JPH05148358A - Ultrahigh molecular weight nylon 6 and its production - Google Patents

Abstract

PURPOSE:To obtain an ultrahigh molecular weight nylon 6 of a narrow molecular weight distribution by polymerizing anhydrous epsilon-caprolactam in the presence of a specified alkyllithium compound and a mono- or bis-acyl compound. CONSTITUTION:Anhydrous epsilon-caprolactam is polymerized in the presence of 0.1-2mol of 2-4C alkyllithium compound and 0.05-0.8mol of a mono- or bis- acyllactam at 100-200 deg.C to obtain the objective ultrahigh molecular weight nylon 6 of a relative viscosity (in 98% sulfuric acid in a concentration of 1g/dl at 30 deg.C) of 5-30 and a molecular weight distribution (in terms of a ratio of the weight-average molecular weight to the number-average molecular weight) of below 3.0.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to nylon 6 having a very high molecular weight and a narrow molecular weight distribution, which is suitable as a material for a material having a high strength and a high elastic modulus, and a process for producing the same.

[0002]

2. Description of the Related Art As a general method for producing a polyamide using a lactam as a raw material, there are a melt polymerization of a lactam using water as a catalyst, a combination of melt polymerization and solid phase polymerization, an anionic polymerization and the like. However, using the polyamides obtained by these polymerization methods, the strength and elastic modulus of fibers, films and the like obtained by ordinary molding and processing are at present 5 to 10 of theoretical strength and theoretical elastic modulus. Only about%. The first factor is that the molecular weight of polyamide is small.

For example, taking the synthesis of nylon 6 by the polymerization of ε-caprolactam as an example, the weight average molecular weight of nylon 6 obtained by the melt polymerization of ε-caprolactam with water as a catalyst is limited, and the maximum is 10 at most. It is about 10,000. Further, solid-state polymerization of nylon 6 obtained by melt polymerization increases the molecular weight but widens the molecular weight distribution. Therefore, for example, when a fiber is produced from such nylon 6, it cannot be uniformly stretched because it has a wide molecular weight distribution and sometimes exhibits multimodality, and thus a fiber having high strength and high elastic modulus is obtained. I can't. Furthermore, solid phase polymerization requires heat treatment for several tens of hours, so productivity is low,
There is a problem that the manufacturing cost becomes high.

On the other hand, anionic polymerization using an alkali metal such as sodium and potassium or a Grignard compound as a main catalyst gives a polymer having a higher molecular weight than that of nylon 6 obtained by melt polymerization or a combination of melt polymerization and solid phase polymerization. ..

For example, JP-B 34-10938 discloses that nylon 6 having a molecular weight of 50,000 or more is obtained by polymerizing ε-caprolactam in the presence of an alkali metal or alkaline earth metal catalyst and an acyllactam compound. However, the specific example of obtaining the ultra high molecular weight nylon 6 is not shown.

Further, Japanese Patent Publication No. 43-1621 discloses an anionic polymerization method of ε-caprolactam using an alkali metal and N-aluminum-ε-caprolactam as a catalyst. The weight average molecular weight of nylon 6 in the soluble range is at most about 250,000, which is not a satisfactory molecular weight level as a material for high-strength and high-modulus materials.

Further, Japanese Patent Publication No. 1-19807 discloses that nylon 6 having a weight average molecular weight of 30 to 100,000 was obtained by anionic polymerization of ε-caprolactam using a Grignard compound, an acyllactam compound and an organoaluminum compound. However, the organoaluminum compound used here is unstable, easily decomposes in the air, risk of ignition, and is expensive, so that it is not economical.

[0008]

DISCLOSURE OF THE INVENTION The present invention provides nylon 6 and ultrahigh molecular weight nylon 6 having an ultrahigh molecular weight and a narrow molecular weight distribution, which are suitable as materials for high strength and high elastic modulus materials, at relatively low temperature, and An object of the present invention is to provide a method for producing a good yield in a short time.

[0009]

The present invention is intended to solve the above-mentioned problems, and its gist is as follows. (1) 96% sulfuric acid as a solvent, a relative viscosity of 5 to 30 measured at a concentration of 1 g / dl and a temperature of 30 ° C., and a molecular weight distribution (ratio of weight average molecular weight to number average molecular weight) of less than 3.0. Ultra high molecular weight nylon 6. (2) Substantially anhydrous ε-caprolactam in the presence of 0.1 to 2 mol% of an alkyllithium compound having 2 to 4 carbon atoms and 0.05 to 0.8 mol% of a mono- or bisacyllactam compound (as an acyllactam group). A method for producing ultra-high molecular weight nylon 6 characterized by polymerizing at a temperature of 100 to 200 ° C.

