therefore, the rubber-like polymer (b) is a conjugated diene polymer having conjugated diene monomer units. For example, rubber components such as polybutadiene, polyisoprene, natural rubber, polychloroprene, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, etc. can be used. Further, the rubber component may include a form in which a polystyrene-based resin (b1) such as polystyrene and / or a polystyrene-unsaturated carboxylic acid-based polymer is encapsulated. Among them, the rubber-like polymer (b) is preferably polybutadiene or a styrene-butadiene copolymer. For polybutadiene, both high-cis polybutadiene with a high cis content and low-cis polybutadiene with a low cis content can be used. Also, as the structure of the styrene-butadiene copolymer, both a random structure and a block structure can be used. These rubber-like polymers (b) can be used alone or in combination of two or more. Also, a saturated rubber obtained by hydrogenating a butadiene-based rubber can be used. Since the rubber-like polymer (b) constituting the rubber-like polymer particles (b2) of the present embodiment has a conjugated diene structure, the rubber-like polymer particles (b2) can be solubilized in an organic solvent such as toluene by the above osmium tetroxide treatment.

[0047] Examples of the rubber-modified polystyrene-based resin (B) of the present embodiment include HIPS (high impact polystyrene), ABS resin (acrylonitrile-butadiene-styrene copolymer), AAS resin (acrylonitrile-acrylic rubber-styrene copolymer), AES resin (acrylonitrile-ethylene propylene rubber-styrene copolymer), etc., and HIPS (high impact polystyrene) is particularly preferred. When the rubber-modified polystyrene-based resin (B) is a HIPS-based resin, among these rubber-like polymers (b), particularly preferred is high-cis polybutadiene composed of 90 mol% or more of cis 1,4 bonds. In the high-cis polybutadiene, it is preferably composed of 6 mol% or less of vinyl 1,2 bonds, and particularly preferably composed of 3 mol% or less. Incidentally, the content of the isomers having a cis-1,4 structure, a trans-1,4 structure, or a vinyl-1,2 structure among the structural units of the above high-cis polybutadiene can be calculated by measuring using an infrared spectrophotometer and performing data processing by the Morello method. In addition, the above high-cis polybutadiene can be easily obtained by polymerizing 1,3-butadiene using a known production method, for example, a catalyst containing an organoaluminum compound and a cobalt or nickel compound. In the present embodiment, when a conjugated diene polymer containing a (meth)acrylonitrile monomer unit such as an acrylonitrile monomer unit is used as the material for the rubber-like polymer particles (b2) or the rubber-like polymer (b), the content of the (meth)acrylonitrile monomer unit is preferably 10% by mass or less, more preferably 5% by mass or less, still more preferably 3% by mass or less, and particularly preferably 0.7% by mass or less with respect to the entire recycled styrene resin composition (100% by mass).

[0048] The content of the rubber-like polymer (b) contained in the rubber-modified polystyrene resin (B) of the present embodiment is preferably 2 to 15% by mass, more preferably 2.2 to 10% by mass, still more preferably 2.4 to 8% by mass with respect to 100% by mass of the total amount of the rubber-modified polystyrene resin (B). From another viewpoint, 2.6 to 6% by mass is preferable, and 3 to 5% by mass is more preferable. If the content of the rubber-like polymer (b) is less than 2% by mass, the impact resistance may decrease. Further, if the content of the rubber-like polymer (b) exceeds 15% by mass, there is a risk of a decrease in gloss and a decrease in flexural creep properties. In the present disclosure, the content of the rubber-like polymer (b) contained in the rubber-modified polystyrene resin (B) (so-called polybutadiene content) is a value calculated using thermal decomposition gas chromatography.

[0049] The content of the rubber-like polymer particles (b2) contained in the rubber-modified polystyrene resin (B) of the present embodiment (toluene-insoluble matter in the rubber-modified polystyrene resin (B)) is preferably 8 to 35% by mass with respect to 100% by mass of the total amount of the rubber-modified polystyrene resin (B). In the present disclosure, the content of the rubber-like polymer particles (b2) or all the rubber-like polymer particles contained in the rubber-modified polystyrene resin (B) or the recycled polystyrene resin composition corresponds to the toluene-insoluble content of the resin (B) or the composition before osmium tetroxide treatment. Specifically, it is calculated by the following method. To measure the content (mass%) of the rubber-like polymer particles (b2) in the composition, 1 g of the resin or composition to be measured is precisely weighed into a precipitation tube (this mass is denoted as W), 20 mL of toluene is added, and the mixture is shaken at 23°C for 2 hours. Then, it is centrifuged at 5°C or lower and 20,000 rpm (centrifugal acceleration: 4510G) for 60 minutes using a centrifuge (manufactured by Sakuma Seisakusho, SS-2050A). Then, the precipitation tube is slowly tilted to about 45 degrees, and the supernatant is removed by decantation. The obtained insoluble matter is subsequently vacuum dried at 160°C and 3 kPa or less for 1 hour, cooled to room temperature in a desiccator, and the mass of the toluene-insoluble matter is precisely weighed (this mass is denoted as G). The content (mass%) of the rubber-like polymer particles (b2) is determined by the following formula. Content of rubber-like polymer particles (b2) = (G / W) × 100

[0050] From the viewpoint of impact resistance, the average particle diameter of the rubber-like polymer particles (b2) contained in the rubber-modified polystyrene resin (B) of the present embodiment is preferably 0.5 to 3.0 μm, more preferably 0.8 to 2.8 μm. From another viewpoint, it is preferably 0.55 to 3.2 μm, and more preferably 0.65 to 2.8 μm. If the average particle diameter of the rubber-like polymer particles (b2) is less than 0.5 μm or greater than 3.0 μm, the impact strength, chemical resistance may be insufficient, or the gloss may decrease.

[0051] In the present disclosure, the average particle diameter of the rubber-like polymer particles (b2) contained in the rubber-modified polystyrene resin (B) can be measured by the following method. An ultra-thin section with a thickness of 75 nm is prepared from the rubber-modified polystyrene resin (B) stained with osmium tetroxide, and a photograph is taken at a magnification of 10,000 times using an electron microscope. In the photograph, the black-stained particles are rubber-like polymer particles (b2). From the photograph, the following mathematical formula (N1): [Equation 3] Average particle diameter = ΣniDri 3 / ΣniDri 2 (N1) (In the above mathematical formula (N1), ni is the number of rubber-like polymer (b) particles with a particle diameter of Dri, and the particle diameter Dri is the particle diameter calculated as the equivalent circle diameter from the area of the particles in the photograph.) The area average particle diameter is calculated according to the above formula, and it is used as the average particle diameter of the rubber-like polymer particles (b2). This measurement is carried out by importing the photograph into a scanner at a resolution of 200 dpi and using the particle analysis software of an image analyzer IP-1000 (manufactured by Asahi Kasei Corporation).

[0052] The reduced viscosity of the rubber-modified polystyrene resin (B) (which is an index of the molecular weight of the rubber-modified polystyrene resin (B)) is preferably in the range of 0.50 to 0.85 dL / g, and more preferably in the range of 0.55 to 0.80 dL / g. If it is less than 0.50 dL / g, the impact strength may decrease, and if it exceeds 0.85 dL / g, the moldability may decrease due to the decrease in fluidity. In the present disclosure, the reduced viscosity of the rubber-modified polystyrene resin (B) is the value measured under the conditions of 30 °C and a concentration of 0.5 g / dL in a toluene solution. In this embodiment, the weight average molecular weight (Mw) of the polystyrene resin (b1) in the rubber-modified polystyrene resin (B) is preferably 100,000 to 350,000, and more preferably 127,000 to 250,000. In another aspect, the weight average molecular weight (Mw) of the polystyrene resin (b1) can be 110,000 to 235,000, 120,000 to 224,000, or 123,000 to 193,000. When the weight average molecular weight is 100,000 to 350,000, a resin with excellent practicality in the balance between impact strength and fluidity can be obtained. The weight average molecular weight can be measured by gel permeation chromatography in terms of standard polystyrene.

