Polyamide, molded articles and films thereof, and methods for manufacturing the polyamide

Abstract

This invention provides polyamides and polyamide films with superior heat resistance, softness, and rubber elasticity. The invention relates to a polyamide and a polyamide film containing the polyamide, wherein the polyamide contains units formed of aliphatic dicarboxylic acids (A) with 18 or more carbon atoms, units formed of aliphatic diamines (B) with 18 or more carbon atoms, units formed of aromatic dicarboxylic acids (C) with 12 or fewer carbon atoms, and units formed of aliphatic diamines (D) with 12 or fewer carbon atoms, and has a melting point of 240°C or higher, a crystal melting enthalpy of 20 J / g or higher, and an elongation recovery rate of 50% or higher in a hysteresis test.

Description

Technical Field

[0001] This invention relates to a polyamide with excellent heat resistance, softness, and rubber elasticity, as well as molded articles and films made therefrom, and a method for manufacturing the polyamide. Background Technology

[0002] Polyamides, with their high flexibility and rubber-like elasticity, are widely used in pipes and hoses, everyday footwear, and sealing materials. These polyamides typically contain polyether and polyester components to impart flexibility and rubber-like elasticity. In recent years, research has been conducted on applying these polyamides to automotive parts, peripheral components for electronic devices, and battery materials, where higher heat resistance is required.

[0003] To obtain polyamides with high heat resistance, the polymerization temperature must be increased. However, if the polymerization temperature is increased, there is a problem that the polyether and polyester components used to impart flexibility may decompose, resulting in a decrease in molecular weight and consequently, insufficient performance.

[0004] As a polyamide that does not use polyether or polyester components, Patent Document 1 discloses a polyamide formed from terephthalic acid, 1,10-decanediamine, dimeric acid, and dimeridine. Patent Document 2 discloses a polyamide formed from adipic acid, 1,4-butanediamine, dimeric acid, and dimeridine.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: International Publication No. 2020 / 085360

[0008] Patent Document 2: Japanese Patent Publication No. 2014-506614 Summary of the Invention

[0009] However, although the polyamides in Patent Documents 1 and 2 have improved heat resistance, they have problems with insufficient improvement in softness and rubber elasticity.

[0010] This invention was made to solve the above-mentioned problems, and its purpose is to provide a polyamide with superior heat resistance, softness and rubber elasticity.

[0011] The inventors discovered that by reacting an aromatic dicarboxylic acid (C) with 12 or fewer carbon atoms with an aliphatic diamine (D) with 12 or fewer carbon atoms to obtain a reaction product, and then reacting the reaction product with an aliphatic dicarboxylic acid (A) with 18 or more carbon atoms and an aliphatic diamine (B) with 18 or more carbon atoms to polymerize it, the above-mentioned objective can be achieved, thus completing the present invention.

[0012] That is, the main idea of ​​this invention is as follows.

[0013] (1) A polyamide containing a unit formed of an aliphatic dicarboxylic acid (A) having 18 or more carbon atoms, a unit formed of an aliphatic diamine (B) having 18 or more carbon atoms, a unit formed of an aromatic dicarboxylic acid (C) having 12 or fewer carbon atoms, and a unit formed of an aliphatic diamine (D) having 12 or fewer carbon atoms, and having a melting point of 240°C or higher, a crystal melting enthalpy of 20 J / g or higher, and an elongation recovery rate of 50% or higher in a hysteresis test.

[0014] (2) According to the polyamide described in (1), wherein the aliphatic dicarboxylic acid (A) with 18 or more carbon atoms is a dimer acid.

[0015] (3) The polyamide according to (1) or (2), wherein the aliphatic diamine (B) having 18 or more carbon atoms is a dimeric diamine.

[0016] (4) The polyamide according to any one of (1) to (3), wherein the aromatic dicarboxylic acid (C) having 12 or fewer carbon atoms is terephthalic acid.

[0017] (5) The polyamide according to any one of (1) to (4), wherein the aliphatic diamine (D) having 12 or fewer carbon atoms is 1,10-decanediamine.

[0018] (6) The polyamide according to any one of (1) to (5), wherein the total content of units formed of aliphatic dicarboxylic acids (A) having 18 or more carbon atoms and units formed of aliphatic diamines (B) having 18 or more carbon atoms is 10 to 90 by mass relative to the total monomer components constituting the above-mentioned polyamide.

[0019] (7) The polyamide according to any one of (1) to (6), wherein the total content of units formed of aliphatic dicarboxylic acids (A) having 18 or more carbon atoms and units formed of aliphatic diamines (B) having 18 or more carbon atoms is 20 to 80 by mass relative to the total monomer components constituting the above-mentioned polyamide.

[0020] (8) The polyamide according to any one of (1) to (7), wherein the aliphatic dicarboxylic acid (A) having 18 or more carbon atoms has 30 to 40 carbon atoms.

[0021] The aliphatic diamines (B) with 18 or more carbon atoms mentioned above have 30 to 40 carbon atoms.

[0022] The aromatic dicarboxylic acids (C) with 12 or fewer carbon atoms mentioned above have 6 to 12 carbon atoms.

[0023] The aliphatic diamines (D) with fewer than 12 carbon atoms mentioned above have 6 to 12 carbon atoms.

[0024] (9) The polyamide according to any one of (1) to (8), wherein the content of the unit formed from the aliphatic dicarboxylic acid (A) having 18 or more carbon atoms is 3 to 45% by mass relative to the total monomer content constituting the polyamide.

[0025] The content of the units formed by the above-mentioned aliphatic diamines (B) having 18 or more carbon atoms is 3 to 45% by mass relative to the total monomer content constituting the above-mentioned polyamide.

[0026] The content of the units formed by aromatic dicarboxylic acids (C) with 12 or fewer carbon atoms is 3 to 45% by mass relative to the total monomer content constituting the polyamide.

[0027] The content of the units formed by the aliphatic diamines (D) with 12 or fewer carbon atoms is 3 to 52% by mass relative to the total monomer content constituting the polyamide.

[0028] (10) A molded body containing any one of (1) to (9) polyamide.

[0029] (11) A membrane containing any one of (1) to (9) polyamide.

[0030] (12) A method for manufacturing a polyamide, wherein the following components are reacted and polymerized:

[0031] Aliphatic dicarboxylic acids (A) with 18 or more carbon atoms,

[0032] Aliphatic diamines (B) with 18 or more carbon atoms,

[0033] The reaction product of an aromatic dicarboxylic acid (C) with 12 or fewer carbon atoms and an aliphatic diamine (D) with 12 or fewer carbon atoms.

[0034] (13) A method for manufacturing a polyamide, wherein an aliphatic dicarboxylic acid (A) having 18 or more carbon atoms is pre-reacted with an aliphatic diamine (B) having 18 or more carbon atoms, and then reacts with the reaction product of an aromatic dicarboxylic acid (C) having 12 or fewer carbon atoms and an aliphatic diamine (D) having 12 or fewer carbon atoms to polymerize the polyamide.

[0035] (14) The polyamide described in any one of (1) to (9) is manufactured according to the method for manufacturing polyamide described in (12) or (13).

[0036] According to the present invention, a polyamide with excellent heat resistance, softness and rubber elasticity can be provided.

[0037] The polyamide film of the present invention exhibits excellent softness and rubber elasticity because it forms hard and soft segments. Attached Figure Description

[0038] Figure 1A A graph showing the hysteresis curve of Example 1.

[0039] Figure 1B A graph showing the hysteresis curve of Example 6.

[0040] Figure 2 A graph showing the hysteresis curve of Comparative Example 1.

[0041] Figure 3 This is a schematic diagram illustrating the hysteresis curve used to explain the calculation method for the hysteresis loss rate. Detailed Implementation

[0042] The polyamide of the present invention contains units formed of aliphatic dicarboxylic acids (A) having 18 or more carbon atoms (hereinafter sometimes referred to as component (A)), units formed of aliphatic diamines (B) having 18 or more carbon atoms (hereinafter sometimes referred to as component (B)), units formed of aromatic dicarboxylic acids (C) having 12 or fewer carbon atoms (hereinafter sometimes referred to as component (C)), and units formed of aliphatic diamines (D) having 12 or fewer carbon atoms (hereinafter sometimes referred to as component (D)). In the polyamide, components (A) to (D) are contained as monomer components (or monomer residues). Therefore, "units formed of aliphatic dicarboxylic acids (A) having 18 or more carbon atoms" may also simply be "aliphatic dicarboxylic acid (A) monomers having 18 or more carbon atoms" or residues thereof. Similarly, "units formed of aliphatic diamines (B) having 18 or more carbon atoms" may also simply be "aliphatic diamine (B) monomers having 18 or more carbon atoms" or residues thereof. "Units formed from aromatic dicarboxylic acids (C) with 12 or fewer carbon atoms" may also be represented simply as "monomers of aromatic dicarboxylic acids (C) with 12 or fewer carbon atoms" or their residues. "Units formed from aliphatic diamines (D) with 12 or fewer carbon atoms" may also be represented simply as "monomers of aliphatic diamines (D) with 12 or fewer carbon atoms" or their residues.

[0043] The aliphatic dicarboxylic acid (A) with 18 or more carbon atoms used in the polyamide of the present invention is preferably an aliphatic dicarboxylic acid formed entirely of hydrocarbons except for the carboxyl group. Examples include hexadecanedicarboxylic acid (18 carbon atoms), octadecanedicarboxylic acid (20 carbon atoms), and dimer acid (36 carbon atoms). Among these, aliphatic dicarboxylic acids with 20 or more carbon atoms are preferred due to their high flexibility, and dimer acid is more preferred. Dimer acid can also be obtained by adding two molecules selected from unsaturated fatty acids such as oleic acid and linolenic acid. These two molecules can be molecules of the same type or molecules of different types. Dimer acid can be a dicarboxylic acid with unsaturated bonds. Since it is not easy to color, it is preferred to be a dicarboxylic acid that has been hydrogenated to make all bonds saturated. Component (A) can be used alone or in combination with two or more of the above-mentioned components.

