Resin composition and molded article thereof

Abstract

To provide a resin composition that can produce molded products with an excellent balance of rigidity and toughness. [Solution] A resin composition comprising at least a polyamide (A), a polyrotaxane (B) in which a cyclic molecule is modified by a graft chain having a hydroxyl group at its terminus, and an epoxy resin (C), wherein, with respect to 100 parts by mass of the total of the polyamide (A), the polyrotaxane (B), and the epoxy resin (C), the polyamide (A) is blended in an amount of 70.0 parts by mass or more and 99.9 parts by mass or less, the polyrotaxane (B) in an amount of 0.05 parts by mass or more and 10.0 parts by mass or less, and the epoxy resin (C) in an amount of 0.05 parts by mass or more and 20.0 parts by mass or less.

Description

[Technical Field]

[0001] The present invention relates to a polyamide resin composition that can produce a molded article with an excellent balance of rigidity and toughness, and a molded article made therefrom, comprising a polyamide, a polyrotaxane modified with a cyclic molecule, an epoxy resin, and a silane coupling agent having a functional group that reacts with an amino group. [Background technology]

[0002] Polyamides are suitable as engineering plastics due to their excellent mechanical properties such as rigidity and toughness, as well as their thermal properties. Therefore, they are widely used in various applications, including injection molding, electrical and electronic components, mechanical parts, and automotive parts. Methods for further improving the toughness of polyamide resins include incorporating olefin-based elastomers or core-shell compounds in which a rubbery core layer is covered with a glassy resin shell layer. As a technique for incorporating olefin-based elastomers, for example, a polyamide resin composition (see, for example, Patent Document 1) has been proposed, comprising a continuous phase made of polyamide resin and a particulate dispersed phase in the continuous phase consisting of polyolefin modified with α,β-unsaturated carboxylic acid. As techniques for incorporating core-shell type compounds, for example, a composite rubber-based graft copolymer made by graft polymerizing vinyl monomers onto multilayer polymer particles having a polyalkyl (meth)acrylate core, a first layer made of polyorganosiloxane, and a second layer made of polyalkyl (meth)acrylate, and an impact-resistant thermoplastic resin composition made of a thermoplastic resin (see, for example, Patent Document 2), a polyamide resin made of dicarboxylic acid units containing terephthalic acid units and diamine units containing 1,9-nonanediamine units and / or 2-methyl-1,8-octanediamine units, and a polyamide resin composition made of resin fine particles having a core-shell structure (see, for example, Patent Document 3).

[0003] On the other hand, as a method to improve impact strength and toughness, for example, a resin composition obtained by reacting a polyolefin modified with an unsaturated carboxylic acid anhydride with a polyrotaxane having a functional group has been proposed (see, for example, Patent Document 4). Furthermore, the resin composition described in Patent Document 5 proposes a method to significantly improve the toughness of polyamide by adding polyrotaxane. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 9-31325 [Patent Document 2] Japanese Patent Application Publication No. 5-339462 [Patent Document 3] Japanese Patent Publication No. 2000-186204 [Patent Document 4] Japanese Patent Publication No. 2013-209460 [Patent Document 5] International Publication No. 2016 / 167247 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] When resin compositions are applied to various uses, particularly automotive structural materials, it is necessary to achieve both rigidity and toughness. Resin compositions disclosed in Patent Documents 1 to 3 improve impact resistance and toughness by incorporating olefin-based elastomers and core-shell type compounds, but suffer from a decrease in rigidity. As disclosed in Patent Document 4, it was known that the impact strength and toughness of polyolefins could be improved by using polyrotaxanes, but the polyrotaxanes disclosed therein have low compatibility and reactivity with polyamides, making it difficult to apply such polyrotaxanes to modify polyamides with excellent rigidity. On the other hand, as shown in Patent Document 5, it was possible to obtain polyamides with both rigidity and toughness by adding polyrotaxanes, but there is a challenge in achieving high toughness when the amount of polyrotaxane added is reduced.

[0006] In view of the problems of the above-mentioned background technology, the present invention aims to provide a resin composition that can produce molded articles with an excellent balance of rigidity and toughness even when the amount of polyrotaxane added is reduced. [Means for solving the problem]

[0007] To solve the above problems, the present invention has the following configuration. (1) A resin composition comprising at least a polyamide (A), a polyrotaxane (B) in which a cyclic molecule is modified by a graft chain having a hydroxyl group at its terminus, and an epoxy resin (C), wherein, with respect to 100 parts by mass of the total of the polyamide (A), the polyrotaxane (B), and the epoxy resin (C), the polyamide (A) is comprised in an amount of 70.0 parts by mass or more and 99.9 parts by mass or less, the polyrotaxane (B) in an amount of 0.05 parts by mass or more and 10.0 parts by mass or less, and the epoxy resin (C) in an amount of 0.05 parts by mass or more and 20.0 parts by mass or less. (2) The resin composition according to (1), characterized in that the epoxy equivalent of the epoxy resin (C) is 300 or more and 5000 or less. (3) The resin composition according to (1) or (2), characterized in that the epoxy resin (C) is an epoxy resin containing a skeleton selected from a bisphenol A type skeleton, a bisphenol F type skeleton, and a biphenyl type skeleton in its main chain. (4) A molded article comprising any of the resin compositions described in (1) to (3). [Effects of the Invention]

[0008] The resin composition of the present invention makes it possible to obtain molded articles with an excellent balance of rigidity and toughness at room temperature and low temperature. [Modes for carrying out the invention]

[0009] The present invention will be described in more detail below.

