JP7626612B2 - Polyamide composition and molded article - Google Patents

Description

The present invention relates to a polyamide composition and a molded article.

In recent years, as problems such as global warming and marine plastics have become more serious and there are concerns about the depletion of petroleum resources, the use of biomass plastics has attracted attention from the perspective of protecting the global environment. Examples of biomass plastics that have been developed include polylactic acid, polybutylene succinate, and more recently biopolyethylene. However, these biomass plastics have poor heat resistance, with melting points below 180°C, so their use is currently restricted. An effective method of improving the heat resistance of plastics is to introduce aromatic rings into the molecular chain, but there are only a limited number of monomers that have aromatic rings among biomass-derived raw materials. Among these, 2,5-furandicarboxylic acid is an aromatic monomer that is obtained from biomass, and polyamides made from this are expected to have higher heat resistance than the biomass plastics mentioned above.

As examples of polyamides using 2,5-furandicarboxylic acid, for example, Patent Documents 1 to 3 disclose polyamides using 2,5-furandicarboxylic acid and aromatic diamines, aliphatic diamines, or alicyclic diamines. Patent Documents 1 to 3 also disclose polyamides using two or more dicarboxylic acids with 2,5-furandicarboxylic acid as the main component and two or more diamines with xylylenediamine as the main component.

JP 2013-006963 A JP 2017-101180 A Special table 2018-537573 publication

However, the polyamides described in Patent Documents 1 to 3 have low crystallinity and do not have sufficient mechanical properties when molded, limiting their applications.

The present invention has been made in consideration of the above circumstances, and provides a polyamide composition that has crystallinity and excellent mechanical properties when molded into a molded article, and a molded article using the polyamide composition.

That is, the present invention includes the following aspects.
(1) A polyamide composition comprising a block copolymer having a polyamide block (A1) having a furan ring and a polyamide block (A2) not having a furan ring.
(2) The polyamide composition according to (1), wherein the polyamide block (A1) has a 2,5-furandicarboxylic acid unit and one or more diamine units selected from the group consisting of an aromatic diamine unit, an alicyclic diamine unit, and an aliphatic diamine unit.
(3) The polyamide composition according to (1) or (2), wherein the polyamide block (A1) has a 2,5-furandicarboxylic acid unit and an aromatic diamine unit.
(4) The polyamide composition according to any one of (1) to (3), wherein the polyamide block (A2) has one or more dicarboxylic acid units selected from the group consisting of aliphatic dicarboxylic acid units and aromatic dicarboxylic acid units, and an aliphatic diamine unit.
(5) The polyamide composition according to any one of (1) to (3), wherein the polyamide block (A2) has an aliphatic dicarboxylic acid unit and one or more diamine units selected from the group consisting of an aliphatic diamine unit and an aromatic diamine unit.
(6) The polyamide composition according to any one of (1) to (5), wherein the polyamide constituting the polyamide block (A1) has a number average molecular weight of 300 or more and 6,000 or less.
(7) The polyamide composition according to any one of (1) to (6), wherein the polyamide constituting the polyamide block (A2) has a number average molecular weight of 500 or more and 5,000 or less.
(8) The polyamide composition according to any one of (1) to (7), wherein the polyamide composition has a number average molecular weight of 5,000 or more and 2,0000 or less.
(9) The polyamide composition according to any one of (1) to (8), wherein the polyamide composition has a glass transition temperature Tg of 90° C. or higher and 200° C. or lower.
(10) The polyamide composition according to any one of (1) to (9), wherein the polyamide composition has a melting point Tm of 200° C. or higher and 350° C. or lower.
(11) A molded article obtained by molding the polyamide composition according to any one of (1) to (10).

The polyamide composition of the above aspect can provide a polyamide composition that has crystallinity and has excellent mechanical properties when molded into a molded article. The molded article of the above aspect is made by molding the polyamide composition and has excellent mechanical properties.

Hereinafter, an embodiment of the present invention (hereinafter simply referred to as "the present embodiment") will be described in detail.
The following embodiment is an example for explaining the present invention, and is not intended to limit the present invention to the following content. The present invention can be carried out with appropriate modifications within the scope of the gist thereof.

In this specification, "polyamide" refers to a polymer that has amide (-NHCO-) groups in the main chain.

<Polyamide composition>
The polyamide composition of the present embodiment contains a block copolymer having a polyamide block (A1) having a furan ring (hereinafter may be simply referred to as "polyamide block (A1)") and a polyamide block (A2) not having a furan ring (hereinafter may be simply referred to as "polyamide block (A2)").

Conventional polyamide compositions containing as a main component a random copolymer obtained by copolymerizing a monomer having a furan ring and a monomer not having a furan ring have a problem in that the molecular chains of the random copolymer have an irregular structure, making it difficult to exhibit the expected crystallinity.
In contrast, the polyamide composition of the present embodiment contains, as a main component, a block copolymer obtained by block copolymerizing a polyamide prepolymer having a furan ring and a polyamide prepolymer not having a furan ring, and therefore the molecular chains in the block copolymer can have a regular structure, thereby expressing crystallinity and making it possible to provide various good mechanical properties when molded into an article.
In this specification, "containing a block copolymer as a main component" means that the polyamide composition of the present embodiment contains a block copolymer in an amount sufficient to exert the effects of the polyamide composition. Specifically, the content of the block copolymer is 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more, based on the total mass of the polyamide composition.

<Block copolymer>
The block copolymer has a polyamide block (A1) having a furan ring and a polyamide block (A2) not having a furan ring. The block copolymer may be either linear or branched with two or more branches. The block copolymer may have at least one polyamide block (A1) and at least one polyamide block (A2) in the molecule, and the structure and content ratio thereof are not particularly limited.

When the block copolymer has two or more polyamide blocks (A1) and two or more polyamide blocks (A2), the blocks may be the same or different. In this specification, "different polyamide blocks (A1)" and "different polyamide blocks (A2)" mean that the blocks are different in at least one selected from the group consisting of the monomer units constituting each block, the number average molecular weight, the stereoregularity, and, when multiple monomer units are present, the content ratio of each monomer unit and the form of copolymerization (random, gradient, or block).

[Polyamide block (A1)]
The polyamide block (A1) is a polyamide block having a furan ring in at least one of the structural units of the dicarboxylic acid unit and the diamine unit. The polyamide block (A1) has a furan ring in the molecular chain, which inhibits rotation of the molecular chain, thereby increasing the glass transition temperature Tg of the resulting polyamide composition and improving the mechanical strength.

