CN105885036A - Polyamide resin and preparation method thereof - Google Patents

Abstract

The invention provides a polyamide resin and a preparation method thereof. The polyamide resin is characterized in that its main chain contains propylenediamine units and oxalic acid units, wherein the propylenediamine units are derived from 1,2-propylenediamine, 1,3-propylenediamine or both mixture. The present invention also provides the preparation method of the above-mentioned polyamide resin, which is characterized in that it comprises the following steps: in the presence of a solvent or without a solvent, the diamine monomer system containing propylenediamine and the oxalic acid diester mono The mixture is mixed, pre-polymerized at room temperature to 150°C to obtain a prepolymer, and the obtained prepolymer is melt-polymerized or solid-phase polymerized to obtain a polyamide resin. The polyamide resin of the invention has high temperature resistance and low water absorption, and the monomers used are widely available and cheap.

Description

A kind of polyamide resin and preparation method thereof

technical field

The invention belongs to the field of polymer materials and relates to a polyamide resin. Specifically, the present invention relates to a high-molecular-weight polyamide resin containing propylenediamine units and oxalic acid units and a preparation method thereof. The resin monomer has a wide range of sources and has excellent high temperature resistance and dimensional stability.

Background technique

Polyamide (PA) is a polymer obtained by polycondensation of amino acid or dibasic acid and diamine, commonly known as nylon. Since the successful development of PA66 by American DuPont Company in 1939, it has a history of nearly 80 years. Nylon was first used in fibers, but since the second half of the last century, due to the rapid increase in the demand for plastics to replace steel, nylon has been widely developed and used as engineering plastics due to its high strength, good toughness, and wear resistance. At the same time, PA6, PA11, PA12, PA610, PA612, MXD6, PA6T and other nylons came out one after another.

At the end of the 20th century, due to the miniaturization and high performance of electronics, electrical appliances, and information-related equipment, the requirements for material performance have further increased. The development of surface mount (SMT) technology has further promoted the miniaturization and densification of electronic components. However, with surface mount technology, each electrical component and circuit substrate must be heated in an infrared heating device at the same time, which puts forward higher requirements on the reflow resistance and dimensional stability of the manufacturing materials. At the same time, in order to reduce environmental pollution, the use of lead-free solder is now strongly advocated, and the melting point of the new tin-copper-silver solder is 30°C higher than that of the previous material. At this time, the heat resistance of commonly used materials such as PA6, PA66, and PBT cannot To meet the new requirements, therefore, it is imperative to develop a new type of nylon material with higher heat resistance.

In addition, in the automotive industry, new requirements are placed on heat-resistant materials. Improving the combustion temperature of the engine to make the fuel burn fully is an important method to reduce _CO2 emissions and reduce the fuel consumption of the car. Increasing the combustion temperature of the engine will inevitably lead to an increase in the engine room temperature, which puts forward higher requirements for the heat resistance of the materials used. In addition, the plasticization of metals in engine fuel systems, exhaust systems, and cooling systems requires alternative materials that have excellent heat resistance and are even more stringent.

Traditional high temperature resistant nylon can be divided into aromatic high heat resistant nylon and aliphatic high heat resistant nylon according to its structure.

Aromatic high temperature nylon can be divided into two categories. One is fully aromatic high temperature resistant nylon, which is synthesized from aromatic diacids and aromatic diamines. It was originally developed by DuPont in the United States in the 1960s. It has high temperature resistance, radiation resistance, corrosion resistance and wear resistance. , Self-extinguishing and other characteristics, mainly used for synthetic fiber raw materials, rubber reinforcement, etc. Due to the high melting point and high viscosity of fully aromatic nylon, it is difficult to process by melt extrusion and injection molding. The second type is semi-aromatic high-temperature-resistant nylon, which can be obtained by replacing the diamine or dibasic acid of synthetic nylon with aromatic diamine or aromatic diacid respectively. At present, the commercialized semi-aromatic nylon mainly includes polyhexamethylene terephthalamide (PA6T), polyazelane terephthalamide (PA9T), polydecanediamide terephthalamide (PA10T) and polyhexamethylene terephthalamide (PA10T). Diamide m-xylylenediamide (MXD6) and so on. Homopolymerized PA6T has excellent heat resistance and dimensional stability, but its application is limited due to its high melting point, which prevents it from being injection molded. Therefore, commercialized PA6T is a PA6T copolymer modified by copolymerization. PA9T, PA10T, and MXD6 have good heat resistance and melt processability, but because the synthesis of diamine is too cumbersome, the cost is too high, which limits their large-scale application and production.

