Production system of copolyester white chips for PETG (Polyethylene Terephthalate Glycol) heat-shrinkable white film

Abstract

The utility model discloses a production system of a copolyester white chip for a PETG heat shrinkage white film. The production system comprises a slurry preparation kettle, an esterification kettle I, an esterification kettle II, a titanium dioxide preparation system, a preshrinking kettle I, a preshrinking kettle II, a final shrinkage kettle and a granulator. The preparation method comprises the following steps: preparing a titanium dioxide EG solution in a titanium dioxide preparation system, putting the catalyst, the titanium dioxide EG solution, PTA, EG and CHDM into a slurry preparation kettle, mixing to obtain slurry, enabling the slurry to sequentially pass through an esterification kettle I, an esterification kettle II, a preshrinking kettle I, a preshrinking kettle II and a final shrinkage kettle to obtain PETG melt, and granulating and slicing the PETG melt through a granulator. And adding a titanium dioxide EG solution into the slurry preparation kettle, the esterification kettle I and the esterification kettle II, and finally directly producing white PETG slices, wherein the titanium dioxide concentration in the white PETG slices reaches 18wt%.

Description

Technical Field

[0001] The utility model belongs to the field of polymer materials, and particularly relates to a production system for copolyester white chips for PETG heat-shrinkable white films. Background Art

[0002] PETG material is a transparent plastic, an amorphous copolyester, and its full name is polyethylene terephthalate-1,4-cyclohexanedimethanol ester. PETG in the prior art is a product obtained by direct esterification and then polycondensation of three monomers, namely terephthalic acid (PTA), ethylene glycol (EG), and 1,4-cyclohexanedimethanol (CHDM).

[0003] The existing production process of PETG heat-shrinkable white film is to feed PETG chips into the main feeding screw for extrusion and melting, and another side feeding screw is used to feed titanium dioxide PETG white masterbatch for extrusion and melting, and then mix it with the PETG melt of the main screw and send it into the film head for film drawing, so as to produce PETG white film.

[0004] Titanium dioxide PETG white masterbatch is prepared by grinding PETG chips into powder, mixing them with titanium dioxide powder and then melting and blending. The intrinsic viscosity of the chips obtained by the blending method is as low as 0.45, and the mixing of titanium dioxide is uneven. When mixed with the PETG chip melt with a viscosity of about 0.75 during the subsequent white film production, the viscosity difference is too large, resulting in uneven melt quality during the subsequent film drawing and unstable production. Summary of the Utility Model

[0005] The purpose of the utility model is to provide a production system and a production method for copolyester white chips for PETG heat-shrinkable white films. A titanium dioxide preparation system is connected to the first esterification kettle and the second esterification kettle, and a titanium dioxide EG solution is added during the esterification process, so that the titanium dioxide concentration in the final finished chips reaches 18wt%.

[0006] In order to achieve the above purpose, the utility model adopts the following technical scheme:

[0007] The production system for copolyester white chips for PETG heat-shrinkable white films includes

[0008] A slurry preparation kettle, which mixes a catalyst, a titanium dioxide EG solution, CHDM, PTA, and EG according to a ratio to form a slurry;

[0009] An esterification system, which heats and esterifies the slurry fed from the slurry preparation kettle to obtain an esterified product;

[0010] A titanium dioxide preparation system, which prepares the titanium dioxide EG solution and flows the titanium dioxide EG solution into the slurry preparation kettle and the esterification system;

[0011] A pre - shrinking system that performs polycondensation reaction on the esterified product flowing out of the esterification system to obtain PETG melt;

[0012] A pelletizer that pellets the PETG melt to obtain copolyester white chips for PETG heat - shrinkable white film.

[0013] The esterification system is connected to the titanium dioxide finished product tank of titanium dioxide EG solution. When the esterification system reacts, the titanium dioxide EG solution in the titanium dioxide finished product tank is pumped into the esterification system.

[0014] The titanium dioxide preparation system prepares titanium dioxide EG solution, adds the titanium dioxide EG solution in the esterification system, and finally directly produces white PETG chips.

[0015] Furthermore, the esterification system includes

[0016] The first esterification kettle that heats the slurry pumped from the slurry preparation kettle to carry out esterification reaction to obtain the primary esterified product;

[0017] The second esterification kettle that reheats the primary esterified product flowing out of the first esterification kettle to carry out esterification to obtain the secondary esterified product.

[0018] The slurry is fully esterified through the first esterification kettle and the second esterification kettle.

[0019] Furthermore, both the first esterification kettle and the second esterification kettle are connected to the same process tower, and the process tower is connected to the stripping tower.

[0020] The main function of the process tower is to remove the by - product water from the first esterification kettle and the second esterification kettle. The boiling point of EG is 197°C, and the boiling point of water is 100°C. The EG and water from the first esterification kettle and the second esterification kettle remove water through the difference in boiling points.

