CN114736369A - Modified nylon and preparation method thereof - Google Patents

Abstract

The invention discloses a modified nylon and a preparation method thereof. The modified nylon has a structure represented by formula (I), in formula (I), a is 5, 6, 10 or 12; x, y, z are the number of repeating units, and are respectively integers from 1 to 20, R ₁ is an aromatic group. The modified nylon of the present invention is resistant to high temperature, and has both higher strength and lower relative viscosity.

Description

Modified nylon and preparation method thereof

technical field

The invention relates to a modified nylon and a preparation method thereof.

Background technique

The melting temperature of most aliphatic polyamides (ie, aliphatic nylons) is lower than 260°C, so they cannot be used in high temperature environments. The introduction of aromatic rings into the main chain of polyamide through molecular structure design can effectively reduce the flexibility of the polyamide molecular chain and increase the glass transition temperature and melting point.

At present, the common high temperature resistant nylons mainly include: polyhexamethylene terephthalamide (PA6T), polynonyl terephthalamide (PA9T), and nonane terephthalamide (PA10T). However, the melting temperature of PA6T exceeds 350 °C, which is difficult to directly synthesize and process. Therefore, it is more to copolymerize PA6T with other components to reduce the melting temperature and increase the toughness of the material. Even so, in order to meet the long-term use in high temperature environment, the melting point of PA6T copolymer is still maintained at about 300 ℃, and the viscosity is relatively large, which puts forward strict requirements for the polymerization process. cause difficulty. In order to deal with this problem, the pre-polymerization-screw extrusion or solid-phase viscosity-increasing process is usually used. However, this process has a long preparation process and low production efficiency, does not completely solve the problem of high melt viscosity, and is difficult to achieve ultra-thin injection molding requirements. Therefore, it is very necessary to provide a modified nylon with relatively low viscosity, high temperature resistance and substantially no reduction in strength and a preparation method thereof.

SUMMARY OF THE INVENTION

In view of this, one object of the present invention is to provide a modified nylon. The obtained modified nylon has high temperature resistance and high strength. In addition, its relative viscosity is low. Another object of the present invention is to provide a method for preparing the modified nylon, which is stable in process, moderate in viscosity during polycondensation, easy to operate, and beneficial to industrial production.

The present invention adopts the following technical solutions to achieve the above objects.

On the one hand, the present invention provides a kind of modified nylon, has the structure shown in formula (I):

In formula (I), a is 5, 6, 10 or 12; x, y, and z are the number of repeating units, respectively, and are integers from 1 to 20;

R ₁ is an aromatic group, which is selected from one of the following groups:

R ₂ is selected from one of the following groups:

R ₃ is selected from one of the following groups:

wherein R ₁ and R ₃ are different.

The modified nylon with such a structure is resistant to high temperature, and its thermodynamic properties including melting point, crystallization temperature, and thermal decomposition temperature are improved, and the mechanical properties are still good, the strength is high, and it can also have a low relative viscosity.

wherein a is 5, 6, 10 or 12, preferably, a is 5, 6 or 10. Each of x, y, and z may be an integer of 1 to 20, preferably an integer of 4 to 20, and more preferably an integer of 5 to 18.

According to the modified nylon of the present invention, preferably:

R ₁ is selected from one of the following groups:

_R2 is

R ₃ is selected from one of the following groups:

According to the modified nylon of the present invention, preferably:

_R1 is

_R3 is

R₂为

R₃为

According to a specific embodiment of the present invention, R ₁ is

_R2 is

_R3 is

On the other hand, the present invention also provides a kind of preparation method of modified nylon as above, comprising the steps:

(1) Under the protection of inert gas, add diamine monomer, aromatic dibasic acid monomer, third monomer, melt viscosity modifier, molecular weight modifier, catalyst, auxiliary agent and water into the reaction kettle , to obtain the first mixture;

(2) react the first mixture at 55-95°C for 0.5-2h; then react at 115-165°C for 0.5-3h; obtain the second mixture;

(3) react the second mixture at 190-215°C and 1.2-1.6MPa for 0.5-2h to obtain the first prepolymer; react the first prepolymer at 210-255°C and 1.8-2.2MPa for 2- 5h, obtain the second prepolymer;

(4) the second prepolymer is heated to 290～325°C in 2～5h, and the reaction kettle is exhausted to normal pressure; then the vacuum is evacuated to the degree of vacuum in the reaction kettle to be -0.6～-0.9MPa, and the reaction is continued When the torque reaches 60-100Nm, modified nylon is obtained;