[0010] The resin composition of the present invention comprises a polyamide (A), a polyrotaxane (B) (hereinafter sometimes abbreviated as polyrotaxane (B)) in which a cyclic molecule is modified by graft chains having hydroxyl groups at their ends, and an epoxy resin (C). By incorporating polyamide (A), rigidity and heat resistance can be improved, and by incorporating polyrotaxane (B), toughness can be improved. Furthermore, by incorporating epoxy resin (C), crystallization of the graft chains of polyrotaxane (B) is suppressed, and polyrotaxane (B) is finely dispersed in polyamide (A). In addition, the epoxy resin (C) reacts with the terminal functional groups of polyamide (A) and the hydroxyl groups at the ends of the graft chains that modify the cyclic molecule of polyrotaxane (B), forming a copolymer of polyamide (A) and polyrotaxane (B), thereby improving toughness while maintaining rigidity. Furthermore, the polyrotaxane (B) bonded to the polyamide (A) eliminates stress concentration on the polyamide (A) even under low-temperature conditions, thereby improving toughness. Since the reaction product, in which the ends of the polyamide (A) and the hydroxyl groups at the graft chain ends of the polyrotaxane (B) are bonded via epoxy resin (C), is produced by a complex reaction between polymers, it is not practical to specify its structure. Therefore, this invention is defined by the amount of each component used.

[0011] The polyamide (A) in the resin composition of the present invention mainly consists of amino acid, lactam, or diamine and dicarboxylic acid residues. Representative examples of these raw materials include amino acids such as 6-aminocaproic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, and para-aminomethylbenzoic acid; lactams such as ε-caprolactam and ω-laurolactam; aliphatic diamines such as tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, 2-methylpentamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, 2,2,4- / 2,4,4-trimethylhexamethylenediamine and 5-methylnonamethylenediamine; aromatic diamines such as metaxylylenediamine and paraxylylenediamine; 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, and bi Examples include alicyclic diamines such as s(4-aminocyclohexyl)methane, bis(3-methyl-4-aminocyclohexyl)methane, 2,2-bis(4-aminocyclohexyl)propane, bis(aminopropyl)piperazine, and aminoethylpiperazine; aliphatic dicarboxylic acids such as adipic acid, suberic acid, azelaic acid, sebacic acid, and dodecanedioic acid; aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, 2-chloroterephthalic acid, 2-methylterephthalic acid, 5-methylisophthalic acid, 5-sodium sulfoisophthalic acid, 2,6-naphthalenedicarboxylic acid, hexahydroterephthalic acid, and hexahydroisophthalic acid; and alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, and 1,3-cyclopentanedicarboxylic acid. In the present invention, two or more polyamide homopolymers or copolymers derived from these raw materials may be blended.

[0012] Specific examples of polyamide (A) include polycaproamide (nylon 6), polyhexamethylene adipamide (nylon 66), polytetramethylene adipamide (nylon 46), polytetramethylene sevacamide (nylon 410), polypentamethylene adipamide (nylon 56), polypentamethylene sevacamide (nylon 510), polyhexamethylene sevacamide (nylon 610), polyhexamethylene dodecamide (nylon 612), polydecamethylene adipamide (nylon 106), and polydecamethylene sevacamide (nylon 612). Nylon 1010), Polydecamethylene dodecamide (Nylon 1012), Polyundecaneamide (Nylon 11), Polydodecaneamide (Nylon 12), Polycaproamide / Polyhexamethylene adipamide copolymer (Nylon 6 / 66), Polycaproamide / Polyhexamethylene terephthalamide copolymer (Nylon 6 / 6T), Polyhexamethylene adipamide / Polyhexamethylene terephthalamide copolymer (Nylon 66 / 6T), Polyhexamethylene adipamide / Polyhexamethylene isophthalamide copolymer (Nylon 1010), Polydecamethylene dodecamide (Nylon 1012), Polyundecaneamide (Nylon 11), Polydodecaneamide (Nylon 12), Polycaproamide / Polyhexamethylene adipamide copolymer (Nylon 6 / 66), Polycaproamide / Polyhexamethylene terephthalamide copolymer (Nylon 6 / 6T), Polyhexamethylene adipamide / Polyhexamethylene isophthalamide copolymer (Nylon 6 / 6T) Polyhexamethylene terephthalamide / polyhexamethylene isophthalamide copolymer (Nylon 6T / 6I), polyhexamethylene terephthalamide / polydodecaneamide copolymer (Nylon 6T / 12), polyhexamethylene adipamide / polyhexamethylene terephthalamide / polyhexamethylene isophthalamide copolymer (Nylon 66 / 6T / 6I), polyxylylene adipamide (Nylon XD6), polyxylylene sebaamide (Nylon XD10), polyhexamethylene terephthalamide / poly Examples include pentamethylene terephthalamide copolymer (nylon 6T / 5T), polyhexamethylene terephthalamide / poly-2-methylpentamethylene terephthalamide copolymer (nylon 6T / M5T), polypentamethylene terephthalamide / polydecamethylene terephthalamide copolymer (nylon 5T / 10T), polynonamethylene terephthalamide (nylon 9T), polydecamethylene terephthalamide (nylon 10T), polydodecamethylene terephthalamide (nylon 12T), and copolymers thereof. Two or more of these may be blended. Here, " / " indicates a copolymer, and the same applies hereafter.

