JPH0438766B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a two-stage polymerization method for 12-aminododecanoic acid, and more specifically, 12-aminododecanoic acid is polymerized in two stages, prepolymerization and postpolymerization, and This invention relates to a two-stage polymerization method of 12-aminododecanoic acid, in which nylon-12 of extremely high molecular weight is obtained by adding a viscosity stabilizer to the polymerization product and post-polymerizing it. (Prior Art) A method for producing nylon-12 by polymerizing 1,2-aminododecanoic acid in a molten state is known. When this method is carried out continuously, powdered 12-
A method is used in which aminododecanoic acid is continuously supplied from the top of the polymerization tank, the polymerization reaction proceeds in a molten state by heating it in the polymerization tank, and the produced polymer is continuously taken out from the bottom of the polymerization tank. It is being said.
In such a polymerization method, water is produced as a by-product as a result of the condensation reaction between amino groups and carboxyl groups.
The amount of this water is larger in the upper part of the melt in the polymerization tank.
It decreases toward the bottom of the melt, but in any case, it is inevitable that water will be produced as a by-product during the polymerization of nylon-12. In addition, in the conventional polymerization method described above, the lower part of the melt is under pressure due to its own weight, and furthermore, the concentration of free amino groups and free carboxyl groups is diluted, so amino groups The dehydration condensation reaction between nylon and carboxyl groups becomes difficult to proceed, making it impossible to obtain nylon-12 with a sufficiently high molecular weight. Therefore, when trying to obtain nylon-12 with a higher molecular weight, nylon-12 with a not sufficiently high molecular weight obtained by the above polymerization method must be used.
A discontinuous two-stage polymerization method must be adopted in which the polymerization of 12 is carried out in the same polymerization tank or in a separate polymerization tank under normal pressure or reduced pressure and at a higher polymerization temperature. In this discontinuous two-stage polymerization method, the molecular weight of the final product, high molecular weight nylon-12, is adjusted by
This is done by adjusting the temperature of the polymer, residence time, amount of water produced as a by-product, etc. in the latter stage of polymerization, but it is extremely difficult to finely adjust these conditions, and this results in The molecular weight of the product nylon-12 varies widely, and such a method for producing nylon-12 cannot be said to be a preferable method. Furthermore, in this discontinuous two-stage polymerization method, after the polymerization reaction is completed, the nylon is removed from the polymerization tank.
When taking out nylon-12, a considerable amount of nylon-12 remains in the polymerization tank, adhering to the vessel walls. This is an unavoidable problem because the polymerization is carried out in a molten state, but as the polymerization reaction is repeated discontinuously, this residue undergoes a long thermal history, so it gradually deteriorates. This degraded nylon-12 is mixed into the nylon-12 product, resulting in a decrease in the quality of the nylon-12 product. Therefore, in order to prevent such inconveniences, the interior of the polymerization tank is frequently cleaned, but in this case, productivity is reduced due to wasted cleaning time, and economical costs are lost due to wasted cleaning materials. The problem arises that significant losses are unavoidable. (Means for Solving the Problems) According to the present invention, 12-aminododecanoic acid is prepolymerized in a first polymerization tank, and 1 g/100 ml of 12-aminododecanoic acid is prepared in 98% sulfuric acid.
Relative viscosity measured at 25°C at a concentration of 1.35 to 2.20
A first step of producing a pre-polymerized product of A second step of polymerizing 12-aminododecanoic acid is provided. In this specification, relative viscosity (ηr) is defined by the following formula: ηr=η/ηo, where η is the viscosity of the sample measured at 25±0.05°C at a concentration of 1 g/100 ml in 98% _{H2SO4 .} Yes, ηo
is defined as the viscosity of 98% H ₂ SO ₄ measured under the above conditions. (Measurement method JIS K 6810) (Function) The present invention performs polymerization of 12-aminododecanoic acid in two stages: a prepolymerization step and a postpolymerization step,
The relative viscosity obtained in the prepolymerization step is 1.35 to 2.20.
