JP2003165838A - Method for producing polyamide, and polyamide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a polyamide which has m- xylylenediamine as ≥70 mol% of a diamine component in a relatively short time so that the contents of insoluble and infusible materials is low, with a high polymerization degree and with which gelation can remarkably be suppressed and the gelation during processing and molding is scarcely caused. <P>SOLUTION: The polymerization is carried out by minimizing the moisture contents in a raw material (preferably using a diamine and a dicarboxylic acid in bulk) and suitably controlling the reaction conditions in each process of continuous production. The ratio (molar ratio) of amounts of carboxy end groups (CEG)/amino end groups (AEG) of the CEG and AEG of the polyamide is controlled to ≥1.2 in the latter polymerization process. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention has an excellent oxygen barrier property, and in particular, as a material for films, sheets, containers, packaging bags and the like which require an oxygen barrier property, and an oxygen barrier property such as polyethylene terephthalate. The present invention relates to a polyamide useful as a modifier which is blended with a polymer having poor oxygen content to impart an oxygen barrier property, and a method for producing the same.

[0002]

2. Description of the Related Art Various oxygen barrier materials have been developed for the purpose of suppressing changes in taste, flavor and efficacy due to oxygen in foods, beverages, pharmaceuticals, cosmetics, etc. and enabling long-term storage. And is used for films, sheets, containers, packaging bags, etc. As a conventionally known oxygen barrier material, for example, polyvinyl alcohol, polyvinylidene fluoride, polyvinylidene chloride, etc. are well known, but recently, a polyamide whose main diamine component is m-xylylenediamine (for example, Poly-m-xylylene adipamide, which is composed of m-xylylenediamine and adipic acid, has been attracting attention as a material having an excellent oxygen barrier property (see, for example, Patent Documents 1 and 2).

By the way, it is generally known that polyamide is easily gelled (see, for example, Patent Document 3), but among them, a polyamide whose main diamine component is m-xylylenediamine, particularly 70 diamine components. A polyamide in which mol% or more is m-xylylenediamine is very easy to gel. As a result, gelation occurs during the polymerization process, and the gelled product is deposited on the polymerization kettle to stain the polymerization kettle, which requires a lot of time and labor to clean the dirt. In addition, the gelled product generated in the polymerization process becomes an insoluble and infusible foreign substance, which mixes with the polyamide to be produced, which causes deterioration of the resin quality of the polyamide. Furthermore, when the manufactured polyamide is processed and molded, it is gelated by being placed under high temperature, which causes molding defects and deterioration of the quality (appearance and performance) of the molded product. .

[0004]

[Patent Document 1] Japanese Unexamined Patent Publication No. 2-500846

[Patent Document 2] Japanese Patent Laid-Open No. 3-762

[Patent Document 3] Japanese Patent Laid-Open No. 2000-72871

[0005]

SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to prevent the gelation of a polyamide in which 70 mol% or more of a diamine component is m-xylylenediamine in the polymerization process. It is an object of the present invention to provide a method for producing a polyamide, which has a high degree of polymerization and a low content of insoluble / infusible matter, and can be produced in a relatively short time so that gelation does not easily occur during its processing / molding. . Another object of the present invention is to provide a high-quality polyamide which has few foreign matters, is excellent in oxygen barrier property and processability / moldability, and can be obtained as a molded product excellent in appearance and performance.

[0006]

[Means for Solving the Problems] Gelation of a polyamide occurs when a polymer is three-dimensionalized by formation of a tertiary amide, and the tertiary amide is produced by deammonification reaction from terminal amino groups of two molecules (polymer chain). Brought to you by Immin. As a result of intensive studies by the present inventors, in the production of a polyamide in which a main diamine component is m-xylylenediamine, in order to suppress imine formation, the amount of water in a polymerization raw material (formulation of diamine and dicarboxylic acid) is adjusted. It is extremely effective to reduce the amount as much as possible, and further, by adopting a continuous production process, the supply amount ratio (molar ratio) of the diamine and the dicarboxylic acid to be supplied to the amidation step in the continuous production process is 1: 1 as much as possible. The gelation can be remarkably suppressed by controlling the amount of the terminal amino groups (hereinafter, also referred to as CEG) of the polyamide in the latter polymerization step in the continuous production process to significantly suppress gelation. A polyacetal obtained by adjusting the end group so that the amount thereof is larger than the amount of the group (hereinafter, also referred to as AEG). De hardly cause increase in molecular weight is also placed under high temperatures, thereby found that gelation at the time of processing and molding is effectively suppressed, and have completed the present invention.

