JP2012188528A - Polyester chip with high polymerization degree and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyester chip with a high polymerization degree which has quality stability, has reduced thread breakage and fuzzes, and can achieve stable silk reeling, and to provide a method for producing the same.SOLUTION: The following means are used: a polyester chip with a high polymerization degree obtained by being subjected to solid phase polymerization and having an intrinsic viscosity (IV) of 1.25 to 1.45, and has melting properties to the OCP of the following (1) and (2): (1) the amount of unmelted polymer when being melted at 145°C for 10 min is 0.1 to 1 wt.%; and (2) the amount of an unmelted polymer when being melted at 160°C for 10 min is 0 wt.%; and a production method which is performed under the specified conditions respectively where (a) the moving speed of polyester chip, (b) the temperature, (c) the flow rate of an inert gas and (d) the introduction temperature in a solid phase polymerization tank 3, (e) the relation between the moving amount of the polyester chip and the flow rate of the inert gas in a preheating tank, and (f) the relation between the moving amount of the polyester chip and the inert gas in the solid phase polymerization tank.

Description

  The present invention relates to a polyester chip having a high degree of polymerization, and more specifically to a high degree of polymerization polyester chip suitable for high strength, high elastic modulus / low shrinkage polyester fibers and a method for producing the same. In particular, the high-polymerization degree polyester chip of the present invention is characterized by being a uniform high-polymerization degree polyester chip having a small IV difference between chips and a small IV difference between inner and outer layers in the chip.

  The present invention relates to a fiber for a high elastic modulus / low shrinkage polyester tire cord particularly useful as a carcass material for a passenger car radial tire, particularly a high strength, high elastic modulus / low shrinkage polyester tire cord. The present invention provides a polyester chip having a high degree of polymerization and a method for producing the same, in which the quality of the fiber for use in the production of the fiber for the printing is stable, and the yarn can be stably produced with little yarn breakage and fluff.

  Polyester tire cords are used as the carcass material for radial tires for passenger cars. Recently, polyester fibers for tire cords are mainly high modulus and low shrinkage polyester. Fiber (hereinafter referred to as HMLS-PET) is used. This is because it has excellent handling stability and durability during high-speed driving. Polyester fibers for general industrial materials have high strength but high heat shrinkage, they cannot exhibit high elasticity and low shrinkage as tire cords, and steering stability and durability at high speeds are not sufficient. It is.

  The HMLS-PET spinning process usually employs a high-speed spinning direct thermal drawing method, and is carried out at a spinning speed of 2000 m / min or more and a winding speed of about 5000 m / min or more. This high speed spinning is a necessary condition for obtaining a highly oriented undrawn yarn necessary for the production of HMLS-PET. In contrast, polyester fibers for general industrial materials require unoriented yarns with as low orientation as possible to obtain high strength yarns.

  The high-speed spinning direct thermal drawing method has various technical problems, and a stable production technique for HMLS-PET has been established so far to solve these difficulties. For example, the development of a low-pressure loss filter, uniform and efficient cooling technology, and hot rolls and yarns associated with high-speed hot drawing to increase the filtration pressure of the spinning pack due to an increase in the discharge rate accompanying high-speed yarn production There are developments of low-friction oils to reduce friction with strips, optimization of hot roll surface roughness and improvement of wear resistance, development of heat-resistant oils that can withstand high-temperature hot drawing, and the like.

  With the spread of HMLS-PET tire cords in passenger car radial tires, recently, HMLS-PET with higher strength has been required to reduce the weight of the tires, and further improvement in the spinning technology is necessary. It became.

  Production of higher strength HMLS-PET is possible mainly by taking advantage of the potential of polyester chips with a higher degree of polymerization. However, when manufacturing a polyester chip having a higher degree of polymerization, there are some difficulties in maintaining the same high quality as that of a conventional polymer for HMLS-PET.

  In order to obtain a polymer having a high degree of polymerization, it is necessary to increase IV, and solid phase polymerization is required for a long time. However, if conventional equipment is used, the residence (reaction) time naturally becomes longer and the production volume decreases. It will be. Therefore, in order to increase the solid-phase polymerization temperature and not to extend the residence (reaction) time as much as possible so as not to reduce the productivity so much, the resulting high polymerization degree polyester chip has a significant IV difference between the chips, In some cases, some high IV chips exceeding the management width are generated. When such a high IV chip is produced and mixed into a normal IV chip, the quality is not stable, and yarn breakage and fluff frequently occur during yarn making, which makes stable production impossible.

  Therefore, it is necessary to supply a polyester chip having a high degree of polymerization capable of stable yarn production with less fiber breakage and fluff, particularly for high-strength HMLS-PET tire cords. Specifically, it is necessary to produce a uniform highly polymerized polyester chip having a small IV difference between chip particles.

  Conventionally, as shown in Patent Document 1, solid-state polymerization of a polyester chip while forming a stabilized flow of a deposition layer moving by gravity and passing an inert gas countercurrently to the deposition layer And a method for producing a highly polymerized polyester chip, a highly polymerized polyester chip having a small difference in intrinsic viscosity and crystallinity between inner and outer layers of the chip as shown in Patent Document 2, or Patent Document 3 Polyester chips prepared by a method for preventing adhesion of polyester chips to each other and adhesion to a solid-phase polymerization apparatus have been used. However, in these methods, particularly for high-strength HMLS-PET tire cords, It was difficult to obtain a polyester chip having a high degree of polymerization and a high degree of polymerization capable of stable yarn production with little yarn breakage and fluff. Therefore, it has been desired to solve this problem.

Japanese Patent Publication No. 47-25719 Japanese Patent Application Laid-Open No. 5-70567 JP-A-9-59363

  An object of the present invention is to provide a polyester tire cord having a high elastic modulus and a low shrinkage rate which is particularly useful as a high modulus / low shrinkage polyester tire cord which is useful as a carcass material for a passenger car radial tire. The present invention is to provide a polyester chip having a high degree of polymerization and a method for producing the same, in which the quality of the fiber for use in the manufacturing process is stable, and the yarn can be stably produced with less yarn breakage and fluff.

