A continuous polymerization process for gel-resistant copolyamide 56 / 6 and gel-resistant copolyamide 56 / 6

Abstract

The application discloses a continuous polymerization method of anti-gel copolyamide 56 / 6 and the anti-gel copolyamide 56 / 6, and the continuous polymerization method comprises the following steps: preparing a water solution of polyamide 56 salt by using bio-based pentanediamine and adipic acid, mixing with caprolactam and / or a prepolymer thereof, conveying to a first-stage reactor, pre-polymerizing under normal pressure to form a prepolymer, conveying to a tubular programmed temperature device for programmed temperature and pressure maintaining, then conveying to a second-stage reactor for post-polymerization reaction, obtaining a copolyamide 56 / 6 melt, and finally cooling, granulating and drying to obtain the anti-gel copolyamide 56 / 6. The polymerization process of normal pressure pre-polymerization combined with programmed temperature can reduce the cost of polymerization equipment, effectively inhibit the side reaction of pentanediamine monomer decomposition and volatilization in the preparation process, reduce the melting point through copolymerization, thereby the spinning temperature of the obtained copolymer for spinning can be reduced, the gelation in the spinning process is reduced, the melt stability of the copolymer is enhanced, and the application in the spinning field is met.

Description

Technical Field

[0001] This invention belongs to the field of bio-based polyamide materials, specifically, it relates to a continuous polymerization method for anti-gelling copolyamide 56 / 6 and the anti-gelling copolyamide 56 / 6. Background Technology

[0002] Polyamide (PA), commonly known as nylon, is a general term for thermoplastic resins containing repeating amide groups -CONH- in the main molecular chain. It is a widely used high molecular polymer material with excellent physical and chemical properties. Its fiber production is second only to polyester fiber, making it the second largest synthetic fiber raw material and ranking first among the five major engineering plastics.

[0003] Bio-based polyamide 56 (PA56) is a potential advanced basic material, polymerized from bio-based pentanediamine and petroleum-based adipic acid. PA56 has a similar structure to PA66, and its strength and specific gravity are comparable to PA66 in the polyamide family. Bio-based PA56 fibers have better dyeability, moisture absorption and quick-drying properties, and flame retardancy than PA66 fibers. Moreover, due to its good softness, elasticity, and abrasion resistance, it can be blended with cotton and linen to weave T-shirts, elastic underwear, life jackets, carpets, tents, etc., making it a very competitive bio-based polyamide material.

[0004] During the development of PA56, it was discovered that the polymerization of PA56 is prone to side reactions involving the decomposition and volatilization of pentanediamine monomer. Traditional polymerization processes suppress pentanediamine volatilization through high pressure, but this requires sophisticated equipment. In the high-temperature molten state, PA56 generates cyclopentanone during the polymerization process. Cyclopentanone is a crosslinking agent for a specific substance; its presence crosslinks macromolecular chains, thus producing gels, which has a certain impact on downstream applications.

[0005] To address the issue of pentanediamine monomer decomposition and volatilization, Chinese Patent Application No. 201310049401.1 discloses a method for preparing nylon. This method utilizes the inherent properties of pentanediamine nylon salt, employing high concentrations to effectively suppress pentanediamine volatilization. However, maintaining a high concentration of nylon salt solution before the polymerization reaction to prevent acid-amine imbalance caused by 1,5-pentanediamine volatilization necessitates the addition of concentration equipment. This equipment requires regular maintenance, consuming significant manpower and resources, and increasing production costs.

[0006] Chinese patent application number 201310074772.5 discloses a method for manufacturing nylon. This method involves preparing a nylon salt aqueous solution from a diamine and a diacid, then adjusting the pH of the solution to a specific value using the diamine. Additional diamine is added to compensate for the loss of pentanediamine during the polymerization process in side reactions. However, to obtain nylon with a high viscosity, this method requires the addition of extra diamine, resulting in both raw material loss and air pollution. Capturing the pentanediamine in a cooling tower to prevent air pollution would further increase costs.

[0007] Bio-based PA56 is prone to gelation at temperatures above 275°C. Gel formation increases the polymer's molecular weight, broadens its molecular weight distribution, and reduces melt stability, significantly impacting its applications in spinning and engineering plastics. Therefore, to ensure melt stability and product quality, processing temperatures should not exceed 275°C. However, PA56's melting point is around 256°C. Processing temperatures below 275°C cannot guarantee good flowability; further temperature increases will lead to gelation. The gel has poor flowability and solubility, easily adhering to equipment, clogging pipes and spinning components, and damaging downstream equipment. This necessitates substantial manpower and resources for gel removal and equipment maintenance.

[0008] In view of this, the present invention is hereby proposed. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art. On the one hand, the present invention provides a continuous polymerization method for anti-gelling copolyamide 56 / 6, which can reduce the cost of polymerization equipment and effectively reduce melt gelation.

[0010] In another aspect, the present invention provides an antigel copolyamide 56 / 6 prepared by the above-described continuous polymerization method.

[0011] To solve the above-mentioned technical problems, the basic concept of the technical solution adopted by the present invention is as follows:

[0012] The first aspect of this invention provides a continuous polymerization method for anti-gelling copolyamide 56 / 6, comprising the following steps:

[0013] 1) Prepare an aqueous solution of polyamide 56 salt using bio-based pentanediamine and adipic acid;

[0014] 2) Mix the aqueous solution of polyamide 56 salt obtained in step 1) with the copolymer component, wherein the copolymer component is caprolactam and / or its prepolymer;

[0015] 3) The mixture from step 2) is fed to the first stage reactor and prepolymerized under normal pressure to form a prepolymer;

[0016] 4) The prepolymer obtained in step 3) is transported to a tubular temperature-programmed heating device for programmed heating and pressure holding;

[0017] 5) The material in step 4) is transported to the second stage reactor by the tubular programmed temperature rise device to carry out the post-polymerization reaction and obtain copolyamide 56 / 6 melt;

[0018] 6) The copolyamide 56 / 6 melt obtained in step 5) is cooled, pelletized, and dried to obtain antigel copolyamide 56 / 6.

[0019] In one specific implementation, in step 6), the copolyamide 56 / 6 melt is cooled, granulated, extracted, and then dried to obtain the final product.

[0020] In this invention, a two-stage continuous polymerization process is employed. The first stage reactor is an atmospheric pressure prepolymerization unit, and the second stage reactor is a post-polymerization unit. A tubular programmed temperature riser is added to the conveying pipeline between the two to achieve programmed temperature rise and pressure maintenance of the materials. Compared with the high-pressure polymerization process in the prior art, this invention uses an atmospheric pressure prepolymerization combined with programmed temperature rise polymerization, which reduces the cost of polymerization equipment and can effectively suppress the decomposition and volatilization side reactions of pentanediamine monomer.

[0021] On the other hand, introducing caprolactam into the PA56 chain segment to achieve copolymerization lowers the melting point of the copolymer, thereby reducing the polymerization temperature and minimizing melt gelation. The introduction of caprolactam also ensures strength, improves toughness, and allows the resulting copolymer to be used at spinning temperatures below 275°C, achieving excellent anti-gelation effects and reducing gelation during the spinning process, making it suitable for applications in the spinning field.

[0022] In a further step, step 3), the prepolymerization temperature is 135–165°C, and the drainage is maintained at normal pressure.

[0023] In step 4), the material temperature in the pipeline outlet area of ​​the tubular temperature program device is 190-230℃, and the pressure is maintained at 0.2-0.3MPa;

[0024] In step 5), the temperature of the post-polymerization reaction is 235-275℃, the pressure is maintained at 0.2-0.3MPa, and after the reaction is completed, a vacuum is drawn and the mixture is allowed to stand to obtain the copolyamide 56 / 6 melt.

[0025] All pressures mentioned are gauge pressures;

[0026] Preferably, in step 3), after the prepolymerization begins, the material temperature in the reaction system is 155–165°C, and the residence time is 2–4 hours.

[0027] Preferably, in step 4), the material temperature in the pipeline outlet area is 195–230°C, and the residence time is 20–40 min;

[0028] Preferably, in step 5), the material temperature in the post-polymerization reaction system is 235–275°C, and the residence time is 2–4 h.

[0029] In the present invention, "programmed heating" refers to the process by which material is gradually or progressively heated as it flows through a tubular programmed heating device. The residence time of the material in the tubular programmed heating device refers to the time elapsed from when the material enters the tubular programmed heating device to when it flows out of the device.

[0030] The melting point of bio-based PA56 is 252–256°C, while the boiling point of bio-based pentanediamine monomer is 178°C. During the polymerization process using PA56 salt as a raw material, the salt undergoes a pentanediamine decomposition side reaction at high temperatures and is lost with the evaporation of water vapor, ultimately leading to an imbalance in the ratio of pentanediamine to adipic acid. The same pentanediamine loss problem exists in the copolymerization of PA56 as the main component, resulting in a lower polymer molecular weight and large fluctuations in the relative viscosity of the product. In the present invention, the material is prepolymerized under normal pressure, then subjected to programmed temperature increase and pressure holding, and finally undergoes a post-polymerization reaction. This avoids the use of existing high-pressure polymerization processes, reducing polymerization equipment costs and effectively suppressing the pentanediamine monomer decomposition and volatilization side reaction, resulting in controllable molecular weight of the polymerized resin chips.

[0031] Gel formation is a common phenomenon in the processing of most thermoplastic resins. PA56 chips easily form cyclopentanone during high-temperature melting at 275℃ and above. Cyclopentanone, as a specific crosslinking agent, crosslinks macromolecular chains, resulting in a three-dimensional polymer that is difficult to melt upon reheating, forming a gel. This gel formation significantly impacts downstream spinning applications. On one hand, it can damage spinning equipment; on the other hand, it increases the molecular weight of the chips, broadens the molecular weight distribution, and makes the relative viscosity unstable. This leads to increased breakage rates and decreased spinnability during spinning, and also causes unstable end groups in the chips, resulting in uneven dyeing of the finished product. The solution of this invention addresses the gel problem by using copolymerization to lower the melting point. The polymer temperature can be kept below 275℃, enhancing the melt stability of the copolymer, improving product quality, and solving the coloring problem, thus meeting the application requirements of polyamide 56 copolymer in the spinning field.

