KR102163351B1 - Manufacturing method of recycled PET chip for manufacturing high strength polyester long fiber - Google Patents

Abstract

The present invention relates to a method for producing a high intrinsic viscosity (IV) and high purity recycled PET chip suitable as a raw material of a high strength polyester long fiber. According to the present invention, low-grade used PET with intrinsic viscosity (IV) of 0.72 dl/g is collected, and only a transparent PET flake is sorted from a PET flake pulverized into 3-5 mm and then crystalized. Then, a solid polymer obtained by a one-step solid polymerization is melted, extruded, and cut, and thus a recycled PET chip having an intrinsic viscosity (IV) of 1.02-1.05 dl/g is produced. According to the present invention, a high-class PET flake is recycled from low-class used PET, and thus a product having a high added value can be produced. Accordingly, together with the industrial effect enhancing recycling usage rates, an effect in industrial advantage is ensured.

Description

Manufacturing method of recycled PET chip for manufacturing high strength polyester long fiber {Manufacturing method of recycled PET chip for manufacturing high strength polyester long fiber}

The present invention relates to a method for manufacturing recycled PET chips for manufacturing high-strength polyester long fibers, and specifically, high intrinsic properties suitable as a raw material for high-strength polyester long fibers by utilizing recycled PET bottle flakes having a low intrinsic viscosity (IV). The present invention relates to a method of manufacturing a recycled polyethylene terephthalate chip with viscosity (IV) and high purity.

Polyethylene terephthalate (PET) has excellent physical and chemical properties and is used in various applications such as textiles, films, tire cords, and beverage containers. In particular, it is advantageous along with the growth of the beverage market such as carbonated beverages, mineral water, and juice beverages. As the demand for bottles, which is a substitute for containers and hazardous plastic containers, is steadily increasing, these PET bottles are treated as household waste unless they are used for other purposes after use, and if not properly disposed of, they remain pollutants. do.

PET bottle flakes from currently used PET bottles are used for recycling, but recycled PET bottle flakes have low intrinsic viscosity (IV) (0.72dl/g) and low purity, mainly polyester short fiber, packaging material PET. Since it is used as a low-value-added product such as sheet, there is a limit to regeneration. Therefore, research and development to increase the rate of regeneration by regenerating it into a product with higher added value using recycled PET bottle flakes is required.

For example, in relation to the recycling and use of the used PET bottle, the pulverized PET bottle is added to water to separate the pulverized PET bottle from the caps or cap retainers having different specific gravity, labels, and components of the bottom of the empty bottle. The step of obtaining, adding the separated PET pulverized product to white kerosene or diesel and stirring while heating to remove the label and labeling adhesive component contained in the pulverized PET, and the pulverized PET from which the label and the adhesive component for labeling have been removed Disclosing a method for recovering and recycling PET from a PET empty bottle consisting of removing residual solvent attached to the pulverized PET during stirring by adding normal hexane, Patent Document 2 discloses an input step of introducing a compressed PET bottle, and the input A sorting step in which the PET bottle compressed and inputted in the step is dismantled, and the foreign matter attached to the PET bottle is separated by color of the PET bottle, and the crushing step in which PET chips are formed by grinding to a certain size after sorting is completed in the sorting step. Step and washing step of removing foreign substances, label bonds, and chemicals using cold water and hot water from the PET chips crushed in the crushing step, and drying to remove moisture and foreign substances remaining on the PET chips washed in the washing step And a dust collecting unit that collects and removes pollutants generated in the sorting step, crushing step, washing step, and drying step, but the prior art discloses a method for simply selecting used PET bottles. It is only a technology of the degree, and there is no implication about the technology of recycling into a product with higher added value using recycled PET bottle flakes.

In addition, the step of forming polyester flakes by wet grinding and drying the polyester bottle body subjected to the pretreatment process in Patent Document 3; First sorting the polyester flakes by wind power and specific gravity difference; Forming a polyester powder by wet grinding and drying the first selected polyester flakes; Secondary screening of the polyester powder by wind power and specific gravity difference; And melting the second-selected polyester powder to form a pellet. However, the prior art also uses conventional recycled PET bottle flakes to form short polyester fibers. It is a skill that reproduces.

In addition, in Patent Document 4, the intrinsic viscosity (IV) is high as 0.95 dl/g, and the distribution range is mainly 0.60 to 0.80 dl/g, collecting a wide PET material, mixing the collected material and making it virtually a number of non-uniform flakes. Reforming into a heterogeneous IV material mixture including mold and chunk-like fragments, and direct solid state polymerization (SSP) of the heterogeneous mixture to form a heterogeneous material having an average IV of 0.90 dl/g or more, The manufacturing method of PET material suitable for use in the manufacture of high-performance plastic straps manufactures high-performance PET straps from recycled PET bottle flakes having a somewhat high intrinsic viscosity (IV).

