Regenerated ABS resin composition

Abstract

Provided is a regenerated ABS resin composition having excellent strength, toughness, and impact resistance. The regenerated ABS resin composition contains a recycled ABS resin (a) and a hydrogenated block copolymer (x), and the hydrogenated block copolymer (x) is a block copolymer having a polymer block S mainly composed of a vinyl aromatic monomer unit and a polymer block B mainly composed of a conjugated diene monomer unit. 30 mol% or more of the conjugated diene part constituting the hydrogenated block copolymer (x) is hydrogenated, and the hydrogenated block copolymer (x) contains 30-100 mass% of a modified hydrogenated block copolymer (b *) in which the content of the conjugated diene part in the modified hydrogenated block copolymer (b *) is 30-100 mass%, and the content of the conjugated diene part in the modified hydrogenated block copolymer (b *) is 30-100 mass%. At least one heteroatom-containing functional group is chemically bonded to a polymer graft chain, a polymer terminal, or a coupling agent residue, and the mass ratio of the recycled ABS resin (a) to the hydrogenated block copolymer (x) is (a) / (x) = 99 / 1 to 80 / 20.

Description

Technical Field

[0001] The present invention relates to a recycled ABS resin composition. Background Art

[0002] Vinyl aromatic resins, such as polystyrene resins and ABS resins (acrylonitrile / butadiene / styrene copolymers), generally exhibit excellent moldability, rigidity, and impact resistance. Furthermore, they are low in cost, have a low specific gravity, and are economical. Therefore, they are widely used in various fields, such as automotive interior materials, housings for home appliances and office automation (OA) applications, and daily necessities.

[0003] Among the above vinyl aromatic resins, ABS resins, which have an excellent balance among impact resistance, rigidity, and chemical resistance, are widely used as materials for main components of various durable consumer products, mainly injection-molded products, such as home appliances, sundries, and automotive parts.

[0004] In recent years, opportunities for recycling towards a circular economy have been increasing to reduce the impact on the global environment. Recycling is also being promoted for home appliances, with the Home Appliance Recycling Act in Japan specifically promoting material recycling for four categories: air conditioners, televisions, refrigerators, and washing machines.

[0005] The four types of home appliances mentioned above use large amounts of ABS resin, and a significant amount of this resin can be recovered from their waste. Furthermore, ABS resin is also used extensively in automotive interior components, and is recycled after vehicles are scrapped.

[0006] There are three main types of plastic waste recycling: thermal recycling, which involves burning the waste to recover heat energy; chemical recycling, which involves chemically decomposing the waste and converting it into oil or monomeric raw materials for recovery; and material recycling, which involves crushing the waste, remelting it, and processing it into molding materials for reuse in various molded products. Of these recycling methods, material recycling has attracted attention due to its reduced environmental impact and efficient resource utilization, leading to research and development efforts by various companies.

[0007] Resin-molded articles commonly used in various industrial products, including home appliances and automobiles, incorporate a variety of resin materials, including polyolefin resins like polypropylene, ABS resins, and polyamide resins. When these industrial products become waste, they produce resin residues, also known as crushing residues, a mixture of various resins. These residues are often a mixture of dissimilar resins, and due to quality and mechanical properties, they cannot be used directly as original resin-molded parts.

[0008] On the other hand, due to the remarkable technological innovations in material recycling in recent years, it is now possible to screen out polyolefin resins such as polypropylene with a low specific gravity and polystyrene and ABS resins with a specific gravity slightly greater than 1 through gravity classification. Furthermore, polystyrene and ABS resins can be screened out through electrostatic classification utilizing polarity differences and recovered as recycled ABS resin.

[0009] However, recycled ABS resins that undergo such screening and recycling typically deteriorate over time. Furthermore, since it's practically impossible to achieve 100% purity through screening and recycling, small amounts of incompatible foreign resins such as polystyrene and polyamide may be mixed into the recycled ABS resin. Furthermore, coatings and plating applied to the ABS resin substrate are difficult to completely remove, potentially leading to small amounts of foreign matter being incorporated into the resin. Consequently, recycled ABS resins, as molding materials for durable consumer goods, exhibit significantly inferior quality and mechanical properties compared to virgin ABS resins, forcing them to be recycled thermally. This presents numerous challenges in material recycling.

[0010] Regarding the above-mentioned problems, particularly the problem of deterioration in physical properties of recycled ABS resins, studies have been conducted to try to improve them (see, for example, Patent Documents 1 and 2).

[0011] Prior art literature

[0012] Patent Literature

[0013] Patent Document 1: Japanese Patent Application Laid-Open No. 2003-231119

[0014] Patent Document 2: Japanese Patent Application Laid-Open No. 2011-126995 Summary of the Invention

[0015] Problems to be solved by the invention

[0016] However, since ABS resins are copolymerized with acrylonitrile as a monomer component, they have high polarity and low compatibility with common olefin-based elastomers and styrene-based elastomers. Therefore, it is difficult to modify recycled ABS resins with these elastomers, resulting in a problem in achieving mechanical properties suitable for practical use.

[0017] Therefore, an object of the present invention is to provide a recycled ABS resin composition having excellent strength, toughness, and impact resistance, which enables recycled ABS resin, which has been difficult to recycle, to be used in applications where virgin ABS resin is used, as a recycled ABS resin composition with high product value.

[0018] Means for solving problems

[0019] The present inventors have conducted intensive research to address the conventional problems associated with recycled ABS resins. As a result, they have discovered that the aforementioned conventional problems can be addressed by blending a hydrogenated block copolymer having a specific structure into recycled ABS resins, leading to the completion of the present invention.

[0020] That is, the present invention is as follows. [1]

[0022] A recycled ABS resin composition comprising a recycled ABS resin (a) and a hydrogenated block copolymer (x), wherein:

[0023] The hydrogenated block copolymer (x) is a block copolymer having at least one polymer block S mainly composed of vinyl aromatic monomer units and at least one polymer block B mainly composed of conjugated diene monomer units.

[0024] At least 30 mol% of the conjugated diene portion constituting the hydrogenated block copolymer (x) is hydrogenated.

[0025] Regarding the above-mentioned hydrogenated block copolymer (x),

[0026] The hydrogenated block copolymer (x) contains 30% by mass or more and 100% by mass or less of a modified hydrogenated block copolymer (b*), wherein the modified hydrogenated block copolymer (b*) has at least one molecule of a functional group containing a heteroatom chemically bonded to a polymer graft chain, a polymer terminal, or a coupling agent residue.

[0027] The mass ratio of the recycled ABS-based resin (a) to the hydrogenated block copolymer (x) is (a) / (x) = 99 / 1 to 80 / 20. [2]

[0029] The recycled ABS resin composition as described in [1] above, wherein

[0030] Further containing virgin ABS resin (a*),

[0031] The mass ratio of the recycled ABS resin (a) to the virgin ABS resin (a*) is (a) / (a*)=100 / 0 to 20 / 80. [3]

[0033] The recycled ABS resin composition as described in [1] or [2] above, wherein the hydrogenated block copolymer (x) has a vinyl aromatic monomer unit content of 15% to 50% by mass and a conjugated diene monomer unit content of 85% to 50% by mass. [4]

[0035] The recycled ABS resin composition according to any one of the above-mentioned [1] to [3], wherein the modified hydrogenated block copolymer (b*) has a functional group on at least one polymer terminal and / or a coupling agent residue. [5]

[0037] The recycled ABS resin composition as described in [4] above, wherein the modified hydrogenated block copolymer (b*) has a functional group at at least one polymer terminal, and the functional group is any one selected from the group consisting of a primary amino group, a secondary amino group, and an epoxy group. [6]

[0039] The recycled ABS resin composition according to any one of [1] to [5] above, wherein the recycled ABS resin (a) is a reclaimed product from consumer waste and / or industrial waste. [7]

[0041] The recycled ABS resin composition according to any one of [1] to [5] above, wherein the recycled ABS resin (a) is a recyclate from a molded article, wherein the molded article is a molded article constituting a housing or a mechanism part of any one selected from the group consisting of home appliances, information equipment, communication equipment, and automobiles.

[0042] Effects of the Invention

[0043] According to the present invention, a recycled ABS-based resin composition having excellent strength, toughness, and impact resistance can be provided. DETAILED DESCRIPTION

[0044] A specific embodiment of the present invention (hereinafter referred to as "this embodiment") will be described in detail below.

[0045] It should be noted that the following embodiments are examples for explaining the present invention and are not intended to limit the present invention to the following contents. The present invention can be implemented with various modifications within the scope of the gist of the invention.

[0046] [Recycled ABS resin composition]

[0047] The recycled ABS resin composition comprises a recycled ABS resin (a) and a hydrogenated block copolymer (x), wherein:

[0048] The hydrogenated block copolymer (x) is a block copolymer having at least one polymer block S mainly composed of vinyl aromatic monomer units and at least one polymer block B mainly composed of conjugated diene monomer units.

[0049] At least 30 mol% of the conjugated diene portion constituting the hydrogenated block copolymer (x) is hydrogenated.

[0050] Regarding the above-mentioned hydrogenated block copolymer (x),

[0051] The hydrogenated block copolymer (x) contains 30% by mass or more and 100% by mass or less of a modified hydrogenated block copolymer (b*), wherein the modified hydrogenated block copolymer (b*) has at least one molecule of a functional group containing a heteroatom chemically bonded to a polymer graft chain, a polymer terminal, or a coupling agent residue.

[0052] The mass ratio of the recycled ABS-based resin (a) to the hydrogenated block copolymer (x) is (a) / (x) = 99 / 1 to 80 / 20.

[0053] The mass ratio of the recycled ABS resin (a) to the hydrogenated block copolymer (b) is preferably in the range of (a) / (b) = 98 / 2 to 85 / 15, more preferably in the range of (a) / (b) = 97 / 3 to 88 / 12.

[0054] The aforementioned structure enables the recycled ABS resin composition of this embodiment to exhibit excellent strength, toughness, and impact resistance. Furthermore, by modifying the recycled ABS resin (a) with a specific hydrogenated block copolymer (x), its mechanical properties are comparable to those of virgin ABS resin, enabling its effective use as an industrial component. This results in the efficient utilization of petrochemical resources, contributing to the circular economy from the perspective of global environmental protection.