[0032] In a further step, the vacuuming time in step 5) is 1–3 minutes;

[0033] Preferably, the vacuum level during evacuation is controlled to be -0.01 to -0.03 MPa;

[0034] Preferably, the material is stirred while vacuuming, and the stirring speed is 5 to 60 rpm, preferably 10 to 50 rpm;

[0035] Preferably, the settling time is 5 to 30 minutes, and more preferably 10 to 15 minutes.

[0036] In a further embodiment, in step 4), the tubular programmed temperature rise device includes at least two horizontal reactors connected in sequence, and the prepolymer passes through the cavities of each horizontal reactor in sequence.

[0037] Preferably, the horizontal reactor is provided with a helical propeller inside its cavity, and the rotation of the helical propeller causes the prepolymer to flow from one end to the other within the cavity of the horizontal reactor.

[0038] In the above scheme, the tubular temperature program device includes two or more horizontal reactors arranged in series. The prepolymer flows from one end to the other in the cavity of the horizontal heating unit, thereby gradually or stepwise heating up. After passing through two or more horizontal reactors in sequence, it reaches the required temperature range and can then enter the second reactor for post-polymerization reaction.

[0039] The screw propeller helps control the material to flow through the chambers of each horizontal reactor at a basically uniform speed, enhances the uniformity of the material passing through the tubular programmed heating device, and avoids the problem of some materials flowing too fast while others remain in the tubular programmed heating device for a long time.

[0040] In a further embodiment, in step 2), the added mass of the copolymer component is 5 wt% to 40 wt% of the total mass of the bio-based pentanediamine, adipic acid, and copolymer component, with a preferred mass percentage of 5 wt% to 30 wt% and a more preferred mass percentage of 10 wt% to 20 wt%.

[0041] As one specific implementation method, caprolactam can be added directly to the aqueous solution of PA56 salt.

[0042] As another specific implementation method, caprolactam can be first ring-opened to generate a prepolymer, and then the caprolactam prepolymer can be added to an aqueous solution of PA56 salt.

[0043] In one specific embodiment, an aqueous solution of PA56 salt and caprolactam (or a prepolymer of caprolactam) are separately fed into a mixer, where they are thoroughly mixed before being conveyed to the first stage reactor.

[0044] The addition of caprolactam or its prepolymer as a copolymer can lower the melting point of the copolymer. As its proportion increases, the melting point gradually decreases, and its anti-gel properties gradually improve. However, experiments have shown that excessive addition of caprolactam leads to a significant drop in the melting point, and an excessively low melting point results in poor thermal stability of the material. In particular, when the proportion of the copolymer reaches 60 wt%, the melting point and thermal decomposition temperature of the copolymer decrease significantly. When using boiling water to extract the oligomers, the chips melt, which is detrimental to downstream applications.

[0045] In this invention, PA56 dominates the copolymer, while a small amount of caprolactam is distributed within the copolymer to achieve better performance. Specifically, when the proportion of the copolymer component added is 5wt% to 40wt%, the resulting copolymer has sufficient anti-gelling properties while having minimal impact on other properties. When the proportion of the copolymer component added is controlled between 5wt% and 30wt%, and more preferably between 10wt% and 20wt%, the resulting copolymer chips exhibit better spinnability in the spinning field.

[0046] In a further embodiment, in step 1), the molar ratio of bio-based pentanediamine to adipic acid is (1.00–1.05):1, preferably (1.02–1.05):1.

[0047] The theoretical molar ratio of bio-based pentanediamine to adipic acid should be 1:1. Considering that pentanediamine has a low boiling point, it is difficult to control its complete non-volatile nature during the actual polymerization process. Therefore, when preparing PA56 salt, it is preferable to add a small amount of pentanediamine to make the aqueous solution of PA56 salt alkaline.

[0048] In a preferred embodiment, the temperature for preparing polyamide 56 salt is 40–70°C, preferably 55–65°C;

[0049] In a preferred embodiment, the concentration of the aqueous solution of the polyamide 56 salt is 50 wt% to 70 wt%, preferably 55 wt% to 70 wt%. Within this concentration range, the aqueous solution of the polyamide 56 salt is more uniform.

[0050] In one specific embodiment, water, bio-based pentanediamine, and adipic acid are added to an enamel-lined salt-forming kettle to prepare an aqueous solution of polyamide 56 salt. The solvent used can be deionized water, deoxygenated water, or a combination of both, with deionized water being preferred.

[0051] More specifically, deionized water is added to an enamel-lined salt-forming vessel, and then bio-based pentanediamine and adipic acid are added in a molar ratio of approximately 1:1. A small amount of bio-based pentanediamine is then added to adjust the pH value. After that, a vacuum is drawn, and nitrogen is introduced to replace the air in the vessel. After replacing the air three times, the vessel is protected with nitrogen and stirred to form salt, thus obtaining an aqueous solution of PA56 salt.

[0052] A further approach involves adding an additive during the preparation process at a concentration not exceeding 4 wt% of the total copolymer content.

[0053] Preferably, the amount of the additive added is no more than 2 wt% of the total amount of the copolymer.

[0054] In the above scheme, it is equivalent to the total mass percentage of polyamide 56 salt and copolymer components in the copolymer being 96% or more, preferably 98% or more.

[0055] In this invention, various conventional polyamide additives can be added to further improve the performance of the copolymer product.

[0056] In a further embodiment, the additives include, but are not limited to, any one or more combinations of: stabilizers, end-capping agents, catalysts, antioxidants, flame retardants, matting agents, weathering agents, gloss enhancers, dyes, crystal nucleating agents, UV stabilizers, plasticizers, and antistatic agents.

[0057] As one specific embodiment, the stabilizer includes, but is not limited to, any one or more combinations of: di(2,2,6,6-tetramethyl-3-piperidinamido)-isophthalamide (also known as SEED), 4-amino-2,2,6,6-tetramethylpiperidine, N-(5-(1,1)dimethylethyl)-2-ethoxyphenyl)-N'-(2-ethylphenyl)ethylenediamide and N-(2-ethoxyphenyl)-N'-(4-ethylphenyl)ethylenediamide.

[0058] The stabilizer is preferably bis(2,2,6,6-tetramethyl-3-piperidinamido)-isophthalamide or 4-amino-2,2,6,6-tetramethylpiperidine.

[0059] As one specific embodiment, the capping agent includes, but is not limited to, any one or a combination of hexamethylenediamine, decanediamine, m-phenylenediamine, adipic acid, and sebacic acid.

[0060] The capping agent preferably includes one or more combinations of hexamethylenediamine, decanediamine, and m-phenylenediamine.

[0061] As one specific embodiment, the weathering agent includes, but is not limited to: resorcinol, hindered amine, benzotriazole, benzophenone, and salicylates.

[0062] As one specific embodiment, the pigments include, but are not limited to, carbon black, cadmium sulfide, and phthalocyanine.

[0063] As one specific embodiment, the gloss enhancer includes, but is not limited to, calcium carbonate and titanium dioxide.

[0064] In one specific embodiment, the dyes include, but are not limited to, aniline black and nigger black.

[0065] In one specific embodiment, the crystal nucleating agent includes, but is not limited to, kaolin, talc, clay, and silicon dioxide.

[0066] In one specific embodiment, the plasticizer includes, but is not limited to, p-N-butylbenzenesulfonamide and octyl oxybenzoate.

[0067] As one specific implementation, the antistatic agent includes, but is not limited to: betaine-based amphoteric antistatic agents, alkyl sulfate-type anionic antioxidants, nonionic antistatic agents, and quaternary ammonium salt-type cationic antistatic agents.

[0068] As one specific embodiment, the flame retardant includes, but is not limited to: halogenated flame retardants (brominated epoxy resin, etc.), nitrogen-based flame retardants (melamine cyanurate, etc.), phosphorus-based flame retardants (3-hydroxyphenylphosphopropionic acid, ammonium polyphosphate, etc.).

[0069] As one specific embodiment, the catalyst includes, but is not limited to, hypophosphite, phosphate, hypophosphite, etc.

[0070] As one specific embodiment, the matting agent includes, but is not limited to, titanium dioxide.

[0071] In a preferred embodiment, the additives used include stabilizers and end-capping agents.

[0072] In this invention, the additive can be added at different times, such as during the salt formation stage, the prepolymerization stage, or the post-polymerization stage.

[0073] As one specific implementation method, the capping agent can be added during the prepolymerization stage or during the programmed temperature rise stage.

[0074] In one specific implementation, the additive can be added directly; or it can be prepared into a solution and then added in solution form.

[0075] In one specific embodiment of the present invention, the continuous polymerization method of the anti-gelling copolyamide 56 / 6 includes the following steps:

[0076] 1) Add deionized water, bio-based pentanediamine and adipic acid to an enamel-lined salt-forming kettle, then use a small amount of bio-based pentanediamine to adjust the pH value, evacuate the kettle, and then fill it with nitrogen to replace the air in the kettle. After replacing the air three times, protect it with nitrogen and stir to form salt, thus obtaining an aqueous solution of polyamide 56 salt.

[0077] 2) Add caprolactam to the salt solution obtained in step 1);

[0078] 3) Add the mixed solution prepared in step 2) into the first stage reactor, replace the air with nitrogen, heat with heat transfer oil and turn on the stirrer, slowly raise the temperature of the mixed solution, maintain normal pressure and exhaust state, react for 2 to 4 hours, the material temperature in the reaction system is 135 to 165℃, and the prepolymer is obtained.

[0079] 4) The prepolymer is transported to a tubular programmed temperature riser for programmed temperature rise and pressure is maintained at 0.2-0.3 MPa (gauge pressure) for 20-40 minutes. The material temperature in the pipeline outlet area is 190-230℃.

[0080] 5) The material is conveyed to the second stage reactor. The temperature of the material in the reaction system is 235-275℃. The mixture is continuously stirred and the pressure is maintained at 0.2-0.3MPa (gauge pressure). After reacting for 2-3 hours, a vacuum is drawn and the vacuum degree is controlled at -0.01--0.03MPa (gauge pressure). The vacuuming time is 1-3 minutes. Then the stirring is stopped and the mixture is allowed to stand for 5-30 minutes to obtain the copolyamide 56 / 6 melt.

[0081] 6) After polymerization, the material is melted and discharged. After cooling, it is granulated by a pelletizer and dried under vacuum at 100°C to obtain antigel copolyamide 56 / 6.

[0082] In a further embodiment, additives are added in step 2) above.

[0083] The second aspect of the present invention provides an antigel copolyamide 56 / 6, which is prepared by the continuous polymerization method of the antigel copolyamide 56 / 6 provided in the first aspect of the present invention.

[0084] In a further embodiment, the antigel copolyamide 56 / 6 has a relative viscosity of 2.60–3.00 and a melting point of 195–250°C.

[0085] In this invention, the obtained antigel copolyamide 56 / 6 (PA56 / 6) contains caprolactam segments and polyamide 56 salt segments, wherein the mass percentage of the caprolactam segments in the copolymer is 5wt% to 40wt%, preferably 10wt% to 20wt%.

[0086] The polyamide 56 salt segment further includes -NH(CH2)5NH- segment and -CO(CH2)4CO- segment, wherein the molar ratio of -NH(CH2)5NH- segment to -CO(CH2)4CO- segment is (1.00~1.05):1, preferably (1.02~1.05):1.

[0087] By adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art.

[0088] 1. This invention employs a two-stage continuous polymerization device. The first stage is an atmospheric pressure prepolymerization device, and the second stage is a postpolymerization device. An intermediate conveying pipeline is equipped with a device that enables continuous material conveying and programmed temperature rise while maintaining pressure, thus achieving continuous copolymer production. Compared with the existing high-pressure polymerization process, the use of atmospheric pressure prepolymerization combined with programmed temperature rise polymerization process reduces the cost of polymerization equipment. Furthermore, this polymerization process can effectively suppress the decomposition and volatilization side reactions of pentanediamine monomer.

[0089] 2. By lowering the melting point through copolymerization, the polymerization temperature is kept below 275℃. At the same time, the spinning temperature during spinning can also be kept below 275℃, which greatly reduces melt gelation, enhances the melt stability of the copolymer, improves product quality, solves the coloring problem, and can meet the application requirements of polyamide 56 copolymer in the spinning field.

[0090] The specific embodiments of the present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0091] The accompanying drawings, as part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention, but do not constitute an undue limitation of the invention. Obviously, the drawings described below are merely some embodiments, and those skilled in the art can obtain other drawings based on these drawings without creative effort. In the drawings:

[0092] Figure 1 This is a schematic diagram of the continuous polymerization apparatus used in this invention.

[0093] In the diagram: 1. Polyamide 56 salt storage tank; 2. Caprolactam storage tank; 3. Static mixer; 41. First transfer pump; 42. Second transfer pump; 43. Third transfer pump; 5. First stage reactor; 51. Prepolymerization drainage device; 6. Second stage reactor; 61. Postpolymerization drainage device; 71. First pressure holding valve; 72. Second pressure holding valve; 73. Third pressure holding valve; 8. Additive storage tank; 9. Tubular programmed temperature rise device; 91. Horizontal reactor; 92. Screw propeller; 11. Pelletizer; 12. Resin silo; 13. Fan.

[0094] It should be noted that these accompanying drawings and textual descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art by referring to specific embodiments. Detailed Implementation

[0095] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0096] In the description of this invention, it should be noted that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0097] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0098] An embodiment of the present invention provides a continuous polymerization method for antigel copolyamide 56 / 6.

[0099] As one specific implementation method, the continuous polymerization method can employ, for example... Figure 1 The continuous polymerization apparatus shown is used to achieve this.

[0100] The continuous polymerization apparatus includes a polyamide 56 salt storage tank 1, a caprolactam storage tank 2, and a static mixer 3. The polyamide 56 salt storage tank 1 and the caprolactam storage tank 2 are respectively connected to the static mixer 3. An aqueous solution of PA56 salt, prepared by mixing bio-based pentanediamine and adipic acid with water, is stored in the polyamide 56 salt storage tank 1. The caprolactam storage tank 2 stores caprolactam and / or the prepolymer formed after caprolactam ring-opening. The aqueous solution of PA56 salt and the caprolactam and / or their prepolymer are respectively introduced into the static mixer 3 for homogeneous mixing.

[0101] Furthermore, downstream of the static mixer 3, the continuous polymerization apparatus sequentially includes a first-stage reactor 5, a tubular programmed temperature riser 9, a second-stage reactor 6, a pelletizer 11, and a resin silo 12. A first transfer pump 41 is provided between the static mixer 3 and the first-stage reactor 5 to feed the mixture in the static mixer 3 into the first-stage reactor 5 for prepolymerization. The top of the first-stage reactor 5 has a prepolymerization drainage device 51 to maintain drainage during the prepolymerization process.

[0102] The prepolymer generated in the first reactor 5 is transported to the downstream tubular temperature-programmed unit 9, where it undergoes programmed heating and pressure maintenance during its flow. In one specific embodiment, the tubular temperature-programmed unit 9 includes at least two horizontal reactors 91 connected in sequence. The prepolymer sequentially passes through the cavities of each horizontal reactor 91 to achieve programmed heating. A first pressure-maintaining valve 71 is installed on the pipeline between the first reactor 5 and the tubular temperature-programmed unit 9, and a second pressure-maintaining valve 72 is installed on the pipeline between the tubular temperature-programmed unit 9 and the second reactor 6. The first and second pressure-maintaining valves 71 cooperate to achieve pressure maintenance during the programmed heating process.

[0103] In a more specific structure, the axis of the horizontal reactor 91 is arranged basically horizontally, and a helical propeller 92 is provided inside its cavity. The rotation of the helical propeller 92 causes the prepolymer to flow from one end to the other within the cavity of the horizontal reactor 91. Specifically, the helical propeller 92 includes a rotating shaft coaxially arranged with the horizontal reactor 91, and helically extending blades are provided on the outer circumference of the rotating shaft. One end of the rotating shaft extends out of the cavity of the horizontal reactor 91 and is connected to a drive motor.

[0104] A second transfer pump 42 is installed between the tubular programmed temperature riser 9 and the second stage reactor 6 to transport materials to the second stage reactor 6 for post-polymerization reaction, obtaining PA56 / 6 melt. The top of the second stage reactor 6 has a post-polymerization drainage device 61 to drain water during the post-polymerization process. A third pressure holding valve 73 is installed between the second stage reactor 6 and the pelletizer 11. The second pressure holding valve 72 and the third pressure holding valve 73 work together to achieve the pressure holding effect of the second stage reactor 6.

[0105] In one specific embodiment, the first reactor 5 and the second reactor 6 are respectively polymerization kettles.

[0106] Furthermore, a third delivery pump 43 is provided downstream of the third pressure holding valve 73 to transport the PA56 / 6 melt synthesized in the second stage reactor 6 to the pelletizer 11. After cooling, the PA56 / 6 melt is granulated in the pelletizer 11 and then sent into the resin silo 12.

[0107] Specifically, the PA56 / 6 melt is cooled in a cold water bath, solidifies into strips, and is then pelletized in a pelletizer 11. The resulting copolymer chips have a high surface moisture content and need to be air-dried or naturally dried to remove surface moisture before vacuum drying. As one specific embodiment, a fan 13 is used to air-dry the copolymer chips output from the resin hopper 12 to remove surface moisture.

[0108] Copolyamide chips are highly hygroscopic and their moisture content typically needs to be controlled below 800 ppm, preferably between 400 and 600 ppm, before being used for spinning. As a specific implementation method, before characterizing the copolymer chips or before spinning, the copolymer chips are transferred to a vacuum drying oven and vacuum dried at 100°C to control the moisture content below 800 ppm.

[0109] Furthermore, the continuous polymerization apparatus includes an additive storage tank 8 for storing additives, which can be added to the material during the continuous polymerization process. One or more additive storage tanks 8 can be provided; when two or more additive storage tanks 8 are provided, different types of additives can be stored in different additive storage tanks 8.

[0110] In one specific implementation, the additive storage tank 8 is connected to the tubular temperature programmable device 9 via a pipeline, allowing the additive to be added to the device and mixed with the prepolymer during the temperature programmable process. That is, by connecting the additive storage tank 8 to the tubular temperature programmable device 9, the additive can be added during the temperature programmable stage. Preferably, multiple additive storage tanks 8 are connected to the tubular temperature programmable device 9 via the same pipeline, which simplifies the structure.

[0111] In another specific embodiment, the additive storage tank 8 is connected to the static mixer 3, and the additive is added to a mixture of an aqueous solution of polyamide 56 salt and caprolactam and / or its prepolymer. The additive is mixed together with the mixture and fed into the first stage reactor 5 for prepolymerization, which is equivalent to adding the additive at the prepolymer stage.

[0112] It is understandable that the additive storage tank 8 connected to the tubular programmable heating device 9 and the additive storage tank 8 connected to the static mixer 3 can be set up simultaneously. When producing copolyamide, the additives can be added to the material by controlling the corresponding additive storage tank 8 according to actual needs.

[0113] The technical solution of the present invention will be further described below through specific embodiments, wherein the test items and test methods involved are as follows.

