JP2001002781A - Production of polyamide pellet and polyamide fiber and molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a means for adjusting amino terminal content to a desired level in a short time. SOLUTION: An acid anhydride is continuously or intermittently supplied at a constant rate proportional to the flow rate of a polyamide while continuously supplying a polyamide, or an acid anhydride is collectively added to the polyamide in an amount proportional to the amount of the polyamide. The obtained mixture is melted, kneaded and pelletized.

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 polyamide pellets, fibers and molded articles.
More specifically, the present invention relates to a method for producing polyamide pellets having adjusted amino terminal group content, fibers and molded articles.

[0002]

2. Description of the Related Art When a polyamide is produced, the viscosity and the amount of terminal groups can be arbitrarily adjusted by adding a terminal group amount modifier. Examples of such terminal group amount modifiers include monocarboxylic acids,
A dicarboxylic acid, a monoamine, a diamine, or the like is used, and a method of adding these at the time of polymerization is generally performed.

For example, Japanese Patent Application Laid-Open No. 7-324223 discloses that hexamethylenediamine is added at the time of polymerization of polyhexamethyleneadipamide in order to obtain a predetermined terminal group concentration. However, when the addition amount of the terminal group amount adjusting agent increases, the time until the reaction between the terminal group amount adjusting agent and the polyamide terminal group is completed, and especially in the case of continuous polymerization, the terminal group amount adjusting agent Since the change in the amount of addition has a great effect, it has a great disadvantage in production activities. Further, when the terminal group amount regulator is added before or during the polymerization, when the condensed water in the polymerization system is removed, for example, a part of the diamine evaporates, which may be a factor that causes the quality to fluctuate.

Japanese Patent Application Laid-Open No. Hei 3-124726 discloses that in order to solve such a drawback, a diamine and a dicarboxylic acid, which are raw materials for forming a polyamide, are melt-mixed and a polymerization reaction is allowed to proceed. Granules,
It has been proposed to obtain desired viscosity and terminal group content by solid phase polymerization. However, the reaction between a diamine and a dicarboxylic acid is usually slow, and a solid-state polymerization step is indispensable, which increases the load on equipment and complicates the process, resulting in a long time until the desired polyamide is obtained. Disadvantage.

Japanese Patent Publication No. 43-544 discloses a method in which an intramolecular acid anhydride is blended into a chip and melt-spun to reduce the amount of amino terminal groups. The amount of intramolecular acid anhydride to be converted is large, and not only a large amount of intramolecular acid anhydride is required to obtain a yarn having the desired amino terminal group amount, but also the irritating odor due to the intramolecular acid anhydride to be increased. There is a disadvantage that it becomes intense.

Japanese Patent Application Laid-Open No. 1-229810 discloses a polyamide fiber in which the amount of amino terminal groups is adjusted by adding and reacting a liquid mixture comprising at least one compound of an acid or an acid anhydride and a dispersion medium during melt spinning. Although a production method is disclosed, there is a disadvantage that modification of the polyamide with a dispersion medium is inevitable.

[0007]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a means for adjusting a polyamide to a desired amount of amino terminal groups in a short time and at low cost.

[0008]

Means for Solving the Problems In order to solve the above problems, the method for producing polyamide pellets of the present invention mainly has the following constitution. That is, while continuously supplying the polyamide, the amount of the acid anhydride in proportion to the flow rate of the polyamide is continuously or intermittently supplied in a constant amount, or the amount of the acid anhydride in proportion to the amount of the polyamide is collectively supplied to the polyamide. This is a method for producing polyamide pellets, comprising melt-mixing and pelletizing after the addition. Further, the fiber of the present invention mainly has the following constitution. That is, it is a fiber obtained by melt-spinning the polyamide pellet obtained by the above production method. The molded article of the present invention mainly has the following configuration. That is, it is a molded product obtained by melt-molding the polyamide pellets obtained by the above production method.

[0009]

Embodiments of the present invention will be described below. Polyamides to which the production method of the present invention can be applied include, for example, ε-caprolactam, aminocaproic acid,
A polymer obtained by polycondensation of 11-aminoundecanoic acid or the like as a monomer, a diamine such as hexamethylenediamine, nonamethylenediamine, or metaxylylenediamine, and a dicarboxylic acid such as adipic acid, terephthalic acid, isophthalic acid, or sebacic acid. Or a mixture of these copolymers or a mixture of these copolymers. Among them, nylon 6 obtained by polycondensing ε-caprolactam can be preferably applied to the production method of the present invention. Further, the polyamide used in the production method of the present invention may be a polyamide in which the amount of some terminal groups in the polyamide is adjusted in advance by a known method.

