Resin composition, molded article and film

Abstract

To provide a resin composition obtained by blending a xylylenediamine-based polyamide resin with a polystyrene resin which has a high maximum tensile strength and high pencil hardness while maintaining transparency inherently possessed by the polystyrene resin and to provide a molded article and a film.SOLUTION: There is provided a resin composition which comprises 85 to 15 pts.mass of a polyamide resin based on 15 to 85 pts.mass of a polystyrene resin and 0.5 to 15 pts.mass of a compatibilizer based on the total 100 pts.mass of the polystyrene resin and the polyamide resin, wherein the polyamide resin is composed of constituent units derived from diamine and constituent units derived from a dicarboxylic acid; 70 mol% or more of the constituent units derived from diamine is derived from xylylenediamine; 70 mol% or more of the constituent units derived from a dicarboxylic acid is derived from α,ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms and isophthalic acid; and 1 to 10 mol% of all the constituent units constituting the polyamide resin is a constituent unit derived from isophthalic acid.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a resin composition, a molded article, and a film, and more particularly to a resin composition using a polystyrene resin and a polyamide resin. [Background technology]

[0002] Polystyrene (PS) resin, which is made from styrene as a raw material monomer, has excellent transparency and is widely used in cassette cases, food containers, household goods, etc. In order to improve its physical properties or to increase its manufacturability, blending it with other resins has been investigated. For example, Patent Document 1 proposes a stretched thermoplastic resin composition consisting of 10 to 98 mass % of a polystyrene-based resin A and 2 to 90 mass % of a polyamide-based resin B, in which the half-crystallization time of the polyamide-based resin measured by a depolarized intensity method is specified to be within a specific range. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-001782 A Summary of the Invention [Problem to be solved by the invention]

[0004] As described above, blending another resin into the polystyrene resin to impart additional functions has been studied. However, blending another resin into the polystyrene resin may result in poor transparency. In particular, the present inventors have investigated blending a xylylenediamine-based polyamide resin in which 70 mol% or more of the diamine-derived structural units are derived from xylylenediamine with a polystyrene resin. However, it is not easy to ensure sufficient transparency in the resulting molded product. Therefore, the present applicant has succeeded in ensuring transparency by modifying a xylylenediamine-based polyamide resin with isophthalic acid. However, depending on the application, there are cases in which a higher maximum tensile strength and a higher pencil hardness are required. The present invention has an object to solve such problems, and to provide a resin composition, a molded article, and a film, which are obtained by blending a polystyrene resin with a xylylenediamine-based polyamide resin, and which have high maximum tensile strength and high pencil hardness while maintaining the excellent transparency inherent to polystyrene resin. [Means for solving the problem]

[0005] In light of the above-mentioned problems, the present inventors have conducted research and have found that the above-mentioned problems can be solved by blending a predetermined amount of a compatibilizer into a resin composition containing a polystyrene resin and a xylylenediamine-based polyamide resin containing a predetermined ratio of structural units derived from isophthalic acid. Specifically, the above problems were solved by the following means. <1> A resin composition comprising: 15 to 85 parts by mass of polystyrene resin, 85 to 15 parts by mass of polyamide resin, and 0.5 to 15 parts by mass of a compatibilizer for a total of 100 parts by mass of the polystyrene resin and the polyamide resin; the polyamide resin is composed of diamine-derived structural units and dicarboxylic acid-derived structural units, 70 mol % or more of the diamine-derived structural units are derived from xylylenediamine, 70 mol % or more of the dicarboxylic acid-derived structural units are derived from an α,ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms and isophthalic acid, and 1 to 10 mol % of all structural units constituting the polyamide resin are structural units derived from isophthalic acid. <2> The polyamide resin is composed of a diamine-derived structural unit and a dicarboxylic acid-derived structural unit, and includes a polyamide resin in which 70 mol % or more of the diamine-derived structural units are derived from xylylenediamine, 85 to 95 mol % or more of the dicarboxylic acid-derived structural units are derived from an α,ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms, and 15 to 5 mol % are derived from isophthalic acid (however, the total does not exceed 100 mol %). <1> The resin composition according to claim 1. <3> the polyamide resin is composed of diamine-derived structural units and dicarboxylic acid-derived structural units, 70 mol % or more of the diamine-derived structural units being derived from xylylenediamine, 40 to 60 mol % of the dicarboxylic acid-derived structural units being derived from an α,ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms, and 60 to 40 mol % being derived from isophthalic acid (however, the total does not exceed 100 mol %); and the polyamide resin is composed of diamine-derived structural units and dicarboxylic acid-derived structural units, 70 mol % or more of the diamine-derived structural units being derived from xylylenediamine, and more than 95 mol % of the dicarboxylic acid-derived structural units being derived from an α,ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms. <1> or <2> The resin composition according to claim 1. <4> The α,ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms is adipic acid. <1> ~ <3> 10. The resin composition according to claim 9 . <5> The compatibilizer contains two or more structural units derived from styrene. <1> ~ <4> 10. The resin composition according to claim 9 . <6> The compatibilizer has a structure capable of reacting with at least one of an amino group and a carboxyl group. <1> ~ <5> 10. The resin composition according to claim 9 . <7> the group reactive with at least one of an amino group and a carboxyl group is at least one selected from an epoxy group, a maleic anhydride group, and an oxazoline group; <6> The resin composition according to claim 1. <8> <1> ~ <7> 2. A molded article formed from the resin composition according to claim 1. <9> <1> ~ <7> 2. A film formed from the resin composition according to claim 1. Effect of the Invention

[0006] The present invention makes it possible to provide a resin composition, a molded article, and a film, which are obtained by blending a polystyrene resin with a xylylenediamine-based polyamide resin, and which have high maximum tensile strength and high pencil hardness while maintaining the excellent transparency inherent to polystyrene resin. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Hereinafter, an embodiment of the present invention (hereinafter, simply referred to as "the present embodiment") will be described in detail. Note that the present embodiment is an example for explaining the present invention, and the present invention is not limited to the present embodiment. In this specification, the use of "to" means that the numerical values ​​before and after it are included as the lower limit and upper limit. In this specification, various physical properties and characteristic values ​​are those at 23° C. unless otherwise specified. In this specification, the term "film" refers to a generally flat molded body having a small thickness relative to its length and width, and is intended to include a sheet.

