JPH0718072A - Method for producing polyamide resin - Google Patents

Abstract

(57) [Summary] [Structure] In producing a crystalline copolyamide containing a hexamethylene terephthalamide unit, the relative viscosity (ηr) of a 1% sulfuric acid solution at 25 ° C. is 1.04 to
2.5 A method for producing a polyamide resin, which comprises producing a primary condensate, discharging the primary condensate under steam pressure, and then increasing the degree of polymerization. [Effect] By using the production method of the present invention, a crystalline copolyamide resin having good heat resistance can be easily produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
Further, the present invention relates to a method for producing a polyamide resin by producing a primary condensate from an aqueous solution of a salt and increasing the degree of polymerization thereof, and particularly to a method for producing a polyamide resin suitable for automobile parts and electric / electronic parts.

[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 products (Japanese Patent Laid-Open No. 59-161461), but the temperature of the engine room of an automobile due to recent technological innovation has been improved. With the rise in temperature and progress in microelectronics, there has been a demand for materials for ultra-thin molded products that can withstand use in higher temperature atmospheres. 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 copolyamide resin compositions containing terephthalic acid and isophthalic acid, or glass fiber reinforced products thereof have been proposed as copolyamide resin compositions that can withstand use under these high temperature atmospheres (special features). JP-A-59-161428 and JP-A-59-1554.
26, JP-A-59-53536, JP-A-6.
2-156130). As a production method, a method of carrying out a polymerization reaction in a solid state from a nylon salt to a polymer has been proposed (JP-A-62-20527). In addition, JP-A-4-502231 and JP-A-4-5
Japanese Patent No. 3835 discloses a method of synthesizing a primary condensation product of copolyamide and then further increasing the degree of polymerization.

[0005]

However, these terephthalic acid- and isophthalic acid-containing copolyamide resin compositions have a high melt viscosity when the number of terephthalic acid component units is large, and discharge is impossible by a usual melt polymerization method. Since the melting point of the polymer is close to the thermal decomposition temperature of the polymer, it has been decomposed or deteriorated during melt polymerization. In addition, the method of carrying out the polymerization reaction in the solid state from the nylon salt to the polymer is
There is a problem that the composition of the polymer is not stable. In addition, the method of further increasing the degree of polymerization after synthesizing the primary condensation product of the copolyamide often causes problems that the primary condensation product cannot be discharged and the quality of the obtained copolyamide is slightly unstable. Was.

[0006] Therefore, an object of the present invention is to stably produce 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.

[0007]

In view of the above situation, the inventors of the present invention have made earnest studies on a method for solving the above-mentioned problems, and as a result, made a primary condensate and put the primary condensate in a polymerization tank under steam pressure. The present invention has been achieved by discovering that a polymer having a high degree of polymerization can be efficiently and stably obtained by discharging while supplying water or steam and then increasing the degree of polymerization.

That is, according to the present invention, in producing a crystalline copolyamide containing a terephthalic acid amide structure, a primary condensate is synthesized under the condition of 150 ° C. to 350 ° C., and then water or steam is supplied to the polycondensate. The primary condensate is discharged under pressure of steam to obtain a primary condensate having a relative viscosity (ηr) of a 1% sulfuric acid solution at 25 ° C. of 1.04 to 2.5, and then the polymerization degree is further increased. Is a method for producing a polyamide resin.

The crystalline polyamide, which is a feature of the present invention, contains a terephthalic acid amide structural unit. This structure has a function of imparting rigidity and heat resistance to the obtained polyamide resin. Among them, those containing the structural unit (I), that is, the hexamethylene terephthalamide unit (hereinafter abbreviated as 6T) are preferable.

[Chemical 5] As this amount, if it is small, the heat resistance such as heat distortion temperature is lowered, the water absorption is increased, and if it is large, the heat resistance is improved, but since the molding temperature becomes high and the polymer is likely to undergo thermal decomposition. The lower limit of the content of the structural unit (I) in the polyamide resin is 20% by weight, and further 30
Weight% is preferable, and the upper limit of the content is 90% by weight, 80% by weight, 70% by weight, and further 60% by weight. From the viewpoint of heat resistance, the melting point of the obtained polyamide resin is preferably 230 ° C to 340 ° C, more preferably 270 to 340 ° C. This is because when the melting point is low, the heat resistance of the obtained resin is low, and when the melting point is too high, the polyamide tends to be thermally decomposed and deteriorated during molding.

