JP6217470B2 - Method for producing polyethylene terephthalate resin composition - Google Patents

Description

  The present invention relates to a polyethylene terephthalate resin composition and a method for producing the same. Specifically, the present invention relates to a method for producing a polyethylene terephthalate resin composition that is clean and excellent in color tone and particularly suitable for film applications such as transparent optics, by using a specific antimony compound as a polymerization catalyst for the polycondensation reaction.

Polyester, especially polyethylene terephthalate, is widely used for fibers, films and bottles due to its excellent properties.
Industrial production methods for polyethylene terephthalate resin compositions include direct polymerization of terephthalic acid and ethylene glycol, followed by polycondensation, and transesterification of dimethyl terephthalate and ethylene glycol. A transesterification method in which polycondensation is performed is widely adopted.

Conventionally, when producing a polyethylene terephthalate resin composition, an antimony compound such as antimony trioxide or antimony acetate has been used as a polycondensation reaction catalyst.
At this time, Patent Document 1 discloses that the content of bismuth element and selenium element in antimony trioxide, which is an antimony compound, is within a certain range, thereby improving the color tone of the polyethylene terephthalate, black foreign matter, and foreign matter in the die during film formation. However, the further transparency, low haze, low minute foreign matter, and heat resistance required for, for example, a transparent optical film are insufficient. In addition, Patent Document 2 uses antimony oxide as a flame retardant aid and describes the effect of improving flame retardancy and metal corrosivity by setting the sulfate content to a specific range or less. However, it did not satisfy the required characteristics required for the current transparent optical film.

JP-A-3-215522 JP-A-4-20259

  The object of the present invention is to solve the above-mentioned conventional problems, and in recent years, transparency optical films and the like have become more and more demanding characteristics, transparency, low haze, low minute foreign matter, heat-resistant polyethylene terephthalate resin composition To provide things.

  An object of the present invention described above is to provide a polyethylene terephthalate resin by performing a polycondensation reaction after an esterification reaction or an ester exchange reaction using terephthalic acid or an acid component mainly composed thereof and ethylene glycol or a glycol component mainly composed thereof. The production of the composition is accomplished by a method for producing a polyethylene terephthalate resin composition comprising using an antimony compound containing 0.1 to 100 ppm of sulfur element and 70 to 200 ppm of lead element as a polycondensation catalyst.

The polyethylene terephthalate resin composition obtained in the present invention is excellent in transparency, low haze, low minute foreign matter and heat resistance, and can be preferably used for a transparent optical film.

In the polyethylene terephthalate resin composition of the present invention, the main carboxylic acid component is a terephthalic acid unit (hereinafter referred to as TPA), and the main glycol unit is an ethylene glycol (hereinafter referred to as EG) unit.
In the method for producing a polyethylene terephthalate resin composition of the present invention, for example, a transesterification method in which dimethyl terephthalate and ethylene glycol are subjected to a transcondensation reaction followed by a polycondensation reaction, or a polycondensation after an esterification reaction between terephthalic acid and ethylene glycol. Any of the direct polymerization methods to be reacted can be employed.

  Moreover, in the manufacturing method of the polyethylene terephthalate resin composition in this invention, if it is 20 mol% or less of a dicarboxylic acid component, it can contain the 1 type (s) or 2 or more types of dicarboxylic acid units other than a TPA unit, and the same If it is 20 mol% or less of a glycol unit, 1 type (s) or 2 or more types of glycol units other than EG unit can be included.

  Examples of dicarboxylic acid units other than TPA units include aromatic dicarboxylic acids such as isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenoxyethanedicarboxylic acid; dodecanedioic acid, adipic acid, sebacic acid, azelaic acid, decanedicarboxylic acid. Examples thereof include aliphatic carboxylic acids such as acids; alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid; and hydroxycarboxylic acid units such as hydroxybenzoic acid, glycolic acid, and hydroxyethoxybenzoic acid.

Examples of the glycol unit other than the EG unit include propylene glycol, butanediol, diethylene glycol, hexamethylene glycol, p-xylene glycol, 1,4-cyclohexadimethanol, and bisphenol.
Furthermore, a polyester obtained by copolymerizing a trifunctional or higher functional compound may be used as long as the thermoplasticity is not impaired.

  The production method of the polyethylene terephthalate resin composition in the present invention needs to use an antimony compound containing a specific amount of sulfur element and lead element as a catalyst. The antimony compound is preferably used as an EG solution from the viewpoint of preventing generation of coarsening due to antimony aggregation in the polycondensation reaction system.