[0008] The resin composition of the present embodiment contains 85 to 15 parts by mass of polyamide resin per 15 to 85 parts by mass of polystyrene resin, and contains 0.5 to 15 parts by mass of a compatibilizer per 100 parts by mass of the total of the polystyrene resin and the polyamide resin. The polyamide resin is composed of diamine-derived structural units and dicarboxylic acid-derived structural units, 70 mol % or more of the diamine-derived structural units are derived from xylylenediamine, 70 mol % or more of the dicarboxylic acid-derived structural units are derived from an α,ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms and isophthalic acid, and 1 to 10 mol % of all structural units constituting the polyamide resin are isophthalic acid-derived structural units. By adopting such a constitution, it is possible to obtain a resin composition having high maximum tensile strength and high pencil hardness while maintaining the excellent transparency inherent to polystyrene resin, and further, it is possible to obtain a resin composition having excellent chemical resistance.

[0009] In this embodiment, by blending a compatibilizer, a high maximum tensile strength is imparted, and for example, when the resin composition is molded into a film and subjected to a tensile test, tearing in the MD (machine direction, resin flow direction) can be effectively suppressed. This is presumed to be due to the following mechanism. That is, it was presumed that in a mixture of polystyrene resin and xylylenediamine-based polyamide resin, islands formed by components mixed in small amounts are formed in a sea formed by components mixed in large amounts. When the mixing ratio of xylylenediamine-based polyamide resin is low, these islands are derived from xylylenediamine-based polyamide resin. These islands do not cause any problems depending on the application, but for example, when a mixture of polystyrene resin and xylylenediamine-based polyamide resin is extruded with an extruder to form a film, the islands of xylylenediamine-based polyamide resin are stretched in the MD and become streaky, which was presumed to cause the film to tear. In this embodiment, it is presumed that the compatibility between the polystyrene resin and the xylylenediamine-based polyamide resin is increased by adding a compatibilizer to the mixture of the polystyrene resin and the xylylenediamine-based polyamide resin, or that the xylylenediamine-based polyamide resin is finely dispersed in the styrene resin, thereby reducing the number of streaky islands and effectively suppressing cracking during the tensile test. Also, even when the mixing ratio of the polystyrene resin is low or the same amount as the xylylenediamine-based polyamide resin, it is presumed that the cracking during the tensile test can be effectively suppressed for the above reasons.

[0010] <Polystyrene resin> The resin composition of the present embodiment contains a polystyrene resin. By containing a polystyrene resin, a resin composition having high transparency can be obtained. The polystyrene resin used in the resin composition of this embodiment can be a wide variety of resins that are generally used for this type of resin. Examples of polystyrene resins include homopolymers of styrene-based monomers and copolymers of styrene-based monomers with other monomers that can be copolymerized with them, and homopolymers of styrene-based monomers are preferred. In this embodiment, the homopolymer of a styrene-based monomer refers to a polystyrene resin in which 80% by mass or more (preferably 90% by mass or more, more preferably 95% by mass or more) of the monomers constituting the polystyrene resin are styrene-based monomers (preferably styrene). In addition, the polystyrene resin used in the resin composition of the present embodiment preferably does not contain a functional group.

[0011] Examples of the styrene-based monomer include alkyl-substituted styrenes such as styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-ethylstyrene, 4-t-butylstyrene, and 2,4-dimethylstyrene (preferably styrene substituted with an alkyl group having 1 to 3 carbon atoms), α-alkyl-substituted styrenes such as α-methylstyrene and α-methyl-4-methylstyrene, halogenated styrenes such as chlorostyrene and bromostyrene, halogen-substituted alkylstyrenes, polyalkoxystyrenes, polycarboxyalkylstyrenes, polyalkyletherstyrenes, and polyalkylsilylstyrenes, with styrene being preferred.

[0012] Examples of other monomers copolymerizable with styrene monomers include (meth)acrylic monomers, such as acrylic acid or methacrylic acid, methyl acrylate or methyl methacrylate, ethyl acrylate or ethyl methacrylate, butyl acrylate or butyl methacrylate, 2-ethylhexyl acrylate or 2-ethylhexyl methacrylate, and other acrylic acid or methacrylic acid esters.

[0013] The polystyrene resin may also be impact-resistant polystyrene, styrene-conjugated diene block copolymer, hydrogenated styrene-conjugated diene block copolymer, ABS (rubber graft styrene-acrylonitrile copolymer), MBS (rubber graft styrene-methyl methacrylate copolymer), rubber graft styrene-(meth)acrylic acid ester copolymer, etc. However, it is preferable that the polystyrene resin used in this embodiment is not a so-called elastomer (impact resistance improver).

[0014] The polystyrene resin used in this embodiment is intended to exclude those equivalent to a compatibilizer, which will be described later.

[0015] The method for synthesizing polystyrene resin is not particularly limited, and a general method can be adopted. For example, polystyrene resin can be obtained by radical polymerization of styrene using benzoyl peroxide as an initiator (radical initiator). The polystyrene obtained in this case usually has an atactic structure. Atactic polystyrene is a thermoplastic resin, is inexpensive, and can be suitably adopted due to advantages such as easy injection molding. Alternatively, recycled polystyrene resin may be used in consideration of the environment.

