JP2016141698A - Method for producing dehydration polycondensation polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide, in a production method of a dehydration polycondensation polymer comprising a step of subjecting a prepolymer to dehydration polycondensation in an extruder having (a) vent portion(s), a production method having good production efficiency while suppressing vent-up.SOLUTION: The method for producing a dehydration polycondensation polymer comprises a step of subjecting a prepolymer to dehydration polycondensation in an extruder having (a) vent portion(s), where R as defined by the following formula (1) is set at 2.50 or more and 4.50 or less. R=S+1.5×V1/V0 (1), where V0: an effective space volume [cm] of an extruder, V1: a total volume [cm] of a prepolymer, a polymer, and water vapor contained therein inside the extruder, and S: a distilling rate per unit area [mg/(cm×sec)] of condensed water from a fore vent portion.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method for producing a dehydrated polycondensation polymer. More specifically, the present invention relates to a method for producing a dehydrated polycondensation polymer having a step of dehydrating polycondensation of a prepolymer with an extruder having a vent portion.

  A dehydration polycondensation polymer is generally produced by heating one or more raw material monomers to advance polymerization and removing condensed water. For example, in the case of polyamide, which is a kind of dehydration polycondensation polymer, a raw material monomer is reacted in a solvent such as water to form a salt solution, and then the salt solution is heated to evaporate the solvent and concentrate to a specified concentration. To obtain a mixture of the prepolymer and the solvent. Thereafter, a method is known in which the mixed liquid is transferred to a reactor and further heated to advance the polymerization and to evaporate the solvent remaining after concentration and the condensed water generated by the polymerization to obtain polyamide.

  However, in the method as described above, since the mixture of the prepolymer and the solvent stays in the reactor for a long time under high temperature conditions, gelation and thermal degradation are likely to occur, and the resulting polymer It tends to cause quality degradation. Therefore, a production method in which a low-order condensate is taken out in a solid state, kneaded in a molten state to form a prepolymer, and then polymerized in a solid state is disclosed (for example, see Patent Document 1). However, in such a process combining melt polymerization and solid phase polymerization, the facilities become complicated and inconvenience in maintenance becomes a problem.

  Then, the manufacturing method which carries out the dehydration polycondensation of the polycondensation type polymer using an extruder is disclosed (for example, refer patent documents 2-3).

Japanese Patent Laid-Open No. 61-228022 JP 2010-53359 A International Publication No. 2013/190629

  In the production methods disclosed in Patent Documents 2 to 3, in order to advance dehydration polycondensation of the prepolymer with an extruder, it is necessary to deaerate condensed distilled water from the extruder vent. However, when the condensed distillate water is degassed from the vent portion, a trouble (vent up) in which the prepolymer or the polymer is accompanied to block the vent portion may occur. When vent-up occurs, the vent part closes and condensation water cannot be removed from the system, so the progress of the polymerization reaction is suppressed due to the equilibrium of the reaction, and the target polymer cannot be obtained, causing trouble. Until the problem is solved, it is necessary to discard the obtained polymer or to stop the equipment, and there is a problem that the production efficiency is lowered. On the other hand, in order not to cause vent-up, it is effective to reduce the production amount, but there is still a problem that the production efficiency is lowered.

  An object of the present invention is to provide a method for producing a dehydrated polycondensation polymer having a step of dehydrating polycondensation of a prepolymer with an extruder having a vent part, while suppressing the vent-up and providing a production method with high production efficiency. And

In order to solve the above problems, the present invention employs one of the following configurations.
(1) A method for producing a dehydrated polycondensation polymer comprising a step of dehydrating polycondensation of a prepolymer with an extruder having a vent part, wherein R defined by the following formula (1) is 2.5 or more and 4.5 A method for producing a dehydrated polycondensation polymer as described below.
R = S + 1.5 × V1 / V0 (1)
V0: Effective space capacity in the extruder [cm ³ ]
V1: Total capacity [cm ³ ] of prepolymer, polymer, and water vapor contained in the extruder
S: Condensed water distillation rate per unit area from fore vent part [mg / (cm ² × sec)]
(2) The method for producing a dehydrated polycondensation polymer according to (1), wherein the dehydration polycondensation polymer is polyamide.
(3) The manufacturing method of the dehydration polycondensation polymer in any one of (1)-(2) whose relative viscosity of the said prepolymer is 1.38 or less.
(4) The method for producing a dehydration polycondensation polymer according to any one of (1) to (3), wherein the prepolymer is supplied to an extruder in a molten state.
(5) The method for producing a dehydration polycondensation polymer according to any one of (1) to (4), wherein the pressure of the vent portion is less than atmospheric pressure.
(6) The method for producing a dehydration polycondensation polymer according to any one of (1) to (5), wherein R is 2.5 or more and 4.0 or less.
(7) The method for producing a dehydration polycondensation polymer according to any one of (1) to (6), wherein R is 2.5 or more and 3.7 or less.
(8) The method according to any one of (1) to (7), including a step of polycondensing a polyamide precursor under pressure in a prepolymerization tank to obtain a prepolymer before the step of dehydrating and polycondensing the prepolymer. A method for producing a dehydrated polycondensation polymer.

