Recycled styrene resin composition, molded body thereof, 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 styrene-based resin composition, and a molded article and cartridge molded using the recycled styrene-based resin composition. [Background technology]

[0002] Styrene-based resins such as polystyrene are not only tasteless and odorless, and suitable for food applications, but are also known as materials with low environmental impact because the only components generated by complete combustion are carbon dioxide gas and water vapor. In particular, waste styrene-based resins such as inner loss generated during the production process of styrene-based resin molding factories have clear quality and composition, making them easy to recycle. However, since the waste styrene resin collected from the market contains a large amount of various resins other than the waste styrene resin, metal powder, adhesions, or foreign matter, the reality is that molded products simply recycled from waste styrene resin have difficulty maintaining the same mechanical properties as molded products made from new styrene resin. For example, materials used in TV housings, refrigerator partition shelves, and multifunction printer cartridges contain a large amount of styrene resin, so there is a demand for material recycling technology for these materials. Patent Document 1 discloses a technique for suppressing deterioration of appearance design by adsorbing dibutylhydroxytoluene molecules or dibutylhydroxytoluene dimers, which are resin additives that cause resin adhesion to a mold during molding and yellowing over time, to the zeolite using a recycled styrene resin composition containing used styrene resin and zeolite. Patent Document 2 also discloses a technique for recycled polystyrene resin that contains used resin waste (C) containing polystyrene resin containing a flame retardant and a rubber component and polystyrene resin not containing a rubber component, a styrene thermoplastic elastomer (D), a bromine-based flame retardant (E), and a polyfluoroolefin (F) in order to provide a polystyrene resin that exhibits good rigidity, impact strength, moldability, and flame retardancy equivalent to that of unused polystyrene resin. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-007424 A [Patent Document 2] JP 2018-087261 A Summary of the Invention [Problem to be solved by the invention]

[0004] The techniques of Patent Documents 1 and 2 described above have been developed with regard to mechanical strength and flame retardancy, but are insufficient in terms of chemical resistance and appearance. Therefore, the problem to be solved by the present disclosure is to provide a recycled styrene-based resin composition that reduces the environmental load, suppresses a decrease in mechanical strength, and exhibits an excellent appearance, as well as a molded article and a cartridge using the same. [Means for solving the problem]

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

[0006] [1] The present disclosure relates to a recycled styrene-based resin composition comprising 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, The recycled styrene-based resin composition has a toluene-insoluble matter (1) after the osmium tetroxide treatment in an amount of more than 0 to 10 mass % based on the total mass of the recycled styrene-based resin composition. [2] The present disclosure relates to a recycled polystyrene-based resin (A) containing a toluene-insoluble portion (1) after osmium tetroxide treatment, and a rubber-like polymer particle (b2) and a polystyrene-based resin (b1), 55 to less than 97.9 mass% of a polymer component including a polymer matrix portion (a1) of the recycled polystyrene-based resin (A) and the polystyrene-based resin (b1); 2.1 to 35 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 (1) after the osmium tetroxide treatment is more than 0 to 10 mass%; The recycled styrene-based resin composition comprises: [3] The recycled styrene-based resin composition is dissolved and dispersed in N,N-dimethylformamide, and the dispersoid in the composition dispersion is represented by the following formula (1): [Number 1] 0<(|d 84% -d 16% |) / 2<2 (1) (In the above formula, d 84% represents the integrated 84% diameter in the integral distribution curve of the particle diameter of the dispersoid measured by a laser diffraction method, and d 16% represents the integrated 16% diameter in the integral distribution curve of the particle diameter of the dispersoid measured by a laser diffraction method.) The recycled styrene-based resin composition according to [1], which satisfies the above.

[0007] [4] The recycled styrene-based resin composition according to any one of [1] to [3], further comprising a styrene-based resin (C).

[0008] [5] The recycled styrene-based 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 styrene-based resin composition according to any one of [1] to [4], wherein the average particle size of all rubber-like polymer particles contained in the recycled styrene-based resin composition is in the range of 1.6 to 3.2 μm.

[0010] [7] The recycled styrene-based resin composition according to any one of [1] to [6], wherein all rubber-like polymer particles contained 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 amount of the recycled styrene-based resin composition.

[0011] [8] The recycled styrene-based resin composition according to any one of [1] to [7], containing one or more selected from the group consisting of antioxidants, pigments, flame retardants, additives, mineral oils, vegetable oils, and lubricants.

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

[0013]

[10] 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 resin (A) and the rubber-modified polystyrene resin (B), thereby producing the recycled styrene resin composition according to any one of [1] to [9].

[0014]

[11] A molded article obtained by molding the recycled styrene-based resin composition according to any one of [1] to

[10] .

[0015]

[12] 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. Effect of the Invention

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

[0017] [Figure 1] FIG. 1 is a schematic view showing an example of a cartridge according to the present embodiment. [Diagram 2] FIG. 2 is a cross-sectional view of the cartridge of FIG. [Diagram 3] FIG. 3 is a schematic diagram showing an example in which the cartridge of the present embodiment is separated into a drum cartridge and a toner cartridge. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

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

[0020] Another embodiment of the recycled styrene-based resin composition of the present disclosure comprises a recycled polystyrene-based resin (A) containing a toluene-insoluble portion (1) after osmium tetroxide treatment, and a polystyrene-based resin (b1) and rubber-like polymer particles (b2), The polymer matrix portion (a1) of the recycled polystyrene-based resin (A) and the polymer component including the polystyrene-based resin (b1) are 55 to less than 97.9 mass% with respect to the entire recycled styrene-based resin composition, The rubber component containing the rubber-like polymer particles (b2) is 2.1 to 35 mass% based on the entire recycled styrene-based resin composition, The recycled styrene-based resin composition contains a toluene-insoluble matter (1) after the osmium tetroxide treatment in an amount of more than 0 to 10 mass % based on the total mass of the recycled styrene-based resin composition. This makes it possible to provide a recycled styrene-based resin composition that suppresses deterioration in mechanical strength and chemical resistance, and exhibits excellent appearance and heat creep resistance. In this 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 portion (a1) and the polystyrene resin (b1) essentially contain a styrene monomer unit and, if necessary, contain an unsaturated carboxylic acid monomer unit described below. The polymer component is a mixture containing the polymer matrix portion (a1) of the recycled polystyrene resin (A) containing the toluene-insoluble matter (1) after osmium tetroxide treatment and the polystyrene resin (b1), and the polystyrene resin (b1) and the rubber-like polymer particles (b2) can be materials derived from the rubber-modified polystyrene resin (B). The unsaturated carboxylic acid monomer is preferably a (meth)acrylic acid monomer or a (meth)acrylic acid ester monomer. The (meth)acrylic acid monomer may be, for example, acrylic acid or methacrylic acid. The (meth)acrylic acid ester monomer may be, for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, isobutyl (meth)acrylate, cyclohexyl (meth)acrylate, dibenzyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, decyl (meth)acrylate, stearyl (meth)acrylate, etc. These may be used alone or in combination.

[0022] The recycled polystyrene resin (A) may also contain rubber-like polymer particles (a2). That is, the recycled polystyrene resin (A) may contain used rubber-modified polystyrene resin. Therefore, when the recycled polystyrene resin (A) contains the rubber-like polymer particles (a2), the recycled polystyrene resin (A) contains the polymer matrix portion (a1) of the recycled polystyrene resin (A) and the rubber-like polymer particles (a2). When the recycled polystyrene resin (A) contains rubber-like polymer particles (a2), the rubber component contains the rubber-like polymer particles (a2) and rubber-like polymer particles (b2).

[0023] When the components contained in the recycled styrene-based resin composition of this embodiment are morphologically classified, the recycled styrene-based resin composition can be classified into a polymer component, a rubber component, a toluene-insoluble matter (1) after osmium tetroxide treatment (= a contaminant derived from the recycled polystyrene-based resin (A)), and an additive component that is blended as necessary. The polymer components include a polymer matrix portion (a1) derived from the recycled polystyrene resin (A), a polystyrene resin (b1) derived from the rubber-modified polystyrene resin (B), and a styrene resin (C) that is blended as needed, and the rubber components include rubber-like polymer particles (b2) derived from the rubber-modified polystyrene resin (B) and rubber-like polymer particles (a2) derived from the recycled polystyrene resin (A) that are blended as needed. The toluene-insoluble matter (1) after the osmium tetroxide treatment also includes impurities derived from the recycled polystyrene resin (A) (e.g., other resins (e.g., olefin resins such as polyethylene resins and polypropylene resins), inorganic substances (e.g., metal powder or silica), pigments, deposits, or foreign matter). In other words, the recycled styrene-based resin composition can be classified into a polymer matrix phase composed of a styrene-based polymer (e.g., including the above-mentioned polymer matrix portion (a1), the above-mentioned polystyrene-based resin (b1), and, if necessary, a styrene-based resin (C) that does not contain rubber-like polymer particles), a rubber component containing rubber-like polymer particles (b2) dispersed (e.g., in the form of islands in a sea) in the polymer matrix phase, and impurities derived from the recycled polystyrene-based resin (A) (e.g., other resins (e.g., olefin resins such as polyethylene-based resins and polypropylene-based resins), inorganic matter (e.g., metal powder or silica), pigments, deposits, or foreign matter). Therefore, the polymer matrix phase composed of the styrene-based polymer is referred to as the "polymer component" in this specification. The "rubber component" refers to a component constituted of the rubber-like polymer particles (b2) and, if necessary, the rubber-like polymer particles (a2). It was also confirmed that the contaminants derived from the recycled polystyrene resin (A) were insoluble in toluene even after the osmium tetroxide treatment described below, and that the amount of the contaminants was constant before and after the toluene dissolution treatment after the osmium tetroxide treatment. On the other hand, the polymer component was soluble in toluene. Furthermore, it was confirmed that the rubber-like polymer particles (b2) and (a2) containing conjugated diene monomer units were insoluble in toluene, but became soluble in toluene after the osmium tetroxide treatment described below. The sum of the polymer phase (e.g., the polymer phase in the rubber-like polymer particles having a core-shell structure or salami structure) encapsulated in the rubber-like polymer particles (b2) and (a2) and the graft polymer chains (styrene polymers) having styrene monomers on the surfaces of the rubber-like polymer particles is referred to as the "occluded component" in this specification. For convenience, the "polymer component" in this specification is referred to as the component that is composed of the above-mentioned styrene polymer and is soluble in toluene in the recycled styrene resin composition before the osmium tetroxide treatment. On the other hand, the "occluded component" is a component that is composed of the styrene-based polymer and is obtained by subtracting from the toluene-insoluble components in the recycled styrene-based resin composition before the osmium tetroxide treatment the total amount of the toluene-insoluble matter after the osmium tetroxide treatment of the toluene-insoluble components (= toluene-insoluble matter (1) after osmium tetroxide treatment) and the amount of the rubber-like polymer. In addition, in this specification, the term "toluene-insoluble matter after osmium tetroxide treatment (1)" refers to a process in which a recycled styrene-based resin composition or a recycled polystyrene-based resin (A) is dissolved in toluene to separate it into a toluene-soluble component and a toluene-insoluble component, and then the toluene-insoluble component is treated with osmium tetroxide to break the carbon-carbon double bond, and then further dissolved in toluene to separate it into a toluene-soluble component after osmium tetroxide treatment and a toluene-insoluble component after osmium tetroxide treatment. The toluene-insoluble component after osmium tetroxide treatment is referred to as "toluene-insoluble matter after osmium tetroxide treatment (1)". In the specification, for the sake of convenience, numbers are attached to both to distinguish them from the toluene-insoluble matter before osmium tetroxide treatment (2). They then found that when the size of the impurities derived from the recycled polystyrene resin (A) shows a certain particle size distribution, they are less likely to become the starting point of cracks, and defined the relational equation (1) described below.

