JPS6041647A - Preparation of oligomer - Google Patents

Abstract

PURPOSE:To obtain an oligomer useful for a nylon 12 polymer by the use of small-scale facilities in a short time, by carrying out hydrolyzing polymerization of lauryllactam continuously at extremely high temperature and high pressure. CONSTITUTION:Continuous hydrolyzing polymerization of lauryllactam is carried out in such a way that the relationship between heating temperature and added water content is in a range enclosed by lines obtained by connecting the points (370 deg.C, 2%), (340 deg.C, 3%), (325 deg.C, 10%), (310 deg.C, 20%), (300 deg.C, 30%), (295 deg.C, 50%), and (360 deg.C, 40%) shown by the figure, to give the desired substance. The added water content is weight % of water amount based on total weight of the whole polymerization system comprising lauryllactam, a copolymerizable monomer and an addition agent. A tubular container connected to a coil for a heat exchanger, and a heater is preferable as a continuous polymerizer.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing oligomers by continuous hydrolytic polymerization of lauryllactam.

Nylon 12 is produced from lauryl lactam by ring-opening polymerization, and in particular, when the polymer is produced industrially on a large scale, a hydrolysis polymerization method is used as the ring-opening polymerization method.

Hydrolytic polymerization of lauryllactam is a method of adding water to lauryllactam and raising the temperature to obtain nylon 12 oligomer. As is well known, in a subsequent step water is removed from this oligomer and it is converted into a condensation polymer to become nylon 12.

However, the hydrolysis polymerization rate of lauryl lactam is extremely slow, and is about 1710 to 1730 times the hydrolysis polymerization rate of caprolactam, which is a monomer of nylon 6. For this reason, high temperature and high pressure conditions are used, but the reaction time still takes a long time.

For example, the temperature is 280°C to 290°C, the amount of added moisture is 2 to 5 parts,
A reaction time of 5 to 15 hours is required at a pressure of 15 to 60 ume/crn2. For this reason, a patch polymerization method using an autoclave also requires large-scale high-pressure equipment, and a continuous polymerization method requires an even larger-scale and more complicated high-pressure equipment.

It is also estimated that the hydrolytic polymerization rate of lauryllactam will further increase by increasing the temperature and the amount of water added, but increasing the temperature and the amount of water added will increase the pressure during polymerization. Extremely, for example 100kq/c
It is estimated that the increase will be more than rn2. For this reason, it was considered that such conditions could not be achieved industrially due to the limits of the pressure resistance of the polymerization container, and instead attention had been focused on how to make polymerization possible under low pressure conditions.

An object of the present invention is to provide a method for producing an oligomer by continuously hydrolyzing and N-polymerizing lauryllactam in a short reaction time using small-scale equipment.

For this purpose, the present inventors changed their thinking and arrived at the present invention by carrying out the hydrolytic polymerization of lauryllactam under high temperature and high pressure conditions.In other words, the relationship between heating temperature and amount of water added On the graph with the heating temperature on the vertical axis and the amount of added moisture on the horizontal axis (370℃, 2nd section), (340℃, 3%
), (325℃, 10cm).

(310℃, 20 sections), (300℃, 30 sections), (29
5℃, 50 units).

It has been found that the object of the present invention can be achieved by continuously hydrolyzing and polymerizing lauryllactam within the range surrounded by the line connecting each point (360°C, 40 coefficient). Ta. That is, it has been found that when hydrolysis polymerization is carried out under such conditions, the reaction time can be shortened to within 30 minutes.

In batch polymerization, the monomer charging time.

This shortening of polymerization time may not be of great significance because the temperature rise time, product removal time, etc. are long, but in continuous polymerization, the residence time at high temperature and high pressure is 30 minutes.
Since the time can be reliably shortened to within minutes, the capacity of the high-temperature and high-pressure container used is reduced, and not only can the entire apparatus be downsized, but also a high-temperature and high-pressure container with a small volume f1 can be manufactured extremely easily. That is, the method of the present invention combines the hydrolytic polymerization of lauryllactam in an extremely short time under high temperature and high pressure, and the continuous polymerization method, which makes it extremely industrially efficient. Thus, there is provided a continuous method for producing lauryllactam oligomers which is advantageous for.

Specifically, the range of heating temperature and amount of added water used in the method of the present invention is the range shown in FIG. Here, the amount of water added refers to the amount of water relative to the weight of the entire polymerization system including lauryllactam, copolymerizable monomers, and additives. %
It is expressed as

If the temperature is lower than the range shown in FIG. 1, the polymerization rate will be slow; if the temperature is higher than the range shown in FIG. 1, problems such as coloring and formation of by-products will occur. Moreover, if the water content is less than the range shown in FIG. 1, the polymerization rate will be slow, whereas if it is too much, the pressure will become unnecessarily high, and the degree of polymerization of the obtained oligomer will be extremely reduced.

As the continuous polymerization device used to carry out the method of the present invention, it is preferable to use a tubular container connected to a heating device, such as a heat exchange coil, as shown in the examples below, and a high-pressure pump. lauryl lactam and water are fed into the tubular container through a heating device and polymerization takes place.

