A crystallization method for large-particle nylon 10T salt

Abstract

The invention discloses a crystallization method for large-particle nylon 10T salt, comprising the following steps: preparing a decanediamine aqueous solution and a terephthalic acid dispersion; adding the decanediamine aqueous solution to the terephthalic acid dispersion under stirring; charging nitrogen or inert gas into a second jacketed reactor to make the pressure 0.4MPa-0.6MPa, raising the temperature of the liquid in the reactor to 130-160°C, and reacting for 2-5 hours; lowering the temperature of the liquid in the jacketed reactor to 120-125°C, adding nylon 10T salt seeds, and continuing to lower the temperature to 100-119°C; then lowering the temperature in the jacketed reactor to 20-70°C at a cooling rate of 2°C / min-5°C / min, and centrifuging to obtain large-particle nylon 10T salt. Compared with commercially available nylon 10T salt, the large-particle nylon 10T salt has large particle size, uniform particle size distribution, low water content, high yield, easy solid-liquid separation during production, and reduced energy consumption.

Description

Technical Field

[0001] The invention belongs to the technical field of material synthesis, and in particular relates to a crystallization method of large-particle nylon 10T salt. Background Art

[0002] The rapid development of the electrical and electronic and automotive fields has led to a sharp increase in the demand for polyamide, making it the largest and most widely used engineering plastic. Semi-aromatic polyamides (such as nylon 6T, nylon 9T, nylon 10T, etc.) have been widely used in automotive parts, mechanical parts, and electrical and electronic components due to their excellent thermal properties, chemical resistance, dimensional stability, and good processability.

[0003] The first stage of industrial production of semi-aromatic polyamides is usually the salt-forming process, which can be divided into organic solvent salt-forming and water solvent salt-forming according to the different solvent media. For example, patent CN101456804A discloses the use of organic solvent salt-forming to prepare semi-aromatic nylon salts with N-methylpyrrolidone or dimethylformamide as solvents, and patent CN101880235A discloses the use of dimethyl sulfoxide as solvent to prepare semi-aromatic nylon salts. Although organic solvent salt-forming can prepare high-quality nylon salts, the prepared nylon salts are in the form of white powders with a small particle size distribution, which makes it difficult to separate nylon salts from organic solvents, and the recovery of organic solvents will increase production costs and cause certain environmental pollution.

[0004] Water solvent salt formation has the advantages of non-toxicity, cheap and easy to obtain, and has gradually replaced organic solvents to prepare semi-aromatic nylon salts. For example, patents CN1887841A, CN103613495B, EP0411790A1, and CN103724209A all use water as solvent to prepare nylon salts. However, when using water as solvent to prepare nylon 10T salt, since the mass fraction of nylon 10T salt in boiling water under normal pressure is only 5.7%, the cooling crystallization output is too small, and it is not suitable for large-scale industrial production. In order to increase the mass fraction of nylon 10T salt in water solvent, the measures of increasing temperature and pressure can be taken to increase the solubility of nylon 10T salt in water. For example, patent CN103724209A uses water as solvent, and prepares nylon 10T salt by cooling crystallization under high temperature and high pressure conditions, and its yield is 93%. However, under high temperature and high pressure conditions, the solubility of nylon 10T salt in water increases sharply, and explosive nucleation occurs during the cooling crystallization process, resulting in small particle size of the obtained nylon salt, difficulty in solid-liquid separation, and high water content of the product. In addition, during the solid-liquid separation process, a portion of the nylon 10T salt will exist in the centrifuged mother liquor, which reduces the yield of the obtained product. As described in patent CN103724209A, the yield of nylon 10T salt does not exceed 93%. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for crystallizing large-particle nylon 10T salt with low moisture content and high yield.