Aliphatic high temperature resistant nylon is represented by PA46 synthesized by Dutch DSM company in 1990. PA46 is an aliphatic polyamide formed by polycondensation of butanediamine and adipic acid. Compared with PA6 and PA66, the main chain structure of PA46 is more symmetrical, which makes it have high crystallinity (the crystallinity can reach 70%) and very fast crystallization speed. Its melting temperature is as high as 295 ° C, which is much higher than PA6 and PA66 have unique properties that cannot be achieved by other products. But firstly, due to the high density of amide bonds in the structure, high saturated water absorption rate, and poor dimensional stability; secondly, the production process of its raw material butanediamine is complicated and expensive, which limit its development and application.

Contents of the invention

The object of the present invention is to provide a new type of high-temperature-resistant and low-water-absorbing nylon that is widely available and inexpensive, and its preparation method.

In order to achieve the above object, the present invention provides a polyamide resin, which is characterized in that its main chain contains propylenediamine units and oxalic acid units, wherein the propylenediamine units are derived from 1,2-propylenediamine, 1,3 - Propylenediamine or a mixture of both.

Preferably, the relative viscosity of the solution measured at 25° C. is between 1.2 and 6.0, and the solution uses 96 wt % sulfuric acid as a solvent with a concentration of 1.0 g/dl.

More preferably, the relative viscosity of the solution measured at 25° C. is between 2.0 and 4.0, and the solution uses 96 wt% sulfuric acid as a solvent with a concentration of 1.0 g/dl.

The polyamide resin in the present invention contains propylenediamine units and oxalic acid units in its main chain, and it can be a homopolymer or a copolymer. The present invention is not particularly limited for the relative viscosity of resin, but considering the intensity of resin, generally use 96wt% sulfuric acid as the solution of this resin that solvent configuration concentration is 1.0g/dl, the relative viscosity that measures at 25 ℃ is with not It is better to be less than 1.2, and more preferably not less than 2; on the other hand, considering the molding processability of the resin, the viscosity of the resin should not be too high. Generally, it is better to have a relative viscosity not greater than 6, and more preferably not greater than 4. better. To sum up, it is generally better to have a relative viscosity between 1.2-6, more preferably 2.0-4.0, and most preferably 2.5-3.5.

Preferably, the main chain of the polyamide resin also contains C2, C4-C12 diamine units.

Preferably, the molar content of propylenediamine units in all diamine units of the polyamide resin is between 1-99mol%.

The polyamide resin of the present invention may also contain C2, C4-C12 diamine units in its main chain. However, considering the source and price of diamines, ethylenediamine, butylenediamine, hexamethylenediamine, decanediamine, dodecyldiamine, m-xylylenediamine and p-xylylenediamine are preferred. Considering further that high temperature resistant polyamide resin should have good crystallinity, high heat resistance and suitable processing window, then the molar content of propylene diamine unit in all diamine units is between 1-99mol% as well, further Preferably it is 15-75 mol%, most preferably 20-40 mol%.

Preferably, its melting point Tm is between 200°C and 330°C.

Preferably, the oxalic acid units are derived from oxalic acid diesters.

More preferably, the oxalic acid diester is selected from dimethyl oxalate, diethyl oxalate, di-n-propyl oxalate, diisopropyl oxalate, di-n-butyl oxalate, diisobutyl oxalate, di-tertiary oxalate Any one or more of butyl ester and diphenyl oxalate.

The present invention also provides the preparation method of the above-mentioned polyamide resin, which is characterized in that it comprises the following steps: in the presence of a solvent or without a solvent, the diamine monomer system containing propylenediamine and the oxalic acid diester mono The body is mixed, and the prepolymerization is carried out at a temperature ranging from room temperature to 150°C to obtain a prepolymer.

