A high viscosity polyamide 66 resin, its preparation method and use

Abstract

The application provides a high-viscosity polyamide 66 resin and a preparation method and application thereof. The high-viscosity polyamide 66 resin is obtained by solid-phase polymerization of a low-viscosity polyamide 66 resin, the content of terminal amino groups in the low-viscosity polyamide 66 resin is 14-60 mmol / kg, and the content of terminal carboxyl groups is 60-80 mmol / kg. By controlling the content of terminal amino groups and terminal carboxyl groups in the low-viscosity polyamide 66 resin and making the two have a certain difference, the high-viscosity polyamide 66 resin with high relative viscosity, low gel content and excellent appearance is successfully obtained by using the solid-phase polymerization method.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of polyamides, and particularly relates to a high-viscosity polyamide 66 resin and a preparation method and application thereof. BACKGROUND

[0002] Polyamide 66 resin has the outstanding characteristics of high strength, light weight, wear resistance, aging resistance, etc., and especially high-viscosity polyamide has the performance of higher strength, high wear resistance and fatigue resistance, and is mainly used in the industrial field with higher requirements for material strength.

[0003] At present, the melt polymerization method can only produce low-viscosity and medium-viscosity polyamide 66 resin, but low-viscosity and medium-viscosity polyamide 66 directly used for extrusion products (such as plates and pipes) is prone to melt falling or flow casting, which limits the application range of polyamide 66 resin; therefore, it is necessary to increase the viscosity of polyamide 66 resin and reduce the viscosity fluctuation of polyamide 66 resin when it is retained in the screw, so as to solve the problems of melt falling and flow casting.

[0004] Commonly used methods for increasing the viscosity of polyamide 66 need to use a solid-phase polymerization process, and the chips are heated at high temperature in a nitrogen atmosphere or vacuum condition to promote the increase of the viscosity. CN114437342A discloses a preparation method of high-viscosity polyamide resin, and the preparation steps are as follows: step (1) a salting step to obtain polyamide salt solution A and functional monomer salt solution B; mixing the polyamide salt solution A and the functional monomer salt solution B, evaporating and concentrating to obtain polyamide salt solution C; step (2) a prepolymerization step, continuously reacting the polyamide salt solution C above the polymer melting point to obtain prepolymer D; step (3) a post-polymerization step, continuously reacting the prepolymer D to obtain polyamide melt, and cutting and cooling to obtain polyamide solid particles E; and step (4) a solid-phase polymerization step, controlling the relative viscosity of the polyamide solid particles E to increase to 4.2-5.7, and obtaining high-viscosity polyamide resin after cooling; however, compared with other polyamide resins, polyamide 66 resin is prone to thermal degradation and three-dimensional structuring, because the two terminal amino groups in the polyamide 66 resin are prone to condensation to form bis(ω-aminohexyl)amine under the condition of continuous high temperature, and then a three-functional amine condensation reaction occurs, finally forming a gel, resulting in poor appearance of the product.

[0005] Therefore, in order to solve the above technical problems, it is urgent to develop a high-viscosity polyamide 66 resin with low gel content and good appearance. SUMMARY

[0006] In view of the deficiencies of the prior art, the present application aims to provide a high-viscosity polyamide 66 resin and a preparation method and application thereof, wherein the high-viscosity polyamide 66 resin is obtained by solid-phase polymerization of a low-viscosity polyamide 66 resin, the content of terminal amino groups and terminal carboxyl groups in the low-viscosity polyamide 66 resin is controlled to have a certain difference, and the high-viscosity polyamide 66 resin with high relative viscosity, low gel content and good appearance is successfully obtained by the solid-phase polymerization method.

[0007] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0008] In a first aspect, the present application provides a high-viscosity polyamide 66 resin, which is obtained by solid-phase polymerization of a low-viscosity polyamide 66 resin.

[0009] The content of terminal amino groups in the low-viscosity polyamide 66 resin is 14-60 mmol / kg, and the content of terminal carboxyl groups is 60-80 mmol / kg.