[0055] The recycled ABS resin composition of this embodiment is mainly composed of ABS (acrylonitrile / butadiene / styrene) resin. Here, "mainly composed of ABS resin" means that the content of ABS resin in the recycled ABS resin composition of this embodiment is 80% by mass or more.

[0056] In this specification, when the term "mainly" is used to describe the proportion of a monomer unit in a polymer, it means that the content of the specified monomer unit is 60% by mass or more, preferably 80% by mass or more, and more preferably 90% by mass or more.

[0057] (Recycled ABS resin (a))

[0058] The recycled ABS resin (a) constituting the regenerated ABS resin composition of the present embodiment is preferably, for example, recycled material from consumer waste and / or industrial waste, or recycled material from molded articles (molded articles constituting housings or mechanism parts of any one selected from the group consisting of household appliances, information equipment, communication equipment, and automobiles), and includes ABS resins recovered from these various used products.

[0059] The recycled ABS resin (a) is defined as containing at least 1% by mass or more of unintentional impurities derived from used products, in addition to intended additives such as stabilizers.

[0060] Recycling technology has advanced significantly in recent years. In addition to conventional gravity separation methods, which utilize differences in specific gravity by immersing the resin in water, electrostatic separation methods, which utilize differences in electrical properties, have been established. This technology, for example, allows for precise separation of the low-polarity polystyrene resin from the somewhat high-polarity ABS resin, despite the fact that the specific gravity of ABS resin (1.05-1.08) is relatively close to that of polystyrene resin (1.04-1.05).

[0061] After crushing and pulverizing the recovered product, the purity of the ABS resin in the recycled ABS resin (a) used in this embodiment is preferably adjusted to 80% by mass or higher, more preferably 85% by mass or higher, further preferably 90% by mass or higher, and even more preferably 95% by mass or higher, by applying the above-mentioned specific gravity classification method and electrostatic classification method.

[0062] While it is technically possible to increase the purity of the ABS resin in the recycled ABS resin (a), at the expense of time and cost, economic efficiency is also important in order to provide it as a practical industrial product. Therefore, it is preferable to arbitrarily set the purity of the ABS resin in the recycled ABS resin (a) based on the properties and quality required for the recycling target.

[0063] Furthermore, by including an unused virgin ABS resin (a*) described below in addition to the recycled ABS resin (a) in the recycled ABS resin composition of this embodiment, the low purity of the ABS resin shown in the recycled ABS resin (a) can be compensated, and the mechanical properties that have decreased due to aging can also be compensated.

[0064] The content of foreign resins and foreign matter in the recycled ABS resin (a) is preferably 20% by mass or less, more preferably 15% by mass or less, further preferably 10% by mass or less, and even more preferably 5% by mass or less.

[0065] The types and contents of these foreign resins and foreign materials tend to be affected by the products being recycled.

[0066] When the recycled ABS resin (a) is derived from automobiles, for example, it tends to contain trace amounts of polyamide resins, polypropylene resins, plating materials, coatings, etc. It also tends to contain inorganic substances such as talc and glass fiber.

[0067] On the other hand, when the recycled ABS-based resin (a) is a component derived from home appliances, it tends to contain additives such as flame retardants in addition to foreign resins such as polystyrene resin and polycarbonate / ABS resin alloy.

[0068] These are merely examples, and the foreign resins and foreign matter are not particularly limited.

[0069] In addition, AES-based resins obtained by using ethylene-based rubber instead of butadiene rubber for the purpose of improving light resistance, and ASA-based resins obtained by using acrylate-based rubber instead of butadiene rubber are also included in the recycled ABS-based resin (a) constituting the recycled ABS-based resin composition of this embodiment, and can be appropriately used as constituent materials of the recycled ABS-based resin composition of this embodiment.

[0070] Furthermore, alloy materials of ABS resin, polycarbonate resin, and acrylic resin are also included in the recycled ABS resin (a) constituting the recycled ABS resin composition of this embodiment and can be suitably used as a constituent material of the recycled ABS resin composition of this embodiment.

[0071] (Virgin ABS resin (a*))

[0072] The recycled ABS resin composition of the present embodiment may further contain a virgin ABS resin (a*) in addition to the recycled ABS resin (a) without departing from the gist of the present invention.

[0073] Virgin ABS resin (a*) is defined as a material that has never been used as a molded article and consists solely of ABS resin as a base polymer and stabilizers or additives intended to impart functionality. Impurities derived from the manufacturing process, such as residual solvents and emulsifiers, have been removed, resulting in a purity of 100% by mass.

[0074] The content of the virgin ABS resin in the recycled ABS resin composition of the present embodiment is preferably (a) / (a*) = 100 / 0 to 20 / 80, as measured by the mass ratio of the recycled ABS resin (a) / virgin ABS resin (a*). However, in view of the scope of the present invention, the proportion of the recycled ABS resin (a) is preferably high, preferably close to 100% by mass. Specifically, (a) / (a*) is more preferably 100 / 0 to 50 / 50, and even more preferably 100 / 0 to 70 / 30.

[0075] The monomer composition ratio (acrylonitrile / butadiene / styrene composition ratio) of the recycled ABS resin (a) and the virgin ABS resin (a*) may be the same or different. Since recycled ABS resins generally experience degradation of mechanical properties due to aging, the melt flow rate of the virgin ABS resin (a*) is preferably lower than that of the recycled ABS resin.

[0076] The virgin ABS resin (a*) includes all so-called ABS resins that have been circulated on the market from the past to the present, and is not particularly limited to manufacturers or brands.

[0077] Examples of commercially available ABS-based resins include, but are not limited to, “Cevian (registered trademark)” manufactured by Daicel, “Toyolac (registered trademark)” manufactured by Toray, “Kralastic (registered trademark)” manufactured by Nippon A&L Inc., “Techno-ABS (registered trademark)” manufactured by Techno-UMG, “Polylac (registered trademark)” manufactured by Chi Mei Industries, and “Terluran (registered trademark)” manufactured by Ineos.

[0078] Virgin ABS resin (a*) may be a pure polymer that does not contain functional auxiliary materials such as colorants, lubricants, fillers, and flame retardants, or a so-called composite grade mixed with functional auxiliary materials. Furthermore, it may also be a functional ABS resin that has been imparted with improved heat resistance by copolymerizing comonomers such as maleimide, or an ABS resin obtained by copolymerizing (meth)acrylic monomers, etc., all of which are included in the virgin ABS resin (a*).

[0079] Furthermore, the above-mentioned AES-based resin using ethylene-based rubber and ASA-based resin using acrylic ester-based rubber are also included in the virgin ABS-based resin (a*).

[0080] In addition, alloy materials of ABS resin, polycarbonate resin, and acrylic resin are also included in the virgin ABS resin (a*).

[0081] Regarding the method for producing ABS resin, any known method can be applied. ABS resin may be either one produced by emulsion polymerization or one produced by solution polymerization.

[0082] (Hydrogenated block copolymer (x))

[0083] The recycled ABS-based resin composition of the present embodiment contains a hydrogenated block copolymer (x).

[0084] The hydrogenated block copolymer (x) is a block copolymer comprising at least one polymer block S mainly composed of vinyl aromatic monomer units and at least one polymer block B mainly composed of conjugated diene monomer units, wherein at least 30 mol% of the conjugated diene portion is hydrogenated.

[0085] The hydrogenated block copolymer (x) contains 30% by mass or more and 100% by mass or less of a modified hydrogenated block copolymer (b*) in the hydrogenated block copolymer (x), wherein at least one molecule of a functional group containing a heteroatom is chemically bonded to a polymer graft chain, a polymer terminal, or a coupling agent residue in the modified hydrogenated block copolymer (b*).

[0086] That is, the hydrogenated block copolymer (x) used in the recycled ABS resin composition of this embodiment contains 30% by mass or more of the modified hydrogenated block copolymer (b*). When the content of the modified hydrogenated block copolymer (b*) is 100% by mass, the hydrogenated block copolymer (x) and the modified hydrogenated block copolymer (b*) are identical. When the content of the modified hydrogenated block copolymer (b*) is less than 100% by mass, the hydrogenated block copolymer (x) contains the unmodified hydrogenated block copolymer (b).

[0087] The hydrogenated block copolymer (x) comprises a polymer block S mainly composed of vinyl aromatic monomer units and a polymer block B mainly composed of conjugated diene monomer units, and the number of either polymer block or both blocks may be two or more.

[0088] In addition, in the hydrogenated block copolymer (x), from the viewpoint of the balance between the rigidity and impact strength of the molded article of the regenerated ABS resin composition of the present embodiment, the content of the vinyl aromatic monomer unit is preferably 15 to 50% by mass, and the content of the conjugated diene monomer unit is preferably 50 to 85% by mass.

[0089] More preferably, the content of the vinyl aromatic monomer unit is 25 to 50% by mass, and the content of the conjugated diene monomer unit is 50 to 75% by mass.

[0090] More preferably, the content of the vinyl aromatic monomer unit is 28 to 42% by mass, and the content of the conjugated diene monomer unit is 58 to 72% by mass.

[0091] In the hydrogenated block copolymer (x), 30 mol% or more of the conjugated diene portion is hydrogenated.

[0092] By hydrogenating the conjugated diene moiety, it converts to an olefin structure, significantly improving thermal stability during processing. By setting the hydrogenation rate of the conjugated diene moiety of the hydrogenated block copolymer (x) to 30 mol% or higher, a recycled ABS resin composition with an excellent balance of mechanical properties tends to be obtained.

[0093] The hydrogenation rate can be quantified by a known analytical method, and for example, infrared absorption spectroscopy, 1H-NMR, etc. can be appropriately used.

[0094] In the hydrogenated block copolymer (x), the hydrogenation rate of the conjugated diene portion is 30 mol% or more, preferably 40 mol% or more, more preferably 50 mol% or more, further preferably 60 mol% or more, and even more preferably 70 mol% or more.

[0095] The upper limit of the hydrogenation rate is not particularly limited, but is preferably 100 mol% or less.

[0096] When the hydrogenation rate of the conjugated diene portion of the hydrogenated block copolymer (x) is 30 mol% or more, the thermal stability during processing is significantly improved, and a recycled ABS-based resin composition having preferred mechanical properties tends to be obtained.

[0097] The hydrogenation rate of the conjugated diene portion of the hydrogenated block copolymer (x) can be controlled within the above-mentioned numerical range by adjusting the type and amount of the hydrogenation catalyst, the amount of hydrogen supplied in the hydrogenation step, and the hydrogenation step time.