By adding a viscosity stabilizer to the pre-polymerization product and performing post-polymerization, nylon-12 with a high molecular weight with a relative viscosity of 1.9 to 3.5 is produced. It has the characteristic that a homogeneous high molecular weight nylon-12 can be easily obtained in a short time. Generally, it is well known that a viscosity stabilizer is added to the polymerization of polyamide in order to suppress the increase in viscosity accompanying the polymerization of polyamide. However, in the present invention, during the polycondensation of 12-aminododecanoic acid, prepolymerization is performed without adding a viscosity stabilizer in the prepolymerization step in which the viscosity of the polymerization product is relatively low, and the resulting prepolymerization product has a viscosity of Post-polymerization is carried out by adding a stabilizer. That is, by adding a viscosity stabilizer to the prepolymerization product, the increase in viscosity in the postpolymerization step is suppressed, thereby promoting the dehydration condensation between amino groups and carboxyl groups, and also the removal of by-product water. It becomes easier,
It becomes possible to produce homogeneous and high molecular weight nylon-12 in a short polymerization time. Moreover, by suppressing the increase in viscosity, the post-polymerization product can be easily extracted, and the problem of quality deterioration due to the contamination of degraded nylon-12 can be solved. The relationship between the amount of the viscosity reducing agent added and the viscosity reduction is shown in FIG. 5 using stearic acid as an example. (Description of preferred embodiments) An example of the polymerization method of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of a polymerization apparatus used to carry out an example of the two-stage polymerization method of the present invention.
Figure 2 is a sectional view taken along line A-A in Figure 1, Figures 3 and 4.
The figure is a sectional view taken along the line BB in FIG. 1. A monomer supply port 2 and an exhaust port 3 are provided at the top of the vertical first polymerization tank (pre-polymerization tank), a pre-polymerization product discharge port 4 is provided at the bottom, and a heating port is provided on the outer peripheral side wall. A jacket 5 for use is provided. 1st
A heater 6 is provided slightly above the center of the inside of the polymerization tank 1. A cylindrical heating plate 8 having a heat medium flow passage 7 at
, three heat medium supply pipes 9 for supplying the heat medium to the heat medium flow passages 7 connected to the lower part of each heating plate, and further connected to the lower part of each heating plate 8 for discharging the heat medium. It is composed of three heat medium discharge pipes 10. A rotary stirrer 12 is provided above the heater 6 and has rotating stirring blades 11 located between each heating plate 8 and between the heater 6 and the inner wall of the polymerization tank 1. It is designed to be twisted and rotated. A monomer measuring feeder 14, an inert gas supply pipe 15, and an inert gas measuring feeder 16 connected thereto are provided above the monomer supply port 2, and the monomer and inert gas are The monomers are supplied from the respective supply ports, mixed in the monomer supply pipe 17, and then supplied to the polymerization tank 1. The second polymerization tank (post-polymerization tank) 30 is arranged horizontally, and has a cylindrical cross section (Fig. 3) or an inverted semicylindrical shape (Fig. 4), and its central axis is approximately horizontal. A pre-polymerization product supply port 31 is provided at the bottom of one horizontal end, and a polymer discharge port 32 is provided at the bottom of the other end, and a discharge pipe is connected to the discharge port. 33, and a screw extractor 34 driven by a motor _M3 is provided in this discharge pipe. An inert gas supply port 35 is provided at the top of one lateral end of the second polymerization tank 30, and an exhaust port 36 is provided at the top of the other lateral end. In addition, the second polymerization tank 3
A heating jacket 37 is provided on the outer peripheral wall of the second polymerization tank 30.
The stirring shaft 38 is located slightly below the horizontal central axis of the stirring shaft 38, and stirring blades 39 are attached to the stirring shaft 38, and a stirrer rotated by a motor _M2 is provided. Although the second polymerization tank 30 has a horizontal arrangement as described above, having the head space 48 above the melt filling section 47 is extremely effective in forcibly removing water that is produced as a by-product in the post-polymerization process. is important. That is,
By providing a head space in the horizontal and longitudinal direction so as to be in contact with the surface of the melt, and by providing a stirring mechanism 39 that stirs the melt in a direction perpendicular to this head space, moisture etc. in the melt 47 can be absorbed into the head space 48. It will be easily volatilized. The pre-polymerization product outlet 4 of the first polymerization tank 1 and the second
The prepolymerization product supply port 31 of the polymerization tank 30 is connected to the polymer transfer pipe 40 and a gear pump 41. A heating jacket 42 is provided around the polymer transfer pipe 40 and gear pump 41. The lower part of the viscosity stabilizer tank 43 and the polymer transfer pipe 40 are connected to the viscosity stabilizer supply pipe 44 and the gear pump 4.
5, so that the viscosity stabilizer can be added and mixed into the prepolymer. Viscosity stabilizer tank 4
3. Viscosity stabilizer supply pipe 44 and gear pump 4
A heating jacket 46 is provided on the outer periphery of each of the heating jackets 5, respectively. The first polymerization tank 1 may be of any type known per se, and is a cylindrical container whose lower part is shaped like an inverted cone. The lower part of the first polymerization tank 1 may be dish-shaped or dome-shaped. The ratio H ₁ /D ₁ between the depth (H ₁ ) and the inner diameter (D ₁ ) of the first polymerization tank 1 is generally 2.0 to 8.0. Powdered 12-aminododecanoic acid, which is a monomer, is supplied to the monomer metering feeder 14 from a monomer tank (not shown) through a pipe 18, and the monomer metering feeder adjusts the feed rate at a desired rate. The monomer weighed in is supplied to the first polymerization tank 1 from the monomer supply port 2. 12-aminododecanoic acid has a particle size of 120
It is preferable that it passes through a Tyler standard mesh sieve, and it is further preferable that the water content is simply removed to a moisture content of 0.1% by weight or less. The inert gas from the pipe 19 is metered to the desired feed rate in the inert gas metering feeder 16 and passes through the inert gas supply tube 15 to the monomer at the monomer outlet of the monomer metering feeder 14. They are mixed and supplied to the first polymerization tank 1 from the monomer supply port 2 through the monomer supply pipe 17. The supply ratio of 12-aminododecanoic acid and inert gas is preferably such that the amount of inert gas is 0.003 to 0.02 m ³ in terms of standard conditions per 1 kg of 12-aminododecanoic acid. If the amount of inert gas supplied is less than the above range, the monomer supply port 2 is likely to be clogged with monomer, and if the amount of inert gas supplied is more than the above range, the exhaust port 3 is likely to be clogged. 12−, which escapes along with the water vapor produced as a by-product during the polymerization reaction.
The amount of aminododecanoic acid increases and the consumption rate worsens. Note that the inert gas supply pipe 15 is replaced by the monomer supply pipe 1.
7 and open inside the monomer supply pipe 17. From the exhaust port 3, water vapor produced as a by-product during the polymerization reaction of 12-aminododecanoic acid is discharged to the outside of the first polymerization tank together with an inert gas. The heating jacket 5 may be made into one piece as shown in FIG. 1, or may be divided into two or more pieces. When the heating jacket 5 is divided into two or more pieces, there is an advantage that the longitudinal temperature distribution of the polymerization reaction product can be adjusted as desired. As the heat medium passed through the heating jacket 5, either a liquid heat medium or a gas heat medium can be used depending on the operating temperature. As the heat medium, for example, water, aromatic compounds, etc. can be used. The heat medium supply pipe 9 has one end connected to the heating jacket 5 and the other end connected to the lower part of each heating plate 8 to supply the heat medium in the heating jacket to the heat medium flow passage 7 of each heating plate 8. Although it is set up to supply
The heat medium supply pipe 9 may not be connected to the heating jacket 5, so that a heat medium other than the heat medium in the heating jacket can be supplied. This makes it possible to adjust the temperature independently of the temperature of the heating medium in the heating jacket. The number of heat medium supply pipes 9 and heat medium discharge pipes 10 may be one or an appropriate number of two or more. In this specification, the polymerization in the first polymerization tank 1 is referred to as "pre-polymerization", and the polymerization in the second polymerization tank 30 is referred to as "post-polymerization". In the first polymerization tank 1, 12-aminododecanoic acid and its prepolymer are present in a molten liquid phase.
