JP2007092053A - Polyamide and composition containing the polyamide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyamide having satisfactory thermal stability during drying or molding, being free from discoloration, even when a recycled article of the polymer is mixed and used being reduced in the generation of gel particles or other undesirable substances, and exhibiting excellent productivity in molding and to provide a composition containing the polyamide. <P>SOLUTION: The polyamide which is either a polyamide comprising, as a main structural unit, a unit derived from an aliphatic dicarboxylic acid and an aromatic diamine, or a polyamide comprising, as a main structural unit, a unit derived from an aromatic dicarboxylic acid and an aliphatic diamine, is characterized in that, when the polyamide is dissolved in a solvent used in the<SP>31</SP>P-NMR spectroscopy measurement and the resultant solution is subjected to structure analysis after trifluoroacetic acid is added thereto, then the content of a phosphorus atom (P1) derived from a phosphorus compound of a structure detected with the structural formula (1) is 10 ppm or higher. In the structural formula (1), R<SB>1</SB>and R<SB>2</SB>are each hydrogen, an alkyl group, an aryl group, a cycloalkyl group, or an aryl alkyl group, and X<SB>1</SB>is hydrogen. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a polyamide suitably used as a material for a molded body such as a film or a sheet, a hollow molded container such as a beverage bottle, an engineering plastics material, and a polyamide composition comprising the polyamide. In addition, they have good thermal stability when they are dried or molded, and the color tone does not deteriorate even when recycled products are used. The present invention relates to an excellent polyamide and a polyamide composition comprising the same.

  Polyamides are widely used in applications such as hollow molded containers, films, sheet packaging materials, engineering plastics and fibers because of their excellent physical and mechanical properties. Typical examples include aliphatic polyamides such as nylon 6 and nylon 66. Besides these, aromatic diamines such as paraxylylenediamine (PXDA) and metaxylylenediamine (MXDA), and aromatic dicarboxylic acids such as terephthalic acid. Many polyamides that use an acid as a raw material to achieve reduced water absorption and improved elastic modulus are also known.

  Polyamide is relatively unstable to heat than polyester or the like, and may cause gelation or yellowing due to thermal degradation or thermal oxidation degradation.

  As a method for suppressing the thermal deterioration of polyamide, a method of adding a phosphonic acid compound or a phosphorous acid compound and an alkali metal to the polyamide has been proposed (for example, see Patent Document 1).

  Further, as a method for suppressing thermal degradation of polyamide, (a) phosphinic acid compound, phosphonous acid compound, phosphonic acid compound or phosphorous acid compound, (b) alkali metal, (c) phenylenediamine and / or A method of blending a derivative has been proposed (for example, see Patent Document 2).

  Methods for preventing thermal degradation in systems below the melting point of polyamide and without oxygen include pyrophosphites, amide compounds of organic phosphinic acids, barium salts of phosphorous acid mono- or diesters, mono- or diesters of orthophosphoric acid A method of adding a copper salt or the like has been proposed (see, for example, Patent Documents 3, 4, 5, and 6).

  In addition, 0.0005 to at least one selected from a lubricant, an organophosphorus stabilizer, a hindered phenol compound, and a hindered amine compound as a measure for preventing the formation of a gelled polyamide comprising metaxylylenediamine and adipic acid It is being studied by adding 0.5 part by weight (see, for example, Patent Document 7).

  In addition, a method of polymerizing a polyamide mainly composed of terephthalic acid and hexamethylenediamine in the presence of hypophosphite (see, for example, Patent Document 8), adipic acid, terephthalic acid, isophthalic acid and hexamethylenediamine are hypochlorous A method of polymerizing in the presence of a phosphate (see, for example, Patent Document 9) is disclosed.

Although these techniques are effective in preventing gelation of polyamide, they are not satisfactory, and depending on molding conditions such as drying conditions, molding temperature, and melting time, coloring and gelation may occur. Generation of the resulting foreign matter, abnormal appearance of the molded product, or deterioration of transparency occurs, and a solution is desired.
JP 49-45960 A JP-A-49-53945 Japanese Examined Patent Publication No. 45-11836 Japanese Patent Publication No. 45-35667 Japanese Patent Publication No. 45-12986 Japanese Patent Publication No.46-38351 JP 2001-164109 A JP-A-5-43681 Japanese Patent Laid-Open No. 3-126725

  The present invention solves the above-mentioned problems of the prior art, has good thermal stability during drying and molding, and does not deteriorate color tone when used as a recycled product. An object of the present invention is to provide a polyamide having a low production rate and excellent productivity during molding and a polyamide composition comprising the same.

The inventors of the present invention have arrived at the present invention as a result of intensive studies to achieve the above object. That is, the polyamide of the present invention is a polyamide having a unit derived from an aliphatic dicarboxylic acid and an aromatic diamine as a main structural unit, or a unit derived from an aromatic dicarboxylic acid and an aliphatic diamine as a main structural unit. A polyamide that is dissolved in a ³¹ P-NMR measurement solvent, added with trifluoroacetic acid, and structurally analyzed, and contains a phosphorus compound that is detected by the structure of the following structural formula (formula 1), and A polyamide having a phosphorus atom content (P1) derived from a phosphorus compound of 10 ppm or more.

(Where R ₁ and R ₂ are hydrogen, alkyl group, aryl group, cycloalkyl group or arylalkyl group, and X ₁ is hydrogen)

In this case, when the polyamide is dissolved in ³¹ P-NMR measurement solvent and trifluoroacetic acid is added and then structural analysis is performed, the polyamide contains a phosphorus compound detected by the structure of the following structural formula (formula 2). And the phosphorus atom content (P2) derived from the phosphorus compound represented by the structural formula (Formula 2) can be 30 ppm or more.

(Wherein R ₃ is hydrogen, an alkyl group, an aryl group, a cycloalkyl group or an arylalkyl group, X ₂ and X ₃ are hydrogen)
Here, for the measurement of the content of the phosphorus compound of the above structural formula in the polyamide, the structural analysis ³¹ P-NMR method of the phosphorus compound described later was used. P1 and P2 are contents relative to the weight of the polyamide.

  Moreover, the polyamide can contain 50 mol% or more of structural units derived from metaxylylenediamine and dicarboxylic acid in the molecular chain.

Further, the polyamide can contain 50 mol% or more of structural units derived from metaxylylenediamine and adipic acid in the molecular chain.