Wherein, the diamine monomer is selected from one of pentamethylene diamine, hexamethylene diamine, decanediamine and dodecanediamine; the aromatic dibasic acid monomer is selected from terephthalic acid, isophthalic acid and A kind of in 2,6-naphthalenedicarboxylic acid; The third monomer is caprolactam or adipic acid; Melt viscosity modifier is selected from isophthalic acid, 1,4-cyclohexanedicarboxylic acid, methylcyclohexane One of diamine, 4,4'-diaminodicyclohexylmethane and 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane; the molecular weight regulator is selected from formic acid, acetic acid, benzene One of formic acid and stearic acid.

This is beneficial to reduce the viscosity of the obtained modified nylon and make it have higher mechanical properties, such as tensile strength, flexural strength, etc., and also help to make it have higher melting point, decomposition temperature, etc., and high temperature resistance.

In the present invention, the diamine monomer is selected from one of pentamethylenediamine, hexamethylenediamine, decanediamine and dodecanediamine; preferably, it is selected from pentamethylenediamine, hexamethylenediamine and decanediamine one, more preferably selected from hexylene diamine or decanediamine.

The aromatic dibasic acid monomer can be selected from one of terephthalic acid, isophthalic acid and 2,6-naphthalenedicarboxylic acid, preferably selected from terephthalic acid or 2,6-naphthalenedicarboxylic acid, more Preferred is terephthalic acid. The third monomer may be caprolactam or adipic acid, preferably caprolactam.

The melt viscosity modifier may be selected from isophthalic acid, 1,4-cyclohexanedicarboxylic acid, methylcyclohexanediamine, 4,4'-diaminodicyclohexylmethane and 3,3'-dimethyl One of yl-4,4'-diaminodicyclohexylmethane; preferably selected from isophthalic acid, methylcyclohexanediamine or 1,4-cyclohexanedicarboxylic acid; more preferably isophthalic acid Diformic acid. The inventor believes that the addition of the melt viscosity modifier can reduce the regularity of the chain segment, increase the shear sensitivity of the copolymer, improve the high temperature fluidity, and effectively solve the problem of large melt viscosity, uneven mixing, mass transfer and heat transfer in the later stage of the direct polycondensation reaction. The problem of poor effect; it can effectively reduce the melt viscosity in the later stage of the reaction, and ensure uniform stirring and smooth discharge in the vacuum polycondensation stage. Moreover, controlling the melt viscosity modifier within a specific ratio range can be beneficial to make the obtained modified nylon not reduce mechanical properties, have higher strength, and better high temperature resistance, such as higher melting point and decomposition temperature. The prepared high temperature resistant modified nylon is more suitable for complex structure and thin wall injection molding.

The molecular weight regulator is selected from one of formic acid, acetic acid, benzoic acid and stearic acid, preferably selected from benzoic acid or stearic acid, more preferably benzoic acid.

According to a preferred embodiment of the present invention, the diamine monomer is hexamethylene diamine, the aromatic dibasic acid monomer is terephthalic acid, the third monomer is caprolactam, and the melt viscosity modifier is isophthalic acid, The molecular weight regulator is benzoic acid.

The catalyst is preferably a mixture consisting of phosphoric acid, sodium dihydrogen phosphate and sodium hypophosphite, and the weight ratio of the three is 1-3:1-4:2-7, preferably 2-3:2-4:2-6 . This is beneficial to ensure uniform catalytic effect in each stage of the direct polycondensation.

Adjuvants include stabilizers and/or lubricants. In certain embodiments, the adjuvant is a lubricant. The stabilizer is selected from one or more of light stabilizer SEED, ultraviolet absorber UV3346, antioxidant 1098, antioxidant 626, preferably, the stabilizer is selected from light stabilizer SEED, ultraviolet absorber UV3346, antioxidant One of the antioxidant 1098 and the antioxidant 626. The lubricant can be those known in the art, preferably, the lubricant is silicone oil. The water can be deionized water, distilled water, purified water; preferably deionized water.

In the present invention, the weight ratio of diamine monomer, aromatic dibasic acid monomer, third monomer, melt viscosity modifier, molecular weight modifier, catalyst, stabilizer, lubricant and water can be 89～ 105:110～186.5:24～66:11～22:2～4:5～15:3～9:2～9:106～130, preferably 89～100:115～170:30～66:11～ 18:2～4:7～15:3～9:2～9:106～125, more preferably 89～100:115～145:30～65:11～16:2～4:9～14:3 ～9:2～9:106～125.

In step (1), the inert gas can be selected from one or more of nitrogen, argon or helium, preferably nitrogen, argon or helium, more preferably nitrogen. The inert gas can be used to replace the air in the reactor for 3 to 5 times to eliminate the interference of oxygen, and then the inert gas of 0.9 to 1.2 MPa can be filled to increase the solubility of the monomer and prevent the volatilization of the diamine monomer.

In step (2), the first mixture is reacted at 55-95° C. for 0.5-2 h, preferably, the first mixture is reacted at 60-90° C. for 0.5-1 h.

Then, the reaction is performed at 115-165° C. for 0.5-3 h, preferably, the reaction is performed at 120-160° C. for 0.5-2 h to obtain a second mixture. The inventor found that, on the one hand, this can facilitate the formation of salts between the diamine monomer and the aromatic dibasic acid monomer, and prevent the volatilization of the diamine monomer; Mixing, make the copolymer segment distribution more uniform, and give full play to the role of the copolymer viscosity modifier.

In step (3), the second mixture is reacted at 190-215°C and 1.2-1.6MPa for 0.5-2h to obtain the first prepolymer; in this step, the reaction temperature is preferably 190-210°C, and the reaction pressure is preferably 1.3～1.5MPa, the reaction time is preferably 0.5～1h. This facilitates the prepolymerization of the third monomer.

The first prepolymer is reacted at 210-255°C and 1.8-2.2MPa for 2-5h to obtain the second prepolymer; in this step, the reaction temperature is preferably 210-250°C, and the reaction pressure is preferably 1.8-2.1MPa , the reaction time is preferably 2 to 4 hours, and the gas can be properly vented during the process, which is beneficial to prepolymerize the diamine monomer and the aromatic dibasic acid monomer and copolymerize with the third monomer.

In step (4), the temperature is controlled to gradually increase the temperature while slowly degassing. The temperature is raised to 290-325°C within 2-5h and exhausted to normal pressure; in the process, the exhausting rate is adjusted by collecting the discharged condensed water. Preferably, the temperature is raised to 290-320° C. within 2-4 hours and exhausted to normal pressure. In the present invention, the water content in the kettle is judged by combining the relationship between the temperature in the kettle and the saturated vapor pressure in the kettle to further obtain the reaction degree, and the temperature and the degassing rate are adjusted in time to ensure that the reaction balance of the polycondensation reaction moves slowly and forwardly, and the reaction degree is uniform increase, keeping the molecular weight uniform.

Then vacuumize at a constant temperature of 290-320°C. Evacuate until the degree of vacuum in the reaction kettle is -0.6～-0.9MPa, and continue to react for 5～15min until the torque reaches 60～100Nm to obtain modified nylon. Preferably, the reaction is continued for 5-10 min until the torque reaches 70-90 Nm.

In the present invention, after the torque reaches the set requirement, stop stirring and fill with nitrogen to restore normal pressure, discharge, water-cool, cut into pellets and dry to obtain modified nylon.

According to the preparation method of the present invention, preferably:

The aromatic dibasic acid monomer is selected from the one in terephthalic acid and 2,6-naphthalenedicarboxylic acid;

The third monomer is caprolactam;

The melt viscosity modifier is selected from isophthalic acid, methylcyclohexanediamine or 1,4-cyclohexanedicarboxylic acid;

The molecular weight regulator is selected from one of benzoic acid and stearic acid.

According to the preparation method of the present invention, preferably:

The aromatic dibasic acid monomer is terephthalic acid;

The melt viscosity modifier is isophthalic acid;

The molecular weight regulator is benzoic acid.

According to the preparation method of the present invention, preferably:

The adjuvants include stabilizers and/or lubricants;

The weight ratio of the diamine monomer, aromatic dibasic acid monomer, third monomer, melt viscosity regulator, molecular weight regulator, catalyst, stabilizer, lubricant and water is 89～105:110～ 186.5:24～66:11～22:2～4:5～15:3～9:2～9:106～130. This is beneficial to obtain copolymer-modified nylon with high temperature resistance, high strength and low relative viscosity.

In the present invention, Zhongwang ISV-400 automatic viscometer is used to measure the relative viscosity of the copolymer, the solvent is concentrated sulfuric acid, the solution concentration is 0.1 g/dL, and the temperature is 25°C. The relative viscosity of the obtained copolymer-modified nylon is 2.0 to 2.5, preferably 2.0 to 2.4.

