A segmented polyamide copolymer having a regular structure and a method for preparing the same

Abstract

The application discloses a kind of polyamide copolymer with regular chain segment structure and preparation method thereof, belong to polyamide preparation technical field.The above-mentioned method includes the following steps: (1) using the ester amidation exchange reaction between dimethyl ester and pentanediamine to prepare active nylon segment containing special functional group;(2) the raw materials such as active nylon segment, dibasic acid, first catalyst, high-temperature-resistant solvent are added to reaction kettle, and ion association reaction is carried out at a certain temperature, and polymeric reaction raw material is obtained after discharging, washing, centrifugation and drying;(3) the above-mentioned reaction raw material is added to high-temperature high-pressure reaction kettle, and appropriate amount of water is added to provide pressure, and polyamide prepolymer is obtained by stage polycondensation;(4) polyamide prepolymer and second catalyst are subjected to solid-phase tackification, and polyamide copolymer with regular chain segment structure is prepared.The preparation method of the application can obtain polyamide copolymer with regular structure, and realize the preparation of high-strength, anti-aging and high-temperature-resistant polyamide.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polyamide copolymer preparation, in particular to a polyamide copolymer with regular chain segment structure and a preparation method thereof. BACKGROUND

[0002] Polyamide is widely used in the field of engineering plastics due to its excellent crystallization performance, a large number of hydrogen bonds in the molecular system, high strength, wear resistance and corrosion resistance. At present, according to whether the molecular main chain of polyamide contains benzene ring structure, the existing polyamide categories can be divided into aliphatic polyamide, semi-aromatic polyamide and aromatic polyamide. With the increase of aromatic ring content, the heat resistance is gradually improved, but the introduction of unsaturated aromatic ring easily causes the aging and yellowing of the polymer, and the toughness is reduced. The carbon chain length of monomer in linear aliphatic polyamide determines the melting point and thermal stability, the shorter the carbon chain of the structural unit, the higher the melting point, and the thermal decomposition temperature is reduced. With the increase of the number of carbon atoms, the melting point decreases in a wave shape, and the thermal stability increases, but the mechanical strength is greatly reduced, which cannot meet the application of high-performance engineering plastics in harsh environments.

[0003] In the prior art, the preparation of polyamide is random, and the obtained polyamide chain segment structure is not uniform, the crystallinity is poor, and the mechanical properties and high temperature resistance are seriously affected. SUMMARY

[0004] To solve the above technical problems, the present application provides a polyamide copolymer with regular chain segment structure and a preparation method thereof. The present application reacts dimethyl dicarboxylate with excess pentanediamine to obtain an active nylon segment, then reacts with dicarboxylic acid to obtain a specific structure condensation reaction product, and after condensation and tackifying, an ester ring polyamide copolymer with regular chain segment structure is obtained, which has excellent mechanical properties and high temperature resistance.

[0005] To solve the above technical problems, the present application provides the following technical solutions:

[0006] On the one hand, the present application provides a polyamide copolymer with regular chain segment structure and a preparation method thereof, which comprises the following steps:

[0007] (1) Through ester-amide exchange reaction of dimethyl dicarboxylate and diamine, an active nylon segment with special groups is obtained as a monomer for subsequent reaction;

[0008] (2) A certain amount of active nylon segment, dicarboxylic acid, first catalyst and other raw materials are dissolved in a specific high temperature resistant solvent and added to a reaction kettle, the air in the kettle is replaced with nitrogen, and the ion association reaction is carried out at 120-150 DEG C for 1-4h. After the reaction is completed, the product is discharged, and after centrifugal separation, ethanol washing and vacuum drying, a specific structure condensation reaction product is obtained;

[0009] (3) The above polycondensation reactant, an appropriate amount of water is added to the reaction kettle, the kettle is replaced by nitrogen, and a polyamide prepolymer with a certain molecular weight is obtained by stage melting polycondensation;

[0010] (4) The polyamide prepolymer is mixed with the second catalyst and placed in a vacuum drum dryer to obtain a high molecular weight segmented polyamide copolymer.

[0011] Further, the diacid dimethyl ester in step (1) is one or more of dimethyl adipate, dimethyl sebacate, dimethyl terephthalate, cis-1,4-dimethyl cyclohexane dicarboxylate, and trans-1,4-dimethyl cyclohexane dicarboxylate, and the diacid is one or more of the following: butanedioic acid, hexanedioic acid, nonanedioic acid, decanedioic acid, dodecanedioic acid, terephthalic acid, furan dicarboxylic acid, cis-1,4-cyclohexane dicarboxylic acid, and trans-1,4-cyclohexane dicarboxylic acid. At the same time, when the diacid dimethyl ester is alicyclic structure, the diacid is linear diacid, and when the diacid dimethyl ester is linear structure, the diacid is selected as alicyclic diacid.