[0098] From the perspective of the mechanical properties of the recycled ABS resin composition of this embodiment, the polymer block S mainly composed of vinyl aromatic monomer units constituting the hydrogenated block copolymer (x) preferably contains 90% by mass or more of vinyl aromatic monomer units.

[0099] The polymer block mainly composed of conjugated diene monomer units constituting the hydrogenated block copolymer (x) may be a conjugated diene polymer block composed solely of conjugated diene monomer units, or may be a copolymer block of conjugated diene monomer units and vinyl aromatic monomer units. In the case of a copolymer block, various copolymer block structures may be employed, such as a uniform random structure and a tapered structure (in which the monomer composition ratio varies along the chain).

[0100] The hydrogenated block copolymer (x) may be a combination of two or more block copolymers having different average molecular weights, or a combination of two or more block copolymers having different copolymerization ratios of vinyl aromatic monomer units to conjugated diene monomer units.

[0101] The hydrogenated block copolymer (x) may contain other polymerizable monomer units in addition to the vinyl aromatic monomer unit and the conjugated diene monomer unit, if necessary.

[0102] The vinyl aromatic monomer units constituting the hydrogenated block copolymer (x) can be formed using a vinyl aromatic compound.

[0103] The vinyl aromatic compound may be any compound as long as it has an aromatic ring and a vinyl group in the molecule. Examples thereof include, but are not limited to, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o-ethylstyrene, p-ethylstyrene, p-tert-butylstyrene, 2,4-dimethylstyrene, 1,3-dimethylstyrene, α-methylstyrene, α-methyl-p-methylstyrene, vinylnaphthalene, vinylanthracene, and 1,1-diphenylethylene.

[0104] These vinyl aromatic compounds may be used alone or in combination of two or more. Among these, styrene is preferred from the viewpoint of industrial efficiency and economic efficiency.

[0105] The conjugated diene monomer units constituting the hydrogenated block copolymer (x) can be formed using a conjugated diene compound.

[0106] The conjugated diene compound may be any diene having a pair of conjugated double bonds, and examples thereof include, but are not limited to, 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, and 1,3-hexadiene.

[0107] These conjugated diene compounds may be used alone or in combination of two or more.

[0108] Among these, from the viewpoint of industrial efficiency and economic efficiency, 1,3-butadiene and isoprene are preferred, and 1,3-butadiene is more preferred.

[0109] In the hydrogenated block copolymer (x), the mass ratio of the vinyl aromatic monomer unit to the conjugated diene monomer unit is preferably 15 / 85 to 50 / 50, more preferably 25 / 75 to 50 / 50, and even more preferably 28 / 72 to 42 / 58.

[0110] When the ratio of each monomer unit is within the above range, the regenerated ABS resin composition of the present embodiment tends to have a better balance between the rigidity and impact strength of the molded article.

[0111] In the range where the mass ratio of the vinyl aromatic monomer units in the hydrogenated block copolymer (x) is from 15% by mass to 35% by mass, although the elastic modulus of the resulting recycled ABS resin composition is slightly reduced, the composition tends to exhibit high impact strength and has a performance comparable to that of the virgin ABS resin (a*) alone.

[0112] On the other hand, in the range where the mass ratio of the vinyl aromatic monomer units in the hydrogenated block copolymer (x) is greater than 35% by mass and less than 50% by mass, a recycled ABS resin composition having a well-balanced mechanical properties while maintaining the elastic modulus of the original recycled ABS resin (a) tends to be obtained.

[0113] As described above, in the hydrogenated block copolymer (x), the mass ratio of the vinyl aromatic monomer units in the hydrogenated block copolymer (x) is preferably selected from the viewpoint of the physical properties to be emphasized in view of the final application.

[0114] The contents of the vinyl aromatic monomer unit and the conjugated diene monomer unit in the hydrogenated block copolymer (x) can be quantified by the method described in the Examples below.

[0115] The content of these monomer units can be controlled by adjusting the amount and ratio of each monomer added in the polymerization step of the hydrogenated block copolymer (x).

[0116] The hydrogenated block copolymer (x) is not particularly limited, and examples thereof include block copolymers having block structures represented by the following general formulae (1) to (5).

[0117] SB…(1)

[0118] S-(BS) n …(2)

[0119] B-(SB) n …(3)

[0120] S-(BSB) n …(4)

[0121] (SB) n X…(5)

[0122] Here, S represents a polymer block mainly composed of vinyl aromatic monomer units, and B represents a polymer block mainly composed of hydrogenated conjugated diene monomer units. Furthermore, n represents an integer from 1 to 6. Each of n in (2) to (5) is independent of the others and may be the same or different. X represents a coupling agent residue.

[0123] The above-mentioned general formulas (1) to (4) are linear hydrogenated block copolymers, and (5) is a branched (also called star-shaped) hydrogenated block copolymer with the B portion as the bonding center, and both can be suitably used.

[0124] When the recycled ABS resin composition of the present embodiment is used in durable consumer goods or the like requiring mechanical properties at a certain level or higher, the hydrogenated block copolymer (x) is preferably selected to have at least one polymer block S mainly composed of vinyl aromatic monomer units, and more preferably has at least two polymer blocks S.

[0125] In addition, in this specification, a "polymer block mainly composed of vinyl aromatic monomer units" may be simply referred to as a "polymer block S."

[0126] <Peak Molecular Weight and Molecular Weight Distribution of Hydrogenated Block Copolymer (x)>

[0127] The hydrogenated block copolymer (x) preferably has at least one peak molecular weight within the molecular weight range of 20,000 to 250,000 in a molecular weight distribution curve measured by gel permeation chromatography (GPC). This tends to improve the mechanical properties of the recycled ABS resin composition of this embodiment.

[0128] From the same perspective, the peak molecular weight of the hydrogenated block copolymer (x) is more preferably within the range of 30,000 to 150,000, and even more preferably within the range of 35,000 to 100,000. The peak molecular weight of the hydrogenated block copolymer (x) can be measured by the method described in the Examples below.

[0129] Regarding the molecular weight distribution of the hydrogenated block copolymer (x), if simple anionic polymerization is used, the molecular weight distribution is unimodal, and a polymer having a relatively uniform molecular weight and a narrow distribution is obtained. However, by, for example, associating the polymerization active ends of some polymers using a coupling agent described later, or by combining polymers having different molecular weights, a hydrogenated block copolymer (x) having a deliberately broadened molecular weight distribution can be obtained.

[0130] <Content and Molecular Weight of Polymer Block S of Hydrogenated Block Copolymer (x)>

[0131] The content of the polymer block S mainly composed of vinyl aromatic monomer units in the hydrogenated block copolymer (x) is obtained by calculating the mass ratio of the polymer block S component (excluding the vinyl aromatic hydrocarbon monomer polymer component having an average degree of polymerization of about 30 or less) obtained by using osmium tetroxide as a catalyst and tert-butyl hydroperoxide to oxidatively decompose the block copolymer (IMKOLTHOFF, et al., J. Polym. Sci. 1, 429 (1946)). In addition, the molecular weight (Mn and Mw) of the polymer block S component obtained by the above method can be obtained by measuring the polymer block S component using gel permeation chromatography (GPC). In this specification, this method is described as the "osmium tetroxide method".

[0132] The content of the polymer block S in the hydrogenated block copolymer (x) can also be determined by using a nuclear magnetic resonance (NMR) method (described in Y. Tanaka et al., RUBBER CHEMISTRY and TECHNOLOGY 54, 685 (1981)) using the block copolymer before or after hydrogenation as an analyte. This analytical method is referred to herein as the "NMR method."

[0133] In this case, the content of the polymer block S mainly composed of vinyl aromatic monomer units, measured by the osmium tetroxide method using the block copolymer before hydrogenation, is represented by (Os). This content has a correlation with the content of the polymer block S mainly composed of vinyl aromatic monomer units, measured by the NMR method using the block copolymer after hydrogenation (represented as Ns), as shown in the following formula (F).

[0134] (Os)=-0.012(Ns)2+1.8(Ns)-13.0···(F)

[0135] Therefore, when the content of the polymer block S of the hydrogenated block copolymer (x) is determined by NMR, the value of (Os) determined by the above formula (F) can be regarded as the content of the polymer block S mainly composed of vinyl aromatic monomer units specified in this embodiment.

[0136] (Modified hydrogenated block copolymer (b*))

[0137] The hydrogenated block copolymer (x) contains 30% by mass or more and 100% by mass or less of a modified hydrogenated block copolymer (b*) in the hydrogenated block copolymer (x), wherein the modified hydrogenated block copolymer (b*) has at least one molecule of a heteroatom-containing functional group chemically bonded to a polymer graft chain, a polymer terminal, or a coupling agent residue.

[0138] Generally, heteroatoms refer to all elements other than carbon and hydrogen in hydrocarbon compounds. Representative examples of heteroatoms in organic compounds containing hydrocarbons as the main component include oxygen, nitrogen, boron, sulfur, phosphorus, silicon, halogens, and tin.

[0139] Generally, a functional group is an atomic group that has a charge bias between covalently bonded atoms. Generally, the atomic group containing a heteroatom forms a covalent bond with the hydrogenated block copolymer.

[0140] By using a hydrogenated block copolymer (x) containing 30% to 100% by mass of the modified hydrogenated block copolymer (b*) in the recycled ABS resin composition of this embodiment, affinity for the ABS resin, which is the main component of the recycled ABS resin (a) to be modified, is achieved through hydrogen bonding with acrylonitrile, one of the monomer components, thereby exhibiting a modification effect. Furthermore, the hydrogenated block copolymer (x) forms covalent bonds with polar impurities such as plating components and coating components, and polar foreign resins such as polyamide, contained as impurities in the recycled ABS resin (a) through hydrogen bonding or grafting reactions. The interfaces between the foreign resins and polar impurities are strengthened through chemical bonding or hydrogen bonding, and the compatibility of these components is achieved, resulting in a significant improvement in mechanical properties.

[0141] By including the modified hydrogenated block copolymer (b*) in the recycled ABS resin composition of the present embodiment, the ABS resin can be reinforced and also exhibit the effect of compatibilizing different resins, foreign matter, and the like.

[0142] Furthermore, when the recycled ABS resin composition of the present embodiment contains a filler as a compounding material, the graft reaction with the filler tends to also produce an effect of promoting the dispersion of the filler.

