JPH08176298A - High-melting polyamide and preparation thereof - Google Patents

Abstract

PURPOSE: To obtain a high-melting polyamide having a freedom from thermal deterioration, a good color tone and excellent mechanical properties by effecting melt extrusion polymn. of a lower condensate yet to become a specific high- melting polyamide while using a specific twin-screw extruder. CONSTITUTION: In preparing a high-melting polyamide by polymerizing a lower condensate of 1.1 to 1.5 in relative viscosity yet to become the high-melting polyamide while using an extruder, a twin-screw extruder having an L/D ratio of at least 33 and a degree of engagement of screws of at least 1.4 and equipped with a vacuum vent port is used as the extruder to effect melt extrusion polymn. of the lower condensate under a reduced pressure of at most 700Torr. The resulting polymer is not discolored through thermal deterioration and has a relative viscosity of 2.2 to 3.5. According to the method, there can be stably and efficiently obtd. a high-melting polyamide having a melting temp. close to the decomposition temp. thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high melting point polyamide which has a small heat history during polymerization and is therefore not colored by heat deterioration, and a method for producing the same. More specifically, the present invention relates to a high melting point polyamide excellent in mechanical properties such as color tone, heat resistance and abrasion resistance, impact resistance and mechanical strength, and a method for producing the same by melt extrusion polymerization.

[0002]

2. Description of the Related Art Polyamide has excellent abrasion resistance, impact resistance, moldability, chemical resistance and mechanical strength, and has been used in a wide range of fields such as automobile parts and electronic device parts. Although used, in recent years, resins having higher heat resistance have been required for higher performance of automobiles and electric / electronic parts. Therefore, in order to obtain higher heat resistance and rigidity, it has been attempted to increase the melting point by copolymerizing polyamide with an aromatic component. However, in that case, the decomposition temperature and the melting point of the polyamide resin are close to each other, which makes it difficult to carry out melt polymerization and causes a problem that the obtained polyamide resin is colored. Therefore, an effective manufacturing method for solving these problems is being sought.

For example, Japanese Patent Application Laid-Open No. 4-50230 proposes a method for producing a high-melting polyamide by melt polymerization using an extruder. In this proposal, an extruder is used as a reaction vessel for melt polymerization. However,
Since the polymerization is carried out under normal pressure, the polymerization rate is slow and it is necessary to prolong the residence time in the extruder, which causes deterioration of the resin. Further, the throughput of the extruder is reduced, which is a practical problem.

Further, in the method for producing a high melting point polyamide resin disclosed in JP-A-4-53825, JP-A-4-53826, JP-A-4-53827, etc., [NH ₂ ] rich or [COOH] is used. ] A method for producing a rich low-order condensate and then adding a deficient dicarboxylic acid component or diamine component to the low-order condensate to perform melt polymerization is used to control polymerization. Since the time is short, when the monomers such as the dicarboxylic acid component and the diamine component are added during the polymerization, the molecular weight distribution of the polymer is broadened, the content of low molecular weight substances is increased, and the physical properties of the finally obtained polymer are improved. Also has an adverse effect.

Further, regarding the melt polymerization in the extruder, in order to stabilize the polymerization state, an inorganic phosphate compound, etc.,
Methods for adding various additives have been proposed (JP-A-3-296528, JP-A-3-296529, JP-A-4-87730 and JP-A-5-436).
No. 81, etc.), these methods can improve the polymerization state, but they are not a fundamental solution and the physical properties of the polymer are adversely affected particularly by mixing the additive with the polymer.

[0006]

As described above, the conventionally known method for producing a high-melting-point polyamide by melt-polymerizing a low-order condensate using an extruder is not suitable for mechanical properties such as heat resistance and rigidity. However, it was not always a practical method for producing a high-melting point polyamide in terms of color tone. An object of the present invention is to solve the above-mentioned problems and to obtain a high melting point polyamide having a melting temperature and a decomposition temperature close to each other by melt extrusion polymerization using an extruder under specific conditions, thereby shortening the heat history at high temperature. However, it provides a high melting point polyamide polymer excellent in color tone and mechanical properties that could not be obtained conventionally, and also
It is to provide a method for producing such a polymer.

[0007]

Generally, screw type extruders include single-screw, twin-screw and multi-screw extruders. Also,
Among the twin-screw extruders, the screw structure is 1
There are threads with double threads, double threads and triple threads. Further, the screw groove is classified into a shallow groove type and a deep groove type depending on the groove depth. In general, the shallow groove has a meshing ratio in the range of 1.2 to 1.35, and the deep groove has a mesh ratio of 1.4 to 2.4.
Stipulated as being in the range of.