[0010] The content of terminal amino groups in the low-viscosity polyamide 66 resin can be 16 mmol / kg, 18 mmol / kg, 20 mmol / kg, 22 mmol / kg, 24 mmol / kg, 26 mmol / kg, 28 mmol / kg, 31 mmol / kg, 32 mmol / kg, 33 mmol / kg, 34 mmol / kg, 35 mmol / kg, 36 mmol / kg, 37 mmol / kg, 38 mmol / kg or 39 mmol / kg, etc.

[0011] The content of terminal carboxyl groups in the low-viscosity polyamide 66 resin can be 60 mmol / kg, 62 mmol / kg, 64 mmol / kg, 66 mmol / kg, 68 mmol / kg, 70 mmol / kg or 72 mmol / kg, etc.

[0012] The polyamide 66 resin is prepared by condensation polymerization of adipic acid and hexamethylene diamine, and generally, the acid diamine molar ratio of the raw materials is required to be 1:1 to ensure the smooth growth of the molecular weight of the polyamide 66 resin, and the acid diamine molar ratio of the obtained polyamide 66 resin is also 1:1. However, the inventors of the present application have found that the upper limit of the viscosity growth of the polyamide 66 resin under the above conditions is too high, which is not conducive to the subsequent solid-phase polymerization for viscosity increase. Therefore, by controlling the content of the terminal amino group in the low-viscosity polyamide 66 resin to be 14-60 mmol / kg and the content of the terminal carboxyl group to be 60-80 mmol / kg, the relative content of the terminal amino group in the low-viscosity polyamide 66 resin is relatively low, and there is a certain difference from the terminal carboxyl group, which ensures sufficient reaction raw materials, and the relatively low content of the terminal amino group can reduce the probability of the condensation of two terminal amino groups to form bis(ω-aminohexyl)amine under the condition of continuous high temperature, and then the condensation reaction of trifunctional amine to form gel, thereby successfully obtaining a high-viscosity polyamide 66 resin with relatively high viscosity, low gel content and good appearance.

[0013] It should be noted that the "high-viscosity polyamide 66 resin" in the present application refers to a polyamide 66 resin with a relative viscosity of 4.2-5.35.

[0014] Preferably, the relative viscosity of the high-viscosity polyamide 66 resin is 4.75-5.35, for example, 4.8, 5, 4.9, 4.95, 5, 5.05, 5.1, 5.15, 5.2, 5.25 or 5.3, etc.

[0015] Preferably, the content of the terminal amino group in the high-viscosity polyamide 66 resin is 5-15 mmol / kg, for example, 6 mmol / kg, 7 mmol / kg, 8 mmol / kg, 9 mmol / kg, 10 mmol / kg, 11 mmol / kg, 12 mmol / kg, 13 mmol / kg or 14 mmol / kg, etc.

[0016] Preferably, the melt index of the high-viscosity polyamide 66 resin is ≤15 g / 10 min, for example, 14 g / 10 min, 13 g / 10 min, 12 g / 10 min, 11 g / 10 min, 10 g / 10 min, 9 g / 10 min, 8 g / 10 min or 7 g / 10 min, etc.

[0017] Preferably, the content of the terminal amino group in the low-viscosity polyamide 66 resin is 30-40 mmol / kg.

[0018] Preferably, the content of the terminal carboxyl group in the low-viscosity polyamide 66 resin is 64-74 mmol / kg.

[0019] Preferably, the difference between the content of terminal carboxyl groups and terminal amine groups in the low-viscosity polyamide 66 resin is 24-44 mmol / kg, such as 26 mmol / kg, 28 mmol / kg, 30 mmol / kg, 32 mmol / kg, 34 mmol / kg, 36 mmol / kg, 38 mmol / kg, 40 mmol / kg or 42 mmol / kg, etc.; further limiting the difference between the content of terminal carboxyl groups and the content of terminal amine groups in the low-viscosity polyamide 66 resin within the above range can make the content of gels in the obtained high-viscosity polyamide 66 resin lower.

[0020] Preferably, the relative viscosity of the low-viscosity polyamide 66 resin is 2.8-3.2, such as 2.85, 2.9, 2.95, 3, 3.05, 3.1 or 3.15, etc.

[0021] Preferably, the raw materials for preparing the low-viscosity polyamide 66 resin include polyamide 66 salt, catalyst and linear dibasic acid.