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

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

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

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

In these copolymerized polyamides, for example, when attention is paid to the combination of 6T / 6I, the copolymerization ratio by weight is 55/45 or more, 60/40 or more, 80/20 or less, and 75/25. It is preferably used in the following range. Also, when paying attention to the combination of 6T / 66, the copolymerization ratio is 20/80 or more by weight, and further 30
A range of / 70 or more, 80/20 or less, 70/30 or less, and 60/40 or less is preferably used. Further, when focusing on the combination of 6T / 6, the copolymerization ratio is 45/55 or more by weight, 55/45 or more, 60/40 or more, 90/10 or less,
Furthermore, it is preferably used in the range of 80/20 or less. The copolymerization ratios of 6T / 6I, 6T / 66 and 6T / 6 polyamide here are such that the polymer melting point is approximately 230 ° C.
It relates to a polyamide in the range of 340 ° C.
The copolymerization ratios by weight of 6T / 6I, 6T / 66 and 6T / 6 are 55/45, 20/80 and 45/5, respectively.
When it is less than 5, it is not preferable in that the polymer melting point is lowered, the heat resistance such as the heat distortion temperature is lowered, and the water absorption is increased due to the 6T content reduction. Also, 6T / 6I, 6T
The copolymerization ratios of / 66 and 6T / 6 are 80/2, respectively.
When it is more than 0, 80/20, 90/10, 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, which is not preferable.

Further, the structural unit may be composed of three or more components, and in addition to the combination selected from the above (I) to (IV), a known polyamide unit may be contained. 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 crystalline copolyamide is not particularly limited, and a 1% sulfuric acid solution having a relative viscosity (ηr) at 25 ° C. of 1.8 to 5.0 can be arbitrarily used.

The primary condensate produced under the conditions of 150 ° C. to 350 ° C. according to the present invention means the aqueous solution of the above monomer or salt, charged into a pressure polymerization vessel usually used for the polymerization of nylon 66 and the like, under stirring conditions. Heat to 150 ° C-350 ° C.
The reaction temperature must be 150 ° C to 350 ° C, preferably 180 ° C to 340 ° C, more preferably 190 ° C.
~ 330 ° C. If the reaction temperature is lower than 150 ° C, the reaction time becomes long, which is not preferable.
If the temperature is higher than 0 ° C, foaming occurs due to thermal decomposition of the primary condensate, which is not preferable.

The pressure for producing the primary condensate of the present invention is
Usually 0 to 100 kg / cm ² -G, preferably 2 to 70
kg / cm ² -G, more preferably 5 to 60 kg / cm
Operated to keep at ^2- G.

The discharge of the primary condensate of the present invention must be carried out under pressure of steam. The water vapor pressure is not particularly limited, but is preferably in the range of 0 to 70 kg / cm ² -G, more preferably ^{2 to} 60 kg / cm ² -G, and further preferably 5 to 60 kg / cm ² -G. To be operated. The steam pressure needs to be maintained during discharge, and it is preferable to supply water or steam into the polymerization tank and maintain a constant steam pressure during discharge, or discharge while increasing the pressure. From the outside of the system, it is preferable to heat and supply the polymerization tank with a metering pump. The heating temperature is preferably 100
℃ or more, more preferably 150 ℃ or more. It is more preferable that the heating temperature is the saturated steam temperature of the pressure in the polymerization tank in order to maintain the stability of the polymerization state. Further, when steam is supplied from outside the system to the polymerization tank, the steam generation boiler must be higher than the pressure in the polymerization tank.