The present inventors diligently studied melt polymerization using an extruder, especially the screw type extruder. As a result, in producing the high melting point polyamide by melt polymerization, an extruder having a twin screw, double thread screw, deep groove structure and L / D of 33 or more is used among the above extruders, and a vacuum vent is used for the extruder. By reducing the pressure by adding a port, and further by effectively reducing the pressure by making the screw constitution of the conveying element, the kneading element and the seal ring element having a draw ratio of 5 to 30%, the polymerization It has been found that a polymer without coloring can be obtained by minimizing the thermal deterioration at the time, and that the polymer has dramatically high mechanical properties in correlation with the decrease in the degree of coloring. Reached

That is, the present invention has a relative viscosity of 1.1 to
When the low-order condensate of high melting point polyamide of 1.5 is polymerized by an extruder to produce the high melting point polyamide, L
/ D is 33 or more, the structure of the screw is a double thread screw, the engagement rate is 1.4 or more, and a twin-screw extruder having a decompression vent port is used, and preferably the screw configuration is a conveying element, a kneading element and Aperture ratio is 5
Using a twin-screw extruder consisting of -30% seal ring element, under a reduced pressure condition of 700 Torr or less, relative viscosity of 2.2-3.5, not subjected to thermal deterioration, 1 g / dl Dissolved in formic acid at a concentration of 1%, the solution has a transmittance of 80% or more for light having a thickness of 1 cm and a wavelength of 330 nm, and is dissolved in 98% sulfuric acid at a concentration of 1 g / dl,
The solution has a transmittance of 80% or more for light having a thickness of 1 cm and a wavelength of 350 nm, and the Y of the pellet is also
It can be achieved by providing a high melting point polyamide polymer having an I value of 20 or less, and a method for producing the polymer.

The method of the present invention will be described in detail below.
The resin targeted by the present invention is a high melting point polyamide resin having a melting point of 270 ° C. or higher, and its thermal decomposition temperature and melting temperature are close to each other. It is a polyamide resin that cannot be obtained. That is, such a polyamide resin has a too high melt viscosity in a usual melt polymerization method and cannot be discharged,
Since the melting point of the polymer resin is close to the thermal decomposition temperature of the polymer resin, the polymer resin is decomposed or deteriorated during melt polymerization. The resin thus deteriorated is colored and cannot exhibit the original mechanical properties, and particularly the tensile elongation and impact strength are lowered.

Suitable examples of such a polyamide resin include semi-aromatic polyamide and nylon 46. And as a semi-aromatic polyamide, nylon 6T (T: terephthalic acid component, the same applies below)
And nylon 6T, nylon 6, nylon 66,
One or more polyamide homopolymers selected from nylon 11, nylon 12, nylon M6 (M: metaxylylenediamine component, the same below), nylon 6I (I: isophthalic acid component, the same below), etc. Specific examples thereof include copolymers with.

A polymer produced by the method of the present invention,
That is, although the above-mentioned high melting point polyamide resin is not particularly limited in the degree of polymerization, it is usually 25 ° C of a 1% sulfuric acid solution.
It is necessary that the relative viscosity (ηr) in 2 satisfies 2.2 to 3.5. If the relative viscosity is less than 2.2,
It is not preferable because mechanical strength such as tensile strength and bending strength of the high melting point polyamide resin and mechanical properties such as impact resistance are deteriorated. Further, the relative viscosity is 3.
When it exceeds 5, it is not preferable because the high melting point polyamide resin becomes difficult to be formed by injection molding, extrusion molding, blow molding or the like into a final product.

In the method of the present invention, 25% of a 1% sulfuric acid solution of a low-order condensate for producing a high melting point polyamide.
The relative viscosity (ηr) in 1 needs to satisfy 1.1 to 1.5, and preferably in the range of 1.15 to 1.4. Relative viscosity (ηr) is 1.1
The use of a low-order condensate of ~ 1.5 facilitates handling and facilitates polymerization by melt polymerization in the extruder. That is, when the relative viscosity is lower than 1.1, when the low-order condensate is supplied to the extruder, the low-order condensate adheres to the raw material introduction port of the extruder, making it difficult to supply the low-order condensate. Or, rapid foaming of the resin occurs in the extruder and stable melt polymerization cannot be performed, which is not preferable. On the other hand, if the relative viscosity is larger than 1.5, the side reaction product contained in the low-order condensate deteriorates the physical properties of the high-melting polyamide obtained by polymerization in an extruder, which is not preferable. The relative viscosity of the low-order condensate is 1.1 to
In the range of 1.15 or the range of 1.4 to 1.5, the above-mentioned undesirable phenomenon may occur.

The method for obtaining the low-order condensate of the high-melting polyamide having a relative viscosity of 1.1 to 1.5 is not particularly limited, and a batch reaction vessel, a 1- to 3-tank continuous reaction apparatus, The low-order condensate can be produced using a known device such as a tubular continuous reaction device. That is, in the case of producing a low-order condensate of a semi-aromatic polyamide as described above, an aqueous solution of a salt or a monomer having a predetermined composition component composed of a dicarboxylic acid component and a diamine component, which are the polyamide constituent units, is added. Charge into a pressure polymerization kettle, etc., and stir 230-28 under pressure of 21 kg / cm ² G or more while stirring.
It is heated to a temperature of 0 ° C. for a predetermined time. For example, semi-aromatic polyamide 66 / 6T (composition ratio is 66 / by weight)
The low-order condensate of 6T = 50/50) may be produced, for example, under the following polymerization conditions. Adipic acid 10.09 kg, terephthalic acid 10.66 kg, hexamethylenediamine 15.
47 kg and 70.06 g of sodium hypophosphite are added, and 18.11 kg of ion-exchanged water is further added. After sufficiently replacing this mixed liquid with nitrogen, the temperature is raised with stirring,
While releasing the pressure so that the pressure becomes 25 kg / cm ² G,
Heat to 240 ° C. Then, the composition was kept at a polymerization temperature of 240 ° C. and a pressure of 25 kg / cm ² G for 2 hours and then sprayed in the air to give a relative viscosity of 1.20, a melting point of 295 ° C., and [COOH] = 65 × 10 ^{− 5} eq / g,
It is possible to obtain a powdery low-order condensate having [NH ₂ ] = 77 × 10 ⁻⁵ eq / g. In addition, low-order condensates having different relative viscosities can be obtained by the same method only by changing the pressure and temperature conditions. Furthermore, even if the type of raw material monomer or the composition of the charged material is changed, under the same polymerization conditions,
A low-order condensate is obtained.