[0053] The production method of the rubber-modified polystyrene resin (B) of the present embodiment is not particularly limited. However, in the presence of the rubber-like polymer (b), bulk polymerization (or solution polymerization) of the styrene monomer and optionally added unsaturated carboxylic acid monomer (and solvent), or bulk-suspension polymerization that shifts to suspension polymerization during the reaction, or emulsion graft polymerization of the styrene monomer and optionally added unsaturated carboxylic acid monomer in the presence of the rubber-like polymer (b) latex can be used for production. In bulk polymerization, a mixed solution obtained by adding the rubber-like polymer (b), the styrene monomer, the optionally added unsaturated carboxylic acid monomer, and optionally an organic solvent, an organic peroxide, and / or a chain transfer agent can be continuously supplied to a polymerization apparatus configured by connecting a completely mixed reactor or a tank reactor and a plurality of tank reactors in series for production.

[0054] In the present embodiment, the melt flow rate of the rubber-modified polystyrene resin (B) at 200°C is preferably 0.3 to 10.0 g / 10 min, more preferably 0.5 to 8.0 g / 10 min, and still more preferably 0.7 to 7.0 g / 10 min. If the melt flow rate is in the range of 0.3 to 10.0 g / 10 min, the miscibility with the recycled polystyrene resin (A) is good and the mechanical strength is also good. In the present disclosure, the melt flow rate is a value measured at 200°C and a load of 49 N in accordance with ISO 1133. The above are the essential components of the recycled styrene resin composition of the present embodiment. Hereinafter, the styrene resin (C) and optional additive components, which are optional components of the recycled styrene resin composition of the present embodiment, will be described.

[0055] (Styrene resin (C)) The recycled styrene resin composition of the present embodiment may further contain a styrene resin (C) in addition to the recycled polystyrene resin (A) and the rubber-modified polystyrene resin (B). The styrenic resin (C) of this embodiment essentially contains styrenic monomer units, and may contain monomer units derived from an unsaturated carboxylic acid monomer copolymerizable with the styrenic monomer, if necessary. Examples of the styrenic monomer are the same as those of the rubber-modified polystyrene resin (B) described above, and thus are omitted here. Examples of the unsaturated carboxylic acid monomer are the same as those of the rubber-modified polystyrene resin (B) described above, and thus are omitted here. The rubber-modified polystyrene resin (B) of this embodiment and the styrenic resin (C) are different in that the styrenic resin (C) does not contain rubber-like polymer particles (b2). In other words, the styrenic resin (C) (before osmium tetroxide treatment) substantially does not contain toluene-insoluble components. Further, the styrenic resin (C) may have the same or different polymer composition from the polystyrene resin (b1). When the styrenic resin (C) has the same polymer composition as the polystyrene resin (b1), it is difficult to distinguish between the two in the recycled styrenic resin composition. However, by controlling the composition ratio of the styrenic monomer units as the whole polymer components (components other than the rubber component) in the recycled styrenic resin composition and, if necessary, the unsaturated carboxylic acid monomer units contained, effects such as reduction of environmental load and mechanical strength can be achieved.

[0056] [Optional additive components] In this embodiment, at any stage before or after the recovery step in the production of the recycled polystyrene resin (A), the rubber-modified polystyrene resin (B) or optional components, or at the stage of extrusion processing or molding processing of the recycled styrenic resin composition, various additives may be added within a range not impairing the object of the present invention, if necessary. Examples of the additives include plasticizers such as liquid paraffin, ultraviolet absorbers, light stabilizers, antioxidants such as hindered phenol-based, phosphorus-based, and sulfur-based antioxidants, lubricants, antistatic agents, flame retardants, various dyes and pigments, inorganic crystal nucleating agents (metal oxides such as titanium oxide and tin oxide), organic crystal nucleating agents, fluorescent brighteners, light diffusing agents, and selective wavelength absorbers. The recycled styrene resin composition according to this embodiment preferably contains one or more selected from the group consisting of an antioxidant, a pigment, a flame retardant, an additive, a mineral oil, a vegetable oil, and a lubricant.

[0057] The light stabilizer of this embodiment preferably has a function of capturing and detoxifying the photo radicals generated by the recycled styrene resin composition absorbing ultraviolet rays, thereby preventing the deterioration and coloring of the composition caused by radicals, although it itself has no ultraviolet absorption ability. The light stabilizer can be used alone or in combination of two or more, and by using it in combination with the ultraviolet absorber and / or antioxidant described below, a higher light resistance effect can be exerted. Examples of the light stabilizer of this embodiment include bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, bis(1-undecanoxy-2,2,6,6-tetramethylpiperidin-4-yl) carbonate, tetrakis(2,2,6,6-tetramethyl-4-piperidyl) butane-1,2,3,4-tetracarboxylate, bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, N,N'-bis(2,2,6,6-tetramethylpiperidin-4-yl) hexane-1,6-diamine, bis(1,2,2,6,6-pentamethyl-4-piperidyl) butyl(3,5-di-t-butyl-4-hydroxybenzyl) malonate, etc. Specific product names include Adeka Stab LA-52, Adeka Stab LA-57, Adeka Stab LA-63P, Adeka Stab LA-68, Adeka Stab LA-72, Adeka Stab LA-77Y, Adeka Stab LA-77G, Adeka Stab LA-81 manufactured by ADEKA Corporation, JF-90G, JF-95 manufactured by Johoku Chemical Co., Ltd., Chimassorb 2020FDL, Chimassorb 944FDL, Tinuvin 622SF manufactured by BASF Japan Ltd., etc.

[0058] The ultraviolet absorber of this embodiment has a function of absorbing the ultraviolet rays absorbed by the recycled styrene resin composition, converting them into heat and chemical energy, thereby suppressing the generation of photo radicals due to the ultraviolet absorption of the styrene resin composition, and suppressing the deterioration and coloring of the resin. Preferred ultraviolet absorbers in this embodiment include, for example, benzotriazole compounds, triazine compounds, benzophenone compounds, and benzoate compounds. Preferred antioxidants in this embodiment include, for example, octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 4,6-bis(octylthiomethyl)-o-cresol (such as Irganox 1076 manufactured by BASF Japan Ltd.) and other hindered phenol antioxidants, tris(2,4-di-tert-butylphenyl) phosphite (such as Irgafos 168 manufactured by BASF Japan Ltd.) and other phosphorus-based processing heat stabilizers. These stabilizers may be used alone or in combination of two or more as appropriate. There is no particular limitation on the addition timing, and it may be either in the polymerization step or the devolatilization step. Also, the stabilizer can be mixed into the product using mechanical devices such as an extruder or a mixer.

[0059] The content of each of the light stabilizer, ultraviolet absorber, and antioxidant in this embodiment is 0.001 to 2.0% by mass based on the total amount of the recycled styrene resin composition. The upper limit is preferably 1.8% by mass or less, 1.6% by mass or less, 1.4% by mass or less, 1.2% by mass or less, 1.0% by mass or less, 0.8% by mass or less, 0.7% by mass or less in this order, and the lower limit is preferably 0.005% by mass or more, 0.010% by mass or more, 0.021% by mass or more, 0.051% by mass or more, 0.061% by mass or more, 0.071% by mass or more, 0.079% by mass or more, 0.089% by mass or more, 0.12% by mass or more, 0.17% by mass or more in this order. The content can be selected from any combination of the above upper and lower limits.

[0060] The recycled styrene resin composition according to the present invention may further contain a metal or a metal oxide as an inorganic crystal nucleating agent. In the recycled styrene resin composition of the present embodiment, the content of the metal oxide (for example, titanium dioxide) is preferably 0.07% by mass or more and 5.5% by mass or less, more preferably 0.65% by mass or more and 3.8% by mass or less, and still more preferably 1.2% by mass or more and 3% by mass or less, based on 100% by mass of the total amount of the recycled styrene resin composition. In another aspect, it is preferably 1.1% by mass or more and 2.8% by mass or less. In still another aspect, it is more preferably 0.2% by mass or more and 0.9% by mass or less.

[0061] In addition, each of the above various additives in the recycled styrene resin composition of the present embodiment is preferably 10.0% by mass or less, more preferably 5.5% by mass or less, still more preferably 2.9% by mass or less, even more preferably 1.5% by mass or less, and particularly preferably 0.9% by mass or less, based on 100% by mass of the recycled styrene resin composition.