[0044] From the viewpoint of further improving the heat resistance, softness and rubber elasticity of polyamide and the film containing the polyamide, the carbon number of component (A) is preferably 20 to 40, more preferably 30 to 40, and even more preferably 34 to 38.

[0045] From the viewpoint of further improving the heat resistance, softness, and rubber elasticity of polyamide and films containing such polyamide, the content of component (A) is preferably 3 to 45% by mass, more preferably 5 to 45% by mass, particularly preferably 10 to 45% by mass, and even more preferably 10 to 40% by mass. This content refers to the content of residues of component (A) and is a proportion relative to the total monomer components constituting the polyamide (or the total amount of such residues). When the polyamide contains two or more components (A), these total amounts are acceptable within the above range.

[0046] The aliphatic diamine (B) with 18 or more carbon atoms used in the polyamide of the present invention is preferably an aliphatic dicarboxylic acid, consisting entirely of hydrocarbons except for the amino group. Examples include octadecanediamine (18 carbon atoms), eicosanediamine (20 carbon atoms), and dimeramide (36 carbon atoms). Dimeramide is preferred. By using dimeramide, the overall flexibility of the polymer can be effectively improved even with a resin composition that is relatively small compared to other monomers. Dimeramide is typically manufactured by reacting a dimer acid with ammonia, followed by dehydration, nitrification, and reduction. Dimeramide can be a diamine with unsaturated bonds; since it is not easily colored, a diamine that has been hydrogenated to make all bonds saturated is preferred. Component (B) can be one of the above-mentioned components alone or in combination of two or more.

[0047] From the viewpoint of further improving the heat resistance, softness and rubber elasticity of polyamide and the film containing the polyamide, the carbon number of component (B) is preferably 20 to 40, more preferably 30 to 40, and even more preferably 34 to 38.

[0048] From the viewpoint of further improving the heat resistance, softness, and rubber elasticity of polyamide and films containing such polyamide, the content of component (B) is preferably 3 to 45% by mass, more preferably 5 to 45% by mass, particularly preferably 10 to 45% by mass, and even more preferably 10 to 40% by mass. This content refers to the residue content of component (B) and is a proportion relative to the total monomer components constituting the polyamide (or the total amount of such residues). When the polyamide contains two or more components (B), these total amounts are acceptable within the above range.

[0049] Examples of aromatic dicarboxylic acids (C) with 12 or fewer carbon atoms used in the polyamide of this invention include terephthalic acid (8 carbon atoms), isophthalic acid (8 carbon atoms), and phthalic acid (8 carbon atoms). Among these, aromatic dicarboxylic acids with 8 or more carbon atoms are preferred because they readily improve heat resistance, softness, and rubber elasticity. Terephthalic acid is more preferably used. Component (C) may be used alone or in combination with two or more of the above-mentioned components.

[0050] From the viewpoint of further improving the heat resistance, softness and rubber elasticity of polyamide and the film containing the polyamide, the carbon number of component (C) is preferably 4 to 12, more preferably 6 to 12, and even more preferably 6 to 10.

[0051] From the viewpoint of further improving the heat resistance, softness, and rubber elasticity of polyamide and films containing such polyamide, the content of component (C) is preferably 3 to 45% by mass, more preferably 5 to 45% by mass, particularly preferably 5 to 40% by mass, and even more preferably 8 to 35% by mass. This content refers to the residue content of component (C) and is a proportion relative to the total monomer components constituting the polyamide (or the total amount of these residues). When the polyamide contains two or more components (C), these total amounts are acceptable within the above range.

[0052] Examples of aliphatic diamines (D) with 12 or fewer carbon atoms used in the polyamide of the present invention include 1,12-dodecanediamine (12 carbon atoms), 1,10-decanediamine (10 carbon atoms), 1,9-nonanediamine (9 carbon atoms), 1,8-octanediamine (8 carbon atoms), and 1,6-hexanediamine (6 carbon atoms). Since diamines with 6 or more carbon atoms are preferred as they readily improve heat resistance, softness, and rubber elasticity, diamines with 8 or more carbon atoms are more preferred, and 1,10-decanediamine is even more preferred. Component (D) may be used alone or in combination with two or more of the above-mentioned components.

[0053] From the viewpoint of further improving the heat resistance, softness and rubber elasticity of polyamide and the film containing the polyamide, the carbon number of component (D) is preferably 4 to 12, more preferably 6 to 12, and even more preferably 8 to 12.

[0054] From the viewpoint of further improving the heat resistance, softness, and rubber elasticity of polyamide and films containing such polyamide, the content of component (D) is preferably 3 to 52% by mass, more preferably 5 to 50% by mass, particularly preferably 5 to 40% by mass, and even more preferably 10 to 40% by mass. This content refers to the residue content of component (D) and is a proportion relative to the total monomer components constituting the polyamide (or the total amount of these residues). When the polyamide contains two or more components (D), these total amounts are acceptable within the above range.

[0055] It can be inferred that in the polyamide of the present invention, units formed of aliphatic dicarboxylic acids (A) with 18 or more carbon atoms and units formed of aliphatic diamines (B) with 18 or more carbon atoms form soft segments, while units formed of aromatic dicarboxylic acids (C) with 12 or fewer carbon atoms and units formed of aliphatic diamines (D) with 12 or fewer carbon atoms form hard segments. Through the formation of such a phase-separated structure of hard and soft segments, the polyamide can be considered to possess excellent heat resistance, as well as significantly superior softness and rubber elasticity. Specifically, in the polyamide of the present invention, since the hard segments act as crosslinking points for rubber, the soft segments can freely stretch and contract, thus ensuring heat resistance while also exhibiting softness and rubber elasticity (especially rubber elasticity). Examples of combinations of components (C) and (D) include terephthalic acid and butanediamine, terephthalic acid and 1,9-nonanediamine, terephthalic acid and 1,10-decanediamine, and terephthalic acid and 1,12-dodecanediamine; among these, terephthalic acid and 1,10-decanediamine are preferred. By using terephthalic acid and 1,10-decanediamine, the hard segments readily become highly crystalline segments, thus promoting the formation of a phase-separated structure between the hard and soft segments, resulting in superior softness and rubber elasticity. "Rubber" is used in the context of a substance that exhibits the property of undergoing localized deformation due to external force but recovering its original shape upon removal of the force.

[0056] From the viewpoint of further improving the heat resistance, softness, and rubber elasticity of polyamide and films containing such polyamide, the total content of units formed by aliphatic dicarboxylic acids (A) with 18 or more carbon atoms and units formed by aliphatic diamines (B) with 18 or more carbon atoms in the polyamide is preferably 10 to 90% by mass, more preferably 15 to 80% by mass, particularly preferably 20 to 80% by mass, and even more preferably 30 to 75% by mass. This total content is the total content of residues of component (A) and residues of component (B), and is a proportion relative to the total monomer components constituting the polyamide (or the total amount of these residues).

[0057] In the polyamide of the present invention, polyethers or polyesters that are easily decomposed during polymerization are preferably used. Examples of such polyethers include polyethylene glycol, polyoxypropylene glycol, polyoxytetramethylene glycol, and polyethylene oxide-polyoxypropylene glycol. Examples of such polyesters include polyethylene adipate, polytetramethylene adipate, and polyethylene sebacate. When using polyethers or polyesters, decomposition may occur if the polymerization temperature is high.

[0058] From the viewpoint of further improving the heat resistance, flexibility, and rubber elasticity of polyamide and films containing such polyamide, the total content of the polyether component and the polyester component is preferably 2% by mass or less, more preferably 1% by mass or less, and particularly preferably 0.1% by mass or less. The lower limit of this total content range is typically 0% by mass. This total content refers to the residue content of the polyether component and the polyester component, and is a proportion relative to the total monomer components (or the total amount of these residues) constituting the polyamide. The polyether component and the polyester component are components that constitute part of the polyamide through covalent bonds with the polyamide, and are not merely doped into the polyamide.

[0059] To adjust the degree of polymerization, inhibit product decomposition, and suppress coloring, the polyamide of this invention may also contain an end-capping agent. Examples of end-capping agents include monocarboxylic acids such as acetic acid, lauric acid, benzoic acid, and stearic acid, and monoamines such as octylamine, cyclohexylamine, aniline, and stearylamine. One of the above-mentioned end-capping agents may be used alone, or two or more may be used in combination. The content of the end-capping agent is not particularly limited, but is generally 0 to 10 mol% relative to the total molar amount of the dicarboxylic acid and diamine.

[0060] The polyamide of the present invention may also contain additives. Examples of additives include fibrous reinforcing materials such as glass fiber and carbon fiber; fillers such as talc, swelling clay minerals, silica, alumina, glass beads, and graphite; pigments such as titanium dioxide and carbon black; antioxidants; antistatic agents; flame retardants; and flame retardant additives. Additives may be included during polymerization or after polymerization through melt mixing or other methods.

[0061] In the polyamide of the present invention, the melting point, which serves as an indicator of heat resistance, must be 240°C or higher. From the viewpoint of further improving the heat resistance, flexibility, and rubber elasticity of the polyamide and the film containing the polyamide, it is preferably 270°C or higher, and more preferably 300°C or higher. If the melting point is too low, the heat resistance decreases. This melting point is typically 400°C or lower (especially 350°C or lower).

