JP2008208248A - Polyamide composition and polyamide molded article comprising the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a polyamide composition slightly causing a rise in filter back pressure and occurrence of foreign matter during molding and having excellent heat stability during drying and molding, not deteriorating a color tone during mixing and using a recycled product, slightly causing foreign matter such as a gel-like substance and having an excellent productivity during molding and a polyamide molded article comprising the same. <P>SOLUTION: The polyamide composition comprises mainly 100 pts.wt. of an aliphatic polyamide and 0.5-30 pts.wt. of a partial aromatic polyamide and has a total residual phosphorus atom content (PC) in the partial aromatic polyamide of ≥10 ppm and a phosphorus atom content (P4) of ≤150 ppm. P4 is a phosphorus atom content derived from a phosphorus compound detected as a pyrophosphate structure when the partial aromatic polyamide is dissolved in a solvent for<SP>31</SP>P-NMR measurement, mixed with trifluoroacetic acid and a structural analysis is carried out. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a polyamide composition suitably used as a material such as a molded article such as a film or sheet, a hollow molded container such as a beverage bottle, or an engineering plastics material, and a polyamide molded article comprising the same. . In particular, the present invention relates to a polyamide composition having little increase in filter back pressure and generation of foreign matter at the time of molding, good thermal stability when drying or molding them, and excellent productivity at the time of molding, and a polyamide molded body 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 degradation of the 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 occurrence of gelation of 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 the gelation of polyamide, they are not satisfactory, and the reduction of clogging that affects the increase in the back pressure of the filter during molding of the polyamide composition has not been solved. Furthermore, depending on the molding conditions such as drying conditions, molding temperature, and melting time, coloring and gelation and the generation of foreign matters resulting from this, abnormal appearance of the molded product, or deterioration of transparency may occur, and a solution is desired. Yes.
JP 49-45960 A JP-A-49-53945 Japanese Patent Laid-Open No. 45-11836 JP-A-45-35667 Japanese Patent Laid-Open No. 45-12986 JP-A-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 little increase in filter back pressure and foreign matter during molding, has good thermal stability during drying and molding, and is used when mixing recycled products. Another object of the present invention is to provide a polyamide composition excellent in productivity at the time of molding and a polyamide molded product comprising the same, in which the color tone does not deteriorate and the generation of foreign matters such as gels is small.

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 composition of the present invention is a polyamide composition mainly composed of 100 parts by weight of an aliphatic polyamide and 0.5 to 30 parts by weight of a partially aromatic polyamide, and the total remaining phosphorus atoms in the partially aromatic polyamide. The polyamide composition is characterized in that the content (PC) is 10 ppm or more and the phosphorus atom content (P4) is 150 ppm or less.
(However, P4 is phosphorus detected as pyrophosphoric acid represented by the following structural formula (formula 1) when the partial aromatic polyamide is dissolved in a ³¹ P-NMR measurement solvent and trifluoroacetic acid is added, followed by structural analysis. (The phosphorus atom content derived from the compound.)

  The phosphorus atom content (P4) in the partially aromatic polyamide according to the present invention is more preferably 130 ppm or less, still more preferably 100 ppm or less, and most preferably 50 ppm or less. When the content of P4 exceeds 150 ppm, the foreign matter clogging of the filter in the polyamide composition molding process becomes severe, the frequency of filter replacement increases, the productivity decreases, and the amount of foreign matter generated in the obtained molded product Is a problem. Moreover, a lower limit is 5 ppm or more, More preferably, it is 10 ppm or more. In order to suppress the concentration to less than 5 ppm, it is not practical to spend enormous equipment costs to reduce the oxygen concentration in the atmosphere from the raw material preparation step to the polymerization step, the drying step, and the like.

In this case, phosphorus atom content (Px) calculated | required by following formula (1) can be 100 ppm or less.
Px = PC- (P1 + P2 + P3 + P4) (1)
(In the formula, PC is the total residual phosphorus atom content in the partially aromatic polyamide, P1, P2, P3, and P4 are obtained by dissolving the partially aromatic polyamide in ³¹ P-NMR measurement solvent and adding trifluoroacetic acid, Phosphorus compound-derived phosphorus atom content detected as hypophosphorous acid, phosphorus compound-derived phosphorus atom content detected as phosphorous acid, phosphorus compound-derived phosphorus atom detected as phosphoric acid when structural analysis is performed Content, phosphorus atom content derived from a phosphorus compound detected as pyrophosphate (unit: ppm).
In addition, the residual phosphorus atom content PC, P1, P2, P3 and P4 in the partially aromatic polyamide was measured by a structural analysis ³¹ P-NMR method of a phosphorus compound described later. Further, Px, PC, P1, P2, P3 and P4 are contents with respect to the weight of the polyamide.

  The phosphorus atom content (Px) determined by the above formula (1) is more preferably 70 ppm or less, still more preferably 60 ppm or less, and most preferably 50 ppm or less. When the phosphorus atom content (Px) exceeds 100 ppm, foreign matter clogging of the filter in the polyamide composition molding process becomes severe, the frequency of filter replacement increases, and the productivity decreases. This is a problem because the amount of foreign matter generated increases. Moreover, a lower limit is 1 ppm or more, More preferably, it is 5 ppm or more. In order to suppress it to less than 1 ppm, it is not practical to require a huge equipment cost to reduce the oxygen concentration in the atmosphere from the raw material preparation step to the polymerization step, the drying step, and the like.

  The phosphorus atom content (P4) derived from the phosphorus compound detected as pyrophosphoric acid represented by the structural formula (formula 1) in the partially aromatic polyamide is 150 ppm or less, and the phosphorus obtained by the formula (1) When the atomic content (Px) is 100 ppm or less, it is even more effective for reducing the filter clogging, and such a polyamide composition is an optimal polyamide for long-time continuous molding.

  A filter containing a phosphorus compound detected as pyrophosphoric acid present in a partially aromatic polyamide or a phosphorus compound that does not dissolve in the measurement solvent (phosphorus compound whose phosphorus atom content is expressed as Px). It is thought that it becomes a causative substance clogged up.