(Dicarboxylic acid unit)
The dicarboxylic acid unit constituting the polyamide block (A1) may be a dicarboxylic acid unit having a furan ring or a dicarboxylic acid unit not having a furan ring. The polyamide block (A1) may have both a dicarboxylic acid unit having a furan ring and a dicarboxylic acid unit not having a furan ring.
When the dicarboxylic acid unit constituting the polyamide block (A1) is a dicarboxylic acid unit having no furan ring, the diamine unit constituting the polyamide block (A1) is a diamine unit having a furan ring.

Examples of dicarboxylic acids having a furan ring include 2,5-furandicarboxylic acid, 2,4-furandicarboxylic acid, 2,3-furandicarboxylic acid, 3,4-furandicarboxylic acid, etc. Among these, 2,5-furandicarboxylic acid is preferred because of its easy availability.
The dicarboxylic acid having a furan ring may be synthesized from a biological material (biomass material).
These dicarboxylic acids having a furan ring may be used alone or in combination of two or more.

Dicarboxylic acids that do not have a furan ring include aromatic dicarboxylic acids, alicyclic dicarboxylic acids, and aliphatic dicarboxylic acids. Note that the aromatic dicarboxylic acids referred to here do not include dicarboxylic acids that have a furan ring, but are dicarboxylic acids that have an aromatic hydrocarbon group as the molecular skeleton.

Examples of aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, 4,4'-biphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, diphenylether-4,4'-dicarboxylic acid, diphenoxyethane-4,4'-dicarboxylic acid, diphenoxybutane-4,4'-dicarboxylic acid, diphenylethane-4,4'-dicarboxylic acid, diphenylether-3,3'-dicarboxylic acid, diphenoxyether-3,3'-dicarboxylic acid, and diphenylethane-3,3'-dicarboxylic acid. Among these, terephthalic acid and isophthalic acid are preferred from the viewpoint of versatility.

Examples of alicyclic dicarboxylic acids include 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, and 2,5-norbornenedicarboxylic acid.

Examples of aliphatic dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, hydrogenated dimer acid, fumaric acid, maleic acid, itaconic acid, citraconic acid, and dimer acid.

The above-mentioned dicarboxylic acids not having a furan ring may be used alone or in combination of two or more.

(Diamine Unit)
The diamine unit constituting the polyamide block (A1) may be a diamine unit having a furan ring or a diamine unit not having a furan ring. The polyamide block (A1) may have both a diamine unit having a furan ring and a diamine unit not having a furan ring.
When the diamine unit constituting the polyamide block (A1) is a diamine unit having no furan ring, the dicarboxylic acid unit constituting the polyamide block (A1) is a dicarboxylic acid unit having a furan ring.

An example of the diamine having a furan ring is 2,5-bis(aminomethyl) furan .
The diamine having a furan ring may be synthesized from a biological material.
These diamines having a furan ring may be used alone or in combination of two or more.

Diamines that do not have a furan ring include aromatic diamines, alicyclic diamines, and aliphatic diamines. Note that the aromatic diamines referred to here do not include diamines that have a furan ring, but are diamines that have an aromatic hydrocarbon group as the molecular skeleton.

Examples of aromatic diamines include paraxylylenediamine, orthoxylylenediamine, metaxylylenediamine, paradiaminobenzene, metadiaminobenzene, orthodiaminobenzene, etc. Among these, paraxylylenediamine and metaxylylenediamine are preferred.

Examples of alicyclic diamines include 1,4-cyclohexanediamine, 1,3-cyclohexanediamine, 1,2-cyclohexanediamine, isophoronediamine, 4,4'-methylenebis(cyclohexylamine), and 4,4'-methylenebis(2-methylcyclohexylamine).

Examples of aliphatic diamines include 1,5-pentanediamine, 2-methyl-1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 2-methyl-1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, and 1,12-dodecanediamine.

The above-mentioned diamines not having a furan ring may be used alone or in combination of two or more.

As diamines that do not have a furan ring, aliphatic diamines having 5 to 12 carbon atoms or alicyclic diamines having 6 or more carbon atoms are preferred because they can improve heat resistance and moldability. Also, linear aliphatic diamines having 5, 8, 9, or 10 carbon atoms are more preferred because they can increase the proportion of biologically derived raw materials.

Linear aliphatic diamines having 5, 8, 9, or 10 carbon atoms can be obtained by synthesizing carboxylic acids or amino acids having a linear aliphatic hydrocarbon group corresponding to the desired diamine from plant-derived raw materials by biofermentation, ozonolysis, or the like, and then aminating the resulting product. For example, 1,5-pentanediamine can be obtained by aminating L-lysine obtained by fermenting blackstrap molasses. Alternatively, for example, 1,8-octanediamine or 1,9-nonanediamine can be obtained by aminating oleic acid obtained from olive oil or rice bran oil. Alternatively, for example, 1,10-decanediamine can be obtained by aminating ricinoleic acid obtained from castor oil.

Preferred polyamide blocks (A1) include, for example, polyamide blocks having 2,5-furandicarboxylic acid units and one or more diamine units selected from the group consisting of aromatic diamine units, alicyclic diamine units, and aliphatic diamine units; polyamide blocks having 2,5-furandicarboxylic acid units and diamine units having a furan ring, and the like.

More preferred examples of the polyamide block (A1) include a polyamide block having 2,5-furandicarboxylic acid units and aromatic diamine units; and a polyamide block having 2,5-furandicarboxylic acid units and 2,5-bis(aminomethyl)furan units .

More preferred examples of the polyamide block (A1) include a polyamide block having 2,5-furandicarboxylic acid units and paraxylylenediamine units; a polyamide block having 2,5-furandicarboxylic acid units and metaxylylenediamine units, etc.

The above-mentioned polyamide block (A1) is merely one example of a preferred polyamide block (A1), and the preferred polyamide block (A1) is not limited to the above-mentioned one.

(Physical Properties of Polyamide Constituting Polyamide Block (A1))
The number average molecular weight of the polyamide constituting the polyamide block (A1) is preferably 300 to 6,000, more preferably 350 to 5,500, even more preferably 370 to 5,300, and particularly preferably 400 to 5,100. When the number average molecular weight of the polyamide constituting the polyamide block (A1) is within the above numerical range, the heat resistance and mechanical strength of the obtained molded article can be improved. In addition, the viscosity does not become too high, and the moldability is also excellent.