[0024] In the recycled styrene-based resin composition of this embodiment, the upper limit of the rubber component content 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, or 4.6% by mass or less, preferably. On the other hand, the lower limit of the rubber component content is preferably 2.1 mass% or more, 2.7 mass% or more, 3.1 mass% or more, 3.7 mass% or more, 4 mass% or more, 6 mass% or more, 7 mass% or more, 8 mass% or more, 9 mass% or more, 9.3 mass% or more, 9.5 mass% or more, or 10 mass% or more, based on the entire recycled styrene-based resin composition. The upper limit value and the lower limit value can be combined as appropriate. When the content of the rubber component is within the above range, the effect of improving heat creep resistance and chemical resistance is achieved. The content of the rubber component is calculated as the value obtained by subtracting the toluene insoluble matter (1) after the osmium tetroxide treatment from the toluene insoluble matter (2) before the osmium tetroxide treatment, as described later.

[0025] In the recycled styrene-based 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, based on the entire recycled styrene-based 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. The upper limit value and the lower limit value can be combined as appropriate. 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. Moreover, the polymer component may further contain a styrene-based resin (C) in addition to the polymer matrix portion (a1) of the recycled polystyrene-based resin (A) and the polystyrene-based resin (b1). In the polymer component of the present embodiment, the styrene monomer units are preferably 50 to 100 mass%, the (meth)acrylic acid monomer units are 0 to 20 mass%, and the (meth)acrylic acid ester monomer units are preferably 0 to 50 mass%, and more preferably the styrene monomer units are 55 to 100 mass%, the (meth)acrylic acid monomer units are 0 to 15 mass%, and the (meth)acrylic acid ester monomer units are 0 to 45 mass%, based on the entire polymer component. In this 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, even more preferably 110,000 to 280,000, still 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 having an excellent practical balance between impact strength and fluidity can be obtained. The weight average molecular weight can be measured by gel permeation chromatography using polystyrene as the standard.

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

[0027] The upper limit of the content of the recycled polystyrene resin (A) containing the toluene-insoluble matter (1) after the 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, or 40% by mass or less relative to the entire recycled styrene resin composition (100% by mass). When the content of the recycled polystyrene resin (A) is 70% by mass or less, better impact resistance can be exhibited. On the other hand, the lower limit of the content of the recycled polystyrene-based resin (A) containing the toluene-insoluble matter (1) before the osmium tetroxide treatment in this embodiment is preferably 1 mass% or more, 10 mass% or more, 20 mass% or more, 30 mass% or more, 40 mass% or more, 50 mass% or more, or 60 mass% or more relative to the entire recycled styrene-based resin composition (100 mass%). When the content of the recycled polystyrene resin (A) is 30% by mass or more, a more excellent reduction in the environmental load can be achieved. The upper and lower limits of the content of the recycled polystyrene resin (A) can be arbitrarily combined.

[0028] The upper limit of the content of the rubber-modified polystyrene-based 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, or 40% by mass or less, based on the entire recycled styrene-based resin composition (100% by mass). If the content of the rubber-modified polystyrene-based resin (B) is 70% by mass or less, a more excellent reduction in the environmental load can be achieved. On the other hand, the lower limit of the content of the rubber-modified polystyrene-based resin (B) in this embodiment is preferably 1 mass% or more, 10 mass% or more, 20 mass% or more, 30 mass% or more, 40 mass% or more, 50 mass% or more, or 60 mass% or more, relative to the entire recycled styrene-based resin composition (100 mass%). When the content of the rubber-modified polystyrene resin (B) is 30% by mass or more, better impact resistance can be exhibited. The upper and lower limits of the content of the rubber-modified polystyrene resin (B) can be arbitrarily combined. In this embodiment, the upper limit of the content of the rubber-like polymer particles (b2) 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, or 24% by mass or less, based on the entire recycled styrene-based 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, or 11% by mass or more based on the entire recycled styrene-based resin composition (100% by mass). The content of the rubber-like polymer particles (b2) is calculated as a toluene-insoluble matter described later.

[0029] (Preferable form of rubber component) The average particle size of the rubber component in this embodiment or the average particle size of all rubber-like polymer particles contained in the recycled styrene-based resin composition is preferably 1.6 to 3.2 μm, and more preferably 1.7 to 2.8 μm, from the viewpoint of improving impact resistance and chemical resistance. The average particle size of all the rubbery polymer particles contained in the rubber component or the recycled styrene resin composition can be measured by the method for measuring the average particle size of the rubbery polymer particles (b2) described below. The average particle size of all the rubber-like polymer particles refers to the average particle size of the total particles of the rubber-like polymer particles (b2) and the optional rubber-like polymer particles (a2). When the average particle size and content of the rubber-like polymer particles are within the above range, impact resistance and rigidity are improved in a well-balanced manner.

[0030] (Toluene insolubles) In the recycled styrene-based resin composition of this embodiment, the "toluene-insoluble matter" refers to the components that are not dissolved in toluene after 1 g of the target material, such as the recycled styrene-based resin composition or the recycled polystyrene-based resin (A), is added to 20 ml of toluene and shaken at 23°C for 2 hours. And, "recycled styrene resin composition or recycled polystyrene resin (A) before osmium tetroxide treatment" refers to a recycled styrene resin composition or recycled polystyrene resin (A) that has not been treated with osmium tetroxide. Therefore, the toluene-insoluble matter present in the recycled styrene resin composition or recycled polystyrene resin (A) before osmium tetroxide treatment includes the rubber-like polymer particles (b2) contained in the rubber-modified polystyrene resin (B), components derived from the recycled polystyrene resin (A) (rubbers other than the rubber-like polymer particles (b2) (e.g., rubber-like polymer particles (a2)), metals, other resins (e.g., olefin resins such as polyethylene resins and polypropylene resins), pigments, deposits or foreign matter), etc. On the other hand, "recycled polystyrene resin (A) containing toluene-insoluble matter (1) after osmium tetroxide treatment" refers to recycled polystyrene resin (A) that contains toluene-insoluble matter remaining in the osmium tetroxide-treated recycled polystyrene resin (A) that has been treated with osmium tetroxide, compared to recycled polystyrene resin (A) before osmium tetroxide treatment. The toluene-insoluble matter in the recycled styrene-based resin composition after osmium tetroxide treatment or in the recycled polystyrene-based resin (A) after osmium tetroxide treatment contains components derived from the recycled polystyrene-based resin (A) (other resins (e.g., olefin resins such as polyethylene-based resins and polypropylene-based resins), inorganic matter (e.g., metal powder or silica), pigments, adhesions or foreign matter). As shown in the Reference Examples described later, when a styrene-based virgin material containing unused styrene-based monomer units (for example, unused resins such as styrene-based resin (C) and rubber-modified polystyrene-based resin (B)) was treated with osmium tetroxide and the amount of toluene insoluble matter was measured, it was confirmed that the virgin material contained substantially no toluene insoluble matter. Therefore, the content of toluene insoluble matter contained in the styrene-based virgin material after osmium tetroxide treatment in which the styrene-based virgin material was treated 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, or below the detection limit, based on the composition or the entire styrene-based virgin material.

[0031] In this embodiment, the method for measuring the amount of toluene insoluble matter in the recycled styrene resin composition or recycled polystyrene resin (A) is as follows. 1 g of the recycled styrene resin composition or recycled polystyrene resin (A) to be measured is precisely weighed into a precipitation tube, 20 mL of toluene is added, and the mixture is shaken at 23°C for 2 hours, and then centrifuged for 60 minutes at a temperature of 4°C, a rotation speed of 20,000 rpm, and a centrifugal acceleration of 45,100 x G in a centrifuge (manufactured by Sakuma Seisakusho Co., Ltd., SS-2050A rotor: 6B-N6L). The precipitation tube is slowly tilted at about 45 degrees, and the supernatant liquid is decanted and removed. The mass of the insoluble matter containing toluene is precisely weighed, and this mass is designated as W1. Subsequently, the mixture is vacuum dried at 160°C and 3 kPa or less for 1 hour, and then cooled to room temperature in a desiccator, and the mass of the toluene insoluble matter is precisely weighed, and this mass is designated as W2. Then, the toluene insoluble matter is recovered from the precipitation tube. The swelling index of the toluene insoluble matter was calculated by the following formula: Swelling index of the toluene insoluble matter = (W1 / W2)