  In this case, the aliphatic polyamide is nylon 6, and the partially aromatic polyamide can be a polyamide containing 50 mol% or more of structural units derived from metaxylylenediamine and adipic acid in the molecular chain.

  In this case, a recovered product of the polyamide molded product from the polyamide composition can be contained.

  In this case, the water content can be 200-2000 ppm.

  In this case, it can be set as the polyamide molded object formed by shape | molding the said polyamide composition.

  In this case, the polyamide molded body of the present invention may be a sheet-like product.

  In this case, the polyamide molded body of the present invention may be a stretched film formed by stretching the sheet-like material in at least one direction.

  The polyamide composition of the present invention has little increase in filter back pressure and foreign matter generation at the time of molding, has good thermal stability and thermal oxidation stability at the time of drying and molding, and has excellent color tone, and molding process It is difficult to be colored with a small amount of foreign matter such as gel-like materials, so it is suitably used as a material for sheet-like materials, molded products such as stretched films, engineering plastics materials, etc. Can be manufactured.

Hereinafter, embodiments of the polyamide composition of the present invention and a polyamide molded body comprising the same will be specifically described.
(Aliphatic polyamide)
Examples of the aliphatic polyamide used in the polyamide composition of the present invention include polyamides obtained by ring-opening polymerization from lactams such as ε-caprolactam, enantolactam, lauryl lactam, ω-aminoheptanoic acid, ω-aminoundecanoic acid, etc. Polyamides obtained by polycondensation of aminocarboxylic acids of the above, polyamides obtained by polycondensation of nylon salts of diamines and dicarboxylic acids, and various lactams described above, aminocarboxylic acids, nylon salts of diamines and dicarboxylic acids and And a polyamide copolymer obtained by copolycondensation of those appropriately mixed. Specific examples of diamines include ethylenediamine, trimethylenediamine, hexamethylenediamine, metaxylylenediamine, paraxylylenediamine, cyclohexanediamine, aliphatic diamines such as 1,3-bisaminomethylcyclohexane, and alicyclic diamines. It is done. Specific examples of the dicarboxylic acid include malonic acid, succinic acid, glutaric acid, adipic acid, 1,4-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid and other aliphatic dicarboxylic acids, alicyclic dicarboxylic acids, aromatic Group dicarboxylic acid and the like.

  Specific examples include aliphatic polyamides such as nylon 4, nylon 6, nylon 7, nylon 11, nylon 12, nylon 66, nylon 46, and copolymers and mixtures thereof. Preferred aliphatic polyamides are nylon 6 and nylon 66.

  The aliphatic polyamide used in the present invention is produced by a known method. For example, it is produced by a method in which lactam is polymerized while being heated under pressure in the presence of a water solvent and removing added water and condensed water. Further, it is produced by a method in which a nylon salt composed of diamine and dicarboxylic acid is heated under pressure in the presence of a water solvent and polymerized while removing added water and condensed water. Furthermore, it can also be produced by a method in which diamine is directly added to molten dicarboxylic acid and polycondensed under normal pressure. In any case, a polymer having a higher molecular weight by solid-phase polymerization after melt polymerization can also be used.

  The relative viscosity of the aliphatic polyamide used in the present invention is preferably 1.7 to 5.5, and more preferably 1.9 to 5.0. When the relative viscosity is less than 1.7, the molecular weight of the aliphatic polyamide is low, and when it is formed into a molded product such as a film, the required mechanical strength is not exhibited, and the melt viscosity is low, resulting in inconvenience during molding. . A relative viscosity exceeding 5.5 is not preferable because the melt viscosity of the aliphatic polyamide is high and the molding machine is overloaded and difficult to mix.

(Partial aromatic polyamide)
In addition, the partially aromatic polyamide used in the polyamide composition of the present invention is derived from a polyamide having a unit derived from an aliphatic dicarboxylic acid and an aromatic diamine as a main constituent unit or an aromatic dicarboxylic acid and an aliphatic diamine. Is a polyamide containing 50 mol% or more, preferably 60 mol% or more, particularly preferably 70 mol% or more of any of the polyamides whose main structural units are the main constituent units.

  In the case where the partially aromatic polyamide according to the present invention is a polyamide having a unit derived from an aliphatic dicarboxylic acid and an aromatic diamine as a main structural unit, the aromatic diamine component constituting the polyamide is metaxylylene diene. Examples thereof include amines, paraxylylenediamine, 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 partially aromatic polyamide according to the present invention is a polyamide having a main structural unit derived from an aromatic dicarboxylic acid and an aliphatic diamine, the aromatic dicarboxylic acid component constituting the polyamide is terephthalic acid. , Isophthalic acid, 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, an alicyclic diamine other than the above aromatic diamine and aliphatic diamine can also be used as a diamine component constituting the partially aromatic polyamide according to the present invention. Examples of the alicyclic diamine include alicyclic diamines such as cyclohexanediamine, 1,3-bis (aminomethyl) cyclohexane, and 1,4-bis (aminomethyl) cyclohexane.

  Moreover, as a dicarboxylic acid component which comprises the partially aromatic polyamide which concerns on this invention, alicyclic dicarboxylic acid can also be used other than the above aromatic dicarboxylic acid and aliphatic dicarboxylic acid. 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 according to 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. A metaxylylene group-containing polyamide containing at least 50 mol% or more, more preferably 60 mol% or more, particularly preferably 70 mol% or more in the molecular chain.

  Further, the partially aromatic polyamide according to the present invention contains structural units derived from a polybasic carboxylic acid having 3 or more bases such as trimellitic acid and pyromellitic acid within a substantially linear range. Also good.

