JPH0625257B2 - Method for producing high-viscosity crosslinked polyamide - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for producing a high-viscosity crosslinked polyamide, and more specifically, a specific amine having a primary amine at the terminal and a secondary amine in the main chain. The active polyfunctional carboxylic acid derivative is added to the polyamide (hereinafter, referred to as amine-modified polyamide) to react, and the main chain extension reaction by the terminal amine and the cross-linking reaction between the molecular chains by the secondary amine in the main chain simultaneously proceed. The present invention thus relates to a method for rapidly producing a high-viscosity crosslinked polyamide.

<Prior Art> Polyamides represented by nylon 6 and nylon 66 have been widely used in engineering plastics, films, fibers, etc. because they have excellent melt processability and mechanical properties. There is. In recent years, demands for various performance improvements such as tensile strength, impact resistance, dimensional stability, and wear resistance for these products have become stronger and stronger. In the field of plastics molding, especially extrusion molding of round bars, pipes, sheets, etc., and blow molding of large hollow containers, the above-mentioned physical properties as well as the shape retention of the melt are required, so high viscosity polyamide is required. Becomes

As a method for obtaining a high-viscosity polyamide, a method of performing melt polymerization for a long time under a nitrogen atmosphere or a vacuum, and a method of solid-phase polymerization using a catalyst such as a phosphorus compound are well known,
All of them require a long time for the reaction and have low productivity. Furthermore, the polyamides obtained by these methods have a drawback that they are easily hydrolyzed at the time of molding by a small amount of water contained in the pellets and become low-polymerization degree polymers.

As a method for improving the hydrolysis resistance, for example, Japanese Patent Publication Sho 62
JP-A-55532 proposes that a polyfunctional amine is added to a polyamide to cause polycondensation to cause a partial crosslinking (branching) reaction. According to this method, although the hydrolysis resistance is improved to some extent, it still takes a long time for the polymerization, and it is difficult to improve the quality due to the heat deterioration accompanying it. Furthermore, mechanical difficulty such as stirring, discharge and Problems such as the difficulty of pelletizing remain unsolved.

<Purpose of the Invention> An object of the present invention is to provide a polyamide having significantly improved hydrolysis resistance without concern about thermal deterioration during polymerization and without having to consider mechanical problems such as stirring during polymerization. To do.

<Structure of Invention> As a result of intensive investigations aimed at solving the above problems, the inventors of the present invention reacted a polyamide having a primary amine at the terminal and a secondary amine in the main chain with an active polyfunctional carboxylic acid derivative. When the reaction is carried out, not only the molecular chain is elongated by the reaction of the terminal amino group, but also the secondary amine in the main chain is involved in the reaction and intermolecular crosslinking is found to occur, and the present invention has been achieved. is there.

That is, according to the present invention, a polyalkylene polyamine represented by the following general formula (A) is copolymerized, has a primary amine at the terminal, and contains a secondary amine in the main chain, and melts in a substantially linear form. A method for producing a high-viscosity crosslinked polyamide, which comprises melt-reacting a possible polyamide with an active polyfunctional carboxylic acid derivative represented by the following general formula (a).

Formula _{(A) H 2 N [(} CH 2) m NH (CH 2) n NH] xH ( although, m, n is 2 to 12 a positive integer, and m =
n, or m ≠ n. X is an integer of 1 to 10) General formula (a) [Wherein A is an alkyl group or an aromatic group, and B is (R is an alkyl group), -O-Ar (Ar is an aromatic group), or a halogen atom,
n represents an integer of 2 or more] The amine-modified polyamide used in the present invention is not limited to the type of polyamide, but it is essential that it has a primary amine at the terminal and a secondary amine in the main chain at the same time. Becomes The types of polyamide include nylon 6, nylon 11, nylon 12, nylon 66, nylon 46, nylon 610, nylon 612, nylon MXD6 (polymeta-xylylene adipamide, nylon 6/66 copolymer, nylon 6 / 6T There is no particular limitation as long as it is a substantially linear and meltable polyamide such as a polymer, a nylon 66 / 6T copolymer, a nylon 66 / 6T / 6I copolymer, or a nylon 6T / 6I copolymer.