That is, the present invention is as follows. (1) The dicarboxylic acid (C) and the diamine (A) are mixed so that the amount ratio C / A (molar ratio) is 0.975 to 1.025, and the mixture is supplied to the amidation step. By the continuous production process of increasing the degree of polymerization of the polymer produced by polycondensation in the polymerization step in the initial polymerization step and the latter polymerization step,
A method for producing a polyamide in which at least 70 mol% of a diamine component comprises m-xylylenediamine,
The water content in the formulation of dicarboxylic acid (C) and diamine (A) is less than 20% by weight, and the relative viscosity (Rv ₁ ) of the polymer formed in the amidation step is 1.2 to 1.8, the initial value. The relative viscosity (Rv ₂ ) of the polymer produced in the polymerization step is 1.4 to 2.1, and the increase in the degree of polymerization (ΔRv) from the initial polymerization step to the late polymerization step is 0.05 to 1.8, In addition, a terminal amino group modifier is added in the latter polymerization step so that the final carboxyl group (CE
G) and terminal amino group (AEG) amount ratio CEG / AEG
A method for producing a polyamide, which comprises adjusting the (molar ratio) to 1.2 or more. (2) The above-mentioned (1), wherein the terminal amino group modifier is an acid anhydride.
A method for producing the described polyamide. (3) A polyamide in which at least 70 mol% of the diamine component is m-xylylenediamine, the relative viscosity at 20 ° C. is 1.8 to 3.6, and the tertiary nitrogen content is 0.6.
A polyamide characterized by having a molar ratio CEG / AEG (molar ratio) of terminal carboxyl groups (CEG) and terminal amino groups (AEG) of not less than 5 mol% and not less than 1.2.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below. In the polyamide produced by the present invention, at least 70 mol% of the diamine component is m-xylylenediamine (hereinafter, MXD).
(Also referred to as). When MXD in the diamine component is less than 70 mol%, the oxygen barrier property is significantly reduced. The preferred amount of MXD is 75
It is at least mol%, particularly preferably at least 80 mol%. M
Examples of diamine components other than XD include ethylenediamine, 1,2-propylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine,
Aliphatic diamines such as decamethylenediamine, undecamethylenediamine and dodecamethylenediamine; alicyclic diamines such as cyclohexanediamine and bis (4-aminocyclohexyl) methane; aromatic diamines such as p-xylylenediamine Can be mentioned. Among these, ethylenediamine, 1,2-propylenediamine, hexamethylenediamine and p-xylylenediamine are preferable.
Diamine components other than MXD are 2 even if used alone.
One or more species may be used in combination at any ratio, and it is used within the range of less than 30 mol% in all diamine components.

Examples of the dicarboxylic acid component include fats such as adipic acid, sebacic acid, malonic acid, succinic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, undecanoic acid, undecadioic acid, dodecanedioic acid and dimer acid. Group dicarboxylic acids; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid; aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, xylylenedicarboxylic acid, and naphthalenedicarboxylic acid. Among these, adipic acid (hereinafter also referred to as AA), sebacic acid (hereinafter also referred to as SA), and isophthalic acid (hereinafter also referred to as IPA) are preferable. The dicarboxylic acid component may be used alone or in combination of two or more kinds at any ratio. When two or more kinds are used in combination, it is preferable to use any two kinds selected from AA, SA and IPA or three kinds thereof in combination.

In addition to the above-mentioned diamine component and dicarboxylic acid component, lactams such as ε-caprolactam and laurolactam; aminocarboxylic acids such as aminocaproic acid and aminoundecanoic acid may be used as a copolymerization component.

In the present invention, polyamide is produced by a continuous production process. The "continuous production process" in the present invention comprises a raw material blending step, an amidation step, an initial polymerization step and a late polymerization step, each step is carried out in an individual facility, and between these plural equipments, The process is a process in which the discharge from the equipment of the process of (1) is connected so as to be the supply to the equipment of the subsequent process, and from the raw material preparation to the production of the final product (the target polyamide) is continuously performed.

FIG. 1 is a schematic view of an example of an apparatus for carrying out a continuous manufacturing process. Hereinafter, each step (raw material mixing step, amidation step, initial polymerization step and late polymerization step) will be described in detail with reference to this figure.

Raw Material Mixing Step In this step, the dicarboxylic acid (C) and the diamine (A) are mixed so that the amount ratio C / A (molar ratio) is in the range of 0.975 to 1.025, and the next step Supply to the amidation process.
Amount ratio C / of dicarboxylic acid (C) and diamine (A)
When A (molar ratio) is out of this range, not only it becomes very difficult to control the polycondensation reaction of the polyamide, that is, the reaction control in the steps after the amidation step of the next step, but in some cases, the polyamide The degree of polymerization may not reach the target degree of polymerization. The amount ratio (C / A) of the dicarboxylic acid (C) and the diamine (A) is preferably 0.980 to 1.020 (molar ratio), more preferably 0.985 to 1.015 (molar ratio). .

In this step, generally, as shown in FIG. 1, the dicarboxylic acid and diamine are melted and stored in bulk by the respective melting / storage tanks 1 and 2 of dicarboxylic acid and diamine and the raw material supply pumps 3a and 3b. Supply to the process. Since the dicarboxylic acid is usually a solid, the dicarboxylic acid melting / storage tank 1 includes a melting tank 1a for melting the dicarboxylic acid,
Storage tank 1b for storing the molten material melted in the melting tank 1a
Composed of and. The melting and storage temperature of dicarboxylic acid is
[Melting point of dicarboxylic acid] to [melting point of dicarboxylic acid + 20 ° C]
It is appropriate to set the range to. When the melting / storage temperature is higher than the above range, the dicarboxylic acid may be thermally deteriorated or decomposed, which is not preferable. On the other hand, if the amount is lower than the above range, the mixture becomes non-uniformly melted, and the amount ratio of the dicarboxylic acid and the diamine in the formulation is largely deviated from 1: 1, which is not preferable.

The diamine melting / storage tank 2 is usually composed of a single tank. The melting / storing temperature of the diamine is appropriately in the range of [melting point of diamine] to [melting point of diamine + 20 ° C.]. If the melting / storage temperature is out of this range, it is not preferable for the same reason as the dicarboxylic acid. In addition, both the dicarboxylic acid and the diamine are preferably placed in an inert gas atmosphere, for example, a nitrogen atmosphere, for the purpose of suppressing thermal oxidative decomposition.