[0016] The polystyrene resin used in the present embodiment has a refractive index of preferably 1.55 or more, more preferably 1.56 or more, even more preferably 1.57 or more, and even more preferably 1.58 or more. The upper limit of the refractive index is preferably 1.60 or less.

[0017] The molecular weight of the polystyrene resin is preferably more than 80,000, more preferably more than 100,000, even more preferably 150,000 or more, more preferably 180,000 or more, and even more preferably 200,000 or more, as measured by GPC (gel permeation chromatography) method, and the upper limit is preferably 1,000,000 or less, more preferably 800,000 or less, and even more preferably 500,000 or less.

[0018] The content of the polystyrene resin in the resin composition of the present embodiment may be determined as appropriate, but is preferably 15% by mass or more and 85% by mass or less in the resin composition. The resin composition of the present embodiment may contain only one type of polystyrene, or may contain two or more types. When two or more types are contained, the total amount is preferably in the above range.

[0019] <Polyamide resin> The resin composition of the present embodiment is composed of a diamine-derived structural unit and a dicarboxylic acid-derived structural unit, and includes a polyamide resin in which 70 mol % or more of the diamine-derived structural units are derived from xylylenediamine, and 70 mol % or more of the dicarboxylic acid-derived structural units are derived from α,ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms and isophthalic acid, and 1 to 10 mol % of all structural units constituting the polyamide resin are isophthalic acid-derived structural units (sometimes referred to as "polyamide resin used in the present embodiment" in this specification). By using a xylylenediamine-based polyamide resin containing a certain proportion of isophthalic acid-derived structural units in this way, a resin composition having high pencil hardness can be obtained. In addition, a resin composition having excellent chemical resistance can be obtained.

[0020] In the polyamide resin used in the present embodiment, 70 mol% or more, preferably 80 mol% or more, more preferably 90 mol% or more, even more preferably 95 mol% or more, and even more preferably 99 mol% or more of the diamine-derived structural units are derived from xylylenediamine. The upper limit is 100 mol%. The xylylenediamine is preferably meta-xylylenediamine and / or para-xylylenediamine, and more preferably meta-xylylenediamine, for preferably 80 mol% or more, more preferably 90 mol% or more, even more preferably 95 mol% or more, and even more preferably 99 mol% or more of the xylylenediamine.

[0021] Examples of diamines other than xylylenediamine include aromatic diamines such as paraphenylenediamine, and aliphatic diamines such as 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, octamethylenediamine, nonamethylenediamine, etc. These other diamines may be used alone or in combination of two or more kinds.

[0022] In the polyamide resin used in the present embodiment, 70 mol % or more, preferably 80 mol % or more, more preferably 90 mol % or more, even more preferably 95 mol % or more, and even more preferably 99 mol % or more of the dicarboxylic acid-derived structural units are derived from α,ω-straight-chain aliphatic dicarboxylic acids having 4 to 20 carbon atoms and isophthalic acid. The upper limit is 100 mol %. In other words, 70 mol % or more of the dicarboxylic acid-derived structural units are composed of structural units derived from α,ω-straight-chain aliphatic dicarboxylic acids having 4 to 20 carbon atoms and structural units derived from isophthalic acid.

[0023] Examples of the α,ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms include aliphatic dicarboxylic acids such as succinic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, adipic acid, sebacic acid, undecanedioic acid, and dodecanedioic acid, and adipic acid is preferred, with adipic acid being more preferred. The α,ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms may be one type or two or more types.

[0024] The dicarboxylic acid-derived structural unit may contain a dicarboxylic acid other than isophthalic acid and an α,ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms. Examples of the other dicarboxylic acid include phthalic acid compounds such as terephthalic acid and orthophthalic acid, and naphthalene dicarboxylic acid compounds such as 1,2-naphthalene dicarboxylic acid, 1,3-naphthalene dicarboxylic acid, 1,4-naphthalene dicarboxylic acid, 1,5-naphthalene dicarboxylic acid, 1,6-naphthalene dicarboxylic acid, 1,7-naphthalene dicarboxylic acid, 1,8-naphthalene dicarboxylic acid, 2,3-naphthalene dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, and 2,7-naphthalene dicarboxylic acid, and these may be used alone or in combination of two or more.

[0025] The polyamide resin used in this embodiment has 1 to 10 mol% of isophthalic acid-derived structural units among all structural units constituting the polyamide resin. By making the isophthalic acid-derived structural units equal to or more than the lower limit and equal to or less than the upper limit, the refractive index of the polyamide resin becomes close to that of the styrene resin, and the high light transmittance inherent to the styrene resin can be maintained at a high level. Furthermore, a resin composition having excellent transparency and low haze can be obtained. Here, the total structural units constituting the polyamide resin may include, in addition to structural units derived from diamines and structural units derived from dicarboxylic acids, terminal groups, and other structural units within the scope of the present invention. Examples of other structural units include structural units derived from lactams such as ε-caprolactam, valerolactam, laurolactam, and undecalactam, and structural units derived from aminocarboxylic acids such as 11-aminoundecanoic acid and 12-aminododecanoic acid. Furthermore, the polyamide resin used in this embodiment is generally composed of structural units derived from dicarboxylic acids and structural units derived from diamines, with 95% by mass or more, preferably 98% by mass or more, and more preferably 99% by mass or more of the structural units excluding the terminal groups. The proportion of the isophthalic acid-derived structural units in the total structural units constituting the polyamide resin used in this embodiment is preferably 1.5 mol% or more, more preferably 2.0 mol% or more, and even more preferably 2.3 mol% or more. The upper limit of the proportion of the isophthalic acid-derived structural units is preferably 9.5 mol% or less, more preferably 9.0 mol% or less, even more preferably 8.5 mol% or less, even more preferably 8.0 mol% or less, and even more preferably 7.7 mol% or less.

