HK1209145B - Preparation method of polycyclohexylenedimethylene terephthalate resin having excellent color, and polycyclohexylenedimethylene terephthalate resin prepared by the same - Google Patents

Abstract

A method for producing polycyclohexylenedimethylene terephthalate resin according to the present invention comprises the steps of: putting a titanium compound and a germanium compound as a catalyst into a mixture of a diol compound and a dicarboxylic acid; and stirring the mixture to perform esterification and polycondensation, wherein the titanium compound is put into the mixture for the content of titanium to be 20 ppm or less based on the weight of the final polycyclohexylenedimethylene terephthalate resin. The method for producing polycyclohexylenedimethylene terephthalate resin can produce polycyclohexylenedimethylene terephthalate resin which is excellently polymerized, has an excellent coloring and light reflection rate, and dramatically improved thermal stability, and the polycyclohexylenedimethylene terephthalate resin produced by the present invention is suitable for a LED housing material.

Description

Method for producing polycyclohexylenedimethylene terephthalate resin having excellent coloring property and polycyclohexylenedimethylene terephthalate resin produced thereby

Technical Field

The present invention relates to a method for preparing polycyclohexylenedimethylene terephthalate resin and polycyclohexylenedimethylene terephthalate resin prepared by the same. More particularly, the present invention relates to a method for preparing a polycyclohexylenedimethylene terephthalate resin having excellent color and a polycyclohexylenedimethylene terephthalate resin prepared by the preparation method.

Background

Poly (alkylene terephthalate) has excellent physical properties such as abrasion resistance, durability, thermal stability, etc., and thus has been used as a material for manufacturing fibers, films, and molded products. Poly (ethylene terephthalate) (hereinafter, referred to as 'PET'), poly (butylene terephthalate) (hereinafter, referred to as 'PBT'), and poly (cyclohexylenedimethylene terephthalate) (poly (1, 4-cyclohexanedimethylene terephthalate), hereinafter, referred to as 'PCT') are commercial polyalkylene terephthalates. Among the most widely used commercial materials are PET, which is mainly used for fibers, bottles, or the like.

Despite its excellent physical properties, PET requires a nucleating agent and a crystallization accelerator as processing aids when used as an engineering plastic required to have high crystallinity, and during the injection molding process, the production rate becomes low or the molding temperature must be controlled to maintain a high crystallization rate because it has a relatively low crystallization rate.

Meanwhile, since PBT has a higher crystallization rate than PET, it overcomes the above-mentioned problem in physical properties of PET for engineering plastics, i.e., a low crystallization rate, and thus has been widely used for engineering plastics. However, PBT has a lower heat deflection temperature (heat deflection temperature) than PET, and thus its use in applications requiring high heat resistance has been limited despite its excellent moldability (moldability) compared to PET.

Meanwhile, PCT has attracted much attention as a new material capable of overcoming the above-mentioned problems of polyester materials (i.e., moldability problems due to a slow crystallization rate and application limited due to a low heat distortion temperature).

This PCT is a crystalline polyester prepared by esterification or transesterification and polycondensation of terephthalic acid (hereinafter, referred to as TPA) or dimethyl terephthalate (hereinafter, referred to as DMT) and 1, 4-cyclohexanedimethanol (hereinafter, referred to as CHDM), and has a very high melting point (Tm) and a very fast crystallization rate. Since the first development in 1960, PCT has been mainly applied to carpets because of the soft touch of PCT fibers. However, with the advent of polyamides, the usefulness of PCT has gradually declined. Since the development of PCT compound formulations in the engineering plastics field in the 80 s of the 20 th century, they have only been applied to connectors and heat-resistant parts in the electrical, electronic and automotive fields, which require high heat resistance.

PCT has excellent heat resistance, chemical resistance, moisture resistance and flowability compared to widely used polyesters, PET and PBT. In particular, PCT has a heat distortion temperature of 245 ℃ to 260 ℃ and a continuous use temperature of 130 ℃ to 150 ℃. Thus, among the commercial non-complete aromatic polyesters (excluding liquid crystalline polyesters), PCT is the only engineering plastic belonging to the super engineering plastics (e.g., polyamides, polyphenylene sulfides, and liquid crystalline polymers) as an alternative to metals. In particular, PCT has very excellent color stability and remarkably low water absorption rate compared to other polymer resins such as polyamide or the like, and thus, it can be effectively applied to electronic materials produced by high-temperature surface mounting technology or housings or reflectors of LEDs (light emitting diodes) that are continuously exposed to heat and light during use of products.