[0062] In the polyamide of the present invention, from the viewpoint of further improving the heat resistance, flexibility, and rubber elasticity of the polyamide and the film containing the polyamide, the enthalpy of melting, which serves as an indicator of the crystallinity of the hard segments, is preferably 20 J / g or more, more preferably 23 J / g or more, and even more preferably 25 J / g or more. Higher crystallinity of the hard segments promotes the formation of a phase-separated structure between the hard and soft segments, thereby improving flexibility and rubber elasticity. If the enthalpy of melting is too low, flexibility and / or rubber elasticity decrease. The enthalpy of melting is typically 120 J / g or less (particularly 90 J / g or less).

[0063] The polyamide of the present invention has particularly superior softness and rubber elasticity compared to the random polyamide described later.

[0064] In the polyamide of the present invention, the elongation recovery rate, which serves as an indicator of softness, must be 50% or more, and preferably 55% or more from the viewpoint of further improving the heat resistance, softness, and rubber elasticity of the polyamide and the film containing the polyamide. If the elongation recovery rate is too low, the softness decreases. This elongation recovery rate is typically 100% or less (especially 90% or less).

[0065] The elongation recovery rate of the polyamide of the present invention is more effectively demonstrated by comparison with conventional polyamides (sometimes simply referred to as random polyamides in this specification) that have the same monomer composition as the polyamide of the present invention but whose monomer components (components (A) to (D)) are randomly arranged. For example, the elongation recovery rate of the polyamide of the present invention is greater than that of the random polyamide. The increase rate (%) of the elongation recovery rate of the polyamide of the present invention, based on the elongation recovery rate of the random polyamide, is generally 10% or more, preferably 20% or more, and more preferably 40% or more. This increase rate of elongation recovery rate is generally 300% or less (particularly 200% or less). The increase rate of elongation recovery rate is the value (%) expressed as "{(X1-Y1) / Y1}×100" when X1 represents the elongation recovery rate of the polyamide of the present invention and Y1 represents the elongation recovery rate of the random polyamide. Random polyamides are obtained by a method identical to that used in the polyamide manufacturing method of the present invention, except that the raw materials (total monomer components) are added together and polymerized.

[0066] In the polyamide of the present invention, the Shore D hardness, which serves as an indicator of flexibility, is preferably 75 or less, more preferably 65 or less. This Shore D hardness is typically 1 or more (especially 2 or more).

[0067] Since the Shore D hardness of the polyamide of the present invention also depends on the monomer composition of the polyamide, it is more effectively demonstrated by comparison with atactic polyamides having the same monomer composition as the polyamide of the present invention. For example, the Shore D hardness of the polyamide of the present invention is less than that of atactic polyamides. The reduction rate (%) of the Shore D hardness of the polyamide of the present invention, based on the Shore D hardness of the atactic polyamide, is generally 2% or more, preferably 5% or more, and more preferably 6.5% or more. This reduction rate of Shore D hardness is generally 70% or less (particularly 50% or less). The reduction rate of Shore D hardness is the value (%) expressed as "{(Y2-X2) / Y2}×100" when X2 represents the Shore D hardness of the polyamide of the present invention and Y2 represents the Shore D hardness of the atactic polyamide.

[0068] In the polyamide of the present invention, a lower hysteresis loss rate indicates higher rubber elasticity. Compared with conventional polyamides produced by random polymerization of monomers, the polyamide of the present invention exhibits a low hysteresis loss rate due to the control of the chain lengths of hard and soft segments in the polymer. In the polyamide of the present invention, the hysteresis loss rate is preferably 90% or less, more preferably 85% or less, and even more preferably 80% or less. This hysteresis loss rate is typically 10% or more (particularly 30% or more).

[0069] Since the hysteresis loss rate of the polyamide of the present invention also depends on the monomer composition of the polyamide, it is more effectively demonstrated by comparison with random polyamides with the same monomer composition as the polyamide of the present invention. For example, the hysteresis loss rate of the polyamide of the present invention is smaller than that of random polyamides. The reduction rate (%) of the hysteresis loss rate of the polyamide of the present invention, based on the hysteresis loss rate of the random polyamide, is generally 2% or more, preferably 4% or more, and more preferably 5.5% or more. This reduction rate of hysteresis loss rate is generally 40% or less (particularly 30% or less). The reduction rate of hysteresis loss rate is the value (%) expressed as "{(Y3-X3) / Y3}×100" when X3 represents the hysteresis loss rate of the polyamide of the present invention and Y3 represents the hysteresis loss rate of the random polyamide.

[0070] The polyamide of the present invention can be obtained by further reacting components (C) and (D), and components (A) and (B). For example, the polyamide of the present invention can be obtained by reacting an aromatic dicarboxylic acid (C) having 12 or fewer carbon atoms with an aliphatic diamine (D) having 12 or fewer carbon atoms to obtain a reaction product, and then further reacting the reaction product with an aliphatic dicarboxylic acid (A) having 18 or more carbon atoms and an aliphatic diamine (B) having 18 or more carbon atoms and polymerizing it. In detail, the polyamide of the present invention can be obtained by further reacting components (C) and (D) with an aliphatic diamine (B) having 18 or more carbon atoms.

[0071] Ingredients (A),

[0072] Component (B), and

[0073] The reaction products of component (C) and component (D)

[0074] It is obtained by reaction and polymerization.

[0075] In this manufacturing method, components (A) and (B) can be used in an unreacted state or in a reacted state (i.e., in the form of the reaction products). For example, the polyamide of the present invention can also be obtained by pre-reacting components (A) and (B), and then reacting the reaction product of components (A) and (B) with the reaction product of components (C) and (D) and polymerizing them. More specifically, the polyamide of the present invention can be obtained by...

[0076] The reaction products of component (A) and component (B), and

[0077] The reaction products of component (C) and component (D)

[0078] It is obtained by reaction and polymerization.

[0079] From the viewpoint of further improving the heat resistance, softness and rubber elasticity of polyamide and the film containing the polyamide, components (A) and (B) are preferably used in a state in which they react with each other (i.e., in the form of the reaction products).

[0080] In this invention, polymerization is carried out as described above, thereby obtaining a polyamide composed of hard segments containing components (C) and (D) and soft segments containing components (A) and (B), unlike conventional polyamides which are randomly polymerized from components (A) to (D). From the viewpoint of containing both hard and soft segments, conventional polyamides are "random polyamides," while the polyamide of this invention can be called a "block polyamide."

[0081] In the manufacturing method of the present invention, by adjusting the monomer ratio [(C) / (D)] of the aromatic dicarboxylic acid (C) with 12 or fewer carbon atoms and the aliphatic diamine (D) with 12 or fewer carbon atoms, the chain length of the obtained reaction product can be controlled. As a result, the softness and rubber elasticity of the obtained polyamide can be controlled. In order to further improve the softness and rubber elasticity, the molar ratio [(C) / (D)] is preferably set to 45 / 55 to 60 / 40, and more preferably to 45 / 55 to 55 / 45.

[0082] In the manufacturing process of the polyamide of the present invention, the method for producing the reaction product of an aromatic dicarboxylic acid (C) having 12 or fewer carbon atoms and an aliphatic diamine (D) having 12 or fewer carbon atoms (hereinafter sometimes simply referred to as "method X for producing the reaction product") is not particularly limited. For example, a method of adding component (D) by heating to a temperature above the melting point of component (D) and below the melting point of component (C) to maintain component (C) in a powder state can be cited. For example, when terephthalic acid and 1,10-decanediamine are used as components (C) and (D) respectively, the heating temperature can be 100 to 240°C (especially 140 to 200°C). The addition of component (D) is preferably carried out continuously, for example, preferably for 1 to 10 hours (especially 1 to 5 hours).

[0083] The reaction product of component (C) and component (D) can be in the form of salts of component (C) and component (D), or in the form of their condensate (or oligomer or prepolymer), or in the form of their composite.

[0084] When component (A) and component (B) are reacted beforehand, there is no particular limitation on the method of reacting an aliphatic dicarboxylic acid (A) with an aliphatic diamine (B) having 18 or more carbon atoms. For example, a method of reacting at a temperature of 80 to 150°C (especially 100 to 150°C) for 0.5 to 3 hours can be cited.

[0085] The reaction products of components (A) and (B) can also be in the form of salts, condensates (or oligomers or prepolymers), or complexes, just like the reaction products of components (C) and (D).

[0086] In the manufacturing process of the polyamide of the present invention, the polymerization method is not particularly limited. For example, a method of polymerization at a temperature below (preferably below) the melting point of the hard-segment polymer (i.e., a polyamide formed only of components (C) and (D) constituting the hard segments) can be cited. Specifically, polymerization is carried out by heating to a temperature below the melting point of the hard-segment polymer (i.e., a polyamide formed only of components (C) and (D) constituting the hard segments), removing condensation water from the system, and maintaining this temperature under a nitrogen flow. By performing polymerization in this way, polymerization can be carried out in a state where the hard segments do not melt and only the soft segments melt. The method of polymerization at a temperature below the melting point of the hard-segment polymer is particularly effective in the polymerization of high-melting-point polyamides above 280°C, where the polymerization temperature is high and decomposition is easy.