Further, the color b value (Co-b) of the polyamide chip can satisfy the following formula (1).

      −5 <(Co−b) <10 (1)

  Furthermore, a polyamide composition containing any of the polyamides and aliphatic polyamides as main components can be formed.

  Since the polyamide of the present invention has good thermal stability and thermal oxidation stability at the time of drying and molding, it has excellent color tone and is difficult to be colored in the molding process, and the generation of foreign matters such as gel-like substances occurs. Therefore, it can be suitably used as a material for molded articles such as films and sheets, hollow molded containers such as beverage bottles, engineering plastics materials, etc., and these molded articles can be produced with high productivity. . Moreover, it can use as molded objects, such as a film and a sheet, as a composition with aliphatic polyamide.

Hereinafter, embodiments of the polyamide of the present invention and a polyamide composition comprising the same will be specifically described.
The polyamide of the present invention is a polyamide whose main constituent unit is a unit derived from an aliphatic dicarboxylic acid and an aromatic diamine, or a polyamide whose main constituent unit is a unit derived from an aromatic dicarboxylic acid and an aliphatic diamine. In the case where the polyamide is dissolved in a ³¹ P-NMR measurement solvent and trifluoroacetic acid is added and the structure is analyzed, the phosphorus atom content (P1) derived from the phosphorus compound detected by the structure of the following structural formula (formula 1) ) Is 10 ppm or more.

(Where R ₁ and R ₂ are hydrogen, alkyl group, aryl group, cycloalkyl group or arylalkyl group, and X ₁ is hydrogen)

When the polyamide is dissolved in a ³¹ P-NMR measurement solvent and subjected to structural analysis after adding trifluoroacetic acid, the phosphorus atom content (P1) derived from the phosphorus compound detected by the structure of the structural formula (Formula 1) is more preferable. Is 15 ppm or more, more preferably 20 ppm or more. When the P1 content is less than 10 ppm, the polyamide has poor thermal stability, so that only a molded product that is intensely colored yellow when heated in the presence of oxygen, such as hot air drying, or melt molding, can be obtained. In addition, a gel-like material is easily generated, and foreign matter, fish eyes, and the like are generated in a molded body such as a film. In particular, when oxygen is present in the molding atmosphere, the quality deterioration of the molded body as described above becomes significant.
As an upper limit of P1, 350 ppm or less is preferable, More preferably, it is 320 ppm or less, More preferably, it is 300 ppm or less. When the content of P1 exceeds 350 ppm, it is possible to increase the molecular weight in the subsequent process and to precipitate as foreign matters with these as a starting point, which is not preferable because it causes filter clogging.

When the polyamide of the present invention is dissolved in a ³¹ P-NMR measurement solvent and subjected to structural analysis after adding trifluoroacetic acid, the phosphorus atom content (P2) derived from the phosphorus compound detected by the structure of the following structural formula (formula 2) ) Is preferably 30 ppm or more.

(Wherein R ₃ is hydrogen, an alkyl group, an aryl group, a cycloalkyl group or an arylalkyl group, X ₂ and X ₃ are hydrogen)

When the polyamide is dissolved in a ³¹ P-NMR measurement solvent and structural analysis is performed after adding trifluoroacetic acid, the phosphorus atom content (P2) derived from the phosphorus compound detected by the structure of the structural formula (Formula 2) is more preferable. Is 35 ppm or more, more preferably 40 ppm or more. The phosphorus atom content (P1) derived from the phosphorus compound detected in the structure of the structural formula (formula 1) in the polyamide is 10 ppm or more, and derived from the phosphorus compound detected in the structure of the structural formula (formula 2) When the content of the phosphorus atom content (P2) is 30 ppm or more than when the phosphorus atom content (P1) derived from the phosphorus compound detected in the structure of the structural formula (Formula 1) only satisfies 10 ppm or more However, the thermal stability of the polyamide of the present invention is further improved.
As an upper limit of P2, 300 ppm or less is preferable, More preferably, it is 270 ppm or less, More preferably, it is 250 ppm or less. When the content of P2 exceeds 300 ppm, it is possible to increase the molecular weight in the subsequent process and to precipitate as a foreign substance with these as a starting point, which is not preferable because it causes filter clogging.

  The polyamide of the present invention is a polyamide whose main constituent unit is a unit derived from an aliphatic dicarboxylic acid and an aromatic diamine, or a polyamide whose main constituent unit is a unit derived from an aromatic dicarboxylic acid and an aliphatic diamine. A polyamide containing 50 mol% or more, preferably 60 mol% or more, particularly preferably 70 mol% or more in the molecular chain.

In the following, the polyamide of the present invention may be referred to as a partially aromatic polyamide.
When the polyamide of the present invention is a polyamide having a main constituent unit derived from an aliphatic dicarboxylic acid and an aromatic diamine, examples of the aromatic diamine component constituting such polyamide include metaxylylenediamine, paraxylylene. Examples include range amine and para-bis (2-aminoethyl) benzene.

  The aliphatic diamine component constituting such polyamide is an aliphatic diamine having 2 to 12 carbon atoms or a functional derivative thereof. The aliphatic diamine may be a linear aliphatic diamine or a branched chain aliphatic diamine. Specific examples of such linear aliphatic diamines include ethylenediamine, 1-methylethylenediamine, 1,3-propylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, Examples include aliphatic diamines such as nonamethylenediamine, decamethylenediamine, undecamethylenediamine, and dodecamethylenediamine.

  When the polyamide of the present invention is a polyamide having a main structural unit derived from an aromatic dicarboxylic acid and an aliphatic diamine, examples of the aromatic dicarboxylic acid component constituting the polyamide include terephthalic acid, isophthalic acid, Examples thereof include phthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyl-4,4′-dicarboxylic acid, diphenoxyethanedicarboxylic acid, and functional derivatives thereof.

  Moreover, as the aliphatic dicarboxylic acid component constituting such a polyamide, a linear aliphatic dicarboxylic acid is preferable, and a linear aliphatic dicarboxylic acid having an alkylene group having 4 to 12 carbon atoms is particularly preferable. Examples of such linear aliphatic dicarboxylic acids include adipic acid, sebacic acid, malonic acid, succinic acid, glutaric acid, pimelic acid, spellic acid, azelaic acid, undecanoic acid, undecanoic acid, dodecanedioic acid , Dimer acids and functional derivatives thereof.

