JPH0327572B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a novel continuous polymerization method of polyparaphenylene terephthalamide and an innovative low-temperature delay system that can be carried out on an industrial scale. So-called aromatic polyamides, in which aromatic groups are linked with amide bonds, are used for fibers, etc. due to their excellent heat resistance.
It is useful as films, fibrids, etc. Among them, polyparaphenylene terephthalamide, which consists of repeating units in which an amide group is bonded to the para position of an aromatic ring, is extremely useful because it exhibits particularly excellent heat resistance and mechanical properties. , and its uses are being developed one after another. [Prior Art] Generally, aromatic polyamides are produced by low-temperature polycondensation using an aromatic diamine and an aromatic dicarboxylic acid halide in an N-substituted amide type solvent in order to obtain a high degree of polymerization. (For example, Japanese Patent Publication No. 35-14399). However, in such low-temperature solution polymerization methods, in the case of para-aromatic polyamides, the viscosity of the polymerization system increases rapidly as the polymerization progresses from a low-viscosity monomer liquid, and eventually loses fluidity and becomes solid. However, the degree of polymerization of the polymer in this state is still not at a practical level,
Furthermore, it is necessary to knead the solid reactant to form a fine powder to obtain a polymer having a useful degree of polymerization. For polymerization systems that exhibit rapid phase changes and are required to provide effective stirring and kneading effects suitable for each phase or state, it is necessary to provide the functions required for each phase or state. Continuous polymerization, which can be combined with compatible equipment, is more advantageous and rational than batch polymerization, and compared to batch polymerization, the distribution of the degree of polymerization of the produced polymer is smaller, and the molded products are more The development of a continuous polymerization method for para-aromatic polyamides has been eagerly awaited, as it is expected to have good mechanical properties and has the potential to significantly save labor compared to batch polymerization. However, when performing continuous polymerization by continuously supplying paraphenylenediamine solution and terephthalic acid chloride, the polymerization reaction rate is high, so when the liquid is in a low viscosity state at the initial stage of polymerization, the so-called macro In addition to mixing, highly effective so-called micro-mixing is performed within a few seconds or less to bring the microscopic molar ratio of both monomers to a constant value at all locations in the polymerization system as much as possible to obtain a highly polymerized polymer. Furthermore, in the case of continuous polymerization, in addition to such a rapid mixing function, a function is required to feed the entire amount of the polymerization reaction system to the next step without forming scale at the site where the initial polymerization is performed. In order to improve these shortcomings, U.S. Patent No.
According to No. 3849074 and No. 3850888, mixing of both monomer liquids at the start of polymerization is performed by jetting both monomer liquids at "equal mass velocity" from a jet nozzle and causing them to collide. A mixer with a plunger cleaning structure and continuous polymerization of polyparaphenylene terephthalamide using this mixer have been proposed. However, with this device and method, both macro-mixing and micro-mixing are insufficient, and it is difficult to control the supply of both monomers to achieve "equal mass velocity," which is an important technical point of this method. It has drawbacks. Also, according to Japanese Patent Application Publication No. 53-138498, prepolymer, (Here, n indicates the number average value of all molecules in the system and is 0≦n≦10), an amino group-containing liquid consisting of an N-substituted amide type solvent, and a terephthalic acid dichloride-containing liquid. 500 sec ^-1 so that the molar ratio of the group amino group and the aromatic carboxylic acid chloride group becomes a constant value, and so that the feeding rate of the terephthalic acid dichloride-containing liquid is at least 1.05 times that of the amino group-containing liquid. Continuous polymerization of polyparaphenylene terephthalamide using a mixer in which the reactants are continuously introduced into a mixer having a shear rate of at least 500 sec ^-1 for 1 to 30 seconds at a maximum shear rate of at least 500 sec -1 Proposed. However, even with this method, scaling within the mixer cannot be completely eliminated. [Problems to be solved by the invention] In the devices and methods in the prior art, uniform dispersion of both monomers is insufficiently achieved, and the molar ratio of both monomers, which is the key point of these methods, cannot be kept at a constant value. It is difficult to control the supply, and there are problems with the equipment, such as adhesion of the mixture inside the mixer and scaling. The present invention was completed after extensive research to solve the above-mentioned problems. That is, the present invention
The present invention provides a method for obtaining a polymer with a high degree of polymerization by sufficiently dispersing and mixing both monomers uniformly without impairing the chemical properties of the monomers, and without causing scaling in the mixer. . [Means for Solving the Problems] The present invention provides paraphenylenediamine with one or two selected from the group consisting of N-methyl-2-pyrrolidone, N,N'-dimethylacetamide, and N-acetylpyrrolidine. In a mixture of more than one species,