  According to the method of the present invention, it is possible to grasp the vent-up suppression conditions in the extruder, and to provide a manufacturing method with good production efficiency while suppressing the vent-up.

It is the schematic which shows the manufacturing apparatus of polyamide. It is a conceptual diagram of extruder operation conditions.

  Hereinafter, an embodiment of the method for producing a dehydrated polycondensation polymer of the present invention will be described in detail.

  In the present invention, the dehydrated polycondensation polymer is a polymer produced by removing condensed water while polymerizing one or more raw material monomers, and examples thereof include polyamide, polyester, and polycarbonate. Among these, the manufacturing method of the dehydration polycondensation polymer of this invention is used suitably as a manufacturing method of polyamide.

  Examples of the polyamide production method include a step of polycondensing a polyamide precursor under pressure in a prepolymerization tank to obtain a prepolymer, and a step of dehydrating polycondensation of the prepolymer with an extruder having a vent portion. Is mentioned. Here, the polyamide precursor is supplied to a prepolymerization tank described later, and examples thereof include a salt of a dicarboxylic acid and a diamine, a lactam, and a ring-opened product thereof. If necessary, the polyamide precursor may further contain water and additives such as a polymerization degree regulator and a polymerization catalyst described later. Moreover, as a polyamide precursor, you may contain the polymer of dicarboxylic acid and diamine whose relative viscosity (eta) r is 1.3 or less, Preferably it is about 1.1 or less.

  In order to produce the polyamide precursor, for example, dicarboxylic acid and diamine, lactam, a ring-opened product thereof, and water and additives as necessary are used as raw materials. These are mixed and heat-treated, and the raw material is dissolved to cause a salt reaction or a partial polycondensation reaction to obtain a polyamide precursor. Hereinafter, these dicarboxylic acids, diamines, lactams, ring-opened products thereof, and water and additive mixtures used as necessary before heat treatment are referred to as “raw materials”.

  In the present invention, the dicarboxylic acid, diamine, lactam, and ring-opened product thereof may be any one that forms an amide unit constituting the polyamide.

  The dicarboxylic acid is preferably one having 2 to 18 carbon atoms, for example, adipic acid, sebacic acid, malonic acid, succinic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, undecanedioic acid, dodecanedioic acid, tetradecane. Examples thereof include aliphatic dicarboxylic acids such as diacid, pentadecanedioic acid, and octadecanedioic acid, and aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid. Two or more of these may be used. As the dicarboxylic acid, adipic acid, sebacic acid, terephthalic acid and isophthalic acid are more preferable, and adipic acid, sebacic acid and terephthalic acid are more preferable.

  The diamine is preferably one having 4 to 14 carbon atoms, such as hexamethylenediamine (1,6-diaminohexane), 1,4-diaminobutane, 1,5-diaminopentane, 1,7-diaminoheptane, 1 , 8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane, 1,12-diaminododecane, 1,13-diaminotridecane, 1,14-diaminotetradecane, etc. Group diamine and the like. Two or more of these may be used. Among the above, hexamethylenediamine, 1,4-diaminobutane and pentamethylenediamine are more preferable, and hexamethylenediamine and 1,4-diaminobutane are more preferable.

  Preferred combinations of dicarboxylic acid and diamine include (i) terephthalic acid, adipic acid and hexamethylene diamine, (ii) isophthalic acid, adipic acid and hexamethylene diamine, (iii) sebacic acid and hexamethylene diamine, (iv) sebacin Examples include acid and 1,4-diaminobutane, (v) adipic acid and hexamethylenediamine, and (vi) terephthalic acid and 1,10-diaminodecane.

  Examples of the lactam include caprolactam and laurolactam. Two or more of these may be used.

