CN102190795A - Method for preparing poly(p-phenylene terephthalamide) - Google Patents

Abstract

The invention discloses a method for preparing poly-p-phenylene terephthalamide, wherein there is an alkane with 3-12 carbon atoms in the reaction system, and the latent heat of vaporization of the alkane is used to transfer the heat of formation of the reaction, Thereby controlling the reaction temperature. This method solves the key engineering problem of heat management in the amplification process of the low-temperature liquid phase polymerization reactor, simplifies the large-scale equipment structure, effectively controls the product quality, has the advantages of simple process operation, easy continuous and large-scale, low energy consumption, and low equipment cost. Significant advantages such as reduction.

Description

Method for preparing poly(p-phenylene terephthalamide)

technical field

The present invention relates to a method for preparing poly-p-phenylene terephthalamide.

Background technique

Polyparaphenylene terephthalamide (also known as aramid 1414, PPTA for short) is a liquid crystal polymer composed of rigid long molecules, which was developed by DuPont in the late 1960s and 1970s. A high-performance synthetic fiber with a golden-yellow metallic thread appearance. Because its molecular chain is highly oriented along the length direction and has a strong interchain bonding force, its strength is greater than 28 g/denier, which is 5 to 6 times that of high-quality steel, and its modulus is 2 to 3 times that of steel or glass fiber. It is 2 times that of steel, and the weight is only 1/5 of steel. The continuous use temperature range is extremely wide, and it can operate normally for a long time in the range of -196°C to 204°C. The shrinkage rate at 150°C is 0, and it does not decompose or melt at a high temperature of 560°C. It has good insulation and corrosion resistance, and has a long life cycle, so it has won the reputation of "synthetic steel wire". It is widely used in the fields of national defense and military industry, aerospace, electromechanical, construction, automobile, marine aquatic products, sporting goods, etc. The annual demand in the world exceeds 500,000 tons.

At present, the preparation method of aramid fiber 1414 is mainly low-temperature solution polycondensation method. That is, first dissolve the acid absorbent (such as pyridine) and solubilizer (such as CaCl ₂ and LiCl) in N-methylpyrrolidone (NMP), after all are dissolved, add a certain amount of p-phenylenediamine, and wait until it is completely dissolved , cooled to -15-5°C with an ice-salt water bath, added terephthaloyl chloride (TPC) in an equimolar amount or slightly more, adjusted to the corresponding stirring speed, and carried out polycondensation until the reaction system gelled, and then The gel is crushed in a certain way, and the residual solvent, solubilizer, hydrochloric acid and acid absorbent are washed away with water, and finally the washed product is dried to obtain powdered aramid fiber 1414.

In this process, the current prior art uses ice-salt bath as a cooling method to control the temperature of the process. However, when the scale of polymerization is relatively large, the area of the simple reactor jacket heat exchange method is limited, and the temperature cannot be controlled very well, so that there is detonation in the reaction process (reaction raw materials are rapidly polymerized into many short-chain polymers in an instant, Accompanied by the rapid increase of the viscosity of the system and the release of a large amount of heat during the process, as well as the risk of decomposing some temperature-sensitive raw materials and generating unnecessary impurities). The method of arranging heat exchange tubes in the polymerization reactor can effectively increase the heat exchange area and control the temperature in principle. However, because the product will eventually gel, it will not only stick to the stirring paddle, but also stick to the heat exchange tube, resulting in a decrease in the heat transfer capacity of the heat exchange tube, and it will also be difficult to control the temperature. At the same time, if a large amount of polymer sticks to the heat exchange tube, it is equivalent to fixing the polymer gel, which also increases the power required for the stirring blade to break the gel again. In addition, if implosion occurs, a large solid block will form in the entire reactor, which will not only affect the uniformity of the product, but also be very difficult to take it out of the reactor. Resulting in poor production continuity. If the twin-screw device is combined in the polymerization process, its huge shear force can effectively break the large solid block formed in the late stage of the polymerization reaction, but the reactants of this system (p-phenylenediamine and terephthaloyl chloride) Sensitive to water or oxygen, not only requires the raw material to be free of water and isolated from oxygen, but also requires extremely high sealing of the device. The twin-screw device is difficult to seal with other equipment due to the existence of a mechanical rotating device, or the sealing is extremely difficult. These engineering reasons make the scale-up production of aramid fiber 1414 very difficult and costly, and there is no mature scale-up production technology at present. Even if it is relatively easy to produce aramid 1313 (meta-aramid fiber, the production process has low viscosity and is relatively easy to control), its single reaction device cannot be too large, and the production efficiency is low, which cannot effectively meet the huge military and civilian markets.