[0143] The amount of the functional group added to the modified hydrogenated block copolymer (b*) is generally from 0.01% by mass to 10% by mass, preferably from 0.01% by mass to 8.0% by mass, more preferably from 0.05% by mass to 6.0% by mass, and even more preferably from 0.05% by mass to 4.0% by mass, relative to 100% by mass of the hydrogenated block copolymer (x).

[0144] When the amount of added functional groups is 0.01% by mass or more and 10% by mass or less, the effect of improving the impact resistance of the recycled ABS resin composition of the present embodiment tends to be maximized.

[0145] The hydrogenated block copolymer (x) contains 30% by mass or more and 100% by mass or less of a modified hydrogenated block copolymer (b*) in the hydrogenated block copolymer (x), wherein at least one molecule of a functional group containing a heteroatom is chemically bonded to a polymer graft chain, a polymer terminal, or a coupling agent residue in the modified hydrogenated block copolymer (b*).

[0146] The hydrogenated block copolymer (x) must contain 30% by mass or more of the modified hydrogenated block copolymer (b*). By containing 30% by mass or more of the modified hydrogenated block copolymer (b*), a high modification effect tends to be achieved on the recycled ABS resin (a).

[0147] The content of the modified hydrogenated block copolymer (b*) in the hydrogenated block copolymer (x) is more preferably 40% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, particularly preferably 90% by mass or more, and most preferably 100% by mass.

[0148] Examples of the heteroatom-containing functional group include, but are not limited to, a hydroxyl group, a carboxyl group, a carbonyl group, a thiocarbonyl group, an acyl halide group, an acid anhydride group, a carboxylic acid group, a thiocarboxylic acid group, an aldehyde group, a thialdehyde group, a carboxylate group, an amide group, a sulfonic acid group, a sulfonate group, a phosphoric acid group, a phosphate group, an amino group, an imino group, a nitrile group, a pyridyl group, a quinolyl group, an epoxy group, a thioepoxy group, a thioether group, an isocyanate group, an isothiocyanate group, a silicon halide group, a silanol group, an alkoxysilyl group, a tin halide group, a boric acid group, a boron-containing group, a borate group, an alkoxytin group, and a phenyltin group. The group may be an atomic group containing at least one of these functional groups.

[0149] In particular, it is preferred that the atomic group has at least one functional group selected from the group consisting of an acid anhydride group, a carboxylic acid group, a hydroxyl group, an epoxy group, an amino group, an amide group, a silanol group and an alkoxysilyl group, more preferably the atomic group has at least one functional group selected from the group consisting of an acid anhydride group, a carboxylic acid group, a hydroxyl group, an epoxy group, an amino group and an amide group, and further preferably the atomic group has at least one functional group selected from the group consisting of an acid anhydride group, a carboxylic acid group and a hydroxyl group.

[0150] In the functional group formation step, when the acid anhydride is bonded to the block copolymer, moisture in the air and the like may react with the acid anhydride to partially convert into carboxylic acid groups to form functional groups. However, the amount thereof is not particularly limited.

[0151] From the viewpoint of improving compatibility with ABS-based resins and achieving a high modification effect, the modified hydrogenated block copolymer (b*) particularly preferably has a functional group on at least one polymer terminal and / or a coupling agent residue.

[0152] From the perspective of improving compatibility with ABS-based resins and achieving a high modification effect, the modified hydrogenated block copolymer (b*) particularly preferably has a functional group at at least one polymer terminal, wherein the functional group is any one selected from the group consisting of a primary amino group, a secondary amino group, and an epoxy group.

[0153] <Method for producing hydrogenated block copolymer (x)>

[0154] The hydrogenated block copolymer (x) can be produced by utilizing a known technique.

[0155] Representative prior art techniques include block copolymerization of a conjugated diene compound and a vinyl aromatic compound using an anionic initiator such as an organolithium compound in a hydrocarbon solvent. For example, the block copolymerization can be performed by the methods described in Japanese Patent Publication No. 36-19286, Japanese Patent Publication No. 43-17979, Japanese Patent Publication No. 48-2423, Japanese Patent Publication No. 49-36957, Japanese Patent Publication No. 57-49567, and Japanese Patent Publication No. 58-11446.

[0156] [Polymerization solvent]

[0157] The hydrogenated block copolymer (x) is obtained by block copolymerizing a vinyl aromatic compound and a conjugated diene compound in a hydrocarbon solvent.

[0158] As the hydrocarbon solvent used in the production of the hydrogenated block copolymer (x), any conventionally known hydrocarbon solvent may be used. Examples thereof include, but are not limited to, aliphatic hydrocarbons such as n-butane, isobutane, n-pentane, n-hexane, n-heptane, and n-octane; alicyclic hydrocarbons such as cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, cycloheptane, and methylcycloheptane; and aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene.

[0159] These hydrocarbon solvents may be used alone or in combination of two or more. Among these, when an organic lithium initiator is used, the hydrocarbon solvent is usually n-hexane or cyclohexane, of which cyclohexane is the most commonly used in industry and can be preferably used.

[0160] [Polymerization initiator]

[0161] The polymerization initiator is not particularly limited, and for example, a polymerization initiator that exhibits anionic polymerization activity toward conjugated diene compounds and vinyl aromatic compounds can be suitably used. Examples thereof include alkali metal compounds such as aliphatic hydrocarbon alkali metal compounds, aromatic hydrocarbon alkali metal compounds, and organic amino alkali metal compounds.

[0162] The alkali metal used in the alkali metal compound is not particularly limited, and examples thereof include lithium, sodium, and potassium.

[0163] Suitable alkali metal compounds include, but are not limited to, aliphatic and aromatic hydrocarbon lithium compounds having 1 to 20 carbon atoms, compounds containing one lithium in one molecule, and dilithium compounds, trilithium compounds, and tetralithium compounds containing multiple lithiums in one molecule.

[0164] Examples of such alkali metal compounds include, but are not limited to, n-propyllithium, n-butyllithium, sec-butyllithium, tert-butyllithium, hexamethylenedilithium, butadienyldilithium, isoprenyldilithium, the reaction product of diisopropenylbenzene and sec-butyllithium, and the reaction product of divinylbenzene, sec-butyllithium and a small amount of 1,3-butadiene.

[0165] Organic alkali metal compounds disclosed in foreign patents shown in U.S. Patent No. 5,708,092, British Patent No. 2,241,239, and U.S. Patent No. 5,527,753 can also be used. These can be used alone or in combination of two or more. Among these, n-butyl lithium is most preferred.

[0166] [Polymerization process]

[0167] In the polymerization process of the hydrogenated block copolymer (x), by adjusting the charging ratio of the vinyl aromatic compound and the conjugated diene compound as polymerization raw materials, the content of the vinyl aromatic monomer unit and the content of the conjugated diene monomer unit in the finally obtained hydrogenated block copolymer (x) can be controlled.

[0168] As polymerization processes for the hydrogenated block copolymer (x), for example, a process of adding a polymerization initiator midway through polymerization; a process of partially causing a coupling reaction by adding a small amount of a polyfunctional monomer having two or more reactive sites; or a process of adding an alcohol, water, or the like at a temperature below the polymerization active point midway through polymerization, followed by further monomer supply and continued polymerization, etc., can be appropriately employed. By appropriately selecting such processes, a hydrogenated block copolymer (x) containing multiple components having different molecular weights can be produced.

[0169] Alternatively, a hydrogenated block copolymer (x) can be obtained as a mixture of polymers having different molecular weights by adding an alcohol such as ethanol in a molar equivalent smaller than the number of moles of the polymerization initiator to the polymerization system during polymerization to stop polymerization of part of the polymer.

[0170] Methods for producing copolymer blocks composed of vinyl aromatic monomer units and conjugated diene monomer units include: a method in which a mixture of a vinyl aromatic compound and a conjugated diene compound is continuously supplied to a polymerization system for polymerization; a method in which a vinyl aromatic compound and a conjugated diene compound are copolymerized using a polar compound or a randomizer; and the like.

[0171] Furthermore, when a conjugated diene compound is polymerized alone, the polar compound or randomizer also has the effect of increasing the ratio of vinyl bonds in the conjugated diene.

[0172] The vinyl bond content of the hydrogenated block copolymer (x) can be controlled by using a Lewis base, for example, a compound such as ether or amine, as a vinylating agent.

[0173] The target vinyl bond amount can be controlled by adjusting the amount of the vinylating agent used.

[0174] Examples of the vinylating agent include, but are not limited to, ether compounds and tertiary amine compounds.

[0175] Examples of the ether compound as the vinylating agent include, but are not limited to, ethers such as tetrahydrofuran, diethylene glycol dimethyl ether, and diethylene glycol dibutyl ether.

[0176] Examples of tertiary amine compounds include, but are not limited to, pyridine, N,N,N',N'-tetramethylethylenediamine, tributylamine, tetramethylpropylenediamine, 1,2-dipiperidylethane, and bis[2-(N,N-dimethylamino)ethyl]ether.

[0177] These compounds may be used alone or in combination of two or more.

[0178] As the tertiary amine compound, a compound having two amines is preferred. Among these, a compound having a symmetrical structure in the molecule is more preferred, and N,N,N',N'-tetramethylethylenediamine, bis[2-(N,N-dimethylamino)ethyl]ether, and 1,2-dipiperidinylethane are even more preferred.

[0179] The hydrogenated block copolymer (x) can be produced in the presence of an alkali metal alkoxide for the purpose of controlling the vinyl bond content. Alkali metal alkoxides are compounds represented by the general formula: MOR (wherein M is an alkali metal and R is an alkyl group). The use of such alkali metal alkoxides can yield hydrogenated block copolymers (x) having a high vinyl bond content.

[0180] As the alkali metal of the alkali metal alkoxide, sodium or potassium is preferred from the viewpoints of a high vinyl bond content, a narrow molecular weight distribution, a high polymerization rate, and a high blocking ratio.

[0181] Examples of the alkali metal alkoxide include, but are not limited to, sodium alkoxides, lithium alkoxides, and potassium alkoxides having an alkyl group with 2 to 12 carbon atoms. Preferred are sodium alkoxides and potassium alkoxides having an alkyl group with 3 to 6 carbon atoms. More preferred are sodium tert-butoxide, sodium tert-amylate, potassium tert-butoxide, and potassium tert-amylate. Among these, sodium tert-butoxide and sodium tert-amylate are more preferred as sodium alkoxides.