The amount of 12-aminododecanoic acid supplied is adjusted to such an amount that the residence time of the reactants in the polymerization tank is about 4 to 9 hours. The liquid level of the contents in the polymerization tank is kept constant so that it completely covers the heating plate 8 and is located slightly below the stirring arm 13 to which the stirring blade 11 is attached. The temperature of the liquid phase of the contents in the first polymerization tank can generally be maintained within the range of 180 to 340°C to carry out the polymerization reaction. to 180 to 260℃, especially 200 to 220℃,
The temperature in the center should be 200 to 260℃, especially 220 to 240℃.
℃, lower temperature 220~280℃, especially 230~250℃
It is preferable to maintain the temperature at °C, and it is important to maintain the temperature of the upper part of the liquid phase, especially the part near the liquid surface, within the above range. If the temperature at the upper part of the liquid phase is lower than the above range, the melting of 12-aminododecanoic acid will be slow near the liquid surface, the solid content will increase near the liquid surface, and smooth stirring will become difficult. In addition, if the temperature is higher than the above range, the water produced by the polymerization reaction will evaporate rapidly, and the area near the liquid surface will become foamy, making it difficult to adjust the liquid level, and furthermore, during the first polymerization process. The temperature of the gas phase inside the tank becomes too high, causing problems as described below. That is, the temperature of the gas phase in the first polymerization tank is
It is preferable to maintain the temperature within the range of 190 to 200°C, and if the temperature of the gas phase is higher than the above range,
Since 12-aminododecanoic acid melts near the monomer supply port 2 and adheres to the vessel wall, the monomer supply port 2
Moreover, there arises a drawback that the tendency to block the exhaust port 3 increases. Additionally, if the temperature of the gas phase is lower than the above range, the melting of powdered 12-aminododecanoic acid at the liquid surface of the liquid phase will be slow, making smooth stirring difficult as described above. A problem arises. The polymerization reaction of 12-aminododecanoic acid is 0.5Kg/cm ²
(gauge pressure) or less. In particular, the pressure in the gas phase is 0 to 1000 mmH ₂ O (gauge pressure), especially 3
It is preferable to maintain the pressure within the range of 500 mmH ₂ O (gauge pressure). If the pressure in the gas phase is lower than the above range, there is a risk of air infiltration from poorly sealed parts such as flange parts and open pipes. Moreover, if it is higher than the above range, it becomes difficult to supply 12-aminododecanoic acid smoothly. In the upper layer of the contents in the first polymerization tank, the content of monomers and low polymers is high, so a large amount of water is produced as a by-product during the polycondensation reaction, and this water cannot be efficiently used. Although it is necessary to remove the stirring blade 11
is located between each heating plate 8,
Stirring efficiency is also increased, and water can be removed efficiently. The prepolymerization product taken out from the prepolymerization product outlet 4 is transferred through the polymer transfer pipe 40 by a gear pump 41, and is continuously transferred in a molten state from the prepolymerization product supply port 31 to the second polymerization product. It is sent into the tank 30. At this time, a heating jacket is provided around the polymer transfer pipe 40 and the gear pump 41 to prevent the temperature of the prepolymerized product from decreasing during transfer. The prepolymerization product has a relative viscosity of 1.35 to 2.20 and a number average molecular weight generally of 5000 to 20000. It may be possible to produce high-molecular-weight nylon-12 in the first polymerization tank alone by changing the polymerization conditions, but in reality, it is possible to produce nylon-12 with a high molecular weight in the first polymerization tank alone. The polymerization hardly progresses, and it is difficult to obtain high molecular weight nylon-12 using only the first polymerization tank. In the present invention, nylon-12 having a higher molecular weight can be produced by supplying the prepolymerization product to the second polymerization tank and further postpolymerizing it. A viscosity stabilizer supplied from a viscosity stabilizer supply tank is mixed into the prepolymerized product being transferred within the polymer transfer pipe 40 by a gear pump 45 . The viscosity stabilizer used in the present invention includes:
One or two selected from the group consisting of monocarboxylic acids, dicarboxylic acids, monoamines, and diamines
More than one species of compounds can be mentioned. Examples of the carboxylic acid include monocarboxylic acid derivatives of aliphatic or aromatic hydrocarbons having 1 to 20 carbon atoms, such as acetic acid, propionic acid, butyric acid, caproic acid, stearic acid, benzoic acid, and the like. Examples of dicarboxylic acids include adipic acid,
6 carbon atoms such as sebacic acid, dodecanedioic acid, etc.
