KR100661275B1 - Method for producing industrial polyethylene naphthalate - Google Patents

Abstract

The present invention, in the production of polyethylene naphthalate by transesterification and polycondensation reaction of naphthalene dicarboxylate (NDC) and diol, using a transesterification catalyst of 30 ~ 100ppm relative to the weight of NDC during the transesterification reaction, In case of polycondensation reaction, 100 ~ 500ppm polycondensation reaction catalyst is used, and 20 ~ 300ppm of heat stabilizer is added before polycondensation reaction and the crystallization step is carried out through two or more steps at 190 ~ 250 ° C. It relates to a method for producing a polymer.

According to the present invention, a stable and uniform polyethylene naphthalate polymer may be prepared to prepare an industrial polyethylene naphthalate fiber having excellent mechanical properties and thermal stability.

Naphthalene Dicarboxylate, Polyethylene Naphthalate Fiber

Description

Method for producing industrial polyethylene naphthalate

The present invention relates to a method for producing a high viscosity chip suitable for industrial use by solid phase polymerization with a polyethylene naphthalate polymer, and more particularly, because it has a rigid molecular chain in the main chain, high melt viscosity and viscosity and axial polymerization In the polyethylene naphthalate polymer, which is difficult to remove the unreacted material and gas inside the polymer during the reaction and causes fusion during the solid phase polymerization, in order to compensate for this, the catalyst content in the melt polymerization step, the polycondensation reaction method, and the solid phase polymerization in the solid phase polymerization step By improving the temperature, crystallization method and the like, the present invention relates to a method for producing an industrial polyethylene naphthalate polymer having a high viscosity and uniformity.

Polyethylene terephthalate (PET) grew rapidly around the world in 1953, when it was first commercialized for textile use in the United States. Polyethylene terephthalate (PET) is used in many fields due to its good mechanical properties, heat resistance, chemical stability, and the like. In particular, polyethylene terephthalate (PET) has a great demand for textiles, biaxially oriented films, sheets, and beverage bottles.                         

Recently, such PET resins are being replaced with polyethylene naphthalate (PEN), which is required to reduce the weight, high performance, and high heat resistance.

PEN adopts a rigid structure of naphthalate ring instead of benzene ring of PET, which is very similar in structure to existing PET, but has excellent mechanical properties such as glass transition temperature, heat resistance, tensile strength and creep resistance. In addition, gas barrier properties are more than five times superior to PET, and thus, they are actively used in high strength thin film films, barrier bottles, heat-resistant containers, and the like. In particular, the properties of the PEN is suitable as a reinforcing material for belts and hoses requiring high strength, high heat resistance, chemical resistance, and the like, and can exhibit optimal physical properties for tire cords. Conventional tire cord materials include PET, nylon, rayon, and arimid-based fibers, but rayon and aramid have environmental disadvantages and high manufacturing costs, and PET and nylon have high temperature. There was a problem with strength and form stability. In contrast, PEN exhibits high strength, heat resistance, and low heat shrinkage, and is expected to replace many industrial materials, starting with the existing high performance race tire cord material.

PEN's manufacturing has a lot in common with PET manufacturing technology because its manufacturing facilities and technologies have a lot in common with PET manufacturing technology, but it is certain that it will stand out in many industries as a substitute for PET in the 2000s, but PEN's synthesis technology, physical properties, and melt polymerization It is true that the basic basic research is inferior.

Conventional techniques for producing such PEN polymers include Japanese Patent Laid-Open Nos. Hei 6-56975, Hei 6-293825, Hei 7-82465 and Hei 8-169940, U.S. Patent Nos. 5,350829, 4, 963644 and 5,294,695.

Japanese Patent Application Laid-open No. Hei 6-56975 is a polyester based on ethylene naphthalate, which has a carboxyl terminal concentration of 40 equivalents / 10 ⁶ gr or less and a diethylene glycol content of 1.3 wt% or less for producing a PEN composition. The method is described, and the polymer produced can obtain PEN films or fibers which are excellent in productivity of films and fibers and have excellent durability such as hydrolysis resistance. Japanese Patent Laid-Open Nos. Hei 6-293825 and Hei 7-82465 describe a method for producing PEN polymers having excellent transparency, thermal stability, surface flatness and curl resolution by adjusting the amount of reaction catalyst.