[0114] 1. Extractable content test

[0115] Weigh a sample with a mass of m1 g, pour 50 × m1 g of deionized water into a constant temperature water bath, set the temperature to 100℃, and place the sample in the bath after the temperature is reached. After boiling water extraction for 2 hours, filter out the sample. Repeat the above experiment to accumulate the boiling water extraction time to 24 hours. Under normal temperature and pressure, place the filtered sample in a weighing dish to air dry naturally, then dry it in a regular oven for 8 hours, and then place it in a vacuum oven at 100℃ for 12 hours. Weigh the sample at this time and record it as m2.

[0116] Calculate the extractable content W E %:

[0117] 2. Relative viscosity test method

[0118] The Ubbelohde viscometer concentrated sulfuric acid method was used. 0.5 g of sample was weighed and dissolved in 50 mL of 96.0 wt% concentrated sulfuric acid to prepare a solution with a concentration of 0.01 g / mL. The constant temperature water bath was set to 25 ± 0.02 ℃, and the relative viscosity was tested in the water bath. The time when the solution and pure solvent flowed through the two graduations of the glass bulb of the Ubbelohde viscometer was recorded. Multiple measurements were performed, and the average of three experimental data with a difference of less than or equal to 0.1 s was selected and recorded as t1 and t2, respectively.

[0119] Calculate the relative viscosity η r The calculation formula is: η r = t1 / t2.

[0120] 3. Terminal amino content test

[0121] Accurately weigh 0.3g of the sample, heat and dissolve it in 25mL of a phenol-ethanol mixture (1:1 volume ratio). Slowly add 5 drops of 1g / L thymol blue indicator and titrate with a hydrochloric acid-ethanol solution (of known concentration). The titration endpoint is reached when the solution gradually changes from yellow to pink. Record the volume of hydrochloric acid-ethanol solution consumed to reach the endpoint. Perform multiple parallel experiments on the sample, select data with an error within ±0.1%, take the average value, and prepare two blank control groups.

[0122] The formula for calculating the content of terminal amino groups is:

[0123] Wherein, [-NH2] represents the content of terminal amino groups, in mmol / kg;

[0124] V 试样 The volume of hydrochloric acid-ethanol solution consumed when the sample reaches the titration endpoint, in mL;

[0125] V 空白 The volume of hydrochloric acid-ethanol solution consumed when the blank sample reaches the titration endpoint, in mL;

[0126] C represents the concentration of hydrochloric acid in the hydrochloric acid-ethanol solution, in mol / L.

[0127] m represents the sample mass, expressed in grams.

[0128] 4. Terminal carboxyl group content test

[0129] Accurately weigh 0.2 g of the sample, heat and dissolve it in 25 mL of benzyl alcohol. Slowly add 20 drops of 10 g / L phenolphthalein, and immediately titrate with a potassium hydroxide-benzyl alcohol solution (of known concentration). The titration endpoint is reached when the solution gradually changes from colorless to a slightly pinkish hue. Record the volume of potassium hydroxide-benzyl alcohol solution consumed to reach the endpoint. Perform multiple parallel experiments on the sample, select data with an error within ±0.1%, take the average value, and prepare two blank control groups.

[0130] The formula for calculating the content of terminal carboxyl groups is:

[0131] Wherein, [-COOH] represents the content of terminal carboxyl groups, in mmol / kg;

[0132] V 试样 The volume of potassium hydroxide-benzyl alcohol solution consumed when the sample reaches the titration endpoint is expressed in mL.

[0133] V 空白 The volume of potassium hydroxide-benzyl alcohol solution consumed when the blank sample reaches the titration endpoint is expressed in mL.

[0134] C represents the concentration of potassium hydroxide in the potassium hydroxide-benzyl alcohol solution, in mol / L.

[0135] m represents the sample mass, expressed in grams.

[0136] 5. Thermal stability test method

[0137] A thermogravimetric analyzer (Pyris 1TGA) was used. After drying the sample under nitrogen purging, 1-5 mg of the sample was placed in a crucible and heated from 50 °C to 600 °C at a heating rate of 20 °C / min.

[0138] 6. Melting point detection method

[0139] Weigh 1-2 mg of sample and place it in a crucible for sealed preparation. Under nitrogen protection, test the sample using a differential scanning calorimeter (DSC8000). The temperature rise and fall program is as follows: heat up at 20 °C / min in the temperature range of 30-270 °C, hold at 270 °C for 2 min to eliminate thermal history; then cool down at 20 °C / min in the temperature range of 270-30 °C, hold at 30 °C for 2 min; finally, heat up at 20 °C / min in the temperature range of 30-270 °C.

[0140] Example 1

[0141] The continuous polymerization method in this embodiment includes the following steps:

[0142] 1) Add 17.2 kg of deionized water to a 50 L enamel salt-forming autoclave, then add 9 kg of bio-based pentanediamine and 12.87 kg of adipic acid. Adjust the pH value using a small amount of bio-based pentanediamine (180 g, with a molar ratio of 1.02:1 to adipic acid). After evacuating the autoclave, purge the air with nitrogen gas three times. After protection with nitrogen gas, stir to form salt, obtaining an aqueous solution of polyamide 56 salt. Take a small amount of the salt solution and add it to deionized water to prepare a 10 wt% salt solution. The pH value is then tested and found to be 8.40.

[0143] 2) Add 1.151 kg of caprolactam to the salt solution obtained in step 1);

[0144] 3) Add the mixed solution prepared in step 2) into the first 100L polymerization reactor, replace the air with nitrogen, heat with 170℃ heat transfer oil and start stirring, slowly raise the temperature of the mixed solution, maintain normal pressure and exhaust state, react for 3h, the material temperature in the reaction system is 165℃, and the prepolymer is obtained.

[0145] 4) The prepolymer is transported to a tubular programmed temperature riser for programmed temperature rise and pressure hold at 0.2-0.3 MPa (gauge pressure) for 30 minutes. The material temperature in the pipeline outlet area is 230℃.

[0146] 5) The material is conveyed to the second 100L polymerization reactor. The temperature of the material in the reaction system is 275℃. The mixture is continuously stirred and kept under pressure of 0.2~0.3MPa (gauge pressure). After reacting for 2~3 hours, a vacuum is drawn and the vacuum degree is controlled at -0.02MPa (gauge pressure). The vacuuming time is 3 minutes. Then the stirring is stopped and the mixture is allowed to stand for 15 minutes to obtain the copolyamide 56 / 6 melt.

[0147] 6) After polymerization, the material is melted and discharged. After cooling, it is granulated by a pelletizer and then vacuum dried at 100°C before various performance tests are conducted.

[0148] The antigel copolyamide 56 / 6 prepared in this embodiment contains 5 wt% caprolactam and has a copolymer relative viscosity of 2.93.

[0149] Example 2

[0150] The continuous polymerization method in this embodiment includes the following steps:

[0151] 1) Add 17.2 kg of deionized water to a 50 L enamel-lined salt-forming autoclave, then add 9 kg of bio-based pentanediamine and 12.87 kg of adipic acid. Adjust the pH value using a small amount of bio-based pentanediamine (180 g, with a molar ratio of bio-based pentanediamine to adipic acid of 1.02:1). After evacuating the autoclave, purge the air with nitrogen gas three times. After protection with nitrogen gas, stir to form salt, obtaining an aqueous solution of polyamide 56 salt. Take a small amount of the salt solution and add it to deionized water to prepare a 10 wt% salt solution. The pH value is then tested and found to be 8.50.

[0152] 2) Add 2.430 kg of caprolactam to the salt solution prepared in step 1), and simultaneously add 0.3 wt% of the stabilizer SEED, which accounts for 0.3 wt% of the total copolymer.

[0153] 3) Add the mixed solution prepared in step 2) into the first 100L polymerization reactor, replace the air with nitrogen, heat with 170℃ heat transfer oil and start stirring, slowly raise the temperature of the mixed solution, maintain normal pressure and exhaust state, react for 3h, the material temperature in the reaction system is 160℃, and the prepolymer is obtained.

[0154] 4) The prepolymer is transported to a tubular programmed temperature riser for programmed temperature rise and pressure hold at 0.2-0.3 MPa (gauge pressure) for 30 minutes. The material temperature in the pipeline outlet area is 225℃.

[0155] 5) The material is conveyed to the second 100L polymerization reactor. The temperature of the material in the reaction system is 270℃. The mixture is continuously stirred and kept under pressure of 0.2~0.3MPa (gauge pressure). After reacting for 2~3 hours, a vacuum is drawn and the vacuum degree is controlled at -0.02MPa (gauge pressure). The vacuuming time is 3 minutes. Then the stirring is stopped and the mixture is allowed to stand for 15 minutes to obtain the copolyamide 56 / 6 melt.

[0156] (4) After polymerization, the material is melted and discharged. After cooling, it is granulated by a pelletizer and then vacuum dried at 100°C for various performance tests.

[0157] The antigel copolyamide 56 / 6 prepared in this embodiment contains 10 wt% caprolactam and has a copolymer relative viscosity of 2.68.

[0158] Example 3

[0159] The continuous polymerization method in this embodiment includes the following steps:

[0160] 1) Add 17.2 kg of deionized water to a 50 L enamel salt-forming autoclave, then add 9 kg of bio-based pentanediamine and 12.87 kg of adipic acid. Adjust the pH value using a small amount of bio-based pentanediamine (180 g, with a molar ratio of 1.02:1 to adipic acid). After evacuating the autoclave, purge the air with nitrogen three times. Protect the autoclave with nitrogen and stir to form a salt solution, resulting in an aqueous solution of polyamide 56 salt. Take a small amount of the salt solution and add it to deionized water to prepare a 10 wt% salt solution. The pH value is then measured to be 8.46.

[0161] 2) Add 3.859 kg of caprolactam to the salt solution prepared in step 1), along with 0.3 wt% of the stabilizer SEED and 0.3 wt% of the end-capping agent m-phenylenediamine.

[0162] 3) Add the mixed solution prepared in step 2) into the first 100L polymerization reactor, replace the air with nitrogen, heat with 165℃ heat transfer oil and start stirring, slowly raise the temperature of the mixed solution, maintain normal pressure and exhaust state, react for 3h, the material temperature in the reaction system is 160℃, and the prepolymer is obtained.

