WO2022237827A1

WO2022237827A1 - Aromatic polyoxadiazole, and aromatic polyoxadiazole film and preparation method therefor

Info

Publication number: WO2022237827A1
Application number: PCT/CN2022/092156
Authority: WO
Inventors: 陈瑾
Original assignee: 陈瑾
Priority date: 2021-05-13
Filing date: 2022-05-11
Publication date: 2022-11-17
Also published as: CN112979947A; CN112979947B

Abstract

The present invention relates to the technical field of polymer materials, and in particular to an aromatic polyoxadiazole, and an aromatic polyoxadiazole film and a preparation method therefor. The aromatic polyoxadiazole comprises a repeating unit A and a repeating unit B; the structure of the repeating unit A is shown in formula I; the structure of the repeating unit B is at least one of formula II, formula III, and formula IV. The aromatic polyoxadiazole film obtained according to the technical solution provided by the present invention has high light transmittance. In the wavelength range of 400-800 nm, the light transmittance exceeds 85%, and the maximum light transmittance reaches 94%.

Description

Aromatic polyoxadiazole, aromatic polyoxadiazole film and film preparation method

technical field

The invention belongs to the technical field of polymer materials, and in particular relates to an aromatic polyoxadiazole, an aromatic polyoxadiazole film and a preparation method of the film.

Background technique

Aromatic polyoxadiazole is a high-performance polymer containing benzene ring and oxadiazole ring in the molecular chain. Because of its good high temperature resistance, chemical resistance and electrical insulation, aromatic polyoxadiazole is It is used in various fields, such as the field of high temperature resistance and the field of electrical insulation protection. However, its dark color and low light transmittance severely limit its application in the field of optoelectronics.

technical problem

In the prior art, the flame retardancy of aromatic polyoxadiazoles is mostly improved, and there are few reports on the study of their optical properties. In order to make aromatic polyoxadiazoles better applied in various fields, research And it is very necessary to prepare aromatic polyoxadiazole materials with high light transmittance.

technical solution

In view of the above-mentioned deficiencies existing in the prior art, the object of the present invention is to provide a kind of preparation method of aromatic polyoxadiazole, aromatic polyoxadiazole film and film, described aromatic polyoxadiazole film has high transparency Light rate, in the wavelength range from 400nm to 800nm, the light transmittance exceeds 85%, and the maximum light transmittance reaches 94%.

For realizing above-mentioned purpose of the invention, the technical scheme that the present invention adopts is as follows:

In the first aspect, the present invention provides an aromatic polyoxadiazole, the aromatic polyoxadiazole includes a repeating unit A and a repeating unit B, and the structure of the repeating unit A is shown in formula I:

The structure of the repeating unit B is at least one of formula II, formula III, and formula IV:

R is one of the metal elements of the first main group;

The aromatic polyoxadiazole is obtained by polycondensation reaction in fuming sulfuric acid with terephthalic acid, phthalic acid derivatives and hydrazine salt as reaction raw materials, and the phthalic acid derivative is 2-fluoropara At least one of phthalic acid, 5-fluoroisophthalic acid, and isophthalic acid-5-sulfonate, the molar ratio of oleum, terephthalic acid, phthalic acid derivatives, and hydrazine salt Be (4～7): (0.7～0.8): (0.2～0.3): (1～1.5), wherein, the molar number of described fuming sulfuric acid is contained in the described fuming sulfuric acid SO _The molar number count.

The invention provides aromatic polyoxadiazoles in which 2-fluoroterephthalic acid, 5-fluoroisophthalic acid or isophthalic acid-5-sulfonate monomers participate in copolymerization, which significantly improves the aromatic polyoxadiazole The transmittance of azoles.

In the second aspect, the present invention provides an aromatic polyoxadiazole film prepared from the aromatic polyoxadiazole described in the first aspect.

The aromatic polyoxadiazole film has high light transmittance, and in the wavelength range of 400nm to 800nm, the light transmittance exceeds 85%, and the maximum light transmittance reaches 94%.