[0087] The term "melting point of a hard-segment polymer" refers to the melting point of a polyamide formed by fully polymerizing only components (C) and (D) that constitute the hard segments. "Melting point of a hard-segment polymer" is, for example, the melting point of a polyamide formed by fully polymerizing only components (C) and (D) using the method described in International Publication No. 2013 / 042541. Specifically, "melting point of a hard-segment polymer" is the melting point of a polyamide (hard-segment polymer) obtained by a method comprising a step (i) of obtaining a reaction product from components (C) and (D) and a step (ii) of polymerizing the obtained reaction product. In the manufacturing process of the hard-segment polymer, in step (i), components (C) and (D) are heated to a temperature above and below the melting point of component (D), and component (D) is added while maintaining component (C) in a powder state, thereby obtaining the reaction product. In step (i), for example, when terephthalic acid and 1,10-decanediamine are used as components (C) and (D) respectively, the heating temperature can be 100–240°C (preferably 140–200°C, particularly 170°C). The addition of component (D) is preferably carried out continuously, for example, preferably for 1–10 hours (preferably 1–5 hours, particularly 2.5 hours). In the manufacture of the hard-segment polymer, in step (ii), the reaction product obtained in the solid phase of step (i) is sufficiently heated to maintain this solid phase state for polymerization (i.e., solid-phase polymerization). In step (ii), for example, when terephthalic acid and 1,10-decanediamine are used as components (C) and (D) respectively, the heating temperature (i.e., polymerization temperature) can be 220–300°C (preferably 240–280°C, particularly 260°C), and the heating time (i.e., polymerization time) can be 1–10 hours (preferably 3–7 hours, particularly 5 hours). Processes (i) and (ii) are preferably carried out in an airflow such as nitrogen-inactive gas. For example, when terephthalic acid and 1,10-decanediamine are used as components (C) and (D) respectively, the melting point of the "hard-segment polymer" is typically 315°C.

[0088] Therefore, the following method can be used, for example, when manufacturing the polyamide of the present invention. First, using only components (C) and (D) constituting the polyamide, polymerization is carried out more fully through the above-described steps (i) and (ii) to obtain a polyamide (i.e., a hard-segment polymer). Next, the melting point of the obtained polyamide is determined. The method for determining the melting point is not particularly limited; for example, it can be determined by a differential scanning calorimeter. Subsequently, by the above-described method X for manufacturing reaction products, component (C) is reacted with component (D) to obtain a reaction product, and then the reaction product is further reacted with components (A) and (B) at a temperature below the melting point of the hard-segment polymer to carry out polymerization, thereby manufacturing the polyamide of the present invention. When dimer acid, dimeridine, terephthalic acid, and 1,10-decanediamine are used as components (A) to (D), respectively, the polymerization temperature can be 220 to 300°C (preferably 240 to 280°C, particularly 260°C). At this point, there is no particular limitation on the polymerization time as long as sufficient polymerization can be carried out; for example, it can be 1 to 10 hours (preferably 3 to 7 hours, especially 5 hours).

[0089] In the manufacturing method of the present invention, a catalyst may also be used as needed. Examples of catalysts include phosphoric acid, phosphorous acid, hypophosphorous acid, or their salts. The content of the catalyst is not particularly limited, but is generally 0 to 2 mol% relative to the total molar amount of dicarboxylic acid and diamine.

[0090] In the manufacturing method of the present invention, organic solvents or water may be added as needed.

[0091] In the manufacturing method of the present invention, polymerization can be carried out in a closed system or at atmospheric pressure. When carried out in a closed system, the pressure rises due to monomer volatilization or the generation of condensation water, so it is preferable to appropriately control the pressure. On the other hand, when the monomer used has a high boiling point, and the monomer will not flow out of the system even without pressure, polymerization can be carried out at atmospheric pressure. For example, in combinations of dimer acids, dimeramines, terephthalic acid, and decanediamine, polymerization can be carried out at atmospheric pressure.

[0092] In the manufacturing method of the present invention, in order to prevent oxidative deterioration, polymerization is preferably carried out in a nitrogen environment or under vacuum.

[0093] Polymerized polyamides can be extruded into strips and made into granules, or they can be made into granules by thermal cutting or underwater cutting.

[0094] In the manufacturing method of the present invention, solid-state polymerization can also be performed after polymerization to further increase the molecular weight. Solid-state polymerization is particularly effective in situations where the viscosity at the time of polymerization is high, making operation difficult. Solid-state polymerization is preferably carried out by heating at a temperature lower than the melting point of the resin composition for 30 minutes or more under the flow of an inactive gas or under reduced pressure, and more preferably for heating for 1 hour or more. The melting point of the resin composition can be the same temperature as the "melting point of the hard-segment polymer" described above.

[0095] The polyamide of this invention can be molded into molded articles by injection molding, extrusion molding, blow molding, sintering molding, etc. Among these methods, injection molding is preferred due to its significant improvement in mechanical properties and formability. The injection molding machine is not particularly limited; examples include screw-type inline injection molding machines and plunger-type injection molding machines. The polyamide, heated and melted within the cylinder of the injection molding machine, is measured with each injection. It is injected into the mold in a molten state, cooled and solidified to a predetermined shape, and then removed from the mold as a molded article. The heater temperature during injection molding is preferably set above the melting point.

[0096] The molded article of the present invention may contain the polyamide of the present invention as described above, or may further contain other polymers. The content of the polyamide of the present invention in the molded article is generally 50% by mass or more relative to the total amount of the molded article, preferably 70% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more.

[0097] When heating and melting the polyamide of the present invention, it is preferable to use thoroughly dried granules. If the granules contain a high moisture content, foaming will occur in the cylinder of the injection molding machine, making it difficult to obtain the optimal molded part. The moisture content of the granules used for injection molding is preferably less than 0.3 parts by weight relative to 100 parts by weight of polyamide, and more preferably less than 0.1 parts by weight.

[0098] The polyamide of this invention can be used in automotive parts such as fuel pipes, brake pipes, intake and exhaust system parts, intake and exhaust system piping, damping materials, and cooling pipes; electrical and electronic parts such as pipes, sheets, and connectors; gears; valves; oil trays; cooling fans; fuel tanks with radiators; cylinder heads; cans; hoses; soles of athletic shoes; medical catheters; straps for wearable devices such as smartwatches; protective cases; industrial pipes; cables; cable ties; drone parts; packaging; shaped materials; injection molded products; monofilaments for 3D printing or fishing lines; fibers, etc.

[0099] The polyamide of the present invention is particularly preferred for use as a membrane.

[0100] The membrane of the present invention may contain the polyamide described above, or may further contain other polymers. The content of the polyamide of the present invention in the membrane is generally 50% by mass or more relative to the total membrane volume, preferably 70% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more.

[0101] The membrane of the present invention is melt-mixed at 240–340°C for 3–15 minutes, then extruded into a sheet using a T-die. The extruded sheet is then pressed onto a roller with a temperature adjusted to -10–80°C for cooling, thereby producing an unstretched film. The unstretched film can be further stretched. The resulting unstretched film can be used in its unstretched state, but is generally used as a stretched film. Stretching is preferably performed in a uniaxial or biaxial direction, more preferably biaxial stretching. Examples of stretching methods include simultaneous stretching and successive stretching.

[0102] As an example of simultaneous biaxial stretching, a method can be described that involves simultaneously biaxially stretching an unstretched film, followed by heat-setting. Stretching is preferably performed at 30–150°C, with both the width direction (hereinafter sometimes referred to as “TD”) and length direction (hereinafter sometimes referred to as “MD”) set at 1.5–5 times. Heat-setting is preferably performed at 150–300°C for several seconds, with a relaxation rate of a few percent of the TD. Before simultaneous biaxial stretching, a pre-stretch of approximately 1–1.2 times the film length can also be applied.

[0103] As an example of the successive biaxial stretching method, a method can be described where the unstretched film is heat-treated by roller heating, infrared heating, etc., then stretched in the longitudinal direction, followed by continuous transverse stretching and heat-fixing. The longitudinal stretching is preferably performed at 30–150°C and is set to 1.5–5 times the original strength. The transverse stretching is the same as the longitudinal stretching, preferably set at 30–150°C. The transverse stretching is preferably set to 1.5 times or more. The heat-fixing treatment is preferably performed at 150–300°C for several seconds, with a relaxation rate of a few percent of the TD (Transverse Term).

[0104] In membrane manufacturing apparatus, to prevent resin from accumulating on the surfaces of the cylinder, the melting section of the barrel, the metering section, the single tube, the filter, the T-mold, etc., it is preferable to perform a process to reduce their surface roughness. As a method to reduce surface roughness, for example, modification with a low-polarity substance can be employed. Alternatively, for example, methods such as vapor deposition of silicon nitride or diamond-like carbon can be employed.

[0105] Methods for stretching membranes include, for example, planar successive biaxial stretching, planar simultaneous biaxial stretching, and tubular stretching. Among these, from the viewpoint of improving the thickness accuracy of the membrane and making the membrane's molecular weight (MD) uniform, the planar simultaneous biaxial stretching method is preferred.

[0106] Examples of tensioning devices used in simultaneous biaxial tensioning in a planar manner include screw-type tenter frames, pantograph-type tenter frames, and linear motor-driven clamp-type tenter frames.

[0107] Examples of known heat treatment methods after stretching include blowing hot air, irradiating with infrared radiation, and irradiating with microwaves. Among these, blowing hot air is preferred because it allows for uniform and precise heating.

[0108] To improve the thermal stability during film formation, prevent degradation of film strength or elongation, and prevent film degradation caused by oxidation or decomposition during use, the film of the present invention preferably contains a heat stabilizer. Examples of heat stabilizers include hindered phenolic heat stabilizers, hindered amine heat stabilizers, phosphorus-based heat stabilizers, sulfur-based heat stabilizers, and difunctional heat stabilizers.