  Moreover, alicyclic diamine can also be used as a diamine component which comprises the polyamide of this invention other than the above aromatic diamine and aliphatic diamine. Examples of the alicyclic diamine include alicyclic diamines such as cyclohexanediamine, 1,3-bis (aminomethyl) cyclohexane, and 1,4-bis (aminomethyl) cyclohexane.

  In addition to the aromatic dicarboxylic acid and the aliphatic dicarboxylic acid as described above, an alicyclic dicarboxylic acid can also be used as the dicarboxylic acid component constituting the polyamide of the present invention. Examples of the alicyclic dicarboxylic acid include alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, hexahydroterephthalic acid, and hexahydroisophthalic acid.

  In addition to the above diamines and dicarboxylic acids, lactams such as ε-caprolactam and laurolactam, aminocarboxylic acids such as aminocaproic acid and aminoundecanoic acid, aromatic aminocarboxylic acids such as para-aminomethylbenzoic acid, etc. It can be used as a polymerization component. In particular, the use of ε-caprolactam is desirable.

  Further, as a copolymerization component, a polyether having at least one terminal amino group or a terminal carboxyl group and a molecular weight of 2000 to 20000, or an organic carboxylate of the polyether having the terminal amino group, or the terminal carboxyl group It is also possible to use an amino salt of a polyether having the same. Specific examples include bis (aminopropyl) poly (ethylene oxide) (polyethylene glycol having a molecular weight of 2000 to 20000).

  Preferred examples of the partially aromatic polyamide of the present invention are derived from metaxylylenediamine or mixed xylylenediamine containing metaxylylenediamine and 30% or less of the total amount of paraxylylenediamine and an aliphatic dicarboxylic acid. It is a metaxylylene group-containing polyamide containing at least 50 mol% or more, more preferably 60 mol% or more, particularly preferably 70 mol% or more of the structural unit in the molecular chain.

  Further, the partially aromatic polyamide of the present invention may contain a structural unit derived from a polybasic carboxylic acid having 3 or more bases such as trimellitic acid and pyromellitic acid within a substantially linear range. Good.

  Examples of these polyamides include homopolymers such as polymetaxylylene adipamide, polymetaxylylene sebacamide, polymetaxylylene speramide, and metaxylylenediamine / adipic acid / isophthalic acid copolymers, metaxylylene. / Paraxylylene adipamide copolymer, metaxylylene / paraxylylene piperamide copolymer, metaxylylene / paraxylylene azelamide copolymer, metaxylylenediamine / adipic acid / isophthalic acid / ε-caprolactam copolymer And metaxylylenediamine / adipic acid / isophthalic acid / ω-aminocaproic acid copolymer.

  Further, as another preferred example of the partially aromatic polyamide of the present invention, a structural unit derived from an aliphatic diamine and at least one acid selected from terephthalic acid or isophthalic acid is at least 50 mol% in the molecular chain. More preferably, it is a polyamide containing 60 mol% or more, particularly preferably 70 mol% or more.

  Examples of these polyamides include polyhexamethylene terephthalamide, polyhexamethylene isophthalamide, hexamethylene diamine / terephthalic acid / isophthalic acid copolymer, polynonamethylene terephthalamide, polynonamethylene isophthalamide, nonamethylene diamine / terephthalic acid. / Isophthalic acid copolymer, nonamethylenediamine / terephthalic acid / adipic acid copolymer, and the like.

  Other preferred examples of the partially aromatic polyamide of the present invention include, in addition to at least one acid selected from aliphatic diamine and terephthalic acid or isophthalic acid, lactams such as ε-caprolactam and laurolactam, aminocaproic acid, At least one selected from aliphatic diamines and terephthalic acid or isophthalic acid obtained by using aminocarboxylic acids such as aminoundecanoic acid, aromatic aminocarboxylic acids such as para-aminomethylbenzoic acid and the like as copolymerization components A polyamide containing at least 50 mol%, more preferably 60 mol% or more, particularly preferably 70 mol% or more in the molecular chain of a structural unit derived from the above acid.

  Examples of these polyamides include hexamethylenediamine / terephthalic acid / ε-caprolactam copolymer, hexamethylenediamine / isophthalic acid / ε-caprolactam copolymer, hexamethylenediamine / terephthalic acid / adipic acid / ε-caprolactam copolymer Examples include coalescence.

  The polyamide of the present invention basically comprises a conventionally known melt polycondensation method in the presence of water or a melt polycondensation method in the absence of water, or a polyamide obtained by these melt polycondensation methods. It can be produced by a polymerization method or the like. The melt polycondensation reaction may be performed in one stage or may be performed in multiple stages. These may be comprised from a batch-type reaction apparatus, and may be comprised from the continuous-type reaction apparatus. The melt polycondensation step and the solid phase polymerization step may be operated continuously or may be operated separately.

  Hereinafter, a preferred batch-type production method of the polyamide of the present invention will be described using a xylylene group-containing polyamide (Ny-MXD6) as an example, but the present invention is not limited thereto.

  That is, for example, a salt of metaxylylenediamine and adipic acid, an alkali metal-containing compound containing an alkali metal atom as a thermal decomposition inhibitor, and an aqueous solution of a phosphorus compound are heated under pressure and normal pressure to produce water and a polycondensation reaction. It can be obtained by a method of polycondensation in a molten state while removing water generated in step (b).

  At this time, the tank for storing metaxylylenediamine and the tank for storing adipic acid are separately made into a nitrogen gas atmosphere, and the oxygen concentration in these nitrogen gas atmospheres is preferably 20 ppm or less. More preferably, it is 16 ppm, and most preferably 15 ppm. When the oxygen content in the nitrogen gas atmosphere in the storage tank exceeds 20 ppm, the phosphorus atom content (P1) derived from the phosphorus compound represented by the structural formula (formula 1) in the obtained polyamide is less than 10 ppm. Moreover, the phosphorus atom content (P2) derived from the phosphorus compound represented by the structural formula (Formula 2) is less than 30 ppm, and the thermal stability of the polyamide is inferior. Moreover, as a method of suppressing the oxygen concentration in the atmosphere in the storage tank, an inert gas such as nitrogen is allowed to flow into the tank, the air is replaced with nitrogen gas, and then an inert gas such as nitrogen gas is allowed to flow. Is preferable. Moreover, as a method of reducing the oxygen content in each raw material, it is preferable to bubble an inert gas from the bottom of the can. As the inert gas used, it is preferred to use nitrogen gas having an oxygen content of 12 ppm or less, more preferably 1 ppm or less.