[0021] The main function of the stripping tower is to reduce the COD of the esterification water, reducing the COD from 25000 - 30000 mg / L to about 3500 mg / L. The esterification water contains flammable and explosive low - boiling substances (mainly aldehydes and ethers). If it is directly sent to the wastewater treatment without passing through the stripping tower, when aerating in the regulating tank, some organic substances will be directly discharged into the atmosphere. These organic substances discharged into the atmosphere through aeration will have a certain impact on the surrounding environment, and there will also be a strong odor on the downwind side of the wastewater treatment. After being treated by this set of stripping tower devices, the volatile organic substances are directly sent to the boiler and will not enter the atmosphere after wastewater treatment. It reduces the burden of wastewater treatment and the cost of wastewater treatment, which is both energy - saving and environmentally friendly.

[0022] Furthermore, the pre - shrinking system includes

[0023] The first pre - shrinking kettle that performs pre - polycondensation reaction on the esterified product flowing out of the esterification system to obtain the primary pre - condensate;

[0024] The second pre-condensation kettle re-condenses the primary pre-condensate flowing out of the first pre-condensation kettle to obtain the secondary pre-condensate;

[0025] The final condensation kettle polycondenses the secondary pre-condensate flowing out of the second pre-condensation kettle to obtain the PETG melt.

[0026] Through three polycondensation kettles, the viscosity of the material is increased through stepwise polycondensation reaction, and at the same time, the vacuum degree in the reaction kettle is gradually reduced to extract the small molecules generated by the reaction.

[0027] Furthermore, the first pre-condensation kettle, the second pre-condensation kettle, and the final condensation kettle are respectively connected to their own scraper condensers. The scraper condenser is connected to a vacuum ejector pump. The vacuum ejector pump is connected to an EG evaporator and a scrubbing tower. A liquid ring vacuum pump is connected between the scrubbing tower and the vacuum ejector pump.

[0028] The first polycondensation kettle, the second polycondensation kettle, and the final condensation kettle are all equipped with independent scraper condensers. The main function of the scraper condenser is to capture small molecules such as EG vapor and water vapor in the system and the oligomers entrained in the vapor through the way of alternating heat and cold. The small molecule vapor is captured by the EG spray of the EG circulation system, and the oligomers are captured by the scraper, the hot well basket, the residue box, and the filter. The non-condensable gas in the polycondensation system is extracted by the vacuum ejector pump and the liquid ring vacuum pump. The EG evaporator generates the motive steam for the vacuum system, and the steam generates a vacuum through three-stage injection and spraying to extract the small molecule gas in the reaction kettle.

[0029] Furthermore, the titanium dioxide preparation system includes a preparation tank, a finished product tank, a finished product transfer pump, and a finished product filter. Titanium dioxide and EG solution are stirred in the preparation tank to form the primary titanium dioxide EG solution. After the primary titanium dioxide EG solution flows into the finished product tank, it is made into the titanium dioxide EG solution through the finished product transfer pump and the finished product filter.

[0030] Due to the adoption of the above technical solutions, the utility model has the following beneficial effects:

[0031] The titanium dioxide EG solution is added to the slurry preparation kettle, the first esterification kettle, and the second esterification kettle by using the titanium dioxide preparation system. The titanium dioxide EG solution is added during the esterification process, and finally, white PETG chips are directly produced. The concentration of titanium dioxide in the chips reaches 18wt%.

[0032] The chips produced by using this system have high viscosity, and the titanium dioxide is evenly mixed. The side feeding screw is omitted during the downstream film drawing process, saving electric energy and equipment investment, and improving the product quality. Description of the Drawings

[0033] The following further describes the present utility model with reference to the drawings.

[0034] Figure 1It is a schematic structural diagram of a copolyester white chip production system for PETG heat-shrinkable white film.

[0035] Figure 2 It is a schematic structural diagram of a titanium dioxide preparation system. Specific embodiments

[0036] As Figure 1 The copolyester white chip production system for PETG heat-shrinkable white film shown in the figure includes a slurry preparation kettle 1 connected in sequence, which mixes the catalyst, titanium dioxide EG solution, CHDM, PTA, and EG in the raw materials according to the ratio to form a slurry;

[0037] The first esterification kettle 2 heats the slurry fed from the slurry preparation kettle 1 to carry out an esterification reaction to obtain a primary esterified product;

[0038] The second esterification kettle 3 reheats the primary esterified product flowing out of the first esterification kettle 2 to carry out esterification to obtain a secondary esterified product;

[0039] The titanium dioxide preparation system 4 prepares a titanium dioxide EG solution and pumps the titanium dioxide EG solution into the slurry preparation kettle 1, the first esterification kettle 2, and the second esterification kettle 3 through a titanium dioxide transfer pump;

[0040] The first precondensation kettle 5 carries out a pre-polycondensation reaction on the secondary esterified product flowing out of the second esterification kettle 3 to obtain a primary precondensate;

[0041] The second precondensation kettle 6 carries out a pre-polycondensation reaction on the primary precondensate flowing out of the first precondensation kettle 5 again to obtain a secondary precondensate;

[0042] The final condensation kettle 7 carries out a polycondensation reaction on the secondary precondensate flowing out of the second precondensation kettle 6 to obtain a PETG melt;

[0043] The pelletizer 8 granulates the PETG melt to obtain copolyester white chips for PETG heat-shrinkable white film.

[0044] Both the first esterification kettle 2 and the second esterification kettle 3 are connected to the same process tower 17. EG and water in the first esterification kettle 2 and the second esterification kettle 3 are separated through the process tower 17. The separated EG flows into the first esterification kettle 2 and the second esterification kettle 3 to continue the reaction, and the separated wastewater flows into the stripping tower 18 for treatment.

[0045] The first precondensation kettle 5, the second precondensation kettle 6, and the final condensation kettle 7 are respectively connected to their own scraper condensers 9. EG, water vapor, and oligomers in the first precondensation kettle 5, the second precondensation kettle 6, and the final condensation kettle 7 flow into the scraper condenser 9.

[0046] Three scraper condensers 9 are all connected to the same vacuum ejector pump 10, and the non-condensable gases of the scraper condensers 9 flow into the vacuum ejector pump 10. The vacuum ejector pump 10 is connected to an EG evaporator 11 and a liquid ring vacuum pump 12, and the liquid ring vacuum pump 13 is connected to a scrubbing tower 13. The non-condensable gases in the polycondensation system are extracted through the vacuum ejector pump 10 and the liquid ring vacuum pump 12. The EG evaporator 11 generates the motive steam for the vacuum system, and the steam generates vacuum through three-stage injection and spraying to extract the small molecule gases in the first pre-condensation kettle 5, the second pre-condensation kettle 6 and the final condensation kettle 7.

[0047] Among them, the titanium dioxide preparation system 4 is as Figure 2 shown, and includes a preparation tank 14, a finished product tank 15, a finished product transfer pump 16, and a finished product filter 17. Titanium dioxide and an EG solution are stirred in the preparation tank 14 to form a primary titanium dioxide EG solution material, and the primary titanium dioxide EG solution material flows into the finished product tank 15 and then passes through the finished product filter 17 through the finished product transfer pump 16 to obtain a titanium dioxide EG solution.

[0048] The viscosity of the produced PETG white slices is 0.64 (dl / g), and the titanium dioxide content is 18 wt%.

[0049] The above are only specific embodiments of the present invention, but the technical features of the present invention are not limited thereto. Any simple changes, equivalent replacements or modifications made based on the present invention to solve basically the same technical problems and achieve basically the same technical effects are all covered by the protection scope of the present invention.

Claims

1. The copolyester white chip production system for PETG heat-shrinkable white film is characterized in that: including a slurry preparation kettle for mixing a catalyst, a titanium dioxide EG solution, CHDM, PTA, and EG according to a ratio to form a slurry; an esterification system for heating and esterifying the slurry fed from the slurry preparation kettle to obtain an esterified product; a titanium dioxide preparation system for preparing the titanium dioxide EG solution and flowing the titanium dioxide EG solution into the slurry preparation kettle and the esterification system; a pre-condensation system for subjecting the esterified product flowing out of the esterification system to a polycondensation reaction to obtain a PETG melt; a pelletizer for pelletizing the PETG melt to obtain a copolyester white slice for PETG heat-shrinkable white film.

2. The copolyester white chip production system for PETG heat-shrinkable white film according to claim 1, wherein: The esterification system includes a first esterification kettle for heating the slurry fed from the slurry preparation kettle to carry out an esterification reaction to obtain a primary esterified product; a second esterification kettle for reheating the primary esterified product flowing out of the first esterification kettle to carry out esterification to obtain a secondary esterified product.

3. The copolyester white chip production system for PETG heat-shrinkable white film according to claim 2, wherein: Both the first esterification kettle and the second esterification kettle are connected to the same process tower, and the process tower is connected to a stripping tower.

4. The copolyester white chip production system for PETG heat-shrinkable white film according to claim 1, wherein: The pre-condensation system includes a first pre-condensation kettle for subjecting the esterified product flowing out of the esterification system to a pre-polycondensation reaction to obtain a primary pre-condensed product; a second pre-condensation kettle for subjecting the primary pre-condensed product flowing out of the first pre-condensation kettle to a pre-polycondensation reaction again to obtain a secondary pre-condensed product; a final condensation kettle for subjecting the secondary pre-condensed product flowing out of the second pre-condensation kettle to a polycondensation reaction to obtain a PETG melt.

5. The copolyester white chip production system for PETG heat-shrinkable white film according to claim 4, wherein: The first pre-condensation kettle, the second pre-condensation kettle, and the final condensation kettle are respectively connected to their own scraper condensers. The three scraper condensers are all connected to the same vacuum ejector pump. The vacuum ejector pump is connected to an EG evaporator and a scrubbing tower. A liquid ring vacuum pump is connected between the scrubbing tower and the vacuum ejector pump.

6. The copolyester white chip production system for PETG heat-shrinkable white film according to claim 1, wherein: The titanium dioxide preparation system includes a preparation tank, a finished product tank, a finished product transfer pump, and a finished product filter. Titanium dioxide and an EG solution are stirred in the preparation tank to form a titanium dioxide EG solution raw material. The titanium dioxide EG solution raw material flows into the finished product tank and is prepared into the titanium dioxide EG solution through the finished product transfer pump and the finished product filter.

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