CN115678003A

CN115678003A - High-transparency high-toughness polyamide material and preparation method thereof

Info

Publication number: CN115678003A
Application number: CN202211446560.0A
Authority: CN
Inventors: 董侠; 李璇; 王煜; 朱平; 王笃金
Original assignee: Institute of Chemistry CAS
Current assignee: Institute of Chemistry CAS
Priority date: 2022-11-18
Filing date: 2022-11-18
Publication date: 2023-02-03

Abstract

The invention provides a high-transparency high-toughness polyamide material and a preparation method thereof, which are characterized in that dibasic acid, diamine, deionized water, a catalyst and an antioxidant are mixed to obtain a raw material mixture, then the raw material mixture is added into a reaction kettle, the temperature is raised to a set temperature under a preset pressure condition for polycondensation, and the raw material mixture in the reaction kettle is vibrated and sheared in the polycondensation process to realize the adjustment of the polyamide crystal form; or the polymerization temperature is adjusted in the post polymerization process of the polyamide material to realize the adjustment of the polyamide crystal form; or the cooling rate of the cooling stage is controlled in the process of carrying out heat treatment on the polyamide material to realize the adjustment of the polyamide crystal form; the polyamide material with the gamma crystal form, which can stably exist at room temperature, is prepared by the method, and due to the stable existence of the gamma crystal form, the mechanical property of the polyamide material is improved, and the polyamide material has the characteristic of high light transmittance.

Description

High-transparency high-toughness polyamide material and preparation method thereof

Technical Field

The invention belongs to the technical field of polyamide material preparation, and particularly relates to a high-transparency high-toughness polyamide material and a preparation method thereof.

Background

Due to the existence of amide groups, strong hydrogen bonds exist among molecular chains of the common polyamide, and molecules are easy to regularly arrange, so that the common polyamide has high crystallinity, and the crystal size is large and larger than the wavelength of visible light, so that the common polyamide generally presents opaque states such as white, milky white or yellow under macroscopic view. If proper monomers are introduced into polyamide to inhibit crystallization behavior or a certain means is used to control the crystal size to be smaller than the wavelength of visible light (400-700 nm), and meanwhile, chromophoric groups do not exist in the molecular structure, under the condition of ensuring that the refractive index of a crystal region is consistent with that of an amorphous region, a macroscopically transparent polyamide material can be obtained. The key to obtaining transparent polyamides is to hinder crystallization or to reduce the crystal size. The current common modes mainly comprise the following three modes:

1. introduction of monomers with large steric hindrance

The branched, alicyclic or aromatic ring structure with large steric hindrance is introduced to the main chain of the polyamide, the regularity of the polyamide chain segment can be reduced to a great extent by hindering the movement of the molecular chain, the crystallization capability of the polyamide chain segment is obviously reduced, and the polyamide chain segment is in a microcrystalline or amorphous state, so that the polyamide chain segment is transparent.

Chinese patent application No. CN201510660451.2 discloses a semi-aromatic transparent polyamide material PA6I and a preparation method thereof, wherein isophthalic acid and hexamethylenediamine are subjected to melt polycondensation in a water solvent to obtain a PA6I material with high transparency and excellent mechanical properties.

Chinese patent application No. CN201510992965.8 discloses a method for preparing semi-aromatic transparent polyamide, which comprises performing acid-base neutralization reaction on aromatic dicarboxylic acid and alicyclic diamine in a polar aprotic solvent to obtain a mixed solution containing polyamide salt, and polymerizing to obtain high molecular weight semi-aromatic transparent polyamide.

Chinese patent with application number CN202010322055.X discloses a transparent polyamide T21 material and a preparation method thereof, and is characterized in that hexamethylenediamine, isophthalic acid and terephthalic acid are subjected to melt polycondensation or solid-phase polycondensation in a water solvent, and the characteristics of high benzene ring rigidity and transparency of semi-aromatic polyamide are combined to obtain the polyamide T21 material with better rigidity and transparency, so that the requirements of motor vehicles on oil cups and industrial glasses are completely met. However, these monomers with large steric hindrance tend to have high rigidity, so that the elongation at break and toughness are greatly reduced to cause deterioration of performance; meanwhile, the glass transition temperature and the melting point of the monomer are greatly increased after the monomer is introduced, so that the processing performance is very poor, the requirement on processing equipment is high, and the process condition is very harsh.

2. Copolymerization or blending

Different monomers are introduced to a polyamide main chain for random copolymerization modification, so that the regularity of molecular chain arrangement is damaged, the density of hydrogen bonds which can be formed is reduced, and the material has higher transparency.

Chinese patent application No. CN201210592812.0 discloses a transparent polyamide and a preparation method thereof, and a transparent polyamide material having a light transmittance of 80% or more in the visible light wavelength range is prepared by copolymerization of aliphatic diacid, alicyclic diamine and amide salt by using a copolymerization method and structural characteristics of aliphatic diacid monomer and alicyclic diamine monomer.

Chinese patent application No. CN201510861348.4 discloses a method for synthesizing high-fluidity transparent polyamide, which comprises the steps of preparing transparent polyamide by melt copolymerization of alicyclic diamine, aromatic diacid, aliphatic long-carbon-chain diacid and polyamine, and blending the transparent polyamide with long-carbon-chain semi-crystalline polyamide, wherein on the premise of ensuring light transmittance, the rigidity and toughness of the blended polyamide can be maintained, and the fluidity of the blended polyamide is improved. However, the crystal is destroyed, which results in great loss of other properties (such as mechanical properties, thermal properties, etc.).

3. Introducing fillers

By adding proper nucleating agent, the crystal is crushed and crystallized, and transparent products can be obtained. For example, by adding 0.1% of a nucleating agent, such as colloidal silica, to the PA66 or PA6 melt, it is possible to obtain crystal particles with very small grain sizes, and thus to obtain transparent products.

Chinese patent No. CN201210247411.1 discloses a method for preparing a high-transparency polyamide composite film, in which polypropylene or a polypropylene elastomer is added to a polyamide resin as a material for improving transparency, so as to prepare a high-transparency polyamide co-extruded composite film.

Chinese patent with application number CN202011489942.2 discloses a high infrared transparent nylon and a preparation method thereof, wherein a prepolymer prepared from long carbon chain diamine and aliphatic long carbon chain dibasic acid according to a molar ratio of 1. However, since the polyamide crystallizes at a very high rate, the crystallization is difficult to control and the transparency of the products obtained using this process is limited.

In summary, the current methods for polyamides with high transparency are mainly focused on the above three methods. However, these three methods have some disadvantages: for example, the method of introducing the large steric hindrance monomers improves the transparency, and the large steric hindrance monomers often have high rigidity, so that the elongation at break and the toughness of the large steric hindrance monomers are greatly reduced, and the performance is deteriorated; meanwhile, the glass transition temperature and the melting point of the monomer are greatly increased after the monomer is introduced, so that the processing performance is very poor, the requirement on processing equipment is high, and the process conditions are harsh. In addition, the key factor determining the performance of polymer composites is compatibility, methods of adding small molecule fillers or second polymers often suffer from poor interaction between the filler or second polymer and the matrix polymer, leading to agglomeration or phase separation in the matrix, while adding a third component as a compatibilizer increases the cost and complexity of the system.