  Further, in the step of mixing the raw materials, various additives, and water to prepare a salt of metaxylylenediamine and adipic acid, the oxygen concentration in the nitrogen gas atmosphere is 20 ppm or less, more preferably 18 ppm or less. It is preferably 16 ppm, and most preferably 15 ppm. Further, as a method of lowering the oxygen concentration, a method of bubbling by using an inert gas, for example, nitrogen gas, in the salt aqueous solution can be mentioned. Also in this step, when the oxygen content exceeds 20 ppm, the phosphorus atom content (P1) derived from the phosphorus compound represented by the structural formula (formula 1) in the obtained polyamide becomes less than 10 ppm, The phosphorus atom content (P2) derived from the phosphorus compound represented by the structural formula (Formula 2) is less than 30 ppm, and the thermal stability of the polyamide is inferior.

  The temperature at which the salt is prepared is preferably 140 ° C. or lower, more preferably 130 ° C. or lower in order to suppress coloring due to thermal oxidative degradation or to suppress side reactions or thermal oxidative degradation reactions of additives. More preferably, it is 120 ° C. or less, and most preferably 110 ° C. or less. Moreover, about a minimum, it is preferable to set it as the temperature which the solidification of the said salt does not occur, 30 degreeC or more, More preferably, it is 40 degreeC or more.

  Next, the prepared aqueous salt solution is transferred to a polymerization vessel and subjected to polycondensation. To evaporate water in the aqueous salt solution, in order to prevent scattering of unreacted substances and to prevent oxygen from being mixed into the system, While applying a pressure of 0.5 to 1.5 MPa in the can, the temperature was gradually raised, the distilled water was removed from the system, and the temperature in the can was 230 ° C. The reaction time at this time is preferably 1 to 7 hours, more preferably 2 to 6 hours, and further preferably 3 to 5 hours. An abrupt temperature rise is not preferable because it causes a high molecular weight of the additive and a side reaction of the polymer and causes a decrease in the thermal stability of the resin such as gelation in a subsequent process. Thereafter, the internal pressure of the can was gradually released over 30 to 90 minutes and returned to normal pressure. The temperature was further raised and the mixture was stirred at normal pressure to proceed the polymerization reaction. The polymerization temperature is preferably 280 ° C. or lower, more preferably 270 ° C. or lower, further preferably 265 ° C. or lower, and most preferably 260 ° C. or lower. When the polymerization temperature is higher than 280 ° C., it is not preferable because the additive has a high molecular weight and the thermal oxidation reaction or side reaction of the polymer further proceeds. The lower limit is preferably a temperature that does not solidify based on the polymer melting point. The polymerization time is preferably as short as possible, but is preferably within 2 hours, more preferably within 1.5 hours, and even more preferably within 1.0 hour.

  When the target viscosity was reached, stirring was stopped and allowed to stand to remove bubbles in the polymer. It is not preferable to leave it for a long time because it causes heat deterioration. The molten resin was taken out from the outlet at the bottom of the reaction can, cooled and solidified, and a resin chip was obtained with a chip cutter such as a strand cutter. In this case, if the time required for casting is long, it is not preferable because it is greatly affected by thermal oxidation deterioration at the take-out port, or the resin in the can etc. is thermally deteriorated and gelled products are formed or colored. . On the other hand, if the casting is too short, the temperature of the strand-shaped polymer coming out from the outlet becomes too high, so that the resin and additives are susceptible to thermal oxidative degradation, which may contribute to a decrease in the thermal stability of the polymer. Therefore, in the case of a batch reactor, the casting time is preferably 10 to 120 minutes, more preferably 15 to 100 minutes. Moreover, the strand polymer temperature in that case becomes like this. Preferably it is 20-70 degreeC, More preferably, it is the range of 30-65 degreeC. As another method, as a method for preventing thermal oxidative degradation of the polymer at the outlet, a method of spraying an inert gas can be mentioned.

  At this time, the phosphorus atom content (PC) and alkali metal atom content (M) derived from the phosphorus compound and alkali metal compound added at the time of producing the polyamide satisfy the ranges of the following formulas (2) and (3). preferable. In addition, since phosphorus compounds and alkali metals hardly scatter out of the system at the time of production, the following formulas (2) and (3) are used as the content in the obtained polyamide together with the addition amount during the production of polyamide. Is also a desirable range.

    50 ≦ PC <400ppm (2)

        1 <(M / PC) molar ratio <7 (3)

  With respect to the phosphorus atom content (PC), the lower limit is more preferably 60 ppm, and even more preferably 70 ppm or more. The upper limit is preferably 370 ppm, more preferably 350 ppm or less. Further, the lower limit of the M / PC molar ratio is more preferably 1.3, and still more preferably 1.5 or more. If the phosphorus atom content (PC) is less than 50 ppm, the color tone of the polymer deteriorates. It is inferior to thermal stability and is not preferred. Conversely, when the phosphorus atom content (PC) is 400 ppm or more, the raw material cost for the additive increases, which contributes to the cost increase or the filter foreign matter clogging at the time of melt molding increases. There is a concern about the decline in productivity. Further, when the (M / PC) molar ratio is 1 or less, there is a risk that the viscosity will increase sharply and the gelled product will be mixed more. On the other hand, when the (M / PC) ratio is 7 or more, the reaction rate is very slow and the productivity cannot be denied.

As a phosphorus compound which suppresses the thermal deterioration of polyamide, the compounds represented by the following chemical formulas (A-1) to (A-4) are exemplified.
As a phosphorus compound used at the time of manufacture of the polyamide of the present invention having good thermal stability and thermal oxidation stability during drying and molding, compounds represented by (A-1) and (A-3) are preferable. The compound represented by (A-1) is particularly preferable.