In a third aspect, the present invention provides a method for preparing the aromatic polyoxadiazole film as described in the second aspect, said method comprising the following steps:

S1 takes terephthalic acid, phthalic acid derivatives and hydrazine salts as reaction raw materials, and carries out polycondensation reaction in oleum to obtain an aromatic polyoxadiazole solution, and the phthalic acid derivative is 2-fluoroparaphenylene At least one of dicarboxylic acid, 5-fluoroisophthalic acid, and isophthalic acid-5-sulfonate;

S2 Extrude the aromatic polyoxadiazole solution through a hanger-type die, and then transport it to the first-stage coagulation bath, the second-stage coagulation bath, and the third-stage coagulation bath for coagulation and molding to obtain coagulated acid-containing wet State primary casting film, each level of coagulation bath includes sulfuric acid and water, the weight ratio of sulfuric acid and water in the first level coagulation bath is (30:70) ~ (50:50), the second level The weight ratio of sulfuric acid and water in the secondary coagulation bath is (20:80)～(25:75), and the weight ratio of the sulfuric acid and water in the described tertiary coagulation bath is (2:98)～(8: 92);

S3 washing the acid-containing wet-state primary cast film to obtain a sulfuric acid-free primary cast film;

S4 Biaxially stretching the primary casting film not containing sulfuric acid, then performing heat setting treatment at 300-450° C., trimming, and winding to obtain the aromatic polyoxadiazole film.

Preferably, in step S1, the molar ratio of the oleum, terephthalic acid, phthalic acid derivatives and hydrazine salt is (4-7): (0.7-0.8): (0.2-0.3): (1～1.5), wherein, the molar number of fuming sulfuric acid is SO contained in the fuming sulfuric acid ₃ The molar number of meter.

In any of the above schemes, preferably, the hydrazine salt is hydrazine sulfate or hydrazine hydrochloride, and the content of sulfur trioxide in the oleum is 20-40wt%.

Preferably in any of the above schemes, the polycondensation reaction is carried out in three stages:

The first stage: the reaction temperature is 90~130℃, and the reaction time is 3~5h;

The second stage: the reaction temperature is 140-170°C, the reaction time is 2-6 hours, and the chain terminator is added when the second stage is completed;

The third stage: the reaction temperature is 150-180°C, and the reaction time is 3-6 hours.

In any of the above schemes, preferably, the chain terminator is benzoic acid, and the added amount of the chain terminator is 0.5% to 2% of the moles of the hydrazine salt in the reaction system of the polycondensation reaction.

In any of the above schemes, it is preferred that the extrusion process of the hanger type die is: the aromatic polyoxadiazole solution is degassed, then sent to a coarse filter for coarse filtration, and then sent to a fine filter The filter is used for fine filtration, and then sent to the hanger mold, extruded from the mold slit to the solidified roller to form a sheet-like polyoxadiazole solution.

In any of the above schemes, it is preferable that the filter mesh diameter of the coarse filter is 50 μm-70 μm, and the filtration pressure is ≤1.0 MPa; the filter mesh diameter of the fine filter is 40 μm-50 μm, and the filtration pressure is ≤2.0 MPa.

Preferably in any of the above schemes, in step S2, the weight ratio of sulfuric acid and water in the first-stage coagulation bath is (38:62)～(42:58), and in the second-stage coagulation bath The weight ratio of sulfuric acid and water is (22:78)～(24:76), and the weight ratio of sulfuric acid and water in the third stage coagulation bath is (4:96)～(6:94).

Preferably in any of the above schemes, in step S2, the reaction temperature of the aromatic polyoxadiazole solution in each stage of the coagulation bath is 40°C-70°C, and the reaction time is 3-10°C. minute.

Preferably in any of the above-mentioned schemes, the described acid-containing wet state primary casting film is washed and comprises the following steps:

After the acid-containing wet primary cast film is washed in the first stage, alkali washed, and washed in the second stage, the primary cast film without sulfuric acid is obtained;

The alkali washing adopts an aqueous solution of sodium hydroxide or sodium bicarbonate with a mass fraction of 1% to 5%; the time of the first-stage water washing and the second-stage water washing is 5-20 minutes, and the temperature is 40-70°C. °C; the time for the alkali washing is 5-20 minutes, and the temperature is 40-70 °C.

Preferably in any of the above schemes, in step S4, the biaxial stretching process is: biaxially stretching the sulfuric acid-free nascent cast film in a biaxial stretching device for 1 to 3 times, The stretching temperature is 100°C to 150°C.