  In producing the polyamide precursor, it is preferable that the moisture content of the polyamide precursor is 50% by mass or less. The water content here means mass% of water in the total polyamide precursor including dicarboxylic acid, diamine, aminocarboxylic acid, lactam and water and additives used as necessary. By making the moisture content of the polyamide precursor 50% by mass or less, energy efficiency can be improved when a polyamide is produced using the polyamide precursor. From the viewpoint of energy efficiency, the amount of water in the polyamide precursor is preferably as small as possible. On the other hand, the amount of water in the polyamide precursor is preferably 10% by mass or more and more preferably 15% by mass or more from the viewpoint of heating and dissolving the polyamide precursor at a lower temperature and suppressing an undesirable polymerization reaction.

  The pressure at the time of heating and melting the raw material is preferably set to atmospheric pressure or higher in order to prevent polymerization of the raw material. The pressure at the time of dissolution by heating refers to the pressure in the dissolution tank at that time, and in a closed system, is determined by the water vapor pressure at the time of dissolution equilibrium indicated by the raw material containing water. Therefore, this pressure can be appropriately adjusted depending on, for example, the amount of water contained in the raw material of the polyamide precursor and the heating temperature. Moreover, you may further pressurize by inert gas, such as nitrogen, as needed.

  There is no restriction | limiting in particular as an apparatus which heat-dissolves the said raw material, A batch-type or continuous-type reaction kettle provided with the conventionally well-known heating apparatus can be used. It is preferable to have a stirrer so that the raw materials can be stirred during heating and melting.

  In addition, when the raw material is heated and dissolved, it is preferable to remove oxygen from the raw material tank or the heating device before starting heating for the purpose of preventing coloring and deterioration due to oxygen. The method for removing oxygen is not particularly limited. Oxygen can be removed by a known method such as a batch-type vacuum and replacement with an inert gas such as nitrogen, or a method of blowing an inert gas such as nitrogen. That's fine.

  Next, a method for producing a polyamide from the polyamide precursor obtained by the above method will be described. FIG. 1 shows a schematic diagram of a polyamide production apparatus preferably used in the present invention. For example, a polyamide prepolymer (hereinafter referred to as “prepolymer”) is obtained by continuously polycondensing a polyamide precursor in a prepolymerization tank 1c using the polyamide polymerization apparatus shown in FIG. Polyamide is obtained by continuously increasing the degree of polymerization in the extruder 1d.

  In order to obtain the prepolymer continuously, it is preferable to continuously supply the polyamide precursor to the prepolymerization tank. When the raw material of the polyamide precursor is heated and dissolved using the batch type heating and dissolving apparatus 1a, it is preferable to provide a buffer tank 1b between the batch type heating and dissolving apparatus 1a and the prepolymerization tank 1c. In addition, below, the aspect which provides the buffer tank 1b is demonstrated in detail.

  The polyamide precursor obtained by heating and dissolving is sent to a buffer tank 1b located on the downstream side of the heating and dissolving apparatus 1a. The method for sending the polyamide precursor from the heating and dissolving apparatus to the buffer tank 1b is not particularly limited, and it is sent by its own weight by a conventionally known pumping method or by holding the heating and dissolving apparatus 1a and the buffer tank 1b at a uniform pressure. The method etc. are mentioned. The polyamide precursor sent to the buffer tank 1b stays in the buffer tank 1b until it is supplied to the prepolymerization tank 1c located further downstream of the buffer tank 1b. Therefore, the temperature of the buffer tank 1b is preferably set to 200 ° C. or lower. If the temperature of the buffer tank 1b is 200 degrees C or less, the progress of the polymerization reaction during residence can be suppressed and the supply stability of the polyamide precursor can be kept high. On the other hand, in order to suppress the precipitation of the polyamide precursor, the temperature of the buffer tank 1b is preferably 100 ° C. or higher, and more preferably 110 ° C. or higher.

  The pressure in the buffer tank 1b is the pressure in the buffer tank 1b when the polyamide precursor is retained, and is mainly determined by the amount of water in the polyamide precursor and the temperature of the buffer tank 1b. Therefore, this pressure can be appropriately adjusted depending on, for example, the amount of water contained in the polyamide precursor and the temperature of the buffer tank 1b. Moreover, you may further pressurize by inert gas, such as nitrogen, as needed.

  The polyamide precursor staying in the buffer tank 1b is continuously supplied to the prepolymerization tank 1c located downstream of the buffer tank 1b using a pump capable of supplying a fixed amount. The polyamide precursor is continuously polymerized into the prepolymer inside the prepolymerization tank 1c. The prepolymer referred to here is obtained by a polymerization reaction of a polyamide precursor, and refers to a mixture containing an oligomer, an unreacted monomer, water and condensed water produced by the polymerization reaction.

