CN114437343A - Method for synthesizing copolymerized nylon by continuously copolymerizing caprolactam and nylon 66 salt - Google Patents
Method for synthesizing copolymerized nylon by continuously copolymerizing caprolactam and nylon 66 salt Download PDFInfo
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- JBKVHLHDHHXQEQ-UHFFFAOYSA-N epsilon-caprolactam Chemical class O=C1CCCCCN1 JBKVHLHDHHXQEQ-UHFFFAOYSA-N 0.000 title claims abstract description 127
- 239000004677 Nylon Substances 0.000 title claims abstract description 53
- 229920002302 Nylon 6,6 Chemical class 0.000 title claims abstract description 53
- 229920001778 nylon Polymers 0.000 title claims abstract description 53
- 150000003839 salts Chemical class 0.000 title claims abstract description 35
- 238000000034 method Methods 0.000 title claims abstract description 24
- 230000002194 synthesizing effect Effects 0.000 title abstract description 4
- 238000006116 polymerization reaction Methods 0.000 claims abstract description 21
- 238000007334 copolymerization reaction Methods 0.000 claims abstract description 20
- 239000012266 salt solution Substances 0.000 claims abstract description 20
- 239000000178 monomer Substances 0.000 claims abstract description 8
- 238000002156 mixing Methods 0.000 claims abstract description 7
- 238000003756 stirring Methods 0.000 claims abstract description 6
- 239000000203 mixture Substances 0.000 claims abstract 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 12
- 230000008569 process Effects 0.000 claims description 7
- 239000002994 raw material Substances 0.000 claims description 5
- 230000014759 maintenance of location Effects 0.000 claims description 4
- 230000007547 defect Effects 0.000 abstract description 2
- 239000000463 material Substances 0.000 description 57
- 238000000605 extraction Methods 0.000 description 23
- 238000001035 drying Methods 0.000 description 22
- 238000002844 melting Methods 0.000 description 15
- 230000008018 melting Effects 0.000 description 15
- 238000001816 cooling Methods 0.000 description 14
- 239000000155 melt Substances 0.000 description 14
- 239000000047 product Substances 0.000 description 12
- 238000006243 chemical reaction Methods 0.000 description 9
- 238000005266 casting Methods 0.000 description 8
- 238000006068 polycondensation reaction Methods 0.000 description 7
- 239000007790 solid phase Substances 0.000 description 7
- 238000007599 discharging Methods 0.000 description 6
- 239000012632 extractable Substances 0.000 description 6
- 238000010096 film blowing Methods 0.000 description 6
- 238000010438 heat treatment Methods 0.000 description 6
- 230000003068 static effect Effects 0.000 description 6
- 238000010992 reflux Methods 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- 229920002292 Nylon 6 Polymers 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 3
- 229920001577 copolymer Polymers 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- 230000002411 adverse Effects 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 239000012467 final product Substances 0.000 description 2
- 239000011259 mixed solution Substances 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 229920000577 Nylon 6/66 Polymers 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 239000012752 auxiliary agent Substances 0.000 description 1
- TZYHIGCKINZLPD-UHFFFAOYSA-N azepan-2-one;hexane-1,6-diamine;hexanedioic acid Chemical compound NCCCCCCN.O=C1CCCCCN1.OC(=O)CCCCC(O)=O TZYHIGCKINZLPD-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 239000004568 cement Substances 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 238000009459 flexible packaging Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 229920006280 packaging film Polymers 0.000 description 1
- 239000012785 packaging film Substances 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000005191 phase separation Methods 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G69/00—Macromolecular compounds obtained by reactions forming a carboxylic amide link in the main chain of the macromolecule
- C08G69/02—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids
- C08G69/36—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids derived from amino acids, polyamines and polycarboxylic acids
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G69/00—Macromolecular compounds obtained by reactions forming a carboxylic amide link in the main chain of the macromolecule
- C08G69/02—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids
- C08G69/04—Preparatory processes
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- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
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- Life Sciences & Earth Sciences (AREA)
- Proteomics, Peptides & Aminoacids (AREA)
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Abstract
The invention discloses a method for continuously copolymerizing and synthesizing copolymerized nylon by caprolactam and nylon 66 salt, which comprises the steps of mixing preheated caprolactam with 70-80 wt% nylon 66 salt solution from a concentration unit, feeding the mixture into a front polymerizer to perform front polymerization under positive pressure and stirring conditions, and feeding the mixture into a rear polymerizer to perform rear polymerization under normal pressure or negative pressure conditions to obtain copolymerized nylon melt; the method avoids the defect of non-uniform copolymerization ratio caused by immiscible two monomers at the initial stage of copolymerization, and can obtain copolymerized nylon with good processability, transparency and flexibility.