U.S. Pat. No. 5,106,944 discloses a process for preparing PCT using DMT and CHDM as the primary materials and titanium alkoxides and alkaline earth metal salts as catalysts, and U.S. Pat. No. 5,124,388 discloses a technique for improving the color of PCT copolyesters and PCT copolyester/polycarbonate blends by using hindered phenol stabilizers. However, in these patents, germanium compounds are not used as catalysts.

Further, U.S. Pat. No. 5,596,068 discloses a polyester resin for producing thick-walled bottles having high transparency and neutral color by using an antimony compound, a germanium compound, and a phosphorus compound. However, this patent is characterized by including 0.5 to 15% by weight of CHDM and the resin has a large difference from PCT resin. In particular, no mention is made of a significant improvement in its color and light reflectance by using a germanium catalyst.

U.S. Pat. No. 4,972,015 discloses a thin-walled thermoformed thermoset article prepared by using PCT and PCT copolyester having an intrinsic viscosity of 0.7 to 1.1, and U.S. Pat. No. 5,242,967 discloses a method for improving the crystallization characteristics of PCT by adding aliphatic polyester. Further, U.S. patent No. 4,859,732 discloses a formulation of PCT compound with the addition of linear alcohol and glass reinforcing fibers to improve the crystallization characteristics and strength of PCT.

However, the conventional art only proposes a composition for improving crystalline characteristics and color in a mixing step, and there has been no report on a preparation method capable of substantially improving color stability and thermal stability of PCT in a PCT polymerization step.

BRIEF SUMMARY OF THE PRESENT DISCLOSURE

[ problem ] to

The present invention provides a method for preparing a polycyclohexylenedimethylene terephthalate resin having excellent color and improved thermal stability.

[ technical solution ]

According to one aspect of the present invention, a method for preparing a polycyclohexylenedimethylene terephthalate resin comprises the steps of: injecting a titanium compound and a germanium compound as a catalyst into a mixture of a diol compound and a dicarboxylic acid under stirring; and performing esterification reaction and polycondensation reaction, and the titanium compound is injected in a titanium atom content of 20ppm or less based on the weight of the final polycyclohexyldimethylene terephthalate resin.

Further, the germanium compound is injected in a germanium atom content of 30ppm to 1,000ppm based on the weight of the final polycyclohexylenedimethylene terephthalate resin.

Hereinbefore, the diol compound may comprise Cyclohexanedimethanol (CHDM).

Herein, the diol compound may further include one or more selected from the group consisting of: ethylene glycol, diethylene glycol, 1, 4-butanediol, 1, 3-propanediol and neopentyl glycol.

In the above, the dicarboxylic acid may comprise terephthalic acid (TPA) or dimethyl terephthalic acid (DMT).

Herein, the dicarboxylic acid may further include one or more selected from the group consisting of: isophthalic acid (IPA), naphthalene 2, 6-dicarboxylic acid (2,6-NDA), dimethylisophthalic acid (DMI), and dimethylnaphthalene 2, 6-dicarboxylic acid (2, 6-NDC).

Further, the titanium compound may be selected from the group consisting of: titanium oxide, titanium chelate, tetra-n-propyl titanate, tetra-isopropyl titanate, tetra-n-butyl titanate, tetra-isobutyl titanate, and butyl isopropyl titanate.

Further, the germanium compound may be germanium dioxide.

In addition, the preparation method may further include the step of injecting a phosphorus-based stabilizer.

Herein, the phosphorus-based stabilizer may be selected from the group consisting of: triethyl phosphate, trimethyl phosphate, triphenyl phosphate, triethyl phosphonoacetate (tri-ethyl phosphonoacetate), phosphoric acid and phosphorous acid.

According to another aspect of the present invention, the polycyclohexylenedimethylene terephthalate resin may have an intrinsic viscosity of 1.10dl/g or less and a color L value of 87 or more and a color b value of 4 or less after heat-treating at 150 ℃ for 1 hour.

According to another aspect of the present invention, the polycyclohexylenedimethylene terephthalate resin has a titanium atom content of 20ppm or less based on the weight of the final polycyclohexylenedimethylene terephthalate resin.