Preferably, the preparation method of the polyamide resin further includes performing melt polymerization or solid state polymerization on the obtained prepolymer to obtain the polyamide resin.

Preferably, the polymerization temperature of the melt polymerization is between Tm+10° C. and Tm+50° C., and the polymerization pressure is between 100 Pa and 1 atm: where Tm is its melting point.

Preferably, the polymerization temperature of the solid state polymerization is between Tm-50°C and Tm-10°C, and the polymerization pressure is between 100Pa and 1000Pa.

In order to further increase the molecular weight of the polyamide resin, the above-mentioned prepolymerized product can be crystallized and then subjected to solid phase polymerization or melt polymerization. The temperature of solid-state polymerization should be higher than the glass transition temperature of the system, but lower than the melting point of the system. The temperature of solid-state polymerization is generally between 100°C below the melting point and 5°C below the melting point. Further optimization is between Between 50°C below the melting point and 10°C below the melting point. For the polyamide resin of the present invention, the solid state polymerization temperature is generally preferably between 200-300°C, and is further optimized to be between 250-300°C. The solid-state polymerization time is generally between 1-24h. Considering that a long time will increase the cost, and the molecular weight of polyamide resin is not easy to increase if the time is short, it is further optimized to 3-12h, and the most optimized to 6-8h. The present invention has no special limitation on the temperature of melt polymerization, generally 0-350°C is preferred. In order to control the reaction speed and avoid the volatilization of monomers, the initial temperature is generally low, generally 0-200°C is better; as the reaction progresses, the melting point of the system increases, and the polymerization temperature needs to be gradually increased, but the optimum temperature is not higher than 350°C Well, if it is too high, it will lead to thermal decomposition, which will reduce the molecular weight and easily change color, thereby deteriorating the product performance.

The present invention also provides a polyamide resin composition, which is characterized in that it contains the above-mentioned polyamide resin, and its content is 10-99wt%.

In the present invention, the temperature of the prepolymerization of the system containing propylenediamine monomer and oxalic acid monomer is not particularly limited, and is generally determined by the boiling point of monomer and solvent, polymerization rate and the like. Generally, it is carried out at room temperature - 150°C, preferably 60-100°C.

Compared with prior art, the beneficial effect of the present invention is:

The polyamide resin of the invention has high temperature resistance and low water absorption, and the monomers used are widely available and cheap.

Description of drawings

Fig. 1 is the DSC curve of the polyamide resin prepared in embodiment 1.

detailed description

Below in conjunction with specific embodiment, further illustrate the present invention. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the teachings of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

The polyamide that the present invention prepares carries out following performance test according to standard preparation sample:

Relative viscosity (ηr) test: test with reference to the national standard GB12006.1-89 of the People's Republic of China, the determination method of polyamide viscosity number. The specific test method is to measure the relative viscosity ηr of polyamide with a concentration of 1.0g/dl in 96wt% concentrated sulfuric acid at 25±0.01°C, using the NCY-2 automatic viscometer produced by Shanghai Sierda Scientific Instrument Co., Ltd. .

Melting point (Tm) test: Perkin Elmer Dimond DSC analyzer is used to test the melting point of the sample; nitrogen atmosphere, flow rate is 40mL/min; during the test, the temperature is first raised to 340°C at 10°C/min, kept at 340°C for 2min, and then heated at 10°C Cool down to 20°C per minute, set the exothermic peak temperature at this time as the crystallization temperature Tc, and then raise the temperature to 340°C at 10°C/min, set the endothermic peak temperature at this time as the melting point Tm.

Saturated water absorption at 23°C: After hot-pressing the polyamide into a film with a thickness of about 0.5mm, put the polyamide film into water at 23°C to constant weight and weigh it (W1); then place the sample in a vacuum oven at 100°C Dry to constant weight (W2), saturated water absorption rate: saturated water absorption rate = (W1-W2)/W2*100%

In all the embodiments provided by the present invention, the raw materials provided can be purchased from the market. Among them, ethylenediamine, butylenediamine, propylenediamine, hexamethylenediamine, and oxalic acid diester were all analytically pure, and were purchased from Alpha, TCl, TCl, Sigma-Aldrich, and Sigma-Aldrich, respectively.

