A polymer, its preparation and use

Abstract

The present application relates to a kind of polymer and its preparation method and application.The molecular chain of polymer in it is mainly derived from caprolactam structural unit, thermodynamic stable crystal form is gamma-crystal form, and the tensile strength is higher than nylon 6.The preparation method in it is suitable for low-cost industrial production.

Description

Technical Field

[0001] This invention belongs to the field of organic polymer compounds, specifically relating to a polymer whose molecular chain is mainly composed of structural units derived from caprolactam, its preparation method, and its applications. Background Technology

[0002] Polyamides and polyesters are two major classes of synthetic polymers, differing significantly in properties, applications, and processing. There is a desire in the field to combine the advantages of both, but blending results in poor compatibility, while copolymerization generally leads to a significant reduction in polymer molecular weight and crystallinity, and requires modifications to existing processes, steps, operations, and conditions, making it incompatible with mature polyamide or polyester manufacturing processes. Therefore, these copolymers have not yet achieved large-scale commercialization.

[0003] Polyamide 6 (Nylon 6) possesses excellent properties such as light weight, wear resistance, resistance to acids, alkalis, and some solvents, and ease of molding and processing, thus it is widely used in fibers, engineering plastics, and films. Nylon 6 exists in two crystalline forms, α and γ, with distinct properties and applications. Under certain conditions, these two crystalline forms can interconvert, leading to disordered α / γ crystal mixtures during processing and use. This can cause problems such as decreased product performance, appearance defects, and unreliability in long-term use. The disordered α / γ crystal mixture has always been a challenge in Nylon 6 processing, stemming from the thermodynamic-kinetic contradictions in the hydrogen bond network. Although existing technologies have implemented measures such as process optimization, material modification, and equipment upgrades, the results remain unsatisfactory. New solutions are urgently needed in this field.

[0004] Polyethylene terephthalate (PET) is the world's third largest synthetic polymer after polyethylene and polypropylene, and its cost is lower than that of nylon 6.

[0005] Polymers containing ester and amide bonds have been disclosed in this field. Some of the disclosed polymer molecular chains are mainly linked by ester bonds, with the aim of improving certain properties of polyesters by introducing a small number of amide bonds, such as CN109957107A, CN111040152A, CN103952788A, CN103952791A, CN111440314A, CN101942708A, "Research on Acid Fuel Dyeable Polyester Fibers" (Synthetic Fibers, Vol. 48, No. 1, 2019, pp. 12-13), and "Preparation and Structural Properties Study of Polyamide Ester Based on PA6 Prepolymer" (Synthetic Fiber Industry, Vol. 41, No. 4, 2018, pp. 6-8). Another part discloses random copolymerization using two types of monomers, polyester and polyamide. This method cannot control the polymer molecular chain structure and leads to a decrease in polymer molecular weight and crystallinity, such as CN110054775A, CN115044035A, and CN101469062A.

[0006] CN109706536A discloses a method for preparing nylon 6-based polyamide ester. The method first manufactures a nylon 6 prepolymer in the presence of a catalyst and a diacid end-capping agent; then, it reacts with a diol in the presence of a catalyst to produce an esterified nylon 6 prepolymer; next, it reacts the diol with terephthalic acid in the presence of a catalyst to produce a polyester prepolymer; finally, it reacts the esterified nylon 6 prepolymer with the polyester prepolymer under a vacuum of less than 100 Pa in the presence of a catalyst and an anti-etherifying agent to obtain the nylon 6-based polyamide ester polymer. When the diol is ethylene glycol and the terephthalic acid is terephthalic acid, the product has a melting point of 200℃, a number-average molecular weight of 14000, and a tensile strength of 2.2 cN / dtex. This method uses many raw materials and catalysts, involves complex steps, and requires harsh polymerization conditions, making it incompatible with existing mature processes for nylon 6 and PET. The polymer's melting point, molecular weight, tensile strength, and other properties are lower compared to nylon 6.

[0007] To date, no polymers with molecular chains primarily derived from caprolactam structural units and a stable γ-crystalline form have been disclosed in existing literature.

[0008] The information disclosed in the foregoing background section is only for enhancing the understanding of the background of this application, and may include information not known to those skilled in the art. Summary of the Invention

[0009] One objective of this invention is to provide a novel polymer whose molecular chain is primarily composed of caprolactam-derived structural units and whose stable crystalline form is γ-crystalline. A second objective of this invention is to, while achieving the aforementioned objectives, increase the tensile strength of the polymer to that of Nylon 6. A third objective of this invention is to provide a method for the low-cost industrial production of the aforementioned polymer. A fourth objective of this invention is to provide applications for the aforementioned polymer.