[0006] The technical solution of the present invention is summarized as follows:

[0007] A method for crystallizing large-particle nylon 10T salt comprises the following steps:

[0008] 1) adding deionized water and decanediamine in a mass ratio of 1.5 to 2:1 to a jacketed reactor replaced with nitrogen or an inert gas under stirring at 100 to 200 rpm, introducing steam into the jacket of the jacketed reactor to raise the temperature of the liquid in the jacketed reactor to 80° C. to 100° C., and obtaining a clear decanediamine aqueous solution;

[0009] 2) adding deionized water and terephthalic acid in a mass ratio of 3 to 4:1 to the second jacketed reactor replaced with nitrogen or inert gas under stirring at 300 to 400 rpm, introducing steam into the jacket of the second jacketed reactor to raise the temperature of the liquid in the second jacketed reactor to 80° C. to 100° C., and stirring for 60 min to 120 min to obtain a terephthalic acid dispersion;

[0010] 3) under stirring at 300 to 400 rpm, the decanediamine aqueous solution is added to the terephthalic acid dispersion at a rate of 60 mL / min to 120 mL / min in a molar ratio of decanediamine to terephthalic acid of 1.1 to 1.2:1; after the addition is completed, nitrogen or inert gas is charged into the second jacketed reactor to make the pressure 0.4 MPa to 0.6 MPa, and steam is then introduced into the jacket of the second jacketed reactor to raise the liquid temperature in the reactor to 130° C. to 160° C., and the reaction is carried out for 2 to 5 hours to obtain a clear reaction solution;

[0011] 4) The solution obtained in step 3) is stirred at 100 to 200 rpm, and circulating cooling water is introduced into the jacket of the second jacketed reactor to reduce the temperature of the liquid in the jacketed reactor to 120 to 125°C at a cooling rate of 0.3°C / min to 0.8°C / min, and nylon 10T salt seed crystals are added, and the temperature in the jacketed reactor is further reduced to 100 to 119°C at a cooling rate of 0.3°C / min to 0.8°C / min; the temperature in the jacketed reactor is then reduced to 20 to 70°C at a cooling rate of 2°C / min to 5°C / min, and centrifuged to obtain large particles of nylon 10T salt.

[0012] The inert gas is helium or argon.

[0013] The added mass of the nylon 10T salt seed crystals is 0.02% of the sum of the mass of decanediamine and terephthalic acid.

[0014] Advantages of the present invention:

[0015] Compared with commercially available nylon 10T salt, the large-particle nylon 10T salt obtained by the method of the present invention has the advantages of large particle size, uniform particle size distribution, low water content, high yield, etc., and solid-liquid separation is easy during the production process, which can reduce the energy consumption of solid-liquid separation and is suitable for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The figure is a comparison of the appearance of commercially available nylon 10T salt (A) and the large-particle nylon 10T salt (B) obtained in Example 1.

[0017] Figure 2 The figure is a comparison chart of the particle size distribution of the product obtained by the present invention and the particle size distribution of commercially available nylon 10T salt. DETAILED DESCRIPTION

[0018] The present invention will be further described below by means of specific examples.

[0019] Example 1

[0020] A method for crystallizing large-particle nylon 10T salt comprises the following steps:

[0021] 1) under stirring at 200 rpm, 1520 kg of deionized water and 1000 kg of decanediamine (5.8 kilomol) were added to a jacketed reactor after nitrogen replacement three times, steam was introduced into the jacket of the jacketed reactor to raise the temperature of the liquid in the jacketed reactor to 90° C., and the solution was stirred until it became clear to obtain a clear decanediamine aqueous solution;

[0022] 2) under stirring at 400 rpm, 2415 kg of deionized water and 805 kg (4.8 kilomol) of terephthalic acid (the molar ratio of decanediamine to terephthalic acid is about 1.2:1) were added to the second jacketed reactor after nitrogen replacement three times, steam was introduced into the jacket of the second jacketed reactor to raise the temperature of the liquid in the second jacketed reactor to 90° C., and stirred for 120 min to obtain a terephthalic acid dispersion;

[0023] 3) under stirring at 400 rpm, adding the decanediamine aqueous solution to the terephthalic acid dispersion at a rate of 120 mL / min; after the addition, nitrogen was charged into the second jacketed reactor to make the pressure 0.6 MPa, and then steam was introduced into the jacket of the second jacketed reactor to raise the liquid temperature in the reactor to 160° C., and reacted for 2 hours to obtain a clear reaction solution;