[0026] The polyamide resin used in the present embodiment may be composed of one type of polyamide resin, or may be composed of two or more types of polyamide resin. That is, only one type of polyamide resin may be used in which the isophthalic acid modification rate is 1 to 10 mol% of all the structural units constituting the polyamide resin (hereinafter referred to as "polyamide resin type (B)"). Alternatively, a polyamide resin having a high isophthalic acid modification rate may be blended with a polyamide resin having a low isophthalic acid modification rate or not modified with isophthalic acid, so that the isophthalic acid modification rate in the polyamide resin is adjusted to 1 to 10 mol% (hereinafter referred to as "polyamide resin type (C)". Furthermore, polyamide resin type (B) and polyamide resin type (C) may be blended. Polyamide resin form (B) and polyamide resin form (C) will be described in detail below, but matters not specifically mentioned below will be appropriately determined based on the contents described above, and the preferred ranges are the same.

[0027] Next, the polyamide resin form (B) will be described. In the polyamide resin type (B), the polyamide resin is composed of diamine-derived structural units and dicarboxylic acid-derived structural units, and it is preferred that 70 mol % or more of the diamine-derived structural units are derived from xylylenediamine, 85 to 95 mol % or more of the dicarboxylic acid-derived structural units are derived from an α,ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms (preferably adipic acid), and 15 to 5 mol % are derived from isophthalic acid (however, the total does not exceed 100 mol %).

[0028] In the polyamide resin type (B), the proportion of structural units derived from an α,ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms in the structural units derived from a dicarboxylic acid is preferably 87 mol % or more, more preferably 89 mol % or more, and is preferably 93 mol % or less, more preferably 91 mol % or less.

[0029] In the polyamide resin type (B), the proportion of the constituent units derived from isophthalic acid in the constituent units derived from dicarboxylic acid is preferably 7 mol % or more, and is preferably 13 mol % or less, and more preferably 11 mol % or less.

[0030] Next, the polyamide resin form (C) will be described. In the polyamide resin form (C), the polyamide resin is preferably a polyamide resin (hereinafter sometimes referred to as "high isophthalic acid modified polyamide resin (C-1)") that is composed of diamine-derived structural units and dicarboxylic acid-derived structural units, in which 70 mol% or more of the diamine-derived structural units are derived from xylylenediamine, 40 to 60 mol% of the dicarboxylic acid-derived structural units are derived from an α,ω-straight-chain aliphatic dicarboxylic acid having 4 to 20 carbon atoms (preferably adipic acid), and 60 to 40 mol% are derived from isophthalic acid (however, the total does not exceed 100 mol%), and a polyamide resin (hereinafter sometimes referred to as "low / no isophthalic acid modified polyamide resin (C-2)") that is composed of diamine-derived structural units and dicarboxylic acid-derived structural units, in which 70 mol% or more of the diamine-derived structural units are derived from xylylenediamine, and more than 95 mol% of the dicarboxylic acid-derived structural units are derived from an α,ω-straight-chain aliphatic dicarboxylic acid having 4 to 20 carbon atoms (preferably adipic acid).

[0031] The highly isophthalic acid modified polyamide resin (C-1) is composed of diamine-derived structural units and dicarboxylic acid-derived structural units, with 70 mol % or more of the diamine-derived structural units being derived from xylylenediamine, and 40 to 60 mol % of the dicarboxylic acid-derived structural units being derived from an α,ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms, and 60 to 40 mol % being derived from isophthalic acid (however, the total does not exceed 100 mol %). In the high isophthalic acid modified polyamide resin (C-1), the proportion of structural units derived from α,ω-linear aliphatic dicarboxylic acids having 4 to 20 carbon atoms in the structural units derived from dicarboxylic acids is 40 to 60 mol %, preferably 45 mol % or more, and preferably 55 mol % or less. In the highly isophthalic acid modified polyamide resin (C-1), the proportion of structural units derived from isophthalic acid in the structural units derived from dicarboxylic acids is 60 to 40 mol %, preferably 45 mol % or more, and preferably 55 mol % or less.

[0032] The low / non-isophthalic acid modified polyamide resin (C-2) is composed of diamine-derived structural units and dicarboxylic acid-derived structural units, with 70 mol % or more of the diamine-derived structural units being derived from xylylenediamine, and more than 95 mol % of the dicarboxylic acid-derived structural units being derived from α,ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms. In the low / non-isophthalic acid modified polyamide resin (C-2), the proportion of α,ω-linear aliphatic dicarboxylic acids having 4 to 20 carbon atoms in the dicarboxylic acid-derived structural units is preferably 97 mol % or more, more preferably 99 mol % or more, and may be 100 mol %.

[0033] The content of the polyamide resin used in the resin composition of the present embodiment may be determined appropriately, but is preferably 15% by mass or more and 85% by mass or less in the resin composition. The resin composition of the present embodiment may contain only one type of polyamide resin used in the present embodiment, or may contain two or more types. When two or more types are contained, the total amount is preferably in the above range.