[0163] 4) The prepolymer is transported to a tubular programmed temperature riser for programmed temperature rise and pressure hold at 0.2-0.3 MPa (gauge pressure) for 30 minutes. The material temperature in the pipeline outlet area is 220℃.

[0164] 5) The material is conveyed to the second 100L polymerization reactor. The temperature of the material in the reaction system is 260℃. The mixture is continuously stirred and kept under pressure of 0.2~0.3MPa (gauge pressure). After reacting for 2~3 hours, a vacuum is drawn and the vacuum degree is controlled at -0.02MPa (gauge pressure). The vacuuming time is 3 minutes. Then the stirring is stopped and the mixture is allowed to stand for 15 minutes to obtain the copolyamide 56 / 6 melt.

[0165] 6) After polymerization, the material is melted and discharged. After cooling, it is granulated by a pelletizer and then vacuum dried at 100°C before various performance tests are conducted.

[0166] The antigel copolyamide 56 / 6 prepared in this embodiment has a caprolactam content of 15 wt% and a copolymer relative viscosity of 2.67.

[0167] Example 4

[0168] The continuous polymerization method in this embodiment includes the following steps:

[0169] 1) Add 17.2 kg of deionized water to a 50 L enamel-lined salt-forming autoclave, then add 9 kg of bio-based pentanediamine and 12.87 kg of adipic acid. Adjust the pH value using a small amount of bio-based pentanediamine (180 g, with a molar ratio of 1.02:1 to adipic acid). After evacuating the autoclave, purge the air with nitrogen gas three times. After protection with nitrogen gas, stir to form salt, obtaining an aqueous solution of polyamide 56 salt. Take a small amount of the salt solution and add it to deionized water to prepare a 10 wt% salt solution. The pH value is then tested to be 7.94.

[0170] 2) Add 5.468 kg of caprolactam to the salt solution prepared in step 1), along with 0.3 wt% of the stabilizer SEED and 0.5 wt% of the end-capping agent decanediamine.

[0171] 3) Add the mixed solution prepared in step 2) into the first 100L polymerization reactor, replace the air with nitrogen, heat with 165℃ heat transfer oil and start stirring, slowly raise the temperature of the mixed solution, maintain normal pressure and exhaust state, react for 3h, the material temperature in the reaction system is 160℃, and the prepolymer is obtained.

[0172] 4) The prepolymer is transported to a tubular programmed temperature riser for programmed temperature rise and pressure hold at 0.2-0.3 MPa (gauge pressure) for 30 minutes. The material temperature in the pipeline outlet area is 215℃.

[0173] 5) The material is conveyed to the second 100L polymerization reactor. The temperature of the material in the reaction system is 250℃. The mixture is continuously stirred and kept under pressure of 0.2~0.3MPa (gauge pressure). After reacting for 2~3 hours, a vacuum is drawn and the vacuum degree is controlled at -0.02MPa (gauge pressure). The vacuuming time is 3 minutes. Then the stirring is stopped and the mixture is allowed to stand for 15 minutes to obtain the copolyamide 56 / 6 melt.

[0174] 6) After polymerization, the material is melted and discharged. After cooling, it is granulated by a pelletizer and then vacuum dried at 100°C before various performance tests are conducted.

[0175] The antigel copolyamide 56 / 6 prepared in this embodiment has a caprolactam content of 20 wt% and a copolymer relative viscosity of 2.77.

[0176] Example 5

[0177] The continuous polymerization method in this embodiment includes the following steps:

[0178] 1) Add 17.2 kg of deionized water to a 50 L enamel salt-forming autoclave, then add 9 kg of bio-based pentanediamine and 12.87 kg of adipic acid. Adjust the pH value using a small amount of bio-based pentanediamine (180 g, with a molar ratio of 1.02:1 to adipic acid). After evacuating the autoclave, purge the air with nitrogen three times. Protect the autoclave with nitrogen and stir to form a salt solution, resulting in an aqueous solution of polyamide 56 salt. Take a small amount of the salt solution and add it to deionized water to prepare a 10 wt% salt solution. The pH value is 8.02.

[0179] 2) Add 7.290 kg of caprolactam to the salt solution prepared in step 1), along with 0.3 wt% of the stabilizer SEED and 0.2 wt% of the total copolymer.

[0180] 3) Add the mixed solution prepared in step 2) into the first 100L polymerization reactor, replace the air with nitrogen, heat with 160℃ heat transfer oil and start stirring, slowly raise the temperature of the mixed solution, maintain normal pressure and exhaust state, react for 3h, the material temperature in the reaction system is 155℃, and the prepolymer is obtained.

[0181] 4) The prepolymer is transported to a tubular programmed temperature riser for programmed temperature rise and pressure is maintained at 0.2-0.3 MPa (gauge pressure) for 30 minutes. The material temperature in the pipeline outlet area is 210℃.

[0182] 5) The material is conveyed to the second 100L polymerization reactor. The temperature of the material in the reaction system is 245℃. The mixture is continuously stirred and kept under pressure of 0.2~0.3MPa (gauge pressure). After reacting for 2~3 hours, a vacuum is drawn and the vacuum degree is controlled at -0.02MPa (gauge pressure). The vacuuming time is 3 minutes. Then the stirring is stopped and the mixture is allowed to stand for 15 minutes to obtain the copolyamide 56 / 6 melt.

[0183] 6) After polymerization, the material is melted and discharged. After cooling, it is granulated by a pelletizer and then vacuum dried at 100°C before various performance tests are conducted.

[0184] The antigel copolyamide 56 / 6 prepared in this embodiment has a caprolactam content of 25 wt% and a copolymer relative viscosity of 2.68.

[0185] Example 6

[0186] The continuous polymerization method in this embodiment includes the following steps:

[0187] 1) Add 17.2 kg of deionized water to a 50 L enamel-lined salt-forming autoclave, then add 9 kg of bio-based pentanediamine and 12.87 kg of adipic acid. Adjust the pH value using a small amount of bio-based pentanediamine (180 g, with a molar ratio of 1.02:1 to adipic acid). After evacuating the autoclave, purge the air with nitrogen gas three times. After protection with nitrogen gas, stir to form salt, obtaining an aqueous solution of polyamide 56 salt. Take a small amount of the salt solution and add it to deionized water to prepare a 10 wt% salt solution. The pH value is then tested and found to be 8.06.

[0188] 2) Add 9.373 kg of caprolactam to the salt solution prepared in step 1), along with 0.3 wt% of the stabilizer 4-amino-2,2,6,6-tetramethylpiperidine and 0.3 wt% of the end-capping agent m-phenylenediamine.

[0189] 3) Add the mixed solution prepared in step 2) into the first 100L polymerization reactor, replace the air with nitrogen, heat with 160℃ heat transfer oil and start stirring, slowly raise the temperature of the mixed solution, maintain normal pressure and exhaust state, react for 3h, the material temperature in the reaction system is 155℃, and the prepolymer is obtained.

[0190] 4) The prepolymer is transported to a tubular programmed temperature riser for programmed temperature rise and pressure is maintained at 0.2-0.3 MPa (gauge pressure) for 30 minutes. The material temperature in the pipeline outlet area is 205℃.

[0191] 5) The material is conveyed to the second 100L polymerization reactor. The temperature of the material in the reaction system is 240℃. The mixture is continuously stirred and kept under pressure of 0.2~0.3MPa (gauge pressure). After reacting for 2~3 hours, a vacuum is drawn and the vacuum degree is controlled at -0.02MPa (gauge pressure). The vacuuming time is 3 minutes. Then the stirring is stopped and the mixture is allowed to stand for 15 minutes to obtain the copolyamide 56 / 6 melt.

[0192] 6) After polymerization, the material is melted and discharged. After cooling, it is granulated by a pelletizer and then vacuum dried at 100°C before various performance tests are conducted.

[0193] The antigel copolyamide 56 / 6 prepared in this embodiment has a caprolactam content of 30 wt% and a copolymer relative viscosity of 2.74.

[0194] Example 7

[0195] The continuous polymerization method in this embodiment includes the following steps:

[0196] 1) Add 17.2 kg of deionized water to a 50 L enamel-lined salt-forming autoclave, then add 9 kg of bio-based pentanediamine and 12.87 kg of adipic acid. Adjust the pH value using a small amount of bio-based pentanediamine (180 g, with a molar ratio of 1.02:1 to adipic acid). After evacuating the autoclave, purge the air with nitrogen gas three times. After protection with nitrogen gas, stir to form salt, obtaining an aqueous solution of polyamide 56 salt. Take a small amount of the salt solution and add it to deionized water to prepare a 10 wt% salt solution. The pH value is then tested and found to be 8.10.

[0197] 2) Add 11.776 kg of caprolactam to the salt solution prepared in step 1), along with 0.3 wt% of the stabilizer 4-amino-2,2,6,6-tetramethylpiperidine and 0.5 wt% of the end-capping agent decanediamine.

[0198] 3) Add the mixed solution prepared in step (2) into the first 100L polymerization reactor, replace the air with nitrogen, heat with 160℃ heat transfer oil and start stirring, slowly raise the temperature of the mixed solution, maintain normal pressure exhaust state, react for 3h, the material temperature in the reaction system is 155℃, and the prepolymer is obtained.

[0199] 4) The prepolymer is transported to a tubular programmed temperature riser for programmed temperature rise and pressure holding at 0.2-0.3 MPa (gauge pressure) for 30 minutes. The material temperature in the pipeline outlet area is 200℃.

[0200] 5) The material is conveyed to the second 100L polymerization reactor. The temperature of the material in the reaction system is 240℃. The mixture is continuously stirred and kept under pressure of 0.2~0.3MPa (gauge pressure). After reacting for 2~3 hours, a vacuum is drawn and the vacuum degree is controlled at -0.02MPa (gauge pressure). The vacuuming time is 3 minutes. Then the stirring is stopped and the mixture is allowed to stand for 15 minutes to obtain the copolyamide 56 / 6 melt.