[0062] [Physical properties of the recycled styrene resin composition] The preferred physical properties of the recycled styrene resin composition in the present embodiment are described below. <Vicat softening temperature> In the present embodiment, the Vicat softening temperature of the recycled styrene resin composition is preferably 88°C or higher, more preferably 91°C or higher, and even more preferably 93°C or higher. By setting the Vicat softening temperature to 88°C or higher, a molded product having excellent heat resistance can be obtained. The Vicat softening temperature in this specification is measured under the conditions of a 5 kg load and a heating rate of 50°C / h in accordance with ISO 306.

[0063] <Charpy impact strength> The Charpy impact strength of the recycled styrene resin composition of the present embodiment is preferably 5 kJ / m 2 or more, more preferably 7 to 20 kJ / m 2 It is. 5 kJ / m 2If it is less than that, there is a concern of breakage during use. In the present disclosure, the Charpy impact strength is a value measured in accordance with ISO 179.

[0064] The recycled styrene resin composition of the present embodiment preferably has a melt mass flow rate of 1.5 g / 10 min or more, more preferably 2 to 18 g / 10 min. If the melt mass flow rate is 1.5 g / 10 min or more, the moldability during extrusion molding or vacuum molding is good. The above melt mass flow rate can be achieved by adjusting the melt mass flow rates of the respective components (A) to (C) and the mixing ratio of these resins. In the present disclosure, the melt mass flow rate is a value measured at a temperature of 200 °C and 5.00 kg in accordance with ISO 1133.

[0065] In the present embodiment, the weight average molecular weight (Mw) of the recycled styrene resin composition before osmium tetroxide treatment is the same as that of the above polymer component, preferably 100,000 to 350,000, more preferably 100,000 to 300,000, still more preferably 110,000 to 280,000, even more preferably 115,000 to 250,000, and particularly preferably 120,000 to 230,000. When the weight average molecular weight is 100,000 to 350,000, a resin excellent in the practicality of the balance between impact strength and fluidity can be obtained. The weight average molecular weight can be measured by gel permeation chromatography in terms of standard polystyrene.

[0066] [Method for producing recycled styrene resin composition] In the present embodiment, the method for producing a recycled styrene resin composition includes preparing a recycled polystyrene resin (A), a rubber-modified polystyrene resin (B), and, if necessary, optional components. And the method of blending, melting, kneading, and granulating the recycled polystyrene resin (A), the rubber-modified polystyrene resin (B), and, if necessary, optional components is not particularly limited, and a method commonly used in the production of general styrene resins can be used. For example, after blending (mixing) the above components using a drum tumbler, Henschel mixer, etc., melt and knead them using a Banbury mixer, single-screw extruder, twin-screw extruder, kneader, etc., and perform a step of sieving through a screen with a mesh that passes through a screen mesh, and granulate using a rotary cutter, fan cutter, etc. to obtain a recycled styrene-based resin composition. The resin temperature in melting and kneading is preferably 180 to 240 °C. In order to achieve the target resin temperature, the cylinder temperature of the extruder, etc. is preferably set at a temperature 10 to 20 °C lower than the resin temperature. If the resin temperature is less than 180 °C, the mixing will be insufficient, which is not preferable. On the other hand, if the resin temperature exceeds 240 °C, thermal decomposition of the resin will occur, which is not preferable.

[0067] (Preferred embodiment of the method for producing a recycled styrene-based resin composition) A preferred production method of the present embodiment includes a step (I) of preparing a recycled polystyrene-based resin (A) containing toluene-insoluble matter (1) after osmium tetroxide treatment and a rubber-modified polystyrene-based resin (B) containing rubber-like polymer particles (b2) constituting a domain phase and a polystyrene-based resin (b1) constituting a polymer matrix phase. Preferably, it has a step (II) of melt-kneading the recycled polystyrene-based resin (A) and the rubber-modified polystyrene-based resin (B). Thereby, a recycled styrene-based resin composition with reduced environmental load, suppressed decrease in mechanical strength, and excellent appearance can be easily produced. Hereinafter, the above step (I) and the above step (II) will be described in detail.

[0068] <Step (I)> Step (I) is a preparation step of preparing a recycled polystyrene-based resin (A) and a rubber-modified polystyrene-based resin (B), which are raw materials of the recycled styrene-based resin composition of the present disclosure. Therefore, as the preparation step, it is preferable to have a step (I-A) of preparing a recycled polystyrene-based resin (A) and a step (I-B) of preparing a rubber-modified polystyrene-based resin (B). Thereby, depending on the compounds and properties contained in the recycled polystyrene-based resin (A) and / or the rubber-modified polystyrene-based resin (B), they are used in the step (II) described below. In addition, when using a styrene-based resin (C) that does not contain the above-mentioned rubber-like polymer particles as a raw material of the recycled styrene-based resin composition, the preparation step may further include a step (I-C) of preparing a styrene-based resin (C) that does not contain rubber-like polymer particles.

[0069] <<Step (I-A)>> As described above, the recycled polystyrene-based resin (A) of the present embodiment contains the toluene-insoluble matter (1) after osmium tetroxide treatment and the polymer matrix part (a1) of the recycled polystyrene-based resin (A). And the recycled polystyrene-based resin (A) may contain rubber-like polymer particles (a2). Therefore, as the modes of the recycled polystyrene-based resin (A), the following modes (i) and (ii) can be mentioned. (i) The recycled polystyrene-based resin (A) contains a polymer matrix part (a1) and toluene-insoluble matter (1) after osmium tetroxide treatment, and 99% by mass or more of the total amount of the recycled polystyrene-based resin (A) is occupied by the polymer matrix part (a1) and toluene-insoluble matter (1) after osmium tetroxide treatment (for example, polystyrene containing toluene-insoluble matter (1) after osmium tetroxide treatment, styrene-based copolymer resin containing toluene-insoluble matter (1) after osmium tetroxide treatment) (ii) The recycled polystyrene resin (A) contains a polymer matrix part (a1), rubber-like polymer particles (a2), and an osmium tetroxide-treated toluene-insoluble component (1), and 99% by mass or more of the total amount of the recycled polystyrene resin (A) is occupied by the polymer matrix part (a1), rubber-like polymer particles (a2), and the osmium tetroxide-treated toluene-insoluble component (1) (for example, a rubber-modified polystyrene resin containing the osmium tetroxide-treated toluene-insoluble component (1)) When the recycled polystyrene resin (A) is in the above-mentioned aspect (i), the step (I-A) is preferably a step (D1) of specifying the content of the osmium tetroxide-treated toluene-insoluble component (1) contained in the recycled polystyrene resin (A) and the weight average molecular weight of the polymer matrix part (a1). On the other hand, when the recycled polystyrene resin (A) is in the above-mentioned aspect (ii), the step (I-A) is preferably a step (D2) of specifying the content of the rubber-like polymer particles (a2) and the content of the osmium tetroxide-treated toluene-insoluble component (1) contained in the recycled polystyrene resin (A), and the weight average molecular weight of the polymer matrix part (a1). Thereby, a recycled styrene-based resin composition with reduced environmental load, more suppressed reduction in mechanical strength, and excellent appearance and excellent heat creep properties can be obtained. At this time, the content of the rubber-like polymer particles (a2), the content of the osmium tetroxide-treated toluene-insoluble component (1), and the weight average molecular weight of the polymer matrix part (a1) contained in the recycled polystyrene resin (A) are preferably within the above-mentioned ranges respectively.

[0070] <Step (I-B)> As the step (I-B) of preparing the rubber-modified polystyrene resin (B) of the present embodiment, it preferably has a step (E1) of selecting the content of the rubber-like polymer particles (b2) and the weight average molecular weight of the polystyrene resin (b1) contained in the rubber-modified polystyrene resin (B). As a result, a recycled styrene-based resin composition is obtained that reduces the environmental impact, further suppresses a decrease in mechanical strength, and exhibits a more excellent appearance and excellent heat creep properties. At this time, the content of the rubber-like polymer particles (b2) and the weight average molecular weight of the polystyrene-based resin (b1) contained in the rubber-modified polystyrene-based resin (B) are preferably within the above-described ranges, respectively.

[0071] <Step (I-C)> The step (I-C) of preparing the styrene-based resin (C) that does not contain the rubber-like polymer particles of the present embodiment preferably includes a step (E2) of selecting the weight average molecular weight of the styrene-based resin (C) that does not contain the rubber-like polymer particles. As a result, a recycled styrene-based resin composition is obtained that reduces the environmental impact, further suppresses a decrease in mechanical strength, and exhibits a more excellent appearance and excellent heat creep properties. At this time, the weight average molecular weight of the styrene-based resin (C) is preferably within the above-described range.