[0032] (Osmium tetroxide treatment) The osmium tetroxide treatment in this embodiment refers to a chemical treatment that utilizes an oxidation reaction by osmium tetroxide in which two hydroxyl groups are added to a carbon-carbon unsaturated bond such as an alkene group by syn-addition. 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 (e.g., a rubber component or a toluene-insoluble matter) to convert it into a diol, and then the carbon-carbon unsaturated bond such as the alkene group can be cleaved by a peroxide that can be added together with the osmium tetroxide. Therefore, it has been confirmed that when a recycled styrene-based resin composition or a recycled polystyrene-based resin (A) is treated with osmium tetroxide, the rubber component (conjugated diene structure) contained in the recycled styrene-based resin composition or the recycled polystyrene-based resin (A) is solubilized in a solvent (e.g., toluene), and impurities derived from the recycled polystyrene-based resin (A) (other resins (e.g., olefin resins such as polyethylene-based resins and polypropylene-based resins), inorganic matter (e.g., metal powder or silica), pigments, adhesions or foreign matter) contained in the recycled styrene-based resin composition or the recycled polystyrene-based resin (A) remain. For the above reasons, in this specification, the contaminants derived from recycled polystyrene resin (A) that are mixed in when recycled polystyrene resin (A) is recovered for reuse are defined as toluene-insoluble matter (1) after osmium tetroxide treatment. The osmium tetroxide treatment in this embodiment is not particularly limited as long as the conditions are such that the rubber component (conjugated diene structure) contained in the recycled styrene-based resin composition or the recycled polystyrene-based resin (A) is soluble in toluene. For example, the treatment is preferably carried out according to the following procedure. The osmium tetroxide treatment in this embodiment preferably includes a step (I) of preparing an osmium tetroxide decomposition agent, and a step (II) of contacting the osmium tetroxide decomposition agent with the recycled styrene-based resin composition or the toluene-insoluble portion of the recycled polystyrene-based resin (A). In the step (I), 30 to 500 mg of osmium (VIII) oxide (for example, It is preferable to mix 100 mg of the osmium tetroxide solution, 50 to 1,400 g (e.g., 200 g) of an aqueous t-butyl hydroperoxide solution (concentration: 40 to 80% by mass, for example, 70% by mass), and 90 to 1,500 ml (e.g., 300 ml) of a lower alcohol (e.g., t-butyl alcohol) to obtain an osmium tetroxide decomposition agent. In the step (II), it is preferable to prepare a toluene-insoluble-containing solution by dissolving the recovered toluene-insoluble matter in an organic solvent (e.g., chloroform), add an osmium tetroxide decomposition agent to the toluene-insoluble-containing solution, and bring the osmium tetroxide decomposition agent into contact with the toluene-insoluble matter under reflux at 70 to 90°C (e.g., in a hot water bath at 90°C) for 10 to 30 minutes (e.g., 12 minutes). In the step (II), unsaturated bonds such as alkenes contained in the toluene-insoluble matter were decomposed. After the step (II), a recovery step (III) may be provided for recovering the solid and liquid components after the decomposition treatment. An example of the recovery step (III) preferably includes a precipitation step (IV) in which the toluene-insoluble component-containing solution to which the osmium tetroxide decomposition agent has been added is cooled, and then methanol is added to the solution while stirring to precipitate the methanol-insoluble component by the addition of methanol, and a washing step (V) in which the methanol-insoluble component and the liquid component are separated using a glass filter, the recovered methanol-insoluble component is repeatedly washed with toluene, and the component remaining on the glass filter is recovered as the toluene-insoluble component.

[0033] In the recycled styrene-based resin composition of this embodiment, the toluene-insoluble matter contained in the recycled styrene-based resin composition after treatment with osmium tetroxide is from more than 0 to 10 mass%, preferably from 0.0001 to 5 mass%, more preferably from 0.0001 to 3 mass%, even more preferably from 0.0001 to 1 mass%, and particularly preferably from 0.0001 to 0.5 mass%, based on the entire recycled styrene-based resin composition. From the viewpoint of impact resistance, it is preferable that the toluene insoluble content in the recycled styrene-based resin composition after the osmium tetroxide treatment is in the range of more than 0 to 10% by mass.In particular, it is preferable from the viewpoint of appearance and each mechanical property that the toluene insoluble content in the recycled styrene-based resin composition after the osmium tetroxide treatment is in the range of 0.0001 to 1% by mass.

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

[0035] The average particle size of the rubber-like polymer particles (a2) contained in the recycled polystyrene-based resin (A) of this embodiment before the osmium tetroxide treatment is preferably 0.1 to 4.0 μm, more preferably 0.3 to 3.8 μm, from the viewpoint of impact resistance. The average particle size of the rubber-like polymer particles (a2) contained in the recycled polystyrene-based resin (A) before the osmium tetroxide treatment can be measured by the method for measuring the average particle size of the rubber-like polymer particles (b2) described below. As a preferred form of the rubber-like polymer particles (a2), the following form of the rubber-like polymer particles (b2) can be applied.

[0036] <Integral distribution curve> In this embodiment, the dispersoid in the recycled styrene-based resin composition dispersion obtained by dissolving and dispersing the recycled styrene-based resin composition in N,N-dimethylformamide has the following formula (1): [Number 2] 0<(|d 84% -d 16% |) / 2<2 (1) (In the above formula, d 84% represents the integrated 84% diameter in the integral distribution curve of the particle diameter of the dispersoid measured by a laser diffraction method, and d 16% represents an integrated 16% diameter in an integral distribution curve of the particle diameter of the dispersoid measured by a laser diffraction method. This makes it possible to provide a recycled styrene-based resin composition that reduces the environmental impact and has excellent mechanical strength. The dispersoid is composed of a toluene-insoluble matter (1) (e.g., the above-mentioned contaminants) after osmium tetroxide treatment 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. The dispersoid is a particle having a 16% diameter (d 16% ) and the 84% diameter (d 84% ) (hereinafter, d 84% -d 16% The absolute value of the toluene-insoluble component after osmium tetroxide treatment derived from the recycled polystyrene resin (A) contained as a dispersoid is more than 0 and less than 2. This results in excellent mechanical properties. Although the details of the reason for this are unclear, it is thought that the particles are relatively small, which is unlikely to become the starting point of cracks.

[0037] The laser diffraction method is used in particle size measuring devices that utilize the fact that the angular distribution of the forward diffracted light intensity of a laser beam by particles assumed to be spherical is a function of the particle size of the particles. More specifically, it is a method in which monochromatic light such as a laser beam is projected onto a flow path of a suspension in which particles assumed to be spherical are dispersed, the diffracted light of the particles to be measured that cross the laser beam and pass through it one after another is made into a plane wave by a lens system, 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. The laser diffraction method can provide a particle size distribution based on numbers or volumes, with the horizontal axis representing the equivalent spherical diameter and the vertical axis representing the frequency (%). In this specification, the volumetric basis is used. Therefore, in this specification, the term "particle size distribution" refers to the particle size distribution of the dispersoids, where the horizontal axis indicates the sphere-equivalent diameter and the vertical axis indicates the frequency (%) (the volume fraction (%) of the dispersoids (= the toluene-insoluble matter (1) derived from the recycled polystyrene resin (A) after osmium tetroxide treatment and all rubber-like polymer particles in the recycled styrene resin composition) having various sphere-equivalent diameters). In this specification, the term "integral distribution curve" refers to a curve obtained by integrating the equivalent sphere diameters of dispersoids when the horizontal axis indicates the equivalent sphere diameter and the vertical axis indicates the integrated value of the frequency (%). The integral distribution curve is a function obtained by integrating the particle size distribution. The volume fraction indicates the volume ratio when the dispersoid obtained in the measurement of the particle size is regarded as a sphere. In the recycled styrene-based resin composition of this embodiment, the dispersoid has a 16% diameter (d 16% ) and the 84% diameter (d 84% ) and the absolute value of the difference (hereinafter, 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. In addition, the particle diameter distribution of the dispersoid is integrated into an integral distribution curve (volume-based particle diameter distribution) obtained by integrating the particle diameter distribution of the dispersoid. In this case, the integrated value of the frequency (%) (hereinafter referred to as the integrated value) is 16%. 16% ) and the 84% diameter (d 84% ) and the absolute value of the difference (hereinafter, d 84% -d 16% is more 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% Examples of the means for controlling the absolute value of 1 / 2 to be more than 0 and less than 2 μm include a means for blending (mixing) the recycled styrene-based resin (A) and the styrene-based resin (B) and then sieving them through a mesh that passes through a screen mesh, a means for crushing or pulverizing the recycled styrene-based resin (A) with a pulverizer, or a means for using the recycled styrene-based resin (A) crushed or pulverized with a pulverizer, etc. Examples of the pulverizer include a ball mill (e.g., a tumbling ball mill), a roller mill, a planetary mill, an agitating mill, etc.

[0038] In the integral distribution curve (number-based particle size distribution) of the dispersoid in this embodiment, the 84% diameter (d 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 integral distribution curve (volume-based particle size distribution) of the dispersoid in this embodiment, the 84% diameter (d 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 integral distribution curve (number-based particle size distribution) of the dispersoid in this embodiment, the 16% diameter (d 16%) is preferably from 0.05 μm to 4.0 μm, more preferably from 0.1 μm to 3.0 μm, and even more preferably from 0.2 μm to 2.0 μm. In the integral distribution curve (volume-based particle size distribution) of the dispersoid in this embodiment, the 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 even more preferably 0.3 μm or more and 3.0 μm or less.

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

[0040] (Rubber-modified polystyrene resin (B)) The rubber-modified polystyrene resin (B) of this embodiment contains rubber-like polymer particles (b2) constituting the domain phase and polystyrene resin (b1) constituting the polymer matrix phase. More specifically, the rubber-modified polystyrene resin (B) is a dispersion of particles of a rubber-like polymer (b) (hereinafter, rubber-like polymer particles (b2)) in the polystyrene resin (b1) as the polymer matrix phase, and can be produced by polymerizing a styrene monomer in the presence of the rubber-like polymer (b). Examples of the polystyrene resin (b1) include polystyrene polymers (polystyrene and / or polystyrene-unsaturated carboxylic acid polymers, etc.). Moreover, the rubber-modified polystyrene-based resin (B) of the present embodiment is preferably a virgin material, that is, an unused material.

[0041] Examples of the styrene-based monomer constituting the rubber-modified polystyrene-based resin (B) of this embodiment include, in addition to styrene, α-methylstyrene, α-methyl p-methylstyrene, ο-methylstyrene, m-methylstyrene, p-methylstyrene, vinyltoluene, ethylstyrene, isobutylstyrene, and t-butylstyrene, or styrene derivatives such as bromostyrene and indene. Styrene is particularly preferred. These styrene-based monomers can be used alone or in combination. In this embodiment, polystyrene is a homopolymer obtained by polymerizing the styrene-based monomer, and generally available ones can be appropriately selected and used.

[0042] In this embodiment, the polystyrene resin (b1) constituting the polymer matrix phase of the rubber-modified polystyrene 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 monomer unit composed of the above-mentioned styrene monomer. The polymer may also be a copolymer of the above-mentioned styrene monomer and an unsaturated carboxylic acid monomer. Therefore, the monomer constituting the polystyrene resin (b1) constituting the polymer matrix phase of the rubber-modified polystyrene resin (B) or the polystyrene resin (b1) contained in a part of the rubber-like polymer particles (b2) includes an unsaturated carboxylic acid monomer other than the above-mentioned styrene monomer. The unsaturated carboxylic acid monomer is preferably a (meth)acrylic acid monomer and a (meth)acrylic acid ester monomer. The (meth)acrylic acid monomer may be, for example, 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, dibenzyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, decyl (meth)acrylate, stearyl (meth)acrylate, etc. These may be used alone or in combination.