[0201] 6) After polymerization, the material is melted and discharged. After cooling, it is granulated by a pelletizer and then vacuum dried at 100°C before various performance tests are conducted.

[0202] The antigel copolyamide 56 / 6 prepared in this embodiment contains 35 wt% caprolactam and has a copolymer relative viscosity of 2.68.

[0203] Example 8

[0204] The continuous polymerization method in this embodiment includes the following steps:

[0205] 1) Add 17.2 kg of deionized water to a 50 L enamel-lined salt-forming autoclave, then add 9 kg of bio-based pentanediamine and 12.87 kg of adipic acid. Adjust the pH value using a small amount of bio-based pentanediamine (180 g, with a molar ratio of 1.02:1 to adipic acid). After evacuating the autoclave, purge the air with nitrogen gas three times. After protection with nitrogen gas, stir to form salt, obtaining an aqueous solution of polyamide 56 salt. Take a small amount of the salt solution and add it to deionized water to prepare a 10 wt% salt solution. The pH value is then tested and found to be 8.03.

[0206] 2) Add 14.580 kg of caprolactam to the salt solution prepared in step 1), along with 0.3 wt% of the stabilizer 4-amino-2,2,6,6-tetramethylpiperidine and 0.2 wt% of the total copolymer.

[0207] 3) Add the mixed solution prepared in step 2) into the first 100L polymerization reactor, replace the air with nitrogen, heat with 160℃ heat transfer oil and start stirring, slowly raise the temperature of the mixed solution, maintain normal pressure and exhaust state, react for 3h, the material temperature in the reaction system is 155℃, and the prepolymer is obtained.

[0208] 4) The prepolymer is transported to a tubular programmed temperature riser for programmed temperature rise and pressure is maintained at 0.2-0.3 MPa (gauge pressure) for 30 minutes. The material temperature in the pipeline outlet area is 195℃.

[0209] 5) The material is conveyed to the second 100L polymerization reactor. The temperature of the material in the reaction system is 240℃. The mixture is continuously stirred and kept under pressure of 0.2~0.3MPa (gauge pressure). After reacting for 2~3 hours, a vacuum is drawn and the vacuum degree is controlled at -0.02MPa (gauge pressure). The vacuuming time is 3 minutes. Then the stirring is stopped and the mixture is allowed to stand for 15 minutes to obtain the copolyamide 56 / 6 melt.

[0210] 6) After polymerization, the material is melted and discharged. After cooling, it is granulated by a pelletizer and then vacuum dried at 100°C before various performance tests are conducted.

[0211] The antigel copolyamide 56 / 6 prepared in this embodiment has a caprolactam content of 40 wt% and a copolymer relative viscosity of 2.83.

[0212] Comparative Example 1

[0213] This comparative example uses a single-reactor polymerization method to prepare copolyamide 56 / 6, and the raw materials and proportions used are the same as in Example 4. Specifically, it includes the following steps:

[0214] 1) Add 17.2 kg of deionized water to a 50 L enamel salt-forming autoclave, then add 9 kg of bio-based pentanediamine and 12.87 kg of adipic acid. Adjust the pH value using a small amount of bio-based pentanediamine (180 g, with a molar ratio of 1.02:1 to adipic acid). After evacuating the autoclave, purge the air with nitrogen three times. Protect the autoclave with nitrogen and stir to form a salt solution, resulting in an aqueous solution of polyamide 56 salt. Take a small amount of the salt solution and add it to deionized water to prepare a 10 wt% salt solution. The pH value is 7.94.

[0215] 2) Add 5.468 kg of caprolactam to the salt solution prepared in step 1), along with 0.3 wt% of the stabilizer SEED and 0.5 wt% of the end-capping agent decanediamine.

[0216] 3) Add the mixed solution prepared in step (2) into a 100L polymerization reactor, replace the air with nitrogen, heat with 165℃ heat transfer oil and start stirring, slowly raise the temperature of the mixed solution, maintain normal pressure exhaust state, react for 3h, the material temperature in the reaction system is 160℃, and the prepolymer is obtained.

[0217] 4) The first program heats up to 200℃, holds at a pressure of 0.2-0.3MPa, and reacts for 30 minutes. At the end of the reaction, the temperature of the material in the reaction system is 190.2℃. The second program heats up to 230℃, holds at a pressure of 0.2-0.3MPa, and reacts for 15 minutes. At the end of the reaction, the temperature of the material in the reaction system is 218.2℃.

[0218] 5) Heat to 250℃ for post-polymerization reaction, continuously stir and maintain pressure of 0.2~0.3MPa (gauge pressure), react for 2~3h, then evacuate and control the vacuum degree to -0.02MPa (gauge pressure) for 3min. After that, stop stirring and let stand for 15min to obtain copolyamide 56 / 6 melt.

[0219] 6) After polymerization, the material is melted and discharged. After cooling, it is granulated by a pelletizer and then vacuum dried at 100°C before various performance tests are conducted.

[0220] The copolyamide 56 / 6 prepared in this comparative example has a caprolactam content of 20 wt% and a copolymer relative viscosity of 2.67.

[0221] Comparative Example 2

[0222] This comparative example adjusts the amount of caprolactam used in Example 1 and prepares copolyamide 56 / 6 using the following method:

[0223] 1) Add 17.2 kg of deionized water to a 50 L enamel-lined salt-forming autoclave, then add 9 kg of bio-based pentanediamine and 12.87 kg of adipic acid. Adjust the pH value using a small amount of bio-based pentanediamine (180 g, with a molar ratio of 1.02:1 to adipic acid). After evacuating the autoclave, purge the air with nitrogen three times. Protect the autoclave with nitrogen and stir to form a salt solution, resulting in an aqueous solution of polyamide 56 salt. Take a small amount of the salt solution and add it to deionized water to prepare a 10 wt% salt solution. The pH value is 8.24.

[0224] 2) Add 32.8 kg of caprolactam to the salt solution prepared in step 1);

[0225] 3) Add the mixed solution prepared in step 2) into the first 100L polymerization reactor, replace the air with nitrogen, heat with 160℃ heat transfer oil and start stirring, slowly raise the temperature of the mixed solution, maintain normal pressure and exhaust state, react for 3h, the material temperature in the reaction system is 155℃, and the prepolymer is obtained.

[0226] 4) The prepolymer is transported to a tubular programmed temperature riser for programmed temperature rise and pressure is maintained at 0.2-0.3 MPa (gauge pressure) for 30 minutes. The material temperature in the pipeline outlet area is 190℃.

[0227] 5) The material is conveyed to the second 100L polymerization reactor. The temperature of the material in the reaction system is 230℃. The mixture is continuously stirred and kept under pressure of 0.2~0.3MPa (gauge pressure). After reacting for 2~3 hours, a vacuum is drawn and the vacuum degree is controlled at -0.02MPa (gauge pressure). The vacuuming time is 3 minutes. Then the stirring is stopped and the mixture is allowed to stand for 15 minutes to obtain the copolyamide 56 / 6 melt.

[0228] 6) After polymerization, the material is melted and discharged. After cooling, it is granulated by a pelletizer and then vacuum dried at 100°C before various performance tests are conducted.

[0229] The copolyamide 56 / 6 prepared in this comparative example has a caprolactam content of 60 wt% and a copolymer relative viscosity of 2.71.

[0230] Based on Example 3, the amount of caprolactam was adjusted to obtain Examples 9-12.

[0231] Example 9

[0232] The continuous polymerization method in this embodiment includes the following steps:

[0233] 1) Add 17.2 kg of deionized water to a 50 L enamel-lined salt-forming autoclave, then add 9 kg of bio-based pentanediamine and 12.87 kg of adipic acid. Adjust the pH value using a small amount of bio-based pentanediamine (180 g, with a molar ratio of 1.02:1 to adipic acid). After evacuating the autoclave, purge the air with nitrogen gas three times. After protection with nitrogen gas, stir to form salt, obtaining an aqueous solution of polyamide 56 salt. Take a small amount of the salt solution and add it to deionized water to prepare a 10 wt% salt solution. The pH value is then tested and found to be 8.34.

[0234] 2) Add 2.430 kg of caprolactam to the salt solution prepared in step 1), along with 0.3 wt% of the stabilizer SEED and 0.3 wt% of the end-capping agent m-phenylenediamine.

[0235] 3) Add the mixed solution prepared in step 2) into the first 100L polymerization reactor, replace the air with nitrogen, heat with 170℃ heat transfer oil and start stirring, slowly raise the temperature of the mixed solution, maintain normal pressure and exhaust state, react for 3h, the material temperature in the reaction system is 160℃, and the prepolymer is obtained.

[0236] 4) The prepolymer is transported to a tubular programmed temperature riser for programmed temperature rise and pressure hold at 0.2-0.3 MPa (gauge pressure) for 30 minutes. The material temperature in the pipeline outlet area is 225℃.

[0237] 5) The material is conveyed to the second 100L polymerization reactor. The temperature of the material in the reaction system is 270℃. The mixture is continuously stirred and kept under pressure of 0.2~0.3MPa (gauge pressure). After reacting for 2~3 hours, a vacuum is drawn and the vacuum degree is controlled at -0.02MPa (gauge pressure). The vacuuming time is 3 minutes. Then the stirring is stopped and the mixture is allowed to stand for 15 minutes to obtain the copolyamide 56 / 6 melt.

[0238] 6) After polymerization, the material is melted and discharged. After cooling, it is granulated by a pelletizer and then vacuum dried at 100°C before various performance tests are conducted.

[0239] The antigel copolyamide 56 / 6 prepared in this embodiment has a caprolactam content of 10 wt% and a copolymer relative viscosity of 2.72.

[0240] Example 10

[0241] 1) Add 17.2 kg of deionized water to a 50 L enamel salt-forming autoclave, then add 9 kg of bio-based pentanediamine and 12.87 kg of adipic acid. Adjust the pH value using a small amount of bio-based pentanediamine (180 g, with a molar ratio of 1.02:1 to adipic acid). After evacuating the autoclave, purge the air with nitrogen three times. Protect the autoclave with nitrogen and stir to form a salt solution, resulting in an aqueous solution of polyamide 56 salt. Take a small amount of the salt solution and add it to deionized water to prepare a 10 wt% salt solution. The pH value is 8.02.

[0242] 2) Add 5.468 kg of caprolactam to the salt solution prepared in step 1), along with 0.3 wt% of the stabilizer SEED and 0.3 wt% of the end-capping agent m-phenylenediamine.

[0243] 3) Add the mixed solution prepared in step (2) into the first 100L polymerization reactor, replace the air with nitrogen, heat with 165℃ heat transfer oil and start stirring, slowly raise the temperature of the mixed solution, maintain normal pressure exhaust state, react for 3h, the material temperature in the reaction system is 160℃, and the prepolymer is obtained.

[0244] 4) The prepolymer is transported to a tubular programmed temperature riser for programmed temperature rise and pressure hold at 0.2-0.3 MPa (gauge pressure) for 30 minutes. The material temperature in the pipeline outlet area is 215℃.

[0245] 5) The material is conveyed to the second 100L polymerization reactor. The temperature of the material in the reaction system is 250℃. The mixture is continuously stirred and kept under pressure of 0.2~0.3MPa (gauge pressure). After reacting for 2~3 hours, a vacuum is drawn and the vacuum degree is controlled at -0.02MPa (gauge pressure). The vacuuming time is 3 minutes. Then the stirring is stopped and the mixture is allowed to stand for 15 minutes to obtain the copolyamide 56 / 6 melt.

[0246] 6) After polymerization, the material is melted and discharged. After cooling, it is granulated by a pelletizer and then vacuum dried at 100°C before various performance tests are conducted.

[0247] The antigel copolyamide 56 / 6 prepared in this embodiment has a caprolactam content of 20 wt% and a copolymer relative viscosity of 2.73.

[0248] Example 11

[0249] 1) Add 17.2 kg of deionized water to a 50 L enamel-lined salt-forming autoclave, then add 9 kg of bio-based pentanediamine and 12.87 kg of adipic acid. Adjust the pH value using a small amount of bio-based pentanediamine (180 g, with a molar ratio of 1.02:1 to adipic acid). After evacuating the autoclave, purge the air with nitrogen gas three times. After protection with nitrogen gas, stir to form salt, obtaining an aqueous solution of polyamide 56 salt. Take a small amount of the salt solution and add it to deionized water to prepare a 10 wt% salt solution. The pH value is then tested and found to be 8.06.

[0250] 2) Add 9.373 kg of caprolactam to the salt solution prepared in step 1), along with 0.3 wt% of the stabilizer SEED and 0.3 wt% of the end-capping agent m-phenylenediamine.

[0251] 3) Add the mixed solution prepared in step 2) into the first 100L polymerization reactor, replace the air with nitrogen, heat with 160℃ heat transfer oil and start stirring, slowly raise the temperature of the mixed solution, maintain normal pressure and exhaust state, react for 3h, the material temperature in the reaction system is 155℃, and the prepolymer is obtained.

[0252] 4) The prepolymer is transported to a tubular programmed temperature riser for programmed temperature rise and pressure is maintained at 0.2-0.3 MPa (gauge pressure) for 30 minutes. The material temperature in the pipeline outlet area is 205℃.

[0253] 5) The material is conveyed to the second 100L polymerization reactor. The temperature of the material in the reaction system is 240℃. The mixture is continuously stirred and kept under pressure of 0.2~0.3MPa (gauge pressure). After reacting for 2~3 hours, a vacuum is drawn and the vacuum degree is controlled at -0.02MPa (gauge pressure). The vacuuming time is 3 minutes. Then the stirring is stopped and the mixture is allowed to stand for 15 minutes to obtain the copolyamide 56 / 6 melt.

[0254] 6) After polymerization, the material is melted and discharged. After cooling, it is granulated by a pelletizer and then vacuum dried at 100°C before various performance tests are conducted.

[0255] The antigel copolyamide 56 / 6 prepared in this embodiment has a caprolactam content of 30 wt% and a copolymer relative viscosity of 2.72.

[0256] Example 12

[0257] 1) Add 17.2 kg of deionized water to a 50 L enamel-lined salt-forming autoclave, then add 9 kg of bio-based pentanediamine and 12.87 kg of adipic acid. Adjust the pH value using a small amount of bio-based pentanediamine (180 g, with a molar ratio of 1.02:1 to adipic acid). After evacuating the autoclave, purge the air with nitrogen gas three times. After protection with nitrogen gas, stir to form salt, obtaining an aqueous solution of polyamide 56 salt. Take a small amount of the salt solution and add it to deionized water to prepare a 10 wt% salt solution. The pH value is then tested and found to be 8.03.

[0258] 2) Add 14.58 kg of caprolactam to the salt solution prepared in step 1), along with 0.3 wt% of the stabilizer SEED and 0.3 wt% of the end-capping agent m-phenylenediamine.

[0259] 3) Add the mixed solution prepared in step (2) into the first 100L polymerization reactor, replace the air with nitrogen, heat with 160℃ heat transfer oil and start stirring, slowly raise the temperature of the mixed solution, maintain normal pressure exhaust state, react for 3h, the material temperature in the reaction system is 155℃, and the prepolymer is obtained.

[0260] 4) The prepolymer is transported to a tubular programmed temperature riser for programmed temperature rise and pressure is maintained at 0.2-0.3 MPa (gauge pressure) for 30 minutes. The material temperature in the pipeline outlet area is 195℃.

[0261] 5) The material is conveyed to the second 100L polymerization reactor. The temperature of the material in the reaction system is 240℃. The mixture is continuously stirred and kept under pressure of 0.2~0.3MPa (gauge pressure). After reacting for 2~3 hours, a vacuum is drawn and the vacuum degree is controlled at -0.02MPa (gauge pressure). The vacuuming time is 3 minutes. Then the stirring is stopped and the mixture is allowed to stand for 15 minutes to obtain the copolyamide 56 / 6 melt.

[0262] 6) After polymerization, the material is melted and discharged. After cooling, it is granulated by a pelletizer and then vacuum dried at 100°C before various performance tests are conducted.

[0263] The antigel copolyamide 56 / 6 prepared in this embodiment has a caprolactam content of 40 wt% and a copolymer relative viscosity of 2.78.

[0264] The composition and formulation of the copolyamide 56 / 6 obtained in the above embodiments and comparative examples are shown in Table 1.

[0265] Table 1

[0266]

[0267] The copolyamide 56 / 6 prepared in the above examples and comparative examples were tested. The test results of the relative viscosity of the chips and the content of terminal amino and terminal carboxyl groups are shown in Table 2. The test results of the extractable content and melting point are shown in Table 3. The test results of the thermal stability are shown in Table 4.

[0268] Table 2

[0269] Sample number Slice relative viscosity Terminal amino group content (mmol / kg) Terminal carboxyl group content (mmol / kg) Example 1 2.93 45.13 88.85 Example 2 2.68 70.68 110.67 Example 3 2.67 139.99 23.26 Example 4 2.77 117.54 37.53 Example 5 2.68 133.45 25.67 Example 6 2.74 123.12 25.87 Example 7 2.68 126.87 30.65 Example 8 2.83 101.32 25.68 Comparative Example 1 2.67 110.32 45.73 Comparative Example 2 2.71 41.12 89.23 Example 9 2.72 113.40 31.56 Example 10 2.73 121.12 29.85 Example 11 2.72 120.32 30.42 Example 12 2.78 110.22 28.44

[0270] As can be seen from the above results, the relative viscosity of the copolymer chips obtained in each embodiment and comparative example is controlled at around 2.7 to 2.9. Within this relative viscosity range, the melt flowability and melt strength of copolyamide 56 / 6 are good. In actual spinning experiments, excessively high relative viscosity of copolyamide 56 / 6 chips leads to poor melt flowability. This problem can usually only be solved by increasing the spinning temperature, but excessively high spinning temperatures can cause gelation of the copolyamide 56 / 6 melt, which is detrimental to spinning. Conversely, excessively low relative viscosity of copolyamide 56 / 6 chips results in low melt strength during spinning, which is also unfavorable, leading to low spinnability of the chips.

[0271] Diamines were added as end-capping agents in the polymerization experiments of Examples 3-12 and Comparative Example 1. It can be seen that the content of terminal amino groups measured in the above examples and comparative examples is higher. Since acid dyes are usually used for dyeing nylon fibers, the use of end-capping agents can ensure that the copolyamide 56 / 6 chips have sufficient amino groups and acid dyes to bind together.

[0272] Table 3

[0273]

[0274]

[0275] The hydrolysis and ring-opening polymerization of caprolactam to form PA6 prepolymer is a reversible reaction, with a conversion rate of approximately 90% at equilibrium. About 10% by mass of monomers and oligomers remain in the polymer. As shown in Table 3, the content of extractables increases significantly with the increase of the caprolactam feed ratio. To meet processing and application requirements, the oligomer content in the chips needs to be below 2%. A high extractable content leads to a decrease and fluctuation in apparent viscosity during thermal processing and deteriorates the spinning environment during melt spinning. Therefore, the chips require further extraction to meet spinning-grade requirements. Excessive residual monomers and oligomers in the polymer increase the cost of boiling water extraction of the chips and affect their spinnability. Therefore, in this invention, the preferred mass percentage of caprolactam segments in the copolymer is 10wt% to 20wt%, and the monomer and oligomer content in the resulting chips basically meets the spinning-grade requirements.