[0072] A preferred step (I) of the present embodiment includes a step (D2) of specifying the content of the rubber-like polymer particles (a2) and the content of the toluene-insoluble matter (1) after osmium tetroxide treatment, and the weight average molecular weight of the polymer matrix part (a1) contained in the recycled polystyrene-based resin (A), a step (E1) of selecting the content of the rubber-like polymer particles (b2) and the weight average molecular weight of the polystyrene-based resin (b1) contained in the rubber-modified polystyrene-based resin (B), and a step (E2) of selecting the weight average molecular weight of the styrene-based resin (C) that does not contain the rubber-like polymer particles. As a result, a recycled styrene-based resin composition is obtained that reduces the environmental impact, further suppresses a decrease in mechanical strength, and exhibits a more excellent appearance and excellent heat creep properties. Further, the step (I) preferably includes a step (III) of removing particulate matter having a size equal to or larger than a predetermined size (for example, a maximum average particle diameter of 200 μm or more).

[0073] <Step (II)> Step (II) is a step of melt-kneading the recycled polystyrene-based resin (A) and the rubber-modified polystyrene-based resin (B) prepared in step (I) using the recycled polystyrene-based resin (A) and the rubber-modified polystyrene-based resin (B). As the conditions for the melt-kneading, for example, it is preferable to melt-knead the respective components blended (mixed) with a drum tumbler, a Henschel mixer, etc. using a Banbury mixer, a single-screw extruder, a twin-screw extruder, a kneader, etc. Further, the resin temperature in the melt-kneading is preferably 180 to 240°C. Here, the term "melt" usually means a state in which a part of the recycled polystyrene-based resin (A) or the rubber-modified polystyrene-based resin (B) is melted, and does not mean that all the components in the system are melted. It is preferable that step (II) of the present embodiment has a step of determining the blending amounts of the recycled polystyrene-based resin (A), the rubber-modified polystyrene-based resin (B), and the styrene-based resin (C) containing no rubber-like polymer particles, which is blended as necessary. Specifically, it is preferable to determine the blending amounts so that the obtained recycled styrene-based resin composition satisfies the following (v) to (z). (v) Control the content of the polymer component including the polymer matrix part (a1) of the recycled polystyrene-based resin (A), the polystyrene-based resin (b1) of the rubber-modified polystyrene-based resin (B), and the styrene-based resin (C) containing no rubber-like polymer particles within the range of 64 to less than 90% by mass with respect to the total amount of the obtained recycled styrene-based resin composition. (x) Control the content of the rubber component including the rubber-like polymer particles (a2) and the rubber-like polymer particles (b2) within the range of 9 to less than 30% by mass, preferably 10 to less than 28% by mass with respect to the total amount of the obtained recycled styrene-based resin composition. (y) Control the content of the toluene-insoluble matter (1) after the osmium tetroxide treatment within the range of 0.1 to 6% by mass, preferably 1 to 6% by mass with respect to the total amount of the obtained recycled styrene-based resin composition. (z) Control the weight average molecular weight (Mw) of the entire polymer component within the range of 100,000 to 350,000. Thereby, a recycled styrene-based resin composition that reduces the environmental load, further suppresses the decrease in mechanical strength, and exhibits more excellent appearance and excellent heat creep properties can be obtained.

[0074] In step (II) of this embodiment, it is preferable to have a step (G) of adjusting the melt kneading conditions so that the particle size distribution (μm) of the DMF-insoluble matter in the recycled styrene-based resin composition (= the dispersed substance in the composition dispersion obtained by dissolving and dispersing the recycled styrene-based resin composition in N,N-dimethylformamide) satisfies the following formula. 0.00 < (|d84% - d16%|) / 2 < 2.00 (d84% represents the integrated value 84% diameter in the integrated distribution curve of the particle size, and d16% represents the integrated value 16% diameter in the integrated distribution curve of the particle size.) Thereby, a recycled styrene-based resin composition that reduces the environmental load, further suppresses the decrease in mechanical strength, and exhibits more excellent appearance and excellent heat creep properties can be obtained. Moreover, it is preferable that step (II) has a step (III) of removing particulate matter having a predetermined size or more.

[0075] <Step (III)> The above step (III) is a step of removing contaminants contained in the recycled polystyrene-based resin (A), and it is preferably carried out during step (I) or step (II), or after step (I) or after step (II). Thereby, a recycled styrene-based resin composition that reduces the environmental load, further suppresses the decrease in mechanical strength, and exhibits more excellent appearance and excellent heat creep properties can be obtained. For example, the above step (III) is a step of blending recycled polystyrene resin (A), rubber-modified polystyrene resin (B), and styrene resin (C) that does not contain rubber-like polymer particles if necessary, and then preferably after blending the raw materials and while the raw materials are melted, separating particulate matter having a size less than a predetermined size. In other words, it may be a step of removing toluene-insoluble matter (1) after osmium tetroxide treatment of a predetermined amount or more. Similarly, for example, after the above step (D1) or the above step (D2) and before the above step (II), a step (III) of separating particulate matter having a size less than a predetermined size may be performed. Specifically, the above step (III) includes a step of sieving with one or more sieves selected from the group consisting of a filter and a screen mesh. For example, it may be a step in which the melted raw material passes through a filter and / or a screen mesh. Thereby, the inclusion of contaminants having a size greater than a predetermined size in the recycled polystyrene resin (A) can be reduced. Further, the melting of the raw materials can be carried out, for example, by charging them into an extruder. And the passage through the filter and the screen mesh can be carried out by providing a polymer filter and / or a screen mesh near the outlet or the inlet of the extruder.

[0076] The above filter filters the polymer components of the melted raw materials, etc. Specifically, a leaf disk filter, a candle filter, or a pack filter may be mentioned. And the lower limit of the average pore diameter of the filter is preferably 10 μm or more, more preferably 30 μm or more. Also, the upper limit of the average pore diameter of the filter is preferably 200 μm or less, more preferably 180 μm or less. The above-mentioned screen mesh includes a copper mesh, a SUS (stainless steel) mesh, etc. The lower limit of the mesh opening of the screen mesh is preferably 94 μm or more, more preferably 112 μm or more, still more preferably 134 μm or more, and even more preferably 140 μm or more. Also, the mesh opening of the screen mesh is preferably 198 μm or less, more preferably 164 μm or less, still more preferably 132 μm or less, and even more preferably 109 μm or less. The above upper limit value and the above lower limit value can be arbitrarily combined. For example, the screen mesh includes 80 mesh (about 198 μm - 140 μm), 100 mesh (about 164 μm - 134 μm), 120 mesh (132 μm - 112 μm), or 150 mesh (109 μm - 94 μm). By setting the lower limit of the average pore diameter of the above filter or the mesh opening of the screen mesh to the above values, excessive resin pressure is not generated, and thus productivity tends to improve. Similarly, by setting the above values of the average pore diameter of the above filter or the mesh opening of the screen mesh, finer contaminants can tend to be removed. In this embodiment, the passage of the filter and / or the screen mesh may pass only through one of them, or may pass through both. Furthermore, the filter alone may be passed through multiple times, or the screen mesh alone may be passed through multiple times. Furthermore, these may be combined and passed through.

[0077] In this embodiment, by using the above manufacturing method, the obtained recycled styrene-based resin composition tends to have the following characteristics. The particle size distribution (μm) of the DMF-insoluble matter (= the dispersed substance in the composition dispersion obtained by dissolving and dispersing the recycled styrene-based resin composition in N,N-dimethylformamide) in the recycled styrene-based resin composition satisfies the following formula. 0.00 < (|d84% - d16%|) / 2 < 2.00 (d84% represents the integrated value 84% diameter in the integrated particle size distribution curve, and d16% represents the integrated value 16% diameter in the integrated particle size distribution curve.)

