A high intrinsic viscosity polyethylene naphthalate with a branched structure and a preparation method thereof

Abstract

The application discloses high-characteristic-viscosity polyethylene naphthalate with a branched structure and a preparation method thereof, and belongs to the technical field of material chemical industry. The preparation method comprises the following steps: 60-65 parts of dimethyl 2,6-naphthalene dicarboxylate, 35-40 parts of ethylene glycol, 0.1-2 parts of three / four branched monomers, 0.01-0.5 parts of a catalyst and 0.01-0.5 parts of an antioxidant are mixed according to the mass fraction, a polymerization reaction is carried out, methanol is removed, and then ethylene glycol is removed. In the application, the three / four branched monomers are added in a certain amount to form a branched chain structure on the polymer main chain, so that the melt viscosity of the polymer is reduced, which is beneficial to the mass transfer and diffusion of the small-molecule byproduct ethylene glycol, and then is beneficial to the forward progress of the polycondensation reaction, and the reaction time is shortened. The branched structure reduces the viscosity, more byproduct ethylene glycol can be removed, the reaction degree is increased, and the product obtained has a higher characteristic viscosity.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of chemical materials, in particular to a high-characteristic-viscosity polyethylene naphthalate with a branched structure and a preparation method. BACKGROUND

[0002] Flexible electronic devices have unique flexibility, ductility and low-cost manufacturing process, and have wide application prospects in the fields of information, medical treatment, energy and national defense, such as flexible printed circuit boards, flexible electronic display devices, thin-film solar cells and the like. The preparation of flexible electronic devices usually needs to adopt a polymer film as a flexible support material, and the mechanical properties, heat resistance and optical properties of the polymer film will directly affect the safety and service life of the electronic devices. The chemical structure of a PEN resin is similar to that of polyethylene terephthalate (PET), with the difference that the PEN has a larger naphthalene ring instead of a benzene ring in the molecular chain of the PET, and the naphthalene ring structure makes the PEN have more excellent physical and mechanical properties, gas barrier properties, chemical stability and heat resistance, ultraviolet resistance, radiation resistance and the like than the PET, and the PEN is an ideal product for replacing PET thin films used in electronic information.

[0003] Industrial preparation of the PEN resin usually adopts an ester exchange method. Dimethyl 2,6-naphthalene dicarboxylate and ethylene glycol are used as substrates to remove a small-molecule by-product methanol under a high-temperature environment to obtain an intermediate ethylene glycol naphthalate, and then a polycondensation reaction is carried out under a high-temperature and high-vacuum environment to remove a small-molecule by-product ethylene glycol to obtain the product PEN. The polycondensation reaction is a reversible reaction, and the removal speed and degree of the by-product ethylene glycol directly affect the intrinsic viscosity of the product PEN.

[0004] In the later stage of the polymerization reaction, due to the existence of the naphthalene ring in the molecular chain of the polyethylene glycol naphthalate, the naphthalene ring and the carbonyl group in the ester bond structure form a larger conjugated structure, and the conjugated structures between the molecular chains are prone to crystallization due to π-π stacking, or the polymer melt viscosity increases due to the strong interaction between the molecular chains. The increase of the polymer melt viscosity leads to the difficulty in the removal of the small-molecule by-product ethylene glycol, and makes it difficult to improve the intrinsic viscosity of the PEN resin.

[0005] In view of the above problem of difficulty in improving the intrinsic viscosity, domestic and foreign scholars have carried out a large amount of research work, and Chinese patent CN 102766253A discloses a solid-phase polycondensation method. First, dimethyl 2,6-naphthalene dicarboxylate and ethylene glycol are used as substrates to carry out an ester exchange reaction to obtain low-molecular-weight crystal particles with an intrinsic viscosity of 0.35 dL / g, and then a solid-phase polycondensation reaction is carried out at 240-260 DEG C for 24-36 hours to obtain a high-intrinsic-viscosity PEN resin. The resin synthesized by the polymerization method has an intrinsic viscosity of 1.0-1.4 dL / g, but has the defects of long reaction time, high energy consumption and poor economy, and therefore is not the preferred scheme for synthesizing the resin. SUMMARY

[0006] The present application aims at overcoming the problems of long reaction time and difficulty in improving intrinsic viscosity in the prior art for preparing PEN resin, and provides a high intrinsic viscosity polyethylene naphthalate with branched structure and a preparation method.

[0007] To achieve the above object, the technical scheme adopted by the present application is as follows:

[0008] A preparation method of high intrinsic viscosity polyethylene naphthalate with branched structure, comprising the following steps:

[0009] The dimethyl 2,6-naphthalene dicarboxylate 60-65 parts, ethylene glycol 35-40 parts, three / four branched monomer 0.1-2 parts, catalyst 0.01-0.5 parts and antioxidant 0.01-0.5 parts are subjected to polymerization reaction and removal of methanol, and then removal of ethylene glycol, to obtain high intrinsic viscosity polyethylene naphthalate with branched structure.

[0010] Further, the three / four branched monomer is one of 1,3,5-benzene tricarboxylic acid trimethyl ester, 1,2,4-benzene tricarboxylic acid trimethyl ester, 1,3,5-benzene tricarboxylic acid triethyl ester, 1,3,6-naphthalene tricarboxylic acid trimethyl ester, benzene-1,2,4,5-tetracarboxylic acid tetramethyl ester, 1,2,4,5-benzene tetracarboxylic acid tetrabutyl ester and 1,3,5,7-naphthalene tetracarboxylic acid tetramethyl ester or a mixture of two of them.

[0011] Further, the catalyst is one of zinc acetate and antimony trioxide.

[0012] Further, the antioxidant is one of steric phenolic antioxidant 1010 and triphenyl phosphite or a mixture of two of them.

[0013] Further, the polymerization reaction conditions are as follows: reaction temperature is 180-250℃, time is 2.5-5 hours, and nitrogen flow rate is 100ml / min.

[0014] Further, the polymerization reaction conditions are as follows: first, reaction at 180-190℃ for 0.5-1 hour, nitrogen flow rate is 100ml / min; then, reaction at 200-210℃ for 1-2 hours, nitrogen flow rate is 100ml / min; finally, reaction at 240-250℃ for 1-2 hours, nitrogen flow rate is 100ml / min.

[0015] Further, the reaction temperature for removal of ethylene glycol is 260-310℃, the pressure is 100-500Pa, the nitrogen flow rate is 0-80ml / min, and the reaction time is 2-4 hours.

[0016] Further, first, the reaction is carried out at 260-270 DEG C for 0.5-1 hour, the pressure is 500-600 Pa, and the nitrogen flow rate is 80 ml / min; then, the reaction temperature is kept at 260-270 DEG C, the pressure is adjusted to 300-400 Pa, and the nitrogen flow rate is 50 ml / min, and the reaction is carried out for 0.5-1 hour; after the temperature is raised to 280-290 DEG C, the pressure is adjusted to 200-300 Pa, and the nitrogen flow rate is 50 ml / min, and the reaction is carried out for 0.5-1 hour; finally, the temperature is raised to 300-310 DEG C, the pressure is 100 Pa, and the nitrogen flow rate is 0 ml / min, and the reaction is carried out for 0.5-1 hour.

[0017] Further, after the removal of ethylene glycol, the product is discharged at a pressure of 0.1-2 MPa and a temperature of 265-320 DEG C to obtain high intrinsic viscosity polyethylene naphthalate with branched structure.

