JP2012149238A - Method for producing semi-aromatic polyamide raw material, and method for producing semi-aromatic polyamide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method which continuously and stably feeds a semi-aromatic polyamide raw material including an aromatic dicarboxylic acid component, and can continuously and stably produce semi-aromatic polyamide in reduced energy consumption.SOLUTION: In the method for producing the semi-aromatic polyamide raw material, at least aromatic dicarboxylic acid, aliphatic dicarboxylic acid and aliphatic diamine are subjected to heating/melting in the presence of water of ≤30 mass%. The heating/melting is performed at ≤200°C under sealing.

Description

  The present invention relates to a method for producing a semi-aromatic polyamide raw material and a method for producing a semi-aromatic polyamide using the same. More specifically, the present invention relates to a raw material production method in a pre-polymerization stage of a semi-aromatic polyamide continuous polymerization process, and a semi-aromatic polyamide production method for continuously polymerizing the raw material.

  Aliphatic polyamides typified by nylon 6, nylon 66, nylon 610, etc. make use of their superior properties, such as clothing and industrial fibers, automobiles, electrical / electronics, extruded products such as films and monofilaments, etc. Widely used in However, it is not always sufficient as an engineering plastic often used in a high temperature environment. On the other hand, semi-aromatic polyamides whose dicarboxylic acid component is mainly composed of aromatic dicarboxylic acids are superior in low water absorption, long-term heat resistance, and chemical resistance compared to aliphatic polyamides. Demand has increased gradually.

  Generally, a polyamide composed of a dicarboxylic acid and a diamine is produced through the following process. First, a dicarboxylic acid and a diamine are reacted in water to form an aqueous salt solution that is a raw material for polyamide. The aqueous salt solution is then heated to evaporate the water and concentrated to the specified concentration. The concentrated salt aqueous solution is usually heated after being transferred to a batch-type reactor, and water remaining after concentration and condensed water generated by polymerization are evaporated to obtain polyamide. In the method for producing a semi-aromatic polyamide containing an aromatic dicarboxylic acid component, decomposition and gelation are likely to occur because of its high polymerization temperature. Thus, a production method is disclosed in which an aqueous salt solution is kneaded in a molten state to form a prepolymer and then polymerized in a solid state (see, for example, Patent Document 1). In such a batch process in which melt polymerization and solid phase polymerization are combined, the facilities become complicated and inconvenience in terms of maintenance becomes a problem.

  Therefore, a production method in which a semi-aromatic polyamide is continuously polymerized using an aqueous salt solution containing terephthalic acid and / or isophthalic acid is disclosed (for example, see Patent Document 2).

Japanese Patent Laid-Open No. 61-228022 Japanese Patent Laid-Open No. 03-17156

However, in the production method disclosed in the above prior art, a semi-aromatic polyamide raw material containing a large amount of water is used, and water contained in the semi-aromatic polyamide raw material is reduced by evaporation and concentration in the step before polymerization. . Evaporative concentration is not preferred from the viewpoint of energy efficiency. The reduction in energy consumption is urgently required from the viewpoint of CO ₂ reduction in recent years. Furthermore, in the method for producing a semi-aromatic polyamide, it becomes a factor for reducing the supply stability, which is most important in a continuous process. Evaporation concentration is usually performed in a temperature range lower than the polymerization temperature of the semi-aromatic polyamide. However, semi-aromatic polyamide has a larger equilibrium constant than other polymerized polymers, and a part of the polymerization reaction proceeds simultaneously with the evaporation of water. As a result, there has been a problem that the oligomer tends to precipitate during continuous supply of the semi-aromatic polyamide raw material by evaporation concentration.

  The present invention solves the above-mentioned problems of the prior art, continuously supplies a semi-aromatic polyamide raw material containing an aromatic dicarboxylic acid component, and continuously produces a semi-aromatic polyamide stably with a small amount of energy consumption. It is to provide a way that can be done.