Example 1

A polyamide resin whose main chain contains propylenediamine units and oxalic acid units, wherein the propylenediamine units are derived from 1,2-propylenediamine, the oxalic acid units are derived from dibutyl oxalate, and the propylenediamine units are present in all dibutyl oxalates The molar content in the amine unit is shown in Table 1. The preparation method is as follows: add 19.088g of 1,2-propylenediamine, 89.77g of hexamethylenediamine and 1L of toluene into a 2L four-necked flask, replace the nitrogen three times under mechanical stirring, and raise the temperature of the system to 60°C. 202.25 g of dibutyl oxalate was added dropwise through the funnel to perform prepolymerization. After the dropwise addition, filter and dry to obtain white prepolymer powder. Take 100g of prepolymer powder and put it into a solid-phase polymerization tube, place the solid-phase polymerization tube in a metal bath, and replace it with nitrogen three times, then gradually raise the temperature to 150°C, 200°C, and 230°C under vacuum and keep at each temperature 30 minutes; finally, the temperature was raised to 260° C. for solid-state polymerization for 6 hours, and the polymerization pressure was 110 Pa to obtain a light yellow product. It is determined that its relative viscosity is 3.4, its melting point is 309°C, and its saturated water absorption rate is 3.8%. Fig. 1 is the DSC curve of the polyamide resin prepared in embodiment 1.

Example 2

A polyamide resin whose main chain contains propylenediamine units and oxalic acid units, wherein the propylenediamine units are derived from 1,2-propylenediamine, the oxalic acid units are derived from dibutyl oxalate, and the propylenediamine units are present in all dibutyl oxalates The molar content in the amine unit is shown in Table 1. The preparation method is as follows: add 57.265g of 1,2-propanediamine, 29.924g of hexamethylenediamine and 1L of toluene into a 2L four-necked flask, replace the nitrogen three times under mechanical stirring, and raise the temperature of the system to 60°C. Add 202.25 g of dibutyl oxalate dropwise into the funnel. After the dropwise addition, filter and dry to obtain white prepolymer powder. Take 100 g of prepolymer powder and put it into a solid-phase polymerization tube for pre-polymerization, place the solid-phase polymerization tube in a metal bath, and replace it with nitrogen three times, then gradually raise the temperature to 150°C, 200°C, and 230°C under vacuum. The temperature was maintained for 30 minutes; finally, the temperature was raised to 260° C. for solid-state polymerization for 8 hours, and the polymerization pressure was 105 Pa to obtain a light yellow product. It is determined that its relative viscosity is 6.0, its melting point is 325°C and its water absorption rate is 4.1%.

Example 3

A polyamide resin whose main chain contains propylenediamine units and oxalic acid units, wherein the propylenediamine units are derived from 1,2-propylenediamine, the oxalic acid units are derived from dibutyl oxalate, and the propylenediamine units are present in all dibutyl oxalates The molar content in the amine unit is shown in Table 1. The preparation method is as follows: add 38.177g of 1,2-propylenediamine, 30.952g of ethylenediamine and 1L of toluene into a 2L four-necked flask, replace the nitrogen three times under mechanical stirring, and raise the temperature of the system to 110°C. 202.25 g of dibutyl oxalate was added dropwise into the funnel for prepolymerization. After the dropwise addition, filter and dry to obtain white prepolymer powder. Take 100g of prepolymer powder and put it into a solid-phase polymerization tube, place the solid-phase polymerization tube in a metal bath, replace it with nitrogen three times, and gradually raise the temperature to 150°C, 200°C, 230°C, 260°C under vacuum The temperature was maintained for 30 minutes; finally, the temperature was raised to 290° C. for solid-state polymerization for 4 hours, and the polymerization pressure was 158 Pa to obtain a light yellow product. It is determined that its relative viscosity is 2.7, its melting point is 314°C, and its saturated water absorption rate is 7.0%.

Example 4

A polyamide resin whose main chain contains propylenediamine units and oxalic acid units, wherein the propylenediamine units are derived from 1,2-propylenediamine, the oxalic acid units are derived from dimethyl oxalate, and the propylenediamine units are present in all two The molar content in the amine unit is shown in Table 1. Its preparation method is as follows: add 37.155g of 1,2-propylenediamine, 44.1g of butanediamine and 1L of toluene into a 2L four-neck flask, replace the nitrogen for 3 times under mechanical stirring, and raise the temperature of the system to 150°C. 118.09 g of dimethyl oxalate was added dropwise into the funnel to carry out prepolymerization. After the dropwise addition, filter and dry to obtain white prepolymer powder. Take 100g of prepolymer powder and put it into a solid-phase polymerization tube, place the solid-phase polymerization tube in a metal bath, replace it with nitrogen three times, and gradually raise the temperature to 150°C, 200°C, 230°C, 260°C under vacuum The temperature was maintained for 30 minutes; finally, the temperature was raised to 330° C. for 0.5 hours of melt polymerization, and the polymerization pressure was 128 Pa to obtain a light yellow product. It is determined that its relative viscosity is 3.8, its melting point is 311° C., and its saturated water absorption rate is 5.5%.

Example 5

A polyamide resin whose main chain contains propylenediamine units and oxalic acid units, wherein the propylenediamine units are derived from 1,2-propylenediamine, the oxalic acid units are derived from dimethyl oxalate, and the propylenediamine units are present in all two The molar content in the amine unit is shown in Table 1. The preparation method is as follows: add 19.088g of 1,2-propylenediamine, 89.77g of hexamethylenediamine and 1L of toluene into a 2L four-neck flask, replace the nitrogen gas for 3 times under mechanical stirring, and carry out the experiment at room temperature. 118.09 g of dimethyl oxalate was added dropwise to perform prepolymerization. After the dropwise addition, filter and dry to obtain white prepolymer powder. It is determined that its relative viscosity is 1.2, its melting point is 303°C, and its saturated water absorption rate is 4.0%.

Example 6

A polyamide resin whose main chain contains propylenediamine units and oxalic acid units, wherein the propylenediamine units are derived from 1,3-propylenediamine, the oxalic acid units are derived from diethyl oxalate, and the propylenediamine units are present in all two The molar content in the amine unit is shown in Table 1. The preparation method is as follows: add 19.088g of 1,3-propanediamine, 89.77g of hexamethylenediamine and 1L of toluene into a 2L four-necked flask, replace the nitrogen for 3 times under mechanical stirring, and raise the temperature of the system to 60°C. 146.14 g of diethyl oxalate was added dropwise through the funnel to perform prepolymerization. After the dropwise addition, filter and dry to obtain white prepolymer powder. Take 100g of prepolymer powder and put it into a solid-phase polymerization tube, place the solid-phase polymerization tube in a metal bath, and replace it with nitrogen three times, then gradually raise the temperature to 150°C, 200°C, and 230°C under vacuum and keep at each temperature 30 minutes; finally, the temperature was raised to 270° C. for solid-state polymerization for 6 hours, and the polymerization pressure was 144 Pa to obtain a light yellow product. It is determined that its relative viscosity is 3.0, its melting point is 305°C, and its saturated water absorption rate is 3.8%.

Example 7

A polyamide resin whose main chain contains propylenediamine units and oxalic acid units, wherein the propylenediamine units are derived from 1,3-propylenediamine, the oxalic acid units are derived from diphenyl oxalate, and the propylenediamine units are present in all two The molar content in the amine unit is shown in Table 1. The preparation method is as follows: add 19.088g of 1,3-propanediamine, 89.77g of hexamethylenediamine and 1L of toluene into a 2L four-necked flask, replace the nitrogen for 3 times under mechanical stirring, and raise the temperature of the system to 60°C. 242.23 g of diphenyl oxalate was added dropwise through the funnel to perform prepolymerization. After the dropwise addition, filter and dry to obtain white prepolymer powder. Take 100g of prepolymer powder and put it into a solid-phase polymerization tube, place the solid-phase polymerization tube in a metal bath, and replace it with nitrogen three times, then gradually raise the temperature to 150°C, 200°C, and 230°C under vacuum and keep at each temperature 30 minutes; finally, the temperature was raised to 260° C. for solid-state polymerization for 8 hours, and the polymerization pressure was 165 Pa to obtain a light yellow product. It is determined that its relative viscosity is 3.2, its melting point is 308°C, and its saturated water absorption rate is 5.1%.