Hereinbefore, the germanium compound may also be contained in a germanium atom content of 30ppm to 1,000ppm based on the weight of the final polycyclohexylenedimethylene terephthalate resin.

Further, the phosphorus compound may also be contained in a phosphorus atom content of 30ppm to 1,000ppm based on the weight of the final polycyclohexyldimethylene terephthalate resin.

[ advantageous effects ]

The method for preparing a polycyclohexylenedimethylene terephthalate resin according to the present invention can be used to prepare a polycyclohexylenedimethylene terephthalate resin having excellent polymerization degree, color and light reflection coefficient and having significantly improved thermal stability, and it is appropriate to use the polycyclohexylenedimethylene terephthalate resin according to the present invention as an LED housing material.

[ best mode ]

The present invention may be variously modified and may have a plurality of embodiments. Specific embodiments of the present invention will be described in detail in the detailed description. However, the invention is not limited to the specific embodiments and it is to be understood that the invention includes any modifications, equivalents, or alternatives falling within the spirit and scope of the invention. During the description of the present invention, if it is considered that detailed description on the related disclosed technology makes the present invention unclear, it will not be presented herein.

The present invention provides a method for preparing a polycyclohexylenedimethylene terephthalate resin, comprising the steps of: injecting a titanium compound and a germanium compound as a catalyst into a mixture of a diol compound and a dicarboxylic acid under stirring; and performing esterification reaction and polycondensation reaction, wherein the titanium compound is injected in a titanium atom content of 20ppm or less based on the weight of the final polycyclohexyldimethylene terephthalate resin.

Further, the present invention provides a polycyclohexyldimethylene terephthalate resin having an intrinsic viscosity of 1.10dl/g or less and a color L value of 87 or more and a color b value of 4 or less after heat-treating at 150 ℃ for 1 hour.

Meanwhile, the present invention provides a polycyclohexylenedimethylene terephthalate resin having a titanium atom content of 20ppm or less based on the weight of the final polycyclohexylenedimethylene terephthalate resin.

Hereinafter, a method for preparing a polycyclohexylenedimethylene terephthalate resin and a polycyclohexylenedimethylene terephthalate resin will be described in more detail according to embodiments of the present invention.

Generally, the non-fully aromatic polyesters are typically polymerized from dicarboxylic acids and diol compounds according to methods known in the art. The method for preparing the aromatic polyester resin may include the steps of: (A) mixing a dicarboxylic acid compound, a diol compound, and a phosphorus-based stabilizer compound to perform an esterification reaction; (B) adding a catalyst compound to a product obtained by the esterification reaction to perform a polycondensation reaction; (C) extruding the polycondensation reaction to produce pellets (pellets); and if necessary, (D) crystallizing the pellet to perform solid-phase polymerization.

According to one embodiment of the present invention, there is provided a method for preparing a polycyclohexylenedimethylene terephthalate resin, the method comprising the steps of: injecting a titanium compound and a germanium compound as a catalyst into a mixture of a diol compound and a dicarboxylic acid under stirring; and performing esterification reaction and polycondensation reaction, wherein the titanium compound is injected in a titanium atom content of 20ppm or less based on the weight of the final polycyclohexyldimethylene terephthalate resin.

The method for preparing polycyclohexylenedimethylene terephthalate resin according to the present invention is characterized in that: a titanium compound and a germanium compound are used as a catalyst, and the titanium compound is injected in a titanium atom content of 20ppm or less based on the weight of the final polycyclohexyldimethylene terephthalate resin, and the germanium compound is injected in a germanium atom content of 30ppm to 1,000ppm based on the weight of the final polycyclohexyldimethylene terephthalate resin.

Due to the addition of germanium atoms, the color improvement effect can be more effectively achieved. If the germanium atom content is less than 30ppm, the color improvement effect is not noticeable, and if the germanium atom content is more than 1000ppm, side reactions may occur and it may remain in the polymer to increase the haze value (hazevalue).

Hereinbefore, the diol compound may include Cyclohexanedimethanol (CHDM), and may further include one or more selected from the group consisting of: ethylene glycol, diethylene glycol, 1, 4-butanediol, 1, 3-propanediol, and neopentyl glycol. That is, the diol compound is typically referred to as 1, 4-cyclohexanedimethanol, but may also include minor amounts of one or more selected from the group consisting of: ethylene glycol, diethylene glycol, 1, 4-butanediol, 1, 3-propanediol, and neopentyl glycol.

Meanwhile, the dicarboxylic acid may include terephthalic acid (TPA) or dimethyl terephthalic acid (DMT), and may further include one or more selected from the group consisting of: isophthalic acid (IPA), naphthalene 2, 6-dicarboxylic acid (2,6-NDA), dimethylisophthalic acid (DMI), and dimethylnaphthalene 2, 6-dicarboxylic acid (2, 6-NDC). That is, the dicarboxylic acid or derivative thereof to be used is generally referred to as terephthalic acid (TPA) or dimethyl terephthalic acid (DMT), but may also include a small amount of isophthalic acid (IPA), 2, 6-naphthalenedicarboxylic acid (2,6-NDA), dimethyl isophthalate (DMI), or dimethylnaphthalene 2, 6-dicarboxylic acid (2, 6-NDC).

Further, in the production method according to the present invention, it is preferable that one of terephthalic acid (TPA) and dimethyl terephthalic acid (DMT) is used as the dicarboxylic acid in an amount of 80 mol% or more based on the moles of the total acids, and it is preferable that cyclohexanedimethanol (1, 4-cyclohexanedimethanol) is used as the diol compound in an amount of 80 mol% or more based on the moles of the total diol compound. If their amount is less than the above mole%, the physical properties of the polyester become very different from those of PCT, and thus it is difficult to use the polyester in applications developed to be suitable for the crystallized PCT resin.

In the present invention, a titanium compound is used as the catalyst, and the titanium compound may be selected from the group consisting of: titanium oxide, titanium chelate, tetra-n-propyl titanate, tetra-isopropyl titanate, tetra-n-butyl titanate, tetra-isobutyl titanate, and butyl isopropyl titanate.

Further, the titanium compound may be injected in a titanium atom content of 20ppm or less based on the weight of the final polycyclohexylenedimethylene terephthalate resin. The content is limited to the above range because excessive titanium content may cause side reactions, deteriorated color, and greatly reduce molecular weight during processing.

The germanium compound may be germanium dioxide, and the germanium compound may be injected with a germanium atom content of 30ppm to 1,000ppm based on the weight of the final polycyclohexyldimethylene terephthalate resin. If the content is less than 30ppm, the color-improving effect is not noticeable, and if the content is more than 1000ppm, side reactions may occur and it may remain in the polymer to increase the haze value.

Further, a phosphorus-based stabilizer may also be added to the mixture of the diol compound and the dicarboxylic acid. Such a phosphorus-based stabilizer is preferably injected during the initial stage of the esterification reaction, and more preferably before the esterification reaction. Preferably, the stabilizer is injected within a phosphorus atom content of 30ppm based on the weight of the final polycyclohexyldimethylene terephthalate resin. If the content of the phosphorus-based stabilizer is more than 30ppm, there are problems in that the color of the polymer is deteriorated and the catalyst activity is reduced to increase the reaction time and the polymerization degree.

Herein, the phosphorus-based stabilizer may be selected from the group consisting of: triethyl phosphate, trimethyl phosphate, triphenyl phosphate, triethyl phosphonoacetate, phosphoric acid and phosphorous acid.

Further, in the present invention, the esterification reaction can be carried out under similar reaction conditions in equipment known in the art, and preferably at a temperature of 230 to 290 ℃ and 0.0 to 3.0kg/cm²Is carried out for 4 to 10 hours under pressure. Further, it is preferred that the system is configured to remove water immediately during the esterification reaction.

Meanwhile, the polycondensation reaction may be carried out at a temperature of 290 to 320 ℃ and a pressure of 0.1 to 2.0 torr for 100 minutes to 300 minutes. Preferably, the system is configured to immediately remove the cyclohexanedimethanol and the by-products generated during the polycondensation reaction.

The solid phase reaction can be carried out at a temperature of 230 to 270 ℃ under a vacuum of 0.2 to 2.0 torr, or under a nitrogen atmosphere.

Meanwhile, most of the polymers are colored after polymerization. In particular, when it is exposed to excessive heat for a long time during polymerization, the color of the polymer material becomes deep yellow due to a pyrolysis reaction and oxidation. Since the visual appearance (including color) of the product is important, the color of the polymeric material is an important quality factor.

According to the present invention, the PCT resin prepared according to the preparation method of the polycyclohexyldimethylene terephthalate resin may have an intrinsic viscosity of 1.10dl/g or less and a color L value of 87 or more and a color b value of 4 or less after heat treatment at 150 ℃ for 1 hour.

Meanwhile, according to another aspect of the present invention, the polycyclohexylenedimethylene terephthalate resin has a titanium atom content of 20ppm or less based on the weight of the final polycyclohexylenedimethylene terephthalate resin. If the titanium content exceeds 20ppm, side reactions may frequently occur during processing, color may deteriorate, and the molecular weight may be greatly reduced.

In addition, the polycyclohexylenedimethylene terephthalate resin may also have a germanium atom content of 30ppm to 1,000ppm based on the weight of the final polycyclohexylenedimethylene terephthalate resin. If the germanium atom content is less than 30ppm, the color-improving effect is not noticeable, and if the content is more than 1000ppm, side reactions may occur and it may remain in the polymer to increase the haze value.

MODE OF THE INVENTION

Hereinafter, preferred embodiments of the present invention will be described in detail. However, these embodiments are for illustrative purposes only, and the scope of the present invention is not intended to be limited by these embodiments.

Example 1

55Kg of 1, 4-cyclohexanedimethanol (trans 70%), 48Kg of terephthalic acid, 7g of triethyl phosphate, 10g of a titanium oxide based catalyst (trade name: Hombicast PC manufactured by Sachtleben) (effective Ti ratio: 15% in catalyst), and 11.5g of germanium dioxide were added to a reactor, and esterification reaction was performed at atmospheric pressure for 3 hours while the temperature was elevated to 280 ℃ and polyester polycondensation reaction was also performed at 300 ℃ and under vacuum of 0.5 Torr to 1 Torr for 150 minutes, thereby preparing a PCT polymer.

Example 2

55Kg of 1, 4-cyclohexanedimethanol (trans 70%), 48Kg of terephthalic acid, 7g of triethyl phosphate, 10g of a titanium oxide based catalyst (trade name: Hombicast PC manufactured by Sachtleben) (effective Ti ratio: 15% in catalyst), and 23g of germanium dioxide were added to a reactor, and esterification reaction was performed at atmospheric pressure for 3 hours while the temperature was elevated to 280 ℃ and polyester polycondensation reaction was also performed at 300 ℃ and under vacuum of 0.5 Torr to 1 Torr for 150 minutes, thereby preparing a PCT polymer.

Example 3

55Kg of 1, 4-cyclohexanedimethanol (trans 70%), 48Kg of terephthalic acid, 7g of triethyl phosphate, 10g of a titanium oxide based catalyst (trade name: Hombicast PC manufactured by Sachtleben) (effective Ti ratio: 15% in catalyst), and 46g of germanium dioxide were added to a reactor, and esterification reaction was performed at atmospheric pressure for 3 hours while the temperature was elevated to 280 ℃ and polyester polycondensation reaction was also performed at 300 ℃ and under vacuum of 0.5 Torr to 1 Torr for 150 minutes, thereby preparing a PCT polymer.

Example 4

55Kg of 1, 4-cyclohexanedimethanol (trans 70%), 48Kg of terephthalic acid, 7g of triethyl phosphate, and 15g of a titanium oxide-based catalyst (trade name: Hombicast PC manufactured by Sachtleben) (effective Ti ratio in catalyst: 15%) were added to a reactor, and esterification reaction was performed at atmospheric pressure for 3 hours while the temperature was elevated to 280 ℃, and polyester polycondensation reaction was also performed at 300 ℃ and under vacuum of 0.5 Torr to 1 Torr for 150 minutes, thereby preparing PCT polymer.

Example 5

55Kg of 1, 4-cyclohexanedimethanol (trans 70%), 48Kg of terephthalic acid, 7g of triethyl phosphate, 10g of a titanium oxide based catalyst (trade name: Hombicast PC manufactured by Sachtleben) (effective Ti ratio: 15% in catalyst), and 23g of germanium dioxide were added to the reactor, and the esterification reaction was carried out at atmospheric pressure for 3 hours while the temperature was elevated to 280 ℃ and the polyester polycondensation reaction was also carried out at 300 ℃ and under a vacuum of 0.5 Torr to 1 Torr for 150 minutes. Then, solid-phase polymerization was performed at 240 ℃, thereby preparing a PCT polymer.