Description
Technical Field
The invention relates to a method for synthesizing copolymerized nylon, in particular to a method for obtaining copolymerized nylon by continuously copolymerizing molten caprolactam and a nylon 66 salt solution, belonging to the technical field of nylon synthesis.
Background
The crystallinity of the copolymerized nylon is lower than that of nylon 6, the transparency, the flexibility and the like of the product are superior to those of the nylon 6, and the copolymerized nylon has advantages in the fields of producing flexible packaging films, high-transparency monofilaments and the like compared with the nylon 6. For reasons of cost and raw material availability, nylon 6/66 copolymer obtained by copolymerizing caprolactam and nylon 66 salt is the most widely used variety.
The continuous polymerization process is the best choice for producing copolymerized nylon in terms of production cost and product stability. However, the nylon 66 salt is not dissolved in caprolactam, and if the two monomers are simply mixed and fed into a continuous polymerization reactor, the nylon 66 salt may be separated from caprolactam, resulting in a partial copolymerization ratio deviating from the batch ratio and a copolymer block having a small amount of excessively high proportion of the nylon 66 salt. The block has low melting point and poor strength, and can generate adverse effect on the overall performance of the copolymerized nylon product.
In the process and apparatus for the continuous preparation of polyamide 6,6 and copolyamides thereof, disclosed in German Polymer company patent DE03810437.7, the process for the continuous copolymerization of caprolactam and nylon 66 salt and for the production of copolymerized nylon is described, which involves a first stage of prepolymerization under pressure, a second stage of a reactor for removing water from the melt of the prepolymer, and a third stage of polymerization under atmospheric or reduced pressure. There is no reference to how to solve the copolymerization homogeneity.
Chinese patent CN 102653591 a describes a process for producing caprolactam and nylon 66 salt copolymer slices, which comprises the following steps: respectively preparing a caprolactam melt, a nylon 66 salt aqueous solution and an additive, pumping the monomers into a mixer for mixing, and then sequentially entering a front polymerization tower and a rear polymerization tower for reaction. The prepared slices are extracted, dried and cooled to obtain the finished product of the caprolactam and nylon 66 salt copolymer slices.
Chinese patent CN 108929436A provides a preparation method of copolymerized nylon, which comprises the following steps: 1) melting caprolactam and storing; 2) dissolving, storing and concentrating salt; 3) preparing an auxiliary agent; 4) continuous polymerization in three steps; 5) cutting the cast strip into particles; 6) extracting; 7) and (5) drying. The invention is mainly characterized in that: the water resource in the preparation process is recycled, no wastewater is discharged, and energy conservation and emission reduction are realized; the melting of the molten caprolactam in the melting tank can be accelerated by mixing the molten caprolactam with the solid caprolactam entering the melting tank, and the melting efficiency is high; the melting of the dissolved 66 salt in the dissolving tank can be accelerated by mixing the dissolved 66 salt with the solid 66 salt entering the dissolving tank, and the dissolving efficiency is high.
The above patents are essentially all directed to the use of nylon 6 polymerization process for the production of copolymerized nylon, and do not address the problem of miscibility of nylon 66 salt with caprolactam and the consequent uneven copolymerization ratios that may result.