[0022] As a preferred technical solution of the present application, the present application further limits the raw materials for preparing the low-viscosity polyamide 66 resin to include polyamide 66 salt, catalyst and linear dibasic acid; firstly, adding linear dibasic acid can be used to adjust the relative content of terminal amino groups and terminal carboxyl groups in the low-viscosity polyamide 66 resin formed after prepolymerization of polyamide 66 salt, so that the two have a certain difference, in order to facilitate the subsequent preparation of high-viscosity polyamide 66 resin; on the one hand, if branched dibasic amine is introduced, the content of terminal amino groups in the polyamide 66 resin will be too high, and two terminal amino groups will condense to form bis(ω-aminohexyl)amine under continuous high temperature conditions, which is prone to condensation reaction of trifunctional amine, resulting in the formation of gels; on the other hand, if branched dibasic acid is introduced, although the content of terminal carboxyl groups in the low-viscosity polyamide 66 resin can be increased, but the branched structure end group structure will be introduced, which has a large steric hindrance, limiting the chain segment movement of the molecular chain during solid-phase polymerization, resulting in a wide molecular weight distribution of the finished product, which cannot be applied to extruded products (such as plates, pipes); secondly, since the polycondensation reaction of polyamide 66 resin is reversible and the reaction rate is slow, an appropriate amount of catalyst needs to be added to quickly proceed in the positive direction, and at the same time, adding an appropriate amount of catalyst can increase the reaction rate, speed up the viscosity growth, shorten the residence time of polyamide 66 resin under high temperature conditions, and improve its appearance.

[0023] Preferably, the raw materials for preparing the polyamide 66 salt include hexamethylene diamine and adipic acid.

[0024] Preferably, the catalyst includes any one or a combination of at least two of sodium hypophosphite, sodium phenyl hypophosphite or zinc hypophosphite.

[0025] Preferably, the content of phosphorus in the raw material for preparing the low-viscosity polyamide 66 resin is 5-25 mg / kg, for example 7 mg / kg, 9 mg / kg, 11 mg / kg, 13 mg / kg, 15 mg / kg, 17 mg / kg, 19 mg / kg, 21 mg / kg or 23 mg / kg, etc.

[0026] Preferably, the linear dibasic acid is a linear dibasic acid with a carbon atom number of 4-12 (for example 5, 6, 7, 8, 9, 10 or 11, etc.).

[0027] Preferably, the mass percentage content of linear dibasic acid in the raw material for preparing the low-viscosity polyamide 66 resin is 0.1-0.3%, for example 0.12%, 0.14%, 0.16%, 0.18%, 0.2%, 0.22%, 0.24%, 0.26% or 0.28%, etc.

[0028] Preferably, the low-viscosity polyamide 66 resin is prepared by a preparation method comprising: polymerizing polyamide 66 salt, linear dibasic acid and catalyst to obtain the low-viscosity polyamide 66 resin.

[0029] In the second aspect, the present application provides a preparation method of the high-viscosity polyamide 66 resin as described in the first aspect, which comprises: solid-phase polymerizing the low-viscosity polyamide 66 resin to obtain the high-viscosity polyamide 66 resin.

[0030] Preferably, the solid-phase polymerization is performed under a vacuum degree < 200 Pa (for example 180 Pa, 160 Pa, 140 Pa, 120 Pa, 100 Pa, 80 Pa or 60 Pa, etc.).

[0031] Preferably, the solid-phase polymerization is performed under the condition of first heating and then cooling.

[0032] Preferably, the temperature after heating is 160-190°C, for example 165°C, 170°C, 175°C, 180°C or 185°C, etc.

[0033] Preferably, the heating rate is 8-12°C / min, for example 8.5°C / min, 9°C / min, 9.5°C / min, 10°C / min, 10.5°C / min, 11°C / min or 11.5°C / min, etc.

[0034] Preferably, the holding time after heating is 12-24 h, for example 14 h, 16 h, 18 h, 20 h or 22 h, etc.

[0035] Preferably, the temperature after cooling is room temperature.

[0036] Preferably, the rate of said cooling is 8-12°C / min, such as 8.5°C / min, 9°C / min, 9.5°C / min, 10°C / min, 10.5°C / min, 11°C / min or 11.5°C / min, etc.

