JP3201115B2 - Method for producing polyamide resin - Google Patents

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 in which a primary condensate is formed from an aqueous solution of a monomer or a salt of a constituent unit and then the degree of polymerization is increased, and particularly suitable for automobile parts and electric / electronic parts. The present invention relates to a method for producing a polyamide resin.

[0002]

2. Description of the Related Art Polyamide resins are used in the automotive field,
It has been widely used in the electric and electronic fields.

Conventionally, these molded articles have been made of nylon 6 or nylon 66 reinforced with glass fiber (Japanese Patent Application Laid-Open No. 59-161461). With the development of microelectronics, there has been a demand for a material for a molded article that can withstand use in a high-temperature atmosphere. However, the melting points of nylon 6 and nylon 66 are 220
C. and 260.degree. C., and even when reinforced with glass fibers, the limit of the heat distortion temperature is the melting point, respectively.

Recently, many polyamide resins having terephthalic acid and isophthalic acid components and glass-reinforced products thereof have been proposed as polyamide resin compositions which can withstand use in such high-temperature atmospheres (Japanese Patent Laid-Open No. 59-1984). 1
No. 61428, JP-A-59-155426,
JP-A-59-53536 and JP-A-62-1561.
No. 30). As a method for producing these compounds, a method of carrying out a polymerization reaction in a solid state from a nylon salt to a polymer (Japanese Patent Application Laid-Open No. 62-20527) has been proposed, but there is a problem that the composition of the polymer is not stable. was there. As another method, a method of synthesizing a primary condensate and further increasing the degree of polymerization with a melt extruder (JP-A-5-4368)
No. 1, JP-A-4-53825), a method of synthesizing a primary condensate and increasing the degree of polymerization by solid-phase polymerization (JP-A-4-50231), and the like.

[0005]

However, in the method of synthesizing the primary condensate and then increasing the degree of polymerization while melting, it is often difficult to obtain a sufficient degree of polymerization during the melting in the step of increasing the degree of polymerization. In addition, phenomena such as solidification of the primary condensate near the inlet of the melter and ejection of polyamide from the vent of the melter have occurred, making it difficult to stably obtain a polymer having a high degree of polymerization. Also, in the method of increasing the degree of polymerization by solid phase polymerization after synthesizing the primary condensate, there has been often seen a problem that the reactants are fixed at the time of increasing the degree of polymerization and the reaction cannot be performed uniformly.

[0006]

In view of the above circumstances, the present inventors have developed a method for stably producing a 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 intensive studies on the primary condensate, after the primary condensate was synthesized, the primary
By adjusting the water content of the primary condensate by a step of contacting a water stream with the condensate, the present inventors have found that a polymer having a high degree of polymerization can be efficiently obtained by increasing the degree of polymerization, and that a stable polymer having a high degree of polymerization can be obtained. . That is, the present invention provides a compound represented by the following structural formula (I)

Embedded image Wherein the relative viscosity at 25 ° C. of a 1% sulfuric acid solution is 1.04 to 2.2 by a primary condensate synthesis step at 150 to 350 ° C. 5 after obtaining the primary condensate, the primary condensate continuously discharged from the reaction tank
A method of adjusting the water content of the primary condensate to 0.03 to 10% by weight by a step of bringing the primary condensate into contact with a water stream to further increase the degree of polymerization. ".

Hereinafter, the present invention will be described in detail.

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 2
The temperature is preferably 30 ° C to 340 ° C, and more preferably 270 ° C to 340 ° C.
It is preferable that it is -340 degreeC. This is because if the melting point is low, the heat resistance of the obtained resin is low, and if the melting point is too high, there is a problem that the polyamide is easily decomposed and deteriorated during molding.

Here, the obtained polyamide resin is preferably a polyamide having one or more kinds of repeating units selected from the following structures (II) to (IV) in addition to the 6T component.

[0010]

Embedded image A hexamethylene isophthalamide unit represented by the following formula (hereinafter referred to as 6I).

[0011]

Embedded image A hexamethylene adipamide unit (hereinafter referred to as 66)
Shown).