[0012] Preferably, the addition ratio of diacid dimethyl ester to pentanediamine in step (1) is 1:2-1:6, and the prepared active nylon segment contains aliphatic amine active groups at both ends. The active nylon segment can be further copolymerized as an amide macromonomer with active ends.

[0013] Preferably, in step (1), the specific steps of the ester-amide exchange reaction are as follows: an excess of 1,5-pentanediamine is added to a 500 mL three-necked flask with mechanical stirring and condensing device, protected by nitrogen, then slowly drop the diacid dimethyl ester at 80°C, the drop rate is 0.4-0.6 mL / min, after the system changes from heterogeneous to homogeneous, the temperature is raised to 90-120°C and the reaction is continued for 1 h, at this time, the formation of white precipitate can be observed, and the unreacted raw materials are removed by filtration and washing to obtain the active nylon segment.

[0014] Preferably, the specific structure of the polycondensation reactant in step (2) is that two copolymerization units are arranged alternately, i.e. diacid dimethyl ester-diamine-diacid-diamine is sequentially connected, and the preparation method is as follows: equal moles of active nylon segment and diacid, first catalyst are uniformly dissolved in N,N-dimethylformamide, protected by nitrogen, slowly heated to 120-150°C, refluxed for 1-4 h, filtered while hot after a large amount of precipitate is generated, and separated by repeated water washing to obtain the polycondensation reactant.

[0015] Preferably, the catalyst comprises an ester decomposition catalyst and an amide reaction catalyst, the ester decomposition catalyst is one or more of antimony trioxide, tetrabutyl titanate, zinc oxide, organic tin; the amide reaction catalyst is one or more of phosphorous acid, phosphoric acid, sodium phosphite; more preferably, it is a combination of antimony trioxide, tetrabutyl titanate, and sodium phosphite at a ratio of 1:1:2. The amount of the first catalyst is 1% of the total mass of the active nylon segment and the dibasic acid.

[0016] Further, the step (3) includes the following process: 100 parts of the polyamide prepolymer and 20-40 parts of deionized water are added to a high-temperature and high-pressure reaction kettle under nitrogen protection, and after 1h of reaction at 120℃, the prepolymer is made to be miscible with the aqueous solution; the temperature is slowly increased to 220℃, the pressure is controlled to be 2.0-2.1 MPa, and the constant temperature and pressure reaction is maintained for 60-120 min; the gas valve is slowly opened to discharge the moisture in the system, and the temperature is increased to 260-300℃ while the gas is discharged; the key is to match the gas discharge rate with the temperature increase rate, and the temperature in the kettle should be increased by 3-8℃ for each 0.2 MPa decrease in pressure; after returning to normal pressure, the bottom valve is opened to discharge the material, which is crushed and then dried under vacuum at 80℃ to obtain the polyamide prepolymer.

[0017] Further, the step (4) is specifically: the dried polyamide prepolymer and the second catalyst are added to a vacuum drum dryer, and under vacuum, the molecular chain is first thawed at 120℃ for 1h to pre-activate the reactants, and then reacted at 200℃ for 3-6h to obtain a polyamide copolymer with high molecular weight and regular segment structure. The second catalyst is a mixture of sodium triphosphate and ammonium polyphosphate in a certain proportion, and is ground to a particle size similar to that of the prepolymer.

[0018] The reaction flow chart of the application is as follows:

[0019] (1) Preparation of nylon active segment

[0020]

[0021] Wherein, x is 5-12; R1 is one of the following structures:

[0022]

[0023] (2) Synthesis of high-temperature resistant condensation reactant

[0024]

[0025] Wherein, x is 5-12; R1 is

[0026]

[0027] R2 is one of the following structures:

[0028]

[0029] (3) Preparation of the high-temperature resistant prepolymer and final product

[0030]

[0031] wherein x is 5-12, y is 2-10, R1 and R2 are consistent with those in reaction formula (1) and (2).