The inventor of the present application is a recycling technology for recycled PET bottle flakes, which has higher added value compared to the existing recycling technology, and is a high-strength polyester yarn raw material of high value added value from recycled PET bottle flakes with a low intrinsic viscosity (IV) and low purity. The present invention was completed by developing a method of manufacturing a recycled PET chip with high intrinsic viscosity (IV) and high purity suitable for use.

Patent Document 1: Korean Registered Patent Publication No. 10-0578766 Patent Document 2: Korean Registered Patent Publication No. 10-0895529 Patent Document 3: Korean Patent Application Publication No. 10-2011-0075097 Patent Document 4: Korean Registered Patent Publication No. 10-0257284

The problem to be solved in the present invention relates to the provision of a method for manufacturing recycled PET chips for manufacturing high-strength polyester long fibers, which are products with high added value, using recycled PET bottle flakes.

More specifically, recycled PET bottle flakes with low intrinsic viscosity (IV) (0.72 dl/g) are used to make high intrinsic viscosity (IV) and high-purity recycled polyethylene terephthalate (PET) chips suitable as raw materials for high-strength polyester long fibers. chip) to provide a manufacturing method.

As a solution to the problem according to the present invention, the method of manufacturing recycled PET chips for producing high-strength polyester filaments collects and pulverizes used PET of low quality with an intrinsic viscosity (IV) of 0.72dl/g. After selecting and crystallizing only transparent PET flakes from PET flakes, the solid polymer obtained by one-step solid phase polymerization is melt-extruded and cut to produce recycled PET chips with an intrinsic viscosity (IV) of 1.02 to 1.05 dl/g. It consists of including the process of.

As a solution to the problem according to the present invention, one embodiment collects low-grade used PET with an intrinsic viscosity (IV) of 0.72 dl/g, selects only transparent PET flakes from PET flakes crushed to 3 to 5 mm, and then crystallizes Then, the solid-phase polymer obtained by the one-step solid-phase polymerization reaction is melt-extruded at a melting temperature of 280°C and a vacuum of less than 5 mbar, and the molten PET polymer is physically removed by a 20 micron mesh filter. It consists of manufacturing recycled PET chips having an intrinsic viscosity (IV) of 1.02 to 1.05 dl/g by removing and cutting.

Another embodiment of a method for manufacturing recycled PET chips for manufacturing high-strength polyester long fibers as a solution to the problem according to the present invention is a). A pulverization step of pulverizing used PET of low grade with an intrinsic viscosity (IV) of 0.72 dl/g to obtain 3 to 5 mm PET flakes, b). Transparent flake sorting step of sorting transparent PET flakes from the pulverized PET flakes of the pulverizing step by an optical flake sorting machine, c). Crystallization step of crystallizing the transparent PET flakes selected in the sorting step by heating at 140°C, d). Preheating process of preheating, drying and filtering crystallized transparent PET flakes in the crystallization process with hot air, e). After solid-phase polymerization of the crystallized transparent PET flakes obtained in the preheating process under a vacuum and nitrogen atmosphere of 200 to 210° C., less than 5 mbar, and a solid phase polymerization step of staying for 5 to 6 hours under stirring, and f). The solid phase polymer of the solid phase polymerization process is melt-extruded at a melting temperature of 280°C and a vacuum of less than 5 mbar, and the PET polymer in the molten state is physically removed and cut to remove foreign substances contained in the polymer with a 20 micron mesh filter. ) Is made of a recycled PET chip manufacturing process of 1.02 ~ 1.05dl/g of recycled PET chips.

In the method for manufacturing recycled PET chips for manufacturing high-strength polyester filaments according to the present invention, the reaction time is reduced by about 4 times compared to the solid-phase polymerization in the form of chips by solid-phase polymerization of flakes crushed into 3mm to 5mm. There is a characteristic that it is possible to obtain a product of uniform quality by reducing the deviation of the intrinsic viscosity (IV) that occurs during solid phase polymerization due to the difference of particles by removing particles of less than 1mm during the preheating process.

In addition, recycled PET chips with high intrinsic viscosity (IV) (1.02 ~ 1.05dl/g) from used PET with low intrinsic viscosity (IV) (0.72dl/g) are manufactured and applied as a raw material for high-strength polyester filament. As a result, it is regenerated as a high value-added product and has not only a very advantageous effect commercially, but also has the advantage of increasing the recycling rate.