Example 8

A polyamide resin whose main chain contains propylenediamine units and oxalic acid units, wherein the propylenediamine units are derived from 1,3-propylenediamine, the oxalic acid units are derived from dibutyl oxalate, and the propylenediamine units are present in all two The molar content in the amine unit is shown in Table 1. The preparation method is as follows: add 19.088g of 1,3-propanediamine, 124.23g of decanediamine and 1L of toluene into a 2L four-neck flask, replace the nitrogen for 3 times under mechanical stirring, and raise the temperature of the system to 60°C. 202.25 g of dibutyl oxalate was added dropwise into the funnel for prepolymerization. After the dropwise addition, filter and dry to obtain white prepolymer powder. Take 100g of prepolymer powder and put it into a solid-phase polymerization tube, place the solid-phase polymerization tube in a metal bath, and replace it with nitrogen three times, then gradually raise the temperature to 150°C, 200°C, and 230°C under vacuum and keep at each temperature 30 minutes; finally, the temperature was raised to 260° C. for solid-state polymerization for 6 hours, and the polymerization pressure was 228 Pa to obtain a light yellow product. It is determined that its relative viscosity is 2.4, its melting point is 280°C, and its saturated water absorption rate is 3.5%.

Example 9

A polyamide resin whose main chain contains propylenediamine units and oxalic acid units, wherein the propylenediamine units are derived from 1,3-propylenediamine, the oxalic acid units are derived from dibutyl oxalate, and the propylenediamine units are present in all two The molar content in the amine unit is shown in Table 1. Its preparation method is: add 19.088g of 1,3-propanediamine, 144.46g of dodecyldiamine and 1L of toluene into a 2L four-neck flask, replace nitrogen for 3 times under mechanical stirring and raise the temperature of the system to 60°C , 202.25 g of dibutyl oxalate was added dropwise through a constant pressure funnel for pre-polymerization. After the dropwise addition, filter and dry to obtain white prepolymer powder. Take 100g of prepolymer powder and put it into a solid-phase polymerization tube, place the solid-phase polymerization tube in a metal bath, and replace it with nitrogen three times, then gradually raise the temperature to 150°C, 200°C, and 230°C under vacuum and keep at each temperature 30 minutes; finally, the temperature was raised to 250° C. for solid-state polymerization for 6 hours, and the polymerization pressure was 238 Pa to obtain a light yellow product. It is determined that its relative viscosity is 2.2, its melting point is 272°C, and its saturated water absorption rate is 3.3%.

Example 10

A polyamide resin whose main chain contains propylenediamine units and oxalic acid units, wherein the propylenediamine units are derived from 1,3-propylenediamine, the oxalic acid units are derived from dibutyl oxalate, and the propylenediamine units are present in all two The molar content in the amine unit is shown in Table 1. The preparation method is as follows: add 19.088g of 1,3-propanediamine, 99.65g of m-xylylenediamine and 1L of toluene into a 2L four-neck flask, replace the nitrogen gas 3 times under mechanical stirring, and raise the temperature of the system to 60°C. 202.25 g of dibutyl oxalate was added dropwise through a constant pressure funnel to perform prepolymerization. After the dropwise addition, filter and dry to obtain white prepolymer powder. Take 100g of prepolymer powder and put it into a solid-phase polymerization tube, place the solid-phase polymerization tube in a metal bath, replace it with nitrogen three times, and gradually raise the temperature to 150°C, 200°C, 230°C, 260°C under vacuum The temperature was maintained for 30 minutes; finally, the temperature was raised to 290° C. for solid-state polymerization for 6 hours, and the polymerization pressure was 188 Pa to obtain a light yellow product. It is determined that its relative viscosity is 3.5, its melting point is 314°C, and its saturated water absorption rate is 3.1%.