[0010] To achieve the above objectives, the present invention provides the following technical solution.

[0011] 1. A polymer, characterized in that the molecular chain of the polymer is composed of three structural units: -CPL-, -TPA-, and -EG-; wherein the total mass fraction of -TPA- and -EG- is effective to less than 50%; the weight-average molecular weight of the polymer is 40,000 to 200,000; and the thermodynamically stable crystalline form of the polymer is γ-crystalline form.

[0012] 2. The polymer according to the foregoing, characterized in that -TPA- and -EG- are derived from (BHET)x.

[0013] 3. The polymer according to any of the foregoing, characterized in that the total mass fraction of -TPA- and -EG- is 2% to 40%, preferably 3% to 35%, more preferably 4% to 25%.

[0014] 4. The polymer according to any of the foregoing, characterized in that the weight-average molecular weight of the polymer is 50,000 to 200,000, preferably 90,000 to 150,000.

[0015] 5. The polymer according to any of the foregoing, characterized in that the melting point of the polymer is 175°C to 220°C or 185°C to 220°C, preferably 195°C to 215°C or 200°C to 215°C.

[0016] 6. The polymer according to any of the foregoing, characterized in that the crystallinity of the polymer is 15% to 40% or 20% to 40%, preferably 20% to 35%, 20% to 30% or 25% to 35%.

[0017] 7. The polymer according to any of the foregoing, characterized in that the tensile strength of the polymer is 40 MPa to 80 MPa or 50 MPa to 80 MPa.

[0018] 8. The polymer according to any of the foregoing, characterized in that, in the 1H NMR spectrum of the polymer, the area ratio of the m peak to the a peak is 9% to 40%.

[0019] 9. The polymer according to any of the foregoing, characterized in that, in the 1H NMR spectrum of the polymer, the area ratio of peak l to peak a is 0.5% to 10%.

[0020] 10. The polymer according to any of the foregoing, characterized in that the area ratio of the o peak to the a peak in the 1H NMR spectrum of the polymer is 1% to 10%.

[0021] 11. The polymer according to any of the foregoing, characterized in that, in the 1H NMR spectrum of the polymer, the area ratio of the h+g peak to the a peak is 10% to 57%.

[0022] 12. A composition characterized in that it comprises any of the foregoing polymers and an additive selected from reinforcing agents, fillers, toughening agents, plasticizers, flame retardants, colorants, fluorescent whitening agents, light stabilizers, antioxidants, heat stabilizers, lubricants, mold release agents, and combinations thereof, in a mass fraction of greater than 0% to 30%, preferably greater than 0% to 20%, and more preferably greater than 0% to 10%.

[0023] 13. A method for preparing a polymer, comprising a process of hydrolytic ring-opening polymerization of caprolactam to produce polyamide 6, characterized in that (BHET)x, wherein x is 3 to 40, is added during the chain growth stage and / or when the relative viscosity of polyamide 6 is ≥1.1; and the mass fraction of (BHET)x is an effective amount up to less than 50%, based on the total mass of caprolactam and (BHET)x.

[0024] 14. According to any of the aforementioned preparation methods, characterized in that (BHET)x is added when the relative viscosity of polyamide 6 during the chain growth stage is 1.1 to 2.2, preferably 1.5 to 2.

[0025] 15. The preparation method according to any of the foregoing, characterized in that x is 3 to 30 or 7 to 30, preferably 7 to 20 or 7 to 15.

[0026] 16. The preparation method according to any of the foregoing, characterized in that, based on the total mass of caprolactam and (BHET)x, the mass fraction of (BHET)x is 2% to 40%, preferably 3% to 35%, more preferably 4% to 25%.

[0027] 17. A method for producing a polymer, characterized in that the polymer is produced in a polyamide 6 production apparatus according to any of the foregoing preparation methods; wherein the (BHET)x is obtained from a PET production apparatus.

[0028] 18. A polymer, characterized in that it is prepared by any of the foregoing methods.

[0029] 19. An application of a polymer, characterized in that any of the aforementioned polymers is used to manufacture fibers, engineering plastics or films.

[0030] 20. Application of any of the aforementioned polymers in injection molding.

[0031] 21. An article comprising any of the aforementioned polymers or any of the aforementioned compositions.

[0032] 22. The articles described above are selected from textiles, daily necessities, building materials, packaging materials and panels.

[0033] This invention produces a novel polymer whose molecular chain is primarily composed of caprolactam-derived structural units, with a stable γ-crystalline form. Through molecular-scale design, this invention appropriately introduces -TPA- and -EG- groups into the polymer molecular chain, achieving control over the hydrogen bond network of nylon 6. This makes the γ-crystalline form of the polymer thermodynamically more stable, and under conventional processing and usage conditions, the α-crystalline form is essentially impossible to form.