[0078] (Particularly preferred method for producing a recycled styrene-based resin composition) The method for producing a recycled styrene-based resin composition of the present embodiment is a recycled polystyrene-based resin (A) containing a polymer matrix part (a1), rubber-like polymer particles (a2), and toluene-insoluble matter (1) after osmium tetroxide treatment, a rubber-modified polystyrene-based resin (B) containing a polymer matrix phase composed of a polystyrene-based resin (b1) and a domain phase composed of rubber-like polymer particles (b2), a styrene-based resin (C) used as an optional component, and is a production method for obtaining a recycled styrene-based resin composition by melt-kneading, a step (D2) of specifying the total amount of the rubber-like polymer particles (a2) and the toluene-insoluble matter (1) after osmium tetroxide treatment contained in the recycled polystyrene-based resin (A), and the weight-average molecular weight of the polymer matrix part (a1); a step (E) of selecting the content of the rubber-like polymer particles (b2) in the rubber-modified polystyrene-based resin (B), the weight-average molecular weight of the polystyrene-based resin (b1), and the weight-average molecular weight of the styrene-based resin (C), and has, a step (F) of determining the blending amounts of the respective components of the recycled polystyrene-based resin (A), the rubber-modified polystyrene-based resin (B), and the styrene-based resin (C) so that the recycled styrene-based resin composition satisfies the following (v) to (z), and is a production method including (v) Control the content of the polymer component including the polymer matrix part (a1) of the recycled polystyrene-based resin (A), the polystyrene-based resin (b1) of the rubber-modified polystyrene-based resin (B), and the styrene-based resin (C) not containing rubber-like polymer particles to a range of 64 to less than 90% by mass based on the total amount of the obtained recycled styrene-based resin composition. (x) Control the content of the rubber component containing the rubber-like polymer particles (a2) and the rubber-like polymer particles (b2) in the range of more than 9% to less than 30% by mass based on the total amount of the resulting recycled styrene-based resin composition. (y) Control the content of the toluene-insoluble matter (1) after the osmium tetroxide treatment in the range of 1% to 6% by mass based on the total amount of the resulting recycled styrene-based resin composition. (z) Control the weight average molecular weight (Mw) of the entire polymer component in the range of 100,000 to 350,000. When melt-kneading with the determined compounding amounts, adjust the melt-kneading conditions so that the particle size distribution (μm) of the DMF-insoluble matter (= the dispersed substance in the composition dispersion obtained by dissolving and dispersing the recycled styrene-based resin composition in N,N-dimethylformamide) in the recycled styrene-based resin composition satisfies the following formula (1) (step (G)). A method for producing a recycled styrene-based resin composition having this. [Equation 4] 0.00 < (|d84% - d16%|) / 2 < 2.00 (1) (d84% represents the integrated value 84% diameter in the particle size integrated distribution curve, and d16% represents the integrated value 16% diameter in the particle size integrated distribution curve.) Moreover, it is preferable to contain the recycled polystyrene-based resin (A) in the range of 30% to 65% by mass based on the total amount (100% by mass) of the recycled styrene-based resin composition. Thereby, a recycled styrene-based resin composition that reduces the environmental load, further suppresses a decrease in mechanical strength, and exhibits more excellent appearance and excellent heat creep characteristics can be obtained.

[0079] [Molded article] As the use of the recycled styrene-based resin composition according to the present disclosure, it is preferably used for injection blow molding, a sheet body (including a film), injection molding, or extrusion molding.

[0080] [Cartridge] As an example of a molded body formed by molding the recycled styrene-based resin composition of the present disclosure, a cartridge will be described below.

[0081] The present disclosure relates to a cartridge that is detachably attached to an image forming apparatus for forming a multicolor or single-color image on a recording medium by an electrophotographic method, the cartridge having a cartridge body, a photosensitive drum, and charging means for charging the surface of the photosensitive drum. The cartridge body contains a recycled polystyrene resin (A) containing toluene-insoluble matter after osmium tetroxide treatment, and a rubber-modified polystyrene resin (B) containing rubber-like polymer particles (b2) constituting a domain phase and a polystyrene resin (b1) constituting a polymer matrix phase, and the toluene-insoluble matter after osmium tetroxide treatment is more than 0 to 10% by mass based on the entire recycled polystyrene resin composition. Provided is a cartridge using a recycled polystyrene resin composition that suppresses a decrease in mechanical strength and chemical resistance and exhibits excellent appearance and excellent heat creep characteristics. Cartridges such as drum cartridges that are detachable from the main body casing of an image forming apparatus are generally known. In the cartridge, toner and a carrier are stored in a developing container, and the cartridge is provided with a mechanism for transporting the toner together with the carrier in the developing container. On the other hand, in the main body casing of the image forming apparatus, a transfer roller for transferring the toner supplied to the photosensitive drum onto a sheet is arranged. Therefore, it has been confirmed that heat generation occurs in the photosensitive drum and the transfer roller, and creep deformation occurs in the fitting members (such as claw parts) or connection members between the cartridge itself and other members. Also, since the amount of creep deformation depends on the stress applied to each member and the environmental temperature, the amount of creep deformation differs depending on the material (resin type, metal type) of each member. As a result, a new problem has arisen that it is difficult for the photosensitive drum to rotate stably under driving. However, it has been confirmed that by using the recycled styrene-based resin composition of the present embodiment, a cartridge having extremely excellent heat-resistant creep characteristics can be formed (see the examples described later). Also, in order to reduce the amount of creep deformation, a method of inserting a reinforcing material such as a metal sheet metal into the fitting members (such as claw parts) or connection members between the cartridge itself and other members can be considered. However, by using the recycled styrene-based resin composition of the present embodiment, it is possible to provide a cartridge with a small amount of creep deformation, particularly a cartridge having a photosensitive drum, without using a reinforcing material such as a metal sheet metal.

[0082] The cartridge according to the present embodiment may be a cartridge that is attached to and detached from an image forming apparatus and includes developing means for developing an electrostatic latent image formed on the surface of an image holding body as a toner image with toner. Hereinafter, an example of the cartridge according to the present embodiment will be shown, but it is not limited thereto.

[0083] The cartridge of the present embodiment preferably has a toner container for containing toner and / or has a photosensitive drum. In other words, the cartridge of the present embodiment may be an integrated cartridge in which a toner container part (so-called toner cartridge part) for containing toner and a drum part (so-called drum cartridge part) having a photosensitive drum are integrated, or the toner cartridge (part) and the drum cartridge (part) may be a separable cartridge. Therefore, the cartridge of the present embodiment includes a toner cartridge having a toner container for containing toner, a drum cartridge having a photosensitive drum, an integrated cartridge having a toner container part for containing toner and a photosensitive drum, and a separable cartridge having the toner cartridge and the drum cartridge detachable from the toner cartridge.

[0084] Hereinafter, with reference to FIGS. 1 to 3, a drum cartridge 10 having a photosensitive drum, a toner cartridge 2 having a toner container 3 for containing toner, and an example of a separable cartridge will be described. FIG. 1 is a schematic diagram of a so-called cartridge 1. The cartridge 1 in FIG. 1 shows a separable cartridge in which a toner cartridge 2 detachable from a drum cartridge 10 is attached to the drum cartridge 10. The separable cartridge is attached to the main body housing of the image forming apparatus. In this specification, the cartridge in a state where the toner cartridge 2 is attached to the drum cartridge 10 is called a separable cartridge. That is, the separable cartridge includes a drum cartridge 10 and a toner cartridge 2. Further, FIG. 2 is a cross-sectional view of the cartridge 1 shown in FIG. 1. FIG. 3 is a schematic diagram showing a state in which the toner cartridge 2 and the drum cartridge 10 of the cartridge 1 shown in FIG. 1 are separated.

[0085] The drum cartridge 10 has a drum cartridge main body 7 and a photoreceptor drum 5. Further, the drum cartridge 10 preferably further includes a charging means 4, a cleaning roller 8, a transfer roller 11, a developing unit 9, and a conveying roller 12. Also, the toner cartridge 2 is detachable from the drum cartridge 10 (see FIG. 3). The drum cartridge main body 7 is a housing that supports the photoreceptor drum 5, the charging means 4, the cleaning roller 8, the transfer roller 11, the conveying roller 12, the developing unit 9, and the toner cartridge 2. The drum cartridge main body 7 has positioning projections (not shown) for positioning bearings (not shown). The photoreceptor drum 5 is rotatable about a drum axis extending in the axial direction. In the following description, the "axial direction" is the direction in which the drum axis of the photoreceptor drum 5 extends, and represents the X direction in FIG. 1. The "conveying direction" is the direction from the conveying roller 12 toward the transfer roller 11, and represents the Y direction in FIG. 1. The "conveying direction" is also the direction from the lower end of the conveying roller 12 toward the nip position of the sheet S such as paper by the photoreceptor drum 5 and the transfer roller 11. The direction orthogonal to the "axial direction" and the "conveying direction" is referred to as the "orthogonal direction", and represents the Z direction in FIG. 1.

