KR101130262B1 - Preparation of Polyethyleneterephthalate Nanocomposite Fiber with Enhanced Modulus Retention at High Temperature - Google Patents

Abstract

The present invention relates to a poly (ethylene terephthalate) nanocomposite fiber having an excellent modulus retention and an increased glass transition temperature, and more particularly, to an amine-based polyhedral oligomeric silsesquixane (organic / inorganic hybrid nanocompound). POSS) was added at 1.0 to 3.0% by weight in the polymerization step to prepare polyethylene terephthalate nanocomposite chip having an ethylene terephthalate unit of 85 mol% or more and an intrinsic viscosity in the range of 0.50 to 1.20, and then melt spinning and PET nanocomposite fiber prepared by stretching shows an excellent modulus retention and glass transition temperature increase at high temperatures.

Modulus retention, PET nanocomposite fiber, polyhedral oligomer silsesquixane, POSS, dispersibility, glass transition temperature

Description

Preparation method of polyethylene terephthalate nanocomposite fiber with excellent modulus retention at high temperature {Preparation of Polyethyleneterephthalate Nanocomposite Fiber with Enhanced Modulus Retention at High Temperature}

The present invention relates to a poly (ethylene terephthalate) (hereinafter referred to as 'PET') nanocomposite fiber having excellent modulus retention at high temperature and an increased glass transition temperature, and specifically, a nano having excellent heat resistance at high temperature. A compound of C ₅₉ H ₁₂₇ NO ₁₂ Si ₈ which is an amine polyhedral oligomeric silsesquixane (POSS, hereinafter referred to as 'POSS'), which is a compound, is added in the polymerization step at 1.0 to 3.0 wt%. To produce a polyethylene terephthalate nanocomposite chip containing at least 85 mol% of ethylene terephthalate units and having an intrinsic viscosity in the range of 0.50 dl / g to 1.20 dl / g, followed by melt spinning and stretching the composite chip to form PET nanocomposite fibers. It relates to a method of manufacturing.

'PET', a representative polyester, was first industrialized by ICI for textiles in 1949. It grew into one of the three synthetic fibers, together with nylon and acrylic fibers, and high strength, high heat resistance, transparency and gas barrier properties in non-fiber fields. It has grown rapidly on the basis of excellent physical properties such as drawing processability, processing characteristics and price competitiveness. In particular, PET used for tire cords is advantageous in terms of economy and high strength, but has a disadvantage in that heat resistance is weak and low water resistance. Therefore, improvement of modulus retention at heat resistance and high temperature is required.

In general, PET is synthesized by condensation polymerization of terephthalic acid and ethylene glycol. First, it has excellent adhesion and coating properties to metal materials and textile products, and second, excellent weather resistance, thermal stability, insulation, and excellent appearance. Harmless point, fourth, it is excellent in dyeing, anti-pilling, etc., and has the same mechanical properties as conventional fibers. In spite of these various advantages, efforts are being made to achieve better performance, as mentioned above. Efforts to produce excellent PET / clay nanocomposites are one of them.

The preparation of polymer resin / clay nanocomposites is a method of improving the physical properties by adding a micron (10 ^-6 m) reinforcing agent, and dispersing the particle size of the inorganic filler / reinforcing agent to the nanometer scale. Its basic goal is to overcome the shortcomings of the system, and it is one of the key technologies that is expected to make a big difference in the next generation composite market in a very advantageous way in terms of cost performance.

In 1987, researchers in Japan and Japan have been reported by Toyota researchers in Japan and Japan since the separation of nylon monomers between silicate layers by an appropriate method and the interlayer polymerization increases the distance between layers by 10 nm. There was a problem that can be used only when possible and that existing industrial equipment cannot be used as it is.

In 1993, Yano et al. Prepared polyimide / clay nanocomposites by immersing montmorillonite (MMT) treated with an organic agent in a polymer solution to disperse the silicate layer by dispersing the silicate layer and maintaining this dispersion. However, a large amount of solvent is used in the manufacturing process and a separate solvent removal process is required, and there is a problem that the polymer is simply inserted into the organic layer of MMT, or the interlayer distance is narrowed again during the solvent drying process.

Nanoclay used in nanocomposites applied to existing PET and other polymers was treated with organic material having 8 or more alkyl groups for widening the gap between clay layers and compatibility with polymers. The organically treated nanoclays were limited because the intercalated polymers were involved in the reaction with the interlayer spacing of up to about 3 nm. If the clay layer spacing is exfoliated, it may affect the polymer properties to some extent. However, since they are at least 200 nm in length and width, they exist as foreign compounds in fiber structure. However, in the case of a molded article was used a lot because it serves to improve the gas barrier properties. The most inherent problem of organically treated nanoclays is that at high temperatures, most of the organically treated parts decompose and become unable to react with the polymer.

Compared to these nanoclays, POSS used in the present invention is an organic-inorganic hybrid nano-compound and maintains an organic portion at high temperature, and has a uniform distribution, thereby improving modulus retention at high temperature when applied to PET fibers, and having a modulus ratio of tanδ. The glass transition temperature due to the peak value can be significantly improved.

An object of the present invention is to solve the above problems in the polymerization step of 1.0 to 3.0% by weight of nano compound C ₅₉ H ₁₂₇ NO ₁₂ Si ₈ (Aminopropylisooctyl, hereinafter AMIO) having excellent thermal stability and compatibility with PET The high temperature produced by adding the ethylene terephthalate unit containing 85 mol% or more and a polyethylene terephthalate nanocomposite chip having an intrinsic viscosity in the range of 0.50 dl / g to 1.20 dl / g, followed by melt spinning and stretching the composite chip. To provide a method for producing a PET nanocomposite fiber with excellent modulus retention and glass transition temperature.

In order to solve the above problems, according to a preferred embodiment of the present invention, C ₅₉ H ₁₂₇ NO of the following structural formula (I) which is an amine polyhedral oligomeric silsesquixic acid after esterification of ethylene glycol and terephthalic acid and before condensation polymerization Prepared by melt spinning and stretching a polyethylene terephthalate nanocomposite chip containing at least 85 mol% of ethylene terephthalate units prepared by condensation polymerization by adding ₁₂ Si ₈ and having an intrinsic viscosity ranging from 0.50 dl / g to 1.20 dl / g. Provided is a method for producing polyethylene terephthalate nanocomposite fiber.

Structural Formula (I)

According to another suitable embodiment of the present invention, the molar ratio of ethylene glycol and terephthalic acid is 1.3: 1.0.

According to another suitable embodiment of the present invention, C ₅₉ H ₁₂₇ NO ₁₂ Si ₈ of Structural Formula (I) is characterized in that the addition of 1.0 to 3.0% by weight relative to the total polymer weight.

As described above, the POSS, C ₅₉ H ₁₂₇ NO ₁₂ Si ₈ (AMIO) used in the present invention can improve the modulus retention at high temperature when prepared from polyethylene terephthalate nanocomposite fiber, the glass transition temperature is It greatly increases the role. In addition, reproducibility was also confirmed by two measurements.

The present invention is to produce a polyethylene terephthalate nanocomposite fiber to which POSS, which is an organic-inorganic hybrid nanocompound having excellent heat resistance, is applied. In order to make the PET nanocomposite, PET polymerization was performed by adding 1.0 to 3.0 wt% of POSS having excellent thermal stability. If the added POSS content is 1.0% by weight or less, it is advantageous in dispersion, but it remains decomposed at high temperature and does not have an effect on PET heat resistance. When the POSS content is 3.0 wt% or more, the POSS particles form aggregates on their own, which is a problem in dispersion, and serves to lower physical properties, so that the weight of POSS is most preferably 1.0 wt% to 3.0 wt%.

PET is a DMT method produced by ester interchange of ethylene glycol (hereinafter referred to as 'EG') and dimethyl terephthalate (hereinafter referred to as 'DMT'), and EG and terephthalic acid. There is a TPA method produced by ester reaction with (terephthalic acid, hereinafter referred to as 'TPA').

Although the polymerization method of the present invention can be both TPA and DMT method, it is more preferable to prepare the polymer by the in situ method by the TPA method. Unlike the DMT method, which uses a metal (Mn) acetate as a catalyst for the esterification reaction, in the TPA method, a bishydroxyethylterephthalate (hereinafter referred to as 'BHET') oligomer obtained by the esterification reaction without a special catalyst is esterified. The reaction is carried out by autocatalyst in a certain amount in the reaction tank, because the oligomer or the proton (H ⁺ ) of the -COOH group of TPA catalyzes.

It is preferable that the molar ratio of EG and TPA is 1.3: 1.0 by TPA method. Since this is a semi-batch method in which a slurry (slurry, TPA and EG mixture) is added little by little in the esterification reaction, the viscosity of the added slurry should be more than a certain level so that it is easy to operate. Advantageously, however, excess EG reacts with two molecules to produce diethylene glycol (hereinafter referred to as 'DEG') as a byproduct. Since there is a problem of decreasing the crystallization rate due to the lowering of the melting point of PET and the uniformity due to the difference in the chain length, the molar ratio of EG and TPA in the process is preferably 1.0 to 1.5: 1.0, and the present process has a DEG of 1.0wt% or less. The molar ratio was chosen to be 1.3: 1.0 without affecting the physical properties. At the end of the esterification reaction, the POSS dispersed in the molten oligomer is added before the condensation reaction is started and transferred to the condensation reaction to complete the reaction.

In this case, the POSS is dissolved in a solvent (THF) and dispersed in EG beforehand. That is, in order to improve the dispersion, it was dispersed in EG using a solvent and an ultrasonic disperser, and the dispersed EG solution was confirmed to be slightly opaque due to the nano compound.

The advantage of POSS is that it has excellent thermal stability, particle size is nanoscale (100 nm or less), and has organic / inorganic functional groups, thereby having various reactivity. Thermal stability was confirmed by a thermogravimetic analyzer (TGA), and the amount (weight) of C ₅₉ H ₁₂₇ NO ₁₂ Si ₈ (AMIO) decomposed to 280 ° C, the PET polycondensation temperature, Since it becomes 2%, it is thermally stable in the polymerization process and reacts and disperses in PET to affect physical properties. Conventional organically treated nanoclays do not affect physical properties since most of the organicated parts are decomposed at high temperatures. However, in the case of a molded article, even if the organic part is decomposed, the clay remains intact, and it can be seen that the gas barrier property is improved. POSS is also a uniform particle with a particle size of less than 100 nm, and simultaneously contains organic / inorganic functional groups and a large amount of organic functional groups are present at high temperature, thereby reacting and dispersing the PET polymer to affect physical properties. It was found that the reactivity and dispersibility were significantly superior to nanoclays of 200 nm or more.

The molecular formula of POSS, the organic-inorganic hybrid nano-compound used in the present invention is (RSiO _1.5 ) _n , and has a variety of structures depending on the type and n of the alkyl group R is applicable to various polymers.

The R group of POSS used in the present invention is isooctyl as an alkyl group, and the functional group is selected from C ₅₉ H ₁₂₇ NO ₁₂ Si ₈ (AMIO) having an amine group having good compatibility with PET. It was purchased directly from the company used without purification, the three-dimensional structure is shown in the formula (1).

A PET nanocomposite containing 2.0 wt% of C ₅₉ H ₁₂₇ NO ₁₂ Si ₈ (AMIO) nano-compound was polymerized to prepare a cross-section and then vacuum dried at 70 ° C. below the crystallization temperature, and then the cross-section thereof was scanned by Electron Microscopy. The particle size and dispersibility were analyzed and evaluated by SEM and Atomic Force Microscopy. C ₅₉ H ₁₂₇ NO ₁₂ Si ₈ (AMIO) -POSS is a viscous liquid state that the nanomaterials themselves agglomerate with each other, so that some aggregates larger than 100 nm can be observed, but have a uniform distribution around 80 nm. It could be confirmed that (Fig. 1).

The polymer of the PET nanocomposite was vacuum dried at 70 ° C. for 24 hours and then fabricated at 265 ° C. using a rheometer. This fiber was sufficiently drawn in an oil bath, washed with carbon tetrachloride, and dried at room temperature. Storage modulus according to high temperature was measured through kinetic analysis and normalized to compare modulus retention, and PET nanocomposite fiber added AMIO-POSS 2.0 wt% at 120 ° C has a modulus retention of 45 to 47%. It was found that pure PET is improved by 10 to 15% or more compared with 30 to 35%. In addition, as a result of measuring twice, it was confirmed that the modulus retention rate was reproducible (FIG. 2). In addition, it can be seen that the glass transition temperature, which is the peak value of tanδ calculated by the modulus ratio compared to PET, moves to the right (high temperature direction), and PET is AMIO-POSS. PET nano composite fiber added 2.0 wt% can be seen that the 118 to 120 ℃ is increased by about 30 ℃ or more.

Thermal stability evaluation of POSS was carried out in the following manner.

(1) Thermal Stability of POSS

Thermogravimetric Analysis (TGA) analysis was performed to investigate the thermal stability of the POSS. Prior to TGA analysis, all samples were sufficiently dried in a vacuum oven (40 ° C.) and all TGA analyzes were performed at a temperature rising rate of 10 ° C./min over a temperature range of 30 to 800 ° C. while flowing nitrogen gas.

As a result of confirming the thermal stability of the POSS in the present invention, it was found that C ₅₉ H ₁₂₇ NO ₁₂ Si ₈ (AMIO) at 280 ° C. was maintained at 98% at the PET polymerization temperature when 2% decomposition occurred and was added during the polymerization.

The addition amount was selected to 2.0% by weight relative to the PET polymer, dissolved in a solvent (THF) and sufficiently dispersed by an ultrasonic disperser. Good dispersion can be seen to slightly blur the transparency of the entire EG solution.

≪ Example 1 >

The molar ratio of ethylene glycol and terephthalic acid is added to the polymerization reactor at 1.3: 1.0 to complete the esterification reaction. Water may be obtained through esterification at 230 ° C. for 4 hours. Subsequently, a little TMP catalyst was added as a thermal stabilizer for the condensation polymerization reaction, an antimony (Sb) catalyst was added thereto, and a viscous liquid C ₅₉ H ₁₂₇ NO ₁₂ Si ₈ (AMIO) -POSS 2.0 wt% was added thereto. While running under vacuum for 2 hours at 280 ℃ to obtain a PET nanocomposite chip having an intrinsic viscosity of 0.7dl / g. The prepared PET nanocomposite chip was subjected to solid state polymerization (hereinafter referred to as 'SSP') to increase the intrinsic viscosity to 1.0 dl / g. The SSP chip was vacuum dried at 70 ° C. for 24 hours, and then spun and stretched at 265 ° C. using a rheometer to prepare fibers for kinetics analysis.

Comparative Example 1

PET SSP chip (IV = 1.0) without any POSS was prepared, and vacuum dried at 70 ° C. for 24 hours, followed by spinning and stretching at 265 ° C. using a rheometer, and subjected to kinetic analysis.

In the case of Example 1, the dispersibility is uniformly distributed throughout the size of about 80nm, it can be confirmed that some aggregates of 100nm or more due to the aggregation between nanomaterials. Storage modulus retention at 120 ℃ was 45% more than PET increased 10-15% compared to PET in the AMIO-POSS 2.0% by weight added PET was confirmed that the modulus retention is significantly superior to PET. In addition, the results of two measurements to confirm the reproducibility was confirmed to show almost similar results. And, it can be seen that the glass transition temperature, which is the peak value of tanδ, calculated as the PET nanocomposite fiber modulus ratio to which the AMIO-POSS 2.0 wt% is added, moves to the right (high temperature direction), and it is about 30 ° C., which is about 30 It can be seen that the increase over ℃.

1 is a SEM (1a), 2-D AFM (2b) and 3-D AFM (1c) photographs of the cross-section of PET nanocomposite fiber added 2.0% by weight of the amine-based POSS.

2 shows normalized change curves of storage modulus according to temperature of PET nanocomposite fibers added with PET and amine-based POSS 2.0% by weight.

Figure 3 shows tanδ, the ratio of storage modulus and loss modulus according to the temperature of PET and amine-based POSS 2.0 wt% added PET nanocomposite fiber.

Claims (3)

Ethylene tere prepared by esterification of the molar ratio of ethylene glycol and terephthalic acid in which C ₅₉ H ₁₂₇ NO ₁₂ Si ₈ of the structural formula (I), which is an amine polyhedral oligomer silsesquixic acid, is dispersed at 1.3: 1.0 A method for producing polyethylene terephthalate nanocomposite fibers prepared by melt spinning and stretching a polyethylene terephthalate nanocomposite chip containing 85 mol% or more of phthalate units and having an intrinsic viscosity in the range of 0.50 dl / g to 1.20 dl / g. Structural Formula (I)

delete The method of claim 1, wherein C ₅₉ H ₁₂₇ NO ₁₂ Si ₈ of Structural Formula (I) is added at 1.0 to 3.0% by weight based on the total weight of polyethylene terephthalate.

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