(In the formulas (A-1), (A-2), (A-3) and (A-4), R _{1 to} R ₇ are hydrogen, an alkyl group, an aryl group, a cycloalkyl group, or an arylalkyl group. , X _{1 to} X ₅ are hydrogen, alkyl group, aryl group, cycloalkyl group, arylalkyl group or alkali metal, alkaline earth metal, or each of X _{1 to} X ₅ and R _{1 to} R ₇ in each formula One may be linked together to form a ring structure)

  Examples of the phosphinic acid compound represented by the chemical formula (A-1) include dimethylphosphinic acid, phenylmethylphosphinic acid, hypophosphorous acid, sodium hypophosphite, potassium hypophosphite, lithium hypophosphite, hypochlorous acid. Magnesium phosphate, calcium hypophosphite, ethyl hypophosphite,

And hydrolysates thereof, and condensates of the above phosphonic acid compounds.
Among these, use of sodium hypophosphite, potassium hypophosphite, lithium hypophosphite, and magnesium hypophosphite is preferable.

  Examples of the phosphonic acid compound represented by the chemical formula (A-2) include phosphonic acid, sodium phosphonate, potassium phosphonate, lithium phosphonate, potassium phosphonate, magnesium phosphonate, calcium phosphonate, phenylphosphonic acid, ethylphosphonic acid, Examples include sodium phenylphosphonate, potassium phenylphosphonate, lithium phenylphosphonate, diethyl phenylphosphonate, sodium ethylphosphonate, and potassium ethylphosphonate.

  Examples of the phosphonous acid compound represented by the chemical formula (A-3) include phosphonous acid, sodium phosphonite, lithium phosphonite, potassium phosphonite, magnesium phosphonite, calcium phosphonite, and phenylphosphonous acid. , Sodium phenylphosphonite, potassium phenylphosphonite, lithium phenylphosphonite, ethyl phenylphosphonite, and the like.

  As the phosphite compound represented by the chemical formula (A-4), phosphorous acid, sodium hydrogen phosphite, sodium phosphite, lithium phosphite, potassium phosphite, magnesium phosphite, calcium phosphite, Examples include triethyl phosphite, triphenyl phosphite, pyrophosphorous acid and the like.

  In producing the polyamide of the present invention, an alkali metal-containing compound represented by the following chemical formula (B) is added.

Z-OR ₈ (B)

(However, Z is an alkali metal, _{R 8} is hydrogen, an alkyl group, an aryl group, a cycloalkyl group, -C (O) CH ₃ or -C (O) OZ ', ( Z' is hydrogen, an alkali metal))

  Examples of the alkali compound represented by the chemical formula (B) include lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, lithium acetate, sodium acetate, potassium acetate, rubidium acetate, cesium acetate, sodium methoxy And sodium ethoxide, sodium propoxide, sodium butoxide, potassium methoxide, lithium methoxide, sodium carbonate, etc., among which sodium hydroxide and sodium acetate are preferably used. However, any of them is not limited to these compounds.

  In order to mix the phosphorus compound or the alkali metal-containing compound with the polyamide of the present invention, the raw materials before polymerization of the polyamide, these may be added during the polymerization, or may be melt-mixed with the polymer. Moreover, these compounds may be added simultaneously or separately.

  The relative viscosity of the polyamide of the present invention is 1.5 to 4.0, preferably 1.5 to 3.0, more preferably 1.7 to 2.5, and still more preferably 1.8 to 2.0. It is. When the relative viscosity is 1.5 or less, the molecular weight is too small, and the molded article such as a film made of the polyamide of the present invention may be inferior in mechanical properties. On the other hand, if the relative viscosity is 4.0 or more, it takes a long time for the polymerization, which may cause deterioration of the polymer, gelation or undesired coloring, as well as decrease in productivity and increase in cost. Sometimes.

  In addition, the shape of the polyamide chip of the present invention may be any of a cylinder shape, a square shape, a spherical shape, a flat plate shape, and the like. The average particle size is usually in the range of 1.0 to 5 mm, preferably 1.2 to 4.5 mm, more preferably 1.5 to 4.0 mm. For example, in the case of a cylinder type, it is practical that the length is about 1.0 to 4 mm and the diameter is about 1.0 to 4 mm. In the case of spherical particles, it is practical that the maximum particle size is 1.1 to 2.0 times the average particle size and the minimum particle size is 0.7 times or more the average particle size. The weight of the chip is practically in the range of 3-50 mg / piece.

  Further, it is desirable that the color b value (Co-b) of the polyamide chip of the present invention satisfies the following formula (1).

    −5 <(Co−b) <10 (1)

  When the color b value (Co-b) is 10 or more, the hue of a molded article such as a bottle, a film, or a sheet becomes too yellow and the commercial value is lowered.

  The polyamide of the present invention can be molded into a desired final molded body by various molding techniques such as injection molding, extrusion molding, and blow molding. Examples of the molded article include a sheet (single layer, multilayer), a stretched film (single layer, multilayer), a packaging material such as a hollow molded article, an automobile part, a machine equipment part, and a laminate with paper.

  The polyamide of the present invention includes a lubricant, an antistatic agent, an antioxidant, an oxygen absorbent, an oxygen scavenger, an oxidation catalyst such as a cobalt compound, an antiblocking agent, a stabilizer, and the like within a range not impairing the object of the present invention. Various additives such as dyes, pigments, glass fibers, carbon fibers, calcium carbonate, mica, potassium titanate and other fibers or fillers can be added. In addition, modified polyolefin, ionomer resin, elastomer and the like can be added in order to improve mechanical properties, particularly bending properties, bending resistance, and the like.

  Furthermore, when using the polyamide of the present invention as engineering plastics for molded products for heat resistance, etc., weather resistance improving materials such as carbon black, copper oxide, alkali metal halides, hindered phenols, Heat stabilizers such as thioethers and phosphites, light stabilizers such as benzophenones, benzotriazoles, cyanoacrylates and hindered phenols, higher fatty acid salts, higher fatty acids, higher fatty acid esters, low molecular weight polyolefins, etc. Release agents, fluidity improvers such as lower aliphatic carboxylic acids and aromatic carboxylic acids, antistatic agents, crystal nucleating agents, lubricants, pigments, dyes, and the like may be included.

  Further, when the polyamide of the present invention is used for a film application, in order to improve handling properties such as slipperiness, rollability, and blocking resistance, silicon oxide, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, Inactive particles such as inorganic particles such as barium sulfate, lithium phosphate, calcium phosphate, and magnesium phosphate, and calcium oxalate may be included.

  The polyamide composition of the present invention is a polyamide composition containing the partially aromatic polyamide of the present invention and an aliphatic polyamide as main components. The blending ratio of the partially aromatic polyamide and the aliphatic polyamide in the polyamide composition of the present invention is 100/1 to 1/100 (weight ratio).