Polyamides usually have an amino group (primary amine) and a carboxyl group at the terminal, but in order to obtain an amine-modified polyamide having a secondary amine in the main chain, which is an essential condition in the present invention, the general formula (A) ... H ₂ N [(CH ₂ ) mNH (CH ₂ ) nNH] xH (however,
m and n are positive integers of 2 to 12, and m = n or m ≠ n. Further, a polyalkylene polyamine represented by the formula (x is an integer of 1 to 10) is added to the polyamide polycondensation reaction to bond (copolymerize) to the polyamide molecular chain. Specific examples of the polyalkylene polyamine include diethylene triamine triethylene tetramine tetraethylene pentamine pentaethylene hexamine hexaethylene heptamine heptaethylene octamine bis (trimethylene) triamine (trimethylene) tetramine diethylene (hexamethylene)
Tetramine diethylene (dihexamethylene) pentamine triethylene-bis (hexamethylene) hexamine diethylene (decamethylene) tetramine and the like. Among these, the polyethylene polyamine compounds indicated by are commercially available as industrial chemicals and can be used particularly advantageously.

These polyalkylene polyamines each have a primary amine at both ends of the linear molecule and several secondary amines in the molecule, and when added to the polycondensation reaction system, the primary amine at the end will react with the carboxyl group. Although involved, the reactivity of the secondary amine is low and it does not react with the carboxyl group at normal polymerization temperature. Therefore, it is possible to obtain a substantially linear, meltable polyamide having a secondary amine in the main chain used in the present invention. By the way, in the present invention, the presence of a primary amine (terminal amino group) is required at the terminal of the polyamide in order to extend the polyamide molecular chain conductor by the reaction of the terminal amino group and the active polyfunctional carboxylic acid derivative. Of course, the polyamide has a terminal amino group and a terminal carboxyl group, but the polyamide used in the present invention preferably has more terminal amino groups than the terminal carboxyl groups. The addition of the polyalkylene polyamine not only introduces a secondary amine into the main chain but also satisfies the above requirements at the same time.

The polyalkylene amine may be used alone or in combination with a dicarboxylic acid such as adipic acid or sebacic acid. When used alone, it cannot be added in a very large amount in view of the obtained molecular weight, but it is not particularly limited when used in combination with a dicarboxylic acid. At this time, it is preferable that the molar ratio of the polyalkylene polyamine to the dicarboxylic acid is 1.0 or more, and the amount of terminal amino groups of the obtained polyamide is larger than that of terminal carboxyl groups.

Thus, the combined use of dicarboxylic acid and polyalkylene polyamine makes it possible to independently control the amount of secondary amine and the amount of terminal amino group in the main chain by adjusting the addition amount and the addition molar ratio. By controlling the reaction with the derivative, it becomes possible to control the physical properties of the finally obtained polyamide.

When the polyalkylene polyamine is used alone, the addition amount is 0.05 to 2.0 mol% with respect to the monomer, preferably
It is 0.10 to 1.0 mol%.

If it is less than 0.05 mol%, the effect of increasing the viscosity is small, and if it exceeds 2.0 mol%, the base polyamide has a low molecular weight and is difficult to handle such as pelletization, which is not preferable. On the other hand, when used in combination with a dicarboxylic acid, the addition amount of the polyalkylene polyamine is not particularly limited, but if added too much, the physical properties in terms of heat resistance decrease, so 0.05 to 5.0
It is desirable to keep it in the range of mol%.

The active polyfunctional carboxylic acid derivative used in the present invention is represented by the following general formula (a), and can be roughly classified into three types according to the type of B in the formula.

(a) (A in the formula represents an alkyl group or an aromatic group, and n represents an integer of 2 or more) Type I (a) (R is an alkyl group) Type II B = -O-Ar in the formula (a) (Ar is an aromatic group) Type III B = halogen atom in the formula (a) Type I is a so-called polyfunctional N-acyl lactam, type
II is a polyfunctional aromatic ester, and type III is a polyfunctional acyl halide, both of which are active carboxylic acid derivatives having enhanced reactivity and easily react with not only primary amines but also secondary amines.