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

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

[0045] The rubber-like polymer particles (b2) contained in the rubber-modified polystyrene-based resin (B) of this embodiment may, for example, contain a resin or polystyrene-based polymer containing a styrene monomer unit obtained from the above-mentioned styrene-based monomer inside the rubber-like polymer particles (b2), and / or may be a resin or polystyrene-based polymer containing a styrene monomer unit grafted onto the surface of the rubber-like polymer particles (b2). More specifically, the rubber-like polymer particles (b2) in this embodiment may be particles containing a rubber-like polymer (b). Therefore, the form of the rubber-like polymer particles (b2) includes solid particles made of a rubber-like polymer (b), hollow particles made of a rubber-like polymer (b), encapsulated particles in which a phase containing a polymer constituting the polystyrene-based resin (b1) is encapsulated in the rubber-like polymer (b) (including a microphase separation structure, a core-shell structure, and a salami-type structure), and surface-grafted particles in which a polymer constituting the polystyrene-based resin (b1) is grafted onto the surface. These forms may also be combined. In this specification, the term "styrene monomer unit" refers to a repeating unit constituting a polymer obtained by polymerizing a styrene monomer, and is a repeating unit (or structural unit) in which the carbon-carbon double bond in the styrene monomer becomes a single bond (-CC-) through a polymerization reaction or crosslinking reaction of the styrene monomer. Other "monomer units" in this specification have the same meaning.

[0046] The rubber-like polymer (b) of this embodiment may have a conjugated diene structure. Therefore, the rubber-like polymer (b) is a conjugated diene-based polymer having a conjugated diene monomer unit, and for example, a rubber component such as polybutadiene, polyisoprene, natural rubber, polychloroprene, styrene-butadiene copolymer, or acrylonitrile-butadiene copolymer can be used. The rubber component may also include a form containing a polystyrene-based resin (b1) such as polystyrene and / or polystyrene-unsaturated carboxylic acid-based polymer. Among them, the rubber-like polymer (b) is preferably polybutadiene or a styrene-butadiene copolymer. As the polybutadiene, both high-cis polybutadiene having a high cis content and low-cis polybutadiene having a low cis content can be used. In addition, both random structure and block structure can be used as the structure of the styrene-butadiene copolymer. One or more of these rubber-like polymers (b) can be used. In addition, saturated rubber obtained by hydrogenating butadiene rubber can also be used. Since the rubbery polymer (b) constituting the rubbery polymer particles (b2) of this embodiment has a conjugated diene structure, the rubbery polymer particles (b2) can be solubilized in an organic solvent such as toluene by the above-mentioned osmium tetroxide treatment.

[0047] Examples of the rubber-modified polystyrene resin (B) of this 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., with HIPS (high impact polystyrene) being particularly preferred. When the rubber-modified polystyrene resin (B) is a HIPS resin, the particularly preferred rubber-like polymer (b) is a high-cis polybutadiene having 90 mol % or more of cis-1,4 bonds. In the high-cis polybutadiene, the vinyl 1,2 bonds are preferably 6 mol % or less, and more preferably 3 mol % or less. The content of isomers having a cis-1,4 structure, a trans-1,4 structure, or a vinyl-1,2 structure as structural unit isomers of the high-cis polybutadiene can be measured using an infrared spectrophotometer and calculated by processing the data according to the Morello method. The high-cis polybutadiene can be easily obtained by a known production method, for example, by polymerizing 1,3-butadiene using a catalyst containing an organoaluminum compound and a cobalt or nickel compound. In this embodiment, when a conjugated diene polymer containing (meth)acrylonitrile such as an acrylonitrile monomer unit is used as a 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 mass% or less, more preferably 5 mass% or less, even more preferably 3 mass% or less, and particularly preferably 0.7 mass% or less, relative to the entire recycled styrene-based resin composition (100 mass%).

[0048] The content of the rubber-like polymer (b) contained in the rubber-modified polystyrene resin (B) of this embodiment is preferably 2 to 15 mass%, more preferably 2.2 to 10 mass%, and even more preferably 2.4 to 8 mass%, based on 100 mass% of the total amount of the rubber-modified polystyrene resin (B). From another viewpoint, it is preferably 2.6 to 6 mass%, and more preferably 3 to 5 mass%. If the content of the rubber-like polymer (b) is less than 2.1 mass%, there is a risk of the impact resistance decreasing. Also, if the content of the rubber-like polymer (b) is more than 15 mass%, there is a risk of the gloss decreasing and the bending creep property decreasing. In the present disclosure, the content of the rubber-like polymer (b) contained in the rubber-modified polystyrene-based resin (B) (so-called polybutadiene content) is a value calculated using pyrolysis gas chromatography.

[0049] The content of the rubber-like polymer particles (b2) contained in the rubber-modified polystyrene-based resin (B) of this embodiment (toluene-insoluble content in the rubber-modified polystyrene-based resin (B)) is preferably 8 to 35 mass% relative to 100 mass% of the total amount of the rubber-modified polystyrene-based resin (B). In this disclosure, the content of the rubber-like polymer particles (b2) or the total rubber-like polymer particles contained in the rubber-modified polystyrene resin (B) or the recycled styrene resin composition corresponds to the toluene-insoluble content of the resin (B) or the composition before the osmium tetroxide treatment. Specifically, it is calculated by the following method. The content (mass%) of the rubber-like polymer particles (b2) in the composition was measured by precisely weighing 1 g of the resin or composition to be measured in a precipitation tube (this mass is W), adding 20 mL of toluene, shaking at 23 ° C. for 2 hours, and then centrifuging at 5 ° C. or less and 20,000 rpm (centrifugal acceleration: 4510 G) for 60 minutes in a centrifuge (Sakuma Seisakusho, SS-2050A). Then, the precipitation tube was slowly tilted at about 45 degrees, the supernatant liquid was decanted off, and the obtained insoluble matter was subsequently vacuum-dried for 1 hour under conditions of 160 ° C. and 3 kPa or less, cooled to room temperature in a desiccator, and the mass of the toluene-insoluble matter was precisely weighed (this mass is G), and the content (mass%) of the rubber-like polymer particles (b2) was calculated by the following formula. Content of rubber-like polymer particles (b2) = (G / W) x 100

[0050] The average particle size of the rubber-like polymer particles (b2) contained in the rubber-modified polystyrene resin (B) of this embodiment is preferably 0.5 to 3.0 μm, more preferably 0.8 to 2.8 μm, from the viewpoint of impact resistance. From another viewpoint, it is preferably 0.55 to 3.2 μm, more preferably 0.65 to 2.8 μm. If the average particle size of the rubber-like polymer particles (b2) is smaller than 0.5 μm or larger than 3.0 μm, there is a risk that the impact strength and chemical resistance will be insufficient and the gloss will be reduced.

[0051] In the present disclosure, the average particle size of the rubber-like polymer particles (b2) contained in the rubber-modified polystyrene-based resin (B) can be measured by the following method. A 75 nm thick ultrathin section 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 the rubber-like polymer particles (b2). From the photograph, the following formula (N1): [Number 3] Average particle size=ΣniDri 3 / ΣniDri 2 (N1) (In the above formula (N1), ni is the number of rubber polymer (a) particles having a particle diameter Dri, and the particle diameter Dri is the particle diameter calculated as a circle-equivalent diameter from the area of ​​the particle in the photograph.) The area-average particle size is calculated by the above and is regarded as the average particle size of the rubber-like polymer particles (b2). In this measurement, a photograph is scanned at a resolution of 200 dpi, and the measurement is performed using 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, more preferably in the range of 0.55 to 0.80 dL / g. If it is less than 0.50 dL / g, there is a risk of a decrease in impact strength, and if it exceeds 0.85 dL / g, there is a risk of a decrease in moldability due to a decrease in fluidity. In the present disclosure, the reduced viscosity of the rubber-modified polystyrene-based resin (B) is a value measured in a toluene solution at 30° C. and a concentration of 0.5 g / dL. 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, more preferably 127,000 to 250,000. In another embodiment, the weight average molecular weight (Mw) of the polystyrene resin (b1) may 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 having excellent practical balance between impact strength and fluidity can be obtained. The weight average molecular weight can be measured by gel permeation chromatography using polystyrene as the standard.

[0053] The method for producing the rubber-modified polystyrene resin (B) of this embodiment is not particularly limited, but it can be produced by bulk polymerization (or solution polymerization) in which a styrene monomer and an optionally added unsaturated carboxylic acid monomer (and a solvent) are polymerized in the presence of the rubber-like polymer (b), or bulk-suspension polymerization in which the reaction is changed to suspension polymerization during the reaction, or emulsion graft polymerization in which a styrene monomer and an optionally added unsaturated carboxylic acid monomer are polymerized in the presence of the rubber-like polymer (b) latex. In bulk polymerization, the rubber-like polymer (b) can be produced by continuously supplying a mixed solution containing the rubber-like polymer (b), the styrene monomer, and an optionally added unsaturated carboxylic acid monomer, as well as an organic solvent, an organic peroxide, and / or a chain transfer agent, to a polymerization apparatus consisting of a complete mixing reactor or a tank reactor and a plurality of tank reactors connected in series.

[0054] In this 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 even 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 resin has good mixability with the recycled polystyrene resin (A) and good mechanical strength. In the present disclosure, the melt flow rate is a value measured at 200°C under a load of 49 N in accordance with ISO 1133. The above are the essential components of the recycled styrene resin composition of this embodiment. Hereinafter, the optional components of the recycled styrene resin composition of this embodiment, the styrene resin (C) and optional additional components, will be described.

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

[0056] [Optional added ingredients] In this embodiment, at any stage before or after the recovery step in producing the recycled polystyrene resin (A), rubber-modified polystyrene resin (B) or optional component, or at the stage of extruding or molding the recycled styrene resin composition, various additives, for example, plasticizers such as liquid paraffin, ultraviolet absorbers, light stabilizers, hindered phenol-based, phosphorus-based, 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 may be added as necessary within a range that does not impair the object of the present invention. The recycled styrene-based resin composition according to this embodiment preferably contains one or more selected from the group consisting of antioxidants, pigments, flame retardants, additives, mineral oils, vegetable oils, and lubricants.

