Method for producing high-viscosity decorative base film by using super bright PET (Polyethylene Terephthalate)

Abstract

The invention discloses a method for producing a high-viscosity decorative base film by using super bright PET (Polyethylene Terephthalate). The method comprises the following steps: 1) preparing raw materials and auxiliary materials; 2) esterification I; 3) esterification II; 4) polycondensation I; 5) polycondensation II; 6) post-polycondensation; and 7) dicing and packaging. (8) tackifying; (9) drawing the film; and 10) packaging the membrane material. According to the method for producing the high-viscosity decorative base film by using the super bright PET, ethylene glycol circulation, evaporation and replenishing are facilitated; the esterification efficiency of the PTA polymer is improved; and the viscosity of the PTA polymer is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of PAT polyester, and in particular relates to a method for producing a high-viscosity decorative base film by utilizing high-gloss PET. Background Art

[0002] In recent years, my country's PTA polyester technology has made great progress. The existing traditional polyester process has high cost, complicated process route and high raw material loss ratio. The synthesis process of polyester mainly involves using dibasic acid and ethylene glycol as raw materials, and finally forming polyester products through a series of chemical reactions such as esterification, pre-condensation and final polycondensation. The synthesis process of polyester includes not only the preparation of raw materials and the control of reaction conditions, but also the post-processing of products, such as heat setting and stretching, to improve the quality and performance of products. These process technologies have a wide range of applications, including but not limited to the synthesis of heat shrinkable film polyester, and the production of polyester fibers, sheets and films, which are widely used in industry and agriculture, new technology fields, packaging industry, electronic appliances, medical and health, construction, automobiles and other fields. With a wide range of applications, it has attracted more and more attention.

[0003] In the prior art, the direct esterification polyester synthesis reaction principle is: PTA, IPA and ethylene glycol are used as the main raw materials to synthesize PET, and the reaction process mainly includes esterification reaction and polycondensation reaction. In addition, it is also accompanied by some side reactions to a certain extent.

[0004] (1) Esterification reaction:

[0005] Direct esterification and dehydration of PTA (purified terephthalic acid) IPA (isophthalic acid) and ethylene glycol (ethylene glycol) produces the monomer (BHET) bis(hydroxyethyl) terephthalate, in addition to a small molecule product - water.

[0006] This reaction is a reversible reaction. The slurry needs to be quickly raised from room temperature to the reaction temperature, so a large amount of heat needs to be absorbed. Its chemical equilibrium constant is relatively small, and the water produced by the reaction must be continuously removed to allow the esterification reaction to continue in the positive direction. Therefore, in the esterification reaction section, a process tower for separating and removing water is provided.

[0007] (2) Polycondensation reaction:

[0008] The polycondensation reaction is a chain growth reaction in the polyester synthesis process. Through this reaction, two ethylene glycol ester groups undergo polycondensation and remove one molecule of ethylene glycol.

[0009] In this way, monomer (BHET) and monomer, monomer and oligomer, oligomer and oligomer will gradually condense to form high molecular weight polyester.

[0010] The polycondensation reaction is also a reversible equilibrium reaction, and its reaction equilibrium constant is small. Therefore, during the reaction, the ethylene glycol generated by the reaction must be removed as much as possible, otherwise high molecular weight polyester will not be obtained. For this reason, the polycondensation reaction requires to be carried out under vacuum conditions, and a certain amount of catalyst must be added to accelerate the reaction rate. At the same time, the evaporation surface of the reactants should be increased as much as possible to facilitate the evaporation of ethylene glycol in the system. The melt viscosity is controlled at 0.65dl / g±0.02

[0011] (3) Pellet conveying

[0012] The polymer passes through the melt discharge pump under vacuum conditions, part of the material passes through the melt filter and is then pelletized and packaged, and part of the material is transported to the solid phase viscosity increasing system for viscosity increasing.

[0013] (4) Solid phase polymerization

[0014] Process system description

[0015] Solid phase polycondensation (SSP) refers to the intermolecular polycondensation reaction of small molecular chain organic polymer compounds in a solid state and under the protection of inert gas, which increases the degree of polymerization and molecular weight and improves the physical and chemical properties of organic compounds. When polyester undergoes polymerization reaction, compared with liquid phase polycondensation, solid phase polycondensation increases molecular weight at a lower temperature, increases inherent viscosity, inhibits the occurrence of various side reactions, and ensures the minimum thermal cracking variable. It can effectively remove useless and harmful by-products, such as oligomers such as ethylene glycol.

[0016] Condensation reaction mechanism:

[0017]

[0018] Esterification reaction mechanism:

[0019]

[0020] Based on the above, the material used for domestic decorative base film is APET, and its production process and flow are complicated, and it needs to go through underwater pelletizing, transportation, and solid phase viscosity enhancement device system, which has high investment cost and high energy consumption. It is very necessary to invent a production system and process of PTA material to replace APET material. Summary of the invention

[0021] The technical problem to be solved by the present invention is to provide a PTA polyester system and process, which solves the problems in the prior art of low viscosity of PTA polymer, low esterification efficiency, small evaporation area of ​​ethylene glycol, inability to replenish fresh ethylene glycol required in the reaction system, and inability of excess ethylene glycol to overflow into a recycled ethylene glycol tank for slurry configuration.