In view of the above, the present invention is particularly proposed.

Disclosure of Invention

The technical problem to be solved by the invention is to overcome the defects of the prior art and provide a high-transparency high-toughness polyamide material and a preparation method thereof, wherein the raw material mixture is subjected to oscillation shearing treatment in the preparation process of the polyamide material, and the temperature in the preparation process of the polyamide material is controlled; or adjusting the post-polymerization temperature in the post-polymerization process of the polyamide material; or controlling the cooling speed in the process of carrying out heat treatment on the polyamide material to prepare the polyamide material with stable gamma crystal form. On the other hand, the invention provides a high-transparency high-toughness polyamide material, because the polyamide material has a gamma crystal form, and the content of a straightened chain structure contained in the gamma crystal is less than that of the alpha crystal, the Young modulus of the gamma crystal is lower but the toughness is higher, the mechanical property of the polyamide is greatly improved, and meanwhile, the polyamide with the gamma crystal form prepared by the preparation method has the characteristic of high light transmittance.

In order to achieve the above object, a first aspect of the present invention provides a method for preparing a high-transparency high-toughness polyamide material, comprising the steps of:

s1, mixing dibasic acid, diamine, deionized water, a catalyst and an antioxidant to obtain a raw material mixture;

s2, heating to a first preset temperature under a preset pressure condition to perform polycondensation reaction on the raw material mixture, and performing oscillation shearing treatment on the raw material mixture in the heating process;

s3, cooling and discharging after the polycondensation reaction is finished to obtain a polyamide material with a gamma crystal form;

the dibasic acid and the diamine in the raw material mixture are the dibasic acid and the diamine with even number of C on the main chain;

preferably, the antioxidant is one or more of a mixture of phenolic antioxidant, ester antioxidant, metal ion deactivator, or peroxide decomposer;

more preferably, the phenolic antioxidants are antioxidant 1010, antioxidant 1098, antioxidant 1035 and antioxidant 1093; the amine antioxidant is antioxidant DNP and antioxidant 4010; the metal ion passivator is copper acetate/potassium iodide; the peroxide decomposer is an antioxidant 168;

preferably, the catalyst is sodium hypophosphite.

Specifically, step S3 is to continue heating for a period of time after pressure relief and drainage, then cooling and discharging to obtain the polyamide material with the gamma crystal form

The scheme limits the temperature and pressure of the polycondensation reaction and the types of the dibasic acid and the diamine in the raw material mixture, adds a vibration shearing process in the polycondensation reaction process, realizes the control of the crystal structure of the polyamide material through the cooperation of the vibration shearing process and the reaction regulation, and further can obtain the polyamide material with the stable gamma crystal form.

Further, in step S2, the temperature of the polycondensation reaction is increased from room temperature to a first preset temperature, the first preset temperature is between 80 ℃ below the melting temperature of the polyamide material with the gamma crystal form and the initial thermal decomposition temperature, and after the temperature reaches the melting temperature of the polyamide material with the gamma crystal form, the raw material mixture is subjected to oscillation shearing treatment.

In the scheme, the vibration shearing treatment is limited to be started after the polycondensation reaction temperature reaches the melting temperature of the polyamide material with the gamma crystal form, and at the moment, part of solid in the raw material mixture is melted into liquid, so that the raw material mixture can be better treated through the vibration shearing; if the temperature is lower than the melting temperature of the polyamide material with the gamma crystal form, the vibration shearing is started, part of the raw materials are still in a solid state and cannot be influenced by the vibration shearing.

Preferably, the first predetermined temperature is between 20 ℃ below and 30 ℃ above the melting temperature of the polyamide material having the gamma crystalline form.

In the above preferred embodiment, if the first preset temperature is higher than the initial thermal decomposition temperature, the raw material mixture is decomposed while being polymerized, resulting in a decrease in the yield of the reaction and, at the same time, a byproduct may be generated to affect the purity of the product.

Further, in step S2, the reaction temperature is increased to a first preset temperature by a step-wise temperature increase method, wherein the temperature of at least one temperature increase stage is higher than the melting temperature of the polyamide material with the gamma crystal form.

According to the scheme, the accuracy of temperature control is improved in a segmented temperature rise mode, wherein the temperature of at least one temperature rise stage is higher than the melting temperature of the polyamide material with the gamma crystal form, so that the raw material mixture can be subjected to oscillation shearing, the oscillation shearing and the polycondensation reaction are matched in temperature, and the control accuracy is improved.

Further, the duration of each temperature rise stage is 1-5h; preferably, the duration is in the range of 2 to 3 hours.

Further, the segmented temperature rise process at least comprises two temperature rise stages which are higher than the melting temperature of the polyamide material with the gamma crystal form, wherein at least one temperature rise stage carries out oscillation shearing treatment.

In the scheme, the temperature rise process comprises at least two temperature rise stages higher than the melting temperature of the polyamide material with the gamma crystal form, and at least one temperature rise stage is subjected to oscillation shearing treatment, so that the oscillation shearing duration can be controlled according to actual requirements, and the gamma crystal form ratio can be adjusted.

Preferably, the last temperature rise stage is subjected to oscillating shearing treatment.

The preferable scheme is obtained by technicians on the basis of a large amount of calculation and experiments, the last temperature rise stage is controlled to carry out oscillation shearing treatment, the reaction system can be ensured to be in a sheared state before the polycondensation reaction is finished, and the performance of the prepared polyamide material is improved.

Further, the temperature raising stage comprises a first temperature raising stage, a second temperature raising stage and a third temperature raising stage, wherein the temperature is raised in sequence, the second temperature raising stage and the third temperature raising stage are both subjected to oscillation shearing treatment, and the oscillation shearing treatment duration of the third temperature raising stage is shorter than that of the second temperature raising stage.

Further, the duration of the vibration shearing treatment is not more than 2h; the amplitude range of the oscillating shearing treatment is 3-30%.

Preferably, the duration of the oscillating and shearing treatment is 0.5-1h; the amplitude range of the oscillating shearing treatment is 3-10%.

Since the product is degraded due to too long oscillation shearing time, a great deal of calculation and research show that the degradation of the product can be avoided while ensuring the stable generation of the gamma crystal form by controlling the oscillation shearing time not to exceed two hours; preferably, the oscillating shear is started after the temperature is stabilized in the temperature rise stage in which the oscillating shear is required.

Meanwhile, the amplitude of the oscillating and shearing treatment is an optimal range obtained by technicians on the basis of a large number of researches and experiments, and if the amplitude is smaller than the optimal range, the amplitude of oscillating and shearing is smaller, so that the polyamide material with the gamma crystal form cannot be smoothly prepared; if the amplitude is too large, degradation of the product may be promoted, resulting in failure to obtain a polyamide material having a stable gamma crystal form.