[0034] <Blend form of polystyrene resin and polyamide resin> Next, the blend form of the polystyrene resin and the polyamide resin will be described. The resin composition of the present embodiment contains 15 to 85 parts by mass (preferably 18 to 82 parts by mass) of polystyrene resin and 85 to 15 parts by mass (preferably 82 to 18 parts by mass) of polyamide resin used in the present embodiment. The total of the polystyrene resin and the polyamide resin is 100 parts by mass. In particular, the resin composition of the present embodiment can achieve high light transmittance even when the proportion of the polyamide resin used in the present embodiment is high, for example, when the resin composition contains 85 to 75 parts by mass of the polyamide resin used in the present embodiment per 15 to 25 parts by mass of polystyrene resin. Furthermore, when the resin composition of the present embodiment contains 15 to 25 parts by mass of the polyamide resin used in the present embodiment with respect to 85 to 75 parts by mass of the polystyrene resin, a resin composition having excellent and well-balanced properties can be obtained.

[0035] <Compatibilizer> The resin composition of the present embodiment contains a compatibilizer. By containing the compatibilizer, the compatibility between the polystyrene resin and the polyamide resin used in the present embodiment is improved, and a resin composition excellent in maximum tensile strength can be obtained while maintaining the high transparency inherent to the polystyrene resin. The type of the compatibilizer is not particularly limited as long as it improves the compatibility of the polystyrene resin and the polyamide resin used in the present embodiment and makes them easier to mix, and may be any of low molecular weight compounds, oligomers, and polymers.Specific examples include compatibilizers having both a structure that interacts with the polystyrene resin and a structure that interacts with the polyamide resin used in the present embodiment.The "interaction" here refers to a structure that is compatible with the resin and a structure that reacts with the resin.

[0036] The compatibilizer used in this embodiment preferably contains two or more structural units derived from styrene. By containing structural units derived from styrene, compatibility with polystyrene resin tends to be further improved. The compatibilizer used in this embodiment is preferably a polymer containing two or more structural units derived from styrene (preferably 2 or more, more preferably 10 or more, and also preferably 1250 or less, more preferably 800 or less, further 680 or less, and may be 120 or less).

[0037] The compatibilizer used in this embodiment preferably has a structure that reacts with at least one of an amino group and a carboxyl group. Such a structure reacts with the terminal carboxyl group or the terminal amino group of the polyamide resin used in this embodiment. That is, the compatibilizer is suitable as a structure that acts with the polyamide resin. Examples of the structure that reacts with at least one of an amino group and a carboxyl group include at least one selected from an epoxy group, a maleic anhydride group, and an oxazoline group, and a maleic anhydride group and / or an oxazoline group are preferred. The compatibilizer used in the present embodiment may have a structure that is compatible with the polyamide resin used in the present embodiment. Examples of the structure that is compatible with the polyamide resin include a compatibilizer that partially contains a polyamide structure, such as a resin partially modified with polyamide.

[0038] The compatibilizer used in the present embodiment is preferably a polymer, more preferably a polymer having a weight average molecular weight of 5000 to 180,000 (preferably 5,000 to 80,000) in terms of polystyrene measured by GPC (gel permeation chromatography). The compatibilizer used in the present embodiment preferably has a glass transition temperature of 45 to 180° C. as measured by differential scanning calorimetry (DSC).

[0039] Specific examples of the compatibilizer used in this embodiment include the following (1) and (2), with (1) being preferred. (1) A compatibilizer that contains two or more structural units derived from styrene and has a structure that reacts with at least one of an amino group and a carboxyl group. (2) A compatibilizer that contains two or more structural units derived from styrene and has a structure that is compatible with polyamide resin.

[0040] Further specific examples of the compatibilizer (1) include the following, with (1-1) being preferred. (1-1) A compatibilizer having a polystyrene backbone and a structure that reacts with at least one of an amino group and a carboxyl group (preferably at least one selected from an epoxy group, a maleic anhydride group, and an oxazoline group, more preferably a maleic anhydride group and / or an oxazoline group) (1-2) A compatibilizer which is a styrene-acrylic copolymer and has a structure which reacts with at least one of an amino group and a carboxyl group (preferably at least one selected from an epoxy group, a maleic anhydride group, and an oxazoline group, more preferably a maleic anhydride group and / or an oxazoline group).

[0041] Further specific examples of the compatibilizer (2) include the following. (2-1) A compatibilizer which is a polyamide-modified polystyrene polymer (2-2) A compatibilizer that is a polyamide-modified styrene-acrylic copolymer

[0042] The resin composition of the present embodiment contains 0.5 parts by mass or more of the compatibilizer relative to 100 parts by mass of the total of the polystyrene resin and the polyamide resin, preferably 0.7 parts by mass or more, more preferably 0.9 parts by mass or more, even more preferably 1.1 parts by mass or more, even more preferably 3 parts by mass or more, and even more preferably 4 parts by mass or more. By making it equal to or more than the lower limit, the effect as a compatibilizer is effectively exerted. In addition, the content of the compatibilizer is 15 parts by mass or less, preferably 12 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 9 parts by mass or less. By making it equal to or less than the upper limit, it is possible to maintain a higher level of pencil hardness and chemical resistance. The resin composition of the present embodiment may contain only one type of compatibilizer, or may contain two or more types. When two or more types are contained, the total amount is preferably in the above range.

[0043] <Other ingredients> The resin composition of the present embodiment may consist of only the polystyrene resin, the polyamide resin used in the present embodiment, and the compatibilizer, or may contain other components. In the resin composition of this embodiment, the components other than the polystyrene resin, the polyamide resin used in this embodiment, and the compatibilizer include additives such as polyamide resins other than the polyamide resin used in this embodiment, thermoplastic resins other than polyamide resins, lubricants, fillers, delusterants, heat stabilizers, weather stabilizers, ultraviolet absorbers, plasticizers, flame retardants, antistatic agents, color inhibitors, crystallization nucleating agents, and gelation inhibitors, which can be added as necessary. Each of these additives may be one type or two or more types.

[0044] Examples of other polyamide resins include polyamide 6, polyamide 66, polyamide 46, polyamide 6 / 66 (a copolymer consisting of a polyamide 6 component and a polyamide 66 component), polyamide 610, polyamide 612, polyamide 11, polyamide 12, polyamide 6I, polyamide 6T, polyamide 9I, polyamide 9T, polyamide 10T, polyamide 6I / 6T, polyamide 9I / 9T, etc. These other polyamide resins may each be one type or two or more types.

[0045] Examples of thermoplastic resins other than polyamide resins include polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and polybutylene naphthalate, polystyrene resins, acrylic resins, etc. These thermoplastic resins other than polyamide resins may each be one type or two or more types.

[0046] In the resin composition of the present embodiment, the total content of the polystyrene resin, the polyamide resin used in the present embodiment, and the compatibilizer is preferably 85% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and even more preferably 97% by mass or more, and may be 99% by mass or more. The upper limit may be 100% by mass or less.

[0047] <Method of producing resin composition> The resin composition of the present embodiment can be produced by a known method. For example, it can be obtained by melt-kneading a polystyrene resin, a polyamide resin, and a compatibilizer. In particular, in the production method of the present embodiment, when two or more polyamide resins are used, it is preferable to melt-knead the two or more polyamide resins, and then add the polystyrene resin and the compatibilizer and melt-knead them. When the polystyrene resin, the polyamide resin and the compatibilizer are fed into the extruder, they may be fed all at once or may be fed successively, but it is preferable to feed them all at once.

[0048] <Physical properties of resin composition> The resin composition of the present embodiment preferably has a high light transmittance. Specifically, when the resin composition of the present embodiment is molded into a molded piece having a thickness of 2 mm, the light transmittance is preferably 80% or more, more preferably 83% or more, and even more preferably 85% or more. The upper limit of the light transmittance is ideally 100%, but practically 99% or less. The resin composition of this embodiment preferably maintains the high transparency inherent to polystyrene resins even when a compatibilizer is blended. Specifically, the haze of the resin composition of this embodiment when molded into a molded piece having a thickness of 2 mm is preferably 15% or less, more preferably 10% or less. The lower limit of the haze is preferably as low as possible, but for example, a practical value is a value that is 0.1% or more higher than the haze value of the resin composition of this embodiment, in which the compatibilizer is removed, when the resin composition is molded into a molded piece having a thickness of 2 mm. Also, a specific numerical value is, for example, 3.0% or more. The resin composition of this embodiment preferably has a high maximum tensile strength when made into a film having a length of 11 cm, a width of 15 mm, and a thickness of 100 μm, measured under conditions of a chuck distance of 5 cm and a speed of 20 mm / sec. Specifically, the maximum tensile strength is preferably 15 MPa or more, more preferably 21 MPa or more, and even more preferably 25 MPa or more. There is no particular upper limit for the maximum tensile strength, but it is practical to set it to 50 MPa or less. The resin composition of the present embodiment, when formed into a film having a thickness of 100 μm, preferably has a pencil hardness of F or more, more preferably H or more, and even more preferably 2H or more according to ISO 15184. The upper limit of the pencil hardness is not particularly specified, but 3H or less is practical, and may be 2H or less. The light transmittance, haze, maximum tensile strength and pencil hardness are measured according to the methods described in the examples below.

[0049] <Molded products> The molded article of the present embodiment is formed from the resin composition of the present embodiment. The specific method for producing a molded article using the resin composition of the present embodiment is not particularly limited, and any molding method generally used for thermoplastic resins can be used. Specifically, molding methods such as injection molding, blow molding, extrusion molding, and press molding can be applied.

[0050] Examples of molded articles include films (single-layer films (including single-layer sheets) and multi-layer films (including multi-layer sheets)), fibers, threads, monofilaments, multifilaments, ropes, tubes, hoses, various molding materials, containers, various parts, finished products, housings, and the like. Furthermore, the molded articles (particularly films, monofilaments, and multifilaments) may be stretched. The molded articles may be thin-walled molded articles, hollow molded articles, and the like. Among them, in the present embodiment, from the viewpoint of utilizing the advantage of high transparency, a film (including a sheet) is preferable. The thickness of the film is preferably 1000 μm or less, and more preferably 5 μm or more, and more preferably 10 μm or more. Specific examples of molded articles include, but are not limited to, everyday items such as food packaging films such as wraps and shrink films, pouches of various shapes, container lids, bottles, cups, trays, tubes, transparent parts for display screens of electronic devices, transparent parts for lighting equipment, surface parts for recording media, pharmaceutical packaging parts, transportation equipment parts such as automobiles, general machinery parts, precision machinery parts, office automation equipment parts, building materials and housing-related parts, medical devices, leisure sports goods, play equipment, medical products, etc.

[0051] The fields of use of molded products include, but are not limited to, automobile and other transportation equipment parts, automobile interior parts, general machine parts, precision machine parts, electronic and electrical equipment parts, office equipment parts, building materials and housing related parts, medical equipment, leisure sports goods, play equipment, medical products, food packaging films, decorations, paint and oil containers, defense and aerospace products, etc. EXAMPLES

[0052] The present invention will be described in more detail below with reference to examples. The materials, amounts, ratios, processing contents, processing procedures, etc. shown in the following examples can be appropriately changed without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below. If the measuring instruments used in the examples are difficult to obtain due to discontinuation or the like, measurements can be made using other instruments with equivalent performance.