[0013] In the resin composition of the present invention, the melting point of polyamide (A) is preferably 150°C or higher and less than 300°C. If the melting point is 150°C or higher, the heat resistance can be improved. On the other hand, if the melting point is less than 300°C, the processing temperature during the manufacture of the resin composition can be appropriately suppressed, and the thermal decomposition of polyrotaxane (B) can be inhibited.

[0014] Here, the melting point of the polyamide in this invention is defined as the temperature of the endothermic peak that appears when the polyamide is cooled from a molten state to 30°C at a rate of 20°C / min under an inert gas atmosphere using a differential scanning calorimeter, and then heated to the melting point + 40°C at a rate of 20°C / min. However, if two or more endothermic peaks are detected, the temperature of the endothermic peak with the greatest peak intensity is taken as the melting point.

[0015] Specific examples of polyamides having a melting point of 150 °C or higher and less than 300 °C include polycaproamide (nylon 6), polyhexamethylene adipamide (nylon 66), polypentamethylene adipamide (nylon 56), polytetramethylene adipamide (nylon 46), polyhexamethylene sebacamide (nylon 610), polyhexamethylene dodecamide (nylon 612), polyundecanamide (nylon 11), polydodecanamide (nylon 12), polycaproamide / polyhexamethylene adipamide copolymer (nylon 6 / 66), polycaproamide / polyhexamethylene terephthalamide copolymer (nylon 6 / 6T), polyhexamethylene adipamide / polyhexamethylene isophthalamide copolymer (nylon 66 / 6I), polyhexamethylene terephthalamide / polyhexamethylene isophthalamide copolymer (nylon 6T / 6I), polyhexamethylene terephthalamide / polydodecanamide copolymer (nylon 6T / 12), polyhexamethylene adipamide / polyhexamethylene terephthalamide / polyhexamethylene isophthalamide copolymer (nylon 66 / 6T / 6I), polyxylylene adipamide (nylon XD6), polyhexamethylene terephthalamide / poly-2-methylpentamethylene terephthalamide copolymer (nylon 6T / M5T), polynonamethylene terephthalamide (nylon 9T), and copolymers thereof. Two or more of these may be blended.

[0016] The resin composition of the present invention is prepared by blending a polyamide (A), a polyrotaxane (B) in which cyclic molecules are modified with graft chains having hydroxyl groups at their terminals, and an epoxy resin (C). The epoxy resin (C) reacts with the amine terminals and carboxyl terminals of the polyamide (A) and the hydroxyl groups at the graft chain terminals of the polyrotaxane (B), respectively, so that the toughness improvement effect of the polyrotaxane can be spread throughout the resin composition.

[0017] The degree of polymerization of the polyamide (A) is not particularly limited, but it is preferably in the range of 1.5 or more and 5.0 or less in terms of relative viscosity measured at 25°C in a 98% sulfuric acid solution with a resin concentration of 0.01 g / ml. If the relative viscosity is 1.5 or more, the toughness, rigidity, abrasion resistance, fatigue resistance, and creep resistance of the obtained molded product can be further improved. More preferably, it is 2.0 or more. On the other hand, if the relative viscosity is 5.0 or less, the fluidity is excellent, and thus the molding processability is excellent.

[0018] The blending amount of the polyamide (A) in the resin composition of the present invention is 70.0 parts by mass or more and 99.9 parts by mass or less with respect to a total of 100 parts by mass of the polyamide (A), the polyrotaxane (B), and the epoxy resin (C). If the blending amount of the polyamide (A) is less than 70.0 parts by mass, the rigidity and heat resistance of the obtained molded product will decrease. The blending amount of the polyamide (A) is preferably 90.0 parts by mass or more, more preferably 95.0 parts by mass or more, and even more preferably 98.0 parts by mass or more. On the other hand, if the blending amount of the polyamide (A) exceeds 99.9 parts by mass, the blending amount of the polyrotaxane (B) will be relatively small, and thus the toughness of the molded product will decrease.

[0019] The resin composition of the present invention is blended with a polyrotaxane (B) in which cyclic molecules are modified by a graft chain having a hydroxyl group at the terminal. A rotaxane is generally a molecule in which a cyclic molecule penetrates a dumbbell-shaped axle molecule (a linear molecule having bulky block groups at both ends. Hereinafter, referred to as "linear molecule"), as described in, for example, Harada, A., Li, J. & Kamachi, M., Nature 356, 325-327. A polyrotaxane refers to a molecule in which a plurality of cyclic molecules penetrate one linear molecule.

[0020] Polyrotaxanes consist of linear molecules and multiple cyclic molecules, with linear molecules penetrating the openings of the multiple cyclic molecules. Furthermore, both ends of the linear molecules have bulky blocking groups to prevent the cyclic molecules from detaching. In polyrotaxanes, cyclic molecules can move freely along the linear molecules, but the blocking groups prevent them from detaching. That is, the linear and cyclic molecules maintain their shape through mechanical bonding, not chemical bonding. Because of the high mobility of the cyclic molecules, such polyrotaxanes have the effect of relieving external stress and internal stress. Moreover, by incorporating polyrotaxanes modified with graft chains having hydroxyl groups at their ends into polyamides, it is possible to extend a similar effect to the polyamide.