In addition, the antimony compound is added before the polycondensation reaction in the direct polymerization method, and before the transesterification reaction in the transesterification method, and is transparent without aggregation of antimony metal or the like in the obtained polyethylene terephthalate resin composition. Is desirable.
The addition amount of the antimony compound is preferably 10 ppm or more and 1000 ppm or less with respect to the obtained polyethylene terephthalate resin composition. If the addition amount is 10 ppm or more, the polycondensation reaction proceeds and a polyethylene terephthalate resin composition having a predetermined intrinsic viscosity can be obtained. Moreover, if it is 1000 ppm or less, the heat resistance and color tone of the obtained polyethylene terephthalate resin composition will not be yellowish, and the dissolved antimony element will be insolubilized and transparency will not be lowered. When it is 40 or more and 500 ppm or less, the polycondensation reactivity and the transparency and color tone of the obtained polyethylene terephthalate resin composition are improved, which is particularly preferable.

  A feature of the present invention is to obtain a polyethylene terephthalate resin composition having a clean and good color tone by the amount of sulfur element and lead element contained in the antimony compound used as the polycondensation catalyst within a specific range.

First, specific examples of the compound contained as the elemental sulfur in the antimony compound include sulfates, sulfides and oxides, but sulfates are preferable from the viewpoint of productivity.
Further, the content of elemental sulfur is required to be 0.1 to 100 ppm with respect to the antimony compound. From the viewpoint of color tone, it is preferably 10 to 90 ppm, more preferably 20 to 60 ppm. When the amount of sulfur element is less than 0.1 ppm, the transparency of the obtained polyethylene terephthalate resin composition is undesirably lowered. Moreover, when the amount of sulfur elements exceeds 100 ppm, the color tone of the obtained polyethylene terephthalate resin composition deteriorates, which is not preferable.

Specific examples of the compound contained as the lead element in the antimony compound include oxides, chlorides, sulfides and sulfates, but oxides are preferable from the viewpoint of productivity.
Here, the content of the lead element needs to be 70 to 200 ppm with respect to the antimony compound. From the viewpoint of transparency, it is preferably 130 to 190 ppm, more preferably 140 to 180 ppm. If the amount of lead element is less than 70 ppm, the transparency of the obtained polyethylene terephthalate resin composition is undesirably low. Moreover, when the amount of lead elements exceeds 200 ppm, the color tone of the obtained polyethylene terephthalate resin composition deteriorates, which is not preferable.
The reason for using an antimony compound containing a specific amount of elemental sulfur and lead as a polymerization catalyst in the present invention is that the elemental sulfur and element lead to a nucleating effect and sufficiently control the growth of the particle size of antimony metal. Therefore, it is estimated that the light diffusion can be controlled.

  That is, the polyethylene terephthalate resin composition which is the object of the present invention can be produced only by using an antimony compound that simultaneously satisfies the two conditions of sulfur element content and lead element content as a polymerization catalyst.

Here, the antimony compound is preferably dissolved in EG or glycol mainly composed of EG by heating and used as a 1.5 to 2.5 wt% glycol solution. From the viewpoint of productivity, it is preferably 1.7 to 2.3 wt%, more preferably 1.9 to 2.1 wt%. When the concentration of the antimony compound is 1.5 wt% or more, the amount of the polyethylene terephthalate resin composition obtained is good because the amount added as a glycol solution is appropriate. Further, if the concentration of the antimony compound is 2.5 wt% or less, it is preferable that aggregation of the metal antimony is less likely to occur.
The pH of the glycol solution is preferably from 3.0 to 7.0. From the viewpoint of reducing properties of the metal antimony, it is preferably 3.5 to 6.5, more preferably 4.0 to 6.0. Within this range, the metal antimony reducing properties are effectively expressed, and the transparency and color tone of the polyethylene terephthalate resin composition are improved.

  The material of the equipment such as the inner wall of the polymerization can in the present invention preferably contains iron, chromium and manganese, but a metal material containing no nickel is preferred. If nickel-containing material is used, metal antimony is precipitated in the polycondensation reaction system and becomes a foreign substance in the obtained polyethylene terephthalate resin composition, which is not preferable because the transparency of the resin is lowered.

The antimony compound used as a polymerization catalyst in the present invention specifically employs the following production method.
For example, there is a method in which antimony trioxide is precipitated by heating and dissolving metal antimony obtained by electrolytic refining antimony ore, then blowing oxygen to perform primary oxidation and sublimation, and further reacting with oxygen. In addition, as a method of adding elemental sulfur to antimony trioxide, when the above metal antimony and elemental sulfur are heated, the elemental sulfur burns to form sulfur dioxide, which is adsorbed and absorbed on the surface of the solid antimony particles to obtain sulfate. There are methods. Further, there is a method of obtaining lead oxide by heating and dissolving the metal antimony and the lead element, and then blowing and oxidizing oxygen.

  A conventionally well-known manufacturing method is employable as the manufacturing method of the polyester resin composition in this invention. For example, bis-β-hydroxyethyl terephthalate (hereinafter referred to as BHT), which is a reaction product of TPA and EG, is previously stored in a molten state at 255 ° C., and a slurry comprising TPA and EG is provided separately from the reaction vessel. It prepares in a tank, water is distilled off while carrying out fixed quantity supply, maintaining the temperature of a reaction tank, and it is made to esterify. After 4 to 5 hours from the start of the reaction, the esterification is completed, the reaction product BHT is transferred to a polycondensation reaction tank, and antimony trioxide and other additives are added. Thereafter, the pressure is reduced until a high vacuum is reached, and the polycondensation reaction is performed by heating and raising the temperature to about 290 ° C. until the target intrinsic viscosity is reached. After completion of the reaction, the polymer is discharged and cooled in cold water from a polymer discharge nozzle provided at the bottom of the polycondensation reaction tank, and pelletized by a cutter. Alternatively, in order to proceed the transesterification reaction using dimethyl terephthalate and EG as raw materials, antimony trioxide and other additives are added first, and the temperature is raised to 230 ° C. over 3 to 4 hours, and methanol is distilled. And transesterification. The reaction product BHT is transferred to a polycondensation reaction tank, and antimony trioxide and other additives are added. Thereafter, the pressure is reduced until a high vacuum is reached, and the polycondensation reaction is performed by heating and raising the temperature to about 290 ° C. until the target intrinsic viscosity is reached. After completion of the reaction, the polymer is discharged and cooled in cold water from a polymer discharge nozzle provided at the bottom of the polycondensation reaction tank, and pelletized by a cutter.

  The polyethylene terephthalate resin composition obtained by the method of the present invention is excellent in transparency, low haze, low minute foreign matter, and heat resistance, and when used as a film, it is useful in the field of transparent optics.

The present invention will be described more specifically with reference to the following examples.
In addition, the measuring method of a physical property and the evaluation method of an effect were performed in accordance with the following method.

(1) Amount of lead element in antimony compound Measured with an ICP emission analyzer (OPTIMA 4300DV, manufactured by Perkin Elmer).

(2) Amount of sulfur element in antimony compound The amount of sulfur element was calculated from the value measured as SO4 by ion chromatography.

(3) The color difference meter of the polyethylene terephthalate resin composition (SM color computer (SM-T), manufactured by Suga Test Instruments Co., Ltd.) was used to measure by a reflection method. The b value (yellowishness) of the obtained color tone is preferably less than 5.0, and more preferably less than 4.5. Further, the L value (whiteness) of the obtained color tone is preferably 45 or more, and more preferably 60 or more.

(4) Haze (transparency) of polyethylene terephthalate resin composition
0.5 g of polyethylene terephthalate was dissolved in 20 ml of a mixed solvent of phenol / ethane tetrachloride (6/4 weight ratio) by stirring at 100 ° C. for 60 minutes. After cooling to room temperature, the solution was placed in a 20 mm glass cell, Measured with a Haze computer (HGM-2DP) manufactured by Suga Test Instruments. With respect to the obtained transparency, those with less than 1.1% are very good, those with 1.1 or more and less than 1.5% are good, those with 1.5 or more and less than 2.4% are acceptable, and 2. 4% or more was rejected.

(5) The number of foreign matters in the polyethylene terephthalate resin composition The foreign matters in the polyester of 300 g of the sample to be measured were visually observed to confirm the number.
Also, 1 g of the sample to be measured is dissolved in 20 ml of a solution of phenol / 1,1,2,2, tetrachloroethane = 60/40, filtered through a filter paper, and black foreign matter (17 μm or more on the filter paper surface with a stereo microscope (60 times)) ).

(6) Gelation rate of polyethylene terephthalate resin composition 1 g of a polyethylene terephthalate resin composition was freeze-pulverized to form a powder having a diameter of 300 μm or less and vacuum-dried. This sample is heat-treated in an oven at 300 ° C. for 7 hours in the air. This is dissolved in 50 ml of orthochlorophenol (OCP) by heating at a temperature of 80 to 150 ° C. for 0.5 hour. Subsequently, it is filtered through a Buchner type glass filter (maximum pore size 20-30 μm), washed and vacuum dried. The weight of the OCP insoluble matter remaining on the filter is calculated from the increase in the weight of the filter before and after the filtration, and the weight fraction of the OCP insoluble matter with respect to the polyester resin composition weight (1 g) is obtained. did.

[Example 1]
46.4 parts by weight of bis-β-hydroxyethyl terephthalate (hereinafter referred to as “BHT”), which is a reaction product of terephthalic acid and ethylene glycol, consisting of 41.1 parts by weight of terephthalic acid was previously stored in a molten state at 255 ° C. A slurry consisting of 45.3 parts by weight of acid and 19.5 parts by weight of ethylene glycol was prepared in a separate mixing tank, and water was distilled off while conducting a constant amount supply while maintaining the temperature of the reaction tank to cause esterification. After 4 hours and 40 minutes from the start of the reaction, the esterification was completed, BHT as this reaction product was transferred to a polycondensation reaction tank, and 0.0218 parts by weight of triethylphosphonoacetate was added. Subsequently, 0.06 parts by weight of magnesium acetate, 0.0006 parts by weight of potassium hydroxide, 23 ppm of an antimony compound containing 40 ppm of sulfur element and 160 ppm of lead element are added, and the pressure is reduced to 290 ° C. until a high vacuum is reached in 40 minutes. The polycondensation reaction was performed by heating and raising the temperature until the target intrinsic viscosity was reached. After completion of the reaction, strands were discharged into cold water from the die at the bottom of the polycondensation reaction tank, and cylindrical pellets were formed by an extrusion cutter. The quality of the obtained polyethylene terephthalate resin composition was good with a color tone b value of 4.0 and a haze of 0.3%. The results are shown in Table 2.

[Examples 2 to 5]
It implemented by the method similar to Example 1 except having made sulfur element content and lead element content in the antimony compound to add into Table 1. FIG. The quality of the obtained polyethylene terephthalate resin composition was good with a color tone b value of 3.0 to 5.0 and a haze of 0.3 to 0.6%. The results are shown in Table 2.

[Example 6]
It implemented by the method similar to Example 1 except having added the sulfur element in the antimony compound to add as sulfide. The quality of the obtained polyethylene terephthalate resin composition was good with a color tone b value of 4.0 and a haze of 0.3%. The results are shown in Table 2.

[Example 7]
It implemented by the method similar to Example 1 except having added the lead element in the antimony compound to add as a chloride. The quality of the obtained polyethylene terephthalate resin composition was good with a color tone b value of 4.0 and a haze of 0.3%. The results are shown in Table 2.

[Examples 8 to 11]
The same procedure as in Example 1 was performed except that the concentration of the antimony compound added as the glycol solution and the pH of the glycol solution were changed to Table 1. The quality of the obtained polyethylene terephthalate resin composition was good with a color tone b value of 3.0 to 5.0 and a haze of 0.3 to 0.5%. The results are shown in Table 2.

[Comparative Examples 1-4]
It implemented by the method similar to Example 1 except having made sulfur element content and lead element content in the antimony compound to add into Table 1. FIG. The quality of the obtained polyethylene terephthalate resin composition was poor, with a color tone of 3.0 to 6.0 and a haze of 0.2 to 2.0%. The results are shown in Table 2.

Claims (4)

In producing a polyethylene terephthalate resin composition by performing an esterification reaction or a transesterification reaction using terephthalic acid or an acid component mainly composed thereof and ethylene glycol or a glycol component mainly composed thereof, followed by polycondensation reaction. A method for producing a polyethylene terephthalate resin composition, comprising using an antimony compound containing 0.1 to 100 ppm of sulfur element and 70 to 200 ppm of lead element as a condensation catalyst. The method for producing a polyethylene terephthalate resin composition according to claim 1, wherein the sulfur element is a sulfate. The method for producing a polyethylene terephthalate resin composition according to claim 1 or 2, wherein the lead element is an oxide. An antimony compound is heated and dissolved in ethylene glycol or a glycol mainly composed of ethylene glycol to form a 1.5 to 2.5 wt% glycol solution, and the glycol solution is added at a pH of 3.0 to 7.0. The method for producing a polyethylene terephthalate resin composition according to any one of claims 1 to 3.