JP5078378B2 - Polyester resin composition - Google Patents

Description

  The present invention relates to a polyester resin composition that is excellent in hydrolysis resistance and in which deterioration of resin properties with time is suppressed.

When a polymer material is used for food packaging, fibers, etc., long-term stability of the resin is required in order to prevent deterioration of the contents and maintain practical strength. However, for example, in the case of a polyester resin, there is a drawback that the molecular weight and strength are easily lowered by hydrolysis.
Therefore, studies have been made on additives in order to improve hydrolysis resistance.

  For example, JP-A-46-5389 discloses a method of adding biscarbodiimide to polyester, and JP-B-38-15220 discloses a method of adding a carbodiimide compound containing three or more carbodiimide groups in the molecule. Although each has been proposed, the effect of improving hydrolysis resistance is low.

Japanese Patent Application Laid-Open No. 2003-192929 discloses a composition containing a biodegradable organic polymer compound, a flame retardant additive, and a hydrolysis inhibitor. However, there is no indication as to the influence of hydroxide compounds, phosphorus compounds, silica compounds, and the like exemplified as flame retardant additives on hydrolysis resistance.
Japanese Patent Laid-Open No. 46-5389 Japanese Examined Patent Publication No. 38-15220 JP 2003-192929 A

  An object of the present invention is to provide a novel polyester resin having a significantly improved hydrolysis rate in a humidity environment. Another object of the present invention is to provide a polyester resin composition that includes a hydrolysis inhibitor and a hydrolysis inhibition assistant, has hydrolysis resistance, and retains resin properties over a long period of time.

As a result of intensive studies in view of the above problems, the present inventors have found that a resin composition to which a hydrolysis inhibitor and a phosphorus-based stabilizer are added solves the above problems, and have completed the present invention.
That is, in the present invention, 0.01 to 15 parts by weight of the hydrolysis inhibitor (B), which is a carbodiimide compound, and 0.01 to 1 part of the phosphorus stabilizer (C) with respect to 100 parts by weight of the polyester resin (A). Ri Na comprise parts,
When the polyester resin (A) has 100% by mole of all the structural units,
(1) 90-98 mol% of glycolic acid units
(2) 5 to 1 mol% of aromatic dicarboxylic acid unit
(3) 5 to 1 mol% of diol units
It is related with the polyester resin composition characterized by including each .

Further, the present inventors have found that a resin composition to which a hydrolysis inhibitor, a phenol-based stabilizer, and a phosphorus-based stabilizer are added solves the above-described problems, and has completed the present invention.
That is, in the present invention, 0.01 to 15 parts by weight of the hydrolysis inhibitor (B), which is a carbodiimide compound, and 0.01 to 1 part by weight of the phosphorus stabilizer (C) with respect to 100 parts by weight of the polyester resin (A). And 0.01 to 1 part by weight of a phenol-based stabilizer (D) ,
When the polyester resin (A) has 100% by mole of all the structural units,
(1) 90-98 mol% of glycolic acid units
(2) 5 to 1 mol% of aromatic dicarboxylic acid unit
(3) 5 to 1 mol% of diol units
It is related with the polyester resin composition characterized by including each .

A polyester resin composition in which the composition further comprises 0.01 to 3 parts by weight of a hydrolysis inhibiting aid (E) is preferred;
Hydrolysis inhibitor (E): magnesium oxide and calcium oxide, aluminum hydroxide, magnesium hydroxide and calcium hydroxide, magnesium carbonate and calcium carbonate, hydrotalcite.

Furthermore, the present inventors have especially made a hydrolysis inhibitor, a phenol-based stabilizer, a resin composition to which a phosphorus-based stabilizer is added, and a specific hydrolysis-inhibiting aid to the composition, particularly with respect to an oxycarboxylic acid copolymerized polyester resin. The present invention has been completed by finding that a resin composition to which is added is suitable for solving the above problems. That is, in the polyester resin composition of the present invention, the polyester resin (A) is a polyester resin containing each of the units (1) to (3) when the total structural unit is 100 mol% .

Furthermore, it is particularly preferable to use a carbodiimide compound as the hydrolysis inhibitor (B) in order to solve the above problems.
Furthermore, it is particularly preferable that the phenol-based stabilizer (D) is a hindered phenol-based stabilizer in order to solve the above problems.

According to the present invention, there is provided a polyester resin composition in which hydrolysis, which is a defect of a polyester resin, is remarkably suppressed. According to the present invention, since it is possible to suppress a decrease in physical properties of a polyester resin widely used in films, sheets, beverage containers and the like, it is extremely useful industrially.