Comparative example 1

55Kg of 1, 4-cyclohexanedimethanol (trans 70%), 48Kg of terephthalic acid, 7g of triethyl phosphate, and 20g of a titanium oxide-based catalyst (trade name: Hombicast PC manufactured by Sachtleben) (effective Ti ratio in catalyst: 15%) were added to a reactor, and esterification reaction was performed at atmospheric pressure for 3 hours while the temperature was elevated to 280 ℃, and polyester polycondensation reaction was also performed at 300 ℃ and under vacuum of 0.5 Torr to 1 Torr for 150 minutes, thereby preparing PCT polymer.

Comparative example 2

55Kg of 1, 4-cyclohexanedimethanol (trans 70%), 48Kg of terephthalic acid, 7g of triethyl phosphate, and 25g of a titanium oxide-based catalyst (trade name: Hombicast PC manufactured by Sachtleben) (effective Ti ratio in catalyst: 15%) were added to a reactor, and esterification reaction was performed at atmospheric pressure for 3 hours while the temperature was elevated to 280 ℃, and polyester polycondensation reaction was also performed at 300 ℃ and under vacuum of 0.5 Torr to 1 Torr for 150 minutes, thereby preparing PCT polymer.

Comparative example 3

55Kg of 1, 4-cyclohexanedimethanol (trans 70%), 48Kg of terephthalic acid, 7g of triethyl phosphate, and 40g of a titanium oxide-based catalyst (trade name: Hombicast PC manufactured by Sachtleben) (effective Ti ratio in catalyst: 15%) were added to a reactor, and esterification reaction was performed at atmospheric pressure for 3 hours while the temperature was elevated to 280 ℃, and polyester polycondensation reaction was also performed at 300 ℃ and under vacuum of 0.5 Torr to 1 Torr for 150 minutes, thereby preparing PCT polymer.

Comparative example 4

55Kg of 1, 4-cyclohexanedimethanol (trans 70%), 48Kg of terephthalic acid, 7g of triethyl phosphate, and 60g of a titanium oxide-based catalyst (trade name: Hombicast PC manufactured by Sachtleben) (effective Ti ratio in catalyst: 15%) were added to a reactor, and esterification reaction was performed at atmospheric pressure for 3 hours while the temperature was elevated to 280 ℃, and polyester polycondensation reaction was also performed at 300 ℃ and under vacuum of 0.5 Torr to 1 Torr for 150 minutes, thereby preparing PCT polymer.

Comparative example 5

55Kg of 1, 4-cyclohexanedimethanol (trans 70%), 48Kg of terephthalic acid, 7g of triethyl phosphate, 15g of a titanium oxide based catalyst (trade name: Hombicast PC manufactured by Sachtleben) (effective Ti ratio: 15% in catalyst) and 168.7g of germanium dioxide were added to a reactor, and esterification reaction was performed at atmospheric pressure for 3 hours while the temperature was elevated to 280 ℃ and polyester polycondensation reaction was also performed at 300 ℃ and under vacuum of 0.5 Torr to 1 Torr for 150 minutes, thereby preparing a PCT polymer.

Comparative example 6

55Kg of 1, 4-cyclohexanedimethanol (trans 70%), 48Kg of terephthalic acid, 7g of triethyl phosphate, 25g of a titanium oxide based catalyst (trade name: Hombicast PC manufactured by Sachtleben) (effective Ti ratio: 15% in catalyst) and 168.7g of germanium dioxide were added to a reactor, and esterification reaction was performed at atmospheric pressure for 3 hours while the temperature was elevated to 280 ℃ and polyester polycondensation reaction was also performed at 300 ℃ and under vacuum of 0.5 Torr to 1 Torr for 150 minutes, thereby preparing a PCT polymer.

Experimental example 1

The intrinsic viscosity of each PCT resin obtained in examples 1 to 5 and comparative examples 1 to 6 was measured in the following manner.

PCT resin was dissolved in o-chlorophenol at a concentration of 1.2g/dl, and then the intrinsic viscosity was measured using an Ubbelohde (Ubbelohde) viscometer. The viscometer temperature was maintained at 35 ℃. The time taken when the solvent flowed through the cross section inside the viscometer (flow-out time) was defined as t and the time taken when the solution flowed through the cross section was defined as t₀When the specific viscosity is defined as follows,

wherein the intrinsic viscosity is calculated by the following correction equation:

where A is the Huggins's constant of 0.247, and c is the concentration value of 1.2 g/dl.

Experimental example 2

The color of each PCT resin obtained in examples 1 to 5 and comparative examples 1 to 6 was measured in the following manner.

The PCT resin was subjected to crystallization in a convection oven at 150 ℃ for 1 hour, and then the color of the PCT resin was measured using a colorimeter.

The CIE LAB index was used for color measurement. The CIE LAB system is a color space coordinate system defined by the CIE based on yellow-blue and green-red opponent channels (opponent channels) recognized by humans. L represents brightness (0-100; 0 represents black, 100 represents white), a represents green-red (on a 0 basis, +: red, -green), and b represents yellow-blue (on a 0 basis, +: yellow, -blue).

The conditions and physical properties of the examples and comparative examples as described above are shown in table 1 below.

[ Table 1]

As shown in table 1, it can be seen that the method for preparing a polycyclohexylenedimethylene terephthalate resin according to the present invention is used to prepare a polycyclohexylenedimethylene terephthalate resin having excellent color and light reflection coefficient, and it is appropriate to use the polycyclohexylenedimethylene terephthalate resin according to the present invention as an LED housing material.

While specific embodiments of the invention have been described in detail, those skilled in the art will understand that this description is only of the preferred embodiment and is not to be construed as limiting the scope of the invention. Thus, the breadth of the present invention should be defined by the following claims and their equivalents.

Claims (10)

1. A method for preparing polycyclohexyldimethylene terephthalate resin, comprising the steps of: injecting a titanium compound and a germanium compound as a catalyst into a mixture of a diol compound and a dicarboxylic acid under stirring; and performing an esterification reaction and a polycondensation reaction, wherein the titanium compound is injected in a titanium atom content of 20ppm or less based on the weight of the final polycyclohexyldimethylene terephthalate resin, wherein 1, 4-cyclohexanedimethanol is used as the diol compound, wherein the polycyclohexyldimethylene terephthalate resin has a color L value of 87 or more after heat treatment at 150 ℃ for 1 hour.

2. The production method according to claim 1, wherein the germanium compound is injected with a germanium atom content of 30ppm to 1,000ppm based on the weight of the final polycyclohexyldimethylene terephthalate resin.

3. The production process according to claim 1, wherein the dicarboxylic acid comprises terephthalic acid (TPA) or dimethyl terephthalic acid (DMT).

4. The production method according to claim 3, wherein the dicarboxylic acid further comprises one or more selected from the group consisting of: isophthalic acid (IPA), naphthalene 2, 6-dicarboxylic acid (2,6-NDA), dimethylisophthalic acid (DMI), and dimethylnaphthalene 2, 6-dicarboxylic acid (2, 6-NDC).

5. The production method according to claim 1, wherein the titanium compound is selected from the group consisting of: titanium oxide, titanium chelate, tetra-n-propyl titanate, tetra-isopropyl titanate, tetra-n-butyl titanate, tetra-isobutyl titanate, and butyl isopropyl titanate.

6. The method of claim 1, wherein the germanium compound is germanium dioxide.

7. The method of claim 1, further comprising the step of injecting a phosphorus-based stabilizer.

8. The production method according to claim 7, wherein the phosphorus-based stabilizer is selected from the group consisting of: triethyl phosphate, trimethyl phosphate, triphenyl phosphate, triethyl phosphonoacetate, phosphoric acid and phosphorous acid.

9. A polycyclohexyldimethylene terephthalate resin prepared by the process of any one of claims 1 to 8, wherein the polycyclohexyldimethylene terephthalate resin has a color L value of 87 or more after heat treatment at 150 ℃ for 1 hour.

10. The polycyclohexylenedimethylene terephthalate resin according to claim 9, wherein the polycyclohexylenedimethylene terephthalate resin has an intrinsic viscosity of 1.10dl/g or less and a color b-value of 4 or less after heat treatment at 150 ℃ for 1 hour.