  Examples of these partially aromatic polyamides include homopolymers such as polymetaxylylene adipamide, polymetaxylylene sebacamide, polymetaxylylene speramide, and metaxylylenediamine / adipic acid / isophthalic acid copolymer Copolymer, metaxylylene / paraxylylene adipamide copolymer, metaxylylene / paraxylylene piperamide copolymer, metaxylylene / paraxylylene azelamide copolymer, metaxylylenediamine / adipic acid / isophthalic acid / ε-caprolactam Examples thereof include a copolymer and a metaxylylenediamine / adipic acid / isophthalic acid / ω-aminocaproic acid copolymer.

  In addition, other preferable examples of the partially aromatic polyamide according to the present invention include at least 50 mol of a structural unit derived from an aliphatic diamine and at least one acid selected from terephthalic acid or isophthalic acid in the molecular chain. % Or more, more preferably 60 mol% or more, particularly preferably 70 mol% or more.

  Examples of these partially aromatic 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 preferable examples of the partially aromatic polyamide according to 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, and aminocaproic acid. , An aminocarboxylic acid such as aminoundecanoic acid, an aromatic aminocarboxylic acid such as para-aminomethylbenzoic acid, etc. used as a copolymerization component, at least selected from an aliphatic diamine and terephthalic acid or isophthalic acid Polyamide containing at least 50 mol%, more preferably 60 mol% or more, and particularly preferably 70 mol% or more of a structural unit derived from one kind of acid in the molecular chain.

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

  The partially aromatic polyamide according to the present invention is basically a conventionally known polyamide obtained by a melt polycondensation method in the presence of water or a melt polycondensation method in the absence of water, or these melt polycondensation methods. Can be produced by a method such as solid phase polymerization. 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 a partially aromatic polyamide according to 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, it is preferable that the tank for storing metaxylylenediamine and the tank for storing adipic acid have a nitrogen gas atmosphere separately, and the oxygen concentration in the nitrogen gas atmosphere is 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 (P4) derived from pyrophosphoric acid remaining in the obtained polyamide or the phosphorus atom obtained from the formula (1) The content (Px) increases, causing filter clogging at the time of molding, which causes a problem. Moreover, the heat stability of the obtained partial aromatic polyamide will also be 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 for lowering the oxygen concentration, a method of bubbling 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 derived from pyrophosphoric acid (P4) remaining in the obtained partially aromatic polyamide, or the phosphorus atom content obtained from the formula (1) (Px) increases, causing filter clogging during molding and causing a problem. Moreover, the heat stability of the obtained partial aromatic polyamide will also be 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. The lower limit is preferably a temperature at which the salt does not solidify, and is 30 ° C. or higher, more preferably 40 ° C. or higher.

  Next, the prepared aqueous salt solution is transferred to a polymerization vessel and subjected to polycondensation. 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. Further, the temperature was 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 1.5 hours, more preferably within 1.3 hours, and even more preferably within 1.0 hour. The polymerization time is the time for the polycondensation reaction at normal pressure.

When the target viscosity was reached, stirring was stopped and allowed to stand to remove bubbles in the polymer. The defoaming time is preferably within 30 minutes, more preferably within 20 minutes, and even more preferably within 10 minutes. Further, when the melting point of the partially aromatic polyamide according to the present invention is less than 250 ° C., the molten polymer temperature at the time of defoaming can be maintained at 255 ° C. or less, preferably 253 ° C. or less, more preferably 250 ° C. or less. is important. Further, when the melting point of the partially aromatic polyamide is 250 ° C. or higher, the molten polymer temperature at the time of defoaming is 15 ° C. higher than the melting point, preferably 13 ° C. higher than the melting point, more preferably the melting point It is important to maintain below 10 ° C higher temperature. Exceeding such conditions is not preferable because the partial aromatic polyamide is further deteriorated by heat and the content of a phosphorus compound having a pyrophosphoric acid structure that causes filter clogging increases.
Next, 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. At this time, if the time required for casting is long, it is greatly affected by thermal oxidative deterioration at the take-out port, the resin in the can etc. is thermally deteriorated, gelled product is formed or colored, and the filter- Undesirably, clogging substances increase. In addition, if the casting time is too short, the temperature of the strand-shaped polymer coming out from the outlet becomes too high, so that it is likely to be subject to thermal oxidative degradation of the resin and additives, 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 100 minutes, more preferably 15 to 80 minutes, and further preferably 15 to 60 minutes. When the melting point of the partially aromatic polyamide according to the present invention is less than 250 ° C., the molten polymer temperature in the reaction vessel during casting and between the reaction vessel and the casting die is 255 ° C. or less, preferably 253 ° C. or less, more preferably It is important to keep it below 250 ° C. When the melting point of the partially aromatic polyamide is 250 ° C. or higher, the temperature of the molten polymer in the reaction vessel during casting and between the reaction vessel and the casting die is 15 ° C. or higher, preferably 13 ° C. higher than the melting point. It is important to keep the temperature below a high temperature, more preferably below 10 ° C. above the melting point. If the molten polymer temperature is out of the above temperature condition, the content of a phosphorus compound having a pyrophosphate structure which causes clogging of the filter increases, which is not preferable. The strand polymer temperature is preferably in the range of 20 to 70 ° C, more preferably 30 to 65 ° C. 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.
Here, the melting point of the partially aromatic polyamide was increased from room temperature to 20 ° C./min for 10 mg of the crystallized and dried sample from the polyamide chip using a differential scanning calorimeter DSC-50 (manufactured by Shimadzu Corporation). Measured while warm.

  In addition, the gelation time of the partially aromatic polyamide according to the present invention is preferably 3 hours or longer, preferably 5 hours or longer, and more preferably 7 hours or longer. When a partially aromatic polyamide having a gelation time of less than 3 hours is used, gelation gradually occurs in the melt molding machine in continuous molding for a long time, the melt viscosity of the melt increases, and the back pressure increases greatly. This is a problem because the filter replacement period becomes very short due to the rapidity, resulting in a decrease in productivity and economy. Moreover, the molded object from such a polyamide composition contains the colored foreign material by gelled material, and a color also worsens. In particular, in stretched films and biaxially stretched hollow molded products obtained by stretch molding, the portions where gel-like materials exist are not normally stretched and become thick, causing thickness unevenness, and having no commercial value. Many bodies are generated and the yield may be deteriorated. In the worst case, only a molded body having no commercial value may be obtained.