The raw material supply pumps 3a and 3b are means for quantitatively supplying the dicarboxylic acid and the diamine in the melting / storage tanks 1 and 2, respectively, and mixing them at a desired mixing ratio to supply to the next amidation step. There is no particular limitation, but a plunger pump is preferable.

The dicarboxylic acids and diamines in the melting / storage tanks 1 and 2 may be added with an alkali metal compound, a phosphorus compound or the like for the purpose of suppressing thermal oxidative decomposition of the polyamide or as a polycondensation catalyst. The alkali metal compound is a compound containing an alkali metal, for example,
Hypophosphorous acid and alkali metal salts of phosphorous acid (potassium salt,
Sodium salts, lithium salts, etc.) and their hydrates,
Alkali metal hydroxides (eg sodium hydroxide,
Potassium hydroxide, lithium hydroxide, etc.), sodium acetate, sodium acetate trihydrate, potassium acetate, lithium acetate dihydrate, etc., among which sodium hypophosphite and its hydrate, water Sodium oxide, potassium hydroxide and sodium acetate are preferred. These may be used alone or in combination of two or more. The addition amount of the alkali metal compound is preferably 0 to 600 ppm as a metal atom (alkali metal atom) with respect to the polyamide, and more preferably 0 to 500 ppm.

As the phosphorus compound, hypophosphorous acid,
Phosphorous acid, phosphoric acid and their Li, Na or K
Examples include salts; hypophosphorous acid, lower alcohol esters of phosphorous acid and methyl and ethyl of phosphoric acid, and the like. Among these, hypophosphorous acid; phosphorous acid; Li of hypophosphorous acid,
Na or K salt; Li, Na or K salt of phosphorous acid is preferred. The addition amount of the phosphorus compound is preferably 0 to 550 ppm as a P atom with respect to the polyamide, and more preferably 0 to 500 ppm.

In this step, as described above, the dicarboxylic acid melting / storing tank 1 and the diamine melting / storing tank 2 are used, and the dicarboxylic acid and the diamine are transferred to the amidation step in bulk (as a melt). It is preferable to supply it, but an aqueous solution containing a salt of dicarboxylic acid and diamine may be supplied to the amidation step. However, the amount of water in the aqueous solution must be less than 20% by weight. In the case of an embodiment in which an aqueous solution containing a salt of a dicarboxylic acid and a diamine is supplied to the amidation step, a storage tank storing an aqueous solution of diamine is used instead of the melting / storage tank 2 of diamine, or Instead of the melting / storage tank 1 and the diamine melting / storage tank 2, a storage tank storing an aqueous solution containing a salt of a dicarboxylic acid and a diamine is used.

In this step, a bulk preparation of dicarboxylic acid and diamine is supplied to the amidation step, or an aqueous solution containing a salt of dicarboxylic acid and diamine having a water content of less than 20% by weight is supplied to the amidation step. By doing so, it is possible to sufficiently suppress the production of imine in the polymerization step after the next amidation step.

In the present invention, the target degree of polymerization of polyamide (final degree of polymerization) is 2 when sulfuric acid is used as a solvent.
Relative viscosity at 0 ° C. is 1.8 to 3.6, preferably 1.9.
The degree of polymerization is ˜3.3. When the relative viscosity is less than 1.8, the mechanical strength of polyamide becomes low, and it is not suitable as a raw material for films, sheets and the like. When it exceeds 3.6, in order to obtain such a product, the following step is required. The polymerization time after the amidation step must be lengthened, which causes coloration and deterioration of the polymer. In addition, a polyamide having a relative viscosity of more than 3.6 easily causes gelation during processing and molding.

Amidation step In this step, a polymer having a low degree of polymerization is prepared by a polycondensation reaction from a diamine and a dicarboxylic acid, which are prepared in a predetermined amount ratio (mixing ratio) in the raw material mixing step and are continuously supplied. This is a process of generating.

As the equipment used in this step, a pipe reactor, a static mixer, a continuous vertical stirring tank system and the like can be used, but a pipe reactor is preferable, and the pipe reactor 4 is shown in FIG. The advantage of using the pipe reactor is that the structure does not require liquid level control, the pressure resistance is excellent, and the facility cost is low. In this amidation step, the relative viscosity (Rv
A polymer having ₁ ) of 1.2 to 1.8 is obtained. That is, the relative viscosity (Rv ₁ ) of the polymer in the product discharged from the equipment for performing this step (amidation) (the product supplied to the equipment for performing the initial polymerization step of the next step) is 1.2 to The reaction is performed so as to be 1.8. When the relative viscosity (Rv ₁ ) is less than 1.2, the degree of polymerization is too small, and in order to obtain a polyamide having a desired degree of polymerization, the burden on the subsequent initial polymerization step becomes large. That is, the amount of water generated in the initial polymerization step increases, causing problems such as bumping and clogging of a water distilling can, and an increase in residence time and a decrease in productivity. On the other hand, when the relative viscosity (Rv ₁ ) exceeds 1.8, the melt viscosity of the reaction product becomes high, and uneven flow occurs in the reaction equipment to cause a variation in the degree of polymerization, thereby producing a polyamide of stable quality. Becomes difficult. In the present invention, the relative viscosity (Rv ₁ ) is preferably in the range of 1.30 to 1.75,
The range is more preferably 1.35 to 1.70.