In view of the deficiencies in the above aramid fiber production process, it is hoped to provide a method for easy continuous and large-scale production of aramid fiber.

Contents of the invention

The invention provides a method for preparing poly-p-phenylene terephthalamide, wherein there is an alkane with 3-12 carbon atoms in the reaction system, and the latent heat of vaporization of the alkane is used to transfer the heat of formation of the reaction, Thereby controlling the reaction temperature.

Method of the present invention comprises the following steps:

a. In a stirred vessel add polar solvent, acid absorbent, p-phenylenediamine, co-solvent and alkanes with 3-12 carbon atoms

b. Make the pressure in the container 0.001-1 MPa, add terephthaloyl dichloride accounting for 50%-110% of the moles of p-phenylenediamine.

c. additionally adding terephthaloyl dichloride so that the ratio of the total moles of terephthaloyl chloride added to the moles of p-phenylenediamine is 1:1 to 1:1.1, and react to form a gel.

Detailed ways

The method of the present invention is characterized in that in the synthesis system, through a certain mode of operation or under the presence of inert gas, the latent heat of vaporization of the alkane is used to control the heat transfer of the reaction, and through the emulsification of the alkane and the polymerization solution phase, due to the formed The gel particle size generated by the emulsified droplets is less than 5mm, so as to ensure that the overall viscosity does not increase much during the polymerization process, so that the heat transfer in the reactor is good, the stirring power changes little, the polymerization process temperature is stable, and the reactor is easy to enlarge. After the reaction is over, the alkanes are recovered for recycling.

In one embodiment, the alkane is selected from propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, isohexane, 2,2-dimethylbutane, n-heptane, iso Heptane, neoheptane, 3,3-dimethylpentane, isooctane, nonane, decane, undecane, dodecane and mixtures thereof.

In one embodiment, the method further includes feeding an inert gas or an alkane with 1-3 carbon atoms into the reaction system. Preferably, the inert gas is selected from helium, argon, nitrogen and mixtures thereof, and the alkane with 1-3 carbon atoms is selected from methane, ethane, propane and mixtures thereof.

In one embodiment, the temperature adjustment is achieved by one or more of the following three methods: (1) carrying an alkane with 3-12 carbon atoms with an inert gas or an alkane with 1-3 carbon atoms The alkanes are volatilized; (2) the pressurized operation makes the alkanes with 3-12 carbon atoms liquefied; (3) the depressurized operation makes the alkanes with 3-12 carbon atoms gasified.

In one embodiment, the reaction temperature is -25-5°C.

In one embodiment, the alkane is added to the reaction system at one time.

In one embodiment, the alkane is added in stages and batches according to the temperature feedback of the reaction.

In one embodiment, the method of the invention comprises the steps of:

a. In a stirred vessel add polar solvent, acid absorbent, p-phenylenediamine, co-solvent and alkanes with 3-12 carbon atoms

b. Make the pressure in the container 0.001-1 MPa, add terephthaloyl dichloride accounting for 50%-110% of the moles of p-phenylenediamine.

c. additionally adding terephthaloyl dichloride so that the ratio of the total moles of terephthaloyl chloride added to the moles of p-phenylenediamine is 1:1 to 1:1.1, and react to form a gel.

In one embodiment, terephthaloyl chloride is added as a powder, or as a solution or liquid in a molten state.

In one embodiment, the method of the present invention further comprises the steps of:

d. Break up the formed gel by stirring.

In one embodiment, the method of the present invention further comprises the steps of:

e. Removal of all alkanes with 3-12 carbon atoms.

In a preferred embodiment, the inventive method also comprises the following steps:

j. Filter and wash the broken gel particles.

In one embodiment, the polar solvent is selected from amide polar solvents, and preferably selected from N-methylpyrrolidone, N-ethylpyrrolidone, dimethylamide, dimethylformamide, dimethylacetamide Amide, Dimethylpropanamide, Hexamethyltriamine Phosphate and mixtures thereof.