[0032] Compared with the prior art, the application has the following beneficial effects:

[0033] The application is to prepare a high-temperature resistant polyamide copolymer with regular structure and arranged chain segments. First, an active nylon segment with active groups at both ends is synthesized by an ester-amide exchange reaction. The active nylon segment contains amide groups and has better heat resistance, which can adapt to the high-temperature environment required during the polymerization of the high-temperature resistant polyamide. The preparation of a polycondensation reactant by reacting the active nylon segment with another dibasic acid can introduce other units and ensure the alternating sequence arrangement of the chain segments of the polycondensation reactant. The regular structure ensures that the copolymer has good rigidity and modulus and excellent heat resistance. At the same time, the shortcomings of the traditional random copolymer, such as wide polymerization degree distribution and uneven molecular chain, are solved, so that the copolymer has better mechanical properties. The introduction of the alicyclic structure has better aging resistance than the traditional semi-aromatic high-temperature resistant polyamide. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 DSC curve of the alicyclic polyamide copolymer prepared in Example 1 of the application;

[0035] Figure 2 Thermogravimetric curve of the alicyclic polyamide copolymer prepared in Example 1 of the application;

[0036] Figure 3 FTIR spectrum of the alicyclic polyamide prepared in Example 1 of the application. DETAILED DESCRIPTION

[0037] To make the technical problems, technical solutions and advantages of the application clearer, specific embodiments will be described in detail below with reference to the drawings.

[0038] In the application, the materials and reagents used are commercially available if not otherwise specified.

[0039] The application provides a polyamide copolymer with regular chain segment structure and a preparation method thereof. The specific embodiments are as follows.

[0040] Example 1

[0041] A preparation method of a polyamide copolymer with regular chain segment structure, comprising:

[0042] (1) Slowly add 100 parts of dimethyl adipate into a three-necked flask containing excess 118 parts of pentanediamine, the flask is equipped with mechanical stirring, reflux condenser and is heated to 80°C under nitrogen protection. Control the dropping rate at 0.4 mL / min, and complete the dropping at 80°C, and then increase the reaction temperature to 90°C, continue to react for 1 h, blow out the methanol with nitrogen to promote the esterification reaction, continue to react for 1 h after the clear solution becomes white emulsion, stop heating to obtain the active nylon segment.

[0043] (2) Cool the active nylon segment to 60°C under nitrogen protection, dissolve 98.84 parts of 1,4-cyclohexane dicarboxylic acid and 2 parts of the first catalyst (the first catalyst is a combination of zinc oxide, tetrabutyl titanate and sodium hypophosphite with a mass ratio of 1:1:2) in 110 parts of N,N-dimethylformamide, and slowly add, stir at 120°C for 1 h, obtain a large amount of white precipitate, filter while hot, and wash with ethanol three times, dry to obtain the polyamide polycondensation reactant.

[0044] (3) Add 100 parts of the polycondensation reactant and 40 parts of deionized water into the reaction kettle, replace the air in the kettle with nitrogen, and after reacting at 120°C for 1 h, make the prepolymer and the aqueous solution miscible; slowly heat to 220°C, control the pressure at 2.0-2.1 MPa, keep constant temperature and pressure for 120 min, slowly open the air release valve to discharge the water in the system, and at the same time heat to 290°C, the key is to control the matching of the air release rate and the heating rate, the temperature in the kettle should be increased by 5°C for every 0.2 MPa decrease in pressure, after returning to normal pressure, open the bottom valve to discharge the material, after crushing, dry at 80°C under vacuum to obtain the polyamide prepolymer.

[0045] (4) Add 100 parts of the polyamide prepolymer and 4 parts of the second catalyst (sodium triphosphate and ammonium polyphosphate with a mass ratio of 1:2 are mixed and ground through a 400-mesh sieve to make the particle size similar to that of the prepolymer) into a vacuum drum dryer, first heat to 120°C under vacuum for 1 h to thaw the molecular chain and pre-activate the reactant, and then react at 200°C for 5 h to obtain the polyamide copolymer with high molecular weight and regular segment structure.

[0046] Figure 1is the DSC curve of the segment structure regular polyamide copolymer prepared in Example 1, after annealing heat treatment, the melting point of the copolyamide is 296℃, only one melting peak indicates that the two structural units are completely polymerized, and there is no phase separation phenomenon of different segments, and there is no phenomenon of homopolymerization of two copolymer units. The glass transition temperature is about 110℃, indicating that the copolymer can maintain rigidity in a wide temperature range and has good application potential. There is only one crystallization peak in the cooling process, indicating that the copolymer of the application maintains good sequence structure and does not have the phenomenon of poor crystallization performance caused by random structure, and the crystallization temperature is 248℃.

[0047] Figure 2 is the thermogravimetric curve of the segment structure regular polyamide copolymer prepared in Example 1, which does not have obvious weight loss before 393℃, indicating that it has good thermal stability. The initial decomposition temperature is greatly improved compared with pure linear aliphatic polyamide, indicating that the alicyclic structure can effectively improve the thermal stability. At the same time, the copolymer has only one weight loss process, indicating that the two structural units are completely copolymerized, and the molecular chain is uniform, and there is no copolymer with too high or too low molecular weight.