[0057] The light stabilizer of this embodiment does not have ultraviolet absorbing ability by itself, but it preferably has a function of capturing and detoxifying photoradicals generated by the recycled styrene-based resin composition absorbing ultraviolet light, thereby preventing deterioration and coloration of the composition caused by radicals. The light stabilizer can be used alone or in combination of two or more kinds, and by using it in combination with an ultraviolet absorber and / or an antioxidant described later, a higher light resistance effect can be achieved. Examples of the light stabilizer of this embodiment include bis(1,2,2,6-pentamethyl-4-piperidyl)sebacate, bis(1-undecaneoxy-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'-bis(2,2,6,6-tetramethylpiperidin-4-yl)hexane-1,6-diamine, butyl(3,5-di-t-butyl-4-hydroxypropyl) Specific product names include ADK STAB LA-52, ADK STAB LA-57, ADK STAB LA-63P, ADK STAB LA-68, ADK STAB LA-72, ADK STAB LA-77Y, ADK STAB LA-77G, ADK STAB LA-81, manufactured by ADEKA CORPORATION, JF-90G and JF-95, manufactured by Johoku Chemical Co., Ltd., and Chimassorb 2020FDL, Chimassorb 944FDL, and Tinuvn 622SF, manufactured by BASF Japan Ltd.

[0058] The ultraviolet absorber of this embodiment absorbs ultraviolet light absorbed by the recycled styrene-based resin composition on behalf of the recycled styrene-based resin composition and converts it into heat or chemical energy, thereby suppressing the generation of photoradicals due to ultraviolet light absorption by the styrene-based resin composition and suppressing deterioration and discoloration of the resin. Preferred ultraviolet absorbing agents in this embodiment include, for example, benzotriazole-based compounds, triazine-based compounds, benzophenone-based compounds, and benzoate-based compounds. Examples of preferred antioxidants in this embodiment include hindered phenol-based antioxidants such as octadecyl-3-(3,5-tertiary butyl-4-hydroxyphenyl)propionate and 4,6-bis(octylthiomethyl)-o-cresol (product name, for example, Irganox1076 manufactured by BASF Japan Ltd.), and phosphorus-based processing heat stabilizers such as tris(2,4-di-tertiary butylphenyl)phosphite (product name, for example, Irgafos168 manufactured by BASF Japan Ltd.). These stabilizers may be used alone or in combination of two or more kinds as appropriate. There is no particular restriction on the timing of addition, and it may be either the polymerization process or the devolatilization process. The stabilizer may also be mixed into the product using a mechanical device 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 relative to the total amount of the recycled styrene-based resin composition, with the upper limit being 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, and 0.7% by mass or less being preferred in this order, and the lower limit being 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, and 0.17% by mass or more being preferred in this order. The content can be selected from any combination of the upper and lower limits described above.

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

[0061] In addition, the above-mentioned various additives in the recycled styrene-based resin composition of this embodiment are preferably 10.0 mass% or less, more preferably 5.5 mass% or less, even more preferably 2.9 mass% or less, even more preferably 1.5 mass% or less, and particularly preferably 0.9 mass% or less, relative to 100 mass% of the recycled styrene-based resin composition.

[0062] [Physical properties of recycled styrene-based resin composition] Preferred physical properties of the recycled styrene-based resin composition in this embodiment are described below. <Vicat softening temperature> In this embodiment, the Vicat softening temperature of the styrene-based resin composition is preferably 88° C. or higher, more preferably 91° C. or higher, and even more preferably 93° C. or higher. By adjusting 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 in accordance with ISO306 under conditions of a load of 5 kg and a heating rate of 50° C. / h.

[0063] <Charpy impact strength> The Charpy impact strength of the recycled styrene-based resin composition of this embodiment is 5 kJ / m 2 More preferably, it is 7 to 20 kJ / m 2 5kJ / m 2If the hardness is less than this, there is a concern that the material may break during use. In this disclosure, the Charpy impact strength is a value measured in accordance with ISO 179.

[0064] The recycled styrene resin composition of this 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 components (A) to (C) and the mixing ratio of these resins. In this 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 this embodiment, the weight average molecular weight (Mw) of the recycled styrene-based resin composition before the osmium tetroxide treatment is the same as that of the above polymer component, and is preferably 100,000 to 350,000, more preferably 100,000 to 300,000, even 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 having excellent practicality in terms 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 polystyrene standard.

[0066] [Method of producing recycled styrene-based 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 optional components as required. The method for blending, melting, kneading, and granulating the recycled polystyrene resin (A), the rubber-modified polystyrene resin (B), and optional components as required is not particularly limited, and any method commonly used in the production of general styrene resins can be used. For example, the above components are blended (mixed) in a drum tumbler, Henschel mixer, etc., and then melted and kneaded using a Banbury mixer, single screw extruder, twin screw extruder, kneader, etc., sieved through a mesh that passes through a screen mesh, and granulated using a rotary cutter, fan cutter, etc., to obtain a recycled styrene-based resin composition. The resin temperature during melting and kneading is preferably 180 to 240°C. In order to achieve a target resin temperature, it is preferable to set the cylinder temperature of the extruder, etc. to a temperature 10 to 20°C lower than the resin temperature. If the resin temperature is less than 180°C, 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] (Preferable embodiment of the method for producing the recycled styrene-based resin composition) A preferred production method of the present embodiment includes the steps of: (I) preparing a recycled polystyrene-based resin (A) containing a toluene-insoluble portion (1) after osmium tetroxide treatment; and (B) a rubber-modified polystyrene-based resin 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 resin (A) and the rubber-modified polystyrene resin (B). This makes it possible to easily produce a recycled styrene resin composition that reduces the environmental load, suppresses a decrease in mechanical strength, and exhibits excellent appearance. The above steps (I) and (II) will be described in detail below.

[0068] <Process (I)> Step (I) is a preparatory step for preparing a recycled polystyrene-based resin (A) and a rubber-modified polystyrene-based resin (B), which are raw materials for the recycled styrene-based resin composition of the present disclosure. Therefore, the preparation step preferably includes a step (IA) of preparing a recycled polystyrene resin (A) and a step (IB) of preparing a rubber-modified polystyrene resin (B).Therefore, the recycled polystyrene resin (A) and / or the rubber-modified polystyrene resin (B) are used in the step (II) described below depending on the compounds contained therein and the properties thereof. In addition, when the above-mentioned styrene-based resin (C) that does not contain rubber-like polymer particles is used as a raw material for the recycled styrene-based resin composition, the preparation step may further include a step (IC) of preparing the styrene-based resin (C) that does not contain rubber-like polymer particles.

[0069] <<Process (IA)>> As described above, the recycled polystyrene resin (A) of the present embodiment contains the toluene-insoluble matter (1) after the osmium tetroxide treatment and the polymer matrix portion (a1) of the recycled polystyrene resin (A). The recycled polystyrene resin (A) may also contain rubber-like polymer particles (a2). Therefore, the recycled polystyrene resin (A) may be embodied in the following two forms (i) and (ii). (i) The recycled polystyrene resin (A) contains a polymer matrix portion (a1) and a toluene-insoluble portion (1) after osmium tetroxide treatment, and 99% by mass or more of the total amount of the recycled polystyrene resin (A) is occupied by the polymer matrix portion (a1) and the toluene-insoluble portion (1) after osmium tetroxide treatment (for example, polystyrene containing the toluene-insoluble portion (1) after osmium tetroxide treatment, and a styrene copolymer resin containing the toluene-insoluble portion (1) after osmium tetroxide treatment). (ii) The recycled polystyrene resin (A) contains a polymer matrix portion (a1), a rubber-like polymer particle (a2), and a toluene-insoluble portion (1) after osmium tetroxide treatment, and 99% by mass or more of the total amount of the recycled polystyrene resin (A) is accounted for by the polymer matrix portion (a1), the rubber-like polymer particle (a2), and the toluene-insoluble portion (1) after osmium tetroxide treatment (for example, a rubber-modified polystyrene resin containing the toluene-insoluble portion (1) after osmium tetroxide treatment). When the recycled polystyrene resin (A) is in the above embodiment (i), the step (IA) is preferably a step (D1) of determining the content of the toluene-insoluble matter (1) after the osmium tetroxide treatment contained in the recycled polystyrene resin (A) and the weight average molecular weight of the polymer matrix portion (a1). On the other hand, when the recycled polystyrene-based resin (A) is in the above embodiment (ii), the step (IA) is preferably a step (D2) of determining the content of the rubber-like polymer particles (a2) and the content of the toluene-insoluble matter (1) after the osmium tetroxide treatment, both of which are contained in the recycled polystyrene-based resin (A), as well as the weight average molecular weight of the polymer matrix portion (a1). This makes it possible to obtain a recycled styrene-based resin composition that reduces the environmental load, further suppresses the decrease in mechanical strength, and exhibits better appearance and excellent heat creep resistance. In this case, it is preferable that the content of the rubber-like polymer particles (a2) and the content of the toluene-insoluble matter (1) after the osmium tetroxide treatment contained in the recycled polystyrene-based resin (A), as well as the weight average molecular weight of the polymer matrix portion (a1) are each within the above-mentioned ranges.

[0070] <Process (IB)> The step (IB) of preparing the rubber-modified polystyrene-based resin (B) of this embodiment preferably includes 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). This makes it possible to obtain a recycled styrene-based resin composition that reduces the environmental load, further suppresses the decrease in mechanical strength, and exhibits better appearance and excellent heat creep resistance. In this case, it is preferable that the content of the rubber-like polymer particles (b2) contained in the rubber-modified polystyrene-based resin (B) and the weight average molecular weight of the polystyrene-based resin (b1) are each within the above-mentioned ranges.

[0071] <Process (IC)> The step (IC) of preparing the styrene-based resin (C) not containing rubber-like polymer particles in this embodiment preferably includes a step (E2) of selecting the weight average molecular weight of the styrene-based resin (C) not containing rubber-like polymer particles. This reduces the environmental load, suppresses the decrease in mechanical strength, and provides a recycled styrene-based resin composition that has a better appearance and excellent heat creep resistance. In this case, the weight average molecular weight of the styrene-based resin (C) is preferably within the above-mentioned ranges.

[0072] A preferred step (I) of this 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 the osmium tetroxide treatment in the recycled polystyrene-based resin (A), as well as the weight average molecular weight of the polymer matrix portion (a1); 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) 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) not containing the rubber-like polymer particles. This makes it possible to obtain a recycled styrene-based resin composition that reduces the environmental load, further suppresses the decrease in mechanical strength, and exhibits better appearance and excellent heat creep resistance. Moreover, step (I) preferably includes step (III) of removing particulate matter having a predetermined size or larger (for example, a maximum average particle size of 200 μm or larger).