Example 11

A polyamide resin whose main chain contains propylenediamine units and oxalic acid units, wherein the propylenediamine units are derived from 1,3-propylenediamine, the oxalic acid units are derived from dibutyl oxalate, and the propylenediamine units are present in all two The molar content in the amine unit is shown in Table 1. The preparation method is as follows: add 74.13g of 1,3-propylenediamine and 1L of toluene into a 2L four-necked flask, replace nitrogen three times under mechanical stirring and raise the temperature of the system to 60°C, add dioxalic acid dioxalate dropwise through a constant pressure funnel 202.25 g of butyl ester was prepolymerized. After the dropwise addition, filter and dry to obtain white prepolymer powder. Take 100g of prepolymer powder and put it into a solid-phase polymerization tube, place the solid-phase polymerization tube in a metal bath, replace it with nitrogen three times, and gradually raise the temperature to 150°C, 200°C, 230°C, 260°C, 290°C under vacuum and kept at each temperature for 30 minutes; finally, the temperature was raised to 320° C. for solid-state polymerization for 6 hours, and the polymerization pressure was 205 Pa to obtain a light yellow product. It is determined that its relative viscosity is 2.5, its melting point is 366°C, and its saturated water absorption rate is 5.9%.

Example 12

A polyamide resin whose main chain contains propylenediamine units and oxalic acid units, wherein the propylenediamine units are derived from 1,3-propylenediamine, the oxalic acid units are derived from dibutyl oxalate, and the propylenediamine units are present in all two The molar content in the amine unit is shown in Table 1. The preparation method is as follows: add 3.706g of 1,3-propanediamine, 190.19g of dodecyldiamine and 1L of toluene into a 2L four-neck flask, replace nitrogen for 3 times under mechanical stirring and raise the temperature of the system to 150°C , 118.09 g of dimethyl oxalate was added dropwise through a constant pressure funnel for prepolymerization. After the dropwise addition, filter and dry to obtain white prepolymer powder. Take 100g of prepolymer powder and put it into a solid-phase polymerization tube, place the solid-phase polymerization tube in a metal bath, and replace it with nitrogen three times, then gradually raise the temperature to 150°C, 200°C, and 230°C under vacuum and keep at each temperature 30 minutes; finally, the temperature was raised to 270° C. for melt polymerization for 1 hour, and the polymerization pressure was 174 Pa to obtain a light yellow product. It is determined that its relative viscosity is 1.9, its melting point is 232°C, and its saturated water absorption rate is 1.2%.

The performance parameters of the monomers used in Examples 1-12 and the products obtained are shown in Table 1.

Claims (10)

1. a polyamide, it is characterised in that its main chain contains propane diamine unit and oxalic acid unit, its In, propane diamine unit derives from 1,2-propane diamine, 1,3-propane diamine or both mixture.

2. polyamide as claimed in claim 1, it is characterised in that its solution records at 25 DEG C Relative viscosity is between 1.2～6.0, and described solution uses 96wt% sulphuric acid to be solvent, and concentration is 1.0g/dl.

3. polyamide as claimed in claim 1, it is characterised in that its solution records at 25 DEG C Relative viscosity is between 2.0～4.0, and described solution uses 96wt% sulphuric acid to be solvent, and concentration is 1.0g/dl.

4. polyamide as claimed in claim 1, it is characterised in that its main chain is possibly together with C2, C4-C12 Diamine unit.

5. polyamide as claimed in claim 1, it is characterised in that the third of described polyamide Diamine unit molar content in all diamine unit is between 1-99mol%.

6. polyamide as claimed in claim 1, it is characterised in that its fusing point Tm between 200～ Between 330 DEG C.

7. polyamide as claimed in claim 1, it is characterised in that described oxalic acid unit comes from grass Acid diesters.

8. polyamide as claimed in claim 7, it is characterised in that described oxalate diester is selected from Dimethyl oxalate., ethyl oxalate, DPO, oxalic acid diisopropyl ester, dibutyl oxalate, oxalic acid Any one or more in diisobutyl ester, oxalic acid di tert butyl carbonate and phenostal.

9. the preparation method of the polyamide according to any one of claim 1-8, it is characterised in that bag Containing following steps: in the presence of the solvent or solvent-free in the case of, by the diamine monomer system containing propane diamine Mix with oxalate diester monomer, at a temperature of room temperature to 150 DEG C, carry out prepolymerization, obtain prepolymer.

10. the preparation method of polyamide as claimed in claim 9, it is characterised in that described The preparation method of polyamide also includes the prepolymer of gained is carried out melt polymerization or solid phase, is gathered Amide resin.