In the method of the present invention, the above low-order condensate is a twin screw type extruder having an extruder L / D of 33 or more, a screw meshing ratio of 1.4 or more, and a reduced pressure vent port. In accordance with the present invention, preferably, the screw constitution is further constituted by a conveying element, a kneading element and a seal ring element having a draw ratio of 5 to 30%, and melt-polymerized under the operating conditions described later. The relative viscosity of the target product of 2.2 is 2.2.
A high melting point polyamide polymer having an excellent color tone of 3.5 and an excellent mechanical property based on the evaluation method described later is obtained.

By the way, when the low-order condensate is melt-polymerized in the extruder, condensed water is generated, so that the obtained high-melting polyamide resin (hereinafter, simply referred to as "resin") is vigorously foamed. Therefore, it is necessary to quickly remove the generated condensed water to the outside of the extruder system to accelerate the polymerization rate and obtain a resin having a heat history as small as possible. For this reason, the extruder used in the present invention requires a decompression vent port, and further, as will be described later, by adding a seal ring element to the screw configuration, decompression from the decompression vent port is performed. It is desirable to carry out effectively.

In the method of the present invention, as described above, the extruder L / D is 33 or more, preferably 35 to 70.
It is necessary to be. Here, L / D defines the length of the screw, and the diameter of the screw (D)
Is the ratio of the screw length (L) to
This value is effective for comparing the lengths of extruders with different screw diameters. When the L / D is 33 or less, the decompression from the decompression vent is not effectively performed, so that the polymerization rate cannot be increased and only a resin deteriorated by receiving a large heat history can be obtained. Not preferable. In addition, when L / D is in the range of 33 to 35, decompression from the decompression vent port may not be effectively performed, and in the range where L / D exceeds 70, due to the structure of the extruder,
The motor may be overloaded and may not operate, or the core rod of the screw may break.

In order to effectively carry out the depressurization from the above depressurization vent port, it is important that the groove depth of the screw is deep. Therefore, in the method of the present invention,
The screw engagement rate defined below is usually 1.
It should be 4 or more, but 1.4 to 2.4 is more preferable. Here, the meshing ratio is a numerical value representing the groove depth of the screw, and is calculated by the following mathematical formula 1. And, the deeper the groove is, the larger the value of the meshing ratio is.

[0019]

[Equation 1]

If the screw mesh ratio is less than 1.4, the depressurization from the depressurization vent port is not performed effectively as described above, so that the polymerization rate cannot be increased, and therefore, The heat history is large and the resin is deteriorated, which is not preferable. The screw mesh ratio is 2.
If the number exceeds 4, the completely meshing double-thread screw, which is a preferred embodiment of the present invention, will not work as described below.

Further, the screw structure of the extruder in the method of the present invention is preferably a double thread, but is not limited to this. A screw with a meshing ratio of 1.4 or more can only have 1-thread and 2-thread,
A double-threaded screw is more common. Further, in the case of the single-screw screw, the kneading capacity is low although the object to be processed can be conveyed in the extruder. Therefore, for the melt polymerization of the present invention, a single-thread screw structure is possible, but the double-thread screw structure is preferable because there is no advantage of using the single-thread screw structure.

In general, the screw arrangement of an extruder consists of a conveying element (full flight disc) and a kneading element. However, in the polymerization of the resin of the present invention such as a semi-aromatic polyamide, it is necessary to devolatilize condensed water in a specific zone of the extruder, but these screw elements cannot sufficiently devolatilize under reduced pressure. When the degree of pressure reduction is increased in order to perform sufficient vacuum devolatilization, a phenomenon occurs in which the molten resin in the extruder screw is sucked up by the pressure reducing vent port and the pressure reducing line is clogged. Therefore, in the screw configuration of the extruder in the method of the second aspect of the present invention, in addition to the screw element, a seal ring is further added to effectively reduce the pressure from the pressure reducing vent port. Here, the seal ring is an element that functions to block the flow of resin in the extruder, and has a shape as shown in FIG. And the numerical value showing the strength of the effect of blocking the flow of the resin in this extruder is the draw ratio. That is, the aperture ratio is calculated by the following mathematical formula 2. And, the stronger the effect of blocking the flow of resin, the smaller the numerical value of the drawing rate.

[0023]

[Equation 2]

In the method of the second aspect of the present invention, it is necessary that the reduction ratio of the seal ring element is in the range of 5 to 30%. If the draw ratio is less than 5%,
The resin blocking effect is too strong, and the molten resin comes out from the raw material introduction port and the decompression vent port, which is not preferable. Further, if the draw ratio is larger than 30%, the resin blocking effect is too weak, and when attempting to reduce the pressure from the decompression vent port, air cannot be decompressed by sucking air from the raw material introduction port, or the extruder has a plurality of decompression vents. In the case of having a port, there is a problem that the molten resin is sucked up to the decompression vent port where the degree of decompression is strongest and the molten resin comes out from the decompression vent port, which is not preferable.

