JP2001098067A - Process for producing polyhexamethylene adipamide resin and molding comprising polyhexamethylene adipamide resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for producing a stabilized nylon 66 resin having a small dispersion of the contents of terminal groups after the polymerization. SOLUTION: This process comprises mixing a dicarboxylic acid having a solubility of at most 1 g/100 g of water at 15 deg.C with an aqueous solution of adipic acid and hexamethylenediamine and adding a diamine and/or a dicarboxylic acid to the mixture so that the pH of the mixed solution may satisfy the relationships: 7.0 <= pH of the mixture <= 8.0.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polyhexamethylene adipamide resin (hereinafter, referred to as a nylon 66 resin) and to molded articles and fiber products obtained therefrom. More specifically, the present invention relates to a method for producing a nylon 66 resin for reducing the variation in the amount of terminal groups when a copolymer monomer component having low solubility in water is polycondensed, and a molded article of the nylon 66 resin obtained by the method.

[0002]

2. Description of the Related Art When dyeing nylon 66 for fiber after spinning, the amount of carboxyl terminal groups and amino terminal groups of the polymer greatly affects the dyeability of the yarn, and if the amount of polymer terminal groups varies, light dyeing, It causes uneven dyeing such as deep dyeing. Therefore, when polymerizing the nylon 66 for fibers, it is important to adjust the amount of terminal groups.

When a dicarboxylic acid or a diamine is copolymerized with nylon 66, a salt of a dicarboxylic acid and a diamine is added so that the amount of terminal groups does not largely fluctuate, and then added to a salt of adipic acid and hexamethylenediamine. It is common to start. Conventionally, the salt reaction of the copolymerization component is performed in a separate step before adding to the aqueous salt solution of adipic acid and hexamethylenediamine, and then the addition is performed. Therefore, a reactor for performing a salt reaction of the copolymer component is required,
Space and cost for installing the salt reaction equipment are required.
In addition, dicarboxylic acid whose solubility in 100 g of water at 15 ° C. is 1 g or less has a low solubility in water, so that the salt reaction is performed in a slurry state of the dicarboxylic acid, so that it takes time to prepare the slurry. there were.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a method for producing a stable nylon 66 resin by reducing the variation in the amount of terminal groups at the end of polymerization. It is to provide.

[0005]

Means for Solving the Problems In order to solve the above problems, a method for producing a polyhexamethylene adipamide resin of the present invention mainly has the following constitution. That is, water 10 at 15 ℃
After mixing a dicarboxylic acid having a solubility of 0 g or less with an aqueous solution of adipic acid and hexamethylene diamine, the diamine and / or the diamine are mixed so that the pH satisfies the formula (I).
Alternatively, a method for producing a polyhexamethylene adipamide resin, comprising adding a dicarboxylic acid for pH adjustment and polycondensing the mixed solution. 7.0 ≦ mixed solution pH ≦ 8.0 (I) Here, in the present invention, the term “pH” refers to a value obtained by diluting the above mixed solution to 10% by weight and then measuring the temperature in a constant temperature state of 30 ± 1 ° C. PH measurement value.

A molded article made of the polyhexamethylene adipamide resin of the present invention mainly has the following constitution.
That is, it is a molded article made of the polyhexamethylene adipamide resin obtained by the method for producing the polyhexamethylene adipamide resin. Here, the molded article includes a fiber product.

[0007]

DETAILED DESCRIPTION OF THE INVENTION In the present invention, nylon 66 is used.
When copolymerizing the above-mentioned specific dicarboxylic acid, in an aqueous solution of adipic acid and hexamethylenediamine as monomer components, the pH of the mixed solution after adding the dicarboxylic acid, so as to be in the range of 7.0 to 8.0. To which diamine or dicarboxylic acid is added, and preferably 7.2 to 7.9, more preferably 7.3 to 7.8.

When the pH of the mixed solution after the addition of the dicarboxylic acid is less than 7.0, the amount of amino terminal groups becomes small and the amount of terminal groups fluctuates, and at the time of dyeing after spinning, light dyeing and uneven dyeing occur. There is a problem. On the other hand, when the pH exceeds 8.0, the amount of amino terminal groups becomes small and the amount of terminal groups fluctuates at the same time. When dyeing after spinning, polycondensation has a problem of deep dyeing and uneven dyeing. It is necessary to start the polycondensation reaction in the state of a mixed solution of an acid and hexamethylenediamine and a salt of a dicarboxylic acid and a diamine serving as a copolymerization component. The mixed solution may be pre-concentrated by a concentrating device before being charged into the polymerization device. Before the start of the polycondensation, a salt reaction may be carried out in a polycondensation reactor.