In any of the above schemes, it is preferred that in step S2, the aromatic polyoxadiazole solution is completely formed on the forming roller, and the material of the forming roller is glass, ceramics, Hastelloy or 904L stainless steel, and the The surface roughness of the forming roller is Ra<0.4.

In any of the above schemes, preferably, the residence time of the aromatic polyoxadiazole solution on the forming roller is 10-90 seconds.

In any of the above schemes, it is preferred that the coagulation bath at each level also contains sulfate, and the amount of the sulfate added is 0.2% to 20% of the moles of sulfuric acid in the coagulation bath at each level.

Preferably in any of the above schemes, the sulfate is at least one of sodium sulfate and potassium sulfate.

Preferably in any of the above schemes, the following steps are also included before the winding:

Tempering treatment is carried out at 250°C to 300°C.

The preparation method provided by the invention has simple steps, convenient operation and control, stable quality, high production efficiency, low production cost, and large-scale industrial production. The aromatic polyoxadiazole film prepared according to the preparation method not only has excellent mechanical properties , also has a high light transmittance.

Beneficial effect

BEST MODE FOR CARRYING OUT THE INVENTION

In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer, the present invention will be further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

Unless otherwise defined, the technical terms used in the following embodiments have the same meaning as commonly understood by those skilled in the art to which the present invention belongs. The reagents used in the following examples, unless otherwise specified, are conventional biochemical reagents; the raw materials, instruments and equipment etc. used in the following examples can be purchased from the market or obtained by existing methods; the reagent consumption , unless otherwise specified, are all reagent dosages in conventional experimental operations; said experimental methods, unless otherwise specified, are conventional methods.

In the first aspect, an embodiment of the present invention provides an aromatic polyoxadiazole, the aromatic polyoxadiazole includes a repeating unit A and a repeating unit B, and the structure of the repeating unit A is shown in Formula I:

R is one of the metal elements of the first main group;

R is one of the metal elements of the first main group, for example, R can be lithium, sodium or potassium.

Embodiments of the present invention provide aromatic polyoxadiazoles in which 2-fluoroterephthalic acid, 5-fluoroisophthalic acid or isophthalic acid-5-sulfonate monomers participate in copolymerization, which significantly improves the aromatic polyoxadiazole The light transmittance of oxadiazole.

In a second aspect, an embodiment of the present invention provides an aromatic polyoxadiazole film prepared from the aromatic polyoxadiazole described in the first aspect.

The aromatic polyoxadiazole film can be applied to but not limited to the field of optoelectronics, cover film, fuel cell stack proton exchange membrane, chip carrier film, high temperature tape substrate, TFT substrate, flexible display substrate, LED light strip Substrate, FPC substrate, graphite heat dissipation film substrate, lithium battery diaphragm, aerospace military industry.

In a third aspect, an embodiment of the present invention provides a method for preparing an aromatic polyoxadiazole film as described in the second aspect, the method comprising the following steps:

The aromatic polyoxadiazole can be prepared through step S1.

In the embodiments of the present invention, by selecting the number of coagulation bath stages and component concentrations, the concentration difference between sulfuric acid in the film and the sulfuric acid in the coagulation bath is reduced, the impact of the sulfuric acid precipitation process on the film is weakened, the precipitation time of sulfuric acid is prolonged, and the sulfuric acid in the film is reduced. The precipitation is more thorough, and the prepared film not only has excellent mechanical properties, but also has high light transmittance.

The thickness of the film prepared according to the preparation method provided in the embodiment of the present invention is 5-800 μm.

The preparation method provided by the embodiment of the present invention has simple steps, convenient operation and control, stable quality, high production efficiency, low production cost, and large-scale industrial production.

The structure of the 2-fluoroterephthalic acid is shown in formula V:

The structure of the 5-fluoroisophthalic acid is shown in formula VI:

The isophthalic acid-5-sulfonate can be isophthalic acid-5-sodium sulfonate, the structure of which is shown in formula VII:

Further, in step S1, the molar ratio of the oleum, terephthalic acid, phthalic acid derivatives and hydrazine salt is (4-7): (0.7-0.8): (0.2-0.3): ( 1～1.5), wherein, the number of moles of fuming sulfuric acid is calculated in the number _of moles of SO3 contained in the fuming sulfuric acid, if described phthalic acid derivatives are used too much, then the mechanical property of the film that obtains declines obviously, if If the amount of the phthalic acid derivative is too small, the light transmittance of the film cannot be significantly improved. For example, the molar ratio of oleum, terephthalic acid, phthalic acid derivatives and hydrazine salt can be 4:0.7:0.3:1.1, 5:0.8:0.2:1.2 or 7:0.8:0.2:1.4, etc.

