JPH07188409A - Preparation of polyamide resin - Google Patents

Abstract

PURPOSE:To efficiently prepare a particular polyamide resin having high rigidity and high heat distortion temp. by preparing a polyamide resin having a hexamethyleneterephthalamide structure in such a manner that, after a terephthalic acid component is fed in portions to conduct a primary condensation, the degree of polymerization is further increased. CONSTITUTION:This polyamide resin has a copolymer structure comprising repeating units of the formula. It is prepared by conducting the step of synthesizing a primary condensate at 150 to 350 deg.C to give a primary condensate having a relative viscosity of 1.04 to 2.5 as measured at 25 deg.C in the 1% sulfuric acid soln. thereof and further increasing the degree of polymn. of the condensate. In the step of synthesizing the primary condensate, starting materials for providing the repeating units of the formula are fed both when the reaction temperature is below 150 deg.C and when the reaction temperature is 150 deg.C or above. The starting materials for providing the repeating units of the formula are preferably terephthalic acid and hexamethylenediamine or a salt of both the above compds. The m.p. of the polyamide resin is pref. 230 to 340 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyamide resin by synthesizing a primary condensate from an aqueous solution of a monomer or a salt as a constituent unit and then increasing the degree of polymerization, and is particularly suitable for automobile parts and electric / electronic parts. And a method for producing a polyamide resin.

[0002]

2. Description of the Related Art Polyamides have been widely used in the fields of automobiles, electric and electronic fields, etc. by utilizing their excellent properties as engineering plastics.

Conventionally, nylon 6 and nylon 66 reinforced with glass fibers have been used for these molded articles (Japanese Patent Laid-Open No. 59-161461), but the temperature rise in the engine room of automobiles due to recent technological innovations and With the progress of microelectronics, there has been a demand for materials for molded products that can withstand use in a higher temperature atmosphere. However, the melting points (Tm) of nylon 6 and nylon 66 are 220 ° C. and 260 ° C., respectively, and even when reinforced with glass fiber, the limits of the heat distortion temperature are only the melting points.

Recently, many polyamide resin compositions having terephthalic acid and isophthalic acid components or glass-reinforced products thereof have been proposed as polyamide resin compositions capable of withstanding use under these high temperature atmospheres (JP-A-59).
No. 161428, No. 59-155426, No. 59-53536, and No. 62-15.
6130). In addition, as a method for producing these, there has been proposed a method of performing a polymerization reaction in a solid state from a nylon salt to a polymer (JP-A-62-20527).
Issue). However, the polyamide resin having these terephthalic acid and isophthalic acid components has a high melt viscosity as the number of terephthalic acid component units increases, which makes it impossible to discharge by a normal melt polymerization method, and the polymer melting point is higher than the thermal decomposition temperature of the polymer. Since they are close to each other, they were decomposed or deteriorated during melt polymerization. Further, the method of carrying out the polymerization reaction in a solid state from the nylon salt to the polymer has a problem that the composition of the polymer is not stable.

As a means for solving these problems, the inventors, as disclosed in Japanese Patent Application Laid-Open No. 4-502231,
After synthesizing the primary condensate at a temperature of 150 ° C. or higher,
We proposed a method for efficiently obtaining a polyamide resin composition containing a terephthalic acid component by further increasing the degree of polymerization. Conventionally, in this method, the raw material is generally introduced into the primary condensate synthesizing step before the step of synthesizing the primary condensate is started, that is, after being charged into the container at a temperature of less than 150 ° C.

[0006]

However, even in the method of going through the primary condensate synthesis step, if all the raw materials are charged before the primary condensate synthesis step, the terephthalic acid in the desired polyamide resin can be obtained. As the number of component units increases, problems often occur in the synthesis process of the primary condensate, such that the primary condensate precipitates and the melt viscosity increases, resulting in ejection failure, and a polyamide resin with higher heat resistance. Had to be solved in order to obtain.

[0007]

In view of the above circumstances, the present inventors have stably produced an inexpensive polyamide resin composition having a high rigidity and a high heat distortion temperature that can sufficiently withstand use in a high temperature atmosphere. As a result of diligently studying the method, a part of the raw material that gives the terephthalic acid component was divided and supplied during the primary condensate synthesis process to synthesize the primary condensate, and then by increasing the degree of polymerization, it became stable efficiently. The present invention has been accomplished by finding that a polymer having a high degree of polymerization can be obtained. That is, the present invention has the following structural formula (I)

[Chemical 5] A polyamide resin having a copolymer structure containing a repeating unit represented by the formula (1) is prepared by a primary condensate synthesis step at 150 to 350 ° C. to obtain a primary condensate having a relative viscosity at 25 ° C. of a 1% sulfuric acid solution of 1.04 to 2.5. In the primary condensate synthesizing step, the reaction is performed at a reaction temperature of lower than 150 ° C. and a reaction temperature of 15
A method for producing a polyamide resin, characterized in that a raw material which gives the structural formula (I) is supplied at each of the synthetic steps at 0 ° C. or higher.

The details of the present invention will be described below.

The (I) hexamethylene terephthalamide unit (hereinafter abbreviated as 6T), which is a feature of the present invention, has a function of imparting rigidity and heat resistance to the obtained polyamide resin. Further, in terms of heat resistance of the obtained resin, the melting point of the obtained polyamide resin is preferably 230 ° C to 340 ° C, and further 27
It is preferably 0 to 340 ° C. This is because when the melting point is low, the heat resistance of the obtained resin becomes low, and when the melting point is too high, the polyamide tends to be thermally decomposed and deteriorated during melting.

The polyamide resin obtained here is 6T.
In addition to the components, a polyamide having one or more kinds of repeating units selected from the following structures (II) to (IV) is preferable.

[0011]

[Chemical 6] A hexamethylene isophthalamide unit represented by (hereinafter referred to as 6I).

[0012]

[Chemical 7] Hexamethylene adipamide unit (hereinafter 66
Indicate).

[0013]

[Chemical 8] A caproamide unit represented by (6).

In these copolymerized polyamides, for example, in the case of 2 components, the copolymerization ratio of 6T / 6I is 45 / 55-80 / 20 by weight, preferably 55 / 45-.
It is used in the range of 80/20, more preferably 60/40 to 75/25. Further, in 6T / 66, the copolymerization ratio is 20/80 to 80/20 in weight ratio, preferably 30/7.
0-70 / 30, more preferably 30 / 70-60 / 4
Used in the range of 0. Further, in 6T / 6, the copolymerization ratio is 40/60 to 90/10 by weight, preferably 5
5/45 to 85/15, more preferably 60/40 to 8
Used in the range of 0/20. 6T / 6I here,
The 6T / 66 and 6T / 6 polyamide copolymerization ratios are for crystalline polyamides having a polymer melting point in the range of approximately 230 ° C to 340 ° C. 6T / 6I, 6
When the copolymerization ratio by weight of T / 66 and 6T / 6 is less than 45/55, 20/80 and 40/60, respectively, the polymer melting point is lowered, heat resistance such as heat distortion temperature is lowered, and 6T is contained. It is not preferable in terms of increase in water absorption due to decrease in amount. Also, 6T / 6I, 6T / 66 and 6T
/ 6 copolymerization ratio of 80/20, 80/20,
When it is more than 90/10, the polymer melting point becomes high and the heat resistance is improved, but the processing temperature becomes high and the polymer causes thermal decomposition, which is not preferable.

The structural unit may be composed of three or more components, and may contain a known polyamide unit in addition to the above (I) to (IV). Examples thereof include a tetramethylene adipamide unit, a hexamethylene sebacamide unit, a hexamethylene dodecamide unit, a lauroamide unit, a paraxylylene adipamide unit, and a metaxylylene adipamide unit.

The degree of polymerization of the polyamide resin obtained in the present invention is not particularly limited, and is usually 25 ° C. of a 1% sulfuric acid solution.
Relative viscosity (hereinafter referred to as ηr) is 1.8 to
Any of those in 5.0 can be used.