[0086] The charging means 4 has the role of charging the photoreceptor drum 5. Examples of the charging means 4 include a scorotron type, a corotron type, or a charging roller. The cleaning roller 8 has the role of cleaning the photoreceptor drum 5. The cleaning roller 8 is rotatable about a cleaning roller axis extending in the axial direction. The cleaning roller 8 faces the surface of the photoreceptor drum 5, and the cleaning roller 8 is located on the downstream side in the conveying direction of the photoreceptor drum 5.

[0087] The transfer roller 11 has the role of transferring the toner supplied to the photosensitive drum 5 from the photosensitive drum 5 to the sheet S. The transfer roller 11 is rotatable about a transfer roller shaft extending in the axial direction. The transfer roller 11 faces the surface of the photosensitive drum 5, and the transfer roller 11 is located on the other side (the lower side in FIG. 1) in the direction orthogonal to the photosensitive drum 5. The transfer roller 11 can nip and convey the sheet S between the transfer roller 11 and the photosensitive drum 5.

[0088] When the drum cartridge 10 is mounted in the main body housing of the image forming apparatus, the conveyance roller 12 comes into contact with the main body roller of the image forming apparatus and rotates in a driven manner, and has the role of conveying the sheet S together with the main body roller. The conveyance roller 12 is rotatable about a conveyance roller shaft extending in the axial direction. The conveyance roller 12 is located at a predetermined distance upstream in the conveyance direction of the photosensitive drum 5.

[0089] The drum cartridge 10 may further include a drum gear as needed. The driving force input from the drum gear can be transmitted to the photosensitive drum 5, the cleaning roller 8, and the transfer roller 11 via a gear train.

[0090] The developing unit 9 is located between the conveyance roller 12 and the photosensitive drum 5 in the conveyance direction. The developing unit 9 includes a magnetic roller 6, a blade, a blade holder, a developing container, and a storage container. The magnetic roller 6 is a roller that supplies toner to the photosensitive drum 5. The magnetic roller 6 is rotatable about a magnetic roller shaft extending in the axial direction. The magnetic roller 6 faces the surface of the photosensitive drum 5 and is located upstream in the conveyance direction of the photosensitive drum 5. The magnetic roller 6 is spaced apart from the surface of the photosensitive drum 5. The developing container is a container that houses toner (not shown) and a carrier (not shown) supplied to the magnetic roller 6. The carrier can be a magnetic material. An example of the carrier is iron powder. The developing container is replenished with toner (not shown) that was housed in the toner cartridge 2 (or inside the toner housing 3). Note that the carrier may be a magnetic material other than iron powder.

[0091] The toner cartridge 2 may further have a toner coupling. The toner coupling is located at one end on the axial direction side. And the toner coupling is the part where the driving force is input from the apparatus main body of the image forming apparatus to the toner cartridge 2. The driving force input from the toner coupling is transmitted to an agitator or the like by a gear train.

[0092] In the above-described embodiment, the separable cartridge in a state where the toner cartridge 2 is mounted on the drum cartridge 10 has been described, but the cartridge 1 of the present disclosure is not limited thereto. For example, it is also applicable to a drum cartridge 10 of a type where the toner cartridge 2 is not mounted, an integral cartridge in which the toner cartridge 2 or a member accommodated in the toner cartridge 2 is accommodated in the drum cartridge 10. In the above-described embodiment, a laser printer has been exemplified as an example of the image forming apparatus, but the present disclosure is not limited thereto, and the present disclosure may be applied to other image forming apparatuses such as an inkjet printer, a copying machine, a multifunction machine, and the like.

Example

[0093] Next, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. The analysis and evaluation methods of the resins and molded products in the Examples and Comparative Examples are as follows.

[0094] [Characteristics Evaluation of Each Resin and Resin Composition] (1) Measurement of Weight-Average Molecular Weight The weight-average molecular weight (Mw) of each resin and resin composition produced in the Examples and Comparative Examples was measured under the following conditions using gel permeation chromatography (GPC). Measuring instrument: HLC-8220 manufactured by Tosoh Corporation Fractionation column: Two TSK gel Super HZM-H (inner diameter 4.6 mm) manufactured by Tosoh Corporation are connected in series Guard column: TSK guard column Super HZ-H manufactured by Tosoh Corporation Measurement solvent: Tetrahydrofuran (THF) Sample concentration: 5 mg of the measurement sample was dissolved in 10 mL of the solvent and filtered through a 0.45 μm filter. Injection volume: 10 μL Measurement temperature: 40 °C Flow rate: 0.35 mL / min Detector: Differential refractometer For the preparation of the calibration curve, 11 types of Tosoh's TSK standard polystyrenes (F-850, F-450, F-128, F-80, F-40, F-20, F-10, F-4, F-2, F-1, A-5000) were used. The calibration curve was created using a first-order linear approximation formula.

[0095] (2) Measurement of melt mass flow rate (MFR) The melt mass flow rate (g / 10 min) of each resin and resin composition produced in the examples and comparative examples was measured under the load conditions of 200 °C and 49 N in accordance with ISO 1133.

[0096] (3) Measurement of Vicat softening temperature The Vicat softening temperature of each resin and resin composition produced in the examples and comparative examples was measured in accordance with ISO 306. The load was 50 N and the heating rate was 50 °C / h.

[0097] (4) Calculation of the content (mass%) of each monomer unit of styrene-based monomer units, (meth)acrylate monomer units, and (meth)acrylic acid monomer units (NMR measurement) Proton nuclear magnetic resonance ( 1 1H-NMR) The resin composition was quantified from the integration ratio of the spectra measured with a measuring instrument. Sample preparation: 30 mg of resin pellets were heated and dissolved in 0.75 ml of d6-DMSO at 60 °C for 6 hours. Measuring instrument: JEOL JNM ECA-500 Measurement conditions: Measurement temperature 25 °C, observed nucleus 1H, number of integrations 64 times, repetition time 11 seconds (Assignment of NMR spectrum) The assignment of the spectrum measured in DMSO re-dissolving medium is as follows: the peak at 0.5 - 1.5 ppm is the hydrogen of the α-methyl group of methacrylic acid, methyl methacrylate, and six-membered cyclic anhydride; the peak at 1.6 - 2.1 ppm is the hydrogen of the methylene group in the polymer main chain; the peak at 3.5 ppm is the hydrogen of the carboxylic acid ester (-COOCH 3 ) of methyl methacrylate; the peak at 12.4 ppm is the hydrogen of the carboxylic acid of methacrylic acid. Also, the peak at 6.5 - 7.5 ppm is the hydrogen of the aromatic ring of styrene. Since the resin of this embodiment has a low content of six-membered cyclic anhydride, it is usually difficult to quantify by this measurement method.

[0098] (5) Measurement of the content of each monomer unit The content of each monomer unit contained in the resin compositions prepared in the examples and comparative examples was measured by pyrolysis GC / MS under the following conditions. <Measurement conditions> Pyrolysis unit Equipment: PY-3030D manufactured by Frontier Lab Heating furnace temperature: 600 °C Interface temperature: 300 °C GC / MS Equipment: GCMS-GP2020NX manufactured by Shimadzu Corporation Column: Ultra Alloy-5 (Length 30 m, film thickness 0.25 μm, diameter 0.250 mm φ) Column temperature: Held at 50 °C for 5 minutes, heated at 10 °C / min, Heated at 7 °C / min from 100 °C and held at 300 °C for 10 minutes. Inlet temperature: 300 °C Detector temperature: 300 °C Split ratio: 1 / 300 Carrier gas: Helium Detection method: Mass spectrometer (MSD) Sample amount: 50 μg Detection mode: Scan mode or SIM mode When detecting each monomer peak, in order to avoid peak overlap and peak intensity saturation, pre-treatments such as the dilution rate of the sample, the column used, and the detection conditions may be appropriately adjusted as needed.