[0018] The high intrinsic viscosity polyethylene naphthalate with branched structure prepared according to the preparation method has an intrinsic viscosity of 1.1-1.50 dL / g, a yield strength of 66-76 MPa, and a breaking strength of 70-78 MPa.

[0019] Compared with the prior art, the application has the following beneficial effects:

[0020] In the application, the addition of a certain amount of three / tetra-branched monomer, i.e. a three-functional or four-functional monomer, forms a branched chain structure on the polymer main chain, reduces the melt viscosity of the polymer, and is beneficial to the mass transfer and diffusion of the small molecular by-product ethylene glycol, and thus is beneficial to the forward progress of the polycondensation reaction and shortens the reaction time. Meanwhile, the branched structure reduces the viscosity and can remove more by-product ethylene glycol, increases the reaction degree, and obtains a product with higher intrinsic viscosity. The addition amount of the three / tetra-functional monomer directly affects the molecular weight of the PEN resin. When the addition amount is small, the branched chain structure is less, the viscosity reduction effect is small, and the intrinsic viscosity effect is poor. When the addition amount is large, the branched structure increases, and with the increase of the reaction degree, the system is easily crosslinked. Meanwhile, the addition amount of the three / tetra-branched monomer affects the tensile strength of the product. When the addition amount is large, the branched structure in the molecular chain increases, the entanglement effect between the molecular chains is enhanced, and the relative slipping between the molecular chains is limited, thereby improving the tensile strength. When the addition amount is small, the branched structure is less, the entanglement effect between the molecular chains is reduced, and the tensile property is reduced. The functionality of the three / tetra-branched monomer also affects the tensile strength of the resin. The greater the functionality, the higher the polymer chain with higher branched degree is formed, the viscosity reduction effect is more obvious, the entanglement effect between the molecular chains is enhanced, and the high-intrinsic-viscosity PEN resin is more easily obtained. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor.

[0022] Figure 1 The infrared spectrograms of the PEN resin with branched structure synthesized in the present application and the commercially available linear PEN resin;

[0023] Figure 2 The stress-strain curve comparison of the PEN resin with branched structure synthesized in the present application and the commercially available linear PEN resin. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the following will clearly and completely describe the technical solutions in the embodiments of the present application.

[0025] The present application uses dimethyl 2,6-naphthalene dicarboxylate and ethylene glycol as substrates to synthesize by ester exchange reaction. The addition of quantitative trifunctional or tetrafunctional monomers in the substrate formula can form branched chain structure on the polymer main chain, which can reduce the polymer melt viscosity, which is beneficial to the mass transfer and diffusion of the small molecular byproduct ethylene glycol, and further beneficial to the forward progress of the polycondensation reaction, shortening the reaction time. And in the same time, more byproduct ethylene glycol can be removed, so that the reaction degree is increased, and the product intrinsic viscosity is higher. In addition, the branched structure reduces the symmetry of the molecular chain, slows down the crystallization phenomenon in the molding process, and easily obtains products with higher transparency. The PEN polymerization method disclosed in the present application has simple process flow and excellent comprehensive performance of the product, and has broad commercial prospect.

[0026] The high intrinsic viscosity of polyethylene naphthalate in the present application refers to the intrinsic viscosity of 1.0-1.5 dL / g.

[0027] The embodiment of the present application provides a preparation method of high intrinsic viscosity polyethylene naphthalate (PEN) with branched structure, comprising the following steps:

[0028] (1) The following formula is used for feeding: 2,6-naphthalene dicarboxylic acid dimethyl ester 60-65 parts, ethylene glycol 35-40 parts, three / four branched monomers 0.1-2 parts, catalyst 0.01-0.5 parts and antioxidant 0.01-0.5 parts by mass fraction.

[0029] The tri / tetra-branched monomer is one of 1,3,5-benzene tricarboxylic acid trimethyl ester, 1,2,4-benzene tricarboxylic acid trimethyl ester, 1,3,5-benzene tricarboxylic acid triethyl ester, 1,3,6-naphthalene tricarboxylic acid trimethyl ester, benzene-1,2,4,5-tetracarboxylic acid tetramethyl ester, benzene-1,2,4,5-tetracarboxylic acid tetrabutyl ester, and 1,3,5,7-naphthalene tetracarboxylic acid tetramethyl ester, or a mixture of two of them.

[0030] The catalyst is one of zinc acetate and antimony trioxide.

[0031] The antioxidant is one of hindered phenol antioxidant 1010 and triphenyl phosphite, or a mixture of two of them.

[0032] (2) According to the formula of step (1), the air in the reactor is replaced by nitrogen, and this is repeated three times to replace the air in the reactor. The reaction temperature, reaction time and nitrogen flow rate are controlled to remove the small molecular byproduct methanol, specifically: the reaction temperature is 180-250℃, the reaction time is 2.5-5 hours, and the nitrogen flow rate is 80-120ml / min. The specific operation is: the temperature is raised to 180-190℃ for 0.5-1 hour, and the nitrogen flow rate is controlled at 100ml / min; then the temperature is raised to 200-210℃ for 1-2 hours, and the nitrogen flow rate is controlled at 100ml / min; finally the temperature is raised to 240-250℃ for 1-2 hours, and the nitrogen flow rate is controlled at 100ml / min.

[0033] After the removal of methanol, the reaction temperature, pressure, nitrogen flow rate and reaction time are controlled to remove the small molecular byproduct ethylene glycol, specifically: the reaction temperature is 260-310℃, the pressure in the reactor is 100-500Pa, the nitrogen flow rate is 0-80ml / min, and the reaction time is 2-4 hours. The specific operation is: the temperature is raised to 260-270℃ for 0.5-1 hour, the pressure in the reactor is controlled at 500-600Pa by a vacuum pump, and the nitrogen flow rate is 80ml / min; the reaction temperature is maintained at 260-270℃, the pressure in the reactor is controlled at 300-400Pa, and the nitrogen flow rate is 50ml / min, which is reacted for 0.5-1 hour under these conditions; the temperature is raised to 280-290℃, the pressure in the reactor is controlled at 200-300Pa by a vacuum pump, and the nitrogen flow rate is 50ml / min, which is reacted for 0.5-1 hour under these conditions; finally the temperature is raised to 300-310℃, the pressure in the reactor is controlled at 100Pa by a vacuum pump, and the nitrogen flow rate is 0ml / min, which is reacted for 0.5-1 hour under these conditions, and the PEN resin with high intrinsic viscosity is obtained after the removal of ethylene glycol.

[0034] (3) Discharge operation: after the polymerization reaction is completed, the vacuum pump is closed, nitrogen is introduced into the reactor, until the pressure is 0.1-2 Mpa, and the temperature in the reactor is maintained at 265-320℃, the discharge valve is opened, and hot discharge is obtained. Branched high intrinsic viscosity polyethylene naphthalate is obtained.

[0035] The intrinsic viscosity value is determined according to the method shown in the national standard GB / 14190-2017. An appropriate amount of PEN product is taken, a phenol / tetrachloroethane mixture with a mass ratio of 3:2 is used as a solvent, a specific mass concentration of PEN solution is prepared, and the intrinsic viscosity is determined at 25℃ using an Ubbelohde viscometer.

[0036] The tensile strength is tested according to the national standard GB / T 13022.1-2018. An appropriate amount of PEN resin is hot pressed into a film, and cut into dumbbell shape, and its stress-strain performance is tested on a tensile testing machine.