Examples include dicarboxylic acid derivatives of aliphatic or aromatic hydrocarbons having 1 to 12 aliphatic or aromatic hydrocarbons. Examples of monoamines include methylamine,
1 to 12 carbon atoms such as ethylamine, hexylamine, octylamine, laurylamine, etc.
Examples include monoamine derivatives of aliphatic hydrocarbons having . Examples of the diamine include diamine derivatives of aliphatic or aromatic hydrocarbons having 6 to 8 carbon atoms, such as hexamethylene diamine, nonamethylene diamine, metaxylylene diamine, and paraxylylene diamine. Adding and mixing the above viscosity stabilizer into the prepolymerization product,
By subsequently performing post-polymerization, the polymerization reaction can be performed extremely stably and with good reproducibility.Furthermore, by changing the amount of viscosity stabilizer added, the molecular weight (specific viscosity) of the resulting nylon-12 can be controlled over a wide range. can be changed arbitrarily. That is, when the addition ratio of the viscosity stabilizer is increased, the molecular weight of the polymer becomes smaller, and when the addition ratio is reduced, the molecular weight of the polymer becomes larger. The relationship between the addition ratio of the viscosity stabilizer to the prepolymerization product and the molecular weight of nylon-12 cannot be clearly defined because it depends on the molecular weight of the prepolymerization product and the polymerization conditions during postpolymerization. However, if the number average molecular weight of the prepolymerized product is approximately 5000 or less,
20000, the amount of viscosity stabilizer added is generally
By changing the amount within the range of 1/90 to 1/5000 mol per mol of the structural unit of the prepolymerization product,
The relative viscosity of nylon-12 can be adjusted as desired within the range of 1.9 to 3.5 (corresponding to a number average molecular weight of 14,700 to 43,200). If the addition ratio of the viscosity stabilizer is lower than the above range, nylon with a relative viscosity higher than the above range
12 is obtained, but the relative viscosity varies greatly during continuous operation, resulting in a homogeneous nylon-
It becomes difficult to stably manufacture 12. Also,
If the addition ratio of the viscosity stabilizer is larger than the above range, the relative viscosity of the produced nylon-12 will not increase much, making it impossible to obtain high molecular weight nylon-12. The stirring blade 39 in the second polymerization tank is connected to the stirring shaft 38
Due to the rotation of
It is necessary that the shape has the function of being moved to the 2 side and being stirred and mixed in a plane direction perpendicular to the stirring shaft 38. As the stirring blade, any shape can be used as long as it has such a function. Further, it is necessary to provide the stirrer so that the tip of the stirrer 39 is as close as possible to the inner wall surface of the lower part of the second polymerization tank. The tip of the stirring blade 39 and the second
If the distance between the lower part of the polymerization tank 30 and the inner wall surface is large,
Since the polymer in the vicinity of the inner wall surface is difficult to move, it undergoes a long thermal history and gradually undergoes thermal deterioration, and this deteriorated nylon-12 is mixed into the produced polymer, resulting in a decrease in quality. Thus, the prepolymerization product supplied from the prepolymerization product supply port 31 moves in the polymerization tank in a molten state to the discharge port 32 side while being stirred by the stirring blade, and during this time, polymerization further progresses. The molecular weight increases and is extracted as high molecular weight nylon-12. The amount of polymer in the second polymerization tank is preferably such that it occupies 30 to 60% of the internal volume of the polymerization tank, and the temperature inside the polymerization tank is 200 to 280°C, especially 230°C.