[0053] 1. Raw materials Polystyrene (A): Made by Nippon Polystyrene, polystyrene pellets, polystyrene homopolymer, GPPS SGP10 Polyamide (B): Polyamide pellets (MXD6I(10)) obtained by Synthesis Example 1 below Polyamide (d): Polyamide pellets (MXD6) obtained by Synthesis Example 2 below Polyamide (e): Polyamide pellets (MXD6I(50)) obtained by Synthesis Example 3 below Polyamide (C)-1:Polyamide (d):Polyamide (e)=90:10 (mass ratio) Polyamide (C)-2:Polyamide (d):Polyamide (e)=80:20 (mass ratio) Polyamide (C)-3:Polyamide (d):Polyamide (e)=70:30 (mass ratio) Compatibilizer (G): Epoxy modified polystyrene, Toagosei Co., Ltd., ARUFON UG-4070, styrene-acrylic resin Compatibilizer (H): Maleic anhydride modified polystyrene, POLYSCOPE POLYMERS, XIBOND 220 Compatibilizer (I): Oxazoline-modified polystyrene, Nippon Shokubai Co., Ltd., Epocross RPS-1005

[0054] <Synthesis Example 1: Synthesis of MXD6I (10)> A precisely weighed amount of 6,000 g (41.1 mol) adipic acid, 758 g (4.6 mol) isophthalic acid (total 45.7 mol, molar ratio of adipic acid to isophthalic acid was 90:10), 1.9 g of sodium hypophosphite monohydrate (NaH2PO2·H2O) (100 ppm by mass in terms of phosphorus atom concentration in polyamide resin), and 0.8 g of sodium acetate were charged into a jacketed 50-L reactor equipped with a stirrer, a partial condenser, a total condenser, a thermometer, a dropping tank, and a nitrogen gas inlet tube, and the inside of the reactor was thoroughly substituted with nitrogen, after which nitrogen was added until the internal pressure reached 0.4 MPa, and the reactor was heated to 190°C while stirring the inside of the reactor under a small amount of nitrogen flow. To this, 6225 g (45.6 mol) of metaxylylenediamine was added dropwise under stirring, and the temperature in the system was continuously raised while removing the generated condensation water from the system. After the dropwise addition of metaxylylenediamine was completed, the internal temperature was raised, and when it reached 255°C, the pressure in the reaction vessel was reduced, and the internal temperature was further raised to 260°C for 10 minutes to continue the melt polycondensation reaction. Thereafter, the system was pressurized with nitrogen, and the obtained polymer was taken out of the strand die, cooled with water, and pelletized to obtain polyamide (MXD6I(10)).

[0055] <Synthesis Example 2 (Synthesis of MXD6)> Into a jacketed 50 L reaction vessel equipped with a stirrer, a partial condenser, a total condenser, a thermometer, a dropping tank, and a nitrogen gas inlet tube, precisely weighed 9000 g (61.6 mol) of adipic acid, 2.6 g of sodium hypophosphite monohydrate (100 ppm by mass in terms of the phosphorus atom concentration in the polyamide resin), and 0.8 g of sodium acetate were charged, thoroughly purged with nitrogen, and further heated to 180° C. while stirring the system under a small amount of nitrogen flow. To this, 8600g (63.2mol) of metaxylylenediamine was added dropwise under stirring, and the temperature in the system was continuously raised while removing the generated condensation water from the system. After the dropwise addition of metaxylylenediamine was completed, the internal temperature was raised, and when it reached 255°C, the pressure in the reaction vessel was reduced, and the internal temperature was further raised to 260°C for 10 minutes to continue the melt polycondensation reaction. Thereafter, the system was pressurized with nitrogen, and the obtained polymer was taken out of the strand die, cooled with water, and pelletized to obtain polyamide (MXD6).

[0056] <Synthesis Example 3 (Synthesis of MXD6I (50)> Precisely weighed 6,000 g (41.1 mol) of adipic acid, 6,820 g (41.1 mol) of isophthalic acid, 3.6 g of sodium hypophosphite monohydrate (NaH2PO2·H2O) (100 ppm by mass in terms of phosphorus atom concentration in polyamide resin), and 1.4 g of sodium acetate were mixed into a 50 L jacketed reactor equipped with a stirrer, a partial condenser, a total condenser, a thermometer, a dropping tank, and a nitrogen gas inlet tube, and the inside of the reactor was thoroughly substituted with nitrogen, after which nitrogen was added until the internal pressure reached 0.4 MPa, and the reactor was heated to 190°C while stirring under a small amount of nitrogen flow. To this, 11,205 g (82.11 mol) of metaxylylenediamine was added dropwise under stirring, and the temperature in the system was continuously raised while removing the generated condensation water from the system. After the dropwise addition of metaxylylenediamine was completed, the internal temperature was raised, and when it reached 255°C, the pressure in the reaction vessel was reduced, and the internal temperature was further raised to 260°C for 10 minutes to continue the melt polycondensation reaction. Thereafter, the system was pressurized with nitrogen, and the obtained polymer was taken out of the strand die, cooled with water, and pelletized to obtain polyamide (MXD6I(50)).

[0057] Examples 1 to 22, Comparative Examples 1 to 3 The polyamide pellets were dried at 130°C for 4 hours, then dry-blended with polystyrene in the mass ratios shown in Tables 1 to 5, and further mixed with a compatibilizer in the mass ratios shown in Tables 1 to 5. The mixture was introduced into an injection molding machine (SE130DU-HP, manufactured by Sumitomo Heavy Industries, Ltd.) to produce molded pieces with thicknesses of 2 mm and 4 mm. Molding was performed at a cylinder temperature of 280°C and a mold surface temperature of 90°C. Similarly, polystyrene, polyamide, and compatibilizer were dry-blended to the mass ratios shown in Tables 1 to 5, and the resulting samples were fed into a single-screw extruder (PTM-30, manufactured by the Plastics Engineering Research Institute) from its base, melted, and extruded to produce a film with a thickness of 100 μm. The temperature of the extruder was set at 260°C. The following evaluations were carried out, and the results are shown in Tables 1 to 5.