The molecular weight distribution in the present invention is a value obtained by the following method. Wate with differential refractometer
By ALC / GPC150C gel permeation chromatography manufactured by rs, polystyrene was used as a standard sample, column temperature was 100 ° C., m-cresol was used as an eluent, flow rate was 0.4 ml / min, sample concentration was 0.1% by weight, and weight average was obtained. The molecular weight and the number average molecular weight are measured, and the ratio of the two is obtained.

The present invention will be described in detail below. Specific examples of the alkyllithium compound in the present invention include ethyllithium, n-propyllithium, i-propyllithium, n-butyllithium, sec-butyllithium, tert-butyllithium, and n-butyllithium, i. -Propyl lithium and sec-butyl lithium are preferably used.

The amount of alkyl lithium compound used is ε-
0.1 to 2 mol% relative to caprolactam, preferably 0.1
Must be ~ 1 mol%. If the amount used is less than 0.1 mol%, the polymerization rate will be slow, which is not preferable.

Examples of the monoacyllactam compound include acetylpropiolactam, acetylbutyrolactam, acetylvalerolactam, acetylcaprolactam, butyrylcaprolactam, benzoylcaprolactam and the like, and bisacyllactam compounds include, for example, adiacyllactam. Poilbisvalerolactam, adipoylbiscaprolactam, terephthaloylbiscaprolactam,
Examples include isophthaloyl biscaprolactam,
Representatives are acetylcaprolactam, adipoylbiscaprolactam and terephthaloylbiscaprolactam.

The amount of the acyllactam compound used is 0.05 mol as an acyllactam group based on ε-caprolactam.
It should be .about.0.8 mol%, preferably 0.1 to 0.5 mol%. (Since the bisacyllactam compound has two acyllactam groups in one molecule, it may be 1/2 of the amount of the monoacyllactam compound used.) When the amount of the mono- or bisacyllactam compound used is less than the above range The polymerization rate becomes slow, and the polymerization reaction does not occur quantitatively.
On the other hand, if the amount used exceeds the above range, satisfactory ultra high molecular weight nylon 6 cannot be obtained.

The polymerization temperature is 100 to 200 ° C., preferably 120.
It must be in the range of ~ 160. Polymerization temperature is 100 ℃
If it is less than this, the polymerization does not proceed rapidly, and the polymerization temperature is
When the temperature exceeds 200 ° C, a side reaction occurs and it is difficult to obtain solvent-soluble nylon 6.

As the polymerization pressure, any of normal pressure, increased pressure and reduced pressure can be applied, and the order of addition of the alkyllithium compound and the mono- or bisacyllactam compound to ε-caprolactam may be arbitrary.

In the present invention, a small amount (for example, 30 mol% or less) of another lactam component may be copolymerized as long as the polymerizability of ε-caprolactam and the physical properties of the produced nylon 6 are not impaired. Examples of copolymerizable lactams include α-pyrrolidone, α-piperidone, enanthlactam, capryllactam, laurolactam and the like.

[0018]

EXAMPLES Next, the present invention will be specifically described by way of examples.

Example 1 Epsilon-caprolactam 1 under atmospheric pressure and an oxygen-free dry nitrogen stream
Keep the moles at 80 ℃, N-acetylcaprolactam 0.001
And 0.003 mol of n-butyllithium (as a 15 wt% n-hexane solution). After distilling off n-hexane, the polymerization system was heated to 130 ° C. After 25 minutes, it became difficult to stir the polymerization system, and the polymerization was completed. The yield was 100%, the obtained nylon 6 was white, the relative viscosity was 23.6, and the molecular weight distribution was 2.60. Also, this nylon 6 is formic acid, m-
It was easily dissolved in cresol, sulfuric acid, etc. at room temperature.

Comparative Example 1 When the reaction was carried out under the same conditions as in Example 1 except that the amount of n-butyllithium added was 0.0006 mol, the polymerization hardly proceeded.