In one embodiment, the acid absorbent is selected from pyridine, α-picoline, β-picoline, γ-picoline, 2,6-lutidine, triethylamine, liquid ammonia and their mixture. The volume ratio of the acid absorbent to the polar solvent is 0-0.2.

In one embodiment, the co-solvent is selected from LiCl, CaCl ₂ , MgCl ₂ and mixtures thereof.

In one embodiment, in step b, 50%-80% of the moles of p-phenylenediamine are added with terephthaloyl chloride, more preferably 50%-70% of the moles of p-phenylenediamine are added. Diformyl chloride, most preferably adding terephthaloyl chloride accounting for 50%-60% of the moles of p-phenylenediamine.

In one embodiment, the pressure in the vessel in step b is 0.001-0.1 MPa, more preferably 0.001-0.05 MPa.

In one embodiment, the ratio of the total moles of terephthaloyl chloride added in step c to the moles of p-phenylenediamine is 1:1 to 1:1.006.

The relative molecular weight of the obtained polymers in this application is characterized by intrinsic viscosity. The characteristic viscosity test method is to use a general viscosity test method in the art, specifically the test conditions are to use an Ubbelohde viscometer, 98% concentrated sulfuric acid as a solvent, a concentration C=0.5 g/dl, and a test temperature of 30 degrees Celsius.

Compared with the existing technology for producing aramid fiber 1414, the technology provided by the present invention has the following advantages.

1) Using the phase change evaporation heat exchange of liquid alkanes to control the temperature, there is no need to use a large energy-consuming ice-salt bath cooling method, and there is no need to install complicated heat exchange tubes in the polymerization reactor, which can greatly reduce production costs and Equipment manufacturing cost and maintenance cost.

2) By using the liquid alkane emulsification polymerization reaction system, the particle size of the generated polymer aggregates can be controlled below 5mm, which completely avoids the phenomenon of the polymer climbing the pole on the stirring paddle, and can control the smooth discharge of the polymer. Continuous response, and can effectively reduce the motor power used to save power consumption. There is no need to use a twin-screw machine or a polymerization reactor with multiple stirring paddles, which greatly reduces the difficulty of sealing the equipment.

3) By adding liquid saturated hydrocarbon and inert gas together, the heat exchange and emulsification needs of the process can be effectively adjusted, and the operation is very simple. Due to the small particle size of the polymer agglomeration, the remaining reactants TPC and p-phenylenediamine are easy to diffuse Go to the inside of the agglomerates, contact each other, and carry out equimolar polymerization. Compared with the traditional process (generating centimeter-level large blocks), the polymerization effect is better, the time is shorter, and the product quality is high (the intrinsic viscosity is about 2-3 higher).

4) The way of adding liquid saturated hydrocarbon and inert gas together can effectively adjust the heat exchange and emulsification needs of the process, the operation is very simple, and at the end of the reaction, all the liquid saturated hydrocarbon can be taken away by the inert gas without affecting The post-processing process of aramid 1414.

5) Using the method of adding liquid saturated hydrocarbon and inert gas together to adjust the technology required for heat exchange and emulsification in the polymerization process can allow the production of aramid fiber 1414 with a characteristic viscosity of 7-10, and only use traditional technology to produce a characteristic viscosity of 2 -5 products correspond to motors and stirring paddles, which can reduce equipment cost by 50%.

6) Using the method of adding liquid saturated hydrocarbon and inert gas together to adjust the heat transfer and emulsification requirements of the process can be applied to the production line of aramid fiber 1414 with a single device of 10,000 tons/year, which can reduce the production cost of aramid fiber 1414 15-30%.

The following examples are used to further illustrate the present invention, but do not limit the protection scope of the present invention in any way. Those skilled in the art should understand that the protection scope of the present invention is defined by the appended claims.