[0109] Examples of hindered phenolic heat stabilizers include Irganox 1010 (registered trademark) (manufactured by BASF Japan, pentaerythritol tetratetra[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]), Irganox 1076 (registered trademark) (manufactured by BASF Japan, octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), Cyanox 1790 (registered trademark) (manufactured by SOLVAY, 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanuric acid), Irganox 1098 (registered trademark) (manufactured by BASF Japan, N,N'-(hexane-1,6-diyl)bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide]), and Sumilizer. GA-80 (registered trademark) (manufactured by Sumitomo Chemical Co., Ltd., 3,9-bis[2-{3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy}-1,1-dimethylethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane).

[0110] As a hindered amine heat stabilizer, an example is Nylostab S-EED (registered trademark) (manufactured by Clariant Japan, N,N'-bis-2,2,6,6-tetramethyl-4-piperidinyl-1,3-phenylenediamide).

[0111] Examples of phosphorus-based heat stabilizers include Irgafos168 (registered trademark) (manufactured by BASF Japan, tris(2,4-di-tert-butylphenyl) phosphite), Irgafos12 (registered trademark) (manufactured by BASF Japan, 6,6',6”-[azatri(ethoxy)]tris(2,4,8,10-tetra-tert-butyldibenzo[d,f][1,3,2]dioxophosphatane)), Irgafos38 (registered trademark) (manufactured by BASF Japan, bis(2,4-di-tert-butyl)-6-methylphenyl) ethyl phosphite), ADKSTAB329K (registered trademark) (manufactured by ADEKA, tris(mono-dinonylphenyl) phosphite), and ADKSTAB... PEP36 (registered trademark) (manufactured by ADEKA, bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol-diphosphite), Hostanox P-EPQ (registered trademark) (manufactured by Clariant, tetra(2,4-di-tert-butylphenyl)-4,4'-biphenyl diphosphite), GSY-P101 (registered trademark) (manufactured by Sakai Chemical Industry Co., Ltd., tetra(2,4-di-tert-butyl-5-methylphenyl)-4,4'-biphenyl diphosphite), Sumilizer GP (registered trademark) (manufactured by Sumitomo Chemical Co., Ltd., 6-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propoxy}-2,4,8,10-tetra-tert-butyldibenzo[d,f][1,3,2]-dioxophosphatane).

[0112] Examples of sulfur-based heat stabilizers include DSTP "Yoshitomi" (registered trademark) (manufactured by Mitsubishi Chemical Co., Ltd., chemical formula: distearate thiodipropionate) and Seenox 412S (registered trademark) (manufactured by SHIPRO Chemical Co., Ltd., pentaerythritol tetra-(3-dodecyl thiodipropionate)).

[0113] Examples of difunctional heat stabilizers include Sumilizer GM (registered trademark) (manufactured by Sumitomo Chemical Co., Ltd., 2-tert-butyl-6-(3-tert-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate) and Sumilizer GS (registered trademark) (manufactured by Sumitomo Chemical Co., Ltd., 2-[1-(2-hydroxy-3,5-di-tert-pentylphenyl)ethyl]-4,6-di-tert-pentylphenyl acrylate).

[0114] From the viewpoint of preventing membrane strength degradation, hindered phenolic heat stabilizers are preferred. The thermal decomposition temperature of the hindered phenolic heat stabilizer is preferably 320°C or higher, more preferably 350°C or higher. Examples of hindered phenolic heat stabilizers with a thermal decomposition temperature of 320°C or higher include Sumilizer GA-80. Furthermore, if the hindered phenolic heat stabilizer has an amide bond, membrane strength degradation can be prevented. Examples of hindered phenolic heat stabilizers with an amide bond include Irganox 1098. Additionally, by using a difunctional heat stabilizer in conjunction with the hindered phenolic heat stabilizer, membrane strength degradation can be further reduced.

[0115] These heat stabilizers can be used alone or in combination of two or more. For example, if a hindered phenolic heat stabilizer and a phosphorus-based heat stabilizer are used together, pressure rise in the feed filter during membrane fabrication can be prevented, while membrane strength degradation can also be prevented. Furthermore, if a hindered phenolic heat stabilizer, a phosphorus-based heat stabilizer, and a difunctional heat stabilizer are used together, pressure rise in the feed filter during membrane fabrication can be prevented, while membrane strength degradation can be further reduced.

[0116] As a combination of hindered phenolic heat stabilizer and phosphorus-based heat stabilizer, a combination of Sumilizer GA-80 or Irganox 1098 and Hostanox P-EPQ or GSY-P101 is preferred. As a combination of hindered phenolic heat stabilizer, phosphorus-based heat stabilizer and difunctional heat stabilizer, a combination of Sumilizer GA-80 or Irganox 1098, Hostanox P-EPQ or GSY-P101, and Sumilizer GS is preferred, and a combination of Sumilizer GA-80, GSY-P101 and Sumilizer GS is more preferred.

[0117] The content of the heat stabilizer in the membrane of the present invention is preferably set to 0.01 to 2 parts by mass relative to 100 parts by mass of polyamide (A), and more preferably to 0.04 to 1 part by mass. By setting the content of the heat stabilizer to 0.01 to 2 parts by mass, thermal decomposition can be suppressed more effectively. In addition, when two or more heat stabilizers are used together, it is preferable that the individual content of each heat stabilizer and the total content of the heat stabilizers are both within the above-mentioned range.

[0118] In order to achieve good smoothness, the membrane of the present invention may also contain lubricant particles. Examples of lubricant particles include inorganic particles such as silica, alumina, titanium dioxide, calcium carbonate, kaolinite, and barium sulfate, or organic particles such as acrylic resin particles, melamine resin particles, silicone resin particles, and cross-linked polystyrene particles.

[0119] The membrane of the present invention may contain various additives as needed, without impairing the effects of the invention. Examples of additives include pigments, dyes, and other colorants; color-resistant agents; antioxidants (different from the aforementioned heat stabilizers); weather-resistant modifiers; flame retardants; plasticizers; release agents; reinforcing agents; modifiers; antistatic agents; ultraviolet absorbers; antifogging agents; and various polymers. Examples of pigments include titanium dioxide. Examples of weather-resistant modifiers include benzotriazole compounds. Examples of flame retardants include brominated or phosphorus-based flame retardants. Examples of reinforcing agents include talc. It should be noted that the above-mentioned additives can be added at any stage of membrane manufacturing.

[0120] In the membrane of the present invention, treatments to improve the adhesion of its surface may be performed as needed. Examples of methods to improve adhesion include corona treatment, plasma treatment, acid treatment, and flame treatment.

[0121] Various coating agents can be applied to the surface of the membrane of the present invention to impart functions such as easy adhesion, antistatic properties, mold release properties, and gas barrier properties.

[0122] In the stretched membrane of the present invention, inorganic materials such as metals or their oxides, other types of polymers, paper, fabrics, non-woven fabrics, wood, etc. may also be laminated.

[0123] The membrane of the present invention has excellent heat resistance. The melting point, which is used as an indicator of heat resistance, must be above 240°C, preferably above 250°C, more preferably above 270°C, and even more preferably above 300°C.

[0124] Furthermore, the elastic modulus of the membrane of the present invention, which serves as an indicator of its flexibility, is preferably 2500 MPa or less, more preferably 2000 MPa or less, and even more preferably 1500 MPa or less.

[0125] In addition, the membrane of the present invention has a positive dielectric loss tangent, a low dielectric constant and excellent dielectric properties, and thus excellent insulation properties.

[0126] The resulting membrane can be made into a single sheet or wound onto a winding roller to form a membrane roll. From a productivity point of view for use in various applications, it is preferable to form it into a membrane roll. When forming the membrane roll, it can also be cut into the required width.

[0127] The film obtained in the above manner exhibits excellent heat resistance, flexibility, and rubber elasticity. Therefore, the film of the present invention can be used as: packaging material for pharmaceuticals; packaging material for food such as autoclaved foods; packaging material for electronic components such as semiconductor packaging; electrical insulation material for motors, transformers, cables, wires, multilayer printed wiring boards, etc.; dielectric material for capacitors, etc.; magnetic tape material for cassette tapes, data storage tapes suitable for digital data storage, videotapes, etc.; protective material for solar cell substrates, liquid crystal panels, conductive films, glass, digital labels, other display devices, etc.; electronic substrate material for LED mounting substrates, organic EL substrates, flexible printed wiring boards, flexible flat cables, flexible antennas, speaker diaphragms, etc.

[0128] Heat-resistant protective films for flexible printed wiring, heat-resistant shielding tapes, etc.; heat-resistant adhesive films for heat-resistant barcode labels, various industrial engineering tapes, etc.; heat-resistant reflectors; heat-resistant release films; heat-conducting films; films for semiconductor processes such as dicing tapes, dicing tape integrated chip bonding films (dicing-chip bonding films), dicing tape integrated wafer back protection films, and grinding back films; molding and finishing materials for in-mold forming, film insertion forming, vacuum forming, and air-forming; interlayer adhesives for laminated or multilayer printed wiring boards, adhesive sheets for flexible printed wiring boards, adhesive sheets for flexible flat cables, adhesive sheets for protective films, etc.; impact-absorbing materials such as tube coatings, wire coatings, impact-absorbing films, and sealing films; photographic films; agricultural materials; medical materials; civil engineering and construction materials; filter membranes, household and industrial materials; and membranes for fiber materials. The membrane of the present invention can be used for the above-described uses in an unstretched state, or it can be used for the above-described uses after being stretched as a stretched membrane.