[0182] In the polymerization process of the hydrogenated block copolymer (x), when the polymerization is carried out in the coexistence of a vinylating agent, an organic lithium compound and an alkali metal alkoxide, it is preferred that the molar ratio of the vinylating agent to the organic lithium compound (vinylating agent / organic lithium compound) and the molar ratio of the alkali metal alkoxide to the organic lithium compound (alkali metal alkoxide / organic lithium compound) are such that they coexist in the following molar ratios.

[0183] Vinylating agent / organic lithium compound molar ratio: 0.2-3.0

[0184] Alkali metal alkoxide / organic lithium compound molar ratio: 0.01-0.3

[0185] The molar ratio of the vinylating agent / organolithium compound is preferably 0.2 or more from the viewpoint of a high vinyl bond content and a high polymerization rate, and is preferably 3.0 or less from the viewpoint of a narrow molecular weight distribution and high hydrogenation activity.

[0186] The molar ratio of the alkali metal alkoxide to the organolithium compound is preferably 0.01 or higher from the perspectives of a high vinyl bond content, a high polymerization rate, and a high block ratio, and is preferably 0.3 or lower from the perspectives of a narrow molecular weight distribution and high hydrogenation activity. This tends to increase the polymerization rate, increase the vinyl bond content of the target hydrogenated block copolymer (x), narrow the molecular weight distribution, and thus increase the block ratio.

[0187] As a result, by controlling the vinyl bond content of the hydrogenated block copolymer (x), crystallization of the polyethylene structure originating from the hydrogenated conjugated diene block portion can be suppressed, thereby exhibiting soft elastomer properties. Furthermore, in addition to functioning as a compatibilizer, various required properties depending on the application, such as impact resistance, flexibility, and transparency, can be met.

[0188] The optimal polymerization temperature in the polymerization step of the hydrogenated block copolymer (x) varies depending on the polymer structure, but in the case of anionic polymerization using a polymerization initiator, it is generally in the range of -10°C to 150°C, preferably 10°C to 100°C.

[0189] The time required for polymerization is usually within 48 hours, preferably in the range of 0.1 hours to 10 hours.

[0190] In addition, the atmosphere of the polymerization system is preferably replaced with an inert gas such as nitrogen.

[0191] The polymerization pressure is not particularly limited as long as it is within a pressure range sufficient to maintain the monomer and the polymerization solvent in a liquid layer within the above-mentioned polymerization temperature range.

[0192] Furthermore, it is preferred to take care not to accidentally introduce impurities such as water, oxygen, and carbon dioxide that may deactivate the polymerization initiator and the living polymer into the polymerization system.

[0193] When obtaining a hydrogenated block copolymer (x) containing a random copolymer block, it is preferred to adopt a method such as continuously supplying a mixture of a vinyl aromatic compound and a conjugated diene compound to a polymerization system and polymerizing the mixture, and / or copolymerizing the vinyl aromatic compound and the conjugated diene compound using a polar compound or a randomizer.

[0194] In the production of the hydrogenated block copolymer (x), when an organic alkali metal is used as a polymerization initiator, the polymerization reaction is usually terminated by adding a hydroxyl or carboxyl group-containing compound such as an alcohol or a fatty acid that can donate active hydrogen as a polymerization terminator in an equimolar amount relative to the organic lithium compound as the polymerization initiator.

[0195] On the other hand, in the production of the hydrogenated block copolymer (x) constituting the recycled ABS resin composition of the present embodiment, preferred methods include producing the modified hydrogenated block copolymer (b*) by utilizing a coupling reaction in which two or more molecules are bonded using a coupling agent containing a heteroatom to terminate the polymerization reaction; and by using a modifying agent containing a heteroatom, particularly a modifying agent capable of forming an amino group, as a polymerization terminator to introduce a functional group at the polymerization terminal to terminate the polymerization reaction.

[0196] The method of using a modifier capable of forming an amino group at a polymer terminal as a polymerization terminator will be described in detail in the "Modification Step" described later.

[0197] The coupling reaction at the time of stopping the polymerization can be carried out by adding the coupling agent exemplified below to the polymerization system.

[0198] Furthermore, by adjusting the amount of coupling agent added, only a portion of the polymer in the polymerization system can be coupled, allowing uncoupled polymer and coupled polymer to coexist, thereby producing a hydrogenated block copolymer (x) having two or more peaks in the molecular weight distribution.

[0199] Furthermore, since coupling agents often contain heteroatoms, after the coupling reaction, functional groups containing heteroatoms derived from the coupling agent residues in the polymer chain also exhibit a modification effect. Therefore, as long as the presence of coupling agent residues can be confirmed, a hydrogenated block copolymer utilizing the coupling reaction can also be considered a modified hydrogenated block copolymer (b*).

[0200] The coupling agent that can be suitably used in the production of the hydrogenated block copolymer (x) is not particularly limited, and examples thereof include any coupling agent having two or more functional groups.

[0201] Specifically, there can be mentioned amino group-containing silane compounds such as tetraglycidyl-m-phenylenediamine, tetraglycidyl-1,3-bisaminomethylcyclohexane, tetraglycidyl-p-phenylenediamine, tetraglycidyldiaminodiphenylmethane, diglycidylaniline, diglycidyl-o-toluidine, γ-glycidoxyethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxybutyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltripropoxysilane, and γ-glycidoxypropyltributoxysilane.

[0202] In addition, as other coupling agents, for example, 1-[3-(triethoxysilyl)-propyl]-4-methylpiperazine, 1-[3-(diethoxyethylsilyl)-propyl]-4-methylpiperazine, 1-[3-(trimethoxysilyl)-propyl]-3-methylimidazoline, 1-[3-(diethoxyethylsilyl)-propyl]-3-ethylimidazoline, 1-[3-(triethoxysilyl)-propyl]-3-methylhexahydropyrimidine, 1-[3-(dimethoxymethylsilyl)-propyl]-3-methylimidazoline, Silane compounds containing a silyl group include silane compounds such as 1-[3-(trimethoxysilyl)propyl]-1-methyl-1,2,3,4-tetrahydropyrimidine, 3-[3-(dimethoxymethylsilyl)propyl]-1-ethyl-1,2,3,4-tetrahydropyrimidine, 1-(2-ethoxyethyl)-3-[3-(trimethoxysilyl)propyl]-imidazoline, and (2-{3-[3-(trimethoxysilyl)propyl]-tetrahydropyrimidin-1-yl}-ethyl)dimethylamine.

[0203] Examples of other coupling agents include γ-glycidoxypropyl triphenoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylethyldimethoxysilane, γ-glycidoxypropylethyldiethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropylmethyldipropoxysilane, γ-glycidoxypropylmethyldibutoxysilane, γ-glycidoxypropylmethyldiphenoxysilane, γ-glycidoxypropyldimethylmethoxysilane, γ-glycidoxypropyldiethylethoxysilane, γ-glycidoxypropyldimethylethoxysilane, γ-glycidoxypropyldimethylphenoxysilane, γ-glycidoxypropyldiethylmethoxysilane, Silane compounds containing a glycidoxy group such as γ-glycidoxypropylmethyldiisopropenoxysilane, bis(γ-glycidoxypropyl)dimethoxysilane, bis(γ-glycidoxypropyl)diethoxysilane, bis(γ-glycidoxypropyl)dipropoxysilane, bis(γ-glycidoxypropyl)dibutoxysilane, bis(γ-glycidoxypropyl)diphenoxysilane, bis(γ-glycidoxypropyl)methylmethoxysilane, bis(γ-glycidoxypropyl)methylethoxysilane, bis(γ-glycidoxypropyl)methylpropoxysilane, bis(γ-glycidoxypropyl)methylbutoxysilane, bis(γ-glycidoxypropyl)methylphenoxysilane, and tris(γ-glycidoxypropyl)methoxysilane.

[0204] In addition, as other coupling agents, for example, silane compounds containing a methacryloxy group such as γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-methacryloxymethyltrimethoxysilane, γ-methacryloxyethyltriethoxysilane, bis(γ-methacryloxypropyl)dimethoxysilane, and tris(γ-methacryloxypropyl)methoxysilane can be mentioned.

[0205] In addition, examples of other coupling agents include β-(3,4-epoxycyclohexyl)ethyl-trimethoxysilane, β-(3,4-epoxycyclohexyl)ethyl-triethoxysilane, β-(3,4-epoxycyclohexyl)ethyl-tripropoxysilane, β-(3,4-epoxycyclohexyl)ethyl-tributoxysilane, β-(3,4-epoxycyclohexyl)ethyl-triphenoxysilane, β-(3,4-epoxycyclohexyl)propyl-trimethoxysilane, β-(3,4-epoxycyclohexyl)ethyl-methyldimethoxysilane, β-(3,4-epoxycyclohexyl)ethyl-ethyldimethoxysilane, β-(3,4-epoxycyclohexyl)ethyl-ethyldiethoxysilane, β-(3,4-epoxycyclohexyl)ethyl-methyldiethoxysilane, β-(3,4-epoxycyclohexyl)ethyl-methyl Silane compounds containing epoxycyclohexyl groups, such as dipropoxysilane, β-(3,4-epoxycyclohexyl)ethyl-methyldibutoxysilane, β-(3,4-epoxycyclohexyl)ethyl-methyldiphenoxysilane, β-(3,4-epoxycyclohexyl)ethyl-dimethylmethoxysilane, β-(3,4-epoxycyclohexyl)ethyl-diethylethoxysilane, β-(3,4-epoxycyclohexyl)ethyl-dimethylethoxysilane, β-(3,4-epoxycyclohexyl)ethyl-dimethylpropoxysilane, β-(3,4-epoxycyclohexyl)ethyl-dimethylbutoxysilane, β-(3,4-epoxycyclohexyl)ethyl-dimethylphenoxysilane, β-(3,4-epoxycyclohexyl)ethyl-diethylmethoxysilane, and β-(3,4-epoxycyclohexyl)ethyl-methyldiisopropenoxysilane.

[0206] Examples of other coupling agents include 1,3-dimethyl-2-imidazolidinone, 1,3-diethyl-2-imidazolidinone, N,N′-dimethylpropyleneurea, and N-methylpyrrolidone.