Example 1

Use a stainless steel stirred tank with a volume of 1 liter, add 100 ml of NMP, 20 ml of pyridine and 80 ml of n-pentane, then add p-phenylenediamine, CaCl ₂ , LiCl, and control the concentration of p-phenylenediamine to 0.2mol/L (in volume of NMP), the mass fraction of _CaCl is 3%, and the mass fraction of LiCl is 0.5%. The nitrogen flow rate is 1.32L/min, and the pressure control in the reactor is 0.1MPa (absolute pressure). When the solution temperature is -2°C, add powdered TPC with 50.06% total moles of p-phenylenediamine, the reaction temperature rises to 4°C, increases the nitrogen flow to 6L/min, lowers the solution temperature to -6°C, and then adds For powdery TPC with 50% total moles of p-phenylenediamine, the reaction temperature rises to 1.2°C. After 2 minutes, a gel is formed, and the particle size range of the gel is 1-3mm, and the average particle size is 2.8mm. Increase the stirring power by 30% to break the gel, and then increase the nitrogen flow rate to 13.2 L/min to take out all the n-pentane in the system. The obtained gel particles are filtered, washed, and all impurities are removed to obtain a product with an intrinsic viscosity of 7.5.

Example 2

Use a stainless steel stirred tank with a volume of 100 liters, add 30 liters of NMP, 3 liters of pyridine, 20 liters of n-pentane and 25 liters of n-hexane, and then add p-phenylenediamine, CaCl ₂ and LiCl to control the concentration of p-phenylenediamine 0.8mol/L (by volume of NMP), the massfraction of _CaCl2 is 2%, the massfraction of LiCl is 1%, the argon flow rate is ^0.5m /min, and the pressure control in the reactor is 0.1MPa (absolute pressure). When the solution temperature is -4°C, add powdered TPC with 50% total moles of p-phenylenediamine, the reaction temperature rises to 4.5°C, the argon flow rate is increased to 3m ³ /min and the solution temperature is lowered to -2°C, Then add powdered TPC with 50% p-phenylenediamine in total moles, react to 1.2° C., and form a gel after 6 minutes. The particle size range of polymer aggregates is 1-3 mm, with an average particle size of 2.3 mm. Increase the stirring power by 30% to break the gel. Then increase the argon flow rate to 4.8m ³ /min to take out all the n-pentane and n-hexane in the system. The obtained gel particles are filtered and washed to remove all impurities, and the intrinsic viscosity of the obtained product is 8.5.

Example 3

Use a stainless steel stirred tank with a volume of 10 liters, add 4 liters of NMP, 0.5 liters of pyridine, 0.6 liters of isopentane and 1 liter of neohexane, and then add p-phenylenediamine, CaCl ₂ , LiCl to control the concentration of p-phenylenediamine Concentration is 0.1mol/L (in the volume meter of NMP), and the massfraction of _CaCl2 is 1%, and the massfraction of LiCl is 0.4%, and helium flow rate is 36L/min, and the pressure control in the reactor is 0.1MPa (absolute pressure ). When the solution temperature is -15°C, add TPC (concentration: 0.1mol/L) dissolved in NMP which is equimolar to p-phenylenediamine within 4 minutes, the reaction temperature rises to 4.5°C, and the helium flow rate is increased The temperature of the solution was lowered to -5°C to 0.1 m ³ /min. After 5 minutes, a gel is formed, the particle size range of the gel is 0.5-3.5 mm, and the average particle size is 1.8 mm. Increase the stirring power by 20% to break the gel. Then increase the helium flow rate to 0.2m ³ /min to take out all the isopentane and neohexane in the system. Filter the obtained gel particles, wash them, and remove all impurities, and the characteristic viscosity of the product obtained is 7.8 .

Example 4

Using a stainless steel stirred tank with a volume of 1 liter, add 100 ml of NMP, 10 ml of pyridine, 200 ml of n-hexane and 150 ml of 2,3-dimethylbutane, then add p-phenylenediamine and CaCl ₂ , LiCl, control The concentration of p-phenylenediamine is 0.2mol/L (in the volume of NMP), the mass fraction of _CaCl is 3%, the mass fraction of LiCl is 0.6%, and the total flow of methane and nitrogen is 2L/min (methane and nitrogen volume The ratio is 1:2), and the pressure in the reactor is controlled to be 0.1MPa (absolute pressure). When the solution temperature is -25°C, add powdered TPC with 80% total moles of p-phenylenediamine, the reaction temperature rises to 3°C, the total flow rate of methane and nitrogen is increased to 7.6L/min, and the solution temperature is reduced to -2°C, then add powdered TPC with 20% total moles of p-phenylenediamine, and the reaction rises to 2°C. After 3 minutes, a gel is formed, and the particle size range of the gel is 1-4mm, and the average particle size is 1.5mm. Increase the stirring power by 10% to break the gel. Then increase the total flow of methane and nitrogen to 26L/min, and take out all n-hexane and 2,3-dimethylbutane in the system. The obtained gel particles are filtered and washed to remove all impurities, and the characteristic viscosity of the obtained product is greater than 7.3.