As described above, in the method of the present invention, the apparatus for producing the high melting point polyamide has a specific L /
D, having a screw structure and a screw engagement ratio, preferably further having a specific screw configuration, and having a specific condition such as having a pressure reducing vent port 2
A twin-screw extruder, that is, a twin-screw extruder, specifically, a twin-screw extruder such as a co-rotating / meshing type, a different-direction rotating / meshing type, which has the specific conditions described above. It can be preferably mentioned.

When using other types of extruders, for example,
In a twin-screw extruder with a three-thread screw and a shallow groove structure (meshing ratio is less than 1.4), the amount of polymerization is small and the residence time of the resin in the extruder is long, so Only the deteriorated resin can be obtained due to the heat history at. Further, as described above, the condensed water cannot be sufficiently removed from the depressurization vent port, so that the resin does not foam to form a strand. In the extruder with L / D = 33 or less, even if the extruder has a double-thread screw and a deep groove structure, the same result as in the case of the triple-thread screw and the shallow groove structure is brought about. Further, in the single-screw type extruder, the condensed water generated during the polymerization cannot be removed from the inside of the extruder system, and the polymerization does not proceed.
Therefore, in the method of the present invention, it is not preferable in any case to use an extruder other than the twin-screw type extruder having the above specific conditions.

Next, the operating conditions of the extruder in the method of the present invention will be described. The melt polymerization temperature is 10 to 40 ° C. higher than the melting point of the resin, and particularly 10 to 3 higher than the melting point of the resin.
It is preferable that the temperature is 0 ° C. higher. If the melt polymerization temperature is lower than the melting point of the resin + 10 ° C., the melt viscosity of the resin becomes too high in the extruder, and a portion having a temperature lower than the melting point of the resin occurs, and the resin solidifies during the production. , There is a possibility of causing ejection failure. Further, when the melt polymerization temperature is higher than the melting point of the resin + 30 ° C, the resin tends to be thermally decomposed and deteriorated to cause coloring and deterioration of mechanical properties, and particularly the melting point of the resin + 40 ° C.
If it is higher, the tendency becomes remarkable, which is not preferable. In particular, when using a low-order condensate having a high melting point due to, for example, a high content of nylon 6T, the upper limit temperature should be 340 ° C. or lower in order to prevent thermal decomposition or thermal deterioration of the obtained polyamide polymer. Is preferred.

The melt polymerization temperature is controlled, for example, by using a cylinder of the extruder as a block system,
An electric heater is wound around the cylinder to control heating for each block of the cylinder, or a jacket structure is used in which the cylinder can be trimmed in blocks, and each block of the cylinder can be steamed as desired. A known method such as flowing a heating medium such as or a cooling medium such as cooling water into the jacket portion may be performed.

The residence time of the resin in the extruder is 60 to 3
It is preferably 00 seconds, particularly 60 to 200 seconds. When the residence time is less than 60 seconds, the degree of polymerization of the low-order condensate in the extruder becomes insufficient, and the desired resin having good mechanical properties cannot be obtained, and the residence time is 30
If the time is longer than 0 seconds, the heat history at a high temperature becomes too long and the resin deteriorates, which is not preferable in any case. If the residence time is in the range of 200 to 300 seconds, the resin may be deteriorated due to heat history at high temperature. Therefore, in the method of the present invention, the supply amount of the low-order condensate to the extruder, the screw diameter (D) of the extruder, L /
D, the number of rotations of the screw, etc. are appropriately selected, and the residence time of the resin in the extruder is controlled within the above range.

Further, in the method of the present invention, as described above, it is important to effectively reduce the pressure from the pressure reducing vent port, and it is preferable that the degree of pressure reduction at the vent port is 700 Torr or less, and 500 Torr. The following is more preferable. Decompression degree at the vent is 700 Tor
If it is less than r, the decompression from the decompression vent cannot be performed effectively, so the polymerization rate in the extruder cannot be increased, and only deteriorated resin can be obtained, or sufficient condensation water can be removed. It is not preferable because the resin does not foam to form strands. Further, in order to reliably prevent the occurrence of these unfavorable phenomena, the degree of pressure reduction at the pressure reducing vent port is in the above more preferable range, that is,
It should be below 500 Torr. Such decompression can be achieved, for example, by connecting the decompression vent port to a known vacuum device such as a Nash pump.

By the way, the relative viscosity of the resin obtained by the production method of the present invention is 2.2 to 3.5 as described above.
However, this can be controlled by the degree of pressure reduction at the vent port and the processing flow rate of the extruder. Here, it should be noted that the processing flow rate is related to the retention time, and the reduction of the processing flow rate lengthens the retention time. When the residence time becomes long, the heat history becomes large and the resin deteriorates, as described above. Therefore, it is better to increase the processing flow rate as much as possible, but by using an extruder with the above-mentioned specific conditions suitable for the method of the present invention, the highest processing flow rate can be obtained.
This enables stable melt polymerization.