[0037] Example 1

[0038] Step (1): 2,6-naphthalene dicarboxylic acid dimethyl ester 60.75g, ethylene glycol 38.75g, 1,3,5-benzene tricarboxylic acid trimethyl ester 1.2g, zinc acetate 0.05g, triphenyl phosphite 0.1g are taken in the reactor.

[0039] Step (2): The reactor is replaced with nitrogen for 3 times, heated to 180℃ for 1 hour, the nitrogen flow rate is controlled at 100ml / min; heated to 200℃ for 2 hours, the nitrogen flow rate is controlled at 100ml / min; heated to 240℃ for 2 hours, the nitrogen flow rate is controlled at 100ml / min. The small molecule byproduct methanol is collected. The temperature is raised to 260℃, the vacuum pump controls the pressure in the reactor to be 500Pa, the nitrogen flow rate is 80ml / min; the reaction temperature is maintained at 260℃, the pressure in the reactor is controlled to be 300Pa, the nitrogen flow rate is 50ml / min, and the reaction is carried out for 1 hour under this condition; the temperature is raised to 280℃, the vacuum pump controls the pressure in the reactor to be 200Pa, the nitrogen flow rate is 50ml / min, and the reaction is carried out for 1 hour under this condition; the temperature is raised to 300℃, the vacuum pump controls the pressure in the reactor to be 100Pa, the nitrogen flow rate is 0ml / min, and the reaction is carried out for 1 hour under this condition, high intrinsic viscosity PEN resin is obtained. This process is the process of removing the byproduct ethylene glycol.

[0040] Step (3): After the polymerization reaction is completed, the vacuum pump is closed, nitrogen is introduced into the reactor, until the pressure is 1.0 Mpa, and the temperature in the reactor is maintained at 300℃, the discharge valve is opened, and hot discharge is obtained. High viscosity PEN resin is obtained.

[0041] Reference Figure 1 The branched small molecule used is 1,3,5-benzene tricarboxylic acid trimethyl ester, and the amount used is 0.8 parts. Among them, 1709cm-1 at 734 cm-1 is the carbonyl stretching vibration peak, 1175 cm-1 is the out-of-plane bending vibration peak of CH2, 1248 cm-1 is the C-O-C bond stretching vibration peak, and 1610 cm-1 is the C=C stretching vibration peak. -1 at 734 cm-1 is the carbonyl stretching vibration peak, 1175 cm-1 is the out-of-plane bending vibration peak of CH2, 1248 cm-1 is the C-O-C bond stretching vibration peak, and 1610 cm-1 is the C=C stretching vibration peak. -1 at 734 cm-1 is the carbonyl stretching vibration peak, 1175 cm-1 is the out-of-plane bending vibration peak of CH2, 1248 cm-1 is the C-O-C bond stretching vibration peak, and 1610 cm-1 is the C=C stretching vibration peak. -1 at 734 cm-1 is the carbonyl stretching vibration peak, 1175 cm-1 is the out-of-plane bending vibration peak of CH2, 1248 cm-1 is the C-O-C bond stretching vibration peak, and 1610 cm-1 is the C=C stretching vibration peak.

[0042] Referring to Figure 2 It can be seen that the tensile strength of the PEN resin with branched structure synthesized by the application is higher than that of the commercially available resin, and has excellent mechanical properties.

[0043] The intrinsic viscosity value is determined according to the method shown in the national standard GB / 14190-2017. An appropriate amount of PEN product is taken, a phenol / tetrachloroethane mixed solution with a mass ratio of 3:2 is used as a solvent, a PEN solution with a specific mass concentration is prepared, and the intrinsic viscosity is determined at 25°C using an Ubbelohde viscometer.

[0044] The tensile strength is tested according to the national standard GB / T 13022.1-2018. An appropriate amount of PEN resin is hot-pressed into a film, and is cut into a dumbbell shape, and the stress-strain performance is tested on a tensile testing machine.

[0045] The intrinsic viscosity and tensile strength of the resin are shown in the following table:

[0046] Class Intrinsic viscosity Yield strength Breaking strength Unit dL / g MPa MPa Example 1 1.42 72 75

[0047] Example 2

[0048] Step (1): Take 2,6-naphthalene dicarboxylic acid dimethyl ester 60.65 g, ethylene glycol 38.67 g, 1,3,5-benzene tricarboxylic acid trimethyl ester 1.75 g, zinc acetate 0.05 g, and triphenyl phosphite 0.1 g in a reaction kettle.

[0049] Step (2): Replace the air in the reactor with nitrogen for 3 times, and heat to 180℃ for 1 hour, control the nitrogen flow rate to be 100ml / min; heat to 200℃ for 2 hours, control the nitrogen flow rate to be 100ml / min; heat to 240℃ for 2 hours, control the nitrogen flow rate to be 100ml / min. Collect the byproduct methanol in this process. Heat to 260℃ for 1 hour, control the pressure in the reactor to be 500Pa by vacuum pump, and the nitrogen flow rate to be 80ml / min; keep the reaction temperature at 260℃, control the pressure in the reactor to be 300Pa, and the nitrogen flow rate to be 50ml / min; heat to 280℃, control the pressure in the reactor to be 200Pa by vacuum pump, and the nitrogen flow rate to be 50ml / min, react for 1 hour under this condition; heat to 300℃, control the pressure in the reactor to be 100Pa by vacuum pump, and the nitrogen flow rate to be 0ml / min, react for 1 hour under this condition to obtain a high intrinsic viscosity PEN resin. This process is the process of removing the byproduct ethylene glycol.

[0050] Step (3): After the polymerization reaction is completed, close the vacuum pump, introduce nitrogen into the reactor until the pressure is 1.0Mpa, keep the temperature in the reactor at 300℃, open the discharge valve, and hot discharge to obtain a high viscosity PEN resin.

[0051] The intrinsic viscosity value is determined according to the method shown in the national standard GB / 14190-2017. An appropriate amount of PEN product is prepared into a PEN solution with a specific mass concentration by using a phenol / tetrachloroethane mixture with a mass ratio of 3:2 as a solvent, and the intrinsic viscosity is determined at 25℃ using an Ubbelohde viscometer.

[0052] The tensile strength is tested according to the national standard GB / T 13022.1-2018. An appropriate amount of PEN resin is hot pressed into a film, and cut into dumbbell shape, and the stress-strain performance is tested on a tensile testing machine.

[0053] The intrinsic viscosity and tensile strength of the resin are shown in the following table:

[0054] Class Intrinsic viscosity Yield strength Breaking strength Unit dL / g MPa MPa Example 2 1.44 74 75

[0055] Example 3

[0056] Step (1): Take 2,6-naphthalene dimethyl 60.65g, ethylene glycol 38.67g, 1,3,6-naphthalene tricarboxylic acid trimethyl ester 1.8g, zinc acetate 0.05g, and triphenyl phosphite 0.1g in the reactor.