Disclosure of Invention
Aiming at the problems that in the prior art, in the continuous copolymerization process of nylon 66 salt and caprolactam, caprolactam and nylon 66 salt are difficult to be uniformly mixed to cause partial copolymerization proportion to deviate from a charge ratio, a small amount of blocks with over-high nylon 66 salt ratio are generated, the melting point of the blocks is low, the strength is poor, and adverse effects can be generated on the overall performance of a copolymerized nylon product, the technical scheme of the invention realizes uniform polymerization of the nylon 66 salt and the caprolactam by uniformly mixing the reinforced nylon 66 salt and the caprolactam, and the copolymerized nylon with good processability, transparency and flexibility is obtained.
In order to realize the technical purpose, the invention provides a method for continuously copolymerizing caprolactam and nylon 66 salt to synthesize copolymerized nylon, which comprises the steps of mixing preheated caprolactam with 70-80 wt% nylon 66 salt solution from a concentration unit, feeding the mixed solution into a pre-polymerizer to perform pre-polymerization under a positive pressure condition, and feeding the mixed solution into a post-polymerizer to perform post-polymerization under a normal pressure or negative pressure condition to obtain copolymerized nylon melt; and the upper part of the front polymerizer is provided with a stirrer for fully stirring the mixed monomer of caprolactam and nylon 66 salt entering the front polymerizer.
As a preferable scheme, the caprolactam is preheated to 160-200 ℃, and is preferably preheated to 180 ℃.
Preferably, the temperature of the nylon 66 salt solution from the concentration unit is 160-180 ℃, and more preferably 180 ℃.
In a preferable mode, the copolymerization ratio of the caprolactam and the nylon 66 salt is 90/10-70/30, and the most preferable ratio is 80/20. If the ratio is too low, copolymerization is not significant, and if the ratio is too high, the chips tend to stick, resulting in poor properties.
As a preferred embodiment, the process of the pre-polymerization is: the mixed raw material consisting of caprolactam and a nylon 66 salt solution enters from the upper part of the front polymerizer and flows towards the lower part of the front polymerizer in a plug flow mode, the residence time of the mixed raw material at the upper part of the front polymerizer is 3-6 hours, and the residence time at the lower part of the front polymerizer is 3-6 hours. In the early stage of polymerization, caprolactam and 66 salt are in a monomer state, and the problem of phase separation exists.
As a preferred embodiment, the conditions of the pre-polymerization are: the temperature is controlled to be 250-275 ℃, the pressure is controlled to be 0.5-1.0 MPa, and the total retention time is 6-12 hours.
As a preferred scheme, the top of the front polymerizer is provided with a packed tower and a condenser for condensing and recovering caprolactam monomer. The escape of caprolactam can be effectively avoided.
As a preferred embodiment, the post-polymerization conditions are: the temperature is controlled to be 250-275 ℃, the pressure is controlled to be 60-101 KPa, and the total retention time is 6-12 hours.
As a preferred scheme, the top of the post-polymerizer is provided with a condenser for condensing and recovering caprolactam monomer and water vapor. The steam generated in the post-polymerization process passes through a condenser, the caprolactam monomer is condensed and refluxed, and the water vapor passes through the condenser and is condensed and recovered in a water vapor condenser.