Substantially equimolar amounts of terephthalic acid dichloride and paraphenylenediamine are dissolved in a solvent system containing calcium chloride or lithium chloride, and the temperature of the mixed solution is maintained at -30°C to -10°C. After adding the mixed solution to a polymerization machine for uniform dispersion and mixing, the mixed solution is continuously fed to a polymerization machine and kneaded until it becomes a powder or granular solid. This is a continuous polymerization method of nylene terephthalamide. When polyparaphenylene terephthalamide is polymerized by the method of the present invention, it is first necessary to prepare a solution in which paraphenylenediamine is dissolved in an N-substituted amide type solvent. N-substituted amide type solvents include N-methyl-2-pyrrolidone, N,
This is a solvent system in which calcium chloride or lithium chloride is added to one or a mixture of two or more selected from the group consisting of N'-dimethylacetamide and N-acetylpyrrolidine. Further, it is preferable that the inorganic salt added at the time of producing the paraphenylenediamine solution is added in the form of fine particles. Note that the polymerization may be carried out in a state where the entire amount of calcium chloride or lithium chloride is not completely dissolved. Next, a solution of paraphenylene diamine dissolved in an N-substituted amide type solvent is cooled to -10°C to -30°C. If the starting temperature is higher than -10°C, the reaction with terephthalic acid dichloride (described later) will raise the temperature and the reaction will proceed rapidly, increasing the degree of polymerization in a short period of time. Scale tends to adhere. If the temperature is lower than -30°C, paraphenylenediamine will precipitate, and the entire system will solidify, making it impossible to handle it as a liquid, resulting in poor operability. When cooling, paraphenylenediamine or/
Although some of the inorganic salts may precipitate, since these are fine particles, there is no problem in polymerization if the system is in a solution state. Terephthalic acid dichloride is added to the cooled solution and mixed. When mixing, it is necessary to remove heat while cooling the mixer, control the addition rate of terephthalic acid dichloride, and control the temperature in the system between -10°C and -30°C. If the temperature in the system is higher than -10°C, scaling within the apparatus is likely to occur, making it difficult to perform continuous supply and making it difficult to stably obtain a polymer with a high degree of polymerization.
If the temperature is below -30°C, the solution will solidify and sufficient mixing will not be possible. The terephthalic acid dichloride to be mixed is preferably added in the form of fine particles or dissolved solution before addition. In some cases, it can also be added as molten liquid terephthalic acid dichloride. The mixing method is preferably carried out batchwise. For example, a solution of paraphenylenediamine dissolved in an N-substituted amide type solvent is placed in a reaction tank equipped with a stirrer, and terephthalic acid dichloride is mixed with stirring. This is done by adding a melt or fine powder. The weight of paraphenylene diamine and terephthalic acid dichloride used in the reaction must be measured with a batch-type weighing machine with an accuracy of ±0.5% or less, preferably ±0.1% or less. The mixing time is chosen in the range of 10 seconds to 10 minutes. Ten
If it is shorter than seconds, sufficient micro-mixing cannot be achieved, and if it is longer than 10 minutes, the reactants may be overheated by the heat of stirring or the viscosity of the reactants may increase, requiring excessive stirring power. I don't like it because I get used to it. The mixed solution thus mixed at a low temperature is continuously fed to a polymerization machine using a quantitative feeder, and kneaded until it becomes a powder or granular solid to proceed with polymerization. The metering feeder referred to herein may be any device that can meter and continuously feed the liquid to the polymerization machine.
For example, plunger type, diaphragm type metering pumps, gear pumps, screw feeders, etc. are used. Even during the process of supplying the solution from the mixing tank to the polymerization machine, the temperature of the solution is preferably maintained at a low temperature, and is preferably cooled to -10°C or lower using jacketed piping or the like. On the other hand, the residence time during this period can be relatively long, and a stock tank can also be installed in the middle. Examples of the polymerization machine include a single-screw or twin-screw extruder, a continuous kneader mixer, and a reciprocating rotary reactor. Among these, the one preferably used is the one disclosed in U.S. Pat. No. 3,195,868;
No. 3198491, also shown in No. 3618902, etc.
This is a so-called "all-surface renewal type continuous two-shaft kneader." The purpose of kneading in the polymerization machine is to raise the degree of polymerization of the reactants to a desired level and complete the polymerization reaction. At this time, the residence time in the polymerization machine, that is, the kneading time, is usually selected within the range of 1 minute to 20 minutes. If it is shorter than 1 minute, sufficient kneading will not be possible.