The acid anhydride used in the present invention is, for example,
Examples thereof include succinic anhydride, benzoic anhydride, and maleic anhydride, and these can be used alone or in combination of two or more. Above all, succinic anhydride and / or benzoic anhydride can improve the color tone of the finally obtained polyamide,
preferable.

The acid anhydride may be added even if the polyamide is molten or partially or entirely unmelted. The polyamide can be added by the following method. That is, it is only necessary to directly add the polyamide to the flow path, and a known method can be used. For example, a method in which a polyamide melt is guided to a twin-screw extruder and a powdery acid anhydride is continuously added from a side feeder, and a method in which the acid anhydride is heated and melted and continuously added directly to a polyamide flow path using a plunger pump or the like. Is preferred. Further, the heating and melting of the acid anhydride is preferably performed in an atmosphere of an inert gas such as nitrogen. In such a case, deterioration of the color tone of the polyamide can be effectively prevented.

The acid anhydride may be added to a certain amount of polyamide in proportion to the amount of acid anhydride. For example, there is a method in which an acid anhydride in an amount directly proportional to the amount of the polyamide is directly added to a known polymerization can at a time.
Also in this case, it is preferable to add the acid anhydride in an atmosphere of an inert gas such as nitrogen in order to prevent the color tone of the polyamide from being deteriorated.

In the production method of the present invention, after the acid anhydride is added, the mixture is melt-mixed with the polyamide. Melt mixing may be performed by a known method. For example, melt mixing using a twin-screw extruder or a static mixer is preferable because uniform mixing can be performed.

The time required for melt mixing is from 0.5 minutes to 10 minutes.
Minutes, more preferably 1 minute to 5 minutes. When the time of the melt mixing is set in such a preferable range, the mixing of the polyamide and the acid anhydride is performed uniformly, and the variation in the amount of amino terminal groups in the polyamide is reduced. Further, the polyamide does not deteriorate due to shear heat generated by mixing.

The temperature of the melt mixing may be higher than the melting point of the polyamide, and is preferably 5 to less than the melting point of the polyamide.
The temperature does not exceed 0 ° C higher temperature. In such a preferable temperature range, at least a part of the polyamide is melted, the reaction with the acid anhydride proceeds easily, and the polyamide does not deteriorate.

Before and / or after the addition of the acid anhydride, a known light-proofing agent, antistatic agent, plasticizer, heat-resistant stabilizer,
Concealing agents such as titanium oxide, pigments, and other polymers (polyethylene, polyester, polypropylene, ABS resin, modified products thereof, and the like) can be added and mixed as needed within a range not to impair the object of the present invention.

It is necessary that the polyamide melt-mixed as described above is discharged from a die in a strand shape, cut, and once formed into chips. This suppresses variations in the amount of terminal groups due to the increase of the acid anhydride during remelting for spinning or molding.

The amount of the acid anhydride to be added is determined according to the target amount of amino terminal groups of the polyamide to be obtained. It is preferable to add them. Also, as a batch addition, 0.01 to the amount of polyamide
It is preferable to add it in the range of 1% by weight.

When the amount of the acid anhydride is within such a preferable range with respect to the flow rate of the polyamide, the amount of the amino terminal group can be sufficiently controlled, and the acid anhydride which has not been reacted during melt spinning or molding can be obtained. This can prevent the generation of offensive odor.

The relative viscosity of the 98% sulfuric acid solution having a concentration of 0.01 g / mL at 25 ° C. of the polyamide used in the present invention is 2.0 to 8.0, more preferably 2.2 to 6.0. It is preferably 0. When the relative viscosity is in such a preferred range, the mechanical properties are sufficiently exhibited, and melt spinning and melt molding are facilitated.

[0021]

EXAMPLES The present invention will be specifically described below with reference to examples. The relative viscosities and the amount of amino terminal groups described in Examples and Comparative Examples were measured by the following methods. (1) Relative viscosity [ηr] Using an Ostwald viscometer, a solution having a concentration of 0.01 g / ml
The relative viscosity of 8% sulfuric acid solution / 25 ° C. was measured. (2) Amount of amino terminal group [-NH ₂ ] (μmol / g) 0.5 g of sample was phenol / ethanol = 84/1.
It was dissolved in 25 ml of a 6% by weight mixed solution, and titrated with N / 50 N hydrochloric acid using thymol blue as an indicator to determine the amount of amino terminal groups.