Further, the hydrazine salt is hydrazine sulfate or hydrazine hydrochloride, and the content of sulfur trioxide in the oleum is 20-40wt%, for example, the content can be 20wt%, 30wt% or 40wt%.

Further, the polycondensation reaction is carried out in three stages:

The first stage: the reaction temperature is 90-130°C (for example, the reaction temperature can be 90°C, 100°C, 110°C, 120°C or 130°C, etc.), and the reaction time is 3-5h (for example, the reaction time can be 3h, 4h or 5h, etc.);

The second stage: the reaction temperature is 140-170°C (for example, the reaction temperature can be 140°C, 150°C or 170°C, etc.), the reaction time is 2-6h (for example, the reaction time can be 3h, 4h or 5h, etc.), and The chain terminator is added at the completion of the second stage;

The third stage: the reaction temperature is 150-180°C (for example, the reaction temperature can be 150°C, 170°C or 180°C, etc.), and the reaction time is 3-6h (for example, the reaction time can be 3h, 4h or 5h, etc.).

The first stage is prepolymerization, the second stage is polymerization, and the third stage is cyclization.

Further, the chain terminator is benzoic acid, and the added amount of the chain terminator is 0.5% to 2% of the moles of the hydrazine salt in the reaction system of the polycondensation reaction, for example, if the hydrazine salt in the reaction system The amount of salt is 100 mol, then the amount of the chain terminator added can be 0.5 mol, 1 mol, 1.5 mol or 2 mol, etc.

Further, the extrusion process of the hanger type die is as follows: the aromatic polyoxadiazole solution is subjected to defoaming treatment, then transported to a coarse filter for coarse filtration, then transported to a fine filter for fine filtration, and then sent to To the hanger type mold, extruded in the mold slit to the solidification roller to form a sheet polyoxadiazole solution.

Further, the pore size of the filter mesh of the coarse filter is 50 μm to 70 μm (for example, the pore size can be 50 μm, 60 μm or 70 μm, etc.), the filtration pressure is ≤ 1.0 MPa, and the filter mesh diameter of the fine filter is 40 μm to 50 μm (for example, The pore size can be 40μm, 42μm, 44μm, 46μm or 50μm, etc.), and the filtration pressure is ≤2.0MPa.

Further, in step S2, the weight ratio of sulfuric acid and water in the first-stage coagulation bath is (38:62)-(42:58), for example, the weight ratio can be 38:62, 40:60 or 42 :58 etc.

Further, in step S2, the weight ratio of sulfuric acid and water in the second-stage coagulation bath is (22:78)～(24:76), for example, the weight ratio can be 22:78, 23:77 or 24 :76 etc.

Further, in step S2, the weight ratio of sulfuric acid and water in the third coagulation bath is (4:96)～(6:94), for example, the weight ratio can be 4:96, 5:95 or 6 :94 etc.

Further, in step S2, the reaction temperature of the aromatic polyoxadiazole solution in each stage of the coagulation bath is 40°C-70°C, for example, the temperature can be 40°C, 50°C, 60°C or 70°C, etc., as the temperature of the coagulation bath increases, the proportion of coarse crystals in the film crystal decreases, the proportion of microcrystals increases, the arrangement is more orderly, and the light transmittance increases, but the mechanical properties decrease. In order to ensure that the film has excellent mechanical properties and transmits The rate is relatively high, preferably, the temperature is 45°C to 50°C.

Further, in step S2, the reaction time of the aromatic polyoxadiazole solution in each stage of the coagulation bath is 3 to 10 minutes, for example, the reaction time can be 3 minutes, 5 minutes, 7 minutes or 10 minutes wait.

Further, the washing of the acid-containing wet primary cast film comprises the following steps:

After the acid-containing wet primary cast film is washed with water in the first stage, washed with alkali, and washed with water in the second stage, the primary cast film without sulfuric acid is obtained.

Further, the alkali washing adopts an aqueous solution of sodium hydroxide or sodium bicarbonate with a mass fraction of 1% to 5%, for example, the mass fraction may be 1%, 2%, 4% or 5%.

Further, the time for the first-level water washing, the second-level water washing and the alkali washing is all 5 to 20 minutes (for example, the time can be 5 minutes, 10 minutes, 15 minutes or 20 minutes, etc.), and the temperature is 40 ~70°C (for example, the temperature can be 40°C, 50°C, 60°C or 70°C, etc.).

Further, in step S4, the process of biaxial stretching is: carry out 1 to 3 times (for example, 1 time, 2 times or 3 times) of the primary casting film without sulfuric acid in a biaxial stretching device times, etc.), the stretching temperature is 100°C to 150°C (for example, the temperature can be 100°C, 110°C, 120°C, 130°C, 140°C or 150°C, etc.).

Further, in step S2, the aromatic polyoxadiazole solution is completely formed on the forming roller, the material of the forming roller is glass, ceramics, Hastelloy or 904L stainless steel, and the surface roughness of the forming roller is Ra<0.4.

Further, the residence time of the aromatic polyoxadiazole solution on the forming roller is 10 to 90 seconds, for example, the residence time can be 10 seconds, 20 seconds, 30 seconds, 40 seconds, 50 seconds, 60 seconds, 70 seconds seconds, 80 seconds, or 90 seconds, etc., the residence time refers to the time from when the aromatic polyoxadiazole solution passes through each stage of the coagulation bath to the forming roll until the film can be peeled off from the forming roll without sticking. Time elapsed for roll residue to end.

Further, sulfate is also included in the coagulation bath at each level, and the addition amount of the sulfate is 0.2% to 20% of the molar number of sulfuric acid in the coagulation bath at each level, such as the addition amount of the sulfate 0.2%, 2%, 5%, 10%, 15% or 20% of the sulfuric acid mole in the coagulation bath, preferably 3% to 5%. Adding sulfate to the coagulation bath can make the film smoother , easier to peel off from the forming roll.

Further, the sulfate is at least one of sodium sulfate and potassium sulfate.

Further, the following step is also included before the winding, performing tempering treatment at 250° C. to 300° C., and the stress of the edge film can be relieved after the tempering treatment.

Further, in step S4, heat setting treatment at 300-450°C (for example, 300°C, 350°C, 400°C or 450°C, etc.) is beneficial to improve the high temperature resistance of the film, reduce the coefficient of thermal expansion (CTE), and improve Dimensional stability.

Example

The present invention has been tested many times successively, and a part of the test results are given as a reference to further describe the invention in detail, and will be described in detail below in conjunction with specific examples.

Fuming sulfuric acid: SO ₃ mass percentage content is 20% fuming sulfuric acid.

Example 1

S1: Mix fuming sulfuric acid, terephthalic acid, sodium 5-sulfonate isophthalate, and hydrazine sulfate at a molar ratio of 5:0.7:0.3:1.2 for polycondensation reaction to obtain an aromatic polyoxadiazole solution.

The polycondensation reaction is carried out in three stages: the first stage: the reaction temperature is 100°C, the reaction time is 4h; the second stage: the reaction temperature is 145°C, the reaction time is 4h, and benzoic acid is added when the second stage is completed , the addition of the benzoic acid is 1% of the molar number of hydrazine sulfate in the reaction system of the polycondensation reaction; the third stage: the reaction temperature is 170°C, and the reaction time is 5h.

S2: The aromatic polyoxadiazole solution is defoamed, then sent to the coarse filter for coarse filtration, then sent to the fine filter for fine filtration, and then accurately metered by the gear metering pump and sent to the hanger mold , Extruded in the die slit to the solidified roller to form a sheet polyoxadiazole solution. The coarse filter has a filter mesh diameter of 60 μm and a filtration pressure of ≤1.0 MPa, and the fine filter has a filter mesh diameter of 40 μm and a filtration pressure of ≤2.0 MPa.