  Specific examples of the aliphatic polyamide used in the polyamide composition of the present invention include nylon 4, nylon 6, nylon 7, nylon 11, nylon 12, nylon 66, nylon 46, and copolymers and mixtures thereof. An aliphatic polyamide resin is mentioned. Preferred aliphatic polyamide resins are nylon 6 and nylon 66. The blending amount of the aliphatic polyamide is 1 to 50 parts by weight, preferably 2 to 30 parts by weight, and more preferably 2 to 10 parts by weight with respect to 100 parts by weight of the polyamide of the present invention.

  The shape of the aliphatic polyamide chip used in the present invention may be any of a cylinder shape, a square shape, a spherical shape, a flat plate shape, and the like. The average particle size is preferably in the same range as that of the polyamide of the present invention. The same applies to the weight of the chip.

  The polyamide composition of the present invention can be obtained by mixing the polyamide of the present invention and the above aliphatic polyamide by a conventionally known method. For example, the polyamide chip of the present invention and the above-mentioned aliphatic polyamide chip are dry blended with a tumbler, V-type blender, Henschel mixer or the like, and the dry blended mixture is 1 with a single screw extruder, twin screw extruder, kneader or the like. Examples thereof include those melt-mixed more than once, and those obtained by solid-phase polymerization of the melt mixture under a high vacuum or an inert gas atmosphere as necessary.

Further, the polyamide composition of the present invention may have a shape obtained by molding a melt mixture of the polyamide of the present invention and an aliphatic polyamide. The molded state is not limited to a strand shape, a chip shape, or a cylinder shape, and may be a hollow molded body shape, a sheet shape, a film shape, or a pulverized product thereof, and the shape is not particularly limited.
The above-mentioned various additives and resins can be added to the polyamide composition of the present invention.
And the polyamide composition of this invention can be used for said uses, such as a sheet | seat and a film.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. The main characteristic value measuring methods in this specification will be described below.

(1) Relative viscosity (RV) of polyamide
0.25 g of a sample was dissolved in 25 ml of 96% sulfuric acid, and 10 ml of this solution was measured at 20 ° C. with an Ostwald viscosity tube and obtained from the following formula.

RV = t / t ₀
(Where t _{0 is the} number of seconds that the solvent is dropped, t is the number of seconds that the sample solution is dropped)

(2) Structural analysis of phosphorus compound in polyamide ( ³¹ P-NMR method)
340-350 mg of a sample was dissolved in 2.5 ml of a mixed solvent of heavy benzene / 1,1,1,3,3,3-hexafluoroisopropanol = 1/1 (vol ratio) at room temperature, and tri (t-butylphenyl) phosphorus An acid (hereinafter abbreviated as TBPPA) is added as P to 100 ppm with respect to the polyamide resin, 0.1 ml of trifluoroacetic acid is added at room temperature, and 30 minutes later, ³¹ P is added using a Fourier transform nuclear magnetic resonance apparatus (AVANCE500 manufactured by BRUKER). -NMR analysis was performed. The ³¹ P resonance frequency is 202.5 MHz, the detection pulse flip angle is 45 °, the data acquisition time is 1.5 seconds, the delay time is 1.0 second, the integration number is 1000 to 20000 times, the measurement temperature is room temperature, and the proton is completely decoupled. Analysis was performed under ring conditions.

  From the obtained NMR chart, the peak integrated value of each phosphorus compound is calculated, and the moles of the phosphorus compound represented by the structural formula (formula 1) and the phosphorus compound represented by the structural formula (formula 2) from the following formula A: The ratio was determined.

Molar ratio of phosphorus compound = XP1 / XP2 (formula A)

(XP1 is the peak integral value of the phosphorus compound represented by the structural formula (formula 1), and XP2 is the peak integral value of the phosphorus compound represented by the structural formula (formula 2).)

  Next, the P peak integrated value corresponding to TBPPA (tri (t-butylphenyl) phosphoric acid) is defined as 100 ppm, and the total of all the P peak integrated values in the polyamide observed in the region of 15 ppm to -15 ppm. The P peak integral value PN is calculated.

  Next, P peak relative values (Ps) of all phosphorus compounds observed in the NMR spectrum are obtained from the following formula B.

P peak relative value (Ps) = PN / PC (formula B)

(PN is the total P peak integral value (ppm) of polyamide, and PC is the phosphorus atom content (ppm) in the polyamide. Here, the phosphorus atom content PC in the polyamide is determined by the analysis method of (4) below. (If the P peak relative value is greater than 1, P peak relative value = 1)

  Next, the ratio (P1r) of the phosphorus compound detected in the structure of the structural formula (formula 1) in the polyamide and the ratio (P2r) of the phosphorus compound detected in the structure of the structural formula (formula 2) are expressed by the following formula C, Calculate from D.

P1r = Ps × (peak integration value XP1 of phosphorus compound represented by structural formula (formula 1)) / PN (formula C)

P2r = Ps × (peak integration value XP2 of phosphorus compound represented by structural formula (formula 2)) / PN (formula D)

  In addition, when the P peak relative value is smaller than 1, the total value of the proportions of the respective phosphorus compounds in the polyamide does not become 100. This is because there is a phosphorus compound that does not dissolve in the preparation of the polyamide solution by the above method. It is.

  In the polyamides used in Examples and Comparative Examples, the phosphorus compound corresponding to the structural formula (Formula 1) is hypophosphorous acid (the following (Chemical Formula 11)), and the peak due to this structure is in the range of 9 to 12 ppm. It was seen in. Further, the phosphorus compound corresponding to the structural formula (Formula 2) is phosphorous acid (the following (Chemical Formula 12)), and a peak due to this structure was found in the range of 4 to 7 ppm.

  Next, the phosphorus atom content (P1) derived from the phosphorus compound detected in the structure of the structural formula (formula 1) and the phosphorus atom content derived from the phosphorus compound detected in the structure of the structural formula (formula 2) by the following formula The quantity (P2) is determined.

Phosphorus compound-derived phosphorus atom content (P1) (ppm) detected in the structure of structural formula (Formula 1) = PC × P1r
Phosphorus compound-derived phosphorus atom content (P2) (ppm) detected by the structure of structural formula (Formula 2) = PC × P2r

  FIG. 1 shows the NMR spectrum of P.