Only polymers with a low degree of polymerization can be obtained. Furthermore, if the time is longer than 20 minutes, the heat of stirring increases and polymer decomposition is likely to occur. The kneading time can be adjusted by, for example, employing a reactant recycling mechanism, the rotational speed of the kneading blades, the degree of opening of the exit of the polymerizer, the amount of reactants supplied, the number of stages of the polymerizer, and the like. In addition, the degree of kneading strength is approximately
One guideline is 100sec ^-1 or more. It is preferable to keep the temperature of the reactants in the polymerization machine at about 80°C or less, because if the temperature is higher than 80°C, decomposition and side reactions often occur, which are obstacles to obtaining a polymer with a high degree of polymerization. . In order to satisfy this temperature condition, it is preferable to control the temperature of the polymerization machine using a refrigerant such as water, and it is generally preferable to control the temperature to 30°C to 60°C. The polymerization machine is often carried out in one stage, but the same type of polymerization machine as mentioned above,
Alternatively, different devices may be arranged in series in two or more stages as appropriate. The powdered or granular solid polymer thus produced is washed as it is with water, aqueous alkaline solution, acetone, methanol, chloroform, etc., and then dried and isolated as a polymer. The obtained polymer can be molded into fibers, films, fibrils, etc. using a dope prepared by redissolving it in sulfuric acid using a wet molding method or a so-called dry jet wet molding method. These molded products are widely used for both industrial materials and clothing, such as tires, belts,
It is used in fields such as rubber reinforcement materials such as air bags, resin reinforcement materials, heat-resistant clothing, heat-resistant films, heat-resistant paper, hollow fibers, etc., and its high strength, high Young's modulus, heat resistance, flame retardance, etc. Characteristics are fully demonstrated. [Example] Examples are shown below to specifically explain the present invention. The logarithmic viscosity (ηinh) as a guideline for the degree of polymerization shown in the examples is as follows: A solution containing polymer at 0.2g/dl was heated at 35℃.
This was measured using a conventional method. Example 1 N-methyl-2 purified by distillation was placed in a dry stirring tank with a stainless steel jacket having an internal volume of about 5 ml.
- 4.00 kg of pyrrolidone was added in an accurate weighing manner, and then 0.136 kg of powdered anhydrous lithium chloride was added under stirring and dissolved at room temperature. After 1 hour, 0.1728 kg of powdered paraphenylenediamine was accurately weighed and added, and stirring was continued for about 1 hour. Next, a -30°C refrigerant was passed through the jacket of the stirring tank to cool the liquid in the stirring tank to -20°C. Next, 0.3248 kg of terephthalic acid dichloride in powder form was accurately weighed and added under stirring, and added to the jacket of the stirring tank at -30 kg.
The temperature of the internal solution was controlled to be about -10°C and mixed by passing a refrigerant at 0°C. Two minutes after adding terephthalic acid dichloride, the mixed solution was continuously supplied to a container kneader manufactured by Kurimoto Iron Works Co., Ltd. using a gear pump for polymerization. At this time, warm water at 40°C was passed through the jacket of the kneader.
Further, the residence time in the kneader was set to 10 minutes. In this way, continuous polymerization could be carried out for about 1 hour without any trouble. The crumb-like extrudate was sampled every 5 minutes, washed with water, and dried to obtain a polymer, i.e., polyparaphenylene terephthalamide.
are, in order, 6.96, 7.18, 7.27, 7.36, 7.23, 7.35,
They were 7.26, 7.30, and 7.28. Comparative Examples 1 to 4 Using the same equipment and the same raw materials as Example 1,
This article presents the results of experiments in which powdered terephthalic acid dichloride was added to a solution of anhydrous lithium chloride and paraphenylenediamine dissolved in N-methyl-2-pyrrolidone as a solvent, and the temperature at which the mixed solution was varied was varied. It is shown in Table 1. Note that 40°C hot water was passed through the jacket of the container kneader. In addition, the staying time in the kneader was set to 10 minutes.

〔Effect of the invention〕

According to the method of the present invention, by conducting the first stage polymerization in the range of -30°C to -10°C, the polymerization rate is suppressed and a fluid state can be maintained for a long time, so that uniform mixing of monomers is possible. One stage (batch mixing) plus two stages (continuous polymerization) solves the molar balance quantitative feed problem peculiar to continuous polymerization, making it possible to produce polymers with a higher degree of polymerization and more stable quality than conventional completely continuous polymerization. Therefore, it is extremely useful industrially.

Claims (1)

[Claims] 1 Paraphenylenediamine to N-methyl-2-
A solution of one or more selected from the group consisting of pyrrolidone, N,N'-dimethylacetamide, and N-acetylpyrrolidine dissolved in a solvent system in which calcium chloride or lithium chloride is added is added to a parafluorescent solution. Substantially equimolar amounts of terephthalic acid dichloride and enylenediamine are added while maintaining the temperature of the mixed solution at -10°C to -30°C, and the mixed solution is uniformly dispersed and mixed. A continuous polymerization method for polyparaphenylene terephthalamide, which comprises continuously feeding polyparaphenylene terephthalamide into a polymerization machine and kneading it until it becomes a powder or granular solid.