(Example 1) [ηr] = 2.69, [—NH ₂ ]
= 6.13 (μmol / g) polyamide 6 chip
The twin screw extruder TEX-30 (manufactured by Japan Steel Works, Ltd.)
0 kg / hr, and melt-mixed for 1 minute while continuously supplying succinic anhydride to molten polyamide 6 having a polymer temperature of 235 ° C. so that the addition ratio becomes 0.03% by weight based on the flow rate of polyamide. After that, the mixture was discharged from the extruder in the form of a strand and formed into chips. Table 1 shows the evaluation results of the obtained polymers. The amount of amino end groups is reduced,
It can be seen that the amount of amino terminal groups could be adjusted.

[0023]

[Table 1]

(Example 2) [ηr] = 2.74, [—NH ₂ ]
= 5.22 (μmol / g) polyamide 6 chip
A polyamide 6 chip was prepared in the same manner as in Example 1 except that succinic anhydride was continuously added to the flow rate of the polyamide such that the addition ratio was 0.53% by weight, and the polymer temperature was 240 ° C. and melt-mixed. Obtained. The evaluation results of the obtained polymer are also shown in Table 1. It can be seen that the amount of amino terminal groups was reduced, and that the amount of amino terminal groups could be adjusted.

Example 3 A polyamide 6 chip was obtained in the same manner as in Example 1 except that benzoic anhydride was used as a terminal group amount regulator and the addition ratio was 0.14% by weight based on the flow rate of polyamide. Was. The evaluation results of the obtained polymer are also shown in Table 1. It can be seen that the amount of amino terminal groups was reduced, and that the amount of amino terminal groups could be adjusted.

Example 4 A polyamide 6 chip was obtained in the same manner as in Example 1 except that maleic anhydride was used as a terminal group amount regulator and the addition ratio was 0.50% by weight based on the flow rate of polyamide. Was. The evaluation results of the obtained polymer are also shown in Table 1. It can be seen that the amount of amino terminal groups was reduced, and that the amount of amino terminal groups could be adjusted.

(Comparative Example 1) Benzoic acid was used as a terminal group amount regulator, and the addition ratio was 0.6 to the polyamide flow rate.
Polyamide 6 was prepared in the same manner as in Example 1 except that the content was 5% by weight.
I got a chip. The evaluation results of the obtained polymer are also shown in Table 1. It can be seen that even if the addition ratio of benzoic acid is increased, the amount of amino terminal groups does not decrease sufficiently.

Comparative Example 2 A polyamide 6 chip was obtained in the same manner as in Example 1 except that isophthalic acid was used as a terminal group amount regulator and the addition ratio was 0.65% by weight based on the flow rate of polyamide. . The evaluation results of the obtained polymer are also shown in Table 1. It can be seen that even if the addition ratio of isophthalic acid is increased, the amount of amino terminal groups is not sufficiently reduced.

[0029]

According to the present invention, the obtained polyamide is less thermally degraded, and has excellent viscosity stability during melt spinning.
Fibers and molded products do not impair the appearance.

 ──────────────────────────────────────────────────続 き Continuing on the front page F term (reference) 4F070 AA54 AC40 AE03 BA02 BA05 DA05 FC04 FC05 4F071 AA54 AC09A AE22A BA01 4J001 DD13 EA06 EA14 EA16 EA17 EB08 EB09 EB36 EB37 EC08 EC09 EC47 EE27B GC05 GE15 GE13 AJA1 JA01 JA01 KK05

Claims (5)

[Claims] An amount of an acid anhydride proportional to the flow rate of the polyamide is continuously or intermittently supplied while the polyamide is continuously supplied, or an amount of the acid anhydride is proportional to an amount of the polyamide. A method for producing polyamide pellets, which comprises adding a mixture to a polyamide at a time, then melt-mixing and pelletizing. 2. The method according to claim 1, wherein the polyamide is nylon 6. 3. The method according to claim 1, wherein the acid anhydride is succinic anhydride and / or benzoic anhydride.
The method for producing a polyamide pellet according to any one of the above. 4. A fiber obtained by melt-spinning polyamide pellets obtained by the production method according to claim 1. 5. A molded product obtained by melt-forming polyamide pellets obtained by the production method according to claim 1.