The resin obtained by the production method of the present invention is, as described above, a high melting point polyamide polymer which has not been subjected to heat deterioration, that is, has not been colored due to heat deterioration. In the present invention, the degree of deterioration of the resin is evaluated by the degree of coloring, but the evaluation method is not limited to this. Examples of the method for evaluating the degree of coloring of the resin in the present invention include the following three types of methods. In the first method, the obtained resin is, for example, a semi-aromatic polyamide 66 / 6T (the composition ratio is 66 / by weight).
This is an evaluation method when 6T = 50/50). That is, in this case, 1 g / dl of the resin not deteriorated
When the transmitted light intensity at a thickness of 1 cm of a solution dissolved in formic acid at a concentration of is measured, there is aromatic absorption in the wavelength range of 250 nm to 310 nm, but in the region of 320 nm or more,
By nature, there is no absorption of aromatic and amide bonds. But,
When the resin undergoes thermal history and deteriorates
Absorption due to a deteriorated product also appears in the wavelength region of 50 nm, and the mechanical properties of the resin start to deteriorate. When the transmittance of light having a wavelength of 330 nm and having a thickness of 1 cm of the solution is less than 80%, the tensile elongation and impact strength of the resin are particularly lowered. Therefore, the resin obtained by the method of the present invention is required to have a transmittance of 80% or more for light having a wavelength of 330 nm and having a thickness of 1 cm of a solution dissolved in formic acid at a concentration of 1 g / dl.

The second method is an evaluation method performed when the obtained resin is a semi-aromatic polyamide and the evaluation cannot be performed by the first method. That is, in the case of a semi-aromatic polyamide, when the aromatic component increases, the solubility in formic acid deteriorates, and the evaluation may not be possible with the first evaluation method. In that case, the polymer was added at a concentration of 1 g / dl to 9
The transmitted light intensity at a thickness of 1 cm of the solution obtained by dissolving in 8% sulfuric acid is measured. When the solvent is changed, the absorption wavelength range of the aromatic is changed, and in the resin which is not deteriorated, the absorption of the aromatic is observed in the wavelength range of 250 nm to 330 nm. There is no binding uptake. However, when the resin undergoes a thermal history and deteriorates, absorption due to the deteriorated product also appears in the wavelength region of 340 to 350 nm, and the mechanical properties of the resin start to deteriorate. When the transmittance of light having a wavelength of 350 nm and having a thickness of 1 cm of the solution is less than 80%, the tensile elongation and impact strength of the resin are particularly lowered. Therefore, the resin obtained by the method of the present invention also has a transmittance of light having a wavelength of 350 nm of 1 cm in a solution prepared by dissolving 98% sulfuric acid at a concentration of 1 g / dl.
% Or more is required.

The third method is a method of evaluating the YI (Yellowness Index) value of the obtained resin pellets. That is, when the resin undergoes heat history and deteriorates, the originally colorless and transparent resin starts to be colored yellow. The YI is used to measure the degree of this yellow color. The definition of this numerical value is JI
SK7105, section 6.3, ASTM D1925-7
0 and ISO / DIS 3558. In the resin pellet obtained by the production method of the present invention, when the YI value is larger than 20, the mechanical properties of the resin start to deteriorate. Therefore, in the present invention, it is necessary that the YI value of the obtained resin pellet is 20 or less.

In the method of the present invention, the high melting point polyamide resin may be added to the high melting point polyamide resin, if necessary, as an inorganic or organic phosphoric acid compound acting as a catalyst during melt polymerization in an extruder, a heat stabilizer, and a weather resistance. It is also possible to add stabilizers, plasticizers, lubricants, crystal nucleating agents, pigments, dyes, other polymers and the like. Further, the high melting point polyamide resin produced by the method of the present invention can also be molded by ordinary melt molding, injection molding, extrusion molding, compression molding or the like.

[0036]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples below, but these do not limit the present invention in any way. For example, in the present invention, the low-order condensate (A) used in the following Examples and Comparative Examples,
The composition is not limited to (B) and (C),
Even with other compositions, a high melting point polyamide resin can be obtained by the same melt polymerization as in the following Examples and Comparative Examples by setting the temperature of the extruder to be about 20 ° C. higher than the melting point of the resin. .

In the following examples and comparative examples, parts represent parts by weight. Moreover, each physical property shown in the following Examples and Comparative Examples was measured by the following test methods. (1) Tensile Strength, Elongation: ASTM D-638 (2) Bending Strength, Bending Elastic Modulus: ASTM D-790 (3) Izod Impact Strength: ASTM D-256 (4) Viscosity: Low Condensate or Polymerized to 98% sulfuric acid,
Dissolve at a concentration of 1 g / dl and measure relative viscosity at 25 ° C according to JIS
It was measured by K6810. (5) Melting point: Measured with a DSC-210 manufactured by Seiko Denshi KK under a nitrogen atmosphere at a temperature rising rate of 20 ° C./min. (6) Unterminated group concentration ([COOH]) of the low-order condensate: 0.5 g of the low-order condensate was dissolved in 50 ml of hot benzyl alcohol and measured with a 1/50 N-KOH methanol solution. (7) Unterminated group concentration of low-order condensate ([NH ₂ ]): 1 g of low-order condensate was dissolved in 100 ml of a phenol / ethanol (weight ratio: 50/50) mixed solution, and a 1 / 50N hydrochloric acid aqueous solution was used. Measured and determined. (8) Transmittance of light in formic acid solution at wavelength of 330 nm: A solution prepared by dissolving a polymer in formic acid at a concentration of 1 g / dl was put into a prismatic quartz cell having a thickness of 1 cm on the inner surface, and the sample solution had a thickness of 1
The transmitted light intensity at a wavelength of 330 nm, which passes through cm, was measured and determined by the following mathematical formula 3.

[0038]

(Equation 3)

(9) Light transmittance in sulfuric acid solution at a wavelength of 350 nm: A solution prepared by dissolving a polymer in 98% sulfuric acid at a concentration of 1 g / dl was placed in a prismatic quartz cell having an inner surface thickness of 1 cm.
The transmitted light intensity at a wavelength of 350 nm, which passes through the sample solution having a thickness of 1 cm, was measured and determined by the following mathematical formula 4.

[0040]

[Equation 4]

(10) YI value: ASTM D1925-
70 of the color meter manufactured by Nippon Denshoku Industries Co., Ltd.
The YI value of the resin pellet was measured using DJ-300A.

Reference Example 1 [Production of Lower Condensate (A)] Adipic acid 1 was placed in an autoclave having a volume of 70 liters.
0.09 kg, 10.66 kg of terephthalic acid, 15.47 kg of hexamethylenediamine and 70.6 g of sodium hypophosphite are added, and ion-exchanged water 18.11 is added.
kg was added. After thoroughly replacing this mixed liquid with nitrogen,
The temperature was raised with stirring, and the temperature was raised to 240 ° C. while releasing the pressure so that the pressure became 25 kg / cm ² G. After that, under the conditions of a polymerization temperature of 240 ° C. and a pressure of 25 kg / cm ² G, 2
After holding for a period of time, it was sprayed in the air to obtain a powdery low-order condensate (A). The obtained low-order condensate (A) has a relative viscosity of 1.20, a melting point of 295 ° C., and [COOH] = 65 × 10.
^-5 eq / g, and [NH ₂ ] = 77 × 10 ^-5 eq / g
Met.

Reference Example 2 [Production of low-order condensate (B)] The polymerization conditions were as follows: polymerization temperature of 240 ° C. and pressure of 2
Change to 5 kg / cm ² G, polymerization temperature 270 ° C., pressure 3
A powdery low-order condensate (B) was obtained in the same manner as in Reference Example 1 except that the amount was 0 kg / cm ² G. The obtained low-order condensate (B) has a relative viscosity of 1.39, a melting point of 297 ° C., and a [C
OOH] = 33 × 10 ⁻⁵ eq / g and [NH ₂ ] = 4
It was 3 × 10 ⁻⁵ eq / g.

Reference Example 3 [Production of low-order condensate (C)] The polymerization conditions were as follows.
Polymerization temperature 220 ° C, pressure 2 instead of 5 kg / cm ² G
A powdery low-order condensate (C) was obtained in the same manner as in Reference Example 1 except that 0 kg / cm ² G was used. The obtained low-order condensate (C) has a relative viscosity of 1.05, a melting point of 235 ° C., and a [C
OOH] = 365 × 10 ⁻⁵ eq / g, [NH ₂ ] = 37
It was 7 × 10 ⁻⁵ eq / g. Therefore, the three types of low-order condensates (A), (B) and (C) having different relative viscosities obtained as described above were used as the feedstock in the following Examples and Comparative Examples.

Examples 1 to 3 In Examples 1 to 3, the low-order condensate (A) obtained in Reference Example 1 was used as UME-55 (Ube Industries, Ltd.).
Twin screw type extruder (double thread, deep groove, screw diameter 55 mm, L / D = 60, engagement ratio 1.49,
Supplied into the extruder through a raw material inlet (with a vacuum vent),
In the first embodiment, the processing flow rate is 40 kg / hr, the pressure reduction degree is 500 Torr, and in the second embodiment, the processing flow rate is 60 k.
g / hr, decompression degree 300 Torr, in Example 3, treatment flow rate 80 kg / hr, decompression degree 100 Torr,
The polymerization temperature was 320 ° C. in each of Examples 1, 2 and 3 for the melt polymerization. In each of Examples 1 to 3, the polyamide resin was successfully polymerized, and a pale yellow strand was obtained in Example 1, and a white bubble-free strand was obtained in Examples 2 and 3. Table 1 shows the main polymerization conditions in Examples 1 to 3 and the properties and physical properties of the obtained polymers.

Example 4 The same extruder as in Example 3 was used, but the low-order condensate (A) obtained in Reference Example 1 was put in the middle of the cylinder instead of being put in from the usual raw material introduction port. Example 3
L / D = 34 instead of L / D = 60 for the extruder in
Melt polymerization was carried out under the same extruder conditions as in Example 3 except that the operation was carried out in the above state. Polymerization of the polyamide resin was possible, but bubbles were formed in the strand. Table 1 shows the main polymerization conditions and the properties and physical properties of the obtained polymer. Decompression degree and processing flow rate are 200 Tor, respectively
r and 34 kg / hr, which was not as high as in Example 3.

Example 5 Using the same extruder as in Example 3, the low-order condensate (B) obtained in Reference Example 2 was used as the feed material instead of the low-order condensate (A) in Example 3. Melt polymerization was carried out in the same manner as in Example 3 except that the treatment flow rate was changed to 80 kg / hr and 100 kg / hr. The polyamide resin could be polymerized well and a white bubble-free strand was obtained. Table 1 shows the main polymerization conditions and the properties and physical properties of the obtained polymer.

Comparative Example 1 The same extruder as in Example 1 was used, and the degree of vacuum was 500 Torr.
Was changed to 760 Torr, that is, decompression was not performed, and the treatment flow rate was 40 kg / hr.
Melt polymerization was performed in the same manner as in Example 1 except that the content was changed to 30 kg / hr. The polyamide resin could be polymerized well, but a yellow bubbled strand was obtained. Table 1 shows the main polymerization conditions and the properties and physical properties of the obtained polymer.

[0049]

[Table 1]

Comparative Example 2 Instead of the extruder in Example 1, a PCM-45 (manufactured by Ikegai Seisakusho Co., Ltd.) twin screw type extruder (three-thread screw,
Shallow groove, screw diameter 45 mm, L / D = 30, meshing ratio 1.26, with vacuum vent), and polymerization conditions such as processing flow rate and vacuum degree were as shown in Table 2. In the same manner as in Example 1, the low-order condensate (A) obtained in Reference Example 1 was supplied to the extruder to carry out melt polymerization. The properties and physical properties of the obtained polymer were as shown in Table 2. The processing flow rate was as low as 8 kg / hr. Further, since the pressure could not be reduced, the resin foamed and could not be obtained as a strand. The resin was colored light yellow.

Comparative Example 3 Instead of the extruder in Example 1, a UME-50 (manufactured by Ube Industries, Ltd.) twin screw type extruder (two-thread screw, shallow groove, screw diameter 50 mm, L / D = 34) , Mesh ratio 1.27, with a vacuum vent), and the same procedure as in Example 1 except that the polymerization conditions such as processing flow rate and degree of vacuum were as shown in Table 2. To
The low-order condensate (A) obtained in Reference Example 1 was supplied and melt-polymerized. The properties and physical properties of the obtained polymer were as shown in Table 2. The processing flow rate was as low as 14 kg / hr. Further, the situation was better than in the case of Comparative Example 2, and although the pressure could be reduced a little, foaming of the resin could not be removed and no strand was formed. The resin was colored light yellow.

Comparative Example 4 Instead of the extruder in Example 1, a UME-55 (manufactured by Ube Industries, Ltd.) twin screw type extruder (two-thread screw, deep groove, screw diameter 55 mm, L / D = 44, (Meshing ratio 1.49, with vacuum vent)
It was changed to 0 Torr to 760 Torr, that is, decompression was not performed, and the processing flow rate was 40
Other than changing to 42 kg / hr instead of kg / hr,
Melt polymerization was carried out in the same manner as in Example 1. Table 2 shows the main polymerization conditions and the properties and physical properties of the obtained polymer. Since the pressure was not reduced, the resin foamed and did not form a strand. Since the residence time of the resin in the extruder was the same as that in Example 1, the resin was not colored.

Comparative Example 5 The same extruder as in Comparative Example 4 was used in place of the extruder in Example 1, and the pressure reduction degree was changed to 500 Torr to 760.
Torr, that is, no pressure reduction was performed, and the treatment flow rate was reduced so that the relative viscosity of the obtained resin was the same as that in Example 1, and the same procedure as in Example 1 was performed. Then, melt polymerization was performed. Table 2 shows the main polymerization conditions and the properties and physical properties of the obtained polymer. Since the pressure was not reduced, the resin foam could not be completely removed,
It became a strand containing bubbles. Processing flow rate is 25kg
/ Hr and the strand was colored light brown.

[0054]

[Table 2]

Comparative Example 6 The same extruder as in Comparative Example 4 was used in place of the extruder in Example 1, and the reference example was used instead of the low-order condensate (A) in Example 1 as a feed material. Melt polymerization was performed in the same manner as in Example 1 except that the low-order condensate (C) obtained in 3 was used. Since the relative viscosity of the low-order condensate (C) was too low, the low-order condensate (C) was fixed at the raw material introduction port of the extruder and could not be introduced into the extruder.

Example 6 Two pressure reducing vent ports were provided, and the screw elements on the upstream side of these pressure reducing vent ports were respectively
Seal ring elements S1 and S2 (drawing ratio is S
UME-55 (manufactured by Ube Industries, Ltd.) twin-screw type extruder (two-thread screw) having a screw configuration consisting of a conveying element, a kneading element and a seal ring element with 1 = 12% and S2 = 20%). ,
Deep groove, screw diameter 55 mm, L / D = 44, mesh ratio 1.49, with vacuum vent), and the low-order condensate obtained in Reference Example 1 from the raw material inlet of the extruder into the extruder ( A) is supplied, the processing flow rate is 45 kg / hr, and the polymerization temperature is 3
Melt polymerization was performed at 20 ° C. and a reduced pressure of 100 Torr. The polyamide resin could be polymerized well and a white bubble-free strand was obtained. Table 3 shows the main polymerization conditions and the properties and physical properties of the obtained polymer.

Example 7 The sealing element of the extruder had a drawing ratio of S1 = 12.
% And S2 = 20%, the draw ratio is S
Melt polymerization of the low-order condensate (A) obtained in Reference Example 1 was carried out under the same extruder conditions as in Example 6 except that 1 = 20% and S2 = 30% were used. Polymerization of the polyamide resin was possible, but bubbles were formed in the strand. Table 3 shows the main polymerization conditions and the properties and physical properties of the obtained polymer. Decompression degree and processing flow rate are 3
50 Torr and 38 kg / hr, which was not as high as that of Example 6.

Example 8 The same extruder as in Example 7 was used, and the feedstock was
Instead of the low-order condensate (A) in Example 7, Reference Example 2
Using the low-order condensate (B) obtained by the above, changing the degree of vacuum to 200 Torr by changing the degree of vacuum to 350 Torr, and changing the treatment flow rate to 38 kg / hr and 60 k.
Melt polymerization was carried out in the same manner as in Example 7 except that g / hr was used. The polyamide resin could be polymerized well and a white bubble-free strand was obtained.
Table 3 shows the main polymerization conditions and the properties and physical properties of the obtained polymer.

Example 9 The same extruder as in Example 6 was used, and the feedstock was
Instead of the low-order condensate (A) in Example 6, Reference Example 2
Using the low-order condensate (B) obtained by, and changing the treatment flow rate to 45 kg / hr, 70 kg / hr
Melt polymerization was carried out in the same manner as in Example 6 except that Can polymerize polyamide resin well,
A white, bubble-free strand was obtained. Table 3 shows the main polymerization conditions and the properties and physical properties of the obtained polymer.

Comparative Example 7 Instead of the extruder in Example 6, a UME-50 (manufactured by Ube Industries, Ltd.) twin screw type extruder (two-thread screw, shallow groove, screw diameter 50 mm, L / D = 34) , Mesh ratio 1.27, with a vacuum vent), and the seal ring elements of the extruder were drawn from S1 = 12% and S2 = 20%, respectively.
% And S2 = 35%, and except that the polymerization conditions such as the treatment flow rate and the degree of reduced pressure were as shown in Table 3, the same procedure as in Example 6 was repeated except that the extruder was used as a reference example. The low-order condensate (A) obtained in 1 was supplied and melt-polymerized. The main polymerization conditions and the properties and physical properties of the obtained polymer were as shown in Table 3. Processing flow rate is 1
It was as low as 4 kg / hr, and could be operated only under almost the same operating conditions as when using an extruder having no seal ring element in the screw configuration. Then, the resin foamed and did not become a strand. Also, the resin is
It was colored pale yellow.

[0061]

[Table 3]

[0062]

According to the production method of the present invention, the twin-screw type extruder has an L / D of 33 or more, a screw meshing ratio of 1.4 or more, and a pressure reducing vent, and preferably the screw constitution. Is a combination of a transport element, a kneading element, and a seal ring element with a draw ratio of 5 to 30%.
By operating under a reduced pressure condition of not more than r, stable extruder polymerization can be carried out, and therefore, a high melting point polyamide having a melting point close to the thermal decomposition temperature can be stably and efficiently produced. Further, the obtained polyamide resin has a small heat history, so that it is not thermally deteriorated, has a good color tone, and has excellent mechanical properties.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a relationship between a screw peak diameter and a screw root diameter in the case of a twin-screw extruder having a double-thread screw structure.

FIG. 2 is a diagram illustrating a relationship between a screw crest diameter and a screw trough diameter in the case of a twin-screw extruder having a three-thread screw structure.

FIG. 3 is a diagram showing a cross-sectional area of resin passing through a conveying element portion of an extruder.

FIG. 4 is a view showing a cross-sectional area of resin passing through a seal ring element portion of an extruder.

Claims (5)

[Claims] 1. When the low-condensation product of a high melting point polyamide having a relative viscosity of 1.1 to 1.5 is polymerized by an extruder to produce the high melting point polyamide, L / D is 33 or more,
Using a twin-screw extruder with a screw mesh ratio of 1.4 or more and a reduced pressure vent port, the relative viscosity is 2.2 to 3.5 under a reduced pressure condition of 700 Torr or less, and coloring is caused by heat deterioration. A method for producing a high melting point polyamide, which comprises producing a polymer having no melting point. 2. When a low-condensation product of a high-melting polyamide having a relative viscosity of 1.1 to 1.5 is polymerized by an extruder to produce the high-melting polyamide, L / D is 33 or more,
Using a twin screw extruder having a screw engagement ratio of 1.4 or more and a decompression vent port, and the screw configuration is a conveying element, a kneading element, and a seal ring element with a draw ratio of 5 to 30%, 700 To
Under a reduced pressure condition of rr or less, the relative viscosity is 2.2 to 3.5.
2. A method for producing a high melting point polyamide, which comprises producing a polymer which is not colored due to heat deterioration. 3. The polymer obtained by the method according to claim 1 or 2, which is dissolved in formic acid at a concentration of 1 g / dl and has a transmittance of 80 cm at a wavelength of 330 nm and a thickness of 1 cm. % High-melting polyamide. 4. The polymer obtained by the method according to claim 1 or 2, which is dissolved in 98% sulfuric acid at a concentration of 1 g / dl and has a transmittance of light having a thickness of 1 cm and a wavelength of 350 nm. Is 80% or more, a high melting point polyamide. 5. A high-melting polyamide, which is a polymer obtained by the method according to claim 1 or 2, wherein the pellet has a YI value of 20 or less.