[0024] 4) The solution obtained in step 3) is stirred at 200 rpm, and circulating cooling water is introduced into the jacket of the second jacketed reactor to reduce the temperature of the liquid in the jacketed reactor to 125°C at a cooling rate of 0.8°C / min, and 364 g of commercially available powdered nylon 10T salt seed is added, and the temperature in the jacketed reactor is further reduced to 119°C at a cooling rate of 0.8°C / min; the temperature in the jacketed reactor is then reduced to 70°C at a cooling rate of 5°C / min, and centrifuged to obtain large particles of nylon 10T salt.

[0025] The product obtained by centrifugation is weighed, the product yield is calculated, and the product particle size distribution is measured. Figure 1 , Figure 2 and Table 1.

[0026] Example 2

[0027] A method for crystallizing large-particle nylon 10T salt comprises the following steps:

[0028] 1) under stirring at 100 rpm, 2120 kg of deionized water and 1212 kg (7.0 kmol) of decanediamine were added to a jacketed reactor after three replacements with helium, steam was introduced into the jacket of the jacketed reactor to raise the temperature of the liquid in the jacketed reactor to 80° C., and the solution was stirred until it became clear to obtain a clear decanediamine aqueous solution;

[0029] 2) under stirring at 300 rpm, 3675 kg of deionized water and 1050 kg (6.3 kilomol) of terephthalic acid (the molar ratio of decanediamine to terephthalic acid is about 1.1:1) were added to the second jacketed reactor after helium replacement three times, steam was introduced into the jacket of the second jacketed reactor to raise the temperature of the liquid in the second jacketed reactor to 80° C., and stirred for 60 min to obtain a terephthalic acid dispersion;

[0030] 3) under stirring at 300 rpm, the decanediamine aqueous solution was added to the terephthalic acid dispersion at a rate of 60 mL / min; after the addition was completed, helium was charged into the second jacketed reactor to make the pressure 0.4 MPa, and then steam was introduced into the jacket of the second jacketed reactor to raise the liquid temperature in the reactor to 130° C., and a clear reaction solution was obtained after reacting for 5 hours;

[0031] 4) The solution obtained in step 3) is stirred at 100 rpm, and circulating cooling water is introduced into the jacket of the second jacketed reactor to reduce the temperature of the liquid in the jacketed reactor to 120°C at a cooling rate of 0.3°C / min, and 452 g of commercially available powdered nylon 10T salt seed is added, and the temperature in the jacketed reactor is further reduced to 100°C at a cooling rate of 0.3°C / min; the temperature in the jacketed reactor is then reduced to 20°C at a cooling rate of 2°C / min, and centrifuged to obtain large particles of nylon 10T salt.

[0032] The product obtained by centrifugation is weighed, the product yield is calculated, and the product particle size distribution is measured. Figure 2 and Table 1.

[0033] Example 3

[0034] A method for crystallizing large-particle nylon 10T salt comprises the following steps:

[0035] 1) Under stirring at 150 rpm, 3040 kg of deionized water and 1520 kg (8.8 kilomol) of decanediamine were added to a jacketed reactor after three replacements with argon, steam was introduced into the jacket of the jacketed reactor to raise the temperature of the liquid in the jacketed reactor to 100° C., and the solution was stirred until it became clear to obtain a clear decanediamine aqueous solution;

[0036] 2) under stirring at 300 rpm, 5040 kg of deionized water and 1260 kg (7.6 kilomol) of terephthalic acid (the molar ratio of decanediamine to terephthalic acid is about 1.16:1) were added to the second jacketed reactor after argon was replaced three times, steam was introduced into the jacket of the second jacketed reactor to raise the temperature of the liquid in the second jacketed reactor to 100° C., and stirred for 90 min to obtain a terephthalic acid dispersion;