  The relative viscosity (ηr) of the prepolymer obtained here is usually 1.1 to 2.0. In order to increase the degree of polymerization in the next step, the relative viscosity of the prepolymer is preferably 1.2 or more. On the other hand, the relative viscosity of the prepolymer is preferably 1.9 or less, more preferably 1.8 or less, and even more preferably 1.38 or less in order to suppress the formation of a gelled product in the prepolymerization tank 1c due to abnormal residence. Here, the relative viscosity (ηr) of the prepolymer is a value measured by dissolving the prepolymer in 98% sulfuric acid at a concentration of 0.01 g / ml according to JIS K6810 (1994) and using an Ostwald viscometer at 25 ° C. It is.

  The reaction temperature (the temperature inside the prepolymerization tank 1c) when producing the prepolymer is usually the melting point of the finally obtained polyamide of −50 to + 10 ° C. In order to shorten the reaction time, the reaction temperature is preferably (melting point−40 ° C.) or higher, more preferably (melting point−30 ° C.) or higher. On the other hand, in order to suppress thermal decomposition and the formation of a gelled product, the reaction temperature is preferably the melting point or lower, more preferably (melting point−10 ° C.) or lower.

  The pressure at the time of producing the prepolymer (the pressure inside the prepolymerization tank 1c) is usually operated to be kept at 0 to 4 MPa-G, preferably 0.3 to 3.5 MPa-G. Here, the pressure unit MPa-G means a pressure (gauge pressure) expressed using the atmospheric pressure as a reference (zero), and indicates a pressure difference [MPa] between the absolute pressure and the atmospheric pressure. The pressure is preferably low from the viewpoint of the supply accuracy of the polyamide precursor and the equipment cost.

  The reaction time when producing the prepolymer is usually 10 to 120 minutes. In order to facilitate higher polymerization and composition adjustment in the next step, the reaction time is preferably 30 minutes or more. On the other hand, the reaction time is preferably 100 minutes or less in order to suppress thermal decomposition, gelation product formation, and abnormal retention.

  Although there is no restriction | limiting in particular as the prepolymerization tank 1c, The prepolymerization tank 1c which divided the inside with the perforated board etc. by the cylindrical shape is preferably used so that an unnecessary convection may not occur. In the prepolymerization tank 1c, a rectification tower or the like can be installed in the upper part of the prepolymerization tank so that the composition ratio does not shift due to the diamine being distilled with water during pressure adjustment, thereby preventing the diamine from being distilled.

  In order to facilitate the adjustment of the polymerization degree in the production of the prepolymer, it is effective to add a polymerization degree regulator, and the polymerization degree regulator can be added to the heating and dissolving apparatus during the production of the polyamide precursor. Examples of the polymerization degree modifier include organic acids and / or organic bases, and two or more of these may be used. As the organic acid, for example, benzoic acid, acetic acid, stearic acid and the like are preferable, and benzoic acid is more preferable. Moreover, as an organic base, a C4-C14 aliphatic diamine is preferable. The addition amount of the polymerization degree modifier is preferably 0 to 0.1 times mol, and 0.0001 to 0.05 times mol for the total number of moles of dicarboxylic acid, diamine, lactam, and ring-opened product thereof. More preferred.

  A phosphoric acid catalyst can also be used in the production of the prepolymer. The phosphoric acid catalyst may be added to the heating / dissolving apparatus 1a during the production of the polyamide precursor, or may be added to the prepolymerization tank 1c. The phosphoric acid catalyst has a catalytic function for the polymerization reaction.

  Specific examples of the phosphoric acid catalyst include phosphoric acid, phosphate, hypophosphite, acidic phosphate ester, phosphate ester, and phosphite ester, and two or more of these may be used. . Of these, hypophosphite is preferable, and sodium hypophosphite is more preferable.

  When adding a phosphoric acid catalyst, 0.001-5 mass parts is preferable with respect to 100 mass parts of prepolymers, and, as for the addition amount, 0.01-1 mass part is more preferable.