[0048] Figure 3 is the FTIR spectrum of the segment structure regular polyamide copolymer prepared in Example 1. The absorption peak at 3290cm -1 corresponds to the N-H stretching vibration peak in the amide structure, the absorption peak at 1633cm -1 is the characteristic peak of C=O in the amide, which indicates that the amide structure is successfully prepared. The absorption peaks at 2928cm -1 and 2857cm -1 are the absorption peaks of CH2 in the copolyamide, mainly from aliphatic diamine, dibasic acid and alicyclic structure. The absorption peak at 1545cm -1 corresponds to the bending vibration of N-H in the amide, and the absorption peak at 1459cm -1 is the stretching vibration of C-C structure, mainly from aliphatic carbon chain and alicyclic structure.

[0049] Example 2

[0050] A preparation method of a segment structure regular polyamide copolymer, comprising:

[0051] (1) slowly drop 100 parts of trans-1,4-cyclohexane dimethyl ester into a three-necked flask containing 103 parts of pentanediamine, the three-necked flask is provided with mechanical stirring, reflux condensing device and is raised to 80℃ under nitrogen protection. Control the dropping rate, slowly drop at 80℃, the dropping rate is 0.4mL / min, and the reaction temperature is raised to 100℃, continue to react for 1h, blow out methanol with nitrogen to promote the esterification reaction, continue to react for 1h after the clear solution becomes white emulsion, stop heating to obtain active nylon segment.

[0052] (2) Under nitrogen protection, the active nylon segment is cooled to 60°C, 72.99 parts of adipic acid, 2 parts of the first catalyst (the first catalyst is a combination of zinc oxide, tetrabutyl titanate and sodium hypophosphite with a mass ratio of 1:1:2) is dissolved in 60 parts of N, N-dimethylformamide and slowly added, stirred at 120°C for 1h, after a large amount of white precipitate is obtained, hot filtration is carried out, and washed with ethanol for three times, and dried to obtain a polyamide polycondensation reactant.

[0053] (3) 100 parts of the polycondensation reactant, 40 parts of deionized water are added into the reaction kettle, the air in the kettle is replaced by nitrogen, after 1h reaction at 120°C, the prepolymer is made to be miscible with the aqueous solution; slowly heated to 220°C, the pressure is controlled at 2.0-2.1 MPa, and kept constant temperature and pressure for 120 min, the gas valve is slowly opened to discharge the water in the system, and the temperature is increased to 290°C while the gas is discharged, the key is to control the matching of the gas discharge rate and the heating rate, the temperature in the kettle should be increased by 5°C for every 0.2 MPa pressure drop, after returning to normal pressure, the bottom valve is opened to discharge the material, after crushing, the polyamide prepolymer is obtained by vacuum drying at 80°C.

[0054] (4) 100 parts of the polyamide prepolymer, 4 parts of the catalyst (sodium triphosphate and ammonium polyphosphate with a mass ratio of 1:2 are mixed and ground to a particle size similar to that of the prepolymer) are added into a vacuum drum dryer, and first kept constant temperature at 120°C for 1h under vacuum to thaw the molecular chain and pre-activate the reactant, and then reacted at 200°C for 5h to obtain a high molecular weight polyamide copolymer with regular segment structure.

[0055] Example 3

[0056] A method for preparing a polyamide copolymer with regular segment structure, comprising:

[0057] (1) 100 parts of cis-1,4-dimethyl cyclohexane dicarboxylate is slowly added to a three-necked flask containing 103 parts of pentanediamine, the three-necked flask is provided with mechanical stirring, reflux condensing device and is raised to 80°C under nitrogen protection. The dropping rate is controlled at 0.6 mL / min and the reaction temperature is increased to 100°C under 80°C dropping, and the reaction is continued for 1h, the methanol is blown out by nitrogen to promote the esterification reaction, and when the clear solution becomes white emulsion, the reaction is continued for 1h to stop heating to obtain an active nylon segment.

[0058] Steps (2)-(4) are consistent with example 2, and finally a high molecular weight polyamide copolymer with regular segment structure is obtained.

