JP2014141591A - Hydrolysis resistant polyester composition and production method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyester composition which allows easy reduction of the amount of terminal carboxyl groups, an important quality item for hydrolysis resistance, suppresses occurrence of surface defects due to bubbles in film formation and is useful for e.g. the back sheet of solar cells, and to provide its production method.SOLUTION: A hydrolysis resistant polyester composition comprises an aromatic dicarboxylic acid as the main acid component and ethylene glycol as the main glycol component, and contains oxalic acid glycol ester (PEO) by an amount of 0.1-5.0 mol% relative to the amount of all acid components and a porous powder having pore sizes of 4Å or greater by an amount of 0.1-5 wt.%.

Description

  The present invention contains a specific oxalic acid glycol ester, which is excellent in hydrolysis resistance but easy to handle after the polycondensation reaction step with few bubbles in the polymer (suppresses strand breakage during polymer discharge operation) The present invention relates to a polyester composition having excellent resistance and a method for producing the same.

  Polyesters, especially polyethylene terephthalate, have been widely used because of their excellent productivity, mechanical properties, thermal properties, electrical properties, chemical properties and dimensional stability. However, when most polyesters are used in a high-temperature and high-humidity environment, there is a problem that the physical performance tends to deteriorate due to hydrolysis and the use period and use conditions are limited.

  Various proposals have conventionally been made to improve the hydrolysis resistance of polyester. For example, Japanese Patent Publication No. 48-35953 describes a method of adding a glycol ester of oxalic acid and / or an oxalic acid-based polyester. However, although this method shows an improvement in hydrolysis resistance, bubbles are often present in the polymer, which is not preferable for film applications.

  Japanese Patent Laid-Open No. 6-263850 describes a method in which a glycol ester of oxalic acid and / or a low-polymerization degree oligomer containing oxalic acid as an acid component is added to polybutylene naphthalate. Is not preferable for film applications. JP-A-8-208816 proposes to add oxalic acid as it is for the purpose of omitting the oxalic acid glycol ester synthesis step, but bubbles are not taken into consideration.

  Japanese Patent Application Laid-Open No. 2002-187965 discloses a polyester film to which a carbodiimide compound or a monomer or polymer of an oxazoline compound is added as a hydrolysis-resistant agent. However, a film containing a carbodiimide compound or the like generates a gas due to isocyanate and other by-products and decomposition products in the production process and use, and this gas generates a bad odor, which deteriorates the environment of the production site. It was. Further, when these hydrolysis-resistant agents are used, the viscosity of the polymer increases, and instability of extrusion and problems that are difficult to control occur in the extrusion process.

Japanese Patent Publication No. 48-35953 JP-A-6-263850 JP-A-8-208816 JP 2002-187965 A

  The object of the present invention is to easily reduce the amount of terminal carboxyl groups, which is an important quality item for hydrolysis resistance, and to reduce surface defects due to bubbles when formed into a film, which is useful, for example, for solar cell backsheets. It is providing the polyester composition and its manufacturing method.

In order to achieve the above object, the present inventors have intensively studied that even when a glycol ester of oxalic acid is added, the content of bubbles in the polyester is small and the amount of terminal carboxyl groups is reduced.
As a result, when glycolic ester of oxalic acid is added in the presence of a porous powder having a specific pore size, the amount of terminal carboxyl groups is surprisingly reduced while the bubble content in the polyester is also reduced. We have found out that we can do it and have reached the present invention.

（２）多孔質粉体がゼオライトである上記（１）記載の耐加水分解性ポリエステル組成物。
（３）芳香族ジカルボン酸を主たる酸成分とし、エキレングリコールを主たるグリコール成分とするポリエステル組成物の製造法において、重縮合反応時に上記式（１）で示されるシュウ酸グリコールエステル（以下、ＰＥＯと略す）を、ポリエステルの全酸成分に対して０．１〜５．０ｍｏｌ％（但し、該シュウ酸エステルがｎ＝１以上のものにあっては、その繰返し単位を１モルとみなす）の範囲で添加する際に工程と、４Å以上の細孔径を有する多孔質粉体を、得られるポリエステル組成物の重量を基準として、０．１〜５重量％の範囲で添加する工程とを有す存在させるポリエステル組成物の製造方法。
（４）多孔質紛体の添加後もしくは多孔質紛体と一緒に、該シュウ酸グリコールエステルを添加する上記（３）記載のポリエステル組成物の製造方法。
（５）シュウ酸グリコールエステルの合成反応中に、多孔質紛体をシュウ酸グリコールに添加する上記（４）記載のポリエステル組成物の製造方法。 Thus, according to the present invention, the following polyester compositions (1) and (2) and a method for producing the polyester composition (3) are provided.
(1) A polyester composition comprising an aromatic dicarboxylic acid as a main acid component and ethylene glycol as a main glycol component, wherein all of the oxalic acid glycol ester (hereinafter abbreviated as PEO) represented by the following formula (1) A hydrolysis-resistant polyester composition containing 0.1 to 5.0 mol% of a porous powder having a pore diameter of 4 to 4% or more with respect to the acid component.