Japanese Patent Application Laid-Open No. Hei 8-169940 has a transesterification reaction and a polycondensation reaction of naphthalene dicarboxylate (NDC) and diol (diol) in the production of PEN, 0.1 to 0.5wt by weight of NDC during the transesterification reaction % Transesterification catalyst is used, and the polycondensation reaction is characterized by using a polycondensation reaction catalyst of 0 ~ 0.4wt% of NDC, Mn, K, Li, Ca, Mg as the transesterification catalyst At least one of Zn, Al and Cd compounds and at least one of Sb, Ge, Co, Ti, Su, Al, Pb, Mn and Ca compounds as polycondensation catalysts. This is described.

U.S. Patent No. 5,350,829 describes a method for crystallizing PEN pellets coated with alkylene carbonate at lower temperatures than uncoated PEN pellets, which reduces the occurrence of fusion during solid phase polymerization. It is said. U.S. Patent No. 4,963,644 discloses a method for solid-phase polymerization of an amorphous PEN prepolymer in an inert gas or vacuum state in a first step at 80 to 140 DEG C for 15 minutes to 10 hours and in a second step at 150 to 260 DEG C. Crystallization was performed for 1 minute to 4 hours, and in the third step, a method of preparing a high viscosity PEN polymer by performing solid phase polymerization at 240 to 260 ° C is described.

In addition, U.S. Patent No. 5,294,695 discloses a method for producing high viscosity PEN by reacting NDC and ethylene glycol (EG) in two stages. The intrinsic viscosity is adjusted to 0.4-1.0 dl / g, and the polycondensation catalyst is described using one of metal compounds such as Sb, Li, Ge, Ti, Zn, Pb, Fe, Mn, Mg, Al and Ca. .

An object of the present invention is to provide a fusion removal method for minimizing catalyst content during melt polymerization, bubbles in chips generated during conventional polymerization, and impurities generated during solid phase polymerization, and during solid phase polymerization due to PEN characteristics. .

In the present invention, in the preparation of PEN by transesterification and polycondensation reaction of NDC (Naphthalene dicarboxylate) and diol, using a transesterification catalyst of 30 ~ 100ppm relative to the weight of NDC during the transesterification reaction, The polycondensation reaction catalyst of 100-500 ppm is used, 20-300 ppm of heat stabilizers are added before a polycondensation reaction, and a crystallization step is performed through two or more steps between 190 degreeC and 250 degreeC.

In the manufacture of PEN melt polymers containing 90 mol% or more of NDC unit and having intrinsic viscosity of 0.3 to 0.6 dl / g and high viscosity chips of 0.6 dl / g or more, a crystallization step is performed to minimize fusion caused during solid phase polymerization. Unlike the existing method, it is not easy to remove unreacted materials during melt polymerization due to the two-step method and the characteristics of PEN polymer, which acts as an impurity during solid phase polymerization. At 1.5 to at least 0.3 to 1.2, the surface area of the polymer was increased to facilitate extraction of the unreacted material, thereby minimizing impurities after solid phase polymerization. In addition, the nozzle type (nozzle type) was changed from circular to elliptical to significantly remove bubbles in the chip.

Hereinafter, the present invention will be described in detail.

The thermal stabilizer was used because the melt polymerization temperature was high during the preparation of the PEN polymer. When the ratio of the esterification catalyst and the thermal stabilizer is not included in any suitable range, the color tone of the polymer due to deterioration during the solid phase polymerization is severely generated. In order to compensate for this, the ratio of the esterification catalyst and the heat stabilizer was maintained at a level of 0.7 to 2.0 and was polymerized to prevent deterioration during the solid phase polymerization. At this time, at least one of Mn, K, Li, Ca, Mg, Zn, Al, and Cd compounds was used as the esterification catalyst, and one of the formate was used as the heat stabilizer.

Due to the high viscosity of the polymer during melt polymerization, the polycondensation reaction is carried out by making the L / D (length / diameter) of the reactor at a minimum level of 0.3 to 1.2 from 1.5 to remove gas and unreacted substances generated during the polycondensation reaction. It was. As a result, the impurities generated by the aggregation of unreacted materials after the solid state polymerization were reduced from more than 500 ppm to less than 200 ppm.

In addition, the viscosity of the molten polymer is high, the gas generated during the axial polymerization reaction is present in the interior of the polymer when discharged, resulting in a bad spinning process. To remove this, the nozzle was changed from circular to elliptical and discharged by maintaining the soft water temperature at 20 to 100 ° C. As a result, the bubbles in the polymer can be reduced from 90% to more than 0.1%. Oval nozzle was used to produce a long axis / short axis of 1.0 ~ 3.5.