  Next, the process of dehydrating and polycondensing the prepolymer with an extruder having a vent part will be described. The prepolymer obtained in the prepolymerization tank is supplied to an extruder and melted and kneaded in the extruder, whereby a dehydration polycondensation reaction proceeds to become a polymer. In addition, as a method for supplying the prepolymer to the extruder, the prepolymer discharged from the prepolymerization tank is charged into the feeder of the extruder and supplied to the extruder in a solid state, or in a molten state from the prepolymerization tank. The method of supplying directly to an extruder is mentioned. Since it is not necessary to remelt the prepolymer and the load applied to the extruder can be reduced, a method of directly feeding the prepolymer in a molten state from the prepolymerization tank is preferable.

  The extruder has a vent part, and discharges the condensed distillate out of the system. The number of vent portions is not particularly limited as long as it is one or more, and has a vent port (rear vent) 1e installed behind the supply port of the extruder and a vent port (fore vent) 1f installed in front of the supply port. It is preferable. By having a rear vent and fore vent, water that evaporates when the prepolymer is supplied, water generated by the polymerization reaction of the prepolymer, and a very small amount of unreacted monomer can be discharged more efficiently outside the system. Thus, a polyamide having a high degree of polymerization can be easily produced. Although there is no restriction | limiting in particular in the pressure of a vent part, It is preferable to deaerate below atmospheric pressure using well-known pressure reduction and vacuum apparatuses, such as a Nash pump.

  In the present invention, the prepolymer tank 1c for producing the prepolymer is not particularly limited, but the extruder 1d provided on the downstream side thereof is preferably a twin screw extruder having self-cleaning properties.

  The prepolymer supplied to the extruder 1d is usually melt-kneaded in the range of the melting point of the finally obtained polymer + 5 to + 40 ° C., preferably in the range of (melting point + 10 ° C.) to (melting point + 40 ° C.). It becomes a polymer by dehydration polycondensation reaction. In order to increase the polymerization reaction rate, the melt kneading temperature is preferably (melting point + 5 ° C.) or higher. Further, the temperature is preferably (melting point + 40 ° C.) or lower in order to prevent thermal decomposition and generation of gelled product. Here, the melting point of the polymer refers to a temperature indicating the maximum value of the melting curve obtained by measurement at a heating rate of 20 ° C./min by the DSC method.

At this time, in the present invention, R defined by the following formula (1) is 2.5 or more and 4.5 or less. If R is less than 2.5, the production efficiency is lowered. On the other hand, if R exceeds 4.5, vent-up is likely to occur, and production efficiency decreases. R is preferably 4.0 or less, and more preferably 3.7 or less.
R = S + 1.5 × V1 / V0 (1)
V0: Effective space capacity in the extruder [cm ³ ]
V1: Total capacity [cm ³ ] of prepolymer, polymer, and water vapor contained in the extruder
S: Condensed water distillation rate per unit area from fore vent part [mg / (cm ² × sec)]
The effective space capacity (V0) in the extruder is a value obtained by subtracting the capacity of the shaft and screw of the extruder from the volume of the extruder barrel space, and can be calculated from the drawing of the extruder.

  The total capacity (V1) of the prepolymer, polymer, and water vapor contained in the extruder is the sum of the polymer volume per unit time calculated from the polymer discharge rate and polymer density, and the resin. Is the total volume of water vapor contained in The resin here refers to a prepolymer and a mixture of polymers. The water vapor volume can be calculated from the polymer discharge amount multiplied by the moisture content contained in the resin. Since the moisture content in the resin depends on the polymer type and vent part pressure, a prepolymer with a known viscosity and carry-in moisture percentage is supplied to the extruder, and the polymer viscosity and distillation condensation are determined for each vent part pressure. By measuring the amount of water, the moisture content contained in the resin under each pressure condition can be calculated.

Further, the condensed water distilling rate per unit area (S) from the forevent part is the amount of distilled condensed water Q [mg / sec] degassed from the forevent part per unit time. It is a value (Q / A) divided by A [cm ² ]. The amount Q of distilled condensed water can be obtained by connecting a cooling condenser to the forevent part and measuring the condensed weight.

  As the polycondensation reaction of the prepolymer proceeds in the extruder, water (steam) is generated and degassed from the vent portion of the extruder. At this time, if the condensed water distillation rate (S) per unit area from the fore vent part is high, the prepolymer and the polymer are entrained in the water vapor, and the prepolymer and the polymer are lifted (bent up) in the fore vent part. It tends to happen. Moreover, if the filling rate (V1 / V0) in an extruder is high, the condensed water distillation speed | rate (S) per unit area of a for vent part which a vent up will generate | occur | produce will become low, and a vent up will generate | occur | produce easily. On the other hand, by reducing the discharge amount or suppressing the increase in the degree of polymerization, the condensation water distilling rate (S) per unit area of the fore vent portion can be lowered to suppress the occurrence of vent-up. Yes, but production efficiency will be reduced. In the present invention, paying attention to these relationships, as an index of the ease of venting up, the condensed water distillation rate S per unit area from the fore vent part, the filling rate (V1 / V0) in the extruder, and From the above, it has been found that by adjusting R calculated by the formula (1) to the above numerical range, vent-up can be suppressed while maintaining high production efficiency. Since it is possible to determine the ease of vent-up from the distilling line speed of the distilled condensed water and the filling rate of the extruder, a huge number of tests that individually change various conditions are performed, or more than necessary. Therefore, it is not necessary to keep the discharge amount low, and the vent-up can be suppressed, so that the production efficiency can be improved.

  A conceptual diagram of such extruder operating conditions is shown in FIG. In FIG. 2, the horizontal axis represents the filling rate (V1 / V0) in the extruder, and the vertical axis represents the condensed water distillation rate (S) per unit area from the forevent part. The R defined by the above formula (1) is 2.5 or more and 4.5 or less, that is, from the filling rate in the extruder and the fore vent part so as to be a region 2d filled with dots in FIG. By selecting the condensed water distillation rate per unit area, it is possible to improve production efficiency while suppressing vent-up.

  As a method of reducing the value of R, there are a method of reducing S and a method of reducing (V1 / V0). As a method for reducing S, for example, a method for increasing the degree of polymerization of the prepolymer supplied to the extruder, a method for decreasing the discharge amount, a method for decreasing the temperature of the extruder, a method for increasing the pressure in the forevent portion, etc. Is mentioned. On the other hand, as a method of decreasing (V1 / V0), a method of decreasing the discharge amount, a method of increasing the screw speed of the extruder, a method of lowering the extruder temperature, and a lower forevent portion pressure within an appropriate range. The method of doing is mentioned.

  In the present invention, the polymer residence time in the extruder 1d is not particularly limited, but is preferably 1 to 10 minutes in order to advance the polymerization to a sufficient viscosity as a polyamide and suppress thermal degradation and thermal decomposition due to residence for a long time. 1 to 5 minutes is more preferable.

  In addition, in any process such as a prepolymer production process or a prepolymerization degree increasing process, a catalyst, a heat stabilizer, a weather resistance stabilizer, an antioxidant, a plasticizer, a mold release agent, or a lubricant may be used as necessary. Crystal nucleating agents, pigments, dyes, other polymers, and the like can also be added.

  As mentioned above, although the manufacturing method of polyamide was mentioned as an example, about other dehydration polycondensation type polymers, such as polyester and polycarbonate, by making R into the above-mentioned range, with high production efficiency, suppressing vent-up. A polymer can be produced.

  The dehydrated polycondensation polymer obtained by the production method of the present invention can be formed into a molded product by an ordinary molding method as in the case of the conventional dehydration polycondensation polymer. The molding method is not particularly limited, and known molding methods such as injection molding, extrusion molding, blow molding, and press molding can be used. The molded product referred to here includes shaped products such as fibers, films, sheets, tubes, and monofilaments in addition to molded products by injection molding.

  Hereinafter, the present invention will be specifically described with reference to examples. In addition, the evaluation method of the characteristic described in the Example and the comparative example is as follows.

(1) Relative viscosity (ηr) of prepolymer and polymer
According to JIS K6810 (1994), a sample was dissolved in 98% sulfuric acid at a concentration of 0.01 g / ml and measured at 25 ° C. using an Ostwald viscometer.

(2) Filling rate in the extruder (V1 / V0)
The effective space capacity (V0) in the extruder was calculated from the drawing of the extruder. The total capacity (V1) of the prepolymer, polymer, and water vapor contained in the extruder is the sum of the polymer volume per unit time calculated from the polymer discharge rate and polymer density, and the resin. The total volume of water vapor contained. The water vapor volume contained in the resin is included in the resin in the polymer discharge amount using the value of the moisture content contained in the resin under each pressure condition calculated in advance using a prepolymer having a known viscosity and moisture content. Calculated from the product of the moisture content.

(3) Distilled condensed water amount The distilled condensed water amount Q was determined by connecting a cooling condenser to the vent part and measuring the condensed weight.

(4) Vent up The presence or absence of the rise of the resin from the fore vent port was visually observed. When the vent port was blocked with resin and the resin overflowed from the vent port, the vent was set up.