[0022] In order to solve the above technical problems, the solution of the present invention is: a method for producing a high-viscosity decorative base film using bright PET, comprising the following steps:

[0023] 1) Preparation of raw and auxiliary materials

[0024] The ethylene glycol in the recycled ethylene glycol receiving tank is measured by the meter and then quantitatively enters the slurry preparation tank. After the fresh ethylene glycol and the catalyst ethylene glycol solution are placed in the slurry preparation tank, PTA is evenly placed in the slurry preparation tank with a ton bag of PTA as the measurement under stirring to make slurry; the slurry in the slurry intermediate tank is pumped by a screw pump, then passed through a mass flow meter and a three-way valve to enter the esterification I reactor. The density meter can monitor the slurry molar ratio, and the slurry can also be circulated back to the slurry intermediate tank through the three-way valve; the liquid level control output of the esterification I system is converted and used as the set value of the mass flow meter to control the speed of the screw pump; catalyst preparation, in the catalyst preparation First, add a specified amount of fresh ethylene glycol to the preparation tank through a flow meter, start the agitator, and heat up at the same time, control the temperature at 110°C, keep it warm for 0.5h, add a specified amount of catalyst ethylene glycol antimony, heat and continue stirring for 2h, and after dissolving at the specified temperature, prepare a solution with a concentration of 2.0% (wt) in the catalyst preparation tank. After the prepared catalyst ethylene glycol solution in the catalyst preparation tank is analyzed and the concentration is qualified, it is filtered through a filter and then transferred to the catalyst finished product tank. The catalyst in the catalyst finished product tank must be in a self-circulating state, and then the catalyst delivery pump is measured by a mass flow meter and then delivered to the pulping tank for slurry preparation;

[0025] 2) Esterification I

[0026] Two direct esterification reactors are set up in the esterification part. The first stage of the esterification reaction is carried out in the first direct esterification reactor. The reactor is a fully mixed reactor with an agitator. The agitator shaft seal liquid is divided into two inlet and two outlet. The esterification rate is 90±1%, the temperature of the reacting material is 260℃, and the pressure is 0.15Mpa. The esterification I reactor 211 requires a lot of heat. The secondary heat medium is used to heat the material in the reactor through the inner coil and the jacket.

[0027] 3) Esterification II

[0028] The material after the reaction of the esterification I reactor enters the first chamber of the esterification II reactor through the pressure difference through the esterification II system liquid level regulating valve. The esterification II reactor is a horizontal reactor, which is divided into four chambers. The material enters the next chamber from one chamber in a plug flow manner. Each chamber is fully mixed. Each chamber is equipped with a stirrer. The discharge port is located at the bottom of the four chambers. The esterification rate of the material at the outlet of the esterification II reactor is 96%. The working temperature of the esterification II reactor is 268°C and the working pressure is 0.11Mpa. The remaining unfinished esterification continues to be completed in the polycondensation reaction. The esterification II reactor uses secondary heat medium to heat the material through the jacket and the inner coil. The material after the reaction of the esterification II reactor enters the polycondensation I reactor through the pressure difference;

[0029] The mixture of ethylene glycol vapor and water vapor produced by the esterification I reactor and the esterification II reactor is separated into ethylene glycol and water through a process tower. Light water and acetaldehyde are discharged from the top of the tower and condensed in the top condenser. In addition to part of the condensate being refluxed to the process tower, the rest is sent to the sewage treatment plant; the heavy component ethylene glycol and residue are discharged from the bottom of the tower, part of which is returned to the esterification I reactor and the esterification II reactor, and the other part is refluxed to the reused ethylene glycol tank;

[0030] 4) Polycondensation I

[0031] The polycondensation I reactor is a non-stirring reactor. The material flows out from the bottom of the esterification II reactor, and enters the inner chamber of the polycondensation I reactor from the bottom through the liquid level regulating valve of the polycondensation I system through the pressure difference, and the material then flows from the inner chamber to the outer chamber; since the polycondensation I reactor works under the conditions of 10Kpa vacuum and 270-272℃ of materials, ethylene glycol flashes and overflows from the material, and the entrained material tumbles upward together, which plays a stirring role, and the steam is captured and condensed by the first scraper condenser; the vacuum of the system is provided by a liquid ring vacuum pump; after the material in the polycondensation I reactor reaches a certain liquid level, it flows out from the lower side of the outer chamber, and enters the polycondensation II reactor from the bottom through the liquid level control valve of the polycondensation II system through the potential difference and pressure difference; the polycondensation I reactor Esterification and polycondensation reactions are carried out simultaneously in the kettle; the vaporized ethylene glycol is continuously pumped away by the vacuum system and enters the second scraper condenser, with a scraper agitator at the entrance to remove the polymers; the ethylene glycol vapor is captured by the 34°C ethylene glycol spray and flows into the second hot well, where the polymers and residues are filtered out through the coarse filter overflow and the double filter in the second hot well; the polymers deposited at the bottom of the second hot well should be discharged regularly; the filtered ethylene glycol is cooled to 34°C by a circulating pump through a cooler and sprayed on the second scraper condenser for use, and the excess ethylene glycol in the spray system can overflow through the vacuum system to the crude ethylene glycol collection and filling process tower for treatment; it can also overflow to the reused ethylene glycol receiving tank for reuse;

[0032] 5) Polycondensation II

[0033] Polycondensation II reactor: after the prepolymer enters the reactor, it continues to undergo polymerization reaction at 276±2℃ and 1Kpa. The outlet degree of polymerization is 26 and the intrinsic viscosity is 0.27dl / g. The polycondensation II reactor is a horizontal disc reactor. There are 5 partitions between each set of discs. Since the materials in the reactor undergo polycondensation reaction under vacuum, an ethylene glycol steam ejector is used to generate vacuum in the reactor. The materials in the polycondensation II reactor are pumped out by the prepolymer pump and then enter the post-polycondensation reactor through a three-way valve and a prepolymer filter;