[0021] The linear molecule is not particularly limited as long as it has a functional group that penetrates the opening of the cyclic molecule and can react with the blocking group. Preferably used linear molecules include polyalkylene glycols such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol; terminal hydroxyl group polyolefins such as polybutadiene diol, polyisoprendiol, polyisobutylenediol, poly(acrylonitrile-butadiene)diol, hydrogenated polybutadiene diol, polyethylene diol, and polypropylene diol; polyesters such as polycaprolactone diol, polylactic acid, polyethylene adipate, polybutylene adipate, polyethylene terephthalate, and polybutylene terephthalate; terminal functional polysiloxanes such as terminal silanol-type polydimethylsiloxane; terminal amino group chain polymers such as terminal amino group polyethylene glycol, terminal amino group polypropylene glycol, and terminal amino group polybutadiene; and trifunctional or more polyfunctional chain polymers having three or more of the above functional groups in one molecule. Among these, polyethylene glycol and / or terminal amino group polyethylene glycol are preferred due to the ease of synthesis of polyrotaxanes.

[0022] The number-average molecular weight of the linear molecules is preferably 2,000 or more, which can further improve rigidity. More preferably 10,000 or more. On the other hand, it is preferably 100,000 or less, which can improve compatibility with polyamide (A) and refine the phase separation structure, thereby further improving toughness. More preferably 50,000 or less. Here, the number-average molecular weight of the linear molecules refers to the value in terms of polymethyl methacrylate, measured using gel permeation chromatography with hexafluoroisopropanol as the solvent and Shodex® HFIP-806M (2 tubes) + HFIP-LG as the column.

[0023] The aforementioned blocking group is not particularly limited as long as it can bond to the terminal functional group of a linear molecule and is bulky enough to prevent the cyclic molecule from detaching from the linear molecule. Preferred blocking groups include dinitrophenyl group, cyclodextrin group, adamantyl group, trityl group, fluoresceinyl group, pyrenyl group, anthracenyl group, and the main chain or side chain of a polymer with a number average molecular weight of 1,000 to 1,000,000. Two or more of these may be present.

[0024] The cyclic molecule is not particularly limited as long as a linear molecule can pass through its opening. Preferred cyclic molecules include cyclodextrins, crown ethers, cryptondates, macrocyclic amines, calixarenes, and cyclophanes. Cyclodextrins are compounds in which multiple glucose molecules are linked cyclically by α-1,4 bonds. α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin are more preferably used.

[0025] The polyrotaxane (B) in the present invention is characterized in that the cyclic molecule is modified by a graft chain having hydroxyl groups at its terminals. A copolymer of polyamide (A) and polyrotaxane (B) is formed by bonding the terminal functional groups of polyamide (A) and the hydroxyl groups at the terminals of the graft chain of polyrotaxane (B) via epoxy resin (C). As a result, the toughness can be improved while maintaining the rigidity of polyamide (A), and a good balance between rigidity and toughness can be achieved.

[0026] The graft chain is preferably composed of polyester. Aliphatic polyester is more preferred in terms of compatibility with polyamide (A) and solubility in organic solvents. Examples of aliphatic polyesters include polylactic acid, polyglycolic acid, poly3-hydroxybutyrate, poly4-hydroxybutyrate, poly(3-hydroxybutyrate / 3-hydroxyvalerate), and poly(ε-caprolactone). Among these, poly(ε-caprolactone) is more preferred in terms of compatibility with polyamide (A). A polyrotaxane (B) in which a cyclic molecule is modified by a graft chain having a hydroxyl group at its terminus can be obtained by the following method. For example, a polyrotaxane in which the terminus of the graft chain is modified with a hydroxyl group can be obtained by grafting poly(ε-caprolactone) onto cyclodextrins.

[0027] The hydroxyl group concentration at the end of the graft chain of polyrotaxane (B) is 2 × 10⁻¹⁰ -5 mol / g or more 3×10 -3 Preferably, the hydroxyl group concentration should be 2 × 10⁻⁶. -5 By increasing the concentration to mol / g or higher, the reactivity with epoxy resin (C) can be improved. As a result, the toughness of polyamide (A) can be further improved while maintaining its rigidity, allowing for a better balance between rigidity and toughness. 5×10 -5 More preferably mol / g or higher, 1 × 10 -4 A concentration of mol / g or higher is even more preferable. On the other hand, the hydroxyl group concentration is 3 × 10⁻⁶. -3By keeping the concentration below mol / g, aggregation due to association between hydroxyl groups of polyrotaxane (B) and excessive chemical crosslinking with polyamide (A) can be suppressed, thereby inhibiting the formation of aggregates and gels and further improving toughness. 2 × 10 -3 A concentration of mol / g or less is more preferable.