[0037] 3) under stirring at 350 rpm, the decanediamine aqueous solution was added to the terephthalic acid dispersion at a rate of 90 mL / min; after the addition was completed, argon was charged into the second jacketed reactor to make the pressure 0.5 MPa, and then steam was introduced into the jacket of the second jacketed reactor to raise the liquid temperature in the reactor to 150° C., and a clear reaction solution was obtained after reacting for 3 hours;

[0038] 4) The solution obtained in step 3) is stirred at 150 rpm, and circulating cooling water is introduced into the jacket of the second jacketed reactor to reduce the temperature of the liquid in the jacketed reactor to 123°C at a cooling rate of 0.5°C / min, and 556 g of commercially available powdered nylon 10T salt seed is added, and the temperature in the jacketed reactor is further reduced to 110°C at a cooling rate of 0.5°C / min; the temperature in the jacketed reactor is then reduced to 50°C at a cooling rate of 5°C / min, and centrifuged to obtain large particles of nylon 10T salt.

[0039] The product obtained by centrifugation is weighed, the product yield is calculated, and the product particle size distribution is measured. Figure 2 , Table 1.

[0040] The yield and particle size distribution of the products obtained in the above examples are shown in Table 1:

[0041] Table 1

[0042] sample Yield D(10) / μm D(50) / μm D(90) / μm Example 1 99.1％ 466 794 954 Example 2 99.8％ 424 758 915 Example 3 99.6％ 457 776 928 Commercially available nylon 10T salt 19 110 360

[0043] The above examples illustrate that the product obtained by the large-particle nylon 10T salt crystallization method of the present invention has the advantages of large particle size, uniform particle size distribution, high yield, etc., and is suitable for industrial mass production.

[0044] The above is only a specific implementation of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed by the present invention are all within the scope of the technical solution of this patent.

Claims

1. A method for crystallizing large-particle nylon 10T salt, characterized in that The steps include: 1) adding deionized water and decanediamine in a mass ratio of 1.5 to 2:1 to a jacketed reactor replaced with nitrogen or an inert gas under stirring at 100 to 200 rpm, introducing steam into the jacket of the jacketed reactor to raise the temperature of the liquid in the jacketed reactor to 80° C. to 100° C., and obtaining a clear decanediamine aqueous solution; 2) adding deionized water and terephthalic acid in a mass ratio of 3 to 4:1 to the second jacketed reactor replaced with nitrogen or inert gas under stirring at 300 to 400 rpm, introducing steam into the jacket of the second jacketed reactor to raise the temperature of the liquid in the second jacketed reactor to 80° C. to 100° C., and stirring for 60 min to 120 min to obtain a terephthalic acid dispersion; 3) adding the decanediamine aqueous solution to the terephthalic acid dispersion at a rate of 60 mL / min to 120 mL / min under stirring at 300 to 400 rpm, with a molar ratio of decanediamine to terephthalic acid being 1.1 to 1.2:1; After the addition is completed, nitrogen or inert gas is charged into the second jacketed reactor to make the pressure 0.4MPa-0.6MPa, and then steam is introduced into the jacket of the second jacketed reactor to raise the temperature of the liquid in the reactor to 130°C-160°C, and the reaction is carried out for 2-5 hours to obtain a clear reaction solution; 4) The solution obtained in step 3) is stirred at 100 to 200 rpm, and circulating cooling water is introduced into the jacket of the second jacketed reactor to reduce the temperature of the liquid in the jacketed reactor to 120 to 125°C at a cooling rate of 0.3°C / min to 0.8°C / min, and nylon 10T salt seed crystals are added, and the temperature in the jacketed reactor is further reduced to 100 to 119°C at a cooling rate of 0.3°C / min to 0.8°C / min; the temperature in the jacketed reactor is then reduced to 20 to 70°C at a cooling rate of 2°C / min to 5°C / min, and centrifuged to obtain large particles of nylon 10T salt.

2. The crystallization method according to claim 1, characterized in that The inert gas is helium or argon.

3. The crystallization method according to claim 1, characterized in that The added mass of the nylon 10T salt seed crystals is 0.02% of the sum of the mass of decanediamine and terephthalic acid.

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