  The present invention relates to a method for producing a semi-aromatic polyamide raw material in which at least an aromatic dicarboxylic acid, an aliphatic dicarboxylic acid and an aliphatic diamine are heated and dissolved in the presence of 30% by mass or less of water, and the heating and dissolution are sealed. A method for producing a semi-aromatic polyamide raw material, which is performed at a temperature of 200 ° C. or lower. Moreover, it is a manufacturing method of the semi-aromatic polyamide characterized by continuously polymerizing the semi-aromatic polyamide raw material obtained by this method.

  According to the method of the present invention, a semi-aromatic polyamide raw material can be continuously and stably supplied, and a semi-aromatic polyamide can be continuously and stably produced with a small amount of energy used. For this reason, a significant reduction in energy consumption can be realized as compared with conventional semi-aromatic polyamide raw materials and semi-aromatic polyamide production methods.

  Below, the detail of the manufacturing method of the semi-aromatic polyamide raw material of this invention and the manufacturing method of semi-aromatic polyamide is demonstrated. The semi-aromatic polyamide raw material contains at least an aromatic dicarboxylic acid or a salt of an aliphatic dicarboxylic acid and an aliphatic diamine and water. If necessary, an additive such as a polymerization degree adjusting agent and a polymerization catalyst described later may be further contained, or a polymer having a low polymerization degree between the dicarboxylic acid and the diamine may be contained. In addition, the mixture containing dicarboxylic acid, diamine, water and, if necessary, additives before being subjected to heat dissolution is hereinafter referred to as “raw material”.

  In the present invention, the aromatic dicarboxylic acid, the aliphatic dicarboxylic acid, and the aliphatic diamine may be any one that forms an aromatic amide unit or an aliphatic amide unit constituting the semi-aromatic polyamide. Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid. Two or more of these may be used. Terephthalic acid and isophthalic acid are preferred, and terephthalic acid is more preferred. As the aliphatic dicarboxylic acid, those having 2 to 18 carbon atoms are preferable. For example, adipic acid, sebacic acid, malonic acid, succinic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, undecanedioic acid, dodecanedioic acid , Tetradecanedioic acid, pentadecanedioic acid, octadecanedioic acid and the like. Two or more of these may be used. Adipic acid and sebacic acid are preferred, and adipic acid is more preferred. The aliphatic diamine is preferably one having 4 to 14 carbon atoms, such as hexamethylene diamine (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. Is mentioned. Two or more of these may be used. Hexamethylenediamine and pentamethylenediamine are preferred, and hexamethylenediamine is more preferred. Preferred combinations include terephthalic acid, adipic acid and hexamethylene diamine, isophthalic acid, adipic acid and hexamethylene diamine.

  In the method for producing a semi-aromatic polyamide raw material of the present invention, it is important that the raw material is heated and melted at a temperature of 200 ° C. or lower in a sealed state. Here, under sealing means that gas such as water vapor does not enter or leave the system. For example, in the case of a continuous production method, distillation or inflow of gas such as water vapor outside the system should be prevented. What is necessary is just to supply the raw material into the system and take out the obtained semi-aromatic polyamide raw material out of the system. By carrying out heat dissolution under sealing, it is possible to suppress the distillation of water out of the system and suppress the polymerization reaction during heat dissolution, thereby obtaining the supply stability of the semi-aromatic polyamide raw material. it can. Moreover, when heating temperature exceeds 200 degreeC, the average degree of polymerization of the semi-aromatic polyamide raw material obtained will become high, and the supply stability of a semi-aromatic polyamide raw material may be reduced. The heating temperature is preferably 190 ° C. or lower. For example, when the heating temperature at the time of heating and melting under a sealed condition is 180 ° C., the average degree of polymerization of the obtained semiaromatic polyamide raw material is usually less than 1. Here, the average degree of polymerization means an average value of the number of bonds between an aromatic dicarboxylic acid or aliphatic dicarboxylic acid and an aliphatic diamine in one molecule. When the average degree of polymerization is less than 1, the semi-aromatic polyamide raw material can be continuously supplied stably for a long time.

  In the method for producing a semi-aromatic polyamide raw material of the present invention, it is important that the amount of water in the raw material is 30% by mass or less. Here, the amount of water in the raw material refers to mass% of water in the whole raw material including aromatic dicarboxylic acid, aliphatic dicarboxylic acid, water and, if necessary, additives. When the amount of water in the raw material exceeds 30% by mass, when the semi-aromatic polyamide is produced using the semi-aromatic polyamide raw material, energy efficiency is lowered and the progress of polymerization is inhibited. From the viewpoint of energy efficiency, the amount of water is preferably as small as possible. On the other hand, the amount of water is preferably 10% by mass or more, more preferably 15% by mass or more, and more preferably 20% by mass or more from the viewpoint of further heating and dissolving the raw material at a lower temperature and further suppressing undesirable polymerization reaction. .

  Moreover, it is preferable that the pressure at the time of melt | dissolving a raw material by heating shall be more than a normal pressure in order to prevent suppression of a raw material. The pressure at the time of dissolution by heating refers to the pressure in the dissolution tank at that time, and is generally determined by the water vapor pressure at the time of dissolution equilibrium indicated by the semi-aromatic polyamide raw material containing water. Therefore, this pressure can be appropriately adjusted depending on, for example, the amount of water contained in the raw material and the heating temperature. Moreover, you may further pressurize by inert gas, such as nitrogen, as needed.

  In the method for producing a semi-aromatic polyamide raw material of the present invention, the apparatus for heating and dissolving the raw material is not particularly limited as long as it can be heated in a sealed state, and is batch-type or continuous equipped with a conventionally known heating apparatus. A reaction kettle of the formula can be used. It is preferable to have a stirrer so that the raw materials can be stirred during heating and melting.

  In the method for producing a semi-aromatic polyamide raw material of the present invention, when the raw material is heated and dissolved, oxygen may be removed from the raw material tank or the heating device before the start of heating for the purpose of preventing coloring and deterioration due to oxygen. preferable. 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 semi-aromatic polyamide in which the semi-aromatic polyamide raw material obtained by the above method is continuously polymerized will be described. A method in which a semi-aromatic polyamide raw material is continuously polymerized to obtain a semi-aromatic polyamide prepolymer (hereinafter referred to as “prepolymer”), and the prepolymer is further continuously polymerized to obtain a semi-aromatic polyamide is preferable. In order to obtain the prepolymer continuously, it is preferable to continuously supply the semi-aromatic polyamide raw material to the polymerization apparatus. When the raw material is heated and dissolved using a batch heating apparatus, a buffer tank may be provided. preferable. An example of a method for producing such a semi-aromatic polyamide will be described below.

  The semi-aromatic polyamide raw material obtained by heating and dissolving is sent to a buffer tank located on the downstream side of the heating and dissolving apparatus. The method for sending the semi-aromatic polyamide raw material from the heat-dissolving device to the buffer tank is not particularly limited, and it is sent by its own weight by keeping the pressure of the heat-dissolving device and the buffer tank at a constant pressure by using a conventionally known pump. The method etc. are mentioned. The semi-aromatic polyamide raw material sent to the buffer tank will stay until it is supplied to the polymerization apparatus located further downstream of the buffer tank. Therefore, the temperature of the buffer tank is preferably set to 200 ° C. or lower. When the temperature of the buffer tank is 200 ° C. or lower, the progress of the polymerization reaction during residence can be suppressed, and the supply stability of the semi-aromatic polyamide raw material can be maintained high. On the other hand, in order to suppress precipitation of the semi-aromatic polyamide raw material, the temperature of the buffer tank is preferably 140 ° C. or higher, and more preferably 150 ° C. or higher.

  The pressure in the buffer tank is the pressure in the buffer tank when the semi-aromatic polyamide raw material is retained, and is mainly determined by the amount of water in the semi-aromatic polyamide raw material and the temperature of the buffer tank. Therefore, this pressure can be appropriately adjusted depending on, for example, the amount of water in the semi-aromatic polyamide raw material and the temperature of the buffer tank.

  The semi-aromatic polyamide raw material staying in the buffer tank is continuously supplied to a polymerization apparatus located downstream of the buffer tank using a pump capable of supplying a fixed amount, and is continuously polymerized in the polymerization apparatus to form a prepolymer and It is preferable to do. The prepolymer referred to here is obtained by a polymerization reaction of a semi-aromatic polyamide raw material, and refers to a mixture containing an oligomer, an unreacted monomer, water and condensed water generated 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 1.3 or more, and more preferably 1.4 or more. On the other hand, the relative viscosity of the prepolymer is preferably 1.9 or less, and more preferably 1.8 or less, in order to suppress the formation of a gelled product in the polymerization apparatus due to abnormal residence. Here, the relative viscosity (ηr) of the prepolymer is a value obtained by dissolving a sample in 98% sulfuric acid at a concentration of 0.01 g / ml according to JIS K6810 and using an Ostwald viscometer at 25 ° C.

  The reaction temperature when producing the prepolymer is usually 260 to 320 ° C. In order to shorten the reaction time, the reaction temperature is preferably 270 ° C. or higher, more preferably 280 ° C. or higher. On the other hand, the reaction temperature is preferably 310 ° C. or lower, and more preferably 300 ° C. or lower, in order to suppress thermal decomposition and the formation of a gelled product.

  The pressure at the time of producing the prepolymer is usually operated so as to be maintained at 0 to 4 MPa-G, preferably 0.5 to 3.5 MPa-G. A lower pressure is preferable from the viewpoint of supply accuracy of semi-aromatic polyamide raw material and equipment cost.

  The reaction time when producing the prepolymer is usually 10 to 90 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 60 minutes or less in order to suppress thermal decomposition, formation of gelled products, and abnormal residence.

  In the present invention, the polymerization apparatus for producing the prepolymer is not particularly limited, but a polymerization apparatus in which the inside is partitioned by a perforated plate or the like is preferably used so that unnecessary convection does not occur. In the polymerization apparatus for producing the prepolymer, a rectification tower or the like can be installed on the upper part of the polymerization apparatus so that the diamine flows out together with water during pressure adjustment and the composition ratio does not shift, thereby preventing the diamine from flowing out.

  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 it can be added to the heating and dissolving apparatus during the production of the semi-aromatic polyamide raw material. 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 and hexamethylene diamine is more preferable. The addition amount of the polymerization degree modifier is preferably from 0 to 0.1 times mol, more preferably from 0.0001 to 0.05 times mol, based on the total number of moles of the dicarboxylic acid and diamine as raw materials.

  A phosphoric acid catalyst can also be used in the production of the prepolymer. The semi-aromatic polyamide raw material may be added to the heat-dissolving device during the production, or may be additionally added to the polymerization device in the next step. The phosphoric acid catalyst has a catalytic function of polymerization reaction, and specifically, phosphoric acid, phosphate, hypophosphite, acidic phosphate ester, phosphate ester, phosphite ester, etc. Two or more of these may be used. Examples of hypophosphites include sodium hypophosphite, magnesium hypophosphite, potassium hypophosphite, calcium hypophosphite, vanadium hypophosphite, manganese hypophosphite, nickel hypophosphite, Examples include cobalt phosphite. Examples of acidic phosphate esters include monomethyl phosphate ester, dimethyl phosphate ester, monoethyl phosphate ester, diethyl phosphate ester, propyl phosphate ester, isopropyl phosphate ester, dipropyl phosphate ester, diisopropyl phosphate ester, butyl phosphate ester, Examples include isobutyl phosphate ester, dibutyl phosphate ester, diisobutyl phosphate ester, monophenyl phosphate ester, and diphenyl phosphate ester. Examples of phosphate esters include trimethyl phosphate, triethyl phosphate, tri-n-propyl phosphate, tri-i-propyl phosphate, tri-n-butyl phosphate, tri-i-butyl phosphate, triphenyl phosphate, Examples include tri-n-hexyl phosphoric acid, tri-n-octyl phosphoric acid, tri (2-ethylhexyl) phosphoric acid, and tridecyl phosphoric acid. Of these, hypophosphite is preferred, and sodium hypophosphite is particularly preferred. When adding a phosphoric acid catalyst, 0.001-5 weight part is preferable with respect to 100 weight part of prepolymers, and, as for the addition amount, 0.01-1 weight part is more preferable.