[0028] Here, the hydroxyl group concentration at the graft chain ends of polyrotaxane (B) can be determined by titration. A completely dry sample is prepared by drying polyrotaxane (B) for more than 10 hours using an 80°C vacuum dryer. 1.0 g of the completely dry sample is dissolved in 50 ml of toluene, to which a large excess of succinic anhydride is added, and the mixture is heated at 90°C for 6 hours under a nitrogen flow. After concentrating the polymer solution to approximately 50% using an epotherm, the polymer solution is added to a large excess of methanol solution, and the precipitate is collected. The obtained precipitate is dried in a vacuum dryer at 80°C for 8 hours to obtain the polymer. The hydroxyl group concentration can be determined by titrating a solution of 0.2 g of the obtained polymer dissolved in 25 ml of benzyl alcohol with an ethanol solution of 0.02 mol / L potassium hydroxide.

[0029] In the resin composition of the present invention, the weight-average molecular weight of polyrotaxane (B) is preferably 100,000 or more, which can further improve rigidity and toughness. On the other hand, a weight-average molecular weight of 1,000,000 or less is preferable, which improves compatibility with polyamide (A) and further improves toughness. Here, the weight-average molecular weight of polyrotaxane (B) refers to the value converted to polymethyl methacrylate, measured using gel permeation chromatography with hexafluoroisopropanol as the solvent and Shodex® HFIP-806M (2 tubes) + HFIP-LG as the column.

[0030] The amount of polyrotaxane (B) in the resin composition of the present invention is 0.05 parts by mass or more and 10.0 parts by mass or less per 100 parts by mass of the total of polyamide (A), polyrotaxane (B), and epoxy resin (C). If the amount of polyrotaxane (B) is less than 0.05 parts by mass, the amount of polyrotaxane (B) is small, and the stress relaxation effect of the polyrotaxane cannot be transmitted to the entire polyamide (A), resulting in a decrease in toughness. On the other hand, if the amount of polyrotaxane (B) exceeds 10.0 parts by mass, the amount of polyamide (A) becomes relatively small, resulting in a decrease in the rigidity of the molded article. The amount of polyrotaxane (B) is preferably 5.0 parts by mass or less, more preferably 3.0 parts by mass or less, and even more preferably 1.0 part by mass or less.

[0031] The resin composition in the present invention is formulated with epoxy resin (C).

[0032] Examples of epoxy resins (C) include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD ​​type epoxy resin, halogenated bisphenol A type epoxy resin, bisphenol S type epoxy resin, resorcinol type epoxy resin, hydrogenated bisphenol A type epoxy resin, aliphatic epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, naphthalene type epoxy resin, biphenyl type epoxy resin, biphenyl aralkyl type epoxy resin, and dicyclopentadiene type epoxy resin. By incorporating epoxy resin, the crystallization of polyrotaxane is suppressed, and polyrotaxane (B) can be efficiently dispersed in polyamide (A). As a result, the stress-relaxing effect of polyrotaxane can be exerted throughout the resin, and a resin with an excellent balance of rigidity and toughness can be obtained. Among these epoxy resins, it is preferable to use one selected from bisphenol A type epoxy resin, bisphenol F type epoxy resin, and biphenyl type epoxy resin, which have an excellent balance of viscosity and heat resistance and excellent affinity with polyrotaxane (B).

[0033] The epoxy equivalent of the epoxy resin (C) is preferably 300 or more and 5000 or less. An epoxy equivalent of 300 or more suppresses gelation by epoxy groups. More preferably 500 or more, and even more preferably 1000 or more. Furthermore, an epoxy equivalent of 5000 or less provides excellent affinity with polyrotaxane (B) and allows for highly efficient bonding of polyamide (A) and polyrotaxane (B). More preferably 3000 or less, and even more preferably 2500 or less.

[0034] The amount of epoxy resin (C) in the resin composition of the present invention is 0.05 parts by mass or more and 20.0 parts by mass or less, based on 100 parts by mass of the total of polyamide (A), polyrotaxane (B), and epoxy resin (C). If the amount of epoxy resin (C) is less than 0.05 parts by mass, the amount of epoxy resin will be less than that of polyrotaxane (B), so the polyrotaxane (B) cannot be efficiently dispersed in the polyamide (A), and the toughness will not improve. On the other hand, if the amount of epoxy resin (C) exceeds 20.0 parts by mass, excessively crosslinked reactants will be generated by the reaction with polyamide (A) and polyrotaxane (B), resulting in a decrease in toughness. The amount of epoxy resin is preferably 10.0 parts by mass or less, more preferably 5.0 parts by mass or less, and even more preferably 1.0 part by mass or less. Furthermore, it is desirable that the amount of epoxy resin (C) is 1 to 5 times the amount of polyrotaxane (B). If the amount of epoxy resin (C) to polyrotaxane (B) is less than 1, the amount of epoxy resin is low compared to polyrotaxane (B), making it impossible to efficiently disperse the polyrotaxane (B) in the polyamide (A), and thus the toughness does not improve. It is more preferable that the amount of epoxy resin (C) to polyrotaxane (B) is 1.5 times or more. On the other hand, if the amount of epoxy resin (C) to polyrotaxane (B) is 5 times or more, excessively crosslinked reactants are formed by the reaction with polyamide (A) and polyrotaxane (B), resulting in a decrease in toughness. It is more preferable that the amount of epoxy resin (C) to polyrotaxane (B) is 3 times or less.

[0035] The resin composition of the present invention may further contain fillers, thermoplastic resins other than polyamide, various additives, etc., to the extent that the objectives of the present invention are not impaired.