In the present invention, 0.01 to 15 parts by weight of a hydrolysis inhibitor (B), which is a carbodiimide compound, and 0.01 to 1 part by weight of a phosphorus stabilizer (C) with respect to 100 parts by weight of the polyester resin (A). A polyester resin composition comprising parts.

Moreover, this invention is 0.01-15 weight part of hydrolysis inhibitors (B) which are carbodiimide compounds with respect to 100 weight part of polyester resins (A), and 0.01-0.1 of phosphorus stabilizer (C). A polyester resin composition comprising 1 part by weight and 0.01 to 1 part by weight of a phenol-based stabilizer (D).

Moreover, this invention adds 0.01-3 weight of hydrolysis inhibitor further to the composition which consists of said (A) (B) (C) or (A) (B) (C) (D). A polyester resin composition comprising parts.
Hydrolysis inhibitor (E): magnesium oxide and calcium oxide, aluminum hydroxide, magnesium hydroxide and calcium hydroxide, magnesium carbonate and calcium carbonate, hydrotalcite.

Po Riesuteru resin (A) used in the present invention, when the total of all structural units is 100 mol%,
(1) glycolic acid units 90-98 mol%
(2) 5 to 1 mol% of aromatic dicarboxylic acid unit
(3) 5 to 1 mol% of diol units
Including each
The polyester resin composition of the present invention comprises 0.01 to 15 parts by weight of a hydrolysis inhibitor (B), which is a carbodiimide compound, and a phosphorus stabilizer (C) with respect to 100 parts by weight of the polyester resin (A). A polyester resin composition comprising 0.01 to 1 part by weight is exemplified.

Moreover, 0.01-15 weight part of hydrolysis inhibitors (B) which are carbodiimide compounds, and 0.01-1 weight part of phosphorus stabilizer (C) with respect to 100 weight part of said polyester resins (A). And a polyester resin composition comprising 0.01 to 1 part by weight of a phenol-based stabilizer (D).

Moreover, 0.01-15 weight part of hydrolysis inhibitors (B) which are carbodiimide compounds, and 0.01-1 weight part of phosphorus stabilizer (C) with respect to 100 weight part of said polyester resins (A). And a polyester resin composition comprising 0.01 to 1 part by weight of a phenol-based stabilizer (D) and 0.01 to 3 parts by weight of a hydrolysis inhibitor (E).
Hydrolysis inhibitor (E): magnesium oxide and calcium oxide, aluminum hydroxide, magnesium hydroxide and calcium hydroxide, magnesium carbonate and calcium carbonate, hydrotalcite

[Polyester resin]
The polyester resin used in the present invention is not particularly limited as long as it is the polyester resin (A) described above .

In the present invention , glycolic acid is used among oxycarboxylic acids because a polyester resin having a high gas barrier property can be obtained . In particular, polyglycolic acid that is easily hydrolyzed is preferable because the effects of the phenol-based stabilizer (D), the phosphorus-based stabilizer (C), and the hydrolysis-inhibiting aid (E) are more prominent.
When glycolic acid to 100 mol% of all the structural units of the polyester resin, 90 to 98 mol%, more preferably, includes 95-97 mole%.

The aromatic dicarboxylic acid used in the present invention is not particularly limited.
The aromatic dicarboxylic acids may contain, specifically, isophthalic acid, terephthalic acid, phthalic acid, and aromatic dicarboxylic acids having 8 to 12 carbon atoms such as 2,6-naphthalene dicarboxylic acid.
In the present invention, by using an aromatic dicarboxylic acid, gas barrier properties, Ru provides excellent polyester mechanical properties. In particular, at least one selected from isophthalic acid, 2,6-naphthalenedicarboxylic acid, and terephthalic acid is preferable. It is particularly preferable to use isophthalic acid.
When these aromatic dicarboxylic acids to 100 mol% of all the structural units of the polyester resin, 5 to 1 mol%, more preferably includes from 2.5 to 1.5 mol%.
These aromatic dicarboxylic acids may be used alone or in combination of two or more.