The weight average molecular weight of the polyamide constituting the polyamide block (A1) is preferably 500 or more and 10,000 or less, more preferably 600 or more and 9,000 or less, even more preferably 700 or more and 8,000 or less, and particularly preferably 800 or more and 7,000 or less. When the weight average molecular weight of the polyamide constituting the polyamide block (A1) is within the above numerical range, the heat resistance and mechanical strength of the obtained molded article can be improved. In addition, the viscosity does not become too high, and the moldability is also excellent.

The molecular weight distribution Mw/Mn of the polyamide constituting the polyamide block (A1) is not particularly limited, but is preferably 2.0 to 6.0, more preferably 2.5 to 5.5, and even more preferably 3.0 to 5.0. When the molecular weight distribution of the polyamide constituting the polyamide block (A1) is within the above numerical range, the heat resistance and mechanical strength of the obtained molded article can be improved. In addition, the viscosity does not become too high, and the moldability is also excellent.

The number average molecular weight and weight average molecular weight of the polyamide constituting the polyamide block (A1) are molecular weights calculated in terms of polymethyl methacrylate in molecular weight measurements by gel permeation chromatography (GPC). The molecular weight distribution Mw/Mn can be calculated by dividing the weight average molecular weight by the number average molecular weight.

[Polyamide block (A2)]
The polyamide block (A2) is a polyamide block composed of structural units that do not have a furan ring.

Examples of polyamides constituting the polyamide block (A2) include (A2-a) polyamides obtained by ring-opening polymerization of lactams (hereinafter sometimes simply referred to as "(A2-a) polyamides"); (A2-b) polyamides obtained by self-condensation of ω-aminocarboxylic acids (hereinafter sometimes simply referred to as "(A2-b) polyamides"); (A2-c) polyamides obtained by condensation polymerization of diamines and dicarboxylic acids (hereinafter sometimes simply referred to as "(A2-c) polyamides"); and copolymers obtained by copolymerization of two or more types of monomers constituting these polyamides. These polyamides may be used alone or in combination of two or more types.

(A2-a) Lactams used in the production of polyamides include, but are not limited to, pivalolactam, pyrrolidone, caprolactam, caprylolactam, enantholactam, undecalactam, dodecalactam (laurolactam), etc.

(A2-b) The ω-amino carboxylic acid used in the production of polyamide is not limited to the following, but examples thereof include ω-amino fatty acids which are ring-opening compounds of the above-mentioned lactams with water. Specific examples of ω-amino carboxylic acids include 6-aminocaproic acid, 11-aminoundecanoic acid, and 12-aminododecanoic acid. Other examples of ω-amino carboxylic acids include para-aminomethylbenzoic acid.

In addition, two or more types of monomers of the lactam or ω-aminocarboxylic acid may be used in combination and condensed.

The dicarboxylic acid (monomer) used in the production of (A2-c) polyamide is not limited to the following, but examples thereof include aromatic dicarboxylic acids, alicyclic dicarboxylic acids, and aliphatic dicarboxylic acids. The dicarboxylic acid used in the production of (A2-c) polyamide may be synthesized from a biological raw material.

Examples of aromatic dicarboxylic acids include, but are not limited to, terephthalic acid, isophthalic acid, 4,4'-biphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, diphenylether-4,4'-dicarboxylic acid, diphenoxyethane-4,4'-dicarboxylic acid, diphenoxybutane-4,4'-dicarboxylic acid, diphenylethane-4,4'-dicarboxylic acid, diphenylether-3,3'-dicarboxylic acid, diphenoxyether-3,3'-dicarboxylic acid, and diphenylethane-3,3'-dicarboxylic acid. Of these, terephthalic acid is preferred from the viewpoint of versatility.

Examples of alicyclic dicarboxylic acids include, but are not limited to, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 2,5-norbornenedicarboxylic acid, and 1,3-cyclopentanedicarboxylic acid.

Examples of aliphatic dicarboxylic acids include, but are not limited to, oxalic acid, malonic acid, dimethylmalonic acid, succinic acid, 2,2-dimethylsuccinic acid, 2,3-dimethylglutaric acid, 2,2-diethylsuccinic acid, 2,3-diethylglutaric acid, glutaric acid, 2,2-dimethylglutaric acid, adipic acid, 2-methyladipic acid, trimethyladipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, tetradecanedioic acid, hexadecanedioic acid, octadecanedioic acid, eicosane diacid, diglycolic acid, hydrogenated dimer acid, fumaric acid, maleic acid, itaconic acid, citraconic acid, dimer acid, etc.

Diamines (monomers) used in the production of polyamide (A2-c) include, but are not limited to, aromatic diamines, alicyclic diamines, linear aliphatic diamines, branched aliphatic diamines, etc. Diamines used in the production of polyamide (A2-c) may be synthesized from biological materials.

Examples of aromatic diamines include, but are not limited to, paraxylylenediamine, ortho-xylylenediamine, meta-xylylenediamine, para-diaminobenzene, meta-diaminobenzene, ortho-diaminobenzene, etc.

Examples of alicyclic diamines include, but are not limited to, 1,4-cyclohexanediamine, 1,3-cyclohexanediamine, 1,2-cyclohexanediamine, isophoronediamine, 4,4'-methylenebis(cyclohexylamine), 4,4'-methylenebis(2-methylcyclohexylamine), 1,3-cyclopentanediamine, etc.

Straight-chain aliphatic diamines include, but are not limited to, 1,2-ethylenediamine, 1,3-propylenediamine, 1,4-tetramethylenediamine, 1,5-pentamethylenediamine, 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, 1,8-octamethylenediamine, 1,9-nonamethylenediamine, 1,10-decamethylenediamine, 1,11-undecamethylenediamine, 1,12-dodecamethylenediamine, and 1,13-tridecamethylenediamine.

Examples of branched aliphatic diamines include, but are not limited to, 2-methylpentamethylenediamine (also called 2-methyl-1,5-diaminopentane), 2,2,4-trimethylhexamethylenediamine, 2,4,4-trimethylhexamethylenediamine, 2-methyloctamethylenediamine (also called 2-methyl-1,8-octanediamine), 2,4-dimethyloctamethylenediamine, etc.