[0058] <Light transmittance> The total light transmittance of the obtained molded piece having a thickness of 2 mm was measured in accordance with JIS K7361-1:1997. The color and turbidity simultaneous measuring device used was the "COH400" manufactured by Nippon Denshoku Industries Co., Ltd. The unit is %.

[0059] <HAZE> The haze of the 2 mm thick molded piece obtained above was measured using a color / turbidity simultaneous measuring device. The unit is %. The color and turbidity simultaneous measuring device used was the "COH400" manufactured by Nippon Denshoku Industries Co., Ltd.

[0060] <Maximum tensile strength> The tensile strength of the film obtained above was measured. The above film cut to a length of 11 cm, width of 15 mm, and thickness of 100 μm was measured using a tensile tester (Strograph IIB) at a chuck distance of 5 cm and a pulling speed of 20 mm / sec. Five measurements were taken, and the average maximum tensile strength was used to evaluate the results as follows: S:25MPa or more A: 20MPa or more and less than 25MPa B: 15MPa or more and less than 20MPa C: Less than 15MPa

[0061] <Chemical resistance> The 4 mm thick molded piece obtained above was immersed in toluene at 23°C and left to stand for 5 days, and its appearance was evaluated. The molded piece after immersion was placed on a printed matter. The visibility of the printed image in the background was evaluated visually. Five experts performed the evaluation, and a majority vote was used. The results were categorized and compared as follows: (evaluation) A: There was no change in the shape of the molded piece, and there was no effect on its transparency. B: There was no change in the shape of the molded piece, but the transparency was deteriorated (visible). C: There was no change in the shape of the molded piece, but the transparency was deteriorated (not visible). D: The shape of the molded piece changed and the transparency also deteriorated. Regarding visibility, molded pieces that were cloudy and had no visibility before immersion and had no change in shape were rated C even if there was no change in visibility before and after the chemical resistance test.

[0062] <Pencil hardness> The pencil hardness of the film obtained above was measured in accordance with ISO 15184.

[0063] [Table 1]

[0064] [Table 2]

[0065] [Table 3]

[0066] [Table 4]

[0067] [Table 5]

[0068] In the above Tables 1 to 5, the isophthalic acid modification rate means the proportion (mol %) of structural units derived from isophthalic acid in all structural units constituting the polyamide resin. As is clear from the above results, by using the composition of the present invention, a resin composition excellent in maximum tensile strength and pencil hardness while maintaining the inherent transparency of polystyrene resin was obtained. Furthermore, a resin composition excellent in chemical resistance was obtained. In contrast, when the xylylenediamine-based polyamide resin was not included (Comparative Example 1), the pencil hardness was low, and the chemical resistance was also poor. Furthermore, when the compatibilizer was not included (Comparative Example 2), the maximum tensile strength was poor. When a xylylenediamine-based polyamide resin not modified with isophthalic acid was used (Comparative Example 3), the strength and pencil hardness were high, but the light transmittance was significantly low, and the haze was also high.

Claims

1. The composition contains 15 to 85 parts by mass of polystyrene resin and 85 to 15 parts by mass of polyamide resin, The composition contains 0.5 to 15 parts by mass of a compatibilizer relative to 100 parts by mass of the polystyrene resin and the polyamide resin in total, the polyamide resin is composed of diamine-derived structural units and dicarboxylic acid-derived structural units, 70 mol % or more of the diamine-derived structural units are derived from xylylenediamine, and 70 mol % or more of the dicarboxylic acid-derived structural units are derived from an α,ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms and isophthalic acid, Among all constitutional units constituting the polyamide resin, 1 to 10 mol % are constitutional units derived from isophthalic acid, The compatibilizer is a resin composition that contains two or more structural units derived from styrene and has a structure that reacts with at least one of an amino group and a carboxyl group.

2. The polyamide resin is composed of diamine-derived structural units and dicarboxylic acid-derived structural units, and 70 mol % or more of the diamine-derived structural units are derived from xylylenediamine, 85 to 95 mol % or more of the dicarboxylic acid-derived structural units are derived from α,ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms, and 15 to 5 mol % is derived from isophthalic acid (however, the total does not exceed 100 mol %).

3. the polyamide resin is composed of diamine-derived structural units and dicarboxylic acid-derived structural units, 70 mol % or more of the diamine-derived structural units being derived from xylylenediamine, 40 to 60 mol % of the dicarboxylic acid-derived structural units being derived from an α,ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms, and 60 to 40 mol % of the dicarboxylic acid-derived structural units being derived from isophthalic acid (however, the total does not exceed 100 mol %); The resin composition according to claim 1 or 2, comprising a polyamide resin composed of a diamine-derived structural unit and a dicarboxylic acid-derived structural unit, in which 70 mol % or more of the diamine-derived structural units are derived from xylylenediamine, and more than 95 mol % of the dicarboxylic acid-derived structural units are derived from an α,ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms.

4. The resin composition according to any one of claims 1 to 3, wherein the α,ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms is adipic acid.

5. The resin composition according to claim 1, wherein the structure capable of reacting with at least one of an amino group and a carboxyl group includes at least one selected from the group consisting of an epoxy group, a maleic anhydride group, and an oxazoline group.

6. A molded article formed from the resin composition according to any one of claims 1 to 5.

7. A film formed from the resin composition according to any one of claims 1 to 5.

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