[0059] To further illustrate the beneficial effects of the present application, a comparative example is constructed as follows

[0060] Comparative Example 1

[0061] A method for preparing a polyamide copolymer, comprising:

[0062] (1) 100 parts of dimethyl adipate, 98.84 parts of 1,4-cyclohexane dicarboxylic acid, 118 parts of pentanediamine, 160 parts of deionized water, and 6 parts of sodium phosphite catalyst are charged into a reaction kettle, the air in the kettle is replaced with nitrogen, and after reaction at 120°C for 1 h, the prepolymer is made miscible with the aqueous solution; the temperature is slowly increased to 220°C, the pressure is controlled at 2.0-2.1 MPa, and constant temperature and pressure reaction is maintained for 120 min; the gas vent valve is slowly opened to discharge the moisture in the system, and while the gas is vented, the temperature is increased to 290°C; the key is to control the matching of the gas venting rate and the temperature increasing rate, and for each 0.2 MPa decrease in pressure, the temperature in the kettle should be increased by 5°C; after returning to normal pressure, the bottom valve is opened to discharge the material, which is ground and then dried at 80°C under vacuum to obtain a polyamide prepolymer.

[0063] (2) 100 parts of the polyamide prepolymer and 4 parts of the catalyst (sodium triphosphate and ammonium polyphosphate mixed at a mass ratio of 1:2 and ground to a particle size similar to that of the prepolymer) are added to a vacuum drum dryer; under vacuum, the molecular chains are first thawed at 120°C for 1 h to pre-activate the reactants, and then the temperature is increased to 200°C for 5 h to obtain a high-temperature-resistant copolyamide containing alicyclic groups.

[0064] Comparative Example 2

[0065] Steps (1) and (2) are the same as in Example 1, and step (3) is:

[0066] 100 parts of the condensation reaction product and 40 parts of deionized water are added to a reaction kettle, the air in the kettle is replaced with nitrogen, and after reaction at 120°C for 1 h, the prepolymer is made miscible with the aqueous solution; the temperature is slowly increased to 220°C, the pressure is controlled at 2.0-2.1 MPa, and constant temperature and pressure reaction is maintained for 120 min; the gas vent valve is slowly opened to discharge the moisture in the system, and while the gas is vented, the temperature is increased to 310°C; the key is to control the matching of the gas venting rate and the temperature increasing rate, and for each 0.2 MPa decrease in pressure, the temperature in the kettle should be increased by 5°C; after returning to normal pressure within 2 h, the reaction kettle is evacuated to -0.09 MPa while maintaining a constant temperature and pressure, and reaction is maintained for 1 h; when the torque rapidly increases, nitrogen is charged, the material is discharged, and the copolyamide is obtained after cooling, granulation, and drying.

[0067] Comparative Example 3

[0068] A preparation method of a polyamide copolymer, comprising: (1) dissolving 100 parts of 1,4-cyclohexane dicarboxylic acid and 59.35 parts of pentanediamine into 80 parts of deionized water, and reacting at 80 DEG C under nitrogen protection for 1 h, and adjusting the pH of the two monomers to 7.5-8.0 to obtain a first condensation reaction product; then dissolving 84.88 parts of adipic acid and 59.35 parts of pentanediamine in 60 parts of deionized water, and reacting at 60 DEG C under nitrogen protection for 1 h, and adjusting the pH of the two monomers to 7.0-7.5 to obtain a second condensation reaction product.

[0069] (2) The first condensation reaction product, the second condensation reaction product and 6 parts of sodium phosphite catalyst are loaded into a reaction kettle, the air in the kettle is replaced by nitrogen, and after reacting at 120 DEG C for 1 h, the prepolymer is made miscible with an aqueous solution; the temperature is slowly increased to 220 DEG C, the pressure is controlled to be 2.0-2.1 MPa, and the reaction is kept constant for 120 min; the gas valve is slowly opened to discharge the water in the system, and the temperature is increased to 290 DEG C at the same time; the key is to control the matching of the gas discharge rate and the temperature increase rate, and the temperature in the kettle should be increased by 5 DEG C for each 0.2 MPa decrease in pressure; after returning to normal pressure, the bottom valve is opened to discharge the material, which is crushed and then dried at 80 DEG C under vacuum to obtain a polyamide prepolymer.

[0070] (2) 100 parts of the polyamide prepolymer and 4 parts of the catalyst (sodium triphosphate and ammonium polyphosphate are mixed at a ratio of 1:2 and ground to a particle size similar to that of the prepolymer) are added to a vacuum drum dryer, and the molecular chains are first thawed at 120 DEG C under vacuum for 1 h to pre-activate the reactants, and then reacted at 200 DEG C for 5 h to obtain a copolyamide.

[0071] Comparative Example 4

[0072] In this comparative example, the catalysts in steps (2) and (4) are omitted, and the other conditions are the same as in Example 1.

[0073] Comparative Example 5

[0074] In this comparative example, the amount of pentanediamine is 59 parts, and the other conditions are the same as in Example 1.