  The gelation time is ideally infinite, but is preferably 500 hours or less, more preferably 200 hours or less, and particularly preferably 100 hours or less. Production of partially aromatic polyamides with a gelation time of 500 hours or more, using highly refined raw materials, requiring large amounts of deterioration inhibitors, and keeping polymerization temperature low Sexual problems may occur.

  The polyamide having a gelation time of 3 hours or longer according to the present invention can be produced, for example, as follows. That is, as an example, the molar ratio of the amino terminal group to the carboxyl terminal group of the polyamide may be slightly shifted from equimolar. When the raw material is added so that the amount of carboxyl end groups is excessive, the ratio of amino end group amount (equivalent / ton) / carboxyl end group amount (equivalent / ton) of the polyamide is 0.9800-0. 9990, preferably 0.9850 to 0.9980, more preferably 0.9900 to 0.9975. Moreover, when manufacturing by adding a raw material so that the amount of amino terminal groups may become excess, ratio of the amount of amino terminal groups (equivalent / ton) / carboxyl terminal group (equivalent / ton) is 1.0010-1. 0200, preferably 1.0020 to 1.0150, more preferably 1.040 to 1.0025. When the ratio of amino end group amount (equivalent / ton) / carboxyl end group amount (equivalent / ton) is close to 1, the gelation time is less than 3 hours, and the back pressure of the filter is extremely increased, which is not preferable.

  Although it is preferable to add a phosphorus compound and an alkali metal compound during the production of the partially aromatic polyamide, the total residual phosphorus atom content (PC) and alkali metal atom content (M) in the partially aromatic polyamide are represented by the following formula ( It is preferable to satisfy the ranges of 2) and (3). 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 added together with the content in the obtained polyamide as addition amount at the time of production of the polyamide. Is also a desirable range.

10 ≦ PC <400ppm (2)
1.2 <(M / PC) molar ratio <7 (3)

  With respect to the total residual phosphorus atom content (PC), the lower limit is more preferably 15 ppm, and even more preferably 20 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. When the total residual phosphorus atom content (PC) is less than 10 ppm, the color tone of the polymer is deteriorated and the thermal stability is inferior, which is not preferable. On the other hand, if the total residual phosphorus atom content (PC) is increased to 400 ppm or more, the raw material cost for the additive increases, which contributes to an increase in cost or increases the clogging of the filter during melt molding. There is a concern that productivity will be lowered in the subsequent process. On the other hand, if the M / PC molar ratio is 1.2 or less, there is a risk that the viscosity will increase drastically and the gelled product will be mixed. On the other hand, when the M / PC molar 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 the phosphorus compound used in the production of the partially aromatic polyamide according to the present invention for obtaining a polyamide composition having good thermal stability and thermal oxidation stability during drying and molding, (A-1), ( A compound represented by A-3) is preferred. 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,

Or

And hydrolysates thereof, and condensates of the above phosphinic 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 the production of the partially aromatic polyamide according to 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 partially aromatic polyamide according to the present invention, raw materials before polymerization of the partially aromatic polyamide, these are added during the polymerization, or are melt-mixed into the polymer. May be.

  These compounds may be added simultaneously or separately.

  The relative viscosity of the partially aromatic polyamide according to the present invention is in the range of 1.5 to 4.0, preferably 1.5 to 3.0, and more preferably 1.7 to 2.5. When the relative viscosity is 1.5 or less, the molecular weight is too small, and the mechanical properties of a molded article such as a film made of the polyamide composition of the present invention may be inferior. 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 partially aromatic polyamide chip according to 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.

(Polyamide composition)
The mixing ratio of the aliphatic polyamide and the partially aromatic polyamide constituting the polyamide composition of the present invention is 0.5 to 30 parts by weight, preferably 0.8 to 100 parts by weight of the aliphatic polyamide. It is preferably 5 to 20 parts by weight. (0.5 to 30 parts by weight of partially aromatic polyamide with respect to 100 parts by weight of aliphatic polyamide is calculated as aliphatic polyamide / partial aromatic polyamide = 99.5 / 0.5 to 76.9 / 23. 1 (part by weight))
By setting the partially aromatic polyamide in the range of 0.5 to 30 parts by weight with respect to 100 parts by weight of the aliphatic polyamide, the polyamide composition is excellent in impact resistance and bending fatigue resistance, and a sheet comprising this polyamide composition And stretched films are also excellent in impact resistance and bending fatigue resistance.

  In the polyamide composition of the present invention, the aliphatic polyamide is nylon 6, and the partially aromatic polyamide is a polyamide containing 50 mol% or more of structural units derived from metaxylylenediamine and adipic acid in the molecular chain. It is a polyamide composition characterized by being.

Further, the polyamide composition of the present invention can contain a recovered product of the polyamide molded product from the polyamide composition, and the content thereof is 30% by weight with respect to the mixture composed of the aliphatic polyamide and the partially aromatic polyamide. Hereinafter, it is preferably 25% by weight or less.
When the content of the recovered product exceeds 30% by weight, the hue of the polyamide molded product is deteriorated, which causes a problem, and the deterioration of the quality is observed due to the mixing of a gelled product or the like.
The recovered product is preferably a recovered product of a polyamide molded body from the polyamide composition of the present invention.

  Here, the recovered product of the polyamide molded body constituting the polyamide composition of the present invention is formed into a form such as a molded body or a sheet after the polyamide composition is heated and melted by a melt molding machine such as an injection molding machine or an extrusion molding machine. After that, it is recovered without shipping as a product, and is again mixed with the polyamide composition of the virgin raw material and used for molding, and is sometimes referred to as “recovered product”. Specifically, the recovered product is a product, an intermediate product such as an unstretched sheet, a product that does not meet the product standards, a burr such as a runner generated at the time of molding, an ear portion generated at the time of forming a stretched film, or the like. These recovered products are required to be about 1 to 10 mm in size by a method such as cutting, pulverization, melt extrusion, or compression molding, and a size approximately comparable to the size of the virgin raw material is preferable.