[0034] 6) Post-condensation

[0035] The material from the polycondensation reactor II enters the post-polycondensation reactor, which is a horizontal reactor with a rotation speed of 2.5 rpm. The material undergoes polymerization reaction at a temperature of 282±2°C and a pressure of 100 pa. The viscosity of the material in the inlet area of ​​the reactor is relatively low, and the polymer is lifted up and dropped by the mesh disc to form a thin stream or a broken film. In the rear area of ​​the reactor, when the polymer reaches a certain viscosity, the polymer will stick to the disc to form a thin stream and a film when it is lifted up and dropped by the disc. The higher the viscosity, the closer it is to a film, thus forming a larger evaporation surface area, which is more conducive to the evaporation of ethylene glycol. The ethylene glycol vapor evaporated during the post-polycondensation reaction is reflected from the disc. The gas is extracted from the upper part of the reactor and sprayed and condensed with 28℃ ethylene glycol through the third scraper condenser; chilled water is used to cool the sprayed ethylene glycol in the recirculation cooling of the sprayed ethylene glycol; most of the fresh ethylene glycol required in the reaction system is added from this system; the excess ethylene glycol overflows to the recycled ethylene glycol tank for slurry preparation; the non-condensable gas from the third scraper condenser enters the ethylene glycol steam jet pump, which is divided into three stages. The power ethylene glycol steam of each stage comes from the ethylene glycol evaporator, the evaporator pressure is 0.1Mpa, the temperature is 203℃, and the non-condensable gas from the ethylene glycol jet is discharged after entering the vacuum liquid ring pump, and the viscosity is controlled at 0.65dl / g±0.2;

[0036] 7) Pelletizing and packaging

[0037] The polymer passes through melt pump I under vacuum conditions, part of the material passes through the melt filter and enters the pelletizing and packaging system, and part of the material enters the viscosity increasing system;

[0038] 8) Viscosity increase

[0039] The material from the post-polycondensation reactor enters the viscosity-increasing reactor; the ethylene glycol vapor evaporated during the viscosity-increasing reaction is extracted from the upper part of the disc reactor and condensed by spraying ethylene glycol at 26°C through the fourth scraper condenser; chilled water is used for cooling and circulating spraying of ethylene glycol in the spraying ethylene glycol recirculation cooling; most of the fresh ethylene glycol required in the reaction system is added from this system; the excess ethylene glycol overflows to the recycled ethylene glycol tank for slurry configuration; the non-condensable gas from the fourth scraper condenser enters the ethylene glycol liquid ring pump, and the non-condensable gas is discharged after reaching the vacuum liquid ring pump; the material reaches the viscosity value required by the subsequent process of 0.75dl / g-0.8dl / g, and the material is transported by melt pump II to the melt inlet of the subsequent film drawing equipment for the film drawing process;

[0040] 9) Film drawing

[0041] The material melt thickened by the thickening reactor is sent to the film drawing system through melt pump II for direct film drawing;

[0042] 10) Film packaging

[0043] After being stretched by the film stretching system, the film is transported to the film material packaging system for packaging.

[0044] A system for producing high-viscosity decorative base film by using PET with great light comprises a raw material and auxiliary material preparation system, and an esterification I system and an esterification II system which are connected by pumping in sequence, wherein the esterification II system is connected to a polycondensation I system for performing a pre-polycondensation reaction on an esterified product and producing a prepolymer, wherein the discharge port of the polycondensation I system is connected to the polycondensation II system, wherein the polycondensation II system is connected by pumping to a post-polycondensation system, wherein the outlet of the post-polycondensation system is connected by pumping to a melt filter via a melt pump I, wherein the melt filter is respectively connected by pumping to a pelletizing packaging system and a viscosity-increasing system, wherein the viscosity-increasing system is connected by pumping to a film-drawing system via a melt pump II, wherein the film-drawing system is connected to a film material packaging system, wherein the viscosity-increasing system comprises a viscosity-increasing reactor connected by pumping to the melt filter, and a fourth scraper condenser connected by pumping to the viscosity-increasing reactor, wherein the fourth scraper condenser is connected to a vacuum pump via a top riser, wherein the medium outlet of the fourth scraper condenser is connected to a hot well, and wherein the vacuum pump is connected to the fourth scraper condenser via a bypass pipe connecting plate A / B exchanger via the hot well.

[0045] Preferably, the viscosity-increasing reactor is a horizontal reactor.

[0046] Preferably, the rotation speed of the horizontal reactor is 2.2 rpm.

[0047] Preferably, the esterification I system comprises an esterification I reactor, both ends of which are provided with direct esterification reactors for the first stage esterification reaction, and an agitator is provided inside, and the agitator shaft seal liquid enters and exits in two ways.

[0048] Preferably, the esterification I reactor is a fully mixed reactor.

[0049] Preferably, the gas risers at the top of the esterification system I and the esterification system II are connected to process towers, the bottom of the process towers are recycled to the esterification system I and the esterification system II via a pipeline pump connected to a distillation tower and output PTA, the process towers are connected to an air cooler via a bypass line, and the pressure of the air cooler is controlled by PRC and FRC.