[0036] By incorporating fillers, the strength and rigidity of the resulting molded product can be further improved. The fillers may be organic or inorganic, and may be fibrous or non-fibrous. Two or more of these may be combined.

[0037] Examples of fibrous fillers include glass fibers and carbon fibers. These may be coated or bundled with thermoplastic resins such as ethylene / vinyl acetate or thermosetting resins such as epoxy resins. Examples of cross-sectional shapes of the fibrous fillers include circular, flattened, cocoon-shaped, oval, elliptical, and rectangular shapes.

[0038] Examples of non-fibrous fillers include non-swelling silicates such as talc, warlastenite, zeolite, sericite, mica, kaolin, clay, pyrophyllite, bentonite, asbestos, alumina silicate, and calcium silicate; swelling layered silicates such as Li-type fluoroteniolite, Na-type fluoroteniolite, Na-type tetrasilicon fluorimica, and Li-type tetrasilicon fluorimica swelling mica; metal oxides such as silicon oxide, magnesium oxide, alumina, silica, diatomaceous earth, zirconium oxide, titanium oxide, iron oxide, zinc oxide, calcium oxide, tin oxide, and antimony oxide; calcium carbonate, magnesium carbonate, zinc carbonate, barium carbonate, and Examples include metal carbonates such as romite and hydrotalcite, metal sulfates such as calcium sulfate and barium sulfate, metal hydroxides such as magnesium hydroxide, calcium hydroxide, aluminum hydroxide, and basic magnesium carbonate, smectite-type clay minerals such as montmorillonite, bydelite, nontronite, saponite, hectorite, and souconite, and various clay minerals such as vermiculite, halloysite, kanemite, kenyaite, zirconium phosphate, and titanium phosphate, as well as glass beads, glass flakes, ceramic beads, boron nitride, aluminum nitride, silicon carbide, calcium phosphate, carbon black, and graphite. In the above-mentioned swollen layered silicates, the exchangeable cations present between the layers may be exchanged with organo-onium ions. Examples of organo-onium ions include ammonium ions, phosphonium ions, and sulfonium ions.

[0039] Specific examples of resins other than polyamides include polyester resins, polyolefin resins, modified polyphenylene ether resins, polysulfone resins, polyketone resins, polyetherimide resins, polyarylate resins, polyethersulfone resins, polyetherketone resins, polythioetherketone resins, polyetheretherketone resins, polyimide resins, polyamideimide resins, and tetrafluoroethylene resins. Two or more of these may be blended together.

[0040] Specific examples of various additives include heat stabilizers, coupling agents such as organosilane compounds, organotitanate compounds, and organoborane compounds, plasticizers such as polyalkylene oxide oligomer compounds, thioether compounds, ester compounds, and organophosphorus compounds, nucleating agents such as organophosphorus compounds and polyetheretherketones, metal soaps such as montanic acid waxes, lithium stearate, and aluminum stearate, mold release agents such as ethylenediamine-stearic acid-sebacic acid polycondensate and silicone compounds, color inhibitors such as hypophosphates, lubricants, UV inhibitors, colorants, flame retardants, and foaming agents. When these additives are incorporated, the amount is preferably 10 parts by mass or less, and more preferably 1 part by mass or less, per 100 parts by mass of polyamide (A), in order to fully utilize the characteristics of polyamide.

[0041] Copper compounds are commonly used as heat stabilizers. Examples of copper compounds include cuprous chloride, cupric chloride, cuprous bromide, cupric bromide, cuprous iodide, cupric iodide, cupric sulfate, cupric nitrate, copper phosphate, cuprous acetate, cupric acetate, cupric salicylate, cupric stearate, and cupric benzoate, and those that are industrially available are preferred. Other heat stabilizers besides copper compounds include phenolic compounds such as N,N'-hexamethylenebis(3,5-di-t-butyl-4-hydroxyhydrocinnamide) and tetrakis[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, phosphorus compounds, sulfur compounds such as mercaptobenzimidazole compounds, dithiocarbamate compounds, and organic thioacid compounds, and amine compounds such as N,N'-di-2-naphthyl-p-phenylenediamine and 4,4'-bis(α,α-dimethylbenzyl)diphenylamine. Two or more of these may be combined.

[0042] There are no particular limitations on the method for producing the polyamide resin composition of the present invention, but examples include kneading in a molten state or mixing in a solution state. From the viewpoint of improving reactivity, kneading in a molten state is preferred. Examples of molten kneading apparatus include single-screw extruders, twin-screw extruders, quadruple-screw extruders, and other multi-screw extruders, as well as twin-screw single-screw composite extruders and kneaders. From the viewpoint of productivity, an extruder capable of continuous production is preferred, and from the viewpoint of improved kneadability, reactivity, and productivity, a twin-screw extruder is more preferred.

[0043] The following explanation will describe the production of the resin composition of the present invention using a twin-screw extruder as an example. From the viewpoint of suppressing thermal degradation of polyrotaxane (B) and further improving toughness, the maximum resin temperature is preferably 300°C or lower. On the other hand, the maximum resin temperature is preferably above the melting point of polyamide (A). Here, the maximum resin temperature refers to the highest temperature measured by resin thermometers evenly installed at multiple locations in the extruder.

