JPH02153936A - Production of polymer - Google Patents

Abstract

PURPOSE:To stably produce a polymer having a desired molecular weight by carrying out polymerization reaction while measuring heat transfer characteristic values of a reaction solution in melt polymerization and completing the polymerization reaction when the value attains a prescribed value. CONSTITUTION:A polymer, such as polyester or polyamide, is produced by a melt polymerization method. In the process, the polymerization reaction is carried out while measuring heat transfer characteristic values of a reaction solution. When the heat transfer characteristic values attain a prescribed value, the polymerization reaction is completed to afford a polyester having, e.g. 500-8,000 molecular weight. Furthermore, the heat transfer characteristic values are measured by a method for, e.g. inserting two sensing elements (A) and (B) into the reaction solution, measuring the temperature (TA) of the reactants with an ordinary temperature sensor, on the other hand, measuring the temperature (TB) of the sensing element (B) capable of flowing a current of an optional value therethrough when Joule's heat generated by electric conduction thereof is included and taking the difference (DELTAT) between (TA) and (TB) as the heat transfer characteristic values.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing a polymer in which the end point of a reaction is determined using heat transfer characteristic values of nine reactants as an index.

(Prior art) When producing a polymer, it is necessary to terminate the reaction when a predetermined molecular weight is reached. Conventionally, methods for determining the end point of a single polymerization reaction include the wattmeter method and the time-lapse sampling method. It has been adopted.

The wattmeter method takes advantage of the fact that the rotational torque of the stirrer increases as the viscosity of the reactant increases, and the time-lapse sampling method collects samples from the reactant at appropriate times during the polymerization reaction to determine the molecular weight, etc. of the sample. This method determines the end point of one reaction by measuring off-line.

A process viscometer that utilizes pressure loss, a one-turn condensation meter, a thin tube viscometer, etc. is installed in the low 2 reactor or in the piping attached to the reactor, and the end point of the reaction is determined based on the instructions from the viscometer. Methods for making the determination are also known.

(Problems to be Solved by the Invention) However, although the wattmeter method is somewhat effective in producing high molecular weight polymers, its accuracy is insufficient. In particular, when producing low molecular weight polymers, the change in the rotational torque of the stirrer between the start and end of 8 reactions is small, making it difficult to determine the end point of 1 reaction, and it is difficult to stabilize a polymer with a constant molecular weight. could not be manufactured.

On the other hand, in the time-lapse sample collection method, it takes a considerable amount of time to measure the molecular weight of the collected sample, so it is difficult to keep the molecular weight of the reactant in one reactor constant until a 9 judgment result is obtained. There is.

Furthermore, even if it could be maintained, the operability would be poor and there would be many practical problems in any case. In particular, when producing relatively low molecular weight polymers, this method is not practical because the molecular weight of the reactant often changes significantly during the time required to measure the sample.

Further, the method using a 9-rotation viscometer or a thin cylindrical viscosity needle is more suitable for producing low molecular weight polymers than the above three methods, but is insufficient in terms of accuracy and/or precision.

The present invention improves these problems and enables stable production of a polymer of a desired molecular weight repeatedly when producing a 9-polymer, even when producing a polymer of any molecular weight, especially a low molecular weight polymer. This is an attempt to provide a possible method.

(Means for Solving the Problem) The present inventors have discovered that the heat transfer characteristic value of the zero reactant changes in response to changes in the melt viscosity of the reactant, and uses this to determine the end point of the polymerization reaction. By doing so, we succeeded in solving the above issues.

We have arrived at the present invention.

That is, 1. When producing a polymer by a melt polymerization method, the polymerization reaction is carried out while measuring the heat transfer characteristic value of the reaction liquid, and the polymerization reaction is terminated when the heat transfer characteristic value reaches a predetermined value. The gist of the present invention is a method for producing a polymer characterized by the following.

The polymer to which the method of the present invention is applied can basically be of any type as long as it can be obtained by melt polymerization, and specifically includes polyester, polyamide, and polyacrylic polymers. Coalescence, polyvinyl polymer, epoxy polymer.

Examples include urethane polymers.

Hereinafter, the present invention will be explained by taking as an example polyester, which has a wide range of uses regardless of whether it has a low molecular weight or a high molecular weight.

Polyesters are terephthalic acid and isophthalic acid.

2. A polyhydric carboxylic acid component such as 6-naphthalene dicarboxylic acid, adipic acid, trimellitic acid, and ester-forming derivatives thereof, and ethylene glycol.

Butanediol, neopentyl glycol, 1,4-cyclohexane dimetatool, trimethylolpropane,
Polyhydric alcohol components such as glycerin, pentaerythritol and their ester-forming derivatives and/or p-
It is produced from hydroxycarboxylic acid components such as hydroxybenzoic acid and its ester-forming derivatives.

Polyester is usually produced by a method in which oligomers are produced by esterification or transesterification and then polycondensed, but in the present invention, the polycondensation reaction is carried out while measuring the heat transfer property values of the reaction liquid. The reaction is terminated when the heat transfer characteristic value reaches a value corresponding to the desired molecular weight.

A typical method for measuring heat transfer characteristic values is as follows.

Insert two detection ends; detection ends A and B into the reaction solution.

The detection end A is a normal temperature detection end and measures the temperature TA of the reactant. On the other hand, the detection end B is designed to allow a current of an arbitrary value to flow therethrough, and measures the temperature T of the detection end B when taking into account the Joule heat generated by the current flow.

In the present invention, the difference (ΔT) between l Tl and TA is taken as a heat transfer characteristic value, and is used as an index of the viscosity of the reactant. That is, since the ΔT value increases as the melt viscosity of the reactant increases, relative changes in melt viscosity can be monitored with high accuracy.