In the present invention, the starting material for the primary condensate to be first synthesized is generally a monomer such as a cyclic amide, an aminocarboxylic acid, a dicarboxylic acid or a diamine,
Further, a salt composed of dicarboxylic acid and diamine is used. Further, these raw materials can be supplied as a solution such as water. In particular, as a raw material (hereinafter referred to as a terephthalic acid component) that gives the structural formula (I) to the polyamide resin, which is a feature of the present invention, terephthalic acid and hexamethylenediamine, or salts of both are preferably used. .

The polymerization reaction for synthesizing the primary condensate is
Charge one or more of the raw materials exemplified above into a pressure-type polymerization tank,
It is obtained by heating to 150 to 350 ° C. under stirring conditions. In order to increase the efficiency of the polymerization tank, it is preferable to charge the raw material mixed aqueous solution as a raw material at a concentration of 50% or more, preferably 65% or more.

The pressure type polymerization tank for producing the primary condensate of the present invention is not particularly limited, and may be a batch reactor or 1 to 3
Known devices such as a tank-type continuous reaction device can be used. The amount of the raw material terephthalic acid component is determined by the amount of the structural formula (I) in the target polyamide. In order to solve the problems of the present invention, the supply of the terephthalic acid component is
It is carried out between before the start of the primary condensate synthesis step until the reaction temperature is lower than 150 ° C. (hereinafter referred to as initial supply) and during the polymerization reaction at a reaction temperature of 150 ° C. or higher (hereinafter referred to as late supply).

In the supply of the terephthalic acid component, the division ratio (initial supply / late supply) is 50/1 to weight.
It is preferably 1/1, more preferably 20/1 to 1/1. In each of the initial supply and the latter supply, it is possible to supply a plurality of times or supply for a continuous time. If the ratio of the initial supply of the terephthalic acid component is too high, the polymer may precipitate in the polymerization tank during the polymerization heating, which is not preferable, and if the ratio is too low, the polymerization reaction takes time, which is not preferable.

Further, it is preferable that 50% or more of the raw material supplied in the latter-stage feed material is supplied at 190 ° C. or higher. As a method of supplying the terephthalate component at a later stage, a method of adding from a pressure pot or a metering pump is suitable.

The reaction temperature for preparing the primary condensate by the polymerization reaction of the primary condensate must be 150 to 350 ° C, preferably 180 to 340 ° C, and more preferably 190 ° C to 340 ° C. When the reaction temperature is lower than 150 ° C, the reaction time becomes long, which is not preferable. Further, if the reaction temperature is higher than 350 ° C., foaming or gel-like foreign matter is significantly generated due to thermal decomposition of the primary condensate, which is not preferable.

The pressure in the step of synthesizing the primary condensate is usually 0 to 1
It is operated to keep it at 00 kg / cm ² -G, preferably ^{2 to} 70 kg / cm ² -G, more preferably 5 to 60 kg / cm ² -G. The primary condensate can be discharged from the polymerization tank in a molten state at a temperature of 150 to 350 ° C. due to the effect of the present invention and the freezing point depression due to the presence of a small amount of water.

25% of 1% sulfuric acid solution of the obtained primary condensate
1.04 to 2.5 as relative viscosity (ηr) at ℃
It is necessary to be 1.08-2.
3, more preferably 1.08 to 2.1. When the relative viscosity is less than 1.04, the reaction time in the polymerization degree increasing step becomes long, and when the relative viscosity is more than 2.5, the melt viscosity of the primary condensate becomes too high and ejection failure occurs, which is preferable. Absent.