The diol used in the present invention is not particularly limited.
Specific examples of the diol that may be contained include aliphatic diols having 5 or more carbon atoms such as 1,6-hexanediol, neopentyl glycol, dodecamethylene glycol, triethylene glycol, and tetraethylene glycol, and cyclohexanedimethanol. Alicyclic diols, 1,3-bis (2-hydroxyethoxy) benzene, 1,2-bis (2-hydroxyethoxy) benzene, 1,4-bis (2-hydroxyethoxy) benzene, bis [4- ( Examples include diols containing aromatic groups such as 2-hydroxyethoxy) phenyl] sulfone, 2,2-bis (4-β-hydroxyethoxyphenyl) propane, bisphenols, hydroquinone, and resorcin.
These diols can and the total of all structural units of the polyester resin to 100 mol%, 5 to 1 mol%, more preferably includes from 2.5 to 1.5 mol%.

Preferably, an aliphatic diol having 4 or less carbon atoms is used.
Examples of the aliphatic diol having 4 or less carbon atoms include ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, and the like. These aliphatic diols may be used alone or in combination of two or more. Among these, it is preferable to use ethylene glycol.

Moreover, the polyester resin used for this invention may contain 0.001-2 mol% of monomer units of the functional number 3 or more which have ester formation ability as needed, More preferably, it is 0.01-0.4 mol. % May be contained.
Examples of the monomer unit having 3 or more functional groups include units derived from polyfunctional carboxylic acids having 3 or more carboxyl groups or polyfunctional alcohols having 3 or more hydroxyl groups, and those having 3 or more carboxyl groups and hydroxyl groups. Examples include units derived from functional hydroxy acids.

Among these, it is preferable to contain units derived from polyfunctional alcohols having 3 or more hydroxyl groups. Specifically, glycerin, diglycerin, (trishydroxymethyl) methane, 1,1,1- (trishydroxymethyl) ethane, 1,1,1- (trishydroxymethyl) propane, pentaerythritol, dipenta Units derived from erythritol, sugars such as sorbitol, glucose, lactose, galactose, fructose, saccharose, and nitrogen-containing polyhydric alcohols such as 1,3,5-trishydroxyethoxyisocyanurate.
Among these, it is more preferable to select from units derived from glycerin, 1,1,1 (trishydroxymethyl) ethane, 1,1,1 (trishydroxymethyl) propane, pentaerythritol, and dipentaerythritol.

  In the polyester resin of the present invention, a heat stabilizer, a weather stabilizer, an ultraviolet absorber, a nucleating agent, an inorganic filler, a lubricant, a slip agent, an anti-blocking agent, and a stabilizer, which are blended in the conventional polyester as necessary. In addition, an appropriate amount such as an antistatic agent, an antifogging agent, a pigment, an oxygen absorbent, or a terminal blocking agent may be blended.

[Hydrolysis inhibitor (B)]
In the present invention, a carbodiimide compound is used as the hydrolysis inhibitor (B) . Among these carbodiimide compounds of the hydrolysis inhibitor has an effect of suppressing more effectively hydrolyzed.
It is preferable that 0.01-15 weight part is added with respect to a polyester resin (A), and it is more preferable that 0.5-5 weight part is added especially.
Hydrolysis inhibitor (B) is selected carbodiimide compound or these following may be used singly, or may be used by mixing two or more kinds.

  The carbodiimide compound is a compound having one or more carbodiimide groups in the molecule, and includes a polycarbodiimide compound having two or more functions.

  Examples of monocarbodiimide compounds include dicyclohexyl carbodiimide, diisopropyl carbodiimide, dimethyl carbodiimide, diisobutyl carbodiimide, dioctyl carbodiimide, diphenyl carbodiimide, naphthyl carbodiimide, and the like.

Examples of polycarbodiimide compounds include poly (dicyclohexylcarbodiimide), poly (isopropylcarbodiimide), poly (dimethylcarbodiimide), poly (diisobutylcarbodiimide), poly (dioctylcarbodiimide),
Poly (4,4′-diphenylmethanecarbodiimide), poly (3,3′-dimethyl-4,4′-diphenylmethanecarbodiimide), poly (tolylcarbodiimide), poly (p-phenylenecarbodiimide), poly (m-phenylenecarbodiimide) , Poly (1,3-diisopropylphenylenecarbodiimide), poly (1-methyl-3,5-diisopropylphenylenecarbodiimide), poly (1,3,5-triethylphenylenecarbodiimide), poly (triisopropylphenylenecarbodiimide), poly ( Naphthylcarbodiimide) and the like. These can also use 2 or more types together.

[Phosphorus stabilizer (C)]
Examples of the phosphorus stabilizer (C) include phosphoric acid, phosphoric acid ester, phosphorous acid, and phosphorous acid ester. Phosphoric acid esters and phosphite esters are preferred, and phosphite stabilizers are more preferred.
The phosphorous stabilizer (C) is preferably added in an amount of 0.01 to 1 part by weight, more preferably 0.05 to 0.5 part by weight, based on the polyester resin (A).