[0075] Comparative Example 6

[0076] In this comparative example, the amount of pentanediamine is 472 parts, and the other conditions are the same as in Example 1.

[0077] Comparative Example 7

[0078] In this comparative example, the dropwise addition rate of dimethyl adipate is 1 mL / min, and the other conditions are the same as in Example 1.

[0079] Comparative Example 8

[0080] In this comparative example, the amount of 1,4-cyclohexane dicarboxylic acid is 197.64 parts, and the other conditions are the same as in Example 1.

[0081] Comparative Example 9

[0082] In this comparative example, the amount of 1,4-cyclohexanedicarboxylic acid was 49.42 parts, and the other conditions were the same as in Example 1.

[0083] Comparative Example 10

[0084] In this comparative example, dimethyl adipate was replaced by an equimolar amount of cis-1,4-cyclohexanedicarboxylic acid dimethyl ester, and the other conditions were the same as in Example 1.

[0085] Comparative Example 11

[0086] In this comparative example, 1,4-cyclohexanedicarboxylic acid was replaced by an equimolar amount of adipic acid, and the other conditions were the same as in Example 1.

[0087] Comparative Example 12

[0088] In this comparative example, the first catalyst was sodium phosphite, and the other conditions were the same as in Example 1.

[0089] Comparative Example 13

[0090] In this comparative example, the first catalyst was zinc oxide and tetrabutyl titanate in a mass ratio of 1:1, and the other conditions were the same as in Example 1.

[0091] Comparative Example 14

[0092] In this comparative example, the reaction temperature in step (2) was 200°C, and the other conditions were the same as in Example 1.

[0093] Comparative Example 15

[0094] In this comparative example, the reaction temperature in step (2) was 100°C, and the other conditions were the same as in Example 1.

[0095] The polyamide copolymer materials prepared in the above examples and comparative examples were subjected to performance testing, wherein the sample preparation and test characterization methods were as follows:

[0096] (1) The polyamide copolymer pellets were dried in a vacuum oven at 100°C for 6 h, and DSC testing was performed using a TA Q2000. 5-8 mg of polyamide pellets were weighed into an aluminum crucible, and the determination program was set to first increase the temperature to 300°C at a rate of 10°C / min, then decrease the temperature to 30°C at a rate of 10°C / min to record the crystallization performance, and finally increase the temperature to 300°C at a rate of 10°C / min to characterize the melting point.

[0097] (2) Thermogravimetric performance testing was performed using a TA Q50. 5-10 mg of polyamide copolymer pellets were weighed into an aluminum crucible, and the determination program was set to increase the temperature to 600°C at a rate of 10°C / min under a nitrogen atmosphere, and the nitrogen flow rate was 50 mL / min.

[0098] (3) The sample of Example 1 was subjected to structural characterization by Agilent Cary 630 infrared spectrometer, the infrared test mode was ATR, and the scanning range was 4000-650 cm -1 .

[0099] (4) Then, according to GB / T 1040 and GB / T 1842, the injection stretch, bending sample was molded by using WZS10 micro injection molding machine under the processing conditions of barrel temperature 300℃, mold temperature 90℃, injection pressure 0.7MPa, and then the tensile and bending tests were carried out. The tensile and bending performance was determined by using Instron 5567 universal testing machine, wherein the tensile rate was 5mm / min, and the temperature was 25℃; the bending rate was 2mm / min, the span was 64, and the temperature was 25℃.

[0100] The above tests were carried out on Examples 1-3 and Comparative Examples 1-4, and the results are shown in Table 1.

[0101] Table 1

[0102]

[0103] As can be seen from Table 1, by comparing Examples 1-2 with Comparative Examples 1 and 3, it can be found that the preparation of active nylon segments and polycondensation reactants to construct an alternating structure can effectively improve the mechanical and thermal properties of the copolyamide. After the ester-amide exchange reaction of dimethyl ester and aliphatic diamine, the reactivity of the monomer can be improved, and the copolymerization system is more stable and compatible. After the active nylon segment is further ion complexed with the diacid to form the polycondensation reactant and then polymerized, the four kinds of monomer units can be arranged in an alternating structure sequence, the copolymer prepared has a regular structure, the alicyclic structure is uniformly distributed, and the performance is better.

[0104] By comparing Example 1 with Comparative Example 2, it can be seen that the solid-phase tackification at a lower temperature in the present application plays an important role in preparing high-performance high-temperature-resistant alicyclic copolyamides. The reason is that the polyamide melt can undergo serious amide exchange reaction at high temperature, leading to the conversion of the chain segment from alternating sequence to random structure, resulting in the decrease of the overall performance. The solid-phase tackification reaction occurs when the polymer is in a solid state, and the active groups at the chain ends further condense, resulting in the increase of the molecular weight, which can effectively protect the designed specific structure.