Specific examples of the polyfunctional N-acyl lactam of type I include N, N′-terephthaloylbis-ε-caprolactam,
N, N′-isophthaloylbis-ε-caprolactam,
N, N'-succinylbis-ε-caprolactam, N,
N′-glutarylbis-ε-caprolactam, N, N ′
-Adipoylbis-ε-caprolactam, N, N'-sebacylbis-ε-caprolactam, N, N'-adipoylbis-ε-valerolactam, N, N'-terephthaloylbisvalerolactam, N, N'-terephthalloy Rubisbutyrolactam, N, N'-isophthaloylbisvalerolactam, N, N'-isophthaloylbisbutyrolactam and other bifunctional N-acyllactams, and further N, N ', N "
-Trimezoyl tris-ε-caprolactam, N,
N ', N "-trimezoyl trisvalerolactam, N,
N ', N "-trimezoyl trisbutyrolactam, 1,4,
5,8-naphthalene tetracarboxylic acid tetra-ε-caprolactam, cyclohexanone tetrapropionic acid tetra-ε-caprolactam, dicyclohexanone octapropionic acid tetra-ε-caprolactam, polyacrylic acid poly-ε-caprolactam, etc. Mention may be made of acyllactams. These polyfunctional N-acyl lactams can be easily synthesized by reacting the corresponding carboxylic acid halide and lactam in the presence of a tertiary amine or an inorganic alkali such as NaOH or KOH.

Specific examples of the type II polyfunctional aromatic ester include terephthalic acid diphenyl ester, isophthalic acid diphenyl ester, succinic acid diphenyl ester, adipic acid diphenyl ester, pimelic acid diphenyl ester,
Suberic acid diphenyl ester, azelaic acid diphenyl ester, sebacic acid diphenyl ester, trimesic acid triphenyl ester, 1,2,4-benzenetricarboxylic acid triphenyl ester, terephthalic acid bis (p-
Examples thereof include nitrophenyl ester, terephthalic acid bis (p-chlorophenyl) ester, and naphthalene-1,5-dicarboxylic acid diphenyl ester.

Specific examples of the type III polyfunctional acyl halides include:
Terephthalic acid dichloride, terephthalic acid dibromide, isophthalic acid dichloride, isophthalic acid dibromide, trimesic acid trichloride, trimesic acid tribromide, 1,2,4-benzenetricarboxylic acid trichloride, succinic acid dichloride, adipic acid dichloride, etc. To be

The above-mentioned three types of active polyfunctional carboxylic acid derivatives react with amines to form amide bonds, and when type I is used as a by-product, lactams, type II are phenols, and type II are used. III produces hydrogen halide. Phenols and hydrogen halides are somewhat odorous and corrosive, so that their use is somewhat limited depending on the intended use of the final polyamide. Type I does not have these concerns at all, and lactams have a high affinity with polyamides, and are therefore particularly advantageously used in the present invention.

In reacting the active polyfunctional carboxylic acid derivative with the amine-modified polyamide, an active polyfunctional carboxylic acid derivative is added during or after the polymerization of the polyamide,
A method of mixing and stirring in a polymerization reactor, or a method of reacting in a melt kneader (extruder) at the time of blow molding, injection molding, extrusion molding of plastic, and molding of final products such as yarn forming and film forming is adopted. It The former method of reacting in a polymerization reactor has a limitation that it is difficult to make a very viscous one because of stirring and discharge cutting.
Therefore, in the present invention, the latter method of reacting at the time of molding is particularly advantageously adopted.

To react in an extruder, a method in which an amine-modified polyamide chip and an active polyfunctional carboxylic acid derivative are blended in advance and then supplied, or a high-concentration master chip of the active polyfunctional carboxylic acid derivative is added to the polyamide chip and blended Or a method in which a solution of the active polyfunctional carboxylic acid derivative (itself when the agent is a liquid) is metered in at the entrance of the extruder or in the middle is convenient.

The type of the active polyfunctional carboxylic acid derivative is arbitrarily selected according to the moldability and the physical properties of the final product. Generally, a compound having three or more functional groups is used to particularly increase the degree of crosslinking, and a compound having a particularly long molecular chain is used. A bifunctional compound is selected. In either case, crosslinking and molecular chain extension proceed simultaneously. Further, it is of course possible to use a bifunctional compound and a trifunctional or higher functional compound together.

The addition amount of these polyfunctional carboxylic acids is
It is arbitrarily selected within the range of 0.1 to 10.0% by weight. If the amount is less than 0.1% by weight, the effect of the present invention is not remarkable,
If it exceeds 10.0% by weight, no further effect can be expected. A particularly preferable addition amount range is 0.3 to 5.0% by weight.

The reaction conditions are such that the temperature is higher than the melting point of the polyamide by 5 to 150 ° C., preferably 20 to 80 ° C., for 0.5 to 20 minutes, preferably 1 to 6 minutes.

<Effects of the Invention> According to the present invention, pellets, fibers, films, and other injection-molded products, blow-molded products, extrusion-molded products, and compression-molded products of high-viscosity crosslinked polyamide, which have been difficult in the past, can be easily obtained. It is possible to improve the performance of molded products and to bring out new physical properties.