The diamines and dicarboxylic acids as monomers described above may be condensed either individually or in combination of two or more.

The polyamide constituting the polyamide block (A2) may further contain units derived from a polyvalent carboxylic acid having three or more valences, such as trimellitic acid, trimesic acid, or pyromellitic acid, as necessary. The polyvalent carboxylic acid having three or more valences may be used alone or in combination of two or more kinds.

Specific examples of polyamides constituting the polyamide block (A2) include, but are not limited to, polyamide 4 (poly-α-pyrrolidone), polyamide 6 (polycaproamide), polyamide 11 (polyundecane amide), polyamide 12 (polydodecanamide), polyamide 46 (polytetramethylene adipamide), polyamide 56 (polypentamethylene adipamide), polyamide 66 (polyhexamethylene adipamide), polyamide 610 (polyhexamethylene sebacamide), polyamide 70 (polyhexamethylene sebacamide), polyamide 71 (polyhexamethylene sebacamide), polyamide 72 (polyhexamethylene sebacamide), polyamide 73 (polyhexamethylene sebacamide), polyamide 74 (polyhexamethylene sebacamide), polyamide 75 (polyhexamethylene sebacamide), polyamide 76 (polyhexamethylene sebacamide), polyamide 77 (polyhexamethylene sebacamide), polyamide 78 (polyhexamethylene sebacamide), polyamide 79 (polyhexamethylene sebacamide), polyamide 80 (polyhexamethylene sebacamide), polyamide 81 (polyhexamethylene sebacamide), polyamide 82 (polyhexamethylene sebacamide), polyamide 83 (polyhexamethylene sebacamide), polyamide 84 (polyhexamethylene sebacamide), polyamide 85 (polyhexamethylene sebacamide), polyamide 86 (polyhexamethylene sebacamide), polyamide 87 (polyhexamethylene sebacamide), polyamide 88 (polyhexamethylene sebacamide), polyamide 89 (polyhexamethylene sebacamide), polyamide 90 (polyhexamethylene sebacamide), polyamide 91 (polyhexamethylene sebacamide), polyamide 92 (polyhexamethylene sebacamide), polyamide 93 (polyhex Polyamide 612 (polyhexamethylene dodecamide), polyamide 116 (polyundecamethylene adipamide), polyamide TMHT (trimethylhexamethylene terephthalamide), polyamide 6T (polyhexamethylene terephthalamide), polyamide 2Me-5T (poly 2-methylpentamethylene terephthalamide), polyamide 9T (polynonamethylene terephthalamide), 2Me-8T (poly 2-methyloctamethylene terephthalamide), polyamide 6I (polyhexamethylene isophthalamide), poly Amide 6C (polyhexamethylenecyclohexanedicarboxamide), polyamide 2Me-5C (poly 2-methylpentamethylenecyclohexanedicarboxamide), polyamide 9C (polynonamethylenecyclohexanedicarboxamide), 2Me-8C (poly 2-methyloctamethylenecyclohexanedicarboxamide), polyamide PACM12 (polybis(4-aminocyclohexyl)methanediamide), polyamide dimethyl PACM12 (polybis(3-methylaminocyclohexyl)methanediamide) dodecamide, polyamide MXD6 (polymetaxylylene adipamide), polyamide 10T (polydecamethylene terephthalamide), polyamide 11T (polyundecamethylene terephthalamide), polyamide 12T (polydodecamethylene terephthalamide), polyamide 10C (polydecamethylene cyclohexane dicarboxamide), polyamide 11C (polyundecamethylene cyclohexane dicarboxamide), polyamide 12C (polydodecamethylene cyclohexane dicarboxamide), and the like.
The above "Me" represents a methyl group.

Among them, the polyamide constituting the polyamide block (A2) is preferably a crystalline polyamide. Examples of preferred crystalline polyamides include polyamide 46 (polytetramethylene adipamide), polyamide 66 (polyhexamethylene adipamide), polyamide 6T (polyhexamethylene terephthalamide), and polyamide 10T (polydecamethylene terephthalamide). Among them, polyamide 66 is particularly preferred from the viewpoint of versatility.

Preferred polyamide blocks (A2) include, for example, polyamide blocks having one or more dicarboxylic acid units selected from the group consisting of aliphatic dicarboxylic acid units and aromatic dicarboxylic acid units, and aliphatic diamine units; polyamide blocks having aliphatic dicarboxylic acid units, and one or more diamine units selected from the group consisting of aliphatic diamine units and aromatic diamine units.

More preferred examples of the polyamide block (A2) include a polyamide block having adipic acid units and 1,4-tetramethylenediamine units; a polyamide block having adipic acid units and 1,6-hexamethylenediamine units; a polyamide block having terephthalic acid units and 1,6-hexamethylenediamine units; a polyamide block having terephthalic acid units and 1,10-decamethylenediamine units, etc.

The above-mentioned polyamide block (A2) is merely one example of a preferred polyamide block (A2), and the preferred polyamide block (A2) is not limited to the above-mentioned one.

(Physical Properties of Polyamide Constituting Polyamide Block (A2))
The number average molecular weight of the polyamide constituting the polyamide block (A2) is preferably 500 to 5,000, more preferably 1,000 to 4,500, even more preferably 2,000 to 4,000, and particularly preferably 2,500 to 3,500. When the number average molecular weight of the polyamide constituting the polyamide block (A2) is within the above numerical range, the heat resistance and mechanical strength of the obtained molded article can be improved. In addition, the viscosity does not become too high, and the moldability is also excellent.

The weight average molecular weight of the polyamide constituting the polyamide block (A2) is preferably 1,000 or more and 20,000 or less, more preferably 1,200 or more and 18,000 or less, even more preferably 1,500 or more and 15,000 or less, and particularly preferably 2,000 or more and 10,000 or less. When the weight average molecular weight of the polyamide constituting the polyamide block (A2) is within the above numerical range, the heat resistance and mechanical strength of the obtained molded article can be improved. In addition, the viscosity does not become too high, and the moldability is also excellent.

The molecular weight distribution Mw/Mn of the polyamide constituting the polyamide block (A2) is not particularly limited, but is preferably 1.5 to 4.0, more preferably 1.8 to 3.5, and even more preferably 2.0 to 3.0. When the molecular weight distribution of the polyamide constituting the polyamide block (A1) is within the above numerical range, the heat resistance and mechanical strength of the obtained molded article can be improved. In addition, the viscosity does not become too high, and the moldability is also excellent.

The number average molecular weight and weight average molecular weight of the polyamide constituting the polyamide block (A2) are molecular weights calculated in terms of polymethyl methacrylate in molecular weight measurements by GPC. The molecular weight distribution Mw/Mn can be calculated by dividing the weight average molecular weight by the number average molecular weight.

[Molecular end]
The molecular ends of the block copolymer may be capped with a known end-capping agent.
Such an end-capping agent can also be added as a molecular weight regulator when producing a polyamide constituting each block from the dicarboxylic acid, the diamine, and, if necessary, at least one compound selected from the group consisting of the lactam and the aminocarboxylic acid.

Examples of end-capping agents include, but are not limited to, monocarboxylic acids, monoamines, acid anhydrides, monoisocyanates, monoacid halides, monoesters, monoalcohols, etc. Examples of acid anhydrides include, but are not limited to, phthalic anhydride, etc. These end-capping agents may be used alone or in combination of two or more.

Among these, monocarboxylic acids or monoamines are preferred as end-capping agents. By blocking the ends of the polyamide with an end-capping agent, the resulting polyamide composition tends to have better thermal stability.

The monocarboxylic acid that can be used as the end-capping agent may be any one that is reactive with amino groups that may be present at the terminals of the polyamide. Specific examples of the monocarboxylic acid include, but are not limited to, aliphatic monocarboxylic acids, alicyclic monocarboxylic acids, and aromatic monocarboxylic acids.
Examples of aliphatic monocarboxylic acids include, but are not limited to, formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecylic acid, myristic acid, palmitic acid, stearic acid, pivalic acid, and isobutyric acid.
Examples of alicyclic monocarboxylic acids include, but are not limited to, cyclohexanecarboxylic acid.
Examples of aromatic monocarboxylic acids include, but are not limited to, benzoic acid, toluic acid, α-naphthalenecarboxylic acid, β-naphthalenecarboxylic acid, methylnaphthalenecarboxylic acid, and phenylacetic acid.
These monocarboxylic acids may be used alone or in combination of two or more.

The monoamine usable as the end-capping agent may be any monoamine that is reactive with a carboxyl group that may be present at the end of the polyamide. Specific examples of the monoamine include, but are not limited to, aliphatic monoamines, alicyclic monoamines, and aromatic monoamines.
Examples of the aliphatic amine include, but are not limited to, methylamine, ethylamine, propylamine, butylamine, hexylamine, octylamine, decylamine, stearylamine, dimethylamine, diethylamine, dipropylamine, and dibutylamine.
Examples of the alicyclic amine include, but are not limited to, cyclohexylamine, dicyclohexylamine, and the like.
Examples of aromatic amines include, but are not limited to, aniline, toluidine, diphenylamine, naphthylamine, and the like.
These monoamines may be used alone or in combination of two or more.

Polyamide compositions containing block copolymers end-capped with an end-capping agent tend to have superior heat resistance, flowability, toughness, low water absorption, and rigidity.

The polyamide composition of the present embodiment may further contain, in addition to the block copolymer, other polyamides within the range that does not impair the effects of the present embodiment.
Other polyamides include, for example, the same polyamides as those exemplified as the polyamides constituting the polyamide block (A2) described above.

<Other additives>
The polyamide composition of the present embodiment may further contain other additives such as an antioxidant, an antistatic agent, a flame retardant, a flame retardant assistant, a heat stabilizer, a fibrous reinforcing material, a filler, and a pigment.
Examples of fibrous reinforcing materials include glass fibers, carbon fibers, and cellulose nanofibers.
Examples of the filler include talc, swelling clay minerals, silica, alumina, glass beads, graphite, fillers, and cellulose nanocrystals.
Examples of the pigment include titanium oxide and carbon black.

The content of other additives is preferably 5% by mass or less based on the total mass of the block copolymer.

<Method of producing polyamide composition>
The method for producing the polyamide composition of the present embodiment is not particularly limited, but examples thereof include a method in which polyamides (hereinafter also referred to as "polyamide prepolymers") constituting each polyamide block are each prepared, and then the polyamides (polyamide prepolymers) are block copolymerized.

A method for preparing a polyamide prepolymer includes, for example, a method of forming a salt of a polyamide constituting a polyamide block. Specifically, a method (solution polymerization method) of reacting a dicarboxylic acid, a diamine, and, if necessary, at least one compound selected from the group consisting of lactam and aminocarboxylic acid in water or an organic solvent to obtain a polyamide salt is exemplified. The amount of the solvent used is preferably 50 parts by mass or more, more preferably 100 parts by mass or more, per 100 parts by mass of the total of the dicarboxylic acid and diamine (if necessary, lactam and aminocarboxylic acid). The reaction temperature is preferably 50°C or more and 90°C or less under normal pressure, and is preferably 30°C or more and 60°C or less under pressurized conditions. The reaction time is preferably 0.5 hours or more and 5 hours or less, more preferably 1 hour or more and 3 hours or less, after the reaction temperature is reached.

Next, the polymerization reaction using the obtained salt of polyamide as a raw material may be carried out by melt polymerization at a temperature equal to or higher than the melting point of the obtained salt, or by solid-phase polymerization at a temperature lower than the melting point of the obtained salt. The pressure may be normal pressure or may be increased. By carrying out the above polymerization reaction, a polyamide block having an appropriate molecular weight is prepared.
When the reaction is carried out by melt polymerization, the reaction temperature is preferably from {(melting point of the resulting salt)+10° C.} to 240° C. In addition, the reaction time is preferably from 3 hours to 8 hours after the reaction temperature is reached. When the reaction is carried out by solid-phase polymerization, the reaction temperature is preferably from {(melting point of the resulting salt)−100° C.} to less than (the melting point of the resulting salt). In addition, the reaction time is preferably from 5 hours to 10 hours after the reaction temperature is reached.

To further increase the molecular weight, the polymerization reaction may be continued under normal pressure or in an inert gas atmosphere, or under reduced pressure. When the polymerization is continued under reduced pressure, it is preferable that the degree of reduction in pressure is 0.5 kPa or less.

When carrying out the polymerization reaction, it is preferable to use a catalyst in order to increase the polymerization rate. Examples of catalysts include phosphoric acid, phosphorous acid, hypophosphorous acid, and salts thereof. These may be used alone or in combination of two or more. The amount of catalyst used is preferably 5 mol % or less based on the total number of moles of monomers such as dicarboxylic acid and diamine.

The block copolymerization carried out by mixing two or more prepared polyamide blocks (polyamide prepolymers) may be carried out by melt polymerization at a temperature equal to or higher than the melting point of the resulting block copolymer, or by solid-phase polymerization at a temperature lower than the melting point of the resulting block copolymer. The pressure may be normal pressure or may be increased. When melt polymerization is carried out, the reaction temperature is preferably from {(melting point of the resulting block copolymer) + 10°C} to 240°C. The reaction time is preferably from 3 hours to 8 hours after the reaction temperature is reached. When solid-phase polymerization is carried out, the reaction temperature is preferably from {(melting point of the resulting block copolymer) - 100°C} to less than the melting point of the resulting block copolymer. The reaction time is preferably from 5 hours to 10 hours after the reaction temperature is reached.

In order to further increase the molecular weight, the block copolymerization reaction of the polyamide block (polyamide prepolymer) may be continued under normal pressure or in an inert gas atmosphere, or under reduced pressure. When polymerization is continued under reduced pressure, the degree of reduction in pressure is preferably 0.5 kPa or less.

When carrying out a block copolymerization reaction of polyamide blocks (polyamide prepolymers), it is preferable to use a catalyst in order to increase the polymerization rate. Examples of catalysts include those similar to those mentioned above. The amount of catalyst used is preferably 5 mol % or less based on the total number of moles of polyamide blocks (polyamide prepolymers).

A terminal blocking agent may be used for the purpose of adjusting the degree of polymerization, suppressing decomposition and coloring, etc. Examples of terminal blocking agents include those exemplified in the above "molecular terminals." The amount of terminal blocking agent used can be appropriately selected according to the desired molecular weight of the polyamide block (polyamide prepolymer).

<Physical Properties of Polyamide Composition>
In the polyamide composition of the present embodiment, the content of the biomass-derived component is preferably 25% by mass or more, more preferably 50% by mass or more, based on the total mass of the block copolymer. By having the content of the biomass-derived component be equal to or more than the above lower limit, the environmental benefits are greater.

The number average molecular weight of the polyamide composition of this embodiment is preferably 5,000 or more and 20,000 or less, more preferably 6,000 or more and 18,000 or less, even more preferably 7,000 or more and 15,000 or less, and particularly preferably 7,500 or more and 11,000 or less. When the number average molecular weight of the polyamide composition of this embodiment is within the above numerical range, the heat resistance and mechanical strength of the obtained molded article can be improved. In addition, the viscosity does not become too high, and the moldability is also excellent.

The weight average molecular weight of the polyamide composition of this embodiment is preferably 7,000 or more and 5,0000 or less, more preferably 8,000 or more and 40,000 or less, even more preferably 10,000 or more and 30,000 or less, and particularly preferably 13,000 or more and 23,000 or less. When the weight average molecular weight of the polyamide composition of this embodiment is within the above numerical range, the heat resistance and mechanical strength of the obtained molded article can be improved. In addition, the viscosity does not become too high, and the moldability is also excellent.

The molecular weight distribution Mw/Mn of the polyamide composition of this embodiment is not particularly limited, but is preferably 1.5 to 4.5, more preferably 2.0 to 4.0, and even more preferably 2.5 to 3.5. When the molecular weight distribution of the polyamide composition is within the above numerical range, the heat resistance and mechanical strength of the obtained molded article can be improved. In addition, the viscosity does not become too high, and the moldability is also excellent.

The number average molecular weight and weight average molecular weight of the polyamide composition are molecular weights calculated in terms of polymethyl methacrylate in molecular weight measurements by GPC. The molecular weight distribution Mw/Mn can be calculated by dividing the weight average molecular weight by the number average molecular weight.

The glass transition temperature Tg of the polyamide composition of this embodiment is preferably 90°C or higher, more preferably 95°C or higher, and even more preferably 100°C or higher. When the glass transition temperature of the polyamide composition of this embodiment is equal to or higher than the above lower limit, the heat resistance of the resulting molded article can be made more excellent. On the other hand, the upper limit of the glass transition temperature Tg is not particularly limited, but is preferably 200°C or lower, more preferably 180°C or lower, and even more preferably 160°C or higher, for example.

The melting point Tm of the polyamide composition of this embodiment is preferably 200°C or higher, more preferably 220°C or higher, and even more preferably 230°C or higher. When the melting point of the polyamide composition of this embodiment is equal to or higher than the above lower limit, the heat resistance of the resulting molded article can be made more excellent. On the other hand, the upper limit of the melting point Tm is not particularly limited, but in order to more effectively prevent the temperature difference from the thermal decomposition temperature from becoming small and to further improve molding processability, it is preferably 350°C or lower, more preferably 300°C or lower, and even more preferably 260°C or lower.

The crystallization (melting) enthalpy ΔH of the polyamide composition of this embodiment is preferably 20 J/g or more, and more preferably 40 J/g or more. When the melting enthalpy is equal to or more than the above lower limit, the crystallinity is higher, and the mechanical properties of the molded article can be improved.

The melting point and fusion enthalpy tend to be higher by increasing the molecular skeleton, molecular weight, and charge amount of the polyamide block (A2) used in the block copolymerization (i.e., the content of the polyamide block (A2) in the block copolymer).
Specifically, the melting point and fusion enthalpy tend to be higher by, for example, increasing the types of dicarboxylic acid units and diamine units constituting the polyamide block (A2); using, for the polyamide constituting the polyamide block (A2), a polyamide other than a polyamide consisting of aliphatic dicarboxylic acid units and aliphatic diamine units, such as polyamide 66 (particularly, a polyamide having aromatic dicarboxylic acid units and/or aromatic diamine units); increasing the number of repeating units (i.e., the length of the molecular chain) of the polyamide block (A2); or increasing the amount of polyamide block (A2) added during the production of the polyamide composition.

The glass transition temperature, melting point and enthalpy of fusion can be measured, for example, using the method described in the Examples below.