(3) Color b value of polyamide chip and molded body (Co-b)
A color meter (Model 1001DP, manufactured by Nippon Denshoku Co., Ltd.) was used to measure the color b value.

(4) Analysis of phosphorous atom content (PC) of polyamide Samples are subjected to dry ash decomposition in the presence of sodium carbonate, or wet-decomposed in sulfuric acid / nitric acid / chlorinated acid or sulfuric acid / hydrogenated water systems to remove phosphorus. Normal phosphoric acid was used. Next, the molybdate is reacted in a 1 mol / L sulfuric acid solution to form phosphomolybdic acid, and this is reduced with hydrazine sulfate. The absorbance at 830 nm of the heteropoly blue produced is a spectrophotometer (Shimadzu Corporation, UV-150). -02) and colorimetrically determined.

(5) Analysis of polyamide Na content (Na), Li content (Li), K content (K) The sample was incinerated with a platinum crucible and evaporated to dryness by adding 6 mol / L hydrochloric acid. . The resultant was dissolved in 1.2 mol / L hydrochloric acid, and the solution was quantified by atomic absorption (AA-640-12, manufactured by Shimadzu Corporation).

(6) Heat treatment of polyamide 20 g of a sample vacuum-dried at 80 ° C. for 16 hours at 1 torr or less is put in a 100 ml glass container (mouth inner diameter 41 mm, trunk outer diameter 55 mm, total height 95 mm), and gear type manufactured by Nagano Scientific Machinery Co., Ltd. Place on the turntable of the aging tester NH-202GT and heat-treat at 120 ° C. for 5 hours in an air atmosphere.

(7) Molding of Stepped Molding Plate Polyamide chips that have been dried under reduced pressure to a moisture content of about 300 ppm or less using a vacuum drier are shown in FIG. 2 using an injection molding machine M-150C-DM type injection molding machine manufactured by Meiki Seisakusho. 3 having a gate part (G) as shown in FIG. 3, 2 mm to 11 mm (A part thickness = 2 mm, B part thickness = 3 mm, C part thickness = 4 mm, D part thickness = 5 mm, E part thickness = A stepped molded plate having a thickness of 10 mm and a thickness of F portion = 11 mm) was injection molded. In order to prevent moisture absorption of the chip during molding, the inside of the molding material hopper was purged with a dry inert gas (nitrogen gas).

As plasticization conditions by the M-150C-DM injection molding machine, the feed screw rotational speed was set to 70%, the screw rotational speed was set to 120 rpm, the back pressure was 0.5 MPa, and the cylinder temperature was set to 260 ° C. The injection pressure and holding pressure were adjusted so that the injection speed and holding pressure were 20%, and the weight of the compact was 146 ± 0.2 g.
The upper limit is set to 10 seconds and 7 seconds for the injection time and the pressure holding time, respectively, and the cooling time is set to 50 seconds. The entire cycle time including the molded body take-out time is about 75 seconds.

Although the temperature of the mold is always controlled by introducing cooling water having a water temperature of 10 ° C., the mold surface temperature at the time of stable molding is around 22 ° C.
The test plate for evaluating the color of the molded body was arbitrarily selected from stable molded bodies on the 11th to 18th shots from the start of molding after introducing the molding material and replacing the resin. A plate with a thickness of 3 mm (part B in FIG. 2) was used for color measurement.

(Metaxylylene group-containing polyamide used in Examples and Comparative Examples)
The polyamide used was made of raw materials such as metaxylylenediamine and adipic acid and additives such as sodium hydroxide (NaOH) and sodium hypophosphite (NaH ₂ PO ₂ .H ₂ O) in a pressure-resistant polycondensation kettle. It is obtained by a batch method in which polycondensation is performed by heating under pressure and normal pressure in the presence.

(Ny-MXD6 (A))
Precisely weighed metaxylylenediamine, adipic acid and water into an adjustment can equipped with a stirrer, a condenser, a thermometer, a dropping funnel and a nitrogen gas introduction tube, and pressurizing and releasing pressure with nitrogen gas The nitrogen substitution was repeated 5 times, and the oxygen content in the atmospheric nitrogen was adjusted to 9 ppm or less. The internal temperature at that time was 80 ° C. Further, NaOH or NaH ₂ PO ₂ .H ₂ O was added as an additive and stirred to obtain a uniform salt aqueous solution. At this time, the oxygen content in the atmospheric nitrogen was maintained at 9 ppm or less.

  This solution is transferred to a reaction can equipped with a stirrer, a partial reducer, a thermometer, a dropping funnel and a nitrogen gas introduction tube, and the temperature is gradually raised at a can internal temperature of 190 ° C. and a can internal pressure of 1.0 MPa, and distilled. Water was removed from the system, and the internal temperature was set to 230 ° C. The reaction time until this time was 4.5 hours. Thereafter, the internal pressure of the can was gradually released over 60 minutes, and returned to normal pressure. The temperature was further raised to 255 ° C., stirred at normal pressure for 20 minutes to reach a predetermined viscosity, and the reaction was completed. Then, it was left to stand for 20 minutes, air bubbles in the polymer were removed, the molten resin was extruded from the bottom of the reaction can, and casting was performed while cooling and solidifying with cold water. The casting time was about 70 minutes, and the temperature of the cooled and solidified resin was 50 ° C. The total amount of sodium hypophosphite and sodium hydroxide was 2.7 times mol of phosphorus atoms. Table 1 shows the characteristics.

(Ny-MXD6 (B))
It was obtained by the same polymerization method as Ny-MXD6 (A) except that the polymerization time was extended. Table 1 shows the characteristics.

(Ny-MXD6 (C))
It was obtained by the same polymerization method as Ny-MXD6 (A) except that the amount of additive used was changed.
The total amount of sodium hypophosphite and sodium hydroxide was 3.4 times moles of phosphorus atoms. Table 1 shows the characteristics.

(Ny-MXD6 / MXDI (D))
It was obtained by the same polymerization method as Ny-MXD6 (A) except that metaxylylenediamine, adipic acid and isophthalic acid were adjusted as raw materials so as to correspond to the compositions described in Table 1.
The total amount of sodium hypophosphite and sodium hydroxide was 2.7 times mol of phosphorus atoms. Table 1 shows the characteristics.