(2) The hydrolysis-resistant polyester composition according to the above (1), wherein the porous powder is zeolite.
(3) In a process for producing a polyester composition having an aromatic dicarboxylic acid as a main acid component and an ethylene glycol as a main glycol component, an oxalic acid glycol ester (hereinafter referred to as PEO) represented by the above formula (1) during the polycondensation reaction. Of 0.1 to 5.0 mol% of the total acid component of the polyester (provided that the oxalate ester has n = 1 or more, the repeating unit is regarded as 1 mol). And a step of adding a porous powder having a pore size of 4 mm or more in a range of 0.1 to 5% by weight based on the weight of the obtained polyester composition. A method for producing a polyester composition to be present.
(4) The method for producing a polyester composition according to (3), wherein the oxalic acid glycol ester is added after the porous powder is added or together with the porous powder.
(5) The method for producing a polyester composition according to (4), wherein the porous powder is added to glycol oxalate during the synthesis reaction of the oxalic acid glycol ester.

  According to the present invention, by examining the PEO addition conditions, it is possible to provide a polyester chip with less bubbles in the polyester and having good hydrolysis resistance without impairing productivity.

  According to the present invention, it is possible to suppress bubbles in the polymer while improving hydrolysis resistance by including a specific oxalic acid polyester and / or a glycol ester of oxalic acid in the polyester, for example, It is excellent in handleability after the polymerization process (suppressing strand breakage during polymer discharge operation) and quality when made into a film.

  The polyester in the present invention is a polyester having an aromatic dicarboxylic acid as a main acid component and ethylene glycol as a glycol component. Such polyesters are substantially linear and have film-forming properties, particularly film-forming properties by melt molding. Examples of the aromatic dicarboxylic acid include terephthalic acid, naphthalene dicarboxylic acid, isophthalic acid, diphenyl ketone dicarboxylic acid, and anthracene dicarboxylic acid.

  Among these, in the present invention, those having ethylene terephthalate or ethylene naphthalate as the main constituent are preferable, and particularly, including polyethylene terephthalate and polyethylene-2,6-naphthalenedicarboxylate, for example, 80 of all dicarboxylic acid components. Preference is given to homopolymers and copolymers in which the mol% or more is terephthalic acid or 2,6-naphthalenedicarboxylic acid.

  In the case of a polyester in which ethylene terephthalate or ethylene naphthalene dicarboxylate is the main repeating unit, 20 mol% or less of the total acid component is terephthalic acid and / or 2,6 as long as the surface flatness and dry heat deterioration are not impaired. -The above-mentioned aromatic dicarboxylic acids other than naphthalenedicarboxylic acid, and aliphatic dicarboxylic acids such as adipic acid and sebacic acid, aliphatic dicarboxylic acids such as cyclohexane-1,4-dicarboxylic acid, etc. Can be. Further, in the polyester of the present invention, a component derived from an oxycarboxylic acid such as an aromatic oxyacid such as hydroxybenzoic acid or an aliphatic oxyacid such as ω-hydroxycaproic acid, unless the effects of the present invention are impaired. Those which are copolymerized or bonded at 20 mol% or less with respect to the total amount of the dicarboxylic acid component and the oxycarboxylic acid component are also included. Furthermore, the polyester in the present invention is in an amount in a range that is substantially linear, and unless the effects of the present invention are impaired, for example, an amount of 2 mol% or less with respect to the total acid component is a trifunctional or higher polycarboxylic acid. Acid or polyhydroxy compounds such as those obtained by copolymerization of trimellitic acid, pentaerythritol and the like are also included.