[0009] The addition of the diamine is controlled by a pH meter, a conductivity meter or the like in order to obtain a stable pH at the time of performing the salt reaction, preferably by measuring instruments of the reaction apparatus. It is desirable that the reaction method be capable of feeding back the amount of addition from the value.

The addition of the dicarboxylic acid and the addition of the diamine to the aqueous solution of adipic acid and hexamethylenediamine is preferably performed under a nitrogen seal. This is because, when performed in the presence of oxygen, the monomer component may react with oxygen in the air due to the heat of the salt reaction between the dicarboxylic acid and the diamine, causing oxidative deterioration.

The concentration of the adipic acid and hexamethylenediamine in the aqueous solution before the addition of the copolymer component is 20% by weight in view of the solubility of the copolymer component and the concentration efficiency during polymerization.
It is preferable to polymerize after concentrating to 65% by weight or less, more preferably 40% by weight or more and 60% by weight or less. When the content is 20% by weight or more, the dicarboxylic acid as a copolymer component is sufficiently dissolved, and the amount of water is not too large, so that a long time is not required for concentration before charging into a polymerization apparatus. When the content is 65% by weight or less, the concentration of the aqueous salt solution of adipic acid and hexamethylenediamine is appropriate.
There is no need to do more. Therefore, when a salt reaction with a copolymer component is performed by adding a diamine under normal pressure, evaporation of water, a diamine component, and the like hardly occurs, and the concentration and pH can be easily controlled.

[0012] The amount of the copolymer component added is at least 90% by weight of hexamethylene adipamide repeating units, at most 10% by weight of dicarboxylic acid repeating units, and further at least 95% by weight of hexamethylene adipamide repeating units. The dicarboxylic acid repeating unit is preferably at most 5% by weight, particularly preferably at least 97% by weight of hexamethylene adipamide repeating unit, at most 3% by weight of the dicarboxylic acid repeating unit.
When the dicarboxylic acid repeating unit of the polymer is 10% by weight or less, the properties as polyhexamethylene adipamide do not change due to the influence of the copolymer.

The dicarboxylic acid used in the present invention, 15
The solubility at 100 ° C. in 100 g of water is 1 g or less. 1g solubility in 100g water at 15 ℃
When a dicarboxylic acid exceeding the above is used, the solubility is high, so that the addition of a dicarboxylic acid and the addition of a diamine to an aqueous solution of adipic acid and hexamethylenediamine as shown in the present invention is less necessary.

A solubility in 100 g of water at 15 ° C. is 1
g or less of the dicarboxylic acid is, for example, sebacic acid,
Dodecanediaside, phthalic acid, isophthalic acid, terephthalic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-
Examples thereof include cyclohexanedicarboxylic acid and 2,6-naphthalenedicarboxylic acid, preferably sebacic acid, isophthalic acid, and terephthalic acid, and more preferably isophthalic acid.

The diamine may be a known diamine, such as hexamethylenediamine, 1,4-diaminobutane,
There are 5-diaminopentane, 1,6-diaminohexane (hexamethylenediamine), 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, isophoronediamine, and the like, and preferably hexamethylenediamine.

The pH-adjusting dicarboxylic acid to be added to the mixed solution for pH adjustment may be a known one, and preferably adipic acid.

The polymerization of the nylon 66 resin may be performed by a known method. At this time, in the present invention, nylon 6
In order to adjust the terminal group concentration, monocarboxylic acid, dicarboxylic acid, monocarboxylic anhydride, dicarboxylic anhydride, monoamine, diamine, and the like may be added to the sixth resin.

If necessary, known viscosity stabilizers, light stabilizers, heat stabilizers, antistatic agents, dispersants, concealing agents and the like may be added as far as the object of the present invention is not impaired.

In the present invention, the relative degree of polymerization of the polyamide at a temperature of 25 ° C. of a 98% by weight sulfuric acid solution of 0.01 g / ml is preferably 2.2 to 6.0, particularly preferably 2.2 to 4.0. By setting the relative viscosity as described above, the manifestation of the mechanical properties becomes sufficient, and on the other hand, the melt viscosity does not become too high to make the melt spinning and melt molding difficult.