It is known in JP-B-57-53169 that a polyamide and a N, N 'bisacyl lactam are reacted in a molten state to increase the viscosity of the polyamide. There is no disclosure of modified polyamides.

Examples will be described below, but the present invention is not limited thereto.

In the examples, [η] was determined by dissolving the sample in m-cresol at 35 ° C. Terminal amine [NH ₂ ] and secondary amine [NH] dissolve the sample in m-cresol and
The total amount of [NH ₂ ] and [NH] was obtained by titrating with 01N p-toluenesulfonic acid, and each value was calculated. The terminal carboxyl group [COOH] is
Dissolve the sample in benzyl alcohol and add 0.1N Na.
It was determined by titration with OH. Melt viscosity is 1mm hole diameter, 10mm hole length
Using Shimadzu's high-performance flow tester with the nozzle set, the melting temperature is 270 ℃ and the shear rate is 100se.
It was measured at c ^-1 .

Note that, as is clear from the above description, the present application includes the following aspects.

(a) The polyamide is an aliphatic polyamide, or one or both of a diamine component or a dicarboxylic acid component is an aromatic component, and is substantially linear and meltable.

(b) The modified polyamide is a polyamide obtained by copolymerizing the polyamide of the above item (a) with a polyalkylene polyamine represented by the following formula.

_{H 2 N [(CH 2)} mNH (CH 2) NH] xH (c) that the copolymerization ratio of the polyalkylene polyamine (to monomer ratio) is 0.05 to 2.0 mol%.

(d) The modified polyamide is obtained by copolymerizing the polyamide of the above item (a) with a polyalkylene polyamine represented by the following formula in combination with a dicarboxylic acid.

_{H 2 N [(CH 2)} mNH (CH 2) NH] xH (e) the molar ratio dicarboxylic acid polyalkylene polyamine is 1.0 or more.

(f) The active polyfunctional carboxylic acid is a polyfunctional N-acyl lactam, a polyfunctional aromatic ester, or a polyfunctional acyl halide.

(g) The amount of the active polyfunctional carboxylic acid added to the modified polyamide is 0.1 to 10.0% by weight.

(h) The melting reaction condition is a temperature of 5 to 150 higher than the melting point of polyamide and 0.5 to 20 minutes.

Example 1 250 parts of ε-caprolactam (ε-CL) and 0.60 part of diethylenetriamine (0.26 mol% relative to ε-CL) were charged into an autoclave, and after a stirring reaction at a steam pressure of 3.5 kg / cm ² and a temperature of 255 ° C. for 3 hours, The pressure was returned to normal pressure to obtain an initial polycondensate. Subsequently, polycondensation reaction was carried out for 3 hours and 15 minutes while flowing nitrogen, and then discharged, cut, washed with hot water, and dried at high temperature nitrogen to obtain a water content of 0.03%, [η] 1.1.
7, base amine of terminal primary amine [NH ₂ ] 80 gram equivalent / 10 ⁶ g, secondary amine [NH] 26 gram equivalent / 10 ⁶ g, terminal carboxyl group [COOH] 28 gram equivalent / 10 ⁶ g was obtained. .

This base chip was blended with N, N′-terephthaloylbis-ε-caprolactam as an active polyfunctional carboxylic acid derivative, melt-kneaded in a biaxial ruder at 260 ° C. for 3 minutes, then extruded and cut, A highly viscous crosslinked polymer was obtained. The melt viscosity of this polymer and the solubility in m-cresol (which is closely related to the degree of crosslinking) are shown in Table 1.

Examples 2 to 5 and Comparative Example 1 Table 1 shows the results of the test conducted in Example 1 by changing the type and the addition amount of the active polyfunctional carboxylic acid derivative.

Comparative Example 2 250 parts of ε-caprolactam and m-xylylenediamine
1.0 part (0.34 mol% vs. ε-CL) was charged into an autoclave and the same operation as in Example 1 was performed to obtain a water content of 0.03.
%, [Η] 1.17, terminal primary amine [NH ₂ ] 85 gram equivalent / 10 ⁶ g, primary amine [NH] 0 gram equivalent / 10 ⁶ g,
A base chip having 20 gram equivalents of terminal carboxyl groups / 10 ⁶ g was obtained. In addition, N, N'-terephthaloylbis-ε-
The amount of caprolactam shown in Table 1 was added, and the mixture was passed through a biaxial ruder under the same conditions as in Example 1. Although the melt viscosity of the obtained polymer was high, it was confirmed that the polymer was completely dissolved in m-cresol and that crosslinking did not occur.