Further, in step S2, before the temperature is raised, the air is replaced with inert gas, a part of the inert gas is reserved to reach a preset pressure, and then the temperature is raised to perform a polycondensation reaction, wherein the preset pressure is in a range of 0.05 to 1.0MPa.

Further, in step S3, the heating is continued for a period of time after pressure relief and water drainage, the heating temperature is between the melting temperature and 30 ℃ above the melting temperature, and the heating time is not more than 2h.

Preferably, the heating temperature is between the melting temperature and 10 ℃ above the melting temperature, and the heating time is not more than 1h.

In the scheme, the pressure relief process is to remove a large amount of water molecule products generated in the polymerization process, so that the reaction is carried out in the forward direction to obtain the polyamide material with high molecular weight. Meanwhile, the heating temperature in the pressure relief drainage stage is between the melting temperature and 10 ℃ above the melting temperature, the heating time is not more than 1h, and the molecular weight of the material is improved while the influence caused by the oscillating shearing treatment in the previous temperature rise stage is not eliminated.

The invention also provides a preparation method of the high-transparency high-toughness polyamide material, which comprises the steps of carrying out post-polymerization reaction on the polyamide material in solid-phase tackifying equipment, adjusting the molecular weight and the distribution of the polyamide material by adjusting the temperature of the post-polymerization reaction, further realizing the regulation and control of crystal form, and preparing the polyamide material with gamma crystal form, wherein the temperature in the post-polymerization reaction process is between the glass transition temperature and the melting temperature of the polyamide material.

Preferably, the length of the postpolymerization is from 1 to 14h.

More preferably, the length of the postpolymerization is from 2 to 8 hours.

Further, the polyamide material with the gamma crystal form prepared by the former preparation method is put into solid-phase tackifying equipment for post-polymerization reaction.

According to the scheme, the polyamide material with the gamma crystal form is further subjected to post-polymerization reaction, the gamma crystal form in the amide can be perfected, and the mechanical property and the light transmittance of the polyamide material with the gamma crystal form are further improved.

The invention also provides a preparation method of the high-transparency high-toughness polyamide material, which comprises the steps of completely dehydrating the polyamide material, heating the polyamide material to a temperature higher than the melting point in an inert atmosphere to eliminate the heat history, and continuously replacing air before and during heating to keep the inert atmosphere; then cooling to 40 ℃ below the melting point of the polyamide material at a speed of not less than 5 ℃/min to obtain the polyamide material with a gamma crystal form;

or after the polyamide material is completely dehydrated, heating to a second preset temperature in an inert atmosphere, then carrying out heat treatment on the polyamide material by heat preservation, and then cooling to 40 ℃ below the melting point of the polyamide material at a speed of not less than 5 ℃/min to obtain the polyamide material with the gamma crystal form;

the inert atmosphere is high-purity helium, high-purity nitrogen or high-purity argon, and the vacuum degree under the inert atmosphere is maintained at-0.1-1 MPa.

Preferably, the inert atmosphere is high-purity helium or high-purity nitrogen;

preferably, the temperature is reduced to room temperature at a speed of not less than 5 ℃/min to obtain the polyamide material with the gamma crystal form.

In this case, the water content of the polyamide material is assumed to be 0%, and the polyamide material is completely dehydrated, which means that the weight of the polyamide material does not change when measured by a constant weight method.

In the scheme, after the thermal history is completely eliminated, the hydrogen bonds in the melt are disordered, and the hydrogen bonds can be recombined and arranged into ordered hydrogen bonds in the subsequent cooling process. The order degree of subsequent hydrogen bonds can be controlled by changing the cooling rate, so that the gamma crystal with the disordered arrangement of the hydrogen bonds is obtained.

Further, the second preset temperature is between the melting temperature of the polyamide material and 30 ℃ above the melting temperature, and the heat treatment time is 5-30min.

Further, the polyamide material with the gamma crystal form prepared by the method is one of PA66, PA610 and PA612, or the polyamide with the number of methylene groups between adjacent amide groups on the main chain not less than 10.

More preferably, the polyamide material produced is one of PA1010, PA1012, PA1210, PA1212 or PA 1214.

The second aspect of the invention provides a high-transparency high-toughness polyamide material prepared by the method.

Specifically, the elongation at break of the prepared polyamide material with the gamma crystal form is 101-210% of that of the conventional polyamide material, the toughness is 101-200% of that of the conventional polyamide material, and the light transmittance is 80-100%.

After adopting the technical scheme, compared with the prior art, the invention has the following beneficial effects:

1. according to the preparation method of the high-transparency high-toughness polyamide, the raw material mixture is subjected to vibration shearing treatment in the polycondensation reaction process; or adjusting the post-polymerization temperature in the process of post-polymerizing the polyamide material; or the cooling speed is controlled in the process of carrying out heat treatment on the polyamide material to prepare the polyamide with the gamma crystal form, the fracture elongation and toughness of the polyamide can be obviously improved due to the formation of the gamma crystal form, and meanwhile, the original opaque polyamide is changed into the high transparent polyamide due to the gamma crystal form.

2. The preparation method of the high-transparency high-toughness polyamide provided by the invention is a physical method, is simple and direct to operate, and can improve the toughness and the transparency without other additives and chemical methods; and the whole process is environment-friendly without pollution, and is suitable for popularization and use.

The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.

Drawings

FIG. 1 is a comparison of one-dimensional WAXD curves for a high transparency, high toughness polyamide material prepared according to the method of the present invention in example fifteen;

FIG. 2 is the result of peak separation treatment of the one-dimensional WAXD curve corresponding to the alpha crystal form and the gamma crystal form;

FIG. 3 is a comparison of stress-strain comparison curves for a high transparent, high toughness polyamide material made in accordance with the method of making example fifteen of the present invention;

FIG. 4 is a graph showing the comparison of the transparency of the high-transparency high-toughness polyamide material prepared by the method of the fifteenth embodiment of the invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and the following embodiments are used for illustrating the present invention and are not intended to limit the scope of the present invention.

In the present invention, the melting start temperature and the melting point temperature are measured by using a differential scanning calorimeter in a nitrogen atmosphere at a rate of 10 ℃/min from room temperature to 250 ℃, and the start thermal decomposition temperature is measured by using a thermogravimetric analyzer in a nitrogen atmosphere at a rate of 10 ℃/min from 50 ℃ to 700 ℃.

The crystalline forms were tested by using an X-ray diffractometer (Xeuss 2.0) from Xenocs, france, using a Cu Ka light source (GeniX 3D Cu ULD) as copper target with a wavelength of

To obtain results with good signal-to-noise ratio, an exposure time of 300s was used. The distance from the sample to the detector was 134mm. Corresponding two-dimensional WAXD patterns were collected with a semiconductor detector (Pilatus 300k, dectris) with a two-dimensional image resolution of 487 × 619pixels, each pixel having a size of 172 × 172 μm2. And (4) carrying out detector noise, air scattering and sample absorption correction on the obtained two-dimensional WAXD pattern, and then integrating to obtain a one-dimensional WAXD curve.