Example 5

Using a glass stirred tank with a volume of 1 liter, add 200 ml of NMP, 30 ml of pyridine, 200 ml of isohexane and 100 ml of neohexane, then add p-phenylenediamine and CaCl ₂ to control the concentration of p-phenylenediamine to 0.36 mol/L (in the volume of NMP), the mass fraction of _CaCl2 is 5%, the total flow of ethane and propane is 3.8L/min (the volume ratio of ethane and propane is 1: 3), the pressure in the reactor The control is 0.2MPa (absolute pressure). When the solution temperature is -12°C, add powdered TPC with 50.03% total moles of p-phenylenediamine, raise the reaction temperature to 3°C, increase the total flow rate of ethane and propane to 7L/min, and lower the solution temperature to - 2°C, then add powdered TPC with 50% total moles of p-phenylenediamine, and the reaction rises to 3.5°C. After 6 minutes, a gel is formed, and the particle size range of the gel is 1-4.5mm, and the average particle size is 2.8mm. Increase the stirring power by 10% to break the gel. Then increase the total flow of ethane and propane to 10L/min to take out all the new hexane and isohexane in the system. The obtained gel particles are filtered and washed to remove all impurities, and the characteristic viscosity of the obtained product is >10.

Example 6

Use a stainless steel stirred tank with a volume of 500 liters, add 100 liters of NMP, 14 liters of pyridine, 100 liters of isopentane and 50 liters of n-pentane, and then add p-phenylenediamine, CaCl ₂ , LiCl to control the concentration of p-phenylenediamine Concentration is 0.24mol/L (in the volume meter of NMP), the massfraction of CaCl ₂ is 3%, the massfraction of LiCl is 1%, methane flow rate is 1.6m ³ /min, and the pressure control in the reactor is 0.1MPa (absolute pressure). When the solution temperature is -10°C, add TPC (concentration is 0.24mol/L) dissolved in NMP in equimolar number with p-phenylenediamine within 10 minutes, the reaction temperature rises to 2.5°C, and the methane flow rate is increased to 4m ³ /min to reduce the solution temperature to -5°C. After 8 minutes, a gel is formed, the particle size range of the gel is 0.5-5 mm, and the average particle size is 3 mm. Increase the stirring power by 30% to break the gel, and then maintain the flow of methane to take out all the isopentane and n-pentane in the system. The obtained gel particles are filtered, washed, and after removing all impurities, the characteristic viscosity of the product obtained is >7.5.

Example 7

Use a stainless steel stirred tank with a volume of 500 liters, add 150 liters of NMP, 20 liters of pyridine and 200 liters of n-hexane, then add p-phenylenediamine and CaCl ₂ , LiCl, and control the concentration of p-phenylenediamine to be 0.3mol/L ( In terms of the volume of NMP), the mass fraction of _CaCl is 3.8%, the mass fraction of LiCl is 0.8%, and the flow of methane, ethane and propane is ^3m /min (the volume ratio of methane and ethane to propane is 2: 1:1), the pressure inside the reactor is controlled to be 0.3MPa (absolute pressure). When the solution temperature is -5°C, add powdered TPC with 50% total moles of p-phenylenediamine, the reaction temperature rises to 4°C, and the total flow rate of methane, ethane and propane is increased to 20m ³ /min to lower the solution temperature Decrease to -4°C, then add powdered TPC with 50% total moles of p-phenylenediamine, and the reaction rises to 3°C. After 5 minutes, a gel is formed, and the particle size range of the gel is 1-4mm, and the average particle size is 2.8mm. Increase the stirring power by 30% to break the gel. Then keep the total flow of methane, ethane and propane, gradually reduce the system pressure to 0.1MPa (absolute pressure), and take out all the normal hexane in the system. The obtained gel particles are filtered and washed to remove all impurities, and the characteristic viscosity of the obtained product is >7.