[0012]

Embedded image A caproamide unit represented by the following (hereinafter, referred to as 6).

In these copolymerized polyamides, for example, in the case of two components, the copolymerization ratio of 6T / 6I is 45/55 to 80/20 by weight, preferably 55/45 to 80/20.
80/20, more preferably in the range of 60/40 to 75/25. In 6T / 66, the copolymerization ratio is 20/80 to 80/20 by weight, preferably 30/7.
0-70 / 30, more preferably 30 / 70-60 / 4
Used in the range of 0. In 6T / 6, the copolymerization ratio is 40/60 to 90/10 by weight, preferably 55/60.
45-85 / 15, more preferably 60 / 40-80 /
Used in the range of 20. 6T / 6I, 6T here
The copolymerization ratios of / 66 and 6T / 6 polyamides relate to polyamides having a polymer melting point in the approximate range of 230 ° C to 340 ° C. The copolymerization ratio by weight of 6T / 6I, 6T / 66 and 6T / 6 was 45 /
If it is less than 55, 20/80, or 40/60, a decrease in heat resistance such as a heat distortion temperature due to a decrease in polymer melting point,
And the increase in water absorption due to the decrease in 6T content is not preferred. The copolymerization ratio of 6T / 6I, 6T / 66 and 6T / 6 is 80/20, 80/20, 90/1, respectively.
When it is more than 0, the melting point of the polymer is increased and the heat resistance is improved, but the processing temperature is increased and the polymer is thermally decomposed.

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.

In the present invention, the degree of polymerization of the obtained polyamide resin is not particularly limited, but the relative viscosity (hereinafter referred to as ηr) of a 1% sulfuric acid solution at 25 ° C. is usually 1.8 to 5.0. Any of these can be used.

In the present invention, as a raw material of the first condensate synthesized first, generally, monomers such as cyclic amide, aminocarboxylic acid, dicarboxylic acid, and diamine;
Further, a salt comprising a dicarboxylic acid and a diamine is used. These raw materials can be supplied as a solution such as water. In particular, in the polyamide resin which is a feature of the present invention, (I) a raw material for providing hexamethylene terephthalamide units (hereinafter referred to as a terephthalic acid component) generally includes terephthalic acid and hexamethylenediamine, or a salt of both. It is preferably used.

The polymerization reaction for synthesizing the primary condensate includes:
Charge one or more types of raw materials exemplified above into a pressure 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 feed the raw material mixed aqueous solution as a raw material in a concentration of 50% or more, preferably 65% or more. There is no particular limitation on the method of charging the raw materials, and it is also possible to collectively supply the raw materials before heating or to supply the raw materials after heating.

The pressurized reaction tank for synthesizing the primary condensate is not particularly limited, and a known reaction vessel such as a batch reactor or a 1 to 3 tank continuous reaction apparatus can be used.

The reaction temperature for producing the primary condensate of the present invention must be 150 to 350 ° C., preferably 1 to 350 ° C.
80-340 degreeC, More preferably, it is 190-340 degreeC. If the reaction temperature is lower than 150 ° C., the reaction time is undesirably long. On the other hand, if the reaction temperature is higher than 350 ° C., foaming due to thermal decomposition of the primary condensate or generation of a gel-like foreign substance becomes remarkable, which is not preferable.

The pressure in the primary condensate synthesis step is usually from 0 to
100kg / cm ² -G, preferably 2~70kg / cm ² -G, and more preferably is operated to maintain the 5~60kg / cm ² -G. The primary condensate can be discharged from the reactor in a molten state at a temperature of 150 to 350 ° C. in order to give a significant freezing point depression due to the presence of a small amount of water.

Ηr of a 1% sulfuric acid solution of the primary condensate at 25 ° C. must be 1.04 to 2.5, preferably 1.08 to 2.3, more preferably 1.08 to 2.3.
2.1. The relative viscosity is 1.
When the ratio is less than 04, the reaction time in the step of increasing the degree of polymerization becomes long, and when the relative viscosity is more than 2.5, the melt viscosity of the primary condensate becomes too high, which causes an ejection failure.