The flaky polyoxadiazole solution is sequentially transported to the first stage coagulation bath (reaction temperature is 45°C, reaction time is 4 minutes), the second stage coagulation bath (reaction temperature is 45°C, reaction time is 5 minutes) and the third-stage coagulation bath (reaction temperature is 45 ° C, reaction time is 7 minutes) to carry out coagulation molding, to obtain solidified acid-containing wet primary cast film, the coagulation bath of each level is composed of sulfuric acid and water, The weight ratio of the sulfuric acid in the first-level coagulation bath and water is 40:60, the weight ratio of the sulfuric acid in the second-level coagulation bath and water is 23:77, and the sulfuric acid in the third-level coagulation bath The weight ratio with water is 5:95.

The aromatic polyoxadiazole solution is completely formed on the forming roller, the residence time is 40 seconds, and the material of the forming roller is 904L stainless steel.

S3 The acid-containing wet state primary cast film is subjected to the first-stage water washing (the temperature is 45° C., and the time is 10 minutes), the alkali washing (the temperature is 45° C., the time is 15 minutes), and the second-stage water washing (the temperature is 10 minutes). 45° C. for 15 minutes), to obtain a primary casting film not containing sulfuric acid, and the alkali washing adopts a 1% sodium hydroxide aqueous solution by mass fraction.

S4 The sulfuric acid-free nascent casting film is biaxially stretched twice at 110°C in a biaxial stretching device and dried, controlling the moisture content of the film to be below 10%, and then performing heat setting treatment at 400°C , and trimming and winding to obtain the aromatic polyoxadiazole film.

The performance parameters of the film are: the thickness of the finished film is 25 μm, the limiting oxygen index is 40%, the tensile strength is 180 MPa, the elongation at break is 80%, and the light transmittance exceeds 90% in the wavelength range of 400nm to 800nm, the maximum The light transmittance reaches 94%, and the light transmittance at a wavelength of 550nm is 92%.

It can be seen from the performance parameters that the film not only has good mechanical properties and flame retardant properties, but also has high light transmittance.

Example 2

It is basically the same as step S1 in Example 1, except that 5-sodium sulfoisophthalate is replaced by 2-fluoroterephthalic acid.

It is exactly the same as steps S2-S4 in embodiment 1.

The performance parameters of the film are: the thickness of the finished film is 25 μm, the limiting oxygen index is 34%, the tensile strength is 190 MPa, the elongation at break is 82%, and the light transmittance exceeds 85% in the wavelength range of 400nm to 800nm, the maximum The light transmittance reaches 89%, and the light transmittance at a wavelength of 550nm is 87%.

Example 3

It is basically the same as step S1 in Example 1, except that 5-sodium sulfoisophthalate is replaced by 5-fluoroisophthalic acid.

It is exactly the same as steps S2-S4 in embodiment 1.

The performance parameters of the film are: the thickness of the finished film is 25 μm, the limiting oxygen index is 36%, the tensile strength is 182 MPa, the elongation at break is 81%, and the light transmittance exceeds 87% in the wavelength range from 400nm to 800nm, the maximum The light transmittance reaches 91%, and the light transmittance at a wavelength of 550nm is 89%.

Comparative example 1

It is basically the same as step S1 in Example 1, except that oleum, terephthalic acid and hydrazine sulfate are mixed according to the molar ratio of 5:1:1.2 to carry out polycondensation reaction.

It is exactly the same as steps S2-S4 in embodiment 1.

The performance parameters of the film are: the thickness of the finished film is 25 μm, the limiting oxygen index is 21%, the tensile strength is 200 MPa, the elongation at break is 85%, and the light transmittance exceeds 60% in the wavelength range from 400nm to 800nm, the maximum The light transmittance reaches 65%, and the light transmittance at a wavelength of 550nm is 61%.

Comparative example 2

It is exactly the same as step S1 in embodiment 1.

It is basically the same as step S2 in Example 1, except that the sheet-shaped polyoxadiazole solution is only transported to the first-stage coagulation bath (reaction temperature is 45°C, reaction time is 15 minutes) for coagulation and molding, so The weight ratio of sulfuric acid and water in the first stage coagulation bath is 40:60.

It is exactly the same as steps S3 and S4 in Embodiment 1.