  In the invention, in order to continuously and quantitatively discharge the prepolymer from the polymerization apparatus for producing the prepolymer, it is preferable to continuously supply the polymerization apparatus directly connected using a discharge device such as a gear pump and a ball valve. . A twin-screw extruder is preferable as a polymerization apparatus for continuously polymerizing the prepolymer.

  In the present invention, the prepolymer continuously fed to a polymerization apparatus such as a twin-screw extruder is usually melted in the range of the melting point of the semiaromatic polyamide finally obtained +5 to + 40 ° C., preferably the melting point +10 to + 40 ° C. The semi-aromatic polyamide is obtained by kneading and polymerization reaction. In order to increase the polymerization reaction rate, the temperature is preferably a melting point + 5 ° C. or higher. Moreover, in order to prevent thermal decomposition and the production | generation of a gelled material, temperature is preferable melting | fusing point +40 degrees C or less. Here, the melting point of the semi-aromatic polyamide refers to a temperature indicating the maximum value of the melting curve obtained by measuring at a heating rate of 20 ° C./min by the DSC method.

  Since the prepolymer containing water is continuously supplied to the twin screw extruder, it is preferable to continuously remove the water from the rear vent or the first vent installed in the vicinity of the supply port of the twin screw extruder. A semi-aromatic polyamide having a high degree of polymerization can be easily obtained by the polymerization reaction. In addition to the above, at least one vent port is installed, and the polymerization reaction is advanced by discharging water generated by the polymerization reaction of the prepolymer and a very small amount of unreacted monomer out of the system. A semi-aromatic polyamide having a polymerization degree can be easily produced. The venting is preferably carried out under reduced pressure using a known decompression / vacuum device such as a Nash pump, but the pressure is not particularly limited and can be carried out under normal pressure.

  In the present invention, the residence time in the twin-screw extruder is not particularly defined, but in order to advance the polymerization to a sufficient viscosity as a semi-aromatic polyamide and to suppress thermal degradation and thermal decomposition due to residence for a long time, 1 to 10 minutes is required. Preferably, 1 to 5 minutes is more preferable.

  In any process such as prepolymer manufacturing process, semi-aromatic polyamide manufacturing process or compounding process, catalyst, heat stabilizer, weathering stabilizer, antioxidant, plasticizer, mold release agent, lubricant, crystal as required Nucleating agents, pigments, dyes, other polymers, etc. can also be added. When compounding an additive, it is more preferable to carry out simultaneously or continuously with polymerization in a twin-screw extruder from the viewpoint of productivity. Addition of an antioxidant is effective for improving the color tone of the semi-aromatic polyamide, and the addition of sodium hypophosphite and a hindered phenol antioxidant is particularly preferable.