  The polyester in the present invention can be produced by a polycondensation reaction via a per se known esterification reaction or transesterification reaction. In the case of passing through the transesterification reaction, preferred examples of the transesterification reaction catalyst used in the production thereof include calcium compounds, magnesium compounds, manganese compounds, and titanium compounds. Further, in the present invention, a trace amount of an alkali metal compound such as potassium hydroxide is added in order to further reduce the number of carboxylic acid terminal groups of the obtained polyester before the esterification reaction or transesterification reaction is started. May be. Furthermore, in the present invention, a small amount of a magnesium compound such as magnesium acetate may be added between the end of the esterification reaction or transesterification reaction and the beginning of the polycondensation reaction in order to improve the electrostatic application characteristics. .

  The precursor thus obtained through the transesterification reaction is subjected to a polycondensation reaction in a molten state. At this time, the phosphorus compound is added by the initial stage of the polycondensation reaction, preferably during the polycondensation reaction after the end of the esterification reaction or the end of the transesterification reaction until the intrinsic viscosity becomes 0.3 dl / g. The phosphorus compound is not particularly limited, but is selected from the group consisting of phenylphosphonic acid, phosphonic acid compounds, phosphinic acid compounds, phosphine oxide compounds, phosphonous acid compounds, phosphinic acid compounds, and phosphine compounds. The use of one or two or more compounds is preferable because the effect of improving the catalytic activity is great. Of these, phenylphosphonic acid is particularly preferred from the viewpoint of maintaining reaction activity even at low temperatures during the polycondensation reaction.

  Furthermore, in the polyester of the present invention, additives such as lubricants, pigments, dyes, antioxidants, light stabilizers, light-shielding agents (for example, carbon black, titanium oxide, etc.) are within the range that does not impair the effects of the present invention. Can be contained as required.

The glycol ester (PEO) of oxalic acid in the present invention is represented by the formula (1).
PEO is produced from oxalic acid or an ester-forming derivative thereof and an aliphatic diol by a generally well-known polycondensation reaction (preferably melt polymerization). For example, it can be produced by filling the oxalic acid or its ester-forming derivative and an aliphatic diol together with a catalyst into a reactor for polycondensation. As the catalyst, compounds such as P, Ti, Ge, Zn, Fe, Sn, Mn, Co, Zr, V, Ir, La, Ce, Li, Ca, and Hf are preferable. In the polycondensation reaction, a heat-resistant agent may be added if necessary to prevent thermal degradation. Moreover, a catalyst deactivator such as a phosphoric acid ester compound (such as a phosphoric acid ester) can be added after completion of the reaction.

  In the present invention, the mechanism of reducing the concentration of the terminal carboxyl group by PEO is due to the reaction of the terminal carboxyl group of the polyester and polyazalate, and the alkylene group in the above formula (1) is incorporated into the polyester main chain. It is preferable that it is the same ethylene group as the main glycol component which comprises polyester, on suppressing the fall of melting | fusing point and a crystallinity fall. The PEO used in the present invention is preferably a monomer or a low polymer in which 1 to 4 repeating units represented by the above formula are connected on average. When the average number of linked repeating units exceeds the upper limit, the melting point of PEO itself becomes high and handling becomes difficult. About the addition amount of PEO, it is necessary for it to be 0.1-5.0 mol% by the number-of-moles of the repeating unit of the said Formula (1) with respect to all the acid components which form polyester, Especially, it is 0.8. 5-3.0 mol% is preferable, and 0.7-1.7 mol% is especially preferable. If the amount added is less than this lower limit, a polyester having a sufficiently low number of carboxylic acid end groups cannot be obtained. On the other hand, if the amount added is too large, the inherent viscosity after addition is greatly reduced and significant foaming occurs, causing trouble in the reaction process. Or surface defects due to air bubbles are likely to occur when a film is formed.

  In the present invention, a porous powder having a pore diameter of 4 mm or more is added to the polyester. The method for adding the porous powder is not particularly limited, and for example, it may be added at the stage of PEO synthesis, added during the polyester synthesis reaction, or added after the polyester is synthesized, pelletized, and remelted. Preferably, the porous powder is preferably present when PEO is added. If the PEO addition time is the polycondensation reaction time during polyester synthesis, the porous powder is added to the system before that. It is preferable to do. More preferably, it is added at the time of PEO synthesis. In this way, PEO and the porous powder are inevitably charged at the same time, and the PEO component adheres to or impregnates the powder, so that carbon dioxide generated from PEO is adsorbed or finely dispersed. Is more expressed.

  The porous powder in the present invention may be an inorganic body and / or an organic body as long as it has a pore diameter of 4 mm or more. For example, zeolite, molecular sieves, hydrotalcite compound particles, silicic acid-coated hydrotalcite Compound particles, polymer metal complexes, activated carbon, etc. can be raised. Among these, zeolite that can be obtained at a relatively low cost and whose pore diameter and pore volume are easily controlled is preferable. If the pore diameter is 4 mm or more, the upper limit is not limited, and an effect is observed for adsorption and fine dispersion of carbon dioxide gas generated from PEO. A preferable pore diameter is 4 to 20 mm, and further 5 to 12 mm. The porous powder may be modified to the powder surface for the purpose of suppressing the activity when added to the polyester and / or improving the dispersibility, so long as the effect of the present invention is not impaired. Silane compound treatment to improve the affinity of powder in polyester, high silica zeolite that increases the proportion of silicon oxide in the component and promotes adsorption of nonpolar substances, alumina and silica surface treatment to improve dispersibility Etc. The pore volume of the porous powder in the present invention is preferably in the range of 0.10 to 2.50 (ml / g), and more preferably in the range of 0.45 to 0.70 (ml / g).

  The ratio of the porous powder in the polyester composition is in the range of 0.1 to 5% by weight based on the weight of the obtained polyester composition. A preferable content of the porous powder is 0.2 to 2% by weight. When the content is less than the lower limit, there is no effect of suppressing bubbles, and when the content exceeds the upper limit, the intrinsic viscosity of the polyester tends to decrease due to the activity of the porous powder.

Below, the manufacturing method of the polyester composition of this invention is demonstrated in detail.
As described above, the method for producing the polyester composition of the present invention uses an aromatic dicarboxylic acid as a main acid component, an ethylene glycol as a main glycol component, and an oxalic acid glycol ester represented by the above formula (1) as a polyester. A step of adding in the range of 0.1 to 5.0 mol% with respect to the total acid component and a porous powder having a pore diameter of 4 mm or more, based on the weight of the obtained polyester composition, 0.1 to And adding in the range of 5% by weight.

  The preferred addition time of PEO in the present invention is preferably after the intrinsic viscosity of the polyester is 0.2 dl / g or more, particularly 0.4 dl / g or more. When the intrinsic viscosity at the time of adding PEO is less than the lower limit, the terminal carboxyl group itself in the polyester is small, so that the effect of reducing the amount of the terminal carboxyl group is small. It is also effective to add PEO in two or more divided portions. For example, it is preferable to add 50 to 90% of the total amount of PEO charged when the intrinsic viscosity is 0.2 to 0.3 dl / g, and to add the remaining 10 to 50% when the intrinsic viscosity is 0.4 dl / g or more. . The reason for this is that although the terminal carboxyl group in the polyester is lowered by the addition of PEO, the terminal carboxyl group also starts to increase more or less over time after the polycondensation reaction after the addition. And it is because it is possible to suppress the carboxyl group terminal to be regenerated by dividing and introducing in this way.

  The intrinsic viscosity of the polyester obtained by the method for producing a polyester composition of the present invention is preferably 0.60 dl / g or more, and more preferably in the range of 0.60 to 0.85 dl / g. When the intrinsic viscosity is less than the lower limit, it is difficult to impart sufficient mechanical properties to the resulting film, while when the upper limit is exceeded, the load on the melt extrusion equipment is large due to the high melt viscosity, resulting in a higher temperature than the result. Therefore, the amount of terminal carboxyl groups of the resulting film is likely to increase. Further, the intrinsic viscosity at the completion of the polycondensation reaction is preferably in the range of 0.60 to 0.75 dl / g because the polycondensation reaction time can be relatively short.

  The number of carboxylic acid end groups of the polyester obtained by the method for producing a polyester composition of the present invention is preferably 12 eq / t or less, more preferably 8 eq / t or less, particularly 6 eq / t or less, from the viewpoint of hydrolysis resistance. More preferably. Although a minimum in particular is not restrict | limited, From points, such as productivity, it is 3 eq / t or more. The amount of DEG of the polyester obtained by the method for producing a polyester composition of the present invention is preferably 1.3% by weight or less, more preferably 1.2% by weight or less, and particularly preferably 1.0% by weight or less. If it exceeds 1.3% by weight, the reason is not clear, but the durability after film formation may be inferior.

  In order to make the present invention more effective, the polycondensation reaction is preferably carried out at a temperature in the range from the melting point of the resulting polyester to the melting point + 20 ° C., more preferably in the range of the melting point to the melting point + 10 ° C. For example, polyethylene terephthalate usually undergoes a polycondensation reaction at 280 to 300 ° C. However, since PEO-added polyethylene terephthalate has a polycondensation reaction promoting effect, the polycondensation reaction rate is maintained even at low temperatures, while the number of carboxylic acid end groups is increased Can be reduced. In polyethylene terephthalate, 268-275 degreeC is preferable, and also 269-272 degreeC is preferable.

  The method for producing a polyester composition of the present invention can also be a polyester composition having a small amount of oligomers by further solid-phase polymerization. A method known per se for solid phase polymerization can be suitably used, and is not particularly limited. For example, the polyester composition in a solid state may be retained and polymerized at a temperature of 150 to 250 ° C. under a vacuum or a nitrogen stream until a desired intrinsic viscosity is obtained. For example, as a method of making a polyester composition into chips and retaining them under the above-mentioned conditions, for example, a method of retaining them in a rotating sealed reaction vessel, a method of continuously forming chips in a reaction tank having a certain volume. Examples thereof include a method in which the polyester composition is retained for an arbitrary time while being moved.

  As described above, the polyester composition of the present invention may be used in a chip state. And when the bubbles contained in the state of the chip are seen, the polyester composition of the present invention has a bubble content of 1 mm or more in diameter of 500 / less, further 250 or less, particularly 100 or less, per 25 g of chip. Most preferably, it is 50 or less. When the bubble content is greater than the upper limit, when the film is used, surface defects due to bubbles are likely to occur. The number of bubbles can be adjusted by the above-described method for producing the polyester composition of the present invention, and the addition time and amount of PEO, and the type, addition amount, and addition time of the porous powder.

  The polyester composition of the present invention thus obtained can be suitably used for a film, and can be suitably used for a film for a solar battery backsheet, in particular, since it has excellent hydrolysis resistance but has few surface defects. .

  It should be noted that the polyester chip of the present invention has a range that does not impair the effects of the present invention, such as a lubricant, pigment, dye, antioxidant, light stabilizer, light-shielding agent (for example, carbon black, titanium oxide, etc.). Additives known per se can also be contained as necessary.

(1) Pore diameter and pore volume of porous powder Using NOVA1000 manufactured by Yuasa Ionics Co., Ltd., an average pore diameter and total pore volume were determined using a pellet cell by a nitrogen gas adsorption method.

(2) Content of porous powder in polyester composition 10 g of the obtained polyester composition was sampled and measured in a crucible, and then gradually ashed on a heater adjusted to 300 to 400 ° C, and then 800 ° C. The crucible was transferred to an electric furnace and heated for 2 hours. After standing to cool, the crucible was weighed. The porous powder content was determined from the remaining amount.
Whether the powder is a porous powder is observed with an electron microscope. When particles other than porous powder are included, particles with different solubility are dissolved with an acid-alkali, and particles with different specific gravity are analyzed with a density method (weight (Liquid separation), and the porous powder content was calculated. Alternatively, the content of the porous powder may be calculated by calculating the respective weight ratios from the contained particle frequency observed with an electron microscope and the density of the particles.

(3) Intrinsic Viscosity The unit obtained by dissolving a sample of the obtained polyester composition in a phenol: trichloroethane mixed solvent having a weight ratio of 6: 4 and measuring at a temperature of 35 ° C. is represented by [dl / g].

(4) Number of terminal carboxyl groups After the obtained polyester composition was dissolved in benzyl alcohol at 200 ° C. under a nitrogen atmosphere, the number of carboxylic acid end groups (eq / t) was determined by titration as the number of equivalents per 1 t of polyester weight. ) Was measured.

(5) Bubble content After the polycondensation reaction, the inside of the polycondensation reaction kettle is pressurized to 0.17 Mpa with nitrogen gas, the polyester composition obtained from the die hole is extruded into a strand, and the polyester composition is cooled with a cooling bath. After that, cutting was performed with a letterer to obtain a cylindrical polyester chip having a major axis of about 4 mm, a minor axis of about 2 mm, and a length of about 4 mm. 25 g of this chip was visually observed with a universal scope (4 times magnification), and the number of bubbles having a diameter of 1 mm or more was measured.

(6) Hydrolysis resistance The obtained polyester composition was made into a chip state by the method of (5) above, and 10 g of the chip was manufactured by Hirayama Mfg. Co., Ltd., using a PC-3011 pressure cooker, temperature 105 ° C., humidity After the treatment for 64 hours under the condition of 100% RH, the whole amount of the chips was frozen and ground. The number of terminal carboxyl groups was measured for this sample, and the increase in the number of terminal carboxyl groups before and after the pressure cooker treatment was evaluated. The lower the increase in the number of terminal carboxyl groups, the better the hydrolysis resistance.

(7) Number of surface defects of film The obtained polyester composition was converted into a chip state by the method of (5), and the chip was dried at 160 ° C. for 6 hours in an electric dryer, and then an extruder manufactured by Hitachi, Ltd. (P40- 22AB type) was melt-extruded at 295 ° C., and a polyester sheet having a thickness of 125 μm was produced using a Nippon Steel Works 2-type film manufacturing apparatus (horizontal moving type). Next, the polyester sheet is stretched 3.5 times in the film forming direction (longitudinal direction or MD direction) at 120 ° C. and 3.0 times in the width direction (transverse direction or TD direction) at 120 ° C. A 12 μm film was obtained. This film was observed under polarized light with a microscope, and the number of surface protrusions due to bubbles was evaluated according to the following criteria.
Number of surface protrusions: counted at a film area of 25 cm2 for a major axis of 30 μm or more (measured times, n = 5)
0 ≤ Number of surface protrusions ≤ 5 Very good (◎)
5 <number of surface protrusions ≤ 10 Good (○)
10 <number of surface protrusions ≤ 15 Slightly poor (x)
15 <Number of surface protrusions, not usable (XX)

[Example 1]
Dissolve 1.22 parts of manganese acetate tetrahydrate in 124.1 parts of ethylene glycol, add 118.1 parts of dimethyl oxalate, and heat to 160 ° C to distill off the methyl alcohol produced as a result of the transesterification reaction. It was. Next, 0.41 part of phosphorous acid was added, and the pressure was gradually reduced under a nitrogen atmosphere, and the mixture was heated and reacted at 2.7 kPa for about 10 minutes. Thereafter, 30 parts of zeolite powder having a pore diameter of 5 mm was added to prepare a mixture 1 of porous powder and PEO.
Next, 100 parts by weight of dimethyl terephthalate, 60 parts by weight of ethylene glycol, and 0.019 part of manganese acetate tetrahydrate were charged in a transesterification reaction vessel, heated to 150 ° C., melted and stirred. The reaction was advanced while the temperature inside the reaction vessel was slowly raised to 235 ° C., and the methanol produced was distilled out of the reaction vessel. When the distillation of methanol was completed, 0.014 part of phenylphosphonic acid (17 mmol% based on the number of moles of dimethyl terephthalate) was added as a phosphorus compound to complete the transesterification reaction. Subsequently, 0.05 part of antimony trioxide and 0.005 part of tetrabutoxy titanate were added as a polycondensation catalyst after 5 minutes and heated to 240 ° C. to distill a part of ethylene glycol. It shifted to the polycondensation apparatus which has a stirring blade inside.

  After completion of the transesterification reaction, the reaction product was subjected to a polycondensation reaction, and the reaction temperature was allowed to reach 270 ° C. for 35 minutes while gradually increasing the degree of vacuum with a vacuum pump. While maintaining this temperature, the degree of vacuum was kept at 0.15 kpa or less, and the polycondensation reaction was carried out for 15 minutes. Here, the vacuum valve connecting the vacuum pump and the PN reaction kettle was closed, and the stirring blade was kept rotating, and immediately heated in a vacuum hopper to be liquid, the mixture 1 (1.0 part of PEO polymer ( After adding 0.25 parts of zeolite powder having a pore size of 5 mm) to 1.2 mol% of the total acid components constituting the polyester, the vacuum valve was immediately opened to resume the decompression process. The intrinsic viscosity of the polyester when PEO was added was 0.25 dl / g. Thereafter, a polycondensation reaction was performed for 110 minutes. Next, after the stirring blade was stopped to perform the polymer discharging operation, the inside of the PN reaction kettle system was pressurized to 0.17 MPa with nitrogen gas, and the polyester was extruded from the die hole into a strand shape. Thereafter, the polyester was cooled with a cooling bath, and then cut with a letterer to obtain a polyester composition in a state of a polyester chip having a major axis of about 4 mm, a minor axis of about 2 mm, and a length of about 4 mm. Table 1 shows the properties and evaluation of the obtained polyester composition.

[Example 2]
The same operation as in Example 1 was repeated except that the powder to be added was changed to zeolite having a pore diameter of 7 mm. Table 1 shows the properties and evaluation of the obtained polyester composition.

[Example 3]
The same operation as in Example 1 was repeated except that the powder to be added was changed to molecular sieves having a pore size of 10 mm. Table 1 shows the properties and evaluation of the obtained polyester composition.

[Examples 4 to 5]
The same operation as in Example 1 was repeated except that the amount of the porous powder added to the mixture 1 and the amount of the mixture to be added were changed so that the amount of PEO to be added was the amount shown in Table 1. Table 1 shows the properties and evaluation of the obtained polyester composition.

[Example 6]
The same operation as in Example 1 was repeated except that the amount of the porous powder added to the mixture 1 and the amount of the mixture added were changed so that the amount of the porous powder added was the amount shown in Table 1. Table 1 shows the properties and evaluation of the obtained polyester composition.

[Example 7]
In Example 1, the same operation as in Example 1 was repeated except that 1.75 parts of zeolite powder having a pore size of 5 mm was added at the end of the transesterification reaction. Table 1 shows the properties and evaluation of the obtained polyester composition.

[Comparative Examples 1-2]
The same operation as in Example 1 was repeated except that the amount of the porous powder added to the mixture 1 and the amount of the mixture to be added were changed so that the amount of PEO to be added was the amount shown in Table 1. Table 1 shows the properties and evaluation of the obtained polyester composition.

[Comparative Example 3]
The same operation as in Example 1 was repeated except that the porous powder to be added was changed to zeolite having a pore diameter of 3 mm. Properties and evaluation of the obtained polyester are shown in Table 1.

[Comparative Example 4]
The same operation as in Example 1 was repeated except that the amount of porous powder added to the mixture 1 and the amount of mixture added were changed so that the amount of zeolite to be added was the amount shown in Table 1. Table 1 shows the properties and evaluation of the obtained polyester composition.

[Comparative Example 5]
In Example 1, the same operation as in Example 1 was repeated except that 5.25 parts of zeolite powder having a pore size of 5 mm was added at the end of the transesterification reaction. Table 1 shows the properties and evaluation of the obtained polyester composition.

[Comparative Example 6]
The same operation as in Example 1 was repeated except that the mixture 1 was not added. Table 1 shows the properties and evaluation of the obtained polyester composition.

[Comparative Example 7]
The same operation as in Example 1 was repeated except that no zeolite was added to the mixture 1. Properties and evaluation of the obtained polyester composition are shown in Table-1.

  PEO in Table 1 means glycol ester of oxalic acid, and MS means molecular sieves.

  The polyester composition of the present invention is extremely useful as a film for a solar battery back sheet, which is particularly required to have hydrolysis resistance, since the number of bubbles contained in the polymer is small even when PEO is added and the amount of terminal carboxyl groups is small. It can be used suitably.

Claims (5)

A polyester composition comprising an aromatic dicarboxylic acid as a main acid component and ethylene glycol as a main glycol component, wherein a glycol ester of oxalic acid represented by the following formula (1) (hereinafter abbreviated as PEO) is used as a total acid component. A hydrolysis-resistant polyester composition containing 0.1 to 5.0 mol% of a porous powder having a pore diameter of 4 mm or more in a range of 0.1 to 5% by weight.

  The hydrolysis-resistant polyester composition according to claim 1, wherein the porous powder is zeolite. In the method for producing a polyester composition having an aromatic dicarboxylic acid as a main acid component and an ethylene glycol as a main glycol component, an oxalic acid glycol ester represented by the following formula (1) is added to the total acid component of the polyester. Adding in the range of 0.1 to 5.0 mol%, and adding the porous powder having a pore diameter of 4 mm or more in the range of 0.1 to 5 wt% based on the weight of the obtained polyester composition The manufacturing method of the polyester composition which has a process to do.

  The method for producing a polyester composition according to claim 3, wherein the oxalic acid glycol ester is added after the addition of the porous powder or together with the porous powder.   The method for producing a polyester composition according to claim 4, wherein the porous powder is added to glycol oxalate during the synthesis reaction of the oxalate glycol ester.