The performance parameters of the film are: the thickness of the finished film is 25 μm, the limiting oxygen index is 39%, the tensile strength is 150 MPa, the elongation at break is 63%, and the light transmittance exceeds 79% in the wavelength range of 400nm to 800nm, the maximum The light transmittance reaches 83%, and the light transmittance at a wavelength of 550nm is 81%.

Comparative example 3

It is exactly the same as step S1 in embodiment 1.

It is basically the same as step S2 in Example 1, except that the reaction temperature of each coagulation bath is 55°C.

It is exactly the same as steps S3 and S4 in Embodiment 1.

The performance parameters of the film are: the thickness of the finished film is 25 μm, the limiting oxygen index is 37%, the tensile strength is 150 MPa, the elongation at break is 63%, and the light transmittance exceeds 90% in the wavelength range of 400nm to 800nm, the maximum The light transmittance reaches 93%, and the light transmittance at a wavelength of 550nm is 91%.

It can be seen from the performance parameters of the film that compared with Example 1, the light transmittance is not much different, and the mechanical properties are significantly reduced.

Comparative example 4

It is basically the same as step S1 in Example 1, except that the molar ratio of oleum, terephthalic acid, isophthalic acid-5-sodium sulfonate and hydrazine sulfate is 5:0.9:0.1:1.2.

Exactly the same as steps S2～S4 in embodiment 1.

The performance parameters of the film are: the thickness of the finished film is 25 μm, the limiting oxygen index is 37%, the tensile strength is 185 MPa, the elongation at break is 82%, and the light transmittance exceeds 76% in the wavelength range of 400nm to 800nm, the maximum The light transmittance reaches 81%, and the light transmittance at a wavelength of 550nm is 79%.

It can be seen from the performance parameters that the light transmittance decreases significantly when the dosage of sodium isophthalic acid-5-sulfonate is reduced.

Similarly, if the molar ratio of oleum, terephthalic acid, 2-fluoroterephthalic acid and hydrazine sulfate is 5:0.9:0.1:1.2 or oleum, terephthalic acid, 5-fluoroisophthalic acid When the molar ratio of formic acid and hydrazine sulfate is 5:0.9:0.1:1.2, compared with Example 2 or Example 3, the light transmittance also drops significantly.

Comparative example 5

It is basically the same as Step S1 in Example 1, except that the molar ratio of oleum, terephthalic acid, 5-sodium isophthalic acid and hydrazine sulfate is 5:0.5:0.5:1.2.

Exactly the same as steps S2～S4 in embodiment 1.

The performance parameters of the film are: the thickness of the finished film is 25 μm, the limiting oxygen index is 42%, the tensile strength is 161 MPa, the elongation at break is 68%, and the light transmittance exceeds 90% in the wavelength range of 400nm to 800nm, the maximum The light transmittance reaches 93%, and the light transmittance at a wavelength of 550nm is 91%.

It can be seen from the performance parameters that increasing the amount of sodium isophthalic acid-5-sulfonate does not significantly change the light transmittance of the film, but the mechanical properties significantly decrease.

Similarly, if the molar ratio of oleum, terephthalic acid, 2-fluoroterephthalic acid and hydrazine sulfate is 5:0.5:0.5:1.2 or oleum, terephthalic acid, 5-fluoroisophthalic acid When the molar ratio of formic acid and hydrazine sulfate is 5:0.5:0.5:1.2, compared with Example 2 or Example 3, the light transmittance of the film does not change significantly, but the mechanical properties decrease significantly.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. within range.

Industrial Applicability

The preparation method provided by the invention has simple steps, convenient operation and control, stable quality, high production efficiency, low production cost, and large-scale industrial production. The aromatic polyoxadiazole film prepared according to the preparation method not only has excellent mechanical properties , also has a higher light transmittance.