It is preferable to maintain the temperature within the range of 270°C to 270°C. Further, it is preferable to proceed with the post-polymerization while forcibly removing water produced as a by-product during the post-polymerization. Then, an inert gas such as dry nitrogen gas is supplied from the inert gas supply port 35 and is circulated through the head space to be removed from the system through the exhaust port 36 along with the water vapor generated from the liquid phase. Alternatively, a method may be applied in which by-product water is removed from the system through the exhaust port by bringing the head space into a reduced pressure state with or without supplying dry inert gas. As the inert gas, dry nitrogen gas is most advantageously used;
It is preferable that the water content per 1Nm ³ is 0.1g or less.
Further, the amount of inert gas supplied can be adjusted as appropriate depending on the amount of water produced as a by-product, but it is generally preferably 0.03 m ³ or less per 1 kg of prepolymerization product in terms of standard conditions. In the method of depressurizing the head space described above, the absolute pressure of the head space is reduced to 100 to 600 mm.
Hg, preferably in the range of 200 to 400 mmHg, by connecting a suitable exhaust pump or vacuum pump (not shown) to the exhaust port 36. It can be done easily. If the pressure in the head space is lower than the above range, water evaporation will be too rapid, which may cause a local temperature drop in the polymer, while if it is higher than the above range, the water removal efficiency will be reduced. Due to the action of the stirring blades 39, the water produced as a by-product as the polymerization reaction progresses is extremely smoothly transferred from the viscous liquid phase to the gas phase (head space), and the water evaporates only locally. Because the polymer spreads over the entire interface of the liquid phase, the temperature of the polymer does not locally decrease due to the latent heat of vaporization of water, and a homogeneous polymer can be obtained. The residence time of the polymer in the second polymerization tank is preferably 2 to 8 hours. (Effects of the Invention) The method of the present invention combines a first step in which prepolymerization is performed in a first polymerization tank and a second step in which postpolymerization is performed in a second polymerization tank, and the polymerization conditions in each polymerization step are adjusted. By specifying and further post-polymerizing the prepolymerization product with the addition of a viscosity stabilizer, nylon-12 with a high molecular weight controlled within a desired narrow range is produced in a stable state over a long period of time. In addition, the polymerization time, especially the polymerization time in the second step, can be shortened, and since the polymer does not stay locally in the polymerization tank for a long time, it is subjected to a long thermal history. This has the excellent effect of producing stable, high-quality nylon-12 without contaminating the product with degraded polymers. (Examples) Examples 1 to 5 Using a 12-aminododecanoic acid continuous polymerization apparatus as shown in FIG. 1, two-stage continuous polymerization of 12-aminododecanoic acid was carried out. The first polymerization tank 1 has an inner diameter of 1.15 m, an inner height of 3.8 m, an inner volume of 2.9 ^m3 , and a heating plate 8.
The thickness of is 0.5cm, the vertical width is 50cm,
The stirring blades 11 were comb-shaped, and the length of the portion overlapping the heating plate was 25 cm. The second polymerization tank 30 has an inner diameter of 0.61 m and an inner length of 1.75 m, and the stirrer is a glasses-shaped stirring blade.
It had 20 pieces. While maintaining the contents of the first polymerization tank at approximately 1.9 ^m3 so that the liquid level was approximately 10 cm above the upper end of the heating plate, the heating jacket and heating plate were heated to a temperature of approximately 230°C. Circulate the oil and turn on the agitator
Rotated at 6r.pm. Powdered 12-aminododecanoic acid is fed from the monomer feed port 2 at a feed rate commensurate with the amount of prepolymer discharged.
The first polymerization tank was continuously charged with nitrogen gas of 2 Nm ³ per hour. The temperature of the gas phase of the first polymerization tank is
The temperature is 190℃, the pressure is 10mmAq.G, and the temperature of the liquid phase (contents) is 210℃ at the top, 230℃ at the center, and 230℃ at the bottom.
The temperature was maintained at 240°C. Residence time in the first polymerization tank is approx.
12-aminododecanoic acid is polycondensed for 4.8 hours, and the prepolymerization product is taken out at a predetermined rate per hour by adjusting the rotation speed of the gear pump 41 from the prepolymerization product outlet. Ta. The number average molecular weight of the prepolymerization product is 10600 (relative viscosity
1.67) The water content was 0.4% by weight and the melting point was 176°C. The prepolymerization product is supplied to the second polymerization tank 30 via the transfer pipe 40 at the same rate as the discharge rate, and at the same time stearic acid in a molten state from the viscosity stabilizer tank 43 is stabilized in viscosity by a gear pump 45. The agent was mixed into the prepolymerization product through the supply pipe 44 at a rate of 1/1800 mole per mole of the structural unit of the prepolymerization product being transferred through the transfer pipe 40 . The amount of polymer in the second polymerization tank was adjusted to maintain the residence times shown in Table 1. A heating medium was passed through the heating jackets 37 and 42 to adjust the temperature near the prepolymerization product supply port and the nylon-12 discharge port in the second polymerization tank to the temperatures shown in Table 1. . In the gas phase (head space) of the second polymerization tank,
Dry nitrogen gas is supplied from the inert gas supply port 35 at a rate shown in Table 1, and while nitrogen gas and water vapor are removed from the exhaust port 36, the pressure in the gas phase is reduced to 20 mm.
Maintained in _H2OG . The stirrer 38 of the second polymerization tank 30 was rotated at 8 rpm. supply rate of the prepolymerization product to the second polymerization tank 30;
Residence time of the polymer in the second polymerization tank, temperature of the polymer at the above location in the second polymerization tank, rate of supply of nitrogen gas to the gas phase of the second polymerization tank, relative viscosity of the obtained nylon-12 , the amount of terminal amino groups and the melting point are shown in Table 1. The method for measuring relative viscosity is as follows. Relative viscosity measurement method (based on JIS K 6810) 1 Sample (prepolymerization product or nylon 12) approx.
Accurately weigh 250mg to 0.1mg and transfer to a 100ml stoppered flask. 2 Next, add 98% sulfuric acid to a concentration of 1g/100ml. 3. Add a rotor and stir using a magnetic stirrer for at least 4 hours to completely dissolve. 4 After 6 hours, measure the solubility with a 15 ml pipette and transfer to a Canon Fuenske viscometer. 5 Place in a constant temperature water bath adjusted to 20±0.05℃ and leave for 30 minutes. 6. Measure the number of seconds required for the flow to flow between the upper and lower marked lines of the viscosity tube three times using a stopwatch, and take the average value. 7 Similarly, measure the number of seconds required for the solvent sulfuric acid. 8 Find the relative viscosity using the following equation. Relative viscosity = number of seconds for sample solution to flow/number of seconds for 98% sulfuric acid to flow

[Table] Examples 6 to 12 The stearic acid feed rate was changed as shown in Table 2, and the residence time, polymer temperature, and nitrogen gas feed rate were changed as shown in Table 2.
In the same manner as in Example 1, 12-aminododecanoic acid was polymerized to produce nylon-12. The properties of the obtained nylon-12 are shown in Table 2.

[Table] Example 13 The procedure was the same as in Example 1, except that laurylamine was used in the amount shown in Table 3 instead of stearic acid, and the polymerization conditions in the second step were changed as shown in Table 3. , 12-aminododecanoic acid was polymerized to produce nylon-12. The properties of the obtained nylon-12 are shown in Table 3.

[Table] Example 14 The procedure was the same as in Example 1, except that adipic acid was used in the amount shown in Table 4 instead of stearic acid, and the polymerization conditions of the second step were changed as shown in Table 4. , 12-aminododecanoic acid was polymerized to produce nylon-12. The properties of the obtained nylon-12 are shown in Table 4.

[Table] Example 15 In Example 1, the supply rate of the prepolymerization product to the second polymerization tank was set to 210 Kg/hr, the residence time of the polymer in the second polymerization tank was set to 4.0 hours, and the second polymerization tank was The temperature near the polymer inlet and outlet in
The pressure in the gas phase of the second polymerization tank was set to 248℃ and 263℃.
Nylon-12 was produced in the same manner as in Example 1, except that the nitrogen gas supply rate to the second polymerization tank was changed to 200 mmHg (absolute pressure) and 0.2 Nm ³ /hr. The relative viscosity of the obtained nylon-12 was 3.21, and the terminal amino group was 2.26×10 ⁻⁵ eq/g. Examples 16 to 19 In the second step, the stearic acid supply rate, prepolymerization product supply rate, residence time, and polymer temperature were changed as shown in Table 5, and the pressure in the gas phase was adjusted.
Nylon-12 was produced in the same manner as in Example 15, except that the pressure was changed to 400 mmHg (absolute pressure). Table 5 shows the relative viscosity and terminal amino group content of the obtained nylon-12.

【table】 [Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of an example of the continuous polymerization apparatus of the present invention used to carry out the continuous polymerization method of the present invention, and FIG. 2 is a cross-sectional view taken along line A-A in FIG. FIG. 3 is a sectional view taken along line B-B in FIG.
FIG. 4 is a sectional view of another example of the second polymerization tank, and FIG. 5 is a diagram showing the relationship between the amount of viscosity stabilizer (stearic acid) added and the viscosity of nylon-12. 1 is a first polymerization tank, 2 is a monomer supply port, 3 is an exhaust port, 4 is a prepolymerization product discharge port, 5 is a heating jacket, 6 is a heater, 7 is a heat medium flow path, and 8 is a heating plate, 9 is a heat medium supply pipe, 10 is a heat medium discharge pipe, 11 is a stirring blade, 12 is a rotary stirrer, 13 is a stirring arm, 14 is a monomer metering feeder, 15 is an inert gas supply pipe, 16 is a inert gas metering feeder,
17 is a monomer supply pipe, 30 is a second polymerization tank, 31 is a prepolymerization product supply port, 32 is a nylon-12 discharge port, 34 is a screw extractor, 35 is an inert gas supply port, and 36 is a discharge port. Outlet, 37 is a heating jacket, 38 is a stirring shaft, 39 is a stirring blade, 40 is a polymer transfer pipe, 41 is a gear pump, 42 is a heating jacket, 43 is a viscosity stabilizer tank, 44 is a viscosity stabilizer supply pipe, 45 is a gear pump, 46 is a heating jacket, 47 is a melt filling section in the second polymerization tank, and 48 is a head space formed above the melt filling section.

Claims (1)

[Claims] 1. 12-Aminododecanoic acid is prepolymerized in a first polymerization tank to obtain a prepolymerized product having a relative viscosity of 1.35 to 2.20 measured at 25°C at a concentration of 1 g/100 ml in 98% sulfuric acid. The first step of manufacturing is to mix a viscosity stabilizer into the pre-polymerized product and post-polymerize it in a second polymerization tank so that the relative viscosity is between 1.9 and 1.9.
2 of 12-aminododecanoic acid, characterized in that it consists of a second step of producing nylon-12 of 3.5.
Step polymerization method. 2. The method according to claim 1, wherein the viscosity stabilizer is one or more compounds selected from the group consisting of monocarboxylic acids, dicarboxylic acids, monoamines, and diamines. 3. The method according to claim 1, wherein the viscosity stabilizer is added in an amount ranging from 1/90 to 1/5000 mole per mole of structural unit of the prepolymerized product. 4. A method as claimed in claim 1, characterized in that the second polymerization tank is of horizontal configuration and has a head space above the melt filling. 5. The method according to claim 1, wherein the polymerization is carried out while forcibly removing by-product water from the system in the post-polymerization step. 6. The method according to claim 5, characterized in that the pressure of the gas phase in the second polymerization tank is reduced to below normal pressure. 7. The method according to claim 5, characterized in that a dry inert gas is passed through the gas phase in the second polymerization tank. 8. The method according to claim 7, wherein the inert gas is dry nitrogen gas.