In addition, in the usual polyamide polymerization, it is common to charge the raw materials so that the total amount of carboxyl groups and the total amount of amino groups contained in the monomer and the salt are equal. It is also possible to prepare a primary condensate having a large number of carboxyl groups or amino groups by adding an excess of dicarboxylic acid component or diamine component during charging. A preferable charging ratio is to charge the dicarboxylic acid component or the diamine component in an excess of 0 to 10 mol% with respect to the total number of moles of the constituent monomers. If it exceeds 10 mol%, it is difficult to increase the degree of polymerization, which is not preferable.
The dicarboxylic acid component is not particularly limited, but examples thereof include an aliphatic dicarboxylic acid component such as adipic acid and sebacic acid, and an aromatic dicarboxylic acid such as terephthalic acid isophthalic acid. The diamine component is not particularly limited, but examples thereof include aliphatic diamines such as tetramethylenediamine and hexamethylenediamine. When the dicarboxylic acid component or diamine component is overcharged, a shortage of the diamine component or dicarboxylic acid component can be added in order to control the polymerization rate in the melt polymerization degree increasing step.

Further, in order to facilitate the control of the degree of polymerization of the primary condensate and the degree of polymerization in the step of increasing the degree of polymerization, it is effective to add a degree of polymerization regulator. As the polymerization degree regulator, a monoamine compound and a monocarboxylic acid compound are usually used, but acetic acid, benzoic acid, stearic acid and the like are preferable. The addition amount of the polymerization regulator is 0 to 0.1 times mol, preferably 0.0001 to 0.05 mol, based on the total number of moles of the constituent monomer and dicarboxylic acid component unit and diamine component unit of the salt. Used.

Further, the primary condensate is highly polymerized to form a polyamide resin. As a method of increasing the degree of polymerization of the primary condensate, a method using a melting machine, a method of solid phase polymerization, a method of using a melting machine, a solid phase polymerization machine in combination, and the like can be used. When using a melting machine, the melting temperature is preferably in the range of 10 to 70 ° C. higher than the melting point of the primary condensate. When a primary condensate having a high terephthalic acid component and a high melting point is used, the upper limit temperature is set to 37 to prevent thermal decomposition or thermal deterioration of the polymer.
It must be 0 ° C or lower. As the melt extruder, an extruder or a kneader can be used, but a twin screw extruder or a twin screw kneader is preferable.

The residence time in the melting machine is not particularly limited, but it is preferably 20 seconds or longer, particularly preferably 30 seconds or longer. If the residence time is short, the degree of polymerization cannot be effectively increased, which is not preferable. It is also effective to connect two or more melting machines in series in order to lengthen the residence time and promote a high degree of polymerization. The phosphorus-based catalyst is effective for increasing the degree of polymerization, and may be added if necessary. Further, the polymer having a high degree of polymerization can be subjected to solid phase polymerization as necessary to further increase the degree of polymerization.

In the case of solid-phase polymerization, the method may be a method of applying pressure or normal pressure in the presence of an inert gas, a method of reducing pressure, or a combination thereof. The solid phase polymerization temperature is required to be in the range of 130 ° C to the melting point of the primary condensate. Preferably,
170 ° C to melting point -10 ° C, more preferably 200 ° C to
Melting point is -15 ° C. If the solid phase polymerization temperature is lower than 130 ° C., the reaction rate becomes slow, which is not preferable. As the solid-phase polymerization time, an arbitrary time until the relative viscosity of the polyamide resin used for a usual molded product is reached can be selected. The polymerization apparatus of the present invention is not particularly limited, and any known method can be used. Specific examples of the solid-state polymerization apparatus include a kneader, a twin-screw paddle type, a tower type, a rotating drum type, and a double-cone type solid-state polymerization apparatus.

A filler can be added to the polyamide resin obtained in the present invention. The filler is a glass fiber or beads, talc, kaolin, wollastonite, mica, silica, alumina, kieselguhr, clay,
Gypsum, red iron oxide, graphite, titanium dioxide, powdered or plate-like inorganic compounds such as zinc oxide, copper and stainless, other polymer fibers (carbon fibers), etc., preferably glass fibers. Particularly preferred as glass fibers are glass rovings, glass chopped strands, glass yarns and the like made from strands of continuous long fibers having a diameter of about 3 to 20 μm. The blending ratio of such a filler is usually in the range of 0 to 200 parts by weight, preferably more than 0 and 150 parts by weight, particularly preferably 10 to 100 parts by weight, relative to 100 parts by weight of the polyamide. When the blending ratio of the filler exceeds 200 parts by weight, the fluidity at the time of melting deteriorates, and it becomes difficult to injection-mold a thin-walled molded product, and the appearance of the molded product deteriorates, which is not preferable.