Furthermore, the present invention may be implemented by a method of controlling the current value of the detection end B necessary to maintain a certain constant ΔT value.

In this case, as the viscosity of one reactant increases, the current value decreases.

The molecular weight of the polymer produced by the method of the present invention is not particularly limited, but in general, from the viewpoint of ease of discharging the polymer from the three reactors after the completion of one reaction, the molecular weight of the polymer is usually 500 to so, o.
It is about oo. In particular, it has been difficult to stably produce polyester with a low molecular weight of about 500 to 8,000 using conventional techniques.

It is advantageous to apply the method of the invention.

The relationship between the molecular weight of the polymer and the heat transfer characteristic value (ΔT) varies depending on the type of polymer, the reaction temperature, the flow state of the reaction liquid, the current value when energizing the detection end B, etc. If we obtain the above relationship while keeping constant, then Δτ
By measuring the value, it becomes possible to stably produce a polymer with the desired molecular weight.

(for production) The present invention is believed to be based on the following principles.

- Since the polymerization reaction is carried out while stirring the reactants when fishing on a boat, the reactants are always in flux. When a constant current is passed through detection end B to generate heat 9 If the reactant has a low viscosity (low molecular weight), convective heat transfer is large.

The amount of heat removed from the surface of the detection end B by heat radiation increases, and the ΔT becomes smaller.

On the other hand, if 1 reactant has a high viscosity (high molecular weight),
The amount of heat taken away from the detection end B becomes relatively smaller than when the reactant has a low viscosity. therefore.

If other conditions are constant, the ΔT becomes large.

Other conditions 9 For example, it is possible to control the stirring conditions in the reactor and the reaction temperature T^ to a constant value, so ΔT-TI
The viscosity of one reactant can be determined by measuring -'ra. In other words.

8T increases as the viscosity of the reactants increases (molecular weight increases).

(Example) Hereinafter, the present invention will be explained in more detail with reference to Examples.

In addition, in the case of polyester, the relative viscosity ηr in the examples is 2
In the case of polyamide, it is a value measured at 25°C in 96% concentrated sulfuric acid. Moreover, 9 molecular weight is the number average molecular weight determined by the terminal group determination method.

Incidentally, the amount of Ifi groups in each powder was determined by the following method.

polyester The amount of carboxyl end groups is dissolved in dioxane.

It was determined by titration with a potassium hydroxide-methanol solution.

The amount of hydroxyl end groups is dissolved in pyridine.

After acetylation, it was determined by titration with a potassium hydroxide-methanol solution.

The amount of polyamide carboxyl terminal groups was determined by dissolving the polyamide in benzyl alcohol and titrating with a potassium hydroxide-benzyl alcohol solution.

The amount of amino terminal groups was dissolved in 1 m-cresol.

p-) It was determined by titration with an aqueous solution of luenesulfonic acid.

In addition, regarding the data processing device including the detection end for measuring the heat transfer characteristic value ΔT, the kinematic viscosity monitoring system V? made by JEOL ■ is available. ! -4000 was used.

Example 1 70 moles of terephthalic acid, 30 moles of isophthalic acid, 50 moles of ethylene glycol and 11 moles of neopentyl glycol
0 mol was charged into a reactor, and an esterification reaction was carried out at 260° C. under a controlled pressure of 3.0 kg/ant. Detection end A for measuring heat transfer characteristic value ΔT after completion of esterification reaction
and B into the reaction solution, and the current value at the detection end B was set to 0.3.
While measuring ΔT as amperes.

The polycondensation reaction was carried out under reduced pressure of 0.5 Torr for the time (unit: minutes) shown in Table 1.

Table 1 shows the ΔT, the molecular weight of the polyester, and ηr at each polycondensation reaction time.

Table 1 Based on these results, the relationship between the double condensation reaction time and ΔT and ηr is shown in a graph as shown in FIG.

Example 2 Under the conditions of Example 1 (polycondensation reaction time approximately 90 minutes).

Polyester production was carried out five times. However, regardless of the reaction time, the reaction was terminated when ΔT reached 29.29°C.

Table 2 shows the results of measuring the molecular weight and ηr of the obtained polyester.

The molecular weight of the polyamide in Table 2 is 6840. ηr is 1.299
I sang.

Example 4 Polyamide was produced seven times under the conditions of Example 3. However, regardless of the reaction time, the reaction was terminated when ΔT reached 18.32°C. Table 3 shows the results of measuring the molecular weight and ηr of the obtained polyamide.

Table 3 Example 3 100 moles of ε-caprolactam and 5 moles of ε-aminocaproic acid were charged into a reactor, and after reacting at 150°C for 30 minutes under normal pressure, the temperature was raised to 260°C. After increasing the temperature, detecting ends A and B for measuring ΔT were inserted into the reaction solution, and the current value of the detecting end B was set to 0.25 ampere, and the polymerization reaction was carried out for 45 minutes under a reduced pressure of 0.5 ml. Ta.

The Δτ value at this time was 18.32°C. (Effects of the Invention) According to the present invention, it is possible to accurately determine the end point of a single polymerization reaction, and to stabilize a polymer with a desired molecular weight. This makes it possible to manufacture

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between the polycondensation reaction time and ΔT and ηr obtained in Example 1.

Claims (3)

[Claims] (1) When producing a polymer by the melt polymerization method, the polymerization reaction is carried out while measuring the heat transfer characteristic value of the reaction solution, and the polymerization reaction is terminated when the heat transfer characteristic value reaches a predetermined value. A method for producing characteristic polymers. (2) The method according to claim 1, wherein the polymer is polyester or polyamide. (3) The method according to claim 1, wherein a polyester having a molecular weight of 500 to 8,000 is produced.