Mechanical testing tensile properties were tested by using a tensile machine (Instron 3365) at 25 deg.C, relative humidity 30% RH, tensile rate 20mm/min, which was repeated at least 10 times per sample.

The light transmittance was measured by a light transmittance/haze meter.

The oscillating shear is to apply periodic rotary shear to the sample to realize oscillation of the sample, and the amplitude of the oscillating shear is controlled to be 3-30% by controlling the frequency of the rotary shear.

The present invention will be described in further detail with reference to specific examples.

Example one

As an embodiment of the present invention, this embodiment provides a method for preparing a high-transparency high-toughness polyamide material, where the prepared polyamide material is PA66, the melting temperature of PA66 is 257 ℃, and the initial thermal decomposition temperature is 437 ℃, and specifically includes the following steps:

s1, mixing adipic acid, hexamethylenediamine, an antioxidant 1098, sodium hypophosphite and deionized water in a mass ratio of 1.2;

s2, replacing air in the high-pressure reaction kettle with inert gas, repeating the steps for three times, reserving 1MPa of inert gas, heating to 280 ℃ in a three-section heating mode to perform polycondensation reaction, wherein the first heating stage is heated to 200 ℃ from room temperature; the second temperature rise stage is to raise the temperature from 200 ℃ to 240 ℃; in the third temperature rise stage, the temperature is raised from 240 ℃ to 280 ℃, and the temperature is kept constant for 2 hours after each temperature rise stage is raised to the target temperature; simultaneously, in a third temperature rising stage, oscillating shearing is applied to the raw material mixture, and the amplitude of the oscillating shearing is 10%;

and S3, continuously heating for 1h at 260 ℃ after pressure relief of the reaction kettle, and then cooling and discharging to obtain the PA66 material with the gamma crystal form.

It should be noted that, because water is generated during the reaction process, the pressure in the reaction kettle is increased due to the continuous volatilization of water in a high-temperature environment.

Example two

As another embodiment of the present invention, this embodiment provides a method for preparing a high-transparency high-toughness polyamide material, where the prepared polyamide material is PA1214, the melting temperature of PA1214 is 184 ℃, and the thermal decomposition temperature is 400 ℃, and specifically includes the following steps:

s1, mixing tetradecanedioic acid, dodecamethylenediamine, an antioxidant 1010, sodium hypophosphite and deionized water in a mass ratio of 1.1;

s2, replacing air in the high-pressure reaction kettle with inert gas, repeating the steps for three times, reserving 0.05MPa of inert gas, heating to 200 ℃ in a three-section heating mode to perform polycondensation reaction, wherein the first heating stage is heated to 160 ℃ from room temperature; in the second temperature rise stage, the temperature is raised from 160 ℃ to 180 ℃; in the third temperature rise stage, the temperature is raised from 180 ℃ to 200 ℃, and the temperature is kept constant for 3 hours after the temperature is raised to the target temperature in each temperature rise stage; simultaneously, in a third temperature rising stage, vibration shearing is applied to the raw material mixture, and the amplitude of the vibration shearing is 5%;

and S3, after the pressure of the reaction kettle is relieved, the temperature is maintained at 184 ℃, the heating is continued for 2 hours, and then the cooling and discharging are carried out to obtain the PA1214 material with the gamma crystal form.

EXAMPLE III

As another embodiment of the present invention, this example provides a method for preparing a high-transparency high-toughness polyamide material, where the prepared polyamide material is PA1012, the melting temperature of PA1012 is 189 ℃, and the thermal decomposition temperature is 406 ℃, and specifically includes the following steps:

s1, mixing dodecanedioic acid, decamethylene diamine, an antioxidant 168, sodium hypophosphite and deionized water in a mass ratio of 1.3;

s2, replacing air in the high-pressure reaction kettle with inert gas, repeating the steps for three times, reserving 0.8MPa of inert gas, heating to 230 ℃ in a three-section heating mode to perform polycondensation reaction, wherein the temperature is raised from room temperature to 190 ℃ in a first heating stage; the temperature is raised from 190 ℃ to 210 ℃ in the second temperature raising stage; in the third temperature rise stage, the temperature is raised from 210 ℃ to 230 ℃, and the temperature is kept constant for 1h after each temperature rise stage is raised to the target temperature; simultaneously, in a third temperature rising stage, oscillating shearing is applied to the raw material mixture, and the amplitude of the oscillating shearing is 15%;

and S3, after the pressure of the reaction kettle is relieved, the temperature is maintained at 190 ℃, the heating is continued for 2 hours, and then the cooling and discharging are carried out, so that the PA1012 material with the gamma crystal form is obtained.

Example four

s1, mixing dodecanedioic acid, decamethylene diamine, an antioxidant 4010, sodium hypophosphite and deionized water in a mass ratio of 1.2;

s2, replacing air in the high-pressure reaction kettle with inert gas, repeating the steps for three times, reserving 0.1MPa of inert gas, heating to 220 ℃ in a three-section heating mode to perform polycondensation reaction, wherein the first heating stage is heated to 180 ℃ from room temperature; in the second temperature rise stage, the temperature is raised from 180 ℃ to 200 ℃; the temperature of the third temperature rise stage is raised from 200 ℃ to 220 ℃, and the temperature of each temperature rise stage is raised to the target temperature and then isothermal for 2 hours; simultaneously, in a third temperature rising stage, oscillating shearing is applied to the raw material mixture, and the amplitude of the oscillating shearing is 8%;

and S3, after the pressure of the reaction kettle is relieved, the temperature is maintained at 200 ℃, the heating is continued for 2 hours, and then the cooling and discharging are carried out, so that the PA1012 material with the gamma crystal form is obtained.

EXAMPLE five

As another embodiment of the present invention, this embodiment provides a method for preparing a high-transparency high-toughness polyamide material, where the prepared polyamide material is PA610, the melting temperature of PA610 is 222 ℃, and the thermal decomposition temperature is 420 ℃, and specifically includes the following steps:

s1, mixing sebacic acid, hexamethylenediamine, an antioxidant DNP, sodium hypophosphite and deionized water in a mass ratio of 1.1;

s2, replacing air in the high-pressure reaction kettle with inert gas, repeating the steps for three times, reserving 1MPa of inert gas, heating to 240 ℃ in a three-section heating mode to perform polycondensation reaction, wherein the first heating stage is heated to 200 ℃ from room temperature; the second temperature rise stage is to raise the temperature from 200 ℃ to 220 ℃; the temperature of the third temperature rise stage is raised from 220 ℃ to 240 ℃, and the temperature is kept constant for 3 hours after the temperature of each temperature rise stage is raised to the target temperature; simultaneously, in a third temperature rising stage, oscillating shearing is applied to the raw material mixture, and the amplitude of the oscillating shearing is 10%;

and S3, after pressure relief is carried out on the reaction kettle, the temperature is maintained at 230 ℃, heating is continuously carried out for 1h, and then cooling and discharging are carried out, so that the PA610 material with the gamma crystal form is obtained.