In ordinary polyamide polymerization, it is general to charge the raw materials so that the total carboxyl group amount and the total amino group amount contained in the monomer and the salt are equal, but in the present invention, the raw materials are charged. It is also possible to prepare a primary condensate having a large amount of carboxyl groups or amino groups by adding a dicarboxylic acid component or a diamine component during charging. A preferred charging ratio is to charge the dicarboxylic acid component or the diamine component in an excess of 0 to 10 mol% based on the total number of moles of the constituent monomer. 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, and examples thereof include an aliphatic dicarboxylic acid component such as adipic acid and sebacic acid, and an aromatic dicarboxylic acid such as terephthalic acid and isophthalic acid. The diamine component is not particularly limited, and examples thereof include aliphatic diamines such as tetramethylene diamine and hexamethylene diamine. When the dicarboxylic acid component or the diamine component is excessively charged, a shortage of the diamine component or the dicarboxylic acid component can be added in the step of increasing the degree of polymerization in the melt to control the polymerization rate.

Further, in order to easily control 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 or a monocarboxylic acid compound is 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 the total number of dicarboxylic acid component units and diamine component units of the salt. Used.

The method of discharging from the reaction tank of the present invention is as follows.
It is preferable to discharge under a pressure of 100 kg / cm ² -G,
Or by using the pressure during the polymerization reaction as it is or N ₂
It is appropriate to pressurize to an arbitrary pressure with an inert gas such as the above and discharge. Further, in the case where the discharge time is long or a primary condensate having a large increase in viscosity during discharge is discharged, water or steam may be supplied to the reaction tank, and discharge may be performed under steam pressurization. In addition, a metering pump such as a gear pump can be used to adjust the discharge amount. The primary condensate discharged from the reaction tank is continuously discharged onto a steel belt or cooling drum, etc.
It is also possible to continuously charge the pulverizer through the following steps .

Next, the adjustment of the water content of the primary condensate, which is a feature of the present invention, will be described. Here, the moisture content means the moisture content-based moisture content, and also means the moisture content in the primary condensate immediately before the step of increasing the degree of polymerization. The water content of the primary condensate is 0.03
To 10% by weight, preferably 0.1%
-7% by weight, more preferably 0.5-5% by weight. If the water content is 0.03% by weight or less, the sealing of the melter is insufficient in the step of increasing the degree of polymerization in the molten state, and the polymer is liable to be oxidized and colored. Absent. If the water content is 10% by weight or more, the degree of polymerization may not be sufficiently increased in the step of increasing the degree of polymerization in the molten state, or the primary condensation may occur in a supply portion such as a supply hopper or a supply barrel of a melt extruder. In some cases, the product solidifies in a clay-like manner and cannot be supplied. In addition, since the degassing from the melt extruder becomes insufficient, a phenomenon in which the polymer is ejected from the vent portion (vent up) may occur. It is not preferable. In addition, even when the degree of polymerization is increased by solid-phase polymerization, when the water content is high, the problem that the reactants are fixed and the reaction cannot be carried out uniformly often occurs, which is not preferable.

The method for adjusting the water content of the primary condensate includes:
A method is used in which the primary condensate is continuously discharged from a reaction tank to a steel belt, a cooling drum, or the like, and is brought into contact with a water stream radiated from a shower nozzle, a spray gun, or the like . This is advantageous in terms of the ease of controlling the water concentration, the efficiency of the amount of heat used, and the time required for the process . In this case, as the amount of water in contact, in order to control the moisture content, the discharge speed of the primary condensate, the primary condensate temperature at the time of discharge,
In addition, although it is determined in view of the conditions of the process such as pulverization and storage from contact with water to the step of increasing the degree of polymerization, it is preferably 2 times or less and 5% or more of the weight of the primary condensate. The shape of the water flow may be continuous from the water emission port to contact with the primary condensate, or may be water droplets or mist.

Next, the degree of polymerization of the primary condensate is increased to form a polyamide resin. As a method for increasing the degree of polymerization of the primary condensate, a method in which the primary condensate is melted using a melting machine, a method using solid-state polymerization, a method using both melting and solid-phase polymerization, and the like can be used.