The above-described problems of the present invention can be solved by applying the following means.
1. Polyethylene terephthalate chips are high-polymerization degree polyester chips having an intrinsic viscosity (IV) of 1.25 to 1.45 obtained by solid-phase polymerization, and the following (1) and (2) OCP solubility characteristics Polyester chip having a high degree of polymerization.
(1) The undissolved polymer is 0.1 to 1% by weight when 2000 mg of polyester chip is dissolved in 25 ml of OCP at 145 ° C. for 10 minutes.
(2) Undissolved polymer is 0% by weight when 2000 mg of polyester chip is dissolved in 25 ml of OCP at 160 ° C. for 10 minutes.
2. 2. The high degree of polymerization polyester chip according to claim 1, wherein IV of the surface layer portion of the high degree of polymerization polyester chip is 1.25 to 1.60.
3. 3. The high-polymerization polyester chip has a carboxyl end group (COOH) of 8 to 16 eq / t, and a diethylene glycol (DEG) content of 0.5 to 1.0% by weight. High polymerization degree polyester chip.
4). A method for producing a polyester chip having a high degree of polymerization having an intrinsic viscosity (IV) of 1.25 to 1.45 obtained by solid-phase polymerization of a polyethylene terephthalate chip, wherein the polyester chip deposition layer that is moved by gravity is stable. When the polyester chip is heated and solid-phase polymerized while the flow is formed and the inert gas is passed countercurrently to the deposited layer of the polyester chip, the following conditions in the preheating tank and the solid-phase polymerization tank are satisfied. A method for producing a polyester chip having a high degree of polymerization, characterized by satisfying (a) to (f).
(A) Movement amount of polyester chip 400 to 2,000 kg / hr
(B) Temperature of polyester chip Preheating tank: 180 to 218 ° C
Solid phase polymerization tank: 180-220 ° C
(C) Supply temperature of inert gas Preheating tank: 180-220 ° C
Solid phase polymerization tank: 10-60 ° C
(D) Flow rate of inert gas Preheating tank: 2,500 to 18,000 m ³ / hr
Solid state polymerization tank: 250-3,000 m ³ / hr
(E) Movement amount of polyester chip in preheating tank / flow rate of inert gas = 0.12 to 0.19 kg / m ³
(F) Movement amount of polyester chip in solid phase polymerization tank / flow rate of inert gas = 1.2 to 1.5 kg / m ³

  By using the high-polymerization degree polyester chip of the present invention, fibers for high-strength, high-modulus and low-shrinkage polyester tire cords can be produced with stable quality, quality and excellent yield.

  Further, when the high polymerization degree polyester chip of the present invention is used as a fiber for standard strength high elastic modulus and low shrinkage polyester tire cords, or as a polyester fiber for general materials, a product of further excellent quality and quality Can be produced with good yield.

The main part of the solid-phase polymerization apparatus for manufacturing the high polymerization degree polyester chip | tip of this invention is shown.

The present invention relates to a polyester chip having a high polymerization degree IV of 1.25 to 1.45 obtained by solid-phase polymerization of a polyethylene terephthalate chip, and the following O-chlorophenols (1) and (2): This is a high-polymerization degree polyester chip having a solubility characteristic with respect to ru (hereinafter referred to as OCP).
(1) The undissolved polymer is 0.1 to 1% by weight when 2000 mg of polyester chip is dissolved in 25 ml of OCP at 145 ° C. for 10 minutes.
(2) Undissolved polymer is 0% by weight when 2000 mg of polyester chip is dissolved in 25 ml of OCP at 160 ° C. for 10 minutes.

  The polyethylene terephthalate chip in the present invention is a chip made of a polyester polymer composed of a bifunctional carboxylic acid mainly composed of terephthalic acid and a glycol component mainly composed of ethylene glycol. Copolymers in which a portion of terephthalic acid is replaced with 2,6-naphthalenedicarboxylic acid, 4,4-dicarboxyphenoxyethane, isocyanate groups, and the like can also be used. However, a copolymer polymer in which a part of ethylene glycol is replaced with diethylene glycol, propylene glycol, butanediol or the like does not satisfy the high elastic modulus / low shrinkage polyester fiber characteristics intended by the present invention. Therefore, it is not preferable to use it except for a very small amount.

  The polyethylene terephthalate chip to be used for the solid phase polymerization of the present invention is one having an IV of 0.5 to 0.75, preferably 0.6 to 0.7 by liquid phase polymerization. As the liquid phase polymerization method, known methods can be used. For example, as an esterification catalyst and / or a polymerization catalyst, antimony trioxide, antimony acetate or the like is 150 to 300 ppm as antimony, and a heat resistant agent is inorganic and / or organic. A phosphorus compound can be used in an amount of 0 to 100 ppm as phosphorus. Furthermore, it is also possible to add 0 to 100 ppm of manganese compounds and cobalt compounds as respective metals as light-proofing agents and color tone improvers.

  The additive such as the catalyst affects the thermal dimensional stability as a fiber for tire cord through the influence on the orientation crystallization behavior when spinning the polyethylene terephthalate fiber, or the polymer insoluble foreign matter and Therefore, it is necessary to apply optimum conditions to cause thread breakage and fluff.

The intrinsic viscosity (IV) of the polyester chip of the present invention is required to be from 1.25 to 1.45. By setting the intrinsic viscosity (IV) within the above range, the polyester chip of the present invention has high strength and high strength. A polyester fiber having an elastic modulus and a low shrinkage can be obtained.
The intrinsic viscosity (IV) is preferably 1.3 to 1.4, more preferably 1.32 to 1.38. If the IV is less than 1.25, it is not possible to stably obtain a polyester fiber having a high strength, a high elastic modulus and a low shrinkage rate from the polyester chip of the present invention. Only moderate strength (less than 7.0 cN / dtex) can be produced stably. On the other hand, when the IV exceeds 1.45, polyester fibers of the present invention can be obtained with high strength, high elastic modulus and low shrinkage, but the yarn breaks frequently during yarn production and fluff frequently occurs. This is not preferable because the quality and yield of the product are reduced. Further, even if IV is increased beyond 1.45, it is difficult to obtain a polyester fiber having higher strength, higher elastic modulus and lower shrinkage. Furthermore, if the IV exceeds 1.45, an insoluble polymer is generated when the polyethylene terephthalate chip is melted at 160 ° C. for 10 minutes.

When 2000 mg of the highly polymerized polyester chip of the present invention is dissolved in 25 ml of OCP at 145 ° C. for 10 minutes, the undissolved polymer is 0.1 to 1% by weight, preferably 0.2 to 0.5% by weight. When the undissolved polymer is less than 0.1% by weight, the polyester chip IV is often less than 1.25, while when it exceeds 1% by weight, the IV may exceed 1.45. Many.
When 2000 mg of the highly polymerized polyester chip of the present invention is dissolved in 25 ml of OCP for 10 minutes at 160 ° C., the undissolved polymer is 0% by weight, that is, the entire amount of the highly polymerized polyester chip of the present invention is dissolved. When an undissolved product is produced under these dissolution conditions, yarn breakage and fluff frequently occur in the yarn production process of the high-strength, high elastic modulus, low-shrinkage polyester fiber of the present invention, and stable yarn production cannot be performed. The residual polymer that remains as an undissolved material when melted at 160 ° C. for 10 minutes is a thin-film film, which clearly indicates that a high IV polymer is formed on the surface layer of the chip. Although this undissolved polymer cannot measure the exact IV, for example, it is 1.6 because the data measured by dissolution for 10 minutes at 180 ° C. where partial hydrolysis occurs exceeds 1.6. It is estimated that it is considerably exceeded.

  Moreover, it is preferable that IV of the surface layer part of a chip | tip of this invention is 1.25-1.6, More preferably, it is 1.25-1.45. When the chip IV of the surface layer is less than 1.25, the polyester chip IV of the present invention is not satisfied. On the other hand, when it exceeds 1.6, an undissolved polymer is formed when dissolved in the OCP at 160 ° C. for 10 minutes, often resulting in a decrease in yarn-making property. Here, the surface layer portion of the chip means from the outer surface of the chip to the inside of 40 μm.

The polyester chip of the present invention preferably has a carboxyl end group (COOH) of 8 to 16 eq / t, and more preferably 8 to 14 eq / t. The smaller the carboxyl end groups, the better the heat resistance of the polyester fiber, but the lower temperature and longer polymerization conditions are applied. When the carboxyl end group is 8 to 16 eq / t, the high strength, high elastic modulus / low shrinkage polyester fiber of the present invention is used as a tire cord without significantly reducing the productivity. It has sufficient heat resistance and is preferable for high-performance radial tires for high-speed running.
The polyester chip of the present invention preferably has a diethylene glycol (DEG) content of 0.5 to 1.0% by weight, more preferably 0.5 to 0.8% by weight. Since ethylene glycol works as a copolymerization component of polyethylene terephthalate, if it is contained in a large amount exceeding 1% by weight, the melting point is lowered and the crystallinity is lowered. Since it is not necessary to add a large amount of catalyst by setting the content of diethylene glycol to 0.5 to 1.0% by weight, the polymer quality is not lowered, the melting point is lowered, and the crystallinity is not lowered. The thermal dimensional stability and heat resistance applied to the high-strength, high elastic modulus / low shrinkage polyester fiber according to the present invention are sufficient and preferable.
The highly polymerized polyester chip of the present invention having the above-described features is suitable for producing high-strength, high elastic modulus / low shrinkage polyester fibers having the following characteristics (1) to (2).
(1) IV = 0.95 to 1.05
(2) COOH = 10-20 eq / t
(3) Strength = 7-8 cN / dtex
(4) Elongation = 10-15%
(5) Intermediate elongation = 4.5 to 6.5%
(6) Dry heat shrinkage = 3-6%
The IV of the high strength, high elastic modulus and low shrinkage polyester fiber obtained from the polyester chip of the present invention is preferably 0.95 to 1.05, more preferably 0.98 to 1.05. If it is less than 0.95, it is difficult to obtain a stable strength. On the other hand, when IV exceeds 1.05, it becomes difficult to stably obtain polyester fibers satisfying the fiber characteristics (1) to (6).

  The COOH of the high strength, high elastic modulus and low shrinkage polyester fiber obtained from the polyester chip of the present invention is preferably 10 to 20 eq / t, more preferably 10 to 18 eq / t. When COOH is less than 10 eq / t, it is difficult to stably obtain polyester fibers satisfying the fiber characteristics (1) to (6). On the other hand, COOH exceeding 20 eq / t is not preferable because the heat resistance is not sufficient.

  The strength of the high strength, high elastic modulus and low shrinkage polyester fiber obtained from the polyester chip of the present invention is preferably 7 to 8 cN / dtex, more preferably 7.3 to 8 cN / dtex. If it is less than 7, it is hardly different from the conventional high elastic modulus and low shrinkage polyester fiber. On the other hand, if it exceeds 8, it is difficult to stably obtain a polyester fiber satisfying the above fiber characteristics (1) to (6). In addition, yarn breakage and fluff are generated, and it is difficult to produce stably.

  Further, the elongation of the high strength, high elastic modulus and low shrinkage polyester fiber obtained from the polyester chip of the present invention is preferably 10 to 15%, more preferably 11 to 14%. If the elongation is less than 11%, yarn breakage and fluff are generated, and stable yarn production is difficult. When the elongation exceeds 15%, sufficient strength is often not obtained.

  The intermediate elongation of the high strength, high elastic modulus and low shrinkage polyester fiber obtained from the polyester chip of the present invention is preferably 4 to 7%, more preferably 4.5 to 6.5%. When the intermediate elongation is less than 4, the dry heat shrinkage rate is not sufficient, while when it exceeds 7%, sufficient strength may not be obtained.

  The dry heat shrinkage rate of the polyester fiber having high strength, high elastic modulus and low shrinkage obtained from the polyester chip of the present invention is preferably 3 to 6%, more preferably 3 to 5%. When the dry heat shrinkage rate is less than 3%, sufficient strength cannot be obtained. On the other hand, when the dry heat shrinkage rate exceeds 6%, it is difficult to obtain a tire code with good dimensional stability.

  The high-strength, high-elasticity / high-shrinkage polyester fiber of the present invention has high strength and high toughness when used as a rubber reinforcing material for tire cords, rubber hoses, rubber belts, etc. Excellent and excellent durability such as fatigue resistance and heat resistance.

  Next, the main requirements in the method for producing a highly polymerized polyester chip of the present invention are as follows.

A method for producing a polyester chip having a high polymerization degree IV (intrinsic viscosity) of 1.25 to 1.45 obtained by solid-phase polymerization of the polyethylene terephthalate chip of the present invention, wherein the polyester chip is deposited by gravity. When the polyester chip is heated and solid-phase polymerized while forming a stable flow of the layer and the inert gas is passed counter-currently to the deposited layer of the polyester chip, (B) Polyester chip movement speed, (b) Polyester chip temperature, (c) Inert gas flow rate, (d) Inert gas introduction temperature, (e) Polyester chip movement in the preheating tank The relationship between the amount of the inert gas and the flow rate of the inert gas, and (f) the relationship between the amount of movement of the polyester chip in the solid-phase polymerization tank and the inert gas should be performed under the following conditions, respectively. And butterflies.
(A) Movement amount of polyester chip: 400 to 20,000 kg / hr
(B) Temperature of polyester chip
Preheating tank: 180-218 ° C
Solid phase polymerization tank: 180-220 ° C
(C) Supply temperature of inert gas
Preheating tank: 180-220 ° C
Solid phase polymerization tank: 10-60 ° C
(D) Flow rate of inert gas Preheating tank: 2,500 to 18,000 m ³ / hr
Solid state polymerization tank: 250-3,000 m ³ / hr
(E) Movement amount of polyester chip in preheating tank / flow rate of inert gas = 0.12 to 0.19 kg / m ³
(F) Movement amount of polyester chip in solid phase polymerization tank / flow rate of inert gas = 1.2 to 1.5 kg / m ³
In the method for producing a polyester chip of the present invention, the inert gas used for the solid-phase polymerization of the polyester having a high degree of polymerization may be a gas inert to the polyester polymer, for example, a gas such as nitrogen, argon or helium. Usually, nitrogen gas is used.

  In the method for producing a polyester chip according to the present invention, the solid-state polymerization method for a polyester chip having a high degree of polymerization forms a stable flow of the polyester chip deposition layer moving by gravity, and the counter current flows against the polyester chip deposition layer. In this method, a polyester chip is heated while passing an inert gas and solid phase polymerization is performed. That is, the flow of the polyester chip is determined by the amount of the solid-state polymerization chip extracted from the lower part of the solid-phase polymerization tower. After the polyester chip is charged into the solid-phase polymerization tower apparatus, the movement of the chip other than gravity The driving force is not required. That is, since stirring of a screw or the like is not performed, a chip powder is hardly generated, and a high-quality polyester chip with a high degree of polymerization can be manufactured. Since the chip powder has a remarkably small surface area compared to a normal polyester chip, solid-state polymerization is likely to proceed, and high IV tends to occur. And it often becomes IV exceeding 1.6, and it is easy to produce | generate an insoluble polymer on the melt | dissolution conditions in this invention. Therefore, prior to solid phase polymerization, the powder mixed and attached to the chips is removed, and the chips after solid phase polymerization are also removed immediately before being supplied to the yarn hopper. Usually, a cyclone type powder removing device is attached to the position before and after the solid phase polymerization step for removing the powder. The powder mixed and adhered to the chips supplied to the yarn hopper is 200 ppm or less, preferably 100 ppm or less, more preferably 50 ppm or less.

  In the solid-phase polymerization method of the high-polymerization degree polyester chip of the present invention, the amount of movement of the polyester chip passing through the preheating tank and the solid-phase polymerization tank is 400 to 2,000 kg / hr, and the annual production is about 3,200 to 16, It is optimal for carrying out solid-state polymerization of a small amount to a medium amount of about 000 t / year.

  In the solid-state polymerization method of the high-polymerization degree polyester chip of the present invention, the temperature of the polyester chip in the preheating tank and the solid-phase polymerization tank is 180 to 220 ° C, and preferably both are 205 to 215 ° C. If the temperature of the polyester chip in the preheating tank and the solid-phase polymerization tank is less than 180 ° C., the solid-state polymerization rate of the polyester chip becomes slow, and the target production rate may not be obtained. On the other hand, if it exceeds 220 ° C., solid phase polymerization tends to proceed rapidly and non-uniformly, and an insoluble polymer is often produced under the dissolution conditions in the present invention, which is not preferable.

  Next, in the solid phase polymerization method of the high polymerization degree polyester chip of the present invention, the temperature of the inert gas supplied to the preheating tank is 180 to 218 ° C, and preferably 205 to 215 ° C. When the supply temperature of the inert gas is less than 180 ° C., the temperature of the polyester chip in the solid phase polymerization tank does not rise to 180 to 220 ° C., and the solid phase polymerization rate decreases. On the other hand, if it exceeds 218 ° C., the temperature of the polyester chip in the solid phase polymerization tank also exceeds 220 ° C., and the IV becomes too high, so that insoluble polymers are often produced under the dissolution conditions of the present invention.

  Moreover, in the solid-phase polymerization method of the high polymerization degree polyester chip of this invention, the temperature of the inert gas supplied from the lower part of a solid-phase polymerization tank is 10-60 degreeC. Preferably it is 30-50 degreeC. The supply temperature of the inert gas may be less than 10 ° C. However, in the solid phase polymerization process of the present invention, after the inert gas is passed through the solid phase polymerization tank and the preheating tank, the temperature is once lowered to the inert gas. Water, ethylene glycol, and the like contained therein are adsorbed by an adsorption tower, but considering the adsorption efficiency and cooling energy, a temperature range of 10 to 60 ° C. is appropriate. On the other hand, it is preferable that the high-temperature polyester chip after solid-phase polymerization is exchanged with the inert gas supplied from the lower part of the solid-phase polymerization tank and cooled as soon as possible, but the inert gas exceeds 60 ° C. The temperature cannot be cooled sufficiently.

  The inert gas supplied from the lower part of the solid-phase polymerization tank is heat-exchanged with a high-temperature polyester chip subjected to solid-phase polymerization that moves by gravity, heated, and sent to the upper side of the solid-phase polymerization tank. At this time, the inert gas absorbs low molecular weight polyester materials such as water, ethylene glycol and oligomers emerging from the surface of the polyester chip.

  Energy can be saved by supplying all or part of the inert gas discharged from the solid phase polymerization tank to the preheating tank and heating the chips of the preheating tank.

  Furthermore, the solid-state polymerization method for high-polymerization polyester chips of the present invention is a very energy-saving process in which heat generated by crystallization of a polyester chip is used for solid-phase polymerization after being preheated in a preheating tank. is there. However, if the heat of crystallization of the polyester chip is not uniformly exchanged with an inert gas, the heat of crystallization partially accumulates and becomes high temperature, and the chip in that part exceeds the scope of the present invention due to excessive solid-phase polymerization. This leads to a high IV chip, which generates insoluble polymers and causes variations in chip IV.

In solid phase polymerization method of the high polymerization degree polyester chip of the present invention, the flow rate of the inert gas, 2,500~18,000m ³ / hr at preheater, in the solid-phase polymerization reactor with 250~3,000m ³ / hr is there. If the flow rate of the preheating tank is less than 2500 m ³ / hr, the temperature of the polyester chip supplied to the solid phase polymerization tank does not rise sufficiently, and the solid phase polymerization rate decreases. In addition, when the flow rate of the solid phase polymerization tank is less than 250 m ³ / hr, the water and ethylene glycol generated by the solid phase polymerization of the polyester polymer cannot be discharged uniformly and sufficiently, and the solid phase that flows downwardly flows. Heat exchange with the heating chip that has been polymerized is not sufficient, heat is accumulated locally, solid-phase polymerization of the chip at that portion proceeds, and an insoluble high IV chip tends to be generated. On the other hand, when the flow rate of the preheating tank exceeds 18,000 m ³ / hr, the temperature of the polyester chip supplied to the solid-phase polymerization tank rises too much, and the solid-phase polymerization proceeds too much to produce an insoluble high IV polymer, Solid phase polymerization proceeds non-uniformly and tends to cause IV variations.

  The flow rate of the inert gas supplied to the preliminary crystallization tank and the solid phase polymerization tank covers the movement amount of the polyester chip of the present invention, that is, the production amount. The relationship between the amount of movement of the polyester chip and the flow rate of the inert gas is as follows.

Movement amount of polyester chip in preheating tank / flow rate of inert gas = 0.12 to 0.19 kg / m ³
Movement amount of polyester chip in solid phase polymerization tank / flow rate of inert gas = 1.2 to 1.5 kg / m ³
When the ratio of the movement amount of the polyester chip in the preheating tank to the flow rate of the inert gas is less than 0.12 kg / m ³ , the polyester chip temperature does not rise sufficiently due to the residence time of the preheating tank, and the solid-phase polymerization rate decreases.
On the other hand, if it exceeds 0.19 kg / m ³ , the temperature of the polyester chip supplied to the solid phase polymerization tank will rise too much, so that the solid phase polymerization will proceed too much to produce an insoluble high IV chip, or the solid phase polymerization will not occur. It progresses uniformly and it becomes easy to produce variation of IV.

When the ratio of the movement amount of the polyester chip in the solid-phase polymerization tank to the flow rate of the inert gas is less than 1.2 kg / m ³ , heat exchange between the crystallization heat generated from the polyester chip and the inert gas in the solid tank polymerization tank Is not performed uniformly, heat of crystallization is partially accumulated and the temperature becomes high, and solid-state polymerization of the polyester chip in that portion proceeds too much to form a high IV chip exceeding the scope of the present invention, to produce an insoluble polymer, or chip IV This is not preferable because it causes a variation of. On the other hand, if the flow rate of the inert gas is low, the water and ethylene glycol produced by the solid phase polymerization are not sufficiently discharged out of the solid phase polymerization tank, and the solid phase polymerization rate may decrease. On the other hand, if the ratio of the movement amount of the polyester chip and the flow rate of the inert gas in the solid phase polymerization tank exceeds 1.5 kg / m ³ , the temperature of the polyester chip in the solid phase polymerization tank does not rise, and the solid phase polymerization rate is increased. Decrease, and productivity decreases. In addition, if the flow rate of the inert gas is large, the heat of crystallization partially accumulates and becomes high temperature, and solid-state polymerization of the polyester chip proceeds excessively at that portion, resulting in the formation of insoluble high IV chips, Proceeds non-uniformly and tends to cause IV variation.

  Next, a specific example of the method for producing a highly polymerized polyester chip of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows an example of a solid phase polymerization process used for producing the high polymerization degree polyester of the present invention. Mainly from crystallization tank (1), preheating tank (2), solid phase polymerization tank (3), blower (4), nitrogen heating device (5), nitrogen cooling device (6), adsorption tank (7), etc. It is configured.

The polyester chip to be solid-phase polymerized is continuously supplied to the crystallization tank. In the crystallization tank, the polyester chip is heated and crystallized by supplying nitrogen or air heated to 150 to 170 ° C., preferably 165 to 167 ° C. This is because when the polyester chip is exposed to high-temperature nitrogen or air in the subsequent preheating tank, the surface of the chip is melted and softened to prevent the chips from fusing together. The flow rate of heated nitrogen or heated air is 1,200 to 11,200 m ³ / hr, preferably 1,900 to 9300 m ³ / hr. The crystallization tank is determined in consideration of the temperature and residence time of the polyester chip so that the crystallinity of the polyester chip is 25 to 30%.

  The polyester chips supplied to the crystallization tank are charged with high-temperature heated nitrogen or air, and previously charged and deposited. At the same time, the surface softens and causes light fusion between the chips. . Usually several or more chips form a “stick” that is lightly attached. In the present invention, the “koshi” is unraveled by a propeller that rotates on the chip surface of the crystallization tank at a very low speed. The rotation speed of the propeller is 0.5-2 rpm, usually about 1 rpm is sufficient. If the rotational speed is increased or the propeller enters the inside of the chip surface layer, the chips of the crystallization layer are mixed up and down, and a uniform residence time cannot be maintained. To the last, it is preferable not to apply a force other than gravity to the polyester chip.

  The polyester chip out of the crystallization tank is sent to the preheating tank by gravity.

In the preheating tank of the present invention, the polyester chip is heated relatively rapidly to the same temperature as the heated nitrogen gas by the nitrogen gas heated to 180 to 218 ° C. by the nitrogen heating device (5). The flow rate of heated nitrogen is 2,500 to 18,000 m ³ / hr and is changed according to the movement amount (production amount) of the polyester chip, but the ratio of the movement amount of the polyester chip and the flow rate of the nitrogen gas is 0.12. ˜0.19 kg / m ³ .

  The nitrogen gas after heat exchange with the polyester chip in the preheating tank is reheated by the nitrogen heating device (5) or cooled by the nitrogen cooling device (6) and then sent to the adsorption tank (7).

  In the solid phase polymerization tank (3) of the present invention, the polyester chip is subjected to solid phase polymerization at 180 to 220 ° C., and a high polymerization degree polyester chip having an IV of 1.25 to 1.45 targeted by the present invention is obtained.

From the lower part of the solid phase polymerization tank (3), nitrogen at 10 to 60 ° C. is blown at a flow rate of 250 to 3,000 m ³ / hr. The flow rate of nitrogen is changed depending on the movement amount (production amount) of the polyester chip, but the ratio of the movement amount of the polyester chip and the flow rate of the nitrogen gas is 1.2 to 1.5 kg / m ³ .

  Nitrogen gas introduced from the lower part of the solid-phase polymerization tank (3) is sent upward from the upper part of the solid-phase polymerization tank, facing the polyester chip moving downward by gravity, and contacted with the high-temperature polyester chip for heat exchange Then, the temperature is raised to the temperature of the polyester chips that are sequentially heated and solid-phase polymerized. On the other hand, the solid-state polymerized polyester chip is sequentially cooled by exchanging heat with nitrogen gas and moved downward. The temperature of the polyester chip when drawn out from the solid phase polymerization tank is about 80 ° C to 140 ° C.

  Thus, the high polymerization degree polyester chip of the present invention can be obtained stably. The highly polymerized polyester chip of the present invention has a high IV with an IV of 1.25 to 1.40, has a solubility in OCP, and is a uniform polymer with little variation in IV between the inner and outer layers of the chip and between the chips. It is. The highly polymerized polyester chip of the present invention is suitable for producing polyester fibers having high strength, high elastic modulus and low shrinkage.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example, this invention is not limited at all by these Examples. In addition, the measuring method of each data in an Example is as follows.

Chip characteristics (1) IV: 12 g of a polyester chip was pulverized by a sample mill while being cooled with liquid nitrogen to form fine particles of 10 to 30 mesh. 2000 mg of polyester chip fine particles were weighed and collected in an Erlenmeyer flask, 25 ml of orthochlorophenol was added, and dissolved at 160 ° C. for 10 minutes while stirring with a magnetic stirrer. After cooling the solution to room temperature, the drop time was measured with an Ostwald viscometer, and the solution viscosity was determined using the following formula.

IV = {0.0242 × (T × K × d) /h+0.2634} × f
Where T: sample solution drop time (seconds)
K: Viscometer coefficient
d: Specific gravity of the sample solution
h: Viscosity of orthochlorophenol (centipoise)
f: Correlation coefficient (standard sample IV / standard sample IV measurement).

  (2) Chip surface layer IV: Using a microtome RM type manufactured by Microtome with a diamond blade attached, a 20 μm-thick section is cut from the surface of a polyester chip having a diameter of 3 mm toward the center of the chip. It cut out in order and the section | slice of the part of 20-40 micrometers from the chip | tip surface was used as the sample of a chip | tip surface layer part. The sample amount was 400 mg, the orthochlorophenol was 5 ml, and the measurement was carried out in the same manner as in Item 1 IV using a micro Ostwald viscometer.

  (3) Solubility: Polyester chip fine particles prepared in the same manner as the IV measurement in the above item 1 were stirred and dissolved at 145 ° C. for 10 minutes, cooled to room temperature, and filtered using 0.2 μ filter paper. The remaining residue was weighed to determine the amount of undissolved polymer. The solution adhering to the Erlenmeyer flask used for dissolution and the undissolved polymer were washed and filtered with orthochlorophenol at room temperature, and the residue in the washing solution was also added. The weight percentage of the amount of undissolved polymer with respect to the weight of 2000 mg of the polyester chip fine particles was calculated to determine the solubility in OCP.

  In addition, the same polyester fine particle sample was stirred and dissolved at 160 ° C. for 10 minutes, then cooled to room temperature, filtered in the same manner as described above, and the residue was weighed to determine the amount of undissolved polymer. The solubility for was determined.

  (4) COOH: The polyester chip was pulverized with a sample mill while being cooled with liquid nitrogen to form fine particles of 10 to 30 mesh. A test tube was charged with 800 mg of polyester chip fine particles and 15 ml of orthocresol, and dissolved at 160 ° C. for 10 minutes while stirring with a magnetic stirrer. This polymer solution was transferred to a 50 ml beaker. The solution adhering to the Erlenmeyer flask was washed with chloroform and added to the beaker sample solution. This beaker was set in an automatic titrator, titrated with a 1 / 50N caustic soda methanol solution, and the amount of COOH end groups was determined from the following formula.

COOH (eq / t) = {(A−B) × f × 0.02 × 10 ⁻³ } / S × 10 ⁶
Where A: titration of sample solution (ml)
B: Titration volume of blank test with chemicals only (ml)
f: titer of 1 / 50N caustic soda methanol solution
S: Sample amount (g).

  (5) DEG: 1.0 g of polyester chip is placed in a 100 ml Erlenmeyer flask and 3 ml of monoethanolamine is added. A condenser was attached to the flask, and the polyester was amine-decomposed at 200 to 250 ° C. over 30 to 60 minutes. Next, 20 ml of 1,6 hexanediol 5 mg / 20 ml methanol solution was added from the top of the condenser. Next, 5.0-7.0 g of terephthalic acid was added and shaken well. The Erlenmeyer flask was placed in water and cooled to room temperature. Subsequently, it filtered using the N0.5C filter paper, and put the filtrate into the 50 ml Erlenmeyer flask. 2 μl of the filtrate was taken and measured by gas chromatography to determine the amount of DEG.

The measurement conditions for gas chromatography are as follows.
Column: TENAX GC
glass column: 3.2 mm × 1.6 m
Temperature: Column 170 ° C, supplyport,
detector 200 ° C
Hydrogen: 30 ml / min.
Air: 800 ml / min.
Sensitivity: 10x16
Chart speed: 10 mm / min. .

Fiber characteristics (1) IV: The same as the IV measurement of the chip, except that 2000 mg of a polyester fiber sample was dissolved in 25 ml of orthochlorophenol at 100 ° C. for 30 minutes.

  (2) COOH: It was performed in the same manner as the chip COOH measurement except that 800 mg of a polyester fiber sample was dissolved in 15 ml of orthocresol at 100 ° C. for 30 minutes.

(3) Fineness: JIS L-1013 (1999) 8.3.1 Positive fineness a) Measured according to the A method at a predetermined load of 5 mN / tex × display tex number and a predetermined yarn length of 90 m.

  (4) Strength / Elongation / Intermediate Elongation: JIS L-1013 (1999) using “TENSILON” UCT-100 manufactured by Orientec Co., Ltd. in a temperature control room with an air temperature of 20 ° C. and a humidity of 65% RH. 8.5.1 Measured under constant speed extension condition shown in standard time test. At this time, the holding interval was 25 cm, the tensile speed was 30 cm / min, and the number of tests was 10. The elongation at break was determined from the elongation at the point showing the maximum strength in the SS curve. The intermediate elongation was the elongation at 4 cN / dtex stress.

  (5) Dry heat shrinkage rate: JIS L-1013 (1999) 8.18.2 Dry heat shrinkage rate a) Predetermined load at the time of sampling 5 mN / tex × number of displayed tex according to skein shrinkage rate (Method A), treatment The measurement was performed at a temperature of 150 ° C. and a predetermined load of 200 mN / tex × display tex number at the time of measuring the skein length.

  (6) Yarn breakage: The number of yarn breakage per 1 ton of production (times / t).

  (7) Fluff occurrence frequency: The obtained fiber package was rewound at a speed of 500 m / min, and a light-sensitive fluff detection device manufactured by Ohiro Co., Ltd. was installed at a location 2 mm away from the yarn being rewound. The contained fluff (single yarn breakage) was detected and evaluated based on the following criteria from the number of fluff per 100,000 m of yarn length.

0-40: ◎ (excellent)
41-80: ○ (Good)
81-120: △ (Slightly good)
121 or higher: × (defect)
[Example 1]
A polyester chip made of polyethylene terephthalate containing 260 ppm of antimony and 10 ppm of phosphorus as a catalyst, IV of 0.65, COOH of 25 eq / t and DEG of 0.7% by weight was obtained as shown in FIG. Solid phase polymerization was performed using a polymerization apparatus. The production capacity of the solid state polymerization apparatus is 15 t / day.

  The polyester chip was supplied to the crystallization tank (1) at a constant rate. The supply rate is 625 kg / hr.

Air heated to 165 ° C. was blown from the crystallization tank (1) at a flow rate of 2800 m ³ / hr to crystallize the surface layer of the polyester chip. The residence time of the polyester chip in the crystallization tank was 3.4 hours, and the crystallinity was 30%. The crystallized polyester chip was lowered by gravity and supplied to the preheating tank (2).

Next, nitrogen heated to 210 ° C. was blown from the preheating tank (2) at a flow rate of 4000 m ³ / hr to heat the polyester chip. The polyester chip stayed in the preheating tank for 4.2 hours and was heated to 211 ° C.

The preheated polyester chip was lowered and supplied to the solid phase polymerization tank (3) by gravity. Nitrogen at 45 ° C. was supplied at a flow rate of 420 m ³ / hr from the nitrogen supply part at the bottom of the solid phase polymerization tank (3) and was sent to the upper part of the solid phase polymerization tank. The polyester chip formed a deposited layer after the crystallization tank and descended by gravity to the preheating tank and the solid phase polymerization tank, and the solid phase polymerization reaction proceeded while generating heat of crystallization in the solid phase polymerization tank. Nitrogen introduced from the lower part of the solid phase polymerization tank is sent upward while exchanging heat with the high-temperature polyester chip subjected to solid-phase polymerization to become high-temperature nitrogen, and the water and ethylene glycol produced by the solid-phase polymerization are exchanged. It was absorbed and discharged from the upper part of the solid phase polymerization tank (3). The discharged nitrogen was mixed with newly introduced nitrogen, heated to 210 ° C. by a nitrogen heating device (5), and then introduced into the preheating tank. The maximum temperature of the polyester chip in the solid phase polymerization tank was 210 ° C., and the residence time in the solid phase polymerization tank (3) was 42.4 hours.

  The amount of the solid phase polymerization chip extracted from the solid phase polymerization tank was 625 kg / hr, and the temperature of the chip was 120 ° C. The solid-phase polymerization chip was once stored in a silo, and then air-fed using nitrogen for the spinning process.

  The characteristics of the obtained solid phase polymerization chip are shown in Table 1. Both of the characteristics and the present invention have characteristics of a high degree of polymerization polyester chip, and have characteristics in a particularly preferable range.

  As the spinning machine, an extruder type spinning machine of 90 mmφ was used, and melt spinning was performed at a temperature of 295 ° C. A 20 μm metal nonwoven fabric filter was attached to the spin pack and the molten polymer was filtered, and then spun through the die pores. The die hole used was a 0.6φ, 180 hole annular array type die. A heating cylinder having a length of 10 cm was attached directly under the base, and a high temperature atmosphere of 300 ° C. was formed between 15 cm from directly under the base. Further, a 10 cm heat insulating cylinder was attached immediately below the heating cylinder. The spun yarn was allowed to pass through the slow cooling zone, and then cooled by blowing hot air at 70 ° C. from the outside of the test piece using an annular cooling device. An emulsion oil was applied to the cooled and solidified yarn. The yarn was wound on a take-up roll at a temperature of 80 ° C. rotating at a speed of 2500 m / min, and then continuously stretched 1.7 times with a first drawing roll at 105 ° C. The HMLS-PET fiber of 1670 dtex-360 filament was obtained by extending | stretching 1.4 time with an extending | stretching roll, and finally giving a 3.8% relaxation process with the unheated relaxation roll.

  Table 2 shows the spinning conditions, the physical properties of the obtained fibers, and the spinning properties.

The high-polymerization degree polyester chip | tip of this invention was obtained by the above, and it turned out that a high intensity | strength high elastic modulus and low shrinkage | contraction rate polyester fiber can be manufactured stably by using this polyester chip | tip and yarn-producing HMLS fiber.
[Examples 2-3]
In the same manner as in Example 1, polyester chips having a high degree of polymerization were produced by changing various conditions within the range of solid-phase polymerization according to the present invention. The characteristics of the obtained solid phase polymerization chip are shown in Table 1. Further, HMLS fibers were produced using the chips to produce polyester fibers having high strength and high elastic modulus according to the present invention. Table 2 shows the spinning conditions, fiber properties and yarn properties, and tire cord properties.
[Comparative Example 1]
In the method described in Example 1, the inert gas supply temperature was out of the preferred range to produce a highly polymerized polyester chip. The characteristics of the obtained solid phase polymerization chip are shown in Table 1. Further, HMLS fibers were produced using the chips to produce polyester fibers having high strength and high elastic modulus according to the present invention. Table 2 shows the spinning conditions, fiber properties and yarn properties, and tire cord properties.
[Comparative Examples 2-3]
In the method described in Example 1, a highly polymerized polyester chip was produced with the inert gas supply amount outside the preferred range. The characteristics of the obtained solid phase polymerization chip are shown in Table 1. Further, HMLS fibers were produced using the chips to produce polyester fibers having high strength and high elastic modulus according to the present invention. Table 2 shows the spinning conditions, fiber properties and yarn properties, and tire cord properties.

DESCRIPTION OF SYMBOLS 1 Crystallization tank 2 Preheating tank 3 Solid phase polymerization tank 4 Blower 5 Nitrogen heating apparatus 6 Nitrogen cooling apparatus 7 Adsorption tank

Claims (4)

A high-polymerization degree polyester chip having an intrinsic viscosity (IV) of 1.25 to 1.45 obtained by solid-phase polymerization of a polyethylene terephthalate chip, wherein the following O-chlorophenols (1) and (2): A polyester chip having a high degree of polymerization having a solubility characteristic for ru (hereinafter referred to as OCP).
(1) An undissolved polymer is 0.1 to 1% by weight when 2000 mg of a highly polymerized polyester chip is dissolved in 25 ml of OCP at 145 ° C. for 10 minutes.
(2) The undissolved polymer is 0% by weight when 2000 mg of a highly polymerized polyester chip is dissolved in 25 ml of OCP at 160 ° C. for 10 minutes. The high polymerization degree polyester chip according to claim 1, wherein IV of the surface layer part of the high polymerization degree polyester chip is 1.25 to 1.60. The carboxyl terminal group (COOH) of the highly polymerized polyester chip is 8 to 16 eq / t, and the diethylene glycol (DEG) content is 0.5 to 1% by weight. High polymerization degree polyester chip. A method for producing a polyester chip having a high degree of polymerization having an intrinsic viscosity (IV) of 1.25 to 1.45 obtained by solid-phase polymerization of a polyethylene terephthalate chip, wherein the polyester chip deposition layer that is moved by gravity is stable. When the polyester chip is heated and solid-phase polymerized while the flow is formed and the inert gas is passed countercurrently to the deposited layer of the polyester chip, the following conditions in the preheating tank and the solid-phase polymerization tank are satisfied. A method for producing a polyester chip having a high degree of polymerization, characterized by satisfying (a) to (f).
(I) Movement amount of polyester chip: 400 to 2,000 kg / hr
(B) Temperature of polyester chip Preheating tank: 180 to 218 ° C
Solid phase polymerization tank: 180-220 ° C
(C) Supply temperature of inert gas Preheating tank: 180-220 ° C,
Solid phase polymerization tank: 10-60 ° C
(D) Flow rate of inert gas Preheating tank: 2500-18,000 m ³ / hr,
Solid phase polymerization tank: 250 to 3,000 m ³ / hr
(E) Movement amount of polyester chip in preheating tank / flow rate of inert gas = 0.12 to 0.19 kg / m ³
(F) Movement amount of polyester chip in solid phase polymerization tank / flow rate of inert gas = 1.2 to 1.5 kg / m ³

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