  The water content of the polyamide composition of the present invention is preferably 250 to 1800 ppm, more preferably 300 to 1500 ppm. When the water content is less than 200, the melt viscosity at the time of melting increases significantly, so the filter back pressure rises more severely, the filter replacement cycle becomes very short, and the productivity and economy are reduced. It becomes a problem. Moreover, the molded object from such a polyamide composition contains the colored foreign material by gelled material, and a color also worsens. On the other hand, when it exceeds 2000 ppm, the melt viscosity is drastically lowered, resulting in deterioration of transparency and mechanical properties of the obtained polyamide molded product.

  When the moisture content of the polyamide composition is dried, the moisture content of the polyamide composition is periodically measured by measuring the moisture content of the sample taken out from the drying apparatus, and drying is finished so that the moisture content is within the above range. The moisture-absorbing polyamide composition is dried to 200 ppm or less, and then can be managed by a method of replenishing moisture by absorbing moisture and adjusting the moisture content to fall within the above moisture content range.

  The polyamide composition of the present invention can be obtained by mixing an aliphatic polyamide and a partially aromatic polyamide, or a recovered product of a polyamide molded product, with a conventionally known method. For example, aliphatic polyamide chips and partially aromatic polyamide chips are dry blended with a tumbler, V-type blender, Henschel mixer, etc., and the dry blended mixture is once or more with a single screw extruder, twin screw extruder, kneader, etc. What melt-mixed and also what solid-phase-polymerized the molten mixture under high vacuum or inert gas atmosphere as needed are mentioned.

  Further, the polyamide composition of the present invention may have a shape obtained by molding a molten mixture of an aliphatic polyamide and a partially aromatic polyamide. The molded state is not limited to a strand shape, a chip shape, or a cylinder shape, but may be a sheet shape, a film shape, or a pulverized product thereof, and the shape is not particularly limited.

  The polyamide composition of the present invention includes a lubricant, an antistatic agent, an antioxidant, an oxygen absorbent, an oxygen scavenger, an antiblocking agent, a stabilizer, a dye, a pigment, silica, barium sulfate, and magnesium oxide as necessary. Additives such as inorganic fine particles such as alumina and zeolite, polymeric organic lubricants such as acrylic and polystyrene, modified polyolefins, ionomer resins, thermoplastic resins such as elastomers, glass fibers, carbon fibers, calcium carbonate, mica Further, fibers such as potassium titanate or fillers can be added.

  The polyamide composition of the present invention is a dry blend product, or a melt blend product that has been previously melt-mixed and pelletized by an extruder or the like as a raw material by various molding techniques such as an injection molding method, an extrusion molding method, and a blow molding method. It can be molded into the desired final molded body.

  Examples of the polyamide molded body include automobile parts, machine equipment parts, sheets, films (single layer, multilayer), laminates with paper, blow bottles, etc., and secondary processed products such as trays and pouches. Moreover, the polyamide composition of the present invention can also be used as a component layer having various forms such as a film shape and a coating film shape in a composite molded body such as a laminated molded body or a laminated film.

  Biaxially oriented polyamide film mainly composed of aliphatic polyamide is tough, excellent in impact resistance and bending fatigue resistance, and excellent in gas barrier properties, pinhole resistance, transparency, printability, etc. Widely used as packaging materials for various foods such as liquid foods, hydrated foods, frozen foods, retort foods, pasty foods, livestock and fishery products. The heat degradation of the above-mentioned polyamide deteriorates transparency due to coloring due to heat deterioration, resulting in poor color appearance and poor appearance of the final bag product. In addition, the occurrence of foreign matter and fish eyes due to gelation due to thermal deterioration causes poor appearance such as ink loss during printing and foreign matter contamination, and poor adhesiveness due to uneven application of adhesive during secondary processing on bag products. The bag-making property is poor. Improvement of the thermal stability of the polyamide raw material greatly contributes to the solution of the above problems.

  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 the solvent falls, t : Sample solution dropping seconds)
(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 About 100 ppm of acid (hereinafter abbreviated as TBPPA) is added to the resin as P, 0.1 ml of trifluoroacetic acid is further added at room temperature, and 30 minutes later, in a polyamide using a Fourier transform nuclear magnetic resonance apparatus (AVANCE500 manufactured by BRUKER). The structural analysis ( ³¹ P-NMR method) of the phosphorus compound 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.

  The peak integrated value of each phosphorus compound is calculated from the obtained NMR chart, and P1 is detected as hypophosphorous acid in polyamide from the following formulas (F) to (I) as follows. Derived phosphorus atom content (ppm), P2: phosphorus atom content derived from phosphorus compound detected as phosphorous acid in polyamide (ppm), P3: phosphorus derived from phosphorus compound detected as phosphoric acid in polyamide Atom content (ppm), P4: The phosphorus atom content (ppm) derived from the phosphorus compound detected as pyrophosphoric acid in the polyamide was calculated.

  First, assuming that the P peak integral value of the phosphorus compound corresponding to TBPPA is 100 ppm, the total P peak integral value, which is the sum of the P peak integral values corresponding to each phosphorus compound in the polyamide, observed in the region of 15 ppm to −15 ppm. PN is calculated.

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

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

(PN is the total P peak integral value (ppm) of polyamide, and PC is the total residual P content (ppm) in the polyamide. Here, the total residual P content PC in the polyamide is the analysis method of (3) below. (If the P peak relative value is greater than 1, P peak relative value = 1)

  Next, the ratio (P1r) of the phosphorus compound derived from the phosphorus compound detected as hypophosphorous acid in the polyamide, the ratio (P2r) of the phosphorus compound derived from the phosphorus compound detected as phosphorous acid, and detected as phosphoric acid The ratio (P3r) of the phosphorus compound derived from the phosphorus compound and the ratio (P4r) of the phosphorus compound derived from the phosphorus compound detected as pyrophosphoric acid are determined from the following formulas B, C, D and E.