EXAMPLE six

s1, mixing sebacic acid, hexamethylenediamine, an antioxidant 1035, sodium hypophosphite and deionized water in a mass ratio of 1.3;

s2, replacing air in the high-pressure reaction kettle with inert gas, repeating the steps for three times, reserving 0.8MPa of inert gas, heating to 240 ℃ in a three-section heating mode to perform polycondensation reaction, wherein the first heating stage is heated to 200 ℃ from room temperature; the second temperature rise stage is to raise the temperature from 200 ℃ to 220 ℃; in the third temperature rise stage, the temperature is raised from 220 ℃ to 240 ℃, and the temperature is kept constant for 2 hours after the temperature is raised to the target temperature in each temperature rise stage; simultaneously, in a third temperature rising stage, oscillating shearing is applied to the raw material mixture, and the amplitude of the oscillating shearing is 20%;

and S3, continuously heating for 2h after the pressure of the reaction kettle is relieved and the temperature of the reaction kettle is maintained at 230 ℃, and then cooling and discharging to obtain the PA610 material with the gamma crystal form.

EXAMPLE seven

In another embodiment of the present invention, a method for preparing a high-transparency high-toughness polyamide material is provided.

Putting a polyamide material PA1212 into a vacuum oven, drying at 75 ℃ for 20h, determining that the weight of the PA1212 is not changed any more through a constant weight method test, taking out the PA1212, putting into solid-phase tackifying equipment, performing post polymerization at 185 ℃, maintaining the solid-phase tackifying equipment in a high-purity nitrogen atmosphere in the post polymerization process, wherein the post polymerization time is 8h, and cooling to room temperature after the post polymerization is finished to obtain the polyamide material with the gamma crystal form.

Example eight

Putting a polyamide material PA610 into a vacuum oven, drying for 11h at the temperature of 105 ℃, determining that the weight of the PA610 does not change any more through a constant weight method test, taking out the PA610, putting into solid-phase tackifying equipment, performing post polymerization at the temperature of 225 ℃, maintaining the solid-phase tackifying equipment in a vacuum state in the post polymerization process, wherein the post polymerization time is 6h, and cooling to room temperature after the post polymerization is finished to obtain the polyamide material with the gamma crystal form.

Example nine

Putting a polyamide material PA612 into a vacuum oven, drying for 18h at the temperature of 100 ℃, determining that the weight of the PA612 is not changed any more through a constant weight method test, taking out the PA612, putting the PA612 into solid-phase tackifying equipment, performing post polymerization at the temperature of 215 ℃, maintaining the solid-phase tackifying equipment in a vacuum state in the post polymerization process, wherein the post polymerization time is 7h, and cooling to room temperature after the post polymerization is finished to obtain the polyamide material with the gamma crystal form.

Example ten

Putting a compound of a polyamide material PA1212 and a nucleating agent into a vacuum oven, wherein the dosage of the nucleating agent is 0.5wt% of that of the PA1212, drying at 105 ℃ for 10h, determining that the weight of the compound is not changed through a constant weight method test, taking out the compound, putting the compound into solid-phase tackifying equipment, performing post polymerization at 160 ℃, maintaining the solid-phase tackifying equipment in a vacuum state in the post polymerization process, wherein the post polymerization time is 5h, and cooling to room temperature after the post polymerization is finished to obtain the polyamide material with the gamma crystal form.

EXAMPLE eleven

Putting a polyamide material PA1212/PP alloy into a vacuum oven, drying for 24h at the temperature of 100 ℃, determining that the weight of the PA1212/PP alloy does not change any more through a constant weight method test, taking out the PA1212/PP alloy, putting the PA1212/PP alloy into solid-phase tackifying equipment, performing post polymerization at the temperature of 189 ℃, maintaining the solid-phase tackifying equipment in a vacuum state in the post polymerization process, wherein the post polymerization time is 6h, and cooling to room temperature after the post polymerization is finished to obtain the polyamide material with the gamma crystal form.

Example twelve

Putting a polyamide material PA 1010/glass fiber composite material into a vacuum oven, drying for 24h at the temperature of 100 ℃, determining that the weight of the PA 1010/glass fiber composite material is not changed through a constant weight method test, taking out the PA 1010/glass fiber composite material, putting the PA 1010/glass fiber composite material into solid-phase tackifying equipment, performing post polymerization at the temperature of 200 ℃, maintaining the solid-phase tackifying equipment in a vacuum state in the post polymerization process, wherein the post polymerization time is 3h, and cooling to room temperature after the post polymerization is finished to obtain the polyamide material with the gamma crystal form.

EXAMPLE thirteen

Putting a polyamide material PA1214 into a vacuum oven, drying for 18h at 100 ℃, determining that the weight of the PA1214 does not change through a constant weight method test, taking out the PA1214, putting into solid-phase tackifying equipment, performing post polymerization at 165 ℃, maintaining the solid-phase tackifying equipment in a vacuum state in the post polymerization process, wherein the post polymerization time is 3h, and cooling to room temperature after the post polymerization is finished to obtain the polyamide material with the gamma crystal form.

Example fourteen

Putting a polyamide material PA612 into a vacuum oven, drying for 20h at the temperature of 95 ℃, determining that the weight of the PA612 is not changed any more through a constant weight method test, taking out the PA612, putting the PA612 into solid-phase tackifying equipment, performing post polymerization at the temperature of 200 ℃, maintaining the solid-phase tackifying equipment in a vacuum state in the post polymerization process, wherein the post polymerization time is 10h, and cooling to room temperature after the post polymerization is finished to obtain the polyamide material with the gamma crystal form.

Example fifteen

Firstly, putting a polyamide material PA1012 into a vacuum oven, drying for 24 hours at the temperature of 95 ℃, and determining that the weight of the PA1012 is not changed any more through a constant weight method test; then heating the PA1012 to 230 ℃ to eliminate thermal history, continuously replacing air before heating and in the heating process to keep inert atmosphere, cooling to 120 ℃ at a cooling rate of 60 ℃/min after the temperature reaches 230 ℃, and naturally cooling to room temperature to obtain the polyamide material with the gamma crystal form.