There is no particular limitation on the method of adding the filler to the polyamide resin of the present invention, and any known method can be used. Specific examples of the compounding method include a method in which pellets of polyamide resin are dry-blended with a filler, and the resulting mixture is melt-kneaded with a single-screw or twin-screw extruder. In particular, when the degree of polymerization of the primary condensate is increased by an extruder, a method of side-feeding in the middle of the extruder is preferable because of high production efficiency.

In the present invention, a catalyst, a heat resistance stabilizer, a weather resistance stabilizer, a plasticizer, a plasticizer, a heat stabilizer, a plasticizer, etc. may be added as necessary during the primary condensate synthesis step, the melt polymerization degree, the solid phase polymerization, the compound or the molding step. Agent, mold release agent, lubricant, crystal nucleating agent,
Pigments, dyes, other polymers and the like can be added.

These additives include heat-resistant stabilizers (hindered phenol type, hydroquinone type, phosphite type and substitution products thereof, copper iodide, potassium iodide, etc.), weather resistance stabilizers (resorcinol type, salicylate). Type, benzotriazole type, benzophenone type, hindered amine type, etc., mold release agent and lubricant (montanic acid and its salt, its ester, its half ester, stearyl alcohol, stearamide and polyethylene wax etc.), pigment (cadmium sulfide, phthalocyanine type) Compounds, carbon black, etc.), and dyes (such as nigrosine), other polymers (other polyamides, polyesters, polycarbonates, polyphenylene ethers, polycarbonates, polyphenylene ethers, polyphenylene sulfides, Crystal polymers, polyether sulfone, ABS resin, SAN resin, polystyrene, acrylic resins, polyethylene, polypropylene, ethylene, alpha-
Olefin copolymer, ionomer resin, SBS, SE
BS, etc.).

From the viewpoint of productivity, it is more preferable that the compounding of these additives is carried out simultaneously or continuously with the polymerization degree increasing in the melting machine.

Addition of an antioxidant is effective for improving the color tone of the polyamide, and addition of sodium hypophosphite and a hindered phenol type antioxidant is particularly preferable. Sodium hypophosphite is also effective in promoting a high degree of polymerization of the primary condensate.

The polyamide of the present invention includes switches, ultra-small slide switches, DIP switches, switch housings, lamp sockets, binding bands, connectors, connector housings, connector shells, IC sockets,
Coil bobbins, bobbin covers, relays, relay boxes, condenser cases, motor internal parts, small motor cases, gear cams, dancing pulleys, spacers, insulators, fasteners, buckles,
Wire clips, bicycle wheels, casters, helmets, terminal blocks, power tool housings, starter insulation parts, spoilers, canisters, radiator tanks, chamber tanks, reservoir tanks, fuse boxes, air cleaner cases, air conditioner fans,
Typical examples include terminal housings, wheel covers, intake and exhaust pipes, bearing retainers, cylinder head covers, intake manifolds, water pipe impellers, clutch releases, speaker diaphragms, heat resistant containers, microwave oven parts, rice cooker parts, printer ribbon guides, etc. Electric / electronic related parts, automobile / vehicle related parts,
It is useful for home appliances / office electrical appliances parts, computer related parts, facsimile / copier related parts, machine related parts, and other various applications.

[0037]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples without departing from the spirit of the invention. The properties in the examples and comparative examples were measured by the following methods.

1) Melting point (Tm) Samples 8 to 10 using DSC (PERKIN-ELMER7 type)
The temperature showing the maximum value of the melting curve obtained by measuring mg at a temperature rising rate of 20 ° C./min was defined as Tm.

2) The physical properties of the molded product were measured by the following methods.