When a melting machine is used, 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 containing a large amount of terephthalic acid component and having a high melting point is used, the upper limit temperature must be 370 ° C. or lower in order to prevent thermal decomposition and thermal degradation of the polymer. As the melting machine, an extruder and a kneader can be used, but a twin-screw extruder and a twin-screw kneader are preferable.

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

As a method for increasing the degree of polymerization by solid-phase polymerization from the primary condensate, a method of increasing the pressure or normal pressure in the presence of an inert gas, a method of reducing the pressure, or a combination thereof. You can also. In the solid phase polymerization method, the temperature needs to be from 130 ° C. to the polymer melting point.
Preferably it is 170 degreeC-(melting point -10 degreeC), More preferably, it is 200 degreeC-(melting point -15 degreeC). If the solid-state polymerization temperature is lower than 130 ° C., the reaction rate is undesirably low. The solid-phase polymerization time can be selected as desired until the relative viscosity of the polyamide resin used for a general molded article becomes the same. The solid-state polymerization apparatus is not particularly limited, and any known method can be used. Specific examples of the solid-phase polymerization apparatus include a kneader, a twin-screw paddle, a tower type, a rotary 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. Fillers are glass beads, talc, kaolin, wollastonite, mica,
Silica, alumina, silicate earth, clay, gypsum, red iron, graphite, titanium dioxide, zinc oxide, copper,
Examples thereof include powdery or plate-like inorganic compounds such as stainless steel, and other polymer fibers (carbon fibers), and preferably glass fibers. As the glass fiber, glass fiber is generally used as a reinforcing agent such as a thermoplastic resin or a thermosetting resin. Particularly preferred is a glass roving or a glass chopped strand made of a continuous long fiber strand having a diameter of about 3 to 20 μm. , Glass thread and the like. The compounding ratio of such a filler is generally in the range of 0 to 200 parts by weight per 100 parts by weight of the polyamide resin, preferably 0 to 200 parts by weight.
Over 150 parts by weight, particularly preferably from 10 to 1 part by weight.
00 parts by weight. If the mixing ratio of the filler exceeds 200 parts by weight, the fluidity at the time of melting becomes poor, and not only is it difficult to injection-mold a thin-walled molded product, but also the appearance of the molded product is undesirably deteriorated.

The method of blending the filler with the polyamide resin of the present invention is not particularly limited, and any known method can be used. Specific examples of the compounding method include a method in which a filler is dry-blended with polyamide resin pellets and melt-kneaded with a single screw or twin screw extruder. When increasing the degree of polymerization with an extruder,
A side feed method in the middle of the extruder is preferable because of high production efficiency.

In the present invention, when a primary condensate is synthesized, a catalyst, a heat stabilizer, a weathering stabilizer, a plasticizer or the like may be used, if necessary, for increasing the degree of polymerization of the melt, increasing the degree of polymerization of the solid phase polymerization, compounding or molding steps. Agent, release agent, lubricant, nucleating agent, pigment,
Dyes, other polymers and the like can be added to the polyamide resin.

These additives include heat stabilizers (hindered phenols, hydroquinones, phosphites and their substitutes, copper iodide, potassium iodide, etc.) and weather resistance stabilizers (resorcinol, salicylate, etc.). Benzotriazoles, benzophenones, hindered amines, etc.), release agents and lubricants (montanic acid and its salts, esters, half esters thereof, stearyl alcohol, stearamide, polyethylene wax, etc.), pigments (cadmium sulfide, phthalocyanine) Compounds, such as carbon black), 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.).

The compound of the additive is selected from the viewpoint of productivity.
It is more preferable to carry out the polymerization simultaneously or continuously with increasing the degree of polymerization in the melter.

To improve the color tone of the polyamide resin, the addition of an antioxidant is effective, and in particular, the addition of a sodium hypophosphite and a hindered phenol-based antioxidant is preferred. Sodium hypophosphite is also effective in promoting the degree of polymerization of the primary condensate.