According to the preparation method of the present invention, preferably, the catalyst is composed of phosphoric acid, sodium dihydrogen phosphate and sodium hypophosphite, and the weight ratio of the three is 1-3:1-4:2-7. This is beneficial to the uniformity of catalysis in each stage of polycondensation.

According to the preparation method of the present invention, preferably, the stabilizer is selected from one or more of light stabilizer SEED, ultraviolet absorber UV3346, antioxidant 1098, and antioxidant 626.

According to the preparation method of the present invention, preferably, in step (4), the reaction is continued for 5-10 min until the torque reaches 70-90 Nm. This is beneficial to make the obtained modified nylon have higher strength and high temperature resistance.

The modified nylon of the present invention has better high temperature resistance, higher melting point and thermal decomposition temperature, lower relative viscosity, and can maintain better mechanical properties at the same time, and has higher tensile strength and flexural strength. The preparation method of the invention has stable process, low melt viscosity in the late stage of polymerization, easy stirring and smooth discharge, which is favorable for industrial production. Further, in the preparation method of the present invention, the diamine monomer, the aromatic dibasic acid monomer, the third monomer, the melt viscosity regulator, the molecular weight regulator, etc. are controlled within a specific ratio range, which will help to improve the The high temperature resistance of the obtained modified nylon product can reduce the viscosity of the product, improve the fluidity, and does not reduce the strength.

Description of drawings

FIG. 1 is a schematic diagram showing the results of the relative viscosity of nylons obtained in Examples 1 to 3 and Comparative Example 1 of the present invention.

2 is a schematic diagram showing the results of the melt flow rates of nylons obtained in Examples 1 to 3 and Comparative Example 1 of the present invention.

Detailed ways

The present invention will be further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

The analysis or testing methods are described below:

(1) Preparation of samples

Test specimens for tensile, flexural and impact properties were prepared according to GB/T 9352-2008 "Compression molding of plastic thermoplastic material samples". First, the prepared modified nylon resin was vacuum-dried at 100 °C for 6 h, and the splines were injected by a WZS10 injection molding machine. The barrel temperature was set to 20 °C above the melting point, the mold temperature was 80 °C, and the injection pressure was 7 MPa.

(2) Thermodynamic properties test

The melting point of the sample was measured by a NETZSCH DSC 200F3 differential scanning calorimeter. Under a nitrogen atmosphere, the temperature was raised to 350°C at a heating rate of 20°C/min, kept at a constant temperature for 5 minutes, the thermal history was eliminated, and then the temperature was lowered at a rate of 10°C/min. Cool down to 50°C, and finally rise to 350°C at a heating rate of 10°C/min;

A TA TGA 5500 thermogravimetric analyzer was used to determine the thermal decomposition temperature of the sample in a nitrogen atmosphere, with a heating rate of 10°C/min and a temperature range of 50 to 700°C.

(3) Mechanical property test

Instron 5567 universal testing machine was used to measure the tensile and flexural properties of different strips. The tensile rate was set to 5mm/min, the temperature was 25°C; the bending rate was 2mm/min, the span was 64mm, The deflection was 6% and the temperature was 25°C.

(4) Liquidity Characterization

The relative viscosity of different samples was measured by Zhongwang ISV-400 automatic viscometer. The solvent was concentrated sulfuric acid, the solution concentration was 0.1 g/dL, and the temperature was 25 °C.

The melt flow rate of different samples was measured by Veken WKT-400 melt index meter, the test condition was 320 °C, and the load was 2.16 Kg.

In the examples and comparative examples of the present invention, unless otherwise specified, the parts are calculated as parts by weight.

Examples 1-3 and Comparative Examples 1-5

Feed according to the feed table in Table 1:

(1) Add hexamethylenediamine, terephthalic acid, isophthalic acid, benzoic acid, caprolactam, phosphoric acid, sodium hypophosphite monohydrate, disodium hydrogen phosphate, and silicone oil to deionized water to disperse, to form slurry raw materials , and transferred to the reaction kettle; use inert gas to replace the air in the reaction kettle 3 times to eliminate the interference of oxygen, and finally fill with 0.9MPa inert gas to increase the solubility of the monomer and prevent the volatilization of the diamine; obtain the first mixture .