The degree of polymerization of the polymer produced in this step is controlled by adjusting the temperature, pressure and residence time in the equipment. The residence time is the time during which the polymer is present in the facility, and the residence time is controlled by adjusting the size of the facility and the amount of raw material supplied.For example, in the case of a pipe reactor, the size of the pipe ( It is performed by adjusting the pipe diameter, the pipe length) and / or the raw material supply amount. Here, the equipment internal temperature is preferably about 110 to 300 ° C., the internal pressure is preferably about 0 to 1 MPa, and the residence time is preferably about 5 to 120 minutes. As more preferable conditions, the equipment internal temperature is 120 to 290 ° C (particularly preferably 130 to 280 ° C), and the internal pressure is 0 to 0.9MP.
a (particularly preferably 0 to 0.8 MPa), residence time is 10 to 110 minutes (particularly preferably 15 to 100)
Minutes).

Initial polymerization step In this step, the condensed water in the polymer produced in the amidation step, which is supplied from the amidation step, and the water solvent when an aqueous solution containing a salt of dicarboxylic acid and diamine is used, are used. It is a step of increasing the polymerization degree of the polymer by distilling off. As the equipment used in this step, a vertical stirring tank, a centrifugal thin film evaporator, or the like can be used, but the vertical stirring tank is preferable from the viewpoint of easy control of reaction conditions. FIG. 1 shows a vertical stirring tank 5. The polymer having a low degree of polymerization supplied from the amidation step has a relative viscosity (Rv ₂ ) of 1.4 to
The degree of polymerization is increased to a range of 2.1. That is, the relative viscosity (Rv ₂ ) of the polymer in the product discharged from the above reaction equipment (tank) (the product supplied to the equipment for performing the subsequent polymerization step in the next step) is 1.4 to 2.1. The reaction is performed as follows. The relative viscosity (Rv ₂ ) is 1.4
If it is less than the above range, the degree of polymerization is too low, and the load in the next step increases. If it is larger than 2.1, the residence time in the reaction equipment (tank) becomes too long to obtain such a product,
Gelation and thermal deterioration are likely to occur.

The lower limit of the relative viscosity (Rv ₂ ) is preferably 1.60 or more, more preferably 1.7.
It is 5 or more, particularly preferably 1.80 or more, and the upper limit thereof is preferably 2.07 or less, more preferably 2.03 or less. The degree of polymerization is controlled by the equipment temperature,
It is performed by adjusting the pressure, residence time, etc., and the temperature inside the equipment is [melting point of polyamide] to [melting point of polyamide + 4
0 ° C.], the internal pressure is 0 to 1 MPa, and the residence time is 10
It is preferably 150 minutes. The residence time here is the time during which the polymer exists in the equipment (time from input to discharge)
Is. More preferable reaction conditions are that the temperature inside the equipment is [melting point of polyamide] to [melting point of polyamide + 35 ° C] (particularly preferably [melting point of polyamide] to [melting point of polyamide +
30 ° C]), the internal pressure is 0 to 0.9 MPa (particularly preferably 0 to 0.8 MPa), and the residence time is 15 to 140 minutes (particularly preferably 15 to 130 minutes).

Late Polymerization Step In this step, the degree of polymerization of the polymer produced in the initial polymerization step, which is supplied from the initial polymerization step, is finally increased to a target degree of polymerization (that is, it is produced in the initial polymerization step). Yielding a polymer that is more highly polymerized than the polymer), and
By adding a terminal amino group modifier, the final product polyamide has carboxyl terminal groups (CEG) and terminal amino groups (AE).
This is a step of adjusting the amount ratio CEG / AEG (molar ratio) of G) to 1.2 or more. As equipment used in this process,
A kneading machine such as a twin-screw ruder or a single-screw ruder can be used, but the twin-screw ruder is preferable because of its excellent kneading effect and easy control of reaction and adjustment of end groups. FIG. 1 shows a biaxial ruder 6. A kneader equipped with a vacuum vent is used.

In this step, it is important to increase the degree of polymerization of the polymer supplied from the initial polymerization step within the range where the increase in relative viscosity (ΔRv) is 1.8 or less. Here, the increment of relative viscosity (ΔRv) means [relative viscosity of polymer discharged from reaction equipment (kneader) for performing the step (Rv ₃ )]-[polymer produced in the initial polymerization step] Relative viscosity (Rv ₂ )]. When the increase ΔRv in the relative viscosity is larger than 1.8, gelation is not sufficiently suppressed. That is, a rapid increase in viscosity causes gelation even with a small amount of imine. In this step, since the kneading time is required so that the terminal amino group modifier can sufficiently react with the terminal amino group, ΔR
It is important that the lower limit of v be 0.05 or more.

The terminal amino group modifier (hereinafter, also referred to as AEG modifier) is supplied, for example, in a fixed amount from a feeder attached to a kneader. The supply can be performed at any time from the time when the reactant is supplied to the kneader to the vacuum vent. The AEG modifier can be used without particular limitation as long as it is a compound capable of reacting with an amino group, and examples thereof include acid anhydrides, aliphatic or aromatic carboxylic acids, and epoxy compounds. Above all, the use of an acid anhydride is preferable from the viewpoints of good reactivity with an amino group, generation of CEG by the reaction, and environmental hygiene. As the acid anhydride, for example, acetic anhydride,
Examples thereof include succinic anhydride, maleic anhydride, hexahydrophthalic anhydride, phthalic anhydride, trimellitic anhydride, pyromellitic dianhydride, and among them, succinic anhydride, hexahydrophthalic anhydride, trimellitic anhydride, phthalic anhydride. Is preferred.