[0099] (6) Measurement of rubber-like polymer particles The recycled styrene resin composition of the following examples and the resin composition of the comparative examples were stained with osmium tetroxide, and then five ultra-thin sections with a thickness of 100 nm were prepared. Using a transmission electron microscope, five bright-field images (magnification 10,000 times) were obtained respectively. Then, the five bright-field images were summed up to obtain the following formula (N1): Weight average diameter = ΣniDri 4 / ΣniDri 3 (N1) (In the above formula (N1), ni is the number of rubber-like polymer particles with a particle diameter of Dri, and the particle diameter Dri is the particle diameter calculated as the equivalent circle diameter from the area of the particles in the bright-field image.) The area average particle diameter was calculated and used as the weight average diameter of the rubber-like polymer particles. The above analysis was carried out as follows using the image analysis software ImageJ (manufactured by the National Institutes of Health, USA). The obtained image was binarized by the Otsu method and the white part (corresponding to the polymer matrix phase) other than the rubber-like polymer particles was filled. The adjacent rubber-like polymer particles in contact were separated by the Watershed process. After calculating the area of the rubber-like polymer particles, it was converted to the equivalent circle diameter. A histogram and an average value based on the number were derived from the obtained numerical group of the equivalent circle diameters. The equipment and the like used are as follows. Ultra microtome: UC7 / Leica Transmission electron microscope: HT7700 / Hitachi High-Technologies

[0100] (7) Measurement of Charpy impact strength The test pieces used for the measurement of the Charpy impact strength were strips with specified dimensions cut from the central parallel part of a 1A type dumbbell prepared by the method described in the column of "Method for manufacturing ISO dumbbell test pieces" described below. The test was carried out in accordance with ISO 179 to measure the Charpy impact strength (kJ / m 2 ) with a notch.

[0101] (8) Measurement of tensile yield stress As the test specimens used for the measurement of the tensile yield stress, 1A dumbbells prepared by the method described in the section "Manufacturing method of ISO dumbbell test specimens" below were used, with each resin composition produced in the examples and comparative examples. The test specimens were measured for the tensile yield stress (MPa) in accordance with ISO 527-1.

[0102] (9) Measurement of tensile fracture elongation Injection molded pieces were prepared from each resin composition produced in the examples and comparative examples at 220 °C in accordance with JIS K 7152, and the tensile fracture elongation (%) was measured in accordance with JIS K 7161 ISO 527-1.

[0103] (10) Measurement of flexural modulus Various resin compositions produced in the examples and comparative examples were injection molded into ISO type 1A dumbbell test specimens, and the flexural modulus (MPa) was measured in accordance with ISO 178 using strips of specified dimensions cut out from the central parallel part of the dumbbell.

[0104] (11) Measurement of heat distortion temperature under load From each resin composition produced in the examples and comparative examples, injection molded into ISO type 1A dumbbell test specimens, and the heat distortion temperature under load (unit: °C) was measured in accordance with ISO 75-1 and 75-2 using strips of specified dimensions cut out from the central parallel part of the dumbbell under the condition of a load of 1.8 MPa. Also, when measuring the heat distortion temperature under load, "AUTO HDT Tester 6A-2V" manufactured by Toyo Seiki Co., Ltd. was used.

[0105] (12) Measurement of chemical resistance (physical property retention rate) To evaluate the chemical resistance of various resin compositions produced in the examples and comparative examples, a predetermined grease (Molycoat EM-50LP: DuPont-Toray Specialty Materials Co., Ltd.) was applied to the central parallel part of an ISO type 1A dumbbell test specimen and aged in a hot air circulation oven at 60 °C for 168 hours. After wiping off the grease with a wipe, the appearance was confirmed, the tensile fracture strain was measured, and the retention rate (%) was calculated by comparing with the initial value. Drug resistance (physical property retention rate) (%) = (Tensile fracture strain of the sample after 168 - hour aging treatment with grease applied) ÷ (Tensile fracture strain of the sample without grease applied and without 168 - hour aging treatment)

[0106] (13) Measurement of heat - resistant creep characteristics A bending creep test with a three - point load in accordance with ISO899 - 2 was carried out using strips of specified dimensions cut from the central parallel part of a Type 1A dumbbell test piece. The ambient temperature was 60°C and the load was 29.4 N. The evaluation was made based on the amount of strain (mm) after a certain time (100 hours).

[0107] (14) Appearance A three - step plate with dimensions of 120×50 mm and thicknesses of 2.5 mm, 2.0 mm, and 1.0 mm was molded using an injection molding machine. Using the 2.0 - mm - thick flat part (40×50 mm) at the center of the plate, observation of black - dot foreign matters and measurement of the 60° glossiness were carried out. The black dots were sized according to the inclusion measurement chart (JIS P 8208) and the number was counted. If all the observed black dots are 0.1 mm 2 or less, it is marked as 〇, if it is more than 0.1 mm to 0.5 mm 2 and the number of those is 20 or less and more than 0.5 mm to 0.7 mm 2 and the number of those is 2 or less, it is marked as △, otherwise it is marked as ×. The glossiness was measured using a gloss meter GM26D (Murakami Color Technology Research Institute Co., Ltd.) in accordance with JIS Z 8741 for 60° specular gloss. If the glossiness is 35 or less, it is marked as △, if it is 36 or more, it is marked as 〇 (qualified).

[0108] (15) Measurement by laser diffraction method Into a disposable cup made of polypropylene, 20 mg of the recycled styrene resin composition of the example and the resin composition of the comparative example were placed, along with 20 mL of N,N-dimethylformamide, and ultrasonic vibration was applied for 15 minutes to dissolve and disperse them. While vibrating, a part of the turbid liquid of the sample was collected, placed in a measuring cell, and while stirring with a rotor, using a laser diffraction particle size measuring device (LA-960V2, manufactured by Horiba, Ltd.), the particle diameters (d84%, d50%, d16%) and the integral distribution curve of the dispersoid of the N,N-dimethylformamide solution containing the recycled styrene resin composition or the resin composition were determined. At this time, the refractive index of the sample was 1.6 - 0.00i, and the refractive index of the solvent was 1.428. In this example, the particle size distribution based on volume is adopted. For example, the volume-based particle size distribution (d 84 %-d 16 %) of the recycled styrene resin composition of Example 1 was 1.18, and the average particle diameter d 50 % was 1.7 μm. On the other hand, the number-based particle size distribution (d 84 %-d 16 %) of the recycled styrene resin composition of Example 1 was 0.90, and the average particle diameter d 50 % was 1.2 μm. Also in other examples, the average particle diameter tended to be smaller and the distribution tended to be narrower in terms of the number basis.

[0109] (16) Measurement of weld strength retention rate (flexural strength) Using the recycled styrene resin compositions obtained in the examples and comparative examples, a mold was attached to an injection molding machine (PS40E manufactured by Nissei Plastic Industrial Co., Ltd.) such that the molten resin of the recycled styrene resin composition flowed in from both ends in the length direction of a shape with a length of 125 mm, a width of 13 mm, and a thickness of 3.2 mm, and a weld was formed at the center in the length direction. Molding was performed (molding temperature: 220 °C, mold temperature: 45 °C, injection pressure: 7.5 MPa (50%), injection speed: 215 cm / min (50%), one-speed one-pressure molding) to obtain test pieces. A tensile test was carried out in a method compliant with ISO 527, except that the molded test pieces had a chuck distance of 50 mm and a tensile speed of 1.5 mm / min, and after obtaining the tensile strength, it was calculated from the following formula. The measured values were the average values of N = 5. Weld strength retention rate (%) = (Bending strength with weld) ÷ (Bending strength without weld) × 100

[0110] [Raw materials used in Examples and Comparative Examples] The properties of the recycled polystyrene resin (A), rubber-modified polystyrene resin (B), and styrene resin (C) used in the examples and comparative examples are shown in Table 1. The additives used in the examples and comparative examples are as follows.