P1r = Ps × (P peak integrated value XP1 of phosphorus compound derived from hypophosphorous acid) / PN (Formula B)
P2r = Ps × (P peak integrated value XP2 of phosphorus compound derived from phosphorous acid) / PN (formula C)
P3r = Ps × (P peak integrated value XP3 of phosphorus compound derived from phosphoric acid) / PN (formula D)
P4r = Ps × (P peak integral value XP4 of phosphorus compound derived from pyrophosphate) / PN (formula E)

  Next, the phosphorus atom content (P1) derived from hypophosphorous acid remaining in the polyamide, the phosphorus atom content (P2) derived from phosphorous acid remaining in the polyamide, and the polyamide remaining by the following formula The phosphorus atom content (P3) derived from phosphoric acid and the phosphorus atom content (P4) derived from pyrophosphoric acid remaining in the polyamide are determined.

Phosphorus compound-derived phosphorus atom content detected as hypophosphorous acid in polyamide (P1) = PC × P1r
.... (Formula F)
Phosphorus compound-derived phosphorus atom content detected as phosphorous acid in polyamide (P2) = PC × P2r
.... (Formula G)
Content of phosphorus atom derived from phosphorus compound detected as phosphoric acid in polyamide (P3) = PC × P3r
.... (Formula H)
Phosphorus compound-derived phosphorus atom content detected as pyrophosphoric acid in polyamide (P4) = PC × P4r
.... (Formula I)

  Here, hypophosphorous acid (following (Chemical Formula 8)) corresponds to P1, the peak due to this structure is in the range of 9 to 12 ppm, and P2 corresponds to phosphorous acid (Chemical Formula below) 9)), the peak attributed to this structure is in the range of 4-7 ppm, and P3 corresponds to phosphoric acid (the following (Chemical Formula 10)), and the peak attributed to this structure is in the range of 0-2 ppm Furthermore, pyrophosphoric acid (following (Chemical Formula 11)) corresponds to P4, and a peak due to this structure was observed in the range of -12 to -10 ppm.

  Subsequently, phosphorus atom content (Px) was calculated | required by following formula (1).

  Px = PC- (P1 + P2 + P3 + P4) (1)

(In the formula, PC is the total residual phosphorus atom content in the polyamide, and P1, P2, P3, and P4 are respectively obtained by dissolving the polyamide in a ³¹ P-NMR measurement solvent, treating with trifluoroacetic acid, and analyzing the structure. Phosphorus compound-derived phosphorus atom content detected as phosphoric acid, phosphorus compound-derived phosphorus atom content detected as phosphorous acid, phosphorus compound-derived phosphorus atom content detected as phosphoric acid, pyrophosphoric acid detected The phosphorus atom content derived from the phosphorus compound is expressed in ppm)

  FIG. 1 shows the NMR spectrum of P.

(3) Total residual phosphorus atom content in the polyamide (PC)
The sample was subjected to dry ashing decomposition in the presence of sodium carbonate, or wet decomposition in sulfuric acid / nitric acid / chlorinated acid system or sulfuric acid / hydrogen peroxide water system, and phosphorus was converted into normal phosphoric acid. 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.

(4) Analysis of polyamide Na content (Na) A sample was incinerated and decomposed with a platinum crucible, and 6 mol / L hydrochloric acid was added to evaporate to dryness. 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).
(5) 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.

(6) Water content of polyamide (measured with Karl Fischer trace moisture measuring device CA-100 type and moisture vaporizer VA-100 manufactured by Mitsubishi Chemical)
A moisture vaporizer VA-100 manufactured by Mitsubishi Chemical was previously dried in two drying cylinders (filled with silica gel and phosphorus pentoxide), and the heating furnace was heated to 180 ° C. while flowing nitrogen gas at a flow rate of 250 ml / min. The sample board was put into a heating furnace, and after confirming that the dry nitrogen obtained from the heating furnace and the sample board was anhydrous with a trace moisture measuring device CA-100, 3 g of the sample was previously dried. Weigh accurately in a sample container and immediately place the sample in the sample board. The water vaporized from the sample is transported to a trace moisture measuring device CA-100 by dry nitrogen and subjected to Karl Fischer titration to determine the moisture content.

(7) Back pressure increase test Polyamide whose moisture content was adjusted to 300 ppm was dissolved using a single screw extruder (heater set temperature 285 ° C., average residence time 10 minutes), and GP was used, 3 to 6 g / min. A certain amount was extruded. Foreign matters in the polymer were filtered through a filter having a filtration diameter of 20 μm, and the pressure on the secondary side of the GP was recorded over time. The pressure difference after flowing for 4 hours was applied to the following formula to determine the back pressure increase coefficient (K *).

K * = [ΔP (MPa) / T (hr)] / [Q (kg / hr) / S (cm ² )] (4)
In equation (4),
ΔP (MPa): Pressure after 4 hours of GP secondary pressure-Initial pressure T (hr): Time when polyamide was filtered through a filter (4 hours)
Q (kg / hr): Polyamide discharge amount (3 to 6 g / min)
S (cm ² ): Filtration area of the filter (1.538 cm ² )
(8) Gelation time 3 g of polyamide resin dried under reduced pressure at 100 ° C. for 24 hours was placed in a branch test tube having an internal volume of about 20 ml and subjected to reduced-pressure nitrogen substitution three times, while flowing 30 ml / min of nitrogen gas, The sample was immersed in an oil bath at a constant temperature of 260 ° C., heated, and sampled every 0.5 to 1 hour.

  0.25 g of the heat-treated sample was dissolved in 25 ml of 96% sulfuric acid at room temperature for 16 hours, and the solution was filtered with a glass filter (1G crucible glass filter, pore size 160 to 250 μm, manufactured by Shibata Kagakusha). Thus, the heat treatment time required until the insoluble matter was visually recognized was defined as the gelation time.

