JP3474028B2 - Method for producing high molecular weight nylon 6 - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a method for producing high-molecular-weight nylon 6 suitable as a material for high-strength and high-modulus materials. 2. Description of the Related Art High-strength, high-modulus materials have been actively studied, and high-strength, high-modulus fibers made of ultrahigh molecular weight polyethylene have already been industrialized. One factor that has made this possible with flexible polymers such as polyethylene is to increase the molecular weight of the polymer. In the production of nylon 6 by polymerization of ε-caprolactam, a water polymerization method, an anion polymerization method and the like are used. In the production of high molecular weight nylon 6 which is suitable as a material for high strength and high elastic modulus materials, Anionic polymerization is very advantageous compared to other polymerization methods. For example,
Abstracts of the 40th Meeting of Polymer Research Conference (Kobe), page 23 (1994) and Japanese Patent Publication No. 1-18077, describe a method for producing high molecular weight nylon 6 using an organic magnesium bromide compound as a basic catalyst. Is described. These methods remove water that can cause side reactions,
Additives increase the reactivity of the polymerization active species and relatively drive off side reactions to achieve higher molecular weight. In the anionic polymerization of ε-caprolactam using an acyllactam compound as an initiator,
If there is no side reaction, the molecular weight of the produced polymer is inversely proportional to the amount of the initiator. Therefore, if the amount of the initiator is reduced, the molecular weight can be increased without limit. However, for example, in the example of Japanese Patent Publication No. 1-19807, the amount of initiator is at least ε
-0.07 mol% with respect to caprolactam. As the amount of the initiator decreases, the polymerization rate decreases, and a new acyl group is formed from lactam and lactam anion as described in Comprehensive Polymer Science Vol. 3 (Pergamon Press, 1988, page 512) by Shevenda. The degree of contribution of the side reaction for producing lactam becomes relatively large. As described above, even if the amount of the acyllactam of the initiator is reduced, a new acyllactam is generated.Therefore, it is difficult to reduce the amount of the initiator and to increase the molecular weight with an initiator amount equal to or less than a certain value. . SUMMARY OF THE INVENTION The present invention relates to a method for producing nylon 6 by anionic polymerization of ε-caprolactam using an acyllactam compound as an initiator and an organic magnesium bromide compound as a basic catalyst. To provide a method for producing high-molecular-weight nylon 6 suitable as a high-strength and high-modulus material by suppressing the side reaction of The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that ε using an acyllactam compound as an initiator and an organic magnesium bromide compound as a basic catalyst. -In the anionic polymerization of caprolactam, by using an acyl lactam compound and an organic magnesium bromide compound in a specific amount, it has been found that side reactions can be suppressed without lowering the polymerization reactivity,
The present invention has been reached. That is, the present invention relates to the production of nylon 6 by anionic polymerization of ε-caprolactam using an acyllactam compound as an initiator and an organic magnesium bromide compound as a basic catalyst. 0.01-0.5 mol% used
The gist of the present invention is a method for producing nylon 6, wherein the amount of the organic magnesium bromide compound is 1.4 to 1.8 times the molar amount of the acyllactam group of the acyllactam compound. In the present invention, the acyllactam compound includes a compound which reacts with ε-caprolactam to produce an acyllactam compound, and the organic magnesium bromide compound includes an organic magnesium bromide compound and ε-caprolactam. And bromomagnesium lactamate. Hereinafter, the present invention will be described in detail. The ε-caprolactam used in the present invention needs to be substantially anhydrous. Specifically, the water content of ε-caprolactam must be 25 ppm or less. Examples of the method of removing water in ε-caprolactam include a method of flowing a dry inert gas such as dry nitrogen gas through ε-caprolactam in a molten state, and a method of recrystallization from cyclohexane or the like. The initiator in the present invention is a compound having one or two acyl lactam groups.
-Acetyl-ε-caprolactam, N-propionyl-
ε-caprolactam, N-benzoyl-ε-caprolactam, N, N′-adipoyl-bis-ε-caprolactam, N, N′-terephthaloyl-bis-ε-caprolactam and the like. In addition, the initiator reacts quickly with ε-caprolactam in the polymerization system to form an acyl lactam group of 1 to 1.
It may be a compound such as a carboxylic acid halide formed two times, and specific examples include caproyl chloride and adipoyl dichloride. The amount of the initiator used must be 0.01 to 0.5 mol% based on ε-caprolactam.