[0050] Preferably, the gas phase outlet of the polycondensation I system is connected to the first scraper condenser, the gas phase outlet of the polycondensation II system is connected to the second scraper condenser, and the gas phase outlet of the post-polycondensation system is connected to the third scraper condenser. The medium outlet of the first scraper condenser is connected to the first hot well, the medium outlet of the polycondensation II system is connected to the second hot well, and the medium outlet of the post-polycondensation system is connected to the third hot well. The first hot well, the second hot well, and the third hot well are respectively connected to the first heat exchanger, the second heat exchanger, and the third heat exchanger. The outlets of the first heat exchanger, the second heat exchanger, and the third heat exchanger are respectively connected to the spray outlets of the first scraper condenser, the second scraper condenser, and the third scraper condenser.

[0051] Preferably, the esterification II system comprises an esterification II reactor, and the esterification II reactor is a horizontal reactor.

[0052] Preferably, the raw and auxiliary material preparation system includes a PTA silo, the outlet of the PTA silo is connected to a slurry preparation tank, and the slurry preparation tank is pumped and connected to a slurry finished product tank and the esterification I reaction kettle of the esterification I system via a slurry pump.

[0053] Compared with the prior art, the present invention has the following beneficial effects:

[0054] 1. It is conducive to the circulation, evaporation and replenishment of ethylene glycol;

[0055] 2. Improved the esterification efficiency of PTA polymer;

[0056] 3. Increased PTA polymer viscosity. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 is a flow chart of the method of the present invention;

[0058] Figure 2 It is a schematic diagram of the raw material system, esterification I system and esterification II system of the present invention;

[0059] Figure 3 It is a schematic diagram of the process tower of the polycondensation system I and the polycondensation system II of the present invention;

[0060] Figure 4 It is a schematic diagram of the scraper condenser and the first vacuum system of the present invention;

[0061] Figure 5 It is a schematic diagram of the post-condensation system of the present invention;

[0062] Figure 6 It is a schematic diagram of the pelletizing and packaging system of the present invention;

[0063] Figure 7 Schematic diagram of the viscosity increasing system of the present invention. DETAILED DESCRIPTION

[0064] The specific embodiments of the present invention are further described below in conjunction with the accompanying drawings. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0065] Reference Figure 1-7 A system for producing high-viscosity decorative base film of PET with great light comprises a raw material and auxiliary material preparation system 1, and an esterification system I 2 and an esterification system II 3 which are connected by pumping in sequence, wherein the esterification system II 3 is connected to a polycondensation system I 4 for performing a pre-polycondensation reaction on the esterified product and producing a prepolymer, and the discharge port of the polycondensation system I 4 is connected to a polycondensation system II 5, and the polycondensation system II 5 is connected to a post-polycondensation system 6 by pumping, and the outlet of the post-polycondensation system 6 is connected to a melt filter 62 by pumping through a melt pump I 61, and the melt filter 62 is connected to a pelletizing and packaging system 7 and an increasing system 8 respectively by pumping. The viscosity enhancing system 8 is connected to the film drawing system 9 by means of a melt pump II 11, and the film drawing system 9 is connected to the film material packaging system 10. The viscosity enhancing system 8 includes a viscosity enhancing reactor 81 which is pumped connected to the melt filter 62, and a fourth scraper condenser 82 which is pumped connected to the viscosity enhancing reactor 81, and the fourth scraper condenser 82 is connected to the vacuum pump 83 via the top air riser, and the medium outlet of the fourth scraper condenser 82 is connected to the hot well 84, and the vacuum pump 83 is connected to the fourth scraper condenser 82 via the bypass pipe connecting plate A / B85 and the hot well 84.

[0066] Specifically, the viscosity-increasing reactor 81 is a horizontal reactor with a rotation speed of 2.2 rpm. The material is polymerized at a temperature of 282±1°C and a pressure of 70 pa. The material from the post-condensation reactor enters the viscosity-increasing reactor. The viscosity of the material in the inlet area of ​​the reactor is low, and the polymer is lifted and dropped by the mesh disc to form a thin stream or a broken film. In the rear area of ​​the reactor, when the polymer reaches a certain viscosity, the polymer will stick to the disc to form a thin stream and a thin film when it is lifted and dropped by the disc. The higher the viscosity, the closer it is to a film, thus forming a larger evaporation surface area, which is more conducive to the evaporation of ethylene glycol. The ethylene glycol vapor evaporated during the viscosity-increasing reaction is extracted from the upper part of the disc reactor and condensed by spraying ethylene glycol at 26°C through a scraper condenser. Chilled water is used to cool the circulating spray ethylene glycol in the spray ethylene glycol recirculation cooling. Most of the fresh ethylene glycol required in the reaction system is added from this system. The excess ethylene glycol overflows to the recycled ethylene glycol tank for slurry configuration. The non-condensable gas from the scraper condenser enters the glycol liquid ring pump, and then is discharged after reaching the vacuum liquid ring pump. When the material reaches the required viscosity value of the subsequent process (0.75dl / g--0.8dl / g), the material is transported by the melt pump to the melt inlet of the subsequent film drawing equipment for the film drawing process.

[0067] Specifically, the esterification I system 2 includes an esterification I reactor 211, which is a fully mixed reactor. Direct esterification reactors 212 are provided at both ends of the esterification I reactor 211 for the first stage of esterification reaction. A stirrer is provided inside, and the shaft seal liquid of the stirrer enters and exits in two ways. The esterification rate is 90±1%, the temperature of the reacted material is 260°C, and the pressure is 0.15Mpa. The esterification I reactor 211 uses secondary heat medium to heat the material in the reactor through the inner coil and the jacket. Two-stage direct esterification reactors are set in the esterification part, and the first stage of the esterification reaction is carried out in the first stage of the direct esterification reactor.