(9) Fabrication and properties of stretched polyamide film 0.15 mass of polyamide composition with water content adjusted to a specific value and N, N'-ethylenebisstearylamide (Kyoeisha Chemical Company Light Amide WE-183) %, And then melt extruded through a 400 mesh filter device at a temperature of 260 ° C. from a T die at a temperature of 260 ° C. by an extruder, on a metal roll cooled to 30 ° C., The sheet was electrostatically brought into close contact with a DC high voltage imprint and cooled and solidified to obtain a substantially unoriented sheet having a thickness of 200 μm. The degree of increase in back pressure during extrusion was evaluated as follows.
The sheet cut into a size of about 1 mm was used as a recovered product and used in Example 8 and Comparative Example 3.
The sheet was first stretched in the machine direction at a stretching temperature of 85 ° C. to 2.20 times, then held at 70 ° C., and subsequently stretched in the machine direction at a stretching temperature of 70 ° C. to 1.50 times, Furthermore, this sheet was continuously guided to a stenter, stretched 4.0 times at 130 ° C, heat-fixed at 210 ° C and subjected to 6.1% lateral relaxation treatment, cooled, and both edges were cut. It removed and wound up and the roll-shaped biaxially oriented polyamide-type resin film was obtained. Thereafter, the hue, foreign matter, and film forming property of the obtained biaxially oriented polyamide resin film were evaluated as follows. Table 2 shows the evaluation results of these characteristics.

(Back pressure rise)
The increase in the back pressure of the filter was confirmed by checking the pressure on the secondary side of the 400 mesh filter and evaluating the state after 8 hours as follows.
◎: Almost none ○: Although there is an increase in back pressure, there is no need to interrupt the film formation ×: Severe

(Hue of film)
The hue of the end face of the stretched film roll was observed with the naked eye and evaluated as follows.
◎: Not much different from the hue of the chip before melting ○: A little yellower than the hue of the chip before melting No problem in practical use ×: Colored yellow to brown than the color of the chip before melting XX: Melting It is colored much more brown than the color of the previous chip

(Foreign matter on film)
Foreign objects were observed with the naked eye for 10 sheets of the stretched film 1 m ² and evaluated as follows.
◎: No foreign matter ○: Almost no foreign matter ×: Foreign matter

(Film forming property)
The film forming property in the first stretching step and the second stretching step was evaluated as follows.
○: Good film forming property in both the first stretching step and the second stretching step Δ: Good film forming property in the first stretching step and poor film forming property in the second film forming step ×: Poor film forming property in both steps

(Polycapramide (Ny6) used in Examples and Comparative Examples)
Using a 100 liter batch polymerization kettle, nylon 6 obtained by ring-opening polymerization of ε-caprolactam was used as the polyamide resin. The nylon 6 chip is extracted with hot water using a batch polymerization kettle to reduce the monomer and oligomer contents to 1% by weight, and then dried until the moisture content becomes 0.1% by weight. used. The relative viscosity of the raw material nylon 6 and the stretched film was about 2.8 as measured at 20 ° C. using a 96% concentrated sulfuric acid solution. The surface protrusion forming fine particles (0.45% by weight) used were silica fine particles having a pore volume of 1.6 cc / g and an average particle diameter of 1.8 μm (Silicia 350 manufactured by Fuji Silysia Chemical Co., Ltd.). The mixture was dispersed in an aqueous solution of ε-caprolactam as a raw material with a high-speed stirrer, charged into a polymerization kettle, and dispersed in nylon 6 in the polymerization step.

(Metaxylylene group-containing polyamide used in Examples and Comparative Examples (Ny-MXD6))
(Ny-MXD6 (A))
Precisely metered amounts of metaxylylenediamine, adipic acid and water are added to an adjustment can equipped with a stirrer, a condenser, a thermometer, a dropping funnel, and a nitrogen gas introduction tube, and pressure and release operations are performed 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, sodium hydroxide (NaOH) and sodium hypophosphite (NaH ₂ PO ₂ .H ₂ O) were added as additives and stirred to obtain a uniform aqueous salt 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 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. Thereafter, the polymer was left at 250 ° C. for 10 minutes to remove bubbles in the polymer, and the molten resin was extruded from the bottom of the reaction can and cast while being cooled and solidified with cold water. The casting time was about 50 minutes, and the polymer temperature in the reactor and between the reactor and the die was maintained at about 250 ° C. The resin temperature after cooling and solidification was 50 ° C. The melting point was 237 ° C.

  The ratio of the amino terminal group amount (equivalent / ton) / carboxyl terminal group amount (equivalent / ton) is 0.9900, and the sodium amount is phosphorus atom as the total amount of sodium hypophosphite and sodium hydroxide. 2.7 moles. Evaluation was carried out by the methods (5), (7) and (8). The results are shown in Table 1.

(Ny-MXD6 (B))
It was obtained by the same polymerization method as Ny-MXD6 (A) except that the polymerization time was extended.
Evaluation was carried out by the methods (5), (7) and (8).
The total amount of sodium hypophosphite and sodium hydroxide was 2.7 times mol of phosphorus atoms.
The results are shown in Table 1.

(Ny-MXD6 (C))
It was obtained by the same polymerization method as Ny-MXD6 (A) except that the polymerization time was extended and the amount of additive used was changed.
Evaluation was carried out by the methods (5), (7) and (8).
The total amount of sodium hypophosphite and sodium hydroxide was 1.6 times moles of phosphorus atoms.
The results are shown in Table 1.

(Ny-MXD6 (D))
It was obtained by the same polymerization method as Ny-MXD6 (A) except that the amount of additive used was changed.
Evaluation was carried out by the methods (5), (7) and (8).
The total amount of sodium hypophosphite and sodium hydroxide was 4.0 times moles of phosphorus atoms.
The results are shown in Table 1.

(Ny-MXD6 (E))
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 3.5 times moles of phosphorus atoms. Table 1 shows the characteristics.

(Ny-MXD6 (F))
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 2.7 times mol of phosphorus atoms. Table 1 shows the characteristics.