[0129] Example

[0130] The present invention will be specifically described below through examples, but the present invention is not limited thereto.

[0131] A. Evaluation Methods

[0132] The physical properties of polyamide and polyamide films were determined using the following methods.

[0133] (1) Resin composition

[0134] The obtained particles or powder were subjected to high-energy nuclear magnetic resonance (NMR) analysis using a high-energy NMR spectrometer (ECA-500NMR, manufactured by JEOL Ltd., Japan). 1 ¹H-NMR analysis was performed, and the results were obtained from the peak intensities of each copolymer component (decomposition energy: 500 MHz, solvent: a mixed solvent of deuterated trifluoroacetic acid and deuterated chloroform in a volume ratio of 4 / 5, temperature: 23 °C). In Table 2, the resin composition is presented as the final composition, expressed as a mass ratio.

[0135] (2) Melting point, enthalpy of fusion of crystals

[0136] Several mg of the obtained granules or powder were taken and heated to 350°C using a differential scanning calorimeter (DSC-7, Perkin Elmer) at a heating rate of 20°C / min. The temperature was then maintained at 350°C for 5 minutes, cooled to 25°C at a cooling rate of 20°C / min, and then further heated to 20°C at a heating rate of 20°C / min.

[0137] The melting point is taken as the peak of the thermal peak during reheating, and the heat from the endothermic peak is taken as the enthalpy of fusion of the crystal. The enthalpy of fusion of the crystal is calculated from the peak area over the temperature range from the start to the end of melting.

[0138] (3) Shore D hardness (softness)

[0139] After thoroughly drying the obtained granules or powder, they are molded using an injection molding machine at a cylinder temperature of 340°C and a metal mold temperature of 80°C to produce test pieces (dumbbell-shaped pieces) for general physical property testing according to ISO standards. The obtained test pieces are then used for testing according to ASTM D 2240.

[0140] (4) Elongation recovery rate (softness), hysteresis loss rate (rubber elastic modulus)

[0141] Dumbbell-shaped test pieces were prepared in the same manner as described in (3) above, and the elongation recovery rate and hysteresis loss rate were determined using an INTESCO 2020 testing machine. At 23°C, with a clamping distance of 55 mm and a tensile test speed of 5 mm / min, the sample was stretched for 11 mm and immediately returned to its original shape at the same speed. The residual strain A (mm) when the stress became zero was calculated. The hysteresis curves of Examples 1 and 6 and Comparative Example 1 are shown below. Figure 1A , Figure 1B and Figure 2 .

[0142] The elongation recovery rate is calculated using the residual strain A, according to the following formula.

[0143] Elongation recovery rate (%) = (11-A) / 11×100

[0144] Furthermore, the hysteresis curve obtained is used to calculate the following formula.

[0145] Hysteresis loss rate (%) = Area (Oabcd) / Area (OabeO) × 100

[0146] For example, in Figure 3 In the diagram, area (Oabcd) is the area of ​​the region indicated by the dashed line (vertical dashed line), and area (OabeO) is the area of ​​the region indicated by the solid line (horizontal solid line). Figure 3 This is a schematic diagram illustrating the hysteresis curve used to explain the calculation method for the hysteresis loss rate.

[0147] (5) Tensile breaking strength, tensile elongation at break (flexibility) and tensile modulus of elasticity of the membrane

[0148] The test was conducted according to JIS K 7127 at an environment of 20°C and 65% humidity. The sample size was 10mm × 150mm, the initial distance between the clamps was 100mm, and the tensile speed was set to 500mm / min.

[0149] (6) Membrane water absorption rate

[0150] Vacuum drying was performed at 50°C for 24 hours, and the weight was measured. The sample was then immersed in pure water at 23°C. After 24 hours, the surface moisture was wiped off, and the weight was measured again. The water absorption rate was determined from the weight change before and after immersion.

[0151] (7) Thermal shrinkage rate of the membrane

[0152] According to JIS K7133, the shrinkage rate of the film after heat treatment at 200°C for 15 minutes was measured.

[0153] (8) Dielectric properties of the film

[0154] The relative permittivity and dielectric loss tangent at 5.8 GHz were determined using the resonant cavity perturbation method. The sample size was set to 2 mm × 50 mm.

[0155] B. Raw materials

[0156] The raw materials used are as follows.

[0157] • Dimer acid: Croda's Pripol 1009

[0158] ·Terephthalic acid:

[0159] • Dimeric diamine: Priamine 1075 manufactured by Croda

[0160] · Sebacdiamine:

[0161] Sodium hypophosphite:

[0162] • Heat stabilizer: Sumitomo Chemical Co., Ltd. Sumilizer GA-80

[0163] Example 1

[0164] • Preparation of reaction products

[0165] In a belt mixer-type reaction apparatus, 23.5 parts by mass of terephthalic acid and 0.1 parts by mass of sodium hypophosphite monohydrate were added. Under nitrogen-sealed conditions, the mixture was stirred at 30 rpm and heated to 170°C. Then, maintaining the temperature at 170°C and the stirring speed at 30 rpm, 24.4 parts by mass of 1,10-decanediamine heated to 100°C was continuously added over 2.5 hours (continuous injection method) to obtain the reaction product. The molar ratio of the raw material monomers was terephthalic acid: 1,10-decanediamine = 50.0: 50.0.

[0166] Production of polyamide

[0167] 26.7 parts by mass of dimer acid and 25.3 parts by mass of dimeric diamine were added to a reaction vessel equipped with a heating and stirring mechanism. After stirring at 100°C for 1 hour, 47.9 parts by mass of the above reaction product were added while stirring.

[0168] Subsequently, the mixture was heated to 260°C while stirring, and the condensation water was removed from the system. Polymerization was then carried out for 5 hours at atmospheric pressure and 260°C under a nitrogen stream. During the polymerization process, the system remained in a suspension state.

[0169] After polymerization, the material is discharged, cut, and dried to obtain polyamide P1 in granular form.

[0170] • Membrane fabrication (simultaneous biaxial stretching of the membrane)

[0171] 100 parts by weight of the obtained granules were dry-mixed with 0.4 parts by weight of Sumilizer GA-80, and fed into a twin-screw extruder with a screw diameter of 26 mm and a cylinder temperature of 330°C for melt mixing and extrusion into strips. Subsequently, the strips were cooled and cut to obtain granules.

[0172] The obtained granules were fed into a uniaxial extruder with a screw diameter of 50 mm, heated to a cylinder temperature of 330°C, for melting to obtain a molten polymer. This molten polymer was then filtered using a metal fiber sintered filter (manufactured by Nippon Seiki Co., Ltd., "NF-13", nominal filter diameter: 60 μm). Subsequently, the molten polymer was extruded into a film shape through a T-die set to 330°C, producing a film-like melt. This melt was then cooled and sealed on a cooling roller set to 0°C using an electrostatic application method to obtain a substantially unoriented, unstretched polyamide film.

[0173] The resin composition of the polyamide component of the obtained unstretched film was determined, and the result was that it was the same as the resin composition of the polyamide used.

[0174] The two ends of the unstretched polyamide film are held by clamps and biaxially stretched using a planar simultaneous biaxial stretching machine. The stretching conditions are: preheating temperature 80°C, stretching temperature 80°C, tensile strain rate of MD 2400% / min, tensile strain rate of TD 2400% / min, stretch ratio of MD 2.3 times, and stretch ratio of TD 2.3 times. After stretching, the film is continuously heat-fixed at 250°C in the same tenter frame of the biaxial stretching machine, and a 6% relaxation treatment is performed in the width direction to obtain the biaxially stretched polyamide film.

[0175] The resin composition of the polyamide component of the obtained stretched film is determined, and the result is the same as the resin composition of the polyamide used or the resin composition of the polyamide component of the unstretched film.

[0176] Examples 2-5

[0177] Except for changing the amount of monomer added to the reaction vessel as shown in Table 1, the same operation as in Example 1 was performed to obtain polyamides P2 to P5. Furthermore, using the obtained particles, the same operation as in Example 1 was performed, including melt mixing, unstretched film preparation, and simultaneous biaxial stretching, to obtain a simultaneously biaxially stretched film.

[0178] In the polyamide manufacturing process, the amount of reaction product added to the reaction vessel is equal to the total amount of terephthalic acid and decanediamine used in the reaction product manufacturing process.

[0179] Example 6

[0180] • Preparation of reaction products

[0181] In a belt mixer-type reaction apparatus, 26.8 parts by mass of terephthalic acid and 0.1 parts by mass of sodium hypophosphite monohydrate were added. Under nitrogen-sealed conditions, the mixture was stirred at 30 rpm and heated to 170°C. Then, maintaining the temperature at 170°C and the stirring speed at 30 rpm, 23.4 parts by mass of 1,10-decanediamine heated to 100°C was continuously added over 2.5 hours (continuous injection method) to obtain the reaction product. The molar ratio of the raw material monomers was terephthalic acid: 1,10-decanediamine = 54.3:45.7.

[0182] Production of polyamide

[0183] 18.6 parts by mass of dimer acid and 31.1 parts by mass of dimeric diamine were added to a reaction vessel equipped with a heating and stirring mechanism. After stirring at 100°C for 1 hour, 50.2 parts by mass of the above reaction product were added while stirring.

[0184] Subsequently, the mixture was heated to 260°C while stirring, and the condensation water was removed from the system. Polymerization was then carried out for 5 hours at atmospheric pressure and 260°C under a nitrogen stream. During the polymerization process, the system remained in a suspension state.

[0185] After polymerization, the material is discharged, cut, and dried to obtain polyamide P6.