[0037] In a third aspect, the present application provides a polyamide 66 resin composition comprising the high viscosity polyamide 66 resin according to the first aspect and additives.

[0038] In a fourth aspect, the present application provides use of the high viscosity polyamide 66 resin according to the first aspect or the polyamide 66 resin composition according to the third aspect in a plate or a pipe.

[0039] Compared with the prior art, the present application has the following beneficial effects:

[0040] The high viscosity polyamide 66 resin provided by the present application is obtained by solid phase polymerization of a low viscosity polyamide 66 resin, wherein the content of terminal amino groups in the low viscosity polyamide 66 resin is 14-60 mmol / kg, and the content of terminal carboxyl groups is 60-80 mmol / kg; by controlling the content of terminal amino groups and terminal carboxyl groups in the low viscosity polyamide 66 resin so that they have a certain difference, and using the solid phase polymerization method, a high viscosity polyamide 66 resin with relatively high viscosity, low gel content and excellent appearance is successfully obtained. DETAILED DESCRIPTION

[0041] The technical solutions of the present application will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only to help understand the present application, and should not be regarded as specific limitations on the present application.

[0042] Example 1

[0043] A high viscosity polyamide 66 resin, the preparation method thereof comprising the following steps:

[0044] (1) 14 kg (99 mol) of adipic acid and 11 kg (99 mol) of hexamethylene diamine are sequentially added into 25 kg of desalted water, and reacted at 70°C for 30 min, and then recrystallized and dried to obtain a dry salt of nylon 66;

[0045] (2) 25 kg of the dry salt of nylon 66 obtained in step (1), 55 g of adipic acid and 1.3 g of sodium phenylphosphinate are dissolved in desalted water to obtain a polyamide 66 salt solution with a mass percentage of 56%;

[0046] (3) the polyamide 66 salt solution obtained in step (2) is concentrated at 152°C for 30 min to obtain a concentrated polyamide 66 salt solution with a mass percentage of 80%; the concentrated polyamide 66 salt solution is then heated to 220°C, the pressure is increased to 1.85 MPa, the pressure is kept stable, the temperature of the reactants is gradually increased to 260°C, then the pressure is slowly decreased to normal pressure, the temperature of the reactants is synchronously increased to 275°C, and after 30 min of reaction, the reactants are cooled and granulated to obtain a low-viscosity polyamide 66 resin;

[0047] (4) under vacuum, the low-viscosity polyamide 66 resin obtained in step (3) is first heated at a heating rate of 10°C / min from room temperature to 175°C and kept at 175°C for 12.5 h, and then cooled at a cooling rate of 10°C / min to 60°C to obtain the high-viscosity polyamide 66 resin.

[0048] Example 2

[0049] A high-viscosity polyamide 66 resin, a preparation method thereof comprises the following steps:

[0050] (1) 14 kg (99 mol) of adipic acid and 11 kg (99 mol) of hexamethylene diamine are sequentially added to 25 kg of desalted water, reacted at 70°C for 30 min, and then recrystallized and dried to obtain a dry nylon 66 salt;

[0051] (2) 25 kg of the dry nylon 66 salt obtained in step (1), 43 g of adipic acid, and 0.72 g and 1.3 g of sodium phenylphosphinate are added to desalted water to obtain a polyamide 66 salt solution with a mass percentage of 56%;

[0052] (3) the polyamide 66 salt solution obtained in step (2) is concentrated at 152°C for 30 min to obtain a concentrated polyamide 66 salt solution with a mass percentage of 80%; the concentrated polyamide 66 salt solution is then heated to 220°C, the pressure is increased to 1.85 MPa, the pressure is kept stable, the temperature of the reactants is gradually increased to 260°C, then the pressure is slowly decreased to normal pressure, the temperature of the reactants is synchronously increased to 275°C, and after 30 min of reaction, the reactants are cooled and granulated to obtain a low-viscosity polyamide 66 resin;

[0053] (4) under vacuum, the low-viscosity polyamide 66 resin obtained in step (3) is first heated at a heating rate of 9°C / min from room temperature to 180°C and kept at 180°C for 15 h, and then cooled at a cooling rate of 9°C / min to room temperature to obtain the high-viscosity polyamide 66 resin.