As a preferred scheme, the copolymerized nylon melt is subjected to belt casting and grain cutting to form slices, and then the slices are subjected to pre-extraction, extraction and drying processes, cooled and packaged to form finished products; or can be subjected to solid-phase polycondensation according to requirements to obtain a product with higher relative viscosity. More specifically, a polymer melt is conveyed to a casting belt and granulated through a melt gear pump from the bottom of a post-polymerizer to form copolymerized nylon chips, then the copolymerized nylon chips sequentially enter a pre-extraction tank and an extraction tower, and the chips are contacted with extraction water from the top of the extraction tower in the extraction tank to carry out pre-extraction; extraction is then carried out in an extraction column with desalted water. The slices run counter-currently with the desalinated water, the slices enter from the top of the column and are discharged from the bottom, the desalinated water enters from the bottom and is discharged from the top. The temperature of the extraction water is 85-100 ℃. And conveying the copolymerized nylon slices to a water separator by using a slice/cement slurry pump, and drying the dehydrated slices in a drying tower by using hot nitrogen. The dried slices can enter a cooling tower, and are packaged into finished products after being cooled. Or entering a solid phase polycondensation tower according to the requirement, carrying out solid phase polycondensation under the heating and blowing of hot nitrogen, further improving the relative viscosity, and then cooling and packaging.
Compared with the prior art, the technical scheme of the invention has the following beneficial technical effects:
the copolymerized nylon prepared by the technical scheme of the invention has good processing property and flexibility, such as tensile strength of 50.24 MPa-54.88 MPa and elongation at break of 288.56-336.98%.
According to the technical scheme, the caprolactam and the nylon 66 salt are mixed under enhanced action, so that the two monomers are polymerized more uniformly, and the defect of non-uniform copolymerization ratio caused by immiscible of the two monomers in the initial copolymerization stage is overcome.
Detailed Description
The present invention will be described in detail with reference to the following embodiments in order to make the aforementioned objects, features and advantages of the invention more comprehensible. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, but rather should be construed as broadly as the present invention is capable of modification in various respects, all without departing from the spirit and scope of the present invention.
Example 1
Caprolactam feeding amount of 40kg/h, heating to 180 ℃ after passing through a preheater, the concentration of the nylon 66 salt solution is 52% wt, the flow rate entering an evaporator is 20kg/h, the concentration is 70% wt after passing through the evaporator, the temperature leaving the evaporator is 180 ℃, and the flow rate is 14.85 kg/h. The copolymerization ratio was about 80/20.
The preheated caprolactam and concentrated nylon 66 salt solution were mixed in a static mixer and fed to a stirred prepolymerizer having an effective volume of 350 liters and a stirred portion of 175 liters. The operation pressure is 0.5MPa, the reaction temperature is 265 ℃, and the reflux of the top condensate is 10 kg/h. The residence time of the material in the pre-polymerizer was about 6 hours.
The material was discharged from the bottom of the pre-polymerizer and transferred to the post-polymerizer via a melt gear pump. The effective volume of the post-polymerizer is 800 liters, the operating pressure is 80KPa (absolute pressure), the temperature of the upper material is 265 ℃, the temperature of the middle material is 260 ℃, and the temperature of the lower material is 255 ℃.
Discharging the material from the bottom of the post-polymerizer, conveying the material by a melt gear pump, casting a belt, granulating the material, then entering a pre-extraction tank, an extraction tower and a drying tower, drying the material at the temperature of 135 ℃, leaving the drying tower, entering a cooling tower, and cooling the material to obtain the finished product of the copolymerized nylon. Relative viscosity 3.16, extractables content 0.42%.
Randomly selecting 5 samples, and determining the melting point of the copolymerized nylon:
the copolymerized nylon chips were blown into a film by a laboratory film blowing machine, and the tensile strength was measured to be 54.88MPa and the elongation at break was measured to be 336.98%.
Comparative example 1
Caprolactam feeding amount of 40kg/h, heating to 180 ℃ after passing through a preheater, the concentration of the nylon 66 salt solution is 52% wt, the flow rate entering an evaporator is 20kg/h, the concentration is 70% wt after passing through the evaporator, the temperature leaving the evaporator is 180 ℃, and the flow rate is 14.85 kg/h. The copolymerization ratio was about 80/20.
The preheated caprolactam and the concentrated nylon 66 salt solution are mixed by a static mixer and enter a pre-polymerizer without stirring, the effective volume of the pre-polymerizer is 350 liters, the operating pressure is 0.5MPa, the reaction temperature is 265 ℃, and the top condensate liquid flows back for 10 kg/h. The residence time of the material in the pre-polymerizer was about 6 hours.