Example 8

Use a stainless steel stirred tank with a volume of 500 liters, add 180 liters of NMP, 30 liters of pyridine and 130 liters of n-pentane, then add p-phenylenediamine, CaCl ₂ , LiCl, and control the concentration of p-phenylenediamine to 0.28mol/L (in volume of NMP), the mass fraction of _CaCl is 3.6%, the mass fraction of LiCl is 0.3%, methane and helium flow rate is ^3m /min (the volume ratio of methane and helium is 1: 1), the reaction The pressure in the kettle is controlled to be 0.1MPa (absolute pressure). When the solution temperature is -9°C, add powdered TPC with 70% total moles of p-phenylenediamine, the reaction temperature rises to 2°C, the total flow of methane and helium is increased to 6m ³ /min and the solution temperature is reduced to -5°C, then add 50 liters of n-pentane and powdered TPC with 30% p-phenylenediamine in total moles, and the reaction rises to 2.5°C. After 4 minutes, a gel is formed, the particle diameter of the gel is in the range of 1-5mm, and the average particle diameter is 2.0mm. Increase the stirring power to 25% to break the gel. Keep the total flow of methane and helium at 14m ³ /min, and take out all n-pentane in the system. The obtained gel particles are filtered and washed to remove all impurities, and the characteristic viscosity of the obtained product is greater than 7.6.

Example 9

Use a stainless steel stirred tank with a volume of 500 liters, add 180 liters of NMP, then add p-phenylenediamine and CaCl ₂ , LiCl, control the concentration of p-phenylenediamine to be 0.28mol/L (by volume of NMP), CaCl ₂ The mass fraction of LiCl is 3.6%, the mass fraction of LiCl is 0.2%, the pressure control in the reactor is 1MPa (absolute pressure), adds 30 liters of propane, inert gas is methane and helium, and its flow rate is ^3m /min (methane and helium The volume ratio of helium is 1:1). When the solution temperature is -9°C, add powdered TPC with 70% total moles of p-phenylenediamine, the reaction temperature rises to 2°C, propane evaporates naturally to lower the solution temperature to -5°C, and then adds total p-phenylenediamine For 30% mole percent powdered TPC, the reaction was raised to 2.5°C. After 4 minutes, a gel is formed, and the particle size range of the gel is 1-5 mm, and the average particle size is 2.3 mm. Increase the stirring power to 25% to break the gel. Keep the total flow rate of methane and helium at 14m ³ /min, slowly reduce the system pressure to 0.1MPa (absolute pressure), and let all the propane in the system vaporize and escape from the reactor. The obtained gel particles are filtered and washed to remove all impurities, and the characteristic viscosity of the obtained product is greater than 8.4.

Example 10

Use a stainless steel stirred tank with a volume of 500 liters, add 180 liters of NMP, then add p-phenylenediamine and CaCl ₂ , control the concentration of p-phenylenediamine to be 0.28mol/L (by volume of NMP), the quality of CaCl ₂ The fraction is 3.6%, the pressure in the reactor is controlled to be 0.1MPa (absolute pressure), 220 liters of butane is added, and when the solution temperature is 0°C, the molten TPC of 80% of the total moles of p-phenylenediamine is added, and the reaction temperature rises When the temperature reaches 5°C, butane evaporates naturally to reduce the solution temperature to 0°C, then add molten TPC with 20% total moles of p-phenylenediamine, and the reaction rises to 4.5°C. After 7 minutes, a gel is formed, the particle diameter of the gel is in the range of 1-5mm, and the average particle diameter is 3.0mm. Increase the stirring power to 28% to break the gel. Slowly reduce the system pressure to vaporize all the butane in the system and escape from the reactor. The obtained gel particles are filtered and washed to remove all impurities, and the characteristic viscosity of the obtained product is >8.6.

Example 11

Use a stainless steel stirred tank with a volume of 500 liters, add 180 liters of NMP, then add p-phenylenediamine and CaCl ₂ , LiCl, control the concentration of p-phenylenediamine to be 0.26mol/L (by volume of NMP), CaCl ₂ The mass fraction of LiCl is 3.4%, the mass fraction of LiCl is 0.9%, the pressure control in the reactor is 0.01MPa (absolute pressure), adds 260 liters of hexanes, when solution temperature is-15 ℃, adds p-phenylenediamine total mole Add 80% molten TPC, the reaction temperature rises to 2°C, the natural evaporation of hexane reduces the solution temperature to -5°C, and then adds 20% molten TPC in total moles of p-phenylenediamine, and the reaction rises to 4.5°C. After 7 minutes, a gel is formed, the particle diameter of the gel is in the range of 1-5mm, and the average particle diameter is 3.0mm. Increase the stirring power to 28% to break the gel. Maintain system pressure and allow any hexane vapor in the system to escape the reactor. The obtained gel particles are filtered and washed to remove all impurities, and the characteristic viscosity of the obtained product is greater than 9.6.