  The semi-aromatic polyamide obtained by the production method of the present invention can be formed into a molded product by an ordinary molding method, similarly to the conventional polyamide. 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) Uniform solubility of raw materials: A monomer and water corresponding to 1/1000 of the raw material charge amounts shown in Tables 1 and 2 were charged into a glass autoclave (in grams) and heated under sealed conditions. When the raw material dissolution temperatures listed in Tables 1 and 2 were reached, the dissolution state inside the autoclave was visually observed. A state in which no solid matter was observed was defined as a uniform solution, and a state in which the solution was cloudy or a crystal was partially deposited was defined as a heterogeneous solution.

  (2) Relative viscosity (ηr): According to JIS K6810, 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.

  (3) Melting point (Tm): Using DSC (manufactured by PERKIN-ELMER), 8 to 10 mg of sample was measured at a heating rate of 20 ° C./min, and the temperature showing the maximum value of the obtained melting curve was taken as the melting point. .

(4) Average degree of polymerization: A semi-aromatic polyamide raw material obtained by heating and dissolving was cooled and solidified in a sealed state, and further dried to measure the amino terminal group concentration of the sample obtained by the method described below. Theory of semi-aromatic polyamide raw material in which the polymerization reaction has not progressed at all The theory of semi-aromatic polyamide raw material in which the amino terminal group concentration is 732 (10 ⁻⁵ mol / g) and the polymerization reaction proceeds and the average degree of polymerization is 1. When the amino terminal group concentration was 366 (10 ⁻⁵ mol / g), the average degree of polymerization was determined from the measured amino terminal group concentration of the sample as shown in A and B below.
A. 0 <amino end group concentration ≦ 366: average degree of polymerization of 1 or more 366 <amino end group concentration ≦ 732: average degree of polymerization less than 1

(5) Amino end group concentration: 0.1 g of dried sample was precisely weighed, 50 mL of PEA solution (phenol 83.5: ethanol 16.5, volume ratio) was added and dissolved by shaking, and 0.02N hydrochloric acid was added. And titrated.
Amino end group (10 ⁻⁵ mol / g) = (A−B) × f × 0.02 × 10 ⁻³ / dry sample weight
A: 0.02N hydrochloric acid amount (mL) required for titration
B: 0.02N hydrochloric acid amount (mL) required for the blank test
f: 0.02N hydrochloric acid titer

Example 1
A dissolving tank having a capacity of 350 L having a stirrer and a jacket heating function was charged with 69.0 kg of hexamethylenediamine substantially free of water and 40.6 kg of water. Subsequently, 40.7 kg of adipic acid substantially free of water and 52.5 kg of terephthalic acid substantially free of water were charged, and nitrogen substitution was performed. Further, sodium hypophosphite was added as a polymerization catalyst so as to be 0.05 parts by weight with respect to 100 parts by weight of the finally obtained semi-aromatic 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 20% by mass. The dissolution tank was closed and heated until the internal temperature reached 180 ° C. to obtain a semi-aromatic polyamide raw material. At this time, the pressure in the dissolution tank increased to 0.50 MPa-G. Subsequently, the semi-aromatic polyamide raw material was sent by its own weight to the dissolution tank and the pressure-retained buffer tank through a pressure equalizing pipe, and the residence temperature in the buffer tank was maintained at 160 ° C. The semi-aromatic polyamide raw material obtained by the above method is continuously supplied to a 4 L vertical cylindrical polymerization apparatus at a supply rate of 6.30 kg / hr using a plunger pump, and pre-treated under the conditions described in Table 1. The polymer was continuously polymerized. Subsequently, the degree of polymerization was increased with a twin-screw extruder under the conditions described in Table 1, to obtain a semi-aromatic polyamide. There was no problem in the continuous supply of the semi-aromatic polyamide raw material, and a stable continuous supply was achieved. The obtained semi-aromatic polyamide had a viscosity (ηr) of 2.45 and a melting point of 301.0 ° C., and could be produced without problems for 24 hours or more.

Example 2
A semi-aromatic polyamide raw material was obtained in the same manner as in Example 1 except that the amount of water charged was changed to 69.5 kg. The water content relative to the total amount charged was 30% by mass, and the pressure in the dissolution tank was increased to 0.58 MPa-G. Using the obtained semi-aromatic polyamide raw material, a prepolymer was obtained in the same manner as in Example 1 to obtain a semi-aromatic polyamide. There was no problem in the continuous supply of the semi-aromatic polyamide raw material, and a stable continuous supply was achieved. The obtained semi-aromatic polyamide had a viscosity (ηr) of 2.24 and a melting point of 300.2 ° C., and could be produced without problems for 24 hours or more.

Example 3
A semi-aromatic polyamide raw material was obtained in the same manner as in Example 2 except that heating was performed until the internal temperature reached 165 ° C. when the raw material was dissolved. The water content with respect to the total charge was 30% by mass, and the pressure in the dissolution tank was increased to 0.40 MPa-G. Using the obtained semi-aromatic polyamide raw material, a prepolymer was obtained in the same manner as in Example 2 except that the residence temperature in the buffer tank was maintained at 145 ° C. to obtain a semi-aromatic polyamide. There was no problem in the continuous supply of the semi-aromatic polyamide raw material, and a stable continuous supply was achieved. The obtained semi-aromatic polyamide had a viscosity (ηr) of 2.21 and a melting point of 299.0 ° C., and could be produced without problems for 24 hours or more.

Example 4
A semi-aromatic polyamide raw material was obtained in the same manner as in Example 1 except that the amount of water charged was changed to 28.6 kg and heated until the internal temperature reached 185 ° C. when the raw material was dissolved. The water content relative to the total charge was 15% by mass, and the pressure in the dissolution tank was increased to 0.55 MPa-G. Using the obtained semi-aromatic polyamide raw material, a prepolymer was obtained in the same manner as in Example 1 except that the residence temperature in the buffer tank was maintained at 170 ° C. to obtain a semi-aromatic polyamide. There was no problem in the continuous supply of the semi-aromatic polyamide raw material, and a stable continuous supply was achieved. The obtained semi-aromatic polyamide polymer had a viscosity (ηr) of 2.52 and a melting point of 300.5 ° C., and could be produced without problems for 24 hours or more.

Example 5
In the same manner as in Example 1, a semi-aromatic polyamide raw material was obtained. The water content relative to the total charge was 20% by mass, and the pressure in the dissolution tank was increased to 0.50 MPa-G. Using the obtained semi-aromatic polyamide raw material, a prepolymer was obtained in the same manner as in Example 1 except that the residence temperature in the buffer tank was maintained at 220 ° C. to obtain a semi-aromatic polyamide. There was no problem in the first stage of continuous supply of the semi-aromatic polyamide raw material, but there was a problem that the supply became impossible 12 hours after the start of continuous supply. Meanwhile, the viscosity (ηr) of the obtained semi-aromatic polyamide polymer was 2.47, and the melting point was 300.0 ° C.

Example 6
70.4 kg of hexamethylenediamine and 45.0 kg of water substantially free of water were charged into a 350 L capacity dissolution tank having a stirrer and jacket heating function. Subsequently, 49.2 kg of sebacic acid substantially free of water and 60.4 kg of terephthalic acid substantially free of water were charged, and nitrogen substitution was performed. In addition, sodium hypophosphite was added as a polymerization catalyst so that it might be 0.05 weight part with respect to 100 weight part of semi-aromatic polyamide obtained after superposition | polymerization. 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. The water content relative to the total charge was 20% by mass. The dissolution tank was closed and heated until the internal temperature reached 180 ° C. to obtain a semi-aromatic polyamide raw material. At this time, the pressure in the dissolution tank increased to 0.50 MPa-G. Using the obtained semi-aromatic polyamide raw material, a prepolymer was obtained in the same manner as in Example 1 to obtain a semi-aromatic polyamide. There was no problem in the continuous supply of the semi-aromatic polyamide raw material, and a stable continuous supply was achieved. The obtained semi-aromatic polyamide had a viscosity (ηr) of 2.42 and a melting point of 303.0 ° C., and could be produced without problems for 24 hours or more.