The phosphorus stabilizer (C) may be selected from the following compounds and used alone or in combination of two or more.
Examples of phosphorus stabilizers (C) are phosphite tris (2,4-di-t-butylphenyl) phosphite, bis (2,6-di-t-butyl-4-methylphenyl) Pentaerythritol di-phosphite, distearyl pentaerythritol diphosphite, 3,5-di-t-butyl-4-hydroxybenzylphosphoric acid distearyl ester, tris (3,5-di-t-butyl- 4-hydroxyphenyl) phosphite, triphenyl phosphite, tetrakis (2,4-di-t-butylphenyl) 4,4'-biphenylene diphosphite and the like, and distearyl pentaerythritol diphosphite is particularly preferable. .
Examples of the phosphate ester include trimethyl phosphate, triethyl phosphate, tri n-butyl phosphate, trioctyl phosphate, triphenyl phosphate, tricresyl phosphate, and the like.

In addition, 6- [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propoxyl] -2,4,8,10-tetra-t-butyldibenz [d, f] [1,3, 2] Phosphorus stabilizers containing phenolic hydroxyl groups such as dioxaphosphepine (Sumitomo Chemical Co., Ltd., Sumilizer GP) can also be used.
In the present invention, the phosphorus stabilizer containing a phenolic hydroxyl group is treated as a phosphorus stabilizer (C), not a phenol stabilizer (D).

[Phenolic stabilizer (D)]
The phenol-based stabilizer (D) is preferably a hindered phenol-based stabilizer.
The hindered phenol-based stabilizer is a compound having an alkyl group at both ortho positions of the hydroxyl group of phenol. The alkyl groups are each independently an alkyl group having 1 to 4 carbon atoms, specifically, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, s-butyl group. Group and t-butyl group.
The phenolic stabilizer (D) and the phenolic stabilizer (D) are preferably added in an amount of 0.01 to 1 part by weight, particularly 0.05 to 0.5 parts by weight, based on the polyester resin (A). More preferably.

Examples of phenolic stabilizers (D) include
Tetrakis (methylene-3 (3,5-di-t-butyl-4-hydroxyphenyl) propionate) methane, 2,6-di-t-butylphenol, 3,5-di-t-butyl-4-hydroxytoluene, Examples thereof include n-octadecyl-3- (4′-hydroxy-3 ′, 5′-di-t-butylphenyl) propionate, and particularly tetrakis (methylene-3 (3,5-di-t- Butyl-4-hydroxyphenyl) propionate) methane is preferred.
These phenol stabilizers may be used alone or in combination of two or more.

[Hydrolysis inhibitor (E)]
The hydrolysis inhibitor (E) is selected from magnesium oxide and calcium oxide, aluminum hydroxide, magnesium hydroxide and calcium hydroxide, magnesium carbonate and calcium carbonate, and hydrotalcite.
Hydrolysis inhibition aid (E) is usually added in an amount of 0.01 to 3 parts by weight, but if added in a large amount, it tends to crystallize at the time of molding and the transparency is impaired, so in applications where transparency is required. The added amount is preferably 0.01 to 2 parts by weight, more preferably 0.01 to 1 part by weight.
Since the compound has an effect of neutralizing an acid generated by hydrolysis of polyester, it is considered to have an effect of suppressing a decrease in molecular weight due to hydrolysis.

[Production method]
A method for producing a composition comprising a polyester resin, a hydrolysis inhibitor, a phenol-based stabilizer, a phosphorus-based stabilizer, and a hydrolysis-inhibiting aid added as necessary is not particularly limited, and a known method can be used. . Examples of the apparatus for performing the melt mixing include a single screw extruder, a twin screw extruder, a plast mill, a kneader, various extrusion molding machines and injection molding machines, or a reactor equipped with a stirring device and a decompression device. Further, it is desirable that this melt mixing is performed under an inert gas atmosphere and / or under reduced pressure.
When preparing the composition, the additive may be melt-kneaded in advance in the resin, or may be melt-kneaded in a cylinder of an injection molding machine at the time of molding.

  The order of addition in the case of melt kneading may be simultaneous or any one of them. Moreover, the composition obtained by melt-kneading any of them in the polyester resin first may be further melted, and the remaining additives may be added and melt-kneaded.