In the polyamide composition of the present embodiment, the content of the polyamide block (A1) in the block copolymer is preferably 50 mass% or more, and more preferably 50 mass% or more and 70 mass% or less, based on the total mass of the block copolymer.
On the other hand, when the number average molecular weight of the polyamide constituting the polyamide block (A2) in the block copolymer is 3,000 or more, the content of the polyamide block (A1) in the block copolymer may be less than 50 mass% based on the total mass of the block copolymer.
The content of the polyamide block (A1) in the block copolymer can be calculated, for example, from the blending amount of each polyamide prepolymer used in producing the polyamide composition.

In addition, when the content of polyamide block (A1) in the block copolymer is 50% by mass and the content of polyamide block (A2) is 50% by mass, i.e., the content ratio of polyamide block (A1) to polyamide block (A2) is 1:1, the crystallinity of the block copolymer can be increased, and therefore it is preferable that the number average molecular weight of polyamide block (A2) is larger than the number average molecular weight of polyamide block (A1).

In addition, when the number average molecular weights of the polyamide constituting the polyamide block (A1) and the polyamide constituting the polyamide block (A2) in the block copolymer are approximately the same (for example, the difference in number average molecular weight is about ±500), the crystallinity of the block copolymer can be increased, so that the content of the polyamide block (A2) is preferably greater than the content of the polyamide block (A1).

<Molded body>
The molded article of the present embodiment is produced by molding the above-mentioned polyamide composition.
The molded article of the present embodiment has excellent mechanical properties by using the above-mentioned polyamide composition.

The molded article of this embodiment can be obtained by molding the above-mentioned polyamide composition using a known molding method such as injection molding, extrusion molding, or blow molding.

The molded article of this embodiment can be suitably used as an automobile part, or an electrical or electronic part.

Examples of automotive parts include shift levers, base plates used as seats for gearboxes, etc., and engine covers.

Examples of electrical and electronic components include connectors, LED reflectors, switches, sensors, sockets, capacitors, jacks, fuse holders, relays, coil bobbins, resistors, and housings for ICs and LEDs.

The polyamide composition described above can be processed into molded articles such as films, sheets, and fibers by known film-forming and spinning methods.

Specific examples of the films and sheets include speaker diaphragms, film capacitors, insulating films, and various packaging films.
Specific examples of the fibers include airbag fabrics, filters, and the like.

The present invention will be described in detail below with specific examples and comparative examples, but the present invention is not limited to the following examples.

<Method of measuring physical properties>
[Physical Properties 1]
(Content of biomass-derived components)
The content of biomass-derived components was calculated using the following formula.

"Biomass-derived component content (mass%)"
= (dry mass of the biomass-derived component blended) / (dry mass of the obtained block copolymer) × 100

[Physical Properties 2]
(Weight average molecular weight and number average molecular weight)
The weight average molecular weight and number average molecular weight of the polyamide prepolymer and the polyamide composition were measured by GPC under the following conditions.

(Measurement conditions)
GPC model: Tosoh HPLC-8320
Columns: 1 KG 4A and 2 KF-606M (both manufactured by Shodex) were used after solvent replacement with hexafluoroisopropanol (HFIP).
Eluent: HFIP in which 0.4% by mass of sodium trifluoroacetate is dissolved
Flow rate: 0.3mL/min
Sample concentration: 1.0 mg/mL
Column temperature: 40°C
Detector: RI (differential refractive index) detector Injection amount of sample solution: 60 μL

The molecular weight at each elution time was calculated from the elution curve of monodisperse polymethyl methacrylate (PMMA), and the weight average molecular weight and number average molecular weight were calculated as PMMA-equivalent molecular weights.

[Physical Properties 3]
(Glass transition temperature Tg)
The glass transition temperatures (Tg) of the polyamide constituting the polyamide block (A1), the polyamide constituting the polyamide block (A2), and the block copolymer were measured under the following conditions.

(Measurement conditions)
Model: NETZSCH DSC3500
Measurement method: Measurement was performed in a nitrogen atmosphere at temperatures ranging from -20°C to 240°C with a temperature change of 20K/min, and the data from the second scan was read as the glass transition temperature (Tg).

[Physical Properties 4]
(Melting point Tm)
The melting point Tm was measured in accordance with JIS-K7121 using a DSC3500 manufactured by NETZSCH Co., Ltd. Specifically, the measurement was performed as follows.
First, in a nitrogen atmosphere, about 5 mg of a sample was heated from 30°C to 220°C at 20°C/min, held for 1 minute, and then cooled to 30°C at 20°C/min. Then, the operation of heating from 30°C to 300°C, holding for 1 minute, and then cooling to 30°C was repeated twice. The heating/cooling rates at this time were both 20°C/min. Among these, the highest peak temperature of the endothermic peak (melting peak) appearing during the second heating was taken as Tm (°C), and the exothermic peak appearing during the second cooling was taken as the crystallization peak.

<Evaluation method>
[Evaluation 1]
(Crystalline)
The crystallinity was evaluated by measuring the crystallization enthalpy ΔH of the polyamide composition. The crystallization enthalpy ΔH of the polyamide composition was measured using a DSC3500 manufactured by NETZSCH in accordance with JIS-K7121. Specifically, the measurement was performed as follows.
First, in a nitrogen atmosphere, about 5 mg of a sample was heated from 30°C to 220°C at 20°C/min, held for 1 minute, and then cooled to 30°C at 20°C/min. Then, the operation of heating from 30°C to 300°C, holding for 1 minute, and then cooling to 30°C was repeated twice. The heating/cooling rates at this time were both 20°C/min. Among these, the highest peak temperature of the endothermic peak (melting peak) appearing during the second heating was taken as Tm (°C), and the exothermic peak appearing during the second cooling was taken as the crystallization peak. The crystallization peak temperature was taken as Tc, and the crystallization peak area was taken as the crystallization enthalpy ΔH (J/g).
The crystallinity was evaluated from the measured crystallization enthalpy ΔH based on the following criteria.

(Evaluation Criteria)
◎: Crystallization enthalpy ΔH is 70 J/g or more. ○: Crystallization enthalpy ΔH is 40 J/g or more and less than 70 J/g. △: Crystallization enthalpy ΔH is 20 J/g or more and less than 40 J/g. ×: Crystallization enthalpy ΔH is less than 20 J/g.