[0207] It should be noted that when the modified hydrogenated block copolymer (b*) is obtained by subjecting the coupling agent to an addition reaction with the polymerization active end of the hydrogenated block copolymer, the structure of the active end of the hydrogenated block copolymer is not particularly limited. However, from the perspective of mechanical strength of the regenerated ABS resin composition of this embodiment, the active end is preferably an active end of a polymer block mainly composed of vinyl aromatic monomer units.

[0208] The amount of the coupling agent used is preferably 0.05 equivalents to 1 equivalent, more preferably 0.1 equivalents to 1 equivalent, relative to 1 equivalent of the active terminal of the hydrogenated block copolymer.

[0209] The coupling agents may be used alone or in combination of two or more.

[0210] By using a coupling agent having a functional group containing a heteroatom and a modifier capable of forming an amino group at the polymer terminal while taking into account the molar amount of the organolithium compound, a modified hydrogenated block copolymer (b*) having both a functional group containing a heteroatom and an amino group can be produced.

[0211] When a modifier capable of forming an amino group at the polymer terminal is not used, and when no heteroatom remains in the polymer molecular chain after the coupling reaction among the above coupling agents, it is not considered as a modified hydrogenated block copolymer (b*).

[0212] The functional group containing a heteroatom can be expected to exhibit interaction with the recycled ABS-based resin (a) such as hydrogen bonding.

[0213] For example, when a coupling reaction is carried out using tetraglycidyl-1,3-bisaminomethylcyclohexane having a tertiary amino group and an epoxy group, and in a molecular weight distribution curve obtained by GPC, if the ratio of the number average molecular weight of the coupled polymer to the number average molecular weight Mn of the uncoupled polymer is 3.2 times, it can be easily estimated that an average of 0.8 unreacted coupling residues are present.

[0214] [Hydrogenation process]

[0215] The hydrogenated block copolymer (x) is produced by subjecting a part or all of the double bonds in the conjugated diene monomer units of the block copolymer obtained in the polymerization step to a hydrogenation reaction.

[0216] Examples of catalysts used in the hydrogenation reaction include, but are not limited to, supported heterogeneous catalysts in which metals such as Ni, Pt, Pd, and Ru are supported on supports such as carbon, silica, alumina, and diatomaceous earth; Ziegler-type catalysts using organic salts or acetylacetonates of Ni, Co, Fe, and Cr and reducing agents such as organic Al; organic complex catalysts such as organometallic compounds of Ru and Rh; and homogeneous catalysts using organic Li, organic Al, and organic Mg as reducing agents in cyclopentadienyl titanium compounds. Among these, homogeneous catalyst systems using organic Li, organic Al, and organic Mg as reducing agents in cyclopentadienyl titanium compounds are preferred from the perspectives of economic efficiency, polymer colorability, and adhesion.

[0217] Examples of hydrogenation methods include, but are not limited to, methods described in JP-B-42-8704 and JP-B-43-6636, and preferably methods described in JP-B-63-4841 and JP-B-63-5401. Specifically, hydrogenation can be performed in an inert solvent in the presence of a hydrogenation catalyst to obtain a hydrogenated block copolymer solution.

[0218] The hydrogenation reaction is not particularly limited, but is preferably performed after the above-mentioned deactivation step of the active terminal of the polymer in order to exhibit high hydrogenation activity. The hydrogenation step can be performed by any of a batch process, a continuous process, or a combination thereof.

[0219] In the hydrogenation step, part of the conjugated bonds of the vinyl aromatic monomer units can be hydrogenated.

[0220] The hydrogenation rate of conjugated bonds in all vinyl aromatic monomer units is preferably 30 mol% or less, more preferably 10 mol% or less, and even more preferably 3 mol% or less.

[0221] In consideration of the development of mechanical properties by forming a microphase separation structure, it is preferred that the vinyl aromatic monomer unit is not hydrogenated and the hydrogenation rate is close to 0 mol%.

[0222] [Modification process]

[0223] The hydrogenated block copolymer (x) contains at least 30% by mass or more of a modified hydrogenated block copolymer (b*) produced by introducing a functional group through a modification step.

[0224] The modified hydrogenated block copolymer (b*) and the unmodified hydrogenated block copolymer (b) may have the same or different ratios of the vinyl aromatic monomer units and the conjugated diene monomer units, the hydrogenation ratio, the molecular weight, and the like.

[0225] The modification method can be a known method. During the polymerization step, a method of modifying the copolymer by using a compound having a functional group in a polymerization initiator and / or polymerization terminator (terminal modification) can be implemented. Alternatively, the following method can be implemented: using a single-screw or twin-screw extruder, with or without a free radical initiator, adding an unsaturated compound having a functional group to modify the hydrogenated block copolymer after the polymerization step (main chain modification) can be implemented. In order to introduce functional groups using a polymerization initiator, the above-mentioned organic amino alkali metal compound is generally used for polymerization.

[0226] Specific methods for introducing functional groups into hydrogenated block copolymers include, for example, melt kneading using an extruder or the like, and methods involving dissolution, dispersion, and mixing using a solvent. This is referred to as a grafting reaction or main chain modification. Furthermore, methods for polymerizing the hydrogenated block copolymer (x) using monomers having functional groups, or methods for terminating polymerization by modifying the block copolymer with a compound having a functional group rather than conventional alcohols during the polymerization termination reaction, can also be employed. This is referred to as terminal modification.

[0227] Examples of modifiers that form functional groups in polymers, specifically modifiers that can form carboxylic acid groups or dicarboxylic anhydride groups or contain these functional groups, include, but are not limited to, maleic acid, maleic anhydride, maleic anhydride imide, fumaric acid, itaconic acid, acrylic acid, methacrylic acid, glycidyl methacrylate, and crotonic acid.

[0228] By using these modifiers, polymer graft chains can be formed mainly on the main chain of the hydrogenated block copolymer. By adjusting the amount of addition and the addition reaction conditions, modified block copolymers having multiple functional groups can be prepared.

[0229] On the other hand, a terminally modified hydrogenated block copolymer having a functional group at a terminal is obtained by adding a modifier capable of forming an amino group or a modifier containing an amino group, as exemplified below, to a polymerization system.

[0230] Furthermore, the modification rate can be controlled by adjusting the amount of the modifying agent capable of forming an amino group or the modifying agent containing an amino group added.

[0231] Examples of the modifier capable of forming an amino group or the modifier containing an amino group include, but are not limited to, tetraglycidyl-m-xylylenediamine, tetraglycidyl-1,3-bisaminomethylcyclohexane, ε-caprolactone, δ-valerolactone, 4-methoxybenzophenone, γ-glycidoxyethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyldimethylphenoxysilane, bis(γ-glycidoxypropyl)methylpropoxysilane, 1,3-dimethyl-2-imidazolidinone, 1,3-diethyl-2-imidazolidinone, N,N'-dimethylpropyleneurea, and N-methylpyrrolidone.

[0232] The amount of the modifier added to the hydrogenated block copolymer (x) can be measured by a known analytical method.

[0233] As a general method, for example, in the case of maleic anhydride modification, a titration method using sodium methoxide can be exemplified.

[0234] From the perspective of processability and mechanical properties of the recycled ABS resin composition of this embodiment, the melt flow rate (ISO 1133 temperature 230°C, load 2.16 kgf) of the hydrogenated block copolymer (x) is preferably 0.01 to 50 g / 10 min, more preferably 0.03 to 20 g / 10 min, and even more preferably 0.05 to 10 g / 10 min. The hydrogenated block copolymer (x) is preferably domain-dispersed in the recycled ABS resin (a), and a low MFR of approximately 0.1 g / 10 min tends to be useful in terms of physical property development when kneading using a twin-screw extruder.

[0235] (Other additives that can be mixed into the recycled ABS resin composition)

[0236] The recycled ABS resin composition of the present embodiment may contain optional compounding agents and additives within the range that does not depart from the gist of the present invention and does not inhibit the effects of the present invention.

[0237] Examples of compounding agents and additives include substances commonly used in the compounding of resins or rubber-like polymers, including but not limited to inorganic fillers such as calcium carbonate, magnesium carbonate, silicon oxide, zinc oxide, and carbon black; higher alcohols such as stearyl alcohol; higher fatty acids such as palmitic acid, stearic acid, and behenic acid; higher fatty acid metal salts such as zinc stearate, calcium stearate, magnesium stearate, magnesium behenate, and magnesium hydrogenated ricinoleate; lubricants and release agents such as fatty acid amides such as erucamide and ethylene bisstearamide; organopolysiloxanes such as paraffin oil, process oil, dimethyl silicone, and methylphenyl silicone; softeners and plasticizers such as mineral oil; hindered phenol-based and phosphorus-based heat stabilizers and antioxidants; hindered amine-based light stabilizers; benzotriazole-based ultraviolet absorbers; halogen-based and phosphorus-based flame retardants; reinforcing agents such as organic fibers, glass fibers, carbon fibers, and metal whiskers; colorants such as organic pigments, inorganic pigments, and organic dyes; and the like.

[0238] (Method for producing recycled ABS resin composition)

[0239] The method for producing the recycled ABS resin composition of this embodiment is not particularly limited. For example, the following method can be used: recycled ABS resin (a) recovered from a product is first pelletized using an extruder or the like. Then, a hydrogenated block copolymer (x) including a modified hydrogenated block copolymer (b*) is combined with the recycled ABS resin (a). The pellets are dry-blended at room temperature with or without the use of a tumble mixer, Henschel mixer, or the like, as required. The pellets are then fed into the feed hopper of a twin-screw extruder, heated and melt-kneaded in the twin-screw extruder, and the heated and melted ABS resin composition is extruded from a die into strands. The strands are then passed through a cooling bath to pelletize the composition again. This composition is obtained as a pelletized ABS resin composition.

[0240] During heat-melt kneading, any kneading machine for thermoplastic resins capable of heat-melting is not particularly limited, and for example, a kneader such as a kneader, a Banbury mixer, a roll, a ribbon blender, a single-screw extruder, or a twin-screw extruder can be suitably used.

[0241] In addition, not only the strand cutting method using a cooling bath but also a heat cutting method, an underwater cutting method, and the like can be preferably used depending on the purpose.