Examples 6, 7 ε-caprolactam 250 parts, diethylenetriamine 0.96
Parts (0.42 mol% vs. ε-CL) and adipic acid 0.68 parts (0.2
1 mol vs. ε-CL) was charged into an autoclave and Example 1
By performing the same operation as above, the water content is 0.04%, [η] 1.
13, terminal primary amine [NH ₂ ] 82 gram equivalent / 10 ⁶ g,
A base chip having a secondary amine [NH] of 43 gram equivalent / 10 ⁶ g and a terminal carboxyl group [COOH] of 39 gram equivalent / 10 ⁶ g was obtained. The active polyfunctional carboxylic acid derivative shown in Table 2 was blended with this base chip and passed through a biaxial ruder under the same conditions as in Example 1, and as a result, the highly viscous crosslinked polymer shown in Table 2 was obtained.

Example 8 250 parts of ε-caprolactam, 0.7 of triethylenetetramine
2 parts (0.25 mol% vs. ε-CL) were charged into an autoclave and the same operation as in Example 1 was performed to obtain a water content of 0.03.
%, [Η] 1.19, terminal primary amine [NH ₂ ] 72 gram equivalent / 10 ⁶ g, secondary amine [NH] 44 gram equivalent / 10 ⁶ g,
Terminal carboxyl group equivalent [COOH] 28 grams equivalent / 10
⁶ g of base chip was obtained. N on this base chip
1.8 'N-terephthaloylbis-ε-caprolactam
The mixture was blended by adding t%, passed through a biaxial ruder under the same conditions as in Example 1, and cut to obtain pellets. The melt viscosity of these pellets was 108,300 poise and it was partially insoluble in m-cresol.

Example 9 ε-caprolactam 250 parts, diethylenetriamine 2.1 parts (0.92 mol% vs ε-CL) and adipic acid 2.2 parts (0.68 mo)
1% to ε-CL) was charged in an autoclave, and Example 1 was used.
By performing the same operation as above, the water content is 0.02%, [η] 1.
20, terminal primary amine [NH ₂ ] 83 g equivalent / 10 ⁶ g,
A base chip of secondary amine [NH] 92 gram equivalent / 10 ⁶ g was obtained. 2.5 wt% of N, N′-terephthaloylbis-ε-caprolactam was added to this base chip and blended, and the mixture was cut through a biaxial ruder under the same conditions as in Example 1 and cut to obtain pellets. The melt viscosity of this pellet is
It was insoluble in m-cresol at 45,000 poise.

Example 10 and Comparative Example 3 1.5 wt% of N, N'-terephthaloylbis-ε-caprolactam was added to the base chip obtained in Example 1 and blended, and the blended product was fed to an extrusion molding machine to a resin temperature of 265 ° C. Diameter 55m
A round bar of m was formed. The machinability and physical property evaluation results of this round bar are shown in Table 3.

For comparison (Comparative Example 3), [η] 1.85 obtained by polycondensation of ε-caprolactam alone, primary amine at the terminal [N]
H ₂ ] 32 gram equivalent / 10 ⁶ g, terminal carboxyl group 34 gram equivalent / 10 ⁶ g, and a nylon 6 chip having a moisture content of 0.08% were similarly extruded to form a round bar, and the evaluation results are also shown.

As is clear from Table 3, when the polymer of the present invention is used, the heat distortion temperature, bending strength and bending elastic modulus are greatly improved. Further, it has been found that it is possible to perform internal thread cutting without oil, and the workability is significantly improved.

The data of Examples 1 to 10 are summarized as follows.

Claims (1)

[Claims] 1. A polyalkylene polyamine represented by the following general formula (A) is copolymerized, has a primary amine at the terminal and contains a secondary amine in the main chain, and is meltable in a substantially linear form. A method for producing a high-viscosity crosslinked polyamide, characterized in that the polyamide is melt-reacted with an active polyfunctional carboxylic acid derivative represented by the following general formula (a). Formula _{(A) ... H 2 N [} (CH 2) m NH (CH 2) n NH] xH ( although, m, n is a positive integer of 2-12, and m =
n, or m ≠ n. X represents an integer of 1 to 10) General formula (a) ... [Wherein A is an alkyl group or an aromatic group, and B is (R is an alkyl group), -O-Ar (Ar is an aromatic group), or a halogen atom,
n represents an integer of 2 or more]