Claims

A kind of aromatic polyoxadiazole, it is characterized in that, described aromatic polyoxadiazole comprises repeating unit A and repeating unit B, and the structure of described repeating unit A is as shown in formula I:

The structure of the repeating unit B is at least one of formula II, formula III, and formula IV:

R is one of the metal elements of the first main group;

The aromatic polyoxadiazole is obtained by polycondensation reaction in fuming sulfuric acid with terephthalic acid, phthalic acid derivatives and hydrazine salt as reaction raw materials, and the phthalic acid derivative is 2-fluoropara At least one of phthalic acid, 5-fluoroisophthalic acid, and isophthalic acid-5-sulfonate, the molar ratio of oleum, terephthalic acid, phthalic acid derivatives, and hydrazine salt Be (4～7): (0.7～0.8): (0.2～0.3): (1～1.5), wherein, the molar number of described fuming sulfuric acid is contained in the described fuming sulfuric acid SO The molar number count.
An aromatic polyoxadiazole film, characterized in that it is prepared from the aromatic polyoxadiazole described in claim 1.
A preparation method of aromatic polyoxadiazole film as claimed in claim 2, is characterized in that, described method comprises the following steps:

S1 takes terephthalic acid, phthalic acid derivatives and hydrazine salts as reaction raw materials, and carries out polycondensation reaction in oleum to obtain an aromatic polyoxadiazole solution, and the phthalic acid derivative is 2-fluoroparaphenylene At least one of dicarboxylic acid, 5-fluoroisophthalic acid, and isophthalic acid-5-sulfonate;

S2 Extrude the aromatic polyoxadiazole solution through a hanger-type die, and then transport it to the first-stage coagulation bath, the second-stage coagulation bath, and the third-stage coagulation bath for coagulation and molding to obtain solidified acid-containing wet State primary casting film, each level of coagulation bath includes sulfuric acid and water, the weight ratio of sulfuric acid and water in the first level coagulation bath is (30:70) ~ (50:50), the second level The weight ratio of the sulfuric acid in the secondary coagulation bath and water is (20:80)～(25:75), and the weight ratio of the sulfuric acid and water in the described tertiary coagulation bath is (2:98)～(8: 92);

S3 washing the acid-containing wet-state primary cast film to obtain a sulfuric acid-free primary cast film;

S4 Biaxially stretching the primary casting film not containing sulfuric acid, then performing heat setting treatment at 300-450° C., trimming, and winding to obtain the aromatic polyoxadiazole film.
The preparation method of aromatic polyoxadiazole film according to claim 3, is characterized in that, in step S1:

The molar ratio of the oleum, terephthalic acid, phthalic acid derivatives and hydrazine salt is (4～7):(0.7～0.8):(0.2～0.3):(1～1.5), wherein, the The number of moles of said oleum is calculated by the number of moles of SO contained in said fuming sulfuric acid.
The method for preparing an aromatic polyoxadiazole film according to claim 3, wherein the hydrazine salt is hydrazine sulfate or hydrazine hydrochloride, and the content of sulfur trioxide in the oleum is 20-40 wt%.
The preparation method of aromatic polyoxadiazole film according to claim 3, is characterized in that, described polycondensation reaction is carried out in three stages:

The first stage: the reaction temperature is 90~130℃, and the reaction time is 3~5h;

The second stage: the reaction temperature is 140-170°C, the reaction time is 2-6 hours, and the chain terminator is added when the second stage is completed;

The third stage: the reaction temperature is 150-180°C, and the reaction time is 3-6 hours.
The preparation method of aromatic polyoxadiazole film according to claim 6, is characterized in that, described chain terminator is benzoic acid, and the addition amount of described chain terminator is described in the reaction system of described polycondensation reaction 0.5% to 2% of the moles of hydrazine salt.
The preparation method of the aromatic polyoxadiazole film according to claim 3, characterized in that, the extrusion process of the hanger type die is: the aromatic polyoxadiazole solution is subjected to defoaming treatment, and then conveyed It is sent to the coarse filter for coarse filtration, then sent to the fine filter for fine filtration, and then sent to the hanger mold, extruded from the slit of the mold to the solidified roller to form a sheet-like polyoxadiazole solution.
The preparation method of aromatic polyoxadiazole film according to claim 8, characterized in that, the filter screen aperture of the coarse filter is 50 μm to 70 μm, the filtration pressure is ≤1.0 MPa, and the filter screen of the fine filter The pore size is 40μm～50μm, and the filtration pressure is ≤2.0MPa.
The preparation method of aromatic polyoxadiazole film according to claim 3, is characterized in that, also comprises sulfate in the described coagulation bath of each stage, and the addition of described sulfate is the described coagulation bath of each stage. 0.2% to 20% of the moles of sulfuric acid in the medium.