The amount of AEG modifier used is the desired CEG /
It is arbitrarily selected according to the AEG and the AEG amount. However, the use of a large excess is not only harmful to the polyamide because the AEG modifier remains unreacted, but
It is not preferable because it increases the cost. Specifically, in the case of an acid anhydride, it is usually 0.5 to 3.0 times equivalent to the amount of AEG present in the polyamide, preferably 0.8 to 3.0, depending on its volatility and reactivity. 2.5 times equivalent, particularly preferably 0.9 to 2.0 times equivalent.

In this step, CEG / A of polyamide is used.
By setting EG to 1.2 or more, it is possible to produce a polyamide that is extremely unlikely to gel during processing and molding. This is because polyamide has a higher degree of polymerization (viscosity) (becomes a higher molecular weight) and is prone to gelation when placed at a high temperature during molding and processing, but CEG / AEG is 1.2 or more. By doing so, such an increase in the degree of polymerization (viscosity) can be suppressed, and thus gelation is suppressed. The CEG / AEG is preferably 1.3 or more, more preferably 1.5 or more. The upper limit of CEG / AEG is not particularly limited, but is preferably 50 or less from the viewpoint of the reactivity between AEG and the AEG modifier within a short residence time.

Further, the AEG amount of the polyamide after CEG / AEG adjustment is 70 meq from the viewpoint of suppressing thermal oxidative decomposition.
/ Kg or less, preferably 35 meq / kg or less, and particularly preferably 30 meq / kg or less. That is,
The smaller the AEG amount, the more preferable. The amount of CEG is
Although not particularly limited, it is generally 80 to 200 meq /
It is about kg.

The kneading conditions (resin temperature, residence time, vent vacuum degree, etc.) in this step are such that the final degree of polymerization of the desired polyamide (as described above, sulfuric acid is used as a solvent at 20 ° C.).
The relative viscosity at is in the range of 1.8 to 3.6. ) And C
Although different depending on EG / AEG, the resin temperature is preferably [polyamide melting point] to [polyamide melting point + 40 ° C], more preferably [polyamide melting point] to [polyamide melting point + 45 ° C], and the vent vacuum degree is 1-750h
Pa is preferable, more preferably 1 to 700 hPa, and the residence time is preferably 1 to 30 minutes, more preferably 1.5 to 25 minutes, and particularly preferably 2 to 20 minutes.

The final CEG / AE of polyamide
In order to adjust G, a method of breaking the molar balance of diamine and dicarboxylic acid in the polymerization raw material, or adding a monofunctional compound (end group modifier) having reactivity with diamine or dicarboxylic acid is conceivable. If such a method is adopted, the polycondensation reaction is delayed, and it becomes difficult to increase the polymerization degree of the polyamide to a target polymerization degree.

In the production method of the present invention, a diamine, particularly,
The formation of imines from the terminal amino groups of two molecules of m-xylylenediamine can be sufficiently suppressed, and the three-dimensionalization (gelation) of the polymer due to the formation of tertiary amides can be sufficiently suppressed, so that at least 70 parts of the diamine component can be obtained. A polyamide having a mol% of m-xylylenediamine can be produced in a relatively high time with a sufficiently high degree of polymerization. The polyamide of the present invention thus produced has an excellent oxygen barrier property and a sufficiently high degree of polymerization (relative viscosity of 1.8 to 3.
6) and a small amount of foreign matter, and a tertiary nitrogen content of 0.65 mol% or less and a CEG / value of 1.2 or more.
Since it has AEG, it is extremely unlikely to cause gelation during processing and molding, and a polyamide capable of obtaining a high-quality molded product excellent in appearance and performance. Here, the “tertiary nitrogen content” is the ratio (molar ratio) of the nitrogen of the tertiary amide (bond) to the nitrogen of the secondary amide (bond) in the polyamide.

[0036]

EXAMPLES Examples and comparative examples of the present invention will be described below,
The present invention will be described more specifically. The analysis and measurement in Examples and Comparative Examples were performed by the following methods.

[Measurement of Tertiary Nitrogen Content] A sample was dissolved in hexafluoroisopropanol (HFIP), and carbon ₁₃ was measured using a Unity-500 NMR spectrometer manufactured by Varian.
The spectrum of (C ¹³ ) was analyzed to measure the tertiary nitrogen content (molar ratio (mol%) to nitrogen based on secondary amide).