[0111]

Table 1-1

[0112]

Table 1-2

[0113]

Table 1-3

[0114]

Table 1-4

[0115] (Additives) Antioxidant: Octadecyl 3-(3’,5’-di-t-butyl-4’-hydroxyphenyl) propionate Release agent: Zinc stearate Plasticizer: Liquid paraffin

[0116] [Examples and Comparative Examples] 「Manufacturing method of recycled styrene resin compositions of Examples 1 to 20」 The raw materials described in the column of [Raw Materials Used in Examples and Comparative Examples] above were prepared. Specifically, the content of the rubber-like polymer particles (a2) contained in the recycled polystyrene-based resins (A1) to (A8), the content of the toluene-insoluble matter (1) (= contaminants) after the osmium tetroxide treatment, and the weight-average molecular weight of the polymer matrix part (a1) were measured before melt-kneading. Also, the content of the rubber-like polymer particles (b2) contained in the rubber-modified polystyrene-based resins (B1) to (B7) and the weight-average molecular weight of the polystyrene-based resin (b1) were measured. Next, the weight-average molecular weight of the virgin material (C1) was measured. And in each example, so that the molecular weight, the content of the rubber component, the content of the contaminants (toluene-insoluble matter (1) after the osmium tetroxide treatment), and the weight-average molecular weight of the polymer component of the obtained recycled styrene-based resin composition would become predetermined values, after preparing the raw materials according to the column of [Raw Materials Used in Examples and Comparative Examples] above and Tables 2-1 to 2-3 below respectively, the weighed raw materials were blended in a drum tumbler and melt-kneaded at a cylinder set temperature of 220 °C and a screw rotation speed of 200 rpm using a twin-screw extruder (TEM-26SS manufactured by Toshiba Machine Co., Ltd.). The molten resin passed through a screen mesh provided on the upstream side of a breaker plate between the tip of the extruder screw and the die, and then was extruded as a molten strand from the die. The molten strand was water-cooled and cut with a rotary cutter to obtain the pelletized recycled styrene-based resin compositions of Examples 1 to 20. And according to the measurement method described above, the physical properties of the obtained styrene-based resin compositions of Examples 1 to 20 were measured and evaluated. The results are shown in Tables 2-1 to 2-3. In addition, in the above melt-kneading, the melt was passed through a screen mesh as necessary so that the volume-based particle size distribution (d 84 %-d 16 %) would be less than 2.

[0117] "Manufacturing Methods of Resin Compositions of Comparative Examples 1 to 6 and Reference Examples 1 to 4" According to the column of [Raw materials used in Examples and Comparative Examples] above and Table 2-4 below, after preparing the raw materials respectively, the weighed raw materials were compounded in a drum tumbler and melt-kneaded at a cylinder set temperature of 220°C and a screw rotation speed of 200 rpm using a twin-screw extruder (TEM-26SS manufactured by Toshiba Machine Co., Ltd.) and extruded as a molten strand. The molten strand was water-cooled and the strand was cut with a rotary cutter to obtain pelletized resin compositions of Comparative Examples 1 to 6 and Reference Examples 1 to 4. Then, according to the measurement method described above, the physical properties of the obtained resin compositions of Comparative Examples 1 to 6 and Reference Examples 1 to 4 were measured and evaluated. The results are shown in Table 2-4.

[0118]

Table 2-1

[0119]

Table 2-2

[0120]

Table 2-3

[0121]

Table 2-4

[0122] "Fabrication and Evaluation of Cartridges of Examples 21 to 26" Using the recycled styrene-based resin composition produced in the above examples, a cartridge housing (cartridge body) was fabricated. Specifically, the cartridge housing had a box shape with ribs set in a lattice pattern (dimensions: length 260 mm × depth 80 mm × height 80 mm), and was molded using a three-plate mold with two pin gates and a cold runner with the recycled styrene-based resin composition produced in the examples shown in Table 3 to fabricate the cartridge housing. Then, for the obtained cartridge housing, a practical creep evaluation under the following conditions was performed. The results are shown in Table 3. <Evaluation of Practical Creep Characteristics> Fix the positioning pins inside the cartridge housing to the jig. Then, with a weight of 4.6 kg (an iron weight with a diameter of 50 mm and a height of 300 mm) applied to the central part in the longitudinal direction of the cartridge housing, it was placed in an oven at 60°C, and the amount of deformation (mm) of the central part of the cartridge housing after 100 hours was measured. As a result, if the amount of deformation of the central part of the cartridge housing is within 0.5 mm, it is considered qualified (○), and if the amount of deformation exceeds 0.5 mm, it is considered unqualified (×).

[0123] "Cartridge of Comparative Example 7" Using the resin composition in the same manner as in Examples 21 to 26 above, a cartridge housing was produced. The resin composition used in Comparative Example 7 is as shown in Table 3.

[0124]

Table 3

Explanation of Symbols

[0125] 1 Cartridge 2 Toner Cartridge 3 Toner Housing 4 Charging Means 5 Photoconductor Drum 6 Magnetic Roller 7 Drum Cartridge Body 8 Cleaning Roller 9 Developing Unit 10 Drum Cartridge 11 Transfer Roller 12 Conveyor Roller

Claims

1. A recycled styrene-based resin composition comprising: a recycled polystyrene-based resin (A) containing a toluene-insoluble matter (1) after osmium tetroxide treatment; and a rubber-modified polystyrene-based resin (B) containing rubber-like polymer particles (b2) constituting a domain phase and a polystyrene-based resin (b1) constituting a polymer matrix phase, The recycled styrene-based resin composition, wherein the toluene-insoluble matter (1) after the osmium tetroxide treatment is more than 0 to 10 mass% based on the entire recycled styrene-based resin composition.

2. a polymer matrix portion (a1) of the recycled polystyrene-based resin (A) and 55 to less than 97.9% by mass of a polymer component including the polystyrene-based resin (b1); 2.1 to 35% by mass of a rubber component containing the rubber-like polymer particles (b2); the recycled polystyrene resin (A) is treated with osmium tetroxide, and the toluene insoluble matter after the osmium tetroxide treatment (1) is more than 0 to 10 mass%; The recycled styrene-based resin composition according to claim 1 .

3. 3. The recycled styrene-based resin composition according to claim 1 or 2, further comprising a styrene-based resin (C) that does not contain rubber-like polymer particles.

4. The recycled styrene-based resin composition according to claim 1 or 2, having a weight average molecular weight (Mw) in the range of 100,000 to 350,000.

5. The recycled styrene-based resin composition according to claim 1 or 2, wherein the average particle size of all rubber-like polymer particles in the recycled styrene-based resin composition is in the range of 1.6 to 3.2 μm.

6. The recycled styrene-based resin composition according to claim 1 or 2, wherein all rubber-like polymer particles in the recycled styrene-based resin composition contain conjugated diene monomer units, and the content of the conjugated diene monomer units is 2 to 15 mass% based on the total recycled styrene-based resin composition.

7. The recycled styrene-based resin composition according to claim 1 or 2, which contains one or more selected from the group consisting of antioxidants, pigments, flame retardants, additives, mineral oils, vegetable oils and lubricants.

8. The recycled styrene-based resin composition according to claim 1, wherein the content of all rubber-like polymer particles in the recycled styrene-based resin composition is 2.1 to 35 mass% based on the entire recycled styrene-based resin composition.

9. A step (I) of preparing a recycled polystyrene-based resin (A) containing a toluene-insoluble portion (1) after osmium tetroxide treatment, and a rubber-modified polystyrene-based resin (B) containing rubber-like polymer particles (b2) constituting a domain phase and a polystyrene-based resin (b1) constituting a polymer matrix phase; and (II) melt-kneading the recycled polystyrene-based resin (A) and the rubber-modified polystyrene-based resin (B).

10. A molded article obtained by molding the recycled styrene-based resin composition according to claim 1 or 2.

11. A cartridge that is detachably attached to an image forming apparatus that forms a multi-color or monochrome image on a recording medium by an electrophotographic method, a cartridge body, a photosensitive drum, and a charging means for charging the surface of the photosensitive drum; The cartridge body contains a recycled styrene-based resin composition including a recycled polystyrene-based resin (A) containing a toluene-insoluble matter (1) after osmium tetroxide treatment, and a rubber-modified polystyrene-based resin (B) containing rubber-like polymer particles (b2) constituting a domain phase and a polystyrene-based resin (b1) constituting a polymer matrix phase, and the toluene-insoluble matter (1) after osmium tetroxide treatment is more than 0 to 10 mass% of the entire recycled styrene-based resin composition.

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