[0054] Example 3

[0055] A high-viscosity polyamide 66 resin, a preparation method thereof comprises the following steps:

[0056] (1) 14 kg (99 mol) adipic acid and 11 kg (99 mol) hexamethylene diamine were added into 25 kg of desalted water in turn, and reacted at 70 °C for 30 min, and then recrystallized and dried to obtain nylon 66 dry salt;

[0057] (2) 25 kg of the nylon 66 dry salt obtained in step (1), 70 g of adipic acid and 1.3 g of sodium phenylphosphinate were dissolved in desalted water to obtain a polyamide 66 salt solution with a mass percentage of 56%;

[0058] (3) The polyamide 66 salt solution obtained in step (2) was concentrated at 152 °C for 30 min to obtain a concentrated polyamide 66 salt solution with a mass percentage of 80%; then the concentrated polyamide 66 salt solution was heated to 220 °C, the pressure was increased to 1.85 MPa, the temperature of the reactants was gradually increased to 260 °C, then the pressure was slowly reduced to normal pressure, the temperature of the reactants was simultaneously increased to 275 °C, and after 30 min of reaction, the reactants were cooled and granulated to obtain a low-viscosity polyamide 66 resin;

[0059] (4) The low-viscosity polyamide 66 resin obtained in step (3) was first heated from room temperature to 160 °C at a heating rate of 11 °C / min, and then kept at 160 °C for 24 h, and then cooled to room temperature at a cooling rate of 11 °C / min to obtain the high-viscosity polyamide 66 resin.

[0060] Example 4

[0061] A high-viscosity polyamide 66 resin, which is only different from Example 1 in that the amount of adipic acid added in step (2) is 20 g, and the other substances, amounts and preparation methods refer to Example 1.

[0062] Example 5

[0063] A high-viscosity polyamide 66 resin, which is only different from Example 1 in that the amount of adipic acid added in step (2) is 80 g, and the other substances, amounts and preparation methods refer to Example 1.

[0064] Example 6

[0065] A high-viscosity polyamide 66 resin, which is only different from Example 1 in that equimolar succinic acid is used to replace adipic acid in step (2), and the other substances, amounts and preparation methods refer to Example 1.

[0066] Example 7

[0067] A high-viscosity polyamide 66 resin, which is only different from Example 1 in that equimolar dodecanedioic acid is used to replace adipic acid in step (2), and the other substances, amounts and preparation methods refer to Example 1.

[0068] Example 8

[0069] A high viscosity polyamide 66 resin, which is different from Example 1 only in that equimolar malonic acid is used to replace adipic acid in step (2), and other substances, amounts and preparation methods refer to Example 1.

[0070] Example 9

[0071] A high viscosity polyamide 66 resin, which is different from Example 1 only in that equimolar tridecanedioic acid is used to replace adipic acid in step (2), and other substances, amounts and preparation methods refer to Example 1.

[0072] Example 10

[0073] A high viscosity polyamide 66 resin, which is different from Example 1 only in that equimolar 2,2-dimethyl succinic acid is used to replace adipic acid in step (2), and other substances, amounts and preparation methods refer to Example 1.

[0074] Example 11

[0075] A high viscosity polyamide 66 resin, which is different from Example 1 only in that no sodium phosphite is added in step (2), and other substances, amounts and preparation methods refer to Example 1.

[0076] Comparative Example 1

[0077] A polyamide 66 resin, the preparation method thereof comprises the following steps:

[0078] (1) 14 kg (99 mol) of adipic acid and 11 kg (99 mol) of hexamethylene diamine are sequentially added into 25 kg of desalted water, and reacted at 70 °C for 30 min, and then recrystallized and dried to obtain a nylon 66 dry salt;

[0079] (2) The nylon 66 dry salt obtained in step (1) and 1.3 g of sodium phenylphosphinate are dissolved in desalted water to obtain a polyamide 66 salt solution with a mass percentage of 56%;

[0080] (3) The polyamide 66 salt solution obtained in step (2) is concentrated at 152 °C for 30 min to obtain a concentrated polyamide 66 salt solution with a mass percentage of 80%; then the concentrated polyamide 66 salt solution is heated to 220 °C, the pressure is increased to 1.85 MPa, the pressure is kept stable, the temperature of the reactants is gradually increased to 260 °C, then the pressure is slowly reduced to normal pressure, the temperature of the reactants is simultaneously increased to 275 °C, and after 30 min of reaction, cooling and granulation, a polyamide 66 resin is obtained.