The material was discharged from the bottom of the pre-polymerizer and transferred to the post-polymerizer via a melt gear pump. The effective volume of the post-polymerizer is 800 liters, the operating pressure is 80KPa (absolute pressure), the temperature of the upper material is 265 ℃, the temperature of the middle material is 260 ℃, and the temperature of the lower material is 255 ℃.
Discharging the material from the bottom of the post-polymerizer, conveying the material by a melt gear pump, casting a belt, granulating the material, and then feeding the material into a pre-extraction tank, an extraction tower and a drying tower, wherein the drying temperature is 135 ℃. Leaving the drying tower to enter a cooling tower, and cooling to obtain a copolymerized nylon finished product. Relative viscosity 3.18, extractables content 0.38%.
Randomly selecting 5 samples, and determining the melting point of the copolymerized nylon:
the copolymerized nylon chips were blown into a film by a laboratory film blowing machine, and the tensile strength was measured to be 48.36MPa and the elongation at break was measured to be 247.28%.
Example 2
Caprolactam feeding amount of 40kg/h, heating to 180 ℃ after passing through a preheater, the concentration of the nylon 66 salt solution is 52% wt, entering an evaporator with flow rate of 15kg/h, concentrating to 70% wt through the evaporator, leaving the evaporator with temperature of 180 ℃ and flow rate of 11.1 kg/h. The copolymerization ratio was about 84/16.
The preheated caprolactam and concentrated nylon 66 salt solution were mixed in a static mixer and fed to a stirred prepolymerizer having an effective volume of 350 liters and a stirred portion of 175 liters. The operation pressure is 0.5MPa, the reaction temperature is 265 ℃, and the reflux of the top condensate is 10 kg/h. The residence time of the material in the pre-polymerizer was about 7.3 hours.
The material is discharged from the bottom of the front polymerizer and conveyed to the rear polymerizer through the melt gear pump. The effective volume of the post-polymerizer is 800 liters, the operating pressure is 90KPa (absolute pressure), the temperature of the upper material is 265 ℃, the temperature of the middle material is 260 ℃, and the temperature of the lower material is 255 ℃.
Discharging the material from the bottom of the post-polymerizer, conveying the material by a melt gear pump, casting a belt, granulating the material, then entering a pre-extraction tank, an extraction tower and a drying tower, drying the material at the temperature of 135 ℃, leaving the drying tower, entering a cooling tower, and cooling the material to obtain the finished product of the copolymerized nylon. Relative viscosity 2.87, extractables content 0.35%.
Randomly selecting 5 samples, and determining the melting point of the copolymerized nylon:
the copolymerized nylon chips were blown into a film by a laboratory film blowing machine, and the tensile strength was measured to be 50.24MPa and the elongation at break was measured to be 288.56%.
Comparative example 2
The feeding amount of caprolactam is 40kg/h, the caprolactam is heated to 180 ℃ after passing through a preheater, the concentration of a nylon 66 salt solution is 52% by weight, the flow rate of the caprolactam entering an evaporator is 15kg/h, the caprolactam is concentrated to 70% by weight through the evaporator, the temperature of the caprolactam leaving the evaporator is 180 ℃, and the flow rate of the caprolactam is 11.1 kg/h. The copolymerization ratio was about 84/16.
The preheated caprolactam and the concentrated nylon 66 salt solution are mixed by a static mixer and enter a non-stirring pre-polymerizer, and the effective volume of the pre-polymerizer is 350 liters. The operation pressure is 0.5MPa, the reaction temperature is 265 ℃, and the reflux of the top condensate is 10 kg/h. The residence time of the material in the pre-polymerizer was about 7.3 hours.