[Measurement of Amount of Terminal Carboxyl Group (CEG)] To 0.2 g of the sample, 10 ml of benzyl alcohol was added and dissolved at 180 ± 5 ° C. for 5 minutes. This solution was cooled in water for 15 seconds, and phenolphthalein was used as an indicator for ethanolic potassium hydroxide solution (0.5N).
Ethanol was added to 80 ml of -KOH to adjust to 1000 ml), and titration was performed, and the value was calculated by the following formula. CEG (meq / kg) = {[(A-B) x N x f]
/ (W × 1000)} × 10 ⁶ A: titer (ml) B: blank titer of dissolution (ml) N: concentration of ethanolic potassium hydroxide (mol / l) f: factor of ethanolic potassium hydroxide w: sample weight (g)

[Measurement of Amount of Terminal Amino Group (AEG)] 0.6 g of a sample was mixed with 5 parts of phenol / ethanol (volume ratio 4/1).
0 ml, then water / ethanol (volume ratio 3 /
2) 20 ml was added and one drop of the indicator methyl orange was added. Aqueous ethanolic hydrochloric acid solution (1 / 10N HCl to 1
Distilled water is added to 00 ml and 50 ml of ethanol to obtain 500
Prepared to ml. ), And calculated by the following formula. The valence of the transition metal was subtracted as a blank. AEG (meq / kg) = {[(A−B) × N × f] /
(W × 1000)} × 10 ⁶ A: titer (ml) B: blank titer of solvent (ml) N: concentration of ethanolic HCl (mol / l) f: factor of ethanolic HCl w: sample weight ( g)

[Measurement of Relative Viscosity] 0.25 g of polyamide
Was dissolved in 25 ml of 96.3% sulfuric acid to obtain 10 m of this solution.
1 was measured with an Ostwald viscous tube at 20 ° C. and calculated from the following formula. Rv = t / t ₀ t ₀ : Second of dropping solvent t: Second of dropping sample solution

Final polymer (polymer after the latter polymerization step)
The relative viscosity (Rv ₃ ) of was measured using a chip after the latter polymerization step. Relative viscosity of polymer after amidation step (R
v ₁ ) was measured for the sample sampled by the sampling valve provided in the transfer line from the amidation step to the initial polymerization step. The relative viscosity (Rv ₂ ) of the polymer after the initial polymerization step was measured for the sample sampled by the sampling valve provided in the transfer line from the initial polymerization step to the late polymerization step.

[Measurement of Oxygen Permeability Coefficient] JIS K 71
According to No. 26, it was measured under the conditions of 24 ° C. and 100% RH. The oxygen permeability coefficient means that the smaller the value, the more difficult it is for oxygen to permeate, and the excellent long-term storage stability of foods, beverages, pharmaceuticals, cosmetics and the like will be excellent. In the present invention, the desirable oxygen permeability coefficient is 5 or less, and more desirably 4 or less.

[Gelization time] The gelation time is the time required for the heated sample to gel, and the larger this value is, the more difficult it is to gel and the less insoluble / infusible foreign matter. Means 3 g of a sample (polyamide) dried under reduced pressure at 100 ° C. for 24 hours was put into a branched test tube having an internal capacity of about 20 ml, and the pressure was reduced to 3 times, and then 30 times.
It was immersed in an oil bath at a constant temperature of 260 ° C. and heated for a predetermined time while flowing a nitrogen gas of ml / min. Then, 0.25 g of the heat-treated sample is added to 25 ml of 96% sulfuric acid.
When it was dissolved at room temperature for 16 hours, the time required to visually recognize the insoluble matter was measured. In the present invention, the longer the gelation time is, the more desirable it is, but 12 hours or more is desirable, and 13 hours or more is particularly desirable.

[Viscosity increase index (ΔRg)] The viscosity increase index (ΔRg) is an index of viscosity variation of polyamide with time, and is defined by the following formula. ΔRg = [(relative viscosity 1 hour before gelation (Rvt))-(relative viscosity before gelation treatment (Rvb))] / (time required from the start of gelation treatment to 1 hour before gelation) Both the relative viscosities (Rvt) and (Rvb) of were measured by the above relative viscosity measuring method. Further, the reason why the relative viscosity before gelation is adopted is that the relative viscosity at the time of gelation changes because the sample becomes insoluble. If the index of increase in viscosity (ΔRg) is small, the increase in viscosity during processing / molding is small, the processability / moldability is excellent, and gelation is difficult, and the index is preferably 0.15 or less. , 0.13 or less is particularly preferable.

Production Example of Polyamide In the following description and table, AA is adipic acid, S
A is sebacic acid, IPA is isophthalic acid, MXD is m-
Xylylenediamine, HMDA is hexamethylenediamine, SCA is succinic acid-free, OPA is phthalic anhydride, H-
OPA is hexahydrophthalic anhydride, TMA is trimellitic acid, and CLM is ε-caprolactam.