Example 1
A 350 L capacity dissolution tank having a stirrer and a jacket heating function was charged with 58.9 kg of hexamethylenediamine substantially free of water and 75.3 kg of water. Subsequently, 34.9 kg of adipic acid substantially free of water and 44.5 kg of terephthalic acid substantially free of water were charged, and nitrogen substitution was performed. Furthermore, sodium hypophosphite was added as a polymerization catalyst so as to be 0.05 parts by mass with respect to 100 parts by mass of the finally obtained polyamide. Moreover, benzoic acid was added as a polymerization degree regulator so that it might become 0.0133 times mole with respect to the total mole number of dicarboxylic acid and diamine. At this time, the water content with respect to the total charged amount was 35% by mass. And the dissolution tank was heated at 180 degreeC, and the water | moisture content in a system was evaporated and removed. Water was finally removed until the water content in the system reached 20% by mass to obtain a polyamide precursor.

  Subsequently, the polyamide precursor was pressure fed to the buffer tank by pressurizing the dissolution tank with nitrogen, and the residence temperature in the buffer tank was maintained at 160 ° C. The polyamide precursor obtained by the above method is continuously supplied to a 32 L vertical cylindrical prepolymerization tank by a plunger pump at a supply rate of 18.8 kg / hr, and the prepolymer is continuously polymerized under the conditions described in Table 1. did. Moreover, the prepolymer was sampled from the prepolymerization tank and the relative viscosity was measured. The obtained prepolymer was supplied by a gear pump to a twin-screw extruder (TEX-28V, manufactured by JSW) having a vent portion, and the degree of polymerization was increased under the conditions described in Table 1 to obtain polyamide 6T / 66. At this time, R was 3.53. When continuous operation was carried out for 8 hours, stable operation could be carried out without venting up.

Example 2
Polyamide 6T / 66 was obtained in the same manner as in Example 1 except that the operating conditions of the twin screw extruder were changed as shown in Table 1 and R was changed to 3.40. When continuous operation was carried out for 8 hours, stable operation could be carried out without venting up.

Example 3
A dissolution tank having a capacity of 350 L having a stirrer and a jacket heating function was charged with 68.4 kg of decanediamine substantially free of water and 135.7 kg of water. Subsequently, 65.9 kg of terephthalic acid substantially free of water was charged, and nitrogen substitution was performed. Furthermore, sodium hypophosphite was added as a polymerization catalyst so as to be 0.05 parts by mass with respect to 100 parts by mass of the finally obtained polyamide. Moreover, benzoic acid was added as a polymerization degree regulator so that it might become 0.0133 times mole with respect to the total mole number of dicarboxylic acid and diamine. At this time, the water content with respect to the whole charged amount was 50 mass%. And the dissolution tank was heated at 180 degreeC, and the water | moisture content in a system was evaporated and removed. Water was finally removed until the water content in the system reached 40% by mass to obtain a polyamide precursor.

  Using the polyamide precursor obtained by the above method, a prepolymer was obtained in the same manner as in Example 1 except that the residence temperature in the buffer tank was 170 ° C and the prepolymerization tank temperature was 300 ° C. Polyamide 10T was obtained in the same manner as in Example 1 except that the operating conditions of the extruder were changed as shown in Table 1 and R was changed to 3.48. When continuous operation was carried out for 8 hours, stable operation could be carried out without venting up.

Example 4
61.6 kg of hexamethylenediamine and 75.3 kg of water substantially free of water were charged into a 350 L capacity dissolution tank having a stirrer and jacket heating function. Subsequently, 77.5 kg of adipic acid substantially free of water was charged, and nitrogen substitution was performed. Furthermore, sodium hypophosphite was added as a polymerization catalyst so as to be 0.05 parts by mass with respect to 100 parts by mass of the finally obtained polyamide. Moreover, benzoic acid was added as a polymerization degree regulator so that it might become 0.0133 times mole with respect to the total mole number of dicarboxylic acid and diamine. At this time, the water content with respect to the total charged amount was 35% by mass. And the dissolution tank was heated at 180 degreeC, and the water | moisture content in a system was evaporated and removed. Water was finally removed until the water content in the system reached 20% by mass to obtain a polyamide precursor.

  Using the polyamide precursor obtained by the above method, the same procedure as in Example 1 was conducted except that the prepolymerization tank temperature was 265 ° C., the prepolymerization tank residence time was 50 minutes, and the pressure was changed to 1.8 MPa-G. A prepolymer was obtained, and the operating conditions of the twin-screw extruder were changed as shown in Table 1, and polyamide 66 was obtained in the same manner as in Example 1 except that R was 3.65. When continuous operation was carried out for 8 hours, stable operation could be carried out without venting up.