[0242] (Mass ratio of recycled ABS resin to hydrogenated block copolymer (x))

[0243] In the recycled ABS resin composition of this embodiment, the mass ratio of the recycled ABS resin (a) to the hydrogenated block copolymer (x) is (a) / (x) = 99 / 1 to 80 / 20, preferably (a) / (x) = 97 / 3 to 85 / 15, and more preferably 96 / 4 to 90 / 10.

[0244] By adopting the above-mentioned mass ratio, a recycled ABS-based resin composition can be obtained that has a balance of mechanical properties such as impact strength close to that of the original virgin ABS-based resin and is suitable for practical use.

[0245] Example

[0246] The present embodiment will be described in further detail below with reference to specific examples and comparative examples. However, the present invention is not limited to the following examples and comparative examples.

[0247] [Recycled ABS resin (a), virgin ABS resin (a*)]

[0248] As the recycled ABS resin (a), automobile-derived recycled ABS resin (a)-1 and home appliance-derived recycled ABS resin (a)-2, manufactured and sold by Kansai Chemical Industry Co., Ltd., were obtained and used, respectively, using two classification technologies: gravity separation and electrostatic separation.

[0249] On the other hand, as the virgin ABS resin (a*), an ABS resin "Polylac PA-757" manufactured and sold by Chi Mei Industrial Co., Ltd. was obtained and used as the virgin ABS resin (a*)-3.

[0250] The melt flow rate of Polylac PA-757 is 23 g / 10 minutes under the conditions of ISO 1133, a temperature of 220° C., and a load of 10 kgf.

[0251] [Identification of Impurities Contained in Recycled ABS-Based Resin (a) and Calculation of Purity of ABS-Based Resin]

[0252] About 0.2 g of the obtained recycled ABS resin (a) of unknown composition was accurately weighed and dissolved in 10 mL of chloroform in a centrifuge tube. The mixture was then centrifuged to separate into (1) an upper insoluble fraction, (2) a soluble fraction, and (3) a precipitated insoluble fraction.

[0253] In the insoluble component of the upper layer (1), in addition to the ABS gel rubber, thermoplastic resins such as polyolefin and polyamide which are insoluble in chloroform are separated.

[0254] The matrix component of the ABS resin is mainly separated from the above-mentioned (2) soluble component.

[0255] The insoluble components in the above-mentioned (3) precipitation are separated mainly in the form of inorganic matter.

[0256] After necessary pretreatment, each of these separated components is subjected to identification and quantification of impurity components using ATR-IR spectroscopy and 1H-NMR, using an internal standard substance as needed.

[0257] In this way, information on the purity and impurity content of the ABS resin is obtained.

[0258] Table 1 below shows the properties (purity, impurities, melt flow rate) of various ABS-based resins.

[0259] [Table 1]

[0260]

[0261] [Hydrogenated block copolymer (x)]

[0262] Regarding the hydrogenated block copolymer (x), only the following hydrogenated block copolymer (b*)-1 was produced by the Production Example shown below.

[0263] As other hydrogenated block copolymers (b*)-2 to (b*)-4 and (b)-5 to (b)-7, various brands of Tuftec (registered trademark) and Asaprene (registered trademark) manufactured and sold by Asahi Kasei Corporation were used.

[0264] The melt flow rate of the hydrogenated block copolymer (x) was measured in accordance with ISO 1133 under the conditions of a temperature of 230° C. and a load of 2.16 kgf.

[0265] The actual hydrogenation rate (mol %) of each product of Tuftec (registered trademark) and Asaprene (registered trademark) is shown as 30 or more (selective hydrogenation) in Table 2 below.

[0266] It is difficult to achieve an actual hydrogenation rate of 100 mol% even for a completely hydrided product, so the hydrogenation rate was 97 mol% as an actual measured value.

[0267] (Manufacturing of Hydrogenation Catalyst)

[0268] The hydrogenation catalyst was prepared as follows.

[0269] In a nitrogen-purged reaction vessel, 1 L of dried and purified cyclohexane was added, 100 mmol of bis(cyclopentadienyl)titanium dichloride was added, and a n-hexane solution containing 200 mmol of trimethylaluminum was added while stirring thoroughly. The mixture was reacted at room temperature for about 3 days to obtain a hydrogenation catalyst.

[0270] (Production of Hydrogenated Block Copolymer)

[0271] The following hydrogenated block copolymer (b*)-1 was produced according to the following Production Example.

[0272] <Production Example: Hydrogenated Block Copolymer (b*)-1>

[0273] A jacketed tank reactor was used, a predetermined amount of cyclohexane was added, and the temperature inside the reactor was adjusted to 65° C. under a nitrogen atmosphere.

[0274] Next, 0.17 parts by mass of n-butyllithium and 0.30 parts by mass of tetramethylmethylenediamine were added.

[0275] Next, a cyclohexane solution containing 20 parts by mass of styrene at a concentration of 25% by mass was supplied to the reactor over a period of about 10 minutes, and the reaction was continued for 15 minutes after the supply.

[0276] Next, a cyclohexane solution containing 58 parts by mass of 1.3-butadiene and 22 parts by mass of styrene at a concentration of 25% by mass was supplied to the reactor over 30 minutes.

[0277] After the reaction, the reaction was continued for 10 minutes while the temperature in the reactor was adjusted to 65°C.

[0278] Next, 0.2 equivalents of tetraglycidyl-1,3-bisaminomethylcyclohexane (CAS No.: 65992-66-7, molecular weight: 366.5) as a coupling agent were added relative to n-butyllithium, and the mixture was reacted at 80° C. for 5 minutes.

[0279] Thereafter, in order to completely stop the polymerization, 0.4 equivalents of ethanol relative to n-butyllithium were added to the reactor to stop the polymerization reaction.

[0280] Next, 80 ppm of the hydrogenation catalyst as titanium per 100 parts by mass of the polymer was added to the obtained polymer solution, and a hydrogenation reaction was carried out under the conditions of a hydrogen pressure of 0.5 MPa and a temperature of 75° C. The hydrogenation rate was adjusted by adjusting the amount of hydrogen supplied to the reactor.

[0281] After the hydrogenation reaction was completed, 0.25 parts by mass of octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate was added as an antioxidant based on 100 parts by mass of the block copolymer.

[0282] Next, the polymer solution concentrated to a certain extent by heating and reducing pressure was supplied to a twin-screw extruder equipped with a degassing function and recovered as a hydrogenated block copolymer (b*)-1.

[0283] The hydrogenated block copolymer (b*)-1 thus obtained had a styrene content of 42% by mass, a butadiene content of 58% by mass, and a hydrogenation rate of 75 mol%.

[0284] The hydrogenated block copolymer (b*)-1 is a mixture of an S1-S / B1 structure and a (S1-S / B1)X structure produced by coupling the S1-S / B1 structure. Molecular weight measurement by GPC, described later, revealed a block copolymer having two peak molecular weights: a weight-average molecular weight of 46,000 for the S1-S / B1 structure and a weight-average molecular weight of 157,000 for the (S1-S / B1)X structure.

[0285] The molecular weight ratio is 157,000 ÷ 46,000 = approximately 3.4. The tetraglycidyl-1,3-bisaminomethylcyclohexane used as the coupling agent has four epoxy groups per molecule, so the difference from the molecular weight ratio, i.e., the average number of coupling agent residues of 0.6, suggests that it contains epoxy groups containing oxygen atoms as heteroatoms.

[0286] The hydrogenated block copolymer (b*)-1 is a modified hydrogenated block copolymer having an epoxy group as a functional group in the coupling agent residue.

[0287] The concentration of the coupling agent containing a functional group in the modified hydrogenated block copolymer (b*)-1 was about 0.15% calculated based on the molecular weight.

[0288] Table 2 below shows the properties of each hydrogenated block copolymer (type of heteroatoms contained, type of functional groups containing the heteroatoms, styrene content, butadiene content, hydrogenation rate (for Tuftec and Asaprene products, whether fully hydrogenated or selectively hydrogenated), weight-average molecular weight, peak molecular weight, number of molecular weight peaks, and melt flow rate).

[0289]

[0290] (Molecular weight determination based on GPC)

[0291] The GPC apparatus and measurement conditions used in the Examples are as follows.

[0292] GPC equipment: HLC-8420 manufactured by Tosoh Corporation

[0293] Column: Four TSKgel SuperHZM-N manufactured by Tosoh Corporation connected in series

[0294] Column temperature: 40°C

[0295] Liquid delivery volume: 0.6mL / min

[0296] Detector: Refractometer (RI)

[0297] Solvent: tetrahydrofuran

[0298] In preparation of a sample for GPC measurement, about 10 mg of a target polymer for molecular weight measurement was dissolved in 20 mL of tetrahydrofuran, and the mixture was filtered to remove insoluble components to obtain a sample.

[0299] The assay method is as follows.

[0300] First, a calibration curve was created using nine different standard polystyrene samples of known molecular weight. The highest molecular weight standard polystyrene had a weight-average molecular weight (Mw) of 1,090,000, and the lowest molecular weight standard polystyrene had a weight-average molecular weight (Mw) of 1,050. Next, using each block polymer whose molecular weight was to be measured, measurement samples were prepared according to the above procedure.

[0301] After confirming that the temperature in the tank containing the column has reached a constant level, the solution sample is injected and the measurement is started. After the measurement is terminated, the obtained molecular weight distribution curve is statistically processed to calculate the weight average molecular weight (Mw) and number average molecular weight (Mn). The molecular weight distribution (Mw / Mn) is the value obtained by dividing the obtained weight average molecular weight (Mw) by the number average molecular weight (Mn). In addition, the peak molecular weight and the number of molecular weight peaks are determined from the above molecular weight distribution curve.

[0302] [Production of Recycled ABS Resin Composition]

[0303] A recycled ABS resin composition was produced by the following method using the recycled ABS resins (a)-1 and 2 shown in Table 1, Polylac PA-757 as the virgin ABS resin (a*)-3, and the hydrogenated block copolymers (b*)-1 to 4 and (b)-5 to 7 shown in Table 2.

[0304] The following equipment was used for the production.

[0305] Twin-screw extruder TEX-30αII manufactured by Japan Steel Works

[0306] Screw diameter 30mm, L / D=36

[0307] First, since the recycled ABS resin (a) is amorphous and is a mixture of white, black, gray, etc. after coarse pulverization without any other treatment, it is homogenized and pelletized using the above-mentioned twin-screw extruder.