[0020]

The present invention will be described below in detail with reference to examples. The polymerization was carried out so that the relative viscosity was the same. Polymerization was performed three times under the same addition conditions, and the average and maximum values, the minimum value, and the difference between the maximum and minimum values of the amino terminal group amount of the obtained polymer were determined. <Relative viscosity> 0.01 g / ml using an Ostwald viscometer
Of a 98% by weight sulfuric acid solution / 25 ° C. was measured. <Measurement of amino terminal group amount>
The sample was dissolved in a mixed solvent of ethyl alcohol, and titrated with a hydrochloric acid solution using a potentiometric titrator to measure the amount of amino terminal groups in 1 g of the sample. <PH measurement> Using a HORIBA glass electrode as the electrode,
After diluting the mixed solution to 10% by weight, 30 ± 1 ℃
And the measurement was performed. Calibration of pH is pH 4, p
Calibration was performed using a standard solution of H7 and pH9.

2% by weight of isophthalic acid is added to a 50% by weight aqueous solution of adipic acid and hexamethylenediamine (hereinafter referred to as AH salt aqueous solution), and the pH of the 50% hexamethylenediamine aqueous solution becomes 7.4 to 7.5. Was added as above, and 0.15% by weight of 90% acetic acid with respect to the AH salt was added to the salt aqueous solution to carry out polymerization. Amino terminal group content and relative viscosity of the obtained polyamide resin and p of mixed salt aqueous solution
Table 1 also shows the measurement results of H.

[0022]

[Table 1] (Example 2) 2% by weight of terephthalic acid based on hexamethylene adipamide unit was added to and mixed with a 50% by weight aqueous solution of AH salt. Thereto, a 50% aqueous solution of hexamethylenediamine was added so that the pH of the mixed solution became 7.6 to 7.7, and 0.15% by weight of 90% acetic acid with respect to the AH salt was added to the aqueous salt solution to carry out polymerization. Example 3 1% by weight of isophthalic acid with respect to hexamethylene adipamide unit was added to and mixed with a 50% by weight aqueous solution of AH salt. Thereto, a 50% aqueous solution of hexamethylenediamine was added so that the pH of the mixed solution became 7.6 to 7.7, and 0.15% by weight of 90% acetic acid with respect to the AH salt was added to the aqueous salt solution to carry out polymerization. Comparative Example 1 Isophthalic acid of 2% by weight based on hexamethylene adipamide unit was added to and mixed with a 50% by weight aqueous solution of AH salt. Thereto, a 50% aqueous solution of hexamethylenediamine was added so that the pH of the mixed solution became 8.3 to 8.4, and 0.15% by weight of 90% acetic acid with respect to the AH salt was added to the aqueous salt solution to carry out polymerization. (Comparative Example 2) Water was added to the AH salt so as to be a 50% by weight aqueous solution, and 0.15% by weight of acetic acid was added to the AH salt, and 2% by weight of isophthalic acid was added to the hexamethylene adipamide unit. The polymerization is started by adding hexamethylene diamine to the dicarboxylic acid at a pressure of 5 × 10 ⁵ (Pa) during the pressurization after the start of the polymerization so that the dicarboxylic acid becomes theoretically equimolar without controlling the pH. To carry out polymerization. The results are shown in Table 1. As a result, in Examples 1 to 3, the CV value was smaller than in Comparative Examples 1 and 2, and it was confirmed that a polyamide resin having a stable amino terminal group amount was obtained.

[0023]

According to the analysis of the amount of amino terminal groups of the nylon 66 resin obtained by the polymerization, it was found that the amount of amino terminal groups was almost the same, and that the pH was out of the range indicated in the claims and the sample to which diamine was added after the polymerization was started. The variation in the amount of amino terminal groups is small.

Claims (3)

[Claims] 1. A dicarboxylic acid having a solubility of 1 g or less in 100 g of water at 15 ° C. is mixed with an aqueous solution of adipic acid and hexamethylenediamine, and the diamine and / or pH is adjusted so that the pH satisfies the formula (I). A method for producing a polyhexamethylene adipamide resin, comprising adding a dicarboxylic acid for use and polycondensing the mixed solution. 7.0 ≦ mixed solution pH ≦ 8.0 ・ ・ ・ (I) 2. The method for producing a polyhexamethylene adipamide resin according to claim 1, wherein the polymerization is carried out after concentration so that the concentration of the mixture becomes 80 to 95% by weight before polymerization. . 3. A molded article comprising a polyhexamethylene adipamide resin obtained by the method for producing a polyhexamethylene adipamide resin according to claim 1.