Example 12

Use a stainless steel stirred tank with a volume of 1 liter, add 100 ml of NMP, 18 ml of pyridine, 80 ml of n-heptane and 80 ml of isooctane, then add p-phenylenediamine, CaCl ₂ , LiCl, to control the concentration of p-phenylenediamine Concentration is 0.3mol/L (in the volume meter of NMP), and the massfraction of _CaCl2 is 4%, and the massfraction of LiCl is 1.2%. The nitrogen flow rate is 6L/min, and the pressure control in the reactor is 0.001MPa (absolute pressure ). When the solution temperature is -2°C, add powdered TPC with 50.06% total moles of p-phenylenediamine, increase the reaction temperature to 5°C, increase the nitrogen flow to 12L/min, lower the solution temperature to -6°C, and then add For powdery TPC with 50% total moles of p-phenylenediamine, the reaction temperature rises to 1.2°C. After 2 minutes, a gel is formed, and the particle size range of the gel is 1-3mm, and the average particle size is 2.8mm. Increase the stirring power by 30% to break the gel, and then increase the nitrogen flow rate to 16L/min to take out all the alkanes in the system. The obtained gel particles are filtered, washed, and all impurities are removed to obtain a product with an intrinsic viscosity of 7.8.

Example 13

Using a stainless steel stirred tank with a volume of 1 liter, add 150 ml NMP, 15 ml pyridine, 80 ml isoheptane, 20 ml neoheptane and 50 ml 3,3-dimethylpentane, then add p-phenylenediamine With CaCl ₂ , LiCl, the concentration of control p-phenylenediamine is 0.24mol/L (in the volume of NMP), CaCl ₂ mass fraction is 3.6%, the mass fraction of LiCl is 0.8%, nitrogen flow is 6L/min, reaction The pressure in the kettle is controlled to be 0.05MPa (absolute pressure). When the solution temperature is -10°C, add powdered TPC with 60.06% total moles of p-phenylenediamine, increase the reaction temperature to 5°C, increase the nitrogen flow rate to 12L/min, lower the solution temperature to -6°C, and then add For powdery TPC with 40% total moles of p-phenylenediamine, the reaction temperature is raised to 5°C. After 5 minutes, a gel is formed, and the particle size range of polymer aggregates is 1-5 mm, with an average particle size of 3.8 mm. Increase the stirring power by 35% to break the gel, keep the nitrogen flow, and take out all the alkanes in the system. After the obtained gel particles are filtered and washed to remove all impurities, the characteristic viscosity of the obtained product is greater than 6.8.

Example 14

Use a stainless steel stirred tank with a volume of 500 liters, add 150 liters of NMP, 15 liters of pyridine, 250 liters of neoheptane, then add p-phenylenediamine and CaCl ₂ , control the concentration of p-phenylenediamine to be 0.8mol/L (with The volume of NMP), the mass fraction of _CaCl2 is 5%, the methane flow rate is ^2m3 /min, and the pressure control in the reactor is 0.05MPa (absolute pressure). When the solution temperature is -12°C, add molten TPC with 60.06% total moles of p-phenylenediamine, the reaction temperature rises to 4°C, the nitrogen flow rate is increased to 4m ³ /min, the solution temperature is reduced to -6°C, and then Add molten TPC with 40% total moles of p-phenylenediamine, and the reaction rises to 3°C. After 4 minutes, a gel was formed, and the particle size range of the polymer aggregates was 1-5 mm, with an average particle size of 3.5 mm. Increase the stirring power by 35% to break the gel, maintain the methane flow rate and system pressure, and take out all the new heptane in the system. The obtained gel particles are filtered and washed to remove all impurities, and the characteristic viscosity of the obtained product is greater than 7.3.

Claims (25)

1. wherein there is the alkane with 3-12 carbon atom in method for preparing PPTA in reaction system, utilize the latent heat of vaporization of described alkane to come the generation heat of shift reaction, thus control reaction temperature.

2. the method for claim 1, wherein said alkane is selected from propane, normal butane, Trimethylmethane, Skellysolve A, iso-pentane, normal hexane, isohexane, 2,2-dimethylbutane, normal heptane, isoheptane, neoheptane, 3,3-dimethylpentane, octane-iso, nonane, decane, undecane, dodecane and their mixture.

3. claim 1 or 2 method, it also comprises the alkane that feeds rare gas element or have 1-3 carbon atom in reaction system.

4. the method for claim 3, wherein said rare gas element is selected from helium, argon gas, nitrogen and their mixture.

5. claim 3 or 4 method, the alkane of the wherein said 1-3 of a having carbon atom is selected from methane, ethane, propane and their mixture.

6. the method for one of claim 1-5, wherein said temperature regulation realizes by in following three kinds of modes one or more: (1) carries the alkane volatilization with 3-12 carbon atom with rare gas element or alkane with 1-3 carbon atom; (2) pressurized operation makes the alkane liquefaction with 3-12 carbon atom; (3) decompression operation makes the alkane gasification with 3-12 carbon atom.

7. the method for one of claim 1-6, described temperature of reaction be-25-5 ℃.

8. the method for one of claim 1-7 is wherein with in the disposable adding reaction system of described alkane.

9. the method for one of claim 1-8 wherein according to the Temperature Feedback of reaction, adds described alkane stage by stage in batches.

10. the method for one of claim 1-9, it may further comprise the steps:

A. in the container that stirs, add polar solvent, acid absorber, Ursol D, solubility promoter and have the alkane of 3-12 carbon atom,

B. making the pressure in the container is 0.001-1MPa, add to account for the p-phthaloyl chloride that the Ursol D mole number is 50%-110%,

C. add p-phthaloyl chloride in addition, make that institute adds the total mole number of p-phthaloyl chloride and the ratio of Ursol D mole number is 1: 1 to 1: 1.1, react the formation gel.

11. the method for claim 10, wherein p-phthaloyl chloride adds with powder type, and perhaps the liquid form with solution or molten state adds.

12. the method for claim 10 or 11, it is further comprising the steps of:

D. formed gel is broken by stirring.

13. the method for one of claim 10-12, it is further comprising the steps of:

E. remove the alkane that all has 3-12 carbon atom.

14. the method for one of claim 10-13, it is further comprising the steps of:

J. the gel particle with fragmentation filters, washs.

15. the method for one of claim 10-14, wherein said polar solvent is selected from the amides polar solvent.

16. the method for one of claim 10-15, wherein said polar solvent are selected from N-Methyl pyrrolidone, N-ethyl pyrrolidone, dimethyl formamide, N,N-DIMETHYLACETAMIDE, dimethyl propylene acid amides, hexamethylphosphoric acid triamide and their mixture.

17. the method for one of claim 10-16, wherein said acid absorber are selected from pyridine, α-Jia Jibiding, beta-picoline, γ-picoline, 2,6-lutidine, triethylamine, liquefied ammonia and their mixture.

18. the method for one of claim 10-17, wherein said solubility promoter is selected from LiCl, CaCl ₂, MgCl ₂With their mixture.

19. the method for one of claim 10-18, wherein adding accounts for the p-phthaloyl chloride that the Ursol D mole number is 50%-80% in step b.

20. the method for one of claim 10-19, wherein adding accounts for the p-phthaloyl chloride that the Ursol D mole number is 50%-70% in step b.

21. the method for one of claim 10-20, wherein adding accounts for the p-phthaloyl chloride that the Ursol D mole number is 50%-60% in step b.

22. the method for one of claim 10-21, wherein the pressure in the container is 0.001-0.1MPa in step b.

23. the method for one of claim 10-22, wherein the pressure in the container is 0.001-0.05MPa in step b.

24. the method for one of claim 10-23, wherein adding the total mole number of p-phthaloyl chloride and the ratio of Ursol D mole number in step c is 1: 1 to 1: 1.006.

25. the method for one of claim 10-24, the volume ratio of wherein said acid absorber and polar solvent are 0-0.2.