The polyamide resin of the present invention is used for switches, micro slide switches, DIP switches, switch housings, lamp sockets, binding bands, connectors, connector housings, connector shells, IC sockets, coil bobbins, bobbin covers, relays. , Relay box, condenser case, motor internal parts, small motor case, gear cam, dancing pulley,
Spacers, insulators, fasteners, buckles, wire clips, bicycle wheels, casters,
Helmet, terminal block, power tool housing, starter insulation, spoiler, canister, radiator tank, chamber tank, reservoir tank, fuse box, air cleaner case, air conditioner fan, terminal housing, wheel cover, intake / exhaust pipe, bearing Retainer, cylinder head cover, intake manifold, water pipe impeller, clutch release, speaker diaphragm, heat-resistant container,
Electric / electronic related parts such as microwave oven parts, rice cooker parts, printer ribbon guides, automobile / vehicle related parts, home appliance / office electric product parts, computer related parts, facsimile / copier related parts, machine related parts, It is useful for various other uses.

[0038]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which, however, are not intended to limit the scope of the present invention. Various properties in the examples and comparative examples were measured by the following methods.

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

2) Moisture content Measured according to the method of JIS-K6810-4.3.

3) The physical properties of the molded article were measured by the following methods.

Tensile strength: ASTM-D638 Flexural strength: ASTM-D790 Flexural modulus: ASTM-D790 Izod impact strength: ASTM-D256 Thermal deformation temperature (HDT): ASTM-D648 Load 4.6 kgf / cm ² Load 18.6 kgf / cm ² <Example 1> 15.0 kg of hexamethylene ammonium adipate (66 salt), 10.0 kg of terephthalic acid and hexamethylene diamine salt (6T salt), and benzoic acid 11
3 g and 10.0 kg of ion-exchanged water were charged into a 0.1 m ³ batch-type reaction tank, and after sufficient nitrogen substitution, heating was continued under a steam pressure of 17.5 kg / cm ² -G. The temperature was raised to 285 ° C. over 3.5 h with stirring to complete the reaction.
The primary condensate was discharged at a rate of 50 kg / h from a lower part of the reaction tank onto a steel belt having a length of 8 m and a width of 0.5 m. At this time, water was emitted to the primary condensate at a rate of 30 kg / h using a spray gun. The primary condensate from the steel belt was continuously supplied to a Hosokawa Micro DKA06 rotary hammer mill to obtain a primary condensate consisting of a white powder having an average particle diameter of 1 mm. The viscosity of the obtained primary condensate is ηr =
The melting point was 1.35, the melting point was 283 ° C., and the water content was 2.5% by weight. This primary condensate is converted to 260 mm by a 30 mmφ vent type (degree of vacuum = −700 to −720 mmHg) twin screw extruder.
Melt extrusion was carried out at a temperature of from ℃ to 335 ° C to increase the degree of polymerization. As a result, a polyamide resin composed of white pellets having a polymer viscosity ηr of 2.55 and a polymer melting point of 282 ° C. was obtained.

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

Example 2 11.85 kg of an 85% by weight aqueous solution of ε-caprolactam, 5.8 kg of terephthalic acid,
6.33k of a 65% by weight aqueous solution of hexamethylenediamine
g, benzoic acid (155 g) and ion-exchanged water (4.6 kg) were charged into a 0.1 m ³ batch-type pressurized reaction tank, and after sufficient nitrogen substitution, heating was continued under a steam pressure of 20 kg / cm ² -G. Was. After raising the temperature to 270 ° C. over 2.5 hours with stirring, a 60% by weight aqueous 6T salt solution 1 heated to 160 ° C.
While supplying 3.9 kg to the reaction tank at a rate of 15 kg / h by a metering pump, the temperature was further increased from 270 ° C. to 300 ° C. over 1 hour to complete the synthesis reaction of the primary condensate. It was discharged onto the same steel belt as in Example 1 at a rate of 50 kg / h. At this time, water was sprayed on the discharge at a rate of 40 kg / h using a shower nozzle. This primary condensate was continuously supplied to a pulverizer UG280 manufactured by Horai Co., Ltd. to obtain a primary condensate consisting of a white powder having an average particle diameter of 2 mm.
The melting point of this primary condensate was 296 ° C., ηr was 1.43, and the water content was 4.3% by weight. By subjecting this primary condensate to a high degree of polymerization by melt extrusion in the same manner as in Example 1, a polyamide resin was obtained. Further, compounding and molding were performed, and the molded product was evaluated. The results are shown in Table 1.