[0186] Simultaneous fabrication of biaxial stretch film

[0187] Using the obtained particles, the same operation as in Example 1 was performed: melt mixing, unstretched film preparation, and simultaneous biaxial stretching to obtain a simultaneously biaxially stretched film.

[0188] Examples 7-9

[0189] Except for changing the amount of monomer added to the reaction vessel as shown in Table 1, the same operation as in Example 6 was performed to obtain polyamides P7 to P9. Furthermore, using the obtained particles, the same operation as in Example 1 was performed, including melt mixing, unstretched film preparation, and simultaneous biaxial stretching, to obtain a simultaneously biaxially stretched film.

[0190] In the polyamide manufacturing process, the amount of reaction product added to the reaction vessel is equal to the total amount of terephthalic acid and decanediamine used in the reaction product manufacturing process.

[0191] Example 10

[0192] • Preparation of reaction products

[0193] In a belt mixer-type reaction apparatus, 29.7 parts by mass of terephthalic acid and 0.1 parts by mass of sodium hypophosphite monohydrate were added. Under nitrogen-sealed conditions, the mixture was stirred at 30 rpm and heated to 170°C. Then, maintaining the temperature at 170°C and the stirring speed at 30 rpm, 20.8 parts by mass of 1,6-hexanediamine heated to 100°C was continuously added over 2.5 hours (continuous injection method) to obtain the reaction product. The molar ratio of the raw material monomers was terephthalic acid: 1,6-hexanediamine = 50.0:50.0.

[0194] Production of polyamide

[0195] 25.4 parts by mass of dimer acid and 24.0 parts by mass of dimeric diamine were added to a reaction vessel equipped with a heating and stirring mechanism. After stirring at 100°C for 1 hour, 50.5 parts by mass of the above reaction product were added while stirring.

[0196] Subsequently, the mixture was heated to 260°C while stirring, and the condensation water was removed from the system. Polymerization was then carried out for 5 hours at atmospheric pressure and 260°C under a nitrogen stream. During the polymerization process, the system remained in a suspension state.

[0197] After polymerization, the material is discharged, cut, and dried to obtain polyamide P10 in granular form.

[0198] Simultaneous fabrication of biaxial stretch film

[0199] Using the obtained particles, the same operation as in Example 1 was performed: melt mixing, unstretched film preparation, and simultaneous biaxial stretching to obtain a simultaneously biaxially stretched film.

[0200] Examples 11, 16, and 19

[0201] • Fabrication of unstretched membrane

[0202] In Examples 11, 16, and 19, the substantially unoriented, unstretched polyamide films obtained in Examples 1, 3, and 4 were heat-treated at 250°C.

[0203] Examples 12-14

[0204] Simultaneous fabrication of biaxial stretch film

[0205] Using the substantially unoriented, unstretched polyamide film obtained in Example 1, the manufacturing conditions were changed as shown in Table 3, and the same operations as in Example 1 were performed to obtain a biaxially stretched polyamide film.

[0206] Examples 17 and 18

[0207] Simultaneous fabrication of biaxial stretch film

[0208] Using the substantially unoriented, unstretched polyamide film obtained in Example 3, the manufacturing conditions were changed as shown in Table 3, and the same operation as in Example 1 was performed to obtain a biaxially stretched polyamide film.

[0209] Examples 20 and 21

[0210] Simultaneous fabrication of biaxial stretch film

[0211] Using the substantially unoriented, unstretched polyamide film obtained in Example 4, the manufacturing conditions were changed as shown in Table 3, and the same operation as in Example 1 was performed to obtain a biaxially stretched polyamide film.

[0212] Example 15 (Successive Biaxial Stretching Membrane)

[0213] The substantially unoriented, unstretched polyamide film obtained in Example 1 was biaxially stretched using a planar successive biaxial stretching machine. First, the unstretched film was heated to 80°C using roller heating or infrared heating, and then stretched 3.0 times on a MD (dimension tensile) machine at a tensile strain rate of 2400% / min to obtain a longitudinally stretched film. Next, the film was continuously stretched transversely by holding both ends in the width direction using the clamps of a transverse stretching machine. The preheating temperature of the TD (dimension tensile) stretching section was 85°C, the stretching section temperature was 85°C, the tensile strain rate was 2400% / min, and the TD stretching ratio was 3.0 times. Then, it was heat-fixed at 250°C in the same tenter frame of the transverse stretching machine, and a 6% relaxation treatment was performed in the width direction of the film to obtain a biaxially stretched polyamide film.

[0214] Comparative Example 1

[0215] In a reaction vessel equipped with a heating mechanism and a stirring mechanism, 26.7 parts by mass of dimer acid, 25.3 parts by mass of dimeramine, 23.5 parts by mass of terephthalic acid, 24.4 parts by mass of 1,10-decanediamine, and 0.1 parts by mass of sodium hypophosphite monohydrate are added.

[0216] Subsequently, the mixture was heated to 260°C while stirring, and the condensation water was removed from the system. Polymerization was then carried out for 5 hours at atmospheric pressure and 260°C under a nitrogen flow. The system remained in suspension during the polymerization process.

[0217] After polymerization, the material is discharged, cut, and dried to obtain polyamide P11 in granular form.

[0218] In addition, the obtained particles were used to perform the same operation as in Example 1, including melt mixing, unstretched film preparation, and simultaneous biaxial stretching, to obtain a simultaneously biaxially stretched film.

[0219] Comparative Examples 2-5

[0220] The amounts of dimer acid, dimeramine, terephthalic acid, and 1,10-decanediamine were changed to those in Table 1. Otherwise, the same operation as in Comparative Example 1 was performed to obtain polyamides P12 to P15.

[0221] In addition, the obtained particles were used to perform the same operation as in Example 1, including melt mixing, unstretched film preparation, and simultaneous biaxial stretching, to obtain a simultaneously biaxially stretched film.

[0222] Comparative Example 6

[0223] In a powder stirring apparatus equipped with a heating mechanism, 49.0 parts by mass of terephthalic acid and 0.1 parts by mass of sodium hypophosphite monohydrate were added. While heating at 170°C, 50.9 parts by mass of 1,10-decanediamine were added gradually in small amounts over 3 hours with stirring to obtain the reaction product. Subsequently, the reaction product was heated to 250°C with stirring, and while removing the condensation water from the system, polymerization was carried out under a nitrogen stream at atmospheric pressure and 250°C for 7 hours. During the polymerization process, the system remained in a powder state.

[0224] After polymerization, the product is discharged to obtain polyamide P16 in powder form.

[0225] In addition, using the obtained powder, the same operation as in Example 1 was performed, including melt mixing, preparation of an unstretched film, and simultaneous biaxial stretching, to obtain a simultaneously biaxially stretched film.

[0226] Comparative Example 7

[0227] In a reaction vessel equipped with a heating mechanism and a stirring mechanism, 51.3 parts by mass of dimer acid, 48.6 parts by mass of dimeric diamine, and 0.1 parts by mass of sodium hypophosphite monohydrate are added.

[0228] Subsequently, the mixture was heated to 260°C with stirring to remove the condensation water from the system. Polymerization was then carried out for 5 hours at atmospheric pressure and 260°C under a nitrogen atmosphere. During the polymerization process, the system remained in a homogeneous molten state.

[0229] After polymerization, the material is discharged, cut, and dried to obtain polyamide P17 in granular form.

[0230] In addition, using the obtained particles, the same operation as in Example 1 was performed, including melt mixing, production of an unstretched film, and biaxial stretching, but a stretched film could not be obtained.

[0231] Comparative Example 8

[0232] In a reaction vessel equipped with a heating mechanism and a stirring mechanism, 51.0 parts by weight of polyoxytetramethylene glycol (PTMG1000) with a number average molecular weight of 1000 (replacing the hydroxyl groups at both ends with amino groups), 28.3 parts by weight of terephthalic acid, 20.6 parts by weight of 1,10-decanediamine, and 0.1 parts by weight of sodium hypophosphite monohydrate were added.

[0233] Subsequently, the mixture was heated to 250°C while stirring, and the condensation water was removed from the system. Polymerization was then carried out for 5 hours at atmospheric pressure and 250°C under a nitrogen stream. During the polymerization process, the system remained in a suspension state.

[0234] After polymerization, the material is discharged, cut, and dried to obtain polyamide P18 in granular form, but it is fragile and unsuitable for practical use.

[0235] Comparative Examples 9, 11, and 13

[0236] • Fabrication of unstretched membrane

[0237] In Comparative Examples 9, 11, and 13, the substantially unoriented, unstretched polyamide films obtained in Comparative Examples 1, 3, and 4 were heat-treated at 200°C.

[0238] Comparative Examples 10, 12, and 14

[0239] In Comparative Examples 10, 12, and 14, the substantially unoriented, unstretched polyamide films obtained in Comparative Examples 1, 3, and 4 were used, and the manufacturing conditions were changed as shown in Table 3. Otherwise, the same operation as in Example 1 was performed to obtain biaxially stretched polyamide films.

[0240] Table 1 shows the feed composition, molar ratio of component (C) to (D), and polymerization method of the polyamides obtained in Examples 1-10 and Comparative Examples 1-8.

[0241]

[0242] The abbreviations in Table 1 are shown below.

[0243] A = Aliphatic dicarboxylic acid (A) with 18 or more carbon atoms (dimeric acid)

[0244] C = Aromatic dicarboxylic acids with 12 or fewer carbon atoms (C) (terephthalic acid)

[0245] B = aliphatic diamines with 18 or more carbon atoms (B) (dimeric diamine)

[0246] D1 = Aliphatic diamines (D)(decanediamine) with 12 or fewer carbon atoms

[0247] D2 = aliphatic diamines (D)(1,6-hexanediamine) with 12 or fewer carbon atoms.