[0034] Specifically, the present invention achieves the following technical effects.

[0035] 1. The polymer molecular chain of the present invention is mainly composed of structural units derived from caprolactam, and the stable crystal form is γ-crystal, which can avoid crystal form transformation and improve processing efficiency;

[0036] 2. The molecular weight of the polymer of the present invention can be equivalent to or higher than that of nylon 6, and under preferred conditions, it is much higher than that of nylon 6;

[0037] 3. The tensile strength of the polymer of the present invention is comparable to or higher than that of nylon 6; under preferred conditions, it is much higher than that of nylon 6;

[0038] 4. The production cost of the polymer of this invention is lower than that of nylon 6;

[0039] 5. The polymerization method of the present invention is compatible with existing nylon 6 and PET production processes and equipment, and is easy to industrialize.

[0040] Other features and advantages of the present invention will be described in detail in the Detailed Description section. Attached Figure Description

[0041] Figure 1 1H NMR spectrum of the polymer in Example 1 of this invention;

[0042] Figure 2 XRD pattern of the polymer in Example 1 of this invention;

[0043] Figure 3 XRD pattern of polyamide 6 in Comparative Example 1;

[0044] Figure 4 XRD pattern of polymer in Comparative Example 2. Detailed Implementation

[0045] The present invention is described in detail below with reference to specific embodiments. However, it should be noted that the scope of protection of the present invention is not limited by these specific embodiments and principle explanations, but is determined by the claims.

[0046] Any implementation described herein may be freely combined with one or more other implementations described herein. Any resulting technical solutions or ideas shall be considered as part of the original disclosure or record of this invention, and shall not be regarded as new content that has not been disclosed or anticipated by this invention, unless those skilled in the art consider the combination to be obviously unreasonable.

[0047] All features disclosed herein can be combined arbitrarily, and such combinations should be considered as specifically disclosed and described herein unless they are obviously unreasonable to those skilled in the art. Any specific numerical value disclosed herein (including the endpoints of a numerical range) is not limited to its exact value, but should be understood to also encompass values ​​close to that exact value, such as all possible values ​​within ±5% of that exact value. Furthermore, with respect to the disclosed numerical range, one or more new numerical ranges can be obtained by arbitrarily combining the endpoint values ​​of the range, the endpoint values ​​with specific point values ​​within the range, and the specific point values ​​themselves; these new numerical ranges should also be considered as specifically disclosed herein.

[0048] Technical and scientific terms used in this article, where definitions are provided, shall be used as the standard; where no definitions are provided, they shall be understood according to their common meaning in the field.

[0049] In this article, "structural unit" refers to the basic structural unit that makes up the polymer molecular chain, which is derived from comonomers such as caprolactam, terephthalic acid, and ethylene glycol.

[0050] In this article, "structural unit derived from A" means a structural unit generated from A through one or more reaction steps.

[0051] In this article, caprolactam can be represented by the symbol CPL, and the structural unit derived from caprolactam can be represented by the symbol -CPL-(-NH-(CH2)5-CO-).

[0052] In this article, terephthalic acid can be represented by the symbol TPA, and the structural unit derived from terephthalic acid can be represented by the symbol -TPA-.

[0053] In this article, ethylene glycol can be represented by the symbol EG, and the structural unit derived from ethylene glycol can be represented by the symbol -EG-.

[0054] In this article, ethylene glycol and terephthalic acid oligomers can be represented by the symbol (BHET)x, where x represents the average degree of polymerization.

[0055] In this article, polyethylene terephthalate can be represented by the symbol PET.

[0056] In this article, polyamide 6, namely polycaprolactam or nylon 6, can be represented by the symbol PA6.

[0057] In this article, thermodynamically stable crystal form refers to the crystal structure with the lowest free energy within the processing and usage conditions of Nylon 6.

[0058] In this article, "optional" means that it can be present or absent. For example, "A and optional B" includes "having A and having B" and "having A but not B".

[0059] The first aspect of the present invention provides a polymer whose molecular chain is composed of three structural units: -CPL-, -TPA-, and -EG-; wherein the total mass fraction of -TPA- and -EG- is an effective amount to less than 50%; the weight-average molecular weight of the polymer is 40,000 to 200,000; and the thermodynamically stable crystalline form of the polymer is γ-crystalline form.

[0060] According to the polymer of the present invention, the "effective amount" refers to the minimum total mass fraction of -TPA- and -EG- sufficient to make the polymer thermodynamically stable in the γ-crystal form.