[0068] Specifically, the gas riser at the top of the esterification system I 2 and the esterification system II 3 is connected to the process tower 12, and the bottom of the process tower 12 is recycled to the esterification system I 2 and the esterification system II 3 through the pipeline pump 14 connected to the distillation tower 13 and outputs PT. The process tower 12 is connected to the air cooler 15 through the bypass pipeline, and the air cooler 15 controls the pressure through the PRC (pressure controller) and the FRC (flow recording controller). The mixture of ethylene glycol vapor and water vapor (containing a small amount of low boiling substances) produced by the esterification I reactor 211 and the esterification II reactor 311 is separated into ethylene glycol and water through the process tower 12, and light water and acetaldehyde are discharged from the top of the tower and condensed in the top condenser. Except for part of the condensate refluxed to the process tower 12, the rest is sent to the sewage treatment plant. The recombinant ethylene glycol and residue are discharged from the bottom of the tower, part of which is returned to the esterification I reactor 211 and the esterification II reactor 311, and the other part is refluxed to the recycled ethylene glycol tank.

[0069] Specifically, the gas phase outlet of the polycondensation I system 4 is connected to the first scraper condenser 41, the gas phase outlet of the polycondensation II system 5 is connected to the second scraper condenser 51, and the gas phase outlet of the post-polycondensation system 6 is connected to the third scraper condenser 63. The medium outlet of the first scraper condenser 41 is connected to the first hot well 42, the medium outlet of the polycondensation II system 5 is connected to the second hot well 52, and the medium outlet of the post-polycondensation system 6 is connected to the third hot well 64. The first hot well 42, the second hot well 52, and the third hot well 64 are respectively connected to the first heat exchanger 421, the second heat exchanger 521, and the third heat exchanger 641. The outlets of the first heat exchanger 421, the second heat exchanger 521, and the third heat exchanger 641 are respectively connected to the spray outlets of the first scraper condenser 41, the second scraper condenser 51, and the third scraper condenser 63.

[0070] Specifically, the esterification II system 3 includes an esterification II reactor 311, which is a horizontal reactor, divided into four chambers. The material enters the first chamber through the liquid level regulating valve 312 of the esterification II reactor 311 by pressure difference, and enters the next chamber from the first chamber in a plug flow manner. Each chamber is fully mixed, and each chamber is equipped with a stirrer. The discharge port is located at the bottom of the four chambers. The esterification rate of the material at the outlet of the esterification II reactor 311 is 96%, the working temperature is 268°C, and the working pressure is 0.11Mpa. The esterification II reactor 311 uses secondary heat medium to heat the material through the jacket and the inner coil.

[0071] Specifically, the raw and auxiliary material preparation system includes a PTA silo 131, the outlet of the PTA silo 131 is connected to a slurry preparation tank 132, and the slurry preparation tank 132 is pumped and connected to a slurry finished product tank 134 and is pumped and connected to the esterification I reactor 211 of the esterification I system 2 via a slurry pump 133.

[0072] A method for producing a high-viscosity decorative base film using high-gloss PET comprises the following steps:

[0073] 1. Preparation of raw and auxiliary materials

[0074] The ethylene glycol in the recycled ethylene glycol receiving tank is measured by the meter and then quantitatively enters the slurry preparation tank 132. After the fresh ethylene glycol and the catalyst ethylene glycol solution are placed in the slurry preparation tank 132, PTA is evenly placed in the slurry preparation tank 132 with a ton package of PTA as the measurement under stirring to make slurry. The slurry in the slurry intermediate tank passes through the screw pump 135, then through the mass flow meter 136 (which can also measure the slurry density), and through the three-way valve 137 into the esterification I reactor 211. The density meter can monitor the slurry molar ratio, and the slurry can also be circulated back to the slurry intermediate tank through the three-way valve 137. The liquid level control output of the esterification I system 2 is converted and used as the set value of the mass flow meter 136 to control the speed of the screw pump 135. Catalyst preparation (taking ethylene glycol antimony preparation as an example), first add a specified amount of fresh ethylene glycol to the catalyst preparation tank through a flow meter, start the agitator, and heat up at the same time, control the temperature at 110°C, keep it warm for 0.5 hours, add a specified amount of catalyst ethylene glycol antimony, and continue to stir for 2 hours. After it is dissolved at the specified temperature, prepare a 2.0% (wt) concentration solution in the catalyst preparation tank. After the catalyst ethylene glycol solution prepared in the catalyst preparation tank is analyzed and found to be qualified, it is filtered through a filter and moved to the catalyst finished product tank. The catalyst in the catalyst finished product tank must be in a self-circulating state. The catalyst delivery pump then measures it through a mass flow meter and delivers it to the pulping tank for slurry preparation.

[0075] 2. Esterification I

[0076] Two direct esterification reactors are set up in the esterification part. The first stage of the esterification reaction is carried out in the first direct esterification reactor. The reactor is a fully mixed reactor with a stirrer inside. The stirrer shaft seal liquid is divided into two inlets and two outlets. The esterification rate is 90±1%, the temperature of the reacting material is 260℃, and the pressure is 0.15Mpa. The esterification I reactor 211 requires a lot of heat, and the secondary heat medium is used to heat the material in the reactor through the inner coil and the jacket.

[0077] 3. Esterification II

[0078] The material after the reaction in the esterification I reactor 211 enters the first chamber of the esterification II reactor 311 through the pressure difference through the esterification II system 3 liquid level regulating valve. The esterification II reactor 311 is a horizontal reactor with four chambers. The material enters the next chamber from one chamber in a plug flow manner. Each chamber is fully mixed and each chamber is equipped with an agitator. The discharge port is located at the bottom of the four chambers. The esterification rate of the material at the outlet of the esterification II reactor 311 is 96%. The working temperature of the esterification II reactor 311 is 268℃, and the working pressure is 0.11Mpa. The remaining unfinished esterification continues to be completed in the polycondensation reaction. The esterification II reactor 311 uses secondary heat medium to heat the material through the jacket and the inner coil. The material after the reaction in the esterification II reactor 311 enters the polycondensation I reactor 411 through the pressure difference.

[0079] The mixture of ethylene glycol vapor and water vapor (containing a small amount of low-boiling substances) produced by the esterification I reactor 211 and the esterification II reactor 311 is separated into ethylene glycol and water through the process tower 12. Light water and acetaldehyde are discharged from the top of the tower and condensed in the top condenser. The condensate is partially refluxed to the process tower 12, and the rest is sent to the sewage treatment plant. The recombinant ethylene glycol and residue are discharged from the bottom of the tower, part of which is returned to the esterification I reactor 211 and the esterification II reactor 311, and the other part is refluxed to the recycled ethylene glycol tank.

[0080] 4. Polycondensation I

[0081] The polycondensation I reactor 411 is a non-stirring reactor. The material flows out from the bottom of the esterification II reactor 311, and enters the inner chamber of the polycondensation I reactor 411 from the bottom through the liquid level regulating valve of the polycondensation I system 4 through the pressure difference, and the material then flows from the inner chamber to the outer chamber; since the polycondensation I reactor 411 works under the conditions of 10Kpa vacuum and 270-272℃ of the material, ethylene glycol flashes and overflows from the material, and the entrained material tumbles upward together, which plays a stirring role, and the steam is captured and condensed by the first scraper condenser 41; the vacuum of the system is provided by a liquid ring vacuum pump; after the material in the polycondensation I reactor 411 reaches a certain liquid level, it flows out through the lower side of the outer chamber, and enters the polycondensation II reactor 511 from the bottom through the liquid level control valve of the polycondensation II system 5 through the potential difference and pressure difference; The esterification and polycondensation reactions are carried out simultaneously in the poly I reactor 411; the vaporized ethylene glycol is continuously pumped away by the vacuum system, and the pumped ethylene glycol enters the second scraper condenser 51, and a scraper-type agitator is provided at the entrance to remove the polymers; the ethylene glycol vapor is captured by the 34°C ethylene glycol spray, and then flows into the second hot well 52, and the polymers and residues are filtered out through the coarse filter overflow and the double filter in the second hot well 52; the polymers deposited at the bottom of the second hot well 52 should be discharged regularly; the filtered ethylene glycol is cooled to 34°C by a circulating pump through a cooler, and is sprayed in the second scraper condenser 51 for use, and the excess ethylene glycol in the spraying system can overflow through the vacuum system to the crude ethylene glycol collection and filling process tower 12 for treatment; it can also overflow to the reused ethylene glycol receiving tank for reuse;

[0082] 5. Polycondensation II

[0083] Polycondensation II reactor 511, after the prepolymer enters the reactor, it continues to undergo polymerization reaction at 276±2℃ and 1Kpa, with an outlet degree of polymerization of 26 and an intrinsic viscosity of 0.27dl / g. Polycondensation II reactor 511 is a horizontal disc reactor, with 5 partitions between each set of discs. Since the material in the reactor undergoes polycondensation reaction under vacuum, an ethylene glycol steam ejector is used to generate vacuum in the reactor. The material in polycondensation II reactor 511 is pumped out through a prepolymer pump, and then enters a post-polycondensation reactor 611 through a three-way valve and a prepolymer filter;

[0084] 6. Post-condensation

[0085] The material from the polycondensation II reactor 511 enters the post-polycondensation reactor 611, which is a horizontal reactor with a rotation speed of 2.5 rpm. The material undergoes polymerization reaction at a temperature of 282±2°C and a pressure of 100 pa. The viscosity of the material in the inlet area of ​​the reactor is relatively low, and the polymer is lifted up and dropped by the mesh disc to form a thin stream or a broken film. In the rear area of ​​the reactor, when the polymer reaches a certain viscosity, the polymer will stick to the disc to form a thin stream and a film when it is lifted up and dropped by the disc. The higher the viscosity, the closer it is to a film, thus forming a larger evaporation surface area, which is more conducive to the evaporation of ethylene glycol. The ethylene glycol vapor evaporated during the post-polycondensation reaction will be discharged from the disc. The gas is extracted from the upper part of the reactor and sprayed and condensed with 28°C ethylene glycol through the third scraper condenser 63; chilled water is used for cooling the sprayed ethylene glycol in the recirculation cooling of the sprayed ethylene glycol; most of the fresh ethylene glycol required in the reaction system is added from this system; the excess ethylene glycol overflows to the recycled ethylene glycol tank for slurry preparation; the non-condensable gas from the third scraper condenser 63 enters the ethylene glycol steam jet pump, which is divided into three stages. The power ethylene glycol steam of each stage comes from the ethylene glycol evaporator, the evaporator pressure is 0.1Mpa, the temperature is 203°C, and the non-condensable gas from the ethylene glycol jet is discharged after entering the vacuum liquid ring pump, and the viscosity is controlled at 0.65dl / g±0.2;

[0086] 7. Pelletizing and packaging

[0087] The polymer passes through melt pump I 61 under vacuum conditions, a portion of the material passes through melt filter 62 and enters pelletizing and packaging system 7, and a portion of the material enters viscosity increasing system 8;

[0088] 8. Viscosity

[0089] The material from the post-polycondensation reactor 611 enters the viscosity-increasing reactor 811; the ethylene glycol vapor evaporated during the viscosity-increasing reaction is extracted from the upper part of the disc reactor, and condensed by spraying ethylene glycol at 26°C through the fourth scraper condenser 82; chilled water is used for cooling and circulating the sprayed ethylene glycol in the sprayed ethylene glycol recycling cooling; most of the fresh ethylene glycol required in the reaction system is added from this system; the excess ethylene glycol overflows to the recycled ethylene glycol tank for slurry configuration; the non-condensable gas from the fourth scraper condenser 82 enters the ethylene glycol liquid ring pump, and the non-condensable gas is discharged after reaching the vacuum liquid ring pump; the material reaches the viscosity value required by the subsequent process of 0.75dl / g-0.8dl / g, and the material is transported by the melt pump II11 to the melt inlet of the subsequent film drawing equipment for the film drawing process;

[0090] 9. Film drawing

[0091] The material melt thickened by the thickening reactor 811 is sent to the film drawing system 9 through the melt pump II 11 for direct film drawing;

[0092] 10. Film packaging

[0093] After being stretched by the film stretching system 9, the film is transported to the film material packaging system 10 for packaging.

[0094] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions and variations of these embodiments are made without departing from the principles and spirit of the present invention, and still fall within the scope of protection of the present invention.