[0248] E = PTMG1000 with amino groups at both ends

[0249] F = sodium hypophosphite monohydrate

[0250] The final composition of the polyamides obtained in Examples 1-10 and Comparative Examples 1-8, and the evaluation of the obtained polyamides and biaxially stretched films are shown in Table 2.

[0251]

[0252] The abbreviations in Table 2 are shown below.

[0253] A to C, D1, D2 and E are the same as A to C, D1, D2 and E in Table 1, respectively.

[0254] (1) Reduction rate of Shore D hardness (%);

[0255] (2) Increase rate of elongation recovery (%);

[0256] (3) Reduction rate of lag loss rate (%).

[0257] In Table 2, the values ​​of (1) to (3) above are shown only in Examples 1 to 5 because there are Comparative Examples 1 to 5 with the same monomer composition as Examples 1 to 5. It is meaningful to compare the values ​​in Examples and Comparative Examples with the same monomer composition with each other.

[0258] The reduction rate (%) of Shore D hardness in Examples 1 to 5 are the proportions of the amount of Shore D hardness reduced from that in Comparative Examples 1 to 5.

[0259] The reduction rate of Shore D hardness is typically 2% or more (△: practically problem-free range), preferably 5% or more (○: good), and more preferably 6.5% or more (◎: excellent).

[0260] The increase rate (%) of elongation recovery rate in Examples 1 to 5 is the proportion of the increase in elongation recovery rate from Comparative Examples 1 to 5.

[0261] The increase in elongation recovery rate is typically 10% or more (△: a range that is practically problem-free), preferably 20% or more (○: good), and more preferably 40% or more (◎: excellent).

[0262] The reduction rate (%) of hysteresis loss rate in Examples 1 to 5 is the proportion of the reduction in hysteresis loss rate from Comparative Examples 1 to 5.

[0263] The reduction rate of hysteresis loss rate is typically 2% or more (△: a range that is practically problem-free), preferably 4% or more (○: good), and more preferably 5.5% or more (◎: excellent).

[0264] In Examples 1 to 5, the melting point is generally above 240°C (△: a range that is practically without problems), preferably above 270°C (○: good), and more preferably above 300°C (◎: excellent).

[0265] In Examples 1-5, the more evaluation items marked with ◎, the better.

[0266] The evaluations of the unstretched films obtained in Examples 11, 16, and 19 and the evaluations of the biaxially stretched films obtained in Examples 12–15, 17, 18, 20, and 21 are shown in Table 3.

[0267]

[0268] The evaluation of the thermal shrinkage rate and dielectric properties (relative permittivity, dielectric loss tangent) at 200°C for Examples 11, 1, 3, 4 and Comparative Examples 9, 1, 3, 4, 6 is shown in Table 4.

[0269]

[0270] The polyamides in Examples 1-10 meet the requirements specified in this invention, exhibiting excellent heat resistance and flexibility, with melting points of 240°C or higher for all heat resistance indicators and elongation recovery rates of 50% or higher for hysteresis tests, which are indicators of flexibility. Furthermore, the polyamides in Examples 1-10 have crystal melting enthalpies of 20 J / g or higher for the crystallinity indicators of hard segments, allowing the hard segments to fully utilize their crosslinking points, resulting in excellent rubber elasticity. The resulting stretched films also exhibit excellent flexibility.

[0271] By comparing the polyamides of Examples 1-5 with those of Comparative Examples 1-5, it can be seen that the polyamides obtained by the two-step method of adding the reaction product of the hard segment to the reaction product of the soft segment for polymerization have a larger elongation recovery rate and crystal melting enthalpy, and smaller Shore D hardness and hysteresis loss rate, as well as improved softness and rubber elasticity, compared with the polyamides obtained by the conventional single-step method of adding raw materials together for polymerization. For the resulting stretch film, the elongation is also increased, and the elastic modulus is decreased.

[0272] The polyamides in Comparative Examples 1, 3-5 had low elongation recovery and low softness.

[0273] The polyamide in Comparative Example 2 has a lower enthalpy of fusion and lower crystallinity of hard segments.

[0274] The polyamide in Comparative Example 6 has low elongation recovery and low flexibility because it does not contain components (A) and (B) that form soft segments.

[0275] The polyamide of Comparative Example 7 has a low melting point and low heat resistance because it does not contain components (C) and (D) that form hard segments.

[0276] Industrial availability

[0277] The polyamide and film of the present invention possess excellent properties such as heat resistance, softness, and rubber elasticity, and are therefore useful in various applications such as packaging materials where these properties are required.

Claims

1. A polyamide comprising units formed of aliphatic dicarboxylic acids A having 18 or more carbon atoms, units formed of aliphatic diamines B having 18 or more carbon atoms, units formed of aromatic dicarboxylic acids C having 12 or fewer carbon atoms, and units formed of aliphatic diamines D having 12 or fewer carbon atoms, and having a melting point of 240°C or higher, a crystal melting enthalpy of 20 J / g or higher, and an elongation recovery rate of 50% or higher in a hysteresis test. The content of the unit formed by the aliphatic dicarboxylic acid A with 18 or more carbon atoms is 3 to 45% by mass relative to the total monomer composition of the polyamide. The content of the unit formed by the aliphatic diamine B with 18 or more carbon atoms is 3 to 45% by mass relative to the total monomer composition of the polyamide. The content of the unit formed from an aromatic dicarboxylic acid C with 12 or fewer carbon atoms is 3-45% by mass relative to the total monomer composition of the polyamide. The content of the unit formed by the aliphatic diamine D with 12 or fewer carbon atoms is 3 to 52% by mass relative to the total monomer content constituting the polyamide.

2. The polyamide according to claim 1, wherein, The aliphatic dicarboxylic acid A with 18 or more carbon atoms is a dimer acid.

3. The polyamide according to claim 1 or 2, wherein, The aliphatic diamine B with 18 or more carbon atoms is a dimeric diamine.

4. The polyamide according to claim 1 or 2, wherein, The aromatic dicarboxylic acid C with 12 or fewer carbon atoms is terephthalic acid.

5. The polyamide according to claim 1 or 2, wherein, The aliphatic diamine D with 12 or fewer carbon atoms is 1,10-decanediamine.

6. The polyamide according to claim 1 or 2, wherein, The total content of the unit formed by aliphatic dicarboxylic acid A with 18 or more carbon atoms and the unit formed by aliphatic diamine B with 18 or more carbon atoms is 10 to 90% by mass relative to the total monomer composition of the polyamide.

7. The polyamide according to claim 1 or 2, wherein, The total content of the unit formed by aliphatic dicarboxylic acid A with 18 or more carbon atoms and the unit formed by aliphatic diamine B with 18 or more carbon atoms is 20 to 80% by mass relative to the total monomer composition of the polyamide.

8. The polyamide according to claim 1 or 2, wherein, The aliphatic dicarboxylic acid A with 18 or more carbon atoms has 30 to 40 carbon atoms. The aliphatic diamine B with 18 or more carbon atoms has 30 to 40 carbon atoms. The aromatic dicarboxylic acids with 12 or fewer carbon atoms have a carbon number of 6 to 12. The aliphatic diamine D with 12 or fewer carbon atoms has 6 to 12 carbon atoms.

9. A molded article comprising the polyamide according to any one of claims 1 to 8.

10. A membrane comprising the polyamide according to any one of claims 1 to 8.

11. A method for manufacturing a polyamide, comprising reacting the following components to polymerize: Aliphatic dicarboxylic acids A with 18 or more carbon atoms Aliphatic diamines B with 18 or more carbon atoms The reaction products of aromatic dicarboxylic acids (C) with 12 or fewer carbon atoms and aliphatic diamines (D) with 12 or fewer carbon atoms. In the polyamide, The content of the unit formed by the aliphatic dicarboxylic acid A with 18 or more carbon atoms is 3 to 45% by mass relative to the total monomer composition of the polyamide. The content of the unit formed by the aliphatic diamine B with 18 or more carbon atoms is 3 to 45% by mass relative to the total monomer composition of the polyamide. The content of the unit formed from an aromatic dicarboxylic acid C with 12 or fewer carbon atoms is 3-45% by mass relative to the total monomer composition of the polyamide. The content of the unit formed by the aliphatic diamine D with 12 or fewer carbon atoms is 3 to 52% by mass relative to the total monomer content constituting the polyamide.

12. A method for manufacturing a polyamide, comprising pre-reacting an aliphatic dicarboxylic acid A with 18 or more carbon atoms with an aliphatic diamine B with 18 or more carbon atoms, and then reacting the product of the reaction of an aromatic dicarboxylic acid C with 12 or fewer carbon atoms with an aliphatic diamine D with 12 or fewer carbon atoms to polymerize the polyamide. In the polyamide, The content of the unit formed by the aliphatic dicarboxylic acid A with 18 or more carbon atoms is 3 to 45% by mass relative to the total monomer composition of the polyamide. The content of the unit formed by the aliphatic diamine B with 18 or more carbon atoms is 3 to 45% by mass relative to the total monomer composition of the polyamide. The content of the unit formed from an aromatic dicarboxylic acid C with 12 or fewer carbon atoms is 3-45% by mass relative to the total monomer composition of the polyamide. The content of the unit formed by the aliphatic diamine D with 12 or fewer carbon atoms is 3 to 52% by mass relative to the total monomer content constituting the polyamide.

13. The method for manufacturing polyamide according to claim 11 or 12, wherein the polyamide according to any one of claims 1 to 8 is manufactured.

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