When steam pressure is not applied, for example, when nitrogen pressure is applied, it is not preferable because polymerization proceeds during discharge and discharge becomes unstable. In the usual polyamide polymerization, the total CO contained in the monomer and the salt
Generally, the raw materials are charged so that the amount of OH groups and the total amount of NH ₂ groups are equal, but in the present invention, the dicarboxylic acid component or the diamine component is made excessive at the time of charging the raw materials,
It is also possible to prepare a primary condensate having a large amount of terminal carboxyl groups or a large amount of terminal amino groups. That is, the dicarboxylic acid component or diamine component can be charged in an excess of 0 to 10 mol% with respect to the total number of moles of the constituent monomer and the total number of moles of the dicarboxylic acid component unit and the diamine component unit of the salt. The excess dicarboxylic acid component is not particularly limited, but examples thereof include aliphatic dicarboxylic acids such as adipic acid and sebacic acid, and aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid. Isophthalic acid and terephthalic acid are preferable, and terephthalic acid is particularly preferable. The excess diamine component is not particularly limited, and examples thereof include aliphatic diamines such as tetramethylenediamine and hexamethylenediamine. The amount of excess dicarboxylic acid or diamine added is 0 to
10 mol%, preferably 0.3 to 10 mol%, more preferably 0.5 to 8 mol%, still more preferably 0.5 to 7
It is necessary to be in the range of mol%. If the amount added exceeds 10 mol%, it is difficult to increase the degree of polymerization, which is not preferable. In order to facilitate the control of the degree of polymerization of the primary condensate and the degree of polymerization in the case 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 benzoic acid and stearic acid are preferable, and benzoic acid is particularly preferable. The degree of polymerization modifier is 0 to 0.1 times, preferably 0.0001 to 0.05 times the molar number of the constituent monomer monomers and the total molar number of the dicarboxylic acid component unit and the diamine component unit of the salt. Used.

The relative viscosity (ηr) of the primary condensate of the present invention must be 1.04 to 2.5, preferably 1.08 to 2.3, more preferably 1.08 to 2. It must be in the range of 1. Relative viscosity (ηr) is 1.
When it is less than 04, the polymerization time for increasing the degree of polymerization by melting becomes long, and when the relative viscosity is more than 2.5, the melt viscosity of the primary condensate becomes too high, which causes ejection failure, which is not preferable.

The apparatus for producing the primary condensate of the present invention is not particularly limited, and a well-known apparatus such as a batch reaction vessel or a 1 to 3 tank type continuous reaction apparatus can be used.

As the method for increasing the degree of polymerization of the primary condensate of the present invention, 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 using a primary condensate having a high 6T content and a high melting point, it is necessary to set the upper limit temperature to 370 ° C. or lower in order to prevent thermal decomposition and thermal deterioration of the polymer. As the melt extruder, 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 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 melters in series in order to increase the residence time and increase the degree of polymerization. The phosphorus-based catalyst is effective for increasing the degree of polymerization, and may be added if necessary.

The polymer having a high degree of polymerization can be solid-phase polymerized if necessary to further increase the degree of polymerization.

As the method for solid-phase polymerization of the primary condensate of the present invention, a method of applying pressure or normal pressure in the presence of an inert gas,
Alternatively, a method under reduced pressure, or a combination thereof may be used. The solid-state polymerization temperature is required to be 150 ° C to the melting point or lower, preferably 200 ° C to
Melting point -10 ° C, more preferably 220 ° C to melting point -15
℃. If the solid phase polymerization temperature is lower than 150 ° C., the reaction rate becomes slow, which is not preferable. The solid-phase polymerization time can be arbitrarily selected until the relative viscosity of the copolyamide used for ordinary molded articles is reached. The solid-state 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 rotary drum type and a double cone type solid-state polymerization apparatus.

A filler may 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, diatomaceous earth, clay,
Powdery or plate-like inorganic compounds such as gypsum, red iron oxide, graphite, titanium dioxide, zinc oxide, copper, stainless steel, and other polymer fibers (carbon fibers) are preferable, and glass fibers are preferable. Particularly preferred 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 the filler is usually 0 to 200 with respect to 100 parts by weight of the polyamide.
It is in the range of parts by weight, preferably more than 0 and in the range of 150 parts by weight, particularly preferably 10 to 100 parts by weight. When the blending ratio of the filler exceeds 200 parts by weight, the fluidity at the time of melting is deteriorated, it is difficult to injection-mold a thin-walled molded product, and the appearance of the molded product is deteriorated, which is not preferable.

There is no particular limitation on the method of adding the filler to the crystalline copolyamide of the present invention, and any known method can be used. Specific examples of the compounding method include a method in which the filler is dry blended with the crystalline copolyamide pellets, and the resulting mixture is melt-kneaded with a single-screw or twin-screw extruder. When the polymerization degree is increased in the melting machine, the method of adding the filler from the middle of the melting machine is preferable because of high production efficiency.