[0105] Comparative Example 1 and Comparative Example 4 can show that the use of catalysts in the preparation of polycondensation reactants and solid-phase adhesion processes using nylon active segments is the key to effectively promoting the reaction and improving the performance of the product. The ester-amide exchange reaction, the ion complexation reaction of the active nylon segment and the dibasic acid, and the collision reaction of the end group in the solid-phase system are involved in the polymerization system. A single type of catalyst cannot produce a universal promoting effect. Therefore, the formulation design is carried out at different stages according to the characteristics of different reactions to ensure that different types of reactions in the polymerization system have catalytic effects at different reaction stages, and the copolymerization reaction is promoted, which is the key to obtaining high-performance copolyamide materials.

[0106] Comparative Examples 5-15 were tested as described above, and the results are shown in Table 2.

[0107] Table 2

[0108]

[0109]

[0110] As can be seen from the data of Comparative Example 5 and Comparative Example 6, the ratio of the two monomers is the key to successfully preparing the nylon active segment. In Comparative Example 5, the amount of diamine is too small to ensure that the product has active amine group segments at both ends, and the molecular weight of the product is too large, which results in poor solubility. The system is turbid during the preparation of the polycondensation reactant, which cannot fully react, resulting in a large amount of monomers in the copolymer that cannot react, and the mechanical and thermal properties are poor. When an excessive amount of diamine is added in Comparative Example 6, the nylon active segment required for the reaction can be prepared, but too much unreacted pentanediamine causes difficulties in subsequent impurity removal and purification. The unreacted pentanediamine reacts with the dibasic acid during the preparation of the polycondensation reactant, resulting in a deviation of the copolymerization monomer ratio from the preset value, and the acid-amine imbalance, thus greatly reducing the performance of the copolymer product.

[0111] In Comparative Example 7, a large amount of dimethyl dicarboxylate is added to pentanediamine in a short period of time, and part of it cannot be esterified in time under the action of the first catalyst, resulting in the reaction of dimethyl dicarboxylate with the generated active nylon segment, thus forming an oligomer. On the one hand, it reduces the solubility of the active nylon segment, and on the other hand, it makes the amount of active nylon segment not equal to the amount of dibasic acid, thus reducing the performance. Comparative Examples 8 and 9 cannot completely copolymerize because the amount of dibasic acid is not equal to the amount of nylon active segment, and the acid-amine imbalance reduces the degree of reaction.

[0112] In Comparative Example 10, the sequence segment is a cycloaliphatic structure, and the introduction of a large amount of cycloaliphatic structure results in a too high melting point, which makes it difficult to melt during the prepolymerization stage, and the subsequent solid-phase polycondensation process is difficult to greatly increase the molecular weight. Although it has good mechanical properties and heat resistance, it is easily decomposed above the melting point and difficult to process. In Comparative Example 11, no cycloaliphatic structure is introduced, which is a common aliphatic polyamide, and it has no obvious advantage in heat resistance and mechanical properties.

[0113] Comparative Example 12 and Comparative Example 13 show that the catalyst used in the present application is the key to preparing the ester ring polyamide copolymer with regular structure. Different reactions such as aminolysis of ester, ionic complexation, amidation, and solid phase polycondensation are involved in the reaction, and each reaction has different requirements for the catalyst. In Comparative Example 12, only sodium phosphite is added to promote the completion of dehydration and amidation, so the reaction rate of dimethyl dicarboxylate is slow when preparing the active nylon segment, and the introduction of new dimethyl dicarboxylate under the condition that the previously dropped dimethyl ester has not been completely reacted is easy to produce oligomers, thereby reducing the solubility and unbalancing the ratio of active segment to dicarboxylic acid. In Comparative Example 13, only the aminolysis catalyst of ester is added, and no amide reaction catalyst is used under the premise of ensuring the integrity of the polycondensation reactant. Because the molecular weight of the polycondensation reactant is large, the reaction rate is low, and the reaction degree is not enough under the given process, the performance is poor.

[0114] In Comparative Example 14, the temperature is too high when preparing the polycondensation reactant, and a large amount of solvent is volatilized, resulting in reduced solubility of the nylon active segment and incomplete reaction. In Comparative Example 15, the temperature is too low, the nylon active segment cannot be completely dissolved in the solvent, and the reaction rate is slow, so the polycondensation reactant cannot be successfully separated and prepared, and therefore the monomer purity is low and the performance is poor in the subsequent polymerization.