(Ny-MXD6 / MXDI (G))
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 melting point was 234 ° 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 / MXD / CHDA (H))
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. . However, since the melting point was 250 ° C., the polymer temperature at the time of defoaming and the polymer temperature in the reaction vessel at the time of casting and between the reaction vessel and the die were maintained at about 260 ° 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 (I))
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 285 ° C., and the mixture was stirred at normal pressure for 2 hours and 10 minutes to reach a predetermined viscosity, and the reaction was completed. After leaving at 265 ° C. for 70 minutes to remove bubbles in the polymer, the molten resin was extruded from the bottom of the reaction can and cast in the same manner as Ny-MXD6 (A). The casting time was 110 minutes, and the polymer temperature in the reaction vessel and between the reaction vessel and the die was maintained at about 265 ° C.
The ratio of amino terminal group amount (equivalent / ton) / carboxyl terminal group amount (equivalent / ton) was 1.0, and the sodium amount was phosphorus as the total amount of sodium hypophosphite and sodium hydroxide sodium hydroxide. It was made to become 1.9 times mole of atoms. Evaluation was carried out by the methods (5), (7) and (8). The results are shown in Table 1.

(Ny-MXD6 (J))
The above phosphorus atom-containing compound and alkali compound were not added and were obtained by the same polymerization method as Ny-MXD6 (A). Evaluation was carried out by the methods (5), (7) and (8). The results are shown in Table 1.

(Example 1)
Using the polyamide composition described in Table 2, the evaluation was carried out by the method (9). The results are shown in Table 2. There were no problems with film-forming properties, hue, foreign matter, and increased back pressure.

(Examples 2 to 12)
In the same manner as in Example 1, the polyamide compositions shown in Table 2 were evaluated. The results are shown in Table 2. There were no problems with film-forming properties, hue, foreign matter and increased back pressure.

(Comparative Example 1)
In the same manner as in Example 1, the polyamide compositions shown in Table 2 were evaluated. The results are shown in Table 2. There were no problems with film-forming properties and hue, but foreign matter and increased back pressure were problems.

(Comparative Example 2)
In the same manner as in Example 1, the polyamide compositions shown in Table 2 were evaluated. The results are shown in Table 2. Although there was no problem with the film-forming property and the increase in back pressure, both hue and foreign matter were problems.

(Comparative Example 3)
In the same manner as in Example 1, the polyamide compositions shown in Table 2 were evaluated. The results are shown in Table 2. There was no problem in film forming property, but hue, foreign matter and back pressure increase were problems.

(Comparative Example 4)
In the same manner as in Example 1, the polyamide compositions shown in Table 2 were evaluated. The results are shown in Table 2. Although there was no problem with the film-forming property and the increase in back pressure, both hue and foreign matter were problems.

(Comparative Example 5)
The polyamide compositions shown in Table 2 were evaluated in the same manner as in Example 3 except that the water content was changed. The results are shown in Table 2. Although there was no problem with the hue, foreign matter, and back pressure, the film-forming property was poor.

(Comparative Example 6)
The polyamide compositions shown in Table 2 were evaluated in the same manner as in Example 3 except that the water content was changed. The results are shown in Table 2. Although there was no problem with the hue, foreign matter, and back pressure, the film-forming property was poor.

(Comparative Example 7)
The polyamide compositions shown in Table 2 were evaluated in the same manner as in Example 3 except that the water content was changed. The results are shown in Table 2. Although there was no problem with the hue, foreign matter, and back pressure, the film-forming property was poor.

  As described above, the polyamide composition 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.

  The polyamide composition of the present invention has little increase in filter back pressure and foreign matter generation at the time of molding, has good thermal stability and thermal oxidation stability at the time of drying and molding, and has excellent color tone, and molding process It is difficult to be colored with a small amount of foreign matter such as gel-like materials, so it is suitably used as a material for sheet-like materials, molded products such as stretched films, engineering plastics materials, etc. Can be manufactured.

³¹ P-NMR spectrum of a typical example

Claims (8)

A polyamide composition mainly comprising 100 parts by weight of an aliphatic polyamide and 0.5 to 30 parts by weight of a partially aromatic polyamide, wherein the total residual phosphorus atom content (PC) in the partially aromatic polyamide is 10 ppm or more, phosphorus A polyamide composition having an atomic content (P4) of 150 ppm or less.
(However, P4 is phosphorus detected as pyrophosphoric acid represented by the following structural formula (formula 1) when the partial aromatic polyamide is dissolved in a ³¹ P-NMR measurement solvent and trifluoroacetic acid is added, followed by structural analysis. (The phosphorus atom content derived from the compound.)

The polyamide composition according to claim 1, wherein the phosphorus atom content (Px) obtained by the formula (1) in the partially aromatic polyamide is 100 ppm or less.
Px = PC- (P1 + P2 + P3 + P4) (1)
(Wherein PC is the total residual phosphorus atom content in the partially aromatic polyamide, and P1, P2, P3, and P4 are the structures after dissolving the partially aromatic polyamide in ³¹ P-NMR measurement solvent and adding trifluoroacetic acid, Phosphorus compound-derived phosphorus atom content detected as hypophosphorous acid when analyzed, phosphorus compound-derived phosphorus atom content detected as phosphorous acid, phosphorus compound-derived phosphorus atom content detected as phosphoric acid The amount of phosphorus atom derived from the phosphorus compound detected as pyrophosphate is shown in units of ppm) 2. The aliphatic polyamide is nylon 6, and the partially aromatic polyamide is a polyamide containing 50 mol% or more of structural units derived from metaxylylenediamine and adipic acid in the molecular chain. Or the polyamide composition in any one of 2. The polyamide composition according to any one of claims 1 to 3, further comprising a recovered product of the polyamide molded product from the polyamide composition. The polyamide composition according to any one of claims 1 to 4, wherein the moisture content is 200 to 2000 ppm. A molded article obtained by molding the polyamide composition according to any one of claims 1 to 5. The molded article according to claim 6 is a sheet-like product. The molded body according to claim 6, which is a stretched film obtained by stretching a sheet-like material in at least one direction.

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