[0308] The homogenized recycled ABS resin (a) thus obtained was dry-blended with the respective components: virgin ABS resin (a*), hydrogenated block copolymer (b), and (b*) in the composition ratios described in the following table in the form of pellets at room temperature, and then melt-kneaded using the aforementioned twin-screw extruder.

[0309] The barrel temperature was set to 220°C.

[0310] The pellets of the recycled ABS resin composition were obtained by a strand cutting method.

[0311] [Characteristics of recycled ABS resin composition]

[0312] The following evaluations were performed on various properties of the ABS resin compositions of the Examples and Comparative Examples.

[0313] (mechanical properties)

[0314] <Making Various Test Pieces Using an Injection Molding Machine>

[0315] In the tensile test, the bending test, and the Charpy impact strength test, test pieces were produced using an ISO test piece mold with the following molding machine.

[0316] Injection molding machine: FNX110III hybrid type manufactured by Nissei Plastic Industry Co., Ltd.

[0317] Clamping pressure: 110 tons, barrel temperature: 230°C, mold temperature: 60°C

[0318] The test pieces for measurement in each test were injection-molded and then cured for 24 hours in a constant temperature chamber at a room temperature of 23° C. and a humidity of 50%. Thereafter, various property evaluations were performed.

[0319] <Evaluation Standards and Conditions for Mechanical Properties>

[0320] The details of the evaluation conditions for each mechanical property are as follows.

[0321] The values in the table are the average values of each n number.

[0322] Tensile test: Using a tensile compression tester TG-5kN manufactured by Minebea, the test was conducted at a tensile speed of 50 mm / min in a constant temperature room at 23°C with an n number of 6 in accordance with ISO 527-1.

[0323] Bending test: Using a tension-compression tester TG-5kN manufactured by Minebea, the test was conducted at a compression rate of 2 mm / min in a constant temperature room at 23°C with an n number of 4 in accordance with ISO 178.

[0324] Charpy impact test: According to ISO 179, both a notched Charpy impact test and an unnotched Charpy impact test were conducted in a constant temperature chamber at 23°C with an n number of 10. If the test piece did not break into two or more pieces after the test, it was recorded as NB.

[0325] [Reference Examples 1 to 3, Examples 1 to 28, Comparative Examples 1 to 16]

[0326] Various recycled ABS resin compositions were obtained by combining the recycled ABS resin (a) shown in Table 1 with, if necessary, virgin ABS resin (a*), and combining various unmodified hydrogenated block copolymers (b) and modified hydrogenated block copolymers (b*) shown in Table 2.

[0327] Next, various test pieces were molded using the aforementioned injection molding machine. During injection molding, pre-drying was performed at 90° C. for 2 hours.

[0328] The composition ratios and physical property evaluations of the recycled ABS resin compositions obtained in each example are shown below.

[0329] Tables 3 to 6.

[0330]

[0331]

[0332]

[0333]

[0334] The physical property values shown in Reference Examples 1 and 3 were obtained by the present inventors by evaluating the recycled ABS resin (a)-1 from automobiles and the recycled ABS resin (a)-2 from home appliances.

[0335] The physical property values shown in Reference Example 2 are obtained by evaluating the present inventors using Polylac PA-757 used alone as the virgin ABS resin (a*)-3.

[0336] In order to improve the evaluation accuracy, the product catalog values of virgin ABS resin were not referred to, and the evaluation was performed simultaneously in parallel using the same evaluation equipment as in each example.

[0337] Comparing the results of Reference Examples 1 to 3, it can be seen that the virgin ABS resin (a*)-3 is superior in terms of the balance of mechanical properties such as rigidity and impact strength.

[0338] Recycled ABS resins not only contain foreign resins and foreign matter but also suffer significant degradation in physical properties due to aging. Therefore, it is difficult to reuse recycled ABS resin alone. Even if it is reused, its uses are greatly limited.

[0339] Furthermore, the results of the Examples in Tables 3 to 6 confirmed that the properties can be improved by blending the modified hydrogenated block copolymer (b*) containing a heteroatom as the hydrogenated block copolymer (x) with the recycled ABS resin (a).

[0340] Among the modified hydrogenated block copolymers (b*), the use of epoxy-modified hydrogenated block copolymers derived from coupling agent residues and terminal secondary amine-modified hydrogenated block copolymers demonstrated a more significant modification effect than the use of maleic anhydride-modified hydrogenated block copolymers. This is clearly evident from a comparison of Example 4 with Examples 6 and 8 in Table 3.

[0341] Furthermore, it was confirmed that even with the addition of 1% by mass of the modified hydrogenated block copolymer (b*) in the recycled ABS resin composition, a property improvement effect was achieved. This is clearly evident from the fact that Example 9, shown in Table 4, achieved practically good physical property values. Example 9 used a hydrogenated block copolymer modified with a terminal secondary amine. Even with a relatively small amount of this modified hydrogenated block copolymer (b*), the property balance was well-balanced compared to Reference Example 1, which used only the recycled ABS resin (a), clearly demonstrating a property improvement effect. This indicates that when a hydrogenated block copolymer modified with a terminal secondary amine is added, the secondary amino group contributes significantly to the improvement of the physical properties of the recycled ABS resin composition.

[0342] Furthermore, even when the modified hydrogenated block copolymer (b*) was added at 20% by mass in the recycled ABS resin composition, which is the upper limit of the present invention, a modification effect was achieved. This is clearly evident from the fact that Example 10 in Table 4 achieved practically good physical property values.

[0343] However, considering that the added amount was as high as 20% by mass in the recycled ABS resin composition, no commensurate property-improving effect was observed. In Example 10, the flexural modulus was low, and this flexural modulus tended to decrease in proportion to the added amount of the modified hydrogenated block copolymer (b*). Therefore, it is clear that adding the modified hydrogenated block copolymer (b*) in an amount exceeding 20% by mass in the recycled ABS resin composition has little advantage.

[0344] On the other hand, it is clear that even when the unmodified hydrogenated block copolymer (b) containing no heteroatoms is blended into the recycled ABS resin (a), no modification effect is achieved, and the Charpy impact strength decreases compared to the recycled ABS resin alone. Increasing the blending amount further decreases the Charpy impact strength (unnotched). This is clearly evident from the fact that the property balance of Comparative Examples 1 to 6 in Table 3 is inferior to that of Reference Example 1, and that the property balance of Comparative Examples 9 to 14 in Table 5 is inferior to that of Reference Example 3. Increasing the blending amount of the unmodified hydrogenated block copolymer (b) decreases the Charpy impact strength.

[0345] Furthermore, it is clear that the modified hydrogenated block copolymer (b*) can also exhibit a modification effect by using it in combination with the unmodified hydrogenated block copolymer (b), but when the same amount of hydrogenated block copolymer is added, a higher modification effect is achieved when the total amount is the modified hydrogenated block copolymer (b*). This is also clearly evident from the fact that the property balance of Examples 25 to 28 is better than that of Examples 23 and 24 in Table 6.

[0346] In Comparative Examples 7 and 8 in Table 4, and Comparative Examples 15 and 16 in Table 6, virgin ABS resin was blended into the recycled ABS resin (a) without blending the hydrogenated block copolymer. While these improved properties compared to the case of using only the recycled ABS resin (a), the improvement was lower than when the same amount of recycled ABS resin was blended with the hydrogenated block copolymer. This is clearly evident from a comparison of Comparative Example 7 with Examples 11-12 and Comparative Example 8 with Examples 13-14 in Table 4. This is also clearly evident from a comparison of Comparative Example 15 with Examples 25-26 and Comparative Example 16 with Examples 27-28 in Table 6.

[0347] It is clear that the recycled ABS resin composition of the present invention exhibits significantly improved impact strength, particularly compared to recycled ABS resin alone. While degradation over time and contamination of foreign matter are observed in recycled resins recovered from the market, it has been confirmed that practical product design is sufficient.

[0348] Industrial Applicability

[0349] The recycled ABS resin composition of the present invention effectively utilizes waste plastics, conserves resources, reduces the impact on the global environment, and significantly contributes to achieving carbon neutrality. Furthermore, it significantly contributes to various industries and has industrial applicability as a material for a wide range of molded products using ABS resins, including home appliances, automobiles, and daily necessities.

Claims

1. A recycled ABS resin composition comprising a recycled ABS resin (a) and a hydrogenated block copolymer (x), wherein: The hydrogenated block copolymer (x) is a block copolymer having at least one polymer block S mainly composed of vinyl aromatic monomer units and at least one polymer block B mainly composed of conjugated diene monomer units. At least 30 mol% of the conjugated diene portion constituting the hydrogenated block copolymer (x) is hydrogenated. Regarding the hydrogenated block copolymer (x), The hydrogenated block copolymer (x) contains 30% by mass or more and 100% by mass or less of a modified hydrogenated block copolymer (b*), wherein the modified hydrogenated block copolymer (b*) has at least one molecule of a functional group containing a heteroatom chemically bonded to a polymer graft chain, a polymer terminal, or a coupling agent residue. The mass ratio of the recycled ABS-based resin (a) to the hydrogenated block copolymer (x) is (a) / (x)=99 / 1 to 80 / 20.

2. The recycled ABS resin composition according to claim 1, wherein Further containing virgin ABS resin (a*), The mass ratio of the recycled ABS resin (a) to the virgin ABS resin (a*) is (a) / (a*)=100 / 0 to 20 / 80.

3. The recycled ABS resin composition according to claim 1, wherein In the hydrogenated block copolymer (x), the content of the vinyl aromatic monomer unit is 15% to 50% by mass, and the content of the conjugated diene monomer unit is 85% to 50% by mass.

4. The recycled ABS resin composition according to claim 1, wherein The modified hydrogenated block copolymer (b*) has a functional group on at least one polymer terminal and / or a coupling agent residue.

5. The recycled ABS resin composition according to claim 4, wherein The modified hydrogenated block copolymer (b*) has a functional group at at least one polymer terminal, The functional group is any one selected from the group consisting of a primary amino group, a secondary amino group, and an epoxy group.

6. The recycled ABS resin composition according to claim 1, wherein The recycled ABS resin (a) is recycled from consumer waste and / or industrial waste.

7. The recycled ABS resin composition according to claim 1, wherein The recycled ABS-based resin (a) is a recyclate from a molded article constituting a housing or a mechanism component of any one selected from the group consisting of home appliances, information equipment, communication equipment, and automobiles.

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