(Ny-MXD6 / MXD / CHDA (E))
It was obtained by the same polymerization method as Ny-MXD6 (A) except that metaxylylenediamine, adipic acid and cyclohexanedicarboxylic acid (CHDA) were adjusted as raw materials so as to correspond to the compositions described in Table 1. .
The total amount of sodium hypophosphite and sodium hydroxide was 2.7 times mol of phosphorus atoms. Table 1 shows the characteristics.

(Ny-MXD6 (F))
Using the same reactor as in the case of Ny-MXD6 (A), changing the amount of additives used, the raw material salt adjustment canister is transferred to the reaction canister without replacing nitrogen gas and the oxygen concentration in the atmosphere remains at about 100 ppm. Then, the temperature inside the can was set to 190 ° C. and the pressure inside the can was set to 1.0 MPa. The temperature in the can and the reaction time so far were almost the same as those of Ny-MXD6 (A). Thereafter, the internal pressure of the can was gradually released over 60 minutes, and returned to normal pressure. The temperature was further raised to 283 ° C., stirred at normal pressure for 20 minutes to reach a predetermined viscosity, and the reaction was completed. Thereafter, casting was performed in the same manner as Ny-MXD6 (A).
The total amount of sodium hypophosphite and sodium hydroxide was 2.7 times mol of phosphorus atoms. Table 1 shows the characteristics.

(Ny-MXD6 (G))
The above phosphorus atom-containing compound and alkali compound were not added and were obtained by the same polymerization method as Ny-MXD6 (A). Table 1 shows the characteristics.

(Ny-MXD6 (H))
The additive was obtained by the same polymerization method as Ny-MXD6 (A) except that lithium hydroxide or lithium hypophosphite was used as an additive.
In addition, as the amount of lithium, the total amount of lithium atoms of lithium hypophosphite and lithium hydroxide was 2.7 times mol of phosphorus atoms. Table 2 shows the characteristics.

(Ny-MXD6 (I))
The additive was obtained by the same polymerization method as Ny-MXD6 (A) except that it was changed to sodium hydroxide or magnesium hypophosphite.
The sodium amount was 2.7 moles of phosphorus atoms as sodium atoms of sodium hydroxide. Table 2 shows the characteristics.

(Ny-MXD6 (J))
The additive was obtained by the same polymerization method as Ny-MXD6 (A) except that it was changed to potassium hydroxide or potassium hypophosphite.
In addition, as the amount of potassium, the total amount of potassium atoms of potassium hypophosphite and potassium hydroxide was 2.7 times mol of phosphorus atoms. Table 2 shows the characteristics.

Example 1
Evaluation was performed by the methods (6) and (7) above using Ny-MXD6 (A).
The results are shown in Table 3.
There was no problem in the hue after heat treatment and the hue of the molded body.

(Example 2)
Evaluation was performed by the methods (6) and (7) above using Ny-MXD6 (B).
The results are shown in Table 3.
There was no problem in the hue after heat treatment and the hue of the molded body.

(Example 3)
Evaluation was carried out by the methods (6) and (7) using Ny-MXD6 (C).
The results are shown in Table 3.
There was no problem in the hue after heat treatment and the hue of the molded body.

(Examples 4 to 8)
Evaluation was carried out by the methods (6) and (7) using various polyamides described in Tables 1 and 2.
The results are shown in Table 3.
There was no problem in the hue after heat treatment and the hue of the molded body.

(Comparative Examples 1 and 2)
Evaluation was performed by the methods (6) and (7) above using Ny-MXD6 (D) and (E).
The results are shown in Table 3.
Both the hue after heat treatment and the hue of the molded product were bad.

  As described above, the polyamide of the present invention has been described based on a plurality of examples. However, the present invention is not limited to the configurations described in the above examples, and the configurations described in the examples are appropriately combined. The configuration can be changed as appropriate without departing from the spirit of the invention.

  Since the polyamide of the present invention has good thermal stability and thermal oxidation stability at the time of drying and molding, it has excellent color tone and is difficult to be colored in the molding process, and the generation of foreign matters such as gel-like substances occurs. Therefore, it can be suitably used as a material for molded articles such as films and sheets, hollow molded containers such as beverage bottles, engineering plastics materials, etc., and these molded articles can be produced with high productivity. . Moreover, it can use as molded objects, such as a film and a sheet, as a composition with aliphatic polyamide.

³¹ P-NMR spectrum of a typical example The top view of the stepped molding board used in the Example of this invention Side view of the stepped molded plate of FIG.

Explanation of symbols

A Part A part of stepped molded plate B Part B part of stepped molded plate C Part C of stepped molded plate
D Part D of stepped molded plate
E Part E of stepped molded plate
F Part of stepped molded plate F part G Gate part of stepped molded plate

Claims (6)

A polyamide having a unit derived from an aliphatic dicarboxylic acid and an aromatic diamine as a main constituent unit, or a polyamide having a unit derived from an aromatic dicarboxylic acid and an aliphatic diamine as a main constituent unit, the polyamide Is dissolved in ³¹ P-NMR measurement solvent, and the structure is analyzed after adding trifluoroacetic acid, the phosphorus atom content (P1) derived from the phosphorus compound detected by the structure of the following structural formula (formula 1) is 10 ppm or more. A polyamide characterized in that.

(Where R ₁ and R ₂ are hydrogen, alkyl group, aryl group, cycloalkyl group or arylalkyl group, and X ₁ is hydrogen) When the polyamide is dissolved in a ³¹ P-NMR measurement solvent and subjected to structural analysis after adding trifluoroacetic acid, the phosphorus atom content (P2) derived from the phosphorus compound detected by the structure of the following structural formula (formula 2) is 30 ppm or more. The polyamide according to claim 1, wherein

(Wherein R ₃ is hydrogen, an alkyl group, an aryl group, a cycloalkyl group or an arylalkyl group, X ₂ and X ₃ are hydrogen) 3. The polyamide according to claim 1, wherein the polyamide contains 50 mol% or more of structural units derived from metaxylylenediamine and dicarboxylic acid in the molecular chain. 3. The polyamide according to claim 1, wherein the polyamide contains at least 50 mol% of a structural unit derived from metaxylylenediamine and adipic acid in the molecular chain. The polyamide according to any one of claims 1 to 4, wherein the polyamide chip has a color b value (Co-b) satisfying the following formula (1).
−5 <(Co−b) <10 (1) A polyamide composition comprising the polyamide according to any one of claims 1 to 5 and an aliphatic polyamide as main components.

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