[0073] <Process (II)> The above-mentioned step (II) is a step of melt-kneading the recycled polystyrene-based resin (A) and the rubber-modified polystyrene-based resin (B) prepared in the above-mentioned step (I). As for the conditions for the melt kneading, for example, the above components blended (mixed) in a drum tumbler, Henschel mixer, etc. are preferably melt kneaded using a Banbury mixer, a single screw extruder, a twin screw extruder, a kneader, etc. In addition, the resin temperature during the melt kneading is preferably 180 to 240°C. In this case, "molten" usually means that a part of the recycled polystyrene resin (A) or the rubber-modified polystyrene resin (B) is melted, and does not mean that all of the components in the system are melted. Step (II) of the present embodiment preferably includes a step of determining the amounts of the recycled polystyrene-based resin (A), the rubber-modified polystyrene-based resin (B), and the styrene-based resin (C) that does not contain rubber-like polymer particles, which is optionally blended. Specifically, it is preferable to determine the blending amount so that the resulting recycled styrene-based resin composition satisfies the following (v) to (z). (v) The content of polymer components including the polymer matrix portion (a1) of the recycled polystyrene resin (A), the polystyrene resin (b1) of the rubber-modified polystyrene resin (B), and the styrene resin (C) not containing rubber-like polymer particles is controlled to within a range of 64 to less than 90 mass% based on the total amount of the obtained recycled styrene resin composition. (x) The content of the rubber component including the rubber-like polymer particles (a2) and the rubber-like polymer particles (b2) is controlled to within the range of 9 to less than 30 mass%, preferably 10 to less than 28 mass%, based on the total amount of the obtained recycled styrene-based resin composition. (y) The content of the toluene-insoluble matter (1) after the osmium tetroxide treatment is controlled to within the range of 0.1 to 6 mass %, preferably 1 to 6 mass %, based on the total amount of the resulting recycled styrene-based resin composition. (z) The weight average molecular weight (Mw) of the entire polymer component is controlled to be in the range of 100,000 to 350,000. This makes it possible to obtain a recycled styrene-based resin composition that reduces the environmental load, further suppresses the decrease in mechanical strength, and exhibits better appearance and excellent heat creep resistance.

[0074] Step (II) of this embodiment preferably includes 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 (=dispersoids in a 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 84% integrated diameter in the integral distribution curve of particle diameter, and d16% represents the 16% integrated diameter in the integral distribution curve of particle diameter.) This makes it possible to obtain a recycled styrene-based resin composition that reduces the environmental load, further suppresses the decrease in mechanical strength, and exhibits better appearance and excellent heat creep resistance. Moreover, the step (II) preferably includes a step (III) of removing particulate matter having a predetermined size or larger.

[0075] <Process (III)> The above-mentioned step (III) is a step for removing impurities contained in the recycled polystyrene-based resin (A), and is preferably carried out during the above-mentioned step (I) or the above-mentioned step (II), or after the above-mentioned step (I) or the above-mentioned step (II). This makes it possible to obtain a recycled styrene-based resin composition that reduces the environmental load, further suppresses the decrease in mechanical strength, and exhibits better appearance and excellent heat creep resistance. For example, the above step (III) is a step of separating particulate matter having a size smaller than a predetermined size after blending the recycled polystyrene resin (A), the rubber-modified polystyrene resin (B), and the styrene resin (C) not containing rubber-like polymer particles, which is blended as necessary, preferably after blending the raw materials and while the raw materials are molten. In other words, it can be a step of removing a predetermined amount of toluene-insoluble matter (1) after the osmium tetroxide treatment. Similarly, for example, after the step (D1) or the step (D2), a step (III) of separating particulate matter having a size smaller than a predetermined size may be carried out before the step (II). Specifically, the step (II) may be a step of sieving the molten raw material through one or more devices selected from the group consisting of a filter and a screen mesh, for example, a step of passing the molten raw material through a filter and / or a screen mesh. This can reduce contaminants of a certain size or larger contained in the recycled polystyrene resin (A). The raw material can be melted, for example, by feeding it into an extruder. The passage through the filter and screen mesh can be achieved by providing a polymer filter and / or a screen mesh near the exit or entrance of the extruder.

[0076] The above-mentioned filter is for filtering the polymer components of the molten raw material, and specifically includes a leaf disk filter, a candle filter, and a pack filter. The lower limit of the average pore size of the filter is preferably 10 μm or more, more preferably 30 μm or more, and the upper limit of the average pore size of the filter is preferably 200 μm or less, more preferably 180 μm or less. Examples of the screen mesh include copper mesh and SUS (stainless steel) mesh. The lower limit of the mesh size of the screen mesh is preferably 94 μm or more, more preferably 112 μm or more, even more preferably 134 μm or more, and even more preferably 140 μm or more. The mesh size of the screen mesh is preferably 198 μm or less, more preferably 164 μm or less, even more preferably 132 μm or less, and even more preferably 109 μm or less. The upper limit and the lower limit can be combined in any combination. For example, the screen mesh may be 80 mesh (about 198 μm to 140 μm), 100 mesh (about 164 μm to 134 μm), 120 mesh (132 μm to 112 μm), or 150 mesh (109 μm to 94 μm). By setting the lower limit of the average pore size of the filter or the opening of the screen mesh to the above value, excessive resin pressure is not generated, so that productivity tends to be improved. Similarly, by setting the average pore size of the filter or the opening of the screen mesh to the above value, finer impurities tend to be removed. In this embodiment, the material may be passed through either the filter or the screen mesh, or through both. Furthermore, the material may be passed through only the filter multiple times, or through only the screen mesh multiple times, or through a combination of these.

[0077] In this embodiment, by using the above-mentioned production method, the obtained recycled styrene-based resin composition tends to have the following properties. The particle size distribution (μm) of the DMF insoluble matter in the recycled styrene-based resin composition (=dispersoid in a 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 84% integrated diameter in the integral distribution curve of particle diameter, and d16% represents the 16% integrated diameter in the integral distribution curve of particle diameter.)

[0078] (Particularly preferred method for producing recycled styrene-based resin composition) The method for producing a recycled styrene-based resin composition of the present embodiment includes the steps of: producing a recycled polystyrene-based resin (A) containing a polymer matrix portion (a1), rubber-like polymer particles (a2) and a toluene-insoluble portion (1) after osmium tetroxide treatment; a rubber-modified polystyrene-based resin (B) containing a polymer matrix phase made of a polystyrene-based resin (b1) and a domain phase made of rubber-like polymer particles (b2); A manufacturing method for obtaining a recycled styrene-based resin composition by melt-kneading the above-mentioned mixture with a styrene-based resin (C) used as an optional component, comprising the steps of: A step (D2) of determining the total amount of the rubber-like polymer particles (a2) and the toluene-insoluble matter (1) after the osmium tetroxide treatment contained in the recycled polystyrene-based resin (A), and the weight average molecular weight of the polymer matrix portion (a1); and (E) 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 (F) determining the blending amounts 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): (v) The content of polymer components including the polymer matrix portion (a1) of the recycled polystyrene resin (A), the polystyrene resin (b1) of the rubber-modified polystyrene resin (B), and the styrene resin (C) not containing rubber-like polymer particles is controlled to within a range of 64 to less than 90 mass% based on the total amount of the obtained recycled styrene resin composition. (x) The content of the rubber component including the rubber-like polymer particles (a2) and the rubber-like polymer particles (b2) is controlled to within the range of 9 to less than 30 mass % based on the total amount of the obtained recycled styrene-based resin composition. (y) The content of the toluene-insoluble matter (1) after the osmium tetroxide treatment is controlled to within the range of 1 to 6 mass % based on the total amount of the resulting recycled styrene-based resin composition. (z) The weight average molecular weight (Mw) of the entire polymer component is controlled to be in the range of 100,000 to 350,000. A method for producing a recycled styrene-based resin composition, comprising: a step (G) of adjusting melt-kneading conditions when melt-kneading the above-determined blending amounts so that the particle size distribution (μm) of the DMF-insoluble matter in the recycled styrene-based resin composition (=dispersoid in a composition dispersion obtained by dissolving and dispersing the recycled styrene-based resin composition in N,N-dimethylformamide) satisfies the following formula (1). [Number 4] 0.00<(|d84%-d16%|) / 2<2.00 (1) (d84% represents the 84% integrated diameter in the integral distribution curve of particle diameter, and d16% represents the 16% integrated diameter in the integral distribution curve of particle diameter.) The recycled polystyrene resin (A) is preferably contained in an amount of 30 to 65 mass % relative to the total amount (100 mass %) of the recycled styrene resin composition. This makes it possible to obtain a recycled styrene-based resin composition that reduces the environmental load, further suppresses the decrease in mechanical strength, and exhibits better appearance and excellent heat creep resistance.

[0079] [Molded products] The recycled styrene-based resin composition according to the present disclosure is preferably used for injection blow molding, sheet (including film), injection molding, or extrusion molding.

[0080] [cartridge] As an example of a molded article obtained 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 mounted on an image forming apparatus that forms a multi-color or monochrome image on a recording medium by an electrophotographic method, the cartridge having 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 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 after the osmium tetroxide treatment is more than 0 to 10 mass% based on the entire recycled styrene-based resin composition. The present invention provides a cartridge using a recycled styrene-based resin composition that inhibits deterioration in mechanical strength and chemical resistance, and exhibits excellent appearance and excellent heat creep resistance. Cartridges such as drum cartridges that can be detachably attached to the main body of an image forming apparatus are generally known, and the cartridge contains toner and carrier in a developer container, and is equipped with a mechanism for transporting the toner together with the carrier in the developer container. Meanwhile, a transfer roller that transfers the toner supplied to the photosensitive drum to a sheet is disposed in the main body of the image forming apparatus. Therefore, it was confirmed that heat is generated in the photosensitive drum and the transfer roller, and creep deformation occurs in the cartridge itself or in the mating members (claws, etc.) with other members or in the connecting members. In addition, 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 occurs in that it is difficult for the photosensitive drum to rotate stably. However, it was confirmed that a cartridge with very excellent heat-resistant creep characteristics can be formed by using the recycled styrene-based resin composition of this embodiment (see Examples described later). In addition, in order to reduce the amount of creep deformation, a method can be considered in which a reinforcing material such as metal sheet metal is inserted into the cartridge itself or into the mating parts (such as the claw parts) or connecting parts with other parts. However, by using the recycled styrene-based resin composition of this 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 metal sheet metal.

[0082] The cartridge according to the present embodiment includes a developing unit that develops an electrostatic image formed on the surface of an image carrier into a toner image by using toner, and may be a cartridge that is detachably attached to an image forming apparatus. An example of the cartridge according to the present embodiment is shown below, but is not limited thereto.

[0083] The cartridge of the present embodiment is preferably a cartridge having a toner housing that contains toner and / or a photosensitive drum. In other words, the cartridge of the present embodiment may be an integrated cartridge in which a toner housing part (so-called toner cartridge part) that contains toner and a drum part (so-called drum cartridge part) that contains a photosensitive drum are integrated, or a separate type cartridge in which the toner cartridge (part) and the drum cartridge (part) are separated. Therefore, the cartridge of the present embodiment includes a toner cartridge having a toner housing that contains toner, a drum cartridge having a photosensitive drum, an integrated cartridge having a toner housing part that contains toner and a photosensitive drum, and a separate type cartridge having the toner cartridge and the drum cartridge that is detachable from the toner cartridge.