Comparative Example 1
A semi-aromatic polyamide raw material was obtained in the same manner as in Example 1 except that the amount of water charged was changed to 108.1 kg and heated until the internal temperature reached 160 ° C. when the raw material was dissolved. The water content with respect to the total charge was 40% by mass, and the pressure in the dissolution tank was increased to 0.35 MPa-G. Using the obtained semi-aromatic polyamide raw material, the prepolymer was continuously polymerized in the same manner as in Example 1, followed by increasing the degree of polymerization with a twin-screw extruder. There was no problem in the continuous supply of the semi-aromatic polyamide raw material, and a stable continuous supply was possible. However, a vent-up occurred when the degree of polymerization in the twin screw extruder was increased, and a stable continuous operation was not possible.

Comparative Example 2
A semi-aromatic polyamide raw material was obtained in the same manner as in Example 1 except that the amount of water charged was changed to 18.0 kg and heated until the internal temperature reached 220 ° C. when the raw material was dissolved. The water content with respect to the total charge was 10% by mass, and the pressure in the dissolution tank was increased to 0.80 MPa-G. Moreover, the average degree of polymerization at this time was 1 or more. Using the obtained semi-aromatic polyamide raw material, an attempt was made to supply to the polymerization apparatus in the same manner as in Example 1 except that the residence temperature in the buffer tank was changed to 180 ° C. The semi-aromatic polyamide raw material was precipitated and solidified, and the continuous operation was stopped.

Comparative Example 3
A dissolving tank having a capacity of 350 L having a stirrer and a jacket heating function was charged with 69.0 kg of hexamethylenediamine substantially free of water and 162.2 kg of water. Subsequently, 40.7 kg of adipic acid substantially free of water and 52.5 kg of terephthalic acid substantially free of water were charged, and nitrogen substitution was performed. In addition, sodium hypophosphite was added as a polymerization catalyst so that it might be 0.05 weight part with respect to 100 weight part of semi-aromatic polyamide obtained after superposition | polymerization. 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. The water content relative to the total charge was 50% by mass. The dissolution tank was heated to evaporate and remove water in the system while maintaining the pressure at 0.30 MPa-G. Water was finally removed until the water content in the system reached 15% by mass to obtain a semi-aromatic polyamide raw material. The average degree of polymerization at this time was 1 or more. Using the obtained semi-aromatic polyamide raw material, an attempt was made to supply to the polymerization apparatus in the same manner as in Example 1 except that the residence temperature in the buffer tank was changed to 180 ° C. The semi-aromatic polyamide raw material was precipitated and solidified, and the operation was stopped.

  The raw material preparation amount of each Example and a comparative example, manufacturing conditions, and an evaluation result are shown to Tables 1-2.

Claims (4)

A method for producing a semi-aromatic polyamide raw material in which at least an aromatic dicarboxylic acid, an aliphatic dicarboxylic acid and an aliphatic diamine are heated and dissolved in the presence of 30% by mass or less of water. A method for producing a semi-aromatic polyamide raw material, which is performed at a temperature. The aromatic dicarboxylic acid is terephthalic acid and / or isophthalic acid, the aliphatic dicarboxylic acid is adipic acid and / or sebacic acid, and the aliphatic diamine is hexamethylenediamine and / or pentamethylenediamine. The method for producing a semi-aromatic polyamide raw material according to claim 1, characterized in that: A method for producing a semi-aromatic polyamide, comprising continuously polymerizing a semi-aromatic polyamide raw material obtained by the production method according to claim 1 or 2. The semi-aromatic polyamide raw material obtained by the production method according to claim 1 or 2 is continuously fed to a polymerization apparatus from a buffer tank heated at a temperature of 200 ° C or lower. Manufacturing method.