The material was discharged from the bottom of the pre-polymerizer and transferred to the post-polymerizer via a melt gear pump. The effective volume of the post-polymerizer is 800 liters, the operating pressure is 90KPa (absolute pressure), the temperature of the upper material is 265 ℃, the temperature of the middle material is 260 ℃, and the temperature of the lower material is 255 ℃.
Discharging the material from the bottom of the post-polymerizer, conveying the material by a melt gear pump, casting a belt, granulating the material, then entering a pre-extraction tank, an extraction tower and a drying tower, drying the material at the temperature of 135 ℃, leaving the drying tower, entering a cooling tower, and cooling the material to obtain the finished product of the copolymerized nylon. Relative viscosity 2.72, extractables content 0.32%.
Randomly selecting 5 samples, and determining the melting point of the copolymerized nylon:
the copolymerized nylon chips were blown into films by means of a laboratory film blowing machine, and the tensile strength and elongation at break were determined to be 55.78MPa and 186.23%.
Example 3
Caprolactam feeding amount of 40kg/h, heating to 180 ℃ after passing through a preheater, the concentration of the nylon 66 salt solution is 52% wt, the flow rate entering an evaporator is 20kg/h, the concentration is 70% wt after passing through the evaporator, the temperature leaving the evaporator is 180 ℃, and the flow rate is 14.85 kg/h. The copolymerization ratio was about 80/20.
The preheated caprolactam and concentrated nylon 66 salt solution were mixed in a static mixer and fed to a stirred prepolymerizer having an effective volume of 350 liters and a stirred portion of 175 liters. The operation pressure is 0.5MPa, the reaction temperature is 265 ℃, and the reflux of the top condensate is 10 kg/h. The residence time of the material in the pre-polymerizer was about 6 hours.
The material was discharged from the bottom of the pre-polymerizer and transferred to the post-polymerizer via a melt gear pump. The effective volume of the post-polymerizer is 800 liters, the operating pressure is 80KPa (absolute pressure), the temperature of the upper material is 265 ℃, the temperature of the middle material is 260 ℃, and the temperature of the lower material is 255 ℃.
Discharging the material from the bottom of the post-polymerizer, conveying the material by a melt gear pump, casting a belt, granulating the material, and then feeding the material into a pre-extraction tank, an extraction tower and a drying tower, wherein the drying temperature is 135 ℃. Leaving the drying tower to enter a solid phase polycondensation tower for solid phase polycondensation reaction at the reaction temperature of 160 ℃ for 32 hours, then entering a cooling tower for cooling to obtain the final product of the copolymerized nylon. Relative viscosity 4.12, extractables content 0.56%.
Randomly selecting 5 samples, and determining the melting point of the copolymerized nylon:
the copolymerized nylon slice is blown into a film by a laboratory film blowing machine, the measured tensile strength is 60.65MPa, and the elongation at break is 405.76 percent
Comparative example 3
Caprolactam feeding amount of 40kg/h, heating to 180 ℃ after passing through a preheater, the concentration of the nylon 66 salt solution is 52% wt, the flow rate entering an evaporator is 20kg/h, the concentration is 70% wt after passing through the evaporator, the temperature leaving the evaporator is 180 ℃, and the flow rate is 14.85 kg/h. The copolymerization ratio was about 80/20.
The preheated caprolactam and the concentrated nylon 66 salt solution are mixed by a static mixer and enter a non-stirring pre-polymerizer, and the effective volume of the pre-polymerizer is 350 liters. The operation pressure is 0.5MPa, the reaction temperature is 265 ℃, and the reflux of the top condensate is 10 kg/h. The residence time of the material in the pre-polymerizer was about 6 hours.
The material was discharged from the bottom of the pre-polymerizer and transferred to the post-polymerizer via a melt gear pump. The effective volume of the post-polymerizer is 800 liters, the operating pressure is 80KPa (absolute pressure), the temperature of the upper material is 265 ℃, the temperature of the middle material is 260 ℃, and the temperature of the lower material is 255 ℃.