  Furthermore, the polyester resin composition obtained by melt mixing is further maintained at a temperature below its melting point under reduced pressure or in an inert air stream for 20 minutes to 100 hours, and subjected to solid phase polymerization. Also good. A known method can be adopted as the solid-phase polymerization method. For example, a pellet of the polyester resin composition is placed in an inert gas atmosphere for 1 to 300 minutes under a temperature range of 80 ° C. to 30 ° C. below the melting peak temperature. After preliminarily crystallizing by maintaining, solid phase polymerization can be performed by maintaining for 1 to 100 hours in a temperature range of 130 ° C. to 10 ° C. below the melting peak temperature.

[Usage]
The polyester resin of the present invention can be used in an unstretched state as a raw material for a film, a sheet, a hollow molded container, or other shaped articles having various shapes by an ordinary molding method. Furthermore, even if the polyester resin is molded in a stretched state as a film, a sheet, or a hollow molded container, a molded body having further excellent gas barrier properties can be obtained.

The polyester resin of the present invention may be blended and used as a gas barrier property modifier for other resins. Examples of other resins to which the polyester resin of the present invention is added include polyolefin resins such as polyethylene, polypropylene, and cyclic polyolefin, and resins such as polyester resins and polyamide resins. Among these, the polyester resin is uniformly mixed. It is preferable in that it is.
Furthermore, the polyester resin of the present invention can also be used in a form laminated with other resins.

Examples of other resins used for laminating with the polyester resin of the present invention include polyolefin resins such as polyethylene, polypropylene, and cyclic polyolefin, and resins such as polyester resins and polyamide resins. It is preferable because it has good stability and does not require the use of a special adhesive.
The blended molded product and the laminated molded product can be applied not only to films, sheets, plates, and tubular products, but also to molded products of various shapes such as hollow bodies and containers. The molded body can be produced by a conventionally known method.

  The present invention will be described more specifically with reference to the following examples, but the present invention is not limited to these examples. The physical properties of the resin of this example were measured and evaluated by the following methods.

(Reduced viscosity)
The reduced viscosity IV of the polyester resin was measured at 25 ° C. in a mixed solution of phenol and tetrachloroethane (weight ratio 1/1).

(Additive)
The kneaded additive is shown below.
・ HMV-10B; Multivalent carbodiimide (Nisshinbo Co., Ltd.)
Irgafos 168; Tris (2,4-di-t-butylphenyl) phosphite (manufactured by Ciba Specialty Chemicals)
-PEP-8; distearyl pentaerythritol diphosphite (manufactured by ADEKA Corporation)
-PEP-36; bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol phosphite (manufactured by ADEKA Corporation)
(PhO) ₃ PO; triphenyl phosphate Irganox 1010; tetrakis (methylene-3 (3,5-di-t-butyl-4-hydroxyphenyl) propionate) methane (manufactured by Ciba Specialty Chemicals)
Aluminum hydroxide; Heidilite H-42S (made by Showa Denko KK)

(Hydrolysis acceleration test)
A 300 μm-thick amorphous press sheet was hung in a constant temperature and humidity chamber (PR-1G type) manufactured by Tabai Co., Ltd. under an atmosphere set to 38 ° C. and relative humidity 85%, and the change in reduced viscosity (IV) with time was measured. pursued.
In addition, the numerical value of the lower right of IV value represents the elapsed days from the start of a hydrolysis promotion test, respectively. Moreover, as an index indicating the maintenance ratio of the molecular weight after hydrolysis, the reduced viscosity (IV ₇ ) of the press sheet after being maintained for 7 days under the above hydrolysis promotion conditions, and the reduced viscosity of the press sheet before the hydrolysis promotion test ( The ratio of IV ₀ ) (IV ₇ / IV ₀ ) was used.

(Production Example 1)
Glycolic acid 304 g (4.0 mol), isophthalic acid 17.4 g (0.11 mol), and ethylene glycol 8.5 g (0.14 mol) were charged into a reaction vessel, and 150-180 while distilling off the generated water. The esterification reaction was performed at 7 ° C. for about 7 hours.

  The obtained polyester oligomer was charged into a glass reactor equipped with a stirrer and a distillation pipe. The distilling pipe is connected to a vacuum device composed of a vacuum pump and a decompression regulator, and has a structure capable of distilling off the evaporated material. A germanium-based catalyst (germanium dioxide) was added thereto and first melted at 220 ° C. under a nitrogen stream, and then the pressure was reduced to about 1 torr over about 1 hour with stirring to maintain the conditions. The reaction was carried out for about 6 hours after reaching the condition of about 1 torr, and the produced ethylene glycol and oligomer were distilled out of the system. After this polycondensation reaction, the resin was extruded in a strand form from a nozzle and cut into pellets. The reduced viscosity IV of the obtained polyester resin was 0.720 dl / g. Next, the resulting resin was pre-crystallized by heating at 120 ° C. for 2 hours under a nitrogen atmosphere, and then solid-phase polymerization was performed by maintaining at 190 ° C. for 24 hours. The reduced viscosity of the obtained polyester resin was 0.920 dl / g.