In the present invention, when the primary condensate is produced,
High degree of polymerization in the melt, compound or molding process, etc.
If necessary, a catalyst, a heat resistance stabilizer, a weather resistance stabilizer, a plasticizer, a release agent, a lubricant, a crystal nucleating agent, a pigment, a dye, another polymer and the like can be added. Examples of these additives include heat-resistant stabilizers (hydradphenol-based, hydroquinone-based, phosphite-based and substitution products thereof, copper iodide,
Potassium iodide, etc.), weathering stabilizer (resorcinol type, salicylate type, benzotriazole type, benzophenone type, hindered amine type, etc.), release agent and lubricant (montanic acid and its salt, its ester) , That h
Fester, stearyl alcohol, stearamide, various bisamides, bisurea and polyethylene wax), pigments (cadmium sulfide, phthalocyanine, carbon black, etc.), dyes (nigrosine, etc.), other polymers (other polyamides, Polyester, polycarbonate, polyphenylene ether, polyphenylene sulfide, liquid crystal polymer, polyether sulfone, AB
S resin, SAN resin, polystyrene, acrylic resin, polyethylene, polypropylene, ethylene / α-oleefin copolymer, ionomer resin, SBS, SEBS, etc.) can be mentioned.

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

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

The polyamide resin of the present invention includes switches,
Ultra-small slide switch, DIP switch, switch housing, lamp socket, binding band, connector,
Connector housing, connector shell, IC sockets, coil bobbins, bobbin covers, relays, relay boxes, condenser cases, internal parts of motors, small motor cases, gear cams. , Dancing pool,
Spacers, insulators, fasteners, buckles, wire clips, bicycle wheels, casters, helmets, terminal blocks, power tool housings, starter insulating parts, spoilers, canisters. -, 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, Integman manifold, Water pipe impeller, Engine roll damper, Clutch release, Speaker diaphragm, Heat resistant container, Microwave oven component, Rice cooker component, Printer -Electrical / electronic-related parts such as ribbon guides, automobile / vehicle-related parts, household / office electric appliance parts, computers- Communicating parts, facsimile copier related parts, machine related parts, it is effective for other various applications.

[0030]

The present invention will be described in more detail with reference to the following examples. The properties in the examples and comparative examples were measured by the following methods. 1) Melting point (Tm) Using DSC (PERKIN-ELMER7 type), samples 8 to 10
Let (T) be the temperature at which the maximum value of the melting curve obtained by measuring mg at a heating rate of 20 ° C./min. Sample 8-
10 mg is heated at a temperature rising rate of 20 ° C / min to obtain T + 20 ° C.
For 5 minutes, then at a temperature decrease rate of 20 ° C / min for 3 minutes.
After cooling to 0 ° C and holding at 30 ° C for 5 minutes, 20
Heat up to T + 20 ° C. at a heating rate of ° C./min. The maximum value of the melting curve at this time was defined as the melting point (Tm). 2) Relative viscosity (ηr) According to JIS K6810, 1 g of a sample was dissolved in 100 ml of 98% concentrated sulfuric acid, and the relative viscosity at 25 ° C was measured.

Example 1 Hexamethylene ammonium adipate (66 salt) 9.
00 kg, 6.72 kg of terephthalic acid, 7.02 kg of a 64.5 wt% aqueous solution of hexamethylenediamine and 6.40 kg of ion-exchanged water were charged in a batch pressure polymerization vessel of 0.10 m ³ (diamine component unit and dicarboxylic acid component unit). 1 mol% terephthalic acid was added to the total number of total moles of the above), and after sufficiently replacing the nitrogen, heating was continued. The temperature was raised to 255 ° C. over 3.5 hours with stirring, and the polymerization pressure was 40 kg / cm ² -G. Further, the temperature was maintained at 255 ° C. to 260 ° C. for 30 minutes to complete the reaction. The discharge was performed over 1 hour while supplying ion-exchanged water by a metering pump at a rate of 3 l / h and maintaining the water vapor pressure at 40 kg / cm ² -G. The viscosity of this primary condensate is ηr
= 1.3, melting point was 287 ° C. primary condensation product. After vacuum drying the obtained primary condensate at 100 ° C. for 24 hours,
A 30 mmφ bent type twin-screw extruder has a residence time of 200 seconds,
The maximum degree of resin temperature was 325 ° C, and the degree of polymerization was increased by melting. White pellets having a polymer viscosity ηr = 2.5 and a polymer melting point of 298 ° C. were obtained. The discharge of the primary condensate was stable, and finally a polyamide having a high molecular weight (ηr) and a high melting point could be obtained. The results are shown in Table 1.