[0061] It should be understood that PET does not have a γ-crystal form, and the crystalline regions of the polymer are formed by segments composed of -CPL-, which have the same γ-crystal form as nylon 6.

[0062] It should be understood that chemical synthesis aims to avoid the presence of impurities and side reactions, and this invention does not use end-capping agents. However, in actual synthesis, it is impossible to completely eliminate the presence of impurities and side reactions. Using end-capping agents at the chain termination stage of the polymerization reaction (after reaching the target molecular weight) is also a conventional choice in the art. Therefore, the polymers of this invention do not exclude the inclusion of structures in the molecular chain caused by these reasons, as long as they do not constitute a perceptible adverse effect on the performance of the polymers of this invention.

[0063] This invention is not intended to limit the invention through any theoretical explanation. However, it is believed that by appropriately introducing -TPA- and -EG- groups into the molecular chain of nylon 6, the present invention reduces the dihedral angle between hydrogen bonds and the main chain, and reduces the number of hydrogen bonds, thereby directionally inducing the formation of the γ-crystal form while preventing the formation of the α-crystal form. The α-crystal form is more sensitive to cooling rate and temperature gradient, and slight process changes may lead to performance fluctuations; the γ-crystal form is more "tolerant," can be formed at faster cooling rates, is suitable for high-speed continuous production, and is beneficial to improving processing efficiency. In addition, the γ-crystal form has a lower shrinkage rate and better dimensional stability of the product. More importantly, the thermodynamically stable crystalline form of the polymer of the present invention is the γ-crystal form, which does not undergo crystal transformation under processing and use conditions; and its strength is comparable to or significantly higher than that of nylon 6. The present invention has found that the polymer of the present invention remains in the γ-crystal form regardless of whether it is rapidly cooled (e.g., rapidly cooled with cold water) or slowly cooled (e.g., slowly cooled at 100°C).

[0064] According to the polymer of the present invention, the total mass fraction of -TPA- and -EG- is 2% to 40%, preferably 3% to 35%, more preferably 4% to 25%.

[0065] According to the polymer of the present invention, the polymer has a weight-average molecular weight of 50,000 to 200,000, preferably 90,000 to 150,000.

[0066] According to the polymer of the present invention, the polymer has a melting point of 175°C to 220°C or 185°C to 220°C, preferably 195°C to 215°C or 200°C to 215°C.

[0067] According to the polymer of the present invention, the crystallinity of the polymer is 15% to 40% or 20% to 40%, preferably 20% to 35%, 20% to 30%, or 25% to 35%.

[0068] According to the polymer of the present invention, the tensile strength of the polymer is 40 MPa to 80 MPa or 50 MPa to 80 MPa.

[0069] According to the polymer of the present invention, in the 1H NMR spectrum of the polymer, the area ratio of the m peak to the a peak is 9% to 40%. The m peak is the characteristic peak of the benzene ring hydrogen in terephthalic acid diamide, and the a peak is the characteristic peak of the hydrogen at the 4-carbon position in aminohexanoic acid, as shown in schematic formula I:

[0070]

[0071] According to the polymer of the present invention, in the 1H NMR spectrum of the polymer, the area ratio of peak 1 to peak 2a is 0.5% to 10%. Peak 1 is the characteristic hydrogen peak of the hydrogen atom near the amide group in the benzene ring of terephthalic acid monoamide, and peak 2a is the characteristic hydrogen peak of the hydrogen atom at the 4-carbon position in aminohexanoic acid, as shown in schematic formula II:

[0072]

[0073] According to the polymer of the present invention, in the 1H NMR spectrum of the polymer, the area ratio of the o peak to the a peak is 1% to 10%. The o peak is a characteristic peak of the benzene ring hydrogen of diethylene terephthalate, and the a peak is a characteristic peak of the hydrogen at the 4-carbon position in aminohexanoic acid, as shown in schematic formula III:

[0074]

[0075] According to the polymer of the present invention, in the 1H NMR spectrum of the polymer, the area ratio of the h+g peak to the a peak is 10% to 57%. The g and h peaks are characteristic peaks of the hydrogen atoms on the carbons of ethylene glycol in the middle of the molecular chain, and the a peak is a characteristic peak of the hydrogen atom on the 4-carbon position of aminocaproic acid, as shown in schematic formulas IV and V:

[0076]

[0077] According to the polymer of the present invention, in the 1H NMR spectrum of the polymer, the area ratio of the c-peak to the d-peak is 3% to 30%. The c-peak is the H on the methylene group next to the carbonyl group of the ester bond, and the d-peak is the H on the methylene group next to the carbonyl group of the amide bond.