(2) Turn on stirring and heat up, react the first mixture at 100 rpm and 80° C. for 1 h to make the diamine and the dibasic acid form salt; mixture;

(3) The temperature was raised to 210°C again, and the exhaust gas was adjusted appropriately, the second mixture was reacted at 210°C and 1.5MPa for 1 h, and the third monomer was prepolymerized to obtain the first prepolymer; the temperature was continued to rise to 220°C, The first prepolymer was reacted at 220° C. and 1.9 MPa for 2 h to obtain the second prepolymer;

(4) Gradually increase the temperature by controlling the heating rate, and at the same time, open the pressure relief valve to slowly release the air, raise the temperature to 310 °C within 4 hours, and release the air to normal pressure. During the period, the air release rate is adjusted by calculating the ratio of the collected and discharged condensed water to the added water. , make the balance move stably and forwardly, and obtain a high temperature resistant prepolymer with uniform molecular chain distribution; at a constant temperature, the vacuum is slowly pumped at a rate of 0.01MPa/min until the vacuum degree in the reactor reaches -0.8MPa, and the reaction is continued for 5-10min to torque When it reaches 80Nm, stop stirring, fill with nitrogen to restore normal pressure, discharge, water-cool, cut into pellets, and dry to obtain modified nylon; wherein, PA6 in the modified nylon product accounts for 40%. The products of Examples 1 to 3 are designated as PA6T/6I/6. The test results of thermodynamic and mechanical properties are shown in Table 2. The test results of melt index and relative viscosity of Examples 1 to 3 and Comparative Example 1 are shown in FIGS. 1 and 2 .

Comparative Example 6

Except for the following settings, the rest is the same as Example 1:

Step (2): turn on stirring and raise the temperature, react the raw materials at a constant temperature of 100 rpm and 80° C. for 1 h to obtain the first mixture and directly raise the temperature to 210° C. for prepolymerization. The test results are shown in Table 2.

Table 1 Feeding table

Table 2 Test results

From the comparison of Examples 1 to 3 and Comparative Example 1, it can be seen that the melt viscosity modifier isophthalic acid and the molecular weight modifier benzoic acid are not added, and the amount of aromatic dibasic acid is relatively increased, and the thermodynamic properties of the obtained product nylon include: Melting point, crystallization temperature, decomposition temperature are reduced, and mechanical properties including tensile strength, flexural strength, and flexural modulus are also reduced. The reason may be that the melting point of linear aliphatic nylon PA6 is low, the high segment regularity of the copolymer component is worse, and the crystallinity is low, so the melting temperature will decrease. Decomposition temperature and tensile strength decreased. Examples 1-3 show that the higher the aromatic ring content in the copolymer, the higher the melting point and the better the heat resistance. Therefore, the regulation of modified nylon with different properties can be realized by adjusting the ratio of aromatic dicarboxylic acid and aliphatic comonomer. for applications in different fields.

From the comparison of Examples 1 to 3 and Comparative Example 2, it can be seen that only the melt viscosity modifier isophthalic acid can be used as the third comonomer to adjust the melting point of the modified nylon. Due to its high rigidity and steric hindrance, its comprehensive performance It is weaker than the ternary copolymer material, but its segment regularity is poor, the obtained molecular crystallinity is low, and a relatively transparent product can be obtained.

From the comparison of Examples 1 to 3 and Comparative Examples 3 to 5, it can be known that if the dosage ratio of the aromatic dibasic acid monomer terephthalic acid and the melt viscosity modifier isophthalic acid is not within the scope of the weight ratio of the present invention, then The thermodynamic properties of the obtained nylon will decrease, including melting point, crystallization temperature, and decomposition temperature, and the tensile strength in mechanical properties will decrease, but the flexural strength and flexural modulus will not decrease. This may be because the excessive introduction of asymmetric structure reduces the melting point and tensile strength of the resulting product, because the complex conformational transition and the irregularity of the chain segments reduce the crystallinity of the resulting nylon, while the increase in flexural strength may be a Because more conformational transition forms enable the resulting nylon molecular chain to stretch under stretching.

From the comparison of Example 1 and Comparative Example 6, it can be seen that directly heating up and performing polycondensation after salification at 80 ° C will cause a decrease in the overall performance of the product. The large difference in reactivity results in the uneven distribution of molecular chains. The decrease in mechanical properties may be due to the fact that part of the diamine is volatilized by direct prepolymerization after salt formation, which affects the molar ratio of monomers and reduces the molecular weight.