[0081] Comparative Example 2

[0082] A polyamide 66 resin, a preparation method thereof comprises the following steps:

[0083] (1) 14 kg (99 mol) of adipic acid and 11 kg (99 mol) of hexamethylenediamine are sequentially added into 25 kg of desalted water, and reacted at 70℃ for 30 min to obtain dry salt of nylon 66;

[0084] (2) The dry salt of nylon 66 obtained in step (1) and 1.3 g of sodium phenylphosphinate are dissolved in desalted water to obtain a polyamide 66 salt solution with a mass percentage of 56%;

[0085] (3) The polyamide 66 salt solution obtained in step (2) is concentrated at 152℃ for 30 min to obtain a concentrated polyamide 66 salt solution with a mass percentage of 80%; then the concentrated polyamide 66 salt solution is heated to 220℃, the pressure is increased to 1.85 MPa, the temperature of the reactants is gradually increased to 260℃, then the pressure is slowly reduced to normal pressure, the temperature of the reactants is simultaneously increased to 275℃, and after 30 min of reaction, cooling and granulation are performed to obtain a low-viscosity polyamide 66 resin;

[0086] (4) The low-viscosity polyamide 66 resin obtained in step (3) is first heated from room temperature to 175℃ at a heating rate of 10℃ / min, and then heated at 175℃ for 12.5 h, and then cooled to 60℃ at a cooling rate of 10℃ / min to obtain the polyamide 66 resin.

[0087] Comparative Example 3

[0088] A high-viscosity polyamide 66 resin, which is only different from the polyamide 66 resin of Example 1 in that equimolar hexamethylenediamine is used to replace adipic acid in step (2), and other substances, amounts and preparation methods refer to those of Example 1.

[0089] Performance test:

[0090] (1) Terminal amino group content and terminal carboxyl group content: tested according to the test method provided in HG / T 4182-2012;

[0091] (2) Relative viscosity: tested according to the test method provided in GB / T 12006.1;

[0092] (3) Melt index: tested according to the test method provided in GB / T 3682.2;

[0093] (4) Viscosity after retention: tested according to the test method provided in GB / T 12006.1;

[0094] (5) Gel content: first, a certain mass M0 of the sample to be detected is dissolved in formic acid solution and placed in a water bath at 50℃ for 24h; then a suitable size of microporous filter membrane which has been treated (soaked in formic acid solution until the mass is constant) is selected, the minimum pore size is 0.22μm, and larger pore size filter membranes can also be used for fractional filtration, the mass of the filter membrane is recorded as M1; then install the sand core filtration device and the circulating water vacuum pump, prevent foreign matter pollution during the filtration process, and supplement a certain amount of formic acid several times when the filtrate liquid surface is low; finally, rinse with a certain amount of deionized water and anhydrous ethanol, remove the filter membrane and dry it to constant weight, the mass is recorded as M2; the gel content (M) is calculated according to G=(M2-M1) / M0x100%;

[0095] (6) Yellowing index: test according to the test method provided in GB / T 39822.

[0096] The polyamide 66 resins provided in Examples 1-11 and Comparative Examples 1-3 are tested according to the above test methods, and the test results are shown in Table 1:

[0097] Table 1

[0098]

[0099]

[0100] According to the data in Table 1, it can be seen that the high-viscosity polyamide resin with low gel content and excellent appearance is prepared by using specific raw material components and proportions;

[0101] Specifically, the high-viscosity polyamide 66 resins obtained in Examples 1-2 have a melt index of 8-30g / 10min, a residence viscosity of 112-254mL / g, a gel content of only 0.009-0.069%, and a yellowing index of-2-5;

[0102] Compared with Example 1, the high-viscosity polyamide 66 resins provided in Comparative Examples 1-3 have a relatively high relative viscosity, but their gel content and yellowing index are too high, indicating that the high-viscosity polyamide 66 resins provided in Comparative Examples 1-3 have poor appearance;

[0103] At the same time, by comparing the data of Examples 1, 4-5 and 8-11, it can be found that the type and content of linear dibasic acid in the preparation raw material of the low-viscosity polyamide 66 resin also have an adverse effect on the relative viscosity and gel content of the high-viscosity polyamide 66 resin obtained.