[0057] Step (2): The air in the reactor was replaced with nitrogen for 3 times, and the temperature was raised to 180℃ for 1 hour, the nitrogen flow rate was controlled at 100 ml / min; the temperature was raised to 200℃ for 2 hours, the nitrogen flow rate was controlled at 100 ml / min; the temperature was raised to 240℃ for 2 hours, the nitrogen flow rate was controlled at 100 ml / min. The byproduct methanol was collected during this process. The temperature was raised to 260℃ for 1 hour, the pressure in the reactor was controlled at 500 Pa by a vacuum pump, and the nitrogen flow rate was 80 ml / min; the reaction temperature was maintained at 260℃, the pressure in the reactor was controlled at 300 Pa, and the nitrogen flow rate was 50 ml / min; the temperature was raised to 280℃, the pressure in the reactor was controlled at 200 Pa by a vacuum pump, and the nitrogen flow rate was 50 ml / min, and the reaction was carried out for 1 hour under this condition; the temperature was raised to 300℃, the pressure in the reactor was controlled at 100 Pa by a vacuum pump, and the nitrogen flow rate was 0 ml / min, and the reaction was carried out for 1 hour under this condition to obtain a high intrinsic viscosity PEN resin. This process is a process for removing the byproduct ethylene glycol.

[0058] Step (3): After the completion of the polymerization reaction, the vacuum pump was turned off, nitrogen was introduced into the reactor until the pressure was 1.0 Mpa, the temperature in the reactor was maintained at 300℃, the discharge valve was opened, and hot discharge was carried out to obtain a high viscosity PEN resin.

[0059] The intrinsic viscosity value was determined according to the method shown in the national standard GB / 14190-2017. An appropriate amount of PEN product was prepared into a PEN solution with a specific mass concentration using a phenol / tetrachloroethane mixture with a mass ratio of 3:2 as the solvent, and the intrinsic viscosity was determined at 25℃ using an Ubbelohde viscometer.

[0060] The tensile strength was tested according to the national standard GB / T 13022.1-2018. An appropriate amount of PEN resin was hot pressed into a film, and was cut into dumbbell shapes, and the stress-strain properties were tested on a tensile testing machine.

[0061] The intrinsic viscosity and tensile strength of the resin are shown in the following table:

[0062] Class Intrinsic viscosity Yield strength Breaking strength Unit dL / g MPa MPa Example 3 1.38 71 71

[0063] Example 4

[0064] Step (1): 2,6-naphthalene dicarboxylic acid dimethyl ester 60.83 g, ethylene glycol 38.78 g, 1,2,4,6-benzene tetracarboxylic acid tetramethyl ester 1.2 g, zinc acetate 0.05 g, and triphenyl phosphite 0.1 g were taken in a reaction kettle.

[0065] Step (2): Replace the air in the reactor with nitrogen for 3 times, and heat to 180℃ for 1 hour, control the nitrogen flow rate to be 100ml / min; heat to 200℃ for 2 hours, control the nitrogen flow rate to be 100ml / min; heat to 240℃ for 2 hours, control the nitrogen flow rate to be 100ml / min. Collect the byproduct methanol in this process. Heat to 260℃ for 1 hour, control the pressure in the reactor to be 500Pa by vacuum pump, and the nitrogen flow rate to be 80ml / min; keep the reaction temperature at 260℃, control the pressure in the reactor to be 300Pa, and the nitrogen flow rate to be 50ml / min; heat to 280℃, control the pressure in the reactor to be 200Pa by vacuum pump, and the nitrogen flow rate to be 50ml / min, and react for 1 hour under this condition; heat to 300℃, control the pressure in the reactor to be 100Pa by vacuum pump, and the nitrogen flow rate to be 0ml / min, and react for 1 hour under this condition to obtain a high intrinsic viscosity PEN resin. This process is the process of removing the byproduct ethylene glycol.

[0066] Step (3): After the polymerization reaction is completed, the vacuum pump is closed, nitrogen is introduced into the reactor until the pressure is 1.0Mpa, the temperature in the reactor is kept at 300℃, the discharge valve is opened, and hot discharge is obtained to obtain a high viscosity PEN resin.

[0067] The intrinsic viscosity value is determined according to the method shown in the national standard GB / 14190-2017. An appropriate amount of PEN product is prepared into a PEN solution with a specific mass concentration by using a phenol / tetrachloroethane mixture with a mass ratio of 3:2 as a solvent, and the intrinsic viscosity is determined at 25℃ using an Ubbelohde viscometer.

[0068] The tensile strength is tested according to the national standard GB / T 13022.1-2018. An appropriate amount of PEN resin is hot pressed into a film, and cut into dumbbell shape, and the stress-strain performance is tested on a tensile testing machine.

[0069] The intrinsic viscosity and tensile strength of the resin are shown in the following table:

[0070] Class Intrinsic viscosity Yield strength Breaking strength Unit dL / g MPa MPa Example 4 1.50 75 78

[0071] Example 5

[0072] Step (1): Take 2,6-naphthalene dimethyl 60.84g, ethylene glycol 38.79g, 1,3,5,7-naphthalene tetracarboxylic acid tetramethyl ester 1.4g, zinc acetate 0.05g, and triphenyl phosphite 0.1g in the reactor.

[0073] Step (2): Replace the air in the reactor with nitrogen for 3 times, and heat to 180℃ for 1 hour, control the nitrogen flow rate of 100 ml / min; heat to 200℃ for 2 hours, control the nitrogen flow rate of 100 ml / min; heat to 240℃ for 2 hours, control the nitrogen flow rate of 100 ml / min. Collect the byproduct methanol in this process. Heat to 260℃ for 1 hour, control the pressure in the reactor to be 500 Pa by vacuum pump, and the nitrogen flow rate is 80 ml / min; keep the reaction temperature at 260℃, control the pressure in the reactor to be 300 Pa, and the nitrogen flow rate is 50 ml / min; heat to 280℃, control the pressure in the reactor to be 200 Pa by vacuum pump, and the nitrogen flow rate is 50 ml / min, react for 1 hour under this condition; heat to 300℃, control the pressure in the reactor to be 100 Pa by vacuum pump, and the nitrogen flow rate is 0 ml / min, react for 1 hour under this condition to obtain a high intrinsic viscosity PEN resin. This process is the process of removing the byproduct ethylene glycol.

[0074] Step (3): After the completion of the polymerization reaction, close the vacuum pump, introduce nitrogen into the reactor until the pressure is 1.0 Mpa, keep the temperature in the reactor at 300℃, open the discharge valve, and hot discharge to obtain a high viscosity PEN resin.

[0075] The intrinsic viscosity value is determined according to the method shown in the national standard GB / 14190-2017. An appropriate amount of PEN product is prepared into a PEN solution with a specific mass concentration using a phenol / tetrachloroethane mixture with a mass ratio of 3:2 as a solvent, and the intrinsic viscosity is determined at 25℃ using an Ubbelohde viscometer.

[0076] The tensile strength is tested according to the national standard GB / T 13022.1-2018. An appropriate amount of PEN resin is hot pressed into a film, and cut into dumbbell shape, and the stress-strain performance is tested on a tensile testing machine.

[0077] The intrinsic viscosity and tensile strength of the resin are shown in the following table:

[0078] Class Intrinsic viscosity Yield strength Breaking Unit dL / g MPa MPa Example 5 1.46 74 77

[0079] Example 6

[0080] Step (1): Take 2,6-naphthalene dimethyl 60.77 g, ethylene glycol 38.75 g, 1,2,4,6-benzene tetracarboxylic acid tetramethyl ester 0.8 g, 1,3,5,7-naphthalene tetracarboxylic acid tetramethyl ester 0.18 g, zinc acetate 0.05 g, and triphenyl phosphite 0.1 g in the reactor.