Example 4

The only difference from Example 1 is that 14.63 parts of 1,4-cyclohexanedicarboxylic acid were used instead of 14.30 parts of isophthalic acid. The product of Example 4 is designated PA6T/6C/6. The test results are shown in Table 3.

table 3

The present invention is not limited to the above-mentioned embodiments, and any modifications, improvements and substitutions that can be conceived by those skilled in the art without departing from the essence of the present invention fall into the scope of the present invention.

Claims (10)

1. a modified nylon, is characterized in that, has the structure shown in formula (I):

In formula (I), a is 5, 6, 10 or 12; x, y, and z are the number of repeating units, respectively, and are integers from 1 to 20; R ₁ is an aromatic group, which is selected from one of the following groups:

R ₂ is selected from one of the following groups:

R ₃ is selected from one of the following groups:

wherein R ₁ and R ₃ are different. 2. modified nylon according to claim 1, is characterized in that: R ₁ is selected from one of the following groups:

_R2 is

R ₃ is selected from one of the following groups:

3. modified nylon according to claim 1, is characterized in that: _R1 is

_R3 is

4. the preparation method of modified nylon as described in any one of claim 1～3, is characterized in that, comprises the steps: (1) Under the protection of inert gas, add diamine monomer, aromatic dibasic acid monomer, third monomer, melt viscosity regulator, molecular weight regulator, catalyst, auxiliary agent and water into the reaction kettle , to obtain the first mixture; (2) react the first mixture at 55-95°C for 0.5-2h; then react at 115-165°C for 0.5-3h; obtain the second mixture; (3) react the second mixture at 190-215°C and 1.2-1.6MPa for 0.5-2h to obtain the first prepolymer; react the first prepolymer at 210-255°C and 1.8-2.2MPa for 2- 5h, obtain the second prepolymer; (4) the second prepolymer is heated to 290～325 ℃ in 2～5h, and the reaction kettle is exhausted to normal pressure; then the vacuum is evacuated until the vacuum degree in the reaction kettle is -0.6～-0.9MPa, and the reaction is continued When the torque reaches 60-100Nm, modified nylon is obtained; Wherein, the diamine monomer is selected from the one in pentamethylene diamine, hexamethylene diamine, decanediamine and dodecanediamine; Wherein, the aromatic dibasic acid monomer is selected from the one in terephthalic acid, isophthalic acid and 2,6-naphthalenedicarboxylic acid; Wherein, the third monomer is caprolactam or adipic acid; Wherein, the melt viscosity modifier is selected from isophthalic acid, 1,4-cyclohexanedicarboxylic acid, methylcyclohexanediamine, 4,4'-diaminodicyclohexylmethane and 3,3'-dicyclohexylmethane A kind of methyl-4,4'-diaminodicyclohexylmethane; Wherein, the molecular weight regulator is selected from one of formic acid, acetic acid, benzoic acid and stearic acid. 5. preparation method according to claim 1, is characterized in that: The diamine monomer is selected from the one in pentamethylene diamine, hexamethylene diamine and decanediamine; The aromatic dibasic acid monomer is selected from the one in terephthalic acid and 2,6-naphthalenedicarboxylic acid; The third monomer is caprolactam; The melt viscosity modifier is selected from isophthalic acid, methylcyclohexanediamine or 1,4-cyclohexanedicarboxylic acid; The molecular weight regulator is selected from one of benzoic acid and stearic acid. 6. preparation method according to claim 1, is characterized in that: The diamine monomer is hexamethylenediamine or decanediamine; The aromatic dibasic acid monomer is terephthalic acid; The melt viscosity modifier is isophthalic acid; The molecular weight regulator is benzoic acid. 7. preparation method according to claim 1, is characterized in that: The adjuvants include stabilizers and/or lubricants; The weight ratio of the diamine monomer, aromatic dibasic acid monomer, third monomer, melt viscosity regulator, molecular weight regulator, catalyst, stabilizer, lubricant and water is 89～105:110～ 186.5:24～66:11～22:2～4:5～15:3～9:2～9:106～130. 8. preparation method according to claim 7 is characterized in that, described catalyst is made up of phosphoric acid, sodium dihydrogen phosphate and sodium hypophosphite, and the weight ratio of the three is 1～3:1～4:2～7 . 9 . The preparation method according to claim 7 , wherein the stabilizer is selected from one or more of light stabilizer SEED, ultraviolet absorber UV3346, antioxidant 1098, and antioxidant 626. 10 . 10 . The preparation method according to claim 1 , wherein, in step (4), the reaction is continued for 5-10 min until the torque reaches 70-90 Nm. 11 .

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