Discharging the material from the bottom of the post-polymerizer, conveying the material by a melt gear pump, casting a belt, granulating the material, and then feeding the material into a pre-extraction tank, an extraction tower and a drying tower, wherein the drying temperature is 135 ℃. Leaving the drying tower to enter a solid phase polycondensation tower for solid phase polycondensation reaction at the reaction temperature of 160 ℃ for 32 hours, then entering a cooling tower for cooling to obtain the final product of the copolymerized nylon. Relative viscosity 4.06, extractables content 0.63%.
Randomly selecting 5 samples, and determining the melting point of the copolymerized nylon:
the copolymerized nylon slice is blown into a film by a laboratory film blowing machine, and the measured tensile strength is 57.25MPa, the elongation at break is 315.02 percent
The melting point fluctuation range of the copolymerized nylon produced by the process is smaller, and the copolymerization proportion is relatively uniform. The prepared film also has better strength and stretchability.
Claims (9)
1. A method for continuously copolymerizing caprolactam and nylon 66 salt to synthesize copolymerized nylon is characterized in that: mixing preheated caprolactam with a nylon 66 salt solution with the concentration of 70-80 wt% from a concentration unit, then feeding the mixture into a front polymerizer to perform front polymerization under a positive pressure condition, and then feeding the mixture into a rear polymerizer to perform rear polymerization under a normal pressure or negative pressure condition to obtain a copolymerized nylon melt; and the upper part of the front polymerizer is provided with a stirrer for fully stirring the mixed monomer of caprolactam and nylon 66 salt entering the front polymerizer.
2. The method for continuously copolymerizing caprolactam and nylon 66 salt to obtain the copolymerized nylon according to claim 1, wherein: and preheating the caprolactam to 160-200 ℃.
3. The method for continuously copolymerizing caprolactam and nylon 66 salt to obtain the copolymerized nylon according to claim 1, wherein: the temperature of the nylon 66 salt solution from the concentration unit is 160-180 ℃.
4. The method for continuously copolymerizing caprolactam and nylon 66 salt into copolymerized nylon according to any one of claims 1 to 3, wherein the method comprises the following steps: the copolymerization ratio of the caprolactam and the nylon 66 salt is 90/10-70/30.
5. The method for continuously copolymerizing caprolactam and nylon 66 salt to obtain the copolymerized nylon according to claim 1, wherein: the process of the pre-polymerization is as follows: the mixed raw material consisting of caprolactam and a nylon 66 salt solution enters from the upper part of the front polymerizer and flows towards the lower part of the front polymerizer in a plug flow mode, the residence time of the mixed raw material at the upper part of the front polymerizer is 3-6 hours, and the residence time at the lower part of the front polymerizer is 3-6 hours.
6. The method for continuously copolymerizing caprolactam and nylon 66 salt to obtain the copolymerized nylon according to claim 5, wherein: the conditions of the pre-polymerization are as follows: the temperature is controlled to be 250-275 ℃, the pressure is controlled to be 0.5-1.0 MPa, and the total retention time is 6-12 hours.
7. The method for continuously copolymerizing caprolactam and nylon 66 salt to obtain the copolymerized nylon according to claim 1, wherein: the top of the front polymerizer is provided with a packed tower and a condenser for condensing and recovering caprolactam monomer.
8. The method for continuously copolymerizing caprolactam and nylon 66 salt to obtain the copolymerized nylon according to claim 1, wherein: the conditions of the postpolymerization are as follows: the temperature is controlled to be 250-275 ℃, the pressure is controlled to be 60-101 KPa, and the total retention time is 6-12 hours.
9. The method for continuously copolymerizing caprolactam and nylon 66 salt to obtain the copolymerized nylon according to claim 1, wherein: the top of the post-polymerizer is provided with a condenser for condensing and recovering caprolactam monomer and water vapor.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011107622.6A CN114437343A (en) | 2020-10-16 | 2020-10-16 | Method for synthesizing copolymerized nylon by continuously copolymerizing caprolactam and nylon 66 salt |
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