[0078] The present invention also provides a composition comprising any of the aforementioned polymers and an additive selected from reinforcing agents, fillers, toughening agents, plasticizers, flame retardants, colorants, fluorescent whitening agents, light stabilizers, antioxidants, heat stabilizers, lubricants, mold release agents, and combinations thereof, in a mass fraction of greater than 0% to 30%, preferably greater than 0% to 20%, and more preferably greater than 0% to 10%.

[0079] A second aspect of the present invention provides a method for preparing a polymer, comprising a process of producing polyamide 6 by hydrolytic ring-opening polymerization of caprolactam, characterized in that (BHET)x, wherein x is 3 to 40, is added during the chain growth stage and / or when the relative viscosity of polyamide 6 is ≥1.1; and the mass fraction of (BHET)x is an effective amount to less than 50% based on the total mass of caprolactam and (BHET)x.

[0080] According to the polymer preparation method of the present invention, the present invention does not particularly limit the process of producing polyamide 6 by hydrolytic ring-opening polymerization of caprolactam, and any existing known technology can be used, whether it is a batch method or a continuous method.

[0081] As is known in the art, the production of nylon 6 generally involves a hydrolysis ring-opening stage, a chain growth stage, a dehydration and monomer removal stage (vacuum devolatilization stage), and a molding and post-processing stage. During the chain growth stage, the molecular weight of nylon 6 has not yet reached the required level. Therefore, in the dehydration and monomer removal stage, water and small monomer molecules in the system are removed to break the polycondensation equilibrium and further increase the molecular chain length. According to the present invention, (BHET)x should preferably be added during the later stages of the chain growth stage. For more precise control of the molecular weight, (BHET)x can be added when the polyamide 6 reaches a specific relative viscosity, as taught in this invention.

[0082] According to the polymer preparation method of the present invention, it is preferable that no catalyst is used throughout the entire process of manufacturing the polymer.

[0083] As one embodiment of the polymer preparation method of the present invention, the process of producing polyamide 6 by hydrolytic ring-opening polymerization of caprolactam can be as follows: (1) Caprolactam and water react at 150℃~270℃ and atmospheric pressure to 0.6MPa for 1~10h; (2) Add (BHET)x; (3) Continue to react at 220℃~270℃ and negative pressure for 0.5~5h, while removing the generated water.

[0084] According to the aforementioned embodiments of the polymer preparation method, in step (1), the amount of water used is 1% to 5% of the mass of caprolactam.

[0085] According to the aforementioned polymer preparation method, in step (1), caprolactam and water are first reacted at 150°C to 230°C for 0.5h to 3h, and then the temperature is raised to 230°C to 270°C for 1h to 7h.

[0086] According to the aforementioned embodiments of the polymer preparation method, the pressure in step (1) is usually higher than atmospheric pressure. In this case, in step (2), it is preferable to first reduce the pressure to atmospheric pressure and then add (BHET)x.

[0087] According to the aforementioned embodiments of the polymer preparation method, the reaction pressure in step (3) is -0.01MPa to -0.09MPa (gauge pressure), which can be -0.05MPa to -0.08MPa (gauge pressure).

[0088] According to the preparation method of the polymer of the present invention, (BHET)x is added when the chain growth stage and / or the relative viscosity of polyamide 6 is 1.1 to 2.2, preferably 1.5 to 2.

[0089] According to the preparation method of the polymer of the present invention, those skilled in the art can prepare (BHET)x using existing known methods or directly purchase it, depending on the actual situation. In (BHET)x, x is 3–30 or 7–30, preferably 7–20 or 7–15.

[0090] The (BHET)x can be prepared by the following method: the molar ratio of terephthalic acid and ethylene glycol in the esterification reaction is 1:1 to 2, preferably 1:1 to 1.5; the esterification temperature is 200℃ to 270℃, preferably 220℃ to 260℃; the esterification time is 0.5h to 5h, preferably 1h to 3h; and the esterification pressure is 0.1MPa to 1MPa, preferably 0.1MPa to 0.5MPa. The catalyst can be antimony glycolate and sodium acetate.

[0091] According to the aforementioned method for preparing the polymer, based on the total mass of caprolactam and (BHET)x, the mass fraction of (BHET)x is 2% to 40%, preferably 3% to 35%, and more preferably 4% to 25%.

[0092] The aforementioned method for preparing the polymer also includes an optional solid melting step.

[0093] A third aspect of the present invention provides a method for producing a polymer, wherein the polymer is produced in a polyamide 6 production apparatus according to any of the foregoing preparation methods; the (BHET)x can be obtained from a PET production apparatus.

[0094] A fourth aspect of the present invention provides a polymer prepared by any of the foregoing methods.

[0095] A fifth aspect of the invention provides an application of a polymer, wherein any of the aforementioned polymers is used to manufacture fibers, engineering plastics, or films.

[0096] The sixth aspect of the invention provides the use of any of the aforementioned polymers in injection molding.

[0097] A seventh aspect of the invention provides an article comprising any of the aforementioned polymers or any of the aforementioned compositions.

[0098] The articles according to the present invention are selected from textiles, daily necessities, building materials, packaging materials and panels.

[0099] Analysis and characterization

[0100] Relative viscosity test: A ZVISCO-IV2000 fully automatic viscometer was used. The sample was dissolved in 96wt% concentrated sulfuric acid, with a solute-to-solvent ratio of 1(m):100(v). A glass viscometer with a diameter of 1.013mm was selected, and the water bath temperature was 25℃. The solvent and solution were tested three times respectively, with the time difference between the three tests not exceeding 0.01s. The average value was taken to calculate the relative viscosity.

[0101] The molecular chain structures of (BHET)x and the polymer were characterized by 1H NMR. A Bruker AVANCE NEO 500MHz NMR spectrometer was used. Before testing, the polymer was dissolved using deuterated trifluoroacetic acid as a deuteration reagent. The testing conditions were: pulse delay time 10 s, 100 scans, and a testing temperature of 25 °C.

[0102] The molecular weight of the polymer was determined by gel permeation chromatography (GPC) using a PL-GPC50 gel permeation chromatograph, with hexafluoroisopropanol (HFIP) as the solvent. The chromatographic column used was a PL HFIPgel 9μm 7.5×300mm, the test temperature was 40℃, the solvent flow rate was 1.0mL / min, and the injection volume was 100μL.

[0103] The melting point of the polymer was determined by differential scanning calorimetry (DSC3, METLER TOLEDO). The specific method was as follows: (1) Weigh 5 mg of the sample and place it in the sample cell of the DSC3 differential scanning calorimeter. In a nitrogen flow of 50 mL / min, heat the sample from 25 °C to 300 °C at a heating rate of 10 °C / min and hold the temperature for 5 min; (2) Then lower the temperature to 25 °C at a rate of 10 °C / min; (3) Then heat the sample to 300 °C at a rate of 10 °C / min to determine the melting point.

[0104] The polymer crystal form was determined using X-ray diffraction (XRD). The radiation source was Cu-Kα rays (λ = 0.15406 nm), the scan rate was 2° / min, the scan area range was 5°–50°, the voltage was 40 kV, and the current was 30 mA.

[0105] The mechanical properties of the polymer were determined using an electronic universal tensile testing machine (CMT2000, MTS Systems). Samples were dispensed and tested according to ASTM D638-14 standard. The test lead speed was 10 mm / min.

[0106] In the examples, the raw materials and reagents used are shown in Table 1. In the examples, (BHET)x is self-made, and x is 10.

[0107] Table 1

[0108] name Specification source caprolactam Aggregation level Baling Petrochemical Company terephthalic acid Aggregation level Beijing Yili Fine Chemicals Co., Ltd. Ethylene glycol Aggregation level Beijing Yili Fine Chemicals Co., Ltd. Antimony Glycol 99.9％ Beijing Yili Fine Chemicals Co., Ltd. Hexafluoroisopropanol Analytical Pure Tianjin Damao Chemical Reagent Factory Deuterated trifluoroacetic acid Analytical Pure Beijing Yili Fine Chemicals Co., Ltd. Deionized water Sinopec Research Institute of Petroleum Processing Co., Ltd.

[0109] The present invention will be described in detail below through embodiments.

[0110] Preparation Example 1

[0111] This preparation example is used to illustrate the synthesis (BHET). 10 .

[0112] 462g of terephthalic acid (TPA), 259g of ethylene glycol (EG), 0.17g of antimony glycolide, and 0.053g of sodium acetate were added to a 2.5L polymerization reactor. Esterification was carried out at 240℃ and 0.3MPa for 120min, and 100mL of water was removed. The mass of the esterification product was 620g, and the average degree of polymerization of the esterified product was 10.

[0113] Example 1

[0114] This embodiment illustrates the synthesis of the polymer of the present invention.