Comparative Example 2 The reaction was carried out under the same conditions as in Example 1 except that the amount of n-butyllithium added was 0.025 mol, and the polymerization was completed in 30 minutes. The yield was 100%, and the obtained nylon 6 was white and soluble in formic acid, m-cresol, sulfuric acid, etc., but the relative viscosity was low at 3.6.

Comparative Example 3 A reaction was conducted under the same conditions as in Example 1 except that the amount of N-acetylcaprolactam added was 0.0003 mol. As a result, white nylon 6 was obtained.
It took time, the yield was low at 30%, and the relative viscosity was low at 3.2.

Comparative Example 4 The reaction was carried out under the same conditions as in Example 1 except that the amount of N-acetylcaprolactam added was 0.01 mol.
The polymerization was completed in 5 minutes and the yield was 100%, but the obtained nylon 6 had a low relative viscosity of 2.4.

Examples 2 to 8 Reactions were carried out under the same conditions as in Example 1 except that the amounts of n-butyllithium and N-acetylcaprolactam added and the polymerization temperature were changed. The results are shown in Table 1.

[0025]

[Table 1]

In all cases, the yield was 100%, the obtained nylon 6 was white and easily dissolved in formic acid, m-cresol, sulfuric acid and the like at room temperature.

Example 9 ε-caprolactam 1 under normal pressure and oxygen-free dry nitrogen stream
0.001 mol of N-acetylcaprolactam and sec-butyllithium (as a 15% by weight cyclohexane solution) per mol.
005 moles were added. After distilling off cyclohexane, the polymerization system was heated to 140 ° C., and after 10 minutes, the polymerization was completed. The yield was 100%, the obtained nylon 6 was white, the relative viscosity was 21.2, and the molecular weight distribution was 2.23. The nylon 6 was easily dissolved in formic acid, m-cresol, sulfuric acid, etc. at room temperature.

Example 10 ε-caprolactam 1 under normal pressure and under a stream of dry oxygen-free nitrogen
0.001 mol of N-acetylcaprolactam and i-propyllithium (as a 15 wt% n-hexane solution) per mol.
005 moles were added. After n-hexane was distilled off, the polymerization system was heated to 140 ° C., and after 10 minutes, the polymerization was completed. The yield was 100%, the obtained nylon 6 was white, the relative viscosity was 18.4, and the molecular weight distribution was 2.27. The nylon 6 was easily dissolved in formic acid, m-cresol, sulfuric acid, etc. at room temperature.

Example 11 ε-caprolactam 1 under normal pressure and oxygen-free dry nitrogen stream
0.0005 mol of terephthaloylbiscaprolactam and 0.003 mol of n-butyllithium (as a 15 wt% n-hexane solution) were added to the mol. After n-hexane was distilled off, the polymerization system was heated to 130 ° C. After 25 minutes, the polymerization was completed. The yield was 100%, the obtained nylon 6 was white, the relative viscosity was 21.5, and the molecular weight distribution was 2.48. The nylon 6 was easily dissolved in formic acid, m-cresol, sulfuric acid, etc. at room temperature.

[0030]

According to the present invention, ultra high molecular weight nylon 6 having a relative viscosity of 5 to 30 can be produced in a high yield at a relatively low polymerization temperature and a short polymerization time. The nylon 6 obtained has an ultrahigh molecular weight, a narrow molecular weight distribution of less than 3.0, is very homogeneous, and is soluble in various solvents. It is suitably used as a material that gives a high-strength, high-modulus molded article by being highly oriented.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takaaki Matsuo 23 Uji Kozakura, Uji City, Kyoto Prefecture Unitika Ltd. Central Research Laboratory

Claims (2)

[Claims] 1. A 96% sulfuric acid as a solvent, a relative viscosity of 5 to 30 measured at a concentration of 1 g / dl and a temperature of 30 ° C., and a molecular weight distribution (ratio of weight average molecular weight to number average molecular weight) of less than 3.0. Ultra high molecular weight nylon 6. 2. A substantially anhydrous ε-caprolactam,
Alkyl lithium compounds having 2 to 4 carbon atoms 0.1 to 2 mol% and mono- or bisacyl lactam compounds 0.05 to 0.8
100% to 20% in the presence of mol% (as acyllactam group)
A process for producing ultra-high molecular weight nylon 6 characterized by polymerizing at a temperature of 0 ° C.