[0044] Furthermore, from the viewpoint of further suppressing the thermal degradation of polyamide (A) and polyrotaxane (B), the extrusion rate of the resin composition is preferably 0.01 kg / h or more, and more preferably 0.05 kg / h or more, per rpm of screw rotation. On the other hand, from the viewpoint of further promoting the reaction between the polyamide (A) and polyrotaxane (B) resin and more easily forming the aforementioned sea-island structure, it is preferable to have an extrusion rate of 1 kg / h or less per rpm of screw rotation. Here, the extrusion rate refers to the mass (kg) of the resin composition discharged from the extruder per hour.

[0045] In this way, the resin composition can be molded by commonly known methods to obtain various molded articles such as sheets and films. Examples of molding methods include injection molding, injection compression molding, extrusion molding, compression molding, blow molding, and press molding.

[0046] The resin composition and molded articles of the present invention, taking advantage of their excellent properties, can be used in a variety of applications, including automotive parts, gas tank liners, electrical and electronic components, building materials, various containers, daily necessities, household goods, and hygiene products. In particular, they are especially preferred for automotive exterior parts requiring toughness and rigidity, as well as automotive electrical components, automotive under-hood parts, automotive gear parts, housings, connectors, reflectors, and other electrical and electronic component applications.Specifically, this includes automotive engine peripheral parts such as engine covers, air intake pipes, timing belt covers, intake manifolds, filler caps, throttle bodies, and cooling fans; automotive under-hood parts such as cooling fans, radiator tank tops and bases, cylinder head covers, oil pans, brake lines, fuel line tubes, high-pressure gas tank liners, and exhaust gas system parts; automotive gear parts such as gears, actuators, bearing retainers, bearing cages, chain guides, and chain tensioners; automotive interior parts such as shift lever brackets, steering lock brackets, key cylinders, door inner handles, door handle cowls, interior mirror brackets, air conditioning switches, instrument panels, console boxes, glove boxes, steering wheels, and trim; and front fenders, rear fenders, fuel lids, door panels, cylinder head covers, door mirror stays, tailgate panels, license plate garnishes, and roof racks. Suitable examples of automotive exterior parts include engine mount brackets, rear garnishes, rear spoilers, trunk lids, rocker moldings, moldings, lamp housings, front grilles, mudguards, and side bumpers; intake and exhaust system parts include air intake manifolds, intercooler inlets, exhaust pipe covers, inner bushings, bearing retainers, engine mounts, engine head covers, resonators, and throttle bodies; engine coolant system parts include chain covers, thermostat housings, outlet pipes, radiator tanks, oil inertors, and delivery pipes; automotive electrical components include connectors and wire harness connectors, motor parts, lamp sockets, sensor switches, and combination switches; and electrical and electronic components such as SMT-compatible connectors, sockets, card connectors, jacks, power supply components, switches, sensors, capacitor base plates, relays, resistors, fuse holders, coil bobbins, IC and LED compatible housings, and reflectors. [Examples]

[0047] Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples. The following raw materials were used to obtain the resin composition of each example.

[0048] <Polyamide> (A): Nylon 6 resin ("Amilan" (registered trademark) manufactured by Toray Industries, Inc.), relative viscosity η r = 2.70, melting point 225 °C. Here, the above relative viscosity η r was measured at 25 °C in a 0.01 g / ml solution of 98% concentrated sulfuric acid. The melting point was determined as the temperature of the endothermic peak that appears when the polyamide was cooled from the molten state to 30 °C at a cooling rate of 20 °C / min in an inert gas atmosphere using a differential scanning calorimeter, and then heated to the melting point + 40 °C at a heating rate of 20 °C / min.

[0049] <Polyrotaxane> (B): Polyrotaxane ("Celm" (registered trademark) Super Polymer SH1300P manufactured by Advanced Soft Materials Co., Ltd.), the number average molecular weight of the linear polyethylene glycol is 10,000, and the overall weight average molecular weight is 180,000. The graft chain end is a hydroxyl group, and the hydroxyl group concentration determined by the following method is 1.55 × 10 -3 mol / g.

[0050] An absolutely dry sample of polyrotaxane dried for 10 hours or more using an 80 °C vacuum dryer was prepared. An excess of succinic anhydride was added to a solution of 1.0 g of the absolutely dry sample dissolved in 50 ml of toluene, and heated at 90 °C for 6 hours under a nitrogen flow. After concentrating with an evaporator until the polymer concentration reached about 50%, the polymer solution was added to a large excess of methanol solution, and the precipitate was collected. The obtained precipitate was dried in a vacuum dryer at 80 °C for 8 hours to obtain a polymer. For a solution of 0.2 g of the obtained polymer dissolved in 25 ml of benzyl alcohol, titration was performed using an ethanol solution of potassium hydroxide with a concentration of 0.02 mol / L, and the hydroxyl group concentration was calculated.

[0051] "Celm®" superpolymer is a polyrotaxane in which the cyclic molecule is modified by a graft chain of poly(ε-caprolactone) α-cyclodextrin, the linear molecule is polyethylene glycol, and the blocking group is an adamantane group.

[0052] Here, the weight-average molecular weight of the polyrotaxane is measured using gel permeation chromatography with hexafluoroisopropanol as the solvent and Shodex® HFIP-806M (2 tubes) + HFIP-LG as the column, and is expressed as a value converted to polymethyl methacrylate.

[0053] <Epoxy resin> (C-1): Bisphenol A type epoxy resin jER(registered trademark) 1007FS manufactured by Mitsubishi Chemical Corporation, with an epoxy equivalent of 1,300 g / eq. (C-2): Bisphenol A type epoxy resin jER(registered trademark) 1004FS manufactured by Mitsubishi Chemical Corporation, with an epoxy equivalent of 810 g / eq. (C-3): Bisphenol A type epoxy resin jER(registered trademark) 1009F manufactured by Mitsubishi Chemical Corporation, with an epoxy equivalent of 2,000 g / eq. <Phenoxy resin> (C) Epoxy resin-like resin not falling under this category: Bisphenol A type phenoxy resin jER(registered trademark) 1256 manufactured by Mitsubishi Chemical Corporation, with a number average molecular weight of 45,000 g / mol.

[0054] <Evaluation Method> The evaluation methods for each example and comparative example are described below. Unless otherwise specified, the evaluation sample size was n=5, and the average value was calculated.

[0055] (1) Toughness (tensile elongation at fracture) The pellets obtained in each example and comparative example were dried under reduced pressure at 80°C for 12 hours, and then injection molded using an injection molding machine (SG75H-MIV, Sumitomo Heavy Industries, Ltd.) under the conditions of cylinder temperature: 240°C and mold temperature: 80°C to produce a 1A type multipurpose test specimen in accordance with ISO 527-1:2012. Tensile tests were performed on the tensile test specimens obtained from these multipurpose test specimens using a precision universal testing machine AG-20kNX (Shimadzu Corporation) at room temperature with a tensile speed of 50 mm / min, in accordance with ISO 527-1:2012, and the tensile elongation at fracture was measured.

[0056] (2) Stiffness (flexural modulus) The pellets obtained in each example and comparative example were dried under reduced pressure at 80°C for 12 hours, and multipurpose test specimens conforming to ISO 178 were prepared by injection molding using an injection molding machine (Sumitomo Heavy Industries SG75H-MIV) under the conditions of cylinder temperature: 240°C and mold temperature: 80°C. The bending test specimens obtained from these multipurpose test specimens were subjected to bending tests in accordance with ISO 178 using a precision universal testing machine AG-20kNX (Shimadzu Corporation) at room temperature with a crosshead speed of 2 mm / min, and the bending modulus of elasticity was determined.

[0057] (3) Low-temperature properties (toughness (tensile elongation at fracture) at -40°C) The pellets obtained in each example and comparative example were dried under reduced pressure at 80°C for 12 hours, and then injection molded using an injection molding machine (Sumitomo Heavy Industries SG75H-MIV) under the conditions of cylinder temperature: 240°C and mold temperature: 80°C to produce Type 1A multipurpose test specimens in accordance with ISO 527-1:2012. The obtained test specimens were subjected to soaking treatment in a constant temperature bath at -40°C for 0.5 hours or more. After soaking treatment, the test specimens were subjected to tensile testing in accordance with ISO 527-1:2012 using a precision universal testing machine AG-50kNX (Shimadzu Corporation) at -40°C at a tensile speed of 50 mm / min, and the tensile elongation at fracture was measured.

[0058] (Examples 1-8, Comparative Examples 1-5) Polyamide resin, polyrotaxane, and epoxy resin were pre-blended to the compositions shown in Tables 1 and 2, and supplied to a twin-screw extruder (TEX30α, manufactured by Japan Steel Works) set to a cylinder temperature of 240°C and a screw rotation speed of 200 rpm for melt-kneading. After melt-kneading, the extruded gut was pelletized to obtain pellets. The results of evaluation using the obtained pellets by the above method are shown in Tables 1 and 2.

[0059] [Table 1]

[0060] [Table 2]

[0061] A comparison of Examples 1-8 and Comparative Examples 1-5 shows that by blending specific amounts of polyrotaxane, in which the graft chain ends are modified with hydroxyl groups, and epoxy resin with polyamide, a coupling reaction occurs between the polyamide and polyrotaxane due to the epoxy groups. This results in superior toughness while maintaining rigidity compared to cases where phenoxy resin, which has a similar structure to epoxy resin, is blended.

Claims

1. A resin composition comprising at least a polyamide (A), a polyrotaxane (B) in which a cyclic molecule is modified by a graft chain having a hydroxyl group at its terminus, and an epoxy resin (C), wherein, with respect to 100 parts by mass of the total of the polyamide (A), the polyrotaxane (B), and the epoxy resin (C), the polyamide (A) is blended in an amount of 70.0 parts by mass or more and 99.9 parts by mass or less, the polyrotaxane (B) in an amount of 0.05 parts by mass or more and 10.0 parts by mass or less, and the epoxy resin (C) in an amount of 0.05 parts by mass or more and 20.0 parts by mass or less.

2. The resin composition according to claim 1, characterized in that the epoxy equivalent of the epoxy resin (C) is 300 or more and 5000 or less.

3. The resin composition according to claim 1, characterized in that the epoxy resin (C) is an epoxy resin containing a skeleton selected from a bisphenol A type skeleton, a bisphenol F type skeleton, and a biphenyl type skeleton in its main chain.

4. A molded article comprising the resin composition described in any one of claims 1 to 3.

Images