[0115] Weigh 70g of caprolactam and 2.1g of water into a 250mL high-pressure reactor. At room temperature, purge the reaction system three times with nitrogen gas and maintain this nitrogen atmosphere. Then heat to 100℃ with stirring at 50 rpm. Maintain at 220℃ and 0.2MPa for 2 hours. Increase the temperature to 250℃ and maintain at 0.3MPa for 5 hours. Then reduce the pressure to 0.1MPa; when the relative viscosity is 1.6, add 3.5g of (BHET). 10 The stirring speed was reduced to 30 rpm, and the reaction was continued under reduced pressure at 250℃ for 1 h, with the pressure inside the reactor ranging from -0.05 to -0.08 MPa. The polymer performance test results are shown in Table 2, and the 1H NMR spectrum is shown in [Table 2]. Figure 1 The XRD diffraction pattern of the γ-crystal form is shown in [reference needed]. Figure 2 .

[0116] Example 2

[0117] This embodiment illustrates the synthesis of the polymer of the present invention.

[0118] Weigh 70g of caprolactam and 2.1g of water into a 250mL high-pressure reactor. Purge the reaction system three times with nitrogen at room temperature, maintaining this nitrogen atmosphere. Then heat to 100℃ with stirring at 50rpm. Maintain at 220℃ and 0.2MPa for 2 hours. Increase the temperature to 250℃ and maintain at 0.3MPa for 5 hours. Then reduce the pressure to 0.1MPa; when the relative viscosity is 1.6, add 7.0g of (BHET).10 The stirring speed was reduced to 30 rpm, and the reaction was continued under reduced pressure at 250℃ for 1.5 h, with the pressure inside the reactor ranging from -0.05 to -0.08 MPa. The results of the polymer performance tests are shown in Table 2.

[0119] Example 3

[0120] This embodiment illustrates the synthesis of the polymer of the present invention.

[0121] Weigh 70g of caprolactam and 2.1g of water into a 250mL high-pressure reactor. At room temperature, purge the reaction system three times with nitrogen gas and maintain this nitrogen atmosphere. Then heat to 100℃ with stirring at 50rpm. Maintain at 220℃ and 0.2MPa for 2 hours. Increase the temperature to 250℃ and maintain at 0.3MPa for 5 hours. Then reduce the pressure to 0.1MPa; when the relative viscosity is 1.6, add 10.5g of (BHET). 10 The stirring speed was reduced to 30 rpm, and the reaction was continued under reduced pressure at 250℃ for 1.5 h, with the pressure inside the reactor ranging from -0.05 to -0.08 MPa. The results of the polymer performance tests are shown in Table 2.

[0122] Example 4

[0123] This embodiment illustrates the synthesis of the polymer of the present invention.

[0124] Weigh 70g of caprolactam and 2.1g of water into a 250mL high-pressure reactor. At room temperature, purge the reaction system three times with nitrogen gas and maintain this nitrogen atmosphere. Then heat to 100℃ with stirring at 50rpm. Maintain at 220℃ and 0.2MPa for 2 hours. Increase the temperature to 250℃ and maintain at 0.3MPa for 5 hours. Then reduce the pressure to 0.1MPa; when the relative viscosity is 1.6, add 21g of (BHET). 10 The stirring speed was reduced to 30 rpm, and the reaction was continued under reduced pressure at 250℃ for 2 hours, with the pressure inside the reactor ranging from -0.05 to -0.08 MPa. The results of the polymer performance tests are shown in Table 2.

[0125] Comparative Example 1

[0126] This comparative example is used to illustrate the synthesis of polyamide 6.

[0127] Weigh 70g caprolactam and 2.1g water into a 250mL high-pressure reactor. The reaction system was purged three times with nitrogen at room temperature and maintained under a nitrogen atmosphere. Then, the mixture was heated to 100℃ with stirring at 50rpm. The temperature was maintained at 220℃ and 0.2MPa for 2 hours. The temperature was then increased to 250℃ and maintained at 0.3MPa for 5 hours. The pressure was then reduced to -0.05 to -0.08MPa, and the reaction continued for 2 hours. α-crystalline polyamide 6 was obtained; the XRD pattern is shown below. Figure 3 Other performance test results are shown in Table 2.

[0128] Comparative Example 2

[0129] This comparative example is used to illustrate the polymers synthesized for comparison.

[0130] Weigh 70g caprolactam, 2.1g water, and 3.5g (BHET). 10 The mixture was placed in a 250 mL high-pressure reactor. The reaction system was purged with nitrogen three times under a nitrogen atmosphere at room temperature. Then, it was heated to 100 °C with stirring at 50 rpm. The mixture was maintained at 220 °C and 0.2 MPa for 2 hours. The temperature was then increased to 250 °C and maintained at 0.3 MPa for 5 hours. The pressure was then reduced to -0.05 to -0.08 MPa, the stirring speed was decreased to 30 rpm, and the reaction was continued at 250 °C for 1 hour. An α / γ mixed crystalline caprolactam-based polyesteramide polymer was obtained. This polymer was brittle and lacked strength. The XRD pattern is shown below. Figure 4 Other performance test results are shown in Table 2.