Example 2 8.76 kg of terephthalic acid, 8.93 kg of a 64.5 wt% aqueous solution of hexamethylenediamine, 6.00 kg of ε-caprolactam and 6.66 kg of ion-exchanged water were added.
A 10 m ³ batch type pressure polymerization kettle was charged (2 mol% terephthalic acid with respect to the total moles of the monomer and dicarboxylic acid components and the diamine component was excessively charged), and after sufficient nitrogen substitution, heating was continued. It was 2 for 5 hours under stirring
After the temperature was raised to 70 ° C. and the polymerization pressure was 40 kg / cm ² -G, the reaction was further completed at 270 ° C. to 275 ° C. for 30 minutes. The ion pumped water is discharged by a metering pump for 2
It is supplied at a rate of 1 / h and the steam pressure is 45 kg / cm ² −.
It was carried out for 1 hour while being kept at G. The melting point of the obtained primary condensate was 300 ° C., and ηr was 1.5. This primary condensate was melt-polymerized to a high degree of polymerization by the method of Example 1 except for the conditions shown in Table 1. The discharge of the primary condensate was stable, and finally a polyamide having a high molecular weight (ηr) and a high melting point could be obtained. The results are shown in Table 1.

Examples 3 to 6 Table 1 shows the results of evaluation according to the method of Example 1 while changing the charged amount of the raw material, the steam pressure at the time of discharge, and the like.

In each of the methods of Examples 1 to 6, the discharge was stable, and a polyamide resin having a high degree of polymerization and a high melting point was obtained.

Comparative Examples 1-2 The relative viscosities of the primary condensates out of the range of the present application are shown in Table 1.
The same method as in Example 1 was carried out except for the conditions shown in. The primary condensation product having a low ηr (Comparative Example 1) does not achieve a sufficient degree of polymerization, while the ηr is high (Comparative Example 2).
The discharge of the primary condensate was not stable.

Comparative Example 3 The same procedure as in Example 1 was carried out except that the steam pressure during discharge of the primary condensate was set to 0 kg / cm ² -G, except for the conditions shown in Table 1. The primary condensate was discharged under nitrogen pressure,
Immediately after the start of discharge, it became unstable and the primary condensate was not discharged at all in about 2 minutes.

[0037]

[Table 1]

[0038]

The crystalline copolyamide having a high heat distortion temperature can be easily and stably produced by the method of the present invention.

Claims (7)

[Claims] 1. In producing a crystalline copolyamide containing a terephthalic acid amide structure, 150 ° C. to 350 ° C.
The primary condensate was synthesized under the condition of ° C, and then the primary condensate was discharged under pressure of steam while supplying water or steam, and the relative viscosity (ηr) of the 1% sulfuric acid solution at 25 ° C was 1.04 to A method for producing a polyamide resin, which comprises obtaining a primary condensate of 2.5 and then further increasing the degree of polymerization. 2. The method for producing a polyamide resin according to claim 1, wherein the terephthalic acid amide structure is the following repeating unit (I). [Chemical 1] 3. The method for producing a polyamide resin according to claim 2, wherein the polyamide resin contains 20 to 90% by weight of the structure of the repeating unit (I). 4. The melting point of the polyamide resin is 230 to 340.
It is in the range of ° C.
3. The method for producing a polyamide resin according to any one of 3 above. 5. The polyamide resin has the following structural formula (II)
The method for producing a polyamide resin according to any one of claims 2 to 4, which comprises one or more kinds of repeating units selected from (IV). [Chemical 2] [Chemical 3] [Chemical 4] 6. The weight ratio of repeating units in the polyamide resin is (I) / (II) = 55/45 to 80/2.
0 or (I) / (III) = 20 / 80-80 / 20 or (I) / (IV) = 45 / 55-90 / 10, The manufacturing method of the polyamide resin of Claim 5 characterized by the above-mentioned. . 7. The method for producing a polyamide resin according to claim 1, wherein the pressure of steam pressurization in discharging the primary condensate is more than 0 and 70 kg / cm ² -G or less.