The gist of the present invention is to continuously polymerize lauryl lactam, which has a slow hydrolytic polymerization rate, using simple equipment, and the method according to the present invention uses not only lauryl lactam alone, but also lauryl lactam as a monomer component and a monomer that can be copolymerized therewith. A copolymer oligomer can be obtained by hydrolytic copolymerization. Furthermore, as long as the monomer is copolymerizable, it can be copolymerized not only with polyamide monomers but also with polyester monomers. For example, terpolymers of lauryllactam/caprolactam and adipic acid hexamethylene diamine salt useful as hot melt adhesives may also be suitably polymerized. Further, in addition to the monomer, additives such as a polymerization degree regulator, a polymerization accelerator, and a stabilizer can be added.

The nylon 12 oligomer or copolymerized oligomer obtained by the method of the present invention usually has a number average molecular weight Mn of 700 to 4.
000 under reduced pressure, normal pressure, or increased pressure to obtain high molecular weight nylon 12 or copolymer.

In this case, condensation conditions are such that the condensation is carried out at a temperature of 250 to 310°C for 20 minutes to 5 hours under a stream of nitrogen gas under normal pressure or reduced pressure. Continuous condensation is carried out by moving the suitably sized oligomer at a constant speed while stirring. Furthermore, the oligomers according to the invention can be used as raw materials for other polymers, such as by reacting with other compounds, for example polytetrahydrofuran.

The present invention will be described below with reference to Examples, but the present invention is not limited to these Examples.

Examples 1-4 The present invention was carried out using the apparatus shown in FIG.

In Figure 2, 1 has a heater 1a attached to its lower part at 200°C.
It is a silo heated to ℃ and contains lauryl lactam. This silo is filled with lauryllactam and then replaced with nitrogen, with a small amount of nitrogen constantly flowing to prevent air from entering the silo.

Lauryllactam is melted at the bottom of this silo.

The high-pressure pump 2 pumps a fixed amount into the flexible pipe 6.

The corrugated tube 6 is immersed in a night bath 7 that is kept at a constant temperature and stirred, and has an inner diameter of 10 mm and an outer diameter of 12 mm.
It is made of stainless steel and has a length of 30 mm.

6 is a silo with a steam pipe 3a at the bottom, and contains pure water in a boiling state. The boiling pure water is fed under constant pressure to a flexible pipe 5 in a night bath 7 by a high-pressure pump 4. Snake g5 has an inner diameter of 67 naφ.

It is made of stainless steel with an outer diameter of 8 mm and a length of 5 mm.

The pure water is heated through a corrugated tube 5 and then sent to a corrugated tube 6 where it is mixed with lauryllactam.

The mixture of lauryllactam and water, which has been heated in a corrugated pipe 6 and partially polymerized, is heated to a constant temperature by a band heater 8a from the outside, and has an inner diameter of about 50mm, an outer diameter of about 60mm, and a length of 5m. into a stainless steel reaction tube 8.

The reaction tube 8 has a total of 10 Mel blenders (static mixers) manufactured by Sulzer Co., Ltd. installed at intervals of about 50 Crn inside.
I have it.

The mixture of oligomer and water polymerized in the reaction tube 8 is flushed through a relief valve 9 that opens when the pressure reaches 150.7 or more and is sent to the cyclone 10. Cyclone 10
The heated steam is separated from the upper part and the molten oligomer is separated from the lower part, and the oligomer is cooled and solidified in the cooling water tank 11.

After drying, the solidified oligomer was subjected to Soxhlet extraction with acetone for 24 hours, and the amount of acetone extracted was measured. This corresponds to the amount of residual monomer.Moreover, the moisture content of the dried oligomer was measured at 250° C. using a coulometric titration moisture meter manufactured by Mitsubishi Kasei Corporation, and the approximate amount of condensed water was determined. The larger this value is, the lower the degree of polymerization of the oligomer is. The results are shown in Table-1.

The oligomer obtained in Example 1 was heated at 25% in a nitrogen stream.
After heating at 0° C. for 2.5 hours, a nylon 12 polymer was obtained. The obtained nylon 12 had good color and physical properties, and a degree of polymerization with a relative viscosity of 1.72 in a 0.5% m-cresol solution at 25°C.

Table-1

[Brief explanation of drawings]

FIG. 1 is a diagram showing the relationship between the heating temperature and the amount of added water in the present invention, and FIG. 2 is a schematic diagram of the apparatus used for carrying out the present invention. 1 is a silo, 2 is a high pressure pump, 3 is a hot water tank, 4 is a high pressure pump, 5 is a serpentine pipe, 6 is a serpentine pipe, 7 is a night pass, 8 is a reaction tube, 9 is a relief valve, 1o is a cycle pump, 11 is a cooling water tank

Claims (1)

[Claims] The relationship between the heating temperature and the amount of added water is shown in Figure 1 (370°C
, 2nd section) + (340℃ 13%), (325℃, 10chi)
. (310℃, -20cm), (300℃, 30cm), (2
95℃. Continuous hydrolytic polymerization or copolymerization of lauryllactam or a monomer that can be copolymerized with lauryllactam within the range surrounded by the helix connecting each point of 5ob) + (36o C, 4o%) A method for producing an oligomer, the method comprising: