JP2015178552A - Polyethylene terephthalate resin composition and production method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyethylene terephthalate(PE) resin composition which is reduced in the content of cyclic trimers and the reproduction amount of cyclic trimers in melting, has a good color tone and excellent transparency (haze) and an intrinsic viscosity suitable for film formation and its production method.SOLUTION: A PET resin composition has a content of cyclic trimers of 0.50 wt.% or lower, an intrinsic viscosity of 0.60-0.70, a content of antimony element of 40-80 ppm and a molar ratio (M/P) of alkali metal elements plus alkaline earth metal elements to phosphorus elements of 2.0-5.4. A method of producing a PET resin composition comprises solid phase polymerization of a PET resin composition of an intrinsic viscosity of 0.40-0.52 at 200-230°C for 15-40 h.

Description

  The present invention relates to a polyethylene terephthalate resin composition and a method for producing the same. More specifically, a polyethylene terephthalate resin having a low content of the cyclic trimer and a regenerated amount of the cyclic trimer at the time of melting, good color tone, excellent transparency (haze), and an intrinsic viscosity suitable for film molding. The present invention relates to a composition and a method for producing the composition.

  Since the polyethylene terephthalate resin composition is excellent in both mechanical properties and chemical properties, it has high industrial value and is widely used for fibers, films, sheets, hollow molded articles and the like.

  In particular, since a film using a polyethylene terephthalate resin composition has excellent properties such as transparency and dimensional stability, it is a display device for liquid crystal displays used in televisions and mobile phones, protection of optical members, and magnetic recording. Widely used in IT-related applications such as media members.

  However, the polyethylene terephthalate resin composition contains a low molecular weight substance mainly composed of a cyclic trimer. The cyclic trimer is produced by an equilibrium reaction during the polycondensation reaction of the polyethylene terephthalate resin composition, and is deposited on the surface of the product by heating in the molding process or processing process of the polyethylene terephthalate resin composition, resulting in optical turbidity. , Bright spots, coarse protrusions, etc., are known to cause deterioration in product quality.

  For example, Patent Documents 1 and 2 propose a method for solid-phase polymerization of a polyethylene terephthalate resin composition at a temperature below the melting point in an inert gas atmosphere or under reduced pressure. However, although this method can reduce the cyclic trimer, at the same time, the polycondensation reaction of the polyester resin composition proceeds and the increase in intrinsic viscosity also increases, so that the viscosity of the polymer at the time of molding increases during molding. As a result, there is a problem that the load at the time of extrusion becomes large, or the polymer temperature rises due to shearing heat generation, and the cyclic trimer is regenerated.

  In order to solve the problem that the intrinsic viscosity of the polyethylene terephthalate resin composition increases, Patent Document 3 proposes a method of heat-treating the polyethylene terephthalate resin composition at a temperature below the melting point in an inert gas atmosphere. . However, although this method can reduce the cyclic trimer without increasing the intrinsic viscosity of the polyethylene terephthalate resin composition, there is a problem that the color tone is deteriorated.

Japanese Patent Laid-Open No. 3-47830 JP-A-2-296860 JP 2006-104444 A

  The object of the present invention is to solve these conventional problems, to reduce the content of the cyclic trimer and the amount of the cyclic trimer regenerated upon melting, to have good color tone, excellent transparency (haze), and film formation. The present invention provides a polyethylene terephthalate resin composition having an intrinsic viscosity suitable for the above and a method for producing the same.

  The above-mentioned problems include an alkali metal element having a cyclic trimer content of 0.50 wt% or less, an intrinsic viscosity of 0.60 to 0.70, an antimony element content of 40 to 80 ppm, and a polyethylene terephthalate resin. This is achieved by a polyethylene terephthalate resin composition having a molar ratio (M / P) of alkaline earth metal element to phosphorus element of 2.0 to 5.4.

  The polyethylene terephthalate resin composition of the present invention has a low content of cyclic trimer and a small amount of cyclic trimer when melted, has good color tone, excellent transparency (haze), and is suitable for film molding It is possible to provide a polyethylene terephthalate resin composition having a viscosity.

  Examples of the component of the polyethylene terephthalate resin composition of the present invention include terephthalic acid or an acid component mainly composed thereof as a dicarboxylic acid component, and ethylene glycol or a glycol component mainly composed thereof as a diol component.

  Moreover, if the polyethylene terephthalate resin composition in this invention is 20 mol% or less of a carboxylic acid component, 1 type, or 2 or more types of terephthalic acid and dicarboxylic acids other than the acid component which has this as a main component are used as a copolymerization component. Similarly, as long as it is 20 mol% or less of the glycol component, one or two or more glycol components other than ethylene glycol or a glycol component mainly composed of this can be included as a copolymer component. Furthermore, a trifunctional or higher polyfunctional compound may be included as a copolymerization component as long as the thermoplasticity is not impaired.

  The polyethylene terephthalate resin composition of the present invention has a cyclic trimer content of 0.50 wt% or less, and more preferably 0.45 wt% or less. When the content of the cyclic trimer is 0.50 wt% or less, the cyclic trimer is hardly deposited on the surface of the film at the time of film forming or in the film processing step. The lower limit of the content of the cyclic trimer is not particularly limited, but is 0.10 wt% or more in the present invention. When the amount is less than 0.10 wt%, the time required for solid-phase polymerization for reducing the cyclic trimer becomes long, so that the increase in intrinsic viscosity increases and the load during melt extrusion increases.

  The polyethylene terephthalate resin composition of the present invention has an intrinsic viscosity in the range of 0.60 to 0.70, and more preferably in the range of 0.63 to 0.67. When it is 0.60 or more, the mechanical properties at the time of film formation become good. If it is 0.70 or less, it is possible to reduce the rise in temperature due to shear heat generation during melt extrusion, which is preferable for suppressing regeneration of the cyclic trimer during melting, and during film formation due to thermal degradation of the polymer. It is preferable for preventing deterioration of mechanical properties.

  The polyethylene terephthalate resin composition of the present invention has an antimony element content in the range of 40 to 80 ppm, and more preferably in the range of 50 to 70 ppm. When the content of the antimony element is 40 ppm or more, the reduction of the cyclic trimer can be promoted smoothly. When the content of the antimony element is 80 ppm or less, the reproduction of the cyclic trimer at the time of melting is suppressed, and the color tone and transparency ( Haze) is also good and preferable.

  Examples of antimony compounds include antimony trioxide, antimony pentoxide, antimony acetate, and antimony salts of aliphatic carboxylic acids. Among these, polycondensation reactivity, the color of the resulting polymer, and the point that it can be obtained at low cost Antimony trioxide is preferably used.

  Antimony compound addition methods include powder, ethylene glycol slurry, ethylene glycol solution, etc., but it is possible to prevent coarsening due to antimony aggregation, resulting in better transparency (haze). The method of adding as a solution is preferable.

The polyethylene terephthalate resin composition of the present invention needs to contain an alkali metal compound, an alkaline earth metal compound, and a phosphorus compound in a range of M / P of 2.0 to 5.4. (However, in the formula, M represents an alkali metal element or alkaline earth metal element, and P represents the total number of moles per 10 ⁶ g of phosphorus element polyester.)
M / P is preferably in the range of 2.5 to 4.5. When the M / P is 2.0 or more, the volume specific resistance at the time of melting of the polyethylene terephthalate resin composition becomes low, and the electrostatic application casting method can be suitably used at the time of film forming, and is 5.4 or less. And preferable for suppressing the regeneration of the cyclic trimer during melting.

  Among the above metal compounds, for example, the valence of the alkali metal compound is monovalent, and the alkaline earth metal compound is a divalent metal compound. In the present invention, M defines a molar ratio represented by M / P based on a divalent metal compound. Therefore, when using metal compounds having different valences, M is calculated in consideration of the valence. The Therefore, for example, when an alkali metal compound is used, M / P is calculated with M being a value obtained by multiplying the number of moles of the alkali metal compound by 0.5. Moreover, about a phosphorus compound, it calculates by bivalence.

  Examples of alkali metal compounds include lithium, sodium and potassium carboxylates, iodides, hydroxides, etc., but the lithium compounds and potassium compounds are preferred because the resulting polymer has improved heat resistance and good color tone. Preferably used.

Alkaline earth metal compounds include magnesium, calcium, strontium, barium carboxylates, iodides, oxides, chlorides, etc. Among these, it is difficult to produce precipitated particles during melt polymerization, and the resulting polymer A magnesium compound is preferably used since the transparency (haze) is improved.
Examples of the phosphorus element compound include phosphoric acid, phosphorous acid, phosphonic acid, and ester compounds thereof. In particular, phosphoric acid and phosphoric acid ethyl ester are preferably used.

  The polyethylene terephthalate resin composition of the present invention preferably has a cyclic trimer regeneration rate of 0.010 wt% / min or less when melted at 300 ° C. When it is 0.010 wt% or less, precipitation of the cyclic trimer during film forming or in the film processing step can be suppressed, which is preferable. The lower limit of the cyclic trimer is not particularly limited, but is 0.002 wt% or more in the present invention. When it is less than 0.002 wt%, it is necessary to extremely reduce the content of the antimony element, and the melt polymerization or solid phase polymerization of the polyethylene terephthalate resin composition does not proceed smoothly, leading to a decrease in productivity.

  In the polyethylene terephthalate resin composition of the present invention, the b value of the color tone measured with a color difference meter is preferably 4.0 or less, and more preferably 3.5 or less. When it is 4.0 or less, since the polyethylene terephthalate resin composition has a small thermal history, it is preferable because regeneration of the cyclic trimer due to the thermally deteriorated product can be suppressed during melting.

A method for obtaining the above-described polyethylene terephthalate resin composition will be described below.
The method for producing the polyethylene terephthalate resin composition of the present invention can be obtained by solid-phase polymerization of a polyethylene terephthalate resin composition having an intrinsic viscosity of 0.40 to 0.52 at a temperature of 200 to 230 ° C. for 15 to 40 hours. it can.

  The intrinsic viscosity of the polyethylene terephthalate resin composition subjected to solid phase polymerization is preferably in the range of 0.40 to 0.52. If it is 0.40 or more, the amount of cyclic trimer decreases at a predetermined temperature or time, so that the productivity is good and this is preferable. When it is 0.52 or less, the cyclic trimer is decreased before the intrinsic viscosity of the polyethylene terephthalate resin composition is increased, which is preferable.

  The temperature at which solid phase polymerization is performed is preferably in the range of 200 to 230 ° C, and more preferably in the range of 210 to 220 ° C. When the temperature is 200 ° C. or higher, the reduction of the cyclic trimer proceeds smoothly. When it is 230 ° C. or lower, it is preferable to suppress coloring due to thermal deterioration of the polyethylene terephthalate resin composition.

  The time for performing solid phase polymerization is preferably in the range of 15 to 40 hours, and more preferably in the range of 20 to 30 hours. The time varies depending on the amount of the polymerization catalyst remaining in the polyethylene terephthalate resin composition and the treatment temperature, but a range of 15 to 40 hours is preferable for smoothly reducing the cyclic trimer.

The method of solid phase polymerization in the present invention is not particularly limited, but it is preferably performed, for example, under reduced pressure or in an inert gas atmosphere. As a reduced pressure, it is preferable to apply under reduced pressure of 6.5 to 0.013 kPa for smoothly proceeding with solid-phase polymerization and reduction of cyclic trimer. Examples of the inert gas atmosphere include rare gases such as helium, neon, and argon, nitrogen gas, and carbon dioxide gas. Among these, nitrogen is preferable because it is easily available. Moreover, it is preferable that the density | concentration of oxygen and a water | moisture content contained in these inert gas is 500 ppm or less from the point which suppresses the coloring by deterioration of a polyethylene-terephthalate resin composition.
The type of the solid phase polymerization apparatus used in the present invention is not particularly limited. For example, a stationary dryer, a rotary dryer, a fluid dryer, a dryer having a stirring blade, a continuous tower dryer, etc. Can be used.

Below, the specific example of the manufacturing method of the polyethylene terephthalate resin composition of this invention is described.
For example, a polyethylene terephthalate resin composition is a process in which terephthalic acid and ethylene glycol are used as raw materials, a low polymer is obtained by direct esterification reaction, and a high molecular weight polymer is obtained by subsequent polycondensation reaction, or dimethyl terephthalate and ethylene glycol. Can be produced by a process of obtaining a low polymer by a transesterification reaction and further obtaining a high molecular weight polymer by a subsequent polymerization reaction. In the present invention, any method can be adopted. Furthermore, if necessary, a heat stabilizer, an electrostatic agent, an antifoaming agent, an antioxidant and the like can be added before and during the reaction.

As for the intrinsic viscosity of the polyethylene terephthalate resin composition, the end point of melt polymerization can be determined by the stirring torque of the polymer, and the end point determination torque of the melt polymerization apparatus may be set so that the target intrinsic viscosity is obtained.
Thereafter, the obtained molten polyethylene terephthalate is discharged from a die in a strand form, cooled, and pelletized by a cutter, whereby a liquid phase polyethylene terephthalate resin composition can be produced.
The obtained liquid phase polyethylene terephthalate resin composition is preferably pre-crystallized before solid phase polymerization. For the precrystallization, a method of applying a mechanical impact to the polyethylene terephthalate resin composition to perform a shearing treatment, a method of performing a heating treatment under hot air circulation, or the like can be used.

  The pre-crystallized polyethylene terephthalate resin composition is subsequently subjected to solid phase polymerization. The polyethylene terephthalate resin composition is charged into a solid phase polymerization apparatus and subjected to solid phase polymerization at a temperature of 200 to 230 ° C. under a reduced pressure of 6.5 to 0.013 kPa for 15 to 40 hours. Alternatively, it is charged into a solid phase polymerization apparatus, an inert gas having a moisture and oxygen concentration of 500 ppm or less is circulated, and solid phase polymerization is performed at a temperature of 200 to 230 ° C. for 15 to 40 hours. The polyethylene terephthalate resin composition after completion of solid-phase polymerization is cooled and taken out from the apparatus.

The polyethylene terephthalate resin composition of the present invention can be formed into a polyester film by the following method.
For example, after the polyethylene terephthalate resin composition is vacuum dried, it is supplied to an extruder, melted at 260 to 300 ° C., extruded into a sheet form from a T-shaped die, and a surface temperature of 10 to 60 using an electrostatic application casting method. It is wound around a mirror surface casting drum at 0 ° C. and cooled and solidified to produce an unstretched polyester film.

  The unstretched film is stretched 2.5 to 5 times in the machine direction between rolls heated to 70 to 120 ° C. At least one surface of the film may be subjected to a corona discharge treatment to apply a coating liquid or the like. Subsequently, the film is continuously stretched by 2.5 to 5 times in the width direction in a hot air zone heated at 70 to 150 ° C., subsequently led to a heat treatment zone at 200 to 240 ° C., and subjected to a heat treatment for 5 to 40 seconds. Crystal orientation is completed through a cooling zone of ~ 200 ° C. Moreover, you may perform a 3-12% relaxation process in the width direction or a longitudinal direction as needed during the said heat processing.

  The polyethylene terephthalate resin composition obtained by the present invention has a low content of cyclic trimer and a small amount of cyclic trimer when melted, good color tone, excellent transparency (haze), and film molding. Since it has a suitable intrinsic viscosity, it can be suitably used for films for IT-related applications such as display devices for liquid crystal displays and magnetic recording materials.

  The present invention will be specifically described below with reference to examples. The physical properties were measured and the effects were evaluated by the following methods.

(1) Cyclic trimer content Dissolve a sample pellet of a polyethylene terephthalate resin composition in o-chlorophenol and add an internal standard. Further, methanol was added to precipitate the polymer, and the supernatant was collected by centrifugation and quantified using a liquid chromatograph.

(2) Intrinsic viscosity The sample pellet of the polyethylene terephthalate resin composition was heated and dissolved in o-chlorophenol, and then measured at 25 ° C using an Ubbelohde viscometer.

(3) Content of antimony element, alkali metal element, alkaline earth metal element, and phosphorus element Sample pellets of polyethylene terephthalate resin composition were molded into a cylindrical shape with a melt press and measured using a fluorescent X-ray element analyzer did.

(4) Regeneration speed of cyclic trimer After vacuum drying the sample pellet of the polyethylene terephthalate resin composition at 175 ° C. for 7.5 hours, it is heated and dissolved in a nitrogen atmosphere at 300 ° C. for 30 minutes, and then returned to room temperature and solidified. Take a sample. The cyclic trimer content (A) of the sample before heat dissolution treatment and the cyclic trimer content (B) of the sample after heat dissolution treatment are quantified, and the regeneration rate of the cyclic trimer (C) from the following equation: Was calculated.

  C (wt% / min) = (B−A) / 30.

(5) Color tone b value The sample pellet of the polyethylene terephthalate resin composition was filled in a cylindrical powder measurement cell and measured by a reflection method using a color difference meter.

(6) Transparency (haze)
The sample pellet of the polyethylene terephthalate resin composition was dissolved in a mixed solvent of phenol / 1,1,2,2-tetrachloroethane (60:40 wt%) by heating, then transferred to a glass cell, and measured using a haze meter. As for the obtained transparency (haze), those with less than 0.5% were good, those with 0.5% or more and less than 1.0% were accepted, and those with 1.0% or more were rejected.

(7) Precipitation of cyclic trimer The film was cut into a size of 5 cm × 5 cm, heated in a hot air dryer at 150 ° C. for 60 minutes, and then observed on the surface of the film at 1,000 times with a scanning electron microscope. The number of precipitates of the cyclic trimer on the film surface that was arbitrarily selected and photographed was counted. As for the precipitation property of the cyclic trimer, the following standards are good (◯), those having 5 or more but less than 10 are acceptable (△), and those having 10 or more are unacceptable (x), Judged.

[Example 1]
(Esterification reaction)
An esterification reaction product, which is a reaction product of terephthalic acid and ethylene glycol, is stored in a molten state at 255 ° C. in advance, and a slurry of terephthalic acid and ethylene glycol so that the molar ratio of ethylene glycol to terephthalic acid is 1.15. Then, a constant amount was supplied while maintaining the temperature of the esterification reaction tank, and the esterification reaction was carried out while distilling water to obtain an esterification reaction product. The obtained esterification reaction product was transferred to a polymerization reaction tank.

(Melt polymerization reaction)
An ethylene glycol solution containing phosphoric acid, an ethylene glycol solution containing magnesium acetate tetrahydrate, an ethylene glycol solution containing antimony trioxide, and an ethylene glycol solution containing potassium hydroxide are separately obtained for the obtained polyethylene terephthalate resin composition. Then, an alkali metal element, an alkaline earth metal element, and a phosphorus element were added so that the M / P was 2.8 and the antimony element was 60 ppm, and the inside of the polymerization reactor was gradually reduced in pressure within 30 minutes. At the same time, the temperature was gradually raised to 280 ° C., and the polymerization reaction was carried out to the target intrinsic viscosity. Thereafter, the polycondensation reaction tank is returned to normal pressure with nitrogen gas, discharged into cold water from the base into cold water, pelletized with an extrusion cutter, pre-crystallized with a surface crystallization apparatus, and a polyethylene terephthalate resin composition is obtained. Obtained. The intrinsic viscosity of the obtained liquid phase polyethylene terephthalate resin composition was 0.50.

(Solid phase polymerization)
Polyethylene terephthalate resin composition obtained by polycondensation reaction is subjected to solid phase polymerization at a temperature of 215 ° C. for 20 hours under a reduced pressure of 0.13 kPa using a rotary vacuum dryer. I got a thing. The results are shown in Table 1. The resulting polyethylene terephthalate resin composition has an intrinsic viscosity of 0.65, a cyclic trimer content of 0.40 wt%, an antimony element content of 60 ppm, an M / P of 2.8, and a cyclic trimer. The body regeneration rate was 0.007 wt% / min, the color tone b value was 3.2, and the transparency (haze) was 0.3.

(Film forming)
The polyethylene terephthalate resin composition after the solid-phase polymerization treatment is dried at 160 ° C. for 4 hours, supplied to an extruder, melt extruded at 285 ° C., cast on a cast drum at 20 ° C. that is electrostatically applied, A stretched sheet was obtained. This unstretched sheet was stretched 3.1 times in the longitudinal direction by a stretching roll heated to 90 ° C, then stretched 3.7 times in the width direction at 120 ° C by a tenter type stretching machine, and then heat-set at 230 ° C. And wound up on a roll. The moldability of the film was good, and the precipitation property of the cyclic trimer of the obtained film was good.

[Example 2]
The same procedure as in Example 1 was performed except that the solid phase polymerization time was changed to 30 hours. The results are shown in Table 1. As for the quality of the obtained polyethylene terephthalate resin composition, the transparency (haze) was 0.4%, the film characteristics were good, and the precipitation property of the cyclic trimer of the obtained film was good.

[Example 3]
The same procedure as in Example 1 was performed except that the solid phase polymerization time was changed to 50 hours. The results are shown in Table 1. As for the quality of the obtained polyethylene terephthalate resin composition, the transparency (haze) was 0.4%, the film moldability was good, and the precipitation property of the cyclic trimer of the obtained film was good.

[Examples 4 to 7]
It implemented by the method similar to Example 1 except changing the addition amount of an antimony trioxide, potassium hydroxide, magnesium acetate tetrahydrate, and phosphoric acid. The results are shown in Table 1.

  In Example 4, the amount of antimony trioxide added was changed so that the element of antimony was 45 ppm with respect to the obtained poly (ethylene terephthalate) resin composition, and the quality of the obtained polyethylene terephthalate resin composition was transparent ( The haze was 0.2%, the film moldability was good, and the precipitation property of the cyclic trimer of the obtained film was good.

  In Example 5, the amount of antimony trioxide added was changed so that the amount of antimony element was 75 ppm with respect to the obtained poly (ethylene terephthalate) resin composition, and the quality of the obtained polyethylene terephthalate resin composition was transparent ( The haze was 0.6%, the film formability was good, and the precipitation property of the cyclic trimer of the obtained film was good.

  In Example 6, the polyethylene terephthalate resin obtained by changing the addition amount of potassium hydroxide, magnesium acetate tetrahydrate and phosphoric acid so that the M / P of the obtained polyethylene terephthalate resin composition was 2.0. As for the quality of the composition, the transparency (haze) was 0.3%, the film moldability was good, and the precipitation property of the cyclic trimer of the obtained film was good.

  In Example 7, the added amount of potassium hydroxide, magnesium acetate tetrahydrate and phosphoric acid was changed so that M / P of the obtained polyethylene terephthalate resin composition was 5.0, and the obtained polyethylene terephthalate resin As for the quality of the composition, the transparency (haze) was 0.5%, the film moldability was good, and the precipitation property of the cyclic trimer of the obtained film was good.

[Example 8]
The same procedure as in Example 1 was performed except that the intrinsic viscosity before solid phase polymerization was changed to 0.45 and the solid phase polymerization temperature was changed to 220 ° C. The results are shown in Table 1. As for the quality of the obtained polyethylene terephthalate resin composition, the transparency (haze) was 0.4%, the film moldability was good, and the precipitation property of the cyclic trimer of the obtained film was good.

[Example 9]
The same procedure as in Example 1 was performed except that the solid phase polymerization temperature was changed to 190 ° C. and the solid phase polymerization time was changed to 60 hours. The results are shown in Table 1. As for the quality of the obtained polyethylene terephthalate resin composition, the transparency (haze) was 0.4%, the film moldability was good, and the precipitation property of the cyclic trimer of the obtained film was good.

[Examples 10 to 12]
The same procedure as in Example 1 was performed except that the intrinsic viscosity before solid phase polymerization, the solid phase polymerization temperature, and the solid phase polymerization time were changed. The results are shown in Table 1.

  In Example 10, since the solid phase polymerization temperature was changed to 230 ° C. and the solid phase polymerization time was changed to 10 hours, the cyclic trimer content was 0.50 wt%. Although the precipitation of the body increased, it was within the usable range.

  In Example 11, by changing the intrinsic viscosity before solid phase polymerization to 0.35 and the solid phase polymerization temperature to 240 ° C., the color tone b value was increased to 5.0, and the regeneration rate of the cyclic trimer was increased. Since it increased to 0.011 wt%, the precipitation of the cyclic trimer increased, but it was within the usable range.

  In Example 12, since the intrinsic viscosity before solid phase polymerization was changed to 0.55 and the solid phase polymerization time was changed to 15 hours, the cyclic trimer content was changed to 0.50 wt%. Although the precipitation of the cyclic trimer increased, it was within the usable range.

[Comparative Example 1]
A film was obtained in the same manner as in Example 1 except that solid phase polymerization was not performed. The results are shown in Table 1. The precipitation property of the cyclic trimer of the obtained film was poor.

[Comparative Example 2]
It implemented by the method similar to Example 1 except changing solid phase polymerization temperature with 190 degreeC. The results are shown in Table 1. Since the intrinsic viscosity after solid-phase polymerization was as low as 0.55, the width of the extruded sheet was not constant during film formation, and the extruded sheet was very brittle and could not be stretched.

[Comparative Example 3]
The same procedure as in Example 1 was performed except that the solid phase polymerization time was changed to 225 ° C. The results are shown in Table 1. Since the intrinsic viscosity after solid-phase polymerization is as high as 0.75, deterioration of the molten polymer due to shearing heat generation in the extruder progressed, tearing occurred frequently during film forming, and the film could not be stretched.

[Comparative Example 4]
The same procedure as in Example 1 was performed except that the solid phase polymerization temperature was changed to 220 ° C. and the solid phase polymerization time was changed to 10 hours. The results are shown in Table 1. Since the cyclic trimer content was as high as 0.60 wt%, the precipitation property of the cyclic trimer of the obtained film was poor.

[Comparative Example 5]
Except for changing the amount of antimony trioxide to 20 ppm as the element of antimony with respect to the polyethylene terephthalate resin composition from which the amount of antimony trioxide added can be obtained, the same procedure as in Example 1 was performed. Because there was not, we interrupted on the way.

[Comparative Example 6]
It implemented by the method similar to Example 1 except having changed into 100 ppm as an antimony element with respect to the polyethylene terephthalate resin composition which can obtain the addition amount of an antimony trioxide. The results are shown in Table 1. Since the regeneration rate of the cyclic trimer increased to 0.015 wt% / min, the precipitation property of the cyclic trimer of the obtained film was poor.

[Comparative Example 7]
It implemented by the method similar to Example 1 except having changed the addition amount of potassium hydroxide, magnesium acetate tetrahydrate, and phosphoric acid so that M / P might be set to 1.5. The results are shown in Table 1. Since M / P was low, castability by electrostatic application was poor, and many application unevenness occurred, and a product film could not be obtained.

[Comparative Example 8]
It implemented by the method similar to Example 1 except having changed the addition amount of potassium hydroxide, magnesium acetate tetrahydrate, and phosphoric acid so that M / P might be 6.0. The results are shown in Table 1. Since the M / P was high, the cyclic trimer regeneration rate increased to 0.015 wt% / min, and the precipitation property of the cyclic trimer of the obtained film was poor.

[Comparative Example 9]
The intrinsic viscosity before solid-phase polymerization is 0.65, the addition amount of antimony trioxide is 250 ppm, and the addition amount of potassium hydroxide, magnesium acetate tetrahydrate and phosphoric acid is 1.0. The same method as in Example 1 was performed except that the change was made. The results are shown in Table 1. Polyethylene terephthalate resin composition obtained with a transparency (haze) of 1.5 has poor quality and has a high intrinsic viscosity of 0.85 after solid-phase polymerization. As the film deteriorates, tearing frequently occurs during film forming, and the film cannot be stretched.

[Comparative Example 10]
Except for changing the addition amount of antimony trioxide to 120 ppm as an antimony element, a melt polymerization reaction is performed in the same manner as in Example 1 to obtain a liquid phase polyethylene terephthalate resin composition having an intrinsic viscosity of 0.65, and then rotating. A heat treatment was carried out at a temperature of 230 ° C. for 20 hours in a nitrogen gas atmosphere to obtain a polyethylene terephthalate resin composition. The results are shown in Table 1. The quality of the obtained polyethylene terephthalate resin composition having a transparency (haze) of 1.0 was poor, and the precipitation property of the cyclic trimer of the obtained film was also poor.

Claims (4)

  The content of cyclic trimer is 0.50 wt% or less, the intrinsic viscosity is 0.60 to 0.70, the content of antimony element is 40 to 80 ppm, and the alkali metal element and alkaline earth contained in the polyethylene terephthalate resin A polyethylene terephthalate resin composition having a molar ratio of metal element to phosphorus element (M / P) of 2.0 to 5.4.   The polyethylene terephthalate resin composition according to claim 1, wherein the regeneration rate of the cyclic trimer when melted at 300 ° C is 0.010 wt% / min or less.   The polyethylene terephthalate resin composition according to claim 1, wherein a color tone b value in the color difference meter is 4.0 or less.   The polyethylene terephthalate resin according to any one of claims 1 to 3, wherein the polyethylene terephthalate resin composition having an intrinsic viscosity of 0.40 to 0.52 is solid-phase polymerized at a temperature of 200 to 230 ° C for 15 to 40 hours. A method for producing the composition.