Tensile Strength: ASTM-D638 Bending Strength: ASTM-D790 Bending Elastic Modulus: ASTM-D790 Izod Impact Strength: ASTM-D256 Heat Deformation Temperature (HDT): ASTM-D648 Load 4.6 kgf / cm ² Load 18.6 kgf / cm ² <Example 1> Hexamethylene ammonium adipate (66
Salt) 16.5 kg, a salt of terephthalic acid and hexamethylenediamine (6T salt), which is a raw material to give hexamethylene terephthalamide units (13.5 kg), benzoic acid 135 g
Then, 12.5 kg of ion-exchanged water was charged into a 0.1 m ³ batch type polymerization tank. At this time, the temperature in the tank was 60 ° C. After sufficiently purging with nitrogen, steam pressure 18kg / cm ²
Heating continued under pressure of -G. 280 ° C over 3 hours with stirring
Then, 10 kg of a 30% by weight 6T salt aqueous solution heated to 130 ° C. was fed to the polymerization tank at a rate of 8 l / h by using a feed pump. The temperature was further raised to 300 ° C. over 1 hour to complete the reaction. During this time, the load current of the stirrer is 2.4-
It was stable at 2.6A. After the completion of the reaction, the primary condensate was discharged from the lower part of the polymerization tank into water to obtain a white lump. This lump was centrifugally dehydrated, then pulverized and dried in a vacuum dryer at 100 ° C. for 24 hours. The viscosity of the obtained primary condensate is ηr =
The melting point was 1.45 and the melting point was 295 ° C. This primary condensate is heated at 260 ° C to 335 ° C with a vent type twin-screw extruder having a diameter of 30 mm.
Melt extrusion was performed under the temperature conditions of. Polymer viscosity η r = 2.
A white pellet having a melting point of 70 and a polymer melting point of 293 ° C. was obtained.

Length 3 for 100 parts by weight of this pellet
mm Glass fiber chopped strand 50 with diameter 13 μm
Parts by weight were dry-blended, and melt-mixed at a temperature of polymer melting point + 20 ° C. with a 30 mmφ single screw extruder. This mixture was molded by an injection molding machine to prepare a test piece. Table 1 shows the results of evaluation of the obtained test pieces.

<Example 2> 85% by weight aqueous solution of ε-caprolactam as a raw material for providing caproamide units = 1
1.8 kg, 5.89 kg of terephthalic acid, 6.33 kg of a 65 wt% aqueous solution of hexamethylenediamine, 155 g of benzoic acid and 4.6 kg of ion-exchanged water were charged in a 0.1 m ³ batch pressure polymerization tank. The temperature in the bath at this time was 60 ° C. After sufficiently purging with nitrogen, steam pressure 1
Heating was continued under a pressure of 7.5 kg / cm ² -G. With stirring 2.
After the temperature was raised to 270 ° C. over 5 hours, 13.9 kg of a 60 wt% 6T salt aqueous solution heated to 160 ° C. was fed to the polymerization tank at a rate of 15 l / h by a metering pump, and further 2
The temperature was raised from 70 to 300 ° C. over 1 hour to complete the reaction. During this period, the stirrer load current was stable at 2.4 to 2.6A. Discharging, centrifugal dehydration, pulverization and drying were carried out in the same manner as in Example 1. The melting point of the obtained primary condensate is 2
96 degreeC and (eta) r were 1.43. This was melt-extruded by the method of Example 1, compounded and molded, and evaluated. The results are shown in Table 1.

<Example 3> The primary condensate obtained in Example 1 was placed in a DS3-7.5 type kneader manufactured by Moriyama Seisakusho, and the temperature was raised to 250 ° C over 2 hours while blowing nitrogen (3 l / min). did. Further, the temperature was maintained at 250 ° C. for 3 hours and then cooled to room temperature. A white powder having ηr = 2.67 and Tm = 295 ° C. was obtained. This powder was pelletized at a temperature of 200 to 320 ° C. using a PLA Giken 30 mmφ single screw extruder,
It was dried in a vacuum dryer at 100 ° C. for 16 hours. Table 1 shows the results of compounding and molding evaluation of glass pellets by the method of Example 1.