The polyamide material with the gamma crystal form prepared in the fifteenth embodiment is characterized by a crystal structure by using WAXD, the characterization results are shown in fig. 1 and fig. 2, wherein a in fig. 2 is a WAXD characterization result of the polyamide material with the gamma crystal form prepared in the present embodiment, b is a WAXD characterization result of the polyamide material which is prepared by using the same polyamide material as the present embodiment and is subjected to conventional heat treatment, and it can be seen from the drawings that the crystal form of the polyamide material prepared by using the method in the fifteenth embodiment is transformed from alpha crystal to gamma crystal; the interplanar spacing crystal forms of different crystal planes corresponding to the alpha and gamma crystal forms in fig. 2 are processed to obtain the following average crystal grain sizes of the crystal forms:

the average grain size of the gamma crystal is far lower than that of the alpha crystal, so that the light transmittance of the polyamide material with the gamma crystal is higher, and the whole material is transparent.

Further, the mechanical properties of the polyamide material before and after the treatment by the fifteen methods of the example were tested, and the results are as follows:

in the above table, the post-treatment means the polyamide material prepared according to the embodiment, and the pre-treatment means the sample that is cooled to room temperature at a slow rate (2 ℃/min) after the thermal history is removed under the same conditions.

As can be seen from the table and fig. 3, the polyamide material treated by the method described in example fifteen has a reduced elastic modulus and yield strength and an improved elongation at break and toughness compared to the polyamide material before treatment, which indicates that the generation of the gamma crystal form significantly improves the deformability and toughness of the material.

Example sixteen

Firstly, putting a polyamide material PA1012 into a vacuum oven, drying for 24 hours at 85 ℃, and determining that the weight of the PA1012 is not changed any more through a constant weight method test; then heating the PA1012 to 240 ℃ to eliminate thermal history, continuously replacing air before heating and in the heating process to keep inert atmosphere, cooling to 100 ℃ at a cooling rate of 60 ℃/min after the temperature reaches 240 ℃, and naturally cooling to room temperature to obtain the polyamide material with the gamma crystal form.

Example seventeen

Firstly, putting a polyamide material PA610 into a vacuum oven, drying for 8 hours at the temperature of 105 ℃, and determining that the weight of the PA610 is not changed any more through a constant weight method test; and then heating the PA610 to 250 ℃ to eliminate thermal history, continuously replacing air before heating and in the heating process to keep inert atmosphere, and cooling to room temperature in a quenching mode after the temperature reaches 250 ℃ to obtain the polyamide material with the gamma crystal form.

EXAMPLE eighteen

Firstly, putting a polyamide material PA612 into a vacuum oven, drying for 12 hours at the temperature of 100 ℃, and determining that the weight of the PA612 is not changed any more through a constant weight method test; and then heating the PA612 to 250 ℃ to eliminate thermal history, continuously replacing air before heating and in the heating process to keep inert atmosphere, cooling to 130 ℃ at the cooling rate of 80 ℃/min after the temperature reaches 250 ℃, and naturally cooling to room temperature to obtain the polyamide material with the gamma crystal form.

Example nineteenth

Firstly, placing a polyamide material PA612 and chain extender composite in a vacuum oven, drying for 12 hours at the temperature of 100 ℃, and determining that the weight of the PA612 and chain extender composite is not changed through a constant weight method test, wherein the chain extender accounts for 0.5wt% of the PA 612; and then heating the compound of the PA612 and the chain extender to 250 ℃ to eliminate thermal history, continuously replacing air before and during the heating process to keep inert atmosphere, cooling to 80 ℃ at the cooling rate of 100 ℃/min after the temperature reaches 250 ℃, and naturally cooling to room temperature to obtain the polyamide material with the gamma crystal form.

Example twenty

Firstly, putting a polyamide material PA1210 into a vacuum oven, drying for 24 hours at the temperature of 90 ℃, and determining that the weight of the PA1210 is not changed through a constant weight method test; and then heating the PA1210 to 230 ℃ to eliminate thermal history, continuously replacing air before heating and in the heating process to keep inert atmosphere, cooling to 100 ℃ at the cooling rate of 100 ℃/min after the temperature reaches 230 ℃, and naturally cooling to room temperature to obtain the polyamide material with the gamma crystal form.

Example twenty one

Firstly, putting a polyamide material PA1212 into a vacuum oven, drying for 24 hours at the temperature of 90 ℃, and determining that the weight of the PA1212 is not changed any more through a constant weight method test; and then heating the PA1212 to 220 ℃ to eliminate thermal history, continuously replacing air before and during the heating process to keep inert atmosphere, cooling to 50 ℃ at a cooling rate of 100 ℃/min after the temperature reaches 220 ℃, and naturally cooling to room temperature to obtain the polyamide material with the gamma crystal form.

Example twenty two

Firstly, putting a polyamide material PA1214 into a vacuum oven, drying for 18 hours at the temperature of 100 ℃, and determining that the weight of the PA1214 is not changed any more through a constant weight method test; and then heating the PA1214 to 220 ℃ to eliminate thermal history, continuously replacing air before heating and in the heating process to keep inert atmosphere, cooling to 130 ℃ at a cooling rate of 60 ℃/min after the temperature reaches 220 ℃, and naturally cooling to room temperature to obtain the polyamide material with the gamma crystal form.

Example twenty three

Firstly, putting a polyamide material PA66 into a vacuum oven, drying for 24 hours at the temperature of 100 ℃, and determining that the weight of the PA66 is not changed any more through a constant weight method test; and then heating the PA66 to 290 ℃ to eliminate thermal history, continuously replacing air before and during the heating process to keep inert atmosphere, cooling to 150 ℃ at the cooling rate of 100 ℃/min after the temperature reaches 290 ℃, and naturally cooling to room temperature to obtain the polyamide material with the gamma crystal form.

Example twenty four

This comparative example employed the same preparation method as example seven, differing from example seven only in that the polyamide material having a gamma-crystalline form prepared in example one was subjected to post-polymerization.

S1, mixing adipic acid, hexamethylenediamine, an antioxidant 1098, sodium hypophosphite and deionized water (mass ratio is 1.2;

s2, replacing air in the high-pressure reaction kettle with inert gas, repeating the steps for three times, reserving 1MPa of inert gas, heating to 280 ℃ in a three-section heating mode to perform polycondensation reaction, wherein the first heating stage is heated to 200 ℃ from room temperature; the second temperature rise stage is to raise the temperature from 200 ℃ to 240 ℃; in the third temperature rise stage, the temperature is raised from 240 ℃ to 280 ℃, and the temperature is kept constant for 2 hours after each temperature rise stage is raised to the target temperature; simultaneously, in a third temperature rise stage, applying oscillation shearing to the raw material mixture, wherein the amplitude of the oscillation shearing is 10%;

s3, after pressure relief, maintaining the temperature of 260 ℃ for continuous heating for 1h, and then cooling and discharging to obtain a primary material PA 66.

Putting a polyamide material PA66 into a vacuum oven, drying for 20h at the temperature of 75 ℃, determining that the weight of the PA66 does not change through a constant weight method test, taking out the PA66, putting the PA66 into solid-phase tackifying equipment, performing post polymerization at the temperature of 200 ℃, maintaining the solid-phase tackifying equipment in a high-purity nitrogen atmosphere in the post polymerization process, wherein the post polymerization time is 8h, and cooling to room temperature after the post polymerization is finished to obtain the polyamide material with the gamma crystal form.

Example twenty-five

This comparative example employed the same preparation method as in example eight, differing from example eight only in that the polyamide material having a γ -crystalline form prepared in example four was subjected to post-polymerization.

S1, mixing dodecanedioic acid, decamethylene diamine, an antioxidant 4010, sodium hypophosphite and deionized water (mass ratio of 1.2;

s2, replacing air in the high-pressure reaction kettle with inert gas, repeating the steps for three times, reserving 0.1MPa of inert gas, heating to 220 ℃ in a three-section heating mode to perform polycondensation reaction, wherein the first heating stage is heated to 180 ℃ from room temperature; the second temperature rise stage is to raise the temperature from 180 ℃ to 200 ℃; the temperature of the third temperature rise stage is raised from 200 ℃ to 220 ℃, and the temperature of each temperature rise stage is raised to the target temperature and then isothermal for 2 hours; simultaneously, in a third temperature rising stage, oscillating shearing is applied to the raw material mixture, and the amplitude of the oscillating shearing is 8%;

and S3, continuously heating the reaction kettle for 2 hours at 200 ℃ after pressure relief, and then cooling and discharging to obtain a primary material PA 1012.

Putting a polyamide material PA1012 into a vacuum oven, drying for 9h at the temperature of 100 ℃, determining that the weight of the PA1012 does not change any more through a constant weight method test, taking out the PA1012, putting into solid-phase tackifying equipment, performing post polymerization at the temperature of 145 ℃, maintaining the solid-phase tackifying equipment in a vacuum state in the post polymerization process, wherein the post polymerization time is 3h, and cooling to room temperature after the post polymerization is finished to obtain the polyamide material with the gamma crystal form.

The results of mechanical property tests on the polyamide material with the gamma crystal form prepared in the above examples are shown in the following table, and it should be noted that the elongation at break and the toughness in the table refer to the ratio of performance improvement compared with the performance of a polyamide material prepared by the same preparation process without oscillation shearing treatment:

further analysis of the following experimental examples shows that the elongation at break and the toughness in the following tables refer to the ratio of the performance improvement compared to the performance of the polyamide material prepared by the same preparation process without the oscillating shear treatment.

Experimental example 1

In this experimental example, based on the first example, only the amplitude during the preparation process is changed to obtain different polyamide materials, and the specific amplitude during the preparation process of each polyamide material and the properties of the obtained polyamide material are shown in the following table:

amplitude of vibration	Rate of increase of elongation at break	Improvement rate of toughness	Light transmittance%
				10％	60％	60％	80％
20％	105％	90％	90％
				30％	80％	80％	80％
35％	70％	70％	60％
				1％	10％	5％	50％
0％	0％	0％	40％

From the above comparison results, it can be seen that: the polyamide material with a gamma crystal form can be obtained by controlling the oscillation shearing treatment, and the tensile strength and the toughness of the polyamide material are obviously improved compared with the polyamide material obtained without the oscillation shearing treatment; and has higher light transmittance; moreover, it can be further seen that the amplitude applied in the polycondensation reaction process is too small, which does not play a role in regulating and controlling the crystal form, so that the improvement of elongation at break, toughness and light transmittance is limited; meanwhile, the amplitude is not larger and better, and the elongation at break, the toughness and the light transmittance are integrally increased and then decreased along with the increase of the amplitude, which indicates that the applied amplitude is too large, so that the product is degraded, and the final performance of the polyamide material is also influenced.

Second example of experiment

In this experimental example, based on the first example, only the temperature of each temperature rising stage in the preparation process is changed to obtain different polyamide materials, and the specific amplitude in the preparation process of each polyamide material and the properties of the obtained polyamide material are shown in the following table:

from the above comparison results, it can be seen that: in the range of 260-280 ℃, the formation of the gamma crystal form can be promoted by increasing the temperature, so as to improve the performance of the polyamide material, and the performance is rather reduced when the temperature reaches 290 ℃, and in combination with the fact that the polyamide material prepared in the first embodiment is PA66, and the melting temperature is 257 ℃, when the temperature of the polycondensation reaction is between 20 ℃ below the melting temperature and 30 ℃ above the melting temperature, the generation of the gamma crystal form can be significantly influenced, and outside the temperature range, although the gamma crystal form is generated, the gamma crystal form is decomposed due to too high temperature, or the vibration shearing effect is influenced due to too low temperature, so that the performance of the material is reduced.

Meanwhile, the smooth generation of the gamma crystal form is facilitated by a three-stage heating mode, and the performance of the polyamide material prepared by adopting one-step heating is obviously reduced.

EXAMPLE III

In this experimental example, based on the first example, only the duration of each temperature-rising stage in the preparation process is changed to obtain different polyamide materials, and the specific amplitude in each preparation process of the polyamide material and the properties of the obtained polyamide material are shown in the following table:

from the above comparison results, it can be seen that:

when the vibration shearing is applied to the raw material mixture in the second heating stage, the product is degraded due to the long vibration shearing time.

Experimental example four

The experimental examples are based on the first example, and are different in that different polyamide materials are obtained by changing the number of temperature raising stages and the number of temperature raising stages for performing the oscillating shearing treatment, and the specific amplitude in the preparation process of each polyamide material and the performance of the obtained polyamide material are shown in the following table:

from the above comparison results, it can be seen that: the gamma crystal form can be formed in the polyamide material through the oscillation shearing treatment, so that the mechanical property and the light transmittance of the polyamide material are improved, and the performance of the polyamide material can be obviously influenced by changing the distribution of the oscillation shearing duration under the condition of a certain oscillation shearing duration; if the oscillating shearing is concentrated in the second temperature rise stage, the system in the reaction kettle can not be ensured to be in a sheared state before the polycondensation reaction is finished, and further a stable gamma crystal form can not be generated; furthermore, the communicated oscillation shearing time length is divided into two parts, oscillation shearing is carried out in the second temperature rise stage and the third temperature rise stage respectively, and the performance of the polyamide material can be further improved by reasonably distributing the oscillation shearing time lengths in the two temperature rise stages; the long time is distributed to the second heating stage, the short vibration shearing time is distributed to the third heating stage, and the temperature of the third heating stage is higher, so that the short vibration shearing avoids product degradation caused by long-time vibration shearing while promoting the generation of gamma crystals, and the performance of the obtained polyamide material is better.

Experimental example five

In this experimental example, different polyamide materials were obtained by changing only the temperature of the post-polymerization reaction based on the preparation method of example seven, and the specific temperature during the post-polymerization reaction and the properties of the obtained polyamide materials are shown in the following table:

from the above comparison results, it can be seen that: the post-polymerization temperature has obvious influence on the generation of the gamma crystal form, and the higher the post-polymerization temperature is, the improvement of the gamma crystal form in the amide is facilitated, and the mechanical property and the light transmittance of the material are further improved.