[0115] In summary, the ester ring polyamide copolymer with regular molecular chain segments is obtained by reacting the dimethyl dicarboxylate with a specific ratio with pentanediamine to obtain an active nylon segment, then reacting with dicarboxylic acid to obtain a polycondensation reactant with a specific structure, and then increasing the viscosity by polycondensation. It has excellent mechanical properties and high temperature resistance.

[0116] The above describes the preferred embodiments of the present application, and those of ordinary skill in the art can make some improvements and refinements without departing from the principles of the present application, which should be considered within the scope of protection of the present application.

Claims

1. A process for the preparation of a polyamide copolymer with a regular chain segment structure, characterized in that It comprises the following steps: (1) under the protection of nitrogen, a certain amount of dimethyl dicarboxylate is added to pentanediamine at a rate of 0.4-0.6ml / min, heated to reflux, and an active nylon segment is prepared; The molar ratio of the dimethyl dicarboxylate to the pentanediamine is 1:2-1:6; (2) under the protection of nitrogen, dicarboxylic acid and a first catalyst dispersed in a solvent are slowly added to the active nylon segment in step (1) and reacted at 120-150℃ for 1-4h, after the reaction is completed, the product is discharged, centrifuged, washed with ethanol, and vacuum dried to obtain a polycondensation product; the molar ratio of the dicarboxylic acid to the dimethyl dicarboxylate is 1:1; the first catalyst is composed of an ester decomposition catalyst and an amide reaction catalyst; the ester decomposition catalyst is one or more of antimony trioxide, tetrabutyl titanate, zinc oxide, and organotin; the amide reaction catalyst is one or more of phosphorous acid, phosphoric acid, and sodium phosphite; (3) the above polycondensation product and an appropriate amount of water are added to a reaction kettle, the air in the kettle is replaced with nitrogen, and then stage-wise melt polycondensation is carried out; the stage-wise melt polycondensation is specifically as follows: 100 parts of the polyamide prepolymer and 20-40 parts of deionized water are added to a high-temperature and high-pressure reaction kettle under nitrogen protection, and after reaction at 120℃ for 1h; the temperature is slowly increased to 220℃, the pressure is controlled at 2.0-2.1MPa, and constant temperature and pressure reaction is maintained for 1-2h; the gas discharge valve is slowly opened to discharge the moisture in the system, and while the gas is being discharged, the temperature is increased to 260-300℃; for every 0.2MPa decrease in pressure, the temperature in the kettle should be increased by 3-8℃; after the pressure is returned to normal, the bottom valve is opened to discharge the material, which is crushed and then vacuum dried at 80℃ to obtain the polyamide prepolymer; (4) the polyamide prepolymer and a second catalyst are placed in a vacuum drum dryer, and under vacuum, first constant temperature at 120℃ for 1h, and then reaction at 200℃ for 3-6h to obtain a high molecular weight polyamide copolymer with regular segment structure; the second catalyst is a mixture of sodium triphosphate and ammonium polyphosphate with a mass ratio of 1:2, which is ground through a 400 mesh sieve; The dimethyl dicarboxylate is dimethyl adipate and / or dimethyl sebacate; the dicarboxylic acid is one or more of cis-1,4-cyclohexane dicarboxylic acid and trans-1,4-cyclohexane dicarboxylic acid; Alternatively, the dimethyl dicarboxylate is one or more of cis-1,4-cyclohexane dicarboxylic acid dimethyl ester and trans-1,4-cyclohexane dicarboxylic acid dimethyl ester; the dicarboxylic acid is one or more of succinic acid, adipic acid, azelaic acid, sebacic acid, and dodecanedioic acid.

2. The production method according to claim 1, characterized by, In step (1), pentanediamine is added to a flask with mechanical stirring and condensing device, protected by nitrogen, and then dimethyl dicarboxylate is added at a rate of 0.4-0.6ml / min at 80℃, after the addition is completed, the temperature is increased to 90-120℃ and the reaction is continued for 1h to obtain the active nylon segment.

3. The production method according to claim 1, characterized by, The solvent in step (2) is N,N-dimethylformamide; The amount of the first catalyst is 1% of the total mass of the active nylon segment and the dicarboxylic acid.

4. The method of claim 1, wherein, The first catalyst is a mixture of antimony trioxide, tetrabutyl titanate, and sodium phosphite with a mass ratio of 1:1:

2.

5. A polyamide copolymer of regular chain segment structure, characterized in that, Prepared by the method of any one of claims 1-4.

6. The segmentally regular polyamide copolymer of claim 5, wherein, The structural general formula is as follows: Wherein, x is 5, y is 2-10; Or Wherein, x is 5, y is 2-10.

Images