[0084] Hereinafter, an example of a drum cartridge 10 having a photosensitive drum, a toner cartridge 2 having a toner housing 3 that contains toner, and a separate type cartridge will be described with reference to FIGS. Fig. 1 is a schematic diagram of a so-called cartridge 1, and the cartridge 1 in Fig. 1 shows a separate type cartridge in which a toner cartridge 2 that is detachable from a drum cartridge 10 is attached to the drum cartridge 10. The separate type cartridge is then mounted in the main body housing of an image forming apparatus. In this specification, a cartridge in which the toner cartridge 2 is mounted in the drum cartridge 10 is called a separate type cartridge. In other words, the separate type cartridge includes the drum cartridge 10 and the toner cartridge 2. Moreover, Fig. 2 is a cross-sectional view of the cartridge 1 shown in Fig. 1. And 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 body 7 and a photosensitive drum 5. 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 transport roller 12. The toner cartridge 2 is detachably mounted to the drum cartridge 10 (see FIG. 3). The drum cartridge body 7 is a housing that supports the photosensitive drum 5, the charging means 4, the cleaning roller 8, the transfer roller 11, the transport roller 12, the developing unit 9, and the toner cartridge 2. The drum cartridge body 7 has a positioning protrusion (not shown) for positioning a bearing (not shown). The photosensitive drum 5 is rotatable about a drum shaft that extends in the axial direction. In the following description, the "axial direction" is the direction in which the drum axis of the photosensitive drum 5 extends, and represents the X direction in FIG. 1. The "conveyance direction" is the direction from the conveyance roller 12 toward the transfer roller 11, and represents the Y direction in FIG. 1. The "conveyance direction" is the direction from the lower end of the conveyance roller 12 toward the nip position of a sheet S, such as paper, by the photosensitive drum 5 and the transfer roller 11. The direction perpendicular to the "axial direction" and "conveyance direction" is referred to as the "orthogonal direction," and represents the Z direction in FIG. 1.

[0086] The charging means 4 serves to charge the photosensitive drum 5. Examples of the charging means 4 include a scorotron type or a corotron type, or a charging roller. The cleaning roller 8 serves to clean the photosensitive drum 5. The cleaning roller 8 is rotatable about a cleaning roller shaft extending in the axial direction. The cleaning roller 8 faces the surface of the photosensitive drum 5, and is located downstream in the transport direction of the photosensitive drum 5.

[0087] The transfer roller 11 has a 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 is located on the other side (the lower side in FIG. 1) of the photosensitive drum 5 in the perpendicular direction. The transfer roller 11 is capable of nipping and transporting the sheet S between the transfer roller 11 and the photosensitive drum 5.

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

[0089] The drum cartridge 10 may further include a drum gear as necessary. 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 by a gear train.

[0090] The developing unit 9 is located between the transport roller 12 and the photosensitive drum 5 in the transport direction. The developing unit 9 has 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 axis that extends in the axial direction. The magnetic roller 6 faces the surface of the photosensitive drum 5 and is located upstream of the photosensitive drum 5 in the transport direction. The magnetic roller 6 is spaced from the surface of the photosensitive drum 5. The developing container is a container that contains toner (not shown) and carrier (not shown) to be 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) contained in the toner cartridge 2 (or inside the toner housing 3). The carrier may be a magnetic material other than iron powder.

[0091] The toner cartridge 2 may further include a toner coupling. The toner coupling is located at one end in the axial direction. The toner coupling is a portion through which a driving force is input from the 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, etc., by a gear train.

[0092] In the above embodiment, a separate type cartridge in which the toner cartridge 2 is attached to the drum cartridge 10 has been described, but the cartridge 1 of the present disclosure is not limited to this. For example, the present disclosure is also applicable to a drum cartridge 10 in which the toner cartridge 2 is not attached, and an integrated cartridge in which the toner cartridge 2 or a member housed in the toner cartridge 2 is housed inside the drum cartridge 10. In the above embodiment, a laser printer was given as an example of an image forming apparatus, but this is not limited thereto, and the present disclosure may be applied to other image forming apparatuses such as inkjet printers, copiers, multifunction machines, and the like. EXAMPLES

[0093] The present invention will now be described in detail with reference to examples and comparative examples, but the present invention is not limited to these examples. The resins and molded articles in the examples and comparative examples were analyzed and evaluated as follows.

[0094] [Evaluation of properties of each resin and resin composition] (1) Measurement of weight average molecular weight The weight average molecular weight (Mw) of each of the resins and resin compositions produced in the Examples and Comparative Examples was measured by gel permeation chromatography (GPC) under the following conditions. Measuring equipment: Tosoh HLC-8220 Separation column: Two Tosoh TSK gel Super HZM-H (inner diameter 4.6 mm) connected in series Guard column: Tosoh TSK guard column Super HZ-H Measurement solvent: tetrahydrofuran (THF) Sample concentration: 5 mg of the measurement sample was dissolved in 10 mL of solvent and filtered through a 0.45 μm filter. Injection volume: 10μL Measurement temperature: 40℃ Flow rate: 0.35mL / min Detector: Differential refractometer The calibration curve was created using 11 types of TSK standard polystyrene (F-850, F-450, F-128, F-80, F-40, F-20, F-10, F-4, F-2, F-1, A-5000) manufactured by Tosoh Corporation. The calibration curve was created using a linear approximation equation.

[0095] (2) Measurement of Melt Mass Flow Rate (MFR) The melt mass flow rate (g / 10 min) of each of the resins and resin compositions produced in the Examples and Comparative Examples was measured at 200° C. and a load of 49 N in accordance with ISO1133.

[0096] (3) Measurement of Vicat softening temperature The Vicat softening temperature of each of the resins and resin compositions 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 of the styrene monomer unit, (meth)acrylic acid ester monomer unit, and (meth)acrylic acid monomer unit (NMR measurement) Proton nuclear magnetic resonance ( 1 The resin composition was quantified from the integral ratio of the spectrum measured by a 1 H-NMR measuring device. Sample preparation: 30 mg of resin pellets were dissolved in 0.75 ml of d6-DMSO by heating at 60°C for 6 hours. Measuring equipment: JEOL JNM ECA-500 Measurement conditions: Measurement temperature 25℃, observation nucleus 1H, number of integrations 64, repeat time 11 seconds (NMR Spectral Assignments) The assignments of the spectrum measured in DMSO deuterated solvent are as follows: the peaks at 0.5 to 1.5 ppm are hydrogen atoms of α-methyl groups of methacrylic acid, methyl methacrylate, and six-membered cyclic acid anhydrides, the peaks at 1.6 to 2.1 ppm are hydrogen atoms of methylene groups of the polymer main chain, the peak at 3.5 ppm is hydrogen atoms of carboxylate ester (-COOCH3) of methyl methacrylate, and the peak at 12.4 ppm is hydrogen atoms of carboxylate of methacrylic acid. The peaks at 6.5 to 7.5 ppm are hydrogen atoms of aromatic rings of styrene. Note that the content of six-membered cyclic acid anhydrides in the resin of this embodiment is low, so that quantification is usually difficult 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: Frontier Labs PY-3030D Furnace temperature: 600℃ Boundary temperature: 300℃ GC / MS Equipment: Shimadzu GCMS-GP2020NX Column: Ultra Alloy-5 (Length 30m, film thickness 0.25μm, diameter 0.250mmφ) Column temperature: 50°C for 5 minutes, then increase at 10°C / min. From 100°C, the temperature was increased at 7°C / min and held at 300°C for 10 minutes. Inlet temperature: 300℃ Detector temperature: 300℃ Split ratio: 1 / 300 Carrier gas: Helium Detection method: Mass spectrometer (MSD) Sample amount: 50μg Detection mode: Scan mode or SIM mode In detecting each monomer peak, in order to avoid peak overlap or saturation of peak intensity, pretreatment such as dilution rate of the sample, the column to be used, and detection conditions may be appropriately adjusted.

[0099] (6) Measurement of rubber-like polymer particles The recycled styrene-based resin composition of the examples and the resin composition of the comparative examples described later were stained with osmium tetroxide, and five ultrathin sections with a thickness of 100 nm were prepared, and five bright-field images (magnification 10,000 times) were obtained for each using a transmission electron microscope. The five bright-field images were then 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 having a particle diameter Dri, and the particle diameter Dri is the particle diameter calculated as a circle-equivalent 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 image analysis software ImageJ (manufactured by the National Institutes of Health, USA). The acquired image was binarized using Otsu's method, and white areas other than the rubber-like polymer particles (corresponding to the polymer matrix phase) were filled in. Adjacent rubber-like polymer particles were divided by Watershed processing, and the area of ​​the rubber-like polymer particles was calculated and converted into a circle-equivalent diameter. A number-based histogram and average value were derived from the obtained group of circle-equivalent diameter values. The following equipment was used. Ultramicrotome: UC7 / Leica Transmission electron microscope: HT7700 / Hitachi High-Technologies

[0100] (8) Charpy impact strength measurement The test specimens used to measure the Charpy impact strength were strips of specified dimensions cut out from the central parallel part of a 1A type dumbbell prepared by the method described in the "ISO dumbbell test specimen manufacturing method" section below. The test was performed in accordance with ISO 179 to measure the Charpy impact strength (kJ / m 2 ) was measured with a notch.

[0101] (9) Measurement of tensile yield stress The test pieces used for measuring the tensile yield stress were 1A-type dumbbells prepared by the method described in the section "Method of manufacturing ISO dumbbell test pieces" below using the resin compositions prepared in the Examples and Comparative Examples. The tensile yield stress (MPa) of the test pieces was measured in accordance with ISO527-1.

[0102] (10) Measurement of nominal tensile breaking strain From each of the resin compositions produced in the Examples and Comparative Examples, injection-molded pieces were prepared at 220° C. in accordance with JIS K 7152, and the nominal tensile strain at break (%) was measured in accordance with JIS K 7161 and ISO527-1.

[0103] (11) Measurement of bending modulus Each of the various resin compositions produced in the Examples and Comparative Examples was injection molded into an ISO type 1A dumbbell test piece, and the flexural modulus (MPa) was measured in accordance with ISO178 using a strip of specified dimensions cut out from the central parallel part of the dumbbell.