[0131] Table 2

[0132] serial number <![CDATA[Weight average molecular weight, ×10 4 > Melting point, °C Tensile strength, MPa Example 1 11.13 215 49.1 Example 2 14.64 213 70.8 Example 3 11.83 203 64.1 Example 4 4.97 200 42.1 Comparative Example 1 4.68 218 46.5 Comparative Example 2 0.91 204 ---

Claims

1. A polymer, characterized in that, The polymer's molecular chain is composed of three structural units: -CPL-, -TPA-, and -EG-; wherein the total mass fraction of -TPA- and -EG- is effective to less than 50%; the polymer's weight-average molecular weight is 40,000 to 200,000; and the polymer's thermodynamically stable crystal form is γ-.

2. The polymer according to claim 1, characterized in that, The -TPA- and -EG- are derived from (BHET)x, where x is 3 to 40, preferably 3 to 30 or 7 to 30, more preferably 7 to 20 or 7 to 15.

3. The polymer according to claim 1, characterized in that, The total mass fraction of -TPA- and -EG- is 2% to 40%, preferably 3% to 35%, and more preferably 4% to 25%.

4. The polymer according to claim 1, characterized in that, The polymer has a weight-average molecular weight of 50,000 to 200,000, preferably 90,000 to 150,000.

5. The polymer according to claim 1, characterized in that, The polymer has a melting point of 175℃~220℃ or 185℃~220℃, preferably 195℃~215℃ or 200℃~215℃.

6. The polymer according to claim 1, characterized in that, The polymer has a crystallinity of 15%–40% or 20%–40%, preferably 20%–35%, 20%–30%, or 25%–35%.

7. The polymer according to claim 1, characterized in that, The tensile strength of the polymer is 40MPa to 80MPa or 50MPa to 80MPa.

8. The polymer according to claim 1, characterized in that, In the 1H NMR spectrum of the polymer, the area ratio of the m peak to the a peak is 9% to 40%.

9. The polymer according to claim 1, characterized in that, In the 1H NMR spectrum of the polymer, the area ratio of peak l to peak a is 0.5% to 10%.

10. The polymer according to claim 1, characterized in that, In the 1H NMR spectrum of the polymer, the area ratio of the o peak to the a peak is 1% to 10%.

11. The polymer according to claim 1, characterized in that, In the 1H NMR spectrum of the polymer, the area ratio of the h+g peak to the a peak is 10% to 57%.

12. A composition, characterized in that, It includes the polymer of any one of claims 1 to 11 and additives selected from reinforcing agents, fillers, toughening agents, plasticizers, flame retardants, colorants, fluorescent whitening agents, light stabilizers, antioxidants, heat stabilizers, lubricants, mold release agents, and combinations thereof, with a mass fraction of greater than 0% to 30%, preferably greater than 0% to 20%, and more preferably greater than 0% to 10%.

13. A method for preparing a polymer, comprising a process of hydrolytic ring-opening polymerization of caprolactam to produce polyamide 6, characterized in that, When the chain growth stage and / or the relative viscosity of polyamide 6 is ≥1.1, add (BHET)x, where x is 3 to 40; based on the total mass of caprolactam and (BHET)x, the mass fraction of (BHET)x is an effective amount up to less than 50%.

14. The preparation method according to claim 13, characterized in that, When the relative viscosity of polyamide 6 during the chain growth stage is 1.1 to 2.2, preferably 1.5 to 2, (BHET)x is added.

15. The preparation method according to claim 13, characterized in that, The x is 3 to 30 or 7 to 30, preferably 7 to 20 or 7 to 15.

16. The preparation method according to claim 13, characterized in that, Based on the total mass of caprolactam and (BHET)x, the mass fraction of (BHET)x is 2% to 40%, preferably 3% to 35%, and more preferably 4% to 25%.

17. A method for producing a polymer, characterized in that, The polymer is produced in a polyamide 6 production apparatus according to any one of claims 13 to 16; the (BHET)x is obtained from a PET production apparatus.

18. A polymer, characterized in that, Prepared according to any one of claims 13 to 17.

19. An application of a polymer, characterized in that, Any of the polymers of claims 1 to 11 and 18 may be used to manufacture fibers, engineering plastics or films.

20. The use of any of the polymers of claims 1 to 11 and 18 in injection molding.

21. An article comprising the polymer of claims 1 to 11 and 18 or the composition of claim 12.

22. The article of manufacture according to claim 21, wherein the article is selected from textiles, daily necessities, building materials, packaging materials and panels.

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