[0276] Comparing Examples 3 and 9-12, it can be seen that as the mass percentage of caprolactam increases, the melting point of the copolymer gradually decreases, and consequently, the anti-gelling properties also gradually improve. However, in Comparative Example 2, the caprolactam content reached 60 wt%, and compared to the corresponding Example 1, the melting point of the copolymer was significantly lower. When using boiling water to extract the oligomers, the chips melted, making extraction experiments impossible. Furthermore, when used directly for spinning, the excessively high monomer and oligomer content in the chips resulted in poor spinnability.

[0277] Table 4

[0278]

[0279]

[0280] Compared to Example 1, Comparative Example 2 showed a more similar maximum thermal decomposition temperature, but a noticeable difference in the 50% weight loss temperature. The initial thermal decomposition temperature was significantly lower, indicating that the thermal stability of the copolymer decreased significantly when the caprolactam content reached 60 wt%. Therefore, the amount of caprolactam should not be too high, otherwise it will cause a significant decrease in the melting point and thermal decomposition temperature of the copolymer, which is detrimental to downstream applications.

[0281] By comparing the data of Example 4 and Comparative Example 1 in Tables 1 to 3, it can be seen that the test results of the two in various performance tests are quite similar, indicating that the continuous polymerization method of the present invention realizes the continuous polymerization process and can obtain copolymer products with performance comparable to single-reactor polymerization. For industrial production, it can significantly improve production efficiency.

[0282] The copolyamide 56 / 6 prepared using the above examples and comparative examples was used for spinning. Specifically, the copolymer chips were dried in a vacuum drying oven and then spun. The oven temperature was 100°C, and the moisture content of the dried chips was 400-600 ppm.

[0283] The equipment involved in the spinning process and the process parameters are as follows:

[0284] Spinning equipment: Measuring spinning machine;

[0285] Spinneret: 48 holes

[0286] Spinning speed: 3000~4200m / min, preferably 4000m / min;

[0287] Spinning temperature: 220~280℃, preferably 230~275℃.

[0288] The results of the spinning process and the performance tests of the resulting fibers are recorded in Tables 5 and 6.

[0289] Table 5

[0290] Sample number Slice relative viscosity Relative viscosity of oil-free silk Example 1 2.93 3.08 Example 2 2.68 2.78 Example 3 2.67 2.70 Example 4 2.77 2.81 Example 5 2.68 2.73 Example 6 2.74 2.82 Example 7 2.68 2.75 Example 8 2.83 2.91 Comparative Example 1 2.67 2.70 Comparative Example 2 2.71 2.90 Example 9 2.72 2.76 Example 10 2.73 2.78 Example 11 2.72 2.84 Example 12 2.78 2.90

[0291] During the spinning process, PA56 / 6 chips need to be transformed back into melt and pass through the screw, spinning assembly and spinneret. During this process, the molecular chains in the melt will continue to undergo condensation reaction, resulting in an increase in molecular weight. The relative viscosity of the oil-free filament after the melt comes out of the spinneret increases, which will affect the spinnability of the chips.

[0292] As shown in Table 5, compared with Examples 3-12 and Comparative Example 1, Examples 1-2 and Comparative Example 2 did not contain stabilizers. Therefore, the relative viscosity of the oil-free filaments differed significantly from that of the chips. A comparison of Examples 3 and 9-12 shows that the melt with a caprolactam content of 10wt%–20wt% was more stable, and the relative viscosities of the chips and oil-free filaments were closer. Therefore, in the preferred embodiment of the present invention, the caprolactam segment content in the copolymer is controlled to be between 10wt% and 20wt%.

[0293] Table 6

[0294]

[0295] In Table 6 above, in the spinnability classification, "+++++" indicates the best spinnability, and the fewer plus signs, the worse the spinnability.

[0296] Both Example 4 and Comparative Example 1 achieved optimal spinnability, indicating that the present invention, while realizing a continuous polymerization process, does not reduce the spinnability of the copolymers used in the spinning field compared to single-reactor polymerization, thus helping to improve the production efficiency of polymers.

[0297] In Comparative Example 2, the spinning process could not be completed when the caprolactam content reached 60 wt%. Comparison of Examples 3 and 9-10 shows that Examples 3, 9, and 10, under spinning processes with different metering pump frequencies, all exhibited no filament drift, achieving optimal spinnability. Therefore, in the present invention, the caprolactam content is preferably controlled between 10 wt% and 20 wt%, which can lower the melting point and polymerization temperature, reduce gelation, and simultaneously ensure the spinnability of the resulting copolymer.

[0298] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A continuous polymerization method for anti-gelling copolyamide 56 / 6, characterized in that, Includes the following steps: 1) Prepare an aqueous solution of polyamide 56 salt using bio-based pentanediamine and adipic acid; 2) Mix the aqueous solution of polyamide 56 salt obtained in step 1) with the copolymer component, wherein the copolymer component is caprolactam and / or its prepolymer; 3) The mixture from step 2) is fed to the first stage reactor and prepolymerized under normal pressure to form a prepolymer; 4) The prepolymer obtained in step 3) is transported to a tubular temperature-programmed heating device for programmed heating and pressure holding; 5) The material in step 4) is transported to the second stage reactor by the tubular programmed temperature rise device to carry out the post-polymerization reaction and obtain copolyamide 56 / 6 melt; 6) The copolyamide 56 / 6 melt obtained in step 5) is cooled, pelletized, and dried to obtain antigel copolyamide 56 / 6.

2. The continuous polymerization method for anti-gelling copolyamide 56 / 6 according to claim 1, characterized in that, In step 3), the prepolymerization temperature is 135–165°C, and the drainage is maintained at normal pressure. In step 4), the material temperature in the pipeline outlet area of ​​the tubular temperature program device is 190-230℃, and the pressure is maintained at 0.2-0.3MPa; In step 5), the temperature of the post-polymerization reaction is 235-275℃, the pressure is maintained at 0.2-0.3MPa, and after the reaction is completed, a vacuum is drawn and the mixture is allowed to stand to obtain the copolyamide 56 / 6 melt. All pressures mentioned are gauge pressures; Preferably, in step 3), after the prepolymerization begins, the material temperature in the reaction system is 155–165°C, and the residence time is 2–4 hours. Preferably, in step 4), the material temperature in the pipeline outlet area is 195–230°C, and the residence time is 20–40 min; Preferably, in step 5), the material temperature in the post-polymerization reaction system is 235–275°C, and the residence time is 2–4 h.

3. The continuous polymerization method for anti-gelling copolyamide 56 / 6 according to claim 2, characterized in that, In step 5), the vacuuming time is 1 to 3 minutes; Preferably, the vacuum level during evacuation is controlled to be -0.01 to -0.03 MPa; Preferably, the material is stirred while vacuuming, and the stirring speed is 5 to 60 rpm, preferably 10 to 50 rpm; Preferably, the settling time is 5 to 30 minutes, and more preferably 10 to 15 minutes.

4. The continuous polymerization method for anti-gelling copolyamide 56 / 6 according to claim 2, characterized in that, In step 4), the tubular programmed temperature device includes at least two horizontal reactors connected in sequence, and the prepolymer passes through the chambers of each horizontal reactor in sequence. Preferably, the horizontal reactor is provided with a helical propeller inside its cavity, and the rotation of the helical propeller causes the prepolymer to flow from one end to the other within the cavity of the horizontal reactor.

5. The continuous polymerization method for anti-gelling copolyamide 56 / 6 according to any one of claims 1-4, characterized in that, In step 2), the added mass of the copolymer component is 5 wt% to 40 wt% of the total mass of the bio-based pentanediamine, adipic acid, and copolymer component, with a preferred mass percentage of 5 wt% to 30 wt% and a more preferred mass percentage of 10 wt% to 20 wt%.

6. The continuous polymerization method for anti-gelling copolyamide 56 / 6 according to any one of claims 1-4, characterized in that, In step 1), the molar ratio of bio-based pentanediamine to adipic acid is (1.00–1.05):1, preferably (1.02–1.05):1; Preferably, the temperature for preparing polyamide 56 salt is 40–70°C, and more preferably 55–65°C; Preferably, the concentration of the aqueous solution of the polyamide 56 salt is 50 wt% to 70 wt%, more preferably 55 wt% to 70 wt%.

7. The continuous polymerization method for anti-gelling copolyamide 56 / 6 according to any one of claims 1-4, characterized in that, Additives not exceeding 4 wt% of the total copolymer amount are added during the preparation process; Preferably, the amount of the additive added is no more than 2 wt% of the total amount of the copolymer.

8. The continuous polymerization method for anti-gelling copolyamide 56 / 6 according to claim 7, characterized in that, The additives include any one or more combinations of stabilizers, end-capping agents, catalysts, antioxidants, flame retardants, matting agents, weathering agents, gloss enhancers, dyes, crystal nucleating agents, UV stabilizers, plasticizers, and antistatic agents; Preferably, the stabilizer comprises any one or more combinations of bis(2,2,6,6-tetramethyl-3-piperidinamido)-isophthalamide, 4-amino-2,2,6,6-tetramethylpiperidine, N-(5-(1,1)dimethylethyl)-2-ethoxyphenyl)-N'-(2-ethylphenyl)ethylenediamide and N-(2-ethoxyphenyl)-N'-(4-ethylphenyl)ethylenediamide, preferably bis(2,2,6,6-tetramethyl-3-piperidinamido)-isophthalamide or 4-amino-2,2,6,6-tetramethylpiperidine; Preferably, the capping agent comprises any one or more combinations of hexamethylenediamine, decanediamine, m-phenylenediamine, adipic acid, and sebacic acid, and more preferably comprises one or more combinations of hexamethylenediamine, decanediamine, and m-phenylenediamine.

9. An anti-gelling copolyamide 56 / 6, characterized in that, It was prepared by the continuous polymerization method of antigel copolyamide 56 / 6 as described in any one of claims 1-8.

10. The anti-gelling copolyamide 56 / 6 according to claim 9, characterized in that, The antigel copolyamide 56 / 6 has a relative viscosity of 2.60–3.00 and a melting point of 195–250°C.

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