[0104] (12) Measurement of deflection temperature under load From the various resin compositions produced in the Examples and Comparative Examples, ISO type 1A dumbbell test pieces were injection molded, and strips of specified dimensions were cut out from the central parallel part of the dumbbell to measure the deflection temperature under load (unit: °C) at a load of 1.8 MPa in accordance with ISO 75-1 and 75-2. The deflection temperature under load was measured using "AUTO HDT Tester 6A-2V" manufactured by Toyo Seiki Co., Ltd.

[0105] (13) Measurement of chemical resistance (property retention rate) To evaluate the chemical resistance of the various resin compositions produced in the Examples and Comparative Examples, a specified grease (Molycoat EM-50LP: DuPont Toray Specialty Materials Co., Ltd.) was applied to the central parallel part of an ISO type 1A dumbbell test piece, and aging treatment was performed for 168 hours in a hot air circulation oven at 60°C. After wiping off the grease with a cloth, the appearance was confirmed, the tensile breaking strain was measured, and the retention rate (%) was calculated by comparing with the initial value. Chemical resistance (property retention rate) (%) = (tensile breaking strain of sample after aging for 168 hours with grease applied) ÷ (tensile breaking strain of sample without aging for 168 hours with no grease applied)

[0106] (14) Measurement of heat-resistant creep properties A three-point load bending creep test was conducted in accordance with ISO899-2 on a rectangular strip of the specified dimensions cut from the central parallel part of a 1A-type dumbbell test piece. The ambient temperature was 60°C, the load was 29.4 N, and the strain (mm) after a certain period of time (100 hours) was used to evaluate the properties.

[0107] (15) Appearance A three-tiered plate with dimensions of 120 x 50 mm and thicknesses of 2.5 mm, 2.0 mm, and 1.0 mm was molded using an injection molding machine. The 2.0 mm-thick flat area (40 x 50 mm) in the center of the plate was used to observe the presence of black spots and measure the 60° gloss. The black spots were classified by size according to the impurity measurement chart (JIS P 8208) and the number of spots was counted. All the black spots observed were 0.1 mm 2 If it is less than this, it is ok, if it is more than 0.1 to 0.5 mm 2 20 or less and between 0.5 and 0.7 mm 2 If there were two or less of these, the rating was △, otherwise it was marked as ×. The gloss level was measured using a gloss meter GM26D (Murakami Color Research Laboratory Co., Ltd.) and the 60° specular gloss was measured in accordance with JIS Z 8741. A gloss level of 35 or less was rated as △, and a gloss level of 36 or more was rated as ○ (pass).

[0108] (16) Laser diffraction measurement 20 mg of the recycled styrene resin composition of the embodiment and the resin composition of the comparative example and 20 mL of N,N-dimethylformamide were placed in a polypropylene disposable cup, and dissolved and dispersed by ultrasonic vibration for 15 minutes. While vibrating, a part of the cloudy liquid of the sample was collected and placed in a measurement cell, and while stirring with a rotor, the particle size (d84%, d50%, d16%) and integral distribution curve of the dispersed matter of the recycled styrene resin composition or the N,N-dimethylformamide solution containing the resin composition were obtained using a laser diffraction particle size measuring device (LA-960V2, manufactured by Horiba, Ltd.). 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, a volume-based particle size distribution was adopted. For example, the volume-based particle size distribution (d 84 %-d 16 %) is 1.18, and the average particle diameter d 50 On the other hand, the particle size distribution based on the number of particles (d 84 %-d 16 %) is 0.90, and the average particle diameter d 50 % was 1.2 μm. In the other examples as well, the average particle size was smaller and the distribution tended to be narrower on the number basis.

[0109] (17) Measurement of weld strength retention (flexural strength) Using the recycled styrene-based resin composition obtained in the examples and comparative examples, a mold was attached to the mold in which the molten resin of the recycled styrene-based resin composition flows from both ends of the length direction of a shape of 125 mm in length, 13 mm in width, and 3.2 mm in thickness, and a weld is formed in 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) with an injection molding machine (PS40E manufactured by Nissei Plastic Industrial Co., Ltd.) to obtain a test piece. The molded test piece was subjected to a tensile test according to the method in accordance with ISO 527, except that the chuck distance was 50 mm and the tensile speed was 1.5 mm / min, and the tensile strength was calculated from the following formula. The measured value was the average value of N = 5. Weld strength retention rate (%) = (flexural strength with weld) ÷ (flexural strength without weld) × 100

[0110] [Materials used in the 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] "Method for producing recycled styrene-based resin composition of Examples 1 to 20" The raw materials described in the above column "Raw materials used in the Examples and Comparative Examples" were prepared. Specifically, the content of rubber-like polymer particles (a2) contained in the recycled polystyrene resins (A1) to (A8), the content of toluene-insoluble matter (1) (=contaminants) after the osmium tetroxide treatment, and the weight-average molecular weight of the polymer matrix portion (a1) were measured before melt-kneading. In addition, 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. In each example, the raw materials were prepared according to the above [Raw materials used in the examples and comparative examples] column and the following Tables 2-1 to 2-3 so that the molecular weight, the content of the rubber component, the content of the impurities (the content of the 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 were predetermined values, and then the measured raw materials were blended in a drum tumbler and melt-kneaded in a twin-screw extruder (TEM-26SS manufactured by Toshiba Machine Co., Ltd.) at a cylinder setting temperature of 220 ° C. and a screw rotation speed of 200 rpm. The molten resin passed through a screen mesh installed upstream of the breaker plate between the tip of the extruder screw and the die, and was then drawn out as a molten strand from the die. The molten strand was cooled with water and cut with a rotary cutter to obtain pellet-shaped recycled styrene-based resin compositions of Examples 1 to 20. Then, 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 the above melt kneading, the particle size distribution based on volume (d 84 %-d 16 If necessary, the melt was passed through a screen mesh to ensure that the % melt content was less than 2.

[0117] "Methods for producing resin compositions of Comparative Examples 1 to 6 and Reference Examples 1 to 4" After preparing the raw materials according to the above-mentioned column "Raw materials used in the Examples and Comparative Examples" and the following Table 1, the weighed raw materials were compounded in a drum tumbler, melt-kneaded in a twin-screw extruder (TEM-26SS manufactured by Toshiba Machine Co., Ltd.) at a cylinder set temperature of 220°C and a screw rotation speed of 200 rpm, and extruded as molten strands. The molten strands were cooled with water and cut with a rotary cutter to obtain pellet-shaped resin compositions of Comparative Examples 1 to 6 and Reference Examples 1 to 4. The physical properties of the obtained resin compositions of Comparative Examples 1 to 6 and Reference Examples 1 to 4 were measured and evaluated according to the measurement methods described above. The results are shown in Tables 2-3 and 2-4.

[0118] [Table 2-1]

[0119] [Table 2-2]

[0120] [Table 2-3]

[0121] [Table 2-4]

[0122] "Preparation and Evaluation of Cartridges of Examples 21 to 26" A cartridge housing (cartridge body) was produced using the recycled styrene resin composition produced in the above examples. Specifically, the cartridge housing has a box shape (dimensions: length: 260 mm x depth: 80 mm x height: 80 mm) with ribs set in a lattice pattern, and was produced by molding the recycled styrene resin composition produced in the examples shown in Table 3 using a three-plate mold with a cold runner with two pin gates. The obtained cartridge housing was subjected to practical creep evaluation under the following conditions. The results are shown in Table 3. <Evaluation of practical creep properties> The positioning pin inside the cartridge housing is fixed to a jig. Next, a weight of 4.6 kg (a steel weight with a diameter of 50 mm and a height of 300 mm) is applied to the center of the cartridge housing in the longitudinal direction. The cartridge housing is then placed in an oven at 60°C for 100 hours, after which the deformation (mm) of the center of the cartridge housing is measured. If the deformation of the center of the cartridge housing is within 0.5 mm, it is considered to pass (○), and if the deformation exceeds 0.5 mm, it is considered to fail (×).

[0123] "Cartridge of Comparative Example 7" A cartridge housing was produced using the resin composition in the same manner as in the above-mentioned Examples 21 to 26. 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 case 4. Charging means 5 Photoconductor drum 6 Magnetic Roller 7 Drum cartridge body 8 Cleaning roller 9 Development Unit 10 Drum Cartridge 11 Transfer roller 12 Transport 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 polystyrene resin (A) contains a polymer matrix portion (a1) and 55 to less than 97.9 mass% of a polymer component including the polystyrene resin (b1), 2.1 to 35 mass% of a rubber component including the rubber-like polymer particles (b2), and more than 0 to 10 mass% of a toluene-insoluble matter after osmium tetroxide treatment (1) obtained by treating the recycled polystyrene resin (A) with osmium tetroxide, The recycled styrene-based resin composition is dissolved and dispersed in N,N-dimethylformamide, and the dispersed matter in the dispersion of the recycled styrene-based resin composition is represented by the following formula (1): [Equation 1] 0<(|d ８４％ -d １６％ |) / 2<2 (1) (In the above formula, d ８４％ represents the integrated 84% diameter in an integral distribution curve of the particle diameter of the dispersoid measured by a laser diffraction method, and d １６％ represents an integrated 16% diameter in an integral distribution curve of the particle diameter of the dispersoid measured by a laser diffraction method; 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, A recycled styrene-based resin composition having a weld strength retention rate (%) represented by the following formula of more than 70% and not more than 90%. Weld strength retention rate (%) = (flexural strength with weld) ÷ (flexural strength without weld) × 100

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

3. The polymer component is composed only of the polymer matrix portion (a1) of the recycled polystyrene resin (A), the polystyrene resin (b1), the styrene resin (C) and an additive component, and the styrene resin (C) is a polymer composed only of styrene monomer units, or a polymer composed only of styrene monomer units and unsaturated carboxylic acid monomer units, and the monomers constituting the styrene monomer units are selected from styrene, α-methylstyrene, α-methyl p-methylstyrene, ο-methylstyrene, m-methylstyrene, p-methylstyrene, vinyltoluene, ethylstyrene, isobutylstyrene, t-butylstyrene, bromostyrene and indene, and the monomers constituting the unsaturated carboxylic acid monomer units are selected from (meth)acrylic acid monomers and (meth)acrylic acid ester monomers. The recycled styrene resin composition according to claim 2.

4. 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 1.1 to 3.2 μm.

5. 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.

6. 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.

7. 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.

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

9. 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 the recycled styrene-based resin composition according to claim 1, which comprises: a recycled polystyrene-based resin (A) containing a toluene-insoluble matter (1) after the osmium tetroxide treatment; and a rubber-modified polystyrene-based resin (B) containing a rubber-like polymer particle (b2) constituting the domain phase and a polystyrene-based resin (b1) constituting the polymer matrix phase, and the toluene-insoluble matter (1) after the osmium tetroxide treatment is more than 0 to 10 mass% of the entire recycled styrene-based resin composition.

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