[0104] Applicant states that the present application illustrates a high viscosity polyamide 66 resin, its preparation method and application by the above-mentioned examples, but the present application is not limited to the above-mentioned examples, that is, it does not mean that the present application must rely on the above-mentioned examples to be implemented. The skilled in the art should understand that any improvement of the present application, equivalent replacement of each raw material of the product of the present application, addition of auxiliary ingredients, selection of specific mode, etc. fall within the protection scope and disclosure scope of the present application.

Claims

1. A high viscosity polyamide 66 resin characterized in that, The high-viscosity polyamide 66 resin is obtained by solid-phase polymerization of a low-viscosity polyamide 66 resin. The content of terminal amino groups in the low-viscosity polyamide 66 resin is 30-40 mmol / kg, and the content of terminal carboxyl groups is 64-74 mmol / kg. The difference between the content of terminal carboxyl groups and terminal amino groups in the low-viscosity polyamide 66 resin is 24-44 mmol / kg. The relative viscosity of the low-viscosity polyamide 66 resin is 2.8-3.

2. The raw materials for preparing the low-viscosity polyamide 66 resin include polyamide 66 salt, catalyst and linear dibasic acid. The linear dibasic acid is a linear dibasic acid with a carbon atom number of 4-12. The mass percentage content of linear dibasic acid in the raw materials for preparing the low-viscosity polyamide 66 resin is 0.1-0.3%.

2. The high viscosity polyamide 66 resin according to claim 1, characterized in that, The relative viscosity of the high-viscosity polyamide 66 resin is 4.75-5.

35.

3. The high viscosity polyamide 66 resin according to claim 1, characterized in that, The content of terminal amino groups in the high-viscosity polyamide 66 resin is 5-15 mmol / kg.

4. The high viscosity polyamide 66 resin of claim 1, wherein, The melt index of the high-viscosity polyamide 66 resin is ≤15 g / 10 min.

5. The high viscosity polyamide 66 resin of claim 1, wherein, The raw materials for preparing the polyamide 66 salt include hexanediamine and adipic acid.

6. The high viscosity polyamide 66 resin of claim 1, wherein, The catalyst includes any one or a combination of at least two of sodium hypophosphite, sodium phenylphosphinate or zinc hypophosphite.

7. The high viscosity polyamide 66 resin according to claim 1, wherein The content of phosphorus in the raw materials for preparing the low-viscosity polyamide 66 resin is 5-25 mg / kg.

8. The high viscosity polyamide 66 resin of claim 1, wherein, The low-viscosity polyamide 66 resin is prepared by a preparation method, which comprises polymerizing polyamide 66 salt, linear dibasic acid and catalyst to obtain the low-viscosity polyamide 66 resin.

9. A process for the preparation of a high viscosity polyamide 66 resin as claimed in any one of claims 1 to 8, characterized in that, The preparation method comprises solid-phase polymerizing the low-viscosity polyamide 66 resin to obtain the high-viscosity polyamide 66 resin.

10. The method of claim 9, wherein, The solid-phase polymerization is performed under a vacuum degree < 200 Pa.

11. The preparation method according to claim 9, characterized in that, The solid-phase polymerization is performed under the condition of first heating and then cooling.

12. The method of claim 11, wherein, The temperature after heating is 160-190℃.

13. The preparation method according to claim 11, characterized in that, The heating rate is 8-12℃ / min.

14. The method of claim 11, wherein, The holding time after heating is 12-24 h.

15. The method of claim 11, wherein, The temperature after cooling is room temperature.

16. The method of claim 11, wherein, The cooling rate is 8-12℃ / min.

17. A polyamide 66 resin composition characterized by, The polyamide 66 resin composition comprises the high-viscosity polyamide 66 resin according to any one of claims 1-8 and an additive.

18. Use of the high-viscosity polyamide 66 resin according to any one of claims 1-8 or the polyamide 66 resin composition according to claim 17 in a plate or a pipe.

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