Example 1 (Polyamide A) Using the production equipment shown in FIG. 1, a polyamide was produced in the following procedure by a continuous production process including a raw material mixing step, an amidation step, an initial polymerization step and a late polymerization step. A was produced. 17
Molten AA containing 0.105% by weight sodium acetate and 0.21% by weight sodium hypophosphite in AA melted at 0 ° C. and heated to 60 ° C. with molten AA containing sodium acetate and sodium hypophosphite. MXD and Plunger pump respectively, for AA 4.766kg / h
The amount of r supplied is 4.428 kg / hr for MXD.
Was continuously supplied to the pipe reactor having a pipe diameter of 20 A and a pipe length of 13.5 m for the amidation step. In the amidation step, the pipe reactor jacket temperature was 300 ° C., the internal pressure was 0.15 MPa, and the residence time was 30 minutes. During this time, the temperature of the contents is 170 ℃
Raised to ~ 245 ° C. The low polymer produced in the amidation step was continuously supplied to the vertical stirring tank for the initial polymerization step. In the initial polymerization step, the internal temperature of the vertical stirring tank was 265 ° C,
The internal pressure was set to 0.15 MPa, the feed from the amidation step was retained for 60 minutes to increase the degree of polymerization. The polymer that has been subjected to the initial polymerization process has a resin temperature of 265 for the latter polymerization process.
℃, vent vacuum degree 530 hPa, screw rotation speed 15
TEM-37B manufactured by Toshiba Machine Co., Ltd. controlled at 0 rpm
A fixed amount was supplied to the S biaxial ruder. The adjustment of CEG / AEG was performed by quantitatively supplying an acid anhydride compound (hexahydrophthalic anhydride) with a feeder 4 minutes after the start of supplying the polymer to the biaxial ruder. The residence time in the biaxial ruder was about 6 minutes. The obtained polyamide was discharged in water in a strand form and cut into chips. This is polyamide A. Table 1 shows the type of raw material, composition (C / A, water content), and physical properties of the polymer (amount of terminal group, CEG / AEG, relative viscosity, tertiary nitrogen content). In addition, Table 2 shows the production conditions (temperature, pressure, residence time) in the amidation step, the initial polymerization step and the late polymerization step. The residence time in the amidation step is
It was determined from the relationship between the volume in the pipe reactor and the supply amount, and the residence time in the initial polymerization step was determined from the relationship between the low polymer amount in the vertical stirrer and the discharge amount. Regarding the residence time in the latter-stage polymerization step, polyethylene and a color pigment (carbon black) were used in advance, and the relationship between the number of revolutions of the biaxial ruder and the polymer supply amount and the residence time was grasped and applied.

Comparative Example 1 (polyamide B), Example 5
(Polyamide I), Comparative Example 1 (Polyamide J), Example 8 (Polyamide N), Comparative Example 7 (Polyamide O), Example 9 (Polyamide P)]
Polyamide B obtained by polymerizing the raw materials shown in Table 1 under the conditions shown in Table 2 by a continuous manufacturing process using the manufacturing equipment of
I, J, N, O, P were obtained. Polyamides I, J,
In the production of N, O and P, the residence time in the amidation process, the initial polymerization process and the latter polymerization process is
The same was applied to the above, but for polyamide B not subjected to CEG / AEG adjustment, the residence time in the latter polymerization step was set to 5 minutes.

Example 2 (Polyamide C), Example 3
(Polyamide D), Example 6 (Polyamide L)] As in the case of the polyamide A, the raw materials shown in Table 1 were polymerized under the conditions shown in Table 2 by the continuous production process using the production equipment shown in FIG. C, D and L were obtained. The residence time in the amidation step and the initial polymerization step was 35 each.
Changed to 70 minutes.

[Comparative Example 2 (Polyamide E), Comparative Example 3
(Polyamide F)] The polyamide E and F were obtained by polymerizing the raw materials shown in Table 1 under the conditions shown in Table 2 by the continuous production process using the production equipment shown in FIG. The residence times in the amidation step, the initial polymerization step and the late polymerization step were extended to 60 minutes, 90 minutes and 8 minutes, respectively, but the degree of polymerization of the polymer was low and the desired degree of polymerization (relative viscosity 1.8 to 3). .6) was not reached.

Example 4 (Polyamide G), Example 7
(Polyamide M)] As in the case of the polyamide A, the raw materials shown in Table 1 are polymerized under the conditions shown in Table 2 by the continuous production process using the production equipment shown in FIG.
M was obtained. Polyamide G was used in the raw material mixing step to supply the molten AA containing sodium acetate and sodium hypophosphite to the pipe reactor by the plunger pump at 4.766 kg / hr, while the 81.3 wt% MXD aqueous solution was used. And the amount of supply to the pipe reactor by the plunger pump was 5.448 kg / hr.
And the residence times in the amidation step and the initial polymerization step were 40 minutes and 70 minutes, respectively. Polyamide M uses a mixture of AA and IPA containing sodium acetate and sodium hypophosphite in the raw material preparation step, and the amount of this supplied to the pipe reactor by the plunger pump is 4.8.
96 kg / hr, the amount of the 72.9 wt% MXD aqueous solution supplied to the pipe reactor by the plunger pump was 6.070 kg / hr, and the residence times of the amidation step and the initial polymerization step were 40 minutes and 75 minutes, respectively. did.

[Comparative Example 4 (Polyamide H), Comparative Example 6
(Polyamide K), Comparative Example 8 (Polyamide Q)] 14614 parts of AA, 13619 parts of MXD, in a pressure type reaction kettle,
14.96 parts of sodium acetate, 30.94 parts of sodium hypophosphite and 23100 parts of water were charged, and the atmosphere in the kettle was sufficiently replaced with nitrogen. The reaction vessel was sealed and the jacket temperature was raised to 275 ° C. in 45 minutes. The reaction was continued while the pressure inside the kettle was adjusted to 1 MPa to remove water. The reaction temperature increased with the distillation of water and reached 240 ° C. in 270 minutes from the start of temperature increase. At this point, pressure release was started and the pressure was adjusted to normal pressure for 60 minutes.
During this time, the reaction temperature rose to 260 ° C. After continuing the reaction for 60 minutes at the same temperature, the content was discharged in strands into water to obtain a polyamide. For this polyamide, use the biaxial ruder used in the production of polyamide A,
EG / AEG was adjusted. That is, acid anhydride (phthalic anhydride) is uniformly mixed with polyamide and dried under reduced pressure to obtain a resin temperature of 260 ° C. and a screw rotation speed of 100 rp.
m, vent vacuum degree was 200 hPa. This is designated as polyamide H. Polyamides K and Q were obtained according to the method for producing polyamide H above, except that the types of dicarboxylic acid and diamine and the water content in the raw materials were changed as shown in Table 1.