[0081] Step (2): Replace the air in the reactor with nitrogen for 3 times, and heat to 180℃ for 1 hour, control the nitrogen flow rate to be 100 ml / min; heat to 200℃ for 2 hours, control the nitrogen flow rate to be 100 ml / min; heat to 240℃ for 2 hours, control the nitrogen flow rate to be 100 ml / min. Collect the byproduct methanol in this process. Heat to 260℃ for 1 hour, control the pressure in the reactor to be 500 Pa by vacuum pump, and the nitrogen flow rate to be 80 ml / min; keep the reaction temperature at 260℃, control the pressure in the reactor to be 300 Pa, and the nitrogen flow rate to be 50 ml / min; heat to 280℃, control the pressure in the reactor to be 200 Pa by vacuum pump, and the nitrogen flow rate to be 50 ml / min, react for 1 hour under this condition; heat to 300℃, control the pressure in the reactor to be 100 Pa by vacuum pump, and the nitrogen flow rate to be 0 ml / min, react for 1 hour under this condition to obtain a high intrinsic viscosity PEN resin. This process is the process of removing the byproduct ethylene glycol.

[0082] Step (3): After the completion of the polymerization reaction, close the vacuum pump, introduce nitrogen into the reactor until the pressure is 1.0 Mpa, keep the temperature in the reactor at 300℃, open the discharge valve, and hot discharge to obtain a high viscosity PEN resin.

[0083] The intrinsic viscosity value is determined according to the method shown in the national standard GB / 14190-2017. An appropriate amount of PEN product is prepared into a PEN solution with a specific mass concentration using a phenol / tetrachloroethane mixture with a mass ratio of 3:2 as the solvent, and the intrinsic viscosity is determined at 25℃ using an Ubbelohde viscometer.

[0084] The tensile strength is tested according to the national standard GB / T 13022.1-2018. An appropriate amount of PEN resin is hot pressed into a film, and cut into dumbbell shape, and the stress-strain performance is tested on a tensile testing machine.

[0085] The intrinsic viscosity and tensile strength of the resin are shown in the following table:

[0086] Class Intrinsic viscosity Yield strength Tensile strength Unit dL / g MPa MPa Example 5 1.26 66 70

[0087] Example 7

[0088] Step (1): Take 2,6-naphthalene dicarboxylic acid dimethyl ester 60.65 g, ethylene glycol 38.67 g, 1,3,6-naphthalene tricarboxylic acid trimethyl ester 1.8 g, zinc acetate 0.05 g, and triphenyl phosphite 0.1 g in the reactor.

[0089] Step (2): Replace the air in the reactor with nitrogen for 3 times, and heat to 180℃ for 0.5 hours, control the nitrogen flow rate at 100 ml / min; heat to 200℃ for 1.5 hours, control the nitrogen flow rate at 100 ml / min; heat to 240℃ for 1.5 hours, control the nitrogen flow rate at 100 ml / min. Collect the byproduct methanol in this process. Heat to 260℃ for 0.5 hours, control the pressure in the reactor to be 500 Pa by vacuum pump, and the nitrogen flow rate is 80 ml / min; keep the reaction temperature at 260℃, control the pressure in the reactor to be 300 Pa, and the nitrogen flow rate is 50 ml / min; heat to 280℃, control the pressure in the reactor to be 200 Pa by vacuum pump, and the nitrogen flow rate is 50 ml / min, react for 0.5 hours under this condition; heat to 300℃, control the pressure in the reactor to be 100 Pa by vacuum pump, and the nitrogen flow rate is 0 ml / min, react for 0.5 hours under this condition to obtain a high intrinsic viscosity PEN resin. This process is to remove the byproduct ethylene glycol.

[0090] Step (3): After the polymerization reaction is completed, close the vacuum pump, introduce nitrogen into the reactor until the pressure is 1.0 Mpa, keep the temperature in the reactor at 300℃, open the discharge valve, and hot discharge to obtain a high viscosity PEN resin.

[0091] The intrinsic viscosity value is determined according to the method shown in the national standard GB / 14190-2017. An appropriate amount of PEN product is prepared into a PEN solution with a specific mass concentration by using a phenol / tetrachloroethane mixture with a mass ratio of 3:2 as a solvent, and the intrinsic viscosity is determined at 25℃ using an Ubbelohde viscometer.

[0092] The tensile strength is tested according to the national standard GB / T 13022.1-2018. An appropriate amount of PEN resin is hot pressed into a film, and cut into dumbbell shape, and the stress-strain performance is tested on a tensile testing machine.

[0093] The intrinsic viscosity and tensile strength of the resin are shown in the following table:

[0094] Class Intrinsic viscosity Yield strength Breaking strength Unit dL / g MPa MPa Example 7 1.28 67 70

[0095] Example 8

[0096] Step (1): Take 2,6-naphthalene dimethyl 60.84 g, ethylene glycol 38.79 g, 1,3,5,7-naphthalene tetracarboxylic acid tetramethyl ester 1.4 g, zinc acetate 0.05 g, and triphenyl phosphite 0.1 g in the reactor.

[0097] Step (2): Replace the air in the reactor with nitrogen for 3 times, and heat to 180℃ for 0.5 hours, control the nitrogen flow rate at 100ml / min; heat to 200℃ for 1.5 hours, control the nitrogen flow rate at 100ml / min; heat to 240℃ for 1.5 hours, control the nitrogen flow rate at 100ml / min. Collect the byproduct methanol in this process. Heat to 260℃ for 1 hour, control the pressure in the reactor to 500Pa by vacuum pump, and the nitrogen flow rate is 80ml / min; keep the reaction temperature at 260℃, control the pressure in the reactor to 300Pa, and the nitrogen flow rate is 50ml / min; heat to 280℃, control the pressure in the reactor to 200Pa by vacuum pump, and the nitrogen flow rate is 50ml / min, react for 0.5 hours under this condition; heat to 300℃, control the pressure in the reactor to 100Pa by vacuum pump, and the nitrogen flow rate is 0ml / min, react for 0.5 hours under this condition to obtain a high intrinsic viscosity PEN resin. This process is to remove the byproduct ethylene glycol.

[0098] Step (3): After the completion of the polymerization reaction, close the vacuum pump, introduce nitrogen into the reactor until the pressure is 1.0Mpa, keep the temperature in the reactor at 300℃, open the discharge valve, and hot discharge to obtain a high viscosity PEN resin.

[0099] The intrinsic viscosity value is determined according to the method shown in the national standard GB / 14190-2017. Take an appropriate amount of PEN product, use a phenol / tetrachloroethane mixture with a mass ratio of 3:2 as the solvent, prepare a PEN solution with a specific mass concentration, and use an Ubbelohde viscometer to determine the intrinsic viscosity at 25℃.

[0100] The tensile strength is tested according to the national standard GB / T 13022.1-2018. Take an appropriate amount of PEN resin, hot press it into a film, and cut it into dumbbell shape, and test its stress-strain performance on a tensile testing machine.

[0101] The intrinsic viscosity and tensile strength of the resin are shown in the following table:

[0102] Class Intrinsic viscosity Yield strength Breaking Unit dL / g MPa MPa Example 8 1.44 73 76

[0103] Example 9

[0104] Step (1): Take 2,6-naphthalene dicarboxylic acid dimethyl ester 60g, ethylene glycol 35g, 1,3,5-benzene tricarboxylic acid trimethyl ester 0.1g, 1,3,5,7-naphthalene tetracarboxylic acid tetramethyl ester 0.1g, antimony trioxide 0.01g, triphenyl phosphite 0.01g in the reactor.

[0105] Step (2): The air in the reactor was replaced with nitrogen for 3 times, and the temperature was raised to 190°C for 0.5 hours, the nitrogen flow rate was controlled at 100 ml / min; the temperature was raised to 200°C for 2 hours, the nitrogen flow rate was controlled at 100 ml / min; the temperature was raised to 240°C for 2 hours, the nitrogen flow rate was controlled at 100 ml / min. The small molecule byproduct methanol was collected in this process. The temperature was raised to 260°C for 1 hour, the pressure in the reactor was controlled at 500 Pa by a vacuum pump, and the nitrogen flow rate was 80 ml / min; the reaction temperature was maintained at 260°C, the pressure in the reactor was controlled at 300 Pa, and the nitrogen flow rate was 50 ml / min, which was reacted for 1 hour under this condition; the temperature was raised to 280°C, the pressure in the reactor was controlled at 200 Pa by a vacuum pump, and the nitrogen flow rate was 50 ml / min, which was reacted for 0.5 hours under this condition; the temperature was raised to 310°C, the pressure in the reactor was controlled at 100 Pa by a vacuum pump, and the nitrogen flow rate was 0 ml / min, which was reacted for 1 hour under this condition, and a high intrinsic viscosity PEN resin was obtained. This process is the process of removing the byproduct ethylene glycol.

[0106] Step (3): After the polymerization reaction was completed, the vacuum pump was closed, nitrogen was introduced into the reactor until the pressure was 0.5 MPa, the temperature in the reactor was maintained at 265°C, the discharge valve was opened, and hot discharge was obtained, thereby obtaining a high viscosity PEN resin.

[0107] Example 10

[0108] Step (1): 65 g of dimethyl 2,6-naphthalene dicarboxylate, 36 g of ethylene glycol, 0.3 g of trimethyl 1,3,5-benzene tricarboxylate, 0.2 g of tetrabutyl benzene-1,2,4,5-tetracarboxylate, 0.5 g of antimony trioxide, and 0.2 g of hindered phenolic antioxidant 1010 were prepared in a reactor.

[0109] Step (2): The air in the reactor was replaced with nitrogen for 3 times, and the temperature was raised to 180°C for 1 hour, the nitrogen flow rate was controlled at 100 ml / min; the temperature was raised to 210°C for 1 hour, the nitrogen flow rate was controlled at 100 ml / min; the temperature was raised to 250°C for 1 hour, the nitrogen flow rate was controlled at 100 ml / min. The small molecule byproduct methanol was collected in this process. The temperature was raised to 270°C for 0.5 hours, the pressure in the reactor was controlled at 500 Pa by a vacuum pump, and the nitrogen flow rate was 80 ml / min; the reaction temperature was maintained at 270°C, the pressure in the reactor was controlled at 400 Pa, and the nitrogen flow rate was 50 ml / min, which was reacted for 0.5 hours under this condition; the temperature was raised to 290°C, the pressure in the reactor was controlled at 200 Pa by a vacuum pump, and the nitrogen flow rate was 50 ml / min, which was reacted for 1 hour under this condition; the temperature was raised to 305°C, the pressure in the reactor was controlled at 100 Pa by a vacuum pump, and the nitrogen flow rate was 0 ml / min, which was reacted for 1 hour under this condition, and a high intrinsic viscosity PEN resin was obtained. This process is the process of removing the byproduct ethylene glycol.

[0110] Step (3): After the polymerization reaction is completed, the vacuum pump is closed, nitrogen is introduced into the reactor until the pressure is 1.0 MPa, the temperature in the reactor is kept at 320°C, the discharge valve is opened, and hot discharge is performed to obtain a high-viscosity PEN resin.

[0111] Example 11

[0112] Step (1): 2,6-naphthalene dicarboxylic acid dimethyl ester 62 g, ethylene glycol 37 g, 1,3,5-benzene tricarboxylic acid trimethyl ester 1 g, zinc acetate 0.2 g, and triphenyl phosphite 0.3 g are placed in a reactor.

[0113] Step (2): The air in the reactor is replaced with nitrogen for 3 times, the temperature is raised to 185°C, and the reaction is performed for 0.8 hours with the nitrogen flow rate controlled at 100 ml / min; the temperature is raised to 205°C, and the reaction is performed for 1.5 hours with the nitrogen flow rate controlled at 100 ml / min; the temperature is raised to 243°C, and the reaction is performed for 1.5 hours with the nitrogen flow rate controlled at 100 ml / min. In this process, methanol, a small molecule by-product, is collected. The temperature is raised to 265°C, the vacuum pump is controlled to have the pressure in the reactor at 500 Pa, and the nitrogen flow rate is controlled at 80 ml / min; the reaction temperature is kept at 263°C, the pressure in the reactor is controlled at 350 Pa, and the nitrogen flow rate is controlled at 50 ml / min, and the reaction is performed for 0.8 hours under this condition; the temperature is raised to 282°C, the vacuum pump is controlled to have the pressure in the reactor at 200 Pa, and the nitrogen flow rate is controlled at 50 ml / min, and the reaction is performed for 0.8 hours under this condition; the temperature is raised to 300°C, the vacuum pump is controlled to have the pressure in the reactor at 100 Pa, and the nitrogen flow rate is controlled at 0 ml / min, and the reaction is performed for 0.7 hours under this condition to obtain a high-viscosity PEN resin. In this process, ethylene glycol, a by-product, is removed.

[0114] Step (3): After the polymerization reaction is completed, the vacuum pump is closed, nitrogen is introduced into the reactor until the pressure is 2.0 MPa, the temperature in the reactor is kept at 280°C, the discharge valve is opened, and hot discharge is performed to obtain a high-viscosity PEN resin.

[0115] Example 12

[0116] Step (1): 2,6-naphthalene dicarboxylic acid dimethyl ester 63 g, ethylene glycol 40 g, 1,3,5-benzene tricarboxylic acid triethyl ester 1 g, benzene-1,2,4,5-tetracarboxylic acid tetramethyl ester 1 g, zinc acetate 0.3 g, hindered phenolic antioxidant 1010 0.2 g, and triphenyl phosphite 0.3 g are placed in a reactor.

[0117] Step (2): The air in the reactor was replaced with nitrogen for 3 times, and the temperature was raised to 187°C for 1 hour, the nitrogen flow rate was controlled at 100 ml / min; the temperature was raised to 207°C for 1.5 hours, the nitrogen flow rate was controlled at 100 ml / min; the temperature was raised to 248°C for 1.5 hours, the nitrogen flow rate was controlled at 100 ml / min. In this process, methanol, a small molecule by-product, was collected. The temperature was raised to 268°C for 0.6 hours, the pressure in the reactor was controlled at 500 Pa by a vacuum pump, and the nitrogen flow rate was 80 ml / min; the reaction temperature was maintained at 266°C, the pressure in the reactor was controlled at 380 Pa, and the nitrogen flow rate was 50 ml / min, which was reacted for 0.6 hours; the temperature was raised to 287°C, the pressure in the reactor was controlled at 200 Pa by a vacuum pump, and the nitrogen flow rate was 50 ml / min, which was reacted for 0.6 hours; the temperature was raised to 300°C, the pressure in the reactor was controlled at 100 Pa by a vacuum pump, and the nitrogen flow rate was 0 ml / min, which was reacted for 0.8 hours, and a high intrinsic viscosity PEN resin was obtained. This process is a process for removing the by-product ethylene glycol.

[0118] Step (3): After the polymerization reaction was completed, the vacuum pump was closed, nitrogen was introduced into the reactor until the pressure was 0.10 Mpa, and the temperature in the reactor was maintained at 310°C, the discharge valve was opened, and hot discharge was obtained. A high viscosity PEN resin was obtained.

[0119] The reaction time of the high intrinsic viscosity polyethylene naphthalate with branched structure prepared by the application is 7-9 hours, the intrinsic viscosity is 1.26-1.50 dL / g, the yield strength is 66-76 Mpa, and the breaking strength is 70-78 Mpa.

[0120] Comparative Example 1

[0121] Step (1): 2,6-naphthalene dicarboxylic acid dimethyl ester 61.06 g, ethylene glycol 38.94 g, zinc acetate 0.05 g, and triphenyl phosphite 0.1 g were prepared in a reactor.

[0122] Step (2): The air in the reactor was replaced with nitrogen for 3 times, and the temperature was raised to 180℃ for 1 hour, the nitrogen flow rate was controlled at 100 ml / min; the temperature was raised to 200℃ for 2 hours, the nitrogen flow rate was controlled at 100 ml / min; the temperature was raised to 240℃ for 2 hours, the nitrogen flow rate was controlled at 100 ml / min. The small molecule byproduct methanol was collected. The temperature was raised to 260℃ for 1 hour, the pressure in the reactor was controlled at 500 Pa by a vacuum pump, and the nitrogen flow rate was 80 ml / min; the reaction temperature was maintained at 260℃, the pressure in the reactor was controlled at 300 Pa, and the nitrogen flow rate was 50 ml / min; the temperature was raised to 280℃, the pressure in the reactor was controlled at 200 Pa by a vacuum pump, and the nitrogen flow rate was 50 ml / min, the reaction was carried out for 1 hour under this condition; the temperature was raised to 300℃, the pressure in the reactor was controlled at 100 Pa by a vacuum pump, and the nitrogen flow rate was 0 ml / min, the reaction was carried out for 1 hour under this condition to obtain a high intrinsic viscosity PEN resin. This process is a process for removing the byproduct ethylene glycol.

[0123] Step (3): After the completion of the polymerization reaction, the vacuum pump was turned off, nitrogen was introduced into the reactor until the pressure was 1.0 Mpa, and the temperature in the reactor was maintained at 300℃, the discharge valve was opened, and hot discharge was carried out to obtain a high viscosity PEN resin.

[0124] The intrinsic viscosity value was determined according to the method shown in the national standard GB / 14190-2017. An appropriate amount of PEN product was prepared into a PEN solution with a specific mass concentration using a phenol / tetrachloroethane mixture with a mass ratio of 3:2 as the solvent, and the intrinsic viscosity was determined at 25℃ using an Ubbelohde viscometer.

[0125] The tensile strength was tested according to the national standard GB / T 13022.1-2018. An appropriate amount of PEN resin was hot pressed into a film, and was cut into dumbbell shape, and the stress-strain performance was tested on a tensile testing machine.

[0126] The intrinsic viscosity and tensile strength of the resin are shown in the following table:

[0127] Class Intrinsic viscosity Yield strength Breaking strength Unit dL / g MPa MPa Comparative Example 1 0.45 34 45

[0128] Comparative Example 2

[0129] Step (1): 2,6-naphthalene dicarboxylic acid dimethyl ester 61.06 g, 1,2,4,6-benzene tetracarboxylic acid tetramethyl ester 0.05 g, ethylene glycol 38.94 g, zinc acetate 0.05 g, and triphenyl phosphite 0.1 g were taken in a reaction kettle.

[0130] Step (2): The air in the reactor was replaced with nitrogen for 3 times, and the temperature was raised to 180℃ for 1 hour, the nitrogen flow rate was controlled at 100 ml / min; the temperature was raised to 200℃ for 2 hours, the nitrogen flow rate was controlled at 100 ml / min; the temperature was raised to 240℃ for 2 hours, the nitrogen flow rate was controlled at 100 ml / min. The byproduct methanol was collected during this process. The temperature was raised to 260℃ for 1 hour, the pressure in the reactor was controlled at 500 Pa by a vacuum pump, and the nitrogen flow rate was 80 ml / min; the reaction temperature was maintained at 260℃, the pressure in the reactor was controlled at 300 Pa, and the nitrogen flow rate was 50 ml / min; the temperature was raised to 280℃, the pressure in the reactor was controlled at 200 Pa by a vacuum pump, and the nitrogen flow rate was 50 ml / min, and the reaction was carried out for 1 hour under this condition; the temperature was raised to 300℃, the pressure in the reactor was controlled at 100 Pa by a vacuum pump, and the nitrogen flow rate was 0 ml / min, and the reaction was carried out for 1 hour under this condition to obtain a high intrinsic viscosity PEN resin. This process is a process for removing the byproduct ethylene glycol.

[0131] Step (3): After the completion of the polymerization reaction, the vacuum pump was turned off, nitrogen was introduced into the reactor until the pressure was 1.0 Mpa, the temperature in the reactor was maintained at 300℃, the discharge valve was opened, and hot discharge was carried out to obtain a high viscosity PEN resin.

[0132] The intrinsic viscosity value was determined according to the method shown in the national standard GB / 14190-2017. An appropriate amount of PEN product was prepared into a PEN solution with a specific mass concentration using a phenol / tetrachloroethane mixture with a mass ratio of 3:2 as the solvent, and the intrinsic viscosity was determined at 25℃ using an Ubbelohde viscometer.

[0133] The tensile strength was tested according to the national standard GB / T 13022.1-2018. An appropriate amount of PEN resin was hot pressed into a film, and was cut into dumbbell shapes, and the stress-strain properties were tested on a tensile testing machine.

[0134] The intrinsic viscosity and tensile strength of the resin are shown in the following table:

[0135] Class Intrinsic viscosity Yield strength Breaking strength Unit dL / g MPa MPa Comparative Example 2 0.46 34 47

[0136] Comparative Example 3

[0137] Step (1): 2,6-naphthalene dicarboxylic acid dimethyl ester 61.06 g, 1,3,5-benzene tricarboxylic acid trimethyl ester 5.0 g, ethylene glycol 38.94 g, zinc acetate 0.05 g, and triphenyl phosphite 0.1 g were placed in a reaction kettle.

[0138] Step (2): The air in the reactor was replaced with nitrogen for 3 times, and the temperature was raised to 180°C for 1 hour with the nitrogen flow rate of 100 ml / min; the temperature was raised to 200°C for 2 hours with the nitrogen flow rate of 100 ml / min; the temperature was raised to 240°C for 2 hours with the nitrogen flow rate of 100 ml / min. The small molecule by-product methanol was collected. The temperature was raised to 260°C for 1 hour with the vacuum pump controlling the pressure in the reactor to be 500 Pa and the nitrogen flow rate to be 80 ml / min; the temperature was kept at 260°C with the pressure in the reactor being controlled to be 300 Pa and the nitrogen flow rate being 50 ml / min; the temperature was raised to 280°C with the vacuum pump controlling the pressure in the reactor to be 200 Pa and the nitrogen flow rate to be 50 ml / min, and the reaction was carried out for 1 hour under the above conditions; the temperature was raised to 300°C with the vacuum pump controlling the pressure in the reactor to be 100 Pa and the nitrogen flow rate to be 0 ml / min, and the reaction was carried out for 1 hour under the above conditions to obtain a high intrinsic viscosity PEN resin. This process is a process for removing the by-product ethylene glycol.

[0139] Step (3): After the completion of the polymerization reaction, the vacuum pump was turned off, nitrogen was introduced into the reactor until the pressure was 1.0 MPa, and the temperature in the reactor was kept at 300°C. The discharge valve was opened, and it was found that the material was gelled and caked in the reactor, and the resin could not be obtained.

[0140] Comparative Example 4

[0141] Step (1): 2,6-naphthalene dicarboxylic acid dimethyl ester 61.06 g, 1,2,4,6-benzene tetracarboxylic acid tetramethyl ester 5.0 g, ethylene glycol 38.94 g, zinc acetate 0.05 g, and triphenyl phosphite 0.1 g were taken in a reactor.

[0142] Step (2): The air in the reactor was replaced with nitrogen for 3 times, and the temperature was raised to 180°C for 1 hour with the nitrogen flow rate of 100 ml / min; the temperature was raised to 200°C for 2 hours with the nitrogen flow rate of 100 ml / min; the temperature was raised to 240°C for 2 hours with the nitrogen flow rate of 100 ml / min. The small molecule by-product methanol was collected. The temperature was raised to 260°C for 1 hour with the vacuum pump controlling the pressure in the reactor to be 500 Pa and the nitrogen flow rate to be 80 ml / min; the temperature was kept at 260°C with the pressure in the reactor being controlled to be 300 Pa and the nitrogen flow rate being 50 ml / min; the temperature was raised to 280°C with the vacuum pump controlling the pressure in the reactor to be 200 Pa and the nitrogen flow rate to be 50 ml / min, and the reaction was carried out for 1 hour under the above conditions; the temperature was raised to 300°C with the vacuum pump controlling the pressure in the reactor to be 100 Pa and the nitrogen flow rate to be 0 ml / min, and the reaction was carried out for 1 hour under the above conditions to obtain a high intrinsic viscosity PEN resin. This process is a process for removing the by-product ethylene glycol.

[0143] Step (3): After the polymerization reaction, the vacuum pump was closed, nitrogen was introduced into the reactor until the pressure was 1.0 Mpa, and the temperature in the reactor was kept at 300℃. The discharge valve was opened, and the material was found to be gelled and clumped in the reactor, and the resin could not be obtained.

[0144] From the comparison of Comparative Examples 1-4 and Examples 1-8, it can be seen that, in Comparative Example 1, no branched monomer was added, and the viscosity was small; in Comparative Example 2, the amount of branched monomer was small, and the effect was poor; in Comparative Examples 3 and 4, excessive branched monomer was added, and the system was gelled; the addition of trifunctional monomer and tetrafunctional monomer can effectively increase the intrinsic viscosity of the PEN resin, and the yield strength and breaking strength are also improved. However, too much addition will lead to gelation of the system; too little addition will have poor effect.

[0145] The above is only a preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A process for producing a high intrinsic viscosity polyethylene naphthalate having a branched structure, characterized by, It comprises the following steps: The 2,6-naphthalene dimethyl acid dimethyl ester 60-65 parts, ethylene glycol 35-40 parts, three / four branched monomer 0.1-2 parts, catalyst 0.01-0.5 parts and antioxidant 0.01-0.5 parts are polymerized and methanol is removed, then ethylene glycol is removed, so as to obtain the high intrinsic viscosity polyethylene glycol naphthalate with branched structure; the intrinsic viscosity of the polyethylene glycol naphthalate is 1.1-1.50 dL / g, the yield strength is 66-76 Mpa, and the breaking strength is 70-78 MPa. The three / four branched monomer is one of 1,3,5-benzene tricarboxylic acid trimethyl ester, 1,2,4-benzene tricarboxylic acid trimethyl ester, 1,3,5-benzene tricarboxylic acid triethyl ester, 1,3,6-naphthalene tricarboxylic acid trimethyl ester, benzene-1,2,4,5-tetracarboxylic acid tetramethyl ester, 1,2,4,5-benzene tetracarboxylic acid tetrabutyl ester and 1,3,5,7-naphthalene tetracarboxylic acid tetramethyl ester or a mixture of two thereof. The catalyst is one of zinc acetate and antimony trioxide.

2. The method of producing high intrinsic viscosity polyethylene naphthalate having a branched structure according to claim 1, characterized by, The antioxidant is one of hindered phenol antioxidant 1010 and triphenyl phosphite or a mixture of two thereof.

3. The method of producing high intrinsic viscosity polyethylene naphthalate having a branched structure according to claim 1, characterized by, The polymerization reaction condition is that the reaction temperature is 180-250 DEG C, the time is 2.5-5 hours, and the nitrogen flow rate is 100 ml / min.

4. The method of producing high intrinsic viscosity polyethylene naphthalate having a branched structure according to claim 3, characterized by, The polymerization reaction condition is that firstly, the reaction is carried out at 180-190 DEG C for 0.5-1 hour, the nitrogen flow rate is 100 ml / min; then, the temperature is raised to 200-210 DEG C, the reaction is carried out for 1-2 hours, and the nitrogen flow rate is 100 ml / min; finally, the temperature is raised to 240-250 DEG C, the reaction is carried out for 1-2 hours, and the nitrogen flow rate is 100 ml / min.

5. The method of producing high intrinsic viscosity polyethylene naphthalate having a branched structure according to claim 1, characterized by, The reaction temperature for removing ethylene glycol is 260-310 DEG C, the pressure is 100-500 Pa, the nitrogen flow rate is 0-80 ml / min, and the reaction time is 2-4 hours.

6. The method of producing high inherent viscosity polyethylene naphthalate with branched structure according to claim 5, characterized in that, Firstly, the reaction is carried out at 260-270 DEG C for 0.5-1 hour, the pressure is 500-600 Pa, and the nitrogen flow rate is 80 ml / min; then, the reaction temperature is kept at 260-270 DEG C, the pressure is adjusted to 300-400 Pa, and the nitrogen flow rate is 50 ml / min, and the reaction is carried out for 0.5-1 hour under the above condition; after the temperature is raised to 280-290 DEG C, the pressure is adjusted to 200-300 Pa, the nitrogen flow rate is 50 ml / min, and the reaction is carried out for 0.5-1 hour; finally, the temperature is raised to 300-310 DEG C, the pressure is 100 Pa, the nitrogen flow rate is 0 ml / min, and the reaction is carried out for 0.5-1 hour.

7. The method of producing high inherent viscosity polyethylene naphthalate with branched structure according to claim 1, characterized by, After removing ethylene glycol, the high intrinsic viscosity polyethylene glycol naphthalate with branched structure is obtained by discharging at the pressure of 0.1-2 Mpa and the temperature of 265-320 DEG C.

8. The high intrinsic viscosity polyethylene naphthalate having a branched structure, prepared by the preparation method according to claim 1, characterized in that, The intrinsic viscosity of the polyethylene glycol naphthalate is 1.1-1.50 dL / g, the yield strength is 66-76 Mpa, and the breaking strength is 70-78 MPa.

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