[Evaluation 2]
(Mechanical properties: tensile strength)
The polyamide compositions obtained in the Examples and Comparative Examples were molded into multipurpose test pieces (A type) by injection molding in accordance with ISO3167 to obtain molded articles.
Using each molded body (multipurpose test piece), a tensile test was carried out in accordance with ISO 527 at a temperature of 120° C. and a tensile speed of 5 mm/min to measure the tensile strength (MPa).
The mechanical properties were evaluated from the measured tensile strength values based on the following evaluation criteria.

(Evaluation Criteria)
◎: Tensile strength is 100 MPa or more. ○: Tensile strength is 80 MPa or more and less than 100 MPa. △: Tensile strength is 30 MPa or more and less than 80 MPa. ×: Tensile strength is less than 20 J/g.

<Ingredients>
The following reagents were purchased and used without purification.
2,5-Furandicarboxylic acid (Distributor: Fujifilm Wako Pure Chemical Industries, Ltd.)
Adipic acid (Distributor: Tokyo Chemical Industry Co., Ltd.)
Metaxylylenediamine (Distributor: Tokyo Chemical Industry Co., Ltd.)
Hexamethylenediamine (Distributor: Tokyo Chemical Industry Co., Ltd.)
Sodium hydrogen phosphate monohydrate (Distributor: Fujifilm Wako Pure Chemical Industries, Ltd.)
Ethylbenzene (Sold by Kanto Chemical Co., Ltd.)

<Production of polyamide composition>
[Example 1]
(Production of polyamide composition PA-a1)
(1) Production of polyamide prepolymer constituting polyamide block (A1-a1) 5.0 g of 2,5-furandicarboxylic acid (2,5-FDCA), 3.7 g of metaxylylenediamine (MXD), and 0.14 g of sodium hydrogen phosphate monohydrate were placed in a glass round-bottom flask, and vacuum-nitrogen replacement was performed three times. Ethylbenzene (10 mL) was added, and polymerization reaction was performed at 120° C. for 5.5 hours under a nitrogen atmosphere to obtain an MXDF prepolymer. The number average molecular weight of the obtained MXDF prepolymer was 400, the weight average molecular weight was 1900, and the molecular weight distribution was 4.9.

(2) Production of polyamide prepolymer constituting polyamide block (A2-a1) 2.0 g of adipic acid, 1.33 g of hexamethylenediamine, and 0.66 g of sodium hydrogen phosphate monohydrate were polymerized in a nitrogen atmosphere at 180° C. for 7.5 hours to obtain a polyamide 66 prepolymer. The number average molecular weight of the obtained polyamide 66 prepolymer was 3,000, the weight average molecular weight was 6,900, and the molecular weight distribution was 2.3.

(3) Production of polyamide composition PA-a1 (block copolymerization)
MXDF/66 block copolymer was obtained by solid-phase polymerization of 0.1 g of MXDF prepolymer and 0.1 g of polyamide 66 prepolymer under reduced pressure at 210° C. for 8 hours. The number average molecular weight of the obtained MXDF/66 block copolymer was 6,400, the weight average molecular weight was 18,300, the molecular weight distribution was 2.9, the glass transition temperature was 101° C., and the melting point was 240° C.

[Examples 2 to 13 and Comparative Examples 1 to 3]
(Polyamide compositions PA-a2 to PA-a8 and PA-b1 to PA-b3)
Each polyamide composition was obtained in the same manner as in Example 1, except that the components of the polyamide composition were as shown in Tables 1 to 3 below.

The results of the evaluation using the evaluation method described above are shown in Tables 1 to 3.

As shown in Tables 1 to 3, the polyamide compositions PA-a1 to PA-a13 (Examples 1 to 13), which contain a block copolymer having a polyamide block (A1) with a furan ring and a polyamide block (A2) without a furan ring, exhibited good crystallinity and good mechanical properties when molded.

On the other hand, in the polyamide composition PA-b1 (Comparative Example 1) containing only MXDF polymer, which is a polyamide having a furan ring, as the polyamide, and the polyamide composition PA-b3 (Comparative Example 3) containing a random copolymer having a polyamide block (A1) having a furan ring and a polyamide block (A2) not having a furan ring, both the crystallinity and the mechanical properties when molded were poor.
In addition, the polyamide composition PA-b2 (Comparative Example 2), which contained only polyamide 66 polymer, a polyamide not having a furan ring, had good crystallinity, but had poor mechanical properties when molded into a molded article.

The polyamide composition of this embodiment can provide a polyamide composition that has crystallinity and has excellent mechanical properties when molded into a molded article. The molded article of this embodiment is made by molding the polyamide composition and has excellent mechanical properties.

Claims (11)

A polyamide composition comprising a block copolymer having a polyamide block (A1) having a furan ring and a polyamide block (A2) not having a furan ring. The polyamide composition according to claim 1, wherein the polyamide block (A1) has 2,5-furandicarboxylic acid units and one or more diamine units selected from the group consisting of aromatic diamine units, alicyclic diamine units, and aliphatic diamine units. The polyamide composition according to claim 1 or 2, wherein the polyamide block (A1) has 2,5-furandicarboxylic acid units and aromatic diamine units. The polyamide composition according to any one of claims 1 to 3, wherein the polyamide block (A2) has one or more dicarboxylic acid units selected from the group consisting of aliphatic dicarboxylic acid units and aromatic dicarboxylic acid units, and aliphatic diamine units. The polyamide composition according to any one of claims 1 to 3, wherein the polyamide block (A2) has an aliphatic dicarboxylic acid unit and one or more diamine units selected from the group consisting of an aliphatic diamine unit and an aromatic diamine unit. The polyamide composition according to any one of claims 1 to 5, wherein the number average molecular weight of the polyamide constituting the polyamide block (A1) is 300 or more and 6,000 or less. The polyamide composition according to any one of claims 1 to 6, wherein the number average molecular weight of the polyamide constituting the polyamide block (A2) is 500 or more and 5,000 or less. The polyamide composition according to any one of claims 1 to 7, wherein the number average molecular weight of the polyamide composition is 5,000 or more and 2,0000 or less. The polyamide composition according to any one of claims 1 to 8, wherein the glass transition temperature Tg of the polyamide composition is 90°C or higher and 200°C or lower. The polyamide composition according to any one of claims 1 to 9, wherein the melting point Tm of the polyamide composition is 200°C or higher and 350°C or lower. A molded article obtained by molding the polyamide composition according to any one of claims 1 to 10.