[Comparative Example 9 (Polyamide R)] Polyamide R was produced by the following procedure by a continuous production process using the production equipment shown in FIG. 14.73 in compounding can
8 g water, 17.800 g AA, 16.588 g M
XD, 31.8 g of sodium acetate and 21.3 g of sodium hypophosphite were added, and a 70 wt% AA-MXD salt aqueous solution was prepared under stirring at 0.22 MPa and 135 ° C. This AA-MXD salt aqueous solution was supplied at a flow rate of 8.12 L / hour into a pipe reactor controlled at a jacket temperature of 300 ° C. and an internal pressure of 3.5 MPa by a plunger pump. The residence time in the pipe reactor was 35 minutes, during which the temperature of the contents rose to 240 ° C. The low polymer produced in the amidation process has an internal temperature of 285 ° C and 3.5MP.
It was allowed to stay for 60 minutes in the initial polymerization step controlled to a, and the water and condensed water used as the solvent were distilled off to obtain a high polymer, and the resin temperature was controlled at 300 ° C., the vent vacuum degree was 500 hPa, and the screw rotation speed was 150 rpm. A fixed amount was supplied to the biaxial ruder. 4.5 minutes after the start of supplying the polymer to the biaxial ruder, hexahydrophthalic anhydride was quantitatively supplied to adjust CEG / AEG. The residence time in the twin-screw rudder was about 6.5 minutes.

Example 10 (Polyamide S) The pressure (internal pressure) in the amidation step and initial polymerization step was 0.70.
Polyamide S was produced in the same manner as in Example 1 except that the pressure was changed to MPa. In addition, in the amidation step, the temperature of the contents of the pipe reactor rose to 170 ° C to 246 ° C.

[0054]

[Table 1]

[0055]

[Table 2]

Table 3 shows the gelling time, viscosity increase index (ΔRg), and oxygen permeability coefficient of the polyamides A to R produced above. The * in the table means the measurement limit.

[0057]

[Table 3]

[0058]

As is apparent from the above description, according to the present invention, a polyamide in which 70 mol% or more of the diamine component is m-xylylenediamine is used, which has a high degree of polymerization and an insoluble or infusible content. It is possible to manufacture in a relatively short time by significantly suppressing gelation so that gelation hardly occurs at the time of processing and molding.
The polyamide thus obtained is a high-quality polyamide that has excellent oxygen barrier properties, processability and moldability, and that can be used to obtain a molded product with excellent appearance and performance.

[Brief description of drawings]

FIG. 1 is a schematic view of an example of an apparatus for carrying out a continuous manufacturing process according to the present invention.

[Explanation of symbols]

1, 2 melting / storage tank 3a, 3b Raw material supply pump 4 pipe reactor 5 Vertical stirring tank 6 biaxial ruder

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hidekazu Yoshida             2-8 Dojimahama 2-chome, Kita-ku, Osaka City, Osaka Prefecture             Toyobo Co., Ltd. (72) Inventor Kenta Suzuki             Toyobo Co., Ltd. 10-24 Toyocho, Tsuruga City, Fukui Prefecture             Expression company Polymer Development Center F-term (reference) 4J001 DA01 DB01 DB04 DC14 DD07                       DD13 EA06 EA08 EA14 EA16                       EB04 EB05 EB06 EB07 EB08                       EB09 EB14 EB34 EB35 EB36                       EB37 EB46 EB71 EC04 EC05                       EC06 EC07 EC08 EC09 EC14                       EC16 EC44 EC48 EE09D                       EE16D EE27C EE27D EE75D                       EE76D FA01 FA03 FB03                       FB06 FC03 FC06 FD01 GA12                       GB11 GB16 GE16 JA12 JB02                       JB29

Claims (3)

[Claims] 1. A dicarboxylic acid (C) and a diamine (A).
And the amount ratio C / A (molar ratio) is 0.975 to 1.0.
It is prepared to be 25 to be supplied to the amidation step, and the polymer produced by polycondensation in the amidation step is subjected to a continuous production process in which the degree of polymerization is increased in the initial polymerization step and the late polymerization step. A method for producing a polyamide comprising at least 70 mol% of m-xylylenediamine, wherein the water content of the mixture of dicarboxylic acid (C) and diamine (A) is less than 20% by weight, The relative viscosity (Rv ₁ ) of the polymer produced is 1.2 to 1.8, the relative viscosity (Rv ₂ ) of the polymer produced in the initial polymerization step is 1.4 to 2.1, and the initial polymerization step to the late polymerization The increase (ΔRv) in the degree of polymerization in the process is 0.
05-1.8, and a terminal amino group modifier is added in the latter polymerization step, and the final polyamide terminal carboxyl group (CEG) and terminal amino group (AEG) amount ratio CEG / AEG (mol Ratio) to 1.2 or more. 2. The method for producing a polyamide according to claim 1, wherein the terminal amino group modifier is an acid anhydride. 3. A polyamide comprising at least 70 mol% of a diamine component consisting of m-xylylenediamine,
Relative viscosity at 20 ° C. is 1.8 to 3.6, tertiary nitrogen content is 0.65 mol% or less, terminal carboxyl group (CEG)
And a terminal amino group (AEG) amount ratio CEG / AEG (molar ratio) is 1.2 or more.