Experimental example six

In this example, based on the preparation method of the fifteenth embodiment, different polyamide materials are obtained by changing the cooling rate, and the specific cooling rate and the performance of the obtained polyamide material are shown in the following table:

cooling rate (%/min)	Rate of increase of elongation at break	Improvement rate of toughness	Light transmittance%
				60	103％	60％	95％
100	110％	100％	90％
				Quenching with liquid nitrogen	110％	100％	95％
20	40％	30％	50％
				40	60％	50％	60％
5	0％	0％	20％

From the above comparison results, it can be seen that: the cooling rate also has a great influence on the generation of the gamma crystal form, because the order of subsequent hydrogen bonds can be controlled by changing the cooling rate, and it can be further seen that the faster the cooling rate is, the better the performance of the polyamide material is.

EXAMPLE seventy

In this experimental example, different polyamide materials were obtained by changing the target temperature of temperature reduction based on the preparation method of example fifteen, and the specific target temperature of temperature reduction and the properties of the obtained polyamide material are shown in the following table:

from the above comparison results, it can be seen that: the difference in target temperature to which the temperature is lowered at a particular cooling rate also affects the performance of the material, with lower target temperatures providing better performance of the polyamide material, indicating more gamma crystals are generated internally.

Although the present invention has been described with reference to a preferred embodiment, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A preparation method of a high-transparency high-toughness polyamide material is characterized by comprising the following steps of,

preferably, the antioxidant is one or more of a mixture of phenolic antioxidant, amine antioxidant, metal ion deactivator, or peroxide decomposer;

more preferably, the phenolic antioxidant is antioxidant 1010, antioxidant 1098, antioxidant 1035 or antioxidant 1093; the amine antioxidant is antioxidant DNP or antioxidant 4010; the metal ion passivator is copper acetate/potassium iodide; the peroxide decomposer is an antioxidant 168;

preferably, the catalyst is sodium hypophosphite.

2. The method for preparing the high-transparency high-toughness polyamide material as claimed in claim 1, wherein in step S2, the temperature of the polycondensation reaction is raised from room temperature to a first preset temperature, the first preset temperature is between 80 ℃ below the melting temperature of the polyamide material with the gamma crystal form and the initial thermal decomposition temperature, and after the temperature of the polycondensation reaction reaches the melting temperature of the polyamide material with the gamma crystal form, the raw material mixture is subjected to oscillation shearing treatment;

preferably, the first preset temperature is between 20 ℃ below and 30 ℃ above the melting temperature of the polyamide material with gamma crystallographic form.

3. The method for preparing the high-transparency high-toughness polyamide material according to claim 2, wherein in the step S2, in the polycondensation reaction process, the polycondensation reaction temperature is raised to a first preset temperature by using a stepwise temperature rise manner, wherein the temperature of at least one temperature rise stage is higher than the melting temperature of the polyamide material with the gamma crystal form;

preferably, the segmented temperature rise process at least comprises two temperature rise stages which are higher than the melting temperature of the polyamide material with the gamma crystal form, wherein at least one temperature rise stage carries out oscillation shearing treatment;

more preferably, the last temperature rise stage is subjected to oscillation shearing treatment;

preferably, the temperature rise stage comprises a first temperature rise stage, a second temperature rise stage and a third temperature rise stage, wherein the temperatures of the first temperature rise stage, the second temperature rise stage and the third temperature rise stage are sequentially increased, the oscillation shearing processing is carried out in the second temperature rise stage and the third temperature rise stage, and the oscillation shearing processing time length of the third temperature rise stage is shorter than that of the second temperature rise stage.

4. The method for preparing high-transparency high-toughness polyamide material according to claim 3, wherein the duration of each temperature rise stage is in the range of 1-5h; the total duration of the vibration shearing treatment is not more than 2h; the amplitude range of the oscillating shearing treatment is 3-30%;

preferably, the duration of each temperature rise stage is 2-3h; the total duration of the vibration shearing treatment is 0.5-1h; the amplitude range of the oscillating shearing treatment was 20%.

5. The method for preparing a high-transparency high-toughness polyamide material according to any one of claims 1 to 4, wherein in step S2, the inert gas is used to replace air before the temperature is raised, a part of the inert gas is reserved to reach a preset pressure, and then the temperature is raised to perform polycondensation reaction, wherein the preset pressure is in a range of 0.05 to 1.0MPa.

6. A preparation method of a high-transparency high-toughness polyamide material is characterized in that the polyamide material is subjected to post-polymerization reaction, and the polyamide material with a gamma crystal form is prepared by adjusting the temperature of the post-polymerization reaction, wherein the temperature in the post-polymerization reaction process is between the glass transition temperature and the melting temperature of the polyamide material;

preferably, the polyamide material prepared by the preparation method of any one of claims 1 to 5 is put into solid-phase tackifying equipment for post-polymerization reaction;

preferably, the length of the post-polymerization reaction is 1 to 14 hours;

more preferably, the length of the postpolymerization is from 2 to 8 hours.

7. A preparation method of a high-transparency high-toughness polyamide material is characterized in that after the polyamide material is completely dehydrated, the polyamide material is heated to a temperature higher than a melting point in an inert atmosphere to eliminate heat history, and air is continuously replaced before and in the heating process to keep the inert atmosphere; then cooling to below 40 ℃ below the melting point of the polyamide material at a speed of not less than 5 ℃/min to obtain the polyamide material with a gamma crystal form;

or after the polyamide material is completely dehydrated, heating to a second preset temperature in an inert atmosphere, then carrying out heat treatment on the polyamide material by heat preservation, and then cooling to a temperature lower than the melting point of the polyamide material by 40 ℃ at a speed of not less than 5 ℃/min to obtain the polyamide material with a gamma crystal form;

the inert atmosphere is high-purity helium, high-purity nitrogen or high-purity argon;

preferably, the inert atmosphere is high-purity helium or high-purity nitrogen;

8. The method for preparing the high-transparency high-toughness polyamide material as claimed in claim 7, wherein the second preset temperature is between the melting temperature of the polyamide material and 30 ℃ above the melting temperature, and the heat treatment time is 5-30min.

9. The method for preparing a high-transparency high-toughness polyamide material as claimed in any one of claims 1 to 8, wherein the prepared polyamide material with gamma crystal form is one of PA66, PA610 and PA612, or polyamide with the number of methylene groups between adjacent amide groups on the main chain not less than 10;

preferably, the prepared polyamide material with the gamma crystal form is one of PA1010, PA1012, PA1210, PA1212 or PA 1214.

10. A high-transparency high-toughness polyamide material prepared by the preparation method as claimed in any one of claims 1 to 9, wherein the elongation at break of the polyamide material with the gamma crystal form is 101 to 210% of that of the conventional polyamide material, the toughness is 101 to 200% of that of the conventional polyamide material, and the light transmittance is 80 to 100%.