Comparative Example 1 15.0 kg of hexamethylene ammonium adipate (66 salt), 15.0 kg of a salt of terephthalic acid and hexamethylene diamine (6T salt), 135 g of benzoic acid and 12.5 kg of ion-exchanged water were added.
A batch type polymerization tank of 1 m ³ was charged. The temperature in the bath at this time was 60 ° C.

After sufficiently purging with nitrogen, steam pressure 18 kg / c
Heating was continued under pressure of m ² -G. 30 for 4 hours under stirring
After the temperature was raised to 0 ° C., the reaction was completed. During this time, the internal temperature is 2
The load current of the agitator is usually 2. over 60 to 285 ° C.
It rose sharply from 5A to 2.8A. After the reaction was completed, an attempt was made to eject as in Example 1, but almost no ejection was possible.

This polymerization condition was 6 for the divided charge of Example 1.
This is because the molten primary condensate was precipitated and solidified during the polymerization, although the total amount charged and the main polymerization conditions were the same except that the T salt was charged all at once before the start of the polymerization.

<Comparative Example 2> 6T of the divided charge of Example 2
The salt was changed to batch charging before the start of polymerization, and a 85% by weight aqueous solution of ε-caprolactam = 11.8 kg, 6T salt flakes 1
8.2 kg, 155 g of benzoic acid and deionized water 1
2.9 kg was charged into a 0.1 m ³ batch type pressure polymerization tank. The temperature in the bath at this time was 60 ° C. After sufficiently purging with nitrogen, heating was continued under a steam pressure of 17.5 kg / cm ² -G. After heating to 300 ° C. over 3.5 hours with stirring, the reaction was completed. The internal temperature during this time is 265-2
Over 90, the stirrer load current is normally 2.4-2.6A
To 2.9A. After the reaction was completed, an attempt was made to discharge in the same manner as in Example 1, but the charged amount was 10
Only about wt% could be discharged.

[0048]

[Table 1]

[0049]

EFFECTS OF THE INVENTION In the step of synthesizing the primary condensate, which is a feature of the present invention, by supplying the terephthalic acid component in a divided manner, the reaction product may be precipitated or the viscosity in the step of synthesizing the primary condensate may be increased, and ejection may be impossible. The problem can be solved, and therefore, a polyamide resin having a terephthalic acid component having good heat resistance can be efficiently and stably produced.

Claims (5)

[Claims] 1. The following structural formula (I): The polyamide resin having a copolymer structure containing a repeating unit represented by the formula (1) was subjected to a primary condensate synthesis step at 150 to 350 ° C to obtain a primary condensate having a relative viscosity of 1.04 to 2.5 at 25 ° C of a 1% sulfuric acid solution. In the primary condensate synthesizing step, wherein the reaction temperature is lower than 150 ° C. and the reaction temperature is 15 ° C.
A method for producing a polyamide resin, which comprises supplying a raw material giving the structural formula (I) at each of the synthesis step at 0 ° C. or higher. 2. The method for producing a polyamide resin according to claim 1, wherein the raw material giving the structural formula (I) is terephthalic acid and hexamethylenediamine, or a salt of both. 3. The polyamide resin has a melting point of 230 to 3
The method for producing a polyamide resin according to claim 2, wherein the method is in the range of 40 ° C. 4. The polyamide resin has the following structural formula (II):
4. The method for producing a polyamide resin according to claim 2, which has one or more kinds of repeating units selected from (IV) to (IV). [Chemical 2] [Chemical 3] [Chemical 4] 5. The weight ratio of repeating units in the polyamide resin is (I) / (II) = 45 / 55-80 / 2.
0 or (I) / (III) = 20 / 80-80 / 20 or (I) / (IV) = 40 / 60-90 / 10, The manufacturing method of the polyamide resin of Claim 4 characterized by the above-mentioned. .