It is preferably 0.01 to 0.1 mol%. If the amount is less than this, the polymerization rate is extremely slow. Conversely, if the amount is more than this, high molecular weight nylon 6 cannot be obtained. The basic catalyst used in the present invention is an organic magnesium bromide compound, and specific examples thereof include ethyl magnesium bromide, isobutyl magnesium bromide,
Hexylmagnesium bromide, phenylmagnesium bromide, bromomagnesium isopropylcyclohexylamide and the like. These are all compounds which react quickly with ε-caprolactam in a polymerization system to produce bromomagnesium lactamate. Therefore, it is also preferable to separately prepare bromomagnesium lactamate to use as a basic catalyst. The amount of the basic catalyst used must be 1.4 to 1.8 times the molar amount of the acyllactam group of the initiator. The amount of the acyl lactam group is equimolar to the amount of the initiator having one acyl lactam group, and twice as much as the amount of the initiator having two acyl lactam groups. If the amount of the basic catalyst used is too small, the polymerization rate is slow. On the other hand, if the amount is too large, not only the effect of improving the polymerization rate is saturated, but also the reduction in molecular weight and the generation of a branched structure due to side reactions are not preferable. The polymerization temperature is from 100 to 200 ° C., especially from 145 to 17
Preferably, the temperature is 0 ° C. If the polymerization temperature is lower than 100 ° C., the polymerization does not proceed rapidly, while if it exceeds 200 ° C., a side reaction tends to occur. The polymerization atmosphere is preferably under an inert gas or under vacuum. Also, the ε of the initiator and the basic catalyst
-The order of addition to caprolactam may be arbitrary. Next, the present invention will be described specifically with reference to examples. The relative viscosity was measured with an Ubbelohde viscometer to 96.
The measurement was performed at a sample concentration of 1 g / dl and a temperature of 25 ° C. in% sulfuric acid. Example 1 To ε-caprolactam, 0.03 mol% of N-acetyl-ε-caprolactam based on ε-caprolactam as an initiator and ε-caprolactam as a basic catalyst
0.045 mol% of ethyl magnesium bromide (1.5 times mol of N-acetyl-ε-caprolactam) was added,
Anion polymerization was performed in a sealed tube at 150 ° C. for 12 hours under vacuum. The relative viscosity of nylon 6 obtained by hot water extraction of the product was 201.0. Comparative Example 1 Except that ethyl magnesium bromide was 0.02 mol% (0.67 times mol of N-acetyl-ε-caprolactam),
Polymerization was carried out in the same manner as in Example 1. The relative viscosity of nylon 6 obtained by hot water extraction of the product was 57.6. Comparative Example 2 Polymerization was carried out in the same manner as in Example 1 except that ethylmagnesium bromide was 0.5 mol% (17 times mol of N-acetyl-ε-caprolactam). The relative viscosity of nylon 6 obtained by hot water extraction of the product was 35.5. Example 2 0.05 mol% of N-acetyl-ε-caprolactam with respect to ε-caprolactam as an initiator and 0.1% with respect to ε-caprolactam as a basic catalyst.
08 mol% of ethyl magnesium bromide (1.6 times mol of N-acetyl-ε-acetylcaprolactam) was added, and anionic polymerization was carried out at 150 ° C. for 6 hours under vacuum in a sealed tube. The relative viscosity of nylon 6 obtained by hot water extraction of the product was 69.7. Comparative Example 3 Polymerization was carried out in the same manner as in Example 2 except that ethylmagnesium bromide was changed to 0.045 mol% (0.9 times mol of N-acetyl-ε-caprolactam). The relative viscosity of nylon 6 obtained by hot water extraction of the product was 31.7. Example 3 0.015 mol% of N, N'-adipoyl-bis-ε-caprolactam based on ε-caprolactam as initiator and 0.045 mol% based on ε-caprolactam as basic catalyst (1.5 times the amount of the acyllactam group of N, N'-adipoyl-bis-ε-caprolactam) was added thereto, and anionic polymerization was carried out at 150 ° C. for 12 hours under vacuum in a sealed tube.
The relative viscosity of nylon 6 obtained by hot water extraction of the product is
404.9. Comparative Example 4 Polymerization was carried out in the same manner as in Example 3 except that ethyl magnesium bromide was used in an amount of 0.5 mol% (17 times the amount of the acyllactam group). Nylon 6 obtained by hot water extraction of the product was insoluble in sulfuric acid, and the relative viscosity could not be measured. According to the present invention, in the anionic polymerization of ε-caprolactam using an acyllactam compound as an initiator and an organic magnesium bromide compound as a basic catalyst, side reactions can be suppressed, and high strength and high strength can be achieved. Nylon 6 having a high molecular weight suitable as a material of the elastic modulus material can be obtained.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C08G 69/00-69/50

Claims (1)

(57) [Claim 1] ε using an acyllactam compound as an initiator and an organic magnesium bromide compound as a basic catalyst
In the production of nylon 6 by anionic polymerization of caprolactam, an acyllactam compound is used in an amount of 0.01 to 0.5 mol% with respect to ε-caprolactam, and an organic magnesium bromide compound is used in an amount of 1.4 to 1.8 times the acyllactam group amount of the acyllactam compound. A method for producing high-molecular-weight nylon 6, characterized in that: