High-heat-dissipation polymerization method of polyisophthaloyl metaphenylene diamine

Abstract

The invention discloses a high heat dissipation polymerization method of poly (m-phenylene isophthalamide), and relates to the technical field of poly (m-phenylene isophthalamide), and the method specifically comprises the following steps: step 1, adding 1 part of m-phenylenediamine solid particles into a 250mL four-mouth jacketed reaction flask, adding a solvent, and stirring until m-phenylenediamine is completely dissolved; step 2, adding 1.878 parts of isophthaloyl dichloride into the N, N-dimethylacetamide solution of m-phenylenediamine, and carrying out a polymerization reaction; and step 3, monitoring the driving current value of the stirring paddle after the N, N-dimethylacetamide solution of isophthaloyl chloride is added, and recording the current at the moment until the driving current value stops increasing. According to the high-heat-dissipation polymerization method of the polyisophthaloyl metaphenylene diamine, the isophthaloyl chloride solution with the mass concentration of 30% is adopted, the isophthaloyl chloride solution can be rapidly dissolved in the system after being added and can be uniformly stirred and uniformly release heat, and the molecular weight distribution of the polyisophthaloyl metaphenylene diamine slurry obtained through polymerization is uniform.

Description

Technical Field

[0001] The invention relates to the technical field of poly(meta-phenylene isophthalamide), in particular to a high heat dissipation polymerization method of poly(meta-phenylene isophthalamide). Background Art

[0002] Referring to a Chinese patent for an intermittent polymerization method for aramid 1313 (publication number CN103113576A), the main purpose is to solve the technical problems of unstable production, low yield, unstable fiber performance, poor dyeing effect, etc. of the 1313 spinning solution in the prior art; the invention dissolves m-phenylenediamine in a polar solvent subjected to cooling treatment by flash distillation purification, and then adds isophthaloyl chloride to obtain a prepolymer solution, adds ammonia to the prepolymer solution to neutralize the hydrogen chloride therein, removes the ammonium chloride therein by a mechanical method, and then adds isophthalic acid to the filtrate to extend the chain to obtain a polymer solution, adds dibutylamine to the polymer solution to neutralize the hydrogen chloride generated by the chain extension polymerization, and the generated salt is dissolved in the polymer solution, and finally the polymer solution is filtered and degassed to obtain a finished product for spinning; the scheme produces PMIA slurry through an intermittent polymerization process, and the main disadvantages are that the time required is more than 5 hours, the operation is cumbersome, and the batches are unstable.

[0003] Referring to a Chinese patent for a method for preparing high-strength and high-modulus meta-aramid ultra-short fibers (publication number CN101736431A), the method comprises the following steps: performing solution polymerization with isophthaloyl chloride and meta-phenylenediamine in a system where an amide compound is an organic solvent to obtain a meta-aromatic polyamide solution containing isophthaloyl meta-phenylenediamine as a repeating unit, neutralizing the hydrochloric acid generated by the reaction with calcium oxide or calcium hydroxide to obtain a spinning solution, and making the inherent logarithmic viscosity of the spinning solution 3-6; and then wet spinning, washing, heat treatment, and winding. High-strength and high-modulus meta-aramid ultra-short fibers with a length of 0.5-20 mm can be obtained by winding, cutting and packaging. The strength and modulus of the meta-aramid ultra-short fibers of the invention are greatly improved compared with existing similar products. The scheme adopts a continuous polymerization process, a method of adding isophthalic acid once and neutralizing once. The method of adding isophthalic acid once has the disadvantage of generating and releasing a large amount of heat in the initial stage of the polymerization reaction. The high heat will affect the reaction rate, thereby resulting in uneven molecular weight distribution of the polymerized PMIA slurry.

[0004] Referring to a method for preparing polyisophthalamide (m-phenylenediamine) spinning solution by low-temperature solution polymerization in a Chinese patent (publication number CN100455706C), the method comprises the following steps: 1) low-temperature solution polymerization of m-phenylenediamine and isophthaloyl chloride in an amide polar organic solvent; 2) neutralization of the hydrogen chloride generated by the reaction with an alkaline earth metal compound, the main feature of which is that the neutralization reaction is carried out in a twin-screw extruder, the alkaline earth metal compound and the unneutralized polymer slurry are quantitatively added to the twin-screw extruder by a feeder to carry out the neutralization reaction in a continuous manner, the reaction temperature is 40-60°C, and the residence time (i.e., reaction time) is only 10-15 minutes. The pH value of the polyisophthalamide spinning solution prepared is 6.0-8.0, and the obtained spinning solution has good filtration performance. The concentration of the polymer in the spinning solution is 18.1wt%, ηinh=1.66-1.68; this scheme adopts a continuous polymerization process, but the neutralizer used is an inorganic metal alkaline oxide (such as sodium hydroxide, calcium oxide). Such substances will produce water during the neutralization process, and the water molecules will have side effects on isophthaloyl chloride, resulting in a lower molecular weight of the PMIA slurry and uneven molecular weight distribution.

[0005] The existing polymerization process of poly(m-phenylene isophthalamide) (PMIA) includes prepolymerization, neutralization, polymerization, neutralization and filtration processes. When preparing a fibrid material during the polymerization process, especially when preparing a slurry with a relative viscosity in the range of 1.2-2.3 dL / g, the polymerization stage generally adopts excessive addition of molten metaphenylene diamine to achieve the goal of controlling the viscosity of the polymerization reaction. However, the addition of molten metaphenylene diamine will lead to local uneven reaction, and the heat released by the reaction is concentrated in the local area and cannot be dissipated, thereby resulting in uneven local molecular weight distribution, which has a great impact on the preparation of fibrid. To this end, the present invention provides a high heat dissipation polymerization method of poly(m-phenylene isophthalamide) to solve the above problems. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention provides a high heat dissipation polymerization method for poly(m-phenylene isophthalamide) to solve the problems mentioned in the above background technology.

[0007] To achieve the above objectives, the present invention is implemented by the following technical scheme: a high heat dissipation polymerization method of poly (m-phenylene isophthalamide), specifically comprising the following steps:

[0008] Step 1: Add 1 part of solid particles of m-phenylenediamine to a 250 mL four-necked jacketed reaction bottle, add a solvent, and stir until the m-phenylenediamine is completely dissolved;

[0009] Step 2: Add 1.878 parts of isophthaloyl chloride to the N,N-dimethylacetamide solution of m-phenylenediamine to carry out polymerization reaction;

[0010] Step 3, monitoring the driving current value of the stirring paddle after adding the N,N-dimethylacetamide solution of isophthaloyl chloride until the driving current value stops increasing, and recording the current at this time;

[0011] Step 4: adding a neutralizing agent to the solution to neutralize the solution;

[0012] Step 5, adjusting the pH value of the reaction system to 4.0-5.5;

[0013] Step 6: Transfer the slurry to a reaction bottle and detect its solid content, and adjust the solid content of the reaction system by adding N,N-dimethylacetamide.

[0014] Preferably, in the step 1, the solvent is N,N-dimethylacetamide, and the water content of N,N-dimethylacetamide does not exceed 20 ppm; the purity of the isophthaloyl chloride and metaphenylenediamine is not less than 99.99%.

[0015] Preferably, in step 1, a low-temperature thermostatic bath is used to cool the jacketed reaction flask, and the refrigerant is an ethylene glycol aqueous solution, so that the temperature of the reagents in the four-necked jacketed reaction flask is lower than -5°C.

[0016] Preferably, in the step 2, the isophthaloyl chloride is in powder form with a concentration of 30%, and is added after drying.

[0017] Preferably, in the step 2, when adding isophthaloyl chloride, the amount added each time does not exceed 1 g, and when the amount of isophthaloyl chloride added reaches 90%, the addition is stopped, ammonia is introduced into the reaction system, and the white ammonium chloride powder in the system is filtered.

[0018] Preferably, in the step 2, the remaining 10% of isophthaloyl chloride is poured into N,N-dimethylacetamide solution for dissolution, and then added into the reaction system.

[0019] Preferably, in the step 2, the reaction temperature in the four-necked jacketed reaction flask is increased to 15° C., and heating or cooling of the reaction system is stopped.

[0020] Preferably, in step 4, the neutralizing agent is a solution of diethylamine or lutidine in N,N-dimethylacetamide.

[0021] Preferably, in step six, the solid content in the reaction system is adjusted to 13.5%-14.5%.

[0022] Beneficial Effects

[0023] The invention provides a high heat dissipation polymerization method of poly(m-phenylene isophthalamide). Compared with the prior art, the method has the following beneficial effects: the high heat dissipation polymerization method of poly(m-phenylene isophthalamide) adopts a 30% mass concentration of isophthaloyl chloride solution, which has the advantages of being able to quickly dissolve in the system after being added, being able to be stirred evenly, and releasing heat evenly, and the molecular weight distribution of the poly(m-phenylene isophthalamide) slurry obtained by polymerization is even; the relative viscosity of the prepared poly(m-phenylene isophthalamide) slurry is within the range of 1.2-2.3 dL / g, the molecular weight distribution of the slurry is normally distributed, and the prepared precipitated fiber has a high quality, which can further improve the indicators of the precipitated fiber, such as the breaking length, the breakdown voltage, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A molecular weight distribution diagram of the slurry obtained in Example 1 of the high heat dissipation polymerization method of poly(m-phenylene isophthalamide) provided in the present invention;

[0025] Figure 2 The molecular weight distribution diagram of the slurry prepared in Comparative Example 1 provided for the high heat dissipation polymerization method of poly(m-phenylene isophthalamide) of the present invention. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Example 1

[0028] A high heat dissipation polymerization method of poly(m-phenylene isophthalamide), specifically comprising the following steps:

[0029] Step 1: Add 1 g of solid m-phenylenediamine particles to a 250 mL four-necked jacketed reaction bottle, and add N,N-dimethylacetamide with a water content of 20 ppm and a purity of 99.99%, stir until the m-phenylenediamine is completely dissolved, and use a low-temperature thermostatic bath to cool the jacketed reaction bottle, and the refrigerant is ethylene glycol aqueous solution, so that the reagent temperature in the four-necked jacketed reaction bottle is -4°C;

[0030] Step 2: Add a total of 1.69 g of isophthaloyl chloride in three portions, observe the temperature in the four-necked reaction bottle to be 20° C. after each addition of isophthaloyl chloride, and ensure that the temperature is cooled to 0° C. before adding the next batch of isophthaloyl chloride, and the speed of the stirring paddle is 2000 rpm; after the addition of isophthaloyl chloride, introduce ammonia gas to neutralize the HCL and filter the neutralization product, ammonium chloride, and the prepolymerization stage is completed;

[0031] In the polymerization stage, 30% isophthaloyl chloride solution was first slowly added, with 0.22 g of isophthaloyl chloride. After stirring for 1 hour, the polymerization reaction was completed, and the slurry was transferred into a sample bottle.

[0032] Example 2

[0033] A high heat dissipation polymerization method of poly(m-phenylene isophthalamide), specifically comprising the following steps:

[0034] Step 1: Add 1 g of solid m-phenylenediamine particles to a 250 mL four-necked jacketed reaction bottle, and add N,N-dimethylacetamide with a water content of 15 ppm and a purity of 99.99%, stir until the m-phenylenediamine is completely dissolved, and use a low-temperature thermostatic bath to cool the jacketed reaction bottle, and the refrigerant is ethylene glycol aqueous solution, so that the reagent temperature in the four-necked jacketed reaction bottle is -3 ° C;

[0035] Step 2: Add a total of 1.69 g of isophthaloyl chloride in three portions, observe the temperature in the four-necked reaction bottle to be 15° C. after each addition of isophthaloyl chloride, and ensure that the temperature is cooled to 0° C. before adding the next batch of isophthaloyl chloride, and the speed of the stirring paddle is 2000 rpm; after the addition of isophthaloyl chloride, introduce ammonia gas to neutralize the HCL and filter the neutralization product, ammonium chloride, and the prepolymerization stage is completed;

[0036] In the polymerization stage, 30% isophthaloyl chloride solution was first slowly added, with 0.20 g of isophthaloyl chloride. After stirring for 1 hour, the polymerization reaction was completed, and the slurry was transferred into a sample bottle.

[0037] Example 3

[0038] A high heat dissipation polymerization method of poly(m-phenylene isophthalamide), specifically comprising the following steps:

[0039] Step 1: Add 1 g of solid m-phenylenediamine particles to a 250 mL four-necked jacketed reaction bottle, and add N,N-dimethylacetamide with a water content of 10 ppm and a purity of 99.99%, and stir until the m-phenylenediamine is completely dissolved. Use a low-temperature thermostatic bath to cool the jacketed reaction bottle, and the refrigerant is ethylene glycol aqueous solution, so that the reagent temperature in the four-necked jacketed reaction bottle is -3 ° C;

[0040] Step 2: Add a total of 1.69 g of isophthaloyl chloride in three portions, observe the temperature in the four-necked reaction bottle to be 10° C. after each addition of isophthaloyl chloride, and ensure that the temperature is cooled to 0° C. before adding the next batch of isophthaloyl chloride, and the speed of the stirring paddle is 2000 rpm; after the addition of isophthaloyl chloride, introduce ammonia gas to neutralize the HCL and filter the neutralization product, ammonium chloride, and the prepolymerization stage is completed;

[0041] In the polymerization stage, 30% isophthaloyl chloride solution was first slowly added, with 0.188 g of isophthaloyl chloride. After stirring for 1 hour, the polymerization reaction was completed, and the slurry was transferred into a sample bottle.

[0042] Comparative Example 1

[0043] 1 g of m-phenylenediamine particles were added to a 250 mL four-necked reaction bottle, and isophthaloyl chloride solvent was added to dissolve, wherein the water content of the solvent N, N-dimethylacetamide was 20 ppm, and the purity of isophthaloyl chloride and m-phenylenediamine was 99.99%. The jacketed reaction bottle was cooled using a low-temperature thermostatic bath until the temperature dropped to -5°C; a total of 1.69 g of isophthaloyl chloride was added in 3 portions, and after each addition of isophthaloyl chloride, the temperature in the four-necked reaction bottle was observed to be 20°C, and the temperature was ensured to be cooled to 0°C before adding the next batch of isophthaloyl chloride, and the speed of the stirring paddle was 2000 rpm; after the addition of isophthaloyl chloride, ammonia was introduced to neutralize the HCL in the reaction, and the neutralization product, ammonium chloride, was filtered, and the prepolymerization stage was completed;

[0044] The amount of isophthaloyl chloride in the polymerization stage was 0.22 g. The polymerization reaction was completed after stirring for 1 hour, and the slurry was transferred into a sample bottle.

[0045] Various parameters of the slurries prepared in Examples 1-3 and Comparative Example 1 were measured; the results are shown in Table 1.

[0046] Table 1

[0047] Slurry type Solid content Acidity (ppm) Relative viscosity Example 1 13.3％ 3285.3 2.31 Example 2 13.3％ 3281.6 2.30 Example 3 13.2％ 3283.1 2.31 Comparative Example 1 13.05％ 3481.5 2.28

[0048] Depend on Figure 1 and Figure 2 It can be seen that the molecular weight distribution of the slurry prepared by adding a 30% isophthaloyl chloride solution of a reagent with a capping effect is compared with the molecular weight distribution of the control group slurry prepared without adding a polymerization inhibitor. After adding the polymerization inhibitor, the molecular weight distribution peak is narrower and the slurry quality is better.

[0049] Meanwhile, the contents not described in detail in this specification belong to the prior art known to those skilled in the art.

[0050] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0051] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high heat dissipation polymerization method of poly(m-phenylene isophthalamide), characterized in that: The specific steps include: Step 1: Add 1 part of solid particles of m-phenylenediamine to a 250 mL four-necked jacketed reaction bottle, add a solvent, and stir until the m-phenylenediamine is completely dissolved; Step 2: Add 1.878 parts of isophthaloyl chloride to the N,N-dimethylacetamide solution of m-phenylenediamine to carry out polymerization reaction; Step 3, monitoring the driving current value of the stirring paddle after adding the N,N-dimethylacetamide solution of isophthaloyl chloride until the driving current value stops increasing, and recording the current at this time; Step 4: adding a neutralizing agent to the solution to neutralize the solution; Step 5, adjusting the pH value of the reaction system to 4.0-5.5; Step 6: Transfer the slurry to a reaction bottle and detect its solid content, and adjust the solid content of the reaction system by adding N,N-dimethylacetamide.

2. The high heat dissipation polymerization method of poly(m-phenylene isophthalamide) according to claim 1, characterized in that: In the step 1, the solvent is N,N-dimethylacetamide, and the water content of N,N-dimethylacetamide does not exceed 20 ppm; the purity of the isophthaloyl chloride and metaphenylenediamine is not less than 99.99%.

3. The high heat dissipation polymerization method of poly(m-phenylene isophthalamide) according to claim 1, characterized in that: In the step 1, a low temperature constant temperature bath is used to cool the jacketed reaction bottle, and the refrigerant is an ethylene glycol aqueous solution, so that the temperature of the reagents in the four-necked jacketed reaction bottle is lower than -5°C.

4. The high heat dissipation polymerization method of poly(m-phenylene isophthalamide) according to claim 1, characterized in that: In the step 2, isophthaloyl chloride is in powder form with a concentration of 30%, and is added after drying.

5. The high heat dissipation polymerization method of poly(m-phenylene isophthalamide) according to claim 1, characterized in that: In the step 2, when adding isophthaloyl chloride, the amount added each time does not exceed 1 g, and when the amount of isophthaloyl chloride added reaches 90%, the addition is stopped, ammonia gas is introduced into the reaction system, and the white ammonium chloride powder in the system is filtered.

6. The high heat dissipation polymerization method of poly(m-phenylene isophthalamide) according to claim 5, characterized in that: In the step 2, the remaining 10% of isophthaloyl chloride is poured into N,N-dimethylacetamide solution for dissolution, and then added into the reaction system.

7. The high heat dissipation polymerization method of poly(m-phenylene isophthalamide) according to claim 1, characterized in that: In the step 2, the reaction temperature in the four-necked jacketed reaction bottle is increased to 15° C., and the heating or cooling of the reaction system is stopped.

8. The high heat dissipation polymerization method of poly(m-phenylene isophthalamide) according to claim 1, characterized in that: In the step 4, the neutralizing agent is a solution of diethylamine or lutidine in N,N-dimethylacetamide.

9. The high heat dissipation polymerization method of poly(m-phenylene isophthalamide) according to claim 1, characterized in that: In the step six, the solid content in the reaction system is adjusted to 13.5%-14.5%.

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