1 is a view schematically showing a process of manufacturing recycled PET chips for manufacturing high-strength polyester long fibers according to the present invention

Hereinafter, in order to practice the present invention, it will be described in more detail, but the present invention is not limited by the following description.

[Fig. 1] is a diagram schematically showing a process of manufacturing a recycled PET chip for manufacturing a high strength polyester long fiber according to the present invention, and with reference to FIG. 1, a recycled PET for manufacturing a high strength polyester long fiber according to the present invention A method of manufacturing a chip will be described.

A method of manufacturing a recycled PET chip for manufacturing a high-strength polyester long fiber according to the present invention is a). A pulverization step of pulverizing used PET of low grade with an intrinsic viscosity (IV) of 0.72 dl/g to obtain 3 to 5 mm PET flakes, b). Transparent flake sorting step of sorting transparent PET flakes from the pulverized PET flakes of the pulverizing step by an optical flake sorting machine, c). Crystallization step of crystallizing the transparent PET flakes selected in the sorting step by heating at 140°C, d). Preheating process of preheating, drying and filtering crystallized transparent PET flakes in the crystallization process with hot air, e). After solid-phase polymerization of the crystallized transparent PET flakes obtained in the preheating process under a vacuum and nitrogen atmosphere of 200 to 210° C., less than 5 mbar, and a solid phase polymerization step of staying for 5 to 6 hours under stirring, and f). It consists of a process for manufacturing recycled PET chips by melt-extruding and cutting the solid-phase polymerization product of the solid-phase polymerization process to produce recycled PET chips.

A) according to the invention. The pulverization process is a process of pulverizing used PET of 0.72 dl/g into 3 to 5 mm to obtain PET flakes. The finer the PET flakes, the higher the specific surface area, so the reaction speed of solid phase polymerization can be improved even at the same temperature. .

In the pulverization process of the present invention, the PET used to improve the reaction rate of the solid phase polymerization is pulverized into 3 to 5 mm PET flakes, and the 3 to 5 mm fine PET flakes have a high specific surface area to increase the reaction speed of the solid phase polymerization. There is an effect of improving.

PET flakes of 3 to 5 mm fine particles according to the present invention have an improved reaction speed of solid phase polymerization compared to PET flakes of 8 to 16 mm, and the reaction time is reduced by 4 times compared to the chip type, which is very advantageous in terms of energy. There is a side surface, and in order to reduce the deviation of the intrinsic viscosity (IV) generated during solid phase polymerization, a PET flake of a uniform size of 3 mm is preferable.

B) according to the invention. The transparent flake sorting process is a process to increase the purity by sorting only transparent PET flakes from the pulverized PET flakes using an optical flake sorting machine, and the optical flake sorting machine employs a NIR CCD camera to sort out only transparent PET flakes, resulting in high purity recycled PET chips. It is possible to manufacture.

C) according to the invention. The crystallization process consists of a process of crystallizing by preheating and drying for about 2.5 hours while heating the raw material transparent PET flakes at 140° C. under stirring in the crystallizer 1, as shown in FIG. 1.

In the crystallization process of the present invention, it is possible to prevent sticking in the reactor during the solid-phase polymerization reaction by crystallization of transparent PET flakes, and after preheating for the solid-phase polymerization reaction simply without a separate crystallization process according to the present invention When the polymerization reaction is carried out, the fixing of raw materials may occur in the reactor, which adversely affects the efficiency of the solid phase polymerization reaction.

D) according to the invention. The preheating process is a process of preheating, drying and filtering the transparent PET flakes crystallized in the preheater 2 for the polymerization reaction as shown in [Fig. 1] with hot air at 220°C.

In the preheating process of the present invention, PET flakes crystallized by using hot air at 220° C. are preheated and dried for solid phase polymerization, and fine PET flakes of less than 1 mm, which adversely affect the solid phase polymerization reaction, are transferred to the outside of the preheater with hot air. It consists of a process of exhausting and filtering.

By filtering the fine PET flakes of less than 1 mm in the preheating process of the present invention, it is possible to reduce the variation of the intrinsic viscosity (IV) in the solid phase polymerization reaction, thereby obtaining a product of uniform quality.

E) according to the invention. In the solid phase polymerization process, while maintaining the crystallized transparent PET flakes at 200 ~ 210 ℃ in the reactor 3 as shown in [Fig. 1], a vacuum of less than 5 mbar and nitrogen are introduced into the reactor at a flow rate of 2000 L/hr while nitrogen It consists of solid-phase polymerization in one-step under an atmosphere.

The reaction temperature in the solid-phase polymerization process of the present invention is preferably maintained at 200 to 210°C. At a high temperature of about 240°C, the possibility of yellowing of PET flakes is high, which is not desirable.

And when the solid-phase polymerization reaction is completed, the reaction product is held in the lower part of the reactor 3 under stirring for 5 to 6 hours, and the reaction product is allowed to stay for 5 to 6 hours under agitation after the solid-phase polymerization reaction is completed. It prevents bridging of flakes to facilitate the discharge of PET flakes.

PET flakes discharged after completion of the solid phase polymerization process of the present invention are stored in the hopper 4 as shown in [Fig. 1], and PET flakes with an intrinsic viscosity (IV) of 1.02 to 1.05 dl/g It is discharged from the reactor (3).

F) according to the invention. The recycled PET chip manufacturing process is melt-extruded and cut using the chip manufacturing apparatus 5 as shown in [Fig. 1] to use the solid-phase polymerization reactant to be used as a raw material for high-strength polyester filaments. It is a manufacturing process.

The chip manufacturing apparatus employed in the recycled PET chip manufacturing process of the present invention is melt-extruded in a vacuum state of less than 5 mbar and a melting temperature of 280°C in an extruder as shown in [Fig. 1]. The PET polymer physically removes foreign substances contained in the polymer with a 20 micron mesh filter, thereby making it possible to produce products of higher purity.

In addition, the chip manufacturing apparatus of the present invention is manufactured into chips by cutting with an underwater cutting method at a rotational speed of 3000 RPM, and the cut recycled PET chips are crystallized by residual heat and finally used as a raw material for high-strength polyester filaments. Suitable recycled PET chips are produced.

As described above, the recycled PET chip manufacturing method for producing high-strength polyester long fibers according to the present invention has a low intrinsic viscosity (IV) (0.72 dl/g) from a low-grade used PET with a high intrinsic viscosity (IV) ( 1.02 ~ 1.05dl/g) It can be seen that it is an industrially advantageous invention because it can produce products such as high-strength polyester long fibers with high added value by manufacturing recycled PET chips.

In addition, the method of manufacturing recycled PET chips for manufacturing high-strength polyester filaments according to the present invention improves the speed of the solid phase polymerization reaction by pulverizing used PET into 3 to 5 mm PET flakes, and employs a crystallization process. An inventor who improves the efficiency of solid phase polymerization reaction and improves the recyclability of used PET by adopting a filtering process by hot air in the preheating process to make the product quality uniform, and also improves the technology to recycle the used PET flakes. Can be seen.

Claims (6)

a). A pulverization process of pulverizing used PET of low grade with an intrinsic viscosity (IV) of 0.72 dl/g to obtain 3 to 5 mm PET flakes,
b). A transparent flake sorting process for sorting transparent PET flakes from the pulverized PET flakes of the grinding process by an optical flake sorter,
c). Crystallization process of crystallizing the transparent PET flakes selected in the screening process by heating at 140°C
d). Preheating process of preheating, drying and filtering crystallized transparent PET flakes in the crystallization process with hot air,
e). The solid-phase polymerization process of solid-phase polymerization of the crystallized transparent PET flakes obtained in the preheating process under a vacuum and nitrogen atmosphere of 200 to 210° C., less than 5 mbar, and then staying for 5 to 6 hours under stirring, and
f). High-strength polyester filament manufacturing, characterized in that it includes a process of manufacturing recycled PET chips having an intrinsic viscosity (IV) of 1.02 to 1.05 dl/g by melt-extruding and cutting the solid-phase polymerization product of the solid-state polymerization process. Recycled PET chip manufacturing method for. The method of claim 1, wherein the sorting process uses a NIR CCD camera as an optical flake sorter to sort only transparent PET flakes. The method of claim 2, wherein in the crystallization process, the selected transparent PET flakes are crystallized while maintaining the selected transparent PET flakes at 140° C. for 2.5 hours. The method of claim 3, wherein the preheating process comprises preheating and drying the crystallized transparent PET flakes with hot air, and filtering PET flakes of less than 1 mm. The method of claim 4, wherein the nitrogen atmosphere in the preheating process is solid-phase polymerization under a flow rate of nitrogen 2000ℓ/hr. The method of claim 5, wherein the recycled PET chip manufacturing process is melt-extruded at a melting temperature of 280°C and a vacuum of less than 5 mbar, and after physically removing foreign substances contained in the polymer with a 20 micron mesh filter, the molten PET polymer is A method of manufacturing recycled PET chips for manufacturing high-strength polyester filaments, characterized in that cutting by underwater cutting at a rotational speed to produce chips.

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