Example 3 12.5 kg of hexamethyleneammonium adipate (66 salt), 12.5 kg of a salt of terephthalic acid and hexamethylenediamine (6T salt), 112 g of benzoic acid and 16.6 kg of ion-exchanged water were added.
After charging into a 1 m ³ batch-type reaction vessel and sufficiently purging with nitrogen, heating was continued under a steam pressure of 40 kg / cm ² -G.
The temperature was raised to 260 ° C. over 3 hours with stirring, and further 270 ° C.
After the reaction was completed by holding at 1 ° C. for 1 hour, discharge, water emission and pulverization were performed under the same conditions as in Example 1. As a result, a primary condensate consisting of a white powder having an average particle size of 1 mm was obtained. The viscosity of this primary condensate is ηr = 1.30, and the melting point is 295.
° C, the water content was 5.2% by weight. The degree of polymerization of the primary condensate was increased by melt extrusion in the same manner as in Example 1 to obtain a polyamide resin. Further, compounding and molding were performed in the same manner as in Example 1, and the molded product was evaluated.
Table 1 shows the results.

Comparative Example 1 After the primary condensate was polymerized under the same conditions as in Example 1, ion-exchanged water was poured into a stainless steel container having a length of 1.5 m, a width of 1.5 m and a depth of 0.6 m. The mixture was discharged into water with stirring to obtain a white precipitate. After dehydration with a vertical centrifugal dehydrator equipped with a filter cloth, the resultant was dried with a hot air dryer at 80 ° C. for 3 hours to obtain a primary condensate. The water content of the primary condensate was 12.3% by weight.

An attempt was made to increase the degree of polymerization of the primary condensate by melt extrusion under the same conditions as in Example 1. However, after operating for about 15 minutes, the primary condensate solidified into a clay at the supply barrel of the melt extruder. Supply became unavailable.

<Comparative Example 2> After performing the primary condensate synthesizing step in the same manner as in Example 1, the product discharged from the reaction tank was vacuum-dried at 130 ° C. for 48 hours using a vacuum drier to obtain a primary condensate. I got The water content of the obtained primary condensate is 0.02
% By weight. This primary condensate was melt-extruded under the same conditions as in Example 1 to increase the degree of polymerization to obtain a pellet-shaped polyamide resin. The obtained resin was colored yellow.

[0049]

[Table 1]

[0050]

By controlling the water content of the primary condensate, it is possible to solve problems such as inability to supply in the step of increasing the degree of polymerization and coloring of the polymer, and therefore, it has a terephthalic acid component having good heat resistance. A polyamide resin can be efficiently and stably produced.

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C08G 69/00-69/36

Claims (4)

(57) [Claims] (1) The following structural formula (I): Wherein the relative viscosity at 25 ° C. of a 1% sulfuric acid solution is 1.04 to 2.2 by a primary condensate synthesis step at 150 to 350 ° C. 5 after obtaining the primary condensate, the primary condensate continuously discharged from the reaction tank
A method of adjusting the water content of the primary condensate to 0.03 to 10% by weight by a step of bringing the primary condensate into contact with a water stream to further increase the degree of polymerization. 2. The polyamide resin having a melting point of 230 to 34.
2. The method according to claim 1, wherein the temperature is within a range of 0.degree.
A method for producing the polyamide resin as described above. 3. The polyamide resin has the following structural formula (II):
The method for producing a polyamide resin according to claim 1 or 2, wherein the method comprises one or more types of repeating units selected from (IV) to (IV). Embedded image Embedded image Embedded image 4. The ratio of repeating units in the polyamide resin is (I) / (II) = 45/55 to 80/2 by weight.
The method for producing a polyamide resin according to claim 3, wherein 0 or (I) / (III) = 20/80 to 80/20 or (I) / (IV) = 40/60 to 90/10. .