Example 1
100 parts by weight of the polyester resin obtained in Production Example 1, sufficiently dried by a vacuum dryer, 5 parts by weight of polycarbodiimide (Carbodilite HMV-10B manufactured by Nisshinbo Co., Ltd.), and tris (2,4-di-t-butyl) Phenyl) phosphite (Irgafos 168 manufactured by Ciba Specialty Chemicals Co., Ltd.) and 0.5 parts by weight are melt-mixed for 3 minutes under the condition of a rotor rotational speed of 100 rpm in a Laboplast mill (manufactured by Toyo Seiki Co., Ltd.) at a temperature of 220 ° C. Went.

Next, after the resulting resin composition was sufficiently dried with a vacuum dryer, a predetermined amount was sandwiched between the two brass plates, the aluminum plate, and the release film, melted at 240 ° C. with a compression molding machine, and 30 at 10 MPa. Compressed for seconds. Then, it was compressed and cooled again at 10 MPa with a compression molding machine set at 0 ° C. to produce a press sheet having a thickness of about 300 μm. The reduced viscosity IV ₀ of the press sheet was 0.798 dl / g. The obtained sheet was stored in a constant temperature and humidity chamber at 38 ° C. and a relative humidity of 85%, and a hydrolysis resistance acceleration test was performed.
Table 1 below shows the reduced viscosity change with time and the reduced viscosity maintenance rate after 7 days of the examples and comparative examples.

(Examples 2 to 7)
Except for changing the types and amounts of additives as shown in Table 1, melt mixing and press sheets were prepared in the same manner as in Example 1, and the hydrolysis resistance test was conducted.

(Comparative Example 1)
Except that 5 parts by weight of polycarbodiimide was used as an additive and no phosphorus stabilizer was added, melt kneading was carried out in the same manner as in Example 1 to prepare a press sheet and a hydrolysis resistance test.

(Comparative Example 2)
The melt kneading was carried out in the same manner as in Example 1 except that 5 parts by weight of polycarbodiimide and 0.5 parts by weight of a phenol stabilizer (Irganox 1010) were used as additives and no phosphorus stabilizer was added. Sheeting and hydrolysis resistance tests were performed.

  In any of the examples, the reduced viscosity is temporarily increased by forming a crosslinked structure by a reaction between polycarbodiimide and a terminal carboxyl group newly generated by hydrolysis of polyester. Thereafter, the slope decreases with the progress of hydrolysis. However, since the progress of hydrolysis is suppressed in the examples of the present invention, the ratio of reduced viscosity [IV7 / IV0] is larger than that of the comparative example.

Claims (4)

It comprises 0.01 to 15 parts by weight of a hydrolysis inhibitor (B), which is a carbodiimide compound, and 0.01 to 1 part by weight of a phosphorus stabilizer (C) with respect to 100 parts by weight of the polyester resin (A). ,
When the polyester resin (A) has 100% by mole of all the structural units,
(1) 90 to 98 mol% of glycolic acid units
(2) 5 to 1 mol% of aromatic dicarboxylic acid unit
(3) 5 to 1 mol% of diol units
A polyester resin composition comprising each of the above. 0.01 to 15 parts by weight of a hydrolysis inhibitor (B), which is a carbodiimide compound, 0.01 to 1 part by weight of a phosphorus stabilizer (C), and 100 parts by weight of the polyester resin (A) Comprising 0.01 to 1 part by weight of stabilizer (D),
When the polyester resin (A) has 100% by mole of all the structural units,
(1) 90 to 98 mol% of glycolic acid units
(2) 5 to 1 mol% of aromatic dicarboxylic acid unit
(3) 5 to 1 mol% of diol units
A polyester resin composition comprising each of the above.   The polyester resin composition according to claim 1 or 2, further comprising 0.01 to 3 parts by weight of a hydrolysis inhibiting aid (E) which is aluminum hydroxide.   The polyester resin composition according to claim 2 or 3, wherein the phenol-based stabilizer (D) is a hindered phenol-based stabilizer.