Example 5
A polyamide precursor was obtained in the same manner as in Example 4. A prepolymer was obtained in the same manner as in Example 4 except that the residence time in the prepolymerization tank was changed to 100 minutes. A polyamide 66 was obtained in the same manner as in Example 4 except that R was changed to 3.17 using the obtained prepolymer. When continuous operation was carried out for 8 hours, stable operation could be carried out without venting up.

Example 6
A polyamide precursor and a prepolymer were obtained in the same manner as in Example 4. Using the obtained prepolymer, the operating conditions of the twin screw extruder were changed as shown in Table 1, and a polyamide was obtained in the same manner as in Example 4 except that R was 4.05. When the operation was carried out continuously for 8 hours, the polymer temporarily adhered to the forevent part, but the stable operation could be carried out without venting up.

Comparative Example 1
Except that the prepolymerization tank residence time was changed to 50 minutes, a prepolymer was obtained in the same manner as in Example 1, and the operating conditions of the twin screw extruder were changed as shown in Table 1, and R was 4.65. Except for the above, an attempt was made to obtain polyamide 6T / 66 in the same manner as in Example 1, but vent-up occurred 30 minutes after the start of operation, and stable operation could not be performed.

Comparative Example 2
Except that the prepolymerization tank residence time was changed to 50 minutes, a prepolymer was obtained in the same manner as in Example 1, and the operating conditions of the twin screw extruder were changed as shown in Table 1, and R was 4.93. Except for the above, an attempt was made to obtain a polyamide in the same manner as in Example 1, but a vent-up occurred 30 minutes after the start of operation, and a stable operation could not be performed.

Comparative Example 3
A prepolymer was obtained in the same manner as in Example 1 except that the polyamide precursor was continuously supplied to a 32 L vertical cylindrical prepolymerization tank by a plunger pump at a supply rate of 6.3 kg / hr. Using the obtained prepolymer, polyamide 6T / 66 was obtained in the same manner as in Example 1 except that the operating conditions of the twin screw extruder were changed as shown in Table 1 and R was changed to 1.98. . When continuous operation was carried out for 8 hours, stable operation could be carried out without venting up. However, the discharge rate was low and the production efficiency was reduced.

  Table 1 shows various conditions and evaluation results of each example and comparative example.

1a ·· Heating and dissolving device 1b · · Buffer tank 1c · · Prepolymerization tank 1d · · Extruder 1e · · Vent port (rear vent)
1f. Vent port (fore vent)
2a ... Filling rate (V1 / V0)
2b ... Condensed water distilling rate per unit area from fore vent (S)
2c ... Virtual distillation rate (R) with zero filling rate
2d ・ ・ Extruder stable operation area

Claims (8)

A method for producing a dehydration polycondensation polymer comprising a step of dehydrating polycondensation of a prepolymer with an extruder having a vent part, wherein R defined by the following formula (1) is 2.5 or more and 4.5 or less A method for producing a dehydrated polycondensation polymer.
R = S + 1.5 × V1 / V0 (1)
V0: Effective space capacity in the extruder [cm ³ ]
V1: Total capacity [cm ³ ] of prepolymer, polymer, and water vapor contained in the extruder
S: Condensed water distillation rate per unit area from fore vent part [mg / (cm ² × sec)]   The method for producing a dehydrated polycondensation polymer according to claim 1, wherein the dehydration polycondensation polymer is polyamide.   The method for producing a dehydration polycondensation polymer according to claim 1, wherein the prepolymer has a relative viscosity of 1.38 or less.   The method for producing a dehydrated polycondensation polymer according to any one of claims 1 to 3, wherein the prepolymer is supplied to an extruder in a molten state.   The method for producing a dehydrated polycondensation polymer according to any one of claims 1 to 4, wherein the pressure in the forevent portion is less than atmospheric pressure.   The method for producing a dehydration polycondensation polymer according to any one of claims 1 to 5, wherein R is 2.5 or more and 4.0 or less.   The method for producing a dehydration polycondensation polymer according to any one of claims 1 to 6, wherein R is 2.5 or more and 3.7 or less.   The dehydrated polycondensation polymer according to any one of claims 1 to 7, further comprising a step of polycondensing a polyamide precursor under pressure in a prepolymerization tank to obtain a prepolymer before the step of dehydrating polycondensation of the prepolymer. Manufacturing method.

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