Claims

1. A method for producing a high-viscosity decorative base film using high-gloss PET, characterized in that: The following steps are involved: 1) Preparation of raw and auxiliary materials The ethylene glycol in the recycled ethylene glycol receiving tank is measured by a meter and then quantitatively enters the slurry preparation tank (132). After the fresh ethylene glycol and the catalyst ethylene glycol solution are placed in the slurry preparation tank (132), PTA is evenly placed in the slurry preparation tank (132) with a ton bag of PTA as the measurement under stirring to prepare slurry. The slurry in the slurry intermediate tank is passed through a screw pump (135), a mass flow meter (136), and a three-way valve (137) to enter the esterification I reactor (211). The density meter can monitor the molar ratio of the slurry. The slurry can also be circulated back to the slurry intermediate tank through the three-way valve (137). The liquid level control output of the esterification I system (2) is converted and used as the set value of the mass flow meter (136). to control the rotation speed of the screw pump (135); catalyst preparation, first add a specified amount of fresh ethylene glycol to the catalyst preparation tank through a flow meter, start the agitator, and heat up at the same time, control the temperature at 110°C, keep it warm for 0.5h, add a specified amount of catalyst ethylene glycol antimony, and continue to stir for 2h after heating. After dissolving at the specified temperature, prepare a solution with a concentration of 2.0% (wt) in the catalyst preparation tank. After the catalyst ethylene glycol solution prepared in the catalyst preparation tank is analyzed and found to be qualified, it is filtered through a filter and then transferred to the catalyst finished product tank. The catalyst in the catalyst finished product tank must be in a self-circulating state, and then the catalyst delivery pump is measured by a mass flow meter and then delivered to the pulping tank for slurry preparation; 2) Esterification I Two direct esterification reactors are set up in the esterification part. The first stage of the esterification reaction is carried out in the first direct esterification reactor. The reactor is a fully mixed reactor with an agitator. The agitator shaft seal liquid is divided into two inlet and two outlet. The esterification rate is 90±1%, the temperature of the reacting material is 260℃, and the pressure is 0.15Mpa. The esterification I reactor 211 requires a lot of heat. The secondary heat medium is used to heat the material in the reactor through the inner coil and the jacket. 3) Esterification II The material after the reaction in the esterification I reactor (211) enters the first chamber of the esterification II reactor (311) through the pressure difference through the liquid level regulating valve of the esterification II system (3). The esterification II reactor (311) is a horizontal reactor, which is divided into four chambers. The material enters the next chamber from one chamber in a plug flow manner. Each chamber is fully mixed. Each chamber is provided with a stirrer. The discharge port is provided at the bottom of the four chambers. The esterification rate of the material at the outlet of the esterification II reactor (311) is 96%. The working temperature of the esterification II reactor (311) is 268° C. and the working pressure is 0.11 MPa. The remaining unfinished esterification is continued to be completed in the polycondensation reaction. The esterification II reactor (311) uses a secondary heat medium to heat the material through the jacket and the inner coil. The material after the reaction in the esterification II reactor (311) enters the polycondensation I reactor (411) through the pressure difference. The mixture of ethylene glycol vapor and water vapor produced by the esterification I reactor (211) and the esterification II reactor (311) is separated into ethylene glycol and water through a process tower (12). Light water and acetaldehyde are discharged from the top of the tower and condensed in a tower top condenser. A portion of the condensate is refluxed to the process tower (12), and the rest is sent to a sewage treatment plant. The heavy component ethylene glycol and residue are discharged from the bottom of the tower, a portion of which is returned to the esterification I reactor (211) and the esterification II reactor (311), and the other portion is refluxed to the recycled ethylene glycol tank. 4) Polycondensation I The polycondensation I reactor (411) is a non-stirring reactor. The material flows out from the bottom of the esterification II reactor (311), and enters the inner chamber of the polycondensation I reactor (411) from the bottom through the liquid level regulating valve of the polycondensation I system (4) due to the pressure difference. The material then flows from the inner chamber to the outer chamber. Since the polycondensation I reactor (411) operates under the conditions of 10Kpa vacuum and 270-272°C of the material, ethylene glycol flashes and overflows from the material, and the entrained material tumbles upward, playing a stirring role. The steam is captured and condensed by the first scraper condenser (41). The vacuum of the system is provided by a liquid ring vacuum pump. The polycondensation I reactor (41 1) When the material reaches a certain liquid level, it flows out from the lower side of the outer chamber, and enters the polycondensation II reactor (511) from the bottom through the liquid level control valve of the polycondensation II system (5) through the potential difference and pressure difference; the esterification and polycondensation reactions are carried out simultaneously in the polycondensation I reactor (411); the vaporized ethylene glycol is continuously extracted by the vacuum system, and the extracted ethylene glycol enters the second scraper condenser (51), and a scraper-type agitator is provided at the inlet to remove the polymer; the ethylene glycol vapor is captured by the 34° C. ethylene glycol spray, and then flows into the second hot well (52), and the polymer and residue are filtered out through the coarse filter overflow and the double filter in the second hot well (52); The polymer deposited at the bottom of the second hot well (52) needs to be discharged regularly; the filtered ethylene glycol is cooled to 34°C by a circulating pump through a cooler and sprayed on the second scraper condenser (51) for use. The excess ethylene glycol in the spraying system can overflow through the vacuum system to the crude ethylene glycol collection and delivery process tower (12) for treatment; it can also overflow to the recycled ethylene glycol receiving tank for reuse; 5) Polycondensation II Polycondensation II reactor (511), after the prepolymer enters the reactor, it continues to undergo polymerization reaction at 276±2°C and 1Kpa, with an outlet degree of polymerization of 26 and an intrinsic viscosity of 0.27dl / g. The polycondensation II reactor (511) is a horizontal disc reactor, with 5 partitions provided between each set of discs. Since the material in the reactor undergoes polycondensation reaction under vacuum, a glycol steam ejector is used to generate vacuum in the reactor. The material in the polycondensation II reactor (511) is pumped out through a prepolymer pump and then enters a post-polycondensation reactor (611) through a three-way valve and a prepolymer filter; 6) Post-condensation The material from the polycondensation II reactor (511) enters the post-polycondensation reactor (611), which is a horizontal reactor with a rotation speed of 2.5 rpm. The material undergoes polymerization reaction at a temperature of 282±2°C and a pressure of 100 pa. The viscosity of the material in the inlet area of ​​the reactor is relatively low, and the polymer is lifted up and dropped by the mesh disc to form a thin stream or a broken film. In the rear area of ​​the reactor, when the polymer reaches a certain viscosity, the polymer is lifted up and dropped by the disc and adheres to the disc to form a thin stream and a film. The higher the viscosity, the closer it is to a film, thus forming a larger evaporation surface area, which is more conducive to the evaporation of ethylene glycol. The ethylene glycol vapor evaporated during the post-polycondensation reaction is discharged from the disc. The gas is extracted from the upper part of the reactor and sprayed with 28°C ethylene glycol through the third scraper condenser (63) for condensation; chilled water is used for cooling the sprayed ethylene glycol in the recirculation cooling of the sprayed ethylene glycol; most of the fresh ethylene glycol required in the reaction system is added from this system; the excess ethylene glycol overflows into the recycled ethylene glycol tank for slurry preparation; the non-condensable gas from the third scraper condenser (63) enters the ethylene glycol steam jet pump, which is divided into three stages. The power ethylene glycol steam of each stage comes from the ethylene glycol evaporator, the evaporator pressure is 0.1Mpa, the temperature is 203°C, and the non-condensable gas from the ethylene glycol jet pump is discharged after entering the vacuum liquid ring pump, and the viscosity is controlled at 0.65dl / g±0.2; 7) Pelletizing and packaging The polymer passes through melt pump I (61) under vacuum conditions, a portion of the material passes through a melt filter (62) and enters a pelletizing and packaging system (7), and a portion of the material enters a viscosity increasing system (8); 8) Viscosity increase The material from the post-polycondensation reactor (611) enters the viscosity-increasing reactor (811); the ethylene glycol vapor evaporated during the viscosity-increasing reaction is extracted from the upper part of the disc reactor and condensed by spraying ethylene glycol at 26°C through the fourth scraper condenser (82); chilled water is used for cooling the circulating spray ethylene glycol in the spray ethylene glycol recycling cooling; most of the fresh ethylene glycol required in the reaction system is added from this system; the excess ethylene glycol overflows to the recycled ethylene glycol tank for slurry preparation; the non-condensable gas from the fourth scraper condenser (82) enters the ethylene glycol liquid ring pump, and the non-condensable gas is discharged after reaching the vacuum liquid ring pump; the material reaches the viscosity value required by the subsequent process of 0.75dl / g-0.8dl / g, and the material is transported by the melt pump II (11) to the melt inlet of the subsequent film drawing equipment to carry out the film drawing process; 9) Film drawing The material melt thickened by the thickening reaction kettle (811) is sent to the film drawing system (9) through the melt pump II (11) for direct film drawing; 10) Film packaging After being drawn by the film drawing system (9), the film is transported to the film material packaging system (10) for packaging.

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