PEN polymers often cause sticking during solid phase polymerization because of their superior viscosity compared to PET. In order to compensate for the solid phase polymerization, drying was performed at 130 ° C. for at least 4 hours, primary crystallization at 200 ° C. for at least 1 hour, and secondary crystallization at 220 ° C. or higher for 2 hours. Solid phase polymerization was performed at 240 degreeC or more for 10 hours or more. As a result, the existing fusion was lowered from 10% to less than 1.0%, and the solid state polymerization time was also reduced by about 6 hours. Thus, by producing a stable and uniform PEN polymer, it is possible to produce an industrial PEN fiber having excellent mechanical properties and thermal stability.

Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited thereto.

<Example 1>

Naphthalene dicarboxylate (NDC) and ethylene glycol were mixed at a ratio of 1: 2.1, and then sufficiently dissolved at 190 ° C. or higher for at least 4 hours, and then esterification was started. In the esterification reaction, 65 ppm of Mn was used as the catalyst for the NDC weight and reacted for 3 hours from 190 ° C to 240 ° C.

For the polycondensation pre-reaction, trimester formate (TMP) was added as a thermal stabilizer to 47 ppm with respect to the NDC weight, 280 ppm of the Sb ₂ O ₃ compound was used as the polycondensation catalyst, and the reaction temperature was performed at 240 to 290 ° C. To raise the viscosity, drying was carried out at 130 ° C. for 8 hours, primary crystallization at 200 ° C. for 2 hours, secondary crystallization at 245 ° C. for 6 hours, and solid phase polymerization was carried out at 254 ° C. for 17 hours. The results are shown in Table 1 below.

Comparative Example 1

The thermal stabilizer was carried out in the same manner as in Example 1 except that 40 ppm of the NDC weight and 90 ppm of the esterification catalyst were used. The results are shown in Table 1 below.

                                Table 1

<Example 2>

The same procedure as in Example 1 was used except that the polycondensation reactor had an L / D of 1.5 to 0.5 and a nozzle having a circular to long axis / short axis ratio of 3, and the soft water temperature was maintained at 37 ° C. during discharge. It was. The results are shown in Table 2 below.

<Comparative Example 2>

L / D of the polycondensation reactor was used in the same manner as in Example 2 except that 1.5, a nozzle was used in a circular shape, and the softening temperature was maintained at 18 ° C. The results are shown in Table 2 below.

                                TABLE 2

<Example 3>

The same as in Example 1, the results are shown in Table 3.

<Comparative Example 3>

The molten polymer was dried for 8 hours at 130 ° C., precrystallized at 200 ° C. for 2 hours, and subjected to solid phase polymerization at 258 ° C. for 29 hours, and the result was as shown in Table 3 below.

                                TABLE 3

According to the present invention, it is possible to produce a stable and uniform polyethylene naphthalate polymer to produce an industrial polyethylene naphthalate fiber having excellent mechanical properties and thermal stability, as well as the L / D of the reactor during polycondensation polymerization (length / Diameter) to 1.5 to 1.2 or less in the existing 1.5 to easily extract the unreacted material to increase the surface area of the polymer to minimize the generation of impurities after the solid-phase polymerization can eliminate the inconvenience of having to clean the rollers frequently.

Claims (4)

In the process for producing polyethylene naphthalate polymer by exchanging ester and polycondensation reaction of naphthalene dicarboxylate and diol, using a transesterification catalyst of 30 to 100 ppm relative to the weight of naphthalene dicarboxylate during the transesterification reaction In case of polycondensation reaction, 100 ~ 500ppm polycondensation reaction catalyst is used, 20 ~ 300ppm thermal stabilizer is added before polycondensation reaction, and the ratio of esterification reaction catalyst and heat stabilizer is 0.7 ~ 2.0 and crystallization step is 190 ℃. Process for producing a high viscosity industrial polyethylene naphthalate polymer, characterized in that carried out in two or more steps between 250 ℃. The method for producing a high viscosity industrial polyethylene naphthalate polymer according to claim 1, wherein the polycondensation reaction has an L / D (length / diameter) of 0.3 to 1.2 in the polycondensation reaction tank. The method of producing a high viscosity industrial polyethylene naphthalate polymer according to claim 2, wherein the long axis / short axis ratio of the polymer outlet nozzle of the polycondensation reaction tank is 1.0 to 3.5 and the soft water temperature is 20 to 100 ° C. delete